bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasticité structurelle et mécanique du pore nucléaire
Authors: Montel Fabien
Published: September 2023

Le pore nucléaire, qui peut être vu comme la porte (d’entrée et de sortie) du noyau cellulaire, joue un rôle central dans de nombreux processus, dont la régulation génique. C’est une structure complexe et dynamique. Il est composé de plus de trente protéines présentes en de multiples copies. C’est sur lui que repose le transport sélectif et orienté des ARN et des protéines. Des études récentes montrent qu’il est susceptible d’adapter sa structure globale à l’état de la cellule. La plasticité structurelle et mécanique du pore nucléaire apparaît ainsi importante pour son fonctionnement, mais aussi dans le développement de maladies comme le cancer ou les infections virales.
Der Einsatz des DFree-Ultraschallsensors für ein ausgewogenes Blasenmanagement
Authors: Schönburg Sandra Helen , Hofstetter Sebastian , Buhtz Christian , Paulicke Denny , Stoevesandt Dietrich , Jahn Patrick , Schwarz Karsten , Gakis Georgios
Published: September 2023

Hintergrund Blasenfunktionsstörungen, gleich welcher Genese, haben erhebliche psychosoziale Auswirkungen. Je nach bestehender Störung und Funktionalität sind Verhaltenstherapie und Hilfsmittel therapeutisches Mittel der ersten Wahl. Es folgen Medikationen, Interventionen und Operationen.

Ziel Der DFree-Ultraschallsensor ermöglicht die sonografische Messung des Harnblasenfüllstands und koppelt diesen per App-Anwendung an den Sensorträger zurück. Primäres Ziel der Studie war der Einfluss des DFree auf die Lebensqualität der Patienten. Sekundäre Endpunkte waren Nützlichkeit und Benutzerfreundlichkeit des DFree sowie der selbstberichtete Grad an Autonomie.

Methoden In der vorliegenden Pilotstudie wurden 18 urologische Patient*innen mit verschiedenen Blasenfunktionsstörungen über einen Zeitraum von 3 Monaten für mindestens 12 Stunden täglich mit dem DFree-Ultraschallsensor ausgestattet. Die Erhebung der Kenngrößen erfolgte zum Zeitpunkt T1 (vor Studienbeginn) und T2 (nach Studienende) anhand des Kings Health Questionnaire (KHQ) und der deutschen Version des Client Satisfaction Questionnaire (ZUF-8) (quantitative Daten) sowie eines strukturierten Interviews (qualitative Daten).

Ergebnisse Eine Verbesserung der Blasenfunktionsstörung anhand des KHQ konnte statistisch nicht bestätigt werden. Der Durchschnittswert anhand des ZUF-8 zeigte jedoch Zufriedenheit mit dem DFree. In den Interviews nach Studienende gaben die Teilnehmer ein positives Feedback mit konkreten Vorschlägen zur Verbesserung der Benutzerfreundlichkeit. Die Anwendung wurde als hilfreich und einfach zu bedienen beschrieben.

Schlussfolgerung Der DFree-Ultraschallsensor stellt ein neues technisches Hilfsmittel in der Behandlung der Blasenfunktionsstörung dar. Eine Verbesserung technischer Details könnte die Benutzerfreundlichkeit sowie die Nützlichkeit des Ultraschallsensors erhöhen.
Evaluation and Perception of an Edpuzzle Class Compared with a Traditional Class among Oral Radiology Undergraduate Students
Authors: Zain-Alabdeen Ebtihal Habeeb
Published: September 2023

Objectives Dental students are to an increasing extent presented with new digital learning technologies, especially online delivery of class content. Edpuzzle is a web-based eLearning application that allows educators to select subject-related videos and customize them by editing, cropping, voice-over recording, and adding questions directly to the video stream. Under the teacher's guidance, students log into Edpuzzle using their iPads, take the class, and answer questions. The aim of this study was to compare an Edpuzzle class with a traditional class for undergraduate oral radiology students in order to evaluate the educational effectiveness of each teaching method.

Materials and Methods The study sample comprised 20 fourth-year dental students who agreed to participate in the study. A traditional class developed a differential diagnosis topic with pre- and post-knowledge tests. A second differential diagnosis topic was developed for an Edpuzzle class, also with a pre- and post-knowledge test. After the two classes were given, a Google Forms feedback questionnaire was sent to the students to evaluate their perceptions and preferences regarding the two classes. The educational effectiveness of each class type was evaluated by comparing means and analyzing the feedback questionnaires.

Statistical Analysis The Wilcoxon signed-rank test was used to examine pre- and post-knowledge for each class, and Welch's t-test was used to test for differences in means of post-knowledge of both classes.

Results Students in both classes obtained significantly better scores in the posttest than they did in the pretest (p = 0.0001). However, the differences in means of post-knowledge of both classes showed no significant differences (p = 0.0975). The feedback questionnaire showed higher percentages of positive attitude toward Edpuzzle class.

