Computational Study of Lawesson’s Reagent Mediated Fluorenone Dimerization Forming 9,9’-Bifluorenylidene

The ambition of this work is to start a path to the a priori rational design of high yield production for electron acceptors with finely tuned band gaps, from the comfort of an armchair. To this end, organic photovoltaics offer a cheap and sustainable means of manufacture using readily available materials and avoids the toxicity of some of the heavy metals used in first and second-generation solar cells such as cadmium. The microwave assisted Lawesson’s reagent mediated one-pot one-step solventless synthesis takes less than 3 minutes and results in an 84% yield of 9,9’-bifluorenylidene from two equivalents of fluorenone. While fullerenes have traditionally been the most widely used electron acceptors in organic photovoltaics, bifluorenylidenes have been gaining attention due to their superior absorption in the visible spectrum, highly tunable band gap and cheap/efficient synthesis. Using an analog system to study the reaction divided into two parts; intermediate formation and sulfur extrusion, a molecular pathway has been devised that fits the reaction conditions and explains differences in % yields of substituted 9,9’-bifluorenylidenes reported in a manner readily conducive to making predictions based on the substituents chosen in the 9-fluorenylidene scaffold

An Experimental Investigation in a Turbulent Channel Flow With a Thick Viscous Sublayer (Hot-Film Measurements in Oil)

In a turbulent channel-flow hot-film measurements have been made. To achieve a sublayer thickness of approximately 1 cm at y+ = 10, oil was used. The Reynolds numbers used for the investigations were 5,600 and 8,200 based on the channel-width of 22 cm and the channel center-line velocity. In the vicinity of the wall, y+ \u3c 0.1, the u\u27-fluctuations were found to be proportional to the wall distance, y+. The u\u27-values obtained with a hot-film probe for y+ \u3e 0.7 were all greater than those obtained with a hot-film wall probe, but extrapolation of the data from the movable hot-film probe to the wall gave good agreement with the data from the flush-mounted wall-film probe. The instantaneous values of the u\u27-fluctuations in the region 0 \u3c y+ \u3c 5 are very similar to the instantaneous values of the wall-gradient, but there is a time shift which is proportional to the wall distance, y+. Disturbances in the flow in this region were observed to be convected with a constant velocity toward the wall. The mean value of the convection velocity was found to be approximately equal to the friction velocity, uT. The Reynolds stress was found to be intermittent in the vicinity of the wall with high peak to mean ratios. It was found that the probability density of the instantaneous streamwise velocity is skewed for all y+ values except y+ ≈ 13. For y+ \u3c 13 the most probable instantaneous velocity is less than the mean velocity; for y+ \u3e 13 the opposite was found

Geschichte in Bildern. Barbara Yelins „Irmina“ und Geschichtsschreibung im Comic

Auch der 2014 veröffentlichte Comic „Irmina“, um den es hier gehen soll, entworfen und gezeichnet von der Berliner Comic-Autorin Barbara Yelin, behandelt eine Familiengeschichte im Deutschland der 1930er- und 40er-Jahre. „Irmina“ basiert auf Tagebüchern und Briefen ihrer Großmutter, auf die die Autorin vor einigen Jahren gestoßen ist. Wie nah die Geschichte sich an diesen Aufzeichnungen orientiert, bleibt offen, deutlich wird aber, dass dem Buch ausführliche historische Recherchen zugrunde liegen. Dabei nutzt Yelin, wie ich darlegen möchte, genau jene Potenziale des Comics, die das Medium für die Geschichtsschreibung bereithält

Ad-hoc-AG Boden

Die Ad-hoc-AG Boden ist ein Gremium des Bund-/Länderausschusses Bodenforschung, dessen Aufgabe die Herausgabe von Kartieranleitungen, von länderübergreifenden Kartenwerken und von einschlägigen Methoden zur Bewertung von Böden ist. Es wird die Historie der AG dargestellt, ferner wesentliche Produkte und Angebote in Buchhandel und im Interne

