13,640 research outputs found

    A comparison of the physical and chemical composition of UK waste streams based on hypothetical compound structure

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    The suitability and effectiveness of a waste treatment process or strategy depends upon a waste stream’s physical and chemical composition. Chemical properties of UK waste streams, particularly MSW, are limited while physical properties are better documented. Consequently this presents a degree of uncertainty with the waste’s properties, manifesting itself as financial risk in the investment of new treatment or disposal plant. To mitigate this uncertainty, a number of UK waste surveys have been reviewed to determine if there is significant difference in the calorific value between waste streams. Ultimate and proximate analysis data from a number of sources have been collected and used to approximate the chemical composition of each waste fraction. To facilitate the comparison of each waste stream, a hypothetical compound of the form C6HaOb has been determined for each. Based on this analysis, all UK waste streams share the hypothetical formula C6H10O3, indicating that on a dry basis, the composition of waste in the UK is fairly consistent. Monte Carlo analysis of the hypothetical compound structure revealed that for both household and civic amenity waste streams, the hydrogen and oxygen content only deviate slightly from the mean values. Since MSW is predominantly comprised of household and civic amenity waste, the hypothetical compound C6H10O3 can be used to approximate UK MSW

    Temperature dependence of the average electron-hole pair creation energy in Al0.8Ga0.2As

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    The temperature dependence of the average energy consumed in the creation of an electron-hole pair in the wide bandgap compound semiconductor Al 0.8Ga0.2As is reported following X-ray measurements made using an Al0.8Ga0.2As photodiode diode coupled to a low-noise charge-sensitive preamplifier operating in spectroscopic photon counting mode. The temperature dependence is reported over the range of 261 K-342 K and is found to be best represented by the equation ε AlGaAs 7.327-0.0077 T, where εAlGaAs is the average electron-hole pair creation energy in eV and T is the temperature in K. © 2013 © 2013 Author(s)

    Relationship of blood pressure, antihypertensive therapy, and outcome in ischemic stroke treated with intravenous thrombolysis: retrospective analysis from Safe Implementation of Thrombolysis in Stroke-International Stroke Thrombolysis Register (SITS-ISTR)

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    <p><b>Background and Purpose:</b> The optimal management of blood pressure (BP) in acute stroke remains unclear. For ischemic stroke treated with intravenous thrombolysis, current guidelines suggest pharmacological intervention if systolic BP exceeds 180 mm Hg. We determined retrospectively the association of BP and antihypertensive therapy with clinical outcomes after stroke thrombolysis.</p> <p><b>Methods:</b> The SITS thrombolysis register prospectively recorded 11 080 treatments from 2002 to 2006. BP values were recorded at baseline, 2 hours, and 24 hours after thrombolysis. Outcomes were symptomatic (National Institutes of Health Stroke Scale score deterioration ≥4) intracerebral hemorrhage Type 2, mortality, and independence at (modified Rankin Score 0 to 2) 3 months. Patients were categorized by history of hypertension and antihypertensive therapy within 7 days after thrombolysis: Group 1, hypertensive treated with antihypertensives (n=5612); Group 2, hypertensive withholding antihypertensives (n=1573); Group 3, without history of hypertension treated with antihypertensives (n=995); and Group 4, without history of hypertension not treated with antihypertensives (n=2632). For 268 (2.4%) patients, these data were missing. Average systolic BP 2 to 24 hours after thrombolysis was categorized by 10-mm Hg intervals with 100 to 140 used as a reference.</p> <p><b>Results:</b> In multivariable analysis, high systolic BP 2 to 24 hours after thrombolysis as a continuous variable was associated with worse outcome (P<0.001) and as a categorical variable had a linear association with symptomatic hemorrhage and a U-shaped association with mortality and independence with systolic BP 141 to 150 mm Hg associated with most favorable outcomes. OR (95% CI) from multivariable analysis showed no difference in symptomatic hemorrhage (1.09 [0.83 to 1.51]; P=0.58) and independence (1.03 [0.93 to 1.10]; P=0.80) but lower mortality (0.82 [0.73 to 0.92]; P=0.0007) for Group 1 compared with Group 4. Group 2 had a higher symptomatic hemorrhage (1.86 [1.34 to 2.68]; P=0.0004) and mortality (1.62 [1.41 to 1.85]; P<0.0001) and lower independence (0.89 [0.80 to 0.99]; P=0.04) compared with Group 4. Group 3 had similar results as Group 1.</p> <p><b>Conclusions:</b> There is a strong association of high systolic BP after thrombolysis with poor outcome. Withholding antihypertensive therapy up to 7 days in patients with a history of hypertension was associated with worse outcome, whereas initiation of antihypertensive therapy in newly recognized moderate hypertension was associated with a favorable outcome.</p&gt

    Actions of Agonists, Fipronil and Ivermectin on the Predominant In Vivo Splice and Edit Variant (RDLbd, I/V) of the Drosophila GABA Receptor Expressed in Xenopus laevis Oocytes

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    Ionotropic GABA receptors are the targets for several classes of insecticides. One of the most widely-studied insect GABA receptors is RDL (resistance to dieldrin), originally isolated from Drosophila melanogaster. RDL undergoes alternative splicing and RNA editing, which influence the potency of GABA. Most work has focussed on minority isoforms. Here, we report the first characterisation of the predominant native splice variant and RNA edit, combining functional characterisation with molecular modelling of the agonist-binding region. The relative order of agonist potency is GABA> muscimol> TACA> β-alanine. The I/V edit does not alter the potency of GABA compared to RDLbd. Docking calculations suggest that these agonists bind and activate RDLbdI/V through a similar binding mode. TACA and β-alanine are predicted to bind with lower affinity than GABA, potentially explaining their lower potency, whereas the lower potency of muscimol and isoguvacine cannot be explained structurally from the docking calculations. The A301S (resistance to dieldrin) mutation reduced the potency of antagonists picrotoxin, fipronil and pyrafluprole but the I/V edit had no measurable effect. Ivermectin suppressed responses to GABA of RDLbdI/V, RDLbd and RDLbdI/VA301S. The dieldrin resistant variant also showed reduced sensitivity to Ivermectin. This study of a highly abundant insect GABA receptor isoform will help the design of new insecticides

