bluuebunny/crossref_metadata_2025 huggingface dataset:
Sichtbarkeit im Internet steigern – So werden Sie gefunden!
Authors: Gräfe Ann-Kathrin
Published: March 2018

Viele Therapeuten haben mittlerweile eine eigene Praxis-Homepage, um besonders jüngere und internetaffine Patienten zu erreichen. Oft aber ist diese bei einer Google-Suche schlecht zu finden. Wenn Sie die folgenden Punkte beherzigen, können Sie Ihre Sichtbarkeit im Netz erheblich steigern.
Farb-Doppler-Sonografie – Schritt für Schritt
Authors: Bönhof Leoni , Steffgen Ludwig , Bönhof Jörg
Published: March 2018

Step by step explanation for Color-Doppler-Sonography dealing with the transducer-application and the adjustments of the system for an optimal Doppler-angle as well as the adequate setting of scale, gain, color-box and Doppler-center-frequency.
Layer-Cake Figurations and Hide-and-Show Resistance in Cambodia
Authors: Lilja Mona
Published: March 2018

This article adds to previous research, by connecting the concept of resistance to practices of self-making and the embodying of various gendered images. In this article, I advance that women politicians, activists and NGO workers in Cambodia, who seem to repeat and maintain established gender discourses, actually use these discourses and the existence of a multilayered figuration as a ‘hiding place’. This can be understood as various gendered discourses and figurations being utilised as resistance. In order to further explore this pattern, the article introduces the concepts of hide-and-show resistance and layer-cake figurations. The notion of figurations, as situated and culturally differentiated, becomes an important starting point, displaying resistance that originates from the way we are constituted in a local–transnational, material and fast-changing world.
Questions of Presence
Authors: Lewis Gail
Published: March 2018

This article considers some of the ways in which ‘the black woman’ as both representation and embodied, sentient being is rendered visible and invisible, and to link these to the multiple and competing ways in which she is ‘present’. The issues are engaged through three distinct but overlapping conceptualisations of ‘presence’. ‘Presence’ as conceived (and highly contested) in performance studies; ‘presence’ as conceived and worked with in psychoanalysis; and ‘presence’ as decolonising political praxis among Indigenous communities. I use these conceptualisations of presence to consider the various ways in which the black woman as figure and as embodied/sentient subject has been made present/absent in different discursive registers. I also explore what is foreclosed and how this is itself linked to legacies of colonial ‘worlding’. I end with consideration of alternative modes of black women's presence and how this offers a resource for new modes of sociality.
Slovenia's Socialist Superwoman: Feeding the Family, Nourishing the Nation
Authors: Kamin Tanja , Vezovnik Andreja
Published: March 2018

This article explores how the Slovenian women's lifestyle magazine Naša žena ( Our Woman) helped the Yugoslavian socialist project construct and shape the ideal socialist woman, and argues that she became the crucial ally in implementing socialist ideas in the everyday lives of Slovenians. The article shows how texts on food preparation and consumption, as well as those touching on household management and family care, published in Naša žena from 1960 to 1991 played an important part in the ‘civilising’ process that shaped behaviour, directed cultural and social practices, influenced social relations and constructed women's identities during socialism. We show how food-related texts (articles, recipes, columns, advertisements and advertorials) were never far removed from the larger political and economic socialist realities. In fact, they bore witness to changes in living standards and told stories about gender regimes, socialist ideologies and fantasies. These texts belong to a corpus of social transcripts that guide collective understandings of what it means to select, prepare, cook and eat food; what constitutes good cooking and eating; and who is responsible for preparing meals. Despite official socialist feminist rhetoric about freeing women from backward patriarchal arrangements, this article shows that texts offering food-related advice in socialist Yugoslavia contained explicit instructions for the ‘correct’ performance of the social roles of women, legitimising women's roles as worker, mother, wife and housekeeper. Above all, a woman was to be an ‘engineer’ of the private domain whose goals were to feed her family and keep the nation healthy and hence productive, and to modernise her kitchen in support of the technological and economic development of Yugoslavia.
Absolute proton hydration free energy, surface potential of water, and redox potential of the hydrogen electrode from first principles: QM/MM MD free-energy simulations of sodium and potassium hydration
Authors: Hofer Thomas S. , Hünenberger Philippe H.
Published: March 2018

