bluuebunny/crossref_metadata_2025 huggingface dataset:
Reusable ionic liquid-catalyzed oxidative coupling of azoles and benzylic compounds via sp3C–N bond formation under metal-free conditions
Authors: Liu Wenbo , Liu Chenjiang , Zhang Yonghong , Sun Yadong , Abdukadera Ablimit , Wang Bin , Li He , Ma Xuecheng , Zhang Zengpeng
Published: June 2015

The heterocyclic ionic liquid-catalyzed direct oxidative amination of benzylic sp3C–H bondsviaintermolecular sp3C–N bond formation for the synthesis ofN-alkylated azoles under metal-free conditions is reported for the first time.
A modified De-Gennes's trumpet model for the prediction of practical adhesion of dynamically- and structurally heterogeneous polymeric networks on solid surfaces
Authors: Yazdani-Ahmadabadi Hossein , Rastegar Saeed , Ranjbar Zahra
Published: June 2015

A theoretical model for the prediction of practical adhesion of dynamically- and structurally heterogeneous polymeric networks on solid surfaces.
Thermal decomposition mechanism of Co–ANPyO/CNTs nanocomposites and their application to the thermal decomposition of ammonium perchlorate
Authors: Cheng Jian , Zhang Rongxian , Liu Zuliang , Li Lixia , Zhao Fengqi , Xu Siyu
Published: June 2015

This research reported the preparation, characterization, thermal decomposition mechanism and catalytic performance of Co–ANPyO/CNTs nanocomposites.
Design, synthesis and biological evaluation of esculetin derivatives as anti-tumour agents
Authors: Wang Ping , Xia Yang-Liu , Yu Yang , Lu Jun-Xia , Zou Li-Wei , Feng Lei , Ge Guang-Bo , Yang Ling
Published: June 2015

Introduction of a nitrogen containing group as hydrogen bond acceptor is a useful strategy for the structure modification.
Tetrazole-based infinite coordination polymer for encapsulation of TiO2 and its potential application for fabrication of ZnO@TiO2 core–shell structures
Authors: Abedi Sedigheh , Morsali Ali
Published: June 2015

A new and facile technique for the preparation of ZnO@TiO2 core–shell nano/micro sphere structures from tetrazolate ligand, (1,3-bis(tetrazol-5-ylmethyl)benzene (btb)), was addressed.
Tandem catalytic conversion of glycerol using solid catalysts followed by transesterification to produce alkyl lactate
Authors: Ren Shoujie , Ye X. Philip , Ayers Paul D.
Published: June 2015

An environmentally benign process for alkyl lactate production from glycerol using solid catalysts with alcohols and carbon dioxide.
Corrole–BODIPY conjugates: enhancing the fluorescence and phosphorescence of the corrole complex via efficient through bond energy transfer
Authors: Chen Wei , Zhang Jianfeng , Mack John , Kubheka Gugu , Nyokong Tebello , Shen Zhen
Published: June 2015

Excitation of a BODIPY chromophore increases the luminescence intensity of an iridium(iii) corrole–BODIPY conjugate, due to efficient through-bond energy transfer.
Red up-conversion emission in α-KYb3F10:Er3+films made by electrodeposition
Authors: Wu Xiaowen , Tian Linlin , Lu Qinyan , Liu Run
Published: June 2015

Annealed α-KYb3F10:Er3+(2 mol%) films grown through electrodeposition from aqueous solutions at low temperature show nearly single intense red emission excited by a 980 nm laser.
PEG-assisted two-component approach for the facile synthesis of 5-aryl-1,2,4-triazolidine-3-thiones under catalyst-free conditions
Authors: Ramesh Rathinam , Lalitha Appaswami
Published: June 2015

A straightforward and greener PEG-assisted protocol has been disclosed for the synthesis of 5-aryl-1,2,4-triazolidine-3-thiones via the reaction of aromatic aldehydes and thiosemicarbazides using very convenient neutral reaction conditions.
Carbon microspheres air electrode for rechargeable Li–O2 batteries
Authors: Meng Wei , Liu Shengwei , Wen Lina , Qin Xue
Published: June 2015

Carbon microspheres (CMs) were synthesized by a reflux-calcination method and showed a large BET surface area of 626.919 m2 g−1, a typical micropore structure and good electrochemical properties.
Melt processing and characterisation of polyamide 6/graphene nanoplatelet composites
Authors: Mayoral B. , Harkin-Jones E. , Khanam P. Noorunnisa , AlMaadeed M. A. , Ouederni M. , Hamilton A. R. , Sun D.
Published: June 2015

The incorporation of graphene nanoplatelets into nylon (PA6)viamelt processing on an industrial scale significantly increases the crystallinity, stiffness, and electrical conductivity of the resulting composites.
A simple method for the fabrication of nanomotors based on a gold nanosheet decorated with CoPt nanoparticles
Authors: Amouzadeh Tabrizi Mahmoud , Shamsipur Mojtaba
Published: June 2015

In this communication we present an extremely rapid, simple and template-free method for the electrochemical fabrication of CoPt/gold nanosheet motors (NSMs) via a three-step applied potential process.
Conductive, flexible transparent electrodes based on mechanically rubbed nonconductive polymer containing silver nanowires
Authors: Jeong Soon Moon , Kim Jung-Hye , Song Seongkyu , Seo Jungpil , Hong Jung-Il , Ha Na Young , Takezoe Hideo , Jeong Jaewook , Kim Hyunmin
Published: June 2015

