bluuebunny/crossref_metadata_2025 huggingface dataset:
Relative validity of an FFQ to estimate daily food and nutrient intakes for Chilean adults
Authors: Dehghan Mahshid , Martinez Solange , Zhang Xiaohe , Seron Pamela , Lanas Fernando , Islam Shofiqul , Merchant Anwar T
Published: September 2012

Objective

FFQ are commonly used to rank individuals by their food and nutrient intakes in large epidemiological studies. The purpose of the present study was to develop and validate an FFQ to rank individuals participating in an ongoing Prospective Urban and Rural Epidemiological (PURE) study in Chile.

Design

An FFQ and four 24 h dietary recalls were completed over 1 year. Pearson correlation coefficients, energy-adjusted and de-attenuated correlations and weighted kappa were computed between the dietary recalls and the FFQ. The level of agreement between the two dietary assessment methods was evaluated by Bland–Altman analysis.

Setting

Temuco, Chile.

Subjects

Overall, 166 women and men enrolled in the present study. One hundred men and women participated in FFQ development and sixty-six individuals participated in FFQ validation.

Results

The FFQ consisted of 109 food items. For nutrients, the crude correlation coefficients between the dietary recalls and FFQ varied from 0·14 (protein) to 0·44 (fat). Energy adjustment and de-attenuation improved correlation coefficients and almost all correlation coefficients exceeded 0·40. Similar correlation coefficients were observed for food groups; the highest de-attenuated energy-adjusted correlation coefficient was found for margarine and butter (0·75) and the lowest for potatoes (0·12).

Conclusions

The FFQ showed moderate to high agreement for most nutrients and food groups, and can be used to rank individuals based on energy, nutrient and food intakes. The validation study was conducted in a unique setting and indicated that the tool is valid for use by adults in Chile.
Poor Mothers and Lonely Single Males: The ‘Essentially’ Excluded Women and Men of Australia
Authors: Patulny Roger , Wong Melissa
Published: September 2012

It is unclear how much gendered social exclusion and disconnection reflects a problem or a preference. Women may prefer market-disengagement despite the risk of exclusion from ‘normal’ social activities through financial incapacity, and men may prefer market-engagement despite the risk of disconnection from informal social networks. This article examines these issues amongst Australian men and women. It finds women, particularly single and low-income mothers, are more socially excluded, and men, particularly single middle-aged men, are the most socially disconnected, after preferences. Future policy should be cognisant of contact preferences, intra-household support dynamics, long work hours and prevailing gender norms.
Do psychiatric units at general hospitals attract less stigmatizing attitudes compared with psychiatric hospitals?
Authors: Schomerus G. , Matschinger H. , Angermeyer M.C.
Published: September 2012

Aims.

It is often assumed that psychiatric units at general hospitals attract less stigma than do specialized psychiatric hospitals, but so far this has not been examined empirically.

Methods.

We conducted a representative population survey in Germany (n = 2410) in order to compare attitudes towards psychiatric units and attitudes towards psychiatric hospitals. Two subsamples were presented with identical items concerning either psychiatric units or hospitals. We conducted multinomial logit analyses of answer categories to detect any differences in attitudes.

Results.

A majority of respondents held favourable opinions of psychiatric in-patient care at both psychiatric units and psychiatric hospitals. Attitudes towards units and hospitals did not differ meaningfully.

Conclusions.

The influence of location on the image of psychiatric care has been over-estimated. We discuss other implications of locating psychiatric care at general hospitals.
An analytic criterion for generalized synchronization in unidirectionally coupled systems based on the auxiliary system approach
Authors: Wong W. K. , Zhen Bin , Xu Jian , Wang Zhijie
Published: September 2012

An analytic criterion is developed to investigate generalized synchronization (GS) in unidirectionally coupled systems based on the auxiliary system approach. The criterion is derived by transforming the existence problem of generalized synchronization into an eigenvalue problem. Numerical simulations show that the analytic criterion is almost as accurate as the response Lyapunov exponents method, and may provide an estimation of the threshold of strong generalized synchronization. A significant result can be deduced from our analysis that the more the number of equilibria of the unidirectionally coupled systems, the greater the chance of generalized synchronization, but the harder it may be for strong generalized synchronization to occur.
Van der Waals interactions between hydrocarbon molecules and zeolites: Periodic calculations at different levels of theory, from density functional theory to the random phase approximation and Møller-Plesset perturbation theory
Authors: Göltl Florian , Grüneis Andreas , Bučko Tomas , Hafner Jürgen
Published: September 2012

