bluuebunny/crossref_metadata_2025 huggingface dataset:
Strain evolution in Al conductor lines during electromigration
Authors: Zhang H. , Cargill G. S. , Ge Y. , Maniatty A. M. , Liu W.
Published: January 2009

Monochromatic and white beam synchrotron x rays were used to study the deviatoric strains and full elastic strains in passivated Al conductor lines with near-bamboo structures during electromigration (EM) at 190 °C. A strong strain gradient formed in the upstream part of the Al lines. Strains along the downstream part of the lines were smaller and more scattered. Numerical analysis using the Eshelby model and finite element method (FEM) calculations suggest that the moving of atoms during EM in these near-bamboo Al lines is dominated by top and/or bottom interface diffusion, which differs from the reported results for nonbamboo, polycrystalline Al conductor lines, where EM is mainly along the grain boundaries. Local strain measurements and FEM calculations indicate that the EM flux is also nonuniform across the width of the conductor line because of stronger mechanical constraint by the passivation layer near the edges of the line. Plastic deformation is observed during EM by changes in the Laue diffraction patterns. The effective valence |Z∗|=1.8±0.4 is determined from the measured strain gradient.
Lambda-doublet specificity in the low-temperature capture of NO(X Π21/2) in low rotational states by C+ ions
Authors: Auzinsh M. , Dashevskaya E. I. , Litvin I. , Nikitin E. E. , Troe J.
Published: January 2009

Following our general approach to Λ-doubling specificity in the capture of dipolar molecules by ions [M. Auzinsh et al., J. Chem. Phys. 128, 184304 (2008)], we calculate the rate coefficients for the title process in the temperature range 10−4<T<102 K. Three regimes considered are as follows: (i) nonadiabatic capture in the regime of high-field Stark effect with respect to the Λ-doubling components, (10−1<T<102 K), (ii) adiabatic capture in the regime of intermediate Stark effect (10−3<T<10−1 K), and (iii) adiabatic capture in the limit of very low temperatures (T⪡10−3 K) in the regime of quadratic Stark effect with respect to the Λ-doubling and hyperfine components. The results predict a high specificity of the capture rates with respect to the Λ-doublet states even under conditions when the collision energy of the partners strongly exceeds the Λ-doubling splitting.
Femtosecond time-resolved absorption anisotropy spectroscopy on 9,9′-bianthryl: Detection of partial intramolecular charge transfer in polar and nonpolar solvents
Authors: Takaya Tomohisa , Hamaguchi Hiro-o , Iwata Koichi
Published: January 2009

Femtosecond time-resolved absorption anisotropy spectroscopy by multichannel detection has been developed. The charge transfer (CT) character and dynamics of the UV-photoexcited 9,9′-bianthryl (BA) in heptane, acetonitrile, and ethanol are revealed with this method. The transient absorption spectra are decomposed into two absorption components with different anisotropy values by the absorption anisotropy spectra. The decomposition results show two absorption bands having different anisotropy values or different directions of the transition dipole moment. One band that has the transition dipole perpendicular to the central C–C bond has almost an identical spectral shape with transient absorption of anthracene in the singlet excited state. This band is assigned to a transition in a locally excited anthracene ring. The other band is broad and structureless. This band is assigned to partial charge transfer (PCT) absorption because its transition dipole moment is parallel to the central C–C bond. Because the PCT band is observed in a nonpolar solvent heptane as well as in polar solvents, the PCT occurs in both nonpolar and polar solvents. The PCT band rises within the instrumental response, indicating that the PCT takes place immediately after the photoexcitation. In acetonitrile, the CT component shows a significant blueshift, indicating the formation of the stabilized CT state from the PCT state. In ethanol, the CT band does not show a spectral shift, suggesting that the stabilization is smaller than in acetonitrile. From these results, a new kinetic model on the intramolecular CT in BA is discussed.
Electronic structure of C60F36 studied by quantum-chemical modeling of experimental photoemission and x-ray absorption spectra
Authors: Bulusheva L. G. , Okotrub A. V. , Shnitov V. V. , Bryzgalov V. V. , Boltalina O. V. , Gol’dt I. V. , Vyalikh D. V.
Published: January 2009

This paper presents an experimental and theoretical study of the electronic structure of the fluorinated fullerene C60F36. UV photoemission spectroscopy (UPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy have been used for probing the density of electronic states in the valence and conduction bands of the compound. An assignment of spectral features was carried out using the results of ab initio B3LYP ground-state calculations of the electronic structure of C60F36. The sample of C60F36 is a mixture of three isomers. The calculations of the density of occupied states of these isomers revealed only a small effect of the π-system organization on the UPS profile. It was demonstrated that the CK-edge NEXAFS spectrum of the fluorinated fullerene can be successfully modeled using the (Z+1) approach properly treating the core hole impact on the spectral profile.
Single molecule kinetics under stochastic gating
Authors: Zheng Yujun
Published: January 2009

In this note, we generally calculate the statistical blinking properties of single molecule based on the generating function approach developed recently. Specifically, we investigate the statistical variables of single molecule blinking kinetics under the stochastic gating.
Barrierless reactions between two closed-shell molecules. II. Dynamics of F2+CH3SSCH3 reaction
Authors: Shao Hua-Chieh , Xie Tingxian , Lu Yu-Ju , Chang Chih-Hsuan , Pan Jun-Wei , Lin Jim J.
Published: January 2009

