Variation of Coenzyme F420 Activity and Methane Yield in Landfill Simulation of Organic Waste

A simulated landfill anaerobic bioreactor was used to characterize the anaerobic biodegradation and biogas generation of organic waste which was mainly composed of residuals of vegetables and foods. We investigated the dynamics of the coenzyme F420 activity and determined correlations between biogas yields, methane yields, methane concentration and coenzyme F420 activity. The experiment was carded out under different conditions from control without any treatment, addition of Fe^3＋, microorganism inoculation to a combination of Fe3＋ addition and inoculation at a temperature of 36±2℃. The experiment was lasted 120 d and coenzyme F420 activity was analyzed using ultraviolet spectrophotornetry. Experimental results indicated that activity of the coenzyme F420 treated by Fe and microorganism inoculation increased substantially. The waste treated by inoculation had the greatest increase. When the waste was treated by Fe^3＋, inoculation and the combination of Fe^3＋ and inoculation, biogas yields increased by 46.9%, 132.6% and 153.1%, respectively; while the methane yields increased 4, 97 and 98 times. Methane concentration varied between 0 and 6% in the control reactor, from 0 to 14% for waste treated by the addition of Fe^3＋, from 0 to 59% for waste treated by inoculation and from 0 to 63% for waste treated by Fe^3＋ addition and inoculation. Correlations between coenzyme F420 activity and biogas production, methane production and methane concentration proved to be positively significant （p〈0.05）, except for the control. Consequently, coenzyme F420 activity could be used as an index for monitoring the activity of methanogens during anaerobic biodegradation of the organic fraction of municipal solid waste.     

赤小豆芽超氧化物歧化酶的提取条件研究

采用硫酸铵分步沉淀，以40％硫酸铵饱和度去除杂蛋白，以95％硫酸铵饱和度沉淀酶蛋白。结果表明在光照下培养的赤小豆芽超氧化物歧化酶的活性比未光照的对照组提高了54％，蛋白含量提高了30％，并测得在0～0．001mg／L范围内吲哚乙酸(IAA)对赤小豆芽超氧化物岐化酶活性起显著的促进作用，随赤小豆芽长的增加，其超氧化物岐化酶的活性呈上升趋势，子叶中赤小豆芽超氧化物岐化酶的活性较高。     

饮品中超氧化物歧化酶的活性测定及影响因素

利用邻苯三酚３２５ｎｍ自氧化法研究了ＳＯＤ在不同饮品中活性的变化,结果表明：ＳＯＤ活性受饮品的色泽、成分、酸碱度、乙醇含量等多种因素的影响,在无色的、近中性饮品中ＳＯＤ活性较稳定。     

脂肪酶催化反应的研究进展

综述了脂肪酶催化特性及近年对反应体系中水、介质、载体等对脂肪酶催化活性影响的研究成果。     

重金属镉对土壤酶活性影响的研究

在试验室条件下,研究了外源添加不同浓度的重金属镉对土壤生物活性和土壤酶活性的影响.结果表明,重金属镉污染对不同的土壤生化过程具有不同效应,镉污染对土壤酶活性的影响中,对土壤的脲酶活性有很显著的抑制作用,而对过氧化氢酶、磷酸酶等活性影响较小.通过对土壤酶活性的测定得出,由于土壤脲酶对不同浓度镉表现强烈的敏感性,用脲酶作为土壤Cd污染的评价指标和制定Cd的临界含量是可行的,可为污水灌溉地区提供土壤中镉浓度的最高限值,保证污灌区的农作物食用安全和土壤的可持续利用,对地区的经济发展和环境安全有重要意义.     

