bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the scattering matrix method for investigating the propagation characteristics of terahertz waves in magnetized dusty plasma
Authors: Zhang Lei , Wu Yuhang , Wan Xiaohuan , Li Xiang , Zhao Yuexing , Fan Xiaobei , Wang Jing , Shi Yuren
Published: January 2023

A scattering matrix method is applied to investigate propagation characteristics of oblique incident terahertz waves into magnetized dusty plasmas. The numerical results agree well with those given by the Wenzell–Kramer–Brillouin method. Three different electron density distributions are taken into account, and both the right- and left-hand circularly polarized (RCP and LCP) waves are analyzed. Transmission properties of terahertz (THz) waves with different physical parameters, such as external magnetic, dust particle density, and dust particle radius, are discussed systematically. There exists a transmissivity peak at the lower-frequency band for RCP waves when an external magnetic field is presented. The value of the peak nearly keeps invariant, and its location moves toward the higher-frequency direction if the magnetic field enhances. Increasing the dust particle density or radius can make the value of a transmissivity peak larger. The transmissivity of higher-frequency RCP THz waves decreases if the external magnetic field increases. However, for LCP waves, there is no transmissivity peak. It increases monotonously as the frequency of a THz wave increases. Different from the RCP waves, enhancing the external magnetic field is better for the LCP waves to penetrate the dusty plasma. Our results may provide some theoretical basis for alleviating the problem of “blackout.”
Development of a removable three-dimensional magnetic probe system for measuring field null on the NanChang Spherical Tokamak
Authors: Ouyang T. B. , Chen H. , Liu S. Q. , Chen X. C. , Yang X. S. , Hou M. , Zhao Z. Y.
Published: January 2023

The field null configuration of a poloidal magnetic field is one of the critical conditions for achieving Ohmic breakdown during the initial discharge of a new tokamak. The issue of the Ohmic breakdown on the NanChang Spherical Tokamak (NCST) is still not solved satisfactorily although plasma currents of about 2 kA were found. Hence, a removable three-dimensional magnetic probe (RTMP) system consisting of 25 magnetic probes was designed, calibrated, and constructed on the NCST to evaluate the field null inside a vacuum vessel. After repeated tests, the RTMP system exhibited outstanding performance in terms of accuracy and stability with errors of about 1%. Meanwhile, the RTMP system successfully measured the toroidal field (TF) coil ripples at the magnetic axis. During experiments, the stray field arising from the TF coil implied a strong link between the flexible connection of the TF coil and the Ohmic breakdown on the NCST. After the field null was effectively modified by using a new flexible connection of the TF coil and controlling the induced current in the poloidal field coil, the NCST tokamak reproducibly obtained 20 kA plasma current with the limiter configuration during the plasma current flat-top phase.
Ray-tracing analysis for combined Doppler backscattering and cross-polarization scattering diagnostic on the HL-2M tokamak
Authors: Zhou Yu , Tong Ruihai , Zhong Wulyu , Tan Yi , Shi Zhongbing , Jiang Min , Wen Jie , Yang Zengchen , Shi Peiwan , Liang Anshu , Yu Xin , Shen Yuqi , Xue Guanqun , Deng Weichu
Published: January 2023

To measure plasma density and magnetic fluctuations on the HL-2M tokamak simultaneously, a new diagnostic system combining Doppler backscattering (DBS) and cross-polarization scattering (CPS) is under development. It is essential to understand the propagation of injected and scattered rays to support the electronic/quasi-optical design and subsequent interpretation of the detected signals of the multi-channel DBS/CPS measurements. Thus, ray-tracing analysis with the axisymmetric ray-tracing code BORAY has been performed to estimate the scattering location and wavenumbers of the density and magnetic fluctuations. In addition, the influence of accordance between toroidal and poloidal launch angles is investigated. The received DBS/CPS signal quality can be improved by matching the parallel wavenumber in the direction of magnetic field lines.
Injectable heat-sensitive nanocomposite hydrogel for regulating gene expression in the treatment of alcohol-induced osteonecrosis of the femoral head
Authors: Fu Zherui , Lai Yi , Zhuang Yaping , Lin Feng
Published: January 2023

For repairing lesions, it is important to recover physiological and cellular activities. Gene therapy can restore these activities by regulating the expression of genes in lesion cells; however, in chronic diseases, such as alcohol-induced osteonecrosis of the femoral head (ONFH), gene therapy has failed to provide long-term effects. In this study, we developed a heat-sensitive nanocomposite hydrogel system with a secondary nanostructure that can regulate gene expression and achieve long-term gene regulation in lesion cells. This nanocomposite hydrogel exists in a liquid state at 25 °C and is injectable. Once injected into the body, the hydrogel can undergo solidification induced by body heat, thereby gaining the ability to be retained in the body for a prolonged time period. With the gradual degradation of the hydrogel in vivo, the internal secondary nanostructures are continuously released. These nanoparticles carry plasmids and siRNA into lesion stem cells to promote the expression of B-cell lymphoma 2 (inhibiting the apoptosis of stem cells) and inhibit the secretion of peroxisome proliferators-activated receptors γ (PPARγ, inhibiting the adipogenic differentiation of stem cells). Finally, the physiological activity of the stem cells in the ONFH area was restored and ONFH repair was promoted. In vivo experiments demonstrated that this nanocomposite hydrogel can be indwelled for a long time, thereby providing long-term treatment effects. As a result, bone reconstruction occurs in the ONFH area, thus enabling the treatment of alcohol-induced ONFH. Our nanocomposite hydrogel provides a novel treatment option for alcohol-related diseases and may serve as a useful biomaterial for other gene therapy applications.
Magneto-thermal conductivity effect and enhanced thermoelectric figure of merit in Ag2Te
Authors: Hirata Keisuke , Kuga Kentaro , Matsunami Masaharu , Zhu Minyue , Heremans Joseph P. , Takeuchi Tsunehiro
Published: January 2023

