Analysis of the Possibility of Using Geopolymers as a Matrix in Sprayed Concretes Used under Extreme Conditions

2012 ◽  
Vol 253-255 ◽  
pp. 576-582 ◽  
Author(s):  
Amos Dufka ◽  
Jana Kosíková ◽  
Lenka Mészárosová ◽  
Marek Liška
Keyword(s):  
High Temperatures ◽  
High Resistance ◽  
Fire Risk ◽  
Extreme Conditions ◽  
Extreme Temperatures ◽  
Considerable Potential

The article analyses the possibility of using geopolymers as a matrix of sprayed concretes intended for realisation of constructions in the environment with an increased fire risk. Thanks to their specific properties, geopolymers show a high resistance to extreme temperatures. Thus, using geopolymers as a matrix shows a considerable potential in the light of development of sprayed concretes resistant to high temperatures.

LOSS OF TLD SIGNAL DUE TO HIGH TEMPERATURE ENVIRONMENTAL CONDITIONS

2019 ◽  
Vol 187 (1) ◽  
pp. 17-20
Author(s):  
Andrew Villanueva ◽  
Braden Goddard
Keyword(s):  
Saudi Arabia ◽  
High Temperature ◽  
Elevated Temperature ◽  
United Arab Emirates ◽  
High Temperatures ◽  
Environmental Conditions ◽  
Statistical Difference ◽  
Light Output ◽  
Nuclear Industry ◽  
Extreme Temperatures

Abstract While it is known that temperatures above 100°C have an effect on the reported dose of a TLD, it is less widely known what the susceptibility is to temperatures below 100°C, temperatures humans could reasonably expect to be exposed to. With the expanding nuclear industry in climates with more extreme temperatures, (e.g. United Arab Emirates and Saudi Arabia) the effect on a TLD if left on a dashboard of a car need to be evaluated. This research experimentally determined the extent of this thermal susceptibility by testing a range of high temperatures, 40°C – 90°C. The experimental results found that there is a statistically significant reduction in TLD-100H (natLiF:Mg,Cu,P) light output for TLDs there were exposed to temperatures as low as 40°C for 8 hour durations and 50°C for 2 hour durations. There is statistical difference in TLD-100H light output for elevated temperature durations of 8 hours compared to 24 hours.

Recrystallisation Resistance of Extruded and Cold Rolled Aluminium Alloys with Additions of Hf, Sc and Zr

2006 ◽  
Vol 519-521 ◽  
pp. 525-530 ◽  
Author(s):  
Håkon Hallem ◽  
W.J. Rittel ◽  
Børge Forbord ◽  
Knut Marthinsen
Keyword(s):  
Cold Rolling ◽  
Structural Stability ◽  
High Temperatures ◽  
High Resistance ◽  
Aluminium Alloys ◽  
Cold Rolled

A high recrystallisation resistance is required in aluminium alloys intended for processing or use at temperatures between 450°C-600°C. Additions of Hf, Sc and Zr significantly improve the resistance to recrystallisation through the formation of Al3X-dispersoids (X=Hf,Sc,Zr), and in this work different concentrations and combinations of these elements were added to five aluminium alloys. The alloys were extruded, subjected to various degrees of cold rolling (0%-80%) and finally annealed at high temperatures in order to study the structural stability. All variants displayed a high resistance towards recrystallisation, but the best results were obtained in the alloy containing only Sc and Zr. In this alloy no signs of recrystallisation were observed even after 1 hour annealing of extruded and 80% cold rolled profiles at 600°C.

The Effect of extreme Temperatures on different Stages of Aëdes aegypti (L.)

1957 ◽  
Vol 48 (3) ◽  
pp. 593-599 ◽  
Author(s):  
Micha Bar-Zeev
Keyword(s):  
Aedes Aegypti ◽  
High Temperatures ◽  
Low Temperatures ◽  
Extreme Temperatures ◽  
Fourth Stage ◽  
Wetting And Drying ◽  
The Third ◽  
Adult Females ◽  
Cent Mortality

Earlier investigations of the effects of extreme temperatures on different stages of Aëdes aegypti (L.) were supplemented by studies of eggs, larvae and pupae in water, and of eggs and adult females in air at various relative humidities.Larvae of the same stage, young pupae (defined as those less than half-an-hour old) and old pupae (at least 36 hours old), in groups of 100, 25 and 25, respectively, were kept for various periods at low temperatures in incubators, or, at high temperatures in glass cylinders closed at their lower ends by cloth filters and inserted into water baths, and then transferred to water at 28°C. and the mortality determined from the numbers surviving 24 hr. later (in the case of larvae) or becoming adult (in the case of pupae). Eggs in batches of 1,000 were similarly treated, except that periods of 24 hr. in water at 28°C. with yeast as food added were alternated with 24-hr. periods of drying, and mortality determined on the number that hatched and survived to the third or fourth stage. Adult females (four days old) were exposed in groups of 50 for various periods in jars over appropriate solutions giving a complete range of relative humidities and kept at low, medium and high temperatures. Eggs in batches of 1,000 were subjected to the same treatments. The adults were kept at 28°C. and 60 per cent. R.H. before treatment and for 24 hr. afterwards and mortality then determined. Mortality of eggs was determined after alternate 24-hr. periods of wetting and drying at 28°C., as in the case of eggs treated in water. The results of all the experiments were expressed as the exposure-times required to give 50 per cent. mortality (T50), calculated from the observed data.

