bluuebunny/crossref_metadata_2025 huggingface dataset:
A Lagrangian framework for deriving triples and quadruples corrections to the CCSD energy
Authors: Eriksen Janus J. , Kristensen Kasper , Kjærgaard Thomas , Jørgensen Poul , Gauss Jürgen
Published: February 2014

Using the coupled cluster Lagrangian technique, we have determined perturbative corrections to the coupled cluster singles and doubles (CCSD) energy that converge towards the coupled cluster singles, doubles, and triples (CCSDT) and coupled cluster singles, doubles, triples, and quadruples (CCSDTQ) energies, considering the CCSD state as the unperturbed reference state and the fluctuation potential as the perturbation. Since the Lagrangian technique is utilized, the energy corrections satisfy Wigner's 2n + 1 rule for the cluster amplitudes and the 2n + 2 rule for the Lagrange multipliers. The energy corrections define the CCSD perturbation series, CCSD(T–n) and CCSD(TQ–n), which are term-wise size extensive to any order in the perturbation. A detailed comparison of the CCSD(TQ–n) series and the CC(2)PT(n) series of Hirata et al. [J. Chem. Phys. 114, 3919 (2001)] has been performed, revealing some deficiencies of the latter related to the target energy of the series and its lack of size extensivity.
Surface dynamics transition during the growth of compositionally graded CrNx films
Authors: Yang J. J. , Miao F. M. , Tang J. , Shu X. Y. , Ma F. , Xu K. W. , Yang Y. Y. , Liao J. L. , Liu N.
Published: February 2014

We report a direct experimental study on the surface dynamics of reactive-sputtered compositionally graded (CG) CrNx films. Based on the dynamic scaling analysis, an intriguing transition of surface dynamics from Family-Vicsek scaling (I regime) to “oscillating” mode (II regime) and then to anomalous rapid-roughening scaling (III regime) is observed. This transition is closely related to the reactive sputtering process of CG nitride films. Especially, it is found that the oscillating behavior of surface dynamics in regime II originates from the alternate growth of crystalline and amorphous phases on the growing surface.
Boron deactivation in heavily boron-doped Czochralski silicon during rapid thermal anneal: Atomic level understanding
Authors: Gao Chao , Lu Yunhao , Dong Peng , Yi Jun , Ma Xiangyang , Yang Deren
Published: February 2014

The changes in hole concentration of heavily boron (B)-doped Czochralski silicon subjected to high temperature rapid thermal anneal (RTA) and following conventional furnace anneal (CFA) have been investigated. It is found that decrease in hole concentration, namely, B deactivation, is observed starting from 1050 °C and increases with RTA temperature. The following CFA at 300–500 °C leads to further B deactivation, while that at 600–800 °C results in B reactivation. It is supposed that the interaction between B atoms and silicon interstitials (I) thus forming BI pairs leads to the B deactivation during the high temperature RTA, and, moreover, the formation of extended B2I complexes results in further B deactivation in the following CFA at 300–500 °C. On the contrary, the dissociation of BI pairs during the following CFA at 600–800 °C enables the B reactivation. Importantly, the first-principles calculation results can soundly account for the above-mentioned supposition.
Multiferroicity and magnetoelectric coupling enhanced large magnetocaloric effect in DyFe0.5Cr0.5O3
Authors: Yin L. H. , Yang J. , Zhang R. R. , Dai J. M. , Song W. H. , Sun Y. P.
Published: February 2014

DyFe0.5Cr0.5O3 has been synthesized using a sol-gel method. It exhibits ferroelectricity at the antiferromagnetic ordering temperature TN1∼261 K. Large magnetocaloric effect (MCE) (11.3 J/kg K at 4.5 T) enhanced by magnetoelectric coupling due to magnetic field and temperature induced magnetic transition was observed. Temperature-dependent Raman study shows an anomalous behavior near TN1 in the phonon modes related to the vibration of Dy atoms and stretching of CrO6/FeO6 octahedra, suggesting the ferroelectricity in DyFe0.5Cr0.5O3 is associated with the spin-phonon coupling with respect to both Dy and Cr/Fe ions. These results suggest routes to obtain high-temperature multiferroicity and large MCE for practical applications.
The behavior of off-state stress-induced electrons trapped at the buffer layer in AlGaN/GaN heterostructure field effect transistors
Authors: Liao W. C. , Chen Y. L. , Chen C. H. , Chyi J. I. , Hsin Y. M.
Published: February 2014

A measurement methodology involving the synchronous switching of gate to source voltage and drain to source voltage (VDS) was proposed for determining the shift of threshold voltage after an AlGaN/GaN heterostructure transistor endures high VDS off-state stress. The measurement results indicated slow electron detrapping behavior. The trap level was determined as (EC – 0.6 eV). Simulation tool was used to analyze the measurement results. The simulation results were consistent with the experimental results; and a relationship between the buffer trap and threshold voltage shift over time was observed.
Efficient and accurate simulation of dynamic dielectric objects
Authors: Barros Kipton , Sinkovits Daniel , Luijten Erik
Published: February 2014