In this study, we report a large magneto-thermal conductivity effect, potentially usable in heat flow switches and thermoelectric devices, in Ag2Te over a wide temperature range, including room temperature. When a magnetic field of μ0H = 9 T is applied to Ag2Te at 300 K along the direction perpendicular to the heat and electric currents, the thermal conductivity κ decreases by a remarkable 61%. This effect is mainly caused by the suppressed electronic thermal conductivity in association with a significant magnetoresistance effect, but the suppression of the thermal conductivity is larger than that of the electrical conductivity, presumably due to a field-induced decrease in the Lorenz ratio. Its very low lattice thermal conductivity, as low as 0.5 W m−1 K−1, also greatly contributes to the large relative magneto-thermal conductivity effect. The significant decrease in thermal conductivity and the 18% increase in the Seebeck coefficient S lead to a nearly 100% increase in the thermoelectric figure of merit zT = S2σTκ−1 despite the 43% decrease in electrical conductivity σ.
Electro-mechanical tuning of high-Q bulk acoustic phonon modes at cryogenic temperatures
Authors: Campbell William , Galliou Serge , Tobar Michael E. , Goryachev Maxim
Published: January 2023

We investigate the electromechanical properties of quartz bulk acoustic wave resonators at extreme cryogenic temperatures. By applying a DC bias voltage, we demonstrate broad frequency tuning of high-Q phonon modes in a quartz bulk acoustic wave cavity at cryogenic temperatures of 4 K and 20 mK. More than 100 line-widths of tuning of the resonance peak without any degradation in loaded quality factor, which are as high as 1.73×109, is seen for high order overtone modes. For all modes and temperatures, the observed coefficient of frequency tuning is ≈ 3.5 mHz/V per overtone number n corresponding to a maximum of 255.5 mHz/V for the n = 73 overtone mode. No degradation in the quality factor is observed for any value of an applied biasing field.
Modeling acoustic emissions and shock formation of cavitation bubbles
Authors: Denner Fabian , Schenke Sören
Published: January 2023

Despite significant progress in understanding and foretelling pressure-driven bubble dynamics, models that faithfully predict the emitted acoustic waves and the associated shock formation of oscillating or collapsing bubbles have received comparably little attention. We propose a numerical framework using a Lagrangian wave tracking approach to model the acoustic emissions of pressure-driven bubbles based on the Kirkwood–Bethe hypothesis and under the assumption of spherical symmetry. This modeling approach is agnostic to the equation of the state of the liquid and enables the accurate prediction of pressure and velocity in the vicinity of pressure-driven bubbles, including the formation and attenuation of shock fronts. We validate and test this new numerical framework by comparison with solutions of the full Navier–Stokes equations and by considering a laser-induced cavitation bubble as well as pressure-driven microbubbles in excitation regimes relevant to sonoluminescence and medical ultrasound, including different equations of state for the liquid. A detailed analysis of the bubble-induced flow field as a function of the radial coordinate r demonstrates that the flow velocity u is dominated by acoustic contributions during a strong bubble collapse and, hence, decays predominantly with u∝r−1, contrary to the frequently postulated decay with u∝r−2 in an incompressible fluid.
Molecular dynamics study of thermal transport across Ga2O3–diamond interfaces
Authors: Petkov Alexander , Mishra Abhishek , Pomeroy James W. , Kuball Martin
Published: January 2023

Integration of β-Ga2O3 with high thermal conductivity materials such as diamond has been considered due to β-Ga2O3's low and anisotropic thermal conductivity, reaching only 27 W m–1 K–1. However, the effect of crystallographic orientation on thermal interface resistance has not been studied extensively, which is relevant for potential device architectures. In this work, we use molecular dynamics simulations to investigate the crystal orientation-dependent thermal boundary resistance (TBR) across van der Waals bonded diamond–β-Ga2O3 and ionicly bonded amorphous Al2O3–β-Ga2O3 interfaces. Al2O3 is often used as interlayer to grow diamond onto Ga2O3. We find that TBR values across the van der Waals interface may vary by up to 70% depending on the orientation of the β-Ga2O3, while the Al2O3–β-Ga2O3 TBR values remain around 0.9 ± 0.3 m2 KGW−1. We, thus, conclude on the optimal direction of β-Ga2O3 to use for reducing the TBR in these heterostructures.
Numerical study of rotor unsteady forces and noise due to ingestion of grid-generated turbulence
Authors: Wu Jiafeng , Yangzhou Jianyun , Ma Zhaokai , Huang Xun
Published: January 2023

