bluuebunny/crossref_metadata_2025 huggingface dataset:
Rate constants and branching ratios for the dissociative recombination of CO2+
Authors: Viggiano A. A. , Ehlerding A. , Hellberg F. , Thomas R. D. , Zhaunerchyk V. , Geppert W. D. , Montaigne H. , Larsson M. , Kaminska M. , Österdahl F.
Published: June 2005

Product branching ratios and thermal rate coefficients for the dissociative recombination of CO2+ have been measured in the cryogenic ion source ring ion storage ring. The rate constants were found to be 4.2×10−7(Te∕300)−0.75cm3s−1. The 300-K result is in agreement with previous flowing afterglow values and is somewhat smaller than a recent determination made at the Aarhas storage ring in Denmark (ASTRID) storage ring. The electron temperature dependence is, however, in good agreement with the ASTRID result of T−0.8. The present results show that only CO plus O are formed, other product branching ratios are zero within experimental error. This is in contradiction to the ASTRID results which show that 9% of the reactivity goes to C+O2. The new results show that the C+O2 channel does not need to be included in the models of the ionospheres of Venus and Mars.
Equilibrium positions, shape invariance and Askey–Wilson polynomials
Authors: Odake Satoru , Sasaki Ryu
Published: June 2005

We show that the equilibrium positions of the Ruijsenaars–Schneider–van Diejen systems with the trigonometric potential are given by the zeros of the Askey–Wilson polynomials with five parameters. The corresponding single particle quantum version, which is a typical example of “discrete” quantum mechanical systems with a q-shift type kinetic term, is shape invariant and the eigenfunctions are the Askey–Wilson polynomials. This is an extension of our previous study, which established the “discrete analogue” of the well-known fact; the equilibrium positions of the Calogero systems are described by the Hermite and Laguerre polynomials, whereas the corresponding single particle quantum versions are shape invariant and the eigenfunctions are the Hermite and Laguerre polynomials.
Unimolecular dissociation and thermochemistry of CH3OOH
Authors: Matthews Jamie , Sinha Amitabha , Francisco Joseph S.
Published: June 2005

The unimolecular dissociation of CH3OOH is investigated by exciting the molecule in the region of its 5νOH band and probing the resulting OH fragments using laser-induced fluorescence. The measured OH fragment rotational and translational energies are used to determine the CH3O–OH bond dissociation energy, which we estimate to be ∼42.6±1kcal∕mol. Combining this value with the known heats of formation of the fragments also gives an estimate for the heat of formation of CH3OOH which at 0K we determine to be ΔHf0=−27±1kcal∕mol. This experimental value is in good agreement with the results of ab initio calculations carried out at the CCSD(T)/complete basis set limit which finds the heat of formation of CH3OOH at 0K to be ΔHf0=−27.3kcal∕mol.
Nonholonomic versus vakonomic dynamics on a Riemann–Cartan manifold
Authors: Guo Yong-Xin , Wang Yong , Chee G. Y. , Mei Feng-Xiang
Published: June 2005

For the Chaplygin’s nonholonomic constrained systems, the constraint manifold can be endowed with Riemann–Cartan geometric structure by nonholonomic mapping into a Riemann manifold. The two kinds of existing dynamics, nonholonomic dynamics and vakonomic dynamics, are compared in the framework of Riemann–Cartan geometry. It is proved that the equations of motion for nonholonomic and vakonomic dynamics are described by the equations of autoparallel and geodesic trajectories on the Riemann–Cartan constraint manifold, respectively. If the metricity condition of Riemann–Cartan connection is satisfied, the torsion (contorsion) of the Riemann–Cartan manifold characterizes the difference between the autoparallel and geodesic trajectories as well as the distinction between the nonholonomic and vakonomic equations.
Nonlinear dynamic of low-frequency Buneman instability of a current-driven plasma
Authors: Shokri B. , Niknam A. R.
Published: June 2005

Theoretical investigation of the nonlinear dynamic of the low-frequency Buneman instability of a current-driven plasma is presented. In the nonlinear stage, this instability is described by the diffusion equation with a negative nonlinear diffusion coefficient. As a result, the plasma density profile reaches a sharp peak and is accompanied by the breakdown of quasineutrality and establishment of stationary self-focusing structures.
Kinetic Alfvén waves in plasmas with heavy ions
Authors: Yang L. , Wu D. J.
Published: June 2005

Since its wide identification in measurements by satellites in space plasmas as well as its potential importance in the energization of plasma particles, the kinetic Alfvén wave (KAW) has been discussed extensively in the two-component (electron-proton) plasma model. The component of heavy ions, however, can frequently be found in space and astrophysical plasmas and can affect considerably the properties of the KAWs in them. In this paper, based on a three-component (i.e., electrons, protons, and heavy ions) plasma model, characteristics of KAWs are investigated. The results show that the dispersion of KAWs splits up into two branches. In the long wavelength limit, one branch has an asymptotic solution of shear Alfvén waves, while the other approaches an electrostatic wave with a frequency between the proton and heavy ion gyrofrequencies. Their polarization and resonance are also discussed.
Stochastic acceleration in peaked spectrum
Authors: Zasenko V. , Zagorodny A. , Weiland J.
Published: June 2005

