bluuebunny/crossref_metadata_2025 huggingface dataset:
Suplementación efectiva de vitamina D en pacientes con fractura tibial
Authors: Drago Sebastián , Rojas Jose Miguel , Jiménez Horacio , Gaggero Nicolás , Olivieri Rodrigo , Innocenti Piero , Barrientos Víctor , Jara Aquiles
Published: July 2022

Objetivos Determinar la prevalencia de déficit de vitamina D, así como evaluar la seguridad y efectividad de un nuevo método de carga con colecalciferol en pacientes adultos con fractura de tibia.

Materiales y Métodos Se reclutaron a 56 pacientes consecutivos con edades entre 18 y 65 años con fractura de tibia ingresados en nuestro hospital durante 1 año. Se determinó el nivel de 25-hidroxivitamina D ([25(OH)-D]) al ingreso y tras suplementación con 100.000 UI semanales de colecalciferol, durante 3 o 5 semanas, en casos de insuficiencia ([25(OH)-D] entre 20 ng/mL y 29,9 ng/mL) o deficiencia ([25(OH)-D] < 20 ng/mL), respectivamente. Se determinó la prevalencia de hipovitaminosis D, el porcentaje de normalización de [25(OH)-D], y los efectos adversos.

Resultados Se evaluaron 56 pacientes; 98,2% presentó hipovitaminosis D, y 28 (73,7%) y 10 (26,3%) presentaron déficit e insuficiencia, respectivamente. Tras la suplementación, 92,1% alcanzaron niveles [25(OH)-D] normales. Ningún paciente presentó efectos adversos.

Discusión La prevalencia de deficiencia de vitamina D en nuestra población fue mayor a la reportada en la literatura. Comprobamos que un esquema de suplementación en altas dosis de vitamina D es seguro, y más efectivo que los previamente recomendados. Este esquema de suplementación puede ser implementado en futuros estudios randomizados.

Conclusión La prevalencia de hipovitaminosis D en pacientes adultos chilenos con fractura de tibia fue alta (98,2%). El esquema de suplementación con vitamina D propuesto fue efectivo y seguro.

Nivel de Evidencia Estudio terapéutico. Nivel 2.
Oxygen Saturation Profiles in Healthy Term Infants in Early Postnatal Life
Authors: Goetz Elizabeth M. , Tomlin Brandon D. , Rinaldo Kathryn E. , Baumann-Blackmore Nicole L. , Petro Rachel L. , Smith Beth B. , Zapata Jasmine Y. , Lasarev Michael R. , McBride Elizabeth B. , Kaluarachchi Dinushan C.
Published: July 2022

Objective Oxygen saturation profiles generated by pulse oximetry are used as a clinical tool in the neonatal intensive care unit (NICU). There is limited evidence on normal oxygen saturation profile values in term infants. This study aimed to determine oxygen saturation profiles over an 8-hour monitoring period among healthy term neonates between 24 and 48 hours after birth.

Study Design A prospective cohort study of healthy term neonates born at 37 to 41 weeks of gestation. Preductal oxygen saturations were continuously monitored for an 8-hour period between 24 and 48 hours of life using pulse oximetry. Oxygen profile histograms were recorded for analysis. The average percent oxygen saturation (SpO2) was measured over the entire study duration for each neonate and was characterized as the fraction of time of their SpO2 reading was in each of five intervals: ≤80, 81 to 84, 85 to 89, 90 to 94, and 95 to 100%.

Results Seventy-five neonates were included in the study. Median SpO2 was 95.4%. Percentage time spent in each of the five SpO2 intervals was as follows: 0.07 (≤80), 0.15 (81–84), 0.88 (85–89), 26.9 (90–94), and 67.3% (95–100%). Eighteen infants (24%) spent the highest percentage of time in SpO2 of 90 to 94%.

Conclusion This study provides reference ranges for oxygen profiles in healthy term neonates during 24 to 48 hours of life. Nearly one-quarter of newborns spent the highest percentage of time in SpO2 of 90 to 94%. This data is important when interpreting oxygen saturation profiles of term neonates admitted to the NICU.

Key Points
Implementation and Outcomes of a Model of Care for Placenta Accreta Spectrum in a Community-Based Private Practice
Authors: Wagner William , Loichinger Matthew , Sidebottom Abbey C. , Wunderlich Whitney L. , Vacquier Marc , Jentink Theresa , Aguilera Marijo N. , Ahanya Sureshbabu N. , Morgan Elizabeth , Parker Meiling , Wothe Donald D.
Published: July 2022

Objective The aim of the study is to describe a model of care and outcomes for placenta accreta spectrum (PAS) implemented in the context of a community based non-academic health system.

Study Design The program for management of PAS includes a multidisciplinary team approach with protocols for ultrasound assessment, diagnosis, and surgery. The program was implemented in the two largest private hospitals in the Twin Cities, Minnesota, United States. Maternal and fetal outcomes as well as cost were compared for histopathologic confirmed PAS cases before (2007–2014, n = 41) and after (2015–2017, n = 26) implementation of the PAS program.

Results Implementation of the PAS program was associated with ICU admission reductions from 53.7 to 19.2%, p = 0.005; a decrease of 1,682 mL in mean estimated blood loss (EBL) (p = 0.061); a decrease in transfusion from 85.4 to 53.9% (p = 0.005). The PAS program also resulted in a (non-significant) decrease in both surgical complications from 48.8 to 38.5% (p = 0.408) and postoperative complications from 61.0 to 42.3% (p = 0.135). The total cost of care for PAS cases in the 3 years after implementation of the program decreased by 33%.