XRCC1 PLAYS DIVERSE ROLES IN DNA STRAND BREAK REPAIR AND HUMAN DISEASE

Microhomology-mediated end joining (MMEJ), an error-prone pathway for DNA double-strand break (DSB) repair, is implicated in genomic rearrangement and oncogenic transformation; however, its contribution to repair of radiation-induced DSBs has not been characterized. We used recircularization of a linearized plasmid to recapitulate DSB repair via MMEJ or nonhomologous end-joining (NHEJ). MMEJ was significantly enhanced in irradiated cells, independent of their radiation-induced arrest in the G2/M phase. MMEJ activation was dependent on XRCC1 phosphorylation by casein kinase 2 (CK2), enhancing XRCC1's interaction with the end resection enzymes MRE11 and CtIP. Both endonuclease and exonuclease activities of MRE11 were required for MMEJ. Furthermore, the XRCC1 co-immunoprecipitate complex (IP) displayed MMEJ activity in vitro, which was significantly elevated after irradiation. Our studies thus suggest that radiation-mediated enhancement of MMEJ in cells surviving radiation therapy may contribute to their radioresistance and could be therapeutically targeted. Homologous recombination (HR)-deficient cancers, especially those with mutations in BRCA1 or BRCA2, utilize alternative methods of DNA double-strand break (DSB) repair, in particular microhomology-mediated end joining (MMEJ), for repair of DSBs that arise in S/G2 cell cycle phases as a result of replication stress. Depletion of MMEJ factors, including XRCC1, PARP1, and POLQ, is synthetic lethal with BRCA2 deficiency. While POLQ and PARP1 have been well-studied in the context of HR-deficiency, whether XRCC1 participates in MMEJ in HR-deficient cancers is unknown. We used a variety of approaches to demonstrate XRCC1’s critical role in MMEJ in BRCA2-deficient cells, and discovered that XRCC1 forms an active repair complex with POLQ and MRE11 after replication stress that has MMEJ activity in vitro. Formation of this complex was suppressed by BRCA2. Moreover, XRCC1 contributed to replication fork restart and fork degradation in BRCA2-deficient cells. Expression of XRCC1 is altered in HR-deficient cancers, along with other DNA repair factors in the same region of chromosome 19. Collectively, these studies identify new roles for XRCC1 in HR-deficient cancers and suggest chemotherapeutic strategies targeting MMEJ complex formation

From isophthalamides to supramolecular dendrimers

Erstmals konnte ein supramolekulares Dendrimer mit Hilfe von orthogonalen Erkennungsdomänen aufgebaut und untersucht werden. Hierzu wurden im Rahmen dieser Dissertation viele verschiedene Erkennungsbausteine synthetisiert und mit den entsprechenden Bindepartnern in 1H-NMR-Titrationen, 1H-NMR-Diffusionsexperimenten und ITC-Messungen analysiert.Dabei konnte durch die Einführung von verzweigten Alkylketten, Ethylenglykolketten und Ethern bzw. Estern die Löslichkeit der einzelnen Bausteine erheblich erhöht werden. Zudem konnten verschiedene Isocyanursäure-Kerne erhalten werden. Die Synthese neuer Hamilton-Rezeptoren ermöglicht nun den Aufbau weiterer Dendrimere.In Zusammenarbeit mit FISCHMANN und SAGGIOMO konnte ein konkaver Bimakrozyklus erhalten werden, der in der Lage ist, Dimethylsulfoxid und Pyridin-N-oxid in organischen Lösungsmitteln zu binden. Durch die Entwicklung einer neuen Berechnungsmethode kann mit wenigen Experimenten eine Vielzahl von möglichen Gästen untersucht werden. Durch die Synthese eines tritopen Makrozyklus ist es erstmals gelungen, u. a. Calciumchlorid als Ionentriplett in einem organischen Lösungsmittel zu binden. Der Makrozyklus ist in der Lage, die Salze aus dem Feststoff in die Lösung zu extrahieren. Weitere Experimente zum Thema Löslich- und Mischbarkeiten konnten veranschaulichen, dass Vorhersagen zum Verhalten bei Extraktionsversuchen nicht immer möglich sind.For the first time, a supramolecular dendrimer with orthogonal recognition domains was built up. In this thesis, several different recognition motifs were synthesized and analyzed. Their binding was investigated by 1H NMR titration, 1H NMR diffusion experiments and ITC measurements. To increase the solubility of the building blocks, branched alkyl chains, ethylene glycol chains, ethers and esters were introduced. Furthermore, the synthesis of different isocyanuric acid cores and several Hamilton receptors made the construction of supramolecular dendrimers possible. A novel concave bimacrocycle was obtained in collaboration with FISCHMANN and SAGGIOMO. This receptor was able to bind dimethylsulfoxide and pyridine-N-oxide in organic solvents. A new calculation method was developed to scan several possible guests with little effort. A tritopic macrocycle was synthesized to bind calcium chloride as an ion triplet in organic solvents. This macrocycle was able to extract different salts into the solvent. Additional experiments on miscibility and solubility demonstrates the complex world of multi layer experiments

Facies characterization of carbonates by use of well logs, Jay Field (Smackover Formation), Santa Rita County, Florida

