bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic-scale topography of rutile TiO2(110) in aqueous solutions: A study involving frequency-modulation atomic force microscopy
Authors: Xue Shengkai , Sasahara Akira , Onishi Hiroshi
Published: February 2020

The interfaces between metal oxides and liquids represent the next frontier in the study of oxide chemistry. In this work, (110)-oriented rutile TiO2 wafers were annealed in oxidative atmospheres and immersed in aqueous KCl solutions of pH 3, 6, and 11. Topographic imaging of the TiO2 wafers was carried out in solution via atomic force microscopy using the frequency-modulation force detection technique. Crystalline terraces of 100 nm in width were observed with no sign of solution-induced etching. In a pH-6 solution, ridges parallel to the [001] axis with trenches in between were observed and assigned to the rows of oxygen anions protruding from the surface plane to the solution. Individual anions were further resolved in the ridges, revealing atomic-size protrusions located on the (1 × 1) meshes of the (110) truncation. The topography in an acidic solution (pH 3) was similar to that observed in a neutral solution and could be interpreted as protruding oxygen anions covered partially by protons. In a basic solution with pH 11, qualitatively different features were observed; atomic-size swellings formed a p(2 × 1) superstructure covering the surface, which was hypothesized to be Ti–OH− on five-fold coordinated Ti cations in the surface plane. These results show the feasibility of advanced atomic force microscopy for probing metal-oxide surfaces submerged in liquids.
Mechanical characterization of the nitrocellulose-based visco-hyperelastic binder in polymer bonded explosives
Authors: Iqbal M. , Li-Mayer J. Y. S. , Lewis D. , Connors S. , Charalambides M. N.
Published: February 2020

A rheological constitutive model is required to characterize the behavior of a nitrocellulose-based material used as a binder in polymer bonded explosives. The behavior of the binder is extremely important as it heavily influences the mechanical response of the polymer composite; this is due to the binder having stiffness five orders of magnitude lower than the stiffness of the explosive crystals. Determination of the material model parameters is not straightforward; a constitutive law that will capture the pronounced time-dependent, temperature-dependent, and highly non-linear, large deformation response of this material is required. In this study, the material properties of the binder are determined using constant shear strain rate, shear stress relaxation, and monotonic tensile test results obtained over a wide range of temperature and strain rates. A visco-hyperelastic model is parameterized using the derived test data. In addition, recommendations are made regarding accurate data derived from rheological testing on such materials falling in the soft solid rather than the complex fluid domain.
Limits of adiabatic clocking in quantum-dot cellular automata
Authors: Retallick Jacob , Walus Konrad
Published: February 2020

Ultimate bounds on the maximum operating frequency of networks of Quantum-dot Cellular Automata (QCA) devices have yet to be established. We consider the adiabaticity of such networks in the two-state approximation where clocking is achieved via modulation of the interdot tunneling barriers. Estimates of the maximum operating frequency that would allow a 99% probability of observing the correct logical output are presented for a subset of the basic components used in QCA network design. Simulations are performed both in the coherent limit and for a simple dissipative model. We approach the problem of tunnel-based clocking from the perspective of quantum annealing and present an improved clocking schedule allowing for faster operation. Using an analytical solution for driven QCA wires, we show that the maximum operating frequency in the coherent limit falls off with the square of the wire length, potentially limiting the size of clocked regions.
Superlattices of covalently cross-linked 2D materials for the hydrogen evolution reaction
Authors: Rao C. N. R. , Pramoda K. , Saraswat Aditi , Singh Reetendra , Vishnoi Pratap , Sagar Nidhish , Hezam Abdo
Published: February 2020

Amongst the recent developments in 2D materials, van der Waals heterostructures formed by depositing a monolayer or few-layers of a 2D material on a monolayer or on few-layers of the same or another 2D material have attracted great attention. As an alternative to such heterostructures, we have carried out investigations on covalently cross-linked heterostructures by chemical coupling of layers of the same or different 2D materials. This effort has met with success, with typical systems studied by us being graphene–graphene, graphene–MoS2, C3N4–MoS2, borocarbonitride–MoS2, and phosphorene–MoS2. We describe these structures to demonstrate how the covalent cross-linking strategy yields novel 2D nanocomposites. These structures exhibit interesting gas adsorption properties as well as noteworthy hydrogen evolution reaction (HER) activity. The phosphorene–MoS2 nanocomposite is found to exhibit superior photocatalytic HER activity. The most interesting nanocomposite is BCN–MoS2 which exhibits electrochemical HER activity comparable to platinum, thus providing a new and novel example of metal-free catalysis.
Experimental observation and numerical investigation of filamentary structures in magnetized plasmas
Authors: Menati Mohamad , Rasoolian Behnam , Thomas Edward , Konopka Uwe
Published: February 2020

