bluuebunny/crossref_metadata_2025 huggingface dataset:
Surgical Treatment of Orbital Blowout Fractures: Complications and Postoperative Care Patterns
Authors: Shew Matthew , Carlisle Michael P. , Lu GuanningNina , Humphrey Clinton , Kriet J.David
Published: August 2016

Orbital fractures are a common result of facial trauma. Sequelae and indications for repair include enophthalmos and/or diplopia from extraocular muscle entrapment. Alloplastic implant placement with careful release of periorbital fat and extraocular muscles can effectively restore extraocular movements, orbital integrity, and anatomic volume. However, rare but devastating complications such as retrobulbar hematoma (RBH) can occur after repair, which pose a risk of permanent vision loss if not addressed emergently. For this reason, some surgeons take the precaution of admitting patients for 24-hour postoperative vision checks, while others do not. The incidence of postoperative RBH has not been previously reported and existing data are limited to case reports. Our aim was to examine national trends in postoperative management and to report the incidence of immediate postoperative complications at our institution following orbital repair. A retrospective assessment of orbital blowout fractures was undertaken to assess immediate postoperative complications including RBH. Only patients treated by a senior surgeon in the Department of Otolaryngology were included in the review. In addition, we surveyed AO North America (AONA) Craniomaxillofacial faculty to assess current trends in postoperative management. There were 80 patients treated surgically for orbital blowout fractures over a 9.5-year period. Nearly all patients were observed overnight (74%) or longer (25%) due to other trauma. Average length of stay was 17 hours for those observed overnight. There was one (1.3%) patient with RBH, who was treated and recovered without sequelae. Results of the survey indicated that a majority (64%) of responders observe postoperative patients overnight. Twenty-nine percent of responders indicated that they send patients home the same day of surgery. Performance of more than 20 orbital repairs annually significantly increased the likelihood that faculty would manage patients on an outpatient basis postoperatively ( p = 0.04). For orbital blowout fractures, the number of immediate postoperative complications at our institution is low. In addition, North American trends in postoperative management of orbital blowout fractures may suggest that selected patients can be managed on an outpatient basis, which would have a positive effect on conservation of diminishing healthcare resources.
Orbitocerebral Impalement: Case Discussion and Management Algorithm
Authors: Crowson Matthew Gordon , Berger Miles , McCarthy Grace C. , Powers David B.
Published: August 2016

Orbitocerebral impalement by inanimate objects is a relatively uncommon event. If orbitocerebral impalement is suspected, management entails prompt referral to a trauma facility with neurosurgical, neuroanesthesiological, craniomaxillofacial, and ophthalmological expertise. The aim of this report is to describe the unique mechanism and perioperative considerations of a remarkable, deep orbitocerebral impalement from a walker brake lever through the orbital roof after a fall from standing. We discuss clinical vignette, evaluation, anesthetic approach, and considerations and review the literature on the epidemiology, pathophysiology, surgical and anesthetic management, and prognosis of this traumatic mechanism. We also offer a management algorithm that aims to streamline management.
Thermal analysis of the in-vessel components of the ITER plasma-position reflectometry
Authors: Quental P. B. , Policarpo H. , Luís R. , Varela P.
Published: August 2016

The ITER plasma position reflectometry system measures the edge electron density profile of the plasma, providing real-time supplementary contribution to the magnetic measurements of the plasma-wall distance. Some of the system components will be in direct sight of the plasma and therefore subject to plasma and stray radiation, which may cause excessive temperatures and stresses. In this work, thermal finite element analysis of the antenna and adjacent waveguides is conducted with ANSYS V17 (ANSYS® Academic Research, Release 17.0, 2016). Results allow the identification of critical temperature points, and solutions are proposed to improve the thermal behavior of the system.
Auger generation as an intrinsic limit to tunneling field-effect transistor performance
Authors: Teherani James T. , Agarwal Sapan , Chern Winston , Solomon Paul M. , Yablonovitch Eli , Antoniadis Dimitri A.
Published: August 2016

Many in the microelectronics field view tunneling field-effect transistors (TFETs) as society's best hope for achieving a >10× power reduction for electronic devices; however, despite a decade of considerable worldwide research, experimental TFET results have significantly underperformed simulations and conventional MOSFETs. To explain the discrepancy between TFET experiments and simulations, we investigate the parasitic leakage current due to Auger generation, an intrinsic mechanism that cannot be mitigated with improved material quality or better device processing. We expose the intrinsic link between the Auger and band-to-band tunneling rates, highlighting the difficulty of increasing one without the other. From this link, we show that Auger generation imposes a fundamental limit on ultimate TFET performance.
Final design of thermal diagnostic system in SPIDER ion source
Authors: Brombin M. , Dalla Palma M. , Pasqualotto R. , Pomaro N.
Published: August 2016

