bluuebunny/crossref_metadata_2025 huggingface dataset:
Rhenium and technetium bi- and tricarbonyl complexes in a new strategy for biomolecule incorporation using click chemistry
Authors: Hayes Thomas R. , Kasten Benjamin B. , Barnes Charles L. , Benny Paul D.
Published: March 2014

Bi and tri-carbonyl Re/99mTc complexes can be selectively formed by temperature control at macroscopic and radio-chemical concentrations using a combination of Huisgen “clicked” and phosphine ligands.
Polyethylene glycol (PEG) as a reusable solvent medium for an asymmetric organocatalytic Michael addition. Application to the synthesis of bioactive compounds
Authors: Feu Karla S. , de la Torre Alexander F. , Silva Sandrina , de Moraes Junior Marco A. F. , Corrêa Arlene G. , Paixão Márcio W.
Published: March 2014

A highly stereoselective organocatalytic Michael addition of aldehydes to trans-β-nitrostyrenes using PEG as a recyclable solvent medium is presented.
Highly active, water-compatible and easily separable magnetic mesoporous Lewis acid catalyst for the Mukaiyama–Aldol reaction in water
Authors: Zhang Fang , Wu Xiaotao , Liang Chao , Li Xiaoyan , Wang Zhen , Li Hexing
Published: March 2014

A multifunctional magnetic mesoporous silica supported Yb(OTf)3 composite was demonstrated to be an efficient and easily recyclable catalyst for the Mukaiyama–Aldol reaction in water.
The biology and synthesis of α-hydroxytropolones
Authors: Meck Christine , D'Erasmo Michael P. , Hirsch Danielle R. , Murelli Ryan P.
Published: March 2014

α-Hydroxytropolones are promising leads for a diverse range of therapeutic applications. The following review will discuss the biological studies on α-hydroxytropolones and the synthetic methods available to access them.
Novel catalyst by immobilizing a phosphotungstic acid on polymer brushes and its application in oxidative desulfurization
Authors: Zhu Mingyuan , Luo Guangqin , Kang Lihua , Dai Bin
Published: March 2014

In the study, an HPW–PDMAEMA–SiO2 (phosphotungstic acid (HPW); poly-N,N-dimethylaminoethyl methacrylate (PDMAEAM)) catalyst was successfully synthesized.
Synthetic exploitation of halogenated alkenes containing EWG: benzotriazole-mediated synthesis of benzoazetines and thermal transformations
Authors: Tuyun Amac Fatih
Published: March 2014

The stable benzoazetines (5a–d) based on nitrovinyl moieties have been synthesizedviatransamination of bisbenzotriazolyl derivatives (2a–c).
A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase: tunable direct bioelectrocatalysis
Authors: Sarauli David , Xu Chenggang , Dietzel Birgit , Schulz Burkhard , Lisdat Fred
Published: March 2014

Differently sulfonated polyaniline copolymers have been utilized as matrices for the entrapment of PQQ-GDH, resulting in a direct bioelectrocatalytic response together with a colour change upon addition of the substrate.
Development of an X-ray pixel detector with multi-port charge-coupled device for X-ray free-electron laser experiments
Authors: Kameshima Takashi , Ono Shun , Kudo Togo , Ozaki Kyosuke , Kirihara Yoichi , Kobayashi Kazuo , Inubushi Yuichi , Yabashi Makina , Horigome Toshio , Holland Andrew , Holland Karen , Burt David , Murao Hajime , Hatsui Takaki
Published: March 2014

This paper presents development of an X-ray pixel detector with a multi-port charge-coupled device (MPCCD) for X-ray Free-Electron laser experiments. The fabrication process of the CCD was selected based on the X-ray radiation hardness against the estimated annual dose of 1.6 × 1014 photon/mm2. The sensor device was optimized by maximizing the full well capacity as high as 5 Me- within 50 μm square pixels while keeping the single photon detection capability for X-ray photons higher than 6 keV and a readout speed of 60 frames/s. The system development also included a detector system for the MPCCD sensor. This paper summarizes the performance, calibration methods, and operation status.
Global solutions of restricted open-shell Hartree-Fock theory from semidefinite programming with applications to strongly correlated quantum systems
Authors: Veeraraghavan Srikant , Mazziotti David A.
Published: March 2014

We present a density matrix approach for computing global solutions of restricted open-shell Hartree-Fock theory, based on semidefinite programming (SDP), that gives upper and lower bounds on the Hartree-Fock energy of quantum systems. While wave function approaches to Hartree-Fock theory yield an upper bound to the Hartree-Fock energy, we derive a semidefinite relaxation of Hartree-Fock theory that yields a rigorous lower bound on the Hartree-Fock energy. We also develop an upper-bound algorithm in which Hartree-Fock theory is cast as a SDP with a nonconvex constraint on the rank of the matrix variable. Equality of the upper- and lower-bound energies guarantees that the computed solution is the globally optimal solution of Hartree-Fock theory. The work extends a previously presented method for closed-shell systems [S. Veeraraghavan and D. A. Mazziotti, Phys. Rev. A 89, 010502–R (2014)]. For strongly correlated systems the SDP approach provides an alternative to the locally optimized Hartree-Fock energies and densities with a certificate of global optimality. Applications are made to the potential energy curves of \documentclass[12pt]{minimal}\begin{document}${\rm C}_{\textrm {2}}$\end{document}C2, CN, \documentclass[12pt]{minimal}\begin{document}${\rm Cr}_{\textrm {2}}$\end{document} Cr 2, and \documentclass[12pt]{minimal}\begin{document}${\rm NO}_{\textrm {2}}$\end{document} NO 2.
The influence of morphology on the low- and high-strain-rate compaction response of CeO2 powders
Authors: Fredenburg D. A. , Koller D. D. , Coe Joshua D. , Kiyanda C. B.
Published: March 2014