Diffusion in velocity space of test particles undergoing external random electric fields with spectra varying from low intensive and broad to high intensive and narrow (peaked) is considered. It is shown that to achieve consistency between simulation and prediction of the microscopic model, which is reduced to Fokker–Planck-type equation, it is necessary, in the case of peaked spectrum, to account for temporal variation of diffusion coefficient occurring in the early stage. An analytical approximation for the solution of the Fokker–Planck equation with a time and velocity dependent diffusion coefficients is proposed.
Polarization evolution of radiation in hot magnetized plasma with dissipation
Authors: Segre S. E. , Zanza V.
Published: June 2005

A formalism is presented for the analysis of polarization evolution in a magnetized plasma with dissipation due to kinetic effects. Such a plasma in addition to the Faraday and Cotton-Mouton effects also presents dichroism, namely anisotropic absorption. As expected this effect is significant near the cyclotron harmonics.
Radiative centers in GaS doped with Zn and Cd
Authors: Shigetomi S. , Ikari T.
Published: June 2005

Photoluminescence (PL) measurement has been made on Zn- and Cd-doped p-GaS. The 1.85 and 1.95eV emission bands are observed in the PL spectra of Zn- and Cd-doped samples at 77K, respectively. The shapes of PL spectrum and temperature dependences of full width at half maximum of the 1.85 and 1.95eV emission bands are characterized by the recombination mechanism of the configurational coordinate model. It is found that these emission bands are related to the complex centers of vacancy and acceptors due to Zn or Cd atoms.
Plasma density gradient measurement using laser deflection
Authors: Brockington Samuel J. E. , Horton Robert D. , Hwang David Q. , Evans Russell W. , Howard Stephen J. , Thio Y. C. Francis
Published: June 2005

For a given chord through a plasma, changes in the line integrated index of refraction as a result of a transverse density gradient can be observed by measuring the angle of deflection of a laser beam. In contrast to laser interferometers, this method of density profile measurement places modest requirements on laser quality and alignment procedures, allowing measurements to be conducted with short coherence length commercial laser diodes and segmented photodiode detectors. A prototype implementation of this scheme has been constructed and tested on the compact toroid injection experiment (CTIX). At densities comparable to magnetic fusion plasmas, laser deflections in the nanoradian range were measured. By assuming a particular density profile, a sensitivity of ∼1012cm−3∕nrad was obtained. This produced estimates of CTIX peak density in reasonable agreement with conventional interferometry data. The final goal of this diagnostic is a simple, reliable, array deployable density profile diagnostic.
Variational principle with singular perturbation of hall magnetohydrodynamics
Authors: Ohsaki Shuichi , Yoshida Zensho
Published: June 2005

The Hall magnetohydrodynamics (H-MHD) model can describe an intrinsic small scale (ion skin depth ℓi) introduced by the Hall effect. The Hall term appears as a singular perturbation to the conventional magnetohydrodynamics (MHD) model, and hence, the MHD limit (ℓi→0) may be singular. The H-MHD system has three constants of motion, the energy, the magnetic (electron) and ion helicities. The ion helicity is known to be “fragile” with respect to the energy norm of the magnetic and flow fields [Z. Yoshida and S. M. Mahajan, Phys. Rev. Lett. 88, 095001 (2002)]. Under an appropriate ordering of scales, the ion helicity translates as the cross helicity that is a constant of motion of the MHD system. Conservation of the cross helicity is an essential condition to recover the macroscopic MHD picture from the H-MHD framework.
Studies of a low-impedance coaxial split-cavity oscillator
Authors: Yang Wenyuan , Ding Wu
Published: June 2005

A low-impedance coaxial split-cavity oscillator (SCO) for high output power is proposed and studied by simulation in this paper. By using the coaxial structure, the space-charge limiting current can be improved markedly, and thus more intense electron beams can be used for microwave generation. Compared with the conventional SCO, the modulation and extraction cavities are combined into one split cavity with an output window, whose quality factor Q is very low. And the cavity length of each section is not equal. Simulations have verified that the output power is high at medium beam voltage, the time for saturation is relatively short (about 12ns), and the efficiency stays at almost the same level as a conventional SCO. By using an annular electron beam of 400kV and 25kA, the rms efficiency can reach 19% at an output power of 1.9GW at 1.235GHz. Simulations also show that the efficiency is insensitive to the beam power and the operating frequency is determined mainly by the structure parameters.
Control of the charge and the nonlinear oscillation of dust particles by alternating current voltage superposition on the cathode in a direct current discharge
Authors: Park S. , Seon C. R. , Choe W.
Published: June 2005

Experimental and theoretical studies were conducted to investigate the control of charge and modification of nonlinear oscillations of externally injected dust particles in a dc discharge. The superposition of ac voltage on a dc cathode led to plasma density modulation, which brought about a drastic change of particle oscillation characteristics. Examples of the changes include disappearance of the subharmonic resonance peak and hysteresis as the ac superposition voltage was increased, which is attributed to the fact that the ac superposition made sheath structure less nonlinear and less parametrically resonant. In addition, as the ac frequency decreased from 5kHzto1kHz at the same ac voltage (15V), the subharmonic peak became weakened along with its frequency. This result demonstrates that the dust charge is the main parameter in determining occurrence of the subharmonic resonance peak. We consequently expect that modification of the oscillation dynamics of dust particles and furthermore the separate control of the charge may be possible by the ac modulation of the dc biased cathode.
Shear flow reduction by the geodesic transfer mechanism in tokamak edge turbulence
Authors: Kendl A. , Scott B. D.
Published: June 2005

