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Ravindra Kumar Jha, Prasanta Kumar Guha
WS2 nanosheets have been synthesized by ultrasonication in a binary mixture of acetone and 2-propanol, with a volume ratio of 80:20. Hansen solubility parameters were taken into consideration as part of the process. These nanosheets have been characterized by electron microscopy, atomic force microscopy, and x-ray diffraction, along with spectroscopy such as ultraviolet-visible spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. The nanosheets were further used as a sensing material to fabricate a humidity sensor on interdigitated aluminum electrodes, realized over Si/SiO2 substrate using a conventional photolithography technique...
October 24, 2016: Nanotechnology
F Tumino, C S Casari, M Passoni, C E Bottani, A Li Bassi
Two-dimensional (2D) ZnO structures have been deposited on the Au(111) surface by means of the pulsed laser deposition technique. In situ scanning tunneling microscopy and scanning tunneling spectroscopy measurements have been performed to characterize morphological, structural and electronic properties of 2D ZnO at the nanoscale. Starting from a sub-monolayer coverage, we investigated the growth of ZnO, identifying different atomic layers (up to the fifth). At low coverage, we observed single- and bi-layer nanocrystals, characterized by a surface moiré pattern that is associated to a graphene-like ZnO structure...
October 24, 2016: Nanotechnology
Damián Rodríguez Sartori, Cristian R Lillo, Juan J Romero, María Laura Dell Arciprete, Alejandro Miñán, Mónica Fernández Lorenzo de Mele, Mónica C Gonzalez
Grafting of polyethylene glycol (PEG) to ultrasmall photoluminescent silicon dots (SiDs) is expected to improve and expand the applications of these particles to aqueous environments and biological systems. Herein we report a novel one-pot synthesis of robust, highly water compatible PEG-coated SiDs (denoted as PEG-SiDs) of (3.3 ± 0.5) nm size. The nanoparticles' synthesis is based on the liquid phase oxidation of magnesium silicide using PEG as reaction media and leading to high PEG density grafting. PEG-SiDs enhanced photophysical, photosensitising, and solution properties in aqueous environments are described and compared to those of 2 nm size PEG-coated SiDs with low PEG density grafting (denoted as PEG-NHSiDs) obtained from a multistep synthesis strategy...
October 24, 2016: Nanotechnology
Moussa Biaye, Ewa Zbydniewska, Thierry Mélin, Dominique Deresmes, Guillaume Copie, Fabrizio Cleri, Neralagatta Sangeetha, Nicolas Decorde, Benoit Viallet, Jérémie Grisolia, Laurence Ressier, Heinrich Diesinger
Nanoparticle assemblies with thiol-terminated alkyl chains are studied by conducting atomic force microscopy (c-AFM) regarding their use as strain gauges for touch-sensitive panels. Current-force spectroscopy is used as a characterization tool complementary to the macroscopic setup since it allows a bias to be applied to a limited number of junctions, overcoming the Coulomb blockade energy and focusing on the contact electromechanics and the transport mechanism across the ligand. First, transition voltage spectroscopy is applied with varying force to target the underlying tunneling mechanism by observing whether the transition between the ohmic and exponential current-voltage behavior is force-dependent...
October 24, 2016: Nanotechnology
J R Yuan, X H Yan, Y Xiao, Y D Guo, C J Dai
Motivated by recent measurement of the magnetism and conductance of the oxygen-assisted Pt nanojunctions, we performed first principle calculations of the magnetic order and electronic transport by explicitly including fully relativistic effects. Our results show that the spin alignment is a cycloidal spiral feature attributed to the Dzyaloshinskii-Moriya interaction, which indicates that the observed magnetism in experiments is of noncollinear nature. The oxygen concentration is the responsible for the switching of the rotational sense of the spiral magnetic order found in oxygen-assisted Pt nanojunctions...
October 24, 2016: Nanotechnology
Fan-Ching Chien, Yang-Hong Dai, Chiung Wen Kuo, Peilin Chen
Flexible polymer nanopillar substrates were used to systematically demonstrate cell alignment and migration guided by the directional formation of focal adhesions. The polymer nanopillar substrates were constructed to various height specifications to provide an extensive variation of flexibility; a rectangular arrangement created spatial confinement between adjacent nanopillars, providing less spacing in the horizontal and vertical directions. Three polymer nanopillar substrates with the diameter of 400 nm and the heights of 400, 800, and 1200 nm were fabricated...
