scholarly journals The Second Expansion Cycle in Ultramicrocellular Foams

2003 ◽  
Vol 22 (4) ◽  
pp. 260-268 ◽  
Author(s):  
A. Victoria Nawaby ◽  
Y. Paul Handa
Keyword(s):  
Low Temperature ◽  
Cell Density ◽  
Cell Walls ◽  
Density Increase ◽  
Significant Gain ◽  
Foam Density ◽  
Blowing Agent ◽  
Loading Level ◽  
Density Reduction ◽  
Rubbery Phase

Ultramicrocellular PMMA foams made from the low temperature rubbery phase, obtained by saturating the polymer with CO2 at 0°C and 34 atm, was subjected to a second expansion cycle by heating it rapidly to temperatures in the range 30 to 120°C. The blowing agent for the secondary expansion was either the residual CO2 in the foam at about 19 wt% level or fresh CO2 re-equilibrated at 0°C and 34 atm to a loading level of about 29 wt%. In the former case, the second expansion cycle led to lower foam densities whereas in the latter case it led to stretching and re-orientation of the cell walls with no significant gain in further foam density reduction or cell density increase.

Endothelial cell density change in fully dislocated XEN Gel IMPLANT after trabeculectomy: A case report

2021 ◽  
pp. 112067212198963
Author(s):  
Martina Menchini ◽  
Francesco Sartini ◽  
Filippo Tatti ◽  
Enrico Peiretti ◽  
Michele Figus
Keyword(s):  
Endothelial Cell ◽  
Anterior Chamber ◽  
Cell Density ◽  
Cell Loss ◽  
Endothelial Cell Density ◽  
Endothelial Cell Loss ◽  
Density Reduction ◽  
History Of ◽  
Cell Loss Rate

Purpose: To report a case of fully dislocated XEN Gel Implant device into the anterior chamber, 18 months after its implantation and its impact on endothelial cell density. Result: A 75-year-old man with a history of multiple glaucoma surgeries during the last three years presented with an entirely dislocated XEN Gel implant into the anterior chamber. An endothelial cell density reduction was observed over 18 months. Thus, the implant was removed. In the short-term after surgery, the endothelial cell loss rate reduced. Conclusion: XEN Gel Implant can dislocate into the anterior chamber, increasing endothelial cell loss in an eye already underwent multiple surgical procedures with subsequent adverse events. Therefore, if the implant seems displaced, the endothelial cell density should be monitored, and the length of the free-tube segment within the anterior chamber should be measured, during the patient’s follow-up.

Lipid polymers accumulate in the epidermis and mestome sheath cell walls during low temperature development of winter rye leaves

PROTOPLASMA ◽  
1985 ◽  
Vol 125 (1-2) ◽  
pp. 53-64 ◽  
Author(s):  
Marilyn Griffith ◽  
N. P. A. Huner ◽  
K. E. Espelie ◽  
P. E. Kolattukudy
Keyword(s):  
Low Temperature ◽  
Cell Walls ◽  
Winter Rye ◽  
Sheath Cell ◽  
Mestome Sheath ◽  
Temperature Development

scholarly journals Induction of Viable but Nonculturable Escherichia coli O157:H7 in the Phyllosphere of Lettuce: a Food Safety Risk Factor

2011 ◽  
Vol 77 (23) ◽  
pp. 8295-8302 ◽  
Author(s):  
Laura-Dorina Dinu ◽  
Susan Bach
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Low Temperature ◽  
Cell Density ◽  
Prolonged Storage ◽  
Potential Hazard ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
Content Type ◽  
E Coli

