bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and analysis of the admittance characteristics of n+ metal-oxide-semiconductor capacitors with oxide and interface states - Gd0.25Ga0.15O0.6/Ga2O3 on In0.53Ga0.47As
Authors: Paterson G. W. , Holland M. C. , Thayne I. G. , Long A. R.
Published: April 2012

The 300-K admittance characteristics of n+ In0.53Ga0.47As MOS capacitors with a dielectric stack of Gd0.25Ga0.15O0.6/Ga2O3 in as-grown condition are examined in detail and compared to an oxide trap model that we previously introduced. The model explains many of the observed features not contained in the interface state model. By fitting the model to experimental data, we extract a distribution of defect states in space and energy within the oxide and at the oxide/semiconductor interface separately. Oxide states are the dominant defects over a wide range of energy. The defect state densities are not subject to the usual resolution limits of conventional analyses. Using this approach, it is possible to characterize relatively rapidly a wide range of energies at a single temperature without the need for reaching the low or high limits of frequency. The implications for the conventional interface state density (Dit) extraction techniques are explored. It is shown how oxide states can affect the extraction of sample parameters, particularly the insulator capacitance, and can result in a range of extracted Dit values. We believe these contribute to the wide range of Dit reported in the literature from similar admittance characteristics of a number of oxides on In0.53Ga0.47As.
Partial synchronization in stochastic dynamical networks with switching communication channels
Authors: Huang Chi , Ho Daniel W. C. , Lu Jianquan , Kurths Jürgen
Published: April 2012

In this paper, the partial synchronization problem of stochastic dynamical networks (SDNs) is investigated. Unlike the existing models, the SDN considered in this paper suffers from a class of communication constraint—only part of nodes’ states can be transmitted. Thus, less nodes’ states can be used to synchronize the SDN, which makes the analysis of the synchronization problem much harder. A set of channel matrices are introduced to reflect such kind of constraint. Furthermore, due to unpredictable environmental changes, the channel matrices can switch among some communication modes. The switching considered here is governed by a Markov process. To overcome the difficulty, a regrouping method is employed to derive our main results. The obtained conditions guarantee that partial synchronization can be achieved for SDNs under switching communication constraint. Finally, numerical examples are given to illustrate the effectiveness of the theoretical results and how the communication constraint influences synchronization result.
A comparison of methods for melting point calculation using molecular dynamics simulations
Authors: Zhang Yong , Maginn Edward J.
Published: April 2012

Accurate and efficient prediction of melting points for complex molecules is still a challenging task for molecular simulation, although many methods have been developed. Four melting point computational methods, including one free energy-based method (the pseudo-supercritical path (PSCP) method) and three direct methods (two interface-based methods and the voids method) were applied to argon and a widely studied ionic liquid 1-n-butyl-3-methylimidazolium chloride ([BMIM][Cl]). The performance of each method was compared systematically. All the methods under study reproduce the argon experimental melting point with reasonable accuracy. For [BMIM][Cl], the melting point was computed to be 320 K using a revised PSCP procedure, which agrees with the experimental value 337–339 K very well. However, large errors were observed in the computed results using the direct methods, suggesting that these methods are inappropriate for large molecules with sluggish dynamics. The strengths and weaknesses of each method are discussed.
The generalized block-localized wavefunction method: A case study on the conformational preference and C–O rotational barrier of formic acid
Authors: Jia Jian-Feng , Wu Hai-Shun , Mo Yirong
Published: April 2012

A Lewis structure corresponding to the most stable electron-localized state is often used as a reference for the measure of electron delocalization effect in the valence bond (VB) theory. As the simplest variant of ab initio VB theory, the generalized block-localized wavefunction (BLW) method defines the wavefunction for an electron-localized state with block-localized orbitals without the orthogonalization constraint on different blocks. The validity of the method can be critically examined with experimental evidences. Here the BLW method has been applied to the investigation of the roles of both the π conjugation and σ hyperconjugation effects in the conformational preference of formic acid for the trans (Z) conformer over the cis (E) conformer. On one hand, our computations showed that the deactivation of the π conjugation or σ hyperconjugation has little impact on the Z-E energy gap, thus neither is decisive and instead the local dipole-dipole electrostatic interaction between the carbonyl and hydroxyl groups is the key factor determining the Z-E energy gap. On the other hand, the present study supported the conventional view that π conjugation is largely responsible for the C–O rotation barrier in formic acid, though the existence of hyperconjugative interactions in the perpendicular structure lowers the barrier considerably.
Confinement effects on valence-subband character and polarization anisotropy in (112¯2) semipolar InGaN/GaN quantum wells
Authors: Roberts Christopher , Yan Qimin , Miao Mao-Sheng , Van de Walle Chris G.
Published: April 2012