This paper explores the use of rubbing for alleviating the problem of lost electrical conductivity, which is typically caused by the use of nonconductive polymers to improve the substrate adhesion and surface roughness of metal nanowire networks.
A facile hydrothermal method to synthesize Sb2S3/Sb4O5Cl2 composites with three-dimensional spherical structures
Authors: Jiang Qian , Yuan Xingzhong , Wang Hou , Chen Xiaohong , Gu Shansi , Liu Yang , Wu Zhibin , Zeng Guangming
Published: June 2015

Three-dimensional spherical Sb2S3/Sb4O5Cl2 microcrystallines were synthesized for the first time via a facile hydrothermal process without any oxychlorides at 100 °C.
DTX-loaded star-shaped TAPP-PLA-b-TPGS nanoparticles for cancer chemical and photodynamic combination therapy
Authors: Wang Teng , Zhu Dunwan , Liu Gan , Tao Wei , Cao Wei , Zhang Linhua , Wang Lijun , Chen Hongbo , Mei Lin , Huang Laiqiang , Zeng Xiaowei
Published: June 2015

A novel star-shaped copolymer TAPP-PLA-b-TPGS was synthesized as drug nanocarriers for cancer chemical and photodynamic combination therapy.
Highly stable tribological performance and hydrophobicity of porous polyimide material filled with lubricants in a simulated space environment
Authors: Lv Mei , Wang Chao , Wang Qihua , Wang Tingmei , Liang Yongmin
Published: June 2015

Highly stable tribological and hydrophobic performance of porous polyimide material filled with lubricants in a rigorous space environment.
Highly enantioselective construction of tertiary thioethers and alcohols via phosphine-catalyzed asymmetric γ-addition reactions of 5H-thiazol-4-ones and 5H-oxazol-4-ones: scope and mechanistic understandings
Authors: Wang Tianli , Yu Zhaoyuan , Hoon Ding Long , Huang Kuo-Wei , Lan Yu , Lu Yixin
Published: June 2015

A new method for facile access to enantioenriched tertiary thioethers/alcohols.
Synthesis of triazolium-based mono- and tris-branched [1]rotaxanes using a molecular transporter of dibenzo-24-crown-8
Authors: Waelès P. , Clavel C. , Fournel-Marotte K. , Coutrot F.
Published: June 2015

A general synthesis to mono- and multi-branched [1]rotaxanes that are devoid of any efficient template is reported.
A mechanically bendable superhydrophobic steel surface with self-cleaning and corrosion-resistant properties
Authors: Latthe Sanjay S. , Sudhagar P. , Devadoss Anitha , Kumar A. Madhan , Liu Shanhu , Terashima Chiaki , Nakata Kazuya , Fujishima Akira
Published: June 2015

We present an effective way to develop superhydrophobic steel surface which shows stable superhydrophobicity under harsh mechanical bending.
Hierarchical NiCo2O4@NiMoO4 core–shell hybrid nanowire/nanosheet arrays for high-performance pseudocapacitors
Authors: Cheng Ding , Yang Yefeng , Xie Jinlei , Fang Changjiang , Zhang Guoqing , Xiong Jie
Published: June 2015

Hierarchical NiCo2O4@NiMoO4 core–shell nanowire/nanosheet arrays were successfully fabricated and assembled in an asymmetric supercapacitor device with outstanding electrochemical performance.
p,p′-Dichlorodiphenyltrichloroethane inhibits the apoptosis of colorectal adenocarcinoma DLD1 cells through PI3K/AKT and Hedgehog/Gli1 signaling pathways
Authors: Song Li , Zhao Meirong , Liu Jianxin , Li Zhuoyu , Xiao Hong , Liu Weiping
Published: June 2015

p,p′-Dichlorodiphenyltrichloroethane is able to inhibit the apoptosis of human colorectal adenocarcinoma cells, which may be an important mechanism to contribute to colorectal cancer development.
Small dim object tracking using a multi objective particle swarm optimisation technique
Authors: Ahmadi Kaveh , Salari Ezzatollah
Published: June 2015

Dim object tracking in a heavy clutter environment is a theoretical and technological challenge in the field of image processing. For a small dim object, conventional tracking methods fail for the lack of geometrical information. Multiple hypotheses testing (MHT) is one of the generally accepted methods in target tracking systems. However, processing a tree structure with a significant number of branches in MHT has been a challenging issue. Tracking high‐speed objects with traditional MHT requires some presumptions which limit the capabilities of these methods. This study presents a hierarchal tracking system in two levels to solve this problem. For each point in the lower‐level, a multi objective particle swarm optimisation technique is applied to a group of consecutive frames to reduce the number of branches in each tracking tree. Thus, an optimum track for each moving object is obtained in a group of frames. In the upper‐level, an iterative process is used to connect the matching optimum tracks of the consecutive frames based on the spatial information and fitness values. The experimental results show that the proposed method has a superior performance in relation to some common dim object tracking methods over different image sequence data sets.
Formation of methane nano-bubbles during hydrate decomposition and their effect on hydrate growth
Authors: Bagherzadeh S. Alireza , Alavi Saman , Ripmeester John , Englezos Peter
Published: June 2015

