bluuebunny/crossref_metadata_2025 huggingface dataset:
Probing electrical properties of a silicon nanocrystal thin film using x-ray photoelectron spectroscopy
Authors: Laudari Amrit , Pathiranage Sameera , Thomas Salim A. , Petersen Reed J. , Anderson Kenneth J. , Pringle Todd A. , Hobbie Erik K. , Oncel Nuri
Published: August 2022

We performed x-ray photoelectron spectroscopy measurements on a thin film of Si nanocrystals (SiNCs) while applying DC or AC external biases to extract the resistance and the capacitance of the thin film. The measurement consists of the application of 10 V DC or square wave pulses of 10 V amplitude to the sample at various frequencies ranging from 0.01 to 1 MHz while recording x-ray photoemission data. To analyze the data, we propose three different models with varying degrees of accuracy. The calculated capacitance of SiNCs agrees with the experimental value in the literature.
Multi-pass cell spectral broadening at high pulse energies
Authors: Tavella F. , Mecseki K.
Published: August 2022

We simulate experimental conditions for nonlinear spectral broadening and compression of multi-joule, sub-picosecond, and femtosecond laser systems focusing on 1 μm center wavelength. The spatial, spectral, and temporal properties of two distinct cases are investigated in detail. The first system is a short multi-pass cell with 0.1–0.5 J pulse energy operated at higher helium pressures, used to illustrate the transition between Kerr-effect induced spectral broadening and spectral broadening in plasma. The second case is a long ten-joule multi-pass cell operated at few Pascal pressure range. These examples cover the operational extent of plasma spectral broadening in a multi-pass cell. Effects pertaining to plasma spectral broadening, including imperfect spatial beam profiles and initial non-zero nonlinear phase, are investigated, as well as scalability.
Progressive approximation of bound states by finite series of square-integrable functions
Authors: Alhaidari A. D.
Published: August 2022

We use the “tridiagonal representation approach” to solve the time-independent Schrödinger equation for bound states in a basis set of finite size. We obtain two classes of solutions written as a finite series of square integrable functions that support a tridiagonal matrix representation of the wave operator. The differential wave equation becomes an algebraic three-term recursion relation for the expansion coefficients of the series, which is solved in terms of finite polynomials in the energy and/or potential parameters. These orthogonal polynomials contain all physical information about the system. The basis elements in configuration space are written in terms of either the Romanovski–Bessel polynomial or the Romanovski–Jacobi polynomial. The maximum degree of both polynomials is limited by the polynomial parameter(s). This makes the size of the basis set finite but sufficient to give a very good approximation of the bound state wavefunctions that improves with an increase in the basis size.
Hand-held free-scan 3D photoacoustic tomography with global positioning system
Authors: Jiang Daohuai , Chen Hongbo , Zheng Rui , Gao Fei
Published: August 2022

As an emerging medical diagnostic technology, photoacoustic imaging has been implemented for both preclinical and clinical applications. For clinical convenience, a handheld free-scan photoacoustic tomography (PAT) system providing 3D imaging capability is essentially needed, which has potential for surgical navigation and disease diagnosis. In this paper, we proposed a free-scan 3D PAT (fsPAT) system based on a handheld linear-array ultrasound probe. A global positioning system (GPS) is applied for ultrasound probe's coordinate acquisition. The proposed fsPAT can simultaneously realize real-time 2D imaging and large field-of-view 3D volumetric imaging, which is reconstructed from the multiple 2D images with coordinate information acquired by the GPS. To form a high-quality 3D image, a dedicated space transformation method and a reconstruction algorithm are used and validated by the proposed system. Both simulation and experimental studies have been performed to prove the feasibility of the proposed fsPAT. To explore its clinical potential, in vivo 3D imaging of human wrist vessels is also conducted, showing a clear subcutaneous vessel network with high image contrast.
A topological realization of spin polarization through vortex formation in collisions of Bose–Einstein condensates
Authors: Deng Jian , Wang Qun , Zhang Hong
Published: August 2022

The global spin polarization of hadrons in heavy ion collisions has been measured in the solenoidal tracker at relativistic heavy ion collider experiments, which opens up a new window in the study of the hottest, least viscous, and most vortical fluid that has ever been produced in the laboratory. We present a different approach to spin polarization from conventional ones: a topological realization of spin polarization through quantum vortex formation in collisions of Bose–Einstein condensates. This approach is based on the observation that the vortex is a topological excitation in a superfluid in the presence of local orbital angular momentum and is an analog of spin degrees of freedom. The formation processes of vortices and vortex–antivortex pairs are investigated by solving the Gross–Pitaevskii equation with a large-scale parallel algorithm on a graphics processing unit to very high precision. In a rotating environment, the primary vortex with winding number one is stable against perturbation, which has minimal energy and fixed orbital angular momentum (OAM), but the vortices with larger winding numbers are unstable and will decay into primary vortices through a redistribution of the energy and vorticity. The injection of OAM can also be realized in non-central collisions of self-interacting condensates, part of the OAM of the initial state will induce the formation of vortices through concentration of energy and vorticity density around topological defects. Different from a hydrodynamical description, the interference of the wave function plays an important role in the transport of energy and vorticity, reflecting the quantum nature of the vortex formation process. The study of the vortex formation may shed light on the nature of particle spin and spin–orbit couplings in strong interaction matter produced in heavy-ion collisions.
Enhanced extremely weak-field energy harvesting via magnetic flux and stress concentration effects in ferromagnetic/ferroelectric composite
Authors: Yu Zhonghui , Li Zhanmiao , Yuan Xiaoting , Asl Mohammad Javad Pourhosseini , Dong Shuxiang
Published: August 2022

