bluuebunny/crossref_metadata_2025 huggingface dataset:
The evolution of the nuclear receptor superfamily
Authors: Escriva Héctor , Bertrand Stéphanie , Laudet Vincent
Published: August 2015

Nuclear receptors form a superfamily of ligand-activated transcription factors implicated in various physiological functions from development to homoeostasis. Nuclear receptors share a common evolutionary history revealed by their conserved structure and by their high degree of sequence conservation. Here we review the latest advances on the evolution of nuclear receptors by addressing the following questions. What is known about the appearance and diversification of nuclear hormone receptors? How did their different functional characteristics evolve? What can we infer from the analysis of complete genomes? In summary, the study of the evolution of nuclear receptors will be very important not only for understanding their functions in vivo but also for obtaining insights into the evolution of animal genomes as a whole.
Ubiquitin-binding proteins: similar, but different
Authors: Andersen Katrine M. , Hofmann Kay , Hartmann-Petersen Rasmus
Published: August 2015

Covalent modification of proteins with ubiquitin is a common regulatory mechanism in eukaryotic cells. Typically, ubiquitinated proteins are targeted for degradation by the 26 S proteasome. However, more recently the ubiquitin signal has also been connected with many other cell processes, including endocytosis, vesicle fusion, DNA repair and transcriptional silencing. Hence ubiquitination may be comparable with phosphorylation in its importance as an intracellular switch, controlling various signal-transduction pathways. Similar to the regulation of the extent of phosphorylation by kinases and phosphatases, specific sets of ubiquitinating/deubiquitinating enzymes control the degree of ubiquitination. A large number of ubiquitin-binding proteins act at different steps in the downstream pathways, followed by the ubiquitinated protein. Different families of ubiquitin-binding proteins have been described. UBA (ubiquitin-associated) domain-containing proteins is the largest family and includes members involved in different cell processes. The smaller groups of UIM (ubiquitin-interacting motif), GAT [GGA (Golgi-associated γ-adaptin homologous) and Tom1 (target of Myb 1)], CUE (coupling of ubiquitin conjugation to endoplasmic reticulum degradation), UEV [ubiquitin E2 (ubiquitin-conjugating enzyme) variant] and NZF (nuclear protein localization gene 4 zinc finger) domain-containing proteins appear to have more specialized functions. Here we discuss functional and structural properties of ubiquitin-binding proteins.
Ubiquitin and endocytic protein sorting
Authors: Urbé Sylvie
Published: August 2015

Ubiquitin plays a fundamental role not only in proteasome-mediated protein degradation but also in the targeting of membrane proteins for degradation inside the lysosome. Ubiquitination provides a key signal for endosomal sorting of membrane proteins into the MVB (multi-vesicular body), which delivers its cargo to the proteolytic interior of the lysosome. Attachment of single ubiquitin molecules, rather than ubiquitin chains, to one or multiple lysines of the cytoplasmic domains of many growth factor receptors, ion channels and other membrane transporters is sufficient to target these proteins to a complex sorting apparatus on the endosome. This machinery selects ubiquitinated proteins for lysosomal sorting through consecutive interactions with a variety of ubiquitin-binding domains. The major ubiquitin ligase (E3) responsible for ubiquitination in this pathway in yeast is the HECT [homologous to E6-AP (E6-associated protein) C-terminus]-ligase, Rsp5, whereas in mammalian cells the RING (really interesting new gene)-ligase Cbl has been implicated in the down-regulation of several RTKs (receptor tyrosine kinases). Ubiquitinated receptors can be rescued from degradation by the activity of DUBs (deubiquitinating enzymes), which may provide a proofreading mechanism that enhances the fidelity of this sorting and degradation process. DUBs also allow for recycling of the ubiquitin moieties from proteins prior to their final commitment to the MVB and lysosome interior.
The ubiquitin–proteasome system and neurodegenerative disorders
Authors: Layfield Robert , Lowe James , Bedford Lynn
Published: August 2015

As in all other mammalian tissues, the UPS (ubiquitin–proteasome system) is fundamental to normal brain function. A consistent feature of the major human neurodegenerative disorders is the accumulation of disease-related proteins, in non-native conformations, as protein aggregates within neurons or glial cells. Often the proteins in these aggregates are post-translationally conjugated with ubiquitin, suggesting a possible link between pathological protein-aggregation events in the nervous system and dysfunction of the UPS. Genetic evidence clearly demonstrates that disruption of ubiquitin-mediated processes can lead to neurodegeneration; however, the relationship between the UPS and idiopathic neurodegenerative disorders is less clear. In the latter cases, although a number of different mechanisms could potentially contribute to dysfunction of the UPS and promote the neurodegenerative process, whether UPS dysfunction is causally related to disease pathogenesis, or alternatively arises as a result of the pathological state, and indeed whether ubiquitinated inclusions are harmful or beneficial to cells, remains to be clarified.
Therapeutic iron chelators and their potential side-effects
Authors: Singh S. , Khodr Hh , Taylor M. I. , Hider R. C.
Published: August 2015

