bluuebunny/crossref_metadata_2025 huggingface dataset:
DIFFUSE XANTHOGRANULOMATOUS PYELONEPHRITIS OCCURRING IN A NON-FUNCTIONAL KIDNEY - A REPORT OF TWO CASES
Authors: Permi Harish S. , P. Rajeev T. , Ravinder Prajwal , N. Sajitha , Hegde Panna
Published: March 2020

Xanthogranulomatous pyelonephritis is a rare debilitating illness resulting in focal or diffuse renal destruction. It is characterized pathologically by lipid-laden foamy macrophages which share many characteristics with true renal neoplasm in terms of its radiographic appearance and ability to involve adjacent structures or organs. It affects non-functioning kidney and is often associated with urinary tract obstruction, infection, nephrolithiasis, diabetes, and immunocompromised state. The treatment is almost universally extirpative and can pose a formidable challenge to the surgeon. We report two cases of diffuse Xanthogranulomatous pyelonephritis occurring in a non-functioning kidney of 38 year old diabetic male and 51 year old male with renal calculus.
SCROTAL CALCINOSIS - RARE CASE REPORTS OF TWO CASES
Authors: Permi Harish S. , Shetty Rohan , Alva Shalmali , Shetty Balakrishna , Ballal Rajesh , K. Jayaprakash Shetty
Published: March 2020

Scrotal calcinosis is a benign disease characterized by multiple calcified scrotal nodules. The nodules develop slowly over many years and patients usually do not seek for treatment, until they grow to large size. Histopathological examination shows deposition of basophilic amorphous material surrounded by giant cell granulomatous reaction. We report two cases of scrotal calcinosis occurring in 27 year and 45 year old males who presented with multiple scrotal swellings. Clinical diagnosis was multiple sebaceous cysts. On histopathology, excised swellings showed deposition of calcium with giant cell reaction. On regular follow up both are doing fine without any recurrence.
PROVISIONAL RESTORATIONS IN PROSTHODONTIC REHABILITATIONS - CONCEPTS, MATERIALS AND TECHNIQUES
Authors: D. Krishna Prasad , Shetty Manoj , Alva Harshitha , D. Anupama Prasad
Published: March 2020

Provisional restorations in fixed prosthodontic rehabilitation are important treatment procedures, particularly if the restorations are expected to function for extended periods of time or when additional therapy is required before completion of the rehabilitation. These materials should not only satisfy the mechanical requirements such as strength and resistance to wear but also meet the biologic and esthetic demands. The prognosis of a fixed restoration greatly depends on this interim restoration. This article describes the various materials used for these provisionals and also the techniques used to fabricate them along with their advantages and disadvantages.
Annealing-enhanced birefringence and aggregation in MEH-PPV: A spectroscopic ellipsometry study
Authors: Gaudin Olivier P. M. , Samuel Ifor D. W. , Amriou Samia , Burn Paul L.
Published: March 2020

We have used absorption, photoluminescence (PL), and variable angle spectroscopic ellipsometry (VASE) measurements to investigate the structural changes that take place upon high temperature annealing in spin-coated films of the prototypical conjugated polymer (CP) poly[2-(2′-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEH-PPV). Absorption and VASE measurements reveal that the birefringence of the films increases by approximately a factor of two upon heating, which indicates a significant increase in the alignment of the conjugated polymer (CP) strands within the film plane. Absorption and PL spectra indicate the formation in annealed films of interchain species having lower energy transitions. But these measurements alone do not reveal the type of interchain species formed, such as excimers or aggregates. VASE measurements were used to investigate this feature and clearly reveal a new, low energy, feature with a shoulder at 650 nm in the dispersion relations of the extraordinary (out-of-plane) extinction and absorption coefficients of the annealed films, which we assign to aggregate absorption. Thus, our work shows that VASE is sufficiently sensitive to measure aggregate absorption in CP films. In the case of the ordinary (in-plane) extinction and absorption coefficients, there is an increased amplitude of the lower energy peak upon heating, owing to increased uniaxial anisotropy, along with a broadening and a longer red tail, but the well-resolved red-shifted absorption band seen for the extraordinary absorption coefficient is not observed. Therefore, we conclude that while in-plane and out-of-plane aggregation occurs in annealed spin-coated films of MEH-PPV, aggregate absorption is only clearly observed when the aggregate electronic transition dipole is oriented preferentially in a direction perpendicular to the film plane. This conclusion is consistent with the usual observation that aggregate absorption in MEH-PPV films is not easily observed using absorption spectra alone, which are typically measured at normal incidence.
Large negative magnetoelectric coupling in Fe substituted ferroelectric Bi0.5Na0.5TiO3: An experimental study supported by Landau-Devonshire free-energy model based calculations
Authors: Kumari Mukesh , Agarwal Shubham , Santapuri Sushma , Chatterjee Ratnamala
Published: March 2020

