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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2007年第11期8卷 845-852页

作者： CHEN Qi-he ruan hui ZHANG Hai-feng NI hui HE Guo-qing Department of Food Science and Nutrition Zhejiang University Hangzhou 310029 China School of Bioengineering Jimei University Xiamen 361021 China

Sequential methodology based on the application of three types of experimental designs was used to optimize the fermentation conditions for elastase production from mutant strain ZJUEL31410 of Bacillus licheniformis in shaking flask cul- tures. The optimal cultivation conditions stimulating the maximal elastase production consist of 220 r/min shaking speed, 25 h fermentation time, 5% (v/v) inoculums volume, 25 ml medium volume in 250 ml Erlenmeyer flask and 18 h seed age. Under the optimized conditions, the predicted maximal elastase activity was 495 U/ml. The application of response surface methodology resulted in a significant enhancement in elastase production. The effects of other factors such as elastin and the growth factor (corn steep flour) on elastase production and cell growth were also investigated in the current study. The elastin had no significant effect on enzyme-improved production. It is still not clear whether the elastin plays a role as a nitrogen source or not. Corn steep flour was verified to be the best and required factor for elastase production and cell growth by Bacillus licheniformis ZJUEL31410.

关键词： Elastase Bacillus licheniformis ZJUEL31410 Cultivation condition Fractional factorial design (FFD) Response surface methodology

Microstructures of mechanically activated Ti-46at.%Al powders and spark plasma sintered ultrafine TiAl alloy

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Rare Metals 2007年第6期26卷 572-577页

作者： XIA Li DING hui ruan Xuefong REN Yaoyao College of Power and Mechanical Engineering Wuhan University Wuhan 430072 China School of Physicals Wuhan University Wuhan 430072 China

Powder of Ti-46at.%Al was synthesized through mechanical activation （MA） for different milling times, and the 16 h MAed powder was sintered by using a spark plasma sintering （SPS） process at different sintering temperatures. The XRD profiles showed that the MAed Ti-46at,%Al powder for 12, 16, and 20 h contained initial α-Ti and Al phases, and that the SPSed TiAl alloys contained the gamma TiAl and α2-Ti3Al phases. The TEM showed two different types of regions in the 16 h MAed Ti-46at.%Al powder. One type consisted of only Al with a grain size about 80 nm, and the other type a mixture of Al and Ti with a grain size of 30 nm. According to the optical micrographs of MA-SPSed samples, the alloys sintered at higher temperatures showed a coarser microstructure. In the case of the 1473 Ksintering, typical duplex structures （（α2 ＋γ） lamella and γ phases） with interlamellar spacings of 50-400 nm and the grain size either less than 100 nm, or 1000 nm were observed.

关键词： metal materials titanium aluminides spark plasma sintering (SPS) mechanical activation (MA)

Study on swelling model and thermodynamic structure of native konjac glucomannan

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第4期10卷 273-279页

作者： Long LI hui ruan Liu-liu MA Wei WANG Ping ZHOU Guo-qing HE Department of Food Science and Nutrition College of Biosystem Engineering and Food Science Zhejiang University Hangzhou 310029 China Department of Food Science and Technology Guangdong Shaoguan College Shaoguan 512005 China

We investigated the higher structure of konjac glucomannan (KGM) in the amorphous state and solution using a laser particle size analyzer and a water activity meter. The results show that the thermodynamic structures of native KGM were primarily composed of the lamella structure units, which involve both granular crystalline and amorphous regions, and that the connection zones of such units contained both loose and tight aggregation regions. The value of surface tension (σ) of native KGM, resting with the density of its hydroxyl groups' self-association, was an important parameter to analyze the higher structures of native KGM in the thermodynamic swelling model of native KGM.

关键词： Swelling model Thermodynamic structure Konjac glucomannan (KGM) Higher structure

Effects of aging treatment processes on microstructures and mechanical properties of AZ63 casting magnesium alloy

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China Foundry 2023年第4期20卷 307-314页

作者： Chun-yu Li Hao-bo Wei Shi-hui ruan Jie-yi Chen Zong-gang Wu Ming-bo Yang Materials Science&Engineering College Chongqing University of TechnologyChongqing 400050China

The effects of three different aging treatment processes,namely single-stage,double-stage,and reverse double-stage aging treatment processes,on the microstructures and mechanical properties of the AZ63(Mg-6Al-3Zn-0.25Mn)casting magnesium alloy were investigated and *** results indicate that the microstructures of all the aged alloys under the three treatment processes are mainly composed ofα-Mg,Mg17Al12),and Al4Mn phases,indicating that the double-stage and reverse double-stage aging treatments have no obvious effect on the type of alloy ***,as compared with the single-stage and double-stage processes,the reverse double-stage process has a great effect on the quantity of the *** the reverse double-stage aging treatment,which results in a stronger drive for decomposition of the supersaturated solid solution,the number of Mg17Al12phases precipitated in the grains significantly *** addition,as compared with the single-stage aged alloy,the tensile properties at room temperature for both the double-stage and reverse double-stage aged alloys are significantly *** them,the reverse double-stage aged alloy achieves the highest tensile strength,yield strength,and elongation of 295 MPa,167 MPa,and 8.6%,respectively.

