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81.
在混合密度泛函B3LYP理论下,用3-21G基函数对有限长扶手椅形单壁碳纳米管(4,4)、(5,5)和(6,6)的构型进行优化和分子静电势计算.结果表明:除近核区域为正常的正电势外,碳纳米管结构模型的管内和管外为负电势区域;在碳纳米管结构模型的管内,管心处均出现负电势的最小值,且负电势的绝对值随着碳纳米管的曲率降低而增大,管心轴线上静电势的变化随碳纳米管的曲率降低而减少,带电粒子流比较容易通过纳米管. 相似文献
82.
《Electroanalysis》2006,18(24):2451-2457
This paper describes a layer‐by‐layer (LBL) self‐assembly process of chitosan (CTS) and gold nanoparticles (Au) on the pretreated negatively charged glassy carbon (GC) electrode to fabricate electrochemistry immunosensor with a nontoxic biomimetic interface, which provided an environment similar to a native system and allowed more freedom in orientation for immobilization of carcinoembryonic antibody (anti‐CEA) to monitor carcinoembryonic antigen (CEA). UV‐vis spectroscope, atomic force microscopy (AFM), and cyclic voltammetric (CV) measurements were used to follow the multilayer film formation. The performance of the biominetic interface and factors influencing the assay system were investigated in detail. The differential pulse voltammetry (DPV) current response is used for the CEA concentration assay. The dynamic range was from 0.50 to 80.00 ng mL?1 with a detection limit of 0.27 ng mL?1 at 3σ. In addition, the experiment results indicate that immobilization described in this proposed method exhibits a good sensitivity, selectivity, and stability. 相似文献
83.
Chemical techniques were employed to synthesize CdS nanoparticles embedded in polymer (PEG 300) and sol-gel silica matrices. Systematic growth of particles (radius 3–9 nm) was obtained by adjusting post-deposition annealing temperature and time to examine the dependence of surface-state–related luminescence on particle size. Photoluminescence (PL) peak energy showed a linear dependence with a gentle slope in the weak confinement region and a steep slope in the strong confinement region, the divergence being observed near the excitonic Bohr radius for CdS. The empirical relation proposed for the weak confinement region could be used for estimating chemically prepared CdS nanoparticle size with a high degree of reliability from PL peak energy. 相似文献
84.
Kyung Hwa Hong Jong Lyoul Park In Hwan Sul Ji Ho Youk Tae Jin Kang 《Journal of Polymer Science.Polymer Physics》2006,44(17):2468-2474
Polyvinyl alcohol (PVA) nanofibers containing Ag nanoparticles were prepared by electrospinning PVA/silver nitrate (AgNO3) aqueous solutions, followed by short heat treatment, and their antimicrobial activity was investigated for wound dressing applications. Since PVA is a water soluble and biocompatible polymer, it is one of the best materials for the preparation of wound dressing nanofibers. After heat treatment at 155 °C for 3 min, the PVA/AgNO3 nanofibers became insoluble, while the Ag+ ions therein were reduced so as to produce a large number of Ag nanoparticles situated preferentially on their surface. The residual Ag+ ions were reduced by subsequent UV irradiation for 3 h. The average diameter of the Ag nanoparticles after the heat treatment was 5.9 nm and this value increased slightly to 6.3 nm after UV irradiation. It was found that most of the Ag+ ions were reduced by the simple heat treatment. The PVA nanofibers containing Ag nanoparticles showed very strong antimicrobial activity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2468–2474, 2006 相似文献
85.
