bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature-variable apparatus for measuring Barnett field
Authors: Umeda Maki , Chudo Hiroyuki , Imai Masaki , Sato Nana , Saitoh Eiji
Published: June 2023

We have developed experimental equipment for observing the Barnett effect, in which mechanical rotation magnetizes an object, at low temperatures. A sample in a rotor is rotated bidirectionally using a temperature-controlled high-pressure gas. The stray field generated from the sample due to the Barnett effect was detected using a fluxgate magnetic sensor with a sensitivity on the order of several picoteslas, even at low temperatures. By replacing the rotor with a solenoid coil, the magnetic susceptibility of the sample was estimated from the stray field to be of the same order of magnitude as that due to the Barnett effect. The Barnett field was estimated using the dipole model. To assess the performance of the setup at low temperatures, measurements were performed on commercial magnetite (Fe3O4) nanogranules. We confirmed the accordance of the g′ factor between the experimental results using the present setup and those of our previous study performed at room temperature.
Controllable nitrogen doping of MOCVD Ga2O3 using NH3
Authors: Alema Fikadu , Itoh Takeki , Brand William , Osinsky Andrei , Speck James S.
Published: June 2023

We report on the controllable nitrogen doping of β-Ga2O3 as a deep acceptor dopant using ammonia diluted in nitrogen (NH3/N2) as a source of active nitrogen in the metal organic chemical vapor deposition epitaxy. The effects of the NH3/N2 flow rate and substrate temperature on the incorporation efficiency, reproducibility, and controllability of N doping into Ga2O3 were studied using secondary ion mass spectrometry measurements. With the increase in the NH3/N2 molar flow rate from ∼2 × 10−8 to ∼2 × 10−6 mol/min, the N impurities incorporated into the β-Ga2O3 increased linearly from ∼1 × 1018 to ∼2 × 1020 cm−3. At low substrate temperatures (<800 °C), hydrogen was incorporated into the film accompanying nitrogen with comparable concentrations. Despite this, the current–voltage measurements showed that the N and H co-doped films were resistive with a measured resistance of >70 MΩ for a film grown with [N] ≈ [H] of ∼8 × 1018 cm−3. X-ray on-axis (020) and off-axis (111) rocking curve ω-scans and atomic force microscopy measurements show no influence of NH3/N2 dopant on the structural and surface quality of the films. However, the presence of H promoted the growth of (110) and (1¯10) facets elongated along the [001] direction. At high growth temperatures (≥950 °C), the H concentration in the films was reduced by nearly ∼10×, but with a slight increase in the concentration of N. The results show that controllable and repeatable nitrogen doping into β-Ga2O3 can be achieved using ammonia to obtain deep acceptor doping or compensation needed for device engineering in β-Ga2O3-based power electronic devices.
Improved self-consistency of the Reynolds stress tensor eigenspace perturbation for uncertainty quantification
Authors: Matha Marcel , Morsbach Christian
Published: June 2023

The limitations of turbulence closure models in the context of Reynolds-averaged Navier–Stokes (RANS) simulations play a significant part in contributing to the uncertainty of computational fluid dynamics (CFD). Perturbing the spectral representation of the Reynolds stress tensor within physical limits is common practice in several commercial and open-source CFD solvers, in order to obtain estimates for the epistemic uncertainties of RANS turbulence models. Recent research revealed that there is a need for moderating the amount of perturbed Reynolds stress tensor to be considered due to upcoming stability issues of the solver. In this paper, we point out that the consequent common implementation can lead to unintended states of the resulting perturbed Reynolds stress tensor. The combination of eigenvector perturbation and moderation factor may actually result in moderated eigenvalues, which are not linearly dependent on the originally unperturbed and fully perturbed eigenvalues anymore. Hence, the computational implementation is no longer in accordance with the conceptual idea of the Eigenspace Perturbation Framework. We verify the implementation of the conceptual description with respect to its self-consistency. Adequately representing the basic concept results in formulating a computational implementation to improve self-consistency of the Reynolds stress tensor perturbation.
Axial water jet injection in a low head Francis turbine at part load
Authors: Kumar Sandeep , Gandhi Bhupendra K.
Published: June 2023

The part load operation of a Francis turbine generally develops a rotating vortex rope (RVR) in the draft tube, generating flow instabilities and pressure pulsations. The present work reports the axial water injection method to mitigate the RVR and its associated pulsations in the draft tube. The runner cone is modified to install a nozzle of three different designs for water jet injection. Water is injected axially at the rate of 0.5% to 2% of the main flow. Spectral analysis is performed to assess the pressure amplitude and dominating frequency affected by the water injection. Spectrogram and spatial harmonic decomposition show a reduction in synchronous and asynchronous pulsation amplitudes. The pressure recovery in the draft tube cone is also improved. The spectral analysis shows that the water injection at 1% and 1.25% is the most effective. The water injection above 1.25% to 2% causes pulsations near the draft tube bend as the water jet bounces back after striking the elbow. A sharp decrease in the Strouhal frequency is observed above 0.5% jet injection. The efficiency of the turbine is also improved by water jet injection.
Wavelet analysis of the flow field around an oscillating airfoil undergoing pure pitching motion at low Reynolds number
Authors: Ghamkhar Kamran , Ebrahimi Abbas , Shariloo Koosha
Published: June 2023

