bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of vapor transport equilibration on the crystal quality and thermal-expansion coefficients of γ-LiAlO2
Authors: Zou Jun , Zhou Shengming , Xu Jun , Zhang Lianhan , Xie Zili , Han Ping , Zhang Rong
Published: October 2005

γ - Li Al O 2 (LAO) single crystal has been grown by the Czochralski method. However, its quality was deteriorated due to lithium volatilization during the crystal growth. The full width at half maximum value drops from 116.9to44.2arcsec after the LAO slice was treated by vapor transport equilibration at 1000, 1100, and 1200°C∕48h in sequence. The treated slice shows higher optical transmission than the as-grown one in the measured wavelength range of 190–1900nm, meanwhile, its absorption edge exhibits a blueshift. According to Raman spectra, the treated slice has homogeneous quality at different depths from surface to 0.01mm. The expansion coefficient of the treated slice for a axis drops from 17.2398×10−6∕°Cto16.5240×10−6∕°C, and that for c axis drops from 10.7664×10−6∕°Cto10.0786×10−6∕°C.
Study of laser-induced self-oscillations in silicon nanomechanical resonators
Authors: Li Jingjing , Evoy S.
Published: October 2005

We report a study of laser-induced oscillation of nanomechanical resonators. The modes of motion of single-stage and double-stage paddle resonators are first assessed using finite element analysis and experimentally observed using piezoelectric actuation of the devices. The flexural modes of the same devices are then excited at resonance using laser-induced thermal effects. As the actuating power is gradually increased, the resonators experience three phases of resonance characterized by distinct changes of amplitude and number of peaks observed. In addition, the resonant frequencies initially show a steady decrease with actuating power followed by a distinct increase. Finally, a sharpening of the resonant response is also observed as actuating power is increased. However, such peak sharpening is also accompanied by instabilities of the center frequency. These instabilities could be induced by a frequency mismatch between the parametric actuation mechanism and the natural resonance of the device, or by optically induced temperature fluctuations along the length of the resonator supports.
Growth-parameters-dependent magnetoresistance in pulsed-laser-deposited (La0.5Pr0.2)Ba0.3MnO3 thin films
Authors: Mavani K. R. , Rana D. S. , Malik S. K. , Markna J. H. , Parmar R. N. , Kuberkar D. G. , Misra P. , Kukreja L. M. , Kundaliya D. C.
Published: October 2005

Epitaxial thin films of (La0.5Pr0.2)Ba0.3MnO3 were deposited on LaAlO3 single-crystal substrates using pulsed laser deposition (PLD) technique with different growth parameters. Structural, surface morphological, electrical, and magnetotransport measurements on these films revealed that unoptimized growth parameters during the deposition using the third harmonic of a Q-switched Nd: YAG laser yielded structurally inhomogeneous epitaxial films having a columnar morphology, while the optimized growth parameters using an excimer laser during the PLD resulted in homogeneous epitaxial films with a smooth morphology. Interestingly, at a temperature of 5K, the films with unoptimized growth parameters showed a large high-field magnetoresistance (MR) of ∼90% while the films with optimized growth parameters showed a high-field MR of only ∼15%. It is contemplated that this exceptionally large MR in the unoptimized films might be due to the phase separation and coexistence of metallic and insulating phases.
Do organic solutes experience specific interactions with ionic liquids?
Authors: Mali K. S. , Dutt G. B. , Mukherjee T.
Published: October 2005

In an attempt to understand the nature of interactions between organic solutes and room temperature ionic liquids, temperature-dependent rotational relaxation of two structurally similar nondipolar solutes—2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP)—has been examined in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim+][PF6−]). Even with the ionic liquid, where the cation and the anion are strongly associated, the solute DPP experiences specific interactions, which is evident from its reorientation times that are 50%-60% longer in relation to DMDPP. It has been noticed that the reorientation times of both the solutes are faster in [bmim+][PF6−] than in glycerol, which is also a strongly associated solvent and whose viscosity is similar to the ionic liquid. This observation has been explained by taking into consideration the relative sizes of the solvents. By comparing the ratios of the reorientation times of DPP to DMDPP, in [bmim+][PF6−] and glycerol, it has been deduced that the strengths of the interaction between DPP—[bmim+][PF6−] and DPP—glycerol are the same.
Electrolytes at spherical dielectric interfaces
Authors: Curtis R. A. , Lue L.
Published: October 2005

A variational theory is developed and applied to study the properties of dielectric spheres immersed in a symmetric electrolyte solution. In the limit that the radius of the sphere becomes much larger than the Debye screening length, the system reduces to that of a planar dielectric interface. For this case, the excess surface tension obtained by the variational theory reduces to the Onsager-Samaras [J. Chem. Phys. 2, 528 (1934)] limiting law at low electrolyte concentrations. As the radius of the dielectric sphere decreases, the excess surface tension also decreases. The implications of this work to protein-salt interactions and the salting out of proteins are discussed.
Three-isotope plot of fractionation in photolysis: A perturbation theoretical expression
Authors: Prakash M. K. , Marcus R. A.
Published: October 2005

The slope of the three-isotope plot for the isotopomer fractionation by direct or nearly direct photodissociation is obtained using a perturbation theoretical analysis. This result, correct to first order in the mass difference, is the same as that for equilibrium chemical exchange reactions, a similarity unexpected a priori. A comparison is made with computational results for N2O photodissociation. This theoretical slope for mass-dependent photolytic fractionation can be used to analyze the data for isotopic anomalies in spin-allowed photodissociation reactions. Earlier work on chemical equilibria is extended by avoiding a high-temperature approximation.
Femtosecond pulse compression using the Z-scan technique and closed-loop evolutionary algorithm
Authors: Silva D. L. , Guedes I. , Zilio S. C. , Misoguti L. , Mendonça C. R.
Published: October 2005

