纳米二氧化硅表面功能化及其表征

采用自由基聚合接枝法,用甲基丙烯酸缩水甘油酯(glycidyl methacrylate,GMA)表面处理纳米二氧化硅,在其表面引入反应性环氧基团,对影响接枝反应的各种因素,包括单体浓度、引发剂浓度、反应温度和反应时间等进行了研究.结果表明,通过控制单体浓度可有效调控纳米二氧化硅的接枝率.采用红外(FT-IR)、热重分析(TGA)、光电子能谱(XPS)、透射电镜(TEM)等对改性纳米二氧化硅进行了表征.     

Voltammetry with microscopic electrodes in new domains

Voltammetric electrodes of microscopic dimension, termed ultramicroelectrodes, can be used to make measurements that are difficult or impossible with conventional electrochemical techniques. Measurements of chemical concentration can be made with these electrodes on a microsecond time scale and with micrometer spatial resolution. In addition, measurements can be made in highly resistive solutions.     

Conductance-controlled point functionalization of single-walled carbon nanotubes

We used covalent attachments to single-walled carbon nanotubes (SWNTs) to fabricate single-molecule electronic devices. The technique does not rely on submicrometer lithography or precision mechanical manipulation, but instead uses circuit conductance to monitor and control covalent attachment to an electrically connected SWNT. Discrete changes in the circuit conductance revealed chemical processes happening in real time and allowed the SWNT sidewalls to be deterministically broken, reformed, and conjugated to target species. By controlling the chemistry through electronically controlled electrochemical potentials, we were able to achieve single chemical attachments. We routinely functionalized pristine, defect-free SWNTs at one, two, or more sites and demonstrated three-terminal devices in which a single attachment controls the electronic response.     

Low-power switching of phase-change materials with carbon nanotube electrodes

Phase-change materials (PCMs) are promising candidates for nonvolatile data storage and reconfigurable electronics, but high programming currents have presented a challenge to realize low-power operation. We controlled PCM bits with single-wall and small-diameter multi-wall carbon nanotubes. This configuration achieves programming currents of 0.5 microampere (set) and 5 microamperes (reset), two orders of magnitude lower than present state-of-the-art devices. Pulsed measurements enable memory switching with very low energy consumption. Analysis of over 100 devices finds that the programming voltage and energy are highly scalable and could be below 1 volt and single femtojoules per bit, respectively.     

Thermal, catalytic, regiospecific functionalization of alkanes

The formation of a single product from terminal functionalization of linear alkanes from a transition metal-catalyzed reaction is reported. The rhodium complex Cp*Rh(eta(4)-C(6)Me(6)) (Cp*, C(5)Me(5); Me, methyl) catalyzes the high-yield formation of linear alkylboranes from commercially available borane reagents under thermal conditions. These reactions now allow catalytic, regiospecific functionalization of alkanes under thermal conditions. The organoborane products are among the most versatile synthetic intermediates in chemistry and serve as convenient precursors to alcohols, amines, and other common classes of functionalized molecules.     

Electronic structure control of single-walled carbon nanotube functionalization

Diazonium reagents functionalize single-walled carbon nanotubes suspended in aqueous solution with high selectivity and enable manipulation according to electronic structure. For example, metallic species are shown to react to the near exclusion of semiconducting nanotubes under controlled conditions. Selectivity is dictated by the availability of electrons near the Fermi level to stabilize a charge-transfer transition state preceding bond formation. The chemistry can be reversed by using a thermal treatment that restores the pristine electronic structure of the nanotube.     

诊断试剂用己糖激酶的制备工艺研究

为获得微生物工程菌株来源的己糖激酶(Hexokinase,HK)并提高HK的发酵水平,对已构建产HK的大肠工程菌株BW25113-pYBE/schk进行发酵工艺优化,为HK法血糖检测试剂盒的配制提供技术支撑。本研究采用正交试验对菌株发酵工艺进行优化,并对超声破壁获取粗酶及粗酶的纯化工艺进行研究。结果表明:工程菌株BW25113-pYBE/schk的最佳发酵培养条件为:装液量80mL/500mL,发酵液初始pH 6.5,发酵温度37℃,接种量2%,诱导剂添加时间为接种后1h,转速180r/min。超声破壁最佳工艺为:功率200 W,工作1.5s间歇1s,破壁5min。在最佳发酵和破壁工艺条件下,HK的发酵活力稳定在157U/mL,经过Ni-Agarose His标签蛋白试剂纯化获得60kD的HK。本研究建立了高产己糖激酶大肠杆菌工程菌株的发酵工艺,有利于降低己糖激酶法血糖试剂盒的成本,为糖尿病患者的准确诊断及普及提供便利条件。     

木质碳纤维材料的活化与功能化

为探讨用木质生物质替代石油等化石资源,制备新型功能化活性碳纤维材料,系统归纳了木质碳纤维在以下几方面的研究现状与发展趋势:1）以木质生物质为原料,通过固化、炭化,物理、化学活化处理,制备活性木材液化物碳纤维;2）通过孔隙调整、表面改性和离子化处理,对活性木材液化物碳纤维进行功能化处理;3）活性、功能化处理对木质碳纤维的晶体结构、表面含氧基团结构、孔隙结构和表面形态结构、物理性能和吸附性能、环保和抗菌功能的影响。并在此基础上,提出了今后一段时期内木质碳纤维的活化、功能化研究存在的科学问题与思考。      

多糖与蛋白质辅助官能化六方氮化硼纳米片载药及缓释性能

为减少传统农药使用过程中有机溶剂对环境的污染,提高农药的使用效率,用羧甲基纤维素(Carboxym-ethyl cellulose,CMC)和大豆分离蛋白(Soy protein isolate,SPI)辅助球磨机械剥离并改性六方氮化硼(Hexagonal boron nitride,h-BN)得到氮化硼基载体.采用浸...     

