bluuebunny/crossref_metadata_2025 huggingface dataset:
Chasing Gold: Heat Acclimation in Elite Handcyclists with Spinal Cord
Injury
Authors: Lackner Mike , Grossmann Fabian , Perret Claudio , Flueck Joelle L , Hertig-Godeschalk Anneke
Published: June 2024

Thermoregulation is impaired in individuals with a spinal cord lesion (SCI),
affecting sweat capacity, heat loss, and core temperature. This can be
particularly problematic for athletes with SCI who exercise in hot and humid
conditions, like those during the Tokyo 2020 Paralympic Games. Heat acclimation
can support optimal preparation for exercise in such challenging environments,
but evidence is limited in endurance athletes with SCI. We evaluated whether
seven consecutive days of exercise in the heat would result in heat acclimation.
Five elite para-cycling athletes with SCI participated (two females, three
males, median (Q1-Q3) 35 (31–51) years, four with paraplegia and one with
tetraplegia). All tests and training sessions were performed in a heat chamber
(30°C and 75% relative humidity). A time-to-exhaustion test was performed on day
1 (pretest) and day 7 (posttest). On days 2–6, athletes trained daily for one
hour at 50–60% of individual peak power (PPeak). Comparing pretest
and posttest, all athletes increased their body mass loss (p=0.04), sweat rate
(p=0.04), and time to exhaustion (p=0.04). Effects varied between athletes for
core temperature and heart rate. All athletes appeared to benefit from our heat
acclimation protocol, helping to optimize their preparation for the Tokyo 2020
Paralympic Games.
Multicenter clinical trial on functional evaluation of transoral laser microsurgery for supraglottic laryngeal carcinomas
Authors: Ambrosch Petra , Fazel Asita , Dietz Andreas , Fietkau Rainer , Tostmann Ralf , Borzikowsky Christoph
Published: June 2024

Background Transoral laser microsurgery (TLM) is an accepted and effective treatment strategy for supraglottic carcinomas. Data on oncologic and to a lesser extent functional outcomes have been published by mainly European specialized single institutions. TLM for supraglottic carcinomas has never been tested in a multicenter trial on its applicability as surgical standard at every hospital.

Objectives To test the efficacy of TLM supraglottic laryngectomy (TLM-SGL) in terms of swallowing function, oncologic outcome parameters, morbidity, complications of treatment, and quality of life in a multicenter setting.

Methods The study is designed as a multicenter (approximately 25 centers), non-randomized, single-arm study with a targeted number of 200 previously untreated patients with squamous cell carcinomas (SCC) of the supraglottic larynx T2/T3 N0–3 M0; UICC stage II–IVa. The surgical treatment consists of TLM-SGL and elective or therapeutic uni- or bilateral selective neck dissection (SND). After pathologic risk stratification adjuvant radio- (RT) or radiochemotherapy (RCT) is indicated. Patients are followed-up for 2 years post surgically. Swallowing function is assessed by fibreoptic endoscopic evaluation of swallowing (FEES). The primary endpoint is aspiration-free swallowing at 12 months as established using FEES and defined as grade < 6 of penetration-aspiration scale (PAS). Secondary endpoints include local control, larynx preservation, overall and disease-free survival, complications and side effects of treatment, prevalence of tracheostomy and percutaneous endoscopic gastrostomy (PEG)-tube-feeding, and dysphagia-specific quality of life (QoL) assessed by the MD Anderson Dysphagia Inventory (MDADI) as well as voice-related QoL assessed by the Voice Handicap Index (VHI).
Patients With Chronic Pain: The Aspect Of Negative Body
Image
Authors: Kieselbach Kristin , Fauler Ingrid , Abberger Birgit
Published: June 2024

Objective Negative body image is an increasingly important factor in
chronic pain disorders; particularly because the two conditions mutually
influence each other. Our study examines body-image-related attitudes and
comorbid psychic symptoms in patients with chronic pain disorders.

Methods and Measures 188 patients with chronic pain answered the Dresden
body image questionnaire (DKB-35), the Hospital Anxiety and Depression Scale
(HADS) and the Beck’s Depression Inventory (BDI).

Results The mean values of the DKB-35 subscales range between 2.24 und
3.29. The subscale “vitality” has the lowest mean value. BDI and HADS correlated
significantly with the DKB-35 subscales. The subscale “body-acceptance”
intercorrelated high with the two subscales “vitality” and
“self-aggrandizement”.

Conclusion Our findings verify that chronic pain is strongly associated
with negative body image. The issues of vitality and psychological symptoms seem
particularly central in this complex interaction. The biopsycho-social model and
the avoidance-endurance approach to chronic pain offer important ideas for
explanation and treatment.
Migräne und psychosomatische Komorbiditäten
Authors: Ruscheweyh Ruth , Lehnen Nadine , Henningsen Peter
Published: June 2024

