生物质制氢技术研究进展

氢能以其清洁,来源广泛及用途广等优点成为最有希望的替代能源之一,用可再生能源制氢是氢能发展的必然趋势。由于生物质制氢具有一系列独特的优点,它已成为发展氢经济颇具前景的研究领域之一。生物质制氢技术可以分为两类,一类是以生物质为原料利用热物理化学方法制取氢气,如生物质气化制氢,超临界转化制氢,高温分解制氢等热化学发制氢,以及基于生物质的甲烷、甲醇、乙醇的化学重整转化制氢等;另一类是利用生物转化途径转换制氢,包括直接生物光解,间接生物光解,光发酵,光合异养细菌水气转移反应合成氢气,暗发酵和微生物燃料电池等技术。本文综述了目前主要的生物质制氢技术及其发展概况,并分析了各技术的发展趋势。     

国际生物制氢相关研究的知识图谱分析

氢气是一种理想的洁净能源。生物制氢技术具有能耗低、环保等优势,是目前国内外研究的热点。从能源和环境角度考虑,发展生物制氢技术都具有重要的意义。通过ISI Web of Knowledge网络数据库检索2000~2008年8月期间生物制氢的相关研究,利用作者共引分析方法,并绘制了知识图谱。该图谱显示出此研究领域存在两大主流学术群体：群体1,其研究焦点为光解水制氢两大类,包括藻类光合制氢和蓝细菌等光合细胞制氢;群体2,其研究聚集在厌氧发酵制氢研究方面,又分为暗发酵制氢和光发酵制氢。其中厌氧发酵制氢的研究人员比较密集,说明这方面的研究是目前该领域的重点。     

生物制氢技术的研究进展

氢是一种理想的清洁能源 ,生物制氢在新能源的研究利用中占有日趋重要的位置。目前采用的生物制氢技术成本较高 ,使用价格低廉、来源丰富的原料是降低其成本的一条重要途径 ,利用生物质 ,尤其是纤维素类物质制氢是新的发展方向。综述了与微生物制氢有关的酶的作用机制 ,相关菌类的产氢机理及研究进展。     

生物质合成气催化制取甲烷研究进展

天然气的供需矛盾促使人们去寻找新的天然气资源,其中利用生物质热化学催化制取生物质基天然气的技术受到了全世界的广泛关注。而生物质合成气催化制取甲烷是该工艺流程的核心步骤之一。分别从甲烷化反应器和甲烷化催化剂两个方面阐述了国际上生物质合成气催化制取甲烷的研究现状,并综述了关于甲烷化催化剂积碳现象的研究进展。同时分析了目前生物质合成气催化制取甲烷面临的主要问题,并指明了未来的发展方向。     

生物质催化转化制备呋喃基化学品和酚类化合物

生物质转化制备精细化学品是解决石油能源危机的重要途径之一。其中,纤维素及半纤维素转化合成呋喃基化学品与木质素转化制酚类化合物是主要的反应路线,特别是借助催化技术加速生物质转化更是当今化学领域的研究重点;依据催化反应体系的不同,对近年来用于生物质催化转化的反应媒介以及催化剂研究进展进行了综述,并对未来生物质催化转化研究方向的发展前景进行了展望。     

微藻光生物水解制氢技术

氢气是未来人类社会可持续发展的理想能源。介绍微藻太阳能光生物水解制氢的研究现状,重点讨论微藻光水解制氢的生物学原理。重点讨论微藻光解水制氢的酶学机理、工艺过程以及当前的主要研究方向。通过比较微藻固氮酶制氢、可逆产氢酶直接光水解制氢、可逆产氢酶间接光水解制氢等技术路线的优缺点,指出利用微藻可逆产氢酶两步法间接光水解制氢最具发展潜力,可望为21世纪的“氢能经济社会”提供大量的氢源。该技术成功的关键在于相关的基因工程和代谢调控研究取得重大突破。     

联合生物制氢方法及发展趋势

为了在生物制氢过程中最大限度提高产氢量和产氢速率,增大底物的利用率以及更好地发挥菌种间的协同作用,联合生物制氢技术成为近年来人们关注的焦点。综述了目前国内外几种联合生物制氢方法的研究现状。并从产氢机理的角度对几种联合制氢技术进行了分析比较,重点强调光合发酵和暗发酵联合生物制氢技术具有广泛的发展前景,并指出其存在的问题和未来的发展趋势。     