A number of iron-chelating agents are currently being considered as orally active alternatives to desferrioxamine (DFO), the therapeutic agent for the treatment of body iron overload that is available at present. These include bidentate hydroxypyridinones (HPO), tridentate desferrithiocin (DFT) analogues and hexadentate aminocarboxylate (HBED) chelators. All chelating agents have the potential to induce toxic effects when iron homoeostasis is affected within the body. This can arise when the absorption, distribution and utilization of iron is affected. Alternatively, chelating agents can induce toxicity by directly interfering with iron-dependent metalloenzymes located within the body. These effects are, however, mainly localized to non-haem enzymes such as ribonucleotide reductase and lipoxygenase. The resultant iron complexes also have the ability to induce toxicity. Depending on the coordination geometry and donor atoms associated with the metal centre, redox cycling of the iron centre with the corresponding generation of free radicals can result.
Perturbed endoplasmic reticulum function, synaptic apoptosis and the pathogenesis of Alzheimer's disease
Authors: Mattson Mark P. , Gary Devin S. , Chan Sic L. , Duan Wenzhen
Published: August 2015

Endoplasmic reticulum (ER) appears to be a focal point for alterations that result in neuronal dysfunction and death in Alzheimer's disease (AD). Aberrant proteolytic processing and/or trafficking of the ϐ-amyloid precursor protein (APP) in ER may promote neuronal degeneration by increasing the levels of the neurotoxic forms of ϐ-amyloid (Aϐ) and by decreasing the levels of the neuroprotective secreted form of APP (sAPPα). Some cases of AD are caused by mutations in the genes encoding presenilin 1 (PS1). When expressed in cultured neuronal cells and transgenic mice, PS1 mutations cause abnormalities in ER calcium homoeostasis, enhancing the calcium responses to stimuli that activate IP3- and ryanodine-sensitive ER calcium pools. Two major consequences of this disrupted ER calcium regulation are altered proteolytic processing of APP and increased vulnerability of neurons to apoptosis and excitotoxicity. The impact of PS1 mutations and aberrant APP processing is particularly great in synaptic terminals. Perturbed synaptic calcium homoeostasis promotes activation of apoptotic cascades involving production of Par-4 (prostate apoptosis response-4), mitochondrial dysfunction and caspase activation. Aϐ 42 (the 42-amino-acid form of Aϐ) induces membrane lipid peroxidation in synapses and dendrites resulting in impairment of membrane ion-motive ATPases and glucose and glutamate transporters. This disrupts synaptic ion and energy homoeostasis thereby promoting synaptic degeneration. In contrast, sAPPα activates signalling pathways that protect synapses against excitotoxicity and apoptosis. In the more common sporadic forms of AD, the initiating causes of the neurodegenerative cascade are less well defined, but probably involve increased levels of oxidative stress and impaired energy metabolism. Such alterations have been shown to disrupt neuronal calcium homoeostasis in experimental models, and may therefore feed into the same neurodegenerative cascade initiated by mutations in presenilins and APP. Perturbed synaptic ER calcium homoeostasis and consequent alterations in APP processing appear to be pivotal events in both sporadic and familial forms of AD.
Degradation of explosives by nitrate ester reductases
Authors: Williams Richard E. , Rathbone Deborah A. , Moody Peter C. E. , Scrutton Nigel S. , Bruce Neil C.
Published: August 2015

Explosive-contaminated land poses a hazard both to the environment and to human health. Microbial enzymes, either in their native or heterologous hosts, are a powerful and low-cost tool for eliminating this environmental hazard. As many explosives have only been present in the environment for 10 years, and with similar molecules not known in Nature, the origin of enzymes specialized for the breakdown of explosives is of particular interest. Screening of environmental isolates resulted in the discovery of flavoproteins capable of denitrating the explosives pentaerythritol tetranitrate (PETN) and glycerol trinitrate. These nitrate ester reductases are related in sequence and structure to Old Yellow Enzyme from Saccharomyces carlsbergenisis. All the members of this family have α/ϐ barrel structures and FMN as a prosthetic group, and reduce various electrophilic substrates. The nitrate ester reductases are, however, unusual in that they display activity towards the highly recalcitrant, aromatic explosive 2,4,6-trinitrotoluene, via a reductive pathway resulting in nitrogen liberation. We have embarked on a detailed study of the structure and mechanism of PETN reductase from a strain of Enterobacter cloacae. Work is focused currently on relating structure and function within this growing family of enzymes, with a view to engineering novel enzymes exhibiting useful characteristics.
Flavin radicals, conformational sampling and robust design principles in interprotein electron transfer: the trimethylamine dehydrogenase-electron-transferring flavoprotein complex
Authors: Leys David , Basran Jaswir , Talfournier François , Chohan Kamaldeep K. , Munro Andrew W. , Sutcliffe Michael J. , Scrutton Nigel S.
Published: August 2015

TMADH (trimethylamine dehydrogenase) is a complex iron-sulphur flavoprotein that forms a soluble electron-transfer complex with ETF (electron-transferring flavoprotein). The mechanism of electron transfer between TMADH and ETF has been studied using stopped-flow kinetic and mutagenesis methods, and more recently by X-ray crystallography. Potentiometric methods have also been used to identify key residues involved in the stabilization of the flavin radical semiquinone species in ETF. These studies have demonstrated a key role for 'conformational sampling' in the electron-transfer complex, facilitated by two-site contact of ETF with TMADH. Exploration of three-dimensional space in the complex allows the FAD of ETF to find conformations compatible with enhanced electronic coupling with the 4Fe-4S centre of TMADH. This mechanism of electron transfer provides for a more robust and accessible design principle for interprotein electron transfer compared with simpler models that invoke the collision of redox partners followed by electron transfer. The structure of the TMADH-ETF complex confirms the role of key residues in electron transfer and molecular assembly, originally suggested from detailed kinetic studies in wild-type and mutant complexes, and from molecular modelling.
The 'lipid raft' microdomain proteins reggie-1 and reggie-2 (flotillins) are scaffolds for protein interaction and signalling.
Authors: Stuermer Claudia A. O. , Plattner Helmut
Published: August 2015

