bluuebunny/crossref_metadata_2025 huggingface dataset:
Benzodithiophene homopolymers synthesized by Grignard metathesis (GRIM) and Stille coupling polymerizations
Authors: Magurudeniya Harsha D. , Kularatne Ruvini S. , Rainbolt Elizabeth A. , Bhatt Mahesh P. , Murphy John W. , Sheina Elena E. , Gnade Bruce E. , Biewer Michael C. , Stefan Mihaela C.
Published: April 2014

Poly{4,8-bis(5-dodecylthiophene-2-yl)benzo[1,2-b:4,5-b′]dithiophene} has been synthesized by GRIM polymerization (P1) and Stille coupling polymerization (P2). The optoelectronic properties of the polymers were investigated.
Heteroleptic copper(i)–polypyridine complexes as efficient sensitizers for dye sensitized solar cells
Authors: Sandroni Martina , Favereau Ludovic , Planchat Aurelien , Akdas-Kilig Huriye , Szuwarski Nadine , Pellegrin Yann , Blart Errol , Le Bozec Hubert , Boujtita Mohammed , Odobel Fabrice
Published: April 2014

Record photoconversion efficiency was achieved in DSC with stable heteroleptic bisdiimine complexes prepared by HETPHEN strategy.
Gold nanorod-seeded synthesis of Au@Ag/Au nanospheres with broad and intense near-infrared absorption for photothermal cancer therapy
Authors: Ye Xiaosheng , Shi Hui , He Xiaoxiao , Wang Kemin , Li Duo , Qiu Pengchao
Published: April 2014

A shape-controllable and spectrum-adjustable synthesis strategy is proposed to develop Au@Ag/Au nanoparticles with intense NIR-absorption, efficacious thermotherapy and low dark-cytotoxicity.
Glypican-3 antibody functionalized Prussian blue nanoparticles for targeted MR imaging and photothermal therapy of hepatocellular carcinoma
Authors: Li Zhenglin , Zeng Yongyi , Zhang Da , Wu Ming , Wu Lingjie , Huang Aimin , Yang Huanghao , Liu Xiaolong , Liu Jingfeng
Published: April 2014

MRI-guided photothermal therapy is becoming a more widely accepted minimally invasive technique.
5,6-Difluorobenzothiadiazole and silafluorene based conjugated polymers for organic photovoltaic cells
Authors: Li Guangwu , Kang Chong , Gong Xue , Zhang Jicheng , Li Weiwei , Li Cuihong , Dong Huanli , Hu Wenping , Bo Zhishan
Published: April 2014

Three novel 5,6-difluorobenzothiadiazole and silafluorene based conjugated polymers have been synthesized and used as donor materials for polymer solar cells.
Ectopic lipid storage in non-alcoholic fatty liver disease is not mediated by impaired mitochondrial oxidative capacity in skeletal muscle
Authors: Cuthbertson Daniel J. , Irwin Andrew , Sprung Victoria S. , Jones Helen , Pugh Christopher J. A. , Daousi Christina , Adams Valerie L. , Bimson William E. , Shojaee-Moradie Fariba , Richardson Paul , Umpleby A. Margot , Wilding John P. , Kemp Graham J.
Published: April 2014

Non-alcoholic fatty liver disease (NAFLD), characterized by lipid deposition within the liver [intrahepatocellular lipid (IHCL)], is associated with insulin resistance and the metabolic syndrome (MS). It has been suggested that impaired skeletal muscle mitochondrial function may contribute to ectopic lipid deposition, and the associated MS, by altering post-prandial energy storage. To test this hypothesis, we performed a cross-sectional study of 17 patients with NAFLD [mean±S.D.; age, 45±11 years; body mass index (BMI), 31.6±3.4 kg/m2] and 18 age- and BMI-matched healthy controls (age, 44±11 years; BMI, 30.5±5.2 kg/m2). We determined body composition by MRI, IHCL and intramyocellular (soleus and tibialis anterior) lipids (IMCLs) by proton magnetic resonance spectroscopy (1H-MRS) and skeletal muscle mitochondrial function by dynamic phosphorus magnetic resonance spectroscopy (31P-MRS) of quadriceps muscle. Although matched for BMI and total adiposity, after statistical adjustment for gender, patients with NAFLD (defined by IHCL ≥ 5.5%) had higher IHCLs (25±16% compared with 2±2%; P<0.0005) and a higher prevalence of the MS (76% compared with 28%) compared with healthy controls. Despite this, the visceral fat/subcutaneous fat ratio, IMCLs and muscle mitochondrial function were similar between the NAFLD and control groups, with no significant difference in the rate constants of post-exercise phosphocreatine (PCr) recovery (1.55±0.4 compared with 1.51±0.4 min−1), a measure of muscle mitochondrial function. In conclusion, impaired muscle mitochondrial function does not seem to underlie ectopic lipid deposition, or the accompanying features of the MS, in patients with NAFLD.
Collapse of the turbulent dissipative range on Kolmogorov scales
Authors: Antonia R. A. , Djenidi L. , Danaila L.
Published: April 2014

