Generalizations of Cole's Systems

There are four resolvable Steiner triple systems on fifteen elements. Some generalizations of these systems are presented here

Dynamic nuclear polarization NMR fast field cycling study complex systems

Die dynamische Kernpolarisation (DNP) ist eine Methode zur Erzielung eines außerordentlich hohen hyperpolarisierten Kernspinzustands, welche aufgrund der erhöhten Empfindlichkeit ein zusätzliches Potenzial für Kernspinresonanz (NMR) -Techniken bietet. Zudem ist die DNP- Methode sowohl für Anwendungen in niedrigen, als auch in hohen Magnetfeldern geeignet und ermöglicht dabei für eine Vielzahl von Messbedingungen und Messsystemen eine Verbesserung der Empfindlichkeit. In dieser Arbeit werden die bisherigen Ansätze zur Kombination der DNP-Methode mit der Fast-Field-Cycling (FFC) NMR-Relaxometrie weiterentwickelt, um die Molekulardynamik in komplexen Systemen zu untersuchen. Die zugehörigen Maßnahmen zur Verbesserung der Datenqualität und die ausführliche Datenanalyse werden ebenso vorgestellt, wie der theoretische Hintergrund der Methode. Anhand einer Vielzahl unterschiedlicher Systeme werden die verschiedenen Kombinationen von DNP-Effekten und Interaktionstypen, sowie verschiedene Dynamikmodelle vorgestellt. Die Verteilung der transversalen Relaxationszeit (T2) wird zum Kodieren entsprechender Messungen der longitudinalen Relaxationszeit (T1) und der T2- aufgelösten DNP-Verstärkungsmessungen verwendet. Außerdem wird das Hauptproblem von DNP-FFC-Messungen, welches mit der radikalinduzierter Relaxivität zusammenhängt, mithilfe eines neu entwickelten Differenzenansatzes (Extrapolation) gelöst. Als ein Modellsystem für komplexe Systeme wird ein Blockcopolymer bestehend aus Polystyrol und Polybutadien untersucht, welches sich durch unterschiedliche Dynamiken, Relaxationseigenschaften und Polymer-Lösungsmittel-Wechselwirkungen der verschiedenen Blöcke auszeichnet. Es wird gezeigt, dass für in organischen Lösungsmitteln mit stabilen organischen Radikalen wie TEMPO und BDPA gelöste Blockcopolymere eine Kombination aus Overhauser-Effekt und Festkörper-DNP-Effekt mit einem bemerkenswerten Verstärkungsfaktor vorliegt. In einem nächsten Schritt wird die DNP-FFC-Methode auf einen Satz verschiedener schwerer Rohöle angewendet, die sich in Viskosität, Zusammensetzung und der Menge an freien Radikalen und Vanadylkomplexen unterscheiden. Die Verwendung eines fortschrittlichen Festkörper-DNP-Effekt-Modells liefert Informationen über die Kopplungsstärke und das relative Verhältnis von gekoppelten Elektronen und Kernspins. Das neue Potenzial der Methode wird anhand der Untersuchung von X-Kernsystemen wie 7Li, 13C und 2H demonstriert. Durch die Verwendung der DNP-Methode ist es erstmals möglich, die Relaxationseigenschaften von 13C bei ihrer natürlichen Konzentration in Flüssigkeiten zu untersuchen. Zusammenfassend präsentiert diese Arbeit fortschrittliche Entwicklungen und Anwendungen einer neuartigen DNP-FFC-Methode zur Untersuchung der Molekulardynamik und der Merkmale der Elektron-Kern-Wechselwirkung in einer Vielzahl komplexer Systeme, die an Beispielen von Polymeren, Lösungen, porösen Medien und Mehrkomponentenflüssigkeiten vorgestellt werden. Die meisten der in der vorliegenden Arbeit zum ersten Mal untersuchten Systeme wurden zur Entwicklung der kombinierten Analyse verwendet, einschließlich konventioneller Relaxationsdispersions- und DNP-Ansätze, die es ermöglichen, einzigartige detaillierte Informationen über Dynamik und Elektron-Kern-Wechselwirkungen zu erhalten.Dynamic Nuclear Polarization (DNP) as a method to achieve a remarkably high hyperpolarized state of nuclear spins can provide an additional potential of Nuclear Magnetic Resonance (NMR) techniques due to increased sensitivity. In addition, the DNP technique is comparably versatile for applications either at low or high magnetic fields, allowing obtaining sensitivity enhancement in a wide range of study conditions and a variety of potentially studied systems. In this work, the advanced approaches of the dynamic nuclear polarization fast field -cycling relaxometry technique (DNP-FFC) are further developed to study molecular dynamics in complex systems. The corresponding procedures for improving data quality and additional in-depth analysis are presented with the relevant theoretical background. A variety of studied systems are presented in the current work as examples of a combination of different DNP effects and interaction types, as well as dynamics models. The distribution of T2 relaxation time is used for encoding corresponding measurements of T1 relaxation time and T2-resolved DNP enhancement measurements. Moreover, the main issue of DNP-FFC measurements related to radical-induced relaxivity is solved by using a newly developed difference (extrapolation) approach. A block copolymer of polystyrene and polybutadiene was chosen as one of the model systems with different dynamics, relaxation properties, and polymer-solvent interactions related to a particular block. It was shown that block copolymer in organic solvents with stable organic radicals, such as TEMPO and BDPA, exhibits a combination of the Overhauser effect and solid DNP effect with a remarkable enhancement factor. Further developing the current method, DNP-FFC was applied for the set of heavy crude oils, which are characterized by different free radical and vanadyl complex contents, viscosity, and components ratio. Using an advanced model of SE has been providing information about coupling strength and the relative ratio of coupled electron and nuclear spins. The new potential was shown in the field of studying X-nuclei systems such as 7Li, 13C, and 2H. The use of the DNP allowed obtaining relaxation dispersions of 13C of liquids at natural abundance for the first time. To summarize, this work presents advanced developments and applications of a novel DNP-FFC method to study molecular dynamics and features of electron-nuclear interaction in a wide range of complex systems, presented by polymers, solutions, porous media and multicomponent liquids. Most of the systems studied for the first time in the current work were employed to develop the combined analysis, including conventional relaxation dispersion and DNP approaches that allow obtaining unique detailed information about dynamics and electron-nuclear interactions