The adsorption of small alkane molecules in purely siliceous and protonated chabazite has been investigated at different levels of theory: (i) density-functional (DFT) calculations with a gradient-corrected exchange-correlation functional; DFT calculations using the Perdew-Burke-Ernzerhof (PBE) functional with corrections for the missing dispersion forces in the form of C6/R6 pair potentials with (ii) C6 parameters and vdW radii determined by fitting accurate energies for a large molecular data base (PBE−d) or (iii) derived from “atoms in a solid” calculations; (iv) DFT calculations using a non-local correlation functional constructed such as to account for dispersion forces (vdW-DF); (v) calculations based on the random phase approximation (RPA) combined with the adiabatic-coupling fluctuation-dissipation theorem; and (vi) using Hartree-Fock (HF) calculations together with correlation energies calculated using second-order Møller-Plesset (MP2) perturbation theory. All calculations have been performed for periodic models of the zeolite and using a plane-wave basis and the projector-augmented wave method. The simpler and computationally less demanding approaches (i)–(iv) permit a calculation of the forces acting on the atoms using the Hellmann-Feynman theorem and further a structural optimization of the adsorbate-zeolite complex, while RPA and MP2 calculations can be performed only for a fixed geometry optimized at a lower level of theory. The influence of elevated temperature has been taken into account by averaging the adsorption energies calculated for purely siliceous and protonated chabazite, with weighting factors determined by molecular dynamics calculations with dispersion-corrected forces from DFT. Compared to experiment, the RPA underestimates the adsorption energies by about 5 kJ/mol while MP2 leads to an overestimation by about 6 kJ/Mol (averaged over methane, ethane, and propane). The most accurate results have been found for the “hybrid” RPA-HF method with an average error of less than 2 kJ/mol only, while RPA underestimates the adsorption energies by about 8 kJ/mol on average. MP2 overestimates the adsorption energies slightly, with an average error of 5 kJ/mol. The more approximate and computationally less demanding methods such as the vdW-DF density functional or the C6/R6 pair potentials with C6 parameters from “atoms in a solid” calculations overestimate the adsorption energies quite strongly. Relatively good agreement with experiment is achieved with the empirical PBE+d method with an average error of about 5 kJ/mol.
Investigation of defect levels in Cs2Hg6S7 single crystals by photoconductivity and photoluminescence spectroscopies
Authors: Peters J. A. , Cho Nam Ki , Liu Zhifu , Wessels B. W. , Li Hao , Androulakis J. , Kanatzidis M. G.
Published: September 2012

The heavy element semiconductor compound Cs2Hg6S7 is of interest as a potential wide gap semiconductor for gamma ray detection. To determine electrically active defects and their energy levels, photoconductivity (PC) spectroscopy was carried out over the temperature range of 90-295 K. The low temperature spectrum exhibits photoconductive transitions at 1.495, 1.61, 1.66, and 1.68 eV. The optical transitions are tentatively attributed to defects with levels located at energies of 50, 70, 120, and 240 meV from the band edge. A superlinear dependence of photocurrent on illumination intensity is observed that is attributed to a two-center recombination process that involves shallow traps and recombination centers. Near band edge photoluminescence (PL) was observed over the temperature range of 24–80 K. The spectrum revealed three defect related emission bands located at 1.68, 1.66, and 1.62 eV, whose ionization energies are 57 meV, 78 meV, and 115 meV, respectively. From the temperature and excitation dependencies of the observed peak intensities and energies, the radiative recombination mechanisms of the bands were attributed to transitions involving excitons bound to neutral and ionized acceptors. Good agreement of the defect level energies determined by PL and PC were noted, indicating that they were of the same origin. The defects were tentatively attributed to metal vacancies that form shallow acceptor levels.
Silicide-phase evolution and platinum redistribution during silicidation of Ni0.95Pt0.05/Si(100) specimens
Authors: Adusumilli Praneet , Seidman David N. , Murray Conal E.
Published: September 2012

We investigated the temporal evolution of nickel-silicide phase-formation and the simultaneous redistribution of platinum during silicidation of a 10 nm thick Ni0.95Pt0.05 film on a Si(100) substrate. Grazing incidence x-ray diffraction (GIXRD) and atom-probe tomography (APT) measurements were performed on as-deposited films and after rapid thermal annealing (RTA) at 320 or 420 °C for different times. Observation of the Ni2Si phase in as-deposited films, both with and without platinum alloying, is attributed to surface preparation. RTA at 320 °C for 5 s results in the formation of the low-resistivity NiSi intermetallic phase and nickel-rich phases, Ni2Si and Ni3Si2, as demonstrated by GIXRD measurements. At 420 °C for 5 s, the NiSi phase grows outward from the silicide/Si(100) interface by consuming the nickel-rich silicide phases. On increasing the annealing time at 420 °C to 30 min, this reaction is driven towards completion. The nickel-silicide/silicon interface is reconstructed in three-dimensions employing APT and its chemical root-mean-square roughness, based on a silicon isoconcentration surface, decreases to 0.6 nm with the formation of the NiSi phase during silicidation. Pt redistribution is affected by the simultaneous reaction between Ni and Si during silicidation, and it influences the resulting microstructure and thermal stability of the NiSi phase. Short-circuit diffusion of Pt via grain boundaries in NiSi is observed, which affects the resultant grain size, morphology, and possibly the preferred orientation of the NiSi grains. Pt segregates at the NiSi/Si(100) heterophase interface and may be responsible for the morphological stabilization of NiSi against agglomeration to temperatures greater than 650 °C. The Gibbsian interfacial excess of Pt at the NiSi/Si(100) interface after RTA at 420 °C for 5 s is 1.2 ± 0.01 atoms nm−2 and then increases to 2.1 ± 0.02 atoms nm−2 after 30 min at 420 °C, corresponding to a decrease in the interfacial free energy of 7.1 mJ m−2.
Phase coexistence evolution of nano BaTiO3 as function of particle sizes and temperatures
Authors: Zhu Jinlong , Han Wei , Zhang Hui , Yuan Zhen , Wang Xiaohui , Li Longtu , Jin Changqin
Published: September 2012

