bluuebunny/crossref_metadata_2025 huggingface dataset:
High-resolution rotational spectroscopy of the carbon chain anions C3N−, C4H−, and C4D−
Authors: McCarthy M. C. , Thaddeus P.
Published: August 2008

The rotational spectra of C3N−, C4H−, and C4D− have been measured at high-spectral resolution by Fourier transform microwave spectroscopy. For both C3N− and C4D−, hyperfine structure in the lowest-J transitions has been resolved and measured to better than 0.1ppm. The quadrupole coupling constants eQq for both anions are close to those of the neutral counterparts C3N and C4D, and that of C3N− is in good agreement with theoretical calculations. Several properties of these anions, including their linewidths, drift velocities, and abundances, are systematically compared to similar-sized neutral molecules. The production of C4H− with different hydrocarbon precursor and buffer gases is also discussed.
Origins of ferromagnetism in transition-metal doped Si
Authors: Ko V. , Teo K. L. , Liew T. , Chong T. C. , MacKenzie M. , MacLaren I , Chapman J. N.
Published: August 2008

We present results of the magnetic, structural, and chemical characterizations of Mn+-implanted Si displaying n-type semiconducting behavior and ferromagnetic ordering with Curie temperature, TC, well above room temperature. The temperature-dependent magnetization measured by superconducting quantum interference device from 5 to 800 K was characterized by three different critical temperatures (TC*∼45 K, TC1∼630–650 K, and TC2∼805–825 K). Their origins were investigated using dynamic secondary ion mass spectroscopy and transmission electron microscopy (TEM) techniques, including electron energy loss spectroscopy, Z-contrast scanning TEM imaging, and electron diffraction. We provided direct evidences of the presence of a small amount of Fe and Cr impurities which were unintentionally doped into the samples together with the Mn+ ions as well as the formation of Mn-rich precipitates embedded in a Mn-poor matrix. The observed TC* is attributed to the Mn4Si7 precipitates identified by electron diffraction. Possible origins of TC1 and TC2 are also discussed. Our findings raise questions regarding the origin of the high-TC ferromagnetism reported in many material systems without a careful chemical analysis.
Fundamental aspects of concentration polarization arising from nonuniform electrokinetic transport
Authors: Khair Aditya S. , Squires Todd M.
Published: August 2008

Recent experiments have demonstrated that large-scale ion concentration gradients, or “concentration polarization,” can be generated from perm-selective transport through nanochannels or nonuniform surface conduction around polarizable electrodes. The theoretical modeling of concentration polarization phenomena is, however, a daunting task: for example, an analysis of the above mentioned systems requires the treatment of a set of highly coupled, nonlinear partial differential equations for the ion concentrations, electric field, and fluid flow. In this paper, we present and analyze a model system that simply and clearly highlights a variety of fundamental aspects of concentration polarization. Specifically, we consider a binary symmetric electrolyte overlying a flat wall, whose surface charge varies periodically. An electric field applied parallel to the wall causes nonuniform ionic transport within the thin diffuse layer adjacent to the wall. In turn, this nonuniform transport drives gradients in the bulk ion, or salt, concentration and electric field. Notably, the bulk variations persist over the macroscopic length scale L of the surface charge variation rather than the microscopic (Debye length λD) thickness of the diffuse layer. We formalize these ideas by deriving effective boundary conditions coupling the diffuse-layer transport to the bulk electrolyte dynamics. In the limit of a weak applied field and small surface charge density (the Debye–Huckel limit), the electrolyte response is investigated for three prototypical cases: (i) a steady (dc) field, (ii) a suddenly applied field, and (iii) an oscillatory (ac) field. In particular, for a steady field we examine the interplay of diffusion and advection in shaping the bulk concentration polarization zones.
Molecular dynamics simulations of near-surface modification of polystyrene: Bombardment with Ar+ and Ar+/radical chemistries
Authors: Végh J. J. , Nest D. , Graves D. B. , Bruce R. , Engelmann S. , Kwon T. , Phaneuf R. J. , Oehrlein G. S. , Long B. K. , Willson C. G.
Published: August 2008

Molecular dynamics (MD) simulations have been carried out to examine the effects of Ar+, Ar+/H, and Ar+/F bombardment of a model polystyrene (PS) surface. For bombardment with 100 eV Ar+ only, the simulations show the formation of a heavily cross-linked dehydrogenated damaged layer in the near-surface region after some initial fluence, consistent with plasma and beam system experimental results. The 1–2 nm thick amorphous carbon-rich modified layer has a much lower sputter yield compared to that of the virgin PS, which has a H:C ratio of 1. Simultaneous bombardment of the damaged dehydrogenated PS layer with 300 K H or F radicals and 100 eV Ar+ can facilitate the removal of the layer as well as inhibit its initial formation. The development of the steady-state dehydrogenated layer under Ar+-only bombardment results from a competition between the breaking of carbon-hydrogen bonds (which leads to dehydrogenation and subsequent cross-linking) and the breaking of carbon-carbon bonds (which leads to sputtering of polymer fragments). For the conditions presented in this study, the loss of hydrogen eventually overtakes the removal of polymer fragments, resulting in the formation of the dehydrogenated cross-linked near-surface layer. The final properties of the dehydrogenated layer from the MD simulations are compared at steady state to ellipsometric data for plasma-exposed PS samples, and the initial and final sputter yields from MD are compared to experimental beam system data.
High pressure torsion of amorphous Cu60Zr30Ti10 alloy
Authors: Hóbor Sándor , Révész Ádám , Szabó Péter J. , Zhilyaev Alex P. , Kis Viktória Kovács , Lábár János L. , Kovács Zsolt
Published: August 2008

