Thermal stress as the major factor of defect generation in SiC during PVT growth

2002 ◽  
Vol 742 ◽  
Author(s):  
D. I. Cherednichenko ◽  
R. V. Drachev ◽  
I. I. Khlebnikov ◽  
X. Deng ◽  
T. S. Sudarshan
Keyword(s):  
Plastic Deformation ◽  
Thermal Stress ◽  
Diffusion Processes ◽  
High Stress ◽  
Structural Quality ◽  
Second Phase ◽  
Temperature Field Distribution ◽  
Self Diffusion ◽  
Critical Resolved Shear Stress

ABSTRACTNumerical simulations of the thermal stress distribution in a SiC boule 2” in diameter and 1” long grown by conventional PVT technique were performed based on the temperature field distribution in a resistively heated growth reactor that was simulated using the GAMBIT-2.0.4/FIDAP-8.6.2 software package. Analysis of the simulation results revealed the existence of a thermal stress, which was excessively nonuniform in distribution and whose magnitude exceeded the value of the critical resolved shear stress of 1.0 MPa by a factor of 2. The high stress initiated plastic deformation and the high temperature provoked the intense self-diffusion processes. The combination of these factors alters the mechanism of plastic deformation, significantly affecting the structural quality of the growing crystal. The influence of self-diffusion processes initiating the formation of interstitial atoms and vacancies; stacking fault formation as a result of the nonconservative motion of the basal plane dislocations; and micropipe formation from the dislocation groups piled up at silicon and carbon second phase inclusions are also discussed.

Thermo-mechanical characteristics of the stretchable serpentine-patterned microelectrode

2018 ◽  
Vol 11 (03) ◽  
pp. 1850054 ◽  
Author(s):  
Myoungwoo Lee ◽  
Hyun-Oh Kim ◽  
Jin-Hyo Boo ◽  
Youn-Jea Kim
Keyword(s):  
Thermal Stress ◽  
Mechanical Characteristics ◽  
Von Mises Stress ◽  
Comsol Multiphysics ◽  
Structural Quality ◽  
Wearable Electronics ◽  
Stress Distributions ◽  
Commercial Code ◽  
Von Mises

Stretchable microelectrode is applied in various fields, such as sensory skins for soft robotics and wearable electronics for biomedical patches, etc. The structural quality of the stretchable microelectrode is a significant factor since it influences the thermo-mechanical characteristics. In order to improve the structural quality of the electrode, a serpentine-patterned configuration with various curvature angles of 60[Formula: see text], 90[Formula: see text] and 120[Formula: see text] were applied to the film of each electrode. In addition, thermal stress was applied at certain voltages to demonstrate the thermo-mechanical characteristics of the serpentine-patterned microelectrode. The numerical analysis on von Mises stress and thermal stress of the electrode was conducted with a commercial code, COMSOL Multiphysics ver. 5.3a. The results were graphically described by showing stress distributions of each case and the microelectrode having highest thermo-mechanical characteristics was derived.

Reproduction of the Roman snail (Helix pomatia L.) from a local natural population in farm conditions and in a natural habitat

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Maciej Ligaszewski ◽  
Przemysław Pol
Keyword(s):  
Natural Population ◽  
Natural Habitat ◽  
Local Population ◽  
Helix Pomatia ◽  
Second Phase ◽  
Animal Reproduction ◽  
Snail Helix Pomatia ◽  
June July ◽  
A Site

AbstractThe aim of this study was to compare the quality of clutches and reproduction results of two groups of Roman snails (Helix pomatia) from the same local population, laying eggs simultaneously in semi-natural farm conditions and in a natural habitat. The study material were Roman snails aged 2 or more years which had entered the third phenological season of their life and thus the first season of sexual maturity. Observations were conducted at an earthen enclosure in a greenhouse belonging to the experimental farm for edible snails at the National Research Institute of Animal Reproduction in Balice near Kraków (Poland) as well as at a site where a local population naturally occurs in the uncultivated park surrounding the Radziwiłł Palace. In the June-July season, differences among such parameters as weight of clutch, number of eggs in clutch, mean egg weight, and hatchling percentage when compared to the total number of eggs in the clutch were compared. It was determined that clutches of eggs from the natural population laid in the greenhouse were of lesser weight (P<0.01), contained fewer eggs (P<0.05), and the mean weight of individual eggs was less (P<0.05) than in clutches laid simultaneously in a natural habitat. Both in the greenhouse and the natural habitat, in the first phase of laying eggs (June) the weight of the clutch and number of eggs its contained were greater than in the second phase (July). However, only for snails laying eggs in the greenhouse were these differences statistically significant (P<0.05) and highly significant (P<0.01), respectively. Statistically significant differences were not observed in hatchling percentage between eggs laid in the greenhouse and the natural habitat. The lower number of eggs laid in the farmed conditions of the greenhouse was successfully compensated for by the absence of mass destruction by rodents which occurred in the natural habitat.