In this work, we report an enhanced magneto-mechano-electric (MME) coupling in Ni/Pb(Zr,Ti)O3 (PZT) ceramic composited ladder-type cantilever attached with a tip mass of NdFeB magnet, which simultaneously exhibits the magnetic flux concentration effect and the stress concentration effect, and therefore, it shows an enhanced extremely weak-field (EWF) coupling ability. Investigations show that the proposed MME energy harvester (EH) can generate an output power density of 7.16 μW Hz−1 Oe−2 cm−3, which is the highest value compared to the state of the art MME energy harvesters. Under an EWF of even as low as Hac = 0.1 Oe (about half level of the geomagnetic field), the proposed MME-EH can still produce a peak–peak output power of 23.5 μW, which is enough power to light up 4 LEDs in real time. Furthermore, it can drive a wireless sensor communication system in real time under a weak Hac = 0.75 Oe excitation, demonstrating it has potential to serve as a micro-energy source of wireless sensor networks in EWF circumstance. This work is not only beneficial but has also inspired future multi-function-integrated material and smart electronic device designs in Internet of Things in EWF circumstance.
Influence of chemical disorder on mechanical and thermal properties of multi-component rare earth zirconate pyrochlores (nRE1/n)2Zr2O7
Authors: Li Yiran , Wu Qi , Lai Mengling , Zhao Juanli , Liu Yuchen , Fan Yun , Yao Yun , Liu Bin
Published: August 2022

To explore the underlying mechanism of chemical disorder in high-entropy pyrochlores, ten rare earth zirconates (nRE1/n)2Zr2O7 (n = 1, 2, and 4, RE = La, Nb, Sm, Eu, and Gd) are studied by using first-principles calculations. The mechanical and thermal properties are carefully analyzed with a special focus on local structural evolution and interatomic interaction. It is found that all three kinds of bond lengths increase linearly with lattice parameters whether the pyrochlore involves chemical disorder or not. Compared with the single-component counterparts, the multi-component pyrochlores are recognized to exhibit higher elastic constants and moduli but lower elastic anisotropy. Meanwhile, (LaSmEuGd)2Zr2O7 shows the lowest thermal conductivity, which can be attributed to the larger La atoms and the weaker La–O bonding. Furthermore, the abnormal strengthening of phonon anharmonicity in (SmEu)2Zr2O7 emphasizes the significance of fluctuation in local distortion rather than enhancement in chemical disorder on decreasing thermal conductivity for high-entropy ceramics. This work uncovers the physical origins of the chemical disorder effect on mechanical and thermal properties for pyrochlores and further shed some lights on the design of high-performance high-entropy ceramics with great potential applications including thermal barrier coatings.
Understanding synaptic characteristics of nonvolatile analog redox transistor based on mobile ion-modulated-electrolyte thickness model for neuromorphic applications
Authors: Kim Nayeon , Kang Heebum , Kim Hyun Wook , Hong Eunryeong , Woo Jiyong
Published: August 2022

Linear and symmetric updates of the channel current of the redox transistor are involved in bulk mobile ion motion. In this study, we introduce the concept of a variable effective electrolyte thickness (teff) precisely tuned by gate voltage-driven ions into the drain current equation of a conventional transistor. In order to understand the switching characteristics of a nonvolatile analog redox transistor that serves as an artificial synapse for neuromorphic systems, we developed a physics-based model in MATLAB. The simulated synaptic update curves obtained using identical gate pulses were in good agreement with the fabricated Cu-ion-actuated CuOx/HfOx/WOx redox transistor. We then analyzed the impact of geometrical and material-related parameters on the synaptic behavior, taking into account the ion speed and the degree of allowable electric field through the electrolyte. In addition, we performed Monte Carlo simulation to create a non-uniformly changed teff circumstance. With this, we reproduced the fluctuated update of the channel current every gate pulse, which is occasionally observed experimentally when mobile ions are easily moved randomly. Our simulation results revealed that the redox transistor immune to the unevenly changed teff can be achieved by lowering the ion velocity.
All-organic flexible heterojunction thin film photodetectors based on phthalocyanines/C60
Authors: Zhang Xiaoqiang , Gao Huiying , Yang Ming , Jiang Hao , Li Zhoushuo
Published: August 2022

