bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐frequency identification of non‐volcanic tremor triggered by regional earthquakes
Authors: Guilhem Aurélie , Peng Zhigang , Nadeau Robert M.
Published: August 2010

Subsequent to the discovery of ambient “non‐volcanic” tremor activity along the Parkfield‐Cholame section of the San Andreas fault in central California, triggered tremors associated with the surface waves of large teleseismic earthquakes have been recognized. However, no evidence of triggered tremors from regional earthquakes has previously been found either here or in other tremor regions. By systematically filtering seismograms to higher frequencies (i.e., above 20 Hz) associated with 99 regional M5+ earthquakes since 2001, we identify four regional earthquakes that have triggered tremors in central California. Significant high‐frequency energy is also observed in previously identified teleseismically triggered and ambient tremors, suggesting a common mechanism. We find that long‐period and large‐amplitude surface waves from both regional and teleseismic events have a greater potential of triggering tremor in the same region, and that the inferred minimum triggering dynamic stress is ∼1 kPa.
Air‐lake exchange of methane during the open water season in Syowa Oasis, East Antarctica
Authors: Sasaki Masafumi , Endoh Noboru , Imura Satoshi , Kudoh Sakae , Yamanouchi Takashi , Morimoto Shinji , Hashida Gen
Published: August 2010

Dissolved methane (DM) concentrations were measured in 17 lakes as part of the operations of the 45th Japanese Antarctic Research Expedition in ice‐free rocky areas along the eastern coast of Lützow‐Holm Bay (Syowa Oasis) in East Antarctica in the summer of 2003–2004. DM at the surfaces of 14 lakes ranged from the atmospheric equilibrium concentration (about 4 nmol L−1 for freshwater) to 385 nmol L−1. Relatively low DM of less than 50 nmol L−1 were observed in about 60% of the lakes. Many of the lakes (area fraction of 85%) were supersaturated and are thus sources of methane to the atmosphere. The exchange coefficient was calculated using wind speed data at Syowa Station. Area fraction frequency distributions with four surface DM ranges were applied to all lakes at Syowa Oasis (110 lakes, total lake area of 9 km2). Extrapolation to the whole Syowa Oasis gives an estimate of total emission of about 1 t CH4 yr−1. This is the first estimation of methane flux from the surfaces of thawed lakes to the atmosphere in Antarctica. Since a methane efflux of about 2 t CH4 yr−1 was estimated in our previous study from frozen bubbles in lake ice, a total amount of 3 t CH4 yr−1 would be released to the atmosphere from the lakes during the ice melting season (December–January) at Syowa Oasis.
The Bidirectional Relations between Affect and Belief
Authors: Boden Matthew Tyler , Berenbaum Howard
Published: August 2010

Whereas a majority of previous work has focused on the cognitive factors that influence beliefs, current theory and research suggest that affect also plays an important role. In this article, we comprehensively describe the bidirectional relations between affect and belief. On the basis of our review of existing theory and research, we develop the following three empirically derived premises. First, the need to make sense of experience and the need to regulate affect drive a reciprocal feedback loop through which affect and belief influence each other. Second, changes in affect arousal, valence, and type influence belief content and conviction. Third, changes in belief content and conviction influence affect arousal, valence, and type. We discuss empirical research supporting each premise, needed empirical tests, and avenues for future research.
Using Creativity to Reduce Ethnic Bias in College Admissions
Authors: Kaufman James C.
Published: August 2010

College admissions testing typically focuses on grade point average (GPA) and SAT scores. Without disputing the importance of these predictors, one may wonder whether they are enough by themselves to determine eventual academic success. One possible additional construct, creativity, is examined via the lens of nonbiased assessment. It is argued that creativity can help reduce bias in two ways. First, adding creativity as a supplement to current assessments would present a truer reflection of a person's overall intellectual abilities. Second, most studies have found that different ethnicities perform comparably on creativity tasks, and some minority groups may be more likely to see themselves as creative. Including creativity as a component of standardized tests may, therefore, reduce stereotype threat.
Systemic and cardiac hemodynamic interactions between clonidine and minoxidil
Authors: Velasco Manuel , Andrews‐Figueroa Pedro , Ramiŕez Ana , Morillo Julio , Urbina‐Quintana Adalberto , Alienares Ricardo , Hernańdez‐Pieretti Otto
Published: August 2010

We examined the hemodynamic interaction between clonidine, a centrally acting antiadrenergic drug, and minoxidil, a potent antihypertensive vasodilator in 10 inpatients with refractory or accelerated hypertension or both. Clonidine in oral doses of 150 to 900 μg/day decreased average mean blood pressure 18.6 mm Hg (p < 0.01), average heart rate 16.4 bpm (p < 0.01), limb blood flow 1.63 ml/100 gm · min (p < 0.05), and plasma renin activity 1.13 ng/ml · hr (p < 0.025). It also increased the pre‐ejection period index 12.4 msec (p < 0.001), but did not alter the cardiac or total peripheral resistance indices. The addition of minoxidil in oral doses of 5 to 22.5 mg/day further decreased average mean blood pressure 24.2 mm Hg (p < 0.01), preejection period index 20.6 msec (p < 0.01), limb vascular resistance 13.2 mm Hg/min · 100 gm/ml (p < 0.05), and total peripheral resistance 13.3 mm Hg/min · m2/l (p < 0.01), pre‐ejection period index 20.6 msec (p < 0.01), limb vascular resistance 13.2 mm Hg/min · 100 gm/ml (p < 0.05), and total peripheral resistance 13.3 mm Hg/min · m2/l concluded that clonidine can be used as an alternative to β‐adrenergic blockers to counteract the increased sympathetic nervous activity minoxidil induces.

