bluuebunny/crossref_metadata_2025 huggingface dataset:
Normoxic Resuscitation after Cardiac Arrest Protects against Hippocampal Oxidative Stress, Metabolic Dysfunction, and Neuronal Death
Authors: Vereczki Viktoria , Martin Erica , Rosenthal Robert E , Hof Patrick R , Hoffman Gloria E , Fiskum Gary
Published: October 2005

Resuscitation and prolonged ventilation using 100% oxygen after cardiac arrest is standard clinical practice despite evidence from animal models indicating that neurologic outcome is improved using normoxic compared with hyperoxic resuscitation. This study tested the hypothesis that normoxic ventilation during the first hour after cardiac arrest in dogs protects against prelethal oxidative stress to proteins, loss of the critical metabolic enzyme pyruvate dehydrogenase complex (PDHC), and minimizes subsequent neuronal death in the hippocampus. Anesthetized beagles underwent 10 mins ventricular fibrillation cardiac arrest, followed by defibrillation and ventilation with either 21% or 100% O2. At 1 h after resuscitation, the ventilator was adjusted to maintain normal blood gas levels in both groups. Brains were perfusion-fixed at 2 h reperfusion and used for immunohistochemical measurements of hippocampal nitrotyrosine, a product of protein oxidation, and the E1α subunit of PDHC. In hyperoxic dogs, PDHC immunostaining diminished by approximately 90% compared with sham-operated dogs, while staining in normoxic animals was not significantly different from nonischemic dogs. Protein nitration in the hippocampal neurons of hyperoxic animals was 2–3 times greater than either sham-operated or normoxic resuscitated animals at 2 h reperfusion. Stereologic quantification of neuronal death at 24 h reperfusion showed a 40% reduction using normoxic compared with hyperoxic resuscitation. These results indicate that postischemic hyperoxic ventilation promotes oxidative stress that exacerbates prelethal loss of pyruvate dehydrogenase and delayed hippocampal neuronal cell death. Moreover, these findings indicate the need for clinical trials comparing the effects of different ventilatory oxygen levels on neurologic outcome after cardiac arrest.
ERK1/2 Inhibition Attenuates Cerebral Blood Flow Reduction and Abolishes ETB and 5-HT1B Receptor Upregulation after Subarachnoid Hemorrhage in Rat
Authors: Beg Saema AS , Hansen-Schwartz Jacob A , Vikman Petter J , Xu Cang-Bao , Edvinsson Lars IH
Published: October 2005

Upregulation of endothelin B (ETB) and 5-hydroxytryptamine 1B (5-HT1B) receptors via transcription has been found after experimental subarachnoid hemorrhage (SAH), and this is associated with enhanced phosphorylation of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (ERK1/2). In the present study, we hypothesized that inhibition of ERK1/2 alters the ETB and 5-HT1B receptor upregulation and at the same time prevents the sustained cerebral blood flow (CBF) reduction associated with SAH. The ERK1/2 inhibitor SB386023-b was injected intracisternally in conjunction with and after the induced SAH in rats. At 2 days after the SAH, cerebral arteries were harvested for quantitative real-time polymerase chain reaction, immunohistochemistry and analysis of contractile responses to endothelin-1 (ET-1; ETA and ETB receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT1 receptor agonist) in a sensitive myograph. To investigate if ERK1/2 inhibition had an influence on the local and global CBF after SAH, an autoradiographic technique was used. At 48 h after induced SAH, global and regional CBF were reduced by 50%. This reduction was prevented by treatment with SB386023-b. The ERK1/2 inhibition also decreased the maximum contraction elicited by application of ET-1 and 5-CT in cerebral arteries compared with SAH. In parallel, ERK1/2 inhibition downregulated ETB and 5-HT1B receptor messenger ribonucleic acid and protein levels compared with the SAH. Cerebral ischemia after SAH involves vasoconstriction and subsequent reduction in the CBF. The results suggest that ERK1/2 inhibition might be a potential treatment for the prevention of cerebral vasospasm and ischemia associated with SAH.
Evaluated Kinetic Data for Combustion Modeling: Supplement II
Authors: Baulch D. L. , Bowman C. T. , Cobos C. J. , Cox R. A. , Just Th. , Kerr J. A. , Pilling M. J. , Stocker D. , Troe J. , Tsang W. , Walker R. W. , Warnatz J.
Published: October 2005

This compilation updates and expands two previous evaluations of kinetic data on elementary, homogeneous, gas phase reactions of neutral species involved in combustion systems [J. Phys. Chem. Ref Data 21, 411 (1992); 23, 847 (1994)]. The work has been carried out under the auspices of the IUPAC Commission on Chemical Kinetics and the UK Engineering and Physical Sciences Research Council. Individual data sheets are presented for most reactions but the kinetic data for reactions of C2, C, ethyl, i-propyl, t-butyl, and allyl radicals are summarized in tables. Each data sheet sets out relevant thermodynamic data, experimental kinetic data, references, recommended rate parameters with their error limits and a brief discussion of the reasons for their selection. Where appropriate the data are displayed on an Arrhenius diagram or by fall-off curves. Tables summarizing the recommended rate data and the thermodynamic data for the reactant and product species are given, and their sources referenced. As in the previous evaluations the reactions considered relate largely to the combustion in air of organic compounds containing up to three carbon atoms and simple aromatic compounds. Thus the data base has been expanded, largely by dealing with a substantial number of extra reactions within these general areas.
Structure and conformation properties of 1-alkyl-3-methylimidazolium halide ionic liquids: A density-functional theory study
Authors: Wang Yong , Li Haoran , Han Shijun
Published: October 2005