Conclusion As a first-time experience, the Edpuzzle class interested most of the students. Workshops for the staff are needed to become expert in these technologies and to overcome any obstacles in implementing them for undergraduate dental students.
Enteric Access: IR Perspective
Authors: Lim Marc Michael Del Rosario
Published: September 2023

Gastrostomy tube placement may be needed for nutritional support, as in the setting of neurogenic dysphagia or head and neck malignancy, or for gastric decompression, as in the setting of malignant small bowel obstruction. Additionally, gastrojejunostomy or direct jejunostomy tubes may be needed in the setting of gastric outlet obstruction among other indications. Surgical, endoscopic, and percutaneous approaches are all well-described with generally similar outcomes. In this article, the standard radiologic percutaneous gastrostomy technique is reviewed including both the “push” and “pull” methods. Then, the special indications and techniques of advanced percutaneous enteral access such as percutaneous transesophageal gastrostomy and direct jejunostomy are discussed with examples shown.
What is the Sleep Pattern of Infants and Toddlers in the Iranian Population? An Epidemiological Study
Authors: Mazandarani Amir Ali , Zare Bahramabadi Mahdi
Published: September 2023

Objective To identify sleep patterns and sleep behaviors in a group of infants and toddlers (0 to 36 months) in Iran.

Methods Parents and caregivers of 602 infants and toddlers in Iran completed a Persian translation of the Brief Infant Sleep Questionnaire. To assess the differences among the age groups, non-parametric statistical approaches such as the Kruskal-Wallis and chi-square tests were employed.

Results The infants and toddlers went to bed relatively late (22:30), and the median night awakening was 2 times (20 min). They most likely slept in the same room with their parents (55.5%), and commonly in the same bed (18.9%). They slept a median of 11.50 hours per day. A significant percentage of the parents felt that their child had moderate or severe sleep problems (22.4%). These children's sleep patterns had significant developmental changes, including decreased daytime sleep, reduced overall sleep, and increased sleep consolidation (reduced number and duration of night awakenings and increased overall sleep duration). The parents commonly used holding-and-rocking and bottle/breastfeeding to initiate infants' sleep and bottle/breastfeeding to resume their infants' sleep.

Discussion These findings provide reference data for professionals to assess sleep in children under 3 years of age and also supply knowledge about common parenting practices related to a child's sleep. Cross-cultural comparisons using the findings can offer new insights into the practices and behaviors of parents concerning infant and toddler sleep.
The Cervical Fat Tissue Volume is a Predictor for Moderate to Severe OSA
Authors: Ernst Glenda , Dalzotto Pablo , Saban Melina , Ferraro Fernando M. , Salvado Alejandro , Borsini Eduardo Enrique
Published: September 2023

Objective Obstructive sleep apnea (OSA) is a disorder characterized by recurrent pharyngeal obstruction during sleep, in which upper airway anatomy plays a key role in its pathogenesis. The aim of this study was to describe whether the quantification of cervical fat tissue volume (CFTV) obtained by Computed Tomography (CT)cephalometry is related to the severity of OSA.

Methods Retrospective study between 2018 and 2020 in those patients > 18 years old, with diagnosis of OSA who performed a volumetric cephalometric imaging. Three-dimensional reconstruction of the images was performed and CFTV was measured.

Results 91 patients were included in this study of which: without OSA (n: 7), mild (n: 19), moderate (n: 39) and severe OSA (n: 26). We observed a progressive increase of CFTV related to OSA severity has been observed (without OSA: 58.9 ml (47.9-87.5), mild: 59.1ml (48.4-78.3), moderate: 71 ml (42.6-127.1) and severe OSA 103.6 ml (81-153); p < 0.01); nevertheless, no differences were found in the airway volume and neck area. It was showed a significant correlation between CFTV and OSA indicators: AHI, ODI and T90 (Sp r: 0.48; 0.38 and 0.36; p < 0.01 respectively). CFTV cut-off value to discriminate AHI >15 ev/h with best sensitivity-specificity relationship was 64.1 ml with an area under the curve of 0.6 ± 0.06. Multivariate analysis showed that CFTV is a predictor for moderate to severe OSA (OR:3.05, IC95%: 1.14-8.17).

Conclusion Cervical fat quantification by CT cephalometry correlates with OSA severity in adults. Fat volume > 64.1 ml increased more than three times the risk of OSA moderate to severe.
Advanced Treatment of Hemodynamically Unstable Acute Pulmonary Embolism and Clinical Follow-up
Authors: Fulton Brian , Bashir Riyaz , Weinberg Mitchell D. , Lakhter Vladimir , Rali Parth , Pugliese Steve , Giri Jay , Kobayashi Taisei
Published: September 2023

High-risk acute pulmonary embolism (PE), defined as acute PE associated with hemodynamic instability, remains a significant contributor to cardiovascular morbidity and mortality in the United States and worldwide. Historically, anticoagulant therapy in addition to systemic thrombolysis has been the mainstays of medical therapy for the majority of patients with high-risk PE. In efforts to reduce the morbidity and mortality, a wide array of interventional and surgical therapies has been developed and employed in the management of these patients. However, the most recent guidelines for the management of PE have reserved the use of these advanced therapies in scenarios where thrombolytic therapy plus anticoagulation are unsuccessful. This is due largely to the lack of prospective, randomized studies in this population. Stemming from this, the approach to treatment of these patients varies widely depending on institutional experience and resources. Furthermore, morbidity and mortality remain unacceptably high in this population, with estimated 30-day mortality of at least 30%. As such, development of a standardized approach to treatment of these patients is paramount to improving outcomes. Early and accurate risk stratification in conjunction with a multidisciplinary team approach in the form of a PE response team is crucial. With the advent of novel therapies for the treatment of acute PE, in addition to the growing availability of and familiarity with mechanical circulatory support systems, such a standardized approach may now be within reach.
Effect of a Hedonic Stimulus on the Sleep Architecture of Male Wistar Rats
Authors: Peña-Escudero Carolina , Priego-Fernández Sergio , Caba Mario , Rodríguez-Alba Juan Carlos , Corona-Morales Aleph Alejandro , García-García Fabio
Published: September 2023

