Preface: Toxicity of Monomer and Combustion Products

During the last few years, the use of PVC has aroused questions owing to environment problems. Two major concerns are the toxicity of the monomer, which may lead to liver cancer and eventually to death, and the formation of toxic products in fires involving plastic building materials. A special session of this Second International Symposium on PVC, sponsored by both IUPAC and the French CNRS, is therefore devoted to these problems.     

Overview of Special Session B—Compositional and Structural Analysis of Biomass

Special Session B at the 29th Symposium on Biotechnology for Fuels and Chemicals was the first invited session at this symposium devoted to analytical methods. The special topic was added in response to numerous requests for information on new and innovative methods that could be applied in the growing renewable fuels industry. Presentation topics include analytical methods for the characterization and analysis of maize traits, tools for investigating cell wall limitations to enzymatic degradation, methods for customizing enzyme cocktails for biomass, new techniques for the analysis of carbohydrates, analytical methods that enhance our understanding of pretreatment, improved methods for monitoring process intermediates, and published standard analytical methods for biomass conversion processes.     

High-performance liquid chromatographic determination of xanthohumol in rat plasma, urine, and fecal samples

Xanthohumol (XN) is the major prenylated flavonoid in hop plants and as such a constituent of beer. Pharmacological studies have shown that XN possesses marked antioxidant and antiproliferative effects. In order to study the resorption and metabolism of this compound, reversed-phase high-performance liquid chromatography is used for the determination of XN in rat plasma, urine, and feces. In session one, rats receive either oral or intravenous (iv) administration (20 mg/kg body weight) of XN. In session two, rats receive oral administration of 50, 100, 200, 400, and 500 mg/kg body weight XN for bioavailability studies at various dose levels. Plasma, urine, and feces are collected at varying time points and assayed for their XN content. Plasma levels of XN fell rapidly within 60 min after iv administration; no XN is detected in plasma after oral administration in either session. XN and its metabolites are excreted mainly in feces within 24 h of administration. The method is a reliable tool for performing studies of XN in different biological material.     

Phototherapy on the Treatment of Burning Mouth Syndrome: A Prospective Analysis of 20 Cases

The aim of this study was to report the effect of laser phototherapy (LPT) on the treatment of burning mouth syndrome (BMS). This prospective clinical study reports on preliminary outcomes of twenty volunteers diagnosed with BMS who have undergone the conventional treatment prior to laser phototherapy. LPT consisted of weekly sessions of LPT (660 nm), for a period of 10 weeks. The laser protocol consisted of the following parameters: 40 mW, 10 J cm² and 0.4 J per point, irradiation time of 10 s. In all sessions, the burning intensity was evaluated with a 10 cm Visual Analogue Scale (VAS). The burning intensity evaluation by VAS was performed immediately before and after each LPT session. Nonparametric test of Wilcoxon was used for statistical analysis, considering a significance level of 5%. All volunteers reported reduced burning intensity in all sessions when compared to the previous one and reduction in VAS scores by up to 49% in the last clinical session when compared to the first session. When only the VAS baseline of the first session was compared with the consecutive sessions, there was a statistically significant reduction in VAS scores in almost all sessions. The LPT may be an alternative treatment for the relief of oral burning symptoms in patients with BMS.     

Introduction to the EU-network on trace element speciation: preparing for the 21st century

The main objective of the EU-network is to bring together scientists with a background in analytical chemistry interested in speciation method development with potential users from industry and representatives from legislative bodies. The network started on 1/10/1997 for a duration of 2 years. A series of meetings are being organised to debate all the important questions for collecting information on environmental, food and occupational health aspects of speciation and to define possible future projects. The findings and conclusions will be summarised as a series of general papers that will be published in the open literature, recapitulating the essential information gathered to date, outlining the state of the art for each topic and recommending legislative actions. A first meeting was held in Überlingen, Germany on 5–6 December 1997. The representatives from industry explained their interest in the network and the participants from the academic and national institutes gave a state-of-the-art presentation of their research. Out of this, a program was compiled for the following meeting in Segovia from 16 to 20 March 1998. The topics dealt with were: organotin compounds in the environmental session; the speciation and bioavailability of trace element species (Cr, Fe, Se), the quality of the data and new legislation in the food session; and identification of inhaled particles and the search for bioindicators for exposure to Ni and Pt in the occupational health/hygiene session. In each session about half of the participants came from industry. The delegates agreed on a list of priorities in speciation analysis. A www-page has been created: hhtp://www. speciation 21.plymouth.ac.uk. Everybody interested in adding information to the page is requested to mail this to lpitts@plymouth.ac.uk     

