2020 Vol. 35, No. 3
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Using genetic engineering techniques,the recombinant plasmid pPICZαA-AoFT was linearized,and then electroporated into Pichia pastoris X33 to construct recombinant Pichia pastoris engineering strain pPICZαA-AoFT/X33 and achieve the recombinant fructosyl transferase AoFT in Pichia pastoris.Furthermore,the enzymatic properties of the purified fructosyl transferase AoFT were studied.The results showed that the pPICZαA-AoFT/X33 multiplied rapidly with the increase of fermentation time.The OD600 value of the cell reached a peak at 120 h,and the total protein concentration of the extracellular protein in the fermentation broth was 1.64 mg/mL.The specific activity of the purified fructosyl transferase AoFT enzyme was 71.4 U/mg,and the yield was 70.6%.The peptide N-glycosidase F digestion reaction confirmed that the purified fructosyl transferase AoFT had some N-glycosylation sites.The optimal reaction temperature of fructosyl transferase AoFT was 45 ℃,and the optimal buffer system was sodium acetate buffer (pH value was 4.5~6.0).Metal ions Mn2+ and Ca2+ could activate fructosyl transferase AoFT,while Al3+,Fe2+,Ni2+,Zn2+ and EDTA could inhibit fructosyl transferase AoFT.Surfactants (SDS,Tween-20 and Triton X-100) had little effect on the activity of fructosyl transferase AoFT,while the reductant DTT had obvious inhibition effect on the activity of fructosyl transferase AoFT.The low concentration of PMSF had no significant effect on the activity of fructosyl transferase,but the high concentration could reduce the activity.The activity of fructosyl transferase AoFT showed strong resistance to organic solvents (ethanol,DMSO,dimethylformamide,n-butanol,n-hexane and toluene).
For 3 common plant fungal diseases of cucumber fusarium wilt pathogen (cucumber fusarium oxysporum), tobacco brown spot pathogen (red star mould) and Chinese milk vetch root rot pathogen(Chinese milk vetch root rot fungus),10 yeast strains with strong antagonistic effect were screened out from 81 isolated and preserved yeast strains by plate confrontation method. The classification status of the yeast strains was determined by analyzing morphological characteristics, physiological and biochemical characteristics and gene sequencing analysis. The results showed that WYCCW10371 had the best antagonistic effect against the cucumber fusarium oxysporum, its bacteriostatic rate was 46.2%,which was identified as Hanseniaspora vineae; WYCCW10196 had the best antagonistic effect against the red star mould, its bacteriostatic rate was 30.6%,which was identified as Starmerella bacillusaris;WYCCW11142 had the best antagonistic effect against the Chinese milk vetch root rot fungus, its bacteriostatic rate was 20.7%, which was identified as Pichia terricola.
Based on the SSR molecular marking technology, it analyzed the level of genetic diversity of 7 tested tea plant varieties from Fujian province and constructed the molecular fingerprint of them. The results showed that all of the 14 molecular markers primary screening were polymorphic markers with rich polymorphism information, and 7 tested tea plant varieties could be distinguished effectively. Genetic similarity coefficient between Fuyun No.6 and Fuyun No.7 was highest(8.06) which had a close phylogenetic relationship. 3 SSR molecular markers(PS3, PS15, PS19) were selected to construct fingerprint because of less amplified bands and higher Polymorphism, and the fingerprint could distinguish 7 tea plant varieties, achieved the purpose of identifying all varieties with the least molecular marker.
Using V2O5 as raw material, oxalic acid as reducing agent, a series of nano-VO2 (B) samples with different oxalic acid concentrations (c(H2C2O4)/c(V2O5)=x,1.00≤x≤2.50) were prepared by hydrothermal method. The structure, micro-morphology and electrochemical performance of the prepared samples were characterized and analyzed. The results showed that the prepared samples were all pure phase VO2 (B) with monoclinic structure; with the increase of the concentration of reducing agent, the morphology of the VO2 (B) sample gradually changed from smaller nanoplates to larger nanorods; the structural defects of VO2 (B) samples were mainly micropores; the obtained VO2 (B) samples all had good cycle stability and reversibility. Among them, the VO2 (B) sample obtained with x=1.75 had smaller redox peak potential difference (0.111 V) and smaller resistance (0.770 Ω), and when the current density was 30 mA/g, the VO2 (B) sample had the largest specific capacitance value, 105.00 F/g, showing better electrochemical performance.
