Behaviour of Mo,Al, As,Cs, Sn,Sb, Pd,Rh, Ru,Ge, Se and Te on the macroporous resin AG MP-1 in alkaline medium

The behaviour of Mo and some other elements on Ag MP-1 in alkaline medium was investigated. Equilibrium distribution coefficients, K_d, are presented for Mo on the anion exchangers AG 1-X2, AG 1-X4, AG 1-X8 and AG MP-1, and for some elements on AG MP-1 in alkaline medium. An anion exchange chromatographic separation of Mo from some of these elements is described and some results obtained with this method are reported.     

Magnetic nanoparticles: Synthesis, stabilization, functionalization, characterization, and applications

This review focuses on the synthesis, protection, functionalization, characterization and with some applications of magnetic nanoparticles (MNPs). The review begins with an overview on magnetic property and single domain particles. The synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the synthesis of monodisperse samples of relatively large quantities are also discussed. Then, different methodologies for the protection and functionalization of the synthesized MNPs, together with the characterization techniques are explained. Finally, some of the recent industrial, biological, environmental and analyticals application of MNPs are briefly reviewed, and some future trends and perspectives in these research areas will be outlined.     

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.     

Photoinduced activation of molecular oxygen by various porphyrins,bis-porphyrins,phthalocyanines, pyridinoporphyrazins,and their metal derivatives

Aerobic irradiation of tetraphenylporphyrins, phthalocyanines, tetra-t-butylphthalocyanines, tetracarboxylphthalocyanines, tetrapyridinoporphyrazins and some of their metal derivatives with visible light (λ > 420 nm) give singlet oxygen by energy transfer and oxygen superoxide by electron transfer, but some of their Cu, Zn of Pt derivatives are efficient quenchers for superoxide formation.     

The electrostatic molecular potential for imidazole,pyrazole, oxazole and isoxazole

The electrostatic molecular potentials arising from ab initio MO LCAO GTO SCF wavefunctions for some five membered heterocycles are used to make evident differences in reactivity of some sites (tertiary nitrogen, carbon atoms) towards electrophilic reagents. Results are in general accordance with experiment.     

High temperature superconductors: Theory,developments, perspectives

With the discovery of the high-temperature superconductors, interest has grown enormously in this new class of ceramic compounds. Here we review their structure, preparation and physical properties as well as some aspects which are important for possible applications. Chemical bonding is described and some considerations on the possible mechanism of superconductivity are mentioned. A brief perspective of possible technologies is given.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Thermal studies on lithium,sodium, potassium and ammonium monomethyl violurates

A study of the ammonium and some alkaline salts of monomethyl violuric acid by TG and DSC is described. These salts form hydrates in all cases and are, with some exceptions, very soluble in water.     

The determination of cadmium,copper, iron,lead and zinc in aerosols by atomic-absorption spectrometry

The determination of five elements in filter papers loaded with air particulate matter has been investigated. After a wet destruction of about 10 cm² of filter material by a standard procedure, analysis was carried out with a flame atomic absorption method for zinc and a flameless procedure for Cd, Cu, Fe and Pb. Furnace program parameters for each of the elements in different acid solutions are reported. The interferences of some common anions and the most abundant cations in aerosol material are described. For some urban and industrial samples, the results are compared with those obtained by energy-dispersive x-ray fluorescence. Accuracy was checked against standard samples.     

Inorgranic Reaction Mechanisms,Volume 3 (A Specialist Periodical Report of the Chemical Society,London), J. Burgess,Senior Editor,The Chemical Society,London, 1974, xvii + 500 pages, ß14.00.

A polyphosphite obtained from poly(methallyl alcohol), when treated with rhodium(I) derivatives, affords soluble and insoluble complexes, some of which are hydrogenation catalysts for olefins in toluene suspension.     

Multistage reactions,equilibrium, and detailed balancing: A linear algebra approach

Methods of linear algebra are applied to (a) the problem of determining whether detailed balancing for some or all stages of a chemical process is implicit from the existence of steady state for some or all of the chemical species involved, and (b) the formulation of general concentration-type equilibrium relationships solely from kinetic considerations and the assumption of full detailed balancing.     

Electronic structure and bonding of the 3d transition metal borides, MB, M=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu through all electron ab initio calculations

The electronic structure and bonding of the ground and some low-lying states of all first row transition metal borides (MB), ScB, TiB, VB, CrB, MnB, FeB, CoB, NiB, and CuB have been studied by multireference configuration interaction (MRCI) methods employing a correlation consistent basis set of quintuple cardinality (5Z). It should be stressed that for all the above nine molecules, experimental results are essentially absent, whereas with the exception of ScB and CuB the remaining seven species are studied theoretically for the first time. We have constructed full potential energy curves at the MRCI/5Z level for a total of 27 low-lying states, subsequently used to extract binding energies, spectroscopic parameters, and bonding schemes. In addition, some 20 or more states for every MB species have been examined at the MRCI/4Z level of theory. The ground state symmetries and corresponding binding energies (in kcal/mol) are 5Sigma-(ScB), 76; 6Delta(TiB), 65; 7Sigma+(VB), 55; 6Sigma+(CrB), 31; 5Pi(MnB), 20; 4Sigma-(FeB), 54; 3Delta(CoB), 66; 2Sigma+(NiB), 79; and 1Sigma+(CuB), 49.     

