P- V- T Data of hexagonal boron nitride h BN and determination of pressure and temperature using thermoelastic equations of state of multiple phases

Abstract

A synchrotron x-ray diffraction study on hexagonal boron-nitride (hBN) was conducted at simultaneous high pressures and temperatures. The pressure applied to the sample is pseudo-hydrostatic up to 9.0 GPa and the temperature was homogeneous in the range of 300 K to 1280 K. A modified Rietveld profile refinement has been applied to these diffraction spectra of low symmetry and multiple phases observed in the energy-dispersive mode. Thermoelastic parameters of hBN were derived by fitting a modified high temperature Birch-Murnaghan equation of state. The results are: bulk modulus K=17.6 GPa, pressure derivative K′=?K/?P=19.5, temperature derivative [kdot]=?K/?T=?0.69 × 10^?2 Gpa/K, volumetric thermal expansivity α=a+bT with values of a=4.38 × 10^?5K^?1 and b=1.75 × 10^?8K^?2, respectively. It is observed that the thermal expansion and compression along different crystal axes are significantly different. The crystal c-axis is much more expandable and compressible than the a-axis. This is attributed to the layered structure of the hBN. Because the thermoelastic equations of state of hBN and NaCl are quite different, the unit cell volumes of these two materials, derived from the same diffraction pattern, can be used to derive the experimental P-T conditions. The large intersection angle of isochoric lines of these phases in P-T space ensures a determination of P-T with satisfactory precision. The application and limitations of this method in obtaining experimental pressure and temperature using diffraction data and thermoelastic equations of state of multiple phases are discussed.     

Combination of medical and health care based on digital smartphone-powered photochemical dongle for renal function management

Currently, the global healthcare market is increasing at high speed with the impendent global aging issue. Healthcare Industry 4.0 has emerged as an efficient solution towards the aging issue since it was integrated with ubiquitous medical sensors, big health processing platform, high bandwidth, speed technologies, and medical services, etc. It is believed to fulfil the requirement of the tremendously growing health market. The acquisition of medical data acts as the dominant precondition to implement the Healthcare Industry 4.0. In the same way, the widely available smartphone could serve as the best biomedical information collect station. In this study, a smartphone-powered photochemical dongle is demonstrated to precisely estimate blood creatinine from the fingertip blood, which works as a highly compact reflectance spectral analyzer with an enzymatically dry chemical test strip. Comparing with conventional laboratory facility for the evaluation and treatment of chronic kidney disease (CKD), it implemented the platform of point care with agreed accuracy. In order to estimate the efficiency of treatment and recovery of the CKD, the proposed photochemical dongle would provide a flexible and rapid platform for point of care. Furthermore, the proposed measured technology is very promising method for remote CKD management.     

Application of the quadrature method to flexural vibration analysis of a geometrically nonlinear beam

The quadrature method (OM) has been used in structural analysis only in recent years. In this study, OM is applied to flexural vibration analysis of a geometrically nonlinear beam. The numerical results by OM agree with the results by the finite element method. It is believed that this is the first attempt to solve a nonlinear dynamic problem by the quadrature method.     

关于空间型中的正螺面

将正螺面引入到一般的空间型中,在Beltrami-Klein坐标系下统一加以表示,并一致地详尽考察其度量、法向、第二基本形式及主曲率,推出正螺面是极小曲面.     

Electrodeposition of magnesium–lithium–dysprosium ternary alloys with controlled components from dysprosium oxide assisted by magnesium chloride in molten chlorides

In the work, Gibbs energy showed that MgCl₂ can chloridize Dy₂O₃ and release Dy(III) ions in the LiCl–KCl–MgCl₂–Dy₂O₃ melts. Dy(III) ions were observed by cyclic voltammetry, square wave voltammetry in melts. X-ray diffraction (XRD) pattern of melts indicated that Dy₂O₃ was chlorinated by MgCl₂ and formed DyCl₃. XRD pattern of non-dissolved residue, which was left after the melts were washed with water to remove the soluble salt, showed that the new compounds (i.e., DyOCl, MgO, and Dy(OH)₃) were produced. The concentration of Dy(III) reached a maximum when the concentration of Mg(II) ions exceeded 8?×?10^?4 mol cm^?3 in melts by inductive coupled plasma atomic emission spectrometer analyses of melts. Galvanostatic electrolysis was conducted to extract Dy element from LiCl–KCl–MgCl₂–Dy₂O₃ melts by forming Mg–Li–Dy alloys. The components of Dy and Li in alloys were controlled within a small range by the concentration of MgCl₂ in melts, current density, and additions of Dy₂O₃. XRD patterns of alloys indicated that Mg₃Dy phase was formed. Scanning electron microscope images with energy-dispersive X-ray spectroscopy showed that Dy elements were mainly distributed in the grain boundary. Grain size was refined, due to a more content of Dy elements in alloys by optical microscopy images.     

