bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagations of Sin-Gaussian Beam with Astigmatism through Oceanic Turbulence
Authors: Zhu Kaicheng , Gao Chang , Li Jiahui , Ren Dengjuan , Zhu Jie
Published: August 2021

The propagation behaviours of a sin-Gaussian beam (SiGB) with astigmatism in oceanic water is analysed. The analytical expressions for the average intensity of such a beam are derived by using the extended Huygens-Fresnel integral. Its average intensity and on-axial intensity distributions in oceanic water are numerically examined. Then, we mainly focus on the effect of the beam parameters and the medium structure constant on the propagation behaviours for the astigmatic SiGBs in oceanic water, revealing that the evolutions of the intensity distributions can be effectively modulated by adjusting the astigmatic parameter, coherence length and the atmosphere turbulence strength.
Ophthalmologische Notfälle
Authors: Kupferschmid Sebastian
Published: August 2021

In der notfallmedizinischen Ausbildung sind die okulären Notfälle nur ein kleines Kapitel.
Der Grund dafür ist das Fehlen einer vitalen Bedrohung und die begrenzten Möglichkeiten in der
präklinischen Versorgung. Für den Patienten jedoch, steht eine Beteiligung der Augen in einer
Notfallsituation oft im Vordergrund. Selbst bei schwersten Organverletzungen kann eine
Augenbeteiligung die die gesamte Aufmerksamkeit des Patienten allein auf dieses Sinnesorgan
richten. Die prähospitale Versorgung hat einen erheblichen Einfluss auf die Prognose bei
okulären Notfällen. Daher sollte der Notfallmediziner in der Lage sein, ophthalmologische
Notfälle zu klassifizieren und zu behandeln. Das Ziel ist es, eine adäquate prähospitale
Versorgung zu gewährleisten und den psychischen Leidensdruck des Patienten durch medizinische
Souveränität bei Notfällen mit Beteiligung des Auges zu reduzieren.
Ng. – eine frühe Diskussion über die Zuverlässigkeit von Symptomen
Authors: Zauner Bernhard
Published: August 2021

In der frühen homöopathischen Literatur ist das Kürzel „Ng.“ nicht zu übersehen, deshalb ist vielen Homöopathen dieses bekannter als der Name, der dahintersteckt, nämlich Cajetan Nenning (1769–1845): Botaniker, Wundarzt, Militärarzt, Stiftsarzt und ein nicht unumstrittener Homöopath in der Frühzeit der Homöopathie.
Angsterleben von Hausärzten, Psychiatern und Chirurgen zu Beginn der COVID-19-Pandemie in Deutschland
Authors: Bohlken Jens , Pabst Alexander , Schömig Friedericke , Pumberger Matthias , Lempert Thomas , Michalowsky Bernhard , Riedel-Heller Steffi
Published: August 2021

Ziel Die COVID-19-Pandemie stellt eine besondere Belastung für die Ärzteschaft dar. Wir untersuchten Unterschiede und Bedingungsfaktoren im pandemiebezogenen Angsterleben von Hausärzten (HA), Psychiatern (PS) und Chirurgen (CH) in Deutschland.

Methode Schriftliche Befragung (April–Mai 2020) von 608 Ärzten (HA n = 162, PS n = 299, CH n = 147).

Ergebnisse Ein hohes Angstniveau im Zusammenhang mit COVID-19 berichteten 31,1 % der HA, 19,2 % der PS und 11,6 % der CH. CH berichteten am häufigsten Kontakt mit COVID-19-Patienten (68,5 %), gefolgt von HA (51,0 %) und PS (8,1 %). Das Belastungserleben war bei HA insgesamt am größten. CH fühlten sich hingegen am besten informiert und schätzten ihre Resilienz am höchsten ein. Innerhalb der Fachdisziplinen war ein hohes Maß erlebter Angst in Bezug auf COVID-19 positiv mit dem Grad der wahrgenommenen Infektionsgefahr assoziiert.

Schlussfolgerung Studien zur Belastung von Ärzten verschiedener Fachgruppen geben wichtige Hinweise zur Optimierung des Pandemiemanagements.
Ethnoveterinary Remedies Used in Avian Complementary Medicine in Selected Communal Areas in Zimbabwe
Authors: Jambwa Prosper , Katsande Simbarashe , Matope Gift , McGaw Lyndy J.
Published: August 2021

Plant remedies used in avian ethnomedicine are potential candidates for the development of phytogenic feed additives. An ethnoveterinary survey was carried out in 3 districts in Zimbabwe to document plants used in poultry ethnomedicine and identify plants that have the potential to be used for the development of poultry phytogenic feed additives. The survey employed questionnaire-guided oral interviews with 146 smallholder farmers. Key areas of investigation and discussion were poultry production and traditional knowledge in bird health care (ethnotreatments and poultry disease control). The survey documented a total of 36 plant species cited as being useful interventions for the treatment and management of various poultry ailments/health constraints. These medicinal plants belonged to 22 families, with the Fabaceae family the dominant family. The plant species were used to treat 11 disease/health constraint categories, with the highest number of species being used for
coccidiosis. Trees (44.44%) were the main reservoir of medicinal plants followed by herbs (36.11%), shrubs (8.33%), climbers (8.33%), and flowers (2.78%). Based on the results of the survey, Bobgunnia madagascariensis, Aloe chabaudii, Adenia gummifera, Erythrina abyssinica, Agave sisalana, Capsicum frutescens, Strychnos cocculoides, Aloe greatheadii, Tridactyle bicaudata, Senna singueana, Sarcostemma viminale, Morus alba, and Moringa oleifera are potential candidates for the development of phytogenic feed additives.
Ambulante psychotherapeutische Versorgung von Kindern und Jugendlichen in Deutschland: Status quo und Trends im Zeitraum 2009–2018
Authors: Jaite Charlotte , Hoffmann Falk , Seidel Anja , Mattejat Fritz , Bachmann Christian
Published: August 2021

Ziel der Studie Bestimmung der Prävalenz ambulanter Psychotherapie (PT) bei gesetzlich versicherten Kindern/Jugendlichen in Deutschland.

