bluuebunny/crossref_metadata_2025 huggingface dataset:
Scanning tunneling microscopic and spectroscopic studies on a crystalline silica monolayer epitaxially formed on hexagonal SiC(0001¯) surfaces
Authors: Tochihara Hiroshi , Shirasawa Tetsuroh , Suzuki Takayuki , Miyamachi Toshio , Kajiwara Takashi , Yagyu Kazuma , Yoshizawa Shunsuke , Takahashi Toshio , Tanaka Satoru , Komori Fumio
Published: February 2014

An epitaxial silicon-oxide monolayer of chemical composition of Si2O3 (the Si2O3 layer) formed on hexagonal SiC(0001¯) surfaces has been observed by scanning tunneling microscopy (STM). Filled- and empty-state STM images with atomic resolution support the previously reported model. Typical structural defects in the Si2O3 layer are found to be missing SiOn (n = 1, 2, 3) molecules. The band gap of the Si2O3 layer obtained by point tunneling spectroscopy is 5.5±0.5 eV, exhibiting considerable narrowing from that of bulk SiO2, 8.9 eV. It is proposed that the Si2O3 layer is suitable as a relevant interface material for formation of SiC-based metal-oxide-semiconductor devices.
On equation of state, elastic, and lattice dynamic stability of bcc bismuth under high pressure: Ab-initio calculations
Authors: Mukherjee D. , Sahoo B. D. , Joshi K. D. , Gupta Satish C.
Published: February 2014

First principles calculations have been carried out using density functional theory based Vienna Ab-initio Simulation Package to analyze the elastic and lattice dynamic stability and determine the equation of state of bismuth in bcc phase. The 0 K isotherm has been determined from total energy calculations. The 300 K isotherm obtained after adding thermal corrections to 0 K isotherm compares well with experimental data. The elastic stability of the bcc phase examined from 0 GPa to 220 GPa suggests that this phase is elastically stable throughout this pressure range. The calculated phonon spectra of bcc phase suggest that this phase will be unstable lattice dynamically at ambient pressure but it will attain lattice dynamic stability at ∼8 GPa (the pressure around which this phase gets stabilized energetically). Further, from theoretically calculated elastic moduli, we have derived the volume dependent Gruneisen parameter and used this in Lindemann melting rule to determine the pressure effect on the melting point, i.e., the melting curve. The Hugoniot of bismuth has been generated from 0 K isotherm after adding thermal corrections in conjunction with Rankine-Hugoniot relation. The theoretical Hugoniot and melting curve yielded the shock induced melting pressure to be ∼23.1 GPa with corresponding melting temperature of ∼1333 K, in reasonable agreement with the experimental value of 18–28 GPa.
Acoustic evidence of distinctive temperatures in relaxor-multiferroics
Authors: Smirnova E. , Sotnikov A. , Ktitorov S. , Zaitseva N. , Schmidt H. , Weihnacht M.
Published: February 2014

We present an acoustic study of relaxor ferroelectrics with magnetic ordering PbFexB1−xO3 (B = Nb, Ta, W) in the wide temperature range from 100 to 750 K as well as relaxor PbMg1/3Nb2/3O3 at temperatures from 300 to 750 K. The longitudinal and transverse acoustic wave velocity and attenuation have been measured by the ultrasonic pulse-echo technique at frequencies of 5 and 10 MHz. The strong anomalies observed in the longitudinal sound velocity and attenuation versus temperature are correlated with a temperature range of the coexistence of relaxor ferroelectric and antiferromagnetic states. Attenuation peaks have been observed at distinctive temperatures for relaxors, i.e., at TB (Burns temperature) and T* (an additional distinctive temperature). Fluctuations of the polar nanoregion boundaries are considered as the source of the acoustic anomalies.
Strain enhanced magnetic anisotropy in SmCo/BaTiO3 multiferroic heterostructures
Authors: Moubah R. , Magnus F. , Hjörvarsson B. , Andersson G.
Published: February 2014

We report on the changes in magnetic properties of SmCo/BaTiO3 multiferroic heterostructures as the BaTiO3 substrate undergoes its structural phase transitions. The observations show that the macroscopic magnetization of the SmCo film is affected by the structural phase transitions of the BaTiO3 substrate. Kerr microscopy images show that the magnetic domains of SmCo films have a zigzag shape but their shape is not influenced by the strain transferred from the substrate during the structural phase transitions. Analysis of the magnetoelastic energy shows that the macroscopic change of the magnetization is accompanied by an enhancement of the magnetic anisotropy for the orthorhombic phase of the BaTiO3 substrate and not a change in symmetry of the anisotropy.
Planar graphene tunnel field-effect transistor
Authors: Katkov V. L. , Osipov V. A.
Published: February 2014

We propose a concept for a graphene tunnel field-effect transistor. The main idea is based on the use of two graphene electrodes with zigzag termination divided by a narrow gap under the influence of the common gate. Our analysis shows that such device will have a pronounced switching effect at low gate voltage and high on/off current ratio at room temperature.
Intrinsic and quantitative effects of in-plane strain on ferroelectric properties of Mn-doped BiFeO3 epitaxial films by in situ inducing strain in substrates
Authors: Yang M. M. , Zhao X. Q. , Wang J. , Zhu Q. X. , Zhang J. X. , Li X. M. , Luo H. S. , Li X. G. , Zheng R. K.
Published: February 2014