A second example of a barrierless reaction between two closed-shell molecules is reported. The reaction F2+CH3SSCH3 has been investigated with crossed molecular beam experiments and ab initio calculations. Compared with previous results of the F2+CH3SCH3 reaction [J. Chem. Phys. 127, 101101 (2007); J. Chem. Phys. 128, 104317 (2008)], a new product channel leading to CH3SF+CH3SF is observed to be predominant in the title reaction, whereas the anticipated HF+C2H5S2F channel is not found. In addition, the F+C2H6S2F product channel, the analog to the F+C2H6SF channel in the F2+CH3SCH3 reaction, opens up at collision energies higher than 4.3 kcal/mol. Angular and translational energy distributions of the products are reported and collision energy dependences of the reaction cross section and product branching ratio are shown. The reaction barrier is found to be negligible (⪡1 kcal/mol). Multireference ab initio calculations suggest a reaction mechanism involving a short-lived intermediate which can be formed without activation energy.
Nonparametric density estimation and optimal bandwidth selection for protein unfolding and unbinding data
Authors: Bura E. , Zhmurov A. , Barsegov V.
Published: January 2009

Dynamic force spectroscopy and steered molecular simulations have become powerful tools for analyzing the mechanical properties of proteins, and the strength of protein-protein complexes and aggregates. Probability density functions of the unfolding forces and unfolding times for proteins, and rupture forces and bond lifetimes for protein-protein complexes allow quantification of the forced unfolding and unbinding transitions, and mapping the biomolecular free energy landscape. The inference of the unknown probability distribution functions from the experimental and simulated forced unfolding and unbinding data, as well as the assessment of analytically tractable models of the protein unfolding and unbinding requires the use of a bandwidth. The choice of this quantity is typically subjective as it draws heavily on the investigator’s intuition and past experience. We describe several approaches for selecting the “optimal bandwidth” for nonparametric density estimators, such as the traditionally used histogram and the more advanced kernel density estimators. The performance of these methods is tested on unimodal and multimodal skewed, long-tailed distributed data, as typically observed in force spectroscopy experiments and in molecular pulling simulations. The results of these studies can serve as a guideline for selecting the optimal bandwidth to resolve the underlying distributions from the forced unfolding and unbinding data for proteins.
Vibrational relaxation of trapped molecules in solid matrices: OH(A Σ2+;v=1)/Ar
Authors: Ree J. , Kim Y. H. , Shin H. K.
Published: January 2009

The vibrational relaxation of OH(A Σ2+;v=1) embedded in solid Ar has been studied over 4–80 K. The interaction model is based on OH undergoing local motions in a cage formed by a face-centered cubic stacking where the first shell atoms surround the guest and connect it to the heat bath through 12 ten-atom chains. The motions confined to the cage are the local translation and libration-rotation of OH and internal vibrations in OH⋯Ar, their energies being close to or a few times the energies of nearby first shell and chain atoms. The cage dynamics are studied by solving the equations of motion for the interaction between OH and first shell atoms, while energy propagation to the bulk phase through lattice chains is treated in the Langevin dynamics. Calculated energy transfer data are used in semiclassical procedure to obtain rate constants. In the early stage of interaction, OH transfers its energy to libration-rotation intramolecularily and then to the vibrations of the first shell and chain atoms on the time scale of several picoseconds. Libration-to-rotational transitions dispense the vibrational energy in small packages comparable to the lattice frequencies for ready flow. Energy propagation from the chains to the heat bath takes place on a long time scale of 10 ns or longer. Over the solid argon temperature range, the rate constant is on the order of 106 s−1 and varies weakly with temperature.
Effect of retrapping on photostimulated luminescence in Sr3SiO5:Eu2+, Dy3+ phosphor
Authors: Sun Xiaoyuan , Zhang Jiahua , Zhang Xia , Luo Yongshi , Hao Zhendong , Wang Xiao-jun
Published: January 2009

Sr 3 SiO 5 : Eu 2 + , Dy3+ exhibits a strong orange phosphorescence and photostimulated luminescence, originating from 4f65d-4f7 transition of Eu2+, after ultraviolet exposure. Shallow and deep traps are evidenced by thermoluminescence spectrum and decay curve of phosphorescence, which consists of a very fast and a slow component. The photostimulated luminescence presents a slow rising and a falling edge as an infrared excitation at 808 nm is turned on and off, respectively. This is attributed to the result of electron retrapping by shallow traps based on the analysis of dynamical process in photostimulated luminescence involved in photostimulated depopulation of deep traps. The electrons retrapped by deep traps is also demonstrated in the time interval between photostimulation off and on, which results in an enhanced rising edge relative to the former falling edge.
Model surface conductivity effect for the electromagnetic heat shield in re-entry flight
Authors: Matsuda Atsushi , Otsu Hirotaka , Kawamura Masaaki , Konigorski Detlev , Takizawa Yuji , Abe Takashi
Published: January 2009