Die Migräne als häufige neurologische Erkrankung (10-15% der Bevölkerung) ist mit
zahlreichen Komorbiditäten assoziiert, insbesondere mit anderen
Schmerzsyndromen, psychischen Erkrankungen und funktionellen Störungen. Diese
‚psychosomatischen‘ Komorbiditäten nehmen mit der Migräneschwere weiter zu.
Schwer betroffene, komorbide Patienten haben oft auch ein schlechteres
Ansprechen auf die spezifische Migränetherapie. Interessanterweise haben die
Migräne und die genannten Komorbiditäten zahlreiche gemeinsame ätiologische oder
begünstigende Faktoren, z.B. genetische Faktoren, das häufigere Vorkommen bei
Frauen und bei Menschen mit traumatischen Vorerfahrungen, sowie (bei
Schmerzsyndromen) Zeichen einer zentralen Sensibilisierung. Eine weitere
Gemeinsamkeit ist der Zusammenhang mit aktuellem oder chronischem Stresserleben.
Wir schlagen ein erweitertes Diathese-Stress-Modell vor, das zusammenhängende,
aber doch individuell unterschiedliche Vulnerabilitäten berücksichtigt und,
abhängig vom Stresserleben, sowohl das Auftreten einzelner Erkrankungen (z.B.
einer isolierten Migräne) als auch das gemeinsame Auftreten der Migräne mit
anderen Schmerzsyndromen und weiteren psychosomatischen Komorbiditäten abbilden
kann. Zusammenfassend sollten psychosomatische Begleiterkrankungen in der
Migränetherapie stets im Blick behalten und ggf. frühzeitig und multimodal
behandelt werden.
Tungsten-Catalyzed Regioselective Allylic Amination
Authors: Xu Wenbin
Published: June 2024

A highly regioselective synthesis of allylic amines based on a tungsten-catalyzed allylic amination has been developed. This protocol, which is catalyzed by commercially available W(CO)3(MeCN)3 and 4,4′-di-tert-butyl-2,2′-bipyridine, permits the formation of synthetically useful branched allylic N-aryl- and N-alkylamines in moderate to good yields with a >20:1 branched/linear ratio under mild conditions. The noble-metal-free catalytic system complements conventional allylic aminations catalyzed by an Ir or Rh complex.
α-Amino Acid Synthesis by 1,3-Nitrogen Migration: An Update
Authors: Meggers Eric , Yin Kuan
Published: June 2024

An improved practical and efficient procedure for the synthesis of non-racemic unnatural α-amino acids through a stereocontrolled rearrangement is reported. Carboxylic acids are converted into azanyl esters RCO2NHBoc followed by an iron-catalyzed 1,3-nitrogen migration to provide non-racemic α-amino acids in an asymmetric (α-monosubstituted α-amino acids) or enantioconvergent fashion (α,α-disubstituted α-amino acids). Under optimized conditions using a fluorinated chiral iron catalyst and 2,2,6,6-tetramethylpiperidine as the base in a solvent mixture of 1,2-dichlorobenzene and CHCl3, enantioselectivities of up to 98% ee were obtained. Such high ee values are important for practical purposes, allowing the direct use of many of the obtained N-Boc-protected α-amino acids for subsequent applications.
Effect of government expenditure on real economic growth in ECOWAS: assessing the moderating role of corruption and conflict
Authors: Okunlola Olalekan Charles , Sani Imran Usman , Ayetigbo Olumide Abiodun , Oyadeyi Olajide O.
Published: June 2024

This study investigated the effect of government expenditure on real growth in ECOWAS countries. This paper used panel cointegration techniques to examine the impact of government expenditure on economic growth for a sample of 15 ECOWAS countries between 1999 and 2021. The study uses the POLS, FMOLS, and DOLS techniques for estimating four models. The study supports the view that government expenditure positively affects real economic growth in ECOWAS countries. However, we also found that higher control of corruption improves the effectiveness and efficiency of government expenditure in promoting economic growth. Furthermore, a higher incidence of conflict minimizes the effectiveness and efficiency of government expenditure in promoting economic growth. The finding suggests that a well-managed government can contribute positively to economic growth. The finding that government expenditure positively affects real growth in ECOWAS countries suggests that a well-managed government can contribute positively to economic growth. This finding is helpful for policymakers in ECOWAS countries interested in improving their countries’ economic growth.
Highly selective and sensitive detection of volatile organic compounds using long wavelength InAs-based quantum cascade lasers through quartz-enhanced photoacoustic spectroscopy
Authors: Kinjalk Kumar , Paciolla Francesco , Sun Bo , Zifarelli Andrea , Menduni Giansergio , Giglio Marilena , Wu Hongpeng , Dong Lei , Ayache Diba , Pinto Davide , Vicet Aurore , Baranov Alexei , Patimisco Pietro , Sampaolo Angelo , Spagnolo Vincenzo
Published: June 2024

The precise detection of volatile organic compounds plays a pivotal role in addressing environmental concerns, industrial safety, and medical diagnostics. The accurate identification and quantification of these compounds because of their ubiquity and potential health hazards has fueled the development of advanced sensing technologies. This work presents a sensing system in the realm of long-wavelength infrared spectroscopy for achieving enhanced selectivity and sensitivity of benzene, toluene, and propane detection through quartz-enhanced photoacoustic spectroscopy. High-resolution gas spectroscopy is made possible by the use of specially designed InAs/AlSb-based quantum cascade lasers, emitting in the wavelength range 13–15 μm, and quartz tuning forks. The sensor system, characterized by its robustness and precision, demonstrates exceptional capabilities in benzene, toluene, and propane detection. The system's capacity for practical applications in environmental monitoring and medical diagnostics is demonstrated by its ability to distinguish these volatile organic compounds with a minimum detection limit of 113 ppb, 3 ppb, and 3 ppm for toluene, benzene, and propane at an integration time of 10 s, even in complex gas matrices. This work advances gas sensing technology while also offering insightful information on spectral interferences, a persistent problem in the field. The results usher in a new era of sophisticated and reliable gas sensing techniques meeting the growing demand for precise volatile organic compounds detectors for environmental monitoring purposes.
Structural effects on thermal conductivity of micro-thick Li4Ti5O12-based anode
Authors: Rahbar Mahya , Wang Ying , Xu Shen , Cheng Wenlong , Wang Xinwei
Published: June 2024

