scholarly journals Scaling Effects on the Residual Thermomechanical Stress During Ice-Free Cooling to Storage Temperature

2020 ◽  
Vol 87 (10) ◽  
Author(s):  
Prem K. Solanki ◽  
Yoed Rabin
Keyword(s):  
Maximum Stress ◽  
Storage Temperature ◽  
Glassy State ◽  
Temperature Gradients ◽  
Scaling Effects ◽  
Glassy Material ◽  
Thermomechanical Stress ◽  
Free Cooling ◽  
High Cooling Rates ◽  
Container Shape

Abstract Cryopreservation via vitrification (glass formation) is a promising approach for long-term preservation of large-size tissues and organs. Unfortunately, thermomechanical stress, which is driven by the tendency of materials to change size with temperature, may lead to structural failure. This study focuses on analysis of thermomechanical stress in a realistic, pillow-like shape cryobag as it is cooled to cryogenic storage, subject to sufficiently high cooling rates to facilitate vitrification. Contrary to common perception, it is demonstrated in this study that the maximum stress in the specimen does not necessarily increase with increasing size of the specimen. In fact, the maximum stress is affected by the combination of two competing effects, associated with the extent of the temperature gradients within the specimen and its overall volume. On one hand, the increase in specimen size gives rise to more prominent temperature gradients, which can intensify the thermomechanical stress. On the other hand, the temperature distribution at the core of larger specimens is more uniform, which leads to a larger portion of the specimen transitioning from fluid to a glassy material almost instantaneously, which carries a moderating effect on the overall mechanical stress at the glassy state (i.e., lower residual stress). In conclusion, this study demonstrates the role of container shape optimization in reducing the thermomechanical stress during cooling.

Cytoplasmic glass formation in maize embryos

1992 ◽  
Vol 2 (4) ◽  
pp. 251-253 ◽  
Author(s):  
F. Bruni ◽  
A. C. Leopold
Keyword(s):  
Phase Diagram ◽  
Glass Transition ◽  
Electron Spin Resonance ◽  
Transition Temperature ◽  
Spin Probe ◽  
Storage Temperature ◽  
Glassy State ◽  
Sample Weight ◽  
Spin Resonance ◽  
Maize Embryos

AbstractIn order to examine the occurrence of a glassy state in the cytoplasm of maize embryos as a function of water content, isolated embryos were examined using spin-probe electron spin resonance. The glass transition temperature was determined at various degrees of hydration (h) in the range 0.05–0.25 g H2O g−1 dry sample weight. The obtained phase diagram indicates that, at standard storage temperature (−5°C), the cytoplasm of embryos drier than 0.15 g H2O g−1 is in a glassy state.

Effect of Design Parameters on Thermomechanical Stress in Silicon of Through-Silicon Via

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Joo-Sun Hwang ◽  
Seung-Ho Seo ◽  
Won-Jun Lee
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Maximum Stress ◽  
Design Parameters ◽  
Element Analysis ◽  
Through Silicon Via ◽  
Dielectric Thickness ◽  
Thermomechanical Stress ◽  
Lower Region

We examined the effect of the design parameters of a through-silicon via (TSV) on the thermomechanical stress distribution at the bottom of the TSV using finite element analysis. Static analyses were carried out at 350 °C to simulate the maximum thermomechanical stress during postplating annealing. The thermomechanical stress is concentrated in the lower region of a TSV, and the maximum stress in silicon occurs at the bottom of the TSV. The TSV diameter and dielectric liner thickness were two important determinants of the maximum stress in the silicon. The maximum stress decreased with decreasing TSV diameter, whereas the effect of aspect ratio was negligible. A thick dielectric liner is advantageous for lowering the maximum stress in silicon. The minimum dielectric thickness resulting in a maximum stress less than the yield stress of silicon was 520, 230, and 110 nm for via diameters of 20, 10, and 5 μm, respectively. The maximum stress also decreased with the thickness of the copper overburden.

