bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible micromorph tandem a-Si/μc-Si solar cells
Authors: Söderström T. , Haug F.-J. , Terrazzoni-Daudrix V. , Ballif C.
Published: January 2010

The deposition of a stack of amorphous (a-Si:H) and microcrystalline (μc-Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of μc-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the μc-Si:H cell and the light-induced degradation of the a-Si:H cell. As a result, μc-Si:H cell has to grow on a smooth substrate with large periodicity (>1 μm) and the a-Si:H cell on sharp pyramids with smaller feature size (∼350 nm) to strongly scatter the light in the weak absorption spectra of a-Si:H material. The asymmetric intermediate reflector introduced in this work uncouples the growth and light scattering issues of the tandem micromorph solar cells. The stabilized efficiency of the tandem n-i-p/n-i-p micromorph is increased by a relative 15% compared to a cell without AIR and 32% in relative compared to an a-Si:H single junction solar cells. The overall process (T<200 °C) is kept compatible with low cost plastic substrates. The best stabilized efficiency of a cell deposited on polyethylene-naphthalate plastic substrate is 9.8% after 1000 h of light soaking at Voc, 1 sun, and 50 °C.
Large-scale parallel configuration interaction. II. Two- and four-component double-group general active space implementation with application to BiH
Authors: Knecht Stefan , Jensen Hans Jørgen Aa. , Fleig Timo
Published: January 2010

We present a parallel implementation of a large-scale relativistic double-group configuration interaction (CI) program. It is applicable with a large variety of two- and four-component Hamiltonians. The parallel algorithm is based on a distributed data model in combination with a static load balancing scheme. The excellent scalability of our parallelization scheme is demonstrated in large-scale four-component multireference CI (MRCI) benchmark tests on two of the most common computer architectures, and we also discuss hardware-dependent aspects with respect to possible speedup limitations. With the new code we have been able to calculate accurate spectroscopic properties for the ground state and the first excited state of the BiH molecule using extensive basis sets. We focused, in particular, on an accurate description of the splitting of these two states which is caused by spin-orbit coupling. Our largest parallel MRCI calculation thereby comprised an expansion length of 2.7×109 Slater determinants.
A second generation distributed point polarizable water model
Authors: Kumar Revati , Wang Fang-Fang , Jenness Glen R. , Jordan Kenneth D.
Published: January 2010

A distributed point polarizable model (DPP2) for water, with explicit terms for charge penetration, induction, and charge transfer, is introduced. The DPP2 model accurately describes the interaction energies in small and large water clusters and also gives an average internal energy per molecule and radial distribution functions of liquid water in good agreement with experiment. A key to the success of the model is its accurate description of the individual terms in the n-body expansion of the interaction energies.
Calculating electron cyclotron current drive stabilization of resistive tearing modes in a nonlinear magnetohydrodynamic model
Authors: Jenkins Thomas G. , Kruger Scott E. , Hegna C. C. , Schnack Dalton D. , Sovinec Carl R.
Published: January 2010

A model which incorporates the effects of electron cyclotron current drive (ECCD) into the magnetohydrodynamic equations is implemented in the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)] and used to investigate the effect of ECCD injection on the stability, growth, and dynamical behavior of magnetic islands associated with resistive tearing modes. In addition to qualitatively and quantitatively agreeing with numerical results obtained from the inclusion of localized ECCD deposition in static equilibrium solvers [A. Pletzer and F. W. Perkins, Phys. Plasmas 6, 1589 (1999)], predictions from the model further elaborate the role which rational surface motion plays in these results. The complete suppression of the (2,1) resistive tearing mode by ECCD is demonstrated and the relevant stabilization mechanism is determined. Consequences of the shifting of the mode rational surface in response to the injected current are explored, and the characteristic short-time responses of resistive tearing modes to spatial ECCD alignments which are stabilizing are also noted. We discuss the relevance of this work to the development of more comprehensive predictive models for ECCD-based mitigation and control of neoclassical tearing modes.
Time-resolved measurements of double layer evolution in expanding plasma
Authors: Scime E. E. , Biloiu I. A. , Carr J. , Thakur S. Chakraborty , Galante M. , Hansen A. , Houshmandyar S. , Keesee A. M. , McCarren D. , Sears S. , Biloiu C. , Sun X.
Published: January 2010

Observations in steady-state plasmas confirm predictions that formation of a current-free double layer in a plasma expanding into a chamber of larger diameter is accompanied by an increase in ionization upstream of the double layer. The upstream plasma density increases sharply at the same driving frequency at which a double layer appears. For driving frequencies at which no double layer appears, large electrostatic instabilities are observed. Time-resolved measurements in pulsed discharges indicate that the double layer initially forms for all driving frequencies. However, for particularly strong double layers, instabilities appear early in the discharge and the double layer collapses.
Large amplitude dynamics of micro-/nanomechanical resonators actuated with electrostatic pulses
Authors: Juillard J. , Bonnoit A. , Avignon E. , Hentz S. , Colinet E.
Published: January 2010

