6,263 research outputs found

    Ultrathin Amorphous Silica Membrane Enhances Proton Transfer across Solid-to-Solid Interfaces of Stacked Metal Oxide Nanolayers while Blocking Oxygen

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    A large jump of proton transfer rates across solid-to-solid interfaces by inserting an ultrathin amorphous silica layer into stacked metal oxide nanolayers is discovered using electrochemical impedance spectroscopy and Fourier-transform infrared reflection absorption spectroscopy (FT-IRRAS). The triple stacked nanolayers of Co3O4, SiO2, and TiO2 prepared by atomic layer deposition (ALD) enable a proton flux of 2400 ± 60 s−1 nm−2 (pH 4, room temperature), while a single TiO2 (5 nm) layer exhibits a threefold lower flux of 830 s−1 nm−2. Based on FT-IRRAS measurements, this remarkable enhancement is proposed to originate from the sandwiched silica layer forming interfacial SiOTi and SiOCo linkages to TiO2 and Co3O4 nanolayers, respectively, with the O bridges providing fast H+ hopping pathways across the solid-to-solid interfaces. Together with the complete O2 impermeability of a 2 nm ALD-grown SiO2 layer, the high flux for proton transport across multi-stack metal oxide layers opens up the integration of incompatible catalytic environments to form functional nanoscale assemblies such as artificial photosystems for CO2 reduction by H2O

    Methodologies for self-organising systems:a SPEM approach

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    We define ’SPEM fragments’ of five methods for developing self-organising multi-agent systems. Self-organising traffic lights controllers provide an application scenario

    Topische Therapie bei chronisch-entzĂŒndlichen Darmerkrankungen: Ein hĂ€ufig unterschĂ€tzter Therapiebaustein

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    Zusammenfassung: Die Inzidenz und PrĂ€valenz der Colitis ulcerosa nimmt sowohl in westlichen LĂ€ndern als auch in EntwicklungslĂ€ndern zu. Grundstein der Behandlung ist die Anwendung von Aminosalicylaten (5-ASA). Alternativ können auch steroidhaltige topische Therapien eingesetzt werden. HĂ€ufig werden 5-ASA-PrĂ€parate nur peroral verabreicht, obschon insbesondere bei Proktitis und linksseitiger Kolitis topische (oder rektale) 5-ASA-PrĂ€parate sogar effizienter sind als perorale/systemische. Dies gilt sowohl fĂŒr die Remissionsinduktion wie auch fĂŒr die remissionserhaltende Therapie. Zahlreiche Untersuchungen in Kohorten oder grĂ¶ĂŸeren Behandlungszentren zeigen, dass topische Therapien zu selten eingesetzt werden. Insbesondere bei der ausgedehnten Kolitis sollten perorale und topische Therapien kombiniert Anwendung finden. In diesem Übersichtsartikel fassen wir die Evidenz der topischen Therapie bei der Colitis ulcerosa mit 5-ASA und Steroiden zusammen. Damit kann die Therapie optimiert und die Akzeptanz einer topischen Therapie bei den Patienten verbessert werden. Diese ist nach entsprechender AufklĂ€rung höher als generell vermutet wird. Nur bei schweren KolitisverlĂ€ufen hat eine topische Therapie keinen Stellenwert, da sie zum einen bei hĂ€ufigen Darmentleerungen nicht ausreichend wirksam wĂ€re und zum anderen von den Patienten schlecht toleriert wird. Die Evidenz fĂŒr die Anwendung topischer Therapien bei Morbus Crohn ist unzureichen

    GLADE: A galaxy catalogue for multimessenger searches in the advanced gravitational-wave detector era

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    We introduce a value-added full-sky catalogue of galaxies, named as Galaxy List for the Advanced Detector Era, or GLADE. The purpose of this catalogue is to (i) help identifications of host candidates for gravitational-wave events, (ii) support target selections for electromagnetic follow-up observations of gravitational-wave candidates, (iii) provide input data on the matter distribution of the local Universe for astrophysical or cosmological simulations, and (iv) help identifications of host candidates for poorly localized electromagnetic transients, such as gamma-ray bursts observed with the InterPlanetary Network. Both being potential hosts of astrophysical sources of gravitational waves, GLADE includes inactive and active galaxies as well. GLADE was constructed by cross-matching and combining data from five separate (but not independent) astronomical catalogues: GWGC, 2MPZ, 2MASS XSC, HyperLEDA, and SDSS-DR12Q. GLADE is complete up to dL=37+3−4Mpc in terms of the cumulative B-band luminosity of galaxies within luminosity distance dL, and contains all of the brightest galaxies giving half of the total B-band luminosity up to dL=91Mpc. As B-band luminosity is expected to be a tracer of binary neutron star mergers (currently the prime targets of joint GW+EM detections), our completeness measures can be used as estimations of completeness for containing all binary neutron star merger hosts in the local Universe

    The non-destructive study of museums objects by means of neutrons imaging methods and results of investigations

