bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic optimisation of the rail track by targeted variation of continuous superstructure parameters along the track
Authors: Mantel Maximilian , Stampka Katja , Sarradj Ennes
Published: November 2024

Rolling noise is the dominant source for railway vehicles at medium train speeds. In order to reduce the contribution radiated by the rail, this paper investigates how structural irregularities affect sound propagation by varying the superstructure properties along a ballasted track. The so-called disorder is therefore used to optimise the track decay rate (TDR) and thus achieve a lower mean square velocity of the rail. Track parameters included in the analysis are the pad stiffness, the sleeper mass and the sleeper spacing. Structure-borne sound propagation in the rail is computed using a fast finite-difference method. Both periodically repeating and stochastically distributed variations are considered for parameter variation along the track, with up to three parameters being varied simultaneously. The most promising variation schemes are identified with the help of parameter optimisation using the brute-force method. It has been shown that a high TDR over a wider frequency range and a lower TDR drop in the pinned-pinned frequency range can be achieved due to the presence of disorder. The study indicates that variations of the superstructure parameters along the track are a promising method in order to reduce track vibration levels.
L’actionnabilité clinique des gènes
Authors: Pion Emmanuelle , Bonne Gisèle , Atalaia Antonio , Salort-Campana Emmanuelle , Gorokhova Svetlana , Attarian Shahram , Cossée Mireille , Krahn Martin
Published: November 2024

Le séquençage à haut débit a introduit le concept de « gènes actionnables ». Ces gènes sont liés à des pathologies pour lesquelles des traitements ou des prises en charge spécifiques existent. Un diagnostic génétique précis est donc crucial pour initier des interventions précoces qui peuvent prévenir ou retarder l’évolution de maladies rares. Le séquençage à haut débit a considérablement augmenté les capacités d’analyse génétique, mais il a également entraîné une augmentation des demandes d’analyses, allongeant les délais de rendu des résultats. Une priorisation des analyses devient nécessaire, surtout lorsque des « gènes actionnables » sont suspectés. Pour les myopathies, un travail national a identifié 63 gènes actionnables, impliqués dans des pathologies pour lesquelles peuvent être initiés un traitement ciblé et/ou une prise en charge précoce, améliorant ainsi le pronostic des patients. Malgré des avancées, de nombreuses maladies rares restent sans traitements spécifiques, soulignant l’importance continue de la recherche et de l’innovation en génétique médicale.
Contrôles des paramètres des domaines nucléaires par les microtubules et la protéine MACF1
Authors: Ghasemizadeh Alireza , Gache Vincent
Published: November 2024

Les fibres du muscle squelettique sont des syncytia formés par la fusion de dizaines ou centaines de cellules progénitrices mononucléées. Au cours de la myogenèse, les noyaux arrivant des cellules progénitrices parcourent un long chemin avant d’être positionnés à la périphérie d’une myofibre mature. Une fois à la périphérie, ces noyaux sont régulièrement espacés et chacun est transcriptionnellement responsable de sa proportion de cytoplasme environnant, connue comme « domaine nucléaire ». La perturbation de ces domaines peut être observée dans différentes myopathies, suggérant leur importance pour la fonctionnalité du muscle squelettique. Cependant, les mécanismes régulant la stabilité des domaines nucléaires sont mal connus. Nous prenons ici l’exemple de MACF1, une protéine associée aux microtubules, comme une actrice essentielle dans l’organisation des domaines nucléaires, afin de mettre en lumière le rôle potentiel des microtubules et de leur réseau protéique associé pour la stabilité de ces domaines et donc pour la fonctionnalité des myofibres.
Effets de l’exercice physique sur les maladies musculaires
Authors: Boulinguiez Alexis , Bouragba Dounia , Crisol Barbara , Bigot Anne , Butler-Browne Gillian , Trollet Capucine
Published: November 2024

Les myopathies constituent un groupe hétérogène de maladies caractérisées par une faiblesse et une dégénérescence progressive des muscles. Alors que ces maladies impactent fortement la qualité de vie des patients, de plus en plus d’études précliniques et cliniques suggèrent que des exercices physiques adaptés sont bénéfiques pour atténuer certains symptômes et améliorer plusieurs paramètres fonctionnels. Cette brève revue de la littérature évoque l’avancée actuelle des recherches sur les effets de l’exercice physique chez l’Homme dans diverses maladies musculaires, en explorant son impact sur les mécanismes moléculaires, la force, l’endurance, la fonction musculaire et la qualité de vie.
A new modeling approach of Myxococcus xanthus bacteria using polarity-based reversals
Authors: Bloch Hélène , Calvez Vincent , Gaudeul Benoît , Gouarin Loïc , Lefebvre-Lepot Aline , Mignot Tâm , Romanos Michèle , Saulnier Jean-Baptiste
Published: November 2024

The aim of this paper is to model the collective behavior of Myxococcus xanthus bacteria to better understand the emerging patterns at the level of the colony. We use image analysis and data treatment on experimental data of Myxococcus xanthus bacteria. We develop two models whose main novelty is the polarity-based reversals. The first model is based on contact dynamics approach and the second one is inspired by a molecular dynamics approach. We compare the two models and we show numerical simulations in 2D. The mathematical and biological aspects of each model are discussed.
Reducing the memory usage of structured grid solvers with wavelet compression
Authors: Flint Clément , Helluy Philippe
Published: November 2024