We report in situ manipulation of the in-plane strain εxx(BFMO) and coercive field EC(BFMO) of BiFe0.95Mn0.05O3 (BFMO) films epitaxially grown on La0.7Sr0.3MnO3 film buffered 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) substrates. PMN-PT poling-induced strain is effectively transferred to BiFe0.95Mn0.05O3 films and enhances εxx(BFMO) and EC(BFMO), with a gauge factor (ΔEC(BFMO)/EC(BFMO))/(δεxx) ∼−25 and −326 for the BFMO(001) and BFMO(111) films, respectively. Based on the strain dependence of EC(BFMO), we established a quantitative relationship between EC(BFMO) and εxx(BFMO). Using ferroelastic strain of PMN-PT, we achieved reversible and non-volatile modulation of strain and EC(BFMO) of BFMO films, providing an approach for non-volatile and reversible turning of strain and physical properties of ferroelectric films.
Manipulation of K center charge states in silicon nitride films to achieve excellent surface passivation for silicon solar cells
Authors: Sharma Vivek , Tracy Clarence , Schroder Dieter , Herasimenka Stanislau , Dauksher William , Bowden Stuart
Published: February 2014

High quality surface passivation (Seff < 5 cm/s) was achieved on polished float zone and textured p- and n-type solar grade Czochralski silicon substrates by externally injecting and storing positive or negative charges (>±8 × 1012 cm−2) into a dual layer stack of Plasma Enhanced Chemical Vapor Deposition (PECVD) Silicon Nitride (SiNx)/PECVD Silicon Oxide (SiO2) films using a corona charging tool. We demonstrate long term stability and uniform charge distribution in the SiNx film by manipulating the charge on K center defects while negating the requirement of a high temperature thermal oxide step.
Antiferroelectricity induced by electric field in NaNbO3-based lead-free ceramics
Authors: Xu Yonghao , Hong Wei , Feng Yujun , Tan Xiaoli
Published: February 2014

Electric fields are known to favor a ferroelectric phase with parallel electric dipoles over an antiferroelectric phase. We demonstrate in this Letter that electric fields can induce an antiferroelectric phase out of a ferroelectric phase in a NaNbO3-based lead-free polycrystalline ceramic. Such an unlikely ferroelectric-to-antiferroelectric phase transition occurs at fields with a reversed polarity and competes with the ferroelectric polarization reversal process.
Note: Practical monitoring system using characteristic impedance measurement during plasma processing
Authors: Motomura T. , Kasashima Y. , Fukuda O. , Uesugi F. , Kurita H. , Kimura N.
Published: February 2014

A method for characteristic impedance monitoring (CIM) is developed for anomaly detection during plasma processing. Advantages of the method include high-sensitivity and real-time monitoring, as well as structural simplicity to install the measurement system in the mass production equipment. To obtain real-time monitoring without time delay, our CIM system consists of a directional coupler and a newly developed vector processing system instead of the conventional high voltage and current probes. The system can measure the time variations of characteristic and load impedances even while the plasma is generated.
Tunable terahertz left-handed metamaterial based on multi-layer graphene-dielectric composite
Authors: Zhu Weiren , Xiao Fajun , Kang Ming , Sikdar Debabrata , Premaratne Malin
Published: February 2014

A terahertz fishnet metamaterial, consisting of a gallium arsenide substrate sandwiched between multi-layer graphene-dielectric composites, is theoretically studied. Detailed analysis shows that this metamaterial has a left-handed transmission peak accompanied with an abnormal phase dispersion and a clear negative refractive index which originates from simultaneous magnetic and electric resonances. Our structure is unique because it has no metallic parts to achieve the left-handed properties. The most important utility of this metamaterial comes from the fact that its left-handed features can be dynamically controlled by applying external bias to shift the Fermi level in graphene.
Spin wave based parallel logic operations for binary data coded with domain walls
Authors: Urazuka Y. , Oyabu S. , Chen H. , Peng B. , Otsuki H. , Tanaka T. , Matsuyama K.
Published: February 2014

We numerically investigate the feasibility of spin wave (SW) based parallel logic operations, where the phase of SW packet (SWP) is exploited as a state variable and the phase shift caused by the interaction with domain wall (DW) is utilized as a logic inversion functionality. A designed functional element consists of parallel ferromagnetic nanowires (6 nm-thick, 36 nm-width, 5120 nm-length, and 200 nm separation) with the perpendicular magnetization and sub-μm scale overlaid conductors. The logic outputs for binary data, coded with the existence (“1”) or absence (“0”) of the DW, are inductively read out from interferometric aspect of the superposed SWPs, one of them propagating through the stored data area. A practical exclusive-or operation, based on 2π periodicity in the phase logic, is demonstrated for the individual nanowire with an order of different output voltage Vout, depending on the logic output for the stored data. The inductive output from the two nanowires exhibits well defined three different signal levels, corresponding to the information distance (Hamming distance) between 2-bit data stored in the multiple nanowires.
Interaction between O2 and ZnO films probed by time-dependent second-harmonic generation
Authors: Andersen S. V. , Vandalon V. , Bosch R. H. E. C. , van de Loo B. W. H. , Pedersen K. , Kessels W. M. M.
Published: February 2014

