7,626 research outputs found

    High surface area, emulsion-templated carbon foams by activation of polyHIPEs derived from Pickering emulsions.

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    Carbon foams displaying hierarchical porosity and excellent surface areas of >1400 m2/g can be produced by the activation of macroporous poly(divinylbenzene). Poly(divinylbenzene) was synthesized from the polymerization of the continuous, but minority, phase of a simple high internal phase Pickering emulsion. By the addition of KOH, chemical activation of the materials is induced during carbonization, producing Pickering-emulsion templated carbon foams, or carboHIPEs, with tailorable macropore diameters and surface areas almost triple that of those previously reported. The retention of the customizable, macroporous open-cell structure of the poly(divinylbenzene) precursor and the production of a large degree of microporosity during activation leads to tailorable carboHIPEs with excellent surface areas

    A Laboratory Soil-Contact Decay Test: An Accelerated Method To Determine Durability of Treated Wood Shakes

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    In this study, cross sections of preservative-treated shakes were evaluated in soil-contact decay tests using Gleophyllum trabeum. The number of preservatives by species combinations used allowed evaluation of procedural aspects of this method. We conclude that the soil-contact decay test is a good tool for an accelerated evaluation of the durability of treated shakes. Experimental designs need to be structured so that each wood species can be analyzed separately. Interpretation of results requires consideration of both the distribution and median or mean of weight loss data for each treatment. Levels of retention should be well dispersed so that the effects of retention upon distribution of weight loss data for individual treatments can be determined. Selection of a sufficient sample size to represent the variation within the population of each wood species by treatment combination is judged to be more important than duration of the incubation period in excess of 12 weeks. Stated differently, a rigorous experimental design permits discrimination of major differences without a need to achieve a weight loss of 50% in untreated materials. Wood species utilized in this study were western hemlock (Tsuga heterophylla (Raf.) Sarg.), Pacific silver fir (Abies amabilis Dougl. ex Forbes), grand fir (Abies grandis Dougl. ex D. Don Lindl.), western white pine (Pinus monticola Dougl. ex D. Don), southern pine spp., and red alder (Alnus rubra Bong.)

    The Reconstruction Problem and Weak Quantum Values

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    Quantum Mechanical weak values are an interference effect measured by the cross-Wigner transform W({\phi},{\psi}) of the post-and preselected states, leading to a complex quasi-distribution {\rho}_{{\phi},{\psi}}(x,p) on phase space. We show that the knowledge of {\rho}_{{\phi},{\psi}}(z) and of one of the two functions {\phi},{\psi} unambiguously determines the other, thus generalizing a recent reconstruction result of Lundeen and his collaborators.Comment: To appear in J.Phys.: Math. Theo

    Comparison of prefrontal atrophy and episodic memory performance in dysexecutive Alzheimer’s disease and behavioural-variant frontotemporal dementia

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    Alzheimer’s disease (AD) sometimes presents with prominent executive dysfunction and associated prefrontal cortex atrophy. The impact of such executive deficits on episodic memory performance as well as their neural correlates in AD, however, remains unclear. The aim of the current study was to investigate episodic memory and brain atrophy in AD patients with relatively spared executive functioning (SEF-AD; n = 12) and AD patients with relatively impaired executive functioning (IEF-AD; n = 23). We also compared the AD subgroups with a group of behavioral-variant frontotemporal dementia patients (bvFTD; n = 22), who typically exhibit significant executive deficits, and age-matched healthy controls (n = 38). On cognitive testing, the three patient groups showed comparable memory profiles on standard episodic memory tests, with significant impairment relative to controls. Voxel-based morphometry analyses revealed extensive prefrontal and medial temporal lobe atrophy in IEF-AD and bvFTD, whereas this was limited to the middle frontal gyrus and hippocampus in SEF-AD. Moreover, the additional prefrontal atrophy in IEF-AD and bvFTD correlated with memory performance, whereas this was not the case for SEF-AD. These findings indicate that IEF-AD patients show prefrontal atrophy in regions similar to bvFTD, and suggest that this contributes to episodic memory performance. This has implications for the differential diagnosis of bvFTD and subtypes of AD