The prototype radio frequency source of the ITER heating neutral beams will be first tested in SPIDER test facility to optimize H− production, cesium dynamics, and overall plasma characteristics. Several diagnostics will allow to fully characterise the beam in terms of uniformity and divergence and the source, besides supporting a safe and controlled operation. In particular, thermal measurements will be used for beam monitoring and system protection. SPIDER will be instrumented with mineral insulated cable thermocouples, both on the grids, on other components of the beam source, and on the rear side of the beam dump water cooled elements. This paper deals with the final design and the technical specification of the thermal sensor diagnostic for SPIDER. In particular the layout of the diagnostic, together with the sensors distribution in the different components, the cables routing and the conditioning and acquisition cubicles are described.
Sub-60 mV/decade switching in 2D negative capacitance field-effect transistors with integrated ferroelectric polymer
Authors: McGuire Felicia A. , Cheng Zhihui , Price Katherine , Franklin Aaron D.
Published: August 2016

There is a rising interest in employing the negative capacitance (NC) effect to achieve sub-60 mV/decade (below the thermal limit) switching in field-effect transistors (FETs). The NC effect, which is an effectual amplification of the applied gate potential, is realized by incorporating a ferroelectric material in series with a dielectric in the gate stack of a FET. One of the leading challenges to such NC-FETs is the variable substrate capacitance exhibited in 3D semiconductor channels (bulk, Fin, or nanowire) that minimizes the extent of sub-60 mV/decade switching. In this work, we demonstrate 2D NC-FETs that combine the NC effect with 2D MoS2 channels to extend the steep switching behavior. Using the ferroelectric polymer, poly(vinylidene difluoride-trifluoroethylene) (P(VDF-TrFE)), these 2D NC-FETs are fabricated by modification of top-gated 2D FETs through the integrated addition of P(VDF-TrFE) into the gate stack. The impact of including an interfacial metal between the ferroelectric and dielectric is studied and shown to be critical. These 2D NC-FETs exhibit a decrease in subthreshold swing from 113 mV/decade down to 11.7 mV/decade at room temperature with sub-60 mV/decade switching occurring over more than 4 decades of current. The P(VDF-TrFE) proves to be an unstable option for a device technology, yet the superb switching behavior observed herein opens the way for further exploration of nanomaterials for extremely low-voltage NC-FETs.
Static electric field enhancement in nanoscale structures
Authors: Lepetit Bruno , Lemoine Didier , Márquez-Mijares Maykel
Published: August 2016

We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.
Hartree potential dependent exchange functional
Authors: Constantin Lucian A. , Fabiano Eduardo , Della Sala Fabio
Published: August 2016

We introduce a novel non-local ingredient for the construction of exchange density functionals: the reduced Hartree parameter, which is invariant under the uniform scaling of the density and represents the exact exchange enhancement factor for one- and two-electron systems. The reduced Hartree parameter is used together with the conventional meta-generalized gradient approximation (meta-GGA) semilocal ingredients (i.e., the electron density, its gradient, and the kinetic energy density) to construct a new generation exchange functional, termed u-meta-GGA. This u-meta-GGA functional is exact for the exchange of any one- and two-electron systems, is size-consistent and non-empirical, satisfies the uniform density scaling relation, and recovers the modified gradient expansion derived from the semiclassical atom theory. For atoms, ions, jellium spheres, and molecules, it shows a good accuracy, being often better than meta-GGA exchange functionals. Our construction validates the use of the reduced Hartree ingredient in exchange-correlation functional development, opening the way to an additional rung in the Jacob’s ladder classification of non-empirical density functionals.
From plane waves to local Gaussians for the simulation of correlated periodic systems
Authors: Booth George H. , Tsatsoulis Theodoros , Chan Garnet Kin-Lic , Grüneis Andreas
Published: August 2016

We present a simple, robust, and black-box approach to the implementation and use of local, periodic, atom-centered Gaussian basis functions within a plane wave code, in a computationally efficient manner. The procedure outlined is based on the representation of the Gaussians within a finite bandwidth by their underlying plane wave coefficients. The core region is handled within the projected augment wave framework, by pseudizing the Gaussian functions within a cutoff radius around each nucleus, smoothing the functions so that they are faithfully represented by a plane wave basis with only moderate kinetic energy cutoff. To mitigate the effects of the basis set superposition error and incompleteness at the mean-field level introduced by the Gaussian basis, we also propose a hybrid approach, whereby the complete occupied space is first converged within a large plane wave basis, and the Gaussian basis used to construct a complementary virtual space for the application of correlated methods. We demonstrate that these pseudized Gaussians yield compact and systematically improvable spaces with an accuracy comparable to their non-pseudized Gaussian counterparts. A key advantage of the described method is its ability to efficiently capture and describe electronic correlation effects of weakly bound and low-dimensional systems, where plane waves are not sufficiently compact or able to be truncated without unphysical artifacts. We investigate the accuracy of the pseudized Gaussians for the water dimer interaction, neon solid, and water adsorption on a LiH surface, at the level of second-order Møller–Plesset perturbation theory.
HNS+ and HSN+ cations: Electronic states, spin-rovibronic spectroscopy with planetary and biological implications
Authors: Trabelsi Tarek , Ben Yaghlane Saida , Al Mogren Muneerah Mogren , Francisco Joseph S. , Hochlaf Majdi
Published: August 2016