The interaction between O2 and ZnO thin films prepared by atomic layer deposition has been investigated by time-dependent second-harmonic generation, by probing the electric field induced by adsorbed oxygen molecules on the surface. The second-harmonic generated signal decays upon laser exposure due to two-photon assisted desorption of O2. Blocking and unblocking the laser beam for different time intervals reveals the adsorption rate of O2 onto ZnO. The results demonstrate that electric field induced second-harmonic generation provides a versatile non-contact probe of the adsorption kinetics of molecules on ZnO thin films.
A nuclear physics program at the Rare Isotope Beams Accelerator Facility in Korea
Authors: Moon Chang-Bum
Published: February 2014

This paper outlines the new physics possibilities that fall within the field of nuclear structure and astrophysics based on experiments with radioactive ion beams at the future Rare Isotope Beams Accelerator facility in Korea. This ambitious multi-beam facility has both an Isotope Separation On Line (ISOL) and fragmentation capability to produce rare isotopes beams (RIBs) and will be capable of producing and accelerating beams of wide range mass of nuclides with energies of a few to hundreds MeV per nucleon. The large dynamic range of reaccelerated RIBs will allow the optimization in each nuclear reaction case with respect to cross section and channel opening. The low energy RIBs around Coulomb barrier offer nuclear reactions such as elastic resonance scatterings, one or two particle transfers, Coulomb multiple-excitations, fusion-evaporations, and direct capture reactions for the study of the very neutron-rich and proton-rich nuclides. In contrast, the high energy RIBs produced by in-flight fragmentation with reaccelerated ions from the ISOL enable to explore the study of neutron drip lines in intermediate mass regions. The proposed studies aim at investigating the exotic nuclei near and beyond the nucleon drip lines, and to explore how nuclear many-body systems change in such extreme regions by addressing the following topics: the evolution of shell structure in areas of extreme proton to neutron imbalance; the study of the weak interaction in exotic decay schemes such as beta-delayed two-neutron or two-proton emission; the change of isospin symmetry in isobaric mirror nuclei at the drip lines; two protons or two neutrons radioactivity beyond the drip lines; the role of the continuum states including resonant states above the particle-decay threshold in exotic nuclei; and the effects of nuclear reaction rates triggered by the unbound proton-rich nuclei on nuclear astrophysical processes.
Thickness mapping of high-κ dielectrics at the nanoscale
Authors: Trapnauskas J. , Rommel M. , Bauer A. J. , Frey L.
Published: February 2014

Contact potential difference measurements by Kelvin probe force microscopy (KPFM) together with corona charging was applied for contactless equivalent oxide thickness (EOT) mapping with nanometer range lateral resolution. Characterization was performed under ambient conditions and compared to a conventional macroscale method based on Kelvin probe measurements. The presented method is directly applicable for dielectrics with homogeneous thicknesses. For other dielectric layers, the implemented laboratory setup suffers from imprecise KPFM sample positioning. If such samples have microscopically non-flat surfaces a proposed data evaluation procedure overcomes that issue which is demonstrated for nanoscale EOT maps of HfO2 and HfSixOy samples.
Thermal response of double-layered metal films after ultrashort pulsed laser irradiation: The role of nonthermal electron dynamics
Authors: Tsibidis George D.
Published: February 2014

The thermal response of a Cu-Ti double-layered film is investigated after laser irradiation with ultrashort pulses (pulse duration τp = 50 fs, 800 nm laser wavelength) in submelting conditions by including the influence of nonthermal electrons. A revised two-temperature model is employed to account for the contribution of nonthermal electron distribution while the variation of the optical properties of the material during the laser beam irradiation is also incorporated into the model. Theoretical results can provide significant insight into the physical mechanism that characterize electron dynamics and can facilitate production of controllable ultra-high strength Cu-Ti alloys with promising applications.
Paramagnetic Cu-doped Bi2Te3 nanoplates
Authors: Chen Zhi-Gang , Yang Lei , Ma Song , Cheng Lina , Han Guang , Zhang Zhi-dong , Zou Jin
Published: February 2014

Uniform Cu-doped Bi2Te3 hexagonal nanoplates with widths of ∼200 nm and thicknesses of ∼20 nm were synthesized using a solvothermal method. According to the structural characterization and compositional analysis, the Cu2+ ions were found to substitute Bi3+ ions in the lattice. High-level Cu doping induces a lattice distortion and decreases the crystal lattice by 1.17% in the a axis and 2.38% in the c axis. A paramagnetic state is observed in these nanoplates from 2 to 295 K, which is a significant difference from their diamagnetic un-doped Bi2Te3.
Characterizing transport through a crowded environment with different obstacle sizes
Authors: Ellery Adam J. , Simpson Matthew J. , McCue Scott W. , Baker Ruth E.
Published: February 2014

Transport through crowded environments is often classified as anomalous, rather than classical, Fickian diffusion. Several studies have sought to describe such transport processes using either a continuous time random walk or fractional order differential equation. For both these models the transport is characterized by a parameter α, where α = 1 is associated with Fickian diffusion and α < 1 is associated with anomalous subdiffusion. Here, we simulate a single agent migrating through a crowded environment populated by impenetrable, immobile obstacles and estimate α from mean squared displacement data. We also simulate the transport of a population of such agents through a similar crowded environment and match averaged agent density profiles to the solution of a related fractional order differential equation to obtain an alternative estimate of α. We examine the relationship between our estimate of α and the properties of the obstacle field for both a single agent and a population of agents; we show that in both cases, α decreases as the obstacle density increases, and that the rate of decrease is greater for smaller obstacles. Our work suggests that it may be inappropriate to model transport through a crowded environment using widely reported approaches including power laws to describe the mean squared displacement and fractional order differential equations to represent the averaged agent density profiles.
Plasmonic nanogaps for broadband and large spontaneous emission rate enhancement
Authors: Edwards Anthony P. , Adawi Ali M.
Published: February 2014

