bluuebunny/crossref_metadata_2025 huggingface dataset:
Dome C ultracarbonaceous Antarctic micrometeorites
Authors: Dartois E. , Engrand C. , Duprat J. , Godard M. , Charon E. , Delauche L. , Sandt C. , Borondics F.
Published: January 2018

Context.UltraCarbonaceous Antarctic MicroMeteorites (UCAMMs) represent a small fraction of interplanetary dust particles reaching the Earth’s surface and contain large amounts of an organic component not found elsewhere. They are most probably sampling a contribution from the outer regions of the solar system to the local interplanetary dust particle (IDP) flux.

Aims.We characterize UCAMMs composition focusing on the organic matter, and compare the results to the insoluble organic matter (IOM) from primitive meteorites, IDPs, and the Earth.

Methods.We acquired synchrotron infrared microspectroscopy (μFTIR) andμRaman spectra of eight UCAMMs from the Concordia/CSNSM collection, as well as N/C atomic ratios determined with an electron microprobe.

Results.The spectra are dominated by an organic component with a low aliphatic CH versus aromatic C=C ratio, and a higher nitrogen fraction and lower oxygen fraction compared to carbonaceous chondrites and IDPs. The UCAMMs carbonyl absorption band is in agreement with a ketone or aldehyde functional group. Some of the IR and Raman spectra show a C≡N band corresponding to a nitrile. The absorption band profile from 1400 to 1100 cm-1is compatible with the presence of C-N bondings in the carbonaceous network, and is spectrally different from that reported in meteorite IOM. We confirm that the silicate-to-carbon content in UCAMMs is well below that reported in IDPs and meteorites. Together with the high nitrogen abundance relative to carbon building the organic matter matrix, the most likely scenario for the formation of UCAMMs occurs via physicochemical mechanisms taking place in a cold nitrogen rich environment, like the surface of icy parent bodies in the outer solar system. The composition of UCAMMs provides an additional hint of the presence of a heliocentric positive gradient in the C/Si and N/C abundance ratios in the solar system protoplanetary disc evolution.
Vertical strain partitioning in hot Variscan crust: Syn-convergence escape of the Pyrenees in the Iberian-Armorican syntax
Authors: Cochelin Bryan , Chardon Dominique , Denèle Yoann , Gumiaux Charles , Le Bayon Benjamin
Published: January 2018

A new structural map of the Paleozoic crust of the Pyrenees based on an extensive compilation and new kinematic data allows for the evaluation of the mechanical coupling between the upper and lower crust of the abnormally hot foreland of the Variscan orogen of SW Europe. We document partitioning between coeval lower crustal lateral flow and upper crustal thickening between 310 and 290 Ma under an overall dextral transpressive regime. Partitioning also involved syn-convergence transtensional gneiss domes emplacement during this period. Late orogen-normal shortening of the domes and strain localization in steep crustal-scale transpressive shear zones reflects increasing coupling between the lower crust and the upper crust. The combination of dextral transpression and eastward flow in the Pyrenees results from the shortening and lateral escape of a hot buoyant crust along the inner northern limb of the closing Cantabrian orocline at the core of the Iberian-Armorican arc between ca. 305 and 295 Ma. Delamination or thermal erosion of the lithosphere enhanced orocline closure and explains (1) the switch from crust- to mantle-derived magmatism in the Iberian-Armorican arc and (2) the abnormally hot and soft character of the Pyrenean crust that escaped the closing syntax.
An unbalanced optimal transport splitting scheme for general advection-reaction-diffusion problems
Authors: Gallouët Thomas , Laborde Maxime , Monsaingeon Léonard
Published: January 2018

In this paper, we show that unbalanced optimal transport provides a convenient framework to handle reaction and diffusion processes in a unified metric setting. We use a constructive method, alternating minimizing movements for the Wasserstein distance and for the Fisher-Rao distance, and prove existence of weak solutions for general scalar reaction-diffusion-advection equations. We extend the approach to systems of multiple interacting species, and also consider an application to a very degenerate diffusion problem involving a Gamma-limit. Moreover, some numerical simulations are included.
Effect of bottom sediments on the nutrient and metal concentration in macrophytes of river-lake systems
Authors: Kuriata-Potasznik Angela , Szymczyk Sławomir , Pilejczyk Dorota
Published: January 2018

Water bodies of river-lake systems can act as barriers in the movement of nutrients and toxic heavy metals outside their water catchment area. These components can be suspended in the water column, deposited in bottom sediments or bioaccumulated by the vegetation in the water body. A constant exchange of substances takes place between bottom sediments and macrophytes. The composition of bottom sediments and their distribution affects the intensity of nutrients and metals assimilation by macrophytes in the river-lake systems. The aim of research was to analyse the effect of bottom sediments on the nutrients and metal content in macrophytes. It was demonstrated that tissues of plants anchored in sediments that were more abundant in nutrients had higher contents of biogenic components and heavy metals. The properties of bottom sediments, mainly their granulometric composition, but also organic matter content and pH, determine the content of biogenes and heavy metals in macrophytes to a significant extent. On the other hand, it was demonstrated that aquatic plants could affect the grain size in the sediments. Macrophytes and sediments of river-lake systems play a very important role in reducing the transport of nutrients outside the area of the system, through capturing and incorporating them into the tissues of aquatic plants.
Distal Spinal Muscular Atrophy: An Overlooked Etiology of Weaning Failure in Children with Respiratory Insufficiency
Authors: Eghbalkhah Asgar , Kamrani Kamyar , Khosroshahi Nahid , Yousefimanesh Hossein , Eskandarizadeh Zahra , Habibi Zoham Mojdeh
Published: January 2018