Conclusion The implementation of a model of care for PAS led by a perinatology practice at a large regional non-academic referral center resulted in reductions of ICU admissions, operating time, transfusion, selected surgical complications, overall postoperative complications, and cost.

Key Points
Neuromyelitis Optica Spectrum Disorders in Black African: Experience of Togo (2015–2020)
Authors: Apetse Kossivi , Kouassi Komlan , Anayo Nyinèvi Komla , Waklatsi Kokouvi Panabalo , Guinhouya Mensah Kokou , Agba Léhleng , Kumako Vinyo Kodzo , Kombate Damelan , Assogba Komi , Belo Mofou , Balogou Agnon Koffi
Published: July 2022

Introduction Neuromyelitis optica spectrum disorders (NMOSD) would disproportionately affect blacks within mixed populations. However, they are rarely reported in black African. The objective of this work was to report the experience of Togo, a West African country in terms of NMOSD.

Methods This is a series of six cases diagnosed between 2015 and 2020 in the only three neurology departments in Togo. The diagnosis of NMOSD was made according to the criteria of the International Panel for NMO Diagnosis (2015) and the patients had a minimum clinical follow-up of 6 months after the diagnosis. The search for anti-aquaporin 4 (AQP4) antibodies was performed by immunofluorescence on transfected cells.

Results The mean age was 25.33 years and the sex ratio female/male was 5/1. The average time between the first attack and the diagnosis was 122.83 days. Clinically, there was isolated medullary involvement (2/6), simultaneous opticomedullary involvement (3/6), and area postrema syndrome (1/6). Five patients were anti-AQP4 positive. All six patients had extensive longitudinal myelitis. At 6 months of follow-up, there was one case of death and one case of blindness.

Conclusion The rarity of NMOSD cases in Togo could be linked to an underestimation. To better characterize the NMOSDs of the black African population, multicenter and multidisciplinary studies are necessary.
Thoracic Fluid Content in Neonates Presented with Respiratory Distress as a Predictive Tool for Transient Tachypnea of Newborn
Authors: Bassiouny Mohamed R. , Abdelhady Shimaa E. , Sobh Ali
Published: July 2022

Introduction Respiratory conditions are the most common reason for admission of newborns to a neonatal care unit. The index of contractility (ICON) can be used to measure the thoracic fluid content (TFC) in neonates which is a significant parameter in cases presented with transient tachypnea of newborn (TTN).

Objective The objective was to compare TFC between newborn infants with TTN compared with other causes of respiratory distress (RD). We tested the hypothesis that TFC would be higher in infants with TTN.

Study Design In total, 105 newborns were enrolled at the delivery room and were categorized into three groups: TTN, other causes of RD, and control, according to physical examination and Chest X-Ray. TFC was measured within the first 6 hours for all infants and at 24 and 48 hours for the first two groups.

Results Demographic data showed higher male participants and use of antenatal steroid therapy in RD groups. TFC within the first 6 hours was higher in RD groups. However, TFC at 24 hours of ≤24 mL/kg, and TFC drop rate at 24 hours of >12% are statistically significant discriminators of TTN from non-TTN, with sensitivity and specificity of 97.1 and 47.1%, and 60 and 82.4%, respectively (Fig 1 and 2).

Conclusion ICON can be used in conjunction with clinical parameters and CXR as a tool for differentiation between TTN and other causes of RD within the first 24 hours of life by using the cutoff value of TFC at 24 hours and TFC drop rate. This will allow earlier and optimum management of different causes of RD.

Key Points
Clinical Utility of Bioelectrical Impedance Analysis Parameters for Evaluating Patients with Lower Limb Lymphedema after Lymphovenous Anastomosis
Authors: Son Woo Chul , Kwon Jin Geun , Hong Joon Pio , Park Chang Sik , Kim Sang Ah , Do Jung Hwa , Cheon Hwayeong , Gelvosa Ma Nessa , Suh Hyun Suk , Jeon Jae Yong
Published: July 2022

Background In lymphedema, lymphatic fluid accumulates in the interstitial space, and localized swelling appears. Lymphovenous anastomosis (LVA) is the most widely used surgery to rebuild a damaged lymphatic system; however, assessing outcome of LVA involves performing volume measurements, which provides limited information on body composition changes. Therefore, we analyzed the bioelectrical impedance analysis (BIA) parameters that can reflect the status of lymphedema patients who underwent LVA.

Methods We retrospectively reviewed records of 42 patients with unilateral lower extremity lymphedema who had LVA. We measured the perioperative BIA parameters such as extracellular water (ECW) ratio and volume as defined by the percentage of excess volume (PEV). We evaluated the relationship between the amount of change in PEV and in BIA parameters before and after surgery. We confirmed the correlation between ΔPEV and BIA parameters using Spearman's correlation.

Results Most patients included had secondary lymphedema due to cancer. Average age was 51.76 years and average body mass index was 23.27. PEV and all BIA parameters after surgery showed a significant difference (p < 0.01) compared with preoperative measurements. The ECW ratio aff/unaff showed the strongest correlation with PEV with a correlation coefficient of 0.473 (p < 0.01).