Molecular dynamic simulations are performed to study the conditions for methane nano-bubble formation during methane hydrate dissociation in the presence of water and a methane gas reservoir. Hydrate dissociation leads to the quick release of methane into the liquid phase which can cause methane supersaturation. If the diffusion of methane molecules out of the liquid phase is not fast enough, the methane molecules agglomerate and form bubbles. Under the conditions of our simulations, the methane-rich quasi-spherical bubbles grow to become cylindrical with a radius of ∼11 Å. The nano-bubbles remain stable for about 35 ns until they are gradually and homogeneously dispersed in the liquid phase and finally enter the gas phase reservoirs initially set up in the simulation box. We determined that the minimum mole fraction for the dissolved methane in water to form nano-bubbles is 0.044, corresponding to about 30% of hydrate phase composition (0.148). The importance of nano-bubble formation to the mechanism of methane hydrate formation, growth, and dissociation is discussed.
Self-excited coupled-microcantilevers for mass sensing
Authors: Endo Daichi , Yabuno Hiroshi , Higashino Keiichi , Yamamoto Yasuyuki , Matsumoto Sohei
Published: June 2015

This paper reports ultrasensitive mass detection based on the relative change in the amplitude ratio of the first mode oscillation using self-excited coupled microcantilevers. The method proposed and demonstrated using the macrocantilevers in the previous study can measure eigenstate shifts caused by objects with high accuracy without being affected by the viscous damping effect of measurement environments. In this study, moving towards the use of this method for small mass measurements, we established the self-excited coupled microcantilevers and we have achieved in measurements of very small mass (about 1 ng) with 1% order of error.
Self-assembled ultralight three-dimensional polypyrrole aerogel for effective electromagnetic absorption
Authors: Xie Aming , Wu Fan , Sun Mengxiao , Dai Xiaoqing , Xu Zhuanghu , Qiu Yanyu , Wang Yuan , Wang Mingyang
Published: June 2015

A facile self-assembled polymerization method has been used to form pyrrole to an ultralight three-dimensional (3D) polypyrrole (PPy) aerogel. It exhibits an effective electromagnetic absorption (EA) bandwidth (deeper than −10 dB), which was characterized as 6.2 GHz when the filler loading is only 7 wt. % in paraffin based composite. This 3D-PPy aerogel can be considered as a light weight, low adjunction, thin thickness, and high performance EA material.
Dissociative electron attachment to the gas-phase nucleobase hypoxanthine
Authors: Dawley M. Michele , Tanzer Katrin , Carmichael Ian , Denifl Stephan , Ptasińska Sylwia
Published: June 2015

We present high-resolution measurements of the dissociative electron attachment (DEA) to isolated gas-phase hypoxanthine (C5H4N4O, Hyp), a tRNA purine base. The anion mass spectra and individual ion efficiency curves from Hyp were measured as a function of electron energy below 9 eV. The mass spectra at 1 and 6 eV exhibit the highest anion yields, indicating possible common precursor ions that decay into the detectable anionic fragments. The (Hyp − H) anion (C5H3N4O−) exhibits a sharp resonant peak at 1 eV, which we tentatively assign to a dipole-bound state of the keto-N1H,N9H tautomer in which dehydrogenation occurs at either the N1 or N9 position based upon our quantum chemical computations (B3LYP/6-311+G(d,p) and U(MP2-aug-cc-pVDZ+)) and prior studies with adenine. This closed-shell dehydrogenated anion is the dominant fragment formed upon electron attachment, as with other nucleobases. Seven other anions were also observed including (Hyp − NH)−, C4H3N4−/C4HN3O−, C4H2N3−, C3NO−/HC(HCN)CN−, OCN−, CN−, and O−. Most of these anions exhibit broad but weak resonances between 4 and 8 eV similar to many analogous anions from adenine. The DEA to Hyp involves significant fragmentation, which is relevant to understanding radiation damage of biomolecules.
Induce magnetism into silicene by embedding transition-metal atoms
Authors: Sun Xiaotian , Wang Lu , Lin Haiping , Hou Tingjun , Li Youyong
Published: June 2015

Embedding transition-metal (TM) atoms into nonmagnetic nanomaterials is an efficient way to induce magnetism. Using first-principles calculations, we systematically investigated the structural stability and magnetic properties of TM atoms from Sc to Zn embedded into silicene with single vacancy (SV) and double vacancies (DV). The binding energies for different TM atoms correlate with the TM d-shell electrons. Sc, Ti, and Co show the largest binding energies of as high as 6 eV, while Zn has the lowest binding energy of about 2 eV. The magnetic moment of silicene can be modulated by embedding TM atoms from V to Co, which mainly comes from the 3d orbitals of TM along with partly contributions from the neighboring Si atoms. Fe atom on SV and Mn atom on DV have the largest magnetic moment of more than 3 μB. In addition, we find that doping of N or C atoms on the vacancy site could greatly enhance the magnetism of the systems. Our results provide a promising approach to design silicene-based nanoelectronics and spintronics device.
Brownian motion of a particle with arbitrary shape
Authors: Cichocki Bogdan , Ekiel-Jeżewska Maria L. , Wajnryb Eligiusz
Published: June 2015