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive neuromuscular disorder that involves the anterior horn motor neurons. It is a disease with a poor prognosis presenting with progressive distal motor weakness and respiratory insufficiency from diaphragmatic paralysis followed by distal muscle weakness before 6 months of age. With the intent to spread the awareness of this rare and life-threatening disease, we report a 2.5-month-old female infant with a subsequent diagnosis of SMARD1, who was admitted in our pediatric intensive care unit with chief complaint of progressive respiratory distress and poor feeding.
A 5-Year Follow-Up of Triple-Seronegative Myasthenia Gravis Successfully Treated with Tacrolimus Therapy
Authors: Nishimura Akira , Ueno Tamaki , Kaneda Daisuke , Miyanomae Yuri , Chiyonobu Tomohiro , Morimoto Masafumi , Hosoi Hajime , Tozawa Takenori
Published: January 2018

Seronegative myasthenia gravis (MG) is a generalized form of MG that is diagnosed on the basis of clinical symptoms, electrophysiological testing, and pharmacological responses, in the absence of a seropositive status for anti-acetylcholine receptor (AChR) antibodies. Generalized MG that is seronegative for anti-AChR, anti-muscle-specific kinase (MuSK), and anti-low density lipoprotein receptor related protein 4 (Lrp4) antibodies is known as triple-seronegative MG. We here describe a case of triple-seronegative MG in an 8-year-old boy. His first symptom was dysphagia, at 3 years of age, and he subsequently developed ptosis, rhinolalia, and a waddling gait. A genetic analysis was conducted to exclude the possibility of congenital myasthenia syndrome due to the patient's resistance to steroid therapy. His condition was successfully managed with tacrolimus therapy over a 5-year follow-up period. Recently, several studies have reported the therapeutic utility of tacrolimus in juvenile seropositive MG; in contrast, a few reports have described tacrolimus treatment in cases of seronegative MG. Our findings suggest that tacrolimus therapy is a safe and effective option for the treatment of juvenile seronegative MG.
Hürden bei der Digitalisierung der Medizin in Deutschland – eine Expertenbefragung
Authors: Nohl-Deryk Pascal , Brinkmann Jesaja , Gerlach Ferdinand , Schreyögg Jonas , Achelrod Dmitrij
Published: January 2018

Hintergrund Digitale Medizin ist ein im Aufschwung befindlicher Bereich des Gesundheitswesens und birgt große Potenziale. Dennoch ist der Digitalisierungsgrad des deutschen Gesundheitswesens sowohl im internationalen Vergleich als auch im innerdeutschen Branchenvergleich gering. Trotz politischer Bemühungen scheinen bestimmte Hürden den Digitalisierungsprozess stark zu hemmen.

Methode Insgesamt 18 repräsentative Experten aus verschiedenen Bereichen wurden mit semi-strukturierten Interviews zu Hürden und Lösungsansätzen der Digitalisierung des Gesundheitswesens befragt. Die Auswertung erfolgte mittels Thematic Analysis nach Braun und Clarke.

Ergebnisse Die Interviewpartner identifizierten akteursspezifische und -übergreifende Hürden. Bei Selbstverwaltung und Ärzteschaft fehle teilweise der Wille und eine potente Organisationsstruktur, um die Digitalisierung voranzutreiben. Auf akteursübergreifender Ebene wird hervorgehoben, dass ein fehlender Nutzennachweis und Interoperabilität ein primäres Hemmnis darstellen, die aktuelle Gesetzgebung und Finanzierung hingegen kaum. Lösungsansätze werden insbesondere in einer Stärkung der Patientenrolle und in gesetzlichen Regelungen gesehen. Insbesondere Infrastrukturausbau und Interoperabilität würden ein koordiniertes, staatliches Eingreifen erfordern. Eine positive Kommunikation über Möglichkeiten und Nutzen digitaler Lösungen sei zusätzlich wichtig.

Schlussfolgerung Ein fester politischer Wille, eine übergreifende Strategie, begleitet durch ein Kommunikationskonzept scheinen notwendig zu sein. Gesetzgeberisch können verbindliche Vorgaben, Fristen und Sanktionen für die Selbstverwaltung hilfreich sein, gleichzeitig sollten Anwender früh mit in die Entwicklung eingezogen werden und positive Anreize zur Nutzung digitaler Lösungen geschaffen werden.
Online-Sexualaufklärung auf YouTube: Bestandsaufnahme und Handlungsempfehlungen für die Sexualpädagogik
Authors: Döring Nicola
Published: January 2018

