510 research outputs found

    Specific volumes of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy in the liquid, glass, and crystalline states

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    The specific volumes of the Zr41.2Ti13.8CU12.5Ni10.0Be2.25 alloy as a function of temperature, T, are determined by employing an image digitizing technique and numerical calculation methods applied to the electrostatically levitated spherical alloy. The linear fitting of the volumes of the alloy in the liquid, V-l, glass, V-g, and crystalline V-c, states in the temperature ranges shown in parentheses are V-l(T) = 0.1583 + 8.877 x 10(-6)T(cm^(3)/g) (700-1300 K); V-g(T) = 0.1603 + 5.528 x 10^(-6)T (400-550 K); V-c(T) = 0.1583 + 6.211 x 10(-6)T(400-850 K). The average volume thermal expansion coefficients within the temperature ranges are determined to be 5.32, 3.39, and 3.83 x 10^(-5) (1/K) for the liquid, glass, and crystalline states, respectively

    Waste hemp hurd as a sustainable precursor for affordable and high-rate hard carbon-based anodes in sodium-ion batteries

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    The present study reports the promising potential of waste hemp-hurd-derived carbons as anodes in sodium-ion batteries (SIBs). Carbons were produced through an easily scalable process consisting of pyrolysis of raw biomass at 500 °C followed by mild chemical activation of the resulting char through wet impregnation with K2CO3 and subsequent heating of the solid phase (after filtration and drying) up to 700 or 800 °C under nitrogen. The best electrochemical performance was observed for the hard carbon activated at a char-K2CO3 mass ratio of 1:4 and heated up to 800 °C, which exhibited an excellent initial coulombic efficiency (73%) and achieved reversible charge capacities of 267 and 79 mAh g–1 at 0.03 and 1 A g–1, respectively. This material also exhibited an impressive cyclic stability and rate capability, with a capacity retention of 96% after 300 cycles at a current density of 2 A g–1. This more than satisfactory performance could be related to the textural and structural features of the hard carbon, which include moderate interconnected microporosity (with pore sizes below 1 nm), an appropriate concentration of defects in the carbon structure, relatively large interplanar distances, and a certain number of closed pores

    Single-Molecule-Sensitive FRET in Freely-Diffusing Attoliter Droplets

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    Fluorescence resonance energy transfer (FRET) from individual, dye-labeled RNA molecules confined in freely-diffusing attoliter-volume aqueous droplets is carefully compared to FRET from unconfined RNA in solution. The use of freely-diffusing droplets is a remarkably simple and high-throughput technique that facilitates a substantial increase in signal-to-noise for single-molecular-pair FRET measurements. We show that there can be dramatic differences between FRET in solution and in droplets, which we attribute primarily to an altered pH in the confining environment. We also demonstrate that a sufficient concentration of a non-ionic surfactant mitigates this effect and restores FRET to its neutral-pH solution value. At low surfactant levels, even accounting for pH, we observe differences between the distribution of FRET values in solution and in droplets which remain unexplained. Our results will facilitate the use of nanoemulsion droplets as attoliter volume reactors for use in biophysical and biochemical assays, and also in applications such as protein crystallization or nanoparticle synthesis, where careful attention to the pH of the confined phase is required.Comment: Twenty-three pages, 3 figures, one table, plus supporting information with additional figures and table

    A single hollow beam optical trap for cold atoms

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    We present an optical trap for atoms that we have developed for precision spectroscopy measurements. Cold atoms are captured in a dark region of space inside a blue-detuned hollow laser beam formed by an axicon. We analyze the light potential in a ray optics picture and experimentally demonstrate trapping of laser-cooled metastable xenon atoms.Comment: 12 pages, 8 figure

    Perbedaan Asupan Lemak, Lingkar Pinggang dan Persentase Lemak Tubuh pada Wanita Dislipidemia dan Non Dislipidemia

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    Differences of fat intake, waist circumference and percentage of bodt fat in dyslipidemia and non dyslipidemia adult women: Heart disease is the leading cause of death in several countries in the world . One of the major risk factors for heart disease is dyslipidemia . Dyslipidemia is a disorder of lipid metabolism characterized by an increase or decrease in plasma lipid fractions . Dyslipidemia has a strong relationship with the occurrence of central obesity . The purpose of this study was to analyze differences in the intake of fat , waist circumference and body fat percentage in dyslipidemia and non dyslipidemia adult women. This research is analytic study with cross sectional approach . The population in this study were adult women who examined their lipid profile in December 2013 in the Clinical Laboratory Cito Indraprasta Semarang . The total sample was 32 people . Independent test analysis of the differences using t-test for variables waist circumference and Mann Whitney test for variable fat intake and body fat percentage to 95 % and a significance level of 5% error. The results showed 17 adult women ( 53.1 % ) and 15 female adult dyslipidemia ( 46.9 % ) non- dyslipidemia. Average intake of fat, waist circumference and percentage body fat in adult women dyslipidemia higher than non dyslipidemia in adult women. Analysis of statistical tests showed difference in fat intake , waist circumference and body fat percentage in women adult dyslipidemia and non dyslipidemia (p value, respectively p = 0.002, p = 0.0001 and p = 0.0001

    Quadrupole and Hexadecapole Correlations in Rotating Nuclei Studied within the Single-j Shell Model

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    The influence of quadrupole and hexadecapole residual interactions on rotational bands is investigated in a single-j shell model. An exact shell-model diagonalization of quadrupole-plus-hexadecapole interaction can sometimes produce a staggering of energy levels in the yrast bands.Comment: 15 pages, 9 Postscript figures, REVTEX, to be published in PR
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