Ab initio methods in conjunction with a large basis set are used to compute the potential energy surfaces of the 12 lowest electronic states of the HNS+ and HSN+ isomeric forms. These potentials are used in discussions of the metastability of these cations and plausible mechanisms for the H+/H + SN+/SN, S/S+ + NH+/NH, N/N+ + SH+/SH ion-molecule reactions. Interestingly, the low rovibrational levels of HSN+(12A″) and HNS+(12A″) electronically excited ions are predicted to be long-lived. Both ions are suggested to be a suitable candidate for light-sensitive NO⋅ donor in vivo and as a possible marker for the detection of intermediates in nitrites + H2S reactions at the cellular level. The full spin rovibronic levels of HNS+ are presented, which may assist in the experimental identification of HNS+ and HSN+ ions and in elucidating their roles in astrophysical and biological media.
Direct bandgap cross-over point of Ge1-ySny grown on Si estimated through temperature-dependent photoluminescence studies
Authors: Harris Thomas R. , Ryu Mee-Yi , Yeo Yung Kee , Wang Buguo , Senaratne C. L. , Kouvetakis John
Published: August 2016

Epitaxial Ge1-ySny (y = 0%–7.5%) alloys grown on either Si or Ge-buffered Si substrates by chemical vapor deposition were studied as a function of Sn content using temperature-dependent photoluminescence (PL). PL emission peaks from both the direct bandgap (Γ-valley) and the indirect bandgap (L-valley) to the valence band (denoted by ED and EID, respectively) were clearly observed at 125 and 175 K for most Ge1-ySny samples studied. At 300 K, however, all of the samples exhibited dominant ED emission with either very weak or no measureable EID emission. At 10 K, ED is dominant only for Ge1-ySny with y > 0.052. From the PL spectra taken at 125 and 175 K, the unstrained indirect and direct bandgap energies were calculated and are plotted as a function of Sn concentration, the results of which show that the indirect-to-direct bandgap transition occurs at ∼6.7% Sn. It is believed that the true indirect-to-direct bandgap cross-over of unstrained Ge1-ySny might also take place at about the same Sn content at room temperature. This observation suggests that these Ge1-ySny alloys could become very promising direct bandgap semiconductor materials, which will be very useful for the development of various new novel Si- and Ge-based infrared optoelectronic devices that can be fully integrated with current technology on a single Si chip.
Geometric integrator for simulations in the canonical ensemble
Authors: Tapias Diego , Sanders David P. , Bravetti Alessandro
Published: August 2016

We introduce a geometric integrator for molecular dynamics simulations of physical systems in the canonical ensemble that preserves the invariant distribution in equations arising from the density dynamics algorithm, with any possible type of thermostat. Our integrator thus constitutes a unified framework that allows the study and comparison of different thermostats and of their influence on the equilibrium and non-equilibrium (thermo-)dynamic properties of a system. To show the validity and the generality of the integrator, we implement it with a second-order, time-reversible method and apply it to the simulation of a Lennard-Jones system with three different thermostats, obtaining good conservation of the geometrical properties and recovering the expected thermodynamic results. Moreover, to show the advantage of our geometric integrator over a non-geometric one, we compare the results with those obtained by using the non-geometric Gear integrator, which is frequently used to perform simulations in the canonical ensemble. The non-geometric integrator induces a drift in the invariant quantity, while our integrator has no such drift, thus ensuring that the system is effectively sampling the correct ensemble.
Maximising electro-mechanical response by minimising grain-scale strain heterogeneity in phase-change actuator ceramics
Authors: Oddershede Jette , Hossain Mohammad Jahangir , Daniels John E.
Published: August 2016

Phase-change actuator ceramics directly couple electrical and mechanical energies through an electric-field-induced phase transformation. These materials are promising for the replacement of the most common electro-mechanical ceramic, lead zirconate titanate, which has environmental concerns. Here, we show that by compositional modification, we reduce the grain-scale heterogeneity of the electro-mechanical response by 40%. In the materials investigated, this leads to an increase in the achievable electric-field-induced strain of the bulk ceramic of 45%. Compositions of (100–x)Bi0.5Na0.5TiO3–(x)BaTiO3, which initially possess a pseudo-cubic symmetry, can be tuned to undergo phase transformations to combined lower symmetry phases, thus decreasing the anisotropy of the transformation strain. Further, modelling of transformation strains of individual grains shows that minimum grain-scale strain heterogeneity can be achieved by precise control of the lattice distortions and orientation distributions of the induced phases. The current results can be used to guide the design of next generation high-strain electro-mechanical ceramic actuator materials.
Implementation of the new multichannel X-mode edge density profile reflectometer for the ICRF antenna on ASDEX Upgrade
Authors: Aguiam D. E. , Silva A. , Bobkov V. , Carvalho P. J. , Carvalho P. F. , Cavazzana R. , Conway G. D. , D’Arcangelo O. , Fattorini L. , Faugel H. , Fernandes A. , Fünfgelder H. , Gonçalves B. , Guimarais L. , De Masi G. , Meneses L. , Noterdaeme J. M. , Pereira R. C. , Rocchi G. , Santos J. M. , Tuccillo A. A. , Tudisco O. ,   ASDEX Upgrade Team
Published: August 2016