This paper investigates the flow field around a NACA (National Advisory Committee for Aeronautics) 0012 airfoil undergoing pure pitching motion using continuous wavelet transform. Wind tunnel experiments were performed with a test-stand that provides a wide range of oscillation frequencies (f = 0–10 Hz). Sinusoidal pure pitching motion was considered with respect to the quarter chord for five reduced frequencies (K = 0.05, 0.1, 0.15, 0.2, and 0.3) at a Reynolds number of Re = 6 × 104. Mean angle of attack and pitch amplitude for all the cases were considered 0° and 6°, respectively. Unsteady surface pressure measurement was conducted, and the lift coefficient was calculated based on the phase-averaged surface pressure coefficient. The unsteady velocity distributions in the airfoil wake have been measured employing a pressure rake. The results indicate that the maximum value of the lift coefficient decreases by increasing the reduced frequency due to the “apparent mass” effects. For K = 0.05, close to the quasi-steady regime, the cl-α loop approximately follows the trend of the static case. Wavelet transform was used as a tool to examine the surface and wake pressure time series. Surface pressure wavelet transform plots indicate the presence of oscillation frequency and its superharmonics. Moreover, surface pressure wavelet analysis shows that the third and higher superharmonic frequencies are sensitive to the airfoil pitch angle during the oscillation cycle. Wavelet transform on wake reveals that the effective wake width gets smaller by increasing the reduced frequency. Furthermore, the trailing edge vortices get weaker by increasing the reduced frequency.
Corrigendum to: Effects of supplementation with different concentrations of L-citrulline on the plasma amino acid concentration, reproductive hormone concentrations, antioxidant capacity, and reproductive performance of Hu ewes
Authors: Ma Yan , Zhao Guodong , Wang Caidie , An Min , Ma Chen , Liu Zhiqiang , Wang Jianguo , Yang Kailun
Published: June 2023

 Context L-citrulline (L-Cit) does not degrade in the rumen and has the ability to form peptide bonds in the body; however, it does not participate in protein synthesis.

 Aims This study aimed to evaluate the effects of L-Cit on the reproductive performance of Hu ewes.

 Methods In total, 30 ewes were randomly categorised into five groups. The control group was fed with a basic diet, whereas the Experimental Groups I, II, III, and IV were provided feed supplemented with 5, 10, 15, and 20g/day of L-Cit respectively. Blood samples of ewes were collected 4h after feeding on Day 21 of the experiment and before feeding on Day 30. The optimal supplementary feeding dose was selected on the basis of blood biochemical indexes. Overall, ninety 2-year-old ewes were classified into two groups. The control group was fed with a basic diet and the experimental group was fed with a diet supplemented with 10g/day of L-Cit. After 30days of supplementary feeding, reproductive performance of ewes was determined.

 Key results The plasma concentrations of Cit, ornithine, and arginine in ewes increased linearly with an increase in the level of L-Cit supplementation. The plasma concentrations of gonadotropin-releasing hormone, luteinising hormone, and follicle-stimulating hormone in the experimental group increased significantly compared with those in the control group. The plasma total antioxidant capacity and catalase, superoxide dismutase, and glutathione peroxidase in the experimental group were significantly higher than those in the control group, whereas the concentrations of malondialdehyde in all experimental groups were significantly lower than those in the control group. The conception, lambing, and double lambing rates of the experimental group were increased by 28.76%, 15.90%, and 40.21% respectively.

 Conclusions Supplementation with different doses of L-Cit can improve the concentrations of some plasma amino acids and reproductive hormones as well as antioxidant capacity of ewes. Supplementary feeding with 10g/day of L-Cit could increase the lambing and double lambing rates of ewes.

 Implication L-Cit can improve the reproductive performance of ewes.
Selenium speciation and characteristics of selenium-enriched crops in Guiyang seleniferous soil, southwestern China
Authors: Pan Ziping , Chen Ju , Wang Minzi , Feng Yanfei , Meng Wei
Published: June 2023