Electrostatic interactions between dielectric objects are complex and of a many-body nature, owing to induced surface bound charge. We present a collection of techniques to simulate dynamicaldielectric objects. We calculate the surface bound charge from a matrix equation using the Generalized Minimal Residue method (GMRES). Empirically, we find that GMRES converges very quickly. Indeed, our detailed analysis suggests that the relevant matrix has a very compact spectrum for all non-degenerate dielectric geometries. Each GMRES iteration can be evaluated using a fast Ewald solver with cost that scales linearly or near-linearly in the number of surface charge elements. We analyze several previously proposed methods for calculating the bound charge, and show that our approach compares favorably.
Classical novae and type I X-ray bursts: Challenges for the 21st century
Authors: Parikh A. , José J. , Sala G.
Published: February 2014

Classical nova explosions and type I X-ray bursts are the most frequent types of thermonuclear stellar explosions in the Galaxy. Both phenomena arise from thermonuclear ignition in the envelopes of accreting compact objects in close binary star systems. Detailed observations of these events have stimulated numerous studies in theoretical astrophysics and experimental nuclear physics. We discuss observational features of these phenomena and theoretical efforts to better understand the energy production and nucleosynthesis in these explosions. We also examine and summarize studies directed at identifying nuclear physics quantities with uncertainties that significantly affect model predictions.
Magnetic transitions driven by temperature in surface oxidized Co0.10Ni0.90/Cu(001) ultrathin films
Authors: Shih Ying-Ta , Shen Wen-He , Lee Kuo-Long , Pan Wei
Published: February 2014

The magnetization of Co0.10Ni0.90/Cu(001) films before and after surface oxidization at 300 K is presented. Before the oxidization, the magnetization of the films in the thickness of 11 to 20 monolayers (ML) is in the in-plane direction at the temperature ranging from 140 K to 300 K. After the oxidization, the magnetizations of the films are in the in-plane direction at the temperature above 200 K, but transit to magnetization demolishment, in-plane-and-out-of-plane co-existence, spin reorientation transition, and coercivity enhancement, for films of 11, 12, 13, and above 15 ML, respectively. The blocking temperature of this film is also 200 K, which implies the transitions might be driven by the ordering of the antiferromagnetic surface oxides. The various magnetizations provide a model system for manipulating the magnetization direction, as well as a spin valve device by combination of the oxidized films.
Epitaxial growth of 100-μm thick M-type hexaferrite crystals on wide bandgap semiconductor GaN/Al2O3 substrates
Authors: Hu Bolin , Su Zhijuan , Bennett Steve , Chen Yajie , Harris Vincent G.
Published: February 2014

Thick barium hexaferrite BaFe12O19 (BaM) films having thicknesses of ∼100 μm were epitaxially grown on GaN/Al2O3 substrates from a molten-salt solution by vaporizing the solvent. X-ray diffraction measurement verified the growth of BaM (001) textured growth of thick films. Saturation magnetization, 4πMs, was measured for as-grown films to be 4.6 ± 0.2 kG and ferromagnetic resonance measurements revealed a microwave linewidth of ∼100 Oe at X-band. Scanning electron microscopy indicated clear hexagonal crystals distributed on the semiconductor substrate. These results demonstrate feasibility of growing M-type hexaferrite crystal films on wide bandgap semiconductor substrates by using a simple powder melting method. It also presents a potential pathway for the integration of ferrite microwave passive devices with active semiconductor circuit elements creating system-on-a-wafer architectures.
Nanocrystalline-Si-dot multi-layers fabrication by chemical vapor deposition with H-plasma surface treatment and evaluation of structure and quantum confinement effects
Authors: Kosemura Daisuke , Mizukami Yuki , Takei Munehisa , Numasawa Yohichiroh , Ohshita Yoshio , Ogura Atsushi
Published: February 2014

100-nm-thick nanocrystalline silicon (nano-Si)-dot multi-layers on a Si substrate were fabricated by the sequential repetition of H-plasma surface treatment, chemical vapor deposition, and surface oxidation, for over 120 times. The diameter of the nano-Si dots was 5–6 nm, as confirmed by both the transmission electron microscopy and X-ray diffraction analysis. The annealing process was important to improve the crystallinity of the nano-Si dot. We investigated quantum confinement effects by Raman spectroscopy and photoluminescence (PL) measurements. Based on the experimental results, we simulated the Raman spectrum using a phenomenological model. Consequently, the strain induced in the nano-Si dots was estimated by comparing the experimental and simulated results. Taking the estimated strain value into consideration, the band gap modulation was measured, and the diameter of the nano-Si dots was calculated to be 5.6 nm by using PL. The relaxation of the q ∼ 0 selection rule model for the nano-Si dots is believed to be important to explain both the phenomena of peak broadening on the low-wavenumber side observed in Raman spectra and the blue shift observed in PL measurements.
Transitional regimes of natural convection in a differentially heated cubical cavity under the effects of wall and molecular gas radiation
Authors: Soucasse L. , Rivière Ph. , Soufiani A. , Xin S. , Le Quéré P.
Published: February 2014