This paper presents a new solution to address the challenge of increasing memory usage in high-performance computing simulations on structured grids. Our approach utilizes a lossy compression scheme based on the Discrete Wavelet Transform (DWT) to achieve high compression ratios while preserving the accuracy of the simulation. Our evaluation on a finite volume scheme demonstrates that the approach can reduce memory usage by several orders of magnitude.
Cemracs project: A composite finite volume scheme for the Euler equations with source term on unstructured meshes
Authors: Boujoudar Mohammed , Franck Emmanuel , Hoch Philippe , Lasuen Clément , Le Hénaff Yoan , Paragot Paul
Published: November 2024

In this work we focus on an adaptation of the method described in [1] in order to deal with source term in the 2D Euler equations. This method extends classical 1D solvers (such as VFFC, Roe, Rusanov) to the two-dimensional case on unstructured meshes. The resulting schemes are said to be composite as they can be written as a convex combination of a purely node-based scheme and a purely edge-based scheme. We combine this extension with the ideas developed by Alouges, Ghidaglia and Tajchman in an unpublished work [2] – focused mainly on the 1D case – and we propose two attempts at discretizing the source term of the Euler equations in order to better preserve stationary solutions. We compare these discretizations with the “usual” centered discretization on several numerical examples.
A well-balanced scheme using exact solutions to the two species Vlasov-Poisson system
Authors: Crouseilles Nicolas , Lemou Mohammed , Morel Guillaume , Navaro Pierre
Published: November 2024

In this work, we consider the numerical approximation of the two-species Vlasov-Poisson system using Eulerian methods. A family of exact non homogeneous stationary solutions are constructed using elliptic functions. Then, specific numerical schemes are proposed to compute solutions which remain close to a given stationary solution since standard schemes fail to capture such a dynamics on coarse meshes. The strategy is based on a suitable decomposition of the solution (in the spirit of δ f approaches) which can be easily combined with any classical Vlasov solvers. For unstable dynamics, a projection technique is proposed in order to dynamically change the equilibrium. Finally, numerical tests are proposed to illustrate the good behavior of the proposed strategy.
Das diabetische Makulaödem – Patientenkollektiv und Behandlungsrealität in einem deutschen Universitätsklinikum
Authors: Eder Anna Mareike , Sekundo Walter , Besgen Volker , Schulze Stephan
Published: November 2024

Hintergrund Das diabetische Makulaödem (DMÖ) ist mit einem relevanten Visusverlust assoziiert. Den aktuellen Goldstandard zur Behandlung dieser Erkrankung stellen intravitreale Injektionen mit einem VEGF-Inhibitor dar, die Zweitlinientherapie eine Behandlung mit intravitrealen Steroiden. Diese Therapie wurde in großen randomisierten Studien bereits umfangreich untersucht. In dieser Arbeit sollen die Patientinnen und Patienten sowie die Therapiemöglichkeiten in einem Real-World-Setting evaluiert werden.

Material und Methoden Es wurden Daten von 176 Augen von 114 Patienten der Augenklinik des Universitätsklinikums Marburg, die im Jahr 2018 mindestens eine intravitreale Injektion bei der Diagnose DMÖ erhalten haben, retrospektiv ausgewertet. Untersucht wurden dabei demografische Charakteristika, Vorbehandlung, durchgeführte Therapien sowie die Entwicklung des Visus und die der zentralen Netzhautdicke. Mithilfe multipler linearer Regressionsanalysen wurde der Einfluss der verschiedenen Variablen auf die abhängigen Variablen Visusänderung (logMAR), Netzhautdickenänderung (µm) sowie Injektionsanzahl untersucht. Dabei wurden ebenso die Einflüsse der Variablen untereinander berücksichtigt.

Ergebnisse Patienten waren durchschnittlich 64,45 ± 13,79 Jahre alt und überwiegend männlich (61,93%). Mit 71,59% war ein Großteil bereits bez. des DMÖs vorbehandelt. Der Ausgangsvisus lag bei durchschnittlich 0,42 logMAR ± 0,34, der Ausgangswert der zentralen Netzhautdicke bei 369,1 µm ± 118,81. Im beobachteten Zeitraum wurden insgesamt 688 intravitreale Injektionen verabreicht, pro Auge durchschnittlich 3,91 ± 2,22. Es zeigte sich eine durchschnittliche Visusverbesserung um 0,04 logMAR ± 0,18, wobei Augen mit einem schlechteren Ausgangsvisus eine stärkere Visuszunahme verzeichneten. Bezüglich des CRT-Wertes kam es zu einer durchschnittlichen Reduktion um 44,54 µm ± 133,95. Augen mit einem höheren Ausgangswert zeigten eine stärkere Reduktion. In den Regressionsanalysen konnte außerdem erstmalig gezeigt werden, dass bereits vorbehandelte Augen weiterhin vermehrt Injektionen benötigen könnten.

Fazit In dieser Arbeit konnte die Behandlungsrealität des DMÖs in einem deutschen Universitätsklinikum detailliert dargestellt werden. Es konnte aufgezeigt werden, welche Unterschiede zu RCTs existieren und was das Patientenkollektiv charakterisiert.
Spezielle Orthopädische Geriatrie (SOG) – G-BA Modellprojekt zur
Versorgung orthogeriatrischer Patienten mit elektiven orthopädischen
Eingriffen
Authors: Kappenschneider Tobias , Meyer Matthias , Grifka Joachim , Maderbacher Günther
Published: November 2024

