bluuebunny/crossref_metadata_2025 huggingface dataset:
Integration of a solar cooling and heating system. Case of a residential building located in Blida region
Authors: Sami Sabrina , Kaci Karim , EL.Ganaoui Mohamed , Ouhsaine Lahoucine
Published: February 2020

The object of the present study is the integration of a solar cooling and heating system of a residential building (4-flour) located in Blida region in Algeria. The system consists of a set of solar collectors that supply energy to a balloon through an external heat exchanger. The solar and auxiliary tanks are connected by a heat exchanger immersed in the bottom of the auxiliary tank. In the distribution loop, a recirculation can make possible to obtain the domestic hot water set point temperature. A cold production system is directly connected to the solar tank and a regulation system ensures the control of the installation. We have used the TRANSOL software under TRANSYS to calculate the heating and cooling load. Several parameters are then introduced to size and evaluate the performance of our installation. The results obtained are satisfactory .
Double-diffusive mixed convection of pseudoplastic fluids in an inclined square cavity partially heated
Authors: Toudja Nihal , Labsi Nabila , Khaled Benkahla Youb , Boutra Abdelkader , Ouyahia Seif-Eddine , Benzema Mahdi
Published: February 2020

Mixed convection heat and mass transfer in an inclined square cavity partially heated is numerically studied in the present paper. The cavity is filled with a non-Newtonian pseudoplastic fluid. The governing equations are solved numerically using the finite volume method. The velocitypressure coupling is achieved using the SIMPLER algorithm. This study focuses on the effect of some parameters, namely, the Richardson number and the power law index, on the flow pattern as well as on heat and mass transfer rates. The results indicate that the increase of the Richardson number decreases both heat and mass transfer rates. However, the latter are improved with the increase of the power law index whatever the value of the Richardson number.
Erosive pustulöse Dermatose der Kopfhaut
Authors: Vorobyev A. , Zillikens D. , Kahle B.
Published: February 2020

Ausgedehnte erosive Hautveränderungen an der Kopfhaut älterer Menschen können ein therapeutisches Problem darstellen. Auch die diagnostische Einordnung dieser Veränderungen kann eine Herausforderung darstellen. Wir berichten über den Fall eines 83-jährigen Patienten mit seit mehreren Jahren rezidivierenden Erosionen am Kapillitium. Unter dem Verdacht auf epitheliale Neoplasien waren bereits mehrere Hautbiopsien entnommen worden, die meist unspezifische Entzündungen zeigten. Nur bei einzelnen Läsionen waren oberflächliche, initial invasive epitheliale Tumore nachgewiesen worden. Unter lokalen antiseptischen Maßnahmen und einer photodynamischen Therapie heilten diese Läsionen ab.
Implementierung von aktivierenden pflegerischen Konzepten für Menschen mit Demenz
Authors: Morgenstern Ulrike
Published: February 2020

Menschen mit Demenz haben einen Anspruch darauf, optimal versorgt und in ihren Ressourcen gefördert zu werden. Hierzu existieren zahlreiche Konzepte, zum Beispiel die „Aktivierung mit Brain-Gym®“. Doch wie können Fachkräfte optimal geschult werden, damit sie diese Aktivierungen auch im Pflegealltag umsetzen? Und wie bereit sind Pflegeeinrichtungen, solche Konzepte nachhaltig zu implementieren? Eine Studie gibt Antworten.
General Route to Purin-2-ylmagnesium Halides by Metal–Halogen Exchange in Dichloromethane
Authors: Gazzola Silvia , Gordon Malcolm R. , Lindell Stephen D.
Published: February 2020

Treatment of a solution of a 9-alkyl- or 9-aryl-2-iodopurine in dichloromethane with an ethereal solution of ethylmagnesium bromide at –5 °C generates the corresponding purin-2-ylmagnesium bromide, which reacts with aldehydes to give the corresponding 2-(hydroxyalkyl)purines in yields of 53–84%. The purin-2-yl Grignard reagents show good functional-group tolerance to ester and nitro groups, and the method permits the synthesis of the previously unknown 6-unsubstituted 2-magnesiopurines for the first time. Performing the same procedure in THF as solvent resulted either in extensive decomposition or rapid isomerization to give purin-8-ylmagnesium halides.
Basic Understanding of Temporomandibular Joint and Its Dysfunction among Undergraduate Students—A Survey Report
Authors: Dandekeri Shilpa , Kavassery pooja B. , Hegde Chethan , Kumar Sowmya M. , Shetty Bharathraj
Published: February 2020

Background Temporomandibular disorder is the most commonly occurring type of orofacial pain. A general dental practitioner must be able to recognize and distinguish pain related to the joint to be capable of providing treatment or send for a referral. This survey was undertaken to test the undergraduate students in their residency program to analyze their skills in basic understanding and diagnostic capability relevant to temporomandibular joint (TMJ) disorder.

Materials and Methods A total of 110 dental students undergoing their residency program in the institute of A.B. Shetty Memorial Institute of Dental Sciences were selected. They were given a questionnaire pro forma to fill out which included questions regarding the anatomy, physiology, pathology, diagnosis, and treatment plan of TMJ disorders.

Results Note that 71.75% ± 6.13% of students answered anatomy questions correctly, 46.6% ± 28% answered physiology questions correctly, 34.67% ± 5.5% answered pathology questions correctly, 23.67% ± 2.5% answered diagnosis questions correctly, and 27.25% ± 15.8% answered questions of treatment plan correctly. Note that 100% of them understood the importance of TMJ in dentistry.

