bluuebunny/crossref_metadata_2025 huggingface dataset:
Exergy optimization of domestic solar cylindrical-parabolic cooker
Authors: Nemati H. , Javanmardi M. J.
Published: December 2012

Solar parabolic cooker (SPC) is a simple and an inexpensive equipment which may be used extensively in domestic applications. However, as it is shown in this paper, the 1st law efficiency is very low and the 2nd law efficiency is even lower. For this reason, the performance optimization of cooker is necessary. This optimum performance may be achieved at a specific working temperature. In this paper, the optimization was performed on more than 400 different cases and a simple but useful correlation was proposed to determine the optimum working temperature. It is clear that this optimum temperature in turn, determines the cooker length or fluid mass flow rate.
Magnetic instability in a dilute circular rarefaction wave
Authors: Dieckmann M. E. , Sarri G. , Borghesi M.
Published: December 2012

The growth of magnetic fields in the density gradient of a rarefaction wave has been observed in simulations and in laboratory experiments. The thermal anisotropy of the electrons, which gives rise to the magnetic instability, is maintained by the ambipolar electric field. This simple mechanism could be important for the magnetic field amplification in astrophysical jets or in the interstellar medium ahead of supernova remnant shocks. The acceleration of protons and the generation of a magnetic field by the rarefaction wave, which is fed by an expanding circular plasma cloud, is examined here in form of a 2D particle-in-cell simulation. The core of the plasma cloud is modeled by immobile charges, and the mobile protons form a small ring close to the cloud's surface. The number density of mobile protons is thus less than that of the electrons. The protons of the rarefaction wave are accelerated to 1/10 of the electron thermal speed, and the acceleration results in a thermal anisotropy of the electron distribution in the entire plasma cloud. The instability in the rarefaction wave is outrun by a TM wave, which grows in the dense core distribution, and its magnetic field expands into the rarefaction wave. This expansion drives a secondary TE wave.
Dynamics and pulse-package oscillations in broad-area semiconductor lasers with short optical feedback
Authors: Takeda Akira , Shogenji Rui , Ohtsubo Junji
Published: December 2012

Pulse-package oscillations in broad-area semiconductor lasers subjected to short optical feedback are experimentally observed. The pulse-package oscillation consists of a frequency component that corresponds to an external optical feedback loop with an envelop of periodic low-frequency fluctuations. However, the periodicity induced by optical feedback does not always improve the time-averaged beam profiles of the laser oscillations. We also investigated time-averaged near-field beam profiles in relation with the optical feedback dynamics.
Nanosecond pulsed laser blackening of copper
Authors: Tang Guang , Hourd Andrew C. , Abdolvand Amin
Published: December 2012

Nanosecond (12 ns) pulsed laser processing of copper at 532 nm resulted in the formation of homogenously distributed, highly organized microstructures. This led to the fabrication of large area black copper substrates with absorbance of over 97% in the spectral range from 250 nm to 750 nm, and a broadband absorbance of over 80% between 750 nm and 2500 nm. Optical and chemical analyses of the fabricated black metal are presented and discussed. The employed laser is an industrially adaptable source and the presented technique for fabrication of black copper could find applications in broadband thermal radiation sources, solar energy absorbers, irradiative heat transfer devices, and thermophotovoltaics.
Piezoresistance behaviors of ultra-strained SiC nanowires
Authors: Shao Ruiwen , Zheng Kun , Zhang Yuefei , Li Yujie , Zhang Ze , Han Xiaodong
Published: December 2012

In situ electrical measurement experiments were carried out in individual SiC nanowires (NWs) subjected to tensile strain using a transmission electron microscope. Fracture strain approaching 10% was achieved for a diamond-structure SiC NW with a 〈111〉 direction. With an increase in the tensile strain, the conductance increased monotonously. The current rate of increase remained constant prior to fracture. The calculated piezoresistance coefficient of this SiC NW was −1.15 × 10−11 Pa−1, which is similar to the coefficient of the bulk material. Our results indicate that these SiC NWs can be used as pressure sensors even in very high-pressure environments.
Experimental verification of the 3-step model of photoemission for energy spread and emittance measurements of copper and CsBr-coated copper photocathodes suitable for free electron laser applications
Authors: Maldonado Juan R. , Pianetta Piero , Dowell David H. , Corbett Jeff , Park Sam , Schmerge John , Trautwein Ann , Clay William
Published: December 2012

This paper presents measurements and analysis of the quantum efficiency (QE) and intrinsic emittance of Cu and CsBr coated Cu photocathodes. The data analysis uses expressions for the quantum efficiency and the intrinsic emittance for metal cathodes previously derived from Spicer's three-step model of photoemission. Data taken with a 257 nm CW laser on (100) Cu crystals indicate an emittance of 0.77 (μm/mm-rms) for CsBr coated and 0.42 (μm/mm-rms) for uncoated cathodes. The high quantum efficiency and low emittance observed for CsBr coated cathodes have applications in free electron laser and other devices requiring high brightness electron beams.
Unusual growth of polycrystalline oxide film induced by negative ion bombardment in the capacitively coupled plasma deposition
Authors: Takayanagi S. , Yanagitani T. , Matsukawa M.
Published: December 2012