In many aeronautics and marine applications, the unsteady forces generated by propulsion rotors due to turbulence ingestion are a significant source of noise and create serious concerns. The understanding of rotor turbulence ingestion and the rotor noise generation mechanisms is vital to achieve an optimal design or apply noise control strategy. The current study is the first attempt to numerically investigate an underwater rotor ingesting grid-generated turbulence by large eddy simulation combined with the Ffowcs-Williams and Hawkings equation. The flow characteristics of two directly simulated turbulence grids with a mesh spacing of 4 and 6 in. are investigated and proved to be adequate for the rotor turbulence ingestion study. The simulated unsteady force spectra of the rotor show better agreement with the experimental results in terms of amplitudes and frequency ranges of the first haystack and broadband components compared to previous theoretical and numerical studies. The unsteady forces and noise of the rotor downstream of the 4-in. grid are slightly higher than those downstream of the 6-in. grid. A far-field noise prediction approach based on the time derivatives of the rotor axial and radial unsteady forces are investigated and validated. The far-field noise spectra and the rotor noise directivities predicted by the time derivative approach agree well with the Ffowcs-Williams and Hawkings equation in the main frequency range of underwater rotor noise. The noise directivities are found to be dominated by axial force related dipole sources.
Effects of hydrophobic slips in non-uniform electrokinetic transport of charged viscous fluid in nozzle-diffuser
Authors: Majhi M. , Nayak A. K. , Sahoo Subhajyoti
Published: January 2023

The mixing efficiency and electro-osmotic flow enhancement over a hydrophobic structured microchannel with nozzle-diffuser under an external electric field is studied. The interfacial surface zeta potential is varied to generate a strong convection effect between two injecting fluids from the reservoirs for a wide range of Reynolds numbers. The Poisson–Nernst–Plank model is incorporated to deal with thick and thin diffuse layers formed by a non-Newtonian electrolyte solution for the numerical simulation of the mobility of ions. To avoid the high-pressure drop complications in the computation, we have scaled the mixing efficiency with the average pressure drop. The analytical validation of the velocity and potential for thin and thick electric double layer with the existing experimental results corroborated and bridged the performance of the present model to achieve faster mixing by reducing pressure gradient. It is demonstrated that hydrodynamic slip increases the flow velocity producing larger mobility; however, the heterogeneous zeta potential generates a backflow that prevents the driving fluids leading to higher mixing efficiency, discussed in the first phase of the work. It is found that the mixing performance of Newtonian fluid is maximum for a nozzle-diffuser-shaped microchannel when all other physical parameters are constant. In the next phase, the mixing performance of shear thickening, shear thinning, and Newtonian fluid has been discussed for various physio-chemical parameters, i.e., slip length, Debye parameter, channel conical angle/slope, and heterogeneous zeta potential strength. The mixing efficiency and the pressure gradient decrease with the increase in the Debye parameter and the slip length. It is observed that the mixing efficiency can further be enhanced by increasing the heterogeneity of zeta potential strength and channel conical angle. This study can be used as a benchmark model for fabrication of chaotic mixers in hydrophobic slips with wall-mounted heterogeneous zeta potential and can be suitable for handling the power-law fluids.
Numerical study on the effect of airflow on powder mixing in a container blender
Authors: Shi Qi , Sakai Mikio
Published: January 2023

Powder mixing is critical in many industries. Despite the wide variety of available mixers, the container blender is favored in industries due to easy manufacturing and convenient operation. As fine powders are frequently encountered in practical mixing, the presence of air during mixing may significantly impact the process. However, a scientific understanding of air–particle interactions in powder mixing has not been established so far. From a physical view, the air drag force on particles might be significant when the gas velocity is high and the particles are fine. Therefore, this novel study numerically investigates the effects of particle size and air presence on powder mixing under typical conditions, such that the relationship between particle–fluid dynamics and mixing performance is clarified for the first time. In the calculation, our advanced computational fluid dynamics–discrete element method, namely, the flexible Eulerian–Lagrangian method with an implicit algorithm, is utilized. To examine the effect of particle size on powder mixing, the coarse-grained discrete element method is employed for fine particle systems. Through the advanced numerical framework, the effect of airflow on powder mixing can be discussed in depth. The numerical results show that airflow accelerates the mixing of fine particles under the investigated rotation speeds. Based on the calculation results of the particle kinetics and fluid velocity distribution, it is clarified that the accelerated mixing results from the fine particle movement under air entrainment. How the movement of fine particles is developed is also elucidated by the continuously circulating gas flow and fluid drag force. Thus, this study provides a new understanding of the effects of airflow on powder mixing, which has not been scientifically clarified in previous studies.
Energy localization efficiency in 1,3,5-trinitro-2,4,6-triaminobenzene pore collapse mechanisms
Authors: Hamilton Brenden W. , Germann Timothy C.
Published: January 2023

