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, doi: 10.14133/j.cnki.1008-9357
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, doi: 10.14135/j.cnki.1006-3080.
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$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190307001 [Abstract](952) [FullText HTML](249) [PDF 1116KB](11) Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI). Display Method: [Abstract](84) [FullText HTML](45) [PDF 679KB](2) Abstract: Study on the preparation of fulvic acid and humic acid from nitric acid-oxidized rice straw by through single factor analysis and orthogonal experiment, the effects of concentration of nitric acid, temperature, time and liquid-solid ratio on the yield of fulvic acid and humic acid were investigated, and optimal process conditions for fulcic acid were obtained. The result of single analysis shows that increase the concentration of HNO3 within a certain range, increase reaction temperature and increase reaction time can increase the yield of fulvic acid, the effect of liquid-solid ratio on the yield of FA and HA was not significant. The same conclusion was obtained by the range analysis of the FA yield in the orthogonal experiment. The optimal conditions obtained by the orthogonal experiment are: HNO3 concentration 5%(quality score), reaction temperature 90 ℃, liquid-solid ratio 13/1(mL/g), the average yield of fulvic acid of the reaction for 1 h was 32.63%, the yield of humic acid was 12.77% under this condition. Elemental analysis shows that C/O of the FA and HA is 0.87 and 1.93, the C/H of the FA and HA is 0.78 and 0.73, which indicated the high biological activity and obvious aroma characteristics of the product. Infrared spectroscopy showed that FA contains obvious aromatic characteristics, acidic groups and nitro groups which proved the oxidation and nitrification of HNO3, the nitro group of HA is not obvious. The UV-visible spectrum analysis showed that the E4/E6 of the FA was 13.87 and the HA was 8.47, both are higher than FA and HA prepared from low rank coal which further expressed its higher activity. 牛永健, 杨澜, 朱诗杰, [Abstract](88) [FullText HTML](41) [PDF 931KB](0) Abstract: The contact angles of five types of fine ash with different particle size distributions from opposed multi-burner coal water slurry gasification were measured by Washburn riser, and the reference solution for measuring the effective radius is n-hexane. X-ray diffraction and fourier infrared spectrometer were used to determine the XRD pattern and infrared spectrum of the fine ash. The surface groups, crystal mass fraction and crystallinity of inorganic minerals were analyzed in order to find out the influence of physical and chemical properties on its wettability. The results show that the contact angle of the opposed multi-burner coal water slurry gasification fine ash decreases as the particle size increases, but it does not change monotonously with the particle size. In addition to the particle size, the contact angle is still affected by other physical and chemical properties. Surface groups mainly composed of Si−O−Si and −OH and inorganic minerals mainly composed of SiO2 are the main physical and chemical properties that affect the wetting characteristics of particles in addition to particle size. All three factors contribute to the enhancement of particle wettability. There is a good linear relationship between the peak areas of the surface groups of Si−O−Si and −OH in the infrared spectrum and the contact angle of fine coal gasification ash. As the peak area of the group increases, the wetting contact angle decreases. It indicates thatt the surface group peak area represented by Si−O−Si and −OH can be used as a quantitative index to characterize the wettability of the same coal gasification fine ash. [Abstract](73) [FullText HTML](40) [PDF 874KB](1) Abstract: Attackers use software vulnerabilities to hijack the execution flow of the program, direct it to the malicious code or instructions that compose the malicious code, and finally achieve the purpose of controlling the behavior of the entire system. This kind of malicious attack is called control flow attack. Based on research of the principle of control flow attack, we propose a method based on the return address signature to detect control flow attack. The scheme firstly triggers pseudo random number generator to generate the key K to perform XOR encrypt operation with the return address that push into stack when the processor executes the call instruction, and uses the MD5 algorithm to generate the signature for the encrypted return address; Then, when processor executes the ret instruction, uses the MD5 algorithm to generate the signature for the encrypted return address that poped from stack. Finally, control flow attack can be detected according to whether the push_address signature matches the pop address signature. The experimental results show that the return address signature has good randomness and the control flow instruction that can be used to hijack the control flow is reduced to 81.27%, which can effectively prevent control flow attacks caused by maliciously tampering of the return address. [Abstract](68) [FullText HTML](51) [PDF 1069KB](0) Abstract: Cardiomyopathy is a common disease and an important cause of premature death. The development of a gene therapy vector for cardiomyopathy is the key to gene therapy of cardiomyopathy. In order to build a gene therapy vector targeting myocardium. In this study, the 8 selected AAV (AAV1-4, AAV6-9) capsid genes were recombined by DNA shuffling technology, and a random mutant AAV capsid library was constructed, and the random mutant AAV capsid library was constructed in mice Direct screening, and finally screened to obtain new AAV capsids with high myocardial targeting and low liver targeting, AAVH50 and AAVH59. Through the tail vein injection, the luciferase (Luciferase, Luc) gene carried by them was delivered to mice, and it was found that among the 11 tissues tested, the gene expression of AAVH50 and AAVH59 in myocardial tissue was higher than other tissues. Compared with AAV6 and AAV9, AAVH50 and AAVH59 expressed similar levels of luciferase in the myocardium, and the expression in the liver significantly decreased AAV9. After AAVH50 and AAVH59 infected primary neonatal rat cardiomyocytes, it was found that the efficiency of the selected AAVH59 in direct myocardial infection was significantly higher than that of AAV9. Therefore, this study screened to obtain a new type of AAV vector with high targeting to myocardium, and to the liver and low targeting, which is expected to provide a new type of AAV vector for gene therapy of myocardial diseases. [Abstract](162) [FullText HTML](93) [PDF 1065KB](1) Abstract: Compared with continuous process, batch process is an important industrial production mode with more flexibility. Products from each batch depend on market demands, which will make the process switch between different product stations. So, the final quality of products may become unstable due to various composition of raw materials. This kind of uncertainty brings great challenge to process modeling. Aiming at the problem of raw material uncertainty and the requirement of actual predicted value, the loss function of bidirectional gated recurrent unit neural network is modified, and then, utilized to predict the final quality prediction of unequal-length batch processes. The bidirectional gated recurrent unit neural network can integrate the time series information of the batch data, and fully exploit the inter-batch timing characteristics caused by the uncertainty of the raw materials. The improved loss function imposes different penalties on different predicted values such that the predicted values can meet the requirements in actual production. Finally, the proposed method is compared with multiple partial least squares (MPLS), neural network (NN), support vector regression (SVR) and gated recurrent unit (GRU) via an industrial process. It is shown via the results that the proposed method has better applicability and performs higher accuracy. [Abstract](87) [FullText HTML](55) [PDF 1233KB](1) Abstract: The effects of bubbles in the liquid jet on the air-blast atomization of viscous liquid were investigated using the Malvern laser particle size analyzer. The glycerol-water solution (Oh=3.46×10-2~0.407) is used as the liquid phase, and air as the gas phase. Experiments with various coaxial gas velocities (ug=94.8~142 m/s) and liquid jet velocities (ul,0=0.29~1.21 m/s) were conducted to study influences of inner bubbles on the droplets size. It was found that at low Oh, the droplet size decreases with the volumetric flow rate of aerating gas for the low liquid jet velocity, and the droplet size increase with the volumetric flow rate of aerating gas for the high liquid jet velocity; the droplet size increases with the volumetric flow rate of aerating gas at high Oh. A model is deduced to delineate the variation trend of the droplet size. We compared the predictions of this model with experimental results and found the relative deviations are less than ±5%. [Abstract](84) [FullText HTML](59) [PDF 1052KB](1) Abstract: A galactose-conjugated perylenediimide was loaded onto 2D MoS2 platform through π-π stacking, Moreover, encapsulating the antibiotic ceftazidime to form a P. aeruginosa-targeted therapeutic system. Perylenediimide as photosensitizer could produce reactive oxygen species upon light irradiation for photodynamic therapy, which further realizes combined chemo- and photodynamic therapy towards P. aeruginosa. This complexed system hugely reduces the dose of antibiotics, diminishes drug-resisting effects and provides new therapeutic insights for clinical-chronic bacteria. [Abstract](82) [FullText HTML](67) [PDF 1014KB](0) Abstract: The gasification characteristics of petroleum coke, fine slag and Shenfu coal char were comparatively studied using a high temperature stage microscope (HTSM) system. Petroleum coke mixed with Shenfu slag were prepared for comparison. The thermogravimetric analyzer (TGA) was used to compare the gasification reactivities of the different samples. It was found that the gasification reactivity of fine slag was obviously better than that of petroleum coke and slightly worse than that of Shenfu coal char at 1200 ℃. The addition of Shenfu slag accelerated the reaction rate of petroleum coke, indicating that the ash contained in the fine slag promoted the gasification reaction. The images of micro structure of petroleum coke and fine slag sample obtained from a scanning electron microscope showed that the surface of petroleum coke was very dense with few pores that can be clearly observed. The structure of fine slag particles was relatively loose. Micron-sized pores could be observed. The results of specific surface area and pore structure analysis showed that compared with petroleum coke, the pore structure of fine slag was developed after the gasification process that the specific surface area of which was about 15 times than petroleum coke. There were more 2-10 nm pores in the fine slag sample. The irregular pore structure of fine slag provided more surface for the gasification reaction and accelerated the gasification reaction rate. In addition, according to the results of the micro-Raman analysis, fine slag was relatively low in graphitization tendency compared with petroleum coke, which reflected the good gasification reactivity of fine slag. [Abstract](107) [FullText HTML](75) [PDF 1380KB](0) Abstract: P-glycoprotein (P-gp) is the first ABC transporter found to be associated with the sensitivity of cells to chemotherapeutic drugs. The main function of P-gp is to exclude exogenous substances from cells to prevent the body from absorbing harmful substances. Therefore, it was one of the self-defense and protection mechanisms under the physiological state of the body. However, this defense mechanism of P-gp protein also leads to the reduction of the concentration of some drug molecules in cells leading to multidrug resistance. The multidrug resistance of cells is one of the main reasons of the failure of chemotherapy. Therefore, inhibiting the efflux function of P-gp is one of the effective methods to reduce or even reverse multidrug resistance of cells. Quercitrin was a kind of flavonoid monomer compound with low biological toxicity, good water solubility, and weak P-gp inhibitory activity. In order to enhance the P-gp inhibitory activity of Quercitrin, we synthesized Quercitrin metal complexes Cu-Quercitrin and Zn-Quercitrin, and its P-gp inhibitory activity was investigated at the cellular level. Cu-Quercitrin could increase the accumulation of rhodamine 123 and doxorubicin in MCF-7/ADR cells, improve the cytotoxicity of doxorubicin. In fact, the effect of Cu-Quercitrin was significantly better than that of P-gp inhibitor Verapamil. In contrast, Cu-Querictrin had no effect on the accumulation of rhodamine 123 and doxorubicin in normal MCF-7 cells, suggesting that Cu-Quercitrin could inhibit P-gp transport function. Compared with the Cu-Quercitrin, Zn-Quercitrin had no significant effect on the accumulation of P-gp substrates rhodamine 123 and doxorubicin in drug-resistance MCF-7/ADR cells. Further studies showed that Cu-Quercitrin had no effect on the expression of P-gp, but reduced the adenosine triphosphate（ATP）content in drug-resistant cells. Therefore, Cu-Quercitrin increased the accumulation of anti-cancer drugs in drug-resistant cells by reducing the content of ATP and inhibiting the transport function of P-gp, which is expected to alleviate the multi-drug resistance of cells mediated by P-gp. This study indicated that quercitrin metal complexes, Cu-Quercitrin, were expected to be a novel P-gp inhibitor. At the same time, metal complexes with diverse structures and abundant ligands were expected to be candidate compounds for effective P-gp inhibitors. [Abstract](96) [FullText HTML](71) [PDF 1274KB](0) Abstract: Silica nanocapsules were synthesized in miniemulsion by using the surface of miniemulsion droplets as a template for the hydrolysis and condensation of tetraethoxysilane. In this study, we successfully used gemini emulsifier Octenidine·2HCl (OCT) to encapsulate tea tree oil (TTO) in the core of Silica nanocapsules (SINC-OCT/TTO). Then, we synthesised the silica nanocapsule (SINC-TTO) in the same way which was only the OCT was replaced with another emulsifier Cetyltrimethylammonium Chloride (CTAC). we compared the SINC-OCT/TTO with SINC-TTO in the structure and properties. Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were used to characterize the structure of the nanocapsules. The specific surface areas and pore size of the SINCs were characterized with N2 absorption-desorption. The hydrodynamic diameter of the capsules was evaluated by Dynamic light scattering(DLS). The results show that the content of tea tree oil loaded in SINCs, hydrodynamic diameter, specific surface area and pore size of SINCs are controlled by the type of surfactant. The hydrodynamic diameter of the two kinds of nanocapsules are 67.36 nm and 121.7 nm and the specific surface areas are 289 and 437 m2/g respectively. The content of tea tree oil in SINC-OCT /TTO (47.7%) is higher than the content of tea tree oil in SINC-TTO (33.3%). The results of fractional inhibitory concentration index showed that TTO combined with OCT has synergistic antibacterial effect on Staphylococcus aureus and has accumulative antibacterial effect on E. coli. The antibacterial experiment results of nanocapsules confirmed the antibacterial effect of SINC-OCT/TTO is much higher than that of SINC-TTO. [Abstract](127) [FullText HTML](55) [PDF 1268KB](0) Abstract: Metal-organic Frameworks (MOFs) is a new series of porous materials with some impressing physical and chemical properties, which give MOFs great potential in catalyst and separation. In this work, we prepared PV membranes with MOF, CNT and PVA, and apply the membranes to PV operations for separating ethanol and isopropanol water solutions. The result shows that, MOFs and CNT can efficiently change the structure and property of PVA PV-membranes. The permeation flux of the PV-membranes increases and the separation selectivity falls when the amount of MOFs increases. However, when the amount of CNT increases, they can't disperse evenly in the solutions and have a strong tendency to assemble together, thus leads to a somehow poor separation property. With proper CNT and MOF amounts, we can get a PV-membrane with ideal property. [Abstract](77) [FullText HTML](55) [PDF 2843KB](1) Abstract: The medium-temperature or low-temperature alkaline leaching method of spodumene ore is an environmentally friendly laboratory technology being explored. The low concentration of lithium and high concentration of impurity ions in the leaching solution make it impossible to prepare lithium carbonate. Herein, the preparation of low-solubility and high-value lithium phosphate (\begin{document}${\rm{L}}{{\rm{i}}_{\rm{3}}}{\rm{P}}{{\rm{O}}_{\rm{4}}}$\end{document}) is proposed. The solubility of \begin{document}${\rm{L}}{{\rm{i}}_{\rm{3}}}{\rm{P}}{{\rm{O}}_{\rm{4}}}$\end{document} in alkaline solution system was determined. The effect of process conditions on the yield and particle size of \begin{document}${\rm{L}}{{\rm{i}}_{\rm{3}}}{\rm{P}}{{\rm{O}}_{\rm{4}}}$\end{document} was investigated, as well as the influences of impurity ions, including K, Si, Al on the purity, morphology and size of \begin{document}${\rm{L}}{{\rm{i}}_{\rm{3}}}{\rm{P}}{{\rm{O}}_{\rm{4}}}$\end{document}. The mechanism study indicates that the synergy of ion-selective-adsorption on the crystal surface and ion-intercalation in the crystal lattice are responsible for the effects. Central composite design (CCD), a kind of response surface methodology, was employed to explore the effects of reaction temperature, lithium concentration, dosage of sodium phosphate and feeding rate. The optimal conditions were determined to be 80 ℃, 1.60 g/L, 130% and 10 mL·min−1, respectively. Under the conditions, the optimal yield and the average particle size were predicted to be 97.37% and 18.57 μm, respectively, while the corresponding experimental results were 96.85% and 18.70 μm, respectively. The errors between the predicted and experimental values were small. [Abstract](92) [FullText HTML](71) [PDF 882KB](0) Abstract: Glucose oxidase (Glucose oxidase, GOD) is widely used in food, chemistry, medicine, biotechnology and other industrial applications. In this study, the GOD gene from Aspergillus niger was optimized according to the codon bias of P. pastoris, then used to construct the GOD secretory expression vector pPIC9K-GOD and the corresponding recombinant P. pastoris strain G/GOD. Subsequently, the higher concentration of geneticin (G418) was used to select the multicopy genomic integration strain G/GODM, and the extracellular GOD specific activity was improved to 5843.2 U/g·DCW, which was 8.2-fold that of the single copy strain G/GOD. On the basis of this first generation high producing strain, additional co-expression of folding factors, as well as the enhancement of central carbon metabolism, was tried to construct the second generation strain. Co-expression of the protein folding factors PDI1, PDI2 and HAC1 improved the extracellular GOD activity by 32.7%, 8.9% and 54.4%, respectively. With the co-expression of the pentose phosphate pathway gene SOL3 and the tricarboxylic acid cycle gene MDH1, the extracellular GOD activity was enhanced by 6.3% and 11.6%, respectively. The best strain G/GMH1 was selected for the bioreactor fermentation to achieve 6656.6 U/g·DCW of the extracellular GOD activity in a 50-L bioreactor, indicating its value for industrial application. [Abstract](1735) [FullText HTML](389) [PDF 1155KB](3) Abstract: Blade-type multiply circular gas jets can be utilized for intensive cooling within limited area.The effects of impingement height H and jet Reynolds numbers on the heat transfer when multiply intensive circular air jets normally impinge on a smooth and flat surface are investigated experimentally. The average convective heat transfer coefficients are measured with heated thin foil technique which involves the detection of surface temperature and apples const heat flux heating. The jet Reynolds numbers ReD, vary from 5 000 to 48 500 and normalized impingement height H/D is in range of 6.25 to 12.5. The experimental results show that an increase in jet Reynolds numbers will produce higher average Nusselt numbers and normalized impingement height with an exponent of −0.606 also have a strong impact on it. The experiment findings are compared with Martin’s correlation and about 40% higher is observed. It is indicated that intensive circular nozzle array can significantly enhance heat transfer rate due to its high open porosity. The experimental data are quite well fitted by the Gardon's equation. Conversely the correlation proposed by Martin is not suitable to reduce present data and a modified geometrical function is developed. [Abstract](98) [FullText HTML](55) [PDF 998KB](0) Abstract: Based on the 12-lumped kinetic model established in the laboratory for residue fluid catalytic cracking (RFCC), an industrial reactor model for RFCC was established by setting unit factors and recycle calculation. An industrial simulation software of the model for unit factors calculation and product distribution prediction was developed. Based on the kinetic parameters from the laboratory model and steady operation data from an industrial unit, the unit factors were calculated by combining the fourth order Runge-Kutta method and the BFGS optimization algorithm. It is proved that the relative errors between the predicted yields and the actual yields of the products are mostly within 5%, which indicates the reliability of the industrial reactor model established for RFCC and the unit factors. The effect of reaction temperature and catalyst to oil ratio on product yields was also investigated. The prediction of product distribution trend by the software is consistent with catalytic cracking reaction rules, indicating that the reliability and extrapolation of the model are good and laying a good foundation for the further industrial application of the model. [Abstract](119) [FullText HTML](55) [PDF 856KB](0) Abstract: Pd/C catalyst was applied to the reaction of hydrogenation of phenol to cyclohexanone. After comparing the dichloromethane, cyclohexane, ethanol, and benzene, benzene was selected as the solvent. The effects of reaction conditions such as temperature, pressure, molar ratio of hydrogen to phenol, and phenol mass space velocity on the hydrogenation of phenol were investigated by controlling variables. A fixed bed tubular reactor was charged with 80-100 mesh Pd/C catalyst. 25 groups of experimental data were measured by changing the temperature, pressure and molar ratio of hydrogen to phenol. A intrinsic kinetic model was established on the ideal adsorption model and the parameters were estimated using 25 sets of orthogonal experimental data, and the dynamics model was tested. The results show that the suitable reaction conditions are: reaction temperature 175 ~ 205 ℃, reaction pressure 0.1 MPa, n(H2)/n(phenol) 4, and the weight hourly space velocity of phenol 0.2 ~ 0.4 h-1. After inspection, the established intrinsic kinetic model has good reliability. [Abstract](2075) [FullText HTML](779) [PDF 950KB](15) Abstract: Aiming at the shortcoming that there exist too many channels in motor imagery (MI)-based brain-computer interface (BCI) systems, this paper proposes a channel selection algorithm based on multi-correlation forward searching (MCFS) algorithm such that the performance of BCI systems can be improved via the optimized the channel set. First, a forward searching algorithm is performed on the channel set via the training set. Meanwhile, the trust values of three correlation algorithms are updated with the classification accuracy of the validating set. Then, according to the above trust values, the high-quality channel set is selected, the common spatial pattern (CSP) algorithm is adopted to obtain the motor imagery related features, and the classification model is trained by means of support vector machine (SVM) with a linear kernel. Finally, the proposed algorithm is implemented on two datasets (BCI competition IV dataset I and BCI competition III datasets IVa), by which the average classification accuracy 81% and 87% are achieved, respectively. Moreover, compared with three other common channel selection algorithms, the proposed MCFS algorithm obtains the highest average classification accuracy. These results show that the proposed MCFS algorithm has superior performance and provides a technical reference for the application of MI-based BCI system. . [Abstract](2072) [FullText HTML](833) [PDF 1011KB](50) Abstract: Hypervolume-based evolutionary algorithms can effectively solve the multi-objective optimization problem and obtain promising solution sets with fast convergence and uniform distribution. However, this kind of algorithms have higher computational complexity and lower programming efficiency. Aiming at the two-dimensional and three-dimensional multi-objective optimization problems, this paper proposes a hypervolume-based multi-objective evolutionary algorithm (MOEA-HV) so that the individuals’ exclusive hypervolume contributions can be accurately calculated to guide the evolution of the whole population. Before the indicator-based evolutionary algorithm(IBEA) is utilized, the proposed algorithm employs non-dominated sorting among all individuals to delete dominated individuals so that the amount of calculation of the individuals’ exclusive hypervolume contributions can be reduced and the operational efficiency can be improved. Meanwhile, other strategies in NSGA-Ⅲ are utilized to optimize the distribution of the proposed algorithm. It is shown via the experiment results that the proposed MOEA-HV has higher efficiency while maintaining the trade-off between the fast convergence and the uniform distribution.. [Abstract](106) [FullText HTML](59) [PDF 663KB](0) Abstract: The emulsified asphalt products have many disadvantages used as shale inhibitors for drilling fluid, such as high colloid content, poor stability, serious pollution, poor dispersion and poor anti-collapse. In this work, a C9 petroleum resin and an aromatic oil are used as the main blending raw materials. The preparation procedure is similar to the conventional preparation method of asphaltic-type shale stabilizer. After the sequential steps of blending, emulsification, and stabilization, a new type petroleum resin shale inhibitor (PRSI) was obtained. Results showed that the PRSI could inhibit shale swelling, dispersion, and reduce the filtration loss. In addition, PRSI has good compatibility with other additives and does not affect the rheological properties of drilling fluid. When the dosage is 2wt.%, it reduces the water loss of drilling fluid by 18wt.%, and the relative reduction rate of core expansion is 8% higher than that of the emulsified asphalt. As a shale stabilizer, it has a good application prospect in oil and gas drilling. [Abstract](104) [FullText HTML](59) [PDF 919KB](1) Abstract: Coenzyme Q10 is an important hydrogen transmitter in respiratory chain, which plays an important role in human body. It has been widely used in the treatment of cardiovascular and cerebrovascular diseases, and has been applied in cosmetics, health care products and other aspects. With the development of research, the market demand and industrial output of coenzyme Q10 are constantly expanding. Microbial fermentation is the most promising method for the production of coenzyme Q10. This study used atmospheric and room temperature plasma (ARTP) towards Rhodobacter sphaeroides to obtain mutants. Meanwhile, an oxygen-limited model was established to screen the strains which could suffer the low oxygen concentration. The bacterial suspension was treated by ARTP for 25 s, then cultured on the plate with 0.4 g/L sodium sulfite. The strains were fermented in 2 mL volume for 48 h. In the primary screening 24-well plates, 6 mutants were obtained. Furthermore, these mutants were cultured in shake flask to verify genetic stability. A mutant R. sphaeroides F5D13 performed good stability and production of Coenzyme Q10.The titer of R. sphaeroides F5D13 was improved from 86.2 mg/L to 111.8 mg/L compared to the original strain. Finally, the yield of Coenzyme Q10 reached 770.1 mg/L in 5 L fermentation after 100 h, which was increased by18.0%. According to the fermentation parameters, the mutant R. sphaeroides F5D13 showed the advantage of biomass in the cell growth phase and strong oxygen demand in product synthesis phase, which leaded to the higher oxygen uptake rate and yield than the original parent strain. [Abstract](1830) [FullText HTML](435) [PDF 792KB](2) Abstract: By using the hyphenated instrument of solid phase extraction (SPE) and solid phase spectroscopy developed by our group, a rapid, sensitive and selective method for detecting Hg2+ in river was proposed. A orange Hg-Dithizone compound was produced with dithizone and the analyte Hg2+ in solution, and then was enriched on the mixed cellulose membrane, the extra dithizone was removed by washing the membrane with sodium hydroxide solution, after that a visible diffuse reflectance spectrum was measured on the membrane directly for the quantitative analysis of mercury. In this work, the serious interference problems were resolved by using base washing to remove dithizone and by adding EDTA to mask Cu2+ and Cd2+. Under the optimal conditions, the liner range of the method was 0.5-30 μg/L with a squared correlation coefficient of 0.993, and the limit of detection was 0.444 μg/L. The method was applied to the detection of Hg2+ in river samples. The recoveries were from 91.3%~108%, and the relative standard deviations of parallel tests were between 2.06% and 9.68%. This work provided a fast method for the determination of Hg2+ in river samples with high sensitivity and selectivity, as well as acceptable accuracy and precision. [Abstract](104) [FullText HTML](60) [PDF 900KB](0) Abstract: A hydrophobic coating was prepared via a simple NaCl-dissolution-assisted etching silicon template method. And epoxy resins, with excellent properties, were selected as the matrix. The effect of sodium chloride concentration and spraying times on the microstructure and wetting properties of the coatings were studied. The results show that a multi-stepped rough structure formed gradually with the increase of salt concentration and the spray times. After using saturated salt solution spraying 30 times, the water contact angle (WCA) of the surface increases from 80.2° to 130.0°, indicating its good hydrophobicity. Besides, the coating shows superior abrasion resistance and chemical stability for strong acid and alkali solutions. Even after 50 times of abrasion test, the hydrophobicity of the surface hardly changed. Furthermore, the morphology of the prepared porous silicone template retains well after 20 casting and demoulding cycles, indicating its excellent reusable performance. [Abstract](122) [FullText HTML](61) [PDF 947KB](0) Abstract: Porous carbon derived from wasted cigarette filters (WCFs) were synthesized using an atmospheric-pressure chemical vapor deposition, using KOH as activator at 500-700 ℃. Brunauer-Emmol/Lett-Teller test showed that the surface area of porous carbon derived from WCFs increased with activation temperature. Micro- and meso-porous carbon (MMOL/LC) derived from WCFs at 700 ℃ (MMOL/LC700) exhibited a micro-pore dominant structure (pore size <2 nm), with a surface area of 928 m2/g. MMOL/LC700 powder was made into electrodes for capacitive deionization and, with an initial NaCl concentration of 5 mmol/L, the MMOL/LC700 electrode showed an ion adsorption capacity of 8.66 mg/g upon a bias of 1.2 V. MMOL/LC700 showed a carbon yield of 4.9% from its original WCFs. XPS showed that MMOL/LC700 contains a carbon content of 92.87%. 