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Nanotechnology

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https://www.readbyqxmd.com/read/28211793/a-novel-field-emission-microscopy-method-to-study-field-emission-characteristics-of-freestanding-carbon-nanotube-array
#1
Yunhan Li, Yonghai Sun, David Jaffray, John T W Yeow
Field emission (FE) uniformity and mechanism of emitter failure of freestanding carbon nanotube (CNT) arrays have not been well studied due to the difficulty of observing and quantifying FE performance of each emitter in CNT arrays. Herein a field emission microscopy (FEM) method based on Poly(methyl methacrylate) (PMMA) thin film is proposed to study the FE uniformity and CNT emitter failure of freestanding CNT arrays. FE uniformity of freestanding CNT arrays and different levels of FE current contributions from each emitter in the arrays are recorded and visualized...
February 17, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28211792/one-pot-synthesis-of-in-situ-carbon-coated-fe3o4-as-long-life-lithium-ion-battery-anode
#2
Min Liu, Hongyun Jin, Evan Uchaker, Zhiqiang Xie, Ying Wang, Guozhong Cao, Shuen Hou, Jiangyu Li
Fe3O4 has been regarded as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, low cost, and environmental friendliness. In this work, we present a one-pot reducing-composite-hydroxide-mediated (R-CHM) method to synthesize in-situ carbon-coated Fe3O4 (Fe3O4@C) at 280 oC, using Fe(NO3)3·9H2O and PEG800 as raw materials and NaOH/KOH as the medium. The as-prepared Fe3O4 octahedron has an average size of 100 nm in diameter, covered by carbon layer with the thickness of 3 nm , as revealed by FESEM and HRTEM images...
February 17, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28207418/electrical-transport-and-thermoelectric-properties-of-boron-carbide-nanowires
#3
Kazuhiro Kirihara, Masakazu Mukaida, Yoshiki Shimizu
The electrical transport and thermoelectric property of boron carbide nanowires synthesized by a carbothermal method are reported. It is demonstrated that the nanowires achieve a higher Seebeck coefficient and power factor than those of the bulk samples. The conduction mechanism of the nanowires at low temperatures below 300 K is different from that of the sintered-polycrystalline and single-crystal bulk samples. In a temperature range of 200 to 450 K, there is a crossover between electrical conduction by variable-range hopping and phonon-assisted hopping...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28206983/an-immutable-array-of-tio2-nanotubes-to-pressures-over-30-gpa
#4
Yanyan Zhang, Qinglin Wang, Junkai Zhang, Xiaoxin Wu, Yanzhang Ma
We report the successful formation of an immutable array of α-PbO2-phase TiO2 nanotubes by compression of a TiO2 nanotube array in an anatase phase. During compression to 31.3 GPa, the TiO2 nanotubes started to directly transform from an anatase phase to a baddeleyite phase at ~15 GPa and completed the transition at ~23 GPa. Under decompression, the baddeleyite phase transformed to a α-PbO2 phase at 4.6 GPa, which was quenchable to ambient pressure. Notably the tubular array microstructure was retained after the application of ultrahigh pressure and undergoing a series of phase transformations...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28206982/biocompatible-chitosan-nanoparticles-as-an-efficient-delivery-vehicle-for-mycobacterium-tuberculosis-lipids-to-induce-potent-cytokines-and-antibody-response-through-activation-of-%C3%AE-%C3%AE-t-cells-in-mice
#5
Ishani Das, Avinash Padhi, Sitabja Mukherjee, Debi Dash, Santosh Kar, Avinash Sonawane
Activation of cell mediated and humoral immune responses to Mycobacterium tuberculosis (Mtb) are critical for protection and that nanoparticles mediated delivery of antigens are more potent in inducing different immune responses. Herein, we show that mice immunized with Mtb lipid bound chitosan nanoparticles(NPs) induce secretion of prominent type 1 T helper (Th1) and type 2 T helper (Th2) cytokines in lymph node and spleen cells, and also induced significantly higher levels of IgG, IgG1, IgG2 and IgM in comparison to control mice...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28206981/mno2-g-c3n4-nanocomposite-with-highly-enhanced-supercapacitor-performance
#6
Xueting Chang, Xinxin Zhai, Shibin Sun, Danxia Gu, Lihua Dong, Yansheng Yin, Yanqiu Zhu
