光合菌群利用丁酸产氢的初步研究

对影响光合茵群利用丁酸产氢的主要因子:初始细胞浓度、温度、初始pH值、光照强度和丁酸浓度进行了研究.结果表明,光合茵群在初始细胞浓度0.2～O.3 g/L,温度30~40℃,PH 6.0～9.0,光照强度2000～8000 Lx,丁酸浓度6～30 mmol/L的范围内均可以保持较高的产氢效率.当初始细胞浓度为0.3 g/L、温度30℃、初始PH 7.0、光照强度为4000 Lx、丁酸浓度为30 mmol/L时该光合茵群具有最大产氢量364 mL,最大产氢效率5.4 mol-H_2/mol-丁酸和最大产氢速率22.2 mL/L/h.     

十六烷基三甲基溴化铵强化产氢发酵

微生物发酵产生的生物气要经过细胞膜释放出去,产氢菌胞外膜的通透性影响产氢发酵过程。本文研究了十六烷基三甲基溴化铵(CTAB)对混合菌胞外膜通透性和厌氧产氢发酵过程的影响。研究结果表明:浓度大于0.009 5 g/L的CTAB可有效提高混合菌胞外膜的通透性;浓度小于0.045 0 g/L时,CTAB对发酵终端的生物量和pH无明显影响;在0.009 5⁰.027 0 g/L的CTAB条件下,发酵体系的产氢速率和累计产氢量随着CTAB浓度的增加而增加;在0.027 0 g/L的CTAB条件下,获得最大产氢速率19.6 mL/h和最大产氢效率13.6 mmol每克木糖,分别较未添加CTAB时提高44%和38%;在0.045 0 g/L的CTAB条件下,混合菌产氢能力受到明显抑制。这些研究结果表明:合适浓度的CTAB可以作为一种高效的生物活化剂用于强化厌氧产氢发酵。     

利用克雷伯氏菌进行同步糖化发酵产氢的研究

氢作为一种清洁的能源引起了人们的普遍重视.实验以产酸克雷伯氏菌(Klebsiella oxytoca)HP1为产氢菌株,以稻草粉为产氢底物,进行同步糖化发酵(Simultaneous Saccharification and Fermentation,SSF)产氢.对影响同步糖化发酵产氢的单因子进行试验,选取对氢产率影响较大的因子:温度、pH、纤维素酶用量等进行L9(34)正交试验.结果表明同步糖化发酵产氢的最佳条件为:温度40℃,pH6.5,纤维素酶用量为20FPAU/g稻草粉,摇床转速100r/min,发酵时间42h.在该条件下的最大氢产率为110.6mL/g稻草粉,稻草粉的氢转化率为22%.进行了10L放大发酵产氢试验,最大氢产率为122.3mL/g稻草粉,氢转化率为24.3%.与分步糖化发酵(Separate Hydrolysis and Fermentation,SHF)产氢相比,氢产率提高34.4%.研究表明,利用同步糖化发酵工艺可以提高生物制氢的产量和得率.     

厌氧活性污泥发酵制氢系统中的同型产乙酸菌及耗氢作用

 在对连续流搅拌槽式反应器(CSTR)发酵产氢系统中的活性污泥进行分子生物学分析,判断系统中有同型产乙酸菌存在的基础上,通过活性污泥的间歇培养试验,探讨了同型产乙酸作用对活性污泥发酵系统产氢效能的影响.结果表明,CSTR发酵产氢系统的活性污泥中,一种隶属真杆菌属(Eubacterium)的同型产乙酸菌在活性污泥微生物群落中达到了优势程度;以葡萄糖为底物时,同型产乙酸菌的耗氢代谢,可使厌氧活性污泥对葡萄糖的氢气转化率及产氢率分别降低31%和34%,耗氢速率可达0.33mmol/(g·d).     

克雷伯菌HQ-3厌氧发酵产氢培养基的优化

运用Plackett-Burman设计实验结合SAS数据分析对基于克雷伯菌HQ-3(Klebsiellasp.HQ-3)产氢培养基的主效因素进行筛选,确定产氢培养基的主效因素,利用最陡爬坡实验确定主效因素的响应面中心值,用响应面法和Matlab7.0对厌氧发酵的产氢培养基的主效因子进行了优化.得到的优化的产氢培养基(YH培养基)为:Na2HPO4.12H2O,15.0g/L;KH2PO4,7.7g/L;MgSO4.7H2O,3.7g/L;葡萄糖,21.4g/L;蛋白胨,18.1g/L;酵母膏,8.0g/L;pH=8.3.利用优化的培养基进行厌氧发酵产氢验证,得到最大产氢量为826.3mL/L,与预测值806.0mL/L基本相符.并且优化培养基较初始培养基产氢量621.2mL/L,提高了33%.在最优发酵条件下,对发酵液相产物乙醇、甲酸、乙酸、丙酸、正丁酸、异丁酸进行测定,发现乙醇、甲酸、乙酸含量占总液相产物的93%,确定其发酵类型为混合酸途径.     