The transition to unsteadiness and the dynamics of weakly turbulent natural convection, coupled to wall or gas radiation in a differentially heated cubical cavity with adiabatic lateral walls, are studied numerically. The working fluid is air with small contents of water vapor and carbon dioxide whose infrared spectral radiative properties are modelled by the absorption distribution function model. A pseudo spectral Chebyshev collocation method is used to solve the flow field equations and is coupled to a direct ray tracing method for radiation transport. Flow structures are identified by means of either the proper orthogonal decomposition or the dynamic mode decomposition methods. We first retrieve the classical mechanism of transition to unsteadiness without radiation, characterized by counter-rotating streamwise-oriented vortices generated at the exit of the vertical boundary layers. Wall radiation through a transparent medium leads to a homogenization of lateral wall temperatures and the resulting transition mechanism is similar to that obtained with perfectly conducting lateral walls. The transition is due to an unstable stratification upstream the vertical boundary layers and is characterized by periodically oscillating transverse rolls of axis perpendicular to the main flow. When molecular gas radiation is accounted for, no periodic solution is found and the transition to unsteadiness displays complex structures with chimneys-like rolls whose axes are again parallel to the main flow. The origin of this instability is probably due to centrifugal forces, as suggested previously for the case without radiation. Above the transition to unsteadiness, at Ra = 3 × 108, it is shown that both wall and gas radiation significantly intensify turbulent fluctuations, decrease the thermal stratification in the core of the cavity, and increase the global circulation.
MgO-hybridized TiO2 interfacial layers assisting efficiency enhancement of solid-state dye-sensitized solar cells
Authors: Sakai Nobuya , Ikegami Masashi , Miyasaka Tsutomu
Published: February 2014

Interfacial modification of a thin TiO2 compact layer (T-CL) by hybridization with MgO enhanced the quantum conversion efficiency of solid-state dye-sensitized solar cells (ssDSSCs) comprising a multilayer structure of transparent electrode/T-CL/dye-sensitized mesoporous TiO2/hole conductor/metal counter electrode. The Mg(CH3COO)2 treatment was employed to introduce a MgO-TiO2 CL (T/M-CL), which enhanced the physical connection and conduction between the CL and mesoporous semiconductor layer as a consecutive interface, owing to the dehydration reaction of Mg(CH3COO)2. The photocurrent density of ssDSSC was increased 33% by the T/M-CL compared with the T-CL, using an equivalent amount of adsorbed dye. The ssDSSC with the T/M-CL yielded the highest efficiency of 4.02% under irradiation at 100 mW cm−2. The electrical impedance spectroscopy showed that the charge-transfer resistance (Rct) of the photoelectrode with T/M-CL was reduced by 300 Ω from the reference non-treated T-CL electrode. Characterized by the intrinsically low Rct of the compact layer, the T/M-CL is capable of improving the photovoltaic performance of solid-state sensitized mesoscopic solar cells.
Radiation power and linewidth of a semifluxon-based Josephson oscillator
Authors: Paramonov M. , Fominsky M. Yu. , Koshelets V. P. , Neumeier B. , Koelle D. , Kleiner R. , Goldobin E.
Published: February 2014

We demonstrate a high-frequency generator operating at ∼200 GHz based on flipping a semifluxon in a Josephson junction of moderate normalized length. The semifluxon spontaneously appears at the π discontinuity of the Josephson phase artificially created by means of two tiny current injectors. The radiation is detected by an on-chip detector (tunnel junction). The estimated radiation power (at the detector) is ∼8 nW and should be compared with the dc power of ∼100 nW consumed by the generator. The measured radiation linewidth, as low as 1.1 MHz, is typical for geometrical (Fiske) resonances, although we tried to suppress such resonances by placing well-matched microwave transformers at its both ends. Making use of a phase-locking feedback loop, we are able to reduce the radiation linewidth to less than 1 Hz measured relative to the reference oscillator and defined just by the resolution of our measurement setup.
Absolute total and partial dissociative cross sections of pyrimidine at electron and proton intermediate impact velocities
Authors: Wolff Wania , Luna Hugo , Sigaud Lucas , Tavares Andre C. , Montenegro Eduardo C.
Published: February 2014

Absolute total non-dissociative and partial dissociative cross sections of pyrimidine were measured for electron impact energies ranging from 70 to 400 eV and for proton impact energies from 125 up to 2500 keV. MOs ionization induced by coulomb interaction were studied by measuring both ionization and partial dissociative cross sections through time of flight mass spectrometry and by obtaining the branching ratios for fragment formation via a model calculation based on the Born approximation. The partial yields and the absolute cross sections measured as a function of the energy combined with the model calculation proved to be a useful tool to determine the vacancy population of the valence MOs from which several sets of fragment ions are produced. It was also a key point to distinguish the dissociation regimes induced by both particles. A comparison with previous experimental results is also presented.
Large and stable emission current from synthesized carbon nanotube/fiber network
Authors: Di Yunsong , Xiao Mei , Zhang Xiaobing , Wang Qilong , Li Chen , Lei Wei , Cui Yunkang
Published: February 2014

In order to obtain a large and stable electron field emission current, the carbon nanotubes have been synthesized on carbon fibers by cold wall chemical vapor deposition method. In the hierarchical nanostructures, carbon fibers are entangled together to form a conductive network, it could provide excellent electron transmission and adhesion property between electrode and emitters, dispersed clusters of carbon nanotubes with smaller diameters have been synthesized on the top of carbon fibers as field emitters, this kind of emitter distribution could alleviate electrostatic shielding effect and protect emitters from being wholly destroyed. Field emission properties of this kind of carbon nanotube/fiber network have been tested, up to 30 mA emission current at an applied electric field of 6.4 V/μm was emitted from as-prepared hierarchical nanostructures. Small current degradation at large emission current output by DC power operation indicated that carbon nanotube/fiber network could be a promising candidate for field emission electron source.
Hysteretic electrical transport in BaTiO3/Ba1−xSrxTiO3/Ge heterostructures
Authors: Ngai J. H. , Kumah D. P. , Ahn C. H. , Walker F. J.
Published: February 2014