It is pointed out that the collapse of the turbulent dissipative range on Kolmogorov scales does not require either of the two major assumptions in Kolmogorov's [“The local structure of turbulence in incompressible viscous fluid for very large Reynolds numbers,” Dokl. Akad. Nauk USSR 30, 299 (1941)] similarity hypothesis, i.e., Rλ, the Taylor microscale Reynolds number, is very large and local isotropy is satisfied. In particular, the Kolmogorov velocity and length scales are shown to be the appropriate normalization scales when the large-scale terms in the transport equations for the second-order statistics can be neglected. Evidence for this scaling is discussed critically on the basis of the available data. It is also shown that this scaling breaks down when Rλ becomes too small, typically below 20.
Enhanced von Weizsäcker Wang-Govind-Carter kinetic energy density functional for semiconductors
Authors: Shin Ilgyou , Carter Emily A.
Published: April 2014

We propose a new form of orbital-free (OF) kinetic energy density functional (KEDF) for semiconductors that is based on the Wang-Govind-Carter (WGC99) nonlocal KEDF. We enhance within the latter the semi-local von Weizsäcker KEDF term, which is exact for a single orbital. The enhancement factor we introduce is related to the extent to which the electron density is localized. The accuracy of the new KEDF is benchmarked against Kohn-Sham density functional theory (KSDFT) by comparing predicted energy differences between phases, equilibrium volumes, and bulk moduli for various semiconductors, along with metal-insulator phase transition pressures. We also compare point defect and (100) surface energies in silicon for a broad test of its applicability. This new KEDF accurately reproduces the exact non-interacting kinetic energy of KSDFT with only one additional adjustable parameter beyond the three parameters in the WGC99 KEDF; it exhibits good transferability between semiconducting to metallic silicon phases and between various III-V semiconductors without parameter adjustment. Overall, this KEDF is more accurate than previously proposed OF KEDFs (e.g., the Huang-Carter (HC) KEDF) for semiconductors, while the computational efficiency remains at the level of the WGC99 KEDF (several hundred times faster than the HC KEDF). This accurate, fast, and transferable new KEDF holds considerable promise for large-scale OFDFT simulations of metallic through semiconducting materials.
Ultra-wideband polarization conversion metasurfaces based on multiple plasmon resonances
Authors: Chen Hongya , Wang Jiafu , Ma Hua , Qu Shaobo , Xu Zhuo , Zhang Anxue , Yan Mingbao , Li Yongfeng
Published: April 2014

We propose to realize ultra-wideband polarization conversion metasurfaces in microwave regime through multiple plasmon resonances. An ultra-wideband polarization conversion metasurface is designed using a double-head arrow structure and is further demonstrated both numerically and experimentally. Four plasmon resonances are generated by electric and magnetic resonances, which lead to bandwidth expansion of cross-polarization reflection. The simulated results show that the maximum conversion efficiency is nearly 100% at the four plasmon resonance frequencies and a 1:4 3 dB bandwidth can be achieved for both normally incident x- and y-polarized waves. Experimental results agree well with simulation ones.
Dynamics on modular networks with heterogeneous correlations
Authors: Melnik Sergey , Porter Mason A. , Mucha Peter J. , Gleeson James P.
Published: April 2014

We develop a new ensemble of modular random graphs in which degree-degree correlations can be different in each module, and the inter-module connections are defined by the joint degree-degree distribution of nodes for each pair of modules. We present an analytical approach that allows one to analyze several types of binary dynamics operating on such networks, and we illustrate our approach using bond percolation, site percolation, and the Watts threshold model. The new network ensemble generalizes existing models (e.g., the well-known configuration model and Lancichinetti-Fortunato-Radicchi networks) by allowing a heterogeneous distribution of degree-degree correlations across modules, which is important for the consideration of nonidentical interacting networks.
A model for phosphate glass topology considering the modifying ion sub-network
Authors: Hermansen Christian , Mauro John C. , Yue Yuanzheng
Published: April 2014

In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent with available structural data by NMR and molecular dynamics simulations and with dynamic data such glass transition temperature (Tg) and liquid fragility (m). Alkali phosphate glasses are exemplary systems for developing constraint model since the modifying cation network plays an important role besides the primary phosphate network. The proposed topological model predicts the changing trend of the Tg and m with increasing alkali oxide content for alkali phosphate glasses, including an anomalous minimum at around 20 mol.% alkali oxide content. We find that the minimum in Tg and m is caused by increased connectivity of the modifying ion sub-network, as the alkali ions must share non-bonding oxygen to satisfy their coordination requirements at higher alkali oxide contents. We argue that the systematically decreasing the Tg values of alkali phosphate glasses from Li2O to Na2O to Cs2O could be caused by a weakening of the modifying ion sub-network and can be accounted for by lower constraint onset temperatures.
Fabrication of carbon nanotube film directly grown on conductive stainless steel film and application to dielectrophoretic nanoparticle capture
Authors: Sano Noriaki , Nakamura Tamon , Tamon Hajime , Suntornlohanakul Tatporn , Poonjarernsilp Chantamanee , Charinpanitkul Tawatchai
Published: April 2014

Multi-walled carbon nanotubes (CNTs) were synthesized directly on stainless steel film thermally deposited on an alumina plate. To activate the growth of CNTs, the stainless steel film was reduced in H2 stream without oxidation step. The electrical resistivity of the CNT film synthesized by this way turned to be 1/190 of CNT film synthesized by a conventional way using catalyst preparation method with magnetron sputtering. Dielectrophoretic (DEP) particle capture was demonstrated using the patterned CNT film synthesized on stainless steel film, and it was observed that carbon nanohorns (CNHs) dispersed with Pd nanoparticles (Pd-CNHs) and Pd-Au alloy nanoparticles (Pd/Au-CNHs) were captured at the CNT electrodes due to the high electric field strength there. In this DEP capture, Pd-CNHs were enriched in the present condition. The temperature to deposit stainless steel film and the influence of oxidation step were also investigated for the growth of CNTs.
Design and development of ultra-wideband 3 dB hybrid coupler for Ion cyclotron resonance frequency heating in tokamak
Authors: Yadav Rana Pratap , Kumar Sunil , Kulkarni S. V.
Published: April 2014