The absolute intrinsic hydration free energy GH+,wat◦ of the proton, the surface electric potential jump χwat◦ upon entering bulk water, and the absolute redox potential VH+,wat◦ of the reference hydrogen electrode are cornerstone quantities for formulating single-ion thermodynamics on absolute scales. They can be easily calculated from each other but remain fundamentally elusive, i.e., they cannot be determined experimentally without invoking some extra-thermodynamic assumption (ETA). The Born model provides a natural framework to formulate such an assumption (Born ETA), as it automatically factors out the contribution of crossing the water surface from the hydration free energy. However, this model describes the short-range solvation inaccurately and relies on the choice of arbitrary ion-size parameters. In the present study, both shortcomings are alleviated by performing first-principle calculations of the hydration free energies of the sodium (Na+) and potassium (K+) ions. The calculations rely on thermodynamic integration based on quantum-mechanical molecular-mechanical (QM/MM) molecular dynamics (MD) simulations involving the ion and 2000 water molecules. The ion and its first hydration shell are described using a correlated ab initio method, namely resolution-of-identity second-order Møller-Plesset perturbation (RIMP2). The next hydration shells are described using the extended simple point charge water model (SPC/E). The hydration free energy is first calculated at the MM level and subsequently increased by a quantization term accounting for the transformation to a QM/MM description. It is also corrected for finite-size, approximate-electrostatics, and potential-summation errors, as well as standard-state definition. These computationally intensive simulations provide accurate first-principle estimates for GH+,wat◦, χwat◦, and VH+,wat◦, reported with statistical errors based on a confidence interval of 99%. The values obtained from the independent Na+ and K+ simulations are in excellent agreement. In particular, the difference between the two hydration free energies, which is not an elusive quantity, is 73.9 ± 5.4 kJ mol−1 (K+ minus Na+), to be compared with the experimental value of 71.7 ± 2.8 kJ mol−1. The calculated values of GH+,wat◦, χwat◦, and VH+,wat◦ (−1096.7 ± 6.1 kJ mol−1, 0.10 ± 0.10 V, and 4.32 ± 0.06 V, respectively, averaging over the two ions) are also in remarkable agreement with the values recommended by Reif and Hünenberger based on a thorough analysis of the experimental literature (−1100 ± 5 kJ mol−1, 0.13 ± 0.10 V, and 4.28 ± 0.13 V, respectively). The QM/MM MD simulations are also shown to provide an accurate description of the hydration structure, dynamics, and energetics.
An efficient zero-order description of the fine structure in the infrared reflection band of cubic ionic crystals and the phonon-polariton dispersion using Lorentz gauge
Authors: Meskers Stefan C. J.
Published: March 2018

The reflection of infrared light by ionic crystals with cubic symmetry such as lithium fluoride, LiF, is analyzed in terms of phonon-polaritons. In contrast to the conventional view on phonon-polaritons that uses the Coulomb gauge and assumes a purely local dielectric response of the material, we here develop an alternative description making use of the Lorentz gauge. This involves retarded interactions between charges, implying a non-local response of the material to electromagnetic radiation. The resulting new phonon-polariton dispersion relation features polaritons with negative group velocity in the frequency range in between the transverse (ωT) and longitudinal frequency (ωL). By contrast, the conventional description predicts, in zero order, the absence of any propagating polaritons in the frequency interval between ωT and ωL. The new dispersion relation provides an efficient, zero-order description of the fine structure within the reststrahlen band of LiF. The local minimum near the middle of the reflectance band is due to excitation of a phonon-polariton whose energy and momentum matches that of the incoming photon. The Lorentz gauge description can also describe off-normal reflection and accounts for the experimentally observed widening of the reflection band with increasing angle of incidence.
Strategy to overcome recombination limited photocurrent generation in CsPbX3 nanocrystal arrays
Authors: Mir Wasim J. , Livache Clément , Goubet Nicolas , Martinez Bertille , Jagtap Amardeep , Chu Audrey , Coutard Nathan , Cruguel Hervé , Barisien Thierry , Ithurria Sandrine , Nag Angshuman , Dubertret Benoit , Ouerghi Abdelkarim , Silly Mathieu G. , Lhuillier Emmanuel
Published: March 2018

We discuss the transport properties of CsPbBrxI3−x perovskite nanocrystal arrays as a model ensemble system of caesium lead halide-based perovskite nanocrystal arrays. While this material is very promising for the design of light emitting diodes, laser, and solar cells, very little work has been devoted to the basic understanding of their (photo)conductive properties in an ensemble system. By combining DC and time-resolved photocurrent measurements, we demonstrate fast photodetection with time response below 2 ns. The photocurrent generation in perovskite nanocrystal-based arrays is limited by fast bimolecular recombination of the material, which limits the lifetime of the photogenerated electron-hole pairs. We propose to use nanotrench electrodes as a strategy to ensure that the device size fits within the obtained diffusion length of the material in order to boost the transport efficiency and thus observe an enhancement of the photoresponse by a factor of 1000.
Symmetry blockade and its breakdown in energy equipartition of square graphene resonators
Authors: Wang Yisen , Zhu Zhigang , Zhang Yong , Huang Liang
Published: March 2018

The interaction between flexural modes due to nonlinear potentials is critical to heat conductivity and mechanical vibration of two dimensional materials such as graphene. Much effort has been devoted to understanding the underlying mechanism. In this paper, we examine solely the out-of-plane flexural modes and identify their energy flow pathway during the equipartition process. In particular, the modes are grouped into four classes by their distinct symmetries. The couplings are significantly larger within a class than between classes, forming symmetry blockades. As a result, the energy first flows to the modes in the same symmetry class. Breakdown of the symmetry blockade, i.e., inter-class energy flow, starts when the displacement profile becomes complex and the inter-class couplings bear nonneglectable values. The equipartition time follows the stretched exponential law and survives in the thermodynamic limit. These results bring fundamental understandings to the Fermi-Pasta-Ulam problem in two dimensional systems with complex potentials and reveal clearly the physical picture of dynamical interactions between the flexural modes, which will be crucial to the understanding of their contribution in high thermal conductivity and mechanism of energy dissipation that may intrinsically limit the quality factor of the resonator.
A review of low density porous materials used in laser plasma experiments
Authors: Nagai Keiji , Musgrave Christopher S. A. , Nazarov Wigen
Published: March 2018