A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of the Ion Cyclotron Range of Frequencies (ICRF) antenna. The design of the new three-strap ICRF antenna integrates ten pairs (sending and receiving) of microwave reflectometry antennas. The multichannel reflectometer can use three of these to measure the edge electron density profiles up to 2 × 1019 m−3, at different poloidal locations, allowing the direct study of the local plasma layers in front of the ICRF antenna. ICRF power coupling, operational effects, and poloidal variations of the plasma density profile can be consistently studied for the first time. In this work the diagnostic hardware architecture is described and the obtained density profile measurements were used to track outer radial plasma position and plasma shape.
Stress-induced large anisotropy field modulation in Ni films deposited on a flexible substrate
Authors: Asai R. , Ota S. , Namazu T. , Takenobu T. , Koyama T. , Chiba D.
Published: August 2016

A tensile strain on the order of a few percent was created in Ni thin films deposited on a flexible polyethylene naphthalate substrate, and the strain-induced change in the magnetic anisotropy was investigated. The magnetic easy axis was reversibly switched by 90° by the application of the stress. The easy axis was orthogonal to the applied stress. The in-plane saturation magnetic field or the uniaxial magnetic anisotropy energy changed linearly in reaction to the applied tensile strain up to a strain of 2.3%. Moreover, a large difference in the saturation magnetic field up to ∼0.3 T, which corresponds to a change in the magnetic anisotropy energy of ∼7 × 104 J/m3, was realized. The effective magnetoelastic coupling constant was almost independent of the thickness of Ni.
Threshold for permanent refractive index change in crystalline silicon by femtosecond laser irradiation
Authors: Bachman D. , Chen Z. , Fedosejevs R. , Tsui Y. Y. , Van V.
Published: August 2016

An optical damage threshold for crystalline silicon from single femtosecond laser pulses was determined by detecting a permanent change in the refractive index of the material. This index change could be detected with unprecedented sensitivity by measuring the resonant wavelength shift of silicon integrated optics microring resonators irradiated with femtosecond laser pulses at 400 nm and 800 nm wavelengths. The threshold for permanent index change at 400 nm wavelength was determined to be 0.053 ± 0.007 J/cm2, which agrees with previously reported threshold values for femtosecond laser modification of crystalline silicon. However, the threshold for index change at 800 nm wavelength was found to be 0.044 ± 0.005 J/cm2, which is five times lower than the previously reported threshold values for visual change on the silicon surface. The discrepancy is attributed to possible modification of the crystallinity of silicon below the melting temperature that has not been detected before.
Study of the effect of loop inductance on the RF transmission line to cavity coupling coefficient
Authors: Lal Shankar , Pant K. K.
Published: August 2016

Coupling of RF power is an important aspect in the design and development of RF accelerating structures. RF power coupling employing coupler loops has the advantage of tunability of β, the transmission line to cavity coupling coefficient. Analytical expressions available in literature for determination of size of the coupler loop using Faraday’s law of induction show reasonably good agreement with experimentally measured values of β below critical coupling (β ≤ 1) but show large deviation with experimentally measured values and predictions by simulations for higher values of β. In actual accelerator application, many RF cavities need to be over-coupled with β > 1 for reasons of beam loading compensation, reduction of cavity filling time, etc. This paper discusses a modified analytical formulation by including the effect of loop inductance in the determination of loop size for any desired coupling coefficient. The analytical formulation shows good agreement with 3D simulations and with experimentally measured values. It has been successfully qualified by the design and development of power coupler loops for two 476 MHz pre-buncher RF cavities, which have successfully been conditioned at rated power levels using these coupler loops.
Current transport mechanisms in mercury cadmium telluride diode
Authors: Gopal Vishnu , Li Qing , He Jiale , He Kai , Lin Chun , Hu Weida
Published: August 2016