Design and development of a high power ultra-wideband, 3 dB tandem hybrid coupler is presented and its application in ICRF heating of the tokamak is discussed. In order to achieve the desired frequency band of 38–112 MHz and 200 kW power handling capability, the 3 dB hybrid coupler is developed using two 3-element 8.34 ± 0.2 dB coupled lines sections in tandem. In multi-element coupled lines, junctions are employed for the joining of coupled elements that produce the undesirable reactance called junction discontinuity effect. The effect becomes prominent in the high power multi-element coupled lines for high frequency (HF) and very high frequency(VHF) applications because of larger structural dimensions. Junction discontinuity effect significantly deteriorates coupling and output performance from the theoretical predictions. For the analysis of junction discontinuity effect and its compensation, a theoretical approach has been developed and generalized for n-element coupled lines section. The theory has been applied in the development of the 3 dB hybrid coupler. The fabricated hybrid coupler has been experimentally characterized using vector network analyzer and obtained results are found in good agreement with developed theory.
Fast, multi-channel real-time processing of signals with microsecond latency using graphics processing units
Authors: Rath N. , Kato S. , Levesque J. P. , Mauel M. E. , Navratil G. A. , Peng Q.
Published: April 2014

Fast, digital signal processing (DSP) has many applications. Typical hardware options for performing DSP are field-programmable gate arrays (FPGAs), application-specific integrated DSP chips, or general purpose personal computer systems. This paper presents a novel DSP platform that has been developed for feedback control on the HBT-EP tokamak device. The system runs all signal processing exclusively on a Graphics Processing Unit (GPU) to achieve real-time performance with latencies below 8 μs. Signals are transferred into and out of the GPU using PCI Express peer-to-peer direct-memory-access transfers without involvement of the central processing unit or host memory. Tests were performed on the feedback control system of the HBT-EP tokamak using forty 16-bit floating point inputs and outputs each and a sampling rate of up to 250 kHz. Signals were digitized by a D-TACQ ACQ196 module, processing done on an NVIDIA GTX 580 GPU programmed in CUDA, and analog output was generated by D-TACQ AO32CPCI modules.
Fiber-optic thermometry using thermal radiation from Tm end doped SiO2 fiber sensor
Authors: Morita Kentaro , Katsumata Toru , Komuro Shuji , Aizawa Hiroaki
Published: April 2014

Fiber-optic thermometry based on temperature dependence of thermal radiation from Tm3+ ions was studied using Tm end doped SiO2 fiber sensor. Visible light radiation peaks due to f-f transition of Tm3+ ion were clearly observed at λ = 690 and 790 nm from Tm end doped SiO2 fibers sensor at the temperature above 600 °C. Thermal radiation peaks are assigned with f-f transition of Tm3+ ion, 1D2-3H6, and 1G4-3H6. Peak intensity of thermal radiation from Tm3+ ion increases with temperature. Intensity ratio of thermal radiation peaks at λ = 690 nm against that at λ = 790 nm, I790/690, is suitable for the temperature measurement above 750 °C. Two-dimensional temperature distribution in a flame is successfully evaluated by Tm end doped SiO2 fiber sensor.
Accurate non-Born-Oppenheimer calculations of the complete pure vibrational spectrum of ditritium using all-particle explicitly correlated Gaussian functions
Authors: Bubin Sergiy , Stanke Monika , Adamowicz Ludwik
Published: April 2014

Very accurate variational calculations of the complete pure vibrational spectrum of the ditritium (T2) molecule are performed within the framework where the Born-Oppenheimer approximation is not assumed. After separating out the center-of-mass motion from the total laboratory-frame Hamiltonian, T2 becomes a three-particle problem. States corresponding to the zero total angular momentum, which are pure vibrational states, are spherically symmetric in this framework. The wave functions of these states are expanded in terms of all-particle, one-center, spherically symmetric explicitly correlated Gaussian functions multiplied by even non-negative powers of the internuclear distance. In the calculations the total energies, the dissociation energies, and expectation values of some operators dependent on interparticle distances are determined.
Determination of the Eckart molecule-fixed frame by use of the apparatus of quaternion algebra
Authors: Krasnoshchekov Sergey V. , Isayeva Elena V. , Stepanov Nikolay F.
Published: April 2014

The problem of determining the Eckart molecule-fixed frame for an arbitrary molecule with nuclei displaced from the equilibrium positions is considered. The solution of the problem is formulated by minimizing the sum of mass-weighted squared deviations (MWSD) of the nuclei of a displaced configuration from the nuclei of the equilibrium configuration. A mathematical proof of the equivalence of Eckart conditions and the minimum of MWSD is given. It is shown that the extrema of the sum of MWSD coincide with eigenvalues of a special 4 × 4 symmetric matrix. Its minimal eigenvalue corresponds to the desired solution, and the respective eigenvector can be treated as the quaternion containing the necessary information for rotating the original coordinate system and aligning its axes with the molecule-fixed coordinate system. A detailed scheme for an efficient numerical implementation of the method is provided, and a numerical example is given.
Non-destructive testing of composite plates by holographic vibrometry
Authors: Bruno Francois , Laurent Jérôme , Prada Claire , Lamboul Benjamin , Passilly Bruno , Atlan Michael
Published: April 2014