The geodesic transfer mechanism in tokamak edge plasmas, which serves as an important saturation mechanism for the self-generation of zonal flows by E-cross-B turbulence, is analyzed and quantified. Modification of the geodesic curvature is shown to influence the transport reduction by self-consistent sheared zonal flows. Specifically, the shear flows are enhanced for a scaling similar to the effect of increasing elongation and safety factor.
An impulsive bathtub vortex
Authors: Tyvand Peder A. , Haugen Kjetil B.
Published: June 2005

The impulsive free-surface flow due to a point sink at the bottom of a container with rotating inviscid fluid is investigated analytically by a small-time expansion. Before the sink is turned on impulsively, there is a steady rigid-body rotation with large Rossby number (small angular velocity). The theory is developed to first order in the inverse Rossby number. The evolution of the free-surface vorticity is investigated. The azimuthal surface velocity is a cubic function of time. It is shown that the influence of the rotation of the earth on an impulsive bathtub vortex is negligible.
Instruments for preparation of heterogeneous catalysts by an impregnation method
Authors: Yamada Yusuke , Akita Tomoki , Ueda Atsushi , Shioyama Hiroshi , Kobayashi Tetsuhiko
Published: June 2005

Instruments for the preparation of heterogeneous catalysts in powder form have been developed. The instruments consist of powder dispensing robot and an automated liquid handling machine equipped with an ultrasonic and a vortex mixer. The combination of these two instruments achieves the catalyst preparation by incipient wetness and ion exchange methods. The catalyst library prepared with these instruments were tested for dimethyl ether steam reforming and characterized by transmission electron microscopy observations.
Energy nonequipartition, rheology, and microstructure in sheared bidisperse granular mixtures
Authors: Alam Meheboob , Luding Stefan
Published: June 2005

Event-driven simulations of smooth inelastic hard disks are used to probe the transport properties and the microstructure of bidisperse granular mixtures. A generic feature of such mixtures is that the two species have different levels of fluctuation kinetic energy (Tl≠Ts) in contrast with their elastic counterpart. The microscopic mechanism for this energy nonequipartition is shown to be directly tied to the asymmetric nature of collisional probabilities between the heavier and lighter species, compared to their purely elastic counterpart. The degree of collisional asymmetry increases with both increasing inelasticity and mass disparity, thereby increasing the energy ratio Tl∕Ts in the same limit. A phenomenological constitutive model, that incorporates energy nonequipartition, captures the nonmonotonic behavior of the transport coefficients, in agreement with the simulation results, whereas the standard constitutive model with equipartition assumption predicts monotonic variations. The sheared granular mixture readily forms clusters, having striped patterns along the extensional axis of the flow. The microstructural flow features are extracted by measuring the cluster-size distributions, the pair-correlation function and the collision-angle distribution. While the inelastic dissipation is responsible for the onset of clustering, we have found that the mass disparity between the two species enhances the degree of clustering significantly in the sense that the size of the largest cluster increases with increasing mass disparity. At the microscopic level, the particle motion becomes more and more streamlined (i.e., ordered along the streamwise direction which is also a signature of enhanced short-range correlations) with increasing dissipation and mass disparity, which is responsible for the enhanced first normal stress difference in the same limit.
Magnetization force sensor
Authors: Maki Syou , Ataka Mitsuo
Published: June 2005

Magnetization force acting on nonmagnetic materials has found wide uses as one of the applications that can be realized by a superconducting magnet. We propose a sensor that can measure the magnetization force three-dimensionally at a time. It consists of 24 Hall-effect magnetic sensors to define all the components of magnetic gradients needed to calculate the magnetization force. The correctness of the principle was examined by making a prototype with eight Hall-effect sensors. The influence of the off-center displacement was also confirmed.
Temperature sensitivity of a long-period waveguide grating in a channel waveguide
Authors: Liu Qing , Chiang K. S. , Lor K. P. , Chow C. K.
Published: June 2005

We present a simulation of the temperature sensitivity of the resonance wavelength of a long-period waveguide grating (LPWG). We find that the temperature sensitivity of an LPWG in a channel waveguide is proportional to a modal dispersion factor that depends sensitively on the size of the core of the waveguide. Measurements with experimental polymer LPWGs agree well with the simulation results. The dimension of the waveguide core is an effective parameter for the control of the thermal characteristics of an LPWG in a channel waveguide.
Patterning of confined-state energies in site-controlled semiconductor quantum dots
Authors: Watanabe S. , Pelucchi E. , Leifer K. , Malko A. , Dwir B. , Kapon E.
Published: June 2005

We demonstrate control of the confined-state energies of semiconductor quantum dots (QDs) grown on prepatterned substrates. The InGaAs∕AlGaAs QDs self-order at the apex of self-limiting, inverted pyramids whose locations are fixed by lithography. The confinement energy in the dots is systematically varied across the substrate by changing the pattern of the pyramid array in their vicinity. The resulting energy- and site-controlled QDs show systematic and reproducible shifts of their emission wavelengths as well as antibunched photon emissions from confined single excitons. Such QDs should be useful for applications in quantum information processing and quantum communication devices, e.g., multiple-wavelength single-photon emitters.
Rechargeable hydrogen storage in nanostructured mixtures of hydrogenated carbon and lithium hydride
Authors: Ichikawa Takayuki , Fujii Hironobu , Isobe Shigehito , Nabeta Koji
Published: June 2005