Conclusion Our findings suggest that BIA parameters, especially ECW ratio aff/unaff could reflect the status of patients with lower limb lymphedema after LVA. Appropriate use of BIA parameters may be useful in the postoperative surveillance of patients.
Impacto dos parâmetros espinopélvicos pré-operatórios na correção de lordose segmentar após fusão intersomática lombar por via lateral de um nível
Authors: Arnoni Daniel , Amaral Rodrigo , Pokorny Gabriel H. , Moriguchi Rafael , Pimenta Luiz
Published: July 2022

Objetivos O presente estudo teve como objetivo avaliar se os parâmetros espinopélvicos pré-operatórios podem influenciar o ganho da lordose segmental após fusão intersomática lombar por via lateral de um nível.

Métodos Os seguintes parâmetros radiológicos foram medidos nos raios X: incidência pélvica, lordose lombar, versão pélvica, lordose L4S1, lordose segmental do nível operado, índice intraoperatório de lordose segmentar, mismatch pélvico (IP-LL), proporção de lordose distal, delta de lordose segmentar, PT > 20, inclinação sacral real e inclinação sacral ideal, e a correlação dessas variáveis com o ganho da lordose segmentar foi investigada. Posteriormente, foi realizada uma análise exploratória de cluster para identificar características comuns entre os pacientes e o ganho de lordose segmentar.

Resultados O presente estudo contou com 144 pacientes, dos quais 76% apresentaram ganho de lordose segmentar. Os parâmetros mais correlacionados com o ganho de lordose segmentar foram lordose segmentar pré-operatória (−0,50) e delta intraoperatório de lordose (0,51). Além disso, os pacientes dos grupos de incidência pélvica (IP) alto tiveram tendência de ganho de lordose segmental maior (p < 0,05) e redução do risco de perda de lordose segmental (chances 6.08).

Conclusão Pacientes com perfis de IP médios baixos apresentaram maiores chances de perda de lordose segmentar. No entanto, os parâmetros espinopélvicos pré-operatórios por si só não parecem desempenhar um papel significativo no destino do ganho da lordose segmentar.
Pedicled Flaps versus Free Flaps for Oral Cavity Cancer Reconstruction: A Comparison of Complications, Hospital Costs, and Functional Outcomes
Authors: Sittitrai Pichit , Ruenmarkkaew Donyarat , Klibngern Hanpon
Published: July 2022

Introduction Free flaps have been the preferred method for reconstruction after resection of oral cavity cancer. However, pedicled flaps remain valuable alternatives in appropriate settings.

Objective The main objective of the present study was to compare surgical complications, hospital costs, and functional outcomes of oral cavity cancer patients who underwent soft tissue reconstruction with pedicled flaps or free flaps.

Methods A total of 171 patients were included in the study. Ninety-eight underwent reconstruction with a pectoralis major, submental, temporalis, or supraclavicular pedicled flap, and in 73 patients, a radial forearm or anterolateral thigh free flap had been used. The cases were retrospectively reviewed, and a comparative analysis was carried out between the two groups.

Results Recipient site and flap complications, speech, and swallowing functions did not differ between groups, but donor site complications, operative time, hospital stay, and costs were significantly reduced in the pedicled flap group compared with the free flap group. However, the pectoralis major flap reconstruction resulted in a more inferior swallowing function than the free flap reconstruction.

Conclusions With comparable complications and functional outcomes, while decreasing in costs, pedicled flaps are a useful alternative to free flaps in oral cavity cancer reconstruction. However, in an extensive defect (> 70 cm2), free flaps are the reconstruction of choice for the preservation of swallowing function.
Arthroscopic Needling Technique for the Treatment of Wrist Ganglia
Authors: Kaempf O Ricardo , Gómez Gustavo , Brunelli João P. F. , Aita Marcio A. , Carratalà Vicente , Delgado S Pedro J.
Published: July 2022

Background Synovial cysts (SCs) are the most frequent wrist tumors; the arthroscopic treatment presents good results when surgery is indicated for symptomatic or patients with cosmetic concerns. The tumoral lesion should be arthroscopically decompressed or drained toward the inside of the joint through pedicle opening and resection of a small portion of the capsule. Hence, the cyst pedicle must be found for the success of this technique.

Description of Technique Some tricks have already been described to facilitate SC location during arthroscopy. We describe an indirect technique that employs an 18-G needle to enhance SC pedicle location and drainage. The technique involves a puncture on the interval of the carpal extrinsic ligaments where the pedicle is suspected to be remain. When found, cyst is drained with a single-puncture motion of the need which promotes cyst content extravasation due to pressure toward the joint.

Patients and Methods This method has been employed in 16 patients, including 9 with dorsal cysts, and seven with volar cysts.

Results All patients presented complete recovery and symptom improvement in up to 30 days, with total disappearance of the cyst. There were no relapses or severe complications within the 12-month follow-up.

Conclusion This is a safe, useful technique that facilitates location of intra-articular cyst pedicle, thus avoiding unnecessary damage in healthy tissues with no increased costs.
Avaliação do posicionamento dos parafusos na cirurgia de Latarjet: Existe correlação entre paralelismo à glenoide e complicações radiográficas?*
Authors: Kawakami Eduardo Felipe Kin Ito , Godoy Gabriel Paris de , Cohen Marcio T. , Yamada Andre Fukunishi , Motta Filho Geraldo R. , Ejnisman Benno , Belangero Paulo Santoro
Published: July 2022

Objetivo Avaliar se o paralelismo dos parafusos com a glenoide na cirurgia de Latarjet interfere no posicionamento do enxerto e verificar a reprodutibilidade de um método de mensuração da posição dos parafusos.