Brownian motion of a particle with an arbitrary shape is investigated theoretically. Analytical expressions for the time-dependent cross-correlations of the Brownian translational and rotational displacements are derived from the Smoluchowski equation. The role of the particle mobility center is determined and discussed.
Effects of work function on thermal sensitivity of electrode potential
Authors: Lim Hyuck , Shi Yang , Wang Meng , Qiao Yu
Published: June 2015

In recently developed thermally chargeable supercapacitors, temperature dependent capacitive effect is employed to harvest and store low-grade heat as electric energy, for which a key factor dominating the system performance is the thermal sensitivity of electrode potential (dV/dT). In the current study, the influence of electrode material properties, particularly the work function, is analyzed through a set of thermal-to-electric energy conversion experiments. The testing data suggest that dV/dT increases monotonously with the work function. This finding sheds light on electrode materials selection.
Modeling of anisotropic two-dimensional materials monolayer HfS2 and phosphorene metal-oxide semiconductor field effect transistors
Authors: Chang Jiwon
Published: June 2015

Ballistic transport characteristics of metal-oxide semiconductor field effect transistors (MOSFETs) based on anisotropic two-dimensional materials monolayer HfS2 and phosphorene are explored through quantum transport simulations. We focus on the effects of the channel crystal orientation and the channel length scaling on device performances. Especially, the role of degenerate conduction band (CB) valleys in monolayer HfS2 is comprehensively analyzed. Benchmarking monolayer HfS2 with phosphorene MOSFETs, we predict that the effect of channel orientation on device performances is much weaker in monolayer HfS2 than in phosphorene due to the degenerate CB valleys of monolayer HfS2. Our simulations also reveal that at 10 nm channel length scale, phosphorene MOSFETs outperform monolayer HfS2 MOSFETs in terms of the on-state current. However, it is observed that monolayer HfS2 MOSFETs may offer comparable, but a little bit degraded, device performances as compared with phosphorene MOSFETs at 5 nm channel length.
The role of pyrimidine and water as underlying molecular constituents for describing radiation damage in living tissue: A comparative study
Authors: Fuss M. C. , Ellis-Gibbings L. , Jones D. B. , Brunger M. J. , Blanco F. , Muñoz A. , Limão-Vieira P. , García G.
Published: June 2015

Water is often used as the medium for characterizing the effects of radiation on living tissue. However, in this study, charged-particle track simulations are employed to quantify the induced physicochemical and potential biological implications when a primary ionising particle with energy 10 keV strikes a medium made up entirely of water or pyrimidine. Note that pyrimidine was chosen as the DNA/RNA bases cytosine, thymine, and uracil can be considered pyrimidine derivatives. This study aims to assess the influence of the choice of medium on the charged-particle transport, and identify how appropriate it is to use water as the default medium to describe the effects of ionising radiation on living tissue. Based on the respective electron interaction cross sections, we provide a model, which allows the study of radiation effects not only in terms of energy deposition (absorbed dose and stopping power) but also in terms of the number of induced molecular processes. Results of these parameters for water and pyrimidine are presented and compared.
Investigation of the pressure dependent thermodynamic and elastic properties of 1,3,5-triamino-2,4,6-trinitrobenzene using dispersion corrected density functional theory
Authors: Rykounov A. A.
Published: June 2015

The influence of pressure on the thermodynamic, structural, and elastic properties of the 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) molecular crystal at T = 0 is systematically studied. Calculations are carried out using density functional theory methods in a plane wave basis set with dispersion corrections for the exchange-correlation part of total energy, and ultrasoft pseudopotentials. The equilibrium unit cell parameters, the cold compression curve in the pressure range of 0–50 GPa and the sound speeds are computed. The effect of finite pressure on the molecular structure of TATB is elucidated from the analysis of relative changes in the intra- and intermolecular geometrical parameters. For the first time, the full set of elastic constants of this crystal at zero and non-zero pressures is determined from ab initio calculations. The resulted structural, elastic, and acoustic properties of TATB are shown to be in a good agreement with available experimental and theoretical data.
Three dimensional finite element modeling and characterization of intermediate states in single active layer phase change memory devices
Authors: Cinar I. , Aslan B. , Gokce A. , Dincer O. , Karakas V. , Stipe B. , Katine J. A. , Aktas G. , Ozatay O.
Published: June 2015

The high contrast in the electrical resistivity between amorphous and crystalline states of a phase change material can potentially enable multiple memory levels for efficient use of a data storage medium. We report on our investigation of the role of the current injection site geometry (circular and square) in stabilizing such intermediate states within a nanoscale single-phase change material system (Ge2Sb2Te5). We have developed a three dimensional multiphysics model, which includes phase change kinetics, electrical, thermal, thermoelectric, and percolation effects, all as a function of temperature, using an iterative approach with coupled differential equations. Our model suggests that the physical origin of the formation of stable intermediate states in square top contact devices is mainly due to anisotropic heating during the application of a programming current pulse. Furthermore, the threshold current requirement and the width of the programming window are determined by crystallite nucleation and growth rates such that a higher crystallization rate leads to a narrower range of current pulses for switching to intermediate resistance level(s). The experimentally determined resistance maps, those that are indicative of the crystallinity, show good agreement with the simulated phase change behavior confirming the existence of stable intermediate states. Our model successfully predicts the required programming conditions for such mixed-phase levels, which can be used to optimize memory cells for future ultra-high density data storage applications.
Analyzing degradation effects of organic light-emitting diodes via transient optical and electrical measurements
Authors: Schmidt Tobias D. , Jäger Lars , Noguchi Yutaka , Ishii Hisao , Brütting Wolfgang
Published: June 2015