纤维素酶法提取茶多糖

为了保持茶多糖的活性，采用低温水提、酶提二次结合法提取茶多糖，第一次在50℃、茶叶与水的质量比为1：15、水提取30min，多糖的提取率为2．33％，粗多糖（干重）的提取率为6．82％；过滤后，滤渣用pH4．6的柠檬酸－柠檬酸钠缓冲液加纤维素酶提取，经正交试验确定酶提最佳工艺参数为55℃、茶叶与水的质量比为1：14、酶用量2．2μL/g（以茶叶质量计），反应时间为120min，其多糖的提取率为0．64％，粗多糖（干重）的提取率为1．11％，分别占二次总提取量的21．5％和14．0％，而在相同条件下无酶提取，提取率仅为0．39％和0．56％，相对水提法，酶法的多糖提取率分别增加63．3％和98．9％，多糖总提取率达2．97％，粗多糖（干重）的总提取率为7．93％，采用酶法提取的茶多糖具有较强抑制α-淀粉酶活力的能力。     

酶活性变化在萝卜抗TuMV分析鉴定中的应用

不同萝卜品种接种抗感芜菁花叶病（ＴｕＭＶ）后,测定不同时期叶片中的过氧化物酶（ＰＯＤ）、多酚氧化酶（ＰＰＯ）、苯丙氨酸裂解酶（ＰＡＬ）的活性。结果表明,抗病品种ＰＯＤ活性的略低于感病品种,接种后ＰＯＤ活性升高;抗病品种ＰＰＯ活性比感病品种高,接种后抗病品种ＰＰＯ活性迅速升高,与抗性呈正相关,可以作为抗性大小的衡量指标,抗病品种ＰＡＬ活性比感病品种高,接种后变化无规律。     

Removal of Cr（Ⅲ） and Cr（Ⅵ） from aqueous solution by adsorption on sugarcane pulp residue

Sugarcane pulp residue (SPR), a waste from sugar-refinery, which possesses a large surface area, can be used for removing chromium (Cr(III) and Cr(VI)) from wastewater. In this work, the kinetics, isotherms of Cr(III) and Cr(VI) adsorption and their removal by SPR were investigated. The results show that the removal percentages of Cr(VI) and Cr(III) increase with increasing SPR dosage and temperature and decrease with increasing SPR particle size and the initial concentration of chromium ions. However, the influence of pH value on the Cr(VI) removal differs from that of the Cr(III) removal. The Cr(VI) removal percentage decreases with increasing pH values, while the Cr(III) removal percentage increases with increasing pH value. The adsorption kinetics of Cr(VI) and Cr(III) well fits with pseudo-second-order model. Langmuir adsorption isotherm can well describe the adsorption phenomena of chromium ions with the maximum adsorption capacity of 0.567 mg/g for Cr(VI) and 3.446 mg/g for Cr(III). Moreover, SPR reveals higher adsorption capacity for Cr(III) than that for Cr(VI), which implies that SPR has more potential application for Cr(III)-containing wastewater treatment than that for Cr(VI)-containing wastewater treatment. Foundation item: Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of China; Project(2008SK2007) supported by the Key Program of Science and Technology of Hunan Province, China     

Selective leaching of chromium-containing slag by HCl

A batch of column experiments was carried out to investigate the change of Cr（Ⅵ） concentration leached out from chromium-containing slag with HCI as leaching agent, and to study influences of pH, ratio of solid mass to solution volume, flow velocity and temperature on Cr（Ⅵ） leaching. The optimal parameters were obtained for Cr（Ⅵ） leaching and a fitting model was established to describe the procedure of Cr（Ⅵ） leaching. The results show that Cr（Ⅵ） concentration in leachate increases with decreasing pH and increasing flow velocity and temperature. Moreover, Cr（Ⅵ） leaching percentage increases with increasing ratio of solid mass to solution volume. The optimal parameters for Cr（Ⅵ） selective leaching are as follows： pH=3.0, 1：5 of ratio of solid mass to solution volume, 180 mL/min of flow velocity and 40 ℃ of temperature. The procedure of Cr（Ⅵ） leaching fits well with the model： v= 1.87t^-0.54, indicating that the leaching rate of Cr（Ⅵ） declines in an exponential order of-0.54.     

Speciation of chromium in soil inoculated with Cr（Ⅵ）-reducing strain, Bacillus sp. XW-4

Cr(VI)-amended soil was inoculated with Cr(VI)-reducing strain, Bacillus sp. XW-4 and incubated at 28 °C in an incubator. Cr(VI) reduction, available Cr and Cr fraction in soils were studied. The results show that addition of Bacillus sp. XW-4 can promote Cr(VI) reduction, but inoculation of this strain has a negative effect on the decrease of available Cr content in soil. In controls (without this strain) amended with 100 and 200 mg/kg of Cr(VI), Cr(VI) contents decrease to about 41 and 92 mg/kg respectively after incubation of 4 d, while in soil inoculated with XW-4, Cr(VI) contents decrease to about 18 and 60 mg/kg, respectively. The content of available Cr in soils with inoculation of XW-4 is higher than that in controls. Chromium is partitioned into water soluble Cr, exchangeable Cr, precipitated Cr, Cr bound to organics and residual Cr. The highest content of Cr is observed in residual form and water soluble Cr is not detected for all treatments after 42 d, but the soils inoculated with Bacillus sp. XW-4 contain higher content of exchangeable Cr and lower content of precipitated Cr than the soil without the inoculum. Inoculation of Bacillus sp. XW-4 can increase chromium activity in soils. Foundation item: Project(20050532009) supported by the Doctoral Foundation of Ministry of Education of China; Project supported by Program for Changjiang Scholars and Innovative Research Team in University     

Adsorption of copper（ Ⅱ ） and chromium（Ⅵ） on diaspore

The adsorption of Cu（ Ⅱ ） and Cr（Ⅵ） on diaspore was studied with the help of X-ray diffraction analysis, BET measurement, zeta potential measurement and atomic adsorption spectrometry. The adsorption equilibrium almost reaches within 60 min. The adsorption isotherms of Cu（ Ⅱ ） and Cr（Ⅵ） could be well described by the Langmuir equation. The adsorption capacities of Cu（Ⅱ） and Cr（Ⅵ） are 1.944 and 1.292 mg/g, respectively. The adsorption percentage of Cr（Ⅱ ） increases with the increment of solution pH, but the adsorption percentage of Cr（Ⅵ） decreases. This could be explained by zeta potential theoretical and electrostatic attraction between metal ions and diaspore surface.     

Removal of anionic ions from single material solution by bauxite tailings modified with FeCl3·6H2O

The adsorbabilities of the unmodified and modified bauxite tailings for Cr（Ⅵ）, As（Ⅴ） and F（Ⅰ） ions were investigated. Batch experiments were carried out to determine the removal rate as a function of adsorbent dosage, solution pH value and shaking time. The results show that the maximum removal rates of Cr（Ⅵ）, As（Ⅴ） and F（Ⅰ ） are respectively 99%, 99% and 90% by using the modified bauxite tailings. The isoelectric point of the unmodified bauxite tailings is 3.6, and that of the modified bauxite tailings is 5.0, which shifts to lower pH values in Cr（Ⅵ） solution. This indicates a specific adsorption of the anionic species on the modified bauxite railings. A new band of Cr2O72 appears in the FTIR, showing that Cr（Ⅵ） is adsorbed on the modified bauxite railings in the form of chemistry adsorption. The adsorption data of Cr（Ⅵ） on the modified bauxite tailings are well described by Freundlich model. The investigations of kinetic models show that pseudo-second-order kinetic model provides the best correlation for the experimental data.     