A polycrystalline film usually grows in its most densely packed plane parallel to the substrate plane. We demonstrated that the unusual crystalline growth can occur by using energetic negative ions generated in the magnetron capacitively coupled plasma deposition without using separated ion source. Negative ion energy and flux entering the substrate were quantitatively measured and compared with the preferential crystalline growth of unusual (112¯0) orientation in ZnO films. Strong (112¯0) orientation was found at the cathode erosion area where large amount of high energy negative ion of 170–250 eV was observed in low gas pressure of 0.1 Pa.
Controlled energy shuttling in terpolymers enabling independent optimization of absorption and transport properties in organic solar cell materials
Authors: Mangold Hannah , Howard Ian A. , Janietz Silvia , Laquai Frédéric
Published: December 2012

The optimization of current materials for organic solar cells is complicated by the fact that individual modifications concurrently affect several efficiency-limiting factors. For example, in donor-acceptor copolymers, the chemical optimization of the light absorption properties concurrently alters the charge transport properties and not necessarily in the desired direction. This interdependency frustrates step-wise optimization of materials for maximum power conversion efficiency. In this letter, we introduce a terpolymer which we demonstrate effectively decouples the light absorption and charge transport properties onto separate monomeric units, allowing each desired property to be independently tuned in the material and opening an avenue for step-wise, material-design-based optimization of organic solar cell quantum efficiency.
Reducing the effect of Metropolization on mixing times in molecular dynamics simulations
Authors: Wagoner Jason A. , Pande Vijay S.
Published: December 2012

Molecular dynamics algorithms are subject to some amount of error dependent on the size of the time step that is used. This error can be corrected by periodically updating the system with a Metropolis criterion, where the integration step is treated as a selection probability for candidate state generation. Such a method, closely related to generalized hybrid Monte Carlo (GHMC), satisfies the balance condition by imposing a reversal of momenta upon candidate rejection. In the present study, we demonstrate that such momentum reversals can have a significant impact on molecular kinetics and extend the time required for system decorrelation, resulting in an order of magnitude increase in the integrated autocorrelation times of molecular variables for the worst cases. We present a simple method, referred to as reduced-flipping GHMC, that uses the information of the previous, current, and candidate states to reduce the probability of momentum flipping following candidate rejection while rigorously satisfying the balance condition. This method is a simple modification to traditional, automatic-flipping, GHMC methods and significantly mitigates the impact of such algorithms on molecular kinetics and simulation mixing times.
Mitigating residual stress in Cu metallization
Authors: Murray Conal E. , Jordan-Sweet Jean , Todd Ryan E. , Toney Michael F.
Published: December 2012

The application of a cryogenic thermal excursion to passivated copper films has been demonstrated to dramatically reduce the magnitude of residual stress and to induce compressive, in-plane stress at room temperature. In-situ x-ray diffraction measurements reveal the evolution of in-plane stress within SiCxNyHz and TaN capped Cu films, which undergo significant plastic behavior on cooling and as the film approaches room temperature during heating. The resulting compressive stress represents a more favorable condition to mitigate voiding within the metallization. In-situ and ex-situ measurements of SiCxNyHz capped Cu films reveal that the final stress state is independent of cooling rate.
Self-proton/ion radiography of laser-produced proton/ion beam from thin foil targets
Authors: Paudel Y. , Renard-Le Galloudec N. , Nicolai Ph. , d'Humieres E. , Ya. Faenov A. , Kantsyrev V. L. , Safronova A. S. , Shrestha I. , Osborne G. C. , Shlyaptseva V. V. , Sentoku Y.
Published: December 2012

Protons and multicharged ions generated from high-intensity laser interactions with thin foil targets have been studied with a 100 TW laser system. Protons/ions with energies up to 10 MeV are accelerated either from the front or the rear surface of the target material. We have observed for the first time that the protons/ions accelerated from the front surface of the target, in a direction opposite to the laser propagation direction, are turned around and pulled back to the rear surface, in the laser propagation direction. This proton/ion beam is able to create a self-radiograph of the target and glass stalk holding the target itself recorded through the radiochromic film stack. This unique result indicates strong long-living (ns time scale) magnetic fields present in the laser-produced plasma, which are extremely important in energy transport during the intense laser irradiation. The magnetic field from laser main pulse expands rapidly in the preformed plasma to rotate the laser produced protons. Radiation hydrodynamic simulations and ray tracing found that the magnetic field created by the amplified spontaneous emission prepulse is not sufficient to explain the particle trajectories, but the additional field created by the main pulse interaction estimated from particle-in-cell simulation is able to change the particle trajectories.
The effect of carbon nanotube/organic semiconductor interfacial area on the performance of organic transistors
Authors: Kang Narae , Sarker Biddut K. , Khondaker Saiful I.
Published: December 2012

We show that the performance of pentacene transistors can be significantly improved by maximizing the interfacial area at single walled carbon nanotube (SWCNT)/pentacene. The interfacial areas are varied by anchoring short SWCNTs of different densities (0–30/μm) to the Pd electrodes. The average mobility is increased three, six, and nine times for low, medium, and high SWCNT densities, respectively, compared to the devices with zero SWCNT. The current on-off ratio and on-current are increased up to 40 times and 20 times with increasing the SWCNT density. We explain the improved device performance using reduced barrier height of SWCNT/pentacene interface.
Fish scale terrace GaInN/GaN light-emitting diodes with enhanced light extraction
Authors: Stark Christoph J. M. , Detchprohm Theeradetch , Zhao Liang , Paskova Tanya , Preble Edward A. , Wetzel Christian
Published: December 2012

