bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of the space weathering timescale on (25143) Itokawa: Implications on its rejuvenation process
Authors: Jin Sunho , Ishiguro Masateru
Published: September 2022

Context. The space weathering timescales of near-Earth S-type asteroids have been investigated using several approaches (i.e., experiments, sample analyses, and theoretical approaches), yet there are orders of magnitude differences.

Aims. We aim to examine the space weathering timescale on a near-Earth S-type asteroid, Itokawa, using Hayabusa/AMICA images, and further investigate the evolutional process of the asteroid.

Methods. We focused on bright mottles on the boulder surfaces generated via impacts with interplanetary dust particles (IDPs). We compared the bright mottle size distribution with an IDP flux model to determine the space weathering timescale.

Results. We found that the space weathering timescale on Itokawa’s boulder surfaces is 103 yr (in the range of 102–104 yr), which is consistent with the timescales of space weathering by light ions from the solar wind.

Conclusions. From this result, we conclude that Itokawa’s surface has been weathered rapidly in 103 yr but portions of the surface are exposed due to seismic shaking that was triggered by a recent impact, which created the Kamoi crater.
Food habits and beliefs about Moringa oleifera among South African student mothers: a qualitative study
Authors: Hedhili Amel , Akinyemi Babatope Ebenezer , Otunola Gloria Aderonke , Husson Florence , Valentin Dominique
Published: September 2022

The problems of malnutrition constitute a major challenge in South Africa, particularly affecting the underprivileged populations of the Eastern Cape and Limpopo provinces. The present study aimed to gain an understanding of how to improve the nutritional intake of South African university student mothers and their children by the introduction of Moringa oleifera in their food. Focus Group Discussion was implemented at two previously historically disadvantaged universities with predominantly black student populations, namely the University of Fort Hare and the University of Limpopo. Findings from the participants’ discussion about food habits and barriers to healthy eating show that there is a gap between healthy eating knowledge and eating habits. Despite the high level of awareness of the importance of nutritional intake, most of the study participants and their children consume less healthy foods. Due to the high cost of healthy food and their limited income, student mothers face substantial financial constraints when trying to make healthy changes in their food habits. Moreover, student mothers’ positive beliefs about the nutritional benefits of Moringa are insufficient to encourage its consumption. Finally, student mothers agree about using Moringa as a nutritional supplement. Maize porridge (pap) appears to be the preferred staple food for Moringa supplementation because of its palatability, satiating power, availability, affordability, and ease of preparation.
Evaluation of the irradiation-averaged fission yield for burnup determination in spent fuel assays
Authors: Govers Kevin , Adriaensen Lesley , Dobney Andrew , Gysemans Mireille , Cachoir Christelle , Verwerft Marc
Published: September 2022

In order to derive the burnup of spent nuclear fuel from the concentration of selected fission products (typically the Nd isotopes and 137Cs), their irradiation-averaged fission yields need to be known with sufficient accuracy, as they evolve with the changes in the actinide vector over the irradiation history. To obtain irradiation-averaged values, radiochemists often resort to robust generic methods – i.e., based on simple mathematical relations – that weight the fission yields according to the actinides contributing to fission, without performing core physics calculations. In order to assess the performance of those generic methods, a database of about 30 000 spent nuclear fuel inventories has been constructed from neutron transport and depletion simulations, covering a representative range of fuel enrichment, burnup, assembly designs and reactor types. When testing several existing methods for effective fission yield calculation, some inaccuracies were identified, originating from improper one-group cross-section parameters that do not accurately reflect resonance and self-shielding effects, and too crude approximations in the estimation of the actinide concentration evolution. Revised effective fission and absorption cross-section parameters are then proposed here, as a first improvement to the earlier burnup determination methods. As a second step, a novel method is proposed that reduces the error on their radiation-averaged fission yield values, and hence on burnup, while retaining a straightforward calculation scheme.
Surgery as a Global Health Need
Authors: Diehl Thomas M. , Soto Ernie , Laryea Jonathan A. , Zafar Syed Nabeel
Published: September 2022

Surgical care is now recognized as a fundamental component of universal health coverage. Unfortunately, most of the world is still without access to safe and timely surgical care, including 9 out of 10 people living in low- and middle-income countries (LMICs). Additionally, even in LMICs with sustainable surgical programs, surgical outcomes continue to lag behind those in high-income countries. In this article, we will provide a brief history and introduction to global surgery, an overview of the existing literature on global surgical outcomes, and a discussion surrounding the challenges to building surgical capacity and improving surgical outcomes in LMICs. In addition, we will discuss the existing frameworks for building surgical care into national universal healthcare plans and initiatives striving improve surgical outcomes in LMICs.
Anal Squamous Intraepithelial Lesions and Anal Cancer Management in Low Resource Settings
Authors: Hawkins Alexander T. , Fang Sandy H.
Published: September 2022

A low resource setting (LRS) is defined as a health care system which does not meet the criteria defined by the World Health Organization (WHO) or other national/international organizations in the following areas: infrastructure, materials, and human resources.1 Patients encounter barriers which limit their access to care and services that are considered standard of care. While LRS is most commonly associated with developing countries, it is easy to overlook communities in developed countries which lack the financial resources to afford basic health care. This article describes the societal implications and barriers to care for both squamous intraepithelial lesions (SILs) and anal cancer in LRS, the existing screening/surveillance approaches, available treatment approaches to anal cancer, and it also discusses potential evidence-based approaches to bridge the gap for these disparities in anal cancer care.
Colon and Rectal Cancer Management in Low-Resource Settings
Authors: Boatman Sonja , Nalluri Harika , Gaertner Wolfgang B.
Published: September 2022

