Changes in specific airway resistance during prolonged breathing of moist air

1970 ◽  
Vol 48 (9) ◽  
pp. 592-597 ◽  
Author(s):  
G. Norris Melville ◽  
W. T. Josenhans ◽  
W. T. Ulmer
Keyword(s):  
Relative Humidity ◽  
Water Content ◽  
Water Loss ◽  
Healthy Subjects ◽  
Airway Resistance ◽  
Tap Water ◽  
Distilled Water ◽  
Moist Air ◽  
Specific Airway Resistance ◽  
Water Elimination

Effects of increased water content of inspired air at 21–38 °C on specific airway resistance (sRaw) in 107 healthy subjects were measured with a body plethysmograph. Mean sRaw increased insignificantly at 23 °C with 92% relative humidity (water content, 20.7 g∙m−3) for up to 71 h but became significant at 6 h with water content 25 g∙m−3. Increases were greater when evaporated tap water was inhaled than when distilled water was used. It is postulated that the increase in sRaw is due to mucosal swelling and to contaminants in tap water. A theory of respiratory "water elimination" is proposed to replace the concept of respiratory water loss.

The Evaporation of Water from Helix Aspersa

1964 ◽  
Vol 41 (4) ◽  
pp. 759-769
Author(s):  
JOHN MACHIN
Keyword(s):  
Water Content ◽  
Water Loss ◽  
Vapour Pressure ◽  
Freezing Point ◽  
Muscular Activity ◽  
Helix Aspersa ◽  
Distilled Water ◽  
Atmospheric Conditions ◽  
Evaporative Water ◽  
Dry Air

1. Observations of intact specimens of Helix aspersa together with experiments with isolated skin preparations are described. 2. Under normal atmospheric conditions increases in haemocoelic pressure, probably due to general muscular activity, are sufficient to maintain the superficial mucous coating of the skin. 3. Under conditions of rapid water loss more intense muscular undulations serve to spread mucus which collects in the grooves to more exposed areas of the skin. 4. The water content, the rate of water loss in dry air, the equilibrium in saturated air and depression of freezing point of isolated mucus samples have been measured. 5. The vapour pressure of mucus has been shown to be within 0.4% of that of distilled water under the same conditions. 6. The significance of the above findings is discussed in relation to evaporative water loss and water uptake of an intact snail.

scholarly journals Osmotic Conditions During the Embryonic and Early Larval Life of the Brook Lamprey (Lampetra Planeri)

1957 ◽  
Vol 34 (2) ◽  
pp. 237-252
Author(s):  
M. W. HARDISTY
Keyword(s):  
Water Content ◽  
Tap Water ◽  
Initial Permeability ◽  
Distilled Water ◽  
Continuous Increase ◽  
Outer Membranes ◽  
Lampetra Planeri ◽  
Short Time ◽  
Osmolar Concentration ◽  
Whole Egg

1. Observations have been made on the swelling of eggs in tap and distilled water. The rate of uptake of water through the outer membranes and the surface of the ovum fell off sharply within a short time of contact with water. In distilled water uptake into the perivitelline space was very much greater than in tap water, but there were no significant differences in the volume of the ovum itself in these two media. 2. The initial permeability of the ovum to water has been estimated as 0.049 µ3/µ2atm./min., falling after about 7 hr. to 0.003 and remaining at this level for the first 5 days of development. 3. The outer egg membranes are apparently freely permeable to water and ions, and the mean Cl concentration of the perivitelline fluid in the later stages of development was found to be only 2.4 mM/l. 4. Evidence is presented which points to a decrease in the volume of the embryo at some point between gastrulation and hatching. In tap water a contraction of the whole egg was observed from the fifth day onwards. 5. The water content of the embryo at hatching was not very much greater than that of the ovarian egg. After hatching, until the absorption of the yolk, there was a continuous increase in the fresh weight and water content of the ammocoetes. 6. The evidence suggests that the ovarian egg is in osmotic equilibrium with the peritoneal fluid (mean 110 mM/NaCl/l.). During development the osmolar concentration of the total egg fluid was reduced to values similar to those calculated from the known dilution, i.e. 30-40 mM/l. At hatching, the osmolar concentration of the embryo (80 mM/l.) was raised within a few days to 11-120 mM/l. 7. The observed reduction in Cl concentration of the whole egg was much greater than that calculated from the increases in volume. The Cl concentration of the embryo itself was reduced from an initial value of 56 to 15 mM/l. embryo fluid a week before hatching. 8. Determinations of the total Cl content of whole eggs and embryos showed a very marked loss of Cl ions in the two days following fertilization. Within 35 days after hatching the Cl level had been raised by active uptake to about four times the values at the time of hatching.