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    Based on experience from many kinds of investigations with neutron imaging methods (radiography, tomography, time-dependent studies) and in comparison to conventional X-ray methods, the authors discuss the potential of future improved studies for cultural-heritage purposes. Whereas the focus of the paper is on the imaging aspect, other established techniques as neutron activation analysis (NAA), prompt gamma activation analysis (PGAA), neutron-induced autoradiography and neutron scattering are mentioned too. Although a great potential for studies similar to those described in the paper exists, a considerable effort is needed to define the best-suited methods for the dedicated cultural historical request. A real barrier between the experts at large research facilities (as, e.g., neutron sources are) and the partners from the museums side has to be overcome in order to solve the problems. A joint European approach will help in this respect

    Granite-hosted gold mineralization in the Midlands greenstone belt: a new type of low-grade gold deposit in Zimbabwe

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    In 1992, the Ford gold deposit was rediscovered during field work in the Kwekwe district near the Indarama mine, approximately 200 km southwest of Harare, Zimbabwe. Based on diamond drilling and open pit operations, estimated ore reserves are at least 3 Mt with an average gold content of 2.5 g/t. The gold deposit is located within a porphyritic granite dike with a thickness of 20–50 m, striking 800 m NNW-SSE. It dips 60–70° to the NE and intrudes a volcano-sedimentary sequence of tholeiitic basalts, acid volcanics, and banded iron formations of the Bulawayan Group (2900–2700 Ma). The intrusion of the dike occurred at 2541 ± 17 Ma (Pb/Pb step leaching technique) within a second order structure and is related to displacement along transcrustal deformation zones such as the Sherwood- and Taba-Mali deformation zones. Gold mineralization is confined to the s-shaped part of the dike intrusion. At the present stage of mining, the deposit is characterized by the absence of major veins, the occurrence of disseminated pyrite throughout the orebody, and a distinct alteration pattern comparable to that of porphyry copper deposits. The central zone of the dike shows a typical K-feldspar-albite-sericite-pyrite (±biotite?) alteration, followed by a narrow external propylitic zone. Native gold with an average Ag content of 5 wt.% and a grain size of 5–100 ÎŒm is rare and occurs within pyrite and secondary K-feldspar. Sulphide mineral separates of pyrite and minor arsenopyrite probably contain invisible gold (up to 120 ppm) amenable to cyanidation. Anomalously high gold values of ∌7 ppm have been found in the transition between the K-feldspar-albite-sericite-pyrite alteration and the propylitic zone, indicating that the mineralizing fluids have experienced major physico-chemical changes in the transition zone. The regional tectonic position of the orebody suggests that the emplacement of the granite and the gold mineralization are structurally controlled. The Pb isotope composition of several leachates of pyrite indicate isotope disequilibrium with magmatic minerals and point to a contamination of the mineralizing fluid by Pb from older (sedimentary?) sources. Stable isotope geochemistry of sulphides and carbonates as well as the metallogeny of the deposit compare to shear-zone hosted gold mineralization in the Kwekwe district, for which a deep crustal origin has been discussed. Although this study documents contrasting evidence for a porphyry-gold versus a shear-zone type of mineralization, it is suggested that gold-bearing fluids were syntectonically introduced into a ductile shear zone within the granite dike either during cooling of the intrusion or later in Archaean or early Proterozoic times

    Post-Transplant Diabetes Mellitus in Renal Allograft Recipients: A Matched-Pair Control Study

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    The incidence of post-transplant diabetes mellitus was evaluated retrospectively in 901 consecutive renal transplant recipients. Thirty-two (3.6%) patients developed diabetes mellitus requiring drug therapy. 18 of 32 became hyperglycaemic within 3 months of transplantation. Post-transplant diabetes mellitus occurred in 24 of 628 (3.8%) patients treated with conventional therapy consisting in azathioprine and prednisone, and in 8 of 273 (2.9%) patients receiving cyclosporin A (CsA) in addition (triple therapy). To identify predisposing factors 32 nondiabetic patients matched for age, sex, number of graft, immunosuppressive protocol, and graft function at onset of diabetes were used as case controls. Thirteen of 32 patients with diabetes mellitus and 5 of 32 control patients had abnormal glucose tolerance pretransplant (P<0.025). HLA-B8 was significantly more frequent in patients with post-transplant diabetes mellitus than in control patients (9 of 29 vs 2 of 31, (P<0.02). Twelve (38%) patients became diabetic during or immediately after anti-rejection therapy with intravenous pulse prednisone. Four diabetic patients experienced chronic pancreatitis pre-transplant. Family history of diabetes mellitus, bodyweight, number of rejection episodes, and immunosuppressive drug doses were similar in both groups. Actuarial patient and graft survival was not significantly different in diabetic patients and controls, although 10-year data tended to be better in controls. Thus, post-transplant diabetes mellitus was not a frequent complication in patients sometimes predisposed by an impaired glucose tolerance pre-transplant and was triggered by pulse prednisone therapy in 38
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