In modern organic photoelectric detection, a broad spectrum response is much needed. Unfortunately, it remains a huge challenge in the field of optoelectronics. In this work, a photodetector based on phthalocyanines/C60 thin film heterojunction was fabricated by in situ secondary evaporation. Most encouragingly, the device has no selectivity to the substrate and can grow well on the flexible substrate, and the performance of the device changes merely 7.27% after 104 bending cycles, which shows its stability performance. The device has the ability to detect a wide band from visible light to near infrared. The largest Ri of the device was obtained reaching up to 0.94 A W−1, with crest value D* equals to 4.7 × 1012 Jones. The all-organic heterojunction devices prepared by us have the advantages of simple preparation method, low cost, and no selectivity to the substrate, which shows a very good application potential in the fields of flexible wearable and infrared remote sensing imaging in the future.
On the conduction mechanism in compositionally graded AlGaN
Authors: Rathkanthiwar Shashwat , Bagheri Pegah , Khachariya Dolar , Kim Ji Hyun , Kajikawa Yasutomo , Reddy Pramod , Mita Seiji , Kirste Ronny , Moody Baxter , Collazo Ramon , Sitar Zlatko
Published: August 2022

A two-band transport model is proposed to explain electrical conduction in graded aluminum gallium nitride layers, where the free hole conduction in the valence band is favored at high temperatures and hopping conduction in the impurity band dominates at low temperatures. The model simultaneously explains the significantly lowered activation energy for p-type conduction (∼10 meV), a nearly constant sheet conductivity at lower temperatures (200–330 K), and the anomalous reversal of the Hall coefficient caused by the negative sign of the Hall scattering factor in the hopping conduction process. A comparison between the uniform and graded samples suggests that compositional grading significantly enhances the probability of phonon-assisted hopping transitions between the Mg atoms.
Quantifying energetic information in density functional theory
Authors: Liu Shubin
Published: August 2022

Energy and information are two fundamental concepts in physics and chemistry. In density functional theory (DFT), all information pertaining to stability, reactivity, and other properties is encompassed in the ground state electron density. The basic theorems of DFT govern that energy is a universal functional of the density, and thus, it can be regarded as a special kind of information. In this work, we quantify the energetic information in terms of Shannon entropy and Fisher information for energetic distributions of atoms and molecules. Two identities are unveiled for an energetic density, its gradient, and Laplacian to rigorously satisfy. A new partition scheme to decompose atoms in molecules has been proposed using the energetic distribution. We also show that our approach can simultaneously quantify both two-body and many-body interactions. This new framework should provide new analytical tools for us to appreciate electronic properties of molecular systems, including stability and reactivity. More importantly, this work establishes the missing link in DFT between energy and information, the two most fundamental quantities in quantum theory.
Theoretical investigation of rotationally inelastic collisions of OH(X2Π) with hydrogen atoms
Authors: Dagdigian Paul J.
Published: August 2022

State-to-state cross sections and rate coefficients for transitions between rotational/fine-structure levels of OH(X2Π) induced by collisions with atomic hydrogen are reported in this work. The scattering calculations take into account the full open-shell character of the OH + H system and include the four potential energy surfaces (1A′, 1A″, 3A′, 3A″) that correlate with the OH(X2Π) + H(2S) asymptote. Three of these surfaces are repulsive, while the deep H2O well is present on one surface (1A′). The OH + H potential energy curves calculated by Alexander et al. [J. Chem. Phys. 121, 5221 (2004)] are employed in this work. Time independent quantum scattering calculations were performed using the quantum statistical method of Rackham and co-workers [Chem. Phys. Lett. 343, 356 (2001)] because of the presence of the deep H2O well. The computed cross sections include contributions from direct scattering, as well formation and decay of a transient collision complex since the transient HO–H complex is expected to decay nonreactively. Rate coefficients for OH–H inelastic collisions are of interest for astrophysical applications.
Using microchip-reading antennas to passively monitor a mammal reintroduction in south-west Queensland
Authors: Arkinstall Cassandra M. , FitzGibbon Sean I. , Bradley Kevin J. , Moseby Katherine E. , Murray Peter J.
Published: August 2022

Microchip-reading devices provide an inexpensive and efficient means of passively detecting and monitoring wildlife reintroductions, particularly where intensive methods such as trapping and radio-tracking may be difficult or pose risk to animal welfare. We trialled the use of microchip-reading antennas for post-release monitoring of the survival of bilbies (Macrotis lagotis) for a reintroduction in south-west Queensland. The antennas detected 76% of the released captive-born bilbies (all microchipped) and 30% of the microchipped wild-born bilbies during the study period. Overall, the microchip-reading antennas greatly improved the rate of detection for bilbies in the enclosure compared to cage trapping alone. Of the 42 bilbies that were microchipped and had the potential to be recaptured in traps or detected on microchip readers, 33 were recorded from the combined approaches, with 20 bilbies recaptured in traps and 29 bilbies detected on the microchip readers. Antenna location/placement should be carefully considered in the context of the target species’ home range size as it may affect the probability of animals encountering the antenna. Here we demonstrate the ability to use these microchip-reading antennas to passively monitor post-release survival in a remote location, just one of many potential applications for these devices in wildlife management and conservation.
Development and patent synthesis of nirmatrelvir – the main component of the first oral drug against SARS-CoV-2 Paxlovid
Authors: Cotrim Bruno A. , Barros José C.
Published: August 2022

Nirmatrelvir is the main component of the first oral drug against SARS-CoV-2 called Paxlovid®. Its development from an orally unavailable predecessor through hydrogen bond donors (HBD) replacement is highlighted, followed by an examination of the synthetic routes described in the original PCT application WO2021/250648. Based on its attributes, nirmatrelvir shows the potential to be a game changer in SARS-CoV-2 treatment.
Neural synchronization predicts marital satisfaction
Authors: Li Lei , Huang Xinyue , Xiao Jinming , Zheng Qingyu , Shan Xiaolong , He Changchun , Liao Wei , Chen Huafu , Menon Vinod , Duan Xujun
Published: August 2022

