Fabrication and electrical properties of axial and radial GaAs nanowire pn junction diode arrays

We report on the fabrications and characterizations of axial and radial Ga As nanowire pn junction diode arrays.The nanowires are grown on n-doped Ga As（111）B substrates using the Au-catalyzed vapor–liquid–solid mechanism by metal–organic chemical vapor deposition（MOCVD）. Diethyl–zinc and silane are used as p- and n-type dopant precursors,respectively. Both the axial and radial diodes exhibit diode-like J–V characteristics and have similar performances under forward bias. Under backward bias, the axial diode has a large leakage current, which is attributed to the bending of the pn junction interface induced by two doping mechanisms in Au-catalyzed nanowires. The low leakage current and high rectification ratio make the radial diode more promising in electrical and optoelectronic devices.     

Molecular dynamics simulations on the wet/dry self-latching and electric fields triggered wet/dry transitions between nanosheets: A non-volatile memory nanostructure

We design a nanostructure composing of two nanoscale graphene sheets parallelly immersed in water.Using molecular dynamics simulations,we demonstrate that the wet/dry state between the graphene sheets can be self-latched;moreover,the wet→dry/dry→wet transition takes place when applying an external electric field perpendicular/parallel to the graphene sheets(E;/E;).This structure works like a flash memory device(a non-volatile memory):the stored information(wet and dry states)of the system can be kept spontaneously,and can also be rewritten by external electric fields.On the one hand,when the distance between the two nanosheets is close to a certain distance,the free energy barriers for the transitions dry→wet and wet→dry can be quite large.As a result,the wet and dry states are self-latched.On the other hand,an E;and an E;will respectively increase and decrease the free energy of the water located in-between the two nanosheets.Consequently,the wet→dry and dry→wet transitions are observed.Our results may be useful for designing novel information memory devices.     

VA-90气态原子化装置AA-670原子吸收分光光度计联用测定出口螺旋藻中总汞

汞是一种有毒元素,在人体内积蓄到一定浓度时能导致中毒,国家标准GB2762—94规定食品中汞的允许量最大不超过0.05mg·kg~(-1).螺旋藻是一种植物性菌类保健食品,蛋白质含量达60%～70%.在测定食品中总汞的方法中,有在强酸性介质中,用二氯化锡作还原剂的测汞仪法,以及用双硫腙与汞离子形成络合物的比色法.由于测汞仪的稳定性不足,仪器成本高,操作不便,故测汞仪法未能广泛应用,而比色法灵敏度较低,操作繁琐,所使用试剂毒性大,在实际工作较少使用.本法使用样品自动回流消化仪,VA-90气态原子化装置及原子吸收分光光度计,建立了测定出口螺旋藻中总汞的方法,进行了样品消化方式、还原剂用量、载气流量等方面的研究.结果表明,本法具有灵敏度高,精密度好,准确和简便快速等优点.由于样品消化和原子化装置     

利用光学渡越辐射进行强流束诊断

当匀速运动的带电粒子通过介质交界面时，在库仑场重建的过程中，会产生渡越辐射，位于可见光波段的渡越辐射被称为光学渡越辐射（OTR）。它作为一种束流诊断工具，具有空间分辨率高、时间响应快、多参数同时测量、对束流影响小、装置简单等特点，能够测量束剖面、发散角、发射度、能量、束流的宏脉冲长度和微脉冲长度等多个参数，因此在国外加速器领域得到了比较广泛的应用。     

模板法制备CdSe纳米材料及其光电性能

采用电化学沉积法,在阳极氧化铝（AAO）模板中成功制备出CdSe纳米管和纳米线。利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射分析（XRD）和能量色散X射线光谱仪（EDS）对材料的形貌、结构和元素组成进行了表征。借助紫外-可见吸收光谱等对材料光催化活性进行了研究。结果表明：通过控制沉积电量可成功制备CdSe纳米管和纳米线;CdSe纳米材料为立方晶型与六方晶型的混合,经350℃退火处理后,CdSe纳米材料中由立方晶型向六方晶型转变,光照开路电位差值明显增强,在0 V（vs SCE）电位下的光照电流密度也有所提高,光电转换性能增强;CdSe纳米线的吸收边在710 nm左右,禁带宽度约为1.85 eV,CdSe纳米管相对于CdSe纳米线具有更高的光电转换性能和光催化活性,经7 h光照后,罗丹明B降解效率高达53.93%,另外,本文还讨论了CdSe纳米材料在AAO模板孔壁的生长机理。     

含偶氮苯或联苯侧基聚醚螯合树脂的合成及其络合性能研究

通过聚环氧氯丙烷分别与4—氨基偶氮苯、4—氨基—2′,3—二甲基偶氮苯、4—氨基—4′—氯—联苯和4—羟基偶氮苯反应,合成了四种以聚醚为主链的偶氮和芳胺型螯合树脂,并研究了它们对Au(Ⅲ)、Pd(Ⅱ)、Pt(Ⅳ)、Hg(Ⅱ)、Cu(Ⅱ)和Pb(Ⅱ)的吸附性能。     

L—赖氨酸酯聚酰胺Gd（Ⅲ）配合物的合成

Ｌ－赖氨酸长链烷基酯与二乙三胺五乙酸双酸酐共缩聚，制得大分子配体，它与ＧｄＣｌ３反应得到相应的配合物．这些配合物具有比现在用于临床诊断的造影剂Ｇｄ（ＤＴＰＡ）更高的弛豫速率．