流化床热解煤焦油的降黏研究

对循环流化床热电气焦油多联产热解所得煤焦油流动性差的问题采取了一系列的降黏研究。通过X射线衍射测试可以排除室温下蜡结晶影响煤焦油黏度的可能,对比了煤焦油和煤沥青的黏度和族组分差异,考察了喹啉不溶物对软化点的影响,结果表明,采取馏分油降黏是合理的。分别添加四种馏分油对煤焦油进行了降黏实验,通过色谱质谱联机分析馏分油的成分,认为既含亲水基又含憎水基的分子具有很好的降黏效果,而且含量越多降黏效果越好。通过添加四种单组分化合物的降黏实验和分析,进一步验证了所得到的降黏理论,而且可以判断同时含有亲水基和憎水基的分子降黏效果优于只含憎水基不含亲水基的分子。     

Gemini表面活性剂的研究进展

Gemini型表面活性剂是一类双亲油基双亲水基的两亲物，因其特殊的二聚结构从而具有许多特殊的物化性质。综述了Gemini型表面活性剂的研究进展、合成方法、物化性质及其应用。     

含磺酸盐基两性分子／聚乙烯亚胺LB膜的聚集结构

气液界面聚离子复合结构的形成能减弱两性分手亲水基间静电排斥作用，增加单分子膜的稳定性和累积性能．Ｘ－射线衍射结果表明，纯水和聚乙烯亚胺水溶液表面上的ＺＣ１４ＳＮａ单分子膜在聚苯乙烯基片上累积成Ｙ型膜，两种ＬＢ膜的等同周期差约为０．３０ｕｍ．     

读者园地

读者来函询问在光度显色反应常加入OP、Triton X-100、Tween 80等试剂,但不知上述这些化学试剂是什么?其作用是什么?关于这些试剂在光度显色反应的作用问题,比较复杂,恐难以短文所能讲清。现先将上述这些化合物是什么这一问题作一介绍。 上面所提到的几种物质均属非离子型表面活性剂。简单说来能显著降低水的表面张力的物质称为表面活性剂。从分子结构看,表面活性剂的一个共同特点,即是它们的分子都是由极性的亲水基(hydrophilic group)和非极性的憎水基(hydrophobic group)两部分所组成。就非离子表面活性剂而言,是含有在水中不离解的羟基-OH和醚键结合,—O—,并以它为亲水基的一类表面活性剂。按分子中的亲水基分类,有聚乙二醇型和多元醇型之分。OP即属于聚乙二醇型,它的结构式见下:Triton X—100结构式见下:     

两亲性高分子量壳聚糖的合成与表征

以壳聚糖与环氧乙烷为原料制备亲水性0-羟乙基壳聚糖,进一步再与N-丁二酰羟亚胺基棕榈酸酯在避光下反应,获得了两亲性高分子量壳聚糖,并通过红外光谱、核磁共振氢谱确定了目标化合物的结构。探讨了两亲性壳聚糖亲油基的结构及其与亲水基比例对壳聚糖分子量及两亲性能的关系。     

双酚A型环氧树脂水基化微粒分析

高分子树脂水基化微粒化就是使高分子树脂以微粒形式分散于水中,高分子乳液、悬浮液都属于此范畴．因其不含有机溶剂,且具有无环境污染及不易失火等优点,放这方面的研究正成为高分子技术的一个研究热点．通常的乳液聚合或悬浮聚合方法是从小分子单体到聚合物水基化体系的化学反应过程,一般只适于制备加聚物的水基化体系,而不适用于制备维聚物的水基化体系．本文提出的相反转技术是一种有效的制备高分子水基化体系的方法,它能将几乎所有的高分子树脂通过物理的乳化方法制成相应的水基化体系[1,2],大大拓宽了其制备范围．相反转[3。4]…     

基于离聚体的自乳化型水基微乳液研究进展

：本文对近几十年来的以离聚体为基的两亲型高聚物水基微乳液的研究状况进行了综述，介绍了这类方法的特点，总结了影响相反转因素、影响微乳液性质的因素等。对水基微乳液的性能和应用前景等也作了简要介绍。     

