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摘要:A Lactobacillus buchneri GBS3 strain isolated from the traditional Chinese pickles was used for the production of 3-phenyllactic acid(PLA), an important compound with antimicrobial activities against a wide species of grampositive and gram-negative bacteria and some fungi. The growth performance of this strain in the de Man, Rogosa and Sharpe(MRS) medium, the production of metabolites of valuable organic acids, and the biosynthesis of PLA using this strain as the whole-cell biocatalyst and phenylpyruvic acid(PPA) as the precursor, were investigated experimentally. The uniform design method with overlay sampling was developed for the optimization of the biotransformation conditions. The results showed that although it produced naturally lactic acid with the maximum concentration of 1.84 g·L^(-1) and PLA with the concentration of 0.015 g·L^(-1) after 66 to 72 h cultivation in MRS broth by fermentation, the present strain displayed an effective utilization ability by transforming PPA to PLA. By the uniform design method with overlay sampling for the design and optimization of transformation conditions, a maximum yield of 10.93 g·L^(-1) PLA with the mole conversion ratio of 83.07% from PPA to PLA was achieved under the optimized condition, i.e., 20 g·L^(-1) glucose, 270 g·L^(-1) cells, 13 g·L^(-1) PPA, pH 8.0 and the reaction time of 15 h, indicating that Lactobacillus buchneri GBS3 was an interesting strain for the biosynthesis of PLA via the microbial transformation. The prediction of PLA yield under different conditions was achieved successfully based on the limited information of only a small number of experiments by the uniform design with overlay sampling. Therefore, the present methodology is effective and helpful for the optimization of the biosynthesis processes of PLA.
摘要:In this work,a techno-economic study for the solvent based extraction of methacrylic acid from an aqueous solution is *** involved phase equilibrium calculations in process design are verified by measured experimental ***,experiments are conducted with different solvent candidates to measure LLE(liquid–liquid equilibrium)data and to establish the effects of extraction temperature and dosage of ***,the binary interaction parameters for the UNIQUAC model to be used for equilibrium calculations are fine-tuned with measured ***,a process for the solvent based extraction of methacrylic acid recovery is designed and verified through simulation with the regressed UNIQUAC model *** optimal configuration of the process flowsheet is determined by minimizing the total annualized *** the three solvent candidates considered-cyclohexane,hexane and toluene-the highest efficiency and the lowest total annualized cost is found with toluene as the solvent.
摘要:By choosing neuroimmunophilin FKBP12 as a therapeutical target, we have attempted to discover a new structural drug for treating neurodegenerative disease. This drug should possess neurotrophic activity and not affect the immune system. Based on the crystal structure of FKBP12, FK506 and Calcineurin complex, a series of small organic molecules were designed. These molecules were to have the ability of binding to FKBP12 in a virtual screening. By using a solution parallel synthetic method, these compounds were synthesized. The neuroprotective and neuroregenerative activities of these compounds were evaluated by binding assays, PC12 cells survival and neurite outgrowth model, chick dorsal root ganglion cultures (DRG) and 6-OHDA lesioned mice sympathetic nerve endings model. The evaluation results of these compounds showed that compound N308 has great promise as a candidate for a neuroprotective and neuroregenerative agent.
摘要:The direct hydrogenation of CO2 using H2 gas is a one-stone-two-birds route to produce highly valueadded hydrocarbon compounds and to lower the CO2 level in the ***,the transformation of CO2 and H2 into hydrocarbons has always been a great challenge while ensuring both the activity and selectivity over abundant-element-based *** this work,we designed a Schottky heterojunction composed of electron-rich MoC nanoparticles embedded inside an optimized nitrogen-doped carbon support(MoC@NC)as the first example of noble-metal-free heterogeneous catalysts to boost the activity of and specific selectivity for CO2 hydrogenation to formic acid(FA)in liquid phase under mild conditions(2 MPa pressure and 70℃).The MoC@NC catalyst with a high turnover frequency(TOF)of 8.20 molFA molMoC^-1 h^-1 at 140℃ and an excellent reusability are more favorable for real applications.
摘要:Plackett-Burman design and response surface methodology were applied in order to optimize the fermentation medium of (R)-α-hydroxyphenylacetic acid ((R)-HPA) producing Bacillus sp. HZG-19. The factors playing important roles in the production of (R)-HPA were selected based on Plackett-Burman design. The path of steepest ascent was undertaken to optimize said fermentation medium. Finally, the optimal levels of the factors with the greatest change in regard to product yield were further optimized using Box-Behnken and response surface analysis. The optimal conditions were found to be as follows: casein peptone 30.49 (g × L-1), glycerol 14.09 (g × L-1), KH2PO4 0.1345 (g × L-1), K2HPO4 0.01 (g × L-1), CaCl2 0.1 (g × L-1), MnSO4 0.01 (g × L-1). Under the optimal conditions described above, the yield of (R)-HPA reached 63.30%, which indicated an increase of 14.9%, as compared to the yield obtained before optimization.
