bluuebunny/crossref_metadata_2025 huggingface dataset:
Meniere’s Disease: New Frontiers in Management for Better Results
Authors: Velusamy Anand , Anand Aiswarya , Janarthanan Sridurga
Published: March 2021

Introduction Meniere's disease (MD) remains a difficult disease to diagnose, especially in the early stages when not all of the symptoms may be present. Sensorineural hearing loss, tinnitus, and recurrent vertigo constitute the hallmark symptoms of MD. Endolymphatic hydrops (EH) has been described as the responsible pathology in MD. Since that description, the medical and surgical treatment of MD have been directed at reducing the volume of endolymph. Unfortunately, these approaches have had equivocal success in the control of vertigo and recovery of hearing. So, a routine treatment directed at resolution of EH may not be suitable for all patients. Treatment has to be directed at the cause of EH whenever possible.

Objectives The aim of this study was to define new findings in clinical tests and modes of treatment in MD, to determine the outcome of vertigo and hearing in patients after treatment, and to describe treatment which will prevent long term deterioration of hearing.

Materials and Methods Forty-six new patients with a diagnosis of MD were treated with antiviral drugs or diuretics. Drugs were used based on nature of dehydration test. Hearing test including pure tone average (PTA) and speech discrimination (SD) was performed prior to treatment and at 1 to 2 months, 6 months, and 1 year after initiation of treatment. Effect on dizziness was recorded at each evaluation; hearing was judged to be improved, if PTA was lowered by at least 10 to 15 dB or an increase in SD > 20%.

Results The antiviral approach has virtually eliminated the use of various surgical methods used in the past. Dehydration test-based treatment protocol with diuretics and antivirals and antimigraine prophylaxis when needed has led to remission of disease in 93.5% of patients. With prompt treatment, inner ear damage can be prevented.

Conclusion Orally administered antiviral drugs should be considered in the treatment of MD. Migraine-associated MD patients need migraine prophylaxis and this will lead to improvement in Meniere’s symptoms also. If Intratympanic therapy is considered, then targeted low-dose delivery method of using Gelfoam instillation of gentamicin is preferable according to our study to prevent any significant hearing loss.
COVID-19 in an Asymptomatic Renal Transplant Recipient Employed in the Health Care Setting: A Case Report
Authors: Adnani Harsha , Khatri Akshay , Agrawal Nirav , Molmenti Ernesto , Bhaskaran Madhu
Published: March 2021

During the ongoing pandemic, there have been varying presentations of coronavirus disease 2019 (COVID-19) infection, with the concern that patients who are immunosuppressed (due to underlying medical conditions and/or therapies) are at higher risk of severe disease. We report the case of an elderly renal transplant recipient working in a long-term health care facility who was being monitored by weekly surveillance testing and tested positive for COVID-19 by polymerase chain reaction (PCR) testing, despite having no clinical symptoms. He recovered with supportive care, despite being on multiple long-term immunosuppressant drugs and having multiple comorbidities. Additionally, it was found that he did not mount an antibody response, when he tested negative by serologic testing. Through this case, we wish to highlight the unique clinical scenario of asymptomatic patients who may have an underwhelming immune response to COVID-19, but may nevertheless be an important source of dissemination. We further discuss the probable mechanism of such asymptomatic presentations in immunosuppressed patients, while reinforcing the importance of self-isolation of COVID-19 patients (particularly in asymptomatic health care workers).
Ultra-wide bandgap corundum-structured p-type
α
-(Ir,Ga)2O3 alloys for
α
-Ga2O3 electronics
Authors: Kaneko Kentaro , Masuda Yasuhisa , Kan Shin-ichi , Takahashi Isao , Kato Yuji , Shinohe Takashi , Fujita Shizuo
Published: March 2021

Ultra-wide bandgap p-type α-(Ir,Ga)2O3 films with bandgaps of up to 4.3 eV have been obtained by unintentional doping or Mg doping. For Mg-doped films, Hall-effect measurements revealed a hole concentration of 9.9 × 1018 to 8.1 × 1019 cm−3 and a mobility of 0.13 − 0.92 cm2/V s, respectively. A preliminary test of a pn junction diode composed of p-type α-(Ir,Ga)2O3 and n-type α-Ga2O3 did not show catastrophic breakdown in the reverse direction until 100 V and the current on/off ratio at +3 V/−3V was 5 × 105. Since α-(Ir,Ga)2O3 and α-Ga2O3 take the same crystal structure and are well lattice-matched (with a lattice mismatch of <0.3%), the formation of a high-quality pn heterojunction is encouraged; this is one of the advantages of the corundum material system.
Absolute response of a Fuji BAS-TR imaging plate to low-energy protons (<0.2 MeV) and carbon ions (<1 MeV)
Authors: Kojima Sadaoki , Miyatake Tatsuhiko , Inoue Shunsuke , Dinh Thanh Hung , Hasegawa Noboru , Mori Michiaki , Sakaki Hironao , Nishiuchi Mamiko , Dover Nicholas P. , Yamamoto Yoichi , Sasaki Teru , Ito Fuyumi , Kondo Kotaro , Yamanaka Takashi , Hashida Masaki , Sakabe Shuji , Nishikino Masaharu , Kondo Kiminori
Published: March 2021