Clinical Pharmacology and Therapeutics (1981) 30, 158–163; doi:10.1038/clpt.1981.142
Helicobacter pylori HtrA is a new secreted virulence factor that cleaves E‐cadherin to disrupt intercellular adhesion
Authors: Hoy Benjamin , Löwer Martin , Weydig Christiane , Carra Gert , Tegtmeyer Nicole , Geppert Tim , Schröder Peter , Sewald Norbert , Backert Steffen , Schneider Gisbert , Wessler Silja
Published: September 2010

Mammalian and prokaryotic high‐temperature requirement A (HtrA) proteins are chaperones and serine proteases with important roles in protein quality control. Here, we describe an entirely new function of HtrA and identify it as a new secreted virulence factor from Helicobacter pylori, which cleaves the ectodomain of the cell‐adhesion protein E‐cadherin. E‐cadherin shedding disrupts epithelial barrier functions allowing H. pylori designed to access the intercellular space. We then designed a small‐molecule inhibitor that efficiently blocks HtrA activity, E‐cadherin cleavage and intercellular entry of H. pylori.
Two-dimensional quasicontinuum analysis of the strengthening and weakening effect of Cu/Ag interface on nanoindentation
Authors: Li Junwan , Mei Jifa , Ni Yushan , Lu Huaibao , Jiang Wugui
Published: September 2010

Multiscale simulations using the two-dimensional quasicontinuum method are performed to understand the nature of strengthening and weakening effect of Cu/Ag interface on nanoindentation at zero temperature. The investigation shows that the upper Cu film strengthens distinctly the lower Ag substrate. The nucleation and emission for first dislocation in Cu film is postponed obviously due to the effect of interface. Combined with the dislocation theory, a dislocation model of the interaction between the nucleated dislocation and the misfit dislocation is introduced to systematically evaluate the strengthening and weakening effects of interface on the Cu/Ag bilayer film system. It is found that the strengthening effect of interface on nanoindentation is governed by the resistance to the nucleated dislocation transmission, such as image force, lattice friction, and the repulsive force of the misfit dislocation. The bigger resistance will lead to the stronger strengthening effect. The weakening effect is mainly produced by the stress concentration and local misfit strain in the core region of the misfit dislocations due to the nucleation and propagation of misfit dislocations along the interface. The multiscale simulation results are in good agreement with the experimental results and dislocation theory model.
Angular momentum dynamics and the intrinsic drift of monopolar vortices on a rotating sphere
Authors: van der Toorn Ramses , Zimmerman Joseph T. F.
Published: August 2010

On the basis of the angular momentum equation for a fluid shell on a rotating planet, we analyze the intrinsic drift of a monopolar vortex in the shell. Central is the development of a general angular momentum equation for Eulerian fluid mechanics based on coordinate-free, general tensorial representations of the underlying fluid dynamics on the one hand, and an appropriate representation of the Lie algebra so(3) of rotations on the other hand. We show that angular momentum fluid dynamics concisely describes the motion of vortices along the sphere and explains why both geostrophic cyclones and anticyclones drift in retrograde direction (westward), why anticyclones do so faster than cyclones, and why this difference is enhanced by a cyclostrophic correction. Technically, the analysis is based on a tensorial representation of the integral angular momentum equation for the fluid shell as a whole, and, derived from this, a coordinate representation with respect to coordinates which may move with the vortex along the surface of the planet. Depicting the angular momentum balance of cyclones and anticyclones in terms of vector diagrams, we present an overview of the results achieved.
Introducing dipole-like resonance into magnetic resonance to realize simultaneous drop in transmission and reflection at terahertz frequency
Authors: Hu ChengGang , Li Xiong , Feng Qin , Chen Xu’Nan , Luo XianGang
Published: September 2010

A metamaterial (MM) consisting of double layer closed rings (DCRs) and a split-wire shows the different manipulations of the transmission T(ω) and reflection R(ω) to obtain simultaneous minimums. Parametric studies on the MM and a further LC circuit model are proposed, showing that the phenomenon is dominated by the interaction of the additional dipole-like resonance supported by the split-wire and the primary magnetic resonance supported by DCRs. Simultaneous sharp drops in T(ω) and R(ω) are observed in our MM at about 2.45 THz. The potential applications for near-perfect absorption and dual-directional absorption are discussed.
Molecular simulations of structures and solvation free energies of passivated gold nanoparticles in supercritical CO2
Authors: Yang Zhen , Yang Xiaoning , Xu Zhijun , Yang Nannan
Published: September 2010

The interfacial structures and solvation free energies of gold nanoparticles passivated by self-assembled monolayer (SAM) of fluorinated alkanethiols in supercritical CO2 (scCO2) have been studied by using classical molecular dynamics simulation. A fragment-based free-energy perturbation approach was developed here, in which the solvation free energy of passivated metal nanoparticles was partitioned into the contributions from the inner metal core and the outer SAM. This is a first-time attempt to directly simulate the solvation free energy of nano-objects in supercritical fluids. The simulation result suggests that the nanoparticles can be thermodynamically soluble at lower scCO2 density but insoluble at higher density. We have demonstrated that this density dependence of solvation free energy can be ascribed to the effect of the surface SAM in scCO2. The presence of solvent molecules greatly affects the morphology of SAM on nanoparticle. It was observed that increasing the chain length in SAM makes nanoparticles more solvophilic at lower scCO2 density or more solvophobic at higher density. This solvation thermodynamics behavior has been correlated with the specific solvation structure of scCO2 around the passivated nanoparticles.
Thermal wave induced edge electrical field of pyroelectric: Spatial pattern mapping and effect of ambient conditions
Authors: Butenko A. V. , Sandomirsky V. , Chaniel G. , Shapiro B. , Schlesinger Y. , Jarov A. , Sablikov V. A.
Published: August 2010