Effects of model surface conductivity on shock layer enhancement by an applied magnetic field in weakly ionized supersonic plasma flow with a large Hall parameter (β∼300) was investigated experimentally. The shock layer structures of test models of two kinds were measured using laser absorption spectroscopy, in the large Hall parameter situation. One was an insulated model; the other was a conductive spherical blunt model. The shock layer enhancement phenomenon by the applied magnetic field was more pronounced for the insulated model than for the conductive model. This tendency agrees with the computational fluid dynamics result, at least qualitatively.
Magnetic properties of carbon materials prepared from polyvinyl chloride
Authors: Saito Tetsuji
Published: January 2009

Carbon materials were prepared by pyrolysis of polyvinyl chloride (PVC). Although PVC powder exhibited diamagnetic behavior, the carbon material prepared by pyrolysis at 1073 K exhibits paramagnetic behavior, while that prepared by pyrolysis at 1273 K exhibited ferromagnetic behavior. X-ray diffraction and Fourier transform infrared spectrometry studies revealed that the paramagnetic and ferromagnetic carbon materials consist of nanometer scale graphitelike grains within a highly disordered carbon matrix.
A comparative study of the magnetocaloric effect in RNi2 (R=Nd,Gd,Tb) intermetallic compounds
Authors: Plaza E. J. R. , de Sousa V. S. R. , von Ranke P. J. , Gomes A. M. , Rocco D. L. , Leitão J. V. , Reis M. S.
Published: January 2009

Conventional and anisotropic magnetocaloric effects were studied in cubic rare earth RNi2 (R=Nd,Gd,Tb) ferromagnetic intermetallic compounds. These three compounds are representative of small, null, and large magnetocrystalline anisotropy in the series, respectively. Magnetic measurements were performed in polycrystalline samples in order to obtain the isothermal magnetocaloric data, which were confronted with theoretical results based on mean field calculations. For the R=Tb case, we explore the crystalline electrical-field anisotropy to predict the anisotropic magnetocaloric behavior due to the rotation of an applied magnetic field of constant intensity. Our results suggest the possibility of using both conventional and anisotropic magnetic entropy changes to extend the range of temperatures for use in the magnetocaloric effect.
Density functional study on cage and noncage (Fe2O3)n clusters
Authors: Ding Xun-Lei , Xue Wei , Ma Yan-Ping , Wang Zhe-Chen , He Sheng-Gui
Published: January 2009

Both cage and noncage structures of (Fe2O3)n (n=2–6 and 10) clusters are studied using density functional theory. All the cage structures are stable without imaginary vibrational frequency but the global minima are the noncage clusters for most cases. Our results show that oxidation of Fe4On (n<6) clusters by O2 at room temperature is exothermic, while oxidation of n≥6 clusters is endothermic. This is in qualitative agreement with an experimental observation that only Fe4On+ (n≥6) clusters are produced in a laser vaporization source under saturated O2 growth conditions. Since (Fe2O3)n clusters have high stability and different structural and bonding properties from those of the bulk Fe2O3, they may serve as good models for predicting or interpreting novel properties of Fe2O3 nanomaterials.
Rietveld fitting of x-ray diffraction spectra for the double phase composites La0.7−xSr0.3Mn1−yO3−1.5(x+y)/(Mn3O4)y/3
Authors: Liu S. P. , Tang G. D. , Hao P. , Xu L. Q. , Zhang Y. G. , Qi W. H. , Zhao X. , Hou D. L. , Chen W.
Published: January 2009

The effects of lanthanum deficiency on the structural and magnetic properties of manganites with normal composition La0.7−xSr0.3MnO3 prepared by the sol-gel method with the highest heat treatment temperature at 800 °C have been investigated. X-ray diffraction (XRD) spectra indicate that the materials possess a single phase with the R3¯c perovskite structure for x≤0.05, and that they possess two phases with the R3¯c perovskite being the dominant phase and Mn3O4 being the second phase for x≥0.10. Using XRD analysis, these materials can be expressed as La0.7−xSr0.3Mn1−yO3−1.5(x+y)/(Mn3O4)y/3. On the basis of the thermal equilibrium theory of crystal defects, the ion ratios at the A, B, and O sites in the ABO3 perovskite phase were calculated. Those ion ratios were used in Rietveld fitting of the XRD spectra. It was found that the dependence of the Curie temperature TC on the content ratio RM4 of Mn4+ ions at B site is similar to that of the typical perovskite La1−xSrxMnO3.
Modeling two photon absorption cross sections of open-shell systems
Authors: Jha Prakash Chandra , Rinkevicius Zilvinas , Ågren Hans
Published: January 2009

We demonstrate the prospects of computing two photon absorption cross sections of open-shell systems by applying recently developed spin-restricted time-dependent density functional response theory using the pyrrole radical as an example. The spin multiplicity effects on two photon absorption cross sections of this species are investigated for the doublet, quartet, and sextet states. It is found that irrespective of the exchange-correlation functional employed, the two photon cross sections increase with the increase in spin multiplicity. This result indicates that two photon cross sections of paramagnetic compounds can be controlled by manipulating their spin states and this opens new possibilities for design of hybrid magneto-optical materials.
Macroscopic ferroelectricity and piezoelectricity in nanostructured BiScO3–PbTiO3 ceramics
Authors: Algueró M. , Amorín H. , Hungría T. , Galy J. , Castro A.
Published: January 2009