In the field of resonant nano-electro-mechanical system (NEMS) design, it is a common misconception that large-amplitude motion, and thus large signal-to-noise ratio, can only be achieved at the risk of oscillator instability. In the present paper, we show that very simple closed-loop control schemes can be used to achieve stable large-amplitude motion of a resonant structure even when jump resonance (caused by electrostatic softening or Duffing hardening) is present in its frequency response. We focus on the case of a resonant accelerometer sensing cell, consisting of a nonlinear clamped-clamped beam with electrostatic actuation and detection, maintained in an oscillation state with pulses of electrostatic force that are delivered whenever the detected signal (the position of the beam) crosses zero. We show that the proposed feedback scheme ensures the stability of the motion of the beam much beyond the critical Duffing amplitude and that, if the parameters of the beam are correctly chosen, one can achieve almost full-gap travel range without incurring electrostatic pull-in. These results are illustrated and validated with transient simulations of the nonlinear closed-loop system.
Electronic energy levels and carrier dynamics in InAs/InGaAs dots-in-a-well structure investigated by optical spectroscopy
Authors: Chen Rui , Liu H. Y. , Sun H. D.
Published: January 2010

We investigate the electronic energy levels and carrier dynamics in InAs/InxGa1−xAs dots-in-a-well (DWELL) structure by comprehensive spectroscopic characterization over a temperature range from 10 to 300 K. The integrated photoluminescence (PL) intensity is observed to increase with raising temperature up to 100 K. Through combining the PL and PL excitation (PLE) analysis, we provide direct evidence that this anomalous temperature dependence of the PL spectrum is due to the carrier trapping in InGaAs quantum well at low temperature. A rate equation model is adopted to quantitatively describe the thermal escape and capture processes of carriers in the DWELL system. The origin of thermal activation energies for quantum dot PL quenching at higher temperatures is discussed referring to the electronic energy levels revealed by PLE spectra.
Ultrafast gated imaging of laser produced plasmas using the optical Kerr effect
Authors: Symes D. R. , Wegner U. , Ahlswede H.-C. , Streeter M. J. V. , Gallegos P. L. , Divall E. J. , Smith R. A. , Rajeev P. P. , Neely D.
Published: January 2010

Optical imaging is a versatile diagnostic for investigations of plasmas generated under intense laser irradiation. Electro-optic gating techniques operating on the >100 ps timescale are commonly used to reduce the amount of light detected from self-emission of hot plasma or improve the temporal resolution of the detector. The use of an optical Kerr gate enables a superior dynamic range and temporal resolution compared to electronically gated devices. The application of this method for enhanced imaging of laser produced plasmas with gate time ∼100 fs is demonstrated, and the possibility to produce a sub-10 fs, high dynamic range “all optical” streak camera is discussed.
Frequency-dependent behaviors of individual microscopic particles in an optically induced dielectrophoresis device
Authors: Zhu Xiaolu , Yi Hong , Ni Zhonghua
Published: January 2010

An optoelectronic microdevice is set up to drive single microparticles and a maximum synchronous velocity (MS-velocity) spectrum method is proposed for quantifying the frequency-dependent behaviors of individual neutral microparticles from 40 kHz to 10 MHz. Dielectrophoretic behaviors of three types of microparticles are investigated under the optically induced nonuniform electric field. Different MS-velocity spectra for the three different particles are experimentally found. Numerical calculations for the MS-velocity spectra of polystyrene microparticles are performed. The spectrum of the MS-velocities for a specific particle is mainly determined by the particle inherent property and the electric characteristics of the device. Moreover the experimental and the numerical MS-velocity spectra are compared to be accordant. Based on the dielectrophoretic (DEP) behaviors of the particles under a nonuniform electric field, microparticles can be finely characterized or distinguished according to their distinct MS-velocity spectra.
Flexible high-frequency microwave inductors and capacitors integrated on a polyethylene terephthalate substrate
Authors: Sun Lei , Qin Guoxuan , Huang Hai , Zhou Han , Behdad Nader , Zhou Weidong , Ma Zhenqiang
Published: January 2010

This letter reports the realization of bendable inductors and capacitors integrated on a polyethylene terephthalate substrate that can operate at high microwave frequencies. A low-temperature fabrication process compatible with flexible thin-film transistors (TFTs) was developed. By employing bendable dielectric materials, spiral inductors and metal-insulator-metal capacitors with high quality factors and high resonance frequencies were demonstrated. The effects of mechanical bending on the performance of inductors and capacitors were also measured and analyzed. These demonstrations combined with previously demonstrated microwave TFTs will lead to flexible radio-frequency and microwave systems in the future.
Dynamic programming based time-delay estimation technique for analysis of time-varying time-delay
Authors: Gupta Deepak K. , McKee George R. , Fonck Raymond J.
Published: January 2010

A new time-delay estimation (TDE) technique based on dynamic programming is developed to measure the time-varying time-delay between two signals. The dynamic programming based TDE technique provides a frequency response five to ten times better than previously known TDE techniques, namely, those based on time-lag cross-correlation or wavelet analysis. Effects of frequency spectrum, signal-to-noise ratio, and amplitude of time-delay on response of the TDE technique (represented as transfer function) are studied using simulated data signals. The transfer function for the technique decreases with increase in noise in signal; however it is independent of signal spectrum shape. The dynamic programming based TDE technique is applied to the beam emission spectroscopy diagnostic data to measure poloidal velocity fluctuations, which led to the observation of theoretically predicted zonal flows in high-temperature tokamak plasmas.
Monodispersed cation-disordered cubic AgInS2 nanocrystals with enhanced fluorescence
Authors: Feng Zhenyu , Dai Pengcheng , Ma Xicheng , Zhan Jinhua , Lin Zhaojun
Published: January 2010