Methodik Aus KV-Daten der Jahre 2009–2018 wurde die PT-Prävalenz bei 0- bis 19-Jährigen berechnet und nach Geschlecht, Alter und Bundesland stratifiziert, es wurden Berufsgruppe der PT-Erbringer, codierte psychiatrische Diagnosen sowie PT-Verfahren betrachtet.

Ergebnisse Im Jahr 2018 erhielten 7,3 % (5,9 % [Hessen] bis 8,8 % [Niedersachsen]) PT-Leistungen (2009: 7,1 %). Hiervon waren 18,4 % (2009: 12,8 %) Richtlinien-PT (ab 2012: Verhaltenstherapie [VT] häufigstes Verfahren). 15- bis 19-Jährige erhielten am häufigsten PT, es fanden sich nur mäßige Geschlechtsunterschiede. Häufigste Leistungserbringer waren Ärzte für Kinder- und Jugendpsychiatrie, häufigste Diagnosen Angst-/emotionale Störungen, ADHS und Anpassungsstörungen.

Schlussfolgerungen Die PT-Prävalenz hat sich im untersuchten Zeitraum kaum verändert. Jedoch ist der Anteil von Richtlinien-PT angestiegen, mit VT als führendem Verfahren.
New Guaianolide Sesquiterpene Lactones and Other Constituents from Pyrethrum pulchrum
Authors: Erdenetsogt Uugangerel , Nadmid Suvd , Paetz Christian , Dahse Hans-Martin , Voigt Kerstin , Gotov Choijamts , Boland Wilhelm , Dagvadorj Enkhmaa
Published: August 2021

Pyrethrum pulchrum is a rare Mongolian plant species that has been traditionally used as an ingredient in various remedies. Bioactivity-guided fractionation performed on the methanol extract of its aerial parts led to the isolation of 2 previously undescribed guaianolide-type sesquiterpene lactones, namely 1β,10β-epoxy-8α-hydroxyguaia-3,11(13)-dien-6,12-olide (1) and 1,8,10-trihydroxyguaia-3,11(13)-dien-6,12-olide (2), along with the isolation or chromatographic identification of 11 compounds, arglabin (3), 3β-hydroxycostunolide (4), isocostic acid (5), (E)-9-(2-thienyl)-6-nonen-8-yn-3-ol (6), (Z)-9-(2-thienyl)-6-nonen-8-yn-3-ol (7), N
1,N
5,N
10,N
14-tetra-p-coumaroyl spermine (8), chlorogenic acid (9), 3,5-di-O-caffeoylquinic acid (10), 3,5-di-O-caffeoylquinic acid methyl
ester (11), 3,4-di-O-caffeoylquinic acid (12), and tryptophan (13). Their structures were assigned based on spectroscopic and spectrometric data. The antimicrobial, antiproliferative and cytotoxic activities of selected compounds were evaluated. The new compounds showed weak to moderate antimicrobial activity. Arglabin (3), the major sesquiterpene lactone found in the methanol extract of P. pulchrum, exhibited the highest activity against human cancer lines, while compound 1 also possesses significant antiproliferative activity against leukemia cells.
An Efficient Protocol for the Synthesis of Pyrazolo[1,5-c]quinazolines by a Staudinger–Aza-Wittig–Dehydroaromatization Sequence
Authors: Ren Zhilin , He Ping , Xu Mingxian , Chen An , Qiu Jiying , Zu Mingming , Zhang Yi , Wang Jiayi
Published: August 2021

The one-pot synthesis of azide-substituted dihydropyrazoles in isopropanol was performed by using chalcones, hydrazine hydrate, and an acyl chloride at 0 ℃. Subsequent Staudinger–aza-Wittig–dehydroaromatization reactions of the products with methyl(diphenyl)phosphine were also investigated for further application in the construction of pyrazolo[1,5-c]quinazolines.
Nickel Boride Catalyzed Reductions of Nitro Compounds and Azides: Nanocellulose-Supported Catalysts in Tandem Reactions
Authors: Dinér Peter , Proietti Giampiero , Prathap Kaniraj Jeya , Ye Xinchen , Olsson Richard T.
Published: August 2021

Nickel boride catalyst prepared in situ from NiCl2 and sodium borohydride allowed, in the presence of an aqueous solution of TEMPO-oxidized nanocellulose (0.01 wt%), the reduction of a wide range of nitroarenes and aliphatic nitro compounds. Here we describe how the modified nanocellulose has a stabilizing effect on the catalyst that enables low loading of the nickel salt pre-catalyst. Ni-B prepared in situ from a methanolic solution was also used to develop a greener and facile reduction of organic azides, offering a substantially lowered catalyst loading with respect to reported methods in the literature. Both aromatic and aliphatic azides were reduced, and the protocol is compatible with a one-pot Boc-protection of the obtained amine yielding the corresponding carbamates. Finally, bacterial crystalline nanocellulose was chosen as a support for the Ni-B catalyst to allow an easy recovery step of the catalyst and its recyclability for new reduction cycles.
Physician Perceptions on Quality of Life and Resuscitation Preferences for Extremely Early Newborns
Authors: LoRe Danielle , Mattson Christopher , Feltman Dalia M. , Fry Jessica T. , Brennan Kathleen G. , Arnolds Marin
Published: August 2021

Objective The study aimed to explore physician views on whether extremely early newborns will have an acceptable quality of life (QOL), and if these views are associated with physician resuscitation preferences.