We have studied the macroscopic electrical properties of highly dense, nanostructured ceramics of BiScO3–PbTiO3 with high Curie temperature and piezoelectric activity. Materials were processed by spark plasma sintering of nanocrystalline powder obtained by mechanosynthesis. Results indicate that the nanostructured material still presents the ferroelectric transition above 700K. Ferroelectric switching is unambiguously demonstrated. Furthermore, ceramic disks were poled and their radial piezoelectric resonance was excited, which has not been achieved in nanostructured BaTiO3 ceramics.
Design of a double diaphragm shock tube for fluid disintegration studies
Authors: Stotz Ingo , Lamanna Grazia , Hettrich Harald , Weigand Bernhard , Steelant Johan
Published: January 2009

A double diaphragm shock tube facility for studying liquid-spray atomization and combustion-related phenomena at elevated pressures and temperatures is described. The present shock tube is specifically intended for the investigation of fundamental processes related to fluid disintegration and mixing under realistic engine conditions. Special features of the facility include a variable-area driver section to compensate for shock attenuation, a square test section to allow flow visualization in the postshock region, a skimmer to dispose part of the boundary layer, a heated, fast-response injector, a fully automated gas-filling system, and a new control system and electronics. Test times of the order of 2–5 ms are possible with reflected shock pressures up to 50 bar and temperatures of 2000 K. Details on the setup design, construction and operation are given. Particular emphasis is placed on the accuracy and reproducibility of the test conditions. To that aim, qualification tests have been performed to assess the shock tube performance in terms of effectiveness of the skimmer concept, the capability to compensate for boundary layer effects and the generation of uniform and reproducible test and injection conditions.
Electron heating in radio-frequency capacitively coupled atmospheric-pressure plasmas
Authors: Liu D. W. , Iza F. , Kong M. G.
Published: January 2009

In atmospheric-pressure plasmas the main electron heating mechanism is Ohmic heating, which has distinct spatial and temporal evolutions in the α and γ modes. In γ discharges, ionizing avalanches in the sheaths are initiated not only by secondary electrons but also by metastable pooling reactions. In α discharges, heating takes place at the sheath edges and in contrast with low-pressure plasmas, close to 50% of the power absorbed by the electrons is absorbed at the edge of the retreating sheaths. This heating is due to a field enhancement caused by the large collisionality in atmospheric-pressure discharges.
First-principles investigation of intrinsic defects and (N, O) impurity atom stimulated Al vacancy in Ti2AlC
Authors: Liao Ting , Wang Jingyang , Zhou Yanchun
Published: January 2009

We use first-principles calculations to study the energetics of intrinsic defects in Ti2AlC and the effect of N or O impurity atoms on the generation of Al vacancies. The insertion of impurity atoms lowers the vacancy formation energy of its neighboring Al. The formation of Al vacancies is related to the experimental observations of growth of AlN or Al2O3 nanowires and nanofibers on the surface of Ti2AlC. Since the growth of these nanostructures is controlled by the generation and migration of intrinsic defects, we propose that a tunable method for synthesis of such nanostructures is possible by controlling impurities.
Plasma-controlled adatom delivery and (re)distribution: Enabling uninterrupted, low-temperature growth of ultralong vertically aligned single walled carbon nanotubes
Authors: Tam Eugene , Ostrikov Kostya (Ken)
Published: January 2009

Large-scale (∼109 atoms) numerical simulations reveal that plasma-controlled dynamic delivery and redistribution of carbon atoms between the substrate and nanotube surfaces enable the growth of ultralong single walled carbon nanotubes (SWCNTs) and explain the common experimental observation of slower growth at advanced stages. It is shown that the plasma-based processes feature up to two orders of magnitude higher growth rates than equivalent neutral-gas systems and are better suited for the SWCNT synthesis at low nanodevice friendly temperatures.
Degenerate and nondegenerate lateral-mode patterns in quantum cascade lasers
Authors: Stelmakh Nikolai , Vasilyev Michael , Toor Fatima , Gmachl Claire
Published: January 2009

We experimentally investigate near-field lateral-mode patterns of 10–25-μm-wide quantum cascade wide-ridge lasers with few lateral modes using a 1-GHz-resolution spatially resolving midinfrared spectrometer. The results supported by simple box-model theory demonstrate that, depending on the laser geometry, one can either obtain lateral-mode frequency degeneracy or find the high-order lateral modes to be blueshifted or redshifted from the fundamental. We show that, with proper laser geometry, all longitudinal and lateral modes can be frequency nondegenerate and, therefore, be easily suited for spatiospectral mode combining to increase brightness.
Terahertz photoconductivity of Pb1−xSnxTe(In)
Authors: Khokhlov Dmitry , Ryabova Ludmila , Nicorici Andrey , Shklover Valery , Ganichev Sergey , Danilov Sergey , Bel’kov Vasily
Published: January 2009

We have analyzed photoconductivity in Pb1−xSnxTe(In) under the action of ∼100 ns long terahertz laser pulses with the wavelength varying from 90 to 280 μm in the temperature range 4.2–300 K. Strong photoresponse has been observed at all laser wavelengths used. Two types of photoresponse have been detected. Positive persistent photoconductivity, which is observed at T<10 K is due to photoexcitation of impurity states, whereas negative nonpersistent photoresponse prevailing at higher temperatures T∼25 K results from free carrier heating. Specific features of photoconductivity mechanisms are discussed.
Effect of Mo substitution on ferroelectric properties of Bi3.6Ho0.4Ti3O12 thin films prepared by sol-gel method
Authors: Guo Dongyun , Wang Chuanbin , Shen Qiang , Zhang Lianmeng , Li Meiya , Liu Jun
Published: January 2009

