Fluor-induzierte intramolekulare Aryl-Aryl-Kupplung : ein Beitrag zur Isomer-spezifischen Fullerensynthese

Direct synthesis of fullerenes is of considerable interest as a method to access new fullerenes which cannot be obtained in the uncontrolled process of graphite evaporation or form in low yields as a “hard-to-isolate” mixture. The general strategy of the direct approach to fullerenes is based on the synthesis of polycyclic aromatic hydrocarbons (PAH) that already contain the required carbon framework. Such “unrolled” molecules can be “rolled up” to form fullerenes through intramolecular Aryl-Aryl condensation under flash vacuum pyrolysis (FVP) conditions. The presence of chlorine or bromine in the initial precursor is essential for effective Aryl-Aryl condensation via free radical mechanism. On the other hand the use of chlorine and bromine functionalizations reaches its limits in the case of large molecules such as fullerene precursors. Availability of alternative promoters which do not have these disadvantages is a key prerequisite for successful direct fullerene synthesis. In this work various functional groups have been tested as alternative promoters of Aryl-Aryl intramolecular condensation under FVP conditions. Methyl and fluorine functionalization has been found to be promising approaches. Unexpected high selectivity in cyclization was observed for fluorine derivatives. It was found that HF elimination is a synchronous process leading directly to the target molecule without any intermediates, thus producing no side products. The small size and low molecular weight of fluorine as well as high thermostability of the C-F bond, makes fluorine a “perfect” activating group for rational fullerene synthesis. Since fluorine can promote the desired ring closure only if hydrogen is placed neighboring in space in the precursor structure, full control in the direction of the condensation can be achieved. It was shown that the use of fluorine, as an activating group, solves the problem of selectivity in FVP and provides an effective conversion of the respective PAH precursors. Several fullerene precursors containing fluorine atoms in key positions have been synthesized and investigated as a precursor for direct fullerene synthesis. Furthermore optimization has led to the discovery of a highly effective alternative solid-state strategy for intramolecular Aryl-Aryl coupling via HF elimination. The efficiency of the approach has been demonstrated by quantitative transformation of the precursor molecules to the desired PAHs and buckybowl structures. The quantitative conversion to the extended C46 buckybowl, representing more than 75% of the C60 fullerene connectivity, demonstrates the high potential of the technique for construction of extended non-planar carbon based nanostructures, including higher fullerenes, giant buckybowls and nanotubes. The results obtained point the way to the fabrication fullerenes as well as other carbon based nanostructures such as single walled nanotubes and nanoribbons in a fully controllable manner.Im Rahmen dieser Arbeit wurde Grundlagenforschung zur rationalen Synthese von Fullerenen durchgeführt. Das Hauptaugenmerk liegt auf der Direktsynthese von isomerenreinen höheren Fullerenen und Buckybowls, wobei die entwickelten Methoden jedoch auch auf eine Vielzahl weiterer Kohlenstoffnanostrukturen ausgeweitet werden können. Die allgemeine Strategie der Direktsynthese basiert auf der Synthese von Vorläufermolekülen – polyzyklischen aromatischen Kohlenwasserstoffen (PAKs) mit der für das Zielfulleren benötigten Kohlenstoffkonnektivität

Mechanisms of retroviral replication

Specific encapsidation of viral RNA is an essential step of retroviral replication cycle. Extensive biochemical and genetic analyses suggest that majority of retroviruses employ similar mechanisms for specific RNA packaging. Better understanding of mechanisms of this process may help to develop new anti-retroviral drugs against such serious pathogens as human immunodeficiency virus types 1 and 2.;This study concerns with specific packaging of RNA by two simple retroviruses, murine leukemia virus (MLV) and spleen necrosis virus (SNV). SNV proteins can package RNA of both SNV and MLV with similar efficiency. In contrast, MLV proteins cannot package SNV RNA. NC domain was shown to be the determinant of nonreciprocal RNA recognition by these two viruses.;This study was intended to determine biological activities of previously generated MLV- and SNV-derived Gag-Pol chimeras that retained ability to specifically package viral RNA, but rendered viruses non-infectious. We investigated the role of Cys-His box and basic amino acids in non-reciprocal RNA packaging. Also, we examined contribution of single amino acids within Cys-His box to RNA selectivity of viral proteins. Series of MLV- and SNV-derived Gag-Pol chimera expression constructs with exchanged NC fragments or single amino acids were made. They were tested for non-reciprocal RNA packaging

Testy produktywności otworów horyzontalnych

Horizontal drilling technology has significantly influenced the industry's approach to the development and recovery of hydrocarbons. Advances in drilling technology have led to improved well productivity, increased drainage areas, especially in low permeability reservoirs. These day companies adopted an approach that has assigned a high priority to monitoring horizontal wells in order to maximize benefits. The testing and logging programs are aimed to assess the flow profile of the horizontal wells, optimize well production rates and plan future production and workover strategies. For this reason development of new methods and technologies has become crucial. This paper covers peculiarities of production logging test techniques used in horizontal wells. This includes technological as well as technical innovations based on deeper understanding of the phenomena through detailed research of this area.W pracy przedstawiono specyfikę technik rejestrowania produktywności otworów horyzontalnych. Omówiono technologiczne oraz techniczne innowacje oparte na głębszym zrozumieniu zjawisk, dzięki przeprowadzeniu szczegółowych badań tego obszaru

Surface Plasmon-Enhanced Switching Kinetics of Molecular Photochromic Films on Gold Nanohole Arrays

Diarylethene molecules are discussed as possible optical switches, which can reversibly transition between completely conjugated (closed) and nonconjugated (open) forms with different electrical conductance and optical absorbance, by exposure to UV and visible light. However, in general the opening reaction exhibits much lower quantum yield than the closing process, hindering their usage in optoelectronic devices. To enhance the opening process, which is supported by visible light, we employ the plasmonic field enhancement of gold films perforated with nanoholes. We show that gold nanohole arrays reveal strong optical transmission in the visible range (∼60%) and pronounced enhancement of field intensities, resulting in around 50% faster switching kinetics of the molecular species in comparison with quartz substrates. The experimental UV–vis measurements are verified with finite-difference time-domain simulation that confirm the obtained results. Thus, we propose gold nanohole arrays as transparent and conductive plasmonic material that accelerates visible-light-triggered chemical reactions including molecular switching

Modelowanie wypierania ropy przez iniekcję ciepłej wody przez odśrodkowe kanały o wysokiej przepuszczalności

In this paper we investigate the efficiency of water-oil displacement by injecting hot water into the stratum through the highly permeable radial channels, created by jetting method of drilling. Increasing of the oil recovery factor and the volume of cumulative production by 7-12% showed as a result of our calculations.W niniejszym artykule opisano badania wydajności wypierania ropy przez wstrzyknięcie ciepłej wody w warstwę przepuszczalną przez kanały promieniste o dużej przepuszczalności, wytworzone metodą "jettingu". W wyniku przeprowadzonych obliczeń stwierdzono zwiększenie współczynnika wydobycia ropy naftowej oraz całkowitej wielkości produkcji o 7-12%