High pressure torsion was applied to produce a disk-shaped specimen of Cu60Zr30Ti10 composition. The dependence of the morphology, microstructure, and thermal behavior on the applied shear strain was monitored by scanning and transmission electron microscopies, synchrotron x-ray diffraction, and calorimetry. The disk consists of a gradient microstructure ranging from large homogeneous blocks (about 20 μm) to finely dispersed nanocrystals (about 20 nm) of two stable hexagonal phases and continuously decreasing amorphous content with increasing strain. The evolution of such microstructure was interpreted by using a model based on heat conduction generated by the extensive shear deformation.
X-ray spectropolarimeter
Authors: Baronova E. O. , Stepanenko M. M. , Stepanenko A. M.
Published: August 2008

We have constructed a novel single-crystal x-ray spectropolarimeter that separates spatially the two perpendicularly polarized components of an x-ray beam. We have tested this device by using an x-ray tube, and confirmed its performance to be satisfactory as expected from its design.
Light amplification by stimulated Raman scattering in AlGaAs-based photonic-crystal line-defect waveguides
Authors: Oda Hisaya , Inoue Kuon , Yamanaka Akio , Ikeda Naoki , Sugimoto Yoshimasa , Asakawa Kiyoshi
Published: August 2008

The authors performed an amplification experiment of optical signal around 1550 nm by stimulated Raman scattering in a photonic-crystal slab waveguide (WG) of single-line defect. They adopted an air-bridge type AlGaAs-based WG sample to avoid two-photon absorption. Short light pulses of 5 ps in duration operated at 20 MHz and a cw laser were employed for pump (excitation) and probe (signal) lights, respectively. As a result, amplification of a net gain of ∼3 dB (maximum) is achieved with pulse pump energy of 22 pJ for a sample of 1.0 mm in length.
Linear and nonlinear ion-acoustic waves in very dense magnetized plasmas
Authors: Khan S. A. , Mahmood S. , Saleem H.
Published: August 2008

Obliquely propagating linear and weakly nonlinear ion-acoustic waves in a magnetized quantum plasma are investigated by employing the quantum hydrodynamic formulation. A linear dispersion relation is presented and the nonlinear Korteweg–de Vries equation is derived using the reductive perturbative method. The dispersion caused by the quantum diffraction effects is possible only in a very short wavelength regime. The amplitude and width of the solitons formed by the ion-acoustic waves propagating in a magnetized plasma depend upon various parameters. Possible applications of the results to dense plasmas are discussed.
Multifractal and statistical analyses of heat release fluctuations in a spark ignition engine
Authors: Sen Asok K. , Litak Grzegorz , Kaminski Tomasz , Wendeker Mirosław
Published: August 2008

Using multifractal and statistical analyses, we have investigated the complex dynamics of cycle-to-cycle heat release variations in a spark ignition engine. Three different values of the spark advance angle (Δβ) are examined. The multifractal complexity is characterized by the singularity spectrum of the heat release time series in terms of the Hölder exponent. The broadness of the singularity spectrum gives a measure of the degree of mutifractality or complexity of the time series. The broader the spectrum, the richer and more complex is the structure with a higher degree of multifractality. Using this broadness measure, the complexity in heat release variations is compared for the three spark advance angles (SAAs). Our results reveal that the heat release data are most complex for Δβ=30° followed in order by Δβ=15° and 5°. In other words, the complexity increases with increasing SAA. In addition, we found that for all the SAAs considered, the heat release fluctuations behave like an antipersistent or a negatively correlated process, becoming more antipersistent with decreasing SAA. We have also performed a statistical analysis of the heat release variations by calculating the kurtosis of their probability density functions (pdfs). It is found that for the smallest SAA considered, Δβ=5°, the pdf is nearly Gaussian with a kurtosis of 3.42. As the value of the SAA increases, the pdf deviates from a Gaussian distribution and tends to be more peaked with larger values of kurtosis. In particular, the kurtosis has values of 3.94 and 6.69, for Δβ=15° and 30°, respectively. A non-Gaussian density function with kurtosis in excess of 3 is indicative of intermittency. A larger value of kurtosis implies a higher degree of intermittency.
Indicators of internal structural states for metallic glasses: Local order, free volume, and configurational potential energy
Authors: Cheng Y. Q. , Ma E.
Published: August 2008

The structural states of metallic glasses (MGs) have been described previously using concepts such as free volume and configurational potential energy. Here we discuss the inadequacy of these indicators by examining a Cu–Zr–Al MG model experiencing different cooling and relaxation history. The results identify the local (icosahedral) ordering as a fundamental process underlying structural relaxation, and the degree of order as a more sensitive and revealing structural indicator.
Liquid crystal optical phase plate with a variable in-plane gradient
Authors: Shi Lei , McManamon Paul F. , Bos Philip J.
Published: August 2008