Marital attachment plays an important role in maintaining intimate personal relationships and sustaining psychological well-being. Mate-selection theories suggest that people are more likely to marry someone with a similar personality and social status, yet evidence for the association between personality-based couple similarity measures and marital satisfaction has been inconsistent. A more direct and useful approach for understanding fundamental processes underlying marital satisfaction is to probe similarity of dynamic brain responses to maritally and socially relevant communicative cues, which may better reflect how married couples process information in real time and make sense of their mates and themselves. Here, we investigate shared neural representations based on intersubject synchronization (ISS) of brain responses during free viewing of marital life-related, and nonmarital, object-related movies. Compared to randomly selected pairs of couples, married couples showed significantly higher levels of ISS during viewing of marital movies and ISS between married couples predicted higher levels of marital satisfaction. ISS in the default mode network emerged as a strong predictor of marital satisfaction and canonical correlation analysis revealed a specific relation between ISS in this network and shared communication and egalitarian components of martial satisfaction. Our findings demonstrate that brain similarities that reflect real-time mental responses to subjective perceptions, thoughts, and feelings about interpersonal and social interactions are strong predictors of marital satisfaction, reflecting shared values and beliefs. Our study advances foundational knowledge of the neurobiological basis of human pair bonding.
Subpetahertz helicity modulation of attosecond pulse train using detuned two-color fields
Authors: Sun Ning , Chen Yuantong , Chen Yuhang , Zhu Xiaosong
Published: August 2022

We theoretically demonstrate a scheme to obtain an attosecond pulse train with subpetahertz helicity modulation, based on high harmonic generation driven by detuned two-color fields. As the waveform of the detuned two-color field varies with time, the attosecond pulse train switches periodically between left and right elliptical polarization in the temporal domain. The frequency of the helicity modulation can reach subpetahertz. In addition, by adjusting the frequency detuning of the two-color field, the modulation frequency can be continuously controlled. The scheme is expected to provide a useful light source to explore and manipulate a wide range of ultrafast dynamics in magnetic materials and chiral molecules.
Fault diagnosis of bearings in multiple working conditions based on adaptive time-varying parameters short-time Fourier synchronous squeeze transform
Authors: Wei Minghui , Yang Jianwei , Yao Dechen , Wang Jinhai , Hu Zhongshuo
Published: August 2022

Rolling bearings are commonly used components in rotating machinery and play a vital role. When the bearing fails, if it cannot be found and repaired in time, it will cause great economic losses. Time-frequency analysis has been widely used for bearing fault signals under non-stationary operating conditions, but the existing methods have problems such as poor adaptability under multiple operating conditions. At the same time, the low time-frequency resolution and poor energy aggregation also affect the fault feature extraction effect. Aiming at these problems, this paper proposes a bearing fault detection method, which combines empirical mode decomposition and adaptive time-varying parameter short-time Fourier synchronous squeezing transform (AFSST), it solves the problem of adapting to signals under multiple operating conditions; A weighted least squares estimation time-varying parameter algorithm is proposed, which improves the calculation speed by 29% under the premise of ensuring the calculation accuracy; A time-varying index of energy effective compression ratio is proposed to accurately measure the time-varying energy aggregation of time-frequency analysis methods. Using short-time Fourier transform, continuous wavelet transform, wavelet synchrosqueezed transform, and AFSST to analyze the simulated FM signal, the results show that the AFSST transform has better time-frequency resolution and higher energy-efficient compression rate globally. Through the verification of the fault experimental data of rolling bearings, the diagnosis method proposed in this paper can accurately extract the bearing fault characteristics, has a good diagnosis ability in the multi-working operating environment, and has strong robustness and anti-noise interference.
Sub-wavelength focusing for low-frequency sound sources using an iterative time reversal method
Authors: Li Yuanwen , Li Min , Pan Wei , Feng Daofang , Yang Debin
Published: August 2022

Microphone array measurements processed with imaging algorithms are commonly performed to identify and quantify noise sources in machines, which is the premise of noise control. However, due to the limitations of the half-wavelength theory, beamforming and time reversal (TR) methods cannot effectively separate multiple low-frequency sources. Although near-field acoustic holography can overcome the diffraction limit, it will encounter an ill-posed problem. To avoid solving the inverse problem, iterative TR processing (iterative-TR) is proposed to obtain the sub-wavelength focusing and improve the spatial resolution at low frequency. The focusing result is corrected step by step with iteration implemented until it reaches the convergence threshold. The propagation matrix between microphones and focusing points is reconstructed by singular-value normalization to ensure the convergence of the iteration. Numerical simulation results show that the iterative-TR method is able to break through the diffraction limit below 1000 Hz within a measurement distance of 0.5 m and reach convergence within 105 iterations, which is less than 10 s. The experimental results indoors with significant reverberation show that iterative-TR has the ability to stably give the multiple source positions with 0.11 m spacing even at 100 Hz, that is, the spatial resolution reaches 1/31 wavelength. Detailed analysis shows that the overall performance of iterative-TR outperforms other methods capable of sub-wavelength focusing for signals below 1000 Hz. The identification of two loudspeakers in a car shows the practicality of the proposed method.
An exploratory study of machine learning techniques applied to therapeutic energies particle tracking in microdosimetry using the novel hybrid detector for microdosimetry (HDM)
Authors: Missiaggia Marta , Pierobon Enrico , La Tessa Chiara , Cordoni Francesco G
Published: August 2022