Using high resolution synchrotron x-ray diffraction, we systemically study the crystal structure evolution of nano BaTiO3 as function of temperatures and particle sizes. In the temperature range from 200 K to 450 K, the nano BaTiO3 with different particles in the range from 5 nm to 100 nm are phase coexisting. The phase fraction evolutions of different nano BaTiO3 indicated that there is an anomaly at particle size around 20 nm, a phase reentrance taking place. The competition of the shear stresses and the compressive stresses on the particle surface, and the delicate balance between them are responsible for the reentrance phenomenon.
New simulation approach using classical formalism to water nuclear magnetic relaxation dispersions in presence of superparamagnetic particles used as MRI contrast agents
Authors: Vuong Q. L. , Gossuin Y. , Gillis P. , Delangre S.
Published: September 2012

Superparamagnetic nanoparticles are used as negative contrast agents in magnetic resonance imaging: owing to their large magnetic moment the water proton spins are dephased, which accelerates the nuclear magnetic relaxation of an aqueous sample containing these particles. Transverse and longitudinal relaxation times depend on several parameters of the nanoparticles such as radius and magnetization and on experimental parameters such as the static magnetic field or echo time. In this work, we introduce a new simulation methodology, using a classical formalism, allowing the simulation of the NMR signal during transverse and longitudinal relaxation induced by superparamagnetic particles in an aqueous solution, which, to our knowledge has never been done before. Nuclear magnetic relaxation dispersion profiles are obtained for a wide range of nanoparticle radii and magnetizations. The results can be classified in two regimes—the well-known motional averaging and static regimes. This generalizes previous studies focusing on transverse relaxation at high magnetic field (larger than 1 T). Simulation results correspond to analytical theories in their validity range and so far unknown dependences of the relaxation with magnetization and radii of the NMR dispersions profiles are observed, which could be used to characterize experimental samples containing large superparamagnetic particles.
Vibrational solvatochromism and electrochromism. II. Multipole analysis
Authors: Lee Hochan , Choi Jun-Ho , Cho Minhaeng
Published: September 2012

Small infrared probe molecules have been widely used to study local electrostatic environment in solutions and proteins. Using a variety of time- and frequency-resolved vibrational spectroscopic methods, one can accurately measure the solvation-induced vibrational frequency shifts and the timescales and amplitudes of frequency fluctuations of such IR probes. Since the corresponding frequency shifts are directly related to the local electric field and its spatial derivatives of the surrounding solvent molecules or amino acids in proteins, one can extract information on local electric field around an IR probe directly from the vibrational spectroscopic results. Here, we show that, carrying out a multipole analysis of the solvatochromic frequency shift, the solvatochromic dipole contribution to the frequency shift is not always the dominant factor. In the cases of the nitrile-, thiocyanato-, and azido-derivatized molecules, the solvatochromic quadrupole contributions to the corresponding stretch mode frequency shifts are particularly large and often comparable to the solvatochromic dipole contributions. Noting that the higher multipole moment-solvent electric field interactions are short range effects in comparison to the dipole interaction, the H-bonding interaction-induced vibrational frequency shift can be caused by such short-range multipole-field interaction effects. We anticipate that the present multipole analysis method specifically developed to describe the solvatochromic vibrational frequency shifts will be useful to understand the intermolecular interaction-induced vibrational property changes and to find out a relationship between vibrational solvatochromism and electrochromism of IR probes in condensed phases.
Bulk universality of general β-ensembles with non-convex potential
Authors: Bourgade Paul , Erdős László , Yau Horng-Tzer
Published: September 2012

We prove the bulk universality of the β-ensembles with non-convex regular analytic potentials for any β > 0. This removes the convexity assumption appeared in the earlier work [P. Bourgade, L. Erdös, and H.-T. Yau, Universality of general β-ensembles, preprint arXiv:0907.5605 (2011)]. The convexity condition enabled us to use the logarithmic Sobolev inequality to estimate events with small probability. The new idea is to introduce a “convexified measure” so that the local statistics are preserved under this convexification.
Effect of dispersion correction on the Au(1 1 1)-H2O interface: A first-principles study
Authors: Nadler Roger , Sanz Javier Fdez.
Published: September 2012