We report on a wide-field optical monitoring method for revealing local delaminations in sandwich-type composite plates at video-rate by holographic vibrometry. Non-contact measurements of low frequency flexural waves is performed with time-averaged heterodyne holography. It enables narrowband imaging of local out-of-plane nanometric vibration amplitudes under sinusoidal excitation and reveals delamination defects, which cause local resonances of flexural waves. The size of the defect can be estimated from the first resonance frequency of the flexural wave and the mechanical parameters of the observed layer of the composite plate.
Phase transformation pathways in amorphous germanium under indentation pressure
Authors: Deshmukh S. , Haberl B. , Ruffell S. , Munroe P. , Williams J. S. , Bradby J. E.
Published: April 2014

Nanoindentation-induced phase transformations have been studied in amorphous Ge thin films. These films initially tend to deform via plastic flow of the amorphous phase under load but at a critical pressure a sudden phase transformation occurs. This transformation, to a soft metallic (β-Sn-like)-Ge phase confined under the indenter, is signified by a “pop-in” event on loading. Following “pop-in,” the indentation tests fall into two distinct types of behavior. In one case, the rate of deformation with increasing load after “pop-in” increases, and the observed end-phase following complete unloading is observed to be predominately diamond-cubic Ge. In the other case, the deformation rate (slope of the loading curve) remains the same as that before “pop-in,” and the end phases following unloading are found to contain predominantly unstable r8 and more stable hexagonal Ge phases. The different transformation pathways for these two cases are shown to be related to the probability that the soft (β-Sn-like)-Ge phase volume, which suddenly forms at the transformation pressure, is either unconstrained by the indenter tip (the first case) or totally constrained under the indenter tip (in the latter case).
Materials properties and dislocation dynamics in InAsP compositionally graded buffers on InP substrates
Authors: Jandl Adam , Bulsara Mayank T. , Fitzgerald Eugene A.
Published: April 2014

The properties of InAsxP1−x compositionally graded buffers grown by metal organic chemical vapor deposition are investigated. We report the effects of strain gradient (ε/thickness), growth temperature, and strain initiation sequence (gradual or abrupt strain introduction) on threading dislocation density, surface roughness, epi-layer relaxation, and tilt. We find that gradual introduction of strain causes increased dislocation densities (>106/cm2) and tilt of the epi-layer (>0.1°). A method of abrupt strain initiation is proposed which can result in dislocation densities as low as 1.01 × 105 cm−2 for films graded from the InP lattice constant to InAs0.15P0.85. A model for a two-energy level dislocation nucleation system is proposed based on our results.
High performance flexible top-emitting warm-white organic light-emitting devices and chromaticity shift mechanism
Authors: Shi Hongying , Deng Lingling , Chen Shufen , Xu Ying , Zhao Xiaofei , Cheng Fan , Huang Wei
Published: April 2014

Flexible warm-white top-emitting organic light-emitting devices (TEOLEDs) are fabricated onto PET substrates with a simple semi-transparent cathode Sm/Ag and two-color phosphors respectively doped into a single host material TCTA. By adjusting the relative position of the orange-red EML sandwiched between the blue emitting layers, the optimized device exhibits the highest power/current efficiency of 8.07 lm/W and near 13 cd/A, with a correlated color temperature (CCT) of 4105 K and a color rendering index (CRI) of 70. In addition, a moderate chromaticity variation of (-0.025, +0.008) around warm white illumination coordinates (0.45, 0.44) is obtained over a large luminance range of 1000 to 10000 cd/m2. The emission mechanism is discussed via delta-doping method and single-carrier device, which is summarized that the carrier trapping, the exciton quenching, the mobility change and the recombination zone alteration are negative to color stability while the energy transfer process and the blue/red/blue sandwiched structure are contributed to the color stability in our flexible white TEOLEDs.
Sphere-plate Casimir interaction in
(D + 1)
-dimensional spacetime
Authors: Teo L. P.
Published: April 2014

In this paper, we derive the formula for the Casimir interaction energy between a sphere and a plate in (D + 1)-dimensional Minkowski spacetime. It is assumed that the scalar field satisfies the Dirichlet or Neumann boundary conditions on the sphere and the plate. As in the D = 3 case, the formula is of TGTG type. One of our main contributions is deriving the translation matrices which express the change of bases between plane waves and spherical waves for general D. Using orthogonality of Gegenbauer polynomials, it turns out that the final TGTG formula for the Casimir interaction energy can be simplified to one that is similar to the D = 3 case. To illustrate the application of the formula, both large separation and small separation asymptotic behaviors of the Casimir interaction energy are computed. The large separation leading term is proportional to L−D+1 if the sphere is imposed with Dirichlet boundary condition, and to L−D−1 if the sphere is imposed with Neumann boundary condition, where L is distance from the center of the sphere to the plane. For the small separation asymptotic behavior, it is shown that the leading term is equal to the one obtained using proximity force approximation. The next-to-leading order term is also computed using perturbation method. It is shown that when the space dimension D is larger than 5, the next-to-leading order has sign opposite to the leading order term. Moreover, the ratio of the next-to-leading order term to the leading order term is linear in D, indicating a larger correction at higher dimensions.
Influence of Xe2+ ions on the micro-hollow cathode discharge driven by thermionic emission
Authors: Levko D. , Bliokh Y. P. , Krasik Ya. E.
Published: April 2014