Reggie-1 and reggie-2 are two evolutionarily highly conserved proteins which are up-regulated in retinal ganglion cells during regeneration of lesioned axons in the goldfish optic nerve. They are located at the cytoplasmic face of the plasma membrane and are considered to be 'lipid raft' constituents due to their insolubility in Triton X-100 and presence in the 'floating fractions'; hence they were independently named flotillins. According to our current view, the reggies subserve functions as protein scaffolds which form microdomains in neurons, lymphocytes and many other cell types across species as distant as flies and humans. These microdomains are of a surprisingly constant size of less than or equal to 0.1 mm in all cell types, whereas the distance between them is variable. The microdomains co-ordinate signal transduction of specific cell-surface proteins and especially of GPI (glycosylphosphatidylinositol)-anchored proteins into the cell, as is demonstrated for PrPc (cellular prion protein) in T-lymphocytes. These cells possess a pre-formed reggie cap scaffold consisting of densely packed reggie microdomains. PrPc is targeted to the lymphocyte reggie cap when activated by antibody cross-linking, and induces a distinct Ca2+ signal. In developing zebrafish, reggies become concentrated in neurons and axon tracts, and their absence, after morpholino antisense RNA-knockdown, results in deformed embryos with reduced brains. Likewise, defects in Drosophila eye morphogenesis occur upon reggie overexpression in mutant flies. The defects observed in the organism, as well as in single cells in culture, indicate a morphogenetic function of the reggies, with emphasis on the nervous system. This complies with their role as scaffolds for the formation of multiprotein complexes involved in signalling across the plasma membrane.
Pleckstrin homology (PH) domains and phosphoinositides
Authors: Lemmon Mark A.
Published: August 2015

PH (pleckstrin homology) domains represent the 11th most common domain in the human proteome. They are best known for their ability to bind phosphoinositides with high affinity and specificity, although it is now clear that less than 10% of all PH domains share this property. Cases in which PH domains bind specific phosphoinositides with high affinity are restricted to those phosphoinositides that have a pair of adjacent phosphates in their inositol headgroup. Those that do not [PtdIns3P, PtdIns5P and PtdIns(3,5)P2] are instead recognized by distinct classes of domains including FYVE domains, PX (phox homology) domains, PHD (plant homeodomain) fingers and the recently identified PROPPINs (b-propellers that bind polyphosphoinositides). Of the 90% of PH domains that do not bind strongly and specifically to phosphoinositides, few are well understood. One group of PH domains appears to bind both phosphoinositides (with little specificity) and Arf (ADP-ribosylation factor) family small G-proteins, and are targeted to the Golgi apparatus where both phosphoinositides and the relevant Arfs are both present. Here, the PH domains may function as coincidence detectors. A central challenge in understanding the majority of PH domains is to establish whether the very low affinity phosphoinositide binding reported in many cases has any functional relevance. For PH domains from dynamin and from Dbl family proteins, this weak binding does appear to be functionally important, although its precise mechanistic role is unclear. In many other cases, it is quite likely that alternative binding partners are more relevant, and that the observed PH domain homology represents conservation of structural fold rather than function.
Understanding the biological significance of diphosphoinositol polyphosphates (‘inositol pyrophosphates’)
Authors: Shears Stephen B.
Published: August 2015

Among the many derivatives of the inositol-based signalling family are a subgroup that possess diphosphates. In this review, some recent research into the actions of these specialized polyphosphates is analysed, and key goals for future studies are identified, which, it is hoped, will result in the wider cell-signalling community giving considerably greater attention to this intriguing but relatively neglected class of inositol polyphosphates.
Catalytic mechanism of chloramphenicol acetyltransferase investigated by site-directed mutagenesis
Authors: MURRAY IAIN A. , LEWENDON ANN , KLEANTHOUS COLIN , SHAW WILLIAM V.
Published: August 2015

Abbreviation used: CAT, chloramphenicol acetyltransferase.
Push–pull mode digital control for LLC series resonant dc‐to‐dc converters
Authors: Pidaparthy Syam K. , Jang Jinhaeng , Choi Byungcho
Published: August 2015

This study presents the design and performance evaluation of the digital control adapted to an LLC series resonant dc‐to‐dc converter operating with wide input and load variations. The proposed control design correctly incorporates the wide‐varying power stage dynamics and variable small‐signal gain of a digitally controlled oscillator, thereby offering satisfactory converter performance for all the operational conditions. The proposed digital controller adopts the push–pull mode control scheme, which executes the control action two times in one switching period, to minimise the time delay and enhance the performance. Using a 150 W experimental converter, the performance of the proposed push–pull mode digital control is demonstrated in comparison with that of the conventional complementary mode digital control, which performs the control action only once in one switching period.
Probing the structural and dynamical properties of liquid water with models including non-local electron correlation
Authors: Del Ben Mauro , Hutter Jürg , VandeVondele Joost
Published: August 2015