ABSTRACTEscherichia coliO157:H7 continues to be an important human pathogen and has been increasingly linked to food-borne illness associated with fresh produce, particularly leafy greens. The aim of this work was to investigate the fate ofE. coliO157:H7 on the phyllosphere of lettuce under low temperature and to evaluate the potential hazard of viable but nonculturable (VBNC) cells induced under such stressful conditions. First, we studied the survival of six bacterial strains following prolonged storage in water at low temperature (4°C) and selected two strains with different nonculturable responses for the construction ofE. coliO157:H7 Tn7gfptransformants in order to quantitatively assess the occurrence of human pathogens on the plant surface. Under a suboptimal growth temperature (16°C), bothE. coliO157:H7 strains maintained culturability on lettuce leaves, but under more stressful conditions (8°C), the bacterial populations evolved toward the VBNC state. The strain-dependent nonculturable response was more evident in the experiments with different inoculum doses (109and 106E. coliO157:H7 bacteria per g of leaf) when strain BRMSID 188 lost culturability after 15 days and strain ATCC 43895 lost culturability within 7 days, regardless of the inoculum dose. However, the number of cells entering the VBNC state in high-cell-density inoculum (approximately 55%) was lower than in low-cell-density inoculum (approximately 70%). We recorded the presence of verotoxin for 3 days in samples that contained a VBNC population of 4 to 5 log10cells but did not detect culturable cells. These findings indicate thatE. coliO157:H7 VBNC cells are induced on lettuce plants, and this may have implications regarding food safety.

Alterations in cell walls of winter wheat roots during low temperature acclimation

1998 ◽  
Vol 152 (4-5) ◽  
pp. 473-479 ◽  
Author(s):  
Alexey I. Zabotin ◽  
Tatyana S. Barisheva ◽  
Olga A. Zabotina ◽  
Irina A. Larskaya ◽  
Vera V. Lozovaya ◽  
...  
Keyword(s):  
Low Temperature ◽  
Winter Wheat ◽  
Cell Walls ◽  
Temperature Acclimation ◽  
Wheat Roots

scholarly journals Natural Fibre-Reinforced Biofoams

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Anne Bergeret ◽  
Jean Charles Benezet
Keyword(s):  
Mechanical Properties ◽  
Cellulose Fibre ◽  
Fibre Surface ◽  
Natural Fibre ◽  
Void Content ◽  
Blowing Agent ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Density Reduction ◽  
Screw Extrusion

Starches and polylactic acids (PLAs) represent the main biobased and biodegradable polymers with potential industrial availability in the next decades for “bio” foams applications. This paper investigates the improvement of their morphology and properties through processing and materials parameters. Starch foams were obtained by melt extrusion in which water is used as blowing agent. The incorporation of natural fibres (hemp, cellulose, cotton linter, sugarcane, coconut) in the starch foam induced a density reduction up to 33%, a decrease in water absorption, and an increase in mechanical properties according to the fibre content and nature. PLA foams were obtained through single-screw extrusion using of a chemical blowing agent that decomposed at the PLA melting temperature. A void content of 48% for PLA and 25% for cellulose fibre-reinforced PLA foams and an improvement in mechanical properties were achieved. The influence of a fibre surface treatment was investigated for both foams.

scholarly journals Foaming Behavior and Microcellular Morphologies of Incompatible SAN/CPE Blends with Supercritical Carbon Dioxide as a Physical Blowing Agent

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 89 ◽  
Author(s):  
Hai-Chen Zhang ◽  
Chun-Na Yu ◽  
Yong Liang ◽  
Gui-Xiang Lin ◽  
Cong Meng
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Pore Size ◽  
Cell Density ◽  
Average Pore Size ◽  
Average Pore ◽  
Chlorinated Polyethylene ◽  
Blowing Agent ◽  
Interconnected Pores ◽  
Supercritical Carbon

The foaming process and cellular morphologies of poly(styrene-co-acrylonitrile) (SAN)/chlorinated polyethylene (CPE) blends with supercritical carbon dioxide (scCO2) as a blowing agent were investigated in this study. As compared to pure SAN foam in the same batch, the foamed blends with various CPE elastomer content had smaller average pore size and larger cell density. This is probably related to the inhibition of bubble growth by elastomer, resulting in poor melt flowability and strong viscoelasticity, and the efficient bubble heterogeneous nucleation caused by numerous phase interfaces inside the incompletely compatible blend system. In addition, many tiny interconnected holes through the pore walls were formed to connect adjacent micropores in foamed blend samples. The formation mechanism of such interconnected pores is probably due to the fracture of stretched melt around the bubble from phase interfaces with weak interactions. These facts suggest an effective path to control pore size, cell density and even interconnected pores of blend foams depends on the compatibility of the blend system and difference in foamability of individual components in supercritical CO2.

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