Surface spectroscopies with synchrotron radiation

A variety of photoelectron spectroscopies using synchrotron radiation have been devised to study solid surfaces. Measurements of the energies and angular distributions of electrons photoemitted from valence levels yield detailed information on surface electronic states and the chemical bonding of adsorbed atoms and molecules. Core level studies yield surface atom positions and molecular orientations. Some highlights of recent research are presented here. The capabilities of the techniques will be extended by the forthcoming generation of new storage rings dedicated to the production of synchrotron radiation.     

化学处理木材的动态粘弹性研究

为了弄清楚不同化学试剂处理引起木材内部分子构造的变化及其分子的运动状态,该研究针对杉木试材,采用动态粘弹性分析仪,测定了含水率在纤维饱和点状态下脱木素处理木材、DMSO处理木材和非晶化处理木材以及素材,在-100～10℃、0.5～10 Hz的动态粘弹性.研究结果表明:①在-100～10℃范围内观察到两个松弛过程,-30℃附近的α松弛过程和-100℃附近的β松弛过程;②频率越高,损耗模量峰值对应的温度越高,贮存模量随着温度的升高而降低;③α松弛过程中非晶化处理木材的活化能最高,DMSO处理木材次之,脱木素处理木材与素材接近;④木材发生α松弛过程的主要原因是吸着水分子的回转取向运动,发生β松弛过程的主要原因是无定形区细胞壁物质中的伯醇羟基基团的运动.      

不同药剂对甜瓜细菌性果斑病(BFB)带菌种子处理的影响

利用3种药剂及其不同浓度对甜瓜细菌性果斑病(BFB)带菌种子进行消毒处理,并调查药剂处理后种子发芽率、鲜重、根长、过氧化氢酶活性、丙二醛、发病率和嫁接后表现,结果表明,福尔马林100倍液和果腐净一号900倍液处理对甜瓜细菌性果斑病带菌种子消毒效果、生长等综合表现较优。     

固体氧化钴pH电极的研制

本文制备了一种可用于溶液pH值测定的固体氧化钴印刷电极。该电极可在2～12pH范围内呈现出良好的Nernst响应。文中就氧化钴的合成方法及印刷电极的制备工艺参数对电极响应行为的影响进行讨论。     

不同药剂处理对百合籽球膨大的影响

研究不同药剂处理对百合籽球膨大的影响,结果表明:K、Ca、KT、芸薹素内酯、膨大素对百合膨大均有一定效果,NAA对百合籽球的生长有毒害作用;以K浓度500mg/kg处理效果最好,种球鲜重提高42.12%,极显著高于对照。     

Chlorinated indium tin oxide electrodes with high work function for organic device compatibility

In organic light-emitting diodes (OLEDs), a stack of multiple organic layers facilitates charge flow from the low work function [~4.7 electron volts (eV)] of the transparent electrode (tin-doped indium oxide, ITO) to the deep energy levels (~6 eV) of the active light-emitting organic materials. We demonstrate a chlorinated ITO transparent electrode with a work function of >6.1 eV that provides a direct match to the energy levels of the active light-emitting materials in state-of-the art OLEDs. A highly simplified green OLED with a maximum external quantum efficiency (EQE) of 54% and power efficiency of 230 lumens per watt using outcoupling enhancement was demonstrated, as were EQE of 50% and power efficiency of 110 lumens per watt at 10,000 candelas per square meter.     

硫琼脂提取工艺的响应面法优化

采用EDTA-Na2法提取硫琼脂,采用硫酸钡比浊法及苯酚-硫酸法分别测定硫琼脂的硫酸根含量和总糖含量。在单因素试验的基础上,利用响应曲面法优化提取工艺,建立了EDTA-Na2加入量(A)、洗脱时间(B)和洗脱温度(C)与硫琼脂的主要理化指标(硫酸根+总糖)含量(Y)之间的数学模型,确定了硫琼脂提取的最佳工艺条件为:EDTA-Na2加入量为5.90g.L-1、洗脱时间2.2h、洗脱温度为53℃。按此最佳工艺提取的硫琼脂的主要理化指标(硫酸根+总糖)含量为(84.00±0.45)%。     

任意结构形状的电容传感器原理和数学模型

在木材工业中,木材含水率检测应用的单一平面电容传感器都是采用大量实验或近似数学模型实现检测的,难以控制和分析误差。鉴于此,并根据木材的介电常数与其含水率存在着一一对应的关系,该文研究了用于测量介电常数、具有任意几何结构形状的电容传感器。利用静电场及静电场中的导体和电介质的性质等相关理论,在电极和被测物处于任意几何结构形状和任意空间相对位置的状态下,建立了测量介电常数的电容传感器的精确数学模型。以经典物理学中已知结果的球形电容传感器为算例,得到了与传统电磁场理论中完全一样的结果,验证了所建立数学模型的正确性。      

水相凝胶色谱法测定草炭土溶解态有机质的分子质量及分子质量分布

以水为流动相,宽分布葡聚糖为标准,用水相凝胶色谱法测定土壤溶解态有机质的分子质量及分子质量分布.样品的进样量、流动相流速对测定结果无明显影响,测定结果的相对标准偏差小于10%.