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PubMed2006

3D quantification of microclimate volume in layered clothing for the prediction of clothing insulation.

Garment fit and resultant air volume is a crucial factor in thermal insulation, and yet, it has been difficult to quantify the air volume of clothing microclimate and relate it to the thermal insulation value just using the information on the size of clothing pattern without actual 3D volume measurement in wear condition. As earlier methods for the computation of air volume in clothing microclimate, vacuum over suit and circumference model have been used. However, these methods have inevitable disadvantages in terms of cost or accuracy due to the limitations of measurement equipment. In this paper, the phase-shifting moiré topography was introduced as one of the 3D scanning tools to measure the air volume of clothing microclimate quantitatively. The purpose of this research is to adopt a non-contact image scanning technology, phase-shifting moiré topography, to ascertain relationship between air volume and insulation value of layered clothing systems in wear situations where the 2D fabric creates new conditions in 3D spaces. The insulation of vests over shirts as a layered clothing system was measured with a thermal manikin in the environmental condition of 20 degrees C, 65% RH and air velocity of 0.79 m/s. As the pattern size increased, the insulation of the clothing system was increased. But beyond a certain limit, the insulation started to decrease due to convection and ventilation, which is more apparent when only the vest was worn over the torso of manikin. The relationship between clothing air volume and insulation was difficult to predict with a single vest due to the extreme openings which induced active ventilation. But when the vest was worn over the shirt, the effects of thickness of the fabrics on insulation were less pronounced compared with that of air volume. In conclusion, phase-shifting moiré topography was one of the efficient and accurate ways of quantifying air volume and its distribution across the clothing microclimate. It is also noted that air volume becomes more crucial factor in predicting thermal insulation when clothing is layered.

Body Temperature Regulation↗

PubMed1998

Flight coverall microclimate evaluation using a Japanese type sweating mannequin.

BACKGROUND: It is important to examine the microclimate of a pilot's clothing to evaluate the heat stress the clothing imparts on a pilot, but problems arise with regard to individual variation (phenotype of the pilot, sweating dose, wear condition of the flight coveralls, etc.). HYPOTHESIS: The present study used a Japanese type sweating mannequin (TOM-III) to evaluate the microclimate of flight coveralls. METHODS: TOM-III (TOYOBO, Co., Ltd., Tokyo, Japan) has a characteristic Japanese human body type, and the sweat rate and body temperature can be regulated (240 g of sweat per hour, 36.0 degrees C). The microclimate of the clothing was evaluated by means of 20 temperature/humidity sensors located on the surface of the mannequin skin. TOM-III wore four different assemblies of clothing (CWU-66/P USAF chemical defense flight coverall; JASDF summer-type flight coverall which is similar to the nonchemical defense USAF flight coverall; ordinary 100% cotton underwear; and CWU-66/ P with cotton underwear). We put TOM-III in climatic chamber (21.2 +/- 0.5 degrees C, 50.0 +/- 3.0% relative humidity (RH), 0.1 m air flow x s(-1), dressed in test clothing, and measured the inside temperature (IT) and inside relative humidity (IRH) of the clothing for 60 min (10 min non-sweating, 30 min sweating and 20 min non-sweating). RESULTS: Approximately 5 min after the onset of sweating, the IRH of the CWU-66/P (38.0%) was lower than JASDF flight coverall (42.1%; p < 0.01). At the end of the sweating period, the IRH of the CWU-66/P and the JASDF flight coverall were 46.2% and 52.6%, respectively (p < 0.01). The results indicated that the CWU-66/P flight coverall was better suited for heat stress than the JASDF summer-type flight coverall. CONCLUSIONS: TOM-III may be useful for microclimate evaluation and/or the development of clothing without considering individual variation against various climatic conditions.

Aerospace Medicine↗

PubMed2004

Predicting psychrometric conditions in biocontaminant microenvironments with a microclimate heat and moisture transfer model -- description and field comparison.

UNLABELLED: A numerical model is described that is designed to model psychrometric conditions in biocontaminant microenvironments, such as in bedding and the base of carpets for dust-mites, and on the surface of linings for molds. The model is very general and can include room air, other room components, other zones including the outdoors, other rooms and any subfloor space. Mechanical plant can be modeled. Good agreement between modeled and field results are reported for the complex case of an occupied bed and for the microclimate in the base of a carpet, before and after its timber floor above a crawl space was retrofitted with insulation. PRACTICAL IMPLICATIONS: Biocontaminants such as dust-mites and molds can pose serious health problems. Understanding microclimates in biocontaminant microhabitats, when coupled with biologic models, will make it possible to predict how the life cycles of these biocontaminants are affected as these conditions change. In turn, this will suggest which interventions that modify indoor climate and microclimate are likely to control these biocontaminants. Furthermore such interventions might include indoor humidity control, changing building insulation and ventilation levels, covering mattresses, use of electric blankets, use of carpet heating, etc. Such models will provide a fast way for screening for interventions that are likely to be effective in the control of biocontaminants.