超临界甲醇酯交换法制备生物柴油研究进展

超临界甲醇法制备生物柴油是动、植物油脂与超临界甲醇发生酯交换反应生成脂肪酸甲酯的工艺。与传统的酸、碱催化法以及酶催化法等技术相比,超临界酯交换反应具有不需要催化剂、反应速度快、产物分离简单等突出特点。缺点在于反应温度和压力条件不够温和,对设备要求较高,操作费用可观。如何从系统工程的角度发挥其优点、克服缺点,则是未来该项技术能否实现工业化应用的关键。回顾了该技术的研究进展,重点对过程的影响因素进行了分析讨论。     

多级孔分子筛在生物质催化热裂解制备芳烃中的研究进展

芳烃是石化工业的一种重要基础原料,目前主要来源于石油和煤焦油。随着化石能源的日益枯竭、全球环境问题的日益严重和芳烃需求量的不断增长,芳烃的传统生产工艺压力越来越大。生物质催化热解制备芳烃技术由于其绿色、原料来源广以及可持续等优点,近年来备受关注。微孔分子筛因其大比表面积、强酸性、微孔择形性和良好的水热稳定性等优点成为理想的催化热解催化剂,但是微孔分子筛扩散阻力大、易积碳致使催化剂寿命低,使其在生物质催化热解制备芳烃的应用方面受到很大限制。在微孔分子筛中引入介孔得到多级孔分子筛,可以有效解决分子传质问题,并且保留微孔的强酸性以及择形选择,提高催化反应活性的同时提高催化剂的使用寿命,因此,多级孔分子筛成为了近年来生物质催化热解的热点。本文中,笔者详细综述了近年来生物质催化热裂解制备芳烃过程中所需要的原料和反应机制,重点综述了多级孔分子筛的优势以及其在生物质催化热解制备芳烃方面的应用前景和研究进展,最后总结了该技术面临的挑战和发展方向。     

固定化技术在促进光合细菌产氢中的应用

氢气是一种新型的清洁高效能源,制氢技术的创新是目前研究的热点。将新型的技术及材料应用到生物制氢工艺中,从而促进生物制氢技术的产氢效率和工程应用是研究的重点之一。该文阐述了光合细菌在固定化生长条件下发酵产氢的最新研究进展,从固定化技术的原理、固定化方法的应用进展及影响因素几个方面进行了综述,详细阐述了包括包埋、悬浮载体附着生长及固定生物膜法等几种固定化方法对光发酵产氢的作用,介绍了国内外用于固定化的新型材料,并对今后的研究重点及方向进行了展望。     

T lymphocyte-dependent evolution of bacterial cell wall-induced hepatic granulomas

Injection of streptococcal cell walls (SCW) i.p. into susceptible rats results in dissemination of SCW primarily to the liver, spleen, bone marrow, and peripheral joints. Within the liver, the SCW are phagocytized by the Kupffer cells, initiating a sequence of events leading to the formation of hepatic granulomas. The granulomas are characterized by large numbers of W3/13+, W3/25+ T lymphocytes and Ia+, esterase-positive macrophages. The generation of inflammatory mediators by these mononuclear cells appears to be central to the evolution of the granulomas and the subsequent fibrotic sequelae evoked by the SCW. In the absence of functional T lymphocytes (athymic rats), injection of SCW does not trigger lymphokine production, and organized granulomas do not develop in the livers. Furthermore, inhibition of T lymphocyte proliferation and lymphokine synthesis pharmacologically by cyclosporin A administration in euthymic animals inhibits SCW-induced hepatic granuloma development. Although macrophage function is apparently not impaired as evidenced by IL 1 and PGE2 production, a chronic inflammatory response to SCW cannot be sustained in the absence of T lymphocyte participation. These studies provide insight into the cellular and molecular mechanisms leading to formation and maintenance of chronic granulomatous lesions.     

The effects of miracidal aging and dilution of snail-conditioned water on responses of miracidia of Megalodiscus temperatus.

