bluuebunny/crossref_metadata_2025 huggingface dataset:
Solvent-controlled growth of silicone nanofilaments
Authors: Zhang Junping , Li Lingxiao , Li Bucheng , Seeger Stefan
Published: July 2014

Silicone nanofilaments (SNFs) with different features and hydrophobicity were prepared by regulating solvent composition during the hydrolysis and condensation of trichloromethylsilane.
One-step synthesis of noble metal/oxide nanocomposites with tunable size of noble metal particles and their size-dependent catalytic activity
Authors: Liu Jie , Wang Wei , Shen Tong , Zhao Zhiwei , Feng Hui , Cui Fuyi
Published: July 2014

A general one-step synthesis of noble metal/oxide nanocomposites with tunable size of noble metal particles and size-dependent catalytic activity.
Mesoporous VO2 nanowires with excellent cycling stability and enhanced rate capability for lithium batteries
Authors: Zhang Lei , Zhao Kangning , Xu Wangwang , Meng Jiashen , He Liang , An Qinyou , Xu Xu , Luo Yanzhu , Zhao Tingwei , Mai Liqiang
Published: July 2014

To combine the merits of the one-dimensional structure and the porous structure, mesoporous VO2 nanowires have been designed and reported for the first time.
Promising alkoxy-wrapped porphyrins with novel push–pull moieties for dye-sensitized solar cells
Authors: Zhang Ming-Dao , Zhang Zi-Yang , Bao Zhong-Qiu , Ju Ze-Min , Wang Xing-Yong , Zheng He-Gen , Ma Jing , Zhou Xing-Fu
Published: July 2014

This paper focuses on the structure modification of sensitizers for efficient porphyrin-sensitized solar cells (PSSCs).
Nanocups-on-microtubes: a unique host towards high-performance lithium ion batteries
Authors: Kong Junhua , Zhao Chenyang , Wei Yuefan , Phua Si Lei , Dong Yuliang , Lu Xuehong
Published: July 2014

Carbonaceous nanocups attached on free-standing microtubes were prepared and used to trap MoS2 nanosheets. Excellent cyclability and rate performance were achieved owing to efficient contact between the nanocups, nanosheets and electrolyte.
Molecular weight and end capping effects on the optoelectronic properties of structurally related ‘heavy atom’ donor–acceptor polymers
Authors: Gibson Gregory L. , Gao Dong , Jahnke Ashlee A. , Sun Jing , Tilley Andrew J. , Seferos Dwight S.
Published: July 2014

Molecular weight and end group differences produce distinct optoelectronic and morphological properties in heavy atom donor–acceptor polymers of the same repeat unit structure.
Microporous titanate nanofibers for highly efficient UV-protective transparent coating
Authors: Hattori H. , Ide Y. , Sano T.
Published: July 2014

Interzeolite conversion was applied to convert a layered titanate into a microporous titanate nanofiber, which hardly showed photocatalytic activity and exhibited extremely low refractive index and then could be used as a UV absorber embedded in commodity organic polymer coatings.
Zeolitic imidazolate framework materials: recent progress in synthesis and applications
Authors: Chen Binling , Yang Zhuxian , Zhu Yanqiu , Xia Yongde
Published: July 2014

Recent progress in the synthesis and applications of zeolitic imidazolate framework materials is presented in this review.
Tetraphenylethene-decorated carbazoles: synthesis, aggregation-induced emission, photo-oxidation and electroluminescence
Authors: Gong Wen-Liang , Wang Bo , Aldred Matthew. P. , Li Chong , Zhang Guo-Feng , Chen Tao , Wang Lei , Zhu Ming-Qiang
Published: July 2014

Tetraphenylethene-decorated carbazoles with aggregation-induced emission (AIE) have been synthesized while aggregation-caused quenching have been observed after photo-oxidation.
In vitrostudies on the reaction rates of acrylamide with the key body-fluid thiolsl-cysteine, glutathione, and captopril
Authors: Bent Grace-Anne , Maragh Paul , Dasgupta Tara
Published: July 2014

The mechanisms of interactions of acrylamide with l-cysteine, glutathione and captopril were studied in vitro. Experimental second order rate constants calculated at 303 K were 0.34 ± 0.02, 0.18 ± 0.02, and 0.13 ± 0.01 dm3 mol−1 s−1 for l-cysteine, glutathione, and captopril, respectively, potentially involving inter- and intra-molecular H-bonding in the acrylamide-glutathione complex.
Improving the oxidation potential of Sb-doped SnO2 electrode by Zn/Sb co-doping
Authors: Chen Aqing , Bin Li Bin , Miljkovic Bojan , Souza Christina , Zhu Kaigui , Ruda Harry E.
Published: July 2014

Inorganic oxides are recognized as attractive materials for developing anodes for wastewater treatment, potentially offering a cost effective solution for electro-oxidation. A key parameter in measuring the effectiveness of different anode materials is the oxygen over potential. In this paper, we study the role of Zn and Sb co-doping of SnO2 thin films to achieve enhanced oxidation potentials, suitable for use in wastewater treatment. The morphology, chemical, and electrochemical properties of the films were characterized, and as a result of an optimization study, suitable anode materials for wastewater treatment are identified.
Effects of spin doping and spin injection in the luminescence and vibrational spectrum of C60
Authors: Moorsom Timothy , Wheeler May , Taukeer Khan Mohd , Al Ma'Mari Fatma , Burnell Gavin , Hickey Bryan J. , Lazarov Vlado , Gilks Daniel , Cespedes Oscar
Published: July 2014

