Effect of hygroscopic fabrics on wear comfort in the fluctuating microclimate of clothing

1. 1. A new type of simulator for clothing microclimate was designed and constructed.

2. 2. The simulator was designed to simulate the humidity fluctuation of clothing microclimate as observed under light working conditions and to measure the surface temperature of sample fabrics against the skin by means of a radiation thermometer.

3. 3. Knitted fabrics of cotton and polyester, and polyethylene films were used as specimens with different hygroscopicities.

4. 4. The quick rise and fall in the surface temperature of cotton fabric was observed under rapid fluctuations of the microclimate humidity.

5. 5. Under the same humidity fluctuations, the temperature of polyester fabric rose and fell more moderately than that of cotton fabrics, and the temperature of the polyethylene film did not change. When the rate of change in stimulus temperature is higher, the threshold temperature of warm sensation of the skin comes closer to a given adaption temperature.

6. 6. Therefore, the rapid and large changes in the fabric temperature against the skin, which were observed especially for hygroscopic cotton fabric, must affect the thermal comfort of clothing.

The physical mechanisms of the perception of dampness in fabrics

1. 1. The detection of dampness in hygroscopic materials has been investigated both by subjective tests and by the application of a model of the physical mechanisms involved.

2. 2. Subjects were asked to rate the degree of dampness of a range of materials of different moisture contents after a short period of contact with the inner forearm.

3. 3. Skin and fabric inner surface temperatures were recorded

4. 4. It was found that highly hygroscopic wool fabrics were perceived as being dryer and maintained a higher temperature at the skin surface than polyester, a less hygroscopic fabric, during fabric-skin contact.

5. 5. A physical model of the sorption/desorption process in hygroscopic materials has been developed from knowledge of fibre sorption kinetics and has been used to study the physical processes which take place at the skin-fabric interface during transient contact.

6. 6. These predictions agree well with the subjective responses and the measured temperatures.

Heat stress and age: Skin blood flow and body temperature

1. 1. The ability to increase skin blood flow is an important mechanism for transferring heat from the body core to the skin for dissipation.

2. 2. During exercise, skin blood flow is typically 20–40% lower in men and women aged 55 and over (compared with 20–30 years old) at a given body core temperature. Yet criterion measures of heat tolerance (changes in core temperature, heat storage) often show minimal or no age-related alterations. From a series of studies conducted in our laboratory over the past 5 years, the following conclusions can be drawn.

3. 3. When fit healthy older subjects are matched with younger subjects of the same gender, size and body composition, V_O2max, acclimation state, and hydration level, age-related differences in skin blood flow are evident. However, these differences often do not translate into “poorer” heat tolerance or higher core temperatures.

4. 4. The larger core-to-skin thermal gradient maintained by the older individuals allows for effective heat transfer at lower skin blood flows.

5. 5. Furthermore, there is an increased coefficient of variation for thermoregulatory response variables with increasing age.

6. 6. Despite differences in the mechanisms underlying thermoregulation, true thermal tolerance is less a function of chronological age than of functional capacity and physiological health status.

7. 7. While this conclusion is based primarily on cross-sectional studies, it is supported by the results of more recent studies using multiple regression analyses.

8. 8. Implicit in this conclusion is the notion that thermal tolerance, at any age, is a modifiable individual characteristic.

Thermal sensations during simultaneous warming and cooling at theh forearm: A human psychophysical study

1. 1.The forearm of 5 female subjects ws thermally stimulated by 2 sets of interposed servo-thermodes that respectively drove skin temperature at ±0.1°C.s⁻¹ for 25 s and then held it constant. Mean skin temperature remained constant. The sequence was repeated at adapting temperatures between 22.5 and 37.5°C.

2. 2.Thermal sensations, continuously reported by the position of a dial, were warmer for heterogeneous thermal stimuli than for homogeneous stimuli when mean skin temperature was greater than 30°C and cooler when less than 27.5°C.

3. 3.This phenomenon is inconsistent with a single additive contribution of “warm” and “cold” information to thermal sensations.

Dynamic heat and moisture transfer through multiple clothing layers

1. 1. The purposes of this study are to find out the arrangement effects on the vapor pressure gradient across the cotton–nylon double layer and to elucidate changes in the vapor pressure gradient when an additional third layer covers the double layer.

