bluuebunny/crossref_metadata_2025 huggingface dataset:
A quasi‐decadal cycle in Caribbean climate
Authors: Jury Mark R.
Published: July 2009

Climatic variables in the period from 1951 to 2000 are analyzed across the tropics from the East Pacific to Africa. A quasi‐decadal mode is isolated using singular value decomposition (SVD) applied to monthly smoothed and detrended rainfall, sea surface temperature (SST), sea level pressure (SLP), and 200 hPa zonal (U) wind anomalies. Seven‐ to 10‐year cycles in Caribbean rainfall are revealed as the dominant mode (50% variance) and are found to be related to a mode of tropical variability that is distinct from previously known global signals. Sources of this signal include east Atlantic SST and the northern subtropical ridge, which modulate upwelling off Venezuela. SVD analysis of daily rainfall suggests interaction between annual and quasi‐decadal signals, with northern summer convection as a driver. The second mode of Caribbean rainfall variability derives from the east Pacific El Niño Southern Oscillation (ENSO, 21% variance) that is expressed as an east‐west dipole of convection across the Caribbean. Composite analysis of rainfall for high and low phases of the quasi‐decadal cycle reveals a corresponding signal that extends from the eastern Pacific Ocean across the Caribbean and West Africa to India. The southern Hadley cell spins up during wet phase, and the ITCZ migrates northward. This hemispheric‐scale anomaly brings pulses of convection to the Caribbean. Impacts of the quasi‐decadal cycle on socioeconomic resources are investigated.
Association between Regional Cerebral Blood Flow during Hypoglycemia and Genetic and Phenotypic Traits of the Renin–Angiotensin System
Authors: Bie-Olsen Lise Grimmeshave , Pedersen-Bjergaard Ulrik , Kjær Troels Wesenberg , Lonsdale Markus Nowak , Law Ian , Thorsteinsson Birger
Published: July 2009

The risk of severe hypoglycemia in patients with type I diabetes and high basal activity in the renin–angiotensin system (RAS) is significantly higher than in patients with low basal RAS activity. In healthy men, we tested the hypothesis that differences in spontaneous RAS activity are associated with differences in cerebral activity responses during mild hypoglycemia. A total of 10 healthy men with high and 10 with low spontaneous RAS activity were selected. An H215O-PET (H215O-positron emission tomography) study was conducted with a series of six scans, i.e., two during normoglycemia, two during hypoglycemia, and two after hypoglycemia. The mean plasma glucose concentration was similar in both the groups (i.e., 2.1 mmol/L (s.d.: 0.4) in the low RAS group and 2.2 mmol/L (s.d.: 0.4) in the high RAS group ( P=0.47)). The high RAS group has lower cerebral activity in the frontal area and a higher cerebral activity in the entorhinal area that expanded to include the parahippocampal gyrus after hypoglycemia. Our findings suggest that the high RAS group to a lesser extent than the low RAS group activates areas involving executive function that may explain the correlation between high basal RAS activity and risk of severe hypoglycemia in type I diabetes.
Cervical Cancer-Associated Human Papillomavirus 16 E7 Oncoprotein Inhibits Induction of Anti-Cancer Immunity by a CD4+ T Cell Dependent Mechanism
Authors: Brunck Marion , Liu Xiao Song , Zhong Jie , Fernando Germain
Published: July 2009

Attempts to develop therapeutic vaccines against cervical cancer have been proven difficult. One of the major causes of the failure is due to the use of the wrong mouse models based on transplantable tumours in testing the efficacy of vaccines. Now that a transgenic epithelial mouse model has been developed to closely mimic cervical cancer, the mechanisms needed to eliminate this type of cancer could be studied. The E7 oncoprotein of Human Papillomavirus (HPV) is the most expressed HPV protein in cervical cancers and its continuous production is essential to maintain the cancerous state and therefore the obvious target in the development of vaccines. Skin grafts expressing the HPV 16 E7 protein (E7 autografts) are not spontaneously rejected from an MHC matched immunocompetent host. Interestingly, simultaneous placement of an MHC mismatched skin (allograft) next to an E7 autograft results in the E7 autograft rejection. However when the allograft also expresses E7, the E7 autograft is rejected more slowly. Autograft rejection requires CD8+ T cells, and is accelerated by removal of CD4+ T cells after placement of the E7 expressing allograft, suggesting induction of an E7 specific CD4+ regulatory T cell population by the E7 expressing allograft. This observation may have implications in designing effective vaccines and immunotherapy against cervical cancers in women.
Microwave-Assisted Proteomics
Authors: Lill Jennie R
Published: July 2009

Since the conceptualization of the electromagnetic spectrum and development of the magnetron, microwave energy has been utilized in many aspects and disciplines of science. Although adopted by multiple industries over the past quarter of a century, it is only within the past few years that microwave irradiation has been evaluated as a useful tool for the biochemical and chemical preparation of proteins and other bio-molecules for proteomics and in particular mass spectrometric analysis. This book is an introduction to microwave-assisted bio-analytical methods with an emphasis on sample preparation for proteomic analyses. Its objective is to provide a history and background for the methods described and the book summarizes the development and application of these protocols from both the literature in this field as well as from the experiences of a variety of laboratories conducting microwave-assisted protocols. It describes the evolution and integration of microwave energy into the biosciences with particular emphasis on the proteomic arena and an in depth evaluation of a variety of techniques within the field of proteomics which benefit from microwave-irradiation is given. In addition to describing the evolution of the microwave-assisted methodologies, the book also offers a concise protocol section with practical advice on how to implement these methods in any laboratory. Mechanisms of action as well as an overview of the types of instrumentation available are described to help the reader develop the best experimental design for their own budget and experimental aims. Microwave-assisted proteomics is a rapidly evolving field and this book captures the main areas that fall under this emerging arena.
Wind energy in India: Status and future prospects
Authors: Purohit Ishan , Purohit Pallav
Published: July 2009