A hydrogen storage ability caused by the interaction between nanostructured carbon (CnanoHx) and lithium hydride (LiH) is demonstrated, which should be recognized as Li-C-H system in the H-storage materials. Especially, the 2:1 mixture of CnanoHx and LiH exhibited promising hydrogen storage properties with a rechargeable hydrogen capacity of more than 4 mass% below 350 °C, preserving the nanostructural feature in the mixture even after hydrogen release. On the other hand, the 1:2 and 1:1 mixtures exhibited the crystal growth of Li2C2 after hydrogen desorption, leading to poorer hydrogen rechargeability.
Detection and identification of explosives using terahertz pulsed spectroscopic imaging
Authors: Shen Y. C. , Lo T. , Taday P. F. , Cole B. E. , Tribe W. R. , Kemp M. C.
Published: June 2005

The absorption spectrum of the explosive 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) has been measured using a conventional Fourier transform infrared spectroscopy and by terahertz pulsed spectroscopy. Seven absorption features in the spectral range of 5–120cm−1 have been observed and identified as the fingerprint of RDX. Furthermore, the spatial distribution of individual chemical substances including RDX, has been mapped out using reflection terahertz spectroscopic imaging in combination with component spatial pattern analysis. This is the terahertz spectroscopy and chemical mapping of explosives obtained using reflection terahertz measurement, and represents a significant advance toward developing a terahertz pulsed imaging system for security screening of explosives.
Flux-flow critical-state susceptibility of superconductors
Authors: Chen D.-X. , Pardo E. , Sanchez A.
Published: June 2005

The field-amplitude Hm and circular frequency ω dependent ac susceptibility, χ=χ′−jχ″, of a hard superconducting cylinder with flux-flow type current-voltage characteristic is calculated. A remarkable feature of the resultant χ(Hm,ω) is that both the maximum χ″, χm″, and dlgHm(χm″)∕dlgω increase with increasing ω. This behavior is observed in actual Bi-2223/Ag tapes and YBa2Cu3O7−δ-coated conductors. Our result provides a useful tool to study the intergranular critical state in high-temperature superconductors.
Effect of annealing temperature ramp rate on bubble formation in helium-implanted silicon
Authors: Simpson Todd W. , Mitchell Ian V.
Published: June 2005

We have implanted He3 into Si(100) at 1.0MeV ion energy and to fluences ranging between 2×1015 and 2×1016cm−2, followed by annealing at 700°C. Heating ramp rates have been systematically varied over more than two decades (0.3°C∕sto100°C∕s) at each fluence. The retention of He3 is measured through the He3(d,p)He4 nuclear reaction yield. We show that gas retention can be varied by more than an order of magnitude even while the other anneal parameters—anneal temperature and anneal time—are maintained constant. Cross-sectional scanning electron micrographs confirm the presence of planetarylike cavity structures at a depth closely matching that calculated for the damage peak.
Fabrication of n-ZnO:Al∕p-SiC(4H) heterojunction light-emitting diodes by filtered cathodic vacuum arc technique
Authors: Yuen Clement , Yu S. F. , Lau S. P. , Rusli  , Chen T. P.
Published: June 2005

We report the low-temperature (∼150°C) fabrication of n-ZnO:Al∕p-SiC(4H) heterojunction light-emitting diodes by filtered cathodic vacuum arc technique. Diodelike rectifying current-voltage characteristics, with turn-on voltage of ∼3.8V and low reverse leakage current of <10−2μA, were measured at room temperature. In addition, ultraviolet emission with peak wavelength of ∼385nm and full width at half maximum of ∼20nm are observed at a forward biased voltage of ∼7.4V. The ultraviolet electroluminescence from the heterojunction is originated from the exciton-exciton scattering inside the n-ZnO:Al film.
Bulk metallic glass formation in Zr–Cu–Fe–Al alloys
Authors: Jin Kaifeng , Löffler Jörg F.
Published: June 2005

We have discovered a series of bulk metallic glass-forming alloys of composition (ZrxCu100−x)80(Fe40Al60)20 with x=68–77 and have investigated them by x-ray diffraction, small-angle neutron scattering, and differential scanning calorimetry. All of these alloys exhibit a calorimetric glass transition temperature of 670K<Tg<687K and a large undercooled liquid region of widths 73–86 K. The best glass-forming ability is obtained for x≈72.5, i.e., for the alloy Zr58Cu22Fe8Al12. In rod shape this alloy has a critical casting thickness of 13 mm, as verified by detailed casting experiments, while alloys with x=68 and 77 can still be cast to a thickness of 5 mm. Furthermore, the region where glassy samples with a thickness of 0.5 mm can be prepared extends from x=62–81. The best glass-former, Zr58Cu22Fe8Al12, has a tensile yield strength of 1.71 GPa and shows an elastic limit of 2.25%. This new class of Ni-free Zr-based alloys is potentially very interesting for biomedical applications.
Self-assembly of Ge quantum dots on Si(100)-2×1 by pulsed laser deposition
Authors: Hegazy M. S. , Elsayed-Ali H. E.
Published: June 2005

Self-assembled Ge quantum dots are grown on Si(100)-2×1 by pulsed laser deposition. The growth is studied by in situ reflection high-energy electron diffraction and postdeposition atomic force microscopy. After the completion of the wetting layer, transient hut clusters, faceted by different planes, are observed. When the height of these clusters exceeded a certain value, the facets developed into {305} planes. Some of these huts become {305}-faceted pyramids as the film mean thickness was increased. With further thickness increase, dome clusters developed on the expense of these pyramids.
Dynamics of the formation of polymeric microstructures induced by electrohydrodynamic instability
Authors: Wu Ning , Russel William B.
Published: June 2005

