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61.
Iron oxide nanoparticles made from the thermal decomposition method are highly uniform in all respects (size, shape, composition and crystallography), making them ideal candidates for many bioapplications. The surfactant coating on the as-synthesized nanoparticles renders the nanoparticles insoluble in aqueous solutions. For biological applications nanoparticles must be water soluble. Here we demonstrate the phase transfer of our nanoparticles with the biocompatible copolymer Pluronic F127. Transmission electron microscopy, Fourier transform infrared spectroscopy and dynamic light scattering indicate that the nanoparticles are coated discretely. Magnetic measurements show that the nanoparticles remain superparamagnetic with saturation magnetization ∼96% of the maximum theoretical value. 相似文献
62.
Christopher Batchelor-McAuley Craig E Banks Andrew O Simm Timothy G J Jones Richard G Compton 《Chemphyschem》2006,7(5):1081-1085
The benefits of using nanoparticle-modified electrodes are exemplified through the electrochemical detection of protons and/or hydrogen. It is shown that a palladium-nanoparticle-modified boron-doped diamond allows voltammetric information relating to the relative roles played by the surface and the bulk metal to be obtained for the proton-hydrogen system at palladium surfaces which is not accessible using palladium macroelectrodes or microelectrodes. 相似文献
63.
Dextran-modified iron oxide nanoparticles 总被引:1,自引:0,他引:1
Dextran-modified iron oxide nanoparticles were prepared by precipitation of Fe(Ⅱ) and Fe(Ⅲ) salts with ammonium hydroxide by two methods. Iron oxide was precipitated either in the presence of dextran solution, or the dextran solution was added after precipitation. In the second method, the iron oxide particle size and size distribution could be controlled depending on the concentration of dextran in the solution. The nanoparticles were characterized by size-exclusion chromatography, transmission electron microscopy and dynamic light scattering. Optimal conditions for preparation of stable iron oxide colloid particles were determined, The dextran/iron oxide ratio 0-0,16 used in precipitation of iron salts can be recommended for synthesis of nanoparticles suitable for biomedical applications, as the colloid does not contain excess dextran and does not coagulate. 相似文献
64.
The dry etching characteristics of transparent and conductive indium-zinc oxide (IZO) films have been investigated using an inductively coupled high-density plasma. While the Cl2-based plasma mixture showed little enhancement over physical sputtering in a pure argon atmosphere, the CH4/H2/Ar chemistry produced an increase of the IZO etch rate. On the other hand, the surface morphology of IZO films after etching in Ar and Ar/Cl2 discharges is smooth, whereas that after etching in CH4/H2/Ar presents particle-like features resulting from the preferential desorption of In- and O-containing products. Etching in CH4/H2/Ar also produces formation of a Zn-rich surface layer, whose thickness (∼40 nm) is well-above the expected range of incident ions in the material (∼1 nm). Such alteration of the IZO layer after etching in CH4/H2/Ar plasmas is expected to have a significant impact on the transparent electrode properties in optoelectronic device fabrication. 相似文献
65.
We have used x-ray fluorescence analysis to study the elemental composition of gunshot residues from smooth-bore and rifled-bore
guns. We have established that it is possible to differentiate between types of projectiles (jacketed/lead), types of primers
(corrosive/noncorrosive), and types of propellant powders (black/smokeless) by analysis of the elemental composition of the
gunshot residues. We have shown that the mercury content in gunshot residues on the surface of the object carrying the residues
steadily decreases as storage time increases. Despite this fact, mercury can be preserved as a component of gunshot residues
on the object (cotton cloth) under room conditions for more than 45 days.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 320–325, May–June, 2006. 相似文献
66.
Hiroshi Onishi 《Catalysis Surveys from Japan》2002,6(1-2):1-8
The present account describes first time examples of scanning tunneling microscope (STM) visualization of reaction intermediates on a metal oxide surface. The topographic response of reactant-adsorbed TiO2(110) surfaces to a temperature increment or to a pressure increment was monitored as a sequence of STM images. Acetates thermally decomposing to ketene were resolved in a temperature-jump STM observation. The kinetics of the acetate consumption was determined on the number of acetates resolved in the microscope images and agreed with the macroscopic rate law of ketene production. A pressure-jump study revealed how a chemisorbed carboxylate (RCOO-) is exchanged by another carboxylate (R'COO-) supplied from the ambient vapor phase. An impinging R'COOH was immobilized on the top of a RCOO- and then squeezed itself into the monolayer of the RCOO-. One of the carboxylates in the squeezed state returned to the vapor phase via the immobilized state. 相似文献
67.
