bluuebunny/crossref_metadata_2025 huggingface dataset:
Conduction mechanisms at low- and high-resistance states in aluminum/anodic aluminum oxide/aluminum thin film structure
Authors: Zhu W. , Chen T. P. , Liu Y. , Fung S.
Published: September 2012

In this work, conduction mechanisms of Al/anodic Al oxide/ Al structure, which exhibits resistive switching behavior, have been investigated. The low-resistance state shows ohmic conduction with a metal-like behavior similar to that of pure aluminum. The situation can be explained by the existence of the metallic filament formed by the excess Al in the Al oxide. On the other hand, the high-resistance state (HRS) shows two distinct regimes: ohmic conduction at low fields with a semiconductor-like behavior; and a non-ohmic conduction at high fields. The ohmic conduction of HRS at low fields is attributed to the electron hopping between the states in the oxide with the activation energy of ∼0.23 eV. It is suggested that the conduction of HRS at high fields (the maximum voltage is lower than the set voltage) is due to the field-enhanced thermal excitation of the electrons trapped in the states of the metallic Al nano-phase into the conduction band of the Al oxide or the electron emission from the potential well of the metallic Al nano-phase to the conduction band.
Influences of reflow time and strain rate on interfacial fracture behaviors of Sn-4Ag/Cu solder joints
Authors: Zhang Q. K. , Zhang Z. F.
Published: September 2012

In this study, the influences of reflow time and strain rate on interfacial fracture behaviors of the Sn-4Ag/Cu solder joints were investigated through in-situ observation. The interfacial microstructures of the solder joints reflowed for different times were first observed by scanning electronic microscope and measuring laser confocal microscope. Then tensile tests of the solder joints were conducted using in-situ tensile stage at different strain rates, and the interfacial fracture processes were in-situ observed. The observation results reveal that the thickness and surface roughness of the interfacial Cu6Sn5 layers increase linearly with increasing square root of the reflow time. Due to the serious strain concentration, fractures of the solder joints occur around the solder/Cu6Sn5 interface. The solder joints reflowed for a short time usually fracture inside the solder close to the joint interface, while the long-time reflowed solder joints are more apt to fracture in the interfacial Cu6Sn5 layer, because the stress applied on the Cu6Sn5 grains increases with increasing reflow time and grain size of Cu6Sn5. The solder joints reflowed for moderate time have the highest fracture resistance. At higher strain rate, the solder can apply a higher stress on Cu6Sn5 layer prior to its fracture, making the latter more apt to fracture.
Diffraction study of bending-induced polysynthetic twins in 10M modulated Ni-Mn-Ga martensite
Authors: Chulist R. , Sozinov A. , Straka L. , Lanska N. , Soroka A. , Lippmann T. , Oertel C.-G. , Skrotzki W.
Published: September 2012

Detailed conventional and synchrotron x-ray and electron backscatter diffraction experiments were performed to investigate bending-induced polysynthetic twins in a Ni−Mn−Ga single crystal with five-layered (10M) martensite crystal structure. It was proved that the twin microstructure produced in such a way is composed of type I twins. The type I twins exhibit a relatively high twinning stress of about 0.8 MPa, which limits the performance of bending-induced twins in magnetic actuation.
Domain controlled magnetic and electric properties of variable sized magnetite nano-hollow spheres
Authors: Sarkar Debasish , Mandal Madhuri , Mandal Kalyan
Published: September 2012

Here, we report the synthesis of variable sized magnetite (Fe3O4) nano-hollow spheres in one step template free solvothermal method and their size dependent magnetic and electrical properties. Size of the hollow spheres is varied from 100 nm to 725 nm by changing the concentration of capping agent. Trace of Verway transition is found for all sets of spheres and the Verway transition temperature (TV) increases with increasing size of the spheres. The domain structure of these spheres changes from pseudo single domain to multi domain state as the size increases from 100 nm to 725 nm as evident from Day plots. This change in domain structure also changes the magnetic and electric properties of these spheres. Temperature dependent of high field magnetization of the hollow spheres can be well explained by Bloch's power law with higher than the bulk value of Bloch constant. The Bloch exponent varies from 1.94 to 1.69 with increasing size of the spheres. Frequency dependence of electrical conductivity (σ) shows Jonscher's power law type behaviour and bigger spheres are found to be more conductive than smaller ones due to their multidomain configuration.
Improving the field emission of carbon nanotubes by lanthanum-hexaboride nano-particles decoration
Authors: Kumari Monika , Gautam S. , Shah P. V. , Pal S. , Ojha U. S. , Kumar A. , Naik A. A. , Rawat J. S. , Chaudhury P. K. , Harsh  , Tandon R. P.
Published: September 2012

Field emission of carbon nanotubes (CNTs) was remarkably improved by lanthanum-hexaboride (LaB6) nano-particles (NPs) decoration. CNTs were grown on the silicon substrate by chemical vapor deposition. Field emission of bare CNTs and LaB6-NPs decorated CNTs was carried out under same conditions. Physical, morphological, elemental, and graphitic nature changes were ascertained by scanning electron microscope, transmission electron microscope, energy dispersive x-ray spectroscopy, and Raman analysis. LaB6-NPs decorated CNTs show significant reduction of turn-on electric-field from 3.0 to 2.1 V/μm. A remarkable improvement of more than six-fold from 2.05 to 13.19 mA/cm2 at a field of 4.6 V/μm was also observed in the current-density.
Nanofracture in graphene under complex mechanical stresses
Authors: Zhang Bin , Mei Lanjv , Xiao Haifeng
Published: September 2012

