Effects of ambient water vapor pressure and temperature on evaporative water loss inPeromyscus maniculatus andMus musculus

This paper presents the procedures and equations to be utilized for measurement of evaporative water loss (mw), by use of the dew-point hygrometer, in small animals exposed to air containing water vapor in an open-flow system. The system accounted accurately for the water evaporated from a bubble flask. In addition, hygrometric measurements of pulmocutaneous mw in pigeons (Columba livia, mean mass 0.31 kg) agreed closely with simultaneous gravimetric measurements, utilizing a desiccant in the sample stream, in a manner independently of air temperature (Ta, 20 or 40 degrees C), ambient water vapor pressure (PW, 4–16 10(2) Pa), or mw (5–66 mg-min-1). Evaporation in pigeons was independent of PW at 20 degrees C, but increased with decreasing PW at 40 degrees C, suggesting differences in ventilatory adjustments to changes in PW at the two temperatures.

Download Full-text

EFFECT OF WATER VAPOR ON THE FORMATION OF MODIFICATIONS

Canadian Journal of Chemistry ◽

10.1139/v65-346 ◽

1965 ◽

Vol 43 (9) ◽

pp. 2522-2529 ◽

Cited By ~ 21

Author(s):

R. A. Kuntze

Keyword(s):

Water Vapor ◽

Vapor Pressure ◽

Atmospheric Pressure ◽

Calcium Sulfate ◽

Water Vapor Pressure ◽

Exothermic Peak ◽

Vapor Pressures ◽

Ambient Water ◽

Rate Of Heating ◽

Calcium Sulfate Hemihydrate

The two recognized forms of calcium sulfate hemihydrate can be identified by the position of a relatively small exothermic peak in their differential thermograms. Hemihydrates prepared at various water vapor pressures up to 760 mm Hg were found to produce this exothermic peak in a position which is characteristic for the β-form. These results indicate that α-hemihydrate cannot be made at atmospheric pressure, as was previously suggested on the basis of heat solution measurements. The typical differential thermogram of α-hemihydrate is only obtained with material made by dehydration in solution or by autoclaving. The effect of ambient water vapor pressure on the position of the three peaks that occur in the differential thermogram of CaSO4•2H2O has also been studied. It was found that the incipient temperature of the second endothermic peak, corresponding to the transition of hemihydrate to soluble anhydrite, is displaced independent of the rate of heating from 145 °C to 187 °C with increasing water vapor pressures up to 760 mm Hg. This indicates that, for each temperature, a threshold water vapor pressure exists, above which soluble anhydrite cannot be formed.

Download Full-text

Physiological responses of a rodent to heliox reveal constancy of evaporative water loss under perturbing environmental conditions

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00051.2014 ◽

2014 ◽

Vol 307 (8) ◽

pp. R1042-R1048 ◽

Cited By ~ 5

Author(s):

Christine Elizabeth Cooper ◽

Philip Carew Withers

Keyword(s):

Water Vapor ◽

Metabolic Rate ◽

Environmental Conditions ◽

Water Loss ◽

Physiological Responses ◽

Ambient Air ◽

Minute Volume ◽

Evaporative Water Loss ◽

Evidence Based ◽

Evaporative Water

Total evaporative water loss of endotherms is assumed to be determined essentially by biophysics, at least at temperatures below thermoneutrality, with evaporative water loss determined by the water vapor deficit between the animal and the ambient air. We present here evidence, based on the first measurements of evaporative water loss for a small mammal in heliox, that mammals may have a previously unappreciated ability to maintain acute constancy of total evaporative water loss under perturbing environmental conditions. Thermoregulatory responses of ash-grey mice ( Pseudomys albocinereus) to heliox were as expected, with changes in metabolic rate, conductance, and respiratory ventilation consistent with maintaining constancy of body temperature under conditions of enhanced heat loss. However, evaporative water loss did not increase in heliox. This is despite our confirmation of the physical effect that heliox augments evaporation from nonliving surfaces, which should increase cutaneous water loss, and increases minute volume of live ash-grey mice in heliox to accommodate their elevated metabolic rate, which should increase respiratory water loss. Therefore, mice had not only a thermoregulatory but also a hygroregulatory response to heliox. We interpret these results as evidence that ash-grey mice can acutely control their evaporative water loss under perturbing environmental conditions and suggest that hygroregulation at and below thermoneutrality is an important aspect of the physiology of at least some small mammals.