We have studied the Raman spectrum and photoemission of hybrid magneto-fullerene devices. For C60 layers on cobalt, the spin polarized electron transfer shifts the photoemission energy, reducing the zero phonon contribution. The total luminescence of hybrid devices can be controlled via spin injection from magnetic electrodes, with changes of the order of 10%–20% at room temperature. Spin polarised currents alter as well the Raman spectrum of the molecules, enhancing some modes by a factor 5 while shifting others by several wavenumbers due to a spin-dependent hopping time and/or enhanced intermolecular interactions. These results can be used to measure spin polarisation in molecules or to fabricate magneto-optic and magneto-vibrational devices.
An evaluation system for experimental silicon and silicon carbide super gate turn off thyristors
Authors: Bayne Stephen , Lacouture Shelby , Lawson Kevin , Giesselmann Michael , Scozzie Charles J. , O’Brien Heather , Ogunniyi Aderinto A.
Published: July 2014

This paper describes the design and implementation of a small-scale pulsed power system specifically intended to evaluate the suitability of experimental silicon and silicon carbide high power Super Gate Turn Off thyristors for high action (500 A2 s and above) pulsed power applications where energy is extracted from a storage element in a rapid and controlled manner. To this end, six of each type of device was placed in a controlled three phase rectifier circuit which was in turn connected to an aircraft ground power motor-generator set and subjected to testing protocols with varying power levels, while parameters such as offset firing angle were varied.
Measurement of electron temperature fluctuations using a tunable correlation electron cyclotron emission system on Alcator C-Mod
Authors: Howard N. T. , Sung C. , White A. E.
Published: July 2014

A tunable correlation electron cyclotron (CECE) system was recently installed on the Alcator C-Mod tokamak to provide local, quantitative measurement of electron temperature fluctuations in the tokamak core. This system represents a significant upgrade from the original CECE system, expanding the measurement capabilities from 4 to 8 total channels, including 2 remotely tunable YIG filters (6–18 GHz; 200 MHz bandwidth). Additional upgrades were made to the optical system to provide enhanced poloidal resolution and allow for measurement of turbulent fluctuations below kθρs < 0.3. These expanded capabilities allow for single shot measurement of partial temperature fluctuation profiles in the region ρ = 0.7 − 0.9 (square root of normalized toroidal flux) in a wide variety of plasma conditions. These measurements are currently being used to provide stringent tests of the gyrokinetic model in ongoing model validation efforts. Details of the hardware upgrades, turbulent fluctuation measurements, and ongoing comparisons with simulations are presented.
Water interactions with hydrophobic groups: Assessment and recalibration of semiempirical molecular orbital methods
Authors: Marion Antoine , Monard Gérald , Ruiz-López Manuel F. , Ingrosso Francesca
Published: July 2014

In this work, we present a study of the ability of different semiempirical methods to describe intermolecular interactions in water solution. In particular, we focus on methods based on the Neglect of Diatomic Differential Overlap approximation. Significant improvements of these methods have been reported in the literature in the past years regarding the description of non-covalent interactions. In particular, a broad range of methodologies has been developed to deal with the properties of hydrogen-bonded systems, with varying degrees of success. In contrast, the interactions between water and a molecule containing hydrophobic groups have been little analyzed. Indeed, by considering the potential energy surfaces obtained using different semiempirical Hamiltonians for the intermolecular interactions of model systems, we found that none of the available methods provides an entirely satisfactory description of both hydrophobic and hydrophilic interactions in water. In addition, a vibrational analysis carried out in a model system for these interactions, a methane clathrate cluster, showed that some recent methods cannot be used to carry out studies of vibrational properties. Following a procedure established in our group [M. I. Bernal-Uruchurtu, M. T. C. Martins-Costa, C. Millot, and M. F. Ruiz-López, J. Comput. Chem. 21, 572 (2000); W. Harb, M. I. Bernal-Uruchurtu, and M. F. Ruiz-López, Theor. Chem. Acc. 112, 204 (2004)], we developed new parameters for the core-core interaction terms based on fitting potential energy curves obtained at the MP2 level for our model system. We investigated the transferability of the new parameters to describe a system, having both hydrophilic and hydrophobic groups, interacting with water. We found that only by introducing two different sets of parameters for hydrophilic and hydrophobic hydrogen atom types we are able to match the features of the ab initio calculated properties. Once this assumption is made, a good agreement with the MP2 reference is achieved. The results reported in this work provide therefore a direction for future developments of semiempirical approaches that are still required to investigate chemical processes in biomolecules and in large disordered systems.
Chemical potential of liquids and mixtures via adaptive resolution simulation
Authors: Agarwal Animesh , Wang Han , Schütte Christof , Site Luigi Delle
Published: July 2014