Durch die demographische Entwicklung ist in den nächsten Jahren und Jahrzehnten
mit einer deutlichen Zunahme geriatrischer Patienten im deutschen
Gesundheitssystem zu rechnen. So wird auch die Anzahl älterer Patienten in den
Fachgebieten Unfallchirurgie und Orthopädie weiter erheblich zunehmen. Während
sich die Unfallchirurgie diesbezüglich durch zertifizierte Alterstraumazentren,
der Richtlinie zur Versorgung der hüftgelenknahen Femurfrakturen des Gemeinsamen
Bundesausschuss (G-BA) und der geriatrischen frührehabilitativen
Komplexbehandlung mittlerweile gut aufgestellt hat, existieren in der Orthopädie
mit überwiegend elektiven Eingriffen bisher noch keine adäquaten Antworten
hierauf. Doch gerade in der Primär- und Revisionsendoprothetik sowie auch bei
Wirbelsäuleneingriffen ist mit dramatisch steigenden Zahlen älterer,
multimorbider Patienten zu rechnen. Das G-BA Modellprojekt „Spezielle
Orthopädische Geriatrie (SOG)“ evaluiert auf wissenschaftlicher Grundlage
erstmals in Deutschland ein speziell auf die Elektivsituation abgestimmtes,
innovatives Versorgungskonzept in der interdisziplinären Behandlung
orthogeriatrischer Patienten bei primärem Hüft- und Kniegelenkersatz. In einer
ersten Zwischenanalyse zeigten sich bereits vielversprechende Ergebnisse. Im
Erfolgsfall könnte das Konzept für die Behandlung weiterer Erkrankungen
übernommen und als neue Komplexbehandlung für elektive chirurgische Eingriffe
etabliert werden.
Endoscopic transpapillary gallbladder drainage is associated with favorable long-term outcomes in patients with advanced liver disease
Authors: Cooper Katherine M. , Winkie Mason , Achebe Ikechukwu , Devuni Deepika , Mehta Savant
Published: November 2024

Background and study aims Endoscopic gallbladder therapy is increasingly used in high-risk surgical patients, but data in advanced liver disease are lacking.

Patients and methods We performed a single-center retrospective analysis of patients with cirrhosis undergoing endoscopic transpapillary gallbladder drainage (ET-GBD) with cystic duct stenting (n = 55). Short-term outcomes were assessed at Day 30. Long-term outcomes were assessed at 6 months and 1 and 3 years or last known follow-up. Subgroup analyses were completed by location (inpatient vs. outpatient).

Results A total of 52 patients, mean MELD-Na 16, underwent successful ET-GBD (38 inpatient, 14 outpatient). Most patients (n = 48) experienced immediate symptomatic relief. Short-term adverse event rate was 7.7% and 30-day mortality was 1.9%. At 6 months, 86.5% of patients had a favorable outcome; unfavorable outcomes included death (n = 2), recurrent cholecystitis and/or need for urgent cholecystectomy (n = 5). At the end of the study, 80% of patients experienced a favorable outcome including five patients bridged to liver transplant and 20 who had their stent in place with adequate symptom control. Of those with imaging, 65% of patients experienced resolution of cholelithiasis. Recurrent cholecystitis (P = 1.00) and stone resolution (P = 0.35) did not differ in patients with one or two cystic duct stents in place.

Conclusions Transpapillary gallbladder stenting is technically feasible and associated with high rates of clinical success in patients with decompensated liver disease. Stone resolution is common after transpapillary gallbladder stenting and may portend favorable patient outcomes.
Texture and color enhancement imaging versus white light imaging for the detection of colorectal adenomas: Systematic review and meta-analysis
Authors: Mitev Stefan , Saeed Humza , Rasheed Ch Faizan , Abdullah A , Murvakov Stefan , Sirakov Vassil , Tchernodrinski Stefan , Spassova Zoya
Published: November 2024

Texture and color enhancement imaging (TXI) is a novel optical technology designed to improve visibility during endoscopy by highlighting subtle differences in morphology and color. This systematic review and meta-analysis aimed to determine whether TXI, compared with conventional white light imaging (WLI), can improve important colonoscopy quality indicators, specifically the adenoma detection rate (ADR) and adenomas per colonoscopy (APC).

We searched PubMed, EMBASE, and the Cochrane Central for studies comparing TXI to WLI in patients undergoing colonoscopy for any indication. Risk ratios (RRs) and mean differences (MDs) were computed using a random-effects model.

We included 1541 patients from three studies, of which two were randomized controlled trials (RCTs). TXI was used in 775 patients (50.3%). Indications for colonoscopy varied, including positive fecal immunochemical test (FIT), surveillance, and diagnostic workup for abdominal symptoms. In the pooled data, TXI significantly increased both ADR (57,8% versus 43.6%; RR 1.32; 95% confidence interval [CI] 1.20-1.46; P < 0.001; I2 = 0%) and APC (MD 0.50; 95% CI 0.37-0.64; P < 0.001; I2 = 0%), compared with WLI. Furthermore, TXI was more effective at detecting nonpolypoid/flat adenomas, proximal/right-sided adenomas, and adenomas ≥ 10 mm in size. Colonoscopies with TXI had shorter withdrawal times.

Our meta-analysis demonstrates that TXI significantly improves detection of colorectal adenomas in patients undergoing colonoscopy for various indications. TXI has the potential to improve overall quality of colonoscopy and contribute to colorectal cancer prevention.
Ingestible sensor capsule with extended battery capacity allows early diagnosis of GI malignancy in comorbid patients with occult bleeding and anemia
Authors: Cahyadi Oscar , Ewald Peter , Quast Daniel , Siau Keith , Uhl Waldemar , Schmidt Wolfgang , Torres Reyes Christian
Published: November 2024

HemoPill is a commercially available ingestible electronic capsule that detects hematin and blood through photometric measurements. An examination with HemoPill requires no special preparation and can be done bedside. Its major advantage is noninvasive luminal blood detection, requiring only a small amount of blood or hematin (> 20 mL) for a positive result, making it especially suitable in multimorbid and/or geriatric patients not primarily fit for endoscopic diagnostic allowing rapid and uncomplicated bleeding detection.

