Detection of incoherent broadband terahertz light using antenna-coupled high-electron-mobility field-effect transistors

The sensitivity of direct terahertz detectors based on self-mixing of terahertz electromagnetic wave in field-effect transistors is being improved with noise-equivalent power close to that of Schottky-barrier-diode detectors. Here we report such detectors based on AlGaN/GaN two-dimensional electron gas at 77~K are able to sense broadband and incoherent terahertz radiation. The measured photocurrent as a function of the gate voltage agrees well with the self-mixing model and the spectral response is mainly determined by the antenna. A Fourier-transform spectrometer equipped with detectors designed for 340, 650 and 900~GHz bands allows for terahertz spectroscopy in a frequency range from 0.1 to 2.0~THz. The 900~GHz detector at 77~K offers an optical sensitivity about $1~\mathrm{pW/\sqrt{Hz}}$ being comparable to a commercial silicon bolometer at 4.2~K. By further improving the sensitivity, room-temperature detectors would find applications in active/passive terahertz imaging and terahertz spectroscopy.Comment: 4.5 pages, 5 figure

Underway observation of surface temperature and salinity in north South China Sea in September 2006

通过2006年9月南海北部开放航次的走航观测,得到了该海区多个断面的表层温度、盐度分布曲线。QuikScat海面风场资料显示观测期间处于西南季风向东北季风的转换阶段,走航观测所得的温、盐资料显示出在这一季风转换的特殊阶段该海区表层的水文特征。珠江口冲淡水的扩散范围在季风转向前后有显著的变化,低盐的冲淡水在西南季风阶段向珠江口外海区的东南方延伸较远,而在东北季风阶段则受珠江径流量、南海北部表层环流等因素的影响收缩至珠江口附近。闽南近岸和台湾浅滩南部表层具有低温高盐特征,但CTD资料表明台湾浅滩区域存在上升流,结合风场资料,可证实观测期间此处的上升流由海流-地形因素所造成。Based on the underway observation data of Joint Survey of Northern South China Sea in September 2006,the distributions of surface temperature and salinity along several sections were obtained.The sea surface wind field data from QuikScat indicated that September was the conversion period from southwest wind to northeast wind in 2006,and the temperature and salinity data obtained from the underway observation could give a clear demonstration of the hydrological character of the northern South China Sea during this special period.The extension of diluted water near the estuary of Zhujiang River had a major change after the monsoon conversion.During the phase of southwest monsoon,the diluted water could extend to the southeast to a larger distance;while the diluted water was confined to the nearby area of the estuary in the northeast monsoon.In the inshore area off south Fujian and southern part of Taiwan Bank there existed cold and high salinity waters.It was proved by the CTD data that an upwelling was active in the southern part of Taiwan Bank.Considering the northeast monsoon,it could be confirmed that this upwelling was driven by the current-topography effect.国家自然科学基金项目(40576015,40521003,40576013

Clinical effect of damage-control orthopedics in the treatment of severe pelvic fracture

目的探讨骨科损伤控制(dCO)治疗严重骨盆骨折的临床效果。方法回顾性分析本院2010年1月~2014年1月收治的201例严重骨盆骨折患者临床资料,其中采用dCO治疗的患者为试验组(n=104),未采用dCO治疗的患者为对照组(n=97),观察两组的院内死亡率、手术时间、术中失血量、术中输液总量、术后并发症发生率和6 H乳酸清除率。结果试验组、对照组分别有7例(6.7%)和22例(22.7%)死亡,死亡原因均为失血性休克和多器官功能不全综合征,两组院内死亡率比较差异有统计学意义(P=0.003)。试验组的手术时间显著短于对照组[(55.7±11.2)MIn VS(121.5±21.3)MIn,P=0.012);试验组的术中出血量、术中输液总量均显著少于对照组[(250.3±54.3)Ml VS(612.5±56.7)Ml,(4613.9±1135.4)Ml VS(8821.3±2030.4)Ml,P=0.008、0.006)]。试验组、对照组术后并发症发生率分别为17.3%和24.7%,两组比较,差异无统计学意义(P=0.262)。试验组的急性呼吸窘迫综合征发生率显著低于对照组(P=0.038)。试验组、对照组术后6 H乳酸清除率分别为21.3%和11.2%,两组比较,差异有统计学意义(P=0.004)。结论 dCO有助于提高严重骨盆骨折患者的生存率、降低急性呼吸窘迫综合征发生率。Objective To explore the clinical effect of damage-control orthopedics(DCO) in the treatment of severe pelvic fracture.Methods Clinical data from 201 patients with severe pelvic fracture from January 2010 to January 2014 were retrospectively analyzed.Patients applied DCO was classified into experimental group(n=104),and those who didn′t were categorized into control group(n=97).The hospital mortality,operative time,intraoperative amount of bleeding,intraoperative amount of transfusion,incidence rate of postoperative complication,and lactate clearance rate of 6-hour in two groups was observed respectively.Results There were 7(6.7%) and 22(22.7%) dead cases in experimental group and control group And the causes of death were hemorrhagic shock and multiple organ dysfunction syndrome.The hospital mortality between two groups displayed a statistical difference(P =0.003).The operative time in experimental group[(55.7±11.2) min] was obviously shorter than that in control group [(121.5±21.3) min](P=0.012).In experimental group,the intraoperative amount of bleeding and amount of transfusion during surgery [(250.3 ±54.3) ml and(4613.9±1135.4)ml] in control group,and it was(612.5±56.7) ml and(8821.3±2030.4) ml respectively.After comparison,the two indexes in experimental group was obviously less than that in control group(P=0.00,0.006).The incidence rate of postoperative complication in experimental group and control group was 17.3% and 24.7% respectively,which didn′t display a statistical difference(P=0.262).The incidence rate of acute respiratory distress syndrome(ARDS) in experimental group was obviously lower than that in control group(P=0.038).The lactate clearance rate of 6-hour after surgery was 21.3% and11.2% in the experimental group and control group with a statistical difference(P=0.004).Conclusion DCO is beneficial to improve the survival rate of patients with severe pelvic fracture and reduce the incidence of ARDS