We propose a nematic liquid crystal (LC) optical phase plate, with a large continuous in-plane gradient that is variable, and its application to a beam steering device with high efficiency. The device is a vertically aligned, continuous phase, optical phased array (V-COPA) that uses a negative dielectric anisotropy LC material. High steering efficiency of over 95% is demonstrated by modeling the LC director field and its effect on transmitted light. The period of the V-COPA grating can be varied by adjusting an applied voltage profile, which allows for continuous angular control of the diffraction angle.
Full-wave analysis of extraordinary backscattering by a layered plasmonic nanosphere
Authors: Geng You-Lin , Qiu Cheng-Wei , Zouhdi Saïd
Published: August 2008

An exact full-wave analysis of plane-wave scattering by a multilayer nanosphere is proposed. The code is then used to study the behavior of N-layered plasmonic spherical particles. Our primary interest lies in achieving extraordinary scattering or transparency in the infrared regime by judicious pairing of plasmonic materials and control of the core-shell ratio. Numerical results and physical insights of these extraordinary phenomena are provided.
Tuning the coercivity of Fe-filled carbon-nanotube arrays by changing the shape anisotropy of the encapsulated Fe nanoparticles
Authors: Shi C. X. , Cong H. T.
Published: August 2008

To tune the coercivity of Fe-filled carbon-nanotube (CNT) arrays, the shape anisotropy of encapsulated Fe nanoparticles (Fe-NPs) was investigated. Four Fe-filled CNT-array samples with different Fe-NP aspect ratios were prepared by catalytic pyrolysis of acetylene using ferrocene as catalyst. The coercivity of the Fe-filled CNT arrays increased from ∼300 to ∼800 Oe at room temperature when the mean aspect ratio of the encapsulated Fe-NPs changed from 1.6 to 6.0. This clear dependence of the coercivity of the Fe-filled CNT arrays on the aspect ratio of the Fe-NPs might be interpreted in terms of the Stoner–Wohlfarth model. This result indicates that changing the shape anisotropy of the encapsulated Fe-NPs is an effective method to tune the coercivity of the Fe-filled CNTs.
Field-induced soft mode hardening in SrTiO3/DyScO3 multilayers
Authors: Kužel P. , Kadlec C. , Kadlec F. , Schubert J. , Panaitov G.
Published: August 2008

We investigate a SrTiO3/DyScO3 epitaxial multilayer with four 50-nm-thick layers of each compound deposited on DyScO3 substrate by pulsed laser deposition. The spectra of SrTiO3 obtained using time-domain terahertz spectroscopy at room temperature with and without electrical bias are explained by the ferroelectric soft mode coupled to a silent central peak, where the bare soft mode frequency is the only field-dependent parameter. We show that terahertz and subterahertz properties of the layers are determined solely by a tremendous hardening of the soft mode with increasing field. We demonstrate that our structure induces more than 40% modulation of the transmitted terahertz power in a broad frequency range of 0.65–1.15 THz at 140 V (93 kV/cm) bias.
Ultrasensitive low noise voltage amplifier for spectral analysis
Authors: Giusi G. , Crupi F. , Pace C.
Published: August 2008

Recently we have proposed several voltage noise measurement methods that allow, at least in principle, the complete elimination of the noise introduced by the measurement amplifier. The most severe drawback of these methods is that they require a multistep measurement procedure. Since environmental conditions may change in the different measurement steps, the final result could be affected by these changes. This problem is solved by the one-step voltage noise measurement methodology based on a novel amplifier topology proposed in this paper. Circuit implementations for the amplifier building blocks based on operational amplifiers are critically discussed. The proposed approach is validated through measurements performed on a prototype circuit.
Development and research of a coaxial microwave plasma thruster
Authors: Yang Juan , Xu Yingqiao , Tang Jinlan , Mao Genwang , Yang Tielian , Tan Xiaoquen
Published: August 2008

An overview of the research on a coaxial microwave plasma thruster at Northwestern Polytechnic University is presented. Emphasis is put on the development and research on key components of the thruster system, a microthrust balance, plasma plume diagnostics, and a numerical simulation of the plasma flow field inside the thruster cavity. The developed thruster cavity is chosen from a coaxial resonant cavity with concentrated capacitance, which can operate well in atmosphere and vacuum conditions. The development of a microwave source shows that a magnetron powered by a switch power supply has advantages in the power level and efficiency, but a solid state microwave source synthesized from the arsenide field effect transistor is superior in weight and volume. Through elimination of the effect of large gravity and resistance force induced by a gas pipe line and a microwave transmitting line on the microthrust, 15mN and 340s in the performance of the microwave plasma thruster at 70W and with helium gas are measured. Diagnosing experiment shows that the plasma plume density is in the range of (1–7.2)×1016∕m3. Numerical simulation of the plasma flow field inside the coaxial thruster cavity shows that there is a good match between the microwave power and gas flow rate.
Radio-frequency power assistance on a compact magnetohydrodynamic electrical power generator under high-density magnetic flux
Authors: Murakami Tomoyuki , Okuno Yoshihiro
Published: August 2008

We describe the effect of radio-frequency (rf) electromagnetic field application on a compact magnetohydrodynamic (MHD) electrical power generator under high-density magnetic flux. The rf-power assistance improves the Hall potential profile and fluid flow structure, and rectifies large-scale plasma instability. These effects are vital for the compact MHD generator. With the aid of rf power, the power generation performance is significantly improved even under the low-plasma-stability condition for high-density magnetic flux.
Band alignment and thermal stability of HfO2 gate dielectric on SiC
Authors: Chen Q. , Feng Y. P. , Chai J. W. , Zhang Z. , Pan J. S. , Wang S. J.
Published: August 2008