Methods to synthesize magnetic Fe3O4 nanoparticles and to modify the surface of particles are presented in the present investigation. Fe3O4 magnetic nanoparticles were prepared by the co-precipitation of Fe3+ and Fe2+, NH3·H2O was used as the precipitating agent to adjust the pH value, and the aging of Fe3O4 magnetic nanoparticles was accelerated by microwave (MW) irradiation. The obtained Fe3O4 magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and vibrating sample magnetometer (VSM). The average size of Fe3O4 crystallites was found to be around 8–9 nm. Thereafter, the surface of Fe3O4 magnetic nanoparticles was modified by stearic acid. The resultant sample was characterized by FT-IR, scanning electron microscopy (SEM), XRD, lipophilic degree (LD) and sedimentation test. The FT-IR results indicated that a covalent bond was formed by chemical reaction between the hydroxyl groups on the surface of Fe3O4 nanoparticles and carboxyl groups of stearic acid, which changed the polarity of Fe3O4 nanoparticles. The dispersion of Fe3O4 in organic solvent was greatly improved. Effects of reaction time, reaction temperature and concentration of stearic acid on particle surface modification were investigated. In addition, Fe3O4/polystyrene (PS) nanocomposite was synthesized by adding surface modified Fe3O4 magnetic nanoparticles into styrene monomer, followed by the radical polymerization. The obtained nanocomposite was tested by thermogravimetry (TG), differential scanning calorimetry (DSC) and XRD. Results revealed that the thermal stability of PS was not significantly changed after adding Fe3O4 nanoparticles. The Fe3O4 magnetic fluid was characterized using UV–vis spectrophotometer, Gouy magnetic balance and laser particle-size analyzer. The testing results showed that the magnetic fluid had excellent stability, and had susceptibility of 4.46×10−8 and saturated magnetization of 6.56 emu/g. In addition, the mean size d (0.99) of magnetic Fe3O4 nanoparticles in the fluid was 36.19 nm. 相似文献
68.
In this work, the optical and structural properties of high k materials such as tantalum oxide and titanium oxide were studied by spectroscopic ellipsometry, where a Tauc-Lorentz dispersion model based in one (amorphous films) or two oscillators (microcrystalline films) was used. The samples were deposited at room temperature by radio frequency magnetron sputtering and then annealed at temperatures from 100 to 500 °C. Concerning the tantalum oxide films, the increase of the annealing temperature, up to 500 °C does not change the amorphous nature of the films, increasing, however, their density. The same does not happen with the titanium oxide films that are microcrystalline, even when deposited at room temperature. Data concerning the use of a four-layer model based on one and two Tauc-Lorentz dispersions is also discussed, emphasizing its use for the detection of an amorphous incubation layer, normally present on microcrystalline films grown by sputtering. 相似文献
69.
比浊法测定酸性镀铜液中微量氯离子 总被引:1,自引:0,他引:1
以乙二醇为增溶剂,硝酸银作沉淀剂,采用氯化银比浊法,在不分离硫酸铜的条件下,直接测定酸性镀铜液中微量氯离子。测定波长为440 nm,线形范围为0~50μg/25 mL,其表观摩尔吸光系数ε=1.3×105,方法检出限为0.035μg/mL,该法用于测定酸性镀铜液中微量氯离子在不同水平的加标回收率为95.4%~104.5%。结果表明,该法准确,快速,简便,其它的常见离子无干扰。 相似文献
70.
用硼氢化钠作还原剂,制备出两种相对稳定的含银纳米颗粒的水溶胶,用透射电镜(TEM)和光学吸收谱对这些颗粒进行了表征.当被还原的银离子较少时,所形成的银纳米颗粒较小,吸收峰呈现二极等离子体共振吸收峰.当被还原的银离子较多时,银纳米颗粒尺寸变大,并出现二极和四极共振吸收峰.在Ag纳米颗粒形成后,对其溶液稀释,发现其峰形保持不变,而峰位会出现红移,最大红移量可达到10 nm.透射电镜研究表明,低浓度溶胶中的Ag纳米颗粒尺寸较为均匀,平均直径12 nm.高浓度溶胶中的纳米颗粒尺寸呈双尺寸分布特点,少量颗粒直径小于14 nm,大部分颗粒直径大于20 nm. 相似文献