Nanoscale fracture of graphene under coupled in-plane opening and shear mechanical loading is investigated by extensive molecular dynamics simulations. Under opening-dominant loading, zigzag edge cracks grow self-similarly. Otherwise, complex stresses concentrated around crack-tip can manipulate the direction of crack initiation changing by 30° (or multiples of 30°). Toughness determined by obtained critical stress intensity factors 2.63–3.38 nN Å−3/2 demonstrates that graphene is intrinsically brittle opposite to its exceptional high strength at room temperature. Torn zigzag edges are more energetically and kinetically favorable. Cracking of graphene has dependences on local stresses, edge energy, and dynamic effects, which provides a possible way to regulate graphene edges.
Reverse bias degradation in dye solar cells
Authors: Mastroianni Simone , Lanuti Alessandro , Brown Thomas M. , Argazzi Roberto , Caramori Stefano , Reale Andrea , Di Carlo Aldo
Published: September 2012

A prolonged reverse bias (RB) stress forcing a short-circuit current through a dye solar cell, corresponding to the harshest test a shadowed cell may experience in real conditions, can cause the RB operating voltage VRB to drift with time, initially slowly but accelerating for VRB < (−1.65 ± 0.15)V when gas bubbles, identified as H2 (gas chromatography), are produced inside the cell, leading to breakdown. A close connection between VRB, cell performance, and stability was established. Contributions to RB degradation include triiodide depletion and impurities, in particular water. Acting upon these components and setting up protection strategies is important for delivering long-lasting modules.
Magnetization reversal in multisegmented nanowires: Parallel and serial reversal modes
Authors: Allende S. , Vargas N. M. , Altbir D. , Vega V. , Görlitz D. , Nielsch K.
Published: September 2012

We investigate the effect of the dipolar magnetic interaction between magnetic layers mediated by non-magnetic ones in multisegmented nanowires. Multiple symmetric and non-symmetric segments are considered. We observe that due to the dipolar interaction, the magnetization reversal can follow two possible routes, a serial, or a parallel reversal process. We show that by using asymmetrical multi-segmented wires it is possible to stop the magnetization reversal of the system at any particular point.
Effective thermal conductivity of graphene-based composites
Authors: Chu Ke , Jia Cheng-chang , Li Wen-sheng
Published: September 2012

An analytical model for the effective thermal conductivity in graphene nanoplates (GNPs) based composites is presented. The theoretical formula gives good agreements with the existing experimental data available in the literature. In particular, the present model well shows the nonlinear dependence of effective thermal conductivity enhancement ((Ke − Km)/Km) on the GNP volume fraction (f), and it yields a power law (Ke − Km)/Km ∼ f α (1/2 < α < 2) (1/2 < α < 2). Some interesting findings in thermal conductivity behavior of GNP composites based on the present model are also discussed.
In situ control of As dimer orientation on Ge(100) surfaces
Authors: Brückner Sebastian , Supplie Oliver , Barrigón Enrique , Luczak Johannes , Kleinschmidt Peter , Rey-Stolle Ignacio , Döscher Henning , Hannappel Thomas
Published: September 2012

We investigated the preparation of single domain Ge(100):As surfaces in a metal-organic vapor phase epitaxy reactor. In situ reflection anisotropy spectra (RAS) of vicinal substrates change when arsenic is supplied either by tertiarybutylarsine or by background As4 during annealing. Low energy electron diffraction shows mutually perpendicular orientations of dimers, scanning tunneling microscopy reveals distinct differences in the step structure, and x-ray photoelectron spectroscopy confirms differences in the As coverage of the Ge(100):As samples. Their RAS signals consist of contributions related to As dimer orientation and to step structure, enabling precise in situ control over preparation of single domain Ge(100):As surfaces.
Surface plasmon coupling efficiency from nanoslit apertures to metal-insulator-metal waveguides
Authors: Hu Haifeng , Zeng Xie , Wang Lina , Xu Yun , Song Guofeng , Gan Qiaoqiang
Published: September 2012

Coupling is a critical issue for most plasmonic nanostructures. However, the coupling efficiency for many nanoplasmonic architectures is relatively weak due to the lack of theoretical optimization approaches. Consequently, it is essential to address the understanding of the mechanism and improvement of the coupling efficiency through nanoplasmonic structures. In this letter, we provide a theoretical analysis to quantitatively predict the coupling efficiency from infinite-length and finite-length nanoslits to planar metal-insulator-metal (MIM) waveguide structures, both analytically and numerically. This design principle will be useful for the development of MIM plasmonic networks to bridge the gap between photonics, optoelectronics, and nanoelectronics.
Field-effect active plasmonics for ultracompact electro-optic switching
Authors: Çetin Arif E. , Yanik Ahmet A. , Mertiri Alket , Erramilli Shyamsunder , Müstecaplıoğlu Özgür E. , Altug Hatice
Published: September 2012

Merging of electronics and photonics at subwavelength dimensions could potentially allow development of ultracompact electro-optic modulators and active optical interconnects. Here, we introduce a field-effect active plasmonic modulator where the metallic ring serves as both a photonic resonator and a field electrode. By exploiting the simultaneous electronic and photonic functionalities of our plasmonic device, we show devices offering significantly improved modulation depths (as high as ∼10.85 dB) compared to active dielectric micro-ring resonators. Device concepts introduced in this work are applicable in realization of various integrated components and could play an important role in development of active plasmonic circuits.
Valence band offset at Al2O3/In0.17Al0.83N interface formed by atomic layer deposition
Authors: Akazawa M. , Nakano T.
Published: September 2012