The band alignment and thermal stability for HfO2 films on SiC with and without nitridation have been studied by using photoemission spectroscopy. The valence- and conduction-band offsets at HfO2/4H-SiC interfaces were measured to be 1.02 and 1.53 eV, respectively. The atomic source nitridation improves interface thermal stability with nitrogen passivation for the oxygen vacancies in dielectric films and for the defects on SiC surface, but induces band gap reduction for the HfO2 dielectric layer and band alignment shift at the interface. Postnitridation annealing helps to improve the band offsets of dielectric film to have sufficient injection barrier.
Electron mobility in phosphorous doped {111} homoepitaxial diamond
Authors: Pernot J. , Koizumi S.
Published: August 2008

The room temperature Hall electron mobility of phosphorous doped {111} homoepitaxial diamond is investigated experimentally and described theoretically for different doping and compensating center densities. The impurities mobility dependence is established. The mobility is found to be controlled by the lattice scattering mechanisms in low doped material (below 1017 cm−3), by lattice and ionized impurity scattering for moderate doping level (1017 cm−3<ND<1018 cm−3), and by neutral impurity scattering for highly doped material (above 1018 cm−3). The mobility parameters required to simulate the electric characteristics of electronic devices between 300 and 500 K in a wide doping range are then determined.
Inversion-channel GaN metal-oxide-semiconductor field-effect transistor with atomic-layer-deposited Al2O3 as gate dielectric
Authors: Chang Y. C. , Chang W. H. , Chiu H. C. , Tung L. T. , Lee C. H. , Shiu K. H. , Hong M. , Kwo J. , Hong J. M. , Tsai C. C.
Published: August 2008

Inversion n-channel GaN metal-oxide-semiconductor field-effect-transistors (MOSFETs) using atomic-layer-deposited Al2O3 as a gate dielectric have been fabricated, showing well-behaved drain I-V characteristics. The drain current was scaled with gate length (varying from 1to16μm), showing a maximum drain current of ∼10mA∕mm in a device of 1μm gate length, at a gate voltage of 8V and a drain voltage of 10V. At a drain voltage of 0.1V, a high Ion∕Ioff ratio of 2.5×105 was achieved with a very low off-state leakage of 4×10−13A∕μm. Both MOSFET and MOS capacitor showed very low leakage current densities of 10−8A∕cm2 at biasing fields of 4MV∕cm. The interfacial density of states was calculated to be (4–9)×1011cm−2eV−1 near the midgap.
Atmospheric pressure nitrogen plasma jet: Observation of striated multilayer discharge patterns
Authors: Hong Yong Cheol , Uhm Han Sup , Yi Won Ju
Published: August 2008

This paper presents a nitrogen microplasma jet that operates at atmospheric pressure and provides details of an observation of the striated multilayer discharge patterns formed in the plasma jet. The plasma jet device in a microhollow electrode is a pencil-type configuration that produces a long cold plasma jet capable of reaching 3.5cm and having various excited plasma species shown through optical emission spectrum. By introducing a gas flow rate of more than 5l∕min, striated discharge patterns in the plasma jet are produced through ionization wave propagation.
Characterization of laser-transferred bismuth ferrite lead titanate ferroelectric thick films
Authors: Comyn Tim P. , Chakraborty Tanusri , Miles Robert E. , Milne Steven J.
Published: August 2008

Thick films of 0.7BiFeO3–0.3PbTiO3 have been deposited on sapphire substrates by tape casting and sintering at 1000°C. Films 20μm in thickness were released from the fabrication substrate using KrF pulsed laser radiation, and epoxy bonded to platinized silicon substrates in order to demonstrate the low-temperature integration possibilities of xBiFeO3–(1−x)PbTiO3 films. Despite structural changes at the laser-released film interface, strain-electric field loops are typical of a ferroelectric, showing an ultimate strain of 0.09%. X-ray diffraction and scanning electron microscopy observations suggest that interfacial melting and migration of Bi2O3 is involved in the lift-off process.
High-density horizontally aligned growth of carbon nanotubes with Co nanoparticles deposited by arc-discharge plasma method
Authors: Phokharatkul D. , Ohno Y. , Nakano H. , Kishimoto S. , Mizutani T.
Published: August 2008

High-density horizontally aligned single-walled carbon nanotubes are grown on a quartz substrate using Co nanoparticles deposited by arc-discharge plasma method. The Co nanoparticles with a density as high as 6.0×1010cm−2 are formed by a single pulse of arc discharge at room temperature. The density of the aligned nanotubes is ∼8μm−1 in average. Multichannel nanotube field-effect transistors with a high-k top-gate structure are fabricated with aligned nanotubes. The devices show high-performance, normally on, and n-type conduction property without any doping process. A high on current of 1.3mA and a large transconductance of 0.23mS for a channel width of 100μm are obtained. The normally on and n-type property is attributed to fixed positive charges in the HfO2 gate insulator and at the interfaces.
Titanium dioxide nanofiber-cotton targets for efficient multi-keV x-ray generation
Authors: Tanabe Minoru , Nishimura Hiroaki , Fujioka Shinsuke , Nagai Keiji , Yamamoto Norimasa , Gu Zhong-Ze , Pan Chao , Girard Frederic , Primout Michel , Villette Bruno , Brebion Didier , Fournier Kevin B. , Fujishima Akira , Mima Kunioki
Published: August 2008