The structures and conformational properties of 1-alkyl-3-methylimidazolium halide ionic liquids have been studied with a Becke’s 3 Parameter functional method. The interaction mechanisms between the cation and the anion in 1-ethyl-3-methylimidazolium (Emim+) halide and 1-butyl-3-methylimidazolium (Bmim+) halide ionic liquids were investigated using 6-31G*, 6-31++G**, and 6-311++G** basis sets. Forty structures of different ion pairs were optimized and geometrical parameters of them have been discussed in details. Halide ions (Cl− or Br−) have been gradually placed in different regions around imidazolium cation and the interaction energies between the anion and the cation have been calculated. Theoretical results indicate that there are four activity regions in the vicinity of the imidazolium cations, in these regions the imidazolium cations and the halide anions formed stable ion pairs. Imidazolium cations can form hydrogen bond interactions with one, two or three but no more than three nearest halide anions. The halide ions are situated in hydrogen bond positions rather than at random.
Replica Ornstein-Zernike theory of adsorption in a templated porous material: Interaction site systems
Authors: Sarkisov Lev , Van Tassel Paul R.
Published: October 2005

Molecular templating offers the possibility of porous materials whose selectivity rivals the molecular recognition observed in nature. The design of templated materials requires a molecular understanding of the templating effect on the material structure and performance. We present here a theoretical description of adsorption in a model templated porous material. Our model material is a quenched, equilibrated mixture of template and matrix molecular species where the template component has been subsequently removed. We propose a set of site-site [i.e., reference interaction site model (RISM)] replica Ornstein-Zernike equations relating the correlation functions of template, matrix, and adsorbing fluid molecules. To test this approach, we focus here on systems interacting via hard-sphere site-site potentials and employ a Percus-Yevick closure. We consider chain and cluster species composed of up to five spheres and observe a range of effects associated with template structure, including higher affinity toward, and enhanced templating by, compact cluster molecules. We assess these effects by grand canonical Monte Carlo simulation and discuss their implication to the design of templated molecular recognition materials.
Isomers of NCO2: IR-absorption spectra of ONCO in solid Ne
Authors: Wu Yu-Jong , Lee Yuan-Pern
Published: October 2005

Irradiation of a Ne matrix sample containing NO and CO near 4K with an ArF excimer laser at 193nm yielded new lines at 2045.1 and 968.0cm−1 that were depleted upon secondary photolysis at 308nm. These lines are assigned to CO stretching and mixed stretching modes of ONCO, based on results of N15-, C13-, and O18-isotopic experiments and quantum-chemical calculations. These calculations using density-functional theory (B3LYP and PW91PW91/aug-cc-pVTZ) predict five stable isomers of NCO2: ONCO, NCOO, N-cyc-CO2, CNOO, and cyc-CNOO, listed in order of increasing energy. According to B3LYP calculations, ONCO has a trans configuration, with bond angles of ∠ONC≅136.3° and ∠NOC≅160.7°. Calculated vibrational wave numbers, IR intensities, N15-, C13-, and O18-isotopic shifts for ONCO agree satisfactorily with experimental results. ONCO was formed from reaction of CO with NO in its excited state.
Direct-potential-fit analysis of new infrared and UV/visible AΣ+1-XΣ+1 emission spectra of AgH and AgD
Authors: Le Roy Robert J. , Appadoo Dominique R. T. , Anderson Kevin , Shayesteh Alireza , Gordon Iouli E. , Bernath Peter F.
Published: October 2005

New high-resolution infrared and UV/visible spectra of Ag107H, Ag109H, Ag107D, and Ag109D have been recorded with a Fourier transform spectrometer. The new line positions are combined with published microwave and older electronic AΣ+1-XΣ+1 data and used, first in a decoupled analysis of the X state alone, and then in a global multi-isotopologue analysis which yields comprehensive descriptions of both the XΣ+1 and AΣ+1 states of all four isotopologues of AgH. While the A state was long believed to be heavily perturbed, it is shown that its irregular spectrum merely reflects an unusual potential function shape. A direct fit of all data to appropriate radial Hamiltonians yields analytic potential-energy functions and Born-Oppenheimer breakdown radial functions for the ground XΣ+1 and AΣ+1 states.
Continuum formulation of the Scheutjens-Fleer lattice statistical theory for homopolymer adsorption from solution
Authors: Mavrantzas Vlasis G. , Beris Antony N. , Leermakers Frans , Fleer Gerard J.
Published: October 2005

Homopolymer adsorption from a dilute solution on an interacting (attractive) surface under static equilibrium conditions is studied in the framework of a Hamiltonian model. The model makes use of the density of chain ends n1,e and utilizes the concept of the propagator G describing conformational probabilities to locally define the polymer segment density or volume fraction φ; both n1,e and φ enter into the expression for the system free energy. The propagator G obeys the Edwards diffusion equation for walks in a self-consistent potential field. The equilibrium distribution of chain ends and, consequently, of chain conformational probabilities is found by minimizing the system free energy. This results in a set of model equations that constitute the exact continuum-space analog of the Scheutjens-Fleer (SF) lattice statistical theory for the adsorption of interacting chains. Since for distances too close to the surface the continuum formulation breaks down, the continuum model is here employed to describe the probability of chain configurations only for distances z greater than 2l, where l denotes the segment length, from the surface; instead, for distances z⩽2l, the SF lattice model is utilized. Through this novel formulation, the lattice solution at z=2l provides the boundary condition for the continuum model. The resulting hybrid (lattice for distances z⩽2l, continuum for distances z>2l) model is solved numerically through an efficient implementation of the pseudospectral collocation method. Representative results obtained with the new model and a direct application of the SF lattice model are extensively compared with each other and, in all cases studied, are found to be practically identical.
DNA linker controlled single electron tunneling behavior of nanoparticle assembly
Authors: Lee Jae-Hyun , Cheon Jinwoo , Lee Sun Bae , Chang Young-Wook , Kim Sung-In , Yoo Kyung-Hwa
Published: October 2005

