Diffusion of water vapor through human skin in hot environment and with application of atropine

1959 ◽  
Vol 14 (2) ◽  
pp. 276-278 ◽  
Author(s):  
Konrad J. K. Buettner ◽  
Frederick F. Holmes
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Human Skin ◽  
Liquid Water ◽  
Water Loss ◽  
Diffusion Resistance ◽  
Vapor Transfer ◽  
Hot Environment ◽  
Human Forearm ◽  
Very High

At room temperatures between 20° and 40°C, vapor transfer through skin of human forearm was tested with four small heated bottles containing air of humidities ranging from 2 to 100% relative humidity. Exposure times ranging from 30 to 120 minutes had no influence on results. Water loss or gain of skin were observed for the different bottles. At very high humidities, liquid water deposit on the skin was measured by weighing a blotter. Skin vapor loss decreases systematically when bottle moisture increases. This increase is enhanced at room temperatures above 24℃, where total loss into a dry bottle increases more than fivefold. This increase seems only partially caused by sweat and partially by a decrease of the skin diffusion resistance. Tourniquet and locally applied atropine did not affect vapor transfer in a cool room. In a hot room, the tourniquet lowered the vapor loss by only 20%, whereas atropine drastically curtailed vapor loss. Submitted on August 25, 1958

Diffusion of water vapor through small areas of human skin in normal environment

1959 ◽  
Vol 14 (2) ◽  
pp. 269-275 ◽  
Author(s):  
Konrad J. K. Buettner
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Vapor Pressure ◽  
Skin Temperature ◽  
Horny Layer ◽  
Small Areas ◽  
Vapor Transfer ◽  
Normal Environment ◽  
Made In ◽  
Frequency Curves

Four small skin areas of the forearm were exposed concurrently to four small bottles at skin temperature. The bottles contained certain wet salts which condition the local vapor pressure. The vapor transfer between skin and bottles resulted in a measurable weight change of the bottles. One thousand tests on 250 people were made in a comfortable room. Below a critical humidity, vapor left the skin; above this ‘neutral relative humidity’ (NRH) the skin gained vapor. A small portion of this skin intake is used to moisten the horny layer. Correcting for this, the average of all tests is NRH = 86%. Frequency curves show two significant maxima besides that around 86%, viz. one around a NRH of 60–70%, generally concurrent with edema, and one above 90% NRH, usually observed on sweating skin. Length of exposure (30 min.-8 hr.), season and skin temperature (excluding sweating) have no recognizable influence on NRH. Submitted on August 25, 1958

Water-Resistance of Nanofiber Textiles

2017 ◽  
Vol 731 ◽  
pp. 55-59
Author(s):  
Martin Černohorský ◽  
Michal Havrlík
Keyword(s):  
Contact Angle ◽  
Water Vapor ◽  
Liquid Water ◽  
Water Resistance ◽  
Diffusion Resistance ◽  
European Standard ◽  
Material Basis ◽  
Nanofiber Textile ◽  
Resistance To Penetration

This work deals with the determination of basic waterproofing properties of nanofiber textiles with basis weights of up to 30 g/m2. Samples used in this experiment were made from nanofiber textiles based on two polymers – PVDF and PUR. Each polymer was prepared in three basis weights. All samples were not treated prior to testing. One of the key properties was the contact angle of water and the resistance to penetration of liquid water. Water-resistance of nanofiber textiles was tested according to the harmonized European standard EN 13859-1., Underlays for discontinuous roofing in pitched roof constructions are tested according to this standard. In the position of underlays there has to be some layer with low diffusion resistance of water vapor and relatively high waterproofing. We suppose such properties of nanofiber textiles. Testing of the two groups of material basis shows correlation between the contact angle and water-resistance of the nanofiber textile.

scholarly journals Characterization and Corrections of Relative Humidity Measurement from Meteomodem M10 Radiosondes at Midlatitude Stations

2020 ◽  
Vol 37 (5) ◽  
pp. 857-871
Author(s):  
Jean-Charles Dupont ◽  
Martial Haeffelin ◽  
Jordi Badosa ◽  
Gaelle Clain ◽  
Christophe Raux ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Humidity Sensor ◽  
Global Climate ◽  
Time Lag ◽  
Capacitive Sensor ◽  
Cold Temperatures ◽  
Humidity Measurements ◽  
Main Effects ◽  
Very High