Multi-keV x-ray generation from low-density (27±7mg∕cm3) nanofiber-cotton targets composed of titanium dioxide has been investigated. The cotton targets were heated volumetrically and supersonically to a peak electron temperature of 2.3keV, which is optimal to yield Ti K-shell x rays. Considerable enhancement of conversion efficiency [(3.7±0.5)%] from incident laser energy into Ti K-shell x rays (4–6keV band) was attained in comparison with that [(1.4±0.9)%] for a planar Ti-foil target.
Genetic resistance to growth of Lucilia cuprina larvae in Merino sheep
Authors: Smith J. L. , Colditz I. G. , Piper L. R. , Sandeman R. M. , Dominik S.
Published: August 2008

Cutaneous myiasis (fly strike), caused by Lucilia cuprina, is a major ectoparasitic infection of sheep. Previous research has identified contributions of body conformation, wool characteristics and resistance to bacterial dermatoses to resistance to fly strike. This paper investigates whether genetic variation occurs amongst sheep in growth of larvae on skin. Mixed sex Merino sheep in 27 half-sibling groups were challenged with freshly hatched Lucilia cuprina larvae, and survival and growth of larvae were measured after 50 h. Growth but not survival of larvae had moderate heritability (0.29 ± 0.22), comparable to that seen for resistance to nematode parasites in sheep. Phenotypic correlations between resistance to larval growth and wool traits, skin wheal response to intradermal injection of larval excretory secretory products and resistance to internal parasites were negligible; however, there was a significant negative phenotypic correlation with fleece rot score after exposure of sheep to simulated rain at a time independent to that of measurement of larval growth. Larval growth was negatively correlated with peripheral blood eosinophil numbers measured either before or after larval challenge. In addition, larval growth in vitro on serum collected from challenged sheep was moderately associated with larval growth in vivo. A search for quantitative trait loci (QTL) for larval survival and growth was conducted in data from 94 half-sibling progeny of a Merino × Romney sire backcrossed to Merino ewes. Potential QTL for larval growth were identified on chromosome 11 and for larval survival on chromosome 18, although phenotyping greater numbers of sheep and a higher marker density on these chromosomes is necessary to confirm the result. We conclude that this study has identified a novel level of resistance of Merino sheep to growth of L. cuprina larvae that may be mediated in part through actions of anti-larval factors in serum and eosinophils. Further studies are required to establish the impact of growth retardation on the severity of systemic responses of sheep to fly strike and on the biology of adult flies.
Using automated supplementation systems to meet growth targets for grazing sheep
Authors: Bowen M. K. , Pepper P. M. , Winkleman J. L. , McPhie R. C. , Winter M. R.
Published: August 2008

Remote drafting technology now available for sheep allows targeted supplementation of individuals within a grazing flock. This paper reports results of three experiments. Experiment 1 examined the weight change of Merino wethers allowed access to either lupin grain or whole cottonseed 0, 1, 2 or 7 days/week for 6 weeks. Experiment 2 examined the weight change of Merino wethers allowed access to either lupins or a sorghum + cottonseed meal (CSM) supplement 0, 2, 4 or 7 days/week for 8 weeks. Experiment 3 investigated the relationship between five allocations of trough space at the supplement self-feeders (5–50 cm/sheep) and the weight change of Merino wethers allowed access to lupins 1 day/week for 8 weeks. In all experiments, the Merino wethers had free access as a single group to drinking water and low quality hay in a large group pen and were allowed access to supplement once per day on their scheduled days of access. No water was available in the areas containing supplement, but one-way flow gates allowed animals to return to the group pen in their own time.
There was a linear response in growth rate to increased frequency of access to lupins in Experiments 1 and 2, with each additional day of access increasing liveweight gain by 26 and 21 g/day, respectively. Similarly, the response to the sorghum + CSM supplement was linear, although significantly lower (P < 0.05), at 12 g/day. Providing access to whole cottonseed resulted in no significant change in growth rate compared with the control animals. In Experiment 3, decreasing trough space from 50 to 5 cm/sheep had no effect on sheep liveweight change.
It was concluded that the relationships developed here, for growth response to increased frequency of access to lupins or a sorghum + CSM supplement, could be used to indicate the most appropriate frequency of access to supplement, through a remote drafting unit, to achieve sheep weight change targets. Also, that a trough space of 5 cm/sheep appears adequate in this supplementation system.
Effects of sodium chloride and betaine on hydration status of lambs at slaughter
Authors: Pearce K. L. , Masters D. G. , Jacob R. H. , Hopkins D. L. , Pethick D. W.
Published: August 2008