The low- and high-strain-rate compaction response of three distinct morphology CeO2 powders was measured experimentally. At low-strain-rates, the compression path was found to vary with initial particle morphology as a result of differences in initial packing structure and particle rearrangement at low stresses. However, similar compression responses were observed at higher stresses under low-strain-rate loading. Dynamic experiments were performed at impact velocities between 0.15 and 0.78 km/s, and resulted in compaction stresses of 0.51-4.59 GPa in the powders. In contrast to the behavior observed at low stresses and low-strain-rates, dynamic loading resulted in a similar compaction response for all morphology powders. The dynamic results were treated with a Hayes equation of state augmented with a P-α compaction model, and good agreement between experimental and theoretical results was achieved. From the observed similarities in compressibility for the three morphology powders at elevated stresses at both low- and high-strain-rates, a relationship is proposed linking the measured strength properties at low-strain-rates to those controlling the compaction response under dynamic loading.
Multi-peak solution for nonlinear magnetic Choquard type equation
Authors: Sun Xiaomei , Zhang Yimin
Published: March 2014

In this paper, we study a class of nonlinear magnetic Choquard type equation involving a magnetic potential and nonlocal nonlinearities. By using the method of penalization argument, we show that there exists a family of solutions having multiple concentration regions which are concentrate at the minimum points of potential V.
Band engineering of GaN/AlN quantum wells by Si dopants
Authors: Zhuo Xiaolong , Ni Jianchao , Li Jinchai , Lin Wei , Cai Duanjun , Li Shuping , Kang Junyong
Published: March 2014

The electronic properties of GaN/AlN quantum wells are engineered by Si doped in different positions with the aid of the first-principle calculations. The local potential where the dopant located is dragged down as a result of negative center induced by the Si atom, leading to a different shift of the potential, and further affects the band bending and carrier distribution. The band profiles are depicted by analyzing the projected densities of states, it is found that the different positions of Si doping lead to a different band bending owing to the modified polarization fields. The spatial distributions of electrons and holes plotted by the partial charge densities reveal that electrons and holes experience redistribution by Si dopant in different positions. The above results demonstrate that the effect of polarization on the band bending has been significantly modulated by Si doped in different positions. Such modification of electronic structure is especially valuable for the fabrication of GaN/AlN QWs under desired control.
Development of a machine for automatically measuring static/dynamic running parallelism in linear guideways
Authors: Hsieh Tung-Hsien , Huang Hsueh-Liang , Jywe Wen-Yuh , Liu Chien-Hung
Published: March 2014

This work develops a machine for automatically measuring static/dynamic running parallelism for use in the linear guideway manufacturing industry. The automatic static/dynamic running parallelism measurement machine consists of a running parallelism measurement system, a linear motor, a precision granite air-suspension table, and a PC-based human-machine interface. The machine can be used simultaneously to measure the horizontal and vertical running parallelism of a linear guideway and automatically determine its accuracy. The measured parallelism is digitalized and analyzed to detect turning points in the linear guideway. The results concerning the accuracy of the running parallelism are not affected by the measurement platform. Experimental results showed that the standard deviation of the running parallelism measurement system is 0.4 μm and the measuring time is about 10 s for every 1000 mm of length (equal to a measuring speed of 0.1 m/s); this measurement time is 80% shorter than that of a traditional measurement system (which has a maximum speed of 1 m/s, a maximum sampling frequency of 100 kHz, and a maximum measurement length of 2000 mm).
Development and intrinsic properties of hexagonal ferromagnetic (Zr,Ti)Fe2
Authors: Zhang W. Y. , Li X. Z. , Valloppilly S. , Skomski R. , Shield J. E. , Sellmyer D. J.
Published: March 2014

Nanocrystalline Ti0.75Zr0.25Fe2+x (x = 0-0.4) and Ti0.75−yByZr0.25Fe2.4 (y = 0-0.35) with high saturation magnetization have been fabricated by the melt-spinning technique. Nanocrystalline Ti0.75Zr0.25Fe2+x consists of the hexagonal C14 Laves phase (Ti,Zr)Fe2. Fe addition decreases the lattice parameter a and shrinks the cell volume. The antiferromagnetic Fe-Fe interactions may decrease with the increase of x, leading to a significant enhancement of saturation polarization (Js) and Curie temperature (Tc). The magnetocrystalline anisotropy constant K also increases with increasing x. Excessive Fe addition (x > 0.25) may induce structural disorder which lowers the Js and Tc. Nanocrystalline Ti0.75−yByZr0.25Fe2.4 is composed of hexagonal (Ti,Zr)Fe2 and Fe-rich amorphous phases with relatively high Js. The lattice parameters a, c and cell volume V are almost unchanged with the increase of y for y ≥ 0.16. Simultaneously, the Tc of (Ti,Zr)Fe2 remains unchanged, indicating that B does not enter this lattice but takes part in forming the amorphous phase, in good agreement with the X-ray diffraction results. The volume fraction of the amorphous phase increases with the increase of B content and results in a large enhancement of Js up to 10.8 kG. Further B addition (y > 0.30) decreases Js, possibly due to the decrease of the Js of the amorphous phase.
The Picard–Fuchs equations for complete hyperelliptic integrals of even order curves, and the actions of the generalized Neumann system
Authors: Fedorov Yuri , Pantazi Chara
Published: March 2014