This paper reports on the absolute response of a Fuji BAS-TR image plate to relatively low-energy protons (<0.2 MeV) and carbon ions (<1 MeV) accelerated by a 10-TW-class compact high-intensity laser system. A Thomson parabola spectrometer was used to discriminate between different ion species while dispersing the ions according to their kinetic energy. Ion parabolic traces were recorded using an image plate detector overlaid with a slotted CR-39 solid-state detector. The obtained response function for the protons was reasonably extrapolated from previously reported higher-ion-energy response functions. Conversely, the obtained response function for carbon ions was one order of magnitude higher than the value extrapolated from previously reported higher-ion-energy response functions. In a previous study, it was determined that if the stopping range of carbon ions is comparable to or smaller than the grain size of the phosphor, then some ions will provide all their energy to the binder resin rather than the phosphor. As a result, it is believed that the imaging plate response will be reduced. Our results show good agreement with the empirical formula of Lelasseux et al., which does not consider photo-stimulated luminescence (PSL) reduction due to the urethane resin. It was shown that the PSL reduction due to the deactivation of the urethane resin is smaller than that previously predicted.
An 18.3 MJ charging and discharging pulsed power supply system for the Space Plasma Environment Research Facility (SPERF): Modular design method and component selection
Authors: E Peng , Guan Jian , Ling Wenbin , Ma Xun , Mao Aohua , Deng Weijun , Ding Mingjun , Li Songjie , Kang Chuanhui , Li Hongtao
Published: March 2021

The capacitor-based pulsed power supply (PPS) system is an important subsystem of the Space Plasma Environment Research Facility being built as a user facility at Harbin Institute of Technology in China. It has been developed with a modular design to drive magnetic coils to generate magnetic fields and plasma for the physical experiments. In this paper, the modular design and component selection are proposed based on a calculation of parameter ranges of components and the number of modules followed by a simulation and an engineering test. Both the simulation and test results show the feasibility of the selected components and the number of modules to meet the designing requirements of the PPS.
How to build coarse-grain transport models consistent from the kinetic to fluid regimes
Authors: Torres Erik , Bellas-Chatzigeorgis Georgios , Magin Thierry E.
Published: March 2021

In this paper, we examine how to build coarse-grain transport models consistently from the kinetic to fluid regimes. The internal energy of the gas particles is described through a state-to-state approach. A kinetic equation allows us to study transport phenomena in phase space for a non-homogeneous gas mixture. Internal energy excitation is modeled using a binary collision operator, whereas gas chemical processes rely on a reactive collision operator. We obtain an asymptotic fluid model by means of a Chapman–Enskog perturbative solution to the Boltzmann equation in the Maxwellian reaction regime. The macroscopic conservation equations of species mass, mixture momentum, and energy as well as expressions of the transport properties are given. Reversibility relations for elementary processes are formulated in the coarse-grain model at the kinetic level and are enforced in the collision algorithm of the direct simulation Monte Carlo method used to solve the kinetic equation. Furthermore, respecting these reversibility relations is key to deriving a fluid model that is well-posed and compatible with the second law of thermodynamics. The consistency between the kinetic and fluid simulations is assessed for the simulation of a shock wave in a nitrogen gas using the uniform rovibrational collisional coarse-grain model. The kinetic and fluid simulations show consistency for the macroscopic properties and transport fluxes between both regimes.
Thermo-kinetic explosions: Safety first or safety last?
Authors: Cartwright Julyan H. E.
Published: March 2021

Gas and vapor explosions have been involved in industrial accidents since the beginnings of industry. A century ago, at 11:55 am on Friday September 24, 1920, the petroleum barge Warwick exploded in London's docklands and seven men were killed. Understanding what happened when it blew up as it was being refurbished, and how to prevent similar explosions, involves fluid mechanics and thermodynamics plus chemistry. I recount the 1920 accident as an example, together with the history of thermo-kinetic explosions prior to 1920 and up to the present day, and I review the history and the actual state of the science of explosion and the roles of fluid mechanics, thermodynamics, and chemistry in that science. The science of explosions has been aware of its societal implications from the beginning, but, despite advances in health and safety over the past century, is there still work to do?
Computational modeling of three-dimensional thermocapillary flow of recalcitrant bubbles using a coupled lattice Boltzmann-finite difference method
Authors: Mitchell T. R. , Majidi M. , Rahimian M. H. , Leonardi C. R.
Published: March 2021

This study analyzes the thermocapillary flow of recalcitrant bubbles within thin channels using a hybrid finite difference lattice Boltzmann method (LBM). It extends a recently developed phase-field LBM to account for temperature effects by coupling the scheme with a fourth-order Runge–Kutta algorithm to solve the governing energy equation. The LBM makes use of a weighted-multiple relaxation-time collision scheme, which has been previously shown to capture high density and viscosity contrasts. This paper makes contributions in two fundamental areas relating to thermocapillary flow. First, it presents and verifies a novel, three-dimensional model to resolve thermocapillary dynamics for practical applications. The verification was undertaken via comparison with analytical solutions for the flow of immiscible fluids in a heated microchannel and for the migration of a droplet in a temperature field. Second, it provides new insight into the inherently three-dimensional nature of recalcitrant bubbles. It was found that the competing inertial and thermal effects allow these bubbles to propagate against the bulk motion of the liquid toward regions of low surface tension.
Influence of substrate-induced thermal stress on the superconducting properties of V3Si thin films
Authors: Vethaak T. D. , Gustavo F. , Farjot T. , Kubart T. , Gergaud P. , Zhang S.-L. , Nemouchi F. , Lefloch F.
Published: March 2021