Wind energy, with an average growth rate of 30%, is the fastest growing source of renewable energy in the world. India occupies the fifth place in the world in wind energy generation after USA, Germany, Spain, and China and has an installed capacity of more than 9756 MW as of January 31, 2009. New technological developments in wind energy design have contributed to the significant advances in wind energy penetration and to get optimum power from available wind. In this study, an attempt has been made to analyze and review the development and dissemination of wind energy in India. The diffusion prospect of wind energy generation in the potential states of India is also analyzed.
Optoacoustic method for determination of submicron metal coating properties: Theoretical consideration
Authors: Pelivanov Ivan M. , Kopylova Daria S. , Podymova Natalia B. , Karabutov Alexander A.
Published: July 2009

The goal of this work is theoretical consideration of the optoacoustic (OA) conversion in the system consisting of a metal film deposited on a transparent dielectric substrate and covered by a transparent liquid. This consideration implies a method for nondestructive evaluation of submicron metal coatings. The main principle of the method is the following. Irradiation of the metal film by a nanosecond laser pulse leads to transient heating and expansion of the film that in turn results in the generation of an acoustic signal. The waveform of the signal results from two contributions: the “primary” signal from the thermal expansion of the metal film, which repeats the temporal profile of the laser pulse envelope, and the “secondary” signal, which originates from the thermal expansion of the adjacent liquid layer. Due to low thermal conductivity of liquid compared to metal, the liquid accumulates heat that is released in metal and produces that secondary contribution into the OA conversion. This contribution is very sensitive to the properties of the film. The influence of the film thickness and its thermophysical parameters on the frequency-dependent efficiency of OA conversion and on the temporal profile of excited OA signals is discussed in detail. Based on these results, the method for nondestructive evaluation of submicron metal coatings properties is proposed.
Interfacial defects in resistive switching devices probed by thermal analysis
Authors: Lau H. K. , Leung C. W. , Hu W. H. , Chan P. K. L.
Published: July 2009

Resistive switching mechanism is investigated by thermal analysis of metal electrodes in the planar Al/Pr0.7Ca0.3MnO3(PCMO)/Ni resistive switching device geometry. Two microthermocouples are used to monitor the electrode temperatures under different electrical bias conditions. Comparison of temperature differences between Al and Ni electrodes at high and low resistance states suggests that local heat source exists under the Al electrode at high resistance state. It agrees well with the recent finding in which AlOx presents at the Al/PCMO interface and it can be the origin of the resistance switching mechanism [Li et al., J. Phys. D 42, 045411 (2009)]. Thermal measurements demonstrate excellent capability on characterizing resistance switching devices.
Fast, spatially resolved thermometry of Si and GaP crystals using pump-probe two-photon absorption
Authors: Min Chang-Ki , Park Ji Yong , Cahill David G. , Granick Steve
Published: July 2009

Noncontact thermometry with micron-scale lateral spatial resolution and fast time resolution is shown to be enabled by measuring the temperature dependence of two-photon absorption (TPA) on crystalline semiconductors. In the proof-of-concept experiments reported here, for studies of Si, an Er:fiber laser at λ=1.56 μm is split into pump and probe beams; where they overlap, the large TPA signal changes strongly with temperature because the two-photon energy lies between the indirect and direct bandgaps of Si. We show that the TPA coefficient increases by a factor of 2 when the temperature increases from 30 to 300 °C. For studies of GaP, we use instead a Ti:sapphire laser at 790 nm to achieve two-photon excitation above the direct bandgap. In GaP, contributions to the TPA from the dominant direct transition show less temperature dependence than for Si but the additional contribution of the indirect transition gives a similar magnitude as the temperature dependence of TPA on Si. In the current implementation using Si, the spatial resolution of the thermometry is 6×6×50 μm3 and the sensitivity is 0.6 K in a 1 kHz bandwidth.
The effect of dust size distribution on envelope wave packet in magnetized two-temperature-ion dusty plasma
Authors: Lin Mai-mai , Duan Wen-shan
Published: July 2009

The effect of arbitrary dust size distribution on a nonlinear envelope wave packet in a magnetized two-temperature-ion dusty plasma has been studied in this paper. By using the reductive perturbation method, the dispersion relation and a (3+1)-dimensional nonlinear Schrödinger equation (NLSE) have been obtained. It is found that the frequency, the group velocity, and the propagation behavior of the envelope waves have been significantly influenced by different dust size distributions. It is also found that the frequency increases as the total number density of dust particles increases. Moreover, it seems that the frequency for usual dusty plasma is smaller than that of the unusual case. On the other hand, the modulational instability of envelope waves has also been discussed by analyzing the solution of the NLSE. It is shown that the conditions of modulational instability for envelope waves are different for various cases.
Long cycles in the infinite-range-hopping Bose–Hubbard model
Authors: Boland G.
Published: July 2009