Non-planar GaInN/GaN light-emitting diodes were epitaxially grown to exhibit steps for enhanced light emission. By means of a large off-cut of the epitaxial growth plane from the c-plane (0.06° to 2.24°), surface morphologies of steps and inclined terraces that resemble fish scale patterns could controllably be achieved. These patterns penetrate the active region without deteriorating the electrical device performance. We find conditions leading to a large increase in light-output power over the virtually on-axis device and over planar sapphire references. The process is found suitable to enhance light extraction even without post-growth processing.
Self-heating effects on the electrical instability of fully printed p-type organic thin film transistors
Authors: Rapisarda M. , Fortunato G. , Valletta A. , Jacob S. , Benwadih M. , Coppard R. , Chartier I. , Mariucci L.
Published: December 2012

Bias stress instability has been investigated in printed p-channel organic thin film transistors. The observed instability is related to two mechanisms: one, dominating at low T and causing “mobile ions” like threshold voltage variations is probably due to creation/annihilation of acceptor-like states; the second one, causing charge-trapping like instability, dominates at high T. High drain voltage bias stress experiments, inducing device self-heating, present threshold voltage variations, suggest a channel temperature rise ranging from 50 to 60 °C. The results point out the role of self-heating on the bias-stress instability, which is related to a combination of bias and temperature conditions.
Arbitrary amplitude dust ion acoustic solitary waves in a magnetized suprathermal dusty plasma
Authors: Shahmansouri M. , Alinejad H.
Published: December 2012

The linear and nonlinear dust-ion-acoustic (DIA) wave propagating obliquely with respect to an external magnetic field is studied in a magnetized complex plasma which consists of a cold ion fluid, superthermal electrons, and static dust particles. The propagation properties of two possible modes (in the linear regime) are investigated. It is found that the electron suprathermality and the electron population decrease the phase velocities of both modes, while obliqueness leads to increase of separation between two modes. An energy-like equation derived to describe the nonlinear evolution of DIA solitary waves. The influences of electron suprathermality, obliqueness, and electron population on the existence domain of solitary waves and the soliton characteristics are examined. It is shown that the existence domain of the DIA soliton and its profile are significantly depending on the deviation of electrons from thermodynamic equilibrium, electrons population, and obliqueness. It is also found that the suprathermal plasma supports the DIA solitons with larger amplitude.
A method for determining the specific capacitance value of mesoscopic Josephson junctions
Authors: Yeh Sheng-Shiuan , Chen Kuan-Wen , Chung Tao-Hsiang , Wu Dai-Yang , Lin Ming-Chou , Wang Jyh-Yang , Ho I-Lin , Wu Cen-Shawn , Kuo Watson , Chen ChiiDong
Published: December 2012

An approach for precise determination of capacitance values and energy level spacing of mesoscopic Josephson junctions is proposed. Quantized levels arising from plasma oscillation manifest themselves in the current peaks in the current-voltage characteristics of a nearby probe Josephson junction. From peak spacing, the specific capacitance of aluminum junctions is determined to be 35 fF/μm2. In addition, magnetic field dependence of quantum states can be described quantitatively by a theory that takes the effect of field induced surface current into account.
Unique thrombin inhibition mechanism by anophelin, an anticoagulant from the malaria vector
Authors: Figueiredo Ana C. , de Sanctis Daniele , Gutiérrez-Gallego Ricardo , Cereija Tatiana B. , Macedo-Ribeiro Sandra , Fuentes-Prior Pablo , Pereira Pedro José Barbosa
Published: December 2012

Anopheles
mosquitoes are vectors of malaria, a potentially fatal blood disease affecting half a billion humans worldwide. These blood-feeding insects include in their antihemostatic arsenal a potent thrombin inhibitor, the flexible and cysteine-less anophelin. Here, we present a thorough structure-and-function analysis of thrombin inhibition by anophelin, including the 2.3-Å crystal structure of the human thrombin·anophelin complex. Anophelin residues 32–61 are well-defined by electron density, completely occupying the long cleft between the active site and exosite I. However, in striking contrast to substrates, the D50-R53 anophelin tetrapeptide occupies the active site cleft of the enzyme, whereas the upstream residues A35-P45 shield the regulatory exosite I, defining a unique reverse-binding mode of an inhibitor to the target proteinase. The extensive interactions established, the disruption of thrombin’s active site charge–relay system, and the insertion of residue R53 into the proteinase S
1
pocket in an orientation opposed to productive substrates explain anophelin’s remarkable specificity and resistance to proteolysis by thrombin. Complementary biophysical and functional characterization of point mutants and truncated versions of anophelin unambiguously establish the molecular mechanism of action of this family of serine proteinase inhibitors (I77). These findings have implications for the design of novel antithrombotics.
Protein kinase N1, a cell inhibitor of Akt kinase, has a central role in quality control of germinal center formation
Authors: Yasui Teruhito , Sakakibara-Yada Kaori , Nishimura Taki , Morita Kentaro , Tada Satoru , Mosialos George , Kieff Elliott , Kikutani Hitoshi
Published: December 2012