We perform self-consistent Schrödinger-Poisson simulations on (112¯2) In-GaN/GaN quantum wells (QW). By solving the 6 × 6 k·p Hamiltonian, including strain and polarization fields, we study the separation, ordering, and wavefunction character of the topmost valence bands in the QW and their dependence on In composition and QW width. Our results show that quantum confinement has only slight effects on the ordering and the character of the valence states and therefore cannot be the cause of the experimentally observed optical polarization switching. Instead, the switching may be due to the inhomogeneous strain distribution in (112¯2) InGaN films with high In composition.
Optimal coherent control of coherent anti-Stokes Raman scattering: Signal enhancement and background elimination
Authors: Gao Fang , Shuang Feng , Shi Junhui , Rabitz Herschel , Wang Haifeng , Cheng Ji-Xin
Published: April 2012

The ability to enhance resonant signals and eliminate the non-resonant background is analyzed for coherent anti-Stokes Raman scattering (CARS). The analysis is done at a specific frequency as well as for broadband excitation using femtosecond pulse-shaping techniques. An appropriate objective functional is employed to balance resonant signal enhancement against non-resonant background suppression. Optimal enhancement of the signal and minimization of the background can be achieved by shaping the probe pulse alone while keeping the pump and Stokes pulses unshaped. In some cases analytical forms for the probe pulse can be found, and numerical simulations are carried out for other circumstances. It is found that a good approximate optimal solution for resonant signal enhancement in two-pulse CARS is a superposition of linear and arctangent-type phases for the pump. The well-known probe delay method is shown to be a quasi-optimal scheme for broadband background suppression. The results should provide a basis to improve the performance of CARS spectroscopy and microscopy.
The integration of high-k dielectric on two-dimensional crystals by atomic layer deposition
Authors: Liu Han , Xu Kun , Zhang Xujie , Ye Peide D.
Published: April 2012

We investigate the integration of Al2O3 high-k dielectric on two-dimensional (2D) crystals of boron nitride (BN) and molybdenum disulfide (MoS2) by atomic layer deposition (ALD). We demonstrate the feasibility of direct ALD growth with trimethylaluminum and water as precursors on both 2D crystals. Through theoretical and experimental studies, we found that the initial ALD cycles play the critical role, during which physical adsorption dominates precursor adsorption at the crystal surface. We model the initial ALD growth stages at the 2D surface by analyzing Lennard-Jones potentials, which could guide future optimization of the ALD process on 2D crystals.
Nucleation of metals by strong electric fields
Authors: Nardone M. , Karpov V. G.
Published: April 2012

Recent work on phase transitions in chalcogenides (underlying phase change memory) led to a theory of symmetry-breaking field effects, predicting needle-shaped metallic nuclei and exponentially accelerated nucleation rates. Here, we predict that, in general, any insulator will eventually form metallic inclusions if immersed in a sufficient electric field. These phase transitions are driven, not simply enhanced, by an electric field. Hence, metals can be formed under conditions where they would be otherwise unexpected. This opens the venue of field induced materials synthesis. As a technologically important example, we consider the field driven synthesis of metallic hydrogen at normal pressure.
Application of ring method to measure surface tensions of liquids in high magnetic field
Authors: Li Chuanjun , Chen Long , Ren Zhongming
Published: April 2012

The high-magnetic-field tensiometer (HMFT) has been developed to measure surface tensions of liquids in high magnetic field based on the ring method. The HMFT was composed of three parts: weighing system, liquid circulatory system, and supporting system. Some improvements for the conventional tensiometer were made in order to overcome the magnetic effects. The surface tension of acetone was measured using the HMFT. The results showed that the surface tension of acetone linearly varied with the magnetic field intensity and increased by 0.69 mN m−1 or 2.9% in the magnetic field of 10 T. The HMFT could better determine the surface tension of liquids with and without the magnetic field and it provided a simple and practical way to measure the surface tension of liquids at room temperature in a high magnetic field.
Hydrodynamic loading and viscous damping of patterned perforations on microfabricated resonant structures
Authors: Park Kidong , Shim Jiwook , Solovyeva Vita , Corbin Elise , Banerjee Shouvik , Bashir Rashid
Published: April 2012

We examined the hydrodynamic loading of vertically resonating microfabricated plates immersed in liquids with different viscosities. The planar structures were patterned with focused ion beam, perforating various shapes with identical area but varying perimeters. The hydrodynamic loading of various geometries was characterized from resonant frequency and quality factor. In water, the damping increased linearly with the perimeter at 45.4 × 10−3 Ns/m2, until the perforation’s radius was 123% ± 13% of the depth of penetration of fluid’s oscillation. The added mass effect decreased with perforations and recovered to the level of un-perforated structures when the perforation’s radius became smaller than the depth of penetration.
Giant reversible magnetocaloric effect in ErMn2Si2 compound with a second order magnetic phase transition
Authors: Li Lingwei , Nishimura Katsuhiko , Hutchison Wayne D. , Qian Zhenghong , Huo Dexuan , NamiKi Takahiro
Published: April 2012