EFFECT OF STRUCTURAL RELAXATION ON THE DEFORMATION BEHAVIOR OF A Zr64.13Cu15.75Ni10.12Al10 BULK METALLIC GLASS UNDER NANOINDENTATION

Structural relaxation by isothermal annealing below the glass transition temperature is conducted on a Zr64.13Cu15.75Ni10.12Al10 bulk metallic glass. The effect of structural relaxation on thermal and mechanical properties was investigated by differential scanning calorimetry and instrumented nanoindentation. The recovery of the enthalpy in the DSC curves indicates that thermally unstable defects were annihilated through structural relaxation. During nanoindentation, the structural relaxation did not have a significant influence on the serrated plastic flow behavior. However, Structural relaxation shows an obvious effect in increasing both the hardness and elastic modulus, which is attributed to the annihilation of thermally unstable defects that resulted from the relaxation

甲基丙烯酸长链烷基酯的基团转移聚合研究

进行了甲基丙烯酸长链烷基酯（庚、辛、壬酯的混合物）的基团转移聚合．得到了具有较高分子量和转化率．分子量分布较窄的聚合产物．研究了聚合条件对产物的分子量及分布，转化率，聚合速率的影响．探讨了聚合反应动力学．认为聚合体系的非极性不利于催化剂的离解，单体较大的空间障碍使扩散困难．均是表观活化能升高和转化难以完全的原因．发现此类单体的基团转移聚合对温度的依赖性极大，本体聚合无自加速现象，容易得到较高的分子量

稀薄大气密度涨落对高空超高速飞行器气动性能的影响

地球周围的大气环境特性,随高度的上升,显著变化。对于本文关心的高度100km附近高超声速飞行器气动特性而言,稀薄大气密度涨落影响是一个重要的问题。按照大气层划分,高度100 km属于热层。热层的下界高度约86 km,上界高度与太阳活动有关,在太阳宁静期约为200 km,太阳活动期约500 km。热层下接中间层(高度50～86 km),上连电离层(高度80～1000 km),大气研究已知,中间层主要受重力波和湍流影响,电离层主要受太阳活动和地磁效应影响。高度100 km附近空域,处在热层下界,重力波、湍流、太阳活动和地磁效应等均有影响,理论上需要Navier-Stokes方程和Maxwell方程..

基因编辑的法律与伦理问题

跨域同仁聚焦公共话题,本辑围绕基因编辑的法律与伦理议题,各位学者基于不同的立场与视角做出不同的评议。为尊重言论,兹实录对话,仅做最低限度的技术处理

中国海洋生物研究70年

随着中国"海洋强国"战略的提出,加快建设海洋类学科的发展成为历史必然,海洋生物是海洋不可分割的一部分,海洋环境和生物相互依存,相互作用,海洋生物研究重要性日益凸显。为纪念中国科学家在海洋生物领域的突出贡献,本文回顾了建国以来中国海洋生物相关的重要研究进展,梳理了中国科学家在海洋生物领域的突出贡献,系统总结并讨论了未来研究方向,抛砖引玉,希望籍此助推中国海洋生物研究的新高潮。国家自然科学基金项目(41876134,41876171)中国大洋矿产资源研究开发协会专项项目(DY135-E2-5-03)教育部长江学者特聘教授项目(T2014253

Influence of dicarboxylic acids on self-assembly process: Syntheses and structural characterization of new Ag(I) complexes derived from mixed ligands

通讯作者地址: Huang, RB (通讯作者), Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 2. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] the principle of crystal engineering, three new silver metal–organic coordination polymers, [Ag2(L1)2(L2)]·2H2O (1), [Ag2(L1)2(L3)]·H2O (2), [Ag2(L1)2(L4)]·2H2O (3) (L1 = 2-aminopyrimidine, L2 = oxalate anion, L3 = glutarate anion and L4 = 1,4-naphthalenedicarboxylate anion) have been synthesized by solution phase reactions of silver nitrate with various dicarboxylic acids and cooperative heterocyclic 2-aminopyrimidine ligand under the ammoniacal conditions. All the complexes have been characterized by elemental analyses, IR spectra and X-ray diffraction. In complex 1, L1 ligands are coordinated to Ag(I) metal centers in rare tridentate fashions, forming one-dimensional (1-D) ladder-like structure, which is interlinked by L2 anions to generate 2-D pleated molecular sheet. Complex 2 displays an interesting two-dimensional (2-D) tongue-and-groove structure containing a new kind of “T-shaped” unit. Meanwhile, each of 2-D bilayers is interlocked by four adjacent identical motifs to form three-dimensional (3-D) 5-fold interpenetrating conformation with weak Ag···Ag interactions. In complex 3, L1 ligands are coordinated to the Ag(I) ions to form 1-D polymeric chain. And L4 anions, acting as bridging linkers through corresponding μ2-carboxylates, link a pair of Ag(I) atoms from adjacent chains to yield 3-D supramolecular network. The structures of complexes 1–3 which span from 2-D to 3-D networks suggest that dicarboxylate anions play important role in the formation of such coordination architectures.National Natural Science Foundation of China 20721001 973 Project, MSTC 2007CB81530