The valence band offset, ΔEV, at an Al2O3/In0.17Al0.83N interface formed by atomic layer deposition was measured by x-ray photoelectron spectroscopy. The conventional method of using the core level separation, ΔECL, between O 1s and In 4d resulted in ΔEV = 1.3 eV, which was apparently consistent with the direct observation of the valence band edge varying the photoelectron exit angle, θ. However, ΔECL and full width at half maximum of core-level spectra were dependent on θ, which indicated significant potential gradients in Al2O3 and InAlN layers. An actual ΔEV of 1.2 eV was obtained considering the potential gradients.
Reconnection events in two-dimensional Hall magnetohydrodynamic turbulence
Authors: Donato S. , Servidio S. , Dmitruk P. , Carbone V. , Shay M. A. , Cassak P. A. , Matthaeus W. H.
Published: September 2012

The statistical study of magnetic reconnection events in two-dimensional turbulence has been performed by comparing numerical simulations of magnetohydrodynamics (MHD) and Hall magnetohydrodynamics (HMHD). The analysis reveals that the Hall term plays an important role in turbulence, in which magnetic islands simultaneously reconnect in a complex way. In particular, an increase of the Hall parameter, the ratio of ion skin depth to system size, broadens the distribution of reconnection rates relative to the MHD case. Moreover, in HMHD the local geometry of the reconnection region changes, manifesting bifurcated current sheets and quadrupolar magnetic field structures in analogy to laminar studies, leading locally to faster reconnection processes in this case of reconnection embedded in turbulence. This study supports the idea that the global rate of energy dissipation is controlled by the large scale turbulence, but suggests that the distribution of the reconnection rates within the turbulent system is sensitive to the microphysics at the reconnection sites.
Fractal dust grains in plasma
Authors: Huang F. , Peng R. D. , Liu Y. H. , Chen Z. Y. , Ye M. F. , Wang L.
Published: September 2012

Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.
Evaluation of the wind resource and power performance of a turbine in Tenerife
Authors: Veigas M. , Iglesias G.
Published: September 2012

Tenerife, the largest of the Canary Islands, aims to enhance the contribution of renewable energies to its electricity demand. The objective of this work is twofold: (i) to assess the wind resources and (ii) to evaluate the energy that a specific wind turbine would produce at different locations across the island. Wind data from four meteorological stations covering a period of 91 years (1920–2011) are used. The annual and monthly distributions of wind velocity and power density are evaluated using the Weibull and Rayleigh distributions, and the prevailing wind directions are analyzed. The monthly energy generated by an ideal turbine is compared to that generated by a real turbine for the four study sites. (An ideal turbine extracts all the energy available in the wind, whereas a real turbine is subjected to Betz’ law.) The high availability and capacity factors obtained are indicative of the large wind resource in Tenerife and in particular at three of the four study sites.
White light emission with red-green-blue lasing action in a disordered system of nanoparticles
Authors: Chen Shujing , Zhao Xiaoye , Wang Yanrong , Shi Jinwei , Liu Dahe
Published: September 2012

White light emission from a disordered system with intensity feedback is investigated. The gain material is an ethanol solution with three laser dyes (Coumarin 440, Coumarin 6, Oxazine), and titanium dioxide (TiO2) nanoparticles to provide feedback. A single pulsed laser beam at 355 nm with 8 ns pulse duration is used to pump the dyes. Coumarin 440 and Coumarin 6 are excited first by the pump beam, and part of the Coumarin 6 peak pumps Oxazine. Bright white light emission is obtained by combining blue, green, and red beams with a threshold effect. The working properties and system emission characteristics are discussed.
Probing radiation damage by alternated current conductivity as a method to characterize electron hopping conduction in DNA molecules
Authors: Gomes Paulo J. , Coelho Margarida , Dionísio Madalena , António Ribeiro Paulo , Raposo Maria
Published: September 2012

Analysis of AC electrical conductivity of deoxyribonucleic acid (DNA) thin films, irradiated with ultraviolet (UV) light, revealed that electrical conduction arises from DNA chain electron hopping between base-pairs and phosphate groups. The hopping distance calculated from correlated barrier hopping model equals the distance between DNA base-pairs, which is consistent with the loss of conductivity with irradiation time arising from a decrease in phosphates groups. In the high frequency regime, at a given frequency, real part of conductivity strongly depends on irradiation time particularly for low dose levels suggesting the use of DNA based films for UV radiation sensors.
Sensitivity maximized near-field scanning optical microscope with dithering sample stage
Authors: Park Kyoung-Duck , Lee Seung Gol , Heo Chaejeong , Lee Young Hee , Jeong Mun Seok
Published: September 2012

