Synthesis of an inorganic-organic polymer blend from orthoboric acid and caprolactam

The possibility of modifying boron polyoxide with an oligomeric amide upon thermal dehydration of orthoboric acid and oligomerization of caprolactam in a common melt is shown. The products obtained after thermal pretreatment of the initial blend containing 30 wt % caprolactam are investigated. It is shown that the main processes at T < 200°C are dehydration of orthoboric acid and hydrolysis of caprolactam with the formation of ε-aminocaproic acid. At temperatures of 225–260°C, the predominant process is the formation of boron polyoxide and a caprolactam-based oligomeric product. The data of ¹¹B NMR spectroscopy show that the chemical transformations of caprolactam occur against the background of the N:B donor-acceptor interaction. The two-dimensional [¹¹B-¹H] heteronuclear correlation spectrum indicates that the systems obtained upon thermal treatment are solid solutions.     

NMR analysis of mixtures using hyphenation techniques and software

Two approaches to NMR analysis of mixtures used in Bruker instruments are considered: (1) a combination of high-performance liquid chromatography, NMR, and mass spectrometry, (2) the use of specialized software and spectral databases.     

Vasodilatation Function of Cerebral Vessels at Arterial Hypertension in OXYS Rats

OXYS rats represent a selection strain of laboratory animals, which are characterized by the accelerated senescence. Substantial morphologic changes of cerebral vessels were revealed in the senescence-accelerated OXYS rats by the noninvasive MRI diagnostics using the induced arterial hypertension and the author’s original methods. These changes appeared as vascular lesions with a thickening of the intimae and the increasing of the signal intensity from blood in cerebral vessels. Cerebral arterial hypertension in normotensive Wistar rats developed as result of intraperitoneal injections of hydrocortisone acetate and diet enriched by sodium ions. The pathology of cerebral vessels in OXYS rats began its development much earlier and was based on spontaneous hypertension in connection with initially elevated blood pressure as well as the genotype of the animals. Four different inductors (two vasodilators and two vasoconstrictors) were used in the study of the endothelium-independent and endothelium-dependent vasodilatation and vasoconstrictions. We have compared previously unknown effects of these inductors on cerebral vessels in senescence-accelerated OXYS rats and those in normal Wistar rats. The response of the arteries to the action of inductors showed changes in the status of anterior, middle, and posterior cerebral arteries of circle Willis. Thus, we have indicated the changes in compensatory and adaptive characters of arteries in hypertensive OXYS rats in comparison with hypertensive Wistar rats. Reduced vasodilator response in the middle cerebral arteries suggests an elevated risk for development of arterial hypertension in these rats.     

Spektrochemische Untersuchungen zur geologischen Altersbestimmung nach der Rubidium-Strontium-Methode

Zusammenfassung Durch die Einführung röntgenfluorescenzspektroskopischer Arbeitsmethoden kann die Anwendungsmöglichkeit der Rubidium-StrontiumMethode zur geologischen Altersbestimmung wesentlich vereinfacht und verbreitert werden. Die erforderliche Isotopenanalyse ist durch Untersuchung der Hyperfeinstruktur der Strontiumlinie 4078 Å mit relativ einfachen Hilfsmitteln möglich, allerdings erhöht sich dabei die Unsicherheit der Alterswerte um 10–15% bei photographischer bzw. ca. 3% bei lichtelektrischer Messung gegenüber der Verwendung eines Massenspektrometers.Es werden Arbeitsmethoden angegeben, welche gestatten: 1. eine rasche Auswahl geeigneter Proben zu treffen, 2. die Bestimmung des Gewichtsverhältnisses Sr/Rb ohne jede chemische Vorbehandlung der Proben durchzuführen, 3. eine Isotopenanalyse des Strontiums auf rein optisch-spektroskopischem Wege auszuführen.Das geologische Alter der Lagerstätte Varuträsk (Schweden) wurde zu (1695±290) · 10⁶ Jahren, das einer Lagerstätte in Südafrika zu (1800 +145/–220) · 10⁶ Jahren bestimmt.

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Summary X-ray fluorescence offers the possibility for an easier and wider application of the rubidium-strontium method for geological age determination. The determination of the isotopic composition of the isolated strontium can be carried out with relatively simple equipment by hyperfine structure-analysis of the Sr line 4078 Å. The error of the age values will in this case increase by 10–15% as compared to a mass-spectrometric determination.Methods are described for: 1. quick selection of useful samples; 2. determination of the weight ratio Sr/Rb without any chemical pre-treatment; 3. isotope analysis of strontium by merely optical means.The geological age of the deposit Varuträsk (Sweden) is determined to be (1695 ±290)×10⁶ years, that of a deposit in South-Africa to be (1800+145/–220)×10⁶ years.