Study Design We performed a cross-sectional survey of neonatologists and maternal fetal medicine (MFM) attendings, fellows, and residents at four U.S. medical centers exploring physician views on future QOL of extremely early newborns and physician resuscitation preferences. Mixed-effects logistic regression models examined association of perceived QOL and resuscitation preferences when adjusting for specialty, level of training, gender, and experience with ex-premature infants.

Results A total of 254 of 544 (47%) physicians were responded. A minority of physicians had interacted with surviving extremely early newborns when they were ≥3 years old (23% of physicians in pediatrics/neonatology and 6% in obstetrics/MFM). The majority of physicians did not believe an extremely early newborn would have an acceptable QOL at the earliest gestational ages (11% at 22 and 23% at 23 weeks). The majority of physicians (73%) believed that having an extremely preterm infant would have negative effects on the family's QOL. Mixed-effects logistic regression models (odds ratio [OR], 95% confidence interval [CI]) revealed that physicians who believed infants would have an acceptable QOL were less likely to offer comfort care only at 22 (OR: 0.19, 95% CI: 0.05–0.65, p < 0.01) and 23 weeks (OR: 0.24, 95% CI: 0.07–0.78, p < 0.02). They were also more likely to offer active treatment only at 24 weeks (OR: 9.66, 95% CI: 2.56–38.87, p < 0.01) and 25 weeks (OR: 19.51, 95% CI: 3.33–126.72, p < 0.01).

Conclusion Physician views of extremely early newborns' future QOL correlated with self-reported resuscitation preferences. Residents and obstetric physicians reported more pessimistic views on QOL.

Key Points
Safety and Outcomes in Infants Born to Mothers Participating in Retosiban Treatment Trials: ARIOS Follow-up Study
Authors: Powell Marcy , Pimenta Jeanne M. , Beach Kathleen J. , Snidow Jerry , Saade George R. , Thornton Steve , Haque Nazneen , Miller Diane , Correa Erika Ochoa , Scott Rhona
Published: August 2021

Objective Retosiban, an oxytocin receptor antagonist, was developed for treating spontaneous preterm labor (sPTL) in women with intact membranes. This ARIOS follow-up study aimed to characterize clinical safety, morbidity, and mortality of infants exposed to retosiban or comparator over 2 years.

Study Design ARIOS prospectively assessed outcomes in infants whose mothers received at least one dose of retosiban or comparator (placebo/atosiban) in two Phase 3 sPTL trials. Both trials were terminated prematurely owing to poor enrolment. Infants could be enrolled into ARIOS from 28 days after estimated due date until hospital discharge or up to 9 months (corrected age). An internally developed questionnaire detailing medical conditions, mortality and resource use (Child Health Inventory; CHI), Ages and Stages Questionnaire-3 (ASQ-3), Modified Checklist for Autism in Toddlers–Revised with Follow-Up, and Child Behavior Checklist for Ages 1.5 to 5 were completed remotely by parents or legal guardians at prespecified intervals. Serious adverse events (SAEs) were primarily captured via CHI. No comparative statistical analysis was conducted between treatment arms.

Results A total of 49 (86%) infants who had received retosiban and 49 (78%) infants who had received a comparator were enrolled in ARIOS. No deaths occurred during the study. Nine infants experienced SAEs: 6/49 (12.2%) infants in the comparators group and 3/49 (6.1%) in the retosiban group. Of the nine SAEs, seven were due to infections, three, and four in the retosiban and comparators groups, respectively. Based on ASQ-3 score, the incidence of neurodevelopmental delay at 18 and 24 months were 0/18 (0%) and 2/25 (8%) with retosiban and 7/22 (31.8%) and 3/21 (14.3%) with comparator, respectively.

Conclusion The current study showed no unexpected adverse outcome or impairment with retosiban based on safety monitoring and neurodevelopment assessments. No further follow-up is intended owing to the discontinuation of clinical development of retosiban.

Key Points
Inverse Regulation of Confluence-Dependent ADAMTS13 and von Willebrand Factor Expression in Human Endothelial Cells
Authors: Popa Miruna , Hecker Markus , Wagner Andreas H.
Published: August 2021

ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) is a zinc-containing metalloprotease also known as von Willebrand factor (vWF)-cleaving protease. Low ADAMTS13 plasma levels are associated with an increased risk of arterial thrombosis, including myocardial infarction and cerebrovascular disease. The expression and regulation of this metalloprotease in human endothelial cells have not been systematically investigated. In this study, we demonstrate that ADAMTS13 expression is inhibited by proinflammatory cytokines tumor necrosis factor-α and interferon-γ as well as by CD40 ligand, which was hitherto unknown. Factors protecting against atherosclerosis such as exposure to continuous unidirectional shear stress, interleukin-10, or different HMG-CoA reductase inhibitors like, e.g., simvastatin, atorvastatin, or rosuvastatin, did not influence ADAMTS13 expression. Unidirectional periodic orbital shear stress, mimicking oscillatory flow conditions found at atherosclerosis-prone arterial bifurcations, had also no effect. In contrast, a reciprocal correlation between ADAMTS13 and vWF expression in endothelial cells depending on the differentiation state was noted. ADAMTS13 abundance significantly rose on both the mRNA and intracellular protein level and also tethered to the endothelial glycocalyx with the degree of confluency while vWF protein levels were highest in proliferating cells but significantly decreased upon reaching confluence. This finding could explain the anti-inflammatory and antithrombotic phenotype of dormant endothelial cells mediated by contact inhibition.
Colonoscopic Instillation of Coca-Cola for Evacuation of Large Fecaloma: A Report of Two Cases and Review of Literature
Authors: Seth Avnish Kumar , Gupta Mahesh Kumar , Bansal Rinkesh Kumar , Verma Radha Krishan , Kaur Gursimran
Published: August 2021