We developed a new scheme for a higher sensitivity near-field scanning optical microscope (NSOM) by using a dithering sample stage rather than a dithering probe for the constant gap control between probe and sample. In a conventional NSOM, which use tip dithering feedback mechanism, the Q factor drastically decreases from 7783 to 1000 (13%) or even to 100 (1%) because harmonic oscillating characteristic is deteriorated owing to the large change of stiffness and mass of one prong of tuning fork when a probe is attached to it. In our proposed scheme, on the other hand, we use sample dithering feedback mechanism, where the probe is not attached to the tuning fork and the sample is loaded directly onto the surface of dithering tuning fork. Thus, the Q factor does not decrease significantly, from only 7783 to 7480 (96%), because the loaded sample hardly changes the stiffness and mass of tuning fork. Accordingly, gap control between the immobile fiber probe and the dithering sample is performed precisely by detecting the shear force with high sensitivity. Consequently, the extremely high Q factor enables clear observation of graphene sheets with sub-nanometer vertical resolution, which is not possible with a conventional NSOM setup.
Coexistence of coupled magnetic phases in epitaxial TbMnO3 films revealed by ultrafast optical spectroscopy
Authors: Qi J. , Yan L. , Zhou H. D. , Zhu J.-X. , Trugman S. A. , Taylor A. J. , Jia Q. X. , Prasankumar R. P.
Published: September 2012

Ultrafast optical pump-probe spectroscopy is used to reveal the coexistence of coupled antiferromagnetic/ferroelectric and ferromagnetic orders in multiferroic TbMnO3 films through their time domain signatures. Our observations are explained by a theoretical model describing the coupling between reservoirs with different magnetic properties. These results can guide researchers to creating unique kinds of multiferroic materials that combine coupled ferromagnetic, antiferromagnetic, and ferroelectric properties in one compound.
Magnetron-sputter deposition of high-indium-content n-AlInN thin film on p-Si(001) substrate for photovoltaic applications
Authors: Liu H. F. , Tan C. C. , Dalapati G. K. , Chi D. Z.
Published: September 2012

Al0.278In0.722N thin films have been grown on p-type Si(001) and c-plane sapphire substrates by employing radio-frequency magnetron-sputter deposition at elevated temperatures. High-resolution x-ray diffraction, as well as pole-figure measurements, reveals no phase separation of the thin films. The Al0.278In0.722N film grown on p-Si(001) substrate is a typical fiber-texture with AlInN(0001)//Si(001) while that on the c-sapphire exhibits the onset of epitaxy. Microscopic studies reveal that the growth is dominated by a columnar mechanism and the average columnar grain diameter is about 31.5 and 50.8 nm on p-Si(001) and c-sapphire substrates, respectively. Photoluminescence at room-temperature exhibits a strong emission peak at 1.875 eV, smaller than the optical absorption edge (2.102 eV) but larger than the theoretical bandgap energy (1.70 eV), which is attributable to the band-filling effect, as is supported by the high electron density of 4.5 × 1020 cm−3. The n-Al0.278In0.722N/p-Si(001) heterostructure is tested for solar cells and the results are discussed based on the I-V characteristics and their fittings.
The thickness and stretch dependence of the electrical breakdown strength of an acrylic dielectric elastomer
Authors: Huang Jiangshui , Shian Samuel , Diebold Roger M. , Suo Zhigang , Clarke David R.
Published: September 2012

The performance of dielectric elastomer actuators is limited by electrical breakdown. Attempts to measure this are confounded by the voltage-induced thinning of the elastomer. A test configuration is introduced that avoids this problem: A thin sheet of elastomer is stretched, crossed-wire electrodes are attached, and then embedded in a stiff polymer. The applied electric field at breakdown, EB, is found to depend on both the deformed thickness, h, and the stretch applied, λ. For the acrylic elastomer investigated, the breakdown field scales as EB = 51  h − 0.25  λ 0.63. The test configuration allows multiple individual tests to be made on the same sheet of elastomer.
Cylindrical, periodic surface lattice—Theory, dispersion analysis, and experiment
Authors: Konoplev I. V. , MacLachlan A. J. , Robertson C. W. , Cross A. W. , Phelps A. D. R.
Published: September 2012

A two-dimensional surface lattice of cylindrical topology obtained via perturbing the inner surface of a cylinder is considered. Periodic perturbations of the surface lead to observation of high-impedance, dielectric-like media and resonant coupling of surface and non-propagating volume fields. This allows synthesis of tailored-for-purpose “coating” material with dispersion suitable, for instance, to mediate a Cherenkov type interaction. An analytical model of the lattice is discussed and coupled-wave equations are derived. Variations of the lattice dispersive properties with variation of parameters are shown, illustrating the tailoring of the structure's electromagnetic properties. Experimental results are presented showing agreement with the theoretical model.
Competition between the crystal field and the exchange field in Er3+ doped NdMnO3
Authors: Hong Fang , Cheng Zhenxiang , Wang Xiaolin , Dou Shixue
Published: September 2012

A careful investigation of specific heat shows that the ground state splitting of Nd3+ has been modified by the Er3+ doping, as it shows a nonlinear dependence on the Er3+ doping rate, due to the competition between the crystal field and the exchange field. This competition could be further confirmed by the anomalies in the magnetic entropy and the ground state splitting found in Nd0.9Er0.1MnO3. On the contrary, the ground state splitting of Er3+ has a linear dependence on the doping rate, indicating its stronger dependence on the crystal field rather than the exchange field.
Origin of plasticity in ultrafine lamellar Ti-Fe-(Sn) composites
Authors: Maity T. , Das J.
Published: September 2012