We present electrical transport measurements of heterostructures comprised of BaTiO3 and Ba1−xSrxTiO3 epitaxially grown on Ge. Sr alloying imparts compressive strain to the BaTiO3, which enables the thermal expansion mismatch between BaTiO3 and Ge to be overcome to achieve c-axis oriented growth. The conduction bands of BaTiO3 and Ba1−xSrxTiO3 are nearly aligned with the conduction band of Ge, which facilitates electron transport. Electrical transport measurements through the dielectric stack exhibit rectifying behavior and hysteresis, where the latter is consistent with ferroelectric switching.
Polarization measurement of laser-accelerated protons
Authors: Raab Natascha , Büscher Markus , Cerchez Mirela , Engels Ralf , Engin llhan , Gibbon Paul , Greven Patrick , Holler Astrid , Karmakar Anupam , Lehrach Andreas , Maier Rudolf , Swantusch Marco , Toncian Monika , Toncian Toma , Willi Oswald
Published: February 2014

We report on the successful use of a laser-driven few-MeV proton source to measure the differential cross section of a hadronic scattering reaction as well as on the measurement and simulation study of polarization observables of the laser-accelerated charged particle beams. These investigations were carried out with thin foil targets, illuminated by 100 TW laser pulses at the Arcturus laser facility; the polarization measurement is based on the spin dependence of hadronic proton scattering off nuclei in a Silicon target. We find proton beam polarizations consistent with zero magnitude which indicates that for these particular laser-target parameters the particle spins are not aligned by the strong magnetic fields inside the laser-generated plasmas.
Recombination pathways in polymer:fullerene photovoltaics observed through spin polarization measurements
Authors: Etherington Marc K. , Wang Jianpu , Chow Philip C. Y. , Greenham Neil C.
Published: February 2014

We report magnetoconductance measurements on polymer:fullerene photovoltaic devices in the regime of high fields and low temperatures, where spin polarization of injected carriers plays an important role. The current either decreases or increases with magnetic field, depending on whether the interfacial charge-transfer state lies above or below the intramolecular triplet state in energy. Rapid transitions from triplet charge-transfer states to lower-lying triplet excitons constitute an important loss mechanism that is responsible for the negative magnetoconductance observed.
Solution-processed high-performance flexible 9, 10-bis(phenylethynyl)anthracene organic single-crystal transistor and ring oscillator
Authors: Cai Xiaozhou , Ji Deyang , Jiang Lang , Zhao Guangyao , Tan Jiahui , Tian Guofeng , Li Jingze , Hu Wenping
Published: February 2014

Organic semiconductor of 9, 10-bis(phenylethynyl)anthracene (BPEA) single crystal ribbon with ultra-long length has been prepared by solution drop casting method, where the growth direction was controlled with the seed crystal. The BPEA single crystal ribbon based field-effect transistors show high hole mobility up to 3.2 cm2/V·s, and the inverters exhibited the highest gain of 92. The complex device such as 5-stage ring oscillator consisting of 10 transistors was also constructed on a single crystal ribbon. This straightforward methodology was applied to fabricate plastic transistors on the flexible substrate, showing high performance even after repeatedly bending of 300 times.
Magnetoimpedance of thin film meander with composite coating layer containing Ni nanoparticles
Authors: Lodewijk K. J. , Fernandez E. , Garcia-Arribas A. , Kurlyandskaya G. V. , Lepalovskij V. N. , Safronov A. P. , Kooi B. J.
Published: February 2014

Giant magnetoimpedance (GMI) [FeNi/Cu]4/FeNi/Cu/[FeNi/Cu]4/FeNi sensing meander elements were designed and tested aiming to develop a new instrumentation for characterization of polymer/magnetic nanoparticles composites. Acrylic copolymer of 95% of butyl methacrylate and 5% of methacrylic acid was used as polymer matrix of the composite. It was shown that GMI meander sensing elements are capable of detecting Ni nanoparticles spread in the polymer matrix. Polymeric composites filled with magnetic nanoparticles in small concentration are able to enhance GMI meander sensitivity.
Hard x-ray photoelectron spectroscopy study of Ge2Sb2Te5; as-deposited amorphous, crystalline, and laser-reamorphized
Authors: Richter Jan H. , Fons Paul , Kolobov Alex V. , Ueda Shigenori , Yoshikawa Hideki , Yamashita Yoshiyuki , Ishimaru Satoshi , Kobayashi Keisuke , Tominaga Junji
Published: February 2014

We have investigated the electronic structure of as-deposited, crystalline, and laser-reamorphized Ge2Sb2Te5 using high resolution, hard x-ray photoemission spectroscopy. A shift in the Fermi level as well as a broadening of the spectral features in the valence band and the Ge 3d level between the amorphous and crystalline state is observed. Upon amorphization, Ge 3d and Sb 4d spectra show a surprisingly small breaking of resonant bonds and changes in the bonding character as evidenced by the very similar density of states in all cases.
Observation of an unusual optical switching effect in relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3-Pb(Zr0.53,Ti0.47)O3 transparent ceramics
Authors: Zhao Wei , Ruan Wei , Zeng Jiangtao , Huang Lizhu , Zhao Kunyu , Zheng Liaoying , Zeng Huarong , Zhou Yibo , Yang Heji , Ruan Xuezheng , Li Guorong
Published: February 2014