The influence of Xe2+ dimer ions and excited Xe* atoms on the hollow cathode discharge driven by electron thermionic emission is studied using two-dimensional Particle-in-Cell Monte Carlo Collisions modeling. A comparison with the results of two-component (electrons and Xe+ ions) plasma modeling showed that the presence of the Xe2+ dimer ions and excited Xe* atoms in the plasma affects the plasma parameters (density, potential, and ion fluxes toward the cathode). The influence of Xe2+ ions and Xe* atoms on the plasma sheath parameters, such as thickness and the ion velocity at the sheath edge, is analyzed.
Collisional relaxation of a strongly magnetized two-species pure ion plasma
Authors: Chim Chi Yung , O’Neil Thomas M. , Dubin Daniel H.
Published: April 2014

The collisional relaxation of a strongly magnetized pure ion plasma that is composed of two species with slightly different masses is discussed. We have in mind two isotopes of the same singly ionized atom. Parameters are assumed to be ordered as Ω1,Ω2≫|Ω1−Ω2|≫v¯ij/b¯ and v¯⊥j/Ωj≪b¯, where Ω1 and Ω2 are two cyclotron frequencies, v¯ij=T∥/μij is the relative parallel thermal velocity characterizing collisions between particles of species i and j, and b¯=2e2/T∥ is the classical distance of closest approach for such collisions, and v¯⊥j/Ωj=2T⊥j/mj/Ωj is the characteristic cyclotron radius for particles of species j. Here, μij is the reduced mass for the two particles, and T∥ and T⊥j are temperatures that characterize velocity components parallel and perpendicular to the magnetic field. For this ordering, the total cyclotron action for the two species, I1=∑i∈1m1v⊥i2/(2Ω1) and I2=∑i∈2m2v⊥i2/(2Ω2) are adiabatic invariants that constrain the collisional dynamics. On the timescale of a few collisions, entropy is maximized subject to the constancy of the total Hamiltonian H and the two actions I1 and I2, yielding a modified Gibbs distribution of the form exp[−H/T∥−α1I1−α2I2]. Here, the αj’s are related to T∥ and T⊥j through T⊥j=(1/T∥+αj/Ωj)−1. Collisional relaxation to the usual Gibbs distribution, exp[−H/T∥], takes place on two timescales. On a timescale longer than the collisional timescale by a factor of (b¯2Ω12/v¯112)exp{5[3π(b¯|Ω1−Ω2|/v¯12)]2/5/6}, the two species share action so that α1 and α2 relax to a common value α. On an even longer timescale, longer than the collisional timescale by a factor of the order exp{5[3π(b¯Ω1/v¯11)]2/5/6}, the total action ceases to be a good constant of the motion and α relaxes to zero.
Irradiation-induced nano-voids in strained tin precipitates in silicon
Authors: Gaiduk P. I. , Lundsgaard Hansen J. , Nylandsted Larsen A.
Published: April 2014

We report on self-assembling of spherically shaped voids in nanometer size strained Sn precipitates after irradiation with He+ ions in different conditions. It is found that high-temperature irradiation induces vacancies which are collected by compressively strained Sn precipitates enhancing of out-diffusion of Sn atoms from the precipitates. Nano-voids formation takes place simultaneously with a β- to α-phase transformation in the Sn precipitates. Post-irradiation thermal treatment leads to the removal of voids and a backward transformation of the Sn phase to β-phase. Strain-enhanced separation of point defects along with vacancy assisted Sn out-diffusion and precipitate dissolution are discussed.
Experimental and theoretical demonstration of acoustic Bloch oscillations in porous silicon structures
Authors: Lazcano Z. , Arriaga J. , Aliev G. N.
Published: April 2014

We report the theoretical calculations and the experimental demonstration of acoustic Bloch oscillations and Wannier-Stark ladders in linear tilted multilayer structures based on porous silicon. The considered structures consist of layers with constant porosity alternated by layers with a linear gradient in the parameter η=1/vL2 along the growth direction in order to tilt the acoustic band gap. The purpose of this gradient is to mimic the tilted electronic miniband structure of a superlattice semiconductor under an external electric field. In this way, acoustic Wannier-Stark ladders of equidistant modes are formed and they were experimentally confirmed in the transmission spectrum around 1.2 GHz. Their frequency separation defines the period of the acoustic Bloch oscillations. We fabricated three different structures with the same thicknesses but different values in the η parameter to observe the effect on the period of the Bloch oscillations. We measured the acoustic transmission spectra in the frequency domain, and by using the Fourier transform, we obtained the transmission in the time domain. The transmission spectra of the fabricated samples show acoustic Bloch oscillations with periods of 27, 24, and 19 ns. The experimental results are in good agreement with the transfer matrix calculations. The observed phenomenon is the acoustic counterpart of the well known electronic Bloch oscillations.
Effect of the VAsVGa complex defect doping on properties of the semi-insulating GaAs
Authors: Ma Deming , Qiao Hongbo , Shi Wei , Li Enling
Published: April 2014

The different position VAsVGa cluster defect doping in semi-insulating (SI) GaAs has been studied by first-principles calculation based on hybrid density functional theory. Our calculated results show that EL6 level is formed due to the VAsVGa complex defect, which is very close to the experimental result. It provides the explanation of the absorption of laser with the wavelength beyond in semi-insulating GaAs. The formation energy of VAsVGa complex defect is found to decrease from surface to interior gradually. The conduction band minima and valence band maxima of GaAs (001) surface with the VAsVGa complex defect are all located at Γ point, and some defect levels are produced in the forbidden band. In contrast, the conduction band minima and valence band maxima of GaAs with the interior VAsVGa complex defect are not located at the same k-point, so it might involve the change of momentum in the electron transition process. The research will help strengthen the understanding of photoelectronic properties and effectively guide the preparation of the SI-GaAs materials.
Photonic nano-structures on (111)-oriented diamond
Authors: Neu Elke , Appel Patrick , Ganzhorn Marc , Miguel-Sánchez Javier , Lesik Margarita , Mille Vianney , Jacques Vincent , Tallaire Alexandre , Achard Jocelyn , Maletinsky Patrick
Published: April 2014