Transmission electron microscopic studies of eutectic Ti68.38Fe28.61Sn3 upon 5% and 10% plastic deformation reveal slip transfer across the β-Ti/FeTi lamellae interface. Stroh's analysis suggests that addition of Sn to Ti70.5Fe29.5 increases the cleavage stress and reduces the slip stress around a dislocation pile-up at β-Ti/FeTi interface. The presence of ultrafine lamellar FeTi contributes strengthening whereas, dislocation slip is the origin of plasticity in high strength Ti-Fe-(Sn) composites.
Introduction.
Authors: Tegos G. , Mylonakis E.
Published: September 2012

This introductory chapter provides a background on the book's purpose and outlines the book's contents and presentation.
Emerging antimicrobial drug-discovery strategies: an evolving necessity.
Authors: Ball A. R. , Tegos G. P.
Published: September 2012

This chapter reviews novel approaches to antimicrobial drug discovery and development, highlighting strategies that can be used to address mechanisms related to antimicrobial drug resistance.
The antibiotic crisis.
Authors: Demain A. L. , Spizek J.
Published: September 2012

This chapter explores important correlates of the current antibiotic crisis, where infectious diseases in general still account for a substantial share of mortality worldwide, antimicrobial drug resistance is prevalent, and current efforts for discovering new antimicrobial compounds are minimal. Reasons for the low turnaround of new antimicrobial drug discovery are discussed, as well as potential solutions to the current antibiotic crisis.
Structure, genetic regulation, physiology and function of the AcrAB-TolC efflux pump of Escherichia coli and Salmonella.
Authors: Amaral L. , Martins A. , Spengler G. , Martins M. , Rodrigues L. , McCusker M. , Ntokou E. , Cerca P. , Machado L. , Viveiros M. , Couto I. , Fanning S. , Kristiansen J. , Molnar J.
Published: September 2012

This chapter reviews current knowledge on the structure and function of the AcrAb-TOlC efflux pump of Escherichia coli and Salmonella. Relevant effects of phenothiazines on the genes that regulate and encode this pump mechanism, as well as on the pump itself, are also described. Future perspectives in relation to this important efflux pump found in drug-resistant bacterial pathogens are discussed.
Small-molecule efflux pump inhibitors from natural products as a potential source of antimicrobial agents.
Authors: Jachak S. M. , Roy S. K. , Shiv Gupta Shiv Gupta , Pallavi Ahirrao Pallavi Ahirrao , Gibbons S.
Published: September 2012

This chapter discusses the potential use of natural products as efflux pump inhibitors (EPIs) in several drug-resistant microbial pathogens, i.e., Mycobacterium, Staphylococcus aureus, Candida albicans. These natural products include various plant flavonoids, curcumin, polyphenols, diterpenes, oligosaccharides and alkaloids. In vitro assays used to screen EPI-related activities of these natural compounds are also outlined.
Fungal efflux-mediated resistance: from targets to inhibitors.
Authors: Monk B. C. , Niimi K. , Holmes A. R. , Strouse J. J. , Sklar L. A. , Cannon R. D.
Published: September 2012

This chapter describes the heterologous expression of fungal efflux pumps in Saccharomyces cerevisiae for medium- and high-throughput screening of pump inhibitors as novel antifungal agents. Strategies for overcoming some limitations of current antifungal drugs and for identifying novel drug targets not subject to efflux-mediated resistance are also discussed.
Drug tolerance, persister cells and drug discovery.
Authors: Lewis K.
Published: September 2012

This chapter discusses the clinical importance of drug tolerance mechanisms and persister cells, and their reletionship to efforts on new antimicrobial drug discovery. Important mechanisms related to biofilm formation in persister cells are also described.
Filamentous temperature-sensitive mutant Z (FtsZ) protein as an antibacterial target.
Authors: Boberek J. M. , Goh Shan Goh Shan , Stach J. , Good L.
Published: September 2012

This chapter reviews current knowledge on the structure, biochemistry and function of the FtsZ protein in bacterial pathogens, highlighting its potential as a promising drug target for the development of novel antibacterial agents. Strategies that can be utilized for the identification of potential Ftsz inhibitors are discussed.
Lysostaphin: a silver bullet for staph.
Authors: Kokai-Kun J. F.
Published: September 2012

This chapter discusses the results of previous studies performed to examine the anti-staphylococcal activity of the novel antibacterial agent lysostaphin, including relevant in vitro models and pre-clinical animal studies.
Strategies to identify modified ribosomally synthesized antimicrobials.
Authors: Marsh A. J. , Hill C. , Ross R. P. , Cotter P. D.
Published: September 2012

This chapter describes various strategies that can be used in identifying novel post-translationally modified, ribosomally synthesized, antimicrobial peptides. Their application in the discovery and evaluation of the lantibiotic family of antimicrobials is discussed.
Quantitative structure - activity relationship-based discovery of antimicrobial peptides active against multidrug-resistant bacteria.
Authors: Fjell C. D. , Jenssen H. , Hancock R. E. W. , Cherkasov A.
Published: September 2012

This chapter discusses concepts related to quantitative structure-activity relationship (QSAR) analyses and their application in the discovery of short cationic antimicrobial peptides for use against multidrug-resistant bacterial pathogens.
Acetyl-CoA carboxylase as a target for antibacterial development.
Authors: Waldrop G. L.
Published: September 2012

