bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic transport mechanisms in a thin crystal of the Kitaev candidate
α
-RuCl3 probed through guarded high impedance measurements
Authors: Barfield Patrick , Tran Vinh , Nagarajan Vikram , Martinez Maya , Diego Amirari , Bergner Derek , Lanzara Alessandra , Analytis James G. , Ojeda-Aristizabal Claudia
Published: June 2023

α-RuCl3 is considered to be the top candidate material for the experimental realization of the celebrated Kitaev model, where ground states are quantum spin liquids with interesting fractionalized excitations. It is, however, known that additional interactions beyond the Kitaev model trigger in α-RuCl3 a long-range zigzag antiferromagnetic ground state. In this work, we investigate a nanoflake of α-RuCl3 through guarded high impedance measurements aimed at reaching the regime where the system turns into a zigzag antiferromagnet. We investigated a variety of temperatures (1.45–175 K) and out-of-plane magnetic fields (up to 11 T), finding a clear signature of a structural phase transition at ≈160 K as reported for thin crystals of α-RuCl3, as well as a thermally activated behavior at temperatures above ≈30 K, with a characteristic activation energy significantly smaller than the energy gap that we observe for α-RuCl3 bulk crystals through our angle resolved photoemission spectroscopy (ARPES) experiments. Additionally, we found that below ≈30 K, transport is ruled by Efros–Shklovskii variable range hopping (VRH). Most importantly, our data show that below the magnetic ordering transition known for bulk α-RuCl3 in the frame of the Kitaev–Heisenberg model (≈7 K), there is a clear deviation from VRH or thermal activation transport mechanisms. Our work demonstrates the possibility of reaching, through specialized high impedance measurements, the thrilling ground states predicted for α-RuCl3 at low temperatures in the frame of the Kitaev–Heisenberg model and informs about the transport mechanisms in this material in a wide temperature range.
Magnetic field imaging by hBN quantum sensor nanoarray
Authors: Sasaki Kento , Nakamura Yuki , Gu Hao , Tsukamoto Moeta , Nakaharai Shu , Iwasaki Takuya , Watanabe Kenji , Taniguchi Takashi , Ogawa Shinichi , Morita Yukinori , Kobayashi Kensuke
Published: June 2023

Placing a sensor close to the target at the nano-level is a central challenge in quantum sensing. We demonstrate magnetic field imaging with a boron vacancy (VB−) defects array in hexagonal boron nitride with a few 10 nm thickness. VB− sensor spots with a size of (100 nm)2 are arranged periodically with nanoscale accuracy using a helium ion microscope and attached tightly to a gold wire. The sensor array allows us to visualize the magnetic field induced by the current in the straight micro wire with a high spatial resolution. Each sensor exhibits a practical sensitivity of 73.6 μT/Hz0.5, suitable for quantum materials research. Our technique of arranging VB− quantum sensors periodically and tightly on measurement targets will maximize their potential.
Global sensitivity analysis for phosphate slurry flow in pipelines using generalized polynomial chaos
Authors: Elkarii M. , Boukharfane R. , Benjelloun S. , Bouallou C. , El Moçayd N.
Published: June 2023

Slurry transportation via pipelines has garnered growing attention across various industries worldwide, thanks to its efficiency and environmental friendliness. It has emerged as a vital tool for conveying significant volumes of raw phosphate material from extraction points to industrial plants, where it is processed into fertilizers. Yet, optimal and secure pipeline operations necessitate the careful calibration of several physical parameters and their interplay to minimize energy losses. A thorough exploration of the flow pressure drop and the various factors that influence it constitutes a crucial step in attaining this goal. The computational fluid dynamics techniques required to simulate three-dimensional slurry pipe flows pose formidable challenges, primarily due to their high computational costs. Furthermore, numerical solutions for slurry flows are frequently subject to uncertainties arising from the initial and boundary conditions in the mathematical models employed. In this study, we propose the use of polynomial chaos expansions to estimate the uncertainty inherent in the desired slurry flow and perform a sensitivity analysis of flow energy efficiency. In this framework, five parameters are considered as random variables with a given probability distribution over a prescribed range of investigation. The uncertainty is then propagated through the two-phase flow model to statistically quantify their effect on the results. Our findings reveal that variations in slurry velocity and particle size play a pivotal role in determining energy efficiency. Therefore, controlling these factors represents a critical step in ensuring the efficient and safe transportation of slurry through pipelines.
Electrode area dependent switching behavior of Ge2Sb2Se4Te1 phase change material driven by narrow voltage pulse
Authors: Yuan Wei , Lu Yilei , Lu Liangjun , Wang Rui , Weng Yuyan , You Lu , Fang Liang , Zhou Linjie , Zheng Fengang
Published: June 2023