Download Full-text

Dew-point hygrometry system for measurement of evaporative water loss in infants

Journal of Applied Physiology ◽

10.1152/jappl.1997.82.3.1008 ◽

1997 ◽

Vol 82 (3) ◽

pp. 1008-1017 ◽

Cited By ~ 5

Author(s):

Ronald L. Ariagno ◽

Steven F. Glotzbach ◽

Roger B. Baldwin ◽

David M. Rector ◽

Susan M. Bowley ◽

...

Keyword(s):

Water Loss ◽

Water Vapor Pressure ◽

Skin Surface ◽

Term Infant ◽

Evaporative Water Loss ◽

Dew Point ◽

Ambient Conditions ◽

Evaporative Water ◽

Clinical Investigations ◽

Vapor Pressure Gradient

Ariagno, Ronald L., Steven F. Glotzbach, Roger B. Baldwin, David M. Rector, Susan M. Bowley, and Robert J. Moffat.Dew-point hygrometry system for measurement of evaporative water loss in infants. J. Appl. Physiol.82(3): 1008–1017, 1997.—Evaporation of water from the skin is an important mechanism in thermal homeostasis. Resistance hygrometry, in which the water vapor pressure gradient above the skin surface is calculated, has been the measurement method of choice in the majority of pediatric investigations. However, resistance hygrometry is influenced by changes in ambient conditions such as relative humidity, surface temperature, and convection currents. We have developed a ventilated capsule method that minimized these potential sources of measurement error and that allowed second-by-second, long-term, continuous measurements of evaporative water loss in sleeping infants. Air with a controlled reference humidity (dew-point temperature = 0°C) is delivered to a small, lightweight skin capsule and mixed with the vapor on the surface of the skin. The dew point of the resulting mixture is measured by using a chilled mirror dew-point hygrometer. The system indicates leaks, is mobile, and is accurate within 2%, as determined by gravimetric calibration. Examples from a recording of a 13-wk-old full-term infant obtained by using the system give evaporative water loss rates of ∼0.02 mgH2O ⋅ cm−2 ⋅ min−1for normothermic baseline conditions and values up to 0.4 mgH2O ⋅ cm−2 ⋅ min−1 when the subject was being warmed. The system is effective for clinical investigations that require dynamic measurements of water loss.

Download Full-text

Effects of Water Vapor Density on Cutaneous Resistance to Evaporative Water Loss and Body Temperature in Green Tree Frogs (Hyla cinerea)

Physiological and Biochemical Zoology ◽

10.1086/673115 ◽

2013 ◽

Vol 86 (5) ◽

pp. 559-566 ◽

Cited By ~ 3

Author(s):

Mark L. Wygoda ◽

Constance A. Kersten

Keyword(s):

Water Vapor ◽

Body Temperature ◽

Water Loss ◽

Evaporative Water Loss ◽

Vapor Density ◽

Hyla Cinerea ◽

Evaporative Water ◽

Tree Frogs ◽

Cutaneous Resistance

Download Full-text

Physiologically derived critical evaporative coefficients for protective clothing ensembles

Journal of Applied Physiology ◽

10.1152/jappl.1987.63.3.1095 ◽

1987 ◽

Vol 63 (3) ◽

pp. 1095-1099 ◽

Cited By ~ 21

Author(s):

W. L. Kenney ◽

D. A. Lewis ◽

D. E. Hyde ◽

T. S. Dyksterhouse ◽

C. G. Armstrong ◽

...

