375 resultados para astro-ph.SR
Resumo:
This paper introduced a long-term ambulatory intragastric pH monitoring system, which is designed for prolonged ambulatory studies of Gastroesophageal Reflux Diseases. The whole system is composed of the gastric catheter with two pH sensors, a small data logger (Microdatalog), and a notebook PC. In this paper, the design of monitoring system hardware and software are described in detail. Clinical applications reveal good results.
Efficient synthesis of high-quality MCM-48 silicas through mixed surfactants and pH adjustment route
Resumo:
对贵阳地区22个雨水样品的化学组成和Sr同位素的研究表明,贵阳地区大部分雨水样品的pH值小于5.6(pH=4.53).雨水中Ca^2+是最主要的阳离子,平均值为57μmol·l^-1(12-164μmol·l^-1),占阳离子组成的64%-87%;Mg^2+是次要的阳离子,平均值为13μmol·l^-1(5—4μmol·l^-1),Ca^2+和Mg^2+之和占了阳离子组成的78%-96%;K^+平均值为11μmol·l^-1(2—44μmol·l^-1);Na^+最少,其平均值为4μmol·l^-1(1—8μmol·l^-1).SO4^2-是最主要的阴离子,平均值为941μmol·l^-1(34—279μmol·l^-1),占阴离子组成的28%-94%;NO3^-是次要的阴离子,平均值为48μmol·l^-1(1-252μmol·l^-1),SO4^2-和NO3^-是决定雨水酸度最主要的离子,SO4^2=和NO3^-之和占阴离子组成的77%-99%;Cl^-最少,平均值为20μmol·l^1(1—128μmol·l^-1).贵阳地区雨水中Sr的浓度为0.02-O.33μmol·l^-1,^87Sr/^86Sr比值较小(0.707934-0.709080),非海盐来源的^87Sr/^86Sr比值为0.707820-0.709078.元素比值及Sr同位素组成辨识出贵阳地区雨水溶质主要来源于人为活动,岩石/土壤化学风化次之,海相输入很小或可以忽略不计.
Resumo:
云南会泽铅锌矿田是我国著名的超大型特富铅锌矿田之一,由相距3公里的矿山厂和麒麟厂两个独立的矿床组成,Zn+Pb金属量超过五百万吨,矿石品位在25%至35%之间。为确定矿床成矿流体和成矿金属来源,本文系统研究了矿床的Ph、S、C、O、H和Sr同位素组成特征。矿石硫化物的铅N位素组成均一,^206Pb/^204Pb,^207Pb/^204Pb和。^206Pb/^204Pb的变化范围分别为18.251~18.530,15.663~15.855和38.487~39.433,与围岩碳酸盐岩中浸染状黄铁矿一致,与碳酸盐地层相近,在^208Pb/^204Pb-^206Pb/^204Pb图上显示明显的线性关系,表明铅N位素组成相近的碳酸盐围岩地层提供了成矿物质。矿石硫化物的δ^14S变化范围为10.9‰~17.4‰,多数集中于13‰~17‰,表明还原硫主要来自地层中海相硫酸盐的还原,还原方式为热化学还原,下伏页岩、碎屑岩和泥质岩中的有机质在硫酸盐还原过程中发挥了重要作用。三种不同产状的脉石矿物方解石的碳氧同位素组成均一且没有明显差别,δ^13C变化范围为-2.1‰~-3.5‰, δ^18O为16.8‰~18.6‰。脉石矿物方解石中流体包裹体水的δDFI为-50‰~-60‰,取温度为200℃计算包裹体水的δ^18OH2O值为7.0‰~8.8‰。碳、氧和氢、氧同位素研究结果表明,成矿流体为来自下部上升的变质流体,由于下伏页岩、碎屑岩和泥质岩中有机质的参与,成矿流体具有低的δ^13C和δ^13DFI值,在上升过程中与围岩发生了同位素交换。矿石中黄铁矿、闪锌矿和方解石的初始锶同位素组成(^87Sr/^86Sr).值的变化范围为0.714~0.717,赋矿围岩中未蚀变白云岩的初始锶同位素组成(^87Sr/^86Sr).值为0.7083~0.7093,明显低于蚀变白云岩(0.7106),表明成矿流体具有高的(^87Sr/^86Sr),比值。相对围岩碳酸盐岩而言,下伏地层中的页岩、碎屑岩和泥质岩往往具有高得多的^87Sr/^86Sr,因此,流经或者起源于这些地层的流体具有高的锶同位素比值.
