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, Volume 6 Issue 6   
Biotechnology
Preparation, crystallization and preliminary X-ray diffraction analysis of PH1948, predicted RNA methyltransferase from Pyrococcus horikoshii
GAO Yong-gui, YAO Min, TANAKA Isao
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2005, 6(6): 454-456.   https://doi.org/10.1631/jzus.2005.B0454
Abstract   PDF (0KB)
RNA methyltransferase is responsible for transferring methyl and resulting in methylation on the bases or ribose ring of RNA, which existed widely but mostly remains an open question. A recombinant protein PH1948 predicting RNA methyltransferase from Pyrococcus horikoshii OT3 has been crystallized. The crystals of selenomethionyl PH1948 belong to space group C2, with unit-cell parameters a=207.0 Å, b=43.1 Å, c=118.2 Å, β=92.1°, and diffract X-rays to 2.2 Å resolution. The VM value was determined to be 2.8 Å3/Da, indicating the presence of four protein molecules in the asymmetric unit.
Pathogenicity of bacterium, Xenorhabdus nematophila isolated from entomopathogenic nematode (Steinernema carpocapsae) and its secretion against Galleria mellonella larvae
MAHAR Ali Nawaz, MUNIR Muhammad, ELAWAD Sami, GOWEN Simon Richard, HAGUE Nigel Graham Meckenzi
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2005, 6(6): 457-463.   https://doi.org/10.1631/jzus.2005.B0457
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The entomopathogenic bacterium, Xenorhabdus nematophila was isolated from the hemolymph of Galleria mellonella infected with Steinernema carpocapsae. The bacterial cells and its metabolic secretions have been found lethal to the Galleria larvae. Toxic secretion in broth caused 95% mortality within 4 d of application whereas the bacterial cells caused 93% mortality after 6 d. When filter and sand substrates were compared, the later one was observed as appropriate. Similarly, bacterial cells and secretion in broth were more effective at 14% moisture and 25 °C temperature treatments. Maximum insect mortality (100%) was observed when bacterial concentration of 4×106 cells/ml was used. Similarly, maximum bacterial cells in broth (95%) were penetrated into the insect body within 2 h of their application. However, when stored bacterial toxic secretion was applied to the insects its efficacy declined. On the other hand, when the same toxic secretion was dried and then dissolved either in broth or water was proved to be effective. The present study showed that the bacterium, X. nematophila or its toxic secretion can be used as an important component of integrated pest management against Galleria.
Application of least squares vector machines in modelling water vapor and carbon dioxide fluxes over a cropland
QIN Zhong, YU Qiang, LI Jun, WU Zhi-yi, HU Bing-min
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2005, 6(6): 491-495.   https://doi.org/10.1631/jzus.2005.B0491
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Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a summer maize field using the dataset obtained in the North China Plain with eddy covariance technique. The performances of the LS-SVMs were compared to the corresponding models obtained with radial basis function (RBF) neural networks. The results indicated the trained LS-SVMs with a radial basis function kernel had satisfactory performance in modelling surface fluxes; its excellent approximation and generalization property shed new light on the study on complex processes in ecosystem.
Environmental Sciences
Isobaric vapor-liquid equilibrium for methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system
QIU Zu-min, XIE Xin-liang, LUO Mei, XIE Feng-xia
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2005, 6(6): 559-562.   https://doi.org/10.1631/jzus.2005.B0559
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This paper describes measurement of vapor-liquid equilibrium (VLE) data of methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system and that of the three binary systems at 101.325 kPa with a new pump-ebulliometer. The equilibrium composition of the vapor phase was calculated from pTx by indirect method. The model parameters of the liquid activity coefficient of the Wilson, NRTL, Margules and van Laar equations was corrected by the least square method. The ternary system VLE data were predicted by the Wilson equation, with the calculated boiling points showing good agreement with the experimental data.
Dechlorination by combined electrochemical reduction and oxidation
CONG Yan-qing, WU Zu-cheng, TAN Tian-en
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2005, 6(6): 563-568.   https://doi.org/10.1631/jzus.2005.B0563
Abstract   PDF (0KB)
Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electrochemical reduction and oxidation at current of 6 mA and pH 6. The hydrogen atom is a powerful reducing agent that reductively dechlorinates chlorophenols. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the degradation of chlorophenol.
Fe salts as catalyst for the wet oxidation of o-chlorophenol
XU Xin-hua, HE Ping, JIN Jian, HAO Zhi-wei
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2005, 6(6): 569-573.   https://doi.org/10.1631/jzus.2005.B0569
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Catalytic wet air oxidation (CWAO) of o-chlorophenol in wastewater was studied in a stainless steel autoclave using four different Fe catalysts in the temperature range of 100–200 °C. Experimental results showed that high rate of o-chlorophenol and CODCr (Chemical Oxygen Demand, mg/L) removal by CWAO was obtained at relatively low temperature and pressure. The catalysts Fe2(SO4)3, FeSO4, Fe2O3 and FeCl3 all exhibited high catalytic activity. More than 93.7% of the initial CODCr and nearly 100% of o-chlorophenol were removed at 150 °C after 150 min with FeSO4 as catalyst. The CWAO of o-chlorophenol was found to be pseudo-first order reaction with respect to o-chlorophenol, with activation energy of 75.56 kJ/mol in the temperature range of 100–175 °C.
Materials and Chemical Engineering
A study on naphtha catalytic reforming reactor simulation and analysis
Liang Ke-min, GUO Hai-yan, PAN Shi-wei
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2005, 6(6): 590-596.   https://doi.org/10.1631/jzus.2005.B0590
Abstract   PDF (0KB)
A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.
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