SEARCH · PubMed Health

Results for “Humidity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources

PubMed1996

Influence of storage humidity on hardness of light-cured glass polyalkenoate cements.

The influence of storage in various environments on the hardness of four commercial light-cured glass polyalkenoate cements and one conventional glass polyalkenoate cement was investigated. Specimens with or without light exposure were stored for 7 days in different humidity conditions. A hardness tester with a diamond indenter point was used and Vickers hardness numbers under minor load conditions were determined. Non-light-exposed specimens did not increase in hardness in either dry or wet conditions. Light-exposed specimens became harder with time in dry conditions. Light-exposed specimens stored in wet conditions hardened only slightly. To investigate the effects of humidity, some light-exposed specimens stored first in wet conditions were stored another 7 days in dry conditions. They became as hard as those first stored in dry conditions for 7 days. It is concluded that the hardness of these cements corresponds with the humidity of the storage environment.

Acrylic Resins↗

PubMed1987

Circulatory and thermal responses of men with different training status to prolonged physical work in dry and humid heat.

Eight physically trained and eight untrained, unacclimated men walked on a treadmill at 30% of their maximum oxygen consumption up to 3.5 h in a thermoneutral [20 degrees C/40% relative humidity (RH)], a warm humid (30 degrees C/80% RH), and a hot dry (40 degrees C/20% RH) environment while wearing industrial work clothing. Their oxygen consumption, rectal and skin temperatures, sweating, cardiac output, heart rate, stroke volume, and peripheral blood pressure were measured during the tests. Thirteen of the 32 heat stress tests were prematurely stopped due to high rectal temperature, high heart rate, subjective fatigue, or heat syncope. The physiological strain, as indicated by the rectal temperature and heart rate, was not significantly different between the warm humid and hot dry environments (wet bulb globe temperature approximately 28 degrees C). The rectal temperature and heart rate responses of the physically trained and untrained subjects did not differ in any of the environments. In the heat, the heart rate was significantly higher than in the thermoneutral environment, but because of the markedly reduced stroke volume the average cardiac output was not different between the three environments. The impaired work performance in the heat seemed mainly to be related to the circulatory instability accompanying the increased cutaneous circulation.

Adult↗

PubMed1999

Effects of humid heat exposure on human sleep stages and body temperature.

The objective of this study was to confirm the effect of humid heat exposure on sleep stages and body temperature. Seven healthy male volunteers with a mean age of 22.7+/-1.63, served as the subjects. The experiments were carried out under four different conditions of room temperature and relative humidity: 29 degrees C RH 50% (29/50), 29 degrees C RH 75% (29/75), 35 degrees C RH 50% (35/50), and 35 degrees C RH 75% (35/75). The subjects wearing only shorts slept from 23:00 to 7:00 on a bed, which was covered with a 100% cotton sheet. EEG, EOG, and mental EMG were recorded through the night. Rectal temperature (Tr) and skin temperature were measured continuously. The 35/75 condition caused more wake and a lower sleep efficiency index (SEI) and stage S3+S4 than 29/50 and 29/75. Stage REM and stage 3 were significantly decreased at 35/75 than at 29/50 and 35/50. Tr was maintained at a higher level at 35/75 than under the other conditions. Mean skin temperature was higher at 35/50 and 35/75 than at 29/50 and 29/75. These results suggest that humid heat exposure during night sleep increases the thermal load to supress the sleep-evoked Tr decrease, stage 3, SWS, and REM, and increase wakefulness.

Adult↗

PubMed2001

[Effect of temperature, relative humidity and photoperiod on embryonic development and egg hatch of Pirata piraticus].

In this paper, the effects of temperature, relative humidity and photoperiod on embryonic development and egg hatch of Pirata piraticus were investigated. Temperature affected not only the whole course of embryonic development, but also its different phases. At 20 degrees C-35 degrees C, as temperature increased, the embryonic development became faster. The developmental threshold of egg was estimated to be at 11.9 degrees C. The uniform degree of egg hatch was higher at low temperature, while the highest hatching rate was happened at 28 degrees C. In order to study the factors affecting embryonic development and to determine the optimum condition for egg hatch, experiments were arranged by quadratic regression rotation composite design with three factors: temperature (X1), relative humidity (X2) and photoperiod (X3). Three models were built up, and the factors affecting the embryonic development were analyzed. After calculating the hatching rate using the model of hatching rate by computer, the optimum condition for egg hatch of the spider was given: temperature 27 degrees C-28.5 degrees C, relative humidity 94%-97%, and photoperiod 14-17 h.

Animals↗

PubMed2002

Time of survival under starvation in two flea species (Siphonaptera: Pulicidae) at different air temperatures and relative humidities.