We perform two-dimensional simulations of an electrohydrodynamic patterning process for a mask-gap-polymer-substrate sandwich. The simulations help us identify the intrinsic pattern resulting from nonlinear interactions to be hexagonal when the mask is unpatterned, consistent with experimental observations. The dynamic evolution of the thin polymer layer under a patterned mask shows that the pillars start to form from corners, propagate along edges, and then grow inwards. This growth sequence, identical to experimental observations, creates a square pattern under a square mask, a hexagonal pattern under a triangular mask, etc. Besides the hexagonal pattern, simulations indicate the conditions under which various different patterns that have been observed in experiments should form.
Hydrogen-selective sensing at room temperature with ZnO nanorods
Authors: Wang H. T. , Kang B. S. , Ren F. , Tien L. C. , Sadik P. W. , Norton D. P. , Pearton S. J. , Lin Jenshan
Published: June 2005

The sensitivity for detecting hydrogen with multiple ZnO nanorods is found to be greatly enhanced by sputter-depositing clusters of Pd on the surface. The resulting structures show a change in room- temperature resistance upon exposure to hydrogen concentrations in N2 of 10–500ppm of approximately a factor of 5 larger than without Pd. Pd-coated ZnO nanorods detected hydrogen down to <10ppm, with relative responses of >2.6% at 10ppm and >4.2% at 500ppm H2 in N2 after a 10min exposure. There was no response at room temperature to O2. Approximately 95% of the initial ZnO conductance after exposure to hydrogen was recovered within 20s by exposing the nanorods to either air or pure O2. This rapid and easy recoverability make the Pd-coated nanorods suitable for practical applications in hydrogen-selective sensing at ppm levels at room temperature with <0.4mW power consumption.
Unidirectional laser emission from polymer-based spiral microdisks
Authors: Ben-Messaoud T. , Zyss J.
Published: June 2005

Lasing emission has been observed in optically pumped DCM-poly(methyl methacrylate)-based spiral-shaped micropillar cavities. By transverse ring shaping of the pump beam, unidirectional laser emission is being clearly favored. The resulting improved far-field directionality evidenced by our imaging technique is shown to originate from the notch of the spiral microcavities.
Absence of the enhanced intra-4f transition cross section at 1.5μm of Er3+ in Si-rich SiO2
Authors: Mertens H. , Polman A. , Aarts I. M. P. , Kessels W. M. M. , van de Sanden M. C. M.
Published: June 2005

We present measurements of the optical absorption cross section of the I15∕24→I13∕24 transition at 1.5μm of Er3+ ions embedded in SiO2 and Si-rich oxide, using cavity ringdown spectroscopy on thin films. The peak absorption cross section for Er3+ embedded in Si-rich oxide (10at.% excess Si) was found to be (8±2)×10−21cm2 at 1536nm, similar to typical values for Er embedded in SiO2. The data imply that the silicon nanoclusters incorporated in Si-rich oxide do not enhance the peak cross section of the Er3+ I15∕24−I13∕24 transition by 1-2 orders of magnitude, contrary to what has been reported in earlier work.
IFN-γ-induced immune adaptation of the proteasome system is an accelerated and transient response
Authors: Heink Sylvia , Ludwig Daniela , Kloetzel Peter-M. , Krüger Elke
Published: June 2005

Peptide generation by the proteasome is rate-limiting in MHC class I-restricted antigen presentation in response to IFN-γ. IFN-γ-inducedde novoformation of immunoproteasomes, therefore, essentially supports the rapid adjustment of the mammalian immune system. Here, we report that the molecular interplay between the proteasome maturation protein (POMP) and the proteasomal β5i subunit low molecular weight protein 7 (LMP7) has a key position in this immune adaptive program. IFN-γ-induced coincident biosynthesis of POMP and LMP7 and their direct interaction essentially accelerate immunoproteasome biogenesis compared with constitutive 20S proteasome assembly. The dynamics of this process is determined by rapid LMP7 activation and the immediate LMP7-dependent degradation of POMP. Silencing of POMP expression impairs recruitment of both β5 subunits into the proteasome complex, resulting in decreased proteasome activity, reduced MHC class I surface expression, and induction of apoptosis. Furthermore, our data reveal that immunoproteasomes exhibit a considerably shortened half-life, compared with constitutive proteasomes. In consequence, our studies demonstrate that the cytokine-induced rapid immune adaptation of the proteasome system is a tightly regulated and transient response allowing cells to return rapidly to a normal situation once immunoproteasome function is no longer required.
Iron metabolism in copper-deficient rats
Authors: Marston H. R. , Allen Shirley H. , Swaby S. L.
Published: June 2005

1. The effects of ingestion of diets deficient in both copper and iron on storage of these elements and on the red cell indices have been studied in rats.

2. Injection of Cu into rats whose stores of Cu had been virtually exhausted resulted in a temporary increase in the concentration of plasma Fe and depletion of the Fe stored in the liver. Storage of Fe in the spleen seemed to be affected somewhat differently from that in the liver.

3. Fe injected into Cu-deficient rats was transported to storage sites but, although the plasma Fe concentration was presumably transiently increased thereby, there was no lasting effect.