We have recently analyzed theoretically the main characteristics of the edge depolarizing electric field (EDEF), in the vicinity of a nonpolar face of a pyroelectric. In this work, we measured and characterized the EDEF, excited by a harmonical thermal wave. We present here experimental results obtained on a pyroelectric crystal LiTaO3, confirming our theoretical predictions. The interpretation assumes an equivalent circuit of a pyroelectric capacitive current source. The effect of the air pressure at the pyroelectric/air interface, on the EDEF, was determined in the interval 103–10−5 torr. We found that EDEF increases significantly with decreasing air pressure, presumably due to diminishing of adsorption screening at the polar faces. Teflon plates, covering the polar faces, prevent accumulation of screening charged particles, resulting in a significant increase in EDEF. Our experimental results highlight the feasibility of EDEF application in micro- and nanotechnology as a contactless controlled electrical field.
Microscopic second-harmonic generation emission direction in fibrillous collagen type I by quasi-phase-matching theory
Authors: Tian Long , Qu Junle , Guo Zhouyi , Jin Ying , Meng Yaoyong , Deng Xiaoyuan
Published: September 2010

Quasiphase matching (QPM) is a widely used theory in crystal to analyze the character of second-harmonic generation (SHG) emitted from it. Based on the structural features of collagen type I, where the constituted fibrils in collagen function as a crystal which has the structure of two-dimensional (2D) quasicrystalline, in this paper, we use the QPM theory on collagen for SHG emission direction study under the excitation of laser light through a microscope. The effects of numerical aperture NA, as well as the structural parameters, such as QPM order (m,l) and collagen period a=d1+d2 associated with the fibrils diameter (d1), packing density and interfibrils structure (d2), etc., on SHG emission angle φ have been investigated. Our theoretical results show that collagen period a has threshold effect on φ to present forward or backward SHG emission and NA has minor influence on this threshold value a. Collagen period of a has more significant influence on SHG emission angle φ when a is smaller than the threshold value. In reality, we realize that diameter of collagen fibrils d1 plays a major role on forward or backward emission of SHG. Here, for example, (we assume d1=a/2), when d1≤95 nm [(m,l)=(1,0)], the backward SHG shows up at any magnitude of NA, while when d1≥150 nm [(m,l)=(1,0)], SHG presents forward emission feature under all circumstances. Between them, SHG emits from forward direction to backward direction as the increase in NA. The QPM order (m,l) has nonlinear impact on SHG emission angle φ and has different degrees of influence on different collagen period a. Our theoretical results are highly consistent with the experiments results demonstrated by other researchers and provide a proper explanation of the phenomenon of appreciable backward SHG signals appearing in collagen type I. Our established theoretical model of applying QPM theory in 2D quasicrystalline fibrils is therefore confirmed to be a suitable model for dealing with SHG in type I collagen.
Attenuation of single-tone ultrasound by an atmospheric glow discharge plasma barrier
Authors: Stepaniuk Vadim P. , Ioppolo Tindaro , Ötügen M. Volkan , Sheverev Valery A.
Published: September 2010

Propagation of 143 kHz ultrasound through an atmospheric pressure glow discharge in air was studied experimentally. The plasma was a continuous dc discharge formed by a multipin electrode system. Distributions of the gas temperature were also obtained in and around the plasma using laser-induced Rayleigh scattering technique. Results show significant attenuation of the ultrasound by the glow discharge plasma barrier (up to −24 dB). The results indicate that sound attenuation does not depend on the thickness of the plasma and attenuation is caused primarily by reflection of the sound waves from the plasma due to the sharp gas temperatures gradients that form at the plasma boundary. These gradients can be as high as 80 K/mm.
A first principles based polarizable O(N) interatomic force field for bulk silica
Authors: Kermode J. R. , Cereda S. , Tangney P. , De Vita A.
Published: September 2010

We present a reformulation of the Tangney–Scandolo interatomic force field for silica [J. Chem. Phys. 117, 8898 (2002)], which removes the requirement to perform an Ewald summation. We use a Yukawa factor to screen electrostatic interactions and a cutoff distance to limit the interatomic potential range to around 10 Å. A reparametrization of the potential is carried out, fitting to data from density functional theory calculations. These calculations were performed within the local density approximation since we find that this choice of functional leads to a better match to the experimental structural and elastic properties of quartz and amorphous silica than the generalized gradient approximation approach used to parametrize the original Tangney–Scandolo force field. The resulting O(N) scheme makes it possible to model hundreds of thousands of atoms with modest computational resources, without compromising the force field accuracy. The new potential is validated by calculating structural, elastic, vibrational, and thermodynamic properties of α-quartz and amorphous silica.
Role of phonons in the optical properties of magnetron sputtered ZnO studied by resonance Raman and photoluminescence
Authors: Sohal Sandeep , Alivov Yahya , Fan Zhaoyang , Holtz Mark
Published: September 2010

The temperature dependence of phonons in ZnO has been studied using resonance Raman and photoluminescence (PL) emission measurements. Excitation with wavelength 363.8 nm (photon energy 3.409 eV) is used to establish incoming resonance near room temperature. Broad PL emission is seen at room temperature with peak position at 3.25 eV. This coincides with the overtone of the longitudinal optic (LO) band. Up to six LO phonon orders are observed. Temperature dependence of the LO phonon energy is described by a two-phonon decay mechanism with energies 100 and 496 cm−1. The temperature dependence of the PL shift is interpreted based on electron-phonon interactions. A two-phonon description is sufficient to describe the temperature shift in the band gap through occupation at average acoustic and optic phonon energies 125 and 500 cm−1, respectively. LO phonon sidebands (PSBs) are also observed at low temperature (23 to 100 K). The temperature shift in the PSB energies is interpreted based on the band gap shift combined with established theory for the PSBs.
Electron spin resonance of Zn1−xMgxO thin films grown by plasma-assisted molecular beam epitaxy
Authors: Wassner T. A. , Laumer B. , Althammer M. , Goennenwein S. T. B. , Stutzmann M. , Eickhoff M. , Brandt M. S.
Published: August 2010