October 24, 2016: Nanotechnology
Sori Lee, Byeonghak Park, Jun Sik Kim, Tae-Il Kim
The patterning of high-resolution-featured deep-nanoscale structures with a high aspect ratio (AR) has received increasing attention in recent years as a promising technique for a wide range of applications, including electrical, optical, mechanical and biological systems. Despite extensive efforts to develop viable nanostructure fabrication processes, a superior technique enabling defect-free, high-resolution control over a large area is still required. In this review, we focus on recent important advances in the designs and processes of high-resolution nanostructures possessing a high AR, including hierarchical and 3D patterns...
October 24, 2016: Nanotechnology
Richard A Boucher, Jürgen Bauch, Dietmar Wünsche, Gerhard Lackner, Anindya Majumder
X-ray detectors based on metal-oxide semiconductor field effect transistors couple instantaneous measurement with high accuracy. However, they only have a limited measurement lifetime because they undergo permanent degradation due to x-ray beam exposure. A field effect transistor based on carbon nanotubes (CNTs), however, overcomes this drawback of permanent degradation, because it can be reset into its starting state after being exposed to the x-ray beam. In this work the CNTs were deposited using a dielectrophoresis method on SiO2 coated p-type (boron-doped) Si substrates...
October 24, 2016: Nanotechnology
Yongxin Guan, Yangyang Feng, Yanping Mu, Ling Fang, Huijuan Zhang, Yu Wang
Known as an excellent energy storage material, ZnMn2O4 has a wide range of applications in supercapacitors. In this report, a special sandwich-like structure of ZnMn2O4/C has been first designed and synthesized via a simple hydrothermal method and subsequent calcinations. The designed special sandwich-like structure can benefit ion exchange and remit the probable volume changes during a mass of electrochemical reactions. Furthermore, the porous carbon nanosheets, derived from low-cost glucose, can effectively increase ion flux...
October 24, 2016: Nanotechnology
Libin Yang, Kunyang Wang, Gu Du, Wenxin Zhu, Liang Cui, Chengxiao Zhang, Xuping Sun, Abdullah M Asiri
Hydrogen has been considered as an ideal energy carrier for replacing fossil fuels to mitigate global energy crises. Hydrolysis of sodium borohydride (NaBH4) is simple and effective for hydrogen production but needs active and durable catalysts to accelerate the kinetics. In this paper, we demonstrate that cobalt phosphide nanowall arrays supported on carbon cloth (CoP NAs/CC) efficiently catalyze the hydrolytic dehydrogenation of NaBH4 with an activation energy of 42.1 kJ mol(-1) in alkaline media. These monolithic CoP NAs/CC show a maximum hydrogen generation rate of [Formula: see text] and are robust with superior durability and reusability...
October 21, 2016: Nanotechnology
Dureid Qazzazie, Mohammad Halhouli, Olena Yurchenko, Gerald Urban
The lack of performance of graphene-based electrocatalysts for oxygen reduction (ORR) is a major concern for fuel cells which can be mastered using nanocomposites. This work is highlighted by the optimization of nitrogen(N)-doped graphene/carbon nanotubes (CNTs) nanocomposite's ORR performance examined by galvanostatic measurements in realistically approached glucose half-cells. Obtained results mark an essential step for the development of nanocarbon-based cathodes, as we specifically evaluate the electrode performance under real fuel cell conditions...
October 21, 2016: Nanotechnology
Shiliang Wang, Qiulai Huang, Yueqin Wu, Han Huang
Single-crystalline α-Al2O3 nanobelts were synthesized by high-temperature chemical vapor deposition in a high-purity H2 atmosphere. The crystalline planes for the upper and side surfaces of the nanobelts were [Formula: see text] and [Formula: see text] and the orientations along height, length and width directions were [Formula: see text] [Formula: see text] and [Formula: see text] respectively. The formation of such a unique structure was dependent on the strong reducing atmosphere used in the growth process, and the deactivation of the [Formula: see text] plane by hydrogen could be the primary cause...
October 21, 2016: Nanotechnology
Wang-Taek Hwang, Misook Min, Hyunhak Jeong, Dongku Kim, Jingon Jang, Daekyung Yoo, Yeonsik Jang, Jun-Woo Kim, Jiyoung Yoon, Seungjun Chung, Gyu-Chul Yi, Hyoyoung Lee, Gunuk Wang, Takhee Lee
We investigated the electrical characteristics and the charge transport mechanism of pentacene vertical hetero-structures with graphene electrodes. The devices are composed of vertical stacks of silicon, silicon dioxide, graphene, pentacene, and gold. These vertical heterojunctions exhibited distinct transport characteristics depending on the applied bias direction, which originates from different electrode contacts (graphene and gold contacts) to the pentacene layer. These asymmetric contacts cause a current rectification and current modulation induced by the gate field-dependent bias direction...