Introduction Fecaloma is a large mass of organized hardened feces causing impaction, usually in rectum and sigmoid colon. Medical management usually entails digital evacuation, use of clearance enema, and oral laxatives. We report two patients managed successfully with colonoscopic instillation of Coca-Cola and review the literature.

Case Report Patient 1: A 37-year-old male presented with firm, nontender, pitting mass over lower abdomen for 2 months and inability to pass stool for 1 month. Per-rectal examination and imaging confirmed presence of solid stool with gross distension of rectum and sigmoid colon. Attempts at clearance of stool with conventional methods were unsuccessful. At colonoscopy, 4 L of Coca-Cola was instilled into descending and sigmoid colon, leading to evacuation of 10 L of fragmented and liquid stool.

Patient 2: A 72-year-old diabetic lady presented with constipation and tender, firm pelvic mass extending till mid-abdomen for 6 months. Per-rectal examination revealed presence of hard stool. Imaging confirmed large amount of fecal matter in dilated rectum, sigmoid, and descending colon. Attempts at evacuating stool with digital evacuation, sodium phosphate enema, and oral polyethylene glycol were unsuccessful. At colonoscopy, two sittings of instillation of 990 mL of Coca-Cola Light each were done into sigmoid colon over 2 days, resulting in clearance.

Conclusion Colonoscopic instillation of Coca-Cola may be effective in evacuation of large fecaloma from rectum, sigmoid, and descending colon when refractory to use of conventional methods like digital disimpaction, rectal enema, and oral laxatives.
Comparative study of charged particle dynamics in time-stationary and time-varying spatially chaotic magnetic fields with sinusoidal spatiotemporal dependence
Authors: Samanta Subha
Published: August 2021

The first step in understanding charged particle dynamics is based on the development of relevant three-dimensional models for the fields and using a test particle approach in the presence of prescribed electromagnetic fields. In this paper, first, we investigate the dynamics of charged particles in spatially inhomogeneous time-stationary Beltrami magnetic fields. The field lines of stationary three-dimensional Beltrami magnetic fields are chaotic. Characterization of dynamical behavior of charged particles moving in such fields is provided through Lyapunov exponents and the exponent associated with the transport law. The main motive of this study is to relate the spatial properties of magnetic field lines over the entire space to the chaotic behavior and transport properties of charged particles. Later, the same idea is applied to the charged particles in the presence of time-periodic Beltrami magnetic fields, and it is found that unlike the previous case with time-stationary magnetic fields, here, a clear understanding of anomalous diffusion cannot be achieved from the knowledge of particle dynamics through Lyapunov exponents.
Experimental investigation of an active slat for airfoil load alleviation
Authors: Singh P. , Neuhaus L. , Huxdorf O. , Riemenschneider J. , Wild J. , Peinke J. , Hölling M.
Published: August 2021

This article discusses the utilization of an active slat concept to reduce turbulence induced fluctuating loads on an airfoil. The performance of the active slat is tested in the wind tunnel under different complex inflows created by an active grid resulting in variations in the angle of attack. Different open loop control strategies are developed to mitigate the load fluctuations on the airfoil. The aerodynamics around the airfoil is changed by actively moving the trailing edge of the slat. It is observed that the active slat concept is able to alleviate load fluctuations on the airfoil for inflow angle fluctuations of different scales.
Comparison of hexagonal boron nitride and MgO tunnel barriers in Fe,Co magnetic tunnel junctions
Authors: Lu H. , Robertson J. , Naganuma H.
Published: August 2021

Magnetic tunnel junctions (MTJ) with MgO/Fe based interfaces and out-of-plane spin direction form the basis of present-day spin-transfer-torque magnetic random-access memory (STT-MRAM) devices. They are a leading type of nonvolatile memory due to their very long endurance times and lack of reliability problems. Many semiconductor devices, such as the field effect transistor or nonvolatile memories, have undergone fundamental changes in materials design as dimensional scaling has progressed. Here, we consider how the future scaling of the MTJ dimensions might affect materials choices and compare the performance of different tunnel barriers, such as 2D materials like h-BN with the existing MgO tunnel barriers. We first summarize key features of MgO-based designs of STT-MRAM. We then describe general aspects of the deposition of 2D materials and h-BN on metals. We compare the band structures of MgO and h-BN with their band gaps corrected for the GGA band error. The different absorption sites of h-BN on Fe or Co are compared in terms of physisorbtive or chemisorbtive bonding sites and how this affects their spin-polarized bands and the transmission magneto-resistance (TMR). The transmission magneto-resistance is found to be highest for the physisorptive sites. We look at how these changes would affect the overall TMR and how scaling might progress.
Stress-controlled n–p conductivity switch based on intercalated ZrTe2
Authors: Morozova Natalia V. , Korobeynikov Igor V. , Shkvarina Elena G. , Titov Alexey A. , Titov Alexander N. , Ovsyannikov Sergey V.
Published: August 2021