As a recently studied phase change material, Ge2Sb2Se4Te1 (GSST) shows excellent potential in the application of optical devices, because it presents very low loss in the amorphous state within the optical communication wavelength of 1550 nm and exhibits significant differences in optical properties before and after phase change. However, it is still challenging that, in real GSST devices, phase change switching is driven by narrow voltage pulse. In this study, the sandwich structures of GSST film with different electrode areas were prepared to analyze the phase change switching performance between crystalline and amorphous states. The results show that the endurance cycling of phase change switching increases with decreasing electrode area. When the electrode radius is 1 μm, the phase change switching number can reach 10 000. The improvement of this phase change switching can be attributed to the temperature uniformity, which was verified by the simulation of electrical pulse heating.
Time-stretched multi-hit 3D velocity map imaging of photoelectrons
Authors: Goudreau E. Scott , Boguslavskiy Andrey E. , Moffatt Douglas J. , Makhija Varun , Hemsworth Michael , Lausten Rune , Marceau Claude , Wilkinson Iain , Stolow Albert
Published: June 2023

The 2D photoelectron velocity map imaging (VMI) technique is commonly employed in gas-phase molecular spectroscopy and dynamics investigations due to its ability to efficiently extract photoelectron spectra and angular distributions in a single experiment. However, the standard technique is limited to specific light-source polarization geometries. This has led to significant interest in the development of 3D VMI techniques, which are capable of measuring individual electron positions and arrival times, obtaining the full 3D distribution without the need for inversion, forward-convolution, or tomographic reconstruction approaches. Here, we present and demonstrate a novel time-stretched, 13-lens 3D VMI photoelectron spectrometer, which has sub-camera-pixel spatial resolution and 210 ps (σ) time-of-flight (TOF) resolution (currently limited by trigger jitter). We employ a kHz CMOS camera to image a standard 40 mm diameter microchannel plate (MCP)/phosphor anode detector (providing x and y positions), combined with a digitizer pick-off from the MCP anode to obtain the electron TOF. We present a detailed analysis of time-space correlation under data acquisition conditions which generate multiple electrons per laser shot, and demonstrate a major advantage of this time-stretched 3D VMI approach: that the greater spread in electron TOFs permits for an accurate time- and position-stamping of up to six electrons per laser shot at a 1 kHz repetition rate.
How microplastics are transported and deposited in realistic upper airways?
Authors: Islam Mohammad S. , Rahman Md. Mizanur , Larpruenrudee Puchanee , Arsalanloo Akbar , Beni Hamidreza Mortazavy , Islam Md. Ariful , Gu YuanTong , Sauret Emilie
Published: June 2023

Microplastics are tiny plastic debris in the environment from industrial processes, various consumer items, and the breakdown of industrial waste. Recently, microplastics have been found for the first time in the airways, which increases the concern about long-term exposure and corresponding impacts on respiratory health. To date, a precise understanding of the microplastic transport to the airways is missing in the literature. Therefore, this first-ever study aims to analyze the microplastic transport and deposition within the upper lung airways. A computational fluid dynamics-discrete phase model approach is used to analyze the fluid flow and microplastic transport in airways. The sphericity concept and shape factor values are used to define the non-spherical microplastics. An accurate mesh test is performed for the computational mesh. The numerical results report that the highly asymmetric and complex morphology of the upper airway influences the flow fields and microplastic motion along with the flow rate and microplastic shape. The nasal cavity, mouth-throat, and trachea have high pressure, while a high flow velocity is observed at the area after passing the trachea. The flow rates, shape, and size of microplastics influence the overall deposition pattern. A higher flow rate leads to a lower deposition efficiency for all microplastic shapes. The nasal cavity has a high deposition rate compared to other regions. The microplastic deposition hot spot is calculated for shape and size-specific microplastic at various flow conditions. The findings of this study and more case-specific analysis will improve the knowledge of microplastic transport in airways and benefit future therapeutics development. The future study will be focused on the effect of various microplastic shapes on the human lung airways under the healthy and diseased airways conditions.
Inverse designed photonic crystals for spatial filtering
Authors: Babayigit Ceren , Grineviciute Lina , Nikitina Julianija , Melnikas Simas , Gailevicius Darius , Staliunas Kestutis
Published: June 2023

Zero incidence angle spatial filters of a compact design can be very useful, among others, for intracavity spatial filtering in high-power micro-lasers. Typically, micro-lasers, especially in high-power operation regimes, emit beams of low spatial quality due to the large aspect ratio of the laser resonator. A promising proposal for compact spatial filtering is the integration of the Photonic Crystals structures into the micro-resonator of the laser. Here, we report efficient spatial filters with desired filtering properties engineered by the inverse design. Such filters can be designed not only separately for both polarizations of the incident radiation but also simultaneously for both S and P polarizations. Moreover, we fabricate the inverse-designed structure by physical vapor deposition and highlight good correspondence of the angle-wavelength transmission map to the target one.
Quantum computing and materials science: A practical guide to applying quantum annealing to the configurational analysis of materials
Authors: Camino B. , Buckeridge J. , Warburton P. A. , Kendon V. , Woodley S. M.
Published: June 2023

