2,267 research outputs found

    A Theoretical Search For An Electronic Spectrum Of The He-beo Complex

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    The surprisingly high dissociation energy of the He-Be bond in the He-BeO complex was first reported 25 years ago.\footnote{W. Koch, J. R. Collins and G. Frenking, \textit{Chem. Phys. Lett.} 1986, \textbf{132} 330-333.} Following which, a number of theoretical studies have investigated similar closed shell helium containing complexes. However, despite these investigations, a complex containing a strong He-X bond has thus far eluded experimental detection. In this work, potential energy surfaces of electronically excited states of the He-BeO complex have been calculated employing high level CASSCF+MRCI+Q methodologies and utilizing extended basis sets. Several excited states show strong interactions between helium and BeO lying in Franck-Condon accessible windows of electronic transitions arising from the vibrationless electronic ground state. It is hoped that the conclusions of this study will result in the observation an electronic spectrum of this long hypothesized strongly bound complex in the near future

    Cloud as a Game-Changing Business Strategy

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    Infective Endocarditis in Low- And Middle-Income Countries

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    Infective endocarditis (IE) is a rare, life-threatening disease with a mortality rate of upto 25% and significant debilitating morbidities. Although much has been reported on contemporary IE in high income countries, conclusions on the state of IE in low and middle income countries (LMICs) are based on studies conducted before the year 2000. Furthermore, unique challenges in the diagnosis and management of IE persist in LMICs. This article is a review of IE studies conducted in LMICs documenting clinical experiences from the year 2000 to present. We present the causes of IE, management of patients with IE and the prevailing challenges in diagnosis and treatment of IE in LMICs

    An analysis of the shape of the spine and torso in those with and without scoliosis

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    Abstract The shape of the spine and torso are central to the management of scoliosis, a condition with a three-dimensional rotation in the spine associated with asymmetry of the torso. It is not clear what the variability in shape and symmetry of both the spine and the torso is in a non-scoliotic cohort. Using ISIS2 surface topography, the torsos of a non-scoliotic cohort were measured yearly for seven years, allowing true longitudinal analysis. Parameters of growth and symmetry were measured and analysed to demonstrate the variability of normal shape during the adolescent growth spurt using linear mixed effect modelling and data ellipses, examining for the effects of age and sex. This demonstrated a range of normal shape and the differences between males and females. The non-scoliotic shape was then analysed alongside a group of matched pre and post-operative scoliotic subjects using data ellipses and Procrustes analysis. This showed that scoliosis increases the asymmetry of the spine and torso as an amplification of the variability in the non-scoliotic cohort. This asymmetry is reduced by surgery in nearly all parameters measured. However, some appreciable differences remain when compared to the non-scoliotic cohort

    Resonance-enhanced multiphoton ionization (REMPI) spectroscopy of p-chlorofluorobenzene

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    The S1 ← S0 (A ~ 1B2 ← X~ 1A1) electronic transition of para-chlorofluorobenzene has been investigated using resonance-enhanced multiphoton ionization (REMPI) spectroscopy. Assignment of the vibrational structure has been achieved by comparison with corresponding spectra of related molecules, via quantum chemical calculations, and via shifts in bands between the spectra of the 35Cl and 37Cl isotopologues. In addition, we have also partially reassigned a previously-published spectrum of para-dichlorobenzene

    Protocol: High-throughput and quantitative assays of auxin and auxin precursors from minute tissue samples

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    Background: The plant hormone auxin, indole-3-acetic acid (IAA), plays important roles in plant growth and development. The signaling response to IAA is largely dependent on the local concentration of IAA, and this concentration is regulated by multiple mechanisms in plants. Therefore, the precise quantification of local IAA concentration provides insights into the regulation of IAA and its biological roles. Meanwhile, pathways and genes involved in IAA biosynthesis are not fully understood, so it is necessary to analyze the production of IAA at the metabolite level for unbiased studies of IAA biosynthesis. Results: We have developed high-throughput methods to quantify plant endogenous IAA and its biosynthetic precursors including indole, tryptophan, indole-3-pyruvic acid (IPyA), and indole-3-butyric acid (IBA). The protocol starts with homogenizing plant tissues with stable-labeled internal standards added, followed by analyte purification using solid phase extraction (SPE) tips and analyte derivatization. The derivatized analytes are finally analyzed by selected reaction monitoring on a gas chromatograph-mass spectrometer (GC-MS/MS) to determine the precise abundance of analytes. The amount of plant tissue required for the assay is small (typically 2–10 mg fresh weight), and the use of SPE tips is simple and convenient, which allows preparation of large sets of samples within reasonable time periods. Conclusions: The SPE tips and GC-MS/MS based method enables high-throughput and accurate quantification of IAA and its biosynthetic precursors from minute plant tissue samples. The protocol can be used for measurement of these endogenous compounds using isotope dilution, and it can also be applied to analyze IAA biosynthesis and biosynthetic pathways using stable isotope labeling. The method will potentially advance knowledge of the role and regulation of IAA
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