Colorectal cancer (CRC) incidence is rising in low- and middle-income countries, which also face disproportionate mortality from CRC, mainly due to diagnosis at late stages. Various challenges to CRC care exist at multiple societal levels in underserved populations. In this article, barriers to CRC care, strategies for screening, and treatment in resource-limited settings, and future directions are discussed within a global context.
Endoscopic Ultrasound-Guided Fine-Needle Biopsy for Pancreatic Lesions is the Way Forward: Here is the Evidence!
Authors: Jha Daya Krishna , Rana Surinder Singh
Published: September 2022

Endoscopic ultrasound-guided tissue acquisition (EUS TA) has increasingly become imperative for pancreatic pathology in arriving at the correct diagnosis because of its simplicity, cost-effectiveness, and availability at high-volume centers. The advent of EUS fine-needle biopsy (FNB) has revolutionized EUS TA by providing samples that are larger and more diagnostic compared with fine-needle aspiration (FNA). Rapid onsite evaluation (ROSE) has been conventionally used for improving the cytological yield as well as diagnostic accuracy of EUS FNA. The development of FNB has obviated the need for ROSE, and evidence from retrospective and comparative studies has suggested that FNB is as good as FNA with ROSE in terms of diagnostic accuracy and reduced costs. However, strong evidence in the form of a randomized controlled trial (RCT) was missing. In this news and views, we discuss a multicenter RCT that has compared the diagnostic accuracy of EUS FNB alone to EUS FNA with ROSE in patients with solid pancreatic lesions. This study has reemphasized that EUS FNB has a diagnostic accuracy comparable to EUS + ROSE at a comparable cost and requires fewer passes and has a shorter procedure time.
Conventional and Investigational Approaches Leveraging Clinical EEG for Prognosis in Acute Disorders of Consciousness
Authors: Curley William H. , Comanducci Angela , Fecchio Matteo
Published: September 2022

Prediction of recovery of consciousness after severe brain injury is difficult and limited by a lack of reliable, standardized biomarkers. Multiple approaches for analysis of clinical electroencephalography (EEG) that shed light on prognosis in acute severe brain injury have emerged in recent years. These approaches fall into two major categories: conventional characterization of EEG background and quantitative measurement of resting state or stimulus-induced EEG activity. Additionally, a small number of studies have associated the presence of electrophysiologic sleep features with prognosis in the acute phase of severe brain injury. In this review, we focus on approaches for the analysis of clinical EEG that have prognostic significance and that could be readily implemented with minimal additional equipment in clinical settings, such as intensive care and intensive rehabilitation units, for patients with acute disorders of consciousness.
Pharmacologic Therapies to Promote Recovery of Consciousness
Authors: Barra Megan E. , Edlow Brian L. , Brophy Gretchen M.
Published: September 2022

Pharmacologic interventions are commonly used to support rehabilitation efforts of patients with disorders of consciousness (DoC). The 2018 practice guidelines recommend amantadine in adults with traumatic DoC to promote functional recovery, though several other stimulants are used off-label in clinical practice and trials, such as methylphenidate, bromocriptine, levodopa, and zolpidem. Differences in the mechanisms of action, adverse effects, pharmacokinetics, and drug–drug interactions should be considered when selecting the best agent for each individual patient. Overall, pharmacologic stimulants may provide a safe and inexpensive pathway to increased functionality and participation in rehabilitation. This article provides a concise summary of scientific evidence supporting the use of pharmacologic therapies to stimulate recovery of consciousness in patients with DoC.
Endoscopic Full Thickness Resection: A Systematic Review
Authors: Pal Partha , Ramchandani Mohan , Inavolu Pradev , Reddy Duvvuru Nageshwar , Tandan Manu
Published: September 2022

Background Endoscopic full thickness resection (EFTR) is an emerging therapeutic option for resecting subepithelial lesions (SELs) and epithelial neoplasms. We aimed to systematically review the techniques, applications, outcomes, and complications of EFTR.

Methods A systematic literature search was performed using PubMed. All relevant original research articles involving EFTR were included for the review along with case report/series describing novel/rare techniques from 2001 to February 2022.

Results After screening 7,739 citations, finally 141 references were included. Non-exposed EFTR has lower probability of peritoneal contamination or tumor seeding compared with exposed EFTR. Among exposed EFTR, tunneled variety is associated with lower risk of peritoneal seeding or contamination compared with non-tunneled approach. Closure techniques involve though the scope (TTS) clips, loop and clips, over the scope clips (OTSC), full thickness resection device (FTRD), and endoscopic suturing/plicating/stapling devices. The indications of EFTR range from esophagus to rectum and include SELs arising from muscularis propria (MP), non-lifting adenoma, recurrent adenoma, and even early gastric cancer (EGC) or superficial colorectal carcinoma. Other indications include difficult locations (involving appendicular orifice or diverticulum) and full thickness biopsy for motility disorders. The main limitation of FTRD is feasibility in smaller lesions (<20–25 mm), which can be circumvented by hybrid EFTR techniques. Oncologic resection with lymphadencetomy for superficial GI malignancy can be accomplished by hybrid natural orifice transluminal endoscopic surgery (NOTES) combining EFTR and NOTES. Bleeding, perforation, appendicitis, enterocolonic fistula, FTRD malfunction, peritoneal tumor seeding, and contamination are among various adverse events. Post OTSC artifacts need to be differentiated from recurrent/residual lesions to avoid re-FTRD/surgery.