We report an efficient method for the fabrication of a single electron transistor (SET) using DNA-assisted assembly of nanoparticles. In this method, the DNA molecules function not only as the assembler, but also as the modulator for the electron tunneling behaviors of single electron transistors. A study of the assembly between an Au nanoparticle (∼10nm) and various lengths of DNA molecules confirms the effectiveness of this method in creating a SET. Most devices exhibited clear single electron effects.
Ab initio relativistic calculation of the RbCs molecule
Authors: Kotochigova S. , Tiesinga E.
Published: October 2005

We apply the relativistic configuration-interaction valence-bond method to calculate various characteristics of the alkali-metal RbCs dimer. These include the electronic potentials and transition dipole moments between the ground and first excited states and permanent dipole moments of the XΣ+1 and aΣ+3 states of the ground configuration. In addition, we estimate the lifetime of the rovibrational levels of the X state due to blackbody radiation. These data can help experimentalists to optimize photoassociative formation of ultracold RbCs molecules and their longevity in a trap or in an optical lattice. Extended basis sets, constructed from Dirac-Fock and Sturm’s orbitals, have been used to ensure convergence of our calculations. We compare our data with other theoretical and experimental results when they were available.
Quantitative analysis of a closed photoacoustic cell that uses a high compliance piezoelectric transducer
Authors: Hodgkinson Jane , Johnson Mark , Dakin John P.
Published: October 2005

A treatment of the operation of low-frequency closed photoacoustic cells is presented, which considers the compliance of various cell elements. The optimum detector, according to our predictions, has a sensor whose compliance is large compared to that of the fluid enclosed by the cell. A simple photoacoustic cell has been built, incorporating a thin-walled piezoelectric cylinder. It was used to test the theory, and demonstrate photoacoustic detection of an absorber in aqueous solution, excited by a low-power 678 nm laser diode modulated at 110 Hz. We have detected absorbances as low as approximately 3×10−3cm−1 (signal-to-noise ratio=1), corresponding to the absorption of light with a modulated power of 50μWrms.
Simple model for time-dependent dielectric breakdown in inter- and intralevel low-k dielectrics
Authors: Lloyd J. R. , Liniger E. , Shaw T. M.
Published: October 2005

A simple physical model is applied to time-dependent dielectric breakdown failure in ultralow-k(k=2.3) interlevel dielectrics. The model assumes that failure depends on the probability that an electron will have enough energy to damage the dielectric as it is accelerated in an electric field. It is seen that the characteristic form of the dependence of failure time on voltage or electric field is primarily dependent on the probability of having sufficient energy and not on the precise physical mechanism causing damage. An argument for a log-normal-like failure distribution is also presented.
Solid-phase epitaxial regrowth of amorphous layers in Si(100) created by low-energy, high-fluence phosphorus implantation
Authors: Ruffell S. , Mitchell I. V. , Simpson P. J.
Published: October 2005

Medium energy ion scattering has been used to study the kinetics of solid-phase epitaxial regrowth (SPEG) of ultrathin amorphous layers formed by room-temperature implantation of 5keV energy phosphorus ions into Si (100). The implants create P distributions with peak concentrations up to ∼7×1021cm−3. SPEG has been driven by rapid thermal annealing, 475°C⩽TA⩽600°C, for times up to 2000s. At each temperature, the regrowth velocity is enhanced in the early stages due to the presence of phosphorus but then slows sharply to a value more than an order of magnitude below the intrinsic rate. The critical phosphorus concentration at the transition point for TA=475°C regrowth is ∼6×1020cm−3 and increases steadily with anneal temperature. Time-of-flight secondary ion mass spectroscopy profiles confirm the onset of phosphorus push out, where the advancing recrystallization front enters the transition region. Supplementary cross-sectional transmission electron microscopy evidence confirms the existence of a local strain field.
Shallow water equations with a complete Coriolis force and topography
Authors: Dellar Paul J. , Salmon Rick
Published: October 2005

This paper derives a set of two-dimensional equations describing a thin inviscid fluid layer flowing over topography in a frame rotating about an arbitrary axis. These equations retain various terms involving the locally horizontal components of the angular velocity vector that are discarded in the usual shallow water equations. The obliquely rotating shallow water equations are derived both by averaging the three-dimensional equations and from an averaged Lagrangian describing columnar motion using Hamilton’s principle. They share the same conservation properties as the usual shallow water equations, for the same energy and modified forms of the momentum and potential vorticity. They may also be expressed in noncanonical Hamiltonian form using the usual shallow water Hamiltonian and Poisson bracket. The conserved potential vorticity takes the standard shallow water form, but with the vertical component of the rotation vector replaced by the component locally normal to the surface midway between the upper and lower boundaries.
Comparison of electrical properties of (100)∕(001)-oriented epitaxial Pb(Zr0.35,Ti0.65)O3 thin films with the same (001) domain fraction grown on (100)Si and (100)SrTiO3 substrates
Authors: Kim Yong Kwan , Morioka Hitoshi , Okamoto Shoji , Watanabe Takayuki , Yokoyama Shintaro , Sumi Akihiro , Funakubo Hiroshi , Saito Keisuke
Published: October 2005