700 ℃ is a relative low activation temperature which provides a low vapor pression of KOH, benefiting the environment. This work suggests a facile method of converting WCFs into porous carbon, and its application in water desalination based on capacitive deionization. [Abstract](125) [FullText HTML](57) [PDF 771KB](2) Abstract: In order to improve the accuracy of personalized film and television recommendation, a hybrid recommendation algorithm CAMF-CM is proposed, which combines a decision tree model and a matrix decomposition algorithm containing user context information. A matrix decomposition algorithm that incorporates context preferences is used to obtain the initial movie recommendation list TOP-N. Then, a decision tree algorithm is used to perform feature label training on the context data set Ldos-Comoda to obtain the user's movie preferences in a given context. According to the TOP-N recommendation results obtained previously, the user's selection tendency in a given context is collected by the decision tree model, and the TOP-N list is filtered again to obtain the final TOP-N recommendation list. The method of verifying the efficiency of the algorithm is a ten-fold cross-validation method, which calculates the MAE mean of the collaborative filtering algorithm, the basic matrix decomposition algorithm, the Baseline prediction algorithm, and the CAMF-CM hybrid algorithm. The final result is obtained by comparing the size of the MAE mean. This method can solve the problem of the lack of interpretability of the results obtained by the traditional matrix factorization algorithm, and it can also solve the problem that the traditional recommendation algorithm does not consider the situation. After a comparative selection of decision tree models in the context data set LDOS-CoMoDa, compared with user-based collaborative filtering algorithms, basic matrix decomposition algorithms, and Baseline recommendation algorithms, the CAMF-CM recommendation algorithm has higher accuracy. [Abstract](142) [FullText HTML](72) [PDF 793KB](1) Abstract: Sign language recognition technology based on computer vision brings great convenience to bilingual teaching in deaf schools, and one of the challenges of sign language recognition technology is to extract keyframes of the video. Based on the characteristics of key frames of sign language video and the signing habits of sign language speakers, this paper proposes a video key frame extraction and optimization algorithm for sign language recognition. Firstly, the convolutional auto-encoder is used to extract the deep features of video frames, which are clustered by K-means. Among each group of video frames, the clearest video frames are selected as firstly extracted keyframes by definition. Secondly, the point density method is used to optimize the extracted keyframes, and then the final key frames are obtained for gesture recognition. The experimental results show that the algorithm could reduce substantial redundant frames, and improve the accuracy and efficiency of sign language recognition. [Abstract](92) [FullText HTML](67) [PDF 1186KB](2) Abstract: With the advent of depth camera such as Microsoft Kinect, the method of recognizing human action using 3D skeleton node data with it’s simplicity, robustness and view-independent representation has achieved quite good performance. But the representations of skeleton sequences learned by most of the existing methods lack spatial structure information and detailed temporal dynamics features. Therefore, the BI-LSTM model the characteristics of long-term storage of skeleton sequences is used in this paper to obtain rich bidirectional time information and model the sequence of actions. And at the same time, the relative distance features and angle features between joint points extract from 3D bone joint point coordinates to strengthen the spatial structure features and complete the recognition of human action from the skeletal data. The results show that this method effectively classifies human actions and improves accuracy. [Abstract](417) [FullText HTML](158) [PDF 1144KB](2) Abstract: How to characterize the cross-section quality after blanking test is a difficult problem in the punching industrial field. At present, the main evaluation method for the cross-section quality is to measure the relative ratio of smooth-sheared length and fracture length. However, the relative length ratio can’t reveal the complexity of the fracture surface and can’t fully characterize the details of the cross section profile. As a promising theory, fractal theory has been widely used in the metal research field and has a great advantage on the quantitative characterization of the quality of blanking cross sections. Based on the Mandelbrot fractal theory, the relative length ratios of different blanking cross sections were measured and the fractal dimension of each fracture surface were calculated. The research found that with the decrease of the fractal dimensions of the blanking cross section, the quality of fracture surface becomes better. The numerical simulations of the blanking process show that the smooth fracture zone is determined by the shear stress, and the fracture zone is determined by the tensile stress. The study results showed that the upper limit of fractal dimension for the blanking section can be estimated by measuring the fractal dimension of the fracture profile of tensile specimen. [Abstract](6865) [FullText HTML](1496) [PDF 1486KB](7) Abstract: Abstract: Halogen-free surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium alkyl sulfate ([C4mim][C12SO4]), was synthesized through ion exchange reaction. The photo responsive system of Gemini12-3-12/[C4mim][C12SO4]/ trans -OMCA/H2O was constructed by mixing [C4mim][C12SO4] with Gemini surfactant 12-3-12·2Br- (Gemini12-3-12), followed by an addition of photosensitive molecules, trans -o-methoxy cinnamate ( trans -OMCA). The photo-responsive behaviors of aqueous two-phase system (ATPS), a specific single-phase system and the anisotropic phase system in the mixture of Gemini12-3-12/[C4mim][C12SO4]/ trans -OMCA/H2O mixed system are studied by TEM, UV-vis and dynamic light scattering (DLS). The results show that the mixed system displays good photo responsiveness. For the aqueous two-phase system, in which spherical micelle and wormlike micelle coexist, UV irradiation for a certain period of time promotes the fusion of the spherical-micelle phase and wormlike-micelle phase into another single wormlike-micelle phase. For the single-phase vesicle system, it is separated into a two-phase system of spherical micelle and wormlike micelle after UV irradiation, and the system gradually merges into a single wormlike-micelle phase when the irradiation time is prolonged. The anisotropic system becomes isotropic after exposure to UV irradiation. It is suggested that the macro-phase behaviors of the system can be tuned by UV irradiation and the system could undergo a photo-induced phase separation as well as combination. [Abstract](558) [FullText HTML](191) [PDF 832KB](1) Abstract: A Mach-Zehnder interferometer demodulation scheme based on slow light in electromagnetically induced transparency medium is proposed and applied to improve the sensing sensitivity of fiber Bragg grating strain sensors. Theoretical studies have found that higher group refractive index can be obtained under suitable control field conditions by the common Λ-type three-level atomic system, and the sensing sensitivity of fiber Bragg grating strain sensors is improved. Influences of the control field on the sensing range and sensing sensitivity are further analyzed. According to the theoretical calculation, when the control field G=60 MHz, the sensitivity of fiber Bragg grating strain sensor based on Mach-Zehnder interference demodulation can be increased by about 3000 times. The proposed strain sensor demonstrates a high sensitivity of −40 Rad/uε and strain measurement range of −50~50 nε. [Abstract](6307) [FullText HTML](1719) [PDF 1389KB](15) Abstract: To explore the relationship between drug grafting ratio of polymeric prodrugs and their drug-loading efficiency, a model polymeric prodrug: methoxy poly(ethylene glycol)- b -poly(ε-caprolactone- co -piperilactone- g -5-aminolevulinic acid) (mPEG- b -P(CL- co -APIL)) was prepared. This prodrug was used as a drug carrier of 5-aminolevulinic acid (5-ALA) through both covalent bonding and non-covalent embedding. Molecular dynamics (MD) was used to calculate the compatibility of the polymeric prodrug with 5-ALA and H2O molecules, and to predict the relationship between the drug grafting ratio and drug loading. On calculation, the Flory-Huggins interactional parameter was decomposed into van der Waals force components and electrostatic force components for analysis of the effect of 5-ALA grafting ratio on the polymeric prodrug carrier. Dissipative particle dynamics simulation (DPD) was used to explore and observe the morphology of the drug-loaded micelles and the concentration state of the drug molecules. Computational simulation results showed that the compatibility between polymeric prodrug and 5-ALA improved with an increasing drug grafting ratio, leading to a prediction that the drug loading efficiency of polymeric drug would improve as the drug grafting ratio increased. Meanwhile, the DPD simulation showed that the polymeric prodrug self-assembles into spherical micelles in H2O.The density distribution of drug molecules suggested that the drug concentration in the core of the micelle was higher because of a higher drug grafting ratio. All the simulation results suggested the feasibility of improving drug loading efficiency by drug-molecule grafting. This research offers guidance for the design and development of drug carriers. [Abstract](475) [FullText HTML](170) [PDF 957KB](2) Abstract: Poria cocos, known as FuLing in Chinese, is a traditional Chinese medicinal herb. Poria cocos polysaccharides (PCPs) were extracted by water extraction and alcohol precipitation method from P. cocos collected from different origins. High performance liquid chromatography (HPLC) was applied to establish the fingerprint for 16 batches PCPs. A macrophage cell line Raw274.7 was incubated in the different concentration of 16 batches PCPs. The immunological activity was evaluated based on the proliferation activity of cells as determined by MTT assay and NO production. The immunological activity of 16 batches PCPs were introduced into orthogonal partial least squares analysis to investigate the correlation between monosaccharide compositions and immunological activity. The results showed that PCPs were composed of eight monosaccharides, including Glc, Gal, Man, Fuc, GlcN, GlcA, Xyl and Ara. The similarity analysis showed that the similarity of the 16 batches PCPs ranged from 0.981 to 1. All the 16 PCPs showed well immunological activities, according to the in vitro activity evaluations. Mouse macrophages were stimulated with different concentrations of PCPs. NO production increased with the increase of PCPs concentration, which was higher than that of the blank. According to the orthogonal partial least squares analysis, all the monosaccharides from PCPs had relationship with immunological activity. Gal, Ara, Man and Glc were positively correlated with the immunological activity of mouse macrophages. Fru, GlcA, GlcN and Xyl were negative correlated with the immunological activity of mouse macrophages. Particularly, Glc, Gal and Man in PCPs were significantly contributed to the NO production from mouse macrophages. [Abstract](6192) [FullText HTML](1648) [PDF 877KB](2) Abstract: Partial transfer sequence (PTS) is an effective method for filter bank multicarrier (FBMC) to reduce peak-to-average power ratio (PAPR). However, PTS method selects the optimal phase factor via exhaustive search, which inevitable results in high computational complexity. In order to overcome this shortcoming, this paper presents a new PTS-based method. Firstly, based on the traditional PTS segmentation method, this paper introduces an odd-partial transfer sequence(OPTS) segmentation method, which uses staggered segmentation for odd subblocks and random segmentation for even subblocks. By combining the advantages of staggered segmentation and random segmentation, this proposed method can effectively improve the PAPR performance of the system, meanwhile, reduces the computational complexity. Secondly, this paper proposes a scaled particle swarm optimization (SPSO) algorithm by incorporating the scaling factor into the traditional PSO algorithm. It is known that the conventional particle swarm optimization (PSO) algorithm has a slow convergence rate in the iteration process and is prone to fall into local optimal in high-dimensional space. Aiming at the above shortcoming, this paper proposed an improved PSO algorithm, SPSO algorithm, whose main idea is to use the scaling factor to control the particle speed, and obtain better PAPR performance with lower computational complexity and faster convergence speed. It will slightly increase PAPR value via integrating SPSO algorithm into OPTS and can attain better performance in terms of complexity, and significantly improve the spectrum utilization. Finally, simulation results verify the effectiveness of the new method. [Abstract](433) [FullText HTML](108) [PDF 793KB](1) Abstract: Stimulus-responsive molecular shuttles have unique shuttle movement capabilities in mechanically interlocked nanosystems, but how to choose appropriate and efficient control methods in a complex host-guest system has always been a difficult problem to be solved. Photochemical stimulation is considered to be the most promising and most valuable mode for regulating molecular machines, because light control is not only accurate in time and space, but also has the advantages of simplicity, cleanness and no pollution. Light-induced proton transfer is a novel regulation strategy that can be applied in the host-guest system of acid-base response. Based on the photo-induced proton transfer mechanism, a [2]rotaxane R molecular shuttle with photoacid (merocyanine, MEH) controlled response was successfully designed and synthesized, and its structure was confirmed by 1H-NMR, 13C-NMR and mass spectrometry. Before and after exposing to light, the UV absorption and 1H-NMR spectra of the system were compared by means of UV-Vis and variable-temperature 1H-NMR spectroscopy. The results showed that in the presence of photoacid (MEH), at 419 nm, the CBPQT4+ macrocycle was located on one side of the naphthalene, and the [2]rotaxane R molecular shuttle was in a "stationary" state; while in the dark for 12 h, the CBPQT4+ macrocycle shuttled between the two naphthalene components, and the [2]rotaxane R molecular shuttle was in a "moving" state. This work offers a strategy for conformational transmission in molecular level. [Abstract](336) [FullText HTML](96) [PDF 1232KB](1) Abstract: The associated fluorine impurities in phosphate ore seriously affect the quality of the phosphoric acid during the wet-process phosphoric acid production. Tributylphosphate (TBP) was used as an extractant, sulfonated kerosene (hereinafter referred to as kerosene), isoamylol, diisopropyl ether were used as the diluent, respectively. The extraction mechanism was investigated by quantum chemical calculation, flourier transform infrared spectroscopy (FT-IR), 19F nuclear magnetic resonance (19F-NMR) and composition of extraction complexes. The binding energy of TBP-kerosene with HF was calculated by implicit solvent model, while TBP-isoamylol and TBP-diisopropyl ether with HF were calculated by explicit solvent model. The results show that the binding energy of above three extraction systems are −13.399 kJ/mol, −19.199 kJ/mol, and −20.556 kJ/mol, respectively. Analyses of the FT-IR spectra of the loaded organic phases indicate the TBP extraction of HF is occurred by the association of hydrogen bonding, while the extraction of HF using isoamylol and dissopropyl ether is realized through hydrogen bonding. The main form of fluoride in organic solvent was TBPHF according to the 19F-NMR spectra. The compositions of the extraction complexes in the solvent of kerosene, isoamylol, diisopropyl ether were determined to be 0.9HF TBP, 1.4HF TBP and 1.6HF TBP, respectively. The effects of different fluorine forms in wet-process phosphoric acid on defluorination rate were studied. It can be concluded that CaF+ and \begin{document}${\rm{FeF}}_x^{3-x}$\end{document} (x=1—6) have a slight effect on the selectivity coefficient and defluorination rate. MgF+ can be effectively extracted from the organic solvent by TBP, and the selectivity coefficient is increased with increase in the concentration of Mg2+. The TBP extraction of \begin{document}${\rm{SiF}}_6^{2-}$\end{document} and \begin{document}${\rm{AlF}}_x^{3-x}$\end{document} were moderated, indicating that the defluorination of wet process phosphoric acid needs to be achieved by pretreatment or other methods when the content of active silica and aluminum oxide in phosphate rock is high. [Abstract](550) [FullText HTML](163) [PDF 1577KB](3) Abstract: The photocyclization quantum yield of traditional diarylethene systems is