This chapter reviews biochemical pathways relevant to bacterial fatty acid synthesis, with emphasis on the important reactions catalysed by the holoenzyme acetyl-CoA carboxylase. Antibacterial compounds previously investigated that inhibit the two component enzymes of the holoenzyme are described, including pyridopyrimidines, amino-oxazoles, benzimidazole carboxamides, and pyrrolidinediones.
Antifungals and antifungal drug discovery.
Authors: Calderone R. , Fonzi W. , Gay-Andrieu F. , Sun N. , Li D. M. , Chen H. , Alex D.
Published: September 2012

This chapter discusses: (1) important clinical aspects of invasive clinical mycoses, i.e., candidosis and aspergillosis; (2) current antifungal therapeutic options for invasive mycoses; (3) antifungal drug resistance; and (4) approaches to antifungal drug discovery, including identification of drug targets.
Pathosystematic studies and the rational design of antifungal interventions.
Authors: Bignell E. M. , Armstrong-James D.
Published: September 2012

This chapter discusses pathosystematic studies in relation to the rational design of new antifungal agents. These pathosystematic studies include whole animal infection models, host and pathogen genome analyses for potential drug targets, functional genomics, transcriptomics and proteomics. Novel antifungal approaches that resulted from these studies, including the use of recombinant interferon- γ, monoclonal antibodies, and natural antifungals, are also described.
Drosophila melanogaster as a versatile model for the discovery of drugs effective against human microbe-induced infection and pathology.
Authors: Apidianakis Y. , Kontoyiannis D. P.
Published: September 2012

This chapter discusses the advantages and limitations of using Drosophila melanogaster as a model for antimicrobial drug discovery, highlighting human infections modelled in the versatile fly, i.e., Pseudomonas aeruginosa, Vibrio cholerae, Serratia marcescens, Enterococcus faecalis, Staphylococcus aureus, Listeria monocytogenes, Cryptococcus neoformans, Aspergillus fumigatus, Candida albicans, and zygomycosis.
Antimicrobial photosensitizers: harnessing the power of light to treat infections.
Authors: Sharma S. K. , Dai T. H. , Hamblin M. R.
Published: September 2012

This chapter focuses on hood therapy as a strategy in treating infectious diseases, e.g., antimicrobial hood therapy (aPDT). Compounds with potential use as antimicrobial photosensitizers are also discussed, including cationic porphyrins, cationic phthalocyanines, cationic bacteriochlorins, phenothiazinium dyes, and cationic fullerenes.
Nanoparticle platforms for antimicrobial therapy.
Authors: Trofa D. , Nosanchuk J. D.
Published: September 2012

This chapter summarizes the potential use of nanoparticles as antimicrobial agents, including descriptions of commonly used vehicles for antimicrobial delivery: liposomes, polymeric nanoparticles, solid lipid nanoparticles, dendrimers, silver nanoparticles. Their future applications in the treatment of tuberculosis, malaria and HIV/AIDS are also explored.
Antimicrobial activity of carbon nanotubes.
Authors: Liu ShaoBin Liu ShaoBin , Chen Yuan Chen Yuan
Published: September 2012

This chapter focuses on the antimicrobial properties of carbon nanotubes (CNTs), highlighting important chemical and molecular structures that may account for their antimicrobial action. Future applications as suggested by the results of current studies are discussed.
Efficacy and Physiological Responses of Grass Carp to Different Sedation Techniques: II. Effect of Pulsed DC Electricity Voltage and Exposure Time on Sedation and Blood Chemistry
Authors: Bowzer John C , Trushenski Jesse T , Gause Brian R , Bowker James D
Published: September 2012

Owing to the current absence of an approved “immediate-release” chemical sedative for use on fish, researchers have been exploring alternative methods that would allow treated fish to be released immediately after sedation, including the use of electrosedation. To address the efficacy of this approach, we evaluated induction and recovery times, survival, and postsedation hematology of grass carp Ctenopharyngodon idella (291 ± 6.7 g, 30.6 ± 0.3 cm TL, mean ± SE) sedated by exposure to 100, 150, or 200 V of pulsed DC (30 Hz and 25% duty cycle) for 5 or 10 s. Regardless of voltage strength or exposure time, all fish were sedated to Stage IV sedation within 0.75 min and recovered within 1.5 min. Although recovery times for fish exposed to electrosedation for 10 s were longer than those for fish electrosedated for 5 s using 100 and 150 V, the opposite trend was observed among fish sedated using 200 V. Overall, induction and recovery times were short: total time elapsed from induction to full recovery ranged from 1.0 to 2.1 min (mean, 1.6 min). No mortalities were observed 24 h postsedation. Hematological changes observed were consistent with an acute stress response, but these effects were transient and few differences were observed among the electrosedation protocols used. Our results indicate that pulsed DC electrosedation is an effective strategy for quickly and easily sedating grass carp.
Efficacy and Physiological Responses of Grass Carp to Different Sedation Techniques: I. Effects of Various Chemicals on Sedation and Blood Chemistry
Authors: Gause Brian R , Trushenski Jesse T , Bowzer John C , Bowker James D
Published: September 2012

Grass carp Ctenopharyngodon idella are commonly used as a low cost, biological control for aquatic vegetation in aquaculture ponds and other private and public waters. In order to minimize the risk of establishing self-sustaining populations in U.S. waters, many states now require grass carp be certified as triploid prior to sale and stocking. To facilitate ploidy testing, grass carp are typically sedated before collecting blood samples. Chemical sedatives such as tricaine methanesulfonate (MS-222) and carbon dioxide (CO2) are most commonly used to sedate fish, but there is increasing interest in other chemical sedatives such as benzocaine and eugenol. We evaluated time to induction to Stage IV sedation and recovery, survival, and postsedation blood chemistry of grass carp (301 ± 8 g, mean ± SE) sedated with MS-222 (150 mg/L), benzocaine (150 mg/L), eugenol (60 mg/L), or CO2 (∼400 mg/L). Induction times for all sedatives excluding CO2 (14.9 min) were less than 2.4 min (range, 1.5–2.4 min). Average recovery time after induction was 5.8 min (range, 2.8–8.3 min) excluding benzocaine, which had a recovery time of 15.4 min. Survival was high and unaffected by sedative option. Plasma cortisol and lactate levels peaked between 0.5 and 1 h postinduction before returning to resting levels at 6 h postinduction. No obvious changes were observed in blood glucose or hematocrit. Each of the sedatives was effective in sedating grass carp, and though changes in blood chemistry indicated that an acute stress response occurred, the response was transient. Although each of the evaluated sedatives would facilitate ploidy testing, some strategies may be more appropriate than others based on FDA approval status and access to the sedative compound, handling time, withdrawal period, and on-site conditions and resources.
Time-resolved measurement of film growth during high-power pulsed magnetron sputtering (HPPMS) of titanium: the rotating shutter concept
Authors: Mitschker F , Prenzel M , Benedikt J , von Keudell A
Published: September 2012

The growth rate during high-power pulsed magnetron sputtering (HPPMS) of titanium is measured with a temporal resolution of up to 54 µs using a rotating shutter concept. According to that concept a 200 µm slit is rotated in front of the substrate synchronous with the HPPMS pulses. Thereby, the growth flux is laterally distributed over the substrate. By measuring the resulting deposition profile with profilometry, the temporal variation of the growth flux per pulse is deduced. The analysis reveals that film growth occurs mainly during a HPPMS pulse, with the growth rate slowly increasing during the pulse and decaying afterwards with a decay time of 100 µs. The maximum of film deposition shifts to earlier times in the pulse with increasing peak power.
Theory of magnetic domains in uniaxial thin films
Authors: Virot F , Favre L , Hayn R , Kuz'min M D
Published: September 2012

For uniaxial thin films, properties of magnetic domains are usually described within the Kittel model, which assumes that domain walls are much thinner than the domains. In this work we present a simple model that includes a proper description of the magnetostatic energy of domains and domain walls and also takes into account the interaction between both surfaces of the film. Our model describes the behaviour of domain and wall widths as a function of film thickness, and is especially well suited for the strong-stripe phase. We prove the existence of a critical value of magneto-crystalline anisotropy above which stripe domains exist for any film thickness and justify our model by comparison with exact results. The model is in good agreement with experimental data for hcp cobalt.
Experimental realization of Cerenkov up-conversions in a 2D nonlinear photonic crystal
Authors: Chen C D , Zhang Y , Zhao G , Hu X P , Xu P , Zhu S N
Published: September 2012

We report on the experimental realization of Cerenkov second harmonic generation and sum-frequency generation in a two-dimensional (2D) LiTaO3 nonlinear photonic crystal. The ferroelectric domain wall enhanced Cerenkov radiations were created by the modulations induced corresponding to the reciprocal vectors along the direction of propagation of the fundamental beams. The (electric field) polarizations of the fundamental beams were found to affect the Cerenkov angles and the intensities of the radiations. In addition, the variations in the characteristics of the radiations varying with the wavelength of the incident fundamental waves were investigated.
Effects of Si addition on the crystallization behaviour of GeTe phase change materials
Authors: Saito Y , Sutou Y , Koike J
Published: September 2012

The effects of the addition of Si on the temperature dependence of the electrical resistance and crystallization temperature, T

x
, of GeTe films were investigated by a two-point probe measurement. T

x
of the (GeTe)100−x
Si
x
films increased with increasing Si content from x = 0 (188 °C) to x = 12.6 at% (297 °C). It was confirmed from XPS measurements that Si–Te bonds were formed in the (GeTe)100−x
Si
x
amorphous film by the addition of Si. The dependence of Si content on the T

x
of the (GeTe)100−x
Si
x
film was calculated based on Lankhorst's model, which showed a linear relationship between T

x
and the Si content. In the region of low Si content (x ⩽ 3.8 at%), the obtained result was in good agreement with the calculated result. Meanwhile, in the region of high Si content (x ⩾ 5.4 at%), the obtained result considerably deviated from the calculated line. This may be due to the formation of the strongest Si–Si bonds in the amorphous (GeTe)100−x
Si
x
film. It was found from XRD measurement that the (GeTe)87.4Si12.6 amorphous film showed crystallization with phase separation into α-GeTe and Si. The obtained results suggested that suitable Si content of the (GeTe)100−x
Si
x
film is in the range 3–7 at% because of the high T

x
, a small temperature interval of crystallization and the absence of phase separation during crystallization.
Fixed-point free endomorphisms and Hopf Galois structures
Authors: Childs Lindsay
Published: September 2012

Let

L

|

K

L|K

be a Galois extension of fields with finite Galois group

G
G

. Greither and Pareigis showed that there is a bijection between Hopf Galois structures on

L

|

K

L|K

and regular subgroups of

P
e
r
m
(
G
)

Perm(G)

normalized by

G
G

, and Byott translated the problem into that of finding equivalence classes of embeddings of

G
G

in the holomorph of groups

N
N

of the same cardinality as

G
G

. In 2007 we showed, using Byott’s translation, that fixed point free endomorphisms of