Conclusion This shows that there is an awareness about the basic understanding of the TMJ; however, to be able to clinically apply the knowledge and diagnose a disorder of TMJ, more than half of the participants were unacquainted of it and the curriculum should stress on improvement of this understanding at the undergraduate level itself.
Relation of Menarche, and Breast and Ovarian Cancer in Women
Authors: Bareppady Sunanda , Nayak Sabitha
Published: February 2020

Cancer is one of the leading causes of death in India and it has become an important public health problem, with more than 800,000 new cases being reported every year. In India, the most frequent cancers usually seen among women are those of cervix, uterus, breast, ovary, lip, oral cavity, and esophagus. Among these, breast and ovarian cancer are seen frequently in Indian women. The study is aimed at finding the relationship of menarche with breast and ovarian cancer, and also determining the association between types of cancer and selected demographic variables. A descriptive study was conducted on a sample consisting of 100 participants at the Justice K.S Hegde Charitable Hospital, Mangaluru. The result showed that majority (56%) of the sample experienced their first menarche at less than 13 years and had no family history of breast or ovarian cancer. Among the 100 women, 62% were diagnosed with breast cancer. There is a significant association between types of cancer and age. The p-value is 0.027 at (p < 0.05) level of significance. The study concluded that there is a significant association between types of cancer with age.
Quantitative, experimentally-validated, model of MoS2 nanoribbon Schottky field-effect transistors from subthreshold to saturation
Authors: Paletti Paolo , Fathipour Sara , Remškar Maja , Seabaugh Alan
Published: February 2020

We investigate the channel length dependence of the electrical characteristics of chemical vapor transport (CVT)-grown MoS2 nanoribbon (NR) Schottky barrier field-effect transistors to provide insights into the transport properties of such nanostructures. The MoS2 NRs form spontaneously during the CVT growth, without the application of etching. Back gated transmission line measurement FETs were fabricated on a 45μm-long NR with channel lengths ranging between 200 nm and 3μm. Contact and sheet resistances were extracted from the electrical measurements and their back-gate bias dependence was analyzed. Numerical modeling based on a virtual probe approach combined with the Landauer formalism shows excellent agreement with the measurements. The model enables a quantitative extraction of the intrinsic FET properties, e.g., mean-free-path and electron mobility, and their dependence on carrier density and investigation of plausible trap distributions. A record electron mobility for a MoS2 NR channel of ∼81cm2/Vs was achieved.
Addressing present pitfalls in 3D printing for tissue engineering to enhance future potential
Authors: Placone Jesse K. , Mahadik Bhushan , Fisher John P.
Published: February 2020

Additive manufacturing in tissue engineering has significantly advanced in acceptance and use to address complex problems. However, there are still limitations to the technologies used and potential challenges that need to be addressed by the community. In this manuscript, we describe how the field can be advanced not only through the development of new materials and techniques but also through the standardization of characterization, which in turn may impact the translation potential of the field as it matures. Furthermore, we discuss how education and outreach could be modified to ensure end-users have a better grasp on the benefits and limitations of 3D printing to aid in their career development.
Competition between ring-puckering and ring-opening excited state reactions exemplified on 5H-furan-2-one and derivatives
Authors: Schalk Oliver , Galiana Joachim , Geng Ting , Larsson Tobias L. , Thomas Richard D. , Fdez. Galván Ignacio , Hansson Tony , Vacher Morgane
Published: February 2020

The influence of ring-puckering on the light-induced ring-opening dynamics of heterocyclic compounds was studied on the sample 5-membered ring molecules γ-valerolactone and 5H-furan-2-one using time-resolved photoelectron spectroscopy and ab initio molecular dynamics simulations. In γ-valerolactone, ring-puckering is not a viable relaxation channel and the only available reaction pathway is ring-opening, which occurs within one vibrational period along the C—O bond. In 5H-furan-2-one, the C=C double bond in the ring allows for ring-puckering which slows down the ring-opening process by about 150 fs while only marginally reducing its quantum yield. This demonstrates that ring-puckering is an ultrafast process, which is directly accessible upon excitation and which spreads the excited state wave packet quickly enough to influence even the outcome of an otherwise expectedly direct ring-opening reaction.
Oxygen diffusion barriers for epitaxial thin-film heterostructures with highly conducting SrMoO3 electrodes
Authors: Salg Patrick , Zeinar Lukas , Radetinac Aldin , Walk Dominik , Maune Holger , Jakoby Rolf , Alff Lambert , Komissinskiy Philipp
Published: February 2020