Thin films of superconducting V3Si were prepared by means of RF sputtering from a compound V3Si target at room temperature onto sapphire and oxide-coated silicon wafers, followed by rapid thermal processing under secondary vacuum. The superconducting properties of the films thus produced are found to improve with annealing temperature, which is ascribed to a reduction in defects in the polycrystalline layer. Critical temperatures (Tc) up to 15.3 K were demonstrated after thermal processing, compared to less than 1 K after deposition. The Tc was always found to be lower on the silicon wafers, by on average 1.9±0.3K for the annealed samples. This difference, as well as a broadening of the superconducting transitions, is nearly independent of the annealing conditions. In situ XRD measurements reveal that the silicide layer becomes strained upon heating due to a mismatch between the thermal expansion of the substrate and that of V3Si. Taking into account the volume reduction due to crystallization, this mismatch is initially larger on sapphire, though stress relaxation allows the silicide layer to be in a relatively unstrained state after cooling. On oxidized silicon, however, no clear evidence of relaxation upon cooling is observed, and V3Si ends up with an out-of-plane strain of 0.3% at room temperature. This strain increases as the sample is cooled down to cryogenic temperatures, though the deformation of the polycrystalline layer is expected to be highly inhomogeneous. Taking into account also the reported occurrence of a Martensitic transition just above the critical temperature, this extrapolated strain distribution is found to closely match an existing model of the strain dependence of A-15 superconducting compounds.
Effect of interfacial spin configuration on y-type spin–orbit torque switching in an antiferromagnetic heavy alloy/ferromagnet bilayer
Authors: Yang Chao-Yao , He Liang-Ching , Yen Yu-Shen , Chen Po-Chuan , Chiu Jih-Chao , Huang San-Ding , Tseng Chih-Hsiang , Lai Chih-Huang
Published: March 2021

This work applied an anisotropic magneto-resistance effect for studying the spin–orbit torque (SOT)-driven magnetization switching in an antiferromagnetic heavy alloy/ferromagnet, PtMn/Co bilayer, under y-type SOT geometry. The tailorable magneto-structural ordering of PtMn provides an additional dimension to study the interplay among SOT efficiency, the interfacial spin configuration, and the y-type SOT switching. The results reveal that the SOT efficiency of PtMn, effective field generated by current, can be enhanced via forming the L10 (antiferromagnetic) phase after annealing; however, the efficiency appears to be less sensitive to the interfacial spin configuration. On the other hand, the critical current for the y-type SOT switching is even strongly associated with the PtMn/Co interfacial spin configuration. The lowest (highest) critical current is yielded when Co is antiferromagnetically (ferromagnetically) coupled to PtMn through the exchange bias. Engineering the interfacial spin configuration may provide an effective strategy to promote the critical current for the SOT device.
3D printing of hollow fiber nanothermites with cavity-mediated self-accelerating combustion
Authors: Zhong Lin , Mao Yaofeng , Zhou Xu , Zheng Dawei , Guo Changping , Wang Ruihao , Zhang Xingquan , Gao Bing , Wang Dunju
Published: March 2021

Advanced techniques, such as 3D printing, have been developed for the design and fabrication of unique structures to meet user-customized requirements. However, the traditional 3D printing technique has not been used for the construction of the nanothermite hollow structure, hindering the development of 3D printing and the further applications of nanothermite materials. Recently, we discovered an unexpected self-accelerating combustion phenomenon of hollow fiber nanothermite (Al/CuO/fluororubber ternary composite). The results show that the stable flame propagation rate of the nanothermite hollow fiber significantly improved compared to the solid fiber from 0.09 to 395 m/s (up to 4400 times higher than the solid fiber), and the combustion test also exhibits the self-accelerating propagation of combustion by the “cavity-mediated effect.” With the versatile shape-design capability, this work on hollow structure nanothermite and developmental potential of 3D printing could lead to structural applications of microrockets, aerospace propulsion components, space exploration, microelectromechanical system (MEMS) devices, and high temperature destruction of MEMS.
STARGATE: A new instrument for high-resolution photodissociation spectroscopy of cold ionic species
Authors: Bejjani Raghed , Roucou Anthony , Urbain Xavier , Moshkunov Konstantin , Vanlancker Guilhem , Lauzin Clément
Published: March 2021