Although the long-term stability of organic light-emitting diodes (OLEDs) under electrical operation made significant progress in recent years, the fundamental underlying mechanisms of the efficiency decrease during operation are not well understood. Hence, we present a comprehensive degradation study of an OLED structure comprising the well-known green phosphorescent emitter Ir(ppy)3. We use transient methods to analyze both electrical and optical changes during an accelerated aging protocol. Combining the results of displacement current measurements with time-resolved investigation of the excited states lifetimes of the emitter allows for a correlation of electrical (e.g., increase of the driving voltage due to trap formation) and optical (e.g., decrease of light-output) changes induced by degradation. Therewith, it is possible to identify two mechanisms resulting in the drop of the luminance: a decrease of the radiative quantum efficiency of the emitting system due to triplet-polaron-quenching at trapped charge carriers and a modified charge carrier injection and transport, as well as trap-assisted non-radiative recombination resulting in a deterioration of the charge carrier balance of the device.
Optical and structural properties of sulfur-doped ELOG InP on Si
Authors: Sun Yan-Ting , Junesand Carl , Metaferia Wondwosen , Kataria Himanshu , Julian Nick , Bowers John , Pozina Galia , Hultman Lars , Lourdudoss Sebastian
Published: June 2015

Optical and structural properties of sulfur-doped epitaxial lateral overgrowth (ELOG) InP grown from nano-sized openings on Si are studied by room-temperature cathodoluminescence and cross-sectional transmission electron microscopy (XTEM). The dependence of luminescence intensity on opening orientation and dimension is reported. Impurity enhanced luminescence can be affected by the facet planes bounding the ELOG layer. Dark line defects formed along the [011] direction are identified as the facet planes intersected by the stacking faults in the ELOG layer. XTEM imaging in different diffraction conditions reveals that stacking faults in the seed InP layer can circumvent the SiO2 mask during ELOG and extend to the laterally grown layer over the mask. A model for Suzuki effect enhanced stacking fault propagation over the mask in sulfur-doped ELOG InP is constructed and in-situ thermal annealing process is proposed to eliminate the seeding stacking faults.
A biocompatible microchip and methodology for efficiently trapping and positioning living cells into array based on negative dielectrophoresis
Authors: Guo Xiaoliang , Zhu Rong
Published: June 2015

We present a microchip and trapping methodology based on negative dielectrophoresis (nDEP), whereby living cells were manipulated and positioned into an array with high trapping efficiency while maintaining good viability. The main factors that ensured good viability of cells were investigated including temperature of medium, extra transmembrane potential on cells, and electrolysis effect in DEP-based trapping. Optimum DEP conditions for the microchip were determined by considering both biocompatibility and trapping efficiency. Experiments demonstrated that under a voltage of 3.6–4 Vpp and at a frequency of 100 kHz, HeLa cells could be trapped and positioned into an array in less than 10 s while maintaining good viability. The normal adherence morphology and fluorescence of the cells, dyed with propidium iodide and Calcein-AM, were observed and verified the biocompatibility of the microchip and trapping methodology.
VO2-like thermo-optical switching effect in one-dimensional nonlinear defective photonic crystals
Authors: Zhang Juan , Zhang Rongjun , Wang Yang
Published: June 2015

A new approach to achieve VO2-like thermo-optical switching in a one-dimensional photonic crystal by the combination of thermo-optical and optical Kerr effects was proposed and numerically demonstrated in this study. The switching temperature and the hysteresis width can be tuned in a wide temperature range. Steep transition, high optical contrast, and low pumping power can be achieved at the same time. This kind of one-dimensional photonic crystal-based bistable switch will be low-cost, easy-to-fabricate, and versatile in practical applications compared with traditional VO2-type one.
Evaluation of the electrical contact area in contact-mode scanning probe microscopy
Authors: Celano Umberto , Hantschel Thomas , Giammaria Guido , Chintala Ravi Chandra , Conard Thierry , Bender Hugo , Vandervorst Wilfried
Published: June 2015

The tunneling current through an atomic force microscopy (AFM) tip is used to evaluate the effective electrical contact area, which exists between tip and sample in contact-AFM electrical measurements. A simple procedure for the evaluation of the effective electrical contact area is described using conductive atomic force microscopy (C-AFM) in combination with a thin dielectric. We characterize the electrical contact area for coated metal and doped-diamond tips operated at low force (<200 nN) in contact mode. In both cases, we observe that only a small fraction (<10 nm2) of the physical contact (∼100 nm2) is effectively contributing to the transport phenomena. Assuming this reduced area is confined to the central area of the physical contact, these results explain the sub-10 nm electrical resolution observed in C-AFM measurements.
Crossover of two power laws in the anomalous diffusion of a two lipid membrane
Authors: Bakalis Evangelos , Höfinger Siegfried , Venturini Alessandro , Zerbetto Francesco
Published: June 2015