Objective Nocturnal animals forage and eat during the night and sleep during the day. When food is available only for a short period during the day, animals develop a catabolic state and exhibit locomotor behavior before accessing food, termed food anticipatory activity. Consequently, there is a disruption in the sleep pattern. The present study aimed to explore how anticipatory arousal emerges under circadian exposure to a palatable meal (PM) and disrupts sleep architecture.

Materials and Methods Adult male Wistar rats were implanted with electrodes for continuous sleep recording and housed under a light/dark 12/12-hour cycle with free access to food and water. After basal recordings, the rats had access to a PM during the light period for eight days.

Results The anticipatory arousal started on the third day. On the eighth day, we found an increase in wake time and a decrease in the non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) times 45 minutes before the PM compared with the basal recordings. The REMS transitions (events from NREMS to REMS) showed a significant reduction during the light period of the eighth day of PM. In contrast, the number of NREMS transitions (events from wakefulness to NREMS) remained unchanged.

Conclusion The results suggest that palatable food induces a motivational timing that leads the rat to wake by altering the sleep quota.
Positive Pressure Ventilation Treatment Based on Daytime and Night-time Titration in Patients with Obesity Hypoventilation Syndrome: A Randomized Controlled Trial
Authors: Amra Babak , Ghasemi Marzieh , Soltaninejad Forogh , Salmasi Mehrzad
Published: September 2023

Objectives The aim of the present study was to investigate the improvements of gas exchange and excessive daytime sleepiness in patients with obesity hypoventilation syndrome (OHS) in daytime and night-time split polysomnography (DSPSG and NSPSG).

Materials and Methods In the present randomized controlled trial, patients with OHS were enrolled in two DSPSG (51 patients) and NSPSG (50 patients) groups in the Bamdad respiratory and sleep research center in Isfahan, Iran. In both groups, the diagnostic polysomnography (PSG) and titration were conducted in one session according to the guidelines of NSPSG. SpO2, PaCO2, and the Epworth Sleepiness Scale (ESS), were measured initially and 12 weeks after treatment. Furthermore, the PSG parameters and the type of treatments for the two groups were recorded and analyzed.

Results A total of 101 OHS patients (age: 62.02 ± 12.4 year old; 61 females [60.4%]) were evaluated. There were no significant differences regarding BMI, gender, and AHI between groups (p > 0.05). Primary SpO2, PaCO2, and ESS were not significantly different between the two groups. After 12 weeks of treatment by continuous positive airway pressure (CPAP) or bi-level positive airway pressure (BiPAP), there were significant improvement of SpO2, PaCO2, and ESS score (p < 0.001). The amount of change of these variables was not different between groups. Among all variables, only the lower SpO2 and higher PaCO2 were associated with response to BiPAP.

Discussion There were no significant differences in the number of changes of SpO2, PaCO2, and ESS by treatment in the DSPSG and NSPSG groups. Therefore, DSPSG may be considered as a valuable alternative method for the diagnosis and titration in OHS patients.

Clinical Trials IRCT20170512033930N2
Austerity and its alternatives in the European parliament: from the Eurozone crisis to the COVID-19 crisis
Authors: Elomäki Anna
Published: September 2023

This article examines the role of the European parliament (EP) in providing ideational alternatives to austerity in the context of the Eurozone crisis and the COVID-19 crisis. Despite the EP’s limited formal role in EU economic governance, it is a key site for democratic debate and contestation. Analyzing EP debates about austerity allows us to understand the possibilities and limitations for ideational change at the EU level from the perspective of supranational party politics. Through a longitudinal analysis (2012–2021) of EP resolutions on the European Commission’s Annual Growth Surveys, the article asks how ideational battles around austerity have unfolded between the EP’s political groups and what factors have shaped the EP’s positions. Theoretically, the article draws on the literature on ideational political economy and discoursive institutionalism. The article argues that instead of providing alternatives, the EP and its Committee on Economic and Monetary Affairs have contributed to the ideational hold of austerity due to the weakness of the alternatives of the center-left and their compatibility with austerity. Party-political and institutional factors, such as broad left/right compromises and a strict division of labor between the EP’s committees, further constrain ideational change.
Flexoelectricity-stabilized ferroelectric phase with enhanced reliability in ultrathin La:HfO2 films
Authors: Jiao Peijie , Cheng Hao , Li Jiayi , Chen Hongying , Liu Zhiyu , Xi Zhongnan , Ding Wenjuan , Ma Xingyue , Wang Jian , Zheng Ningchong , Nie Yuefeng , Deng Yu , Bellaiche Laurent , Yang Yurong , Wu Di
Published: September 2023