Jugendliche in Deutschland präferieren inzwischen mehrheitlich Sexualaufklärung per Internet vor allen anderen Medien und Vertrauenspersonen.
Online-Sexualaufklärung findet oft über die Videoplattform YouTube statt, da YouTube neben Google die beliebteste Anlaufstelle im Internet
ist. Somit stellt sich die Frage, wie die Online-Sexualaufklärung auf YouTube aus sexualpädagogischer Perspektive einzuschätzen ist. Auf der
Basis der wissenschaftlichen Fachliteratur sowie einer Analyse der YouTube-Inhalte wird erläutert, 1) wer heutzutage deutschsprachige
YouTube-Kanäle zur Sexualaufklärung anbietet, 2) welche Inhalte und Qualität die Aufklärungsvideos haben und 3) was wir über Nutzende,
Nutzungsweisen und Wirkungen wissen. Erstmals werden mehr als 30 einschlägige deutschsprachige YouTube-Kanäle zur Sexualaufklärung
identifiziert und vorgestellt. Es zeigt sich, dass im boomenden Feld der Online-Sexualaufklärung auf YouTube die professionelle
Sexualpädagogik bislang eine randständige Rolle spielt. Der Beitrag diskutiert, wie YouTube in die sexualpädagogische Forschung und Praxis
sowie in die Öffentlichkeitsarbeit und Fortbildung der Fachdisziplin sinnvoll einzubinden ist. Eine zeitgemäße und professionelle
Sexualpädagogik muss sich auf die Bedingungen des Digitalzeitalters einstellen. Andernfalls läuft sie Gefahr, den Kontakt zu den Zielgruppen
zu verlieren und die Definitionsmacht über Fragen sexueller Gesundheit und sexueller Bildung denjenigen zu überlassen, die digitale Medien
einschließlich YouTube bereits strategisch und ideologisch nutzen. YouTube und andere soziale Medien sind dabei natürlich kein Allheilmittel
und auch kein Ersatz für herkömmliche Kommunikationskanäle und Bildungssettings, sondern eine wichtige Ergänzung.
Numerical study on antiknock measures of concrete gravity dam bearing underwater contact blast loading
Authors: Xu Qiang , Chen Jianyun , Li Jing , Cao Yang , Liu Xiaopeng , Yu Xianzheng , Cao Xiangyu
Published: January 2018

A concrete gravity dam (CGD) bearing underwater contact blast loading is important to estimate the explosion resistance of CGD. The blast resistant measure on aluminum foam of CGD is proposed by simulating the CGD subjected to underwater contact blast loading in this paper. Taking full advantages of the Euler and Lagrange methods, the Euler-Lagrange coupled method was used to simulate the above situations. Specifically, the Euler method was adopted to simulate explosive, reservoir water, and air. Meanwhile, the Lagrange method was used to simulate the CGD. The Koyna CGD subjected to underwater contact blast loading was simulated. The rules of crack distributions and dynamic responses of the Koyna CGD were studied to propose the arrangement form of the aluminum foam as the antiknock material and analyze the antiknock performance of that. The results show that aluminum foam, as an antiknock material, could effectively reduce the amplitude of the pressure wave and the dynamic response. It has more advantages of reducing horizontal, vertical, and inclined cracks and weakening the water cut effect.
Kinetic step-growth polymerization: A dissipative particle dynamics simulation study
Authors: Xu Dan , Ni Chun-Yan , Zhu You-Liang , Lu Zhong-Yuan , Xue Yao-Hong , Liu Hong
Published: January 2018

Kinetic step-growth polymerization is studied by dissipative particle dynamics coupled with our previously developed reaction algorithm on a coarse-grained level. The simulation result proves that this step-growth polymerization obeys the second-order reaction kinetics. We apply this algorithm to study the step-growth polymerization using the subunits with different flexibilities or within confinement. Good agreement of the number fraction distributions with the Flory distribution is obtained, implying that this algorithm is reasonable to describe such a kind of step-growth polymerization. This algorithm can further supply a convenient platform for simulating typical step-growth polymerization in reactive polymer systems.
Elliptical spreading characteristics of a liquid metal droplet impact on a glass surface under a horizontal magnetic field
Authors: Yang Juan-Cheng , Qi Tian-Yu , Han Tian-Yang , Zhang Jie , Ni Ming-Jiu
Published: January 2018

The spreading characteristics of a liquid GaInSn alloy droplet on a glass surface with the action of a horizontal magnetic field have been experimentally investigated in the present paper. With changing the impact velocity from 0.1 m/s to 1.2 m/s and increasing the magnetic field from 0 T to 1.6 T, we focus on studying the influence of the horizontal magnetic field on the spreading characteristics of a liquid metal droplet using the shadow-graph method. The elliptical spreading pattern of a liquid metal droplet induced by the horizontal magnetic field was discovered by experiments. By introducing a numerical method in getting the distribution of current lines and the Lorentz force inside the droplet, we give a detailed explanation on the mechanism of elliptical spreading. Furthermore, some quantitative results on a maximum spreading factor and time at moment of maximum spreading varied with the Hartmann number and Weber number are shown to give us a comprehensive understanding of the elliptical spreading. With the increasing of the magnetic field, the maximum spreading factor in the front view is reduced while that in the side view is increased, which reveals a larger deformation happened during the spreading process. While with the increasing of impact velocity, the spreading factor increased. Finally, we present a non-dimensional parameter to get scaling laws for the averaged maximum spreading factor and the aspect ratio of the maximum spreading factor; results show that the predict data can agree with experimental data in a certain degree.
Low Rm magnetohydrodynamics as a means of measuring the surface shear viscosity of a liquid metal: A first attempt on Galinstan
Authors: Delacroix Jules , Davoust Laurent , Patouillet Kévin
Published: January 2018

