厌氧产氢菌的分离筛选、诱变选育及其产氢特性的研究

本文从四川绵竹酒厂、成都市龙泉长安垃圾填埋场以及四川大学荷花池底的厌氧污泥中先后分离得到63株厌氧产氢菌，其中H-8、H-61、HC-10等16株产氢细菌产氢能力较高，HC-10的产氢能力最高，最大产氢量和最大产氢速率分别达到2840 ml H2/L培养基和25.39 mmol H2/g drycell·h，对HC-10进行生理生化鉴定和分子生物学鉴定，判定其为clostridium sp.，对HC-10的产氢条件进行了研究，结果表明，该菌的最适生长温度为35 ℃，最适生长初始pH为7，以葡萄糖为最佳碳源，以蛋白胨为最佳氮源，不利用无机氮源，其产氢发酵液相产物以乙醇和乙酸为主，其发酵类型属于乙醇型发酵。此外，以酒糟废液作为底物，进行了菌株HC-10的生物强化试验，研究表明，投加了HC-10的强化系统其产氢量比对照高出40.32%。 同时为了获得厌氧产氢菌的高效突变株，分别以产氢菌H-8和H-61为原始菌株进行微波诱变处理，对微波诱变参数进行了优化，考察了突变株的遗传稳定性、产氢特性及耐酸性。菌株H-8经过微波诱变得到5株高产氢突变株HW7、HW33、HW181、HW184、HW195，经多次传代表明HW195是稳定的高产突变株。突变株HW195具有较好的耐酸性，在pH值为2.8时仍能生长。通过间歇发酵实验，其最大产氢量和最大产氢速率分别达到2460 mL/L培养基和27.97 mmol H2/g drycell·h，比原始菌分别提高了50.75%和41.7%。菌株H-61经过微波诱变后选育得到的突变株HW-18，其最大产氢量和最大产氢速率分别达到2190 mL/L培养基和25.86 mmol H2/g drycell·h，比原始菌分别提高了23.03%和31.00%。 为了对比各种诱变方式对产氢菌产氢能力的影响，以厌氧产氢菌H-61为原始菌株，先后经亚硝基胍(NTG)、紫外(UV)诱变，选育得到1株高产突变株HCM-23。在葡萄糖浓度为10 g/L的条件下，其产氢量为3024 mL/L培养基，比原始菌株提高了69.89%；其最大产氢速率为33.19 mmol H2/g drycell·h，比原始菌株提高了68.14%。经过多次传代实验，稳定性良好。其发酵末端产物以乙醇和乙酸为主，属于典型乙醇型发酵。其最适产氢初始pH为6.5，最适生长温度为36 ℃，以蔗糖为最佳碳源。与原始菌株相比，突变株HCM-23的产氢特性发生了改变，如生长延滞期延长，可利用无机氮源等。 From anaerobic activated sludge, 16 strains of hydrogen producing bacteria were newly isolated. One of them named as HC-10 had the highest hydrogen producing capability, under the batch fermentative hydrogen production condition, the maximal hydrogen yield and hydrogen production rate was 2840 mL/L culture and 25.39 mmol H2/g drycell·h. It was identified as clostridium sp.HC-10 by 16S rDNA sequence analysis. Various parameters for hydrogen production, including substrates, initial pH and temperature, have been studied. The optimum condition for hydrogen producing of strain HC-10 were achieved as: initial pH 7.0, temperature 35 ℃, glucose as the favorite substrate, Moreover, using distiller's solubles wastewater as substrate, HC-10 strain was added in the biohydrogen producing system to research the bioaugmentation effection. The results showed that the hydrogen production of bioaugmentation system was 40.32% higher than the noaugmentation system. An anaerobic, hydrogen producing strain H-8 was irradiated by microwave to optimize the microwave mutagenesis condition, and to test the heredity, hydrogen-producing potential and aciduric of the mutants. An aciduric mutant named as HW195 with steady hydrogen-producing capability was obtained, which can grow at pH 2.8. Its capability of hydrogen production was tested in the batch culture experiments. The maximum hydrogen yield and hydrogen production rate was 2460 mL/L culture and 29.97 mmol H2/g drycell·h, which was 50.7% and 41.7% higher than those of the initial strain, respectively. When used the strain H-61 as original strain, a mutant named as HW18 was obtained. The maximum hydrogen yield and hydrogen production rate was 2190 mL/L culture and 25.86 mmol H2/g drycell·h, which was 23.03% and 31.00% higher than those of the initial strain, respectively. The results demonstrated that microwave mutagenesis could be used in the field of hydrogen producing microorganism. The hydrogen producing strain H-61 was used as an original strain which was induced by NTG and UV for increasing and the hydrogen production capability. One of the highest efficient H2-producing mutants was named as HCM-23 with its stable hydrogen production capability. which was tested in the batch culture experiments. With the condition of 10 g/L glucose, its cumulative hydrogen yield and hydrogen production rate was 3024 mL/L culture and 33.19 mmol H2/g drycell·h, 69.89％and 68.14％ higher than that of the original strain, respectively. The terminal liquid product compositions showed that the mutant HCM-23 fermentation was ethanol type, while the original strain H-61 fermentation was butyric acid type. Varieties of parameters of hydrogen production fermentation were studied, including time, carbon source, nitrogen source, glucose concentration, glucose utilization, initial pH and incubation temperature had been studied, indicated the optimum condition of hydrogen production for the mutant HCM-23 as initial pH6.5, temperature 36 ℃, and the favorite substrate was sucrose. The hydrogen production characters of the mutant and the original strain were different, such as, the growth lag phase and the utilization of inorganic nitrogen source, etc. This work shows a good application potential of NTG-UV combined mutation in the biohydrogen production. And the hydrogen production mechanism and metabolic pathway should be explored furthermore.