Conclusion EFTR is safe and effective therapeutic option for SELs, recurrent and non-lifting adenomas, tumors in difficult locations and selected cases of superficial GI carcinoma.
Endocuff Vision to Improve Adenoma Vision: A Brief Overview
Authors: Shukla Jayendra , Samanta Jayanta
Published: September 2022

Colorectal cancer (CRC)-related mortality can be reduced through screening and early detection. The aim of any CRC screening program is to detect as many adenomas/polyps in the early stage as possible and hence, adenoma detection rate (ADR) is a key quality indicator of colonoscopy. Various methods and techniques have been studied and developed over the years to improve the quality of colonoscopy and thereby increase ADR. This ranges from use of various regimens to improve bowel preparation, defining an optimum colonoscope withdrawal time for the operator, distal attachment caps, use of different wavelength of light, colonoscope with increased degree of view to the use of modern-day artificial intelligence to improve ADR. Of all the various measures, use of distal attachment device seems an easy, cheap and readily usable technique to increase real-time ADR. A variety of such devices have been evaluated over time starting from simple transparent caps, EndoRings, Endocuff to Endocuff Vision for their effectiveness. In this review, we have provided a brief description of the various available distal attachment devices and a detailed technical overview of Endocuff and its modification the Endocuff Vision.
Lieferengpässe wegen Ukraine-Krieg: Mehrlieferanten-Strategie statt Single-Sourcing
Authors: Erxleben Christiane
Published: September 2022

Der russische Angriffskrieg auf die Ukraine lässt das deutsche Gesundheitswesen nicht unberührt. Im Interview berichtet Martin Merkel, Mitglied im Arbeitskreis Strategie und Kommunikation der femak, über die Folgen für die Lieferketten und Auswege aus Krise.
40 Jahre Femak E.V.: Ein Rück- und Ausblick
Authors: Gallmann Thomas
Published: September 2022

Im September 1982 unterzeichneten 17 Teilnehmer in der Gründungsversammlung in Esslingen den Gründungsvertrag der femak. femak war und ist der neutrale und unabhängige Fachverband für die Einkäufer, Materialwirtschaftler und Logistiker; nicht nur im Krankenhaus, sondern für alle Einrichtungen des Gesundheitswesens.
Pandemie: Banger Blick auf den Herbst
Authors: Doelfs Guntram
Published: September 2022

Vom Durchschnaufen konnte in diesem Sommer keine Rede sein. Eine überraschende Corona-Sommerwelle strapazierte die Kliniken enorm, das Personal ist am Ende der Belastungsfähigkeit. Und schon bald dürfte die nächste Welle folgen. Zweifel sind erlaubt, ob das Land nun endlich besser darauf vorbereitet ist.
Infektionsschutzgesetz: Novelle mit vielen Fragezeichen
Authors: Doelfs Guntram
Published: September 2022

Nach langem Gezerre einigten sich Anfang August Gesundheitsminister Prof. Karl Lauterbach (SPD) und Justizminister Marco Buschmann (FDP) auf ein neues Infektionsschutzgesetz. Der Entwurf erntete schnell starke Kritik von den Ländern, der Bundesärztekammer und der DKG. Während viele vorgesehene Regelungen „vage“ oder in der Praxis nicht umsetzbar seien, blieben Datenprobleme weiterhin ungelöst.
Corona: Impfpflicht verpufft ohne große Wirkung
Authors: Heeser Alexandra
Published: September 2022

Seit 16. März gilt die einrichtungsbezogene Impfpflicht in Gesundheitseinrichtungen. Seither müssen Kliniken sowie Alten- und Pflegeheime der jeweiligen Landesbehörde Auskunft über den Genesenen- und Impfstatus ihrer Beschäftigten geben. Konkrete Beschäftigungsverbote oder Strafen gibt es bislang kaum.
Einrichtungsbezogene impfpflicht: Der Nachweis ist Pflicht
Authors: Wiencke Christopher
Published: September 2022

Seit Einführung der einrichtungsbezogenen Impfpflicht im Gesundheitswesen ist fraglich, welche Handlungspflichten Arbeitgeber in diesem Zusammenhang treffen und wie sich dies auf Arbeitnehmerinnen und Arbeitnehmer auswirkt. Erste Gerichtsverfahren wurden bereits geführt – ein Überblick über die aktuelle Rechtslage.
Outsourcing: Richter setzen Kliniken Grenzen
Authors: Birgitta vom Lehn
Published: September 2022

Das Bundessozialgericht hat entschieden, dass relevante Leistungen im Krankenhaus erbracht werden müssen. Inwieweit das Urteil auch die Auslagerung von Serviceleistungen tangiert, steht noch nicht fest. kma hat Stimmen zum Urteil eingefangen.
Hitzeschutz im Krankenhaus: „Wir sind schon gut auf Hitzeperioden vorbereitet“
Authors: Hohnstein Aileen
Published: September 2022

