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991.
Nguyen XS Tay CB Fitzgerald EA Chua SJ 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(8):1204-8, 1125
The fabrication of a p-shell/n-core coaxial nanorod ZnO homojunction light-emitting diode by inexpensive solution method is demonstrated. The p-type conductivity of the ZnO shell arises from the incorporation of potassium while the n-type conductivity of the core is due to unintentional doping. 相似文献
992.
Jeong Hwan ChunKi Tae Park Dong Hyun JoJi Young Lee Sang Gon KimSun Hee Park Eun Sook LeeJy-Young Jyoung Sung Hyun Kim 《International Journal of Hydrogen Energy》2011,36(14):8422-8428
In this study, a gas diffusion layer (GDL) was modified to improve the water management ability of a proton exchange membrane fuel cell (PEMFC). We developed a novel hydrophobic/hydrophilic double micro porous layer (MPL) that was coated on a gas diffusion backing layer (GDBL). The water management properties, vapor and water permeability, of the GDL were measured and the performance of single cells was evaluated under two different humidification conditions, R.H. 100% and 50%. The modified GDL, which contained a hydrophilic MPL in the middle of the GDL and a hydrophobic MPL on the surface, performed better than the conventional GDL, which contained only a single hydrophobic MPL, regardless of humidity, where the performance of the single cell was significantly improved under the low humidification condition. The hydrophilic MPL, which was in the middle of the modified GDL, was shown to act as an internal humidifier due to its water absorption ability as assessed by measuring the vapor and water permeability of this layer. 相似文献
993.
Conventionally, there have been three basic ways of research on H2 production from H2O-splitting with solar energy: photo-catalytic, photo-electrochemical and thermochemical. Among them the thermal dissociation of H2O has been considered the most efficient, because it is a single step energy conversion process and gives much higher conversion efficiency than those resulted from other methods. However, the major stumbling block of thermal dissociation of H2O has been the requirement of a high dissociation temperature which causes problems both with materials for the reactor and with energy conversion efficiency for the process. In this study, we show that the dissociation temperature can be drastically lowered when H2O is thermally dissociated on solid acid materials. A probable mechanism of the thermal H2O-splitting on solid acid materials is also presented, based on some experimental results of this study and reports in the literature. 相似文献
994.
995.
In this letter, we report a novel method of visualizing nanoscale friction in space and time using ultrafast electron microscopy (UEM). The methodology is demonstrated for a nanoscale movement of a single crystal beam on a thin amorphous membrane of silicon nitride. The movement results from the elongation of the crystal beam, which is initiated by a laser (clocking) pulse, and we examined two types of beams: those that are free of friction and the others which are fixed on the substrate. From observations of image change with time we are able to decipher the nature of microscopic friction at the solid-solid interface: smooth-sliding and periodic slip-stick friction. At the molecular and nanoscale level, and when a force parallel to the surface (expansion of the beam) is applied, the force of gravity as a (perpendicular) load cannot explain the observed friction. An additional effective load being 6 orders of magnitude larger than that due to gravity is attributed to Coulombic/van der Waals adhesion at the interface. For the case under study, metal-organic crystals, the gravitational force is on the order of piconewtons whereas the static friction force is 0.5 μN and dynamic friction is 0.4 μN; typical beam expansions are 50 nm/nJ for the free beam and 10 nm/nJ for the fixed beam. The method reported here should have applications for other materials, and for elucidating the origin of periodic and chaotic friction and their relevance to the efficacy of nano(micro)-scale devices. 相似文献
996.
The development of a general approach for the nondestructive chemical and biological functionalization of graphene could expand opportunities for graphene in both fundamental studies and a variety of device platforms. Graphene is a delicate single-layer, two-dimensional network of carbon atoms whose properties can be affected by covalent modification. One method for functionalizing materials without fundamentally changing their inherent structure is using biorecognition moieties. In particular, oligopeptides are molecules containing a broad chemical diversity that can be achieved within a relatively compact size. Phage display is a dominant method for identifying peptides that possess enhanced selectivity toward a particular target. Here, we demonstrate a powerful yet benign approach for chemical functionalization of graphene via comprehensively screened phage displayed peptides. Our results show that graphene can be selectively recognized even in nanometer-defined strips. Further, modification of graphene with bifunctional peptides reveals both the ability to impart selective recognition of gold nanoparticles and the development of an ultrasensitive graphene-based TNT sensor. We anticipate that these results could open exciting opportunities in the use of graphene in fundamental biochemical recognition studies, as well as applications ranging from sensors to energy storage devices. 相似文献
997.
998.
999.
Liang Yu Yan Weifeng Li Xiao Feng Fan Li Wei Yuan Chen Jer‐Lai Kuo Lain‐Jong Li Sang Kyu Kwak Yuguang Mu M. B. Chan‐Park 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(1):110-118
Heparin sodium salt is investigated as a dispersant for dispersing single‐walled carbon nanotubes (SWNTs). Photoluminescence excitation (PLE) spectroscopy is used for identification and abundance estimation of the chiral species. It is found that heparin sodium salt preferentially disperses larger‐diameter Hipco SWNTs. When used to disperse CoMoCAT nanotube samples, heparin has a strong preference for (8,4) tubes, which have larger diameter than the predominant (6,5) in pristine CoMoCAT samples. PLE intensity due to (8,4) tubes increases from 7% to 60% of the total after threefold extractions. Computer modeling verifies that the complex of (8,4) SWNTs and heparin has the lowest binding energy amongst the four semiconducting species present in CoMoCAT. Network field‐effect transistors are successfully made with CoMoCAT/heparin and CoMoCAT/sodium dodecylbenzene sulfonate (SDBS)–heparin (x3), confirming the easy removability of heparin. 相似文献
1000.
A peroxynitrite (ONOO(-)) biosensor has been developed through the preparation of a new manganese-[poly-2,5-di-(2-thienyl)-1H-pyrrole)-1-(p-benzoic acid)] (Mn-pDPB) complex. DPB monomer was first synthesized and polymerized for the purpose of providing a polymer backbone for complex formation with Mn(2+) ion. The Mn-pDPB complex was characterized via Magnetomotive Force (MMF) simulation, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. The complex selectively enhanced the reduction process of ONOO(-) which was used as the analytical signal for chronoamperometric detection. A polyethyleneimmine (PEI) layer was coated on the complex surface to increase selectivity and stability. The chronoamperometric calibration plot showed the hydrodynamic range of 2.0 × 10(-8)-5.0 × 10(-7) M. The detection limit was determined to be 1.9 (±0.2) × 10(-9) M based on S/N = 3. The microbiosensor, fabricated on a 100 μm diameter Pt tip, was applied in a real rat plasma sample for the detection of spiked concentrations of ONOO(-). The reliability and long-term stability of the microbiosensor was also examined with YPEN-1 cells in vitro, and the results shown were promising. 相似文献