Zn 1 − x Mg x O thin films with a Mg content x between 0 and 0.42 grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates were investigated by electron spin resonance at 5 K. Above band gap illumination induces a persistent resonance signal, which is attributed to free conduction band electrons. The g-factors of the Zn1−xMgxO epitaxial layers and their anisotropy were determined experimentally and an increase from g∥=1.957 for x=0 to g∥=1.970 for x=0.42 was found, accompanied by a decrease in anisotropy. A comparison with g-factors of the AlxGa1−xN system is also given.
Magnetostructural relations from a combined ab initio and ligand field analysis for the nonintuitive zero-field splitting in Mn(III) complexes
Authors: Maurice Rémi , de Graaf Coen , Guihéry Nathalie
Published: August 2010

The zero-field splitting (ZFS) of a model monometallic Mn(III) complex is theoretically studied as function of a systematic symmetry lowering. First, we treat the octahedral case for which the standard Ŝ⋅D̿⋅Ŝ model Hamiltonian cannot be applied due to a zero-field splitting in the absence of anisotropy induced by the spin-orbit coupling between the two spatial components of the E5g state at second-order of perturbation. Next, the symmetry is lowered to D4h and D2h and the anisotropic spin Hamiltonian is extracted using effective Hamiltonian theory. A simple relation is derived between the ratio E/|D| and the applied rhombic and axial distortions. Moreover, it is shown that close to Oh symmetry, the orbital mixing due to spin-orbit coupling can be accurately described with Stevens fourth-order operators. The calculated tendencies are interpreted within a refined Racah plus ligand field model and it is shown that the ZFS parameters in Mn(III) complexes follow special rules that are nonintuitive compared to other dn configurations. Finally, some angular distortions are applied to study their effect on the anisotropy.
Invited Review Article: IceCube: An instrument for neutrino astronomy
Authors: Halzen Francis , Klein Spencer R.
Published: August 2010

Neutrino astronomy beyond the Sun was first imagined in the late 1950s; by the 1970s, it was realized that kilometer-scale neutrino detectors were required. The first such instrument, IceCube, is near completion and taking data. The IceCube project transforms 1 km3 of deep and ultratransparent Antarctic ice into a particle detector. A total of 5160 optical sensors is embedded into a gigaton of Antarctic ice to detect the Cherenkov light emitted by secondary particles produced when neutrinos interact with nuclei in the ice. Each optical sensor is a complete data acquisition system including a phototube, digitization electronics, control and trigger systems, and light-emitting diodes for calibration. The light patterns reveal the type (flavor) of neutrino interaction and the energy and direction of the neutrino, making neutrino astronomy possible. The scientific missions of IceCube include such varied tasks as the search for sources of cosmic rays, the observation of galactic supernova explosions, the search for dark matter, and the study of the neutrinos themselves. These reach energies well beyond those produced with accelerator beams. The outline of this review is as follows: neutrino astronomy and kilometer-scale detectors, high-energy neutrino telescopes: methodologies of neutrino detection, IceCube hardware, high-energy neutrino telescopes: beyond astronomy, and future projects.
Bimodel onset strain relaxation in InAs quantum dots with an InGaAs capping layer
Authors: Chen J. F. , Chen Ross C. C. , Chiang C. H. , Chen Y. F. , Wu Y. H. , Chang L.
Published: September 2010

Capping InAs quantum dots (QDs) with an InGaAs layer allows strain relaxation to induce a low-energy electron state below a set of fine dot family states, which is consistent with photoluminescence (PL) spectra. The evolution of InAs thickness suggests a bimodal onset relaxation, i.e., a fine dot family that is strain-relieved by indium outdiffusion from the QDs, as suggested by transmission electron microscopy, and a low-energy dot family that is strain relaxed by the generation of lattice misfits. The indium outdiffusion can explain an abnormal PL blueshift in 70 meV in the fine dot family at onset of strain relaxation.
Low-frequency noise in diamond solution-gated field effect transistors
Authors: Hauf M. V. , Hess L. H. , Howgate J. , Dankerl M. , Stutzmann M. , Garrido J. A.
Published: September 2010

Electronic noise is investigated in diamond solution-gated field effect transistors. They exhibit 1/f-type noise, which is evaluated according to Hooge’s empirical relation. Correcting for the contribution of access regions, the Hooge parameter is found to be inversely proportional to the carrier density, suggesting that the noise originates from fluctuations in the number of charge carriers. Trapping and detrapping of charge carriers at dislocations of the diamond crystal is considered the main source of noise. An effective gate voltage noise of 16 μV rms is observed, which is comparable to the noise of similar devices based on Si and GaN.
Epitaxial growth and magnetic properties of Fe3O4 films on TiN buffered Si(001), Si(110), and Si(111) substrates
Authors: Xiang Hua , Shi Fengyuan , Rzchowski Mark S. , Voyles Paul M. , Chang Y. Austin
Published: September 2010

Epitaxial Fe3O4 thin films were grown on TiN buffered Si(001), Si(110), and Si(111) substrates by dc reactive sputtering deposition. Both Fe3O4 films and TiN buffer are fully epitaxial when grown at substrate temperatures above 150 °C, with textured single phase Fe3O4 resulting from room temperature growth. The initial sputtered Fe3O4 formed nuclei islands and then coalesced to epitaxial columnar grains with increasing film thickness. The magnetization decreases and the coercive field increases with decreasing film thickness. There is no in-plane magnetic anisotropy of epitaxial Fe3O4(001) on Si(001) but Fe3O4 films grown on Si(110) and Si(111) substrates show uniaxial in-plane magnetic anisotropy.
Surface plasmon enhanced responsivity in a waveguided germanium metal-semiconductor-metal photodetector
Authors: Ren Fang-Fang , Ang Kah-Wee , Song Junfeng , Fang Qing , Yu Mingbin , Lo Guo-Qiang , Kwong Dim-Lee
Published: August 2010