In this work we present an advanced random forest-based machine learning (ML) model, trained and tested on Geant4 simulations. The developed ML model is designed to improve the performance of the hybrid detector for microdosimetry (HDM), a novel hybrid detector recently introduced to augment the microdosimetric information with the track length of particles traversing the microdosimeter. The present work leads to the following improvements of HDM: (i) the detection efficiency is increased up to 100%, filling not detected particles due to scattering within the tracker or non-active regions, (ii) the track reconstruction algorithm precision. Thanks to the ML models, we were able to reconstruct the microdosimetric spectra of both protons and carbon ions at therapeutic energies, predicting the real track length for every particle detected by the microdosimeter. The ML model results have been extensively studied, focusing on non-accurate predictions of the real track lengths. Such analysis has been used to identify HDM limitations and to understand possible future improvements of both the detector and the ML models.
Development of controller for fast plasma position control coils with ISO-FLUX scheme on JT-60SA
Authors: Kojima S , Inoue S , Miyata Y , Urano H , Suzuki T
Published: August 2022

Two types of poloidal magnetic field coils, superconducting poloidal field (SCPF) coils and in-vessel coils called fast plasma position control (FPPC) coils, will be installed in JT-60SA. We presented the different roles of SCPF and FPPC coils. The SCPF coils control plasma position and shape (P/S) and plasma current (I
p), whereas the FPPC coils stabilize the perturbation of the n= 0 mode of magnetohydrodynamic (MHD) instability, such as vertical instability. This study developed a controller that outputs a coil voltage command for the power supply connected to each coil based on an ISO-FLUX scheme using an equilibrium control simulation code, MHD equilibrium control simulator (MECS). This controller stabilizes the horizontal and vertical plasma displacements using FPPC coils. FPPC coils have the advantage of FPPC due to fast coil current response; however, the induced current is also driven in FPPC coils. Thus, we proposed a control logic to mitigate the induced currents, particularly when the induced voltage is large. The difference in coil current response for SCPF and FPPC coils causes the coupling problem. Thus, decoupling between the SCPF and FPPC coils was established by employing the derivative treatment on the ISO-FLUX scheme in the FPPC control. To investigate the effectiveness of the FPPC control, using MECS we evaluated the allowable I
p disruption intensity, which causes the plasma horizontal displacement, in the high elongation plasma, which relates to the plasma vertical displacement. Higher I
p disruption intensity and elongation were allowed by adding the FPPC control. We investigated the controllability in the plasma ramp-up and flat-top operations. The support of FPPC control for SCPF control expands the plasma operation region which contributes to achieving the planned plasma operation in JT-60SA.
Application of deep learning to soft x-ray tomography at EAST
Authors: Mai Chaowei , Hu Liqun , Xu Liqing , Chao Yan , Chen Kaiyun , Chen Yiping
Published: August 2022

Soft x-ray (SXR) cameras in a tokamak are limited spatially by ports of the vacuum vessel, and SXR tomography (SXT) technology is developed for reconstructing a two-dimensional SXR profile. However, traditional SXT is time-consuming and has difficulty achieving abundant and quick reconstructions for a tokamak. Based on experimental SXR data and Fourier–Bessel SXT codes at the EAST tokamak, three typical neural networks are built and trained. All the trained neural networks complete reconstruction within several milliseconds on a personal computer and succeed in constraining the SXR profile to match most of the data. In particular, the best-performing fully convolutional neural network provides SXR reconstruction images on the 2D evolution of a sawtooth, and shows its generalization. In the future, it is possible to provide an outstanding deep learning substitute to give abundant and quick SXT images instead of traditional SXT, after training for a few days.
Nonlocal Timoshenko shear beam model for multilayer curved graphene nano-switches
Authors: Koochi Ali , Yaghoobi Majid
Published: August 2022

Graphene sheets are the basis of nano-electromechanical switches, which offer a unique insight into the world of quantum mechanics. In this paper, we proposed a new size-dependent multi-beam shear model for investigating the pull-in instability of multilayer graphene/substrate nano-switches within the context of the Timoshenko beam theory. As the graphene/substrate bemas bent toward the graphene layer due to the thermomechanical mismatch, the impact of curvature is considered in the proposed model. Also, the impact of the Casimir attraction is incorporated in the developed model by taking into account the limited conductivity of interacting surfaces. The scale dependency of the materials is considered in the framework of the nonlocal elasticity. To simulate the nano-switch and explore the pull-in instability, a finite element procedure is developed. The proposed approach is verified by comparing the pull-in voltage to published data. Finally, the role of influential parameters, including size dependency, length, initial gap, curvature, and the number of graphene layers on instability voltage of nano-switch, are investigated.
Self-interacting dark scalar spikes around black holes via relativistic Bondi accretion
Authors: Feng Wei-Xiang , Parisi Alessandro , Chen Chian-Shu , Lin Feng-Li
Published: August 2022

