Highly Regulatable Heat Conductance of Graphene–Sericin Hybrid for Responsive Textiles

2022 ◽  
pp. 2111121
Author(s):  
Xiaoping Liang ◽  
Aoran Fan ◽  
Zhen Li ◽  
Ning Wei ◽  
Wei Fan ◽  
...  
Keyword(s):  
Heat Conductance

Skinfolds and resting heat loss in cold air and water: temperature equivalence

1975 ◽  
Vol 39 (1) ◽  
pp. 93-102 ◽  
Author(s):  
R. M. Smith ◽  
J. M. Hanna
Keyword(s):  
Heat Transfer ◽  
Water Temperature ◽  
Heat Loss ◽  
Air Temperature ◽  
Indirect Calorimetry ◽  
Cold Water ◽  
Heat Conductance ◽  
Air Temperatures ◽  
Body Core ◽  
Male Subjects

Fourteen male subjects with unweighted mean skinfolds (MSF) of 10.23 mm underwent several 3-h exposures to cold water and air of similar velocities in order to compare by indirect calorimetry the rate of heat loss in water and air. Measurements of heat loss (excluding the head) at each air temperature (Ta = 25, 20, 10 degrees C) and water temperature (Tw = 29–33 degrees C) were used in a linear approximation of overall heat transfer from body core (Tre) to air or water. We found the lower critical air and water temperatures to fall as a negative linear function of MSF. The slope of these lines was not significantly different in air and water with a mean of minus 0.237 degrees C/mm MSF. Overall heat conductance was 3.34 times greater in water. However, this value was not fixed but varied as an inverse curvilinear function of MSF. Thus, equivalent water-air temperatures also varied as a function of MSF. Between limits of 100–250% of resting heat loss the followingrelationships between MSF and equivalent water-air temperatures were found (see article).

Tuning the thermoelectric properties of a single-molecule junction by mechanical stretching

2015 ◽  
Vol 17 (7) ◽  
pp. 5386-5392 ◽  
Author(s):  
Alberto Torres ◽  
Renato B. Pontes ◽  
Antônio J. R. da Silva ◽  
Adalberto Fazzio
Keyword(s):  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Single Molecule ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Heat Conductance ◽  
Molecule Junction ◽  
Electronic Heat ◽  
Single Molecule Junction ◽  
Mechanical Stretching

We theoretically investigate, as a function of the stretching, the behaviour of the Seebeck coefficient, the electronic heat conductance and the figure of merit of a molecule-based junction composed of a benzene-1,4-dithiolate (BDT) molecule coupled to Au(111) surfaces at room temperature.

Role of skin and of core temperatures in man's temperature regulation

1965 ◽  
Vol 20 (1) ◽  
pp. 31-36 ◽  
Author(s):  
C. H. Wyndham
Keyword(s):  
Skin Temperature ◽  
Rectal Temperature ◽  
Temperature Regulation ◽  
Passive Control ◽  
Sweat Rate ◽  
Heat Conductance ◽  
Response Characteristics ◽  
Highly Nonlinear ◽  
The Right ◽  
Skin Temperatures

The response characteristics have been studied of the curves relating heat conductance and sweat rate to change in rectal temperature at different levels of skin temperature, and vice versa. The increase in these responses with deviation in rectal temperature from the “neutral” setting is highly nonlinear; the neutral point and the curve shift to the right and the slope decreases with lowering of skin temperature and vice versa when it is raised. With further deviation of rectal temperature these responses reach maximum values, i.e., become “saturated.” All of these features are analogous to servomechanisms with negative feedback, giving sensitive and stable control. Control of these responses by skin temperature is more linear, characterizing passive control systems which are insensitive and less stable. Quantitatively, the effect at skin temperature of 26 C of 1 C rise in rectal temperature on heat conductance and sweat rate is 10 times greater than the same rise in skin temperature; at a neutral skin temperature of 33–34 C, a rise of 1 C in rectal temperature is 6–7 times greater; at a high skin temperature of 36 C, a rise in rectal temperature of 1 C is 4–5 times greater. relationship between heat conductance and a change in either rectal or skin temperatures; relationship between sweat rate and a change in either rectal or skin temperatures; response characteristics of curves relating heat conductance to change in either rectal or skin temperatures; response characteristics of curves relating sweat rate to change in either rectal or skin temperatures; assessment of the contribution of skin and rectal temperatures to man's temperature regulation Submitted on October 22, 1963

Simulation and Analysis of Metal Microfluidic Heatsinks

2006 ◽  
Author(s):  
Alireza Motieifar ◽  
C. Shafai ◽  
H. M. Soliman
Keyword(s):  
Thermal Resistance ◽  
Cross Section ◽  
Fluid Velocity ◽  
The Body ◽  
Silicon Substrates ◽  
Channel System ◽  
Heat Conductance ◽  
Fem Method ◽  
Rectangular Channels ◽  
Electroplated Copper

