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1.
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.  相似文献   

2.
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.  相似文献   

3.
Bo  Xu  Yi-hu  Song  Yong-gang  Shang  Guan  郑强 《高分子科学》2006,(3):299-306
Melt extrusion was used to prepare binary nanocomposites of ethylene copolymers and organoclay and trinary nanocomposites of low-density polyethylene (LDPE), ethylene copolymer and organoclay. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the structure of the clay phase and the morphology of the nanocomposites. Influences of the comonomer in the copolymer and the content of the copolymer on the morphology of the resulting nanocomposites were discussed. The binary and the trinary composites may form intercalated or exfoliated structures depending on the interaction between the copolymer and the clay layers and the content of the copolymer.  相似文献   

4.
5.
常温常压下吡咯及其衍生物的镍催化加氢反应考察   总被引:2,自引:0,他引:2  
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。  相似文献   

6.
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.  相似文献   

7.
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。  相似文献   

8.
This article presents an overview of the interaction in solution of certain plant and algal polysaccharides with cations and also of their interaction in admixture with other polysaccharides and proteins. The mechanism of gelation of pectin and alginate in the presence of calcium ions is discussed together with the specific binding of potassium ions to kappa carrageenan and its influence on the coil–helix transition. The associative and segregative phase behaviour that is encountered in aqueous solutions of mixed polysaccharide systems is considered together with the formation of the soluble and insoluble complexes in mixtures of polysaccharides and proteins.  相似文献   

9.
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.  相似文献   

10.
多弧离子镀TiN与不同金属基材间的接触界面与表面特性   总被引:1,自引:0,他引:1  
用多弧离子镀技术在不同金属基材上进行TiN镀膜实验,制备了TiN/Fe、 TiN/Cu和TiN/Cr/Cu复合膜.借助扫描电子显微镜(SEM)、 X射线衍射仪(XRD)和光电子能谱(XPS),研究了TiN与Fe、 Cu和Cr/Cu三种不同衬底接触界面的形貌、结构及其表面特性.SEM观察发现,在一定离子镀膜条件下, TiN涂层可与Fe、 Cu和Cr/Cu金属基材形成均匀平整的接触界面,在铜基上TiN界面清晰,在Fe与Cr/Cu界面有明显的层状晶界微结晶分布.XRD分析显示, Fe、 Cu和Cr/Cu表面生成的薄膜都包含TiN、 Ti2N等多晶相,在Cr/Cu界面还包含Ti-Cr的金属间化合物.XPS结果表明,表面除了TiN膜外,还生成TiO2和TiOxNy等氧化膜.Ar+刻蚀5 min后, TiO2消失, TiOxNy减少, TiN则呈增加趋势.TiN与Cr/Cu界面形成明显的Ti-Cr和Cr-Ni互扩散层,这有助于增强薄膜附着力,形成较牢固的TiN涂层.  相似文献   

11.
《Mendeleev Communications》2021,31(5):593-604
In this focus overview, the main types and directions of engineering, methods and techniques of intensification of chemical process systems (CPS) and process optimization of energy- and resource-efficient processes for the representative production of titanium compounds, mining waste processing systems, electrochemical coating technologies, combined technologies for the treatment of industrial effluents and energy-and resource-efficient technologies for cleaning soils from petroleum and chemical pollution products are reviewed. The following issues have been discussed: methods of complex assessment of production energy efficiency and software and information support for automated synthesis of optimal energy-efficient regenerative heat exchange systems using pinch analysis; methods and algorithms for fractal-statistical characteristics analysis of nonstationary gas flows in complex gas pipelines; methods of ecological and economic optimization of production, infrastructure supply chains; methods for assessing and preventing the dangerous environmental impact assessment of chemical pollution; organization and logistics management of business processes engineering for improving the energy efficiency of plants; engineering of problem oriented computer systems, heuristic-computational models and algorithms for intelligent integrated logistics support of the equipment life cycle; engineering developments in the field of digital transformation of energy-efficient CPS and technological production systems; application of methods for optimizing reliability factors optimization, digitalized risk and safety management in the engineering of energy- and resource efficient CPS.  相似文献   

12.
L—赖氨酸锌细胞生物学和生物学实验研究   总被引:6,自引:3,他引:3  
研究了L-赖氨酸锌对健康大鼠血液及骨髓中细胞的影响,并与对照组进行了比较。结果表明,本品对健康鼠血液中红细胞,血小板,淋巴细胞、中性白细胞和单核细胞及骨髓多染红细胞中的微核数等均无显著性影响,另外大鼠伤寒沙门氏菌的致突变实验显示L-赖氨酸锌未引起大鼠伤寒沙门氏组氨酸缺陷型变异菌株的回复突变,而健康小儿血液各项生化指标的变化,揭示本品可显示提高血液中碱性磷酸酶和红细胞水平,对白细胞的增殖有促进作用,但对乳酸脱氢酶、谷丙转氨酶等无显著性影响。  相似文献   