We consider a family of genus 2 hyperelliptic curves of even order and obtain explicitly the systems of 5 linear ordinary differential equations for periods of the corresponding Abelian integrals of first, second, and third kind, as functions of some parameters of the curves. The systems can be regarded as extensions of the well-studied Picard–Fuchs equations for periods of complete integrals of first and second kind on odd hyperelliptic curves. The periods we consider are linear combinations of the action variables of several integrable systems, in particular the generalized Neumann system with polynomial separable potentials. Thus the solutions of the extended Picard–Fuchs equations can be used to study various properties of the actions.
Power-law spectra formed by stretching polymers in decaying isotropic turbulence
Authors: Watanabe Takeshi , Gotoh Toshiyuki
Published: March 2014

The spectral dynamics of isotropic decaying turbulence with polymer additives is numerically investigated using a hybrid Eulerian-Lagrangian approach with making use of large-scale parallel computation. We found that the kinetic energy and pressure variance spectra obeyed the power law E(k) ∼ k−α and Ep(k) ∼ k−β in the scale range below the Kolmogorov length lK when the turbulence sufficiently decayed while the Weissenberg number Wi remained greater than unity. The exponents α and β were found to be α = 4.1 − 4.6 and β = 2.8 − 3.2, respectively, and were found to decrease with increasing Wi. We discuss the similarities and differences between the present results and the results of previous experimental and numerical studies for elastic turbulence, which is characterized by Wi ≫ 1 and a Reynolds number below unity.
GaAs/AlGaAs quantum wells with indirect-gap AlGaAs barriers for solar cell applications
Authors: Noda T. , Otto L. M. , Elborg M. , Jo M. , Mano T. , Kawazu T. , Han L. , Sakaki H.
Published: March 2014

We have fabricated GaAs/AlGaAs quantum well (QW) solar cells in which 3 nm-thick QWs and indirect-gap Al0.78Ga0.22As barriers are embedded, and we studied extraction processes of photogenerated carriers in this QW system. The photocurrent under 700 nm light illumination at voltages close to the open-circuit voltage shows only a small reduction, indicating that the carrier recombination inside QWs is largely suppressed. We attribute this result to an efficient extraction of electrons from the QWs through the X-valley of AlGaAs. The insertion of QWs is shown to be effective in extending the absorption wavelengths and in enhancing the photocurrent. The use of indirect-gap materials as barriers is found to enhance carrier extraction processes, and result in an improved performance of QW solar cells.
Design of a low-emittance lattice for 3.5 GeV synchrotron light source
Authors: Kim Eun-San
Published: March 2014

We investigate a lattice design for a low-emittance, high-brilliance intermediate energy synchrotron light source that is being intensively performed in the world. We present the design results in detail for a non-achromatic double bend achromat lattice with an emittance of 1.1 nm and 597.6 m circumference. Each superperiod has 4 straight sections, 7 m, 5.4 m, and 2 × 2.8 m in length, giving a total of 60 straight sections in the ring. The lattice is designed to be flexible and also provides an achromatic optics with an emittance of 3.2 nm. The lattice provides high brilliance at a photon energy of a few tens of keV, which meets the requirements of hard X-ray synchrotron radiation users. We investigated the dynamic aperture in the lattice with machine errors using a simulation method that achieves the optimal tune for the ring. The low-emittance lattice provides sufficient dynamic aperture after closed orbit distortion correction. We show an estimate of variations of emittance, energy spread, and dynamic aperture due to a wiggler in the straight sections. We present the design of an injection scheme for full energy injection, the space allocation in injection section, and the particle dynamics of injected beam. Particle tracking after beam injection was performed to examine the validity of the injection scheme. Our design lattice shows good optimization in terms of the emittance, number of straight sections, brilliance, and circumference as a light source for 3.5 GeV beam energy.
Antiferromagnetic ordering in NdAuGe compound
Authors: Bashir A. K. H. , Tchoula Tchokonté M. B. , Snyman J. L. , Sondezi B. M. , Strydom A. M.
Published: March 2014

The compound NdAuGe was investigated by means of electrical resistivity, ρ(T), magnetic susceptibility, χ(T), magnetization, σ(μ0H), and specific heat, Cp(T), measurements. Powder X-ray diffraction studies confirm a hexagonal LiGaGe-type structure with space group P63mc (No. 186). ρ(T) data show normal metallic behaviour and a tendency toward saturation at higher temperatures. The low temperature ρ(T) data indicate a phase transition around 3.8 K. The low field dc χ(T) data show an antiferromagnetic anomaly associated with a Néel temperature at TN = 3.7 K close to the phase transition observed in ρ(T) results. At higher temperatures, χ(T) follows the paramagnetic Curie-Weiss behaviour with an effective magnetic moment μeff=3.546(4) μB and a paramagnetic Weiss temperature of θp=−6.1(4) K. The value obtained for μeff is close to the value of 3.62 μB expected for the free Nd3+-ion. σ(μ0H) shows a linear behaviour with applied field up to 3 T with an evidence of metamagnetic behaviour above 3 T. Cp(T) confirms the magnetic phase transition at TN = 3.4 K. The 4f-electron specific heat indicates a Schottky-type anomaly around 16.5 K with energy splitting Δ1=25.8(4) K and Δ2=50.7(4) K of the Nd3+ (J = 9/2) multiplet, that are associated with, respectively, the first and second excited states of the Nd3+-ion.
Kinetic Alfvén solitary and rogue waves in superthermal plasmas
Authors: Bains A. S. , Li Bo , Xia Li-Dong
Published: March 2014

