Rock porosity determination by combination of X-ray computerized tomography with mercury porosimetry

First results are described of coupling of mercury porosimetry with X-ray computerized tomography (CT) as a new combination technique for rock porosity studies. This technique is suitable for rock samples with a pronounced mercury intrusion-extrusion hysteresis and includes CT measurements before and after mercury intrusion. The entrapped portion of mercury, when the pressure after the intrusion into the rock sample is reduced to 0.1 MPa, serves as a contrast agent in the porous network to localize spatial distribution of rock porosity by CT. The results obtained show that the mercury intrusion and therefore the porosity were quite different for the separate mineral phases. Therefore the combination of mercury porosimetry and computer tomography can give 3-D data on mineral-specific porosity distributions with additional pore size information. In contrast to mercury porosimetry as a single method, results of the combination technique with CT represent a direct visualization of porosity variation and do not depend on any special pore network model. Received: 2 July 1996 / Revised: 20 November 1996 / Accepted: 22 November 1996     

Dioxygen activation by a low-valent cobalt complex employing a flexible tripodal N-heterocyclic carbene ligand

The novel versatile cobalt(I) tris-carbene complex [(TIMEN(xyl))Co]Cl (1) (where TIMEN = (tris[2-(3-arylimidazol-2-ylidene)ethyl]amine) reacts with CO, one-electron oxidizers such as CH(2)Cl(2), and O(2) to yield the cobalt complexes [(TIMEN(xyl))Co(CO)]Cl (2), [(TIMEN(xyl))Co(Cl)]Cl (3), and peroxo species [(TIMEN(xyl))Co(O(2))](BPh(4)) (5). All new complexes were fully characterized by (1)H NMR, UV/vis, and IR spectroscopy as well as superconducting quantum interference device (SQUID) magnetization measurements and single-crystal X-ray crystallography. The nucleophilic character of the eta(2)-bound dioxygen ligand in 5 was confirmed by density functional theory (DFT) studies and allows for oxygen-transfer reactions with electron-deficient organic substrates, such as benzoyl chloride.     

Fluorometric assay of histamine in tissues and body fluids: Choice of the purification procedure and identification in the nanogram range

Summary Several procedures for the isolation of histamine from tissues and body fluids were examined. For the fluorometric assay of histamine concentrations higher than 1 g/g tissue or ml blood the extraction into n-butanol as well as the cation-exchange chromatography on Dowex 50W-X8 proved suitable. The determination of histamine in whole blood of dogs gave valid results only after chromatography on Dowex 50, in human plasma and gastric juice only after the combined application of both purification methods. Histamine was identified by thin-layer chromatography on cellulose, by inactivation in the presence of purified diamine oxidase from pig kidney and purified histamine methyltransferase from guinea-pig brain, by the biological activities and by the fluorescence spectra of the condensation product between histamine and o-phthaldialdehyde. Histamine concentrations in tissues and body fluids of man and some laboratory animals are reported.

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Fluorimetrische Bestimmung von Histamin in Geweben und Körperflüssigkeiten: Wahl eines geeigneten Reinigungsverfahrens und Identifizierung im ng-Bereich

Zusammenfassung Verschiedene Isolierungsverfahren für Histamin zur fluorimetrischen Bestimmung wurden geprüft. Für Histamingehalte von mehr als 1 g/g Gewebe oder Milliliter Vollblut eignet sich sowohl die Butanolextraktion als auch die Ionenaustausch-Chromatographie an Dowex 50W-X8, für Vollblut des Hundes nur das letztere Verfahren, für Plasma und Magensaft des Menschen nur die Kombination der beiden Isolierungsmethoden. Histamin wurde identifiziert durch Dünnschicht-Chromatographie auf Cellulose, Umsatz durch angereicherte Diaminoxydase und Histaminmethyltransferase, durch die Fluorescenzspektren nach Kondensation mit o-Phthaldialdehyd und durch seine biologische Aktivität. Die Histamingehalte in Geweben und Körperflüssigkeiten des Menschen und einiger Versuchstiere werden mitgeteilt.

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Members of SFB 37 (Restitution und Substitution innerer Organe of Deutsche Forschungsgemeinschaft).     

Eine spektroskopische Methode zur Untersuchung des Anfangsstadiums der Metallschichtbildung auf Glas

A simple detection of light metallic deposits (e. g. nickel) on oxidic surfaces can be achieved by means of the spectroscopical measurement of the concentration of hydrogen atoms in the positive column of a glow discharge. – The kinetics analysis of the experimental results shows that the velocity of forming as well as the heterogeneous recombination of hydrogen atoms depend on the amount of nickel being deposited on the surface area. The kinetic data allow conclusions to be drawn concerning the process and velocity of metallic deposits on glass surfaces. The initial phase of film forming, hitherto experimentally difficult to follow, can thus be studied. Measurements of the electrical resistance show the island structure of the thin nickel films. Due to the surface diffusion of hydrogen atoms such a discontinuous film exhibits the same catalytic activity for the recombination of hydrogen atoms as a continuous film.     

Synthesis and Characterization of Catechol-Containing Polyacrylamides with Adhesive Properties

In this study, a row of four analogous dopamine acryl- and methacrylamide derivatives, namely N-(3,4-dihydroxyphenyethyl) acrylamide, N-(3,4-dihydroxyphenyethyl) meth acrylamide, N-phenethyl methacrylamide, N-(4-hydroxyphenethyl) methacrylamide were synthesized and characterized by ¹H-NMR and ¹³C-NMR, followed by further solvent-based radical polymerization with N-hydroxyethyl acrylamide. All copolymers were characterized by ¹H-NMR, dynamic differential calorimetry, and gel permeation chromatography. The dependency of the used comonomer ratios to the molecular mass of the corresponding copolymers has been described. The synthesis of the various polymers serves as a feasibility study and provides important data for a future biometric application in the medical field. We synthesized N-(3,4-dihydroxyphenyethyl) acrylamide copolymer up to 80 mol% by free radical polymerization without using any protecting groups. All polymers show identical perfect adhesive properties by a simple scratch test. Further, the monomers were used as a photo reactive glue formulation to test its adherence to a medical titanium surface sample by tensile shear test.