This work presents an experimental and analytical study of a negative magnetoelectric (ME) effect observed in Fe substituted Bi0.5Na0.5TiO3 (BNT). Experiments are performed on solid solutions of Bi0.5Na0.5(FexTi(1 − 3x/4))O3 (BNFT), for x = 0 to 0.2, synthesized using the conventional solid state reaction route. X-ray diffraction studies confirm that Fe ions are completely soluble in a BNT matrix, up to the highest solubility of x = 0.2, thus forming a single-phase perovskite structure. As expected, partial substitution of Fe ions at Ti4+ sites diminishes the ferroelectric behavior of BNFT. For the optimal composition of x = 0.05, electrical poling of the sample results in an ∼19% decrease in magnetization, i.e., a large negative ME coupling is observed. Experimental results are supported by the Landau–Devonshire thermodynamic model based calculations for single-phase multiferroics. The model is utilized to obtain a theoretical estimate of the ME coupling coefficient of approximately −430 kV/cm Oe.
Time evolution of two harmonic oscillators with cross-Kerr interactions
Authors: Bruschi David Edward
Published: March 2020

We study the time evolution of two coupled quantum harmonic oscillators interacting through nonlinear optomechanical-like Hamiltonians that include cross-Kerr interactions. We employ techniques developed to decouple the time-evolution operator and obtain the analytical solution for the time evolution of the system. We apply these results to obtain explicit expressions of a few quantities of interest. Our results do not require approximations and therefore allow us to study the nature and implications of the full nonlinearity of the system. As a potential application, we show that it is possible to greatly increase the population of phonons using a suitable combination of cubic and cross-Kerr interactions.
Predicting observed and hidden extreme events in complex nonlinear dynamical systems with partial observations and short training time series
Authors: Chen Nan , Majda Andrew J.
Published: March 2020

Extreme events appear in many complex nonlinear dynamical systems. Predicting extreme events has important scientific significance and large societal impacts. In this paper, a new mathematical framework of building suitable nonlinear approximate models is developed, which aims at predicting both the observed and hidden extreme events in complex nonlinear dynamical systems for short-, medium-, and long-range forecasting using only short and partially observed training time series. Different from many ad hoc data-driven regression models, these new nonlinear models take into account physically motivated processes and physics constraints. They also allow efficient and accurate algorithms for parameter estimation, data assimilation, and prediction. Cheap stochastic parameterizations, judicious linear feedback control, and suitable noise inflation strategies are incorporated into the new nonlinear modeling framework, which provide accurate predictions of both the observed and hidden extreme events as well as the strongly non-Gaussian statistics in various highly intermittent nonlinear dyad and triad models, including the Lorenz 63 model. Then, a stochastic mode reduction strategy is applied to a 21-dimensional nonlinear paradigm model for topographic mean flow interaction. The resulting five-dimensional physics-constrained nonlinear approximate model is able to accurately predict extreme events and the regime switching between zonally blocked and unblocked flow patterns. Finally, incorporating judicious linear stochastic processes into a simple nonlinear approximate model succeeds in learning certain complicated nonlinear effects of a six-dimensional low-order Charney–DeVore model with strong chaotic and regime switching behavior. The simple nonlinear approximate model then allows accurate online state estimation and the short- and medium-range forecasting of extreme events.
Integrated electronics in 130 nm CMOS process for quantum key distribution sender device
Authors: Wang Xinzhe , Liang Futian , Feng Bo , Zhu Chenxi , Zhu Yulong , Jin Ge
Published: March 2020

Quantum Key Distribution (QKD) is the most mature method for implementing commercial quantum communications in practice. As part of the miniaturization of practical QKD devices, an integrated electronic system in the 130 nm complementary metal oxide semiconductor process is presented for the QKD sender device. The electronics provide driving signals for the optics at the sender terminal of the quantum channel in QKD and consist mainly of three key modules, namely, a laser diode driver with a high slew rate, a high-speed physical random number generator, and a pre-driver for the electro-optic modulator. The electronic system is designed to operate at frequencies as high as 625-MHz to accommodate the frequency of the QKD system. The high degree of integration is advantageous for miniaturizing QKD sender devices.
Design and development of a coating device: Multiple-droplet drop-casting (MDDC-Alpha)
Authors: Brian Dominikus , Eslamian Morteza
Published: March 2020

We report the development of a coating device (multiple-droplet drop-casting), which releases multiple droplets simultaneously or with a short time-lag (<10 ms) using a multi-channel syringe pump to achieve deposition of large-area (up to ∼100 cm2) and patterned coatings. The device exhibits the following features and characteristics: simple, low-cost, and scalable; adaptive to various solution-processed materials; insensitive to small contaminations/impurities; minimizes material waste; and can create patterns (printing). The demonstration of the device performance was carried out by fabricating coatings using four strategic model solutions, namely, carbon nanotube ink, graphene oxide ink, [poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)] PEDOT:PSS solution, and n-methyl-2-pyrrolidone diluted methylammonium lead iodide (CH3NH3PbI3)-based light harvesting perovskite. We investigated the effect of release height (droplet velocity or Weber number) and the film area on the film characteristics. The results show that the device yields reproducible and uniform films on the order of micrometers in thickness and ∼1 μm in roughness.
On the influence of two-dimensional hump roughness on laminar–turbulent transition
Authors: Franco Sumariva Juan Alberto , Hein Stefan , Valero Eusebio
Published: March 2020