Métodos Estudo retrospectivo, multicêntrico, de pacientes com instabilidade anterior do ombro submetidos à cirurgia de Latarjet modificada e no mínimo 1 ano de seguimento pós-operatório. Dois médicos radiologistas analisaram as imagens tomográficas pós-operatórias, adquiridas em um banco de dados, para avaliação do posicionamento dos parafusos e das complicações radiográficas.

Resultados Foram avaliados 34 pacientes, com idades entre 21 e 60 anos, sendo que um deles tinha acometimento bilateral dos ombros, totalizando 35 ombros avaliados. A avaliação tomográfica dos ângulos de inclinação dos parafusos não apresentou diferença entre os observadores. Houve concordância intra e interobservador para avaliação dos seguintes parâmetros cirúrgicos: posição do enxerto, presença ou não de complicações radiográficas.

Conclusão A técnica descrita para mensuração do paralelismo dos parafusos na cirurgia de Latarjet apresentou uma concordância intra e inter observador muito boa e excelente, respectivamente. O paralelismo do parafuso com a glenoide é recomendado; no entanto, não é condição obrigatória e única para se evitar as complicações radiográficas.
Herbal and Dietary Supplement Use among Adult Patients Undergoing Treatment at a Tertiary Hospital Cancer Center
Authors: Enriquez Kevin P. D. A. , Esplana Christian C.
Published: July 2022

The use of herbal and dietary supplement in cancer patients has been increasing over the past years, while the risk of its adverse effects and undesirable reactions with conventional treatment has also been accumulating. Limited studies involving perception of herbal and dietary supplements (HDS) by cancer patients have been conducted in our setting. An initial survey was conducted among adult cancer patients undergoing treatment at the Zamboanga City Medical Center (ZCMC) Cancer Institute. HDS users were recruited for focus group discussion (FGD) via purposive sampling. A total of four groups were conducted. Clinical and demographic data were presented through descriptive statistics while data from the FGD were subjected to coding and thematic analysis. Among 22 respondents, more than half (65.4%) of the participants were noted to have used HDS and most (54.5%) were breast cancer patients with stage-II and -III disease. Treatment of cancer, coping with chemotherapy, and relief of symptoms were the major reasons for use. Majority (36.36%) were influenced by the media/internet and most (50%) did not disclose information to their physician. Eight respondents, whose income were below minimum wage, spent more than 25% of their income on HDS, with some having spent more than 50%. This may seriously limit funds and result in failure to adhere to treatment. Among cancer patients in ZCMC, HDS use is widely practiced and half of them do not disclose this information to their physicians. The expenditure on HDS consumes 25 to 50% of the population's meager monthly income. The secrecy surrounding its use and attendant cost may possibly limit adherence and adversely affect outcomes.
Treatment of Primary Dorsal Wrist Ganglion—A Systematic Review
Authors: Horvath Alexandra , Zsidai Bálint , Konaporshi Shanga , Svantesson Eleonor , Hamrin Senorski Eric , Samuelsson Kristian , Zeba Nenad
Published: July 2022

Purpose The aim of this study was to compare the rates of recurrence and wound infection in patients with primary dorsal wrist ganglion treated with aspiration (with or without an injection of an additive), open excision, or arthroscopic resection.

Methods This systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and registered on PROSPERO. Systematic electronic searches in PubMed (MEDLINE), EMBASE, Web of Science, and the Cochrane Library of Controlled Trials were performed on May 5, 2020, and June 1, 2021, respectively. All clinical studies written in English determining the recurrence and wound infection rates after treatment of primary dorsal wrist ganglion with aspiration, open excision, or arthroscopic resection in patients over the age of 16 years were eligible for inclusion. Quality assessment was guided by the Cochrane Collaboration's tool for randomized controlled trials (RCTs) and the methodological index for nonrandomized studies (MINORS) tool for observational studies.

Results The literature searches resulted in 1,691 studies. After screening, five RCTs, enrolling 233 patients, and six observational studies, enrolling 316 patients with primary dorsal wrist ganglions were included. Quality assessment of the included RCTs and observational studies determined the existing level of evidence pertaining to primary dorsal wrist ganglion treatment to be low. About 11 studies reported on recurrence rate, which ranged between 7 and 72% for patients initially treated with aspiration (with or without an injection of an additive). In comparison, the recurrence rate for the open excision and arthroscopic resection groups ranged between 6 to 41% and 0 to 16%, respectively. Four studies investigated wound-related complications, for which zero infections were reported, irrespective of treatment.

Conclusion The evidence summarized in this systematic review demonstrates a considerable variability in recurrence rate following aspiration and open or arthroscopic resection of a primary dorsal wrist ganglion. The greatest variability in recurrence was displayed among studies on aspiration. The overall infection rate after treatment of dorsal wrist ganglions seems to be low regardless of the treatment type. However, the divergent results of individual studies highlight a pressing need for prospective controlled trials assessing outcomes following dorsal wrist ganglion treatment.