The magnetic properties and magnetocaloric effect (MCE) in the ternary intermetallic compound ErMn2Si2 have been studied by magnetization and heat capacity measurements. A giant reversible MCE has been observed, accompanied by a second order magnetic phase transition from paramagnetic to ferromagnetic at ∼4.5 K. Under a field change of 5 T, the maximum value of magnetic entropy change (−ΔSMmax) is 25.2 J kg−1 K−1 with no thermal and field hysteresis loss, and the corresponding maximum value of adiabatic temperature change (ΔTadmax) is 12.9 K. Particularly, the values of −ΔSMmax and ΔTadmax reached 20.0 J kg−1 K−1 and 5.4 K for a low field change of 2 T, respectively. The present results indicate that the ErMn2Si2 compound is an attractive candidate for low temperature magnetic refrigeration.
High-performance microfluidic rectifier based on sudden expansion channel with embedded block structure
Authors: Tsai Chien-Hsiung , Lin Che-Hsin , Fu Lung-Ming , Chen Hui-Chun
Published: April 2012

A high-performance microfluidic rectifier incorporating a microchannel and a sudden expansion channel is proposed. In the proposed device, a block structure embedded within the expansion channel is used to induce two vortex structures at the end of the microchannel under reverse flow conditions. The vortices reduce the hydraulic diameter of the microchannel and, therefore, increase the flow resistance. The rectification performance of the proposed device is evaluated by both experimentally and numerically. The experimental and numerical values of the rectification performance index (i.e., the diodicity, Di) are found to be 1.54 and 1.76, respectively. Significantly, flow rectification is achieved without the need for moving parts. Thus, the proposed device is ideally suited to the high pressure environment characteristic of most micro-electro-mechanical-systems (MEMS)-based devices. Moreover, the rectification performance of the proposed device is superior to that of existing valveless rectifiers based on Tesla valves, simple nozzle/diffuser structures, or cascaded nozzle/diffuser structures.
Covalently immobilized biomolecule gradient on hydrogel surface using a gradient generating microfluidic device for a quantitative mesenchymal stem cell study
Authors: Liu Zongbin , Xiao Lidan , Xu Baojian , Zhang Yu , Mak Arthur FT , Li Yi , Man Wing-yin , Yang Mo
Published: April 2012

Precisely controlling the spatial distribution of biomolecules on biomaterial surface is important for directing cellular activities in the controlled cell microenvironment. This paper describes a polydimethylsiloxane (PDMS) gradient-generating microfluidic device to immobilize the gradient of cellular adhesive Arg-Gly-Asp (RGD) peptide on poly (ethylene glycol) (PEG) hydrogel. Hydrogels are formed by exposing the mixture of PEG diacrylate (PEGDA), acryloyl-PEG-RGD, and photo-initiator with ultraviolet light. The microfluidic chip was simulated by a fluid dynamic model for the biomolecule diffusion process and gradient generation. PEG hydrogel covalently immobilized with RGD peptide gradient was fabricated in this microfluidic device by photo-polymerization. Bone marrow derived rat mesenchymal stem cells (MSCs) were then cultured on the surface of RGD gradient PEG hydrogel. Cell adhesion of rat MSCs on PEG hydrogel with various RGD gradients were then qualitatively and quantitatively analyzed by immunostaining method. MSCs cultured on PEG hydrogel surface with RGD gradient showed a grated fashion for cell adhesion and spreading that was proportional to RGD concentration. It was also found that 0.107–0.143 mM was the critical RGD concentration range for MSCs maximum adhesion on PEG hydrogel.
Membrane metamaterial resonators with a sharp resonance: A comprehensive study towards practical terahertz filters and sensors
Authors: Chen Yongyao , Al-Naib Ibraheem A. I. , Gu Jianqiang , Wang Mingwei , Ozaki Tsuneyuki , Morandotti Roberto , Zhang Weili
Published: April 2012

We investigate the resonant properties of high quality-factor membrane-based metamaterial resonators functioning in the terahertz regime. A number of factors, including the resonator geometry, dielectric loss, and most importantly the membrane thickness are found to extensively influence the resonance strength and quality factor of the sharp resonance. Further studies on the membrane thickness-dependent-sensitivity for sensing applications reveal that high quality-factor membrane metamaterials with a moderate thickness ranging from 10 to 50 μm are the most promising option towards developing realistic integrated terahertz filters and sensors.
Salience Theory of Choice Under Risk
Authors: Bordalo Pedro , Gennaioli Nicola , Shleifer Andrei
Published: April 2012

We present a theory of choice among lotteries in which the decision maker's attention is drawn to (precisely defined) salient payoffs. This leads the decision maker to a context-dependent representation of lotteries in which true probabilities are replaced by decision weights distorted in favor of salient payoffs. By specifying decision weights as a function of payoffs, our model provides a novel and unified account of many empirical phenomena, including frequent risk-seeking behavior, invariance failures such as the Allais paradox, and preference reversals. It also yields new predictions, including some that distinguish it from prospect theory, which we test.
Sphingomonas ginsengisoli sp. nov. and Sphingomonas sediminicola sp. nov.
Authors: An Dong-Shan , Liu Qing-Mei , Lee Hyung-Gwan , Jung Mi-Seon , Kim Sun-Chan , Lee Sung-Taik , Im Wan-Taek
Published: April 2012