Recent clinical reports showed that HemoPill is useful in stratifying patients with anemia and bleeding in the setting of an Emergency Department. The second generation with an extended battery capacity of 9 hours opens the possibility of detecting blood in the middle and lower gastrointestinal tract.

Herein we report another advantage of the extended battery capacity allowing noninvasive bleeding detection in the middle and lower gastrointestinal tract, leading to early endoscopic diagnosis of gastrointestinal malignancies with occult bleeding in comorbid patients with severe anemia.
A Portal to Highly Valuable Pyridonyl Vinyl Sulfonyl Fluorides and Aliphatic Sulfonyl Fluorides
Authors: Qin Hua-Li , Zeng Shi-Qi , Fayad Eman , Abu Ali Ola A. , Sun Bing
Published: November 2024

A novel and efficient method for selective Michael addition of 2-pyridones to ethenesulfonyl fluoride (ESF) and 1-bromoethene-1-sulfonyl fluoride (BESF) has been developed for constructing a class of pyridonyl aliphatic sulfonyl fluorides and pyridonyl vinyl sulfonyl fluorides in good to excellent yields. This practical method features easy operation, wide substrate scope, and mild reaction conditions.
Percutaneous Cystic Duct Stenting: Report of Two Cases
Authors: Paul Shouvik , Singh Anupam , Irrinki Santosh , Dahiya Divya , Gupta Pankaj
Published: November 2024

Percutaneous cholecystostomy involves the placement of a catheter in the gallbladder via image-guided puncture through either a transhepatic or a transperitoneal route. It is most commonly utilized for managing patients with moderate to severe acute cholecystitis who are otherwise unfit for immediate surgery. While the procedure has a high technical success rate, there is significant morbidity, mainly due to catheter-related issues. Endoscopic ultrasound (EUS) guided drainage offers the advantage of internal drainage, potentially alleviating catheter-related risks. However, EUS-guided gallbladder drainage requires a high degree of expertise. There are reports of percutaneous cholecystostomy being converted into internal drainage using endoscopic approaches. We report two cases of percutaneous cystic duct stenting.
Perspective on the Influence of Biopsy on the Survival of Pediatric Patients with Diffuse Brainstem Gliomas: A Literature Review
Authors: Biondi-Soares Ádria Gabrielle , Biondi-Soares Luís Gustavo , Pereira Felipe Salvagni , Kus Willian Pegoraro , Batista Ludimila Brito , Formentin Cleiton
Published: November 2024

Introduction Diffuse brainstem gliomas (DBG) represent the most common subtype of pediatric brainstem tumors, characterized by a systematically grim prognosis with a median survival rate of 10% two years post-diagnosis. Unlike other brain tumors, diffuse brainstem gliomas have traditionally relied on cranial magnetic resonance imaging (MRI) as a sufficient diagnostic tool, rendering surgical biopsies deemed unnecessary.

Objectives To conduct a literature review aiming to assess whether the performance of surgical biopsies has influenced the survival outcomes of children with diffuse brainstem gliomas.

Materials and Methods A comprehensive literature review was conducted using electronic databases PubMed, Embase, and LILACS. The search terms included “glioma” or “diffuse glioma” in conjunction with “pediatric” or “childhood,” combined with “biopsy” or “stereotactic,” and further combined with “brainstem,” “pons,” “pontine,” or “mesencephalon,” along with “survival.” The searches were limited to studies involving pediatric patients (age <18 years) published between 1980 and 2021.

Results The analysis of the presented data revealed morbidity ranging from 0% to 33.3% and mortality from 0% to 2.2%. Transfrontal access was predominantly favored by most authors, followed by transcerebellar approaches. The rate of inconclusive biopsies varied from 0% to 30%.

Conclusion Given the infiltrative nature of diffuse brainstem gliomas; surgical resection is generally deemed impractical. Radiation therapy remains the standard treatment, providing a marginal survival benefit of ∼3 months. There is currently no established chemotherapy protocol for this pathology.
How does colonial history matter for expatriate adjustment? The case of Brazilians in Portugal
Authors: Aguzzoli Roberta , Śliwa Martyna , Lengler Jorge , Brewster Chris , Quatrin Denise Rossato
Published: November 2024

The literature on expatriation typically assumes that cultural and institutional familiarity facilitates expatriate adjustment. This assumption underplays the role of the historical context, especially the influence of painful colonial pasts that often lie beneath such familiarity. In addition, seeking to capture expatriate adjustment as a single measure, such literature does not engage with the differences in the extent to which expatriates achieve cognitive, behavioral, and affective adjustment. Using a qualitative study addressing the work experiences of Brazilians living in Portugal, we argue that to fully understand expatriate adjustment, we must pay attention to the historical colonial relationship between the expatriate’s home and host country. Specifically, we discuss the importance of social representations of history for how expatriates narrate, interpret, and act in response to their experiences. Our research makes two theoretical contributions. First, we explain how historical colonial relationships affect expatriate adjustment and how this leads to adjustment only being partial. Second, we develop a nuanced understanding of expatriate adjustment by drawing attention to its three interdependent dimensions (cognitive, behavioral, and affective), showing that an expatriate may be well adjusted in one dimension but less adjusted in another. We call for organizations to engage more, and more critically, with history.
Electrical and optical properties of the magnetic semiconductor MnTe
Authors: Pereverzev Yu. V. , Povstyanyi L. V. , Zvyagin A. I.
Published: November 2024

The electrical and optical properties of the antiferromagnetic semiconductor MnTe (TN =307°K) are investigated in the temperature interval 4.2−350°K. The temperature dependence of the electrical resistivity ρ(T) is calculated allowing for carrier scattering by magnons and optical and acoustic phonons and also for “drag” effects. It is shown that the resistivity is due primarily to optical phonons. The calculated and experimental curves are in good agreement up to TN.
Subthreshold absorption in low-dimensional uniaxial antiferromagnets
Authors: Pereverzev Yu. V. , Stepanov A. A.
Published: November 2024