Level of Evidence Systematic review on level 1 to 4 clinical therapeutic studies.
Wave breaking phenomenon for the generalized FORQ equation
Authors: Zhu Mingxuan , Li Zhenda
Published: July 2022

In this paper, we consider the generalized Fokas–Olver–Rosenau–Qiao equation (also called the ab-family of equation). The local well-posedness and blow-up scenario are investigated. Sufficient conditions on the initial data to guarantee wave breaking are established for b = 2. For b = 2 and 1/6 < a ≤ 1/3, we also show that if the initial momentum density is positive in a compact support and the length of the support is small enough, then wave breaking occurs.
Development of a high dynamic range retarding potential analyzer for electric propulsion plume diagnosis
Authors: Maystrenko D. , Shagayda A. , Kravchenko D. , Lovtsov A.
Published: July 2022

A new high dynamic range retarding potential analyzer design is proposed to measure the ion energy distribution in electric propulsion plasma plumes. The main difference between the proposed probe and previous designs is an ion-optical system with a high negative accelerating potential. Applying the principle of acceleration and focusing of the ion flow provides the correct operation of the probe in a dense plasma in which the Debye length can be ten times smaller than the diameter of the grid apertures. As a result, the new probe has high transparency with an extended operating range of measured plasma densities. Another advantage of the probe is its accurately known and time-stable transparency for ions, so the probe can measure the absolute values of the ion current density like the Faraday probe. The analyzer geometry, which provides measurement in the range of ion current densities up to 100 A/m2 at ion energies up to 2000 eV with an error of no more than 2%, was determined using numerical simulation. We present the measurement results of the plasma plume of a Hall effect thruster with a nominal discharge power of 2.3 kW.
Manifold learning and segmentation for ultrasonic inspection of defects in polymer composites
Authors: Liu Kaixin , Yu Qing , Lou Weiyao , Sfarra Stefano , Liu Yi , Yang Jianguo , Yao Yuan
Published: July 2022

Non-destructive ultrasonic testing is beneficial for monitoring the structural health of polymer composites. However, owing to scattering and other factors, ultrasonic data often appear as noisy signals or images containing artifacts. The analysis of ultrasound signals highly depends on the expertise of trained human inspectors. Hence, the development of ultrasonic data analysis methods, particularly unsupervised methods, is necessitated. In this study, a novel unsupervised method is developed for the ultrasonic inspection of defects in polymer composites, named manifold learning and segmentation. In a uniform manifold approximation and projection model, nonlinear dimensionality reduction is first performed on high-dimensional ultrasound data for extracting and visualizing defect features. Subsequently, semantic segmentation is performed to predict/discriminate between defects and backgrounds. Consequently, subsurface defects in the composites can be effectively detected. Experimental results and comparisons on two carbon fiber reinforced polymer specimens demonstrate the effectiveness of the proposed method.
Crystal structure deformation and phase transition of AlScN thin films in whole Sc concentration range
Authors: Satoh Shiro , Ohtaka Koichi , Shimatsu Takehito , Tanaka Shuji
Published: July 2022

This article reports lattice deformation and phase transition of AlScN thin films in the whole composition. AlScN films were deposited on Pt/Ta/SiO2/Si substrates by direct current magnetron reactive sputtering with Al and Sc targets. At Sc concentration up to 30%, AlScN has a wurtzite structure with piezoelectricity. Transition from a wurtzite phase to a two-phase mixture happens between 30% and 35% Sc concentration, and transition from a two-phase mixture to a cubic phase happens between 38% and 43% Sc concentration. The wurtzite structure gradually deforms with the decrease in lattice constant c from 16% to 35% Sc concentration. Lattice constant c at 38% Sc in the two-phase mixture region is larger than that of 35% Sc concentration. These increases mean that distortion of c axis for the wurtzite structure over 35% Sc concentration in the two-phase mixture region is considered to be released and/or eased due to the appearance of the cubic phase, and that Sc concentration of the wurtzite phase to be smaller and that of the cubic phase larger than the film composition measured by energy-dispersive x-ray spectroscopy and Rutherford backscattering spectroscopy. At higher Sc concentration up to 43%, the remained wurtzite phases are replaced by non-piezoelectric cubic phases, and the cubic structure approaches the rock-salt structure of ScN with a further increase in Sc concentration.
The Schottky emission effect: A critical examination of a century-old model
Authors: Wu Ernest Y. , Li Baozhen
Published: July 2022

Using a quantum mechanical calculation, we investigate the fundamental limitations of the Schottky emission (SE) model for its applications to electron injection into dielectrics from a metal or semiconductor electrode. This work covers a wide range of electric fields from 0.01 to 10 MV/cm and a large temperature span with many barrier height values (ΦB). We conclude that the SE model is only applicable for a very small class of dielectrics under 0.1 MV/cm and at high temperatures over ∼330 K. For many defective dielectrics with large barrier heights (ΦB ≥ ∼1.5 eV) in back-of-line/middle-of-line/metal–insulator–metal capacitor applications, the corresponding electric fields for the measurable currents far exceed 0.1 MV/cm, and up to 10 MV/cm, the application of the SE model is likely invalid so that the extracted ΦB values may not be correct. We provide a quantitative guide to avoid future misapplications of the SE model.
Modeling and analysis of reluctance motion system with asymmetrical air gaps
Authors: Pumphrey Michael , Alatawneh Natheer , Al Janaideh Mohammad
Published: July 2022