Environmental context Elemental selenium plays an important role in maintaining human health and the growth of plants and animals. We studied the availability of selenium in soils and agricultural crops in Guiyang City, China, and found that the soil is selenium-rich and the crops are selenium-enriched. These results can help to understand and improve the development of mountain agriculture and rural revitalisation. Rationale Selenium (Se) is a critical element for both maintaining human health and the growth of plants and animals. The content of Se in crops is primarily determined by its speciation in soil. Therefore, the investigation of soil Se and its speciation has become a key focus of current research. Methodology In this study, taking a typical seleniferous area in Guiyang City as the study area, we investigated selenium speciation in Se-rich soil and its distribution characteristics in both soil and crops using atomic fluorescence spectroscopy (AFS) and a five-step extraction processing methods. Moreover, we further explored the key factors that affect the distribution of Se in soil. Results The findings are summarised as follows: (1) the Se content in all investigated samples met the standards of selenium-rich soil (0.40 mg/kg). The Se content in the soil surrounding crop roots ranged from 0.96 to 4.29 mg/kg, with an average value of 2.18 mg/kg. (2) Soil Se primarily existed in organic, residual, and iron and manganese oxide-binding species. The organic, sulfide-binding, and elemental Se species were the major contributors, accounting for an average of 47.00%, while the content of water-soluble, exchangeable, and carbonate-binding Se species was significantly lower. (3) Almost all crops, regardless of their types, were found Se-enriched, accounting for approximately 89.47% of the total crops in the study area. The average Se content was 0.35, 0.12, and 0.026 mg/kg in tea, rice, and corn, respectively. Discussion Varying soil physical–chemical properties, such as the content of soil organic matter content and pH levels, etc. can impact the distribution of Se in soil differently. These findings can serve as a scientific foundation for the effective utilisation of selenium-rich land resources in Guiyang city. They can also support and facilitate the development of modern specialty and high-efficiency mountain agriculture, ultimately contributing to rural revitalisation and the national implementation of the Big Ecology Strategy.
Enhanced amygdala–cingulate connectivity associates with better mood in both healthy and depressive individuals after sleep deprivation
Authors: Chai Ya , Gehrman Philip , Yu Meichen , Mao Tianxin , Deng Yao , Rao Joy , Shi Hui , Quan Peng , Xu Jing , Zhang Xiaocui , Lei Hui , Fang Zhuo , Xu Sihua , Boland Elaine , Goldschmied Jennifer R. , Barilla Holly , Goel Namni , Basner Mathias , Thase Michael E. , Sheline Yvette I. , Dinges David F. , Detre John A. , Zhang Xiaochu , Rao Hengyi
Published: June 2023

Sleep loss robustly disrupts mood and emotion regulation in healthy individuals but can have a transient antidepressant effect in a subset of patients with depression. The neural mechanisms underlying this paradoxical effect remain unclear. Previous studies suggest that the amygdala and dorsal nexus (DN) play key roles in depressive mood regulation. Here, we used functional MRI to examine associations between amygdala- and DN-related resting-state connectivity alterations and mood changes after one night of total sleep deprivation (TSD) in both healthy adults and patients with major depressive disorder using strictly controlled in-laboratory studies. Behavioral data showed that TSD increased negative mood in healthy participants but reduced depressive symptoms in 43% of patients. Imaging data showed that TSD enhanced both amygdala- and DN-related connectivity in healthy participants. Moreover, enhanced amygdala connectivity to the anterior cingulate cortex (ACC) after TSD associated with better mood in healthy participants and antidepressant effects in depressed patients. These findings support the key role of the amygdala–cingulate circuit in mood regulation in both healthy and depressed populations and suggest that rapid antidepressant treatment may target the enhancement of amygdala–ACC connectivity.
Large-scale climate patterns offer preseasonal hints on the co-occurrence of heat wave and O
3
pollution in China
Authors: Gao Meng , Wang Fan , Ding Yihui , Wu Zhiwei , Xu Yangyang , Lu Xiao , Wang Zifa , Carmichael Gregory R. , McElroy Michael B.
Published: June 2023

Heat waves and air pollution extremes exert compounding effects on human health and food security and may worsen under future climate change. On the basis of reconstructed daily O
3
levels in China and meteorological reanalysis, we found that the interannual variability of the frequency of summertime co-occurrence of heat wave and O
3
pollution in China is regulated mainly by a combination of springtime warming in the western Pacific Ocean, western Indian Ocean, and Ross Sea. These sea surface temperature anomalies impose influences on precipitation, radiation, etc., to modulate the co-occurrence, which were also confirmed with coupled chemistry–climate numerical experiments. We thus built a multivariable regression model to predict co-occurrence a season in advance, and correlation coefficient could reach 0.81 (
P
< 0.01) for the North China Plain. Our results provide useful information for the government to take actions in advance to mitigate damage from these synergistic costressors.
X-ray 3D imaging–based microunderstanding of granular mixtures: Stiffness enhancement by adding small fractions of soft particles
Authors: Taghizadeh K. , Ruf M. , Luding S. , Steeb H.
Published: June 2023

This research focuses on performing ultrasound propagation measurements and micro-X-ray computed tomography (µXRCT) imaging on prestressed granular packings prepared with biphasic mixtures of monodisperse glass and rubber particles at different compositions/fractions. Ultrasound experiments employing piezoelectric transducers, mounted in an oedometric cell (complementing earlier triaxial cell experiments), are used to excite and detect longitudinal ultrasound waves through randomly prepared mixtures of monodisperse stiff/soft particles. While the fraction of the soft particles is increasing linearly from zero, the effective macroscopic stiffness of the granular packings transits nonlinearly and nonmonotonically toward the soft limit, remarkably via an interesting stiffer regime for small rubber fractions between 0.1 ≲
ν
≲ 0.2. The contact network of dense packings, as accessed from µXRCT, plays a key role in understanding this phenomenon, considering the structure of the network, the chain length, the grain contacts, and the particle coordination. While the maximum stiffness is due to surprisingly shortened chains, the sudden drop in elastic stiffness of the mixture packings, at
ν
≈ 0.4, is associated with chains of particles that include both glass and rubber particles (soft chains); for
ν
≲ 0.3, the dominant chains include only glass particles (hard chains). At the drop,
ν
≈ 0.4, the coordination number of glass and rubber networks is approximately four and three, respectively, i.e., neither of the networks are jammed, and the chains need to include particles from another species to propagate information.
Compositional and thermal state of the lower mantle from joint 3D inversion with seismic tomography and mineral elasticity
Authors: Deng Xin , Xu Yinhan , Hao Shangqin , Ruan Youyi , Zhao Yajie , Wang Wenzhong , Ni Sidao , Wu Zhongqing
Published: June 2023