Molecular dynamics simulations of a bi-layer membrane made by the same number of 1-palmitoyl-2-oleoyl-glycero-3-phospho-ethanolamine and palmitoyl-oleoyl phosphatidylserine lipids reveal sub-diffusional motion, which presents a crossover between two different power laws. Fractional Brownian motion is the stochastic mechanism that governs the motion in both regimes. The location of the crossover point is justified with simple geometrical arguments and is due to the activation of the mechanism of circumrotation of lipids about each other.
Deviation from the Landau-Lifshitz-Gilbert equation in the inertial regime of the magnetization
Authors: Olive E. , Lansac Y. , Meyer M. , Hayoun M. , Wegrowe J.-E.
Published: June 2015

We investigate in details the inertial dynamics of a uniform magnetization in the ferromagnetic resonance context. Analytical predictions and numerical simulations of the complete equations within the Inertial Landau-Lifshitz-Gilbert (ILLG) model are presented. In addition to the usual precession resonance, the inertial model gives a second resonance peak associated to the nutation dynamics provided that the damping is not too large. The analytical resolution of the equations of motion yields both the precession and nutation angular frequencies. They are function of the inertial dynamics characteristic time τ, the dimensionless damping α, and the static magnetic field H. A scaling function with respect to ατγH is found for the nutation angular frequency, also valid for the precession angular frequency when ατγH ≫ 1. Beyond the direct measurement of the nutation resonance peak, we show that the inertial dynamics of the magnetization has measurable effects on both the width and the angular frequency of the precession resonance peak when varying the applied static field. These predictions could be used to experimentally identify the inertial dynamics of the magnetization proposed in the ILLG model.
Electrical field modification of dynamic magnetic properties in FeCo films grown onto [Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32(011) piezoelectric substrates with Ru underlayers
Authors: Phuoc Nguyen N. , Ong C. K.
Published: June 2015

A detailed investigation of electrical tuning of dynamic magnetization of the FeCo magnetic thin film grown onto a PMN-PT piezoelectric substrate was carried out based on the measurement of the zero-field permeability spectra under the application of a voltage across the thickness of the substrate. The resonance frequency can be tuned from 2.95 GHz to 5.9 GHz upon the application of a voltage on the sample in unpoled state. After poling, the resonance frequency of the sample can be tuned in the range from 4.75 GHz to 5.9 GHz. In addition, it was found that after poling the peak of the permeability spectra is broadened compared to before poling, which can be tentatively attributed to the magnetic anisotropy dispersion arising from the presence of the stress-induced anisotropy. The result is also discussed in conjunction with the angular measurement of the static hysteresis loops of the sample before and after poling.
Electrical properties of single CuO nanowires for device fabrication: Diodes and field effect transistors
Authors: Florica Camelia , Costas Andreea , Boni Andra Georgia , Negrea Raluca , Ion Lucian , Preda Nicoleta , Pintilie Lucian , Enculescu Ionut
Published: June 2015

High aspect ratio CuO nanowires are synthesized by a simple and scalable method, thermal oxidation in air. The structural, morphological, optical, and electrical properties of the semiconducting nanowires were studied. Au-Ti/CuO nanowire and Pt/CuO nanowire electrical contacts were investigated. A dominant Schottky mechanism was evidenced in the Au-Ti/CuO nanowire junction and an ohmic behavior was observed for the Pt/CuO nanowire junction. The Pt/CuO nanowire/Pt structure allows the measurements of the intrinsic transport properties of the single CuO nanowires. It was found that an activation mechanism describes the behavior at higher temperatures, while a nearest neighbor hopping transport mechanism is characteristic at low temperatures. This was also confirmed by four-probe resistivity measurements on the single CuO nanowires. By changing the metal/semiconductor interface, devices such as Schottky diodes and field effect transistors based on single CuO p-type nanowire semiconductor channel are obtained. These devices are suitable for being used in various electronic circuits where their size related properties can be exploited.
Mesoscopic harmonic mapping of electromechanical response in a relaxor ferroelectric
Authors: Vasudevan Rama K. , Zhang Shujun , Ding Jilai , Okatan M. Baris , Jesse Stephen , Kalinin Sergei V. , Bassiri-Gharb Nazanin
Published: June 2015

Relaxor-ferroelectrics are renowned for very large electrostrictive response, enabling applications in transducers, actuators, and energy harvesters. However, insight into the dissimilar contributions (polarization rotation, wall motion) to the electromechanical response from electrostrictive strain, and separation of such contributions from linear piezoelectric response are largely ignored at the mesoscale. Here, we employ a band-excitation piezoresponse force microscopy (BE-PFM) technique to explore the first and second harmonics of the piezoelectric response in prototypical relaxor-ferroelectric 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-0.28PT) single crystals. Third order polynomial fitting of the second harmonic reveals considerable correlation between the cubic coefficient map and the first harmonic piezoresponse amplitude. These results are interpreted under a modified Rayleigh framework, as evidence for domain wall contributions to enhanced electromechanical response. These studies highlight the contribution of domain wall motion in the electromechanical response of relaxor ferroelectrics, and further show the utility of harmonic BE-PFM measurements in spatially mapping the mesoscopic variability inherent in disordered systems.
Factors influencing the temporal growth rate of the high order TMn modes in the Ka-band overmoded Cherenkov oscillator
Authors: Wu Dapeng , Shu Ting , Ju Jinchuan
Published: June 2015