We employ the adaptive resolution approach AdResS, in its recently developed Grand Canonical-like version (GC-AdResS) [H. Wang, C. Hartmann, C. Schütte, and L. Delle Site, Phys. Rev. X 3, 011018 (2013)], to calculate the excess chemical potential, μex, of various liquids and mixtures. We compare our results with those obtained from full atomistic simulations using the technique of thermodynamic integration and show a satisfactory agreement. In GC-AdResS, the procedure to calculate μex corresponds to the process of standard initial equilibration of the system; this implies that, independently of the specific aim of the study, μex, for each molecular species, is automatically calculated every time a GC-AdResS simulation is performed.
Dynamics of swimming bacteria at complex interfaces
Authors: Lopez Diego , Lauga Eric
Published: July 2014

Flagellated bacteria exploiting helical propulsion are known to swim along circular trajectories near surfaces. Fluid dynamics predicts this circular motion to be clockwise (CW) above a rigid surface (when viewed from inside the fluid) and counter-clockwise (CCW) below a free surface. Recent experimental investigations showed that complex physicochemical processes at the nearby surface could lead to a change in the direction of rotation, both at solid surfaces absorbing slip-inducing polymers and interfaces covered with surfactants. Motivated by these results, we use a far-field hydrodynamic model to predict the kinematics of swimming near three types of interfaces: clean fluid-fluid interface, slipping rigid wall, and a fluid interface covered by incompressible surfactants. Representing the helical swimmer by a superposition of hydrodynamic singularities, we first show that in all cases the surfaces reorient the swimmer parallel to the surface and attract it, both of which are a consequence of the Stokes dipole component of the swimmer flow field. We then show that circular motion is induced by a higher-order singularity, namely, a rotlet dipole, and that its rotation direction (CW vs. CCW) is strongly affected by the boundary conditions at the interface and the bacteria shape. Our results suggest thus that the hydrodynamics of complex interfaces provide a mechanism to selectively stir bacteria.
Total power millimeter-wave spectrometer for measurements of dust opacity at cryogenic temperatures
Authors: Potapov Alexey , Lewen Frank , Mutschke Harald , Mohr Pierre , Schlemmer Stephan
Published: July 2014

A highly sensitive total power millimeter-wave spectrometer has been built to investigate the opacity of important interstellar-dust analogues in the 10–300 K temperature range. The key elements of the spectrometer are a frequency agile synthesizer followed by a microwave amplifier and a subsequent frequency multiplier. In a first step, the frequency range of 72–120 GHz is covered by the spectrometer, and a room temperature Schottky detector is employed as a detector. A newly developed two channel (sample/reference) copper sample holder is cryogenically cooled for the 10–300 K range. Here we present the technical details of the spectrometer including examples of the obtained results. The analysis of these results will be published elsewhere.
Pulsed DC magnetron sputtered piezoelectric thin film aluminum nitride – Technology and piezoelectric properties
Authors: Stoeckel C. , Kaufmann C. , Hahn R. , Schulze R. , Billep D. , Gessner T.
Published: July 2014

Pulsed DC magnetron sputtered aluminum nitride (AlN) thin films are prepared on several seed layers and at different sputtering conditions. The piezoelectric c-axis (002) orientation of the AlN is analyzed with X-ray diffraction method. The transverse piezoelectric coefficient d31 is determined with a Laser-Doppler-Vibrometer at cantilevers and membranes by analytical calculations and finite element method. Additionally, thin film AlN on bulk silicon is used to characterize the longitudinal piezoelectric charge coefficient d33.
Optically tunable spin-exchange energy at donor:acceptor interfaces in organic solar cells
Authors: Li Mingxing , Wang Hongfeng , He Lei , Zang Huidong , Xu Hengxing , Hu Bin
Published: July 2014

Spin-exchange energy is a critical parameter in controlling spin-dependent optic, electronic, and magnetic properties in organic materials. This article reports optically tunable spin-exchange energy by studying the line-shape characteristics in magnetic field effect of photocurrent developed from intermolecular charge-transfer states based on donor:acceptor (P3HT:PCBM) system. Specifically, we divide magnetic field effect of photocurrent into hyperfine (at low field < 10 mT) and spin-exchange (at high field > 10 mT) regimes. We observe that increasing photoexcitation intensity can lead to a significant line-shape narrowing in magnetic field effect of photocurrent occurring at the spin-exchange regime. We analyze that the line-shape characteristics is essentially determined by the changing rate of magnetic field-dependent singlet/triplet ratio when a magnetic field perturbs the singlet-triplet transition through spin mixing. Based on our analysis, the line-shape narrowing results indicate that the spin-exchange energy at D:A interfaces can be optically changed by changing photoexcitation intensity through the interactions between intermolecular charge-transfer states. Therefore, our experimental results demonstrate an optical approach to change the spin-exchange energy through the interactions between intermolecular charge-transfer states at donor:acceptor interface in organic materials.
Efficient methylammonium lead iodide perovskite solar cells with active layers from 300 to 900 nm
Authors: Momblona C. , Malinkiewicz O. , Roldán-Carmona C. , Soriano A. , Gil-Escrig L. , Bandiello E. , Scheepers M. , Edri E. , Bolink H. J.
Published: July 2014