Epitaxial tetragonal Pb(Zr0.35Ti0.65)O3 (PZT) films with a (100)∕(001) orientation and one and three in-plane variants were grown, respectively, on (100)cSrRuO3∕∕(100)SrTiO3 and (100)cSrRuO3∕∕(111)Pt∕∕(100)yttria stabilized zirconia (YSZ)∕∕(100)Si substrates by pulsed-metalorganic chemical vapor deposition, and their domain structure and electrical properties were investigated systematically. PZT films with the same volume fraction of c domains were grown on SrTiO3 and Si substrates by controlling the deposition temperature and film thickness. The relative dielectric constants at 1kHz were 370 and 450, respectively, for the films on the SrTiO3 and on the Si, even though both films had the same volume fractions, whereas the dielectric losses were almost the same. The remanent polarization and coercive field at the maximum applied electric field of 350kV∕cm were almost the same for both films, 30μC∕cm2 and 135kV∕cm, respectively. These results suggest that the key factor determining the ferroelectric property in epitaxial ferroelectric film is the relative volume fraction of c domains.
Moisture induced surface polarization in a poly(4-vinyl phenol) dielectric in an organic thin-film transistor
Authors: Jung Taeho , Dodabalapur Ananth , Wenz Robert , Mohapatra Siddharth
Published: October 2005

Surface polarization in a poly(4-vinyl phenol) (PVP) dielectric induced by water molecules has been qualitatively investigated in pentacene thin-film transistors. The magnitudes of drain currents from devices with PVP dielectrics subject to specific surface treatments increased with humidity, whereas the opposite responses were observed from device with SiO2 dielectrics. The increase in drain current is attributed to the accumulation of extra charge carriers induced by the surface polarization in addition to that by the vertical electric field. Such polarization effects should be carefully considered in characterizing organic and polymer thin-film transistors, particularly those with polymeric gate insulators.
Transition phenomena in a spherical Couette flow between independently rotating spheres
Authors: Nakabayashi Koichi , Tsuchida Yoichi
Published: October 2005

The quasistatic laminar-turbulent transition of spherical Couette flow between two independently rotating concentric spheres for a gap ratio (ratio of the gap between two spheres to the inner-sphere radius) of 0.14 for which the Taylor instability occurs in the case of the inner sphere rotating and the outer sphere fixed has been investigated by simultaneous spectral and flow-visualization measurements. Rotation frequencies (phase velocities), scaled by the mean rotation frequency of both spheres, of various periodic disturbances do not depend much on the ratio Ro*∕Ri* of the outer-sphere rotating Reynolds number Ro* to the inner-sphere rotating Reynolds number Ri*, although the phase velocity differs by the kind of disturbance. As disturbances unobserved in the case of the fixed outer sphere, traveling azimuthal waves only on an inflow boundary of toroidal Taylor-Görtler (TG) vortices and herringbone waves are observed in the case of co-rotating spheres, and spiral vortices and twists in toroidal TG vortices are observed in the case of counter-rotating spheres. Kinds and occurrence regions of flow regimes in the Ro*-Ri* plane considerably differ by the history of Ro* and Ri*.
High-bandwidth radio frequency Coulter counter
Authors: Wood D. K. , Oh S.-H. , Lee S.-H. , Soh H. T. , Cleland A. N.
Published: October 2005

We demonstrate a method for high-bandwidth, high-sensitivity particle sensing and cell counting in a microfluidic system. Our approach employs a tuned radiofrequency probe, which forms the radiofrequency analog of a Coulter counter. By measuring the reflected rf power, this approach provides an unprecedented detection rate, with a theoretical bandwidth in excess of 10 MHz. Particle detection was performed in a continuous flow mode in a microfluidic channel, using 15μm diameter polystyrene beads suspended in a sucrose-saline solution. We demonstrate 30 kHz counting rates and show high-resolution bead time-of-flight data, comprising the fastest electronic particle detection on-chip to date.
Heat capacity at the field-induced ferromagnetic transition in Eu0.58Sr0.42MnO3
Authors: Liu G. J. , Sun J. R. , Xie Y. W. , Wang D. J. , Xiong C. M. , Zhang H. W. , Zhao T. Y. , Shen B. G.
Published: October 2005

Eu 0.58 Sr 0.42 MnO 3 is found to own a wide variety of magnetic structures, and two subsequent magnetic transitions, a PM-AFM (paramagnetic-antiferromagnetic) transition followed by an AFM-FM (ferromagnetic) transition, are observed under proper magnetic field. It is found that the thermal response of heat capacity to the AFM-FM transition is negligibly small when this transition is well below the PM-AFM transition, and grows rapidly as the Curie temperature sweeps through the broad PM-AFM transition under the driving of magnetic field. This result indicates that the magnetic anomaly in heat capacity comes exclusively from the PM-FM transition, and the field-induced AFM-FM transition has essentially no thermal effects. A qualitative explanation for this result has been given based on the mean field theory.
Weakening of charge order and antiferromagnetic to ferromagnetic switch over in Pr0.5Ca0.5MnO3 nanowires
Authors: Rao S. S. , Anuradha K. N. , Sarangi S. , Bhat S. V.
Published: October 2005