Water and biomolecules: an introduction

As an introduction to the eighth session ‘Water and Biosystems’ of the XVth ‘Horizon in Hydrogen Bond Research’, water molecules are presented with the stress on some elusive points which justify the existence of a session devoted to this topics. Thus, despite its familiar character, H₂O is a molecule which remains still poorly known, especially when it is part of large orderless systems such as liquid water or macromolecules. It is then difficult to observe it. It has consequently for long been ignored despite the fundamental role it may play, in biosystems for instance. The central importance it has in the reactivity of aqueous sytems is evocated, with a particular emphasis on the difference between proton transfers, which are encountered in the chemistry of acid/base in water, and H atoms transfers in cyclic hydrogen bonded structures by tautomerism. Arguments are given which suggest that this latter mechanism is the basic mechanism in bioreactivity and that it is the presence of water molecules that makes it efficient. In the final part the different lectures delivered during this session are presented in the line of this viewpoint.     

Analysis of primary aromatic amines in the mainstream waterpipe smoke using liquid chromatography-electrospray ionization tandem mass spectrometry

In recent years waterpipe smoking has spread worldwide and emerged as global health issue. Yet only little is known on the composition of waterpipe smoke. Here, we present a study on the identification and quantification of primary aromatic amines (PAAs) in this complex environmental matrix. Smoking of the waterpipe was conducted with a smoking machine and particulate matter was collected on glass fiber pads. We developed a fast, simple and specific liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) approach to simultaneously detect 31 different PAAs in this matrix. The detection limits comprised a range of 0.45-4.50 ng per smoking session, represented by 2-aminobiphenyl and 3,4,5-trichloroaniline, respectively. Intra- and inter-day precision were determined and proved excellent. We detected 31.3 ± 2.2 ng aniline and 28.0 ± 1.6 ng 4,4'-oxydianiline in the smoke of one waterpipe session. The water in the bowl exerted a small but considerable filter effect on PAAs. The method worked-out showed excellent sensitivity and specificity and is thus highly suited for the determination of PAAs in mainstream waterpipe smoke.     

Implementation of artificial intelligence for automatic drug design. I. Stepwise computation of the interactive drug-design sequence

In this article we represent the development of an artificial-intelligence-based method for the automatic design of valid chemical structures (AISD). The key feature of the proposed algorithm is its ability to mimic many decision-making processes carried by the human drug designer during a design session. The manual drug-design process is analyzed and transformed into a computerized form by associating a weight factor with each term. These weights enable the translation of the drug designer's intution into probabilities that control the flow of the design process. The input required to initiate a design session might be as minimal as the geometry of a previously existed pharmacophoric model, up to the three-dimensional geometry of the host receptor. A design application is demonstrated by the implementation of the proposed algorithm for the design of new potent sweeteners. © 1994 by John Wiley & Sons, Inc.     

A journey through quality control

The Euroanalysis VII conference in Vienna included a two-day session: Quality Assurance in Analytical Chemistry. The contributions comprised 15 lectures devoted to: intra-laboratory quality measures, inter-laboratory control, formal aspects and accreditation and implementation. The paper presents an overview of the main items developed by the contributors.A survey on the session on Quality Assurance in Analytical Chemistry of Euroanalysis VIIThe authors thank the organizers of EUROANALYSIS VII and in particular Dr. B. Griepink and Dr. E. Maier of the Community Bureau of Reference (BCR) of the CEC for their support and considerable contributions.     

Report On ‘The Sophomore Physical and Inorganic Courses’

The faculty in a small, progressive chemistry department have joined to revise and redefine its undergraduate program. In this session, Dr. Scudder examined the consequences of these changes in the context of organic chemistry instruction as well as the nature of the change.     