Using quantum computers for computational chemistry and materials science will enable us to tackle problems that are intractable on classical computers. In this paper, we show how the relative energy of defective graphene structures can be calculated by using a quantum annealer. This simple system is used to guide the reader through the steps needed to translate a chemical structure (a set of atoms) and energy model to a representation that can be implemented on quantum annealers (a set of qubits). We discuss in detail how different energy contributions can be included in the model and what their effect is on the final result. The code used to run the simulation on D-Wave quantum annealers is made available as a Jupyter Notebook. This Tutorial was designed to be a quick-start guide for the computational chemists interested in running their first quantum annealing simulations. The methodology outlined in this paper represents the foundation for simulating more complex systems, such as solid solutions and disordered systems.
Structural effects on the performance of microfabricated in-plane
π
-type thermoelectric devices composed of p-type Mg2Sn0.8Ge0.2 and n-type Bi layers
Authors: Ohkubo Isao , Murata Masayuki , Ohi Akihiko , Lima Mariana S. L. , Sakurai Takeaki , Aizawa Takashi , Mori Takao
Published: June 2023

Miniaturized in-plane π-type thermoelectric devices composed of p-type Mg2Sn0.8Ge0.2 and n-type Bi layers were prepared by microfabrication techniques. Structural effects on thermoelectric device performance need to be evaluated and optimized to improve device performance and operation. In this study, a rational analysis of the correction of the open-circuit output voltages, output powers, and output power densities by using effective temperature differences was performed, and the effects of device geometries (e.g., the number of π junctions and the cross-sectional area ratio between p- and n-type layers) were determined by comparing different types of in-plane π-type thermoelectric devices. The results revealed that it is crucial to consider the heat transfer loss caused by thermal contact effects in the device and to optimize the structural geometries of the device. Proper structural trends and the effects of the number of p–n pairs on the device performance were observed, which indicated the reasonable device operation of microfabricated in-plane π-type thermoelectric devices.
A laboratory-based multifunctional near ambient pressure X-ray photoelectron spectroscopy system for electrochemical, catalytic, and cryogenic studies
Authors: Haug Leander , Griesser Christoph , Thurner Christoph W. , Winkler Daniel , Moser Toni , Thaler Marco , Bartl Pit , Rainer Manuel , Portenkirchner Engelbert , Schumacher David , Dierschke Karsten , Köpfle Norbert , Penner Simon , Beyer Martin K. , Loerting Thomas , Kunze-Liebhäuser Julia , Klötzer Bernhard
Published: June 2023

A versatile multifunctional laboratory-based near ambient pressure x-ray photoelectron spectroscopy (XPS) instrument is presented. The entire device is highly customized regarding geometry, exchangeable manipulators and sample stages for liquid- and solid-state electrochemistry, cryochemistry, and heterogeneous catalysis. It therefore delivers novel and unique access to a variety of experimental approaches toward a broad choice of functional materials and their specific surface processes. The high-temperature (electro)catalysis manipulator is designed for probing solid state/gas phase interactions for heterogeneous catalysts including solid electrolyzer/fuel cell electrocatalysts at pressures up to 15 mbar and temperatures from room temperature to 1000 °C. The liquid electrochemistry manipulator is specifically designed for in situ spectroscopic investigations of polarized solid/liquid interfaces using aqueous electrolytes and the third one for experiments for ice and ice-like materials at cryogenic temperatures to approximately −190 °C. The flexible and modular combination of these setups provides the opportunity to address a broad spectrum of in situ and operando XPS experiments on a laboratory-based system, circumventing the limited accessibility of experiments at synchrotron facilities.
Comparison and modification of turbulence models for active flow separation control over a flat surface
Authors: Pour Razaghi Mohammad Javad , Rezaei Sani Seyed Mojtaba , Masoumi Yasin
Published: June 2023

The present work studied various models for predicting turbulence in the problem of injecting a fluid microjet into the boundary layer of a turbulent flow. For this purpose, the one-equation Spalart–Allmaras (SA), two-equation k–ε and k–ω, multi-equation transition k-kL–ω, transition shear stress transport (SST), and Reynolds stress models were used for solving the steady microjet into the turbulent boundary layer, and their results are compared with experimental results. Comparing the results indicated that the steady solution methods performed sufficiently we for this problem. Furthermore, it was found that the four-equation transition SST model was the most accurate method for predicting turbulence in this problem. This model predicted the velocity along the x-axis in near- and far-jet locations with about 1% and 5% average errors, respectively. It also outperformed the other methods in predicting Reynolds stresses, especially at the center (nearly 5% error). Moreover, the modified four-equation transition SST model has improved the system's performance in predicting the studied parameters by utilizing Sørensen correlations in predicting Reθt (the transition momentum thickness Reynolds number), Flength (an empirical correlation that controls the length of the transition region), and Reθc (the critical Reynolds number where the intermittency first starts to increase in the boundary layer).
Nonreciprocal photonic quantum router via synthetic magnetism
Authors: Ren Ya-Long , Ma Sheng-Li , Xie Ji-Kun , Li Fu-Li
Published: June 2023

Nonreciprocal photon transmissions at the single-quantum level play crucial roles in optical information processing. Here, we propose to develop a nonreciprocal photonic quantum router via synthetic magnetism, which can route photons of an input quantum state in one direction but block them in the other direction. Our model is based on a superconducting circuit of linearly coupled microwave cavities, and the Lorentz reciprocity is broken by synthesizing an effective magnetic field for photons. As a result, an input quantum signal from a given direction can be delivered on-demand to either of the two output ports, but it from the opposite direction is completely absorbed. Our scheme does not involve strong static magnetic fields and optical nonlinearity for generating the desired optical nonreciprocity. It is, therefore, expected to be a key ingredient for the construction of on-chip quantum networks.
Bipolar thermoelectricity in S/I/NS and S/I/SN superconducting tunnel junctions
Authors: Hijano A. , Bergeret F. S. , Giazotto F. , Braggio A.
Published: June 2023