The ability to manipulate the electronic transport properties and electronic states in transition metal chalcogenides greatly expands the range of their application. Here, we investigate the effect of applied stress on the electrical conductivity of quasi-two-dimensional ZrTe2 and several intercalated AgxZrTe2 and CuxZrTe2 crystals using pressure-dependent measurements of their Seebeck coefficients (thermoelectric powers) at room temperature. The pristine ZrTe2 crystal is characterized by p-type semimetal conductivity, and the pressure dependence of its thermopower exhibits a broad wave-like maximum at about 2 GPa. Potentially, this feature is related to a charge density wave transition. The electrical conductivity in all the intercalated crystals is of n-type, but an applied pressure of about 1.5–3 GPa, dependent on crystal composition, reversibly inverts it to p-type. At pressures above 6 GPa, thermopower curves for all samples demonstrate a nearly identical and degenerate pressure behavior, thereby suggesting metallization of the samples. We verify the reproducibility of the above features by multiple pressure cycling of the samples up to 9 GPa. We, therefore, experimentally show that slightly intercalated ZrTe2 crystals with n-type conductivity can be utilized as stress-controlled n-/p-switches of the conductivity type. We give and discuss simple examples of how the above n–p conductivity inversions could be potentially implemented in various modules for next-generation nanoelectronic devices.
Versatile microparticle propulsion system by light-guided dielectrophoresis: Proposed method and theoretical calculation
Authors: Liang Zexi , Fan Donglei (Emma)
Published: August 2021

Developing materials for active matter that can efficiently respond to external stimuli with designed multifold mechanical motions remains a major challenge, and overcoming this will greatly propel the advancement of micromachines and microrobots toward unprecedented biomedical, electronic, and particle-separation applications. Here, we propose an innovative working mechanism that allows multifold-translational-motion control of semiconductor microentities by AC dielectrophoresis with simple visible-light stimulation. We study the dielectrophoresis forces on semiconducting particles of various geometries in aqueous suspension by modeling with the consideration of both the Maxwell–Wagner relaxation and the electrical-double-layer-charging effect. With the obtained understanding, we rationally design a manipulation system that can versatilely transport semiconductors and orient them toward desired directions simultaneously by tuning the light intensity in an electric field. This research could provide insights toward developing a new class of micromachines with rarely found control flexibility and precision and offer a new route toward separation and purification of optoelectric microparticles of different geometries.
Neutron-induced point defects and luminescence properties of enriched Zn82Se crystals
Authors: Silva B. C. , Cury L. A. , Leal A. S. , Menezes M. A. B. C. , Nagorny S. , Nisi St. , Saiki M. , Jacimovic R. , Krambrock K.
Published: August 2021

Enriched Zn82Se is a very promising material for the detection of the neutrionoless double beta decay. The 82Se isotope acts as the source of the decay, and ZnSe detects the scintillation and bolometric events. Due to the high cost in the preparation of the Zn82Se material, the optimization of its properties, especially those related to the scintillation process, is mandatory. It is well known that excellent scintillation efficiency in ZnSe is obtained when the material presents close donor–acceptor pairs, as, for example, the A-centers. In this work, neutron irradiation was used to study formation of point defects in enriched and non-enriched ZnSe samples. Applying instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectroscopy, the enrichment of Zn82Se samples was determined to ∼95%, in addition, trace impurities such as Cu, I, and Na were quantified by INAA at the μg/g level. Based on electron paramagnetic resonance (EPR) and photo-EPR measurements, we show that irradiation with fast neutrons induced point defects such as the isolated zinc vacancy (VZn) and a new low-symmetric donor center called NC1, which we tentatively assign to Zn di-interstitials. Low-temperature photoluminescence measurements of the neutron-irradiated Zn82Se revealed three broad PL bands centered in the visible spectral range. Based on the INAA analysis shown in this work, we attribute the previously unidentified 540 nm PL band in the Zn82Se sample to recombination between shallow donors and deep copper acceptors. The formation of point defects by neutron irradiation and their stability are discussed.
Generating optical supercontinuum and frequency comb in tenuous plasmas
Authors: Qu Kenan , Fisch Nathaniel J.
Published: August 2021

There are several mechanisms by which the frequency spectrum of a laser broadens when it propagates at near-relativistic intensity in a tenuous plasma. Focusing on one-dimensional effects, we identify two strong optical nonlinearities, namely, four-wave mixing (FWM) and forward Raman scattering (FRS), for creating octave-wide spectra. FWM dominates the interaction when the laser pulse is short and intense, and its combination with phase modulation produces a symmetrically broadened supercontinuum. FRS dominates when the laser pulse is long and relatively weak, and it broadens the laser spectrum mainly toward lower frequencies and produces a frequency comb. The frequency chirping combined with group velocity dispersion compresses the laser pulse, causing higher peak intensity.
Correlative analysis of embedded silicon interface passivation by Kelvin probe force microscopy and corona oxide characterization of semiconductor
Authors: Aubriet Valentin , Courouble Kristell , Gros-Jean Mickael , Borowik Łukasz
Published: August 2021