always limited to 50% (mol%) due to the inseparability of the parallel (p-) and anti-parallel (ap-) conformers. However, it is possible to block the conversion between the two conformers by increasing steric hindrance between the side aryl groups and ethene bridge, thus enhancing the photocyclization quantum yields. Herein, based on the sterically-hindered bisbenzo(thiadizole) ethene bridge, we fully compared the steric effect of side thiophene rings, and got insight into the electronic effects of substitution groups, like the electron-donating, such as anisole unit and the electron-withdrawing pyridine units. The parallel and antiparallel conformers of compounds 1 and 3 can be separated successfully upon introducing the sterically hindered methyl group to the β-position of thiophene rings, thus greatly improving their photocyclization quantum yields, higher than 50% (mol%). Moreover, the incorporated steric hindrance of β-methyl groups on thiophene rings results in lower thermal stability of 1c and 3c. In contrast, 2c and 4c show good thermal stability which can be attributed to the relatively small steric hindrance and intramolecular hydrogen bond. When compared with the electronic effects, the electron-withdrawing effects of pyridine units brings forth the higher thermal bleaching rate of 1c than that of 3c containing the electron-donating anisole units. [Abstract](355) [FullText HTML](153) [PDF 1385KB](2) Abstract: The magnetic polymer brushes contain a magnetic core and a polymer brush shell, which is a new type of core-shell structure composing of polymer chains densely grafted to the surface of the magnetic cores at one end. The magnetic core could be either based on single magnetic nanoparticle or composite materials, where the matrix to encapsulate the magnetic nanoparticles could be inorganic materials like silica or organic materials like polystyrene or poly(methyl methacrylate). The introduction of magnetic nanoparticles enables great convenience and functionality in the preparation process and practical application of polymer brushes. Functional magnetic polymer brushes could be recycled, separated, and purified by easy operation under external magnetic field. In the last decade, with the continuous development of preparation strategies of magnetic nanospheres and surface modification techniques of nanospheres, magnetic polymer brushes have been systematically studied on structure design, functionality and applications. Magnetic polymer brushes have broad application prospects in protein adsorption and purification, bioimaging, specific detection, and catalytic enhancement, etc. This paper reviews the latest research progress in magnetic polymer brushes and the future development direction is also anticipated. [Abstract](1963) [FullText HTML](629) [PDF 996KB](24) Abstract: Glutathione (GSH), one of the thiol short peptide in organisms, is widely used in medicine, food additive, health care and cosmetic industries. In this study, a two-enzyme cascade consisting of bifunctional glutathione synthetase (GshF) and polyphosphate kinase (PPK) was constructed for ATP-regenerating synthesis of GSH. As the catalytic substrate of PPK, polyphosphate (polyP) was used to provide energy in the reaction. The efficient soluble expressions of GshF and PPK were obtained when induced at the low temperature of 18 ℃. After purification, the two enzymes were coupled together to synthesize GSH in one pot. It was found that high concentration of MgCl2 inhibited the production of GSH due to the chelation with polyP. The optimal concentration ratio of polyP to MgCl2 was 30∶45 (mmol/L∶mmol/L). At 0.5 mmol/L ADP, the reaction achieved the highest efficiency for GSH synthesis. The optimal temperature for the two-enzyme reaction was 45 ℃, achieving a high yield of 78% based on added L-cysteine. The optimal temperature for GSH synthesis was relatively high, because the activities of GshF and PPK could increase with the increased temperature. The enzyme ratio in the system was further investigated. The production of GSH was improved at higher concentration of PPK, indicating the ATP-regenerating reaction was a limiting step in the reaction. At the optimal ratio of 4 g/L PPK and 1 g/L GshF, the titer of GSH reached 58 ± 3.3 mmol/L with a productivity of 19.3 ± 1.1 mmol/L/h at 3 h, which achieved the reported highest production of GSH. Using the low-cost substrate of polyP to supply energy, the efficient cascade reaction provided a potential application for large-scale enzymatic production of GSH. [Abstract](2361) [FullText HTML](741) [PDF 837KB](18) Abstract: The variable neighborhood search algorithm may difficulty search a better feasible solution in some neighborhoods in later stage for a long time. Aiming at the shortcoming, this paper proposes an adaptive variable neighborhood search algorithm based on neighborhood selection probability. The proposed algorithm can adjust the selection probability in some neighborhoods adaptively according to the optimization circumstance of this neighborhood such that the optimization efficiency can be improved. This paper designs two select probability update methods and analyzes their characteristics. By setting the minimum selection probability, the selection probability may be avoided to reduce to zero and the diversity of the neighborhood can be ensured. Due to battery capacity limitations and charging requirements, the optimization problem of the electric vehicle route is more complicated than the traditional vehicle route problem. By modeling and analyzing the large-scale electric vehicle routing problem under the actual urban distribution logistics, this paper proposed an efficient initial solution generation algorithm according to the geographic location and the time window of the service customer. Some neighborhood operators using segmentation-exchange, 2-opt, and relocation are designed to achieve the adaptive variable neighborhood search. Finally, the simulation experiments with different scales data are made. It is shown from the results that the variation curves of the two select probability update methods have the same tendency, which verifies the rationality of minimum selection probability vector setting. Compared with the traditional variable neighborhood search algorithm, the proposed adaptive variable neighborhood search algorithm can effectively jump out of the local optimal solution and reduce the logistical cost under urban distribution. [Abstract](146) [FullText HTML](96) [PDF 696KB](0) Abstract: Nanopore is a highly sensitive single-molecule detection technology, which researches the information of single molecule by capturing the ion current signal generated when the molecule traverses the nanopore. However, because the different capture rates of different molecules in the nanopore, the dataset collected is unbalanced, which affects the accuracy of the identification of molecules. Therefore, a Generative Adversarial Networks(GAN) is introduced in this paper. Based on the blockage events of the encoded DNA molecules, a model based on the Deep Convolutional Generative Adversarial Networks (DCGAN) is constructed to augment the minority samples to achieve the balanced processing of dataset. In addition, QuipuNet is used to identify the dataset before and after the balancing. The results show that the average classification accuracy of dataset augment by our method is 0.96, which is better than the original dataset of 0.92 and others. What’s more, the identification accuracy of barcode ‘100’ is increased from 0.82 to 0.96. This method extends the feasibility of encoded DNA molecules to balance the dataset and improve the identification accuracy. [Abstract](135) [FullText HTML](100) [PDF 926KB](1) Abstract: The performance of semantic segmentation systems using visible cameras usually reduces dramatically at night or in bad weather conditions, due to its susceptibility to the variable lights. Simultaneously using visible cameras and thermal IR sensors can alleviate this problem. Although there is some work that studied the semantic segmentation of RGB-IR images, few works attempted to improve the segmentation results by enhancing the discriminability of the fusion feature. Therefore, we propose a novel framework of multi-spectral image semantic segmentation based on the process of supervised feature fusion. Firstly, the independent feature fusion modules constitute a whole fusion branch in the semantic segmentation network, so that the fusion of high-level features can guide the fusion of lower-level features. Then, the segmentation supervision signal is directly applied to the end of the fusion branch to improve the discriminability of the fusion feature and the convergence speed of the network. Finally, a dice loss instead of the cycle loss is used as the supervision of fusion branch to improve the segmentation of small objects, which along with the cycle loss on segmentation branch leads to a hybrid supervision. The experimental results on two multi-spectral datasets show that, compared with other multi-spectral semantic segmentation methods, the proposed method can achieve better segmentation results and is more advantageous for small objects segmentation. [Abstract](138) [FullText HTML](73) [PDF 782KB](0) Abstract: Aiming at the tracking failure caused by camera jitter or low-texture environment in slam, and for the task of 3D map reconstruction, a hybrid slam method R-ORB slam for depth camera is proposed in this paper. A pose estimation method based on photometric error is used as the prior of the feature-basedodometer, and the result of the method is used to participate in pose estimation in the case of ORB-SLAM2 tracking fail. At the same time, for generating dense three-dimensional point map with non-redundant points, a filter is used for down sampling of the global point cloud map obtained by fusion all point clouds of each key frame. Then, by using Poisson algorithm to reconstruct the surface of 3D point cloud map, the 3D map model is generated. Experiments on two popular open datasets show that the proposed method can effectively solve the problem of tracking failure and realize 3D reconstruction with high tracking accuracy and reconstruction accuracy. [Abstract](119) [FullText HTML](84) [PDF 932KB](1) Abstract: The global optimization problem has been widely used in various fields, but the traditional method relies on the gradient information of the objective function too much. The meta heuristic search algorithms have better flexibility and it can be used to solve practical problems. Hence, a ice crystal continuous optimization algorithm based on reinforcement learning and angle penalty distance (APD-CEO), which introduces probabilistic update strategy based on reinforcement learning and deviation strategy based on angle penalty distance, is proposed for the global continuous optimization problem. Firstly, ice crystal continuous optimization algorithm is proposed to solve the continuous extremum problem by simulating the freezing process of lake water. Secondly, in order to eliminate the error in calculating the energy from the temporary center of the lake, the Angle penalty distance strategy is introduced, and the convergence and diversity are better balanced. Meanwhile, probabilistic update strategy based on reinforcement learning can better guide the position of the newly formed crystals, accelerate the freezing process of the lake, and approach the center of lake faster (the global optimum). Finally, in order to verify the validity of probabilistic update strategy and angle penalty distance strategy, the algorithm before and after joining the strategy are compared. Moreover, APD-CEO has better performance than other algorithms in most benchmark functions, and the contrast effect is more obvious in the high dimensions. And Friedman test also shows that the APD-CEO ranks better among the five algorithms. [Abstract](150) [FullText HTML](83) [PDF 689KB](3) Abstract: Cover song identification is a relevant task in music information retrieval (MIR). To improve the cover song identification performance, recently, some researchers have proposed the song identification scheme based on non-linear graph fusion and tensor product graphs (TPGs) diffusion. It reduces the influence of noise mainly by learning the geometry structure of similarity high dimensional space. However, the model has the following aspects to be improved. First, the audio features introduced in the paper, such as harmonic pitch class profile (HPCP), main melody (MLD) and beat-synchronous chroma (BSC) are all the hand-crafting ones, and it is difficult to convey the nonlinear structure of music. Second, the algorithm only considers the audio content, and ignores the importance of lyrics information in cover song identification. Third, learning the geometry structure of similarity high dimensional space enhances the performance, and increases the computation complexity. To solve these problems, we propose a cover song identification algorithm based on the audio content and the lyrics text. To extract the high-level audio features, the deep pitch class profile (DPCP) scheme is introduced to analyze the audio content. To extract the contextual semantics and the term frequency in song lyrics, the bi-directional long short-term memory (BiLSTM) architecture and TF·IDF scheme are adopted, respectively. Finally, both the audio similarity and the similarity of lyrics are fused by the similarity network fusion (SNF) algorithm to get the final similarity. To verify the effectiveness of the algorithm, the Covers2326 dataset is constructed. The experimental results show that compared with the existing algorithm, the proposed one not only improves the identification accuracy but also improves the computational speed. [Abstract](98) [FullText HTML](86) [PDF 959KB](2) Abstract: Aiming at the problem of performance degradation after the upgrade of telecommunication systems, a Cross Correlation Function-Partial Least Squares (CCF-PLS) method is proposed to monitor the system's performance and find the root cause which leads to the degradation at the same time. A PLS model can establish a regression model between key performance indicator (KPI) and other observations with regard to those systems whose sampling interval is large and linearity is strong. Although there are many uncorrelated components between KPI and observations, CCF can choose those components with great correlations and can thus constitute a pre-processing procedure for PLS. Furthermore, the CCF-PLS method can provide the root cause in combination with contribution plots. As the simulation results show, the method proposed in this paper has good application effect. [Abstract](141) [FullText HTML](101) [PDF 1034KB](0) Abstract: For multi-object tracking in complex scenes, there are problems of high object identification switching rate and high object trajectory false alarm rate. This paper proposes a multi-object tracking algorithm based on pedestrian re-identification network and CNN-GRU (Convolutional Neural Networks-Gated Recurrent Unit) metric network. By constructing a deep metric model combining CNN and dual GRU network, the time characteristics of appearance and motion features of the tracking object trajectory boxes are predicted simultaneously, so that the object has more discriminative features and the ID switch rate of object is reduced. Based on the CNN-GRU network, the correct matching probability of historical object trajectory is automatically learned. Different attentions are assigned to different track trajectory boxes of the same object, so as to suppress the influence of misdetected object boxes in the object trajectory on the overall features of the object and effectively aggregate the features of the object trajectory box. The algorithm combines the similarity of detection boxes and trajectory boxes calculated by the features of pedestrian re-identification network, and the similarity CNN-GRU network output as the matching cost of data association part. The experimental evaluation results on a standard multi-object tracking dataset show the effectiveness of the proposed algorithm. [Abstract](168) [FullText HTML](98) [PDF 751KB](2) Abstract: The process of traffic signal control can be abstracted as a typical network control system. Network control systems have been extensively applied in many fields for its easy maintenance and installation. However, there are still some problems to be take care in practical analysis and design, such as network delay, packet loss, signal quantization and multi-packet transmission. Thus, the performance of the control system might decrease, which further leads to system instability. Dealing with these problems can help to promote its application. This paper presents an adaptive event-triggered model predictive control strategy to reduce communication consumption of networked control systems. The resulting framework is used for the stabilization of uncertain NCSs subject to quantization adaptive state transmission. The system state and the predictive control law are sent by wireless network only when the triggering conditions are satisfied, where the adaptive triggering mechanism has more flexible and better performance. The adaptive triggering parameter decides how often to transmit the current sample data. Under this mechanism, a robust MPC is designed to ensure the closed-loop stability of NCS with quantized effects and achieve the desired control performance, which can reduce the energy consumption and improve the network congestion. An algorithm implementation of this method is given in the paper. Finally, an example is given to illustrate the effectiveness of the proposed results. The result shows that triggering parameter can save more communication resources on the basis of event-triggered mechanism. The proposed event-triggered model predictive control method can ensure the robust stability of the system. [Abstract](131) [FullText HTML](91) [PDF 1101KB](1) Abstract: The airport perimeter intrusion alarm system is the first line of defense in the airport's flight zone. Traditional airport perimeter intrusion alarm system has high false alarm rate and inability to classify different intrusion categories under the influence of severe weather. In order to solve the problem, an auto encoder long short term memory network model was proposed. The model extracted hidden encoder feature from input signals and constructed feature vector matrix fused with timing information to reduce the complexity of the model. The results of network model performance evaluation show that the network model has a low false alarm rate as well as a high accuracy of vibration states classification. Besides, the network model has a low complexity which guarantees a good practical application prospect. , doi: 10.14133/j.cnki.1008-9357 [Abstract](128) [FullText HTML](83) [PDF 647KB](1) Abstract: The definition of single elements was first given by Erdos, though the notion itself was used earlier by operator theorist Ringrose. It is easy to show that every rank one operator is a single element of any algebra containing it. Since the single elements play a role in the representation theory of C*-algebras and Banach algebras, several authors study the property of single elements. Erdos proved that there exists a faithful representation of any C*-algebra into the (bounded) operators on a Hilbert space in such a way that single elements are carried to operators of rank one. Ringrose investigated certain kinds of nest algebras and showed that in them a nonzero element is single if and only if it is a rank one operator. Since single elements are carried to single elements under algebraic isomorphisms, Ringrose also proved that algebraic isomorphisms between certain nest algebras are spatial. The purpose of this article is to study the linear span of the single elements in the tensor algebras of directed graphs. The notion of ‘single element’ may prove to be useful in other fields. Let \begin{document}${{ G}_n}$\end{document} be the graph consisting of a single vertex \begin{document}$\{ p\} $\end{document} and n loop edges \begin{document}$\{ {e_1},{e_2}, \ldots {e_n}\} $\end{document} i.e., \begin{document}$s({e_i}) = r({e_i}) = p$\end{document}, \begin{document}$i = 1,2, \ldots n$\end{document}. We show every element of the tensor algebra \begin{document}${ T}_{{{ G}_n}}^ +$\end{document} is a single element. Moreover, every element of the free semigroupoid algebra \begin{document}${ L}_{{{ G}_n}}^{}$\end{document} is a single element. For a countable directed graph \begin{document}${ G}$\end{document}, We show the linear span of the single elements of the tensor algebra \begin{document}${ T}_{ G}^ +$\end{document} is dense in \begin{document}${ T}_{ G}^ +$\end{document}. For a finite directed graph \begin{document}${{ C}_n}$\end{document}, we show any element of \begin{document}${ T}_{{{ C}_n}}^ +$\end{document} is a linear span of \begin{document}${n^2}$\end{document} single elements of \begin{document}${ T}_{{{ C}_n}}^ +$\end{document}. [Abstract](359) [FullText HTML](109) [PDF 1166KB](0) Abstract: A strain CQ2, which can degrade the antibiotic cephalexin effectively, was separated from the sludge of domestic sewage treatment plant, and identified as Ochrobactrum sp. The strain was identified as gram-negative bacteria with a diameter of 4-6mm. Under 1000 times optical microscope, the CQ2 bacteria was rod-shaped with a size range of 0.4—0.6×1.2—2.5 microns. This strain could not efficiently degrade CX when the CX was the only organic carbon source, and could decompose CX rapidly in the presence of glucose, indicating that the bacteria removed CX through co-degradation mechanism. The effects of temperature, pH, rotating speed and inoculation amount on the growth and degradation efficiency of CQ2 were investigated by orthogonal test. The results showed that CQ2 could effectively degrade cephalexin, and the optimal cultivation conditions are 30 ℃, pH at 7.0, mixing rate of 150 rpm, and inoculation percentage of 5%. At the optimal condition, the cephalexin at initial concentration of 10 mg/L could be completely degraded within 28 h. Moreover, under the identical condition, the tested CQ2 bacteria could completely remove amoxicillin at 36 h, significantly degrade terramycin and sulfadiazine, but played a negligible role on the degradation of pefloxacin due to the inhibition on the CQ2 growth. It is possible that the chromosome of pale bacillus contains specific AmpC gene, which can produce the cephalosporin enzyme ApmC enzyme, and therefore has strong resistance to amoxicillin and cefalexin with the structure of β-lactam ring. Based on cephalexin degradation intermediates determined by LC-MS/MS, the biodegradation preliminary pathway of cephalexin by CQ2 was proposed, 2-hydroxyl-3-phenylpyrazine is the main intermediate of biodegradation after hydrolysis. [Abstract](368) [FullText HTML](99) [PDF 795KB](0) Abstract: Pattern dynamics is an important branch of nonlinear theoretical system. When Turing instability exist in the Belousov-Zhabotinsky (BZ) reaction, the system will generate Turing Pattern. Turing Pattern is a kind of stable and non-uniform spatial structure, which resulting from the Instability of the equilibrium solution of the reaction-diffusion equation caused by diffusion, and which are different from the chemical waves generated by the BZ reaction. Based on the classical Tyson model, the Turing instability analysis of BZ reaction was carried out in this paper, and the ranges of parameters of the system corresponding to the Turing Pattern were obtained. The calculated results were verified by numerical simulation, and the possible morphology of Turing Pattern in BZ reaction was also shown. In the work process, Routh-Hurwitz criterion was used to judge the stability of the equilibrium solution, and the ranges of parameters to make the equilibrium solution stable or unstable were obtained. The partial differential equation was transformed into the sum of several ordinary differential equations by Fourier expansion method. The finite difference method was used to simulate the BZ reaction, in this method the continuous region and functions were approximatively replaced by discrete region and functions. Through numerical simulation, not only the correctness of the calculated results were verified, but also the conclusion was obtained that the bigger the difference of two diffusion coefficient is, the faster the Turing pattern appears. BZ reaction is a simple reaction-diffusion system. The methods proposed and the results obtained from the study of BZ reaction provide a reference for the study of nonlinear systems including biological systems. [Abstract](358) [FullText HTML](95) [PDF 1136KB](0) Abstract: With the sewage treatment process becoming more and more complex, the proportion of easy-to-measure and hard-to-measure variables is seriously out of balance, so the traditional supervised soft-sensor modeling can no longer meet the demand. In order to solve this problem, this paper proposed a new soft-sensor model of semi-supervised tri-training MPLS. The labeled data were divided into three independent parts and the unlabeled data with high confidence would be selected from the three data set. Then, the model was trained to improve the predictive ability through new labeled data. In addition, the single-output model was upgraded to the multi-output model to directly predict multiple output variables. Finally, the model was verified by BSM1 platform (Benchmark Simulation Model-1). The results showed that the proposed soft sensor model has good prediction ability on multi-output prediction and satisfactory prediction on single target. [Abstract](416) [FullText HTML](155) [PDF 872KB](1) Abstract: Transparent superhydrophobic coatings have good potential applications in optical devices, solar panels, automobile windshields, glass building facade and so on. However, their real-world applications are still restricted by low transparency, poor durability, and complex preparation processes. Hybrid silica sol was prepared by sol-gel process using fumed silica, tetraethoxysilane (TEOS) and hexamethyl-disilazane (HDMS) as raw materials. The transparent superhydrophobic composite coatings were obtained via incorporating the hybrid silica sol and organosilicon oligomer which is synthesized with 2,3-Epoxypropoxy propyltrimethoxysilicane (KH560) and alkyl siloxane as precursors. The influence of amount of fumed silica and HDMS on the hydrophobic property of hybrid silica sol coatings was investigated, and the effect of the ratio of KH560, the kind of organosiloxanes and the amount of organosilicon oligomer on the properties of composite coatings was studied. The results show that the excellent performance of hybrid silica sol coatings could be obtained with the water contact angel (CA) of 166° and the sliding angel (SA) of less than 3° when m (fumed silica):m(TEOS)=0.075, m (HDMS):m (TEOS)=0.75. When the molar ratio of KH560 to MTES was 0.50:1, and m (organosilicon oligomer)∶m (hybrid silica) sol=0.100, the composite coating was still superhydrophobic and the water contact angle of the composite coating remained 138°even after 5 min ultrasonic treatment. The surface topography of the coatings was investigated by SEM. The SEM results directly indicated that the surface of composite coating displayed a continuous porous network, and a large amount of micro-nano composite rough structures were observed. Furthermore, the optical transmittance of the hybrid silica superhydrophobic composite coating was as high as 85.4% at 550 nm. [Abstract](346) [FullText HTML](122) [PDF 849KB](0) Abstract: In this paper the antibacterial activity of different ethanol extracts from Glycyrrhiza uralensis Fisch (G-EA) and Magnolia officinalis (M-EA) to Streptococcus mutans were tested and compared. The bacteriostatic effect, the effect on the activity of lactic dehydrogenase (LDH) and the effect on the restrain of biofilm of the two ethanol extract compound were explored as well. The antibacterial ability of the two ethanol extracts and compound were investigated through the testing of inhibition zone, minimal inhibit concentration (MIC) and fractional inhibitory concentration (FIC) and the results showed that the FIC between G-EA and M-EA for Streptococcus mutans was 0.375, which was less than 1 and possessed a synergistic effect. After the testing of MIC values of different mass ratios of G-EA and M-EA, the bacteriostatic effect was the best for the compound against Streptococcus mutans when the mixture ratio of G-EA and M-EA was 1:2, and the MIC of compound (G-M1:2) reached 0.32 g/L. According to the growth curve testing of Streptococcus mutans, the main bacteriostatic phase of G-M1:2 was its logarithmic growth phase and stationary phase and the bacteriostatic effect of G-M1:2 to Streptococcus mutans was superior to the tea polyphenol at the same concentration. The effect of G-M1:2 on lactic dehydrogenase (LDH) activity and biofilm formation in Streptococcus mutans was investigated. It turned out that G-M1:2 could effectively inhibit LDH activity and biofilm formation and the inhibition ability were enhanced with the increase in concentration. The test also indicated the minimum biofilm inhibition concentration 50% (MBIC50) of G-M1:2 was 0.08 g/L. [Abstract](366) [FullText HTML](99) [PDF 984KB](1) Abstract: To reduce the harm of cigarette smoke to health has been widely researched in the cigarette industry. The tobacco burning or heating mode has a great impact on the harmful components released. Much work has been done to develop the new cigarette-heat product to decrease the amount of the harmful components from the smoke. In order to investigate and understand the characteristics of tobacco heating by the cigarette-heat product, smoke flow state and heat transfer process during the smoking mode, a three dimensional mathematical model of porous medium for tobacco heating and smoke flow in a cigarette was established. The process of heat transfer and flow were numerically simulated using computational fluid method (CFD) software (ANSYS Fluent). The flied distribution of temperature, velocity and pressure during cigarette heating by the heater of cigarette-heat product and smoking at a constant flow rate were acquired. The results show that the tobacco could be effectively heated to 493.6 K by the heater for cigarette-heat product with a total heat transfer coefficient of 3.4 W/(m·K). During smoking at a constant flow rate of 17.5 mL/s, the tobacco temperature would decrease from 394.1 to 393.8 K with an uniform radial temperature distribution, and the smoke flow has a relatively small impact on temperature distribution of the tobacco. On the other hand, the pressure decreases from the tobacco section to holder. These results can provide the theory guidance and fundamental data for optimizing the structure of the cigarette-heat product and the heating mode of tobacco to a certain extent. [Abstract](359) [FullText HTML](102) [PDF 1412KB](3) Abstract: There are not only inorganic pollutants but also many organic pollutants in the water, which affects the ecosystem by its toxicity and reducing dissolved oxygen in the water. The adsorption separation method is one of the most widely used wastewater treatment methods because of its easy operation, low cost and recyclability. Cyclodextrin (CD) is a commonly used adsorbent material because of its encapsulating ability for hydrophobic molecules, but its water solubility and low adsorption capacity limites its application. Three different diisocyanates (hexamethylene diisocyanate HDI、1,4-Phenylene diisocyanate PDI、Diphenyl-methane-diisocyanate MDI) were selected as cross-linking agents to synthesize three CD-polyurethane composites (CD-HDI,CD-PDI,CD-MDI) with different structures. Then SEM, FT-IR, TG and UV-vis spectroscopy were employed to characterize the synthesized composites. The adsorption kinetic mechanism was studied by using pseudo-first-order model and pseudo-second-order model. The results showed that the pseudo-second-order model fitted better than the pseudo-first-order model, indicating that the adsorption of BPA and MB by the adsorbent is a chemisorption process. CD-PDI has the highest adsorption rate for BPA and MB, and the removal efficiencies of BPA and MB reaches 76% and 81% at 5 min. To study the adsorption mechanisms of CD-HDI, CD-PDI, CD-MDI toward different pollutants, three different models were applied to fit the equilibrium adsorption data. The results indicated that Sips model describe well the adsorption performance for BPA and MB and the maximum adsorption capacity was 65.3 mg/g~116.2 mg/g and 8.9 mg/g~26.5 mg/g, respectively. The removal efficiency of BPA and MB by the adsorbent decreased by 0.8%~2.4% and 7.6%~13.4% after 5 cycles, respectively, which