Hitzeschutzpläne in Einrichtungen des Gesundheitswesens sind bislang noch eine Ausnahmeerscheinung. Das Evangelische Krankenhaus Hubertus hat das Thema schon länger im Fokus. kma hat mit dem Hitzeschutzbeauftragten und Geschäftsführer Dr. Matthias Albrecht darüber gesprochen, wie man sich künftig besser gegen Hitzeperioden aufstellen kann.
Textile Dienstleister: Zeitenwechsel in Weiß
Authors: Lang Michael
Published: September 2022

Bei den textilen Dienstleistern herrscht zurzeit Alarmstimmung. Die Preise für Energie und Rohstoffe explodieren, hinzu kommt der Mangel an Gas und an Fachkräften. Krankenhäuser müssen sich auf erhebliche Mehrkosten für ihre Wäsche einstellen.
Nachhaltige Speisenversorgung: Den CO2-Fußabdruck verringern
Authors: Lang Michael
Published: September 2022

Gestiegene Energie- und Lebensmittelpreise machen auch den Catering-Unternehmen zu schaffen. An ihren Nachhaltigkeitszielen möchten sie aber keine Abstriche vornehmen.
Akademisierte Pflege am Bett: APN: Das Uniklinikum Regensburg geht neue Wege
Authors: Dittrich Marc , Stockinger Alfred
Published: September 2022

Der demografische Wandel und die steigende Zahl von Pflegebedürftigen stellt besonders die Pflege vor eine schwierige Aufgabe. Trotz Fachkräftemangel gilt es eine qualitativ hochwertige, effiziente und wirtschaftlich angemessene pflegerische Versorgung sicherzustellen. Ein guter Weg, diesen Anforderungen gerecht zu werden, ist der Einsatz von Advanced Practice Nurses (APN).
Effect of seasonally forced noisy environment on aquatic prey–predator model with water level fluctuations
Authors: Sarkar Abhijit , Sk Nazmul , Pal Samares
Published: September 2022

In this paper, the impact of environmental noise on prey–predator interactions with seasonal fluctuations in water levels has been studied. Both intensity of noise and water level variations together play a significant role in the dynamics of an aquatic prey–predator system. Analytically, we have shown the existence of a positive solution and its uniqueness, the ultimate bound of the system’s solutions, and the global attractivity of the solution. Moreover, parametric conditions for which model species either persist (strongly or weakly) in the system or go into extinction are derived and their biological significance is also discussed. The sufficient condition of stochastic permanence is also analyzed. To justify the analytical results, we have performed numerical simulations of both deterministic and stochastic systems and observed some significant dynamics in the considered system.
Characterization of sub-picosecond laser-produced fast electrons by modeling angularly resolved bremsstrahlung measurements with 3D hybrid particle-in-cell code
Authors: Chen L. , Sawada H.
Published: September 2022

Hard x-rays produced by intense laser-produced fast electrons interacting with solids are a vital source for producing radiographs of high-density objects and implosion cores for inertial confinement fusion. Accurate calculation of hard x-ray sources requires a three-dimensional (3D) simulation geometry that fully models the electron transport dynamics, including electron recirculation and the generation of absolute photon yields. To date, 3D simulations of laser-produced bremsstrahlung photons over tens of picoseconds and code benchmarking have not been performed definitively. In this study, we characterize sub-picosecond laser-produced fast electrons by modeling angularly resolved bremsstrahlung measurements for refluxing and non-refluxing targets using the 3D hybrid particle-in-cell (PIC), Large Scale Plasma code. Bremsstrahlung radiation and escaped electron data were obtained by focusing a 50-TW Leopard laser (15 J, 0.35 ps, 2 × 1019 W/cm2) on a 100-μm-thick Cu foil and a Cu with a large plastic backing (Cu–CH target). Data for both the Cu and Cu–CH targets were reproduced for simulations with a given set of electron parameters. Comparison of the simulations revealed that the hard x-ray emission from the Cu target was significantly longer in duration than that from the Cu–CH target. The benchmarked hybrid PIC code could prove to be a powerful tool in the design and optimization of time- and angular-dependent bremsstrahlung sources for flash x-ray and gamma-ray radiography.
Absolute beam monitor: A novel laboratory device for neutral beam calibration
Authors: Gasser Jonathan , Galli André , Wurz Peter
Published: September 2022

Instruments recording Energetic Neutral Atoms (ENAs) for space applications require thorough laboratory calibration in a dedicated test facility providing a neutral atom beam. Accurate knowledge of the neutral beam intensity and energy is central for the laboratory calibration procedure. However, until recently, the quantification of the neutral atom beam intensity in the low-energy range below a few 100 eV was based on relative measurements with standard detectors of approximately known detection efficiencies for neutral atoms. We report on the design and development of a novel calibration device dedicated to determining the ENA beam flux in an absolute manner in the energy range from 3 keV down to about 10 eV. This is realized by applying ENA scattering at a surface and coincident detection of scattered particles and created secondary electrons. Moreover, the neutral beam energy is determined by a time-of-flight measurement. The applied measurement principle relies on very low background signals. The observed background count rates are in the range 10−2 s for the individual channels and about 10−5 s for coincidence events. The background is, thus, at least two, typically four, orders of magnitude lower than the signal rate for neutral atom beams in the foreseen energy range. We demonstrate a concrete application using the absolute flux calibration of a laboratory neutralization stage.
Tailoring interface epitaxy and magnetism in La1−xSrxMnO3/SrTiO3 heterostructures via temperature-driven defect engineering
Authors: Molinari Alan , Gorji Saleh , Michalička Jan , Kübel Christian , Hahn Horst , Kruk Robert
Published: September 2022