Spectroscopy of transient anions and radicals by gated and accelerated time-of-flight experiment is a new spectrometer developed in UCLouvain. This instrument measures high-resolution photodissociation spectra of mass-selected ions by the combination of a time-of-flight spectrometer including a specific gating, bunching, and re-referencing unit with a nanosecond pulsed dye laser, a pulsed deflection, and an energy selector. The ionic species are generated in a supersonic jet expansion by means of an electric discharge or by the impact of electrons coming from an electron gun. The versatility of the molecular systems that can be addressed by this instrument is illustrated by the presentation of mass spectra of cations, anions, and ionic clusters formed from different gas mixtures and backing pressures. The high-resolution spectrum of the A~2Σ+(002)←X~2Π3/2(000) and A~2Σ+(002)←X~2Π1/2(000) rovibronic bands of N2O+ has been measured and analyzed to provide refined molecular parameters in the A~2Σ+(002) upper state. The A~2Σ+(002)←X~2Π3/2(000) band has been used to evaluate the quality of the experimental setup in terms of rotational temperature, time of measurement for certain signal to noise ratio, and the accuracy of the determination of the wavenumber scale.
Efficacy of the radial pair potential approximation for molecular dynamics simulations of dense plasmas
Authors: Stanek Lucas J. , Clay Raymond C. , Dharma-wardana M. W. C. , Wood Mitchell A. , Beckwith Kristian R. C. , Murillo Michael S.
Published: March 2021

Macroscopic simulations of dense plasmas rely on detailed microscopic information that can be computationally expensive and is difficult to verify experimentally. In this work, we delineate the accuracy boundary between microscale simulation methods by comparing Kohn–Sham density functional theory molecular dynamics (KS-MD) and radial pair potential molecular dynamics (RPP-MD) for a range of elements, temperature, and density. By extracting the optimal RPP from KS-MD data using force matching, we constrain its functional form and dismiss classes of potentials that assume a constant power law for small interparticle distances. Our results show excellent agreement between RPP-MD and KS-MD for multiple metrics of accuracy at temperatures of only a few electron volts. The use of RPPs offers orders of magnitude decrease in computational cost and indicates that three-body potentials are not required beyond temperatures of a few eV. Due to its efficiency, the validated RPP-MD provides an avenue for reducing errors due to finite-size effects that can be on the order of ∼20%.
Reaction mechanism for fluorination reactions with hydroxylated alumina sites: Pathways promoting aluminum combustion
Authors: Tunega Daniel , Pantoya Michelle L. , Nieman Reed , Lischka Hans , Aquino Adelia J. A.
Published: March 2021

Density functional theory calculations were used to reveal the mechanism for the fluorination reaction of active Lewis acid sites on alumina structures, which is important in understanding the pyrophoric processes involving Al particles. In this reaction, hydroxyl groups of active sites are replaced by fluorine anions. Alumina structures were represented by three aluminum aqua hydroxo clusters (labeled AlOOH), in which the Al atom had different coordination spheres, particularly four, five, or six. The F-bearing molecules HF, CH3F, and CF4 were taken as reactants for the fluorination reactions. The overall reaction was represented by four reaction steps as follows: (i) formation of the reaction complex, (ii) activation of the transition state (TS), (iii) deactivation of the TS with a formation of the product complex, and (iv) its decomplexation to individual products. The active reaction center of the TS structure is four-membered, in which two bonds break heterolytically and two form. The lowest reaction barriers were observed for the HF molecule, while the two other molecules had significantly higher reaction barriers. Similarly, the largest overall reaction energies (in absolute value) were found for HF, especially for the five- and six-coordinated Al centers. While the positive charge on the Al center remained almost constant throughout the reaction steps, large charge changes were observed for carbon bearing molecules with a formation of the carbenium cations in the TS step. Realizing the important role of HF in promoting exothermic reactions will enable new molecular design strategies for transforming energy release properties of aluminum powder fuels.
LES of H2-air jet combustion in high enthalpy supersonic crossflow
Authors: Nilsson T. , Zhong S. , Fureby C.
Published: March 2021

Here, we report on large eddy simulation (LES) of supersonic flow, mixing, self-ignition, and combustion in a supersonic hydrogen jet in a crossflow configuration. The configuration has been experimentally investigated at Stanford and consists of a rectilinear channel with a ramp inlet in which a hydrogen jet discharges at a 90° angle to the high enthalpy supersonic crossflow. This configuration has been extensively studied by several research groups and constitutes a good validation case for model development and physics elucidation. The LES model used is based on an unstructured finite volume discretization of the filtered mass, momentum, species, and energy equations and an explicit flow solver. In this study, we investigate the effects of the jet-to-crossflow momentum ratio, the chemical reaction mechanism, and the combustion subgrid model by comparing predictions and by comparing with experimental data including OH* chemiluminescence images and jet penetration data. In general, good agreement is found but with some departures for the smallest reaction mechanisms and some of the LES combustion models. The LES results are also used to elucidate the flow, mixing, and combustion features of this configuration.
Toward 3D data visualization using virtual reality tools
Authors: Kline J. L. , Volegov P. L.
Published: March 2021

Virtual Reality (VR) offers the opportunity to display data, instrumentation, and experimental setups in three dimensions and gives the user the ability to interact with the objects. This technology moves visualization beyond two-dimensional projections on a flat screen with a fixed field of view in which a keyboard or another similar controller is needed to change the view. Advances in both hardware and software for VR make it possible for the non-expert to develop visualization tools for scientific applications both for viewing and for sharing data or diagnostic hardware between users in three dimensions. This manuscript describes application development using two VR software tools, Unity gaming engine and A-frame, for visualizing data and high energy physics targets.
Time-dependent soft and hard x-ray measurements using streak and x-ray diode array diagnostic systems
Authors: Shpilman Z. , Silberstein S. , Rubin D. , Ehrlich Y. , Oysher Z. , Ferber Y. , Levy I.
Published: March 2021