scholarly journals The interdependence between transpiration intensity and the anatomical structure of moss leaves

2015 ◽  
Vol 46 (1) ◽  
pp. 57-68 ◽  
Author(s):  
J. Krupa
Keyword(s):  
Relative Humidity ◽  
Water Content ◽  
Water Loss ◽  
Cell Walls ◽  
Anatomical Structure ◽  
Atmospheric Humidity ◽  
Respiration Activity ◽  
Funaria Hygrometrica ◽  
Relative Atmospheric Humidity

The degree of anatomical differentiation of moss leaves, as well as differing biotropic conditions of these plants, served as a basis for the choice of the following species: <i>Mnium punctatum, Catharinea undulata, Funaria hygrometrica, Polytrichum juniperinum, Polytrichum piliferum</i>, and <i>Aloina rigida</i>. Different anatomical structure of severed moss leaves does not generally influence the quantity of water evaporated during a 24-hour period, while they are kept in an atmosphere of relative humidity of 85% and 95%. The differences observed in the dynamics of water loss from leaves under conditions of relative atmospheric humidity of 85% are more likely due to the properties and structure of cell walls, though they may also, result from different resistance of cytoplasm to evaporation. The process of photosynthesis exhibits a significantly greater sensitivity to variations in water content of leaf than does the process of respiration. In most of the studied species, the respiration activity decreases markedly, though it does not become completely arrested following the period of dehydration applied.

scholarly journals THE EFFECT OF WATER CONTENT UPON THE RATE OF HEAT DENATURATION OF CRYSTALLIZABLE EGG ALBUMIN

1933 ◽  
Vol 17 (1) ◽  
pp. 21-34 ◽  
Author(s):  
H. Albert Barker
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Water Content ◽  
Arrhenius Equation ◽  
Heat Denaturation ◽  
Distilled Water ◽  
Egg Albumin ◽  
Thermal Death ◽  
Definite Time ◽  
Denaturation Rate

1. The denaturation rate of partially dried crystallizable egg albumin is greatly decreased by decreasing its water content. 2. The temperature of denaturation, defined as the temperature at which half of the protein becomes insoluble in distilled water after a definite time of heating, is a linear function of the relative humidity with which the protein is in equilibrium. 3. By applying the Arrhenius equation it is shown that the rate of heat denaturation at a given temperature is an exponential function of the relative humidity. 4. The application of the observed relations to the analysis of the mechanism of thermal death of microorganisms is suggested. 5. The water content of native and heat-denatured egg albumin is determined as a function of the relative humidity of water vapor. It is shown that the heat-denatured modification takes up approximately 80 per cent as much water at all relative humidities as does native egg albumin.

scholarly journals A Study of Moist Air Condensation Characteristics in a Transonic Flow System

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4052
Author(s):  
Jie Wang ◽  
Hongfang Gu
Keyword(s):  
Mach Number ◽  
Relative Humidity ◽  
Transonic Flow ◽  
Flow System ◽  
Plane Surface ◽  
Droplet Growth ◽  
Moist Air ◽  
Dry Air ◽  
Hydraulic Equipment ◽  
Non Equilibrium