Recent studies have shown the potential for bipolar thermoelectricity in superconducting tunnel junctions with asymmetric energy gaps. The thermoelectric performance of these systems is significantly impacted by the inverse proximity effects present in the normal-superconducting bilayer, which is utilized to adjust the gap asymmetry in the junction. Here, we identify the most effective bilayer configurations, and we find that directly tunnel-coupling the normal metal side of the cold bilayer with the hot superconductor is more advantageous compared to the scheme used in experiments. By utilizing quasiclassical equations, we examined the nonlinear thermoelectric junction performance as a function of the normal metal film thickness and the quality of the normal-superconducting interface within the bilayer, thereby determining the optimal design to observe and maximize this nonequilibrium effect. Our results offer a roadmap to achieve improved thermoelectric performance in superconducting tunnel junctions, with promising implications for a number of applications.
Effects of various backward-facing steps on flow characteristics and sediment behaviors
Authors: Nguyen Van Thinh
Published: June 2023

The study of flow over various steps behind the hydraulic structures, such as weirs, dams, spillways, barrages, and flood gates, is still of particular interest to researchers due to the complexity of flow characteristics and sediment behaviors at near-bed region. This study investigates the effect of various inclined backward-facing step (BFS) angles on near-bed turbulent flow structures and bedload transport rate in surface jet flow regime. A combined numerical technique of large eddy simulation and discrete element method, based on the open sources package OpenFOAM, is employed. The validation of the numerical model shows a good agreement between the simulation results and observed data obtained from different experiments. The simulation results reveal that the flow does not form a separation zone when the BFS angle is less than 20°, wherein the near-bed turbulence intensity is insufficient to induce substantial sediment movements. As the step angle is increased to a certain value (20°), the separation flow is formed. Consequently, the near-bed turbulence intensity is significantly increased due to the splat effect, and the sediment flux is also drastically increased. As the BFS angle further increases to 30° and 90°, the reattachment length is extended without notable changes in maximum turbulence intensity near the bed. The peaks of the mean bedload transport rate are located further downstream along the extended reattachment length. The quadrant analysis for bedload transport is performed to quantify the interactions between the flow and sediment movement. The results demonstrate that the sweep event plays significant role in moving most sediment to downstream of the reattachment point. On the other hand, right upstream of the reattachment point, the burst becomes the dominant turbulence event to move the majority of the sediment backward in the upstream direction.
Unintentional p-type conductivity in intrinsic Ge-rich SiGe/Ge heterostructures grown on Si(001)
Authors: Tetzner H. , Seifert W. , Skibitzki O. , Yamamoto Y. , Lisker M. , Mirza M. M. , Fischer I. A. , Paul D. J. , De Seta Monica , Capellini G.
Published: June 2023

In this work, we investigate the effective background charge density in intrinsic Si0.06Ge0.94/Ge plastically relaxed heterostructures deposited on Si(001). Hall effect measurements and capacitance–voltage profiling reveal a p-type conductivity in the nominally intrinsic layer with a hole concentration in the mid 1015 cm−3 range at temperatures between 50 and 200 K. In view of the carrier freeze out that we observe below 50 K, we attribute the origin of these carriers to the ionization of shallow acceptor-like defect states above the valence band. In addition, one dominant hole trap located at mid-gap position is found by deep level transient spectroscopy. Carrier trapping kinetics measurements can be interpreted as due to a combination of point defects, likely trapped in the strain field of extended defects, i.e., the threading dislocation.
Ising superconductivity: A first-principles perspective
Authors: Wickramaratne Darshana , Mazin I. I.
Published: June 2023

The recent discovery of Ising superconductivity has garnered much interest due in part to the resilience of these superconductors to large in-plane magnetic fields. In this Perspective, we explain the basic concepts that define the behavior of Ising superconductors, provide an overview of the electronic structure and magnetic properties with a focus on NbSe2, summarize key experimental observations that have been made in this class of superconductors, highlight the role that defects and proximity-induced effects at interfaces have on Ising superconductivity, and finally discuss the prospects for observing Ising superconductivity in bulk materials.
Optical grade bromide-based thin film electrolytes
Authors: Melchioni Nicola , Trupiano Giacomo , Tofani Giorgio , Bertini Riccardo , Mezzetta Andrea , Bianco Federica , Guazzelli Lorenzo , Beltram Fabio , Pomelli Christian Silvio , Roddaro Stefano , Tredicucci Alessandro , Paolucci Federico
Published: June 2023