Miracidia of Megalodiscus temperatus from newly hatched until 10 hr old were tested for their ability to react to Helisoma trivolvis snail-conditioned water (SCW) by contact with return (CR) to agar blocks and by percentage of miracidia reacting to a point inoculation of SCW as determined by a photographic time exposure method. CR to agar blocks containing 1:50 SCW was greatest during the first 6 hr after hatching but declined thereafter. The reaction during the first hour to a point inoculation was lower than during the 2nd and 3rd hr. Results were variable from 4 to 10 hr after hatching with the lowest response recorded from 9 to 10 hr. Miracidial responses to dilutions of SCW were assessed by the same two methods. CR to agar blocks containing decreasing concentrations of SCW declined until at a dilution of 1:500 CR was only slightly above the controls. On the other hand, miracidial reactions to point inoculations of SCW as determined by the photographic method were still apparent at a dilution of 1:25,000, when 12% of the miracidia tested reacted. Thus, the photographic time exposure method gives a sensitive means for detecting altered miracidial behavior to various intrinsic and extrinsic factors.     

Consolidated bioprocessing performance of <Emphasis Type="Italic">Thermoanaerobacterium thermosaccharolyticum</Emphasis> M18 on fungal pretreated cornstalk for enhanced hydrogen production

Background

Biological hydrogen production from lignocellulosic biomass shows great potential as a promising alternative to conventional hydrogen production methods, such as electrolysis of water and coal gasification. Currently, most researches on biohydrogen production from lignocellulose concentrate on consolidated bioprocessing, which has the advantages of simpler operation and lower cost over processes featuring dedicated cellulase production. However, the recalcitrance of the lignin structure induces a low cellulase activity, making the carbohydrates in the hetero-matrix more unapproachable. Pretreatment of lignocellulosic biomass is consequently an extremely important step in the commercialization of biohydrogen, and for massive realization of lignocellulosic biomass as alternative fuel feedstock. Thus, development of a pretreatment method which is cost efficient, environmentally benign, and highly efficient for enhanced consolidated bioprocessing of lignocellulosic biomass to hydrogen is essential.

Results

In this research, fungal pretreatment was adopted for enhanced hydrogen production by consolidated bioprocessing performance. To confirm the fungal pretreatment efficiency, two typical thermochemical pretreatments were also compared side by side. Results showed that the fungal pretreatment was superior to the other pretreatments in terms of high lignin reduction of up to 35.3% with least holocellulose loss (the value was only 9.5%). Microscopic structure observation combined with Fourier transform infrared spectroscopy (FTIR) analysis further demonstrated that the lignin and crystallinity of lignocellulose were decreased with better holocellulose reservation. Upon fungal pretreatment, the hydrogen yield and hydrogen production rate were 6.8 mmol H₂ g^-1 pretreated substrate and 0.89 mmol L^-1 h^-1, respectively, which were 2.9 and 4 times higher than the values obtained for the untreated sample.

Conclusions

Results revealed that although all pretreatments could contribute to the enhancement of hydrogen production from cornstalk, fungal pretreatment proved to be the optimal method. It is apparent that besides high hydrogen production efficiency, fungal pretreatment also offered several advantages over other pretreatments such as being environmentally benign and energy efficient. This pretreatment method thus has great potential for application in consolidated bioprocessing performance of hydrogen production.

     

植物次生细胞壁生物合成的转录调控网络

植物次生细胞壁包含纤维素、半纤维素和木质素, 赋予细胞壁机械强度及疏水性, 这种特性对植物直立生长、水分和营养物质运输以及抵御生物和非生物胁迫十分重要。该文总结了调控次生细胞壁生物合成的转录因子及其调控机制, 包括NAC转录因子调控次生壁合成的一级开关作用, AtMYB46/AtMYB83及其下游调控因子的二级开关作用, 以及其它转录因子对次生壁生物合成的调控作用, 并对未来研究内容和方法进行了展望, 以期为深入系统理解次生细胞壁生物合成的转录调控网络提供参考。     

Expression of the human MHC, HLA-DQW6 genes alters the immune response in C57BL/6 mice