proved that the adsorbent had good recyclability. [Abstract](370) [FullText HTML](115) [PDF 945KB](0) Abstract: Dispersion is an important indicator affecting the application properties of nano-silica. A new method for treating the precipitatednano-silica particles by high-temperature rapid flame treatment was proposed. The effect of the method on the surface structure and dispersion of silica nanoparticles was investigated. At the same time, the reinforcing effect on the silicone rubber was studied. The results showed that under the optimal treatment conditions, the mass fraction of adsorbed water of nanoparticles decreased by 28.3% compared with untreated samples, and the number of surface hydroxyl groups decreased by 27%. The treated nanoparticles were used for silicone rubber reinforcing filler. The tensile strength was increased by 41.6% compared to the untreated sample, and the tear strength was increased by 100%. [Abstract](429) [FullText HTML](147) [PDF 503KB](5) Abstract: New drug design is a huge project, and the failure rate is very high. If based on existing active compounds, the design of “me-too” drugs can increase the success rate. The “me-too” drug should have the same or similar spatial structure, pharmacophore, etc. as the original active compound, so as to ensure that the combination of the “me-too” drug and the enzyme is the same as the original active compound. The lead compound can provide the same or similar spatial structure as the original active compound, and a novel skeleton, but the skeleton of the lead compound does not necessarily have good physicochemical properties. Designing “me-too” drugs based on lead compounds can significantly reduce the difficulty of new drug development and improve development efficiency and success rate. How to accurately grasp the spatial structure of the lead compound, designing a novel structure, a reasonable valence bond, and a skeleton with the same or similar spatial structure as the lead compound are the key issues in designing “me-too” drugs. The author designs and writes an automated new drug skeleton design software based on the extraction of structural long chains, fragment matching and splicing: ChemCloser. The software can provide researchers with all core frameworks with reasonable structure and the same or similar spatial structure as the lead compound. Researchers may find frameworks with novel structures, good physical properties and stable chemical properties in these core frameworks. After splicing pharmacodynamic groups on these skeletons, it can produce the same or similar biological activity as the original active compound. [Abstract](368) [FullText HTML](101) [PDF 1563KB](3) Abstract: Taking bump-type gas foil thrust bearing as the research object, a force and deformation model of bump foil and top foil were established by elastic mechanics analysis. The foil structure deformation was calculated and the gas film thickness equation was obtained. On this basis, a fluid-solid coupling model used for calculating the lubrication performance of bump-type gas foil thrust bearings was established with use of Reynolds equation for compressible gas. The established fluid-solid coupling calculation model was verified with specific literature, proving the reliability of the algorithm. With a specific example, the dimensionless gas film pressure distribution, dimensionless gas film thickness distribution and foil structure deformation distribution of the bearing were calculated numerically. The lubrication performance of foil thrust bearing and that of rigid thrust bearing were compared. It was found that the gas film thickness of foil bearing was bigger, while the bearing capacity and friction torque of it were smaller. The influences of bump foil thickness tB, half bump length l, bump radius R0 and top foil thickness tT on the lubrication performance of the bearing were studied, and relevant curves were obtained, which showed that bearing capacity and friction torque will increase as tB or tT increase, and decrease as l or R0 increase. [Abstract](424) [FullText HTML](195) [PDF 1145KB](4) Abstract: Research based on the ultra-short baseline positioning system and Doppler velocimeter and electronic compass combination of underwater robot navigation problem, put forward a kind of based on iterative unscented Kalman filtering fusion algorithm of multi-sensor underwater integrated navigation, reduce traditional unscented Kalman filter process noise covariance matrix and measurement noise covariance matrix of the influence of the filtering precision and response time. The proposed method improves the precision of underwater multi-sensor combined navigation by iterating the results of multi-sensor data fusion several times. Firstly, the data obtained by the sensors were preprocessed. Secondly, plot the motion trajectory diagram simulated by the ultra-short baseline positioning system, the motion trajectory diagram calculated by dead reckoning and the motion trajectory diagram fused by the unscented Kalman filtering algorithm were drawn respectively. Thirdly, the unscented Kalman filtering algorithm iterates the output of multi-sensor data fusion for several times, which can achieve a better fusion effect. Finally, the feasibility and effectiveness of the combined navigation algorithm under the water are verified by multi-sensor pool test and simulation analysis. The effectiveness of the iterative unscented Kalman filtering algorithm based on underwater integrated navigation system was verified by comparing the simulated ultra-short baseline positioning data, the dead reckoning data based on the electronic compass and Doppler velocimeter and the position information of the positioning data fused with the iterative unscented Kalman filtering data. [Abstract](1042) [FullText HTML](299) [PDF 5206KB](43) Abstract:$v.abstractInfoEn
[Abstract](503) [FullText HTML](189) [PDF 789KB](0)
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A drug delivery system was designed in this paper. The system was composed of (6,5) chiral single-walled carbon nanotube ((6,5)SWCNT), doxorubicin hydrochloride (Dox), human serum albumin (HSA), and folic acid (FA). Firstly, the Dox-HSA-FA was prepared. (6,5) SWCNT was isolated by aqueous two-phase extraction. Then (6,5) SWCNT-Dox-HSA-FA was dispersed into Dox-HSA-FA by ultrasonication. Finally, cytotoxicity evaluation of the complex was performed using Hep G2 cells. The results showed that the IC50 of Dox-HSA-FA and (6,5) SWCNT-Dox-HSA-FA were 27.3 μg/mL and 25.7 μg/mL. The results indicated that the targeting effect of Dox was enhanced in the (6,5) SWCNT-Dox-HSA-FA complex.
[Abstract](448) [FullText HTML](160) [PDF 802KB](1)
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The influence of temperature, H2 pressure, hydrogen donating capabilities and catalyst on the hydroliquefaction of Hongliulin coal under mild conditions was investigated in this paper. The results show that in the range of 370~390 ℃, higher reaction temperature could promote the pyrolysis reaction of coal; in the range of 390~430 ℃, higher reaction temperature could promote the secondary cracking of heavy products. With reaction temperature increasing, the reaction pressure needs to be increased to match the reaction temperature. Moreover, compared to coal liquefaction under mild condition with recycle solvent and Fe catalyst, the effect of Fe catalyst addition on liquefaction performance with methylnaphthalene is tiny, which could be result from weak hydrogen transfer ability of methylnaphthalene. Fe catalyst has a little effect on liquefaction performance with tetralin as solvent. It could be due to that tetralin is a good hydrogen donor solvent which dissociates a large amount of activated hydrogen could stabilize most of the free radicals produced from Hongliulin coal pyrolysis, and with the addition of Fe catalyst, the activated hydrogen produced from H2 is more than needed for Hongliulin coal liquefaction process. Furthermore, the addition of alkali catalyst to Fe catalyst could promote coal conversion, oil production and H2 consumption, while reducing water production. It could be ascribed to there exists a prominent synergistic effect between alkali catalyst and Fe catalyst in Hongliulin coal hydroliquefaction, and the synergistic effect could promote the hydrolyzation of oxygen-containing moieties (such as carbonyl groups and ether bonds) and the depolymerization of macromolecular structures.
, doi: 10.14135/j.cnki.1006-3080.
[Abstract](1008) [FullText HTML](268) [PDF 710KB](4)
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A polynomial-time topological reduction plays an important role in the computation of diameter constrained reliability, because many irrelevant edges are able to be deleted and the reliability remains unchanged. However, irrelevant edges cannot be completely found from previous researches. The necessary condition of detecting irrelevant edges is a so-called open problem. In this paper, we define new metrics of path lengths, classify st-paths as real path (RP), pseudo path (PP), combination path (CP) and the shortest st-path containing a specific edge (SPE), and make it clear that the length of SPE can be approached by measuring PPs, RPs and CPs. Further, we propose an algorithm to detect innermost irrelevant edges and the complexity of the algorithm is polynomial (O(n4)). Experiment results show the effectiveness and efficiency of the algorithm.
[Abstract](518) [FullText HTML](189) [PDF 954KB](3)
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In this study, continuous and single crystal graphene films on copper (Cu) are synthesized by low pressure chemical vapor deposition (LPCVD) in the growth time of 40 minutes with the meticulously modulation of the oxygen and carbon supply in multistages synthesis processing and graphene properties dependence on the oxygen and carbon supply has been investigated. Optical microscope, field emission scanning electron microscope (FESEM) and atomic force microscope (AFM) are employed for morphology characterization while the graphene films structure are measured by transmission electron microscope (TEM), selected area electron diffraction (SAED) and Raman spectrum. It is found that double oxygen passivation (with the oxygen passivation in both nucleation and growth stages) together with the optimal methane (CH4) : hydrogen (H2) ratio will lead to the balance between nucleation and graphene growth rate to accomplish continuous single crystal bilayer graphene films in short time. The remarkable properties difference between the graphene processed by single and double oxygen passivation as well as the strong properties dependence on ratio of CH4:H2 with double oxygen passivation indicate that the nucleation and growth of graphene domains can be properly modulated by the oxygen passivation and carbon supply. Moreover, the graphene-based field effect transistor (FET) reveals the superior hole mobility of 4347 cm2 V-1s-1. Our study provides a simple LPCVD procedure to achieve high quality graphene film on Cu in short time.
[Abstract](629) [FullText HTML](236) [PDF 660KB](1)
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A defense method for linear deception attacks using KL divergence detector to detect watermarks in cyber physics system (CPS) is proposed. It is well known that linear deception attacks can degrade the performance of the remote estimator without being detected by the KL divergence detector. In order to detect such attacks, computer-based encryption methods use watermarks to encrypt and decrypt data transmitted over a wireless network to protect the system. When there is no attack, the decryption section can recover the transmitted data to ensure remote estimation performance. In the case of linear deception attacks, these data will be watermarked to expand the variance of the transmitted data, so that the data at the receiving end will no longer obey the original normal distribution. Due to the convex nature of KL divergence, the KL divergence value can be proved. It is enlarged to exceed the thresholds that have been tested by the detector so that they can help the KL divergence detector to detect the attack. The watermark encryption method has been proved to help the KL divergence detector to detect attacks or to mitigate the effects of attacks in different situations, and further discusses how to select the appropriate value of the watermark parameters, which makes the system's protection more perfect. Finally, numerical simulations are given to further illustrate the limitations of the existence of watermarks on attackers, further highlighting the practical effects of parameter selection.
[Abstract](7378) [FullText HTML](1647) [PDF 1144KB](3)
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A chain extender, styrene-maleic anhydride copolymer SMA-700, was mixed with recycled polyamide 6/carbon fiber composites (r-PA6/CF10) with a twin-screw extruder. The rheological properties, mechanical properties, morphology, crystalline structure, non-isothermal crystallization and subsequent melting behaviors of the resulting r-PA6/CF10 composites were investigated. The results show that SMA-700 has a remarkable chain extension effect on r-PA6/CF10 composites, and can significantly improve the processing performance of r-PA6/CF10. With increased mass fraction of SMA-700, the melt mass flow rate of r-PA6/CF10 decreases gradually. Meanwhile, the apparent viscosity and melt pseudo-plasticity of r-PA6/CF10 will increase with an increased mass fraction of SMA-700. Mechanical tests show that incorporation of chain extender can simultaneously improve the tensile strength and flexural strength of r-PA6/CF10 composites. A SMA-700 mass fraction of 1% and 2% maximizes the tensile strengty (125.4 MPa) and flexural strength (182.3 MPa) of the r-PA6/CF10 composites, respectively. The impact strength decreases with increased SMA-700 content. Scanning electron microscopy (SEM) used suggests that there is no phase separation between SMA-700 and PA6 matrix, implying a good compatibility between SMA-700 and PA6. Non-isothermal crystallization and subsequent melting behaviors characterized by differential scanning calorimetry (DSC) show that when the mass fraction of SMA-700 is 1%, the nucleation effect of SMA-700 may increase the crystallization rate and crystallinity of the PA6 matrix. However, with an excessive amount of SMA-700, both the crystallization rate and crystallinity of PA6 drop, and the perfection degree of α crystal form of PA6 decreases simultaneously.
[Abstract](1691) [FullText HTML](310) [PDF 1218KB](8)
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Chronic cerebral hypoperfusion (CCH) is one of the most important causes in the initiation and progression of vascular dementia. Tanshinone IIA (TSA) is an active compound isolated from the plant roots of Salvia Miltiorrhiza, which is a traditional Chinese medicine with the activities of improving blood circulation and reducing vessel stasis. In this study, the potential neuroprotective effects and mechanisms of TSA were studied using a bilateral common carotid artery occlusion (BCCAO) model in vivo and H2O2 induced oxidative damage of primary astrocytes in vitro. The results showed, first of all, TSA obviously reversed BCCAO induced cognitive impairment in rats evaluated by Morris water maze (MWM). Nissl staining showed the neuronal loss in CA1 and CA3 region were reversed by TSA. TSA also increased the expression of brain-derived neurotrophic factor (BDNF) levels in cortex and hippocampus. In H2O2-induced primary astrocytes injury, TSA suppressed the decrease of cell viability and inhibited lactate dehydrogenase (LDH) release. Secondly, TSA attenuated mitochondrial membrane potential (MMP) loss and increased ATP level. Furthermore, TSA significantly reversed the damage induced by the disorders of the mitochondria respiratory complex enzyme, and then attenuated reactive oxygen species (ROS) accumulation and lipid peroxidation, simultaneously enhanced antioxidant capacity. The results demonstrated that TSA can enhance mitochondrial bioenergetics and ameliorate oxidative stress effectively, which might contribute to the improving effect of TSA on cerebral ischemia, hypoperfusion and oxidative injuries. Our study provided new evidence to illustrate the mechanisms of protective effects of TSA on cerebral ischemia induced cognitive impairment.