[N,N-二-(2-氯乙基)]-O-[O′,O′-二烷基膦酰甲基]-N′,N′-二烷基磷酰二胺的合成及性质研究

合成了6种含有氮芥结构及膦酰甲基取代基的磷酰二胺。其结构经~1H NMR、MS和元素分析确定,讨论了它们的性质,并对部分化合物的抗癌活性进行了初步试验。     

Heterogeneous catalysis: enigmas, illusions, challenges, realities, and emergent strategies of design

Predominantly this article deals with the question of how to design new solid catalysts for a variety of industrial and laboratory-orientated purposes. A generally applicable strategy, illustrated by numerous examples, is made possible based on the use of nanoporous materials on to the (high-area) inner surfaces of which well-defined (experimentally and computationally) active centers are placed in a spatially separated fashion. Such single-site catalysts, which have much in common with metal-centered homogenous catalysts and enzymes, enable a wide range of new catalysts to be designed for a variety of selective oxidations, hydrogenations, hydrations and hydrodewaxing, and other reactions that the "greening" of industrial processes demand. Examples are given of new shape-selective, regio-selective, and enantioselective catalysts, many of which operate under mild, environmentally benign conditions. Also considered are some of the reasons why detailed studies of adsorption and stoichiometric reactions at single-crystal surfaces have, disappointingly, not hitherto paved the way to the design and production of many new heterogeneous catalysts. Recent work of a theoretical and high-throughout nature, allied to some experimental studies of well-chosen model systems, holds promise for the identification of new catalysts for simple, but industrially important reactions.     

Density-functional and electron correlated study of five linear birefringences--Kerr, Cotton-Mouton, Buckingham, Jones, and magnetoelectric--in gaseous benzene

We present the results of an extended study of five birefringences--Kerr, Cotton-Mouton, Buckingham, Jones, and Magnetoelectric--on benzene in the gas phase. The relevant molecular quantities--first-order properties, linear, quadratic, and cubic response functions--are computed employing the density-functional theory (DFT) response theory, with a choice of functionals. In some cases, different functionals are employed for the wave-function computational step and for the subsequent analytical response calculation to determine the combination yielding at the same time the optimal energy and energy derivative results. Augmented correlation consistent basis sets of double and triple zeta quality are used. The DFT results are compared to those obtained at the Hartree-Fock level and in some cases within a coupled cluster singles and doubles electronic structure model. The study tries to assess the ability of the DFT response theory to describe a wide range of properties in a system of rather large size and high complexity. The relative strength of the five birefringences for plausible experimental conditions is determined and, when possible, comparison is made with the results of the measurements.     

Spontaneous resolution, whence and whither: from enantiomorphic solids to chiral liquid crystals, monolayers and macro- and supra-molecular polymers and assemblies

One of the great challenges in stereochemistry is the explanation of why some molecules resolve spontaneously while others do not. In this critical review the recent advances in the creation of chiral systems from achiral and racemic compounds in three-, two- and one-dimensional systems are discussed. There are some groups of molecules in some systems that do tend to display conglomerates, which may suggest that there are enantiophobic and enantiophilic molecules whose assembly is guided by the structural and thermodynamic properties of the systems in question.     

Palladium assisted organic reactions: III. The preparation of di-μ-chlorobis-(N,N-dialkylbenzylamine-2,C,N)dipalladium(II) complexes

The preparation and ¹H NMR spectra of some di-μ-chloro-bis(N,N-dialkylbenzylamine-2,C,N)dipalladium(II) complexes, and the corresponding monomeric triphenylphosphine derivatives are described. A reaction sequence is presented for the cyclopalladation reaction and some improved conditions for the preparation of these complexes are presented.     

Comparison of olive,corn, soybean and sunflower oils by PDSC

Vegetable oils of different types and qualities are widely used in homemade cooking and food industry. Most of the safety concerns were related to possible oxidation processes produced at the relatively high temperatures used when frying. Thus, the thermal stability to oxidation is an important parameter for edible oils. Oils from the Arbequina, Picual, Hojiblanca and Cornicabra olive varieties, corn, soybean and sunflower are studied in this work by means of pressure differential scanning calorimetry (PDSC). The general aim of this work is to evaluate the thermooxidative stability of these vegetable oils by the ASTM onset oxidation temperature (OOT) method. In addition, the ability of some parameters to identify different oils and some relations between the chemical composition and the OOT results are investigated.     

Synthesis,reactivity, and polymerization of vinylureas

The syntheses of N,N′-divinylureas and some related compounds are reported. Polymerization of these monomers and determination of the structures of the resulting polymers are described. Evidence is presented which supports the tendency of vinylureas to react through their tautomeric form.     

Errors,PGAA, and metrology

Analytical chemists are scientific scavengers, using any available physical phenomenon to determine the composition of materials. Accuracy, unlike mere reproducibility, depends on understanding the measurement process, most usefully by stressing it until it bends. The use of neutron capture gamma rays for analysis involves some issues not encountered in conventional neutron activation analysis which, when understood, extend the utility and reinforce the value of nuclear methods of elemental analysis. These methods are being increasingly recognized as tools for SI-traceable metrology.     

全反射X射线荧光光谱法同时测定地气样品中锰、镍、铜、锌、铅、铷和锶

论述了利用自行研制的有３个反射体的全反射分析装置，用钼靶Ｘ光管激发，以Ｓｅ为内标，同时测定了地气样品中Ｍｎ、Ｎｉ、Ｃｕ、Ｚｎ、Ｐｂ、Ｒｂ和Ｓｒ等元素。对纳克级元素含量，方法的精密度为７．２％．绝对检出限为１０－１０～１０－１１。其分析结果的准确度与无火焰原子吸收相符。