The presence of large surface irregularities such as humps, where the height is similar to the local boundary-layer (BL) displacement thickness, introduces regions of localized strong streamwise gradients in the base flow quantities. These large gradients can significantly modify the spatial development of incoming disturbances that lead to laminar–turbulent transition in wall-bounded flows [e.g., Tollmien–Schlichting (TS) waves]. Techniques such as Parabolized Stability Equations (PSE) are not suited for BL instability analysis in such regions: their formulation assumes that streamwise variations of base flow and disturbance quantities are small, allowing a marching procedure for their resolution. On the other hand, the Adaptive Harmonic Linearized Navier–Stokes (AHLNS) equations can handle these large streamwise gradients by using a fully elliptic system of equations, similar to Linearized Navier–Stokes (LNS), Harmonic LNS (HLNS), or Direct Numerical Simulation (DNS). Moreover, in AHLNS (as in PSE), a wave-like character of the instabilities is assumed, leading to a significant reduction in the number of streamwise grid points required compared with LNS, HLNS, or DNS computations. In the present study, an efficient combination of PSE and AHLNS is used to investigate the effect of height, length, and shape of a single hump placed on a flat plate in a two-dimensional flow field at Ma∞ = 0.5 without pressure gradient. The effect of this hump on the spatial evolution of TS waves, in terms of N-factors, is presented. An expected laminar–turbulent transition onset, via the eN methodology, is also described. It is shown that the shape of the surface irregularity, together with the height and length, plays an important role for the location of laminar–turbulent transition onset in convectively unstable flows.
Magneto-transport and Shubnikov-de Haas oscillations in the layered ternary telluride topological semimetal candidate Ta3SiTe6
Authors: Naveed Muhammad , Fei Fucong , Bu Haijun , Bo Xiangyan , Shah Syed Adil , Chen Bo , Zhang Yong , Liu Qianqian , Wei Boyuan , Zhang Shuai , Guo Jingwen , Xi Chuanying , Rahman Azizur , Zhang Zengming , Zhang Minhao , Wan Xiangang , Song Fengqi
Published: March 2020

Topological semimetals characterize a unique class of quantum materials hosting Dirac/Weyl fermions. The important features of topological fermions can be exhibited by quantum oscillations. Here, we report the magnetoresistance and Shubnikov-de Haas (SdH) quantum oscillation of longitudinal resistance in the single crystal of topological semimetal candidate Ta3SiTe6 with a magnetic field up to 38 T. The periodic amplitude of the oscillations shows related information about the Fermi surface. The fast Fourier transformation spectra represent a single oscillatory frequency. The analysis of the oscillations shows the Fermi pocket with a cross sectional area of 0.13 Å−2. Combining magneto-transport measurements and the first-principles calculation, we find that these oscillations come from the hole pocket. Hall resistivity and the SdH oscillations recommend that Ta3SiTe6 is a hole dominated system.
Memristive devices based on 2D-BiOI nanosheets and their applications to neuromorphic computing
Authors: Wang Hong , Yan Xiaobing , Zhao Mengliu , Zhao Jianhui , Zhou Zhenyu , Wang Jingjuan , Hao Weichang
Published: March 2020

Memristors are considered to being one of the key devices that are expected to break through traditional von-Neumann computing architectures and are used to simulate bio-synapse in neural computing networks. In this work, we fabricated a high quality two-dimensional BiOI (2D-BiOI) nanosheet film by the hydrolysis method and constructed a Ti/2D-BiOI/FTO memristor. Meanwhile, the typical resistive switching characteristics and the functions of biomimetic synapses of the device were studied. The devices exhibit about +1.17/−1.62 V SET/RESET voltages, over 1.4 × 104 s retention, and excellent anti-fatigue properties. Simultaneously, the learning and memory functions, such as spiking-time-dependent plasticity, paired pulse facilitation, short-term plasticity, and short-term plasticity, might be simulated. The resistance switching mechanism is believed to be mainly related to the formation and destruction of oxygen vacancy filament channels by the analysis of XPS depth profiling. The device based on 2D-BiOI films possesses promising potential application in neuromorphic chip systems.
Regenerative cooling using elastocaloric rubber: Analytical model and experiments
Authors: Sebald Gael , Komiya Atsuki , Jay Jacques , Coativy Gildas , Lebrun Laurent
Published: March 2020

Caloric materials exhibit significant entropy variations when applying appropriate excitation, pushing forward the development of solid-state cooling systems. Their development includes materials' properties optimization, with a focus on their adiabatic temperature change when driven at their limit. In order to sustain the device development, an analytical model for regenerative cooling systems is presented in this work. It consists of a caloric material driven cyclically so that it exhibits harmonic temperature variations, whereas an oscillating fluid layer is exchanging heat with the caloric material, leading to a net heat flux along one given direction. The heat transfer equation was solved analytically for harmonic excitations along the direction perpendicular to caloric material layers separated by fluid layers. In the second step, the problem was solved along an axis parallel to the layers. In order to validate the model, an experimental proof of concept was developed based on a natural rubber tube inside which water flows harmonically. The comparison between the model and experiment is given, while the model highlights the importance of the thermal boundary layer and how the geometry of the device easily compensates for the low thermal conductivity of natural rubber.
A high power laser facility to conduct annealing tests at high temperature
Authors: Minissale M. , Durif A. , Hiret P. , Vidal T. , Faucheux J. , Lenci M. , Mondon M. , Kermouche G. , Pontillon Y. , Grisolia C. , Richou M. , Gallais L.
Published: March 2020

