bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on the Development and Countermeasures of Smart Elderly Care Demand in Chongqing
Authors: Zhao Liling , Gong Zhaomiao , He Yan , Li Ning
Published: March 2024

In the milieu of modern food consumption, public health is beleaguered by the prevalence of processed foods and a dearth of clear nutritional information, factors that are intimately linked to the surge of global health issues. Our exploration into the interplay between food labeling, dietary education, regulatory policies, and community interventions reveals a complex landscape where each element is critical to steering public health toward a more nutritious future. Through a synthesis of multi-disciplinary research and pragmatic case studies, we dissect the efficacy of current nutritional transparency practices and propose a suite of actionable strategies aimed at catalyzing improvement. We argue for the necessity of a robust, unified approach where policy reform, comprehensive education, and grassroots empowerment converge to enact substantive change. This article posits that such a collaborative and systemic endeavor is not merely beneficial but imperative for engendering informed dietary choices, mitigating the tide of nutrition-related diseases, and ultimately sculpting a framework for sustained public health advancement. Our findings illuminate the potential for significant public health outcomes through concerted action and suggest that the path to a healthier society is paved by the collective efforts of policymakers, educators, and community advocates working in tandem to combat the complexities of the contemporary food environment.
The main elements of the solution to China’s demotic violence
Authors: Yin Xuan
Published: March 2024

Domestic violence represents a complex and pervasive issue within China, deeply entrenched in historical norms and sociocultural attitudes. Even with legal reforms aimed at criminalizing domestic violence and establishing legal protections for victims, challenges persist due to the societal perception of domestic violence as a family matter. This paper critically examines the main elements necessary for effectively combating domestic violence in China—policy instruments, policy implementation, and lobbying. By dissecting the shortcomings of current measures, the paper argues for the adoption of multidimensional policy tools beyond policing and legal action, such as public awareness campaigns and persuasive strategies designed to shift societal attitudes. The significance of rigorous policy implementation is emphasized, highlighting the need for iterative enforcement and organizational learning to ensure the efficacy of domestic violence policies. Furthermore, the complex role of lobbying within China's political context is explored, demonstrating its impact on policy proposals and reforms. Overall, the paper posits the need for a comprehensive approach, involving a concerted effort from policymakers, law enforcement, and civil society to address the multifaceted challenges of domestic violence in China.
Affirmative Action and Equality of Opportunity in College Admissions
Authors: Hamilton Ross , Deng Yinzhi
Published: March 2024

This essay critically examines the efficacy of race-based affirmative action in U.S. college admissions, arguing that it fails to adequately address the root causes of racial inequality and often does not benefit the most marginalized individuals within minority groups. By exploring affirmative action through the lens of political philosophy, particularly John Rawls' conception of social justice, the essay contends that a focus on socioeconomic status rather than race would more effectively promote equality of opportunity and align with Rawlsian principles. The analysis draws on various studies and theoretical perspectives to highlight the limitations of race-based affirmative action, including its tendency to benefit economically advantaged members of minority groups and its inadequacy in addressing the diverse and complex backgrounds of individuals within these groups. The essay proposes socioeconomic affirmative action as a more equitable alternative, supported by empirical evidence suggesting that such an approach could increase both socioeconomic and racial diversity in higher education institutions. The conclusion underscores the need for systemic reforms beyond admissions policies to truly achieve a just and equitable society.
Prediction of Postoperative Range of Motion after Mobile-Bearing Medial Unicompartmental Knee Arthroplasty from the Preoperative Range of Motion and Other Preoperative Factors
Authors: Anjiki Kensuke , Hiranaka Takafumi , Tanaka Toshikazu , Fujishiro Takaaki , Okamoto Koji , Hayashi Shinya , Kuroda Ryosuke , Matsumoto Tomoyuki
Published: March 2024

Postoperative flexion after unicompartmental knee arthroplasty might be predicted from the preoperative range of motion and other preoperative factors, but this has not been sufficiently investigated. Between 2013 and 2017, 198 patients (198 knees) underwent unilateral knee arthroplasty with medial mobile-bearing unicompartmental knee arthroplasty. Range of motion was measured preoperatively and at the time of final follow-up. To investigate the accuracy of the prediction of preoperative to postoperative gain or loss of the flexion angle, we performed receiver operating characteristic analysis. Logistic regression analysis was used to evaluate other predictive factors. Change in flexion angle was significantly strongly and negatively correlated with the preoperative flexion angle (R = − 0.688; 95% confidence interval: −0.755 to −0.607; p < 0.001). Preoperative flexion angle was suggested to be a significant predictor of gain or loss of the flexion angle with the area under the curve of 0.781; the cutoff value calculated using the Youden index was 140 degrees. Logistic regression analysis showed that in addition to the preoperative flexion angle of the operated side, the postoperative flexion range was significantly affected by the patient's height and by the preoperative flexion angle of the contralateral knee. If the preoperative flexion angle in Oxford mobile-bearing medial unicompartmental knee arthroplasty is <140 degrees, the postoperative flexion angle may be improved; if it exceeds 140 degrees, the postoperative flexion angle may worsen. This predictive ability is further improved by consideration of the patient's height and the range of motion on the contralateral side.
Survival and Functional Outcome in Children with Traumatic Brain Injury Requiring Ventilatory Support: A Prospective Observational Pilot Study
Authors: TN Priyanka , Bhatia Nidhi , Jain Kajal , Gupta Sunil K. , Samra Tanvir , Sarna Rashi , Aditya Ashish S.
Published: March 2024

