Effects of Sr2+ substitution on the crystal structure,Raman spectra,bond valence and microwave dielectric properties of Ba3-xSrx(VO4)2 solid solutions

The effects of Sr²⁺ substitution for Ba²⁺ on microwave dielectric properties and crystal structure of Ba_3-xSr_x(VO₄)₂ (0 ≤ x ≤ 3, BSVO) solid solution were investigated. Such Sr²⁺ substitution contributes to significant reduction in sintering temperature from 1400 °C to 1150 °C. Both permittivity (∑_r) and quality factor (Q × f) values decreased with increasing x value, which was determined to be related with the descending values of average polarizability and packing fraction, whereas the increase in τ_f value was explained by the decreased average VO bond length, A-site bond valence. BSVO ceramics possessed encouraging dielectric performances with ∑_r = 12.2–15.6 ± 0.1, Q × f = 44,340 - 62,000 ± 800 GHz, and τ_f = 24.5–64.5 ± 0.2 ppm/°C. Low-temperature sintering was manipulated by adding B₂O₃ as sintering additive for the representative Sr₃V₂O₈ (SVO) ceramic and only 1 wt.% B₂O₃ addition successfully contributed to a 21.7% decrease in sintering temperature to 900 °C, showing good chemical compatibility with silver electrodes, which render BSVO series and SVO ceramics potential candidates in multilayer electronic devices fabrication.     

河南省干热岩赋存地质环境及找矿方向

干热岩是战略性清洁能源,属于固体矿产范畴,其赋存条件受控于地质环境。在河南省干热岩资源调查项目基础上,结合国内外干热岩成藏特征和钻探成果综合研究分析认为:河南省干热岩热源主要以侵入岩体热传导和地幔热传导(深部隐伏断裂对流热传导)2种模式;其成藏环境必须具备巨大的稳定的高导热性岩体、巨厚的稳定的低导热性上覆盖层和深部热源3个基本条件。针对目前干热岩资源找矿理论和钻探存在的问题,提出了河南省干热岩初步找矿方向和建议,明确了加大钻探技术和工艺研发的重大意义。     

豫北辉卫淇地区侵入岩就位机制的探讨

通过对1：5万区域地质调查资料的综合研究，豫北辉卫淇地区侵入岩主要形成于王屋期和燕山期，划分为两个独立单元和一个序列。根据区内侵入岩体的物质来源、出露形态、分布位置，内部结构、与围岩的接触特征、产状变化等并结合区域构造运动分析，认为其就位机制主要为被动方式。可为河南省鹤壁-焦作-济源地区铜铅锌矿调查评价提供找矿思路。     

河南省二三产业发展的路径选择探析

河南省是一个传统农业大省,在经济发展中面临着保障国家粮食安全、增加农民收入、转移农村剩余劳动力的压力,并受到资源和环境的约束。这既有因发展不足造成的原因也有因发展不当造成的原因。笔者认为走循环经济和新型工业化之路是河南省二三产业发展的必然路径选择,并对此提出了相应的发展思路和对策建议。     

河南省煤炭工业旅游开发初步研究

煤炭工业旅游的开发,在国内蓬勃兴起,成为旅游行业的一个新亮点。文章概述了河南省进行煤炭工业旅游开发的重要意义和有利条件,对河南省煤炭工业旅游资源的开发提出了初步的开发原则和开发建议。     

河南南阳隐山含锶磷钙铝矾矿物学特征

在河南省南阳变质岩地区的蓝晶石矿床中发现了极为少见的矿物——含锶磷钙铝矾。其主要化学成分为(%):Al_2O_332.71、CaO7.47、SrO5.94、P_2O_516.78、SO_319.42。该矿物的 X 射线衍射特征和晶胞参数接近于磷钙铝矾,热分析和红外光谱曲线同目前资料仅有的磷锶铝矾相类似,故定名为含锶磷钙铝矾。     

河南洋淇沟超镁铁质岩体边部糜棱岩成因

在河南西峡县洋淇沟岩体边部识别出大量以超镁铁质—镁铁质为主的多种类型糜棱岩，它们是康棱岩化橄榄岩、橄榄岩质糜棱岩、斜长角闪质糜棱岩等。这类岩石是岩体沿板块碰撞带构造侵位时强应变条件下的产物。     

Heavy metals in aquatic plants,clams, and sediments from the Chesapeake Bay,U.S.A. implications for waterfowl

Dry weight concentrations of cadmium, lead, copper and zinc were measured in clams, submerged aquatic macrophytes and sediments from several locations in the Chesapeake Bay region. Clam species included Macoma balthica, Mya arenaria, and Rangia cuneata; plant taxa included Najas spp., Potamogeton spp., Ruppia maritima, Vallisneria americana, and Zostera marina. Cadmium and lead concentrations were generally greater in whole plants than in soft tissues of clams, while the reverse was true for zinc; no marked trend was observed in copper concentrations. These results suggest that the changes occurring in the food habits of some Chesapeake Bay waterfowl towards increased clam utilization as a result of declining submerged plant abundances is not increasing ingestion of the nonessential metals cadmium and lead. Highest lead, copper and zinc concentrations were observed in sediments from the Patapsco River, which is probably due to the proximity of Baltimore Harbor. Highest cadmium concentrations were observed in sediments in the Port Tobacco River, a tributary of the Potomac River. These observations were generally consistent with high concentrations of the respective metal(s) in biota from these locations. Concentrations of the four metals in sediments were highly correlated to organic matter content.     

同济现代建筑思想的渊源与早期发展

同济大学建筑系是一所具有现代建筑思想渊源的院系。该系在新中国建筑教育整体转向苏联复古主义和学院派体系之后，仍然坚持不懈地对现代建筑及其教育进行了探索，体现出独特的个性色彩。文章将同济建筑系的现代建筑思想及其教育发展放在时代背景中加以考察，追溯其特点的渊源，并探讨其在复杂的内外环境下的系列发展过程。