High-temperature, high-density experiments require a simultaneous understanding of temporal and spectral regions. The spectral x-ray streak camera (SXSC) is a new high-temporal-resolution spectral x-ray diagnostic system that allows researchers to differentiate between soft and hard x-ray regions. The diagnostic offers three spectral channels with a wide spectral range, one direct channel that includes a filter and two indirect channels that include both mirrors and filters. The opto-mechanical design positions the filtered radiation at three different locations along the streak photo-cathode (PC) slit to provide time-dependent spectral channels with pico-second temporal resolution. A moderate spatial resolution (150–700 μm) is achieved using slits perpendicular to the PC slit, while the slit width is optimized according to the central channel wavelength (for each channel). The diagnostic system covers a spectral range of 30–500 eV for the mirror channels and >1300 eV for the direct channel. The temporal and spatial axes of the streak camera are calibrated with respect to a sequence of x-ray pulses. The SXSC diagnostic system is tested and analyzed using Marshak-wave emission from an SiO2 foam that was heated by a laser-beam irradiated halfraum. The SXSC results are compared to measurements from an x-ray diode array with similar spectral channels.
Ground state properties and infrared spectra of anharmonic vibrational polaritons of small molecules in cavities
Authors: Fischer Eric W. , Saalfrank Peter
Published: March 2021

Recent experiments and theory suggest that ground state properties and reactivity of molecules can be modified when placed inside a nanoscale cavity, giving rise to strong coupling between vibrational modes and the quantized cavity field. This is commonly thought to be caused either by a cavity-distorted Born–Oppenheimer ground state potential or by the formation of light–matter hybrid states, vibrational polaritons. Here, we systematically study the effect of a cavity on ground state properties and infrared spectra of single molecules, considering vibration-cavity coupling strengths from zero up to the vibrational ultrastrong coupling regime. Using single-mode models for Li–H and O–H stretch modes and for the NH3 inversion mode, respectively, a single cavity mode in resonance with vibrational transitions is coupled to position-dependent molecular dipole functions. We address the influence of the cavity mode on polariton ground state energies, equilibrium bond lengths, dissociation energies, activation energies for isomerization, and on vibro-polaritonic infrared spectra. In agreement with earlier work, we observe all mentioned properties being strongly affected by the cavity, but only if the dipole self-energy contribution in the interaction Hamiltonian is neglected. When this term is included, these properties do not depend significantly on the coupling anymore. Vibro-polaritonic infrared spectra, in contrast, are always affected by the cavity mode due to the formation of excited vibrational polaritons. It is argued that the quantized nature of vibrational polaritons is key to not only interpreting molecular spectra in cavities but also understanding the experimentally observed modification of molecular reactivity in cavities.
Space–charge limited current in nanodiodes: Ballistic, collisional, and dynamical effects
Authors: Zhang Peng , Ang Yee Sin , Garner Allen L. , Valfells Ágúst , Luginsland J. W. , Ang L. K.
Published: March 2021

This Perspective reviews the fundamental physics of space–charge interactions that are important in various media: vacuum gap, air gap, liquids, and solids including quantum materials. It outlines the critical and recent developments since a previous review paper on diode physics [Zhang et al. Appl. Phys. Rev. 4, 011304 (2017)] with particular emphasis on various theoretical aspects of the space–charge limited current (SCLC) model: physics at the nano-scale, time-dependent, and transient behaviors; higher-dimensional models; and transitions between electron emission mechanisms and material properties. While many studies focus on steady-state SCLC, the increasing importance of fast-rise time electric pulses, high frequency microwave and terahertz sources, and ultrafast lasers has motivated theoretical investigations in time-dependent SCLC. We particularly focus on recent studies in discrete particle effects, temporal phenomena, time-dependent photoemission to SCLC, and AC beam loading. Due to the reduction in the physical size and complicated geometries, we report recent studies in multi-dimensional SCLC, including finite particle effects, protrusive SCLC, novel techniques for exotic geometries, and fractional models. Due to the importance of using SCLC models in determining the mobility of organic materials, this paper shows the transition of the SCLC model between classical bulk solids and recent two-dimensional (2D) Dirac materials. Next, we describe some selected applications of SCLC in nanodiodes, including nanoscale vacuum-channel transistors, microplasma transistors, thermionic energy converters, and multipactor. Finally, we conclude by highlighting future directions in theoretical modeling and applications of SCLC.
Electronegative microchannel guided streamer propagation for in-liquid spark breakdown applications
Authors: Ham Hwi-Chan , Yoh Jack. J.
Published: March 2021

One of the well-known challenging issues of in-liquid spark breakdown is electrode wear and wear-dependent deposit energy fluctuation, regardless of the electrode materials. This work suggests a method that can reduce the breakdown threshold by an order of magnitude and hence enhances the likelihood of breakdown, regardless of wear. Generally, the negative streamer propagates in a branching way; however, the present experiment indicates that the electronegative microchannel is converged with the streamer propagation and extends the breakdown gap distance between the electrodes. Subsequently, the breakdown-possible gap distance was extended by 14.3 times, leading to an enhancement of shockwave intensity by 33%. Such an extension of the breakdown conditions was achievable without any additional source energy input or changing the substance of dielectric electrodes. Thus, the results provide a favorable scheme for energy reduction in high-voltage systems, cost saving for electrode replacement, and enhancement of the propagating shock pressure.
Effect of artery curvature on the coronary fractional flow reserve
Authors: Freidoonimehr Navid , Arjomandi Maziar , Zander Anthony , Chin Rey
Published: March 2021

