四氢萘热解中间产物及其反应机理的进一步研究

在四氢萘热解实验中,我们曾注意到,某些热解产物如甲基茚(?)和正丁基苯有进一步的反应.对这些中间产物做热解实验,无疑将为更全面了解四氢萘热解反应机理提供新的信息.对四氢萘热解反应,我们曾提出了自由基反应机理,在四氢萘中加入一些自由基引发剂,将会为自由基反应机理的假设提供一些实验上的旁证.     

On the Compensation Effect at the Form of the Differential Conversion Function

From the general form of the rate equation under non-isothermal conditions, some relationships showing the existence of a compensation effect due to the change of the analytical form of the differential conversion function were derived. These relationships were checked for some simulated TG curves, as well as thermogravimetric data corresponding to the degradation of some polymers and to the decomposition of calcium carbonate. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of oxide coatings on glass

Some representative characteristics of oxide films deposited on glass by different techniques have been briefly described as well as several relevant methods of thin-film analysis to determine these quantities. The most powerful information obtained by some analytical techniques have been given, and some typical problems that may occur during the analysis of oxidic thin films have been discussed. With a few selected results, the potential of some modern methods has been demonstrated.     

Characterization of oxide coatings on glass

Some representative characteristics of oxide films deposited on glass by different techniques have been briefly described as well as several relevant methods of thin-film analysis to determine these quantities. The most powerful information obtained by some analytical techniques have been given, and some typical problems that may occur during the analysis of oxidic thin films have been discussed. With a few selected results, the potential of some modern methods has been demonstrated.     

Titrimetric determination of hydrazines with sulfatoceric acid

Titrimetric methods for the determination of hydrazine and some simple alkyl and aryl derivatives are described. Iodine monochloride serves as pre-oxidant and indicator, and sulfatoceric acid as the titrant. Mercury(II) is added to ensure complete oxidation of some compounds.     

Utility of 6‐Amino‐2‐thiouracils as a Core of Biologically Potent Polynitrogen–Sulfur Fused Heterocycles

One pot three‐component reaction was assisted to form some new pyridopyrimidine derivatives to be investigated as antimicrobial and antitumor agents. The newly synthesized compounds showed high significant antimicrobial activity against the applied strains of both Gram‐positive and Gram‐negative bacteria and fungi. The cytotoxic activity of some compounds was evaluated as inhibitor of growth in both human liver carcinoma and breast cell lines. The results showed that some compounds exhibited very high cytotoxicity against human liver cell line and breast cancer cells.     

Conotoxins as research tools and drug leads

The complex mixture of biologically active peptides that constitute the venom of Conus species provides a rich source of ion channel neurotoxins. These peptides, commonly known as conotoxins, exhibit a high degree of selectivity and potency for different ion channels and their subtypes making them invaluable tools for unravelling the secrets of the nervous system. Furthermore, several conotoxin molecules have profound applications in drug discovery, with some examples currently undergoing clinical trials. Despite their relatively easy access by chemical synthesis, rapid access to libraries of conotoxin analogues for use in structure-activity relationship studies still poses a significant limitation. This is exacerbated in conotoxins containing multiple disulfide bonds, which often require synthetic strategies utilising several steps. This review will examine the structure and activity of some of the known classes of conotoxins and will highlight their potential as neuropharmacological tools and as drug leads. Some of the classical and more recent approaches to the chemical synthesis of conotoxins, particularly with respect to the controlled formation of disulfide bonds will be discussed in detail. Finally, some examples of structure-activity relationship studies will be discussed, as well as some novel approaches for designing conotoxin analogues.     

Photoelectron spectroscopy without photoelectrons: twenty years of ZEKE spectroscopy

Zero Kinetic Energy (ZEKE) spectroscopy, originally developed as a high resolution form of photoelectron spectroscopy, promised a means to the unambiguous determination of ionic (ro)vibrational states. Since its original development, it has spawned numerous methodological offshoots and has become one of the default methods of choice for high resolution spectroscopy of the ion. This tutorial review describes the historical development of the method, provides some insight into how it works and assesses the impact of the technique by reviewing some of the highlights of the past 20 years as well as some of the more recent developments and applications.     

Variations in atmospheric trace element deposition studied by INAA of peat cores from ombrotrophic bogs

In the present work INAA is used to determine as many elements as possible in peat samples from ombrotrophic bogs. Results for depth distribution profiles of some elements of particular interest are presented for selected bogs from areas with highly different input from long-range atmospheric transport of pollutants. In addition to information on air pollution, the data provide knowledge about contribution from natural processes to the airborne supply of some elements, such as in the case of selenium.     

评价混凝土中钢筋腐蚀的恒电量技术

本文综述了恒电量技术在混凝土中钢筋腐蚀上的应用研究 ,和其他化学技术相比较 ,可以认为恒电量技术具有测量速度快、反应灵敏、无损检测和近乎原位的腐蚀测量以及不受介质阻力影响等优点 .恒电量技术在研究钢筋的腐蚀中有着良好的应用前景 ,同时这种方法目前也还存在着有待解决的几个难点     

聚苯乙烯微球表面的聚集态结构和苯基堆砌

用扫描隧道显微镜(STM)研究微乳液聚合法制备的聚苯乙烯微球.STM图像显示这种聚苯乙烯微球的表面具有不同的聚集态结构.在表面的某些区域,聚合物链没有相互缠结现象,而是有序地堆积在一起.在适当的情况下,同一条链上的苯基还会堆砌起来,形成一种平行移位的结构,其类似于苯双分子的最稳定结构.还用STM研究了用苯溶胀过的聚苯乙烯粒子,并观察到了类似螺旋结构的聚合物链以及扭曲的聚合物链.在聚苯乙烯微球中,聚合物链段和苯基的有序堆砌状态的存在,是因为苯乙烯单体已经在微乳液内的某些区域堆砌成有序的状态.     