Two novel bacteria, designated strains Gsoil 634T and Dae 20T, were isolated in South Korea from soil of a ginseng field and freshwater sediment, respectively and were characterized by a polyphasic approach to clarify their taxonomic positions. Phylogenetic analysis based on 16S rRNA gene sequences indicated that, although they probably represented two distinct species (indicated by a sequence similarity of 96.6 %), both strain Gsoil 634T and strain Dae 20T belonged to the genus

Sphingomonas

and were most closely related to ‘Sphingomonas humi’ PB323 (97.8 % and 96.7 % sequence similarity, respectively),

Sphingomonas kaistensis

PB56T (96.8 % and 96.7 %),

Sphingomonas astaxanthinifaciens

TDMA-17T (96.6 % and 95.4 %) and

Sphingomonas jaspsi

TDMA-16T (95.6 % and 95.8 %). For both novel strains, the major ubiquinone was Q-10, the major polyamine was homospermidine, the major cellular fatty acids included summed feature 7 (C18 : 1ω7c, C18 : 1ω9t and/or C18 : 1ω12t), C17 : 1ω6c and C16 : 0, and the polar lipids included sphingoglycolipid. These chemotaxonomic data supported the affiliation of both strains to the genus

Sphingomonas

. However, the DNA–DNA relatedness value between strain Gsoil 634T and ‘Sphingomonas humi’ PB323T was 31 %. Moreover, the results of physiological and biochemical tests allowed the phenotypic differentiation of strains Gsoil 634T and Dae 20T from established members of the genus

Sphingomonas

. Based on these data, the two isolates represent two novel species in the genus

Sphingomonas

, for which the names Sphingomonas ginsengisoli sp. nov. (type strain Gsoil 634T = KCTC 12630T = DSM 18094T = LMG 23739T) and Sphingomonas sediminicola sp. nov. (type strain Dae 20T  = KCTC 12629T = DSM 18106T = LMG 23592T) are proposed.
Drosophila Neto is essential for clustering glutamate receptors at the neuromuscular junction
Authors: Kim Young-Jun , Bao Hong , Bonanno Liana , Zhang Bing , Serpe Mihaela
Published: April 2012

Neurotransmitter receptor recruitment at postsynaptic specializations is key in synaptogenesis, since this step confers functionality to the nascent synapse. The Drosophila neuromuscular junction (NMJ) is a glutamatergic synapse, similar in composition and function to mammalian central synapses. Various mechanisms regulating the extent of postsynaptic ionotropic glutamate receptor (iGluR) clustering have been described, but none are known to be essential for the initial localization and clustering of iGluRs at postsynaptic densities (PSDs). We identified and characterized the Drosophila neto (neuropilin and tolloid-like) as an essential gene required for clustering of iGluRs at the NMJ. Neto colocalizes with the iGluRs at the PSDs in puncta juxtaposing the active zones. neto loss-of-function phenotypes parallel the loss-of-function defects described for iGluRs. The defects in neto mutants are effectively rescued by muscle-specific expression of neto transgenes. Neto clustering at the Drosophila NMJ coincides with and is dependent on iGluRs. Our studies reveal that Drosophila Neto is a novel, essential component of the iGluR complexes and is required for iGluR clustering, organization of PSDs, and synapse functionality.
HOT regions function as patterned developmental enhancers and have a distinct cis-regulatory signature
Authors: Kvon Evgeny Z. , Stampfel Gerald , Yáñez-Cuna J. Omar , Dickson Barry J. , Stark Alexander
Published: April 2012

HOT (highly occupied target) regions bound by many transcription factors are considered to be one of the most intriguing findings of the recent modENCODE reports, yet their functions have remained unclear. We tested 108 Drosophila melanogaster HOT regions in transgenic embryos with site-specifically integrated transcriptional reporters. In contrast to prior expectations, we found 102 (94%) to be active enhancers during embryogenesis and to display diverse spatial and temporal patterns, reminiscent of expression patterns for important developmental genes. Remarkably, HOT regions strongly activate nearby genes and are required for endogenous gene expression, as we show using bacterial artificial chromosome (BAC) transgenesis. HOT enhancers have a distinct cis-regulatory signature with enriched sequence motifs for the global activators Vielfaltig, also known as Zelda, and Trithorax-like, also known as GAGA. This signature allows the prediction of HOT versus control regions from the DNA sequence alone.
Polycomb function during oogenesis is required for mouse embryonic development
Authors: Posfai Eszter , Kunzmann Rico , Brochard Vincent , Salvaing Juliette , Cabuy Erik , Roloff Tim C. , Liu Zichuan , Tardat Mathieu , van Lohuizen Maarten , Vidal Miguel , Beaujean Nathalie , Peters Antoine H.F.M.
Published: April 2012