AbstractMeasurement of water vapor or humidity in the atmosphere is fundamental for many applications. Relative humidity measurements with a capacitive sensor in radiosondes are affected by several factors that need to be assessed and corrected. This work aims to address corrections for the main effects for the Meteomodem M10 radiosonde as a step to meet the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) requirements. The considered corrections are 1) the calibration correction; 2) a slow regime due to the slow diffusion of molecules through the sensor, especially at very high and very low relative humidity conditions; 3) the relative humidity sensor dependence on the gradient of temperature; and 4) the time lag at cold temperatures, which affects measurements in regions of strong relative humidity gradients. These corrections were tested for 26 nighttime and 25 daytime radiosondes in two midlatitude locations for which both Meteomodem M10 and Vaisala RS92 measurements were available. The results show that, after correcting for the four effects, M10 relative humidity measurements are, on average, consistent with the Vaisala RS92 relative humidity values within 2% RH at all altitudes for the nighttime launches (against 6% RH before the correction) and within 5% RH at all altitudes for the daytime launches (against 9% RH before the correction).

WATER VAPOR TRANSPORT IN PLASTERS CONTAINING SUPERABSORBENT POLYMERS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jan Fořt ◽  
Martin Mildner ◽  
Petr Hotěk ◽  
Robert Černý
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Transport Properties ◽  
Building Design ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Diffusion Resistance ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion

A proper characterization of material properties represents an important step towards an efficient building design. Considering the present issues in the construction sector, moisture loads pose a risk not only to increased material deterioration but also to the health of building inhabitants. In this paper, modified plaster mixtures with superabsorbent admixture are designed in order to improve passive moderation of finishing layers against varying humidity conditions. The relationship between the amount of applied superabsorbent admixture and resulting water vapor transport properties is identified and the influence of temperature on water vapor transport is analyzed. The steady-state cup method is used for the determination of water vapor transport properties, namely the water vapor diffusion permeability, water vapor diffusion coefficient and water vapor diffusion resistance factor. The obtained data show temperature as a very significant factor affecting water vapor transport in the analyzed plasters. Considering the dry-cup method arrangement, relative humidity probes should be used for monitoring relative humidity under the sealed sample for a sufficiently precise determination of water vapor pressure gradient.

scholarly journals Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities

2014 ◽  
Vol 14 (4) ◽  
pp. 2071-2104 ◽  
Author(s):  
C. Marcolli
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Clay Minerals ◽  
Liquid Water ◽  
Vapor Deposition ◽  
Ice Nucleation ◽  
Classical View ◽  
Immersion Freezing ◽  
Kelvin Effect ◽  
Mcm 41