Atomistic and continuum scale modeling efforts have shown that the shock-induced collapse of porosity can occur via a wide range of mechanisms dependent on pore morphology, the shockwave pressure, and material properties. The mechanisms that occur under weaker shocks tend to be more efficient at localizing thermal energy but do not result in high, absolute temperatures or spatially large localizations compared to mechanisms found under strong shock conditions. However, the energetic material 1,3,5-trinitro-2,4,6-triaminobenzene (TATB) undergoes a wide range of collapse mechanisms that are not typical of similar materials, leaving the collapse mechanisms and the resultant energy localization from the collapse, i.e., hotspots, relatively uncharacterized. Therefore, we present the pore collapse simulations of cylindrical pores in TATB for a wide range of pore sizes and shock strengths that trigger viscoplastic collapses that occur almost entirely perpendicular to the shock direction for weak shocks and hydrodynamic-like collapses for strong shocks that do not break the strong hydrogen bonds of the TATB basal planes. The resulting hotspot temperature fields from these mechanisms follow trends that differ considerably from other energetic materials; hence, we compare them under normalized temperature values to assess the relative efficiency of each mechanism to localize energy. The local intra-molecular strain energy of the hotspots is also assessed to better understand the physical mechanisms behind the phenomena that lead to a latent potential energy.
Dynamics of vapor bubble condensation under directional ultrasonic actuation
Authors: Boziuk Thomas R. , Smith Marc K. , Glezer Ari
Published: January 2023

Direct-contact condensation of vapor bubbles injected into a subcooled liquid is enhanced using ultrasonic O(1 MHz) acoustic actuation. In the absence of actuation, the surface tension-driven pinch-off process of the vapor bubble from the injection orifice induces a liquid spear that travels upward through the bubble and ruptures the top interface to form a toroidal bubble. Similarly, the acoustic actuator produces a narrow high-intensity acoustic beam that deforms the top interface of the vapor bubble via radiation pressure to form a liquid spear that travels downward though the bubble and ruptures the bottom interface to form a toroidal bubble. Comparisons between the growth and collapse of vapor bubbles in these two cases were performed using high-speed video imaging and particle image velocimetry. The results show that the actuated bubble collapsed about 35% faster than the unactuated bubble. The flow fields around the bubbles induced by the motion of the liquid spears are similar in both cases. By comparing vapor bubbles under different subcooling conditions with an unactuated, noncondensing air bubble, it was shown that condensation at the liquid–vapor interface strongly influences bubble collapse times and the velocity field surrounding each of the bubbles and that these effects increase as the level of subcooling increases.
Self-diffusion and shear viscosity for the TIP4P/Ice water model
Authors: Baran Łukasz , Rżysko Wojciech , MacDowell Luis G.
Published: January 2023

With an ever-increasing interest in water properties, many intermolecular force fields have been proposed to describe the behavior of water. Unfortunately, good models for liquid water usually cannot provide simultaneously an accurate melting point for ice. For this reason, the TIP4P/Ice model was developed for targeting the melting point and has become the preferred choice for simulating ice at coexistence. Unfortunately, available data for its dynamic properties in the liquid state are scarce. Therefore, we demonstrate a series of simulations aimed at the calculation of transport coefficients for the TIP4P/Ice model over a large range of thermodynamic conditions, ranging from T = 245 K to T = 350 K, for the temperature, and from p = 0 to p = 500 MPa, for the pressure. We have found that the self-diffusion (shear viscosity) exhibits smaller (increased) values than TIP4P/2005 and experiments. However, rescaling the temperature with respect to the triple point temperature, as in a corresponding states plot, we find that TIP4P/Ice compares very well with TIP4P/2005 and experiment. Such observations allow us to infer that despite the different original purposes of these two models examined here, one can benefit from a vast number of reports regarding the behavior of transport coefficients for the TIP4P/2005 model and utilize them following the routine described in this paper.
Clathrate-like porous graphene/TiO2 composite with strong dielectric polarization for electromagnetic microwave absorption
Authors: Zhang Qiancheng , Du Zuojuan , Ding Zi Zhao , Liu Yu , Yue Jianling , Huang Xiaozhong , Chen Aililang
Published: January 2023

Porous carbon frameworks functionalized with multi-scale particles are an important approach in highly efficient microwave absorbent design since impedance matching and polarization/conductivity loss are well balanced. The absorbent with a versatile structure that is not easily deformed within application is still in need. In this work, open-cell porous graphene (PG) functionalized with TiO2 nanorods is synthesized by the solvothermal method, creating a high specific surface area structure. Complex electromagnetic parameters indicate that the introduction of TiO2 nanorods improves the microwave absorption (MA) performance by optimizing the impedance matching and enhancing the polarization relaxation due to the large numbers of PG@TiO2 interfaces. Polarization loss plays a dominant role in microwave attenuation. In addition, the designed clathrate-like structure is anticipated to further attenuate the MA wave by multiple reflections and scatterings. Interface polarization and dipole polarization can be identified with frequencies in Cole–Cole plotting. The optimized PG@TiO2 composite with a thickness of 1.92 mm exhibits a minimum reflection loss of −55.10 dB at 14.29 GHz with a low filler ratio of 10 wt. %. This work is heuristic in the absorbent structure design and is helpful in enhancing and identification of polarization relaxation loss.
Emergent mixed antiferromagnetic state in MnPS3(1-x)Se3x
Authors: Han Hui , Lin Hong , Gan Wei , Liu Yucheng , Xiao Ruichun , Zhang Lei , Li Yang , Zhang Changjin , Li Hui
Published: January 2023

