单分散掺硫碳微球的水热制备及其表征

以可溶性淀粉为碳源,采用硫辅助水热碳化法一步制备了平均粒径约为4 μm的单分散掺硫碳微球。利用扫描电镜、透射电镜、X射线衍射、氮气吸脱附、傅里叶变换红外光谱、X射线光电子能谱、固体核磁共振等手段对掺硫碳微球的结构和性质进行了表征。硫辅助水热碳化法可以在高浓度条件下高产量地制备分散性良好的掺硫碳微球,更重要的是硫原子可以同步进入碳的网络结构中。与传统水热碳化法相比,采用硫辅助水热碳化法制备的掺硫碳微球具有更高的比表面积,其可能的原因是硫原子的引入产生了大量的化学与结构缺陷:-S-S-、-S-、-SO₂-和-SO-等基团构成化学缺陷,而噻吩等五元环取代石墨六元环形成结构缺陷。     

单分散掺硫碳微球的水热制备及其表征

以可溶性淀粉为碳源,采用硫辅助水热碳化法一步制备了平均粒径约为4μm的单分散掺硫碳微球。利用扫描电镜、透射电镜、X射线衍射、氮气吸脱附、傅里叶变换红外光谱、X射线光电子能谱、固体核磁共振等手段对掺硫碳微球的结构和性质进行了表征。硫辅助水热碳化法可以在高浓度条件下高产量地制备分散性良好的掺硫碳微球,更重要的是硫原子可以同步进入碳的网络结构中。与传统水热碳化法相比,采用硫辅助水热碳化法制备的掺硫碳微球具有更高的比表面积,其可能的原因是硫原子的引入产生了大量的化学与结构缺陷:-S-S-、-S-、-SO2-和-SO-等基团构成化学缺陷,而噻吩等五元环取代石墨六元环形成结构缺陷。     

基于Cu_xO电子转移助剂及TiO_2价带边调控的协同效应驱动可见光催化(英文)

TiO_2基光催化剂迈向实际应用的关键在于更加有效地分离电荷和拓宽光吸收范围至可见光区域.通过担载助剂促进光生电荷分离以及掺杂调控能带、提高可见光吸收是实现高性能光催化剂的两个重要途径.在众多助剂中,廉价、无毒且催化性能优异的过渡金属氧化物(如Co-,Ni-,Cu-和Fe-氧化物)助剂在光催化降解污染物、水分解、CO_2还原等领域尤其引人关注.而氧缺陷作为氧化物的固有缺陷,可实现TiO_2的能带调控,提升可见光吸收性能.其中,常见的缺氧缺陷是通过导带边调控来拓宽可见光吸收范围,但其光生电子还原能力降低.因TiO_2价带空穴具有足够强的氧化能力,本文拟通过在TiO_2中引入富氧缺陷调控价带边及担载电子转移助催化剂的途径研制高效可见响应型光催化剂.本文利用超声喷雾热解过氧钛酸和湿化学浸渍法制备了Cu_xO负载富氧型TiO_2微球.采用扫描电子显微镜(SEM),透射电子显微镜(TEM),N_2吸附-脱附等温曲线,X射线衍射(XRD),X射线光电子能谱(XPS),紫外可见漫反射光谱(UV-Vis-DRS)等手段对Cu_xO负载富氧型TiO_2微球的结构特征和光谱吸收性质进行系统研究.SEM,TEM和N2吸附/脱附等温曲线结果表明,Cu_xO负载富氧型TiO_2微球是纳米颗粒紧凑堆叠的介孔微球,直径为200–2000 nm,Cu元素高度均匀分散于微球上.XRD和XPS分析表明,富氧缺陷TiO_2微球相比参照TiO_2微球具有更大的晶格参数,同时晶体中具有大量的过氧物种(Ti-O-O),证明了过氧缺陷的存在.UV-Vis-DRS和XPS的价带谱验证,富氧缺陷使得TiO_2价带顶上移,提高了可见光吸收性能.鲁米诺化学发光(CL)探针实验进一步证明,表面负载的Cu_xO助剂将表面吸附氧高效还原为活性氧物种(O2·–和H_2O_2),提高了光生电子利用率.因此,Cu_xO负载富氧型TiO_2微球表现出更快的可见光催化降解乙醛速率,分别为富氧型TiO_2、非富氧型TiO_2和Cu_xO-TiO_2的8.6、13.0和11.0倍.并且,Cu_xO负载富氧型TiO_2微球在可见光催化降解乙醛的五次循环实验中,活性基本保持不变.Cu_xO负载富氧型TiO_2微球在模拟太阳光和UV光辐照下光催化降解乙醛速率相比富氧型TiO_2微球也大幅提升,分别提升4.6和2.7倍.Cu_xO负载富氧型TiO_2微球光催化性能增强归因于富氧缺陷和Cu_xO电子转移助催化剂的协同作用.其中,富氧缺陷使得TiO_2价带边上移,拓宽可见光吸收范围,Cu_xO电子转移助剂引入界面电荷转移和多电子氧还原过程,加速光生电子利用率,促进光生电荷分离.该策略也为开发其他高效异质结光催化剂提供参考.     