We present the optical properties of a plasmonic nanogap formed between a silver metallic nanoparticle and an extended silver film that shows a strong enhancement in the spontaneous emission rate over the whole visible range. In particular, we use three-dimensional finite difference time domain calculations to study the spontaneous emission rate and the quantum efficiency of an emitting material placed within the gap region as a function of the geometrical parameters of the plasmonic nanogap. Our calculations reveal that the enhancements in the total decay rate can be divided into two regions as a function of wavelength; region I spans the wavelength range from 350 nm to 500 nm and peaks at approximately at 400 nm. Region II covers the spectral range between 500 nm and 1000 nm. The enhancements in total decay rate in region I are mainly dominated by Ohmic losses by the metal, while the enhancements in total decay rate in region II are mainly dominated by radiative decay rate enhancements. Furthermore, our calculations show over 100 times enhancement in the spontaneous emission rate in region II. We combine this with quantum efficiency enhancements of almost 30 times from materials with low intrinsic quantum efficiencies and only a small reduction in efficiency from those with high intrinsic quantum efficiencies. All results appear easily achievable using realistic geometrical parameters and simple synthesis techniques. These results are attributed to the strong field confinements in the nanogap region. The structures are of high interest for both the fundamental understanding of light mater interactions under extreme electromagnetic field confinements and also potential applications in quantum optics and Raman spectroscopy.
Dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process
Authors: Ohtori Hiroyuki , Iwano Kaoru , Mitsumata Chiharu , Yano Masao , Kato Akira , Shoji Tetsuya , Manabe Akira , Ono Kanta
Published: February 2014

We analyzed the dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process through visualizing magnetic dipolar interaction. We obtained magnetization distribution images experimentally by using scanning transmission X-ray microscopy (STXM). The magnetic dipolar interaction was calculated by the interaction between the magnetization at each point and those at the other points on the STXM image. We showed the dipolar energy in the nanocrystalline Nd-Fe-B magnets and compared it with the exchange energy at various applied fields. Our results indicated the significance of the dipolar energy in magnetization reversal process.
Enhanced efficiency of the dye-sensitized solar cells by excimer laser irradiated carbon nanotube network counter electrode
Authors: Chien Yun-San , Yang Po-Yu , Lee I-Che , Chu Chih-Chieh , Chou Chia-Hsin , Cheng Huang-Chung , Fu Wei-En
Published: February 2014

The carbon nanotube network decorated with Pt nanoparticles (PtCNT) irradiated by excimer laser as counter electrode (CE) of dye-sensitized solar cells (DSSCs) has been systematically demonstrated. The conversion efficiency would be improved from 7.12% to 9.28% with respect to conventional Pt-film one. It was attributed to the enhanced catalytic surface from Pt nanoparticles and the improved conductivity due to the adjoining phenomenon of PtCNTs irradiated by laser. Moreover, the laser annealing could also promote the interface contact between CE and conductive glass. Therefore, such a simple laser-irradiated PtCNT network is promising for the future flexible DSSCs applications.
Switchable zero-index metamaterials by loading positive-intrinsic-negative diodes
Authors: Xiang Nan , Cheng Qiang , Zhao Jie , Jun Cui Tie , Feng Ma Hui , Xiang Jiang Wei
Published: February 2014

We propose switchable zero-index metamaterials (ZIMs) implemented by split ring resonators (SRRs) loaded with positive-intrinsic-negative (PIN) diode switching elements. We demonstrate that ZIMs can be achieved at around 10 GHz when the PIN diode is switched off. When the PIN diode is switched on, however, the designed metamaterials have impedance matching to the free space, which is useful to reduce the reflections at the interface of two media. The switchable ZIMs are suitable for a wide variety of applications like the beam forming and directive radiation. Experimental results validate the switching ability of the proposed ZIMs.
A four-pixel single-photon pulse-position array fabricated from WSi superconducting nanowire single-photon detectors
Authors: Verma V. B. , Horansky R. , Marsili F. , Stern J. A. , Shaw M. D. , Lita A. E. , Mirin R. P. , Nam S. W.
Published: February 2014

We demonstrate a scalable readout scheme for an infrared single-photon pulse-position camera consisting of WSi superconducting nanowire single-photon detectors. For an N × N array, only 2 × N wires are required to obtain the position of a detection event. As a proof-of-principle, we show results from a 2 × 2 array.
Microscopic reflection difference spectroscopy for strain field of GaN induced by Berkovich nanoindentation
Authors: Gao H. S. , Liu Y. , Zhang H. Y. , Wu S. J. , Jiang C. Y. , Yu J. L. , Zhu L. P. , Li Y. , Huang W. , Chen Y. H.
Published: February 2014

We have measured strain field of Berkovich nanoindentation by Raman mapping technique and microscopic reflection difference spectroscopy (μ-RDS). The validity of the μ-RDS method is verified by the accordance between the theoretical simulated result and the rotated measurement result. Comparing the two different methods, it is concluded that μ-RDS is sensitive and effective to measure anisotropic strain zone in the plane.
Effect of the induced anisotropy axis on altering domain alignment and magnetostriction of Terfenol-D
Authors: Zhang Changsheng , Sun Guangai , Yan Mi , Ma Tianyu
Published: February 2014