Latitudinal distribution of nitrogen isotopic composition in suspended particulate organic matter in tropical/subtropical seas

Natural nitrogen isotopic composition (δ(15)N) of suspended particulate organic matter (POM) and nitrogen fixation rates via (15)N(2) assay were measured in surface waters along 120° E from 30° N to 30° S in the Asian marginal seas (the East/South China Seas and the Sulu/Celebes/Java Seas) and the northeastern Indian Ocean in November-December 2005 and March 2006. The POM δ(15)N values ranged from-1.8 to 12.2‰ with an average of 3.6‰ and showed a decreasing trend towards the equator in both hemispheres. In parallel, the measured N(2) fixation rates showed an increase from the subtropical to the tropical seas. This implies that a higher contribution of (15)N-depleted POM was derived from enhanced N(2) fixation. Water temperature and the stability of water column were partly responsible for the observed variations in nitrogen fixation. The large-scale spatial variations in suspended POM δ(15)N and N(2) fixation rates suggest that the suspended POM δ(15)N may be a potential indicator of nitrogen fixation in surface waters in tropical/subtropical seas.     

Selective extraction of gadolinium from Sm2O3 and Gd2O3 mixtures in a single step assisted by MgCl2 in LiCl–KCl melts

The chloration of MgCl₂ was studied in the LiCl–KCl–MgCl₂–Gd₂O₃–Sm₂O₃ melts. Gd(III) and Sm(III) ions were observed by cyclic voltammetry and square wave voltammetry assisted by MgCl₂ in melts. X-ray diffraction (XRD) patterns of melts indicated Gd₂O₃ and Sm₂O₃ were chlorinated by MgCl₂ and formed GdCl₃ and SmCl₃. XRD patterns of non-dissolved residues, which were left after the melts were washed with water to remove the soluble salt, showed that the new compounds (i.e., GdOCl, SmOCl, MgO, Gd(OH)₃, and Sm(OH)₃) were produced. Potentiostatic electrolysis experiments were performed to extract Gd from Gd₂O₃ and Sm₂O₃ mixtures assisted by MgCl₂. Separation between Gd₂O₃ and Sm₂O₃ was also achieved in a single step with the formation of Mg–Li–Gd alloys. XRD patterns of alloys indicated that Mg₃Gd phase was formed. Scanning electron microscope images with energy dispersive X-ray spectroscopy showed Gd elements were mainly distributed in the grain boundary.     

PEOS功率倍增装置的物理设计与等离子枪实验

对PEOS功率倍增装置进行了物理设计与模拟计算并进行了脉冲等离子体枪实验。给出装置参数的选择方法,包括电路参数与PEOS参数的选择。为得到要求的功率倍增和能量传输效率,分析指出注入等离子体密度n_p与速度v_d的乘积要大而n_p相对要小,v_d要大;而且为断路快、阴极半径r要适当小;模拟计算结果证实了这一分析。对装置关键部件脉冲等离子体枪进行设计、研制和实验,在距枪60cm处测得碳离子速度v_d～5×10~(?)cm/s,离子密度n_p～4×10(?)/cm。     

回流式水冷超薄多层镜的研究

从理论和实验上讨论了水冷铜镜变形的规律, 从而设计出多种多层镜, 其中回流式多层镜在0.13MPa通水压力下净吸收86.9W激光功率时, 总变形仅 0.10μm,约为同等条件下普通水冷铜镜变形量的1/40。     

百焦耳KrF激光用二极管的实验

描述了脉宽１００ｎｓ强流脉冲电子束单向泵浦百焦耳级ＫｒＦ准分子激光用大面积二极管的实验研究。采用１２ｃｍ×７５ｃｍ长方形碳毡阴极，３０μｍ厚铝膜或九根间距１３ｍｍ，直径１．３ｍｍ的金属丝组成的阳极。当阴阳极间距为２０～２２ｍｍ，Ｍａｒｘ发生器电压１．１～１．２ＭＶ时，二极管峰值电压为６２０～６７０ｋＶ，峰值电流１５０～１７０ｋＡ，电子束总能量大于８ＫＪ，使电子束泵浦ＫｒＦ激光器最大输出能量达１０６Ｊ。