The authors report on high transverse magnetic (TM)-mode responsivity in a waveguided germanium Schottky-barrier metal-semiconductor-metal photodetector on silicon-on-insulator substrate for operating wavelength at 1550 nm. The employed aluminum interdigitated electrodes act as a one-dimensional rectangular grating above the depletion layer. By means of properly designed finger dimensions, surface plasmon polariton resonances can be excited at the interface of metal and silicon interfacial layer due to grating coupling. The resulting strong field intensities reach into active region, enabling high absorption under TM injection. At a voltage of 1 V, the TM-mode photocurrent is measured over three times than that of transverse electric mode, in spite of the relatively larger TM insertion loss in the silicon waveguide.
Spin-lattice coupling and helical-spin driven ferroelectric polarization in multiferroic CuFeO2
Authors: Zhong Chonggui , Cao Haixia , Fang Jinghuai , Jiang Xuefan , Ji Xianming , Dong Zhengchao
Published: September 2010

Based on density functional theory, we elucidate the origin of ferroelectricity of multiferroic CuFeO2 with collinear and noncollinear magnetic structure calculations. By comparing the lattice geometry and electronic structures of different magnetic orderings, we confirm that the up-up-down-down spin arrangement plays an important role in the formation of band gap, the decrease in total energy, and the increase in magnetic moment. However, the system of CuFeO2 undergoes a large lattice distortion due to helical-spin ordering. In particular, the strong hybridizations of Fe 3d with O 2p states drive ferroelectric polarization, which provides a first-principle understanding of multiferroicity in CuFeO2.
Conductivity of a graphene strip: Width and gate-voltage dependencies
Authors: Vasko F. T. , Zozoulenko I. V.
Published: September 2010

We study the conductivity of a graphene strip taking into account electrostatically induced charge accumulation on its edges. Using a local dependency of the conductivity on the carrier concentration we find that the electrostatic size effect in doped graphene strip of the width of 0.5–3 μm can result in a significant (about 40%) enhancement of the effective conductivity in comparison to the infinitely wide samples. This effect should be taken into account both in the device simulation as well as for verification of scattering mechanisms in graphene.
Reduction in high reset currents in unipolar resistance switching Pt/SrTiOx/Pt capacitors using acceptor doping
Authors: Lee S. B. , Kim A. , Lee J. S. , Chang S. H. , Yoo H. K. , Noh T. W. , Kahng B. , Lee M.-J. , Kim C. J. , Kang B. S.
Published: September 2010

The high reset current, IR, in unipolar resistance switching is an important issue which should be resolved for practical applications in nonvolatile memories. We showed that, during the forming and set processes, the compliance current, Icomp, can work as a crucial parameter to reduce IR. Doping with Co or Mn can significantly reduce the leakage current in capacitors made using SrTiOx film, opening a larger operation window for Icomp. By decreasing Icomp with acceptor doping, we could reduce IR in SrTiOx films by a factor of approximately 20. Our work suggests that the decrease in Icomp by carrier doping could be a viable alternative for reducing IR in unipolar resistance switching.
Substrate-induced bianisotropy in metamaterials
Authors: Powell David A. , Kivshar Yuri S.
Published: September 2010

We demonstrate that the presence of a supporting substrate can break the symmetry of a metamaterial structure, changing the symmetry of its effective parameters, and giving rise to bianisotropy. This indicates that magnetoelectric coupling will occur in all metamaterials fabricated on a substrate, including those with symmetric designs.
Effects of dietary nitrate on fermentation, methane production and digesta kinetics in sheep
Authors: Nolan J. V. , Hegarty R. S. , Hegarty J. , Godwin I. R. , Woodgate R.
Published: August 2010

The effects of dietary nitrate on DM digestion, rumen volatile fatty acid concentrations, microbial protein outflow, rumen water kinetics, and methane production were studied. Eight rumen-cannulated sheep were acclimated to a diet consisting of chaffed oaten hay supplemented with either 4% KNO3 or 0% KNO3 but made iso-nitrogenous by the addition of urea. Nitrate supplementation did not affect blood methaemoglobin concentration, DM intake, whole tract or ruminal DM digestibility and the sheep appeared healthy at all times throughout the acclimation and experimental periods. Nitrate did cause changes in rumen fermentation consistent with its acting as a high-affinity hydrogen acceptor, i.e. there was a tendency towards a lower molar percentage of propionate in the rumen volatile fatty acids, and higher molar ratio of acetate to propionate. Methane yield (MY, L methane/kg DM intake) was reduced by 23% in KNO3-supplemented sheep (P < 0.05) and these sheep tended to have a shorter mean fluid retention time in the rumen (MRT). There was a significant association between MRT and MY, such that a shorter MRT was associated with a lower MY. The results confirmed that the presence of nitrate in the diet lowers enteric methane production even though there was considerable between-animal variation in gut kinetics and methane production.
Effect of breeding for milk yield, diet and management on enteric methane emissions from dairy cows
Authors: Bell M. J. , Wall E. , Russell G. , Morgan C. , Simm G.
Published: August 2010

Enteric methane production from livestock is an important source of anthropogenic greenhouse gas emissions. The aim of the present study was to (1) assess the effect of long-term breeding for kilograms of milk fat plus protein production and (2) investigate the influence of parity, genetic line and diet on predicted enteric methane emissions of Holstein Friesian dairy cows. Analyses were based on 17 years of experimental data for lactating and dry cows, housed and at pasture. Restricted maximum likelihood (REML) was used to assess the effects of parity, genetic line and diet on the predicted enteric methane output of lactating and dry cows. A non-linear equation based on metabolisable energy intake (MEI) was used to predict daily enteric methane output. The present study found that selection for kilograms of milk fat plus protein production, zero-grazing low-forage diets and maintaining persistently high-yielding older cows can reduce a cow’s enteric methane emissions per kilogram milk by up to 12%, on average. Comparing the first 5 years to the most recent 5 years of the study period showed that large savings of 19% and 23% in enteric methane per kilogram milk were made in cows selected for milk fat plus protein or selected to remain close to the average genetic merit for milk fat plus protein production for all animals evaluated in the UK, respectively. Additionally, management to minimise the length of the drying-off period can help reduce enteric methane emissions during a cow’s lactation period.
Anthracyclines. XIII The Synthesis of (+)-(4R,6R)- and (+)-(4S,6R)-6-Acetyl-6-(t-butyldimethylsilyloxy)-4-ethoxy-4-methoxy-5,6,7,8-tetrahydronaphthalen-1(4H)-one: New Chiral AB Synthons for the Synthesis of (—)-7-Deoxydaunomycinone
Authors: Russell RA , Irvine RW , Warrener RN
Published: September 2010