In this paper we study the relation between long cycles and Bose–Einstein condensation in the infinite-range Bose–Hubbard model. We obtain an expression for the cycle density involving the partition function for a Bose–Hubbard Hamiltonian with a single-site correction. Inspired by the approximating Hamiltonian method we conjecture a simplified expression for the short cycle density as a ratio of single-site partition functions. In the absence of condensation we prove that this simplification is exact and use it to show that in this case the long cycle density vanishes. In the presence of condensation we can justify this simplification when a gauge-symmetry breaking term is introduced in the Hamiltonian. Assuming our conjecture is correct, we compare numerically the long cycle density with the condensate and find that although they coexist, in general, they are not equal.
Selectively enhanced emission and suppression in Si0.5Ge0.5/Si multiple quantum wells by photonic crystals
Authors: Wei C. M. , Chen T. T. , Chen C. W. , Wang C. H. , Chen Y. F. , Peng Y. H. , Kuan C. H.
Published: July 2009

Selective enhancement and suppression of the photoluminescence arising from Si0.5Ge0.5/Si multiple quantum wells by photonic crystals (PCs) have been demonstrated. The formation of the stop band in PCs is designed to be a filter as well as a reflector. It is found that the self-assembled PCs are able to selectively enhance the luminescence of the type-II transitions at the interface between Si and Si0.5Ge0.5/Si layers and suppress the emission from Si. Our working principle shown here can be extended to many other material systems and should be very useful for creating high power solid-state emitters.
X-ray diffraction of MgxZn1−xO and ZnO nanocrystals under high pressure
Authors: Zhuravlev K. K. , Hlaing Oo W. M. , McCluskey M. D. , Huso J. , Morrison J. L. , Bergman L.
Published: July 2009

Mg x Zn 1 − x O  (x=0.15) and ZnO nanocrystals of about 40 nm in diameter were studied using x-ray diffraction and diamond-anvil cells. The equation of state (EOS) for MgZnO is reported for the first time. Between pressures of 9.45 and 10.7 GPa, MgZnO transforms into the rocksalt (NaCl) structure, which persisted to 1.1 GPa upon decompression. The EOS parameters for ZnO are close to their bulk values and in good agreement with values obtained previously. The bulk modulus for MgZnO was slightly lower than that of ZnO. The pressure-induced decrease in c/a ratio was greater for MgZnO, consistent with the tendency for MgZnO to move toward a cubic structure. From previous photoluminescence measurements [J. Huso et al., Appl. Phys. Lett. 89, 171909 (2006)], the band-gap volume deformation potentials for ZnO and Mg0.15Zn0.85O were determined to be −3.6 and −4.0 eV, respectively.
Ethene stabilization on Cu(111) by surface roughness
Authors: Skibbe Olaf , Vogel Diana , Binder Martin , Pucci Annemarie , Kravchuk Tatyana , Vattuone Luca , Venugopal Vinay , Kokalj Anton , Rocca Mario
Published: July 2009

The molecular vibrations of ethene adsorbed on roughened Cu(111) surfaces have been investigated with high resolution electron energy loss spectroscopy and density-functional-theory calculations. The roughness was introduced by sputtering or evaporation of copper, respectively, on the cooled surface. We found stabilization of the ethene layer compared to ethene adsorbed on pristine Cu(111). Furthermore, two new vibrational features observed on the rough surface can be assigned to frustrated translations and rotations of the ethene molecule on surface defects and are indicative of a different binding on the rough surface.
Effect of decamethylcyclopentasiloxane and trifluoromethane electron cyclotron resonance plasmas on F–SiCOH low dielectric constant film deposition
Authors: Ye Chao , Zhang Haiyan , Ning Zhaoyuan
Published: July 2009

The characteristics of decamethylcyclopentasiloxane (DMCPS) and trifluoromethane (CHF3) electron cyclotron resonance plasmas for depositing F–SiCOH low dielectric constant films were investigated by quadrupole mass spectrometry and optical emission spectroscopy. The radicals in the plasma come from the dissociation of DMCPS and CHF3 molecules and the recombination of active radicals. The DMCPS dissociation produced the Si-related and CH-related radicals, including the SiOC2H5, SiOCH3, SiCH3, SiO, Si, O, CH3, CH2, CH, C, and H radicals, by breaking the Si–O fivefold ring and Si–O chain and by removing hydrocarbon groups from Si atoms. The CHF3 dissociation produced the F-related radicals, including the CHF2, CF3, and F radicals. The recombination of active radicals produced the HF, C2H2, C2H3, C2H4, C2H5, C2, H2, SiH2, SiF3, SiF2, and SiF radicals. The Si-related and CH-related radicals led to the deposition of SiCOH films; however, the F-related radicals led not only to the deposition of F–SiCOH films but also to the etching of SiCOH films by the reactions between F and Si atoms in the plasma and at the surface of as-deposited films simultaneously. The competition between film deposition and etching led to an n-type dependence of the deposition rate on CHF3/DMCPS flow rate ratio, the drastic composition change, and the structural evolution from SiCOH to Si-doping COF and further to COF films.
Impurity scattering induced excitonic polariton damping and its influence on the reflectance spectra of GaN epilayers
Authors: Wang Y. J. , Wang R. X. , Li G. Q. , Xu S. J.
Published: July 2009