Water is a ubiquitous liquid that displays a wide range of anomalous properties and has a delicate structure that challenges experiment and simulation alike. The various intermolecular interactions that play an important role, such as repulsion, polarization, hydrogen bonding, and van der Waals interactions, are often difficult to reproduce faithfully in atomistic models. Here, electronic structure theories including all these interactions at equal footing, which requires the inclusion of non-local electron correlation, are used to describe structure and dynamics of bulk liquid water. Isobaric-isothermal (NpT) ensemble simulations based on the Random Phase Approximation (RPA) yield excellent density (0.994 g/ml) and fair radial distribution functions, while various other density functional approximations produce scattered results (0.8-1.2 g/ml). Molecular dynamics simulation in the microcanonical (NVE) ensemble based on Møller-Plesset perturbation theory (MP2) yields dynamical properties in the condensed phase, namely, the infrared spectrum and diffusion constant. At the MP2 and RPA levels of theory, ice is correctly predicted to float on water, resolving one of the anomalies as resulting from a delicate balance between van der Waals and hydrogen bonding interactions. For several properties, obtaining quantitative agreement with experiment requires correction for nuclear quantum effects (NQEs), highlighting their importance, for structure, dynamics, and electronic properties. A computed NQE shift of 0.6 eV for the band gap and absorption spectrum illustrates the latter. Giving access to both structure and dynamics of condensed phase systems, non-local electron correlation will increasingly be used to study systems where weak interactions are of paramount importance.
Massively parallel sampling of lattice proteins reveals foundations of thermal adaptation
Authors: Venev Sergey V. , Zeldovich Konstantin B.
Published: August 2015

Evolution of proteins in bacteria and archaea living in different conditions leads to significant correlations between amino acid usage and environmental temperature. The origins of these correlations are poorly understood, and an important question of protein theory, physics-based prediction of types of amino acids overrepresented in highly thermostable proteins, remains largely unsolved. Here, we extend the random energy model of protein folding by weighting the interaction energies of amino acids by their frequencies in protein sequences and predict the energy gap of proteins designed to fold well at elevated temperatures. To test the model, we present a novel scalable algorithm for simultaneous energy calculation for many sequences in many structures, targeting massively parallel computing architectures such as graphics processing unit. The energy calculation is performed by multiplying two matrices, one representing the complete set of sequences, and the other describing the contact maps of all structural templates. An implementation of the algorithm for the CUDA platform is available at http://www.github.com/kzeldovich/galeprot and calculates protein folding energies over 250 times faster than a single central processing unit. Analysis of amino acid usage in 64-mer cubic lattice proteins designed to fold well at different temperatures demonstrates an excellent agreement between theoretical and simulated values of energy gap. The theoretical predictions of temperature trends of amino acid frequencies are significantly correlated with bioinformatics data on 191 bacteria and archaea, and highlight protein folding constraints as a fundamental selection pressure during thermal adaptation in biological evolution.
Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse
Authors: Ma Y. , Chen L. M. , Li M. H. , Li Y. F. , Wang J. G. , Tao M. Z. , Han Y. J. , Zhao J. R. , Huang K. , Yan W. C. , Li D. Z. , Chen Z. Y. , Ma J. L. , Li Y. T. , Sheng Z. M. , Zhang J.
Published: August 2015

By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.
Delay-induced stochastic bifurcations in a bistable system under white noise
Authors: Sun Zhongkui , Fu Jin , Xiao Yuzhu , Xu Wei
Published: August 2015

In this paper, the effects of noise and time delay on stochastic bifurcations are investigated theoretically and numerically in a time-delayed Duffing-Van der Pol oscillator subjected to white noise. Due to the time delay, the random response is not Markovian. Thereby, approximate methods have been adopted to obtain the Fokker-Planck-Kolmogorov equation and the stationary probability density function for amplitude of the response. Based on the knowledge that stochastic bifurcation is characterized by the qualitative properties of the steady-state probability distribution, it is found that time delay and feedback intensity as well as noise intensity will induce the appearance of stochastic P-bifurcation. Besides, results demonstrated that the effects of the strength of the delayed displacement feedback on stochastic bifurcation are accompanied by the sensitive dependence on time delay. Furthermore, the results from numerical simulations best confirm the effectiveness of the theoretical analyses.
Material selection of a ferrimagnetic loaded coaxial delay line for phasing gyromagnetic nonlinear transmission lines
Authors: Johnson J. M. , Reale D. V. , Cravey W. H. , Garcia R. S. , Barnett D. H. , Neuber A. A. , Dickens J. C. , Mankowski J. J.
Published: August 2015