不同森林管理预案下友好林业局森林景观的动态变化

Knowledge about cumulative effects of forest management alternatives on forest landscape is required to make forest management decision. In this paper,a spatially explicit landscape model,LANDIS,was applied to simulate forest landscape changes in 200 years under four management alternatives (no cutting,clearcutting,selective cutting I and II) in Youhao Forestry Bureau located in Small Khingan Mountains. APACK was used to calculate distribution area of the representative species and species age cohort for six species. The results showed:1) timber harvest decreased area percentage of representative conifer species,Pinus koraiensis,Picea koraiensis and Picea jezoensis,Larix gmelinii to some extent compared to no cutting. The most influencing cutting mode for the area percentage of Tilia amurensis and Quercus mongolica was selective cutting II,followed by selective cutting I and clearcutting. To the contrast,the change of area percentage of Betula phatyphylla was contrary to the management alternatives; 2) As to species age cohort composition,timber harvest significantly changed age structure,that is,it decreased over-matured age cohort of representative species,and increased seedling and middle-age cohort (B. phatyphylla was not included,because its area percentage of over-mature age cohort was the highest under clearcutting than other three scenarios).

Synthesis and spectroscopic study of mesoporous aluminum methylphosphonate foam templated by dibutyl methylphosphonate

New types of templates and novel interactive mechanisms between template and framework are very important for creating porous materials. In this work, by using neutral dibutyl methylphosphonate as a template, an inorganic-organic hybrid mesoporous material, aluminum methylphosphonate, was prepared. The as-synthesized material was studied by P-31 magnetic angle spinning nuclear magnetic resonance (MAS NMR), Al-27 MAS NMR, C-13 CP/MAS, FT-IR spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), and transmission electron microscopy. After thermal treatment at 673 K and 10 mmHg for 2 h, hybrid mesoporous foam was obtained. The transformation process was investigated by FT-IR. TG-DTA results indicate that the methyl group bonded to the framework keeps intact up to 792 K under air and 823 K under nitrogen. The characterization results from nitrogen gas adsorption-desorption measurements show that the BET surface area and the Barrett-Joyner-Halenda desorption cumulative pore volume of the foam are 90 m(2) g(-1) and 0.32 cm(3) g(-1) respectively. (C) 2003 Elsevier Inc. All rights reserved.