Numerical Analysis of EB-PVD Thermal Barrier Coatings under Thermal-Mechanical Coupled Environment

2007 ◽  
Vol 546-549 ◽  
pp. 1795-1799 ◽  
Author(s):  
Hui Peng ◽  
Hong Bo Guo ◽  
Chun Xia Zhang ◽  
Sheng Kai Gong
Keyword(s):  
Finite Element ◽  
Thermal Barrier Coatings ◽  
Maximum Stress ◽  
Temperature Gradients ◽  
Maximum Temperature ◽  
Thermal Barrier ◽  
Fe Model ◽  
Barrier Coatings ◽  
Air Convection ◽  
Cooling Air

Numerical method was used to simulate the stress state of thermal barrier coatings (TBCs) under thermal-mechanical coupled environment. The finite element (FE) model was built as hollow tube and boundary conditions including heating rate, cooling air convection and mechanical loadings were considered. The maximum stress locates where maximum temperature gradients is formed. This failure mode is consistent with the experimental results.

scholarly journals Influence of Storage Temperature on Orthodontic Elastics

2021 ◽  
Author(s):  
R Piradhiba ◽  
Evan A Clement ◽  
Navaneetha Nambi ◽  
S Veerasankar ◽  
S Madhumitra ◽  
...  
Keyword(s):  
Maximum Stress ◽  
Storage Temperature ◽  
Control Group ◽  
Maximum Elongation ◽  
Group 4 ◽  
Significant Difference ◽  
Group 3 ◽  
Group 2 ◽  
Storage Temperatures ◽  
Group 1

Introduction: Orthodontic elastics are a very significant tool in orthodontics, as it is the most commonly used force delivering unit. Temperature plays a key role in the amount of force that elastics are able to produce. Hence, there is a need to evaluate the influence of storage temperature on the properties of orthodontic elastics before its clinical use. Aim: To evaluate the influence of different storage temperature of latex orthodontic elastics. Materials and Methods: This cross-sectional study was conducted at Sathyabama Dental College and Hospital, Chennai, in November 2019. Sample of 40 latex orthodontic elastics (TP Orthodontics, medium force, standard size of 3/16′′) were divided into four groups with 10 elastics each, based on their storage temperature and stored in closed plastic packages. Group 1 was kept as a Control group and Group 2, Group 3 and Group 4 were stored in three Incubators under the specified storage temperatures such as 26-28°C, 4-8°C, 37°C respectively. The elastics were stretched and their forces measured in six progressive increases of 100% of their inner diameter, starting at a level of 100% stretching, with the Universal Testing Machine, Instron. The samples were also tested for Maximum Stress (MPa), Maximum Force (N), Maximum Elongation (%) and Break Distance (mm). Data were analysed using Statistical Package for the Social Science (SPSS) software version 16.0, one-way Analysis of Variance (ANOVA) and post-hoc test. Results: On evaluating the stress at 100%, 200%, 300%, 400%, 500%, 600% of strain, there was no statistically significant difference between the groups. Maximum Stress MPa was found to be 24.12±3.32, 25.12±3.42, 23.3±3.41, 23.97±3.50 for group1, group 2, group 3 and group 4 respectively. Maximum Elongation (%) was found to be 1369.0±25.108, 1364.0±23.190, 1359.0±35.103, 1363.0±34.657 for group 1, group 2, group 3 and group 4, respectively. Break Distance (mm) was found to be 68.48±1.267, 68.28±1.267, 67.87±1.77 and 68.19±1.727 for group1, group 2, group 3 and group 4, respectively. And none of the parameters tested showed statistical significance between the four groups. Conclusion: Latex elastics may be stored under any of the conditions tested in the present study over a period of one month, since different storage temperatures over a period of one month did not interfere in their mechanical properties.

The Challenges Associated with the Formation of Equiaxed Grains during Additive Manufacturing of Titanium Alloys

2018 ◽  
Vol 770 ◽  
pp. 155-164 ◽  
Author(s):  
David H. St John ◽  
Stuart D. McDonald ◽  
Michael J. Bermingham ◽  
Sri Mereddy ◽  
Arvind Prasad ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Temperature Gradients ◽  
Metal Alloys ◽  
Grain Structure ◽  
Grain Structures ◽  
Columnar Grains ◽  
High Cooling Rates ◽  
Columnar Grain ◽  
Equiaxed Grains ◽  
Equiaxed Grain

It is well established that columnar grain structures usually form when metal alloys are used to additively manufacture components. A challenging goal is to produce an equiaxed grain structure throughout the component to remove anisotropy and refine the grain size in order to improve its mechanical performance. The high cooling rates and associated high temperature gradients are the main reasons for the formation of columnar grains via epitaxial growth of each added layer of material. There appear to be limited strategies for promoting equiaxed nucleation of grains. In addition to cooling rate and temperature gradient, we explore other variables such as the potency of natural or added inoculant particles and the composition of the alloy, and their possible impact on the nucleation of equiaxed grains. Although changing the composition can help, finding a suitably potent nucleant particle is a major challenge. Operating parameters can also influence the microstructure and optimization to produce equiaxed grains may be possible. The limitations of these strategies and possible ways to overcome them are evaluated.