We investigate the small but finite amplitude solitary Kinetic Alfvén waves (KAWs) in low β plasmas with superthermal electrons modeled by a kappa-type distribution. A nonlinear Korteweg-de Vries (KdV) equation describing the evolution of KAWs is derived by using the standard reductive perturbation method. Examining the dependence of the nonlinear and dispersion coefficients of the KdV equation on the superthermal parameter κ, plasma β, and obliqueness of propagation, we show that these parameters may change substantially the shape and size of solitary KAW pulses. Only sub-Alfvénic, compressive solitons are supported. We then extend the study to examine kinetic Alfvén rogue waves by deriving a nonlinear Schrödinger equation from the KdV equation. Rational solutions that form rogue wave envelopes are obtained. We examine how the behavior of rogue waves depends on the plasma parameters in question, finding that the rogue envelopes are lowered with increasing electron superthermality whereas the opposite is true when the plasma β increases. The findings of this study may find applications to low β plasmas in astrophysical environments where particles are superthermally distributed.
Effects of bias and temperature on the intersubband absorption in very long wavelength GaAs/AlGaAs quantum well infrared photodetectors
Authors: Liu X. H. , Zhou X. H. , Li N. , Wang L. , Sun Q. L. , Liao K. S. , Huang L. , Li Q. , Li Z. F. , Chen P. P. , Lu W.
Published: March 2014

The temperature- and bias-dependent photocurrent spectra of very long wavelength GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) are studied using spectroscopic measurements and corresponding theoretical calculations. It is found that the peak response wavelength will shift as the bias and temperature change. Aided by band structure calculations, we propose a model of the double excited states and explain the experimental observations very well. In addition, the working mechanisms of the quasi-bound state confined in the quantum well, including the processes of tunneling and thermionic emission, are also investigated in detail. We confirm that the first excited state, which belongs to the quasi-bound state, can be converted into a quasi-continuum state induced by bias and temperature. These obtained results provide a full understanding of the bound-to-quasi-bound state and the bound-to-quasi-continuum state transition, and thus allow for a better optimization of QWIPs performance.
Neutron irradiation effects on metal-gallium nitride contacts
Authors: Katz Evan J. , Lin Chung-Han , Qiu Jie , Zhang Zhichun , Mishra Umesh K. , Cao Lei , Brillson Leonard J.
Published: March 2014

We have measured the effect of fast and thermal neutrons on GaN Schottky barriers and ohmic contacts using current–voltage and transmission line method electrical techniques, optical, atomic force and scanning electron microscopy morphological techniques, and X-ray photoemission spectroscopy chemical techniques. These studies reveal a 1015 n/cm2 neutron threshold for Schottky barrier ideality factor increases, a 1015 n/cm2 fast plus thermal neutron threshold for ohmic contact sheet and contact resistance increases, and 1016 n/cm2 neutron fluence threshold for major device degradation identified with thermally driven diffusion of Ga and N into the metal contacts and surface phase changes. These results demonstrate the need for protecting metal-GaN contacts in device applications subject to neutron radiation.
Broadband sensitization of downconversion phosphor YPO4 by optimizing TiO2 substitution in host lattice co-doped with Pr3+-Yb3+ ion-couple
Authors: Li Kai-Yu , Liu Li-Ying , Wang Ru-Zhi , Xiao Si-Guo , Zhou Hua , Yan Hui
Published: March 2014

This study demonstrates a feasible and efficient route to alleviate the absorption problem of the terrestrial solar spectrum and enhance broadband luminescence from a promising down conversion powder phosphor YPO4 co-doped with Pr3+-Yb3+ lanthanide ion-couple: incorporating a third sensitizing transition metal ion, e.g., Ti4+. The x-ray powder diffraction results confirm the lattice substitution by the solid-state reaction doping rather than the formation of any secondary phase. The emission spectral results and the luminescence decay curve analysis show that the downconversion luminescence can be enhanced by 200%–300% and the quantum efficiency enhanced by more than 20% at the wavelength of around 980 nm, the best response spectrum for Si-based solar cells, by optimizing TiO2 doping concentration at 7 mol. %.
Enhanced ferromagnetism, metal-insulator transition, and large magnetoresistance in La1−xCaxMn1−xRuxO3 free of eg-orbital double-exchange
Authors: Liu M. F. , Du Z. Z. , Liu H. M. , Li X. , Yan Z. B. , Dong S. , Liu J.-M.
Published: March 2014

The structure, ionic valences, magnetism, and magneto-transport behaviors of mixed valence oxides La1−xCaxMn1−xRuxO3 are systematically investigated. The simultaneous substitutions of La3+ and Mn3+ ions by Ca2+ and Ru4+, respectively, are confirmed by the structural and ionic valence characterizations, excluding the presence of Mn4+ and Ru3+ ions. The enhanced ferromagnetism, induced metal-insulator transition, and remarkable magnetoresistance effect are demonstrated when the substitution level x is lower than ∼0.6, in spite of the absence of the Mn3+-Ru4+ eg-orbital double-exchange. These anomalous magnetotransport effects are discussed based on the competing multifold interactions associated with the Mn3+-Ru4+ super-exchange and strong Ru4+-Ru4+ hopping, while the origins for the metal-insulator transition and magnetoresistance effect remain to be clarified.
Lattice thermal conductivity of UO2 using ab-initio and classical molecular dynamics
Authors: Kim Hyoungchul , Kim Moo Hwan , Kaviany Massoud
Published: March 2014