In mammals, totipotent embryos are formed by fusion of highly differentiated gametes. Acquisition of totipotency concurs with chromatin remodeling of parental genomes, changes in the maternal transcriptome and proteome, and zygotic genome activation (ZGA). The inefficiency of reprogramming somatic nuclei in reproductive cloning suggests that intergenerational inheritance of germline chromatin contributes to developmental proficiency after natural conception. Here we show that Ring1 and Rnf2, components of Polycomb-repressive complex 1 (PRC1), serve redundant transcriptional functions during oogenesis that are essential for proper ZGA, replication and cell cycle progression in early embryos, and development beyond the two-cell stage. Exchange of chromosomes between control and Ring1/Rnf2-deficient metaphase II oocytes reveal cytoplasmic and chromosome-based contributions by PRC1 to embryonic development. Our results strongly support a model in which Polycomb acts in the female germline to establish developmental competence for the following generation by silencing differentiation-inducing genes and defining appropriate chromatin states.
Genome sequencing reveals complex speciation in the Drosophila simulans clade
Authors: Garrigan Daniel , Kingan Sarah B. , Geneva Anthony J. , Andolfatto Peter , Clark Andrew G. , Thornton Kevin R. , Presgraves Daven C.
Published: April 2012

The three species of the Drosophila simulans clade—the cosmopolitan species, D. simulans, and the two island endemic species, D. mauritiana and D. sechellia—are important models in speciation genetics, but some details of their phylogenetic and speciation history remain unresolved. The order and timing of speciation are disputed, and the existence, magnitude, and timing of gene flow among the three species remain unclear. Here we report on the analysis of a whole-genome four-species sequence alignment that includes all three D. simulans clade species as well as the D. melanogaster reference sequence. The alignment comprises novel, paired short-read sequence data from a single highly inbred line each from D. simulans, D. mauritiana, and D. sechellia. We are unable to reject a species phylogeny with a basal polytomy; the estimated age of the polytomy is 242,000 yr before the present. However, we also find that up to 4.6% of autosomal and 2.2% of X-linked regions have evolutionary histories consistent with recent gene flow between the mainland species (D. simulans) and the two island endemic species (D. mauritiana and D. sechellia). Our findings thus show that gene flow has occurred throughout the genomes of the D. simulans clade species despite considerable geographic, ecological, and intrinsic reproductive isolation. Last, our analysis of lineage-specific changes confirms that the D. sechellia genome has experienced a significant excess of slightly deleterious changes and a dearth of presumed favorable changes. The relatively reduced efficacy of natural selection in D. sechellia is consistent with its derived, persistently reduced historical effective population size.
Genome-wide analysis of mutations in mutant lineages selected following fast-neutron irradiation mutagenesis of Arabidopsis thaliana
Authors: Belfield Eric J. , Gan Xiangchao , Mithani Aziz , Brown Carly , Jiang Caifu , Franklin Keara , Alvey Elizabeth , Wibowo Anjar , Jung Marko , Bailey Kit , Kalwani Sharan , Ragoussis Jiannis , Mott Richard , Harberd Nicholas P.
Published: April 2012

Ionizing radiation has long been known to induce heritable mutagenic change in DNA sequence. However, the genome-wide effect of radiation is not well understood. Here we report the molecular properties and frequency of mutations in phenotypically selected mutant lines isolated following exposure of the genetic model flowering plant Arabidopsis thaliana to fast neutrons (FNs). Previous studies suggested that FNs predominantly induce deletions longer than a kilobase in A. thaliana. However, we found a higher frequency of single base substitution than deletion mutations. While the overall frequency and molecular spectrum of fast-neutron (FN)–induced single base substitutions differed substantially from those of “background” mutations arising spontaneously in laboratory-grown plants, G:C>A:T transitions were favored in both. We found that FN-induced G:C>A:T transitions were concentrated at pyrimidine dinucleotide sites, suggesting that FNs promote the formation of mutational covalent linkages between adjacent pyrimidine residues. In addition, we found that FNs induced more single base than large deletions, and that these single base deletions were possibly caused by replication slippage. Our observations provide an initial picture of the genome-wide molecular profile of mutations induced in A. thaliana by FN irradiation and are particularly informative of the nature and extent of genome-wide mutation in lines selected on the basis of mutant phenotypes from FN-mutagenized A. thaliana populations.
Serotonin transporter knockout rats show improved strategy set-shifting and reduced latent inhibition
Authors: Nonkes Lourens J.P. , van de Vondervoort Ilse I.G.M. , de Leeuw Mark J.C. , Wijlaars Linda P. , Maes Joseph H.R. , Homberg Judith R.
Published: April 2012

Behavioral flexibility is a cognitive process depending on prefrontal areas allowing adaptive responses to environmental changes. Serotonin transporter knockout (5-HTT−/−) rodents show improved reversal learning in addition to orbitofrontal cortex changes. Another form of behavioral flexibility, extradimensional strategy set-shifting (EDSS), heavily depends on the medial prefrontal cortex. This region shows functional changes in 5-HTT−/− rodents as well. Here we subjected 5-HTT−/− rats and their wild-type counterparts to an EDSS paradigm and a supplementary latent inhibition task. Results indicate that 5-HTT−/− rats also show improved EDSS, and indicate that reduced latent inhibition may contribute as an underlying mechanism.
DNA Millichips as a Low-Cost Platform for Gene Expression Analysis
Authors: Heinrich Kurt W. , Wolfer Jamison , Hong DongGee , LeBlanc Melissa , Sussman Michael R.
Published: April 2012

