Journal of The Chinese Institute of Chemical Engineers最新文献

Factors affecting the morphology of Streptomyces avermitilis and avermectin production in submerged cultivation, including nitrogen sources, inoculum level and DO (dissolved oxygen) tension in the broth were investigated in a 50-L bioreactor. It was found that a combination of soybean meal and yeast meal as nitrogen sources and 4.3% inoculum led to pellet formation, and the pellet morphology facilitated to maintain DO > 20% in the early stage of fermentation. With the aid of image analysis tools, area and density of pellets in different batches were calculated. Results show that higher dissolved oxygen tension was favorable for pellet formation and avermectin production.

The overexpression of human c-Met tyrosine kinase induces the tumor proliferation and migration. Commercial drug is still not available for inhibiting this target. The structure of human c-Met was simulated and validated by molecular modeling. Compounds from our laboratory database, including natural products and anticancer agents, were employed for the docking analysis. De Novo drug design was further performed for three compounds with highest DockScore value to discover the novel inhibitors. Through the adsorption, distribution, metabolism, excretion and toxicity (ADMET) descriptor, only compounds A₂, B₃, C₂ and C₅ were selected. Through the pharmacophore analysis, ARG1086, HIS1088, ARG1208, ASN1209, ALA1226, ARG1227, ASP1228, TYR1230, and GLU1233 were suggested as the key residues because of strong pharmacophore features. In addition, the pharmacophore features of candidates consisted with the active site properties. The added fragments produced the strong interaction with the surrounding residues and yielded hydrogen bonds (HBs). Thus, the interaction energy between the ligand and the receptor was enhanced. Besides, the values of several scoring functions (PLP1, PLP2, and DockScore) of candidates were comparatively higher than compounds A, B, C, and Kirin. According to the aforementioned analyses, compounds A, A₂, B, B₃, C, C₂ and C₅ were suggested as the potent c-Met inhibitors. Besides, the scaffolds of compounds A, B, and C provided the direction for further drug design.

The S-alkylation (substitution on sulfur atom) of 2-mercaptobenzimidazole (MBI or ArSH) by allyl bromide (RBr) was successfully carried out in an aqueous solution of KOH/organic solvent two-phase medium. The reaction, which may take place either in the organic phase or on the interface, is greatly enhanced in the presence of KOH without the aid of quaternary salts as the catalyst to promote the reaction. No product was obtained from N-alkylation (substitution on nitrogen atom) during or after the reaction period by using a limited amount of allyl bromide (RBr) relative to that of MBI. Based on the experimental evidence, the kinetic behaviors and the characteristics of the reaction are sufficiently described by the pseudo-first-order rate law. The effects of the reaction conditions, including the agitation speed, the amount of KOH, volume of water, volume of dichloromethane, amount of allyl bromide, amount of 2-mercaptobenzimidazole, organic solvents and temperature on the conversion of allyl bromide and the apparent rate constants (k_app) were investigated in detail. Peculiar result is obtained in studying the effect of the volume of water on the conversion (or the reaction rate) in this work. Rational explanations are provided for the observed phenomena from experimental results.

The analysis of solvent extraction in the membrane modules of cocurrent, countercurrent and cross-flows with external recycle, has been carried out by mass-transfer theory, analogous to heat transfer in recycled heat exchangers. Considerable improvement is achievable by recycle operation if the increase in mass-transfer coefficient by applying the recycle effect can compensate for the decrease in the driving force of mass transfer due to the dilution of inlet feed solution. Under comparable conditions most solute is extracted in countercurrent-flow arrangement, the least in cocurrent-flow. However, the separation efficiencies of the three flow-type devices approach in unity for lower feed concentration and/or larger flow rate and/or larger reflux ratio.

The effect of internal reflux in the raffinate phase for membrane extraction through a cross-flow rectangular module was investigated. Theoretical analysis of mass transfer in cross-flow devices with or without recycle was analogous to heat transfer in cross-flow heat exchangers. In contrast to a device without reflux, considerable improvement in mass transfer is achievable if cross-flow membrane extractors are operated with reflux which provides the increase of fluid velocity, resulting in reduction of mass-transfer resistance. It is concluded that reflux can enhance mass transfer, especially for large flow rate and feed-concentration solution operated under high reflux ratio.