We have prepared crystalline nanowires (diameter ∼50nm, length ∼a few microns) of the charge-ordering manganite Pr0.5Ca0.5MnO3 using a low reaction temperature hydrothermal method and characterized them using x-ray diffraction, transmission electron microscopy, superconducting quantum interference device (SQUID) magnetometry and electron magnetic resonance measurements. While the bulk sample shows a charge ordering transition at 245 K and an antiferromagnetic transition at 175 K, SQUID magnetometry and electron magnetic resonance experiments reveal that in the nanowires phase, a ferromagnetic transition occurs at ∼105K. Further, the antiferromagnetic transition disappears and the charge ordering transition is suppressed. This result is particularly significant since the charge order in Pr0.5Ca0.5MnO3 is known to be very robust, magnetic fields as high as 27 T being needed to melt it.
Complements to nonperturbative treatment of radiative damping effect in dielectronic recombination: Δn=2 transition in C IV
Authors: Stancalie V.
Published: October 2005

The primary purpose of the present work is to provide new refined results from nonperturbative treatment of the radiative damping effect in dielectronic recombination. The present results are used to test and confirm previously reported method [V. Stancalie, Phys. Plasmas 12, 043301 (2005)] taking full account of the electron collision and radiative processes in a consistent way, when radiation field is considered to all orders. This work refers to the 1s22s5s(S1) and 1s22p7s(P01) configurations, embedded in the electric dipole field of the 2s–2p core transition in Li-like C ion. Comparisons with previously reported results are shown. This data are believed to be the first demonstration of Δn=2 channel in dielectronic recombination of Li-like into Be-like C and are important in plasma diagnostics.
Technique to measure sub-microsecond magnetic field pulses using magnetic (CoPt) thin films
Authors: Syed W. , van Dover R. B. , Petrie J. R. , Mitchell M. D. , Hammer D. A.
Published: October 2005

We introduce a technique to measure the maximum magnetic field of a submicrosecond duration pulse using magnetic CoPt thin films. In the present experiment, this technique yields a lower limit for the field intensity and reveals the sense of that peak field. The time-varying magnetic field was generated by an exploding wire array plasma called an X pinch. Using a Quantum Design Superconducting Quantum Interference Device magnetometer, two thin films were initialized with remnant magnetization along a specific direction. The two films were then placed near an X-pinch plasma column with magnetizations in opposite directions. The current driven through the X pinch induced a change in magnetization in the films, which implied a lower bound of 17 kOe for the magnitude of the maximum magnetic field to which the film was exposed.
Growth of AlGaN nanowires by metalorganic chemical vapor deposition
Authors: Su J. , Gherasimova M. , Cui G. , Tsukamoto H. , Han J. , Onuma T. , Kurimoto M. , Chichibu S. F. , Broadbridge C. , He Y. , Nurmikko A. V.
Published: October 2005

Growth of ternary AlGaN nanowires using metalorganic chemical vapor deposition is investigated. Structural, chemical, and optical characterization at nanoscopic scale is carried out by high resolution transmission electron microscopy, x-ray energy dispersive spectroscopy, and spatially resolved cathodoluminescence. Spontaneous formation of Al(Ga)N∕GaN coaxial nanowires with distinct emission at 370 nm is observed. It is identified that the interplay between surface kinetics and thermodynamics facilitates the catalytic growth of GaN core while a limited surface diffusion of Al adatoms leads to nonselective, vapor-solid growth of Al(Ga)N sheath. The observation points to a fundamental difference in nanosynthesis using near-equilibrium and nonequilibrium techniques.
Radial ZnO nanowire nucleation on amorphous carbons
Authors: Yang Y. H. , Wang C. X. , Wang B. , Li Z. Y. , Chen J. , Chen D. H. , Xu N. S. , Yang G. W. , Xu J. B.
Published: October 2005

Radial ZnO nanowire arrays were self-assembled on the amorphous carbon thin layer on silicon substrates using thermal chemical vapor transport and condensation without any metal catalysts. We experimentally performed a systematic study to clarify the mechanism of the anomalous nucleation and growth and found that the physical origin of the nucleation aggregation and the one-dimensionally radial orientation is the immiscibility in the zinc oxide-carbon system.
Discovering inch-diameter metallic glasses in three-dimensional composition space
Authors: Ma H. , Shi L. L. , Xu J. , Li Y. , Ma E.
Published: October 2005

We have discovered low-cost bulk metallic glasses (BMGs) with diameters as large as 16to25mm based on the ordinary engineering metal Mg. We also use this example to present a new strategy, to illustrate how to navigate in three-dimensional composition space for locating the best glass-forming compositions. The extraordinary glass-forming ability demonstrated by the inch-sized BMGs has implications for future development and applications of amorphous metals.
Application of electrokinetic instability for enhanced mixing in various micro–T-channel geometries
Authors: Park Jaewan , Shin S. M. , Huh Kang Y. , Kang I. S.
Published: October 2005

We present simple effective micromixer designs utilizing electrokinetic instability (EKI) with downstream cavity structures in a micro-T channel. The amount of free charge increases at each corner of the cavities where inhomogeneous flow stream meets the electric field curved along the concentration gradient. The resulting Coulombic force enhances the instability and leads to a repetitive evolutionary flow pattern from one cavity to the next, yielding a higher mixing efficiency. The mixing efficiency is found to increase by about 15% for the channel with herringbone-shape cavities as compared with the straight channel.
Observation of TO1 soft mode in SrTiO3 films by terahertz time domain spectroscopy
Authors: Misra M. , Kotani K. , Kawayama I. , Murakami H. , Tonouchi M.
Published: October 2005

