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Zhinan Xu,Xiangting Wu,Linmei Tang,Yinming Du 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6
PEG-Dextran and PEG-salt aqueous two-phase systems (ATPS) have been applied to separate glutathione (GSH) from crude yeast extracts. Single-factor experiments were carried out to determine the important factors influencing the partition coefficient and extraction yield. The effect of PEG molecular weight, phase-forming components,PEG and Dextran concentration, pH value, and temperature on the GSH partitioning behavior in ATPS was investigated. Three factors, Dextran concentration, pH value, and temperature, were confirmed to have significant influence on the partition coefficient and extraction yield. These factors were further analyzed with the aid of central composite rotatable design and response surface methodology. The optimal conditions for GSH extraction in the PEGDextran system were determined, including PEG molecular weight 6,000, 10% PEG concentration, 14% Dextran concentration,pH 5.2, and temperature 32 oC. A high extraction yield (83.55%) of GSH from crude yeast extracts was achieved under these optimized conditions. This work is very helpful for developing one efficient and cost-effective process for the separation and purification of GSH from yeast broths.
Zhinan Xu,Feng Shi,Peilin Cen 한국생물공학회 2006 Biotechnology and Bioprocess Engineering Vol.11 No.3
The components of the media used to elicit the biosynthesis of poly-γ-glutamic acid (γ-PGA) by Bacillus subtilis ZJU-7 were investigated, particularly the carbon and nitrogen sources. Of the 7 carbon sources investigated, sucrose induced the highest rate of γ-PGA productivity; among the nitrogen sources, tryptone had the best effect for γ-PGA production. A 26-2 fractional factorial design was used to screen factors that influence γ-PGA production significantly, and a central composite design was finally adopted to formulate the optimal medium. γ-PGA productivity improved approximately 2-fold when the optimal medium was used compared with the original nonoptimized medium, and volumetric productivity reached a maximum of 58.2 g/L after a 24-h cultivation period.
Zhinan Xu,Limei Fang,Jianping Lin,Xiaoxia Jiang 한국생물공학회 2006 Biotechnology and Bioprocess Engineering Vol.11 No.1
The asymmetric biosynthesis of ethyl (S)-4-chloro-3-hydrobutanoate from ethyl 4-chloro-3-oxobutanoate was investigated by using whole cells of Candida magnoliae JX120-3 without the addition of glucose dehydrogenase or NADP+/NADPH. In a one-phase system, the bioconversion yield was seriously affected on the addition of 12.1 g/L ethyl 4-chloro-3-oxobutanoate. In order to reduce this substrate inhibition, a water/n-butyl acetate two-phase system was developed, and the bioreduction conditions optimized with regard to the yield and product enantiometric excess value. The optimal conditions were as following: water to n-butyl acetate volume ratio of 1:1, 4.0 g DCW/L active cells, 50 g/L glucose and 35°C. By adopting a dropwise substrate feeding strategy, high concentration of ethyl 4-chloro-3-oxobutanoate (60 g/L) could be asymmetrically reduced to ethyl (S)-4-chloro-3-hydrobutanoate with high yield (93.8%) and high enantiometric excess value (92.7%).
Anisotropic Characteristic of Irregular Columnar-jointed Rock Mass Based on Physical Model Test
Zhinan Lin,Weiya Xu,Huanling Wang,Jiuchang Zhang,Wang Wei,Rubin Wang,Hua Ji 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.5
Columnar joint is a special geological structure with self-organized joint network which separates the rock into an assemblage of blocks. The mechanic characteristics of irregular columnar-jointed rock mass (ICJRM) are dependent not only on the intact rock material but also on unique types of columnar joints. In effort to understand the anisotropic mechanic characteristics of ICJRM by the inherent anisotropic nature of the jointed structure, we conducted a series of uniaxial compression tests. Experiments were performed on an artificial ICJRM of 50 mm in diameter and 100 mm high. The “intact material” consisted of cement mortar and the columnar joints of photosensitive resins. The columnar joint in the specimen was made into six different orientations: 0°, 30°, 45°, 60°, 75°, and 90°, respectively, so observe the deformation behavior and failure modes of ICJRM with different various angles between the loading orientation and columnar joint were observed. Based on the analysis of the test results, the uniaxial compression strength and elastic modulus of ICJRM showed strong anisotropic behavior along with a special “U” shape in response to the angle between the loading orientation and columnar joint. Furthermore, the failure modes of ICJRM was observed.
