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91.
Based on the self-ordering behavior of ionic liquids on solid surface, a gold ion containing ionic liquid was employed to obtain a uniform pattern of gold nanoparticles on Si substrate. Using this catalytic pattern, super-dense, centimetre long, well-crystallized and vertically-aligned ZnS nanowire arrays were then generated. It was found that the densely-packed gold nanoparticles played a key role in the nanowire alignment. Furthermore, the field-emission measurements show that the present ultralong ZnS nanowires arrays possess a low turn-on field of 3.69 V μm(-1) and a high field-enhancement factor of 1215.4, indicating they are valuable field emitters. 相似文献
92.
Koren K Dmitriev RI Borisov SM Papkovsky DB Klimant I 《Chembiochem : a European journal of chemical biology》2012,13(8):1184-1190
Ir(III)-porphyrins are a relatively new group of phosphorescent dyes that have potential for oxygen sensing and labeling of biomolecules. The requirement of two axial ligands for the Ir(III) ion permits simple linkage of biomolecules by a one-step ligand-exchange reaction, for example, using precursor carbonyl chloride complexes and peptides containing histidine residue(s). Using this approach, we produced three complexes of Ir(III)-octaethylporphyrin with cell-penetrating (Ir1 and Ir2) and tumor-targeting (Ir3) peptides and studied their photophysical properties. All of the complexes were stable and possessed bright, long-decay (unquenched lifetimes exceeding 45 μs) phosphorescence at around 650 nm, with moderate sensitivity to oxygen. The Ir1 and Ir2 complexes showed positive staining of a number of mammalian cell types, thus demonstrating localization similar to endoplasmic reticulum and ATP- and temperature-independent intracellular accumulation (direct translocation mechanism). Their low photo- and cytotoxicity allows intracellular oxygen to be probed. 相似文献
93.
Noboru Yoshikawa Guoqiang XieZiping Cao Dmitri V. Louzguine 《Journal of the European Ceramic Society》2012,32(2):419-424
An Fe3O4 powder compact was irradiated with a 2.45 GHz microwave single-mode applicator at the magnetic field maximum position. Selectively heated regions (hot spot region) having several hundred micrometers to millimeter scale were formed. They exhibited metallic color. The SEM/EDX observations showed no appreciable difference in the compositions between the hot spot regions and the matrix. However, micro-XRD revealed that the hot spot region had a larger fraction of FeO than the matrix did, although the major consisting phase was Fe3O4 with a little Fe2O3. TEM observations indicated that the observed hot spot regions comprise these oxide phases separated in nano-sized grains, which agrees with our previous report. The larger fraction of FeO phase and flat surface might be related with the metallic color of the hot spot region. Their formation mechanisms and phase constitution were discussed. 相似文献
94.
Ding Wang Dmitri Donetsky Seungyong Jung Gregory Belenky 《Journal of Electronic Materials》2012,41(11):3027-3030
Minority carrier lifetime in long-wave infrared (LWIR) type?II InAs/GaSb superlattices was studied using the optical modulation response (OMR) technique in wide ranges of excitation and temperature. The measured carrier lifetime was found to increase superexponentially with decreasing excitation power density below the level of 1?mW/cm2 to 2?mW/cm2. The phenomenon was qualitatively explained by the presence of shallow trapping centers. 相似文献
95.
Xi Wang Xinqiang Cao Laure Bourgeois Hasigaowa Guan Shimou Chen Yeteng Zhong Dai‐Ming Tang Huiqiao Li Tianyou Zhai Liang Li Yoshio Bando Dmitri Golberg 《Advanced functional materials》2012,22(13):2682-2690
A new facile route to fabricate N‐doped graphene‐SnO2 sandwich papers is developed. The 7,7,8,8‐tetracyanoquinodimethane anion (TCNQ?) plays a key role for the formation of such structures as it acts as both the nitrogen source and complexing agent. If used in lithium‐ion batteries (LIBs), the material exhibits a large capacity, high rate capability, and excellent cycling stability. The superior electrochemical performance of this novel material is the result from its unique features: excellent electronic conductivity related to the sandwich structure, short transportation length for both lithium ions and electrons, and elastomeric space to accommodate volume changes upon Li insertion/extraction. 相似文献
96.
From time immemorial people dealt with size reduction processes (mill, mineral liberation, etc.). As time has passed industrial units for comminution processes have become larger and more sophisticated, but still they perform with low efficiencies [1], [2] and [3]. The strength of a particle is one of its most crucial characteristics due to the mechanical stresses experienced by each particle within an industrial unit. This is because the final size of particles is mostly dependant on the strength distribution of the raw material [4]. In this present study, the ability of a number of statistical formulations to accurately describe the strength distribution of particles was examined. Additionally, selected equations were analyzed and a general expression including the effect of the material and particle size was developed. A number of approaches to define particle strength were considered, and strength in terms of crushing force was chosen. Particle strength in terms of force and in terms of energy was also compared and found to be size independent. Finally, particle strength in terms of stress was examined and compared to the particle strength in terms of force.The ability to describe the compression strength distribution will significantly improve the accuracy of the comminution processes simulation, design and optimization. 相似文献
97.