Background In children, incidence of traumatic brain injury is high and identifying predictors of poor outcome can help clinicians make decisions in the acute phase of treatment. We thus planned to analyze the survival and functional outcome of children following traumatic brain injury. Our study included children (1–10 years of age) requiring ventilation and admitted to trauma intensive care unit of our hospital following traumatic brain injury. Our primary aim was to determine patient outcome using the modified Glasgow Outcome Scale at 3 months following hospital discharge. Our secondary objectives included patient outcome at 1 month following discharge and factors which may affect outcome.

Methods Data (epidemiological, clinical, radiological data, and hospital course) of possible factors affecting survival and outcome of pediatric traumatic brain injury patients were collected. Patient outcome was determined using the modified Rankin Scale at the time of hospital discharge and modified Glasgow Outcome Scale at 1and 3 months following discharge.

Results At the time of hospital admission, 60% children had a Glasgow Coma Scale score of 3 to 8, and were admitted with severe head injury. At the time of discharge, 30% children had good functional outcome, with 50 and 58% children being functionally independent at 1 and 3 months following discharge, respectively. Deranged serum sodium level was an independent predictor of poor neurological outcome on multivariate analysis (coefficient: −3.90 [−5.14 to –2.66, p < 0.001]).

Conclusion Fifty-eight percent children, who were admitted to intensive care unit for mechanical ventilatory support, were functionally independent at the end of 3 months following discharge from the hospital, with modified Glasgow Outcome Scale score of 5 or “Normal.” Deranged electrolytes result in secondary brain injury, thus contributing to poor long-term outcome. Effective electrolyte management is essential to improve outcome after traumatic brain injury in children.
Ultrasound Assessment of Diaphragm Function in Traumatic Brain Injury: A Prospective Observational Study
Authors: Das Kalicharan , Kumar Subodh , Bindra Ashish , Kumar Niraj , Pathak Sharmishtha
Published: March 2024

Background Prolonged mechanical ventilation is associated with weaning failure in severe TBI patients. Ultrasound is a noninvasive modality for evaluating diaphragm function. On ultrasonography (USG), diaphragm thickness is observed to decrease over time in mechanically ventilated patients. However, little literature exists on the severity of diaphragmatic dysfunction in traumatic brain injury (TBI) patients. This study aimed to observe the changes occurring in diaphragmatic function in mechanically ventilated TBI patients.

Methods TBI patients aged 18 to 65 years, requiring mechanical ventilation, were included. USG assessment of diaphragm function was done on days 0, 3, 5 and 7 of neurotrauma intensive care unit (NICU) admission in the supine position, during sedation holiday and spontaneous breathing trial. Measurements were done at end expiration (TE) and at maximal inspiration (TI) using 7- to 13-MHz linear array probe for three consecutive times and then averaged. Thickness fraction was calculated as (TI – TE/TE) × 100. Diaphragmatic excursion (DE) was measured in the M mode using 1- to 5-MHz phased array probe, as maximal height of inspiration.

Results Forty patients were evaluated. The mean diaphragmatic thickness fraction (DTF) at days 0, 3, 5, and 7 was 33.58 ± 10.08, 33.4 ± 9.76, 32.32 ± 8.36, and 31.65 ± 8.23, respectively. Change in DTF was statistically significant on day 7 (p = 0.040). The mean DE at days 0, 3, 5, and 7 was 9.61 ± 3.99, 9.02 ± 3.46, 8.87 ± 2.63, 8.56 ± 2.74, respectively. Changes in DE over days 3, 5, and 7 were statistically significant (p < 0.001). The mean DTF was lower on day 3 in patients who were admitted for less than 20 days than those who required hospital admission for more than 20 days (p = 0.044).

Conclusion Decrease in DTF and DE over the period of 7 days was observed with a significant decrease occurring on the 7th day following TBI.
Exploring the factors affecting cruise passengers’ perceptions of value for money expressed in online reviews
Authors: Jiao Yue , Lau Yui-yip , Gao Jing
Published: March 2024

The complexity of cruise tourism is high, and various factors determine the product value. Value for money has an important effect on cruisers’ choices. This paper comprehensively discusses the effect of ship attributes and onboard and onshore experience on cruise passengers’ perception of value for money. This discussion is helpful for cruise companies to identify key attributes and subsequently implement improvement strategies. Taking nearly 100,000 items of tourist review data as samples, this paper primarily discusses the effect of cruisers’ nine-dimensional experience on the perception of value for money and the differences under different market positioning gleaned from content analysis, regression analysis and multi-group comparison. Results show that embarkation, cabin, dining, entertainment, service, fitness, activities, public room and shore excursion experiences have a significant effect on tourists’ perceptions of value for money. From the perspective of brand positioning, the situation of a luxury cruise is quite different from that of a standard and premium cruise, whereas the standard and premium cruise are similar. Furthermore, unlike standard and premium cruises, the physical attributes of luxury cruises such as ship size and launch year have no significant effect on tourists’ perceptions of value for money. Research results will help cruise companies improve tourist satisfaction and value for money based on market positioning and key attributes.
A density functional tight-binding based strategy for modeling ion bombardment and its application to Ar bombardment of silicon nitride
Authors: Cheng Erik S. , Ventzek Peter L. G. , Hwang Gyeong S.
Published: March 2024