The present work investigates quantitatively the effect of induced anisotropy axis on magnetostriction of Terfenol-D, exploring a possible method of tailoring flexibly magnetostriction for a particular purpose. It is found that the induced anisotropy axis shows significant effect on the initial domain state, magnetization process, and thus the magnetostriction. Magnetostriction behaviors for a specific induced anisotropy axis are discussed and compared with the experimental observations. The critical case for the expected 90° domain alignments has been also analyzed quantitatively. Diagrams of domain state evolutions are established, shining some light on understanding magnetostriction tunability and developing magnetostrictive material.
Quantum mechanical solver for confined heterostructure tunnel field-effect transistors
Authors: Verreck Devin , Van de Put Maarten , Sorée Bart , Verhulst Anne S. , Magnus Wim , Vandenberghe William G. , Collaert Nadine , Thean Aaron , Groeseneken Guido
Published: February 2014

Heterostructure tunnel field-effect transistors (HTFET) are promising candidates for low-power applications in future technology nodes, as they are predicted to offer high on-currents, combined with a sub-60 mV/dec subthreshold swing. However, the effects of important quantum mechanical phenomena like size confinement at the heterojunction are not well understood, due to the theoretical and computational difficulties in modeling realistic heterostructures. We therefore present a ballistic quantum transport formalism, combining a novel envelope function approach for semiconductor heterostructures with the multiband quantum transmitting boundary method, which we extend to 2D potentials. We demonstrate an implementation of a 2-band version of the formalism and apply it to study confinement in realistic heterostructure diodes and p-n-i-n HTFETs. For the diodes, both transmission probabilities and current densities are found to decrease with stronger confinement. For the p-n-i-n HTFETs, the improved gate control is found to counteract the deterioration due to confinement.
Single-crystal superconducting nanowires of NbSe2 fabricated by reactive plasma etching
Authors: Mills Shaun A. , Staley Neal E. , Wisser Jacob J. , Shen Chenyi , Xu Zhuan , Liu Ying
Published: February 2014

We present the preparation and measurements of nanowires of single-crystal NbSe2. These nanowires were prepared on ultrathin (≲10 nm) flakes of NbSe2 mechanically exfoliated from a bulk single crystal using a process combining electron beam lithography and reactive plasma etching. The electrical contacts to the nanowires were prepared using Ti/Au. Our technique, which overcomes several limitations of methods developed previously for fabricating superconducting nanowires, also allows for the preparation of complex superconducting nanostructures with a desired geometry. Current-voltage characteristics of individual superconducting single-crystal nanowires with widths down to 30 nm and cross-sectional areas as low as 270 nm2 were measured.
Effects of Al doping on the magnetic properties of ZnCoO and ZnCoO:H
Authors: Park Ji Hun , Lee Seunghun , Kim Bum-Su , Kim Won-Kyung , Chan Cho Yong , Wook Oh Min , Ryong Cho Chae , Jeong Se-Young
Published: February 2014

We investigated the effects of Al doping on ferromagnetism in Co-doped ZnO and the mechanisms that give rise to ferromagnetism in hydrogen-injected ZnCoO. The aim of this study was to determine whether the occurrence of ferromagnetism or the strength of the magnetization is related to the charge carrier mobility, charge carrier density, or the presence of defects in the crystal lattice. Al doping increased the carrier density, as well as the density of oxygen vacancies and the lattice strain; however, these physical properties were not related to the changes in magnetism. Al-doped and undoped ZnCoO showed an increase in ferromagnetism as a function of the hydrogen plasma treatment time. Al doping suppressed the hydrogen-mediated ferromagnetism in ZnCoO:H by trapping hydrogen via oxygen vacancies created by Al doping.
Time-resolved ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer
Authors: Yang Qing , Zhou Xiaohong , Nukui Takao , Saeki Yu , Izumi Sotaro , Tackeuchi Atsushi , Tatsuoka Hirokazu , Liang Shuhua
Published: February 2014

The ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer grown by the thermal oxidation of ZnS with gallium was investigated by the time-resolved photoluminescence as a function of measuring temperature and excitation power. With increase of excitation power, the D0X emission is easily saturated than the DAP emission from ZnO/ZnGa2O4 composite layer, and which is dramatically enhanced as compared with that from pure ZnO layer grown without gallium. The radiative recombination process with ultra-long lifetime controlled the carrier recombination of ZnO/ZnGa2O4 composite layer.
Analytical evaluation of thermal conductance and heat capacities of one-dimensional material systems
Authors: Saygi Salih
Published: February 2014

We theoretically predict some thermal properties versus temperature dependence of one dimensional (1D) material nanowire systems. A known method is used to provide an efficient and reliable analytical procedure for wide temperature range. Predicted formulas are expressed in terms of Bloch-Grüneisen functions and Debye functions. Computing results has proved that the expressions are in excellent agreement with the results reported in the literature even if it is in very low dimension limits of nanowire systems. Therefore the calculation method is a fully predictive approach to calculate thermal conductivity and heat capacities of nanowire material systems.
A new angle on complex dynamics
Authors: Miller Johanna L.
Published: February 2014