Understanding the effect of the artery curvature on the pressure drop inside the arteries is of great importance due to the existence of several curved portions inside the coronary arterial system. In this paper, an experimental model is developed to account for the effect of the curvature of the coronary arteries on the pressure drop and Fractional Flow Reserve (FFR). FFR is an index for the evaluation of the functional significance of coronary stenosis and is defined as the ratio of the coronary pressure downstream of the stenosis to its upstream value. To measure the pressure drop and FFR across curved artery models, three-dimensional-printed curved artery models are fabricated and installed in the test section of the experimental rig. For ratios of curvature radius over the artery diameter ranging from 2 to 7, there are a minimum value for the pressure drop and, hence, a corresponding maximum value for FFR at a ratio of approximately 3. For the curved arteries with larger curvature radii, the pressure drop increases, and consequently, FFR decreases with an increase in the radius. The results showed that an accurate evaluation of the pressure drop and FFR inside a curved coronary artery can only be achieved by accounting for the effect of curvature parameters including the curvature angle and radius, such that neglecting the effect of the artery curvature results in an underestimation of the pressure drop by about 25%–35%. The developed equation is able to determine the pressure drop inside a curved coronary artery model noninvasively.
A transmitted-beam diagnostic for the wavelength-tunable UV drive beam on OMEGA
Authors: Katz J. , Turnbull D. , Kruschwitz B. E. , Rigatti A. L. , Rinefierd R. , Froula D. H.
Published: March 2021

A transmitted-beam diagnostic (P9TBD) was developed as part of a new experimental platform used to study laser–plasma interactions on OMEGA. Located in the opposing port to the wavelength-tunable (350 nm to 353 nm) UV drive beam, the P9TBD characterizes the beam after it propagates through an undersense plasma. The instrument consists of a large-aperture window that allows light to exit the target chamber and project onto a thin sheet of semi-transparent diffuser material. Light transmitted through the diffuser is recorded using a time-integrated camera and a fiber-optically coupled streaked spectrometer, providing measurements of the energy, power, fluence, polarization, and spectrum of the transmitted beam. The diagnostic enables direct observation of a variety of cross-beam energy transfer phenomena, such as wavelength detuning, polarization effects, and gain saturation.
Reconstructing 3D asymmetries in laser-direct-drive implosions on OMEGA
Authors: Mannion O. M. , Woo K. M. , Crilly A. J. , Forrest C. J. , Frenje J. A. , Johnson M. Gatu , Glebov V. Yu. , Knauer J. P. , Mohamed Z. L. , Romanofsky M. H. , Stoeckl C. , Theobald W. , Regan S. P.
Published: March 2021

Three-dimensional reconstruction algorithms have been developed, which determine the hot-spot velocity, hot-spot apparent ion temperature distribution, and fuel areal-density distribution present in laser-direct-drive inertial confinement fusion implosions on the OMEGA laser. These reconstructions rely on multiple independent measurements of the neutron energy spectrum emitted from the fusing plasma. Measurements of the neutron energy spectrum on OMEGA are made using a suite of quasi-orthogonal neutron time-of-flight detectors and a magnetic recoil spectrometer. These spectrometers are positioned strategically around the OMEGA target chamber to provide unique 3D measurements of the conditions of the fusing hot spot and compressed fuel near peak compression. The uncertainties involved in these 3D reconstructions are discussed and are used to identify a new nTOF diagnostic line of sight, which when built will reduce the uncertainty in the hot-spot apparent ion temperature distribution from 700 to <400 eV.
Transient 2D IR spectroscopy from micro- to milliseconds
Authors: Hamm Peter
Published: March 2021

A new application of high-repetition rate, femtosecond Yb-laser/amplifier systems is introduced: transient 2D IR spectroscopy covering the time range from micro- to milliseconds. This approach intertwines the measurement of 2D IR spectra with the time separation from an actinic pump pulse and utilizes the high repetition rate of these lasers systems in two ways: by offering a high time resolution (10 µs) and by enabling the measurement of many 2D IR spectra. The well-studied photocycle of bacteriorhodopsin is used as a demonstration object in this proof-of-principle experiment.
Noninvasive neuromagnetic single-trial analysis of human neocortical population spikes
Authors: Waterstraat Gunnar , Körber Rainer , Storm Jan-Hendrik , Curio Gabriel
Published: March 2021