    Ferromagnetic to spin glass cross over in (La,Tb)_{2/3}Ca_{1/3}MnO_{3}

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    In the series La_{2/3-x}Tb_{x}Ca_{1/3}MnO_{3}, it is known that the compositions are ferromagnetic for smaller values of x and show spin glass characteristics at larger values of x. Our studies on the magnetic properties of various compositions in the La_{2/3-x}Tb_{x}Ca_{1/3}MnO_{3} series show that the cross over from ferromagnetic to spin glass region takes place above x ~ 1/8. Also, a low temperature anomaly at 30 K, observed in the ac susceptibility curves, disappears for compositions above this critical value of x. A mixed phase region coexists in the narrow compositional range 0.1 <= x <= 0.125, indicating that the ferromagnetic to spin glass cross over is not abrupt.Comment: 5 pages, 5 figure

    Characterization of the second- and third-order nonlinear optical susceptibilities of monolayer MoS2_2 using multiphoton microscopy

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    We report second- and third-harmonic generation in monolayer MoS2_\mathrm{2} as a tool for imaging and accurately characterizing the material's nonlinear optical properties under 1560 nm excitation. Using a surface nonlinear optics treatment, we derive expressions relating experimental measurements to second- and third-order nonlinear sheet susceptibility magnitudes, obtaining values of χs(2)=2.0×1020|\chi_s^{(2)}|=2.0\times10^{-20} m2^2 V1^{-1} and for the first time for monolayer MoS2_\mathrm{2}, χs(3)=1.7×1028|\chi_s^{(3)}|=1.7\times10^{-28} m3^3 V2^{-2}. These sheet susceptibilities correspond to effective bulk nonlinear susceptibility values of χb(2)=2.9×1011|\chi_{b}^{(2)}|=2.9\times10^{-11} m V1^{-1} and χb(3)=2.4×1019|\chi_{b}^{(3)}|=2.4\times10^{-19} m2^2 V2^{-2}, accounting for the sheet thickness. Experimental comparisons between MoS2_\mathrm{2} and graphene are also performed, demonstrating \sim3.4 times stronger third-order sheet nonlinearity in monolayer MoS2_\mathrm{2}, highlighting the material's potential for nonlinear photonics in the telecommunications C band.Comment: Accepted by 2D Materials, 28th Oct 201

    Updates from the Regional Human Rights Systems

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    Estimation of individual beneficial and adverse effects of intensive glucose control for patients with type 2 diabetes

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    AIMS/HYPOTHESIS: Intensive glucose control reduces the risk of vascular complications while increasing the risk of severe hypoglycaemia at a group level. We sought to estimate individual beneficial and adverse effects of intensive glucose control in patients with type 2 diabetes. METHODS: We performed a post hoc analysis of the Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation (ADVANCE) trial, a randomised controlled trial evaluating standard vs intensive glucose control (HbA1c target ≤6.5% [48 mmol/mol]). In 11,140 participants, we estimated the individual 5 year absolute risk reduction (ARR) for the composite outcome of major micro- and macrovascular events and absolute risk increase (ARI) for severe hypoglycaemia for intensive vs standard glucose control. Predictions were based on competing risks models including clinical characteristics and randomised treatment. RESULTS: Based on these models, 76% of patients had a substantial estimated 5 year ARR for major vascular events (>1%, 5 year number-needed-to-benefit [NNTB5] 200). Similarly, 36% of patients had a substantial estimated ARI for severe hypoglycaemia (5 year number-needed-to-harm [NNTH5] 200). When assigning similar or half the weight to severe hypoglycaemia compared with a major vascular event, net benefit was positive in 85% or 99% of patients, respectively. Limiting intensive treatment to the 85% patient subgroup had no significant effect on the overall incidence of major vascular events and severe hypoglycaemia compared with treating all patients. CONCLUSIONS/INTERPRETATION: Taking account of the effects of intensive glucose control on major micro- and macrovascular events and severe hypoglycaemia for individual patients, the estimated net benefit was positive in the majority of the participants in the ADVANCE trial. The estimated individual effects can inform treatment decisions once individual weights assigned to positive and adverse effects have been specified. TRIAL REGISTRATION: ClinicalTrials.gov NCT00145925
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