Analyzing changes in direction in stochastic trajectories can offer valuable insights.
US taking a hard look at its involvement in ITER
Authors: Kramer David
Published: February 2014

Regulatory uncertainties and an incomplete design are cited in a new review of the US contribution to the seven-party project.
Taking stock of the nanotechnology consumer products market
Authors: Matthews Jermey N. A.
Published: February 2014

A private database in the US invites nanomaterials manufacturers to volunteer their data; similar measures in Europe want that reporting to be mandatory.
Field-scale solute transport parameters derived from tracer tests in large undisturbed soil columns
Authors: Mallants Dirk
Published: February 2014

Transport parameters obtained from laboratory tracer experiments were used to evaluate the stochastic form of the equilibrium convection–dispersion equation (CDE) in describing the transition of scale, i.e. from the column or local scale to a larger field scale. Local-scale solute breakthrough curves (BTCs) were measured in 1-m-long and 0.3-m-diameter undisturbed soil columns by means of time-domain reflectometry at six depths for a 79-h input pulse of chloride. The local-scale data were analysed in terms of the equilibrium CDE and the mobile–immobile non-equilibrium transport model (MIM). At the local scale, the MIM transport model better described the observed early breakthrough and the tailing of the BTC than did the CDE. A linear regression analysis indicated that the relationship between the hydrodynamic dispersion D and pore-water velocity v was of the form D = 31vl.92 (correlation ρv,D = 0.74). Averaging of the local-scale BTCs across the field produced a large-scale or field-scale mean BTC; at the greatest observation depth (0.8 m) the field-scale dispersivity / = λ equals 0.656 m. The results further showed that for large values of the mean dispersion coefficient, , local-scale dispersion is an important mechanism for field-scale solute spreading, whereas the standard deviation, σD, and the correlation between v and D, ρvD, have negligible effects on field-scale transport. Stochastic stream tube models supplemented with statistical properties of local-scale transport parameters provide a practical and computationally efficient tool to describe heterogeneous solute transport at large spatial scales.
Changes in soil C, N and δ15N along three forest–pasture chronosequences in New Zealand
Authors: Mudge P. L. , Schipper L. A. , Baisden W. T. , Ghani A. , Lewis R. W.
Published: February 2014

Changes in total soil carbon (C), nitrogen (N) and natural-abundance N isotopes (δ15N) were measured along three forest-to-pasture chronosequences on pumice soils in the Central North Island of New Zealand. On each of the three chronosequences, exotic pine forests had been converted to intensive dairy pastures 2–11 years before sampling and samples were also taken from remaining pine forests and long-term pastures (40–80 years old). The primary objective of the study was to test the hypothesis that surface-soil δ15N would increase over time following conversion of forest to pasture, due to greater N inputs and isotope-fractionating N losses (e.g. ammonia volatilisation) in pasture systems. Results supported our hypothesis, with linear regression revealing a significant (P < 0.001) positive correlation between log-transformed pasture age (log10[pasture age + 1]) and surface-soil δ15N. There was also a positive correlation (P < 0.001) between pasture age and total soil C and N, and a negative correlation of pasture age with C : N ratio. Surface-soil δ15N was also positively correlated (P < 0.001) with total soil N, and negatively correlated with C : N ratio when C : N was <13.6. These results suggested that as soils became more N-‘saturated’, isotope-fractionating N loss processes increased. Surface-soil δ15N in the pine forests was significantly less than subsoil δ15N, but there was no significant difference between the surface and subsoil in the long-term pastures, due to 15N enrichment of the surface soil. The difference in δ15N between the surface soil and subsoil may be a useful indicator of past land management, in addition to absolute δ15N values of surface soils.
Effects of addition of nitrogen on soil fungal and bacterial biomass and carbon utilisation efficiency in a city lawn soil
Authors: Jiang Xinyu , Cao Lixiang , Zhang Renduo
Published: February 2014

The aim of this study was to investigate the effects of nitrogen (N) addition on soil microbial (fungal and bacterial) biomass and carbon utilisation efficiency (CUE) in a city lawn soil. A field experiment was conducted with three N treatments (kg N ha–1 year–1): the control (0), low-N (100), and high-N (200). Soil biogeochemical properties including pH, C : N, CUE, microbial biomass C (MBC), fungal and bacterial biomass, microbial C uptake rates, and soil respiration (SR) rates were determined during a 500-day experiment. The low- and high-N treatments significantly decreased soil pH, MBC, and CUE. Available N and soil acidification caused a decline in soil MBC. Soil acidification was not beneficial for microbial biomass growth, especially for bacteria. The treatments with N changed soil biomass from bacterial-dominant to fungal-dominant. The results also showed that the CUE of bacterial-dominant soil was higher than that of fungal-dominant soil, which is contrary to previous studies. However, SR did not increase with decreased CUE under N treatments, because the addition of N limited soil microbial C uptake rates and significantly decreased soil microbial biomass. The CUE showed a negative correlation with soil temperature for the control treatment but not for the N treatments, which suggested that added N played a more important role in CUE than did soil temperature. Our results showed that addition of further N significantly alters soil biogeochemical properties, alters the ratio of bacteria to fungi, and decreases microbial carbon utilisation, which should provide important information for model-based prediction of soil C-cycling.
Transcriptional activation of hypoxia-inducible factor-1 (HIF-1) in myeloid cells promotes angiogenesis through VEGF and S100A8
Authors: Ahn G-One , Seita Jun , Hong Beom-Ju , Kim Young-Eun , Bok Seoyeon , Lee Chan-Ju , Kim Kwang Soon , Lee Jerry C. , Leeper Nicholas J. , Cooke John P. , Kim Hak Jae , Kim Il Han , Weissman Irving L. , Brown J. Martin
Published: February 2014