Microfluidic heatsinks are usually fabricated in silicon substrates using micromachining methods. Fabrication of microfluidic heatsinks in metals is captivating due to the potential of higher heat conductance of many metals compared to silicon. In this work, metallic microfluidic structures fabricated of copper, silicon, and nickel are simulated and analyzed using the FEM method. The parametric dependence of the overall thermal resistance on the heatsink material, fluid velocity, and channel geometry is examined. Their performance is compared based on the shape and size of the microchannels, their separating distance from each other, and the flow rate. Simulations were done using FEMLAB v.3.2 (Comsol Multyphysics). The length of the microchannels considered is 1cm. Their cross section is rectangular. Simulated heatsinks are covered with 50 μm of the same material as the body and the total area of the heat sink is 1cm × 1cm. Water is used as the coolant with an input temperature of 300 K. These simulations show that most of the thermal resistance in the heatsink occurs in the fluid region. For the constant and uniform input heating power of 100 W/cm2 the performance of the structure is studied at steady state with the fluid velocity varied from 1 to 14m/s. Finally, experimental fabrication of an electroplated copper micro-channel system with rectangular channels is shown.

Physiological reactions to heat of Bushmen and of unacclimatized and acclimatized Bantu

1964 ◽  
Vol 19 (5) ◽  
pp. 885-888 ◽  
Author(s):  
C. H. Wyndham ◽  
N. B. Strydom ◽  
J. S. Ward ◽  
J. F. Morrison ◽  
C. G. Williams ◽  
...  
Keyword(s):  
Physical Fitness ◽  
Ethnic Groups ◽  
Cold Exposure ◽  
Skinfold Thickness ◽  
Good Evidence ◽  
Heat Conductance ◽  
Heart Rates ◽  
Kalahari Desert ◽  
Cold Responses ◽  
Physiological Reactions

Bushmen in the Kalahari desert fulfill two criteria for acclimatization to heat. They exercise actively, in hunting, in relatively severe heat in midsummer. Compared with unacclimatized Bantu they have higher sweat rates per square meter and lower heart rates. However, rectal temperatures are not much lower than those of unacclimatized Bantu. River Bushmen present a paradoxical picture. In summer sweat rates are higher than in winter, but are not as high as desert Bushmen. Summer heart rates are, however, higher than in winter. Rectal temperatures in the two seasons are similar. The higher sweat rates in summer are good evidence of better acclimatization than in winter; the higher heart rates may be a reflection of differences in physical fitness in the two seasons. association of morphology and metabolism on cold exposure; cold responses of Bantu, Bushmen, and Caucasians; heat conductance and skinfold thickness in cold; metabolisms of Bantu, Bushmen, and Caucasians in cold; toe, finger, and rectal temperatures of different ethnic groups in cold Submitted on February 4, 1964

Heat transfer pathways between fetal lamb and ewe

1985 ◽  
Vol 59 (2) ◽  
pp. 634-638 ◽  
Author(s):  
R. D. Gilbert ◽  
H. Schroder ◽  
T. Kawamura ◽  
P. S. Dale ◽  
G. G. Power
Keyword(s):  
Amniotic Fluid ◽  
Heat Production ◽  
Temperature Response ◽  
Uterine Wall ◽  
Heat Fluxes ◽  
Fetal Skin ◽  
Heat Conductance ◽  
Umbilical Blood ◽  
Fetal Lamb ◽  
Umbilical Blood Flow

Heat produced by the fetus exists to the mother by one of two principal routes: by fetal-maternal exchange in the placenta or through the fetal skin to the amniotic fluid and uterine wall. We measured heat conductances along each pathway to estimate the fraction of total heat exiting each route. Thermistors were placed in the fetal aorta, two different sites in the amniotic fluid, and in a maternal artery. Five days after surgery we injected a total of 280 ml of ice-cold saline into the two separate amniotic fluid sites during a 45-s interval and measured the temperature response for the next hour. After one or two such injections the fetus was killed to cut off umbilical blood flow, and the experiment was repeated to measure the heat fluxes in the absence of placental heat exchange. Experimentally obtained temperature curves were compared with the predictions of a mathematical model. Heat conductances of the skin and uterine wall, as well as the fetal heat production, were estimated in the model using least-squares parameter optimization. In 10 fetal lambs, weighing 3.73 +/- 0.40 (SE) kg, total fetal heat production averaged 3.75 +/- 0.33 W X kg-1. The heat conductance of the uterine wall, 6.6 +/- 0.8 W X degrees C-1, was lower than that of the fetal skin, 10.2 +/- 1.0, and of the placenta, 25.7 +/- 2.9 W X degrees C-1, temperature gradient. We estimated that 84.5% of total fetal heat production exists by fetal-maternal exchange in the placenta with the remaining 15.5% exiting through the fetal skin.

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