This paper reports the results of modelling of the current-voltage characteristics (I-V) of a planar mid-wave Mercury Cadmium Telluride photodiode in a gate controlled diode experiment. It is reported that the diode exhibits nearly ideal I-V characteristics under the optimum surface potential leading to the minimal surface leakage current. Deviations from the optimum surface potential lead to non ideal I–V characteristics, indicating a strong relationship between the ideality factor of the diode with its surface leakage current. Diode's I–V characteristics have been modelled over a range of gate voltages from −9 V to −2 V. This range of gate voltages includes accumulation, flat band, and depletion and inversion conditions below the gate structure of the diode. It is shown that the I–V characteristics of the diode can be very well described by (i) thermal diffusion current, (ii) ohmic shunt current, (iii) photo-current due to background illumination, and (iv) excess current that grows by the process of avalanche multiplication in the gate voltage range from −3 V to −5 V that corresponds to the optimum surface potential. Outside the optimum gate voltage range, the origin of the excess current of the diode is associated with its high surface leakage currents. It is reported that the ohmic shunt current model applies to small surface leakage currents. The higher surface leakage currents exhibit a nonlinear shunt behaviour. It is also shown that the observed zero-bias dynamic resistance of the diode over the entire gate voltage range is the sum of ohmic shunt resistance and estimated zero-bias dynamic resistance of the diode from its thermal saturation current.
Waveform-preserved unidirectional acoustic transmission based on impedance-matched acoustic metasurface and phononic crystal
Authors: Song Ai-Ling , Chen Tian-Ning , Wang Xiao-Peng , Wan Le-Le
Published: August 2016

The waveform distortion happens in most of the unidirectional acoustic transmission (UAT) devices proposed before. In this paper, a novel type of waveform-preserved UAT device composed of an impedance-matched acoustic metasurface (AMS) and a phononic crystal (PC) structure is proposed and numerically investigated. The acoustic pressure field distributions and transmittance are calculated by using the finite element method. The subwavelength AMS that can modulate the wavefront of the transmitted wave at will is designed and the band structure of the PC structure is calculated and analyzed. The sound pressure field distributions demonstrate that the unidirectional acoustic transmission can be realized by the proposed UAT device without changing the waveforms of the output waves, which is the distinctive feature compared with the previous UAT devices. The physical mechanism of the unidirectional acoustic transmission is discussed by analyzing the refraction angle changes and partial band gap map. The calculated transmission spectra show that the UAT device is valid within a relatively broad frequency range. The simulation results agree well with the theoretical predictions. The proposed UAT device provides a good reference for designing waveform-preserved UAT devices and has potential applications in many fields, such as medical ultrasound, acoustic rectifiers, and noise insulation.
Magnetic invisibility of the magnetically coated type-II superconductor in partially penetrated state
Authors: Peña-Roche J. , Genenko Y. A. , Badía-Majós A.
Published: August 2016

The magnetic behavior of a cylindrical paramagnet/superconductor heterostructure has been studied by numerical simulations. Relying on the variational statement of the critical state model, our results show that magnetic invisibility is compatible with the partial penetration regime in the superconductor. This result accomplishes previous analytic studies that proved a possible perfect undetectability for the full penetration of magnetic flux. For a given geometry, invisibility may be realized only at a certain magnitude of the applied field. Such value decreases with increasing permeability of the magnetic sheath and eventually collapses to zero. This establishes a condition for obtaining realizable invisibility that extends previous expectations relying either on the full penetration ansatz or on perfect diamagnetism.
Epitaxial growth and magnetic properties of NixFe4-xN (x = 0, 1, 3, and 4) films on SrTiO3(001) substrates
Authors: Takata Fumiya , Ito Keita , Higashikozono Soma , Gushi Toshiki , Toko Kaoru , Suemasu Takashi
Published: August 2016

The 20–60 nm-thick epitaxial NixFe4-xN (x = 0, 1, 3, and 4) films were successfully fabricated on SrTiO3(001) single-crystal substrates by alternating the substrate temperature (Tsub), and their crystalline qualities and magnetic properties were investigated. It was found that the crystal orientation and the degree of order of N site were improved with the increase of Tsub for x = 1 and 3. The lattice constant and saturation magnetization decreased as the Ni content increased. This tendency was in good agreement with first-principle calculation. Curie temperature of the Ni3FeN film was estimated to be 266 K from the temperature dependence of magnetization. The Ni4N film was not ferromagnetic but paramagnetic due to its low degree of order of N site.
Fabrication of quantum dots in undoped Si/Si0.8Ge0.2 heterostructures using a single metal-gate layer
Authors: Lu T. M. , Gamble J. K. , Muller R. P. , Nielsen E. , Bethke D. , Ten Eyck G. A. , Pluym T. , Wendt J. R. , Dominguez J. , Lilly M. P. , Carroll M. S. , Wanke M. C.
Published: August 2016

Enhancement-mode Si/SiGe electron quantum dots have been pursued extensively by many groups for their potential in quantum computing. Most of the reported dot designs utilize multiple metal-gate layers and use Si/SiGe heterostructures with Ge concentration close to 30%. Here, we report the fabrication and low-temperature characterization of quantum dots in the Si/Si0.8Ge0.2 heterostructures using only one metal-gate layer. We find that the threshold voltage of a channel narrower than 1 μm increases as the width decreases. The higher threshold can be attributed to the combination of quantum confinement and disorder. We also find that the lower Ge ratio used here leads to a narrower operational gate bias range. The higher threshold combined with the limited gate bias range constrains the device design of lithographic quantum dots. We incorporate such considerations in our device design and demonstrate a quantum dot that can be tuned from a single dot to a double dot. The device uses only a single metal-gate layer, greatly simplifying device design and fabrication.
Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP
Authors: Lamichhane Tej N. , Taufour Valentin , Masters Morgan W. , Parker David S. , Kaluarachchi Udhara S. , Thimmaiah Srinivasa , Bud'ko Sergey L. , Canfield Paul C.
Published: August 2016