The compositional and thermal state of Earth’s mantle provides critical constraints on the origin, evolution, and dynamics of Earth. However, the chemical composition and thermal structure of the lower mantle are still poorly understood. Particularly, the nature and origin of the two large low-shear-velocity provinces (LLSVPs) in the lowermost mantle observed from seismological studies are still debated. In this study, we inverted for the 3D chemical composition and thermal state of the lower mantle based on seismic tomography and mineral elasticity data by employing a Markov chain Monte Carlo framework. The results show a silica-enriched lower mantle with a Mg/Si ratio less than ~1.16, lower than that of the pyrolitic upper mantle (Mg/Si = 1.3). The lateral temperature distributions can be described by a Gaussian distribution with a standard deviation (SD) of 120 to 140 K at 800 to 1,600 km and the SD increases to 250 K at 2,200 km depth. However, the lateral distribution in the lowermost mantle does not follow the Gaussian distribution. We found that the velocity heterogeneities in the upper lower mantle mainly result from thermal anomalies, while those in the lowermost mantle mainly result from compositional or phase variations. The LLSVPs have higher density at the base and lower density above the depth of ~2,700 km than the ambient mantle, respectively. The LLSVPs are found to have ~500 K higher temperature, higher Bridgmanite and iron content than the ambient mantle, supporting the hypothesis that the LLSVPs may originate from an ancient basal magma ocean formed in Earth’s early history.
Regional variability in intracerebral properties of NREM to REM sleep transitions in humans
Authors: Peter-Derex Laure , von Ellenrieder Nicolás , van Rosmalen Frank , Hall Jeffery , Dubeau François , Gotman Jean , Frauscher Birgit
Published: June 2023

Transitions between wake and sleep states show a progressive pattern underpinned by local sleep regulation. In contrast, little evidence is available on non–rapid eye movement (NREM) to rapid eye movement (REM) sleep boundaries, considered as mainly reflecting subcortical regulation. Using polysomnography (PSG) combined with stereoelectroencephalography (SEEG) in humans undergoing epilepsy presurgical evaluation, we explored the dynamics of NREM-to-REM transitions. PSG was used to visually score transitions and identify REM sleep features. SEEG-based local transitions were determined automatically with a machine learning algorithm using features validated for automatic intra-cranial sleep scoring (10.5281/zenodo.7410501). We analyzed 2988 channel-transitions from 29 patients. The average transition time from all intracerebral channels to the first visually marked REM sleep epoch was 8 s ± 1 min 58 s, with a great heterogeneity between brain areas. Transitions were observed first in the lateral occipital cortex, preceding scalp transition by 1 min 57 s ± 2 min 14 s (d = −0.83), and close to the first sawtooth wave marker. Regions with late transitions were the inferior frontal and orbital gyri (1 min 1 s ± 2 min 1 s, d = 0.43, and 1 min 1 s ± 2 min 5 s, d = 0.43, after scalp transition). Intracranial transitions were earlier than scalp transitions as the night advanced (last sleep cycle, d = −0.81). We show a reproducible gradual pattern of REM sleep initiation, suggesting the involvement of cortical mechanisms of regulation. This provides clues for understanding oneiric experiences occurring at the NREM/REM boundary.
A unified understanding of minimum lattice thermal conductivity
Authors: Xia Yi , Gaines Dale , He Jiangang , Pal Koushik , Li Zhi , Kanatzidis Mercouri G. , Ozoliņš Vidvuds , Wolverton Chris
Published: June 2023

We propose a first-principles model of minimum lattice thermal conductivity (

κ

L

min

) based on a unified theoretical treatment of thermal transport in crystals and glasses. We apply this model to thousands of inorganic compounds and find a universal behavior of

κ

L

min

in crystals in the high-temperature limit: The isotropically averaged

κ

L

min

is independent of structural complexity and bounded within a range from ∼0.1 to ∼2.6 W/(m K), in striking contrast to the conventional phonon gas model which predicts no lower bound. We unveil the underlying physics by showing that for a given parent compound,

κ

L

min

is bounded from below by a value that is approximately insensitive to disorder, but the relative importance of different heat transport channels (phonon gas versus diffuson) depends strongly on the degree of disorder. Moreover, we propose that the diffuson-dominated

κ

L

min

in complex and disordered compounds might be effectively approximated by the phonon gas model for an ordered compound by averaging out disorder and applying phonon unfolding. With these insights, we further bridge the knowledge gap between our model and the well-known Cahill–Watson–Pohl (CWP) model, rationalizing the successes and limitations of the CWP model in the absence of heat transfer mediated by diffusons. Finally, we construct graph network and random forest machine learning models to extend our predictions to all compounds within the Inorganic Crystal Structure Database (ICSD), which were validated against thermoelectric materials possessing experimentally measured ultralow
κ
L
. Our work offers a unified understanding of