Two-magnon subthreshold absorption (TSA) in uniaxial quasi-two-dimensional and quasi-one-dimensional antiferromagnets is investigated theoretically. As in ferromagnets, this absorption reflects the characteristics of the magnon density of states that are due to the low dimensionality of the magnetic structure. For orientations of the external magnetic field H with respect to the anisotropy axis of the crystal H∥ z, H ┴ z and various polarizations of the radio-frequency field hω ∥ H, hω ┴ H there are four types of TSA corresponding to excitation of two magnons from the same or different branches of the spectrum. A comparison of the integral intensities of antiferromagnetic resonance and TSA in such crystals shows that they can be of the same order of magnitude.
Metastable states in solid helium-4 during the α → γ-phase transition
Authors: Efimov V. B. , Mezhov-Deglin L. P.
Published: November 2024

Experiments are described for the observation of the metastable α - and γ-phases during phase transitions in solid He4. It turned out that the supercooled γ-phase and the superheated α -phase can be observed at temperatures which differ from the equilibrium transition temperature by 0.8% to 3%. The lifetime of the metastable phases is at least longer than 100 sec. For large velocities of the α → γ-phase transition boundary (ν ≥ 1 cm/sec), visually observed cracks and fractures develop in the crystal (the maximum stress at the boundary ≤ 30 N/cm2), and for small velocities (ν ≤0.1 cm/sec), the stresses which develop in the body at the phase separation boundary are able to relax at the crystal surface.
Critical currents of thin films and their relation to inhomogeneities of superconductor parameters
Authors: Moshenskii A. A. , Fogel’ N. Ya. , Sidorenko A. S. , Glukhov A. M. , Dmitrenko I. M. , Tishchenko L. P. , Fogel’ Ya. M.
Published: November 2024

The influence of implanting helium ions on the critical current of thin indium films in a perpendicular magnetic field is investigated. The critical current in a mixed state diminishes, as a rule, with an increase in the exposure dosage in the weak magnetic field range Hcr1≪H≪Hcr2. The dependences observed experimentally of the critical current on the temperature, magnetic field, and exposure dose are described well by the Larkin-Ovchinnikov theory which takes account of the influence of spatial inhomogeneities in the mean free path l and the interelectron interaction constant g on the critical current. It follows from a comparison with theory that a vortex lattice is realized in the films investigated, where the shear modulus C66 of the vortex lattice in the film changes with a reduction in temperature because of the change in sign of the inequality between the vortex lattice parameter and the effective penetration depth. A comparison between experimental results and theory also permits making the deduction that indium films become more homogeneous because of exposure.
Spin-flipping of magnetic sublattices in ferroelectric-antiferromagnets
Authors: Chupis I. E.
Published: November 2024

It is shown that the exchange interaction between the electric and magnetic subsystems of a uniaxial ferroelectric-antiferromagnet leads to the appearance of a jump in the electrical polarization in the spin-flip field of the magnetic moments. This interaction can also cause the second-order phase transition to change into a first-order transition in strong magnetic fields. The temperature dependence of these effects is investigated.
The bound state of N bosons in a one-dimensional system with pairwise and three-body interactions
Authors: Kovalev A. S. , Kosevich A. M.
Published: November 2024

A one-dimensional system of a finite number of bosons with a δ-like interaction potential is treated. A three-body boson repulsion is taken into account, along with the pairwise attraction. The bound state of N bosons is found in the self-consistent-field approximation. In such a system there is no collapse of the Bose gas, and the ground state in the thermodynamic limit is the bound state of N particles with a practically constant density. Such a state can be considered as a condensate droplet in the coordinate space.
Change of the dynamic characteristics of layered crystals with intercalated organic molecules
Authors: Verkin B. I. , Sukharevskii B. Ya. , Gurevich A. M. , Alapina A. V. , Dushechkin Yu. A.
Published: November 2024

It was demonstrated experimentally that Pbl2 in the 2−20 °K temperature region has a temperature dependence of heat capacity characteristic for layered structures. The change of Cp(T) of Pbl2 as a result of intercalated piperidine is due to intensification of the interaction of the layers and, possibly, the contribution of electrons to the heat capacity. Estimates of the electronic heat capacity obtained within the framework of a two-dimensional model of free electrons are given.
Stability of supercooled liquid argon in a molecular-mechanical model
Authors: Baidakov V. G. , Galashev A. E. , Skripov V. P.
Published: November 2024

The stability of supercooled liquid argon is investigated using a model involving 108 interacting particles. In the course of integrating the classical equations of motion, values are obtained for the thermodynamic properties, radial distribution function, and static and dynamic structure factors. It is shown that, in this model, the supercooled liquid shows no tendency toward thermodynamic instability at supersaturation. The problem of short-wave static and dynamic stability of the liquid in the metastable (supercooled) region is discussed.
Perfecting refrigerator freezers through magnetic resonance velocimetry
Authors: Lange Katherine De
Published: November 2024

Using magnetic resonance velocimetry facilitates precise structural modifications based on flow characteristics and turbulent kinetic energy
Self-cooling in reverse biased p-InAsSbP/n-InAs0.9Sb0.1 heterostructures
Authors: Karandashev S. A. , Lavrov A. A. , Lukhmyrina T. S. , Matveev B. A. , Remennyi M. A.
Published: November 2024