激光剥蚀高分辨电感耦合等离子体质谱的表面成像技术在钢板线状缺陷分析中的应用探讨

采用激光剥蚀高分辨电感耦合等离子体质谱(LA-HR-ICPMS)技术得到与钢铁材料表面线状缺陷及缺陷周围正常部位的上万个元素质谱信号,与实际样品位置信息比对,各信号与样品表面原始位置相对应,反映样品表面各成分的二维统计分布信息。用该表面成像技术获得的钢板表面线状缺陷区域元素分布结果与电子探针X射线显微分析（EPMA）、激光剥蚀飞行时间质谱（LA-TOF-MS）分析结果一致。该方法具有激发斑点适中、微损、原位分析、检测限低、二维成像直观显示的特点,解决了传统表面微区分析技术检测限偏高、激发斑点过小的问题,可作为表面线状缺陷异常元素甄别的有力工具,为寻找缺陷成因、改进工艺提供依据。     

细乳液聚合法制备磁性复合微球及其表征

在制备超细Fe3O4 磁性粒子的基础上 ,以 3种低分子量聚合物Disperbyk 1 0 6、Disperbyk 1 0 8和Disperbyk 1 1 1为Fe3O4 微粒在单体相中的分散稳定剂 ,采用细乳液聚合法制备了平均粒径为 3 40nm的PS Fe3O4 磁性复合微球 .详细研究了分散剂种类对细乳液聚合制备磁性复合微球的影响 ,并采用XRD、TGA和TEM等手段对磁性复合微球的形态、结构及磁响应性等进行了表征 .实验结果证明分散剂的选择对磁性复合微球的成功制备起着至关重要的作用 ,兼具酸性和碱性功能基的分散剂Disperbyk 1 0 6具有更好的分散和稳定效果 .TEM结果表明 ,所制备的复合微球具有一些缺陷 ,而缺陷处往往是Fe3O4 磁性粒子聚集的地方     

胶体光子晶体的平面介电常数缺陷

为引入特殊的光学性质,通常需要在三维光子晶体中人为可控地引入缺陷.通过改变局部结构单元的尺寸或介电常数,相应地引入给体或受体掺杂,带来不同的缺陷态.以前文献报道的向胶体光子晶体中引入缺陷,常会因为同时引入尺寸和介电常数掺杂,给掺杂性质的界定带来困难.本文中,我们结合对流自组装法和L-B膜法,在实心二氧化硅微球组成的三维光子晶体内引入尺寸相同的二氧化硅空心球(与实心球相比具有不同折光率)组成的单层平面缺陷,或者在空心球晶体内引入实心球缺陷层,构成实心-空心-实心或空心-实心-空心的三明治结构,在不破坏整体晶格的同时,在三维胶体光子晶体中引入单一的平面介电常数缺陷.     