This paper introduces an experimental apparatus which generates the end-driven annular flow of a liquid metal pervaded by a uniform magnetic field. Unlike past viscometers involving an annular channel with particular values of the depth-to-width ratio, the present experiment enables us to drive the viscous shear at the surface of an annular liquid metal bath put in rotation. The magnetic interaction parameter N and the Boussinesq number related to the surface shear viscosity can be monitored from the magnitude of the applied magnetic field; the latter being set large enough for avoiding artefacts related to centrifugation and surface dilatation. This essential feature is obtained due to the ability of the magnetic field to set dimensionality of the annular flow in the channel between 2D-1/2 (swirling flow) and 2D axisymmetric (extinction of the overturning flow if N is large enough). By tracking the azimuthal velocity of tracers seeded along the oxidised surface of liquid Galinstan, an estimate for the surface shear viscosity of a liquid metal can be given.
Effect of cooling rate on magnetic domain structure and magnetic properties of Tb0.27Dy0.73Fe1.95 alloys solidified in high magnetic field
Authors: Liu Tie , Dong Meng , Gao Pengfei , Xiao Yubao , Yuan Yi , Wang Qiang
Published: January 2018

In this work, Tb0.27Dy0.73Fe1.95 alloys were solidified in a high magnetic field of 4.4 T at various cooling rates. Changes in the magnetostriction, crystal orientation, magnetization, and magnetic domain of the solidified alloys were investigated. The application of the magnetic field can induce <111> orientation of (Tb, Dy)Fe2 phase. However, the effect of the magnetic field is strongly dependent on the cooling rate. The alloy solidified at 5 °C/min shows the highest magnetostriction, strongest <111> orientation, best contrast of light and dark in the domain image, and fastest magnetization, and followed in descending order by the alloys solidified at 1.5 °C/min and 60 °C/min. The change in the magnetostriction of the alloys can be attributed to the changes in crystal orientation and magnetic domain structure caused by both the magnetic field and cooling rate.
Characterizing protein conformations by correlation analysis of coarse-grained contact matrices
Authors: Lindsay Richard J. , Siess Jan , Lohry David P. , McGee Trevor S. , Ritchie Jordan S. , Johnson Quentin R. , Shen Tongye
Published: January 2018

We have developed a method to capture the essential conformational dynamics of folded biopolymers using statistical analysis of coarse-grained segment-segment contacts. Previously, the residue-residue contact analysis of simulation trajectories was successfully applied to the detection of conformational switching motions in biomolecular complexes. However, the application to large protein systems (larger than 1000 amino acid residues) is challenging using the description of residue contacts. Also, the residue-based method cannot be used to compare proteins with different sequences. To expand the scope of the method, we have tested several coarse-graining schemes that group a collection of consecutive residues into a segment. The definition of these segments may be derived from structural and sequence information, while the interaction strength of the coarse-grained segment-segment contacts is a function of the residue-residue contacts. We then perform covariance calculations on these coarse-grained contact matrices. We monitored how well the principal components of the contact matrices is preserved using various rendering functions. The new method was demonstrated to assist the reduction of the degrees of freedom for describing the conformation space, and it potentially allows for the analysis of a system that is approximately tenfold larger compared with the corresponding residue contact-based method. This method can also render a family of similar proteins into the same conformational space, and thus can be used to compare the structures of proteins with different sequences.
Relativistic extension of a charge-conservative finite element solver for time-dependent Maxwell-Vlasov equations
Authors: Na D.-Y. , Moon H. , Omelchenko Y. A. , Teixeira F. L.
Published: January 2018

Accurate modeling of relativistic particle motion is essential for physical predictions in many problems involving vacuum electronic devices, particle accelerators, and relativistic plasmas. A local, explicit, and charge-conserving finite-element time-domain (FETD) particle-in-cell (PIC) algorithm for time-dependent (non-relativistic) Maxwell-Vlasov equations on irregular (unstructured) meshes was recently developed by Moon et al. [Comput. Phys. Commun. 194, 43 (2015); IEEE Trans. Plasma Sci. 44, 1353 (2016)]. Here, we extend this FETD-PIC algorithm to the relativistic regime by implementing and comparing three relativistic particle-pushers: (relativistic) Boris, Vay, and Higuera-Cary. We illustrate the application of the proposed relativistic FETD-PIC algorithm for the analysis of particle cyclotron motion at relativistic speeds, harmonic particle oscillation in the Lorentz-boosted frame, and relativistic Bernstein modes in magnetized charge-neutral (pair) plasmas.
Chiroptic response of ferroelectric liquid crystals triggered with localized surface plasmon resonance of achiral gold nanorods
Authors: Podgornov F. V. , Haase W.
Published: January 2018

The chiroptic response of a multi-component molecular mixture [chiral smectic C (SmC*) liquid crystal] modified by achiral capped gold nanorods (GNRs) has been reported. The dispersion of the GNRs (radius rGNR = 5 × 10−9 m; length L = 4.5 × 10−8 m) with two concentrations (0.1 wt. % and 0.5 wt. %) resulted in the concentration dependent change in the circular dichroism (CD) spectrum of the SmC*-GNR complex. Three effects could be responsible for the change in the chiroptic properties of the SmC* liquid crystal. The first one is the stabilization of the helical superstructure due to the GNRs. The second one is the change in the angle between the transition electric and magnetic dipole moments near the absorption bands due to the influence of the longitudinal surface plasmon resonances (LSPRs) excited in nanorods. The third effect is the induction of chiral current in gold nanorods by the chiral component of the mixture. The latter phenomenon leads to the broad CD band at the wavelength of the LSPR.
Modulated spin orbit torque in a Pt/Co/Pt/YIG multilayer by nonequilibrium proximity effect
Authors: Liu Q. B. , Meng K. K. , Cai Y. Z. , Qian X. H. , Wu Y. C. , Zheng S. Q. , Jiang Y.
Published: January 2018