The title dienones have been prepared from (-)-(2R,1′S)-8-benzyloxy-2-(1′-hydroxyethyl)-5-methoxy-1,2,3,4-tetrahydronaphthalen-2-ol, by a series of reactions in which the selective cleavage of an aryl methyl ether in the presence of an aryl ethyl ether plays a key role. This 10- step sequence proceeds in an overall yield of 55%, and chiral integrity is preserved throughout.
Interfacial Charge Separartion in the Photoreduction of Water: Effects of Colloidal Silica
Authors: Furlong DN , Johansen O , Launikonis A , Loder JW , Mau AWH , Sasse WHF
Published: September 2010

It has been confirmed that colloidal silica can retard reverse electron transfer in the photochemical system water/ tris (2,2′- bipyridine )ruthenium dication/triethanolamine/zwitterionic viologen . However, the beneficial effect of silica diminishes as the concentration of the electron donor ( triethanolamine ) increases. Substantially higher yields of hydrogen
have been obtained with 2,2′,6,6′-tetramethyl-1,1′- di (3-sulfonatopropyl)-4,4′-bipyridinediium which is more stable and has a more favourable potential than previously used electron-transfer agents.
Structural Characterization of a [Cl3CuL]- (L=Nitrogen Base) Species. A Novel Coordination Environment for Copper(II)
Authors: Healy PC , Pakawatchai C , White AH
Published: September 2010

The crystal structure of [C13H10N] [CuCl3(C13H9N)].H2O(C13H9N
≡ acridine ) has been determined by single-crystal X-ray diffraction methods at 295 K, being refined by least squares to a residual of 0.037 for 1942 independent 'observed' reflections. Crystals are triclinic, Pī , a 16.27(2), b 10.080(8), c 7.236(5) Ǻ, α 88.85(6), β 82.68(8), γ 81.12(9)°, Z 2. The metal atom stereochemistry is unusual, being of pseudo-m symmetry; one of the chlorine atoms is coplanar with the copper and the acridine [Cu- Cl 2.237(2) Ǻ,
N-Cu- Cl 143.5(1)°], with the other two disposed to either side of that plane [Cu- Cl 2.252(3), 2.243(2) Ǻ; Cl-Cu-Cl 145.62(7)°]. Cu-N is 2.018(5) Ǻ.
Concerning the Problem of the Isokinetic Relationship. III. The Temperature-Dependance of the hammett Equation
Authors: Linert W , Schmid R , Kudrjawtsev AB
Published: September 2010

It is shown that the temperature-dependence of the Hammett equation is, in contrast to tradition, both physically and experimentally better described by means of temperature-dependent σ and temperature- independent ρ (termed ρo). The relationship between ρo and the customary (temperature dependent) ρ is ρT = ρo(1/T-1/Tbiso)/(1/T-1/Tbiso) where Tbiso , is the isoequilibrium temperature of the benzoic acid ionization, for which the present analysis suggests a value of -255 K, and T is 298 K. In these terms, the temperature variation of the Hammett equation can be evaluated by supplying merely E(u)a (the activation energy for the reaction of the unsubstituted reactant) and ρo, in that the σ value for the isokinetic substituent , i.e., the
abscissa of the common point of intersection in the Hammett plot, is σiso = (1/T-1/Tbiso)E(u)a/(2.303Rρo) = E(u)a/(2630po) Further, ρo I
related to energies ρo = E(u)a/(ΔH°u-ΔH°s(iso))where ΔH°u and ΔH°s(iso) are the ionization enthalpies of the parent benzoic acid and that bearing the isokinetic substituent , respectively. Analogous equations apply to thermodynamic reaction series when substituting E(u)a for ΔH°u(series). Along these lines the interpretation of the customary Hammett plot is advanced.
Copper, Thioamide Complexes. Syntheses and Structures of Di-m-chloro-bis[N-(pyridin-2-yl)benzenecarbothioamide-S,N']dicopper(I) and of Bis[N-(pyridin-2-yl)benzenecarbothioamide-S,N']copper(I) Chloride, Complxes Containing Tetrahedrally Coordinated Copper Centres
Authors: Fuller MW , Costanzo V , Murray KS , Black DSC , Hambly TW , Snow MR
Published: September 2010

The mononuclear copper(I)
complex Cu(PhCSNHC5H4N)2Cl (Cu( pbctaH )2Cl) and the binuclear copper(I) complex [Cu(PhCSNHC5H4N) Cl ]2 ([Cu( pbctaH ) Cl ]2) have been prepared from copper(II) chloride and N-(pyridin-2- yl ) benzenecarbothioamide ( pbctaH ) and their structures detertnined by single-crystal X-ray diffraction studies. Cu(PhCSNHC5H4)2Cl
crystallizes in the space group C2/c with the parameters a 28.042(3) Ǻ, b 6.385(a) Ǻ, c 14.158(12) Ǻ, β 117.01(1)°. The stereochemistry about the copper is essentially tetrahedral, with coordination occurring through the pyridine nitrogen and the sulfur of the thioamide group, and an NCuS angle of 95.7(1)°. [Cu(PhCSNHC5H4N)2Cl]2 crystallizes in the space group C2/c with the parameters a 16.538(6) Ǻ, b
9.135(4) Ǻ, c 16.470(6) Ǻ, β 93.925(15)°. The crystal is made up of binuclear chloro -bridged units, the essentially tetrahedral stereochemistry about the copper atoms being completed by coordination from the pyridine nitrogen and the sulfur of the thioamide group, with an NCuS angle of 99.5(1)°. The Cu2Cl2 group is non-planar, with the copper atoms 0.133 Ǻ above and the chlorine atoms 0.133 Ǻ below the average plane. Other complexes can be isolated from reactions of excess copper(II) chloride with ligand although their structures have not been characterized. A diamagnetic orange compound and a paramagnetic yellow compound apparently derived from copper(n) oxidation of the thioamide were also obtained. Other products, prepared under more basic conditions, are also described. No stable copper(II) complexes of the parent thioamide could be isolated. Use of a 4-nitro substituted benzenecarbothioamide ligand did, however, produce a bis-chelated copper(II) complex.
The Chemistry of Phthalide-3-carboxylic Acid. II. Decarboxylation of Salts in the Presence of Aldehydes
Authors: Dibbens JA , Prager RH , Schiesser CH , Wells AJ
Published: September 2010