We present a method that uses the Z-scan signal as a feedback in the femtosecond-pulse-shaping apparatus for pulse compression employing a closed-loop evolutionary algorithm. This approach takes advantage of the Z-scan technique’s experimental simplicity and high sensitivity in the measurement of optical nonlinearities for obtaining transform-limited pulses. This was demonstrated by optimizing pulses from a Kerr-lens modelocked Ti:sapphire laser using the strong two-photon absorption process in the ZnSe sample, yielding a decrease in the pulse duration from 43to20fs and a phase correction compatible with that of Fourier-transformed pulses.
Propagation characteristics of the fundamental symmetric Lamb wave in thin aluminum nitride membranes with infinite gratings
Authors: Yantchev Ventsislav M. , Katardjiev Ilia V.
Published: October 2005

A theoretical approach for the analysis of Lamb waves in grating configurations based on the Floquet-Bloch theorem is developed. Subsequently, it is applied for the prediction of the propagation characteristics of the fundamental symmetric Lamb wave (S0) propagating in thin c-oriented aluminum nitride (AlN) membranes with different types of aluminum grating configurations. The calculations indicate the existence of a frequency stop band exhibiting a complex behavior. The proposed analysis is to be used for the design and optimization of high velocity thin-film Lamb wave resonators. It can easily be adapted for the analysis of arbitrary Lamb waves in periodic gratings.
Raman study on the stress state of [111] diamond anvils at multimegabar pressure
Authors: Akahama Yuichi , Kawamura Haruki
Published: October 2005

The first-order Raman spectra of diamond anvils with their loading axis along the [111] crystal direction have been measured at pressures up to 220 GPa, and the stress state at the center of the culet of the anvils was studied. Two steep edges were observed at the high-frequency side of the spectra under high pressure and attributed to the singlet-doublet splitting of the triply degenerated F2g optical-phonon band due to a uniaxial stress. The pressure dependence of the splitting exhibited a remarkable flattening above 100 GPa. From the stress state analysis, the ratio of the stress components of both σz (vertical stress) and σR (radial stress) with the shear stress τ=(σz−σR)∕2 on the culet of diamond anvils was estimated as a function of pressure. These results suggested that the increase in the shear stress τ with pressure was suppressed due to the enhancement of σR above 100 GPa, while τ reached 40 GPa at 220 GPa. The unexpectedly lower value of τ at multimegabar pressures compared with the predicted value of τmax=100GPa strongly suggested the possibility of a further extension of a feasible pressure, though the use of a [111] diamond anvil allowed us to generate a maximum pressure of 222 GPa.
Solitary perturbations of magnetic flux tubes
Authors: Stix M. , Zhugzhda Y. D. , Schlichenmaier R.
Published: October 2005

The thin-tube expansion in the two-mode approximation [Y. D. Zhugzhda, Phys. Plasmas 3, 10 (1996); 9, 971 (2002)] is applied to magnetic flux tubes. The propagation of finite-amplitude perturbations is studied numerically. A behavior is found that closely resembles solitary waves. In the two-mode approximation, the slow body wave possesses the dispersion that is needed to prevent shock formation. There is qualitative agreement with an analytic treatment of weakly nonlinear slow body waves [Y. D. Zhugzhda, Phys. Plasmas 11, 2256 (2004)] in which the problem was reduced to a new model equation.
Insights into the radiation response of pyrochlores from calculations of threshold displacement events
Authors: Devanathan R. , Weber W. J.
Published: October 2005

We have used molecular-dynamics simulations to examine the displacement threshold energy (Ed) surface for cations and anions in Gd2Ti2O7 and Gd2Zr2O7 pyrochlores. In both pyrochlores, the Ed surface is highly anisotropic and it requires less energy to displace anions than cations. Both anion and cation Ed values are higher in the titanate compared to the zirconate. Titanium displacement energies are in excess of 170eV for all directions examined, because cation exchange is less energetically favorable in Gd2Ti2O7 compared to Gd2Zr2O7. These high-energy Ti displacements result in the formation of defect clusters that may prevent efficient defect recovery. This provides an explanation for the difference in susceptibility to amorphization between titanate and zirconate pyrochlores.
Diffused ferroelectrics of Ba6Ti2Nb8O30 and Sr6Ti2Nb8O30 with filled tungsten-bronze structure
Authors: Yuan Y. , Chen X. M. , Wu Y. J.
Published: October 2005

We have synthesized ferroelectrics of M6Ti2Nb8O30 (M=Ba, Sr) with filled tungsten-bronze structure. The microstructures and dielectric properties of the present materials have been investigated as well as the behavior and features of the ferroelectric phase transition. Similar to perovskite ABO3, tungsten-bronze structure consists of several BO6 octahedra. The close distortion of BO6 octahedra concluded from the 10c∕a ratios is observed in Ba6Ti2Nb8O30 and Sr6Ti2Nb8O30, and two ferroelectrics have the close Curie temperature (155°C for the former and 160°C for the latter at 1MHz). Deducing from Raman spectra at different temperatures around phase transition and the modified Curie-Weiss law, the ferroelectric phase transition of Ba6Ti2Nb8O30 and Sr6Ti2Nb8O30 may belong to the displacive transition. The obvious diffuse characteristics of the ferroelectric transition may be attributed to the disordered distributions of octahedra, as two kinds of BO6, i.e., TiO6 and NbO6, exist in one cell. The weak ferroelectric of the present materials are indicated from the P-E hysteresis loops, both with 2Pr of 4μC∕cm2.
Efficient aminosilane adhesion promoter for soft nanoimprint on GaAs
Authors: Gallo Pascal , Viallet Benoît , Daran Emmanuelle , Fontaine Chantal
Published: October 2005