Significance

Evolution has shaped the human brain as a “single-trial” processor reacting fast and reliably to environmental threats. The noninvasive analysis of its electrical activity commonly draws on electroencephalography/magnetoencephalography (EEG/MEG) with a millisecond time resolution suitable even for short-lived neuronal output spikes. However, while standard EEG/MEG can detect very small evoked population spikes, it does so only after averaging over hundreds of trials. Here, MEG based on an ultralow-noise superconducting quantum interference device (SQUID) is shown to enable the first noninvasive single-trial characterization of human cortical population spikes, revealing amplitudes highly variable between trials and intertrial correlated response latencies. Thus, by expanding the scope of noninvasive neurotechnology, ultralow-noise MEG can support single-trial analyses of input–output characteristics in the human brain.
Limitation of phosphate assimilation maintains cytoplasmic magnesium homeostasis
Authors: Bruna Roberto E. , Kendra Christopher G. , Groisman Eduardo A. , Pontes Mauricio H.
Published: March 2021

Significance

Phosphorus (P) is essential for life. As the fifth-most-abundant element in living cells, P is required for the synthesis of an array of biological molecules including (d)NTPs, nucleic acids, and membranes. Organisms typically acquire environmental P as inorganic phosphate (Pi). While essential for growth and viability, excess intracellular Pi is toxic for both bacteria and eukaryotes. Using the bacterium
Salmonella enterica
serovar Typhimurium as a model, we establish that Pi cytotoxicity is manifested following its assimilation into adenosine triphosphate (ATP), which acts as a chelating agent for Mg
2+
and other cations. Our findings identify physiological processes disrupted by excessive Pi and how bacteria tune P assimilation to cytoplasmic Mg
2+
levels.
Super-resolution mapping of cellular double-strand break resection complexes during homologous recombination
Authors: Whelan Donna R. , Rothenberg Eli
Published: March 2021

Significance

DNA resection is an initial, decisive step in the homologous recombination repair pathway of DNA double-strand breaks (DSBs). However, the individual roles and cross-talk of key proteins in this process remain unclear. To resolve the spatiotemporal dynamics of this intricate process, we applied multicolor single-molecule localization microscopy along with robust analytical approaches. Our data reveal the dynamic actions and interactions of MRE11, BRCA1, and CtIP both as a multimer and individually; the recruitment and spatial exclusion of 53BP1; the role of BLM helicase alongside EXO1 and DNA2 nucleases; and the inhibitory mechanisms of MRE11 exo-/endonuclease inhibition. Together, our findings describe important aspects of DNA DSB repair and highlight key differences between repair of clustered damage and sporadic endogenous breaks.
Role of intramolecular hydrogen bonds in promoting electron flow through amino acid and oligopeptide conjugates
Authors: Orłowski Rafał , Clark John A. , Derr James B. , Espinoza Eli M. , Mayther Maximilian F. , Staszewska-Krajewska Olga , Winkler Jay R. , Jędrzejewska Hanna , Szumna Agnieszka , Gray Harry B. , Vullev Valentine I. , Gryko Daniel T.
Published: March 2021

Significance

Long-range electron transfer pervades biology, chemistry, and engineering, as it is critical for life-sustaining processes, chemical transformations, energy conversion, as well as electronic and photonic technologies. Elucidating the factors that control the rates of long-range electron transfer remains an outstanding challenge, owing in part to the complexity of proteins and other macromolecular structures that mediate such processes. We have found that short peptides linking electron donors and acceptors can assume folds with intramolecular hydrogen bond interactions that provide electronic-coupling pathways for ultrafast charge transfer. Our work will assist designs of donor–acceptor systems for efficient energy conversion and storage.
Transnational coalition building: The case of volunteers in the conflict in Abkhazia
Authors: Kvakhadze Aleksandre
Published: March 2021

The 1992–93 war in Abkhazia was one of several ethno-nationalist conflicts which blighted the Caucasus, following the demise of the Soviet Union. The conflict involved the large-scale mobilization of volunteers, from southern Russia and from further afield, who allied with Abkhaz secessionists in the build-up to, and during, the war. This paper examines the coalition-building process between Abkhaz secessionists and other ethno-nationalist movements throughout the conflict. This article’s central questions examine how the coalitions between Abkhaz and nonindigenous movements formed and how the process of coalitionbuilding impacted on the longevity of such alliances. Drawing on the concept of transnational activism, it analyses the role of ethnic relatedness, political opportunity and common threat as contributing factors which influenced mobilization and the alliance-building process. The paper assesses the durability of the transnational coalitions in three different phases of the Georgian- Abkhaz conflict. The study illustrates that the most durable alliances formed with Abkhaz’s closest ethnic relatives Abkhaz- Abaza movements, Ossetian nationalists and the broader “Russian world.” It demonstrates that the Abkhaz connection with Chechen and Circassian movements was event-based and temporary.
Impact of support material deformation in MEMS bulk micromachined diaphragm pressure sensors
Authors: Brace Eric , Ghaderian Sepideh , Ghannoum AbdulRahman , Nieva Patricia
Published: March 2021