To achieve high throughput and efficiency, semiconductor photolithography machines need an actuation system that can meet high acceleration and precision demands on the nanoscale. One available solution is the reluctance actuator, which provides higher acceleration and force output than the standard Lorentz actuator. A floating stage with air-bearings is used to eliminate friction in the photolithography process; however, vibration transfer is not entirely eliminated, leading to potential misalignment and asymmetries between the actuator elements. With asymmetrical offsets between mover elements, the output force can be greatly affected. This paper shows a method for estimating the force of various asymmetrical cases for the C-core reluctance actuator. Analytical models are developed and further improved through polynomial curve fitting using precomputed finite element simulation results from Comsol Multiphysics (COMSOL) to achieve more optimal solutions. An experiment verified the results of the force estimation equations, which were within ∼11% for different cases of asymmetric air gaps. This contribution will lead to a design for a control system that will overcome the issue of asymmetries or other altered states.
EXPANSE: A time-of-flight EXPanded Angle Neutron Spin Echo spectrometer at the Second Target Station of the Spallation Neutron Source
Authors: Do Changwoo , Ashkar Rana , Boone Cristina , Chen Wei-Ren , Ehlers Georg , Falus Peter , Faraone Antonio , Gardner Jason S. , Graves Van , Huegle Thomas , Katsumata Reika , Kent Darian , Lin Jiao Y. Y. , McHargue Bill , Olsen Bradley , Wang Yangyang , Wilson Danielle , Z Y
Published: July 2022

EXPANSE, an EXPanded Angle Neutron Spin Echo instrument, has been proposed and selected as one of the first suite of instruments to be built at the Second Target Station of the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is designed to address scientific problems that involve high-energy resolution (neV–μeV) of dynamic processes in a wide range of materials. The wide-angle detector banks of EXPANSE provide coverage of nearly two orders of magnitude in scattering wavenumbers, and the wide wavelength band affords approximately four orders of magnitude in Fourier times. This instrument will offer unique capabilities that are not available in the currently existing neutron scattering instruments in the United States. Specifically, EXPANSE will enable direct measurements of slow dynamics in the time domain over wide Q-ranges simultaneously and will also enable time-resolved spectroscopic studies. The instrument is expected to contribute to a diverse range of science areas, including soft matter, polymers, biological materials, liquids and glasses, energy materials, unconventional magnets, and quantum materials.
GeSe/MoTe2 vdW heterostructure for UV–VIS–NIR photodetector with fast response
Authors: Chen Ping , Pi Lejing , Li Zexin , Wang Haoyun , Xu Xiang , Li Dongyan , Zhou Xing , Zhai Tianyou
Published: July 2022

GeSe is a layered p-type semiconductor with intriguing optoelectrical properties such as high absorption coefficient, high carrier mobility, and narrow bandgap, which promises a broadband photoresponse over a wide spectral range. However, GeSe based broadband photodetectors could not achieve both high responsivity and fast response speed. Therefore, it is urgent to improve the properties of GeSe based broadband photodetectors. Herein, a GeSe/MoTe2 van der Waals (vdW) heterostructure was designed. The GeSe/MoTe2 vdW heterostructure possesses broadband photodetection over ultraviolet, visible, and near infrared. The device has competitive responsivity (R) and detectivity (D*) over a broadband even at 1050 nm, which are 28.4 A/W and 5.6 × 109 Jones, respectively. Excitingly, the response speed for 365 nm is as fast as 3 μs, which is much faster than most other GeSe devices. Overall, our results suggest that the GeSe/MoTe2 heterostructure can provide an effective strategy to achieve broadband photodetectors with both high responsivity and fast response.
Boundary conditions for molecular simulations of isolated elastic defects. Case study: The ⟨111⟩ screw dislocation in bcc W
Authors: Savvidi Camilla , Evangelakis Georges , Pontikis Vassilis
Published: July 2022

A new set of boundary conditions is proposed for molecular simulations of isolated elastic defects such as dislocations and cracks. The case study of the ⟨111⟩ screw dislocation in body centered cubic (bcc) tungsten, modeled via a phenomenological, n-body cohesion functional, serves validating the new boundary conditions by computing structural properties of this defect and comparing these with results from the literature. Lowest energy configurations of the dislocated crystal have been obtained by molecular statics incorporating the new boundary conditions. The associated displacement and energy landscapes reveal conformal to the predictions of the elastic theory for a screw dislocation embedded in an infinitely extended crystal. In particular, no energy gradients and positional mismatch of atoms are found at the terminations of the computational box, validating thereby the new boundary conditions. Furthermore, it is shown that the structure, the spatial extension, and the excess energy of the two possible core polarizations of this dislocation compare consistently with existing findings for this and other bcc metals. Close to the dislocation line, energy minimization triggers the emergence of anelastic edge displacements extending over distances unexpectedly much larger than the dislocation core radius. Therefore, the conclusion is reached that in molecular simulations, the transverse to the dislocation line dimensions of the atomistic model should be taken considerably larger than it is accustomed. Perspectives opened by the present work are briefly discussed.
Crucial role of S8-rings in structural, relaxation, vibrational, and electronic properties of liquid sulfur close to the λ transition
Authors: Flores-Ruiz H. , Micoulaut M.
Published: July 2022

Liquid sulfur has been studied by density-functional based molecular dynamics simulations at different temperatures ranging from 400 up to 700 K across the well-documented λ transition. Structure models containing either a majority of Sn chains or S8 rings are considered and compared to experimental data from x-ray scattering. The comparison suggests a liquid structure of a majority of twofold sulfur at low temperature, dominated by S8 rings that open progressively upon temperature increase. Typical features associated with such rings are analyzed and indicate that they contribute to a specific third correlating distance in the pair correlation function and to a contribution at low wavevector k in the reciprocal space. The vibrational properties of liquid sulfur are also considered and indicate a contribution at 60 meV that is associated with both chains and rings, albeit the latter lead to a more intense peak at this wavenumber. The underlying network structure also impacts the dynamic properties of the melts which display enhanced dynamic heterogeneities when S8 rings are present. The analysis of the electronic Kohn–Sham energies shows insulating character with a gap of about ≃2.0 eV, albeit the presence of localized mid-gap states is acknowledged that can be associated, in part, with the presence of S6 rings.
Improving the electrostatic design of the Jefferson Lab 300 kV DC photogun
Authors: Wijethunga S. A. K. , Mamun M. A. , Suleiman R. , Hernandez-Garcia C. , Bullard B. , Delayen J. R. , Grames J. , Krafft G. A. , Palacios-Serrano G. , Poelker M.
Published: July 2022