2. 2. Model tests for single, double and triple layer system and wear test for triple layer clothing were conducted.

3. 3. It was found that up to the second layer, dryness of innermost microclimate could be maintained when cotton faced the skin (C/N).

4. 4. However, when more permeable and hydrophobic third layer (UWF) covers the double layer, the microclimate of C/N is no longer drier than N/C.

5. 5. When nylon is exposed to the skin, a larger drop in vapor pressure across the first two layers occurred for both model and wear test.

6. 6. The innermost microclimate was not necessarily kept dry when the outermost layer dissipated more moisture due to the inefficient distribution of moisture.

A relationship between heat load and plasma enzyme concentration

1. 1. The sensitivity of serum enzyme levels as indicators of tissue damage is less well established in the prodromal period of heatstroke, especially for sub-lethal stress conditions.

2. 2. Anaesthetized rats were exposed to two different sets of thermal conditions.

3. 3. Plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LD) were assayed in each group upon termination of stress, 6 h post-stress and 24 h post-stress.

4. 4. The tissue “damage” sustained was mild to moderate and completely reversible.

5. 5. The rate of rise in body temperature may constitute an important factor in the ultimate pathology.

6. 6. CK proved to be the most sensitive parameter of tissue “damage”.

A pilot experiment on a method for evaluating acceptability of a daylit luminous environment

1. 1. We propose a hierarchical model as a hypothesis to evaluate comfort in lighting environments.

2. 2. The model consists of physical quantities such as stimuli, and visual sensations as the first response, and then overall evaluation.

3. 3. A pilot experiment in a side-lit classroom usng 147 subjects was made to examine this model.

4. 4. It was found that in the side-lit classroom the most effective answers for discrimination between “acceptable” and “not acceptable” were “the surface of desk was not considered dark” and “not to experience any reflectance of lighting on the sheet of paper on which they wrote”.

5. 5. Moreover all of the effective items relate to the task area, namely desk and blackboard, and this meant that subjects gave priority to workability in the classroom.

Transient response of the human-clothing system

1. 1. A transient clothing model which considers the effects of adsorption and thermal capacitance on the dynamic thermal response of clothing was developed.

2. 2. Moisture adsorption and desorption by the fabric are the major factors that affect the transient response of clothing.

3. 3. This moisture can come from evaporated sweat or from the environment.

4. 4. The clothing model was combined with a modified version of the two-node thermal model of the human body.

5. 5. The combined model shows that, during transients, the mix of latent and sensible heat flow from the skin may differ considerably from the corresponding heat flows from the clothing surface to the environment.

6. 6. The alteration of the heat flows can have a significant impact on the thermal response of the body by changing the sweat rate required to achieve the heat loss necessary to maintain thermal balance.

The high-energy state of the thylakoid system as indicated by chlorophyll fluorescence and chloroplast shrinkage

Certain long-term fluorescence phenomena observed in intact leaves of higher plants and in isolated chloroplasts show a reverse relationship to light-induced absorbance changes at 535 nm (“chloroplast shrinkage”).

1. 1. In isolated chloroplasts with intact envelopes strong fluorescence quenching upon prolonged illumination with red light is accompanied by an absorbance increase. Both effects are reversed by uncoupling with cyclohexylammonium chloride.

2. 2. The fluorescence quenching is reversed in the dark with kinetics very similar to those of the dark decay of chloroplast shrinkage.

3. 3. In intact leaves under strong illumination with red light in CO₂-free air a low level of variable fluorescence and a strong shrinkage response are observed. Carbon dioxide was found to increase fluorescence and to inhibit shrinkage.

4. 4. Under nitrogen, CO₂ caused fluorescence quenching and shrinkage increase at low concentrations. At higher CO₂ levels fluorescence was increased and shrinkage decreased.

5. 5. In the presence of CO₂, the steady-state yield of fluorescence was lower under nitrogen than under air, whereas chloroplast shrinkage was stimulated in nitrogen and suppressed in air.

6. 6. These results demonstrate that the fluorescence yield does not only depend on the redox state of the quencher Q, but to a large degree also on the high-energy state of the thylakoid system associated with photophosphorylation.

Electrical skin resistance and rectal temperature changes in resting human subjects exposed to heat

1. 1.|Fourteen male volunteers were examined under passive heating.

2. 2.|Electrical skin resistance (ESR) and rectal temperature (T_re) were measured during the whole period of exposure.

