bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of the phenylurea hydrolases A and B: founding members of a novel amidohydrolase subgroup
Authors: Khurana Jeevan L. , Jackson Colin J. , Scott Colin , Pandey Gunjan , Horne Irene , Russell Robyn J. , Herlt Anthony , Easton Christopher J. , Oakeshott John G.
Published: November 2008

Mycobacterium brisbanense strain JK1, a bacterium capable of degrading the herbicide diuron, was isolated from herbicide-exposed soil. A gene/enzyme system with diuron hydrolase activity was isolated from this strain and named PUH (phenylurea hydrolase) B (puhB/PuhB) because of its close similarity to the previously characterized PUH A (puhA/PuhA). Both PUHs were heterologously expressed, purified and characterized. The PUHs were found to oligomerize as hexamers in solution, with each monomer containing a mononuclear Zn2+ active site. Sequence analysis showed that these enzymes belong to the metal-dependent amidohydrolase superfamily, although they contain a hitherto unreported Asn-X-His metal-binding motif and appear to form a novel sub-group within this superfamily. The effects of temperature and solvent on the enzymes were characterized. Determination of the kinetic parameters of the PUHs was used alongside Brønsted plots to develop a plausible catalytic mechanism, which is similar to that used by urease. In addition to the primary PUH activity, both enzymes are catalytically promiscuous, efficiently hydrolysing esters, carbamates and phosphotriesters. In fact, an analogue of diuron, in which the C–N bond was replaced by a C–O bond, was found to be turned over as efficiently as diuron, suggesting that the substrate specificity is predominantly determined by steric factors. The discovery of PuhA and PuhB on separate continents, and the absence of any other close homologues in the available sequence databases, poses a challenging question regarding the evolutionary origins of these enzymes.
Give the Poor Patients a Chance: Enhancing Access to Essential Medicines through Compulsory Licensing
Authors: Kuanpoth Jakkrit
Published: November 2008

The important relationship between pharmaceutical patents and problem of inaccessibility of medicines by poor nations is exemplified more clearly by the experiences of developing countries in Asia. Thailand is one of these developing countries which has the most experience of the negative impact of stronger patent protection. The paper provides a general view of the problem of the inaccessibility of lifesaving medicines in Thailand. It also discusses the attempts of the Thai Government to use an available legal measure (ie compulsory licensing) to control the abuse of pharmaceutical patent rights, and provides a theoretical and practical analysis of various legal issues relating to the use of the non-voluntary licensing scheme to improve access to essential medicines.
Theoretical and simulated models for an irreversible Otto cycle
Authors: Curto-Risso P. L. , Medina A. , Hernández A. Calvo
Published: November 2008

We show in this work that a finite-time-thermodynamics model of an irreversible Otto cycle is suitable to reproduce performance results of a real spark ignition heat engine. In order to test our model we have developed a computer simulation including a two-zone combustion model and compared the evolution of the performance parameters of the simulated engine as functions of the rotational speed (ω) with those obtained from a simple theoretical scheme including chemical reactions. A theoretical Otto cycle with irreversibilities arising from friction, heat transfer through the cylinder walls, and internal losses properly reproduces simulation results by considering extreme temperatures and mass inside the cylinder as functions of ω. Furthermore we obtain realistic values for the parameters characterizing global irreversibilities, their evolution with ω, and a clearer understanding of their physical origin not always well established in theoretical models.
A liquid waveguide based evanescent wave sensor integrated onto a microfluidic chip
Authors: Li X. C. , Wu J. , Liu A. Q. , Li Z. G. , Soew Y. C. , Huang H. J. , Xu K. , Lin J. T.
Published: November 2008

An evanescent wave sensor based on liquid waveguide is integrated onto a microfluidic chip. The structure of the liquid waveguide consists of three streams with two low refractive index fluids as cladding layers, which envelop a high refractive index fluid as a core layer along a microchannel. Light is coupled into the core layer, and a detected sample is injected into one cladding layer. The profile of the output light modal power is changed by varying the concentration of the sample. The sensor with a sensitivity of 275μm2l∕mol can be used for real-time, low-cost, and label-free measurements in a wide range of applications.
Band offsets between Si and epitaxial rare earth sesquioxides (RE2O3, RE=La,Nd,Gd,Lu): Effect of 4f-shell occupancy
Authors: Afanas’ev V. V. , Badylevich M. , Stesmans A. , Laha A. , Osten H. J. , Fissel A. , Tian W. , Edge L. F. , Schlom D. G.
Published: November 2008

Internal photoemission of electrons and holes into cubic Nd2O3 epitaxially grown on (100)Si reveals a significant contribution of Nd 4f states to the spectrum of the oxide gap states. In contrast to oxides of other rare earth (RE) elements (Gd, Lu) epitaxially grown in the same cubic polymorph, to hexagonal LaLuO3, and to polycrystalline HfO2, the occupied Nd 4f states produce an additional filled band 0.8eV above the O 2p derived valence band. The unoccupied portion of the Nd 4f shell leads to empty electron states in the energy range of 1eV below the RE 5d derived oxide conduction band. The exposed Nd 4f states suggest the possibility to use this metal and, possibly, other REs with low f-shell occupancy to control the interface band offsets by selective interface doping.
A cryogenic supersonic nozzle apparatus to study homogeneous nucleation of Ar and other simple molecules
Authors: Sinha Somnath , Laksmono Hartawan , Wyslouzil Barbara E.
Published: November 2008