Salts of phthalide-3-carboxylic acid decarboxylate in the presence of aromatic aldehydes to give mixtures of the 3-( arylhydroxymethyl ) phthalide (2) and the 2-aryl-3-hydroxyindenone (3). The former may be obtained exclusively in the presence of the weak proton donor, triethyl (2-phenylethyl)ammonium chloride, and the latter in the presence of crown ethers or after longer reaction times. A study of the effect of different cations allows a mechanism to be deduced.
The Chemistry of Phthalide-3-carboxylic Acid. III. Decarboxylation of Salts in the Presence of α,Β-Unsaturated Ketones
Authors: Janowski WK , Prager RH
Published: September 2010

Potassium phthalide-3-carboxylate (3-oxo-1,3-dihydroisobenzofuran-1- carboxylate ) decarboxylates readily in dimethyl sulfoxide at 145°, and the intermediate phthalidyl anion is efficiently trapped by α,β - unsaturated ketones. The major 1,4-addition product is accompanied by smaller amounts of an isomeric product formed by subsequent cyclization and rearrangement, and sometimes traces of a 1 : 2 1,4-addition product. The caesium salt gives slightly more cyclized product, and the lithium salt undergoes very slow decarboxylation. The synthetic usefulness of the salt decarboxylation is compared with that of the free acid.
Free-Radical Reductions of Arenediazonium Ions in Aqueous Solution. VI. On Iododediazoniation
Authors: Packer JE , Taylor RER
Published: September 2010

γ-Irradiation of aqueous solutions of p-ClC6H4N2+BF4- and KI initiates a chain reaction in which dichloroazobenzene is the major product. When iodine is also present the chain reaction is longer and the major product is chloroiodobenzene . The reaction � ������������������������� I2-·+ArN2+
→ I2+Ar·+N2 is suggested to be propagation step in both reactions, with Ar · reacting with I3- in the presence of iodine and with ArN2+ in its absence. The relevance of these reactions to iododediazoniation is discussed.
The Synthesis and Photochemistry of p-Dimethylamino-p′-nitrodiphenylethyne: a Push-Pull Acetylene
Authors: Gallagher MJ , Gallagher MJ , Noerdin H , Noerdin H
Published: September 2010

The title compound (2) was prepared as a possible precursor to a push- pull cyclobutadiene, and its photochemistry examined under a wide range of conditions. The principal reaction observed was loss of a methyl group, and no evidence for bimolecular reactions was observed. The alkyne (2) readily added water, acetic acid and HCl to give the expected products, but failed to react with Fe2(CO)9. 1H and 13C n.m.r , data are reported.
Unfused Heterobicycles as Amplifiers of Phleomycin. VII> Some Bithiazoles; Thienyl-, Furanyl- and Thiazolyl-thiadiazoles and Related Oxadiazoles
Authors: Cowden WB , Sullivan SJ , Brown DJ
Published: September 2010

Syntheses are described for several unfused heterobicycles including 4,5′- and 2,4′-bithiazoles, 5-(thiazol-4′ and 5′-yl)-1,3,4- thiadiazoles , 5-(thien-2′-yl)-, 5-(furan-2′ and 3′-yl)-, thiadiazoles and related oxadiazoles, all with side chains containing dialkylamine terminal groups. The activities of these compounds as amplifiers of phleomycin -G are reported.
Synthesis of Some Novel Dinuclear Metal Complexes, Containing Both Square-Planar and Tetrahedral Metal Ions, by the Reactions of Coordinated Diamines with an α-Hydroxy Ketone
Authors: MacDermott TE
Published: September 2010

Reactions between tris (propane-1,3-diamine)nickel(II) salts and 3- hydroxy-3-methylbutan-2-one in the presence of zinc(II) or cadmium(II) halides yield a series of di -oxygen-bridged dinuclear products which contain the square-planar nickel(II) complex of a 12-membered ligand ring one of whose members is either a zinc(II) or cadmium(II) halide. These complexes are thermally very stable but may be hydrolysed by water to give a complex of the corresponding α- imino alcohol.
Crystal Structures of Bis(pyrrolidinedithiocarbamato)-nickel(II) and -copper(II) (Redeterminations)
Authors: Engelhardt LM , Patrick JM , White AH
Published: September 2010

Single-crystal X-ray redeterminations of the title compounds have been carried out at 295 K, by using diffractometer , rather than film data. [Ni(S2CN(CH2)4)2], (1), and [Cu(S2CN(CH2)4)2], (2), are isomorphous and triclinic, pī , with Z = 1, the metal atom being located on a crystallographic inversion centre. The structure of (1), a 7.470(2), b 7.972(3), c 6.325(3) Ǻ, α 103.17(3), β 93.48(3)°, γ 75.45(3)°, yielded R 0.038 for 1041 independent 'observed' reflections; for (2), a 7.477(3), b 8.057(2), c 6.373(1) Ǻ, α 104.77(1), β 94.06(2), γ 76.60(2)°, R was 0.033 for 1037 reflections. Ni-S are 2.214(1), 2.198(1) Ǻ; Cu-S are 2.312(1),
2.280(1) Ǻ.
Synthesis, Absolute Configuration and Local Anaesthetic Activity of the Enantiomers of α- and Β-Methylprocaine
Authors: Bell KH , Fullick G
Published: September 2010