The knowledge of material properties and their behavior at high temperatures is of crucial importance in many fields. For instance, annealing phenomena occurring during the thermomechanical processing of materials, such as recrystallization, have long been recognized as being both of scientific interest and technological importance. Different methods are currently used to study annealing phenomena and submit metals to heat loads. In this work, we present the design and the development of a laser-based facility for annealing tests. This experimental setup enables studies at the laboratory scale with great flexibility to submit samples to various spatial and temporal heating profiles. Due to the possibility of having optical access to the sample, laser heating can be combined with several non-contact diagnostics such as infrared imaging to control and analyze the temperature gradients. As a case study, we present a set of experiments performed to study the recrystallization kinetics of tungsten. We demonstrate that samples can be heated linearly with heating rate up to ∼2000 K/s, at temperatures above 2000 K, for seconds or hours, with typical errors in the temperature measurement of around 1% that depend mainly on the determination of sample emissivity. Such studies are of crucial interest in the framework of nuclear fusion since the international thermonuclear experimental reactor nuclear reactor will operate with a full-W divertor.
Results and model for single-gate ratchet charge pumping
Authors: Murray Roy , Perron Justin K. , Stewart M. D. , Levy Antonio L. , See Patrick , Giblin Stephen P. , Fletcher Jonathan D. , Kataoka Masaya , Zimmerman Neil M.
Published: March 2020

We show experimentally that, in the same Si devices, we can demonstrate multiple two-gate pumping modes but not single-gate mode. We contrast this with GaAs devices, which do show single-gate pumping at a high yield. We propose four mechanisms to explain the lack of plateaus in the Si devices in single-gate ratchet mode: operating the dot with a large number of electrons, a large ratio between the change in electrochemical potential energy and the change in the energy of the barrier (plunger-to-barrier ratio, Δptb) compared to the charging energy (Δptb/EC), nonlinear tunnel barriers, and phase offset leading to nonequilibrium heating. Our analysis shows that each of these could contribute to the lack of plateaus in single-gate ratchet pumping on Si devices but allow two-gate pumping methods to work with robust plateaus. It is easier for GaAs pumps to avoid these failure mechanisms due to their different architectures and cleaner gate turnoff curves. We propose several methods to reduce these sources of error, including reducing cross capacitances between gates. These recommendations may prove useful to other researchers in producing more robust, higher yield single-gate ratchet pumps.
Event synchrony measures for functional climate network analysis: A case study on South American rainfall dynamics
Authors: Wolf Frederik , Bauer Jurek , Boers Niklas , Donner Reik V.
Published: March 2020

Understanding spatiotemporal patterns of climate extremes has gained considerable relevance in the context of ongoing climate change. With enhanced computational capacity, data driven methods such as functional climate networks have been proposed and have already contributed to significant advances in understanding and predicting extreme events, as well as identifying interrelations between the occurrences of various climatic phenomena. While the (in its basic setting) parameter free event synchronization (ES) method has been widely applied to construct functional climate networks from extreme event series, its original definition has been realized to exhibit problems in handling events occurring at subsequent time steps, which need to be accounted for. Along with the study of this conceptual limitation of the original ES approach, event coincidence analysis (ECA) has been suggested as an alternative approach that incorporates an additional parameter for selecting certain time scales of event synchrony. In this work, we compare selected features of functional climate network representations of South American heavy precipitation events obtained using ES and ECA without and with the correction for temporal event clustering. We find that both measures exhibit different types of biases, which have profound impacts on the resulting network structures. By combining the complementary information captured by ES and ECA, we revisit the spatiotemporal organization of extreme events during the South American Monsoon season. While the corrected version of ES captures multiple time scales of heavy rainfall cascades at once, ECA allows disentangling those scales and thereby tracing the spatiotemporal propagation more explicitly.
Angular scattering of protons through ultrathin graphene foils: Application for time-of-flight instrumentation
Authors: Vira Alisha D. , Fernandes Philip A. , Funsten Herbert O. , Morley Steven K. , Yamaguchi Hisato , Liu Fangze , Moody Nathan A.
Published: March 2020

Space plasma instruments often rely on ultrathin carbon foils for incident ion detection, time-of-flight (TOF) mass spectrometry, and ionization of energetic neutral atoms. Angular scattering and energy loss of ions or neutral atoms in the foil can degrade instrument performance, including sensitivity and mass resolution; thus, there is an ongoing effort to manufacture thinner foils. Using new 3-layer graphene foils manufactured at the Los Alamos National Laboratory, we demonstrate that these are the thinnest foils reported to date and discuss future testing required for application in space instrumentation. We characterize the angular scattering distribution for 3–30 keV protons through the foils, which is used as a proxy for the foil thickness. We show that these foils are ∼2.5–4.5 times thinner than the state-of-the-art carbon foils and ∼1.6 times thinner than other graphene foils described in the literature. We find that the inverse relationship between angular scattering and energy no longer holds, reaffirming that this may indicate a new domain of beam–foil interactions for ultrathin (few-layer) graphene foils.
Effect of interfacial mass transport on inertial spreading of liquid droplets
Authors: Baroudi Lina , Lee Taehun
Published: March 2020