We present a supersonic nozzle apparatus to study homogeneous nucleation of argon and other simple molecules. Experiments can be conducted with pure condensable vapor or with condensable vapor-carrier gas mixtures. The flow through the nozzle is continuous, and expansions typically start at temperatures T0 in the range of 100<T0/K<120, and pressures p0 in the range of 30<p0/kPa<36. The gas mixture is cooled using a tube and fin heat exchanger by evaporating liquid nitrogen on the tube side. The nozzle sidewalls are also cooled with liquid nitrogen to maintain them at a temperature ∼20 K higher than the stagnation temperature. Static pressure measurements detect the onset of condensation, and the other properties of the flow are derived by integrating the diabatic flow equations. We present sample experimental results for pure argon where at the onset of condensation, temperatures Ton range from 47.5<Ton/K<49.5 and pressures pon range from 4.2<pon/kPa<4.9.
Tunable bandgap structures of two-dimensional boron nitride
Authors: Li Jin , Gui Gui , Zhong Jianxin
Published: November 2008

Electronic structures of two-dimensional (2D) hexagonal boron nitride (h-BN) with different planar strain distributions have been studied using the first principles methods. We found that the 2D h-BN without strain has a large direct bandgap and its bandgap structure strongly depends on the strength and direction of the strain. The bandgap width can be reduced significantly under both symmetrical and asymmetrical strain distributions. Moreover, the bandgap feature exhibits strong anisotropic behaviors. The bandgap remains direct under large symmetrical tensile strain or asymmetrical tensile strain perpendicular to B–N bonds. However, a small amount of symmetrical compressive strain larger than 1.5% or asymmetrical tensile strain parallel to B–N bonds larger than 1.2% turns the direct bandgap into indirect. Our results indicate that optical and electronic transport properties of 2D h-BN can be effectively tuned by applying different planar forces, offering a unique route for designing nanoscale tunable ultrathin optoelectronic devices only one atomic layer thick.
Encapsulation of organic light-emitting devices using a perfluorinated polymer
Authors: Granstrom J. , Swensen J. S. , Moon J. S. , Rowell G. , Yuen J. , Heeger A. J.
Published: November 2008

Films of Cytop™, a perfluorinated polymer, are spin cast as a single barrier layer for evaluation of barrier properties on organic light-emitting devices and on Ca thin films. Cytop™ is water repellant, resulting in encapsulated organic light-emitting field effect transistors and organic light-emitting diodes (OLEDs), which remain active even after immersion into water or exposure to water droplets on the Cytop™ surface. OLEDs encapsulated with Cytop™ exhibit up to five times longer continuous operation under identical environmental and driving conditions compared with devices that are not encapsulated with Cytop™.
Field emission from open multiwall carbon nanotubes: A case of non-Fowler–Nordheim behavior.
Authors: Zestanakis P. A. , Xanthakis J. P.
Published: November 2008

Open multiwall carbon nanotubes (MWCNTs) have a non-Fowler–Nordheim (non-FN) emission characteristic, even after the cleaning process, in contrast to closed carbon nanotubes (CNTs), which become FN-like after the cleaning process. We have calculated the emitted current from open MWCNTs using our previously calculated transmission coefficients, which were derived by the use of a multidimensional WKB method. Our results reveal that the non-FN behavior of open CNTs should be attributed to the following two features of the two-dimensional (angle and distance dependent) tunneling potential V(r,θ). (a) V(r,θ) deviates from the approximately linear (with distance) potentials associated with planar surfaces with this nonlinearity having nothing to do with the image potential. (b) The individual walls of the MWCNTs essentially see different tunneling potentials due to the angle dependence of V(r,θ). From our calculations we also find that only a few layers of the open MWCNTs contribute to the current at low fields. At higher fields, more layers become active.
Toroidal self-consistent modeling of drift kinetic effects on the resistive wall mode
Authors: Liu Yueqiang , Chu M. S. , Chapman I. T. , Hender T. C.
Published: November 2008

A self-consistent kinetic model is developed to study the stability of the resistive wall mode in toroidal plasmas. This model is compared with other models based on perturbative approaches. The degree of the kinetic modification to the stability of the mode depends on the plasma configurations. Both stabilizing and destabilizing kinetic effects are observed. The nonperturbative approach, with a self-consistent inclusion of the eigenfunctions and the eigenvalues of the resistive wall mode, normally finds less stabilization than the perturbative approach.
Effects of the parallel electron dynamics and finite ion temperature on the plasma blob propagation in the scrape-off layer
Authors: Jovanović D. , Shukla P. K. , Pegoraro F.
Published: November 2008

A new three-dimensional model for the warm-ion turbulence at the tokamak edge plasma and in the scrape-off layer is proposed, and used to study the dynamics of plasma blobs in the scrape-off layer. The model is based on the nonlinear interchange mode, coupled with the nonlinear resistive drift mode, in the presence of the magnetic curvature drive, the density inhomogeneity, the electron dynamics along the open magnetic field lines, and the electron-ion and electron-neutral collisions. Within the present model, the effect of the sheath resistivity decreases with the distance from the wall, resulting in the bending and the break up of the plasma blob structure. Numerical solutions exhibit the coupling of interchange modes with nonlinear drift modes, causing the collapse of the blob in the lateral direction, followed by a clockwise rotation and radial propagation. The symmetry breaking, caused both by the parallel resistivity and the finite ion temperature, introduces a poloidal component in the plasma blob propagation, while the overall stability properties and the speed are not affected qualitatively.
Brownian escape and force-driven transport through entropic barriers: Particle size effect
Authors: Cheng Kuang-Ling , Sheng Yu-Jane , Tsao Heng-Kwong
Published: November 2008