Optically active forms of 1-( diethylaminomethyl )ethyl 4-aminobenzoate (α- methylprocaine ) (1) and 2-( diethylamino ) propyl 4-aminobenzoate (β- methylprocaine ) (2) of known absolute configuration have been prepared. The enantiomers show no stereoselectivity in conduction or infiltration anaesthesia.
Experimental and Theoretical-Study of Carbon-Fluorine Couplings in the NMR-Spectra of 2-Fluoroaryl Ketones
Authors: Contreras RH , Giribet CG , Natiello MA , Perez J , Rae ID , Weigold JA
Published: September 2010

Calculations by the IPPP-INDO method give the spin-spin coupling constants for the side-chain carbons, 3JCF and 4JCF, as 4.97 and 6.86 Hz respectively with substantial contributions to through-space coupling from the pathway CO-C-H…F. The observed values for 1-(2- fluorophenyl ) ethanone , 3.3 and 7.2 Hz, and for 1-(2,5- difluorophenyl ) ethanone , 3.7 and 7.3 Hz, are in good agreement with these predictions. Two compounds, a dihydroindenone and a naphthalenone, in which this pathway cannot be effective, show no fluorine coupling to the aliphatic carbon next to the carbonyl and the values of 3JCF are reduced to 2.2 and 2.5 Hz, consistent with the loss of a through-space Fermi contact term of the kind described above.
Complexes of Nickel(II) and Copper(II) With 5,5,7-Trimethyl-1,4-Diazepane. Preparation and Kinetics of Acid-Hydrolysis
Authors: Curtis NF
Published: September 2010

The cyclic diamine 5,5,7-trimethyl-1,4-diazepane, tmdz, is formed by borohydride reduction of 5,7,7-trimethyl-2,3,6,7-tetrahydro-1H-1,4- diazepine , which is formed by a rapid reaction between ethanediamine and 4-methylpent-3-en-2-one. Salts of the cations [Ni( tmdz )2]2+ and [Cu( tmdz )2]2+ were prepared, and their properties are reported. The kinetics of hydrolysis of [Ni( tmdz )2]2+ and [Cu( tmdz )2]2+ and bis (1,4- diazepane )nickel(II), [Ni( dach )2]2+, in aqueous HCl/NaCl media have been studied. Reaction rates are independent of acid concentration over the ranges used . Ni2+,0.1-1 mol l-1 H+ in 1 mol l-1 Cl -, kobs(25°C) = 9.1(1)×10-7 s-1, kobs(50°C) = 2.0(1)×10-5 s-1,ΔH‡96(2)kJ
mol-1,0.08-4 mol l-1, H+ in 4 mol l-1 Cl -, kobs (25°pC) = 2.0(3)°10-7 s-1. Cu2+, 0.04-1 mol l-1 H+, 1 mol l-1 Cl -, kobs
(25°C) = 0.028(2) s-1, for the displacement of the second ligand . [Ni( dach )2]2+, 0.1-1 mol l-1 H+, 1 mol l-1 Cl -, kobs (25°C) = 0.051(2) s-1. [Ni( tmdz )2]2+ reacts more rapidly with NaOH/edta : 1 mol l-1 NaOH , 0.1 mol l-1, Na2(edtaH2), kobs (25°C) = 7.3(3)×10-3 s-1, 0.5 mol l-1 NaOH , 0.1 mol l-1 Na2(edtaH2), kobs (25°C) = 4.5(3)×10-3 s-1.
Oxidations With Lead-Tetraacetate. VI. Oxidations of Benzimidazoles, Benzoxazoles and Benzothiazoles
Authors: Cole ER , Crank G , Sumantr i
Published: September 2010

Benzimidazole is slowly oxidized in the imidazole ring by lead tetraacetate to benzimidazol-2(3H)-one, 1-acetylbenzimidazol-2(3H)-one and N,N′-(o- phenylene ) bisacetamide . With excess oxidant, oxidation also occurs in the benzene ring at C5. Benzoxazole is much more reactive and gives a variety of products formed by oxidation of both rings. Benzothiazole is the least reactive system and suffers only minimal oxidation at C2 of the thiazole ring.
Structure in Nitrate Glasses - Nonrandom Ion Distribution in Glasses of the Type Mii(NO3)2/NH4NO3
Authors: James DW , Carrick MT
Published: September 2010

Several glasses of the nitrates of Mg2+, Cd2+ and Ca2+ with ammonium nitrate have been studied. The factors influencing the variation of the vibrational band associated with the symmetrical stretching motion are discussed. The profile for this vibrational band is component-band-analysed with the aid of time correlation functions and theta functions and it is shown that for all systems several band components are present. Some of these are clearly best described as arising from environments in which the anion is associated with cations of both charge types while other bands are more probably associated with essentially isotropic cation environments of one charge type. There is shown to be little contribution from hot bands in the band profile.
Synthesis of Acarnidines: Guanidinated Spermidine Homologs Through Imine Intermediates
Authors: Yorke SC , Blunt JW , Munro MHG , Cook JC , Rinehart KL
Published: September 2010

One of the naturally occurring acarnidines , N-(5-guanidinopentyl)-N-[3-(3-methylbut-2-enamido) propyl ] dodecanamide, together with 17 analogues containing different alkyl chain lengths in the triamine structure and the acyl side chain, have been synthesized by a versatile general method whose key features are formation of the secondary amine by reductive amination of an aldehyde and incorporation of the guanidine function in the last step. This general method affords high yields of selectively substituted unsymmetric triamines.