Abstract. Heterogeneous ice nucleation is an important mechanism for the glaciation of mixed phase clouds and may also be relevant for cloud formation and dehydration at the cirrus cloud level. It is thought to proceed through different mechanisms, namely contact, condensation, immersion and deposition nucleation. Conceptually, deposition nucleation is the only pathway that does not involve liquid water, but occurs by direct water vapor deposition onto a surface. This study challenges this classical view by putting forward the hypothesis that what is called deposition nucleation is in fact pore condensation and freezing (PCF) occurring in voids and cavities that may form between aggregated primary particles and host water at relative humidity RHw < 100% because of the inverse Kelvin effect. Homogeneous ice nucleation is expected to occur below 235 K when at least one pore is filled with water. Ice nucleation in pores may also happen in immersion mode but with a lower probability because it requires at least one active site in a water filled pore. Therefore a significant enhancement in ice nucleation efficiency is expected when temperature falls below 235 K. For a deposition nucleation process from water vapor no discontinuous change in ice nucleation efficiency should occur at T = 235 K because no liquid water is involved in this process. Studies on freezing in confinement carried out on mesoporous silica materials such as SBA-15, SBA-16, MCM-41, zeolites and KIT have shown that homogeneous ice nucleation occurs abruptly at T = 230–235 K in pores with diameters (D) of 3.5–4 nm or larger but only gradually at T = 210–230 K in pores with D = 2.5–3.5 nm. Pore analysis of clay minerals shows that kaolinites exhibit pore structures with pore diameters (Dp) of 20–50 nm. The mesoporosity of illites and montmorillonites is characterized by pores with Dp = 2–5 nm. The number and size of pores is distinctly increased in acid treated montmorillonites like K10. Water adsorption isotherms of MCM-41 show that pores with Dp = 3.5–4 nm fill with water at RHw = 56–60% in accordance with an inverse Kelvin effect. Water in such pores should freeze homogeneously for T < 235 K even before relative humidity with respect to ice (RHi) reaches ice saturation. Ice crystal growth by water vapor deposition from the gas phase is therefore expected to set in as soon as RHi > 100%. Pores with D > 7.5 nm fill with water at RHi > 100% for T < 235 K and are likely to freeze homogeneously as soon as they are filled with water. Given the pore structure of clay minerals, PCF should be highly efficient for T < 235 K and may occur at T > 235 K in particles that exhibit active sites for immersion freezing within pores. Most ice nucleation studies on clay minerals and mineral dusts indeed show a strong increase in ice nucleation efficiency when temperature is decreased below 235 K in accordance with PCF and are not explicable by the classical view of deposition nucleation. PCF is probably also the prevailing ice nucleation mechanism below water saturation for glassy, soot, and volcanic ash aerosols. No case could be identified that gives clear evidence of ice nucleation by water vapor deposition onto a solid surface.

scholarly journals Water vapor transport to a semi-infinite material with simultaneous varying surface relative humidity and temperature

2020 ◽  
Vol 172 ◽  
pp. 04005
Author(s):  
Carl-Eric Hagentoft
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Water Vapor Transport ◽  
Time Varying ◽  
Temperature Changes ◽  
Vapor Transfer ◽  
Moisture Balance ◽  
Sinusoidal Functions ◽  
The One ◽  
Water Vapor Transfer

The water vapor transfer between the indoor air and hygroscopic finishing materials is of importance for the moisture balance of the room. Most protocols for determining the effect are based on isothermal conditions and cycling relative humidity in the form of square wave or sinusoidal functions. A new analytical solution for a material exposed to a both time varying surface relative humidity and temperature is presented in the paper. The time varying temperature inside the material is assumed to follow the surface temperature throughout the material layer since the reaction time for temperature changes in a reasonable thin surface material is rather short compared with the one for moisture changes. The semi-infinite approach is justified by the fact that the penetration depth for moisture variations are very limited for diurnal variations. The analytical approach and solution are presented in the paper

Components of apparent soil thermal conductivity measured by the heat pulse method

2021 ◽  
Author(s):  
Sen Lu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Water Vapor ◽  
Water Content ◽  
Liquid Water ◽  
Sandy Loam ◽  
Sensible Heat ◽  
Soil Thermal Conductivity ◽  
Vapor Diffusion ◽  
Vapor Transfer

&lt;p&gt;Knowledge on the components of apparent soil thermal conductivity (&amp;#955;) across various water contents (&amp;#952;) and temperatures is important to accurately understand soil heat transfer mechanisms. In this study, soil thermal conductivity was measured for sandy loam and silty clay soils at various temperatures and air pressures using a transient method. Four components of &amp;#955;, namely, heat conduction, latent heat transfer by water vapor diffusion, sensible heat transfer by liquid water, and sensible heat transfer by water vapor diffusion were quantified. Results showed that in uniform soils, the magnitudes of sensible heat transfers by liquid water and water vapor were negligible during these transient measurements. The contribution of latent heat transfer through vapor diffusion to total heat transfer increased as temperature increased, and the peak value occurred at an intermediate water content. The water content at which the maximum vapor diffusion occurred varied with soil texture. In addition to the four calculated components, a significant residual contribution to &amp;#955; caused by an unidentified vapor transfer mechanism was observed between 3.5&amp;#176;C and 81&amp;#176;C. For example, calculations indicated that approximately 66% of the sandy loam &amp;#955; at &amp;#952;=0.11 m&lt;sup&gt;3&lt;/sup&gt; m&lt;sup&gt;&amp;#8722;3&lt;/sup&gt; was caused by an unidentified vapor transfer mechanism at 81&amp;#176;C. This extra contribution by vapor transfer could be explained either as enhanced vapor diffusion or by an advection mechanism. Further investigation is needed to clarify whether enhanced diffusion or advection is occurring in unsaturated soils.&amp;#160;&lt;/p&gt;

Respiratory water loss in free-flying pigeons

2001 ◽  
Vol 204 (21) ◽  
pp. 3803-3814 ◽  
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.