Under commercial conditions in Australia, lambs are often dehydrated at slaughter despite access to water at the abattoir. Dehydration results in reduced fluid content of meat, which causes liveweight and carcass weight loss. Two experiments evaluated hydration status and carcass characteristics in lambs fed increased levels of sodium chloride (salt) and/or betaine before slaughter. Both experiments were 2 × 2 factorial designs with two levels of salt added [0 and 50 g/kg dry matter (DM)] and two levels of betaine added (0 and 6.7 g/kg DM) to the diets. The treatment diets were introduced to sheep over a 7–8-day period and then fed at 1.5 kg/day for the following 7 days. In experiment 1, 96 Poll Dorset–Merino cross wether lambs (45.9 ± 0.17 kg) were fed in individual pens and in experiment 2, 204 Merino wether lambs (43.1 ± 0.35 kg) were fed in group pens. In the first experiment, water and feed were withheld from the end of the treatment feeding period until slaughter 48 h later. In the second experiment, feed and water were withheld for the first 24 h after treatment but water was available for the next 24 h immediately before slaughter. In both experiments, consumption of the high salt diet decreased urine specific gravity and osmolarity at the end of the feeding period and after 24 h without access to water. This indicates an improved hydration status at this time. However, the difference in hydration status related to feeding salt declined during the 48-h lairage period and there were no significant differences in hot carcass weight or muscle DM among groups at slaughter. It could be concluded from this result that the addition of salt has little commercial value; however, this may not be the case. The lambs in experiment 2 did not behave according to industry expectations. They all drank water in the last 24 h in lairage and none of the groups showed severe dehydration. Further research is justified to determine if the lambs fed the diets with no added salt drunk in lairage as a learned response from the lambs fed salt and, if so, whether this can be developed into a commercial strategy. Feeding betaine did not result in any changes in hydration status or carcass characteristics.
Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 1. Description of traits, model comparison, variance components and their ratios
Authors: Huisman A. E. , Brown D. J. , Ball A. J. , Graser H.-U.
Published: August 2008

Both wool and sheep meat industries are interested in sheep that have a high reproduction performance and are resistant to internal parasites, in addition to the traditional traits. There is considerable interest in breeding sheep for wool, carcass, reproductive and internal parasite resistance traits simultaneously. The objective of this study was to estimate single trait genetic parameters for 40 traits recorded in Merino sheep, covering bodyweight, carcass, wool, reproduction and internal parasite resistance traits. This also involved determining the appropriate models. The results from this study will be used to review the genetic parameters used in the routine genetic evaluations conducted by Sheep Genetics. The most appropriate models included a maternal genetic effect and covariance between direct and maternal genetic effects for most of the bodyweight traits, greasy and clean fleece weight, fibre diameter and coefficient of variation of fibre diameter. The permanent environment due to the dam was not included for any trait. There was considerable genetic variation in most traits analysed; lowest heritabilities (0.09–0.10) were found for number of lambs born and weaned per lambing opportunity, and highest heritabilities (0.62–0.77) for fibre diameter. The estimated heritabilities and genetic variances, in combination with the estimated correlations, indicate that there is potential to make genetic improvement in most traits currently recorded in Australian Merino sheep.
Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 2. Genetic relationships between bodyweight traits and other traits
Authors: Huisman A. E. , Brown D. J.
Published: August 2008

The Australian Merino is the predominant genetic resource for both the prime lamb and sheep meat industries of Australia. There are very few studies that provide good information on the relationships between wool and non-wool traits. The objective of this paper was to describe genetic relationships within bodyweight traits and between bodyweight and other traits recorded in Merino sheep. The genetic correlation between bodyweight, fleece weight and fibre diameter was positive (0.1 to 0.2). While fibre diameter coefficient of variation, staple length, staple strength, mean fibre curvature, and faecal egg count were not correlated with bodyweight. Scrotal circumference (0.4), number of lambs born (0.1), and number of lambs weaned (0.1) were positively correlated with bodyweight. Results indicate that selection for an increase in bodyweight will have a positive effect on eye muscle depth, fleece weight, and reproduction traits, while selection for an increase in bodyweight will have a negative effect on fibre diameter and fibre diameter coefficient of variation.
Warming of the Indian Ocean threatens eastern and southern African food security but could be mitigated by agricultural development
Authors: Funk Chris , Dettinger Michael D. , Michaelsen Joel C. , Verdin James P. , Brown Molly E. , Barlow Mathew , Hoell Andrew
Published: August 2008

Since 1980, the number of undernourished people in eastern and southern Africa has more than doubled. Rural development stalled and rural poverty expanded during the 1990s. Population growth remains very high, and declining per-capita agricultural capacity retards progress toward Millennium Development goals. Analyses of
in situ
station data and satellite observations of precipitation have identified another problematic trend: main growing-season rainfall receipts have diminished by ≈15% in food-insecure countries clustered along the western rim of the Indian Ocean. Occurring during the main growing seasons in poor countries dependent on rain-fed agriculture, these declines are societally dangerous. Will they persist or intensify? Tracing moisture deficits upstream to an anthropogenically warming Indian Ocean leads us to conclude that further rainfall declines are likely. We present analyses suggesting that warming in the central Indian Ocean disrupts onshore moisture transports, reducing continental rainfall. Thus, late 20th-century anthropogenic Indian Ocean warming has probably already produced societally dangerous climate change by creating drought and social disruption in some of the world's most fragile food economies. We quantify the potential impacts of the observed precipitation and agricultural capacity trends by modeling “millions of undernourished people” as a function of rainfall, population, cultivated area, seed, and fertilizer use. Persistence of current tendencies may result in a 50% increase in undernourished people by 2030. On the other hand, modest increases in per-capita agricultural productivity could more than offset the observed precipitation declines. Investing in agricultural development can help mitigate climate change while decreasing rural poverty and vulnerability.
Nitric oxide promotes distant organ protection: Evidence for an endocrine role of nitric oxide
Authors: Elrod John W. , Calvert John W. , Gundewar Susheel , Bryan Nathan S. , Lefer David J.
Published: August 2008