Doped HfO2 thin films exhibit robust ferroelectric properties even for nanometric thicknesses, are compatible with current Si technology, and thus have great potential for the revival of integrated ferroelectrics. Phase control and reliability are core issues for their applications. Here, we show that, in (111)-oriented 5%La:HfO2 (HLO) epitaxial thin films deposited on (La0.3Sr0.7)(Al0.65Ta0.35)O3 substrates, the flexoelectric effect, arising from the strain gradient along the film's normal, induces a rhombohedral distortion in the otherwise Pca21 orthorhombic structure. Density functional calculations reveal that the distorted structure is indeed more stable than the pure Pca21 structure, when applying an electric field mimicking the flexoelectric field. This rhombohedral distortion greatly improves the fatigue endurance of HLO thin films by further stabilizing the metastable ferroelectric phase against the transition to the thermodynamically stable non-polar monoclinic phase during repetitive cycling. Our results demonstrate that the flexoelectric effect, though negligibly weak in bulk, is crucial to optimize the structure and properties of doped HfO2 thin films with nanometric thicknesses for integrated ferroelectric applications.
Linear magnetoelectric coupling and type-II multiferroic order in NiMn2O4
Authors: Chatterjee A. , Kumar A. , Manna P. K. , Bedanta S. , Sarma A. , Majumdar S. , Yusuf S. M. , Giri S.
Published: September 2023

We report an unexplored type-II multiferroic order in NiMn2O4, exhibiting strong linear magnetoelectric coupling above liquid-nitrogen (LN) temperature. The compound becomes ferroelectric at ∼100 K, coinciding with ferrimagnetic ordering, with a polarization value of ∼535 μC/m2 for a poling field of 5 kV/cm. At LN temperature, the polarization value increases linearly (∼21%) with a magnetic field up to 30 kOe. Rietveld refinement of neutron diffraction patterns reveals a ferrimagnetic model with antiparallel moments at tetrahedral and octahedral sites, as well as a canting of octahedral moment persisting up to ∼100 K. Low-temperature synchrotron diffraction confirms a step-like oxygen displacement during multiferroic ordering, suggesting that the Dzyaloshinskii–Moriya interaction polarizes the intervening oxygen atoms through magnetostriction, providing a microscopic mechanism for spontaneous electric polarization in this linear magnetoelectric multiferroic compound.
A drum-like piezoelectric rotational energy harvester via magnetic beating
Authors: Kan Junwu , Wu Yaqi , Gu Yiqun , Wang Shuyun , Meng Fanxu , Zhang Zhonghua
Published: September 2023

In this Letter, an indirectly excited approach of introducing an air-filled separation chamber is proposed to develop a drum-like piezoelectric rotational energy harvester (DL-PREH) via magnetic beating. The harvester delivers the external excitation to the piezoelectric transducer via the intermediate air chamber, and the electric output of transducer is induced by the air pressure inside the chamber. Thus, a high reliability can be guaranteed for the harvester under an unexpected excessive impact due to the air-filled separation zone. Moreover, the harvester can easily implement a resonant frequency tuning by altering the drum height to improve the rotation speed adaptability. Its potential applications as a sustainable power source to charge different capacitors and power commercial light-emitting diodes (LEDs) are demonstrated experimentally. The fabricated DL-PREH device can achieve a maximum output power of 10.63 mW with a drum height of 6 mm at the matching resistance of 24 kΩ. Also, it can light up at least 100 blue commercial LEDs in parallel. The designed harvester exhibits its good power generation capability and resonance frequency tunability.
The impact of buffer thickness upon the transport-limited buffer trapping effects in carbon-doped power GaN-on-Si devices
Authors: Liu Junbo , Zou Wensong , Chen Jiawei , Hua Mengyuan , Lu Di , Ma Jun
Published: September 2023

In this work, we focused on investigating the transport-limited trapping effects in GaN-on-Si buffer layers as well as impact of the thickness of buffer layers (TBuf) upon such effects. Vertical transport dynamics of charges within the buffer layers and their key energy levels are quantitatively and statistically investigated and analyzed. The results show that an increased TBuf diminishes both impurity conduction of the defect band formed by carbon doping as well as the injection of electrons from the substrate, greatly diminishing the current collapse and improving the stability of the device. Such enhancement is mainly attributed to the reduced vertical electric field within the thickened epitaxy, which provides an additional pathway to address the current collapse and yields more efficient power GaN-on-Si devices.
Minimal CSS-supplemented subgroups of finite groups
Authors: Mahboob Abid , Hussaain Taswer , Abbas Tasawar , Bonyah Ebenezer , Khan Muhammad Saad , Almohsen Bandar , Fatima Maheen , Ahmad Hijaz , Ahmad Zubair
Published: September 2023

Over the years, group theorists have evaluated the impact of studying supplemented subgroups on the theory of finite groups. As a result, they have described dozens of criteria for nilpotency and solubility that depend on various supplemented embedded classes of subgroups. In keeping with this approach, we have also established a new concept of CSS-supplemented subgroups. A subgroup H of a group G is described as a CSS-supplemented subgroup in G if T ⊵ G such that G = HT and H ∩ T is SS-supplemented in G. A subgroup H of G is known as an SS-supplemented subgroup in G if there is a subgroup T of G such that HT = G and H ∩ T is SS-quasinormal in T. The SS-supplemented subgroup is expanded based on this agreement by the CSS-supplemented subgroup. By describing new criteria involving formation, we have examined the minimal CSS-subgroup of G based on the structure of the SS-supplemented subgroup that affected p-solubility and p-nilpotency.
Multistable dynamics and attractors self-reproducing in a new hyperchaotic complex Lü system
Authors: Gu Yujuan , Li Guodong , Xu Xiangliang , Song Xiaoming , Wu Si
Published: September 2023