The series of (Bi0.9Ho0.1)4−2x/3Ti3−xMoxO12 (BHTM) (x=0, 0.9%, 1.5%, 3.0%, and 6.0%) thin films on Pt/Ti/SiO2/Si substrates is prepared by sol-gel method, and the effect of Mo content on the microstructure and ferroelectric properties of these films are investigated. When the Mo content is not excessive, the BHTM films consisted of the single phase of Bi-layered Aurivillius phase. The B-site substitution with high-valent cation of Mo6+, in Bi3.6Ho0.4Ti3O12 films, enhanced the 2Pr (remanent polarization) and reduced the 2Ec (coercive field) of these films. The BHTM thin film with x=1.5% exhibited the best electrical properties with 2Pr of 48.4 μC/cm2, 2Ec of 263.5 kV/cm, dielectric constant of 391 (at 1 MHz), good insulting behavior, as well as the fatigue-free characteristic.
Analysis and improvement of interfacial adhesion of growth-dominant Ge-doped SbTe phase change materials
Authors: Jeong Jeung-hyun , Ahn Hyung-Woo , Lee Suyoun , Kim Won Mok , Ha Jae-Geun , Cheong Byung-ki
Published: January 2009

A semiquantitative characterization of the interfacial adhesion of phase change materials is developed, which consists of determining critical adhesion temperature (TCA) via measuring the probability of adhesion failure with temperature using patterned films. By comparison of TCA values, Ge-doped SbTe (Ge-ST) is shown to have weaker adhesion than Ge2Sb2Te5 (GST), which results from its limited ability in relaxation of crystallization-induced stress. Nitrogen or oxygen doping in Ge-ST produces significant increase in TCA, close to that of GST. This improvement is due to smaller grain size of N-/O-doped Ge-ST, which facilitates the relaxation of the stress via grain boundary diffusion or sliding.
Temporal variation in δ13C, wood density and microfibril angle in variously irrigated Eucalyptus nitens
Authors: Drew David M. , Schulze E. Detlef , Downes Geoffrey M.
Published: January 2009

Wood can serve as a record of past climate, recording tree responses to changing conditions. It is also valuable in understanding tree responses to environment to optimise forest management. Stable carbon isotope ratios (δ13C), wood density and microfibril angle (MFA) are potentially useful wood property parameters for these purposes. The goal of this study was to understand how δ13C varied over time in response to cycles of soil drying and wetting and to variation in temperature in Eucalyptus nitens Deane & Maiden, in concert with wood density and MFA. δ13C increases did not necessarily occur when water stress was highest, but, rather, when it was relieved. Our hypothesis is that this was a result of the use of previously fixed carbohydrate reserves when growth and metabolic activity was resumed after a period of dormancy. MFA in particular showed concomitant temporal variation with δ13C. A peak in δ13C may not coincide temporally with an increase in water stress, but with a decrease, when higher growth rates enable the final incorporation of earlier stored photosynthate into mature wood. This has implications for using δ13C as a tool to understand past environmental conditions using radial measurements of wood properties. However, interpreting this data with other wood properties may be helpful for understanding past tree responses.
Sun-shade patterns of leaf carotenoid composition in 86 species of neotropical forest plants
Authors: Matsubara Shizue , Krause G. Heinrich , Aranda Jorge , Virgo Aurelio , Beisel Kim G. , Jahns Peter , Winter Klaus
Published: January 2009

A survey of photosynthetic pigments, including 86 species from 64 families, was conducted for leaves of neotropical vascular plants to study sun-shade patterns in carotenoid biosynthesis and occurrence of α-carotene (α-Car) and lutein epoxide (Lx). Under low light, leaves invested less in structural components and more in light harvesting, as manifested by low leaf dry mass per area (LMA) and enhanced mass-based accumulation of chlorophyll (Chl) and carotenoids, especially lutein and neoxanthin. Under high irradiance, LMA was greater and β-carotene (β-Car) and violaxanthin-cycle pool increased on a leaf area or Chl basis. The majority of plants contained α-Car in leaves, but the α- to β-Car ratio was always low in the sun, suggesting preference for β-Car in strong light. Shade and sun leaves had similar β,ε-carotenoid contents per unit Chl, whereas sun leaves had more β,β-carotenoids than shade leaves. Accumulation of Lx in leaves was found to be widely distributed among taxa: >5 mmol mol Chl−1 in 20% of all species examined and >10 mmol mol Chl−1 in 10% of woody species. In Virola elongata (Benth.) Warb, having substantial Lx in both leaf types, the Lx cycle was operating on a daily basis although Lx restoration in the dark was delayed compared with violaxanthin restoration.
Glucocorticoid receptor interaction with TrkB promotes BDNF-triggered PLC-γ signaling for glutamate release via a glutamate transporter
Authors: Numakawa Tadahiro , Kumamaru Emi , Adachi Naoki , Yagasaki Yuki , Izumi Aiko , Kunugi Hiroshi
Published: January 2009

An increase in glucocorticoid levels and down-regulation of BDNF (brain-derived neurotrophic factor) are supposed to be involved in the pathophysiology of depressive disorders. However, possible crosstalk between glucocorticoid- and BDNF-mediated neuronal functions in the CNS has not been elucidated. Here, we examined whether chronic glucocorticoid exposure influences BDNF-triggered intracellular signaling for glutamate release via a glutamate transporter. We found that chronic exposure to dexamethasone (DEX, a synthetic glucocorticoid) suppressed BDNF-induced glutamate release via weakening the activation of the PLC-γ (phospholipase C-γ)/Ca
2+
system in cultured cortical neurons. We demonstrated that the GR (glucocorticoid receptor) interacts with receptor tyrosine kinase for BDNF (TrkB). Following DEX treatment, TrkB-GR interaction was reduced due to the decline in GR expression. Corticosterone, a natural glucocorticoid, also reduced TrkB-GR interaction, BDNF-stimulated PLC-γ, and BDNF-triggered glutamate release. Interestingly, BDNF-dependent binding of PLC-γ to TrkB was diminished by DEX. SiRNA transfection to induce a decrease in endogenous GR mimicked the inhibitory action of DEX. Conversely, DEX-inhibited BDNF-activated PLC-γ signaling for glutamate release was recovered by GR overexpression. We propose that TrkB-GR interaction plays a critical role in the BDNF-stimulated PLC-γ pathway, which is required for glutamate release, and the decrease in TrkB-GR interaction caused by chronic exposure to glucocorticoids results in the suppression of BDNF-mediated neurotransmitter release via a glutamate transporter.
Regulatory effects of ferritin on angiogenesis
Authors: Coffman Lan G. , Parsonage Derek , D'Agostino Ralph , Torti Frank M. , Torti Suzy V.
Published: January 2009

Angiogenesis, the synthesis of new blood vessels from preexisting vessels, plays a critical role in normal wound healing and tumor growth. HKa (cleaved high molecular weight kininogen) is an endogenous inhibitor of angiogenesis formed by the cleavage of kininogen on endothelial cells. Ferritin is a protein principally known for its central role in iron storage. Here, we demonstrate that ferritin binds to HKa with high affinity (
K
d
13 nM). Further, ferritin antagonizes the antiangiogenic effects of HKa, enhancing the migration, assembly, and survival of HKa-treated endothelial cells. Effects of ferritin were independent of its iron content. Peptide mapping revealed that ferritin binds to a 22-aa subdomain of HKa that is critical to its antiangiogenic activity. In vivo, ferritin opposed HKa's antiangiogenic effects in a human prostate cancer xenograft, restoring tumor-dependent vessel growth. Ferritin-mediated regulation of angiogenesis represents a new angiogenic regulatory pathway, and identifies a new role for ferritin in cell biology.
Economic constraints to effective livestock waste management and policy implications.
Authors: Osei E. , Keplinger K. O.
Published: January 2009

Livestock operations contribute significantly to the agricultural output of many developed and developing nations. Over the past several decades, increased concentration of livestock farms, particularly in the USA, Europe, Canada and Australia, has spurred greater concern over the environmental implications of animal feeding operations. Manure generated as a by-product of livestock production has been linked to water and air pollution problems in many watersheds around the world. Location of confined livestock operations in close proximity to urban areas has also had impacts on nearby residential property values. Practices designed to reduce adverse environmental impacts of manure production and handling show varying degrees of promise. However, the usefulness of these practices is limited in some areas by various economic constraints such as cost to livestock operations, lack of adequate land for crop utilization of manure nutrients, and lack of incentives to promote uses of manure that are beneficial both from an environmental standpoint and from the farmer's point of view. This paper presents a review of the literature with an emphasis on the economic constraints livestock producers face in relation to manure management and how effective policies can be designed to encourage adoption of cost-effective livestock waste handling practices.
Modelling herbage utilization.
Authors: Holden N. M. , Brereton A. J.
Published: January 2009

This review addresses models associated with the utilization of herbage by grazing animals. Animal products from grazed herbage are economically and socially important throughout the world. The review focuses on the role of modelling at farm level and provides a broad picture of herbage utilization while focusing on grazing, with the objective of assessing how modelling contributes to increasing the efficiency of livestock production in systems where herbage utilization is the principal source of feed. Systems of production can vary widely according to climate, soil and social conditions, yet the review does not attempt to deal with all possible systems of herbage utilization, rather the focus is on livestock production in temperate climates. In this regard, the scope might be considered somewhat restricted, but it still presents a general assessment that is relevant to a wide range of circumstances. By focusing on the grazing component, the review addresses neither the mechanical harvesting of herbage as silage or hay, nor the environmental aspects of livestock systems that have become very important in recent years. These subjects constitute major areas of investigation in themselves and should be reviewed separately.
The use of acidifiers in fish nutrition.
Authors: Lückstädt C.
Published: January 2009