Defect engineering of La1−xSrxMnO3 (LSMO)—a strongly correlated oxide displaying half metallicity and ferromagnetism above room temperature—has been the focus of a long-standing quest aimed at the exploitation of this material as a functional building block for memory storage and spintronic applications. Here, we discuss the correlation between structural defects and magnetism in La0.74Sr0.26MnO3/SrTiO3 (LSMO/STO) epitaxial heterostructures as a function of growth temperature and post-deposition annealing. Upon increasing the growth temperature from 500 to 700 °C at a fixed oxygen partial pressure of 0.007 mbar, the sputter-deposited epitaxial LSMO films experience a progressive increase in Curie temperature Tc from 110 to 270 K and saturation magnetization Ms from 1.4 to 3.3 μB/u.c. owing to a reduction in oxygen deficiencies. Concurrently, however, growth temperatures above 600 °C trigger the formation of off-stoichiometric, dendritic-like SrMoOx islands at the film/substrate interface as a possible aftermath of temperature-driven diffusion of impurities from the STO substrate. Notably, although the interfacial spurious islands cause an increase in sample surface roughness, the heterostructure still preserves high-quality epitaxy. In general, the best compromise in terms of both structural and magnetic properties, comprising high-quality epitaxy, atomically flat surface, and robust ferromagnetism above room temperature, is obtained for LSMO films grown at a relatively low temperature of about 500–540 °C followed by a post-deposition annealing treatment at 900 °C for 1 h in air. Our study compares effective routes based on temperature-controlled defect engineering to finely tailor the complex interplay between microstructure and magnetism in LSMO thin films.
Uniformity evaluation of laser-induced periodic surface structures formed by two-color double-pulse femtosecond laser irradiation
Authors: Takenaka Keisuke , Hashida Masaki , Sakagami Hitoshi , Masuno Shin-ichiro , Kusaba Mitsuhiro , Yamaguchi Shigeru , Iwamori Satoru , Sato Yuji , Tsukamoto Masahiro
Published: September 2022

The Perpendicular Period and Phase Scanning (P3S) method can evaluate the uniformity of a laser-induced periodic surface structure (LIPSS). P3S assesses the uniformity of LIPSS using the standard deviation of the peak period and the average of the phase difference in the direction perpendicular to LIPSS. The P3S method demonstrates that LIPSS formed by two-color double-pulse irradiation is reduced to a quarter of the period dispersion, and the average phase difference of LIPSS is also reduced compared to the single-pulse irradiation. In addition, a 3D electromagnetic particle-in-cell simulation was performed to evaluate the possibility of an improved uniformity of LIPSS. The results confirm that the two-color double-pulse irradiation produces a uniform LIPSS and validates the effectiveness of the P3S method to assess the uniformity of LIPSS.
Numerical analysis of structural change process in millimeter-wave discharge at subcritical intensity
Authors: Suzuki S. , Hamasaki K. , Takahashi M. , Kato C. , Ohnishi N.
Published: September 2022

Plasma-front propagation processes of 170 GHz millimeter-wave discharge were investigated under subcritical incident electric field intensity by using a one-dimensional model. The discharge structure was numerically reproduced at more than 0.2 MV/m by introducing the detailed chemical reaction and radiation transport processes into the conventional model. The results revealed that the propagation mechanism of the plasma front in the millimeter-wave discharge changes depending on the incident electric field intensity. At intensities greater than 1.4 MV/m, the plasma front propagated at supersonic speed, while forming a discrete structure, which has intervals of 1/4 wavelength of the millimeter wave. This structure was generated by electron-impact ionization and photoionization processes. At the intermediate intensities, the plasma front propagated continuously rather than discretely because the gas expansion increased the reduced electric field and induced electron-impact ionization. The dominant heating process at the plasma front was fast gas heating. At intensities less than 0.3 MV/m, the plasma front propagated continuously, but the dominant heating process changed to vibrational–translational relaxation. The discharge was maintained by thermal ionization and associative ionization. The simulation results were in good agreement with the past millimeter discharge experiments at this intensity.
Metallization considerations for carbon nanotube device optimization
Authors: Farmer Damon B.
Published: September 2022