Zhinan Lin,Weiya Xu,Wei Wang,Huanling Wang,Rubin Wang,Hua Ji,Jiuchang Zhang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.9
The strength behavior and deformation modulus of columnar jointed rock mass have been investigated by conducting a series of uniaxial compressive tests, along with consideration of columnar joint effect. The tests have been performed on the artificial physical model samples, incorporating different angles β (which was the between the loading direction and axial direction of the columns) and heights of specimen. Columnar joint is a special geological structure with self-organized joint network which separates the rock into an assemblage of blocks. Due to the special joint network, the anisotropic characteristics of columnar joint rock mass is very remarkable. The physical model consisted of “intact rock” and “jointed filler”, replaced by cement mortar and white cement, respectively. The angle β were set to 0°, 15°, 30°, 45°, 60°, 75° and 90°, respectively, and the heights of specimen were set to five different values. Through the test, failure strength and failure modes of columnar joint rock mass with different angles β were observed. Based on the analysis of the test results, the uniaxial compression strength and average modulus of columnar joint rock mass showed strong anisotropy, showing a special “U” shape in terms of loading orientation. The size effect of columnar jointed rock mass was very typical, and the failure mode of columnar joint rock mass were analyzed. Furthermore, the relationship between failure strength and joint factor was studied.
Lei Huang,Zhinan Xu,Yijuan Xiang,Jin Cai,Ling Jiang,Zhengbing Lv,Yaozhou Zhang 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.12
The effects of three main sugars in cane molasses were investigated systematically to prepare a cost-effective medium for butyric acid bioproduction. Additionally, 30 g/L corn steep liquor was screened out as the suitable nitrogen source. In the batch fermentation of free cells, when 60 g/L glucose was the only carbon source, 21.28 g/L butyric acid was achieved after 30 h cultivation. Similar product concentration, productivity and yield were obtained when 60 g/L fructose was applied. The utilization of sucrose would bring about lower productivity (0.29 g/L·h) and product concentration (18.15 g/L), but the yield of butyric acid/sucrose (0.34 g/g) is almost the same as that from glucose or fructose (0.35 g/g). Finally, the sugar mixture (15 g/L glucose, 20 g/L fructose and 35 g/L sucrose) was employed to produce butyric acid in a fibrous-bed bioreactor (FBB), and 40.11 g/L butyric acid was produced with one simple fed-batch strategy.
Shi, Feng,Xu, Zhinan,Cen, Peilin The Korean Society for Biotechnology and Bioengine 2006 Biotechnology and Bioprocess Engineering Vol.11 No.3
The components of the media used to elicit the biosynthesis of $poly-{\gamma}-glutamic$ acid $({\gamma}-PGA)$ by Bacillus subtilis ZJU-7 were investigated, particularly the carbon and nitrogen sources Of the 7 carbon sources investigated, sucrose induced the highest rate of ${\gamma}-PGA$ productivity; among the nitrogen sources, tryptone had the best effect for ${\gamma}-PGA$ production. A $2^{6-2}$ fractional factorial design was used to screen factors that influence ${\gamma}-PGA$ production significantly, and a central composite design was finally adopted to formulate the optimal medium. ${\gamma}-PGA$ productivity improved approximately 2-fold when the optimal medium was used compared with the original nonoptimized medium, and volumetric productivity reached a maximum of 58.2 g/L after a 24-h cultivation period.
Theoretical and Experimental study on Attosecond high-order Harmonics Radiation at SIOM
Ruxin Li,Xinhua Xie,Zhinan Zeng,Zhizhan Xu 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.32
Phase-matched high-order harmonic generation in an Ar gas-lled cell was investigated experimentally. We found that the spatial prole of high-order harmonics under the phase-matching condition was quite dierent from that of the phase-mismatching case. Also, the scheme of highintensity attosecond high-order harmonic generation driven by a synthesized laser eld is proposed. This new scheme provides a possible approach for producing a high-energy attosecond XUV pulse, which is useful for nonlinear attosecond spectroscopy.
Yisong Chen,Fengxiang Xu,Suo Zhang,Kunying Wu,Zhinan Dong 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.2
Tailor-welded blanks (TWBs) thin-walled structures have been widely applied in field of automotive and construction due to their significant advantages in saving weight and improving crashworthiness. To further understand and improve crashing performance of TWB structures, this paper conducts parametric analysis and optimization design on TWB thin-walled tubes. Firstly, the numerical model of dynamic crashing event of different TWB tubes is derived from physical experiments. The parametric analysis results show that the material and thickness combinations have significant effects on the crashing performance. The energy-absorbed characteristics and deformed modes of TWBs are superior to those of tubes with uniform thickness. Then, two optimization cases of TWB tubes are presented through analysis of mean (ANOM) and updating orthogonal array, in which the thickness property and material types are considered as design variables. The results demonstrated that the performances of the optimized structure are much better than those of the initial counterpart.