Implementing nonlinear transmission line (NLTL) technology in the design of a high power microwave source has the benefits of producing a comparatively small and lightweight solid-state system where the emission frequency is easily tuned. Usually, smaller in physical size, single NLTLs may produce significantly less power than its vacuum based counterparts. However, combining individual NLTL outputs electrically or in free-space is an attractive solution to achieve greater output power. This paper discusses a method for aligning a four element NLTL antenna array with coaxial geometry using easily adjustable temporal delay lines. These delay lines, sometimes referred to as pulse shock lines or pulse sharpening lines, are placed serially in front of the main NLTL line. The propagation velocity in each delay line is set by the voltage amplitude of an incident pulse as well as the magnetic field bias. Each is adjustable although for the system described in this paper, the voltage is held constant while the bias is changed through applying an external DC magnetic field of varying magnitude. Three different ferrimagnetic materials are placed in the temporal delay line to evaluate which yields the greatest range of electrical delay with the least amount of variability from consecutive shots.
High temperature coefficient of resistance of low-temperature-grown VO2 films on TiO2-buffered SiO2/Si (100) substrates
Authors: Miyazaki Kenichi , Shibuya Keisuke , Suzuki Megumi , Wado Hiroyuki , Sawa Akihito
Published: August 2015

The introduction of a TiO2 buffer layer significantly improved the temperature coefficient of resistance (TCR), a measure of the sharpness of the metal–insulator transition, for films of VO2 grown on SiO2/Si (100) substrates at growth temperatures below 670 K. X-ray diffraction and Raman scattering measurements revealed that polycrystalline VO2 films were formed on the TiO2-buffered substrates at low temperatures below 600 K, whereas amorphous films were formed at these temperatures on SiO2/Si (100) substrates without a TiO2 buffer layer. Electron microscopy studies confirmed that the TiO2 buffer layer enhanced the grain growth of VO2 films at low growth temperatures. The VO2 films grown at 600 K on TiO2-buffered substrates showed a large TCR of more than 80%/K as a result of the improved crystallinity and grain size of the VO2 films. Our results provide an effective approach toward the integration of VO2-based devices onto Si platforms at process temperatures below 670 K.
Observation of the Rayleigh-Bénard convection cells in strongly coupled Yukawa liquids
Authors: Charan Harish , Ganesh Rajaraman
Published: August 2015

Using “first principles” molecular dynamics simulation, we report for the first time the formation of Rayleigh-Bénard convection cells (RBCC) in two-dimensional strongly coupled Yukawa liquids, characterized by coupling strength Γ (ratio of average potential energy to kinetic energy per particle) and screening parameter κ (ratio of average inter-particle distance to Debye length). For typical values of (Γ, κ), existence of a critical external temperature difference is demonstrated, beyond which RBCC are seen to set in. Beyond this critical external temperature difference, the strength of the maximum convective flow velocity is shown to exhibit a new, hitherto unsuspected linear relationship with external temperature difference and with a slope independent of (Γ, κ). The time taken for the transients to settle down (τs) to a steady state RBCC is found to be maximum close to the above said critical external temperature difference and is seen to reduce with increasing external temperature difference. For the range of values of (Γ, κ) considered here, τs ≈ 10 000–20 000 ωpd−1, where ωpd is dust plasma frequency. As Γ is increased to very high values, due to strong coupling effects, cells are seen to be in a transient state without attaining a steady state for as long as 100 000 ωpd−1, even for a very high external temperature difference. Role of system size, aspect ratio, and dust-neutral collisions has also been addressed.
Highly stretchable carbon nanotube transistors enabled by buckled ion gel gate dielectrics
Authors: Wu Meng-Yin , Zhao Juan , Xu Feng , Chang Tzu-Hsuan , Jacobberger Robert M. , Ma Zhenqiang , Arnold Michael S.
Published: August 2015

Deformable field-effect transistors (FETs) are expected to facilitate new technologies like stretchable displays, conformal devices, and electronic skins. We previously demonstrated stretchable FETs based on buckled thin films of polyfluorene-wrapped semiconducting single-walled carbon nanotubes as the channel, buckled metal films as electrodes, and unbuckled flexible ion gel films as the dielectric. The FETs were stretchable up to 50% without appreciable degradation in performance before failure of the ion gel film. Here, we show that by buckling the ion gel, the integrity and performance of the nanotube FETs are extended to nearly 90% elongation, limited by the stretchability of the elastomer substrate. The FETs maintain an on/off ratio of >104 and a field-effect mobility of 5 cm2 V−1 s−1 under elongation and demonstrate invariant performance over 1000 stretching cycles.
Optical emission, shock-induced opacity, temperatures, and melting of Gd3Ga5O12 single crystals shock-compressed from 41 to 290 GPa
Authors: Zhou Xianming , Nellis William J. , Li Jiabo , Li Jun , Zhao Wanguang , Liu Xun , Cao Xiuxia , Liu Qiancheng , Xue Tao , Wu Qiang , Mashimo T.
Published: August 2015