Transition metal perovskite oxide SrMoO3 with a Mo4+ 4d2 electronic configuration exhibits a room-temperature resistivity of 5.1 μΩcm in a single-crystal form and, therefore, is considered a prominent conducting electrode material for all-oxide microelectronic devices. Stabilization of the unfavorable Mo4+ valence state in SrMoO3 thin films necessitates reductive growth conditions that are often incompatible with a highly oxidative environment necessary to grow epitaxial heterostructures with fully oxygenated functional layers (e.g., tunable dielectric BaxSr1−xTiO3). Interestingly, only a few unit cells of the perovskite titanate capping layers SrTiO3, BaTiO3, and Ba0.5Sr0.5TiO3 act as an efficient oxygen barrier and minimize SrMoO3 oxidation into electrically insulating SrMoO4 in the broad range of the thin-film growth parameters. The Mo valence state in SrMoO3, determined by x-ray photoelectron spectroscopy, is used to analyze oxygen diffusion through the capping layers. The lowest level of oxygen diffusion is observed in Ba0.5Sr0.5TiO3. A Ba0.5Sr0.5TiO3 film with a thickness of only 6 unit cells preserves the Mo4+ oxidation state in the SrMoO3 underlayer up to the oxygen partial pressure of 8 mTorr at the temperature of 630 °C. Results, therefore, indicate that SrMoO3 films covered with atomically thin Ba0.5Sr0.5TiO3 remain conducting in an oxygen environment and can be integrated into all-oxide thin-film heterostructures with other functional materials.
Numerical investigations on the deformation styles and stress distributions of hyperelastic/viscoelastic spheres during water entry
Authors: Yang Liu , Wei Yingjie , Wang Cong , Xia Weixue , Li Jiachuan
Published: February 2020

This paper investigates the water entry physics of hyperelastic/viscoelastic spheres, including their deformation styles and stress distributions. For this purpose, elastic spheres entering water are modeled by combining neo-Hookean hyperelasticity and Prony series viscoelasticity models in a structured framework, and the fluid flow is determined by numerically solving the Navier–Stokes equations. Based on the experimental results, the numerical method of the fluid–structure interaction problem is validated. The results show that after water entry, the elastic spheres present five typical deformation styles in a single sphere deformation period, resulting in a nested cavity. In addition, the stress distributions of the elastic sphere surface mainly experience four typical stages in a single deformation period. A quantitative analysis of the stress is performed to describe the variation in the stress with the dimensionless displacement of a curved path at every stage. Moreover, the stress peak of the elastic sphere surface migrates from the bottom to the top of the sphere during a single deformation period and increases with the increases in the material shear modulus and impact velocity.
Sub-micrometer near-field focusing of spin waves in ultrathin YIG films
Authors: Divinskiy B. , Thiery N. , Vila L. , Klein O. , Beaulieu N. , Ben Youssef J. , Demokritov S. O. , Demidov V. E.
Published: February 2020

We experimentally demonstrate tight focusing of a spin wave beam excited in extended nanometer-thick films of yttrium iron garnet by a simple microscopic antenna functioning as a single-slit near-field lens. We show that the focal distance and the minimum transverse width of the focal spot can be controlled in a broad range by varying the frequency/wavelength of spin waves and the antenna geometry. The experimental data are in good agreement with the results of numerical simulations. Our findings provide a simple solution for the implementation of magnonic nanodevices requiring a local concentration of the spin-wave energy.
Enhancement of light absorption in a WS2 monolayer using spacer and Au layers
Authors: Ansari N. , Mohebbi E. , Gholami F.
Published: February 2020

Among ultrathin transition metal dichalcogenides, WS2 monolayers with a direct bandgap have attracted intensive attention because of their narrow optical absorption centered at 619 nm. However, these layers with stronger absorption are needed in applications such as photonic devices. In this paper, an increase in absorption is achieved through plasmonic coupling of a nearby Au thin layer directly or through a spacer to the WS2 monolayer. The optical properties of the designed structures are investigated by the transfer matrix method in the visible wavelength region. In the structure consisting of a WS2 monolayer with Au and spacer layers, the absorption at 619 nm was increased to 61%. Sharp optical absorption as high as 40% for a large range of incidence angles in both polarizations was retained. Our study provides useful information for the design of WS2 monolayers in photonic devices for practical applications.
Optical phonons and their transformation in cylindrical wurtzite core-multishell nanowires with ternary mixed crystal effect
Authors: Wang J. X. , Qu Y. , Ban S. L.
Published: February 2020

The whole optical phonon spectrum of quasiconfined (CO), propagating (PR), and interface (IF) modes in wurtzite III-nitride cylindrical core-multishell nanowires (CMSNWs) is obtained based on the dielectric continuum and Loudon's uniaxial crystal models considering the ternary mixed crystal effect. A transfer matrix method calculation shows that there are six types of CO modes and one type of PR mode in a three-layered CMSNW. For any fixed component, only permitted types of CO modes exist in allowable frequency regions, while the PR modes appear only when components are almost the same in all layers, originating from anisotropic optical phonons in bulk wurtzite nitride. The whole spectrum reveals two mode transformations: one is between PR and IF modes by adjusting components in different layers; the other is continuous among five possible modes at any fixed component with connected frequency regions. The dispersion relations and corresponding electrostatic potentials of the whole optical phonon spectrum are helpful to understand the frequency-dependent electron–phonon interaction in the future. The analysis process can be extended to arbitrary nitride cylindrical CMSNWs for the modulation of optical phonon related properties.
Electron transfer and spin dynamics of the radical-pair in the cryptochrome from Chlamydomonas reinhardtii by computational analysis
Authors: Hong Gongyi , Pachter Ruth , Essen Lars-Oliver , Ritz Thorsten
Published: February 2020