We present an unusual optical switching effect in relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3-Pb(Zr0.53,Ti0.47)O3 transparent ceramics under strong AC electric fields, which is accompanied by a peculiar dielectric response rarely reported previously and attributed to the disruption of the ferroelectric domain structure by the strong AC field. The results provide further understanding on the domain behaviors under electric fields of the relaxor ferroelectrics and the potential for advancing electro-optic applications.
Loss compensation of extraordinary optical transmission
Authors: Beijnum Frerik van , van Veldhoven Peter J. , Jan Geluk Erik , Hooft Gert W. 't , van Exter Martin P.
Published: February 2014

In the past decade, metal hole arrays have been studied intensively in the context of extraordinary optical transmission (EOT). Recently it was shown that surface plasmons on optically pumped hole arrays can show laser action. So far, however, it is not demonstrated that the optical transmission of these arrays can also be increased using gain. In this Letter, we present a dramatic increase of the EOT via loss compensation of surface plasmons, accompanied by spectral narrowing of the resonance. These experiments allow us to quantify the modal gain experienced by the surface plasmon. Interestingly, the transmission minimum of the Fano-resonance becomes smaller.
Polymer-loaded propagating modes on a one-dimensional photonic crystal
Authors: Han Lu , Zhang Douguo , Chen Yikai , Wang Ruxue , Zhu Liangfu , Wang Pei , Ming Hai , Badugu Ramachandram , Lakowicz Joseph R.
Published: February 2014

We numerically and experimentally demonstrate that a polymer film-coated one-dimensional photonic crystal (1DPC) can sustain transverse electric (TE) polarized modes without the limit of guided layer's thickness. Our results indicate that two propagating modes are existing inside the polymer film, the first one is the TE polarized Bloch surface wave, and the second one is the TE polarized guided mode. Here in, the evolution of these two modes with change in the polymer film thickness is presented. Our numerical simulation results are in well-agreement with the experimental data obtained using back focal plane imaging.
Thin-film topological insulator-ferromagnet heterostructures for terahertz detection
Authors: Li Xiaodong , Semenov Yuriy G. , Kim Ki Wook
Published: February 2014

An atomically thin topological insulator is investigated theoretically for long-wavelength photodetection when it interacts with a magnetic material. Through the coupling between top and bottom surfaces as well as the exchange interaction with the proximate ferromagnet, the distribution of optically excited carriers exhibits unique patterns that depend sensitively on the frequency of the incoming light. This effect results in the generation of strong nonzero photocurrent, leading potentially to room-temperature detection of far-infrared/THz radiation with the advantage of low noise and fast response. The ease of frequency tuning by an external electrical bias offers an added versatility in the realistic implementation.
A simple scanning spectrometer based on a stretchable elastomeric reflective grating
Authors: Ghisleri C. , Potenza M. A. C. , Ravagnan L. , Bellacicca A. , Milani P.
Published: February 2014

We report a scanning optical spectrometer based on the use of a stretchable elastomeric reflective grating. The grating is obtained by supersonic cluster beam implantation of silver nanoparticles on polydimethylsiloxane previously grooved by molding to create a replica of a commercial digital versatile disk grating. The use of a stretchable grating allows the spectrometer spanning the whole optical wavelength range by solely extending the diffraction element by more than 100% of its original dimensions. The stretchable reflective optical grating shows excellent performances and stability upon thousands of stretching cycles. The use of this elastomeric element makes the optical layout and the mechanics of the spectrometer extremely simple and advantageous for those applications where spectral resolution is not a major requirement. As a proof of principle, we present the absorption spectrum of Rhodamine B in solution obtained by our spectrometer and compared to commercial instruments.
Disorder-modulated microwave absorption properties of carbon-coated FeCo nanocapsules
Authors: Jiang J. J. , Li X. J. , Han Z. , Li D. , Wang Z. H. , Geng D. Y. , Ma S. , Liu W. , Zhang Z. D.
Published: February 2014

Microwave absorption properties of three kinds of carbon-coated FeCo nanocapsules with modulated disorder levels of carbon shells have been investigated. The disorder level in carbon shells of Fe55Co45/(C, silicides) nanocapsules with silicides-doped carbon shells, Fe60Co40/C nanocapsules with amorphous carbon shells, and Fe55Co45/C nanocapsules with onion-like graphite shells were characterized by Raman spectra, indicating a disorder increase from 0.66 for the Fe55Co45/C to 1.06 for the Fe60Co40/C and then to 2.10 for the Fe55Co45/(C, silicides) nanocapsules. Reflection loss peak position redshifts to lower frequency with increasing carbon disorder, which should be attributed to the increase of the disorder in carbon shells and different charge transfers between FeCo-C and FeCo-Si at the core/shell interface in the Fe55Co45/(C, silicides) nanocapsules.
Spin-transfer switching of orthogonal spin-valve devices at cryogenic temperatures
Authors: Ye L. , Gopman D. B. , Rehm L. , Backes D. , Wolf G. , Ohki T. , Kirichenko A. F. , Vernik I. V. , Mukhanov O. A. , Kent A. D.
Published: February 2014