Efficient methylammonium lead iodide perovskite-based solar cells have been prepared in which the perovskite layer is sandwiched in between two organic charge transporting layers that block holes and electrons, respectively. This configuration leads to stable and reproducible devices that do not suffer from strong hysteresis effects and when optimized lead to efficiencies close to 15%. The perovskite layer is formed by using a dual-source thermal evaporation method, whereas the organic layers are processed from solution. The dual-source thermal evaporation method leads to smooth films and allows for high precision thickness variations. Devices were prepared with perovskite layer thicknesses ranging from 160 to 900 nm. The short-circuit current observed for these devices increased with increasing perovskite layer thickness. The main parameter that decreases with increasing perovskite layer thickness is the fill factor and as a result optimum device performance is obtained for perovskite layer thickness around 300 nm. However, here we demonstrate that with a slightly oxidized electron blocking layer the fill factor for the solar cells with a perovskite layer thickness of 900 nm increases to the same values as for the devices with thin perovskite layers. As a result the power conversion efficiencies for the cells with 300 and 900 nm are very similar, 12.7% and 12%, respectively.
Two-dimensional ultra-small angle X-ray scattering with grating interferometry
Authors: Modregger P. , Rutishauser S. , Meiser J. , David C. , Stampanoni M.
Published: July 2014

It was recently established that the pixel-wise ultra-small angle x-ray distribution can be retrieved with grating interferometry. However, in these one dimensional approaches the contrast was limited to the direction orthogonal to the structure of the line gratings. Here, we demonstrate that sensitivity in two contrast directions can be achieved by using two pairs of crossed line gratings and by adapting scan procedures and data analysis accordingly. We demonstrate the retrieval of two-dimensional scattering distributions with grating interferometry, thus overcoming the previously reported limit of seven obtainable, complementary contrasts. In addition, we give further evidence for the superiority of the signal-to-noise ratio for the dark-field contrast, if a deconvolution-based instead of the standard analysis is utilized.
Band-Gap tuned oscillatory conductance in bilayer graphene n-p-n junction
Authors: Park Chang-Soo
Published: July 2014

We study transmission of quasiparticles through a bilayer graphene n-p-n junction when the particle energy lies within the band gap produced by external gate fields. The dispersion relation of eigenspectrum allows two pairs of complex-conjugate wave vectors inside the barrier region, so that two types of common paths, [R. Nandkishore and L. Levitov, Proc. Natl. Acad. Sci. 108, 14021 (2011)] one with decaying amplitude and the other with growing amplitude, contribute to the transmission. Each common path produces interference effect of oscillatory transmissions, with vanishing tunneling probabilities at certain values of the band gap and incident angles. We explain this interference effect by using a semiclassical approximation of path integral approach and show that multiple reflection of forward and backward propagations inside the barrier does not destroy the common-path interference. As a result of the interference, we demonstrate that the conductance through the barrier oscillates as a function of the band gap.
Magnetic behavior of NiCu nanowire arrays: Compositional, geometry and temperature dependence
Authors: Palmero E. M. , Bran C. , del Real R. P. , Magén C. , Vázquez M.
Published: July 2014

Arrays of Ni100−xCux nanowires ranging in composition 0 ≤ x ≤ 75, diameter from 35 to 80 nm, and length from 150 nm to 28 μm have been fabricated by electrochemical co-deposition of Ni and Cu into self-ordered anodic aluminum oxide membranes. As determined by X-ray diffraction and Transmission Electron Microscopy, the crystalline structure shows fcc cubic symmetry with [111] preferred texture and preferential Ni or Cu lattice depending on the composition. Their magnetic properties such as coercivity and squareness have been determined as a function of composition and geometry in a Vibrating Sample Magnetometer in the temperature range from 10 to 290 K for applied magnetic fields parallel and perpendicular to the nanowires axis. Addition of Cu into the NiCu alloy up to 50% enhances both parallel coercivity and squareness. For the higher Cu content, these properties decrease and the magnetization easy axis becomes oriented perpendicular to the wires. In addition, coercivity and squareness increase by decreasing the diameter of nanowires which is ascribed to the increase of shape anisotropy. The temperature dependent measurements reflect a complex behavior of the magnetic anisotropy as a result of energy contributions with different evolution with temperature.
Spall behavior of cast iron with varying microstructures
Authors: Plume Gifford , Rousseau Carl-Ernst
Published: July 2014

The spall strength of cast iron with varying microstructures has been investigated using plate impact at moderate speed. Stress history measurements were made with manganin stress gauges embedded between the back face of the specimen and a low impedance polycarbonate backing. Five separate cast irons were tested. Four of these consisted of gray cast iron with graphite in flake form, with three classified as Type VII A2 and the fourth containing a bimodal distribution of Types VII A4 and VII D8. The fifth casting consisted of ductile cast iron with graphite in nodular form, classified as Type I, size class 5. The spall strength for the Type VII A2 gray cast irons varied between 40 and 370 MPa, and that of the additional gray cast iron, between 410 and 490 MPa. The spall strength of the ductile cast iron fell within the range of 0.94–1.2 GPa. It is shown that the spall strength is linked to the damage level at the spall plane, where an increased level of tensile stress is required to generate higher levels of damage. Post mortem analysis was performed on the recovered samples, revealing the graphite phase to be the primary factor governing the spall fracture of cast irons, where crack nucleation is directly correlated to the debonding of graphite from the metal matrix. The average length of graphite found within a casting is linked to the material's strength, where strength increases as a function of decreasing length. The morphology and mean free path of graphite precipitates further govern the subsequent coalescence of initiated cracks to form a complete fracture plane. In cases where graphite spacing is large, increased energy level is required to complete the fracture process. A secondary factor governing the spall fracture of cast irons has also been linked to the microstructure of the metal matrix, with pearlite yielding higher spall strengths than free ferrite.
Thermal evolution of defects in undoped zinc oxide grown by pulsed laser deposition
Authors: Wang Zilan , Su Shichen , Ling Francis Chi-Chung , Anwand W. , Wagner A.
Published: July 2014