We report a correlative analysis between corona oxide characterization of semiconductor (COCOS) and Kelvin probe force microscopy (KPFM) in a study of embedded silicon surfaces in the field of chemical and field-effect passivation. The COCOS approach gives access to the defect density, the total charge contained in the passivation stack, and the potential barrier. Based on the COCOS parameters, we could probe by KPFM to analyze the influence of the passivation stack upon the surface photovoltage. Thus, KPFM emerges as a valuable method to access chemical and field-effect passivation directly. We confirm that it is possible to differentiate by KPFM the influence of local band bending (i.e., field-effect passivation) from the effects due to the local recombination rates (i.e., chemical passivation). The measurements were carried on five different passivation layers of different thicknesses, precisely, 10.5 nm SiO2, 50 nm SiN, 7 nm Al2O3, 7 nm HfO2, and a double layer of 7 nm Al2O3 below 53 nm Ta2O5. Based on our correlative analysis, we could identify by KPFM that HfO2 displays the best chemical passivation properties. Additionally, we confirm that using an anti-reflective coating such as a Ta2O5 layer on top of Al2O3 causes the chemical passivation to deteriorate. Finally, for p-type silicon, SiN appears to be the worst case in terms of field-effect passivation.
Causality indices for bivariate time series data: A comparative review of performance
Authors: Edinburgh Tom , Eglen Stephen J. , Ercole Ari
Published: August 2021

Inferring nonlinear and asymmetric causal relationships between multivariate longitudinal data is a challenging task with wide-ranging application areas including clinical medicine, mathematical biology, economics, and environmental research. A number of methods for inferring causal relationships within complex dynamic and stochastic systems have been proposed, but there is not a unified consistent definition of causality in the context of time series data. We evaluate the performance of ten prominent causality indices for bivariate time series across four simulated model systems that have different coupling schemes and characteristics. Pairwise correlations between different methods, averaged across all simulations, show that there is generally strong agreement between methods, with minimum, median, and maximum Pearson correlations between any pair (excluding two similarity indices) of 0.298, 0.719, and 0.955, respectively. In further experiments, we show that these methods are not always invariant to real-world relevant transformations (data availability, standardization and scaling, rounding errors, missing data, and noisy data). We recommend transfer entropy and nonlinear Granger causality as particularly strong approaches for estimating bivariate causal relationships in real-world applications. Both successfully identify causal relationships and a lack thereof across multiple simulations, while remaining robust to rounding errors, at least 20% missing data and small variance Gaussian noise. Finally, we provide flexible open-access Python code for computation of these methods and for the model simulations.
Machine learning methods for probabilistic locked-mode predictors in tokamak plasmas
Authors: Akçay Cihan , Finn John M. , Brennan Dylan P. , Burr Thomas , Kürkçüoğlu Doğa M.
Published: August 2021

A rotating tokamak plasma can interact resonantly with the external helical magnetic perturbations, also known as error fields. This can lead to locking and then to disruptions. We leverage machine learning (ML) methods to predict the locking events. We use a coupled third-order nonlinear ordinary differential equation model to represent the interaction of the magnetic perturbation and the plasma rotation with the error field. This model is sufficient to describe qualitatively the locking and unlocking bifurcations. We explore using ML algorithms with the simulation data and experimental data, focusing on the methods that can be used with sparse datasets. These methods lead to the possibility of the avoidance of locking in real-time operations. We describe the operational space in terms of two control parameters: the magnitude of the error field and the rotation frequency associated with the momentum source that maintains the plasma rotation. The outcomes are quantified by order parameters that completely characterize the state, whether locked or unlocked. We use unsupervised ML methods to classify locked/unlocked states and note the usefulness of a certain normalization of the order parameters. Three supervised ML classifiers are used in suite to estimate the probability of locking in the region of control parameter space with hysteresis, i.e., the set of control parameters for which both locked and unlocked states can exist. The results show that a neural network gives the best estimate of the locking probability. An analogy of the present locking model with the van der Waals equation of state is also provided.
Setup for pressurizing thin films through the superconductor–insulator transition
Authors: Cohen R. , Nikolaevsky M. , Salem R. , Frydman A.
Published: August 2021

We describe an experimental setup designed for transport measurement of thin disordered superconducting films as a function of pressure up to several GPa. We use a specially designed single screw diamond anvil cell that allows the gradual increase of high pressure at cryogenic temperatures. By depositing amorphous films of disordered superconducting indium oxide directly on the diamond, we avoid the effect of pressure-induced structural changes in the substrate. Using this technique, we are able to drive thin films through a pressure tuned superconductor–insulator transition.
A new method for detecting heteromorphic workpiece brazing layer quality based on thermal probe
Authors: Hu Chaoxu , Feng Shiwei , Zhang Yamin , He Xin , Bai Kun , Wang Sheng , Pan Shijie
Published: August 2021

Traditional brazing quality inspection methods find it difficult to detect brazing layer defects on heteromorphic workpieces. Thus, a non-destructive testing technology based on a thermal probe is developed in this work. Scanning thermal resistance testing and analysis are carried out for two types of workpiece samples with different structures, and an evaluation calculation method is proposed to effectively characterize the brazing effect of the workpiece. By comparison with standard workpieces, qualified brazing layer products can be selected. In addition, the feasibility of this method is verified by ANSYS thermal simulations. In comparison with the x ray, it also has shown the superiority of this method. Experimental results show that this method can effectively evaluate the brazing layer quality of workpieces with heteromorphic and complex structures, and the reliability of the workpiece is further improved.
Liquid-jet instability at high pressures with real-fluid interface thermodynamics
Authors: Poblador-Ibanez Jordi , Sirignano William A.
Published: August 2021