Our goal was to create a DNA chip that is as easy, convenient, and inexpensive as an agarose gel. For a first-generation solution, we describe a low-cost, easy-to-use de novo synthesis oligonucleotide microarray technology that draws on the inherent flexibility of the maskless array synthesizer for in situ synthesis of thousands of photolithographically produced oligonucleotides covalently attached to a microscope slide. The method involves physically subdividing the slide into 1 × 1 mm millichips that are hybridized to fluorescent RNA or DNA of biological origin, in a microfuge tube at an ordinary laboratory benchtop, rather than in dedicated hybridization chambers. Fluorescence intensity is then measured with a standard microscope rather than sophisticated DNA chip scanners. For proof of principle, we measured changes in the transcriptome of Arabidopsis (Arabidopsis thaliana) plants induced by growth in the presence of three major environmental abiotic stresses (temperature, light, and water status), in all possible combinations. Validation by comparison with quantitative reverse transcription PCR showed a high correlation coefficient and analysis of variance indicated a high technical reproducibility. These experiments demonstrate that low-cost DNA millichips can be made and reliably used at the benchtop in a normal laboratory setting, without assistance of core facilities containing costly specialized instrumentation.
Removing the boardroom glass ceiling
Authors: Hurn Brian J.
Published: April 2012

Purpose

This paper aims to review progress to date in the UK on Government strategy to increase the number of women on company boards. It includes discussion on the proposed quota system and the factors that inhibit women's progress despite the acknowledged special qualities they can bring to the boardroom.

Design/methodology/approach

The paper is a critical review of the current situation in the UK and rest of Europe, leading to recommendations for the way ahead.

Findings

Corporate culture in top companies is gradually changing and some, albeit slow, progress has been made. However more impetus is required and suggestions are included as to future additional strategies.

Practical implications

Additional suggestions, apart from the Government strategy, are given to improve women's career development in companies, in the educational system and in society in general.

Originality/value

The paper puts forward practical suggestions to assist women's career development and visibility to enable more qualified and experienced women to be strong candidates for board appointments.
A framework for auditing HR: strengthening the role of HR in the organisation
Authors: Cannings Anne , Hills Trevor
Published: April 2012

Purpose

This paper aims to propose that a new approach to human resource (HR) audit is needed. It also aims to explain the new approach and introduce a range of tools to support it.

Design/methodology/approach

The paper reviews traditional and existing common approaches, identifies the shortcomings of these, and proposes a new framework based on business contribution.

Findings

Existing approaches to HR audit do not reflect the current aspirations and rhetoric on HR practices as promoted by Holbeche, and Ulrich et al.This emphasises the need for a new approach.

Practical implications

The work proposes a new framework to assess HR activity against alignment and contribution to organisation strategy and goals, as well as the prevailing culture, thus forcing HR audit to move beyond legal compliance of HR practices. A range of processes, tools and techniques are identified.

Originality/value

The paper contains a completely new approach (the authors assert) to HR audit which is more rigorous and wide ranging in scope. It moves HR audit away from legal compliance to increasing the HR contribution to the organisation, thereby creating improved business performance.
Impact of oleoyl glycine on biodegradability and lubricity of lubricating oil
Authors: Chen Boshui , Huang Weijiu , Fang Jianhua
Published: April 2012

Purpose

The purpose of this paper is to understand the impacts of oleoyl glycine on biodegradation, friction and wear performances of a mineral lubricating oil.

Design/methodology/approach

The biodegradabilities of a neat oil and its formulations with oleoyl glycine were evaluated on a biodegradation tester and the microbial characters in the biodegradation sewage observed through a microscope. Also, the friction and wear performances of neat oil and the formulated oil were determined on a four‐ball tribometer. The morphologies and tribochemical features of the worn surfaces were analyzed by scanning electron microscopy and X‐ray photoelectron spectroscopy.

Findings

Oleoyl glycine markedly enhanced biodegradation of unreadily biodegradable mineral oil and effectively improved its anti‐wear and friction‐reducing abilities. The enhancement of biodegradability of the mineral oil was preliminarily ascribed to the increment of microbial populations in the biodegradation processes, while the improvement of anti‐wear and friction‐reducing abilities was mainly attributed to the formation of a boundary adsorption film of oleoyl glycine on the friction surfaces.