As a one-dimensional structure with atomically thin sidewalls, charge transport in carbon nanotubes can be regarded as a surface phenomenon. As such, perturbations from the surrounding environment can have a dramatic impact on transport and consequently on the device behavior of carbon nanotube field-effect transistors (CNTFETs). Importantly, this includes effects from device fabrication processes like contact metallization. With this as motivation, several aspects of contact metallization are investigated herein. First, it is found that ON current in n-type CNTFETs is enhanced to the level of p-type CNTFETs through the utilization of titanium as an adhesion layer, a result of improved wetting. Effects of different metallization techniques, namely, thermal and electron-beam evaporation, are also explored in p-type devices using titanium/palladium/gold contacts. It is found that thermal metallization consistently produces devices with higher ON current. In-depth analysis of the transfer characteristics reveals that this is due to radiation effects encountered during electron-beam processing, resulting in channel scattering and a decreased transconductance in the devices. This effect is particularly severe upon gold processing, and attempts to heal this device degradation through annealing proved unsuccessful. All studies presented here are conducted through the analysis of a large number of nanotube devices, giving a degree of confidence to the average results. Additionally, only device parameters that can be directly extracted from the transfer characteristics are analyzed. Assumptions including nanotube diameter, capacitance, and nanotube number per device are not made. Results from this study provide recommendations for optimizing CNTFET performance as it relates to contact metallization.
A high-power long lifetime beam dump for the Thomson scattering diagnostic system in the XuanLong-50 experiment
Authors: Liu J. H. , Li S. J. , Li H. Y. , Xie Q. F. , Bai R. H. , Bo X. K. , Deng B. H.
Published: September 2022

The Energy iNNovation’s XuanLong-50 is a spherical torus experiment with up to 10 s plasma operation duration. A 3 J/50 Hz pulsed laser is used in the Thomson scattering diagnostic system that is developed to measure the time evolutions of plasma electron temperature and density profiles. The expected laser pulse number is about 7.5 × 106/year with a power load of 150 W. To meet at least 1-year lifetime requirement, a Chevron type beam dump with polished molybdenum plates is designed and fabricated, which absorbs the laser beam energy in a 3D structure to reduce the laser fluence deposited on the material surface. To prevent the backscattered stray light from interfering with the Thomson scattering measurements, a 7.5 m beam path with folding mirrors is set between the beam dump and the plasma scattering volumes. Details of the beam dump design procedure including the laser beam profile control, multi-pulse laser damage threshold, heat dissipation, Zemax modeling, folding mirror selection, and beam path enclosure are presented together with the testing results.
The optical diagnosis of electrical wire explosion under a microsecond current pulse
Authors: Meng Yang , Tang Meng yuan , Xue Haruki , Ding Weidong , Zhang Youngman , Wang Yana
Published: September 2022

Electrical wire explosions have many applications in scientific research and industry. Optical diagnosis is a powerful method to clarify the evolutionary process of such explosions. In this paper, an experimental platform was established to diagnose the optical radiation of electrical wire explosions. A low-jitter trigatron switch and its trigger generator were designed to ensure accurate synchronization. The spatial–temporal evolution process and the self-emission spectrum of electrical explosion plasmas from different wires (copper and tantalum) were obtained and analyzed. The optical diagnosis results indicated that the electrical explosion of copper wire was mainly characterized by the inhomogeneity of partial ionization and the rapid expansion of the discharge channel. The spectrum in the early discharge stage of the copper wire electrical explosion was a continuum, and most of the self-radiation spectral lines belonged to Cu I or Cu II. At the later stage of the plasma dissipation process, the continuous spectrum gradually transformed into a line spectrum. The development of the tantalum wire discharge channel was relatively uniform, and the plasma was mainly established in the gas–liquid mixed phase channel of the tantalum wire. The self-emission spectrum of the tantalum wire was always continuous, and the absorption process of line spectrum radiation was distinct.
Low thermal conductivity in A-site high entropy perovskite relaxor ferroelectric
Authors: Xiong Wei , Zhang Hangfeng , Hu Zimeng , Reece Michael J , Yan Haixue
Published: September 2022

An A-site disordered high entropy perovskite (Pb1/6Ba1/6Sr1/6Ca1/6Na1/6Bi1/6)TiO3 (PBSCNBi) ceramic was prepared by a solid-state reaction method. XRD and scanning electron microscopy-energy dispersive x ray confirmed a single-phase tetragonal solid solution. Dielectric and hysteresis loop measurements showed relaxor ferroelectricity at room temperature; Curie Weiss fitting gives a Burns temperature (Tb) of 123 °C, and Vogel–Fulcher fitting gives a freezing temperature (Tf) of −67.24 °C, which confirms the room-temperature relaxor ferroelectricity of PBSCNBi. This is attributed to local chemical inhomogeneities in the high entropy ceramics. PBSCNBi also has a low thermal conductivity (1.15 W m−1 K−1 at room temperature) compared to all of its constituent simple perovskites (e.g., BaTiO3, PbTiO3, SrTiO3 CaTiO3, and Na1/2Bi1/2TiO3 in the range of 25–100 °C), which is attributed to the enhanced phonon scattering by both polar nanoregions and the mass contrast effect in the multi-element perovskite. This work demonstrates the great potential of making A-site high entropy ceramics with relaxor ferroelectric properties.
Prospects of federated machine learning in fluid dynamics
Authors: San Omer , Pawar Suraj , Rasheed Adil
Published: September 2022