Complex scaling transformations in stationary and scattering problems

We review the methods and some applications of complex scaling transformation as well as some goals that now seem accessible using this technique in atomic and molecular physics.     

Environmental aspects of tributyltin

The tributyltin species, the active ingredient in some antifouling paint formulations, is perhaps the most acutely toxic chemical to aquatic organisms ever deliberately introduced to water. It has been demonstrated to have an adverse effect on shellfish in France and England, and as a consequence the use of tributyltin-containing antifouling paints has been restricted in these countries. Other countries have banned the use of tributyltin-containing antifouling paints or are contemplating restrictions. This article reviews such environmental aspects of tributyltin as methods of analysis, toxicity, environmental occurrence, persistence and fate. Tributyltin concentrations in many locations may be high enough to cause chronic toxicity or harmful effects in some aquatic organisms, and in some locations the tributyltin concentrations may be high enough to be acutely toxic to some organisms. Biological degradation of tributyltin in water and sediment appears to be the most important factor limiting the persistence of tributyltin in aquatic environments. To some degree, then, the persistence of tributyltin in aquatic environments depends upon the nature of the ecosystem. Tributyltin exhibits low-to-medium persistence in water and moderate persistence in sediment. A summary is given of the regulatory status of tributyltin in some countries, and recommendations are made for further research.     

钨青铜型铌酸钡钠晶体生长条纹的结构成因与克服途径

作者通过对类钙钛矿和钨青铜型结构晶体生长条纹的分析和观测研究,认为这类晶体属于未填满型结构,存在着结构空位,因而易于在晶体生长过程中引起杂质或其它多余组份进入结构空位而形成生长条纹。这类生长条纹将严重影响晶体的光学质量。实验表明,可以采用掺入少量无害元素,如硼(B_2O_3)填占BNN晶体的空位结构以克服生长条纹,取得了初步成效。     

等离子体引发聚合的机理初探

等离子体引发聚合与常规自由基聚合存在许多不同之处。本文从等离子体引发聚合物一些现象,如较强的溶剂效应、极高的单体选择性、主成超高分子量聚合物等方面,系统介绍了等离子体引发聚合的机理研究成果,并提出了自己的看法。     

Improved addition of organolithium reagents to hindered and/or enolisable ketones

A study of the addition of some aryl- and alkyllithium derivatives to some hindered and/or enolisable ketones in different solvents (polar and apolar) and, in some cases, at different temperatures and reaction times, will be presented here. The reversibility of the addition of aryllithium to these specific ketones will be observed and discussed. This approach is then used to prepare new steroids as precursor for potentially interesting substituted testosterones.     

Determination of Gold Content in Geological Samples by Atomic Absorption Spectrometry Method Applied after Separation of Gold by Tellurium or MIBK

Research has been carried out for the application of AAS method to determine gold content in geological samples. These samples usually contain mainly metal sulfides and quartz. Gold usually occurs in the samples as native gold in free state or in joints of some other minerals. The gold grain size is usually below 0.01 mm to over 1 mm and the gold content varies from some ppb to some tens of g/t.     

New cleft-like molecules and macrocycles from phosphonate substituted spirobisindanol

We have synthetized medium-sized cyclophanes and macrocycles containing phosphonic groups, directly linked to the aromatic rings of the phanes or as pendant arms,for use as specific receptors for the selective complexation of neutral guests or for complexing lanthanides, as luminescent sensors and for diagnostic bioassays in medicine.Furthermore, because it would be of great interest for biochemistry as well as for pharmacological studies to dispose of preorganized rigid chiral hosts for biorelevant molecules we designed inter alia, some new chiral macrocycles capable of a triple binding mode and we used them for constructing macrocycles that could also be of interest for chiral recognition and chiral separations. Thus, in this paper we shall review the salient aspects of some macrocycles synthetized in our laboratory, all possessing the phosphonate moiety and a spirobisindanol scaffold and able to act as complexing agents for cations and organic substrates. In particular, we shall describe their NMR characterization, their stereochemistry in solution and in the solid state, and their use as chiral receptors for biorelevant molecules. Chiral HPLC resolution of some of them is also reported.     

Asymmetric multicomponent reactions (AMCRs): the new frontier

Asymmetric multicomponent reactions involve the preparation of chiral compounds by the reaction of three or more reagents added simultaneously. This kind of addition and reaction has some advantages over classic divergent reaction strategies, such as lower costs, time, and energy, as well as environmentally friendlier aspects. All these advantages, together with the high level of stereoselectivity attained in some of these reactions, will force chemists in industry as in academia to adopt this new strategy of synthesis, or at least to consider it as a viable option. The positive aspects as well as the drawbacks of this strategy are discussed in this Review.     

皮革的CO2超临界流体脱灰

浸灰和脱灰是皮革制造过程的重要工序。在浸灰工序中,通过高浓度石灰乳液对动物皮的长时间处理,使其纤维介质被溶解,胶原纤维得到分散。脱灰是其后续工序,目的是除去动物皮中吸附和沉积的Ｃａ2+;调节ｐＨ值至中性并使其肿胀状态得以消除;促进鞣铬剂的发渗而与胶原纤维有效结合。常规制革工艺中,铵盐被广泛用作脱灰剂,其缺点是中和作用不充分不能有效除去Ｃａ2+,Ｃａ2+与动物油脂反应会产生“钙斑”,并产生令人不愉快的氨污染环境。而硼酸、甲酸、乙酸、柠檬酸等以单独或组合方式与铵盐一道用于脱灰[1]价格昂贵,还易引起裸皮的酸肿影响皮…