Undoped ZnO films are grown by pulsed laser deposition on c-plane sapphire with different oxygen pressures. Thermal evolutions of defects in the ZnO films are studied by secondary ion mass spectroscopy (SIMS), Raman spectroscopy, and positron annihilation spectroscopy (PAS), and with the electrical properties characterized by the room temperature Hall measurement. Oxygen deficient defect related Raman lines 560 cm−1 and 584 cm−1 are identified and their origins are discussed. Thermal annealing induces extensive Zn out-diffusion at the ZnO/sapphire interface and leaves out Zn-vacancy in the ZnO film. Two types of Zn-vacancy related defects with different microstructures are identified in the films. One of them dominates in the samples grown without oxygen. Annealing the sample grown without oxygen or growing the samples in oxygen would favor the Zn-vacancy with another microstructure, and this Zn-vacancy defect persists after 1100 °C annealing.
In-line single-mode fiber variable optical attenuator based on electrically addressable microdroplets
Authors: Duduś A. , Blue R. , Zagnoni M. , Stewart G. , Uttamchandani D.
Published: July 2014

We report an in-line, fiber optic, broadband variable optical attenuator employing a side-polished, single-mode optical fiber integrated on a digital microfluidics platform. The system is designed to electrically translate a liquid droplet along the polished surface of an optical fiber using electrowetting forces. This fiber optic device has the advantage of no moving mechanical parts and lends itself to miniaturization. A maximum attenuation of 25 dB has been obtained in the wavelength range between 1520 nm and 1560 nm.
Electrical conduction mechanisms in the transfer characteristics of pentacene thin film transistors
Authors: Lin Yow-Jon , Lin Yu-Cheng
Published: July 2014

In order to understand the electrical conduction mechanisms in the transfer characteristics of pentacene-based organic thin film transistors (OTFTs), an analysis using the temperature-dependent transfer characteristics is presented. The temperature-dependent transfer characteristics exhibit hopping conduction behavior. Compared to the fitting data for the temperature-dependent linear-regime (saturation-regime) transfer characteristics of OTFTs, the fitting data for the temperature-dependent sub-threshold-regime transfer characteristics of OTFTs show that a longer hopping distance and a higher barrier height for hopping result in a higher channel resistance. However, similar hopping conduction behavior is seen in the saturation and linear regions, which demonstrates that the carrier mobility is drain-source voltage-dependent.
Oxygen vacancy tuned Ohmic-Schottky conversion for enhanced performance in β-Ga2O3 solar-blind ultraviolet photodetectors
Authors: Guo D. Y. , Wu Z. P. , An Y. H. , Guo X. C. , Chu X. L. , Sun C. L. , Li L. H. , Li P. G. , Tang W. H.
Published: July 2014

β-Ga2O3 epitaxial thin films were deposited using laser molecular beam epitaxy technique and oxygen atmosphere in situ annealed in order to reduce the oxygen vacancy. Metal/semiconductor/metal structured photodetectors were fabricated using as-grown film and annealed film separately. Au/Ti electrodes were Ohmic contact with the as-grown films and Schottky contact with the annealed films. In compare with the Ohmic-type photodetector, the Schottky-type photodetector takes on lower dark current, higher photoresponse, and shorter switching time, which benefit from Schottky barrier controlling electron transport and the quantity of photogenerated carriers trapped by oxygen vacancy significant decreasing.
Experimental dynamical characterization of five autonomous chaotic oscillators with tunable series resistance
Authors: Minati Ludovico
Published: July 2014

In this paper, an experimental characterization of the dynamical properties of five autonomous chaotic oscillators, based on bipolar-junction transistors and obtained de-novo through a genetic algorithm in a previous study, is presented. In these circuits, a variable resistor connected in series to the DC voltage source acts as control parameter, for a range of which the largest Lyapunov exponent, correlation dimension, approximate entropy, and amplitude variance asymmetry are calculated, alongside bifurcation diagrams and spectrograms. Numerical simulations are compared to experimental measurements. The oscillators can generate a considerable variety of regular and chaotic sine-like and spike-like signals.
Simultaneous impact of neutron irradiation and sputtering on the surface structure of self–damaged ITER–grade tungsten
Authors: Belyaeva A. I. , Savchenko A. A. , Galuza A. A. , Kolenov I. V.
Published: July 2014

Simultaneous effects of neutron irradiation and long–term sputtering on the surface relief of ITER–grade tungsten were studied. The effects of neutron–induced displacement damage have been simulated by irradiation of tungsten target with W6 + ions of 20 MeV energy. Ar+ ions with energy 600 eV were used as imitation of charge exchange atoms in ITER. The surface relief was studied after each sputtering act. The singularity in the WJ–IG surface relief was ascertained experimentally at the first time, which determines the law of roughness extension under sputtering. As follows from the experimental data, the neutron irradiation has not to make a decisive additional contribution in the processes developing under impact of charge exchange atoms only.
Fetal programming in 2-year-old calving heifers: peri-conception and first trimester protein restriction alters fetal growth in a gender-specific manner
Authors: Copping K. J. , Hoare A. , Callaghan M. , McMillen I. C. , Rodgers R. J. , Perry V. E. A.
Published: July 2014