Germinal centers (GCs) are specialized microenvironments in secondary lymphoid organs where high-affinity antibody-producing B cells are selected based on B-cell antigen receptor (BCR) signal strength. BCR signaling required for normal GC selection is uncertain. We have found that protein kinase N1 (PKN1, also known as PRK1) negatively regulates Akt kinase downstream of the BCR and that this regulation is necessary for normal GC development. PKN1 interacted with and inhibited Akt1 kinase and transforming activities.
Pkn1
−/−
B cells were hyperresponsive and had increased phosphorylated Akt1 levels upon BCR stimulation. In the absence of immunization or infection,
Pkn1
−/−
mice spontaneously formed GCs and developed an autoimmune-like disease with age, which was characterized by autoantibody production and glomerulonephritis. More B cells, with fewer somatic BCR gene V region hypermutations were selected in
Pkn1
−/−
GCs. These results indicate that PKN1 down-regulation of BCR-activated Akt activity is critical for normal GC B-cell survival and selection.
Shi‘ite Women's Seminaries (howzeh-ye ‘elmiyyeh-ye khahran) in Iran: Possibilities and Limitations
Authors: Sakurai Keiko
Published: December 2012

The establishment of Jami‘at al-Zahra, the first official female seminary in post-revolutionary Iran, opened new possibilities for women to enter the male-dominated clerical hierarchy. The rapid growth of female seminaries increased the presence of seminary-educated women in the official religious sphere. However, as opposed to the male seminaries whose dominant role is to train mojtaheds who can issue a competent legal opinion, the primary role of female seminaries is to train educators and propagandists. Drawing on interviews, documents issued by seminaries and secondary sources, this paper concludes that in spite of the rapid growth of female seminaries, very few women reach the rank of a mojtahed, and thus, in no way weaken the male-centric seminary system in contemporary Iran.
Randomized Trial of Web-Based Training to Promote Counselor Use of Cognitive Behavioral Therapy Skills in Client Sessions
Authors: Larson Mary Jo , Amodeo Maryann , LoCastro Joseph S. , Muroff Jordana , Smith Lauren , Gerstenberger Eric
Published: December 2012

Background and Methods: The authors designed and delivered an innovative Web course on cognitive behavioral therapy (CBT), a specific empirically based treatment, to a diverse group of addiction counselors and supervisors in 54 addiction units across the country, and conducted a randomized controlled trial of its effectiveness with 127 counselors. The primary focus of the trial was to assess “adequate adherence to CBT practice” after training as judged by raters blinded to training condition who listened to audiotapes of actual client sessions. Counselors who passed were judged to satisfy 2 criteria: (a) low pass or greater on at least 1 of 3 “CBT-generic skills” assessing session structure; and (b) low pass or greater on at least 1 of 3 “CBT-specific skills” related to use of functional analysis, cognitive skills practice, or behavioral skills practice. Results: Although the counselors’ use of CBT skills in sessions increased after Web course training, it was not statistically significant and not larger than the gain of control-group counselors trained with a written CBT manual.
The Vicious Circle
Authors: Mieriņa Inta
Published: December 2012

The reaction of citizens deeply disappointed with their government and its decisions differs from country to country, and in some cases, such as Latvia during the recent economic crisis, has been surprisingly passive. In this paper I argue that political passivity can be partly explained by psychological mechanisms triggered by constant under-performance and unresponsiveness of political authorities. Using International Social Survey Program 2006–2007 data, I construct a structural equation model which shows that government's performance can facilitate or hinder the development of civil society through its impact on (1) a sense of political efficacy, (2) political competence, and (3) interpersonal trust. Poor institutional performance and the following loss of trust in political authorities has a negative effect on people's perceptions of politics, of themselves and of each other, discouraging further engagement in all kinds of political activities. Considering the importance of civic participation for the quality of governance this creates a vicious circle which might not be easy to break. Finally, several theoretical perspectives are discussed that help to explain the formation and persistence of the vicious circle.
Show Me the Honey! Effects of Social Exclusion on Financial Risk-Taking
Authors: Duclos Rod , Wan Echo Wen , Jiang Yuwei
Published: December 2012

This research examines the effects of social exclusion on a critical aspect of consumer behavior, financial decision-making. Specifically, four lab experiments and one field survey uncover how feeling isolated or ostracized causes consumers to pursue riskier but potentially more profitable financial opportunities. These daring proclivities do not appear driven by impaired affect or self-esteem. Rather, interpersonal rejection exacerbates financial risk-taking by heightening the instrumentality of money (as a substitute for popularity) to obtain benefits in life. Invariably, the quest for wealth that ensues tends to adopt a riskier but potentially more lucrative road. The article concludes by discussing the implications of its findings for behavioral research as well as for societal and individual welfare.
Magnetic heterostructures with low coercivity for high-performance magneto-optic devices
Authors: Kotov V A , Popkov A F , Soloviev S V , Vasiliev M , Alameh K , Nur-E-Alam M , Balabanov D E
Published: December 2012