4. The hypotheses that Cu mediates in the release of Fe from ferritin and that of Osaki, Johnson & Frieden (1966) that caeruloplasmin promotes the rate of Fe-saturation of apotransferrin are discussed.
A theoretical consideration of the effect of preventing rumen fermentation on the efficiency of utilization of dietary energy and protein in lambs
Authors: Black J. L.
Published: June 2005

1. The effect of preventing rumen fermentation of feed on the utilization of energy and protein by growing lambs has been studied by theoretical means.

2. Initially, the differences in feed utilization resulting from microbial fermentation compared with digestion by host enzymes were estimated. It was assumed that a diet containing 85% of unspecified carbohydrate and 15% casein was placed directly into the rumen (ruminant lamb) or abomasum (non-ruminant lamb) of animals weighing 20 kg, and that in both instances the diet was completely digested. In the non-ruminant lamb from 39 to 45% more net energy was available for maintenance, and from 22 to 61% more net energywas available for production, than in the ruminant lamb. The smaller differences applied to concentrate diets and the larger differences to highly fibrous diets. When dietary protein was completely degraded by microbes approximately 50% less protein was absorbed from the small intestine in the ruminant lamb than in the non-ruminant lamb. It is suggested that this may significantly reduce tissue synthesis and growth in early-weaned lambs weighing less than 30 kg, but it may not limit growth in heavier animals.

3. Because part of the food of ruminants generally escapes fermentation and is digested by enzymes in the small intestine, and because part of the food of non-ruminants is fermented in the hind-gut, the estimates were adjusted accordingly. In this situation the utilization of digested energy in the non-ruminant lamb was from 30 to 45 % more efficient for maintenance and from 10 to 60 % more efficient for production than in the ruminant lamb. Some dietary proteins are so resistant to microbial degradation that a lower efficiency of utilization in the ruminant lamb when these proteins are given could only result from a limit in availability of energy.

4. Since ruminants digest crude fibre more efficiently than non-ruminants, it was calculated that the level of dietary crude fibre must exceed at least 22%, and in some instances 35%, of the dry matter before the ruminant digestive system results in a better utilization of dietary energy in lambs. Thus, many common feeding-stuffs would be more efficiently used by lambs if they by-passed the rumen. The possible limitations to the adoption of this procedure are discussed.

5. The present techniques available for reducing the degradation of food within the rumen are outlined. It is suggested that an improvement in food utilization in ruminants could be achieved by feeding fats or formaldehyde-treated fat-casein complexes in solid diets, or alternatively, by feeding liquid diets which activate the reticular groove.
The influence of sex and age on the deposition of L-xyloascorbic acid in tissues of guinea-pigs
Authors: Hughes R. E. , Jones P. R.
Published: June 2005

1. Young male and female guinea-pigs of similar age and male guinea-pigs of various ages were given daily oral supplements of vitamin C (L-xyloascorbic acid) (AA) on a body-weight basis for periods of 10–15 d and the resulting concentration of AA in several organs was determined.

2. There was no difference between the sexes in the concentrations of AA in the adrenal glands and spleen. The concentration of AA in the spleen, adrenal glands and eye lens was significantly lower in older animals, and in brain it was significantly higher than the corresponding values for the young guinea-pigs.

3. The tissue deposition after oral administration of AA for 10 d was compared with that resulting from intramuscular injection of the same quantity of AA over 10 d in males aged 60 d, males aged 500 d and females aged 500 d. In the 60-d-old guinea-pigs intramuscular injection raised the concentration of AA in the spleen and adrenal glands 35% and 50% respectively above that resulting from oral dosing. In the older guinea-pigs (500 d) the corresponding values were 108% and 127% respectively. It is concluded that reduced gastrointestinal absorption is, at least in part, responsible for the low AA concentrations in certain organs from older guinea-pigs. In the 500-d-old guinea-pigs there was no significant difference between the AA levels in the spleen, adrenals and brain of the two sexes, but AA level in the lens of females was significantly lower than that in males, irrespective of the mode of administration of the AA.
Iodine metabolism in children and women with endemic goitre in Ceylon
Authors: Deo M. G. , Subramanian T. A. V.
Published: June 2005

1. Iodine metabolism was studied using labelled sodium iodide in subjects with endemic goitre which is prevalent in the south-west part of Ceylon, where the iodine content of the drinking water was shown to be low. The study was confined mostly to children of school age.

2. The patients showed raised thyroidal uptake of 181I and 48 h serum protein-bound radio-active iodine, lowered plasma inorganic iodide and urinary iodide.

3. These findings suggest that the goitre which is endemic in Ceylon is due to environmental iodine deficiency rather than to a goitrogen.
Cranial transillumination in early and severe malnutrition
Authors: Jaime Rozovski N. , Fernando Novoa S. , Jorge Abarzúa F. , Fernando Mönckeberg B.
Published: June 2005

1. By means of a cranial transillumination method used in conjunction with lumbar and bregmatic punctures, an increase in the space which contains the cerebro-spinal fluid in the cranial region is suggested in children with severe marasmic malnutrition.

2. The results appear to indicate that this is due to a diminished brain size, creating a space in the interior of the cranium which secondarily fills with cerebro-spinal fluid.
Artificial rearing of pigs
Authors: Braude R. , Newport M. J. , Porter J. W. G.
Published: June 2005

1. Baby pigs were removed from the sow 36–48 h after birth and reared on a diet of reconstituted whole-milk powder until 28 d of age. The whole milk was either mildly or severely heated before spray-drying; the severe heating completely denatured the whey proteins.