疏水缔合聚合物在石英砂表面的吸附——疏水基含量和微嵌段长度对吸附的影响

研究了不同分子结构的疏水缔合聚合物和部分水解聚丙烯酰胺在45、55和65 ℃下的静态吸附特征。 实验结果表明,疏水缔合聚合物的疏水基含量和微嵌段长度可以改变聚合物在石英砂表面的最大吸附量,而其中疏水基含量是主要影响因素,等温吸附曲线出现2个平台区。 随着温度的升高, 部分水解聚丙烯酰胺吸附量增大,而缔合聚合物则表现出相反的规律;缔合聚合物通过改变疏水基含量和微嵌段长度来影响其吸附性能。     

聚氧烯醚及其硬脂酸酯类的消泡效力与亲水基的含量和亲水亲油平衡值的关系

聚氧烯醚嵌段聚合物及其硬脂酸酯类表面活性剂作为优良的消泡剂用于抗生素、谷氨酸发酵和其它行业中^[1~4]。作者曾研究过一些聚氧烯甘油的消泡效力^[5~6]。证明以二硬脂酸酯(GPES-2)的消泡效力最高^[7]。本文研究的是GPE和GPES-2分子中亲水基(聚氧乙烯基,EO)的含量及亲水亲油平衡值(HLB)与消泡效力的关系。     

水基纳米聚硅乳液的制备及增注性能研究

选用复配表面活性剂,用水代替柴油作为携带介质,将超疏水的纳米聚硅均匀稳定地分散在水中,制备成水基纳米聚硅乳液.室内试验结果表明:所制备的水基纳米聚硅乳液的分散性和稳定性较好,制备过程简单易行,便于实现工业化生产.粒径为10 nm左右的SiO2微粒在水中分散良好,该乳液遇盐发生破乳,释放出来的纳米聚硅微粒粒径在5～10 ...     

Nanoantioxidants: Pioneer Types,Advantages, Limitations,and Future Insights

Free radicals are generated as byproducts of normal metabolic processes as well as due to exposure to several environmental pollutants. They are highly reactive species, causing cellular damage and are associated with a plethora of oxidative stress-related diseases and disorders. Antioxidants can control autoxidation by interfering with free radical propagation or inhibiting free radical formation, reducing oxidative stress, improving immune function, and increasing health longevity. Antioxidant functionalized metal nanoparticles, transition metal oxides, and nanocomposites have been identified as potent nanoantioxidants. They can be formulated in monometallic, bimetallic, and multi-metallic combinations via chemical and green synthesis techniques. The intrinsic antioxidant properties of nanomaterials are dependent on their tunable configuration, physico-chemical properties, crystallinity, surface charge, particle size, surface-to-volume ratio, and surface coating. Nanoantioxidants have several advantages over conventional antioxidants, involving increased bioavailability, controlled release, and targeted delivery to the site of action. This review emphasizes the most pioneering types of nanoantioxidants such as nanoceria, silica nanoparticles, polydopamine nanoparticles, and nanocomposite-, polysaccharide-, and protein-based nanoantioxidants. This review overviews the antioxidant potential of biologically synthesized nanomaterials, which have emerged as significant alternatives due to their biocompatibility and high stability. The promising nanoencapsulation nanosystems such as solid lipid nanoparticles, nanostructured lipid carriers, and liposome nanoparticles are highlighted. The advantages, limitations, and future insights of nanoantioxidant applications are discussed.     

TXRF, PIXE, SYXRF; Principles, critical comparison and applications

Summary At first glance X-Ray fluorescence analysis seems to be a very sensitive and effectful method to detect element traces in the multielement mode. But in praxi the application range is restricted, if X-Ray tubes are used as excitation sources. To overcome this situation, it is necessary to improve the conditions of excitation and to reduce the background, produced by different scattering effects. TXRF, PIXE and SYXRF, which allow multielement analysis in the trace- and ultratrace region are using this strategy. In the case of TXRF a remarkable background reduction is achieved if the sample is prepared as a thin amorphous film on a planar sample holder and the excitation beam of a X-Ray tube is totally reflected on its surface. In the case of PIXE a particle beam of high intensity is used as excitation source, improving the conditions of excitation and giving the opportunity of spatial resolved analyses. In the case of SYXRF the X-Ray fraction of synchrotron radiation is used as excitation source, giving the opportunity, to improve the conditions of excitation as well as to reduce the background by using the high polarisation of the beam. In this case, too, spatial resolved analysis are possible. The principles of the three methods are described, their advantages and disadvantages are critically compared and advanced applications from different analytical fields are presented.     

Lasso peptides: structure, function, biosynthesis, and engineering

Covering: up to May 2012Lasso peptides are a class of ribosomally-synthesized and posttranslationally-modified natural products with diverse bioactivities. This review describes the structure and function of all known lasso peptides (as of mid-2012) and covers our current knowledge about the biosynthesis of those molecules. The isolation and characterization of lasso peptides are also covered as are bioinformatics strategies for the discovery of new lasso peptides from genomic sequence data. Several studies on the engineering of new or improved function into lasso peptides are highlighted, and unanswered questions in the field are also described.     

Phonon, IR, and Raman spectra, NMR parameters, and elastic constant calculations for AlH3 polymorphs

The electronic structure, lattice dynamics, and mechanical properties of AlH(3) phases have been studied by density functional calculations. The chemical bonding in different polymorphs of AlH(3) are evaluated on the basis of electronic structures, charge density analysis, and atomic charges, as well as bond overlap population analysis and the Born effective charges. The phonon dispersion relations and phonon density of states of all the polymorphs of AlH(3) are calculated by direct force-constant method. Application of pressure induces seqauence of phase transitions in β-AlH(3) which are understood from the phonon dispersive curves of the involved phases. The previously predicted phases (Chem. Mater. 2008, 20, 5997) are found to be dynamically stable. The calculated single crystal elastic constants reveal that all the studied AlH(3) polymorphs are easily compressible. The chemical bonding of these polymorphs have noticeable covalent character (except the hp2 phase) according to the present chemical bonding analyses. For all these polymorphs, the NMR-related parameters, such as isotropic chemical shielding, quadrupolar coupling constant, and quadrupolar asymmetry, are also calculated. All IR- and Raman-active phonon frequencies, as well as the corresponding intensities, are calculated for all the AlH(3) polymorphs and are compared with available experimental results.     

Polyarylsulfones,synthesis and properties,

A new class of high molecular weight polyarylsulfones is described. Polymer synthesis and structure–property relationships are discussed. The polymers are prepared by Friedel-Crafts type polycondensation of aromatic sulfonyl chlorides with aromatic hydrocarbons. A number of Lewis acids in small quantities are useful as catalysts for the polymerization. The polymerization reaction is carried out at elevated temperatures in the melt or in solution. Inert, nonbasic solvents which are compatible with the Lewis acid catalysts such as nitrobenzene and dimethyl sulfone are useful for conducting the polymerization. Many of the polyarylsulfones are amorphous, rigid thermoplastics with unusually high softening points, having glass transition temperatures in the range of 200–350°C. Outstanding resistance to air oxidation at high temperatures is derived from incorporation of the deactivating sulfone groups in the aromatic polymer backbone. Melt stability and solubility in selected solvents are emphasized as basis for processibility by conventional solution casting and molding techniques. The combination of properties, which in addition to thermal stability includes a high level of mechanical and electrical properties, chemical inertness, and hydrolysis resistance makes these new arylsulfone polymers useful over a wide temperature range and in severe and corrosive environments.     

Sulfotransferases: structure, mechanism, biological activity, inhibition, and synthetic utility

The sulfonation (also known as sulfurylation) of biomolecules has long been known to take place in a variety of organisms, from prokaryotes to multicellular species, and new biological functions continue to be uncovered in connection with this important transformation. Early studies of sulfotransferases (STs), the enzymes that catalyze sulfonation, focused primarily on the cytosolic STs, which are involved in detoxification, hormone regulation, and drug metabolism. Although known to exist, the membrane-associated STs were not studied as extensively until more recently. Involved in the sulfonation of complex carbohydrates and proteins, they have emerged as central players in a number of molecular-recognition events and biochemical signaling pathways. STs have also been implicated in many pathophysiological processes. As a result, much interest in the complex roles of STs and in their targeting for therapeutic intervention has been generated. Progress in the elucidation of the structures and mechanisms of sulfotransferases, as well as their biological activity, inhibition, and synthetic utility, are discussed in this Review.     

Muscarine, imidazole, oxazole, and thiazole alkaloids

The occurrence, structure determination, biological activities, as well as total syntheses of muscarine, imidazole, oxazole and thiazole alkaloids have been reviewed. The literature covers from the middle of 2001 to the end of 2002, and 149 references are cited.     

Hairs,criminals, moonrocks,metals diseases,polluters! Where next for nuclear analytical chemistry?

Nuclear methods of analysis have advanced dramatically in recent years, and in many ways, techniques that once were viewed as a scientific curiosity and the toys of a few scientists working in large nuclear research establishments, are now semi-routine and can be applied even by young students. Large amounts of good analytical data are outputted from instruments having sophisticated embedded software. It is interesting to speculate on the directions that nuclear analytical techniques may take next: whether more multielement; more automation for vastly larger sample suites; extension to minor and major components of samples as well as trace components; coupling of nuclear methods to hyphenated methods. However, in some respects the resources needed to continue to develop and apply radioanalytical methods are on the wane: reactors and accelerators are being closed and fewer radiochemical specialists are being trained. The open question, is whether instrumental analysis techniques will offer more and better results with less effort, or be less equipment intensive? In this paper some personal reflections on nuclear actcivation methods and their trends are presented and discussed. Some mileposts in the development of the field and some unique and interesting applications (as implied by the paper title) are cited and discussed.     

Big,Strong, Neutral,Twisted, and Chiral π Acids

General synthetic access to expanded π‐acidic surfaces of variable size, topology, chirality, and π acidity is reported. The availability of π surfaces with these characteristics is essential to develop the functional relevance of anion–π interactions with regard to molecular recognition, translocation, and transformation. The problem is that, with expanded π surfaces, the impact of electron‐withdrawing substituents decreases and the high π acidity needed for strong anion–π interactions can be more difficult to obtain. To overcome this problem, it is herein proposed to build large surfaces from smaller fragments and connect these fragments with bridges that are composed only of single atoms. Two central surfaces for powerful anion–π interactions, namely, perfluoroarenes and naphthalenediimides (NDIs), were selected as fragments and coupled with through sulfide bridges. Their oxidation to sulfoxides and sulfones, as well as fluorine substitution in the peripheral rings, provides access to the full chemical space of relevant π acidities. According to cyclic voltammetry, LUMO levels range from ?3.96 to ?4.72 eV. With sulfoxide bridges, stereogenic centers are introduced to further enrich the intrinsic planar chirality of the expanded surfaces. The stereoisomers were separated by chiral HPLC and characterized by X‐ray crystallography. Their topologies range from chairs to π boats, and the latter are reminiscent of the cation–π boxes in operational neuronal receptors. With pentafluorophenyl acceptors, the π acidity of NDIs with two sulfoxide groups in the core reaches ?4.45 eV, whereas two sulfone moieties give a value of ?4.72 eV, which is as low as with four ethyl sulfone groups, that is, a π superacid near the limit of existence. Beyond anion–π interactions, these conceptually innovative π‐acidic surfaces are also of interest as electron transporters in conductive materials.     

Polysulfide Polymers: Synthesis,Blending, Nanocomposites,and Applications

Abstract

Polysulfide polymers as an important class of polymers are used in different applications as sealants, adhesives, etc. They are usually synthesized by reaction of disodium polysulfides with dihalo compounds to yield liquid or solid polymers. Their most important advantages are excellent adhesion to different surfaces, creation of no defect in sealant under stress and pressure, resistance against to fuels and solvents, very low gas and steam permeability, and high resistance to ozone and UV. This article aims to review methods of synthesis, properties, and applications of polysulfide polymers. Also, polysulfide-based nanocomposites and blends are also briefly discussed.