The effect of rock type,grain size,sorting, permeability,and moisture on measurements of radon in soil gas: A comparison of two measurement techniques

Soil surveys of radon conducted in the Coastal Plain of New Jersey, Alabama and Texas indicate that soil composition and grain size exert the strongest control on the concentration of radon measured. Soil-gas radon was measured in-situ using two techniques; one developed by G. Michael REIMER of the U. S. Geological Survey; the other developed by Rogers and Associates Engineering Corp. for use by the Environmental Protection Agency. The Reimer technique aquires a small-volume, grab sample of soil gas, whereas the Rogers and Associatess technique acquires a large-volume, flow-through sample of soil gas. The two techniques yield similar radon concentrations in well-sorted sands, but do not correlate as well for poorly sorted soils and clays.     

Molecular Structure of Triphenylamine in the Gas Phase

The molecular structure of triphenylamine was studied by gas-phase electron diffraction in combination with ab initio calculations. It is found that in the gas phase at 160°C the molecule possesses C₃ symmetry. The principal geometric parameters are as follows (r _a structure): N-C 1.421(4), C-C_mean 1.399(1), C-H 1.123(2) Å, bond angles NCC 123.6(10)° and 117.2(7)°, and CNC 119.9(2)°. Torsion angles around C-N bonds are ?39° and ?45°. Phenyl groups are rotated by 48° from the position in which the C₃ axis lies in the phenyl ring plane.     

The Strength of Cartan's Version of Nevanlinna Theory

In 1933 Henri Cartan proved a fundamental theorem in Nevanlinnatheory, namely a generalization of Nevanlinna's second fundamentaltheorem. Cartan's theorem works very well for certain kindsof problems. Unfortunately, it seems that Cartan's theorem,its proof, and its usefulness, are not as widely known as theydeserve to be. To help give wider exposure to Cartan's theorem,the simple and general forms of the theorem are stated here.A proof of the general form is given, as well as several applicationsof the theorem. 2000 Mathematics Subject Classification 30D35.     

Synthesis of 8-Halopurines by Reaction of Lithiated Purines with Appropriate Halogen Donors

Purines lithiated in the 8-position, can be trapped with hexachloroethane, dibromotetrachloroethane, cyanogen bromide and cyanogen iodide, to give a variety of 8-halopurines in excellent yields.     

Determination of 8‐epi PGF2α concentrations as a biomarker of oxidative stress using triple‐stage liquid chromatography/tandem mass spectrometry

F2‐isoprostanes are a family of prostaglandin F2‐like compounds that are formed by free‐radical‐catalyzed peroxidation of arachidonic acid. Several F2‐isoprostanes, but in particular 8‐epi PGF_2α, are widely used as oxidative stress biomarkers. An analytical method based on liquid chromatography with negative electrospray ionization (ESI) coupled to tandem mass spectrometric detection (LC/MS/MS) was developed for the determination of 8‐epi PGF_2α concentrations in human plasma, whole blood, erythrocytes and urine. 8‐epi PGF_2α‐d4, a stable isotope derivative of 8‐epi PGF_2α, was used as an internal standard (IS). A 50 µL sample was focused on‐column and separated on two 3 µm particle size SUPELCOSIL? ABZ+Plus HPLC columns (15 cm × 4.6 mm and 7.5 cm × 4.6 mm) connected in series. An Applied Biosystems 4000 Q TRAP LC/MS/MS system with ESI was operated in multiple reaction monitoring (MRM) mode with the precursor‐to‐product ion transitions m/z 353.4 → 193.1 (8‐epi PGF_2α), 357.4 → 197.1 (8‐epi PGF_2α‐d4), used for quantification. The assay was fully validated and found to have adequate accuracy, precision, linearity, sensitivity and selectivity. The mass limit of detection (mLOD) was 1 pg of analyte eluting from the column. The assay has been successfully applied to the analysis of human plasma, whole blood, erythrocytes and urine samples. Copyright © 2009 John Wiley & Sons, Ltd.     

Calculated tautomeric equilibria and X-ray structures of 2-substituted N-methoxy-9-methyl-9H-purin-6-amines

Density Functional Theory calculations of nine 2-substituted N-methoxy-9-methyl-9H-purin-6-amines in the amino and imino tautomeric forms, as well as the complexes of the same with dimethyl sulfoxide (DMSO), were performed using two functionals (BP86 and B3LYP) and two basis sets (SV(P) and def2-TZVP). Solid-state structures of two of the compounds were obtained from single-crystal X-ray diffraction techniques. It was found that the inclusion of both an explicit hydrogen-bonding partner (DMSO) as well as continuum solvation effects, and vibrational corrections to energy, were necessary for qualitative and reasonable quantitative agreement with observed tautomeric ratios. The solution-optimized geometries and X-ray structures were found to be in good agreement. NMR spectroscopy confirmed the dependence of the tautomeric ratios on hydrogen-bonding abilities, in addition to the dipole moment of the solvent in question. Natural Bond Orbital charges on the N-7 nitrogen, as well as the tautomeric ratios were used to explain the observed reactivities of the compounds toward N-7 alkylation.     

The deficiencies of meromorphic solutions of certain algebraic differential equations

We use the spread relation to prove estimates that contain the Nevanlinna deficiencies of values of meromorphic solutions of certain differential equations of the form (1.1) below. We construct examples which show that all of our estimates are sharp, and in most of these constructions we use functions which are extremal for the spread relation. Several other examples are also given to illustrate our results.     

Gas-phase pulsed power switches

A review of plasma science that is related to gas-phase pulsed power switching is presented. Switch plasmas include uniform glow-type plasmas and constricted arc-type plasmas, and the science involves understanding transport processes in hydrogen, helium, metal vapor, and other plasmas, and electrode processes including limitations related to cathode emission and sheaths. Gas-phase pulsed power switches include spark gaps, vacuum, metal vapor, and low-pressure glow-type switches. The review concludes that the understanding of microscopic processes and plasma electrode interactions is somewhat limited, and that to facilitate the development of efficient, reliable pulsed power devices, there is considerable need for a deeper understanding