A theoretical study of the H2O-Au(1 1 1) interface based on first principles density functional theory (DFT) calculations with and without inclusion of dispersion correction is reported. Three different computational approaches are considered. First, the standard generalized gradient approximation (GGA) functional PBE is employed. Second, an additional energy term is further included that adds a semi-empirically derived dispersion correction (PBE-D2), and, finally, a recently proposed functional that includes van der Waals (vdW) interactions directly in its functional form (optB86b-vdW) was used to represent the state-of-the art of DFT functionals. The monomeric water adsorption was first considered in order to explore the dependency of geometry on the details of the model slab used to represent it (size, thickness, coverage). When the dispersion corrections are included the Au-H2O interaction is stronger, as manifested by the smaller dAu-O and stronger adsorption energies. Additionally, the interfacial region between Au(1 1 1) slab surfaces and a liquid water layer was investigated with Born-Oppenheimer molecular dynamics (BOMD) using the same functionals. Two or three interfacial orientations can be determined, depending on the theoretical methodology applied. Closest to the surface, H2O is adsorbed O-down, whereas further away it is oriented with one OH bond pointing to the surface and the molecular plane parallel to the normal direction. For the optB86b-vdW functional a third orientation is found where one H atom points into the bulk water layer and the second OH bond is oriented parallel to the metal surface. As for the water density in the first adsorption layer we find a very small increase of roughly 8%. From the analysis of vibrational spectra a weakening of the H-bond network is observed upon the inclusion of the Au(1 1 1) slab, however, no disruption of H-bonds is observed. While the PBE and PBE-D2 spectra are very similar, the optB86b-vdW spectrum shows that the H-bonds are even more weakened.
Controlling the interface composition of core-shell and axial heterojunction nanowires
Authors: Vastola G. , Shenoy V. B. , Zhang Y.-W.
Published: September 2012

Composition profile across an interface in a core/shell or axial heterojunction nanowire often plays an important role in dictating its electronic, optical and magnetic properties. The control of composition profiles to achieve optimal performance still remains a challenge. In the present work, we formulate a theoretical model which accounts for three key factors that completely control the interface composition profile: the deposition flux of individual components, the atomic exchange rate between the surface and its sub-surface layer, and the thermodynamic driving force for surface segregation. We validate the model by matching its predictions with the experimental results for thin film growth. We then apply the model to the growth of core/shell and axial heterojunction nanowires and show that both abrupt and diffuse interface composition profiles can be achieved by tuning the growth parameters, providing a predictive approach for controlling interface composition distribution.
Amorphous Slater-Pauling like behaviour in magnetic nanoparticles alloys synthesized in liquids
Authors: Boyer Paul , Ménard David , Meunier Michel
Published: September 2012

Nanoparticles of Fe, Co, Ni, and their alloys, with an average diameter of 12 nm were synthesized in liquids using a laser. Their saturation magnetization exhibited a Slater-Pauling-like behaviour with two main differences compared to that expected in bulk materials. First, the amplitude of the magnetization was found to be roughly 5 times smaller. Second, the disappearance of the ferromagnetic (FM) behaviour occurred at Ni instead of the expected Ni0.6Cu0.4. The behaviour can be explained by the presence of non-magnetic oxidized shells which reduced the fraction of ferromagnetic atoms and induce through strain an amorphous structure in the metallic core. Annealing at 500 K leads to some crystallization of the particles and thus to a partial recovery of the expected magnetization.
Performance improvement of a measurement station for superconducting cable test
Authors: Arpaia Pasquale , Bottura Luca , Montenero Giuseppe , Naour Sandrine Le
Published: September 2012

A fully digital system, improving measurements flexibility, integrator drift, and current control of superconducting transformers for cable test, is proposed. The system is based on a high-performance integration of Rogowski coil signal and a flexible direct control of the current into the secondary windings. This allows state-of-the-art performance to be overcome by means of out-of-the-shelf components: on a full-scale of 32 kA, current measurement resolution of 1 A, stability below 0.25 A  min−1, and controller ripple less than ±50 ppm. The system effectiveness has been demonstrated experimentally on the superconducting transformer of the Facility for the Research of Superconducting Cables at the European Organization for Nuclear Research (CERN).
Raman spectra investigation of InAlGaN quaternary alloys grown by metalorganic chemical vapor deposition
Authors: Hu S. Y. , Lee Y. C. , Feng Z. C. , Weng Y. H.
Published: September 2012

Raman analysis of the A1 (LO) mode of AlGaN-like phonons of the InAlGaN/GaN heterostructures in the composition range 1.38% ≦ In ≦ 2.73% and 8.01% ≦ Al ≦ 13.97% is presented. The line shape of A1 (LO) mode of AlGaN-like phonons was observed to exhibit a significant asymmetry and Raman linewidth toward the lower energy side. The spatial correlation model is discussed and is shown to account the line shape. The spatial correlation model calculations also indicate the lack of a long-range order in the higher Al to In ratio of InAlGaN/GaN alloys. These results were confirmed by x-ray diffraction and the correlation length L decreases as the increasing of Al to In ratio corresponding to the absence of the long-range order in the alloy. The Raman linewidth of the AlGaN-like A1 (LO) mode was found to exhibit a maximum at the higher Al to In ratio indicative of a random disordered alloy system.
Analysis of the lateral resolution of electrostatic force gradient microscopy
Authors: Dunaevskiy Mikhail , Alekseev Prokhor , Girard Paul , Lashkul Alexander , Lahderanta Erkki , Titkov Alexander
Published: September 2012