Filamentary structures in low-pressure, low-temperature plasmas are produced when strong magnetic fields are applied parallel to the electric field defined by parallel electrodes. Filamentary structures are regions within the plasma that have distinct properties such as optical brightness and extend along the magnetic field lines. In our experiments, an argon, radio frequency discharge is exposed to a strong background magnetic field in the magnetized dusty plasma experiment at Auburn University. Different forms of filamentary structures emerge in the plasma such as columns, target, or spiral-like structures. To investigate the origin and the characteristics of these patterns, we have developed a three-dimensional fluid model that can reproduce the experimental observations which enables us to investigate the underlying mechanisms of the filamentation process.
Reversible oxidation–reduction of epitaxial iron oxide films on Pt(111): Magnetite–hematite interconversion
Authors: Freindl Kinga , Wojas Joanna , Kwiatek Natalia , Korecki Józef , Spiridis Nika
Published: February 2020

We studied magnetite–hematite–magnetite transformations in an ultrathin epitaxial film on Pt(111) using surface sensitive and bulk sensitive methods. At initial oxidation stages at elevated temperature (810 K), a 5-nm thick magnetite Fe3O4(111) film became non-stoichiometric toward maghemite and then showed the first signs of hematite phase formation under an oxygen exposure of 3 × 103 L. Finally, under 2 × 104 L, the film fully transformed to hematite α-Fe2O3(0001), maintaining a high single-crystal quality. A comparison of the conversion electron Mössbauer spectra and low energy electron diffraction pattern showed that at intermediate oxidation stages, hematite dominated at the surface, whereas a spinel phase was still observed in the deeper layers. The magnetite–hematite conversion was fully reversed by annealing under ultra-high vacuum at temperatures exceeding 600 K, and despite a change in morphology, the magnetite film preserved the original crystal structure and orientation.
SquidLab—A user-friendly program for background subtraction and fitting of magnetization data
Authors: Coak Matthew J. , Liu Cheng , Jarvis David M. , Park Seunghyun , Cliffe Matthew J. , Goddard Paul A.
Published: February 2020

We present an open-source program free to download for academic use with a full user-friendly graphical interface for performing flexible and robust background subtraction and dipole fitting on magnetization data. For magnetic samples with small moment sizes or sample environments with large or asymmetric magnetic backgrounds, it can become necessary to separate background and sample contributions to each measured raw voltage measurement before fitting the dipole signal to extract magnetic moments. Originally designed for use with pressure cells on a Quantum Design MPMS3 SQUID magnetometer, SquidLab is a modular object-oriented platform implemented in Matlab with a range of importers for different widely available magnetometer systems (including MPMS, MPMS-XL, MPMS-IQuantum, MPMS3, and S700X models) and has been tested with a broad variety of background and signal types. The software allows background subtraction of baseline signals, signal preprocessing, and performing fits to dipole data using Levenberg–Marquardt non-linear least squares or a singular value decomposition linear algebra algorithm that excels at picking out noisy or weak dipole signals. A plugin system allows users to easily extend the built-in functionality with their own importers, processes, or fitting algorithms. SquidLab can be downloaded, under Academic License, from the University of Warwick depository (wrap.warwick.ac.uk/129665).
Influence of spontaneous curvature on the line tension of phase-coexisting domains in a lipid monolayer: A Landau-Ginzburg model
Authors: Rufeil Fiori Elena , Downing Rachel , Bossa Guilherme Volpe , May Sylvio
Published: February 2020

The line tension between two coexisting phases of a binary lipid monolayer in its fluid state has contributions not only from the chemical mismatch energy between the two different lipid types but also from the elastic deformation of the lipid tails. We investigate to what extent differences in the spontaneous curvature of the two lipids affect the line tension. To this end, we supplement the standard Landau-Ginzburg model for the line tension between coexisting phases by an elastic energy that accounts for lipid splay and tilt. The spontaneous curvature of the two lipids enters into our model through the splay deformation energy. We calculate the structure of the interfacial region and the line tension between the coexisting domains numerically and analytically, the former based on the full non-linear model and the latter upon employing an approximation in the free energy that linearizes the resulting Euler-Lagrange equations. We demonstrate that our analytical approximation is in excellent agreement with the full non-linear model and use it to identify relevant length scales and two physical regimes of the interfacial profile, double-exponential decay, and damped oscillations. The dependence of the line tension on the spontaneous curvatures of the individual lipids is crucially dependent on how the bulk phases are affected. In the special case that the bulk phases remain inert, the line tension decreases when the difference between the spontaneous curvatures of the two lipid types grows.
Stability investigation of a cryo soft x-ray microscope by fiber interferometry
Authors: Kördel M. , Arsana K. G. Y. , Hertz H. M. , Vogt U.
Published: February 2020

We present a stability investigation of the Stockholm laboratory cryo soft x-ray microscope. The microscope operates at a wavelength of 2.48 nm and can image biological samples at liquid-nitrogen temperatures in order to mitigate radiation damage. We measured the stability of the two most critical components, sample holder and optics holder, in vacuo and at cryo temperatures at both short and long time scales with a fiber interferometer. Results revealed vibrations in the kHz range, originating mainly from a turbo pump, as well as long term drifts in connection with temperature fluctuations. With improvements in the microscope, earlier stability issues vanished and close-to diffraction-limited imaging could be achieved. Moreover, our investigation shows that fiber interferometers are a powerful tool in order to investigate position-sensitive setups at the nanometer level.
3-dimensional nucleation of Fe oxide induced by a graphene buffer layer
Authors: Lodesani Alessandro , Picone Andrea , Brambilla Alberto , Finazzi Marco , Duò Lamberto , Ciccacci Franco
Published: February 2020

Shaping the morphology of oxide nanolayers is of paramount importance in tailoring their physical and chemical properties. Here, the influence of a two dimensional graphene buffer layer on the growth of Fe oxide has been investigated by comparing the oxide deposition on a Ni(111) and a graphene/Ni(111) substrate. Scanning tunneling microscopy images acquired at a mesoscopic scale indicate that Fe oxide grows layer-by-layer on the bare Ni(111) surface, while the nucleation of three-dimensional clusters is induced by graphene. Atomically resolved images reveal that Fe oxide adopts an in-plane lattice constant similar to that of the FeO(111) surface when deposited on Ni(111) and graphene/Ni(111), indicating in both cases, a weak interaction between the overlayer and the substrate. Accordingly, it is suggested that the different growth mode is mainly driven by the graphene-induced lowering of the substrate surface free energy.
Extension of the force-matching method to coarse-grained models with axially symmetric sites to produce transferable force fields: Application to the UNRES model of proteins
Authors: Liwo Adam , Czaplewski Cezary
Published: February 2020

The force-matching approach to coarse graining, in which the forces that act on site centers are fitted to the respective average forces computed from all-atom molecular dynamics simulations, provides a link between coarse-grained and all-atom molecular dynamics. In the existing implementations, radial site–site interaction potentials are assumed, thus precluding extensive coarse-graining that usually requires anisotropic potentials. In this work, we extended the force-matching approach to coarse-grained models with axially symmetric sites and implemented it to the UNRES model of polypeptide chains developed in our laboratory, in which the only interaction sites are united peptide groups and united side chains, the α-carbon atoms serving as anchor points. The optimizable parameters were those of the UNRES energy function and not whole potential profiles, which provide better transferability. We tested the implementation with the 20-residue tryptophan-cage miniprotein, selected as the training protein, starting from the NEWCT-9P variant of UNRES. The reference forces were obtained from implicit- and explicit-solvent simulations. Using a target function composed of a force-matching term and a maximum-likelihood term that drives the force field at reproducing the NMR-determined conformational ensembles at three selected temperatures, force fields were obtained which did not produce site–site clashes for the structures simulated with all-atom molecular dynamics with AMBER, and modeled the structures of α-helical proteins with resolution comparable to that of the NEWCT-9P force field. The new force fields also produced the free-energy landscapes of tryptophan cage similar to those obtained from the all-atom molecular dynamics runs.
An experimental model for pressure drop evaluation in a stenosed coronary artery
Authors: Freidoonimehr Navid , Chin Rey , Zander Anthony , Arjomandi Maziar
Published: February 2020

Non-invasive measurement of pressure drop has great clinical significance for the treatment of coronary artery diseases. The objective of this study is to develop a relationship that can estimate pressure drop in a stenosed coronary artery model as a function of different parameters such as blood viscosity, artery length and diameter, flow rate and flow profile, and shape and degrees of stenosis. Experimental pressure measurements from a wide range of degrees of stenosis and critical simplified geometries of stenosis along with different unsteady flow profiles are employed to evaluate the pressure drop equation. To calculate the blockage term of the pressure drop, several experimental cases are investigated, and the results show that the blockage factor is strongly dependent on the shape and degree of stenosis. Furthermore, different unsteady flow profiles are applied to calculate the pulsatile pressure drop term, and it is found that the pulsatility parameter is not a function of the flow profile or the shape of the stenosis. However, it is only a function of the degree of stenosis. To test the validity of the developed equation, pressure drops through stenosed coronary artery models with the real physiological flow profile of the left and right coronary arteries were predicted and compared with the experimental measurements. The proposed equation is able to determine the pressure drop inside a stenosed coronary artery non-invasively using the measurement of the flow profile inside the artery as well as the images of the stenosed coronary artery obtained based on the non-invasive methods.
Sensitivity of nonequilibrium Casimir forces on low frequency optical properties toward chaotic motion of microsystems: Drude vs plasma model
Authors: Tajik F. , Masoudi A. A. , Babamahdi Z. , Sedighi M. , Palasantzas G.
Published: February 2020

Here, we investigate the sensitivity of nonequilibrium Casimir forces to optical properties at low frequencies via the Drude and plasma models and the associated effects on the actuation of microelectromechanical systems. The stability and chaotic motion for both autonomous conservative and nonconservative driven systems were explored assuming good, e.g., Au, and poor, e.g., doped SiC, interacting conductors having large static conductivity differences. For both material systems, we used the Drude and plasma methods to model the optical properties at low frequencies, where measurements are not feasible. In fact, for the conservative actuating system, bifurcation and phase space analysis show that the system motion is strongly influenced by the thermal nonequilibrium effects depending on the modeling of the optical properties at low frequencies, where also the presence of residual electrostatic forces can also drastically alter the actuating state of the system, depending strongly on the material conductivity. For nonconservative systems, the Melnikov function approach is used to explore the presence of chaotic motion rendering predictions of stable actuation or malfunction due to stiction on a long-term time scale rather impossible. In fact, the thermal effects produce the opposite effect for the emerging chaotic behavior for the Au–Au and SiC–SiC systems if the Drude model is used to model the low optical frequencies. However, using the plasma model, only for the poor conducting SiC–SiC system, the chance of chaotic motion is enhanced, while for the good conducting Au–Au system, the chaotic behavior will remain unaffected at relatively short separations (<2 μm).
Solid-state cooling by stress: A perspective
Authors: Mañosa Lluís , Planes Antoni
Published: February 2020

Materials with both giant and colossal mechanocaloric effects together with giant electrocaloric and magnetocaloric materials are expected to replace harmful fluids in more efficient and environmentally friendly refrigeration and heat pumping technologies. While mechanocaloric materials have only received attention in the last decade, they have already shown better caloric performances than their magnetic and polar counterparts. In particular, the recent discovery of colossal barocaloric and elastocaloric materials opens up bright perspectives for this class of materials. We envisage great promise in the use of mechanocaloric materials for future energy applications.
On a simple model that explains inversion of a self-propelled rotor under periodic stop-and-release-operations
Authors: Koyano Yuki , Kitahata Hiroyuki , Nakata Satoshi , Gorecki Jerzy
Published: February 2020

We propose a simple mathematical model that describes the time evolution of a self-propelled object on a liquid surface using variables such as object location, surface concentration of active molecules, and hydrodynamic surface flow. The model is applied to simulate the time evolution of a rotor composed of a polygonal plate with camphor pills at its corners. We have qualitatively reproduced results of experiments, in which the inversion of rotational direction under periodic stop-and-release-operations was investigated. The model correctly describes the probability of the inversion as a function of the duration of the phase when the rotor is stopped. Moreover, the model allows to introduce the rotor asymmetry unavoidable in real experiments and study its influence on the studied phenomenon. Our numerical simulations have revealed that the probability of the inversion of rotational direction is determined by the competition among the transport of the camphor molecules by the flow, the intrinsic asymmetry of the rotor, and the noise amplitude.
Acoustics-driven vortex dynamics in channel branches with round intersections: Flow mode transition and three-dimensionality
Authors: Wang Peng , He Li , Liu Yingzheng
Published: February 2020

A combined experimental and large eddy simulation study was conducted to investigate acoustics-driven vortex dynamics inside channel branches with round intersections. The underlying flow mode transition and intensified flow three-dimensionality, which are closely related to the Coanda effect at round intersections, were comprehensively demonstrated. A dynamic pressure transducer array was first used to establish the relationship of the excited acoustic pressure pulsations to the channel-branch intersection radius (r) and the mainstream Reynolds number. In complementary simulations, three configurations with r/D = 0, 0.2, and 0.4 (where D is the short edge of the side-branch) were selected for demonstration. First, the simulated results were well validated in terms of acoustic pressure pulsations and phase-dependent flow fields. Subsequent analysis of the time-averaged and statistical flow characteristics revealed the existence of significantly intensified flow fluctuations inside the round channel branches having r/D = 0.2 and 0.4. Next, the proper orthogonal decomposition analysis was conducted to extract the dominant flow modes and to identify the energy transition from the streamwise vortex-shedding mode to vertical flow-oscillation mode. To this end, the influence of flow-mode transition on the phase-dependent flow fields was further investigated. The intensified branch-flow streaks resulted in a channel flow transition from synchronous convection of co-rotating vortex pairs into alternating convection of a single large-scale vortex, yielding a stronger flapping motion of the mainstream flow. Finally, the intensified flow three-dimensionality, presented by the essential spanwise Reynolds shear stresses inside the round channel branches, was found to relate to the strong turbulent mixing process caused by the flapping mainstream flow and the vertical branch flow oscillation. These findings are of great significance for industrial pipeline design and optimization.
Extraordinary magnetoresistance in encapsulated monolayer graphene devices
Authors: Zhou Bowen , Watanabe K. , Taniguchi T. , Henriksen E. A.
Published: February 2020

We report a proof-of-concept study of extraordinary magnetoresistance (EMR) in devices of monolayer graphene encapsulated in hexagonal boron nitride having metallic edge contacts and a central metal shunt. Extremely large EMR values, MR=(R(B)−R0)/R0∼105, are achieved in part because R0 approaches or crosses zero as a function of the gate voltage, exceeding that achieved in high mobility bulk semiconductor devices. We highlight the sensitivity, dR/dB, which in two-terminal measurements is the highest yet reported for EMR devices and in particular exceeds previous results in graphene-based devices by a factor of 20. An asymmetry in the zero-field transport is traced to the presence of pn-junctions at the graphene-metal shunt interface.
The effect of rare-earth substitution on the Debye temperature of inorganic phosphors
Authors: Hariyani Shruti , Duke Anna C. , Krauskopf Thorben , Zeier Wolfgang G. , Brgoch Jakoah
Published: February 2020

In the quest to predict photoluminescent efficiency in rare-earth substituted inorganic phosphors, research has shown that materials consisting of ordered, rigid crystal structures tend to possess the highest photoluminescent quantum yields. A compound's Debye temperature (ΘD), which can be calculated using ab initio calculations, is an ideal proxy for quantitatively comparing structural rigidity among different inorganic compounds, allowing potentially efficient phosphors to be selected from large crystal structure databases. However, the high computational cost of these calculations limits estimating ΘD for unsubstituted host crystal structures only. It is assumed that the low substitution concentration of the rare-earth luminescent center does not significantly influence a material's Debye temperature. This work evaluates the validity of this approximation by examining the effect of luminescent center substitution on a host structure's ΘD. Two well-known phosphors, (Y1–xCex)3Al5O12 (x = 0 − 0.05) and Ba1-δEuδMgAl10O17 (δ = 0 − 0.15), were synthesized with varying rare-earth concentrations, while ΘD was computationally estimated and then determined by ultrasonic pulse-echo speed-of-sound and low-temperature heat capacity measurements. The ensuing results provide key implications for using ΘD as a proxy for structural rigidity in substituted inorganic compounds.
Effect of aging time on the viscoelastic properties of amphiphilic polymer-polyacid supramolecular solution
Authors: Zhang Xiangfeng , Shan Xiuhua , Wang Fang , Yang Hongbin , Zhou Bobo , Jiang Haizhuang , Kang Wanli , Sarsenbekuly Bauyrzhan
Published: February 2020

An amphiphilic polymer-based supramolecular system was formulated by exploring the electrostatic interactions between the cationic amphiphilic polymer and polyacid. The effect of aging time on the viscoelastic properties, salt and temperature tolerance, shear resistance, and viscosity recovery of the system was explored by means of rheological measurements. The intrinsic relationship between the viscoelasticity of the system at different aging times and their dynamic growth was studied by macro-rheological and optical micro-rheological methods. The results show that under the influence of various factors, the viscoelastic properties of the supramolecular system increase significantly with aging. Optical micro-rheological studies demonstrated that the viscoelasticity of the system continues to increase over a period of 30 days. After aging, the viscoelastic results indicate the formation of a strong gel. This study clearly demonstrates that the aging time is a key factor that should be considered in the formulation of supramolecular systems formed by the electrostatic interaction between the cationic amphiphilic polymer and polyacid.
Researchers developed an open-source, user-friendly program for SQUID data processing
Authors: Bandari Anashe
Published: February 2020

SquidLab is an open-source program with the primary objective of simplifying and customizing magnetic background subtraction in SQUID data.
Euler-Lagrange method extends research on how bubbles reduce ship drag
Authors: Mandel Savannah
Published: February 2020

In a numerical study, the Euler-Lagrange method and a two-way coupled algorithm overcome previous challenges in bubble drag reduction study.
Interference microscopy study of the preplasma formed on an iron target surface exposed to high-power femtosecond laser pulses
Authors: Sitnikov D.S. , Ovchinnikov A.V. , Ashitkov S.I.
Published: February 2020

The characteristic scale of spread of the plasma formed on the surface of a bulk iron target irradiated by a femtosecond laser pulse with an intensity of 1016 W cm−2 is measured by time-resolved interference microscopy using femtosecond pulses emitted by a Cr : forsterite laser system with an intensity contrast of 107. The chosen technique is demonstrated to be efficient in such measurements. It is shown experimentally that, as a result of laser pulse impact, the displacement of a plasma layer with a density exceeding critical does not exceed 30 nm.
QR-code optical encryption in the scheme with spatially incoherent illumination based on two micromirror light modulators
Authors: Evtikhiev N.N. , Krasnov V.V. , Kuzmin I.D. , Molodtsov D.Yu. , Rodin V.G. , Starikov R.S. , Cheremkhin P.A.
Published: February 2020

An optical encryption scheme with spatially incoherent illumination based on two micromirror light modulators has been experimentally implemented for the first time. Currently, such modulators are the fastest tools for spatio-temporal light modulation; their high frame rates provide possibilities for developing optical encryption systems with a bandwidth of several gigabites per second.
Control over pulsed operation modes of an erbium-doped fibre laser passively mode-locked via nonlinear polarisation rotation
Authors: Volkov I.A. , Kamynin V.A. , Itrin P.A. , Ushakov S.N. , Nishchev K.N. , Tsvetkov V.B.
Published: February 2020

We have experimentally demonstrated the possibility of controlling pulse generation modes of an erbium-doped fibre ring laser operating in the anomalous dispersion regime and passively mode-locked via nonlinear polarisation rotation. It has been shown that individual adjustment of the pump power and intracavity polarisation controllers leads to changes in pulse generation mode, without changing the cavity. We have evaluated the key spectral, temporal and energetic characteristics of the observed pulse generation modes.
Tunable semiconductor laser with two acousto-optic tunable filters in its external cavity
Authors: Magdich L.N. , Chamorovskiy A.Yu. , Shidlovsky V.R. , Shramenko M.V. , Yakubovich S.D.
Published: February 2020

We report a laser with a linear external cavity containing a near-IR injection semiconductor optical amplifier as a gain element and two acousto-optic tunable filters (AOTFs) with quasi-collinear interaction of acoustic and light waves. At identical frequencies of RF signals that control the filters and ensure compensation for the Doppler frequency shift of light passing through the AOTFs, the steady-state laser emission linewidth can be reduced to about 25 MHz, which is almost three orders of magnitude smaller than that in the case of one filter (20 GHz). The position of the emission line, which remains narrow, slowly fluctuates within a spectral range about 3 GHz wide, which seems to be due to the large length of the external cavity and insufficient thermal stabilization of its components. This does not prevent us from obtaining light with a large coherence length. In emission wavelength sweep mode, the instantaneous emission linewidth increases with tuning rate, reaching 0.022 nm (8.8 GHz) at the highest tuning rate: 104 nm s−1. In the case of automatic control over the output optical power at a level of 3 mW, the tuning range is 815 – 875 nm. Such instruments are of practical interest for optical coherence tomography, spectroscopy, optical metrology, and other application areas.
Heating of aqueous suspensions of silicon nanoparticles by a 808-nm diode laser for application in local photohyperthermia
Authors: Oleshchenko V.A. , Bezotosnyi V.V. , Timoshenko V.Yu.
Published: February 2020

3D simulation of the distribution of thermal fields in aqueous suspensions of silicon nanoparticles upon irradiation by a high-power 808-nm laser diode operating in cw and quasi-cw repetitively pulsed regimes is performed. It is shown that irradiation by a repetitively pulsed laser with a peak power of 10 W and a pulse duration of 300 ms can form a region with a maximum temperature exceeding 42 °C, which is promising for application in cancer photohyperthermia for local heating of biotissues at a given depth.
Preference of Boer goats for Namibian native forage legumes and Lucerne (Medicago sativa)
Authors: Thamina D. N. , Kahumba A. , Shipandeni M. N. T. , Lutaaya E. , Mpofu I. D. T.
Published: February 2020

The objective of this study was to determine the relative palatability of four native forage legumes (Otoptera burchellii, Crotalaria argyraea, Crotalaria podocarpa and Vigna lobatifolia) in comparison with each other and with Lucerne (Medicago sativa). Eight weaned Boer goats aged 6 months and weighing 25.2 ± 4.9 kg were grouped by sex, and then randomly allocated to individual pens. Goats were simultaneously offered 100 g of each of the four native legumes and 600 g of M. sativa (as-is basis) over a 10-day period. Grass hay (Cenchrus ciliaris), fresh water and mineralised salt licks were available at all times. Grass hay was given to allow diet mixing and possibly ameliorate any undesirable effects, such as bloat, due to feeding on legumes alone. The percentage of each species consumed of that offered was associated (P < 0.001) with legume species, day and legume × day interaction. Over 95% of the O. burchellii, V. lobatifolia and Lucerne offered were consumed from Days 1 to 10. The amounts of Crotalaria spp. consumed fluctuated widely in the first 4 days, but increased thereafter to >95% of that offered. This study demonstrated that hay of all the four native forage legume hays were palatable to Boer goats, with the inferred ranking being: (Lucerne, V. lobatifolia) > O. burchellii > Crotalaria spp. Further studies are required to investigate the productivity of goats feeding on these native forage legumes, which have potential for use in marginal lands.
Genetic correlations and trends for traits of economic importance in dairy buffalo
Authors: da Silva Vilela Ranielle Nogueira , Sena Thomaz Marques , Aspilcueta-Borquis Rusbel Raul , de Oliveira Seno Leonardo , de Araujo Neto Francisco Ribeiro , Scalez Daiane Cristina Becker , Tonhati Humberto
Published: February 2020

Context
The planning and execution of selection programs requires estimates of the genetic correlations between traits. As genetic change is achieved for a given trait, it is important to consider possible genetic changes for other traits. Understanding the magnitude and direction of genetic correlations can assist in selection decisions.

Aims
The aim of the present study was to estimate the genetic correlations of reproductive traits with productive traits and with percentages of fat and protein in the milk of dairy buffalo. Additionally, genetic trends were estimated for the traits under study over the years.

Methods
Data from 11530 complete lactations of 3431 female buffalo were used. The following traits were analysed: milk, fat and protein yields; percentages of fat and protein; age at first calving; and calving interval. The (co)variance components were estimated by Bayesian inference in multi-trait analyses, considering a linear animal model. To calculate the genetic trends, the average annual genetic values were regressed on the year of birth.