We demonstrate the fabrication of single-crystalline diamond nanopillars on a (111)-oriented chemical vapor deposited diamond substrate. This crystal orientation offers optimal coupling of nitrogen-vacancy (NV) center emission to the nanopillar mode and is thus advantageous over previous approaches. We characterize single native NV centers in these nanopillars and find one of the highest reported saturated fluorescence count rates in single crystalline diamond in excess of 106 counts per second. We show that our nano-fabrication procedure conserves the preferential alignment as well as the spin coherence of the NVs in our structures. Our results will enable a new generation of highly sensitive probes for NV magnetometry and pave the way toward photonic crystals with optimal orientation of the NV center's emission dipole.
DNA translocation through short nanofluidic channels under asymmetric pulsed electric field
Authors: Gupta C. , Liao W.-C. , Gallego-Perez D. , Castro C. E. , Lee L. J.
Published: April 2014

Investigation of single molecule DNA dynamics in confined environments has led to important applications in DNA analysis, separation, and sequencing. Here, we studied the electrophoretic transport of DNA molecules through nanochannels shorter than the DNA contour length and calculated the associated translocation time curves. We found that the longer T4 DNA molecules required a longer time to traverse a fixed length nanochannel than shorter λ DNA molecules and that the translocation time decreased with increasing electric field which agreed with theoretical predictions. We applied this knowledge to design an asymmetric electric pulse and demonstrate the different responses of λ and T4 DNA to the pulses. We used Brownian dynamics simulations to corroborate our experimental results on DNA translocation behaviour. This work contributes to the fundamental understanding of polymer transport through nanochannels and may help in designing better separation techniques in the future.
Organic light-emitting diodes with a spacer enhanced exciplex emission
Authors: Yan Fei , Chen Rui , Sun Handong , Wei Sun Xiao
Published: April 2014

By introducing a spacer molecule into the blended exciplex emissive layer, the performance of the bulk heterojunction exciplex organic light-emitting diodes (OLEDs) was improved dramatically; the maximum luminous efficiency was enhanced by about 22% from 7.9 cd/A to 9.7 cd/A, and the luminous efficiency drop was reduced by 28% at 400 mA/cm2. Besides the suppressed annihilation of exciton, the time-resolved photoluminescence measurements indicated that the spacer enhanced the delayed fluorescence through increasing the backward intersystem crossing rate from the triplet to singlet exciplex state. This method is useful for developing high performance exciplex OLEDs.
Perpendicular exchange bias effect in sputter-deposited CoFe/IrMn bilayers
Authors: Chen J. Y. , Thiyagarajah Naganivetha , Xu H. J. , Coey J. M. D.
Published: April 2014

CoFe/IrMn bilayers with perpendicular magnetization for various IrMn layer thicknesses exhibit unusual two-step hysteresis loops with both positive and negative loop shifts. Observed at room temperature in the as-grown state, they provide direct evidence of large antiferromagnetic domain formation at the IrMn interface. The exchange bias field reaches 100 mT with an IrMn layer thickness of 4 nm after field annealing at 200 °C–300 °C in 800 mT, which is at least three times as large as the coercivity, and may be useful for reference layers of spin-valves or magnetic tunnel junctions with perpendicular magnetic anisotropy.
Organic integrated circuits for information storage based on ambipolar polymers and charge injection engineering
Authors: Dell'Erba Giorgio , Luzio Alessandro , Natali Dario , Kim Juhwan , Khim Dongyoon , Kim Dong-Yu , Noh Yong-Young , Caironi Mario
Published: April 2014

Ambipolar semiconducting polymers, characterized by both high electron (μe) and hole (μh) mobility, offer the advantage of realizing complex complementary electronic circuits with a single semiconducting layer, deposited by simple coating techniques. However, to achieve complementarity, one of the two conduction paths in transistors has to be suppressed, resulting in unipolar devices. Here, we adopt charge injection engineering through a specific interlayer in order to tune injection into frontier energy orbitals of a high mobility donor-acceptor co-polymer. Starting from field-effect transistors with Au contacts, showing a p-type unbalanced behaviour with μh = 0.29 cm2/V s and μe = 0.001 cm2/V s, through the insertion of a caesium salt interlayer with optimized thickness, we obtain an n-type unbalanced transistor with μe = 0.12 cm2/V s and μh = 8 × 10−4 cm2/V s. We applied this result to the development of the basic pass-transistor logic building blocks such as inverters, with high gain and good noise margin, and transmission-gates. In addition, we developed and characterized information storage circuits like D-Latches and D-Flip-Flops consisting of 16 transistors, demonstrating both their static and dynamic performances and thus the suitability of this technology for more complex circuits such as display addressing logic.
Electric field induced transformation of carbon nanotube to graphene nanoribbons using Nafion as a solid polymer electrolyte
Authors: Jaison M. J. , Vikram K. , Narayanan Tharangattu N. , Pillai Vijayamohanan K.
Published: April 2014

