107 research outputs found

    The Cleveland Aircraft Fire Tests

    Get PDF
    On June 30 and July 1, 1966, tests were conducted to evaluate high expansion foam's ability to extend the time for which an aircraft passenger cabin environment would remain survivable during a post-crash fire. While some results tend to confirm those of similar tests, others may shed new light on the problem

    Pentadienyl Complexes of Alkali Metals: Structure and Bonding

    Get PDF
    A systematic density functional study of the structure and bonding in the alkali-metal pentadienyl complexes C5H7E (E = Li-Cs) and their analogues derived from the 2,4-dimethylpentadienyl ligand is performed. The bonding in these structures has been analyzed in some detail with reference to molecular orbital analysis, and energy partition analysis, obtained by density functional calculations. An energy decomposition analysis indicates that the electrostatic interaction is the main factor to be considered in the stabilization of the gas-phase complexes we have studied. The stability of the U-shaped minimum energy structure decreases (the potential energy surface becomes more shallow) as the metal atom gets larger. We trace this behavior to a weakening of the metal–ligand binding due to the increasing diffuseness of the metal p orbitals on going down group 1. A significant pyramidalization at the terminal carbons in the coordinate U-shaped structure correlates with the strength of the metal–ligand binding. Initial results for the structural preferences of the complexes in solution for the lithium pentadienyl complex are examined in view of contrary experimental data. There still remains plenty of work to be done in modeling metal complexes in solution, and we suggest a way forward

    CBe5E− (E = Al, Ga, In, Tl): planar pentacoordinate carbon in heptaatomic clusters

    Get PDF
    A series of clusters with the general formula CBe5E- (E = Al, Ga, In, Tl) are theoretically shown to have a planar pentacoordinate carbon atom. The structures show a simple and rigid topological framework—a planar EBe4 ring surrounding a C center, with one of the ring Be–Be bonds capped in-plane by a fifth Be atom. The system is stabilized by a network of multicenter σ bonds in which the central C atom is the acceptor, and π systems as well by which the C atom donates charge to the Be and E atoms that encircle it

    Natural Resources Research Institute Technical Report

    Get PDF
    The eight data files (seven spreadsheets and one zipped folder) mentioned in the report (Appendices B, C, E, and F) are attached to this record along with the PDF file of the report. The zipped folder contains hundreds of .jpg, .las, .pdf, .tfd, and .xls files, totaling 3.24GB of data

    Motor coordination deficits in Alpk1 mutant mice with the inserted piggyBac transposon

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>ALPK1 (α-kinase 1) is a member of an unconventional alpha-kinase family, and its biological function remains largely unknown. Here we report the phenotypic characterization of one mutant line, in which the <it>piggyBac </it>(<it>PB</it>) transposon is inserted into the <it>Alpk1 </it>gene.</p> <p>Results</p> <p>The <it>piggyBac</it>(<it>PB</it>) insertion site in mutants was mapped to the first intron of the <it>Alpk1 </it>gene, resulting in the effective disruption of the intact <it>Alpk1 </it>transcript expression. The transposon-inserted <it>Alpk1 </it>homozygous mutants (<it>Alpk1<sup>PB/PB</sup></it>) displayed severe defects in motor coordination in a series of behavioral analysis, including dowel test, hanging wire test, rotarod analysis and footprint analysis. However, the cerebellar architecture, Purkinje cell morphology and electrophysiology of the Purkinje cells appeared normal in mutants. The motor coordination deficits in the <it>Alpk1<sup>PB/PB </sup></it>mice were rescued by transgenic mice expressing the full-length <it>Alpk1</it>-coding sequence under the control of the ubiquitous expression promoter.</p> <p>Conclusions</p> <p>Our results indicate that ALPK1 plays an important role in the regulation of motor coordination. <it>Alpk1<sup>PB/PB </sup></it>mice would be a useful model to provide a clue to the better understanding of the cellular and molecular mechanisms of ALPK1 in the control of fine motor activities.</p

    Advances in Molecular Quantum Chemistry Contained in the Q-Chem 4 Program Package

    Get PDF
    A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller–Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube

    Software for the frontiers of quantum chemistry:An overview of developments in the Q-Chem 5 package

    Get PDF
    This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange–correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear–electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an “open teamware” model and an increasingly modular design

    Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

    Get PDF
    Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia

    Pregnancy in Obese Mice Protects Selectively against Visceral Adiposity and Is Associated with Increased Adipocyte Estrogen Signalling

    Get PDF
    Maternal obesity is linked with increased adverse pregnancy outcomes for both mother and child. The metabolic impact of excessive fat within the context of pregnancy is not fully understood. We used a mouse model of high fat (HF) feeding to induce maternal obesity to identify adipose tissue-mediated mechanisms driving metabolic dysfunction in pregnant and non-pregnant obese mice. As expected, chronic HF-feeding for 12 weeks preceding pregnancy increased peripheral (subcutaneous) and visceral (mesenteric) fat mass. However, unexpectedly at late gestation (E18.5) HF-fed mice exhibited a remarkable normalization of visceral but not peripheral adiposity, with a 53% reduction in non-pregnant visceral fat mass expressed as a proportion of body weight (P<0.001). In contrast, in control animals, pregnancy had no effect on visceral fat mass proportion. Obesity exaggerated glucose intolerance at mid-pregnancy (E14.5). However by E18.5, there were no differences, in glucose tolerance between obese and control mice. Transcriptomic analysis of visceral fat from HF-fed dams at E18.5 revealed reduced expression of genes involved in de novo lipogenesis (diacylglycerol O-acyltransferase 2--Dgat2) and inflammation (chemokine C-C motif ligand 20--Ccl2) and upregulation of estrogen receptor α (ERα) compared to HF non pregnant. Attenuation of adipose inflammation was functionally confirmed by a 45% reduction of CD11b+CD11c+ adipose tissue macrophages (expressed as a proportion of all stromal vascular fraction cells) in HF pregnant compared to HF non pregnant animals (P<0.001). An ERα selective agonist suppressed both de novo lipogenesis and expression of lipogenic genes in adipocytes in vitro. These data show that, in a HF model of maternal obesity, late gestation is associated with amelioration of visceral fat hypertrophy, inflammation and glucose intolerance, and suggest that these effects are mediated in part by elevated visceral adipocyte ERα signaling
    corecore