When the wavelength of overmoded Cherenkov oscillator goes into Ka-band, power handling capacity becomes an essential issue. Using the TM02 mode or higher order TM0n modes as the operating mode is a potential solution. This paper is aimed to find some proper parameters to make the temporal growth rate of the TM02 mode higher in our previously studied Gigawatt (GW)-class Ka band oscillator. An accurate and fast calculation method of the “hot” dispersion equation is derived for rectangular corrugated SWSs, which are widely used in the high frequency Cherenkov devices. Then, factors that affect the temporal growth rate of the high order TM0n modes are analyzed, including the depth of corrugation, the radius of drift tube, and the diode voltage. Results show that, when parameters are chosen properly, the temporal growth rate of the TM02 mode can be as high as 0.3 ns−1.
Assessment of ion kinetic effects in shock-driven inertial confinement fusion implosions using fusion burn imaging
Authors: Rosenberg M. J. , Séguin F. H. , Amendt P. A. , Atzeni S. , Rinderknecht H. G. , Hoffman N. M. , Zylstra A. B. , Li C. K. , Sio H. , Gatu Johnson M. , Frenje J. A. , Petrasso R. D. , Glebov V. Yu. , Stoeckl C. , Seka W. , Marshall F. J. , Delettrez J. A. , Sangster T. C. , Betti R. , Wilks S. C. , Pino J. , Kagan G. , Molvig K. , Nikroo A.
Published: June 2015

The significance and nature of ion kinetic effects in D3He-filled, shock-driven inertial confinement fusion implosions are assessed through measurements of fusion burn profiles. Over this series of experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number, NK) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially resolved measurements of the fusion burn are used to examine kinetic ion transport effects in greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison of measured and simulated burn profiles shows that models including ion transport effects are able to better match the experimental results. In implosions characterized by large Knudsen numbers (NK ∼ 3), the fusion burn profiles predicted by hydrodynamics simulations that exclude ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that includes a model of ion diffusion is able to qualitatively match the measured profile shapes. Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the observed trends, though further refinement of the models is needed for a more complete and quantitative understanding of ion kinetic effects.
Effect of N2 and Ar gas on DC arc plasma generation and film composition from Ti-Al compound cathodes
Authors: Zhirkov Igor , Oks Efim , Rosen Johanna
Published: June 2015

DC arc plasma from Ti, Al, and Ti1−xAlx (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-state-resolved ion energy for Ar and N2 pressures in the range 10−6 to 3 × 10−2 Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. Introducing N2 above ∼5 × 10−3 Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N2 atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions.
Analysis of diffusion trajectories of anisotropic objects
Authors: Roh Sunghan , Yi Juyeon , Kim Yong Woon
Published: June 2015

We theoretically analyze diffusion trajectories of an anisotropic object moving on a two dimensional space in the absence of an external field. In determining diffusion parameters associated with the shape anisotropy, we devise a measure based on the gyration tensor and obtain its analytic expression exactly. Its efficiency and statistical convergence are examined in comparison with the fourth cumulant of particle displacement. We find that the estimation of diffusion constants based on the gyration measure is more efficient than the analysis adopting the fourth cumulant.
Spin orientation driven static and dynamic magnetic process in amorphous FeCoBSi thin films
Authors: Zhou Peiheng , Luo Xiaojia , Zhang Li , Lu Haipeng , Xie Jianliang , Deng Longjiang
Published: June 2015

The spin orientation dependence of magnetic hysteresis and microwave ferromagnetic resonance data are investigated in FeCoBSi amorphous thin films. Demagnetization effect allows the weak interface-rooted out-of-plane anisotropy to build up local spin orientation domains under the dominant in-plane anisotropy. As a result, two phase magnetization reversal and double-peak ferromagnetic resonance traces with varying damping behavior are observed. Due to the distribution of in-plane and out-of-plane spin orientations, the ferromagnetic resonance bandwidth has been extensively expanded with the full width at half maximum increased from 1.2 GHz to 3.5 GHz.
Tunable configurational anisotropy in collective magnetization dynamics of Ni80Fe20 nanodot arrays with varying dot shapes
Authors: Mahato B. K. , Choudhury S. , Mandal R. , Barman S. , Otani Y. , Barman A.
Published: June 2015

We present broadband ferromagnetic resonance measurements of tunable spin wave anisotropy in arrays of nanodots with different dot shapes. Magnetization dynamics of the circular dot array shows two modes, while square, diamond, and triangular dot arrays show three, three, and four modes, respectively. Various distinct rotational symmetries in the configurational anisotropy of the nanodot arrays are observed with the variation of dot shape. The observed spin wave modes are reproduced by micromagnetic simulations and the calculated mode profiles show different collective modes determined by internal and stray magnetic fields. Effects of dot shapes are observed in combination with the effects of lattice symmetry and the shape of the boundary of the array. The collective behaviour is observed to be weakest in the diamond shaped dots and strongest in circular shaped dots. This is further confirmed by the stray field calculation. The large variation of spin wave mode frequencies and their configurational anisotropies with dot shapes are important for selection of suitable basis structures for future magnonic crystals.
Effects of a spin-polarized current assisted Ørsted field in magnetization patterning
Authors: Volkov Oleksii M. , Kravchuk Volodymyr P. , Sheka Denis D. , Gaididei Yuri , Mertens Franz G.
Published: June 2015

