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Ethene/norbornene copolymerization by [Me2Si(3-tertBuCp)(NtertBu)]TiCl2/MAO-catalyst
TRAN Phu-Dennis, KAMINSKY Walter
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 121-130.
https://doi.org/10.1631/jzus.2003.0121
Ethene/norbornene copolymerization by the catalyst system [Me2Si(3-tertBuCp)(NtertBu)]TiCl2/MAO was investigated in detail at 30°C, 60°C, and 90°C. A mass flow controller was used in this work to obtain kinetic data and investigate temperature\'s effects on activity, norbornene incorporation, copolymerization parameter, microstructure, glass transition temperature, and molar masses were described. High copolymerization values rE and high alternation are determined. The number of isotactic alternating sequences is much higher than that of the syndiotactic alternating sequences.
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Lysozyme refolding at high concentration by dilution and size-exclusion chromatography
GAO Yong-gui, GUAN Yi-xin, YAO Shan-jing, CHO Man-gi
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 136-141.
https://doi.org/10.1631/jzus.2003.0136
This study of renaturation by dilution and size exclusion chromatography (SEC) addition of urea to improve yield as well as the initial and final protein concentrations showed that although urea decreased the rate of lysozyme refolding, it could suppress protein aggregation to sustain the pathway of correct refolding at high protein concentration; and that there existed an optimum urea concentration in renaturation buffer. Under the above conditions, lysozyme was successfully refolded from initial concentration of up to 40 mg/mL by dilution and 100 mg/mL by SEC, with the yield of the former being more than 40% and that of the latter being 34.8%. Especially, under the condition of 30 min interval time, i.e. τ>2(tR2-tR1), the efficiency was increased by 25% and the renaturation buffer could be recycled for SEC refolding in continuous operation of downstream process.
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Influence of medium components on elastase production using crude sources by Bacillus sp. EL31410
HE Guo-qing, CHEN Qi-he, ZHANG Li, LIU Xiao-jie
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 142-151.
https://doi.org/10.1631/jzus.2003.0142
A newly isolated strain EL31410, producing elastase (E.C3.4.4.7) with high elastolytic activity was identified as Bacillus sp. In the medium optimization, it was found that wheat bran and soybean flour hydrosate were the best crude carbon and nitrogen source for enzyme production, respectively. Addition of corn steep flour can affect the bacterium growth and elastase production. A fractional factorial design was applied to study the main factors that affect the enzyme production, and central composite experimental design and response surface methodology were adopted to derive a statistical model for the effect of wheat bran and soybean flour hydrosate on elastase production. The experimental results showed that wheat bran had positive effect but soybean flour hydrosate had negative effect, on enzyme production. An initial concentration of 3.4%(w/v) wheat bran and 9.4%(v/v) soybean flour hydrosate were found to be optimal for enzyme production in batch culture. The time course of elastase production in the optimized medium composition was also described.
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A natural language user interface for fuzzy scope queries
HUANG Yan, YU Hong-feng, GENG Wei-dong, PAN Yun-he
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 152-161.
https://doi.org/10.1631/jzus.2003.0152
This paper presents a two-agent framework to build a natural language query interface for IC information system, focusing more on scope queries in a single English sentence. The first agent, parsing agent, syntactically processes and semantically interprets natural language sentence to construct a fuzzy structured query language (SQL) statement. The second agent, defuzzifying agent, defuzzifies the imprecise part of the fuzzy SQL statement into its equivalent executable precise SQL statement based on fuzzy rules. The first agent can also actively ask the user some necessary questions when it manages to disambiguate the vague retrieval requirements. The adaptive defuzzification approach employed in the defuzzifying agent is discussed in detail. A prototype interface has been implemented to demonstrate the effectiveness.
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A color based face detection system using multiple templates
WANG Tao, BU Jia-Jun, CHEN Chun
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 162-165.
https://doi.org/10.1631/jzus.2003.0162
A color based system using multiple templates was developed and implemented for detecting human faces in color images. The algorithm consists of three image processing steps. The first step is human skin color statistics. Then it separates skin regions from non-skin regions. After that, it locates the frontal human face(s) within the skin regions. In the first step, 250 skin samples from persons of different ethnicities are used to determine the color distribution of human skin in chromatic color space in order to get a chroma chart showing likelihoods of skin colors. This chroma chart is used to generate, from the original color image, a gray scale image whose gray value at a pixel shows its likelihood of representing the skin. The algorithm uses an adaptive thresholding process to achieve the optimal threshold value for dividing the gray scale image into separate skin regions from non skin regions. Finally, multiple face templates matching is used to determine if a given skin region represents a frontal human face or not. Test of the system with more than 400 color images showed that the resulting detection rate was 83%, which is better than most color-based face detection systems. The average speed for face detection is 0.8 second/image (400×300 pixels) on a Pentium 3 (800MHz) PC.
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Large eddy simulation of a particle-laden turbulent plane jet
JIN Han-hui, LUO Kun, FAN Jian-ren, CEN Ke-fa
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 175-180.
https://doi.org/10.1631/jzus.2003.0175
Gas-solid two-phase turbulent plane jet is applied to many natural situations and in engineering systems. To predict the particle dispersion in the gas jet is of great importance in industrial applications and in the designing of engineering systems. A large eddy simulation of the two-phase plane jet was conducted to investigate the particle dispersion patterns. The particles with Stokes numbers equal to 0.0028, 0.3, 2.5, 28 (corresponding to particle diameter 1 μm, 10 μm, 30 μm, 100 μm, respectively) in Re=11 300 gas flow were studied. The simulation results of gas phase motion agreed well with previous experimental results. And the simulation results of the solid particles motion showed that particles with different Stokes number have different spatial dispersion; and that particles with intermediate Stokes number have the largest dispersion ratio.
