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Stephan Benke, Daniel Nettels, Hagen Hofmann, Benjamin Schuler
Single-molecule fluorescence spectroscopy is a powerful approach for probing biomolecular structure and dynamics, including protein folding. For the investigation of nonequilibrium kinetics, F��rster resonance energy transfer (FRET) in combination with confocal multiparameter detection has proven particularly versatile, owing to the large number of observables and the broad range of accessible timescales, especially in combination with rapid microfluidic mixing. However, a comprehensive kinetic analysis of the resulting time series of transfer efficiency histograms and complementary observables can be challenging owing to the complexity of the data...
January 19, 2017: Nanotechnology
Xin Luo, Chi Fang, Caihua Wan, Jialin Cai, Yong Liu, Xiufeng Han, Zhihong Lu, Rui Xiong, Zhongming Zeng
This article reports the characterization of WTe<sub>2</sub> ultrathin flakes devices with characterization of magnetoresistance and Hall resistivity. We found that ultrathin flakes of WTe<sub>2</sub> do not exhibit magnetoresistance saturation when subject to high fields, in a manner similar to their bulk characteristic. The linearity of Hall resistivity in our devices could confirm the compensation of electrons and holes. By relating experimental results to a classic two-band model, we demonstrate that the lower magnetoresistance values may be caused by decreased carrier mobility in our samples...
January 19, 2017: Nanotechnology
Zhuo Xiong, Tongbo Wei, Yonghui Zhang, Xiang Zhang, Chao Yang, Zhiqiang Liu, Guodong Yuan, Jinmin Li, Junxi Wang
Gallium nitride-based nanopyramid light-emitting diodes are a promising technology to achieve highly efficient solid-state lighting and beyond. Here, periodic nanopyramid light-emitting diode arrays on gallium nitride/sapphire templates were fabricated by selective-area metalorganic chemical vapor deposition and multiple-exposure colloidal lithography. The electric field intensity distribution of incident light going through polystyrene microspheres and photoresist are simulated using finite-different time-domain method...
January 19, 2017: Nanotechnology
Kyungtaek Min, Muhammad Umar, Shinyoung Ryu, Soonil Lee, Sunghwan Kim
Ultra-thin and ultra-smooth gold (Au) films are appealing for photonic applications including surface plasmon resonances and transparent contacts. However, poor adhesion at the Au���dielectric interface prohibits the formation of a mechanically stable, ultra-thin, and ultra-smooth Au film. A conventional solution is to use a metallic adhesion layer, such as titanium and chromium however, such layers cause the optical properties of pure Au to deteriorate. Here we report the use of silk protein to enhance the adhesion at the Au���dielectric interfaces, thus obtaining ultra-smooth sub-10 nm Au films...
January 19, 2017: Nanotechnology
Liqian Qi, Di-Ya Pan, Jun-Qing Li, Lihu Liu, Huiyuan Sun
New materials for achieving direct electric field control of ferromagnetism and resistance behavior are highly desirable in the development of multifunctional data storage devices. In this paper, HfO2 nanoporous films have been fabricated on porous anodic alumina (PAA) substrates by DC-reactive magnetron sputtering. Electrically induced resistive switching (RS) and modulated room temperature ferromagnetism are simultaneously found in a Ag/HfO2/PAA/Al (Ag/HP/Al) heterostructure. The switching mechanism between low resistance state (LRS) and high resistance state (HRS) is generally attributed to the formation/rupture of conductive filaments which may consist of oxygen vacancies...
January 19, 2017: Nanotechnology
A Altaweel, A Imam, J Ghanbaja, D Mangin, P Miska, T Gries, T Belmonte
The synthesis of ultrathin, single-crystalline zinc oxide nanowires was achieved by treating in a flowing microwave plasma oxidation process, zinc films coated beforehand by a sputtered thin buffer layer of copper. The aspect ratio of the nanowires can be controlled by the following experimental parameters: treatment duration, furnace temperature, oxygen concentration. An average diameter of 6 nm correlated with a mean length of 750 nm can be reached with a fairly high surface number density for very short treatments, typically less than 1 min...
