Large-scale ethanol fermentation through pipeline delivery of biomass

Issues of traffic congestion and community acceptance limit the size of biomass-processing plants based on truck delivery to about 2 million (M) dry t/yr or less. In this study, the cost of ethanol from an ethanol fermentation plant processing 2 M dry t/yr of corn stover supplied by truck is compared with that of larger plants in the range of 4–38 M dry t/yr supplied by a combination of trucks plus pipelines. For corn stover, a biomass source with a low yield per gross hectare, the cost of ethanol from larger plants is always higher. For wood chips from the boreal forest, a biomass source with a relatively high yield per gross hectare, a plant processing 14–38 M dry t/yr produces ethanol at a 13% reduction in cost compared with a plant producing 2 M dry t/yr supplied by truck. Processing of value-added products, such as chemicals from lignin, would be enabled by larger-scale plants.     

Design of an experimental procedure for energy evaluation from biomass

The rational and sustainable exploitation of nature resources is one of the priority objectives of our society. In this article a method is proposed to evaluate and exploit the energetic resources contained in different forest formations. This method is based on the use of a combustion bomb calorimeter to determine the calorific values of the different samples studied. These results were complemented with chemical analysis of the samples and with environmental and geomorphological studies of the zones were samples were taken. The results obtained during the last 3 years for the residual biomass originated from the forest formations existing in Galicia ensure the reliability and usefulness of the method that can be extended to any forest formation all over the world.     

生物传感器研究进展

本文详细地综述了生物传感器的类型、基本原理、目前的研究现状及应用状况,并预测了其今后的发展趋势。参考文献110篇。     

Pilot-Scale Fermentation of Aqueous-Ammonia-Soaked Switchgrass

Aqueous-ammonia-steeped switchgrass was subject to simultaneous saccharification and fermentation (SSF) in two pilot-scale bioreactors (50- and 350-L working volume). Switchgrass was pretreated by soaking in ammonium hydroxide (30%) with solid to liquid ratio of 5 L ammonium hydroxide per kilogram dry switchgrass for 5 days in 75-L steeping vessels without agitation at ambient temperatures (15 to 33 °C). SSF of the pretreated biomass was carried out using Saccharomyces cerevisiae (D₅A) at approximately 2% glucan and 77 filter paper units per gram cellulose enzyme loading (Spezyme CP). The 50-L fermentation was carried out aseptically, whereas the 350-L fermentation was semiaseptic. The percentage of maximum theoretical ethanol yields achieved was 73% in the 50-L reactor and 52–74% in the 350-L reactor due to the difference in asepsis. The 350-L fermentation was contaminated by acid-producing bacteria (lactic and acetic acid concentrations approaching 10 g/L), and this resulted in lower ethanol production. Despite this problem, the pilot-scale SSF of aqueous-ammonia-pretreated switchgrass has shown promising results similar to laboratory-scale experiments. This work demonstrates challenges in pilot-scale fermentations with material handling, aseptic conditions, and bacterial contamination for cellulosic fermentations to biofuels.     

Quality management in analytical R&D in the pharmaceutical industry: Building quality from GLP

 The pharmaceutical industry is one of the most regulated activity sectors. The regulation includes specific quality systems such as good laboratory practice (GLP), good clinical practice (GCP) and good manufacture practice (GMP). The principles of GLP mainly cover the formal quality aspects of a procedure and do not evaluate the technical aspects in depth. On the other hand, EN 45001 accreditation covers technical performance and is not suitable for pharmaceutical research and development (R&D) as it is almost impossible to comply with the requirements of the European standard in the pharmaceutical environment. The challenge to the pharmaceutical industry is, therefore, to develop quality systems, compatible with GLP principles, that not only cover formal quality items but also ensure good scientific and technical performance. An implementation process focused on real quality improvement is the best way to achieve this objective, culminating in formal recognition of the quality system by third-party assessment. In the case of analytical R&D, the EURACHEM/CITAC Guide CG2 is a very good tool that can help in the definition, analysis and selection of the non GLP quality elements that will be useful. Received: 30 June 1999 / Accepted: 18 October 1999     

Thermal Plasma Technology: Where Do We Stand and Where Are We Going?

In this overview, an attempt is made to assess the present and future research and development in thermal plasma processing of materials restricted to (1) thermal plasma coating technologies, (2) thermal plasma synthesis of fine powders, (3) thermal plasma waste destruction, and (4) thermal plasma spheroidization and densification. Since thermal plasma processing is, in general, governed by a large number of parameters, implementation of controls becomes mandatory. The lack of sufficient controls combined with economic drawbacks in some cases has been the main obstacle for the growth of thermal plasma technology. Present R&D efforts, however, address these problems.     