关键词： magnesium alloys Mg-Al based alloys AZ63 alloy heat treatment aging treatment

Production of conjugated linoleic acids by Lactobacillus plantarum strains isolated from naturally fermented Chinese pickles

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2011年第11期12卷 923-930页

作者： Pei LIU Sheng-rong SHEN hui ruan Qian ZHOU Liu-liu MA Guo-qing HE School of Biosystems Engineering and Food Science Zhejiang University Hangzhou 310058 China College of Food Science and Engineering Shandong Agricultural University Tai ＇an 271018 China

Naturally fermented pickles harbour many lactic acid bacteria （LAB）. Forty-three LAB strains with conjugated linoleic acid （CLA）-producing ability were isolated from three naturally fermented pickle brines. Of these isolates, Ip15 identified as Lactobacillus plantarum by API 50 CHL system and full-length 16S rDNA sequence analysis exhibited the highest CLA-producing ability （26.1% conversion） at 48 h in de Man Rogosa Sharpe （MRS） broth in the presence of 100 IJg/ml of linoleic acid （LA）. Compared to other strains, L. plantarum strain Ip15 showed the highest tolerance upon increased levels of LA in the medium, i.e., up to 600 μg/ml. This strain converted about 25% of LA into CLA isomers [predominantly cis-9, trans-11 CLA （9-CLA） and trans-lO, cis-12 CLA （10-CLA）], of which 75% was 9-CLA. Interestingly, though the conversion rate of LA into CLA by Ip15 remained stable between 100 to 600μg/ml LA levels in the medium, it dropped sharply at 1000 μg/ml. Taken together, the Ip15 strain displayed relatively high LA tolerance with higher conversion rate, which implies that this strain is a valuable candidate for enhancing the CLA content in food-sources like pickles.

关键词： Conjugated linoleic acids Lactobacillus plantarum Lactic acid bacteria Pickle Gas chromatography

Implications of Necroptosis for Cardiovascular Diseases

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Current Medical Science 2019年第4期39卷 513-522页

作者： Zhao-hui ruan Zi-xuan XU Xue-yun ZHOU Xian ZHANG Lei SHANG Jiangxi Research Institute of Ophthalmology and Visual Sciences Affiliated Eye Hospital of Nanchang UniversityNanchang

Necroptosis is a non-apoptotic programmed cell death pathway,which causes necrosislike morphologic changes and triggers inflammation in the surrounding *** evidence has demonstrated that necroptosis is involved in a number of pathological processes that lead to cardiovascular ***,the exact molecular pathways linking them remain ***,this review summarizes the necroptosis-related pathways involved in the development of various cardiovascular diseases,including atherosclerosis,cardiac ischemia-reperfusion injury,cardiac hypertrophy,dilated cardiomyopathy and myocardial infarction,and may shed light on the diagnosis and treatment of these diseases.

关键词： cell death death-associated molecular patterns necroptosis cardiovascular disease

Numerical simulation on centrifugal pump compressible flow field with different gas volume fractions

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排灌机械工程学报 2019年第2期37卷 106-111,129页

作者： WANG Like LIAO Weili LU Jinling LUO Xingqi ruan hui ZHAO Yaping WANG Jing Institute of Water Resource and Hydro-electric Engineering Xi'an University of Technology

In order to study the influence of gas-liquid two-phase flow on the performance and internal flow field of a centrifugal pump,the steady three-dimensional flow with different gas volume fractions was simulated by applying the Reynolds-average N-S equation and mixture gas-liquid two-phase flow model,and the compressibility of gas was taken into consideration in the simulation. Then the centrifugal pump characteristic and the gas distribution law in different gas volume fractions were analyzed. The computational results show that gas volume fraction has a certain influence on the performance of the centrifugal pump,and the efficiency and head of the pump are on the decline with the increase of *** pressure in the impeller increases in the radial direction,but the pressure gradient in the flow direction is different under the different gas volume fractions. The gas volume is distributed mainly in the ipsilateral direction of impeller back shroud in the flow channel of the volute. On the suction side of the blade inlet there is an obvious low-pressure area,which causes bubbles agglutination and higher gas volume fraction. With the gas entering passage flow,gas volume fraction in the suction decreases and the pressure surface rises gradually. Higher gas volume fraction causes air blocking phenomenon in the flow passage and the discharge capacity reduces. The increase of gas volume makes the turbulent motion within the impeller more and more intense,which leads to more and more energy loss.