The low-temperature reflectance spectra of a number of GaN epilayers with various impurity/defect concentrations and Hall mobility are systematically investigated in this paper. The interacting excitonic polariton model, considering both excitons A and B, is employed to reproduce the measured reflectance spectra of the GaN films, leading to the determination of the damping coefficients of the propagating polaritons in the films. It is shown that the impurity scattering plays a dominant role in the damping of the excitonic polaritons in the GaN epilayers with higher impurity concentrations at low temperatures, which is additionally supported by the photoluminescence and Hall measurements.
Liquid mercury sound velocity measurements under high pressure and high temperature by picosecond acoustics in a diamond anvils cell
Authors: Decremps F. , Belliard L. , Couzinet B. , Vincent S. , Munsch P. , Le Marchand G. , Perrin B.
Published: July 2009

Recent improvements to measure ultrasonic sound velocities of liquids under extreme conditions are described. Principle and feasibility of picosecond acoustics in liquids embedded in a diamond anvils cell are given. To illustrate the capability of these advances in the sound velocity measurement technique, original high pressure and high temperature results on the sound velocity of liquid mercury up to 5 GPa and 575 K are given. This high pressure technique will certainly be useful in several fundamental and applied problems in physics and many other fields such as geophysics, nonlinear acoustics, underwater sound, petrology or physical acoustics.
Temperature dependence of the optical properties of AlInN
Authors: Jiang L. F. , Shen W. Z. , Guo Q. X.
Published: July 2009

Measurements of the temperature dependence of transmission have been carried out on AlInN thin films grown by reactive radio-frequency magnetron sputtering on (0001) sapphire substrates. By following a detailed procedure developed for analyzing the transmission spectra, we obtained more reliable data for the effects of temperature on the optical properties of AlInN. Two sets of temperature and photon-energy dependence of empirical formulas have been established for the absorption coefficient, bandgap, Urbach bandtail, and refractive index, which not only unify various experimental data reported in the literature but also provide a database of the optical properties of AlInN based on experimental results. It was found that the shift in the temperature dependence of the bandgap increases with the Al content and that the Urbach bandtail parameter is closely related to the structural characteristics of the AlInN thin films. These optical properties provide an experimental basis for further theoretical investigation and the design of AlInN-based devices.
Measurement of photoionization cross sections of the excited states of titanium, cobalt, and nickel
Authors: Cong Ran , Cheng Yi , Yang Jiajun , Fan Jianmei , Yao Guanxin , Ji Xuehan , Zheng Xianfeng , Cui Zhifeng
Published: July 2009

Resonance-enhanced multiphoton ionization (REMPI) of Ti, Co, and Ni atoms has been investigated in the 285–320 nm region. We couple a laser-ablated metal target into a molecular beam to produce atoms. Ions produced from photoionization of the neutral atoms are monitored by a home-built time-of-flight mass spectrometer. Photoionization cross sections of the excited states of Ti, Co, and Ni were deduced from the dependence of the ion signal intensity on the laser intensity for photon energies close to the ionization threshold. The values obtained range from 0.2 to 6.0 Mb. No significant isotope dependence was found from measurements of the photoionization cross sections of T46i, T47i, T48i, N58i, and N60i.
Simplified model of nonlinear Landau damping
Authors: Yampolsky N. A. , Fisch N. J.
Published: July 2009

The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.
Isotropic periodic sum of electrostatic interactions for polar systems
Authors: Wu Xiongwu , Brooks Bernard R.
Published: July 2009

Isotropic periodic sum (IPS) is a method to calculate long-range interactions based on homogeneity of simulation systems. Long-range interactions are represented by interactions with isotropic periodic images of a defined local region and can be reduced to short ranged IPS potentials. The original electrostatic three-dimensional (3D)-IPS potential was derived based on a nonpolar homogeneous approximation and its application is limited to nonpolar or weak polar systems. This work derived a polar electrostatic 3D-IPS potential based on polar interactions. For the convenience of application, polynomial functions with rationalized coefficients are proposed for electrostatic and Lennard-Jones 3D-IPS potentials. Model systems of various polarities and several commonly used solvent systems are simulated to evaluate the 3D-IPS potentials. It is demonstrated that for polar systems the polar electrostatic 3D-IPS potential has much improved accuracy as compared to the nonpolar 3D-IPS potential. For homogeneous systems, the polar electrostatic 3D-IPS potential with a local region radius or cutoff distance of as small as 10 Å can satisfactorily reproduce energetic, structural, and dynamic properties from the particle-meshed-Ewald method. For both homogeneous and heterogeneous systems, the 3D-IPS/discrete fast Fourier transform method using either the nonpolar or the polar electrostatic 3D-IPS potentials results in very similar simulation results.
Hybrid quantitative simulation on the in-line phase-contrast x-ray imaging of three dimensional samples under actual clinic imaging parameters
Authors: Yu Hong , Han Shensheng , Ding Jianhui , Jiang Zhaoxia , Peng Weijun
Published: July 2009