2. When the two milks were given at a high level of intake, either at hourly intervals or twice daily, severe scouring and some deaths occurred, the incidence being higher among pigs receiving the severely heated milk. The severe heat treatment also reduced the nutritive value of the milk powder as measured by the performance of the pigs during the 1st week of life. However, no difference in the nutritive value of the two milks was apparent for the surviving pigs over the whole experimental period.

3. There were no deaths when the two milks were given at a moderate level of intake and at hourly intervals. The effect of heat treatment on performance was similar to that at the high level of intake.

4. The apparent digestibility of the nitrogen in the diet was similar for both milks. However, balance trials could not be carried out when scouring occurred, when differences between the milks were most likely to be apparent. The N retention was similar with both milks at 7 d of age, although retention was higher when the severely heated milk was given to pigs between 14 and 21 d of age.

5. The digestion of the two milks was studied in 28-d-old pigs. The ability of the severely heated milk to clot in the stomach was greatly reduced compared with that of the mildly heated milk, but the performance of the pigs was unaffected. No other differences in the digestion of the milks were found. The ability of the diet to clot in the stomach appeared to be unimportant at this age.

6. It is possible that a reduction in the clotting ability of the severely heated milk was responsible for the decreased efficiency of digestion during the 1st week of life.
Measurement of the bacterial nitrogen entering the duodenum of the ruminant using diaminopimelic acid as a marker
Authors: Hutton K. , Bailey F. J. , Annison E. F.
Published: June 2005

1. A technique for the separation and colorimetric estimation of 2, 4-diaminopimelic acid (DAP) using automated ion-exchange chromatography coupled with an acid ninhydrin detection system is described.

2. Only traces of DAP were found in rumen protozoa and no DAP was detected in rumen fluid prepared by ultracentrifugation or dialysis.

3. The concentration of DAP in rumen bacteria from sheep on a constant feeding regimen, and the ratio of nitrogen to DAP for these bacteria were found to be constant over a 3-month period.

4. The method has proved suitable for the estimation of bacterial N in the duodenal digesta of ruminants.

5. The contribution of bacterial N to the total N leaving the abomasum of a lactating cow fitted with a permanent re-entrant cannula in the duodenum was found to be 50%.
Protein-calorie deficiency in rats
Authors: Stewart R. J. C. , Sheppard Hilda G.
Published: June 2005

1. Rats born of well-fed mothers and maintained from weaning on diets having protein values of NDpCal% = 10 or 5 were mated at 3 months of age with well-fed males.

2. The litters produced by the malnourished mothers weighed significantly less (P > 0.01) than those from the well-fed group.

3. The average number of individuals per litter was lower in the malnourished than in the well-fed group, but the difference was not statistically significant ( P < 0.0 5 ).

4. The congenitally malnourished litters weighed less than the well-fed even when litters of equal number were compared.

5. The differences in litter weights were not related to the length of gestation, which was similar in both groups.

6. There was a high neonatal death rate (63%) among the congenitally malnourished animals and the survivors grew very slowly so that at 5 weeks of age they weighed only half as much as the well-fed controls.
Nucleic acid metabolism in the ruminant
Authors: Smith R. H. , Mcallan A. B.
Published: June 2005

1. Concentrations of nucleic acid nitrogen and other nitrogenous constituents were estimated in digesta taken from the proximal duodenum of calves which were given, either, one of a number of stall diets or pasture. These concentrations were compared, using polyethylene glycol (PEG) as a non-absorbed marker, with corresponding concentrations in rumen fluid and ileal contents.

2. There was little net change in amounts of RNA or DNA between rumen and duodenum relative to PEG, but there was a marked increase in amounts of total-N. In duodenal digesta, for any one animal given most diets, nucleic acid-N formed a fairly constant percentage (8–11 for different animals) of the total non-ammonia-N. This value was lower (by about 3) than the corresponding percentage in rumen fluid. Comparison of nucleic acid-N: total-N ratios in duodenal contents and bacteria suggested that, for these diets, about 40–55% of the non-ammonia-N in duodenal contents was of microbial origin.

3. During passage of digesta between the duodenum and ileum the mean percentage disappearances of total-N, RNA and DNA were estimated to be about 67, 85 and 75 respectively. There was evidence that these values varied with the amounts of the constituents entering the duodenum.

4. Ammonia was absorbed in the omasum-abomasum only when concentrations in rumen fluid were high (40 mM), but even moderate concentrations of ammonia entering the duodenum (3 mM) were efficiently absorbed (about 90%) in the small intestine.
Effect of sex hormones on fasting serum triglycerides in baboons given high-sucrose diets
Authors: Coltart T. M , Macdonald I
Published: June 2005

1. The incorporation of [14C]sucrose in to serum triglyceride was shown to increase in both male and female baboons after a period of high sucrose intake. During the same period of high sucrose intake there was an increase in the fasting serum triglyceride concentration of the male baboons but not of the females.

2. When the male baboons were given a parenteral oestrogen preparation in addition to the sucrose diet the increase in fasting serum triglycerides was greatly reduced but there was little alteration in the extent of the incorporation of sucrose into serum triglyceride compared to that with the diet and no oestrogen.

3. A parenteral testosterone preparation given to the female baboons in addition to sucrose diet had no effect on either the extent of incorporation of sucrose into triglyceride the fasting serum concentrations of triglyceride.