Endothelial NOS (eNOS)-derived NO has long been considered a paracrine signaling molecule only capable of affecting nearby cells because of its short half-life in blood and relatively limited diffusion distance in tissues. To date, no studies have demonstrated that endogenously generated NO possesses a clearly defined endocrine function. Therefore, we evaluated whether enzymatic generation of NO in the heart is capable of modulating remote physiological actions and cell signaling. Mice with cardiac-specific overexpression of the human eNOS gene (CS-eNOS-Tg) were used to address this hypothesis. Cardiac-specific eNOS overexpression resulted in significant increases in nitrite, nitrate, and nitrosothiols in the heart, plasma, and liver. To examine whether the increase in hepatic NO metabolites could modulate cytoprotection, we subjected CS-eNOS-Tg mice to hepatic ischemia-reperfusion (I/R) injury. CS-eNOS-Tg mice displayed a significant reduction in hepatic I/R injury (4.2-fold reduction in the aminotransferase and a 3.5-fold reduction in aspartate aminotransferase) compared with WT littermates. These findings demonstrate that endogenously derived NO is transported in the blood, metabolized in remote organs, and mediates cytoprotection in the setting of I/R injury. This study presents clear evidence for an endocrine role of NO generated endogenously from eNOS and provides additional evidence for the profound cytoprotective actions of NO in the setting of I/R injury.
Tumor-derived endothelial cells exhibit aberrant Rho-mediated mechanosensing and abnormal angiogenesis
in vitro
Authors: Ghosh Kaustabh , Thodeti Charles K. , Dudley Andrew C. , Mammoto Akiko , Klagsbrun Michael , Ingber Donald E.
Published: August 2008

Tumor blood vessels exhibit abnormal structure and function that cause disturbed blood flow and high interstitial pressure, which impair delivery of anti-cancer agents. Past efforts to normalize the tumor vasculature have focused on inhibition of soluble angiogenic factors, such as VEGF; however, capillary endothelial (CE) cell growth and differentiation during angiogenesis are also influenced by mechanical forces conveyed by the extracellular matrix (ECM). Here, we explored the possibility that tumor CE cells form abnormal vessels because they lose their ability to sense and respond to these physical cues. These studies reveal that, in contrast to normal CE cells, tumor-derived CE cells fail to reorient their actin cytoskeleton when exposed to uniaxial cyclic strain, exhibit distinct shape sensitivity to variations in ECM elasticity, exert greater traction force, and display an enhanced ability to retract flexible ECM substrates and reorganize into tubular networks
in vitro
. These behaviors correlate with a constitutively high level of baseline activity of the small GTPase Rho and its downstream effector, Rho-associated kinase (ROCK). Moreover, decreasing Rho-mediated tension by using the ROCK inhibitor, Y27632, can reprogram the tumor CE cells so that they normalize their reorientation response to uniaxial cyclic strain and their ability to form tubular networks on ECM gels. Abnormal Rho-mediated sensing of mechanical cues in the tumor microenvironment may therefore contribute to the aberrant behaviors of tumor CE cells that result in the development of structural abnormalities in the cancer microvasculature.
Combination therapy of established cancer using a histone deacetylase inhibitor and a TRAIL receptor agonist
Authors: Frew Ailsa J. , Lindemann Ralph K. , Martin Ben P. , Clarke Christopher J. P. , Sharkey Janelle , Anthony Desiree A. , Banks Kellie-Marie , Haynes Nicole M. , Gangatirkar Pradnya , Stanley Kym , Bolden Jessica E. , Takeda Kazuyoshi , Yagita Hideo , Secrist J. Paul , Smyth Mark J. , Johnstone Ricky W.
Published: August 2008

Histone deacetylase inhibitors (HDACi) and agents such as recombinant tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and agonistic anti-TRAIL receptor (TRAIL-R) antibodies are anticancer agents that have shown promise in preclinical settings and in early phase clinical trials as monotherapies. Although HDACi and activators of the TRAIL pathway have different molecular targets and mechanisms of action, they share the ability to induce tumor cell-selective apoptosis. The ability of HDACi to induce expression of TRAIL-R death receptors 4 and 5 (DR4/DR5), and induce tumor cell death via the intrinsic apoptotic pathway provides a molecular rationale to combine these agents with activators of the TRAIL pathway that activate the alternative (death receptor) apoptotic pathway. Herein, we demonstrate that the HDACi vorinostat synergizes with the mouse DR5-specific monoclonal antibody MD5-1 to induce rapid and robust tumor cell apoptosis
in vitro
and
in vivo
. Importantly, using a preclinical mouse breast cancer model, we show that the combination of vorinostat and MD5-1 is safe and induces regression of established tumors, whereas single agent treatment had little or no effect. Functional analyses revealed that rather than mediating enhanced tumor cell apoptosis via the simultaneous activation of the intrinsic and extrinsic apoptotic pathways, vorinostat augmented MD5-1-induced apoptosis concomitant with down-regulation of the intracellular apoptosis inhibitor cellular-FLIP (c-FLIP). These data demonstrate that combination therapies involving HDACi and activators of the TRAIL pathway can be efficacious for the treatment of cancer in experimental mouse models.
Conserved residues modulate copper release in human copper chaperone Atox1
Authors: Hussain Faiza , Olson John S. , Wittung-Stafshede Pernilla
Published: August 2008