Using polyaniline (PANI) as the matrix and carbon source, ZnCl2 and FeCl3 as the metal sources, ZnFe2O4 spinel compounds were synthesized in situ on the surface of PANI by hydrothermal method. The ZnFe2O4/N-C catalyst was prepared after carbonization at high temperature, its structure and morphology were characterized and analyzed, and the effect of carbonization temperature on the structure and performance of the catalyst was investigated. The results showed that the N-C in the catalyst ZnFe2O4/N-C mainly existed in the form of amorphous carbon. The ZnFe2O4 particles were highly dispersed on the N-C surface, and with the increase of the carbonization temperature, the crystallinity of ZnFe2O4 gradually increased; the introduction of ZnFe2O4 was beneficial to the catalyst ZnFe2O4/N-C graphitization degree, when n(Fe) : n(Zn)=2 : 1, the total concentration of metal ions was 0.1 mol/L, and the carbonization temperature was 800 ℃, the ID/I</i>G (the peak D-to-G peak ratio)value of the obtained catalyst ZnFe2O4/N-C-800 was 0.97, which was lower than the ID/IG value of N-C (1.12), and it had good catalytic performance for both hydrogen evolution and oxygen evolution reactions of electrolyzed water.
Using manganese acetate, zinc acetate and self-made graphene oxide as raw materials, ZnMn2O4/RGO composites were prepared by solvothermal method and hydrothermal method, respectively, and their electrochemical properties were studied comparatively. The results showed that the addition of RGO increased the specific surface area of the ZnMn2O4/RGO composites and improved the electrochemical properties of the ZnMn2O4 material; under the condition of a current density of 2 A/g, the ZnMn2O4/RGO composites prepared by solvothermal method and hydrothermal method had specific capacitances of 763.4 F/g and 127.8 F/g, respectively. After 500 cycles of experiments, the capacitance retention rates of the composites made by these two methods were 84.9% and 83.0%, respectively. The ZnMn2O4/RGO composites made by thermal method had better comprehensive properties.
Four kinds of pre-drying treatment technology:water cleaning,ethanol cleaning,water cleaning after calcification treatment and ethanol cleaning after calcification treatment,were used to dry the breakable capsule and select the appropriate pre-drying treatment technology.The influence of calcification concentration on the particle size and crushing strength of the breakable capsule was analyzed,and the calcification concentration in the process of calcification before the breakable capsule drying was determined.The results showed that the water cleaning after calcification treatment was the appropriate pre-drying treatment technology for breakable capsule,and 0.3% was the appropriate calcification concentration.The use of the pre-drying treatment technology and calcification concentration could shorten the drying time of wet breakable capsule,reduce energy consumption,and improve the production efficiency and the consistency of finished breakable capsule products.
SDE-GC-MS was used to determine the content of flavor components in flue-cured tobacco leaves of suitable storage period in Chongqing tobacco-growing areas, and descriptive statistical analysis was carried out for the determined flavor components. Principal component analysis was used to screen the characteristic indexes of flavor components, and the difference significance analysis, multiple comparison and cluster analysis were carried out for the selected characteristic indexes. The results showed that there were significant differences in the content of 63 flavor components in tobacco leaves, and the variation coefficients of flavor components in upper and middle tobacco leaves were 12.12%~59.97% and 10.41%~73.25% respectively. There were significant differences in the region, aged time, cultivar, and grade of tobacco leaves, and the influence degree of different factors were region>aged time>cultivar>grade, but there was almost no significant difference among the grades within the position. Characteristic index content of flavor components in upper tobacco leaves of Fengdu was higher, Fuling was the second, Wulong was the lowest.Characteristic index content of flavor components in middle tobacco leaves of Qianjiang was higher, Nanchuan was the second, Wulong was the lowest. The upper and middle tobacco leaves were divided into three categories.The first category of upper tobacco leaves includes Fengdu and Nanchuan, the second category includes Wulong, Pengshui and Qianjiang, the third category is Fuling.The first category of middle tobacco leaves includes Fengdu, Nanchuan and Qianjiang, the second category includes Wulong and Fuling, and the third category includes Pengshui, with high significant differences between categories.