We applied the non-equilibrium ab-initio molecular dynamics and predict the lattice thermal conductivity of the pristine uranium dioxide for up to 2000 K. We also use the equilibrium classical molecular dynamics and heat-current autocorrelation decay theory to decompose the lattice thermal conductivity into acoustic and optical components. The predicted optical phonon transport is temperature independent and small, while the acoustic component follows the Slack relation and is in good agreement with the limited single-crystal experimental results. Considering the phonon grain-boundary and pore scatterings, the effective lattice thermal conductivity is reduced, and we show it is in general agreement with the sintered-powder experimental results. The charge and photon thermal conductivities are also addressed, and we find small roles for electron, surface polaron, and photon in the defect-free structures and for temperatures below 1500 K.
Evolution of optical properties of tin film from solid to liquid studied by spectroscopic ellipsometry and ab initio calculation
Authors: Zhang D. X. , Shen B. , Zheng Y. X. , Wang S. Y. , Zhang J. B. , Yang S. D. , Zhang R. J. , Chen L. Y. , Wang C. Z. , Ho K. M.
Published: March 2014

The temperature dependent optical properties of tin film from solid to liquid were studied by spectroscopic ellipsometry and ab initio molecular dynamics simulations. The dielectric function of liquid Sn was different from solid, and an interband transition near 1.5 eV was easily observed in solid while it apparently disappeared upon melting. From the evolution of optical properties with temperature, an optical measurement to acquire the melting point by ellipsometry was presented. From first principles calculation, we show that the local structure difference in solid and liquid is responsible for this difference in the optical properties observed in experiment.
Three-dimensional magnetohydrodynamic Kelvin–Helmholtz instability of cylindrical flow with permeable boundaries
Authors: Kumar Awasthi Mukesh
Published: March 2014

We study the linear magnetohydrodynamic Kelvin–Helmholtz instability of the interface between two viscous, incompressible, and electrically conducting fluids. The phases are enclosed between two coaxial cylindrical porous layers with the interface through which mass and heat transfer takes place. The fluids are subjected to a constant magnetic field parallel to the streaming direction, and the suction/injection velocities for the fluids at the permeable boundaries are also taken into account. Here, we use an irrotational theory in which the motion and pressure are irrotational, and the viscosity enters through the jump in the viscous normal stress in the normal stress balance at the interface. We consider both asymmetric and axisymmetric disturbances in our analysis. A quadratic dispersion relation is deduced and stability criterion is given in terms of a critical value of relative velocity, as well as, magnetic field. It has been observed that in the case of permeable boundaries, heat and mass transfer phenomena play a dual in the stability analysis. The flow through porous medium is more stable than the pure flow.
Computational study of ion beam extraction phenomena through multiple apertures
Authors: Hu Wanpeng , Sang Chaofeng , Tang Tengfei , Wang Dezhen , Li Ming , Jin Dazhi , Tan Xiaohua
Published: March 2014

The process of ion extraction through multiple apertures is investigated using a two-dimensional particle-in-cell code. We consider apertures with a fixed diameter with a hydrogen plasma background, and the trajectories of electrons, H+ and H2+ ions in the self-consistently calculated electric field are traced. The focus of this work is the fundamental physics of the ion extraction, and not particular to a specific device. The computed convergence and divergence of the extracted ion beam are analyzed. We find that the extracted ion flux reaching the extraction electrode is non-uniform, and the peak flux positions change according to operational parameters, and do not necessarily match the positions of the apertures in the y-direction. The profile of the ion flux reaching the electrode is mainly affected by the bias voltage and the distance between grid wall and extraction electrode.
Photoluminescence enhancement of the single InAs quantum dots through plasmonic Au island films
Authors: Wang H. Y. , Dou X. M. , Yang Sh. , Su D. , Jiang D. S. , Ni H. Q. , Niu Z. C. , Sun B. Q.
Published: March 2014

The approach of optical positioning the single InAs quantum dots (QDs) was used for investigating QD photoluminescence (PL) enhancement based on plasmonic effect of nanometer-sized Au island films. It is found that the maximum increase of QD PL intensity is about thirty-eight fold after 5-nm thick Au island films are evaporated on the QD sample surface. The enhanced localized excitation field and increased QD radiative decay rate are responsible for this PL enhancement. This provides an alternative way of preparing bright single photon sources based on the plasmonic effect.
Enhancement of thermoelectric performance in InAs nanotubes by tuning quantum confinement effect
Authors: Zhou Wu-Xing , Tan Shihua , Chen Ke-Qiu , Hu Wenping
Published: March 2014

By using the nonequilibrium Green's function method, we study the thermoelectric properties of InAs nanotubes. The results show that InAs nanotube with a certain internal diameter has much higher ZT value than nanowire due to the enhancement of quantum confinement effect leading to the increase of the power factor S2G. The ZT value of InAs nanotube can reach 1.74, which is about three times greater than that of nanowires. Moreover, it is found that the ZT values of InAs nanotubes decrease rapidly with the increase of internal diameter, which results from the rapid increase of phonons thermal conductance due to the “red shift” of low-frequency optical phonon modes.
Thickness-dependent white electroluminescence from diamond/CeF3/SiO2 multilayered films
Authors: Wang Xiaoping , Liu Ping , Wang Lijun , Li Jian
Published: March 2014