This review describes and categorizes the synthesis and properties of low density porous materials, which are commonly referred to as foams and are utilized for laser plasma experiments. By focusing a high-power laser on a small target composed of these materials, high energy and density states can be produced. In the past decade or so, various new target fabrication techniques have been developed by many laboratories that use high energy lasers and consequently, many publications and reviews followed these developments. However, the emphasis so far has been on targets that did not utilize low density porous materials. This review therefore, attempts to redress this balance and endeavors to review low density materials used in laser plasma experiments in recent years. The emphasis of this review will be on aspects of low density materials that are of relevance to high energy laser plasma experiments. Aspects of low density materials such as densities, elemental compositions, macroscopic structures, nanostructures, and characterization of these materials will be covered. Also, there will be a brief mention of how these aspects affect the results in laser plasma experiments and the constrictions that these requirements put on the fabrication of low density materials relevant to this field. This review is written from the chemists' point of view to aid physicists and the new comers to this field.
Vanishing mean volume velocity in isothermal isobaric diffusion of a binary fluid mixture
Authors: Felderhof B. U.
Published: March 2018

It is shown that in isothermal isobaric diffusion of a binary fluid mixture, the mean volume velocity vanishes in the linear regime, independent of the equation of state. The partial specific volumes of the two components are uniform and constant in the process of mutual diffusion. The properties lead to a simple derivation of the de Groot-Mazur thermodynamic factor in the diffusion coefficient. The properties also imply that the diffusive volume flux defined by Brenner is proportional to the mass current density, and is therefore not a quantity of independent interest.
A simple mass-conserved level set method for simulation of multiphase flows
Authors: Yuan H.-Z. , Shu C. , Wang Y. , Shu S.
Published: March 2018

In this paper, a modified level set method is proposed for simulation of multiphase flows with large density ratio and high Reynolds number. The present method simply introduces a source or sink term into the level set equation to compensate the mass loss or offset the mass increase. The source or sink term is derived analytically by applying the mass conservation principle with the level set equation and the continuity equation of flow field. Since only a source term is introduced, the application of the present method is as simple as the original level set method, but it can guarantee the overall mass conservation. To validate the present method, the vortex flow problem is first considered. The simulation results are compared with those from the original level set method, which demonstrates that the modified level set method has the capability of accurately capturing the interface and keeping the mass conservation. Then, the proposed method is further validated by simulating the Laplace law, the merging of two bubbles, a bubble rising with high density ratio, and Rayleigh-Taylor instability with high Reynolds number. Numerical results show that the mass is a well-conserved by the present method.
Stability of relativistic quantum electrodynamics in the Coulomb gauge
Authors: Jäkel Christian D. , Wreszinski Walter F.
Published: March 2018

We show that relativistic quantum electrodynamics in the Coulomb gauge satisfies the following bound, which establishes stability: let H(Λ, V) denote the Hamiltonian of QED1+3 on the three-dimensional torus of volume V and with ultraviolet cutoff Λ. Then there exists a constant 0 < μ(Λ, V) < ∞ (the vacuum energy renormalization) such that the renormalized Hamiltonian is positive: Hren(Λ,V)≡ HΛ,V+μΛ,V⋅1≥ 0.
Gaussian approximation potential modeling of lithium intercalation in carbon nanostructures
Authors: Fujikake So , Deringer Volker L. , Lee Tae Hoon , Krynski Marcin , Elliott Stephen R. , Csányi Gábor
Published: March 2018

We demonstrate how machine-learning based interatomic potentials can be used to model guest atoms in host structures. Specifically, we generate Gaussian approximation potential (GAP) models for the interaction of lithium atoms with graphene, graphite, and disordered carbon nanostructures, based on reference density functional theory data. Rather than treating the full Li–C system, we demonstrate how the energy and force differences arising from Li intercalation can be modeled and then added to a (prexisting and unmodified) GAP model of pure elemental carbon. Furthermore, we show the benefit of using an explicit pair potential fit to capture “effective” Li–Li interactions and to improve the performance of the GAP model. This provides proof-of-concept for modeling guest atoms in host frameworks with machine-learning based potentials and in the longer run is promising for carrying out detailed atomistic studies of battery materials.
Comparative performance of different energy storage devices in AGC of multi-source system including geothermal power plant
Authors: Tasnin Washima , Saikia Lalit Chandra
Published: March 2018

This paper highlights an attempt of comparing the performance of several energy storage (ES) devices such as battery ES, flywheel ES, capacitive ES, superconducting magnetic ES, ultra-capacitors, and redox flow batteries (RFBs) in automatic generation control of an interconnected system. The considered system comprises conventional thermal, hydro, wind, and solar photovoltaic generations wherein a geothermal power plant (GTPP) is also incorporated. The thermal and hydro systems are provided with appropriate generation rate constraints. A new fractional order (FO) cascade controller named as the FO proportional-integral–FO proportional-integral-derivative (FOPI-FOPID) is proposed as a secondary controller, and its performance is compared with the commonly used classical controllers. A powerful stochastic algorithm called the Sine Cosine Algorithm has been used to optimize the controller gains and other parameters. Analyses of the dynamic responses reveal the superiority of FOPI-FOPID over the others in terms of settling time, peak deviation, and magnitude of oscillation. The effect due to introduction of GTPP has been examined, and the responses disclose that integration of GTPP leads to better dynamics. The comparison of performances of various ES devices in the presence of the FOPI-FOPID controller highlights the predominance of RFB over others.
Does an electronic continuum correction improve effective short-range ion-ion interactions in aqueous solution?
Authors: Bruce Ellen E. , van der Vegt Nico F. A.
Published: March 2018

Non-polarizable force fields for hydrated ions not always accurately describe short-range ion-ion interactions, frequently leading to artificial ion clustering in bulk aqueous solutions. This can be avoided by adjusting the nonbonded anion-cation or cation-water Lennard-Jones parameters. This approach has been successfully applied to different systems, but the parameterization is demanding owing to the necessity of separate investigations of each ion pair. Alternatively, polarization effects may effectively be accounted for using the electronic continuum correction (ECC) of Leontyev et al. [J. Chem. Phys. 119, 8024 (2003)], which involves scaling the ionic charges with the inverse square-root of the water high-frequency dielectric permittivity. ECC has proven to perform well for monovalent salts as well as for divalent salts in water. Its performance, however, for multivalent salts with higher valency remains unexplored. The present work illustrates the applicability of the ECC model to trivalent K3PO4 and divalent K2HPO4 in water. We demonstrate that the ECC models, without additional tuning of force field parameters, provide an accurate description of water-mediated interactions between salt ions. This results in predictions of the osmotic coefficients of aqueous K3PO4 and K2HPO4 solutions in good agreement with experimental data. Analysis of ion pairing thermodynamics in terms of contact ion pair (CIP), solvent-separated ion pair, and double solvent-separated ion pair contributions shows that potassium-phosphate CIP formation is stronger with trivalent than with divalent phosphate ions.
Differences in 1D electron plasma wake field acceleration in MeV versus GeV and linear versus blowout regimes
Authors: Tsiklauri David
Published: March 2018

In some laboratory and most astrophysical situations, plasma wake-field acceleration of electrons is one dimensional, i.e., variation transverse to the beam's motion can be ignored. Thus, one dimensional, particle-in-cell (PIC), fully electromagnetic simulations of electron plasma wake field acceleration are conducted in order to study the differences in electron plasma wake field acceleration in MeV versus GeV and linear versus blowout regimes. First, we show that caution needs to be taken when using fluid simulations, as PIC simulations prove that an approximation for an electron bunch not to evolve in time for a few hundred plasma periods only applies when it is sufficiently relativistic. This conclusion is true irrespective of the plasma temperature. We find that in the linear regime and GeV energies, the accelerating electric field generated by the plasma wake is similar to the linear and MeV regimes. However, because GeV energy driving bunch stays intact for a much longer time, the final acceleration energies are much larger in the GeV energies case. In the GeV energy range and blowout regime, the wake's accelerating electric field is much larger in amplitude compared with the linear case and also plasma wake geometrical size is much larger. Thus, the correct positioning of the trailing bunch is needed to achieve the efficient acceleration. For the considered case, optimally, there should be approximately (90–100)c/ωpe distance between the trailing and driving electron bunches in the GeV blowout regime.
Supercavitating flow around high-speed underwater projectile near free surface induced by air entrainment
Authors: Xu Chang , Huang Jian , Wang Yiwei , Wu Xiaocui , Huang Chenguang , Wu Xianqian
Published: March 2018

Cavitating flow near free surface is a complicated issue and may provide new inspiration on high-speed surface cruising. This study observes stable supercavitating flow as a new phenomenon in a launch experiment of axisymmetric projectile when the upper side of the projectile coincides with the free surface. A numerical approach is established using large eddy-simulation and volume-of-fluid methods, and good agreements are achieved between numerical and experimental results. Supercavity formation mechanism is revealed by analyzing the experiment photographs and the iso-surface of 90% water volume fraction in numerical results. The entrainment of a large amount of air into the cavity can cause the pressure inside the cavity to similarly increase with the pressure outside the cavity, which makes the actual cavitation number close to zero and is similar to supercavitation. Cases with various headforms of the projectile and cavitation numbers on the cavitating flow, as well as the drag reduction effects are further examined. Results indicate that the present strategy near the free surface could possibly be a new effective approach for high-speed cruising after vigorous design optimization in the future.
Curvature dependence of the effect of ionic functionalization on the attraction among nanoparticles in dispersion
Authors: Jabes B. Shadrack , Bratko Dusan , Luzar Alenka
Published: March 2018