κ

L

min

, which can guide the rational engineering of materials to achieve

κ

L

min

.
Novel four-port RF phase change switches based on GeTe thin film
Authors: Fu Shuaishuai , Gao Libin , Peng Yu , Qu Sheng , Wang Jiamei , Chen Hongwei , Liu Ningchuan , Zhang Jihua
Published: June 2023

An indirect-heated phase-change switch (PCS) using germanium telluride (GeTe) has been fabricated using thermal actuation driven by thin film heater on the model. Switches require a low ON-state resistance and a high OFF-state resistance with OFF/ON resistance ratio of 105. The finite element analysis simulation is applied to simulate the temperature of individual node GeTe with different microwave heating pulses. Finally, in order to reduce the phase-change time and increase the switching speed of indirectly heated switching structures, a new four-port indirectly heated phase change switching structure is proposed. In this paper, the heat dissipation of the switch is increased by etching deep grooves on the back of the switch. This structure obviously reduces the phase change time compared to conventional indirectly heated phase change switches the time between ON-state and OFF-state is reduced by more than 19% and the total process is reduced by more than 47%. The GeTe PCSs with etched grooves not only significantly increases the switching speed, but also reduces the risk of recrystallization of the phase change material.
Near-field thermophotovoltaic energy conversion analysis based on enhanced radiative absorption distribution
Authors: Li Bowen , Zhang Kun , Lu Lu , Song Jinlin , Luo Zixue , Cheng Qiang
Published: June 2023

Near-field radiation has been widely shown to greatly boost the electrical power of thermophotovoltaic (TPV) cells. However, there is a lack of theoretical analysis exploring the important influences of near-field effects on radiative absorption distributions as well as TPV energy conversion performances. This work investigates the electrical performances of near-field TPV cells made of InGaSb coupled with different practical emitters such as plain tungsten (W), indium tin oxide (ITO) film, and alternate W and alumina multilayer in detail. A comprehensive analysis is conducted to systematically compare the impacts of evanescent wave tunneling, surface plasmon resonance, and hyperbolic modes on spatial distributions of radiative absorption and the profiles of local carrier concentrations. The detailed and accurate analysis reveals the crucial role of near-field radiation emitted by various emitters in charge collection efficiency, thermal photon flux penetration depth, and photocurrent generation. Thus, the results certify that the electric power could be enhanced by utilizing ITO and multilayer emitters instead of a plain W emitter. The efficiency for an ITO emitter increases with decreasing vacuum gap owing to the suppressed bulk recombination but decreases when the vacuum gap falls below 18 nm due to increased surface recombination. While the efficiency for a multilayer emitter is comparatively lower due to the larger sub-bandgap photons and inefficient n-region. Furthermore, we verify the strategies for performance improvement via decreasing the surface recombination and optimizing the p-region thickness. The underlying mechanism is interpreted based on the spatial distribution and the collection efficiency of minority carriers.
Investigation of high-performance Schottky diodes on a Ga2O3 epilayer using Cu with high barrier height, high temperature stability and repeatability
Authors: Sheoran Hardhyan , Singh Rajendra
Published: June 2023

This work reports on high-performance Schottky barrier diodes (SBDs) fabricated on Ga2O3 epilayers using Cu as Schottky contacts (SCs). The fabricated SBDs exhibited high Schottky barrier heights (SBHs) with values greater than 1.0 eV, near-unity ideality factors, and a high rectification ratio (RR) of 1012 at 300 K. Temperature-dependent current–voltage (I–V–T) and capacitance–voltage (C–V–T) measurements were performed up to 500 K. The SBHs’

ϕ

B

I
V

, calculated from the IVT characteristics, initially increased with temperature and then decreased with near-unity ideality factors. The increase in

ϕ

B

I
V

with temperatures up to 410 K indicated the spatial inhomogeneity at the metal–semiconductor interface. The observed decrease in

ϕ

B

I
V

above 410 K indicated the enhancement of barrier homogeneity at higher temperatures (⩾410 K). The decrease in

ϕ

B

I
V

above 410 K and decrease in

ϕ

B

C
V

, calculated from the CVT characteristics, with increasing temperature were assigned to the bandgap narrowing of Ga2O3. The IVT measurements were repeated many times, and the SBDs exhibited excellent thermal stability and showed high SBHs >1.0 eV, a high RR, and near-unity ideality factors. All these findings were attributed to the formation of high-work-function copper oxide thin film at the interface between Cu and Ga2O3. X-ray diffraction and x-ray photoelectron spectroscopy revealed the formation of a thin layer of high-work-function copper oxide. These findings provide the possibility to fabricate an SC with a high and homogeneous barrier and thermal stability using cheap, abundant Cu material, enabling low-cost mass production of future power semiconductor devices based on oxide semiconductors.
Half-lives for proton emission and α decay within the deformed Gamow-like model
Authors: Xiao Qiong , Cheng Jun-Hao , Wang Bing-Lin , Xu Yang-Yang , Zou You-Tian , Yu Tong-Pu
Published: June 2023