It is well established in the field of aquaculture that the use of antibiotic growth promoters (AGPs) as feed additives in the diets of fish and shrimp can improve live weight gain (LWG), feed conversion ratio (FCR) and survival rates. However, scientific knowledge and public concerns, especially in the EU, over the development of cross-resistance to antibiotics of importance to human health have led to a ban or a reduction in the use of such substances worldwide. Consequently, the aquafeed industry has turned its research attention to other additives in order to maintain performance and high survival rates in aquaculture. This review shows that acidifiers are an example of a group of additives which can play an important role in future in aquaculture diets. A number of studies, in cold-water and tropical species, indicate that a broad range of organic acids, their salts or admixtures can improve growth, feed utilization and disease resistance in fish.
Recent advancements in the management of pain in cats and dogs.
Authors: Robertson S. A.
Published: January 2009

Dogs and cats are popular pets and it is estimated that over one-third of households in the USA own a cat or dog, with an estimated national population of approximately 72 million dogs and 83 million cats. Many of these animals will undergo a surgical procedure such as an ovariohysterectomy or castration and because pets are living longer, chronic pain, for example that related to osteoarthritis, is of concern in senior animals. The number of published papers related to the recognition and treatment of pain in cats and dogs continues to grow exponentially; this is encouraging for those involved in small animal practice but keeping abreast of new developments can be a challenge. This review aims to discuss the value of current methods and to highlight new and emerging ideas in pain management for cats and dogs. Key topics include the physiology and pathobiology of pain, behaviour-based assessment of pain, the importance of pre-emptive treatment, the differences in the pharmacokinetics of drugs between cats and dogs and the place of complementary modalities such as acupuncture in veterinary pain management.
Mechanisms of cross-protection.
Authors: Ziebell H.
Published: January 2009

Cross-protection is a phenomenon in which mild or attenuated strains of a virus protect plants against secondary infections with a more severe strain of the same virus. Though this phenomenon was described in the 1920s, the mechanism(s) behind it have been poorly understood for many years. This review gives an historic overview of the discovery of cross-protection and the hypotheses that were initially put forward to explain the phenomenon. The involvement of the viral coat proteins (CPs) in the mechanism of cross-protection as well as the involvement of RNA silencing (thought to have evolved as an antiviral defence response of plants) are discussed. The author comes to the conclusion that in some cases cross-protection appears to require the CP of protective strains to prevent successful infection with a challenging strain but that in other cases cross-protection may operate either by highly localized RNA silencing or direct competition between strains for host cell resources.
Effects of climate change on horticultural plants and horticultural practices in Hungary.
Authors: Varga Z. , Varga-Haszonits Z.
Published: January 2009

Probable effects of climate change on Hungarian horticulture and possible responses to those effects are summarized in this review. The importance of these questions is emphasized by the complexity of the relationship between climate and horticultural crops. Horticultural production is influenced by climate in the following ways: * climate is an important part of local environmental conditions; * it is a system of driving environmental factors: climate permanently influences vital processes of plants; and * it is a system of risk factors: horticultural plants can suffer significant damage caused by extreme meteorological events. Climate change is a realistic possibility nowadays, but there are a lot of open questions concerning the scenarios. An essential element of uncertainty in research concerning climate change is the lack of precise definition of the difference between climatic variability and climate change. This is one of the fundamental reasons why the risk associated with the current warming tendency is a hotly debated question. However, there is no question that (quite apart from the different interpretations of anomalies) climate change is an environmental problem of great importance and a societal response cannot be delayed because of any uncertainties. The response includes mitigation of greenhouse gas concentration and assessment of expected changes as well as their effects, which may help adaptation. There is no generally accepted prescription for adaptation. Climate change occurs locally, and the changes could be entirely different in different regions of the Earth. In addition, the impacts of changes on horticultural crops depend on species, varieties and strains. Nevertheless, exchange of different experiences among regions and countries may be useful, because it can help local efforts of adaptation. Hungarian horticultural production probably would be more influenced by more frequent extreme meteorological conditions than by rising temperature. This tendency seems to be basically unfavourable. Whereas a warmer climate may even exert a beneficial effect on harvest prospects, extreme weather events will decrease yields. For this reason, crop security would become the prime focus of the horticultural sector.
Functional foods and natural health products: a review of consumer acceptance and regulatory issues.
Authors: Blandon J. , Henson S. , Cranfield J.
Published: January 2009

In recent years, consumer interest in functional foods and natural health products (NHPs) has increased considerably in industrialized countries, offering an opportunity for the agri-food sector to add value to agricultural commodities. At the same time, functional foods and NHPs offer potential health benefits that could enhance well-being of consumers and reduce the economic and social costs of non-communicable diseases. A critical issue mitigating the commercialization of functional foods and NHPs is consumer acceptance. Thus, there is a growing body of research on the attitudes of consumers towards functional foods and NHPs and their propensity of purchasing these products. This review provides a report of this research and suggests avenues for future research efforts. The functional food and NHP market has been highly dynamic over the last 10 years or so, with significant growth in the value of sales and in the number and variety of products. USA is the leading global market, followed by Europe and Japan. Both across and within these markets there is great variation in the attitudes of consumers towards functional foods and NHPs. These attitudes are influenced by a plethora of factors associated with the product themselves, consumer demographics and psychographics, policy and market context, etc. At the same time, distinct regulatory regimes act to differentiate markets and set the parameters in which consumers make their choices and the industry promotes their products.
Old and new facts of probiotics: where we are and where we are going.
Authors: Mayo B. , Delgado S. , Rodríguez J. M. , Gueimonde M.
Published: January 2009

