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

Characterization of Cu-ZnO-ZrO_2 Catalysts for Stream Reforming of Methanol by in situ Raman Spectroscopy

应用显微Raman光谱对Cu ZnO ZrO2 (Zr 2 4% ,w)催化剂催化甲醇水蒸气重整 (SRM)反应进行原位表征 ,并将结果与相同催化剂上的甲醇合成 (MS)反应进行对比 ,结果表明 :在SRM反应时 ,催化剂表面出现四个宽峰 ,其中 5 44 8和 65 2 8cm-1分别为CuO ZnO和ZrO2 的Raman吸收峰 ,而 13 61 8cm-1为HCOO—Cu对称伸缩振动吸收峰 ,在 15 90 3cm-1附近的谱峰归属于甲酸物种中OCO的不对称伸缩振动 .在由CO CO2 H2 合成气合成甲醇时 ,在 13 5 0cm-1和分别在 15 5 0 ,15 85 ,15 95cm-1出现两个甲酸根表面物种和甲酸盐的振动吸收谱带 .因此 ,在Cu ZnO ZrO2 催化剂上的甲醇合成和甲醇水蒸气重整存在相同的甲酸根中间体 ,这一结果将有助于对甲醇合成和甲醇水蒸气重整反应机理的理解 .Characterization of Cu-ZnO-ZrO 2 catalysts for stream reforming of methanol (SRM) by in situ Raman spectroscopy has been done. The results have been contrasted with those from reaction of methanol synthesis (MS) over the same catalysts. The results indicated that there are four Raman peaks on the surface of the catalyst for SRM reaction. The Raman spectra of 544 8 cm -1 were assigned to CuO-ZnO, 652 8 cm -1 to ZrO 2, 1361 8 cm -1 to symmetry flex oscillatory adsorption of HCOO—Cu and 1590 3 cm -1 to asymmetry flex oscillatory adsorption of OCO in formic acid species, respectively. The peak of 1350 cm -1 and three peaks of 1550, 1585 and 1595 cm -1 were assigned to Raman flex adsorbed band of formic acidic group and formic acidic salt on surface of catalyst for methanol synthesis. So formic acidic group existed on the surface of the catalysts for SRM and MS reactions. This result has an important significance for mechanism knowledge of SRM and MS reactions.福建省科学基金重大项目 (No .2 0 0 3H0 0 8);; 厦门市科技计划项目 (No .350 2Z2 0 0 2 1 0 87)资

急性甲醇中毒大鼠模型及其眼部改变的研究

【目的】探讨急性甲醇中毒大鼠模型的制作方法及其眼部改变，为研究中毒后视功能损害及救治方法建立基础。【方法】SD大鼠32只，随机分为A（低剂量甲醇组）、B（高剂量甲醇组）、C（生理盐水对照组）、D（空气对照组）4组，每组8只。A、B组吸入N2O／O2混合气及不同剂量甲醇灌胃，C组吸入N2O／O2混合气及生理盐水灌胃，D组置于正常空气中并按B组剂量给予甲醇灌胃，观察各组大鼠一般情况、体质量及眼部改变、静脉血甲醇浓度、视网膜电图和视网膜组织学改变。【结果】染毒大鼠反应迟钝、运动失调，视盘充血水肿、视网膜点状出血，A组大鼠体质量为（187±12）g，B组为（176±131g，较C、D对照组显著减轻（P〈0．05）；A组视网膜电图a、b波振幅分别为（87±13）μV、（187±38）μV，B组a、b波振幅分别为（53±19）μV、（132±39）μV，与对照组相比明显下降（P〈0．05）；视网膜在光镜下表现为各层细胞水肿、排列紊乱及空泡化；电镜下细胞凋亡，线粒体肿胀、嵴断裂；B组动物上述改变尤其明显。【结论】吸入N2O/O2混合气及甲醇灌胃可建立急性甲醇中毒的大鼠模型，出现典型的视网膜结构和功能改变

Study of the Interaction of Disubstituted Cucurbit[6]uril with 2-(Aminomethyl)pyridine