Signal measured by electrostatic force gradient microscopy (EFGM) is the z-gradient of the electrostatic force acting between the probe of an atomic force microscope (AFM) and the surface under study. A model is presented for calculating the z-gradient of the electrostatic interaction of the AFM probe with local charges in a dielectric layer at the surface. In the EFGM mode, the interaction of charges with only the probe tip apex should be taken into account. In this approach, a simplified expression can be derived for calculating the z-gradient of the electrostatic force. The model makes it possible to estimate the lateral resolution limit for EFGM imaging of individual charges and to simulate experimental EFGM images as a function of the tip-surface distance and the tip radius. The adequacy of the model was confirmed by quantitative simulation of the experimental EFGM images of local charges injected from the AFM probe into a planar array of Si nanocrystals in a thin SiO2 layer on a Si substrate.
Piezoelectric resonator arrays for tunable acoustic waveguides and metamaterials
Authors: Casadei Filippo , Delpero Tommaso , Bergamini Andrea , Ermanni Paolo , Ruzzene Massimo
Published: September 2012

One of the outstanding challenges in phononic crystals and acoustic metamaterials development is the ability to tune their performance without requiring structural modifications. We report on the experimental demonstration of a tunable acoustic waveguide implemented within a two-dimensional phononic plate. The waveguide is equipped with a periodic array of piezoelectric transducers which are shunted through passive inductive circuits. The resonance characteristics of the shunts lead to strong attenuation and to negative group velocities at frequencies defined by the circuits' inductance. The proposed waveguide illustrates the concept of a controllable acoustic logic port or of an acoustic metamaterial with tunable dispersion characteristics.
Bulk strain solitary waves in bonded layered polymeric bars with delamination
Authors: Dreiden G. V. , Khusnutdinova K. R. , Samsonov A. M. , Semenova I. V.
Published: September 2012

We report the registration of delamination induced variations in the dynamics of bulk strain solitary waves in layered polymeric bars with the glassy and rubber-like adhesives, for the layers made of the same material. The key phenomenon in a layered structure with the glassy bonding is the delamination caused fission of a single incident soliton into a wave train of solitons, with the detectable increase in the amplitude of the leading solitary wave. The significant feature of bulk strain solitons in structures bonded with the rubber-like adhesive is the generation of radiating solitary waves, whilst co-propagating ripples disappear in the delaminated area. The observed variations may be used for the detection of delamination in lengthy layered structures.
Features of temperature dependence of contact resistivity in ohmic contacts on lapped n-Si
Authors: Sachenko A. V. , Belyaev A. E. , Boltovets N. S. , Vinogradov A. O. , Kladko V. P. , Konakova R. V. , Kudryk Ya. Ya. , Kuchuk A. V. , Sheremet V. N. , Vitusevich S. A.
Published: September 2012

The temperature dependence of contact resistivity ρc in lapped silicon specimens with donor concentrations of 5 × 1016, 3 × 1017, and 8 × 1017 cm−3 was studied experimentally. We found that, after decreasing part of the ρc(T) curve in the low temperature range, an increasing part is registered with increasing temperature T. It is demonstrated that the formation of contact to a lapped Si wafer results in the generation of high dislocation density in the near-surface region of the semiconductor and also in ohmic contact behavior. In this case, current flows through the metal shunts associated with dislocations. The theory developed is in good agreement with experimental results.
Growth of (111) oriented NiFe2O4 polycrystalline thin films on Pt (111) via sol-gel processing
Authors: Seifikar Safoura , Tabei Ali , Sachet Edward , Rawdanowicz Thomas , Bassiri-Gharb Nazanin , Schwartz Justin
Published: September 2012

Polycrystalline NiFe2O4 (NFO) thin films are grown on (111) platinized Si substrates via chemical solution processing. θ-2θ x-ray diffraction, x-ray pole figures and electron diffraction indicate that the NFO has a high degree of 〈111〉 uniaxial texture normal to the film plane. The texturing is initiated by nucleation of (111) planes at the Pt interface and is enhanced with decreasing film thickness. As the NFO magnetic easy-axis is 〈111〉, the out-of-plane magnetization exhibits improved Mr/Ms and coercivity with respect to randomly oriented films on silicon substrates. The out-of-plane Mr/Ms ratio for (111) textured NFO thin film is improved from 30% in 150 nm-thick films to above 70% in 50 nm-thick films. The improved out-of-plane magnetic anisotropy is comparable to epitaxial NFO films of comparable thickness deposited by pulsed laser deposition and sputtering.
Ab initio long-range interaction and adiabatic channel capture model for ultracold reactions between the KRb molecules
Authors: Buchachenko A. A. , Stolyarov A. V. , Szczȩśniak M. M. , Chałasiński G.
Published: September 2012

The coefficients at the lowest-order electrostatic, induction, and dispersion terms of the anisotropic long-range potential between the two KRb(1Σ+) molecules are evaluated through the static and dynamic molecular properties using the ab initio coupled cluster techniques. Adiabatic channel potentials for the ground-state molecules are obtained and used for the numerical quantum capture probability calculations in the spirit of the statistical adiabatic channel models. Capture rate coefficients for indistinguishable (polarized) and distinguishable (unpolarized) molecules at temperatures below 10 μK agree well with those computed with the simple isotropic dispersion R−6 potential, but underestimate the measured ones [Ospelkaus et al., Science 327, 853 (2010)10.1126/science.1184121] up to a factor of 3. Preliminary assessment of the effects of higher-order long-range terms, retardation of dispersion forces, and magnetic dipole–dipole interaction does not offer any clear perspectives for drastic improvement of the capture approximation for the reactions studied.
Direct laser-enabled graphene oxide–Reduced graphene oxide layered structures with micropatterning
Authors: Fatt Teoh Hao , Tao Ye , Soon Tok Eng , Wei Ho Ghim , Haur Sow Chorng
Published: September 2012