We have compared the spin orbit torque (SOT) induced magnetization switching in Pt/Co/Pt/Y3Fe5O12 (YIG) and Pt/Co/Pt/SiO2 multilayers. The critical switching current in Pt/Co/Pt/YIG is almost half of that in Pt/Co/Pt/SiO2. Through harmonic measurements, we demonstrated the enhancement of the effective spin Hall angle in Pt/Co/Pt/YIG. The increased efficiency of SOT is ascribed to the nonequilibrium proximity effect at the Pt/YIG interface, which suppresses the spin current reflection and enhances the effective spin accumulation at the Co/Pt interface. Our method can effectively reduce the switching current density and provide another way to modulate SOT.
Dependence of magnetic properties on different buffer layers of Mn3.5Ga thin films
Authors: Takahashi Y. , Sato K. , Shima T. , Doi M.
Published: January 2018

D022-Mn3.5Ga thin films were prepared on MgO (100) single crystalline substrates with different buffer layer (Cr, Fe, Cr/Pt and Cr/Au) using an ultra-high-vacuum electron beam vapor deposition system. From XRD patterns, a fundamental (004) peak has clearly observed for all samples. The relatively low saturation magnetization (Ms) of 178 emu/cm3, high magnetic anisotropy (Ku) of 9.1 Merg/cm3 and low surface roughness (Ra) of 0.30 nm were obtained by D022-Mn3.5Ga film (20 nm) on Cr/Pt buffer layer at Ts = 300 °C, Ta = 400 °C (3h). These findings suggest that MnGa film on Cr/Pt buffer layer is a promising PMA layer for future spin electronics devices.
Uniform magnetic fields in density-functional theory
Authors: Tellgren Erik I. , Laestadius Andre , Helgaker Trygve , Kvaal Simen , Teale Andrew M.
Published: January 2018

We construct a density-functional formalism adapted to uniform external magnetic fields that is intermediate between conventional density functional theory and Current-Density Functional Theory (CDFT). In the intermediate theory, which we term linear vector potential-DFT (LDFT), the basic variables are the density, the canonical momentum, and the paramagnetic contribution to the magnetic moment. Both a constrained-search formulation and a convex formulation in terms of Legendre–Fenchel transformations are constructed. Many theoretical issues in CDFT find simplified analogs in LDFT. We prove results concerning N-representability, Hohenberg–Kohn-like mappings, existence of minimizers in the constrained-search expression, and a restricted analog to gauge invariance. The issue of additivity of the energy over non-interacting subsystems, which is qualitatively different in LDFT and CDFT, is also discussed.
Effect of cobalt substitution on magnetic properties of Ba4Ni2−xCoxFe36O60 hexaferrite
Authors: Jiang Xiaona , Li Songze , Yu Zhong , Harris Vincent G. , Su Zhijuan , Sun Ke , Wu Chuanjian , Guo Rongdi , Lan Zhongwen
Published: January 2018

Co-substituted U-type hexagonal ferrite bulks, with composition of Ba4Ni2−xCoxFe36O60 (x=0.2, 0.4, 0.6, 0.8), were prepared by a conventional ceramic method. Saturation magnetization (4πMs), coercivity (Hc), and Curie temperature (Tc) were investigated. Anisotropy constant (K1) was calculated by fitting the magnetization curve (M-H) according to the law of approach to saturation, and anisotropy field (Ha) was calculated accordingly. The results reveal that all the samples possess the U-type hexagonal crystallographic structure. With increasing cobalt substitution content (x), the lattice parameters (a and c) almost remain the same owing to the similar radii of Ni2+ (0.72 Å) Co2+ (0.74 Å) ions. 4πMs goes up, while Hc Hc shows an opposite trend. K1 and Ha monotonously decrease resulting from that cobalt substitution weakens the c-axis orientation. Additionally, Tc increases from 467 °C to 484 °C.
Morphological evolution of Ge/Si nano-strips driven by Rayleigh-like instability
Authors: Salvalaglio Marco , Zaumseil Peter , Yamamoto Yuji , Skibitzki Oliver , Bergamaschini Roberto , Schroeder Thomas , Voigt Axel , Capellini Giovanni
Published: January 2018

We present the morphological evolution obtained during the annealing of Ge strips grown on Si ridges as a prototypical process for 3D device architectures and nanophotonic applications. In particular, the morphological transition occurring from Ge/Si nanostrips to nanoislands is illustrated. The combined effect of performing annealing at different temperatures and varying the lateral size of the Si ridge underlying the Ge strips is addressed by means of a synergistic experimental and theoretical analysis. Indeed, three-dimensional phase-field simulations of surface diffusion, including the contributions of both surface and elastic energy, are exploited to understand the outcomes of annealing experiments. The breakup of Ge/Si strips, due to the activation of surface diffusion at high temperature, is found to be mainly driven by surface-energy reduction, thus pointing to a Rayleigh-like instability. The residual strain is found to play a minor role, only inducing local effects at the borders of the islands and an enhancement of the instability.
All-dry transferred single- and few-layer MoS2 field effect transistor with enhanced performance by thermal annealing
Authors: Islam Arnob , Lee Jaesung , Feng Philip X.-L.
Published: January 2018