In an effort to elucidate the origin of avian magnetoreception, it was postulated that a radical-pair formed in a cryptochrome upon light activation provided the basis for the mechanism that enables an inclination compass sensitive to the geomagnetic field. Photoreduction in this case involves formation of a flavin adenine dinucleotide (FAD)-tryptophan (TRP) radical-pair, following electron transfer within a conserved TRP triad in the cryptochrome. Recently, an animal-like cryptochrome from Chlamydomonas reinhardtii (CraCRY) was analyzed, demonstrating the role of a fourth aromatic residue, which serves as a terminal electron donor in the photoreduction pathway, resulting in the creation of a more distal radical-pair and exhibiting fast electron transfer. In this work, we investigated the electron transfer in CraCRY with a combination of free energy molecular dynamics (MD) simulations, frozen density functional theory, and QM/MM MD simulations, supporting the suggestion of a proton coupled electron transfer mechanism. Spin dynamics simulations discerned details on the dependence of the singlet yield on the direction of the external magnetic field for the [FAD•− TYRH•+] and [FAD•− TYR•] radical-pairs in CraCRY, in comparison with the previously modeled [FAD•− TRPH•+] radical-pair.
Lack of linear magnetoelectric effect in ferrimagnetic distorted honeycomb Ni4Nb2O9
Authors: Tailleur Elodie , Martin Christine , Damay Françoise , Fauth François , Maignan Antoine
Published: February 2020

M 4 A 2O9 transition metal oxides, with M a divalent cation and A Nb or Ta, that exhibit a structure derived from corundum constitute an interesting class of materials due to their possible magnetoelectric properties. The lack of a linear magnetoelectric effect in Ni4Nb2O9, unlike Mn4Nb2O9 or Co4Nb2O9, is explained by a comprehensive investigation, combining synchrotron x-ray and neutron diffraction with magnetization, dielectric, and polarization measurements. The m′m′m magnetic point group associated with the Pb′cn′ ferrimagnetic structure induced below 76 K by the orthorhombic Pbcn structure of Ni4Nb2O9 forbids indeed such an effect. The crystal structure and magnetic ground state of Ni4Nb2O9 are discussed and compared with those of magnetoelectric P3¯c1M4A2O9 compounds whose structure derives from corundum.
Non-Markov bond model for dynamic force spectroscopy
Authors: Bullerjahn Jakob Tómas , Sturm Sebastian , Kroy Klaus
Published: February 2020

Single-molecule force spectroscopy data are conventionally analyzed using a schematic model, wherein a molecular bond is represented as a virtual particle diffusing in a one-dimensional free-energy landscape. However, this simple and efficient approach is unable to account for the “anomalous” bond-breaking kinetics increasingly observed in force spectroscopy experiments and simulations, e.g., in the form of non-exponential distributions of bond lifetimes under constant load. Here, we show that such characteristic traits arise naturally in a rigorous extension of the one-dimensional theory that accounts for the transient dynamics of a generic set of coupled degrees of freedom. These “hidden modes” affect the reaction dynamics in various ways, depending on their relaxation spectrum and the loading protocol, giving rise, in particular, to apparent static and dynamic disorder. In two complementary asymptotic limits, we are able to find exact analytical expressions for pertinent experimental observables, such as the mean rupture force and the rupture–force distribution. Intriguingly, our asymptotic results become unconditionally exact at high loading rates, thus providing us with a microscopically consistent theory of rapid force spectroscopy that avoids the usual Markov assumption.
Heat transport with phonon–electron energy exchange in Bi2Te3 circular thin layers
Authors: Carlomagno I. , Sellitto A. , Cimmelli V. A.
Published: February 2020

At steady state, we determine the temperature profile in a circular thin layer surrounding an inner nanodevice that acts as a source of heat. The analytical solution, under suitable boundary conditions, is obtained by means of a two-temperature model, which establishes the balance laws governing the spatial distribution of temperatures and heat fluxes. The main results are displayed when the circular thin layer is made of Bi2Te3 and are discussed in view of the second law of thermodynamics.
The effect of hydrodynamics on the crystal nucleation of nearly hard spheres
Authors: Fiorucci Giulia , Coli Gabriele M. , Padding Johan T. , Dijkstra Marjolein
Published: February 2020

We investigate the effect of hydrodynamic interactions (HIs) on the crystal nucleation of hard-sphere colloids for varying supersaturations. We use molecular dynamics and stochastic rotation dynamics techniques to account for the HIs. For high supersaturation values, we perform brute force simulations and compute the nucleation rate, obtaining good agreement with previous studies where HIs were neglected. In order to access low supersaturation values, we use a seeding approach method and perform simulations with and without HIs. We compute the nucleation rates for the two cases and surprisingly find good agreement between them. The nucleation rate in both cases follows the trend of the previous numerical results, thereby corroborating the discrepancy between experiments and simulations. Furthermore, we investigate the amount of fivefold symmetric clusters (FSCs) in a supersaturated fluid under different physical conditions, following the idea that FSCs compete against nucleation. To this end, we explore the role of the softness of the pair interactions, different solvent viscosities, and different sedimentation rates in simulations that include HIs. We do not find significant variations in the amount of FSCs, which might reflect the irrelevance of these three features on the nucleation process.
Acceleration and trapping of fast ions in self-organized magneto-plasma structures in the dense plasma focus
Authors: Auluck S. K. H.
Published: February 2020

Recent research at the PF-1000 Dense Plasma Focus facility strongly suggests that the early part of neutron emission is caused by fast deuterons with energy on the order of ∼100 keV, having approximately equal axial and radial velocity, temporally coinciding with the occurrence of self-organized, bounded magneto-plasma structures, which remain trapped within the reaction zone for tens of transit times. The experimental evidence, predominantly qualitative in nature, does not clarify the nature and origin of the accelerating electric field responsible for high ion energy and of the magnetic field that might be confining the ions to the reaction zone except for the suggestion that they have toroidal and poloidal magnetic field components whose presence is revealed by magnetic probes. Current theories, conjectures, and models of plasma focus find it difficult to accommodate three-dimensional features of ion motion and magnetic field revealed by multiple experiments within their scope. This paper revisits the relevant experimental evidence and introduces a model that is deliberately non-quantitative in order to accommodate the qualitative nature of the available experimental evidence. The model leads to a functional form for the 3-dimensional distribution of magnetic field associated with the spontaneously self-organized magneto-plasma structures. This enables the discussion of properties of 3-dimensional trajectories of ions accelerated by electric fields induced during their growth. Many qualitative observations about the nature of neutron emission in Dense Plasma Focus and the observed phenomenology of plasma evolution can be understood in terms of this model in a unified manner. The model also helps conceive a new generation of diagnostic schemes targeted at getting quantitative information that is out of reach of currently available diagnostics.
Competition of noise and collectivity in global cryptocurrency trading: Route to a self-contained market
Authors: Drożdż Stanisław , Minati Ludovico , Oświȩcimka Paweł , Stanuszek Marek , Wa̧torek Marcin
Published: February 2020

Cross correlations in fluctuations of the daily exchange rates within the basket of the 100 highest-capitalization cryptocurrencies over the period October 1, 2015–March 31, 2019 are studied. The corresponding dynamics predominantly involve one leading eigenvalue of the correlation matrix, while the others largely coincide with those of Wishart random matrices. However, the magnitude of the principal eigenvalue, and thus the degree of collectivity, strongly depends on which cryptocurrency is used as a base. It is largest when the base is the most peripheral cryptocurrency; when more significant ones are taken into consideration, its magnitude systematically decreases, nevertheless preserving a sizable gap with respect to the random bulk, which in turn indicates that the organization of correlations becomes more heterogeneous. This finding provides a criterion for recognizing which currencies or cryptocurrencies play a dominant role in the global cryptomarket. The present study shows that over the period under consideration, the Bitcoin (BTC) predominates, hallmarking exchange rate dynamics at least as influential as the U.S. dollar (USD). Even more, the BTC started dominating around the year 2017, while other cryptocurrencies, such as the Ethereum and even Ripple, assumed similar trends. At the same time, the USD, an original value determinant for the cryptocurrency market, became increasingly disconnected, and its related characteristics eventually started approaching those of a fictitious currency. These results are strong indicators of incipient independence of the global cryptocurrency market, delineating a self-contained trade resembling the Forex.
Band structure, effective mass, and carrier mobility of few-layer h-AlN under layer and strain engineering
Authors: Cai Yao , Liu Yan , Xie Ying , Zou Yang , Gao Chao , Zhao Yan , Liu Sheng , Xu Hongxing , Shi Jian , Guo Shishang , Sun Chengliang
Published: February 2020

Wide bandgap two-dimensional semiconductors are of paramount importance for developing van der Waals heterostructure electronics. This work reports the use of layer and strain engineering to introduce the feasibility of two-dimensional hexagonal (h)-AlN to fill the scientific and application gap. We show that such one- to five-layer h-AlN has an indirect bandgap, tunable from 2.9 eV for a monolayer to ∼3.5 eV for multilayer structures, along with isotropic effective masses and carrier mobilities between zigzag and armchair directions. With an increase in the layer number to bulk AlN, the bandgap will experience a transition from an indirect gap to direct gap. Surprisingly, high room-temperature mobilities of electrons and holes (of the order of 1000 cm2 V−1 s−1) in a relaxed monolayer h-AlN system and widely adjustable effective masses and carrier mobilities in a different layer h-AlN are observed. In the presence of strain engineering, the bandgap decreases obviously with an increase in tensile strain; meanwhile, the isotropy and value of effective mass or carrier mobility in monolayer h-AlN can also be modulated effectively; the hole mobilities in the armchair direction, especially, will be enhanced dramatically. With a tunable bandgap, high carrier mobilities, and modifiable isotropy, our results indicate that few-layer h-AlN has potential applications in future mechano-electronic devices.
Optical and recombination properties of dislocations in cast-mono silicon from short wave infrared luminescence imaging
Authors: Ory Daniel , Hildebrandt Thibaud , Lombez Laurent
Published: February 2020

We demonstrate the use of the D1/D2 defect luminescence spectral range (1400 nm < λ < 1700 nm) of dislocations in cast-mono silicon to access geometrical tilt and opto-electronic recombination properties in their vicinity. The angle between dislocation and surface was determined thanks to the spatial asymmetry of the PL intensity in the regions close to the dislocations. Our optical model relies on the classical recombination–diffusion continuity equation as well as simple optical absorption and light propagation properties. It takes advantage of the optical transparency of silicon for wavelengths above 1400 nm. Carrier transport properties such as nonradiative lifetime around that location are also investigated. The model is discussed with a parameter study and the unicity of the extracted parameter set has been confirmed. As an example, we find out an angle of a selected dislocation pattern of about 25.4° with respect to the surface and an effective lifetime of 0.8–0.9 μs.
Thickness-dependent microstructural properties of heteroepitaxial (00.1) CuFeO2 thin films on (00.1) sapphire by pulsed laser deposition
Authors: Luo Sijun , Fluri Aline , Zhang Song , Liu Xue , Döbeli Max , Harrington George F. , Tu Rong , Pergolesi Daniele , Ishihara Tasumi , Lippert Thomas
Published: February 2020

Typical low-temperature frustrated triangular antiferromagnet CuFeO2 is attracting extensive interest due to its narrow-band-gap semiconductor properties. High-quality and impurity-free CuFeO2 epitaxial thin films would be preferable for fundamental studies on the physical and chemical properties. However, the heteroepitaxial growth of impurity-free CuFeO2 thin films has been a significant challenge due to its narrow formation window in the Cu–Fe–O system as well as the metastable nature of the Cu1+ cations. This work reports for the first time the fabrication and characterization of high-quality and impurity-free (00.1)-oriented CuFeO2 epitaxial thin films grown with relaxed interfaces on (00.1) sapphire substrates by pulsed laser deposition. Below the critical thickness of around 16 nm, the films exhibit a rhombohedral structure with relatively good crystalline quality where all Cu ions appear to be in the 1+ oxidation state, while the rocking curves display a narrow full width at half maximum of about 0.11°. Increasing the thickness, the (111)-oriented γ-Fe2O3 nanograins grow embedded in the CuFeO2 films. Here, an excess Fe3+-assisted growth mechanism is proposed to explain the iron oxide grain formation. This study provides insight into the heteroepitaxial growth of relaxed CuFeO2 thin films with high purity and crystalline quality as an ideal sample design to characterize the fundamental properties of this material in view of potential device applications.
Time-resolved Langmuir probe diagnostics of a bipolar high power impulse magnetron sputtering discharge
Authors: Hippler Rainer , Cada Martin , Hubicka Zdenek
Published: February 2020

High power impulse magnetron sputtering (HiPIMS) of a cobalt cathode in argon gas was investigated by time-resolved electrical (Langmuir) probe diagnostics and by time-integrated energy-resolved mass spectrometry. The HiPIMS discharge was operated with a bipolar pulsed power supply, providing a large negative voltage with a typical pulse width of 100 μs followed by a long positive pulse with a pulse width of about 310 μs. The time-resolved Langmuir probe results yield a small negative plasma potential in the negative pulse regime and a large positive floating potential and plasma potential in the positive pulse regime. The electron density is significantly reduced during the positive pulse regime. The probe results are supported by ion energy measurements.
Suppression of dislocation-induced spiral hillocks in MOVPE-grown AlGaN on face-to-face annealed sputter-deposited AlN template
Authors: Uesugi Kenjiro , Shojiki Kanako , Tezen Yuta , Hayashi Yusuke , Miyake Hideto
Published: February 2020

AlGaN films were grown on face-to-face annealed sputter-deposited AlN/sapphire (FFA Sp-AlN) templates via metalorganic vapor phase epitaxy (MOVPE), and the growth behavior of the AlGaN films was investigated. The sapphire substrates with small off-cut exhibited poor surface flatness of AlGaN grown on the FFA Sp-AlN templates owing to the formation of large hillock structures. To understand the origin of these hillock structures, the crystallinity and surface morphology of conventional fully MOVPE-grown AlN/sapphire (MOVPE-AlN) templates and the FFA Sp-AlN template were comprehensively studied. The screw- and mixed-type threading dislocation density of the FFA Sp-AlN template was estimated to be approximately 1.8 × 106 cm−2, which was two orders of magnitude lower than that of the MOVPE-AlN template. Consequently, the uniquely observed growth of the hillock structures in the FFA Sp-AlN templates was attributed to their low density of screw- and mixed-type threading dislocations. The large surface off-cut sapphire substrates suppressed the hillock structures on the FFA Sp-AlN templates. The improvement in surface flatness resulted in better optical properties of multiple quantum wells grown on the AlGaN layer. These results demonstrate a promising method for achieving highly efficient and cost effective AlGaN based deep ultraviolet light-emitting diodes.
Discharge mode transition in a Krypton-fed 1 A-class LaB6 cathode for low-power Hall thrusters for small satellites
Authors: Potrivitu G.-C. , Xu L. , Huang S. , Rohaizat M. W. A. B. , Xu S.
Published: February 2020

Thermionic cathodes are essential for the operation of various electrostatic propulsion devices. They strongly influence the performance and lifetime of the propulsion system. In this study, a 1 A-class LaB6 laboratory model hollow cathode has been tested with krypton in diode and triode configurations in order to assess the cathode discharge mode transition behavior. Measurements have been performed over a range of krypton mass flow rates (0.1, 0.15, and 0.21 mg/s, or 1.6, 2.4, and 3.4 sccm), keeper (0.1, 0.15, and 0.2 A), and anode currents (0.1–1 A) at a fixed cathode-to-anode distance. Seven criteria were used to distinguish between the spot and plume mode operations. The results show that the mode transition in low-current cathodes may be a nonlinear phenomenon, and only some of the existing mode transition criteria can be used to accurately predict the spot/plume discharge regions at low emission currents.
Resemblance between motile and magnetically actuated sperm cells
Authors: Khalil Islam S. M. , Magdanz Veronika , Simmchen Juliane , Klingner Anke , Misra Sarthak
Published: February 2020