Strong oxides at high shock pressures have broad crossovers from elastic solids at ambient to failure by plastic deformation, to heterogeneous deformation to weak solids, to fluid-like solids that equilibrate thermally in a few ns, to melting and, at sufficiently high shock pressures and temperatures, to metallic fluid oxides. This sequence of crossovers in single-crystal cubic Gd3Ga5O12 (Gd-Ga Garnet-GGG) has been diagnosed by fast emission spectroscopy using a 16-channel optical pyrometer in the spectral range 400–800 nm with bandwidths per channel of 10 nm, a writing time of ∼1000 ns and time resolution of 3 ns. Spectra were measured at shock pressures from 40 to 290 GPa (100 GPa = 1 Mbar) with corresponding gray-body temperatures from 3000 to 8000 K. Experimental lifetimes were a few 100 ns. Below 130 GPa, emission is heterogeneous and measured temperatures are indicative of melting temperatures in grain boundary regions rather than bulk temperatures. At 130 GPa and 2200 K, GGG equilibrates thermally and homogeneously in a thin opaque shock front. This crossover has a characteristic spectral signature in going from partially transmitting shock-heated material behind the shock front to an opaque shock front. Opacity is caused by optical scattering and absorption of light generated by fast compression. GGG melts at ∼5000 K in a two-phase region at shock pressures in the range 200 GPa to 217 GPa. Hugoniot equation-of-state data were measured by a Doppler Pin SystemDPS with ps time resolution and are generally consistent with previous data. Extrapolation of previous electrical conductivity measurements indicates that GGG becomes a poor metal at a shock pressure above ∼400 GPa. Because the shock impedance of GGG is higher than that of Al2O3 used previously to make metallic fluid H (MFH), the use of GGG to make MFH will achieve higher pressures and lower temperatures than use of Al2O3. However, maximum dynamic pressures at which emission temperatures of fluid hydrogen made by shock reverberation between GGG anvils could be measured remains limited to ∼130 GPa, as for Al2O3 anvils.
Interaction between pulsed discharge and radio frequency discharge burst at atmospheric pressure
Authors: Zhang Jie , Guo Ying , Shi Yuncheng , Zhang Jing , Shi J. J.
Published: August 2015

The atmospheric pressure glow discharges (APGD) with dual excitations in terms of pulsed voltage and pulse-modulation radio frequency (rf) power are studied experimentally between two parallel plates electrodes. Pulse-modulation applied in rf APGD temporally separates the discharge into repetitive discharge bursts, between which the high voltage pulses are introduced to ignite sub-microsecond pulsed discharge. The discharge characteristics and spatio-temporal evolution are investigated by means of current voltage characteristics and time resolved imaging, which suggests that the introduced pulsed discharge assists the ignition of rf discharge burst and reduces the maintain voltage of rf discharge burst. Furtherly, the time instant of pulsed discharge between rf discharge bursts is manipulated to study the ignition dynamics of rf discharge burst.
Nonlinear organic plasmonics: Applications to optical control of Coulomb blocking in nanojunctions
Authors: Fainberg B. D. , Li G.
Published: August 2015

Purely organic materials with negative and near-zero dielectric permittivity can be easily fabricated. Here, we develop a theory of nonlinear non-steady-state organic plasmonics with strong laser pulses that enable us to obtain near-zero dielectric permittivity during a short time. Our consideration is based on the model of the interaction of strong (phase modulated) laser pulse with organic molecules developed by one of the authors before, extended to the dipole-dipole intermolecular interactions in the condensed matter. We have proposed to use non-steady-state organic plasmonics for the enhancement of intersite dipolar energy-transfer interaction in the quantum dot wire that influences on electron transport through nanojunctions. Such interactions can compensate Coulomb repulsions for particular conditions. We propose the exciton control of Coulomb blocking in the quantum dot wire based on the non-steady-state near-zero dielectric permittivity of the organic host medium.
Strong reflection and periodic resonant transmission of helical edge states in topological-insulator stub-like resonators
Authors: Takagaki Y.
Published: August 2015

The helical edge states of two-dimensional topological insulators (TIs) experience appreciable quantum mechanical scattering in narrow channels when the width changes abruptly. The interference of the geometry scattering in narrow-wide-narrow waveguide structures is shown to give rise to the strong suppression of transmission when the incident energy is barely above the propagation threshold. Periodic resonant transmission takes place in this high reflection regime while the length of the wide section is varied. The resonance condition is governed by the transverse confinement in the wide section, where the form of quantization is manifested to differ for the two orthogonal directions. The confined energy levels in TI quantum dots are derived based on this observation. In addition, the off-diagonal spin-orbit term is found to produce an anomalous resonance state, which merges with the bottom ordinary resonance state to annihilate.
Electrical injection to contactless near-surface InGaN quantum well
Authors: Riuttanen L. , Kivisaari P. , Svensk O. , Oksanen J. , Suihkonen S.
Published: August 2015

Charge injection to the prevailing and emerging light-emitting devices is almost exclusively based on the double heterojunction (DHJ) structures that have remained essentially unchanged for decades. In this letter, we report the excitation of a near surface indium gallium nitride (InGaN) quantum well (QW) by bipolar carrier diffusion from a nearby electrically excited pn-homojunction. The demonstrated near surface QW emitter is covered only by a 10 nm GaN capping leaving the light-emitting mesa perfectly free of metals, other contact, or current spreading structures. The presented proof-of-principle structure, operating approximately with a quantum efficiency of one fifth of a conventional single QW reference structure, provides conclusive evidence of the feasibility of using diffusion injection to excite near surface light-emitting structures needed, e.g., for developing light emitters or photo-voltaic devices based on nanoplasmonics or free-standing nanowires. In contrast to the existing DHJ solutions or optical pumping, our approach allows exciting nanostructures without the need of forming a DHJ, absorbing layers or even electrical contacts on the device surface.
Spatial and temporal variation of meiofauna community structure in soft-sediment pools around Moreton Bay, Australia
Authors: Chargulaf Craig A. , Tibbetts Ian R.
Published: August 2015