We have measured the dielectric properties of pulsed-laser-deposited SrTiO3 (STO) thin films by terahertz (THz) time-domain spectroscopy in the frequency range from 80GHzto1.5THz at temperatures from 20to290K. The measured frequency dispersion of the dielectric constant of the STO thin films show a clear Lorentzian oscillator behavior below 180K and softening of the ferroelectric soft mode of the STO thin films takes place with decreasing temperature. Both eigen frequency and damping of the soft phonon mode show a peak nearly at 110K that can be attributed to the effect on the Ti–O–Ti bending in STO thin film due to the starting of tilting in oxygen octahedra near the cubic to tetragonal phase transition. Dielectric strength saturates near the temperature 60K, however, that is a point of further investigation.
Relating random telegraph signal noise in metal-oxide-semiconductor transistors to interface trap energy distribution
Authors: van der Wel A. P. , Klumperink E. A. M. , Hoekstra E. , Nauta B.
Published: October 2005

In this work, we study random telegraph signal (RTS) noise in metal-oxide-semiconductor field effect transistors when the device is periodically and rapidly cycled between an “on” and an “off” bias state. We derive the effective RTS time constants for this case using Shockley–Read–Hall statistics applied under transient conditions. In this way, we show that the oft-observed reduction in RTS noise under such bias conditions can be explained by a nonuniform (e.g., U-shaped) distribution in energy of interface traps.
Deep-drainage control and yield: the trade-off between trees and crops in agroforestry systems in the medium to low rainfall areas of Australia
Authors: Oliver Y. M. , Lefroy E. C. , Stirzaker R. , Davies C. L.
Published: October 2005

In the dryland cropping areas of southern Australia, at risk from dryland salinity, tree belts can improve water management by taking up water unused by crops, with the risk that crop yield will be reduced through competition. As there are few direct markets for tree products grown in the medium to low rainfall areas, the design of agroforestry systems becomes important in reducing the trade-off in crop yield. This study examined some factors that influence the trade-off between crop yield and deep-drainage control in order to develop design guidelines for medium to low rainfall agroforestry. Twenty-one sites in the grain-growing region of Western Australia and southern New South Wales were surveyed over 2 years for crop yields, tree leaf area index, and estimated recharge, providing data from 32 tree–crop interfaces on the relative influence of environmental factors and farming system characteristics on the trade-off between water management and crop yield. The factors most strongly correlated with higher yields were water-gaining sites, orientation that provided shelter from southerly to north-westerly (S, SW, W, NW) winds, and tree age (<10 years). The factors most strongly correlated with the area of cropped land protected against deep drainage were tree age (>10 years), lighter soil types, and low rainfall (<400 mm). Economic analysis of the trade-off required to produce a particular deep-drainage reduction target produced 3 groups of sites: (1) those where trees resulted in a gross margin increase of $15/ha and an estimated deep-drainage reduction of 52% (n = 3), (2) those with a gross margin loss of $49/ha and estimated deep-drainage reduction of 47% (n = 11), and (3) those with a gross margin loss of $163/ha and a deep-drainage reduction of 37% (n = 18). None of the 3 sites in the first group were in the most favourable class in both years, highlighting the vulnerability of a relatively fixed farming system to climate variability.
The phosphorus and nitrogen requirements of temperate pasture species and their influence on grassland botanical composition
Authors: Hill J. O. , Simpson R. J. , Wood J. T. , Moore A. D. , Chapman D. F.
Published: October 2005

Grassland production in southern Australia is generally based on phosphorus (P)- and nitrogen (N)-deficient soils. Use of P-fertiliser is necessary for high production in higher rainfall zones and economic pressures are increasing the need to apply fertiliser more widely and consistently. The P and N requirements of 10 temperate pasture species were examined to understand how increased fertiliser use will affect grassland botanical composition. The plant species fell into 2 main groups with respect to their critical external P requirements (P application rates required to achieve 90% of maximum yield) : those with a high requirement (Trifolium subterraneum, Hordeum leporinum, Bromus molliformis, Microlaena stipoides, and Phalaris aquatica), and those with a low requirement (Lolium rigidum, Vulpia spp., Austrodanthonia richardsonii, and Holcus lanatus). The critical external N requirements of H. leporinum, L. rigidum, and B. molliformis were significantly higher than those of A. richardsonii, Arctotheca calendula, and H. lanatus. Species that ‘tolerate’ nutrient stress were relatively abundant in unfertilised grazing systems and tall ‘competitor’ species were dominant in fertilised pasture under low grazing pressure. The abundance of the species present in fertilised pastures grazed for high utilisation was negatively correlated with their relative growth rates and it is hypothesised that this may indicate that abundance was determined by tolerance or avoidance of grazing.
The use of canola oil coatings to extend the storage life of Nashi pears
Authors: Szczerbanik M. J. , Scott K. J. , Paton J. E. , Best D. J.
Published: October 2005