The 300 kV DC high voltage photogun at Jefferson Lab was redesigned to deliver electron beams with a much higher bunch charge and improved beam properties. The original design provided only a modest longitudinal electric field (Ez) at the photocathode, which limited the achievable extracted bunch charge. To reach the bunch charge goal of approximately few nC with 75 ps full-width at half-maximum Gaussian laser pulse width, the existing DC high voltage photogun electrodes and anode–cathode gap were modified to increase Ez at the photocathode. In addition, the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the non-symmetric nature of the inverted insulator photogun design. We present the electrostatic design of the original photogun and the modified photogun and beam dynamics simulations that predict vastly improved performance. We also quantify the impact of the photocathode recess on beam quality, where recess describes the actual location of the photocathode inside the photogun cathode electrode relative to the intended location. A photocathode unintentionally recessed/misplaced by sub-millimeter distance can significantly impact the downstream beam size.
Rayleigh–Taylor and Richtmyer–Meshkov instabilities in the presence of an inclined magnetic field
Authors: Sun Y. B. , Gou J. N. , Zeng R. H.
Published: July 2022

A unified and analytical model is developed to study the effects of an inclined magnetic field on magneto-Rayleigh–Taylor (MRT) and magneto-Richtmyer–Meshkov (MRM) instabilities in ideal magnetohydrodynamics. Unlike either a horizontal or a vertical magnetic field is present, the decay modes possess decaying and oscillation behaviors together. The vorticity transportation is analyzed. The dispersion relations are derived, and some interesting phenomena are observed. For a small R that represents the ratio of the magnetic field strength, or equivalently, the inclination θ, the growth rate of MRT instabilities resembles the case when a vertical magnetic field is present. For a large R, the growth rate resembles to the case when a horizontal magnetic field exists. The maximum growth rate becomes strongly dependent on At instead of on R. Furthermore, analytical expression is obtained for the MRM instability by using the impulsive accelerated model. The decaying and oscillating rates of the perturbed amplitude are explicitly related to θ. For two limiting cases, with either the vertical or the horizontal magnetic field existing, our results retrieve previous one of the theoretical analyses and numerical simulations. Generally, the asymptotic amplitude becomes independent of the wave number of the initial perturbation in the MRM instability. These findings regarding magneto-hydrodynamic interfacial instabilities in an inclined magnetic field could provide physical insights for magnetically driven targets and astrophysical observations. This analytical model is easily expanded to investigate the effects of finite thickness of magnetic slab and sheared magnetic field in relevant to high-energy-density physics and to astrophysics.
Photodissociation of quinoline cation: Mapping the potential energy surface
Authors: Ramanathan Karthick , S. Arun , Bouwman Jordy , Avaldi Lorenzo , Vinitha M. V. , Bolognesi Paola , Richter Robert , Kadhane Umesh R.
Published: July 2022

A detailed exploration of the potential energy surface of quinoline cation (C9H7N·+) is carried out to extend the present understanding of its fragmentation mechanisms. Density functional theory calculations have been performed to explore new fragmentation schemes, giving special attention to previously unexplored pathways, such as isomerization and elimination of HNC. The isomerization mechanisms producing five- to seven-membered ring intermediates are described and are found to be a dominant channel both energetically and kinetically. Energetically competing pathways are established for the astrochemically important HNC-loss channel, which has hitherto never been considered in the context of the loss of a 27 amu fragment from the parent ions. Elimination of acetylene was also studied in great detail. Overall, the computational results are found to complement the experimental observations from the concurrently conducted PEPICO investigation. These could potentially open the doors for rich and interesting vacuum ultraviolet radiation-driven chemistry on planetary atmospheres, meteorites, and comets.
Phase field modeling of dislocations and obstacles in InSb
Authors: Kim Hyojung , Zimmerman Alexandra , Beyerlein Irene J. , Hunter Abigail
Published: July 2022

We present a phase-field dislocation dynamics (PFDD) model informed by first-principle calculations to elucidate the competitive dislocation nucleation and propagation between the glide and shuffle sets in InSb diamond cubic crystal. The calculations are directly informed with generalized stacking fault energy curves on the (111) slip plane for both the “glide set,” with the smaller interplanar spacing, and the “shuffle set,” with the larger interplanar spacing. The formulation also includes elastic anisotropy and the gradient term associated with the dislocation core. The PFDD calculations show that under no stress the equilibrium structure of screw glide set dislocations dissociates into Shockley partials, while those of the shuffle set dislocations do not dissociate, remaining compact. The calculated dislocation core widths of these InSb dislocations agree well with the measured values for other semiconductor materials, such as Si and GaN. We find that a shuffle set dislocation emits from a dislocation source at an applied stress about three times smaller than that needed to emit leading and trailing partials successively on the glide set plane. Once the partial dislocations in the glide set are emitted, they propagate faster than the shuffle set perfect dislocation at the same stress level.
A simple approach for characterizing the spatially varying sensitivity of microchannel plate detectors
Authors: Aglagul Denis , Kaufman Brian , Cheng Chuan , Weinacht Thomas , Saule Tobias , Trallero-Herrero Carlos A. , Nomerotski Andrei
Published: July 2022