Resumo:
Er3+ doped multicomponent fluoride based glass was prepared. These precursor fluoride glass samples were then heated using different schedules. Crystalline phase particles were successfully precipitated in the multicomponent fluoride glass samples after heat treatment. The influence of heat treatment on the spectroscopic properties of Er3+ in multicomponent fluoride based glass samples were discussed. Small changes of the Judd-Ofelt parameters Omega(i) (i = 2,4,6) were found in multicomponent fluoride glass samples before and after heat treatment compared to oxyfluoride telluride glass. Preparation conditions used to produce transparent multicomponent fluoride glass ceramics doped with rare-earth ions are discussed. (c) 2007 Elsevier B.V. All rights reserved.
Resumo:
应用中频感应提拉法生长了新型的Nd:(La,Sr)(Al,Ta)O3(Nd^3+:LSAT)晶体。运用电感耦合等离子体原子发射光谱仪(ICPAES)测定Nd^3+离子在Nd^3+:LSAT晶体中的分凝系数为0.587。X射线粉末衍射(XRPD)测试结果表明Nd^3+:LSAT晶体与LSAT晶体同构。研究了不同退火条件对晶体光谱性能的影响。分析了Nd^3+:LSAT晶体的光谱性能,Nd^3+:LSAT晶体的荧光寿命为290μs。比较了Nd^3+:LSAT和Nd^3+:YAG,Nd^3+:YVO3等晶体的光谱
Resumo:
Crystalline beta-BBO thin films were successfully prepared on (001)-oriented Sr2+-doped alpha-BBO substrates by using liquid phase epitaxy, pulsed laser deposition and vapor transport equilibration techniques. The films were characterized by X-ray diffraction and X-ray rocking curve. The present results manifest that the beta-BBO thin films grown on Sr2+-doped alpha-BBO substrates have larger degree of orientation f value and smaller X-ray rocking curve FWHM than the ones grown on other reported substrates. Compared with other substrates, alpha-BBO has the similar structure, the same UV cutoff and the same chemical properties to beta-BBO. These results reveal that Sr2+-doped alpha-BBO single crystal may be a promising substrate proper to the growth of beta-BBO films.
Resumo:
A new laser crystal Nd3+:(La, Sr)(Al, Ta)O-3 (abbreviated as Nd3+:LSAT) has been grown by the conventional Czochralski method. The absorption and luminescence spectra of trivalent neodymium in Nd3+:LSAT crystal were measured at room temperature. The value of absorption and emission cross-section was calculated. The Judd-Ofelt analysis was applied to the crystal to get the phenomenological parameters (Omega(i), i = 2,4,6), the line strengths, the radiative transition rates, the branching ratios and the radiative lifetime. (C) 2006 Elsevier B.V. All rights reserved.
Resumo:
采用气相传输平衡技术在掺Sr^2+的α-BBO(001)衬底上制备了β-BBO薄膜,研究了粉料配比、VTE处理温度以及恒温时间对薄膜质量的影响。结果表明,在适当的粉料配比、VTE处理温度以及恒温时间下,在Sr^2+:α-BBO晶片表层制备呈c轴高度择优取向的、没有第二相物质的β-BBO薄膜,其双晶摇摆曲线半峰宽值FWHM为1000",显示出β-BBO薄膜较好的结晶质量。并对气相传输平衡技术制备β-BBO薄膜的机理进行了初步的探讨。