In an attempt to obtain direct evidence for the critical role of HLA class II molecules in regulating the immune response, genomic genes for alpha- and beta-chains of HLA-DQw6 from HLA-Dw12 haplotype were introduced into the C57BL/6 (B6) strain of mouse and a line of HLA-DQw6 transgenic mouse was obtained. Tissue specificity of the expression of the transgenes was much the same as that of murine I-Ab genes. DQw6 molecules were expressed on B cells and macrophages in spleen cells and about 30 to 40% of the I-Ab+ spleen cells were positive for DQw6. The HLA-DQw6 transgenic B6 mouse became tolerant to the DQw6 molecules, as evidenced by the MLR and antibody production specific to the DQw6 molecules. The HLA-DQw6 transgenic B6 mouse showed a strong immune response to streptococcal cell wall antigen (SCW), whereas the B6 mouse was a low responder to SCW. The SCW-specific T cell line was established from the transgenic mouse and this T cell line recognized SCW in the context of HLA-DQw6 molecules expressed on the mouse L cell transfectant or on human monocytes. The proliferative response to SCW of primed lymph node T cells and the SCW-specific T cell line derived from the transgenic mice was inhibited by anti-HLA-DQ mAb. Thus, it is clear that the HLA-DQw6 genes acted as major histocompatibility genes in these transgenic mice.     

An IFN-gamma-independent proinflammatory role of IL-18 in murine streptococcal cell wall arthritis

IL-18 is a member of the IL-1 family of proteins that exerts proinflammatory effects. It was formally known as IFN-gamma-inducing factor and is a pivotal cytokine for the development of Th1 responses. Apart from Th1 immune-stimulatory activity, IL-18 induces the production of proinflammatory cytokines such as TNF-alpha and IL-1 in vitro. The goal was to investigate the role of endogenous IL-18 in murine streptococcal cell wall (SCW)-induced arthritis. Furthermore, we investigated whether IL-18 neutralization had an impact on local TNF and IL-1 production. C57BL/6, BALB/c, and IFN-gamma-deficient mice were injected with 2 mg of rabbit anti-murine IL-18 Abs shortly before induction of arthritis by intra-articular injection of 25 microg of SCW fragments into the right knee joint. Suppression of joint swelling was noted on days 1 and 2 of SCW arthritis after blockade of endogenous IL-18. Analysis of local cytokine concentrations showed that IL-18, TNF-alpha, and IL-1ss levels were decreased. Severe inhibition of chondrocyte proteoglycan synthesis was seen in the vehicle-treated control animals, whereas a reversal of the inhibition of chondrocyte proteoglycan synthesis was found in the anti-IL-18-exposed animals. Blockade of endogenous IL-18 in IFN-gamma-deficient mice showed results similar to those found in wild-type animals, identifying a role for IL-18 that is IFN-gamma independent. The present study indicates that IL-18 is a proinflammatory cytokine during the onset of murine SCW arthritis, and this inflammatory role of IL-18 is IFN-gamma independent.     

Behavioral responses of Schistosoma mansoni miracidia in concentration gradients of snail-conditioned water.

Movement patterns of Schistosoma mansoni miracidia were examined in several concentrations and gradients of snail-conditioned water (SCW). Miracidia surrounded by uniform concentrations of SCW swam at the same speed and exhibited the same rate of turning (angular velocity) as did control miracidia swimming in spring water. However, miracidia in gradients of SCW exhibited a 3-fold increase in their angular velocity without altering their swimming speed. Miracidia ascending gradients of SCW did not increase their angular velocity and failed to orient to the gradient of the stimulant. In contrast, miracidia which encountered sufficiently abrupt decreases in SCW concentration, while descending the gradient, sharply increased their angular velocity. This behavior caused miracidia to remain in regions of high concentration of stimulant. The magnitude of decrease in SCW concentration needed to evoke this response depended on the absolute concentration of SCW. Thus, the miracidial response is a "boundary reaction", a form of chemoklinokinesis, and not a chemotaxis.     

微生物与能源的可持续开发

微生物技术在新能源开发领域中有广阔的应用潜力,对能源的可持续发展具有重要的理论和现实意义.简要叙述了生物柴油、燃料酒精、生物制沼气、生物制氢和微生物电池等新能源的原理、优缺点和开发现状,概述了微生物资源在能源领域的应用,指出发掘新的微生物资源或构建工程菌株、明确微生物作用机理、开发新工艺将会是今后研究的重点.