Brownian escape from a spherical cavity through small holes and force-driven transport through periodic spherical cavities for finite-size particles have been investigated by Brownian dynamic simulations and scaling analysis. The mean first passage time and force-driven mobility are obtained as a function of particle diameter a, hole radius RH, cavity radius RC, and external field strength. In the absence of external field, the escape rate is proportional to the exit effect, (RH∕RC)(1−a∕2RH)3∕2. In weak fields, Brownian diffusion is still dominant and the migration is controlled by the exit effect. Therefore, smaller particles migrate faster than larger ones. In this limit the relation between Brownian escape and force-driven transport can be established by the generalized Einstein–Smoluchowski relation. As the field strength is strong enough, the mobility becomes field dependent and grows with increasing field strength. As a result, the size selectivity diminishes.
In situ nanocalorimetry of thin glassy organic films
Authors: León-Gutierrez E. , Garcia G. , Lopeandía A. F. , Fraxedas J. , Clavaguera-Mora M. T. , Rodríguez-Viejo J.
Published: November 2008

In this work, we describe the design and first experimental results of a new setup that combines evaporation of liquids in ultrahigh vacuum conditions with in situ high sensitivity thermal characterization of thin films. Organic compounds are deposited from the vapor directly onto a liquid nitrogen cooled substrate, permitting the preparation and characterization of glassy films. The substrate consists of a microfabricated, membrane-based nanocalorimeter that permits in situ measurements of heat capacity under ultrafast heating rates (up to 105 K/s) in the temperature range of 100–300 K. Three glass forming liquids—toluene, methanol, and acetic acid—are characterized. The spikes in heat capacity related to the glass-transition temperature, the fictive temperature and, in some cases, the onset temperature of crystallization are determined for several heating rates.
Study of surface passivation of strained indium gallium arsenide by vacuum annealing and silane treatment
Authors: Chin Hock-Chun , Wang Benzhong , Lim Poh-Chong , Tang Lei-Jun , Tung Chih-Hang , Yeo Yee-Chia
Published: November 2008

A study of the surface passivation of strained InGaAs using vacuum annealing and silane (SiH4) passivation was reported for the first time. X-ray photoelectron spectroscopy reveals the elimination of As–O bond after vacuum annealing and SiH4 surface passivation. Vacuum annealing eliminated poor quality native oxide on InGaAs surface, while a thin silicon interfacial layer was formed by SiH4 treatment, therefore effectively preventing the InGaAs surface from exposure to an oxidizing ambient during high-k dielectric deposition. Transmission electron micrograph confirmed the existence of a thin oxidized silicon layer between high-k dielectric and InGaAs. By incorporating this surface technology during gate stack formation, TaN/HfAlO/InGaAs metal-oxide-semiconductor capacitors demonstrate superior C-V characteristics with negligible frequency dispersion, small hysteresis, and interface state density as low as (3.5×1011)–(5.0×1011) cm−2 eV−1.
Relations among nonbridging oxygen, optical properties, optical basicity, and color center formation in CaO–MgO aluminosilicate glasses
Authors: Novatski A. , Steimacher A. , Medina A. N. , Bento A. C. , Baesso M. L. , Andrade L. H. C. , Lima S. M. , Guyot Y. , Boulon G.
Published: November 2008

In this study the relations among nonbridging oxygen (NBO), optical properties, optical basicity, and color center formation in CaO–MgO aluminosilicate glasses were studied. Samples containing (in mol %) 35.9–57.5 of CaO, 16–27.7 of Al2O3, 7.9–41.6 of SiO2, and 6.5–6.9 of MgO were measured by optical absorption and excitation, luminescence, and Raman spectroscopy. The results showed that when the SiO2 content was increased, the absorption edge shifted toward lower wavelengths and the bonds between O2− ions and cations became more covalent. These observations were confirmed by Raman results that showed a decrease in the number of NBO per silicon tetrahedron as a function of SiO2 content. The results indicate that the effects of higher NBO concentration are the narrowing of the band gap energy and the delocalization of O2− electrons, which facilitates the O2− electrons to be trapped by anion vacancies and, consequently, forming color centers. The relationship between color center formation and SiO2 content was confirmed by optical spectroscopic measurements under UV radiation.
Capture of nonmagnetic particles and living cells using a microelectromagnetic system
Authors: Aki Atsushi , Ito Osamu , Morimoto Hisao , Nagaoka Yutaka , Nakajima Yoshikata , Mizuki Toru , Hanajiri Tatsuro , Usami Ron , Maekawa Toru
Published: November 2008