Solubilization of nanoparticles facilitates nanomaterial processing and enables new applications. An effective method to improve dispersibility in water is provided by ionic functionalization. We explore how the necessary extent of functionalization depends on the particle geometry. Using molecular dynamics/umbrella sampling simulations, we determine the effect of the solute curvature on solvent-averaged interactions among ionizing graphitic nanoparticles in aqueous dispersion. We tune the hydrophilicity of molecular-brush coated fullerenes, carbon nanotubes, and graphane platelets by gradually replacing a fraction of the methyl end groups of the alkyl coating by the ionizing –COOK or –NH3Cl groups. To assess the change in nanoparticles’ dispersibility in water, we determine the potential-of-mean-force profiles at varied degrees of ionization. When the coating comprises only propyl groups, the attraction between the hydrophobic particles intensifies from spherical to cylindrical to planar geometry. This is explained by the increasing fraction of surface groups that can be brought into contact and the reduced access to water molecules, both following the above sequence. When ionic groups are added, however, the dispersibility increases in the opposite order, with the biggest effect in the planar geometry and the smallest in the spherical geometry. These results highlight the important role of geometry in nanoparticle solubilization by ionic functionalities, with about twice higher threshold surface charge necessary to stabilize a dispersion of spherical than planar particles. At 25%–50% ionization, the potential of mean force reaches a plateau because of the counterion condensation and saturated brush hydration. Moreover, the increase in the fraction of ionic groups can weaken the repulsion through counterion correlations between adjacent nanoparticles. High degrees of ionization and concomitant ionic screening gradually reduce the differences among surface interactions in distinct geometries until an essentially curvature-independent dispersion environment is created. Insights into tuning nanoparticle interactions can guide the synthesis of a broad class of nonpolar nanoparticles, where solubility is achieved by ionic functionalization.
Constructing first-principles phase diagrams of amorphous LixSi using machine-learning-assisted sampling with an evolutionary algorithm
Authors: Artrith Nongnuch , Urban Alexander , Ceder Gerbrand
Published: March 2018

The atomistic modeling of amorphous materials requires structure sizes and sampling statistics that are challenging to achieve with first-principles methods. Here, we propose a methodology to speed up the sampling of amorphous and disordered materials using a combination of a genetic algorithm and a specialized machine-learning potential based on artificial neural networks (ANNs). We show for the example of the amorphous LiSi alloy that around 1000 first-principles calculations are sufficient for the ANN-potential assisted sampling of low-energy atomic configurations in the entire amorphous LixSi phase space. The obtained phase diagram is validated by comparison with the results from an extensive sampling of LixSi configurations using molecular dynamics simulations and a general ANN potential trained to ∼45 000 first-principles calculations. This demonstrates the utility of the approach for the first-principles modeling of amorphous materials.
The coexistence temperature of hydrogen clathrates: A molecular dynamics study
Authors: Luis D. P. , Romero-Ramirez I. E. , González-Calderón A. , López-Lemus J.
Published: March 2018

Extensive molecular dynamics simulations in the equilibrium isobaric-isothermal (NPT) ensemble were developed to determine the coexistence temperatures of the water hydrogen mixture using the direct coexistence method. The water molecules were modeled using the four-site TIP4P/Ice analytical potential, and the hydrogen molecules were described using a three-site potential. The simulations were performed at different pressures (p = 900, 1500, 3000, and 4000 bars). At each pressure, a series of simulations were developed at different temperatures (from 230 to 270 K). Our results followed a line parallel to the experimental coexistence temperatures and underestimated these temperatures by approximately 25 K in the investigated range. The final configurations could or could not contain a fluid phase depending on the pressure, in accordance with the phase diagram. In addition, we explored the dynamics of the H2 molecules through clathrate hydrate cages and observed different behaviors of the H2 molecules in the small cages and the large cages of the sII structure.
Characteristics of OMVPE grown GaAsBi QW lasers and impact of post-growth thermal annealing
Authors: Kim Honghyuk , Guan Yingxin , Babcock Susan E. , Kuech Thomas F. , Mawst Luke J.
Published: March 2018

Laser diodes employing a strain-compensated GaAs1−xBix/GaAs1−yPy single quantum well (SQW) active region were grown by organometallic vapor phase epitaxy (OMVPE). High resolution x-ray diffraction, room temperature photoluminescence, and real-time optical reflectance measurements during the OMVPE growth were used to find the optimum process window for the growth of the active region material. Systematic post-growth in situ thermal anneals of various lengths were carried out in order to investigate the impacts of thermal annealing on the laser device performance characteristics. While the lowest threshold current density was achieved after the thermal annealing for 30 min at 630 °C, a gradual decrease in the external differential quantum efficiency was observed as the annealing time increases. It was observed that the temperature sensitivities of the threshold current density increase while those of lasing wavelength and slope efficiency remain nearly constant with increasing annealing time. Z-contrast scanning transmission electron microscopic) analysis revealed inhomogeneous Bi distribution within the QW active region.
Molecular-dynamics study of propane-hydrate dissociation: Fluctuation-dissipation and non-equilibrium analysis
Authors: Ghaani Mohammad Reza , English Niall J.
Published: March 2018