4. The findings suggest that the differing patterns of fasting triglyceride response in the male and female baboons to the sucrose diet may have resulted from oestrogen enhancing the removal of triglyceride from the serum of the female animals.
The influence of level of grain intake on protein digestion in the intestine of cattle
Authors: Neudoerffer T. S. , Leadbeater P. A. , Horney F. D , Bayley H. S
Published: June 2005

1. Protein digestion in the gastro-intestinal tract of cattle receiving diets with either low or high content of maize was investigated. Digesta obtained from the duodenum and ileum were separated into three fractions; soluble, microbial and particulate, and the amino acid composition of the three fractions and that of the total digesta were determined. The proportion of particulate material digested in the intestine was less from the high-maize than from the low-maize diet, but more of the particulate fraction entered the duodenum from the high-maize than from the low-maize diet, so the absolute amount of particulate fraction which was digested was greater for the high-maize diet.

2. More protein was digested in the rumen from the low-maize diet (high-roughage) than from the other diet. Total digestion of protein from the low-maize diet was also higher.

3. Although more protein from the high-maize than from the low-maize diet reached the duodenum, the protein from the low-maize diet was more digestible in the intestine, so the total amount of dietary protein digested in the intestine was the same for both rations.
Nitrogen metabolism in sheep
Authors: Mathison G. W. , Milligan L. P.
Published: June 2005

1.15NH4Cl was continuously infused for periods of 120–216 h into the rumens of sheep which were allowed to feed 2 out of every 10min. These treatments achieved steady metabolic states and allowed the assessment of nitrogen conversions by means of tracer methodology. The sheep were given either a barley diet or one of three hay diets. In two trials, the flow of abomasal material was determined using lignin and polyethylene glycol as markers. The amounts of dry matter (DM), gross energy, total N, soluble N, microbial N and microbial DM in abomasal digesta, and the concentration of ammonia in the rumen liquor were measured. The concentrations of15N in the N of urine, faeces, rumen and abomasal bacteria and protozoa, rumen and abomasal bacterial and protozoal protein, abomasal particulate matter and in rumen ammonia were determined.

2. Comparisons of the steady-state concentrations of15Nin the microbes with that in rumen ammonia indicated that from 50 to 65% of the bacterial N and from 31 to 55% of the protozoal N were derived from rumen ammonia in vivo.

3. An amount of N equivalent to 60–92% of the daily intake was transformed into ammonia N in the runen.

4. Some 17–54% of the ammonia was absorbed from the rumen, but this was not readily converted into urea.

5. Microbial growth in the rumen resulted in the assimilation of 1.7–2.6 g N/100 g DM fermented.

6. The generation-time of bacterial protein in the rumen was calculated from the rate of in- crease of15N concentration in this fraction, and values of 38 and 42 h were obtained for sheep given barley and hay diets respectively.

7. The combined results allowed quantitative estimates to be made of the complete metabolism of rumen N, and from these the possibility of fixation of N gas in the rumen was suggested.
Composition of human adipose tissue from deep and subcutaneous sites
Authors: BROOK C. G. D.
Published: June 2005

1. Adipose tissue was obtained simultaneously from subcutaneous and deep sites in children undergoing elective surgery, and from different subcutaneous sites in adults. The lipid content and fatty acid composition were measured using gas-liquid chromatography and the number of cells counted after fixation in osmium tetroxide. The mean amount of lipid per cell was used as a measure of the size of the cells.

2. Cells from deep sites in children were significantly smaller (P > 0.001) than those from subcutaneous sites in the same individual. Cells from different subcutaneous sites were of similar size.

3. The fatty acid composition of the lipids was similar in tissue taken from the abdominal wall and from deep sites.

4. The fatty acid composition of adipose tissue from the lower leg showed an increase in the monounsaturated fatty acids and a decrease in the saturated fatty acids compared with the fatty acid composition of tissue from other subcutaneous sites.
Arsanilic acid, sodium salicylate and bromide salts as potential growth stimulants for pigs receiving diets with and without copper sulphate
Authors: Barber R. S , Braude R , Mitchell K. G
Published: June 2005

1. Results are presented of three experiments involving 112 individually fed pigs, covering the growing period between 20 and 90 kg live weight, in which the potential performance-stimulating properties of three different compounds were studied in relation to those of a dietary supplement of 250 mg Cu/kg diet.

2. The three compounds studied and the levels of supplementation used (mg/kg diet) were: Expt I arsanilic acid (100), Expt 2 sodium salicylate (200), Expt 3 a mixture of bromide salts (200); each was added to the diets either alone or with 250mg Cu/kg diet given as CuSO4, 5H2O.

3. The diets were given wet, ‘to appetite’ twice daily up to a daily maximum of 3 kg feed/pig. Measurements of length and of back-fat thickness at a number of points were made on all carcasses at slaughter.

4. Arsanilic acid and sodium salicylate alone gave growth responses similar to those obtained with Cu alone, whereas the bromide salt had no effect on performance. None of the three compounds when added to diets in conjunction with 250mg Cu/kg diet gave results superior to those obtained with the Cu supplement alone.

5. When added to the diets alone, none of the three compounds tested nor Cu had any marked effect on any of the carcass measurements.

6. Arsanilic acid reduced total liver weight and markedly reduced the large increase in total liver Cu stores that resulted from supplementation of the diets with 250 mg Cu/kg diet.