The problem of heat exposure to a closed hydrate-saturated area of a porous stratum

2019 ◽  
Author(s):  
N. G. Musakaev ◽  
S. L. Borodin ◽  
D. S. Belskikh
Keyword(s):  
Heat Exposure ◽  
Porous Stratum

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Effect of prolactin inhibition under heat exposure on water intake and excretion of urine, sodium and potassium in bulls

1980 ◽  
Vol 94 (3) ◽  
pp. 315-320 ◽  
Author(s):  
D. Schams ◽  
E. Stephan ◽  
R. D. Hooley
Keyword(s):  
Water Intake ◽  
Heat Exposure ◽  
Physiological Role ◽  
Treated Group ◽  
Serum Prolactin ◽  
Control Value ◽  
Light Regimen ◽  
Group I ◽  
Urinary Potassium ◽  
Group Ii

Abstract. Six Holstein bulls were housed in a climate-chamber under constant light regimen and after two weeks of preconditioning at 15°C, 60% relative humidity RH (day) and 12°C, 60% RH (night) were subjected to two weeks of heat exposure. This involved one week at 30°C and 60% RH (day) and 25°C and 60% RH (night) and a further week at 35°C, 60% RH (day) and 30°C, 60% RH (night). Three bulls were untreated (group I) and 3 bulls were treated (group II) just before and during heat exposure with a prolactin inhibitor to study the possible physiological role of prolactin on the regulation of water, potassium and sodium. Serum prolactin levels increased significantly (P < 0.01) in group I from the control value of 6 ng/ml to 33 and 44 ng/ml when the ambient temperature was increased (weeks 3 and 4) and then decreased to 21 and 12 ng/ml after reduction in temperature during weeks 5 and 6, respectively. For group II prolactin values decreased under the treatment with the prolactin inhibitor to 0.5 ng/ml and remained at this level throughout the experiment. GH levels were unaffected by heat treatment or by treatment with prolactin inhibitor. There were no differences between groups I and II in respiratory rate, pulse rate and rectal temperature. Water intake increased in both groups under heat exposure but decreased significantly afterwards only in group II. Differences in urinary excretion volume and blood serum osmolality were not significant. Urinary potassium and sodium excretion were unchanged in group II but increased with heat exposure in group I. During heat exposure 2 bulls of group II lost weight despite maintaining food intake.

A Practical Ultrasonic Inspection Method for Detecting and Characterising Defects Found Within Composite Repairs

2018 ◽  
Author(s):  
J Downing ◽  
A Hook
Keyword(s):  
Wall Thickness ◽  
Steel Substrate ◽  
Ultrasonic Method ◽  
Ultrasonic Inspection ◽  
Heat Exposure ◽  
Matrix Cracking ◽  
Ultrasonic Technique ◽  
Inspection Method ◽  
Composite Repairs ◽  
Layered Matrix

Two steel substrate test panels were developed to represent common plate thicknesses found on naval vessels and scanned using the Babcock developed ultrasonic technique. One sample comprised of a series of slotted surface breaking flaws of varying widths and through thicknesses to represent fracturing/cracking. The inspection method detected simulated cracking to a depth of 2mm and 0.5mm in width. The second sample included numerous loss of wall thickness areas of varying diameters and through thicknesses, with the smallest detectable loss of wall thickness being 0.1mm at a 15mm diameter. After proving confidence in detection, there was a need to characterise flaws to provide support and ascertain a repair action. Samples were produced that were subjected to either impact or heat exposure to induce realistic representative damage. The practical ultrasonic method was successfully used to independently characterise between the samples, with induced de-laminations caused by blisters, and multi layered matrix cracking caused by varying levels of projectile impacts, due to their unique morphology.

Vulnerability of Drop Ceilings in Roadway Tunnels to Fire-Induced Damage

2021 ◽  
pp. 036119812110266
Author(s):  
Ziyan Ouyang ◽  
Qi Guo ◽  
Spencer E. Quiel ◽  
Clay J. Naito
Keyword(s):  
Fire Hazard ◽  
Heat Exposure ◽  
Element Analysis ◽  
Passive Protection ◽  
Cooling Period ◽  
Flexural Response ◽  
Standard Fire ◽  
Significant Damage ◽  
The Finite Element Analysis ◽  
Simultaneous Loss

Roadway tunnels often include a reinforced concrete drop ceiling that is hung from the liner to create a plenum that facilitates ventilation and houses utilities. Drop ceiling panels are lightweight compared with the much thicker tunnel liner and can experience significant damage from a fire on the roadway below. This paper examines the flexural response of drop ceiling panels in two representative tunnels to standard fire curves as well as several realistic fires due to vehicular accidents. Standard fire demands as per the Rijkswaterstaat and ASTM E1529 fire curves are uniformly applied to the ceiling panels, and heat exposure contours for typical vehicle fires with heat release rates of 30, 100, and 200 MW are generated from the software CFAST. The finite element analysis software SAFIR is used to evaluate the thermo-mechanical behavior of the ceiling panels when subjected to various thermal demands from the fire below. The analysis results indicate that drop ceiling panels are highly vulnerable to fire-induced damage and potential collapse both during a fire’s active heating phase (from simultaneous loss of capacity and restraint of thermal expansion) and during the subsequent cooling period (from tension that develops when the permanently deformed panel thermally retracts). The potential for fire-induced damage or collapse of the drop ceiling panels can be mitigated by reducing the fire hazard, removing the drop ceiling, or enhancing the fire resistance of the panels via the application of passive protection or structural hardening.

