bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetoelectric coupling in Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 thin films deposited on Pt/TiO2/SiO2/Si substrate
Authors: Cibert C. , Zhu J. , Poullain G. , Bouregba R. , More-Chevalier J. , Pautrat A.
Published: January 2013

Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 (Terfenol-D/Pt/PZT) thin films were sputtered on Pt/TiO2/SiO2/Si substrate. PZT and Terfenol-D layers were chosen for their large piezoelectric and magnetostrictive coefficients, respectively. 4%–5% magnetocapacitance has been measured on a Terfenol-D/Pt/PZT stack at room temperature. A magnetoelectric (ME) voltage coefficient of 150 mV/cm Oe was obtained at low dc magnetic field out of mechanical resonance. This work demonstrates the possibility to achieve ME effect in integrated devices involving Terfenol-D and PZT thin films providing that the diffusion, which may occur between both active layers is reduced using an intermediate layer.
First-principles study of electronic structures and photocatalytic activity of low-Miller-index surfaces of ZnO
Authors: Zhang Haifeng , Lu Shixiang , Xu Wenguo , Yuan Feng
Published: January 2013

First-principles calculations have been performed to investigate the electronic structures and optical properties of the main low-Miller-index surfaces of ZnO: nonpolar (101¯0) and (112¯0) surfaces as well as polar (0001)-Zn and (0001¯)-O surfaces. According to the structure optimization results, there are similar relaxation behaviors for the (101¯0) and (112¯0) surfaces, both with a strong tilting of the surface Zn-O dimers and an obvious contraction of the surface bonds. For the polar surfaces, the surface double layers both tend to relax inwards, but the largest relaxation is found on the (0001¯)-O surfaces. The calculated band gaps are 0.56, 0.89, 0.21, and 0.71 eV for (101¯0), (112¯0), (0001)-Zn and (0001¯)-O surfaces, respectively. For the nonpolar (101¯0) and 112¯0 surfaces, the Fermi levels locate at the valence band maximum, which are similar to that of bulk ZnO. The surface states in the conduction band lead to the increased Fermi level and cause the n-type conduction behavior for (0001)-Zn surface. For the (0001¯)-O surface, the Fermi level shifts down a little into the valence band, leading to the p-type conduction behavior. From the optical properties calculations, absorption regions of all the four surfaces are quite wide and the main absorption peaks locate in the UV region. For the (0001)-Zn surface, it has the strongest absorptions in the near UV-light range and a remarkable red-shift phenomenon of the absorption edge. This indicates that (0001)-Zn surface has the highest photocatalytic activity among the four surfaces as the low excitation energy is required theoretically. The computed results are in accordance with the experimental observations.
Investigation of an ion-ion hybrid Alfvén wave resonator
Authors: Vincena S. T. , Farmer W. A. , Maggs J. E. , Morales G. J.
Published: January 2013

A theoretical and experimental investigation is made of a wave resonator based on the concept of wave reflection along the confinement magnetic field at a spatial location where the wave frequency matches the local value of the ion-ion hybrid frequency. Such a situation can be realized by shear Alfvén waves in a magnetized plasma with two ion species because this mode has zero parallel group velocity and experiences a cut-off at the ion-ion hybrid frequency. Since the ion-ion hybrid frequency is proportional to the magnetic field, it is expected that a magnetic well configuration in a two-ion plasma can result in an Alfvén wave resonator. Such a concept has been proposed in various space plasma studies and could have relevance to mirror and tokamak fusion devices. This study demonstrates such a resonator in a controlled laboratory experiment using a H+-He+ mixture. The resonator response is investigated by launching monochromatic waves and impulses from a magnetic loop antenna. The observed frequency spectra are found to agree with predictions of a theoretical model of trapped eigenmodes.
Korteweg de Vries Burgers equation in multi-ion and pair-ion plasmas with Lorentzian electrons
Authors: Hussain S. , Akhtar N.
Published: January 2013

Korteweg de Vries Burgers equation for multi-ion and pair-ion plasmas has been derived using reductive perturbation technique. The kinematic viscosities of both positive and negative ions are taken into account. Generalized Lorentzian distribution is assumed for the electron component, accounting for deviation from Maxwellian equilibrium, parametrized via a real parameter κ. The modification in the strength of shock structure is presented. A comprehensive comparison between the profiles of shock wave structure in multi-ion and pair-ion plasmas, (for the Maxwellian electrons to Lorentzian electrons), is discussed.
A microscopic study of strongly plasmonic Au and Ag island thin films
Authors: Pavaskar Prathamesh , Hsu I-Kai , Theiss Jesse , Hsuan Hung Wei , Cronin Stephen B.
Published: January 2013

Thin Au and Ag evaporated films (∼5 nm) are known to form island-like growth, which exhibit a strong plasmonic response under visible illumination. In this work, evaporated thin films are imaged with high resolution transmission electron microscopy, to reveal the structure of the semicontinuous metal island film with sub-nm resolution. The electric field distributions and the absorption spectra of these semicontinuous island film geometries are then simulated numerically using the finite difference time domain method and compared with the experimentally measured absorption spectra. We find surface enhanced Raman scattering (SERS) enhancement factors as high as 108 in the regions of small gaps (≤2 nm), which dominate the electromagnetic response of these films. The small gap enhancement is further substantiated by a statistical analysis of the electric field intensity as a function of the nanogap size. Areal SERS enhancement factors of 4.2 × 104 are obtained for these films. These plasmonic films can also enhance the performance of photocatalytic and photovoltaic phenomena, through near-field coupling. For TiO2 photocatalysis, we calculate enhancement factors of 16 and 19 for Au and Ag, respectively. We study the effect of annealing on these films, which results in a large reduction in electric field strength due to increased nanoparticle spacing.
Scattering due to anisotropy of ellipsoid quantum dots in GaAs/InGaAs single quantum well
Authors: Jin Dong-Dong , Jiang Chao , Li Guo-Dong , Zhang Liu-Wan , Yang Tao , Liu Xiang-Lin , Yang Shao-Yan , Zhu Qin-Sheng , Wang Zhan-Guo
Published: January 2013

We suggest a new theoretical model to study the anisotropic scattering effect of the elongated quantum dots embedded in the GaAs/InGaAs double hetero-junction quantum well on the two-dimensional electron gas (2DEG). The elongated quantum dot (QD) with geometry which differs from ball-shaped quantum dot having isotropic cross section is assumed to be ellipsoid in the present calculation. The results show that the scattering in the direction parallel to the ellipsoid orientation (having small cross section) is weaker than that in the direction perpendicular to the ellipsoid orientation (having larger cross section) for the elongated QD when the mobile 2DEG is confined within the channel plane.
On the dynamics of Cu ions injection into low-k nanoporous materials under oscillating applied fields
Authors: Borja Juan , Plawsky Joel. L. , Lu T.-M. , Gill William N.
Published: January 2013

Cu injection into low-k dielectrics was studied using oscillating bipolar field experiments coupled with a mass transport model. Cu/SiCOH/Si structures were stressed using an oscillating square bipolar applied field at 200 °C. Breakdown was defined experimentally as the time it takes for the leakage current to exceed 1 × 10−5 A under given stress conditions. Time to failure was found to depend on field oscillating frequency and amplitude of the applied field. It was determined that ion solubility primarily affects the magnitude of lifetime enhancement, while mobility affects its onset in the frequency domain. Overtime, the local field generated by the accumulation of Cu ions during bias temperature stress resists the action of the oscillating field thus inhibiting the ability to sweep ions from cathode to anode through reversal of the applied field and thereby limits the observed lifetime enhancement. Predictions from the model match trends for experimental data involving transport of Cu ions into SiCOH.
Modeling and characterization of dielectrophoretically structured piezoelectric composites using piezoceramic particle inclusions with high aspect ratios
Authors: van den Ende D. A. , Maier R. A. , van Neer P. L. M. J. , van der Zwaag S. , Randall C. A. , Groen W. A.
Published: January 2013

In this work, the piezoelectric properties at high electric fields of dielectrophoretically aligned PZT—polymer composites containing high aspect ratio particles (such as short fibers) are presented. Polarization and strain as a function of electric field are evaluated. The properties of the composites are compared to those of PZT-polymer composites with equiaxed particles, continuous PZT fiber-polymer composites, and bulk PZT ceramics. From high-field polarization and strain measurements, the effective field dependent permittivity and piezoelectric charge constant in the poling direction are determined for dielectrophoresis structured PZT-polymer composites, continuous PZT fiber-polymer composites, and bulk PZT ceramics. The changes in dielectric properties of the inclusions and the matrix at high fields influence the dielectric and piezoelectric properties of the composites. It is found that the permittivity and piezoelectric charge constants increase towards a maximum at an applied field of around 2.5-5 kV/mm. The electric field at which the maximum occurs depends on the aspect ratio and degree of alignment of the inclusions. Experimental values of d33 at low and high applied fields are compared to a model describing the composites as a continuous polymer matrix containing PZT particles of various aspect ratios arranged into chains. Thickness mode coupling factors were determined from measured impedance data using fitted equivalent circuit model simulations. The relatively high piezoelectric strain constants, voltage constants, and thickness coupling factors indicate that such aligned short fiber composites could be useful as flexible large area transducers.
Comment on “Laser controlled magnetism in hydrogenated fullerene films” [J. Appl. Phys. 109, 083941 (2011)]
Authors: Talyzin A.
Published: January 2013

Hydrogenation of C60 films with formation of single hydrogen adduct reported by Makarova et al. [J. Appl. Phys. 109, 083941 (2011); Phys. Status Solidi B 246, 2778 (2009)] was supported only by several features found in Raman spectra of treated samples. However, no spectra were shown for untreated samples. Data shown in this comment prove that all Raman peaks assigned by Makarova et al. [J. Appl. Phys. 109, 083941 (2011); Phys. Status Solidi B 246, 2778 (2009)] to effects of hydrogenation can be found in spectra of pristine untreated commercial C60 powder. These peaks represent some second order vibrations of C60 as well as some possible solvent impurities. Therefore, all magnetic effects reported in this study should be assigned to unknown effects but not necessarily to hydrogenation.
Magnetization reversal asymmetry in [Co/Pt]/CoFe/IrMn multilayers with enhanced perpendicular exchange bias
Authors: Wu Qiong , He Wei , Liu Hao-Liang , Liu Yi-fan , Cai Jian-Wang , Cheng Zhao-Hua
Published: January 2013

The magnetization reversal of perpendicular exchange biased [Co/Pt]/Co60Fe40/IrMn and [Co/Pt]/Co/IrMn multilayers was investigated by time-resolved surface magneto-optical Kerr effect and Kerr microscopy. Compared with the nearly symmetric reversal of the [Co/Pt]/Co/IrMn with a smaller exchange bias field, significantly asymmetric domain evolution in the [Co/Pt]/Co60Fe40/IrMn with a larger exchange bias field was directly observed by Kerr microscopy. The asymmetric magnetization reversal is discussed in terms of the average thermally activated energy barriers as well as the dispersions of the barriers. The substitution of the interfacial Co60Fe40 layer for Co layer results in an enhancement of the interfacial exchange coupling εint and absolute dispersion of interfacial exchange coupling, σεint, and consequently increases the exchange bias field and reversal asymmetry.
Radiation effects and tolerance mechanism in β-eucryptite
Authors: Narayanan Badri , Reimanis Ivar E. , Huang Hanchen , Ciobanu Cristian V.
Published: January 2013

Previous studies on Li-silicates have shown that these materials are resistant to radiation damage even in extreme physical and chemical environments, and are thus promising solid-state breeder materials in fusion reactors. Here, we focus on β-eucryptite as a member of Li-Al silicate class of ceramics with potential for nuclear applications, and study the atomic-scale processes induced by radiation. Using molecular dynamics simulations based on a reactive force field, we have found that upon radiation dosage of 0.21 displacements-per-atom or less, the structure largely retains its long-range order while exhibiting (a) disordering of the Li atoms, (b) distortion of the Si and Al tetrahedra defined as the change in their oxygen-coordination number, and (c) tilting of the Si and Al tetrahedra with respect to one another. We find that Si tetrahedra that distort to SiO3 during exposure to radiation recover significantly upon thermal relaxation, and provide the mechanism for this recovery. This mechanism consists in the tilting of AlO5 polyhedra formed upon exposure so as to satisfy the oxygen-coordination of distorted Si tetrahedra. Doubling the dosage results in a significant increase of the concentration of Si-Al antisite defects, which renders the tolerance mechanism inefficient and leads to amorphization.
Transport critical current measurement apparatus using liquid nitrogen cooled high-Tc superconducting magnet with variable temperature insert
Authors: Nishijima G. , Kitaguchi H. , Tshuchiya Y. , Nishimura T. , Kato T.
Published: January 2013

We have developed an apparatus to investigate transport critical current (Ic) as a function of magnetic field and temperature using only liquid nitrogen. The apparatus consists of a (Bi,Pb)2Sr2Ca2Cu3O10 (Bi-2223) superconducting magnet, an outer dewar, and a variable temperature insert (VTI). The magnet, which is operated in depressurized liquid nitrogen, generates magnetic field up to 1.26 T. The sample is also immersed in liquid nitrogen. The pressure in the VTI is controlled from 0.02 to 0.3 MPa, which corresponds to temperature ranging from 66 to 88 K. We have confirmed the long-term stable operation of the Bi-2223 magnet at 1 T. The temperature stability of the sample at high transport current was also demonstrated. The apparatus provides easy-operating Ic measurement environment for a high-Tc superconductor up to 500 A in magnetic fields up to 1 T and in temperatures ranging from 66 to 88 K.
Effects of GaAs(Sb) cladding layers on InAs/AlAsSb quantum dots
Authors: Sun Meng , Simmonds Paul J. , Babu Laghumavarapu Ramesh , Lin Andrew , Reyner Charles J. , Duan Hsin-Sheng , Liang Baolai , Huffaker Diana L.
Published: January 2013

The structural and optical properties of InAs self-assembled quantum dots buried in AlAs0.56Sb0.44 barriers can be controlled using GaAs1−xSbx cladding layers. These cladding layers allow us to manage the amount of Sb immediately underneath and above the InAs quantum dots. The optimal cladding scheme has a GaAs layer beneath the InAs, and a GaAs0.95Sb0.05 layer above. This scheme results in improved dot morphology and significantly increased photoluminescence (PL) intensity. Both power-dependent and time-resolved photoluminescence confirm that the quantum dots have type-II band alignment. Enhanced carrier lifetimes in this quantum dot system show great potential for application in intermediate band solar cells.
Adsorption capacity of H2O, NH3, CO, and NO2 on the pristine graphene
Authors: Lin Xianqing , Ni Jun , Fang Chao
Published: January 2013

First-principles together with statistical mechanics calculations have been performed to study the adsorption behavior of H2O, NH3, CO, and NO2 on the pristine graphene. In the first-principles calculations, we find that the most recent van der Waals (vdW) density functional vdW-DF2 gives even larger binding energies (Eb) that those obtained with the local density approximation, indicating vdW-DF2 may be inappropriate for describing the interaction between these molecules and graphene. With the potential energy curves of the molecules on graphene calculated by the density functional theory, the adsorption capacity (n) of the molecules on the pristine graphene is calculated with the statistical mechanics method. NO2 has the largest n of the order of 108 cm−2 among the four molecules on graphene at room temperature and concentration of 1.0 ppm, but still smaller by almost two order than that on graphene devices estimated from the experimental results. This is probably due to the strong binding of NO2 to the graphene edges with terminating oxygen atoms with Eb as large as 1.0 eV. The calculations of the adsorption capacity of small polar molecules on the pristine graphene and comparison with the experimental values may contribute to the understanding of the mechanism and designing of graphene based gas sensors.
Effect of mechanical strain on magnetic properties of flexible exchange biased FeGa/IrMn heterostructures
Authors: Zhang Xiaoshan , Zhan Qingfeng , Dai Guohong , Liu Yiwei , Zuo Zhenghu , Yang Huali , Chen Bin , Li Run-Wei
Published: January 2013

We have fabricated flexible exchange biased heterostructures with magnetostrictive Fe81Ga19 alloy as the ferromagnetic layer and Ir20Mn80 as the antiferromagnetic layer on polyethylene terephthalate substrates. The mechanical strain can modify both the strength and the orientation of the uniaxial anisotropy, giving rise to the switching between the easy and hard magnetization directions. Different from the previously reported works on rigid exchange biased systems, a drastic decrease in exchange bias field was observed under a compressive strain with magnetic field parallel to the pinning direction, but only a slightly decrease was shown under a tensile strain. Based on a Stoner-Wohlfarth model calculation, we suggested that the distributions of both ferromagnetic and antiferromagnetic anisotropies be the key to induce the mechanically tunable exchange bias.
Detection of Dynabeads using a micro-electro-mechanical-systems fluxgate sensor
Authors: Lei Jian , Wang Tao , Lei Chong , Zhou Yong
Published: January 2013

This paper presents an approach to detect the presence of Dynabeads with a system based on a micro fluxgate sensor fabricated by micro-electro-mechanical systems technology. Due to the excellent performance of the micro fluxgate sensor, the detection system exhibited many advantages, such as lower minimum detectable limit, small weight, and low power consumption. Experimental results show that, applied an external magnetic field in a range of 430 μT to 600 μT, Dynabeads with a concentration as low as 0.1 μg/ml can be detected by this system. Moreover, the detection system could give an approximate quantitation to the magnetic beads.
Surface plasmon modulation induced by a direct-current electric field into gallium nitride thin film grown on Si(111) substrate
Authors: Stolz Arnaud , Ko Suk-Min , Patriarche Gilles , Dogheche Elhadj , Cho Yong-Hoon , Decoster Didier
Published: January 2013

We report here the experimental results on a field effect refractive index change into gallium nitride (GaN) structures. This effect is characterized through the common prism-coupling technique with the application of a vertical direct-current electric field. Surface plasmon propagation was used to increase the sensitivity of the electro-optic measurements. We have obtained a large refractive index variation for GaN epilayer, around 1.4×10−2 at 1.55μm wavelength. In order to understand the origin of the index modulation, we have conducted a scanning transmission electron microscopy analysis and discussed the influence of threading dislocations density acting as traps and thermo-optic effect. According to recent works, we observed experimentally the optical response of a non-linear electro-optic effect on GaN on Si(111) substrate and estimated a Kerr coefficient of about 2.14×10−16m2 V−2.
Note: A three-dimensional calibration device for the confocal microscope
Authors: Jensen K. E. , Weitz D. A. , Spaepen F.
Published: January 2013

Modern confocal microscopes enable high-precision measurement in three dimensions by collecting stacks of 2D (x–y) images that can be assembled digitally into a 3D image. It is difficult, however, to ensure position accuracy, particularly along the optical (z) axis where scanning is performed by a different physical mechanism than in x–y. We describe a simple device to calibrate simultaneously the x, y, and z pixel-to-micrometer conversion factors for a confocal microscope. By taking a known 2D pattern and positioning it at a precise angle with respect to the microscope axes, we created a 3D reference standard. The device is straightforward to construct and easy to use.
Effects of the growth and the charge of carbon nanoparticles on direct current discharges
Authors: Arnas C. , Michau A. , Lombardi G. , Couëdel L. , Kumar K Kishor
Published: January 2013

The formation of fine particles in plasmas from sputtered carbon atoms and the consequences of their growth and charging mechanisms on sputtering DC discharges were investigated. Experiments were performed with a constant discharge current so that the coupling between the plasma and two successive generations of nanoparticles were studied through the evolution of the discharge voltage, proportional to the ionization rate and also through the plasma emission. The consequences of the formation of negative ionic molecular precursors of the first particle generation were established as well as the effects of a redistribution of the nanoparticle cloud in the inter-electrode gap, not similar to the void effects usually observed in RF discharges. The cathode heating during the sputtering mechanism was also considered to explain partly the evolution of the discharge voltage and the plasma emission during the growth of the second nanoparticle generation.
Effect of multiple scattering on Cerenkov radiation from energetic electrons
Authors: Zheng Jian
Published: January 2013

Cerenkov radiation can be used as a diagnostic tool to study energetic electrons generated in ultra-intense laser matter interactions. However, electrons suffer scattering with nuclei as they move in a medium. In this article, we theoretically study the effect of multiple scattering on Cerenkov radiation, and obtain analytical formulas under some circumstances. The results show that when the speed of an energetic electron is not close to the light speed in the medium, Cerenkov radiation is just slightly decreased due to multiple scattering. In the case that the electron speed is very close to the light speed in the medium, the effect of multiple scattering becomes significant, and the radiation is dominated by bremsstrahlung.
Heterojunction photodiode fabricated from multiwalled carbon nanotube/ZnO nanowire/p-silicon composite structure
Authors: Shao Dali , Yu Mingpeng , Lian Jie , Sawyer Shayla
Published: January 2013

A heterojunction photodiode was fabricated from multiwalled carbon nanotubes (MWCNTs)/ZnO nanowires/p-Si (100) substrate composite structure. The heterojunction photodiode demonstrated a faster transient response and higher responsivity than the reference sample without deposition of MWCNTs, which is attributed to improved carrier collection and transport efficiency through the MWCNTs network. The high photoresponsivities of the devices are explained in terms of operation as a hybrid of photodiode and photoconductor modes. The spectral response of the devices showed dependence on voltage polarity and is attributed to the high valance band offset in the interfacial region of ZnO and p-Si substrate.
Transient characterization of the electroforming process in TiO2 based resistive switching devices
Authors: Noman Mohammad , Sharma Abhishek A. , Meng Lu Yi , Skowronski Marek , Salvador Paul A. , Bain James A.
Published: January 2013

The transient electroforming process of TiO2-based resistive switching devices is investigated using a pulsed voltage method, and the electroforming time is found to vary from 10−8 s to 10−1 s as function of pulse magnitude (3–8 V) and ambient temperature (25–100 °C). Pulsed experiments and thermal simulations reveal that Joule self-heating has a significant effect on the electroforming dynamics, specially for electroforming voltages above 5.5 V where there is little dependence on ambient temperature and the electroforming time (10–100 ns) is much shorter than the device thermal time constant (≈2 μs).
Communication: Structure of magnetic lanthanide clusters from far-IR spectroscopy: ${\rm Tb}_n^+$ Tb n+ (n = 5−9)
Authors: Bowlan John , Harding Dan J. , Jalink Jeroen , Kirilyuk Andrei , Meijer Gerard , Fielicke André
Published: January 2013

Small lanthanide clusters have interesting magnetic properties, but their structures are unknown. We have identified the structures of small terbium cluster cations \documentclass[12pt]{minimal}\begin{document}${\rm Tb}_{n}^{+}$\end{document} Tb n+ (n = 5−9) in the gas phase by analysis of their vibrational spectra. The spectra have been measured via IR multiple photon dissociation of their complexes with Ar atoms in the 50−250 cm−1 range with an infrared free electron laser. Density functional theory calculations using a 4f-in-core effective core potential (ECP) accurately reproduce the experimental far-IR spectra. The ECP corresponds to a 4f 85d16s2 trivalent configuration of terbium. The assigned structures are similar to those observed in several other transition metal systems. From this, we conclude that the bonding in Tb clusters is through the interactions between the 5d and 6s electrons, and that the 4f electrons have only an indirect effect on the cluster structures.
Experimental study of the performance of solar still using a reciprocating intermittent spray feeding system
Authors: Kabeel A. E. , Elkenany E. A. , Hawam O. M.
Published: January 2013

One of the most important parameters in desalination using solar still is minimizing the flow rate of saline water feeding. Consequently, the saline water depth could decide the performance of the solar still. Some of the research works incorporated those parameters into consideration but in a limited scale. An experimental investigation on a stepped solar still with intermittent spray feeding system using flash evaporation was studied. That procedure was executed by feeding the saline water into the still through a controlled transverse reciprocating spray system on the form of fine droplets. This technique helps on the uniform spread of droplets on the top surface of a stepped-absorber solar still in an intermittent process. The thin film of the saline water has many significant advantages on the still performance due to its very low thermal inertia. The present approach has undergone a systematic study to optimize its performance. The still was tested at 250 rpm motor speed and at 15.606 l/h and 9.333 l/h rates of saline water spray flow. The spray frequency was 5, 4, 3, 2.5 spray per hour. Optimum operating conditions were identified. An accumulated productivity of 5.519 l/m2 over only 10 h with efficiency of 65.11% was obtained.
Temperature controlled c axis elongated low symmetry phase BiFeO3 thin film on STO substrate
Authors: Ren Peng , Khuen Cho Soon , Liu Peng , You Lu , Zou Xi , Wang Baomin , Wang Junling , Wang Lan
Published: January 2013

BiFeO3 thin films with a mixture of tunable R-like and c axis elongated low symmetry phase (T-like phase) are fabricated on STO (001) substrate through controlling of the substrate temperature. Almost pure T-like phase can be grown on STO substrate at 600°C. Comparing with the situations on LAO (001), it is found that, strains from the LAO substrate may be the only reason that induces the T-like phase at higher temperatures. At lower temperatures, the island growth induced strains alone can also generate T-like phase on STO substrate.
Irano-Russian Trade and Travel: Haj Muhammad Hassan Amin al-Zarb and Others
Authors: Mahdavi Shireen
Published: January 2013

Contacts between Russians and Persians have a long history going back to 1592 during the reign of the Safavid dynasty (1501–1736). However, the impact of Russia upon Persia was only felt as a result of military defeats in 1813 and 1828. In nineteenth century Persia there were many geographical obstacles which prevented foreigners including Russians from trading with Persia. This situation changed with the Treaty of Turkmanchai and its commercial protocol which gave Russian merchants special benefits and advantages. Consequently, by the 1860s Russian steamships started postal, passenger and cargo service from Baku to Persian Caspian ports and railheads advanced through the Caucasus to Tiflis. Persia traded with Russia on a much larger scale than with any other country. One of the Persian merchants who traded extensively with or through Russia to Europe was Haj Muhammad Hassan Amin al-Zarb (1834–98), the most prominent merchant of his time, and subsequently his son Haj Husayn Aqa Amin al-Zarb II. The article discusses Amin al-Zarb's trade and relations with Russia based upon unpublished material in the Amin al-Zarb archives in Tehran.
Outbreak of Fluoroquinolone-ResistantEscherichia coliInfections after Transrectal Ultrasound—Guided Biopsy of the Prostate
Authors: Dumford Donald , Suwantarat Nuntra , Bhasker Vineet , Kundrapu Sirisha , Zabarsky Trina F. , Drawz Paul , Zhu Hui , Donskey Curtis J.
Published: January 2013

Design.

We conducted an investigation after identifying a cluster of 4 serious infections following transrectal ultrasound–guided biopsy of the prostate (TRUBP) during a 2-month period.

Setting.

veterans Affairs medical center.

Patients.

Patients with urinary tract infection (UTI) after TRUBP and time-matched controls with no evidence of infection.

Methods.

The incidence of UTI within 30 days after TRUBP was calculated from 2002 through 2010. We evaluated the correlation between infection with fluoroquinolone-resistant gram-negative bacilli (GNB) and fluoroquinolone resistance in outpatientEscherichia coliurinary isolates and performed a case-control study to determine risk factors for infection with fluoroquinolone-resistant GNB. Processes for TRUBP prophylaxis, procedures, and equipment sterilization were reviewed.

Results.

An outbreak of UTI due to fluoroquinolone-resistantE. coliafter TRUBP began 2 years before the cluster was identified and was correlated with increasing fluoroquinolone resistance in outpatientE. coli. No deficiencies were identified in equipment processing or biopsy procedures. Fluoroquinolone-resistant E. coli UTI after TRUBP was independently associated with prior infection with fluoroquinolone-resistant GNB (adjusted odds ratio, 20.8;P= .005). A prediction rule including prior UTI, hospitalization in the past year, and previous infection with fluoroquinolone-resistant GNB identified only 17 (49%) of 35 cases.

Conclusions.

The outbreak of fluoroquinolone-resistantE. coliinfections after TRUBP closely paralleled rising rates of fluoroquinolone resistance among outpatientE. coliisolates. The delayed detection of the outbreak and the absence of sensitive predictors of infection suggest that active surveillance for infection after TRUBP is necessary in the context of increasing fluoroquinolone resistance in the United States.
Decompositions of looped co-𝐻-spaces
Authors: Grbić J. , Theriault S. , Wu J.
Published: January 2013

We prove two homotopy decomposition theorems for the loops on simply-connected co-

H
H

-spaces, including a generalization of the Hilton-Milnor Theorem. Several examples are given.
Single population and common natal origin for Adriatic Scomber scombrus stocks: evidence from an integrated approach
Authors: Papetti Chiara , Di Franco Antonio , Zane Lorenzo , Guidetti Paolo , De Simone Valeria , Spizzotin Marianna , Zorica Barbara , Čikeš Keč Vanja , Mazzoldi Carlotta
Published: January 2013

Papetti, C., Di Franco, A., Zane, L., Guidetti, P., De Simone, V., Spizzotin, M., Zorica, B., Čikeš Keč, V. and Mazzoldi, C. 2013. Single population and common natal origin for Adriatic Scomber scombrus stocks: evidence from an integrated approach – ICES Journal of Marine Science, 70: 387–398. In order to implement proper fishery management strategies aimed at avoiding stock declines, information about connectivity among stocks and populations is critically required. In this perspective, the present study investigated population structure of the Atlantic mackerel Scomber scombrus in the northern–central Adriatic Sea by integrating multiple approaches (analysis of fisheries data, population genetics, and otolith chemistry). Monthly data of fishery landings indicate a latitudinal trend along the western Adriatic coast, with Atlantic mackerel disappearing from the northern waters in winter, corresponding to the reproductive season. Population genetic analyses by genotyping of eight microsatellites clearly point to the presence of a single panmictic population in the northern–central Adriatic Sea. Otolith cores of samples from the northern–central Adriatic were chemically homogeneous, suggesting a common spawning ground. These results strongly suggest that Atlantic mackerel perform an autumn–winter migration in the northern–central Adriatic Sea, from the northern to the central sector, to reach a single spawning ground, and that a single population is present in this area. Considering that S. scombrus has shown a marked decline in the last 40 years in the Adriatic, this study highlights a potential high vulnerability to collapse by overfishing for the Atlantic mackerel stocks in this geographic area.
Spatial and temporal variability of the Pacific saury (Cololabis saira) distribution in the northwestern Pacific Ocean
Authors: Tseng Chen-Te , Su Nan-Jay , Sun Chi-Lu , Punt André E. , Yeh Su-Zan , Liu Don-Chung , Su Wei-Cheng
Published: January 2013

Tseng, C-T., Su, N-J., Sun, C-L., Punt, A. E., Yeh, S-Z., Liu, D-C., and Su, W-C. 2013. Spatial and temporal variability of the Pacific saury (Cololabis saira) distribution in the northwestern Pacific Ocean. – ICES Journal of Marine Science, 70: 991–999. Logbook data for the Taiwanese Pacific saury fishery and multi-sensor satellite images for 2006–2010 were used to characterize the habitat of Pacific saury (Cololabis saira) in the northwestern Pacific (NWP). An empirical cumulative distribution function (ECDF) approach identified that high cpue (catch per unit of effort) of Pacific saury occurred when sea surface temperature (SST) ranged from 14 to 16°C, chlorophyll-a concentration (Chl a) ranged from 0.4 to 0.6 mg m−3, and net primary production (NPP) ranged from 600 to 800 mg C m−2 d−1. A generalized additive model (GAM) and spatial non-stationary geographically weighted regression (GWR) were applied to predict the habitats of Pacific saury in the NWP. The spatial distributions of Pacific saury in the NWP estimated using the two approaches were similar and matched the nominal cpue distributions and those inferred from preferred habitat ranges based on ECDF. The density of Pacific saury is higher in coastal waters close to the island of Hokkaido and near the southern Kuril Islands than in the open sea. SST, Chl a, and NPP were substantially higher in the fishing grounds for Pacific saury during the main fishing season (September and October), corresponding to a high cpue for Pacific saury (23.1 t fishing day−1). The GAM explained more variability in spatial distribution (35.7%) than GWR (20.5%) VGPM (Vertically Generalized Production Model). Results derived from this study could improve our understanding of Pacific saury habitat distributions, which could be used to forecast fishing grounds and to develop fishery management advice based on oceanographic conditions that might be impacted by climate change.
Phenotypic, Molecular, and Pathological Characterization of Colletotrichum acutatum Associated with Andean Lupine and Tamarillo in the Ecuadorian Andes
Authors: Falconí César E. , Visser Richard G. F. , van Heusden Adriaan W.
Published: January 2013

Anthracnose is a serious problem of both Andean lupine and tamarillo in Ecuador. Morphological features, internal transcribed spacer (ITS) sequences, and host specificity were used to characterize Colletotrichum isolates from lupine and tamarillo. Based on phenotypic and molecular characterization, the causal agent of anthracnose on both hosts was Colletotrichum acutatum. All isolates were identified in a C. acutatum-specific polymerase chain reaction assay. Colony diameter, conidia shape, and insensitivity to benomyl also placed isolates from both hosts in the C. acutatum group. However, a detailed analysis of the ITS sequences placed the lupine and tamarillo isolates from the Ecuadorian Andean zone in two clades, with both lupine and tamarillo isolates in each clade. C. acutatum isolates from Andean lupine were distinct from other C. acutatum isolates on lupine around the world. In cross-infection studies, the diameter of lesions produced by isolates from each host was compared on the main stem of two tamarillo and three lupine cultivars. Some isolates produced larger lesions on the host from which they were isolated but others showed similar aggressiveness on their alternate host. Isolates from both hosts were biotrophic on lupine stems, producing little necrosis and abundant sporulation whereas, on tamarillo stems, they produced dark lesions with few conidia. The collection of C. acutatum isolates from lupine and tamarillo provides interesting material for the study quantitative host adaptation.
Diversity of Rhizoctonia spp. Causing Foliar Blight on Brachiaria in Colombia and Evaluation of Brachiaria Genotypes for Foliar Blight Resistance
Authors: Alvarez Elizabeth , Latorre Michael , Bonilla Ximena , Sotelo Guillermo , Miles John W.
Published: January 2013

Up to 50% of Brachiaria production in the tropics is affected by foliar blight caused by Rhizoctonia spp. Monothallic isolates of Rhizoctonia (n = 147) were cultured from different Brachiaria genotypes in Colombia and morphologically characterized and evaluated in pathogenicity trials in the greenhouse. Based on restriction fragment length polymorphism of the internal transcribed spacer region, 101 of the isolates were identified as Rhizoctonia solani anastomosis group (AG)-1 IA and were multinucleated, with high growth rate, brown mycelium, and high virulence; and 46 isolates were identified as Rhizoctonia sp. AG-D and were binucleated, with low growth rate, white mycelium, and lower virulence on the Brachiaria genotypes tested. The Rhizoctonia isolates also showed variation according to geographic origin, with R. solani AG-1 IA prevalent in warm lowland areas and Rhizoctonia sp. AG-D occurring in cooler areas. Ten Brachiaria genotypes were challenged with different Rhizoctonia isolates and resistant reactions were seen in three of these genotypes, including Brachiaria hybrid (International Center for Tropical Agriculture [CIAT] 36062), Brachiaria brizantha ‘Marandú’ (CIAT 6294), and Brachiaria hybrid ‘Mulato II’ (CIAT 36087). These results will contribute to a greater understanding of the interaction of diverse Rhizoctonia isolates on different Brachiaria genotypes, supporting improvement of Brachiaria spp. for disease resistance.
Effect of Fungicide Seed Treatments, Cultivars, and Soils on Soybean Stand Establishment
Authors: Urrea K. , Rupe J. C. , Rothrock C. S.
Published: January 2013

Seedling diseases are one of the major production problems for soybean. The primary control of soybean seedling diseases is by fungicide seed treatments but comparisons of seed treatments are difficult because stand responses are often erratic in the field. The objective of this study was to determine the efficacy of soybean fungicide seed treatments in naturally infested soils under controlled environments at three temperatures. Seed of three soybean cultivars were treated with six fungicide treatments or not treated and planted in two soil types collected from two fields in April, May, and June 2008 and 2009. Tests were conducted in growth chambers at 21°C (April planting), 25°C (May planting), or 28°C (June planting). Stands were determined when at least 25% of the seedlings reached the V4 growth stage. Seed treatments improved stands at all three temperatures, in both soils, and in both years. In general, the broad-spectrum fungicides trifloxystrobin + metalaxyl and mefenoxam + fludioxonil + azoxystrobin resulted in the highest stands. The selective fungicide treatments metalaxyl and pentachloronitrobenzene + carboxin were effective at all three temperatures, implying that Pythium spp. and Rhizoctonia solani, respectively, were involved in seedling disease and active over a range of temperatures. The efficacy of fungicides was not consistently associated with the cultivars used in this study.
First Report of Calonectria Leaf Spot on Ohelo in Hawaii
Authors: Keith L. M. , Matsumoto T. K. , Zee F. T. P.
Published: January 2013

Ohelo, Vaccinium reticulatum (Smith), is an endemic Hawaiian shrub, less than 1 m tall, which grows between 640 and 3,700 m elevation on disturbed volcanic sites on the islands of Maui and Hawaii (3). Ohelo berries are made into jams, jellies, and pie filling and are also a food source for the endemic nene goose, the state bird of Hawaii (3). In the summer of 2010, Ohelo berry plants grown in a greenhouse nursery located in Hilo, Hawaii, exhibited severe disease symptoms including leaf spots, stem lesions, and defoliation. The leaf spots appeared rapidly and were fairly severe. Subsequent field surveys of areas of naturally growing Ohelo within Hawaii Volcanoes National Park and along the roadside of Saddle Road were negative. An anamorphic state of Cylindrocladium was consistently isolated from the diseased portions of plants on potato dextrose agar (PDA). To determine the species, single-conidial isolates of the fungus were cultured for 14 days at 25°C under 12 h of light/dark conditions. Conidia were produced on penicillately branched condiophores having a stipe extension of 101.5 to 231.3 × 1.9 to 3.5 μm, terminating in a narrowly clavate vesicle, 2.4 to 3.5 μm. Conidia were hyaline, cylindrical, rounded at both ends, straight, three septate, and 58.6 to 77.77 × 4.29 to 5.72 μm. The nucleotide sequence of the partial β-tubulin gene was determined for strain Vr1 and a BLAST analysis of the β-tubulin sequence (GenBank Accession No. JX852715) revealed 99% similarity (337/341 bp) with the sequence of Calonectria pseudocolhounii strain CMW27213 (HQ285789) (1). Based on morphology and molecular sequencing, the fungus was identified as Calonectria irrespective of the teleomorphic stage in accordance with Lombard et al. (2). Koch's postulates were fulfilled by spray inoculating eight Ohelo seedlings and eight Ohelo variety N06-7 (‘Kilauea’) plants with a spore suspension (105 conidia per ml) of one isolate of the pathogen 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 growth chamber at 25 ± 1°C and 90 to 95% relative humidity. Four plants were used as a control. After 5 to 7 days, foliar symptoms resembling those seen in the nursery were detected on inoculated plants; leaf drop was first observed after day 7. No symptoms were detected on the control plants. The Calonectria sp. was reisolated from the artificially infected tissues. To our knowledge, this is the first report of a Calonectria sp. causing disease on Ohelo berry in Hawaii.

References: (1) S. F. Chen et al. Persoonia 26:1, 2011. (2) L. Lombard et al. Stud. Mycol. 66:1, 2010. (3) F. Zee et al. F&N-16, May 2011.
First Report of a 16SrIX Group (Pigeon Pea Witches'-Broom) Phytoplasma Associated with Sesame Phyllody in Turkey
Authors: Catal M. , Ikten C. , Yol E. , Üstün R. , Uzun B.
Published: January 2013

Sesame (Sesamum indicum L.) is an important oilseed crops widely grown in the southern regions of Turkey. Sesame seeds are primarily used in production of tahini as well as a garnish on sweets and bakery products in the country. Sesame plants with phyllody disease symptoms have increasingly been observed in the fields of Antalya province since 2007. The disease incidence in these fields was found to range from 37 to 62% (2). Infected plants display a variety of the disease symptoms such as virescence, asymptomatic shoot proliferation, infertile flower formation, reduced leaf size, and thin and weak capsule development. Total genomic DNA was extracted from samples collected from symptomatic (10 plants) and asymptomatic healthy-looking plants (10 plants) using a CTAB method and amplified with universal primers P1/P7 and R16F2n/R16R2 in direct and nested PCR, respectively (1,3). Amplifications of the DNA from the symptomatic plants yielded a product of 1.8 kb in direct and 1.2 kb in nested PCR assays. No amplification was observed in symptomless plants of the same age and collected from the same fields. Amplicons were purified, cloned in a pTZ57R/T Vector, and sequenced using a Beckman Coulter 8000 CEQ Genetic Analysis System. Four aligned 16S rDNA sequences (1,845 bp) were found to be all identical and belonging to one species. One sequence was deposited in GenBank under the accession number KC139791. A BLAST similarity search revealed that the sequence shared 99% homology with the sequences of the members of 16SrIX group phytoplasmas, ‘Brassica rapa’ phyllody phytoplasma (HM559246.1) and Iranian Almond witches'-broom phytoplasma (DQ195209.1) available in GenBank. In addition, iPhyClassifier software (4) was employed to create a virtual RFLP profile. The analysis showed that the RFLP profile of the sesame phytoplasma 16S rDNA sequence is identical (a similarity coefficient of 1.00) to the profile of the 16Sr group IX phytoplasma reference sequence (Y16389). A phylogenetic tree was also constructed using the neighbor joining plot option of the Clustal X program. The sequence clustered together with 16SrIX group phytoplasmas. To our knowledge, this is the first report of a natural infection of sesame by a new phytoplasma species from the 16SrIX group in Turkey.

References: (1) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (2) C. Ikten et al. Phytopathogenic Mollicutes 1:101, 2011. (3) C. D. Smart et al. Appl. Environ. Microbiol. 62:2988, 1996. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.