Key results
The means of genetic correlations estimated between reproductive (age at first calving and calving interval) and productive (milk, fat and protein yields) traits were positive, but of moderate to low magnitude. The association between the reproductive and milk quality (fat and protein percentages) traits were negative and of low magnitude. Genetic trends for the productive traits were positive (5.25 ± 0.63, 0.15 ± 0.034 and 0.09 ± 0.038 kg/year for milk, fat and protein yields respectively). Genetic trends for the reproductive traits of age at first calving and calving interval increased by 0.47 ± 0.09 and 0.48 ± 0.10 days/year respectively. In terms of milk quality, however, the percentages of fat and protein decreased by 0.016 ± 0.003 and 0.011 ± 0.001%/year respectively.

Conclusions
Genetic gains in productive traits may elevate the number of days at first calving and extend the calving interval, in addition to leading to the production of milk of lower quality.

Implications
The use of a multi-trait selection index is an alternative, as it combines information from different sources, such that an optimal selection criterion can be achieved over time by virtue of its emphasis on appropriate weighting for all traits.
Building capacity in primary health care to respond to the needs of asylum seekers and refugees in Melbourne, Australia: the 'GP Engagement' initiative
Authors: Timlin Mark , Russo Alana , McBride Jacquie
Published: February 2020

Asylum seekers and refugees experience poorer health than the broader Australian population. Universal primary healthcare services play an integral role in supporting and optimising the health and wellbeing of these communities. However, clinical-level issues frequently compromise the quality of care provided to these groups. The ‘GP Engagement’ initiative, implemented in the south-eastern region of Melbourne, aimed to build capacity within universal primary health care to respond to the needs of asylum seekers and refugees. This involved engaging general practice clinics, resourcing them with tools and frameworks, and undertaking collaborative problem-solving on refugee issues. Evaluation methods included: rigorous record keeping; pre- and post-practice assessments guided by a self-reported ‘12-Point Checklist’; and participant feedback. Findings from 57 participating health professionals indicated changes in the way that GPs work with asylum seekers and refugees. ‘GP Engagement’ suggests that it is possible to build primary healthcare responsiveness to asylum seekers and refugees through a strategic regional approach that is firmly grounded in evidence-based practice and considerate of the requirements and constraints of GPs.
Iran–US Public Health Cooperative Organization (PHCO): Education, Healthcare, and Health Services in the Southwest of Iran (Fars), 1950–60
Authors: Heidari Soleyman
Published: February 2020

Fars is among the largest provinces of Iran that received the most technical assistance from the American economic delegation in the 1950s. After settling in the province and during ten years of activity, the American delegation provided technical assistance in the fields of health engineering, health education, preventive medicine, nursing, medical services, and medical education. This paper explains how the technical assistance of US personnel contributed to the general health of the Fars province. The findings of this research show that after the formation of the Public Health Cooperative Organization (PHCO) in 1950, not only did most of the cities and villages of this province began to enjoy safe drinking water, but also public health improved. Additionally, the birth of children with disabilities and the spread of infectious diseases such as malaria and trachoma declined by means of preventive medicine centers and health education.
Dispersible chitosan particles showing bacteriostatic effect against Streptococcus mutans and their dental polishing effect
Authors: Saita Kanako , Nagaoka Shoji , Shirosaki Tomohiro , Horikawa Maki , Ihara Hirotaka
Published: February 2020

Nontoxic and biodegradable chitosan is potentially useful in various applications. We prepared submicron chitosan particles with high dispersibility in aqueous solution utilizing the electrostatic interaction phase separation method described in a previous report, but using citric acid as the polyvalent anionic compound instead of sodium sulfate. The submicron chitosan particles showed significant antibacterial activity and anti-adhesive action against Streptococcus mutans, even at around neutral pH. However, chitosan granules showed no antibacterial activity under the same conditions. The addition of the chitosan particles to dental polishing paste provided stainless steel discs (the same hardness as dental enamel) with a smoother surface than polishing paste without additives. In view of their submicron size and antibacterial activity, chitosan particles could potentially be multifunctional components of oral and dental cleaning materials.
Quasi-tomography by free space line field spectral domain optical coherence reflectometry
Authors: Lawman Samuel , Williams Bryan M , Zheng Yalin , Shen Yao-chun
Published: February 2020

This paper reports the development of a new technique, free space line field spectral domain optical coherence reflectometry (LF-SD-OCR), which is able to produce tomographic like (quasi) images. Furthermore, the capabilities and cost benefits of the technique are demonstrated by constructing a handheld LF-SD-OCR device. For glossy paint systems and other suitable samples, the line field format produces quasi-tomographic (cross-sectional) imaging through the layers, with axial and lateral image resolutions of 1.3 µm and 40 µm respectively. From these, the clear coat thicknesses on the bonnet of cars were measured by graph search segmentation and maximum A-scan projection. In comparison with the widely used single point ultrasound and optical devices, our technique gives the user more confident interpretation of the results as it produces a cross-sectional image of the sample in a single-shot fashion without the need of any mechnical scanning. In addition, the produced device has higher resolution and lower cost (£1660 cost of the constructed one-off prototype as compared with over £10K for comparable universally capable ultrasonic devices), making the technique an economically viable alternative to ultrasound in the quality assurance of coating systems and other application areas such as plastic film manufacturing control.
A new route for laser cooling and trapping of cold molecules: Intensity-gradient cooling of MgF molecules using localized hollow beams
Authors: Yan Kang , Wei Bin , Yin Yaling , Xu Supeng , Xu Liang , Xia Meng , Gu Ruoxi , Xia Yong , Yin Jianping
Published: February 2020