《Electroanalysis》2006,18(6):613-620
The interaction of malachite green (MG) with double‐stranded DNA (dsDNA) in pH 7.0 Britton–Robinson (B–R) buffer solution was investigated by electrochemical and spectrophotometric methods. Within the potential scan range of ?1.0 to +1.5 V (vs. SCE), MG has two oxidative peaks at 0.547 V and 0.833 V and one reductive peak at 0.362 V on cyclic voltammogram at the scan rate of 0.20 V/s. After the addition of dsDNA into the MG solution, the oxidative peak current at 0.547 V decreases obviously. The electrochemical parameters, such as the charge transfer coefficient (α), the surface reaction rate constant (ks) and the diffusion coefficient (D), were calculated and compared between in the absence and presence of dsDNA. The results show that these parameters of MG after adding dsDNA have greatly changed, which indicates that an electrochemical active complex was formed. The interaction mechanisms of MG with dsDNA are discussed in some details from the electrochemistry and UV‐vis spectrophotometry. The reduction of the peak current of MG after adding dsDNA was further used for the quantification of dsDNA by differential pulse voltammetry (DPV). The linear range for dsDNA is in the range of 10.0–100.0 μg/mL with the linear regression equation as Δip (μA)=0.065+0.0096 C (μg/mL) and the detection limit of 6.0 μg/mL (3σ). The influences of coexisting substances were investigated and artificial samples were determined with satisfactory results. 相似文献
86.
Backman Ulrika Jokiniemi Jorma K. Auvinen Ari Lehtinen Kari E.J. 《Journal of nanoparticle research》2002,4(4):325-335
We have prepared spherical non-agglomerated silver nanoparticles by an evaporation–condensation–dilution/cooling technique. Silver was evaporated from a crucible in a tubular flow reactor. A porous tube diluter was used to quench the carrier gas at the outlet of the reactor to enhance the formation of small particles and to suppress agglomeration and other particle growth mechanisms. The number size distribution of the prepared particles was measured with a differential mobility analyser–condensation nucleus counter combination and the size and the shape of the particles were analysed with transmission electron microscope. The system was modelled using a sectional aerosol dynamics computer code to estimate the importance of different aerosol processes. In all conditions the particles obtained were non-agglomerated and spherical. The mean particle diameter varied from 4 to 10-nm depending on boundary conditions. From the modelling studies it can be concluded that the nucleation rate is the most important parameter controlling the final particle size. 相似文献
87.
We have studied antimony and selenium atomization processes including a chemical matrix modifier (palladium-containing activated
carbon) during their determination by electrothermal atomic absorption spectrometry. We have developed and fine-tuned an experimental
setup for determining the kinetic characteristics (activation energy and frequency factor) for element atomization processes
from measurements in the initial section of the analytical signal. We provide a rationale for the most likely mechanism for
the interactions that occur. The results of the kinetic studies of the atomization processes showed that the modifier we developed
was highly effective, as a result of formation of a thermally stable condensed system C-Pd-A (where A is the analyte).
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 530–534, July–August, 2006. 相似文献
88.
基于超分子结构共掺杂纳米复合薄膜的制备与荧光特性 总被引:5,自引:0,他引:5
为改善功能分了的特性,提出一种基于金属纳米粒子-偶氮染料复合物共掺杂超分子结构功能材料的设计新方法.并依照此方法制备出复合材料,观测了其显微结构,测量了其紫外-可见光吸收,研究了该超分子结构复合体系的荧光特性.实验发现,由于金属银纳米粒子的掺杂,使得超分子结构复合体系中功能分子甲基橙在溶液态体系的荧光强度增强近5倍,而在两种不同结构(共混结构和包覆结构)的薄膜态超分子结构体系中,其荧光强度分别被猝灭15%和20%.研究结果表明,复合膜中采用超分子结构完全能够改善功能分子的特性. 相似文献
89.
90.
Solubility of carbon dioxide in aqueous solutions of sodium chloride: Experimental results and correlation 总被引:2,自引:0,他引:2
The solubility of carbon dioxide in aqueous solutions of sodium chloride was measured in the temperature range from 40 to 160°C, up to 6 mol-kg salt solutions and total pressures up to 10 MPa. Pitzer's(1) equations as well as the Chen and Evans(2) model were used to correlate the new data. Results are reported and compared to literature data and correlations. 相似文献