Multistable dynamics analysis of complex chaotic systems is an important problem in the field of chaotic communication security. In this paper, a new hyperchaotic complex Lü system is proposed and its basic dynamics are analyzed. Owing to the introduction of complex variables, the new system has some structurally distinctive attractors, such as flower-shaped and airfoil-shaped attractors. In addition, the evolution process of the limit cycle is also investigated. Next, the multistable coexistence behavior of the system is researched by the method of attraction basins, and the coexistence behavior of two types of hyperchaotic attractors and one type of chaotic and periodic attractors of the system are analyzed. The coexisting hyperchaotic attractors also show flower and airfoil shapes, and four types of coexistence flower-shaped attractors with different structures are perfectly explored. Moreover, the variation of coexistence attractors in the plane and space with parameters is discussed. Then, by introducing a specific piecewise function determined by a two-element method into the new high-dimensional system, the self-reproduction of the attractor can be realized to generate the multistability, and the general steps of attractors self-reproducing in the higher dimensional system are given. Finally, the circuit design of the new system is implemented, which lays a foundation for the application of complex chaotic systems.
Atomistic insight into the shock-induced bubble collapse in water
Authors: Rawat Sunil , Mitra Nilanjan
Published: September 2023

Atomistic simulations are employed to investigate the dynamics of shock-induced bubble collapse in water. Two types of bubbles (an empty bubble and a bubble filled with N2 gas) in water are considered in this study. Apart from the manifestation of a rise in temperature and pressure due to implosion energy released upon bubble collapse; distinct differences in response could be observed for the case of empty bubble to that of the case of the bubble with N2 gas. It is observed that the mechanism of the bubble associated with bubble dissociation as well as the time taken for collapse are changed with the introduction of N2 gas within the bubble. Numerous new chemical species are also observed as the N2 within the bubble reacts with water molecules upon shock compression which can be correlated with the differences in observation between an empty bubble system and a system containing N2 gas. This study is anticipated to lead to further improvements in continuum theories for cavitation bubble collapse in which the effects of chemical reactions need to be incorporated.
Gamma-flash generation in multi-petawatt laser–matter interactions
Authors: Hadjisolomou P. , Jeong T. M. , Kolenaty D. , Macleod A. J. , Olšovcová V. , Versaci R. , Ridgers C. P. , Bulanov S. V.
Published: September 2023

The progressive development of high power lasers over the last several decades enables the study of γ-photon generation when an intense laser beam interacts with matter, mainly via inverse Compton scattering at the high intensity limit. γ-ray flashes are a phenomenon of broad interest, drawing the attention of researchers working in topics ranging from cosmological scales to elementary particle scales. Over the last few years, a plethora of studies predict extremely high laser energy to γ-photon energy conversion using various target and/or laser field configurations. The aim of this article is to discuss several recently proposed γ-ray flash generation schemes, as a guide for upcoming γ-photon related experiments and for further evolution of the presently available theoretical schemes.
Heterovalent cation-exchange of CsPbBr3 perovskite nanocrystals with enhanced stability for x-ray imaging
Authors: Li Yuwei , Xu Yalun , Yao Fang , Lin Qianqian
Published: September 2023

Metal halide perovskites have emerged as promising candidates for x-ray detection; in particular, the in-direct detectors based on perovskite scintillators have demonstrated appealing performance metrics. However, both perovskite thin films and nanocrystals still suffer from poor stability. In this work, we introduce a heterovalent cation exchange strategy to effectively modulate the optoelectronic properties of perovskite nanocrystals and further enhance their stability. Here, a portion of Pb2+ in perovskite nanocrystals was replaced with lead-free Sb3+. This is a versatile method that can be applied to cation exchange of various perovskite nanocrystals, such as CsPbX3 and FAPbX3, allowing for the synthesis of a wide range of mixed-cation perovskite compositions. The resulting nanocrystals exhibit relatively high photoluminescence quantum yields and improved thermal stability and water resistance. The Sb@CsPbBr3 nanocrystals also demonstrated great potential for x-ray detection as scintillators with fast response, bright and radioluminescence, and excellent image quality.
Efficient micromagnetic–elastic simulations based on a perturbed Lagrangian function
Authors: Reichel Maximilian , Niekamp Rainer , Schröder Jörg
Published: September 2023

Micromagnetic simulations require the numerically challenging preservation of the Euclidean norm during the whole simulation. This can be accomplished by applying a priori length preserving methods, renormalization algorithms, or penalization strategies. The latter one includes both the penalty method and the Lagrangian multiplier. The penalty method requires the definition of a penalty parameter during the initiation of the simulation which, depending on its size, can lead to an unsatisfied constraint or stiff and difficult to solve systems of equations. The Lagrange multiplier always penalizes in problem-dependent intensity, hence, an additional degree of freedom is added to the system of equations to the drawback of higher computational costs. This paper proposes a method that utilizes a perturbed Lagrangian multiplier and an element level static condensation to condensate the additional degree of freedom. This guarantees fast simulations, and no parameter fitting in advance. Suitable numerical examples are conducted to prove the workability of the outlined scheme and to highlight the efficiency compared to the non-condensed formulation.
Real-time spatiotemporal characterization of mechanics and sonoporation of acoustic droplet vaporization in acoustically responsive scaffolds
Authors: Aliabouzar Mitra , Abeid Bachir A. , Kripfgans Oliver D. , Fowlkes J. Brian , Estrada Jonathan B. , Fabiilli Mario L.
Published: September 2023