We report a remarkable transformation of multiwalled carbon nanotubes (MWCNTs, average diameter 40 nm) to graphene nanoribbons (GNRs) in response to a field gradient of ∼25 V/cm, in a sandwich configuration using a solid state proton conducting polymer electrolyte like a thin perfluorosulphonated membrane, Nafion. In response to the application of a constant voltage for a sustained period of about 24 h at both room temperature and elevated temperatures, an interesting transformation of MWCNTs to GNRs has been observed with reasonable yield. GNRs prepared by this way are believed to be better for energy storage applications due to their enhanced surface area with more active smooth edge planes. Moreover, possible morphological changes in CNTs under electric field can impact on the performance and long term stability of devices that use CNTs in their electronic circuitry.
Zinc vacancy and erbium cluster jointly promote ferromagnetism in erbium-doped ZnO thin film
Authors: Chen Hong-Ming , Liu Xue-Chao , Zhuo Shi-Yi , Xiong Ze , Zhou Ren-Wei , Li Fei , Shi Er-Wei
Published: April 2014

Zn1-xErxO (0.005 ≤ x ≤ 0.04) thin films have been prepared by inductively coupled plasma enhanced physical vapor deposition method. Ferromagnetism, crystal structure, microstructure and photoluminescence properties of the films were characterized. It is found that the chemical valence state of Er is trivalent, and the Er3+ cations play an important role in ferromagnetism. Both saturated magnetization (Ms) and zinc vacancy (VZn) are decreased with the increase of x from 0.005 to 0.03. However, further increasing x to 0.04, the Ms is quenched due to the generation of Er clusters. It reveals that the intensity of Ms is not only associated with the VZn concentration, but also related to the Er clusters. The VZn concentration and the Er clusters can jointly boost the ferromagnetism in the Zn1-xErxO thin films.
Growth kinetics engineered magnetoresistance response in La2/3Sr1/3MnO3 thin films
Authors: Pomar A. , Santiso J. , Sandiumenge F. , Roqueta J. , Bozzo B. , Frontera C. , Balcells Ll. , Martínez B. , Konstantinović Z.
Published: April 2014

A route to engineer the intrinsic colossal magnetoresistance (CMR) response in manganite thin films through an accurate control of the growth kinetics is presented. It is shown that under specific growth conditions, a particular strained state, substantially different from that of bulk-like materials and standard films, can be quenched up to film thicknesses around 60 nm. This strained state exhibits the same structural fingerprints of the interfacial dead layer in standard films and promotes surface morphology instabilities, which end up with the formation of self-organized nanopits array. At the same time, it has profound effects on the intrinsic magnetoelectronic properties of the films that exhibit an enhanced intrinsic CMR response.
Surface wave patterns on acoustically levitated viscous liquid alloys
Authors: Hong Z. Y. , Yan N. , Geng D. L. , Wei B.
Published: April 2014

We demonstrate two different kinds of surface wave patterns on viscous liquid alloys, which are melted and solidified under acoustic levitation condition. These patterns are consistent with the morphologies of standing capillary waves and ensembles of oscillons, respectively. The rapid solidification of two-dimensional liquid alloy surfaces may hold them down.
Reproductive development of four top flowering annual clovers
Authors: Nori H. , Moot D. J. , Monks D. P. , Black A. D. , Lucas R. J.
Published: April 2014

A series of field experiments aimed to quantify reproductive development of four clover species, arrowleaf (Trifolium vesiculosum), balansa (T. michelianum), gland (T. glanduliferum) and Persian (T. resupinatum), for introduction to New Zealand dryland pastures. The duration from emergence to flowering was related to the length of, and direction of change in, photoperiod at the time of first trifoliate leaf appearance. Autumn-sown crops that emerged into a decreasing photoperiod had a longer vegetative growth before they turned reproductive. The time to flower became shorter with increasing photoperiod until the longest day of the year, before it began to slow down as photoperiod decreased towards late summer. Prima gland clover flowered earlier (500–1216 degree-days) than Bolta balansa (600–1733 degree-days), Cefalu arrowleaf (940–1834 degree-days) and Mihi Persian (1047–2610 degree-days) clovers. The duration from pollination to physiological maturity was 274–689 degree-days for Cefalu, 185 degree-days for Bolta, 256 degree-days for Prima, and 425 degree-days for Mihi. The differences in flowering time suggests the suitability of Prima gland clover for areas that dry out quickly in late spring, Bolta balansa clover for areas of wet winter and dry summer, and Cefalu arrowleaf and Mihi Persian clovers for areas that receive higher spring rainfall.
Reflections on the framing of ‘health equity’ in the National Primary Health Care Strategic Framework: a cause for celebration or concern?
Authors: Smith James A.
Published: April 2014

Issue addressed

There has been a growing national and global focus on the need to address social determinants of health to better achieve equitable health outcomes. In Australia, this focus is now being embedded into state, territory and Commonwealth government health policies. In this paper I use the National Primary Health Care Strategic Framework as a case study to examine the way in which ‘health equity’ and other related terms have been framed within a current national health policy context.

Discussion

Using a critically reflective approach, I argue that primary health care and health promotion professionals need to capitalise on the inclusion of terms such as ‘action on social determinants of health’, ‘health equity’ and ‘reducing inequity’ through emerging national health policies, such as the National Primary Health Care Strategic Framework. Yet, there is also a need to proceed with caution. The way in which these terms are framed appears to deviate from the principles, values and ideologies on which they are historically based. The implications for contemporary health promotion practice in Australia are discussed.