We present a surface treatment of GaAs for nanoimprint applications. This aminoethoxysilane adhesion promoter creates covalent bonds between the GaAs substrate and the polymer to be imprinted. The self-assembled layer has an optimised roughness of less than 1nm, which meets the requirements of sub-10nm features reproduction. Here, soft nanoimprint of 100nm features with a less than 10-nm-thick residual layer is presented.
Quantum interference effect in single Pt(Ga)∕C nanowire
Authors: Liao Z. M. , Xu J. , Song Y. P. , Zhang Y. , Xing Y. J. , Yu D. P.
Published: October 2005

The electron transport behavior in single Pt(Ga)∕C nanowire fabricated using focused ion beam was studied. The Pt(Ga)∕C nanowire consists of <3nm Pt particles, which are sheathed with Ga+-doped amorphous carbon layers. The temperature dependence of the nanowire resistivity measured under four-probe method indicated the weak localization effect resulting from large disorder in the system. Moreover, low temperature resistivity of the nanowire increased with decrease of its temperature, following a −T law, which could be interpreted by electron-electron interaction in weak localization regime. An anomalous positive magnetoresistance was observed as well, which was ascribed to quantum interference effect arising from Coulomb interactions and weak localization in the strong spin-orbit scattering limit.
Spectral-resolved microprobe cathodoluminescence investigations of Al-doped single-crystalline Ba0.6Sr0.4TiO3 thin films
Authors: Chen T. L. , Li X. M. , Wan K. S. , Zhu W. L. , Pezzotti G.
Published: October 2005

Single-crystalline Al-doped Ba0.6Sr0.4TiO3 (BST) thin films have been pulsed-laser deposited onto Ir∕MgO buffered Si substrates. Spectral-resolved microprobe cathodoluminescence measurements of Al-doped BST thin films at room temperature clearly showed three detectable luminescence bands in the wavelength range between 200 and 900 nm. We assigned the first shoulder peak to saturation of phonon-assisted processes, with a band gap transition resulting in the second sharp band. The band-maximum position of a third (defect-related) broad luminescence band varied with varying the concentration of Al dopant. By fitting this latter band as the sum of three superimposed Gaussian curves, it was revealed that the incorporation of Al dopant into the BST crystal lattice had a direct impact on the defect population existing in the single-crystalline film. For perovskite ABO3-structured BST thin films, it is suggested that the Al dopant occupies the B site (Ti) in a low range of dopant concentrations, while at higher dopant concentrations Al might occupy both A sites (Ba or Sr) and B sites.
Dynamics of a high-Q vertical-cavity organic laser
Authors: Koschorreck M. , Gehlhaar R. , Lyssenko V. G. , Swoboda M. , Hoffmann M. , Leo K.
Published: October 2005

We investigate the dynamics of the organic laser guest-host composite of tris-(8-hydroxy quinoline) aluminium and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran embedded in a high-Q (Q≈4500) double distributed Bragg reflector microcavity using subpicosecond up-conversion techniques. Lasing is observed at a threshold of 0.4nJ∕20μJcm−2 with a linewidth of 0.05 nm (resolution limit). We observe a strongly nonlinear intensity-dependent delay of the emitted radiation burst. All experimental results are successfully modeled by a set of nonlinear rate equations, emphasizing the importance of a feedback mechanism for lasing.
Observation of fragile-to-strong liquid transition in surface water in CeO2
Authors: Mamontov E.
Published: October 2005

A quasielastic neutron-scattering experiment carried out on a backscattering spectrometer with sub-μeV resolution in the temperature range of 200–250K has revealed the dynamics of surface water in cerium oxide on the time scale of hundreds of picoseconds. This slow dynamics is attributed to the translational mobility of the water molecules in contact with the surface hydroxyl groups. The relaxation function of this slow motion can be described by a slightly stretched exponential with the stretch factor exceeding 0.9, which indicates almost a Debye-type dynamics. Down to about 220K, the temperature dependence of the residence time for water molecules follows a Vogel-Fulcher-Tamman law with the glass transition temperature of 181K. At lower temperatures, the residence time behavior abruptly changes, indicating a fragile-to-strong liquid transition in surface water at about 215K.
Nitrogen doping and thermal stability in HfSiOxNy studied by photoemission and x-ray absorption spectroscopy
Authors: Toyoda Satoshi , Okabayashi Jun , Takahashi Haruhiko , Oshima Masaharu , Lee Dong-Ick , Sun Shiyu , Sun Steven , Pianetta Piero A. , Ando Takashi , Fukuda Seiichi
Published: October 2005

We have investigated nitrogen-doping effects into HfSiOx films on Si and their thermal stability using synchrotron-radiation photoemission and x-ray absorption spectroscopy. N1s core-level photoemission and NK-edge absorption spectra have revealed that chemical-bonding states of N–Si3−xOx and interstitial N2-gaslike features are clearly observed in as-grown HfSiOxNy film and they decrease upon ultrahigh vacuum (UHV) annealing due to a thermal instability, which can be related to the device performance. Annealing-temperature dependence in Hf4f and Si2p photoemission spectra suggests that the Hf-silicidation temperature is effectively increased by nitrogen doping into the HfSiOx although the interfacial SiO2 layer is selectively reduced. No change in valence-band spectra upon UHV annealing suggests that crystallization of the HfSiOxNy films is also hindered by nitrogen doping into the HfSiOx.
Photoluminescence spectroscopy of bandgap reduction in dilute InNAs alloys
Authors: Veal T. D. , Piper L. F. J. , Jefferson P. H. , Mahboob I. , McConville C. F. , Merrick M. , Hosea T. J. C. , Murdin B. N. , Hopkinson M.
Published: October 2005

Photoluminescence (PL) has been observed from dilute InNxAs1−x epilayers grown by molecular-beam epitaxy. The PL spectra unambiguously show band gap reduction with increasing N content. The variation of the PL spectra with temperature is indicative of carrier detrapping from localized to extended states as the temperature is increased. The redshift of the free exciton PL peak with increasing N content and temperature is reproduced by the band anticrossing model, implemented via a (5×5)k∙p Hamiltonian.
Enhancement of microarcing at a grounded chamber wall by nonvanishing ion sheath in a radio-frequency capacitive discharged plasma
Authors: Kwok Dixon T. K. , Yin Yongbai , Bilek Marcela M. M. , McKenzie David
Published: October 2005

One-dimensional hybrid particle-in-cell simulations in cylindrical r coordinate, with particle ions and Boltzmann’s distribution of electrons, are used to investigate the arcing effect in radio-frequency (rf) capacitively coupled discharged plasma. The simulation shows that the arcing at the chamber wall is enhanced by the nonvanishing ion sheath at the surface, such that the emission electrons current will last for several tens of rf cycles. On the other hand, at the inner electrode, the electron emission occurs only during certain phases of the rf cycle and does not promote arc growth.
Traps in AlGaN∕GaN∕SiC heterostructures studied by deep level transient spectroscopy
Authors: Fang Z.-Q. , Look D. C. , Kim D. H. , Adesida I.
Published: October 2005

AlGaN ∕ GaN ∕ SiC Schottky barrier diodes (SBDs), with and without Si3N4 passivation, have been characterized by temperature-dependent current-voltage and capacitance-voltage measurements, and deep level transient spectroscopy (DLTS). A dominant trap A1, with activation energy of 1.0 eV and apparent capture cross section of 2×10−12cm2, has been observed in both unpassivated and passivated SBDs. Based on the well-known logarithmic dependence of DLTS peak height with filling pulse width for a line-defect related trap, A1, which is commonly observed in thin GaN layers grown by various techniques, is believed to be associated with threading dislocations. At high temperatures, the DLTS signal sometimes becomes negative, likely due to an artificial surface-state effect.
Field emission from carbon layers containing very long and sparse nanotubes∕nanofilaments
Authors: Musatov A. L. , Izrael’yants K. R. , Ormont A. B. , Krestinin A. V. , Kiselev N. A. , Artemov V. V. , Zhigalina O. M. , Grigoriev Yu. V.
Published: October 2005

Field-emission characteristics of carbon layers with very long (up to several mm) and sparse nanotubes (nanofilaments) have been investigated. For such layers field emission current of 10μA is registered at very low average electric field Eav=0.16V∕μm and the values of the field amplification coefficient β reach 45 000. It has been found that, at electric fields corresponding to the onset of the field emission, the emitting nanotubes are stretched towards the anode. At high emission currents (exceeding 30–50μA), one or several luminous filaments have been observed in the gap between the sample and the anode. These luminous filaments are carbon nanotubes (nanofilaments) heated by the emission current.
Induction of embryo development and fixation of partial interspecific lines after pollination of F1 cotton interspecific hybrids (Gossypium barbadense × Gossypium hirsutum) with pollen from Hibiscus cannabinus
Authors: Mavromatis A. G. , Kantartzi S. K. , Vlachostergios D. N. , Xynias I. N. , Skarakis G. N. , Roupakias D. G.
Published: October 2005

The possibility of inducing embryo development after pollination of F1 interspecific cotton hybrids (Gossypium barbadense × Gossypium hirsutum) and their reciprocals with pollen from Hibiscus cannabinus was investigated. For this, flowers of F1 plants from 4 G. barbadense × G. hirsutum interspecific hybrids (B403 × Acala Sindos, Carnak × 4S, B403 × Coker 310, and Carnak × Acala Sindos) and their reciprocals grown in the field were pollinated with pollen from Hibiscus cannabinus. From the 443 pollinated flowers, 276 were left on the plant to grow naturally, and 167 were collected 5 days after pollination. Young ovules from the collected buds were cultured in vitro for embryo development. It was observed that, from the buds left to grow naturally on the mother plant, 21 bolls reached maturity. The mature bolls originated only from the 4 G. barbadense × G. hirsutum hybrids and contained 82 mature seeds. Finally, 38 plants (Pa0) were produced. From the in-ovule culture method, 10 young embryos were isolated from both G. barbadense × G. hirsutum and G. hirsutum × G. barbadense hybrids and finally 3 plants were produced. The plants produced from both approaches originated only from the G. barbadense × G. hirsutum hybrids. These plants exhibited morphological traits from both cotton species and they were partially fertile. No signs of H. cannabinus morphological traits were observed in the plants produced. Root-tip chromosome counts revealed that chromosome number among cells of the Pa0 plants ranged from 27 to 42 and the difference in chromosome number observed among cells of the same plant ranged from 1 to 3. The chromosome number, however, was increased progressively from generation to generation and in Pa3 it ranged from 46 to 52. Plants with 52 chromosomes were identified even from the Pa1 generation. In addition, flow cytometric analysis indicated that the parental plants had a similar DNA profile to the F1 and F2 interspecific hybrids but a different one from the Pa0 plants. Thus, alien pollination of cotton flowers from interspecific (G. barbadense × G. hirsutum and reciprocals) hybrids with pollen from H. cannabinus most likely induced parthenogenetic (Pa) egg cell development which, after a progressive chromosome increase, produced fully fertile plants with most of the cells at the tetraploid or near-tetraploid level. It was concluded that a combination of the in situ boll development with an optimised in vitro ovule culture technique could establish the ‘cannabinus method’ in cotton, as a method for the production of genotype-independent partial interspecific lines.
Genetic variation in populations of Western Australian wild radish
Authors: Madhou P. , Wells A. , Pang E. C. K. , Stevenson T. W.
Published: October 2005

Raphanus raphanistrum L. (wild radish) is a major problematic weed worldwide. Random amplified polymorphic DNA (RAPD) was used to estimate the degree of genetic diversity between and within 2 populations of wild radish (WARR 5 and WARR 6), found to exhibit multiple herbicide resistance compared with a susceptible population (WARR 7). It is believed that weed species with high degrees of genetic variation show potential for developing resistance to herbicides. Of the 13 RAPD primers screened, 9 primers generated 97 polymorphic bands concomitant with a high level of polymorphism (82%) between the wild radish populations, characteristics of an outbreeding species. Analysis of molecular variance (AMOVA) showed a markedly higher proportion of diversity within populations (87%) as opposed to between populations (13%). Principal component analysis (PCA) further highlighted the large amount of variation between individuals within populations. Only one marker, OPC19–8, was found to be unique to the WARR 7 population but absent in WARR 5 and in most individuals of the WARR 6 populations. This marker may potentially be correlated with herbicide susceptibility. The 2 resistant wild radish populations were found to be closely related (0.7% dissimilar) to each other, whereas the susceptible population was genetically dissimilar to them by 2.3%. This higher level of dissimilarity between the susceptible and resistant populations may be explained by limited gene flow between them since the susceptible population is geographically located further away from the resistant populations. Hence, it may be concluded that the underlying genetic structure of the 3 wild radish populations seems to be similar despite WARR 6 and WARR 5 having been exposed to mixed herbicide usage for over 17 years.
New Trifolium subterraneum genotypes identified with resistance to race 2 of Kabatiella caulivora and cross-resistance to fungal root rot pathogens
Authors: You M. P. , Barbetti M. J. , Nichols P. G. H.
Published: October 2005

One hundred subterranean clover genotypes including 72 advanced breeding lines from Trifolium subterraneum ssp. subterraneum and Trifolium subterraneum ssp. yanninicum and 28 Trifolium subterraneum commercial cultivars were screened in the field for resistance to race 2 of Kabatiella caulivora, and the resistances found were related to known resistance to major root pathogens in the region. Race 2 of K. caulivora causes severe damage on subterranean clover in the south-eastern coastal region of Western Australia and 72 of the 100 genotypes tested were resistant to this race, with levels similar to those shown by the cultivar Denmark. The unique importance of this study was that, for 12 genotypes of subterranean clover, these resistances were related to those shown to major root pathogens, viz. one or more of Phytophthora clandestina, Pythium irregulare, and Fusarium avenaceum. Availability of genotypes with such resistances to multiple pathogens is expected to be particularly valuable for the breeding/selection of subterranean clover in relation to the development of new cultivars with effective resistance to a range of pathogens that commonly occur in southern Australian annual legume pastures.
Australian wheat for the sponge and dough bread making process
Authors: Lever T. , Kelly A. , De Faveri J. , Martin D. , Sheppard J. , Quail K. , Miskelly D.
Published: October 2005

This work investigates the suitability of Australian wheats for the sponge and dough bread market, and determines the wheat quality attributes most important for large loaf volume. A group of 30 genotypes was selected for quality testing and baking using a purpose-developed sponge and dough test baking method. Genotypes were grown at 2 sites in Queensland during winter of 2001 and 2002, and then grain from the field trials was tested in the laboratory. The traits measured included grain, flour, and dough quality, along with loaf volume as the main trait of interest. Glutenin alleles and Wx-B1 allele status of the genotypes were also determined. Genetic correlations were calculated between loaf volume and all the quality traits. The quality trait with the strongest relationship to loaf volume was flour swelling volume. Glutenin alleles and Wx-B1 alleles may also be important for sponge and dough bread quality but the data presented here were insufficient to draw strong conclusions. Consistent, large sponge and dough loaf volumes (>850 cm3) were achieved by the Batavia/Pelsart double haploids QT8753, QT10793, and QT10778. The wheat varieties Hartog and Kennedy also performed well. The work demonstrated that Australia can produce wheat suitable for this market.
Hexose uptake by developing cotyledons of Vicia faba: physiological evidence for transporters of differing affinities and specificities
Authors: Harrington Gregory N. , Dibley Katherine E. , Ritchie Raymond J. , Offler Christina E. , Patrick John W.
Published: October 2005

Cotyledons of broad bean (Vicia faba L.) develop in an apoplasmic environment that shifts in composition from one dominated by hexoses to one dominated by sucrose. During the latter phase of development, sucrose / H+ symporter activity and expression is restricted to cotyledon epidermal transfer cell complexes that support sucrose fluxes that are 8.5-fold higher than those exhibited by the storage parenchyma. In contrast, the flux difference between these cotyledon tissues is only 1.7-fold for hexoses. Glucose and fructose uptake was shown to be sensitive to PCMBS and phloridzin, both of which slow H+-sugar transport. A low Km (or high affinity transporter, HAT) mechanism transports glucose and glucose-analogues exclusively. No HAT system for fructose could be found. A high Km (low affinity transporter, LAT) mechanism transports a broader range of hexoses, including glucose and fructose. Consistent with glucose and fructose transport being H+-coupled, their uptake was inhibited by dissipating the proton motive force (pmf) by treating cotyledons with carbonyl cyanide m-chlorophenol hydrazone, propionic acid or tetraphenylphosphonium ion. Erythrosin B inhibited hexose uptake, indicating a role for the P-type H+-ATPase in establishing the pmf. It is concluded that H+-coupled glucose and fructose transport mechanisms occur at plasma membranes of dermal transfer cell complexes and storage parenchyma cells. These transport mechanisms are active during pre- and storage phases of cotyledon development. However, hexose symport only makes a quantitative contribution to cotyledon biomass gain during the pre-storage stage of development.
Revision of Myrsine (Myrsinaceae) in Australia
Authors: Jackes Betsy R.
Published: October 2005

The genus Myrsine L., has been revised for Australia. The broader circumscription of the genus including Rapanea Aubl., has been followed. Twenty species are described, including twelve new species: Myrsine arenaria Jackes, M. angusta Jackes, M. elata Jackes, M. ireneae Jackes, M. kimberleyensis Jackes, M. maculata Jackes, M. oreophila Jackes, M. pedicellata Jackes, M. richmondensis Jackes, M. rubiginosa Jackes, M. serpenticola Jackes, M. smithii Jackes. One new combination is made, Myrsine howittiana (F. Muell. ex Mez) Jackes. Four species M. howittiana (F. Muell. ex Mez) Jackes, M. porosa F. Muell., M. variabilis R.Br., and M. subsessilis F. Muell., are lectotypified. New subspecies described are M. ireneae subsp. curvata and M. subsessilis subsp. cryptostemon. All appropriate combinations have been made for Australian mainland species as well as for species occurring on Lord Howe and Norfolk Islands. A key to the species is provided. The main character states are discussed, particularly the nature of the trichomes, the glands or secretory structures, and aspects of the inflorescence and the flowers.
A revision of Cassinia (Asteraceae: Gnaphalieae) in Australia. 4. Section Costatae
Authors: Orchard A. E.
Published: October 2005

The species of Cassinia sect. Costatae are keyed, described and illustrated. New taxa described are Cassinia lepschii, C. heleniae, C. wyberbensis, C. ochracea and C. nivalis.
Generic concepts in Styphelieae (Ericaceae): the Cyathodes group
Authors: Quinn Christopher J. , Brown Elizabeth A. , Heslewood Margaret M. , Crayn Darren M.
Published: October 2005

Non-molecular and atpB−rbcL spacer sequence datasets for 38 taxa representing Cyathodes Labill. sensu lato and its relatives, together with several outgroups from Styphelieae, Oligarrheneae, Epacreae and Archerieae, were subjected to cladistic analyses. The monophyly of Cyathodes sensu Weiller, Leptecophylla Weiller, Lissanthe R.Br. sensu Crayn et al. and Planocarpa Weiller is supported. Cyathopsis Brongn. & Gris is expanded to include two other New Caledonian species, Styphelia violaceospicata (Guillaumin) McPherson and S. albicans (Brongn. & Gris) Sleumer. Androstoma Hook.f. is redefined to include Leucopogon milliganii (F.Muell.) Rodway. Leucopogon durus Benth. is transferred to Acrotriche R.Br. Two new genera are described: Acrothamnus C.J.Quinn, comprising at least five species in eastern Australia, New Zealand, New Guinea and the Pacific; Agiortia C.J.Quinn, comprising three species in north-eastern New South Wales and south-eastern Queensland. Keys to the species of Acrothamnus, Agiortia, Androstoma and Cyathopsis are provided.
Creating oral squamous cancer cells: A cellular model of oral–esophageal carcinogenesis
Authors: Goessel Gitta , Quante Michael , Hahn William C. , Harada Hideki , Heeg Steffen , Suliman Yasir , Doebele Michaela , von Werder Alexander , Fulda Christine , Nakagawa Hiroshi , Rustgi Anil K. , Blum Hubert E. , Opitz Oliver G.
Published: October 2005

Immortalization and malignant transformation are important steps in tumor development. The ability to induce these processes from normal human epithelial cells with genetic alterations frequently found in the corresponding human cancer would significantly enhance our understanding of tumor development. Alterations in several key intracellular regulatory pathways (the pRB, p53, and mitogenic signaling pathways and the telomere maintenance system) appear to be sufficient for the neoplastic transformation of normal human cells. Nevertheless,
in vitro
transformation models to date depend on viral oncogenes, most prominently the simian virus 40 early region, to induce immortalization and malignant transformation of normal human epithelial cells. Here, we demonstrate a transformation model creating oral–esophageal cancer cells by using a limited set of genetic alterations frequently observed in the corresponding human cancer. In a stepwise model, cyclin D1 overexpression and p53 inactivation led to immortalization of oral keratinocytes. Additional ectopic epithelial growth factor receptor overexpression followed by c-myc overexpression as well as consecutive reactivation of telomerase induced by epithelial growth factor receptor sufficed to transform oral epithelial cells, truly recapitulating the development of the corresponding human disease.
Inhibition of colony-stimulating-factor-1 signalingin vivowith the orally bioavailable cFMS kinase inhibitor GW2580
Authors: Conway James G. , McDonald Brad , Parham Janet , Keith Barry , Rusnak David W. , Shaw Eva , Jansen Marilyn , Lin Peiyuan , Payne Alan , Crosby Renae M. , Johnson Jennifer H. , Frick Lloyd , Lin Min-Hwa Jasmine , Depee Scott , Tadepalli Sarva , Votta Bart , James Ian , Fuller Karen , Chambers Timothy J. , Kull Frederick C. , Chamberlain Stanley D. , Hutchins Jeff T.
Published: October 2005

Colony-stimulating-factor-1 (CSF-1) signaling through cFMS receptor kinase is increased in several diseases. To help investigate the role of cFMS kinase in disease, we identified GW2580, an orally bioavailable inhibitor of cFMS kinase. GW2580 completely inhibited human cFMS kinasein vitroat 0.06 μM and was inactive against 26 other kinases. GW2580 at 1 μM completely inhibited CSF-1-induced growth of mouse M-NFS-60 myeloid cells and human monocytes and completely inhibited bone degradation in cultures of human osteoclasts, rat calvaria, and rat fetal long bone. In contrast, GW2580 did not affect the growth of mouse NS0 lymphoblastoid cells, human endothelial cells, human fibroblasts, or five human tumor cell lines. GW2580 also did not affect lipopolysaccharide (LPS)-induced TNF, IL-6, and prostaglandin E2 production in freshly isolated human monocytes and mouse macrophages. After oral administration, GW2580 blocked the ability of exogenous CSF-1 to increase LPS-induced IL-6 production in mice, inhibited the growth of CSF-1-dependent M-NFS-60 tumor cells in the peritoneal cavity, and diminished the accumulation of macrophages in the peritoneal cavity after thioglycolate injection. Unexpectedly, GW2580 inhibited LPS-induced TNF production in mice, in contrast to effects on monocytes and macrophagesin vitro. In conclusion, GW2580's selective inhibition of monocyte growth and bone degradation is consistent with cFMS kinase inhibition. The ability of GW2580 to chronically inhibit CSF-1 signaling through cFMS kinase in normal and tumor cellsin vivomakes GW2580 a useful tool in assessing the role of cFMS kinase in normal and disease processes.
Simulating movement of tRNA into the ribosome during decoding
Authors: Sanbonmatsu Kevin Y. , Joseph Simpson , Tung Chang-Shung
Published: October 2005

Decoding is the key step during protein synthesis that enables information transfer from RNA to protein, a process critical for the survival of all organisms. We have used large-scale (2.64 × 10
6
atoms) all-atom simulations of the entire ribosome to understand a critical step of decoding. Although the decoding problem has been studied for more than four decades, the rate-limiting step of cognate tRNA selection has only recently been identified. This step, known as accommodation, involves the movement inside the ribosome of the aminoacyl-tRNA from the partially bound “A/T” state to the fully bound “A/A” state. Here, we show that a corridor of 20 universally conserved ribosomal RNA bases interacts with the tRNA during the accommodation movement. Surprisingly, the tRNA is impeded by the A-loop (23S helix 92), instead of enjoying a smooth transition to the A/A state. In particular, universally conserved 23S ribosomal RNA bases U2492, C2556, and C2573 act as a 3D gate, causing the acceptor stem to pause before allowing entrance into the peptidyl transferase center. Our simulations demonstrate that the flexibility of the acceptor stem of the tRNA, in addition to flexibility of the anticodon arm, is essential for tRNA selection. This study serves as a template for simulating conformational changes in large (>10
6
atoms) biological and artificial molecular machines.
Interferon regulatory factor 4 negatively regulates the production of proinflammatory cytokines by macrophages in response to LPS
Authors: Honma Kiri , Udono Heiichiro , Kohno Tomoko , Yamamoto Kazuo , Ogawa Asako , Takemori Toshitada , Kumatori Atsushi , Suzuki Shoichi , Matsuyama Toshifumi , Yui Katsuyuki
Published: October 2005

A member of the IFN regulatory factor (IRF) family of transcription factors, IRF-4 is expressed in lymphocytes and macrophage/dendritic cells. Studies using IRF-4-deficient mice have revealed the critical roles of IRF-4 in lymphocyte responses. However, the role of IRF-4 in innate immune responses is not clearly understood. Here, we demonstrate that IRF-4 negatively regulates the production of proinflammatory cytokines by macrophages in response to Toll-like receptor (TLR) stimulation. Mice lacking IRF-4 are sensitive to LPS-induced shock, and their macrophages produce high levels of proinflammatory cytokines, including TNF-α and IL-6, in response to TLR ligands. The inhibitory role of IRF-4 in response to TLR stimulation was confirmed by the down-regulation of IRF-4 expression in normal macrophages by using the small interfering RNA technique and by the overexpression of IRF-4 in macrophage line RAW264.7. Activation of the important signaling pathways for cytokine production, NF-κB and JNK (c-Jun N-terminal kinase), was enhanced after LPS stimulation in IRF-4-/-macrophages. These results imply that IRF-4 negatively regulates TLR signaling and is inhibitory to the production of proinflammatory cytokines in response to TLR stimulation.
A genetic approach to access serotonin neurons forin vivoandin vitrostudies
Authors: Scott Michael M. , Wylie Christi J. , Lerch Jessica K. , Murphy RoxAnne , Lobur Katherine , Herlitze Stefan , Jiang Weihong , Conlon Ron A. , Strowbridge Ben W. , Deneris Evan S.
Published: October 2005

