scholarly journals The Effect of Glass-cracking during Cooling in Liquid Nitrogen on Viability of Mint Shoot Tips

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 874D-874
Author(s):  
L.E. Towill
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Liquid Nitrogen ◽  
Plant Species ◽  
Room Temperature ◽  
Shoot Formation ◽  
Shoot Tips ◽  
Vitrification Solution

Cryopreservation using vitrification has been reported for several plant species. Shoot tips and vitrification solution were placed in semen straws and immersed in liquid nitrogen (LN). Cracking of the external glass occurred, but may be avoided by annealing slightly below the glass transition temperature before immersion. A varying percentage still cracked with some vitrification solutions. Rapid warming also can cause cracking. There is concern that cracking may reduce viability. Shoot tips from Mentha species were used to examine this problem. Glass cracking during either cooling or warming did not produce visible damage to shoot tips. Viability of shoot tips from tubes that cracked during cooling was not different from those that did not crack; however, shoot formation was slightly reduced. Cracking upon warming did not reduce viability nor shoot formation. Very slow warming reduced viability, but warming in either water or air (room temperature) gave higher levels of survival.

Silk Polymer Coating with Low Dielectric Constant and High Thermal Stability for Ulsi Interlayer Dielectric

1997 ◽  
Vol 476 ◽  
Author(s):  
P. H. Townsend ◽  
S. J. Martin ◽  
J. Godschalx ◽  
D. R. Romer ◽  
D. W. Smith ◽  
...  
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Integrated Circuits ◽  
Room Temperature ◽  
Polymer Network ◽  
Flow Characteristics ◽  
Interlayer Dielectric

AbstractA novel polymer has been developed for use as a thin film dielectric in the interconnect structure of high density integrated circuits. The coating is applied to the substrate as an oligomeric solution, SiLK*, using conventional spin coating equipment and produces highly uniform films after curing at 400 °C to 450 °C. The oligomeric solution, with a viscosity of ca. 30 cPs, is readily handled on standard thin film coating equipment. Polymerization does not require a catalyst. There is no water evolved during the polymerization. The resulting polymer network is an aromatic hydrocarbon with an isotropie structure and contains no fluorine.The properties of the cured films are designed to permit integration with current ILD processes. In particular, the rate of weight-loss during isothermal exposures at 450 °C is ca. 0.7 wt.%/hour. The dielectric constant of cured SiLK has been measured at 2.65. The refractive index in both the in-plane and out-of-plane directions is 1.63. The flow characteristics of SiLK lead to broad topographic planarization and permit the filling of gaps at least as narrow as 0.1 μm. The glass transition temperature for the fully cured film is greater than 490 °C. The coefficient of thermal expansivity is 66 ppm/°C below the glass transition temperature. The stress in fully cured films on Si wafers is ca. 60 MPa at room temperature. The fracture toughness measured on thin films is 0.62 MPa m ½. Thin coatings absorb less than 0.25 wt.% water when exposed to 80% relative humidity at room temperature.

The Effect of Thermal History on Porcelain Expansion Behavior

1989 ◽  
Vol 68 (9) ◽  
pp. 1313-1315 ◽  
Author(s):  
C.W. Fairhurst ◽  
D.T. Hashinger ◽  
S.W. Twiggs
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Room Temperature ◽  
Heating Rates ◽  
Thermal Expansion Data ◽  
Temperature Range ◽  
Expansion Behavior

Porcelain-fused-to-metal restorations are fired several hundred degrees above the glass-transition temperature and cooled rapidly through the glass-transition temperature range. Thermal expansion data from room temperature to above the glass-transition temperature range are important for the thermal expansion of the porcelain to be matched to the alloy. The effect of heating rate during measurement of thermal expansion was determined for NBS SRM 710 glass and four commercial opaque and body porcelain products. Thermal expansion data were obtained at heating rates of from 3 to 30°C/min after the porcelain was cooled at the same rate. By use of the Moynihan equation (where Tg systematically increases in temperature with an increase in cooling/heating rate), the glass-transition temperatures (Tg) derived from these data were shown to be related to the heating rate.