The injection of liquid fuel at supercritical pressures is a relevant topic in combustion but is usually overlooked. In the past, the wrong assumption whereby the liquid phase undergoes a fast transition to a supercritical state was made, thus neglecting any role of two-phase interface dynamics in the early stages of the atomization process. However, recent studies have shown that local thermodynamic phase equilibrium and mixing between the involved species allow the coexistence of both phases in this pressure range. In this work, a volume-of-fluid method adapted to variable-density real fluids is used to solve the low-Mach-number governing equations coupled with a thermodynamic model based on the Soave–Redlich–Kwong equation of state. The mixing process, interface thermodynamics, and early deformation of a cool liquid jet composed of n-decane surrounded by a hotter gas composed of oxygen at 150 bar are analyzed. Although heat conducts from the hotter gas into the liquid, net condensation can provide the proper local energy balance at high pressures. Then, vaporization and condensation may happen simultaneously at different interface locations. As pressure increases, liquid and gas mixtures become more alike in the vicinity of the interface. Thus, a combination of low surface tension force and gas-like liquid viscosities causes an early growth of surface instabilities. Early results indicate some similarity with high-Weber-number incompressible flows. The role of vortex dynamics on the interface deformation is analyzed by using the λρ dynamical vortex identification method.
Magnetic properties of NbSi2N4, VSi2N4, and VSi2P4 monolayers
Authors: Akanda Md. Rakibul Karim , Lake Roger K.
Published: August 2021

The recent demonstration of MoSi2N4 and its exceptional stability to air, water, acid, and heat has generated intense interest in this family of two-dimensional materials. Among these materials, monolayers of NbSi2N4, VSi2N4, and VSi2P4 are semiconducting, easy-plane ferromagnets with negligible in-plane magnetic anisotropy. They, thus, satisfy a necessary condition for exhibiting a dissipationless spin superfluid mode. The Curie temperatures of monolayer VSi2P4 and VSi2N4 are determined to be above room temperature based on Monte Carlo and density functional theory calculations. The magnetic moments of VSi2N4 can be switched from in-plane to out-of-plane by applying tensile biaxial strain or electron doping.
Numerical investigation on the control of cryogenic fluid oscillations by applying an external sound source
Authors: Hu Lulu , Yang Peng , Liu Yingwen
Published: August 2021

Self-excited oscillations that occur in the cryogenic helium tube system are seen as thermoacoustic instabilities. To increase the operation stability of the system and suppress the conversion of thermal energy into acoustic waves, one solution where an external sound source driven by a piston is applied to control oscillations in a helium tube system. In this work, a numerical study of minimizing self-excited oscillations is conducted. Oscillation frequency and amplitude of the coupling system of the helium tube system and the external sound source are acquired as functions of the piston speed and frequency. It is found that the suppression of pressure oscillations can be achieved when the driving frequency is far from the self-excited oscillation frequency of the cryogenic helium tube. Increasing the driving speed of the piston gives rise to the coupling oscillation amplitude, and the control strategy leads to 99.2% oscillation amplitude reduction. Moreover, the nonlinear dynamics behavior caused by the coupling of self-excited oscillations and the external sound source is revealed. Synchronization of frequency occurs when the system is coupled to the external sound source oscillating with different frequencies. Our findings could provide a guideline in minimizing self-excited oscillations in the cryogenic helium system.
Theoretical analysis of the condensation of combustion products in thin gaseous layers
Authors: Yanez Jorge , Veiga-López Fernando
Published: August 2021

In this paper, a theoretical analysis of the condensation of combustion products in narrow gaps between planar plates is performed. The investigation is motivated by the empirical results shown by Veiga-López [“Flame propagation in narrow channels,” Ph.D. thesis (Carlos III University of Madrid, 2020)] and the lack of a theoretical description directly applicable to them. In these experiments, he describes how discontinuous condensed water films appeared on the walls of the combustion chamber, forming dry/wet stripes parallel to the flame front at the products region. The formulation developed here is derived from a general approach for condensation, which is simplified considering the conditions of high-temperature combustion products. Notably, the liquid phase disappears from the system of equations, which exclusively contains the gaseous phase. The expressions resulting are analytical, simple, and easy to interpret. They allow us to understand qualitatively the effects of the main physical phenomena of the process, which is described by the interaction between heat exchange, mass transfer, the thermodynamic conditions, and the velocity of the combustion products. The construct is subsequently utilized to perform the numerical parametric studies, to analyze the influence of two main parameters of the problem: gap thickness and flame velocity. Despite the relative simplicity of the model, it predicts similar condensation–vaporization–condensation cycles to those observed at the laboratory.
Simulation and experimental study on droplet breakup modes and redrawing of their phase diagram
Authors: Chang Jiaqing , Jiang Fan , Liu Ziteng , Zhu Dachang , Shen Teng
Published: August 2021

Dimensionless numbers are often used to characterize the various modes of droplet breakup processes. However, the current methods of calculating these dimensionless numbers are not uniform—consequently, the calculation results are different, resulting in different phase diagrams of droplet separation. This paper first summarizes the methods of calculating the Weber number. The maximum transient velocity at the center of a nozzle is then used as the characteristic velocity for calculating the Weber number, and this formulation is used to solve certain scenarios in which the traditional Weber number cannot be applied, such as the strange phenomenon of the upward flight of separated droplets. A mathematical model is established to simulate the various separation forms of droplets, and the experimental study is also carried out. This upward flight of droplets is found to be the result of competition between the liquid inertial force, surface tension force, and suction effect of the nozzle mouth. The final velocity of the droplets depends on the existence of a stagnation surface and the corresponding sweep effect. Finally, the phase diagram of different droplet separation modes is drawn in the Ohnesorge–Weber number space.
Interstitially strengthened metastable FeCoCr-based medium-entropy alloys with both high strength and large ductility
Authors: Cao Boxuan , Wang Cheng , Yang Tao , Liu Chain Tsuan
Published: August 2021

