10,812 research outputs found
Internationally recognized guidelines for 'sensible' alcohol consumption: is exceeding them actually detrimental to health and social circumstances? Evidence from a population-based cohort study
No full textBackground: the health and social impact of drinking in excess of internationally recognized weekly (>21 units in men; >14 units in women) and daily (>4 units in men; >3 units in women) recommendations for ‘sensible’ alcohol intake are largely unknown.Methods: a prospective cohort study of 1551 men and women aged around 55 years in 1988 when typical alcohol consumption was recalled using a 7-day grid. An average of 3.4 years later (1990/92), study participants were re-surveyed (n = 1259; 84.7% of the target population) when they responded to nurse-administered enquiries regarding minor psychiatric morbidity, self-perceived health, hypertension, accidents, overweight/obesity and financial difficulties. Study members were followed up for mortality experience over 18 years.Results: in fully adjusted analyses, surpassing guidelines for sensible alcohol intake was associated with an increased risk of hypertension [daily guidelines only: P-value(trend): 0.012], financial problems [weekly guidelines: P-value(difference): 0.046] and, to a lesser degree, accidents [weekly guidelines: P-value(difference): 0.065]. There was no association between either indicator of alcohol intake and mortality risk.Conclusions: in the present study, there was some evidence for a detrimental effect on health and social circumstances of exceeding current internationally recognized weekly and daily guidelines for alcohol intak
A regularization approach for the analysis of X-ray solar spectra: blind tests and applications
No full textRegularized reconstruction of the differential emission measure from solar flare hard X-ray spectra
No full textEvaluation of algorithms for reconstructing electron spectra from their bremsstrahlung hard X-ray spectra
No full textPolarization dependence of the light coupling to surface plasmons in an Ag nanoparticle & Ag nanowire system
No full textPolarization dependence of the coupling of excitation light to surface plasmon polaritons (SPPs) was investigated in a Ag nanoparticle-nanowire waveguide system (a Ag nanoparticle attached to a Ag nanowire). It was found that under the illumination of excitation light on the nanoparticle-nanowire junction, the coupling efficiency of light to SPPs depends on the polarization of the excitation light. Theoretical simulations revealed that it is the local near-field coupling between the nanoparticle and the nanowire that enhances the incident light to excite the nanowire SPPs. Because the shapes of the Ag nanoparticles differ, the local field intensity, and thus the excitement of the nanowire SPPs, vary with the polarization of the excitation light.Physics, MultidisciplinarySCI(E)EI中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)[email protected]
Effects of shell thickness on the thermal stability of Cu-Ag core-shell nanoparticles: A molecular dynamics study
No full textCu-Ag core-shell (CS) nanoparticle (NP) is considered as a cost-effective alternative material to nano silver sintering material in die attachment application. To further reduce the cost, the thickness of the Ag shell can be adjusted. Whereas the shell thickness will also affect the thermal stability of the Cu-Ag CSNPs. In this study, molecular dynamics simulation was applied to study the thickness effect on the thermal behavior of Cu-Ag CSNPs. The melting points of CSNPs and Pure NPs can be determined by the evolutions of Potential Energy (PE), and the Lindemann index (LI) of the system. The results indicated that the melting points of CS NPs were lower than monometallic NP and the melting point of CS NP is influenced by the size of the Cu core and the number of lattice mismatches. Moreover, the distribution of atoms’ LI showed that the premelting point is independent of shell thickness. However, the fraction of atoms that occurred premelting is increased with the decrease of the shell thickness. Otherwise, we also simulated the sintering process of double CS NPs with equal size.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
Determining the spatial variation of accelerated electron spectra in solar flares
No full textThe RHESSI spacecraft images hard X-ray emission from solar flares with an angular resolution down to 2" and an energy resolution of 1 keV. In principle, images in different count energy bands may be combined to derive the hard X-ray spectrum for different features in the flare and hence to determine the variation of the (line-of-sight-integrated) electron spectrum with position in the image. However, images in different count energy bands are each subject to an independent level of statistical noise. Because of the inherent ill-posedness of the count electron spectral inversion problem, this noise is considerably amplified upon spectral inversion to obtain the parent electron spectrum for the feature, to the point where unphysical features can emerge. Imaging information is gathered by RHESSI’s Rotating Modulation Collimator (RMC) imagingsystem. For such an instrument, spatial information is gathered not as a set of spatial images, but rather as a set of (energy-dependent) spatial Fourier components (termed visibilities). We report here on a novel technique which uses these spatial Fourier components in count space to derive, via a regularized spectral inversion process, the corresponding spatial Fourier components for the electron distribution, in such a way that the resulting electron visibilities, and so the images that are constructed from them, vary smoothly with electron energy E. "Stacking" such images then results in smooth, physically plausible, electron spectra for prominent features in the flare. Application of visibility-based analysis techniques has also permitted an assessment of the density and volume of the electron acceleration region, and so the number of particles it contains. This, plus information on the rate of particle acceleration to hard-X-ray-producing energies [obtained directly from the hard X-ray spectrum ] allows us to deduce the specific acceleration rate (particles per particle). The values of this key quantity are compared with the predictions of variouselectron acceleration scenarios
Voltammetric Detection of Urea on an Ag-Modified Zeolite- Expanded Graphite-Epoxy Composite Electrode
No full textIn this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification.ChemE/Chemical EngineeringApplied Science
Ore mineralogy and trace element (re)distribution at the metamorphosed Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg, Sweden
No full textQualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfide minerals in the 1.89 Ga Lappberget deposit, with a focus on sphalerite and pyrite. Three sphalerite types were identified and associated with: (1) main massive sulfide mineralization, (2) Fe-Mn skarn ore, and (3) Ag-rich fissure veins. Sphalerite-1 contained a relatively higher amount of trace elements (Fe, Co, Ge, Cu, Sn, and Au) but is lower in Mn/Fe, Ga, and Hg compared to sphalerite-2. Evidence of tectono-metamorphic modification of sulfides is observed throughout the deposit, such as the formation of growth twins and deformation twins in sulfides, the development of high-angled triple-point junctions in recrystallized pyrite and sphalerite, and the formation of â??ball oreâ?? or â??durchbewegungâ?? textures within mineralized shear zones. The recrystallization of pyrite and galena may have led to the re-distribution of fluid-mobile elements (As, Cu, Zn, Pb, Ag, and Au), some of which were deposited in discordant Ag-rich fissure veins peripheral to the main massive sulfide lenses. Trace element signatures of sulfides in Lappberget are compatible with the other metamorphosed and deformed, subseafloor volcanogenic carbonate replacement (SVALS)-type deposits in the Bergslagen mining district. © 2021 The Author(s)</p
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