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151.
电场驱动的高分子凝胶 总被引:1,自引:0,他引:1
本文较系统地阐述了电场驱动的高分子水凝胶、有机凝胶的响应机理,并扼要介绍了此类凝胶应用的最新进展。 相似文献
152.
电弧-AES法测定金属硅中12个杂质元素 总被引:2,自引:0,他引:2
用直流电弧粉末法在氩气气氛中摄谱,消除硅带干扰,采用铍为内标,直接测定金属硅中12个杂质元素,此法较化学光谱法具有操作简便、快速,试剂耗量少;较化学法和分光光度法更加优越,能同时测定12个元素,更能反映金属硅的真实含量。 相似文献
153.
本文概述了瓦斯煤尘爆炸火焰光谱实验研究的重要性,我们在弱爆炸和探测器小视场角的条件下,利用自己研制的多波道仪,在一端开口的Φ200cm×2900cm大型管道里,得到了CH4、空气和煤尘的混合物在不同状态下,特征波长λ等于0.8875、1.000、1.505、2.801和4.346微米(μ)的绝对辐射强度及其有关的变化规律,对结果进行了分析讨论,并与国外实验结果进行了对比,根据测量λ=4.346μ绝对辐射强度和我们选择的黑体辐射模型,获得了爆炸火焰的温度,该项研究不仅在工业中具有重要意义,而且对燃烧和化学动力学的研究也具有参考价值。 相似文献
154.
This paper presents detailed numerical calculations of the dielectrophoretic force in traps designed for single-cell trapping. A trap with eight planar electrodes is studied for spherical and ellipsoidal particles using the boundary element method (BEM). Multipolar approximations of orders one to three are compared with the full Maxwell stress tensor (MST) calculation of the electrical force on spherical particles. Ellipsoidal particles are also studied, but in their case only the dipolar approximation is available for comparison with the MST solution. The results show that a small number of multipolar terms need to be considered in order to obtain accurate results for spheres, even in the proximity of the electrodes, and that the full MST calculation is only required in the study of non-spherical particles. 相似文献
155.
A. Hussain C.W. Ahn H.J. Lee I.W. Kim J.S. Lee S.J. Jeong S.K. Rout 《Current Applied Physics》2010,10(1):305-310
We have fabricated lead-free Bi0.5(Na0.75K0.25)0.5TiO3 (BNKT) ceramics by a conventional process (CP) and reactive templated grain growth (RTGG) methods. The effect of grain orientation on structure, dielectric, complex impedance and electrical properties was investigated. The phase formation and grain morphology of BNKT ceramics were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. High dielectric constant and low dielectric loss was observed for grain oriented (textured) BNKT ceramics. Complex impedance, temperature dependent ac and dc conductivity were performed to explore the conduction behavior of the prepared BNKT ceramics. 相似文献
156.
Zhi-Hai Zhang Kang-Xian GuoBin Chen Rui-Zhen WangMin-Wu Kang Shuai Shao 《Superlattices and Microstructures》2010
The optical absorption coefficients and the changes in the refractive index in GaAs/AlGaAs parabolic quantum dots(QDs) with applied electric and magnetic fields are studied in detail. Analytical expressions for the linear and nonlinear intersubband absorption coefficients and refractive index changes are obtained by using a compact density matrix approach and an iterative procedure. Finally, the calculated results show the incident optical intensity, the frequencies of the confined potential of the QDs and the applied electric and magnetic fields have a great influence on the optical absorption coefficients and refractive index changes in this system. 相似文献
157.