The active flagellum propels a motile sperm cell by traveling bending waves. Here, we demonstrate that non-motile cells have the capacity to be wirelessly actuated by external magnetic fields and reveal insights into their propulsion characteristics. Partial coating of the sperm head with nanoparticle aggregates is achieved by electrostatic-based self-assembly. The coating enables propagation of helical traveling waves along the passive flagellum under the action of a periodic magnetic field. We compare the waveforms of active and passive flagellated motion and show noticeable asymmetry in the case of magnetically actuated cells, leading to lower linearity (LIN=VSL/VCL) of the taken pathway. The average curvature of the flagellar beat cycle is 10.4 ± 8.1 rad mm−1 (mean ± s.d.) for an active flagellum, whereas the curvature of a passive flagellum exhibits a linear increase (37.4 ± 18.1 rad mm−1) and decreases toward the distal end. We also show that the maximum amplitude of the bending wave occurs at the distal end of the active flagellum and at the middle of the passive flagellum. Our experiments also show the ability of the actuating field to control the rate of progression of the bending waves along the passive flagellum to match that of motile cells.
Long optical coherence times of shallow-implanted, negatively charged silicon vacancy centers in diamond
Authors: Lang Johannes , Häußler Stefan , Fuhrmann Jens , Waltrich Richard , Laddha Sunny , Scharpf Jochen , Kubanek Alexander , Naydenov Boris , Jelezko Fedor
Published: February 2020

The creation of single, negatively charged silicon vacancy (SiV−) centers in well-defined diamond layers close to the host surface is a crucial step for the development of diamond-based quantum optic devices with many applications in nanophotonics, quantum sensing, or quantum information science. Here, we report on the creation of shallow (10 nm below the surface), single SiV− centers in diamond using low energy Si+ ion implantation with subsequent high temperature annealing at 1500 °C. We show transition linewidths down to 99 MHz and narrow inhomogeneous distributions. Furthermore, we achieved a reduction of homogeneous linewidths by a factor of 2 after removing subsurface damage using oxygen plasma processing. These results not only give insights into the formation process of SiV− centers but also indicate a favorable processing method to fabricate shallow single quantum emitters in diamond perfectly suited for coupling to nanostructures on the diamond surface.
Bonding and thermal stability of cysteine on single-crystalline iron oxide surfaces and Pt(111)
Authors: Abdou Jasmin-Mathelda , Seidel Peter , Sterrer Martin
Published: February 2020

Model studies on the adsorption of simple amino acids on single-crystalline substrates provide the basis for understanding the interactions of more complex biomolecules with inorganic materials. In this study, the adsorption and thermal stability of cysteine on Pt(111) and on monolayer FeO(111)/Pt(111) and thick Fe3O4(111)/Pt(111) films have been investigated in ultrahigh vacuum by means of x-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and temperature-programmed desorption. At low adsorption temperature (160 K), cysteine stays intact on all studied surfaces. However, the thermal stability differs dramatically. Decomposition via dehydrogenation, decarbonylation/decarboxylation, and deamination starts already below room temperature on Pt(111). By contrast, adsorbed cysteine is stable up to 500 K on Fe3O4(111) and then gets oxidized in a redox reaction involving the Fe3O4 substrate. FeO(111)/Pt(111) is a special case, where decarbonylation of cysteine occurs below room temperature, which is most likely initiated by a structural modification and concomitant charge transfer at the Pt-FeO interface induced by the carboxyl group of the adsorbed cysteine. The experimental results suggest that cysteine binds to the surfaces with the carboxyl group on the iron oxides and with the carboxyl and amino groups on Pt(111).
Magnetohydrodynamic natural convection flow of a nanofluid due to sinusoidal surface temperature variations
Authors: Chandra Roy Nepal
Published: February 2020

We examine the natural convection flow that arises in an electrically conducting nanofluid due to the sinusoidal surface temperature variations along a vertical surface. The effect of thermal radiation is also incorporated. The reduced system of governing equations is solved using an efficient implicit finite difference method which is also known as the Keller box method. The results are presented in terms of the shear stress and the rate of heat transfer as well as the velocity and temperature profiles. In general, the amplitude of the undulation of the shear stress gradually decreases and that of the rate of heat transfer increases along the streamwise direction. The significant finding is that, with an increase in the volume fraction of nanoparticles, the shear stress diminishes, whereas the rate of heat transfer considerably increases. Due to the increase in the amplitude of oscillation of the surface temperature, conduction–radiation parameter, and surface temperature, a substantial increase is observed in both the shear stress and the rate of heat transfer. Contrary to this, the shear stress and the rate of heat transfer decrease with the increase in the magnetic field parameter. For any value of the relevant parameters, the use of nanoparticles in a pure fluid reduces the shear stress and enhances the rate of heat transfer. Moreover, when a nanofluid is used instead of pure fluid, the thicknesses of momentum and thermal boundary layers are found to increase, irrespective of the physical parameters.
Marine Ostracoda (Crustacea) from the Late Oligocene Gellibrand Marl, Otway Basin, Victoria, Australia
Authors: Eglington Col
Published: February 2020

