On the porous structure of coals: Evidence for an interconnected but constricted micropore system and implications for coalbed methane recovery

An experimental and theoretical study of adsorption and diffusion of carbon dioxide and methane in coals of widely varying rank was carried out. Low pressures adsorption isotherms of CO₂ were obtained and analyzed using Dubinin's theory of volume filling of micropores. High-pressure adsorption isotherms of CH₄ were obtained and analyzed using tracer pulse chromatography in conjunction with an appropriate adsorption/diffusion model. A preliminary¹²⁹Xe NMR analysis of chemical shifts experienced by xenon atoms in particles of different sizes is also reported.The heretofore undocumented and/or underestimated effects of activated diffusion of CO₂ at 273–298 K complicate the elucidation of the true microporous structure of coals, especially its dependence on coal rank. Activated diffusion of both CO₂ and methane at room temperature does not allow reliable estimates of coalbed gas content to be made. A model of an interconnected network of pores which includes randomly distributed, numerous and ultramicroporous constrictions (at any size scale) is consistent with all these experimental and theoretical findings.Presented in part at the International Conference on Coal Science, Banff, Alberta, Canada. September 1993, and at the 21st Biennial Conference on Carbon, Buffalo, NY, June 1993.     

Conductometric estimation of thorium in dilute thorium chloride

Summary Conductometric titrations of thorium chloride against oxalic acid, ammonium oxalate and silver nitrate have been carried out at high dilutions (0.001, 0.0005 and 0.00033 M) of the chloride. Oxalic acid is found to be a suitable titrant for rapid estimation of thorium, the minimum error being +0.5%. The other titrants do not give good results. The titrations with ammonium oxalate indicate the step-wise ionisation of ThCl₄ into ThCl₂ ²⁺, ThCl³⁺ and Th⁴⁺. For mixtures of thorium chloride and cerous chloride, only the equivalence point corresponding to complete precipitation of both thorium and cerium is indicated.The authors express their sincere thanks to Prof. S. S.Joshi for his keen interest in this work and to Dr. G. S.Deshmukh for his advice and help in so many ways during the progress of these studies.     

Identification of aminophospholipid stereomers by positive-ion fast atom bombardment combined with collisional activation mass-analysed ion kinetic energy analysis and high-performance liquid chromatography

Two methods for the identification of aminophospholipid stereomers are described. After a chemical derivatization, 9-fluorenylmethoxycarbonyl derivatives of diacyl-sn-2- and diacyl-sn-3-phosphoserine and diacyl-sn-2- and diacyl-sn-3-phosphoethanolamine can be characterized by positive-ion fast atom bombardment combined with collisional activation mass-analysed ion kinetic energy analysis based on the differentiation of relative abundances [M + H + diethanolamine ? 89]⁺ and [M + H]⁺ fragments derived from [M + H + diethanolamine]⁺ ions, the protonated solvated molecules, and normal phase high-performance liquid chromatography on the basis of different elution times of the derivatives of the aminophospholipid stereomers on an aminopropyl-bonded column.     

Selective Extraction and Inductively Coupled Plasma Atomic Emission Spectrophotometric Determination of Thorium Using a Chromogenic Crown Ether

A method for the preconcentration and trace determination of thorium with crown hydroxamic acid (NHDTAHA) is described. The thorium is extracted from the chloroform solution of NHDTAHA at pH 4 which gives a colourless extract, _max = 365 nm; = 9.4·10^–3 l·mol^–1·cm^–1. The extract is directly inserted in the plasma for ICP-AES measurements of thorium. A linear calibration graph was obtained between 15–150 ng·ml^–:1 of thorium. The proposed method has been applied for the determination of thorium in the presence of several diverse ions in monazite sand, rare earth sand and in sea water.     

Detection, distribution, and quantification of carbon in steel microstructures by PEELS.

This work concerns the use of parallel electron energy loss spectroscopy (PEELS) to investigate the detection, distribution, and quantification of carbon in various steel microstructures generated by rapid cooling rates or by isothermal transformation. The feasibility of detecting C in steels containing very small amounts of carbon was first examined by calculating the minimum detectable mass fraction for a variety of binary Fe-C alloy specimen thicknesses and microscope conditions. These theoretical studies indicated that the detection of carbon in steel microconstituents containing about 0.01 wt.% (or even less) was easily possible with an analytical transmission electron microscope equipped with a LaB6 emitter and a PEEL spectrometer. These theoretical calculations seemed to be reasonable, as it proved possible to make a quantitative PEELS study of the partitioning between the microconstituents ferrite, retained austenite, and martensite found in an ultralow carbon (0.03 wt.%) steel weld metal provided care was taken to avoid hydrocarbon contamination. Studies of both carbon and molybdenum segregation to ferrite/martensite interfaces in an isothermally transformed Fe-C-Mo alloy were also carried out in order to investigate the nature of the "solute drag" effect in this alloy system.     

Phototoxicity against tumor cells and Sindbis virus by an octahedral rhodium bisbipyridyl complex and evidence for the genome as a target in viral photoinactivation

An octahedral rhodium complex (cis-dichloro(dipyrido[3,2a-2',3'c]phenazine)(1,10-phenanthroline)rhodium(III) chloride; DPPZPHEN) has been prepared that can penetrate tumor cell membranes and the Sindbis viral capsid. The compound is phototoxic to these entities when irradiated with UVA light. Model studies with calf thymus and supercoiled plasmid DNA indicate that the complex can both bind with, and nick, nucleic acid. Analysis of Sindbis virus, following irradiation with the metal complex, confirmed that the viral genome was rendered noninfectious by this treatment.