    Nodal superconducting gap structure in the quasi-one-dimensional Cs2_2Cr3_3As3_3 investigated using μ\muSR measurements

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    The superconducting ground state of the newly discovered superconductor Cs2_2Cr3_3As3_3 with a quasi-one-dimensional crystal structure (TcT_{\bf c}\sim 2.1(1) K) has been investigated using magnetization and muon-spin relaxation or rotation (μ\muSR), both zero-field (ZF) and transverse-field (TF), measurements. Our ZF μ\muSR measurements reveal the presence of spin fluctuations below 4 K and the ZF relaxation rate (λ\lambda) shows enhancement below TcT_{\bf c}\sim 2.1 K, which might indicate that the superconducting state is unconventional. This observation suggests that the electrons are paired via unconventional channels such as spin fluctuations, as proposed on the basis of theoretical models. Our analysis of the TF μ\muSR results shows that the temperature dependence of the superfluid density is fitted better with a nodal gap structure than an isotropic s-wave model for the superconducting gap. The observation of a nodal gap in Cs2_2Cr3_3As3_3 is consistent with that observed in the isostructural K2_2Cr3_3As3_3 compound through TF μ\muSR measurements. Furthermore, from our TF μ\muSR study we have estimated the magnetic penetration depth λL\lambda_{\mathrm{L}}(0)(0) = 954 nm, superconducting carrier density ns=4.98×1026 n_s = 4.98 \times 10^{26}~ m3^{-3}, and carrier's effective-mass enhancement mm^* = 1.61me_{e}.Comment: 7 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:1505.0574

    Studies of the superconducting properties of Sn1-xInxTe (x=0.38 to 0.45) using muon-spin spectroscopy

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    The superconducting properties of Sn1-xInxTe (x = 0.38 to 0.45) have been studied using magnetization and muon-spin rotation or relaxation (muSR) measurements. These measurements show that the superconducting critical temperature Tc of Sn1-xInxTe increases with increasing x, reaching a maximum at around 4.8 K for x = 0.45. Zero-field muSR results indicate that time-reversal symmetry is preserved in this material. Transverse-field muon-spin rotation has been used to study the temperature dependence of the magnetic penetration depth lambda(T) in the mixed state. For all the compositions studied, lambda(T) can be well described using a single-gap s-wave BCS model. The magnetic penetration depth at zero temperature lambda(0) ranges from 500 to 580 nm. Both the superconducting gap Delta(0) at 0 K and the gap ratio Delta(0)/kBTc indicate that Sn1-xInxTe (x = 0.38 to 0.45) should be considered as a superconductor with intermediate to strong coupling.Comment: 7 pages, 6 figures, 3 table

    Antiferromagnetism at T > 500 K in the Layered Hexagonal Ruthenate SrRu2O6

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    We report an experimental and computational study of magnetic and electronic properties of the layered Ru(V) oxide SrRu2O6 (hexagonal, P-3 1m), which shows antiferromagnetic order with a N\'eel temperature of 563(2) K, among the highest for 4d oxides. Magnetic order occurs both within edge-shared octahedral sheets and between layers and is accompanied by anisotropic thermal expansivity that implies strong magnetoelastic coupling of Ru(V) centers. Electrical transport measurements using focused ion beam induced deposited contacts on a micron-scale crystallite as a function of temperature show p-type semiconductivity. The calculated electronic structure using hybrid density functional theory successfully accounts for the experimentally observed magnetic and electronic structure and Monte Carlo simulations reveals how strong intralayer as well as weaker interlayer interactions are a defining feature of the high temperature magnetic order in the material.Comment: Physical Review B 2015 accepted for publicatio

    Investigation of Superconducting Gap Structure in HfIrSi using muon spin relaxation/rotation

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    Appearance of strong spin-orbit coupling (SOC) is apparent in ternary equiatomic compounds with 5dd-electrons due to the large atomic radii of transition metals. SOC plays a significant role in the emergence of unconventional superconductivity. Here we examined the superconducting state of HfIrSi using magnetization, specific heat, zero and transverse-field (ZF/TF) muon spin relaxation/rotation (μ\muSR) measurements. Superconductivity is observed at TCT_\mathrm{C} = 3.6 K as revealed by specific heat and magnetization measurements. From the TFμ-\muSR analysis it is clear that superfluid density well described by an isotropic BCS type ss-wave gap structure. Furthermore, from TFμ-\muSR data we have also estimated the superconducting carrier density nsn_\mathrm{s} = 6.6 ×\times1026^{26}m3^{-3}, London penetration depth λL(0)\lambda_{L}(0) = 259.59 nm and effective mass mm^{*} = 1.57 mem_{e}. Our zero-field muon spin relaxation data indicate no clear sign of spontaneous internal field below TCT_\mathrm{C}, which implies that the time-reversal symmetry is preserved in HfIrSi. Theoretical investigation suggests Hf and Ir atoms hybridize strongly along the cc-axis of the lattice, which is responsible for the strong three-dimensionality of this system which screens the Coulomb interaction. As a result despite the presence of correlated dd-electrons in this system, the correlation effect is weakened, promoting electron-phonon coupling to gain importance.Comment: 8 pages, 4 figure
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