Untersuchungen zum Diffusionswiderstand von Holzwerkstoffen | Diffusion resistance of timber materials

2005 ◽  
Vol 156 (3-4) ◽  
pp. 100-103
Author(s):  
Rudolf Popper ◽  
Peter Niemz ◽  
Gerhild Eberle
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Middle Lamella ◽  
Solid Wood ◽  
Diffusion Resistance ◽  
Water Vapour Diffusion ◽  
Wood Panels ◽  
Vapour Diffusion ◽  
Wet Climate ◽  
Panel Thickness

The water vapour diffusion resistance of timber materials were tested in a wet climate (relative humidity ranging from 100%to 65% at 20 °C) and in a dry climate (relative humidity ranging from 0% to 65% and from 0% to 35% at 20 °c) with variation by relative humidity and vapour pressure gradient. The diffusion resistance of multilayer solid wood panels lies under or within the range of the solid wood (spruce), tending even to a lower range. This can be attributed to the loosely inserted middle lamella of the used solid wood panels, which were not correctly glued by the manufacturer. The diffusion resistance of the solid wood panels increases with decreasing moisture content and decreasing panel thickness, as well as with increasing water vapour gradient from 818 to 1520 Pa. There were clear differences between the tested timber materials. The diffusion resistance of particle composites is strongly dependent on the specific gravity. Due to laminar particles OSBs(Oriented Strand Boards) have a larger diffusion resistance than chipboards. The water vapour diffusion resistance of OSBs lies within the range of plywood.

scholarly journals HGPT2: An ERA5-Based Global Model to Estimate Relative Humidity

2021 ◽  
Vol 13 (11) ◽  
pp. 2179
Author(s):  
Pedro Mateus ◽  
Virgílio B. Mendes ◽  
Sandra M. Plecha
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Real Time ◽  
Prediction Models ◽  
Weather Prediction ◽  
Precipitable Water ◽  
Precipitable Water Vapor ◽  
Global Navigation Satellite Systems ◽  
International Gnss Service ◽  
Weighted Mean Temperature

The neutral atmospheric delay is one of the major error sources in Space Geodesy techniques such as Global Navigation Satellite Systems (GNSS), and its modeling for high accuracy applications can be challenging. Improving the modeling of the atmospheric delays (hydrostatic and non-hydrostatic) also leads to a more accurate and precise precipitable water vapor estimation (PWV), mostly in real-time applications, where models play an important role, since numerical weather prediction models cannot be used for real-time processing or forecasting. This study developed an improved version of the Hourly Global Pressure and Temperature (HGPT) model, the HGPT2. It is based on 20 years of ERA5 reanalysis data at full spatial (0.25° × 0.25°) and temporal resolution (1-h). Apart from surface air temperature, surface pressure, zenith hydrostatic delay, and weighted mean temperature, the updated model also provides information regarding the relative humidity, zenith non-hydrostatic delay, and precipitable water vapor. The HGPT2 is based on the time-segmentation concept and uses the annual, semi-annual, and quarterly periodicities to calculate the relative humidity anywhere on the Earth’s surface. Data from 282 moisture sensors located close to GNSS stations during 1 year (2020) were used to assess the model coefficients. The HGPT2 meteorological parameters were used to process 35 GNSS sites belonging to the International GNSS Service (IGS) using the GAMIT/GLOBK software package. Results show a decreased root-mean-square error (RMSE) and bias values relative to the most used zenith delay models, with a significant impact on the height component. The HGPT2 was developed to be applied in the most diverse areas that can significantly benefit from an ERA5 full-resolution model.

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