Air Pollutants↗

PubMed1999

The effects of fabric air permeability and moisture absorption on clothing microclimate and subjective sensation in sedentary women at cyclic changes of ambient temperatures from 27 degrees C to 33 degrees C.

The present paper aimed at learning the effects of two different levels of air permeability and moisture absorption on clothing microclimate and subjective sensation in sedentary women. Three kinds of clothing ensemble were investigated: 1) polyester clothing with low moisture absorption and low air permeability (A clothing); 2) polyester clothing with low moisture absorption and high air permeability (B clothing); and 3) cotton clothing with high moisture absorption and high air permeability (C clothing). After 20 min of dressing time, the room temperature and humidity began to rise from 27 degrees C and 50% rh to 33 degrees C and 70% rh over 20 min, and it was maintained for 30 min (Section I); it then began to fall to 27 degrees C and 50% rh over 20 min, and it was maintained there for 20 min (Section II). The subject sat quietly on a chair for 110 min. The main findings are summarized as follows: 1) The clothing surface temperature was significantly higher in C clothing than in B clothing during section I, but it was significantly higher in B clothing than in C clothing during section II. 2) Although the positive relationship between the microclimate humidity and forearm sweat rate was significantly confirmed in all three kinds of clothing, the microclimate humidity at the chest for the same sweat rate was lower in C clothing than in A and B clothing. These results were discussed in terms of thermal physiology.

Adult↗

PubMed2006

[Microclimate edge effects of evergreen broad-leaved forest fragments in Jinyun Mountain: a preliminary study].

This paper studied the microclimate of continuous and fragmental evergreen broad-leaved forests in Jinyun Mountain by determining the horizontal gradient distribution of microclimate elements near forest edges. The results showed that there existed clear edge effects of microclimate in every edge of fragmental forests. The distinctions of maximum and minimum air temperature, photosynthetic active radiation, and minimum relative humidity between edge forest and interior forest were higher or greater, while that of maximum ground surface temperature was lower or smaller in dry season than in rain season. The edge effect was the smallest in the biggest fragmental patch, but the greatest in the smallest fragmental patch in interior forest.

China↗

PubMed1990

[Quantitative evaluation of combined effects of carbon monoxide, toluene and hot microclimate on humans].

As a result of the proposed study it was established that a complex action of carbon oxide and toluene++ in 300 mg/m3 concentration in a combination with heating microclimate (leading to a maximum heat labour condition) results in an increased total biological effect. The coefficient to the complex action of carbon oxide and heating microclimate is equal to 2.5 and toluene++ and heating microclimate to 1.9. These coefficients should be taken into account in establishing hygienic norms for the chemical compounds.

Adult↗

PubMed1990

[Combined effects of toluene and hot microclimate on human body].

It is shown in the paper that sensitivity of human organism to the toxic action of toluene is not changed under exposure to the microclimate, producing allowable thermal state, and is increased under exposure to the heating microclimate leading to the development of maximum thermal state. Under toluene exposure in the concentration 300 mg/m3 resistance to the heating microclimate under the conditions of joint exposure to these factors is reduced, which is manifest in an earlier onset of the maximum thermal state in people under observation.

Adult↗

PubMed1989

[The combined action of carbon monoxide and a heating microclimate on the human body under extreme conditions].

Through the research performed it was established that man's sensitivity to the toxic properties of carbon oxide (CO) is not influenced by microclimates with permissible temperature characteristics, and the sensitivity increases under the influence of heating microclimates leading to the limit temperature conditions. With carbon oxide (CO) in concentration 300 mg/m3, the endurance of heating microclimate under a complex influence of these factors decreases what manifests itself in earlier limit temperature conditions of the examined persons.

Adult↗

PubMed1978

Heat acclimatization by a method utilizing microclimate cooling.

A new approach to heat acclimatization has been shown to be feasible during laboratory experimentation. Wearing microclimate suits containing dry ice as the coolant, three groups of men were subjected to a moderate work rate in three different environments for 4 h/d for 8 d. Physiological responses on a subsequent heat tolerance test indicate that the group subjected to an environment of 32.0 degrees C W. B. and 33.5 degrees C D.B. were fully heat acclimatized. The 33/35 degrees C group were also well-acclimatized but developed dangerously high body temperatures during the first 2 d. Only partial acclimatization was achieved by the 31/33 degrees C group. The reason why the men acquire heat acclimatization while wearing the microclimate suits in a hot environment is probably that microclimate cooling does not prevent body temperature from rising--it only prevents it from rising excessively. It should be remembered that only one-third of the body is cooled while the rest shows the normal sweating response.