This study investigates the structural effects on the cross-plane thermal conductivity of Li4Ti5O12-based anode active material. Three structures are investigated: a basic structure consisting of LiBr/LiCl/Li4Ti5O12, polyvinylidene difluoride, and Super P (sample #1); a structure without Li4Ti5O12 (sample #2); and a structure without LiBr/LiCl (sample #3). Despite its high porosity level (77%), sample #1 exhibits higher thermal conductivity than sample #3 (64% porosity) in both air and vacuum conditions, potentially due to the extra structural bonding provided by LiBr/LiCl. The observed difference in cross-plane thermal conductivity between air and vacuum conditions provides insights into the configuration of the anode's active material in the heat transfer direction. The lower limit corresponds to the parallel thermal circuit configuration of active material and air, which is the product of the sample's porosity and thermal conductivity of air. Our analysis suggests that in sample #2, the anode's active material and air inside the pores demonstrate a more serial configuration, while in sample #3, they exhibit a more parallel configuration in the heat transfer direction. However, the thermal conductivity difference observed for sample #1 falls below the theoretical lower bound indicating significant thermal radiation within the pores. Furthermore, the in-plane thermal conductivity is predominantly controlled by the copper foil. Sample #2 exhibits the lowest in-plane thermal conductivity. This is attributed to the severe oxidization of the copper foil by LiBr/LiCl, which is confirmed by structure characterization.
High-order harmonic generation in liquid crystals
Authors: Annunziata Andrea , Becker Luise , Murillo-Sánchez Marta L. , Friebel Patrick , Stagira Salvatore , Faccialà Davide , Vozzi Caterina , Cattaneo Laura
Published: June 2024

Thermotropic liquid crystals are versatile optical materials that exhibit a state of matter intermediate between liquids and solids. Their properties can change significantly with temperature, pressure, or other external factors, leading to different phases. The transport properties within these materials in different phases are still largely unexplored, and their understanding would enable exciting prospects for innovative technological advancements. High-order harmonic spectroscopy proved to be a powerful spectroscopic tool for investigating the electronic and nuclear dynamics in matter. Here, we report the first experimental observation of high-order harmonic generation in thermotropic liquid crystals in two different phase states, nematic and isotropic. We found the harmonic emission in the nematic phase to be strongly dependent on the relative orientation of the driving field polarization with respect to the liquid crystal alignment. Specifically, the harmonic yield has a maximum when the molecules are aligned perpendicularly to the polarization of the incoming radiation. Our results establish the first step for applying high-order harmonic spectroscopy as a tool for resolving ultrafast electron dynamics in liquid crystals with unprecedented temporal and spatial resolution.
High-voltage AlGaN/GaN heterojunction lateral photoconductive semiconductor switch based on semi-insulating 4H-SiC substrate
Authors: Li Yangfan , Xiao Longfei , Luan Chongbiao , Qin Yan , Sun Xun , Sha Huiru , Jiao Jian , Chen Xiufang , Li Hongtao , Xu Xiangang
Published: June 2024

A novel high-power AlGaN/GaN heterojunction lateral photoconductive semiconductor switch (PCSS) based on the SiC substrate is proposed, which achieves high dark-state resistance characteristics by groove etching. Under the action of biased electric field and incident laser, a high concentration of two-dimensional electron gas is formed at the heterojunction interface. The photo-generated free carriers transport along the heterojunction interface, which improves the utilization efficiency of photo-generated carriers. Moreover, the simulation of the current density distribution of the PCSS provides theoretical support for this phenomenon. Compared with the conventional GaN PCSS, the power capacity and conduction characteristics are further improved. The test results show that the output current of the device increases significantly after the introduction of the AlGaN/GaN heterojunction. At the biased voltage of ∼34 kV, the maximum output current of the AlGaN/GaN PCSS reaches 205 A.
Study on velocity profile of gas–liquid two-phase stratified flow in pipelines based on transfer component analysis-back propagation neural network
Authors: Liu Xu , Song Yingrui , Zhao Danlei , Lan Kang , Zhai Ke , Wang Mi , Fang Lide
Published: June 2024

The measurement of cross-sectional velocity profile is a challenge in the field of two-phase flow. In this paper, the stereoscopic particle image velocimetry (SPIV) technique is employed to obtain the cross-sectional velocity profile of gas and liquid phase in stratified flow. Interface velocity profile is obtained through numerical simulation. By leveraging the concept of transfer learning, we propose to construct a transfer component analysis-back propagation network using stereo particle image velocimetry and numerical simulation and to predict the velocity profile of the gas–liquid interface in stratified flow. The research indicates that the cross-sectional velocity profile of the gas–liquid stratified flow is similar to the “mushroom” shape. The velocity profile of the gas–liquid interface changes from an M-type to the N-type, and the gas–liquid velocity slip affects the transformation process. With the increase in the gas-phase velocity, the distance between the two peaks of the M-type velocity profile increases and the gap between gas–liquid velocity peaks increases accordingly.
Enhancing performance of Au-hyperdoped Si photodetectors for infrared detection
Authors: Liu Yining , Yang Wenjie , Hudspeth Quentin , Sarangan Andrew , Agha Imad , Williams James S. , Warrender Jeffrey M. , Mathews Jay
Published: June 2024