We studied the effect of air temperature and RH on the survival time of adult Xenopsylla conformis Wagner, 1903 and Xenopsylla ramesis Rothschild, 1904 fleas during starvation to explain the paratopic habitat distribution of these species on opposite ends of a precipitation and temperature gradient in the Negev Highlands, Israel. We hypothesized that the pattern of distribution of the two flea species is caused by differential microclimatic preferences of imagoes and predicted that (1) the resistance to starvation would differ between the two flea species at different air temperatures (10 degrees C - 38 degrees C) and relative humidities (RH) (40%-92%) and (2) survival time of starving X conformis would be longer than that of starving X ramesis at high air temperatures and low RHs. Survival time of newly emerged X conformis was dependent on air temperature but not on RH, whereas in newly emerged X ramesis it was affected by both air temperature and RH. Generally, survival time of newly emerged fleas was longer at lower air temperatures and higher humidities than at higher air temperatures and lower humidities. No significant difference in survival time between species in dependence on either air temperature or RH were found for newly emerged fleas. Fed fleas of both species responded similarly to changes in air temperature and RH in terms of survival time. Survival time at lower temperatures was longer than that at higher temperatures. Females survived longer than males at all air temperatures except for the highest temperature when the survival time of both sexes was similarly low. In both species, the effect of RH on survival time was significant at the highest RH only, with a decrease in survival time at 92% RH. In contrast, survival times at lower RHs did not differ. Males of both species survived for less time than females at all RHs. X conformis generally survived for less time than X ramesis, all else being equal. The only regime at which X conformis survived longer than X. ramesis was 38 degrees C and 40% RH. Newly emerged fleas survived for significantly longer time than fed fleas.

Adaptation, Physiological↗

PubMed2002

[Bacterium culture and flora analysis of gunshot wound on limbs of dogs in hot and humid environment].

OBJECTIVE: To investigate the time of bacterial invasion into the blood and conduct flora analysis of the blood and secretions in the gunshot wound in the limbs of dogs in hot and humid environment. METHODS: Gun-shot wound was induced in 8 dogs who were subsequently assigned at random into hot and humid environment (HHE) group and normal environment (NE) group for observation. At the time points of 0, 4, 6, 8, 12, 24 h after injury, body temperature was measured and bacterial culture and flora analysis performed. RESULTS: Body temperature elevation occurred earlier and lasted for longer time in HEE group than in NE group. Bacterial invasion into the blood occurred at 12 h after the injury in NE group, but at 8 h in HHE group. In the wound tracts of the dogs, surface bacteria were found in both groups. Surface bacteria were also found in the blood of dogs in both groups, but in HHE group, even intestinal flora were identified. CONCLUSION: Body temperature elevation and bacterial invasion into the blood occurred at an earlier time in hot and humid environment where migration of intestinal bacteria into the blood easily takes place, indicating the early application of broad-spectrum antibiotics under such environmental conditions.

Animals↗

PubMed2002

[Influence of soil humidity and vegetation coverage on wind erosion].

Wind erosion is becoming a constraining factor to agriculture and animal husbandry in the arid and semiarid area of Luanhe River. In this paper, wind erosion process was studied through simulation experiments. The results showed that soil humidity and vegetation coverage were the main factors affecting wind erosion. The wind erosion rate was decreased with increasing soil humidity and vegetation coverage, and hence, wind erosion process was reduced by modulating soil humidity and vegetation coverage in human activities.

Ecology↗

PubMed1997

[Relationship between variations of temperature and humidity with reproduction of medical meloids].

This paper reports the relationship between variations of temperature and humidity with reproduction of two medical meloids (Mylabris phalerata, M. cichorii). The results show: for the copulation of two meloids, the suitable temperature is 22-28 degrees C, humidity 26-90%; for the suitable temperature and humidity of their oviposition, M. phalerata 26-28 degrees C and 60-68%, and M. cichorii 23-26 degrees C and 72-78%, respectively; for incubation, M. phalerata is 26-28 degrees C and 70-75% respectively, and M. cichorii must undergo the high and lower variation of temperature, the efficacious accumulative temperature must get of 1680.85 day. degrees C.

Animals↗

PubMed2002

Effect of relative humidity on bond strength of self-etching adhesives to dentin.