In many modern applications, it is important to understand mechanisms of non-equilibrium chemistry and physics that are driven by low energy ion bombardment of solid surfaces. However, the study of these processes has been challenging as it demands a relatively unique balance between chemical fidelity and computational cost. To this end, we have proposed and constructed a new, high-throughput simulation pipeline based on density functional tight binding simulations. Additionally, we have extended the parameter set pbc-0-3 with the addition of Ar, thereby enabling the simulation of Ar bombardment. This pipeline was then applied to study the structural and compositional evolution of silicon nitride (SiN) under Ar bombardment. We identified a possible rate limiting step of bombardment-driven sputtering of SiN and suggested underlying mechanisms of Si and N removal. Damage from the bombardment, including generation of surface defects and Ar implantation, are further discussed. These findings and the newly developed simulation framework will serve as a useful foundation for further research in processes driven by ion bombardment.
Compositionally modulated perpendicular magnetic anisotropy in tetragonal MnxAl films
Authors: Sun Hongli , Zhao Xupeng , Han Rongkun , Zhang Chen , Liu Lei , Qin Hongrui , Xie Zhicheng , Deng Huixiong , Pan Dong , Wei Dahai , Zhao Jianhua
Published: March 2024

Rare-earth-free perpendicularly magnetized L10-MnxAl alloy holds promise for low-cost permanent magnets and high-performance spintronic devices. In this Letter, we report a large-scale modulation of perpendicular magnetic anisotropy (PMA) in MnxAl films by changing the composition x. Through utilizing a lattice-matching B2-CoGa underlayer and optimizing growth conditions, the 30-nm-thick MnxAl films can maintain excellent PMA in a wide composition range (0.7 ≤ x ≤ 3). Meanwhile, the crystalline structure and magnetic properties exhibit a strong dependence on the composition with saturation magnetization changing from 443.75 to 20.52 kA/m, coercivity from 0.22 to 5.38 T, and PMA constant up to 1.34 × 106 J/m3. Combining experimental and calculation results, we confirm the existence of ferrimagnetic-like state in MnxAl under Mn-rich conditions. Further experiments validate the continued efficacy of our method in ultrathin MnxAl films, and spin–orbit torque induced magnetization switching has been realized. These results offer valuable insights into the modulation of fundamental properties and promote the potential application of MnxAl alloy.
Implementation of field-programmable Gate array-based clock synchronization in the fiber channel communication system
Authors: Xu Huiya , Wang Guangji , Guo Lianping , Zhao Yijiu , Jiang Dongyu , Lian Ke
Published: March 2024

A sub-nanosecond clock synchronization scheme based on the field programmable gate array (FPGA) is proposed for the Fiber Channel (FC) communication system in this paper. The counter value of the slave node is synchronized to that of the master node through the embedded IEEE 1588 protocol over the communication link. In order to ensure the counter clocks have the same frequency in both nodes, which is recovered from the FC communication link, the clock phase difference is measured by the digital dual mixer time difference technique and the data recovery technique in the Gigabyte Transceiver, and then it is compensated by the mixed-mode clock manager in FPGAs. The proposed clock synchronization approach is evaluated with an FC communication system that has a serial rate of 12.5 Gbps, and the reported experimental results show that the proposed clock synchronization module can achieve a time difference lower than 1 ns.
Matrix-formation dynamics dictate methyl nitrite conformer abundance
Authors: Hockey Emily K. , McLane Nathan , Vlahos Korina , McCaslin Laura M. , Dodson Leah G.
Published: March 2024

Methyl nitrite has two stable conformational isomers resulting from rotation about the primary C–O–N–O dihedral angle: cis-CH3ONO and trans-CH3ONO, with cis being more stable by ∼5 kJ/mol. The barrier to rotational interconversion (∼45 kJ/mol) is too large for isomerization to occur under ambient conditions. This paper presents evidence of a change in conformer abundance when dilute CH3ONO is deposited onto a cold substrate; the relative population of the freshly deposited cis conformer is seen to increase compared to its gas-phase abundance, measured by in situ infrared spectroscopy. We observe abundance changes depending on the identity of the bath gas (N2, Ar, and Xe) and deposition angle. The observations indicate that the surface properties of the growing matrix influence conformer abundance—contrary to the widely held assumption that conformer abundance in matrices reflects gas-phase abundance. We posit that differences in the angle-dependent host-gas deposition dynamics affect the growing surfaces, causing changes in conformer abundances. Quantum chemistry calculations of the binding energies between CH3ONO and a single bath-gas component reveal that significant energetic stabilization is not observed in 1:1 complexes of N2:CH3ONO, Ar:CH3ONO, or Xe:CH3ONO. From our results, we conclude that the growing surface plays a significant role in trapping cis-CH3ONO more effectively than trans-CH3ONO, likely because cis-CH3ONO is more compact. Taken together, the observations highlight the necessity for careful characterization of conformers in matrix-isolated systems, emphasizing a need for further study into the deposition dynamics and surface structure of chemically inert matrices.
Calibration of second harmonic generation technique to probe the field-effect passivation of Si(100) with Al2O3 dielectric layers
Authors: Obeid B. , Bastard L. , Bouchard A. , Aubriet V. , Jouannic K. , Le Cunff D. , Gourhant O. , Ionica I.
Published: March 2024