Phase-shift droplets provide a flexible and dynamic platform for therapeutic and diagnostic applications of ultrasound. The spatiotemporal response of phase-shift droplets to focused ultrasound, via the mechanism termed acoustic droplet vaporization (ADV), can generate a range of bioeffects. Although ADV has been used widely in theranostic applications, ADV-induced bioeffects are understudied. Here, we integrated ultra-high-speed microscopy, confocal microscopy, and focused ultrasound for real-time visualization of ADV-induced mechanics and sonoporation in fibrin-based, tissue-mimicking hydrogels. Three monodispersed phase-shift droplets—containing perfluoropentane (PFP), perfluorohexane (PFH), or perfluorooctane (PFO)—with an average radius of ∼6 μm were studied. Fibroblasts and tracer particles, co-encapsulated within the hydrogel, were used to quantify sonoporation and mechanics resulting from ADV, respectively. The maximum radial expansion, expansion velocity, induced strain, and displacement of tracer particles were significantly higher in fibrin gels containing PFP droplets compared to PFH or PFO. Additionally, cell membrane permeabilization significantly depended on the distance between the droplet and cell (d), decreasing rapidly with increasing d. Significant membrane permeabilization occurred when d was smaller than the maximum radius of expansion. Both ultra-high-speed and confocal images indicate a hyper-local region of influence by an ADV bubble, which correlated inversely with the bulk boiling point of the phase-shift droplets. The findings provide insight into developing optimal approaches for therapeutic applications of ADV.
Defect-dependent mechanical and electrical properties of laser-processed CuO nanowires
Authors: Soleimani Maryam , Duley Walter , Zhou Y. Norman , Peng Peng
Published: September 2023

Narrow bandgap p-type semiconducting metal oxide nanowires (NWs), such as copper oxide (CuO), have gained significant attention for their potential in the development of electrical nano-devices. Tailoring the mechanical and electrical properties of CuO NWs is crucial for optimizing their functionality in specific applications. In this study, we employ nanosecond laser irradiation to precisely modify the properties of individual CuO NWs by inducing point and line defects, including oxygen vacancies and dislocations. Through controlled laser irradiation, we observe a gradual enhancement in the concentration of oxygen vacancies within CuO NWs until reaching a saturation point. The accumulation of vacancies leads to a substantial residual stress, resulting in lattice distortion and misfit. This high residual stress serves as a catalyst for the nucleation of dislocations, subsequently leading to a meaningful enhancement in plasticity. Remarkably, the density of dislocations demonstrates a strong correlation with the duration of laser irradiation. Prolonged irradiation leads to a thermally activated restoration process, where the dislocation configuration transitions from a random distribution to ordered dislocation loops. Mechanical characterization tests indicate that pristine CuO NWs exhibit brittleness, while laser irradiation renders them ductile with improved plasticity. Furthermore, the laser processing of CuO NWs demonstrates an enhancement in their electrical conductivity and optical absorbance.
Spontaneous Raman scattering from vibrational polaritons is obscured by reservoir states
Authors: Cohn Bar , Filippov Tikhon , Ber Emanuel , Chuntonov Lev
Published: September 2023

Vibrational strong coupling results from the interaction between optically allowed molecular vibrational excitations and the resonant mode of an infrared cavity. Strong coupling leads to the formation of hybrid states, known as vibrational polaritons, which are readily observed in transmission measurements and a manifold of the reservoir states. In contrast, Raman spectroscopy of vibrational polaritons is elusive and has recently been the focus of both theoretical and experimental investigations. Because Raman measurements are frequently performed with high-numerical aperture excitation/collection optics, the angular dispersion of the strongly coupled system must be carefully considered. Herein, we experimentally investigated vibrational polaritons involving dispersive collective lattice resonances of infrared antenna arrays. Despite clear indications of the strong coupling to vibrational excitations in the transmission spectrum; we found that Raman spectra do not bear signatures of the polaritonic transitions. Detailed measurements indicate that the disappearance of the Raman signal is not due to the polariton dispersion in our samples. On the other hand, the Tavis–Cummings–Holstein model that we employed to interpret our results suggests that the ratio of the Raman transition strengths between the reservoir and the polariton states scales according to the number of strongly coupled molecules. Because the vibrational transitions are relatively weak, the number of molecules required to achieve strong coupling conditions is about 109 per unit cell of the array of infrared antennas. Therefore, the scaling predicted by the Tavis–Cummings–Holstein model can explain the absence of the polariton signatures in spontaneous Raman scattering experiments.
An open-source anisotropic k−ε−v2−f model for turbulent viscoelastic duct flows
Authors: McDermott M. , Riou T. A. E. , Resende P. R. , Wilson M. C. T. , Afonso A. M. , de Boer G.
Published: September 2023