Originality/value

Oleoyl glycine is a biodegradable and low eco‐toxic compound. The authors' work has shown that oleoyl glycine is effective in improving biodegradability and tribological performances of mineral lubricants. Enhancing biodegradability of petroleum‐based lubricants by additives is a new attempt. The paper has significance for improving ecological and tribological performances of mineral lubricants, even for developing petroleum‐based biodegradable lubricants.
Non‐destructive subsurface damage monitoring in bearings failure mode using fractal dimension analysis
Authors: Holweger Walter , Walther Frank , Loos Jörg , Wolf Marcus , Schreiber Jürgen , Dreher Werner , Kern Norbert , Lutz Steffen
Published: April 2012

Purpose

Bearings in field applications with high dynamic loading, e.g. wind energy plants, suffer from sudden failure initiated by subsurface material transformation, known as white etching cracks in a typical scale of μm, preferably around the maximum Hertzian stress zone. Despite many investigations in this field no precise knowledge about the root cause of those failures is available, due to the fact that failure under real service conditions of wind energy plants differs from what is known from test rig results in terms of contact loading, lubrication or dynamics. The purpose of this paper is to apply Barkhausen noise measurement to a full bearing test ring running under conditions of elastohydrodynamic lubrication (EHL) with high radial preload.

Design/methodology/approach

Full bearing tests are carried out by use of DGBB (Deep Grove Ball Bearings) with 6206 specification, material set constant as 100Cr6, martensitic hardening, 10‐12 percent maximum retained austenite and radial preload of 3500 MPa. Speed is set 9000 rpm, temperature is self setting at 80°C by test conditions. For tests, synthetic hydrocarbon base oil (Poly‐α‐Olefine) with a 1 percent amount of molydenum‐dithiophosphate (organic chain given as 2‐ethylhexyl) was used.

Findings

Non‐destructive fractal dimension analyses by use of Barkhausen noise measurements is of versatile value in terms of recording bearing manufacturing processes, but can also be part of non‐destructive condition monitoring of bearings in field applications, where predictive reactive maintenance is crucial for availability of the plant.

Research limitations/implications

Barkhausen noise signal recording may also be valuable for case studies related to microstructure changes of steel under operation conditions. Bearings are exposed in plenty of conditions to phenomena such as straying currents, subsequently straying magnetic fields. Hardly anything is known about how microstructure of bearing steel is susceptible to such conditions. This will be part of further studies.

Originality/value

Results given in the paper show that sudden bearing failure, according to formation of subsurface material property changes might be driven by activities of dislocations. Since those activities start with sequences of stress field‐induced formation of domains, later by formation of low‐angle subgrains, and at least phase transformation, recording of the Barkhausen signal would lead to real predictive condition monitoring in applications where a highly dynamic loading of the contact, even with low nominal contact pressure leads to sudden failure induced by white etching.
Investigation of friction and wear behavior of hybrid aluminium composites
Authors: Velmurugan C. , Subramanian R. , Thirugnanam S. , Anandavel B.
Published: April 2012

Purpose

The purpose of this technical paper is to investigate the friction and wear behaviour of heat treated Al 6061 alloy and Al 6061 SiC‐graphite particulate reinforced hybrid composites subjected to different ageing durations.

Design/methodology/approach

The composites have been prepared by stir casting process with varying percentages of SiC and graphite particles. The cast 6061 alloy and its composites were subjected to solutionising treatment at a temperature of 803 K for 1 hr followed by quenching in water. The quenched samples were then subjected to artificial ageing for different durations of 4, 6, 8 hr at a temperature of 448 K. Tests were performed on heat treated Al 6061 alloy and its composites using pin‐on‐disc apparatus. Hardness measurements were also made on the specimens. The wear surfaces of the composites were analyzed using scanning electron microscopy.

Findings

During wear test of specimens the wear resistance of the hybrid composites was found to increase with increase in ageing durations. The microscopic examination of the wear surfaces shows that the base alloy and composites wear primarily because of abrasion and delamination. The hardness result shows that the hardness of the composites increased with decreasing weight percentage of graphite particles.

Originality/value

The content of this paper is fully research oriented and the finding from this investigation will be useful for society and also the automobile industries, especially in the making of brake drums.
Tribological properties of nylon 1010 composites filled with zinc oxide whisker in rolling friction with traction
Authors: Shi‐bo Wang
Published: April 2012

Purpose

The purpose of this paper is to improve the tribological properties of Polyamide 1010 (PA 1010) in rolling friction with traction.

Design/methodology/approach

PA1010 composites filled with zinc oxide whiskers (ZnOw) were prepared by hot compression molding. The compressive properties of the composites were measured with an electronic material tester and the tribological behavior in rolling friction with traction of nylon composites was studied with a two‐roller contact rolling tester.

Findings

The results indicate that the compression modulus of composites increases with the rising content of ZnOw. Both the ultimate compression strength and the compression yield strength of composites increase to the maximum value when the content of ZnOw is 15 wt%. Both the traction coefficient and the slip ratio of each composite were influenced by the traction load and the normal load. In addition, the ZnOw proportion affected the slip ratio of the composites. The experimental results demonstrate that composites including 10 wt% and 15 wt% ZnOw exhibit lighter wear and lower slip ratio. The wear rate of the nylon composites is increased as the normal load increases due to the rising acting pressure against the nylon composites. The rising traction load also causes inflation in the wear rate of the composites.

Research limitations/implications

The tests in the paper were carried out according to the conditions of tramcars in mining.