In this work, we analyse the method of forming magneto-optically active heterostructures based on magnetic layers with different magnetic properties. Layers of one type possess a high effective constant of uniaxial magnetic anisotropy

for which the condition

is fulfilled, where K
u is the constant of uniaxial magnetic anisotropy and

is the demagnetizing energy, and layers of the second type used possess in-plane or quasi-in-plane magnetization, in which the condition

holds true. The layers of the first type, which we refer to as layers of positive effective uniaxial magnetic anisotropy, may have the composition Bi2Dy1Fe4Ga1O12 and the layers of second type the composition Bi3Fe5O12, which may have very high magneto-optic (MO) figure of merit and are therefore very attractive for the development of MO transparencies and ultra-fast switches. We discuss the optimization of triple-layer structure parameters aimed at achieving a high MO figure of merit simultaneously with low coercivity and high remanent magnetization and possessing rectangular hysteresis loops. The results of the experimental study of the MO properties achieved in garnet heterostructures fabricated using RF sputtering are also described. We show that the proposed paradigm of using new magnetic material combinations demonstrating significantly improved magnetic and MO properties may be realized when working with heterostructures based on Bi-substituted ferrite garnets grown on (1 1 1)-oriented garnet substrates.
Characteristics of ZnO : As/GaN heterojunction diodes obtained by PA-MBE
Authors: Przezdziecka E , Wierzbicka A , Reszka A , Goscinski K , Droba A , Jakiela R , Dobosz D , Krajewski T A , Kopalko K , Sajkowski J M , Stachowicz M , Pietrzyk M A , Kozanecki A
Published: December 2012

We report on the characterization of wide-band-gap heterojunction diodes based on the p-ZnO/n-GaN material system. The layer structure consists of 11 µm GaN on sapphire substrates and As-doped ZnO film of thickness 0.4 µm obtained by plasma-assisted molecular beam epitaxy (PA-MBE). The quality of the heterojunction was examined by x-ray diffraction, atomic force microscopy and scanning electron microscopy. The arsenic concentration in ZnO, measured by secondary ion mass spectroscopy (SIMS), is 5 × 1020 cm−3. The maximum forward-to-reverse current ratio I
F/I
R is of about 105 in the applied voltage ±3 V, a very good result for this type of heterojunction.
The effect of various solvents on the back channel of solution-processed In–Ga–Zn–O thin-film transistors intended for biosensor applications
Authors: Kim Si Joon , Jung Joohye , Yoon Doo Hyun , Kim Hyun Jae
Published: December 2012

This study investigated the effects of exposing solution-processed In–Ga–Zn–O (IGZO) thin-film transistors (TFTs), intended for biosensor applications, to various solvents. Various solvents, such as the nonpolar solvent chlorobenzene and the polar solvents ethanol and deionized (DI) water, were dropped and adsorbed on exposed IGZO channel surfaces. All IGZO TFT devices exhibited a negative threshold voltage shift and a sub-threshold swing degradation, without an accompanying degradation in field-effect mobility. These variations depended on the dielectric constant of the solvents; with the exception of the IGZO TFT device exposed to DI water, they all gradually returned to their initial states.
Multiscale analysis of adsorption-induced surface stress of alkanethiol on microcantilever
Authors: Chen Chuin-Shan , Chou Chia-Ching , Chang Shu-Wei
Published: December 2012

A multiscale scheme was developed to evaluate adsorption-induced surface stresses in an alkanethiol-passivated Au(1 1 1)-modified microcantilever surface using first-principle density-functional theory calculations. In particular, the effect of alkyl chain length on the generated surface stresses was considered in detail. It was found that the majority of the surface stress originated from re-organization of the first two Au atom layers that lie in close proximity to the adsorption site. The difference in the calculated surface stresses, which were consistent with experimental measurements, was determined to be approximately −0.05 N m−1 per two carbons added to the alkanethiol chain.
Coefficients of sliding friction of single crystals of high explosives under different rubbing conditions
Authors: Wu Y Q , Chaudhri M Munawar
Published: December 2012

The coefficients of sliding friction of single crystals of commonly used high explosives pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX) and beta-cyclotetramethylene tetranitramine (β-HMX) under several rubbing configurations and at a relative sliding speed of 0.22 mm s−1were measured. The sliding configurations were (1) crystal–polished steel pairs, (2) like-crystal pairs and (3) unlike-crystal pairs. For every rubbing configuration the friction force showed oscillations, which are thought to be caused by the formation and shearing of the adhesive junctions formed at the surface of the rubbing crystals. This shearing of the adhesive junctions led to the formation of microscopic and sub-microscopic particles, which were confirmed by an environmental scanning electron microscope study. For every rubbing configuration and for relatively high normal loads pressing the rubbing crystals together, the coefficient of friction was generally in the range 0.2–0.25 and it has been concluded that the coefficient of friction is controlled by the adhesion with almost negligible contribution from the ploughing component. From a knowledge of the coefficient of friction and the uniaxial yield stress values of single crystals of RDX andβ-HMX, the shear strength of these crystals were determined to be ∼13.4 MPa and ∼16.8 MPa, respectively.
Synthesis and characterization of nano- and microcrystalline cubes of pure and Ag-doped LiF
Authors: Alharbi Najlaa D , Salah Numan , Habib Sami S , Alarfaj Esam
Published: December 2012

Lithium fluoride (LiF) produced in single crystals and doped with proper activators is a highly sensitive phosphor used in several applications such as integrated optics, colour centre laser and radiation dosimetry. In this work, we have developed a new synthetic chemical co-precipitation route for the synthesis of well-crystallized micro- and nanocrystalline cubes of pure and silver (Ag)-doped LiF. The as-synthesized samples were characterized by x-ray diffraction (XRD), scanning electron microscopy, absorption spectrum, photoluminescence (PL) and Raman spectroscopy. Size of the produced cubes could be controlled in the range 10 µm–50 nm by varying the solvent : co-solvent ratio. Micro-sized cubes could be grown in the presence of water as a solvent, while ethanol, which acts as a co-solvent, is found to be effective in reducing the size to the nanoscale. XRD results show complete crystalline structures in a griceite phase. The PL result of pure nanocubes exhibits a broad band in the range 370–550 nm, while that doped with Ag shows a prominent band at 420 nm. Raman spectra of the pure and Ag-doped LiF samples display several bands located in the range 80–236 cm−1. These results show that pure nanocubes of LiF have active colour centres without irradiation, which could be enhanced/modified by Ag dopants. This implies that these nanocubes might be useful in the development of optical devices.
Characterization and antimicrobial efficacy against E. coli of a helium/air plasma at atmospheric pressure created in a plastic package
Authors: Connolly J , Valdramidis V P , Byrne E , Karatzas K A , Cullen P J , Keener K M , Mosnier J P
Published: December 2012

A plasma source, sustained by the application of a floating high voltage (±15 kV) to parallel-plate electrodes at 50 Hz, has been achieved in a helium/air mixture at atmospheric pressure (P = 105 Pa) contained in a zip-locked plastic package placed in the electrode gap. Some of the physical and antimicrobial properties of this apparatus were established with a view to ascertain its performance as a prototype for the disinfection of fresh produce. The current–voltage (I–V) and charge–voltage (Q–V) characteristics of the system were measured as a function of gap distance d, in the range (3 × 103 ⩽ Pd ⩽ 1.0 × 104 Pa m). The electrical measurements showed this plasma source to exhibit the characteristic behaviour of a dielectric barrier discharge in the filamentary mode and its properties could be accurately interpreted by the two-capacitance in series model. The power consumed by the discharge and the reduced field strength were found to decrease quadratically from 12.0 W to 4.5 W and linearly from 140 Td to 50 Td, respectively, in the range studied. Emission spectra of the discharge were recorded on a relative intensity scale and the dominant spectral features could be assigned to strong vibrational bands in the 2+ and 1− systems of N2 and

, respectively, with other weak signatures from the NO and OH radicals and the N+, He and O atomic species. Absolute spectral intensities were also recorded and interpreted by comparison with the non-equilibrium synthetic spectra generated by the computer code SPECAIR. At an inter-electrode gap of 0.04 m, this comparison yielded typical values for the electron, vibrational and translational (gas) temperatures of (4980 ± 100) K, (2700 ± 200) K and (300 ± 100) K, respectively and an electron density of 1.0 × 1017 m−3. A Boltzmann plot also provided a value of (3200 ± 200 K) for the vibrational temperature. The antimicrobial efficacy was assessed by studying the resistance of both Escherichia coli K12 its isogenic mutants in soxR, soxS, oxyR, rpoS and dnaK selected to identify possible cellular responses and targets related with 5 min exposure to the active gas in proximity of, but not directly in, the path of the discharge filaments. Both the parent strain and mutants populations were significantly reduced by more than 1.5 log cycles in these conditions, showing the potential of the system. Post-treatment storage studies showed that some transcription regulators and specific genes related to oxidative stress play an important role in the E. coli repair mechanism and that plasma exposure affects specific cell regulator systems.
Mini-Oort clouds: compact isotropic planetesimal clouds from planet–planet scattering
Authors: Raymond Sean N. , Armitage Philip J.
Published: December 2012

Starting from planetary systems with three giant planets and an outer disc of planetesimals, we use dynamical simulations to show how dynamical instabilities can transform planetesimal discs into 102–103 au-scale isotropic clouds. The instabilities involve a phase of planet–planet scattering that concludes with the ejection of one or more planets and the inward-scattering of the surviving gas giant(s) to remove them from direct dynamical contact with the planetesimals. ‘Mini-Oort clouds’ are thus formed from scattered planetesimals whose orbits are frozen by the abrupt disappearance of the perturbing giant planet. Although the planetesimal orbits are virtually isotropic, the surviving giant planets tend to have modest inclinations (typically ∼10°) with respect to the initial orbital plane. The collisional lifetimes of mini-Oort clouds are long (10 Myr to >10 Gyr) and there is a window of ∼100 Myr or longer during which they produce spherical clouds of potentially observable dust at 70 μm. If the formation channel for hot Jupiters commonly involves planetary close encounters, we predict a correlation between this subset of extrasolar planetary systems and mini-Oort clouds.
Human papillomavirus type 38 E6 and E7 act as tumour promoters during chemically induced skin carcinogenesis
Authors: Viarisio Daniele , Decker Karin Müller , Aengeneyndt Birgit , Flechtenmacher Christa , Gissmann Lutz , Tommasino Massimo
Published: December 2012

Many findings support a possible involvement of a subgroup of human papillomaviruses (HPVs), called cutaneous beta HPV types, in the development of non-melanoma skin cancer. The skin of transgenic (Tg) mice expressing viral oncoproteins E6 and E7 from different cutaneous beta HPV types, including HPV38, showed an increased susceptibility to UV-induced and/or chemically induced skin carcinogenesis compared with wild-type animals. In this study, we show that beta HPV38 E6 and E7 oncoproteins act as promoter and progression factors in multi-stage skin carcinogenesis, strongly cooperating with the initiator and DNA damage agent 7,12-dimethylbenz[a]anthracene. In contrast, exposure of HPV38 E6/E7 Tg mice to the promoter 12-O-tetradecanoylphorbol-13-acetate did not significantly result in the development of skin lesions. These findings further support the role of beta HPV types in skin carcinogenesis, providing additional insight into their precise contribution to the multi-step process.
Pustular‐type drug‐induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms due to carbamazepine with systemic muscle involvement
Authors: Matsuda Haruna , Saito Kanami , Takayanagi Yoshikazu , Okazaki Toshio , Kashima Kenji , Ishikawa Kazushi , Kai Yoshitaka , Takeo Naoko , Hatano Yutaka , Okamoto Osamu , Fujiwara Sakuhei
Published: December 2012

Drug‐induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe reaction usually associated with maculopapular eruptions and systemic involvement. Here we report the first case, to our knowledge, of DIHS/DRESS due to carbamazepine with acute generalized pustular bacterid‐like (AGPB‐like) eruptions and skeletal muscle involvement. Reviewing our case and the published work, we discuss pustular‐type DIHS/DRESS which, in most cases, involves acute generalized exanthematous pustulosis (AGEP)‐like skin eruptions in response to carbamazepine. Pustular eruptions may appear in relatively few cases of DIHS/DRESS, in particular, when the causative drug is carbamazepine and, even in cases of intractable pustular bacterid‐like eruptions, a reaction to a drug should be suspected. Skeletal muscle involvement may be associated with DIHS/DRESS as one of its systemic manifestations.
Anti‐topoisomerase I antibody levels as serum markers of skin sclerosis in systemic sclerosis
Authors: Hasegawa Minoru , Imura‐Kumada Sayako , Matsushita Takashi , Hamaguchi Yasuhito , Fujimoto Manabu , Takehara Kazuhiko
Published: December 2012

The aim of the present study was to clarify the clinical significance of anti‐topoisomerase I antibody (Ab) levels in Japanese patients with systemic sclerosis (SSc). Using immunoprecipitation assays and enzyme‐linked immunoassay (ELISA), anti‐topoisomerase I Ab was detected in 53 SSc patients who visited Kanazawa University Hospital between 2001 and 2010. In these patients, the association between serum anti‐topoisomerase I Ab levels measured with ELISA and clinical features were compared using univariate analysis and multiple regression analysis. There were significantly positive correlations between anti‐topoisomerase I Ab levels and the modified Rodnan total skin thickness score (MRSS) and skin thickness progression rate, and a significantly negative correlation with disease duration. On the other hand, anti‐topoisomerase I Ab levels were not significantly associated with other clinical features including lung involvement. In a longitudinal study, anti‐topoisomerase I Ab levels were decreased significantly in patients that had decreased MRSS, but not in patients that had unchanged or increased MRSS. There was a significantly positive association between anti‐topoisomerase I Ab levels and MRSS and a significantly negative association with disease duration by multiple regression analysis. Our findings suggest that serum levels of anti‐topoisomerase I Ab reflect the severity of skin sclerosis in patients with SSc.
Exploring the mesofilter as a novel operational scale in conservation planning
Authors: Crous Casparus J. , Samways Michael J. , Pryke James S.
Published: December 2012

Increased emphasis is being placed on developing effective biodiversity conservation tools for practical conservation planning. The mesofilter is such a biodiversity planning tool, but has yet to be fully explored to appreciate its effectiveness. The key premise of the mesofilter is that ecosystems contain certain physical elements that are specifically associated with a diversity of species. Identifying such mesofilters could therefore complement existing conservation planning tools such as coarse and fine filters.

To explore the value of the mesofilter as an operational scale in conservation planning, we studied 18 remnant patches of endangered montane grassland in KwaZulu‐Natal, South Africa, using the physical landscape feature of patch rockiness as an abiotic surrogate for biodiversity. The objective was to determine whether the mesofilter of rockiness can predict variation in species richness and composition for three dominant grassland taxa (plants, butterflies and grasshoppers) at the landscape scale.

Variable levels of rockiness had significant interactions with all three focal taxa. Higher species richness of all taxa was closely associated with higher levels of rockiness in a patch. The rocky mesofilter only predicted significant differences in species composition for butterflies. Elevation was also important, possibly another mesofilter for plants and grasshoppers in this landscape.

Synthesis and applications. The results indicate that the use of an abiotic surrogate such as rockiness can predict biodiversity value across multiple taxa. The mesofilter is therefore a valuable surrogacy and congruency tool for practical biodiversity conservation across this landscape and would likely have similar value if explored elsewhere. It also has value in the design and management of protected areas.
Comparative community gene expression analysis of Aquificales‐dominated geothermal springs
Authors: Hamamura Natsuko , Meneghin Jennifer , Reysenbach Anna‐Louise
Published: December 2012