Hyperdoping Si with transition metals to form intermediate bands for infrared absorption has attracted attention recently for producing sub-bandgap photoconductivity. In particular, Si hyperdoped with Au has been demonstrated to exhibit optoelectronic response at 1550 nm. However, the reported external quantum efficiencies (EQEs) are low, and the device fabrication processes had not been optimized. In this paper, we demonstrate a significant improvement in sub-bandgap EQE through modification of the material and device fabrication processes. By increasing the Si:Au layer thickness, modification of device design, and formation of Ohmic contacts, the EQE was measured to be as high as 0.44% at 1550 nm, nearly two orders of magnitude higher than previous reports from similar devices. Additionally, the EQE was measured to be in the 10-3 range for wavelengths as long as 2.4 μm. The EQE spectrum showed features that were attributed to defect levels from a substitutional Au acceptor defect. The above bandgap EQE showed gain in one device. Thermal annealing at 300 °C does not improve the efficiency of Si:Au photodiodes. These results demonstrate the viability of Au-hyperdoped Si for infrared detection below the bandgap of Si.
Enhancing model identification with SINDy via nullcline reconstruction
Authors: Prokop Bartosz , Frolov Nikita , Gelens Lendert
Published: June 2024

Many dynamical systems exhibit oscillatory behavior that can be modeled with differential equations. Recently, these equations have increasingly been derived through data-driven methods, including the transparent technique known as Sparse Identification of Nonlinear Dynamics (SINDy). This paper illustrates the importance of accurately determining the system’s limit cycle position in phase space for identifying sparse and effective models. We introduce a method for identifying the limit cycle position and the system’s nullclines by applying SINDy to datasets adjusted with various offsets. This approach is evaluated using three criteria: model complexity, coefficient of determination, and generalization error. We applied this method to several models: the oscillatory FitzHugh–Nagumo model, a more complex model consisting of two coupled cubic differential equations with a single stable state, and a multistable model of glycolytic oscillations. Our results confirm that incorporating detailed information about the limit cycle in phase space enhances the accuracy of model identification in oscillatory systems.
Data-driven modeling of equatorial atmospheric waves: The role of moisture and nonlinearity on global-scale instabilities and propagation speeds
Authors: Teruya André S. W. , Raphaldini Breno , Raupp Carlos F. M. , Peixoto Pedro S. , Mayta Victor C. , Silva-Dias Pedro L.
Published: June 2024

The equatorial region of the Earth’s atmosphere serves as both a significant locus for phenomena, including the Madden–Julian Oscillation (MJO), and a source of formidable complexity. This complexity arises from the intricate interplay between nonlinearity and thermodynamic processes, particularly those involving moisture. In this study, we employ a normal mode decomposition of atmospheric reanalysis ERA-5 datasets to investigate the influence of nonlinearity and moisture on amplitude growth, propagation speed, and mode coupling associated with equatorially trapped waves. We focus our analysis on global-scale baroclinic Kelvin and Rossby waves, recognized as crucial components contributing to the variability of the MJO. We examine the dependence of wave amplitudes on the background moisture field in the equatorial region, as measured by total column water vapor. Our analysis demonstrates the crucial role of moisture in exciting these waves. We further investigate the dependence of the propagation speed of the waves on their amplitudes and the background moisture field. Our analysis reveals a robust correlation between the phase speed of the normal modes and their corresponding amplitude, whereas a weaker correlation is found between the eigenmodes’ phase speed and the moisture field. Hence, our findings suggest that moisture plays a role in exciting the global-scale Rossby–Kelvin structure of the MJO. In this context, the propagation speed of the eigenmodes is mainly influenced by their amplitudes, underscoring the significant role of nonlinearity in wave propagation.
Physical mechanism underlying the enhancement effect of carbon in heavily phosphorus-doped Czochralski silicon substrate on phosphorus out-diffusion within n/n+ epitaxial wafer
Authors: Li Shenzhong , Zhao Tong , Wu Defan , Liang Xingbo , Chen Hao , Nie Qunlin , Tian Daxi , Ma Xiangyang , Yang Deren
Published: June 2024

The effects of carbon in heavily phosphorus-doped Czochralski (HP-Cz) silicon (Si) substrates, with the concentrations across an order of magnitude from 1016 to 1017 cm−3, on the out-diffusion of phosphorus impurities within n/n+ epitaxial Si (Epi-Si) wafers have been investigated. It is found that the increase in the carbon concentration ([C]) from 1.0 × 1016 to 1.0 × 1017 cm−3 leads to the enhanced phosphorus out-diffusion within the n/n+ Epi-Si wafer when subjected to anneal at 1100 °C in an N2 or an O2 ambient or to anneal at 1150 °C in an N2 ambient, but hardly affects the phosphorus out-diffusion within the n/n+ Epi-Si wafer when subjected to anneal at 1150 °C in an O2 ambient. Based on the density functional theory calculations, it is derived that the increase in the [C] from 1.0 × 1016 to 1.0 × 1017 cm−3 in the HP-Cz Si substrate results in a significantly increased thermal equilibrium concentration of self-interstitial silicon (SiI) atoms at 1100 or 1150 °C, which, in turn, leads to the increased concentration of the SiI atoms that out-diffuse from the substrate to the epitaxial layer because the SiI atoms diffuse extremely fast in Si. Such a carbon-induced increase in the concentration of SiI atoms is believed to be responsible for the aforementioned enhanced phosphorus out-diffusion, which is predominantly dictated by the interstitialcy mechanism. In the case of anneal in the O2 ambient at sufficiently high temperatures such as 1150 °C, a large number of excessive SiI atoms injected into the Epi-Si wafer substantially mask the carbon enhancement effect on the phosphorus out-diffusion. Of technological significance, it is deduced that the [C] should be not higher than 1.0 × 1016 cm−3 in the HP-Cz Si wafers as the substrates of n/n+ Epi-Si wafers used for power devices.
Hemodynamic coupling between a primary atherosclerotic plaque and subsequent secondary lesions
Authors: Nooraeen Ahmad , Taghizadeh Hadi , Ghalichi Farzan
Published: June 2024

Atherosclerosis is one of the most common diseases of the arterial tree, especially in the coronary arteries. Stenoses exceeding 50% area reduction are shown to alternate the downstream coronary flow, and hemodynamics will lead to further atherogenesis. Clinical evidence also confirms that vascular stenoses are not stagnant since they are usually associated with downstream lesions. In this study, it is hypothesized that the formation of secondary plaques, or aneurysms downstream of a primary stenosis, compensates for the abnormal ranges of hemodynamic forces caused by the primary stenosis. An experimental setup captured the hemodynamics of non-Newtonian blood flow in three-dimensional (3D) printed phantoms of coronary arteries with various sequences of lesions. Then, based on the collected data, in silico models of these lesions were simulated using computational fluid dynamics. For the proposed cases, time-averaged wall shear stress, velocity profile, oscillatory shear index, and relative residence time were extracted at the plaque side and the plaque front walls and compared to the reference model with only the primary plaque. The secondary plaque postulated the abnormal hemodynamic conditions to its downstream, which implies endothelial activation and onset of further pathologic events. However, the secondary aneurysm restored flow conditions to normal after its distal shoulder, preventing more damage to the endothelium. Examined angiograms of patients with developed atherosclerotic lesions unveiled that a sequence of plaques is formed over time, and most interestingly, the series stopped after the formation of an aneurysm.
Quantitative study of oxygen evolution reaction using LiNi0.5Mn1.5O4 thin-film electrodes
Authors: Hatagami Kentaro , Nishio Kazunori , Shimizu Ryota , Hitosugi Taro
Published: June 2024

The development of water electrolysis catalysts that accelerate the oxygen evolution reaction (OER) is a crucial challenge. Ni-based oxides are promising OER catalysts; however, quantitative studies of Ni-based oxides remain unexplored. In this study, we quantitatively evaluated the OER activity of LiNi0.5Mn1.5O4 as a thin-film electrode catalyst. The LiNi0.5Mn1.5O4 thin film fabricated using a sputtering method exhibited a current density of 6.6 and ∼2.6 mAcm−2 for geometric and estimated areas, respectively, at 1.78 V vs. a reversible hydrogen electrode. X-ray photoelectron spectroscopy indicated the presence of Ni3+ in the as-grown and post-OER LiNi0.5Mn1.5O4 thin films. These results suggest that Ni3+ plays a key role in the OER of LiNi0.5Mn1.5O4.
Advances in chalcogenide perovskites: Fundamentals and applications
Authors: Han Yanbing , Fang Xiaosheng , Shi Zhifeng
Published: June 2024

Chalcogenide perovskites are a family of compounds related to perovskite structures or compositions, which have witnessed rapid advances in recent years. They possess favorable properties such as high stability, low toxicity, direct band gaps, good carrier transport abilities, strong light absorption, and potential luminescent properties, making them stand out in emerging applications, such as photovoltaics, photodetectors, light-emitting devices, and photocatalysts, among others. In this review, we aim to provide a comprehensive overview of the properties, synthesis, and applications of chalcogenide perovskites. First, we first survey the reported material structures/compositions and current understanding of their structural/optical/electrical properties, mechanics, magnetics, and stabilities. Furthermore, we discuss the synthesis strategies of these materials covering various material types such as powders, pellets, thin films, nanocrystals, and single crystals, with a focus on their potential applications, including photovoltaics, photodetectors, and other devices. Finally, we outline a brief conclusion and some prospects for the further research of chalcogenide perovskites, thus promoting more studies and developments in this field. This review can provide new insights into the fundamental properties and potential applications of chalcogenide perovskites, and thereby facilitating their further studies and developments.
Influence of a transverse magnetic field on wakefield oscillations around a charged dust grain in complex plasma
Authors: Dutta Biswajit , Gogoi Niranjan , Das Nilakshi
Published: June 2024

In the presence of ion streaming, the potential around dust particles immersed in plasma becomes anisotropic. In this scenario, the repulsive Debye–Hückel potential is superimposed with an attractive wake potential. This work presents an analytical study of the complex behavior of such a wake potential in the presence of a magnetic field (oriented transversely to the ion flow) and ion-neutral collisions using linear response formalism, both in subsonic and supersonic regimes. The amplitude and periodicity of this potential are found to be controlled by the interplay among ion streaming velocity, ion cyclotron frequency, and ion-neutral collision frequency. Due to the tunable nature of this potential, it is possible to control the crystal formation, phase transitions, and transport properties of dusty plasma by adjusting the external magnetic field. The study also reveals that the wake potential almost disappears in a collision-dominant regime.
Uniaxial compressive creep tests by spark plasma sintering of 70% theoretical density α-uranium and U-10Zr
Authors: Fay Jake , Lemma Fidelma Di , Capriotti Luca , Zhao Dong , Benson Michael T. , Medvedev Pavel , Lian Jie
Published: June 2024

Metallic fuels hold numerous advantages over conventional uranium dioxide fuels and are a key component of several liquid metal-cooled advanced reactor concepts including sodium fast reactors. These fuels undergo rapid swelling during early burnup; consequently, they spend most of their reactor lifetime in a porous state. The presence of this porosity alters many of the mechanical properties of the fuel including creep impacting fuel deformation during axial swelling. This work investigates the creep behavior of the porous fuel using a spark plasma sintering technique. Creep tests were performed for the first time on porous α-phase uranium and uranium with 10 wt. % zirconium (U-10Zr) samples. The samples of α-phase uranium and U-10Zr were fabricated from depleted uranium by spark plasma sintering and subjected to uniaxial compressive creep testing. Calculated stress exponents were found to be 2.6±1.6 and 5.7±1.4 for α-U and U-10Zr, respectively, and calculated activation energies were found to be 61.6±1.1kJ/mol for α-U. The creep data were also used to evaluate existing porosity inclusive in creep models.
Effects of the wall temperature on separation flowfield of swept shock wave/boundary layer interactions
Authors: Zhou Yong-yi , Zhao Yi-long , Zhao Yu-xin , Zhong Jia-cheng , He Gang
Published: June 2024

Swept shock wave/boundary layer interaction (SWBLI) is a complex flow phenomenon commonly observed in three-dimensional hypersonic inlets. Wall temperatures can influence the scale of the separation of the swept SWBLI. It may lead to inlets unstart, resulting in a significant decrease in mass flow rate. This study delves into the flowfield of swept SWBLI under varying wall temperatures, using both experimental and numerical methods to examine the effects of these temperature changes on the separation scaling and the fluctuating velocity within the SWBLI flowfield. The investigation uncovers that modifications in wall temperature significantly impact the boundary layer's subsonic layer thickness, streamwise momentum distribution, and shear stress, which collectively alter the separation scale. To estimate characteristic surface limiting streamline angles under changed wall temperature conditions, a predictive model is proposed that utilizes the boundary layer shape factor H as a metric. Additionally, it is established that wall temperature variations can influence surface friction coefficients, which can, in turn, affect the pressure rise process during separation and alter the spatial angle of the separation shock. The fluctuating velocity characteristic reveals that the wall temperature affects the separated flow mainly on the incoming boundary layer.
Active gas camera mass flow quantification (qOGI): Application in a biogas plant and comparison to state-of-the-art gas cams
Authors: Bergau M. , Scherer B. , Knoll L. , Wöllenstein J.
Published: June 2024

Gas cameras are primarily used to detect gas leaks, but their use has been increasingly extended to mass flow quantification (qOGI). We employ the previously published active illuminated gas camera [Bergau et al. “Real-time active-gas imaging of small gas leaks,” J. Sens. Sens. Syst. 12, 61–68 (2023) and Bergau et al. “Flow rate quantification of small methane leaks using laser spectroscopy and deep learning,” Process Saf. Environ. Prot. 182, 752–759 (2024)] in a real-world application for quantification, enhancing the camera with two new features: sensitivity adaptation and camera-gas distance detection. This technology was applied to a gas leak found in the pressure swing adsorption room of a biogas plant in Germany. We compare its performance with state-of-the-art quantification gas cameras (qOGI), such as Sensia Mileva 33. Such a comparison between active and passive gas cameras is possible for the first time due to the introduced sensitivity tuning. Additionally, we enclosed the gas leak and measure the methane concentration with a flame ionization detector, providing a gold standard for comparison. Our findings revealed relative offsets to our gold standard of −57% and +319% for the DAS-camera and the Sensia, respectively, suggesting that the accuracy of mass flow quantification could be improved through the use of active gas cameras.
Influence of contraction ratio on electroviscous flow through the slit-type non-uniform microfluidic device
Authors: Dhakar Jitendra , Bharti Ram Prakash
Published: June 2024

The electroviscous effects are relevant in controlling and manipulating the fluid, thermal, and mass transport microfluidic processes. The existing research has mainly focused on the fixed contraction ratio (dc, i.e., the area ratio of contraction to expansion) concerning the widely used contraction–expansion geometrical arrangement. This study has explored the influence of the contraction ratio (dc) on the electroviscous flow of electrolyte liquids through the charged non-uniform microfluidic device. The numerical solution of the mathematical model (Poisson's, Nernst–Planck, and Navier–Stokes equations) using a finite element method yields the local flow fields. In general, the contraction ratio significantly affects the hydrodynamic characteristics of microfluidic devices. The total electrical potential and pressure drop maximally change by 1785% (from −0.2118 to −3.9929) and 2300% (from −0.0450 to −1.0815), respectively, as the contraction ratio (dc) varies from 1 to 0.25. Furthermore, an electroviscous correction factor (Y, i.e., the ratio of apparent to physical viscosity) maximally enhances by 11.24% (at K = 8, S = 16 for 0.25≤dc≤1), 46.62% (at S = 16, dc=0.75 for 20≥K≥2), 22.89% (at K = 2, dc=0.5 for 4≤S≤16), and 46.99% (at K = 2, dc=0.75 for 0≤S≤16). Thus, the electroviscous effect is obtained maximum at dc=0.75 for the considered ranges of conditions. Finally, a pseudo-analytical model has been developed for a charged microfluidic device with variable contraction size (0.25≤dc≤1), based on the Hagen–Poiseuille flow in the uniform slit, which calculated the pressure drop within ±3% of the numerical results. The present numerical results may provide valuable guidelines for the performance optimization and design of reliable and essential microfluidic devices.
Calculation model of rectangular-like Herriott cell based on folded-optics method
Authors: Tian Qingyuan , Wu Hongpeng , Cui Ruyue , Hu Yongyong , Xue Yan , Wang Gang , Wang Jiapeng , Wang Yong , Liu Xiaoli , Tittel Frank K. , Dong Lei
Published: June 2024

We present a calculation model for rectangular-like Herriott cells (RLHCs), in which a long cylindrical traditional Herriott cell (HC) is transformed into a rectangular-like configuration by introducing two highly reflective plane mirrors. The position formula for two spheric mirrors and two plane mirrors is provided to precisely define the RLHC. The folding effects of RLHCs with 1–8-times folding are evaluated in terms of the cell length, the cell volume, and the total number of reflections. The proposed folded-optics method significantly enhances the utilization efficiency of the mirror surfaces, resulting in a reduction of both physical length and volume when compared to a traditional HC. Importantly, this reduction is achieved while maintaining the same optical path length, and all of these advantages come at a low cost.
Bubble rising in the presence of a surfactant at very low concentrations
Authors: Rubio A. , Vega E. J. , Cabezas M. G. , Montanero J. M. , López-Herrera J. M. , Herrada M. A.
Published: June 2024

This paper analyzes experimentally and numerically the steady bubble rising in water with a surfactant dissolved at very low concentrations. We explain how traces of surfactant can significantly change the bubble dynamics. The tiny surface tension variation produced by the surfactant monolayer has a negligible effect on the capillary pressure. However, this variation occurs within an extremely thin diffusive boundary layer, which produces a Marangoni stress three orders of magnitude larger than the tangential viscous stress in a surfactant-free bubble. Although the Marangoni stress is confined within the surface boundary layer, it manages to immobilize most of the bubble's south hemisphere. The increase in skin friction and the reduction of the terminal velocity cannot be attributed to the viscous stress exerted on the immobilized interface but to the stress in the diffusive surface boundary layer. The stagnant-cap approximation applies despite the small surfactant concentration considered.
On the grain size effects of the spallation in Pb by quasi-coarse-grained molecular dynamics
Authors: Wang Haijin , Li Run , Gao Yibo , Huang Yongfeng , Xiao Shifang , Li Xiaofan , Wang Kun
Published: June 2024

FCC-HCP phase transition plays a pivotal role in many intelligent materials, which also occurs in Pb under high pressures. However, its impacts on the spallation of polycrystalline, as well as the effects related to grain size, are still unclear. In this work, spallation behaviors of Pb polycrystals with different grain sizes under various shock loadings are investigated using the quasi-coarse-grained molecular dynamics (QCGD) method based on our recently developed response embedding atom model potential. The QCGD method is rigorously validated for applications in the metals exhibiting solid–solid phase transitions. Due to the restriction of the critical size for the phase transition nucleus, the coarsening level of the QCGD method cannot exceed two times the lattice parameter. Nevertheless, such a method enables us to explore the whole rule of the grain-size-dependence incipient spall strength. Our results suggest that the incipient spall strength exhibits a transition from the Hall–Petch to the inverse Hall–Petch relationship at about 13 nm and the spallation strength converging to that of a single crystal for grain sizes larger than 60 nm. As the grain size decreases, void nucleation becomes more prevalent than void growth, making the material better equipped to prevent the progression of damage into fractures. When the grain size is sufficiently large, voids nucleate and grow in the grain interior, making the spallation behave like in a single crystal. Interestingly, the phase transition from HCP to FCC phase enhances dislocation entanglement, leading to heterogeneous nucleation of voids in the grain interior.
Modeling thermocapillary microgear rotation and transferring the concept of asymmetric shape to translational particle propulsion
Authors: Carl Tillmann , Schönecker Clarissa
Published: June 2024

In this study, we investigate the thermocapillary rotation of microgears at fluid interfaces and extend the concept of geometric asymmetry to the translational propulsion of micrometer-sized particles. We introduce a transient numerical model that couples the Navier–Stokes equations with heat transfer, displaying particle motion through a moving mesh interface. The model incorporates absorbed light illumination as a heat source and predicts both rotational and translational speeds of particles. Our simulations explore the influence of microgear design geometry and determine the scale at which thermocapillary Marangoni motion could serve as a viable propulsion method. A clear correlation between Reynolds number and rotation efficiency can be recognized. To transfer the asymmetry-based propulsion principle from rotational to directed translational motion, various particle geometries are considered. We demonstrate that, under illumination from above, geometrically asymmetric “Christmas tree”-shaped particles move forward. The exploration of breaking geometric symmetry for translational propulsion is mostly ignored in the existing literature, thus warranting further discussion. Therefore, we analyze expected translational speeds in comparison to corresponding microgears to provide insight into this promising propulsion method. Our simulations indicate that translational propulsion speeds of several particle lengths per second can be expected on the micrometer scale.
TDDFT and the x-ray absorption spectrum of liquid water: Finding the “best” functional
Authors: Fransson Thomas , Pettersson Lars G. M.
Published: June 2024