霉菌菌丝球对重金属Cr(Ⅵ)的吸附特性

自活性污泥中筛选到一株对重金属Cr(VI)有很强吸附能力的霉菌菌株G-28。结果表明,G-28菌丝球吸附铬的适宜pH为1.0~3.0,适宜温度为20~45℃。在Cr(VI)初始浓度10~60 mg.L-1范围内,G-28对Cr(VI)吸附效果明显。该菌株吸附铬的适宜摇速为150~180 r.min-1,吸附率达98.2%~98.8%。培养48 h的菌丝球对Cr(VI)的吸附率最大。吸附动力学研究表明,G-28对铬的吸附0~2h是一个快速过程,而2~12 h为慢吸附过程,12 h后趋于平衡。G-28菌丝球灭活后,仍具有较强的吸附能力。G-28对电镀废水Cr(VI)的吸附率高达99.1%。     

混合培养系统厌氧发酵同步产氢产乙醇研究(英文)

采用连续流槽式搅拌反应系统(ACSTR)作为反应装置,以制糖废水为底物,污水处理厂剩余污泥为反应的启动污泥,着重研究底物质量浓度和HRT对系统同步产氢产乙醇性能的影响.结果表明,在不同的底物质量浓度和HRT条件下,乙醇产量和氢气产量有着相同的变化趋势.当底物质量浓度和HRT分别为6 g COD/L和6 h时,乙醇和氢气产量分别为1.62/7.25 mmol/(L·h)and 2.97/8.73 mmol/(L·h).线性分析发现乙醇产量和氢气产量之间有很好的相关性,线性方程分别为y=0.156 6x+0.4487(r2=0.8778)和y=0.148 8x+1.671 4(r2=0.9838).     

底物浓度对光合产氢过程动力学的影响

以光合产氢混合菌种为研究对象,采用实验研究和模型拟合的方法进行底物浓度对产氢过程动力学影响的研究.结果表明,底物浓度为5、10 mg/mL的产氢系统,底物消耗利用程度较高,20 mg/mL的系统存在未完全降解利用的物质,底物最大消耗利用量为17.014 6 mg/mL.各产氢系的统产氢速率分别在95、101、107 h达到最大,即底物浓度低,光合细菌对底物的消耗利用程度高,最大产氢速率出现较早. Gompertz模型拟合氢气生成的相关系数均大于99%,且氢气生成和底物消耗主要在混合菌种对数生长期和稳定期前期.     

同型产乙酸菌株CA3及其发酵葡萄糖产乙酸条件优化

 同型产乙酸菌纯培养物的获得,可为研究其在厌氧生物处理系统中的生理生态功能以及生产化工溶剂乙酸提供种质资源。以CO₂为碳源,采用改良Hungate厌氧技术,从厌氧活性污泥中分离得到一株同型产乙酸菌CA3。该菌株为严格厌氧,卵形,G⁺,可利用H₂/CO₂产乙酸,也能发酵葡萄糖、果糖等产生乙酸。16SrRNA基因序列比对及系统发育树构建结果表明,CA3隶属Blautia sp.。菌株CA3能在20~45℃的温度范围内生长,最适生长温度为35℃,最适初始pH值为8.0。在最适条件下,菌株CA3利用H₂/CO₂产乙酸速率可达8.92mg/(L·h);以酵母粉作为氮源发酵葡萄糖时,发酵体系的乙酸浓度可达1370mg/L。     

土曲霉M11液体发酵时菌丝球形态与发酵产酶的关系

在不同的培养条件(如接种量、初始pH、温度、转速、不同碳氮源等)下,对土曲霉M11菌丝球的形态与产酶量的关系进行了深入研究,可以观察到有3种基本的菌丝球形态:丝状体、团块和球形,并且大小与致密度有明显差异.结果表明,即使在不同培养条件下,大小一致、致密的球形菌丝球(直径1～2 mm)都具有最高的产酶量,菌丝球的形态与真菌产酶量密切相关.因此,在工业发酵产酶过程中,对菌丝球形态的检测,可以作为一种关键的指标来检测发酵的效果.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Features of Women''s language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme