Am(III) adsorption on oxides of aluminium and silicon: effects of humic substances,pH, and ionic strength

The adsorption of Am(III) (total concentration 10(-9) mol/l) on alumina, silica, and hematite was studied by a batch technique. The effects of pH, ionic strength, and humic substances on the adsorption of Am(III) on alumina and silica were investigated, and the adsorption isotherms of Am(III) on alumina and silica at different pH values were determined. It was found that compared with the adsorption of Am(III) on alumina, the adsorbability of silica on the basis of mass is less, the relative adsorption rate on silica is slower, the sensitivity of adsorption on silica to ionic strength is less, the dependence of adsorption on silica on pH is gentler, and consequently that the adsorption characteristics of Am(III) on alumina and silica are distinctly different. The negative effect of fulvic acid on the adsorption on silica and the positive effect of humic acid on the adsorption on alumina were found. In contrast to the Am(III) adsorption on alumina and silica, a tremendously high adsorbability of Am(III) on hematite was found. The sequence of adsorbabilities of Am(III) on the basis of mass is Fe2O3 > Al2O3 > SiO2.     

Resonance Raman spectra of polyacetylene on zeolite and alumina surfaces

Raman spectra are reported for polyacetylene on exchanged zeolites and on alumina. The polymerization of acetylene on zeolites is found to depend on the zeolitic cation size and on surface coverage. Mean chain lengths of about fifteen CC bonds are formed on alumina.     

Anionic Graft Copolymers. III. Hydrogenation of Polydienes Grafted with Vinylaromatics

A new method is described to prepare graft copolymers of polystyrene and polyvinylcyclohexane on polyethylene and poly (ethylene, butene-1). Hydrogenation of the butadiene moieties of graft copolymers of polystyrene on poly-1, 4-butadiene and high vinyl polybutadiene forms graft copolymers of polystyrene on polyethylene and on poly (ethylene, butene-1). Graft copolymers of polyvinylcyclohexane on polyethylene and on poly (ethylene, butene-1) are prepared by completely hydrogenating graft copolymers of polystyrene on poly-1, 4-butadiene and on high vinyl polybutadiene. The physical properties of these polymer systems depend on composition and graft level, resulting in either tough polymers or elastomers.     

环取代基对金属化聚苯胺衍生物膜修饰电极性能的影响

通过比较聚2，5－二甲氧基苯胺（PDMAn）、聚邻甲基苯胺（POT）和聚间氯苯胺（PmClAn）膜修饰电极的氧化还原电位、沉积在这3种聚合物上的铂微粒的表面形态与晶面取向以及异丙醇在分散Pt微粒的聚苯胺膜修饰电极上的氧化行为，从电子效应和立体效应探讨了聚合物电化学性质与环取代基的关系以及不同聚合基质对Pt沉积机理和有催化性能的影响,结果表明，在硫酸溶液中PDMAn膜修饰电极的氧化还原电位最负、POT次之、PmClAn最正，Pt在PDMAn和POT膜上的电沉积机理与在PmClAn膜上的不同，聚合物膜上沉积的Pt微粒呈现（200)晶面择优取向，其中POT膜上择优取向度最大，PDMAn次之，Pm-ClAn最小，异丙醇在金属化聚合物膜电极上的氧化电位取决于聚苯胺的本质，在POT膜修饰电极上异丙醇的电氧化主要发生在POT的活性电位区，而在PDMAn与PmClAn膜上的电氧化则主要发生在Pt上的氧化电位区，说明聚合物膜不仅作为Pt微粒的分散介质，而且本身有产生催化作用。     

Layer-selective epitaxial self-assembly of porphyrins on ultrathin insulators

Copper-Octaethyl Porphyrin self-assembly has been studied on NaCl islands, 1–3 monolayers thick, grown on metal substrates. Extended ordered molecular monolayers are observed for the first time on ultrathin insulator films. The assembly occurs in hierarchical fashion, starting on the metal substrate, then followed by assembly on the first and second NaCl layers, clearly demonstrating a decrease in adsorption energy for increasing insulator layer thickness. The underlying mechanisms are discussed on the basis of molecule–substrate interactions. Voltage-dependent STM images reveal differences of the electronic structure for molecules adsorbed on metal and NaCl/metal areas.     

Recent progress in experiments for sessile droplet wetting on structured surfaces

Wetting of a sessile droplet on structured or patterned surface can be found in a broad range of applications. The researchers have been promoted to keep working on the topic. The review is on the basis of the recent experimental advances on the sessile droplet wetting on the hydrophobic, hydrophilic, or combined hydrophobic and hydrophilic surfaces under isothermal conditions, and on heating or cooling substrates having nonisothermal conditions. More attention has been paid on the wetting configuration between the sessile droplet and the structured substrate; the research gap has been discussed on identifying the three-phase line shape. Further, the three-dimensional measurement for the sessile droplets on the patterned surfaces with focusing more on the contact line of sessile droplets might reveal new physical insights. This review targets at building a holistic overview on the sessile droplet wetting behaviors on the structured substrate in the past 2 years.     

Influence of the precursors on the properties of alumina supported rhodium particles

The effect of chlorine on the properties of Rh particles supported on alumina was studied using the hydroconversion of alkanes as a molecular probe. Chloride ions on the alumina have little influence on the Rh particles. Chlorine adsorbed on the Rh particles decreases the chemisorption capacity and increases the metal-support interaction, which results in modifications of their catalytic properties. Depending on the alkane processed, specific activity can be depressed up to four orders of magnitude.     

Determination of complex reaction mechanisms. Analysis of chemical, biological and genetic networks

We present several methods of determining, not guessing, complex chemical reaction mechanisms and their functions. One method is based on the theory of correlation functions of measured time series of concentrations of chemical species; another is on measurements of temporal responses of concentrations to various perturbations of arbitrary magnitude; a third deals with the analysis of oscillatory systems; a fourth is on the use of genetic algorithms to determine functions of chemical reaction networks. All methods are applicable to chemical, biochemical, and biological reaction systems and to genetic networks and systems biology. The methods depend on the design of appropriate experiments on the whole system and corresponding theories for interpretation that lead to information on the causal chemical connectivity of species, on reaction pathways, on reaction mechanisms, on control centers in the system, and on functions of the system. The first three methods require no assumption of a model or hypothesis, nor extensive calculations, unlike the interpretation of measurements made on a gene network at only one time.     

化学发光酶免疫分析研究进展

叙述了化学发光免疫分析的分类及特点,从发光底物、增强剂、过氧化物酶、过氧化物及其他方面,对鲁米诺类化合物化学发光酶免疫分析的进展进行了综述,引用文献34篇。     

ToF‐SIMS and principal component analysis: Effect of film thickness on crystal surfaces of polymers

The effect of film thickness on the structural conformation of the surfaces of the amorphous state, edge‐on lamellae and flat‐on lamellae of a semiflexible polymer, poly(bisphenol‐A‐etheroctane), was investigated by time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) with the aid of principal component analysis (PCA). PCA results empirically indicate that a structurally regular polymer surface was obtained with the formation of the flat‐on lamellae from the amorphous state at a low degree of supercooling. A higher concentration of end group and cilium ion fragments, which are indicative of free chain ends, was observed on the edge‐on lamellar surfaces than on the amorphous and the flat‐on lamellar surfaces. This finding was attributed to the fact that the lateral surface of the edge‐on lamellae contains many growth fronts, leaving behind a large number of uncrystallized chain remnants on the surfaces. Structural disorder was facilitated on both edge‐on and flat‐on lamellar surfaces as the film thickness decreased. Hence, this PCA study offers new insights into the nonequilibrium nature of polymer crystals and the mechanism of polymer crystallization in thin and ultrathin films. Copyright © 2010 John Wiley & Sons, Ltd.     

Thermische und spektroskopische Untersuchungen zur Wassersorption an Alkalihalogeniden

Investigations on the extension of the diffuse reflectance spectroscopy by means of the dilution method of KORTÜM show the decisive influence of water sorption on the dilution substances, particularly on their absolute reflectance. Water sorption is investigated on alkali halides (NaCl and LiF) as dilution substances by gravimetric, thermal desorption and reflectance methods. Sorption gravimetry gives data on the quantities of adsorbed substances and the time function of adsorption processes, thermal desorption on chemical binding of adsorbed molecules and reflectance spektroscopy on the molar absorptivity of adsorbed water molecules.     

核酸的有机化学研究在分子生物学发展中的作用

本文主要综述有机化学在建立核酸的顺序测定法和自动顺序仪,在破译遗传密码,在建立核酸片段的化学合成方法,固相合成法及DNA合成仪的设计,在合成许多有生物活力的核酸分子,在发展并完善遗传工程以及新近发现酶RNA(Ribozyme)等方面的卓越贡献。最后简要地展望有机化学将对生物学发展作出进一步贡献的几个方面。     

吸附相反应技术用于不同载体表面纳米TiO2的制备

研究了不同载体对吸附相反应技术制备TiO2粒子的影响, 设计了两种不同表面形貌载体的温度实验(A型SiO2: 粒径20 nm, 比表面积640 m2·g-1; B型SiO2: 粒径12 nm, 比表面积200 m2·g-1), 并用电子能谱仪测定了两种载体表面TiO2含量随温度的变化. 结果表明, 两种载体表面Ti含量都随着温度的升高而减少, 且在一定温度范围内存在着突变, 但A载体突变的温度范围是40-60 ℃, 而B载体为30-50 ℃. TEM表征结果则显示, B表面TiO2粒子要比A表面的均匀. XRD得到的晶粒粒径曲线表明, A 载体表面TiO2晶粒粒径随着温度升高而减小并存在着突变, B载体表面粒子粒径则基本不变. 根据硅胶表面的吸附特性, 提出SiO2吸附的共性导致载体表面Ti含量变化曲线存在着共同点, 而载体内外表面的不同形貌则引起其表面吸附层的形貌以及温度敏感性不同, 最终导致两种载体表面Ti含量、晶粒粒径以及形貌上的差别.     

A Comparative Study of Electrochemical Reduction of 4‐Nitrophenyl Covalently Grafted on Gold and Carbon

4‐Nitrophenyl layers were grafted on gold and glassy carbon surfaces by electrochemical reductive adsorption of the corresponding diazonium salt. Electrochemical conversion efficiencies of 4‐nitrophenyl moieties to 4‐aminophenyl moieties on gold versus on glassy carbon in a protic medium were investigated using X‐ray photoelectron spectroscopy (XPS). In total contrast to all previous comparative studies showing greater electrochemical reactivity of aryl diazonium salt‐derived layers on gold than on glassy carbon, a much lower rate of conversion to 4‐aminophenyl was observed on gold than on glassy carbon by both cyclic voltammetry (CV) and chronoamperometry (CA) methods. The lower electron transfer rate during conversion observed on gold versus glassy carbon was proposed to be due to a mechanism related to the molecular structure rearrangement of 4‐nitrophenyl during the process on glassy carbon. However, whilst complete conversion of 4‐nitrophenyl to 4‐aminophenyl on gold by chronoamperometry was achieved, on glassy carbon complete reduction could not be achieved under the same conditions.     

钒胰岛素样作用研究进展

对钒酸盐的胰岛素作用的研究进行了综述，着重介绍了钒对糖尿病动物的降血糖作用及其机理的探讨。     

Ionic reaction of halogens with terminal alkenes: the effect of electron-withdrawing fluorine substituents on the bonding of halonium ions

Ionic reactions of terminal alkenes with chlorine (Cl(2)), bromine (Br(2)), and iodine monochloride (ICl) are sensitive to the alkyl substituents, and the positions and number of vinyl fluorine atoms. These perturbations influence the symmetry of the halonium ion intermediates, which can be determined by the distribution of the Markovnikov to anti-Markovnikov products. A vinyl fluorine on the number-2 carbon favors an unsymmetrical intermediate with greater charge on the number-2 carbon unless the alkyl group is electron withdrawing. A vinyl fluorine on the terminal number-1 carbon favors positive charge development on that carbon unless a resonance stabilizing group is on the number-2 carbon. The symmetry of halonium ions with vinyl fluorines on both carbons-1 and -2 depends primarily on the characteristics of the alkyl substituent. Intermediates range from open-ions with the positive charge on carbon-2, to various bridged species, to open-ions on the terminal carbon.     

阻光染料对氯化银乳剂光谱增感的影响

增感染料在卤化银微晶上吸附并形成J-聚集体是染料光谱增感和超增感的关键步骤.本文利用紫外-可见吸收光谱研究了增感染料和阻光染料在氯化银微晶上的吸附,并考察了阻光染料对增感染料J-聚集体的形成及乳剂感光性能的影响.结果表明:不同阻光染料在氯化银微晶表面的吸附程度不同,对增感染料J-聚集体形成的影响也有差异.其中,吸附较小的不影响增感染料J-聚集体的形成,而吸附较大的阻碍增感染料J-聚集形成,特别是阻光染料在增感染料之前加入乳剂中时.在氯化银微晶上吸附很小的阻光染料基本不影响增感染料对乳剂的光谱增感,而吸附较强的阻光染料不仅吸收入射光,还抑制或破坏增感染料的光谱增感.因此,在氯化银微晶表面没有吸附的阻光染料才是优良的阻光染料.     

CO oxidation on Pd(100) and Pd(111): a comparative study of reaction pathways and reactivity at low and medium coverages.

We have performed density functional theory calculations with the generalized gradient approximation to investigate CO oxidation on a close-packed transition metal surface, Pd(111), and a more open surface, Pd(100), aiming to shed light on surface structure effects on reaction pathways and reactivity, an important issue in catalysis. Reaction pathways on both surfaces at two different coverages have been studied. It is found that the reaction pathways on both surfaces possess crucial common features despite the fact that they have different surface symmetries. Having determined reaction barriers in these systems, we find that the reaction on Pd(111) is strongly coverage dependent. Surface coverages, however, have little effect on the reaction on Pd(100). Calculations also reveal that the low coverage reactions are structure sensitive while the medium coverage reactions are not. Detailed discussions on these results are given.     

不同取代基的噻碳菁和吲哚碳菁染料对其在溴化银微晶上吸附能力及形成J-聚集体尺寸分布的影响

本文研究了5-位不同取代基的噻碳菁和吲哚碳菁染料对其在立方型颗粒和T-颗粒溴化银微晶上吸附能力的影响,并采用ACFEM(Analytical Color Fluore scence Electron Microscopy)研究了上述结构染料对其吸附在溴化银微晶所形成的J-聚集体尺寸分布的影响。实验结果表明,对吲哚碳菁染料来说,立方体溴化银微晶表面的吸附能力较T-颗粒溴化银微晶表面的吸附能力强;但对噻碳菁染料来说则相反,它们在T-颗粒溴化银微晶表面的吸附能力较立方体溴化银微晶表面的吸附能力强。另外,对5-位不同取代基的噻碳菁染料而言,无论是在立方型颗粒或T-颗粒溴化银微晶上的吸附能力来说,含取代基(无论4-取代基是吸电子型还是推电子型)的噻碳菁染料较未取代的噻碳菁染料强;而5-位取代基是吸电子型的噻碳菁染料更有利于其吸附在T-颗粒溴化银微晶表面。此外,本文还进一步证明了溴化银微晶表面上染料J-聚集体的生长过程是符合奥斯瓦尔特成熟过程的。吲哚碳菁染料在T-颗粒溴化银微晶上形成的J-聚集体的平均尺寸明显大于在立方体溴化银微晶上形成的J-聚集体的平均尺寸。吸附在立方体溴化银微晶上的5-不同取代基的噻碳菁染料对其形成J-聚集体尺寸分布的影响的研究结果表明,含取代基(-CH₃,-Ph,-Cl)的噻碳菁染料形成的J-聚集体的尺寸分布几乎相同,但与未取代的噻碳菁染料形成的J-聚集体的尺寸分布明显不同;5-位含取代基的噻碳菁染料形成的J-聚集体平均尺寸大于未取代的噻碳菁染料的。