Probiotics are live micro-organisms that when administered in adequate amounts confer a health benefit to the host. Though the majority of the micro-organisms used for this purpose belong to the
Lactobacillus
and
Bifidobacterium
genera, strains of many other bacterial and fungi species are currently being used as probiotics. Although not universally accepted, a consensus exists on the properties that probiotic micro-organisms present and the methodology used to assess their efficacy and safety. Scientific evidence recognizing that probiotics can play important roles in immunological, digestive and respiratory functions and could have significant effects in alleviating infectious disease symptoms is accumulating. However, fundamental knowledge relating to the exact mechanisms by which probiotics contribute to host health and well-being is still scarce. After a general introduction, this review will address old and new facts of probiotics, as well as relevant topics on which research interest should focus in the near future. This includes the search for more capable and robust strains of human origin with new (specific) properties, including those able to withstand the technological demands, the prevention and treatment of unique diseases and disorders, and, more importantly, the unequivocal substantiation of their claimed beneficial effects through controlled clinical trials.
Male sterility systems for hybrid seed production in
Brassica
crops.
Authors: Li XiuQing Li XiuQing
Published: January 2009

Brassica
crops are important sources of edible oil, leafy vegetables and renewable energy. In addition, some
Brassica
crops inhibit potato pests and have the potential to become cash crops from the potato rotation land for potato growers, if these crops yield well. One effective approach to increase
Brassica
crop productivity per unit land is through the use of the heterosis in hybrids prepared with male sterility systems. In
Brassica
crops, various male sterility systems have been identified or developed, including endogenous nuclear male sterility (NMS: recessive NMS, dominant NMS, interactive NMS), cytoplasmic male sterility (CMS: endogenous CMS, alloplasmic CMS) and transgenic male sterility. Both environmentally stable and sensitive male sterility systems are available and in use. The chlorosis associated with allochloroplasts in several alloplasmic CMS systems has been largely eliminated by organelle-selective protoplast fusion. Several mitochondrial CMS genes and a CMS fertility restorer gene (
Rfo
) have been identified and sequenced. The cloning of NMS genes and additional CMS fertility restorer genes is underway. The difficulty in maintaining NMS uniformity in populations has been partly solved by the interactive NMS (INMS)-based approach (epistatic suppressors for either recessive or dominant male sterility genes). INMS has become one of the most useful MS systems. This critical review focuses on the types, genetic analysis and technological breakthroughs of
Brassica
plant male sterility systems for their use in the large-scale hybrid-seed production.
The economics of food risk communication.
Authors: Ragona M. , Mazzocchi M.
Published: January 2009

With the emergence of major food scares throughout the world and their wide impact on the food sector, there has been a growing focus on the perils of bad risk communication. Scientific research has especially targeted on the psychological and sociological issues surrounding risk communication, but the economics literature also provides a theoretical and empirical basis for understanding consumer response and improving messages. This review aims at linking the various research streams, with an emphasis on the economic foundation. The range of issues is well beyond the gap between subjective and objective risk, and economics can often explain why communication fails to be effective in particular circumstances. A key but underinvestigated area is the communication of uncertainty, where economics can provide a useful background.
Recent developments in the diagnosis and therapy of repeat breeding cows and buffaloes.
Authors: Purohit G. N.
Published: January 2009

Repeat breeding (RB) continues to be a big problem for breeders and veterinary clinicians. A brief mention is made of the common aetiological and risk factors for RB in cattle and buffaloes, and the possible diagnostic and therapeutic approaches are described in detail. Important diagnostic tools could include rectogenital palpation, vaginoscopy, uterine cytology and the
in vivo
imaging technique of ultrasonography. When considering the most common causes of RB, vaginoscopy and palpation continue to be the only diagnostic tools available to clinicians at many locations, while by using ultrasonography, diagnostic accuracy can be increased markedly, especially when dealing with individual cows or buffaloes. Contrarily, when dealing with herds, metabolic profiles and sampling to detect infectious disease must be the clinicians' choice. Of pertinent consideration are the management regimens and feeding practices. Despite the development of many diagnostic procedures such as hormone assays, colour Doppler sonography, and hysteroscopy, diagnosing the cause of pregnancy failure in an individual cow/buffalo continues to be difficult, as a proportion of animals demonstrate obscure infertility. The choice of a therapeutic regimen depends on the possible cause of RB. Recent advances in the therapy of endometritis include the use of immunomodulators such as
Escherichia coli
lipopolysaccharide, use of eicosanoid PGF
2
α and therapy with enzymes with or without therapy with antibiotics, the use of which continues to be debatable. The therapy of ovulation induction in various ovulatory disturbances includes regimens utilizing hCG, GnRH, prostaglandins and their combinations. It appears that RB animals with aberrations of oestrus cycle do demonstrate such ovulation asynchronies. Suprabasal progesterone concentration at oestrus is thought to be an important contributor of RB, but remediation of this is largely unknown although reducing stress appears to be a probable method. Luteal insufficiency can be resolved by administration of hCG and GnRH or progestagens. A brief mention is made of ways of improving management and insemination procedures.