In this work, experimental data and finite element analysis reveals deflection in diaphragm supporting material leading to non-linear pressure-reflection response. These results are contrary to the standard assumptions presented in literature, where modelling of deflection response in diaphragm pressure sensors is primarily carried out assuming a rigid supporting structure. An extrinsic fiber-optic Fabry–Perot pressure sensor, based on micro-electromechanical system, is developed and used to investigate optical deflection response. While the sensor is not novel, a series of experiments to validate support deflection phenomena are designed and carried out using a silicon membrane at gauge pressures from 0 to 1000 PSI in ambient temperature. The device is packaged with an industry standard stainless-steel housing typically used in plastic injection moulding. Sensor performance is compared to analytical and finite element modelling. Results suggest that the device is experiencing greater deflection than analytically predicted at pressures above 200 PSI, where a rigid support is assumed in existing literature. Based on these results, a modified analytical model is proposed to correct for this behaviour. The modified model is created through addition of a nonlinear component to an existing model, which is then fitted to the experimental data using least-square methods. Prediction of the experimental deflection results is improved from 81% error using a fixed-support analytical model to 4% error using the presented adjusted model. It is demonstrated that nonlinear effects are present and optically measurable in cases where deflection is lower than 1% of the membrane thickness. This work will aid in the implementation of high-resolution pressure sensors operating in harsh environment conditions.
The Fourier signatures of memristive hysteresis
Authors: Pershin Yuriy V , Chien Chih-Chun , Di Ventra Massimiliano
Published: March 2021

While resistors with memory, sometimes called memristive elements (such as ReRAM cells), are often studied under conditions of periodic driving, little attention has been paid to the Fourier features of their memory response (hysteresis). Here we demonstrate experimentally that the hysteresis of memristive systems can be unambiguously distinguished from the linear or non-linear response of systems without hysteresis by the values of certain Fourier series coefficients. We also show that the Fourier series convergence depends on driving conditions, and introduce a measure of hysteresis. These results may be used to quantify the memory content of resistive memories, and tune their Fourier spectrum according to the excitation signal.
An antisymmetric neural network to predict free energy changes in protein variants
Authors: Benevenuta S , Pancotti C , Fariselli P , Birolo G , Sanavia T
Published: March 2021

The prediction of free energy changes upon protein residue variations is an important application in biophysics and biomedicine. Several methods have been developed to address this problem so far, including physical-based and machine learning models. However, most of the current computational tools, especially data-driven approaches, fail to incorporate the antisymmetric basic thermodynamic principle: a variation from wild-type to a mutated form of the protein structure (

X

W

→

X

M

) and its reverse process (

X

M

→

X

W

) must have opposite values of the free energy difference:

Δ
Δ

G

W
M

=
−
Δ
Δ

G

M
W

. Here, we build a deep neural network system that, by construction, satisfies the antisymmetric properties. We show that the new method (ACDC-NN) achieved comparable or better performance with respect to other state-of-the-art approaches on both direct and reverse variations, making this method suitable for scoring new protein variants preserving the antisymmetry. The code is available at: https://github.com/compbiomed-unito/acdc-nn.
Thermal oxidation of Ru(0001) to RuO2(110) studied with ambient pressure x-ray photoelectron spectroscopy
Authors: Diulus J Trey , Tobler Benjamin , Osterwalder Jürg , Novotny Zbynek
Published: March 2021

The thermal oxidation of Ru(0001) has been extensively studied in the surface science community to determine the oxidation pathway towards ruthenium dioxide (RuO2(110)), improving the knowledge of Ru(0001) surface chemistry. Using time-lapsed ambient-pressure x-ray photoelectron spectroscopy (APXPS), we investigate the thermal oxidation of single-crystalline Ru(0001) films toward rutile RuO2(110) in situ. APXPS spectra were continuously collected while the Ru(0001) films were exposed to a fixed O2 partial pressure of 10−2 mbar and the sample temperature was increased stepwise from room temperature to 400 °C. We initially observe the removal of adventitious carbon and subsequent formation of a chemisorbed oxygen overlayer at 250 °C. Further annealing to 300 °C leads to an increase in thickness of the oxide layer and a shift in the Ru–O component of the Ru 3d spectra, indicating the presence of a metastable O–Ru–O trilayer structure. A rapid formation of the RuO2 rutile phase with an approximate thickness of at least 2.6 nm is formed about four minutes after stabilizing the temperature at 350 °C and subsequent annealing to 400 °C, signaled by a distinct binding energy shift in both the Ru 3d and O 1s spectra, as well as quantitative analysis of XPS intensities. This observed autocatalytic oxidation process agrees well with previous theoretical models and experimental studies, and the data provide the unambiguous spectral identification of one proposed metastable precursor required for full oxidation to rutile RuO2(110). Further ex situ characterization of the grown oxide with x-ray photoelectron diffraction confirms the presence of three rotated domains of rutile RuO2(110) and reveals their orientation relative to the substrate lattice.
Multiple magnetic states of CoPc molecule on a two-dimensional layer of NbSe2
Authors: Montero Ana M , Guimarães Filipe S M , Lounis Samir
Published: March 2021

Molecular spintronics hinges on the detailed understanding of electronic and magnetic properties of molecules interfaced with various materials. Here we demonstrate with ab initio simulations that the prototypical Co-phthalocyanine (CoPc) molecule can surprisingly develop multi-spin states once deposited on the two-dimensional 2H–NbSe2 layer. Conventional calculations based on density functional theory (DFT) show the existence of low, regular and high spin states, which reduce to regular and high spins states once correlations are incorporated with a DFT + U approach. Depending on U, the ground state is either the low spin or high spin state with energy differences affected by the molecular orientation on top of the substrate. Our results are compared to recent scanning probe measurements and motivate further theoretical and experimental studies on the unveiled rich multi-magnetic behavior of CoPc molecule.