Eleven wells in the Jay Field were chosen for the most complete analysis of carbonate deposition according to their location in the field along a strike and two dip sections. [...] Complete suites of well logs for each of these wells were made available by Exxon, U.S.A. in Pensacola, Florida, along with several special reports from Exxon Production Research Company, Houston, Texas. All of the logs were digitized at Dresser-Atlas Petroleum Engineering Services, Houston, Texas. Only intervals corresponding to the Smackover Formation were evaluated. Up to nine curves were digitized for each well, including three porosity logs Sonic, CNL Neutron, and Density, as well as Bulk Density, the Dual Lateralog, Gamma Ray, and Spontaneous Potential Logs. The Density porosity log was not available in all wells. These curve values were put into a large data set to use for frequency crossplots. General Smackover core descriptions from all wells in the study were acquired from Core Laboratories. These, along with M.A. Ziegler's special report in 1973, and Sigsby's detailed study in 1976, were used for all initial log correlations across the field. Cross sections, a strike and two dip sections, were constructed based on the Bulk Density log response as a control log and the Gamma Ray log as a horizons marker. The Smackover section in each well was divided into intervals or zones, similar to those of Ziegler, according to these basic log characteristics and core descriptions, when available. The complete Log Analysis and Formation Evaluation Program, written by Yih Bor Chang (in progress, 1985) was used to read all the log data from the digitized tapes and to crossplot electric log response values for the studied wells. The program allows for depth shifting of logs, the editing and sorting of data, the selection of individual log curves, and the designation of specific intervals in a chosen well. The crossplotting factors P, K, A, M, and N, as defined by W. Fertl (1981), can be calculated within the program. All data points were used to best understand the "total", unedited log response from carbonate rocks. In the initial stages of this study, up to 55 of the over one hundred possible crossplots were generated for each zone within each individual single well. The crossplots were analysed for their usefulness in distinguishing different facies in the field. X and Y axis intervals and increments were adjusted where necessary. Select cross plots were then chosen for more detailed study [...]. The results of the frequency crossplots were examined for trends which might identify separate carbonate facies in the Smackover Formation solely from log crossplots. The zone, or facies, definitions were reevaluated where a large amount of scatter appeared in the crossplots of some wells. The crossplot clustering was analyzed for zone differentiation in the individual wells, and then for lateral continuity across the field along the strike and dip sections. These zones were examined for association with different facies known to exist in the Smackover Formation in the Jay ReservoirPetroleum and Geosystems Engineerin

AC losses in Bi,Pb(2223) multifilamentary wires with square cross-section

We have fabricated prototype Bi,Pb(2223)/Ag superconduting multifilamentary wires with a square cross-section. The AC losses of these wires were measured, compared with those of tapes and also compared with the theory. Wires show largely reduced AC magnetic field losses at 47 Hz, compared to those of tapes in a perpendicular magnetic field. The effects of the twist pitch and of the use of the high resisitive barriers were also investigated. The results show that the use of a twist pitch of about 10 mm is sufficient for decoupling the filaments, and that the use of very short twist pitches does not further reduce the absolute value of the AC losses. The losses in the wires are still higher than those of tapes in a parallel magnetic field, but the results show that the square or round configurations are interesting for applications where a perpendicular component of the magnetic field cannot be avoided, or for applications in rotating magnetic fields.Comment: 8 pages, 11 figures, submitted to Physica

Regulation of Oxidized Base Repair in Human Chromatin by Posttranslational Modification

Base excision repair (BER) is the major pathway for the repair of oxidized bases and apurinic/apyrimidinic (abasic; AP) sites produced by reaction with reactive oxygen/nitrogen species (ROS/RNS). These metabolites are generated spontaneously by endogenous cellular processes and also by environmental agents. Because most of these lesions are promutagenic, linked to diverse disease-associated somatic mutations, as well as heritable single nucleotide polymorphisms (SNPs) in the normal human population, their prompt repair is warranted. Impairment of repair leading to mutation, a hallmark of cancer, underscores the essentiality of BER for maintaining genome integrity in humans and other mammals. In mammals, repair of oxidized bases and other BER substrates is initiated by DNA glycosylases (DGs), which excise the damaged bases and cleave the DNA strands at the resulting AP sites, followed by sequential end processing, gap-filling DNA synthesis, and ligation. In vitro BER performed with naked DNA substrates has been extensively studied, which delineates its basic mechanistic steps and subpathways. However, recent interest is directed to unraveling BER in cell chromatin, including its regulation via posttranslational modifications (PTMs), which occurs possibly in concert with nucleosome remodeling. Emerging reports on various PTMs of BER enzymes indicate that the PTMs, while dispensable for the enzymatic activity, regulate overall repair by modulating interactions with other repair proteins and chromatin factors, assembly of BER complexes, as well as turnover of the proteins, and may ultimately dictate the cellular phenotype. Here, we discuss recent advances in the BER field by reviewing the PTMs and how they regulate BER in chromatin