László Janovák 《Applied Surface Science》2010,256(9):2809-1312
Poly(acrylamide) [poly(AAm)] and poly(N-isopropyl-acrylamide) [poly(NIPAAm)] based gel films containing Au nanoparticles (d = 14 ± 2.5 nm) were synthesized. Monomers and cross-linker were added to a gold nanodispersion, and after the addition of the initiator, polymer films were prepared on the surface of an interdigital microelectrode by photopolymerization. In the course of the syntheses the gold concentration of the films was constant (10.8 μg/cm2) and the volume fraction of Au nanoparticles (?Au) in the polymer gel films varied in the range of 0.58-85.3%. Poly(AAm)-based films swell when the temperature increases: due to a temperature shift of 15 °C the Au plasmon absorption maximum at λ = ∼532 nm was shifted towards shorter wavelengths by 16.6 nm (blue shift) through the swelling of the polymer gel film. In the case of poly(NIPAAm) the temperature-induced shrinking resulted in a red shift, namely the maximum was shifted by 18.07 nm by a temperature shift of 15 °C. In the case of both composites, the electric conductivity of the samples was shown to increase with increasing Au particle concentration. In the case of the poly(AAm)-based composite containing ?Au = 0.85 gold the resistance of the film spread on the surface of the electrode was 0.16 MΩ at 25 °C and 0.66 MΩ at 50 °C, i.e. the conductivity of the sample decreased with increasing temperature. The opposite effect is observed in the case of the poly(NIPAAm)-based composite: as temperature is raised, the resistance of the composite abruptly drops at the point of collapse of the NIPAAm gel (it is 0.28 MΩ at 32 °C and only 0.021 MΩ at 35 °C). This thermosensitive effect was detectable only at sufficiently high Au contents (?Au = 0.85) in both gels. 相似文献
158.
In the work, short multi-walled carbon nanotubes (S-CNTs) were synthesized by chopping conventional μm-long multi-walled carbon nanotubes (L-CNTs) under ultrasonication in H2SO4/HNO3 mixed acids. A comparative electrochemical investigation performed in 6 M KOH solution demonstrated that a specific capacitance (SC) of ca. 14.6 μF cm−2 was delivered by the S-CNTs with the specific surface area (SSA) of 207 m2 g−1, much larger than that of ca. 10.1 μF cm−2 for the L-CNTs with the SSA of 223 m2 g−1, the reason for which was that S-CNTs with two open ends, due to good ion penetrability, provided more entrances for electrolyte ions to access the inner surface easily through their shorter inner pathway so as to enhance their SSA utilization and geometric SC. The surface structure disruption of S-CNTs, owing to ultrasonication and oxidation during chopping process, deteriorated their electronic conductivity and resulted in an inferior power property in contrast to L-CNTs. 相似文献
159.
In the present study, the buffering effect of magnetite nanoparticles (Fe3O4) dispersed in an aqueous solution on the local pH value is investigated. It manifests itself in the fact that when some amount of acid or base is added to the solution then the solution near the nanoparticles surface becomes, respectively, less acidic and less alkaline than it is expected. It is the result of both the local electrostatic field, which represents the electric double layer at the surface of magnetic nanoparticles and the magnetic field around the nanoparticles. The magnetite nanoparticles exhibit very low toxicity and they are becoming increasingly important for new biomedical applications related to their effects on chemical reactions in body tissues and cells. The question arises, how strong are these effects at the nanoscale? The strength of the buffering property of magnetite nanoparticles is investigated both theoretically and experimentally by the direct measurement of the local pH value of a magnetic nanoparticles suspension. The theoretical model is based on stochastic equations describing the ions diffusing in the neighborhood of the electric double layer of the magnetic material. The electric double layer is modeled with the help of the Poisson–Boltzmann model. It is directly shown that both the electrostatic field and the magnetic field are responsible for the observed local changes of the pH value with respect to the bulk pH value. 相似文献
160.
Abstract The photovoltaic effect in Cu2s-CdS heterojunction has been the subject of study by a large number of investigators. Proper heat treatment of the junction plays crucial role in optimizing the performance of the heterojunction. In this paper, after a brief review of the work on Cu2S-CdS heterojunctions, the profile of copper in CdS as a function of heat treatment will be discussed. The diffusion of copper from Cu2S into CdS has been studied at various temperatures, by radioactive tracer methods. This has a bearing on the spectral response of the Cu2S-CdS cells as a function of heat treatment. 相似文献