In this work, the early time dynamics of low-viscosity liquid drops spreading in their saturated vapor on partially wetting surfaces are investigated by lattice Boltzmann numerical simulations. Attention is paid to the effect of vapor transport through condensation on the spreading process. We observe that the condensation current resulting from the slight supersaturation of the liquid vapor near the dynamic wetting meniscus contributes to the motion and affects the spreading dynamics. Our results indicate that, in order to properly capture the initial dynamics of inertial spreading of a relatively volatile liquid drop, it is important to account for the vapor transport through condensation in the immediate vicinity of the contact line. A direct qualitative and quantitative comparison with experimental data of spontaneously wetting liquid drops is presented.
Mechanisms of energetic-particle transport in magnetically confined plasmas
Authors: Heidbrink W. W. , White R. B.
Published: March 2020

Super-thermal ions and electrons occur in both space and fusion plasmas. Because these energetic particles (EP) have large velocities, EP orbits necessarily deviate substantially from magnetic surfaces. Orbits are described by conserved constants of motion that define topological boundaries for different orbit types. Electric and magnetic field perturbations produced by instabilities can disrupt particle orbits, causing the constants of motion to change. The statistics of the “kicks” associated with these perturbations determines the resulting cross field transport. A unifying theme of this tutorial is the importance of the perturbation’s phase at the particle’s position Θ=k·r−ωt, where k and ω are the wavevector and frequency of the perturbation, r is the EP position, and t is the time. A distinction is made between field perturbations that resonate with an aspect of the orbital motion and those that do not. Resonance occurs when the wave phase returns to its initial value in an integer multiple of an orbital period. Convective transport occurs when resonant particles experience an unvarying wave phase. Alternatively, multiple wave-particle resonances usually decorrelate the phase, resulting in diffusive transport. Large orbits increase the number of important resonances and can cause chaotic orbits even for relatively small amplitude waves. In contrast, in the case of non-resonant perturbations, orbital phase averaging reduces transport. Large field perturbations introduce additional effects, including nonlinear resonances at fractional values of the orbital motion. In summary, large orbits are a blessing and a curse: For non-resonant modes, orbit-averaging reduces transport but, for resonant transport, large orbits facilitate jumps across topological boundaries and enhance the number of important resonances.
Long-range-corrected multiconfiguration density functional with the on-top pair density
Authors: Hapka Michał , Pastorczak Ewa , Krzemińska Agnieszka , Pernal Katarzyna
Published: March 2020

We propose a multiconfiguration density functional combining a short-range density functional approximation with a novel long-range correction for dynamic correlation effects. The correction is derived from the adiabatic connection formalism so that the resulting functional requires access only to one- and two-electron reduced density matrices of the system. In practice, the functional is formulated for wavefunctions of the complete active space (CAS) type and the short-range density functional part is made dependent on the on-top pair density via auxiliary spin densities. The latter allows for reducing the self-interaction and the static correlation errors without breaking the spin symmetry. We study the properties and the performance of the non-self-consistent variant of the method, termed lrAC0-postCAS. Numerical demonstration on a set of dissociation energy curves and excitation energies shows that lrAC0-postCAS provides accuracy comparable with more computationally expensive ab initio rivals.
Widening the criteria for emergence of Turing patterns
Authors: Kuznetsov Maxim , Polezhaev Andrey
Published: March 2020

The classical concept for emergence of Turing patterns in reaction–diffusion systems requires that a system should be composed of complementary subsystems, one of which is unstable and diffuses sufficiently slowly while the other one is stable and diffuses sufficiently rapidly. In this work, the phenomena of emergence of Turing patterns are studied and do not fit into this concept, yielding the following results. (1) The criteria are derived, under which a reaction–diffusion system with immobile species should spontaneously produce Turing patterns under any diffusion coefficients of its mobile species. It is shown for such systems that under certain sets of types of interactions between their species, Turing patterns should be produced under any parameter values, at least provided that the corresponding spatially non-distributed system is stable. (2) It is demonstrated that in a reaction–diffusion system, which contains more than two species and is stable in absence of diffusion, the presence of a sufficiently slowly diffusing unstable subsystem is already sufficient for diffusion instability (i.e., Turing or wave instability), while its complementary subsystem can also be unstable. (3) It is shown that the presence of an immobile unstable subsystem, which leads to destabilization of waves within an infinite range of wavenumbers, in a spatially discrete case can result in the generation of large-scale stationary or oscillatory patterns. (4) It is demonstrated that under the presence of subcritical Turing and supercritical wave bifurcations, the interaction of two diffusion instabilities can result in the spontaneous formation of Turing structures outside the region of Turing instability.
Fundamental limits of jumping droplet heat transfer
Authors: Foulkes Thomas , Sett Soumyadip , Sokalski Peter , Oh Junho , Miljkovic Nenad
Published: March 2020