In this work, α decay and proton emission half-lives are studied by the deformed Gamow-like model, which introduces the effects of nucleus deformation. The calculations show that it is necessary to consider the deformation in the calculation for nuclei far from the shell. Moreover, this model is used to predict the proton emission half-lives of the nuclei far from the shell more accurately. The calculations indicate that our deformed model follows the Geiger-Nuttall law. Furthermore, the deformed Gamow-like model is used to study the shell structure, and we find that the number of the next neutron shell is likely to be 152. This work may benefit future research on the search for superheavy nuclei and new proton radionuclides.
Investigation of the Pd(1−x)Zn
x
alloy phase diagram using ab initio modelling approaches
Authors: Kabalan Lara , Kowalec Igor , Rigamonti Santiago , Troppenz Maria , Draxl Claudia , Catlow C Richard A , Logsdail Andrew J
Published: June 2023

The identification of the stable phases in alloy materials is challenging because composition affects the structural stability of different intermediate phases. Computational simulation, via multiscale modelling approaches, can significantly accelerate the exploration of phase space and help to identify stable phases. Here, we apply such new approaches to understand the complex phase diagram of binary alloys of PdZn, with the relative stability of structural polymorphs considered through application of density functional theory coupled with cluster expansion (CE). The experimental phase diagram has several competing crystal structures, and we focus on three different closed-packed phases that are commonly observed for PdZn, namely the face-centred cubic (FCC), body-centred tetragonal (BCT) and hexagonal close packed (HCP), to identify their respective stability ranges. Our multiscale approach confirms a narrow range of stability for the BCT mixed alloy, within the Zn concentration range from 43.75% to 50%, which aligns with experimental observations. We subsequently use CE to show that the phases are competitive across all concentrations, but with the FCC alloy phase favoured for Zn concentrations below 43.75%, and that the HCP structure favoured for Zn-rich concentrations. Our methodology and results provide a platform for future investigations of PdZn and other close-packed alloy systems with multiscale modelling techniques.
Electro-tunable metasurface for tri-state dynamic polarization switching at near-infrared wavelengths
Authors: Bhowmik Tanmay , Gupta Jegyasu , Sikdar Debabrata
Published: June 2023

Control of polarization states of light is crucial for any photonic system. However, conventional polarization-controlling elements are typically static and bulky. Metasurfaces open a new paradigm to realize flat optical components by engineering meta-atoms at sub-wavelength scale. Tunable metasurfaces can provide enormous degrees-of-freedom to tailor electromagnetic properties of light and thus have the potential to realize dynamic polarization control in nanoscale. In this study, we propose a novel electro-tunable metasurface to enable dynamic control of polarization states of reflected light. The proposed metasurface comprises a two-dimensional array of elliptical Ag-nanopillars deposited on indium-tin-oxide (ITO)–Al2O3–Ag stack. In unbiased condition, excitation of gap-plasmon resonance in the metasurface leads to rotation of x-polarized incident light to orthogonally polarized reflected light (i.e., y-polarized) at 1.55 μm. On the other hand, by applying bias-voltage, we can alter the amplitude and phase of the electric field components of the reflected light. With 2 V applied bias, we achieved a linearly polarized reflected light with a polarization angle of −45°. Furthermore, we can tune the epsilon-near-zero wavelength of ITO at the vicinity of 1.55 μm wavelength by increasing the bias to 5 V, which reduces y-component of the electric field to a negligible amplitude, thus, resulting in an x-polarized reflected light. Thus, with an x-polarized incident wave, we can dynamically switch among the three linear polarization states of the reflected wave, allowing a tri-state polarization switching (viz. y-polarization at 0 V, −45° linear polarization at 2 V, and x-polarization at 5 V). The Stokes parameters are also calculated to show a real-time control over light polarization. Thus, the proposed device paves the way toward the realization of dynamic polarization switching in nanophotonic applications.
Improved bond graph model for fault diagnosis under uncertain conditions
Authors: Chen Jie , Fan Jingwen , Zhong Yichen , Shen Chi , Ren Zhujun
Published: June 2023

The effectiveness of model-based diagnosis strongly depends on the model’s authenticity and is impacted by various uncertainties. Measurement uncertainty is governed by the probability method, and parameter uncertainty can be handled by the linear fractional transformation, whereas structure uncertainty and errors are rarely considered. In this paper, an improved bond graph (BG) model is proposed, which adopts subsystems to substitute modelling errors, namely parameter uncertainty and structure uncertainty. A multi-dimensional Fibonacci optimization algorithm is developed to identify the parameters of subsystems to obtain the subsystem-based diagnostic hybrid BG (SDHBG) model. Fault diagnosis is realized by comparing the residuals and thresholds derived from the SDHBG. Experiments are conducted to validate the key concepts of the proposed methods. Subsequently, the results suggest its effectiveness.
High-output soft-contact fiber-structure triboelectric nanogenerator and its sterilization application
Authors: He Jianwei , Guo Xuhua , Pan Caofeng , Cheng Gang , Zheng Mingli , Zi Yunlong , Cui Hongzhi , Li Xiaoyi
Published: June 2023