Physics-based models have been mainstream in fluid dynamics for developing predictive models. In recent years, machine learning has offered a renaissance to the fluid community due to the rapid developments in data science, processing units, neural network based technologies, and sensor adaptations. So far in many applications in fluid dynamics, machine learning approaches have been mostly focused on a standard process that requires centralizing the training data on a designated machine or in a data center. In this article, we present a federated machine learning approach that enables localized clients to collaboratively learn an aggregated and shared predictive model while keeping all the training data on each edge device. We demonstrate the feasibility and prospects of such a decentralized learning approach with an effort to forge a deep learning surrogate model for reconstructing spatiotemporal fields. Our results indicate that federated machine learning might be a viable tool for designing highly accurate predictive decentralized digital twins relevant to fluid dynamics.
Single-beam integrated hybrid optical pumping spin exchange relaxation free magnetometer for biomedical applications
Authors: Ma Yintao , Qiao Zhixia , Yu Mingzhi , Wang Yanbin , Chen Yao , Luo Guoxi , Yang Ping , Lin Qijing , Zhao Libo , Zhang Yun , Sun Junjie , Qin Guangzhao , Jiang Zhuangde
Published: September 2022

An ingenious approach to accomplish the high signal strengthen and relatively homogeneous spin polarization has been presented in a hybrid optical pumping spin-exchange-relaxation-free atomic magnetometer only utilizing single-beam configuration. We have experimentally demonstrated an approximately three-fold enhancement of the output signal at the optimal spin polarization by optically pumping the thin vapor due to the same spin evolution behavior of the two different kinds of vapor atoms. Eventually, a measuring sensitivity of 30 fT/Hz1/2 was achieved combined with the homemade differential detection system for attenuating large background offset and suppressing optical power noise. This scheme provides a prospect for the development of ultra-highly sensitive and chip-scale atomic magnetometer for the applications that desire both high signal-to-noise ratio and uniform spin polarization, such as magnetocardiography and magnetoencephalography.
Numerical and experimental investigation of gas–gas diffusion and convection
Authors: Lyu Wenjing , Kim Sedong , Delgado Antonio , Gatternig Bernhard , Troeger Klaus , Schellin Thomas
Published: September 2022

Gas-to-gas diffusion and convection phenomena exist in a wide range of applications, including industrial and scientific processes, food production and storage, and breathing gases. To analyze gas–gas mixing phenomena, a numerical model based on open-source tool libraries was developed and validated; an experimental model was built up and repeated physical tests were performed. Comparative mixing gas–gas profiles and O2 concentration time histories were presented to analyze gas–gas phenomena and to validate the developed numerical solver. Practically, relevant assessments of the gas-to-gas diffusion and convection process demonstrated that (1) obstacles accelerated gas–gas diffusion and convection, (2) diffusion and convection stabilized after a certain time period, and (3) stronger diffusion and convection occurred during the initial stages of the gas-to-gas contact.
Effects of the preferential adsorption in a near-critical binary fluid mixture on dynamics of a droplet
Authors: Fujitani Youhei
Published: September 2022

A large amount of binary fluid mixture in the homogeneous phase near the demixing critical point can include a small spherical droplet of a third fluid-component confined by a sharp interface. Conversely, a droplet consisting of the mixture can be immersed in the third fluid-component. In either of the situations, we assume that the third component attracts one mixture component more than the other via short-range interactions. The adsorption layer, enriched with the preferred component, appears on the mixture side of the interface and can thicken significantly because of large susceptibility. The preferential adsorption affects flows, causing the drag coefficient to deviate. We use the hydrodynamics based on a coarse-grained free-energy functional to calculate the deviation, while neglecting the weak singularity of mixture viscosity. When the mixture lies inside the droplet, the ratio of the deviation changes nonmonotonically as the ratio of the ambient viscosity to the droplet viscosity increases. When the mixture lies outside, the deviation ratio increases with the viscosity ratio and can be considerably larger for a droplet than for a rigid sphere. Then, if a composition gradient is imposed, a force-free droplet undergoes diffusiophoresis, whose mobility can be considerably larger in magnitude than that of a rigid sphere. These results can be utilized in future applications in the droplet microfluidics. We also discuss probable power-law dependences of the drag coefficient and the mobility on the reduced temperature. The suggested power for the mobility is connected with the universal order-parameter profile in the surface critical behavior.
Flow leakage and Kelvin–Helmholtz instability of turbulent flow over porous media
Authors: Jadidi Mohammad , Param Hanieh Khalili , Revell Alistair , Mahmoudi Yasser
Published: September 2022

In the present paper, turbulent flow in a composite porous–fluid system, including a permeable surface-mounted bluff body immersed in a turbulent channel flow, is investigated using pore-scale large eddy simulation. The effect of Reynolds number (Re) on the flow leakage from porous to non-porous regions, Kelvin–Helmholtz (K–H) instabilities, as well as coherent structures over the porous–fluid interface are elaborated by comparing cases with three Reynolds numbers (Re = 3600, 7200, and 14 400). Results show that more than 52% of the fluid entering the porous blocks leaks from the first half of the porous region to the non-porous region through the porous–fluid interface. As the Re number increases from 3600 to 14 400, the flow leakage decreases by 24%. Flow visualization shows that the Re number affects the size of counter-rotating vortex pairs (CRVPs) and coherent hairpin structures above the porous block. At the Re = 3600, the CRVPs are larger and their centers locate farther away from the porous–fluid interface at Y/D ∼ 0.3 (D is two times of the distance between the centers of two consecutive pores), while at the highest Re number (Re = 14 400), they are 200% smaller and their centers become closer to the interface at Y/D ∼ 0.1. Moreover, turbulence statistics show that by reducing the Re number, turbulence production is delayed downstream; at the Re = 14 400, it begins from the leading edge of the porous block (X/D = 0), while at the Re = 3600, turbulence production is postponed and starts nearly at the middle of the porous block (X/D = 4.6). Also, quadrant-hole analysis indicates that increasing the Re number from 3600 to 14 400 strengthens sweep events and submerses the legs of coherent hairpin structures into the interface. Finally, the distribution of the pressure gradient for the three Re numbers confirms the occurrence of the K–H instability vortices over the porous–fluid interface. For Re = 3600, the K–H instability vortices show a linear growth rate in the vertical and horizontal directions with the slope of 0.136 and 0.05, respectively. However, by increasing the Re from 3600 to 14 400, the growth rate slope in the horizontal direction decreases by nearly 33.8%, while in the vertical direction, it increases by 200%.
Evolution of electro-induced blood plasma droplets on a superhydrophobic microstructured surface
Authors: Li Kaikai , Xie Yingxi , Tang Biao , Yu Min , Ding Huanwen , Li Chunbao , Lu Longsheng
Published: September 2022