Liquid-vapor phase-change cooling has a significant potential to facilitate the development of highly dense electronics by leveraging latent heat during the phase transition to remove heat from hotspots. A promising form of liquid–vapor phase-change cooling is coalescence-induced jumping droplet condensation, where droplet growth results in coalescence and gravity-independent jumping from the cold surface due to capillary-inertial energy conversion. Once the departed droplets reach the hotspot, heat is extracted via evaporation and through vapor return, subsequently spreading to the cold surface via condensation. Realizing the full potential of jumping droplet cooling requires a detailed understanding of the physics governing the process. Here, we examine the fundamental thermal and hydrodynamic limits of jumping droplet condensation. We demonstrate that jumping is mainly governed by the rate of droplet growth and fluid thermophysical properties. Timescale analysis demonstrates that the upper bound of water vapor jumping droplet condensation critical heat flux is ∼ 20 kW/cm2, significantly higher than that experimentally observed thus far due to surface structure limitations. Analysis of a wide range of available working fluids shows that liquid metals such as Li, Na, and Hg can obtain superior performance when compared to water.
Magneto-fibrillation augments the breakdown strength of ferrofluid dielectrics
Authors: Dhar Purbarun
Published: March 2020

The present article reports experimental evidence with a theoretical formalism on the enhancement of the dielectric breakdown strength of ferrofluids by inducing magneto-fibrillation with an external magnetic field. The dielectric breakdown strengths of oil based ferrofluids are determined, and it is further shown that the strength enhances due to the presence of a localized magnetic field in the streamer development zones. The improvement in breakdown strength is also supplemented by improvement in the reliability of the liquid dielectrics, which is established by a two parameter Weibull analysis. It is also noted that a horizontal magnetic field is more potent toward improved breakdown strength than an equivalent vertical field. The enhanced scavenging of electrons from the streamer development zones due to localized magnetic fibrillation by the nanoparticles is proposed as the crux mechanism. Microscopy studies are conducted to provide visual evidence of the fibrillation process in the ferrofluids due to the local magnetic field. A theoretical formalism is proposed to predict the ferrohydrodynamics of fibrillation, and this is further used to develop a model to predict the increment in breakdown strengths. The proposed model predictions are noted to agree well with the experimental observations. The study may find strong implications in design and development of high voltage liquid dielectrics with tunable electrical stress bearing caliber.
The asymptotic behavior of the time fractional Schrödinger equation on Hilbert space
Authors: Górka Przemysław , Prado Humberto , Pons Daniel J.
Published: March 2020

The purpose of this article is to show the asymptotic behavior of the solution of the abstract Schrödinger equation with time fractional derivative of order α ∈ (0, 1). We give a detailed description of the long time behavior of the corresponding operator solution. As it is expected in this case, the dynamics are not governed neither by a group nor by a semigroup.
Forevacuum-pressure plasma-cathode high-power continuous electron beam source
Authors: Zenin A. A. , Bakeev I. Yu. , Klimov A. S. , Oks E. M. , Tran Van Tu
Published: March 2020

We describe a plasma-cathode electron beam source based on a hollow-cathode discharge that is capable of generating a 9 kW dc electron beam at an accelerating voltage of 20 kV, with helium as a working gas at a pressure of 30 Pa. A test run of ∼50 operational hours did not indicate any significant degradation of the electron source extraction system or other structural components, and we estimate the operational lifetime of the source at about 100–120 h.
EWOD-aided droplet transport on texture ratchets
Authors: Sun Di , Böhringer Karl F.
Published: March 2020

We report a digital microfluidic device to transport aqueous droplets on an open surface in air using electrowetting-on-dielectric (EWOD) with anisotropic ratchet conveyors (ARCs). ARCs are micro-sized periodic semicircular hydrophilic regions on a hydrophobic background, providing anisotropic wettability. SiNx and Cytop are used as the dielectric layer between the water droplet and working electrodes. By adopting parylene as a stencil mask, hydrophilic patterning on the hydrophobic Cytop thin film layer is achieved without the loss of Cytop hydrophobicity. While the traditional EWOD platform requires the control of multiple electrodes to transport the droplet, our system utilizes only two controlling electrodes. We demonstrate that 15 μl water droplets are transported at a speed of 13 mm/s under 60 Vpeak sinusoid AC signal at 50 Hz. Droplet transport at 20 Hz is also presented, demonstrating that the system can operate within a range of frequencies.
Magnetic field-controlled −π transitions and their experimental signatures in superconductor-ferromagnet-superconductor junctions
Authors: Vargunin A. , Silaev M. A.
Published: March 2020

Superconductor-ferromagnet-superconductor Josephson junctions are known to exist in the 0 and π states with the transitions between them controlled by the temperature and ferromagnetic interlayer thickness. We demonstrate that these transitions can be controlled also by the external magnetic field directed perpendicular to the layers. By varying the ratio of diffusion coefficients in superconducting and ferromagnetic layers, these field-controlled transitions can be made detectable for arbitrary large values of the exchange energy in the ferromagnet. We also show that the 0−π transitions in the perpendicular field can be observed as the specific features of the flux-flow conductivity dependencies on the ferromagnetic thickness in accordance with recent experimental results.
The current modulation of anomalous Hall effect in van der Waals Fe3GeTe2/WTe2 heterostructures
Authors: Shao Yan , Lv Wenxing , Guo Junjie , Qi Baotao , Lv Weiming , Li Shangkun , Guo Guanghua , Zeng Zhongming
Published: March 2020