Controlling the charge density in low-dimensional materials with an electrostatic potential is a powerful tool to explore and influence their electronic and optical properties. Conventional solid gates impose strict geometrical constraints to the devices and often absorb electromagnetic radiation in the infrared (IR) region. A powerful alternative is ionic liquid (IL) gating. This technique only needs a metallic electrode in contact with the IL, and the highest achievable electric field is limited by the electrochemical interactions of the IL with the environment. Despite the excellent gating properties, a large number of ILs are hardly exploitable for optical experiments in the mid-IR region because they typically suffer from low optical transparency and degradation in ambient conditions. Here, we report the realization of two electrolytes based on bromide ILs dissolved in polymethyl methacrylate (PMMA). We demonstrate that such electrolytes in the form of thin films can induce state-of-the-art charge densities as high as 20×1015 cm−2 with an electrochemical window of [−1V, 1V] in vacuum. Thanks to the low water absorption of PMMA, they work both in vacuum and in ambient atmosphere after a simple vacuum curing. Furthermore, our electrolytes can be spin-coated into flat thin films with optical transparency in the range from 600 to 4000 cm–1. Thanks to these properties, these electrolytes are excellent candidates to fill the gap as versatile gating layers for electronic and mid-IR optoelectronic devices.
Resource-efficient digital characterization and control of classical non-Gaussian noise
Authors: Dong Wenzheng , Paz-Silva Gerardo A. , Viola Lorenza
Published: June 2023

We show the usefulness of frame-based characterization and control [PRX Quantum 2, 030315 (2021)] for non-Markovian open quantum systems subject to classical non-Gaussian dephasing. By focusing on the paradigmatic case of random telegraph noise and working in a digital window frame, we demonstrate how to achieve higher-order control-adapted spectral estimation for the noise-optimized dynamical decoupling design. We find that, depending on the operating parameter regime, control that is optimized based on non-Gaussian noise spectroscopy can substantially outperform standard Walsh decoupling sequences as well as sequences that are optimized based solely on Gaussian noise spectroscopy. This approach is also intrinsically more resource-efficient than frequency-domain comb-based methods.
Acoustic modes of self-excited cavitating waterjets on rock erosion
Authors: Chamorro Leonardo P.
Published: June 2023

This study experimentally investigates the impact of passive acoustic excitation modes from self-excited cavitating waterjet clouds on erosive patterns using high-speed imaging, scanning electron microscopy, and macroscopic three-dimensional scanning. Basalt, granite, and sandstone were used to study erosion and breaking mechanisms under various excitation modes, including sub-harmonic, fundamental, double-harmonic, and a case without feedback based on the primary cavitation cloud shedding frequency. Proper orthogonal decomposition of high-speed snapshots revealed that the cavitation cloud shed primary and secondary modes with passive acoustic excitation. The fundamental excitation mode promoted the primary cavitation cloud's volume and development, and energy transfers from secondary to primary modes resulted in the maximum cavitation cloud volume inducing the best rock-breaking ability. Macroscopic and microscopic inspection of the rock coupons' topographies revealed that the breaking mechanism involves a continuous peeling off of mineral grains under the cavitation cloud's impact.
Inhibition of vibrational energy flow within an aromatic scaffold via heavy atom effect
Authors: Hassani Majid , Mallon Christopher J. , Monzy Judith N. , Schmitz Andrew J. , Brewer Scott H. , Fenlon Edward E. , Tucker Matthew J.
Published: June 2023

The regulation of intramolecular vibrational energy redistribution (IVR) to influence energy flow within molecular scaffolds provides a way to steer fundamental processes of chemistry, such as chemical reactivity in proteins and design of molecular diodes. Using two-dimensional infrared (2D IR) spectroscopy, changes in the intensity of vibrational cross-peaks are often used to evaluate different energy transfer pathways present in small molecules. Previous 2D IR studies of para-azidobenzonitrile (PAB) demonstrated that several possible energy pathways from the N3 to the cyano-vibrational reporters were modulated by Fermi resonance, followed by energy relaxation into the solvent [Schmitz et al., J. Phys. Chem. A 123, 10571 (2019)]. In this work, the mechanisms of IVR were hindered via the introduction of a heavy atom, selenium, into the molecular scaffold. This effectively eliminated the energy transfer pathway and resulted in the dissipation of the energy into the bath and direct dipole–dipole coupling between the two vibrational reporters. Several structural variations of the aforementioned molecular scaffold were employed to assess how each interrupted the energy transfer pathways, and the evolution of 2D IR cross-peaks was measured to assess the changes in the energy flow. By eliminating the energy transfer pathways through isolation of specific vibrational transitions, through-space vibrational coupling between an azido (N3) and a selenocyanato (SeCN) probe is facilitated and observed for the first time. Thus, the rectification of this molecular circuitry is accomplished through the inhibition of energy flow using heavy atoms to suppress the anharmonic coupling and, instead, favor a vibrational coupling pathway.
Experimental studies on pressure drag and aerodynamic noise of cylinder with porous coatings
Authors: Xu Chen , Wang Chao , Mao Yijun , Jiang Shujie
Published: June 2023