October 21, 2016: Nanotechnology
Jie Chen, Jens H Walther, Petros Koumoutsakos
The increasing power density and the decreasing dimensions of transistors present severe thermal challenges to the design of modern microprocessors. Furthermore, new technologies such as three-dimensional chip-stack architectures require novel cooling solutions for their thermal management. Here, we demonstrate, through transient heat-dissipation simulations, that a covalently bonded graphene-carbon nanotube (G-CNT) hybrid immersed in water is a promising solution for the ultrafast cooling of such high-temperature and high heat-flux surfaces...
October 19, 2016: Nanotechnology
Mingwei Wan, Xiaoxu Li, Lianghui Gao, Weihai Fang
The self-assembly of phospholipid-coated gold nanorods (GNRs) was investigated by coarse-grained molecular dynamics simulations. We predict that in addition to the formation of deformed vesicles encapsulating GNRs with diverse orientations, the lipid-coated GNRs can form a semi-ring attached to an excess vesicle phase, a branch with excess vesicle phase, a ring phase, a branch phase, a stack phase, and a vortex phase. The morphologies of the lipid-GNR complexes depend on the lipid/GNR molar ratio and the interaction strength between the nanorod surface and the lipid head groups...
October 19, 2016: Nanotechnology
Genmao Huang, Lian Duan, Yunlong Zhao, Yunge Zhang, Guifang Dong, Deqiang Zhang, Yong Qiu
Thin-film transistors (TFTs) with high mobility and good uniformity are attractive for next-generation flat panel displays. In this work, solution-processed polycrystalline zinc tin oxide (ZTO) thin film with well-ordered microstructure is prepared, thanks to the synergistic effect of water addition and step heating. The step heating treatment other than direct annealing induces crystallization, while adequate water added to precursor solution further facilitates alloying and densification process. The optimal polycrystalline ZTO film is free of hierarchical sublayers, and featured with an increased amount of ternary phases, as well as a decreased fraction of oxygen vacancies and hydroxides...
October 19, 2016: Nanotechnology
Mini Mol Menamparambath, Kihyuk Yang, Hyeong Hoon Kim, Oh Seung Bae, Mun Seok Jeong, Jae-Young Choi, Seunghyun Baik
Silver nanowires (Ag NWs) have received considerable attention for flexible transparent conductive films (TCFs) since they provide a relatively low sheet resistance at a high transmittance. However, the diffuse light scattering, haze, has been regarded as a hurdle to achieve clarity of films. Here we revisit the Mie scattering theory to calculate the extinction and scattering coefficients of Ag NWs which were employed to estimate haze of TCFs. The theory predicted a decrease in haze with a decrease in Ag NW diameter which was supported by experimental investigations carried out using Ag NWs with 5 different diameters (17...
October 19, 2016: Nanotechnology
Jia-Jing Wu, You-Rong Tao, Lei Fan, Zhong-Yu Wu, Xing-Cai Wu, Yuan Chun
The nonlinear absorption and nonlinear refractive properties of ZrSe3 nanoflakes were studied with a 6.5 ns pulse laser at 532 nm. Open-aperture Z-scan curves reveal that ZrSe3 nanoflakes have a strong reverse saturable absorption property, and close-aperture Z-scan curves show that ZrSe3 dispersions possess a positive nonlinear refractive index caused by self-focusing. The nonlinear absorption coefficient, the nonlinear refraction coefficient, and the figures of merit (FOM) of ZrSe3 dispersed in water with linear transmittances of 0...
October 17, 2016: Nanotechnology
Yuxiang Qin, Yongyao Wang, Yi Liu, Xiaojuan Zhang
The limited surface area and compacted configuration of silicon nanowires (SiNWs), which are made by one-step metal-assisted chemical etching (MACE) go against target gas diffusion and adsorbtion for gas sensing application. To harvest suitable gas sensitivity and fast response-recovery characteristics, an aligned, rough SiNW array with loose configuration and high surface area was fabricated by a two-step etching process. The MACE technique was first employed to fabricate a smooth SiNW array, and then a KOH post-etching method was developed to roughen the NW surface further...
October 17, 2016: Nanotechnology
Snober Ahmed, John Brockgreitens, Ke Xu, Abdennour Abbas
With increasing biomedical and engineering applications of selenium nanospheres (SeNS), new efficient methods are needed for the synthesis and long-term preservation of these nanomaterials. Currently, SeNS are mostly produced through the biosynthesis route using microorganisms or by using wet chemical reduction, both of which have several limitations in terms of nanoparticle size, yield, production time and long-term stability of the nanoparticles. Here, we introduce a novel approach for rapid synthesis and long-term preservation of SeNS on a solid microporous support by combining a mild hydrothermal process with chemical reduction...
October 17, 2016: Nanotechnology
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