The synthesis of polymer-stabilized nanoparticles (PSNPs) can be successfully carried out using intermatrix synthesis (IMS) technique, which consists in sequential loading of the functional groups of a polymer with the desired metal ions followed by nanoparticles (NPs) formation stage. After each metal-loading-NPs-formation cycle, the functional groups of the polymer appear to be regenerated. This allows for repeating the cycles to increase the NPs content or to obtain NPs with different structures and compositions (e.g. core-shell or core-sandwich). This article reports the results on the further development of the IMS technique. The formation of NPs has been shown to proceed by not only the metal reduction reaction (e.g. Cu0-NPs) but also by the precipitation reaction resulting in the IMS of PSNPs of metal salts (e.g. CuS-NPs). 相似文献
98.
Dmitri N. Muraviev Maria Isabel Pividory José Luis Montañez Soto Salvador Alegret 《溶剂提取与离子交换》2013,31(5):731-745
Abstract Extractant‐assisted synthesis of platinum and palladium polymer‐stabilized metal nanoparticles (PSMNP) was carried out for the first time. The synthesis included the following sequential steps: a) loading of extractant (tributyl‐phosphine oxide, TBPO) with the desired metal ion; b) preparation of a membrane “cocktail” by mixing a metal‐containing extractant, solution of the polymer (PVC or polysulfone) and plastisizer; c) membrane deposition and metal reduction inside the membrane (intermatrix synthesis of PSMNP) by using either a chemical or an electrochemical reduction technique. The electro conductivity of the resulting polymer‐metal nanocomposite membrane appeared by several orders of magnitude higher than that of the metal‐free polymer. The mass‐exchange properties of PSMNP‐containing membranes were shown to depend on both the type of the polymer and the membrane deposition technique. 相似文献
99.
Bhari Mallanna Nagaraja Dmitri A. Bulushev Sergey Beloshapkin Sarayute Chansai Julian R. H. Ross 《Topics in Catalysis》2013,56(18-20):1686-1694
Ni/K–MgO–ZrO2 catalysts for dry reforming of methane, with a range of Mg/Zr ratios and each containing about 10 wt% Ni, were prepared via Ni nitrate impregnation on MgO–ZrO2 supports synthesized by co-precipitation using K2CO3. It was found that a proportion of the potassium of the precipitant remained in the samples and improved the stability of the catalysts in the reaction. It was also shown that reduction of the catalysts at 1,023 K without calcination in air is necessary for stable and high activity; calcination in air at 1,073 K gives a deterioration of the catalytic properties, leading to rapid deactivation during the reaction. The order of the CH4 conversions of the reduced catalysts after 14 h on stream was as follows: Ni/K–Mg5Zr2 ~ Ni/K–Mg ≥ Ni/K–Mg2Zr5 ? Ni/K–Zr. A catalyst with 0.95 wt% K on MgO–ZrO2 with a Mg:Zr mole ratio of 5:2 showed the best resistance to deactivation. Experiments in a microbalance system showed that there was only negligible coke deposition on the surface of this sample. This behaviour was attributed to the presence of Ni nanoparticles with a diameter of less than 10 nm located on a MgO/NiO solid solution shell doped by K ions; this in turn covers a core of tetragonal ZrO2 and/or a MgO/ZrO2 solid solution. This conclusion was supported by EDS/TEM, XPS, XRD and H2 chemisorption measurements. 相似文献
100.
In Wireless Mesh Networks (WMNs), mobile clients may experience frequent handoffs due to the relatively small transmission range of the mesh routers. Each handoff may lead to packet delays and/or packet losses, which limits the performance of real-time applications over WMNs. In this work, we propose BASH—a Backhaul-Aided Seamless Handoff scheme. BASH takes advantage of the wireless backhaul feature of WMNs, and allows a mobile station to directly access the backhaul channel to probe the neighboring mesh routers. Our work shows that by utilizing the wireless backhaul, BASH (1) reduces the probing latency and, thus, the Layer-2 handoff latency; (2) allows partial overlap of the Layer-2 and Layer-3 handoffs, reducing the overall handoff latency; and (3) shortens the authentication latency by utilizing the transitivity of trust relationship. The experimental results show that BASH achieves an average Layer-2 handoff of 8.9 ms, which supports real-time applications during the handoff. 相似文献