ZrO2氧空位显微结构的高分辨电镜研究

基于透射电镜X射线能谱仪得到的微区成分信息及高分辨电子显微结构信息,构建具有氧空位缺陷的ZrO2晶体结构模型,用200 kV透射电子显微镜的参数进行高分辨实验像的多片层法模拟计算,观察分析了ZrO2多晶材料样品的晶格缺陷.沿[001]方向的二维晶格像及相应的傅立叶变换像显示出ZrO2样品的晶格缺陷.将计算机模拟结果与高分辨实验像进行比较,结果表明计算机模拟像的衬度及周期性与实验像之间符合良好.根据晶体结构的缺陷模型和模拟计算,阐明了氧空位缺陷引起的实验像衬度的变化.通过高分辨电子显微观察结果及计算机模拟结果,揭示了陶瓷ZrO2多晶材料样品晶格中氧空位的存在.     

化合物半导体异质外延层中的缺陷

本文报道了用MBE方法在Si(100)上生成GaAs和用MOCVD方法在GaAs(100)上生成CdTe的异质外延层中的某些缺陷。用JEM-4000EX和JEM-200CX电镜观察,电子束沿晶体的[011]方向入射,观察到的晶体缺陷运用高分辨像和选区衍射技术进行研究和分析。结果表明CdTe/GaAs中主要缺陷是失配位错及微孪晶,而在GaAs/Si中还含有反相无序。     

模拟海洋大气环境中NdFeB(M35)初期腐蚀行为特征

研究模拟海洋大气环境中NdFeB(M35)初期的腐蚀行为.SEM观察表明,该材料初期腐蚀阶段,表面腐蚀过程存在3种代表性类型:Ⅰ)液滴同时覆盖富Nd相和磁性相,富Nd相先发生腐蚀;Ⅱ)液滴覆盖磁性相,磁性相腐蚀沿晶界扩展;Ⅲ)液滴在缺陷附近形成,腐蚀沿缺陷扩展.时间延长,局部腐蚀区相互连接,整体呈现晶界和富Nd相先行腐蚀,磁性相腐蚀相随其后.EDS分析给出腐蚀表面Na、Cl元素的分布,从而明确了腐蚀微电池的形成及腐蚀微电池点位变化是NdFeB(M35)腐蚀的外因.     

共轭聚合物微纳晶的制备与表征及其在场效应晶体管器件中的应用

导电聚合物是20世纪70年代发展起来的一个新兴研究领域,因其在有机光电子学中诱人的应用前景备受关注.但是,目前大部分的聚合物光电器件都是基于薄膜构筑的,大量的缺陷及无规的分子排列不利于我们对材料本征性能的评估及高性能光电器件的构筑.有机单晶具有分子长程有序、低缺陷和无晶界等优点,是用来解决这些问题的最佳选择,但是高质量聚合物单晶的获得一直都是一个挑战性的问题.本文综述了目前有关共轭聚合物微纳晶的制备、表征及其在场效应晶体管器件应用中的研究进展,并对共轭聚合物微纳晶材料与器件的发展前景和面临的一些问题做了简要的讨论.     

Density functional calculation of transition metal cluster energy surfaces

A quantum field mechanics of an electron subsystem in 3D physical space as the topology of compact atomic clusters with spontaneously broken local canonical symmetry is used for investigation of different types of microdefects in the condensed state of transition metals. The theory is illustrated with results of calculation of small compact Fe_n clusters (n = 2, 6, 14).     

Investigation of structural transformation in ripening cotton fiber by the methods of positron annihilation

The microstructure of cotton fiber (sort 175-F, 4 type) at various ripeness stages has been investigated by measuring the spectra of positron life-time and the angular correlation of annihilation radiation. It has been established that the macro strength (breaking load) depends on the concentration and sizes of microdefects (radius less than 10 Å) in amorphous interfibrillar areas. These defects can be studied by registering the characteristics of positron and positronium atom decay and which are hard to reach by traditional physical methods for the analysis of the cotton fiber structure.     