We report on the experimental demonstration of all-dry stamp transferred single- and few-layer (1L to 3L) molybdenum disulfide (MoS2) field effect transistors (FETs), with a significant enhancement of device performance by employing thermal annealing in moderate vacuum. Three orders of magnitude reduction in both contact and channel resistances have been attained via thermal annealing. We obtain a low contact resistance of 22 kΩ μm after thermal annealing of 1L MoS2 FETs stamp-transferred onto gold (Au) contact electrodes. Furthermore, nearly two orders of magnitude enhancement of field effect mobility are also observed after thermal annealing. Finally, we employ Raman and photoluminescence measurements to reveal the phenomena of alloying or hybridization between 1L MoS2 and its contacting electrodes during annealing, which is responsible for attaining the low contact resistance.
Study of the parametric dependence of linear and nonlinear microtearing modes in conventional tokamak discharges
Authors: Rafiq T. , Kritz A. H. , Weiland J. , Luo L. , Schuster E.
Published: January 2018

A reduced transport model for microtearing modes is developed for use in integrated predictive modeling studies, employing a unified fluid/kinetic approach to derive the nonlinear dispersion relation. This approach advances the kinetic description and allows the inclusion of nonlinear effects due to magnetic fluctuations. In this numerical study, the dependence of the microtearing mode real frequency and growth rate on plasma parameters and on DIII-D like L-mode and H-mode plasma profiles is examined. The magnetic fluctuation strength as well as electron thermal diffusivity due to microtearing modes is computed. The saturated amplitude of the magnetic fluctuations is calculated utilizing numerically determined microtearing mode eigenvalues in the nonlinear microtearing modes envelope equation. It is found that the electron temperature gradient in the presence of moderate collision frequency is required for the microtearing mode to become unstable. The effects of small and large collisionality and small and large wavenumbers on microtearing modes are found to be stabilizing, while the effects of density gradient, plasma beta, low current density, and large magnetic shear are found to be destabilizing. The microtearing mode growth rate, magnetic fluctuation strength, as well as electron thermal diffusivity is found to be larger in the H-mode plasma than in the L-mode plasma.
Luminescent N-polar (In,Ga)N/GaN quantum wells achieved by plasma-assisted molecular beam epitaxy at temperatures exceeding 700 °C
Authors: Chèze C. , Feix F. , Lähnemann J. , Flissikowski T. , Kryśko M. , Wolny P. , Turski H. , Skierbiszewski C. , Brandt O.
Published: January 2018

Previously, we found that N-polar (In,Ga)N/GaN quantum wells prepared on freestanding GaN substrates by plasma-assisted molecular beam epitaxy at conventional growth temperatures of about 650 °C do not exhibit any detectable luminescence even at 10 K. In the present work, we investigate (In,Ga)N/GaN quantum wells grown on Ga- and N-polar GaN substrates at a constant temperature of 730 °C. This exceptionally high temperature results in a vanishing In incorporation for the Ga-polar sample. In contrast, quantum wells with an In content of 20% and abrupt interfaces are formed on N-polar GaN. Moreover, these quantum wells exhibit a spatially uniform green luminescence band up to room temperature, but the intensity of this band is observed to strongly quench with temperature. Temperature-dependent photoluminescence transients show that this thermal quenching is related to a high density of nonradiative Shockley-Read-Hall centers with large capture coefficients for electrons and holes.
Electric field assisted sintering to improve the performance of nanostructured dye sensitized solar cell (DSSC)
Authors: Shojaeifar Mohsen , Mohajerani Ezeddin , Fathollahi Mohammadreza
Published: January 2018

Herein, we report the application of electric field assisted sintering (EFAS) procedure in dye sensitized solar cells (DSSCs). The EFAS process improved DSSC performance by enhancing optical and electrical characteristics simultaneously. The EFAS procedure is shown to be capable of reducing the TiO2 nanoparticle aggregation leading to the higher surface area for dye molecules adsorbates. Lower nanoparticle aggregation can be evidently observed by field emission scanning electron microscopy imaging. By applying an external electric field, the current density and conversion efficiency improved significantly about 30% and 45%, respectively. UV-Visible spectra of the desorbed dye molecules on the porous nanoparticles bedding confirm a higher amount of dye loading in the presence of an external electric field. Correspondingly, comprehensive J-V characteristics modeling reveals the enhancement of the diffusion coefficient by EFAS process. The proposed method can be applied to improve the efficiency of the mesostructured hybrid perovskite solar cells, photodetectors, and quantum dot-sensitized solar cells, as well as reduction of the surface area loss in all porous media.
Control of radial propagation and polarity in a plasma jet in surrounding Ar
Authors: Gong W. , Yue Y. , Ma F. , Yu F. , Wan J. , Nie L. , Bazaka K. , Xian Y. , Lu X. , Ostrikov K.
Published: January 2018

In recent years, the use of shielding gas to prevent the diffusion of the ambient air, particularly oxygen and nitrogen species, into the effluent of the atmospheric pressure plasma jet, and thus control the nature of chemical species used in the plasma treatment has increased. In this paper, the radial propagation of a plasma jet in ambient Ar is examined to find the key determinants of the polarity of plasma jets. The dynamics of the discharge reveal that the radial diffusion discharge is a special phenomenon observed only at the falling edge of the pulses. The radial transport of electrons, which is driven by the radial component of the applied electric field at the falling edge of the pulse, is shown to play an important role in increasing the seed electron density in the surrounding Ar. This result suggests a method to provide seed electrons at atmospheric pressure with a negative discharge. The polarity of the plasma jet is found to be determined by the pulse width rather than the polarity of the applied voltage, as it dictates the relative difference in the intensity of the two discharges in a single pulse, where the stronger discharge in a pulse dominates the behavior of the plasma jet. Accordingly, a method to control the polarity of a plasma jet through varying the pulse width is developed. Since plasma jets of different polarities differ remarkably in terms of their characteristics, the method to control the polarity reported in this paper will be of use for such applications as plasma-enhanced processing of materials and plasma biomedicine.
Microsphere-assisted super-resolution imaging with enlarged numerical aperture by semi-immersion
Authors: Wang Fengge , Yang Songlin , Ma Huifeng , Shen Ping , Wei Nan , Wang Meng , Xia Yang , Deng Yun , Ye Yong-Hong
Published: January 2018