In eastern Australia, small ephemeral soft-sediment pools are common on sheltered sand- and mudflats, and are occupied by the juveniles of fishes of economic and ecological importance. To address the question of whether these pools are merely refugia or whether they constitute a hitherto unrecognised nursery feeding habitat for small obligate meiobenthivorous fishes, we surveyed the meiofaunal communities of ephemeral soft-sediment pools within three intertidal shores of Moreton Bay, Australia. Highest mean meiofaunal abundances occurred at Godwin Beach and differed significantly throughout the year. Nematodes and copepods were the most abundant taxa while all other taxa contributed to <10% of the total meiofaunal abundance. Pool characteristics (i.e. volume and surface area) did not correlate with the abundance of benthic faunal assemblages. Overall, ephemeral soft-sediment pools of Moreton Bay support meiofaunal communities that are likely to provide prey resources for juvenile and small fish that use them as nurseries at low tide.
Heterochrony underpins natural variation inCardamine hirsutaleaf form
Authors: Cartolano Maria , Pieper Bjorn , Lempe Janne , Tattersall Alex , Huijser Peter , Tresch Achim , Darrah Peter R. , Hay Angela , Tsiantis Miltos
Published: August 2015

Significance

A key problem in biology is whether the same processes underlie morphological variation between and within species. Here, we show that the causes of leaf shape diversity at these two evolutionary scales can be divergent. Some species have simple leaves, whereas others bear complex leaves comprising leaflets. Previous work indicated that these interspecific differences result mostly from variation in local tissue growth and patterning. Now we find that a different process, age-dependent shape progression, underlies within-species variation in complex leaf morphology. Specifically, in plants with accelerated aging and early flowering, leaves progress to adult shapes with more leaflets, faster than their slower-aging counterparts. This mechanism coordinates leaf development with reproductive timing and may influence resource allocation to seeds.
IL-33 promotes an innate immune pathway of intestinal tissue protection dependent on amphiregulin–EGFR interactions
Authors: Monticelli Laurel A. , Osborne Lisa C. , Noti Mario , Tran Sara V. , Zaiss Dietmar M. W. , Artis David
Published: August 2015

Significance

Mammalian barrier surfaces are exposed to environmental stimuli that can result in tissue damage. Interleukin (IL)-33–dependent group 2 innate lymphoid cells (ILC2s) are enriched at barrier sites, but the mechanisms underlying the tissue-protective roles of IL-33 or ILC2s in the intestine remain poorly defined. Here we use a model of murine intestinal inflammation and reveal a previously unrecognized pathway of innate immune cell-mediated tissue protection in which IL-33 ameliorated disease through induction of ILC2s and the growth factor amphiregulin (AREG). Collectively, these data highlight a critical dialogue between damaged epithelia and innate immune cells and indicate that manipulation of the IL-33–ILC2–AREG pathway could provide therapeutic benefit in treatment of intestinal inflammatory diseases.
Finding the Path to a Successful Graduate and Research Career: Advice for Early Career Researchers
Authors: Maitland Bryan M. , Cooke Steven J. , Poesch Mark
Published: August 2015

The path to a successful graduate and research career is a complex and difficult one. Early career researchers (ECRs) have myriad choices and tasks to prioritize and complete as they build their CV but are often confronted with unfamiliar situations in which advice from more senior researchers can be extremely valuable. Here, we summarize a recent workshop held for ECRs by the Canadian Aquatic Resource Section of the American Fisheries Society (AFS) with support from the Education Section. Sessions touched on (1) getting published, (2) science communication and outreach, (3) scoring a job or grad school position, and (4) working within the science–policy interface. The decades of collective experience brought to the table should be shared with the broader readership of AFS because it may prove useful to ECRs as well as stimulate meaningful conversations on these important and timely issues.

El camino hacia una graduación exitosa y una carrera en la investigación es complejo y difícil. Los investigadores incipientes (II; aquellos que se encuentran en las primeras etapas de su carrera) tienen ante sí una miríada de opciones y retos que deben priorizar y completar a medida que construyen su CV, sin embargo suelen enfrentarse a situaciones poco familiares en las cuales el consejo de investigadores más experimentados puede resultar muy valioso. En este artículo se resume un taller de trabajo llevado a cabo recientemente para los II por parte de la sección de Recursos Acuáticos de Canadá, de la Sociedad Americana de Pesquerías (SAP), con la colaboración de la Sección de Educación. Las sesiones trataron de 1) publicación; 2) extensión y comunicación de la ciencia; 3) conseguir un trabajo o una posición en una escuela; y 4) trabajar en la interface ciencia-políticas públicas. Las décadas de experiencia colectiva puestas sobre la mesa de discusión debieran compartirse con un público más amplio de la SAP, dado que pudiera ser útil para los II así como también para estimular conversaciones productivas en estos temas de actualidad.
Injuries and musculoskeletal pain among Norwegian group fitness instructors
Authors: Bratland‐Sanda Solfrid , Sundgot‐Borgen Jorunn , Myklebust Grethe
Published: August 2015