13.
Thermal Analysis in Combustion Research   总被引:2,自引:0,他引:2  
Thermal analysis is widely used in combustion research for both fundamental and practical investigations. Efficient combustion of solid fuels in power plants requires understanding of properties and behavior of fuel and ash under a wide range of conditions. At the Department of Chemical Engineering, Technical University of Denmark, thermogravimetric analysis and differential scanning calorimetry are applied in order to investigate various aspects of combustion and gasification processes: pyrolysis, char reactivity and ash melting behavior. This paper shows examples of the application of simultaneous thermal analysis in these three research areas, and it demonstrates the flexibility of this technique in combustion research. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

14.
Surface chemistry of zirconium   总被引:1,自引:0,他引:1  
This article presents an overview of the surface chemistry of zirconium, focusing on the relationship of what is known from model studies and how this connects to current and future applications of Zr-based materials. The discussion includes the synergistic nature of adsorbate interactions in this system, the role of impurities and alloying elements, and temperature-dependent surface–subsurface transport. Finally, some potential uses of zirconium and its alloys for biomedical and nanolithographic applications are presented.  相似文献   

15.
CdS and CdS/ZnS core-shell structure nano particles were synthesized in micro emulsion, and characterized by X-ray diffraction(XRD), transmission electron microscopy (TEM), UV absorption spectra and PL. The average diameter of CdS was about 3.3 nm, and CdS/ZnS core-shell structure was confirmed by XRD and UV. Considering the optical properties of CdS/ZnS core-shell structure nanoparticles which have different ZnS shell thickness, the UV absorption edge of CdS/ZnS becomes as lightred-shift with the thickness of ZnS layer increasing, and the absorption of shortwave band is strongly enhanced at the same time. The PL spectra indicate that ZnS shell layer can greatly eliminate surface defects of CdS nanoparticles and make its band-edge directed recombination increased, and the luminous efficiency of CdS is improved greatly when it has appropriate shell thickness.  相似文献   

16.
Unsaturated polyester resin (UPR)/acrylate-terminated polyurethane (ATPU)/organo-modified montmorillonite (OMMT) nanocomposites were prepared by the in situ intercalative polymerization method. Samples were prepared by the sequential mixing, i.e. mixture of the ATPU and styrene (S) and OMMT were prepared in the first step; UPR was then added to the pre-intercalates of ATPU/S/OMMT. Results indicate that the mechanical properties and thermal properties of UPR/ATPU/OMMT nanocomposites greatly depend on the amount of ATPU and OMMT. Results show that the addition of ATPU could increase the impact strength of UPR/ATPU composites, but the tensile strength, flexural strength and heat resistance of the materials are obviously decreased. When the weight ratio between UPR, ATPU and OMMT were 82:15:3, the impact strength and heat distortion-temperature of nanocomposite were greatly improved, meanwhile there was little change for other properties of the nanocomposites. The synergistic enhancement effects of ATPU and OMMT on the composites were observed. The structures and morphology of the composites were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy.  相似文献   

17.
18.
NMR technologies such as relaxation, self-diffusion coefficient and other NMR methods were reviewed. The results of NMR measurements, especially, on 1H, 13C, 19F-NMR spectra and quadrupolar echo of 2H-NMR spectra on self-assembled properties and structures have been obtained. The investigations on the self-assembly of amphiphiles and the transition of self assembled structures were introduced and the determination of NMR measurements on micelles, vesicles and microemulsions was summed.  相似文献   

19.
The kinetic parameters of the exothermic decomposition reaction of the title compound in a temperature-programmed mode have been studied by means of DSC. The DSC data obtained are fitted to the integral, differential and exothermic rate equations by linear least-squares, iterative, combined dichotomous and least-squares methods, respectively. After establishing the most probable general expression of differential and integral mechanism functions by the logical choice method, the corresponding values of the apparent activation energy (Ea), pre-exponential factor (A) and reaction order (n) will be obtained by the exothermic rate equation. The results show that the empirical kinetic model function in differential form and the values of Ea and A of this reaction are (1-α)0.44, 230.4 kJ/mol and 1018.16 s-1, respectively. With the help of the heating rate and obtained kinelic parameters, the kinetic equation of the exothermic decomposition reaction process of the title compound is proposed. The critical temperature of thermal explosion of the compound is 302.6℃. The above-mentioned kinetic parameters are quite useful for analyzing and evaluating the stability and thermal change rule of the title compound.  相似文献   

20.
测定了浙江省宁波、海宁部分地区223例3-4岁健康幼儿同一个体头发和全血铅和锌含量,并研究两类样本两种微量元素的相关性。发现除血锌男女性别间含量差异不明显外,发中的锌、铅,全血中的铅均有显著的性别差异;无论是头发或是全血,男性或女性铅和锌均呈负相关且大多数有显著性;发铅和血铅男性和女性均呈显著正相关,而发锌与血锌女性也呈显著相关。本文还求出发铅与血铅、发锌与血锌含量间的一元线性回归方程。  相似文献   

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