A hybrid model combining Monte Carlo method with diffraction theory of wave optics has been developed and applied to quantitatively simulate the in-line diffractive phase-contrast x-ray imaging of three dimensional tissue samples under actual clinic imaging parameters. The primary microcosmic interactions of medical-energy x-ray within matter including photoabsorption, Compton scattering, and coherent scattering, have been taken into account in the Monte Carlo simulation. A diffraction processing based on Fresnel diffraction theory is carried out to simulate the macroscopic diffraction effect. A comparison with experiment results has also been performed.
Spectroscopic ellipsometry study of GaAs1−xBix material grown on GaAs substrate by atmospheric pressure metal-organic vapor-phase epitaxy
Authors: Ben Sedrine Nebiha , Moussa Imed , Fitouri Hedi , Rebey Ahmed , El Jani Belgacem , Chtourou Radhouane
Published: July 2009

The optical properties in terms of complex dielectric function of GaAs1−xBix alloys (0%≤x≤3.7%), grown by atmospheric pressure metal-organic vapor-phase epitaxy, are determined by using room temperature spectroscopic ellipsometry. The interband transition energies in the energy range of 1.4–5.4 eV are resolved using a line shape fitting on the numerically calculated dielectric function second derivatives. The bismuth effect on the critical point parameters is then determined. We have found that, as for GaAs1−xBix alloys E0 transition, the bismuth incorporation shifts the E1, E1+Δ1, E2, and E0′ transition energies but with a lower magnitude. We also observed a root-square-like increase of the E1 broadening parameter (Γ1) with respect to the bismuth composition.
Erratum: “Double layer in an expanding plasma: Simultaneous upstream and downstream measurements” [Phys. Plasmas 15, 102113 (2008)]
Authors: Byhring H. S. , Charles C. , Fredriksen Å. , Boswell R. W.
Published: July 2009

As a result of the discovery of an error in the calibration of the simulated versus the measured magnetic field, a thorough mapping of the axial magnetic field has been carried out. The measurements show that the magnetic field is higher than what was believed to be the case, however, this does not affect the conclusions made in the article.
Competing quantum effects in the dynamics of a flexible water model
Authors: Habershon Scott , Markland Thomas E. , Manolopoulos David E.
Published: July 2009

Numerous studies have identified large quantum mechanical effects in the dynamics of liquid water. In this paper, we suggest that these effects may have been overestimated due to the use of rigid water models and flexible models in which the intramolecular interactions were described using simple harmonic functions. To demonstrate this, we introduce a new simple point charge model for liquid water, q-TIP4P/F, in which the O–H stretches are described by Morse-type functions. We have parametrized this model to give the correct liquid structure, diffusion coefficient, and infrared absorption frequencies in quantum (path integral-based) simulations. The model also reproduces the experimental temperature variation of the liquid density and affords reasonable agreement with the experimental melting temperature of hexagonal ice at atmospheric pressure. By comparing classical and quantum simulations of the liquid, we find that quantum mechanical fluctuations increase the rates of translational diffusion and orientational relaxation in our model by a factor of around 1.15. This effect is much smaller than that observed in all previous simulations of empirical water models, which have found a quantum effect of at least 1.4 regardless of the quantum simulation method or the water model employed. The small quantum effect in our model is a result of two competing phenomena. Intermolecular zero point energy and tunneling effects destabilize the hydrogen-bonding network, leading to a less viscous liquid with a larger diffusion coefficient. However, this is offset by intramolecular zero point motion, which changes the average water monomer geometry resulting in a larger dipole moment, stronger intermolecular interactions, and a slower diffusion. We end by suggesting, on the basis of simulations of other potential energy models, that the small quantum effect we find in the diffusion coefficient is associated with the ability of our model to produce a single broad O–H stretching band in the infrared absorption spectrum.
Improvement in the bias stability of amorphous indium gallium zinc oxide thin-film transistors using an O2 plasma-treated insulator
Authors: Moon Yeon-Keon , Lee Sih , Kim Woong-Sun , Kang Byung-Woo , Jeong Chang-Oh , Lee Dong-Hoon , Park Jong-Wan
Published: July 2009

The effects of an O2 plasma-treated SiNX-based insulator on the interfacial property and the device performances of amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs) were investigated. We tried to improve the interfacial characteristics by reducing the trap density between the SiNX gate insulator and a-IGZO channel by the O2 plasma treatment. The plasma treated-device performances were remarkably improved. The drastic improvements obtained for the O2 plasma-treated a-IGZO TFTs included excellent bias stability as well as a high field effect mobility (μFE) of 19.4 cm2/V s, an on/off current (ION/IOFF) of 108, and a subthreshold value (S) of 0.5 V/decade.
Partial photoionization cross sections of NH4 and H3O Rydberg radicals
Authors: Velasco A. M. , Lavín C. , Martín I. , Melin J. , Ortiz J. V.
Published: July 2009

Photoionization cross sections for various Rydberg series that correspond to ionization channels of ammonium and oxonium Rydberg radicals from the outermost, occupied orbitals of their respective ground states are reported. These properties are known to be relevant in photoelectron dynamics studies. For the present calculations, the molecular-adapted quantum defect orbital method has been employed. A Cooper minimum has been found in the 3sa1-kpt2 Rydberg channel of NH4 beyond the ionization threshold, which provides the main contribution to the photoionization of this radical. However, no net minimum is found in the partial cross section of H3O despite the presence of minima in the 3sa1-kpe and 3sa1-kpa1 Rydberg channels. The complete oscillator strength distributions spanning the discrete and continuous regions of both radicals exhibit the expected continuity across the ionization threshold.
Atomic mechanism of flat-band voltage shifts by La2O3 and Al2O3 in gate stacks
Authors: Lin L. , Robertson J.
Published: July 2009