ВЛИЯНИЕ ТВЕРДОФАЗНОЙ РЕКРИСТАЛЛИЗАЦИИ С ДВОЙНОЙ ИМПЛАНТАЦИЕЙ НА ПЛОТНОСТЬ СТРУКТУРНЫХ ДЕФЕКТОВ В УЛЬТРАТОНКИХ СЛОЯХ КРЕМНИЯ НА САПФИРЕ

2020 ◽  
Vol 96 (3s) ◽  
pp. 154-159
Author(s):  
Н.Н. Егоров ◽  
С.А. Голубков ◽  
С.Д. Федотов ◽  
В.Н. Стаценко ◽  
А.А. Романов ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Solid Phase ◽  
Modern Method ◽  
Structural Defects ◽  
Structural Quality ◽  
Mos Transistors ◽  
Ultrathin Layers ◽  
Heteroepitaxial Layers ◽  
Xrd And Tem

Высокая плотность структурных дефектов является основной проблемой при изготовлении электроники на гетероструктурах «кремний на сапфире» (КНС). Современный метод получения ультратонких структур КНС с помощью твердофазной эпитаксиальной рекристаллизации позволяет значительно снизить дефектность в гетероэпитаксиальном слое КНС. В данной работе ультратонкие (100 нм) слои КНС были получены путем рекристаллизации и утонения субмикронных (300 нм) слоев кремния на сапфире, обладающих различным структурным качеством. Плотность структурных дефектов в слоях КНС оценивалась с помощью рентгеноструктурного анализа и просвечивающей электронной микроскопии. Кривые качания от дифракционного отражения Si(400), полученные в ω-геометрии, продемонстрировали максимальную ширину на полувысоте пика не более 0,19-0,20° для ультратонких слоев КНС толщиной 100 нм. Формирование структурно совершенного субмикронного слоя КНС 300 нм на этапе газофазной эпитаксии обеспечивает существенное уменьшение плотности дислокаций в ультратонком кремнии на сапфире до значений ~1 • 104 см-1. Тестовые n-канальные МОП-транзисторы на ультратонких структурах КНС характеризовались подвижностью носителей в канале 725 см2 Вс-1. The high density of structural defects is the main problem on the way to the production of electronics on silicon-on-sapphire (SOS) heteroepitaxial wafers. The modern method of obtaining ultrathin SOS wafers is solid-phase epitaxial recrystallization which can significantly reduce the density of defects in the SOS heteroepitaxial layers. In the current work, ultrathin (100 nm) SOS layers were obtained by recrystallization and thinning of submicron (300 nm) SOS layers, which have various structural quality. The density of structural defects in the layers was estimated by using XRD and TEM. Full width at half maximum of rocking curves (ω-geometry) was no more than 0.19-0.20° for 100 nm ultra-thin SOS layers. The structural quality of 300 nm submicron SOS layers, which were obtained by CVD, depends on dislocation density in 100 nm ultrathin layers. The dislocation density in ultrathin SOS layers was reduced by ~1 • 104 cm-1 due to the utilization of the submicron SOS with good crystal quality. Test n-channel MOS transistors based on ultra-thin SOS wafers were characterized by electron mobility in the channel 725 cm2 V-1 s-1.

Avascular necrosis of the femoral head: Evaluation of hyperbaric oxygen therapy and quality of life

2020 ◽  
pp. 561-569
Author(s):  
Angeliki Chandrinou ◽  
◽  
Anna Korompeli ◽  
Eirini Grammatopoulou ◽  
Konstantina Gaitanou ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Femoral Head ◽  
Avascular Necrosis ◽  
Hyperbaric Oxygen ◽  
Hyperbaric Oxygen Therapy ◽  
Oxygen Therapy ◽  
Harris Hip Score ◽  
Controlled Study ◽  
Second Phase

Introduction: The treatment of avascular necrosis of the femoral head (AVNFH) is based on invasive (e.g., core decompression) and non-invasive methods (e.g., hyperbaric oxygen therapy – HBO2). The purpose of the present study is to evaluate the effect of HBO2 on the quality of life (QoL) of patients with AVNFH. Methods: This was a prospective observational non-controlled study of patients with AVNFH treated by HBO2. It was conducted, with the use of Steinberg scale, on 73 patients with AVNFH Stage I or II who were treated with HBO2. Patients’ QoL was assessed with EuroQol-5D-5L (EQ), Harris Hip Score (mHHS), MAHORN (MHOT), and VAS, in three different phases: before HBO2; after the completion of the first phase (20 HBO2 sessions, up to two months); and after the completion of the second phase (20 HBO2 sessions, up to two months after the first phase). A reassessment was made on the completion of each phase. Ratings were also made after the completion of each phase, over the first five months of follow-up. Results: All 73 patients (67.1% males, 32.9% females, mean age: 40.34, SD ± 9.99) participated in the study. Steinberg scale, mean EQ (F (1, 57) = 25.18, η2 = .306 and F (1, 43) = 43.402, η2 = .502); mHHS (F (1, 61) = 67.13, η2 = .524) and F (1, 43) = 31.84, η2 = .425); MHOT (F (1, 61) = 11.68, η2 = .161) and F (1, 43) = 98.01, η2 = .695); and VAS (F (1, 53) = 24.11, η2 = .313) and F (1, 39) = 45.61, η2 = .539), improved between the first and second measurements and between the second and third measurement accordingly (p < .01). Conclusions: HBO2 treatment does not induce alteration of quality of life and is well tolerated and accepted by patients.