摘要:A widely used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was imprinted on poly (4-vinylpyridine) (4-VP) using (40%) ethyleneglycol dimethacrylate (EGDMA) as crosslinking agent. The classical imprinting technology makes use of a high degree of crosslinking which does not allow the template molecules to move freely. So the binding sites, located in the central area of the three dimensional polymer matrix are hard to be accessed and the template molecules cannot be extracted totally. But here we propose a low crosslinked system with high specificity and selectivity. The imprinted and non-imprinted polymers were characterized by various spectroscopic techniques. The extent of binding was followed by batch equilibration method and compared with the respective non-imprinted polymer. Conditions for maximum specific rebinding were set by altering certain factors like template/monomer ratio, concentration of template solution, rebinding medium, mass of polymer and time of incubation. The selectivity of the imprinted polymer was investigated by comparing the binding with structural analogues of 2,4-D like, phenoxyacetic acid (POA), 4-chlorophenoxyacetic acid (4-CPOA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The imprinted polymer exhibited high affinity towards the template molecule and was selectively rebound to the specific sites. The binding towards the structural analogues depends on the number of chlorine in the benzene ring.
摘要:设计研制了一种光催化超滤膜反应器,并选用一种颗粒状纳米级TiO2作光催化剂,对染料acidBlue7光氧化降解进行了研究。影响染料降解的因素包括:错流速度、催化剂浓度、染料初始浓度、溶液的pH值以及曝气条件。研究结果发现,光催化超滤反应器对染料废水处理具有较高的处理效果,且颗粒状光催化剂能够实现良好分离。
摘要:A factorial experimental design method was used to examine the “Cu2+” removal from acid mine drainage wastewater by ion exchange technique. Ion Exchange technique is preferred because of reduced sludge generation compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (3, 5, and 6), flow rate (5, 10, 15 L/hr), resin bed height (20, 40 and 60 cm) and initial concentration of the metal (100, 150 and 200 mgl-1) at three levels. The efficiency of metal removal was determined after 100 min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was recommended and it was found to fit the experimental data very well. The results were analyzed statistically using the Student’s t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage “Cu2+” removal. In this study , pH was thus found to be the most important variable.
摘要:Functional manipulation of biosynthetic enzymes such as cytochrome P450 s(or P450 s) has attracted great interest in metabolic engineering of plant natural *** and mogrosides are plant triterpenoids that share the same backbone but display contrasting *** structural and functional diversity of the two metabolites can be manipulated by engineering P450 ***,the functional redesign of P450 s through directed evolution(DE) or structure-guided protein engineering is time consuming and challenging,often because of a lack of high-throughput screening methods and crystal structures of P450 *** this study,we used an integrated approach combining computational protein design,evolutionary information,and experimental data-driven optimization to alter the substrate specificity of a multifunctional P450(CYP87 D20)from *** three rounds of iterative design and evaluation of 96 protein variants,CYP87 D20,which is involved in the cucurbitacin C biosynthetic pathway,was successfully transformed into a P450 mono-oxygenase that performs a single specific hydroxylation at C11 of *** integrated P450-engineering approach can be further applied to create a de novo pathway to produce mogrol,the precursor of the natural sweetener mogroside,or to alter the structural diversity of plant triterpenoids by functionally manipulating other P450 s.
摘要:An effective cancer nanodrug not only needs to load a large fraction of pharmaceutical molecules and release them in responsive ways, to function as imaging and photothermal agents, but also needs to possess the favorable morphologies that are favored by the EPR effect of cancer tissues. In this study, we designed a spherical nanodrug by forming clusters using DOX and a polymer-engineered rGO. These spherical nanodrugs had a diameter of around 750 nm and assumed both functionalities of chemical therapy and the photothermal effect. In addition, this nanodrug featured a high-loading capability of DOX, a pH-responsive release profile, a self-fluorescent capability, and an effective accumulation in cancer cells. The layer-by-layer assembly of three cycles of polyethylene glycol (PEG) and polyacrylic acid (PAA) around the rGO core was indispensable in achieving a chemically-modified rGO precursor that assembled with DOX to produce the spherical nanodrug. The spherical nanodrug effectively decreased cell viability upon NIR irradiations.
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