Optical second harmonic generation (SHG) can be employed to characterize the passivation quality of semiconducting material interfaces. The interface electric field (EDC) related to the existing charges at and near the interface, including the fixed oxide charges Qox, gives rise to the electric field induced second harmonic phenomenon. In this paper, we calibrate the SHG response for EDC measurement, using Al2O3/SiO2/Si(100) samples with different Qox. To perform this calibration, SHG and capacitance-voltage measurements (to access the electrical field of the samples) were made. The experimental results match well the simulated calibration curve, proving the potential of the SHG as stand-alone characterization technique for dielectric stacks on Si.
Quantifying the thickness of WTe2 using atomic-resolution STEM simulations and supervised machine learning
Authors: Dihingia Nikalabh , Vázquez-Lizardi Gabriel A. , Wu Ryan J. , Reifsnyder Hickey Danielle
Published: March 2024

For two-dimensional (2D) materials, the exact thickness of the material often dictates its physical and chemical properties. The 2D quantum material WTe2 possesses properties that vary significantly from a single layer to multiple layers, yet it has a complicated crystal structure that makes it difficult to differentiate thicknesses in atomic-resolution images. Furthermore, its air sensitivity and susceptibility to electron beam-induced damage heighten the need for direct ways to determine the thickness and atomic structure without acquiring multiple measurements or transferring samples in ambient atmosphere. Here, we demonstrate a new method to identify the thickness up to ten van der Waals layers in Td-WTe2 using atomic-resolution high-angle annular dark-field scanning transmission electron microscopy image simulation. Our approach is based on analyzing the intensity line profiles of overlapping atomic columns and building a standard neural network model from the line profile features. We observe that it is possible to clearly distinguish between even and odd thicknesses (up to seven layers), without using machine learning, by comparing the deconvoluted peak intensity ratios or the area ratios. The standard neural network model trained on the line profile features allows thicknesses to be distinguished up to ten layers and exhibits an accuracy of up to 94% in the presence of Gaussian and Poisson noise. This method efficiently quantifies thicknesses in Td-WTe2, can be extended to related 2D materials, and provides a pathway to characterize precise atomic structures, including local thickness variations and atomic defects, for few-layer 2D materials with overlapping atomic column positions.
Collisional space-charge-limited current with monoenergetic velocity: From Child–Langmuir to Mott–Gurney
Authors: Breen Lorin I. , Garner Allen L.
Published: March 2024

All theories coupling electron emission theories ultimately approach the space-charge-limited current (SCLC) in vacuum, given by the Child–Langmuir (CL) law, for sufficiently high voltage, or the Mott–Gurney (MG) law for finite electron mobility and high (but not infinite) voltage. These analyses demonstrate the presence of an SCLC regime that cannot be described by either CL or MG. Here, we derive an exact solution for SCLC for general electron mobility and nonzero velocity. We recover the traditional CL with nonzero initial velocity at high voltage. For low mobility (or infinite collision frequency), we derive corrections to the MG law that depend on the ratio of initial velocity to the product of collision frequency and gap distance or initial velocity to drift velocity for low and high voltage, respectively. Increasing collisionality decreases the correction to SCLC for nonzero velocity, indicating that these corrections are less important for low-mobility materials (e.g., solids) than high-mobility materials (e.g., air or vacuum). For a given gap distance (collision frequency), increasing the collision frequency (gap distance) increases the voltage necessary to make the gap appear more like vacuum. These results provide a generalized SCLC for both collisionality and initial velocity when assessing the transitions between electron emission mechanisms.
Effect of Prandtl number and free-stream orientation on global parameters for flow past a heated square cylinder
Authors: Ali Rashid , Arif Md. Reyaz , Haider Syed Aley , Shamim Farhan Ahmad
Published: March 2024

In this study, an in-depth examination of the aerodynamic parameters involving forced and mixed convection around a heated square cylinder is presented. The ranges of Prandtl number (Pr), Richardson number (Ri), and flow orientation (α) are kept as 0.71 ≤ Pr ≤ 1000, 0 ≤ Ri ≤ 1.6, 0° ≤ α ≤ 90°, while the Reynolds number (Re) and the cylinder orientation (ϕ) are kept fixed as Re = 100 and ϕ = 0°, respectively. The flow is considered as two-dimensional (2D), steady, laminar, incompressible, and viscous. The buoyancy effects are taken into account through the Boussinesq approximation. At lower Pr, the flow shifts from unsteady to steady with increasing Ri. This transition persists at higher Ri with increasing Prandtl values. The flow remains consistently unsteady at α = 90°. Isotherm crowding intensifies with higher Pr and/or Ri across all flow inclinations. Across the complete spectrum of flow angles, it is noted that the mean lift coefficient rises as the Richardson number increases. Additionally, the mean drag coefficient reaches its peak at Ri = 1.6 when Pr = 0.71. The findings reveal that the Strouhal number (St) rises as the Richardson number (Ri) increases, and it decreases as the Prandtl number (Pr) increases. The mean Nusselt number (Nu¯) demonstrates an upward trend as the Prandtl number increases, with Ri held constant. It is also observed that Nu¯ is more sensitive to the Prandtl number than the Richardson number and is maximum at Pr = 1000 for the selected range of flow orientations.
Dynamic performance and wake flow characteristics of flow around a plate in a circular tube
Authors: Lin Zhe , Jiang Jingyu , Wang Wei , Tao Junyu , Zhu Zuchao
Published: March 2024