Equilibrium and non-equilibrium molecular-dynamics (MD) simulations have been performed to investigate thermal-driven break-up of planar propane-hydrate interfaces in contact with liquid water over the 260-320 K range. Two types of hydrate-surface water-lattice molecular termination were adopted, at the hydrate edge with water, for comparison: a 001-direct surface cleavage and one with completed cages. Statistically significant differences in melting temperatures and initial break-up rates were observed between both interface types. Dissociation rates were observed to be strongly dependent on temperature, with higher rates at larger over-temperatures vis-à-vis melting. A simple coupled mass and heat transfer model, developed previously, was applied to fit the observed dissociation profiles, and this helps us to identify clearly two distinct hydrate-decomposition régimes; following a highly temperature-dependent break-up phase, a second well-defined stage is essentially independent of temperature, in which the remaining nanoscale, de facto two-dimensional system’s lattice framework is intrinsically unstable. Further equilibrium MD-analysis of the two-phase systems at their melting point, with consideration of the relaxation times gleaned from the auto-correlation functions of fluctuations in a number of enclathrated guest molecules, led to statistically significant differences between the two surface-termination cases; a consistent correlation emerged in both cases between the underlying, non-equilibrium, thermal-driven dissociation rates sampled directly from melting with that from an equilibrium-MD fluctuation-dissipation approach.
Effective charges and zeta potentials of oil in water microemulsions in the presence of Hofmeister salts
Authors: dos Santos Alexandre P. , Levin Yan
Published: March 2018

We present a theory which allows us to calculate the effective charge and zeta potential of oil droplets in microemulsions containing Hofmeister salts. A modified Poisson-Boltzmann equation is used to account for the surface and ion polarizations and hydrophobic and dispersion interactions. The ions are classified as kosmotropes and chaotropes according to their Jones-Dole viscosity B coefficient. Kosmotropes stay hydrated and do not enter into the oil phase, while chaotropes can adsorb to the oil-water interface. The effective interaction potentials between ions and oil-water interface are parametrized so as to accurately account for the excess interfacial tension.
Structural, magnetic, and electrical properties of perpendicularly magnetized Mn4–xFexGe thin films
Authors: Niesen Alessia , Teichert Niclas , Matalla-Wagner Tristan , Balluf Jan , Dohmeier Niklas , Glas Manuel , Klewe Christoph , Arenholz Elke , Schmalhorst Jan-Michael , Reiss Günter
Published: March 2018

We investigated the structural, magnetic, and electrical properties of the perpendicularly magnetized Mn4-xFexGe thin films (0.3 ≤ x ≤ 1). The tetragonally distorted structure was verified for all investigated stoichiometries. High coercive fields in the range of 1.61 T to 3.64 T at room temperature were measured and showed increasing behavior with decreasing Fe content. The magnetic moments range from (0.16 ± 0.02) μB/f.u for Mn3Fe1Ge to (0.08 ± 0.01) μB/f.u for Mn3.4Fe0.6Ge. X-ray absorption spectroscopy revealed ferromagnetic coupling of the Mn and Fe atoms in Mn4-xFexGe and the ferrimagnetic ordering of the Mn magnetic moments. Anomalous Hall effect measurements showed sharp magnetization switching. The resistivity values are in the range of 207 μΩ cm to 457 μΩ cm depending on the stoichiometry. From the contribution of the ordinary Hall effect in the anomalous Hall effect measurements, Hall constants, the charge carrier density, and mobility were deduced. The thermal conductivity was calculated using the Wiedemann-Franz law. All these values are strongly influenced by the stoichiometry. An alternative method was introduced for the determination of perpendicular magnetic anisotropy. The values range between 0.26 MJ/m3 and 0.36 MJ/m3.
Biorthogonal vectors, sesquilinear forms, and some physical operators
Authors: Bagarello F. , Inoue H. , Trapani C.
Published: March 2018

Continuing the analysis undertaken in previous articles, we discuss some features of non-self-adjoint operators and sesquilinear forms which are defined starting from two biorthogonal families of vectors, like the so-called generalized Riesz systems, enjoying certain properties. In particular, we discuss what happens when they forms two D-quasi-bases.
Quantifying fluorescence enhancement for slowly diffusing single molecules in plasmonic near fields
Authors: Caldarola Martín , Pradhan Biswajit , Orrit Michel
Published: March 2018

Gold nanorods are extensively used for single-molecule fluorescence enhancement as they are easy to synthesize, bio-compatible, and provide high light confinement at their nanometer-sized tips. The current way to estimate fluorescence enhancement relies on binned time traces or on fluorescence correlation spectroscopy. We report on novel ways to extract the enhancement factor in a single-molecule enhancement experiment, avoiding the arbitrary selection of one or a few high-intensity burst(s). These new estimates for the enhancement factor make use of the whole distribution of intensity bursts or of the interphoton delay distribution, which avoids the arbitrary binning of the fluorescence intensity time traces. We present experimental results on the bi-dimensional case, experimentally achieved using a lipid bilayer to support the diffusion of fluorophores. We support our findings with histograms of fluorescence bursts and with an analytical derivation of the interphoton delay distribution of (nearly) immobilized emitters from the fluorescence intensity profile.
Improved local lattice Monte Carlo simulation for charged systems
Authors: Jiang Jian , Wang Zhen-Gang
Published: March 2018