Keyword(s):

Water Vapor ◽

Vapor Pressure ◽

Protective Clothing ◽

Water Vapor Pressure ◽

Radiant Heat ◽

Ambient Water ◽

External Work ◽

Metabolic Heat ◽

Physiological Approach ◽

Sweating Efficiency

When work is performed in heavy clothing, evaporation of sweat from the skin to the environment is limited by layers of wet clothing and air. The magnitude of decrement in evaporative cooling is a function of the clothing's resistance to permeation of water vapor. A physiological approach has been used to derive effective evaporative coefficients (he) which define this ability to evaporate sweat. We refined this approach by correcting the critical effective evaporative coefficient (K for sweating efficiency (Ke,eta') since only a portion of the sweat produced under such conditions is evaporated through the clothing. Six acclimated men and women walked at 30% maximal O2 consumption (150–200 W.m-2) at a constant dry bulb temperature as ambient water vapor pressure was systematically increased 1 Torr every 10 min. Critical pressure was defined as the partial pressure of water vapor (Pw) at which thermal balance could no longer be maintained and rectal temperature rose sharply. Each test was performed in various clothing ensembles ranging from cotton shirt and pants to “impermeable” suits. This approach was used to derive he by solving the general heat balance equation, M - W +/- (R + C) = w.he.(Psk - Pw), where M is metabolic heat production, W is external work, R is radiant heat exchange, C is convective heat transfer, w is skin wettedness, and Psk is water vapor pressure of fully wet skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Respiratory water loss in free-flying pigeons

Journal of Experimental Biology ◽

10.1242/jeb.204.21.3803 ◽

2001 ◽

Vol 204 (21) ◽

pp. 3803-3814 ◽

Cited By ~ 1

Author(s):

Gilead Michaeli ◽

Berry Pinshow

Keyword(s):

Water Vapor ◽

Air Temperature ◽

Water Loss ◽

Beat Frequency ◽

Ambient Air ◽

Columba Livia ◽

Evaporative Water Loss ◽

Diffusion Resistance ◽

Breathing Frequency ◽

Evaporative Water

SUMMARY We assessed respiratory and cutaneous water loss in trained tippler pigeons (Columba livia) both at rest and in free flight. In resting pigeons, exhaled air temperature Tex increased with ambient air temperature Ta (Tex=16.3+0.705Ta) between 15°C and 30°C, while tidal volume VT (VT=4.7±1.0 ml, mean ± s.d. at standard temperature and pressure dry) and breathing frequency fR (fR=0.46±0.06 breaths s–1) were independent of Ta. Respiratory water loss, RWL, was constant over the range of Ta (RWL=1.2±0.4 mg g–1 h–1) used. In flying pigeons, Tex increased with Ta (Tex=25.8+0.34Ta), while fR was independent of Ta (fR=5.6±1.4 breaths s–1) between 8.8°C and 27°C. Breathing frequency varied intermittently between 2 and 8 breaths s–1 during flight and was not always synchronized with wing-beat frequency. RWL was independent of air temperature (RWL=9.2±2.9 mg g–1 h–1), but decreased with increasing inspired air water vapor density (ρin) (RWL=12.5–0.362ρin), whereas cutaneous water loss, CWL, increased with air temperature (CWL=10.122+0.898Ta), but was independent of ρin. RWL was 25.7–32.2 %, while CWL was 67.8–74.3 % of the total evaporative water loss. The data indicate that pigeons have more efficient countercurrent heat exchange in their anterior respiratory passages when at rest than in flight, allowing them to recover more water at rest at lower air temperatures. When evaporative water loss increases in flight, especially at high Ta, the major component is cutaneous rather than respiratory, possibly brought about by reducing the skin water vapor diffusion resistance. Because of the tight restrictions imposed by gas exchange in flight, the amount of water potentially lost through respiration is limited.

Download Full-text