We consider the spike mass density profile in a dark halo by self-consistently solving the relativistic Bondi accretion of dark matter onto a non-spining black hole of mass M. We assume that the dominant component of the dark matter in the halo is a Standard model gauge-singlet scalar. Its mass m ≃ 10-5 eV and quartic self-coupling λ ≲ 1019 are constrained to be compatible with the properties of galactic dark halos. In the hydrodynamic limit, we find that the accretion rate is bounded from below, M
min = 96πG
2
M
2
m
4/λħ
3. Therefore, for M = 106
M⊙ we have M
min ≃ 1.41 × 10-9
M
⊙ yr-1, which is subdominant compared to the Eddington accretion of baryons. The spike density profile ρ
0(r) within the self-gravitating regime cannot be fitted well by a single-power law but a double-power one. Despite that, we can fit ρ
0(r) piecewise and find that ρ
0(r) ∝ r
-1.20 near the sound horizon, ρ
0(r) ∝ r
-1.00 towards the Bondi radius and ρ
0(r) ∝ r
-1.08 for the region in between. This contrasts with more cuspy ρ
0(r) ∝ r
-1.75 for dark matter with Coulomb-like self-interaction.
Variational quantum eigensolvers by variance minimization
Authors: Zhang Dan-Bo , Chen Bin-Lin , Yuan Zhan-Hao , Yin Tao
Published: August 2022

The original variational quantum eigensolver (VQE) typically minimizes energy with hybrid quantum-classical optimization that aims to find the ground state. Here, we propose a VQE based on minimizing energy variance and call it the variance-VQE, which treats the ground state and excited states on the same footing, since an arbitrary eigenstate for a Hamiltonian should have zero energy variance. We demonstrate the properties of the variance-VQE for solving a set of excited states in quantum chemistry problems. Remarkably, we show that optimization of a combination of energy and variance may be more efficient to find low-energy excited states than those of minimizing energy or variance alone. We further reveal that the optimization can be boosted with stochastic gradient descent by Hamiltonian sampling, which uses only a few terms of the Hamiltonian and thus significantly reduces the quantum resource for evaluating variance and its gradients.
Dramatic reduction in dark current of β-Ga2O3 ultraviolet photodectors via β-(Al0.25Ga0.75)2O3 surface passivation
Authors: Yue Jian-Ying , Ji Xue-Qiang , Li Shan , Qi Xiao-Hui , Li Pei-Gang , Wu Zhen-Ping , Tang Wei-Hua
Published: August 2022

Solar-blind ultraviolet photodetectors with metal-semiconductor-metal structure were fabricated based on β-(Al0.25Ga0.75)x2O3/β-Ga2O3 film grown by metal-organic chemical vapor deposition. It was known that various surface states increase dark current and a large number of defects can hinder the transport of carriers, resulting in low switching ratio and low responsivity of the device. In this work, β-(Al0.25Ga0.75)2O3 films are used as surface passivation materials. Owning to its wide band gap, we obtain excellent light transmission and high lattice matching with β-Ga2O3. We explore the change and mechanism of the detection performance of the β-Ga2O3 detector after β-(Al0.25Ga0.75)2O3 surface passivation. It is found that under the illumination with 254 nm light at bias 5 V, the β-(Al0.25Ga0.75)2O3/β-Ga2O3 photodetectors show dark current of just 18 pA and high current on/off ratio of 2.16 × 105. The dark current is sharply reduced about 50 times after passivation of the β-Ga2O3 surface, and current on/off ratio increases by approximately 2 times. It is obvious that β-Ga2O3 detectors with β-(Al0.25Ga0.75)2O3 surface passivation can offer superior detector performance.
Simulations of charge collection of a gallium nitride based pin thin-film neutron detector
Authors: Zhang Z. , Aspinall M.
Published: August 2022

The development of new fast neutron reactors and nuclear fusion reactors requires new neutron detectors in extreme environments. Due to its wide bandgap (3.4 eV) and radiation resistance capability, gallium nitride (GaN) is a candidate for neutron detection in extreme environments. This study introduces a novel simulation method of charge collection efficiency (CCE) for GaN pin thin-film neutron detector based on the Hecht equation and Monte Carlo simulation. A modified 2-carrier Hecht equation is used to simulate the CCE of the detector with a different depth depletion region. After obtaining the neutron energy deposition distribution in the sensitive volume of the detector, the Hecht equation is used to calculate the charge collection efficiency at different positions of the detector under a uniform electric field. The maximum relative error between the simulated CCE and the experimental CCE value is about 6.3%.
Committed to restoring tropical forests: an overview of Brazil’s and Indonesia’s restoration targets and policies
Authors: Dockendorff Constantino , Fuss Sabine , Agra Raquel , Guye Valentin , Herrera Diego , Kraxner Florian
Published: August 2022