January 19, 2017: Nanotechnology
Mei-Hwa Lee, Arti Ahluwalia, Jian-Zhou Chen, Neng-Lang Shih, Hung-Yin Lin
Molecularly imprinted polymer nanoparticles incorporating magnetic nanoparticles (MNPs) have been investigated for their selective adsorption properties. Here we describe the synthesis and characterization of magnetic cytosine-imprinted chitosan nanoparticles (CIPs) for gene delivery. In particular, CIPs carrying the mammalian expression plasmid of enhanced green fluorescent protein were prepared by the co-precipitation of MNPs, chitosan and a template nucleobase (cytosine). The results show that the selective reabsorption of cytosine to magnetic CIPs was at least double that of non-imprinted polymers and other nucleobases (such as adenine and thymine)...
January 19, 2017: Nanotechnology
Tong Zhang, Huijuan Yue, Hailong Qiu, Wei Yingjin, Chunzhong Wang, Gang Chen, Zhang Dong
Porous ZnMn2O4 microspheres were prepared via a facile co-precipitation method followed by calcination at various temperatures and evaluated as anode materials for Lithium ion batteries. The sample prepared at 600��C outperformed the other samples in terms of electrochemical performance with high reversible capacity, high-rate capability, and excellent cycling performance. The capacity of the sample remained as high as 999 mAh g-1 at a current rate of 100 mA g-1 after 50 cycles ��� one of the best ever reported for ZnMn2O4-based materials...
January 18, 2017: Nanotechnology
Bharati Gupta, Carlo Mariani, Josh Lipton-Duffin, Nunzio Motta, Pierluigi Mondelli, Maria Betti
Etching with atomic hydrogen as a preparation step before the high-temperature growth process of graphene onto a thin 3C-SiC film grown on Si(111) greatly improves the structural quality of topmost graphene layers. Pit formation and island coalescence, which are typical of graphene growth by SiC graphitization, are quenched and accompanied by widening of the graphene domain sizes to hundreds of nm, and by a significant reduction in surface roughness down to a single substrate bilayer. The surface reconstructions expected for graphene and the underlying layer are shown with atomic resolution by scanning tunnelling microscopy (STM)...
January 18, 2017: Nanotechnology
Xue Zhang, James Joy, Chenwei Zhao, Jin-Ho Kim, Gustavo Fernandes, Jimmy Xu, James Valles
Anodic aluminum oxide (AAO) substrates with a self-ordered triangular array of nanopores provide the means to fabricate multiple forms of nano materials, such as nanowires and nanoparticles. This study focuses on nanostructures that emerge in thin films of metals thermally evaporated onto the surface of AAO. Previous work showed that films of different evaporated metals assume dramatically different structures, e.g. an ordered triangular array of nearly monodisperse nanoparticles forms for Lead(Pb) while a polycrystalline nanohoneycomb structure forms for Silver(Ag)...
January 17, 2017: Nanotechnology
Jiuyi Zhu, Hui Wang, Jiangwen Liu, Liuzhang Ouyang, Min Zhu
Efficient preparation of two-dimensional materials is still a great challenge although they possess unique electrical, optical, and thermal properties. In this study, few-layer MoS2 nanosheets and nanoflakes were exfoliated by the hydrolysis reaction of LiBH4. First, the layered MoS2 powder materials were mixed with LiBH4 to obtain homogenous powder mixture, and then the mixture was heated above the melting point of LiBH4 under 300 ��C and 4 MPa H2 for 2h, during which the layered materials were curled by liquid LiBH4...
January 13, 2017: Nanotechnology
Ryan Wagner, Jason Killgore
A methodology is developed to reconstruct the force applied to an atomic force microscopy (AFM) cantilever given the shape in which it vibrates. This is accomplished by rewriting Bernoulli Euler beam theory such that the force on the cantilever is approximated as a linear superposition of the theoretical cantilever eigenmodes. The weighting factors in this summation are calculated from the amplitude and phase measured along the length of the cantilever. The accuracy of the force reconstruction is shown to depend on the frequency at which the measurement is performed, the number of discrete points measured along the length of the cantilever, and the signal-to-noise ratio of the measured signal...
January 13, 2017: Nanotechnology
Wei Zhan, Cecilie Granerød, Vishnukanthan Venkatachalapathy, Klaus Magnus Johansen, Ingvild Jensen, Andrej Kuznetsov, Øystein Prytz
Using monochromated Electron Energy Loss Spectroscopy (EELS) in a probe-corrected Scanning Transmission Electron Microscope (STEM) we demonstrate band gap mapping in ZnO/ZnCdO thin films with a spatial resolution below 10 nm and spectral precision of 20 meV.