Protein restriction in early bovine gestation affects post-natal reproduction and production traits in progeny. This experiment evaluated the effects of dietary protein restriction during the peri-conception period and first trimester in yearling heifers on conceptus growth and development; this period of dietary intervention being earlier than any previous bovine fetal programming studies. Three-hundred and sixty primiparous 12-month-old Santa Gertrudis heifers were individually fed high [14% crude protein (CP)] or low (7% CP) diets for 60 days before conception. At 23 days post-conception (dpc), each high (HPERI) or low (LPERI) group was again split into high (HPOST) or low (LPOST) protein groups yielding four treatment groups in a 2 × 2 factorial design. From the end of the first trimester of gestation (98dpc), the pregnant heifers were individually fed a 12% CP diet until parturition. Forty-six fetuses were excised at 98dpc. Sixty-four heifers went on to calve. Conceptus development was assessed via transrectal ultrasound from 36dpc, fetal necropsy at 98dpc and live calf measures at term. At 36dpc, HPERI diet increased fetal crown–rump length (CRL) (P < 0.05) and at the 60dpc scan, biparietal diameter (BPD) tended to be increased by HPOST diet (P < 0.1) though the greater effect upon BPD was still the HPERI diet (P < 0.05). At 60dpc, BPD in the male fetus was affected by the peri-conception diet (P < 0.05), while in females, BPD was not different among nutritional groups. These ultrasound measures of fetal growth were validated by measures of the excised fetus at 98dpc. Fetal weight was heavier (P < 0.01) in those whose mothers were fed the HPOST diet than their LPOST counterparts. Males fetuses were heavier than female fetuses (P < 0.001). Fetal CRL was increased by HPERI diet (P < 0.05) and tended to be increased by HPOST diet (P < 0.1). Fetal BPD tended to be increased by HPERI diet (P < 0.1). In males, BPD tended to be increased in those fetuses whose mothers were fed HPERI (P < 0.1). For females, maternal nutrition during PERI or POST did not affect BPD at 98dpc (P > 0.1). At term, no dietary effect on birthweight was observed (P > 0.1) and males were not heavier than females (P > 0.1). These results suggest that maternal protein intake during the peri-conception (–60 to 23dpc) and first trimester (24–98dpc) may influence early conceptus growth and development in the bovine. The long-term effects on offspring metabolism and post-natal development of this dietary intervention are yet to be determined.
A goat is not a sheep: physiological similarities and differences observed in two ruminant species facing a challenge of calcium homeostatic mechanisms
Authors: Wilkens M. R. , Breves G. , Schröder B.
Published: July 2014

As research to investigate calcium (Ca) homeostasis in ruminants is often done using sheep or goats as models for the dairy cow, it was the aim of the present work to give an overview of similarities and differences between small ruminant species observed in recent studies. In both species, ruminal Ca absorption and renal Ca excretion were not affected by dietary Ca supply. But while sheep kept on dietary Ca restriction showed decreased plasma Ca and increased phosphate (P) concentrations, goats were able to compensate for the low Ca availability. This might have been caused by the greater stimulation of vitamin D-dependent intestinal Ca absorption observed in goats. As a response to dietary Ca restriction, sheep had a smaller increase in plasma calcitriol but a greater increase in the circulating concentration of a bone resorption marker. Species differences were also found in respect to Ca and P concentrations in ruminal and abomasal fluids as well as in saliva. We could demonstrate a 2-fold greater salivary P secretion for goats compared with sheep. However, the physiological relation of this finding to Ca homeostasis has not yet been clarified. Fundamental differences in the contribution of gastrointestinal Ca absorption and bone mobilisation to the maintenance of Ca homeostasis were also observed in the peripartal period and when lactating and non-lactating animals of both species were compared.
Structural basis for allosteric cross-talk between the asymmetric nucleotide binding sites of a heterodimeric ABC exporter
Authors: Hohl Michael , Hürlimann Lea M. , Böhm Simon , Schöppe Jendrik , Grütter Markus G. , Bordignon Enrica , Seeger Markus A.
Published: July 2014

Significance

ATP binding cassette (ABC) exporters contain a pair of nucleotide-binding domains (NBDs), which bind and hydrolyze ATP to pump substrates across the membrane. Functional studies suggest that the two ATP binding sites are conformationally coupled. In contrast to other ABC exporters, we show that the asymmetric NBDs of the heterodimeric ABC exporter TM287/288 remain in contact, even in the absence of nucleotides. By comparing the apo state with the adenosine 5′-(β,γ-imido)triphosphate–bound structure of TM287/288, we unravel the structural basis for allosteric coupling between the ATP binding sites. NBD-NBD contacts in the inward-facing transporter warrant cross-communication between the ATP binding sites throughout the transport cycle and are in agreement with functional models of clinically important heterodimeric ABC exporters including CFTR, SUR1, and TAP1/2.
TMEM129 is a Derlin-1 associated ERAD E3 ligase essential for virus-induced degradation of MHC-I
Authors: van den Boomen Dick J. H. , Timms Richard T. , Grice Guinevere L. , Stagg Helen R. , Skødt Karsten , Dougan Gordon , Nathan James A. , Lehner Paul J.
Published: July 2014