PURPOSE: The aim of the study was to investigate the effect of the relative humidity of the ambient air on the dentin bonding efficiency of four self-etching primer adhesives. MATERIALS AND METHODS: Three commercially available self-etching primer adhesives, AQ Bond, Fluorobond, One-Up Bond F, and one experimental all-in-one adhesive, AC-Bond, were selected. Peripheral plane dentin surfaces of human molars were prepared with wet SiC paper. Eight specimens were prepared for each of the adhesives and each of the following six conditions prior to application of the bonding agents and a hybrid-type resin composite material: air dried, wet, or stored for 1 h at 33%, 50%, 75%, and 100% relative humidity (RH). Shear bond strength (SBS) was determined after 24 h of storage in water at 37 degrees C. RESULTS: None of the adhesives showed statistically significant differences in SBS between the experimental conditions. AC Bond, AQ Bond, and Fluorobond were equally effective with an average SBS of 19.0 MPa, whereas One-Up Bond F showed a significantly lower mean SBS of 11.5 MPa. CONCLUSION: The self-etching primer adhesives tested are unaffected by the degree of dentin wetness or ambient air humidity exposure prior to application. Unless considered necessary for other clinical reasons, use of rubber-dam is not compulsory.

Adhesives↗

PubMed1992

Study of lipid changes in freeze-dried fish during storage. I. The interaction of relative humidity and tissue lipids.

Several studies on lipid stability of freeze-dried fish pointed out the relationship between relative humidity (RH) and autoxidation of highly unsaturated fatty acids. The present study shows the changes of tissue lipids in two different fish, freeze-dried and stored under various RH conditions. Fillets of Scomber scomber L and Sardina pilchardus sardina were freeze-dried and stored for 1, 3, 6 and 9 months. periodically, the sample of both fish were analyzed to evaluate the autoxidation of lipids. The results show that the autoxidation of lipids is quicker during 1st-3rd month of storage, while in a high humidity environment the tissue lipids change slower. According to these results both time of storage and relative humidity must be controlled to maintain the nutritive value of freeze-dried fish.

Animals↗

PubMed1992

Heat stress in protective clothing: validation of a computer model and the heat-humidity index (HHI).

Ability to work while wearing protective clothing is often limited by rising body temperature. Peterson analyzed the combined effects of heat, humidity and workload using the Texas Model of Thermoregulation and suggested that environmental heat load imposed on a person wearing heavy, semipermeable clothing could be predicted using the Heat-Humidity Index (HHI = 0.5 Tdb + 0.5 Twb), where Tdb = dry bulb temperature and Twb = wet bulb temperature. Our study was designed to: 1) test the validity of this computer model; and 2) evaluate the applicability of the HHI to heavily clothed subjects working in a variety of thermal environments. Nine men wearing chemical defense clothing were each studied under eight conditions over the range Tdb = 20 - 40 degrees C, Tbg = Tdb + 5 degrees C, relative humidity = 9-75%, and oxygen uptake = 14-27 ml.kg-1 x min-1. Variables analyzed included tolerance time (TT), rectal temperature (Tre), skin temperature, heart rate (HR), weight loss, sweat rate, evaporation rate, and evaporative efficiency. Experiments were designed to last 30-180 min, and continued until Tre = 39 degrees C except when subjective tolerance limits occurred first (12 of 72 experiments). The observed time to reach Tre = 39 degrees C bracketed the predicted time in the more severe conditions, but the model seriously underestimated heat storage in the milder conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗

PubMed2004

Bacterial growth characteristics in craniocerebral gunshot wound of cat in a hot and humid environment.

OBJECTIVE: To investigate the growth behavior of characteristics in craniocerebral gunshot wound of cats in a hot and humid environment. METHODS: Twenty-three cross-bred cats were randomly divided into 4 groups: group A, the gunshot wound control group at normal temperature, in which tissue sampling was performed immediately after the wounding; group B, another gunshot wound control group at normal temperature, in which the samples were taken 6 h after the wounding; group C, the gunshot wound group subjected to a hot and humid environment, in which the tissue samples were obtained 6 h after the wounding; group D, the control group without undergoing the wound. The tissues from the wound tract and the surrounding tissues were sampled for bacterial culture and counting. RESULTS: The bacterial counts of the tissues from the wound tract, the tissues within 5 mm and within 5-10 mm from wound tract varied insignificantly between groups A, B and C (P>0.05). In each group, the bacterial counts declined in the tissues as the distance of the sampling sites from the wound tract increased (P<0.01). The bacterial counts of the tissues from the wound tract and within 5 mm from the wound tract in group A, B and C were significantly different from those in group D (P<0.01). CONCLUSION: Hot and humid environment does not significantly affect the bacterial growth in the craniocerebral gunshot wound within the first 6 h, which is a safe period against rapid bacterial growth and suitable for debridement.

Animals↗

PubMed1992

Impact of tropical conditions on thin layer chromatography in analytical toxicology: high temperatures and moderate humidities.

