A system for measuring elastic wave velocity under high pressure and high temperature using a combination of ultrasonic measurement and the multi‐anvil apparatus at SPring‐8

An experimental system to measure the elastic wave velocities of hot‐pressed polycrystalline samples at high pressure and high temperature has been installed at SPring‐8. It uses a combination of the ultrasonic pulse‐echo‐overlap method and Kawai‐type multi‐anvil apparatus (SPEED‐1500). X‐ray radiographic imaging enables the sample length to be determined at high pressure and high temperature, which is indispensable for precise determination of elastic wave velocity. Precise measurements of the elastic wave velocities of various minerals have been determined at pressures up to 19 GPa and temperatures up to 1673 K. The experimental technique provides the precise elastic wave velocities of various materials corresponding to those in the Earth's mantle.     

同步辐射X射线荧光微探针技术测定熔融包裹体中的微量元素

采用同步辐射X射线荧光微探针无损分析技术,对吉林龙岗火山群地幔捕掳体中的斜方辉石矿物及其熔融包裹体进行了测试,并用美国玻璃标样(NIST 612)标定出K,Sc,Ti,Cr,Mn,Fe,Co,Ni,Cu,Zn,Ga,Sr,Y等13种元素的含量.其中,斜方辉石中的Cr?,Mn?,Fe?,Ni等元素含量与波长色散电子探针分析结果相对误差分别为15%,5%,7%,8%.包裹体中过渡族元素球粒陨石标准化曲线型式与中子活化全岩分析结果相似,反映原始岩浆在上升过程中经历了部分熔融或分离作用     

The gas chromatographic determination of volatile fatty acids in wastewater samples: Evaluation of experimental biases in direct injection method against thermal desorption method

The production of short-chained volatile fatty acids (VFAs) by the anaerobic bacterial digestion of sewage (wastewater) affords an excellent opportunity to alternative greener viable bio-energy fuels (i.e., microbial fuel cell). VFAs in wastewater (sewage) samples are commonly quantified through direct injection (DI) into a gas chromatograph with a flame ionization detector (GC-FID). In this study, the reliability of VFA analysis by the DI-GC method has been examined against a thermal desorption (TD-GC) method. The results indicate that the VFA concentrations determined from an aliquot from each wastewater sample by the DI-GC method were generally underestimated, e.g., reductions of 7% (acetic acid) to 93.4% (hexanoic acid) relative to the TD-GC method. The observed differences between the two methods suggest the possibly important role of the matrix effect to give rise to the negative biases in DI-GC analysis. To further explore this possibility, an ancillary experiment was performed to examine bias patterns of three DI-GC approaches. For instance, the results of the standard addition (SA) method confirm the definite role of matrix effect when analyzing wastewater samples by DI-GC. More importantly, their biases tend to increase systematically with increasing molecular weight and decreasing VFA concentrations. As such, the use of DI-GC method, if applied for the analysis of samples with a complicated matrix, needs a thorough validation to improve the reliability in data acquisition.     

铝硅酸盐钙钛矿的晶格参数

 本文根据MgSiO₃－CaSiO₃－Al₂O₃系统在高温超高压下（p>40 GPa，T~1 500 ℃）合成铝硅酸盐钙钛矿的实验结果，并通过(Mg,Al)(Si,Al)O₃钙钛矿和(Mg,Fe)SiO₃钙钛矿的对比，研究组分对钙钛矿的晶格常数、畸变和稳定性的影响。查明在650 km的地震波速度不连续面以下的地幔中，Al₂O₃和CaO的存在形式。     

托卡马克等离子体的热平衡特性与脱栏现象

本文利用欧姆加热条件下简化的能量平衡方程研究了热传导与杂质辐射的综合效应。首先指出边缘辐射带的建立与随半径增大而增大的K=nx模型紧密相关(x为电子热传导系数,n为等离子体密度),然后利用删削层中能量平衡关系确定边界温度,自洽地求解了能量平衡方程,得出的脱栏等离子体形成条件能较好地解释有关实验观察到的多种现象。     

Effects of high pressure and temperature on carbon isotope compositions of some acyclic alkanes and preservation of organic matter