We develop a microelectromagnetic system to trap nonmagnetic materials such as micropolystyrene particles and yeast cells in particular areas. We fabricate gold films, the width of the central narrow part is 22 μm, and flow an electric current through the films. We then apply an external uniform dc magnetic field to weaken the local magnetic field at the narrow part so that a nonuniform magnetic field is produced. We demonstrate that the particles, which are dispersed in magnetic fluid, are successfully trapped at the narrow part of the film. We evaluate the driving force acting on a microparticle in the nonuniform magnetic field and carry out a Stokesian dynamics simulation of the motion of the particles. We show that yeast cells are also trapped at the narrow part of the film. Finally, we fabricate multichannel microelectromagnets so that yeast cells are trapped at multiple points in the microelectromagnetic system. The present system may be applied to cell transfection on a cell microarray and, therefore, eventually contribute to progress in the identification and determination technologies of different drug targets and the functions of genes and proteins.
Conformational and microstructural characteristics of poly(L-lactide) during glass transition and physical aging
Authors: Pan Pengju , Zhu Bo , Dong Tungalag , Yazawa Koji , Shimizu Tadashi , Tansho Masataka , Inoue Yoshio
Published: November 2008

The glass transition and physical aging processes of poly(L-lactide) (PLLA) were studied by variable-temperature Fourier transform infrared (FTIR) spectroscopy and C13 solid-state NMR spectroscopy. The glass transition temperature (Tg) of PLLA can be well determined from the temperature-dependent FTIR intensity. Nearby Tg, a distinct change in the slope of spectral intensity versus temperature plot is detected. FTIR results suggest that the energy-favorable gauche-trans (gt) conformers rearrange into the less energy-favorable gauche-gauche (gg) counterparts with heating over the glass transition region, which becomes more distinct at temperature above Tg. Besides, the 1267 cm−1 band, which shows different trends of variation from the other bands upon heating, was assigned to be more sensitive to the νas(C–O–C)+δ(CH) vibration mode of the less energy-favorable gg conformers in PLLA. By comparing the FTIR spectra of the aged and deaged PLLA, it was demonstrated that the rearrangement from the high- to low-energy conformers, i.e., gg to gt, occurs with physical aging. C13 spin-lattice relaxation measurements indicate that the relaxation rate distribution broadens with aging, which agrees with the previous suggestion that the locally ordered domains are formed during physical aging. Because of the larger variation in the conformational state and microstructure, the FTIR intensities vary much more abruptly for the aged sample with heating to nearby Tg.
Fractional order Shapiro steps in superconducting nanowires
Authors: Dinsmore R. C. , Bae Myung-Ho , Bezryadin A.
Published: November 2008

We expose superconducting nanowires to microwave radiation in order to study phase lock-in effects in quasi-one-dimensional superconductors. For sufficiently high microwave powers a resistive branch with Shapiro steps appears in the voltage-current characteristics. At frequencies in the range of 0.9–4 GHz these steps are of integer order only. At higher frequencies steps of 1/2, 1/3, 1/4, and even 1/6 order appear. We numerically model this behavior using a multivalued current-phase relationship for nanowires.
Cutoff criteria of electronic partition functions and transport properties of atomic hydrogen thermal plasmas
Authors: Bruno D. , Capitelli M. , Catalfamo C. , Laricchiuta A.
Published: November 2008

Transport coefficients of equilibrium hydrogen plasma have been calculated by using different cutoffs of electronic partition functions and different sets of transport cross sections of electronically excited states. The selection of both the cutoff criterion and transport cross sections deeply affects the transport coefficients of the H, H+, e plasma mixture in the temperature range of 10 000–50 000 K and in the pressure interval of 1–1000 atm.
Competing interactions and complex magnetism at SrRuO3/SrMnO3 interfaces
Authors: Choi Y. , Tseng Y. C. , Haskel D. , Brown D. E. , Danaher D. , Chmaissem O.
Published: November 2008

The coupled interfacial Mn and Ru spin configurations in a SrRuO3(SRO)/SrMnO3(SMO) superlattice are investigated with x-ray resonant techniques. With an out-of-plane applied field H, a net Mn moment is induced opposite to (along) H below (above) SRO Curie temperature TC, due to changes in interfacial antiferromagnetic Ru–Mn coupling. In comparison with the Mn moment induced along an out-of-plane field below TC, the Mn moment induced along an in-plane field is five (three) times smaller below (above) TC, due to frustration in the Ru–Mn coupling. Despite its in-plane anisotropy, the G-type antiferromagnetic SMO favors out-of-plane over in-plane canting of Mn moments.
Profiles of flow discharged from vertical rotating pipes: A contrast between inviscid liquid and granular jets
Authors: Weidman P. D. , Kubitschek J. P. , Medina A.
Published: November 2008

The stability of viscous rotating liquid columns and their application to rotating viscous liquid jets aligned under gravity is reviewed. Experiments on stable viscous fluid flow discharged from rotating vertical pipes exhibit very weak contraction. We present an elementary liquid jet analysis to understand this phenomenon. Indeed, our inviscid model of a slender rotating inviscid liquid jet shows that rotation suppresses contraction. Next we study the comparable problem for granular flow. Our model for noncohesive granular flow emanating from a vertical pipe rotating about its central axis, valid for sufficiently large rotation rate, shows that the granular profiles blossom rather than contract. The profiles of both the liquid and granular jets depend on the same dimensionless parameters—an exit Froude number Fr0 and an exit swirl parameter χ0. The limitations of both models are discussed. Experimental data for granular jet profiles compare well with the collision-free granular flow model in its range of applicability. A criterion for the rotation rate at which particles adjacent to the inner wall of the rotating pipe cease to flow is also given and compared to experiment.
Electrical characteristics of contacts to thin film N-polar n-type GaN
Authors: Kim Hyunsoo , Ryou Jae-Hyun , Dupuis Russell D. , Lee Sung-Nam , Park Yongjo , Jeon Joon-Woo , Seong Tae-Yeon
Published: November 2008