We present a versatile technique to create three dimensional graphene oxide (GO)-reduced GO (rGO) stacked-layered structure with the added attribute that micropatterns could be defined in each layer. We used focused laser beam to convert GO to rGO and create micropatterns of rGO on a heated substrate with GO spin-coated on it. The sample was then sonicated. Either the (1) micropatterned rGO (laser scanned region) or (2) micropatterned GO (unscanned region) could be preferentially removed depending on laser power and temperature of the substrate. A new layer of GO was then spin-coated and thus achieving 3D multilayered and patterned structure.
Nonlinear acoustic impedance of thermoacoustic stack
Authors: Ge Huan , Fan Li , Xiao Shu-yu , Tao Sha , Qiu Mei-chen , Zhang Shu-yi , Zhang Hui
Published: September 2012

In order to optimize the performances of the thermoacoustic refrigerator working with the high sound pressure level, the nonlinear acoustic characteristics of the thermoacoustic stack in the resonant pipe are studied. The acoustic fluid impedance of the stack made of copper mesh and set up in a resonant pipe is measured in the acoustic fields with different intensities. It is found that when the sound pressure level in the pipe increases to a critical value, the resistance of the stack increases nonlinearly with the sound pressure, while the reactance of the stack keeps constant. Based on the experimental results, a theory model is set up to describe the acoustic characteristics of the stack, according to the rigid frame theory and Forchheimmer equation. Furthermore, the influences of the sound pressure level, operating frequency, volume porosity, and length of the stack on the nonlinear impedance of the stack are evaluated.
Spatial angular positioning device with three-dimensional magnetoelectric sensors
Authors: Huong Giang D. T. , Duc P. A. , Ngoc N. T. , Hien N. T. , Duc N. H.
Published: September 2012

This paper reports on the development of a novel simple three-dimensional geomagnetic device for sensing the spatial azimuth and pitch positions by using three one-dimensional magnetoelectric sensors assembled along three orthogonal axes. This sensing device combines piezoelectric transducer plates and elongated high-performance Ni-based Metglas ribbons. It allows the simultaneous detection of all three orthogonal components of the terrestrial magnetic field. Output signals from the device components are provided in form of sine and/or cosine functions of both the rotation azimuth and the pitch angles, from which the total intensity as well as the inclination angle of the Earth's magnetic field is determined in an overall field resolution of better than 10−4 Oe and an angle precision of ±0.1°, respectively. This simple and low-cost geomagnetic-field device is promising for the automatic determination and control of the mobile transceiver antenna's orientation with respect to the position of the related geostationary satellite.
Crossover time in relative fluctuations characterizes the longest relaxation time of entangled polymers
Authors: Uneyama Takashi , Akimoto Takuma , Miyaguchi Tomoshige
Published: September 2012

In entangled polymer systems, there are several characteristic time scales, such as the entanglement time and the disengagement time. In molecular simulations, the longest relaxation time (the disengagement time) can be determined by the mean square displacement (MSD) of a segment or by the shear relaxation modulus. Here, we propose the relative fluctuation analysis method, which is originally developed for characterizing large fluctuations, to determine the longest relaxation time from the center of mass trajectories of polymer chains (the time-averaged MSDs). Applying the method to simulation data of entangled polymers (by the slip-spring model and the simple reptation model), we provide a clear evidence that the longest relaxation time is estimated as the crossover time in the relative fluctuations.
Suppressing on-chip electromagnetic crosstalk for spin qubit devices
Authors: Blanvillain S. , Colless J. I. , Reilly D. J. , Lu H. , Gossard A. C.
Published: September 2012

We report the development and performance of on-chip interconnects designed to suppress electromagnetic crosstalk in spin qubit device architectures with the large number of gate electrodes needed for multi-qubit operation. Our design improves the performance of typical device interconnects via the use of miniaturised ohmic contacts and interspersed ground guards. Low-temperature measurements and numerical simulation confirm that control and readout signal crosstalk can be suppressed to levels of order 1%, from dc to 1 GHz.
Utilizing upper hybrid resonance for high density plasma production and negative ion generation in a downstream region
Authors: Sahu Debaprasad , Bhattacharjee Sudeep
Published: September 2012

Localized wave-induced resonances are created by microwaves launched directly into a multicusp (MC) plasma device in the k ⊥ B mode, where k is the wave vector and B is the static magnetic field. The resonance zone is identified as upper hybrid resonance (UHR), and lies r = ∼22 mm away from the MC boundary. Measurement of radial wave electric field intensity confirms the right hand cutoff of the wave (r = 22.5–32.1 mm) located near the UHR zone. A sharp rise in the corresponding electron temperature in the resonance region by ∼13 eV from its value away from resonance at r = 0, is favorable for the generation of vibrationally excited molecules of hydrogen. A transverse magnetic filter allows cold electrons (∼1–2 eV) to pass into the downstream region where they generate negative ions by dissociative attachment. Measurements of electron energy distribution function (EEDF) support the viewpoint. H− current density of ∼0.26 mA/cm2 is obtained at a wave power density of ∼3 W/cm2 at 2.0 mTorr pressure, which agrees reasonably well with results obtained from a steady state model using particle balance equations.
Mechanisms of infrared photoluminescence in HgTe/HgCdTe superlattice
Authors: Shao Jun , Lu Wei , Tsen G. K. O. , Guo Shaoling , Dell J. M.
Published: September 2012