scholarly journals Development and validation of a short version of the Sarcopenia Quality of Life questionnaire: the SF-SarQoL

2021 ◽  
Author(s):  
A. Geerinck ◽  
C. Beaudart ◽  
J.-Y. Reginster ◽  
M. Locquet ◽  
C. Monseur ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Short Form ◽  
Reduction Process ◽  
Community Dwelling ◽  
Short Version ◽  
Second Phase ◽  
Life Questionnaire ◽  
Quality Of Life Questionnaire ◽  
Two Phases

Abstract Purpose To facilitate the measurement of quality of life in sarcopenia, we set out to reduce the number of items in the previously validated Sarcopenia Quality of Life (SarQoL®) questionnaire, and to evaluate the clinimetric properties of this new short form. Methods The item reduction process was carried out in two phases. First, information was gathered through item-impact scores from older people (n = 1950), a Delphi method with sarcopenia experts, and previously published clinimetric data. In the second phase, this information was presented to an expert panel that decided which of the items to include in the short form. The newly created SFSarQoL was then administered to older, community-dwelling participants who previously participated in the SarcoPhAge study. We examined discriminative power, internal consistency, construct validity, test–retest reliability, structural validity and examined item parameters with a graded response model (IRT). Results The questionnaire was reduced from 55 to 14 items, a 75% reduction. A total of 214 older, community-dwelling people were recruited for the validation study. The clinimetric evaluation showed that the SF-SarQoL® can discriminate on sarcopenia status [EWGSOP2 criteria; 34.52 (18.59–43.45) vs. 42.86 (26.56–63.69); p = 0.043], is internally consistent (α = 0.915, ω = 0.917) and reliable [ICC = 0.912 (0.847–0.942)]. A unidimensional model was fitted (CFI = 0.978; TLI = 0.975; RMSEA = 0.108, 90% CI 0.094–0.123; SRMR = 0.055) with no misfitting items and good response category separation. Conclusions A new, 14-item, short form version of the Sarcopenia Quality of Life questionnaire has been developed and shows good clinimetric properties.

The Physical Context of Child Development

2021 ◽  
Vol 30 (1) ◽  
pp. 41-48
Author(s):  
Gary W. Evans
Keyword(s):  
Child Development ◽  
Observational Studies ◽  
Physiological Stress ◽  
Personal Characteristics ◽  
Adverse Outcomes ◽  
Structural Quality ◽  
Physical Context ◽  
Physical Setting ◽  
Physical Features

Child development reflects interactions between personal characteristics and the physical and social environment. Psychology, however, lacks analysis of physical features that influence child development. In this article, I describe a preliminary taxonomy of physical-setting characteristics that can influence child development, focusing on environmental stressors such as noise, crowding, and chaos along with structural quality of housing, day care, and schools. Adverse outcomes associated with suboptimal physical settings during childhood include cognitive and socioemotional difficulties along with chronic physiological stress. Both direct effects on the child as well as indirect effects occurring via significant persons surrounding the child are described. Methodological limitations, particularly reliance on observational studies, are a weakness in the current literature, but increasingly more rigorously obtained findings yield converging evidence of the effects of physical settings on child development.

scholarly journals Improving Stress Management and Sleep Hygiene in Intelligent Homes

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2398
Author(s):  
Asterios Leonidis ◽  
Maria Korozi ◽  
Eirini Sykianaki ◽  
Eleni Tsolakou ◽  
Vasilios Kouroumalis ◽  
...  
Keyword(s):  
Sleep Disturbances ◽  
Contextual Information ◽  
High Stress ◽  
Sleep Hygiene ◽  
Poor Sleep ◽  
Health Issues ◽  
Time Data ◽  
Intelligent Home ◽  
And Control

High stress levels and sleep deprivation may cause several mental or physical health issues, such as depression, impaired memory, decreased motivation, obesity, etc. The COVID-19 pandemic has produced unprecedented changes in our lives, generating significant stress, and worries about health, social isolation, employment, and finances. To this end, nowadays more than ever, it is crucial to deliver solutions that can help people to manage and control their stress, as well as to reduce sleep disturbances, so as to improve their health and overall quality of life. Technology, and in particular Ambient Intelligence Environments, can help towards that direction, when considering that they are able to understand the needs of their users, identify their behavior, learn their preferences, and act and react in their interest. This work presents two systems that have been designed and developed in the context of an Intelligent Home, namely CaLmi and HypnOS, which aim to assist users that struggle with stress and poor sleep quality, respectively. Both of the systems rely on real-time data collected by wearable devices, as well as contextual information retrieved from the ambient facilities of the Intelligent Home, so as to offer appropriate pervasive relaxation programs (CaLmi) or provide personalized insights regarding sleep hygiene (HypnOS) to the residents. This article will describe the design process that was followed, the functionality of both systems, the results of the user studies that were conducted for the evaluation of their end-user applications, and a discussion about future plans.

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