The flow around a plate is a classic problem in fluid dynamics, with applications in fields such as aerospace, construction, energy, and chemical engineering. This paper studies the flow around a plate in a circular tube. The detached-eddy simulation method is used to calculate the unsteady flow near the plate, allowing the mechanical and wake flow characteristics of the plate to be analyzed at different open angles and the influence of the plate dome degree to be further investigated. The variation laws of the plate torque and pressure under the unsteady flow inside the circular tube are obtained. By comparing and analyzing the time-averaged velocity and instantaneous velocity fluctuations of the wake flow on the plate, the flow field distribution patterns under different structures and open angles are identified, and the unstable region of the wake flow is determined. The results presented in this paper provide a theoretical reference for applications involving the flow around a plate.
Characterization of experimental and simulated micrometer-scale soft x-ray-emitting laser plasmas: Toward predictive radiance calculations
Authors: Mongey K. , de Lange S. J. J. , Brady R. , Hemminga D. J. , Delaney B. , Basko M. M. , Sokell E. , O'Reilly F. , Sheil J.
Published: March 2024

Experimentally generated and simulated soft x-ray plasma images and spectra from 1064 nm-driven laser-produced plasmas from slab tin are presented. Produced are small, micrometer-scale emission volumes with principle imaged emission lying between 1.2 and 2.5 nm. Experimental images of the soft x-ray emission of these plasmas are generated using a pinhole imaging system, which enables spatial characterization of the plasmas, and a simple transmission grating spectrometer with a 100 nm pitch grating is used to facilitate the spectral characterization of these plasmas. Plasmas are simulated under similar experimental conditions to those used with the single-fluid, single-temperature radiation-hydrodynamics code RALEF-2D. Coupling the simulation output with optical modeling methods demonstrates its promise as a capability for modeling the spatial and spectral behavior of soft x-ray-emitting tin plasmas at such scales and laser energies.
A phenomenological thermodynamic energy density function for ferroelectric wurtzite Al1−xScxN single crystals
Authors: Gu Yijia , Meng Andrew C. , Ross Aiden , Chen Long-Qing
Published: March 2024

A Landau–Devonshire thermodynamic energy density function for ferroelectric wurtzite aluminum scandium nitride (Al1−xScxN) solid solution is developed. It is parametrized using available experimental and theoretical data, enabling the accurate reproduction of composition-dependent ferroelectric properties, such as spontaneous polarization, dielectric permittivity, and piezoelectric constants, for both bulk and thin films. The maximum concentration of Sc for the wurtzite structure to remain ferroelectric is found to be 61 at. %. A detailed analysis of Al1−xScxN thin films reveals that the ferroelectric phase transition and properties are insensitive to substrate strain. This study lays the foundation for quantitative modeling of novel ferroelectric wurtzite solid solutions.
On the propagation of planar gravity currents into a stratified ambient
Authors: Zahtila Tony , Lam Wai Kit , Chan Leon , Sutherland Duncan , Moinuddin Khalid , Dai Albert , Skvortsov Alex , Manasseh Richard , Ooi Andrew
Published: March 2024

Gravity currents are of high interest both for their relevance in natural scenarios and because varying horizontal buoyancy presents a canonical problem in fluid mechanics [Huppert, “Gravity currents: A personal perspective,” J. Fluid Mech. 554, 299–322 (2006)]. In this paper, attention is directed to gravity currents with a full-depth lock release propagating into a linearly stratified ambient fluid. For the case of an unstratified ambient, similarity solutions are known to capture the evolving height profile of the gravity current. We will compare this solution class with numerical data from high fidelity simulations. The presence of ambient stratification (quantified by the stratification intensity, S) introduces internal gravity waves that interact with the propagating current head, which will inhibit Kelvin–Helmholtz billows, decelerate current propagation, and smooth the shape of the current head. We perform direct numerical simulations of planar two- and three-dimensional gravity currents released into stratified ambient fluid of varying S and analyze the gravity current kinematics. Our analysis complements existing findings from performed laboratory and numerical experiments [Dai et al., “Gravity currents propagating at the base of a linearly stratified ambient,” Phys. Fluids 33, 066601 (2021)] that show a stratified ambient modifies the current front velocity. Previous literature employed has inconsistent Reynolds numbers and boundary conditions, complicating interpretations. In the present numerical campaign, a closer analysis clarifies influence of the top boundary condition choice on formation and structure of the internal gravity waves. While acknowledging there is no available choice for a high-accuracy simplified numerical representation of a free-surface, a family of profiles for internal wave formation emerges varying with buoyancy Reynolds number and top boundary condition selection. The subsequent results appraise similarity solutions for the distribution of the heavy fluid in the gravity current. Our results show that for unstratified and low stratification ambient fluid, height profiles permit a similarity solution but higher values of S are less amenable; these profiles suggest a continuing time dependency on the traveling internal wave.
Extraction of gap states in AlSiO/AlN/GaN metal-oxide-semiconductor field-effect transistors using the multi-terminal capacitance–voltage method
Authors: Narita Tetsuo , Ito Kenji , Iguchi Hiroko , Iwasaki Shiro , Tomita Kazuyoshi , Kikuta Daigo
Published: March 2024