A novel sandwich-like MnO2/g-C3N4 nanocomposite (NC) based on the integration of high-density MnO2 nanorods (NRs) onto the surfaces of two-dimensional (2D) g-C3N4 sheets has been successfully fabricated through a facile soft chemical route at low temperature. The MnO2/g-C3N4 NC electrode enhanced the supercapacitor (SC) performance, benchmarked against both the bare MnO2 NRs electrode and the MnO2/graphene oxide (GO) NC electrode, exhibiting high specific capacitance of 211 F/g at a current density of 1 A/g, with good rate capacity and cycling stability...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28206980/fast-low-temperature-plasma-reduction-of-monolayer-graphene-oxide-at-atmospheric-pressure
#7
Michal Bodik, Anna Zahoranova, Matej Micusik, Nikola Bugarova, Zdeno Spitalsky, Maria Omastova, Eva Majkova, Matej Jergel, Peter Siffalovic
We report on an ultrafast plasma-based graphene oxide reduction method superior to the conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is of the order of seconds, the presented method is applicable to large-scale production of the reduced graphene oxide layers. The short reduction times are achieved by a high volume power density of plasma which is of the order of 100 W/cm<sup>3</sup>...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28205512/superplastic-behavior-of-silica-nanowires-obtained-by-direct-patterning-of-silsesquioxane-based-precursors
#8
Mustafa Yılmaz, Nicole Wollschläger, Mohammad Nasr Esfahani, Werner Österle, Yusuf Leblebici, B Erdem Alaca
Silica nanowires spanning 10 μm-deep trenches are fabricated from different types of silsesquioxane-based precursors by direct e-beam patterning on silicon followed by release through deep reactive ion etching. Nanowire aspect ratios as large as 150 are achieved with a critical dimension of about 50 nm and nearly rectangular cross-sections. In situ bending tests are carried out inside a scanning electron microscope, where the etch depth of 10 [Formula: see text] provides sufficient space for deformation. Silica NWs are indeed observed to exhibit superplastic behavior without fracture with deflections reaching the full etch depth, about two orders of magnitude larger than the nanowire thickness...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28205511/controllable-quantized-conductance-for-multilevel-data-storage-applications-using-conductive-bridge-random-access-memory
#9
Fekadu Gochole Aga, Jiyong Woo, Jeonghwan Song, Jaehyuk Park, Seokjae Lim, Changhyuck Sung, Hyunsang Hwang
In this paper, we investigate the quantized conduction behavior of conductive bridge random access memory (CBRAM) with varied materials and ramping rates. We report stable and reproducible quantized conductance states with integer multiples of fundamental conductance obtained by optimizing the voltage ramping rate and the Ti-diffusion barrier (DB) at the Cu/HfO2 interface. Owing to controlled diffusion of Cu ions by the Ti-DB and the optimized ramping rate, through which it was possible to control the time delay of Cu ion reduction, more than seven levels of discrete conductance states were clearly observed...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28205510/controlling-second-harmonic-generation-at-the-nanoscale-with-monolithic-algaas-on-alox-antennas
#10
L Carletti, D Rocco, A Locatelli, C De Angelis, V F Gili, M Ravaro, I Favero, G Leo, M Finazzi, L Ghirardini, M Celebrano, G Marino, A V Zayats
We review recent achievements in the field of nanoscale nonlinear AlGaAs photonics based on all-dielectric optical antennas. After discussing the motivation and main technological challenges for the development of an AlGaAs monolithic platform for χ ((2)) nonlinear nanophotonics, we present numerical and experimental investigations of the second-order nonlinear response and physical reasons for high efficiency of second-order nonlinear interactions in the AlGaAs nano-antennas. In particular, we emphasize the role of the dipolar resonances at the fundamental frequency and the multipolar resonances at the second harmonic wavelength...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28205509/anisotropic-mechanical-and-optical-response-and-negative-poisson-s-ratio-in-mo2c-nanomembranes-revealed-by-first-principles-simulations
#11
Bohayra Mortazavi, Masoud Shahrokhi, Meysam Makaremi, Timon Rabczuk