Diamond/CeF3/SiO2 multilayered films electroluminescent (EL) devices were made, and we found that the EL spectrum at room temperature depends on the CeF3 layer thickness. The EL spectrum shows that the main peaks are located at 527 nm, 593 nm, and 742 nm when the CeF3 layer thickness is less than 0.5 μm, but when the CeF3 layer thickness is greater than 0.5 μm, the electroluminescence spectrum obviously exhibits three bands, which are centered at 310–380 nm (ultraviolet emission), 520–580 nm (green-yellow emission), and 700–735 nm (red emission). The white EL brightness of the device (for thicker CeF3 layer) reaches a maximum of 15 cd/m2 at a forward applied voltage of 225 V, which can be distinguished at the sunlight in the light by the naked eye.
Investigations on optoelectronic transition mechanisms of silicon nanoporous pillar array by using surface photovoltage spectroscopy and photoluminescence spectroscopy
Authors: Hu Zhen-Gang , Tian Yong-Tao , Li Xin-Jian
Published: March 2014

We report the electronic transition mechanisms for hydrothermally prepared silicon nanoporous pillar array (Si-NPA), investigated by surface photovoltage (SPV) spectroscopy and photoluminescence (PL) spectroscopy. By comparing the SPV spectra of single crystal silicon (sc-Si) with that of Si-NPA, the silicon nano-crystallites (nc-Si)/SiOx nanostructure in the Si-NPA could produce SPV in the wavelength range of 300–580 nm. And 580 nm (∼2.14 eV) was considered as the absorption edge of the nc-Si/SiOx nanostructure. After the sample was annealed and oxidized in air at different temperatures, both the SPV in the wavelength range of 300–580 nm and the PL emission band around 690 nm from the nc-Si/SiOx nanostructure weakened and disappeared as the annealing temperature increased from 100 to 500 °C. But both the red-infrared PL band (>710 nm) and the violet-blue PL band were enhanced by increasing the annealing temperature. After 2 years of natural oxidation in air, the SPV features for sc-Si disappeared completely, and the SPV characteristics of the nc-Si/SiOx nanostructure could be clearly observed. After analysis, the Si–O structure related localized states at the nc-Si/SiOx interface dominated the electronic transitions during the red PL emission and the SPV for the nc-Si/SiOx nanostructure in Si-NPA, the red–infrared PL was due to the Si=O structure related electronic transitions, and the violet-blue PL emission could attribute to the oxygen-related defect related recombination of the photo induced carriers.
Small-displacement measurements using high-order Hermite-Gauss modes
Authors: Sun Hengxin , Liu Kui , Liu Zunlong , Guo Pengliang , Zhang Junxiang , Gao Jiangrui
Published: March 2014

We present a scheme for small-displacement measurements using high-order Hermite-Gauss modes and balanced homodyne detection. We demonstrate its use with experimental results of displacement measurements using fundamental transverse mode TEM00 and first order transverse mode TEM10 as signal modes. The results show a factor of 1.41 improvement in measurement precision with the TEM10 mode compared with that with the TEM00 mode. This scheme has potential applications in precision metrology, atomic force microscopy, and optical imaging.
Identifying the magnetic properties of graphene oxide
Authors: Tang Tao , Liu Fuchi , Liu Yuan , Li Xinyu , Xu Qinghua , Feng Qian , Tang Nujiang , Du Youwei
Published: March 2014

Highly oxidative debris (OD) was obtained by aqueous ammonia wash of as-prepared graphene oxide (GO) which composed of OD and lightly oxidative GO sheets. The magnetic properties of OD and GO were studied. The results showed that OD has a low magnetization of 0.16 emu/g, and the magnetization of GO can be increased from 0.38 to 0.42 emu/g by discarding low-magnetization OD. Thus, this study provided a reliable method to increase the magnetization of GO. Hydroxyl groups were proposed to be the magnetic source.
Electrical switching effect of a single-unit-cell CrO2 layer on rutile TiO2 surface
Authors: Li Si-Da , Liu Bang-Gui
Published: March 2014

Rutile CrO2 is the most important half-metallic material with nearly 100% spin polarization at the Fermi level, and rutile TiO2 is a wide-gap semiconductor with many applications. Here, we show through first-principles investigation that a single-unit-cell CrO2 layer on rutile TiO2 (001) surface is ferromagnetic and semiconductive with a gap of 0.54 eV, and its electronic state transits abruptly to a typical metallic state when an electrical field is applied. Consequently, this makes an interesting electrical switching effect which may be useful in designing spintronic devices.
Sexual health, vulnerabilities and risk behaviours among homeless adults
Authors: Strehlau Verena , Torchalla Iris , Linden Isabelle , Li Kathy , Krausz Michael
Published: March 2014

It is well known that homeless individuals are at risk for a variety of health problems, including sexually transmissible infections. Optimisation of health services for the homeless requires knowledge of their sexual health. The sexual health and sexual vulnerability factors of 500 homeless adults (196 women) were assessed in a cross-sectional survey in three Canadian cities. Our data indicate that a significant proportion of individuals and more women than men reported multiple experiences that compromise their sexual health exponentially. These findings may inform health policies related to sexuality to foster positive sexual health outcomes for all people, including marginalised populations.
Molecular basis for the fold organization and sarcomeric targeting of the muscle atrogin MuRF1
Authors: Franke Barbara , Gasch Alexander , Rodriguez Dayté , Chami Mohamed , Khan Muzamil M. , Rudolf Rüdiger , Bibby Jaclyn , Hanashima Akira , Bogomolovas Julijus , von Castelmur Eleonore , Rigden Daniel J. , Uson Isabel , Labeit Siegfried , Mayans Olga
Published: March 2014