Direct extraction of gap states from a metal-oxide-semiconductor field-effect transistor (MOSFET) in which inversion electrons and holes in a p-type body coexist is challenging. We demonstrate gap-state extraction in lateral-type GaN MOSFETs with high channel mobilities using multi-terminal capacitance–voltage (C–V) methods. The gate stack of the MOSFET was composed of AlSiO/AlN/p-type GaN formed on a p+/n+ GaN tunnel junction structure. The substrate electrode was short-circuited to a p-type body layer through the tunnel junction. The MOSFET was equipped with gate, source, drain, body, and substrate electrodes. When the gate was the high side and the other electrodes were the low side in the AC circuit, a V-shaped C–V curve was obtained because of electron inversion and hole accumulation. When the body/substrate electrodes were connected to the ground level (i.e., split C–V method), the inversion electrons between the gate and source/drain electrodes could be evaluated. We proposed a “reverse” split C–V method in which the source/drain electrodes are grounded and the body/substrate electrodes are connected to the low side. This method enabled extraction of gap states near the valence-band maximum of GaN, with exclusion of the overlap capacitance and the capacitance due to inversion electrons. The proposed method demonstrated overall gap states in the GaN MOSFET with a wide bandgap. The results suggest that hole traps with discrete energy levels caused negative bias instability (NBI) in the GaN MOSFET. Furthermore, NBI and discrete gap states were consistently suppressed by Mg doping at >1018 cm−3 into a p-type body.
Signature of phonon anharmonicity in highly in-plane anisotropic ternary HfGeTe4 single crystals
Authors: Muhammad Zahir , Rehman Zia ur , Muhammad Nisar , Zawadzka Natalia , Hussain Ghulam , Islam Rajibul , Babiński Adam , Molas Maciej R. , Zhang Yue , Zhao Weisheng
Published: March 2024

Ternary layered single crystals of HfGeTe4 have been synthesized and systematically investigated to study their electronic and vibrational properties using angle-resolved photoemission spectroscopy and Raman scattering (RS) spectroscopy. The experimental results were supported through density functional theory by calculating the electronic band structures, phonons dispersion, lattice thermal conductivity (κL), and phonon lifetimes. The measured Fermi surfaces represent integrated intensities at different binding energies along the opposite symmetry directions, revealing the anisotropic Fermi surfaces. Their band structure shows different band curvatures in the high symmetry direction with anisotropic band dispersions. Moreover, the change in magnetoresistance under different orientations reveals anisotropic electrical conductivity, which further supports our results of 2D anisotropic crystals. HfGeTe4 shows a strong in-plane anisotropic response under polarized RS with phonon intensities changing with the rotation angle, manifesting twofold and fourfold symmetry orientations. Furthermore, the Raman scattering spectra show phonon softening observed with increasing temperature, which could be attributed to the phonon anharmonicity estimated from both the frequency shift and linewidth. The results were further supported by lattice-dynamics calculations. We have found very low lattice thermal conductivity (∼0.31 Wm−1 K−1 at 300 K), which decays as the temperature is increased due to enhanced phonon–phonon scattering, as confirmed by the decreased phonon lifetimes at higher temperatures. The unique structure of this material coupled with the anisotropy and strong phonon anharmonicity depicts significant potential in 2D nanoelectronic applications.
A new rapid deflagration-to-detonation transition in a short smooth tube
Authors: Zhao Wandong , Fan Caizhi , Deiterding Ralf , Li Xiaokang , Liang Jianhan , Yang Xiong
Published: March 2024

Obtaining a rapid deflagration-to-detonation transition (DDT) within a short smooth tube is a challenging task. Here, an unconventional means of flame acceleration propagating upstream in subsonic and supersonic mixtures within a smooth tube was introduced to acquire a speedy DDT. The Navier–Stokes equations with an adaptive mesh refinement technique and a detailed hydrogen–air chemistry reaction mechanism of 11 species and 27 steps were utilized to resolve the entire DDT characteristics. The effect of the initial Mach number on flame acceleration and DDT mechanism was revealed comprehensively. The results demonstrated that a prompt oblique shock wave (SW) occurs when the flame propagates upstream along the boundary walls due to the boundary layer influence. An intense coupling between the SW and the leading flame front is enhanced by increasing the initial Mach number of the mixture. The speedy generation of the oblique SW is formed at the incipient stage, mainly produced by the boundary layer influence and the coalescences of the compression waves. Consequently, the run-up time to detonation is shortened accordingly through a fierce reflected SW due to the intense leading SW after it reflects from the confined wall. Furthermore, three kinds of DDT evolution are revealed from the obtained results: (1) localized ignition in the upper boundary wall after the reflected and transverse shock waves propagate in the upper wall regions; (2) autoignition is formed in the confined wall corner after the reflected SW; and (3) direct detonation transition occurs at the end wall behind a strongly reflected SW in the supersonic case.
Highly uniform fabrication of femtosecond-laser-modified silicon materials enabled by temporal pulse shaping
Authors: Zhou Xu , Chen Lu , Wu Qiang , Zheng Ziyang , Song Guanting , Huang Song , Xu Jingjun
Published: March 2024

