1,050 research outputs found

    The influence of molecular rotation on the direct subsurface absorption of H2 on Pd(111)

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    Within the generalized gradient approximation (GGA) of density functional theory (DFT) we have calculated a three-dimensional (3D) potential energy surface (PES) including an angular degree of freedom for a

    Evaluation of soil phosphate residues by plant uptake and extractable phosphorus

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    Non-Peer ReviewedResidual phosphate from fertilizer P or manure seemed to accumulate mainly as octocalcium phosphate (OCP) in 23 alkaline and calcareous soils of eastern Colorado. These soils contained 37 to 162 ppm NaHCO3-soluble P. Phosphorus removed by cropping varied between 58 and 275 ppm with 5 to 8 crops before P deficiency re-appeared. Phosphorus uptake was highly correlated with NaHCO3-soluble P (four successive extracts), resin-extractable P, and labile P by 32P isotopic dilution. All of the OCP dissolved during cropping. This material seems to have a very high availability coefficient for plants. Accumulation of fertilizer P residues in this form would appear to be beneficial since this P is potentially all available to crops. Therefore, methods for estimating the amount of OCP in soils should be useful

    An assessment of key risk factors for surgical site infection in patients undergoing surgery for spinal metastases

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    Objectives This study aimed to determine the rate of surgical site infection (SSI) in patients undergoing surgery for spinal metastases, and identify key risk factors for SSI among this patient group. Methods A retrospective case note review was undertaken in 152 adult patients being treated at a single specialist centre for spinal surgery. Results Overall SSI rate was 11.2% per patients (9.7% per procedure). An increase in the risk of SSI was observed when surgery involved a greater number of vertebral levels (odds ratio 1.26, P=0.019) when controlling for primary spinal region. Controlling for the number of spinal levels, the odds of SSI increased by a factor of 5.6 (P=0.103) when the primary surgical region was thoracic, as opposed to cervical or lumbar. Conclusions In conclusion, surgery associated with multiple vertebral levels for treatment of spinal metastases, particularly of the thoracic spine, is associated with increased risk of SSI

    Roughness Analysis In Strained Silicon-on-insulator Wires And Films

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    Strained silicon is used to enhance performance in state-of-the-art CMOS. Under device operating conditions, the effect of strain is to reduce the carrier scattering at the channel by a smoother semiconductor surface. This has never been completely understood. This paper gives first evidence of the variation in surface roughness under realistic strained conditions. At the nanoscale, the SiO2/Si interface roughness is dependent on the scale of observation (self-affinity). To date, there is no experimental study of the SiO2/Si interface roughness scaling with strain. This work presents the effect of uniaxial and biaxial strains on the surface roughness of strained silicon-on-insulator films and wires using atomic force microscopy. Levels of strain ranging from 0% to 2.3%, encompassing those used in present CMOS devices have been investigated. It is shown that the silicon surface is affected by uniaxial and biaxial strains differently. Three surface roughness parameters have been analyzed: root mean square roughness, correlation length, and the Hurst exponent, which is used to describe the scaling behavior of a self-affine surface. The results show that the root mean square roughness decreases (up to ∼ 40%) with increasing tensile strain, whereas the correlation length increases (up to ∼ 63nm/%) with increasing tensile strain. The Hurst exponent also varies with strain and with the undulation wavelength regime (between ∼ 0.8 and 0.2). This dependency explains why some models used to determine the carrier mobility from experiments fit the data better with a Gaussian form, whereas other models fit the data better with an exponential form.11612EPSRC; Engineering and Physical Sciences Research CouncilSong, Y., Zhou, H., Xu, Q., Luo, J., Yin, H., Yan, J., Zhong, H., (2011) J. Electron. Mater., 40, p. 1584Lee, M.L., Fitzgerald, E.A., Bulsara, M.T., Currie, M.T., Lochtefeld, A., (2005) J. Appl. 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    Characterizing Soil Fertility by Ion Diffusive Flux Measurements

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    The general acceptance of diffusion as a rate-limiting step in transferring ions to plant roots was considered in characterizing soil fertility. Soil ion diffusive flux measurements to an exchange resin were measured with two soil: resin cells, one with untreated soil, the other with the same soil fertilized with P, K, and Cl. The P, K, and Cl that diffused to the resin of each cell was extracted and determined. Using only these measurements and some simplifying assumptions of diffusion theory, calculations were made of the soil's P and K solution concentration, adsorbed concentration, a capacity factor, transmission factor, and quantity of fertilizer needed to attain any desired flux. Excellent to fair correlations existed between these calculated values and traditionally measured chemical quantities. Plant uptake of P and K was generally well correlated with diffusive flux measurements as well as traditional chemical measurements
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