We present the quasi-static and dynamic switching characteristics of orthogonal spin-transfer devices incorporating an out-of-plane magnetized polarizing layer and an in-plane magnetized spin valve device at cryogenic temperatures. Switching at 12 K between parallel and anti-parallel spin-valve states is investigated for slowly varied current as well as for current pulses with durations as short as 200 ps. We demonstrate 100% switching probability with current pulses 0.6 ns in duration. We also present a switching probability diagram that summarizes device switching operation under a variety of pulse durations, amplitudes, and polarities.
Magnetization stability analysis of the Stoner-Wohlfarth model under a spin-polarized current with a tilted polarization
Authors: Wang Zhiyuan , Sun Z. Z.
Published: February 2014

The stationary-state solutions of magnetization dynamics under a spin-polarized current that was polarized in an arbitrary direction were investigated by solving the Landau-Lifshitz-Gilbert-Slonczewski equation for a single-domain magnet. Taking into consideration the uniaxial magnetic anisotropy, the equilibrium directions of the magnetization vectors were analytically obtained by solving an algebraic cubic equation. It was found that one to three pairs of magnetization equilibrium states existed, depending on the current intensity and the direction of the spin polarization. By numerically analyzing the stabilities of these equilibrium states, the threshold switching current for the reversing the magnetic vector was obtained under different current polarization configurations, which may be useful for use in future spintronics devices.
Performance improvements of a split-off band infra-red detector using a graded barrier
Authors: Pitigala P. K. D. D. P. , Lao Y. F. , Perera A. G. U. , Li L. H. , Linfield E. H. , Liu H. C.
Published: February 2014

Uncooled split-off band infrared detectors have been demonstrated with an operational device response in the 3–5 μm range. We have shown that it is possible to enhance this device response through reducing the recapture rate by replacing one of the commonly used flat barriers in the device with a graded barrier, which was grown using a “digital alloying” approach. Responsivity of approximately 80 μA/W (D* = 1.4 × 108 Jones) were observed at 78 K under a 1 V applied bias, with a peak response at 2.8 μm. This is an improvement by a factor of ∼25 times compared to an equivalent device with a flat barrier. This enhancement is due to improved carrier transport resulting from the superlattice structure, and a low recapture rate enabled by a reduced distance to the image force potential peak in the graded barrier. The device performance can be further improved by growing a structure with repeats of the single emitter layer reported here.
Coercivity enhancement in V2O3/Ni bilayers driven by nanoscale phase coexistence
Authors: de la Venta J. , Wang Siming , Saerbeck T. , Ramírez J. G. , Valmianski I. , Schuller Ivan K.
Published: February 2014

We studied the temperature dependence of coercivity and magnetization of V2O3/Ni bilayers across the Structural Phase Transition in V2O3. We found a coercivity peak that coincides with the V2O3 phase transition on top of an overall increase of the coercivity with decreasing temperature. We propose that this sharp increase arises from a length scale competition between magnetic domains of Ni and phase coexistence during the V2O3 phase transition. This model is supported by micromagnetic simulations and shows that magnetic properties of ferromagnetic films are strongly affected by a proximal first order phase transition.
Size and boundary scattering controlled contribution of spectral phonons to the thermal conductivity in graphene ribbons
Authors: Shen Yulu , Xie Guofeng , Wei Xiaolin , Zhang Kaiwang , Tang Minghua , Zhong Jianxin , Zhang Gang , Zhang Yong-Wei
Published: February 2014

Although graphene holds great promise in thermal applications owing to its superior thermal conductivity, an intriguing question remains as to which polarizations and frequencies are dominant in its heat conduction. In this work, by incorporating the direction-dependent phonon-boundary scattering and the special selection rule for three-phonon scattering into the linearized phonon Boltzmann transport equation, we systematically investigate the relative contributions from longitudinal-acoustic, transverse-acoustic, and out-of-plane acoustic (ZA) branches to the thermal conductivity of graphene ribbons, focusing on the effects of their size and temperature. We find that the relative contribution from ZA branch to heat conduction increases with decreasing the size, specularity parameter, and temperature of graphene ribbons. Our analysis reveals that this change arises from the huge difference in the phonon dispersion and in the phonon mean free path of Umklapp process between in-plane and out-of-plane branches.
An experimental verification of metamaterial coupled enhanced transmission for antenna applications
Authors: Pushpakaran Sarin V. , Raj Rohith K. , Pradeep Anju , Ouseph Lindo , Hari Mridula , Chandroth Aanandan , Pezholil Mohanan , Kesavath Vasudevan
Published: February 2014

Inspired by the work of Bethe on electromagnetic transmission through subwavelength hole, there has been immense interest on the extraordinary transmission through subwavelength slot/slit on metal plates. The invention of metamaterials has boosted the extra ordinary transmission through subwavelength slots. We examine computationally and experimentally the concept of metamaterial cover using an array of split ring resonators (SRRs), for enhancing the transmission in a stacked dipole antenna working in the S band. The front to back ratio is considerably improved by enhancing the magnetic resonant strength in close proximity of the slit of the upper parasitic dipole. The effect of stacking height of the SRR monolayer on the resonant characteristics of the split ring resonators and its effect on antenna radiation characteristics has been studied.
Laser assisted dye-sensitized solar cell sealing: From small to large cells areas
Authors: Ribeiro Fernando , Maçaira José , Mesquita Isabel , Gabriel Joaquim , Andrade Luísa , Mendes Adélio
Published: February 2014