Storage of Human Blood Platelets

1974 ◽  
Vol 32 (02/03) ◽  
pp. 405-416 ◽  
Author(s):  
M. R Hardeman ◽  
Carina J L. Heynens
Keyword(s):  
Storage Temperature ◽  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Storage Period ◽  
Serotonin Uptake ◽  
Hypotonic Shock ◽  
Glycolytic Intermediates

SummaryStorage experiments were performed at 4°, 25° and 37° C with platelet-rich plasma under sterile conditions. In some experiments also the effect of storing platelets at 4° C in whole blood was investigated.Before, during and after three days of storage, the platelets were tested at 37° C for their serotonin uptake and response to hypotonic shock. In addition some glycolytic intermediates were determined.A fair correlation was noticed between the serotonin uptake and hypotonic shock experiments. Both parameters were best maintained at 25° C. Also platelet counting, performed after the storage period, indicated 25° C as the best storage temperature. Determination of glycolytic intermediates did not justify any conclusion regarding the optimal storage temperature. Of the various anticoagulants studied, ACD and heparin gave the best results as to the serotonin uptake and hypotonic shock response, either with fresh or stored platelets. The use of EDTA resulted in the lowest activity, especially after storage.The results of these storage experiments in vitro, correspond well with those in vivo reported in the literature.

Motilitas dan Vabilitas Spermatozoa Ayam Kampung pada Suhu 5°C Menggunakan Pengencer dan Lama Simpan yang Berbeda

2018 ◽  
Vol 5 (2) ◽  
pp. 102
Author(s):  
Enike Dwi Kusumawati ◽  
Selvinus Lawu Woli ◽  
Aju Tjatur Nugroho Krisnaningsih ◽  
Waluyo Edi Susanto ◽  
Syam Rahadi
Keyword(s):  
Data Analysis ◽  
Storage Temperature ◽  
Coconut Water ◽  
Laboratory Research ◽  
Ringer Lactate ◽  
Randomized Design ◽  
Native Chicken ◽  
Lactate Solution ◽  
Better Than

ABSTRAKPenelitian ini dilakukan untuk mengetahui motilitas dan viabilitas spermatozoa ayam kampung pada suhu 5oC menggunakan pengencer dan lama simpan yang berbeda. Metode yang digunakan dalam penelitian ini adalah penelitian laboratorium menggunakan Rancangan Acak Lengkap (RAL) Faktorial dengan pengencer ringer lactat solution, air kelapa dan tanpa pengencer serta lama simpan 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, masing-masing diulang 10 kali. Variabel yang diamati yaitu motilitas dan viabilitas spermatozoa. Analisa data yang digunakan adalah analisis varian. Hasil analisis data menunjukkan bahwa motilitas dan viabilitas spermatozoa menggunakan pengencer ringer lactat solution lebih tinggi (P<0,01) serta dapat bertahan sampai lama simpan 24 jam dibandingkan air kelapa dan tanpa pengencer. Adapun nilai motilitas ringer lactat solution, air kelapa dan tanpa pengencer pada lama simpan 24 jam masing-masing sebesar 43,5±17,17%; 8±4,83%; 6,5±2,4%, sedangkan nilai viabilitasnya sebesar 83,2±7,25%; 64,6±3,20%; dan 63,1±2,33%. Kesimpulan dari hasil penelitian ini adalah ringer lactat solution lebih baik dibandingkan air kelapa dan tanpa pengencer dalam mempertahankan kualitas semen ayam kampung pada suhu simpan 5oC sampai lama simpan 24 jam.Kata Kunci : air kelapa, ayam kampung, motilitas, spermatozoa, viabilitas  ABSTRACTThis study was conducted to determine the motility and viability of spermatozoa of Native chickens at 5oC using different diluents and time storage. The method used in this study was laboratory research using Factorial Completely Randomized Design with ringer lactate solution, coconut water and without diluent at 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 hours of time storage each repeated 10 times. The variables observed were motility and viability of sperm. Data analysis used is variance analysis. The results of data analysis showed that the motility and viability of spermatozoa using ringer lactate solution diluents was higher (P <0.05) than coconut water and without diluents. The motility values of ringer lactat solution, coconut water and without diluents were 43,5±17,17%; 8±4,83%; 6,5±2,4% respectively, while the viability values were 83,2±7,25%; 64,6±3,20% and 63,1±2,33%. The conclusion of this study is that ringer lactat solution is better than coconut water an without diluents in maintaining the quality of Native chicken semen at a storage temperature of 5oC until 24 hours.Keywords: coconut water, motility, native chicken, sperm, viability

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