The restoration of tropical forests has become a popular nature-based solution for climate change mitigation, protection of biodiversity, and improving the livelihoods of local populations. The Bonn Challenge and the UN Decade on Ecosystem Restoration underscore the international momentum of the restoration movement, with many countries committing to restore millions of hectares of deforested and degraded land in the next decade. Brazil and Indonesia are among the ones with the most ambitious restoration commitments globally. Since both their economies are highly dependent on the export of agricultural commodities, reconciling economic growth with environmental sustainability will be a major policy challenge. In this paper, we (a) identify the main restoration targets and the policies supporting their implementation in both countries, (b) provide a descriptive overview of these restoration-supportive policies, and (c) discuss the main challenges that Brazil and Indonesia face in the implementation of their restoration commitments. We find that Brazil has an explicit and dedicated strategy to achieve its restoration target, but that recent political developments have weakened environmental governance in the country, affecting the implementation of its restoration commitment. In the case of Indonesia, we find that the government has rather focused and progressed on the restoration of peatlands and mangroves, whereas its commitment to restore forestlands has yet to benefit from a dedicated plan that allows to coordinate policies and agencies’ efforts towards the achievement of its restoration target.
VASP localization to lipid bilayers induces polymerization driven actin bundle formation
Authors: Nast-Kolb T. , Bleicher P. , Payr M. , Bausch A. R.
Published: August 2022

Contrary to conventional actin cross-linkers, we show that vasodilator-stimulated phosphoprotein (VASP) bound to lipid bilayers in vitro facilitates the formation of actin bundles through alignment by polymerization. The mobility enables VASP to phase separate and track growing barbed ends while accumulating on the actin bundles. This in turn results in a reorganization of the bilayer.
Docking of Syk to FcεRI is enhanced by Lyn but limited in duration by SHIP1
Authors: Kanagy William K. , Cleyrat Cédric , Fazel Mohamadreza , Lucero Shayna R. , Bruchez Marcel P. , Lidke Keith A. , Wilson Bridget S. , Lidke Diane S.
Published: August 2022

Kanagy et al. combine biochemical and fluorescence microscopy methods to determine the interplay between positive and negative signaling molecules within the FcεRI signalosome. The results highlight the ability of ITAM-based signaling to respond to various ITAM phosphorylation patterns, Syk binding conformations, and the presence/absence of key regulatory molecules. These molecular mechanisms provide insight into how disparate immunoreceptors can utilize conserved signaling cascades to tailor their cellular outcomes.
DhMYB22andDhMYB60regulate pigment intensity and floral organ shape inDendrobiumhybrid
Authors: Khairul-Anuar Muhammad-Asyraf , Mazumdar Purabi , Othman Rofina Yasmin , Harikrishna Jennifer Ann
Published: August 2022

Background

Flower pigment and shape are determined by the coordinated expression of a set of structural genes during flower development. R2R3-MYB transcription factors are known regulators of structural gene expression. The current study focused on two members of this large family of transcription factors that were predicted to have roles in pigment biosynthesis and organ shape development in orchids.

Methods

Phylogenetic analysis was used to identify candidate Dendrobium catenatum R2R3-MYB (DcaMYB) sequences associated with pigment and cell shape development. Gene silencing of candidate DhMYBs in Dendrobium hybrid by direct application of dsRNA to developing flowers was followed by observation of gene expression level and flower phenotypes. Silencing of the structural gene chalcone synthase was used as a comparative control.

Key Results

Ten candidate flower-associated DcaMYBs were identified. Flowers treated with dsRNA of DhMYB22 and DhMYB60 sequences were less pigmented and had relatively low expression of anthocyanin biosynthetic genes (F3ʹH and DFR), lower total anthocyanin concentration and markedly lower levels of cyanidin-3-glucoside and cyanidin-3-rutinoside. Petals of DhMYB22-treated flowers and sepals of DhMYB60-treated flowers showed the greatest colour difference relative to the same organs in untreated flowers. DhMYB22-treated flowers had relatively narrow and constricted lips, while DhMYB60-treated flowers had narrow and constricted sepals. No significant difference in shape was observed for DhCHS-treated or untreated flowers.

Conclusions

Our results demonstrate that DhMYB22 and DhMYB60 regulate pigment intensity and floral organ shape in Dendrobium. This is a first report of MYB regulation of floral organ shape in orchids.
Phylogeography of the mesic-adapted striped mouse,Rhabdomys dilectus chakae(Rodentia: Muridae) in forest margins of the Eastern Cape and southern KwaZulu-Natal provinces of South Africa
Authors: Matamba Emmanuel , Richards Leigh R , Cherry Michael I , Rambau Ramugondo V
Published: August 2022

Rhabdomys is a genus that occupies a variety of habitats, including forest margins. Among the Rhabdomys taxa, Rhabdomys dilectus chakae has a distribution that covers the eastern seaboard of South Africa, with a poorly defined divergence date from its sister taxon Rhabdomys dilectus dilectus. Here, we study three mitochondrial markers (cytochrome b, cytochrome c oxidase I and partial control region) of R. d. chakae across the Eastern Cape and KwaZulu-Natal forests of South Africa, aiming to determine the cladogenesis (molecular dating) and effective population size of this subspecies through time, in addition to its cladogenesis in relationship to other species within the genus. A phylogenetic analysis revealed six clades within Rhabdomys, confirming that our study area is occupied solely by R. d. chakae, to the exclusion of other recognized sibling species. A fossil-calibrated Bayesian relaxed molecular clock estimated a recent split between R. d. chakae and R. d. dilectus ~1.4 ± 0.35 Mya and between two Rhabdomys pumilio groups, coastal A and B, at 1.16 ± 0.44 Mya. Coalescent Bayesian skyline plots revealed a stable population of R. d. chakae in the study area that was in slow decline until 2500 years ago, when there was an expansion in the late Holocene. Radiation within Rhabdomys dates as far back as 4.27 Mya, and subsequent demographic fluctuations primarily reflect palaeoclimatic changes.
Investigation of the optimal culture time for warmed bovine ovarian tissues before transplantation
Authors: Meng Lingbo , Sugishita Yodo , Nishimura Sandy , Uekawa Atsushi , Suzuki-Takahashi Yuki , Suzuki Nao
Published: August 2022