A spin-polarized electrical current leads to a variety of periodical magnetic structures in nanostripes. In the presence of the Ørsted field, which always assists an electrical current, the basic types of magnetic structures, i.e., a vortex-antivortex crystal and cross-tie domain walls, survive. The Ørsted field prevents saturation of the nanostripe and a longitudinal domain wall appears instead. Possible magnetization structures in stripes with different geometrical and material properties are studied numerically and analytically.
Storage scheduling for optimal energy management in active distribution network considering load, wind, and plug-in electric vehicles uncertainties
Authors: Sedghi M. , Ahmadian A. , Pashajavid E. , Aliakbar-Golkar M.
Published: June 2015

The storage units decrease the operation cost of active distribution network considerably if they are managed optimally. In this paper, the short-term optimal scheduling of stationary batteries is presented. The point estimate method is used for considering uncertainty of load, wind-based distributed generation and plug-in electric vehicles as well as their influence on optimal scheduling. The optimal scheduling consists of minimizing cost objective function under technical constraints. In this paper, the cost objective function is composed of operation and reliability costs which are minimized using Tabu search algorithm. The storage units are used for several objectives, i.e., peak shaving, voltage regulation, and reliability enhancement. The numerical studies show the advantages of batteries for energy management in active distribution network, and the impact of uncertainties on optimal scheduling.
Control of target-normal-sheath-accelerated protons from a guiding cone
Authors: Zou D. B. , Zhuo H. B. , Yang X. H. , Yu T. P. , Shao F. Q. , Pukhov A.
Published: June 2015

It is demonstrated through particle-in-cell simulations that target-normal-sheath-accelerated protons can be well controlled by using a guiding cone. Compared to a conventional planar target, both the collimation and number density of proton beams are substantially improved, giving a high-quality proton beam which maintained for a longer distance without degradation. The effect is attributed to the radial electric field resulting from the charge due to the hot target electrons propagating along the cone surface. This electric field can effectively suppress the spatial spread of the protons after the expansion of the hot electrons.
Reconnection dynamics with secondary tearing instability in compressible Hall plasmas
Authors: Ma Z. W. , Wang L. C. , Li L. J.
Published: June 2015

The dynamics of a secondary tearing instability is systematically investigated based on compressible Hall magnetohydrodynamic. It is found that in the early nonlinear phase of magnetic reconnection before onset of the secondary tearing instability, the geometry of the magnetic field in the reconnection region tends to form a Y-type structure in a weak Hall regime, instead of an X-type structure in a strong Hall regime. A new scaling law is found that the maximum reconnection rate in the early nonlinear stage is proportional to the square of the ion inertial length (γ∝di2) in the weak Hall regime. In the late nonlinear phase, the thin elongated current sheet associated with the Y-type geometry of the magnetic field breaks up to form a magnetic island due to a secondary tearing instability. After the onset of the secondary tearing mode, the reconnection rate is substantially boosted by the formation of the X-type geometries of magnetic field in the reconnection regions. With a strong Hall effect, the maximum reconnection rate linearly increases with the increase of the ion inertial length (γ∝di).
Low-reflection beam refractions by ultrathin Huygens metasurface
Authors: Jia Sheng Li , Wan Xiang , Fu Xiao Jian , Zhao Yong Jiu , Cui Tie Jun
Published: June 2015

We propose a Huygens source unit cell to develop an ultrathin low-reflection metasurface, which could provide extreme controls of phases of the transmitted waves. Both electric and magnetic currents are supported by the proposed unit cell, thus leading to highly efficient and full controls of phases. The coupling between electric and magnetic responses is negligible, which will significantly reduce the difficulty of design. Since the unit cell of metasurface is printed on two bonded boards, the fabrication process is simplified and the thickness of metasurface is reduced. Based on the proposed unit cell, a beam-refracting metasurface with low-reflection is designed and manufactured. Both near-field and far-field characteristics of the beam-refracting metasurface are investigated by simulations and measurements, which indicate that the proposed Huygens metasurface performs well in controlling electromagnetic waves.
The mechanism of the effect of a plasma layer with negative permittivity on the antenna radiation field
Authors: Wang Chunsheng , Liu Hui , Li Xueai , Jiang Binhao
Published: June 2015

A model of a plasma–antenna system is developed to study the mechanism of the effect of the plasma layer on antenna radiation. Results show a plasma layer with negative permittivity is inductive, and thus affects the phase difference between electric and magnetic fields. In the near field of antenna radiation, a plasma layer with proper parameters can compensate the capacitivity of the vacuum and enhance the radiation power. In the far field of antenna radiation, the plasma layer with negative permittivity increases the inductivity of the vacuum and reduces the radiation power.