Significance

Newly synthesized proteins undergo a strict quality-control checkpoint, and misfolded secretory proteins are targeted across the endoplasmic reticulum membrane back to the cytosol for proteasome degradation. This process requires tagging errant proteins with ubiquitin by an E3 ubiquitin ligase. In a genetic screen we identified TMEM129 as a novel and unusual E3 ligase. TMEM129 is hijacked by the human cytomegalovirus to degrade MHC-I signaling molecules and avert immune recognition of the infected cell. We suggest TMEM129 is an important ligase in the turnover of misfolded secretory proteins within a novel endoplasmic reticulum-associated degradation complex.
Equivariant cohomology, syzygies and orbit structure
Authors: Allday Christopher , Franz Matthias , Puppe Volker
Published: July 2014

Let

X
X

be a “nice” space with an action of a torus 

T
T

. We consider the Atiyah–Bredon sequence of equivariant cohomology modules arising from the filtration of 

X
X

by orbit dimension. We show that a front piece of this sequence is exact if and only if the

H

∗

(
B
T
)

H^{*}(BT)

-module 

H
T

∗

(
X
)

H_T^{*}(X)

is a certain syzygy. Moreover, we express the cohomology of that sequence as an

E
x
t

\mathrm {Ext}

 module involving a suitably defined equivariant homology of 

X
X

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One consequence is that the GKM method for computing equivariant cohomology applies to a Poincaré duality space if and only if the equivariant Poincaré pairing is perfect.
Cordon Bleu serves as a platform at the basal region of microvilli, where it regulates microvillar length through its WH2 domains
Authors: Wayt Jessica , Bretscher Anthony
Published: July 2014

Cordon Bleu (Cobl) is a WH2-containing protein believed to act as an actin nucleator. We show that it has a very specific localization in epithelial cells at the basal region of microvilli, a localization unlikely to be involved in actin nucleation. The protein is localized by a central region between the N-terminal COBL domain and the three C-terminal WH2 domains. Ectopic expression of Cobl shortens apical microvilli, and this requires functional WH2 domains. Proteomic studies reveal that the COBL domain binds several BAR-containing proteins, including SNX9, PACSIN 2/syndapin 2, and ASAP1. ASAP1 is recruited to the base of microvilli by binding the COBL domain through its SH3. We propose that Cobl is localized to the basal region of microvilli both to participate in length regulation and to recruit BAR proteins that associate with the curved membrane found at the microvillar base.
From a single network to a network of networks
Authors: Gao Jianxi , Li Daqing , Havlin Shlomo
Published: July 2014

Network science has attracted much attention in recent years due to its interdisciplinary applications. We witnessed the revolution of network science in 1998 and 1999 started with small-world and scale-free networks having now thousands of high-profile publications, and it seems that since 2010 studies of ‘network of networks’ (NON), sometimes called multilayer networks or multiplex, have attracted more and more attention. The analytic framework for NON yields a novel percolation law for n interdependent networks that shows that percolation theory of single networks studied extensively in physics and mathematics in the last 50 years is a specific limit of the rich and very different general case of n coupled networks. Since then, properties and dynamics of interdependent and interconnected networks have been studied extensively, and scientists are finding many interesting results and discovering many surprising phenomena. Because most natural and engineered systems are composed of multiple subsystems and layers of connectivity, it is important to consider these features in order to improve our understanding of such complex systems. Now the study of NON has become one of the important directions in network science. In this paper, we review recent studies on the new emerging area—NON. Due to the fast growth of this field, there are many definitions of different types of NON, such as interdependent networks, interconnected networks, multilayered networks, multiplex networks and many others. There exist many datasets that can be represented as NON, such as network of different transportation networks including flight networks, railway networks and road networks, network of ecological networks including species interacting networks and food webs, network of biological networks including gene regulation network, metabolic network and protein–protein interacting network, network of social networks and so on. Among them, many interdependent networks including critical infrastructures are embedded in space, introducing spatial constraints. Thus, we also review the progress on study of spatially embedded networks. As a result of spatial constraints, such interdependent networks exhibit extreme vulnerabilities compared with their non-embedded counterparts. Such studies help us to understand, realize and hopefully mitigate the increasing risk in NON.
Transcriptional regulation of the l-lactate permease gene lutP by the LutR repressor of Bacillus subtilis RO-NN-1
Authors: Chiu Kuo-Chin , Lin Chen-Jyun , Shaw Gwo-Chyuan
Published: July 2014