We investigate the performance of time-dependent density functional theory (TDDFT) for reproducing high-level reference x-ray absorption spectra of liquid water and water clusters. For this, we apply the integrated absolute difference (IAD) metric, previously used for x-ray emission spectra of liquid water [T. Fransson and L. G. M. Pettersson, J. Chem. Theory Comput. 19, 7333–7342 (2023)], in order to investigate which exchange–correlation (xc) functionals yield TDDFT spectra in best agreement to reference, as well as to investigate the suitability of IAD for x-ray absorption spectroscopy spectrum calculations. Considering highly asymmetric and symmetric six-molecule clusters, it is seen that long-range corrected xc-functionals are required to yield good agreement with the reference coupled cluster (CC) and algebraic-diagrammatic construction spectra, with 100% asymptotic Hartree–Fock exchange resulting in the lowest IADs. The xc-functionals with best agreement to reference have been adopted for larger water clusters, yielding results in line with recently published CC theory, but which still show some discrepancies in the relative intensity of the features compared to experiment.
Polarized neutron imaging at NeXT (neutron and x-ray tomograph) at Institut Laue Langevin
Authors: Oji U. K. , Tengattini A. , Helfen L. , Manke I. , Cubitt R. , Kardjilov N.
Published: June 2024

This work describes the implementation of polarized neutron imaging capabilities at the neutron and x-ray tomograph (NeXT) imaging station of the Institut Laue Langevin. This development enhances the capacity of this instrument to study advanced magnetic materials, which are crucial in a variety of engineering applications. Here, the feasibility of polarized neutron imaging at NeXT is demonstrated by visualizing the magnetic field generated by a simple bar magnet. The use of a double-crystal monochromator for wavelength-resolved imaging is also shown to enable both quantitative and qualitative analyses of magnetic materials. This is demonstrated through the determination of magnetization strength in a sample of electric steel (FeSi) in addition to the distribution of its components. Polarimetric imaging is also implemented for the first time to characterize the magnetic field generated by a current-carrying cylindrical wire. These findings collectively underscore the value of incorporating polarized neutron imaging into the already cutting-edge imaging station.
Formation of basal plane dislocations by stress near epilayer/substrate interface of large-diameter SiC wafers with thick epitaxial layers
Authors: Fujie Fumihiro , Shiono Tsubasa , Murata Koichi , Ishibashi Naoto , Mabuchi Yuichiro , Tsuchida Hidekazu
Published: June 2024

For large-diameter (150 mm) SiC epitaxial wafers with thick n− epilayers, stress analysis based on the finite element method and defect characterization near the epi/sub interface by synchrotron x-ray topography were performed. Observations on epitaxial wafers with epilayer thicknesses of 10, 20, 50, and 100 μm revealed that basal plane dislocation (BPD) half-loops were formed near triangular defects or from the edge of the wafer at an epilayer thickness of 50 μm and above. Two types of BPD half-loops with different edge components were observed: one with an extra half-plane above the core and present on the substrate side, and the other with a Burgers vector of opposite sign and present in the epilayer and at the epi/sub interface, forming an interfacial dislocation. The signs of these BPDs are consistent with those predicted from the calculation results, which mitigate compressive and tensile stresses in the epilayer and the substrate, respectively. It is considered that a thicker epilayer increases tensile stress in the substrate, which induces the formation of the BPD with an extra half-plane above the core on the substrate side. The distribution of the BPD half-loop width was also analyzed and compared with the calculated shear stress distribution caused by the radial temperature gradient. Calculations considering the local stress near the triangular defect revealed that the tensile stress near the epi/sub interface locally increases, exceeding the critical stress to form BPD, with an extra half-plane above the core for wafers with an epilayer thickness above 50 μm.
Experimental investigation of the flow-induced vibration of a hybrid riser conveying severe slugging
Authors: Zhu Hongjun , Li Yang , Song Jinze , Liu Peng , Zhou Mai , Zhou Tongming
Published: June 2024

This paper reports the experimental results of the vibration response of a hybrid riser conveying severe slugging. The hybrid riser comprises a vertical rigid riser made of a transparent acrylic tube and a flexible jumper made of a transparent silica gel tube with a length to internal diameter ratio of 261. The horizontal span and vertical height of the flexible jumper are 83.5 and 45 cm, respectively. The flow-induced vibration tests were carried out in the liquid superficial velocity range of Vsl = 0.098–0.688 m/s and the gas superficial velocity range of Vsg = 0.177–0.649 m/s using non-intrusive optical measurement with high-speed cameras. Five flow regimes are observed, including the severe slugging I (SSI), severe slugging II (SSII), severe slugging III (SSIII), stable flow (ST), and oscillation flow regimes. The vibration response of the flexible jumper is related to the flow regime. As the flow regime changes from SSI to SSII, the absence of the slug production stage results in an augmented amplitude. In contrast, the response amplitude is significantly reduced when the flow regime shifts to ST. For the SSI regime, the response amplitude varies over the stage, and the occurrence of multiple frequencies is associated with the pressure fluctuation as well as the different duration of stages. The maximum amplitude is observed in the liquid fallback stage in spite of the limited duration, and the vibration frequency is close to the fundamental natural one. The liquid slugs of different lengths passing through the jumper at different velocities contribute to the presence of the traveling wave characteristic.