We present a simple approach to characterize the spatial variation of the gain in microchannel plate (MCP) coupled to phosphor detectors using single electron or photon hits. The technique is easy to implement and general enough to be extended to other kinds of detectors. We demonstrate the efficacy of the approach on both laboratory and Monte Carlo generated datasets. Furthermore, we use the approach to measure the variation in gain over time as the MCP is exposed to an increasing number of electrons.
III-Nitride p-down green (520 nm) light emitting diodes with near-ideal voltage drop
Authors: Rahman Sheikh Ifatur , Jamal-Eddine Zane , Dominic Merwin Xavier Agnes Maneesha , Armitage Robert , Rajan Siddharth
Published: July 2022

We demonstrate p-down green emitting LEDs with low turn-on voltage enabled by efficient tunnel junctions. Due to the polarization field alignment in the (In,Ga)N/GaN interface with the p-down orientation, the electrostatic depletion barrier for electron and hole injection is reduced when compared with the conventional p-up LEDs. A single (In,Ga)N/GaN heterostructure quantum well active region with a GaN homojunction tunnel junction exhibited very low forward operating voltage of 2.42 V at 20 A/cm2 with a peak electroluminescence emission wavelength of 520 nm for current densities above 100 A/cm2. The bottom tunnel junction with minimal voltage drop enabled excellent hole injection into the bottom p-GaN layer.
Enhanced electrochemical actuation of nanoporous gold-polypyrrole hybrid under load
Authors: Li J. , Markmann J. , Mameka N.
Published: July 2022

This work examines the actuation strain response of a nanoporous gold-polypyrrole electrochemical actuator under compression. The strain is monitored by in situ dilatometry and dynamic mechanical analysis when the material is wetted by an aqueous electrolyte and subjected to cyclic potential variation under various compressive loads ranging from −0.27 to −22.30 MPa. Contrary to previous studies that report reduced actuation amplitudes under load in the individual constituents of the material—nanoporous gold and polypyrrole, we find the strain amplitudes of the hybrid increase with increasing load and even while being deformed by plastic deformation. In this contribution, we discuss the phenomenon by taking into account the variations of the effective Young's modulus of the material that occur simultaneously with the actuation.
Quantum correlations of exciton–polaritons induced by magnetic field
Authors: Abdalla A. S. , Alameen Suliman , Ayuel K. , Mohamed Dafalla Ahmed , Fadol Nooreldin
Published: July 2022

From the canonical and rotating-wave transformations, we obtained the effective lower-polariton Hamiltonian depending on the applied magnetic field from the coupling of one of the quantum-well excitons and photons in a semiconductor microcavity. When the pump field is circularly polarized, the nonlinear interaction can induce a strong polariton blockade near the resonant peaks, which can be suppressed by a large pump in weak magnetic field situations. Thus, the platform behavior in the variation of the polariton occupation proves the polariton quantum blockade. On the other hand, when the pump field is linearly polarized, we achieve a single-photon emitter whose polariton polarization can be adjusted by an applied magnetic field. Polaritons with opposite spins, on the other hand, are anti-bunching in the lower excitation regime and become bunching only in weak magnetic field situations and a high excitation regime. Our findings constitute a potential step toward the realization of strongly coupled polaritonic systems.
Long-distance polarizing microscope system combined with solenoid-type magnet for microscopy and simultaneous measurement of physical parameters
Authors: Kinoshita Y. , Miyakawa T. , Xu X. , Tokunaga M.
Published: July 2022

We have developed a long-distance polarizing microscope system combined with a solenoid-type superconducting magnet. By inserting an infinity-corrected objective lens into the magnet, direct or polarizing microscope images are observed in magnetic fields of up to 12 T at various temperatures down to 2 K. Through magneto-optical measurements in the transmission geometry, the local magnetization process of a transparent magnet is evaluated in areas of 10 × 10 µm2. This system enables simultaneous measurements of other physical properties over a wide range of temperatures and magnetic fields. The basic principle of the proposed long-distance microscopy can be applied to imaging experiments in various research fields, particularly biology and chemistry.
Spin–orbit torque generation in bilayers composed of CoFeB and epitaxial SrIrO3 grown on an orthorhombic DyScO3 substrate
Authors: Hori Sosuke , Ueda Kohei , Kida Takanori , Hagiwara Masayuki , Matsuno Jobu
Published: July 2022

We report on the highly efficient spin–orbit torque (SOT) generation in epitaxial SrIrO3 (SIO), which is grown on an orthorhombic DyScO3(110) substrate. By conducting harmonic Hall measurement in Co20Fe60B20 (CoFeB)/SIO bilayers, we characterize two kinds of the SOTs, i.e., dampinglike (DL) and fieldlike ones to find that the former is much larger than the latter. By comparison with the Pt control sample with the same CoFeB thickness, the observed DL SOT efficiency ξDL of SIO (∼0.32) is three times higher than that of Pt (∼0.093). The ξDL is nearly constant as a function of the CoFeB thickness, suggesting that the SIO plays a crucial role in the large SOT generation. These results on the CoFeB/SIO bilayers highlight that the epitaxial SIO is promising for low-current and reliable spin–orbit torque-controlled devices.