The recent discovery of magnetic two-dimensional (2D) crystals offers a platform to study the spin-related phenomena in van der Waals (vdW) heterostructures. Here, we investigate the anomalous Hall effect in the bilayer all-vdW heterostructure of Fe3GeTe2 (FGT)/WTe2. In such devices, the coercivity of thin-FGT flakes can be effectively modulated by the current, which is mainly attributed to the Joule heating effect generated at the interface of the FGT/WTe2 bilayer because of the low interfacial thermal conductance. The gradient ΔHc/ΔJFGT is as large as 0.55 kOe MA−1 cm2 at 10 K. Our work provides great guidance for the design of next generation spintronic devices based on atomically thin van der Waals heterostructures.
Correlation between the temperature evolution of the interfacial region and the growing dynamic cooperativity length scale
Authors: Cheng Shiwang , Sokolov Alexei P.
Published: March 2020

We study experimentally the temperature evolution of the thickness of the interfacial layer, Lint(T), between bulk matrices and the surface of nanoparticles in nanocomposites through broadband dielectric spectroscopy. Analyses revealed a power-law dependence between the logarithm of structural relaxation time in the interfacial layer, τint(T), and the Lint(T): lnτint(T)/τ0∝Lintβ(T)/T, with τ0 ∼ 10−12 s, and β index ∼0.67 at high temperatures and ∼1.7 at temperatures close to the glass transition temperature. In addition, our analysis revealed that the Lint(T) is comparable to the length scale of dynamic heterogeneity estimated from previous nonlinear dielectric measurements and the four-point NMR [ξNMR(T)], with Lint(T) ∼ ξNMR(T). These observations may suggest a direct correlation between the Lint(T) and the size of the cooperatively rearranging regions and have strong implications for understanding the dynamic heterogeneity and cooperativity in supercool liquids and their role in interfacial dynamics.
Polarizable molecular dynamics simulations of ionic liquids: Influence of temperature control
Authors: Heid Esther , Boresch Stefan , Schröder Christian
Published: March 2020

Ionic liquids are an interesting class of soft matter with viscosities of one or two orders of magnitude higher than that of water. Unfortunately, classical, non-polarizable molecular dynamics (MD) simulations of ionic liquids result in too slow dynamics and demonstrate the need for explicit inclusion of polarizability. The inclusion of polarizability, here via the Drude oscillator model, requires amendments to the employed thermostat, where we consider a dual Nosé–Hoover thermostat, as well as a dual Langevin thermostat. We investigate the effects of the choice of a thermostat and the underlying parameters such as the masses and force constants of the Drude particles on static and dynamic properties of ionic liquids. Here, we show that Langevin thermostats are not suitable for investigating the dynamics of ionic liquids. Since polarizable MD simulations are associated with high computational costs, we employed a self-developed graphics processing unit enhanced code within the MD program CHARMM to keep the overall computational effort reasonable.
Surface wave mechanism for directional motion of droplet on an obliquely vibrated substrate
Authors: Guo Jiao-Jiao , Chen Xiao-Peng , Shui Langquan
Published: March 2020

The directional motion of a two-dimensional droplet on an obliquely vibrated substrate is studied numerically. The time dependent droplet profile is decomposed by using a proper orthogonal decomposition (POD) method. Two dominant POD modes of the capillary wave are identified. The first mode is quasi-harmonic, which leads to an apparent wetted area difference between uphill and downhill stages of the substrate vibration (ΔS). It plays a key role in the directional motion. The second mode is weak but contributes to ΔS subtly. The two modes qualitatively match the proposed “swaying” and “spreading” modes. Our decomposition directly reveals the connection between ΔS and the surface waves.
Nonlinear evolution of perturbations in high Mach number wall-bounded flow: Pressure–dilatation effects
Authors: Mittal Ankita , Girimaji Sharath S.
Published: March 2020

We characterize the nonlinear evolution of perturbations in a high Mach number Poiseuille flow and contrast the behavior against an equivalent incompressible flow. The focus is on the influence of pressure–dilatation on (i) internal energy evolution, (ii) kinetic–internal energy exchange, and (iii) kinetic energy spectrum evolution. We perform direct numerical simulations of plane Poiseuille flow at different Mach numbers subject to a variety of initial perturbations. In all high-speed cases considered, pressure dilatation leads to energy equipartition between wall-normal velocity fluctuations (dilatational kinetic energy) and pressure fluctuations (a measure of internal energy). However, the effect of pressure–dilatation on the kinetic energy spectral growth can be varied. In cases wherein pressure–dilatation is larger than the turbulent kinetic energy production, spectral growth is considerably slow relative to an equivalent low Mach number case. When pressure–dilatation is smaller than production, the spectral growth is only marginally affected. As a consequence, in a high-speed Poiseuille flow, the spectral growth rate varies with the wall-normal distance depending on the local pressure effects. These findings provide valuable insight into the nonlinear aspects of breakdown toward turbulence in high speed wall-bounded shear flows.
Viscoelastic laminar drag bounds in pipe flow
Authors: Malik M. , Bouffanais Roland , Skote Martin
Published: March 2020