Acclimatization↗

PubMed1994

Mucosal acidification and an acid microclimate in the hen colon in vitro.

Experiments were performed on isolated, stripped colonic epithelia of low-salt-adapted hens (Gallus domesticus) in order to characterize acid secretion by this tissue. With symmetric, weak buffer solutions, colonic epithelia acidified both mucosal and serosal sides. Titration measurements of the mucosal acidification rate (pH-stat technique) averaged 1.63 +/- 0.25 microEq.cm-2.h-1. Mucosal acidification was also evident in colons from high-salt-adapted birds and in low-salt-adapted coprodeum, but was completely abolished in the high-salt coprodeum. Mucosal acidification by low-salt-adapted colonic epithelium was unaffected by sodium replacement, mucosal amiloride (10(-3) mol.l-1), and serosal ouabain (5 x 10(-4) mol.l-1), although all three treatments significantly reduced or reversed the short-circuit current. Acetazolamide (10(-3) mol.l-1, serosal) reduced mucosal acidification by 15% and simultaneously increased short-circuit current by a similar amount. Colonic epithelia incubated in glucose-free solutions had significantly lower acidification rates (0.59 +/- 0.13 microEq.cm-2.h-1, P < 0.002 versus controls) and addition of glucose (15 mmol.l-1), but not galactose, partially restored acidification to control levels. Anoxia (N2 gassing) completely inhibited short-circuit current, but reduced acidification by only 30%. A surface microclimate pH, nearly 2 pH units more acidic than the bath pH of 7.1-7.4, was measured in low-salt-adapted colon and coprodeum. The acid microclimate of both tissues was partially attenuated by adaptation to a high-salt diet. Colonic microclimate pH was dependent on the presence of glucose and sensitive to the bath pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗

PubMed1992

Effects of propionate on the acid microclimate of hen (Gallus domesticus) colonic mucosa.

1. Short-chain fatty acid absorption in hen colon is protonated across the apical border coupled to an apical electrogenic proton pump. 2. The surface pH of the isolated colonic epithelium was 6.27 +/- 0.05, when incubated in Krebs-phosphate buffer pH 7.0. 3. Propionate 7 and 40 mmol/l in the incubation medium (pH 7.0) increased microclimate pH to 6.47 +/- 0.04 and 6.56 +/- 0.04. Inhibition of metabolic activity by potassium cyanide 1 mmol/l increased surface pH to 6.66 +/- 0.06. 4. The calculated concentration of propionic acid in the microclimate is near-linearly related to the propionate concentration. Thus, the acid microclimate is not responsible for the Michaelis-Menten like kinetics of propionate transport.

Animals↗

PubMed2005

Mapping neutral microclimate pH in PLGA microspheres.

A quantitative ratiometric method based on laser scanning confocal microscopic imaging was developed to create a pixel-by-pixel neutral microclimate pH (5.8-8.0) map inside poly(lactic-co-glycolic acid) (PLGA) microspheres. The method was accurate to within +/-0.2 pH units. PLGA microspheres with encapsulated bovine serum albumin and the pH-sensitive dye, SNARF-1(R) dextran (MW=10 kDa), were prepared by a water-in-oil-in-water solvent evaporation method. The imaging method was used to monitor the pH changes in PLGA microspheres with or without co-encapsulation of acid-neutralizing MgCO3, and for three different microsphere sizes (2.0+/-0.3, 40+/-10 and 137+/-32 microm) during incubation under physiological conditions. The pH of microspheres was significantly higher with co-encapsulated base compared to base-free microspheres, whose microclimate pH was predominantly below the dye detection limit of pH=5.8. The small microspheres displayed a more neutral pH during incubation probably due to their much shorter diffusion path for polymer-dissolved acids compared with medium- and large-size microspheres. The pH mapping technique discussed here may be useful in routine formulation development and for elucidation of mechanisms of microclimate pH development and polymer erosion.

Drug Delivery Systems↗

PubMedDate not supplied

[A plea for comprehensive interpretation in microclimate areas].

Microclimate is an important factor in modern intensive stockbreeding. At any rate, it ought to be judged in the context of other stress factors. Since microclimate is variable in the stable, it ought to be measured with the purpose of possibly effectuating a correction. The microclimate of a stable, which is also dependent on the outer climate situation, cannot always be improved solely by means of ventilation. However, the ventilation system should always be coordinated with the dung removal system of the stable.

Animal Husbandry↗

PubMed1980

[The effect of suction and pressure type of ventilation on the microclimate of fattening stations and on the production performance of pigs].