Microsphere-assisted imaging is an extraordinary simple technology that can obtain optical super-resolution under white-light illumination. Here, we introduce a method to improve the resolution of a microsphere lens by increasing its numerical aperture. In our proposed structure, BaTiO3 glass (BTG) microsphere lenses are semi-immersed in a S1805 layer with a refractive index of 1.65, and then, the semi-immersed microspheres are fully embedded in an elastomer with an index of 1.4. We experimentally demonstrate that this structure, in combination with a conventional optical microscope, can clearly resolve a two-dimensional 200-nm-diameter hexagonally close-packed (hcp) silica microsphere array. On the contrary, the widely used structure where BTG microsphere lenses are fully immersed in a liquid or elastomer cannot even resolve a 250-nm-diameter hcp silica microsphere array. The improvement in resolution through the proposed structure is due to an increase in the effective numerical aperture by semi-immersing BTG microsphere lenses in a high-refractive-index S1805 layer. Our results will inform on the design of microsphere-based high-resolution imaging systems.
Tunable modulation of refracted lamb wave front facilitated by adaptive elastic metasurfaces
Authors: Li Shilong , Xu Jiawen , Tang J.
Published: January 2018

This letter reports designs of adaptive metasurfaces capable of modulating incoming wave fronts of elastic waves through electromechanical-tuning of their cells. The proposed elastic metasurfaces are composed of arrayed piezoelectric units with individually connected negative capacitance elements that are online tunable. By adjusting the negative capacitances properly, accurately formed, discontinuous phase profiles along the elastic metasurfaces can be achieved. Subsequently, anomalous refraction with various angles can be realized on the transmitted lowest asymmetric mode Lamb wave. Moreover, designs to facilitate planar focal lenses and source illusion devices can also be accomplished. The proposed flexible and versatile strategy to manipulate elastic waves has potential applications ranging from structural fault detection to vibration/noise control.
Selective control of vortex polarities by microwave field in two robustly synchronized spin-torque nano-oscillators
Authors: Li Yi , de Milly Xavier , Klein Olivier , Cros Vincent , Grollier Julie , de Loubens Grégoire
Published: January 2018

Manipulating operation states of coupled spin-torque nano-oscillators (STNOs), including their synchronization, is essential for applications such as complex oscillator networks. In this work, we experimentally demonstrate selective control of two coupled vortex STNOs through microwave-assisted switching of their vortex core polarities. First, the two oscillators are shown to synchronize due to the dipolar interaction in a broad frequency range tuned by an external biasing field. Coherent output is demonstrated along with strong linewidth reduction. Then, we show individual vortex polarity control of each oscillator, which leads to synchronization/desynchronization due to accompanied frequency shift. Our methods can be easily extended to multiple-element coupled oscillator networks.
Probing dynamic behavior of electric fields and band diagrams in complex semiconductor heterostructures
Authors: Turkulets Yury , Shalish Ilan
Published: January 2018

Modern bandgap engineered electronic devices are typically made of multi-semiconductor multi-layer heterostructures that pose a major challenge to silicon-era characterization methods. As a result, contemporary bandgap engineering relies mostly on simulated band structures that are hardly ever verified experimentally. Here, we present a method that experimentally evaluates bandgap, band offsets, and electric fields, in complex multi-semiconductor layered structures, and it does so simultaneously in all the layers. The method uses a modest optical photocurrent spectroscopy setup at ambient conditions. The results are analyzed using a simple model for electro-absorption. As an example, we apply the method to a typical GaN high electron mobility transistor structure. Measurements under various external electric fields allow us to experimentally construct band diagrams, not only at equilibrium but also under any other working conditions of the device. The electric fields are then used to obtain the charge carrier density and mobility in the quantum well as a function of the gate voltage over the entire range of operating conditions of the device. The principles exemplified here may serve as guidelines for the development of methods for simultaneous characterization of all the layers in complex, multi-semiconductor structures.
The role of conductivity discontinuities in design of cardiac defibrillation
Authors: Lim Hyunkyung , Cun Wenjing , Wang Yue , Gray Richard A. , Glimm James
Published: January 2018