A carbon nanotube–epoxy interface improved damping below the glass transition temperature

RSC Advances ◽  
2016 ◽  
Vol 6 (25) ◽  
pp. 21271-21276 ◽  
Author(s):  
Yung-Chi Chu ◽  
Ming-Hsiao Weng ◽  
Wen-Yi Lin ◽  
Hsin-Jung Tsai ◽  
Wen-Kuang Hsu
Keyword(s):  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Room Temperature ◽  
Viscous Drag

Composites made from fibers and epoxy display a low viscous drag and are rarely used as mechanical dampers at room temperature.

scholarly journals Brewer’s spent yeast as wall material for microencapsulation of food compounds

2019 ◽  
Author(s):  
Rafaela Polessi Saturno ◽  
Miriam Dupas Hubinger ◽  
Gabriela Vollet Marson
Keyword(s):  
Ascorbic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Room Temperature ◽  
Core Material ◽  
Wall Material ◽  
Operational Conditions ◽  
Particle Stability ◽  
Brewer’S Spent Yeast

The brewer's spent yeast hydrolyzed precipitate was used as wall material for microencapsulation of ascorbic acid by the spray drying technique. The wall material had its centesimal composition determined as well as some physicochemical aspects: surface charge, surface tension and glass transition temperature, in order to study the behavior of the material after being atomized and to identify the most suitable core material. Operational conditions were also studied in the spray dryer. After microencapsulation, a 64% yield and a microencapsulation efficiency of 100% were achieved. Microparticle analyses showed low values of water activity and high glass transition temperature, indicating absence of microbiological activity and great particle stability at room temperature, respectively, suggesting that this wall material is suitable for protecting the ascorbic acid.

Tissue Scaffold Engineering by Micro-Stamping

2014 ◽  
Vol 1626 ◽  
Author(s):  
Eric C. Schmitt ◽  
Robert D. White ◽  
Amrit Sagar ◽  
Thomas P. James
Keyword(s):  
Tissue Engineering ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Room Temperature ◽  
Polymer Membranes ◽  
Tissue Scaffold ◽  
Brittle Behavior ◽  
Excessive Strain ◽  
Hot Melt

ABSTRACTA hand operated benchtop stamping press was developed to conduct research on microscale hole fabrication in polymer membranes for applications as scaffolds in tissue engineering. A biocompatible and biodegradable polymer, poly(ε-caprolactone), was selected for micropunching. Membranes between 30 μm and 50 μm thick were fabricated by hot melt extrusion, but could not be stamped with a 200 μm circular punch at room temperature, regardless of die clearance due to excessive strain to fracture. This problem was overcome by cooling the membrane and die sets with liquid nitrogen to take advantage of induced brittle behavior below the polymer’s glass transition temperature. While cooled, 203 μm hole patterns were successfully punched in 33 μm thick poly(ε-caprolactone) membranes with 11% die clearance, achieving 71% porosity.

scholarly journals Mechanical & Thermal Properties of Epoxy Based Hybrid Composites Reinforced with Jute/Sansevieria cylindrica Fibres

2014 ◽  
Vol 38 ◽  
pp. 191-197 ◽  
Author(s):  
M. Ashok Kumar ◽  
G. Ramachandra Reddy
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Room Temperature ◽  
Hybrid Composites ◽  
Fibre Length ◽  
Decomposition Temperature ◽  
Weight Room ◽  
Tga And Dsc