The discovery of magnetism in van der Waal (vdW) materials has aroused substantial interest in the exploration of magnetic interactions toward a two-dimensional (2D) limit. Here, we report the engineering of magnetic properties in MnPS3(1-x)Se3x compounds by substituting the non-magnetic chalcogenide S atoms with Se atoms. The anisotropic antiferromagnetic transition of MnPS3(1-x)Se3x compounds is gradually modulated by controlling the Se concentration, including the monotonic decrease in the Néel temperature and Curie–Weiss temperature with increasing Se concentration, and the Se concentration dependence of a spin-flop process. In addition, the magnetic phase diagram is established, in which an exotic mixed antiferromagnetic state appears due to the competition between the magnetic orderings in parent materials of MnPS3 and MnPSe3. Our findings validate the possibility of the manipulation of magnetic properties in magnetic vdW materials through the substitution of chalcogenide ions and pave the way toward the engineering of magnetic interactions and the designing of magnetic devices in two-dimensional magnetic vdW materials.
Metaball-Imaging discrete element lattice Boltzmann method for fluid–particle system of complex morphologies with case studies
Authors: Zhao Yifeng , Zhang Pei , Lei Liang , Kong Lingwei , Galindo-Torres S. A. , Li Stan Z.
Published: January 2023

Fluid–particle systems are highly sensitive to particle morphologies. While many attempts have been made on shape descriptors and coupling schemes, how to simulate particle–particle and particle–fluid interactions with a balance between accuracy and efficiency is still a challenge, especially when complex-shaped particles are considered. This study presents a Metaball-Imaging (MI) based Discrete Element Lattice Boltzmann Method (DELBM) for fluid simulations with irregular shaped particles. The major innovation is the MI algorithm to capture the real grain shape for DELBM simulations, where the Metaball function is utilized as the mathematical representation due to its versatile and efficient expressiveness of complex shapes. The contact detection is tackled robustly by gradient calculation of the closest point with a Newton–Raphson based scheme. The coupling with LBM is accomplished by a classic sharp-interface scheme. As for refiling, a local refiling algorithm based on the bounce back rule is implemented. Validations on the Jeffery orbit of ellipsoidal particles and three settling experiments of irregular-shaped natural cobblestones indicate the proposed model to be effective and powerful in probing micromechanics of irregular-shaped granular media immersed in fluid systems. The potential of this model on studies of shape-induced physical processes is further investigated with numerical examples that consider the drag and lift forces experienced by realistic particles, as well as the “drafting, kissing and tumbling” process of pairs of non-spherical particles.
Bathymetry and friction estimation from transient velocity data for one-dimensional shallow water flows in open channels with varying width
Authors: Hernández-Dueñas Gerardo , Moreles Miguel Angel , González-Casanova Pedro
Published: January 2023

The shallow water equations (SWE) model a variety of geophysical flows. Flows in channels with rectangular cross sections may be modeled with a simplified one-dimensional SWE with varying width. Among other model parameters, information about the bathymetry and friction coefficient is needed for the correct and precise prediction of the flow. Although synthetic values of the model parameters may suffice for testing numerical schemes, approximations of the bathymetry and other parameters may be required for specific applications. Estimations may be obtained by experimental methods, but some of those techniques may be expensive, time consuming, and not always available. In this work, we propose to solve the inverse problem to estimate the bathymetry and the Manning's friction coefficient from transient velocity data. This is done with the aid of a cost functional, which includes the SWE through Lagrange multipliers. We prove that the velocity data determine uniquely the derivative of the bathymetry in a linearized shallow water system. That is, the inverse problem is identifiable. The solution is obtained by solving the constrained optimization problem by a continuous descent method. The direct and the adjoint problems are both solved numerically using a second-order accurate Roe-type upwind scheme. Numerical tests are included to show the merits of the algorithm.
Effect of a textured surface on the occurrence and development of cavitation on the hydrofoil
Authors: Skripkin Sergey G. , Starinskiy Sergey V. , Tsoy Mikhail A. , Vasiliev Mikhail M. , Kravtsova Aleksandra Yu.
Published: January 2023

An experimental study of the cavitation flow around the National Advisory Committee for Aeronautics 0012 hydrofoil with different surface morphology was carried out in this work. The surface morphology was set by modern laser ablation technology. The average values and intensity of vapor–gas cavities were determined. It has been revealed that laser texturing delays the emerging cavitation and somewhat decreases its intensity at higher cavitation numbers. A decrease in the cavitation number leads to an increase in its intensity for a smooth hydrofoil in comparison with a rough one, which is also expressed in an increase in the frequency of cavities. The paper presents a comparison of the flow regime with equal cavitation numbers, which clearly describes the features of the development of a vapor–gas cavity on the suction side of the foil with different surface morphologies. The paper provides an explanation of the reasons for the influence of surface morphology on the development of cavities.
An efficient time-domain implementation of the multichromophoric Förster resonant energy transfer method
Authors: Zhong Kai , Nguyen Hoang Long , Do Thanh Nhut , Tan Howe-Siang , Knoester Jasper , Jansen Thomas L. C.
Published: January 2023