Nashi cv. Nijisseiki was coated with canola oil before storage at 0°C over 3 consecutive seasons. This resulted in greater retention of green colour, even after only 8 weeks of storage. This effect continued throughout the 40-week storage period and after 1 week at 20°C. Physiological disorders were generally low. The internal atmosphere was measured during storage at 0°C. The mean carbon dioxide levels for control and treated fruit were approximately 0.5 and 1.9%, and oxygen levels were 20 and 13%, respectively. The mean ethylene levels were approximately 5 and 30 μL/L, respectively. Thus, in oiled fruit, increased carbon dioxide levels may have overcome the effects of increased levels of ethylene. When fruit was transferred to 20°C, carbon dioxide and ethylene levels rose and oxygen levels fell but no damage was evident at the lower oil concentrations. Non-oiled fruit was then stored in polyethylene bags with or without a carbon dioxide absorbent (Calcium hydroxide) and an ethylene absorbent (Purafil). Fruit stored with the former became as yellow as the control fruit in air, whilst fruit with Purafil remained greener than fruit held in bags alone. When the absorbents were used together, much of the fruits’ green colour was lost. Carbon dioxide levels therefore appear to be most important for the retention of green colour, and generally improve storage life. Ethylene removal further improves the retention of green colour in the Nijisseiki cultivar. A storage life of at least 40 weeks at 0°C was achieved with fruit from several sources in 3 seasons. Preliminary recommendations for small-scale hand applications are 1 or 2 drops per 240 g fruit. Commercial trials could involve dipping or spraying with 1–2% oil emulsified with Tween 80.
Quantitative trait loci for root lesion nematode (Pratylenchus thornei) resistance in Middle-Eastern landraces and their potential for introgression into Australian bread wheat
Authors: Schmidt A. L. , McIntyre C. L. , Thompson J. , Seymour N. P. , Liu C. J.
Published: October 2005

Plant parasitic nematodes are a major biotic cause of wheat yield loss in temperate wheat-growing regions. Previous studies using Australian germplasm and/or synthetic hexaploid lines have identified quantitative trait loci (QTLs) for root lesion nematode resistance on chromosomes 2B, 6D, and 7A. This study examines Pratylenchus thornei resistance in 2 Middle-Eastern landraces (AUS13124 and AUS4926), using doubled haploid populations generated by crossing with the susceptible Australian cultivar Janz. Single marker regression and QTL analysis identified resistance loci on chromosomes 2B, 3B, 6D, and 7A, and a susceptibility locus on chromosome 1B. The 2B and 6D loci, which have been reported to explain up to 19% and 24% of variation, respectively, in previous studies, made smaller contributions in the Middle-Eastern varieties, explaining 2–13% (2B) and 1–6% (6D) of phenotypic variation in these populations. The previously reported 7A locus (P. neglectus resistance) was detected through single marker regression only (AUS13124 × Janz – LRS = 4.1, P = 0.04292; AUS4926 × Janz – LRS = 9.6, P = 0.00195), with genotype at the microsatellite marker Xgwm350.3 accounting for 3–23% of phenotypic variation. The previously unreported resistance QTL, located on chromosome 3B, explained up to 24% of phenotypic variation, and the susceptibility locus on chromosome 1B explained up to 21%. The 3B locus was detected in both the AUS13124 × Janz (max. LRS = 20.13) and AUS4926 × Janz (max. LRS = 11.19) populations, and the 1B locus was detected in the AUS4926 × Janz population (max. LRS = 18.82) only.
Backcross reciprocal monosomic analysis of leaf relative water content, stomatal resistance, and carbon isotope discrimination in wheat under pre-anthesis water-stress conditions
Authors: Mohammady-D Shahram , Moore Keith , Ollerenshaw John , Shiran Behrooz
Published: October 2005

Monosomic plants from an Australian variety (Oxley) having low stomatal resistance (SR), low leaf relative water content (LRWC), and high carbon isotope discrimination (Δ) were crossed with variety Falchetto having opposite characters in order to produce F2 backcross reciprocal monosomic families. The families were assessed under pre-anthesis water-stress conditions in a controlled growth chamber. F2 backcross reciprocal monosomic analysis suggested possible allelic variations between chromosomes 1A, 3A, 6A, 7A, 7B, 1D, and 4D of Falchetto and their homologues in Oxley for LRWC. This analysis also suggested possible allelic variation between chromosomes 5A, 1A, and 3A of Falchetto and their homologues in Oxley for SR. Extending the analysis to the F3 disomic generation and the assessment of LRWC at this generation confirmed that reciprocals for chromosomes 3A and 6A showed significant differences. F2 backcross reciprocal monosomic analysis for Δ suggested allelic variations on chromosomes 1D, 4D, and 5D. However, chromosome 1D from Falchetto had the highest difference from its homologue in Oxley. Assessing the reciprocals of this chromosome for vegetative evapotranspiration efficiency (ETEveg) at the F3 disomic generation indicated that the observed variation for Δ was translated into differences for ETEveg. These results indicate that chromosome 1D of Falchetto is promising in reducing Δ and that the improvement of wheat varieties for ETEveg can be done by selection for Δ. Finally, plieotropic effects of some chromosomes were observed for the characters under study. This suggests the existence of genetic factors on these chromosomes affecting more than one character. However, some pleiotropic effects could also be due to non-genetic developmental interactions.
Phosphorus uptake by grain legumes and subsequently grown wheat at different levels of residual phosphorus fertiliser
Authors: Nuruzzaman M. , Lambers Hans , Bolland Michael D. A. , Veneklaas Erik J.
Published: October 2005