Temperature (11–250 K) and excitation power (5–480 mW) dependent infrared photoluminescence (PL) measurements are conducted on a HgTe/Hg0.05Cd0.95Te superlattice (SL) sample in a spectral range of 5–18 μm with adequate spectral resolution and signal-to-noise ratio. Three PL components are identified from the evolution of the PL lineshape with temperature although the full-width at half-maximum (FWHM) of the whole PL signal is only about 7 meV at 11 K, for which different changes of the energy, FWHM, and integral intensity are evidenced. The mechanisms are clarified that the medium-energy component is due to electron-heavy hole intersubband transition, while the low-energy (LE) component correlates to localized states and the high-energy (HE) one may originate in interfacial inhomogeneous chemical intermixing and Brillouin-zone boundary effects. The LE and HE component-related effects are responsible for the PL quality of the SL at the temperatures well below and above 77 K, respectively.
Applications of pulsed laser ablation for enhanced gold nanofluids
Authors: Hur Tae-Bong , Phuoc Tran X. , Chyu Minking K. , Romanov Vyacheslav N.
Published: September 2012

We report the exploration for enhanced gold nanofluids by using the laser ablation technique of which pulsed laser ablates energetic clusters from the bulk target immersed into liquid environment. By employing pulsed laser ablation, the behavior of optical absorption band was investigated on spherical Au nanoparticles that approach to the extremely small size of 1 nm, and rod-shaped Au nanoparticles were synthesized by controlling the aggregation behavior of energetic clusters in fluids. It was found that a nominal change in particle size induces a significant change in absorption band energy in the size range. In addition, the attempt to control the growth kinetics of particles has made remarkable progress on the synthesis of environmentally friendly gold nanorods. Experimental evidences show that the laser ablation synthesis can be widely used as a potential method for advanced gold nanofluids.
Early stages of mechanical deformation in indium phosphide with the zinc blende structure
Authors: Almeida C. M. , Prioli R. , Wei Q. Y. , Ponce F. A.
Published: September 2012

Nanoindentations were performed on a cubic semiconductor using a cono-spherical diamond tip with a 260 nm radius. The tip produces a single point of contact with the crystal surface allowing indentations with nano-scale dimensions. The early stages of deformation on (100) InP with the zinc-blende structure were observed to happen by the sequential introduction of metastable dislocation loops along the various slip planes directly beneath the point of contact. Locking of the dislocations loops forms a hardened region that acts as an extended tip during subsequent indentation, eventually leading to multiple bulk-like displacements (pop-in events) and to material pile up in the vicinity of the indentation pit. The first pop-in marks the transition of deformation from the nanometer to the micrometer scale.
CCSD(T) potential energy and induced dipole surfaces for N2–H2(D2): Retrieval of the collision-induced absorption integrated intensities in the regions of the fundamental and first overtone vibrational transitions
Authors: Buryak Ilya , Lokshtanov Sergei , Vigasin Andrey
Published: September 2012

The present work aims at ab initio characterization of the integrated intensity temperature variation of collision-induced absorption (CIA) in N2–H2(D2). Global fits of potential energy surface (PES) and induced dipole moment surface (IDS) were made on the basis of CCSD(T) (coupled cluster with single and double and perturbative triple excitations) calculations with aug-cc-pV(T,Q)Z basis sets. Basis set superposition error correction and extrapolation to complete basis set (CBS) limit techniques were applied to both energy and dipole moment. Classical second cross virial coefficient calculations accounting for the first quantum correction were employed to prove the quality of the obtained PES. The CIA temperature dependence was found in satisfactory agreement with available experimental data.
The virial theorem for the smoothly and sharply, penetrably and impenetrably confined hydrogen atom
Authors: Katriel Jacob , Montgomery H. E.
Published: September 2012

Confinement of atoms by finite or infinite boxes containing sharp (discontinuous) jumps has been studied since the fourth decade of the previous century, modelling the effect of external pressure. Smooth (continuous) counterparts of such confining potentials, that depend on a parameter such that in an appropriate limit they coincide with the sharp confining potentials, are investigated, with an emphasis on deriving the corresponding virial and Hellmann-Feynman theorems.
On the mechanism of electrochemical modulation of plasmonic resonances
Authors: Shao L.-H. , Ruther M. , Linden S. , Wegener M. , Weissmüller J.
Published: September 2012