Transition metal carbides include a wide variety of materials with attractive properties that are suitable for numerous and diverse applications. A most recent experimental advance could provide a path toward the successful synthesis of large-area and high-quality ultrathin Mo2C membranes with superconducting properties. In the present study, we used first-principles density functional theory calculations to explore the mechanical and optical response of single-layer and free-standing Mo2C. Uniaxial tensile simulations along the armchair and zigzag directions were conducted and we found that while the elastic properties are close along various loading directions, the nonlinear regimes in stress-strain curves are considerably different...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28205507/a-facile-self-template-strategy-for-synthesizing-1d-porous-ni-c-nanorods-towards-efficient-microwave-absorption
#12
Yanan Zhang, Xingmiao Zhang, Bin Quan, Guangbin Ji, Xiaohui Liang, Wei Liu, Youwei Du
Ni@C composites, which simultaneously possess porous, core-shell and 1D nanostructures have been synthesized with a facile self-template strategy. The precursors were obtained by a hydrothermal process using NiCl2 · 6H2O and nitrilotriacetic acid as the starting material and then annealed at 400 °C, 500 °C, and 600 °C. The Ni@C composites annealed at 500 °C display a nanorod feature with a length of ∼3 μm and diameter of 230-500 nm. In addition, about 3 nm carbon shells and 4 nm Ni cores can be found in Ni@C nanorods...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28195075/stretchable-array-of-metal-nanodisks-on-a-3d-sinusoidal-wavy-elastomeric-substrate-for-frequency-tunable-plasmonics
#13
Di Feng, Hui Zhang, Siyi Xu, Limei Tian, Ningfang Song
Metal nanostructures integrated with soft, elastomeric substrates provide an unusual platform with capabilities in plasmonic frequency tuning of mechanical strain. In this paper, we have prepared a tunable optical device, dense arrays of plasmonic nanodisks on a low-modulus, and high-elongation elastomeric substrate with a three-dimensional (3D) sinusoidal wavy, and their optical characteristics have been measured and analyzed in detail. Since surface plasmon is located and propagates along metal surfaces with sub-wavelength structures, and those dispersive properties are determined by the coupling strength between the individual structures, in this study, a 3D sinusoidal curve elastomeric substrate is used to mechanically control the inter-nanodisk spacing by applying straining and creating a frequency tunable plasmonic device...
February 14, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28192283/economically-attractive-route-for-the-preparation-of-high-quality-magnetic-nanoparticles-by-the-thermal-decomposition-of-iron-iii-acetylacetonate
#14
Fernando B Effenberger, Ricardo A Couto, Pedro K Kiyohara, Giovanna Machado, Sueli H Masunaga, Renato F Jardim, Liane M Rossi
The thermal decomposition (TD) methods are among the most successful in obtaining magnetic nanoparticles with a high degree of control of size and narrow particle size distribution. Here we investigated the TD of iron(III) acetylacetonate in the presence of oleic acid, oleylamine, and a series of alcohols in order to disclose their role and also investigate economically attractive alternatives for the synthesis of iron oxide nanoparticles without compromising their size and shape control. We have found that some affordable and reasonably less priced alcohols, such as 1,2-octanediol and cyclohexanol, may replace the commonly used and expensive 1,2-hexadecanediol, providing an economically attractive route for the synthesis of high quality magnetic nanoparticles...
February 13, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28186002/influence-of-charge-traps-in-carbon-nanodots-on-gas-interaction
#15
Anwesha Mukherjee, Siva Reddy, Buddha Boruah, Abha Misra
The nonlinear electrical characteristics of carbon nanodots (CNDs) has revealed important physical phenomena of charge trapping playing a dominant role in surface interactions. The various functional groups on the surface of the CNDs attract ambient water molecules which in turn act as charge traps and give rise to electrical hysteresis that plays a dominant role in understanding charge transport in the CNDs on surface interactions. The hysteresis in current-voltage response is further utilized to study the interaction of the CNDs with external stimuli, nitrogen dioxide gas...
