Self-chemical ionization of diethylzinc

The self-chemical ionization of diethylzinc is examined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and semiempirical molecular orbital calculations. Electron impact of diethylzinc neutral produces the radical cation, C(4)H(15)Zn(+) (m/z x 122), which reacts further with the neutral (C(2)H(5))(2)Zn to give the following product ions: Zn(+) (m/z x 64), C(2)H(5)Zn(+) (m/z x 93), C(4)H(9)Zn(+) (m/z x 121), C(4)H(11)Zn(2)(+) (m/z x 187), and C(6)H(15)Zn(2)(+) (m/z x 215). To determine the structure and pathways for production of these ions, monoisotopic (12)C(4)H(15)(64)Zn(+), (64)Zn(+) and (12)C(2)H(5)(64)Zn(+) were individually isolated and reacted with the neutral background. We also performed semiempirical molecular orbital calculations (ZINDO/1). The molecular orbital calculations and experimental data are consistent in predicting that the ethyl group on the diethylzinc cation carries the positive charge. Copyright 1999 John Wiley & Sons, Ltd.     

Crystal structure of bis(p-phenoxyphenyl) tellurium dichloride

Crystals of (p-PhOC₆H₄)₂TeCl₂ are monoclinic with space groupP2₁/c,a=8.063(2),b=21.695(5),c=12.622(2) Å,=101.57(2)°, andZ=4. The structure refined to a finalR value of 0.055 for 2135 unique observed reflections. The compound adopts a primary four-coordinate geometry based on a distorted trigonal bipyramid with an equatorial lone pair. A weak Te-Cl secondary interaction links the molecules into centrosymmetric dimers.     

The use of ion-exchange filters for the determination of iodide in milk by X-ray fluorescence spectrometry

An X-ray fluorescence spectrometric method has been developed for the quantitative determination of iodide in milk which makes use of anion-exchange filters for the isolation and concentration of iodide from the liquid samples. The milk is deproteinized with trichloroacetic acid, filtered then passed through an anion-exchange paper disc to remove the iodide. The disc is removed, dried then analysed by X-ray fluorescence spectrometry. Six samples, consisting of homogenized, 2% fat and skim milk were analysed and found to contain between 0.37-0.67 ppm iodide. Detection limits in milk were estimated to be 0.05 ppm.     

Exploring binding properties of gliclazide with human serum albumin

Journal of Thermal Analysis and Calorimetry - The thermodynamic parameters of the binding of gliclazide (GL) with human serum albumin (HSA) have been discussed along with the insight into the...     

Lead Tetraacetate Fragmentation of Loganin Aglucone O-Metheyl Ether and its Stereoisomers

During the investigation into methods of converting loganin (1) into secologanin (2, R=β-D-glucose), the lead tetraacetate fragmentation reaction¹ of the four diastereomeric loganin aglucone O-methyl ethers 4, 6, 9, and 11, was studied.     

Maximum norm a posteriori error estimate for a 3d singularly perturbed semilinear reaction-diffusion problem

A singularly perturbed semilinear reaction-diffusion problem in the unit cube, is discretized on arbitrary nonuniform tensor-product meshes. We establish a second-order maximum norm a posteriori error estimate that holds true uniformly in the small diffusion parameter. No mesh aspect ratio condition is imposed. This result is obtained by combining (i) sharp bounds on the Green’s function of the continuous differential operator in the Sobolev W ^1,1 and W ^2,1 norms and (ii) a special representation of the residual in terms of an arbitrary current mesh and the current computed solution. Numerical results on a priori chosen meshes are presented that support our theoretical estimate.