A novel open-source anisotropic k−ε−v2−f model is presented for turbulent viscoelastic duct flow with dilute polymeric solutions described by the finitely extensible nonlinear elastic-Peterlin constitutive model. The turbulence model for channel and square duct flow of Newtonian fluids is adapted to incorporate the polymeric terms within the governing equations. All the required non-linear terms are validated with simple closure models and are assessed a priori against independent direct numerical simulation data in fully developed channel flow. The NLTij term, which accounts for the interaction between fluctuating components of the conformation tensor and the velocity gradient tensor, is modeled with the mean flow direction, ti, and wall-normal, ni, present in the Newtonian model, based on the streamwise alignment of mean polymer stretch. The implicit polymer effects on pressure–strain are assessed with a simple ad hoc closure accounting for the reduced near-wall production of turbulent kinetic energy. The same closure is also adapted for the spanwise Reynolds stress predictions of polymer-enhanced secondary flow. The model performs well in channel flow and captures low, intermediate, and high drag reduction features for a wide range of rheological parameters. The capabilities are extended for square ducts (or any regular polygon) due to the symmetric modeling of the closure models, which can predict the mean streamwise and secondary flow features associated with second normal Reynolds stress differences. Accessible codes and models are crucial for the advancement and improvement of turbulent viscoelastic models, and an OpenFOAM C++ code package is developed and freely available on GitHub (https://github.com/MikeMcDermott-Code/v2f).
Effects of shear strain on HZO ferroelectric orthorhombic phases
Authors: Chen Yun-Wen , Liu C. W.
Published: September 2023

The stabilities of hafnium and zirconium oxide ferroelectric orthorhombic phases, oIII-phase (Pca21) and oIV-phase (Pmn21), under shear strain are investigated theoretically by atomic modeling with density functional theory calculations. The results indicate that oIV-phase serves as a buffer state preventing oIII-phase from transforming into m-phase (P21/c) under structural distortion caused by shear strain and meanwhile preserves the remanent polarization to some certain degree. Shear strain will also induce the reduction in coercive field of the HZO film due to the distortion of oIII-phase or phase transition into oIV-phase. It is very possible to identify oIV-phase with careful analysis of high-resolution transmission electron microscopy and high-angle annular dark-field STEM images at the region having a crystal tilt angle smaller than 86°.
Large amplitude oscillatory shear rheo-NMR velocimetry
Authors: Jayaratne Jayesha S. , Codd Sarah L. , Al-Kaby Rehab N. , Maley Josephine , Brox Timothy I. , Galvosas Petrik , Seymour Joseph D.
Published: September 2023

Complex fluids display flow heterogeneities and a variety of nonlinearities under large amplitude oscillatory shear (LAOS). LAOS has developed as a means of characterizing nonlinear fluid rheology. In this study, the spatial velocity distribution during LAOS is measured by rheo-nuclear magnetic resonance (Rheo-NMR) velocimetry. Rheo-NMR is frequently used to measure responses of complex fluids to steady shear deformations by imaging local velocity across a fluid gap noninvasively. Rheo-NMR analysis of oscillatory flow has been more limited due to hardware limitations. Recently developed Rheo-NMR equipment makes LAOS Rheo-NMR possible. LAOS Rheo-NMR provides measurement of spatial velocity profiles as a function of oscillatory period, providing time dependent spatially resolved local velocity time series, which show distinct features dependent on material response.
Oxygen vacancies and local amorphization introduced by high fluence neutron irradiation in
β
-Ga2O3 power diodes
Authors: Liu Jinyang , Han Zhao , Ren Lei , Yang Xiao , Xu Guangwei , Hao Weibing , Zhao Xiaolong , Yang Shu , Lu Di , Han Yuncheng , Hou Xiaohu , Long Shibing
Published: September 2023

Beta phase gallium oxide (β-Ga2O3) is emerging as a promising material for space applications due to its unique properties and potential high performance in extreme environments. In this work, we systematically study the impact of β-Ga2O3 Schottky barrier diodes (SBDs) under a high fluence neutron irradiation to explore the degradation mechanism of the devices. After irradiated by neutrons with an average energy of 1–2 MeV and a dose rate of 1.3 × 1012 cm−2 s−1, SBDs with a homoepitaxial layer suffered serious performance degradation. The main manifestation of this degradation was a substantial increase in on-resistance, which rose from 3.9 to 3.5 × 108 mΩ·cm2 under the aforementioned irradiation conditions. The appearance of amorphous/polycrystalline striped lattice damage in the epitaxial layer as well as the presence of deep-level defects caused by oxygen vacancies are factors related to this phenomenon. The simulation revealed that the capture reaction of neutrons and Ga elements is the primary cause of neutron irradiation. This reaction generates high-energy beta- particles (β-particles) resulting in the formation of defects. This paper reveals the degradation mechanism of β-Ga2O3 SBDs under neutron irradiation and provides a possible design roadmap for radiation-resistant β-Ga2O3 power devices. Moreover, a high-temperature oxygen annealing process was implemented, which proved to be in restoring the device performance.
An integrated high-flux cold atomic beam source for strontium
Authors: Li Jie , Jia Zhi-Peng , Liu Peng , Liu Xiao-Yong , Wang De-Zhong , Kong De-Quan , Li Su-Peng , Cui Xing-Yang , Dai Han-Ning , Chen Yu-Ao , Pan Jian-Wei
Published: September 2023

