The photoelectron spectra of trimethylgermane,chloro- and fluoro-trimethylgermane

The He(I) photoelectron spectra of the series Mein3GeX (X = F, Cl, H) is reported. Assignments are proposed based on comparisons with spectra of similar compounds and on semi-empirical CNDO/2 calculations. The He(II) spectra were used to resolve some ambiguities.     

Wong-Zakai approximations for stochastic differential equations

The aim of this paper is to give a wide introduction to approximation concepts in the theory of stochastic differential equations. The paper is principally concerned with Zong-Zakai approximations. Our aim is to fill a gap in the literature caused by the complete lack of monographs on such approximation methods for stochastic differential equations; this will be the objective of the author's forthcoming book. First, we briefly review the currently-known approximation results for finite- and infinite-dimensional equations. Then the author's results are preceded by the introduction of two new forms of correction terms in infinite dimensions appearing in the Wong-Zakai approximations. Finally, these results are divided into four parts: for stochastic delay equations, for semilinear and nonlinear stochastic equations in abstract spaces, and for the Navier-Stokes equations. We emphasize in this paper results rather than proofs. Some applications are indicated.The author's research was partially supported by KBN grant No. 2 P301 052 03.     

Application of semi-permeable membrane dialysis/ion trap mass spectrometry technique to determine polybrominated diphenyl ethers and polychlorinated biphenyls in milk fat

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are hazardous food contaminants, their maximum legally allowable levels in food and environment are in the low pg g⁻¹ range. Therefore some highly selective and sensitive analytical methods must be used to determine them. The 96/23/EC Directive implemented by EC Decision of 12 August 2002 requires recovery rate of an analyte at a concentration below 1 ng g⁻¹ within the 50–120% range at relative standard deviation (RSD) as low as possible.     

Synthetic Routes to α-Aminoacids Derivatives. Part I. Carbomethoxylation of Metalated N-Nitrosoamines

N-nitrosoamines are well known to undergo α-metalation when treated with appropriate strong bases^1,2.     

Wheat as a feedstock for fuel ethanol

Applied Biochemistry and Biotechnology - Canadian Prairie Spring and Soft White Spring wheats, which contained high levels of starch, gave higher concentrations of ethanol after fermentation than...     

Recent Developments in Spectrophotometric Methods for Determination of Vanadium

Owing to the toxic and essential nature of vanadium in biological systems, there has been considerable interest in the determination of its content in different kinds of samples. Among several analytical techniques for the determination of vanadium, spectrophotometric methods are very popular due to their simplicity and low-cost instrumentation. Various attempts have been made to modify these methods in order to improve their sensitivity and selectivity. This review shows recent developments in the spectrophotometric determination of vanadium and highlights those which can be used for speciation analysis of this element.     

Experimental matrix isolation study and quantum-mechanics-based normal-coordinate analysis of the anharmonic infrared spectrum of picolinic acid N-oxide

This work is, according to our knowledge, the first experimental matrix isolation study of a molecular system with a very short and strong intramolecular OH...O hydrogen bond. It also includes a satisfying interpretation of its entire infrared spectrum. The interpretation relies on the calculation at the DFT/B3LYP/6-31G(d,p) level of the harmonic spectrum and of the anharmonic relaxed potential energy for the stretching motion of the hydrogen-bonded proton, used with our recently modified quantum-mechanics-based normal-coordinate analysis. An important observation about the anharmonic spectrum obtained from this procedure is that the OH stretch coordinate contributes to several normal modes, mixing extensively with other in-plane internal coordinates, in particular OH-bending and C=O-stretching. The two intense normal modes with the largest contributions from the OH-stretching coordinate to the potential energy distribution and to the intensity are located near 1700 and 1500 cm(-1). A calculated anharmonic spectrum obtained from this procedure agrees with the experimental spectrum (frequencies and intensity distribution), within the limits of the estimated uncertainties for the calculation and experiment, allowing the interpretation of the latter. The agreement for the frequencies is about 1-3%. The anharmonic spectrum calculated using the anharmonic keyword in Gaussian 03w is not in satisfactory agreement with experiment insofar as the OH-stretching mode is concerned.     

The sequential generation of random edge maximalf-graphs as a function off

A graph with no vertex of degree greater thanf is called anf-graph. Anf-graph to which no edge can be added without introducing a vertex of degree greater thanf is called anedge maximal f-graph. We consider the following procedure. Starting withn labeled vertices and no edges, sequentially add edges one at a time so as to obtain at each step a labeledf-graph. At each step, the edge to be added is selected with equal probability from among those edges whose addition would not violate thef-degree restriction. A terminal graph of this procedure is asequentially generated random edge maximalf-graph. LetP(m; n; f) denote the probability that a sequentially generated random edge maximalf-graph of ordern hasm vertices of degree less thanf. The determination of the distributionP(m; n; f) is an open problem posed by P. Erds. We have obtained various insights concerningP(m; n; f). In particular, we conjecture the form ofP(m; n; f) as a function off.     

The chemistry of thujone. VIII. Thujone as a chiral synthon for the synthesis of optically active steroid analogues. The enol lactone route

The thujone-derived enone 1 is converted via enol lactone intermediates 4 and 5 to the optically active steroidal analogue 13 and the corresponding 19-norsteroid analogue 14 . The structure of 13 was determined by X-ray diffraction analysis. The acid-catalyzed cyclopropane-ring opening of 13 and ozonolysis of the resulting olefin provided the 16-keto-steroid analogue 18 .