A subsurface sample from Heywood-10 borehole, Otway Basin, Victoria, has provided the first ostracod assemblage of Oligocene age from the Gellibrand Marl (Heytesbury Group). Previous Gellibrand Marl ostracod assemblages were Miocene. This Late Oligocene assemblage of 384 specimens includes 50 species and subspecies from 34 genera across 18 families; 24 taxa are placed in open nomenclature. Of the taxa discussed, several appear to be new species but with too few specimens for them to be described as such. The reciprocal of Simpson’s Diversity Index was applied to assist assemblage comparisons. The Gellibrand Marl assemblage is larger, contains more families, genera and taxa but is less diverse than a smaller assemblage from the Early Oligocene Narrawaturk Formation (Nirranda Group) at the same location, and more diverse than an assemblage from the Early Oligocene/Ruwarung Member, South Australia. There are notable differences in the dominant taxa present in each assemblage. In the Gellibrand Marl, Pontocyprididae predominate; in Narrawaturk Formation, Cytheruridae and Xestoliberididae are most abundant; and in the South Australian assemblage, Bairdiidae by far the most numerous. This Gellibrand Marl collection has the characteristics of an at least partly allocthanous assemblage, the habitat a well-oxygenated mid-shelf environment. No cold or deep-water taxa are present.
Assessment of post-wildfire erosion risk and effects on water quality in south-western Australia
Authors: Blake David , Nyman Petter , Nice Helen , D'Souza Frances M. L. , Kavazos Christopher R. J. , Horwitz Pierre
Published: February 2020

Investigations of wildfire impact on water resources have escalated globally over the last decade owing to an awareness of climate-related vulnerabilities. Within Australia, research into post-wildfire erosion has focused on water supply catchments in the south-eastern region. Here, we examine post-wildfire erosion risk and its potential for water quality impacts in a catchment in south-western Australia. The catchment of the Harvey River, which drains from forested escarpments onto an agricultural coastal plain and into valuable coastal wetlands, was burnt by wildfire in 2016. The aims of this study were to determine erosion risk across contrasting landforms and variable fire severity, using the Revised Universal Soil Loss Equation (RUSLE), and to determine whether post-fire water quality impacts could be detected at permanent river monitoring stations located on the coastal plain. RUSLE outputs showed erosion hot-spots at intersections of steep terrain and high fire severity and that these areas were confined to forested headwaters and coastal dunes. Monthly water quality data showed conspicuous seasonal patterns, but that sampling frequency was temporally too coarse to pick up predicted event-related effects, particularly given that the pre-existing monitoring sites were distal to the predicted zone of contamination.
A stairheid rammy
Authors: McKay Fiona
Published: February 2020

This article explores the mediated representation of gender in the Scottish public sphere during the independence referendum in 2014. In particular, it focuses on a media sample drawn from the Scottish press that centres on two key political figures, Johann Lamont and Nicola Sturgeon, who took part in a televised debate during the campaign. Using critical discourse analysis, it looks at how language is used to construct overlapping discourses of gender in a specific cultural and national context. Findings show representations pivot on expectations that female politicians should embody a specific feminised style; and when gender norms appear to be violated, this is represented in negatively gendered terms. Though there is evidence of contestation of male-dominated politics, discourses still reify traditional gender norms and situate women as outsiders to the political sphere. This study shows how specific discursive frames can contribute to a cross-cultural practice of gendering women in politics.
Developing a mathematical model to predict energy expenditure while bouncing on a trampoline
Authors: Alexander Keith , Clement Tane , Draper Nick
Published: February 2020

Trampolining has become a popular recreational activity, but currently no method exists by which energy expenditure can be indirectly measured while bouncing. Therefore, the aim of this study was to produce a model to measure energy expenditure while bouncing on a trampoline. To achieve this, the study was completed in two stages. First, a model was developed which calculated the energy absorbed by the trampoline for a known weight. This was achieved using drop tests on a trampoline. Second, the efficiency of energy conversion while trampolining was measured. This involved healthy adults bouncing on a trampoline while energy expenditure was recorded using a gas analyser. The combined datasets from the two parts allowed the formation of a model which can predict energy expenditure while bouncing on a trampoline using only the user's weight as an input. This model can now be used with an on‐trampoline measurement method to track energy expenditure while jumping, thereby facilitating the use of trampolines for health and fitness.
Measurement of Spin Singlet-Triplet Qubit in Quantum Dots Using Superconducting Resonator*
Authors: Zhu Xing-Yu , Tu Tao , Guo Ao-Lin , Zhou Zong-Quan , Guo Guang-Can
Published: February 2020

The spin qubit in quantum dots is one of the leading platforms for quantum computation. A crucial requirement for scalable quantum information processing is the high efficient measurement. Here we analyze the measurement process of a quantum-dot spin qubit coupled to a superconducting transmission line resonator. Especially, the phase shift of the resonator is sensitive to the spin states and the gate operations. The response of the resonator can be used to measure the spin qubit efficiently, which can be extend to read out the multiple spin qubits in a scalable solid-state quantum processor.
Generation of 88 as Isolated Attosecond Pulses with Double Optical Gating*
Authors: Wang Xiaowei , Wang Li , Xiao Fan , Zhang Dongwen , Lü Zhihui , Yuan Jianmin , Zhao Zengxiu
Published: February 2020

Isolated attosecond pulses with a duration of 88 as are generated in the spectral range of 29–72 eV using double optical gating technique. The gate width is set to be shorter than half the optical cycle to avoid carrier envelop phase stabilization of the 4.2 fs driving laser pulses centered at 800 nm. The attosecond pulse duration is measured with the technique of frequency resolved optical gating for complete reconstruction of attosecond bursts.