Stearate as a green corrosion inhibitor of magnesium alloy ZE41 in sulfate medium

The efficiency of stearate as a corrosion inhibitor for magnesium alloy ZE41 has been studied in sodium sulfate medium, employing electrochemical techniques like potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of polarization study imply that stearate functions as a mixed-type corrosion inhibitor with a predominant anodic control. The adsorption of stearate on alloy surface is found to obey the Langmuir adsorption isotherm. The proposed inhibition mechanism involved adsorption of stearate onto metal surface, followed by precipitation of magnesium stearate within the microdefects of Mg(OH)₂ surface film which enhanced the barrier effect of an otherwise porous partially protective film.     

Stretching temperature and direction dependency of uniaxial deformation mechanism in overstretched polyethylene

In order to elucidate microscopic deformation behavior at different locations in isotropic semicrystalline polymers, the structural evolution of a preoriented high‐density polyethylene sample during tensile deformation at different temperatures and along different directions with respect to the preorientation was investigated by means of combined in situ synchrotron small‐angle X‐ray scattering (SAXS) and wide‐angle X‐ray diffraction (WAXD) techniques. For samples stretched along preorientation, two situations were found: (1) at 30 °C, the sample broke after a moderate deformation, which is accomplished by the slippage of the microfibrils; (2) at 80 and 100 °C, fragmentation of original lamellae followed by recrystallization process was observed resulting in new lamellar crystals of different thickness depending on stretching temperature. For samples stretched perpendicular or 45° with respect to the preorientation, the samples always end up with a new oriented lamellar structure with the normal along the stretching direction via a stress‐induced fragmentation and recrystallization route. The thickness of the final achieved lamellae depends only on stretching temperature in this case. Compared to samples stretched along the preorientation direction, samples stretched perpendicular and 45° with respect to the preorientation direction showed at least several times of maxima achievable stress before macroscopic failure possibly due to the favorable occurrence and development of microdefects in those lamellar stacks with their normal parallel to the stretching direction. This result might have significant consequence in designing optimal procedure to produce high performance polyethylene products from solid state. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 716–726     

Contributions to the Chemistry of the Binary Compounds of the Transition Elements

Phase and structural relationships of the sulfur, selenium, and tellurium compounds of the 4d and 5d transition elements of groups IV to VII of the periodic system are discussed. Homologous elements behave very similarly with respect to the chalcogens, and this is particularly the case for niobium and tantalum, and for molybdenum and tungsten. However, zirconium, niobium, and molybdenum have a greater tendency towards formation of chalcogen-poor phases than their homologues hafnium, tantalum, and tungsten. Subchalcogenides are known only for zirconium and niobium. The number of phases and the tendency towards formation of solid solutions are considerably smaller among the tellurides than among the sulfides and selenides. The crystal structures of the telluride phases also differ from those of the sulfide and selenide phases of analogous composition. In addition, a review of the phase and structural relationships of the arsenic and antimony compounds of the 4d and 5d transition elements of groups V to VII is given.     

常温常压下吡咯及其衍生物的镍催化加氢反应考察

为进一步研究常温常压下吡咯及其衍生物的镍催化加氢反应,我们对试剂吡咯、吡咯烷和吡咯烷酮做了相应的催化加氢实验。并采用电镜（TEM-HREM）、X射线衍射（XRD）对Ni基催化剂的形貌、结构、加氢活性和超声波对其影响进行了检测,同时还用紫外吸收光谱、气相色谱等对加氢产物进行了分析考察。结果表明超声波能促进镍基催化剂活性,使镍微晶(111)晶面间距增大1.5%、并保持高分散态。常温常压下纳米镍基催化剂对吡咯、吡咯烷和吡咯烷酮的加氢反应显示一定的催化活性;吡咯加氢首先生成吡咯烷,进而使环打开生成低碳烃、氨等产物,总反应为零级,符合表面接触反应特征。     

Semiconductor quantum dots and metal nanoparticles: syntheses,optical properties,and biological applications