[Abstract](1734) [FullText HTML](320) [PDF 750KB](2)
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Based on the design information of a cracking gas compressor in some ethylene unit, the compressor performance prediction model is established by modifying the design data. An improved BP algorithm (LR-GA-BP) is proposed for compressor performance prediction. The simulation calculation of a four-stage compressor system in the ethylene unit is carried out, and the relative errors between the calculation values and actual values of main components in cracking gas from the fourth-stage outlet of the compressor are less than 2%, and the relative errors between the calculation values and actual values of the outlet temperature and pressure of the compressor are less than 1%. It indicates the reliability of the model. The effect factors of the higher outlet temperature at the fourth-stage of the compressor were analyzed and the corresponding cooling measures were put forward, which is of good guiding significance to slow down the coking of compression system and further optimize its operation.
[Abstract](1206) [FullText HTML](495) [PDF 828KB](9)
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[Abstract](1683) [FullText HTML](539) [PDF 1169KB](3)
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Arm-type tensioner is widely used in the automotive engine belt system, whose spindle often break during actual working process caused by fatigue. For this reason, it is necessary to study the mechanics properties of the tensioner and try to find a method for calculating the spindle’s fatigue life. In this paper, the arm-type tensioner in automotive engine is taken as the research object, the mechanics analysis is carried out for the tensioner in working process, the mechanics model is established for calculating the forces acted on the tensioner’s spindle, and the method for calculating the bending stress of the tensioner’s spindle is established. On such basis, and by use of the fatigue theory and rain-flow counting method, a method is established to calculate the fatigue life of the tensioner’s spindle. With a specific example, the fatigue life of the tensioner’s spindle is calculated numerically and verified by comparing with the actual life of spindle. Several parameters’ influences on the mechanics performance and fatigue life of the tensioner’s spindle are studied. It is found that, the main factors affecting the fatigue life of the tensioner’s spindle are the distance between the pulley and the rotating arm (l1) and the bushing length (l2), and decreasing l1 and l2 can effectively increase the fatigue life of the spindle, while the length of the arm L and the vortex spring torsion stiffness T’ have no significant effects on the fatigue life of the tensioner’s spindle.
[Abstract](1527) [FullText HTML](552) [PDF 1498KB](13)
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In this paper, lean coal, fat coal and gas coal were taken as the research objects to deeply study the macroscopic gas release law and microstructural changes of coking coal during low temperature oxidation. The gas release laws were obtained by heating and isothermal oxidation and the structure of coals was characterized by N2 adsorption, scanning electron microscopy equipped with energy dispersive X-ray analysis (SEM-EDS) and infrared spectroscopy (FTIR). The results of constant temperature experiment showed that a small amount of the CO generated at a certain temperature came from the thermal decomposition of coal itself, and most of it came from the decomposition of carbon-oxygen complexes produced by oxidation reaction. N2 adsorption and SEM characterization results indicated that at 95 ℃, the destructive effect on coal structure was small, but at 190 ℃, the cracks on coal surface increased and the degree of pulverization became larger. The total volume and average pore diameter increased, but BET surface area decreased due to the blockage of some oxidation products. Al and Si elements were detected on the surface of coal, so it could be inferred that the attached particles contained Al2O3 and SiO2. FTIR characterization result showed that during the low temperature oxidation process, -OH, -CH3 and -CH2- reacted with oxygen and formed unstable carbon-oxygen complexes like C=O, -COOH and ether bonds, which were further decomposed into CO, CO2 and other gases. The thermodynamic feasibility of the proposed gas generation mechanism was verified by HSC Chemistry 6.0. Besides, the higher the volatile content of coal contained, the smaller the proportion of aromatic structure was, the more developed the pore structure was, resulting in the more easily oxidation and spontaneous combustion occurred.
[Abstract](1961) [FullText HTML](600) [PDF 1352KB](26)
Abstract:
Reasonably describing gas-liquid interaction force and bubble size distribution is the key to accurately simulate the hydrodynamic parameters of the bubble column. For the gas-liquid system, a new bubble breakup model was implemented into the population balance model (PBM) and coupled with the Euler two-fluid model. The gas-liquid two-phase flow in a bubble column with an inner diameter of 0.44 m and a height of 2.43 m was simulated. Firstly, the predicted values of bubble breakup rate and daughter bubble size distribution of the breakup model were verified. Then, the gas holdup and liquid axial velocity predicted by coupled model at different superficial gas velocities were compared with the experimental values. Moreover, the effect of lift to model (prediction result)was investigated. The results show that, both gas holdup and liquid axial velocity is improved in radial distribution when the lift force is included. The simulation value of the CFD-PBM coupled model have a good agreement with the experimental data in low and high superficial velocity. Both the turbulent dissipation rate in the reactor and the interaction between the bubbles rise with an increase in superficial gas velocity, which makes the distribution range of bubble size is widened.
[Abstract](1919) [FullText HTML](496) [PDF 818KB](9)
Abstract:
The dividing wall column has the advantage of saving energy and capital cost compared to a conventional rectifying column. At the same time, the dividing wall column has more degrees of freedom than the conventional rectifying column, and its design, control and optimization are more difficult. In this paper, the shortcomings of the simple calculation method for the four-tower equivalent model of the existing dividing wall column, an improved calculation method is proposed. The minimum operating conditions of the dividing wall column are determined according to the Underwood equation, and the operating parameters such as the number of stages, the feeding stage, side-stream stage, the reflux ratio, and the gas-liquid distribution ratio of the dividing wall column can be quickly determined in combination with the design requirements. In order to verify the effectiveness of the design method, three different ESI feed streams were selected for design and the obtained design results were strictly simulated in HYSYS. The results show that the method can be more accurate than other design methods in calculating the composition of the connecting stream between the pre-fractionator and the main column, and the total annual cost is less than other short cut design methods.
[Abstract](1739) [FullText HTML](504) [PDF 803KB](11)
Abstract:
Generally, flow shop scheduling problem assumes that all processing is performed in one factory which is called single factory production mode. Nowadays, with the advantages of low cost, low risk and high quality, distributed manufacturing has become a mainstream in the industrial production. Therefore, it is necessary to study the distributed scheduling problem. Distributed assembly permutation flow shop scheduling problem plays an important role in modern supply chains and manufacturing systems. In this paper, a modified biogeography-based optimization algorithm is proposed to solve distributed assembly permutation flow shop scheduling problem with the goal of minimizing makespan. In the initialization phase, the MBBO uses the SPT and the NR2 rule to optimize the feasible solutions. Then, in the mutation phase, the job insertion heuristic method based on the factory completion time is used to adjust the factory assignment and processing order of the jobs. Finally, the simulated annealing algorithm is combined to jump out of the local optimal solutions, which enhances the global search ability of the algorithm. Simulation experiments based on 900 small instances and 540 large instances and comparison with the existing 12 heuristic algorithms and the basic biogeography-based optimization algorithm verify the superiority of the MBBO. Besides, the new best known solutions for 70 instances are found.
[Abstract](5508) [FullText HTML](778) [PDF 617KB](6)
Abstract:
In parallel system, the arrangement graphs An,k has good properties such as symmetry, small diameter, and high fault tolerance. Subsystem reliability is defined as the probability that there is still a normal operating subsystem when the system has faults. It is usually used to measure the system health status, and the calculation of subsystem reliability is an NP-hard problem. This paper discusses the robustness of the reliability of the subgraphs and the approximate algorithm of reliability. Further, the Monte Carlo algorithm for arrangement graphs is constructed. The simulation results show that the constructed Monte Carlo algorithm is much better than the known approximation algorithm. In particular, the error of Monte Carlo approximation of A3,2 subgraph reliability is less than 1%.
[Abstract](7660) [FullText HTML](2912) [PDF 892KB](5)
Abstract:
In this study, the salt-tolerant bacteria were used to degrade the organic matter and ammonia nitrogen in the shale field produced water. The degradation performance and membrane fouling characteristics of the anoxic reactor-membrane bioreactor (AR-MBR) and the separate MBR reactor were investigated. The difference between two reactors was that the AR-MBR system was provided with a filament filler to form an anoxic circumstance in front of the MBR reactor. The results showed that the degradation of the AR-MBR combined reaction system was better than that of the MBR reactor alone. The removal rates of TOC were 88% in AR-MBR and 80% in MBR, the removal rates of ammonia nitrogen were 90% and 75%, respectively.The transmembrane pressure(TMP) and the total membrane fouling rate of the AR-MBR was slower than that of the MBR reactor. The main reason was that the particle size of the floc in the AR-MBR reactor was larger than that in the MBR reactor, which was not easy to block the membrane pores. On the other hand, the soluble microbial products(SMP) and extracellular polymeric substances (EPS) content was lower in AR-MBR reactor than that of the MBR reactor, while the protein to polysaccharide concentration ratio (PN/PS) was higher, the reduction of fouling substance on membrane alleviated the membrane fouling phenomenon.
[Abstract](7425) [FullText HTML](2071) [PDF 1041KB](6)
Abstract:
In this study, a bacterial strain named 206BP, with efficient degradation for the organic matters in shale gas produced water, was isolated from high-salt wastewater and surrounding soil samples. Morphological observation, gram stain and 16SrDNA gene sequence analysis were used to identify the strain 206BP and the results showed that it belonged to the Bacillus genus as it had 99% similarity with Bacillus purgationiresistens and other orthologs. The diameters of the strain and spore were about 2.0 μm and 0.3-0.6 μm, respectively. Besides, it was confirmed the strain was Gram-positive, capable of producing urease for urealysisand hydrogen sulfide gas as well as hydrolyzing starch and reducing nitrate and nitrite. The growth of the strain 206BP was observed that it stayed at the lag phase in the first 5 h and enter the exponential growth phase in the period of 5-22 h, finally reaching the stationary phase after 24 h. Meanwhile, the effects of NaCl concentration, carbon source, nitrogen source and pH on growth characteristics were also investigated. The experimental results reflected the strain 206BP could grow well and was moderately salt-tolerant with 0-8w% NaCl. In addition, its optimum growth pH was in the range of 5-8 and the optimum carbon and nitrogen sources were glucose and urea, respetively. The bacterial concentration in the stationary phase of the growth curve could increase with more glucose while the stagnation period of the growth curve was prolonged as the glucose concentration exceeded 5000 mg·L−1. The added urea had a positive correlation with the strain 206BP growth but the promotion faded away with the urea concentration up to 50 mg·L−1.
[Abstract](952) [FullText HTML](249) [PDF 1116KB](11)
Abstract:
Cobalt selenide is considered to be an ideal anode material for lithium-ion batteries because of its good lithium-ion insertion/extraction capability. However, due to large volumetric expansion upon cycling and insulating nature, the performance of cobalt selenide is limited. In this study, we obtained CoSe2-C/C-PAN by coating CoSe2-C polyhedrons with polyacrylonitrile (PAN) in N2 atmosphere. The CoSe2-C polyhedrons were successfully synthesized using Co-based zeolitic imidazolate framework (ZIF-67) as precursor through a two-step method, including carbonization of ZIF-67 and subsequent selenization. The resultant CoSe2-C/C-PAN presents high specific capacity and excellent cycling stability with an initial discharge capacity of 1 440 mAh/g at 0.2 A/g and a reversible capacity of 653 mAh/g at 1 A/g after 200 cycles as anode material of Li-ion battery. The excellent battery performance of CoSe2-C/C-PAN should be attributed to the synergistic effect of nanostructured CoSe2 and carbon materials, in which the nanostructured CoSe2 possesses high reactivity towards lithium-ions and the carbon can provide a continuous conductive matrix to facilitate the charge transfer and an effective buffering to mitigate the structure variation of CoSe2 during cycling. And such significantly enhanced electrochemical performance should be ascribed to the improved electrical conductivity and structure stability of C-PAN.

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2020, 46(4): 445-453.   doi: 10.14135/j.cnki.1006-3080.20190428005
[Abstract](8402) [FullText HTML](2211) [PDF 1359KB](20)
Abstract:
2020, 46(4): 454-463.   doi: 10.14135/j.cnki.1006-3080.20190324001
[Abstract](207) [FullText HTML](158) [PDF 1336KB](2)
Abstract:
During the reaction crystallization of picromerite for potassium sulphate, a large amount of potassium-containing mother liquor is produced. In order to improve the utilization of potassium resources, different crystallization strategies performed under different vacuum degrees were used to investigate the recovery and utilization of potassium resources in reaction mother liquor at 108, 75, 35 ℃. The purity, morphology and particle size distribution of the three routes of evaporation crystallization were systematically studied using XRD, chemical analysis, particle size distribution and other analytical methods. The ending point of evaporation water for potassium resource recovery under metastable conditions was determined. The experimental results show that the products of the evaporation crystallization process at 108 ℃ are langbenite and potassium chloride, and the crystal products at 75 ℃ and 35 ℃ are potassium chloride. At 35 ℃, the potassium content and potassium recovery rate of the products reach the highest within the same time, which are 44.64% and 78.73%, respectively. Meanwhile, combined with the characteristics of drought and little rain in the western salt lake area, it is determined that the evaporation crystallization at room temperature is the best process for potassium resource recovery in the mother liquor of reaction of picromerite. The experimental results provide relevant basis and reference for the further improvement of utilization of potassium resource in the resource-type potassium sulfate production process.
