Baddeleyite-Type High-Pressure Phase of TiO2

A high-pressure phase of TiO(2), which had been observed by shock-wave experiments and remained unresolved, has been studied by in situ x-ray diffraction. The single phase was formed at 20 gigapascals and 770 degrees C with the use of sintered-diamond multianvils; it has the same structure as baddeleyite, the stable phase of ZrO(2) at ambient conditions. The coordination number of Ti increases from six to seven across the rutile to baddeleyite transition, and the volume is reduced by approximately 9 percent.     

A High-Pressure Test of Birch's Law

The compressional wave velocities of polycrystalline NaCl and KCl have been measured to over 17 gigapascals, with the use of Brillouin scattering and the diamond anvil cell. This pressure corresponds to 40% compression for NaCl and 60% compression for KCl (including the volume change across the B1-B2 transition). The data obey Birch's Law, which predicts that the velocity of each material is linear with density, except across the B1-B2 phase transition in KCl. This deviation from Birch's Law can be rationalized in terms of an interatomic potential model wherein the vibrational frequencies of the nearest neighbor bonds decrease when going to the eight-coordinated B2 structure from the six-coordinated B1 structure.     

A High-Pressure Polymorph of Troilite, FeS

A new polymorph of FeS was produced in a diamond-anvil cell and observed at high pressure both optically and by x-ray diffraction. Fourteen x-ray reflections of the high-pressure FeS were recorded; however, the crystal structure is unknown. This form of FeS is stable at 25 degrees C only at pressures above approximately 55 kilobars. The transition to the lower pressure polymorph, troilite, is rapid and reversible.     

硅酸盐对黄瓜白粉病菌的毒力测定及田间药效

[目的]了解硅酸盐对黄瓜白粉病的防治效果.[方法]以25％三唑酮可湿性粉剂和70％甲基硫菌灵可湿性粉剂为对照药剂,研究硅酸钾和硅酸钠对黄瓜白粉病的病菌毒力及田间药效.[结果]硅酸钾和硅酸钠均对黄瓜白粉病菌生长有抑制作用,EC50分别为3.525、3.865 g/L;硅酸钾在稀释400、300倍,喷施1次条件下防治效果较低,分别为32.0％、53.8％,通过增加施用次数(2次)防治效果大幅上升,分别为83.2％、87.3％;硅酸钠在稀释400、300倍,喷施1次条件下的防治效果分别为52.8％、71.6％,喷施2次后分别上升到78.2％、89.3％.田间试验过程中发现,喷施硅酸钠、硅酸钾200倍稀释液后黄瓜植株开始产生药害现象,而喷施300～400倍稀释液处理10 d内分别施药2次,对黄瓜植株生长安全.[结论]试验结果为生产中硅酸盐的推广应用提供了参考.     

High-Pressure Synthesis of Molybdates with the Wolframite Structure

A series of small cation molybdates, MgMoO(4), MnMoO(4), FeMoO(4), CoMoO(4), NiMoO(4), and ZnMoO(4) with the wolframite structure characteristic of the corresponding tungstates have been synthesized at high pressure and temperature. The high-pressure compounds revert to the ambient pressure modifications if heated in air at 600 degrees C.     

Entropy Estimates for Some Silicates at 298{degrees}K from Molar Volumes

Third law entropies for silicates of Be, Mg, Ca, Zn, Na, and K containing the same anion group, for example, SiO(4) or SiO(3) or AlSi(3)O(8), are found to be linearly related to their molar volumes. The relationship between the molar volume and the entropy of silicates of Fe and Mn, atoms with unfilled d electron subshells, is different from that of other silicates. The linear correlations yield a useful method of estimating the entropies of ortho-, meta-, and framework silicates (feldspars and feld-spathoids). The estimated entropies of pyrope and almandine at 298 degrees K are 47.47 and 68.13 gibbs per mole, respectively.     

Lead: X-ray Diffraction Study of a High-Pressure Polymorph

An x-ray diffraction study of lead under pressure has shown that face-centered cubic structure transforms to the hexagonal close-packed structure at room temperature and a pressure of 130+/- 10 kilobars. The volume change for the transformation is -0.18+/- 0.06 cubic centimeter per mole.     

柴油机高压油管压力传感器设计

对柴油机高压油管进行应力分析，并以高压油管本身作为敏感元件设计应变式油管压力传感器，并将传感器安装在Ｓ１９５柴油机上进行测试。结果表明，所设计的高压油管压力传感器具有较高的灵敏度、良好的信号重现性与工作稳定性。     

High-Pressure Polymorph of Thulium: An X-ray Diffraction Study

An x-ray diffractiotn study of thulium at room temperature and high pressure by means of a diamond-anvil press has shown that thulium transforms from a hexagonal close-packed structure to the samarium type, as other rareearth elements (gadolinium, terbium, dysprosium, and holmium) do. Unlike the other rare-earth elements, thulium (hexagonal close-packed) has an axial ratio (c/a) that is independent of pressure within experimental error and the transition is reversible. The transition occurs with increasing pressure in the range of 60 to 116 kilobars. The lattice paralieters of the samarium-type phase of thulium at about 116 kilobars are a = 3.327 +/- 0.005 angstroms and c = 23.48 +/- 0.04 angstroms, and the volume change at the transition is estimated to be - 0.5 percent of the volume of the hexagonal close-packed phase at the transition.     