February 10, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28186001/observation-and-understanding-of-anisotropic-strain-relaxation-in-selectively-grown-sige-fin-structures
#16
Andreas Schulze, Roger Loo, Paul Ryan, Matthew Wormington, Paola Favia, Liesbeth Witters, Nadine Collaert, Hugo Bender, Wilfried Vandervorst, Matty Caymax
The performance of heterogeneous 3D transistor structures critically depends on the composition and strain state of the buffer, channel and source/drain regions. In this paper we used an in-line high resolution X-ray diffraction (HRXRD) tool to study in detail the composition and strain in selectively grown SiGe/Ge fin structures with widths down to 20nm. For this purpose we arranged fins of identical dimensions into larger arrays which were then analyzed using an X-ray beam several tens of micrometer in size...
February 10, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28184032/graphene-and-pbs-quantum-dots-hybrids-vertical-phototransistor
#17
Xiaoxian Song, Yating Zhang, Haiting Zhang, Yu Yu, Mingxuan Cao, Yongli Che, Hai Tao Dai, Junbo Yang, Xin Ding, Jianquan Yao
Field effect photo transistor (FEpT) based on graphene and lead sulfide quantum dots (PbS QDs) hybrids (PbS QDs embedded in graphene matrix) has been fabricated with vertical architecture through solution process. The n-type Si/SiO2 substrate (gate), Au/Ag nanowires source transparent electrode, active layer and Au drain electrode are vertically stacked in the device. The channel length determined by the thickness of the active layers is downscaled to 250 nm. Photo induced carriers in PbS QDs transfer to graphene due to the high mobility of graphene, and then shift to the drain in an ultra-short transfer time ( ps scale)...
February 10, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28181478/core-shell-formation-in-self-induced-inaln-nanorods
#18
J Palisaitis, C-L Hsiao, L Hultman, J Birch, P O Å Persson
We have examined the early stages of self-induced InAlN core-shell nanorod (NR) formation processes on amorphous carbon substrates in plan-view geometry by means of transmission electron microscopy methods. The results show that the grown structure phase separates during the initial moments of deposition into a majority of Al-rich InAlN and a minority of In-enriched InAlN islands. The islands possess polygonal shapes and are mainly oriented along a crystallographic c-axis. The growth proceeds with densification and coalescence of the In-enriched islands, resulting in a base for the In-enriched NR cores with shape transformation to hexagonal...
February 9, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28177298/high-aspect-ratio-silicon-nanowires-control-fibroblast-adhesion-and-cytoskeleton-organization
#19
Laura Andolfi, Anna Murello, Damiano Cassese, Jelena Ban, Simone Dal Zilio, Marco Lazzarino
The cell-cell and cell-matrix interactions are essential to the survival and proliferation of most cells, and are responsible of triggering a wide range of biochemical pathways. More recently, also the biomechanical role of those interactions was highlighted, showing, for instance that adhesion forces are essential for the cytoskeleton organization. Silicon-nanowires (Si-NWs) with their small size, high aspect ratio and anisotropic mechanical response represent a useful model to investigate the forces involved in the adhesion processes and their role in the cellular development...
February 8, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28177297/enhanced-performance-of-zno-microballoon-arrays-for-triboelectric-nanogenerator
#20
Weili Deng, Binbin Zhang, Long Jin, Yueqi Chen, Wenjun Chu, Haitao Zhang, Minhao Zhu, Weiqing Yang
In recent years, triboelectric nanogenerator (TENG), harvesting energy from the environment as sustainable power source as a kind of new technology, has attracted great attention. Presently, many reports focused on the effect of the surface modification on the performance of electrical output of TENG. In this work, we have fabricated a vertically-grown ZnO microballoon (ZnOMB) arrays on top of pyramid-featured PDMS patterned film, contacted with the PTFE film to construct TENG. The electrical output performances of the designed TENG were presented under the external forces with different frequencies...
February 8, 2017: Nanotechnology
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