The electrical characteristics of metallization contacts to a thin film N-polar n-type GaN layer fabricated by a laser lift-off process combined with a dry etching are investigated. It is shown that for Pt Schottky contacts, the Schottky barrier height of the N-polar GaN is 1.27eV, which is larger than that (1.23eV) of reference Ga-polar GaN. Ti∕Al Ohmic contacts to the N-polar GaN experience thermal degradation even at 400°C. Such annealing-induced degradation is explained in terms of the presence of the complex surface states of the N-polar GaN, which consists of impurities and process-induced donorlike and acceptorlike defects.
Antiphase ordering and surface phases in lithium aluminate
Authors: Vanfleet R. R. , Simmons J. A. , Hill D. W. , Chou M. M. C. , Chai B. H.
Published: November 2008

Antiphase domains are seen in single crystal gamma lithium aluminate (γ-LiAlO2) with 16.7 nm periodicity in the ⟨110⟩ direction. Alternate domains have a 12 [001] shift. Beta phase lithium aluminate (β-LiAlO2) is seen to form on the surface of the as-received wafers with an epitaxial strain limited relationship with the bulk γ phase. The orthorhombic β phase aligns with the a and b axes (0.528 and 0.630 nm) matching with the tetragonal γ phase’s a and c axes (0.5168 and 0.6268 nm). The γ and β phases are seen to have different etch rates. The β phase converts back to the γ phase above 450 °C.
Assessing the validity of modulation transfer function evaluation techniques with application to small area and scanned digital detectors
Authors: Price B. D. , Esbrand C. J. , Olivo A. , Gibson A. P. , Hebden J. C. , Speller R. D. , Royle G. J.
Published: November 2008

A novel prototype step and shoot x-ray system, the intelligent imaging system (I-Imas), has been developed in the UCL Radiation Physics laboratories. The system uses collimators to split the beam into two: the first, “scout” beam, strongly attenuated, identifies regions of interest in the image. This information is then fed back to the system so that the intensity of the second beam is modulated to optimize the dose distribution—i.e., “interesting” regions of the sample receive a higher dose, whereas other regions receive a lower one. Such systems may be capable of improved diagnostic capability at the same overall patient dose levels as typical when using large area digital plates. This acquisition mode means that large overall images are obtained by aligning many smaller images. This paper investigates the effects that this acquisition modality has on the overall spatial resolution of the system. We review different modulation transfer function (MTF) evaluation techniques and those shown to be optimal are used in the investigation of two considerations key to such a system: (i) whether there is a minimum size sensor whose MTF can accurately be determined using these techniques and (ii) whether the MTF of the large overall image differs significantly from those of the many constituent images. As the use of step and shoot systems is becoming more and more widespread, both are important considerations. We found that, for a fixed pixel pitch, the MTF is determined marginally less accurately the smaller the sensor area, with the perceived resolution varying by up to 0.1 lp/mm. It was also found that use of such a step and shoot technique does cause a very small overall degradation in resolution. The resolution of overall images was calculated to be 0.1 lp/mm lower than that of the individual images acquired.
Graphene: A perfect nanoballoon
Authors: Leenaerts O. , Partoens B. , Peeters F. M.
Published: November 2008

We have performed a first-principles density functional theory investigation of the penetration of helium atoms through a graphene monolayer with defects. The relaxation of the graphene layer caused by the incoming helium atoms does not have a strong influence on the height of the energy barriers for penetration. For defective graphene layers, the penetration barriers decrease exponentially with the size of the defects but they are still sufficiently high that very large defects are needed to make the graphene sheet permeable for small atoms and molecules. This makes graphene a very promising material for the construction of nanocages and nanomembranes.
Mechanism analysis of improved corona-resistant characteristic in polyimide/TiO2 nanohybrid films
Authors: Zha Jun-Wei , Song Hong-Tao , Dang Zhi-Min , Shi Chang-Yong , Bai Jinbo
Published: November 2008

Polyimide/TiO2 nanohybrid films with good corona resistance were prepared by using in situ dispersive polymerization. Effects of the concentration of nano-TiO2 fillers and the corona aging time on the dielectric properties of the films were explored. Results showed that the corona resistance of the hybrid films could be improved with increasing the concentration of TiO2 fillers, and the corona resistance was dependent on the dielectric permittivity of the hybrid films. The mechanism of the corona resistance was also discussed by analyzing the change in electric field and the electron action of TiO2 fillers based on the Fermi–Dirac statistic.
Charge states of vacancies in germanium investigated by simultaneous observation of germanium self-diffusion and arsenic diffusion
Authors: Naganawa Miki , Shimizu Yasuo , Uematsu Masashi , Itoh Kohei M. , Sawano Kentarou , Shiraki Yasuhiro , Haller Eugene E.
Published: November 2008