Practical implications

PA 1010 composites filled with ZnOw presented the preferable mechanical and tribological properties of PA1010, which can be used in the driving wheel of tramcars in mining and other components requiring high traction coefficient.

Originality/value

The paper studied the tribological properties of PA 1010 composites including ZnOw with special dimensional structure.
Performance of a noncircular 2‐lobe multirecess hydrostatic journal bearing with wear
Authors: Sharma Satish C. , Phalle Vikas M. , Jain S.C.
Published: April 2012

Purpose

Noncircular journal bearings are used in industry because of their simplicity, efficiency and low cost. During the life time of a machine, these are required to be operated over a number of years and are submitted to several stops and starts. As a result, the bush becomes progressively worn out and the bearing performance changes. The purpose of this paper is to study theoretically the influence of wear on the performance of a non‐circular 2‐lobe four‐pocket multirecess hybrid journal bearing system.

Design/methodology/approach

The Reynolds equation governing the flow of lubricant in the clearance space of a non‐circular 2‐lobe multirecess worn hybrid journal bearing system has been solved using FEM along with appropriate boundary conditions. The defects caused by wear are centered on the load line and range from 10 per cent to 50 per cent of the bearing radial clearance.

Findings

The numerically simulated results based on a Newtonian lubricant and the steady state flow field system have been presented in terms of maximum fluid film pressure, minimum fluid film thickness, lubricant flow rate, direct fluid film stiffness and damping coefficients and stability threshold speed margin. The paper demonstrates that, for the bearing configurations studied, the bearing behavior is clearly affected by wear. The numerically simulated results indicate that for an offset factor of δ=1.2, the value of h¯min reduces by 21.21 per cent at δ¯w=0.5.

Originality/value

The presented results have valuable data in case of 2‐lobe four pocket hybrid journal bearing compensated with constant flow valve restrictor. The paper outcomes are sure to be of interest for researchers and useful for bearing designers.
Female directors and earnings management in high‐technology firms
Authors: Gavious Ilanit , Segev Einav , Yosef Rami
Published: April 2012

Purpose

This study, based on a merger of gender and accounting theories, aims to explore whether and how earnings management is affected by the presence of female directors on the board of directors and on the audit committee.

Design/methodology/approach

The study employs both a univariate and multivariate analysis approach to explore the relation between female directors and earnings management in high‐technology firms. In the analysis, two contemporary ex‐post measures of earnings management, discretionary accruals and nonoperating accruals, as well as two ex‐ante measures of earnings management, Big4 auditor and financial leverage are applied.

Findings

The paper finds evidence for a negative relation between the presence of female directors and earnings management. The findings indicate that accounting aggressiveness is affected by the proportion of women on the board of directors as well as on the audit committee. Furthermore, the paper find evidences indicating that earnings management is lower when either the CEO or the CFO is a woman. Notably, in firms with a higher female representation in corporate governance and/or in top management, external monitoring by auditors and creditors seems to be weaker, yet earnings quality is higher. Additional analysis suggests that the gender of directors has value implications for analysts and investors; specifically, there is a positive relation between the proportion of female directors and the firm's value. The findings are supported by several gender theories and findings regarding women's motivation and achievement, moral values, social stereotypes and the relation between task performance and self‐confidence.

Originality/value

This study associates the gender of directors with earnings management by firms. The study contributes to the growing body of literature on earnings management. It should be useful to researchers, regulators, investors, analysts and creditors as well as other players in the capital markets, as it presents a new and important aspect that needs to be accounted for when assessing the quality of firms' accounting information.
Success in winning Australian Research Council grants as a measure of comparative professionalised disciplinary research activity
Authors: Clarke Kevin , Flanagan Jack , O'Neill Sharron
Published: April 2012

Purpose

The purpose of this paper is to analyse the performance of accounting researchers in winning competitive Australian Research Council (ARC) grants, when compared with researchers from the medical, engineering and law professions, during a period of heightened questioning of accounting methods, bounded by the end of the dot.com boom in 2001 and the global financial crisis in 2008. Protection and expansion of a profession's core knowledge through effective research is regarded as a hallmark of ongoing professional recognition and success in winning ARC grants is one indicator of the strength of this research. Reasons for the absolute and relative performance of accounting researchers in winning ARC grants are explored.

Design/methodology/approach

ARC statistics for the 2000‐2008 period were analysed, along with additional data from the relevant professional associations and the Commonwealth Department of Education, Employment and Workplace Relations.

Findings

The results indicate that Australian accounting researchers are performing poorly in absolute and relative terms when compared with their professional peers. Some evidence exists that accounting research cultures seem to flourish in only a handful of universities, and that accounting academics are overloaded with teaching to the detriment of research.

Originality/value

The study adds to the growing interest in the value added by accounting research to the accounting profession, the corporate sector and society at large. While the publishing record of Australian accounting researchers appears healthy, when compared with their accounting peers overseas, they perform poorly in winning competitive grants relative to researchers from other professions. This may be a timely wakeup call to the accounting profession that the social acceptance of accounting knowledge should not be taken for granted.