The Bacillus subtilis lutABC operon encodes three iron–sulfur-containing proteins required for l-lactate utilization and involved in biofilm formation. The transcriptional regulator LutR of the GntR family negatively controls lutABC expression. The lutP gene, which is situated immediately upstream of lutR, encodes an l-lactate permease. Here, we show that lutP expression can be strongly induced by l-lactate and is subject to partial catabolite repression by glucose. Disruption of the lutR gene led to a strong derepression of lutP and no further induction by l-lactate, suggesting that the LutR repressor can also negatively control lutP expression. Electrophoretic mobility shift assay revealed a LutR-binding site located downstream of the promoter of lutA or lutP and containing a consensus inverted repeat sequence 5′-TCATC-N1-GATGA-3′. Reporter gene analysis showed that deletion of each LutR-binding site caused a strong derepression of lutA or lutP. These results indicated that these two LutR-binding sites can function as operators in vivo. Moreover, deletion analysis identified a DNA segment upstream of the lutP promoter to be important for lutP expression. In contrast to the truncated LutR of laboratory strains 168 and PY79, the full-length LutR of the undomesticated strain RO-NN-1, and probably many other B. subtilis strains, can directly and negatively regulate lutP transcription. The absence or presence of the N-terminal 21 aa of the full-length LutR, which encompass a small part of the predicted winged helix–turn–helix DNA-binding motif, may probably alter the DNA-binding specificity or affinity of LutR.
Reagent contamination can critically impact sequence-based microbiome analyses
Authors: Salter Susannah J , Cox Michael J , Turek Elena M , Calus Szymon T , Cookson William O , Moffatt Miriam F , Turner Paul , Parkhill Julian , Loman Nick , Walker Alan W
Published: July 2014

The study of microbial communities has been revolutionised in recent years by the widespread adoption of culture independent analytical techniques such as 16S rRNA gene sequencing and metagenomics. One potential confounder of these sequence-based approaches is the presence of contamination in DNA extraction kits and other laboratory reagents. In this study we demonstrate that contaminating DNA is ubiquitous in commonly used DNA extraction kits, varies greatly in composition between different kits and kit batches, and that this contamination critically impacts results obtained from samples containing a low microbial biomass. Contamination impacts both PCR based 16S rRNA gene surveys and shotgun metagenomics. These results suggest that caution should be advised when applying sequence-based techniques to the study of microbiota present in low biomass environments. We provide an extensive list of potential contaminating genera, and guidelines on how to mitigate the effects of contamination. Concurrent sequencing of negative control samples is strongly advised.
Probing the effect of promoters on noise in gene expression using thousands of designed sequences
Authors: Sharon Eilon , van Dijk David , Kalma Yael , Keren Leeat , Manor Ohad , Yakhini Zohar , Segal Eran
Published: July 2014

Genetically identical cells exhibit large variability (noise) in gene expression, with important consequences for cellular function. Although the amount of noise decreases with and is thus partly determined by the mean expression level, the extent to which different promoter sequences can deviate away from this trend is not fully known. Here, we present a high-throughput method for measuring promoter-driven noise for thousands of designed synthetic promoters in parallel. We use it to investigate how promoters encode different noise levels and find that the noise levels of promoters with similar mean expression levels can vary more than one order of magnitude, with nucleosome-disfavoring sequences resulting in lower noise and more transcription factor binding sites resulting in higher noise. We propose a kinetic model of gene expression that takes into account the nonspecific DNA binding and one-dimensional sliding along the DNA, which occurs when transcription factors search for their target sites. We show that this assumption can improve the prediction of the mean-independent component of expression noise for our designed promoter sequences, suggesting that a transcription factor target search may affect gene expression noise. Consistent with our findings in designed promoters, we find that binding-site multiplicity in native promoters is associated with higher expression noise. Overall, our results demonstrate that small changes in promoter DNA sequence can tune noise levels in a manner that is predictable and partly decoupled from effects on the mean expression levels. These insights may assist in designing promoters with desired noise levels.
Adjustment of the UKU Side Effect Rating Scale for adults with intellectual disabilities. A pilot study
Authors: Louise Tveter Anne , Lise Bakken Trine , G. Bramness Jørgen , Ivar Røssberg Jan
Published: July 2014

Purpose

– Patients with intellectual disabilities (ID) and additional psychiatric disorders are often treated with psychotropic medication. However, examinations of side effects among these patients are scarce. The purpose of this pilot study is to examine the most frequently used side effect scale, UKU Side Effect Rating Scale (UKU-SERS), in this patient population.

Design/methodology/approach

– The aim of the present study is to explore whether the UKU-SERS is feasible for patients with ID. The UKU-SERS consists originally of 48 items, measuring side effects of psychotropic medication. In the study, UKU-SERS was used to score a group of 13 adults with ID admitted to a specialised inpatient psychiatric unit. First, an expert panel of seven psychiatrists and five psychiatric nurses independently evaluated the UKU-SERS and decided which items they considered possible to score after observation alone. Second, a total of 26 staff members, based on observation, scored the 13 patients on the ward. These results were used as the basis for recommending items from UKU-SERS to be used. Items scored differently by the two groups were examined more thoroughly.

Findings

– The expert panel and the ward staff agreed on 24 of the original 48 UKU-SERS items. The other 24 items were examined more thoroughly based on clinical meaningfulness. Consequently, 11 more items were included despite disagreement in the scorer groups. As expected, items that are based on observations seem more feasible than items based on the patients’ subjective experiences.

Originality/value

– The revised checklist comprises 35 items and seems applicable for further research and for use in clinical settings for this patient population. It is possible to observe important side effects using the UKU Side Effect Scale, but adjustment of the scale is desirable to make it more appropriate for the specific purpose and target group.