Members of Sulfurihydrogenibium are often observed as visible filamentous biomass in circumneutral hot springs and play roles in sulfur‐cycling, hydrogen oxidation and iron mineralization. To gain insight into the ecophysiology of Sulfurihydrogenibium populations, we conducted preliminary metatranscriptomic analysis of three distinct thermal springs; Calcite Springs (YNP‐CS) and Mammoth Springs (YNP‐MHS) in Yellowstone National Park, USA, and Furnas Springs (AZ) in Azores, Portugal. Genes to which transcripts were assigned revealed commonly expressed functions among the sites, while several differences were also observed. All three sites, Sulfurihydrogenibium spp. dominate and are obtaining energy via metabolism of sulfur compounds under microaerophilic conditions. Cell motility was one of the expressed functions in two sites (YNP‐CS and AZ) with slower stream flow rates and thicker well‐formed biofilms. The transcripts from YNP‐CS and ‐MHS exhibited varying levels of sequence divergence from the reference genomes and corresponding metagenomes, suggesting the presence of microdiversity among Sulfurihydrogenibium populations in situ. Conversely, the majority of the AZ transcripts were identical to the S. azorense genome. Our initial results show that the metatranscriptomes in these similar Aquificales‐dominated communities can reveal community‐level gene function in geochemically distinct thermal environments.
Type II toxin/antitoxin MqsR/MqsA controls type V toxin/antitoxin GhoT/GhoS
Authors: Wang Xiaoxue , Lord Dana M. , Hong Seok Hoon , Peti Wolfgang , Benedik Michael J. , Page Rebecca , Wood Thomas K.
Published: December 2012

Toxin endoribonucleases of toxin/antitoxin (TA) systems regulate protein production by selectively degrading mRNAs but have never been shown to control other TA systems. Here we demonstrate that toxin MqsR of the MqsR/MqsA system enriches toxin ghoT mRNA in vivo and in vitro, since this transcript lacks the primary MqsR cleavage site 5′‐GCU. GhoT is a membrane toxin that causes the ghost cell phenotype, and is part of a type V TA system with antitoxin GhoS that cleaves specifically ghoT mRNA. Introduction of MqsR primary 5′‐GCU cleavage sites into ghoT mRNA reduces ghost cell production and cell death likely due to increased degradation of the altered ghoT mRNA by MqsR. GhoT also prevents cell elongation upon the addition of low levels of ampicillin. Therefore, during stress, antitoxin GhoS mRNA is degraded by toxin MqsR allowing ghoT mRNA translation to yield another free toxin that forms ghost cells and increases persistence. Hence, we show that GhoT/GhoS is the first TA system regulated by another TA system.
Fluxomics – connecting ‘omics analysis and phenotypes
Authors: Winter Gal , Krömer Jens O.
Published: December 2012

In our modern ‘omics era, metabolic flux analysis (fluxomics) represents the physiological counterpart of its siblings transcriptomics, proteomics and metabolomics. Fluxomics integrates in vivo measurements of metabolic fluxes with stoichiometric network models to allow the determination of absolute flux through large networks of the central carbon metabolism. There are many approaches to implement fluxomics including flux balance analysis (FBA), 13C fluxomics and 13C‐constrained FBA as well as many experimental settings for flux measurement including dynamic, stationary and semi‐stationary. Here we outline the principles of the different approaches and their relative advantages. We demonstrate the unique contribution of flux analysis for phenotype elucidation using a thoroughly studied metabolic reaction as a case study, the microbial aerobic/anaerobic shift, highlighting the importance of flux analysis as a single layer of data as well as interlaced in multi‐omics studies.
Politics of childcare policy beyond the left–right scale: Post‐industrialisation, transformation of party systems and welfare state restructuring
Authors: Hieda Takeshi
Published: December 2012

Childcare policy has become an integral part of social and economic policy in post‐industrial democracies. This article explores how the transformation of party systems structures the politics of childcare policy. It reveals that political parties contend with each other over childcare and female employment policy on the social‐value dimension as well as the redistributive dimension. Assuming that different party policies have distinct impacts on public childcare policy, it is hypothesised in this article that a government's policy position – composed of the governing parties' policy positions – affects changes in public spending for childcare services. Through an analysis of the pooled time‐series and cross‐section data of 18 advanced industrialised countries from 1980 until 2005 using multivariate regression methods, it is revealed that a government's redistributive left–right policy position interacts with its social liberal–conservative policy position, and that a left–liberal government raises its budget for childcare services while a left–conservative government does not.
Association between Traditional Nursing Home Quality Measures and Two Sources of Nursing Home Complaints
Authors: Troyer Jennifer L. , Sause Wendy
Published: December 2012

Objective

To test for an association between traditional nursing home quality measures and two sources of resident‐ and caregiver‐derived nursing home complaints.

Data Sources

Nursing home complaints to the North Carolina Long‐Term Care Ombudsman Program and state certification agency from October 2002 through September 2006 were matched with Online Survey Certification and Reporting data and Minimum Data Set Quality Indicators (MDS‐QIs).

Study Design

We examine the association between the number of complaints filed against a facility and measures of inspection violations, staffing levels, and MDS‐QIs.

Data Extraction

One observation per facility per quarter is constructed by matching quarterly data on complaints to OSCAR data from the same or most recent prior quarter and to MDS‐QIs from the same quarter. One observation per inspection is obtained by matching OSCAR data to complaint totals from both the same and the immediate prior quarter.

Principal Findings

There is little relationship between MDS‐QIs and complaints. Ombudsman complaints and inspection violations are generally unrelated, but there is a positive relationship between state certification agency complaints and inspection violations.

Conclusions

Ombudsman and state certification agency complaint data are resident‐ and caregiver‐derived quality measures that are distinctive from and complement traditional quality measures.