无机化学实验成绩评价标准与考核方式初探

根据我院实际情况,对无机化学实验考核方式进行了探讨,将实验教学考核成绩分成平时成绩、阶段成绩和结课成绩三个部分,建立了注重实验结果的同时更注重实验过程及实验技能的考核体系。     

《共同纲领》与新中国的不成文宪法（1949−1954）

统一战线与政治协商会议各有各的历史传统,它们是在1948−1949年新的政治协商会议筹备过程中逐步被认知并结合起来的,从而使得统一战线获得政治协商会议这种组织形式,而政治协商会议也因此获得了新的基础与性质。中国人民政治协商会议第一届全体会议具有双重属性,既作为统一战线的组织形式,又作为全国人民代表大会的临时代行机关,这种双重属性决定了“三大文件”不同的性质与功能。《政协组织法》和《共同纲领》本质上是党派间的政治合意,是政协作为统一战线组织形式的自我立法,《政府组织法》建构了中央人民政府,在内容上更接近于现代成文宪法,是政协第一届全体会议作为全国人民代表大会临时代行机关的政治决断。“三大文件”虽然具有不同的属性和功能,但共同构成中华人民共和国成立的法权基础,成为1949−1954年间中国的“不成文宪法”。     

The vascular disrupting agent 5,6-dimethylxanthenone-4-acetic acid improves the antitumor efficacy and shortens treatment time associated with Photochlor-sensitized photodynamic therapy in vivo

In this report, we examined the antitumor activity of photodynamic therapy (PDT) in combination with 5,6-dimethylxanthenone-4-acetic acid (DMXAA), a vascular disrupting agent currently undergoing clinical evaluation. BALB/c mice bearing subcutaneous CT-26 colon carcinomas were treated with PDT using the second-generation chlorin-based sensitizer, 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (Photochlor) with or without DMXAA. Long-term (60-days) treatment outcome, induction of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), vascular damage (microvessel density, MVD) were evaluated as endpoints. In addition, treatment selectivity was evaluated using magnetic resonance imaging (MRI) and the foot response assay. A highly synergistic interaction was observed with the combination of low-dose DMXAA and PDT (48 J cm⁻² at 112 mW cm⁻²) resulting in ∼60% long-term cures. The duration of the PDT session for this combination therapy protocol was only 7 min, while the duration of a monotherapy PDT session, selected to yield the equivalent cure rate, was 152 min. MRI showed markedly less peritumoral edema after DMXAA + short-duration PDT compared with long-duration PDT monotherapy. Similarly, DMXAA + PDT caused significantly less phototoxicity to normal mouse foot tissue than PDT alone. Increased induction of cytokines TNF-α and IL-6 ( P  < 0.001) was observed at 4 h followed by extensive vascular damage, demonstrated by a significant reduction in MVD at 24 h after combination treatment. In conclusion, Photochlor-sensitized PDT in combination with DMXAA exhibits superior efficacy and improved selectivity with clinically feasible illumination schemes. Clinical evaluation of this novel combination strategy is currently being planned.     

Constitution and energetics of photosystem I and photosystem II in the chlorophyll d-dominated cyanobacterium Acaryochloris marina

This mini review presents current topics of discussion about photosystem (PS) I and PS II of photosynthesis in the Acaryochloris marina. A. marina is a photosynthetic cyanobacterium in which chlorophyll (Chl) d is the major antenna pigment (>95%). However, Chl a is always present in a few percent. Chl d absorbs light with a wavelength up to 30 nm red-shifted from Chl a. Therefore, the chlorophyll species of the special pair in PS II has been a matter of debate because if Chl d was the special pair component, the overall energetics must be different in A. marina. The history of this field indicates that a purified sample is necessary for the reliable identification and characterization of the special pair. In view of the spectroscopic data and the redox potential of pheophytin, we discuss the nature of special pair constituents and the localization of the enigmatic Chl a.     