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Herrn Prof. Dr. F. Strassmann zum 65. Geburtstag gewidmet.

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Auszug aus der Habilitationsschrift, Mainz 1961.

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Herrn Prof. Dr. F. Strassmann danke ich für die Anregung zu dieser Arbeit, wertvolle Diskussionen und die Bereitstellung der Hilfsmittel des Institutes.     

Identifizierung und Bestimmung polycyclischer, aromatischer Kohlenwasserstoffe durch Fluorescenzspektren fester L?sungen bei tiefen Temperaturen

Zusammenfassung Es wird eine Apparatur zur Aufnahme von Fluorescenzspektren fester Lösungen bei tiefen Temperaturen beschrieben. Sie stellt in Verbindung mit einem Monochromator und einer lichtelektrischen Registrieranordnung eine empfindliche Meßanordnung dar, mit der noch 4 · 10^–11 g 3,4-Benzpyren nachgewiesen werden können.Es werden die Fluorescenzspektren von Anthracen, 3,4-Benzpyren, 1.2,5.6-Dibenzanthracen und 20-Methylcholanthren in n-Heptan bei 79° K untersucht. Sie zeigen differenzierte Unterschiede und gestatten den Nachweis aller 4 Verbindungen nebeneinander.Die Auftrennung des Gemisches erfolgte chromatographisch an teilacetyliertem Papier. Das Verfahren wurde auf die Analyse von Luftstaub angewendet. In einer Staubprobe wurde die Konzentration an 3,4-Benzpyren mit 0,05–0,1 g/1000 m³ Luft bestimmt.     

NMR microscopy - limitations and applications in material sciences -

Alongside the numerous applications of NMR spectroscopy in analytical chemistry, materials sciences and morphological studies by magnetic resonance imaging (MRI), NMR microscopy makes possible a whole new range of applications in materials sciences such as the development and non destructive testing of polymers and ceramic materials. This includes imaging of microscopic structures and structural changes in such materials. The contrast in the images is determined by the NMR specific parameters chemical shift δ, spin density ρ, spin lattice relaxation time T₁, spin spin relaxation time T₂ and spin lattice relaxation time in the rotating frame T_1ρ. The numerous well developed methods available make it possible to study dynamic processes by fast imaging, the measurement of diffusion constants of solvents or liquids, the mobility of fluids in polymers or ceramics or the three dimensional evaluation of pore sizes in porous materials.     

Investigation of electron transfer processes in organic molecules and metal complexes by means of electrolysis-EPR

Kinetics of electrochemical reduction of trialkylphosphates, slow homogeneous electron transfer reaction with the participation of paramagnetic intermediates and multispin Co(II)-, Cu(II)-, Zn(II),-nitroxyde radical systems reduction processes are studied with the help of combining electrochemical method and EPR.     

Molecular dynamics of (Z)-1-(2-hydroxy-5-methyl-3-nitrophenyl)ethanone oxime and (E)-2-hydroxy-5-methylacetophenone thiosemicarbazone in solution studied by NMR spectroscopy

The formation of hydrogen bonds and the molecular dynamics for molecules (Z)-1-(2-hydroxy-5-methyl-3-nitrophenyl)ethanone oxime and (E)-2-hydroxy-5-methylacetophenone thiosemicarbazone, (E)-4-bromoacetophenone thiosemicarbazone have been investigated in solution using NMR. The results confirm the formation of different O-H…O type intramolecular hydrogen bonds in the oxime molecule. The rotational barrier energy and energy of intramolecular hydrogen bonds have been determined.     

Über die Genauigkeit spektrochemischer Additionsverfahren

Zusammenfassung Berechnung der bei spektrochemischen Additionsverfahren möglichen Maximalfehler für einige praktisch wichtige Fälle und Vergleich mit experimentellen Ergebnissen.

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Summary Calculation of the possible maximum error in spectrochemical addition procedures for several practically important cases and comparison with experimental findings.

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Résumé Calcul de l'erreur maximum possible dans le procédé d'analyse spectrochimique par addition dans plusieurs cas importants et comparaison avec des résultats expérimentaux.

     

Measurement of the coefficient of translational diffusion in liquid solutions by means of EPR

A new method of diffusion coefficient measurement in liquids under electrolysis is considered. It is shown that the diffusion parameters can be correctly determined from the dependence on the electrolysis time of the EPR signal intensity of the ion radicals formed.