Conclusions

Primary health care and health promotion professionals working in both policy and practice contexts are encouraged to engage in critical reflective practice when interpreting and considering the implementation requirements of national health policies that incorporate a health equity focus.

So what?

To build health equity in Australia, primary health care and health promotion professionals will be required to engage in the skilful reframing of current primary health care policy discourses relating to health equity during health promotion planning, implementation and evaluation processes.
From evidence to action: health promotion and alcohol
Authors: Stafford Julia , Allsop Steve , Daube Mike
Published: April 2014

Preventing alcohol‐related harm presents a range of challenges including those related to political will, competing interests with disproportionate resources, and embedded drinking cultures. On the other hand there are opportunities for health promotion, including clear evidence on both the extent of the problem and evidence‐based responses and growing community support for action. Australian researchers continue to contribute substantially to the international evidence base on alcohol, generating evidence for translation into effective programs and producing policy‐relevant research on which action and advocacy can be based. Successes in other public health areas also provide useful models for public health approaches to alcohol. Those engaged in health promotion have often been required to do a lot with a little, including communicating health messages on a range of themes, countering industry activities that are contrary to good public health and involvement in policy development. Coalition approaches to alcohol related harm, including links with groups outside health, have recently gained momentum and show much potential. Alcohol issues are now firmly on the agenda of the public and decision‐makers, and the alcohol industry has expressed clear concern at current levels of activity. This paper will consider briefly the nature of the challenge; evidencebased approaches; achievements and developments thus far; challenges and obstacles; and the role of health promotion and the health promotion workforce.
Domain within the helicase subunit Mcm4 integrates multiple kinase signals to control DNA replication initiation and fork progression
Authors: Sheu Yi-Jun , Kinney Justin B. , Lengronne Armelle , Pasero Philippe , Stillman Bruce
Published: April 2014

Significance

During each cell-division cycle, eukaryotic cells initiate DNA synthesis from multiple replication origins on chromosomes to duplicate the entire genome once and only once. Spatial and temporal control of initiation and subsequent DNA synthesis at replication forks is important for maintaining genome integrity. Here we present a comprehensive analysis of patterns of origin activation, replication fork progression, and checkpoint responses in cells under replication stress. Our studies showed that a domain intrinsic to the replicative helicase, which unwinds DNA during replication, integrates multiple kinase-signaling pathways to control various aspects of the genome duplication process. Our work suggests a mechanism by which eukaryotic cells modulate the pattern of replication in response to environmental conditions through the replicative helicase.
Inhibitory effects of the κ-casein macropeptide isolated from milk protein on the biofilm formation and virulence of Listeria monocytogenes
Authors: Yun Hyun Sun , Kim Younghoon , Park Mi Ri , Kim Sae Hun , Oh Sejong
Published: April 2014

We demonstrate the inhibitory effects of κ-casein macropeptide (CMP) on the biofilm formation and virulence of Listeria monocytogenes Scott A. The inhibition of biofilm formation by CMP was initially investigated by using the protocol applied for the 96-well microtiter plate assay. Low concentrations of CMP (0.1, 0.2, 0.3, 0.4, and 0.5 mg/mL) that were tested resulted in a profound inhibitory effect on biofilm formation at a concentration of 0.4 mg/mL. CMP also significantly repressed the transcription of inlA (encoding internalin A) that was responsible for the initial adhesion and invasion event, and prolonged the survival of Caenorhabditis elegans infected by L. monocytogenes. Two-dimensional gel electrophoresis showed that newly identified proteins in the presence of CMP were involved in the stress response and metabolic processes that have important roles in developing listerial biofilms. Our results suggest that CMP from milk protein would be capable of eliminating biofilm formation and virulence by L. monocytogenes in the food industry.
Inferring rare disease risk variants based on exact probabilities of sharing by multiple affected relatives
Authors: Bureau Alexandre , Younkin Samuel G. , Parker Margaret M. , Bailey-Wilson Joan E. , Marazita Mary L. , Murray Jeffrey C. , Mangold Elisabeth , Albacha-Hejazi Hasan , Beaty Terri H. , Ruczinski Ingo
Published: April 2014

Motivation: Family-based designs are regaining popularity for genomic sequencing studies because they provide a way to test cosegregation with disease of variants that are too rare in the population to be tested individually in a conventional case–control study.

Results: Where only a few affected subjects per family are sequenced, the probability that any variant would be shared by all affected relatives—given it occurred in any one family member—provides evidence against the null hypothesis of a complete absence of linkage and association. A P -value can be obtained as the sum of the probabilities of sharing events as (or more) extreme in one or more families. We generalize an existing closed-form expression for exact sharing probabilities to more than two relatives per family. When pedigree founders are related, we show that an approximation of sharing probabilities based on empirical estimates of kinship among founders obtained from genome-wide marker data is accurate for low levels of kinship. We also propose a more generally applicable approach based on Monte Carlo simulations. We applied this method to a study of 55 multiplex families with apparent non-syndromic forms of oral clefts from four distinct populations, with whole exome sequences available for two or three affected members per family. The rare single nucleotide variant rs149253049 in ADAMTS9 shared by affected relatives in three Indian families achieved significance after correcting for multiple comparisons ( p=2×10−6 ).

Availability and implementation: Source code and binaries of the R package RVsharing are freely available for download at http://cran.r-project.org/web/packages/RVsharing/index.html .

Contact:  alexandre.bureau@msp.ulaval.ca or ingo@jhu.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.