中国纤维素乙醇技术的研究进展

中国面临着严重的能源短缺和环境污染问题,中国政府正在局部几个省份内政策性鼓励燃料乙醇生产和使用。尽管当前主要是用玉米和谷物作为生产乙醇的原料,然而中国具有大量潜在的低成本的纤维素生物质原料,可以极大地扩大乙醇的产量,降低原料成本。近20年来,由于技术的革命性进步,已使得纤维素乙醇的生产成本从4美元/加仑以上,降低至约1.2—1.5美元/加仑。其中,每吨生物质约44美元。因此,目前乙醇掺汽油具有十分强的市场竞争力。已有几个公司正在建造首批商业纤维素乙醇工厂,虽然这些刚起步的小型设施在合理利用和管理上风险较小,但规模经济需要较大型工厂。尽管配送生物质原料的成本会随需求的增加而增加,但在乙醇生产基础上的生物精炼技术的发展,尤其是化工产品和动力的协同生产,将会使全过程的经济可行性大大提高。进一步深入的基础研究,将解决低成本下实现纤维素的完全利用,以确保在无政策性补贴的前提下,真正使纤维素乙醇成为具有市场竞争力的低成本纯液体燃料。     

中国纤维素乙醇技术的研究进展

中国面临着严重的能源短缺和环境污染问题,中国政府正在局部几个省份内政策性鼓励燃料乙醇生产和使用.尽管当前主要是用玉米和谷物作为生产乙醇的原料,然而中国具有大量潜在的低成本的纤维素生物质原料,可以极大地扩大乙醇的产量,降低原料成本.近20年来,由于技术的革命性进步,已使得纤维素乙醇的生产成本从4美元/加仑以上,降低至约1.2-1.5美元/加仑.其中,每吨生物质约44美元.因此,目前乙醇掺汽油具有十分强的市场竞争力.已有几个公司正在建造首批商业纤维素乙醇工厂,虽然这些刚起步的小型设施在合理利用和管理上风险较小,但规模经济需要较大型工厂.尽管配送生物质原料的成本会随需求的增加而增加,但在乙醇生产基础上的生物精炼技术的发展,尤其是化工产品和动力的协同生产,将会使全过程的经济可行性大大提高.进一步深入的基础研究,将解决低成本下实现纤维素的完全利用,以确保在无政策性补贴的前提下,真正使纤维素乙醇成为具有市场竞争力的低成本纯液体燃料.     

Correlation of antioxidant depletion and mechanical performance during thermal degradation of an HTPB elastomer

Thermal degradation studies of a stabilized HTPB based elastomer were conducted at temperatures from 50 °C to 110 °C. The concentration of extractable antioxidant (AO2246) in the polymer was quantified via AO extraction and a gas chromatography-based method using internal standards. The decrease in extractable AO levels as a function of time and temperature was evaluated and correlated with mechanical property changes. Most importantly, AO depletion features were found to be temperature dependent. At elevated temperatures (>80 °C) extractable AO levels decreased rapidly and faster than the concurrent loss in mechanical properties. While extractable AO concentrations decrease quickly, the material is able to maintain some useful mechanical properties, perhaps via non-extractable or grafted AO species formed during degradation providing additional protection. At lower aging temperatures extractable or free AO levels decreased more slowly than the mechanical properties. Therefore, for condition monitoring purposes a universal correlation between AO levels and aging state or material condition could not be established. Most importantly, however, loss of mechanical properties and oxidative degradation is observed at lower temperatures despite significant levels of free antioxidant in the material. The antioxidant appears to be limited in its effectiveness to completely prevent degradation reactions, or only fractions of the total AO available are actually involved in the inhibition process.     

INDO Calculations with inclusion of an effective solvent field. Application to benzosemiquinones

Theoretical Chemistry Accounts - An INDO method extended to include a contribution from the solvent by means of an effective solvent field (ESF) is applied to the three isomeric benzosemiquinones...     

Development of an Integrated System for Immobilization and Mediating Charge to Alcohol Dehydrogenase During Bioelectrocatalytic Oxidation and Detection of Ethanol

A robust biocatalytic electrode film utilizing multiwalled carbon nanotubes intentionally derivatized with poly(diallyldimethylammonium chloride), PDDA, as well as integrated with alcohol dehydrogenase is considered here for potential application as a stable efficient anode in a biofuel cell and a specific working electrode in amperometric sensors. PDDA‐modified CNTs were characterized using transmission electron microscopy (TEM) and infrared spectroscopy (FTIR). Once immobilized on a glassy carbon electrode substrate, they facilitate not only distribution of charge but also immobilization of alcohol dehydrogenase molecules. The resulting integrated bioelectrocatalytic system was able to induce oxidation of ethanol and NADH as well as to produce relatively high currents at a fairly low potential.     