Serotonin (5HT) is a critical modulator of neural circuits that support diverse behaviors and physiological processes, and multiple lines of evidence implicate abnormal serotonergic signaling in psychiatric pathogenesis. The significance of 5HT underscores the importance of elucidating the molecular pathways involved in serotonergic system development, function, and plasticity. However, these mechanisms remain poorly defined, owing largely to the difficulty of accessing 5HT neurons for experimental manipulation. To address this methodological deficiency, we present a transgenic route to selectively alter 5HT neuron gene expression. This approach is based on the ability of a Pet-1 enhancer region to direct reliable 5HT neuron-specific transgene expression in the CNS. Its versatility is illustrated with several transgenic mouse lines, each of which provides a tool for 5HT neuron studies. Two lines allow Cre-mediated recombination at different stages of 5HT neuron development. A third line in which 5HT neurons are marked with yellow fluorescent protein will have numerous applications, including their electrophysiological characterization. To demonstrate this application, we have characterized active and passive membrane properties of midbrain reticular 5HT neurons, which heretofore have not been reported to our knowledge. A fourth line in which Pet-1 loss of function is rescued by expression of a Pet-1 transgene demonstrates biologically relevant levels of transgene expression and offers a route for investigating serotonergic protein structure and function in a behaving animal. These findings establish a straightforward and reliable approach for developing an array of tools forin vivoandin vitrostudies of 5HT neurons.
Mutagenesis-based definitions and probes of residue burial in proteins
Authors: Bajaj Kanika , Chakrabarti Purbani , Varadarajan Raghavan
Published: October 2005

Every residue of the 101-aaEscherichia colitoxin CcdB was substituted with Ala, Asp, Glu, Lys, and Arg by using site-directed mutagenesis. The activity of each mutantin vivowas characterized as a function of Controller of Cell Division or Death B protein (CcdB) transcriptional level. The mutation data suggest that an accessibility value of 5% is an appropriate cutoff for definition of buried residues. At all buried positions, introduction of Asp results in an inactive phenotype at all CcdB transcriptional levels. The average amount of destabilization upon substitution at buried positions decreases in the order Asp>Glu>Lys>Arg>Ala. Asp substitutions at buried sites in two other proteins, maltose-binding protein and thioredoxin, also were shown to be severely destabilizing. Ala and Asp scanning mutagenesis, in combination with dose-dependent expression phenotypes, was shown to yield important information on protein structure and activity. These results also suggest that such scanning mutagenesis data can be used to rank order sequence alignments and their corresponding homology models, as well as to distinguish between correct and incorrect structural alignments. With continuous reductions in oligonucleotide costs and increasingly efficient site-directed mutagenesis procedures, comprehensive scanning mutagenesis experiments for small proteins/domains are quite feasible.
Probing the active site tightness of DNA polymerase in subangstrom increments
Authors: Kim Tae Woo , Delaney James C. , Essigmann John M. , Kool Eric T.
Published: October 2005

We describe the use of a series of gradually expanded thymine nucleobase analogs in probing steric effects in DNA polymerase efficiency and fidelity. In these nonpolar compounds, the base size was increased incrementally over a 1.0-Å range by use of variably sized atoms (H, F, Cl, Br, and I) to replace the oxygen molecules of thymine. Kinetics studies with DNA Pol I (Klenow fragment, exonuclease-deficient)
in vitro
showed that replication efficiency opposite adenine increased through the series, reaching a peak at the chlorinated compound. Efficiency then dropped markedly as a steric tightness limit was apparently reached. Importantly, fidelity also followed this trend, with the fidelity maximum at dichlorotoluene, the largest compound that fits without apparent repulsion. The fidelity at this point approached that of wild-type thymine. Surprisingly, the maximum fidelity and efficiency was found at a base pair size significantly larger than the natural size. Parallel bypass and mutagenesis experiments were then carried out
in vivo
with a bacterial assay for replication. The cellular results were virtually the same as those seen in solution. The results provide direct evidence for the importance of a tight steric fit on DNA replication fidelity. In addition, the results suggest that even high-fidelity replicative enzymes have more steric room than necessary, possibly to allow for an evolutionarily advantageous mutation rate.
A fully dissociated compound of plant origin for inflammatory gene repression
Authors: De Bosscher Karolien , Berghe Wim Vanden , Beck Ilse M. E. , Van Molle Wim , Hennuyer Nathalie , Hapgood Janet , Libert Claude , Staels Bart , Louw Ann , Haegeman Guy
Published: October 2005

The identification of selective glucocorticoid receptor (GR) modifiers, which separate transactivation and transrepression properties, represents an important research goal for steroid pharmacology. Although the gene-activating properties of GR are mainly associated with undesirable side effects, its negative interference with the activity of transcription factors, such as NF-κB, greatly contributes to its antiinflammatory and immune-suppressive capacities. In the present study, we found that Compound A (CpdA), a plant-derived phenyl aziridine precursor, although not belonging to the steroidal class of GR-binding ligands, does mediate gene-inhibitory effects by activating GR. We demonstrate that CpdA exerts an antiinflammatory potential by down-modulating TNF-induced proinflammatory gene expression, such as IL-6 and E-selectin, but, interestingly, does not at all enhance glucocorticoid response element-driven genes or induce GR binding to glucocorticoid response element-dependent genesin vivo. We further show that the specific gene-repressive effect of CpdA depends on the presence of functional GR, displaying a differential phosphorylation status with CpdA as compared with dexamethasone treatment. The antiinflammatory mechanism involves both a reduction of thein vivoDNA-binding activity of p65 as well as an interference with the transactivation potential of NF-κB. Finally, we present evidence that CpdA is as effective as dexamethasone in counteracting acute inflammationin vivoand does not cause a hyperglycemic side effect. Taken together, this compound may be a lead compound of a class of antiinflammatory agents with fully dissociated properties and might thus hold great potential for therapeutic use.