scholarly journals Microbial diversity of extreme habitats in human homes

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2376 ◽  
Author(s):  
Amy M. Savage ◽  
Justin Hills ◽  
Katherine Driscoll ◽  
Daniel J. Fergus ◽  
Amy M. Grunden ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
High Throughput ◽  
High Throughput Sequencing ◽  
Extreme Environments ◽  
Extreme Temperature ◽  
Hot Water ◽  
Extreme Conditions ◽  
Extreme Temperatures ◽  
Environmental Extremes ◽  
Extreme Habitats

High-throughput sequencing techniques have opened up the world of microbial diversity to scientists, and a flurry of studies in the most remote and extreme habitats on earth have begun to elucidate the key roles of microbes in ecosystems with extreme conditions. These same environmental extremes can also be found closer to humans, even in our homes. Here, we used high-throughput sequencing techniques to assess bacterial and archaeal diversity in the extreme environments inside human homes (e.g., dishwashers, hot water heaters, washing machine bleach reservoirs, etc.). We focused on habitats in the home with extreme temperature, pH, and chemical environmental conditions. We found a lower diversity of microbes in these extreme home environments compared to less extreme habitats in the home. However, we were nonetheless able to detect sequences from a relatively diverse array of bacteria and archaea. Habitats with extreme temperatures alone appeared to be able to support a greater diversity of microbes than habitats with extreme pH or extreme chemical environments alone. Microbial diversity was lowest when habitats had both extreme temperature and one of these other extremes. In habitats with both extreme temperatures and extreme pH, taxa with known associations with extreme conditions dominated. Our findings highlight the importance of examining interactive effects of multiple environmental extremes on microbial communities. Inasmuch as taxa from extreme environments can be both beneficial and harmful to humans, our findings also suggest future work to understand both the threats and opportunities posed by the life in these habitats.

scholarly journals Adaptations for Pressure and Temperature in Dihydrofolate Reductases

2021 ◽  
Vol 9 (8) ◽  
pp. 1706
Author(s):  
Ryan W. Penhallurick ◽  
Maya D. Durnal ◽  
Alliyah Harold ◽  
Toshiko Ichiye
Keyword(s):  
Hydrogen Bond ◽  
Dihydrofolate Reductase ◽  
Evolutionary History ◽  
Experimental Studies ◽  
Extreme Conditions ◽  
Extreme Temperatures ◽  
Dihydrofolate Reductases ◽  
History Of ◽  
Moritella Profunda ◽  
Dynamics Simulations

Enzymes from extremophilic microbes that live in extreme conditions are generally adapted so that they function under those conditions, although adaptations for extreme temperatures and pressures can be difficult to unravel. Previous studies have shown mutation of Asp27 in Escherichia coli dihydrofolate reductase (DHFR) to Glu27 in Moritella profunda (Mp). DHFR enhances activity at higher pressures, although this may be an adaptation for cold. Interestingly, MpDHFR unfolds at ~70 MPa, while Moritella yayanosii (My) was isolated at depths corresponding to ~110 MPa, indicating that MyDHFR might be adapted for higher pressures. Here, these adaptations are examined using molecular dynamics simulations of DHFR from different microbes in the context of not only experimental studies of activity and stability of the protein but also the evolutionary history of the microbe. Results suggest Tyr103 of MyDHFR may be an adaptation for high pressure since Cys103 in helix F of MpDHFR forms an intra-helix hydrogen bond with Ile99 while Tyr103 in helix F of MyDHFR forms a hydrogen bond with Leu78 in helix E. This suggests the hydrogen bond between helices F and E in MyDHFR might prevent distortion at higher pressures.

Volume Stability of Polymer-Silicate Based Materials Exposed to High Temperatures

2016 ◽  
Vol 714 ◽  
pp. 78-85
Author(s):  
Tomáš Melichar ◽  
Jiří Bydžovský ◽  
Ámos Dufka
Keyword(s):  
Thermal Stability ◽  
Composite Materials ◽  
High Temperatures ◽  
Cement Matrix ◽  
Extreme Temperatures ◽  
Silicate Matrix ◽  
Volume Stability ◽  
Positive Effect ◽  
Thermal Stability Of

This paper presents research into analysing the volume stability of composite materials based on a polymer-cement matrix. The attention was paid to the influence of extreme temperatures shocks. Materials of modified composition were gradually exposed to extreme temperatures and then cooled in furnaces. Cooling was carried out by two different ways, i.e. slow and rapid. Emphasis was placed on the aggregate type used – fine lightweight and dense. Also available materials from alternative resources which have positive effect on thermal stability of composites based on silicate matrix were considered.

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