Significance

Here, we are reporting our findings that hypoxia-inducible factor 1 (HIF-1) activation in monocytes promotes neovascularization in matrigel and improves blood flow in hindlimb ischemia through production of vascular endothelial growth factor and S100A8. We found that HIF-1 regulates S100A8 expression specifically in monocytes isolated from our unique strain of transgenic mice targeting HIF pathways.
Arabidopsis JAGGED links floral organ patterning to tissue growth by repressing Kip-related cell cycle inhibitors
Authors: Schiessl Katharina , Muiño Jose M. , Sablowski Robert
Published: February 2014

Significance

Plant organs, such as leaves, petals, or fruits, are shaped by the behavior of their constituent cells: cell growth, oriented extension of cell walls, and cell division. However, we know little about how these processes are coordinated by regulatory genes that shape plant organs, such as
JAGGED
(
JAG
) in
Arabidopsis
. By identifying the genes bound by JAG throughout the genome and the consequent changes in gene expression, we reveal that
JAG
functions as a direct mediator between genes that control the identity of organs and tissues and the cellular activities required for organ growth. In particular, we show that
JAG
sculpts floral organs by directly repressing genes that control entry into DNA replication.
Social movements of the historical Indian Diaspora in South Africa: binding the ‘home’ and ‘homeland’ creatively?
Authors: Sinha Bobby Luthra
Published: February 2014

India and South Africa are strongly bonded to each other not just as member nations of BRICS1 that confirms their status as prominently upcoming and emerging markets of the contemporary world, but also as associates of a mutually shared and entangled history from colonial times. The migration of the Indian Diaspora to South Africa from 1860 onwards, its eventual struggle for dignity against racial discrimination and participation in the national liberation movement have been a matter of pride to India in the past. But it is little known that the people of Indian origin have also organized themselves for community welfare and more recently organized themselves in Heritage Movements (HMs) to raise issues important for them socially as well as symbolically in the their past and contemporary history. How do they relate to India through them and what do they think of India? While bilateral economic ties between today’s South Africa and India dominate the spheres of political imagination, interestingly, we see that over the years, the Indian foreign policy is undergoing a ‘Diaspora moment’ in various aspects. This paper, therefore, attempts to understand the Diaspora more closely under this background of mutual relations and shifts the focus to the collective action of the common Indian South Africans (ISAs) on ground and to their imagination of India and Indianness. We will use examples from social movements (SMs) of the ISAs as an analytical template for seeing the extent to which Diaspora can be used as a conceptual tool in understanding the changing meaning of Indianness in South Africa and conversely what message does it hold for India? Relevant instances of the politics of community selfhelp and HMs among the Durban/KwaZulu-Natal Indians in South Africa will be analysed and official opinions on Diaspora (etic views) will be juxtaposed with voices of these actors from the field (emic views). Observing the narratives of the SMs of the ISAs closely, we gain an insight into the following facts that can become an important input in sensitizing India’s foreign policy with reference to its historic Diaspora in South Africa: firstly, its ongoing need, even in the post-apartheid era, for gaining contextual legitimacy and space in the process of nation building in the new South Africa. Secondly, though the ISAs are proud of their historical ties and cultural legacies with India, their position and identity within the broader political system of South Africa goes beyond their imagined ‘Indianness’. Thirdly, while their role in collective socio-cultural and political engagements make them a credible and vibrant Diaspora of which India can be proud of, nonetheless, the actors in the field emphasize that only when seen as indispensable asset of South Africa can they open up and build their mutual relations with India to newer heights.
The African Court of Justice and Human Rights: the future of international criminal justice in Africa
Authors: Agwu Fred Aja
Published: February 2014

The decision by the African Union to imbue the African Court on Human Rights with criminal jurisdiction smacks of confrontation with the international community because some of their member states are parties to the Rome Statute that created the International Criminal Court (ICC). The effort is an unnecessary duplication that can only at best give soft landing or shield tyrannical African leaders from international accountability for their well-known impunity. The decision also underestimates the challenges in the onerous task of achieving international justice from a narrow African regional platform where conspiracy and collusion to undermine justice may be rife. The fact is that ‘… the doubts must always remain that the political passions involved might overrule the formal exigencies of a regular criminal trial …. The path from the opening of a mass grave to proving a political leader responsible is long and complex, and success is by no means ensured’ [Thakur, R., and P. Malcontent., ed. 2004. From Sovereign Impunity to International Accountability: The Search for Justice in a World of States. Tokyo: United Nations University Press, xv–xvi].
AMASS: a database for investigating protein structures
Authors: Mielke Clinton J. , Mandarino Lawrence J. , Dinu Valentin
Published: February 2014

Motivation: Modern techniques have produced many sequence annotation databases and protein structure portals, but these Web resources are rarely integrated in ways that permit straightforward exploration of protein functional residues and their co-localization.