Maggs and Rossetto [Phys. Rev. Lett. 88, 196402 (2002)] proposed a local lattice Monte Carlo algorithm for simulating charged systems based on Gauss’s law, which scales with the particle number N as O(N). This method includes two degrees of freedom: the configuration of the mobile charged particles and the electric field. In this work, we consider two important issues in the implementation of the method, the acceptance rate of configurational change (particle move) and the ergodicity in the phase space sampled by the electric field. We propose a simple method to improve the acceptance rate of particle moves based on the superposition principle for electric field. Furthermore, we introduce an additional updating step for the field, named “open-circuit update,” to ensure that the system is fully ergodic under periodic boundary conditions. We apply this improved local Monte Carlo simulation to an electrolyte solution confined between two low dielectric plates. The results show excellent agreement with previous theoretical work.
Double photoionization of propylene oxide: A coincidence study of the ejection of a pair of valence-shell electrons
Authors: Falcinelli Stefano , Vecchiocattivi Franco , Alagia Michele , Schio Luca , Richter Robert , Stranges Stefano , Catone Daniele , Arruda Manuela S. , Mendes Luiz A. V. , Palazzetti Federico , Aquilanti Vincenzo , Pirani Fernando
Published: March 2018

Propylene oxide, a favorite target of experimental and theoretical studies of circular dichroism, was recently discovered in interstellar space, further amplifying the attention to its role in the current debate on protobiological homochirality. In the present work, a photoelectron-photoion-photoion coincidence technique, using an ion-imaging detector and tunable synchrotron radiation in the 18.0–37.0 eV energy range, permits us (i) to observe six double ionization fragmentation channels, their relative yields being accounted for about two-thirds by the couple (C2H4+, CH2O+) and one-fifth by (C2H3+, CH3O+); (ii) to measure thresholds for their openings as a function of photon energy; and (iii) to unravel a pronounced bimodality for a kinetic-energy-released distribution, fingerprint of competitive non-adiabatic mechanisms.
Influence factors and temperature reliability of ohmic contact on AlGaN/GaN HEMTs
Authors: Song Liang , Fu Kai , Zhao Jie , Yu Guohao , Hao Ronghui , Zhang Xiaodong , Chen Fu , Fan Yaming , Cai Yong , Zhang Baoshun
Published: March 2018

In this paper, we have studied the performance of Ti/Al/Ni/Au ohmic contact with different Al and Au thicknesses and pretreatments. The temperature dependence of contact resistances (Rc) was investigated and it shows that there are different optimal annealing temperatures with different metal thicknesses and pretreatments. The optimal annealing temperature is affected by Al and Au thickness and AlGaN thickness. The etched AlGaN barrier is useful to achieve good ohmic contact (0.24 Ω·mm) with a low annealing temperature. Only the contact resistances of the samples with 130 nm Al layer kept stable and the contact resistances of the samples with 100nm and 160 nm Al layers increased with the measurement temperatures. The contact resistances showed a similar increase and then keep stable trend for all the samples in the long-term 400 °C aging process. The ohmic metal of 20/130/50/50 nm Ti/Al/Ni/Au with ICP etching is the superior candidate considering the contact resistance and reliability.
Classification of digital affine noncommutative geometries
Authors: Majid Shahn , Pachoł Anna
Published: March 2018

It is known that connected translation invariant n-dimensional noncommutative differentials dxi on the algebra k[x1, …, xn] of polynomials in n-variables over a field k are classified by commutative algebras V on the vector space spanned by the coordinates. These data also apply to construct differentials on the Heisenberg algebra “spacetime” with relations [xμ, xν] = λΘμν, where Θ is an antisymmetric matrix, as well as to Lie algebras with pre-Lie algebra structures. We specialise the general theory to the field k=F2 of two elements, in which case translation invariant metrics (i.e., with constant coefficients) are equivalent to making V a Frobenius algebra. We classify all of these and their quantum Levi-Civita bimodule connections for n = 2, 3, with partial results for n = 4. For n = 2, we find 3 inequivalent differential structures admitting 1, 2, and 3 invariant metrics, respectively. For n = 3, we find 6 differential structures admitting 0, 1, 2, 3, 4, 7 invariant metrics, respectively. We give some examples for n = 4 and general n. Surprisingly, not all our geometries for n ≥ 2 have zero quantum Riemann curvature. Quantum gravity is normally seen as a weighted “sum” over all possible metrics but our results are a step towards a deeper approach in which we must also “sum” over differential structures. Over F2 we construct some of our algebras and associated structures by digital gates, opening up the possibility of “digital geometry.”
Local well-posedness for a compressible non-isothermal model for nematic liquid crystals
Authors: Fan Jishan , Li Fucai , Nakamura Gen
Published: March 2018

In this paper, we prove the local well-posedness of strong solutions to a compressible non-isothermal model for nematic liquid crystals in a bounded domain Ω⊂R3 provided that the initial data satisfy a natural compatibility condition. The assumption on the positivity of initial density is not needed here, and it may vanish in an open subset of Ω.
Ignorance is a bliss: Mathematical structure of many-box models
Authors: Tylec Tomasz I. , Kuś Marek
Published: March 2018