2D thermal radiation distribution together with I–V and L–I characteristics has been measured and analyzed in forward and reverse biased p–n heterostructures based on InAs0.9Sb0.1 and grown onto n-InAs substrates. The measurements revealed a sufficient difference in the temperature distribution onto the sample surface at forward and reverse bias, which is explained by an impact of heat pump operation initiated by an electron–phonon interaction at the p–n junction and diode contacts at U < 0.
The infrared thermography system on the MAST-U tokamak
Authors: Stobbs J. M. , Tookey A. , Thornton A. J. , Farley T. ,   MAST-U Team
Published: November 2024

Power loading from plasma in the scrape-off layer limits the lifetime of plasma-facing components in tokamak-based power plants. The Mega Ampere Spherical Tokamak Upgrade [W. Morris et al., IEEE Trans. Plasma Sci. 46(5), 1217–1226 (2018)] (MAST-U) features four divertor strike points (SP) owing to its up-down symmetry. This paper introduces the five-camera infrared thermography system, covering all four SPs and their mode of operation on MAST-U. The system employs both medium and long wavelength cameras, offering high frame rates up to 4 kHz and spatial resolutions of down to 3 mm. Postprocessing involves artifact elimination and heat flux calculation using in-house analysis software that incorporates the inverse heat transfer code, THEODOR (THermal Energy Onto DivertOR).
Continuous wave GaSb-based interband cascade lasers with hybrid cladding layers operated at room temperature and above
Authors: Shen Yixuan , Yang Rui Q. , Mishima Tetsuya D. , Santos Michael B. , Wang Xiaojun
Published: November 2024

We report the preliminary demonstration of continuous wave (cw) GaSb-based interband cascade lasers (ICLs) with hybrid cladding layers at high temperatures up to 80 °C near a wavelength of 3.72 μm. These ICLs have narrow-ridge widths of 7–11 μm with improved thermal dissipation compared to broad-area devices. They delivered a cw output power of more than 30 mW/facet at 20 °C and had a cw threshold current density of 270 A/cm2 with a voltage efficiency of 78% at 300 K. The obtained voltage efficiency of 78% is the highest ever reported among cw GaSb-based ICLs at room temperature, indicating an advantage of efficient carrier transport in the ICL with the hybrid cladding layers. The dependence of device performance on the narrow-ridge width and cavity length was investigated. The results suggested ways to further improve future devices.
Metal-halide perovskites under pressure: Effect of anisotropic deformation on optoelectronic properties
Authors: Zhang Siyu , Liu Mengyu , Su Jie , Lin Zhenhua , Yuan Haidong , Guo Lixin , Hao Yue , Chang Jingjing
Published: November 2024

Significant differences from typical semiconductors are observed in organic lead halide perovskites, which arise from the hybrid nature and soft lattice that make them sensitive to external driving forces, such as temperature and pressure. Here, the study employs first-principles calculations to investigate the structural, electrical, optical, and mechanical properties of pressure-induced perovskite (FAPbI3). Cubic FAPbI3 (Pm3m) undergoes a series of phase transitions as pressure increases from 0 to 9 GPa: transitioning to a tetragonal phase at ∼2 GPa, an orthorhombic phase around 5 GPa, and eventually to a monoclinic phase near 8 GPa, accompanied by reductions in lattice constant, bond length, and octahedral angle. The anisotropic structural deformation adjusts the bandgap from 1.43 eV at 0 GPa to 1.10 eV at 5 GPa, resulting in a redshift, suggesting that photoelectric conversion efficiency could be enhanced under pressures less than 5 GPa. In addition, increased pressure enhances the ductility of FAPbI3, evident from the anisotropy ratio increasing from 1.2 at 0 GPa to 2.0 at 9 GPa. The significant tunability of FAPbI3 under modest pressure ranges, combined with its increased anisotropy and ductility, opens new paradigms for its optoelectronic applications in extreme environments.
Solving the puzzle of higher photoluminescence yield at the edges of MoS2 monolayers grown by chemical vapor deposition
Authors: Mujeeb Faiha , Mahamiya Vikram , Singh Arushi , Kothari Mansi , Chowdhury Arindam , Shukla Alok , Dhar Subhabrata
Published: November 2024

Higher photoluminescence yield from the boundaries as compared to the interiors in monolayer (1L) islands of transition metal dichalcogenides grown by chemical vapor deposition (CVD) has been frequently documented in the literature. However, the detailed understanding of this phenomenon is still lacking. Here, we investigate the effect observed in CVD grown 1L-MoS2 islands on c-sapphire substrates. The study reveals a blue shift of the A-excitonic feature from the interiors to the edges of the monolayers, suggesting the release of the tensile strain, which is resulting in the interiors due to lattice and/or thermal expansion coefficient mismatch between the layer and the substrate, toward the boundaries. The degree of valley polarization is also found to increase at the edges. However, when the as-grown monolayers are transferred on a SiO2 surface, the intensity, position, and valley polarization of the A-excitonic peak do not show any inhomogeneity over the surface. The study attributes the decrease in PL intensity and the valley polarization in the interiors as compared to the edges of these as-grown islands to the reduction of the energy gap between the Γ- and K-valley valence band maxima with the increase in the tensile strain in the layer. First principles density functional theory based calculations for the geometry optimization are performed on a 1L-MoS2 flake residing on a (0001) sapphire surface, which indeed shows the relaxation of tensile strain toward the edges.
Generation of quasi-monoenergetic proton beams from near-critical density plasmas irradiated by picosecond laser pulses
Authors: Wei Yuqing , Wang Weiquan , Zou Debin , Liu Ke , Zhang Guobo , Zhao Na , Yu Tongpu , Shao Fuqiu
Published: November 2024