Objective: To examine the prevalence and factors associated with instruction‐related injuries and musculoskeletal pain among group fitness instructors. Design: Descriptive epidemiology study. Settings: Online survey. Participants: Group fitness instructors from three fitness centre companies in Norway (n = 1473). Assessment of independent variables: questions regarding duration of working as a group fitness instructor, weekly instruction and exercise loading and modality, instruction‐related injuries, musculoskeletal pain, use of alcohol, tobacco, snuff, menstrual dysfunction and disordered eating (Eating Disorder Inventory, EDI). The respondents were divided into high instruction loading (HIL), ≥5 h/w with instruction; and low instruction loading (LIL), <5 h/w with instruction). Results: The response rate was 57% (n = 837). Mean total loading (instruction and exercise) was 11.8 h/w and 6.3 h/w in the HIL and LIL groups (p < .001), respectively. The prevalence of acute (9% vs. 6%, p < .05), overuse (38% vs. 24%, p < .001) and both acute and overuse injuries (25% vs. 10%, p < .001) was higher in the HIL than in the LIL group (OR: 3.9, CI: 2.7, 5.5). The most prevalent injury locations were ankle and lower leg. The most frequent location for musculoskeletal pain was the shoulder/neck region. Factors associated with injury were instruction loading (h/w), years working as an instructor and EDI score. A high total EDI score predicted musculoskeletal pain. Conclusion: The high prevalence of injuries and musculoskeletal pain suggests a need for prevention strategies in the fitness industry. There is a need for limits regarding weekly instruction loading, especially for classes with high metabolic and/or mechanical loading.
Impaired Pain-evoked Analgesia after Nerve Injury in Rats Reflects Altered Glutamate Regulation in the Locus Coeruleus
Authors: Kimura Masafumi , Suto Takashi , Morado-Urbina Carlos E. , Peters Christopher M. , Eisenach James C. , Hayashida Ken-Ichiro
Published: August 2015

AbstractAbstract

The authors investigated the circuitry for impaired noxious stimulation–induced analgesia in rats with neuropathic pain. The authors demonstrate glutamate dysregulation in the locus coeruleus, and the resulting impairment of descending inhibitory control contributes to the loss of noxious stimulation–induced analgesia in neuropathic pain.

Background:

Patients with neuropathic pain show reduced endogenous analgesia induced by a conditioned noxious stimulus. Here, the authors tested whether peripheral nerve injury impairs descending noradrenergic inhibition from the locus coeruleus (LC) after L5–L6 spinal nerve ligation (SNL) in rats.

Methods:

A subdermal injection of capsaicin was used to examine noxious stimulation–induced analgesia (NSIA), evoked LC glutamate and spinal noradrenaline release, and evoked LC neuronal activity in normal and SNL rats. The authors also examined the role of presynaptic metabotropic glutamate receptors or the astroglial glutamate transporter-1 (GLT-1).

Results:

SNL increased basal extracellular glutamate concentration in the LC (170.1%; 95% CI, 44.7 to 295.5; n = 15) and basal spinal cord noradrenaline release (252.1%; 95% CI, 113.6 to 391.3; n = 15), which was associated with an increased tonic LC neuronal activity and a down-regulation of GLT-1 in the LC. SNL reduced NSIA (−77.6%; 95% CI, −116.4 to −38.8; n = 14) and capsaicin evoked release of glutamate in the LC (−36.2%; 95% CI, −49.3 to −23.2; n = 8) and noradrenaline in the spinal cord (−38.8%; 95% CI, −45.1 to −32.5; n = 8). Capsaicin-evoked LC neuronal activation was masked in SNL rats. Removing autoinhibition of glutamatergic terminals by metabotropic glutamate receptor blockade or increasing GLT-1 expression by histone deacetylase inhibition restored NSIA in SNL rats. SNL-induced impairment of NSIA was mimicked in normal rats by knockdown of GLT-1 in the LC.

Conclusions:

These results suggest that increased extracellular glutamate in the LC consequent to down-regulation of GLT-1 contributes to LC dysfunction and impaired pain-evoked endogenous analgesia after nerve injury.
Crystal structure of 2-azido-1H-imidazole-4,5-dicarbonitrile
Authors: Windler G. Kenneth , Scott Brian L. , Tomson Neil C. , Leonard Philip W.
Published: August 2015

In the title compound, C5HN7, the nitrile and azido substituents are close to being coplanar with the central ring. Molecules in the crystal are linkedviaan N—H...N hydrogen bond to a nitrile acceptor, forming a chain extending along thec-axis direction.
Crystal structure ofN-(2-{[2,6-bis(2,2,2-trifluoroacetamido)phenyl]disulfanyl}-3-(2,2,2-trifluoroacetamido)phenyl)-2,2,2-trifluoroacetamide
Authors: Awasabisah Dennis , Powell Douglas R. , Richter-Addo George B.
Published: August 2015

The title compound, C20H10F12N4O4S2, is an organic diaryl disulfide compound with trifluoroacetamide substituents at theortho-positions of each benzene ring. There are two molecules (labeledAandB) in the asymmetric unit. The F atoms of three of the –CF3groups exhibit rotational disorder over two positions each. The S—S bond distances are 2.0914 (7) and 2.0827 (6) Å for moleculesAandB, respectively. The dihedral angle between the S—S—C and S—C—C planes is 103.05 (15)° for moleculeAand 104.09 (15)° for moleculeB. The three-dimensional supramolecular architecture of the crystal is sustained by numerous N—H...O, N—H...S and C—H...O interactions.