Infrared and Raman spectral interpretations of the ferroelectric phases of NaH3(SeO3)2 and NaD3(SeO3)2

The infrared and Raman spectra of NaH₃(SeO₃)₂ and NaD₃(SeO₃)₂ have been recorded from 24 to 300°K. The interpretation, assignments, and analysis of the spectral studies are presented on the paraelectric α phase (proton disordered), ferroelectric β phase (proton ordered) and ferroelectric γ phase (proton ordered). A discussion of a newly proposed proton-triggered phase transition mechanism and a possible origin of the hydrogen-bonded OH stretching region of KH₂PO₄-type ferroelectrics is given.     

Übergangsmetallkomplexe mit Anionen von 1-substituierten 1,2,3,4-Tetrazolin-5-onen und -thionen und von 1,3-Thiazolin-2-thion

Transition Metal Complexes with Anions of 1-substituted Tetrazolinones and -thiones and of 1,3-Thiazolin-2-thione The preparation of a series of anionic and phosphine containing complexes with the ambivalent anions of 1-R-tetrazolin-5-ones and -5-thiones, and of 1,3-thiazolin-2-thione is reported. According to the i.r. and ¹H n.m.r. spectra the S-heterocycles are bonded through the exocyclic sulfur atom to the metal; in the oxotetrazolinate compounds coordination occurs via the N² or N⁴ ring atoms. The copper and silver complexes [(Ph₃P)MX]₂ (X = anionic heterocycle) have been found to be dimeric.     

Rapid polarographic method for determining arsenic in steel

A simple and sensitive polarographic method for determining arsenic in steel is presented. The steel is dissolved in HNO(3), and arsenic reduced with Na(2)S(2)O(5)-K.I. The polarographic wave is recorded for an electrolyte at pH 3.0 and containing Fe(II), Mn(II). citric and ascorbic acids. Levels of 0.2% and 0.003% As can be determined with a coefficient of variation of +/- 6%.     

Gas chromatographic confirmation of amino acid structure via diastereomer preparation.

The partial gas chromatographic (GC) resolution of several amino acid N-trifluoroacetyl 2-butyl ester diastereomeric derivatives on a short packed column has been used to confirm GC peak assignments in analysis of a marine sediment sample.     

Rasche S?ulentrennungen unter Verwendung eines oberfl?chlich sulfonierten Harzaustauschers

Zusammenfassung Die Verwendung oberflächlich sulfonierter Harzaustauscher hat die wesentlichen Vorteile, daß die Trennung sehr rasch und mit sehr verdünnten Elutionsmitteln erfolgen kann. Dies wird am Beispiel der Trennungen Na/Cs, Cs/Sr, Cs/Y, Ba/Cs und Sr/Y erläutert.

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Rapid column separations by means of a superficially sulphonated exchange resin

The use of superficially sulphonated ion-exchange resins has the essential advantages that the separations can be achieved very fast and with dilute eluents. Some examples of column separations (Na/Cs, Cs/Sr, Cs/Y, Ba/Cs, and Sr/Y) confirm this result.

     

Separation of actinides from Low Level Liquid Wastes (LLLW) by extraction chromatography using novel DMDOHEMA and TODGA impregnated resins

The uptake of several actinides [U(VI), Th(IV), Am(III), Cm(III)] and fission products was investigated from nitric acid solutions by two novel extraction chromatographic sorbents containing 2-(2-hexyloxy-ethyl)-N,N'-dimethyl-N,N'-dioctyl-malonamide (DMDOHEMA) and N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide (TODGA), respectively. The kinetics of the uptake of actinides was studied. The sorption of metal ions fromz simulated Low Level Liquid Waste (LLLW) solutions was evaluated. The results of these experiments revealed that the actinides and lanthanides could be separated from the bulk of other fission products in simulated LLLW solutions on both sorbents.This revised version was published online in November 2005 with corrections to the Cover Date.     

Mutagenesis approaches to deduce structure-function relationships in terpene synthases

This review highlights mutagenesis studies of terpene synthases, specifically sesquiterpene synthases and oxidosqualene cyclases. Mutagenesis studies of these enzymes have provided mechanistic insights, structure-function relationships for specific enzymatic residues, novel terpene structures and enzymes with novel activities. The literature through 2002 is reviewed and 113 references cited.     

A Study of the Encapsulation of Nickel Phthalocyanine in Molecular Sieve Zeolites of the FAU Type

Nickel(II)phthalocyaninate spectroscopy (NiPc) was synthesized in the supercages of zeolite FAU by the template synthesis method at two different temperatures of 200 and 300°C and characterized by diffuse reflectance spectroscopy, UV-Vis spectroscopy, X-ray powder diffraction, and IR. The results show that the catalyst synthesized at 200°C contains a higher amount of complex as monomeric species encapsulated in the supercages. At elevated temperature, higher amount of the NiPc may be hosted in the mesopores and/or on the external surface of the zeolite as aggregates.     

Fractionation and Determination of Different Lead Species in Contaminated Soils

A new approach was proposed to fractionating soil lead species differing in mobility and biological availability. Ground solid samples were retained as a stationary phase in a rotating coiled column while continuously pumping aqueous solutions of salts and complexing agents necessary for the sequential leaching of different element species. It was shown that field-flow fractionation in a rotating coiled column is suitable for separating three lead species in an automatic mode within 4 h, as compared to several days for conventional methods of sequential extraction. The study of lead elution curves at different fractionation steps provides additional information about its mobilization under changing environmental conditions.     

Trace anion determination in concentrated hydrofluoric acid solutions by two-dimensional ion chromatography II. Method performance study with a hydroxide eluent and a low noise suppressor

The two-dimensional ion exclusion chromatography/ion chromatography (ICE-IC) approach is considered to be the method of choice for the determination of trace anions in concentrated hydrofluoric acid (48-50%, w/w). In order to achieve lower detection limits, this method was for the first time used with electrolytically generated and purified hydroxide eluents in combination with a low noise electrochemical suppressor. Compared to carbonate based eluents, the achieved gain in peak height sensitivity for chloride, sulfate, nitrate and phosphate is a factor of 6, 7, 16 and 13, respectively. The instrumental detection limits, based on the background noise, are 2, 0.2, 0.4 and 1.4 microg/kg HF 50% (w/w) for the same anions. Their method detection limits, calculated according to SEMI, are all within the 6-10microg/kg HF 50% (w/w) range and thus at least 10 times lower than the current Tier C grade requirements. The chromatographic run time could be shortened with some 10 min by the use of a relatively fast high-capacity hydroxide selective anion exchange column.