Infectious diseases are spreading rapidly with the flow of the world’s population, and the prevention of epidemic diseases is particularly important for public and personal health. Therefore, there is an urgent need to develop a simple, efficient and non-toxic method to control the spread of bacteria and viruses. The newly developed triboelectric nanogenerator (TENG) can generate a high voltage, which inhibits bacterial reproduction. However, the output performance is the main factor limiting real-world applications of TENGs. Herein, we report a soft-contact fiber-structure TENG to avoid insufficient friction states and to improve the output, especially at a high rotation speed. Rabbit hair, carbon nanotubes, polyvinylidene difluoride film and paper all contain fiber structures that are used to guarantee soft contact between the friction layers and improve the contact state and abrasion problem. Compared with a direct-contact triboelectric nanogenerator, the outputs of this soft-contact fiber-structure TENG are improved by about 350%. Meanwhile, the open-circuit voltage can be enhanced to 3440 V, which solves the matching problems when driving high-voltage devices. A TENG-driven ultraviolet sterilization system is then developed. The bactericidal rate of this sterilization system can reach 91%, which significantly reduces the risk of disease spread. This work improves a forward-looking strategy to improve the output and service life of the TENG. It also expands the applications of self-powered TENG sterilization systems.
Influence of the background in Compton camera images for proton therapy treatment monitoring
Authors: Borja-Lloret M , Barrientos L , Bernabéu J , Lacasta C , Muñoz E , Ros A , Roser J , Viegas R , Llosá G
Published: June 2023

Objective. Background events are one of the most relevant contributions to image degradation in Compton camera imaging for hadron therapy treatment monitoring. A study of the background and its contribution to image degradation is important to define future strategies to reduce the background in the system. Approach. In this simulation study, the percentage of different kinds of events and their contribution to the reconstructed image in a two-layer Compton camera have been evaluated. To this end, GATE v8.2 simulations of a proton beam impinging on a PMMA phantom have been carried out, for different proton beam energies and at different beam intensities. Main results. For a simulated Compton camera made of Lanthanum (III) Bromide monolithic crystals, coincidences caused by neutrons arriving from the phantom are the most common type of background produced by secondary radiations in the Compton camera, causing between 13% and 33% of the detected coincidences, depending on the beam energy. Results also show that random coincidences are a significant cause of image degradation at high beam intensities, and their influence in the reconstructed images is studied for values of the time coincidence windows from 500 ps to 100 ns. Significance. Results indicate the timing capabilities required to retrieve the fall-off position with good precision. Still, the noise observed in the image when no randoms are considered make us consider further background rejection methods.
Shape memory behaviour of polyvinyl alcohol aerogels cross-linked with Fe3+ & Cu2+ metallic ions
Authors: Mohsenian Zahra , Kokabi Mehrdad , Alamdarnejad Ghazaleh
Published: June 2023

The utter purpose of this study was to embed metal ions in polymer chains to improve the shape memory behaviour of polyvinyl alcohol (PVA) aerogels in which metal ions were used as cross-linking agents for PVA. PVA–Cu and PVA–Fe hydrogels were first prepared by adding different amounts of Cu (NO3)2.3H2O and Fe (NO3)3.9H2O salts, respectively, then aerogel samples were prepared by the freeze-drying of hydrogels. Fourier transform infrared test was employed to evaluate the chemical structure. Gravimetric and mercury porosimetry methods were performed to characterize the porosity of aerogels. Field emission scanning electron microscopy examined the microstructure of the network and the porosity of the aerogels. The shape memory behaviour of the nanocomposite aerogels was evaluated by dynamic-mechanical analysis. The test results showed that by adding 25 wt% copper salt and 40 wt% iron salt to the PVA, the maximum gel fractions were achieved. Compared to pure PVA, the recovery ratios of nanocomposite aerogels increased by about 80% and 140% and their moduli increased by more than 370% and 300%, respectively.
Design, simulation, and experimental investigation on a novel robot fish driven by piezoelectric bimorphs
Authors: Xu Jiajia , Jin Jiamei , Wang Liang , Liu Rui , Zhang Jianhui , Wu Yifeng
Published: June 2023

The efficient swimming performance of fish is a miracle of nature, and the bionic robot fish powered by smart materials can replicate the movement pattern of fish to a greater extent. To achieve a simple, flexible, and controllable underwater robot, a novel robot fish driven by piezoelectric bimorphs is proposed in this study, which has similar swimming patterns to the body and/or caudal fin propulsion swimming mode and can achieve straight travel and steering underwater. The validity and feasibility of the principles were verified by wet mode simulation. A prototype is manufactured and tested for underwater vibration characteristics to confirm the motion pattern of the caudal fin of the robot fish. It weighs 13.3 g, a length of 150 mm. The maximum uniform speed of the robot fish prototype is 53 mm s−1, the thrust is 2.213 mN, and its maximum efficiency is 0.864%.
To study the structural, electronic and optical properties of predicted stable halide perovskites ABX3
Authors: Murad Kashif , Noman Muhammad , Khan Shamim , Neffati R , Ashraf Muhammad Waqar , Murtaza G
Published: June 2023

