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Synthesis of TiO2 supported on activated carbon by MOCVD: operation parameters study
ZHANG Xing-wang, ZHOU Ming-hua, LEI Le-cheng, XU Su
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(12): 1548-1553.
https://doi.org/10.1631/jzus.2004.1548
The metallo-organic chemical vapor deposition (MOCVD) technique has been applied to the preparation of the photocatalyst titanium dioxide supported on activated carbon. The effects of various condition parameters such as carrier gas flow rate, source temperature and deposition temperature on the deposition rate were investigated. The maximum deposition rate of 8.2 mg/(g·h) was obtained under conditions of carrier gas flow rate of 400 ml/min, source temperature of 423 K and deposition temperature of 913 K. The deposition rate followed Arrhenius behavior at temperature of 753 K to 913 K, corresponding to activation energy Ea of 51.09 kJ/mol. TiO2 existed only in anatase phase when the deposition temperature was 773 K to 973 K. With increase of deposition temperature from 1073 K to 1273 K, the rutile content sharply increased from 7% to 70%. It was found that a deposition temperature of 773 K and a higher source temperature of 448 K resulted in finely dispersed TiO2 particles, which were mainly in the range of 10~20 nm.
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Performance of PAHs emission from bituminous coal combustion
YAN Jian-hua, YOU Xiao-fang, LI Xiao-dong, NI Ming-jiang, YIN Xue-feng, CEN Ke-fa
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(12): 1554-1564.
https://doi.org/10.1631/jzus.2004.1554
Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion.
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Effect of temperature on batch elastase production by Bacillus sp. EL31410
HE Guo-qing, XU Ying, CHEN Qi-he, RUAN Hui, LI Jing-jun
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(12): 1583-1589.
https://doi.org/10.1631/jzus.2004.1583
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 °C to 28 °C, were evaluated in shake flask. The result indicated that 37 °C was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 °C. This result was verified by batch fermentation in 5-L bioreactor under 37 °C and 30 °C temperature, respectively. The specific cell growth rate at 37 °C was higher than that at 30 °C during earlier stage of cultivation. The maximum value [5.5 U/(h·g DCW)] of elastase formation rate occurred at 24 h at 30 °C compared to 4.6 U/(h·g DCW) at 30 h at 37 °C. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 °C or 30 °C, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 °C, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 °C in batch process. It was concluded that cultivation at constant temperature of 30 °C was appropriate for elastase production by Bacillus sp. EL31410.
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Enhancing the quality metric of protein microarray image
WANG Li-qiang, NI Xu-xiang, LU Zu-kang, ZHENG Xu-feng, LI Ying-sheng
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(12): 1621-1628.
https://doi.org/10.1631/jzus.2004.1621
The novel method of improving the quality metric of protein microarray image presented in this paper reduces impulse noise by using an adaptive median filter that employs the switching scheme based on local statistics characters; and achieves the impulse detection by using the difference between the standard deviation of the pixels within the filter window and the current pixel of concern. It also uses a top-hat filter to correct the background variation. In order to decrease time consumption, the top-hat filter core is cross structure. The experimental results showed that, for a protein microarray image contaminated by impulse noise and with slow background variation, the new method can significantly increase the sig-nal-to-noise ratio, correct the trends in the background, and enhance the flatness of the background, the consistency of the signal intensity.
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19 articles
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