Femtosecond-laser modified silicon materials have excellent optoelectronic properties and device application prospects, thus capturing pervasive interest from academia and industry. Nevertheless, efficiently achieving large-area uniform modification on silicon surfaces with Gaussian laser beams, especially fabricating evenly and extensively distributed microcone structures, remains a formidable obstacle. Our theoretical and experimental investigations demonstrate that the pulse-shaping technique effectively regulates the light–matter interaction, leading to improved surface uniformity through nonlinear and linear modulation. A large-area uniformly distributed microcones are prepared on the silicon surface through pure temporal modulation of the pulse. In addition, the method is easy to implement and has good compatibility. These findings carry significant implications for advancing the femtosecond-laser processing technology and promoting the industrial utilization of modified silicon materials, including photoelectric detection and solar cell fields.
Dynamics of a strongly coupled quantum heat engine—Computing bath observables from the hierarchy of pure states
Authors: Boettcher Valentin , Hartmann Richard , Beyer Konstantin , Strunz Walter T.
Published: March 2024

We present a fully quantum dynamical treatment of a quantum heat engine and its baths based on the Hierarchy of Pure States (HOPS), an exact and general method for open quantum system dynamics. We show how the change of the bath energy and the interaction energy can be determined within HOPS for arbitrary coupling strength and smooth time dependence of the modulation protocol. The dynamics of all energetic contributions during the operation can be carefully examined both in its initial transient phase and, also later, in its periodic steady state. A quantum Otto engine with a qubit as an inherently nonlinear work medium is studied in a regime where the energy associated with the interaction Hamiltonian plays an important role for the global energy balance and, thus, must not be neglected when calculating its power and efficiency. We confirm that the work required to drive the coupling with the baths sensitively depends on the speed of the modulation protocol. Remarkably, departing from the conventional scheme of well-separated phases by allowing for temporal overlap, we discover that one can even gain energy from the modulation of bath interactions. We visualize these various work contributions using the analog of state change diagrams of thermodynamic cycles. We offer a concise, full presentation of HOPS with its extension to bath observables, as it serves as a universal tool for the numerically exact description of general quantum dynamical (thermodynamic) scenarios far from the weak-coupling limit.
Schottky contacts on sulfurized silicon carbide (4H-SiC) surface
Authors: Roccaforte Fabrizio , Vivona Marilena , Panasci Salvatore Ethan , Greco Giuseppe , Fiorenza Patrick , Sulyok Attila , Koos Antal , Pecz Bela , Giannazzo Filippo
Published: March 2024

In this Letter, the effect of a sulfurization treatment carried out at 800 °C on silicon carbide (4H-SiC) surface was studied by detailed chemical, morphological, and electrical analyses. In particular, x-ray photoelectron spectroscopy confirmed sulfur (S) incorporation in the 4H-SiC surface at 800 °C, while atomic force microscopy showed that 4H-SiC surface topography is not affected by this process. Notably, an increase in the 4H-SiC electron affinity was revealed by Kelvin Probe Force Microscopy in the sulfurized sample with respect to the untreated surface. The electrical characterization of Ni/4H-SiC Schottky contacts fabricated on sulfurized 4H-SiC surfaces revealed a significant reduction (∼0.3 eV) and a narrower distribution of the average Schottky barrier height with respect to the reference untreated sample. This effect was explained in terms of a Fermi level pinning effect induced by surface S incorporation.
Does the van der Waals force play a part in evaporation?
Authors: Benilov E. S.
Published: March 2024

It is argued that the van der Waals force exerted by the liquid and vapor/air on the molecules escaping from one phase into the other strongly affects the characteristics of evaporation. This is shown using two distinct descriptions of the van der Waals force: the Vlasov and diffuse-interface models, each of which is applied to two distinct settings: a liquid evaporating into its vapor and a liquid evaporating into air (in all cases, the vapor-to-liquid density ratio is small). For the former setting, the results are consistent with the Hertz–Knudsen law (HKL), but the evaporation/condensation probability is very small (in the classical HKL, it is order one). For the latter setting, the dependence of the evaporation rate on the difference between the saturated vapor pressure and its actual value is shown to be nonlinear (whereas the classical HKL predicts a linear dependence). The difference between the two settings indicates that the van der Waals force exerted by the air strongly affects evaporation (contrary to the general assumption that the ambient gas is unimportant). Finally, the diffuse-interface model is shown to be inapplicable in a narrow region at the outskirts of the interface—as a result, it noticeably underestimates the evaporative flux by comparison with the (more accurate) Vlasov model.
Monocrystalline silicon metasurfaces enabled aperture-robust reconstructive spectrometer for visible light
Authors: Xu Weizhu , Fan Qingbin , Lin Peicheng , Wang Jiarong , Hu Hao , Yue Tao , Hu Xuemei , Xu Ting
Published: March 2024