Tensile properties are studied to assess the influence of fiber weight. Room temperature cured epoxy was impregnated with jute/Scin order to evaluate the performance of hybrid composites. Jute/Scfibers are taken in the 1:1 weight ratios to suspend on epoxy resin with different fiber lengths such as 1, 2, 3 and 4 cm. The variations of aforementioned properties on hybrid composites with different fiber lengths have been studied. Significant improvement in tensile strengths of the jute/Schybrid composites has been observed by the alkali treatments. Thermal properties such as TGA and DSC are studied to investigate the influence of change in fibre length on treated and untreated hybrid composites in which 4 °C rise in decomposition temperature, 3 °C rise for glass transition temperature respectively

scholarly journals Effect of the Duration of Liquid Nitrogen Storage on the Regrowth of Blackberry Cryopreserved by Droplet Vitrification

2017 ◽  
Vol 66 (1-2) ◽  
pp. 44-50
Author(s):  
Tatjana Vujović ◽  
Đurđina Ružić ◽  
Radosav Cerović
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Shoot Tips ◽  
Lower Survival Rate ◽  
Droplet Vitrification ◽  
Vitrification Solution ◽  
Long Term Preservation ◽  
Direct Immersion

SummaryIn vitro shoot tips of the blackberry cultivar ‘Čačanska Bestrna’ were cryopreserved using the droplet vitrification technique. Upon loading (30 min) in a solution of 1.9 M glycerol and 0.5 M sucrose, the explants were dehydrated for 40 min on ice with the PVS A3 vitrification solution (glycerol 37.5%, dimethyl sulfoxide 15%, ethylene glycol 15% and sucrose 22.5%) and for 40 min at room temperature with the PVS3 solution (glycerol 50% and sucrose 50%). They were subsequently frozen in individual microdroplets of vitrification solution, by direct immersion in liquid nitrogen (LN), and kept therein for 2, 4, 8 and 24 h. The explant rewarming was performed in an unloading solution (0.8 M sucrose) for 30 min at room temperature. The duration of LN exposure did not exert significant effects on the survival and regrowth of explants in both types of vitrification solutions. The survival and regrowth of cryopreserved shoot tips dehydrated with PVS3 solution ranged between 90–95% and 80–90%, respectively. However, dehydration with PVS A3 resulted in a lower survival rate (80–90%) and a considerably lower regrowth rate (55–65%) of explants. Monitoring the shoots regenerated in the in vitro culture revealed their normal capacity for multiplication and rooting in comparison with the controls, which fully confirms the purpose of cryopreservation in the long-term preservation of plant material.

scholarly journals Self-Sensing Carbon Nanotube Composites Exposed to Glass Transition Temperature

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 259 ◽  
Author(s):  
Sung-Hwan Jang ◽  
Long-Yuan Li
Keyword(s):  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mechanical Behavior ◽  
Epoxy Matrix ◽  
Room Temperature ◽  
Epoxy Composites ◽  
Nanotube Composites ◽  
Proportional Relationship

This paper reported the effect of high temperature on the electro-mechanical behavior of carbon nanotube (CNT) reinforced epoxy composites. CNT/epoxy composites were fabricated by dispersing CNTs in the epoxy matrix using a solution casting method. Electrical conductivity measurements obtained for the CNT/epoxy composites indicated a steadily increasing directly proportional relationship with CNT concentration with a percolation threshold at 0.25 wt %, reaching a maximum of up to 0.01 S/m at 2.00 wt % CNTs. The electro-mechanical behavior of CNT/epoxy composites were investigated at a room temperature under the static and cyclic compressive loadings, resulting that the change in resistance of CNT/epoxy composites was reduced as increasing CNT concentration with good repeatability. This is due to well-networked CNTs conducting pathways created within the solid epoxy matrix observed by scanning electron microscopy. Temperature significantly affects the electro-mechanical behavior of CNT/epoxy composites. In particular, the electro-mechanical behavior of CNT/epoxy composites below the glass transition temperature showed the similar trend with those at room temperature, whereas the electro-mechanical behavior of CNT/epoxy composites above the glass transition temperature showed an opposite change in resistance with poor repeatability due to unstable CNT network in epoxy matrix.

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