Measuring ambient radon using a scintillating optical fiber bundle

A new method for detecting and measuring radon and its radioactive progeny is described, involving a bundle of scintillating optical fibers. The general sensor construction is described. A preliminary field trial is described in which the fiber sensor responded in a comparable way with a commercial radon measurement instrument, to varying ambient radon levels.     

Elemental speciation by chromatographic separation with inductively coupled plasma mass spectrometry detection

Separation techniques coupled to inductively coupled plasma mass spectrometry (ICP-MS) is reviewed. ICP-MS technique is described briefly. Coupling of the different separation techniques are described, together with the most common applications used for each technique that has been described in the literature. An overview for the future of separation techniques coupled to ICP-MS with regard to elemental speciation is discussed.     

Pd-catalyzed regio and stereocontrolled mono and bis-coupling reactions of 1-bromo-6-chlorohexa-1,3,5-triene: synthesis of a naturally occurring tetraenynone

The synthesis of new 1,6-dihalogenohexatrienes is described. The chemoselectivity of pallado-catalyzed cross-coupling reaction is studied and a short synthesis, by Negishi and Sonogashira reactions, of a natural product is described.     

Model investigations of network-forming materials

Recent advances in the study of network-forming materials are described for systems dominated both by ionic and covalent interatomic interactions. Modelling strategies are described which focus both on describing specific systems of interest and on modelling the systematic evolution of network topology. The effect of network topology on the presence of ordering both on intermediate- and extended-length-scales is discussed. The effect of the topology on the mechanical rigidity is also described and analysed in terms of a mean coordination model. In addition, the isomorphology between amorphous silicon and the silicon sub-lattice in SiO(2) is described. Polyamorphism in Si and ZnCl(2) is analysed and discussed. Finally, the study of reduced (two) dimensional systems is discussed for carbon, silicon and germanium.     

Synthesis and conformational behavior of e-3,4-diethyl-2,2,5,5-tetramethylhexene-31)

Synthesis of 2 is described by reductive coupling of 1; the temperature dependent ¹H-NMR-spectrum can be described by the interconversion of the two preferred conformations 2a and 2b (ΔG₃₀₀3= 18.3 kcal/mole), which is qualitatively described by force-field calculations.     

Efficient microwave combinatorial parallel and nonparallel synthesis of N-alkylated glycine methyl esters as peptide building blocks

An easy and convenient microwave-assisted synthesis of N-alkylated glycine methyl esters is described. Parallel and nonparallel combinatorial methods are described and compared. The described reactions are reductive alkylations of several aldehydes and glycine methyl ester in the presence of NaBH3CN. Good yields and short reaction times are the main aspects of these procedures.     

Inherent structures of crystalline tetracene

We have systematically sampled the potential energy surface of crystalline tetracene to identify its local minima. These minima represent all possible stable configurations and constitute the "inherent structures" of the system. The crystal is described in terms of rigid molecules with Coulombic and atom-atom interactions. Hundreds of distinct minima are identified, mostly belonging to the space groups P (triclinic) and P2(1)/c (monoclinic), with a variety of structural arrangements. The deepest minimum corresponds to the high temperature-low pressure polymorph. This is the only polymorph with a completely described X-ray structure, which is satisfactorily described by the calculations. The next deep minimum is likely to correspond to the low temperature-high pressure polymorph, which has been experimentally identified but not yet fully described.     

A one-pot method for the synthesis of 2-aminobenzimidazoles and related heterocycles

A rapid and efficient one-pot method for the synthesis of 2-aminobenzimidazoles and related heterocycles is described. The reaction is mediated by a polymer-supported carbodiimide, which simplifies product isolation. The scope and limitations of this method are described.     

Synthesis and mass spectra of 1-arylideneamino-1,2,3-triazoles

The synthesis of the title Compounds is described. Their mass spectra upon electron impact are given and the main fragmentation pathways are described.     

Formation of particles of metal hydroxides in water solution of polymer

The stages of the formation of metal hydroxide particles in water medium were described. The first stage is the formation of complexes between the stabilizer and metal ion or of metal polyions containing a few metal ions. Dependence between the number of metal ions in polyion and its charge on the pH is described. The second stage is the formation of the metal hydroxide particles by the aggregation of polyions or their adsorption on/in the stabilizer. The distribution of the polyion number in the particles in polyion aggregation is described by the equation p(k) = k(ks-1)(k-1)/ksk and in polyion adsorption on/in the stabilizer particles is more narrow and is described by the equation p(k) = exp(-ks)/ks(-k)/k!, where k and ks are the number and the average number of polyions in the particle.     