光催化研究与发展的文献计量分析

对ＣＡ１９６１－１９９６年期间卷双期号期刊中收录的与光催化有关的各种文献进行了详细的统计,结果表明,光催化研究正处于快速的发展期,以消除环境污染为目的应用研究是该快速发展期中的主题,日本,美国,俄罗斯和中国发表文献量居世界前４位。     

工科学校本科生科研训练与实践——以节能减排大赛为例

科研训练是本科生学习中必不可少的一个环节,在提升学生知识运用、科学素养等方面有着重要作用。本文将以"大学生节能减排大赛"的参赛过程为例,从学生的视角简要介绍高分子材料与工程专业本科生的科研训练,以及如何结合学科以及学校特色,将所学知识用于解决实际问题。     

教研员专业发展:现状、需求与建议*——广东省中学化学教研员专业发展调研

为充分了解教研员专业发展的现状与需求,探寻教研员专业发展与教研工作的有效策略,以广东省123名中学化学教研员为基础样本展开问卷调查,对14名化学教研员和一线教师展开访谈,对其基本信息、专业情意与状态、专业能力与发展及区域教研活动的组织情况进行关联分析,找寻其中的变化规律,了解问题与需求,为教研员的发展和教研工作的优质开展建言献策。     

酰胺电子等排体在先导化合物优化中的应用

生物电子等排体是指一类化合物或基团,这类物质拥有近似的分子形状和体积,类似的电子分布,并由此表现出相似的物理特性。作为激动剂或拮抗剂生物电子等排体能对相同的生化相关体系发挥作用,产生彼此互相相关的生物特性。药物结构中酰胺结构作为药效团和药物的重要组成部分被广泛应用。然而作为药物分子结构的重要组成部分,酰胺结构也存在着一些明显的缺点,包括代谢不稳定、代谢产物有毒和膜渗透性差等。为了克服这些缺点同时又想保持部分酰胺的特性,生物电子等排体替换是有效的方法之一。在先导化合物的优化过程中,通过酰胺生物电子等排体替换还能达到提高生物活性和靶点选择性、降低合成难度、扩展或突破知识产权限制等目的。本综述着重介绍了近五年来酰胺及其生物电子等排体在先导化合物优化过程中的应用。希望能对含有酰胺结构的先导化合物的优化提供新的思路,加速新药研发进程。     

从纸上到躬行:基于有机化学理论和文献的实验设计及优化之低年级本科教学初探

国际公认化学类本科生的培养目标是能够胜任化学专业技术职务,或具备相关的科研能力,而核心考核因素之一被认为是能否以纸上所学理论和文献助力实验方案的设计,并躬行实现。我们在有机化学基础实验教学中融合以上理念,初步探索出适合低年级本科生的以理论知识和文献指导实验设计和优化的教学策略。以乙酰二茂铁的合成为例,以问题-讨论为主线,引导学生从文献、底物的电子结构、傅-克酰基化反应机理和重要的物理化学性质等进行综合分析,设计乙酰二茂铁的合成路线,鼓励学生对教材提出质疑并自主设计和开展验证实验,对教材中的经典方法持续优化。学生深度参与实验路线设计和关键参数设置,沉浸学术研究氛围,敢于质疑并验证,提升了将已学理论转化为解决实际问题的能力,一定程度上有利于其科学思维和科研执行力的培养,提高其从事化学专业技术职务或相关科研工作的核心竞争力。     

Sense and nonsense of quality assurance in an R&D environment

Quality has always been one of the key issues in laboratories in general and formal quality assurance (QA) in testing laboratories has gained popularity over the last decade. However, the implementation QA in research and development (R&;D) laboratories is still the domain of a few pioneers. We can even ask whether a QA system in research makes sense at all and if such a system really provides any added value? Difficulties with respect to the implementation of such a system are mainly associated with the nature of the research process itself. However, it is obvious that QA offers clear advantages in R&;D, if some critical success factors have been taken into account. An important issue is the selection of a good QA standard for R&;D. This is certainly not an easy task, since there are no specific standards. Fortunately, some useful international guides have been published recently.     

Utilization of Physiologically Based Pharmacokinetic Modeling in Pharmacokinetic Study of Natural Medicine: An Overview

Natural medicine has been widely used for clinical treatment and health care in many countries and regions. Additionally, extracting active ingredients from traditional Chinese medicine and other natural plants, defining their chemical structure and pharmacological effects, and screening potential druggable candidates are also uprising directions in new drug research and development. Physiologically based pharmacokinetic (PBPK) modeling is a mathematical modeling technique that simulates the absorption, distribution, metabolism, and elimination of drugs in various tissues and organs in vivo based on physiological and anatomical characteristics and physicochemical properties. PBPK modeling in drug research and development has gradually been recognized by regulatory authorities in recent years, including the U.S. Food and Drug Administration. This review summarizes the general situation and shortcomings of the current research on the pharmacokinetics of natural medicine and introduces the concept and the advantages of the PBPK model in the study of pharmacokinetics of natural medicine. Finally, the pharmacokinetic studies of natural medicine using the PBPK models are summed up, followed by discussions on the applications of PBPK modeling to the enzyme-mediated pharmacokinetic changes, special populations, new drug research and development, and new indication adding for natural medicine. This paper aims to provide a novel strategy for the preclinical research and clinical use of natural medicine.