ZrMnP and HfMnP single crystals are grown by a self-flux growth technique, and structural as well as temperature dependent magnetic and transport properties are studied. Both compounds have an orthorhombic crystal structure. ZrMnP and HfMnP are ferromagnetic with Curie temperatures around 370 K and 320 K, respectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined to be 1.9 μB/f.u. and 2.1 μB/f.u., respectively, at 50 K. The magnetocaloric effect of ZrMnP in terms of entropy change (ΔS) is estimated to be −6.7 kJ m−3 K−1 around 369 K. The easy axis of magnetization is [100] for both compounds, with a small anisotropy relative to the [010] axis. At 50 K, the anisotropy field along the [001] axis is ∼4.6 T for ZrMnP and ∼10 T for HfMnP. Such large magnetic anisotropy is remarkable considering the absence of rare-earth elements in these compounds. The first principle calculation correctly predicts the magnetization and hard axis orientation for both compounds, and predicts the experimental HfMnP anisotropy field within 25%. More importantly, our calculations suggest that the large magnetic anisotropy comes primarily from the Mn atoms, suggesting that similarly large anisotropies may be found in other 3d transition metal compounds.
Initial nitride formation during plasma-nitridation of cobalt surfaces
Authors: Mattson E. C. , Michalak D. J. , Cabrera W. , Veyan J. F. , Chabal Y. J.
Published: August 2016

Nitridation of metal surfaces is of central importance in microelectronics and spintronics due to the excellent mechanical, thermal, and electrical properties of refractory nitrides. Here, we examine the chemical and structural modification of cobalt surfaces upon nitrogen plasma treatment, using in situ spectroscopic methods, as a method for synthesis of cobalt nitride thin films. We find that nitrogen is incorporated below the surface and forms an ultrathin film of CoN at temperatures as low as 50 °C. In addition, we observe the incorporation of oxygen and NO+ within the surface region. The nitrided cobalt surfaces are fully passivated by N, O, and NO+. These results provide a route for incorporation of cobalt nitride into a wide range applications.
Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels
Authors: Hu Chong , Sun Han , Liu Zhengzhi , Chen Yin , Chen Yangfan , Wu Hongkai , Ren Kangning
Published: August 2016

The diffusion of molecules such as nutrients and oxygen through densely packed cells is impeded by blockage and consumption by cells, resulting in a limited depth of penetration. This has been a major hurdle to a bulk (3-D) culture. Great efforts have been made to develop methods for generating branched microchannels inside hydrogels to support mass exchange inside a bulk culture. These previous attempts faced a common obstacle: researchers tried to fabricate microchannels with gels already loaded with cells, but the fabrication procedures are often harmful to the embedded cells. Herein, we present a universal strategy to create microchannels in different types of hydrogels, which effectively avoids cell damage. This strategy is based on a freestanding alginate 3-D microvascular network prepared by in-situ generation of copper ions from a sacrificial copper template. This alginate network could be used as implants to create microchannels inside different types of hydrogels. This approach effectively addresses the issue of cell damage during microfabrication and made it possible to create microchannels inside different types of gels. The microvascular network produced with this method is (1) strong enough to allow handling, (2) biocompatible to allow cell culturing, and (3) appropriately permeable to allow diffusion of small molecules, while sufficiently dense to prevent blocking of channels when embedded in different types of gels. In addition, composite microtubules could be prepared by simply pre-loading other materials, e.g., particles and large biomolecules, in the hydrogel. Compared with other potential strategies to fabricate freestanding gel channel networks, our method is more rapid, low-cost and scalable due to parallel processing using an industrially mass-producible template. We demonstrated the use of such vascular networks in creating microchannels in different hydrogels and composite gels, as well as with a cell culture in a nutrition gradient based on microfluidic diffusion. In this way, the freestanding hydrogel vascular network we produced is a universal functional unit that can be embedded in different types of hydrogel; users will be able to adopt this strategy to achieve vascular mass exchange in the bulk culture without changing their current protocol. The method is readily implementable to applications in vascular tissue regeneration, drug discovery, 3-D culture, etc.
Mixing injector enables time-resolved crystallography with high hit rate at X-ray free electron lasers
Authors: Calvey George D. , Katz Andrea M. , Schaffer Chris B. , Pollack Lois
Published: August 2016