分别用核磁共振、紫外可见吸收和X射线单晶衍射方法研究对称四甲基六元瓜环与2-氨基甲基吡啶的相互作用及其结构特征.1HNMR谱图和紫外可见吸收光谱图清晰表明,2-氨基甲基吡啶与对称四甲基六元瓜环有明显的相互作用,客体2-氨基甲基吡啶的吡啶环部分进入了瓜环空腔,1HNMR谱图相关质子峰的积分强度以及客体吸光度随主体瓜环浓度变化明确表示它们之间形成了1∶1的包结配合物,此包结比并不随瓜环的浓度增加而改变.X射线单晶衍射法对包结配合物晶体的测定进一步证实了核磁共振、紫外可见吸收方法所得结论.Interaction and structure of a host-guest inclusion complex of symmetrical tetramethyl substi- tuted cucurbit[6]uril (TMeQ[6]) with 2-(aminomethyl)pyridine (amp) have been studied by using 1H NMR technique, UV-visible spectrophotometry and single crystal X-ray diffraction determination. The experimen- tal results from 1H NMR and UV-visible spectra revealed that the amp as a guest enters into the cavity of TMeQ[6] to form a host-guest inclusion complex of TMeQ[6] and amp with a constant ratio of 1∶1. The single crystal X-ray diffraction determination further confirmed the conclusions.国家自然科学基金(Nos.200261002,20362003);; 科技部国际科技合作重点计划(No.2003DF000030);; 贵州省省长资金;; 贵州省教育厅自然科学研究资助项目

Design and Fabrication of Al_2O_3/SiO_2 Double-Layer Antireflection Coatings on 4H-SiC Substrate

在4H-SiC基底上设计并制备了Al2O3/SiO2紫外双层减反射膜,通过扫描电镜(SEM)和实测反射率谱来验证理论设计的正确性。利用编程计算得到Al2O3和SiO2的最优物理膜厚分别为42.0nm和96.1nm以及参考波长λ=280nm处最小反射率为0.09%。由误差分析可知,实际镀膜时保持双层膜厚度之和与理论值一致有利于降低膜系反射率。实验中应当准确控制SiO2折射率并使Al2O3折射率接近1.715。用电子束蒸发法在4H-SiC基底上淀积Al2O3/SiO2双层膜,厚度分别为42nm和96nm。SEM截面图表明淀积的薄膜和基底间具有较强的附着力。实测反射率极小值为0.33%,对应λ=276nm,与理论结果吻合较好。与传统SiO2单层膜相比,Al2O3/SiO2双层膜具有反射率小,波长选择性好等优点,从而论证了其在4H-SiC基紫外光电器件减反射膜上具有较好的应用前景。Al2O3/SiO2 double-layer UV antireflection coatings were designed and fabricated on 4H-SiC substrate,and the validity of theoretical design was further verified by scanning electron microscope (SEM) and reflection spectrum. The optimal physical thickness of Al2O3 and SiO2 is 42.0 nm and 96.1 nm respectively by programming calculation. And then the minimum reflectance of 0.09% is obtained at reference wavelength λ=280 nm. According to error analysis,keeping the sum of double-layer thickness consistent with theoretical value is helpful to reduce the reflectance. In addition,the refractive index of SiO2 should more accurate and the refractive index of Al2O3 should be controlled close to 1.715 in the experiment. Al2O3/SiO2 double-layer coatings were deposited on 4H-SiC substrate by electron beam evaporation and the physical thickness is 42 nm and 96 nm respectively. SEM images show that the deposited layers and the substrate perform good adhesion to each other. The practical minimum reflectance is 0.33% at λ=276 nm which is close to theoretical value. Compared with conventional SiO2 single layer,Al2O3/SiO2 double-layer coatings show low reflectance and better wavelength selectivity. These results make the possibility for 4H-SiC based UV optoelectronic devices with Al2O3/SiO2 films as antireflection coatings

基于矩张量分析的特大山体破坏前兆孕震机制研究

工程岩体震源机制研究是岩体破坏灾害监测预警研究和应用的基础。针对一次特大爆破诱发的采空区上覆岩体产生特大破坏案例的前兆微震定位数据,采用矩张量理论对前兆微震源定位事件进行震源机制解反演,计算监测所得微震定位事件的矩张量并进行分解,获得纯双力偶成分MDC分量;采用Feigner和Young矩张量破裂判据计算得到破坏类型判别参数R值,对前兆微震事件的岩体破裂类型进行判断,同时根据矩张量分量计算震源体积不变部分参数T和体积变化部分参数k,据此绘制并研究了哈德森震源类型-T k图,分析表明前兆微震源的破裂类型主要为剪切破坏;进一步根据矩张量分解所得纯双力偶成分MDC分量,解得岩体震源处的断层参数。将震源机制解分析得到的前兆微震事件剪切破裂类型与现场山体宏观剪滑破坏相对比,其结果是基本一致的。研究表明基于微震矩张量理论对前兆震源机制解的分析,可较为准确地判断中尺度工程岩体破裂类型,该研究可作为进一步的中尺度工程岩体破裂机制研究以及岩体工程灾害预警研究参考。国家自然科学基金资助项目(51674218);;\n国家重点研发计划项目(2016YFC0600702