The excitation energy transfer (EET) process for photosynthetic antenna complexes consisting of subunits, each comprised of multiple chromophores, remains challenging to describe. The multichromophoric Förster resonance energy transfer theory is a popular method to describe the EET process in such systems. This paper presents a new time-domain method for calculating energy transfer based on the combination of multichromophoric Förster resonance energy transfer theory and the Numerical Integration of the Schrödinger Equation method. After validating the method on simple model systems, we apply it to the Light-Harvesting antenna 2 (LH2) complex, a light harvesting antenna found in purple bacteria. We use a simple model combining the overdamped Brownian oscillators to describe the dynamic disorder originating from the environmental fluctuations and the transition charge from the electrostatic potential coupling model to determine the interactions between chromophores. We demonstrate that with this model, both the calculated spectra and the EET rates between the two rings within the LH2 complex agree well with experimental results. We further find that the transfer between the strongly coupled rings of neighboring LH2 complexes can also be well described with our method. We conclude that our new method accurately describes the EET rate for biologically relevant multichromophoric systems, which are similar to the LH2 complex. Computationally, the new method is very tractable, especially for slow processes. We foresee that the method can be applied to efficiently calculate transfer in artificial systems as well and may pave the way for calculating multidimensional spectra of extensive multichromophoric systems in the future.
Aeroacoustic control mechanism on near-wall-wing of Aero-train based on plasma jet
Authors: Lai Chenguang , Tan Liangkui , Obayashi Shigeru
Published: January 2023

In this study, an aeroacoustic control mechanism of a plasma jet acting on a high-speed moving wing under a wing-in-ground effect is investigated. Moreover, a novel method is proposed to reduce the aeroacoustics of Aero-train wings. Numerical simulations of the aeroacoustics generated by flow around a National Advisory Committee for Aeronautics 4412 wing are performed under three different plasma excitation modes at four clearances with an incoming flow velocity of 0.3 Ma and an angle of attack of 5°. The results show that different plasma excitation modes interfere with the vortex generation and development in different ways to achieve aeroacoustic reduction. The UP excitation mode delays the airflow separation, delays the vortex generation and development, and reduces the vortex intensity. The BOTH excitation mode forces transverse vortices to transform into streamwise hairpin vortices and reduces the local pressure fluctuation intensity. Hence, plasma jets exhibit a good control effect on the peak aeroacoustics under different clearance conditions but result in the frequency shift effect of acoustic energy transfer to high frequencies. The modal analysis of the flow field of the three excitation conditions via a proper orthogonal decomposition method reveals that the trend of the modal change is similar for the three excitation conditions, and the change in each order of the modal corresponds to the energy decrease at the peak frequency and the energy increase at high frequencies.
The Auger spectrum of benzene
Authors: Jayadev Nayanthara K. , Ferino-Pérez Anthuan , Matz Florian , Krylov Anna I. , Jagau Thomas-C.
Published: January 2023

We present an ab initio computational study of the Auger electron spectrum of benzene. Auger electron spectroscopy exploits the Auger–Meitner effect, and although it is established as an analytic technique, the theoretical modeling of molecular Auger spectra from first principles remains challenging. Here, we use coupled-cluster theory and equation-of-motion coupled-cluster theory combined with two approaches to describe the decaying nature of core-ionized states: (i) Feshbach–Fano resonance theory and (ii) the method of complex basis functions. The spectra computed with these two approaches are in excellent agreement with each other and also agree well with experimental Auger spectra of benzene. The Auger spectrum of benzene features two well-resolved peaks at Auger electron energies above 260 eV, which correspond to final states with two electrons removed from the 1e1g and 3e2g highest occupied molecular orbitals. At lower Auger electron energies, the spectrum is less well resolved, and the peaks comprise multiple final states of the benzene dication. In line with theoretical considerations, singlet decay channels contribute more to the total Auger intensity than the corresponding triplet decay channels.
Internally heated convection of viscoplastic fluids in enclosures using a lattice Boltzmann method
Authors: Kefayati Gholamreza
Published: January 2023

Thermal convection driven by an internal heat source in a two-dimensional enclosure filled with viscoplastic fluids is investigated numerically. Two vertical side walls of the cavity are isotherms with the same low temperatures, while the horizontal walls are adiabatic and insulated. An exact Bingham model is applied in the constitutive equation for the viscoplastic fluid. A lattice Boltzmann method (LBM) is developed to solve the introduced non-dimensional macroscopic equations, and the derivations of the LBM are presented and discussed. The implemented LBM is validated against previous studies of internal natural convection. The effects of the Rayleigh–Roberts number, the Prandtl number, the aspect ratio of the cavity, and the inclined angle of the enclosure on the yielded/unyielded parts are investigated and reported. The maximum (or critical) Bingham (Bn) and yield (Y) numbers for the studied parameters are investigated through the defined Nusselt number. The results are depicted by the contours of isotherms, streamlines, yielded/unyielded zones, vorticity, and horizontal and vertical velocities. In addition, the temperatures and velocities in the middle of the cavity as well as the Nusselt number are shown and discussed. It was revealed that the maximum (or critical) yield number is independent of Rayleigh–Roberts and Prandtl numbers same as external natural convection. The values of the critical yield number decrease gradually as the inclined angle rises counterclockwise. However, the critical yield number enhances with the increase in the aspect ratio although the augmentation is not linear and steady.
Ferromagnetic exchange field-controlled band dispersions of non-Dirac electrons
Authors: Zhu Yingmei , Cui Qirui , Yang Hongxin
Published: January 2023