We investigated the effect of interstitial solutes on the phase stability and tensile properties of metastable FeCoCr-based medium-entropy alloys (MEAs). Thermodynamic calculations indicate that the interstitial carbon atom acts as an austenite stabilizer and suppresses the thermally induced martensite formation. With the benefit from interstitial strengthening, carbon-doped FeCoCr-based MEAs have demonstrated an enhanced tensile strength as compared with the undoped counterpart. Originated from the phase metastability and low stacking-fault energy, the martensitic transformation can be activated upon the plastic deformation, leading to the dynamic microstructural refinement. In this way, the significantly improved strength with a maintained tensile ductility can be achieved in the developed MEAs. Our findings have demonstrated that the incorporation of interstitial solutes into metastable alloys contributes to the development of high-performance alloys with a superior strength-ductility synergy.
State of charge and state of health estimation based on dual nonlinear adaptive observer and hysteresis model of lithium-ion battery
Authors: Ma Yan , Zhu Jiajun , Li Xin , Tang Zhiguo
Published: August 2021

Accurate estimation of state of health (SOH) and state of charge (SOC) can provide a basis for regular operation and fault diagnosis of batteries, which is of great significance for electric vehicles. In this paper, a dual nonlinear adaptive observer (DNLAO) is presented to realize the joint estimation of SOC and SOH. Considering that the battery hysteresis characteristics impact the estimation, an equivalent circuit model including the hysteresis characteristic is established, and the model equations with uncertainties are analyzed. In designing observers, the Takagi–Sugeno fuzzy model is introduced to reduce the model complexity, and adaptive parameters are added to connect the observed output with measured output to reduce the model uncertainty and improve estimation accuracy. The proposed observer convergence is proved based on the Lyapunov equation. The simulation results show that the SOC estimation error and the SOH estimation error by DNLAO are lower than those of a dual extended Kalman filter. DNLAO has high estimation accuracy and fast convergence speed on SOC and SOH joint estimation, and can achieve long-term SOH estimation.
Planar narrow bandpass filter based on Si resonant metasurface
Authors: Zheng Ze , Komar Andrei , Zangeneh Kamali Khosro , Noble John , Whichello Lachlan , Miroshnichenko Andrey E. , Rahmani Mohsen , Neshev Dragomir N. , Xu Lei
Published: August 2021

Optically resonant dielectric metasurfaces offer unique capability to fully control the wavefront, polarization, intensity, or spectral content of light based on the excitation and interference of different electric and magnetic Mie multipolar resonances. Recent advances of the wide accessibility in nanofabrication and nanotechnologies have led to a surge in the research field of high-quality functional optical metasurfaces, which can potentially replace or even outperform conventional optical components with ultra-thin features. Replacing conventional optical filtering components with metasurface technology offers remarkable advantages, including lower integration cost, ultra-thin compact configuration, easy combination with multiple functions, and less restriction on materials. Here, we propose and experimentally demonstrate a planar narrow bandpass filter based on the optical dielectric metasurface composed of Si nanoresonators in arrays. A broadband transmission spectral valley (around 200 nm) has been realized by combining electric and magnetic dipole resonances adjacent to each other. Meanwhile, we obtain a narrow-band transmission peak by exciting a high-quality leaky mode, which is formed by partially breaking a bound state in the continuum generated by the collective longitudinal magnetic dipole resonances in the metasurface. Owing to the in-plane inversion symmetry of our nanostructure, the radiation of this antisymmetric mode is inhibited at far field, manifesting itself a sharp Fano-shape peak in the spectrum. Our proposed metasurface-based filter shows a stable performance for oblique light incidence with small angles (within 10°). Our work implies many potential applications of nanoscale photonics devices, such as displays, spectroscopy, etc.
Effect of rheology and interfacial tension on spreading of emulsion drops impacting a solid surface
Authors: Piskunov M. , Semyonova A. , Khomutov N. , Ashikhmin A. , Yanovsky V.
Published: August 2021

This paper presents an experimental and theoretical study of Newtonian and non-Newtonian (Bingham plastic) emulsion drop impact on a solid non-heated surface. The utilization of different emulsifiers at a constant concentration of continuous and dispersed phases in emulsions allows the considerable variation of the surface tension at the liquid–liquid interface. Our data for the maximum spreading diameter of water, n-decane, and emulsion drops impacting on a surface are compared with that predicted from the existing models for single-phase liquid drops. All selected models underpredict the experimental data. As a result, the importance of considering the capillary effects at the internal interfaces of the emulsion drops and the careful examination of all rheological properties in the case of Bingham plastic fluids is confirmed experimentally and is taken into account theoretically. The models of Pasandideh-Fard et al. [“Capillary effects during droplet impact on a solid surface,” Phys. Fluids 8, 650 (1996)] and Ukiwe and Kwok [“On the maximum spreading diameter of impacting droplets on well-prepared solid surfaces,” Langmuir 21, 666–673 (2005)] are modified and adapted to the emulsion drop by means of including the additional surface energy term at the liquid–liquid interface of the emulsion drop in the energy conservation equation and the non-Newtonian Reynolds number. The predictions of the maximum spreading diameter give good agreement with the measured one. Several constraints and future lines of research that relate to a specific behavior of the compound liquid drops at the impact on a solid surface are highlighted.