We show that the propositional system of a many-box model is always a set-representable effect algebra. In particular cases of 2-box and 1-box models, it is an orthomodular poset and an orthomodular lattice, respectively. We discuss the relation of the obtained results with the so-called Local Orthogonality principle. We argue that non-classical properties of box models are the result of a dual enrichment of the set of states caused by the impoverishment of the set of propositions. On the other hand, quantum mechanical models always have more propositions as well as more states than the classical ones. Consequently, we show that the box models cannot be considered as generalizations of quantum mechanical models and seeking additional principles that could allow us to “recover quantum correlations” in box models are, at least from the fundamental point of view, pointless.
Effect of glycerin supplementation on the expression of antioxidant and mitochondrial genes in broilers
Authors: Araújo R. S. , Sousa K. R. S. , Sousa F. C. B. , Oliveira A. C. , Dourado L. R. B. , Guimarães S. E. F. , Silva W. , Biagiotti D. , Bayão G. F. V. , Araujo A. C.
Published: March 2018

Crude glycerin has been used as an alternative energy source in animal feeding and can thus change both the animal’s performance and the levels of gene expression related to energy production process and the antioxidant system, since the effect of glycerin depends on its degree of purity in the diet. The aim of this study was to evaluate the effect of crude glycerin inclusion (0, 6 and 12%) in the diet has on performance characteristics and mRNA abundance of genes associated with the mitochondrial function (uncoupling protein (UCP), cytochrome C oxidase subunit III (COX III) and adenine nucleotide transporter (ANT)) and those that combat the reactive oxygen species (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) in the liver and muscle of broilers at 42 days of age. Total RNA was extracted from the tissues, and cDNA was amplified using specific primers for the genes under study through real-time reverse transcription polymerase chain reaction; the endogenous gene used was β-actin. There was no difference between glycerin concentrations for weight gain, feed intake or feed conversion. Greater expression of UCP at muscle and higher GPx expression at liver were observed in broilers fed 12% glycerin. In conclusion, the addition of 12% glycerin to broiler diets increased the expression of UCP and GPx, but did not change broiler performance. Therefore, glycerin can be used as an alternative ingredient without losses.
Nutritional vulnerability in zoeal stages of the yellowline arrow crab Stenorhynchus seticornis (Brachyura: Majoidea)
Authors: Barros-Alves Samara P. , Alves Douglas F. R. , Antunes Mariana , López Greco Laura S. , Negreiros-Fransozo Maria Lucia
Published: March 2018

Knowledge of the critical points in larval stages is essential to evaluate the physiological state of the larvae in their natural environment. This study investigated the nutritional vulnerability index (NVI) of the first (ZI) and second (ZII) zoeal stages of Stenorhynchus seticornis. Zoeae were assigned to two experiments: (1) point of no return (PNR), consisting of treatments with increasing days of starvation and subsequent days of feeding; and (2) point of reserve saturation (PRS), consisting of treatments with increasing days of feeding and subsequent days of starvation. There were two control groups: continuous starvation (CS) and continuous feeding (CF). Mortality was used to estimate the time when 50% of initially starved larvae (PNR50) lost the ability to moult to the next stage and when 50% of initially fed larvae (PRS50) were capable of moulting to the next stage. The mean (±s.d.) development time of ZI and ZII under CF was 4.4±1.2 and 5.1±1.8 days respectively. Mortality in the CF groups was 30 and 52% for ZI and ZII respectively. For ZI, PNR50 and PRS50 were 1.0±0.0 and 2.1±1.0 days respectively. The estimated NVI for ZI was 2.2, which indicates that S. seticornis depends on exogenous food and is considered planktotrophic during the first larval stage.
Expression of kisspeptin protein in hypothalamus and LH profile of growing female lambs
Authors: Polkowska Jolanta , Wójcik-Gładysz Anna , Chmielewska Natalia , Wańkowska Marta
Published: March 2018

Kisspeptin (kp) is considered to be one of the major regulators of the induction of pubertal events via the activation of the gonadotrophin-releasing hormone–LH system. The aim of the present study was to analyse expression of immunoreactive (ir) kp in the hypothalamic neurons of female lambs from the neonatal to the peripubertal period (5 days to 32 weeks) in relation to the plasma LH pattern using immunohistochemistry and image analysis. Hypothalami were collected from female lambs (n = 33) from the infantile, juvenile, prepubertal and peripubertal periods. The population of kp-ir perikarya was detected mainly in the arcuate nucleus and their number increased gradually from 5 to 16 weeks of age and was maintained at a high level up to the peripubertal stage. This was reflected by the significant (P < 0.05) gradual increase in the percentage of hypothalamic area occupied by kp-ir neurons and increase in the number of kp-ir perikarya within the arcuate nucleus. The same pattern of kp immunoreactivity was observed in the median eminence. Plasma LH concentration increased from Week 5 to Weeks 12–16 and further increased at Week 32. LH pulse frequency increased from Week 5 to 32 (P < 0.05). Thus, changes in kp expression reflected changes in the LH pattern during lamb growth. The data obtained provide evidence about the participation of kp in the mechanisms of ontogenic development of ovine reproductive processes.