Preparation of hollow beads of poly(styrene-co-divinyl benzene)

Two methods are described for the production of hollow beads by copolymerization of styrene and divinyl benzene. Characterization of the beads is described and growth mechanisms proposed.     

Synthesis of nucleoside 3′,5′-cyclic phosphorothioates

A convenient and general method for the synthesis of nucleoside 3′,5′-cyclic phosphorothioates using nucleosides as starting materials is described.A synthesis of nucleoside 3′,5′-cyclic phosphorothioates is described.     

Synthesis, characterisation and high-performance liquid chromatography of C6-C16 dicarboxylyl-mono-coenzyme A and -mono-carnitine esters.

The synthesis and purification of the mono-coenzyme A and mono-carnitine esters of the homologous series of straight-chain even-numbered dicarboxylic acids (C6-C16) is described. The corresponding 3-hydroxyacyl- and 2-enoyl-CoA esters were prepared enzymatically. A reversed-phase high-performance liquid chromatographic (HPLC) system for the analysis of the intact CoA esters is described and their chromatographic behaviour documented. Reversed-phase HPLC systems for the analysis of the 4-bromophenacyl derivatives of the dicarboxylyl-mono-carnitines and the 4-nitrobenzyl derivatives of the free acids are also described. Some preliminary studies of the metabolism of [U-14C]hexadecanedionoyl-mono-CoA by rat liver peroxisomes and rat skeletal muscle mitochondria are described illustrating the application of these methods.     

High-performance liquid chromatographic assay of betamethasone 17-valerate and its degradation products

A high-performance liquid chromatographic assay of betamethasone 17-valerate is described. The procedure may be use for quantitative assay of the degradation products, betamethasone 21-valerate and betamethasone, and the application to the analysis of ointments is described. The method is also suitable for the determination of the kinetics of decomposition from one experimental run, and the determination of rate constants from a four-compartment sequential reaction is described. The procedure is also applicable to other corticosteroids, and hydrocortisone 17-butyrate, hydrocortisone 21-butyrate, and hydrocortisone may similarly be determined without modification to the method.     

Multipole expansions of orbital products about an intermediate center

A numerical method described previously (Talman, Int J Quantum Chem, 2007, 107, 1578) is reviewed and a modified formulation that may be more computationally efficient is presented. Modifications required for the application to real harmonics are described. The method requires the numerical evaluation of a one‐dimensional integral on a finite interval, and an improved method for this is described. The application to the evaluation of electron–electron repulsion four‐center integrals is also discussed. It is indicated that μ H accuracy is obtainable with modest computational effort. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

A convergent total synthesis of epolactaene: an application of the bridgehead oxiranyl anion strategy

The generation and reaction of a lactone-derived oxiranyl anion is described. The aldol-type reaction of the epoxylactone and aldehydes was accomplished by a two-step procedure via the trimethylsilyl epoxylactone. The application of this methodology to the total synthesis of (+)-epolactaene and its analogs is described.     

Development of a [3+3] approach to tetrahydropyridines and its application in indolizidine alkaloid synthesis

A stepwise [3+3] annelation sequence is described that generates tetrahydropyridines from the corresponding aziridines. The scope of this process is described and its potential for the stereoselective synthesis of indolizidines is highlighted by the synthesis of (−)-monomorine.     

Application of gas-liquid chromatography for standardization of herbal raw materials and herbal drugs

Gas chromatography with mass selective detection is described as method for investigation and standardization of herbal raw materials and herbal drugs. Marker compounds and chromatographic conditions are described for some herbs.     

Synthesis and nucleophilic substitutions of 3-alkyl-5-chloroisoxazoles

A 3-alkyl-5-chloroisoxazole synthesis is described based on the cycloaddition of nitrile oxides to 1,1-dichloroethylene, an inexpensive dipolarophile. Substitution of the chloride in these adducts by various nucleophiles is also described.     

Preparation of chiral indenes containing β-pinenyl derived ligand substituents

A simple procedure for the preparation of new 1-, 2- and 1,3-chirally substituted indenes is described in which indenyllithium or 2-indenylmagnesium bromide is reacted with a β-pinenyl derived chlorosilane. Synthesis of the ethylene bridged bis(indene) analogues of two of the new compounds is also described.