Previous numerical studies hold inconsistent viewpoints of the porous coating on a circular cylinder reducing or increasing drag, and the present experimental study aims to clarify this argument. Additionally, a common viewpoint is that the porous coatings can suppress both the near-field wall pressure fluctuations and far-field acoustic pressure, but optimal parameters of the porous materials are still unclear. In this paper, the experimental studies reveal effects of three parameters, i.e., incoming flow velocity, pores per inch, and thickness of metal foams, on the pressure drag, wall pressure fluctuations, and associated noise level.
Thermodynamic analysis of absorption refrigeration cycles by parabolic trough collectors
Authors: Albaker Abdullah , Carbajal Nestor Cuba , Athó Manuel Octavio Fernández , Fernandez Anderson Nuñez , Laime Maria Del Carmen Delgado , Echavarria Ani Mary Borda , Alayi Reza , Aladdin Morteza
Published: June 2023

The purpose of this study is to numerically investigate the performance of a solar physical surface absorption cooling system, in which activated carbon/methanol is used as a working pair, which is placed inside a parabolic-shaped solar collector. The governing mathematical model of this issue is based on the equations of conservation of mass, conservation of energy, and thermodynamics of the physical surface absorption process. The equations are discretized using the fully implicit finite difference method, and the Fortran computer program was simulated. A comparison with the results of previous laboratory and numerical studies validated this model. At each point in the bed, the temperature, pressure, and mass of the refrigerant absorbed during the physical surface absorption/discharge process were calculated. In addition, the effects of the bed diameter, amount of solar radiation, source temperature, temperature, and pressure of the evaporator and condenser were investigated on the solar performance coefficient and the specific cooling power of the system. According to the built laboratory model and the working conditions of the system, the solar performance coefficient and the specific cooling capacity of the system are equal to 0.12 and 45.6 W/kg, respectively.
Sigmoid function generator using stochastic adiabatic superconductor logic
Authors: Luo Wenhui , Chen Olivia , Yoshikawa Nobuyuki , Takeuchi Naoki
Published: June 2023

Stochastic-computing-based artificial neural networks (SC-ANNs) can be used to perform hardware- and energy-efficient neuromorphic computing. We have been developing SC-ANNs using an energy-efficient superconductor logic family, namely, adiabatic quantum-flux-parametron (AQFP) logic. AQFP logic is suitable as a building block for SC-ANNs since it can perform stochastic operations with extremely small energy dissipation. In this Letter, we propose and demonstrate a sigmoid function generator (SFG) for AQFP SC-ANNs, which we refer to as the AQFP SFG. An SFG is an important circuit in neural networks that generates outputs from the sum of weighted inputs in accordance with the sigmoid function. The AQFP SFG performs the sigmoid function using a finite state machine based on an AQFP buffer coupled to a flux storage loop. We experimentally demonstrate that the AQFP SFG generates output signals from stochastic bitstreams in accordance with the sigmoid function and that the characteristics of the sigmoid function can be controlled by a bias current. Furthermore, we show that the AQFP SFG operates with small power dissipation due to its simple structure.
Long-distance transport of hot carriers due to acoustic phonon bottleneck in PbSe with room-temperature sensitive mid-infrared sensing
Authors: Cheng Zhe , Wu Shiteng , Jiang Yiqi , Wu Xing , Qiu Mengchun , Li Qinliang , Shen Yun , Yu Kuai , Wang Li , Wang Qisheng
Published: June 2023

In the optoelectronic conversion process of semiconductors, the photo-excited carriers with energy higher than energy band edge, i.e., hot carriers, have always fast (picoseconds scale) dissipated within 100 nanometers distance through lattice scattering. Specifically, the hot carriers relaxation accounts for more than 60% energy loss in narrow bandgap semiconductor. Herein, we observe an ultralong transport of hot carriers (558 nm) by local light excitation in single-crystalline thermoelectric semiconductor PbSe via the time-resolved reflectivity dynamics. The ultraweak phonon emission of PbSe results in a long-distance thermalized carriers transport due to acoustic phonon bottleneck. Furthermore, the hot carriers effect gives rise to a self-driven (zero bias), fast (900 ns), and sensitive (D* = 1.1 × 1010 cm Hz1/2 W−1 at 3.3 μm) mid-infrared detection and imaging at room temperature. Our discovery provides an insight into optoelectronic conversion mechanism of narrow bandgap thermoelectric semiconductors with intriguing optoelectronic applications.
Widespread partisan gerrymandering mostly cancels nationally, but reduces electoral competition
Authors: Kenny Christopher T. , McCartan Cory , Simko Tyler , Kuriwaki Shiro , Imai Kosuke
Published: June 2023

Congressional district lines in many US states are drawn by partisan actors, raising concerns about gerrymandering. To separate the partisan effects of redistricting from the effects of other factors including geography and redistricting rules, we compare possible party compositions of the US House under the enacted plan to those under a set of alternative simulated plans that serve as a nonpartisan baseline. We find that partisan gerrymandering is widespread in the 2020 redistricting cycle, but most of the electoral bias it creates cancels at the national level, giving Republicans two additional seats on average. Geography and redistricting rules separately contribute a moderate pro-Republican bias. Finally, we find that partisan gerrymandering reduces electoral competition and makes the partisan composition of the US House less responsive to shifts in the national vote.
A linker protein from a red-type pyrenoid phase separates with Rubisco via oligomerizing sticker motifs
Authors: Oh Zhen Guo , Ang Warren Shou Leong , Poh Cheng Wei , Lai Soak-Kuan , Sze Siu Kwan , Li Hoi-Yeung , Bhushan Shashi , Wunder Tobias , Mueller-Cajar Oliver
Published: June 2023