Recent electrochemical experiments on gold-based photonic metamaterials have shown a sizable reversible tuning and modulation of plasmonic resonances. Here, we study the mechanism of the electrochemical modulation by measuring the change of the resonance transmittance and resonance frequency during underpotential deposition of Pb, Cu, and electrosorption of OH. The electric resistance change of the resonators is identified as decisive for the resonance transmittance change, while the space-charge layer at the metal surface shifts the resonance frequency.
Athermal and tunable operations of 850 nm vertical cavity surface emitting lasers with thermally actuated T-shape membrane structure
Authors: Sano Hayato , Nakata Norihiko , Nakahama Masanori , Matsutani Akihiro , Koyama Fumio
Published: September 2012

We demonstrate the athermal operation and the wavelength tuning of 850 nm GaAs-based vertical cavity surface emitting lasers with a thermally actuated cantilever structure. The thermal actuation of a top distributed Bragg reflector mirror enables us to compensate the temperature drift of lasing wavelengths. The temperature dependence of lasing wavelengths could be controlled from −0.011 nm/K to −0.18 nm/K by changing the cantilever length. In addition, a T-shape membrane structure was introduced for efficient electro-thermal tuning. A small temperature dependence of −0.011 nm/K and wavelength tuning of 4 nm were obtained.
Cluster synchronization of spiking induced by noise and interaction delays in homogenous neuronal ensembles
Authors: Franović Igor , Todorović Kristina , Vasović Nebojša , Burić Nikola
Published: September 2012

Properties of spontaneously formed clusters of synchronous dynamics in a structureless network of noisy excitable neurons connected via delayed diffusive couplings are studied in detail. Several tools have been applied to characterize the synchronization clusters and to study their dependence on the neuronal and the synaptic parameters. Qualitative explanation of the cluster formation is discussed. The interplay between the noise, the interaction time-delay and the excitable character of the neuronal dynamics is shown to be necessary and sufficient for the occurrence of the synchronization clusters. We have found the two-cluster partitions where neurons are firmly bound to their subsets, as well as the three-cluster ones, which are dynamical by nature. The former turn out to be stable under small disparity of the intrinsic neuronal parameters and the heterogeneity in the synaptic connectivity patterns.
The electron geodesic acoustic mode
Authors: Chakrabarti N. , Guzdar P. N. , Kaw P. K.
Published: September 2012

In this report, a novel new mode, named the electron geodesic acoustic mode, is presented. This mode can occur in toroidal plasmas like the conventional geodesic acoustic mode (GAM). The frequency of this new mode is much larger than that of the conventional GAM by a factor equal to the square root of the ion to electron mass ratio.
Note: Automatic laser-to-optical-fiber coupling system based on monitoring of Raman scattering signal
Authors: Park Kyoung-Duck , Kim Yong Hwan , Park Jin-Ho , Yim Sang-Youp , Jeong Mun Seok
Published: September 2012

We developed an automatic laser-to-optical-fiber coupling (ALOC) system that is based on the difference in the Raman scattering signals of the core and cladding of the optical fiber. This system can be easily applied to all fields of fiber optics since it can perform automatic optical coupling within a few seconds regardless of the core size or the condition of the output end of the optical fiber. The coupling time for a commercial single-mode fiber for a wavelength of 632.8 nm (core diameter: 9 μm, cladding diameter: 125 μm) is ∼1.5 s. The ALOC system was successfully applied to single-mode-fiber Raman endoscopy for the measurement of the Raman spectrum of carbon nanotubes.
Phase-partitioning and site-substitution patterns of molybdenum in a model Ni-Al-Mo superalloy: An atom-probe tomographic and first-principles study
Authors: Tu Yiyou , Mao Zugang , Seidman David N.
Published: September 2012

Atom-probe tomography (APT) and first-principles calculations are employed to investigate the partitioning of Mo in the γ(f.c.c.)-and γ′(L12)-phases in a model Ni-6.5Al-9.9Mo at. % superalloy. Mo is experimentally observed to partition preferentially to the γ(f.c.c.)-matrix, which is consistent with the smaller value of the γ(f.c.c.)-matrix substitutional formation-energy, with a driving force of 0.707 eV for partitioning as determined by first-principles calculations. APT measurements of the γ′(L12)-precipitate-phase composition and Al-, Mo-centered partial radial distribution functions indicate that Mo occupies the Al sublattice sites of the Ni3Al(L12) phase. The preferential site-substitution of Mo at Al sublattice sites is confirmed by first-principles calculations.
Frequency comb assisted mid-infrared spectroscopy of cold molecular ions
Authors: Asvany Oskar , Krieg Jürgen , Schlemmer Stephan
Published: September 2012

A mid-infrared spectrometer consisting of a high power optical parametric oscillator, a frequency comb, and a cold ion trap is described and characterized. The idler frequency at 3 μm is measured accurately by analyzing the pump and signal beat frequencies with the comb. This is done via two spectrum analyzers, allowing for a wide and continuous scanning ideal for spectroscopy of cold molecules with unknown spectra. The potential of this approach is demonstrated by measuring a ro-vibrational line of \documentclass[12pt]{minimal}\begin{document}${\rm CH}_5^+$\end{document} CH 5+ in a 22-pole ion trap via action spectroscopy of only several thousand cold ions. The current setup limits the precision of the line center frequency determination to some 100 kHz with ample room for future improvements. Following this approach, ground state combination differences of molecular ions can be predicted in order to identify them in astronomical objects.