In contrast to conventional grating-based spectrometers, reconstructive spectrometers based on spectrally engineered filtering offer a notable advantage in terms of miniaturization due to reduced requirements for dispersive optics and free propagation space. Nevertheless, existing reconstructive spectrometers encounter challenges in optimizing operational bandwidth, reconstruction fidelity, and angular stability concurrently. Here, we introduce a compact spectrometer employing dielectric metasurfaces, designed to operate across a broad bandwidth spanning 400–800 nm with high aperture stability. Experimental validation demonstrates the capability of accurately reconstructing incident hyperspectral signals, focused by a lens with varying F-numbers between F/1.8 and F/8, with elevated fidelity. The compatible optical prototype highlights the potential for constructing broadband, high accuracy, integrated hyperspectral cameras.
The physical origin of inhomogeneous field within HfO2-based ferroelectric capacitor
Authors: Ke Xiaoyu , Dai Saifei , Xu Hao , Chai Junshuai , Wang Xiaolei , Wang Wenwu
Published: March 2024

In this work, the origins of the inhomogeneous field within the HfO2-based ferroelectric (FE) capacitor are investigated. We propose a model to simulate the relationship between the reversed polarization and the applied pulses with different amplitudes and durations. The electric field distribution is considered to be influenced by the ferroelectric layer thickness (tFE) and the built-in field (Eb). Then, the distribution parameters of both two physical factors and the Merz law, which define the switching dynamics, could be obtained by fitting the experimental results. Comparing with the results of high-resolution transmission electron microscope and first-order reversal curve measurements, it can be reasonably concluded that the physical origin of the inhomogeneous field in HfO2-based ferroelectrics is the random distribution of tFE and Eb. This work improves the understanding of the switching dynamics by providing the origins of the inhomogeneous field in an FE film.
Multiple phase transitions in shock compressed high-entropy alloy Cr9Mn9Fe64Co9Ni9: Experiments and molecular dynamics simulations
Authors: Zhang Yi , Zhang Ningbo , Tang Yu , Cai Yang , Lu Lei , Luo Shengnian
Published: March 2024

Dynamic response of a non-equiatomic high-entropy alloy, Cr9Mn9Fe64Co9Ni9, to shock compression is investigated via plate impact along with in situ free surface velocity measurements. Postmortem samples are characterized with transmission electron microscopy and electron backscatter diffraction. After shock compression, microstructure characterizations reveal shock-induced stacking faults, the Lomer–Cottrell dislocation locks, nanotwins, and the face-centered cubic (FCC) to hexagonal close-packed (HCP) and FCC to body-centered cubic (BCC) transitions. The HCP and BCC phases follow Shoji–Nishiyama and Kurdyumov–Sachs orientation relations with the FCC matrix, respectively. Large-scale molecular dynamics simulations are conducted to illustrate the phase transition mechanisms. The BCC phase can form via the FCC–HCP–BCC path.
A marine record of Patagonian ice sheet changes over the past 140,000 years
Authors: Hagemann Julia R. , Lamy Frank , Arz Helge W. , Lembke-Jene Lester , Auderset Alexandra , Harada Naomi , Ho Sze Ling , Iwasaki Shinya , Kaiser Jérôme , Lange Carina B. , Murayama Masafumi , Nagashima Kana , Nowaczyk Norbert , Martínez-García Alfredo , Tiedemann Ralf
Published: March 2024

Terrestrial glacial records from the Patagonian Andes and New Zealand Alps document quasi-synchronous Southern Hemisphere–wide glacier advances during the late Quaternary. However, these records are inherently incomplete. Here, we provide a continuous marine record of western–central Patagonian ice sheet (PIS) extent over a complete glacial–interglacial cycle back into the penultimate glacial (~140 ka). Sediment core MR16-09 PC03, located at 46°S and ~150 km offshore Chile, received high terrestrial sediment and meltwater input when the central PIS extended westward. We use biomarkers, foraminiferal oxygen isotopes, and major elemental data to reconstruct terrestrial sediment and freshwater input related to PIS variations. Our sediment record documents three intervals of general PIS marginal fluctuations, during Marine Isotope Stage (MIS) 6 (140 to 135 ka), MIS 4 (~70 to 60 ka), and late MIS 3 to MIS 2 (~40 to 18 ka). These higher terrigenous input intervals occurred during sea-level low stands, when the western PIS covered most of the Chilean fjords, which today retain glaciofluvial sediments. During these intervals, high-amplitude phases of enhanced sediment supply occur at millennial timescales, reflecting increased ice discharge most likely due to a growing PIS. We assign the late MIS 3 to MIS 2 phases and, by inference, older advances to Antarctic cold stages. We conclude that the increased sediment/meltwater release during Southern Hemisphere millennial-scale cold phases was likely related to higher precipitation caused by enhanced westerly winds at the northwestern margin of the PIS. Our records complement terrestrial archives and provide evidence for PIS climate sensitivity.