Climate change and infrastructure risk: Indoor heat exposure during a concurrent heat wave and blackout event in Phoenix, Arizona

Urban Climate ◽  
2021 ◽  
Vol 36 ◽  
pp. 100787
Author(s):  
Brian Stone ◽  
Evan Mallen ◽  
Mayuri Rajput ◽  
Ashley Broadbent ◽  
E. Scott Krayenhoff ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Wave ◽  
Heat Exposure

Effect of K-wire Reuse and Drill Mode on Heat Generation in Bone

Hand ◽  
2021 ◽  
pp. 155894472110031
Author(s):  
Muturi G. Muriuki ◽  
Arun K. Reddy ◽  
Alex Tauchen ◽  
Robert M. Havey ◽  
Avinash G. Patwardhan ◽  
...  
Keyword(s):  
Cell Death ◽  
Cortical Bone ◽  
Heat Generation ◽  
Kirschner Wire ◽  
Heat Exposure ◽  
Critical Temperatures ◽  
Rotary Drilling ◽  
External Cooling ◽  
K Wires ◽  
Oscillating Mode

Background We examined the effect of Kirschner wire (K-wire) reuse and use of oscillating mode on heat generation within cortical bone. Methods Two trocar-tipped K-wires were drilled through the diaphysis of each of 30 human metacarpals and phalanges: one K-wire was inserted in rotary mode and another in oscillating mode. Each wire was reused once. Thermocouples placed within the dorsal and volar bone adjacent to the K-wire drill path measured temperatures throughout each test. Results Peak cortex temperatures were 25°C to 164°C. Rotary drilling achieves peak temperatures quicker (31 ± 78 seconds vs 44 ± 78 seconds, P = .19) than oscillating drilling, but insertion time is also less, resulting in lower overall heat exposure. This effect is also seen when the K-wire is reused (34 ± 70 seconds vs 41 ± 85 seconds, P = .4). The length of time that cortical bone was exposed to critical temperatures (47°C or more) was significantly higher when a wire was reused (36 ± 72 seconds vs 43 ± 82 seconds, P = .008). Peak temperatures greater than 70°C (a temperature associated with instantaneous cell death) were observed on many occasions. Conclusions Overall heat exposure may be higher if a K-wire is reused or inserted in oscillating mode. In the absence of external cooling, K-wire insertion into cortical bone can easily expose bone to temperatures that exceed 70°C and may increase the risk of osteonecrosis.

Review of heat exposure equipment and in-situ characterisation techniques for intumescent coatings

2020 ◽  
pp. 103264
Author(s):  
Jochen A.H. Dreyer ◽  
Claus Erik Weinell ◽  
Kim Dam-Johansen ◽  
Søren Kiil
Keyword(s):  
Heat Exposure ◽  
Intumescent Coatings ◽  
Characterisation Techniques

scholarly journals The Cardiometabolic Health Benefits of Sauna Exposure in Individuals with High-Stress Occupations. A Mechanistic Review

2021 ◽  
Vol 18 (3) ◽  
pp. 1105
Author(s):  
Kaemmer N. Henderson ◽  
Lauren G. Killen ◽  
Eric K. O’Neal ◽  
Hunter S. Waldman
Keyword(s):  
Multiple Stressors ◽  
Heat Exposure ◽  
High Stress ◽  
The United States ◽  
Cellular Level ◽  
Cardiometabolic Health ◽  
Low Grade ◽  
Current Standard ◽  
The Metabolic Syndrome ◽  
Sauna Bathing

Components of the metabolic syndrome (i.e., hypertension, insulin resistance, obesity, atherosclerosis) are a leading cause of death in the United States and result in low-grade chronic inflammation, excessive oxidative stress, and the eventual development of cardiometabolic diseases (CMD). High-stress occupations (HSO: firefighters, police, military personnel, first responders, etc.) increase the risk of developing CMD because they expose individuals to chronic and multiple stressors (i.e., sleep deprivation, poor nutrition habits, lack of physical activity, psychological stress). Interestingly, heat exposure and, more specifically, sauna bathing have been shown to improve multiple markers of CMD, potentially acting as hormetic stressors, at the cellular level and in the whole organism. Therefore, sauna bathing might be a practical and alternative intervention for disease prevention for individuals with HSO. The purpose of this review is to detail the mechanisms and pathways involved in the response to both acute and chronic sauna bathing and collectively present sauna bathing as a potential treatment, in addition to current standard of care, for mitigating CMD to both clinicians and individuals serving in HSO.