嗜虫耶尔森氏菌HlyA及HasA外分泌表达系统的构建

【目的】构建一株具备外分泌蛋白功能的工程菌,解决杀虫毒素无法由胞内分泌至胞外,无法直接作用于虫体等问题,为松墨天牛防治提供新思路。【方法】本研究先测定从松墨天牛肠道及其生境中分离出的嗜虫耶尔森氏菌(CSLH88)的生长特性及抗性,进而对其进行分子改造。构建HlyA (pGHKW2)以及HasA (pGHKW4)外分泌表达载体,利用电穿孔法将其转入CSLH88菌株,获得能够表达绿色荧光蛋白的工程菌。利用稀释涂板及荧光体式镜检测技术对两个质粒进行遗传稳定性检测,并采用SDS-PAGE及Western blotting技术验证蛋白外分泌功能。【结果】CSLH88菌株培养2–4 h能够进入对数生长期,并对卡那霉素(Kan)敏感。成功构建了含有Kan抗性基因的pGHKW2(GenBank:MK562405)和pGHKW4(GenBank:MK562404)两个外分泌表达载体的CSLH88工程菌株。其中,发现pGHKW4质粒更加适合在嗜虫耶尔森氏菌中稳定遗传。SDS-PAGE及Western blotting检测结果表明HlyA系统无法在CSLH88菌株中将目的蛋白分泌到胞外,而HasA系统则可以有效地发挥外分泌表达功能。【结论】通过对HlyA及HasA两个外分泌表达系统进行研究,从中筛选出HasA型血红素转运系统作为CSLH88菌株的外分泌表达系统,为后续外分泌杀虫毒素蛋白菌株构建以及CSLH88菌株的致病性研究奠定基础。国家重点研发计划课题(2017YFD0600105);;\n国家自然科学基金(31601905);;\n福建省科技厅自然科学基金(2016J01097);;\n福建省科技计划项目(2018N5002);;\n福建农林大学科研基金(xjq201614);福建农林大学林学院林学高峰学科项目(71201800720,71201800753,71201800779);;\n福建省大学生创新创业训练计划项目(201810389102);;\n福建省林业科学研究项目[Minlinke(2017)03]~

Study of the interaction of disubstituted cucurbit[6]uril with 2-(aminomethyl)pyridine

Interaction and structure of a host-guest inclusion complex of symmetrical tetramethyl substituted cucurbit[6]uril (TMeQ[6]) with 2-(aminomethyl)pyridine (amp) have been studied by using H-1 NMR technique, UV-visible spectrophotometry and single crystal X-ray diffraction determination. The experimental results from H-1 NMR and UV-visible spectra revealed that the amp as a guest enters into the cavity of TMeQ[6] to form a host-guest inclusion complex of TMeQ[6] and amp with a constant ratio of 1:1. The single crystal X-ray diffraction determination further confirmed the conclusions

对称四取代六元瓜环的合成及其2,2-联吡啶主客体化合物

利用二甲基取代甘脲的二醚与甘脲二聚体成功合成了新型取代六元瓜环——对称四甲基六元瓜环. 该瓜环的结构已被晶体结构鉴定、核磁共振谱以及质谱方法所证实, 分子中所含两个二甲基取代甘脲处于对位. 1H NMR表明该瓜环容易与吡啶衍生物形成主客体配合物

Synthesis and crystal structure of a novel self-assembled (1,4-discyclohexyl cucurbituril) sodium(I) complex

A novel complex of a new 1,4-dicyclohexyl cucurbituril(DCYQ[6]) with sodium(I) ion was synthesized, and the crystal structure was determined by X-ray diffraction technique. In this self-assembled entity both the cavity interaction of DCYQ[6] included a nitrate anion and the portal interaction of the dipole carbonyls of DCYQ [6] with sodium cations lead to form self assembled molecular capsules. The crystal structure of the entity shows a packing of the self assembled molecular capsules connected by hydrogen bonds of water molecules