Gender Diversity in a STEM Subfield – Analysis of a Large Scientific Society and Its Annual Conferences

Speaking engagements, serving as session chairs, and receiving awards at national meetings are essential stepping stones towards professional success for scientific researchers. Studies of gender parity in meetings of national scientific societies repeatedly uncover bias in speaker selection, engendering underrepresentation of women among featured presenters. To continue this dialogue, we analyzed membership data and annual conference programs of a large scientific society (>7000 members annually) in a male-rich (~70% males), technology-oriented STEM subfield. We detected a pronounced skew towards males among invited keynote lecturers, plenary speakers, and recipients of the society’s Senior Investigator award (15%, 13%, and 8% females, respectively). However, the proportion of females among Mid-Career and Young Investigator award recipients and oral session chairs resembled the current gender distribution of the general membership. Female members were more likely to present at the conferences and equally likely to apply and be accepted for oral presentations as their male counterparts. The gender of a session chair had no effect on the gender distribution of selected applicants. Interestingly, we identified several research subareas that were naturally enriched (i.e., not influenced by unequal selection of presenters) for either female or male participants, illustrating within a single subfield the gender divide along biology-technology line typical of all STEM disciplines. Two female-enriched topics experienced a rapid growth in popularity within the examined period, more than doubling the number of associated researchers. Collectively, these findings contribute to the contemporary discourse on gender in science and hopefully will propel positive changes within this and other societies.

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Graphical abstract ?

     

Selective catalytic transformation of polystyrene into ethylbenzene over Fe-Cu-Co/Alumina

FeCuCo over aluminum oxide catalyst was prepared to catalytically degrade polystyrene (PS) into ethylbenzene (EB) under mild conditions. This catalyst was characterized by XRD, SEM, STEM-EELS, STEM-EDS, XPS, and physical properties. A significant selectivity toward EB formation at 250 °C was achieved in the absence of hydrogen with 82% liquid yield. End-chain session and cross-linking reactions are proposed to be the dominant pathways in the degradation of PS over FeCuCo to form EB.     

Hydrogen: Current issues in technology and chemistry (review)

Scientific communication presented at a session of the Presidium of the Academy of Sciences of the USSR, February 26, 1991.     

《超级电容器》专辑序言

超级电容器因具有高功率密度、长循环寿命和使用温度范围宽等显著优势,已成为化学电源产业内新的亮点。作为一种大功率储能器件,超级电容器在轨道交通、现代通讯、航空航天、国防等战略新兴领域具有广泛的应用前景,全球需求量迅速增长。目前,限制超级电容器规模应用的关键问题是其能量密度偏低以及成本过高。如何在保证其高功率密度和长循环寿命优势的前提下,提高超级电容器能量密度并降低其成本是当今研究的热点。近年来,全球的超级电容器研究者针对这一关键问题,从电极材料设计、新型电解液开发及器件构筑等方面开展了一系列的工作,从理论研究到工程应用都取得了重要的突破。本刊邀请了超级电容器领域内具有丰富研究经验的8个团队撰写了8篇关于超级电容器的综述或者研究论文,介绍了当前超级电容器领域的研究现状、发展趋势和所面临的挑战,希望籍此能使广大读者更加深入了解超级电容器这一领域,并共同推动我国超级电容器相关研究的进一步发展。在此,对本专辑的所有作者、审稿人及编辑部工作人员的卓有成效的工作和付出表示衷心的感谢！     

Surface treatment of PET fiber by EB-irradiation-induced graft polymerization and its effect on adhesion in natural rubber matrix

Aiming to develop a high performance fiber-reinforced natural rubber (NR) without using resorcinol formaldehyde latex (RFL) adhesives of environmental load substances, a special technique using electron beam (EB) irradiation-induced graft polymerization was applied to high-modulus polyethylene terephthalate (PET) fibers. Although PET is chemically inert, acrylate functional silane could be graft-polymerized onto the PET fiber surface by this special technique. The composite of NR and grafted PET fibers indicated a linear increase in the initial modulus with the fiber content. The fiber reinforced rubber with a good performance was obtained in the system of NR and grafted PET fibers.     

Introduction to Session 5

Applied Biochemistry and Biotechnology - This session is a new entrant into the Symposium series and highlights an emerging but important area of materials applications through...