2020, 46(4): 464-471.   doi: 10.14135/j.cnki.1006-3080.20190329006
[Abstract](10161) [FullText HTML](2796) [PDF 1009KB](10)
Abstract:
TPA-functionalized prepolymer (iPrTPA-PrePBO, tBuTPA-PrePBO) was synthesized by treating 4,4'-dicarbonylchloride-4''-isopropyltriphenylamine (iPrTPADC) and 4,4'-dicarbonyl chloride-4''-tertbutyltriphenylamine (tBuTPADC) with 4,6-di(tertbutyldimethylsilylamino)-1,3-di(tertbutyldimethylsiloxy)benzene (TBS-DAR), respectively. Then, a thermal cyclization reaction was carried out to obtain two benzoxazole polymers containing electron-donating triphenylamine groups (iPrTPA-PBO, tBuTPA-PBO). The prepolymers and benzoxazole polymers were characterized by nuclear magnetic resonance spectroscopy(1H-NMR) and Fourier transforminfrared spectroscopy (FT-IR). Thermogravimetry (TG), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and fluorescence spectroscopy were used to analyze the solubility, thermal and photophysical properties of the polymers. The results showed that the two prepolymers had excellent solubility in conventional solvents, and the polymers after thermal cyclization reaction also had moderate solubility in solvents with a high boiling point such as dimethyl sulphoxide. The polymers existed in nitrogen atmosphere and air showed excellent thermal stability with a temperature above 500 ℃. Photophysical studies showed that polymers had higher fluorescence quantum yields than the conventional PBO, and their band gaps (about 2.0 eV) were close to the semiconductor.
2020, 46(4): 472-479.   doi: 10.14135/j.cnki.1006-3080.20190315001
[Abstract](1310) [FullText HTML](296) [PDF 1148KB](2)
Abstract:
The lignin-based film was obtained by addition polymerization of lignin and polycaprolactone (PCL) by using hexamethylene diisocyanate (HDI) as the linking agent and stannous isooctylate as the catalyst. The structure and properties of the materials were characterized by infrared spectroscopy (FT-IR), NMR, XRD, thermogravimetry (TG), mechanical properties, contact angle, UV test and scanning electron microscopy (SEM). The effects of lignin content, isocyanate fraction and molecular weight of PCL on the properties of the films were also investigated. The results showed that the biodegradable soft polycaprolactone was successfully introduced into the lignin. The initial degradation temperature reached at 338.10 ℃ with the mass fraction of lignin of 36.36%, indicating that the modification enhanced the thermal stability of lignin. The obtained film was flexible without breaking and exhibited prominent mechanical strength. The elongation at break and tensile strength of the film could reach at 1 114.84% and 17.66 MPa at the mass fraction of lignin of 9.09%, respectively .With the increase of mass fraction of lignin, the mechanical properties of the film were decreased, but when the mass fraction of lignin was 27.27%, the elongation at break, tensile strength and elastic modulus of the film could still reach about 235.09%, 24.70 MPa and 262.49 MPa, respectively. Furthermore, the hydrophilic properties of the film was tunable with respect to the composition which could be adjusted as on-demand during practical applications. Exceptionally, UV absorption test manifested that the films had extraordinary UV-shielding property and could block against 100% UV light in the UV region (290—400 nm). Thus, these lignin-based films have great prospect for diverse promising applications, such as agricultural fields, packaging areas and UV-shielding biomaterial fields.
2020, 46(4): 480-487.   doi: 10.14135/j.cnki.1006-3080.20190404002
[Abstract](748) [FullText HTML](292) [PDF 1531KB](6)
Abstract:
By controlling the molar ratio of D-enantiomer to L-enantiomer of the lactide, a series of di-stereoblock polylactides (di-sb-PLA) bearing similar block sequences between poly(D-lactide) (PDLA) and poly(L-lactide) (PLLA) were synthesized by ring-opening polymerization of L-lactide (L-LA) using hydroxyl terminated PDLA (HO-PDLA) as a macromolecular initiator. Micro/nanofibers were then fabricated by electrospinning di-sb-PLAs from their dichloromethane (DCM) and hexafluoroisopropanol (HFIP) mixtures. The thermal and mechanical properties, fiber morphology and crystallization properties of di-sb-PLAs were analyzed. The results of DSC showed that di-sb-PLA formed complete stereocomplex(sc) crystals with the melting point higher than 215 ℃, and no homocrystal was formed. The crystallization ability of sc was decreased with an increase in length of each block. It is worth to note that sc of stereoblock PLA was formed on molecular-scale without post-processing compared with PLA homopolymers, which enhanced the heat resistance and improved the elongation at break of solution-cast film to 250% without losing tensile strength, especially for di-sb-PLAs that has higher molecular weight. After electrospinning, the as-spun micro/nanofibers of di-sb-PLA were homogeneous and smooth, in which PLA molecules were almost amorphous. A large amount of sc crystals were then formed by cold crystallization during heating-up process, and the melting points of sc crystals in these fibers were increased by 8 ℃ as compared with the melt-quenched samples. Moreover, the results of in-situ ATR-FT-IR at variable temperature disclosed that the formation of sc crystals was related to the interactions between side methyl groups and carbonyl groups in PLA. The results hold promise for the further application of di-sb-PLA.
2020, 46(4): 488-494.   doi: 10.14135/j.cnki.1006-3080.20190409003
[Abstract](8252) [FullText HTML](2944) [PDF 948KB](38)
Abstract:
Inspired by the adhesion between mussels and rocks, a series of hydrogels composed of poly[3-(methacrylamido)propyl] trimethylammonium chloride polyacrylamide dopamine (PMPTCDMA) and poly vinyl benzenesulfonic acid sodium salt hydrate (PNaSS) based on charge interaction were prepared. Without introducing covalent bond or coordination bond, opposite charge interaction was adopted in the PNaSS/PMPTCDMA hydrogels system. The cationic polyelectrolyte, PMPTCDMA, being simulated the proteins secreted by mussels, similarly contains abundant positive charges and catechol residues. The anionic polyelectrolyte, PNaSS, imitates the rocks with negative charged surfaces. The mechanical performance of the obtained PNaSS/PMPTCDMA hydrogels could be tuned with the content of catechol and water. The PNaSS/PMPTCDMA hydrogels exhibit high stretch performance and robust adhesion property. After being soaked with saline, the hydrogels reached high tensile fracture stress of 1.89 MPa. Besides, the shear strength of adhesion on glass slides increased to 6.17 MPa, which is almost three times stronger than the origin value (1.58 MPa), revealing a comparable performance to commerical adhesives. The mussel-inspired polyelectrolyte hydrogels were promising for the adhesion of devices underwater, or in humid environments.
2020, 46(4): 495-501.   doi: 10.14135/j.cnki.1006-3080.20190329002
[Abstract](8041) [FullText HTML](1985) [PDF 863KB](12)
Abstract:
Volatile organic compounds (VOCs), which include benzene, toluene and xylene, are harmful to both human health and the environment. It is important to control and reduce the release of VOCs. Transition-metal oxides have been widely studied due to their low cost and relative high activity for catalyzing VOCs. In this work, manganese oxide was used to coat zeolite molecular sieve, producing the composite by a one-step redox reaction between potassium permanganate and manganese nitrate. By introducing a template agent, the reaction temperature and concentration are optimized to modulate the structure and properties of manganese oxide, producing a layered porous structure that sets free the pore of the zeolite molecular sieve thoroughly. The large special surface area of zeolite molecular sieve facilitates the adsorption of VOCs and the manganese oxide coating promotes the catalytic oxidation of VOCs. The results show that the use of different reaction temperature and catalyst concentration leads to the changes of the morphology of manganese oxide, the specific surface area of the composite, the mole ratio of lattice oxygen to adsorbed oxygen, and the mole ratio of Mn3+ to Mn4+ in manganese oxide catalyst. The special surface area of the composite, coating amount, the mole ratio of lattice oxygen to adsorbed oxygen and Mn3+ to Mn4+ together impact the catalytic performance of the composite. An appropriate amount of manganese oxide coated molecular sieve catalyst prepared under ice bath shows the best catalytic performance for toluene (0.26 g/m3), which the toluene conversion reaches above 90% at 256 °C.
2020, 46(4): 502-509.   doi: 10.14135/j.cnki.1006-3080.20190329001
[Abstract](652) [FullText HTML](271) [PDF 1026KB](7)
Abstract:
Over the past few decades, lithium-ion batteries (LIBs) have attracted extensive interests in energy storage devices due to their high energy density, long cycle life and environmental friendliness. However, the low specific capacity of conventional anode materials restricts the commercial applications of LIBs. Therefore, it is crucial to develop advanced electrodes for next-generation LIBs to meet the increasing energy requirements. Metal-organic frameworks (MOFs) are potential candidates for anode materials due to their high surface area, controlled pore size and structural diversity, but their poor conductivity and easy aggregation often result in the decline of electrochemical performances of LIBs. To further improve the overall performances of MOF as anode materials for lithium ion batteries, an approach involved electrostatic attraction and chemical liquid deposition was developed to fabricate CoNi-MOF/RGO composite nanoflakes using reduced graphene oxide (RGO) as substrate, cobalt chloride and nickel chloride as precursors, and benzenedicarboxylic acid as organic ligands. The addition of RGO not only induced the structural transformation of CoNi-MOF from cross-linked lamellae to two-dimensional nanoflakes, but also enhanced the conductivity of CoNi-MOF/RGO composite. Subsequently, the coin type lithium ion battery was assembled by using CoNi-MOF/RGO as anode materials. The electrochemical tests indicated that the obtained CoNi-MOF/RGO electrode possessed a high charge specific capacity of 747 mA·h/g at a current density of 0.2 A/g after 100 cycles. Even at a high current density of 5.0 A/g, a high capacity of 289 mA·h/g was still achieved, which is much higher than that of CoNi-MOF, demonstrating its excellent electrochemical performances.
2020, 46(4): 510-516.   doi: 10.14135/j.cnki.1006-3080.20190417001
[Abstract](1025) [FullText HTML](272) [PDF 1228KB](5)
Abstract:
Cucurbit[n]urils (CB[n]s) are macrocyclic host molecules with polar carbonyl groups on both portals, which enable CB[n]s to bind strongly and selectively with cationic species, especially to protonated organic amines. Here, a supramolecular polymer has been successfully constructed by the self-assembly between a cucurbit[5]uril analogue (decamethyl substituted methylene bridge cucurbit[5]uril, Me10TD[5]) and 1,3,6,8-tetrakis(4-aminophenyl) pyrene tetrahydrochloride salt in aqueous solution through portal interactions. Diverse measurements were used to characterize the formation of this polymer, including fluorescence emission spectrum, 1H-NMR spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The 1H-NMR measurements and the Job's plot indicated that 1,3,6,8-tetrakis(4-aminophenyl) pyrene tetrahydrochloride salt and Me10TD[5] were combined in a mole ratio of 1∶2. The association constant (Ka) was calculated to be (7.1 ± 0.7) × 104 L/mol by non-linear curve-fitting method based on the fluorescence experiments. Transmission electron microscopy image and the dynamic light scattering measurements demonstrated that 1,3,6,8-tetrakis(4-aminophenyl) pyrene tetrahydrochloride salt and Me10TD[5] could self-assemble into supramolecular polymers and the self-assembly behavior would lead to a certain degree of red shift of the maximum emission wavelength along with the decrease in fluorescence intensity. Meanwhile, the recognition performance of the polymer on metal ions was studied. Upon the addition of Ba2+, Ca2+, Co2+, Ni2+, Pd2+, Zn2+, Fe2+, Mg2+, Cd2+, Mn2+, Cu2+, it was found that Ba2+ could significantly enhance the fluorescence of the system and had a certain degree of anti-interference. Therefore, this polymer can be used to detect Ba2+, and the detection limit of the polymer for Ba2+ is 7.6 × 10-6 mol/L.
2020, 46(4): 517-525.   doi: 10.14135/j.cnki.1006-3080.20190427001
[Abstract](457) [FullText HTML](243) [PDF 1158KB](3)
Abstract:
Influences of vacuum freeze-drying on the active constituent of Panax notogiseng ( P. notoginseng) and the optimal drying process with the content of Panax notoginseng Saponins (PNS) and Dencichine were investigated. The single factor experiment was utilized combining with response surface methodology and satisfaction function to optimize the drying process of P. notoginseng. On the basis of single factor experiments, different optimum conditions including clapboard temperature and vacuum pressure were selected, and the method of response surface analysis was adopted according to the central composite design (CCD) experimental design principles. In addition, the P. notoginseng quality was evaluated by scanning electron microscope (SEM). The optimum drying conditions of the P. notoginseng are as follows: vacuum pressure of 56.9 Pa, the clapboard temperature of 45.2 ℃. Under the optimal drying conditions, the mass content of PNS and Dencichine could reach 9.77% and 1.76%, respectively. The satisfaction function results showed that the maximum value of the optimum process conditions was 4.353, and the values of three parallel experiments are similar to the optimum model. This technology could be used to guide industrial production of P. notoginseng and provide a theoretic basis.
2020, 46(4): 526-532.   doi: 10.14135/j.cnki.1006-3080.20190422001
[Abstract](8314) [FullText HTML](2259) [PDF 1089KB](20)
Abstract:
Proteins are widely used as reagents in laboratories and as therapeutics for a variety of diseases. However, the native proteins are prone to aggregation and can be denatured under extreme conditions such as freezing, drying and dehydration, leading to a reduced activity, and thus an increased dosage. To achieve protein protection under extreme conditions, we prepared two types of amino acid polymers, poly-(L-lysine) (PLL) and poly-L-glutamate (PLG) from the rapid ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydride (NCA) using lithium hexamethyldisilazide (LiHMDS) as the initiator. β-galactosidase (β-Gal) was used as a model protein to examine the protein protective effect of the synthesized amino acid polymers during lyophilization. The results showed that the presence of PLL and PLG blending had significant protection effect on β-Gal activity during lyophilization. The enzyrnatic activity of the lyophilized protein was improved from 38%（without protecting agent）to 77%（with protecting agent）. The results suggest that amino acid polymers are good candidates for protein stabilization under extreme conditions. The easy operation of LiHMDS-initiated, moisture insensitive and rapid NCA polymerization implies great potential of this strategy to prepare simple amino acid polymers for screening of protein stabilization agents.
2020, 46(4): 533-542.   doi: 10.14135/j.cnki.1006-3080.20190428002
[Abstract](9463) [FullText HTML](2441) [PDF 1223KB](42)
Abstract: