bluuebunny/crossref_metadata_2025 huggingface dataset:
Shock compression response of a Zr-based bulk metallic glass up to 110 GPa
Authors: Xi Feng , Yu Yuying , Dai Chengda , Zhang Yi , Cai Lingcang
Published: October 2010

Shock wave compression experiments were conducted on a Zr-based bulk metallic glass (BMG, Zr51Ti5Ni10Cu25Al9 in atomic percent) up to 110 GPa. Time-resolved free-surface velocity profiles were measured in a shock stress range from 18 to 28 GPa with velocity interferometer techniques. The shock Hugoniot data in a shock stress range from 53 to 110 GPa were obtained by using electric pin techniques. The time-resolved wave profiles showed a distinct two-wave structure consisting of an elastic precursor followed by a plastic wave. Based on the obtained wave profiles, the Hugoniot elastic limits were determined to be 6.9 to 9.6 GPa. The shock wave velocity (Ds) vs. particle velocity (up) Hugoniot data in a shock stress range from 18 to 110 GPa were linearly fitted by Ds=(4.241±0.035)+(1.015±0.024)up. No evidence of phase transition was found in the performed shock experiments of the Zr-based BMG.
TiAlNiAu contacts for ultrathin AlN/GaN high electron mobility transistor structures
Authors: Zhou Lin , Chang C. Y. , Pearton S. J. , Ren F. , Dabiran Amir , Smith David. J.
Published: October 2010

The morphology of ultrathin AlN/GaN high electron mobility transistors without or with TiAlNiAu Ohmic contacts, and annealed from 750 to 950 °C, has been investigated using transmission electron microscopy and associated analytical techniques. After annealing, the contact surface roughness was degraded due to intermixing and phase separation of the metal layers. TiN contact inclusions (CIs) that had penetrated through the AlN layers into the underlying GaN layers along threading dislocations, were observed in all annealed samples. The CI density increased with increasing annealing temperature but the lowest specific contact resistivity was obtained for structures annealed at 850 °C. Annealing at 950 °C caused cracking on the contact metal surface. The AlN layers remained intact in dislocation-free areas of all samples. The relationship between annealing temperature, interfacial structure and contact resistance is also discussed.
Cohomology of line bundles: A computational algorithm
Authors: Blumenhagen Ralph , Jurke Benjamin , Rahn Thorsten , Roschy Helmut
Published: October 2010

We present an algorithm for computing line bundle valued cohomology classes over toric varieties. This is the basic starting point for computing massless modes in both heterotic and type IIB/F-theory compactifications, where the manifolds of interest are complete intersections of hypersurfaces in toric varieties supporting additional vector bundles.
Ion-acoustic nonlinear periodic waves in electron-positron-ion plasma
Authors: Chawla J. K. , Mishra M. K.
Published: October 2010

Ion-acoustic nonlinear periodic waves, namely, ion-acoustic cnoidal waves have been studied in electron-positron-ion plasma. Using reductive perturbation method and appropriate boundary condition for nonlinear periodic waves, the Korteweg–de Vries (KdV) equation is derived for the system. The cnoidal wave solution of the KdV equation is discussed in detail. It is found that the frequency of the cnoidal wave is a function of its amplitude. It is also found that the positron concentration modifies the properties of the ion-acoustic cnoidal waves. The existence regions for ion-acoustic cnoidal wave in the parameters space (p,σ), where p and σ are the positron concentration and temperature ratio of electron to positron, are discussed in detail. In the limiting case these ion-acoustic cnoidal waves reduce to the ion-acoustic soliton solutions. The effect of other parameters on the characteristics of the nonlinear periodic waves is also discussed.
Possible excitation of solitary electron holes in a laboratory plasma
Authors: Kar S. , Mukherjee S. , Ravi G. , Saxena Y. C.
Published: October 2010

Plasma response to a fast rising high positive voltage pulse is experimentally studied in a uniform and unmagnetized plasma. The pulse is applied to a metallic disk electrode immersed in a low pressure argon plasma (np∼109 cm−3 and Te∼0.5–2 eV) with the pulse magnitude U0⪢kTe/e, where Te is the electron temperature. Experiments have been carried out for various applied pulse widths τp ranging from less than 3fi−1 to greater than 3fi−1, where fi is the ion plasma frequency. For pulse widths less than 3fi−1, potential disturbances are observed to propagate in two opposite directions from a location different from the actual exciter (metal disk electrode), indicating the presence of a virtual source. For pulse widths equal or greater than 3fi−1, there is no indication of such virtual source. These disturbances propagate with two phase speeds, i.e., vp/ve=1.36±0.11 and 0.4±0.15, where ve is the electron thermal speed. It is also observed that by increasing plasma density, the speed of these disturbances increases, whereas the speed is independent of pulse magnitude. Analysis of these disturbances indicates the excitation of solitary electron holes.
Evidence of inverse bremsstrahlung in laser enhanced laser-induced plasma
Authors: Wiggins D. L. , Raynor C. T. , Johnson J. A.
Published: October 2010

Plasmas created by a Nd:yttrium aluminum garnet laser show systematic changes in local electron temperature when bathed by a continuous wave laser of increasing irradiance. By monitoring the local electron density, the laser light absorption coefficient, and the signal to noise ratio in neutral emissions, we explain the changes in electron temperature and signal to noise to be a consequence of inverse bremsstrahlung in this new system of laser enhanced laser-induced plasmas.
New developments in the diagnostics for the fusion products on JET in preparation for ITER (invited)
Authors: Murari A. , Angelone M. , Bonheure G. , Cecil E. , Craciunescu T. , Darrow D. , Edlington T. , Ericsson G. , Gatu-Johnson M. , Gorini G. , Hellesen C. , Kiptily V. , Mlynar J. , Perez von Thun C. , Pillon M. , Popovichev S. , Syme B. , Tardocchi M. , Zoita V. L. ,   EFDA-JET Contributors
Published: October 2010

Notwithstanding the advances of the past decades, significant developments are still needed to satisfactorily diagnose “burning plasmas.” D–T plasmas indeed require a series of additional measurements for the optimization and control of the configuration: the 14 MeV neutrons, the isotopic composition of the main plasma, the helium ash, and the redistribution and losses of the alpha particles. Moreover a burning plasma environment is in general much more hostile for diagnostics than purely deuterium plasmas. Therefore, in addition to the development and refinement of new measuring techniques, technological advances are also indispensable for the proper characterization of the next generation of devices. On JET an integrated program of diagnostic developments, for JET future and in preparation for ITER, has been pursued and many new results are now available. In the field of neutron detection, the neutron spectra are now routinely measured in the energy range of 1–18 MeV by a time of flight spectrometer and they have allowed studying the effects of rf heating on the fast ions. A new analysis method for the interpretation of the neutron cameras measurements has been refined and applied to the data of the last trace tritium campaign (TTE). With regard to technological upgrades, chemical vapor deposition diamond detectors have been qualified both as neutron counters and as neutron spectrometers, with a potential energy resolution of about one percent. The in situ calibration of the neutron diagnostics, in preparation for the operation with the ITER-like wall, is also promoting important technological developments. With regard to the fast particles, for the first time the temperature of the fast particle tails has been obtained with a new high purity Germanium detector measuring the gamma emission spectrum from the plasma. The effects of toroidal Alfven eigenmodes modes and various MHD instabilities on the confinement of the fast particles have been determined with a combination of gamma ray cameras, neutral particle analyzers, scintillator probe, and Faraday cups. From a more technological perspective, various neutron filters have been tested to allow measurement of the gamma ray emission also at high level of neutron yield.
The anomalous currents in the front foils of the JET lost alpha diagnostic KA-2
Authors: Cecil F. E. , Kiptily V. , Salmi A. , Horton A. , Fullard K. , Murari A. , Darrow D. , Hill K. ,   JET-EFDA Contributors
Published: October 2010

We have examined the observed currents in the front foils of the JET Faraday cup lost alpha particle diagnostic KA-2. In particular, we have sought to understand the currents during Ohmic plasmas for which the ion flux at the detectors was initially assumed to be negligible. We have considered two sources of this current: plasma ions (both deuterium and impurity) in the vicinity of the detector (including charge exchange neutrals) and photoemission from scattered UV radiation. Based upon modeling and empirical observation, the latter source appears most likely and, moreover, seems to be applicable to the currents in the front foil during ELMy H-mode plasmas. A very thin gold or nickel foil attached to the present detector aperture is proposed as a solution to this problem, and realistic calculations of expected fluxes of lost energetic neutral beam ions during TF ripple experiments are presented as justification of this proposed solution.
Neutron spectrometry of JET discharges with ICRH-acceleration of helium beam ions
Authors: Gatu Johnson M. , Sundén E. Andersson , Cecconello M. , Conroy S. , Ericsson G. , Eriksson J. , Gorini G. , Hellesen C. , Kiptily V. , Nocente M. , Sangaroon S. , Sharapov S. E. , Tardocchi M. , van Eester D. , Weiszflog M. ,   JET EFDA Contributors
Published: October 2010

Recent experiments at JET aimed at producing H4e ions in the MeV range through third harmonic ion cyclotron resonance heating (ICRH) acceleration of H4e beams in a H4e dominated plasma. MeV range D was also present through parasitic ICRH absorption on residual D. In this contribution, we analyze TOFOR neutron spectrometer data from these experiments. A consistent description of the data is obtained with d(d,n)H3e and B9e(α,n)C12 neutron components calculated using Stix distributions for the fast D and H4e, taking finite Larmor radius effects into account and with a ICRH power partition of PDRF=0.01×P4HeRF, in agreement with TOMCAT simulations.
Analysis and improvements of fringe jump corrections by electronics on the JET tokamak far infrared interferometer
Authors: Gil C. , Barbuti A. , Spuig P. , Boboc A. , Dorling S. ,   JET EFDA Contributors
Published: October 2010

For the Tore Supra interferometer phase measurements, an electronics had been developed electronics using field programmable gate array processors. The embedded algorithm can correct the fringe jumps. For comparison, the electronics ran at JET during the 2009 campaign. The first analysis concluded that the electronics was not correcting all the fringe jumps. An analysis of the failures led to improvements in the algorithm, which was tested during the rest of the campaign. In this article, we evaluate the increases in the performance. From the analysis of the remaining faults, further improvements are discussed for designing future boards that are foreseen for JET using the second wavelength and the Cotton–Mouton effect information.
Charged fusion product loss measurements using nuclear activation
Authors: Bonheure G. , Hult M. , González de Orduña R. , Arnold D. , Dombrowski H. , Laubenstein M. , Wieslander E. , Vermaercke P. , Murari A. , Popovichev S. , Mlynar J. ,   JET-EFDA Contributors
Published: October 2010

In ITER, α particle loss measurements will be required in order to understand the alpha particle physics. Techniques capable of operating in a fusion reactor environment need further development. Recent experimental studies on JET demonstrated the potential of nuclear activation to measure the flux of escaping MeV ions. New results from MeV ion induced activation of metallic, ceramic, and crystal samples placed near the plasma edge are reported. Activation products were measured as function of orientation with respect to the magnetic field as well as function of the distance to the plasma. Sample activity was measured using ultralow-level gamma-ray spectrometry. Distribution of 14.68 MeV fusion proton induced activation products is strongly anisotropic in agreement with simulations and falls off sharply with increasing distance to the plasma. Prospects for using the technique in ITER are discussed.
Measure of electron cyclotron emission at multiple angles in high Te plasmas of JET
Authors: Figini L. , Garavaglia S. , De La Luna E. , Farina D. , Platania P. , Simonetto A. , Sozzi C. ,   JET-EFDA Contributors
Published: October 2010

The oblique electron cyclotron emission (ECE) diagnostic installed at JET allows simultaneous analysis of the ECE spectra along three lines of sight (with toroidal angles of 0°, ∼10°, and ∼20°) and two linear polarizations for each oblique line of sight. The diagnostic is capable of measuring EC emission over the band of 75–800 GHz with 5 ms time resolution and 7.5 GHz spectral resolution, and it is designed to investigate the features of ECE spectra related to electron distribution in the thermal velocity range. Instrumental accuracy was assessed using sources at different temperatures (77–900 K) and with plasma emission. ECE from high temperature plasmas and in the presence of fast ions has been compared to simulations performed with the modeling code SPECE, setting an upper limit to possible discrepancies from thermal emission.
Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array
Authors: Darrow D. S. , Cecil F. E. , Kiptily V. , Fullard K. , Horton A. , Murari A. ,   JET EFDA Contributors
Published: October 2010

The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ∼2 MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential.
Neutron spectroscopy results of JET high-performance plasmas and extrapolations to DT performance
Authors: Hellesen C. , Andersson Sundén E. , Conroy S. , Ericsson G. , Eriksson J. , Gatu Johnson M. , Weiszflog M. ,   JET-EFDA Contributors
Published: October 2010

In a fusion reactor with high energy gain, the fusion power will be mainly thermonuclear (THN). Measurements of the THN neutron rate are a good performance indicator of a fusion plasma, requiring neutron emission spectroscopy (NES) measurements to distinguish thermal and nonthermal contributions. We report here on recent NES results from JET high-performance plasmas with high fractions (about 65%) of THN emission. The analysis is made with a framework for analyzing NES data, taking into account THN reactions and beam-target reactions. The results are used to extrapolate to the equivalent DT rates. Finally, we discuss the applicability of using NES in the deuterium phase of ITER, both for the extrapolations to ITER’s future DT performance as well as for the measurements of confined energetic ions.
Detection of dust on JET with the high resolution Thomson scattering system
Authors: Giovannozzi E. , Beurskens M. , Kempenaars M. , Pasqualotto R. , Rydzy A. , Contributors JET EFDA
Published: October 2010

Dust particles have been observed with Thomson scattering systems on several tokamaks. We present here the first evidence of dust particles observed by the new high resolution Thomson scattering system on JET. The system consists of filter spectrometers that analyze the Thomson scattering spectrum from 670 to 1050 nm in four spectral channels. The laser source is a 5 J Q-switched Nd:YAG laser. Without a spectral channel at the laser wavelength, only dust particles that emit broadband light could be detected; these particles have been observed on JET after disruptions. The timing of their emission is clearly different from that expected for a Thomson scattering pulse. The light pulse from dust happens after the peak of the laser light and has a long tail.
Generalized dispersion relation for electron Bernstein waves in a non-Maxwellian magnetized anisotropic plasma
Authors: Deeba F. , Ahmad Zahoor , Murtaza G.
Published: October 2010

A generalized dielectric constant for the electron Bernstein waves using non-Maxwellian distribution functions is derived in a collisionless, uniform magnetized plasma. Using the Neumann series expansion for the products of Bessel functions, we can derive the dispersion relations for both kappa and the generalized (r,q) distributions in a straightforward manner. The dispersion relations now become dependent upon the spectral indices κ and (r,q) for the kappa and the generalized (r,q) distribution, respectively. Our results show how the non-Maxwellian dispersion curves deviate from the Maxwellian depending upon the values of the spectral indices chosen. It may be noted that the (r,q) dispersion relation is reduced to the kappa distribution for r=0 and q=κ+1, which, in turn, is further reducible to the Maxwellian distribution for κ→∞.
Direct growth of few-layer graphene on 6H-SiC and 3C-SiC/Si via propane chemical vapor deposition
Authors: Michon A. , Vézian S. , Ouerghi A. , Zielinski M. , Chassagne T. , Portail M.
Published: October 2010

We propose to grow graphene on SiC by a direct carbon feeding through propane flow in a chemical vapor deposition reactor. X-ray photoemission and low energy electron diffraction show that propane allows to grow few-layer graphene (FLG) on 6H-SiC(0001). Surprisingly, FLG grown on (0001) face presents a rotational disorder similar to that observed for FLG obtained by annealing on (000–1) face. Thanks to a reduced growth temperature with respect to the classical SiC annealing method, we have also grown FLG/3C-SiC/Si(111) in a single growth sequence. This opens the way for large-scale production of graphene-based devices on silicon substrate.
Thickness dependence on crystalline structure and interfacial reactions in HfO2 films on InP (001) grown by atomic layer deposition
Authors: Kang Y. S. , Kim C. Y. , Cho M. -H. , Chung K. B. , An C. -H. , Kim H. , Lee H. J. , Kim C. S. , Lee T. G.
Published: October 2010

The crystalline structure and interfacial reactions in HfO2 films grown on InP (001) substrates was investigated as a function of film thickness. High resolution transmission electron microscopy and x-ray diffraction measurements were used to investigate changes in the crystalline structure of the HfO2 films. As the thickness of the HfO2 increased, the crystal structure was transformed from monoclinic to tetragonal, and the interfacial layer between the HfO2 film and the InP substrate disappeared. High resolution x-ray photoelectron spectroscopy was also applied to confirm the existence of an interfacial chemical reaction in HfO2/InP. An interfacial self-cleaning effect occurred during the atomic layer deposition process, resulting in a clear interface with no indication of an interfacial layer between the HfO2 film and the InP surface. Finally, the crystallization process in the HfO2 films was found to be significantly affected by the interfacial energy.
Angular dependent magnetoresistance with twofold and fourfold symmetries in A-type antiferromagnetic Nd0.45Sr0.55MnO3 thin film
Authors: Zhang Y. Q. , Meng H. , Wang X. W. , Wang X. , Guo H. H. , Zhu Y. L. , Yang T. , Zhang Z. D.
Published: October 2010

The angular dependent magnetoresistance (AMR) of Nd0.45Sr0.55MnO3 thin film epitaxially grown on SrTiO3 (001) is examined at different temperatures and magnetic fields. Twofold and fourfold symmetric AMR and a transition between them are observed under two different measurement modes and are found to be dependent on temperature and/or strength of a magnetic field. In comparison with AMR occurring in other systems, we believe that the twofold/fourfold symmetric AMR observed here corresponds to different spin-canted states induced by the magnetic field at certain temperatures below the Néel temperature.
On Richtmyer–Meshkov instability in dilute gas-particle mixtures
Authors: Ukai Satoshi , Balakrishnan Kaushik , Menon Suresh
Published: October 2010

Richtmyer–Meshkov instability (RMI) in gas-particle mixtures is investigated both numerically and analytically. The linear amplitude growth rate for a RMI in a two-phase mixture is derived by using a dusty gas formulation for small Stokes number (St⪡1.0), and it is shown that the problem can be characterized by mass loading and St. The model predictions are compared with numerical results under two conditions, i.e., a shock wave hitting (1) a perturbed species interface of air and SF6 surrounded by uniformly distributed particles, and (2) a perturbed shape particle cloud in uniform air. In the first case, the interaction between the instability of the species perturbation and the particles is investigated. The multiphase growth model accurately predicts the growth rates when St⪡1.0, and the amplitude growth normalized by the two-phase RMI velocity shows good agreement with the single-phase RMI growth rate as well. It is also shown that the two-phase model results are in accordance with the growth rates obtained from the simulations even for cases corresponding to St≈10. However, for St⪢10, particles do not follow the RMI motion, and the RMI growth rate agrees with the original Richtmyer’s model [R. D. Richtmyer, “Taylor instability in shock acceleration of compressible fluids,” Commun. Pure Appl. Math. 13, 297 (1960)]. Preferential concentration of particles are observed around the RMI roll-ups at late times when St is of order unity, whereas when St⪡1.0, the particles respond rapidly to the flow, causing them to distribute within the roll-ups. In the second problem, the two-phase RMI growth model is extended to study whether a perturbed dusty gas front shows RMI-like growth due to the impact of a shock wave. When St⪡1.0, good agreement with the multiphase model is again seen. Moreover, the normalized growth rates are very close to the single-phase RMI growth rates even at late times, which suggest that the two-phase growth model is applicable to this type of perturbed shape particle clouds as well. However, when St is close to unity or larger (St>1.0), the particles do not experience impulsive acceleration but rather a continuous one, which results in exponential growth rates as seen in a Rayleigh–Taylor instability.
Subwavelength imaging by a simple planar acoustic superlens
Authors: Jia Han , Ke Manzhu , Hao Rui , Ye Yangtao , Liu Fengming , Liu Zhengyou
Published: October 2010

We experimentally realized a planar acoustic superlens by a simple structure consisting of periodically arrayed rigid slabs. Based on the excitation of guided modes and the moderate amplification of the evanescent waves, we have broken the diffraction limit and obtained a subwavelength image with a half-power beamwidth of 0.07λ. All the experimental results are in good agreement with the theoretical simulations via finite difference time domain method.
A novel tunable filter featuring defect mode of the TE wave from one-dimensional photonic crystals doped by magnetized plasma
Authors: Kong Xiang-kun , Liu Shao-bin , Zhang Hai-feng , Li Chun-zao
Published: October 2010

A novel tunable filter featuring the defect mode of the TE wave from one-dimensional photonic crystals doped by magnetized plasma is presented. The photonic crystals are composed by SiO2 and air with one defect layer made by magnetized plasma. By the transfer matrix method and Bloch’s theorem, we find out that the frequency of the defect mode can be modulated by plasma density or external magnetic field. Without changing the structure of the photonic crystal, the defect mode can be modulated in a larger frequency range, especially when the left-hand polarized electromagnetic wave is utilized.
The interplay of intermediate reflectors and randomly textured surfaces in tandem solar cells
Authors: Fahr Stephan , Rockstuhl Carsten , Lederer Falk
Published: October 2010

By using rigorous diffraction theory we investigate the potential for enhancing the efficiency of tandem solar cells by means of various intermediate reflectors and randomly textured surfaces simultaneously. We show that the superior efficiency of tandem solar cells with intermediate reflectors can be further enhanced by incorporating randomly textured surfaces. Since such surfaces are always present in realistic devices, these findings will have a tremendous impact in paving the way toward the integration of state-of-the-art intermediate reflectors into actual solar cells.
Energy transfer from phosphorescent blue-emitting oxidized porous silicon to rhodamine 110
Authors: Gelloz Bernard , Harima Noboru , Koyama Hideki , Elhouichet Habib , Koshida Nobuyoshi
Published: October 2010

Nanocomposites consisting of oxidized porous Si (OPSi) impregnated with rhodamine 110 (Rh110) molecules are characterized in terms of luminescence properties. The photoluminescence and its polarization memory strongly indicates a trace of energy transfer from the fast blue luminescence band of OPSi to the green one of Rh110. Time-resolved experiments showed that energy transfer to Rh110 also takes place from the long-lived blue phosphorescence of OPSi. The transfer channel from nonradiative states of OPSi to Rh110 was also found. The ability of OPSi to harvest and transfer absorbed photon energy to a guest is promising for applications in optoelectronics and biology.
The Personality of Environmental Prediction: Griffith Taylor as 'Latter-day Prophet'
Authors: Strange Carolyn
Published: October 2010

Environmental prediction is a practice that may establish and enhance the status of predictors but it also carries risks that vary in relation to the professional and political contexts of its communication. Exploring the lives of scientists involved in the difficult task of environmental prediction highlights the significance of personal identities in the cultural history of science. Geographer Griffith Taylor (1880?1963), whose raison d'�tre was environmental prediction, is an ideal subject to examine from this perspective. Facing opposition to his early predictions of Australia's limited settlement prospects, owing to the continent's aridity, he used intemperate language to deliver sober warnings and sparred with naysayers and doubters in the popular media. By the 1920s he saw himself as a ?latter-day prophet', and he carried that sense of self forward when he moved to North America in 1928. Yet in Canada his environmental predictions, although favourable, were considered overly optimistic and often disregarded altogether. This prophet realized that he was happier being attacked than ignored. Taylor's career suggests that positive prognostication, when dismissed, offers less personal compensation than cautionary prophesies that face opposition in hostile political or intellectual contexts.
Gregory Maxwell Kelly 1930 - 2007
Authors: Street Ross
Published: October 2010

Gregory Maxwell (?Max') Kelly (1930?2007) was educated at the University of Sydney (BSc 1951 with First Class Honours, University Medal for Mathematics, Barker Prize, and James King of Irrawang Travelling Scholarship) and the University of Cambridge (BA 1953 with First Class Honours and two Wright's Prizes; Rayleigh Prize, 1955; PhD 1957). He returned to Australia as Lecturer in Pure Mathematics at the University of Sydney in 1957, became Senior Lecturer in 1961 and Reader in 1965. He was appointed Professor of Pure Mathematics first at the University of New South Wales in 1967 then at the University of Sydney in 1973, becoming Professor Emeritus in 1994. He introduced the mathematical discipline of category theory to Australia and continued active and influential research in the subject until the day of his death.
Francis Lions: The Early Development of His Interest in Coordination Chemistry
Authors: Hawkins Jenny , Goodwin Harold A.
Published: October 2010

A letter written by Francis Lions to Linus Pauling in 1939 sheds light on the early development of Lions' work in the field of coordination chemistry. Together with the subject matter of some of his relatively early publications, it reveals how he was developing the synthetic strategies that later were applied to the successful design and function of sexadentate chelating agents.
Ronald Drayton Brown 1927 - 2008
Authors: Godfrey Peter D. , Larkins Francis P. , Swan John M.
Published: October 2010

Ronald Drayton Brown AM, FAA (1927?2008) was born in Melbourne and had a distinguished scientific career spanning more than sixty years. He was an outstanding, internationally respected researcher in the fields of theoretical chemistry, microwave spectroscopy and galactochemistry, publishing more than 300 scientific papers, three books and three patents. He had the unique distinction of being the first professor appointed to the newly established Monash University in 1959. As Foundation Professor of Chemistry and Head of Department he had the vision, leadership skills and commitment to establish a Department that was to become one of the finest in Australia. He was a mentor to many staff and students. His legacy will shape the direction of Monash chemistry for many years.
Gene therapy-mediated delivery of targeted cytotoxins for glioma therapeutics
Authors: Candolfi Marianela , Xiong Weidong , Yagiz Kader , Liu Chunyan , Muhammad A. K. M. G. , Puntel Mariana , Foulad David , Zadmehr Ali , Ahlzadeh Gabrielle E. , Kroeger Kurt M. , Tesarfreund Matthew , Lee Sharon , Debinski Waldemar , Sareen Dhruv , Svendsen Clive N. , Rodriguez Ron , Lowenstein Pedro R. , Castro Maria G.
Published: October 2010

Restricting the cytotoxicity of anticancer agents by targeting receptors exclusively expressed on tumor cells is critical when treating infiltrative brain tumors such as glioblastoma multiforme (GBM). GBMs express an IL-13 receptor (IL13Rα2) that differs from the physiological IL4R/IL13R receptor. We developed a regulatable adenoviral vector (Ad.mhIL-4.TRE.mhIL-13-PE) encoding a mutated human IL-13 fused to
Pseudomonas
exotoxin (mhIL-13-PE) that specifically binds to IL13Rα2 to provide sustained expression, effective anti-GBM cytotoxicity, and minimal neurotoxicity. The therapeutic Ad also encodes mutated human IL-4 that binds to the physiological IL4R/IL13R without interacting with IL13Rα2, thus inhibiting potential binding of mhIL-13-PE to normal brain cells. Using intracranial GBM xenografts and syngeneic mouse models, we tested the Ad.mhIL-4.TRE.mhIL-13-PE and two protein formulations, hIL-13-PE used in clinical trials (Cintredekin Besudotox) and a second-generation mhIL-13-PE. Cintredekin Besudotox doubled median survival without eliciting long-term survival and caused severe neurotoxicity; mhIL-13-PE led to ∼40% long-term survival, eliciting severe neurological toxicity at the high dose tested. In contrast, Ad-mediated delivery of mhIL-13-PE led to tumor regression and long-term survival in over 70% of the animals, without causing apparent neurotoxicity. Although Cintredekin Besudotox was originally developed to target GBM, when tested in a phase III trial it failed to achieve clinical endpoints and revealed neurotoxicity. Limitations of Cintredekin Besudotox include its short half-life, which demanded frequent or continued administration, and binding to IL4R/IL13R, present in normal brain cells. These shortcomings were overcome by our therapeutic Ad, thus representing a significant advance in the development of targeted therapeutics for GBM.
Distribution and importance.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter discusses the origin, early and present distribution of bananas and plantains (Musa). The main banana-producing countries are presented, which are classified (according to world production and trade) into four large groups, namely the dollar area, ACP countries (referring to the 48 African, Caribbean and Pacific countries), EU producers and other producing countries. The main banana markets, i.e. the markets for tropical export bananas, for subtropical local production, for local trade and staple diets, and for processing, are described. Some factors influencing world trade, including political, environmental, social and quarantine issues, as well as climatic disasters, are discussed.
Taxonomic classification, cultivars and breeding.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter describes the basis of modern classification and the major genomic groups and cultivars of bananas and plantains (Musa). Two selection criteria for genetic improvement, i.e. resistance to pests and diseases and agronomic, postharvest and quality characteristics, are discussed, as well the five breeding methods used for banana and plantain improvement, namely: (i) field selection; (ii) conventional breeding; (iii) somaclonal variation (the production of natural mutants during in vitro multiplication of banana meristems); (iv) induced mutation breeding; and (v) genetic engineering. The storage, transport and identification (using biochemical and molecular markers) of banana germplasm are also discussed.
Site selection, soil requirements and soil preparation.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This paper provides information on the different points to consider in selecting sites for banana production. Topics covered include: tropical soil classification; soil physical requirements (porosity and compaction, aeration and drainage, water-holding capacity, soil temperature and soil texture); soil chemical requirements (cation balance, soil acidity and soil salinity); soil biological limitations; and soil preparation.
Establishing a plantation.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter describes the two types of banana (Musa) planting material, i.e. the conventional and in vitro (tissue culture), as well as their multiplication and preparation. The advantages and disadvantages of using in vitro-propagated planting materials in banana production technology are enumerated. The methods and time of planting of banana plants in tropical and subtropical localities are also described. The determinants of plant density choice are discussed: (i) prevailing climate; (ii) level of plantation vigour; and (iii) expected plantation longevity, as well as the general disadvantages of high or low plant densities. The importance of their spatial arrangement is also emphasized. A tabulated summary is provided of commercial practices worlwide, relating to plant crop densities, initial spatial arrangements, number of followers selected and ratoon densities, for banana and plantain.
Nutritional requirements.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter deals with the nutrient requirements of banana and plantain plants (Musa). The different functions and deficiency symptoms of these nutrients are described, which include the macronutrients N, P, K, Ca, Mg and S and the microelements Zn, Mn, B, Fe and Cu. The interactions (antagonism and synergism) between these nutrients are briefly described. Phytotoxicity due to excess Cl and Al are mentioned. The importance of plant analysis and nutrient cycling in planning fertilizer strategy is discussed, and the different application methods and types of fertilizer are summarized. The use of organic amendments (such as cow or chicken manure and composts from crop residues) due to progressive physical, chemical and biological degradation of soils following intensive use of fertilizers and pesticides is also discussed.
Horticultural management.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter deals with some horticultural management practices in banana (Musa) plantations. These include weed control (using herbicides, hand hoeing, organic mulching and intercropping), sucker management (by desuckering and ratoon sucker selection), mulching, cover cropping, intercropping, canopy management, planting of living windbreaks, and bunch propping, trimming and covering using polyethylene. The lifespan of banana plantations and their productivity are described, as well as the importance of crop rotation in banana production.
Diseases.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter covers the main fungal, bacterial and viral diseases of banana (Musa) and their symptoms, transmission and control (using chemical, biological, cultural methods and disease-resistant cultivars). These fungal diseases include black Sigatoka caused by the airborne fungus Mycosphaerella fijiensis, Panama disease or Fusarium wilt caused by many different strains or genotypes of the soil-borne pathogen Fusarium oxysporum, and anthracnose peel blemish caused by Colletotrichum musae. Some of the bacterial diseases include the Moko disease caused by Ralstonia solanacearum and Xanthomonas wilt. The viral pathogens include the Banana bunchy top virus, Cucumber mosaic virus, Banana bract mosaic virus and Banana streak virus. The role of fungal and bacterial endophytes in controlling banana diseases is mentioned.
Pests.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter describes the morphology, life cycle, spread and control (by chemical, biological, cultural and quarantine methods) of pests attacking bananas and plantains (Musa). These include the rhizome and root pests (the banana weevil Cosmopolites sordidus and burrowing nematode Radopholus similis), the bunch pests (including thrips and scab moth Nacoleia octasema), and the leaf pests (such as the leaf-eating caterpillar Antichloris viridis and the mealybug Dysmicoccus grasii). The role of fungal and bacterial endophytes in controlling banana pests and diseases is discussed.
Harvesting and fruit handling.
Authors: Robinson J. C. , Galán Saúco V.
Published: October 2010

This chapter deals with fruit maturity standards and harvesting procedures for bananas and plantains (Musa). The transport systems from the field to the market are discussed. The cooling of fruits from the field are described, providing several guidelines that can be recommended to banana producers to help control the overheating problem in very hot conditions. The successive packshed operations involved for commercial bananas are described, i.e. dehanding, washing and delatexing, clustering, fungicide treatment, quality control operations and packing. A summary of the EU Directive 2257/94 (EUR.lex, 2010b), regarding fruit quality, presentation and marking, for Cavendish bananas imported to EU markets, is presented.
PPO: Predictor for Prokaryotic Operons
Authors: Chuang Li-Yeh , Tsai Jui-Hung , Yang Cheng-Hong
Published: October 2010

Summary: We present an operon predictor for prokaryotic operons (PPO), which can predict operons in the entire prokaryotic genome. The prediction algorithm used in PPO allows the user to select binary particle swarm optimization (BPSO), a genetic algorithm (GA) or some other methods introduced in the literature to predict operons. The operon predictor on our web server and the provided database are easy to access and use. The main features offered are: (i) selection of the prediction algorithm; (ii) adjustable parameter settings of the prediction algorithm; (iii) graphic visualization of results; (iv) integrated database queries; (v) listing of experimentally verified operons; and (vi) related tools.

Availability and implementation: PPO is freely available at http://bio.kuas.edu.tw/PPO/.

Contact:  chyang@cc.kuas.edu.tw

Supplementary information:  Supplementary data are available at Bioinformatics online.
Identification of predominant culturable vaginal Lactobacillus species and associated bacteriophages from women with and without vaginal discharge syndrome in South Africa
Authors: Damelin Leonard H. , Paximadis Maria , Mavri-Damelin Demetra , Birkhead Monica , Lewis David A. , Tiemessen Caroline T.
Published: October 2010

Lactobacillus jensenii, Lactobacillus crispatus, Lactobacillus iners, Lactobacillus gasseri and Lactobacillus vaginalis were identified by 16S rRNA gene sequencing as the predominant culturable vaginal Lactobacillus species in a group of South African women, comprising 24, 22, 10, 10 and 9 %, respectively. A significant effect of vaginal discharge syndrome (VDS) and bacterial vaginosis (BV) on the distribution of predominant Lactobacillus species was observed. Whilst L. crispatus isolates were almost equally distributed between individuals with and without VDS and were not significantly reduced in women with BV versus normal microflora, L. jensenii isolates were significantly reduced in women with VDS (P=0.022) and reduced in women with BV versus normal microflora (P=0.053). Unlike L. crispatus, L. jensenii isolates were also significantly reduced in women with BV-associated VDS versus women without VDS and with normal microflora (P=0.051). In addition, lysogeny was commonly observed for L. crispatus, with 77 % of isolates yielding phage particles with contractile and non-contractile tails. Only 29 % of L. jensenii isolates yielded phage particles, and these were visible as tailless or podo-like particles.
Role of the phenazine-inducing protein Pip in stress resistance of Pseudomonas chlororaphis
Authors: Girard Geneviève , Rigali Sébastien
Published: October 2010

The triggering of antibiotic production by various environmental stress molecules can be interpreted as bacteria's response to obtain increased fitness to putative danger, whereas the opposite situation – inhibition of antibiotic production – is more complicated to understand. Phenazines enable Pseudomonas species to eliminate competitors for rhizosphere colonization and are typical virulence factors used for model studies. In the present work, we have investigated the negative effect of subinhibitory concentrations of NaCl, fusaric acid and two antibiotics on quorum-sensing-controlled phenazine production by Pseudomonas chlororaphis. The selected stress factors inhibit phenazine synthesis despite sufficient cell density. Subsequently, we have identified connections between known genes of the phenazine-inducing cascade, including PsrA (Pseudomonas sigma regulator), RpoS (alternative sigma factor), Pip (phenazine inducing protein) and PhzI/PhzR (quorum-sensing system). Under all tested conditions, overexpression of Pip or PhzR restored phenazine production while overexpression of PsrA or RpoS did not. This forced restoration of phenazine production in strains overexpressing regulatory genes pip and phzR significantly impairs growth and stress resistance; this is particularly severe with pip overexpression. We suggest a novel physiological explanation for the inhibition of phenazine virulence factors in pseudomonas species responding to toxic compounds. We propose that switching off phenazine-1-carboxamide (PCN) synthesis by attenuating pip expression would favour processes required for survival. In our model, this ‘decision’ point for promoting PCN production or stress resistance is located downstream of rpoS and just above pip. However, a test with the stress factor rifampicin shows no significant inhibition of Pip production, suggesting that stress factors may also target other and so far unknown protagonists of the PCN signalling cascade.
Immunoreactive Coxiella burnetii Nine Mile proteins separated by 2D electrophoresis and identified by tandem mass spectrometry
Authors: Deringer James R. , Chen Chen , Samuel James E. , Brown Wendy C.
Published: October 2010

Coxiella burnetii is a Gram-negative obligate intracellular pathogen and the causative agent of Q fever in humans. Q fever causes acute flu-like symptoms and may develop into a chronic disease leading to endocarditis. Its potential as a bioweapon has led to its classification as a category B select agent. An effective inactivated whole-cell vaccine (WCV) currently exists but causes severe granulomatous/necrotizing reactions in individuals with prior exposure, and is not licensed for use in most countries. Current efforts to reduce or eliminate the deleterious reactions associated with WCVs have focused on identifying potential subunit vaccine candidates. Both humoral and T cell-mediated responses are required for protection in animal models. In this study, nine novel immunogenic C. burnetii proteins were identified in extracted whole-cell lysates using 2D electrophoresis, immunoblotting with immune guinea pig sera, and tandem MS. The immunogenic C. burnetii proteins elicited antigen-specific IgG in guinea pigs vaccinated with whole-cell killed Nine Mile phase I vaccine, suggesting a T cell-dependent response. Eleven additional proteins previously shown to react with immune human sera were also antigenic in guinea pigs, showing the relevance of the guinea pig immunization model for antigen discovery. The antigens described here warrant further investigation to validate their potential use as subunit vaccine candidates.
The cell envelope stress response mediated by the LiaFSR Lm three-component system of Listeria monocytogenes is controlled via the phosphatase activity of the bifunctional histidine kinase LiaS Lm
Authors: Fritsch Frederike , Mauder Norman , Williams Tatjana , Weiser Julia , Oberle Markus , Beier Dagmar
Published: October 2010

Most members of the phylum Firmicutes harbour a two-component system (TCS), LiaSR, which is involved in the response to cell envelope stress elicited most notably by inhibitors of the lipid II cycle. In all LiaSR systems studied in detail, LiaSR-mediated signal transduction has been shown to be negatively controlled by a membrane protein, LiaF, encoded upstream ofliaSR. In this study we have analysed the LiaSR orthologue ofListeria monocytogenes(LiaSRLm). Whole-genome transcriptional profiling indicated that activation of LiaSRLmresults in a remodelling of the cell envelope via the massive upregulation of membrane-associated and extracytoplasmic proteins in the presence of inducing stimuli. As shown for other LiaSR TCSs, LiaSRLmis activated by cell wall-active antibiotics. We demonstrate that the level of phosphorylated LiaRLm, which is required for the induction of the LiaSRLmregulon, is controlled by the interplay between the histidine kinase and phosphatase activities of the bifunctional sensor protein LiaSLm. Our data suggest that the phosphatase activity of LiaSLmis stimulated by LiaFLmin the absence of cell envelope stress.