The microclimate in fattening houses of the TEROZ TACHOV type was studied in two fattening seasons. One of the houses had the original ventilation based on negative pressure and the other was tested as to the function and effect of overpressure ventilation. Under the given conditions, the comparison of the two systems showed that the pressure ventilation drove more air through the zone where the animals were kept, and was connected with higher cooling. Dust nuisance was reduced by the pressure ventilation system, but the temperatures and humidites in the fattening houses were influenced, since it slightly increased the temperatures in the house as a result of the flow of hot air from outside in summer, and considerably cooled the microclimate in the house in winter. Nevertheless, the pressure ventilation system provided a better microclimate for the pigs: their gains were higher and the mortality was lower.

Animal Husbandry↗

PubMed1975

[Various indices of microclimate in the newly built and re-adapted stables for race horses].

A study was performed to examine microclimate in 14 stables belonging to 10 horsemen's teams and clubs; five of these houses were new-built. In five race-horse stables housing 16 horses each, on an average, where the optimum air temperature ranged from 10 degrees C to 12 degrees C, measurements and examinations were performed in the winter period and the following results were obtained: space per 1 horse housed 42.9 plus or minus 8.7 m-3, relative air humidity 74.3 plus or minus 3.8%, CO2 concentration 0.175 plus or minus 0.027%, NH3 concentration 0.00135 plus or minus 0.00044%. A large majority of horse stables under our conditions lack suitable ventilating equipment for winter and for cold periods. Together with the present-day building technology and with excessive space of box-type houses, this implies that microclimate conditions are unsuitable and harmful to health; in particular, this is true of cold and wet conditions. In the existing stables this problem can be solved by additional heating, preferably with the hot-air system. It is necessary that horse stables should have good thermal-insulation characteristics, with plastered brick walls 45 cm in thickness and with thermally insulated loft. Floors must be solid, hard, and plane. Modern building technology and new materials must secure all the required parameters, with due respect to all factors constituting microclimate and to purposeful layout of race horse stables. It appears desirable to issue a state standard for the construction of horse stables.

Air Conditioning↗

PubMed1998

[Sanitary evaluation of microclimate conditions at the ore mining and alluvial pits sites].

The authors summarized results of hygienic research carried in pits of Transbaikal region, Yakutia. Tchukotka, Kazakhstan, Kirgizia, Krivoy Rog, European North and other areas. Microclimate parameters in winze of mining and alluvial pits appeared to vary significantly and to depend on certain specific factors (depth of mining, climate geographic zone of the enterprise, temperature of the ores treated, etc.). Considering degree of influence on workers' heat state, taking into account significance of clothes heat insulation required, the authors defined 4 types of microclimate at workplace. For operative selection of optimal special clothing set, the authors represent dependence of proper heat resistance of clothes for main and auxiliary occupations on microclimate conditions.

Climate↗

PubMed2007

Microclimate of tree cavities during winter nights-implications for roost site selection in birds.

We examined the relationships between cavity temperature, ambient temperature outside the cavity and structural characteristics of 70 cavities measured for 1 night to determine if cavity roosting birds may potentially select warmer tree cavities for wintertime roosting. The mean temperature increment of the cavity (=cavity-ambient temperature) varied from -2.4 to 4.9 degrees C and increased with higher day-to-night fluctuations in the ambient temperature, smaller cavity entrance and better health status of the cavity tree. Cavities in healthy trees were warmer than those in dead trees, but this difference disappeared with rising mean ambient temperatures. This interaction between the effects of tree health status and mean ambient temperature, as well as the effect of day-to-night fluctuations in the ambient temperature, were supported by the analysis of repeated measurements of temperature taken on 12 consecutive nights in five cavities. The variability in cavity microclimates makes the selection of warmer roost sites possible, and the predictors of microclimate may provide indirect cues to prospecting birds.

Animals↗

PubMed2006

Design and control optimization of microclimate liquid cooling systems underneath protective clothing.

The use of protective clothing, whether in space suits, hazardous waste disposal, or sporting equipment, generally increases the risk of heat stress and hyperthermia by impairing the capacity for evaporative heat exchange from the body to the environment. To date the most efficient method of microclimate cooling underneath protective clothing has been via conductive heat exchange from circulating cooling fluid next to the skin. In order to make the use of liquid microclimate cooling systems ((LQ)MCSs) as portable and practical as possible, the physiological and biomedical engineering design goals should be towards maximizing the efficiency of cooling to maintain thermal comfort/neutrality with the least cooling possible to minimize coolant and power requirements. Meeting these conditions is an extremely complex task that requires designing for a plethora of different factors. The optimal fitting of the (LQ)MCSs, along with placement and design of tubing and control of cooling, appear to be key avenues towards maximizing efficiency of heat exchange. We review the history and major design constraints of (LQ)MCSs, the basic principles of human thermoregulation underneath protective clothing, and explore potential areas of research into tubing/fabric technology, coolant distribution, and control optimization that may enhance the efficiency of (LQ)MCSs.

Cold Temperature↗