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Adaptive designs for sequential experiments
LIN Zheng-yan, ZHANG Li-xin
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 214-220.
https://doi.org/10.1631/jzus.2003.0214
Various adaptive designs have been proposed and applied to clinical trials, bioassay, psychophysics, etc.Adaptive designs are also useful in high cost engineering trials.More and more people have been paying attention to these design methods. This paper introduces several broad families of designs, such as the play-the-winner rule, randomized play-the-winner rule and its generalization to the multi-arm case, doubly biased coin adaptive design, Markov chain model.
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Inducible nitric oxide synthase expression is related to angiogenesis, bcl-2 and cell proliferation in hepatocellular carcinoma
PENG Jia-ping, ZHENG Shu, XIAO Zuo-xiang, ZHANG Su-zhan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 221-227.
https://doi.org/10.1631/jzus.2003.0221
In this study, we examined the expression of inducible nitric oxide synthase (iNOS) and vascular endothelial growth factor (VEGF) by immunohistochemical staining in 76 tissue sections collected from hepatocellular carcinoma (HCC) patients undergoing hepatectomy. Microvascular density (MVD) was determined by counting endothelial cells immunostained using anti-CD34 antibody. We performed DNA-flow cytometric analyses to elucidate the impact of iNOS and VEGF expression on the cell cycle of HCC. Most of the HCC cells that invaded stroma were markedly immunostained by iNOS antibody. The iNOS stain intensity of the liver tissue close to the tumor edge was stronger than that of HCC tissue, and the strongest was the hepatocytes closer to the tumor tissue. However, iNOS expression in 10 normal hepatic samples was undetectable. VEGF positive expression ratio was 84.8% in iNOS positive expression cases, and the ratio was 35.3% in negative cases. There was significant correlation (P=0.000) between iNOS and VEGF expression. Moreover, iNOS expression was significantly associated with bcl-2 and MVD, but without p53 expression. DNA-flow cytometric analyses showed that combined expression of iNOS and VEGF had significant impact on the cell cycle in HCC. PI (Proliferating Index) and SPF (S-phase fraction) in the combined positive expression of iNOS and VEGF group was significantly higher than that in the combined negative group. The present findings suggested that iNOS expression was significantly associated with angiogenesis, bcl-2 and cell proliferation of HCC.
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Purification and relationship with gastric disease of a 130 kDa (CagA) protein of Helicobacter pylori
YE Shao-jing, FANG Ping-chu, MAO Guo-gen, LI Chao-long, Qiu Xiang, CHEN Hai-xiang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 232-235.
https://doi.org/10.1631/jzus.2003.0232
Objective: The aims of this research were to purify and identify the 130 kDa (CagA) protein of H. pylori clinical isolate HP97002 and evaluate the relationships between the purified 130 kDa (CagA) protein and gastric diseases. Methods: The procedure for isolating the protein included 6 mol/L guanidine extract, size exclusion chromatography and elusion from gel. Sera of 68 patients with gastric diseases (44 with chronic gastritis, 15 with atrophic gastritis, 7 with peptic ulcer disease, 2 with gastric cancer) were obtained, and the serological response to CagA was studied by Western-blot using the purified protein. Results: The purified protein was 130 kDa and preserved good antigenicity and revealed basic isoelectric point about of 8.1. Among 68 sera, 43 sera could recognize the purified protein associated with chronic gastritis 47.7% (21/44),atrophic gastritis 86.7% (13/15), peptic ulcer disease 100% (7/7),gastric cancer 100% (2/2). Compared with each other, the difference was significant (χ2=13.327, P=0.004), and 130 kDa (CagA) protein was associated with severe gastric diseases (rs=0.442, P=0.001). Conclusion: The 130 kDa (CagA) protein was associated with severe gastric diseases.
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A research on the relationship between ejaculation and serum testosterone level in men
JIANG Ming, JIANG Xin, ZOU Qiang, SHEN Jin-wen
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(2): 236-240.
https://doi.org/10.1631/jzus.2003.0236
The purpose of this study is to gain understanding of the relationship between ejaculation and serum testosterone level in men. The serum testosterone concentrations of 28 volunteers were investigated daily during abstinence periods after ejaculation for two phases. The authors found that the fluctuations of testosterone levels from the 2nd to 5th day of abstinence were minimal. On the 7th day of abstinence, however, a clear peak of serum testosterone appeared, reaching 145.7% of the baseline (P<0.01). No regular fluctuation was observed following continuous abstinence after the peak. Ejaculation is the precondition and beginning of the special periodic serum testosterone level variations, which would not occur without ejaculation. The results showed that ejaculation-caused variations were characterized by a peak on the 7th day of abstinence; and that the effective time of an ejaculation is 7 days minimum. These data are the first to document the phenomenon of the periodic change in serum testosterone level; the correlation between ejaculation and periodic change in the serum testosterone level, and the pattern and characteristics of the periodic change.
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19 articles
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