Knowledge of protein structure provides essential insight into function, enhancing our understanding of diseases and enabling new treatment development. X-ray crystallography has been used to solve the structures of more than 100 000 proteins; however, the vast majority represent long-lived states that do not capture the functional motions of these molecular machines. Reactions triggered by the addition of a ligand can be the most challenging to detect with crystallography because of the difficulty of synchronizing reactions to create detectable quantities of transient states. The development of X-ray free electron lasers (XFELs) and serial femtosecond crystallography (SFX) enables new approaches for solving protein structures following the rapid diffusion of ligands into micron sized protein crystals. Conformational changes occurring on millisecond timescales can be detected and time-resolved. Here, we describe a new XFEL injector which incorporates a microfluidic mixer to rapidly combine reactant and sample milliseconds before the sample reaches the X-ray beam. The mixing injector consists of bonded, concentric glass capillaries. The fabrication process, employing custom laser cut centering spacers and UV curable epoxy, ensures precise alignment of capillaries for repeatable, centered sample flow and dependable mixing. Crystal delivery capillaries are 50 or 75 μm in diameter and can contain an integrated filter depending on the demands of the experiment. Reaction times can be varied from submillisecond to several hundred milliseconds. The injector features rapid and uniform mixing, low sample dilution, and high hit rates. It is fully compatible with existing SFX beamlines.
Work function of bulk-insulating topological insulator Bi2–xSbxTe3–ySey
Authors: Takane Daichi , Souma Seigo , Sato Takafumi , Takahashi Takashi , Segawa Kouji , Ando Yoichi
Published: August 2016

Recent discovery of bulk insulating topological insulator (TI) Bi2–xSbxTe3–ySey paved a pathway toward practical device application of TIs. For realizing TI-based devices, it is necessary to contact TIs with a metal. Since the band-bending at the interface dominates the character of devices, knowledge of TIs' work function is of essential importance. We have determined the compositional dependence of the work function in Bi2–xSbxTe3–ySey by high-resolution photoemission spectroscopy. The obtained work-function values (4.95–5.20 eV) track the energy shift of the surface chemical potential seen by angle-resolved photoemission spectroscopy. The present result serves as a useful guide for developing TI-based electronic devices.
Numerical investigation on the performance of an automotive thermoelectric generator integrated with a three-way catalytic converter
Authors: Yuan Xiaohong , Bai Wanrong , Deng Yadong , Su Chuqi , Liu Xun , Liu Chunhua , Gu Ban , Wang Yiping
Published: August 2016

The automotive exhaust-based thermoelectric generator integrated with a three-way catalytic converter (TWC) can convert the thermal energy of exhaust gas into an electric energy, and solve the compatibility issues with an exhaust system. More power can be generated when the temperature of heat exchanger is higher. However, the performances of TWC are also affected by the temperature of the heat exchanger. To get more power generation and reduce the impact on the TWC, three heat exchangers with different section shapes were simulated and corresponding surface temperature and back-pressure were compared. Then three kinds of fins were employed in heat exchangers to figure out the effects. Finally, the results showed that the section shape had no obvious effect on the distribution of temperature and pressure in heat exchangers, but the arrangement of the fins inside the heat exchanger had a heavy impact on the performance of the heat exchanger. According to the simulation results, the heat exchanger in which the direction of fins was skewed to the streamwise could get higher temperature and output power at 192.96 W.
Maintaining bucks over 35 days after a male effect improves pregnancy rate in goats
Authors: Araya J. , Bedos M. , Duarte G. , Hernández H. , Keller M. , Chemineau P. , Delgadillo J. A.
Published: August 2016

The ovulation can be induced by the introduction of a male among a group of anovulatory goats, a phenomenon called the ‘male effect’. The objective of this study was to determine whether maintaining bucks over 35 days after the initial introduction of males, improves pregnancy rate in goats. We used sexually active bucks, which were joined (n = 2 each) with three groups of goats (n = 30 each): (i) males remained with females for 15 days (Control group); (ii) males remained with females for 35 days (same buck group); (iii) males were removed at Day 23 and replaced by other males, which were not familiar to the females and which remained with females until Day 35 (new buck group). Percentage of goats ovulating did not differ among groups at Day 19 (≥87%; P = 0.12). Pregnancy rates at Day 35 did not differ between groups (≥70%; P = 0.90). At Day 55, pregnancy rates were similar in the same and new buck groups (96%; P = 1.0), but were higher than that of the Control group (73%; P < 0.05). Therefore, maintaining bucks over 35 days after the onset of the male effect improved pregnancy rate more than 20 points compared with females that remained with the same bucks for 15 days only.
The effect of weight and age on pregnancy rates in Brahman heifers in northern Australia
Authors: Schatz T. J. , Hearnden M. N.
Published: August 2016

The performance of Brahman heifers at their first mating as yearlings (4-year groups of ~100 per year) grazing on improved pasture in the Douglas Daly region and as 2 year olds (3-year groups of ~100 per year) grazing on native pasture in the Victoria River District was studied. The relationships between pre-mating weight and pregnancy rate were established for Brahman heifers mated as yearlings on improved pasture, and as 2 year olds on native pasture with pre-mating weights recorded in late October/early November (before the wet season starts) and in late December (just before the start of mating). These relationships were found to be different indicating that there is an interaction between age and weight that modifies the effect of weight. The relationships were used to model pregnancy rates that are likely to result from different pre-mating weights for these three scenarios. These estimates can be used to identify target mating weights for different situations, and to predict the pregnancy rates for groups of heifers, which will be useful in budgeting and assessing the profitability of different management strategies.
Indefiniteness and specificity marking in Catalan Sign Language (LSC)
Authors: Barberà Gemma
Published: August 2016

