Turbulent Convection in a Czochralski Silicon Melt

1999 ◽  
Vol 121 (4) ◽  
pp. 1027-1041 ◽  
Author(s):  
T. Zhang ◽  
F. Ladeinde ◽  
V. Prasad
Keyword(s):  
Growth Conditions ◽  
Crucible Wall ◽  
Combined Effects ◽  
Dynamic Adjustment ◽  
Volume Calculation ◽  
Rotation Rates ◽  
Growth System ◽  
Melt Convection ◽  
The Individual ◽  
Crucible Rotation

The individual and combined effects of buoyancy, crystal rotation, and crucible rotation are reported in this paper for axisymmetrically averaged melt convection in a large Czochralski crystal growth system for silicon. These body force effects are characterized by the respective parameters of Grashof number, Gr, rotational Reynolds number, Rer, and the Marangoni number, Ma. The range investigated consists of 108 ≤ Gr ≤ 1010, 103 ≤ Re ≤ 3 × 104, and 103 ≤ Ma ≤ 104, which is appropriate for the real Czochralski system. The studies are based on a multizone, adaptive, finite volume calculation. Validations of the numerical procedures are presented, including a grid convergence study. The effects of buoyancy and rotation on melt convection are discussed in detail. When the crystal and crucible both rotate at the same speed, but in opposite directions, without buoyancy, the effect of the crucible rotation is stronger. The rotation induces turbulence, contrary to what the literature suggests. For the combined effects, the intensity of turbulence and the average Nusselt number at the crucible wall are largest when buoyancy is slightly dominant over rotation. High rotation rates generate temperature oscillations in the presence of high Grashof numbers. Because of the consequence of oscillation for crystal quality, a dynamic adjustment of the rotation rate might be necessary in order to obtain desirable growth conditions.

Growth of Different Crystals Using a Modified Bridgman System

2007 ◽  
Author(s):  
Jiuan Wei ◽  
Lili Zheng ◽  
Hui Zhang
Keyword(s):  
Numerical Simulations ◽  
Large Diameter ◽  
Growth Conditions ◽  
Bridgman Technique ◽  
Growth Interface ◽  
Interface Stability ◽  
Growth System ◽  
Melt Convection ◽  
Prandtl Numbers ◽  
Two Parameters

This paper studies the favorable growth conditions for the III-V and II-VI crystals such as InAs, InSb, GaSe, GaP, PbTe and CdTe by the Bridgman technique. Numerical simulations have been conducted to investigate the flow field, temperature distribution in relation to the solidification interface shape and growth conditions for various materials. It is concluded that the growth is strongly affected by melt convection; a strong convection may destroy the interface stability, resulting in failed growth. The Grashof and Prandtl numbers are identified as the key parameters affecting the growth interface stability. Based on these two parameters, a growth process map is developed to quantify the difficulty of growth for different materials by Bridgman technique. To accommodate the growth of large diameter crystal, a new growth system based on Bridgman configuration is proposed in which two hot-zone furnace is introduced and the feasibility of using this system to suppress the melt convection, subsequently generating favorable growth conditions has been confirmed from the numerical simulations.

scholarly journals Impacts of stroke and cognitive impairment on activities of daily living in the Taiwan longitudinal study on aging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pi-Hsia Lee ◽  
Ting-Ting Yeh ◽  
Hsin-Yen Yen ◽  
Wan-Ling Hsu ◽  
Valeria Jia-Yi Chiu ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Longitudinal Study ◽  
Activities Of Daily Living ◽  
Daily Living ◽  
Skill Training ◽  
Community Dwelling ◽  
Combined Effects ◽  
Stroke Group ◽  
The Individual ◽  
Community Dwelling Older Adults

AbstractStroke and cognitive impairment are common in older population. They often occur together and their combined effects significantly increase disability in both basic (BADLs) and instrumental (IADLs) activities of daily living. We investigated the individual and combined impacts of stroke and cognitive impairment on BADLs and IADLs. A total of 3331 community-dwelling older adults were enrolled from the Taiwan longitudinal study on aging in 2011. Both BADLs and IADLs were analyzed. Combination of stroke and cognitive impairment increased severity of ADL disabilities, but similar prevalence, similar numbers of summed BADL and IADL tasks with disability, and similar levels of difficulty for each BADL and IADL task were found between the stroke group and cognitive impairment group. The former had more difficult in dressing while the latter had more difficult in using the telephone, transport, and managing finances. A hierarchy of ADLs was also observed in all groups. ADL skill training supplemented with cognitive and physical interventions should focus on secondary prevention of dementia and improve motor functional capacity to reduce loss of ADLs.

Signaling Effects: Increased Content Retention and New Answers—Part II

1989 ◽  
Vol 19 (4) ◽  
pp. 395-415 ◽  
Author(s):  
Jan H. Spyridakis
Keyword(s):  
Research Methods ◽  
Expository Text ◽  
Combined Effects ◽  
Good Readers ◽  
Logical Connectives ◽  
Content Retention ◽  
The Individual

This study investigated the role of signaling in helping good readers comprehend expository text. As the existing literature on signaling, reviewed in the last issue of this Journal, pointed to deficiencies in previous studies' methodologies, one goal of this study was to refine prose research methods. Two passages were designed in one of eight signaled versions each. The design was constructed to assess the individual and combined effects of headings, previews, and logical connectives. The study also assessed the effect of passage length, familiarity, and difficulty. The results showed that signals do improve a reader's comprehension, particularly comprehension two weeks after the reading of a passage and comprehension of superordinate and superordinate inferential information. This study supports the hypothesis that signals can influence retention of text-based information, particularly with long, unfamiliar, or difficult passages.