3. 3.|It was found that:

• —|ESR decreases rapidly with increasing air temperature. Assuming an exponential curve yields a mean time constant of 14 min.

• —|There is a correlation between the individual ESR time constants and T_re increases (r = 0.695, P < 0.005).

• —|Additional changes of ESR were noted in 8 subjects at a constant air temperature of 42°C.

4. 4.|It is concluded that ESR may be a useful indicator of the sweating response of the human thermoregulatory system during exogenous heat load.

The effect of infra-red radiation on rectal temperature and respiration rate of unacclimated female new zealand white rabbits

1. 1.|An experiment was carried out to examine the effects of various levels of infra-red (i.r.) radiation on rectal temperature (RT) and respiration rate (RR) in New Zealand While rabbits.

2. 2.|A 4 × 3 × 6 factorial design was employed in which the factors were: four intensities of i.r. radiant heating of 0.0, 1.9, 2.1 and 2.4 MJ/m²/h, three replicates and six rabbits.

3. 3.|rectal temperature differed (P < 0.05) between treatments and were highest at the “high” level of i.r. radiation (1°C higher than for controls). At the “medium” and “low” levels of i.r. heating RTs were respectively 0.3 and 0.2°C higher than in controls.

4. 4.|At different levels of radiation RR were different (P < 0.05), with the highest (422.7 ± 218.1 breaths/min) at 2.4 MJ/m²/h i.r. radiant heating. This RR was almost 2.5 times that in controls, while at the “low” and “medium” i.r. levels RR values were respectively 1.5 and 2 times those of controls.

How are neuronal thermosensitivity and lack of thermoreception related in the duck's hypothalamus? A tentative answer

1. 1.|In 15 conscious Pekin ducks, 40 “warm sensitive” hypothalamic neurons were identified according to their discharge rates at 40°C T_hy (F₄₀), local temperature coefficients (Δ/ΔT) and Q₁₀.

2. 2.|Q₁₀ and either F₄₀ or ΔF/ΔT were little or not related.

3. 3.|A positive correlation between F₄₀ and ΔF/ΔT was observed which was particularly close (r = 0.94 and 0.96) when the neurons were classified according to their Q₁₀ of <2 and >2.

4. 4.|The results suggest that neurons with positive temperature coefficients in the duck's hypothalamus mostly exhibit linear to exponential temperature-discharge relationships.

5. 5.|This is an contrast to observations on mammalian hypothalamic thermosensitive neurons and may relate to the absence of the thermosensory function in the duck's rostral brainstem.

Autonomic thermoregulatory effects of electrical stimulation of the hypothalamus in the sheep (Ovis aries)

1. 1.|The effects of electrical stimulation of the preoptic region, on autonomic thermoregulatory responses, were studied in conscious sheep at ambient temperatures of 5, 20, and 40°C.

2. 2.|Stimulation of the dorsal preoptic region elicited co-ordinated thermoregulatory responses characterized by increased respiratory frequency (RF), vasodilation of the ears and lowered body temperature. Stimulation inhibited shivering in cold environments.

3. 3.|The thermoregulatory responses were greater at 5°C in unshorn than in shorn sheep. Increased RF, induced at 20 and 40°C, persisted several minutes after stimulation ceased.

4. 4.|Intraventricular injection of noradrenaline reduced both normal and electrically-induced panting.

5. 5.|Sheep would press panels to electrically stimulate the preoptic region and this “self-stimulation” activated heat-loss mechanisms.

Heat death and cellular heat injury

1. 1.|Evidence is presented implicating cellular membranes in cellular heat injury. It is proposed this is the site of the primary lesion.

2. 2.|Secondary and tertiary events, resulting from the primary lesion, cause organism death. Those events may be unique to the life style and grade of organisation of the organism.

3. 3.|Thus hyperthermia may cause “excessive” fluidisation of membranes and so cause impairment of membrane permeability and disrupt the stability of membrane enzymes.

4. 4.|Homeoviscous adaptation of membrane fluidity may well have an important role in resistance acclimation as well as resistance adaptation.

An experimental study of effects of low-level sound in our daily life on a mental task

1. 1. It is often reported that any sound from the neighborhood disturbs one's reading or study, even though it is at a low level.

2. 2. This study was done to clarify the mechanism by which the low level sound in our daily life exerts an influence upon mental tasks.