Disruption of bacterial cells by photocatalysis of montmorillonite supported titanium dioxide

The photo-induced antibacterial capacity of montmorillonite supported titanium dioxide (TiO₂/Mmt for short) was evaluated by using Escherichia coli and Staphylococcus aureus as modal organisms. The bactericidal activity of TiO₂/Mmt was examined by cell viability assay under different illumination modes. Atomic force microscopy (AFM) and total organic carbon/Total nitrogen (TOC/TN) analyses were employed to investigate the mechanism of the photocatalytic bactericidal process qualitatively and quantitatively. The kinetic data show that TiO₂/Mmt has excellent antibacterial performance, and about 99% of both bacteria cells are inactivated within 75 min illumination. The AFM images demonstrate that the bacterial cells are irreversibly decomposed and some cell components are dissolved. Therefore, the content and phase of carbon and nitrogen in the solution are changed after photocatalytic reaction. Funded by the National “973” Program of MOST of China (No. 2004CB619204), and the Scientific and Technological Research Key Project, Ministry of Education of China (No. 02052), the National High Tech. “863” Program of China (No. 2007AA06Z100), and the Scientific and Technological Research Key Project (No. 2007AA06Z123 )     

Adsorption and desorption properties of D318 resin for Cr（Ⅵ）

The adsorption capability of D318 resin for Cr(VI) was investigated by chemistry analysis. Experimental results show that D318 resin has the best adsorption ability for Cr(VI) at pH=3.16 in HAc-NaAc medium. The statically saturated adsorption capacity of the resin is 265.4 mg/g. The thermodynamic adsorption parameters, enthalpy change ΔH and free energy change ΔG ₂₉₈ of the adsorption reaction are 4.81 and −5.16 kJ/mol, respectively. The apparent activation energy E _a is 22.4 kJ/mol. The adsorption behavior obeys the Freundlich isotherm. The molar coordination ratio of the functional group of resin to Cr(VI) is 3:2. Cr(VI) adsorbed on D318 resin can be eluted by 5%NaOH-5%NaCl quantitatively. Foundation item: Project (Y304121) supported by the Natural Science Foundation of Zhejiang Province, China     

Stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling

The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent. Foundation item: Project(2007CB707706) supported by the Major State Basic Research Development Program of China; Projects(2007E213, 2007E203) supported by the Natural Science Foundation of Shaanxi Province, China     

Residual stresses within sprayed coatings

Some important developments of residual stress researches for coating-based systems were studied. The following topics were included the sources of residual stresses in coatings: error analysis of Stoney’s equation in the curvature method used for the measurement of coating residual stress, the modeling of residual stress and some analytical models for predicting the residual stresses in coatings. These topics should provide some important insights for the fail-safe design of the coating-based systems. Foundation item: Project(50235030) supported by the National Natural Science Foundation of China; Project(2003AA331130) supported by the National High-Tech Research and Development Program of China     

Fluorescence spectroscopy characteristics of humic acid by inoculating white-rot fungus during different phases of agricultural waste composting

The white-rot fungus, Phanerochaete chrysosporium (P. chrysosporium), was inoculated during different phases of agricultural waste composting, and its effect on the fluorescence spectroscopy characteristics of humic acid (HA) was studied. The results show that the emission spectra have a sharp peak at 400 nm and a broad shoulder with the maximum centered at 460 nm. The excitation spectra have two peaks and exhibit red shift (shift to longer wavelengths) at 470 nm. The synchronous scan spectra present a number of peaks and shoulders, and the peaks at shorter wavelengths disappear gradually and form a shoulder. At the final stage of composting, the fluorescence spectra have similar shapes, but the fluorescence intensities decrease. P. chrysosporium increases the degree of aromatization and polymerization of HA when it is inoculated during the second fermentation phase, while it does not produce an obvious change on the humification degree of HA when it is inoculated during the first fermentation phase. Compared with the fluorescence spectroscopy characteristics of HA from soil, the structure of HA from compost is simpler and the activity is higher. Foundation item: Project(2005CB724203) supported by the Major State Basic Research and Development Program of China; Project(IRT0719) supported by the Program for Changjiang Scholars and Innovative Research Team in University of China; Projects(50608029, 50808073) supported by the National Natural Science Foundation of China; Project(2007185) supported by the Environmental Protection Technology Research Program of Hunan Province, China