scholarly journals In Vitro Evaluation of the Individual and Combined Cytotoxic and Estrogenic Effects of Zearalenone, Its Reduced Metabolites, Alternariol, and Genistein

2021 ◽  
Vol 22 (12) ◽  
pp. 6281
Author(s):  
Adrienn Balázs ◽  
Zelma Faisal ◽  
Rita Csepregi ◽  
Tamás Kőszegi ◽  
Balázs Kriszt ◽  
...  
Keyword(s):  
Dietary Supplements ◽  
Filamentous Fungi ◽  
Combined Effects ◽  
In Vitro Evaluation ◽  
Estrogenic Effects ◽  
Toxic Metabolites ◽  
Alternaria Toxins ◽  
The Individual

Mycotoxins are toxic metabolites of filamentous fungi. Previous studies demonstrated the co-occurrence of Fusarium and Alternaria toxins, including zearalenone (ZEN), ZEN metabolites, and alternariol (AOH). These xenoestrogenic mycotoxins appear in soy-based meals and dietary supplements, resulting in the co-exposure to ZEN and AOH with the phytoestrogen genistein (GEN). In this study, the cytotoxic and estrogenic effects of ZEN, reduced ZEN metabolites, AOH, and GEN are examined to evaluate their individual and combined impacts. Our results demonstrate that reduced ZEN metabolites, AOH, and GEN can aggravate ZEN-induced toxicity; in addition, the compounds tested exerted mostly synergism or additive combined effects regarding cytotoxicity and/or estrogenicity. Therefore, these observations underline the importance and the considerable risk of mycotoxin co-exposure and the combined effects of mycoestrogens with phytoestrogens.

scholarly journals Size control models of Saccharomyces cerevisiae cell proliferation.

1982 ◽  
Vol 2 (4) ◽  
pp. 361-368 ◽  
Author(s):  
A E Wheals
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Proliferation ◽  
Critical Size ◽  
Transition Probability ◽  
Size Control ◽  
Time Lapse ◽  
Growth Conditions ◽  
Yeast Cells ◽  
Cycle Times ◽  
The Individual

By using time-lapse photomicroscopy, the individual cycle times and sizes at bud emergence were measured for a population of saccharomyces cerevisiae cells growing exponentially under balanced growth conditions in a specially constructed filming slide. There was extensive variability in both parameters for daughter and parent cells. The data on 162 pairs of siblings were analyzed for agreement with the predictions of the transition probability hypothesis and the critical-size hypothesis of yeast cell proliferation and also with a model incorporating both of these hypotheses in tandem. None of the models accounted for all of the experimental data, but two models did give good agreement to all of the data. The wobbly tandem model proposes that cells need to attain a critical size, which is very variable, enabling them to enter a start state from which they exit with first order kinetics. The sloppy size control model suggests that cells have an increasing probability per unit time of traversing start as they increase in size, reaching a high plateau value which is less than one. Both models predict that the kinetics of entry into the cell division sequence will strongly depend on variability in birth size and thus will be quite different for daughters and parents of the asymmetrically dividing yeast cells. Mechanisms underlying these models are discussed.

Using factorial mediation analysis to better understand the effects of interventions

2021 ◽  
Author(s):  
Jillian C Strayhorn ◽  
Linda M Collins ◽  
Timothy R Brick ◽  
Sara H Marchese ◽  
Angela Fidler Pfammatter ◽  
...  
Keyword(s):  
Mediation Analysis ◽  
Factorial Experiment ◽  
Combined Effects ◽  
Optimization Strategy ◽  
Testing Hypotheses ◽  
Causal Mechanisms ◽  
Multiphase Optimization Strategy ◽  
Factorial Optimization ◽  
The Individual ◽  
Advance Theory

Abstract To improve understanding of how interventions work or why they do not work, there is need for methods of testing hypotheses about the causal mechanisms underlying the individual and combined effects of the components that make up interventions. Factorial mediation analysis, i.e., mediation analysis applied to data from a factorial optimization trial, enables testing such hypotheses. In this commentary, we demonstrate how factorial mediation analysis can contribute detailed information about an intervention’s causal mechanisms. We briefly review the multiphase optimization strategy (MOST) and the factorial experiment. We use an empirical example from a 25 factorial optimization trial to demonstrate how factorial mediation analysis opens possibilities for better understanding the individual and combined effects of intervention components. Factorial mediation analysis has important potential to advance theory about interventions and to inform intervention improvements.

scholarly journals The individual and combined effects of snowmelt timing and frost exposure on the reproductive success of montane forbs

2019 ◽  
Vol 107 (4) ◽  
pp. 1970-1981 ◽  
Author(s):  
Gabriella L. Pardee ◽  
Isaac O. Jensen ◽  
David W. Inouye ◽  
Rebecca E. Irwin
Keyword(s):  
Reproductive Success ◽  
Combined Effects ◽  
The Individual

scholarly journals The Individual and Combined Effects of Deoxynivalenol and Aflatoxin B1 on Primary Hepatocytes of Cyprinus Carpio

2010 ◽  
Vol 11 (10) ◽  
pp. 3760-3768 ◽  
Author(s):  
Cheng-Hua He ◽  
Yan-Hong Fan ◽  
Ying Wang ◽  
Chao-Ying Huang ◽  
Xi-Chun Wang ◽  
...  
Keyword(s):  
Cyprinus Carpio ◽  
Aflatoxin B1 ◽  
Combined Effects ◽  
Primary Hepatocytes ◽  
The Individual
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