Using model analysis and first-principles calculations, we demonstrate that intrinsic ferromagnetic field of materials can effectively modulate the non-Dirac band dispersions. The four-bands k·p model illustrates that rotating magnetization from in-plane to out-of-plane lifts the degeneracy of band dispersions at Γ point, and spin components of lower or upper two bands tend to become identical as the enhancement of exchange field, which results in non-trivial topology. Moreover, we exemplify these phenomena in stanene-based systems, namely stanene/hematene heterostructure and half-hydrogen-passivated stanene, respectively. Some interesting spin-dependent transport behavior, such as large magnetoresistance and quantum anomalous hall effect, are achieved. These findings enrich the physics of non-Dirac electrons and provide promising routes for realizing effective manipulation of band dispersions via spin freedom.
Addressing security threats affecting primary healthcare service delivery and uptake in Nigeria
Authors: Agwu Prince , Onwujekwe Obinna
Published: January 2023

Background Security of health facilities in low- and middle-income countries (LMICs) is of vital importance in ensuring that health care can be provided in safe conditions. There is paucity of literature on the issue of threats to the personal safety of primary healthcare (PHC) providers and service users in Nigeria and what should be done. Thus, the current study seeks to fill this gap. Method Key-informant interviews with 12 health workers and non-participant observations were utilised for data collection in Enugu, Nigeria. Their responses were analysed using a descriptive qualitative analysis approach in structuring narratives in themes. Result There is lack of vital security infrastructure across the health facilities, and we recorded reports on armed robbery attacks, theft of drugs and other items, including a case of a stolen newborn. These findings are structured in three themes that reveal experienced threats in PHC facilities, their implications on health service delivery, and responses that can be taken to make PHC facilities safe. Conclusion Security challenges constrain both access and provision of essential and affordable healthcare services at the primary healthcare level in Enugu, Nigeria.
Burned vegetation recovery trajectory and its driving factors using satellite remote-sensing datasets in the Great Xing’An forest region of Inner Mongolia
Authors: Zhang Qiyue , Homayouni Saeid , Zhao Pengwu , Zhou Mei
Published: January 2023

Forest fire is one of the most important factors that alter a forest ecosystem’s biogeochemical cycle. Large-scale distributed burned areas lose their original vegetation structure and are more impacted by climate change in the vegetation recovery process, thus making it harder to restore their original vegetation structure. In this study, we used historical Landsat imagery and the LandTrendr algorithm in the Google Earth Engine platform to study and identify post-fire stages in the Great Xing’An Range of Inner Mongolia. Moreover, we categorized different post-fire vegetation recovery trajectories. The usefulness of spectral indices was also evaluated in the study region. We applied the Geodetector model to analyze the driving factors of the burned area vegetation regeneration process. The results show that burn severity and earth–atmosphere hydrological cycle are two main impacting factors in the short term after the fire (e.g. 5–6 years). Other climatical conditions affect vegetation recovery, including prolonged vegetation recovery process, hydrothermal circulation process and topographical conditions, seasonally frozen soil, freeze–thaw processes, and climate events. This study improves understanding of the dynamic successional processes in the burned area and the driving factors. Also, the outcomes can facilitate and support sustainable forest management of the Great Xing’An Range.
Shrinking gate fluorescence correlation spectroscopy yields equilibrium constants and separates photophysics from structural dynamics
Authors: Schröder Tim , Bohlen Johann , Ochmann Sarah E. , Schüler Patrick , Krause Stefan , Lamb Don C. , Tinnefeld Philip
Published: January 2023

Fluorescence correlation spectroscopy is a versatile tool for studying fast conformational changes of biomolecules especially when combined with Förster resonance energy transfer (FRET). Despite the many methods available for identifying structural dynamics in FRET experiments, the determination of the forward and backward transition rate constants and thereby also the equilibrium constant is difficult when two intensity levels are involved. Here, we combine intensity correlation analysis with fluorescence lifetime information by including only a subset of photons in the autocorrelation analysis based on their arrival time with respect to the excitation pulse (microtime). By fitting the correlation amplitude as a function of microtime gate, the transition rate constants from two fluorescence-intensity level systems and the corresponding equilibrium constants are obtained. This shrinking-gate fluorescence correlation spectroscopy (sg-FCS) approach is demonstrated using simulations and with a DNA origami-based model system in experiments on immobilized and freely diffusing molecules. We further show that sg-FCS can distinguish photophysics from dynamic intensity changes even if a dark quencher, in this case graphene, is involved. Finally, we unravel the mechanism of a FRET-based membrane charge sensor indicating the broad potential of the method. With sg-FCS, we present an algorithm that does not require prior knowledge and is therefore easily implemented when an autocorrelation analysis is carried out on time-correlated single-photon data.
Repurposing HDAC inhibitors to enhance ribonuclease 4 and 7 expression and reduce urinary tract infection
Authors: Schwartz Laura , Bochter M. Skye , Simoni Aaron , Bender Kristin , de Dios Ruiz Rosado Juan , Cotzomi-Ortega Israel , Sanchez-Zamora Yuriko I. , Becknell Brian , Linn Sarah , Li Birong , Santoro Nicholas , Eichler Tad , Spencer John David
Published: January 2023