We propose a promising scheme to prepare ultracold MgF molecules from a slowed cold molecular beam by using three-dimensional pure intensity-gradient induced Sisyphus cooling. The cooling is based on a blue-detuned localized hollow beam and a weak repumping beam. We investigate the dynamic process in the trap with the method of the Monte-Carlo simulations, verifying the feasibility. Our results show that achieving sub-Doppler temperature should be possible in such a well-designed trap; the trapped MgF molecules with initial temperature of

1

mK

can be directly cooled to the final equilibrium temperature of about

46.5

μ
K
,

well below the Doppler limit (about

527.9

μ
K

for MgF); meanwhile, molecules with initial temperature of

14

mK

can be even cooled to about

68.7

μ
K
.
Fermion dark matter and radiative neutrino masses from spontaneous lepton number breaking
Authors: Bonilla Cesar , Vega Leon M G de la , Lamprea J M , Lineros Roberto A , Peinado Eduardo
Published: February 2020

In this paper, we study the viability of having a fermion Dark Matter particle below the TeV mass scale in connection to the neutrino mass generation mechanism. The simplest realisation is achieved within the scotogenic model where neutrino masses are generated at the 1-loop level. Hence, we consider the case where the dark matter particle is the lightest

Z

2

-odd Majorana fermion running in the neutrino mass loop. We assume that lepton number is broken dynamically due to a lepton number carrier scalar singlet which acquires a non-zero vacuum expectation value. In the present scenario the Dark Matter particles can annihilate via t- and s-channels. The latter arises from the mixing between the new scalar singlet and the Higgs doublet. We identify three different Dark Matter mass regions below 1 TeV that can account for the right amount of dark matter abundance in agreement with current experimental constraints. We compute the Dark Matter-nucleon spin-independent scattering cross-section and find that the model predicts spin-independent cross-sections ‘naturally’ dwelling below the current limit on direct detection searches of Dark Matter particles reported by XENON1T.
Quantum correlations in the Kerr Ising model
Authors: Kewming M J , Shrapnel S , Milburn G J
Published: February 2020

In this article we present a full description of the quantum Kerr Ising model—a linear optical network of parametrically pumped Kerr nonlinearities. We consider the non-dissipative Kerr Ising model and, using variational techniques, show that the energy spectrum is primarily determined by the adjacency matrix in the Ising model and exhibits highly non-classical cat like eigenstates. We then introduce dissipation to give a quantum mechanical treatment of the measurement process based on homodyne detection via the conditional stochastic Schrodinger equation. Finally, we identify a quantum advantage in comparison to the classical analogue for the example of two anti-ferromagnetic cavities.
Evidence of a new class of cnoidal electron holes exhibiting intrinsic substructures, its impact on linear (and nonlinear) Vlasov theories and role in anomalous transport
Authors: Schamel Hans , Mandal Debraj , Sharma Devendra
Published: February 2020

Novel types of solitary electron holes or in more general terms a novel class of cnoidal electron holes propagating in collisionless, driven plasmas is found numerically and described analytically. These structural modes are distinguished by substructures both in the electron density in real space and in the trapped electron distribution function in velocity space and are due to a two-fold trapping scenario; a regular one, called β-trapping, and a weakly singular one, called γ-trapping. Although the latter already appears early in O(ϕ) in the

ϕ

-expansion of the density, where ϕ is the electrostatic potential, it is the regular β-trapping effect, appearing in O(ϕ
3/2), that remains the main cause of these new class of self-consistent structures. Through a proper participation of both trapping mechanisms the shortcomings (inconsistencies) of undamped linear wave theories (Landau, van Kampen) are nonlinearly rectified becoming true solutions of the Vlasov-Poisson system at this kinetic level of plasma description only. They hence provide the right key to the strictly nonlinear, kinetic world of undamped, coherent, small amplitude structures in driven, collisionless plasmas. A cusp-like slope singularity of the otherwise continuous electron distribution f

e
along the contour of a separatrix, on the other hand, exposes thereby a limit for the reliability of a kinetic nonlinear Vlasov-Poisson description and a simulation of structure formation in intermittent turbulent plasmas. It points to a new, deeper settled physics caused by a local enhancement of collisionality near separatrices through the generation of correlations. It is suggested that multiple trapping has the same origin than chaos in the particle trajectories near resonance, namely the non-integrability of discrete particle dynamics.