We present the design, construction, and characterization of an integrated cold atomic beam source for strontium (Sr), which is based on a compact Zeeman slower for slowing the thermal atomic beam and an atomic deflector for selecting the cold flux. By adopting arrays of permanent magnets to produce the magnetic fields of the slower and the deflector, we effectively reduce the system size and power compared to traditional systems with magnetic coils. After the slower cooling, one can employ additional transverse cooling in the radial direction and improve the atom collimation. The atomic deflectors employ two stages of two-dimensional magnetic-optical trapping (MOT) to deflect the cold flux, whose atomic speed is lower than 50 m/s, by 20° from the thermal atomic beam. We characterize the cold atomic beam flux of the source by measuring the loading rate of a three-dimensional MOT. The loading rates reach up to 109 atoms/s. The setup is compact, highly tunable, lightweight, and requires low electrical power, which addresses the challenge of reducing the complexity of building optical atomic clocks and quantum simulation devices based on Sr.
On the surface flow patterns and associated aerodynamics of an asymmetrical flat-box section
Authors: Li Huan , Peng Rui , Hu Liang , He Xuhui , Kareem Ahsan
Published: September 2023

In this study, wind tunnel experiments were carried out in smooth flow to examine the nexus between flow patterns around a flat-box section and its aerodynamics with the variation of the wind angle of incidence (α). The model cross section closely represents the overall asymmetric geometry and attendant aerodynamics of a class of flat-box decks frequently employed in long-span bridges. To explore the flow around and associated aerodynamic properties of this model that are distinct from a typical symmetric section (e.g., rectangular), detailed wind tunnel tests involving smoke-wire based flow visualizations and synchronous multipoint pressure measurements were carried out. Experimental results were analyzed to identify flow patterns, pressure distributions and associated Strouhal numbers, power spectral densities, aerodynamic force coefficients, proper orthogonal decomposition (POD) analyses, and span-wise correlation. Three typical flow patterns previously observed around symmetric bluff bodies with varying α were also observed in the asymmetric cross section, i.e., the trailing-edge vortex shedding (TEVS), the impinging leading-edge vortices (ILEV), and the alternate-edge vortex shedding (AEVS). However, due to the chordwise asymmetry of the section, the three flow patterns identified are distinct from the classical ones associated with symmetric sections in terms of flow separation points, the static “stall” angle of the section, and characteristics of leading-edge vortices. The roles played by these flow patterns in the aerodynamics of the flat-box section have been identified. It is observed that, if the ILEV or AEVS governs the flow topology, the aerodynamic force coefficients vary nonlinearly with the increase in α, in contrast with the linear variation in the TEVS-dominant case. For cases in which the TEVS dominates, the POD mode participation factors of the fluctuating pressure field display energy in higher modes. In this case, the reconstruction process requires that higher POD modes are retained. Finally, in the TEVS flow pattern, a weaker spanwise correlation of the fluctuating forces is noted as compared to the ILEV and AEVS-type flows. This study is limited to the fundamental examination of asymmetric section aerodynamics in smooth flows, which should be extended in case the influences of turbulence and aeroelastic effect are of interest.
The unexpected diffuse phase transition in relaxor-PbTiO3 ferroelectrics via acceptor modification
Authors: Qi Xudong , Li Kai , Cheng Xue , Zheng Huashan , Sun Enwei , Zhang Rui
Published: September 2023

The diffuse phase transition (DPT) and domain structure are essential to the functional properties of relaxor ferroelectrics and are extremely sensitive to the ion doping. The utilization of acceptor doping has been observed to be an effective method in enhancing the high-power properties of relaxor ferroelectric materials. The present study aims to examine the acceptor-doped DPT and domain structure in single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3. An unexpected physical phenomenon was identified in which Mn-doping increased dielectric diffusion and lowered domain size while suppressing dielectric relaxation. Traceability investigations suggest that Mn-doping inhibited the growth of polar nanoregions by enhancing random electric fields, which increases dielectric diffusion while decreasing the domain size. Meanwhile, Mn doping redistributes the relaxation time function, which results in a reduction in dielectric relaxation. The current research deepens the understanding of the physical basis of DPT and can be applied to the development of high-performance piezoelectric materials.
Infrared spectroscopy of cations in helium nanodroplets
Authors: Singh Amandeep , Bergmeister Stefan , Azhagesan Andrew , Scheier Paul , Vilesov Andrey F.
Published: September 2023

Here, we describe our pulsed helium droplet apparatus for spectroscopy of molecular ions. Our approach involves the doping of the droplets of about 10 nm in diameter with precursor molecules, such as ethylene, followed by electron impact ionization. Droplets containing ions are irradiated by the pulsed infrared laser beam. Vibrational excitation of the embedded cations leads to the evaporation of the helium atoms in the droplets and the release of the free ions, which are detected by the quadrupole mass spectrometer. In this work, we upgraded the experimental setup by introducing an octupole RF collision cell downstream from the electron impact ionizer. The implementation of the RF ion guide increases the transmission efficiency of the ions. Filling the collision cell with additional He gas leads to a decrease in the droplet size, enhancing sensitivity to the laser excitation. We show that the spectroscopic signal depends linearly on the laser pulse energy, and the number of ions generated per laser pulse is about 100 times greater than in our previous experiments. These improvements facilitate faster and more reproducible measurements of the spectra, yielding a handy laboratory technique for the spectroscopic study of diverse molecular ions and ionic clusters at low temperature (0.4 K) in He droplets.