热灯丝CVD金刚石膜硼掺杂效应研究

利用Ｒａｍａｎ谱和Ｘ射线衍射微分析研究了金刚石膜硼掺杂效应．研究发现，在硼浓度较低时，金刚石膜中非晶碳（Ｓｐ²键合）含量减少，而随着硼浓度增加，金刚石膜的Ｒａｍａｎ特征峰（Ｓｐ^３）向低频方向漂移，并且展宽和出现不对称．这是由于硼掺杂引起晶格变化及Ｆａｎｏ互作用所致 关键词：     

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采用二维轴对称双温度化学非平衡(2T-NCE)模型,模拟了带有水冷约束管的大气压直流电弧氩等离子体发生器.得出了不同工作参数下等离子体中电子温度、重粒子温度的变化关系,表明直流电弧等离子体有很强的非平衡特性,且变化规律十分明显.     

脂肪乳剂对术后胃肠外营养病人多不饱和脂肪酸代谢的影响

目前认为人体必需脂肪酸(EFA)是亚油酸(C18:2)和α-亚麻酸(C18:3),人体内最多的不饱和脂肪酸为油酸,无脂完全胃肠外营养(TPN)导致的EFA的缺乏临床上可观察到一系列症状,且已得到动物实验结果的证实,因此含有EFA成分的脂肪乳剂成了目前营养液中不可缺少的成分之一.人体摄入EFA后,一方面作为供能物质在体内燃烧,另一方面通过代谢产生一系列的延伸产物发挥其功能.但过量的供给脂肪酸会引起△-6去饱和酶的抑制,导致更不饱和脂肪酸的缺乏.脂肪酸是外科手术后的主要燃料,多不饱和脂肪酸代谢紊乱后,体内各种脂肪酸的比例失调,导致生物膜如红细胞膜脂质结构的改变.本研究观察创伤前后及输入不同剂量的必需脂肪酸(EFA)对红细胞膜磷脂脂肪酸组成和血清游离脂肪酸谱的影响.     

Developing cold-resistant high-adhesive electronic substrate for WIMPs detectors at CDEX

Herein we report a prototypical electronic substrate specifically designed to serve the weakly interacting massive particles(WIMPs)detectors at the China Dark Matter Experiment(CDEX).Because the bulky high-purity germanium(HPGe)detectors operate under liquid-nitrogen temperatures and ultralow radiation backgrounds,the desired electronic substrates must maintain high adhesivity across different layers in such cold environment and be free from any radioactive nuclides.To conquer these challenges,for the first time,we employed polytetrafluoroethylene((C2F4)n)foil as the base substrate,in conjunction with ion implantation and deposition techniques using an independently developed device at Beijing Normal University for surface modification prior to electroplating.The remarkable peeling strengths of 0.88±0.06 N/mm for as-prepared sample and 0.75±0.05 N/mm for that after 2.5-days of soaking inside the liquid nitrogen were observed,while the regular standards commonly require 0.4 N/mm^0.6 N/mm for electronic substrates.     

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研究了滑动弧放电过程中电参数的变化,并对滑动弧等离子体中的非平衡度和各个参数之间的关系进行了讨论。应用双通道电弧模型,对电弧在气流作用下运动规律进行了数值模拟,模拟所得的结果有助于分析滑动弧非平衡等离子体的产生机理。     

Transport characteristics of Rabi oscillations in the two-band superlattices

We investigated the transport characteristics of Rabi oscillations, by using numerical methods, within a two-band tight-binding model driven by dc－ac electric fields. We found that Rabi oscillations make the long-time average current a sharply change, i.e. the current have resonant peaks appearing. Rabi oscillations are destroyed by dephasing; these peaks are the signatures of Rabi oscillations on the current response. The strong interband coupling will change the conditions of Rabi oscillations and, correspondingly, changes the places where the current resonant peaks appear.     

Raman scattering from highly-stressed anvil diamond

The high-frequency edge of the first-order Raman mode of diamond reflects the stress state at the culet of anvil, and is often used for the pressure calibration in diamond anvil cell(DAC) experiments. Here we point out that the high-frequency edge of the diamond Raman phonon corresponds to the Brillouin zone(BZ) center Γ point as a function of pressure. The diamond Raman pressure gauge relies on the stability of crystal lattice of diamond under high stress. Upon the diamond anvil occurs failure under the uniaxial stress(197 GPa), the loss of intensity of the first-order Raman phonon and a stressdependent broad Raman band centered at 600 cm^-1 are observed, which is associated with a strain-induced local mode corresponding to the BZ edge phonon of the L1 transverse acoustic phonon branch.     

船载系泊状态下基于原子重力仪的绝对重力测量

重力场是反映地球质量分布及变化的重要参数,动态重力测量在地质调查、地球物理、资源勘探等领域有着重要应用.目前动态重力测量均基于相对测量原理,动态相对重力仪存在零点漂移问题,影响其测量性能.动态绝对重力仪可以为相对重力仪提供同步同址校准,解决其长漂问题,因此备受关注.本文基于原子重力仪和惯性稳定平台,搭建了一套船载绝对重力动态测量系统,并在船载系泊状态下开展了绝对重力动态测量实验.经评估,船载系泊环境下的重力测量灵敏度为16.6 mGal/Hz^-1/2,1000 s积分时间内重力测量的分辨率可达0.7 mGal.通过两周的绝对重力测量,评估了系统的稳定性.为了评估绝对重力的动态测量精度,将船上测量点与码头高精度绝对重力基准点的绝对重力值进行了比较,两点之间的绝对重力值差及其不确定度评估结果为(–0.072±0.134)mGal.本文结果为海洋相对重力仪的同时同船校准提供了一种新方案.     

Evidence for a High-Pressure Isostructural Transition in Nitrogen

We observed an isostructural phase transition in the solid nitrogen λ-N₂ at approximately 50 GPa accompanied by anomalies in lattice parameters, atomic volume and Raman vibron modes. The anomalies are ascribed to a slight reorientation of the nitrogen molecules, which does not seem to affect the monoclinic symmetry(space group p2_1/c). Our ab initio calculations further confirm the phenomena, and suggest an optimized structure for the λ-N₂ phase. In addition, a ne...     

基于扩展卡尔曼滤波算法的船载绝对重力测量数据处理

基于冷原子干涉仪的高精度绝对重力动态测量为海洋重力测量提供新的手段,因而备受关注.利用自己搭建的船载冷原子干涉式绝对重力测量系统,在中国南海某海域开展了一系列测量实验.在动态条件下,测量噪声的抑制对测量性能的提升至关重要.本文根据船载绝对重力动态测量系统的物理模型,提出了一种基于扩展卡尔曼滤波算法的动态绝对重力数据处理方法,对观测的原子干涉条纹数据进行了时域滤波处理,获得了绝对重力值的最优估计.基于该处理方法将航速小于2.1 km/h条件下的绝对重力测量灵敏度从300.2 mGal/Hz^1/2提升至136.8 mGal/Hz^1/2(T=4 ms).此外,将处理后的数据与利用地球重力模型(XGM2019)计算的数据进行了比对,发现两者符合度较好.这些结果证实了本文提出的数据处理方法的有效性,并为船载冷原子干涉式绝对重力测量系统的测量噪声的抑制提供了一种新的处理方法.