关键词： centrifugal pump Mixture model gas-liquid two-phase flow gas volume fraction compressibility

Optimization of biotransformation from phytosterol to androstenedione by a mutant Mycobacterium neoaurum ZJUVN-08

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第2期14卷 132-143页

作者： Xiao-yan ZHANG Yong PENG Zhong-rui SU Qi-he CHEN hui ruan Guo-qing HE Department of Food Science and Nutrition Zhejiang University Department of Food Science and Technology School of Agriculture and BiologyShanghai Jiao Tong University

Biotransformation of phytosterol(PS) by a newly isolated mutant Mycobacterium neoaurum ZJUVN-08 to produce androstenedione has been investigated in this *** parameters of the biotransformation process were optimized using fractional factorial design and response surface *** was the sole product in the fermentation broth catalyzed by the mutant *** ZJUVN-08 *** showed that molar ratio of hydroxypropyl-β-cyclodextrin(HP-β-CD) to PS and substrate concentrations were the two most significant factors affecting androstenedione *** analyzing the statistical model of three-dimensional surface plot,the optimal process conditions were observed at 0.1 g/L inducer,pH 7.0,molar ratio of HP-β-CD to PS 1.92:1,8.98 g/L PS,and at 120 h of incubation *** these conditions,the maximum androstenedione yield was 5.96 g/L and nearly the same with the non-optimized(5.99 g/L),while the maximum PS conversion rate was 94.69% which increased by 10.66% compared with the non-optimized(84.03%).The predicted optimum conditions from the mathematical model were in agreement with the verification experimental *** is considered that response surface methodology was a powerful and efficient method to optimize the parameters of PS biotransformation process.

关键词： Phytosterol Mycobacterium neoaurum ZJUVN-08 Androstenedione Hydroxypropyl-β-cyclodextrin

Enhancement of the thermostability of β-1,3-1,4-glucanase by directed evolution

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第11期7卷 1948-1955页

作者： ZHANG Xiu-yan ruan hui MU Lin HE Guo-qing TANG Xing-jun CHEN Qi-he Department of Food Science and Nutrition Zhejiang University Hangzhou 310029 China

In order to improve the thermostability of β- 1,3-1,4-glucanase, evolutionary molecular engineering was used to evolve the β-1,3-1,4-glucanase from Bacillus subtilis ZJF-1A5. The process involves random mutation by error-prone PCR and DNA shuffling followed by screening on the filter-based assay. Two mutants, EGsl and EGs2, were found to have four and five amino acid substitutions, respectively. These substitutions resulted in an increase in melting temperature from Tm=62.5℃ for the wild-type enzyme to Tm=65.5℃ for the mutant EGsl and 67.5℃ for the mutant EGs2. However, the two mutated enzymes had opposite approaches to produce reducing sugar from lichenin with either much higher （28%） for the former or much lower （21.6%） for the latter in comparison with their parental enzymes. The results demonstrate that directed evolution is an effective approach to improve the thermostability of a mesophilic enzyme.

关键词： Directed evolution Error-prone PCR DNA shuffling β- 1 3-1 4-glucanase Thermostability

Effects of proteinase A on cultivation and viability characteristics of industrial Saccharomyces cerevisiae WZ65

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第10期10卷 769-776页

作者： Hong-bo ZHANG Hai-feng ZHANG Qi-he CHEN hui ruan Ming-liang FU Guo-qing HE Department of Food Science and Nutrition Zhejiang University Hangzhou 310029 China

Proteinase A （PrA）, encoded by PEP4 gene, is a key enzyme in the vacuoles of Saccharomyces cerevisiae. We characterized the effects of PrA on cell growth and glucose metabolism in the industrial S. cerevisiae WZ65. It was observed that the lag phase of cell growth of partial PEP4 gene deletion mutant （36 h） and PrA-negative mutant （48 h） was significantly extended, compared with the wild type strain （24 h）（P〈0.05）, but PrA had no effect on glucose metabolism either under shaking or steady state cultivations. The logistic model was chosen to evaluate the effect of PrA on S. cerevisiae cell growth, and PrA was found to promote cell growth against insufficient oxygen condition in steady state cultivation, but had no effect in shaking cultivation. The effects of glucose starvation on cell growth of partial PEP4 gene deletion strain and PrA-negative mutant were also evaluated. The results show that PrA partial deficiency increased the adaption ofS. cerevisiae to unfavorable nutrient environment, but had no effect on glucose metabolism under the stress of low glucose. During heat shock test, at 60 ℃ the reduced cell viability rate （RCVR） was 10% for the wild type S. cerevisiae and 90% for both mutant strains （P〈0.01）, suggesting that PrA was a negative factor for S. cerevisiae cells to survive under heat shock. As temperatures rose from 60 ℃ to 70℃, the wild type S. cerevisiae had significantly lower relative glucose consumption rate （RGCR）（61.0% and 80.0%） than the partial mutant （78.0% and 98.5%） and the complete mutant （80.0% and 98.0%）（P〈0.05）, suggesting that, in coping with heat shock, cells of the PrA mutants increased their glucose consumption to survive. The present study may provide meaningful information for brewing industry; however, the role of PrA in industrial S. cerevisiae physiology is complex and needs to be further investigated.

关键词： Proteinase A (PrA) PEP4 gene Saccharomyces cerevisiae WZ65 Cell metabolism Viability