Perovskites have gained great interest in recent times. High efficiency solar materials have been developed from this family. Here in this work, structure, optical and electronic properties of recently artificial intelligence predicted stables perovskites ABX3 are studied through DFT approach. The structural analysis is done through the generalized gradient approximation. For the band structure calculations generalized gradient as well as the modified Becke-Johnson potential are used to investigate electrical and optical properties. The density of states and electronic band structure calculations reveal that the predicted stable halides Perovskites ABX3 have ultra-high to low band gaps. In the absence of experimental results, the calculated results can be valuable for further calculations. In the optical properties of the compounds dielectric function, optical reflectivity, absorption coefficient, optical conductivity, extinction coefficient, refractive index is calculated in different ranges of energy. The maximum value of static dielectric function is observed for KNiI3 and RbIrBr3 are 3.5 and 3 respectively. The highest absorption peak among the all is observed at 26 eV for SrLiF3, while refractive index of that SrLiF3 gives peak at 24 eV then refractive index decreases below the unity as energy increases up to 27.5 eV. The suitable energy bandgaps of the new compounds in the ultraviolet to infrared region certainly appeal for their use in the diverse applications.
Light Curve Analysis of the AP Dor Binary System using Ground-based and TESS Observations
Authors: Poro A. , Fernández-Lajús E. , Madani M. , Sabbaghian G. , Nasrollahzadeh F. , Jahediparizi F.
Published: June 2023

The short-period eclipsing binary AP Dor’s first in-depth and multiband photometric solutions are presented. We made use of our eight nights of ground-based opportunity at a southern hemisphere observatory, and twelve sectors of TESS observations. We extracted eight and 1322 minima from our observations and TESS, respectively. We suggest a new linear ephemeris based on the trend of orbital period variations using the Markov chain Monte Carlo (MCMC) approach. The PHysics Of Eclipsing BinariEs (PHOEBE) Python code and the MCMC approach were utilized for the light curve analysis. This system did not require a starspot for the light curve solutions. We calculated the absolute parameters of the system by applying the Gaia DR3 parallax method. The orbital angular momentum (J
0) of AP Dor indicates that this system is located in a region corresponding to contact binaries. According to our results, this system is an overcontact binary system with a mass ratio of 0.584, a fillout factor of 48%, and an inclination of 53°. The positions of component stars in the AP Dor system on the Hertzsprung–Russell diagram are found.
Zein nanoparticles stabilized by hydrophilic small molecule stabilizer matrine deliver curcumin effectively
Authors: Liu Hong , Wei Yongquan , Li Fu , Wang Xiang , Chen Yuxin , Huang Zenghui , Liang Pengyun , Wang Lisheng
Published: June 2023

Matrine (MAR), a quinolone alkaloid, was employed to augment the stability of zein nanoparticles. The incorporation of MAR into the hydrophobic shell of zein nanoparticles was primarily achieved through hydrogen bonding. Curcumin (CUR), a hydrophobic active substance, was encapsulated in the hydrophobic core of zein/matrine nanoparticles (ZMNPs). The preparation of ZMNPs and curcumin-loaded zein/matrine nanoparticles (CZMNPs) was accomplished using an antisolvent precipitation method. The encapsulation efficiency of curcumin in ZMNPs (zein/MAR = 8:1, 20 mg zein and 2.5 mg matrine) was significantly greater (52.64%) than that of nanoparticles produced from a single zein (2.50%). CZMNPs demonstrated a notable encapsulation efficiency and loading capacity (88.30% and 7.84%, respectively) upon the addition of 2 mg of curcumin, and were capable of sustained and gradual release of curcumin in simulated intestinal fluid. Furthermore, the stability of ZMNPs was observed to be favorable across a range of environmental conditions, including pH levels of 2–4 and 6–9, salt concentrations of ≤150 mM, temperatures of ≤90 °C, and storage at room temperature for a duration of 30 days. Additionally, the inherent anti-cancer properties of MAR make CZMNPs a more efficacious inhibitor of tumor cell proliferation in vitro. Moreover, the uptake of CZMNPs by A549 cells was significantly enhanced, potentially through the process of endocytosis. Therefore, the incorporation of matrine in zein-based nanoparticles confers anticancer properties to the resulting ZMNPs. These nanoparticles can serve as encapsulating agents for bioactive compounds in pharmaceutical formulations and as a novel delivery strategy for long-term cancer care. Specifically, matrine is anticipated to function as a potential stabilizer for other nanosystems.
Estimating the Effect of a Treatment When There Is Nonadherence in a Trial
Authors: Richardson David B , Dukes Oliver , Tchetgen Tchetgen Eric J
Published: June 2023

Randomized trials offer a powerful strategy for estimating the effect of a treatment on an outcome. However, interpretation of trial results can be complicated when study subjects do not take the treatment to which they were assigned; this is referred to as nonadherence. Prior authors have described instrumental variable approaches to analyze trial data with nonadherence; under their approaches, the initial assignment to treatment is used as an instrument. However, their approaches require the assumption that initial assignment to treatment has no direct effect on the outcome except via the actual treatment received (i.e., the exclusion restriction), which may be implausible. We propose an approach to identification of a causal effect of treatment in a trial with 1-sided nonadherence without assuming exclusion restriction. The proposed approach leverages the study subjects initially assigned to control status as an unexposed reference population; we then employ a bespoke instrumental variable analysis, where the key assumption is “partial exchangeability” of the association between a covariate and an outcome in the treatment and control arms. We provide a formal description of the conditions for identification of causal effects, illustrate the method using simulations, and provide an empirical application.