Dye sensitized solar cells (DSCs) modules are an emergent photovoltaic technology but still present some weaknesses in terms of long-term stability: sealing is presently the Achilles' heel of DSCs, which is currently preventing their commercialization. Thermoplastic sealants are normally used to bond the two glass substrates of a DSC. However, these thermoplastic sealants, such as Surlyn®, are permeable towards ambient water vapor, UV sensitive, and they cannot be used above 60 °C. Laser assisted glass-frit sealing is a very interesting alternative sealing technique as it has been demonstrated on microelectromechanical systems assembly. For these applications, the laser is shot around the sealing perimeter several times in a loop pattern. Nevertheless, for sealing large areas without heating the samples, this method cannot be applied since the laser loop takes more than 1 s, which is too long for an effective low-temperature glass-frit sealing. At present, work is described a laser assisted sealing technique that is independent of the sealing border format. This technique is applied to several cells and modules of different shapes and sizes. The technique is suitable for DSCs manufacture and can be implemented in an inline production plant. For the same cell format, efficiencies of the glass-sealed and conventional sealing were compared. Stability studies were also presented to evidence the effectiveness of the hermetic sealing obtained with the newly developed sealing process of DSCs devices.
Untangling the Spaces of High Technology in Malaysia
Authors: Phelps Nicholas A , Dawood Sharifah R S
Published: February 2014

Designated high-tech spaces such as science and high-technology parks have come to the fore as vehicles for promoting local and regional economic development in many nations. The evidence of their efficacy is mixed and reflects contradictions in the roles they are asked to perform in the service of national economic modernization. Indeed, in this respect and in many instances, their value may be largely political and rhetorical. Malaysia is a case in point and one we focus on in this paper, where we discuss the contribution of high-tech spaces—Kulim High-Tech Park, Technology Park Malaysia, BioXCell, and the multimedia supercorridor—to the political economy of economic modernization. Drawing on original interview material, we highlight the tangled intraterritorial and extraterritorial geographies in which these privileged high-tech spaces are positioned.
Biodiversity, Purity, and Death: Conservation Biology as Biopolitics
Authors: Biermann Christine , Mansfield Becky
Published: February 2014

This paper draws on the Foucauldian notion of biopower to renarrate the development of conservation science in the US as a form of liberal biopolitical rule. With its emphasis on making nature live, conservation marks a shift away from a sovereign form of rule that emphasized subduing and controlling nature; today, nature is ruled not by the sword but by science. Through a discussion of key concepts in conservation biology—populations in crisis; evolution and its future orientation; extinction as death that is necessary for life; and diversity as purity—we illustrate the truth discourses, underlying logics, and calculative technologies by which distinctions within nonhuman life are made and made meaningful. We argue that conservation is biopolitical not just in that it moves from controlling individuals to statistically managing populations and species, but also in that it extends the racialized logic of abnormality in its core notions of biological diversity and purity. In the logics of conservation and race, life produces diversity, conceived as variety of biological kinds; within that diversity exist kinds that foster ongoing life, which should be maximized, and kinds that are threats, which should be let die in the name of life in general.
Measuring the Effects through Time of the Influence of Visuomotor and Visuotactile Synchronous Stimulation on a Virtual Body Ownership Illusion
Authors: Kokkinara Elena , Slater Mel
Published: February 2014

Previous studies have examined the experience of owning a virtual surrogate body or body part through specific combinations of cross-modal multisensory stimulation. Both visuomotor (VM) and visuotactile (VT) synchronous stimulation have been shown to be important for inducing a body ownership illusion, each tested separately or both in combination. In this study we compared the relative importance of these two cross-modal correlations, when both are provided in the same immersive virtual reality setup and the same experiment. We systematically manipulated VT and VM contingencies in order to assess their relative role and mutual interaction. Moreover, we present a new method for measuring the induced body ownership illusion through time, by recording reports of breaks in the illusion of ownership (‘breaks’) throughout the experimental phase. The balance of the evidence, from both questionnaires and analysis of the breaks, suggests that while VM synchronous stimulation contributes the greatest to the attainment of the illusion, a disruption of either (through asynchronous stimulation) contributes equally to the probability of a break in the illusion.
Attractiveness Difference Magnitude Affected by Context, Range, and Categorization
Authors: Forsythe Matthew , Zellner Debra , Cogan Elizabeth , Parker Scott
Published: February 2014

Previous studies have shown that, when subjects view hedonically positive stimuli followed by stimuli of lesser hedonic value, their preference between the stimuli of lesser hedonic value decreases. This is hedonic condensation. In addition, its opposite, hedonic expansion, occurs when subjects view less hedonically positive stimuli followed by more hedonically positive stimuli. Experiment 1 showed both hedonic condensation and expansion in subjects who viewed pictures of unattractive and moderately attractive faces. Experiment 2 showed that, when subjects were instructed to view the stimuli as coming from two different groups, hedonic expansion but not hedonic condensation was eliminated. Experiment 3 showed that increasing the attractiveness difference between the attractive and unattractive faces eliminated all effects of context on subjects' attractiveness difference judgments. Experiment 4 showed that forcing subjects to categorize the extremely attractive and unattractive faces into the same group resulted in hedonic expansion among attractive faces but not condensation among the unattractive faces. These results suggest that, as hedonic contrast changes the hedonic values of stimuli, it also changes the attention paid to those stimuli, thereby altering the degree of preference between them. Manipulations that prevent a shift in hedonic value also block a shift in the magnitude of the preference judgments.
Neanderthal Paintings? Production of Prototypical Human (Homo Sapiens) Faces Shows Systematic Distortions
Authors: Carbon Claus-Christian , Wirth Benedikt Emanuel
Published: February 2014