The origin of the flat-band voltage shifts for La- and Al-based oxide capping layers in high k metal gate stacks is studied by ab initio calculations on atomic models. Substitutional La, Al, Sr, and Nb at the HfO2–SiO2 interface create dipoles, which shift the flat band voltage in the experimentally observed direction, negative for La and Sr and positive for Al and Nb. The shift does not correlate with the metal’s valence, being opposite for La and Al, which rules out a vacancy model. The shift does correlate with the metal electronegativity/work function. It does not correlate with oxygen ion density, as this is not varied.
Lateral metal-semiconductor-metal photodetectors based on amorphous selenium
Authors: Wang Kai , Chen Feng , Belev George , Kasap Safa , Karim Karim S.
Published: July 2009

We report a lateral metal-semiconductor-metal (MSM) photodetector (PD) based on an amorphous selenium (a-Se). The PD exhibits a dark current below 200 fA under electric fields ranging from 6 to 12 V/μm, a responsivity of up to 0.45 A/W, a photogain of 1.2 near short wavelengths of 468 nm, and a high-speed photoresponse with a rise time of 50 μs, fall time of 60 μs, and time constant of 30 μs, respectively. The lateral MSM PD based on a-Se has great potential for use in digital x-ray imaging applications.
Numerical calculations of the irradiation of the cone in a conically guided capsule
Authors: Temporal M. , Ramis R. , Canaud B.
Published: July 2009

A conically guided capsule directly driven by laser beams has been considered. The capsule is irradiated by 31 laser beams characterized by a super-Gaussian power profile. The implosion of the capsule is assumed perfectly spherical, neglecting any effect due to the inserted cone. A three-dimensional ray-tracing package has been developed to evaluate the direct irradiation of the external surface of the inserted cone as a function of time. For the laser-capsule configuration analyzed in this work, it is found that the surface of the cone initially located inside the capsule suffer the highest irradiation with a peak intensity as high as 3×1014 W/cm2.
Acoustic energy harvesting using resonant cavity of a sonic crystal
Authors: Wu Liang-Yu , Chen Lien-Wen , Liu Chia-Ming
Published: July 2009

This paper presents the development of an acoustic energy harvester using the sonic crystal and the piezoelectric material. A point defect is created by removing a rod from a perfect sonic crystal. The point defect in the sonic crystal acts as a resonant cavity, and the acoustic waves at the resonant frequency of the cavity can be localized in the cavity. The power generation from acoustic energy is based on the effect of the wave localization in the cavity of the sonic crystal and the direct piezoelectric effect of the piezoelectric material.
Growth and optical properties of α-sexithiopene doped para-sexiphenyl nanofibers
Authors: Hernandez-Sosa G. , Simbrunner C. , Sitter H.
Published: July 2009

The deposition of highly crystalline self-assembled para-sexiphenyl (PSP) nanofibers doped with α-sexithiophene (6T) is reported. It is demonstrated that the morphology and orientation of the nanofibers are not altered by the presence of 6T, while the photoluminescence (PL) emission can be modified by the doping concentration, suggesting effective incorporation of the dopant into the nanofibers. Moreover, strong dependence of the PL intensity with the excitation polarization underlines the high molecular order within the crystalline matrix. Due to the expected dipole-dipole interaction provided by the highly ordered structures the observed results can be explained by a Förster energy transfer.
Ultrafast switching of a nanomagnet by a combined out-of-plane and in-plane polarized spin current pulse
Authors: Lee O. J. , Pribiag V. S. , Braganca P. M. , Gowtham P. G. , Ralph D. C. , Buhrman R. A.
Published: July 2009

We report on spin valve devices that incorporate both an out-of-plane polarizer (OPP) to quickly excite spin torque (ST) switching and an in-plane polarizer/analyzer (IPP). For pulses <200 ps, we observe reliable precessional switching due largely to ST from the OPP. Compared to a conventional spin valve, for a given current amplitude from ∼2 to 3 times the zero-thermal-fluctuation critical current (Ic0), the addition of the OPP can decrease the pulse width necessary for switching by a factor of 10 or more. The effect of the IPP also has beneficial ST consequences for the short pulse switching behavior.
Ostrich leather quality: a review
Authors: Engelbrecht A. , Hoffman L. C. , Cloete S. W. P. , van Schalkwyk S. J.
Published: July 2009