Measures for describing the size distribution of sediments

Numerous measures are used in the literature to describe the grain-size distribution of sediments. Consideration of these measures indicates that parameters computed from quartiles may not be as significant as those based on more rigorous statistical concepts. In addition, the lack of standardization of descriptive measures has resulted in limited application of the findings from one locality to another. The use of five parameters that serve as approximate graphic analogies to the moment measures commonly employed in statistics is recommended. The parameters are computed from five percentile diameters obtained from the cumulative size-frequency curve of a sediment. They include the mean (or median) diameter, standard deviation, kurtosis, and two measures of skewness, the second measure being sensitive to skew properties of the "tails" of the sediment distribution. If the five descriptive measures are listed for a sediment, it is possible to compute the five percentile diameters on which they are based (phi 5 , phi 16 , phi 50 , phi 84 , and phi 95 ), and hence five significant points on the cumulative carve of the sediment. This increases the value of the data listed for a sediment in a report, and in many cases eliminates the necessity of including the complete mechanical analysis of the sediment. The degree of correlation of the graphic parameters to the corresponding moment measures decreases as the distribution becomes more skew. However, for a fairly wide range of distributions, the first three moment measures can be ascertained from the graphic parameters with about the same degree of accuracy as is obtained by computing rough moment measures.

不同碎石含量及直径对土壤水分入渗过程的影响

Cumulative infiltration; Wetting front; Content of rock fragments; Size of rock fragments; 【摘要】 由于成土原因或人类活动,一些土壤中含有不同含量及大小的碎石。碎石的存在改变了土壤的某些物理特性,入渗过程也因此受到影响。本研究采用定水头入渗试验装置,对7种不同碎石含量(0%,10%,20%,30%,40%,50%,60%)及4种不同碎石直径(0.2~0.5cm,0.5~1.0 cm,1.0~3.0 cm,3.0~4.0 cm)的土壤水分入渗过程进行室内研究,旨在分析碎石含量及直径对土壤入渗过程的影响及其原因,为土石混合介质的研究提供一些理论基础。

盘式吸渗仪吸渗率计算方法比较

选用盘径为5 cm和15 cm的盘式吸渗仪,对杨凌土(粘土)和神木砂黄土(砂壤土)两种质地的土壤在0、-3、-6、-9-、12 cm水头5种负压下进行了室内吸渗实验,分析了不同盘径和负压对累积吸渗量的影响;并选用4种吸渗率公式对这两种质地土壤吸渗率进行了计算,以Vandervaere法为参考方法对该4种方法的适用性进行了分析。结果表明,在相同的时间内,两种土壤5 cm盘径下的累积吸渗量均大于15 cm盘径下的累积吸渗量,砂黄土累积吸渗量大于相同负压下土累积吸渗量;在4种吸渗率计算方法中,无论土还是砂黄土,Haverkamp公式所得吸渗率值与参考方法最接近。

可溶性有机氮在评价土壤供氮能力中的作用与效果

淹水培养法提取态可溶性有机氮在评价土壤供氮能力方面具有重要意义。【方法】通过研究黄土高原物理化学性质差异较大的10种农田土样起始可溶性有机氮(SON)、矿质氮(Nmin)及间歇浸提长期淹水培养期间可溶性有机氮、铵态氮累积量、易矿化和难矿化氮素矿化势(分别ND和NR表示)及其与作物吸氮量的关系,分析SON在评价土壤供氮能力中的作用与效果。【结果】供试土样起始SON平均为23.9mg·kg-1,是起始可溶性总氮的28.8%、全氮的2.4%。淹水培养提取态可溶性氮(TSN)中,SON所占比例更高,几乎与铵态氮相当。经过217d淹水培养,浸提出的SON平均为118.1mg·kg-1,占TSN累积量的46.4%。ND与全氮关系密切:在不包括与包括SON时,二者的相关系数分别为0.92(P<0.01)和0.88(P<0.01)。不同土壤ND和易矿化氮矿化速率(KD)差别很大,干湿砂质新成土和黄土正常新成土的ND小于土垫旱耕人为土。考虑SON后KD值减小,而难矿化氮矿化速率(KR)增加。【结论】淹水培养期间铵态氮累积量是评价可矿化氮的较好指标,不仅适宜于第一季作物,而且也适用于连续两季作物;SON累积量不能单独作为...