January 13, 2017: Nanotechnology
Inderjeet Singh, Katharina Landfester, Rafael Muñoz-Espí, Amreesh Chandra
The paper discusses a successful strategy for tuning the hollow, porous or even solid morphologies of pure and Cu(2+)-doped CeO2 nanostructures. The reaction of nanodroplets at the interface in miniemulsions is significantly affected by the concentration of dopants. The growth mechanism is both reaction- as well as diffusion-controlled, which finally determines the particular morphology. With a varying degree of dopant concentration and quantum confinement, the concentration of Ce(3+) available on the surface of the nano-droplets and -particles is found to change quite appreciably...
January 13, 2017: Nanotechnology
Irina V Antonova, Irina I Kurkina, Nadezhda A Nebogatikova, Alexander I Komonov, Svetlana A Smagulova
The band structure and electric properties of films created from a partially fluorinated graphene suspension are analyzed in this paper. As may be inferred from the structural study, graphene islands (quantum dots) are formed in these films. Various types of negative differential resistance (NDR) and a step-like increase in the current are found for films created from the fluorinated graphene suspension. NDR resulting from the formation of the potential barrier system in the film and corresponding to the theoretical prediction is observed for a relatively low fluorination degree...
January 13, 2017: Nanotechnology
Munu Borah, Abhishek K Pathak, Dilip K Singh, Prabir Pal, Sanjay R Dhakate
A method for defect-free large crystallite graphene growth remains unknown despite much research effort. In this work, we discuss the role of flow duration of H2 gas for the production of graphene as per requirement and production at a minimum flow rate considering the safety issue of hydrogen utilization. The copper substrate used for growth was treated for different time intervals (0 to 35 min) in H2 flow prior to growth. Structural and chemical changes occurring in the copper substrate surface were probed by grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy...
January 13, 2017: Nanotechnology
Xuankai Huang, Haiyan Zhang, Na Li
Transition metal oxides with high specific capacitance materials are ideal for a new generation of high-performance transparent supercapacitors but are rarely reported. Commonly, the synthesis of the required nanostructured materials is a crucial step required to achieve the transparency of the device. In this study, a Fe2O3 nanowire network transparent film is developed simply through air-solution interface reactions and wrapped in graphene shells for use as transparent electrodes. The Fe2O3 nanowire networks surrounded by the graphene layer exhibit an effective encapsulation structure, providing rapid three-dimensional electron and ion transport pathways...
January 13, 2017: Nanotechnology
Danish Ali, Bin Yu, Xiaochao Duan, Hao Yu, Meifang Zhu
In the modern era, the invention of new energy sources is important in order to make advances possible in electronic media. A triboelectric nanogenerator (TENG) is considered to be strong design that converts mechanical power into electrical power, using organic (polymer) or inorganic (lead, ceramic etc) materials to initiate the triboelectrification process, followed by charge separation. In this study, a lead-free BaTiO3/PDMS-Al-based TENG was fabricated by mixing tetragonal ferroelectric BaTiO3 nanocrystals in a PDMS matrix to make a composite for a working electrode film...
January 13, 2017: Nanotechnology
Shantanu Das, Jeff Drucker
The nucleation density and average size of graphene crystallites grown using cold wall chemical vapor deposition (CVD) on 4��m-thick Cu films electrodeposited on W substrates can be tuned by varying growth parameters. Growth at a fixed substrate temperature of 1000��C and total pressure of 700 Torr using Ar, H2 and CH4 mixtures enabled the contribution of total flow rate, CH4:H2 ratio and dilution of the CH4/H2 mixture by Ar to be identified. The largest variation in nucleation density was obtained by varying the CH4:H2 ratio...
January 13, 2017: Nanotechnology
Shinya Kano, Minoru Fujii
We study a conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage. Heat leakage current from a hot electrode to a cold electrode is taken into account in the analysis of the harvester operation. Modeling of electrical output indicates that a maximum heat leakage current is not negligible because it is larger than that of heat current harvested into electrical power. Reduction of heat leakage is required in this energy harvester in order to obtain efficient heat-to-electrical conversion...
January 13, 2017: Nanotechnology
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