MuRF1 is an E3 ubiquitin ligase central to muscle catabolism. It belongs to the TRIM protein family characterized by a tripartite fold of RING, B-box and coiled-coil (CC) motifs, followed by variable C-terminal domains. The CC motif is hypothesized to be responsible for domain organization in the fold as well as for high-order assembly into functional entities. But data on CC from this family that can clarify the structural significance of this motif are scarce. We have characterized the helical region from MuRF1 and show that, contrary to expectations, its CC domain assembles unproductively, being the B2- and COS-boxes in the fold (respectively flanking the CC) that promote a native quaternary structure. In particular, the C-terminal COS-box seemingly forms an α-hairpin that packs against the CC, influencing its dimerization. This shows that a C-terminal variable domain can be tightly integrated within the conserved TRIM fold to modulate its structure and function. Furthermore, data from transfected muscle show that in MuRF1 the COS-box mediates the
in vivo
targeting of sarcoskeletal structures and points to the pharmacological relevance of the COS domain for treating MuRF1-mediated muscle atrophy.
Nocardioides
opuntiae sp. nov., isolated from soil of a cactus
Authors: Lee Soon Dong , Seong Chi Nam
Published: March 2014

A novel high G+C actinobacterium, designated strain OS1-21T, was isolated from the rhizosphere soil of a cactus (Opuntia fiscus-indica var. sanboten) and the taxonomic status was investigated using a polyphasic approach. Cells of strain OS1-21T were aerobic, Gram-stain-positive, non-endospore-forming, non-motile rods; colonies of the cells were circular, translucent, smooth and moderate yellow in colour. ll-Diaminopimelic acid was the diagnostic diamino acid in cell-wall peptidoglycan. The predominant menaquinone was MK-8(H4). The major fatty acids were iso-C16 : 0, iso-C16 : 0 2-OH, 10-methyl C17 : 0, 10-methyl C18 : 0 and C17 : 1
cis9. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and two unknown phospholipids. The DNA G+C content was 73.7 mol%. Based on 16S rRNA gene sequence analysis, the closest phylogenetic neighbours were

Nocardioides panacihumi

Gsoil 616T (98.7 % sequence similarity) and

Nocardioides terrae

VA15T (97.8 %), followed by

Nocardioides marinus

CL-DD14T (97.1 %). DNA–DNA relatedness values of strain OS1-21T with the type strains of the closest phylogenetic neighbours were low (<16.0 %). Combined data of polyphasic taxonomic analyses revealed that the organism could be assigned to a novel species of the genus

Nocardioides

, for which the name Nocardioides opuntiae sp. nov. is proposed. The type strain is OS1-21T ( = KCTC 19804T = NBRC 107915T).
Comparison of CAGE and RNA-seq transcriptome profiling using clonally amplified and single-molecule next-generation sequencing
Authors: Kawaji Hideya , Lizio Marina , Itoh Masayoshi , Kanamori-Katayama Mutsumi , Kaiho Ai , Nishiyori-Sueki Hiromi , Shin Jay W. , Kojima-Ishiyama Miki , Kawano Mitsuoki , Murata Mitsuyoshi , Ninomiya-Fukuda Noriko , Ishikawa-Kato Sachi , Nagao-Sato Sayaka , Noma Shohei , Hayashizaki Yoshihide , Forrest Alistair R.R. , Carninci Piero ,   The FANTOM Consortium
Published: March 2014

CAGE (cap analysis gene expression) and RNA-seq are two major technologies used to identify transcript abundances as well as structures. They measure expression by sequencing from either the 5′ end of capped molecules (CAGE) or tags randomly distributed along the length of a transcript (RNA-seq). Library protocols for clonally amplified (Illumina, SOLiD, 454 Life Sciences [Roche], Ion Torrent), second-generation sequencing platforms typically employ PCR preamplification prior to clonal amplification, while third-generation, single-molecule sequencers can sequence unamplified libraries. Although these transcriptome profiling platforms have been demonstrated to be individually reproducible, no systematic comparison has been carried out between them. Here we compare CAGE, using both second- and third-generation sequencers, and RNA-seq, using a second-generation sequencer based on a panel of RNA mixtures from two human cell lines to examine power in the discrimination of biological states, detection of differentially expressed genes, linearity of measurements, and quantification reproducibility. We found that the quantified levels of gene expression are largely comparable across platforms and conclude that CAGE and RNA-seq are complementary technologies that can be used to improve incomplete gene models. We also found systematic bias in the second- and third-generation platforms, which is likely due to steps such as linker ligation, cleavage by restriction enzymes, and PCR amplification. This study provides a perspective on the performance of these platforms, which will be a baseline in the design of further experiments to tackle complex transcriptomes uncovered in a wide range of cell types.
Characterization of phase-transition-induced micro-domain structures in vanadium dioxide
Authors: Lu Ping , Zhou Jiadong , Liu Xinling , Zhang Zongtao , Xu Fangfang , Zhang Linlin , Mou Xinliang , Feng Jingwei , Gao Yanfeng , Zhao Jingtai
Published: March 2014

The displacive structural phase transition of vanadium dioxide (VO2) from the high-temperature tetragonal rutile (R) phase to the low-temperature monoclinic M1 or M2 phase may induce the formation of a variety of domain structures. Here, all possible types of phase-transition-induced domain structures of the M1 and M2 phases have been theoretically formulated by using a general space group method. The predicted domain structures of the M1 phase, including mirror or rotation twins and antiphase domains, have been confirmed by transmission electron microscopy observation of VO2powders and films, while the antiphase domains have never been involved in previous studies. The changes undergone by domain structures during a thermal or electron-beam-induced phase transition have been investigated. These results may suggest the potential influence of domain structures on the nucleation and progress of phase transitions, which unambiguously affect the hysteresis behavior of the first-order transition of VO2.
High-temperature Raman spectroscopy of microstructure around the growing β-BaB2O4crystal in the BaO–B2O3–Na2O system
Authors: Liu Shanshan , Zhang Guochun , Wan Songming , Jiang Xingxing , Wang Yuanyuan , Lin Zheshuai , Wu Yicheng
Published: March 2014