Bringing together the areas of sign language semantics-pragmatics interface and discourse reference, this article offers a description of how indefiniteness and (non‑)specificity is encoded in Catalan Sign Language (LSC). By using a combined methodology of corpus data and grammatical tests, the present study shows that the encoding of indefiniteness and specificity in LSC is achieved by three main means, namely lexical signs, the use of nonmanuals, and the use of signing space. The basic primitives required to analyze specificity in LSC comprise wide scope, epistemicity, and partitivity. This article proposes an analysis of the use of signing space in contributing meaning and provides insights into the characterization of the abstract import of signing space.
At the crossroads of autophagy and infection: Noncanonical roles for ATG proteins in viral replication
Authors: Solvik Tina , Debnath Jayanta
Published: August 2016

Autophagy-related (ATG) proteins have increasingly demonstrated functions other than cellular self-eating. In this issue, Mauthe et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201602046) conduct an unbiased RNA interference screen of the ATG proteome to reveal numerous noncanonical roles for ATG proteins during viral infection.
Notch activation drives adipocyte dedifferentiation and tumorigenic transformation in mice
Authors: Bi Pengpeng , Yue Feng , Karki Anju , Castro Beatriz , Wirbisky Sara E. , Wang Chao , Durkes Abigail , Elzey Bennett D. , Andrisani Ourania M. , Bidwell Christopher A. , Freeman Jennifer L. , Konieczny Stephen F. , Kuang Shihuan
Published: August 2016

Liposarcomas (LPSs) are the most common soft-tissue cancer. Because of the lack of animal models, the cellular origin and molecular regulation of LPS remain unclear. Here, we report that mice with adipocyte-specific activation of Notch signaling (Ad/N1ICD) develop LPS with complete penetrance. Lineage tracing confirms the adipocyte origin of Ad/N1ICD LPS. The Ad/N1ICD LPS resembles human dedifferentiated LPS in histological appearance, anatomical localization, and gene expression signature. Before transformation, Ad/N1ICD adipocytes undergo dedifferentiation that leads to lipodystrophy and metabolic dysfunction. Although concomitant Pten deletion normalizes the glucose metabolism of Ad/N1ICD mice, it dramatically accelerates the LPS prognosis and malignancy. Transcriptomes and lipidomics analyses indicate that Notch activation suppresses lipid metabolism pathways that supply ligands to Pparγ, the master regulator of adipocyte homeostasis. Accordingly, synthetic Pparγ ligand supplementation induces redifferentiation of Ad/N1ICD adipocytes and tumor cells, and prevents LPS development in Ad/N1ICD mice. Importantly, the Notch target HES1 is abundantly expressed in human LPS, and Notch inhibition suppresses the growth of human dedifferentiated LPS xenografts. Collectively, ectopic Notch activation is sufficient to induce dedifferentiation and tumorigenic transformation of mature adipocytes in mouse.
Deletion of Slam locus in mice reveals inhibitory role of SLAM family in NK cell responses regulated by cytokines and LFA-1
Authors: Guo Huaijian , Cranert Stacey A. , Lu Yan , Zhong Ming-Chao , Zhang Shaohua , Chen Jun , Li Rui , Mahl Sarah E. , Wu Ning , Davidson Dominique , Waggoner Stephen N. , Veillette André
Published: August 2016

Signaling lymphocytic activation molecule (SLAM) family receptors (SFRs) can mediate either activating or inhibitory effects during natural killer cell (NK cell) activation. In this study, we addressed the global role, regulation, and mechanism of action of the SLAM family in NK cells by analyzing a mouse lacking the entire ∼400-kilobase Slam locus, which encodes all six SFRs and CD48, the ligand of SFR 2B4. This mouse displayed enhanced NK cell activation responses toward hematopoietic target cells. Analyses of mice lacking individual SFRs showed that the inhibitory function of the Slam locus was due solely to 2B4 and was not influenced positively or negatively by other SFRs. Differences in NK cell responses between recognition of targets expressing or lacking ligands for SFRs were enhanced by IL-12 but suppressed by type I interferon. Cytokines also changed the levels of SLAM-associated protein adaptors, which prevent the inhibitory function of SFRs. The enhanced activation responses of SFR-deficient NK cells were dependent on integrin LFA-1 but not on DNAM-1 or NKG2D. SFR-mediated inhibition prevented the generation of activated forms of LFA-1. Hence, the Slam locus has an overall inhibitory role during NK cell activation that is solely dependent on 2B4. This effect is influenced by cytokines and leads to suppression of LFA-1 activity.