Laser-driven high-quality ion beams hold immense potential for applications in diverse fields such as tumor therapy, fast ignition, and so on. However, current experimental ion beams are often constrained by either a large energy spread or relatively low energy. In this paper, we proposed a novel scheme for generating quasi-monoenergetic proton beams by irradiating near-critical-density plasmas, which have a density gradient with a picosecond laser pulse. This approach leverages two key aspects: first, the sustained interaction between the laser pulse and the plasma enhances the duration of magnetic vortex acceleration, thereby promoting extended ion acceleration. Second, the utilization of a multi-species target facilitates the formation of a dual-peaked electric field, which leads to the accumulation of protons in the negative gradient of the accelerating phase, resulting in a quasi-monoenergetic proton beam. The two-dimensional particle-in-cell simulation reveals that by employing a laser intensity of 1.37 × 1020 W/cm2 with a pulse duration of 0.5 ps, we can achieve a carbon ion beam with an energy of 50 MeV/u, and a quasi-monoenergetic proton beam exhibiting a cutoff energy of 160 MeV/u, a peak energy of 75 MeV/u, an energy spread of 3.1 %, and an angle divergence of ∼ 3.2°. Furthermore, the quasi-monoenergetic property is corroborated in three-dimensional simulation results, underscoring the robustness and effectiveness of our proposed scheme.
Scalable approach for growing hexagonal boron nitride on silicon and its role in III-nitride van der Waals epitaxy
Authors: Rather Muzafar Ahmad , Hsu Shao-Hsiang , Lin Chih-Chieh , Tien Yen-Huang , Wu Chien-Ting , Yu Tung-Yuan , Lin Kun-Lin , Lai Kun-Yu , Chyi Jen-Inn
Published: November 2024

Hexagonal boron nitride (h-BN) stands out among 2D materials for its insulating properties, making it promising for the integration of 2D and 3D materials. However, achieving wafer-scale growth on silicon substrates remains a significant challenge. In this study, growth strategies for depositing h-BN on Si substrates are explored utilizing the wafer scalable metalorganic chemical vapor deposition. Our investigations reveal that employing a pulsed flow mode scheme is preferable over the conventional continuous flow mode scheme in growing h-BN thin films on 150 mm Si substrates. The as-grown h-BN film on Si exhibits uniform coverage with h-BN[0001]//Si[111]. With the successful wafer-scale growth of h-BN on Si, its role in aiding the van der Waals epitaxy of III-nitrides on Si substrates and subsequent epitaxial lift-off (ELO) of III-nitrides is further exemplified. An optimized h-BN thickness for the ELO process is also determined.
Nonlinear optical properties of some nanosized ammonium dihydrogen phosphate crystals incorporated in aluminum oxide nanopores
Authors: Guichaoua D. , Alnusirat W. , Adamiv V. , Andrushchak N. , Teslyuk I. , Shulha D. , Andrushchak A. , Gnilitskyi I. , Sahraoui B.
Published: November 2024

This study explores the nonlinear optical properties of aluminum oxide (Al2O3) matrices embedded in ammonium dihydrogen phosphate (ADP) nanocrystals using third-harmonic generation (THG) techniques. The successful integration of ADP crystallites within the nanopores of the Al2O3 matrix was confirmed using x-ray structural analysis and electron microscopy. The optical absorption characteristics were examined over a wide wavelength range, revealing that the reflection and transmission spectra were notably affected by pore size and surface scattering effects. THG measurements conducted with a high-intensity infrared laser demonstrated a pronounced third-order nonlinear response, whereas second-harmonic generation was not observed. The absence of SHG can be attributed to phase mismatch and inherent material properties, including centrosymmetry and surface roughness. The comparative and Reintjes models were used to calculate the third-order nonlinear optical susceptibilities. Among these, the Reintjes model provided the most accurate fit for the experimental data. This research underscores the considerable influence of nanopore size on THG efficiency, highlighting the importance of light scattering and phase-matching conditions. These findings contribute to a growing body of knowledge regarding nonlinear optical phenomena in nanocomposite materials and offer valuable insights for future applications in photonic devices. This comprehensive analysis highlights the potential of Al2O3 matrices with embedded ADP nanocrystals to advance the field of nonlinear optics in nanocomposite materials and offers insights for prospective applications in photonic devices.
Research on the impact of grinding speed on surface/subsurface damage in monocrystalline silicon by workpiece rotational grinding
Authors: Zhang Xiaoqiu , Ma Jiaheng , Liu Ziyuan , Ma Fujian , Wang Ziguang , Zhang Shengfang
Published: November 2024

To investigate the effect of grinding speed on the surface/subsurface damage of monocrystalline silicon grinding, experiments of grinding monocrystalline silicon wafers with different grinding speeds under the condition of equal abrasive cutting depth were designed based on the workpiece rotation method. The surface morphology, roughness, surface cracks, deformations, and residual stresses after machining were analyzed through comparative experiments, and the reasons for the effect of different machining speeds on the number of cracks and depth of subsurface damage were analyzed in combination with molecular dynamics simulation models. The results indicated that with the increase in grinding speed, the surface quality gradually becomes better. Furthermore, when the grinding speed is 2399 rpm, the surface roughness Ra value formed by Nos. 600 and 5000 grinding wheels is reduced by 22.5% and 31.2%, respectively, compared with 239 rpm. Besides, when grinding with the No. 600 grinding wheel, the higher the grinding speed, the fewer the number of subsurface cracks and the smaller the crack depth. Besides, when the grinding speed is 2399 rpm, the number of cracks is reduced by about 50%, and the depth of cracks is reduced by about 25% compared with 239 rpm. Moreover, when grinding with the No. 5000 grinding wheel, the deformation and residual stress of the silicon wafer gradually decrease with the increase in grinding speed. The deformation formed at a grinding speed of 2399 rpm is about 44% lower than that at 239 rpm. With the increase in grinding speed, the number of cracks, deformation, and residual stress of silicon wafer are reduced. Moreover, the increase in grinding speed will help reduce the damage degree of the crystal structure and the thickness of the damage layer of the silicon wafer, thus improving the quality of the grinding surface.
High-quality temperature-complementary bulk acoustic wave resonators fabricated with strippable single-crystalline AlN films grown on sapphire
Authors: Luo Tianyou , Zhang Yinuo , Chen Zhipeng , Xu Kaibin , Ouyang Peidong , Hu Han , Li Chenyang , Zhu Yuhan , Yi Xinyan , Li Guoqiang
Published: November 2024