Diffusion of germanium (Ge) and arsenic (As) has been investigated simultaneously using As-implanted Ge isotope superlattices. No transient enhanced diffusion of As that could have arisen by the implantation damage is observed. A quadratic dependence of the Ge self-diffusion on the carrier concentration due to the Fermi level effect is observed. A precise reproduction of the Ge and As diffusion profiles by a numerical simulator lets us conclude that doubly negatively charged vacancies are the dominant point defects responsible for more than 95% of the self-diffusion in intrinsic Ge and this fraction increases even further in n-type Ge.
Ultrafast laser ablation of metals with a pair of collinear laser pulses
Authors: Amoruso S. , Bruzzese R. , Wang X. , Xia J.
Published: November 2008

We investigated the process of ultrafast laser ablation of metallic targets induced by a pair of identical laser pulses, with either p or s polarizations, temporally delayed from ≈1 ps to a few nanoseconds. We used fast ion probe diagnostics to characterize the ion plume at the moderate laser intensity (≈1012 W/cm2) typically employed in ultrafast laser deposition and material processing. We observed a consistent time-correlated enhancement of the ion yield and velocity, which lends itself to an interesting and useful method for manipulating ablation plasma characteristics. The mechanisms producing this feature are also discussed.
Surface states and origin of the Fermi level pinning on nonpolar GaN(11¯00) surfaces
Authors: Ivanova L. , Borisova S. , Eisele H. , Dähne M. , Laubsch A. , Ebert Ph.
Published: November 2008

GaN ( 1 1 ¯ 00 ) cleavage surfaces were investigated by cross-sectional scanning tunneling microscopy and spectroscopy. It is found that both the N and Ga derived intrinsic dangling bond surface states are outside of the fundamental band gap. Their band edges are both located at the Γ¯ point of the surface Brillouin zone. The observed Fermi level pinning at 1.0 eV below the conduction band edge is attributed to the high step and defect density at the surface but not to intrinsic surface states.
Ataxia with loss of Purkinje cells in a mouse model for Refsum disease
Authors: Ferdinandusse Sacha , Zomer Anna W. M. , Komen Jasper C. , van den Brink Christina E. , Thanos Melissa , Hamers Frank P. T. , Wanders Ronald J. A. , van der Saag Paul T. , Poll-The Bwee Tien , Brites Pedro
Published: November 2008

Refsum disease is caused by a deficiency of phytanoyl-CoA hydroxylase (PHYH), the first enzyme of the peroxisomal α-oxidation system, resulting in the accumulation of the branched-chain fatty acid phytanic acid. The main clinical symptoms are polyneuropathy, cerebellar ataxia, and retinitis pigmentosa. To study the pathogenesis of Refsum disease, we generated and characterized a
Phyh
knockout mouse. We studied the pathological effects of phytanic acid accumulation in
Phyh
−/−
mice fed a diet supplemented with phytol, the precursor of phytanic acid. Phytanic acid accumulation caused a reduction in body weight, hepatic steatosis, and testicular atrophy with loss of spermatogonia. Phenotype assessment using the SHIRPA protocol and subsequent automated gait analysis using the CatWalk system revealed unsteady gait with strongly reduced paw print area for both fore- and hindpaws and reduced base of support for the hindpaws. Histochemical analyses in the CNS showed astrocytosis and up-regulation of calcium-binding proteins. In addition, a loss of Purkinje cells in the cerebellum was observed. No demyelination was present in the CNS. Motor nerve conduction velocity measurements revealed a peripheral neuropathy. Our results show that, in the mouse, high phytanic acid levels cause a peripheral neuropathy and ataxia with loss of Purkinje cells. These findings provide important insights in the pathophysiology of Refsum disease.
Prefoldin 6 is required for normal microtubule dynamics and organization in
Arabidopsis
Authors: Gu Ying , Deng Zhiping , Paredez Alexander R. , DeBolt Seth , Wang Zhi-Yong , Somerville Chris
Published: November 2008

Newly translated tubulin molecules undergo a series of complex interactions with nascent chain-binding chaperones, including prefoldin (PFD) and chaperonin-containing TCP-1 (CCT). By screening for oryzalin hypersensitivity, we identified several mutants of
Arabidopsis
that have lesions in PFD subunits. The
pfd6–1
mutant exhibits a range of microtubule defects, including hypersensitivity to oryzalin, defects in cell division, cortical array organization, and microtubule dynamicity. Consistent with phenotypic analysis, proteomic analysis indicates several isoforms of tubulins were reduced in
pfd6–1
. These results support the concept that the function of microtubules is critically dependent on the absolute amount of tubulins.
In vivo efficacy of the Bcl-2 antagonist ABT-737 against aggressive Myc-driven lymphomas
Authors: Mason Kylie D. , Vandenberg Cassandra J. , Scott Clare L. , Wei Andrew H. , Cory Suzanne , Huang David C. S. , Roberts Andrew W.
Published: November 2008