scholarly journals High-Resolution Modelling of Thermal Exposure during a Hot Spell: A Case Study Using PALM-4U in Prague, Czech Republic

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 175
Author(s):  
Jan Geletič ◽  
Michal Lehnert ◽  
Pavel Krč ◽  
Jaroslav Resler ◽  
Eric Scott Krayenhoff
Keyword(s):  
Czech Republic ◽  
Urban Areas ◽  
Heat Exposure ◽  
Thermal Exposure ◽  
Urban Environments ◽  
Cooling Effect ◽  
Spatiotemporal Variability ◽  
Climate Index ◽  
Street Canyons ◽  
General Terms

The modelling of thermal exposure in outdoor urban environments is a highly topical challenge in modern climate research. This paper presents the results derived from a new micrometeorological model that employs an integrated biometeorology module to model Universal Thermal Climate Index (UTCI). This is PALM-4U, which includes an integrated human body-shape parameterization, deployed herein for a pilot domain in Prague, Czech Republic. The results highlight the key role of radiation in the spatiotemporal variability of thermal exposure in moderate-climate urban areas during summer days in terms of the way in which this directly affects thermal comfort through radiant temperature and indirectly through the complexity of turbulence in street canyons. The model simulations suggest that the highest thermal exposure may be expected within street canyons near the irradiated north sides of east–west streets and near streets oriented north–south. Heat exposure in streets increases in proximity to buildings with reflective paints. The lowest heat exposure during the day may be anticipated in tree-shaded courtyards. The cooling effect of trees may range from 4 °C to 9 °C in UTCI, and the cooling effect of grass in comparison with artificial paved surfaces in open public places may be from 2 °C to 5 °C UTCI. In general terms, this study illustrates that the PALM modelling system provides a new perspective on the spatiotemporal differentiation of thermal exposure at the pedestrian level; it may therefore contribute to more climate-sensitive urban planning.

scholarly journals A novel mouse model of heatstroke accounting for ambient temperature and relative humidity

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Kazuyuki Miyamoto ◽  
Keisuke Suzuki ◽  
Hirokazu Ohtaki ◽  
Motoyasu Nakamura ◽  
Hiroki Yamaga ◽  
...  
Keyword(s):  
Gene Expression ◽  
Body Temperature ◽  
Relative Humidity ◽  
Ambient Temperature ◽  
Core Body Temperature ◽  
Heat Exposure ◽  
Organ Damage ◽  
Core Body ◽  
The Impact ◽  
Treatment Water

Abstract Background Heatstroke is associated with exposure to high ambient temperature (AT) and relative humidity (RH), and an increased risk of organ damage or death. Previously proposed animal models of heatstroke disregard the impact of RH. Therefore, we aimed to establish and validate an animal model of heatstroke considering RH. To validate our model, we also examined the effect of hydration and investigated gene expression of cotransporter proteins in the intestinal membranes after heat exposure. Methods Mildly dehydrated adult male C57/BL6J mice were subjected to three AT conditions (37 °C, 41 °C, or 43 °C) at RH > 99% and monitored with WetBulb globe temperature (WBGT) for 1 h. The survival rate, body weight, core body temperature, blood parameters, and histologically confirmed tissue damage were evaluated to establish a mouse heatstroke model. Then, the mice received no treatment, water, or oral rehydration solution (ORS) before and after heat exposure; subsequent organ damage was compared using our model. Thereafter, we investigated cotransporter protein gene expressions in the intestinal membranes of mice that received no treatment, water, or ORS. Results The survival rates of mice exposed to ATs of 37 °C, 41 °C, and 43 °C were 100%, 83.3%, and 0%, respectively. From this result, we excluded AT43. Mice in the AT 41 °C group appeared to be more dehydrated than those in the AT 37 °C group. WBGT in the AT 41 °C group was > 44 °C; core body temperature in this group reached 41.3 ± 0.08 °C during heat exposure and decreased to 34.0 ± 0.18 °C, returning to baseline after 8 h which showed a biphasic thermal dysregulation response. The AT 41 °C group presented with greater hepatic, renal, and musculoskeletal damage than did the other groups. The impact of ORS on recovery was greater than that of water or no treatment. The administration of ORS with heat exposure increased cotransporter gene expression in the intestines and reduced heatstroke-related damage. Conclusions We developed a novel mouse heatstroke model that considered AT and RH. We found that ORS administration improved inadequate circulation and reduced tissue injury by increasing cotransporter gene expression in the intestines.

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