The velocity and friction properties of laminar pipe flow of a viscoelastic solution are bounded by the corresponding values for two Newtonian fluids, namely, the solvent and a fluid with a viscosity identical to the total viscosity of the solution. The lower friction factor for the flow of the solution when compared to the latter is tracked to an increased strain rate needed to enhance viscous dissipation. Finally, we show analytically that the effective viscosity varies similarly to the radial diagonal component of the conformation tensor as observed numerically in turbulent flows and give a lucid interpretation of shear-thinning through a sequence of underlying constitutive physical phenomena.
Experimental and theoretical studies of the doubly substituted methyl-ethyl Criegee intermediate: Infrared action spectroscopy and unimolecular decay to OH radical products
Authors: Barber Victoria P. , Hansen Anne S. , Georgievskii Yuri , Klippenstein Stephen J. , Lester Marsha I.
Published: March 2020

The infrared (IR) action spectrum of the doubly substituted methyl-ethyl Criegee intermediate (MECI) is observed in the CH stretch overtone region with detection of OH products. The MECI exhibits four conformers, all of which undergo unimolecular decay via a 1,4 H-atom transfer mechanism, followed by the rapid release of OH products. Conformers with different orientations of the carbonyl oxide group with respect to the methyl and ethyl substituents (i.e., anti and syn) decay via distinct transition state barriers (16.1 kcal mol−1 and 15.4 kcal mol−1, respectively). The observed IR action spectrum is in good agreement with the predicted anharmonic IR absorption spectrum, but exhibits significant congestion, which is attributed to couplings between spectroscopic bright states and nearby dark states. Energy-dependent OH appearance rates are measured upon IR excitation of the strongest features in the IR action spectrum and are found to be on the order of 106–107 s−1. The experimental rates are in good agreement with computed Rice–Ramsperger–Kassel–Marcus rates for the unimolecular decay of MECI at these energies, which incorporate quantum mechanical tunneling and sophisticated hindered rotor treatments, as well as high-level theoretical calculations of the TS barrier heights, rovibrational properties, and torsional barriers associated with the MECI conformers. Master equation modeling is used to predict thermal rates for the unimolecular decay of anti- and syn-MECI of 473 s−1 and 660 s−1, respectively. Comparison with other previously studied Criegee intermediate systems provides insights into substituent effects on unimolecular decay under both energy-dependent and thermal conditions.
Seasonal alteration in sward height of Marandu palisade grass (Brachiaria brizantha) pastures managed by continuous grazing interferes with forage production
Authors: Terra Suleize , de Andrade Gimenes Flávia Maria , Giacomini Alessandra Aparecida , Gerdes Luciana , Manço Marisa Xavier , de Mattos Waldssimiler Teixeira , Batista Karina
Published: March 2020

Changes in sward height of pastures managed by continuous grazing according to climatic seasonality may alter tillering and forage production. In order to evaluate the feasibility of seasonal alteration in sward height of Marandu palisade grass pastures (Brachiaria brizantha (Hochst. ex A.Rich.) R.D. Webster; syn. Urochloa brizantha (A.Rich.) Stapf) under continuous grazing management, we studied two constant sward heights (15 cm and 30 cm), and one height that was initiated at 30 cm, reduced to 15 cm in June (dry and cold season) and returned to 30 cm in December (wet and hot season) (30–15–30 cm). Pastures managed at 30–15–30 cm had a greater tiller appearance rate (22 tillers/100 tillers.30 days) than those maintained at 15 cm and 30 cm (16 and 17 tillers/100 tillers.30 days, respectively). In the 30–15–30 cm pastures, a lower accumulation rate of dead material was observed during the dry and cold season (June–August), which resulted in a higher leaf and lower dead material accumulation rate during the second growth season (wet and hot season, December–January). Planned reduction in sward height during the cold season can be used safely because it permits better seasonal distribution and utilisation of forage production without compromising the stability of Marandu palisade grass pastures.
English Resultatives
Authors: Iwata Seizi
Published: March 2020

The objective of this book is to develop a force-recipient account of English resultatives. Within this approach the post-verbal NP is a recipient of a verbal force, whether it is a subcategorized object or not, and the verbal force being exerted onto the post-verbal NP is responsible for bringing about the change as specified by the result phrase. It is shown that many apparent puzzles posed by English resultatives are due to the complex interplay between the verb meaning and the constructional meaning, or between the verb meaning and the semantics of the result phrase. Thus the proposed account can provide answers to the question “Which resultatives are possible and which are not?” in a coherent way. Also, the proposed account reveals that English resultatives are not a monolithic phenomenon, and that some “resultatives” cited in the literature as such are not resultatives at all. This book is of interest not only to practitioners of Construction Grammar but also to everyone interested in English resultatives.
‘Body’ and the relationship between verb and participants
Authors: Frajzyngier Zygmunt
Published: March 2020

Heine and Kuteva (2004) list ‘reflexive’, ‘middle’, and ‘reciprocal’ as functions grammaticalized from the noun ‘body’ across languages. The present study, based on data from Pero (West Chadic), demonstrates the grammaticalization of one additional function, namely that of indicating that the object of the verb does not undergo a change in form, place, existential status (emergence or disappearance), or internal state. Most of the natural data indicates that the object in question is either a human or a story character with human attributes. The existence of this function in turn allows us to explain when third person object pronouns are used in Pero and when they are not used. The use of object pronouns is the outcome of the coding of semantic relations between the verbal predicate and arguments.