Ovarian tissue cryopreservation by vitrification is an effective technique, but there are still many unresolved issues related to the procedure. The aim of this study was to investigate the optimal culture time of postwarmed ovarian tissues and their viability before ovarian tissue transplantation. The bovine ovarian tissues were used to evaluate the effect of postwarming culture periods (0, 0.25, 0.5, 1, 2, 5, and 24 h) in the levels of residual cryoprotectant, LDH release, ROS generation, gene and protein abundance, and follicle viability and its mitochondrial membrane potential. Residual cryoprotectant concentration decreased significantly after 1 h of culture. The warmed ovarian tissues that underwent between 0 and 2 h of culture time showed similar LDH and ROS levels compared with fresh nonfrozen tissues. The anti-Mullerian hormone transcript abundance did not differ in any of the groups. No increase in the relative transcript abundance and protein level of Caspase 3 and Cleaved-Caspase 3, respectively, in the first 2 h of culture after warming. On the other hand, an increased protein level of double stranded DNA breaks (gamma-H2AX) was observed in postwarmed tissues disregarding the length of culture time, and a temporary reduction in pan-AKT was detected in postwarming tissues between 0 and 0.25 h of culture time. Prolonged culture time lowered the percentage of viable follicles in warmed tissues, but it did not seem to affect the follicular mitochondrial membrane potential. In conclusion, 1–2 h of culture time would be optimal for vitrified-warmed tissues before transplantation.
Reducing Suicide-Related Stigma through Peer-to-Peer School-Based Suicide Prevention Programming
Authors: Wright-Berryman Jennifer L , Thompson Devyn , Cramer Robert J
Published: August 2022

Youth suicide rates have consistently risen over the past decade, and stigma related to mental health may create a barrier to young people seeking help. Schools are a common intercept point for mental health and suicide prevention programming. Hope Squad, a school-based, peer-to-peer, suicide prevention program, uses trained and mentored students nominated by their peers to perform intentional outreach with fellow students. When a Hope Squad member detects a mental health or suicide crisis in a peer, they alert a trusted adult. We employed a cohort, wait-list–control, cross-sectional survey design. We recruited more than 3,400 students from nine schools—five with Hope Squads and four without—to observe differences in student-body suicide-related stigma. At the end of the academic year, there was significantly lower stigma in Hope Squad schools versus those without the program. Findings suggest that a peer-to-peer, school-based, suicide prevention program may reduce stigmatizing attitudes related to suicide. Next steps include a randomized controlled trial to identify changes in help-seeking and similar protective factors.
Cutaneous manifestations in Costello syndrome: HRAS p.Gly12Ser affects RIN1-mediated integrin trafficking in immortalized epidermal keratinocytes
Authors: Nauth Theresa , Bazgir Farhad , Voß Hannah , Brandenstein Laura I , Mosaddeghzadeh Niloufar , Rickassel Verena , Deden Sophia , Gorzelanny Christian , Schlüter Hartmut , Ahmadian Mohammad R , Rosenberger Georg
Published: August 2022

Heterozygous germline missense variants in the HRAS gene underlie Costello syndrome (CS). The molecular basis for cutaneous manifestations in CS is largely unknown. We used an immortalized human cell line, HaCaT keratinocytes, stably expressing wild-type or CS-associated (p.Gly12Ser) HRAS and defined RIN1 as quantitatively most prominent, high-affinity effector of active HRAS in these cells. As an exchange factor for RAB5 GTPases, RIN1 is involved in endosomal sorting of cell-adhesion integrins. RIN1-dependent RAB5A activation was strongly increased by HRASGly12Ser, and HRAS-RIN1-ABL1/2 signaling was induced in HRASWT- and HRASGly12Ser-expressing cells. Along with that, HRASGly12Ser expression decreased total integrin levels and enriched β1 integrin in RAB5- and EEA1-positive early endosomes. The intracellular level of active β1 integrin was increased in HRASGly12Ser HaCaT keratinocytes due to impaired recycling, whereas RIN1 disruption raised β1 integrin cell surface distribution. HRASGly12Ser induced co-localization of β1 integrin with SNX17 and RAB7 in early/sorting and late endosomes, respectively. Thus, by retaining β1 integrin in intracellular endosomal compartments, HRAS-RIN1 signaling affects the subcellular availability of β1 integrin. This may interfere with integrin-dependent processes as we detected for HRASGly12Ser cells spreading on fibronectin. We conclude that dysregulation of receptor trafficking and integrin-dependent processes such as cell adhesion are relevant in the pathobiology of CS.