G
G

yield Hopf Galois structures on

L

|

K

L|K

. Here we show how abelian fixed point free endomorphisms yield Hopf Galois structures directly, using the Greither-Pareigis approach and, in some cases, also via the Byott translation. The Hopf Galois structures that arise are “twistings” of the Hopf Galois structure by

H

λ

H_{\lambda }

, the

K
K

-Hopf algebra that arises from the left regular representation of

G
G

in

P
e
r
m
(
G
)

Perm(G)

. The paper concludes with various old and new examples of abelian fixed point free endomorphisms.
BILATERAL MACULAR SEROUS RETINAL DETACHMENT REVEALING ACUTE MYELOBLASTIC LEUKEMIA
Authors: Caillaux Violaine , Querques Giuseppe , Ramahefasolo Christiane , Darugar Adil , Souied Eric H.
Published: September 2012

Purpose:

To report a case of bilateral serous retinal detachment revealing acute myeloblastic leukemia.

Methods:

A 31-year-old man presenting with decreased vision in both eyes, 20/50 in the right eye and 20/32 in the left eye, was submitted to a complete ophthalmologic and systemic evaluation.

Results:

Fundus biomicroscopy, fluorescein and indocyanine green angiography, and spectral domain optical coherence tomography showed bilateral serous retinal detachment and signs of choroidal ischemia. Enhanced depth imaging spectral domain optical coherence tomography allowed a precise examination of the choroid, by showing an overall thickening of the choroid (749 μm in the right eye and 728 μm in the left eye) and disappearance of the normal hyporeflective visualization of the choroidal vessels. On systemic investigation, the patient was diagnosed with acute myeloblastic leukemia. After systemic chemotherapy, visual acuity improved to 20/20 in both eyes, with resolution of the bilateral serous retinal detachment and choroidal changes.

Conclusion:

Bilateral serous retinal detachment may be a presenting sign of acute myeloblastic leukemia. Examination of the choroid using enhanced depth imaging spectral domain optical coherence tomography may suggest the etiology and contribute to early diagnosis and treatment.
THE USE OF INTRAVITREAL RANIBIZUMAB TO TREAT NEOVASCULAR GLAUCOMA BECAUSE OF RETINAL AMYLOID ANGIOPATHY IN FAMILIAL AMYLOIDOSIS TRANSTHYRETIN V30M RELATED
Authors: Beirão Nuno M. , Miranda Vasco , Beirão Idalina , Costa Paulo P. , Torres Paulo
Published: September 2012

Purpose:

The purpose of this study to report a patient with amyloidotic angiopathy and neovascular glaucoma who was treated with intravitreal injection of ranibizumab followed by laser photocoagulation.

Methods:

A 52-year-old liver-transplanted woman with familial amyloidotic polyneuropathy presented with unilateral rubeosis iridis and neovascular glaucoma. A complete ocular examination and fluorescein and indocyanine green angiography were performed.

Results:

Best-corrected visual acuity before injection was 0.05 (Snellen) in the left eye, and intraocular pressure was 42 mmHg. Fluorescein angiography showed vascular occlusion in the retinal periphery, focal staining of vessels, and microaneurysms. Indocyanine green angiography showed hyperfluorescent spots alongside the choroidal veins. Two days after receiving intravitreal injection of ranibizumab, the clinical picture regressed. The diagnosis of retinal amyloid angiopathy was made, and a peripheral retinal laser photocoagulation was done. The final best-corrected visual acuity after 2 years of follow-up was 0.4 (Snellen) in the left eye.

Conclusion:

Intravitreal injections of ranibizumab should be evaluated for a potential role on the treatment of amyloid angiopathy neovascular glaucoma. Careful retinal periphery examination should be included in the ophthalmologic examination of all familial amyloidotic polyneuropathy patients.
New product development
Authors: Fojt Martin
Published: September 2012

In the hectic world in which we live it is all too easy to lose sight of our original goals. Day‐to‐day events take on an unprecedented amount of importance relative to our overall aims. What people need more of is an overview of what they are doing to enable clarity and perspective to shine through. Easier said than done, I hear you say, and you are probably right. This special issue of British Food Journal, on the theme of new product development, aims to add perspective by adding a selection of articles on how other industries manage this most important of areas.
Comparing the van Oosterhout and Chybicki‐Burczyk methods of estimating null allele frequencies for inbred populations
Authors: Campagne P. , Smouse P. E. , Varouchas G. , Silvain J.‐F. , Leru B.
Published: September 2012

In spite of the usefulness of codominant markers in population genetics, the existence of null alleles raises challenging estimation issues in natural populations that are characterized by positive inbreeding coefficients (F > 0). Disregarding the possibility of F > 0 in a population will generally lead to overestimates of null allele frequencies. Conversely, estimates of inbreeding coefficients (F) may be strongly biased upwards (excess homozygotes), in the presence of nontrivial frequencies of null alleles. An algorithm has been presented for the estimation of null allele frequencies in inbred populations (van Oosterhout method), using external estimates of the F‐statistics. The goal of this study is to introduce a modification of this method and to provide a formal comparison with an alternative likelihood‐based method (Chybicki‐Burczyk). Using simulated data, we illustrate the strengths and limitations of these competing methods. Under most circumstances, the likelihood method is preferable, but for highly inbred organisms, a modified van Oosterhout method offers some advantages.