This review summarises the research that has been published on factors that influence the various aspects of ostrich leather quality, a vital aspect to the economic viability of the commercial ostrich industry. The review is divided into three main sections: discussing intrinsic, pre-slaughter and post-slaughter factors that influence leather quality. Only one literature source that investigated the morphology of ostrich skin could be found. The high vascularity near the surface of the skin was indicated in making the skin susceptible to bruising, which influences skin quality, while the strength and flexibility of ostrich leather was attributed to the three-dimensional cross-weave arrangement of collagen fibres. Various studies reported a high degree of variation in quality within and between ostrich skins. The potential of genetic selection for improved skin quality was also considered, and it was demonstrated that most ostrich leather traits exhibited significant genetic variation. Findings on pre-slaughter factors, such as the effects of age, weight, nutrition and management practices, are also summarised. Few research reports on post-slaughter factors that influence leather quality were found. A few studies looked at the effect of storage on ostrich skin quality, but literature on the effect of processing techniques are lacking. Research priorities identified include the development of methods to assess skin quality on-farm and finding objective methods of evaluating ostrich leather quality.
Frequency distribution of sward height of kikuyu (Pennisetum clandestinum) grass pastures intensively grazed by dairy cows
Authors: Dobos R. C. , Sinclair K. , Hinch G. N. , Fulkerson W. J.
Published: July 2009

Swards that are grazed continuously by cattle can become heterogeneous in structure, such that frequencies of height measurements have a skewed distribution. This structure has been best described by the double-normal, gamma and Weibull distributions rather than by the more common single-normal distribution. Limited analysis of the frequency distribution of sward height under dairy cattle grazing management is available. The current paper reports the frequency distribution of sward height under intensive dairy cow grazing of kikuyu (Pennisetum clandestinum) in a subtropical environment.
Frequencies of sward height were collected during an experiment designed to investigate the effects of compressed sward height and grazing duration on grazing behaviour of dairy cows. There were two compressed sward heights (10 and 13 cm; Earle and McGowan 1979) and five grazing durations (1, 2, 4, 8 and 15 h). The frequency of height measurements taken were then fitted to four distributions – single-normal, log-normal, gamma and Weibull – to determine if treatments influenced the structure of the sward as grazing duration progressed.
The frequency of sward height measurement was best described by the log-normal distribution. However, no one distribution described the frequency of height measurements consistently as grazing duration progressed, as determined by Akaike information criteria. The present analysis did not provide unequivocal evidence for either bimodal or unimodal distributions describing the height measurements for 10- and 13-cm compressed sward height treatments as grazing duration progressed.
Bovine somatotrophin stimulates milk production in red deer hinds
Authors: Barrell G. K. , Archer J. A. , Wellby M. , Ridgway M. J. , Evans M. J.
Published: July 2009

To determine its potential as a tool for studies of growth in suckling red deer calves, bovine somatotrophin (bST) was administered to lactating red deer hinds. The present study used twice-daily machine milking of bST-treated hinds (n = 10, 54 mg bST for 2 weeks then 108 mg for 1 week) and compared the milk yield with that of saline-treated controls (n = 9). Treatment with 54 mg bST tended to increase milk yield by ~16% and the 108-mg dose increased (P = 0.013) milk yield by ~32%. Both doses of bST increased (P < 0.05 and P < 0.001, respectively) plasma insulin-like growth factor-1 concentration but did not affect total solids or fat content of the milk, nor was there any effect on body condition score or liveweight of the hinds. This shows that milk production in red deer hinds is increased by administration of bST, which makes it a suitable experimental technique for investigating the lactational biology of red deer.
Recovery of nanosize zinc from phosphor wastes with an ionic liquid
Authors: Huang Hsin-Liang , Wang H. Paul , Eyring Edward M. , Chang Juu-En
Published: July 2009

Environmental context. Very fine phosphor ashes are discharged from particulate collection systems (such as bag houses) in the cathode ray tube or television disassembling processes. Effective recovery of ZnO and ZnS nanoparticles from the phosphor ash can be achieved by extraction with a room temperature ionic liquid. By synchrotron radiation X-ray absorption spectroscopy, the obtained molecular scale data turn out to be very useful in revealing speciation of zinc in the extraction process, which also facilitates the development of a simple nanoparticle recovery method.
Abstract. An effective, simple method has been developed for the recovery of ZnO and ZnS nanoparticles from hazardous phosphor ash waste. Experimentally, zinc (77%) in the phosphor ash (that contains mainly zinc (91%)) can be recovered by extraction with a room temperature ionic liquid (RTIL) ([C4mim][PF6], 1-butyl-3-methylimidazolium hexafluorophosphate). Component fitted X-ray absorption near edge structure (XANES) spectra of zinc indicate that metallic zinc (Zn) (9%) in the phosphor ash can be dissolved to form a Zn2+–1-methylimidazole ([mim]) complex during extraction with the RTIL. ZnS and ZnO nanoparticles (60–61%) can also be extracted from the phosphor. Over the 298–523 K temperature range, desired ZnO/ZnS ratios (0.3–0.6) can be obtained since interconversion of ZnS to ZnO in the RTIL is temperature dependent. The Fourier transformed extended X-ray absorption fine structure (EXAFS) data also show that the nanosize ZnS extracted in the RTIL possesses a Zn–S bond distance of 2.33 Å with coordination numbers (CNs) of 3.6–3.7. At 523 K, in the RTIL, ~30% of the ZnS is oxidised to form octahedral ZnO (with a bond distance of 2.10 Å and a CN of 6.1) that may coat the surfaces of the ZnS nanoparticles. This work exemplifies the utilisation of X-ray absorption spectroscopy (EXAFS and XANES) to reveal speciation and possible reaction pathways in a nanoparticle extraction process (with a RTIL) in detail.
Relationship between soil composition and retention capacity of terbumeton onto chalky soils
Authors: El Arfaoui Achouak , Sayen Stéphanie , Marceau Eric , Stievano Lorenzo , Guillon Emmanuel , Couderchet Michel
Published: July 2009

Environmental context. The wide use of pesticides for pest and weed control contributes to their presence in underground and surface waters, which has led to a continuously growing interest in their environmental fate. Soils play a key role in the transfer of these compounds from the sprayer to the water as a result of their capacity to retain pesticides depending on the soil components. The knowledge of soil composition should enable one to predict pesticide behaviour in the environment.
Abstract. Eight calcareous soils of Champagne vineyards (France) were studied to investigate the adsorption of the herbicide terbumeton (TER). A preliminary characterisation of the soil samples using X-ray diffraction (XRD), elemental and textural analyses, revealed a wide range of soil properties for the selected samples. The adsorption isotherms of TER were plotted for all samples. The determination of soil properties, which significantly correlated with the Kd distribution coefficient, allowed identification of organic matter and CaCO3 as the two main soil components that govern the retention of the herbicide. Organic matter was the predominant phase involved in the retention but its role was limited by the presence of calcite. Finally, the ratio of CaCO3 content to organic matter content was proposed as a useful parameter to predict the adsorption of terbumeton in chalky soils. The evolution of Kd as a function of this ratio was successfully described using an empirical model.
Arsenic compounds in tropical marine ecosystems: similarities between mangrove forest and coral reef
Authors: Khokiattiwong Somkiat , Kornkanitnan Narumol , Goessler Walter , Kokarnig Sabine , Francesconi Kevin A.
Published: July 2009

Environmental context. Despite the widespread occurrence of arsenobetaine in marine animals the origin of this arsenic compound remains unknown. A current hypothesis is that arsenobetaine is formed from more complex arsenic compounds found in marine algae. To test this hypothesis, we examined the arsenic compounds in a mangrove ecosystem where algae play a limited role in primary productivity.
Abstract. Marine algae are known to bioaccumulate arsenic and transform it into arsenosugars, which are thought to be precursors of the major arsenic compound, arsenobetaine, found in marine animals. Marine ecosystems based on mangrove forests have high nutrient input from mangrove leaves, and thus provide a unique opportunity to study the cycling of arsenic in a marine system where algae are not the dominant food source. Two mangrove forests in Phuket, Thailand were selected as sampling sites for this study. For comparison, samples were also collected from two coral reef sites at and near Phuket. The samples collected included mangrove leaves, corals, algae, molluscs, fish and crustaceans. Arsenic contents in the samples and in aqueous extracts of the samples were determined by hydride generation atomic absorption spectrometry following a dry-ashing mineralisation procedure, and arsenic species were determined in the aqueous extracts by HPLC-MS (mainly ICPMS). Mangrove leaves contained only low concentrations of total arsenic (0.10–0.73 mg kg–1 dry mass) and the aqueous extracts thereof contained inorganic arsenic species, methylarsonate and dimethylarsinate, but arsenosugars were not detected. The total mean arsenic contents (3.2–86 mg kg–1 dry mass) of the animals from the mangrove ecosystem, however, were typical of those found in animal samples from other marine ecosystems. Similarly the arsenic compounds present were typical of those in animals from other marine ecosystems comprising mainly arsenobetaine with smaller quantities of other common arsenicals including arsenosugars, arsenocholine, tetramethylarsonium ion, trimethylarsine oxide and dimethylarsinate. A trimethylated arsenosugar, which is not commonly reported in marine organisms, was a significant arsenical (6–8% of total As) in some gastropod species from the mangrove ecosystem. The coral samples contained mainly arsenosugars and arsenobetaine, and the other animals collected from the coral ecosystem contained essentially the same pattern of arsenicals found for the mangrove animals. The data suggest that food chains based on algae are not necessary for animals to accumulate large concentrations of arsenobetaine.
Predicting availability of mineral elements to plants with the DGT technique: a review of experimental data and interpretation by modelling
Authors: Degryse Fien , Smolders Erik , Zhang Hao , Davison William
Published: July 2009

Environmental context. Total concentrations of mineral elements in soil bear little relation to their availability for plants. The DGT (diffusive gradients in thin-films) technique has been found to be a good predictor of trace metal uptake and P deficiency, though not consistently in all studies for all elements. This review examines the fundamental basis for the relation between DGT fluxes and plant uptake and assesses under which conditions this relation may break down. Abstract. In the DGT technique, elements are accumulated on a binding gel after their diffusive transport through a hydrogel. In this paper, we explore in more detail why – and under which conditions – DGT correlates with plant uptake. The theoretical considerations are illustrated with experimental results for metal uptake and toxicity, and for phosphorus deficiency. Strong correlations between DGT and plant uptake are predicted if the diffusive transport of the element from soil to the plant roots is rate-limiting for its uptake. If uptake is not limited by diffusive transport, DGT-fluxes and plant uptake may still correlate provided that plant uptake is not saturated. However, competitive cations may affect the plant uptake under these conditions, whereas they have no effect on the DGT flux. Moreover, labile complexes are not expected to contribute to the plant uptake if diffusion is not limiting, but they are measured with DGT. Therefore, if plant uptake is not limited by diffusion, interpretation of the observed correlation in terms of the labile species measured by DGT is inappropriate.