塿土坡面降雨水沙运移实验研究

黄土高原是我国植被破坏与水土流失最为严重的地区。本文基于室内坡地降雨实验,分析了塿土坡面降雨入渗补给系数的变化,对比了不同雨强影响下径流泥沙含量和累积泥沙含量的时间变化趋势,并将侵蚀与入渗结合,分析了同时段产沙量和入渗率的变化关系,研究表明:入渗补给系数随雨强增大而逐渐减小,两者可描述为线性关系,雨强越小,入渗补给系数越高;降雨初始产沙值最大,在产沙10 min内变缓。雨强大的,初始产沙量和稳定沙量都稍大,但总体差异不大,产沙量分布曲线形状与入渗率曲线极为相似;不同雨强下累积泥沙量与降雨历时之间存在明显的幂函数关系,且幂函数的指数部分基本随降雨雨强增加而逐渐增加;不同雨强下入渗率和累积泥沙量的变化趋势相反,当累积泥沙量增加,相应的土壤入渗率减小,两者变化趋势随雨强增大而趋于明显。

Effects of nitrogen fertilization on soil respiration in temperate grassland in Inner Mongolia, China

Nitrogen addition to soil can play a vital role in influencing the losses of soil carbon by respiration in N-deficient terrestrial ecosystems. The aim of this study was to clarify the effects of different levels of nitrogen fertilization (HN, 200 kg N ha(-1) year(-1); MN, 100 kg N ha(-1) year(-1); LN, 50 kg N ha(-1) year(-1)) on soil respiration compared with non-fertilization (CK, 0 kg N ha(-1) year(-1)), from July 2007 to September 2008, in temperate grassland in Inner Mongolia, China. Results showed that N fertilization did not change the seasonal patterns of soil respiration, which were mainly controlled by soil heat-water conditions. However, N fertilization could change the relationships between soil respiration and soil temperature, and water regimes. Soil respiration dependence on soil moisture was increased by N fertilization, and the soil temperature sensitivity was similar in the treatments of HN, LN, and CK treatments (Q (10) varied within 1.70-1.74) but was slightly reduced in MN treatment (Q (10) = 1.63). N fertilization increased soil CO2 emission in the order MN > HN > LN compared with the CK treatment. The positive effects reached a significant level for HN and MN (P < 0.05) and reached a marginally significant level for LN (P = 0.059 < 0.1) based on the cumulative soil respiration during the 2007 growing season after fertilization (July-September 2007). Furthermore, the differences between the three fertilization treatments and CK reached the very significant level of 0.01 on the basis of the data during the first entire year after fertilization (July 2007-June 2008). The annual total soil respiration was 53, 57, and 24% higher than in the CK plots (465 g m(-2) year(-1)). However, the positive effects did not reach the significant level for any treatment in the 2008 growing season after the second year fertilization (July-September 2008, P > 0.05). The pairwise differences between the three N-level treatments were not significant in either year (P > 0.05).

Knocking-Down Cyclin A(2) by siRNA Suppresses Apoptosis and Switches Differentiation Pathways in K562 Cells upon Administration with Doxorubicin

Cyclin A(2) is critical for the initiation of DNA replication, transcription and cell cycle regulation. Cumulative evidences indicate that the deregulation of cyclin A(2) is tightly linked to the chromosomal instability, neoplastic transformation and tumor proliferation. Here we report that treatment of chronic myelogenous leukaemia K562 cells with doxorubicin results in an accumulation of cyclin A(2) and follows by induction of apoptotic cell death. To investigate the potential preclinical relevance, K562 cells were transiently transfected with the siRNA targeting cyclin A(2) by functionalized single wall carbon nanotubes. Knocking down the expression of cyclin A(2) in K562 cells suppressed doxorubicin-induced growth arrest and cell apoptosis. Upon administration with doxorubicin, K562 cells with reduced cyclin A(2) showed a significant decrease in erythroid differentiation, and a small fraction of cells were differentiated along megakaryocytic and monocyte-macrophage pathways. The results demonstrate the pro-apoptotic role of cyclin A(2) and suggest that cyclin A(2) is a key regulator of cell differentiation.