3. 3. Two experiments were carried out, one by an ordinary, and the other by a social psychological test. In both, a random number generation test was applied as the mental exercise. The levels of presented sounds in each condition were 34–45 dBA in Leq.

4. 4. One of various conditions was in conformity with a setting of“low level noise”, where existence of low level sound is not recognized as an inevitable phenomenon but perceived as the noise.

5. 5. The quality of performance tends to be worse, though the quantitative side can be maintained.

Effect of cycloheximide on nonpermissive temperature killing in tsH1 mutant cells

1. 1.|We investigated the mechanism of cycloheximide-induced heat protection. We proposed a hypothesis to account for the mechanism [Lee and Dewey (1986) Radiat. Res. 106, 98–110].

2. 2.|Cycloheximide protects cells from hyperthermic killing by means of protecting thermolabile proteins from denaturation.

3. 3.|For this study, we have employed temperature-sensitive mutant tsH1 which contains a thermolabile leucyl-tRNA synthetase.

4. 4.|By 15 h of incubation at the nonpermissive temperature of 39.5 or 40°C, 40 or 93% of mutant cells respectively, were killed. In contrast, wild type SC cells did not lose viability after this same incubation.

5. 5.|Although killing of tsH1 by incubation at the nonpermissive temperatures was mainly due to denaturation of a thermolabile leucyl-tRNA synthetase, cycloheximide did not protect mutant cells from killing. However, tsH1 and SC cells exhibited similar sensitivities to killing at 43°C and above. Furthermore, cycloheximide protected both cell types from hyperthermic killing.

6. 6.|There was a 200- or 700-fold increase in survival after 2.5 h at 43°C by treatment with cycloheximide in tsH1 or SC cell type, respectively. Thus, the cellular target(s) for hyperthermic killing at this temperature apparently are similar in both types of cells.

7. 7.|The data indicate that the mechanism behind cycloheximide-induced heat protection is probably not the prevention of protein denaturation.

Investigations on the surveys of office environments and the total evaluation method—IAQ-Index

1. 1. A comprehensive study was made to establish evaluation methods for better office environments.

2. 2. In our study, measurements of thermal, acoustic, lighting, airflow and air quality conditions in indoor environments were made as well as questionnaire to the occupants on the evaluations of indoor environments and the feeling of fatigue.

3. 3. We also made an attempt to rate the evaluation value based on concepts and standards to evaluate totally office environments in a view point of “the office environments where people can work healthy and vigorously”. The evaluation values were called IAQ-index.

The effects of wind and thermal radiation on thermal responses during rest and exercise in a cold environment

1. 1. The purpose of this study was to investigate the effects of thermal radiation and wind on thermal responses at rest and during exercise in a cold environment.

2. 2. The experimental conditions were radiation and wind (R + W), no radiation and wind (W), radiation and no wind (R), no radiation and no wind (C).

3. 3. The air temperature was −5°C. Thermal radiation was 360 W/m². Air velocities were 0.76, 1.73 and 2.8 m/s. Rectal and skin temperatures, heart rate and oxygen consumption were recorded. Thermal and comfort sensations were questioned.

4. 4. There are no significant effects of thermal radiation and wind on the physiological responses except the mean skin temperature. There are significant effects on the mean skin temperature (P < 0.01) and thermal sensation (P < 0.05).

Lactate modeling and its application to endurance training

1. 1. In this short review, previous studies regarding the modeling of lactate (La) response to exercise and its application to endurance training have been summarized.

2. 2. Additionally the result of a recent study by the present authors are shown.

3. 3. Several models for La response to step and ramp exercise are already proposed and deductions derived from them are used for practical purposes such as the prediction of race performance in middle-and long-distance runners as well as for construction of their training regimens.

4. 4. Only a limited number of models however have tried to quantify whole body La kinetics to exercise in humans concomitantly with describing physiological mechanisms underlying the observed phenomenon.

5. 5. In a recent study described further in this paper a 2 compartment model was used for the purpose of clarifying the current “La production vs degradation” controversy during La adaptation to training.

6. 6. It was determined from this investigation that the La metabolic clearance rate during recovery is enhanced by the endurance training.

7. 7. This is in accordance with another recent observation of an increased La metabolic clearance rate at high absolute work rates and all relative work rates during exercise.