bluuebunny/crossref_metadata_2025 huggingface dataset:
Emission lifetimes of europium-doped pyrochlores for phosphor thermometry
Authors: Hansel Rachael A. , Desai S. K. , Allison S. W. , Heyes A. L. , Walker D. G.
Published: January 2010

The luminescent lifetime of La2Zr2O7 and La2Hf2O7 has been determined as a function of temperature. We have shown that the luminescence of both materials can be used to determine the temperature of a surface up to 1073K. The results are qualitatively explained via multiphonon emission. Phonon energies and the number of phonons needed to cross the energy gap are estimated. The results are useful in the design of phosphors for noncontact thermometry in high-temperature applications.
Fully relaxed low-mismatched InAlAs layer on an InP substrate by using a two step buffer
Authors: Plissard S. , Coinon C. , Androussi Y. , Wallart X.
Published: January 2010

The strain relaxation in low mismatched InxAl1−xAs layers has been studied by triple axis x-ray diffraction, transmission electron microscopy, and photoluminescence. Using a two step buffer, a fully relaxed top layer has been grown by adapting the composition and thickness of a first “strained layer.” The threading dislocation density in the top layer is below 106/cm2 and strain is relaxed at the substrate/first layer interface by misfit dislocations. This scheme is a promising method to limit the thickness of buffer layers and obtain fully relaxed pseudosubstrates.
Size-dependent light output, spectral shift, and self-heating of 400 nm InGaN light-emitting diodes
Authors: Gong Zheng , Jin Shirong , Chen Yujie , McKendry Jonathan , Massoubre David , Watson Ian. M. , Gu Erdan , Dawson Martin D.
Published: January 2010

We have systematically investigated the impact of device size scaling on the light output, spectral shift, and self-heating of 400 nm InGaN light-emitting diodes (LEDs). Devices with diameters in the range 20–300 μm have been studied. It is shown that smaller LED pixels can deliver higher power densities (despite the lower absolute output powers) and sustain higher current densities. Investigations of the electroluminescence characteristics of differently sized pixels against current density reveal that the spectral shift is dominated by blueshift at the low current density level and then by redshift at the high current density level, owing to the competition between the bandgap shrinkage caused by self-heating and band-filling effects. The redshift of the emission wavelength with increasing current density is much faster and larger for the bigger pixels, suggesting that the self-heating effect is also size dependent. This is further confirmed by the junction-temperature rise measured by the established spectral shift method. It is shown that the junction-temperature rise in smaller pixels is slower, which in turn explains why the smaller redshift of the emission wavelength with current density is present in smaller pixels. The measured size-dependent junction temperature is in reasonable agreement with finite element method simulation results.
Modeling bound-to-continuum terahertz quantum cascade lasers: The role of Coulomb interactions
Authors: Jirauschek Christian , Matyas Alpar , Lugli Paolo
Published: January 2010

Based on an ensemble Monte Carlo analysis, we show that Coulomb interactions play a dominant role in bound-to-continuum terahertz quantum cascade lasers and thus require careful modeling. Coulomb interactions enter our simulation in the form of space charge effects as well as Coulomb scattering events. By comparison to a full many-subband Coulomb screening model, we show that simplified approaches produce considerable deviations for such structures. Also the spin dependence of electron-electron scattering has to be adequately considered. Moreover, we demonstrate that iterative Schrödinger–Poisson and carrier transport simulations are necessary to correctly account for space charge effects.
Refractive error correction for in situ curvature measurement using laser beam deflection method
Authors: Xiao Xinran , Schleh Daniel
Published: January 2010

Stoney’s equation allows one to calculate the internal stress in a thin film deposited on a thick substrate from the curvature of the bilayer beam. The curvature measurement is thus critical in the bending beam method, which is based on this equation. When an optical technique is used in curvature measurement, the refraction at optical boundaries needs to be corrected. An approximate correction to Stoney’s equation accounting for refractive error in the bending beam method in electrochemical applications was reported previously. This paper revisits the derivation. A set of diagrams for optical paths in in situ curvature measurement using the laser beam deflection method are presented. These diagrams allow us to establish the triangular relationships among the incident angles of the light beam and the deflection angle of the cantilever beam. Correction solutions are derived for three possible optical arrangements with the consideration of the travel distance of the light beam in liquid and in the container wall. In its approximated form, the correction derived in this paper differs from the previous formula by a factor of 2. It was discovered that an incorrect relationship for curvature was used in the previous derivation.
Phase relationships, and structural, magnetic, and magnetocaloric properties in the Ce5Si4–Ce5Ge4 system
Authors: Zhang H. , Mudryk Ya. , Cao Q. , Pecharsky V. K. , Gschneidner K. A. , Long Y.
Published: January 2010

The crystallography, phase relationships, and magnetic properties of the Ce5Si4−xGex alloys with 0≤x≤4 have been investigated by using x-ray powder diffraction and isothermal magnetization measurements. There are three different crystal structures in the Ce5Si4−xGex system: the Zr5Si4-type tetragonal structure with space group P41212 exists from 0≤x<2.15, the Gd5Si2Ge2-type monoclinic structure with space group P1121/a exists at x≈2.225, and the Sm5Ge4-type orthorhombic structure with space group Pnma is found for 2.4<x≤4. The magnetic ordering temperature increases when the tetragonal phase changes to the monoclinic phase, and then it remains composition independent throughout the orthorhombic phase, which is the opposite trend compared to that observed in the heavy lanthanide 5:4 compounds when Ge content increases. Another distinct difference is that Ce5Si4 exhibits an antiferromagnetic ground state while Ce5Ge4 phase orders ferromagnetically, which is reverse compared to the R5Si4−xGex systems where R=Gd and Tb. The magnetocaloric effect has been calculated from the magnetization data. The Ce5Ge4 has the maximum magnetic entropy change ΔSM(−11.6 J/kg K) at the Curie temperature of 11.5 K for a field change of 5 T.
Relationship between grain boundary structures in Si multicrystals and generation of dislocations during crystal growth
Authors: Usami Noritaka , Yokoyama Ryusuke , Takahashi Isao , Kutsukake Kentaro , Fujiwara Kozo , Nakajima Kazuo
Published: January 2010

We attempted to clarify relationship between grain boundary structures in Si multicrystals and generation of dislocations during crystal growth. Systematic variation of grain boundary structures was realized by employing dendritic nucleation at the initial stage of crystal growth. Etch-pit observation revealed that the contact angle of adjacent dendrite crystals to form a grain boundary affects generation of dislocations. Experimentally observed dislocation density was found to be well correlated with shear stress around the grain boundary calculated by finite element analysis.
Nanoindentation of virus capsids in a molecular model
Authors: Cieplak Marek , Robbins Mark O.
Published: January 2010

A molecular-level model is used to study the mechanical response of empty cowpea chlorotic mottle virus (CCMV) and cowpea mosaic virus (CPMV) capsids. The model is based on the native structure of the proteins that constitute the capsids and is described in terms of the Cα atoms. Nanoindentation by a large tip is modeled as compression between parallel plates. Plots of the compressive force versus plate separation for CCMV are qualitatively consistent with continuum models and experiments, showing an elastic region followed by an irreversible drop in force. The mechanical response of CPMV has not been studied, but the molecular model predicts an order of magnitude higher stiffness and a much shorter elastic region than for CCMV. These large changes result from small structural changes that increase the number of bonds by only 30% and would be difficult to capture in continuum models. Direct comparison of local deformations in continuum and molecular models of CCMV shows that the molecular model undergoes a gradual symmetry breaking rotation and accommodates more strain near the walls than the continuum model. The irreversible drop in force at small separations is associated with rupturing nearly all of the bonds between capsid proteins in the molecular model, while a buckling transition is observed in continuum models.
Production of negative osmium ions by laser desorption and ionization
Authors: Rodríguez D. , Sonnenschein V. , Blaum K. , Block M. , Kluge H.-J. , Lallena A. M. , Raeder S. , Wendt K.
Published: January 2010

The interest to produce negative osmium ions is manifold in the realm of high-accuracy ion trap experiments: high-resolution nearly Doppler-free laser spectroscopy, antihydrogen formation in its ground state, and contributions to neutrino mass spectrometry. Production of these ions is generally accomplished by sputtering an Os sample with Cs+ ions at tens of keV. Though this is a well-established method commonly used at accelerators, these kind of sources are quite demanding and tricky to operate. Therefore, the development of a more straightforward and cost effective production scheme will be of benefit for ion trap and other experiments. Such a scheme makes use of desorption and ionization with pulsed lasers and identification of the ions by time-of-flight mass spectrometry. First investigations of negative osmium ion production using a pulsed laser for desorption and ionization and a commercial matrix-assisted laser desorption/ionization time-of-flight system for identification has demonstrated the suitability of this technique. More than 103 negative osmium ions per shot were registered after bombarding pure osmium powder with a 5 ns pulse width Nd:yttrium aluminum garnet laser. The limitation in the ion number was imposed by the detection limit of the microchannel plate detector.
Enhancement of surface spin disorder in hollow NiFe2O4 nanoparticles
Authors: Jaffari G. Hassnain , Ceylan Abdullah , Ni C. , Shah S. Ismat
Published: January 2010

Hollow NiFe2O4 nanoparticles are synthesized by self-templating process utilizing coupled interfacial chemical reactions and Kirkendall effect between the core (Ni33Fe67) and the shell (NiFe2O4) of the core/shell structure. Reaction temperature and time dependent structural and morphogical transformations are presented in detail. The kinetics of the transformation from (Ni33Fe67)/(NiFe2O4) nanoparticles to single phased NiFe2O4 hollow nanoparticles was studied by differential scanning calorimetry. Hollow morphology of the particles induces surface effects in the magnetic properties due to the formation of additional inner surfaces. Field cooled hysteresis loop exhibits significantly large shift due to unidirectional anisotropy resulting from the additional inner spin disordered surface along with the existing outer spin disordered surface. The enhancement in the surface anisotropy is also noticeable which leads to an increase in the blocking temperature of the particles with hollow morphology.
Ferromagnetic clusters in the Brownmillerite bilayered compounds Ca2.5−xLaxSr0.5GaMn2O8: An approach to achieve layered spintronics materials
Authors: Bera A. K. , Yusuf S. M.
Published: January 2010

We report the effect of La substitution on the magnetic and magnetotransport properties of Brownmillerite-like bilayered compounds Ca2.5−xLaxSr0.5GaMn2O8 (x=0, 0.05, 0.075, and 0.1) by using dc magnetization, resistivity, and magnetoresistance techniques. The Rietveld analysis of the room temperature x-ray diffraction patterns confirms no observable change in average crystal structure with the La substitution. Both magnetic and magnetotransport properties are found to be very sensitive to the La substitution. Interestingly, the La-substituted compounds show ferromagneticlike behavior (due to the occurrence of a double exchange mechanism), whereas the parent compound is an antiferromagnet (TN∼150 K). All compounds show an insulating behavior in the measured temperature range of 100–300 K, with an overall decrease in the resistivity with the substitution. A higher value of magnetoresistance has been successfully achieved by the La substitution. We have proposed an electronic phase separation model, considering the formation of ferromagnetic clusters in the antiferromagnetic matrix, to interpret the observed magnetization and magnetotransport results for the La-substituted samples. The present study demonstrates an approach to achieve new functional materials, based on naturally occurring layered system like Ca2.5−xLaxSr0.5GaMn2O8, for possible spintronics applications.
Transition times in the low-noise limit of stochastic dynamics
Authors: Malinin Sergey V. , Chernyak Vladimir Y.
Published: January 2010

We study the transition time distribution for a particle moving between two wells of a multidimensional potential in the low-noise limit of overdamped Langevin dynamics. Possible transition paths are restricted to a thin tube surrounding the most probable trajectory. We demonstrate that finding the transition time distribution reduces to a one-dimensional problem. The resulting transition time distribution has a universal and compact form. We suggest that transition barriers can be estimated from a single-temperature experiment if both the life times and the transition times are measured.
Optical resonances created by photonic transitions
Authors: Yu Zongfu , Fan Shanhui
Published: January 2010

We show that a high-Q optical resonance can be created dynamically, by inducing a photonic transition between a localized state and a one-dimensional continuum through refractive index modulation. In this mechanism, both the frequency and the external linewidth of a single resonance are specified by the dynamics, allowing complete control of the resonance properties. An example using photonic crystal heterostructure cavity is demonstrated with numerical simulation. We also show that the reported effect can be accomplished with realistic index modulation strength and frequencies.
Detection of electric field around field-reversed configuration plasma
Authors: Ikeyama Taeko , Hiroi Masanori , Ohkuma Yasunori , Nogi Yasuyuki
Published: January 2010

Electric-field probes consisting of copper plates are developed to measure electric fields in a vacuum region around a plasma. The probes detect oscillating electric fields with a maximum strength of approximately 100 V/m through a discharge. Reproducible signals from the probes are obtained with an unstable phase dominated by a rotational instability. It is found that the azimuthal structure of the electric field can be explained by the sum of an n=2 mode charge distribution and a convex-surface electron distribution on the deformed separatrix at the unstable phase. The former distribution agrees with that anticipated from the diamagnetic drift motions of plasma when the rotational instability occurs. The latter distribution suggests that an electron-rich plasma covers the separatrix.
Theoretical and experimental studies of stressed nanoparticles of II-VI semiconductors
Authors: Ferreira D. Lourençoni , Silva F. Oliveira , Viol L. Cristina de Souza , Licínio P. , Schiavon M. Antônio , Alves J. Luiz Aarestrup
Published: January 2010

A theoretical and experimental study of isolated nanoparticles of II-VI semiconductor materials has been done. Using the framework of the effective mass model, the optical absorption spectrum of distributions of spherical quantum dots, freestanding, and under compressive or tensile stress, has been examined theoretically. The theoretical results allow one to foresee the absorption spectra of quantum dots made of a series of materials and having any size. The syntheses of colloidal quantum dots of CdS and CdSe has also been performed through wet chemical routes and characterized by means of optical techniques. The values of the strains in the synthesized quantum dots were inferred from a correlation established between the theoretical and the experimental results.
Modulational instability of dust acoustic solitons in multicomponent plasma with kappa-distributed electrons and ions
Authors: Gill T. S. , Bains A. S. , Bedi C.
Published: January 2010

In the present investigation the modulational instability (MI) of dust acoustic wave (DAW) in four-component dusty plasma consisting of negative and positive charged dust grains and kappa (κ) distributed electrons and ions is studied. Considering the multifluid plasma model and using the reductive perturbation technique, nonlinear Schrödinger equation, which governs the MI of DAW, is obtained. It is found that presence of positive dust component, kappa-distributed electrons (κe), ions (κi), and temperature ratio (σ) significantly modify the domain of the MI and localized envelope excitations. Further, the effects of these parameters on the growth rate of MI have also been discussed in detail.
Improved efficiency of hybrid solar cells based on non-ligand-exchanged CdSe quantum dots and poly(3-hexylthiophene)
Authors: Zhou Yunfei , Riehle Frank S. , Yuan Ying , Schleiermacher Hans-Frieder , Niggemann Michael , Urban Gerald A. , Krüger Michael
Published: January 2010

We report on bulk-heterojunction hybrid solar cells based on blends of non-ligand-exchanged CdSe quantum dots (QDs) and the conjugated polymer poly(3-hexylthiophene) with improved power conversion efficiencies of about 2% under AM1.5G illumination after spectral mismatch correction. This is the highest reported value for a spherical CdSe QD based photovoltaic device. After synthesis, the CdSe QDs are treated by a simple and fast acid-assisted washing procedure, which has been identified as a crucial factor in enhancing the device performance. A simple model of a reduced ligand sphere is proposed explaining the power conversion efficiency improvement.
Langmuir monolayers with internal dipoles: Understanding phase behavior using Monte Carlo simulations
Authors: George Christopher B. , Ratner Mark A. , Szleifer Igal
Published: January 2010

A coarse-grained, rigid-rod model that includes steric interactions and an internal dipole is used to study monolayers of surfactant molecules tethered to a flat interface. Monte Carlo simulations are performed in the canonical ensemble for a range of high-density configurations with varying degrees of dipole strength. Both a melting transition and a tilting transition are observed, and the dependence of the transitions on the surfactant molecules’ internal dipoles is examined. Simulation results indicate that at high packing densities, the monolayers exist in a frustrated state due to dipole-dipole repulsions and steric interactions. Tilting of the surfactant molecules increases the magnitude of the dipole-dipole attractions and lowers the overall system energy, but is limited by steric repulsions. In simulations with higher dipole strengths, the melting and tilting transitions are found to be coupled. The formation of nanodomains with increased collective tilt and positional order in these systems suggests a possible mechanism for the coupling.
Self-organized growth of high density magnetic Co nanodot arrays on a Moiré template
Authors: Fernández L. , Corso M. , Schiller F. , Ilyn M. , Holder M. , Ortega J. E.
Published: January 2010

We report the self-organized growth of cobalt nanodot arrays using a Gd-Au Moiré superlattice as a template. After analyzing the influence of the Co flux and the substrate temperature, we obtain the suitable parameters to maximize nanodot density, homogeneity, and individual size. Depending on the growth conditions an areal density of up to 54 Teradots/inch2 can be achieved. Below the limit of lateral coalescence, independent nanodots made of ∼1000 Co atoms exhibit room temperature remanent magnetization.
Large enhancement in photon detection sensitivity via Schottky-gated CdS nanowire nanosensors
Authors: Wei Te-Yu , Huang Chi-Te , Hansen Benjamin J. , Lin Yi-Feng , Chen Lih-Juann , Lu Shih-Yuan , Wang Zhong Lin
Published: January 2010

The Schottky contact based photon detection was demonstrated using CdS (visible light responsive), silicon (indirect n-type oxygen-non-adsorbing), and CuO (indirect p-type oxygen-adsorbing) nanowire nanosensors. With changing one of the two nanowire-electrode contacts from ohmic to Schottky, detection sensitivities as high as 105% were achieved by the CdS nanowire nanosensor operated at the reverse bias mode of −8 V, which was 58 times higher than that of the corresponding ohmic contact device. The reset time was also significantly reduced. In addition, originally light nonresponsive silicon and CuO nanowires became light responsive when fabricated as a Schottky contact device. These improvements in photon detection can be attributed to the Schottky gating effect realized in the present nanosensor system by introducing a Schottky contact.
Observation and characterization of laser-driven phase space electron holes
Authors: Sarri G. , Dieckmann M. E. , Brown C. R. D. , Cecchetti C. A. , Hoarty D. J. , James S. F. , Jung R. , Kourakis I. , Schamel H. , Willi O. , Borghesi M.
Published: January 2010

The direct observation and full characterization of a phase space electron hole (EH) generated during laser-matter interaction is presented. This structure, propagating in a tenuous, nonmagnetized plasma, has been detected via proton radiography during the irradiation with a ns laser pulse (Iλ2≈1014 W/cm2) of a gold hohlraum. This technique has allowed the simultaneous detection of propagation velocity, potential, and electron density spatial profile across the EH with fine spatial and temporal resolution allowing a detailed comparison with theoretical and numerical models.
Strain-induced lateral self-organization in Si/SiO2 nanostructures
Authors: Tsybeskov L. , Kamenev B. V. , Sirenko A. A. , McCaffrey J. P. , Lockwood D. J.
Published: January 2010

We show that strain, arising from the mismatch between Si and SiO2 thermal expansion coefficients, directs the thermal crystallization of amorphous Si along Si/SiO2 interfaces, and produces continuous, fully crystallized nanometer thick Si layers with a lateral-to-vertical aspect ratio close to 100:1. These Si nanolayers exhibit a low density of structural defects and are found to be elastically strained with respect to the crystal Si substrate.
Spinning droplets on superhydrophobic surfaces
Authors: Burkarter E. , Berlim L. S. , Schreiner W. H. , Saul C. K.
Published: January 2010

The study of liquid droplets on solid surfaces is a well established research area. Static measurements include contact angle determinations which allow surface energy measurement. Dynamic measurements generally are reported on vibrating drops on mechanically or sonic driven surfaces. The general analysis of the physics of vibrating drops is complicated due to the internal degrees of freedom of the liquid and the stick or slip conditions at the liquid-solid contact line. Here we propose a simple and straightforward experimental method to measure the physical properties of droplets on highly hydrophobic surfaces. The first dynamic experiments of droplets on superhydrophobic surfaces are also reported.
Optical and Electronic Properties of Doubly Ortho-linked cis-4,4'-Bis(diarylamino)stilbene/Fluorene Hybrids
Authors: Liu Yan-Ling , Ran Xue-Qin , Feng Ji-Kang , Ren Ai-Min , Zou Lu-Yi
Published: January 2010

Doubly ortho-linked cis-4,4′-bis(diarylamino)stilbene/fluorene hybrids have potential application in organic light emitting diodes. These organic molecules can function as efficient hole transport materials, with sky-blue emission and high efficiency and stability. To reveal the relationship between the properties and structures of these functional materials, we apply quantum-chemical techniques to investigate their optical properties and electronic structures. It is found that 8- and 8′-substituents give an antibonding contribution to the highest occupied molecular orbitals (HOMO), thus increasing the HOMO energy, implying an enhancement of hole-creating ability. Changes in ionization potentials confirm this presumption. The absorption and emission spectra exhibit red shifts to some extent with the various 8- and 8′-substituents, which are in good agreement with the experimental values. The Stoke shifts range moderately from 40 to 86 nm, due to the rigid spiral structure that hinders geometrical relaxation.
Transition Metal-Substituted Double Dawson-Type Polyoxotungstates and Their Supramolecular Structures
Authors: Yao Shuang , Zhang Zhiming , Li Yangguang , Wang Enbo
Published: January 2010

Reactions of hexavacant polyoxotungstate [H2P2W12O48]12– ({P2W12}) with various transition metal cations lead to the isolation of three double Dawson-type polyoxotungstates: (C4H10NO)12Na2[α
1-MnP2W17O61]2·7H2O (1), [(CH3)2NH2]3K2Na11[α
1-CoP2W17O61]2·30H2O (2), and Na8K2[Fe2(H2O)8(Fe2P2W16O60)2]·41H2O (3). Compound 1 has a one-dimensional (1D) supramolecular architecture built from a Mn-substituted double Dawson-type polyoxoanion (DDTP) [α
1-MnP2W17O61]2
14–, morpholine, and lattice water molecules. Compound 2 has a 1D supramolecular structure built from the first Co-containing DDTP [α
1-CoP2W17O61]2
16– connected via H-bonding interactions. Compound 3 has a 3D supramolecular structure built from a Fe-substituted DDTP [Fe2(H2O)8(Fe2P2W16O60)2]10– and lattice water molecules. Electrocatalytic studies indicate that these three compounds all display electrocatalytic activity toward the reduction of nitrite.
Chemical Modifications on 4-Arylpiperazine-Ethyl Carboxamide Derivatives Differentially Modulate Affinity for 5-HT1A, D4.2, and α2A Receptors: Synthesis and In Vitro Radioligand Binding Studies
Authors: Graulich Amaury , Léonard Marc , Résimont Mélissa , Huang Xi-Ping , Roth Bryan L. , Liégeois Jean-François
Published: January 2010

A series of substituted 4-aryl-piperazine-ethyl heteroarylcarboxamides were prepared and tested in in vitro radioligand binding studies. The presence of a quinoxaline has a favourable impact in terms of serotonin 5-HT1A versus dopamine D4.2 receptor selectivity. Compounds with a 3-CF3 group at the distal phenyl ring are the most effective in terms of affinity and selectivity for 5-HT1A versus D4.2 receptors. A 4-phenyl-1,2,3,6-tetrahydropyridine in place of the corresponding 4-phenyl-piperazine side chain is also favourable not only for the affinity for 5-HT1A and D4.2 receptors but also in some cases for α 2A-adrenoceptors.
Detection of Impurities in Organic Peroxide Explosives from Precursor Chemicals
Authors: Partridge Andrew , Walker Stewart , Armitt David
Published: January 2010

Previous analyses of organic peroxide explosives have focussed on identification of the explosive itself, and were performed using explosive samples synthesized from laboratory-grade precursors. In this work, analytical studies of precursors obtained from retail outlets identified compounds that could be carried over into the explosives as impurities during synthesis. Forensic and intelligence information may be gained by the identification of possible precursor impurities in explosive samples. This hypothesis was tested using triacetone triperoxide and hexamethylene triperoxide diamine prepared from domestically available off-the-shelf precursors. Gas chromatography–mass spectrometry analysis showed that compounds originating from such precursors could be detected in the organic peroxide samples at different stages in their purification. Furthermore, some compounds could also be detected in the residues of samples that had been subjected to thermal initiation.
Research Front Essay: Forensic Chemistry
Authors: Robertson James
Published: January 2010

The author discusses the benefits for forensic science from greater engagement with basic and other applied areas of chemistry and gives examples of how his organization, the Australian Federal Police, have partnered with academia and others to promote the use of chemistry in areas of trace evidence, illicit drugs, fingerprint detection, and explosives.
Solution structure of the cap-independent translational enhancer and ribosome-binding element in the 3
′
UTR of turnip crinkle virus
Authors: Zuo Xiaobing , Wang Jinbu , Yu Ping , Eyler Dan , Xu Huan , Starich Mary R. , Tiede David M. , Simon Anne E. , Kasprzak Wojciech , Schwieters Charles D. , Shapiro Bruce A. , Wang Yun-Xing
Published: January 2010

The 3
′
untranslated region (3
′
UTR) of turnip crinkle virus (TCV) genomic RNA contains a cap-independent translation element (CITE), which includes a ribosome-binding structural element (RBSE) that participates in recruitment of the large ribosomal subunit. In addition, a large symmetric loop in the RBSE plays a key role in coordinating the incompatible processes of viral translation and replication, which require enzyme progression in opposite directions on the viral template. To understand the structural basis for the large ribosomal subunit recruitment and the intricate interplay among different parts of the molecule, we determined the global structure of the 102-nt RBSE RNA using solution NMR and small-angle x-ray scattering. This RNA has many structural features that resemble those of a tRNA in solution. The hairpins H1 and H2, linked by a 7-nucleotide linker, form the upper part of RBSE and hairpin H3 is relatively independent from the rest of the structure and is accessible to interactions. This global structure provides insights into the three-dimensional layout for ribosome binding, which may serve as a structural basis for its involvement in recruitment of the large ribosomal subunit and the switch between viral translation and replication. The experimentally determined three-dimensional structure of a functional element in the 3
′
UTR of an RNA from any organism has not been previously reported. The RBSE structure represents a prototype structure of a new class of RNA structural elements involved in viral translation/replication processes.
What Is Wrong with Typological Thinking?
Authors: Lewens Tim
Published: January 2010

What, if anything, is wrong with typological thinking? The question is important, for some evolutionary developmental biologists appear to espouse a form of typology. I isolate four allegations that have been brought against it. They include the claim that typological thinking is mystical; the claim that typological thinking is at odds with the fact of evolution; the claim that typological thinking is committed to an objectionable metaphysical view, which Elliott Sober calls the ‘natural state model’; and finally the view (endorsed by Ron Amundson and Günter Wagner) that typological thinking—and specifically evolutionary developmental biology's typological thinking—is committed to a peculiar form of causation that does not fit neatly into the causal models endorsed by population genetics. I argue that, properly understood, the typological thinking of evolutionary developmental biology does not run into any of these problems.
Discussion: The Physical Unnaturalness of Churchland's Ellipses
Authors: Wright Wayne
Published: January 2010

This article addresses Paul Churchland's attempt to identify colors with surface reflectance spectra. Of particular concern is Churchland's novel method of approximating surface reflectance spectra. While those approximations are generated by objective means and yield a striking match with human phenomenological color space, they are not physically meaningful. The reason for this is that the method used to produce the approximations induces equivalence classes on surface reflectances that are not invariant under physically appropriate changes of measurement convention. This result undermines Churchland's proposed response to the objection from metamers commonly raised against color physicalism, as his surface reflectance approximations are supposed to provide an objective, physical unifying basis for metamers.
Influenza Vaccination among Healthcare Workers: Ten-Year Experience of a Large Healthcare Organization
Authors: Ajenjo M. Cristina , Woeltje Keith F. , Babcock Hilary M. , Gemeinhart Nancy , Jones Marilyn , Fraser Victoria J.
Published: January 2010

Objective.

To describe the results of different measures implemented to improve adherence to the healthcare worker (HCW) influenza immunization program at BJC HealthCare during the period from 1997 through 2007.

Design.

Descriptive retrospective study.

Setting.

BJC HealthCare, a 13-hospital nonprofit healthcare organization in the Midwest.

Methods.

We reviewed and analyzed HCW influenza vaccination data from all BJC HealthCare Occupational Health Services and hospitals during the period from 1997 through 2007. Occupational health staff, infection prevention personnel, and key influenza vaccination campaign leaders were also interviewed regarding implementation measures during the study years.

Results.

At the end of 2007, BJC HealthCare had approximately 26,000 employees. With the use of multiple progressive interventions, influenza vaccination rates among BJC employees increased from 45% in 1997 to 72% in 2007 (P<.001). The influenza vaccination rate in 2007 was significantly higher than in 2006: 72%, compared with 54% (P<.001). Five hospitals had influenza vaccination rates that exceeded the target goal of 80% in 2007. The most successful interventions were adding influenza vaccination rates to the quality scorecard incentive program and the use of declination statements, both of which were implemented in 2007. The most important barriers to success identified by interview respondents were HCWs' misconceptions about influenza vaccination and a perceived lack of leadership support.

Conclusions.

Influenza vaccination rates among HCWs significantly improved with multiple interventions over the years. However, the BJC HealthCare influenza vaccination target of 80% was not attained at all hospitals with these measures. More aggressive interventions, such as implementing mandatory influenza vaccination policies, are needed to achieve higher vaccination rates.
Inhibition of Human Cervical Cancer Cell Growth by Ethanolic Extract of Boerhaavia diffusa Linn. (Punarnava) Root
Authors: Srivastava Rakhi , Saluja Daman , Dwarakanath Bilikere S. , Chopra Madhu
Published: January 2010

In Indian traditional medicine, Boerhaavia diffusa (punarnava) roots have been widely used for the treatment of dyspepsia, jaundice, enlargement of spleen, abdominal pain and as an anti‐stress agent. Pharmacological evaluation of the crude ethanolic extract of B. diffusa roots has been shown to possess antiproliferative and immunomodulatory properties. The extract of B. diffusa was studied for anti‐proliferative effects on the growth of HeLa cells and for its effect on cell cycle. Bio‐assays of extracts from B. diffusa root showed that a methanol : chloroform fraction (BDF 5) had an antiproliferative effect on HeLa cells. After 48 h of exposure, this fraction at a concentration of 200 μg mL−1 significantly reduced cell proliferation with visible morphological changes in HeLa cells. Cell cycle analysis suggests that antiproliferative effect of BDF 5 could be due to inhibition of DNA synthesis in S‐phase of cell cycle in HeLa cells, whereas no significant change in cell cycle was detected in control cells. The fraction BDF 5 caused cell death via apoptosis as evident from DNA fragmentation and caspase‐9 activation. Thus the extract has potential to be evaluated in detail to assess the molecular mechanism‐mediated anticancer activities of this plant.
Trend analysis of indicators: a comparison of recent changes in the status of marine ecosystems around the world
Authors: Blanchard Julia L. , Coll Marta , Trenkel Verena M. , Vergnon Rémi , Yemane Dawit , Jouffre Didier , Link Jason S. , Shin Yunne-Jai
Published: January 2010

Blanchard, J. L., Coll, M., Trenkel, V. M., Vergnon, R., Yemane, D., Jouffre, D., Link, J. S., and Shin, Y-J. 2010. Trend analysis of indicators: a comparison of recent changes in the status of marine ecosystems around the world. – ICES Journal of Marine Science, 67: 732–744. Time-series of ecological and exploitation indicators collected from 19 ecosystems were analysed to investigate whether there have been temporal trends in the status of fish communities. Using linear and non-linear statistical methods, trends are reported for six indicators (mean length of fish in the community, mean lifespan, proportion of predatory fish, total biomass of surveyed species, mean trophic level of landings, and inverse fishing pressure), and the redundancy of these indicators across ecosystems is evaluated. The expected direction of change for an ecosystem that is increasingly impacted by fishing is a decline in all indicators. A mixture of negative and positive directions of change is recorded, both within and among all ecosystems considered. No consistent patterns in the redundancy of the ecological indicators across ecosystems emerged from the analyses, confirming that each indicator provided complementary information on ecosystem status. The different trends in indicators may reflect differing historical exploitation patterns, management, and environmental regimes in these systems. Commitment to monitoring programmes and development of system-specific baseline, target, and threshold reference levels are required. Improved understanding of the responsiveness and performance of ecological indicators to management actions are needed to address adequately whether ecosystems are recovering from, or being further impacted by, fishing, and whether management targets are being met. The relative effects of multiple environmental and ecological processes as well as multiple human-induced stressors that characterize exploited ecosystems also need to be quantified.
Pathogenicity and Management of Olpidium bornovanus, a Root Pathogen of Melons
Authors: Stanghellini M. E. , Mathews D. M. , Misaghi I. J.
Published: January 2010

Greenhouse studies document, for the first time, that Olpidium bornovanus, an obligate, holocarpic, root-inhabiting zoosporic fungus heretofore regarded as a nonpathogenic parasite, is a root pathogen. Significant browning of the roots and reductions in shoot and root growth were recorded within 28 days following inoculation of melons with the fungus. Amending the recirculating nutrient solution with either a nonionic surfactant (Agral 90) or a strobilurin fungicide (azoxystrobin) resulted in efficacious management of the disease caused by the fungus.
Multiple Resistance to Meloidogyne spp. and to Bipartite and Monopartite Begomovirus spp. in Wild Solanum (Lycopersicon) Accessions
Authors: Pereira-Carvalho R. C. , Boiteux L. S. , Fonseca M. E. N. , Díaz-Pendón J. A. , Moriones E. , Fernández-Muñoz R. , Charchar J. M. , Resende R. O.
Published: January 2010

The Ty-1 locus confers tolerance to monopartite and bipartite Begomovirus spp. (genus Begomovirus, family Geminiviridae) and this phenotype is improved in homozygous tomato lines. However, the gene Mi (Meloidogyne spp. resistance) is in repulsion phase linkage with Ty-1, which hampers the large-scale development of multiresistant inbred lines. Seventy-one Solanum (section Lycopersicon) accessions were whitefly inoculated with the bipartite Begomovirus sp. Tomato rugose mosaic virus (ToRMV) and simultaneously infested with a mixture of Meloidogyne incognita and M. javanica under greenhouse conditions in Brazil. Accessions were then transplanted into a nematode-infested field with natural ToRMV infection. A severity index was used to evaluate ToRMV reaction. Nematode evaluation was done by counting the number of galls per root system. Seventeen accessions with Meloidogyne spp. and ToRMV resistance were selected and evaluated in Spain against three monopartite Begomovirus spp. associated with the tomato yellow leaf curl virus disease, using infectious clones. Systemic infection was monitored by DNA hybridization. Five S. peruvianum accessions (PI-306811, PI-365951, LA-1609, LA-2553, and CNPH-1194) displayed nematode and broad-spectrum resistance to all Begomovirus spp. tested in both continents. From the breeding standpoint, accessions combining resistance to Meloidogyne spp. and to bipartite and monopartite Begomovirus spp. would be useful for the development of elite lines expressing all traits in homozygous condition.
Geographic Distribution of Fungicide-Insensitive Sclerotinia homoeocarpa Isolates from Golf Courses in the Northeastern United States
Authors: Putman Alexander I. , Jung Geunhwa , Kaminski John E.
Published: January 2010

Chemical management of dollar spot in turf may lead to the development of Sclerotinia homoeocarpa populations with reduced fungicide sensitivity. The objective of this study was to determine the scope of S. homoeocarpa insensitivity to fungicides commonly used to control dollar spot on golf courses in the northeastern United States. A total of 965 and 387 isolates of S. homoeocarpa from intensively or individually sampled sites, respectively, were evaluated for in vitro sensitivity to iprodione, propiconazole, and thiophanate-methyl. Mean baseline sensitivities to iprodione and propiconazole were 0.2763 and 0.0016 μg a.i. ml–1, respectively, and all baseline isolates were sensitive to thiophanate-methyl at 1,000 μg a.i. ml–1. When compared with the baseline population, 14 and 18 of 20 total populations were less sensitive to iprodione and propiconazole, respectively. Individually sampled isolates obtained from fairways, putting greens, or tees were less sensitive to iprodione and propiconazole when compared with the baseline. For thiophanate-methyl, five populations were sensitive, six were resistant, and the remaining nine populations contained various proportions (2 to 92%) of resistant isolates. Individually sampled isolates obtained from fairways and putting greens were evaluated for associations in sensitivity among the three fungicides. A weak but positive correlation in sensitivity to iprodione and propiconazole was observed for isolates resistant to thiophanate-methyl but correlations for sensitive isolates were not significant. Furthermore, isolates with highly reduced sensitivity to iprodione clustered in a narrow range of propiconazole sensitivity. These data suggest the possible existence of resistance mechanisms common to diverse fungicide classes. Overall, results indicate that insensitivity of S. homoeocarpa to iprodione, propiconazole, and thiophanate-methyl exists in varying degrees on golf courses in the northeastern United States.
Spatial and Temporal Incidences of Pineapple mealybug wilt-associated viruses in Pineapple Planting Blocks
Authors: Sether D. M. , Borth W. B. , Melzer M. J. , Hu J.
Published: January 2010

A complex of Pineapple mealybug wilt-associated viruses (PMWaVs) that can infect pineapple (Ananas comosus) is correlated with reduced yields and mealybug wilt of pineapple. The incidences of PMWaV-1 and PMWaV-2 at planting, fruit harvest, the beginning of the ratoon crop, and ratoon fruit harvest were determined for end, side, and central regions of planting blocks in eight commercial fields. Differences in virus incidence for the three regions at ratoon harvest were highly significant (P = 0.0018). Central regions of planting blocks had lower virus incidences at the time of ratoon fruit harvest. Collection of propagation material from the central regions of planting blocks will help to minimize PMWaV incidence in fields planted with this material.
Managing Foliar Diseases of Processing Sweet Corn in New York with Strobilurin Fungicides
Authors: Shah D. A. , Dillard H. R.
Published: January 2010

Processing sweet corn (Zea mays) growers in New York are more concerned about the cost effectiveness of fungicide use against foliar fungal diseases (common rust and Northern corn leaf blight) and less about whether such sprays will reduce disease intensity. To address this concern, field trials were done in 2006 and 2007 with three processing sweet corn hybrids (Jubilee, Bold, and GH 9597) that differed in susceptibility to common rust and Northern corn leaf blight, and two strobilurin fungicides (azoxystrobin and pyraclostrobin). Single strobilurin applications were applied in response to foliar disease severity thresholds of 1, 10, and 20%. Single fungicide applications did reduce foliar disease severities. Applications were most cost effective when made in response to the 1 and 10% foliar severity thresholds, and generally only in the susceptible hybrid Bold. Spraying at the 20% severity threshold did reduce final foliar disease severity but was not cost effective. Azoxystrobin and pyraclostrobin were equally effective in disease management. The results suggest that a single application of a strobilurin fungicide against common rust and Northern corn leaf blight can be cost effective for New York processing sweet corn growers when such an application is made before foliar disease severity exceeds 20%.
Development of Race-Specific SCAR Markers for Detection of Chinese Races CYR32 and CYR33 of Puccinia striiformis f. sp. tritici
Authors: Wang Baotong , Hu Xiaoping , Li Qiang , Hao Baojun , Zhang Bo , Li Gaobao , Kang Zhensheng
Published: January 2010

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, is a devastating disease in China. Races CYR32 and CYR33 have been predominant in the recent P. striiformis f. sp. tritici population. To develop molecular markers for these races, initially 86 isolates, most of which were collected in 2007 throughout China, were tested on the set of wheat genotypes for differentiating Chinese P. striiformis f. sp. tritici races, and their genomic DNA were amplified with 94 random amplified polymorphic DNA (RAPD) primers. Twelve isolates were identified as CYR33, 14 as CYR32, and 60 as 13 other races. A 320-bp band was identified to be associated with CYR32 with primer S1271 (5′-CTTCTCGGTC-3′), and a 550-bp band was identified to be specific to CYR33 with primer S1304 (5′-AGGAGCGACA-3′). The two bands were cloned and sequenced. Based on the sequences, sequence characterized amplified region (SCAR) markers CYR32sp1/sp2 and CYR33sp1/sp2 were developed to differentiate CYR32 and CYR33, respectively, from other races. The SCAR markers were validated with DNA samples from wheat leaves inoculated with selected isolates from the 86 isolates and urediniospore DNA samples from an additional 63 isolates collected from 2006 to 2009. The detection of CYR32 and CYR33 with the SCAR markers was completely consistent with the results of the race identification with the set of differential wheat genotypes. Thus, the markers are highly reliable for identification of the two races.