Response surface methodology (RSM) was employed to optimize the cultivation conditions of Bacillus subtilis S3 for the enhancement of iturin A, a lipopeptide antibiotic used as biological pesticide, production in solid-state fermentation (SSF). The statistic experimental model predicted a maximum iturin production of 11.435 mg/g-wet solid material. Verification of the calculated maximum was done with experiments that were performed in the culture media representing the optimum combination found, and the iturin A production of 11.447 mg/g-wet solid material (average of three repeats) was obtained when B. subtilis S3 was cultivated at 25 °C for 5 days in solid fermentation containing high gluten flour 10 g and rice bran 50 g in addition to glucose 1.15%, KH₂PO₄ 1.27 mM, MgSO₄ 5.08 mM, peanut oil 1.01%, inoculum 19.49% and water content 44.97%. The iturin A production by B. subtilis S3 was increased significantly by 23%, from 9.26 mg/g-wet solid material to 11.447 mg/g-wet solid material when the strain was cultivated in the optimal medium developed by surface response methodology, as compared to medium conventionally developed by one-factor-at-a-time. The yield of iturin A (11.447 mg/g-wet solid material, with 45% moisture content) produced by B. subtilis S3 reported in this study is the highest reported to date for B. subtilis species in SSF. In addition, the use of rice bran as a substrate in solid-state fermentation for iturin A production by B. subtilis is unique.

The extraction of ferulic acid, a pharmacologically active ingredient from the root of Ligusticum chuanxiong, with ultrasonic extraction was investigated. Percolation and supercritical fluid extraction (SFE) were employed to make comparisons with ultrasonic extraction. Three variables, which included the concentration of solvent, the ratio of solvent volume/sample (mL/g), and extraction time, were found to have a great influence on ultrasonic extraction. The optimum extraction was with pure ethanol with a solvent volume/sample ratio 8:1 (mL/g) and extraction time of 30 min. Under the optimum extraction conditions, the extraction yield could reach 8.8% which was higher than that using SFE with ethanol as co-solvent and a content of ferulic acid of 0.7%; both the yield and the content were higher than those obtained by percolation. Ultrasonic extraction significantly shortened the time required for the extraction process. Overall, ultrasonic extraction was shown to be highly efficient in the extraction of ferulic acid from Ligusticum chuanxiong.

Liquid–solid chromatography (LSC) is the oldest of the various liquid chromatography methods. Despite the fact that high-performance liquid chromatography (HPLC) operation leads to better separation and analysis, classical column chromatography and thin-layer chromatography (TLC) are still widely practiced because of their convenience. In this study, a modified silica gel column chromatography was designed with the objective of reducing the amount of solvent required to achieve the same degree of separation as the classical silica gel column chromatography. The separation of squalene and fatty acid steryl esters (FASEs) from non-polar lipid fraction (NPLF) of soybean oil deodorizer distillate (SODD) was employed as a model system to test the effectiveness of this new design. Modified silica gel column chromatography process is feasible from economic point of view compare to classical silica gel column chromatography because it significantly reduces the amount of solvent and time required to achieve the same degree of separation. By employing modified silica gel column chromatography to obtain the squalene-rich fraction, the mobile phase volume and elution time required as fractions of those needed in classical silica gel column chromatography are 1/73 and 1/18, respectively. To obtain the FASEs-rich fraction, the corresponding mobile phase volume and elution time are 1/221 and 1/23, respectively of those needed in classical silica gel column chromatography.

Ternary diffusion coefficients of monoethanolamine (MEA) and N-methyldiethanolamine (MDEA) in aqueous solutions have been measured at 303.2, 313.2, and 323.2 K. The systems studied are aqueous solutions containing total amine concentrations of 2.5 and 4.0 kmol/m³ and each solution prepared with four different amine molar ratios. The main diffusion coefficients (D₁₁ and D₂₂) and cross-diffusion coefficients (D₁₂ and D₂₁) and the density and viscosity of the aqueous amine solutions are discussed and analyzed as a function of temperature and their concentration.

A consortium-GB containing two microorganisms Galactomyces geotrichum MTCC 1360 and Bacillus sp. VUS was able to degrade sulfur-containing dye Brilliant Blue G, optimally at pH 9 and temperature at 50 °C. The ability of consortium-GB to work at higher temperature and pH ranges will help in using this consortium for removal of the dye from textile effluent. Malt extract, peptone and beef extract were found to be the best additional carbon and nitrogen sources. Brilliant Blue G caused enhancement of the riboflavin reductase among the enzyme activities studied. Biodegradation was confirmed by analyzing the product using UV–vis, HPLC, and FTIR. The GC–MS study revealed a pathway of Brilliant Blue G with release of (4-ethoxy-phenyl)-phenyl-amine and 3-ethylaminomethyl-benzenesulfonic acid as final metabolites formed by the consortium-GB. GC–MS analysis indicated the formation of 3-{[ethyl-(3-methyl-cyclohexa-2,5-dienyl)-amino]-methyl}-benzenesulfonic acid as a product by G. geotrichum MTCC 1360 alone and (4-benzylidene-3-methyl-cyclohexa-2,5-dienylidene)-methyl-amine by Bacillus sp. VUS alone. Phytotoxicity revealed nontoxic nature of the metabolites. These results indicate the high potential of the consortium-GB to serve as an excellent biomass for the use in Brilliant Blue G dye removal.