High-temperature Raman spectroscopy has been applied to studyin situthe microstructure of the solution near the β-BaB2O4crystal–solution interface in the BaO–B2O3–Na2O growth system. A boundary layer near the crystal–solution interface was observed. In accordance with the high-temperature Raman spectroscopy and first principles calculations, a boron–oxygen structural model is proposed to explain the microstructure of the solution and growth habit. The results show that the growth solution contains a special group, [BO2ØBOØB=O]3−(Ø = bridging oxygen), which transformed to the growth unit [B3O6]3−near the interface.
Crystallographic study of grain refinement of Al by Nb addition
Authors: Wang Feng , Qiu Dong , Liu Zhi-Lin , Taylor John A. , Easton Mark A. , Zhang Ming-Xing
Published: March 2014

The grain refinement of Al by the addition of a small amount of peritectic-forming solute, Nb, has been studied from the crystallographic point of view. Combining the observations of optical microscopy and scanning electron microscopy with the results of energy-dispersive X-ray spectroscopy and X-ray diffraction, it is confirmed that the particles observed at or near the grain centres of refined Al alloys are pro-peritectic Al3Nb particles. The crystallographic matching between the Al3Nb particles and Al grains has also been evaluated using an edge-to-edge matching model and further verified using electron backscatter diffraction and transmission electron microscopy. It is found that there are reproducible crystallographic orientation relationships between the Al3Nb particles and Al grains, and the experimental results are consistent with the predictions of the edge-to-edge matching model. This implies that the pro-peritectic Al3Nb particles are favourable nucleation sites for Al grains from the crystallographic point of view. Furthermore, the analysis of the size distribution of Al3Nb particles reveals that the Al3Nb particles at the grain centres have relatively large particle size, which also corroborates the high potency of Al3Nb according to the free growth model. It is therefore concluded that the significant grain refinement resulting from the addition of Nb is predominantly attributed to thein situformed Al3Nb particles which promote grain refinementviaenhanced heterogeneous nucleation.
Imaging of strain and lattice orientation by quick scanning X-ray microscopy combined with three-dimensional reciprocal space mapping
Authors: Chahine Gilbert André , Richard Marie-Ingrid , Homs-Regojo Roberto Arturo , Tran-Caliste Thu Nhi , Carbone Dina , Jacques Vincent Louis Robert , Grifone Raphael , Boesecke Peter , Katzer Jens , Costina Ioan , Djazouli Hamid , Schroeder Thomas , Schülli Tobias Urs
Published: March 2014

Numerous imaging methods have been developed over recent years in order to study materials at the nanoscale. Within this context, scanning X-ray diffraction microscopy has become a routine technique, giving access to structural properties with sub-micrometre resolution. This article presents an optimized technique and an associated software package which have been implemented at the ID01 beamline (ESRF, Grenoble). A structural scanning probe microscope with intriguing imaging qualities is obtained. The technique consists in a two-dimensional quick continuous mapping with sub-micrometre resolution of a sample at a given reciprocal space position. These real space maps are made by continuously moving the sample while recording scattering images with a fast two-dimensional detector for every point along a rocking curve. Five-dimensional data sets are then produced, consisting of millions of detector images. The images are processed by the user-friendly X-ray strain orientation calculation software (XSOCS), which has been developed at ID01 for automatic analysis. It separates tilt and strain and generates two-dimensional maps of these parameters. At spatial resolutions of typically 200–800 nm, this quick imaging technique achieves strain sensitivity below Δa/a= 10−5and a resolution of tilt variations down to 10−3° over a field of view of 100 × 100 µm.
Managing and improving robot spot welding efficiency: a benchmarking study
Authors: El-Khalil Raed
Published: March 2014

Purpose

– The paper presents a benchmarking analysis that investigates the efficiency gap in relation to spot welding robots in automotive body shops at foreign and domestic companies in North America. The main purpose of this paper is to determine body shop efficiency improvement opportunities for the domestic companies or the Big Three, therefore reducing the competitive gap and improving business performance.

Design/methodology/approach

– The following paper is an extension of an earlier dissertation study conducted by EL-Khalil that focused on improving body shop overall efficiency. The Harbour Report was utilized to determine the best in class facilities that must be visited for benchmarking purposes. The data and information presented were obtained from the facilities visited through observations and interviews. The research utilized the corresponding facilities' labs in order to perform measurements and inspect product welding efficiency. The data obtained were a result of a two-year benchmarking study.

Findings

– The inspection results of spot welds applied on the door flange do not justify the utilization of additional spot welding arm designs and/or robots for the domestic companies. The data presented provide a good opportunity for improving business performance at the body shop Big Three facilities. In order to reduce the current competitive gap, decrease cost, and improve utilization, the Big Three must adopt new strategies (i.e. communization of specific vehicles parts).

Research limitations/implications

– The benchmarking study was limited to the aperture area. Researchers are encouraged to test the propositions further on different types of vehicles and different areas of the vehicle body.

Practical implications

– Based on the actual findings, this paper presents a case that impacts the improvements of the body shop overall performance in relation to reducing the number of spot welding arm and robot designs at the automotive industry in North America.

Originality/value

– The presented gap analysis on body shop spot welding efficiency for automotive companies in North America was not conducted previously. Therefore, the data can be utilized as a benchmark target to drive improvements at the domestic automotive body shops.