Deregulated Myc expression drives many human cancers, including Burkitt's lymphoma and a highly aggressive subset of diffuse large cell lymphomas. Myc-driven tumors often display resistance to chemotherapeutics because of acquisition of mutations that impair the apoptosis pathway regulated by the Bcl-2 protein family. Given the need to identify new therapies for such lymphomas, we have evaluated the efficacy of ABT-737, a small molecule that mimics the action of the BH3-only proteins, natural antagonists of the prosurvival Bcl-2 proteins. ABT-737 selectively targets certain prosurvival proteins (Bcl-2, Bcl-x
L
, and Bcl-w) but not others (Mcl-1 and A1). We treated mice transplanted with lymphomas derived either from Eμ-
myc
transgenic mice or Eμ-
myc
mice that also expressed an Eμ-
bcl
-2 transgene. As a single agent, ABT-737 significantly prolonged the survival of mice transplanted with the
myc
/
bcl
-2 lymphomas but was ineffective for the
myc
lymphomas, probably because of the relatively higher Mcl-1 levels found in the latter. Strikingly, when combined with low-dose cyclophosphamide, ABT-737 produced sustained disease-free survival of all animals transplanted with two of three
myc
/
bcl
-2 lymphomas tested. The combination therapy was also more effective against some
myc
lymphomas than treatment with either agent alone. Our data suggest that antagonism of Bcl-2 with small organic compounds is an attractive approach to enhance the efficacy of conventional therapy for the treatment of Myc-driven lymphomas that over-express this prosurvival molecule.
‘Well, I answer it by simply inviting you to look at the evidence’
Authors: Fetzer Anita , Bull Peter
Published: November 2008

In the discourse of political interviews, references to participants can be expressed explicitly by proper nouns and forms of address, and they can be expressed implicitly by personal pronouns and other indexical expressions. The meaning of personal pronouns is context-dependent and retrievable only by inference, and therefore is less determinate. Furthermore, it can shift according to the status of the participants in interaction. This may occur both in terms of social roles and in terms of roles in talk and footing. In this context, an analysis was conducted of televised political interviews broadcast during the 1997 and 2001 British general elections and just before the war with Iraq in 2003. Question-response sequences were identified in which politicians made use of pronominal shifts as a form of equivocation. These sequences were analyzed in the context of Bavelas et al.s (1990) theory of equivocation and Goffmans (1981) concept of footing. The polyvalent function of pronominal shifts, their potential perlocutionary effects and strategic advantages are discussed.
What message does ‘send a message’ send?
Authors: Emanatian Michele , Delaney David
Published: November 2008

The violent acts of post-modern war are sometimes represented as long-distance communication. This paper examines the phrasesend a messageand others like it when used to refer to bombings, firing missiles, shooting civilians, etc. The metonymic reduction of killing and destroying to communication promotes message-sending as the single goal of a military enterprise. We provide relevant historical, cultural and political contexts that account for this increasingly prevalent framing: the imperatives of justifying aggressive war in a Post-Nuremburg international legal order; the emergence and intensification of message culture; and the increased strategic importance of perception management and information warfare. The paper includes a richly illustrated analysis of the metonymic structure ofsend a messageand its relationship to the common, well-studied metaphor for communication, the conduit. We argue that the use ofsend a messageto describe acts of violence does more than simply euphemize: it positions the message-senders as rational agents engaged in communicative action; and it displaces responsibility for suffering onto those who fail to get the message.
Poriadok and Bardak (Order and Chaos)
Authors: Bowden Zachary A.
Published: November 2008

This article argues that Russias various neo-fascist and ultra-nationalist groups are articulating a populism-in-formation around the signifiers order and people, and through the narrative of mischief. The process of signification and context are added to Ernesto Laclaus understanding of the process and politics of the articulation of hegemony. Texts, modes, symbols and narratives of various neo-fascist and ultra-nationalist groups are employed and analyzed to suggest the populism-in-formation that Russian neo-fascism represents. In concluding, the paper suggests that Russias National Bolshevik Party, insofar as they articulate a discourse that mobilizes resonant versions of order and people, and as their narrative mode highlights the mischievous version of masculinity which is dominant in Russian culture and politics, represents the potentiality of Russian neo-fascism to articulate a hegemonic populism.
Final nasal variation in Merida, Yucatan
Authors: Michnowicz Jim
Published: November 2008

This article investigates the linguistic and social constraints on final nasal variation in Yucatan Spanish (YS), based on data collected in Merida, Yucatan. Absolute final nasals in YS may surface variably as: [n], [ŋ], ø or [m] (e.g. pan → [pám], ‘bread’). The results reveal a distribution of final nasal realization unique to YS, as well as detail its patterning throughout the community. Unlike some previous findings, the data under investigation here demonstrate [n] to be the preferred nasal variant, accounting for 60% of tokens. Regional variant [m] accounts for 25%, while [ŋ] and ø were infrequent variants, arising 8% and 5% of the time, respectively. Standard [n] occurs mostly among older speakers and Spanish monolinguals. Bilabial [m], however, is a recent innovation, led by younger speakers, women, and Mayan-Spanish bilinguals. The realization [m] may serve as a marker of regional identity for some speakers. For others, though, this variant is becoming a linguistic stereotype, as suggested by qualitative data from speaker comments and instances of [m] in the popular culture, including on internet websites.
Subtitling8 Milein three languages
Authors: Taivalkoski-Shilov Kristiina
Published: November 2008

This article argues that when striving for quality in subtitling, special attention should be paid to the requirements of competence not only when recruiting translators, but also when recruiting local managers and subtitling co-ordinators. The findings are based on a stylistic comparison of the Finnish, French and Russian subtitled versions of8 Mile, a film that tells about Eminem’s early breakthrough as a rap artist (UIP, 2002). The rap sections of the film present many ‘text-specific translation problems’ (Nord), which become even more troublesome in the context of subtitling, as the translator has space for less text. The worldwide subtitling and dubbing of8 Milewas an especially well-supervised procedure. The translators were given a lot of material support (e.g., a detailed ‘dialogue list’) but their work was also strictly controlled and limited. According to this study, the severe policy of some local UIP offices may have hindered the quality of subtitling in some countries.
Democracy & its Discontents: Vigilantism, Sovereignty & Human Rights in South Africa
Authors: Buur Lars
Published: November 2008