We review the syntheses, optical properties, and biological applications of cadmium selenide (CdSe) and cadmium selenide–zinc sulfide (CdSe–ZnS) quantum dots (QDs) and gold (Au) and silver (Ag) nanoparticles (NPs). Specifically, we selected the syntheses of QDs and Au and Ag NPs in aqueous and organic phases, size- and shape-dependent photoluminescence (PL) of QDs and plasmon of metal NPs, and their bioimaging applications. The PL properties of QDs are discussed with reference to their band gap structure and various electronic transitions, relations of PL and photoactivated PL with surface defects, and blinking of single QDs. Optical properties of Ag and Au NPs are discussed with reference to their size- and shape-dependent surface plasmon bands, electron dynamics and relaxation, and surface-enhanced Raman scattering (SERS). The bioimaging applications are discussed with reference to in vitro and in vivo imaging of live cells, and in vivo imaging of cancers, tumor vasculature, and lymph nodes. Other aspects of the review are in vivo deep tissue imaging, multiphoton excitation, NIR fluorescence and SERS imaging, and toxic effects of NPs and their clearance from the body. Figure Semiconductor quantum dots and metal nanoparticles have extensive applications, e.g., in vitro and in vivo bioimaging Tamitake Itoh and Abdulaziz Anas contributed equally to this article.     

纳米粒子的精准组装

纳米材料由于其独特的光、电、磁、力学等性质,成为了构建功能材料与器件的理想基元。实现纳米粒子的精确组装,是探究粒子之间的耦合聚集性质和制备宏观功能器件的基础。但是由于纳米粒子的小尺寸以及在溶液中运动的随机性与复杂性,精准控制纳米粒子组装体的形貌以及在空间中的相对位置仍存在巨大挑战。为了将纳米粒子组装成理想的有序结构,许多控制粒子组装的策略与方法得到发展。本文首先概述了纳米粒子自组装的控制方法与典型形貌,着重分析了影响粒子精准排布的因素与控制方法,并对纳米粒子及其组装体的光学性质与器件应用的最新研究进展进行了讨论,最后对目前纳米粒子精准组装所面临的挑战以及未来发展的方向进行了展望。     

电流变液中悬浮颗粒的体积与形状的变化

基于偶极近似,运用电极化方法,定量研究了电流变液中悬浮颗粒在外电场作用下其体积和形状的变化,并计算了其体积和形状的相对变化率.研究结果表明:悬浮颗粒的体积和形状的相对变化率均与电场强度的平方成正比,并与ER本身的性质有关.一般情况下,颗粒的体积和形状的相对变化率分别为8.4%和12.5%,对总体积变化率的贡献为1.68%.这种变化对于ER系统的电涨和电热都作出了贡献,仅当将颗粒当作刚性球时,其自由能才与电场强度的平方成正比.     

Applications of Thermal Analysis and Coupled Techniques in Pharmaceutical Industry

Thermal analysis methods are well-established techniques in research laboratories of pharmaceutical industry. The robustness and sensitivity of instrumentation, the introduction of automation and of reliable software according to the industrial needs widened considerably the areas of applications in the last decade. Calibration of instruments and validation of results follow the state of the art of cGMP as for other analytical techniques. Thermal analysis techniques are especially useful for the study of the behavior of the poly-phasic systems drug substances and excipients and find a unique place for new delivery systems. Since change of temperature and moisture occur by processing and storage, changes of the solid state may have a considerable effect on activity, toxicity and stability of compounds. Current requirements of the International Conference of Harmonisation for the characterization and the quantitation of polymorphism in new entities re-enforce the position of thermal analysis techniques. This challenging task needs the use of complementary methods. Combined techniques and microcalorimetry demonstrate their advantages. This article reviews the current use of thermal analysis and combined techniques in research and development and in production. The advantage of commercially coupled techniques to thermogravimetry is emphasized with some examples. This revised version was published online in August 2006 with corrections to the Cover Date.