Formation of severe adhesion on electrosurgical devices during their interaction with biofluids is an inherent problem that often causes reduced cutting efficiency and failed hemostasis. The introduction of (super-) hydrophobic surfaces is a favorable option for anti-adhesion, but the mechanisms related to their evolution with biofluids under electric fields are still not fully understood. Here, we investigated the evolution of blood plasma droplets on a superhydrophobic microstructured (SHM) surface under direct-current (DC) and alternating-current (AC) electric fields. The electrolysis of plasma droplets leads to the formation and diffusion of bubbles accompanied by a rise in temperature, while in turn, the electrolysis is suppressed as the bubbles fill the droplets, followed by a decrease in temperature. We show that under the DC electric field, the bubbles produced by papillae on the SHM surface can effectively prevent directional adsorption of plasma proteins compared to the flat surface, whereas the AC electric field induces oscillations in plasma proteins, resulting in even less adhesion. These findings provide valuable basic information for understanding the anti-adhesion mechanism of electrosurgical devices at a microscopic level.
Study of flow through and around a pair of porous cylinders covering steady and unsteady regimes
Authors: Jamshed Saqib , Kharbanda Rohit , Dhiman Amit Kumar
Published: September 2022

The present article focuses on the incompressible flow around two identical porous cylinders for a side-by-side configuration in a closed channel. The formation of various flow patterns behind permeable cylinders is more intriguing and further compelling to assimilate the underlying flow physics. The effects of three critical parameters, gap ratio (s/d), Reynolds number (Re), and the Darcy number (Da), on the flow behavior are investigated for the ranges of s/d = 1.5–6, Re = 5–100, and Da = 10−6–10−2. Both attached standing and detached vortices are observed in a steady flow regime. One secondary wake structure is also observed for s/d = 1.5, whose size gradually reduces with increased permeability. In an unsteady flow regime, the jet-like flow in the gap section mainly governs the unsteady wake patterns. In the low range of Darcy numbers (10−6–10−3), asymmetric flip-flopping patterns are observed for s/d = 1.5 and 2; and synchronized wake patterns either in anti-phase or in-phase mode are observed for higher gap ratios. The velocity profiles in the gap and free sides of the cylinders and pressure distribution along the porous surface are also discussed to facilitate the understanding of different wake patterns. Surprisingly, a case of pattern shifting from anti-phase to in-phase mode is observed when permeability is altered for the same flow-time. Symmetric and clustered strands of vorticity near the centerline are observed for all cases of s/d at Da = 10−2. The effects of Re, s/d, and Da on the drag coefficient and critical Reynolds number are also discussed. A jump in the drag values, a maximum of 13.9% for s/d = 3.5, is witnessed for the mid-range of Da at higher Re.
Heat transfer analysis of immiscible slug flow-based microchannels: Study of channels with extended surfaces
Authors: Soleimani Rasa , Azaiez Jalel , Zargartalebi Mohammad , Gates Ian D.
Published: September 2022

Immiscible injection of slug(s) into a microchannel with square blocks attached to the bottom surface of the channel is studied using the phase-field approach for interface tracking. It is confirmed that immiscible injection enhances heat transfer by up to 85% compared to miscible injection considering identical thermophysical properties. The differences in the rate of heat removal between immiscible and miscible injection are explained by the hydrodynamics of the system. It is also found that larger injected slug size does not necessarily result in greater heat removal and causes the average Nusselt number to behave non-monotonically, reaching an optimum value at a specific slug length. This non-monotonic trend has been explained by analyzing the hydrodynamics of the system. The effect of the inter-block distance generally showed a monotonic increasing trend for the average Nusselt number, except for a single slug length. This behavior has been explained by the vorticity and Fourier transform analysis. An alternating slug injection configuration has also been analyzed. The analysis of this configuration reveals a non-monotonic behavior of the average Nusselt number vs the number of injected slugs. This non-monotonic behavior shows that for each value of the selected slug length, there is a critical number of slugs, and consequently, a critical slug length for which the average Nusselt number reaches a maximum. The hydrodynamics of the system justifies this non-monotonic behavior. Finally, the friction factor and performance evaluation criterion are presented as a guideline for the design of the microchannels based on flow configuration.