The research and application status of flavoring and moisturizing filter rods based on addition of additional materials (fragrance line, capsules, gel and particles) and raw materials (triacetin, wrap paper and acetate tow), and other flavoring and moisturizing filter rods were reviewed. It was pointed out that the flavoring and moisturizing filter rods based on addition of additional materials had more loading capacity and better controllability, but the principle of flavoring and moisturizing as well as the overall impact on cigarette quality were still lack of systematic research. The preparation process of the flavoring and moisturizing filter rods based on addition of raw materials was simple and the cost was low, but the loading capacity of the additive was small and it was easy to volatilize.So it was suitable to be an auxiliary means of flavoring and moisturizing. By optimizing the structure of the filter rod and adding the auxiliary agent to the other carriers, the other flavoring and moisturizing filter rods had more function of the filter rod and better controllability.However the structure was complex, the production cost was high and the quality control was difficult. These flavoring and moisturizing filter rods had some problems, such as imperfect production technology, unstable product quality control and high production cost. The future research can integrate the existing technical means and adopt the multi-element filter rod structure to effectively improve the fragrance and moisture retention performance of the filter rod. At the same time, It can also optimize the production process of filter rod to reduce the production cost and improve the quality stability of filter rod.
Through numerical simulation method which combined Moldflow software with orthogonal experiment,the residual stress distribution after demoulding in the thickness direction of three typical positions of polycarbonate corner window plastic parts was studied, and the injection compression molding process of corner window plastic parts was optimized. On the basis, the main factors were selected to investigate the influence of the main process parameters on the residual stress of the product.The results showed that the residual stress distribution after demoulding in the thickness direction of three typical locations of the product conforms to the three-region distribution of tension-compression-tension.The optimum combination of process parameters was that the mold temperature was 105 ℃, the melt temperature was 315 ℃, the injection time was 3 s, the compression force was 882 kN, the compression distance was 1.0 mm, the compression speed was 5 mm/s, and the delay time was 0 s.Melt temperature, delay time, compression distance were the main process parameters that affect the residual stress of the product, and the residual stress of the subsurface layer and the center layer of the plastic part decreased with the increase of the melt temperature, while the residual stress of each layer in the thickness direction of the plastic part increased with delay time and compression distance.
Aiming at the singular configuration of 3-RSR parallel mechanism in the process of motion, a new method based on the theory of screw, geometric algebra and space linear geometry theory was proposed to analyze the singularity of 3-RSR parallel mechanism in the full-attitude and multi-motion mode.The method first used screw theory to find the 3-RSR complete Jacobin matrix of parallel mechanism, and then represented the anti-screw of each branch of the mechanism by algebraic method and geometric mapping method.The singularity diagram of the mechanism in the fixed mode was obtained to make the singularity analysis of the full-attitude and multi-motion mode, combining with the space linear geometry theory to analyz the anti-screw correlation. The results showed that this method could more concisely and intuitively represent the singular configuration of 3-RSR parallel mechanism in two motion modes, and it did not need a lot of calculation. It was also suitable for solving the singular configuration of other multi-mode mobile parallel mechanisms.
Aiming at the problem of idle time utilization and conflict of discrete processing equipment generated by flexible job shop scheduling in cloud manufacturing environment, a flexible job shop scheduling scheme in cloud manufacturing environment based on hybrid genetic algorithm was proposed.Under the premise of ensuring the smooth completion of workshop tasks, the residual capacity of the workshop was defined and then packaged and released to the cloud platform. Taking the minimum penalty total cost as the goal,combined with the actual situation of workshop production scheduling, the cloud order tasks were selected to process together, and the genetic variable neighborhood hybrid algorithm was used to solve the optimal scheduling sequence of cloud tasks, and the optimal scheduling scheme was formulated. The benchmark test results showed that the scheme realized the collaborative production of workshop production tasks and cloud platform tasks, and improved the enterprise's revenue and resource utilization.
Founded in 1986, bimonthly
Administered by:The Education Department Henan Province
Sponsored by:Zhengzhou University of Light Industry
Editor-in-chief:Wei Shizhong
Executive Editor-in-Chief:Zou Lin
Deputy Editor-in-Chief:Qu Shuanghong
Edited & published by:Editorial Department of Journal of Light Industry
CN 41-1437/TS
ISSN 2096-1553
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Postal Code:450001
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