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An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The isolable 16-electron half-sandwich Os complex [OsBr(η5-C5Me5)(PiPr3)] has been synthesized and structurally characterized. This unsaturated complex binds N2 reversibly at low temperature as determined by IR and multinuclear NMR spectroscopy. The reactions of the title complex with CO, H2, PhSiH3, and its thermolysis in C6H6 are reported.
2 Abstract: Two contrasting experimental descriptions of P1 plasmid replication during the cell cycle of Escherichia coli have been described. One set of results led to the proposal that replication of P1 plasmid occurs at a specific time during the cell cycle over a wide range of growth rates and follows rules similar to that governing bacterial chromosome replication. Experiments supporting this proposal utilized membrane-elution experiments, radioactive double-labeling of DNA and scintillation counting of purified plasmids. An alternative experimental description of P1 plasmid replication during the cell cycle, also based on membrane-elut ion methodology but measuring radioactivity incorporated into plasmid DNA by autoradiograp hy and scanning of films, proposed that P1 plasmid replicates at all stages of the cell cycle in rapidly growing cells, but with a slight periodicity or increase in P1 replication probability within the cell cycle of slower growing cells. These discordant experimental results are analyzed. It is concluded that the direct double-label counting approach is to be preferred, as the results are consistent with a large number of experiments, are supported by theoretical considerations and yield a unified view of plasmid replication over a wide range of growth rates. Theoretical ramifications of each view of P1 plasmid replication-cycle-dependent and cycle-independent are compared. An analysis of P1 plasmid segregation is also presented.
The richness and versatility of biological systems make them ideally suited to solve some of the world's most significant challenges, such as converting cheap, renewable resources into energy-rich molecules; producing high-quality, inexpensive drugs to fight disease; and remediating polluted sites. Over the years, significant strides have been made in engineering microorganisms to produce fuels, bulk chemicals, and valuable drugs from inexpensive starting materials; to detect and degrade nerve agents as well as less toxic organic pollutants; and to accumulate metals and reduce radionuclides. The components needed to engineer the chemistry inside a microbial cell are significantly different from those commonly used to overproduce pharmaceutical proteins. Synthetic biology has had and will continue to have a significant impact on the development of these components to engineer cellular metabolism and microbial chassis to host the chemistry. The ready availability of more well-characterized gene expression components and hosts for chemical synthesis, standards for the connection of these components to make larger functioning devices, computer-aided design software, and debugging tools for biological designs will decrease both the time and the support needed to construct these designs. Some of the most important tools for engineering bacterial metabolism and their use for production of the antimalarial drug artemisinin are reviewed.
The evolution of the shape of surface cracks in sensitized Type 304 SS in Boiling Water Reactor primary coolant at 288 o C was explored as a function of the corrosion potential and stress intensity using the Coupled Environment Fracture Model (CEFM). The revised CEFM that incorporates Shoji’s model for calculating the crack tip strain rate and more advanced expressions for estimating the stress intensity factor for semi-elliptical surface cracks provides more accurate prediction of the dependence of the crack growth rate on stress intensity factor and offers an alternative explanation for the development of semi-elliptical cracks than that provided by fracture mechanics. The evolution of the shape of surface cracks depends strongly upon environmental variables, such as the corrosion potential, predicting that the minor axis of the ellipse should be oriented perpendicular to the surface due to the dependence of the crack growth rate on the electrochemical crack length.
Abstract An analogue VLSI circuit architecture for the CMOS implementation of cellular neural networks (CNNs) is presented. It is based exclusively on the use of small capacitors and operational transconductance amplifiers operating in continuous time. Integrated circuit implementations of this architecture are very well suited for processing applications requiring large array size and high speed. We describe a systematic design approach for those circuits and present the design, fabrication and testing of two chips. These chips are used for connected component detection applications and are the first working integrated circuit implementation of a CNN. They contain 2000 transistors and have been fabricated using 2 μm CMOS technology. the density is 32 cells per square millimetre of silicon and the time constant of the processing is of the order of 10 −7 s. Experimental results of static and dynamic tests are given, including a complete image‐processing example.
Pour explorer les changements institutionnels qui ont augmente l'etendue de la polarisation sociale et economique dans les dernieres decennies, l'A. explore quatre differentes logiques de polarisation : macrosociale, economique, politique et spatiale. Puis il en trace les consequences pour la pauperisation croissante des plus pauvres, ce qui en fait le groupe le plus souvent decrit comme underclass. Mais, comme Ingham, il souligne qu'une polarisation implique deux poles et ne doit pas etre vue en relation avec le seul groupe des pauvres. En depit d'une experience similaire de croissance des inegalites depuis la fin des annees 1970, (et, dans le cas britannique, depuis l'application des politiques neoliberales) l'A. estime qu'un parallele direct ne peut etre dresse entre les experiences americaines et europeennes, en particulier en ce qui concerne la criminalisation de la pauvrete aux Etats-Unis. Il evalue les differentes strategies qui ont ete proposees pour stopper la polarisation sociale et ses effets negatifs, soutenant que la solution a la deterioration des chances sociales des groupes situes au bas de l'echelle sociale reside dans l'instauration d'une forme de revenu minimum qui effectue une redistribution des revenus depuis les classes privilegiees