This article argues that due to the particular position of crime in South Africa, the resurgence of vigilantism needs to be re-evaluated in light of the country's attempt at institutionalising human rights as the new society's founding values. Because many township dwellers see vigilantes as their protection against crime, vigilantism should be seen as a criticism of and a comment on human rights as the new expression of the country's most intimate values. The article begins by introducing an ethnographic case study of a vigilante group from Port Elizabeth's townships, which has become incorporated as an official ‘Safety and Security’ structure under the Community Policing Forum. The article suggests that fighting crime relates to wider questions of the perceived need for discipline and corporal punishment in response to the erosion of social authority.
Doing Science, Writing Science
Authors: Schickore Jutta
Published: November 2008

This article identifies a fundamental distinction in scientific practice: the mismatch between what scientists do and what they state they did when they communicate their findings in their publications. The insight that such a mismatch exists is not new. It was already implied in Hans Reichenbach's distinction between the contexts of discovery and justification, and it is taken for granted across the board in philosophy of science and science studies. But while there is general agreement that the mismatch exists, the epistemological implications of that mismatch are not at all clear. Philosophers, historians, and sociologists of different stripes have expressed widely different views about how one should understand and interpret the relation between what scientists do and what they state they did. This article surveys a number of approaches to the mismatch. Based on this survey, I offer an assessment of the epistemological significance of the mismatch and identify the major meta-epistemological challenges that it poses for the analysis of scientific practice.
ProtorP: a protein–protein interaction analysis server
Authors: Reynolds Christopher , Damerell David , Jones Susan
Published: November 2008

Summary: The PROTORP server analyses protein–protein associations in 3D structures. The server calculates a series of physical and chemical parameters of the protein interaction sites that contribute to the binding energy of the association. These parameters include, size and shape, intermolecular bonding, residue and atom composition and secondary structure contributions. The server is flexible, in that it allows users to analyse individual protein associations or large datasets of associations deposited in the PDB, or upload and analyse proprietary files. The properties calculated can be compared with parameter distributions for non-homologous datasets of different classes of protein associations provided on the server website. The server provides an efficient way of characterizing protein–protein associations of new or existing proteins, and a means of putting these values in the context of previously observed associations.

Availability:  http://www.bioinformatics.sussex.ac.uk/protorp

Contact:  s.jones@sussex.ac.uk
Associations Between Vrs1 Alleles and Grain Quality Traits in Spring Barley Hordeum vulgare L.
Authors: Turuspekov Y. , Martin J. M. , Bowman J. G. P. , Beecher B. S. , Giroux M. J.
Published: November 2008

Barley head row type is a major trait affecting end‐use quality. Six‐rowed forms emerged due to mutations in the Vrs1 gene in two‐rowed barleys. Whether barley is two (Vrs1) or six rowed (vrs1) directly affects a wide range of morphological traits related to seed yield and grain quality. Vrs1 has been cloned and encodes a homeodomain transcription factor with a linked leucine zipper motif. To test the association between Vrs1 alleles and grain quality, we characterized the Vrs1 alleles among a well‐described collection of 81 spring barley accessions selected for divergence in head type and dry matter digestibility (DMD). The results indicated that the majority of two‐rowed barleys have the Vrs1.b3‐1 allele and the majority of six‐rowed barleys carry the vrs1.a1‐8 allele. In comparison with two‐rowed barleys, six‐rowed barleys were more variable in grain hardness. This divergence in hardness values was associated with specific vrs1 alleles, with barley accessions carrying the less severe amino acid missense mutation VRS1.a3‐1 isoform being softer and having higher DMD than those accessions carrying the more common VRS1.a1‐1 amino acid frameshift isoform. The assignment of six‐rowed barley cultivars to different vrs1 allele groups may prove beneficial for the selection of specific grain‐quality parameters.
Assessing Fermentation Quality of Grain Sorghum for Fuel Ethanol Production Using Rapid Visco‐Analyzer
Authors: Zhao Renyong , Bean Scott , Wu Xiaorong , Wang Donghai
Published: November 2008

The Rapid Visco‐Analyzer (RVA) was used to characterize the pasting properties of 68 sorghum grains with a standard 23‐min temperature profile. The results showed a strong linear relationship between ethanol yield and final viscosity as well as setback. Ethanol yield increased as final viscosity decreased. A modified RVA procedure (10 min) with an application of α‐amylase was developed to simulate the liquefaction step in dry‐grind ethanol production. There was a remarkable difference in mashing properties among the sorghum samples with the normal dosage of α‐amylase. The sorghum samples which were difficult to liquefy in the mashing step had much higher peak viscosities than the samples that were easily liquefied. The results also showed that the relationship between conversion efficiency and mashing property was significant. Tannins cause high mash viscosities. There was a strong linear relationship between tannin content and final viscosity as well as peak viscosity. The modified RVA procedure is applicable not only for characterization of mashing properties but also for optimization of α‐amylase doses for starch liquefaction.