It is unclear how the human copper (Cu) chaperone Atox1 delivers Cu to metal-binding domains of Wilson and Menkes disease proteins in the cytoplasm. To begin to address this problem, we have characterized Cu(I) release from wild-type Atox1 and two point mutants (Met
10
Ala and Lys
60
Ala). The dynamics of Cu(I) displacement from holo-Atox1 were measured by using the Cu(I) chelator bicinchonic acid (BCA) as a metal acceptor. BCA removes Cu(I) from Atox1 in a three-step process involving the bimolecular formation of an initial Atox1–Cu–BCA complex followed by dissociation of Atox1 and the binding of a second BCA to generate apo-Atox1 and Cu–BCA
2
. Both mutants lose Cu(I) more readily than wild-type Atox1 because of more rapid and facile displacement of the protein from the Atox1–Cu–BCA intermediate by the second BCA. Remarkably, Cu(I) uptake from solution by BCA is much slower than the transfer from holo-Atox1, presumably because of slow dissociation of DTT–Cu complexes. These results suggest that Cu chaperones play a key role in making Cu(I) rapidly accessible to substrates and that the activated protein–metal–chelator complex may kinetically mimic the ternary chaperone–metal–target complex involved in Cu(I) transfer
in vivo
.
Excessive genomic DNA copy number variation in the Li–Fraumeni cancer predisposition syndrome
Authors: Shlien Adam , Tabori Uri , Marshall Christian R. , Pienkowska Malgorzata , Feuk Lars , Novokmet Ana , Nanda Sonia , Druker Harriet , Scherer Stephen W. , Malkin David
Published: August 2008

DNA copy number variations (CNVs) are a significant and ubiquitous source of inherited human genetic variation. However, the importance of CNVs to cancer susceptibility and tumor progression has not yet been explored. Li–Fraumeni syndrome (LFS) is an autosomal dominantly inherited disorder characterized by a strikingly increased risk of early-onset breast cancer, sarcomas, brain tumors and other neoplasms in individuals harboring germline
TP53
mutations. Known genetic determinants of LFS do not fully explain the variable clinical phenotype in affected family members. As part of a wider study of CNVs and cancer, we conducted a genome-wide profile of germline CNVs in LFS families. Here, by examining DNA from a large healthy population and an LFS cohort using high-density oligonucleotide arrays, we show that the number of CNVs per genome is well conserved in the healthy population, but strikingly enriched in these cancer-prone individuals. We found a highly significant increase in CNVs among carriers of germline
TP53
mutations with a familial cancer history. Furthermore, we identified a remarkable number of genomic regions in which known cancer-related genes coincide with CNVs, in both LFS families and healthy individuals. Germline CNVs may provide a foundation that enables the more dramatic chromosomal changes characteristic of TP53-related tumors to be established. Our results suggest that screening families predisposed to cancer for CNVs may identify individuals with an abnormally high number of these events.
Single molecule force spectroscopy reveals engineered metal chelation is a general approach to enhance mechanical stability of proteins
Authors: Cao Yi , Yoo Teri , Li Hongbin
Published: August 2008

Significant mechanical stability is an essential feature shared by many elastomeric proteins, which function as molecular springs in a wide variety of biological machinery and biomaterials of superb mechanical properties. Despite the progress in understanding molecular determinants of mechanical stability, it remains challenging to rationally enhance the mechanical stability of proteins. Using single molecule force spectroscopy and protein engineering techniques, we demonstrate that engineered bi-histidine metal chelation can enhance the mechanical stability of proteins significantly and reversibly. Based on simple thermodynamic cycle analysis, we engineered a bi-histidine metal chelation site into various locations of the small protein, GB1, to achieve preferential stabilization of the native state over the mechanical unfolding transition state of GB1 through the binding of metal ions. Our results demonstrate that the metal chelation can enhance the mechanical stability of GB1 by as much as 100 pN. Since bi-histidine metal chelation sites can be easily implemented, engineered metal chelation provides a general methodology to enhance the mechanical stability of a wide variety of proteins. This general approach in protein mechanics will enable the rational tuning of the mechanical stability of proteins. It will not only open new avenues toward engineering proteins of tailored nanomechanical properties, but also provide new approaches to systematically map the mechanical unfolding pathway of proteins.
Immunochemical termination of self-tolerance
Authors: Grünewald Jan , Tsao Meng-Lin , Perera Roshan , Dong Liqun , Niessen Frank , Wen Ben G. , Kubitz Diane M. , Smider Vaughn V. , Ruf Wolfram , Nasoff Marc , Lerner Richard A. , Schultz Peter G.
Published: August 2008

The ability to selectively induce a strong immune response against self-proteins, or increase the immunogenicity of specific epitopes in foreign antigens, would have a significant impact on the production of vaccines for cancer, protein-misfolding diseases, and infectious diseases. Here, we show that site-specific incorporation of an immunogenic unnatural amino acid into a protein of interest produces high-titer antibodies that cross-react with WT protein. Specifically, mutation of a single tyrosine residue (Tyr86) of murine tumor necrosis factor-α (mTNF-α) top-nitrophenylalanine (pNO2Phe) induced a high-titer antibody response in mice, whereas no significant antibody response was observed for a Tyr86→ Phe mutant. The antibodies generated against the pNO2Phe are highly cross-reactive with native mTNF-α and protect mice against lipopolysaccharide (LPS)-induced death. This approach may provide a general method for inducing an antibody response to specific epitopes of self- and foreign antigens that lead to a neutralizing immune response.