The effects of high pressure and temperature on carbon isotopic compositions of acyclic alkanes and the stability of the acyclic alkanes were experimentally investigated. The pyrolysis of lignite with water in a closed system was conducted at 400–700°C and 1–3 GPa. The carbon isotope data, variations of peak carbon and evident odd–even predominance of acyclic alkanes indicated that: (1) the high pressure retarded the maturation of organic matter and destruction of hydrocarbons, (2) n-C₁₂₊ hydrocarbons from biogenic sources could be preserved in the cool slab subducted into the upper mantle, and (3) some organic compounds might preserve the carbon isotope signals inherited from biogenic sources. The results favor tracing the origins of organic matter in mantle rocks and extraterrestrial organic matter in meteorites and the process of deep carbon cycle.     

Phase equilibria of multicomponent mineral systems at high pressures and high temperatures

Abstract

The substance of the Earth's upper mantle was essentially differentiated in the course of deep-seated magmatic processes. It is for the most part formed by peridotitic as well as pyroxenitic and eclogitic The most deep-seated ones pertain to the garnet-peridotitic facies. Liquidus phase relations between the minerals of primary garnet lherzolite (compositional estimations are given in Refs. 1–3) account for the regularities of the formation, evolution, crystallization of multicomponent silicate magmatic melts and petrogenesis of garnet-peridotitic mantle rocks.     

Historical perspective on the physics of artificial lighting

We describe the evolution of lighting technologies used throughout the ages, and how the need for improvements was such that any new technology giving better and cheaper lighting was immediately implemented. Thus, every revolution in energy sources – gas, petrol electricity – was first put to large-scale use in lighting. We describe in some detail several “ancient” techniques of scientific interest, along with their physical limitations. Electroluminescence – the phenomenon by which LEDs directly convert electricity into light – was long thought to only be of use for indicators or flat panel displays supposed to replace the bulky cathode-ray tubes. The more recent uses of LEDs were mainly for street traffic lights, car indicators, small phone displays, followed by backlighting of TV screens. LED lamps for general lighting only emerged recently as the dominant application of LEDs thanks to dramatic decrease in cost, and continuous improvements of color quality and energy conversion efficiency.     

The system Na2CO3–MgCO3 at 3 GPa

It was suggested that Na–Mg carbonates might play a substantial role in mantle metasomatic processes through lowering melting temperatures of mantle peridotites. Taking into account that natrite, Na₂CO₃, eitelite, Na₂Mg(CO₃)₂, and magnesite, MgCO₃, have been recently reported from xenoliths of shallow mantle (110–115?km) origin, we performed experiments on phase relations in the system Na₂CO₃–MgCO₃ at 3?GPa and 800–1250°C. We found that the subsolidus assemblages comprise the stability fields of Na-carbonate?+?eitelite and eitelite?+?magnesite with the transition boundary at 50?mol% Na₂CO₃. The Na-carbonate–eitelite eutectic was established at 900°C and 69?mol% Na₂CO₃. Eitelite melts incongruently to magnesite and a liquid containing about 55?mol% Na₂CO₃ at 925?±?25 °C. At 1050 °C, the liquid, coexisting with Na-carbonate, contains 86–88?mol% Na₂CO₃. Melting point of Na₂CO₃ was established at 1175?±?25 °C. The Na₂CO₃ content in the liquid coexisting with magnesite decreases to 31?mol% as temperature increases to 1250°C. According to our data, the Na- and Mg-rich carbonate melt, which is more alkaline than eitelite, can be stable at the P–T conditions of the shallow lithospheric mantle with thermal gradient of 45?mW/m² corresponding to temperature of 900 °C at 3?GPa.     

高压下顽火辉石的相态及其地球物理意义

 利用Birch-Murnaghan有限应变状态方程和Grüneisen状态方程,计算了钙钛矿型（Mg_0.86Fe_0.14SiO₃）和方镁石（Mg_0.86Fe_0.14O）与斯石英（SiO₂）混合物（摩尔比为1∶1）的Hugoniot压力-密度关系。将计算结果与实验数据比较后表明,在相同压力但不同温度的区域,上述两组相态都可能是顽火辉石的高温高压相态。但进一步通过与PREM的比较和分析后表明,在下地幔压力和温度条件下顽火辉石的相态应该是稳定的钙钛矿型,从而支持了Knittle等人的看法。