When water vapor in moist air reaches supersaturation in a transonic flow system, non-equilibrium condensation forms a large number of droplets which may adversely affect the operation of some thermal-hydraulic equipment. For a better understanding of this non-equilibrium condensing phenomenon, a numerical model is applied to analyze moist air condensation in a transonic flow system by using the theory of nucleation and droplet growth. The Benson model is adopted to correct the liquid-plane surface tension equation for realistic results. The results show that the distributions of pressure, temperature and Mach number in moist air are significantly different from those in dry air. The dry air model exaggerates the Mach number by 19% and reduces both the pressure and the temperature by 34% at the nozzle exit as compared with the moist air model. At a Laval nozzle, for example, the nucleation rate, droplet number and condensation rate increase significantly with increasing relative humidity. The results also reveal the fact that the number of condensate droplets increases rapidly when moist air reaches 60% relative humidity. These findings provide a fundamental approach to account for the effect of condensate droplet formation on moist gas in a transonic flow system.

Modeling Vapor Transport in a Hollow Fiber Membrane Humidifier Using ε-NTU Approach

2020 ◽  
Author(s):  
Hoang Nghia Vu ◽  
Xuan Linh Nguyen ◽  
Sangseok Yu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Fuel Cell ◽  
Relative Humidity ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Water Content ◽  
Vapor Transport ◽  
Overall Mass Transfer Coefficient ◽  
Mass Exchanger

Abstract In a fuel cell vehicle, the water content of the gas supply within certain ranges plays a key role in improving the performance of a proton exchange membrane. The lower limit of water content in the air supply is to avoid the problem of drying-out, while the upper prevents flooding. Water management can be accomplished by a membrane humidifier which allows water vapor to permeate the mixture from the side having the higher water concentration, moving to the other side of the membrane. In this study, the variation in water content collected at the outlet of a membrane humidifier is investigated with a one-dimensional mass exchanger model and various operating variables. The vapor concentration of outlet flows is affected by operating temperature and relative humidity of the membrane humidifier. Relative humidity of the dry side at the point of outlet flow, to be supplied to the fuel cell module, is the key characteristic. The analogy of the effectiveness-NTU approach for heat transfer is used to analyze the characteristics of the mass exchanger. Mass flux through the membranes is estimated with an overall mass transfer coefficient which represents vapor transport characteristics moving through the membrane module. This coefficient has a similar role to the overall heat transfer coefficient in heat exchanger analysis. This parametric study is conducted to understand the effects of different variables. The Effectiveness-NTU methodology of mass transfer uses the overall mass transfer coefficient and the mass transfer rate, as evaluated experimentally. Simulink software is then employed to deliver outcomes of the model for different operating conditions.

scholarly journals Assessment of lettuce quality during storage at low relative humidity using Global Stability Index methodology

2012 ◽  
Vol 32 (2) ◽  
pp. 366-373 ◽  
Author(s):  
María Roberta Ansorena ◽  
María Victoria Agüero ◽  
María Grabriela Goñi ◽  
Sara Roura ◽  
Alejandra Ponce ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Relative Humidity ◽  
Global Stability ◽  
Water Content ◽  
Relative Water Content ◽  
Storage Time ◽  
Stability Index ◽  
Total Chlorophyll ◽  
External Zone ◽  
Relative Water

During postharvest, lettuce is usually exposed to adverse conditions (e.g. low relative humidity) that reduce the vegetable quality. In order to evaluate its shelf life, a great number of quality attributes must be analyzed, which requires careful experimental design, and it is time consuming. In this study, the modified Global Stability Index method was applied to estimate the quality of butter lettuce at low relative humidity during storage discriminating three lettuce zones (internal, middle, and external). The results indicated that the most relevant attributes were: the external zone - relative water content, water content , ascorbic acid, and total mesophilic counts; middle zone - relative water content, water content, total chlorophyll, and ascorbic acid; internal zone - relative water content, bound water, water content, and total mesophilic counts. A mathematical model that takes into account the Global Stability Index and overall visual quality for each lettuce zone was proposed. Moreover, the Weibull distribution was applied to estimate the maximum vegetable storage time which was 5, 4, and 3 days for the internal, middle, and external zone, respectively. When analyzing the effect of storage time for each lettuce zone, all the indices evaluated in the external zone of lettuce presented significant differences (p < 0.05). For both, internal and middle zones, the attributes presented significant differences (p < 0.05), except for water content and total chlorophyll.

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