A considerable portion of the phosphorus (P) fertilisers applied in agriculture remains in the soil as sorbed P in the forms of various P compounds, termed residual P. Certain grain legume crops may be able to mobilise residual P through root exudates, and thus increase their own growth, and potentially that of subsequent cereal crops. The first objective of this pot experiment was to compare the growth and P uptake of 3 legume crop species with that of wheat grown in a soil with different levels of residual P. Another objective was to determine whether the influence of legumes on subsequent P uptake by wheat was due to legume-induced changes in the rhizosphere, or to the presence of legume roots. White lupin (Lupinus albus L.), field pea (Pisum sativum L.), faba bean (Vicia faba L.), and wheat (Triticum aestivum L.) were grown in a soil containing 25.7, 26.4, 30.8, 39.0, or 51.9 mg/kg of bicarbonate-extractable P and sufficient amounts of nitrogen to suppress nodulation and dinitrogen fixation. Differences among the species in root dry mass were much larger than those in shoot dry mass. Faba bean produced the greatest root dry mass. All the legumes exuded carboxylates from their roots, predominantly malate, at all soil P levels. Rhizosphere concentrations of carboxylates were highest for white lupin, followed by field pea and faba bean. All of the investigated legumes enhanced the growth of the subsequently grown wheat, compared with wheat grown after wheat, even at relatively high levels of soil P. The positive effect on growth was not dependent on the incorporation of the legume roots into the soil. The legumes also caused a modest increase in wheat shoot P concentrations, which were higher when roots were incorporated into the soil. Because of the increased growth and tissue P concentrations, wheat shoot P content was 30–50% higher when grown after legumes than when grown after wheat. The study concludes that the legume crops can enhance P uptake of subsequently grown wheat, even at relatively high levels of residual P.
A newly identified type of scrapie agent can naturally infect sheep with resistant PrP genotypes
Authors: Le Dur Annick , Béringue Vincent , Andréoletti Olivier , Reine Fabienne , Laï Thanh Lan , Baron Thierry , Bratberg Bjørn , Vilotte Jean-Luc , Sarradin Pierre , Benestad Sylvie L. , Laude Hubert
Published: October 2005

Scrapie in small ruminants belongs to transmissible spongiform encephalopathies (TSEs), or prion diseases, a family of fatal neurodegenerative disorders that affect humans and animals and can transmit within and between species by ingestion or inoculation. Conversion of the host-encoded prion protein (PrP), normal cellular PrP (PrP
c
), into a misfolded form, abnormal PrP (PrP
Sc
), plays a key role in TSE transmission and pathogenesis. The intensified surveillance of scrapie in the European Union, together with the improvement of PrP
Sc
detection techniques, has led to the discovery of a growing number of so-called atypical scrapie cases. These include clinical Nor98 cases first identified in Norwegian sheep on the basis of unusual pathological and PrP
Sc
molecular features and “cases” that produced discordant responses in the rapid tests currently applied to the large-scale random screening of slaughtered or fallen animals. Worryingly, a substantial proportion of such cases involved sheep with PrP genotypes known until now to confer natural resistance to conventional scrapie. Here we report that both Nor98 and discordant cases, including three sheep homozygous for the resistant PrP
ARR
allele (A
136
R
154
R
171
), efficiently transmitted the disease to transgenic mice expressing ovine PrP, and that they shared unique biological and biochemical features upon propagation in mice. These observations support the view that a truly infectious TSE agent, unrecognized until recently, infects sheep and goat flocks and may have important implications in terms of scrapie control and public health.
Synergy between interstitial flow and VEGF directs capillary morphogenesisin vitrothrough a gradient amplification mechanism
Authors: Helm Cara-Lynn E. , Fleury Mark E. , Zisch Andreas H. , Boschetti Federica , Swartz Melody A.
Published: October 2005

Cell organization is largely orchestrated by extracellular gradients of morphogenetic proteins. VEGF, an essential factor for capillary formation, is stored in the extracellular matrix, but the mechanisms by which it and other matrix-bound morphogens are mobilized to form spatial gradients are poorly understood. Here, we suggest an efficient mechanism for morphogen gradient generation by subtle biophysical forces in anin vitromodel of capillary morphogenesis. Using a fibrin-bound VEGF variant that is released proteolytically to mimic thein vivosituation, we report that low levels of interstitial flow act synergistically with VEGF to drive endothelial organization, whereas each stimulus alone has very little effect. To help account for this synergy, we show how these slow flows can bias the distribution of cell-secreted proteases, which leads, interestingly, to the creation of an increasing VEGF gradient relative to the cell and skewed in the direction of flow. In contrast, diffusion alone can only account for symmetric, decreasing autocrine gradients. Indeed, branching of capillary structures was biased in the direction of flow only with the combination of VEGF and flow. This work thus demonstrates a general mechanism of morphogen gradient generation and amplification by small ubiquitous mechanical forces that are known to existin vivo.
Distinctions in the specificity of E2F function revealed by gene expression signatures
Authors: Black Esther P. , Hallstrom Timothy , Dressman Holly K. , West Mike , Nevins Joseph R.
Published: October 2005

The E2F family of transcription factors provides essential activities for coordinating the control of cellular proliferation and cell fate. Both E2F1 and E2F3 proteins have been shown to be particularly important for cell proliferation, whereas the E2F1 protein has the capacity to promote apoptosis. To explore the basis for this specificity of function, we used DNA microarray analysis to probe for the distinctions in the two E2F activities. Gene expression profiles that distinguish either E2F1- or E2F3-expressing cells from quiescent cells are enriched in genes encoding cell cycle and DNA replication activities, consistent with many past studies. E2F1 profile is also enriched in genes known to function in apoptosis. We also identified patterns of gene expression that specifically differentiate the activity of E2F1 and E2F3; this profile is enriched in genes known to function in mitosis. The specificity of E2F function has been attributed to protein interactions mediated by the marked box domain, and we now show that chimeric E2F proteins generate expression signatures that reflect the origin of the marked box, thus linking the biochemical mechanism for specificity of function with specificity of gene activation.