Crystal Structure of the High-Pressure Phase of Solid CO2

X-ray diffraction study of solid CO(2) at room temperature has shown that the powder pattern of the high-pressure phase, which supersedes the low-pressure cubic Pa3 phase at about 10 gigapascals, is consistently interpreted in terms of an orthorhombic Cmca structure. The orthorhombic cell at 11.8 gigapascals has dimensions of 4.330 +/- 0.015, 4.657 +/- 0.005, 5.963 +/- 0.009 angstroms for its a, b, and c faces, respectively, and a volume of 120.3 +/- 0.5 cubic angstroms. Four molecules contained in the unit cell are located at the base-centered positions with their molecular axes inclined at about 52 degrees with respect to the crystallographic c axis. The volume change associated with the Pa3-Cmca transition is close to zero. The structural dimensions obtained for the high-pressure crystalline phase of CO(2) are of great importance for a theoretical understanding of the role of intermolecular interactions, including quadrupole-quadrupole interactions, in molecular condensation.     

高压油管压力控制的数学模型与优化

目的优化高压油管的压力控制,研究高压油管设计与优化等问题。方法对流体流动过程及高压油管两端压力差进行分析,设置不同的单向阀开启时长,结合流体连续性方程式建立数学模型。结果建立流体流动数学模型,解出高压油管稳定在一定压力的单向阀开启策略。结论给出了燃油密度随压力变化的函数关系,解决柴油机高压油管稳定在不同环境压力及单向阀开启时长的优化问题。     

High-Pressure Elasticity of Iron and Anisotropy of Earth's Inner Core

A first principles theoretical approach shows that, at the density of the inner core, both hexagonal [hexagonal close-packed (hcp)] and cubic [face-centered-cubic (fcc)] phases of iron are substantially elastically anisotropic. A forward model of the inner core based on the predicted elastic constants and the assumption that the inner core consists of a nearly perfectly aligned aggregate of hcp crystals shows good agreement with seismic travel time anomalies that have been attributed to inner core anisotropy. A cylindrically averaged aggregate of fcc crystals disagrees with the seismic observations.     

瞬变高压与中温协同杀菌的试验研究

温度协同高压处理的方法已成为高压杀菌研究的重要方向。本研究基于高压泵产生的高压连续射流。将瞬变高压与中温热处理相结合。考察两者协同作用对食品微生物活力的破坏或抑制效果。结果表明：采用瞬变高压结合中温的杀菌方式，可以有效杀灭食品中的微生物，50℃协同80MPa的瞬变高压。处理2min就使细菌总茵落数下降4个对数级；此外，所选的实验系统能在高压下连续运行。将为高压加工技术的实际应用创造有利条件。     

现代拖拉机高压共轨电控燃油喷射技术

首先指出了传统柴油发动机燃油喷射系统的不足,对比之下,介绍了目前世界先进的高压共轨电控燃油喷射技术,包括其基本含义及技术特点;简介了高压共轨电控燃油喷射系统的主要组成与基本工作原理;概述了高压共轨电控燃油喷射技术的发展过程。     

Irradiation Effects in Glasses: Suppression by Synthesis under High-Pressure Hydrogen

Glasses synthesized under high pressure of hydrogen showed resistance to certain effects of irradiation. Paramagnetic and light-absorption effects associated with irradiated glasses were diminished by a factor as large as 20 in some glasses. Irradiation increases the concentration of hydroxyl ions, as evidenced by increased absorption in the 2.7-micron (3700 cm(-1)) infrared region for hydrogen-silica glasses.     

X-ray Diffraction to 302 Gigapascals: High-Pressure Crystal Structure of Cesium Iodide

X-ray diffraction measurements have been carried out on cesium iodide (CsI) to 302 gigapascals with a platinum pressure standard. The results indicate that above 200 gigapascals CsI at 300 K has a hexagonal close-packed crystal structure with the ideal c/a ratio of 1.63 +/- 0.01. The crystal structure and pressure-volume relations converge at high pressure with those of solid xenon, which is isoelectronic with CsI. The results indicate a significant loss of ionic bonding in the hexagonal close-packed metallic phase of CsI at ultrahigh pressure.     

硅酸盐及腐植酸对Cr-Pb污染土壤中小白菜的生长和生理的影响

针对硅酸盐或腐植酸在重金属污染土壤上的最佳施用量研究较少的问题,为保障蔬菜的品质安全,本文通过土壤盆栽试验,研究了硅酸盐、腐植酸对Cr和Pb单一污染及Cr-Pb复合污染土壤中小白菜(Brassica Chinensis)的生物量、生理指标的影响.结果表明,施用硅酸盐对Cr-Pb污染的的抑制效果较好.其中1.0 g·kg-1质量分数的硅酸盐施用效果最佳,在小白菜未受污染时能促进生长;在受Cr-Pb污染后虽然促生长作用不明显,但施用后能有效减轻Cr-Pb污染对小白菜体内超氧化物歧化酶(SOD)活性的抑制,缓解小白菜根部细胞受到的过氧化损伤.同时发现,施硅量过高(2.0 g·kg-1)或当土壤中存在Pb污染时施用1.5 g·kg-1以上质量分数的硅酸盐则对生长产生抑制.腐植酸也能在一定程度上提高超氧化物歧化酶(SOD)、过氧化物酶(POD)的活性,但是对小白菜受到过氧化胁迫的缓解效果不如硅酸盐明显,对小白菜生长的促进作用不显著.