The slow kinetics and poor substrate specificity of the key photosynthetic CO
2
-fixing enzyme Rubisco have prompted the repeated evolution of Rubisco-containing biomolecular condensates known as pyrenoids in the majority of eukaryotic microalgae. Diatoms dominate marine photosynthesis, but the interactions underlying their pyrenoids are unknown. Here, we identify and characterize the Rubisco linker protein PYCO1 from
Phaeodactylum tricornutum
. PYCO1 is a tandem repeat protein containing prion-like domains that localizes to the pyrenoid. It undergoes homotypic liquid–liquid phase separation (LLPS) to form condensates that specifically partition diatom Rubisco. Saturation of PYCO1 condensates with Rubisco greatly reduces the mobility of droplet components. Cryo–electron microscopy and mutagenesis data revealed the sticker motifs required for homotypic and heterotypic phase separation. Our data indicate that the PYCO1–Rubisco network is cross-linked by PYCO1 stickers that oligomerize to bind to the small subunits lining the central solvent channel of the Rubisco holoenzyme. A second sticker motif binds to the large subunit. Pyrenoidal Rubisco condensates are highly diverse and tractable models of functional LLPS.
Intravenous immunoglobulin for recalcitrant subacute cutaneous lupus erythematosus
Authors: Kreuter A , Hyun J , Altmeyer P , Gambichler T.
Published: June 2023

No abstract available
Disseminated cryptococcosis in an elderly woman
Authors: Rodríguez-Lozano J , Almagro M , Del Pozo , Mosquera J , Fernández-Jorge B , Paradela S , Fonseca E.
Published: June 2023

No abstract available
Scrotal eczema-like lesion of secondary syphilis in an HIV-positive patient
Authors: Kang SH , Lee D , Park JH , Kang MS , Cho SH , Park SW.
Published: June 2023

No abstract available
Disseminated porokeratosis palmaris and plantaris treated with imiquimod cream to prevent malignancy
Authors: Jensen JM , Egberts F , Proksch E , Hauschild A.
Published: June 2023

No abstract available
A superficial form of malignant peripheral nerve sheath tumour associated with segmental neurofibromatosis
Authors: Li K , Won CH , Moon SE.
Published: June 2023

No abstract available
Strategies for resolving conflicts in the multicultural educational environment (Estrategias de resolución de conflictos en entornos educativos multiculturales)
Authors: Avagimyan Angela , Tugelbayeva Lyaila , Shagivaleeva Guzalia , Savchenko Irina
Published: June 2023

There are some problems, like poor academic performance, adaptation to a new cultural environment and a question of conflict resolution, in today’s multicultural classrooms. This study relied on observation and interviews. It was attended by 275 students and 65 teachers. The teachers involved in the experiment were asked to make reports and were interviewed. The results showed that 86% of teachers have a positive attitude towards multicultural education, versus 2% negative and 12% neutral; 69% of teachers reported that they do not see significant differences between groups that contain foreign students and those that do not. A model to develop basic conflict resolution competencies in teachers to deal with a multicultural student environment has been described in the study. The model consists of three stages: theoretical, practical and real cases. The results of the research can be useful for students, teachers, administrations of universities and schools, psychologists, parents, etc.
A novel approach to determining the hydrodynamic resistance of droplets in microchannels using active control and grey-box system identification
Authors: Hébert Marie , Huissoon Jan P , Ren Carolyn L
Published: June 2023

Inaccurate prediction of droplet hydrodynamic resistance has a profound impact on droplet chip performance and lengthens the iterative design process. Previous studies measuring droplet resistance use various approaches such as interface comparison to quantify flow rate, and pressure taps; all these methods are classified as passive. Although each study supports well their own findings, the wide variety of conditions such as channel geometry and use of surfactant in combination with the difficulty in quantifying the droplet resistance leads to poor consensus across the different studies. Overall guidelines would be broadly beneficial to the community, but are currently fairly crude, with a rule of thumb of 2 to 5 times resistance increase. The active droplet control platform previously developed enables a novel approach that is herein confirmed as promising. This proof-of-concept study focuses on verifying this approach that employs a system identification method to determine the hydrodynamic resistance of a channel containing a single droplet, from which the droplet resistance is retrieved. This method has the potential to be further applied to a large variety of conditions, and most importantly, to non-Newtonian fluids once key limitations are overcome to improve measurement resolution. The current results qualitatively agree with the literature and demonstrate the promising future for this novel active approach to quantifying droplet resistance.
Investigating capacitive flexible tactile sensor with a wide measuring range using PVDF and conductive sponge
Authors: Dong Yukun , Yao Tao , Lu Haiyang , Wang Zhihua
Published: June 2023