Results: We have created the AMASS database, which maps 1D sequence annotation databases to 3D protein structures with an intuitive visualization interface. Our platform also provides an analysis service that screens mass spectrometry sequence data for post-translational modifications that reside in functionally relevant locations within protein structures. The system is built on the premise that functional residues such as active sites, cancer mutations and post-translational modifications within proteins may co-localize and share common functions.

Availability and implementation: AMASS database is implemented with Biopython and Apache as a freely available Web server at amass-db.org.

Contact:  clinton.mielke@gmail.com
Linking spatial stock dynamics and economics: evaluation of indicators and fishery management for the travelling eastern king prawn (Melicertus plebejus)
Authors: O'Neill Michael F. , Leigh George M. , Wang You-Gan , Braccini J. Matías , Ives Matthew C.
Published: February 2014

Reduced economic circumstances have moved management goals towards higher profit, rather than maximum sustainable yields in several Australian fisheries. The eastern king prawn is one such fishery, for which we have developed new methodology for stock dynamics, calculation of model-based and data-based reference points and management strategy evaluation. The fishery is notable for the northward movement of prawns in eastern Australian waters, from the State jurisdiction of New South Wales to that of Queensland, as they grow to spawning size, so that vessels fishing in the northern deeper waters harvest more large prawns. Bioeconomic fishing data were standardized for calibrating a length-structured spatial operating model. Model simulations identified that reduced boat numbers and fishing effort could improve profitability while retaining viable fishing in each jurisdiction. Simulations also identified catch rate levels that were effective for monitoring in simple within-year effort-control rules. However, favourable performance of catch rate indicators was achieved only when a meaningful upper limit was placed on total allowed fishing effort. The methods and findings will allow improved measures for monitoring fisheries and inform decision makers on the uncertainty and assumptions affecting economic indicators.
Evaluation of determinants of Xiphopenaeus kroyeri (Heller, 1862) catch abundance along a Southwest Atlantic subtropical shelf
Authors: Kolling Juliana Almeida , Ávila-da-Silva Antônio Olinto
Published: February 2014

Generalized linear models were applied to identify factors affecting the capture rates (catch per unit effort, cpue) of Xiphopenaeus kroyeri and to estimate time-series data with standardized abundance indices. The adjusted models revealed that the most powerful vessels (with greater HP) were up to 3.5 times more efficient than vessels with less powerful engines. The seasonal variation of the resource changed from year to year, most likely due to variations in the recruitment season and the timing of temporary fishing bans. The variation of cpue was similar between the northern and southern sectors of the study area. In these, X. kroyeri abundances increased in the years 1996, 1997, 2001 and 2002, while in the central sector, the cpue fluctuated with a period duration of approximately two years. During the period, the relative abundance of the species displayed neither a decreasing nor an increasing trend, indicating that this has been harvested at stable levels. However, X. kroyeri stock was reduced by overfishing during the 1980s and exhibits variations in abundance that may occur in response to environmental fluctuations; thus, the harvesting of this species should be managed with extreme caution.
B-CLL cells acquire APC- and CTL-like phenotypic characteristics after stimulation with CpG ODN and IL-21
Authors: Hagn Magdalena , Blackwell Sue E. , Beyer Thamara , Ebel Verena , Fabricius Dorit , Lindner Stefanie , Stilgenbauer Stefan , Simmet Thomas , Tam Constantine , Neeson Paul , Trapani Joseph A. , Schrezenmeier Hubert , Weiner George J. , Jahrsdörfer Bernd
Published: February 2014

CpG oligodeoxynucleotides (CpG) and IL-21 are two promising agents for the treatment of B-cell chronic lymphocytic leukemia (B-CLL). Recently, we reported that the combination of CpG and IL-21 (CpG/IL-21) can induce granzyme B (GrB)-dependent apoptosis in B-CLL cells. Here, we demonstrate that treatment of B-CLL cells with CpG and IL-21 results in the development of antigen-presenting cell (APC)-like cells with cytotoxic features. These properties eventually give rise to B-CLL cell apoptosis, independently of their cytogenetic phenotype, whereas normal B-cell survival is not negatively affected by CpG/IL-21. APC- and CTL-typical molecules found to be up-regulated in CpG/IL-21-stimulated B-CLL cells include GrB, perforin, T-bet, monokine-induced by IFN-γ and IFN-γ-inducible protein 10 (IP-10), as well as molecules important for cell adhesion, antigen cross-presentation and costimulation. Also induced are molecules involved in GrB induction, trafficking and processing, whereas the GrB inhibitor Serpin B9 [formerly proteinase inhibitor-9 (PI-9)] is down-modulated by CpG/IL-21. In conclusion, CpG/IL-21-stimulated B-CLL cells acquire features that are reminiscent of killer dendritic cells, and which result in enhanced immunogenicity, cytotoxicity and apoptosis. Our results provide novel insights into the aberrant immune state of B-CLL cells and may establish a basis for the development of an innovative cellular vaccination approach in B-CLL.
The Psychological Foundations of Human Rights
Authors: Kar Robin Bradley
Published: February 2014

This article examines the role of psychology in the historical foundation of human rights. It provides an account of the psychological capacities that humans use to identify and respond to rights and analyses the distinctive ways that humans reason about rights. It also discusses the basic psychology of rights and obligations and considers the place of the psychology of rights and obligations in a contemporary evolutionary framework. This article argues that while humans have an innate psychological capacity to identify and respond to rights, the more specific phenomenon of respect for human rights is at least in part a culturally emergent phenomenon.