People's sketches of human faces seem to be systematically distorted: The eye position is always higher than in reality. This bias was experimentally analyzed by a series of experiments varying drawing conditions. Participants either drew prototypical faces from memory (studies 1 and 2: free reconstruction; study 3: cued reconstruction) or directly copied average faces (study 4). Participants consistently showed this positioning bias, which is even in accord with facial depictions published in influential research articles by famous face researchers (study 5). We discuss plausible explanations for this reliable and stable bias, which is coincidentally similar to the morphology of Neanderthals.
Temperature-controlled Deposition of Copper(I) Oxide and Metallic Copper Nanostructures from Single-source Molecular Precursor
Authors: Shahid Muhammad , Mazhar Muhammad , Tahir Asif Ali , Rauf Muhammad Khawar , Raftery James
Published: February 2014

A simple method of depositing morphology- and phase-tailored thin films of copper(i) oxide and metallic copper from [Cu(dmae)(TFA)]4·CH2Cl2 (1), where dmae is N,N-dimethylaminoethanolato and TFA is trifluoroacetato, on glass substrates by aerosol-assisted chemical vapour deposition is demonstrated. The tetrameric precursor 1 was synthesized and its structure was determined by single-crystal X-ray crystallography. Precursor 1 was applied for the deposition of nanostructured thin films of copper(i) oxide and copper nanowires at 250 and 375°C respectively. The deposited thin films were characterized by powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray diffraction, and ultraviolet–visible spectroscopy. The results indicate that the phase and morphology of the deposited material are strongly dependent on deposition temperature. UV-vis studies reveal that copper(i) oxide films with a band gap of 2.48 eV may find possible applications in tandem photoelectrochemical devices as light-absorbing material.
Diffusion limitation of zinc fluxes into wheat roots, PLM and DGT devices in the presence of organic ligands
Authors: Gramlich A. , Tandy S. , Frossard E. , Eikenberg J. , Schulin R.
Published: February 2014

Environmental context
Zinc is an essential micronutrient for plants and many arid areas of the world have zinc-deficient soils. The bioavailability of Zn to plants is influenced by diffusion limitations and complex lability in the soil solution. To identify the relative importance of these two factors, we investigated the influence of diffusion layer thickness on Zn uptake by wheat and by two bio-mimetic devices in the presence of ethylenediaminetetraacetic acid and two natural ligands found in soil.

Abstract
Organic ligands can increase metal mobility in soils. The extent to which this can contribute to plant metal uptake depends among others, on complex lability and diffusion limitations in solute transfer from the soil solution to root uptake sites. We investigated the influence of diffusion layer thickness on zinc uptake by wheat seedlings in the presence of ethylenediaminetetraacetic acid (EDTA), citrate and histidine with similar free Zn by measuring 65Zn uptake from stirred, non-stirred and agar-containing solutions. Analogous experiments were performed using permeation liquid membranes (PLM) and ‘diffusive gradients in thin films’ (DGT) probes as bio-mimetic devices. In treatments with low EDTA concentrations (~2µM) or ligand-free Zn solution, increasing diffusion layer thickness reduced Zn fluxes into roots to a similar extent as into PLM and DGT probes, indicating reduced uptake attributable to diffusion limitation. In the citrate treatments root Zn influx was similar to EDTA treatments under stirred conditions, but increasing diffusion layer thickness did not affect Zn uptake. This suggests complex dissociation compensated for reduced Zn2+ diffusion and that the entire complexes were not taken up. The Zn root influxes in the histidine treatments were found to be on average by a factor of 2.5 higher than in the citrate treatments and they also showed no decrease in non-stirred and agar treatments. Dissociation kinetics inferred from PLM measurements explained a large part, although not all, of the increased Zn uptake by the plants in the presence of histidine. The difference may be a result of the uptake of neutral or positive Zn–histidine complexes. The results of this study confirm that labile complexes can contribute to Zn uptake by wheat either through diffusion limitation and complex dissociation or through uptake of entire complexes, depending on the nature of the ligands.
Variation in mesophyll conductance among Australian wheat genotypes
Authors: Jahan Eisrat , Amthor Jeffrey S. , Farquhar Graham D. , Trethowan Richard , Barbour Margaret M.
Published: February 2014

CO2 diffusion from substomatal intercellular cavities to sites of carboxylation in chloroplasts (mesophyll conductance; gm) limits photosynthetic rate and influences leaf intrinsic water-use efficiency (A/gsw). We investigated genotypic variability of gm and effects of gm on A/gsw among eleven wheat (Triticum aestivum L.) genotypes under light-saturated conditions and at either 2 or 21% O2. Significant variation in gm and A/gsw was found between genotypes at both O2 concentrations, but there was no significant effect of O2 concentration on gm. Further, gm was correlated with photosynthetic rate among the 11 genotypes, but was unrelated to stomatal conductance. The effect of leaf age differed between genotypes, with gm being lower in older leaves for one genotype but not another. This study demonstrates a high level of variation in gm between wheat genotypes; 0.5 to 1.0 μmol m−2 s−1 bar−1. Further, leaf age effects indicate that great care must be taken to choose suitable leaves in studies of genotypic variation in gm and water-use efficiency.