With the emergence of antibiotic-resistant bacteria, innovative approaches are needed for the treatment of urinary tract infections. Boosting antimicrobial peptide expression may provide an alternative to antibiotics. Here, we developed reporter cell lines and performed a high-throughput screen of clinically used drugs to identify compounds that boost ribonuclease 4 and 7 expression (RNase 4 and 7), peptides that have antimicrobial activity against antibiotic-resistant uropathogens. This screen identified histone deacetylase (HDAC) inhibitors as effective RNase 4 and RNase 7 inducers. Validation studies in primary human kidney and bladder cells confirmed pan-HDAC inhibitors as well as the HDAC class I inhibitor, MS-275, induce RNase 4 and RNase 7 to protect human kidney and bladder cells from uropathogenic
Escherichia coli
. When we administered MS-275 to mice, RNase 4 and 7 expression increased and mice were protected from acute transurethral
E. coli
challenge. In support of this mechanism, MS-275 treatment increased acetylated histone H3 binding to the
RNASE4
and
RNASE7
promoters. Overexpression and knockdown of HDAC class I proteins identified HDAC3 as a primary regulator of RNase 4 and 7. These results demonstrate the protective effects of enhancing RNase 4 and RNase 7, opening the door to repurposing medications as antibiotic conserving therapeutics for urinary tract infection.
Impersonal passives in English and Norwegian
Authors: Hasselgård Hilde
Published: January 2023

This chapter investigates passive constructions with an expletive subject, labelled as impersonal passives. The English-Norwegian Parallel Corpus (ENPC) provides material for comparison across both constructions and languages. The extracted dataset shows a higher frequency of impersonal passives in Norwegian, chiefly due to two patterns that English does not have, i.e. passives with intransitive verbs and transitive verbs which retain their postverbal complement in the passive. The study considers the communicative functions of the constructions, the process types of the passivized verbs, the expression of agency, and the thematic structure of clauses with impersonal passives, finding both differences and similarities. Translations between the languages are, however, most often non-congruent, even with extraposition and parentheticals, which exist in both languages.
Towards a radically usage-based account of constructional attrition
Authors: Noël Dirk
Published: January 2023

This chapter reflects on how the gradual disappearance of a construction from a language can be accounted for in a radically usage-based diachronic construction grammar through an exploration of how the phenomenon can be accommodated in Schmid’s (2020) Entrenchment-and-Conventionalization model. This theory of the dynamics of the linguistic system is radical in its usage-based account in that it separates collective conventionalization from individual entrenchment and models how they interact in usage. Schmid focuses on the accumulative dynamics of the system, however, and gives scant attention to subtractive/attritional developments. Considering diachronic corpus data on the decline of the Deontic nci construction, the chapter brings to bear the EC-model’s conceptual apparatus to gauge the role of individual speakers in language-level constructional attrition.
The compound pronouns someone/somebody and everyone/everybody in present-day spoken English
Authors: Butler Christopher S. , Simon-Vandenbergen Anne-Marie
Published: January 2023

This article builds on previous research on the compound pronoun sets somebody/someone and everybody/everyone to test the hypotheses that the -one and -body forms are semantically identical, but that stylistic and social factors play a role in their relative frequencies. Earlier findings are checked in informal conversation in the Spoken BNC2014. The distribution of the variants is examined in correlation with sociolinguistic parameters, and collocational profiles of the pronouns are compared to test free variation. Our data show further ongoing change towards dominance of the -one forms. Only age significantly affects both pronoun pairs, with a minor effect of gender for the every- pair. Collocation analysis shows significant differences between some- and every- but not between -one and -body.
Iconicity in spatial deixis
Authors: Breunesse Merlijn , Diessel Holger
Published: January 2023

This paper presents a cross-linguistic analysis of iconicity in demonstrative systems. Several previous studies have observed that the stem vowels of demonstratives correlate with the encoding of distance (e.g. Woodworth 1991). Nevertheless, there is little systematic research on iconicity in spatial deixis (but see Johansson & Zlatev 2013). Analyzing data from a sample of 180 languages, we argue that iconicity in demonstrative systems is a multifaceted phenomenon. In addition to demonstratives’ vowels, there are several other formal aspects of demonstratives that are arguably iconic, i.e. tone, vowel lengthening, reduplication, and word length. These results corroborate a growing body of research that emphasizes the importance of iconic motivations for the encoding of meaning and raise new questions for future research.