To satisfy the strict demands of 5G radio frequency communication, we propose high-quality, flexible temperature-compensated single-crystalline AlN film bulk acoustic wave resonators (TC-SABARs) based on a 6-inch sapphire substrate. An AlGaN sacrificial layer and a 600-nm-thick single-crystalline AlN epitaxial layer are deposited on a sapphire substrate by metal organic chemical vapor deposition (MOCVD). Two types of TC-SABARs are fabricated and their performances are compared with published results. The results indicate that one of the TC-SABARs has a maximum Bode Q of 3406, an effective coefficient (Keff2) of 6.21%, and a temperature coefficient of frequency (TCF) of −9.5 ppm/°C. The other TC-SABAR exhibits a maximum Bode Q of 3022, a Keff2 of 5.99%, and a TCF of +0.7 ppm/°C. This performance can be attributed to the high-quality single-crystalline AlN film and the temperature-compensation structure with nonmetallic flip-chip bonding film transfer process and a thick SiO2 layer.
Existence of a maximum flow rate in electro-osmotic systems
Authors: Varghese Sleeba , Todd B. D. , Hansen J. S.
Published: November 2024

In this work, we investigate the effect of the hydrodynamic wall–fluid friction in electro-osmotic flows. First, we present the solution to the electro-hydrodynamic equation for the electro-osmotic velocity profile, which is derived for an ionic system composed of cations immersed in uncharged solvent particles. The system (solution and walls) is kept electrically neutral using negatively charged walls and will here be referred to as a “counterion-only” system. The theory predicts the existence of a counterion concentration that results in maximum electro-osmotic flow rate, but only if the wall–fluid friction, or equivalently the slip length, is correlated with the system electrostatic screening length. Through equilibrium molecular dynamics simulations, we precisely determine the hydrodynamic slip from the wall–fluid friction, and then, this is used as input to the theoretical predictions. Comparison between the theory and independent non-equilibrium molecular dynamics simulation data confirms the existence of the maximum. In addition, we find that standard hydrodynamic theory quantitatively agrees with the simulation results for charged nanoscale systems for sufficiently small charge densities and ion charges, if the correct slip boundaries are applied.
The effects of in-nozzle phase transition on injection characteristics of near- and supercritical kerosene jets
Authors: Liu Guigui , Lin Yuzhen , An Qiang , Xue Xin , Hui Xin
Published: November 2024

The escalating requirements for thermal management in advanced high-performance aviation engines necessitate the injection of aviation fuels under near- and supercritical conditions. The jet morphology both exterior and interior to the nozzle of aviation kerosene jets, injected from near-critical and supercritical states into a quasi-quiescent, near-atmospheric environment, was experimentally investigated, focusing on the effects of in-nozzle phase transitions. The in-nozzle flow behavior was characterized using shadowgraph imaging and pressure profile measurements, while downstream jet behavior was captured using both shadowgraph imaging and planar Mie scattering techniques. It is found that without observable in-nozzle phase transitions (OIPTs), the near-nozzle jet structure exhibits low sensitivity to injection temperature. However, under OIPT conditions, a reduction in injection temperature precipitates notable increases in jet expansion angle, jet diameter, and Mach disk diameter. Additionally, it initially provokes a downstream displacement of the Mach disk, subsequently reversing its direction upstream. Analysis using the surrogate fuel thermodynamic phase diagram indicates that without OIPT, jets injected from the supercritical and vapor states disintegrate similarly due to stages of isentropic expansion, compression, and isobaric mixing, leading to fuel condensation. Under OIPT conditions, crossing the Widom line or saturation line leads to an increase in the specific heat ratio of the fuel along the injection path and changes the near-nozzle shock structure from barrel-shaped to bowl-shaped, potentially triggering a compression shock wave in the ambient air. These findings are useful for the design and modification of supercritical fuel nozzles, fuel supply systems, and combustion chambers.
Slippery liquid-infused porous surfaces for high-performance moisture-responsive actuators
Authors: Chen Zhao-Di , Wang Qiang , Zhou Hao , Li Xi-Lin , Zhang Tian-Tai , Han Dong-Dong , Zhang Yong-Lai
Published: November 2024

Smart actuators convert environmental changes into mechanical energy. However, the actuation performance and robustness of smart actuators are limited by the weak interlaminar force and poor adhesion between layers. Herein, we report moisture-responsive actuators integrated with slippery liquid-infused porous surfaces (SLIPSs). The difference in adsorption capacity of water molecules further increases because the SLIPS layer is isolated from air by the lubricating oil film. Compared with the initial (graphene oxide/candle soot, GO/CS) bilayer film, the integrated SLIPS layer improved the bending performance by 12.6% and shortened the response–recovery time by one-third. Moreover, the GO/SLIPS actuator exhibited excellent long-term stability over 10 000 cycles due to the lubricating oil's capillary fluidity. In addition, a moisture-controlled water-transport device based on a GO/SLIPS film was demonstrated.