Monodispersed metastable cubic AgInS2 nanocrystals with an average size of around 2.5 nm are obtained via a solution-phase reaction. In contrast with the usual chalcopyrite and orthorhombic phase, Ag+ and In3+ cations in metastable cubic AgInS2 are randomly coordinated by four S2− anions. A phase transition from cation-disordered cubic to orthorhombic AgInS2 occurs with the increased reaction temperature or elongated reaction time. The photoluminescence quantum yield of cation-disordered cubic AgInS2 nanocrystals could reach 10% at room temperature, which is much higher than that of orthorhombic AgInS2 nanocrystals obtained via a similar approach.
Quasichemical and structural analysis of polarizable anion hydration
Authors: Rogers David M. , Beck Thomas L.
Published: January 2010

Quasichemical theory is utilized to analyze the relative roles of solute polarization and size in determining the structure and thermodynamics of bulk anion hydration for the Hofmeister series Cl−, Br−, and I−. Excellent agreement with experiment is obtained for whole salt hydration free energies using the polarizable AMOEBA force field. The total hydration free energies display a stronger dependence on ion size than on polarizability. The quasichemical approach exactly partitions the solvation free energy into inner-shell, outer-shell packing, and outer-shell long-ranged contributions by means of a hard-sphere condition. The inner-shell contribution becomes slightly more favorable with increasing ion polarizability, indicating electrostriction of the nearby waters. Small conditioning radii, even well inside the first maximum of the ion-water(oxygen) radial distribution function, result in Gaussian behavior for the long-ranged contribution that dominates the ion hydration free energy. This in turn allows for a mean-field treatment of the long-ranged contribution, leading to a natural division into first-order electrostatic, induction, and van der Waals terms. The induction piece exhibits the strongest ion polarizability dependence, while the larger-magnitude first-order electrostatic piece yields an opposing but weaker polarizability dependence. The van der Waals piece is small and positive, and it displays a small ion specificity. The sum of the inner-shell, packing, and long-ranged van der Waals contributions exhibits little variation along the anion series for the chosen conditioning radii, targeting electrostatic effects (influenced by ion size) as the largest determinant of specificity. In addition, a structural analysis is performed to examine the solvation anisotropy around the anions. As opposed to the hydration free energies, the solvation anisotropy depends more on ion polarizability than on ion size: increased polarizability leads to increased anisotropy. The water dipole moments near the ion are similar in magnitude to bulk water, while the ion dipole moments are found to be significantly larger than those observed in quantum mechanical studies. Possible impacts of the observed over-polarization of the ions on simulated anion surface segregation are discussed.
Interacting electrons, spin statistics, and information theory
Authors: Ghiringhelli L. M. , Hamilton I. P. , Delle Site L.
Published: January 2010

We consider a nearly (or quasi) uniform gas of interacting electrons for which spin statistics play a crucial role. A previously developed procedure, based on the extension of the Levy–Lieb constrained search principle and Monte Carlo sampling of electron configurations in space, allows us to approximate the form of the kinetic-energy functional. For a spinless electron gas, this procedure led to a correlation term, which had the form of the Shannon entropy, but the resulting kinetic-energy functional does not satisfy the Lieb–Thirring inequality, which is rigorous and one of the most general relations regarding the kinetic energy. In this paper, we show that when the fermionic character of the electrons is included via a statistical spin approach, our procedure leads to correlation terms, which also have the form of the Shannon entropy and the resulting kinetic-energy functional does satisfy the Lieb–Thirring inequality. In this way we further strengthen the connection between Shannon entropy and electron correlation and, more generally, between information theory and quantum mechanics.
Bias and temperature dependent charge transport in high mobility cobalt-phthalocyanine thin films
Authors: Samanta S. , Aswal D. K. , Singh A. , Debnath A. K. , Kumar M. Senthil , Hayakawa Y. , Gupta S. K. , Yakhmi J. V.
Published: January 2010

The temperature dependent current-voltage (J-V) characteristics of highly-oriented cobalt phthalocyanine films (rocking-curve width=0.11°) deposited on (001) LaAlO3 substrates are investigated. In the temperature range 300–100 K, charge transport is governed by bulk-limited processes with a bias dependent crossover from Ohmic (J∼V) to trap-free space-charge-limited conduction (J∼V2). The mobility (μ) at 300 K has a value of ∼7 cm2 V−1 s−1 and obeys Arrhenius-type (ln μ∼1/T) behavior. However, at temperatures <100 K, the charge transport is electrode-limited, which undergoes a bias dependent transition from Schottky (ln J∼V1/2) to multistep-tunneling (conductivity varying exponentially on the inverse of the square-root of electric field).
High efficiency green, yellow, and amber emission from InGaN/GaN dot-in-a-wire heterostructures on Si(111)
Authors: Chang Y.-L. , Wang J. L. , Li F. , Mi Z.
Published: January 2010

The authors report on the achievement of nearly defect-free, vertically aligned InGaN/GaN dot-in-a-wire nanoscale heterostructures grown directly on Si(111) substrates by molecular beam epitaxy. Strong green, yellow, and amber emission, with a room temperature internal quantum efficiency of ∼45% of that measured at low temperature (∼10 K), was achieved. Detailed structural and optical studies further confirm that the emission characteristics are strongly influenced by the presence of In-rich nanoclusters, formed by phase segregation, in the InGaN dots.
Quantum trajectory dynamics in imaginary time with the momentum-dependent quantum potential
Authors: Garashchuk Sophya
Published: January 2010

The quantum trajectory dynamics is extended to the wave function evolution in imaginary time. For a nodeless wave function a simple exponential form leads to the classical-like equations of motion of trajectories, representing the wave function, in the presence of the momentum-dependent quantum potential in addition to the external potential. For a Gaussian wave function this quantum potential is a time-dependent constant, generating zero quantum force yet contributing to the total energy. For anharmonic potentials the momentum-dependent quantum potential is cheaply estimated from the global Least-squares Fit to the trajectory momenta in the Taylor basis. Wave functions with nodes are described in the mixed coordinate space/trajectory representation at little additional computational cost. The nodeless wave function, represented by the trajectory ensemble, decays to the ground state. The mixed representation wave functions, with lower energy contributions projected out at each time step, decay to the excited energy states. The approach, illustrated by computing energy levels for anharmonic oscillators and energy level splitting for the double-well potential, can be used for the Boltzmann operator evolution.
Piezoelectric accelerometers for ultrahigh temperature application
Authors: Zhang Shujun , Jiang Xiaoning , Lapsley Michael , Moses Paul , Shrout Thomas R.
Published: January 2010

High temperature sensors are of major importance to aerospace and energy related industries. In this letter, a high temperature monolithic compression-mode piezoelectric accelerometer was fabricated using YCa4O(BO3)3 (YCOB) single crystals. The performance of the sensor was tested as function of temperature up to 1000 °C and over a frequency range of 100–600 Hz. The accelerometer prototype was found to possess sensitivity of 2.4±0.4 pC/g, across the measured temperature and frequency range, indicating a low temperature coefficient. Furthermore, the sensor exhibited good stability over an extended dwell time at 900 °C, demonstrating that YCOB piezoelectric accelerometers are promising candidates for high temperature sensing applications.
Vortical structures in a nonuniform pair-ion dust magnetoplasma with sheared flows
Authors: Mushtaq A. , Qamar A. , Ahmed Zulfiqar
Published: January 2010

It has been shown that sheared pair-ion flows can generate low frequency electrostatic waves in a nonuniform dust pair-ion magnetoplasma. Linear analysis shows that the electrostatic driftlike waves can become unstable due to shear flow. The conditions of modes instability are given. These excited modes gain large amplitudes and start interacting among themselves. The interaction is governed by the nonlinear equations containing the vector nonlinearities. Stationary solutions of the nonlinear mode coupling equations can be represented in the form of a vortex chain and a dipolar vortex. The relevance of the work to laboratory plasmas are pointed out.
A quantitative assessment of the accuracy of centroid molecular dynamics for the calculation of the infrared spectrum of liquid water
Authors: Paesani Francesco , Voth Gregory A.
Published: January 2010

A detailed analysis of the infrared lineshapes corresponding to the intramolecular bond vibrations of HOD in either H2O or D2O is presented here in order to quantitatively assess the accuracy of centroid molecular dynamics in reproducing the correct features of the infrared spectrum of water at ambient conditions. Through a direct comparison with the results obtained from mixed quantum-classical calculations, it is shown that centroid molecular dynamics provides accurate vibrational shifts and lineshapes when the intramolecular bond stretching vibrations are described by a physically reasonable anharmonic potential. Artificially large redshifts due to a so-called “curvature problem” are instead obtained with an unphysical shifted harmonic potential because the latter allows substantial probability density at zero bond lengths.
An Improved and Rapid Radiochemical Method for the Determination of Polonium-210 in Urine
Authors: Manickam Elizabeth , Sdraulig Sandra , O'Brien Richard
Published: January 2010

Measurements of radionuclides in urine are widely used to assess the health impact of intakes of radionuclides. The events that followed the polonium poisoning in London in late 2006 have highlighted the need for rapid and reliable methods that can be applied to emergency situations. Ideally such a method would also be applicable to the routine assessment of radionuclides in urine. This paper discusses the development and validation of such a method for measuring the concentration of 210Po in urine. The method is validated by assessment of the selectivity, accuracy and recovery, and quantification of the uncertainty. The paper describes two variations of the method, based on whether the priority is a rapid turnaround, or higher sensitivity. The detection limit for the excretion rate of 210Po can range from 1.5 to 20 mBq d–1 depending on the dose limit requirements for different categories of exposure (public, occupational, or emergency).
The Synthesis and Preliminary Pharmacological Evaluation of a Series of Substituted 4'-Phenoxypropyl Analogues of the Atypical Antipsychotic Clozapine
Authors: Capuano Ben , Crosby Ian T. , McRobb Fiona M. , Podloucka Anna , Taylor David A. , Vom Amelia , Yuriev Elizabeth
Published: January 2010

Herein we report the synthesis, characterization, and preliminary pharmacological activity of a new series of substituted 4′-phenoxypropyl tricyclic analogues of clozapine as potential antipsychotic agents for the treatment of schizophrenia. The lead compound (3) for this investigation was designed based on a revised model derived from the structural hybridization of the commercial therapeutics clozapine (1) and haloperidol (2). The compounds described in this paper probe the biochemical effects of introducing a variety of electron-withdrawing and electron-donating substituents with the primary focus on the para-position of the introduced distal aromatic ring. The target compounds were readily prepared in three steps using the key intermediate lactam (8-chloro-10,11-dihydro-5H-dibenzo[b,e][1,4]diazepine-11-one, 9), piperazine and commercially available substituted phenols. The chemistry and structural characterization of this series of substituted 4′-phenoxypropyl analogues of clozapine are described. Preliminary in vitro results on the pharmacological effects of the ring substituents on affinity for dopamine D4 and serotonin 5-HT2A receptors are discussed. Psychosis-related in vivo animal behavioural data for compounds identified with potential from the receptor binding screen are also presented.
Recent Advances in the Application of Stable Isotope Ratio Analysis in Forensic Chemistry
Authors: Daeid Niamh Nic , Buchanan Hilary A. S. , Savage Kathleen A. , Fraser James G. , Cresswell Sarah L.
Published: January 2010

This review paper updates the previous literature in relation to the continued and developing use of stable isotope ratio analysis in samples which are relevant to forensic science. Recent advances in the analysis of drug samples, explosive materials, and samples derived from human and animal samples are discussed. The paper also aims to put the use of isotope ratio mass spectrometry into a forensic context and discuss its evidential potential.
Counterion Effects and Dynamics of Parathion in Anionic Lyomesophases
Authors: Bahamonde Victor , Ahumada Hernán , Araya-Maturana Ramiro , Weiss-López Boris E.
Published: January 2010

Ingestion of parathion produces catastrophic effects on mammals. Transformed into paraoxon, it inhibits acetylcholinesterase, producing acetylcholine accumulation. The distribution, orientation, and dynamics of parathion in different hydrophobic bilayer environments is interesting from both ecological and biological perspectives. A study of parathion-d4 dissolved in two nematic discotic lyotropic liquid crystals made of sodium and cesium decylsulfate (CsDS and NaDS)/decanol (10% 1,1-dideuterodecanol)/water (0.1% D2O)/M2SO4 (M = Na+, Cs+), is presented. Deuterium quadrupole splittings and relaxation times of all deuteriated species were measured. Parathion is strongly attached to both aggregates, increasing the alignment of CsDS and decreasing the alignment of NaDS. Molecular dynamics trajectories were calculated for both mesophases. CsDS appears more neutralized than NaDS. Despite the surface charge, parathion is associated to both aggregates, located near the interface, with the nitro group oriented to the headgroups and the ethoxy chains toward the hydrophobic core. When included in the CsDS interface, it stabilizes the system by shielding repulsive electrostatic interactions among headgroups. Included in NaDS, parathion induces an increase in the distance among counterions and sulfate headgroups, thus decreasing the degree of order.
There and Back Again, or the Problem of Locality in Biodiversity Surveys
Authors: Shavit Ayelet , Griesemer James
Published: January 2010

We argue that ‘locality’, perhaps the most mundane term in ecology, holds a basic ambiguity: two concepts of space—nomothetic and idiographic—which are both necessary for a rigorous resurvey to “the same” locality in the field, are committed to different practices with no common measurement. A case study unfolds the failure of the standard assumption that an exogenous grid of longitude and latitude, as fine-grained as one wishes, suffices for revisiting a species locality. We briefly suggest a scale-dependent “resolution” for this replication problem, since it has no general, rational solution.
Are Homologies (Selected Effect or Causal Role) Function Free?
Authors: Rosenberg Alex , Neander Karen
Published: January 2010

This article argues that at least very many judgments of homology rest on prior attributions of selected-effect (SE) function, and that many of the “parts” of biological systems that are rightly classified as homologous are constituted by (are so classified in virtue of) their consequence etiologies. We claim that SE functions are often used in the prior identification of the parts deemed to be homologous and are often used to differentiate more restricted homologous kinds within less restricted ones. In doing so, we discuss recent criticism of this view that has been offered (especially that offered by Paul Griffiths).
Establishment of the Yellow Starthistle Rust in California: Release, Recovery, and Spread
Authors: Woods Dale M. , Fisher Alison J. , Villegas Baldo
Published: January 2010

The rust fungus Puccinia jaceae var. solstitialis is the first pathogen released for biological control of yellow starthistle (Centaurea solstitialis). From 2004 to 2006, the pathogen was released at 176 sites in 40 counties throughout the state of California. Release sites were evaluated 1 to 3 months and 1, 2, and, in some cases, 3 years after releases to monitor for reemergence. At 1 to 3 months after inoculation, 58 to 93% of sites had rust infection, depending on the year. After 1, 2, and 3 years, the percentages declined to 19 to 21, 9 to 10, and 3% respectively. Spread was detected at 19% of the sites with rust infection, with an average distance of 21 m (±13.3 standard error). The greatest spread occurred at a site in Sonoma County. At this site, the rust spread to over 37 acres 1 year after it was released and has remained in this area for three seasons. Reemergence 1 and 2 years after inoculations was more likely in Northern (above 40°N) compared with Southern California (below 36°N). In general, reemergence was more likely at lower elevations when release sites were within 150 km of the coast. Overall, the rust has not demonstrated a strong record of persistence based on these observations.
Control of Postharvest Gray Mold of Table Grapes in the San Joaquin Valley of California by Fungicides Applied During the Growing Season
Authors: Smilanick J. L. , Mansour M. F. , Mlikota Gabler F. , Margosan D. A. , Hashim-Buckey J.
Published: January 2010

Fungicides applied before harvest were evaluated to control postharvest gray mold of table grapes, caused by Botrytis cinerea. The concentrations of thiophanate methyl (THM), iprodione (IPR), cyprodinil (CYP), pyraclostrobin + boscalid (PS+BO), pyrimethanil (PYR), or fenhexamid (FEN) that inhibited the growth of four isolates sensitive to these fungicides by 50% (EC50) were 12.4, 2.5, 0.61, 0.29/0.57, 0.26, or 0.17 mg liter-1, respectively. THM, IPR, CYP, PS+BO, PYR, or FEN were applied to detached ‘Thompson Seedless’ berries at the equivalent of the maximum approved rates of 600, 500, 270, 59/116, 370, or 290 mg liter-1, respectively, except PS+BO, which were used at 54.2% of their current registered maximum rates. The berries were inoculated with B. cinerea 48 or 24 h before treatment or 24 or 48 h after treatment. Gray mold 2 weeks after treatment and storage at 15°C was lowest after FEN application, followed by PYR, CYP, IPR, PS+BO, and THM. In commercial vineyards, one application of FEN, PYR, CYP, or PS+BO, all at their current maximum approved rates, 2 weeks before harvest reduced postharvest gray mold by approximately 50%. When fungicides were applied repeatedly after berry set either in mixtures or alternated with fungicides of different mode of action classes, postharvest gray mold was reduced by about 50% using a commercial air-blast sprayer and by 70 to 87% using a hand-held sprayer that was directed into the clusters. The fungicide sensitivity of isolates collected in numerous vineyards indicated those with reduced sensitivity to all of the tested fungicides, except FEN, were common. The efficacy of preharvest fungicide regimes was not sufficient to replace postharvest sulfur dioxide fumigation.
Effects of Surface Wetness Periods on Development of Soybean Rust Under Field Conditions
Authors: Narváez Dario F. , Jurick Wayne M. , Marois James J. , Wright David L.
Published: January 2010

Soybean rust (SBR), caused by Phakopsora pachyrhizi, has the potential to be an economic threat to U.S. soybean production after its arrival to the continental United States in 2004. The use of fungicides to control SBR may be problematic due to the large acreage that needs to be protected, the high costs of fungicides, and the cost of application. Cultural practices such as the use of reduced seed rates, increased row widths, and row orientation to the sun have been prescribed as environmental modifications that create a microclimate less conducive to foliar disease development. Therefore, our objective was to determine the influence of different periods of leaf wetness and respective microenvironments on infection and rust development on soybean plants in the field. A misting irrigation system was developed and applied on MGV soybean for 1 min every 30 min for 0-, 6-, 12-, and 18-h periods. This study indicates that extended periods of leaf wetness (18 h) increase disease severity and the rate of spread of the disease in the upper canopy. These results, in combination with spore monitoring, may be used to refine models of pathogen reproduction, prediction, and risk in a certain regions.
First Report of Meloidogyne enterolobii on Arrowroot in China
Authors: Zhuo K. , Hu M. X. , Liao J. L. , Rui K.
Published: January 2010

The rhizome of arrowroot (Maranta arundinacea L.) is used as a source of edible starch in many tropical/subtropical areas. In July 2009, cultivated arrowroot plants in a field in Haikou, Hainan Province, China were observed to be exhibiting symptoms of decline, including stunting and yellowing. Roots of affected plants were found to have severe root galling similar to that caused by root-knot nematodes. Meloidogyne sp. females were dissected from the galls. Morphological characteristics of the females fit the description of M. enterolobii Yang & Eisenback (4). The perineal patterns were variable, with moderately high to high dorsal arch and mostly lacking lateral lines, but when present, the lines were not conspicuous, similar to those in the original description.(4). For further confirmation of species identity, isoenzyme patterns of malate dehydrogenase (Mdh) and esterase (Est) phenotypes were analyzed and partial sequences of mtDNA were obtained. Enzyme electrophoresis showed that the phenotypes of Mdh and Est were N1a and VS1-S1 respectively, which were consistent with those of M. enterolobii (1). Amplification and sequencing of the mtDNA between COII and the lRNA gene was accomplished with primers C2F3 (5′-GGTCAATGTTCAGAAATTTGTGG-3′) and 1108 (5′-TACCTTTGACCAATCACGCT-3′) (2). A DNA fragment of 705 bp was obtained and the sequence (GenBank Accession No. GQ870255) was compared with those in GenBank. A BLAST search indicated the sequence was 100% identical to the sequences of M. mayaguensis (GenBank Accession Nos. AY446969 and AY446970), a synonym of M. enterolobii (3). On the basis of these results, the root-knot nematodes isolated from arrowroot in Hainan were confirmed as M. enterolobii. This species has a high reproduction rate and a wide host range; moreover, it can induce severe galling and is able to overcome the resistance gene Mi-1 in tomato and pepper (4). M. enterolobii has become increasingly important because it has been found in many countries on diverse hosts. In China in recent years, the nematode has been reported on approximately 20 plant species belonging to five families, including Fabaceae, Cucurbitaceae, Solanaceae, Myrtaceae, and Annonaceae. To our knowledge, this is the first record of M. enterolobii parasitizing a plant (i.e., arrowroot) in the family Marantaceae in China.

References: (1) P. R. Esbenshade and A. C. Triantaphyllou. J. Nematol. 17:6, 1985. (2) T. O. Powers and T. S. Harris. J. Nematol. 25:1, 1993. (3) J. Xu et al. Eur. J. Plant Pathol. 110:309, 2004. (4) B. Yang and J. D. Eisenback. J. Nematol. 15:381, 1983.
First Report of Buxus rotundifolia Root and Collar Rot Caused by Phytophthora citrophthora in Italy
Authors: Vettraino A. M. , Franceschini S. , Vannini A.
Published: January 2010

Boxwood (Buxus spp.) includes several species of popular ornamental shrubs used in traditional and contemporary gardening. In March of 2008, a gradual and irreversible decline was observed on 6-year-old Buxus rotundifolia plants in a garden in central Italy. Of 150 boxwood plants, 70% were symptomatic, and among them, approximately 25% were completely wilted. Aboveground symptoms included stunting, necrotic bark lesions at the base of the stem, reduced growth, and leaf chlorosis. Leaves at first appeared light green, then turned yellow, bronze, or straw colored. Foliar symptoms were restricted to a few branches or extended to the whole crown. Immunological field tests (Pocket Diagnostic, CSL Diagnostics, Milan, Italy) on necrotic rootlets and bark tissues suggested the risk of the presence of Phytophthora spp. One species was consistently isolated on PARHP (2) from necrotic tissues of three symptomatic plants. Recovered isolates were heterothallic and produced aerial mycelium. Star-like compact growth was also observed on potato dextrose agar. Cultures on carrot agar submerged in saline solution (2) developed papillate, noncaducous, and sympodially branched sporangia of different shapes ranging from ovoid to obturbinate. Sporangia were 37.5 to 65.0 × 22.5 to 35.0 μm (average 49.0 × 31.0 μm); L/W ratio from 1.1 to 2.1 (average 1.6). On the basis of morphological features, these isolates belong to P. citrophthora (R.E. Sm. & E.H. Sm.) Leonian (2). The identity was confirmed by sequencing of the internal transcribed spacer region of the rDNA (NCBI Accession No. FJ874794). Inoculum for two isolates of P. citrophthora (3BO and 4BO) was produced for pathogenicity testing on 100 g of autoclaved millet grains moistened with 70 ml of V8 juice. Two, 2-liter aliquots of potting media were each amended with the infested grains (1:20 vol/vol) and five 3-year-old plants of B. rotundifolia per isolate were transplanted into the media. Plants were maintained in a growth chamber at 18 to 22°C, with relative humidity of 80%, and a 12-h photoperiod. Sterile millet grains were used to inoculate five boxwood plants for the control. After 2 months, control plants remained healthy while inoculated plants displayed root necroses and foliar symptoms similar to those observed in the field. The pathogen, consistently reisolated from roots of infected plants, reduced the root weight by an average of 25%. Root rot of boxwood plants is reported to be caused by P. citricola in Poland (4), P. parasitica in Virginia (3), and P. citrophthora in North Carolina (1). To our knowledge, this is the first report of P. citrophthora on B. rotundifolia in Europe.

References: (1) Z. G. Abad et al. Plant Dis. 78:830, 1994. (2) D. C. Erwin and O. K. Ribeiro. Page 562 in: Phytophthora Diseases Worldwide. The American Phytopathological Society. St. Paul, MN, 1996. (3) M. A. Hansen. Plant Dis. Fact Sheets. 450-614W, 2000. (4) L. B. Orlikowski. J. Plant Prot. Res. 46:163, 2006.
First Report of Crown and Root Rot Caused by Binucleate Rhizoctonia AG-A on Thryptomene saxicola in Italy
Authors: Polizzi G. , Aiello D. , Castello I. , Vitale A. , Kato M. , Hyakumachi M.
Published: January 2010

Thryptomene saxicola (Hook.) Schauer is an evergreen shrub native to Western Australia and a member of the Myrtaceae. In Italy, this species was recently introduced as an ornamental plant from abroad. From July of 2008 to September 2009, a new crown and root rot of T. saxicola was observed on several stocks of approximately 20,000 1- to 3-year-old potted plants. Diseased plants were obtained from a commercial nursery in eastern Sicily, Italy. They were propagated from cuttings and grown under drip irrigation. More than 30% of the plants showed disease symptoms. Infected plants were characterized by a lack of vigor. Roots and crowns were partially or completely destroyed, and as a consequence, infected plants were chlorotic and often wilted. Early in the disease development, roots and crowns showed brown lesions. Successively, mature crown lesions turned dark brown. Longitudinal sections of crown tissues revealed a discoloration of the basal stem. Diseased tissues were surface disinfested for 1 min in 1% NaOCl, rinsed in sterile water, plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate, and then incubated at 25°C. A binucleate Rhizoctonia (BNR) species was consistently isolated from affected tissues of plants. Phytophthora isolates were not recovered from symptomatic tissues plated on BNPRAH (benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol) selective medium. Fungal colonies were white with floccose, aerial hyphae. Hyphal cells were determined to be binucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates with five different tester isolates of BNR AG-A on 2% water agar in petri plates (3). Anastomosis was observed with all tester isolates. The rDNA-ITS of one isolate of BNR (DISTEF-TS1) was sequenced (GenBank Accession No. AB514570) (2). The sequence from this isolate exhibited 99% homology with BNR AG-A (GenBank Accession No. AY738628). Pathogenicity tests were conducted on potted, healthy, 1-year-old plants of T. saxicola. Forty plants were inoculated by placing 1/cm2 plugs of PDA from 5-day-old mycelial cultures near the base of the stem. The same number of plants was treated with 1/cm2 PDA plugs as controls. Plants were kept at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Root and crown rots, identical to those observed in the nursery, appeared 45 days after inoculation, and 80% of the inoculated plants died within 4 months. Control plants remained healthy. Binucleate Rhizoctonia was reisolated from symptomatic tissues, completing Koch's postulates. To our knowledge, this is the first report in the world of BNR causing disease on T. saxicola.

References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) M. Hyakumachi et al. Phytopathology 95:784, 2005. (3) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.
Root and Crown Rot of Anthurium Caused by Calonectria ilicicola in Iran
Authors: Mirabolfathy M. , Groenewald J. Z. , Crous P. W.
Published: January 2010

In the autumn of 2008, a severe disease of Anthurium andraeanum with wilting and root and crown rot symptoms was observed in a greenhouse in the Varamin area of Tehran. A species of Calonectria was isolated consistently from symptomatic tissues on 2% potato dextrose agar (PDA). The fungus produced perithecia and a Cylindrocladium anamorph when incubated on carnation leaf agar under near-ultraviolet light at 25°C. Perithechia were reddish brown, subglobose to ovoid, and 300 to 400 μm in diameter. Asci were clavate, hyaline, 90 to 140 × 12 to 19 μm, and tapering to a long thin stalk. Ascospores were fusoid, straight to slightly curved, 1- (-3) septate, and (30-) 37 to 50 (-65) × (4-) 5 to 6.5 (-7) μm (mean = 45 × 6 μm; n = 30). Penicillate conidiophores gave rise to stipe extensions that terminated in sphaeropedunculate vesicles (6-) 7 to 10 (-12) μm in diameter. Conidia were hyaline, cylindrical, rounded at both ends, straight, (45-) 70 to 82 (-90) × (4-) 5 to 6.5(-7) μm (mean = 62 × 6 μm; n = 30), and (1-) 3-septate. On the basis of morphology, the fungus was identified as Calonectria ilicicola Boedijin & Reitsma. Koch's postulates were fulfilled by spray inoculating 1-month-old seedlings with a conidial and mycelial suspension (105 particles per ml) of the fungus obtained from 14-day-old single-spore colonies grown on PDA at 25°C. Following inoculation, all plants were maintained in plastic bags in a glasshouse at 25 ± 1°C. After 15 to 25 days, symptoms resembling those seen in the diseased glasshouse were detected on inoculated plants. C. ilicicola was reisolated from the artificially infected tissues. No symptoms were detected on the control plants. Nucleotide sequences of the internal transcribed spacer (ITS) regions of the nrDNA operon and the partial histone H3 gene were determined for derived strain CPC 16334 as described previously (1,3). The ITS sequence (GenBank Accession No. GU057378) matched 100% (644/644 bp) with the sequence of C. ilicicola strain CBS 463.76 (GenBank AF493963) and the histone H3 sequence (GenBank GU057379) matched 99% (456/458 bp; due to two versus three AC repeats in the sequence) with that of C. ilicicola strain CBS 112217 (GenBank AY725686). To our knowledge, this is the first report of Calonectria and Cylindrocladium genera and the disease caused by C. ilicicola from Iran.

References: (1) R. Cheewangkoon et al. Persoonia 23:55, 2009. (2) P. W. Crous and M. J. Wingfield. Mycotaxon 51:341, 1994. (3) P. W. Crous et al. Stud. Mycol. 50:415, 2004.