Flexible tactile sensors have important application value in the field of artificial intelligence and internet of things. At present, it is a great challenge for tactile sensors to maintain high sensitivity and stability in a large pressure range. This article proposes a flexible capacitive tactile sensor with high sensitivity and large measuring range, which has a sandwich structure. The purpose of this paper is to determine the relationship between the thickness, surface microstructure, sensitivity, and sensing range of poly(vinylidene fluoride) (PVDF) films. The sensor uses conductive sponge with a microstructure surface and an ultra-thin PVDF film as the electrode and dielectric layer, respectively, and provides a comprehensive study in terms of sensor design, theoretical calculation, computer simulation and applications. The minimum detection limit of the sensor are tested by sound vibration, needle blowing, and human physiological signals. It has been shown that the thicker the PVDF film, the lower the sensitivity and the wider the sensing range. The proposed sensor can accurately identify physiological signals such as respiration, pulse and swallowing, and can perceive the softness, hardness and weight of the object as well as identifying the grasping posture. Moreover, the sensor has the characteristics of short response time, good recoverability and stability.
A spin–orbit configuration interaction study of the low-lying electronic states of the diatomic lithium antimonide cation
Authors: Hu Zhuo-Jin , Wu Jin-Peng , Jiang Rong-Yao , Chen Shan-Jun , Li Song
Published: June 2023

High-level ab initio calculations were performed to determine the structural features, electronic characteristics and transitional properties of LiSb+, which is a hitherto experimentally unknown diatomic cation. We acquired and evaluated the potential energy curves, spectroscopic constants and vibrational energy levels for low-lying Λ-S electronic states and their related Ω states. The spin–orbit coupling effect has a slight impact on these states. Transitional properties, such as transition dipole moments, Einstein coefficients, Franck–Condon factors and vibrational branching ratios, as well as the radiative lifetimes of transitions from excited Ω states to the ground state, have been identified and discussed. We anticipate that these prognostic results will act as guidelines for future research.
Influence of compressive uniaxial strain on the piezoelectric response of wurtzite crystals
Authors: Benbedra Abdesamed , Meskine Said , Boukortt Abdelkader , Hayn Roland , Abbassa Hamza
Published: June 2023

We present a computational study of the crystal structure and electric polarization of strained wurtzite III–V nitrides and II–VI oxides, performed in the context of density functional theory and the Berry phase method. The main goal is to investigate the degree to which the lattice parameters, piezoelectric polarization, and piezoelectric constant can be affected by compressive uniaxial strain along the hexagonal c-axis. We show that imposing such strain enhances the piezoelectric response, with both polarization and piezoelectric coefficient increasing from their equilibrium values. The internal parameter of the wurtzite structure also increases with uniaxial strain and eventually becomes equal to 0.5, resulting in a phase transition into the layered hexagonal structure. Furthermore, we discuss the physical origin behind the enhanced piezoelectricity, showing that the enhancement is caused by a strong increase in the response of the internal parameter to strain.
Harmonic generation in magnetized plasma for electromagnetic wave propagating parallel to external magnetic field
Authors: Dhalia Trishul , Juneja Rohit , Prasad Goswami Laxman , Maity Srimanta , Das Amita
Published: June 2023

Harmonic generation has always been of fundamental interest in the study of the nonlinear nature of any physical system. In the present study, particle-in-cell simulations have been carried out to explore the harmonic generation of electromagnetic (EM) waves in a magnetized plasma. EM wave propagation is chosen to be parallel to the applied external magnetic field. The simulations show the excitation of odd higher harmonics of right circularly polarized waves and left circularly polarized waves when the incident wave is linearly polarized. The harmonic generation is maximum when the incident EM wave frequency matches the electron cyclotron frequency. When the incident EM wave has a circular polarization, no harmonics get excited. A theoretical understanding of these observations has also been provided. The studies thus show that by appropriately tailoring plasma parameters, EM waves of higher frequencies and the desired nature of circular polarization can be generated.
A DFT study of electron–phonon interactions for the
C2CN
and
VNNB
defects in hexagonal boron nitride: investigating the role of the transition dipole direction
Authors: Sharman K , Golami O , Wein S C , Zadeh-Haghighi H , Rocha C G , Kubanek A , Simon C
Published: June 2023

Quantum emitters in two-dimensional hexagonal boron nitride (h-BN) have generated significant interest due to observations of ultra-bright emission made at room temperature. The expectation that solid-state emitters exhibit broad zero-phonon lines at elevated temperatures has been put in question by recent observations of Fourier transform (FT) limited photons emitted from h-BN flakes at room temperature. All decoupled emitters produce photons that are directed in-plane, suggesting that the dipoles are perpendicular to the h-BN plane. Motivated by the promise of an efficient and scalable source of indistinguishable photons that can operate at room temperature, we have developed an approach using density functional theory (DFT) to determine the electron-phonon coupling for defects that have in- and out-of-plane transition dipole moments. Our DFT calculations reveal that the transition dipole for the

C
2

C
N

defect is parallel to the h-BN plane, and for the

V
N

N
B

defect is perpendicular to the plane. We calculate both the phonon density of states and the electron–phonon matrix elements associated with the h-BN defective structures. We find no indication that an out-of-plane transition dipole by itself will result in the low electron–phonon coupling that is expected to produce FT-limited photons at room temperature. Our work provides direction to future DFT software developments and adds to the growing list of calculations relevant to researchers in the field of solid-state quantum information processing.