The impact of high temperatures (24 to 39 degrees C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were found to be substantially affected as compared with values obtained at temperate climates. Some TLC systems were more affected than others and the largest deviations of up to 30 Rf units were at low humidities. Tropical conditions also had a negative effect on the reproducibility of Rf values. However, when an Rf-correction procedure was applied, using reference mixtures of known drugs on each plate, accuracy as well as reproducibility of the resulting Rfc values were drastically improved and data thus corrected were found to be compatible with existing TLC data bases developed under moderate climatological conditions. The impact of high to extremely high humidities (70 to 100%) remains to be investigated.

Burkina Faso↗

PubMed2004

[Changes of cat cerebral microcirculation and blood-brain barrier in early stage of craniocerebral gunshot wound in the hot and humid environment].

OBJECTIVE: To study the changes of cat cerebral microcirculation in early stage after craniocerebral gunshot wound in the hot and humid environment to provide laboratory evidence for clinical treatment of such wound. METHODS: Craniocerebral gunshot wound was induced in 24 cats according to the method described by Carey with modifications, and the cats were placed in a cabin with environmental temperature and humidity of 25 degrees Celsius and 50% (group A), and 35 degrees Celsius and 85% (group B), respectively, to observe the changes in all the indices of cerebral microcirculation. RESULTS: All the cats survived and notable changes occurred in the morphology and permeability of cerebral microvascular along with obvious pathological changes in the brain tissue, and the vital signs, hemorheology and blood-brain barrier were significantly different between groups A and B. CONCLUSION: Hot and humid environment induces obvious changes in cat cerebral microcirculation and blood-brain barrier function in the early stages after craniocerebral gunshot wound.

Animals↗

PubMed1991

[Disturbances in the process of hatching of larvae Argas (A) reflexus (Fabr.) (Acari: Ixodida: Argasidae) exposed to various thermal and humidity conditions].

The most cases of abnormal hatch larvae (40.2%) of A. reflexus were in relative humidity 90% and temperature 25 degrees C; the least (0-2.8%)--at the low relative humidity levels (10 and 30%) in all examined temperatures of experiments. The rise of relative humidity caused the greater number of the disturbances of hatch larvae. The most often +non-separation of integument eggs from body of larvae was observed, what made impossible normal formation of legs and made difficult locomotive faculty.

Animals↗

PubMed1976

Effect of temperature and relative humidity on variola virus in crusts.

The viability of variola virus in crusts under different conditions of temperature and relative humidity was studied for 16 weeks. At the ambient temperature of 25.8-26.4 degrees C and 85-90% relative humidity, the virus survived only 8 weeks but at lower temperatures and relative humidities the survival time was considerably prolonged.

Humans↗

PubMed1990

[Characteristics of the relative humidity and temperature in the inspiratory part of the Dräger circle system and their influence on the function of the ciliary epithelium].

Changes in relative humidity and temperature of the anaesthetic gases were measured in the inspiratory limb of the Dräger circle system next to the carbon dioxide absorber in 29 patients requiring ENT surgery under general anaesthesia. Immediately following intubation and prior to extubation, nasal and tracheal cytologic samples were taken with a brush technique and ciliary beat frequency was determined. At a fresh gas flow of 6 l/min, relative humidity increased from 57.6 +/- 1.5 to 62.5 +/- 1.8% (p less than 0.05) after 110 minutes. Temperature increased continuously from 21.96 +/- 0.97 degrees C to 23.83 +/- 0.48 degrees C after 200 minutes. The number of vital ciliated cells in the tracheal samples decreased from 24.4% following induction of anaesthesia to 6% at the end of anaesthesia (p less than 0.05), and from 35.7% to 26.8% (p less than 0.05) in the nasal samples. Ciliary beat frequency remained unchanged at the end of anaesthesia as compared to control in tracheal as well as in nasal samples. It is concluded that the output of relative humidity and temperature in the circle system is not sufficient to prevent broncho-epithelial damage. Ciliary beat automaticity appears to behave according to an all or nothing principle.

Adult↗

PubMed1989

[Drug interactions during storage of mixtures of the antacid group. III. Effect of relative humidity on structural changes in mixtures aluminum hydroxide gel and magnesium hydroxide in the solid phase].

Mixtures of A1(OH)3 gel and Mg(OH)2 were stored for 14 months in the solid phase in chambers with relative air humidity of 35%, 55%, 76% and 92%. IR spectra of the stored mixtures were measured. In mixtures stored at relative air humidity of 35% there were found no changes in IR spectra, while the mixtures stored at relative air humidity of 92% proved to exhibit IR spectra characteristic for hydrotalcite.

Aluminum Hydroxide↗