Fibrillation is an erratic electrical state of the heart, of rapid twitching rather than organized contractions. Ventricular fibrillation is fatal if not treated promptly. The standard treatment, defibrillation, is a strong electrical shock to reinitialize the electrical dynamics and allow a normal heart beat. Both the normal and the fibrillatory electrical dynamics of the heart are organized into moving wave fronts of changing electrical signals, especially in the transmembrane voltage, which is the potential difference between the cardiac cellular interior and the intracellular region of the heart. In a normal heart beat, the wave front motion is from bottom to top and is accompanied by the release of Ca ions to induce contractions and pump the blood. In a fibrillatory state, these wave fronts are organized into rotating scroll waves, with a centerline known as a filament. Treatment requires altering the electrical state of the heart through an externally applied electrical shock, in a manner that precludes the existence of the filaments and scroll waves. Detailed mechanisms for the success of this treatment are partially understood, and involve local shock-induced changes in the transmembrane potential, known as virtual electrode alterations. These transmembrane alterations are located at boundaries of the cardiac tissue, including blood vessels and the heart chamber wall, where discontinuities in electrical conductivity occur. The primary focus of this paper is the defibrillation shock and the subsequent electrical phenomena it induces. Six partially overlapping causal factors for defibrillation success are identified from the literature. We present evidence in favor of five of these and against one of them. A major conclusion is that a dynamically growing wave front starting at the heart surface appears to play a primary role during defibrillation by critically reducing the volume available to sustain the dynamic motion of scroll waves; in contrast, virtual electrodes occurring at the boundaries of small, isolated blood vessels only cause minor effects. As a consequence, we suggest that the size of the heart (specifically, the surface to volume ratio) is an important defibrillation variable.
Wild seedlings of a tree endemic on granite outcrops show no evidence of inbreeding depression
Authors: Bezemer Nicole
Published: January 2018

Plant communities on granite outcrops are characterised by high biodiversity and endemism, and strong population genetic structuring. The floristic diversity and structure of inselberg flora receives much attention in international conservation research, yet our understanding of how recruitment influences population genetic structure of plants endemic to granite outcrops is limited. To determine the immediate genetic consequences of recruitment and to quantify mating and dispersal patterns by parentage analysis, I conducted an opportunistic study following a wildfire in a stand of the lignotuberous tree Eucalyptus caesia Benth. (Myrtaceae) at Boyagin Nature Reserve. The entire adult stand (n = 180) plus seedlings (n = 115) were genotyped with 14 microsatellite loci. Compared with adults, seedlings had low heterozygosity and a high inbreeding co-efficient, but similar levels of allelic diversity. There was no evidence of post-germination selection against homozygous seedlings over the 20 month survey period. Seedlings that resulted from cross-pollination were more heterozygous than seedlings resulting from selfing, but could not be distinguished based on height measurements or survivorship. Parentage analysis in CERVUS revealed mostly limited seed dispersal, assuming that candidate parents closest to seedlings were the maternal parent. By comparison, pollen movement was more extensive, yet still restricted to plants within the stand. Recruitment has increased the population size, but appears insufficient to enhance genetic diversity in the Boyagin stand of E. caesia. Nonetheless, E. caesia appears adept at persisting as extremely small populations.
Species relationships in the dasyurid marsupial genus Pseudantechinus (Marsupialia : Dasyuridae): a re-examination of the taxonomic status of Pseudantechinus roryi
Authors: Umbrello L. S. , Woolley P. A. , Westerman M.
Published: January 2018

The status of Pseudantechinus roryi relative to its congeners has been determined from DNA sequences obtained from both nuclear and mitochondrial gene loci. Although all other recognised species of Pseudantechinus form reciprocally monophyletic lineages in phylogenetic analyses, individuals identified in museum collections as Ps. roryi (including type specimens) were indistinguishable from those identified as Ps. macdonnellensis. Ps. roryi is thus considered to be a synonym of Ps. macdonnellensis. Neighbour-joining network analyses failed to reveal any clear biogeographic differences between populations of Ps. macdonnellensis other than some evidence of isolation by distance.
Chronic anthropogenic noise disrupts glucocorticoid signaling and has multiple effects on fitness in an avian community
Authors: Kleist Nathan J. , Guralnick Robert P. , Cruz Alexander , Lowry Christopher A. , Francis Clinton D.
Published: January 2018

Significance

Studies examining relationships among habitat disturbance, physiology, and fitness in wild animals often produce contradictory or inconclusive results, casting doubt on current conservation physiology predictive frameworks linking stress and fitness. We apply a new framework drawn from experimental systems utilizing chronic inescapable stressors to explore how noise, an environmental stimulus common to wildlife habitats worldwide, disrupts stress hormone signaling and impacts fitness. We utilize a natural experiment to show that chronic, anthropogenic noise reduced baseline corticosterone levels, increased acute corticosterone response, and, at highest amplitudes, negatively impacted multiple measures of fitness across three species of birds. Our work brings conservation physiology theory involving wild animals into needed alignment with recent theories based on chronic stress in laboratory studies.
Mechanism-specific assay design facilitates the discovery of Nav1.7-selective inhibitors
Authors: Chernov-Rogan Tania , Li Tianbo , Lu Gang , Verschoof Henry , Khakh Kuldip , Jones Steven W. , Beresini Maureen H. , Liu Chang , Ortwine Daniel F. , McKerrall Steven J. , Hackos David H. , Sutherlin Daniel , Cohen Charles J. , Chen Jun
Published: January 2018

Significance

Subtype-selective modulation of ion channels is often important, but extremely difficult to achieve for drug development. Using Nav1.7 as an example, we show that this challenge could be attributed to poor design in ion channel assays, which fail to detect most potent and selective compounds and are biased toward nonselective mechanisms. By exploiting different drug binding sites and modes of channel gating, we successfully direct a membrane potential assay toward non–pore-blocking mechanisms and identify Nav1.7-selective compounds. Our mechanistic approach to assay design addresses a significant hurdle in Nav1.7 drug discovery and is applicable to many other ion channels.