Luminescence functionalization of SBA-15 by YVO4 : Eu3+ as a novel drug delivery system

Luminescence functionalization of the ordered mesoporous SBA-15 silica was realized by depositing a YVO4:Eu3+ phosphor layer on its surface via the Pechini sol-gel process, resulting in the formation of the YVO4:Eu3+@SBA-15 composite material. This material, which combines the mesoporous structure of SBA-15 and the strong red luminescence property of YVO4:Eu3+, can be used as a novel functional drug delivery system. The structure, morphology, porosity, and optical properties of the materials were well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, N-2 adsorption, and photoluminescence spectra. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the YVO4:Eu3+ layer and the adsorption of ibuprofen (IBU, drug). The IBU-loaded YVO4:Eu3+@SBA-15 system still shows the red emission of Eu3+ (617 nm, D-5(0)-F-7(2)) under UV irradiation and the controlled drug release property. Additionally, the emission intensity of Eu3+ increases with an increase in the cumulative released amount of IBU in the system, making the extent of drug release easily identifiable, trackable, and monitorable by the change of luminescence. The system has great potential in the drug delivery and disease therapy fields.

MCM-41 functionalized with YVO4 : Eu3+: a novel drug delivery system

Luminescence functionalization of ordered mesoporous MCM-41 silica was realized by depositing a YVO4:Eu3+ phosphor layer on its surface via the Pechini sol-gel process. This material, which combines the mesoporous structure of MCM-41 and the strong red luminescence property of YVO4: Eu3+, has been studied as a host carrier for drug delivery/release systems. The structure, morphology, texture and optical properties of the materials were well characterized by x-ray diffraction ( XRD), Fourier infrared spectroscopy ( FT-IR), transmission electron microscopy ( TEM), N-2 adsorption and photoluminescence ( PL) spectra. The results indicated that the specific surface area and pore volume of MCM-41, which were directly correlated to the drug-loading amount and ibuprofen ( IBU) release rate, decreased in sequence after deposition of YVO4:Eu3+ and loading of IBU as expected. The IBU-loaded YVO4:Eu3+@ MCM-41 system still showed red luminescence under UV irradiation ( 365 nm) and a controlled release property for IBU. In addition, the emission intensity of Eu3+ increases with an increase in the cumulative released amount of IBU, making the extent of drug release easily identified, tracked and monitored by the change of luminescence, which demonstrates its potential application in drug delivery/release systems.

Characterization of the microstructure of biaxially oriented polypropylene using preparative temperature-rising elution fractionation

Two commercial biaxially oriented polypropylene (BOPP) resins, resin A and resin B, having different processing properties, were fractionated by preparative temperature-rising elution fractionation (TREF). The TREF fractions were further characterized by gel permeation chromatography (GPC), gel permeation chromatography coupled with light scattering (GPC-LS), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). GPC-LS did not find visible long-chain branching in either resin A or B. The results from TREF and DSC indicate that the fractional melting parameter f(T) may be used to predict the profile of the TREF cumulative weight distribution curve. GPC results show that the molecular weights of the fractions tend to increase with elution temperature. WAXD and DSC data show that the crystallinity of fractions does not increase monotonically with increase of elution temperature. There appears to be a maximum in the plot of crystallinity versus elution temperature. The high-speed BOPP resin A has a lower isotacticity but a homogeneous isotacticity distribution and a higher molecular weight but a broader molecular weight distribution than resin B.

Production of active oxygen species from Taxus cuspidata induced by far-UV radiation

In order to understand the role of active oxygen species in mediating plant injuries induced by far-UV radiation, seedlings of Taxus cuspidata Sieb. et Zucc. were irradiated by far-UV rays in laboratory for 4 weeks. The production of organic free-radicals in detached needles, and the production of O-2(radical anion) and O-1(2) in isolated chloroplasts were detected weekly by electron spin resonance (ESR) to evaluate their relative importance. The results show that the cumulative effect of far-UV irradiation, is best indicated by the production of organic free radicals in the needles, O-2(radical anion) production in chloroplasts is the next. The enhancement of O-1(2) production in chloroplasts by the cumulative far-UV irradiation seems to be not so important as O-2(radical anion) in mediating injuries induced by, far-UV radiation because of its high background value.