Non-exponential 1H and 2H NMR relaxation and self-diffusion in asphaltene-maltene solutions

The distribution of NMR relaxation times and diffusion coefficients in crude oils results from the vast number of different chemical species. In addition, the presence of asphaltenes provides different relaxation environments for the maltenes, generated by steric hindrance in the asphaltene aggregates and possibly by the spatial distribution of radicals. Since the dynamics of the maltenes is further modified by the interactions between maltenes and asphaltenes, these interactions - either through steric hindrances or promoted by aromatic-aromatic interactions - are of particular interest. Here, we aim at investigating the interaction between individual protonic and deuterated maltene species of different molecular size and aromaticity and the asphaltene macroaggregates by comparing the maltenes’ NMR relaxation (T1 and T2) and translational diffusion (D) properties in the absence and presence of the asphaltene in model solutions. The ratio of the average transverse and longitudinal relaxation rates, describing the non-exponential relaxation of the maltenes in the presence of the asphaltene, and its variation with respect to the asphaltene-free solutions are discussed. The relaxation experiments reveal an apparent slowing down of the maltenes’ dynamics in the presence of asphaltenes, which differs between the individual maltenes. While for single-chained alkylbenzenes, a plateau of the relaxation rate ratio was found for long aliphatic chains, no impact of the maltenes’ aromaticity on the maltene-asphaltene interaction was unambiguously found. In contrast, the reduced diffusion coefficients of the maltenes in presence of the asphaltenes differ little and are attributed to the overall increased viscosity

Realization of virtual information technologies in educational process of the educational organization of the higher education as the basis for increase of the professionalism and personal potential of students

В статье рассмотрены общие вопросы, касающиеся реализации виртуальных информационных технологий в образовательном процессе образовательной организации высшего образования по специальным дисциплинам в рамках повышения профессионализма и личностного потенциала обучающихся (молодежи) – формирования компетенций.In article the general questions concerning realization of virtual information technologies in educational process of the educational organization of the higher education for special disciplines within increase of the professionalism and personal potential of students (youth) – formation of competences are considered

Specificity and Time of the Appearance of His+ Reversions Induced by Histidine Starvation in Salmonella typhimurium

It was previously established that reversion of the hisG46 allele of Salmonella typhimurium to prototrophy occurred upon histidine starvation. In this paper, it was shown that histidine starvation does not affect the appearance of mutants resistant to L-arabinose and rifampicin. Threonine starvation did not change the frequency of His+ revertants. Analysis of His+ revertant clones did not reveal additional L-arabinose resistance mutations. Thus, these experiments allowed the conclusion that amino acid starvation does not lead to a non-specific increase in the mutation rate. In addition, it was shown that spontaneous His+ revertants start to arise after two to three hours of histidine starvation, and this process lasts for four days. Nevertheless, original His- cells did not grow in a culture generating His+ revertants. Traces of histidine and novobiocin added to a minimal medium retarded reversion realization. However, the occurrence of revertants was not markedly inhibited by chloramphenicol. Based on the results, it is assumed that adaptive His+ reversions occurred due to a special mode of replication induced upon histidine starvation and requiring no de novo protein synthesis

Study of the Distribution of Organic Molecules in the Porous Space of Vycor Glasses

© 2014, Springer-Verlag Wien. The melting crystallization processes of cyclohexane and dimethylsulfoxide adsorbed in porous glasses Vycor have been investigated by nuclear magnetic resonance method in a wide temperature range. It has been established that the adsorbed molecules form aggregates or clusters of different sizes depending on the polarity of the adsorbed fluid. In addition, this effect leads to an inhomogeneous distribution of the adsorbed non-polar molecules in the porous volume of porous glasses Vycor. It has been shown based on the analysis of the temperature dependence of the relative proportion of the amorphous component that the molecules of the adsorbed fluid can be part of different “phases” below the melting temperature at concentration corresponding to the monolayer filling: (1) the molecules in the crystalline state, (2) the molecules in amorphous “non-frozen” layer, (3) molecules in the amorphous state on the surface which are not included in the “non-frozen” layer, and (4) the molecules in the nanopores

Nuclear magnetic relaxation and phase transitions of diethylene glycol in Vycor porous glasses

The times of longitudinal T 1 and transverse T 2 magnetic relaxation of protons of diethylene glycol in the bulk phase and in Vycor porous glasses with average pore radii of 4, 11, and 32 nm are measured by the pulse NMR method in the 172-350 K temperature range. It is found that, for all samples of porous glasses, the crystallization of diethylene glycol is not observed if its content corresponds to the monolayer surface filling. The minimum content of diethylene glycol, which makes it possible to cause its crystallization in porous glass, is determined. By analyzing the dependence of the characteristics of a component with T 2b = 20-40 μs in the transverse magnetization decay on the content of diethylene glycol in porous glasses, the volume of nanopores comparable in size with diethylene glycol molecule is estimated. © 2010 Pleiades Publishing, Ltd