Combining thermal model and kinetics: Implications in dynamic simulation of anaerobic digesters.

In this study, ADM1-based kinetics were combined with a thermal model that accounts for various heat transfers inside and through the reactor's boundaries. Computing the energy of bioreactions based on kinetic rates prevented an overestimation of approximately 20% in the heat demand of the heat exchanger, compared to calculations using feedstock degradation heat. This also improved the representation of the digester's thermal and reactional inertia. Simulations across different climates demonstrated the necessity to tailor digester construction. In the North West United Kingdom, biogas auto-consumption was 23% higher than that of the same reactor in South West France. Enhancing the thermal insulation of the digester reduced heat losses by 37% in the United Kingdom. Therefore, coupling the kinetic and thermal models expands the insights that can be extracted from simulations, which can be valuable in optimizing the operation and design of biogas digesters.

Constructing Thermal Convection Film for Low Heat Loss and High Salt Resistance in Wood-Based Solar Evaporators.

Unique suspension solar evaporator is one of the effective measures to address the major bottleneck of the emerging interfacial evaporators, i.e., the accumulation of salts on the surface. Yet, it remains a considerable challenge to avoid substantial heat loss underwater. Herein, a suspension wood-based evaporator is proposed with a thermal convection structure that effectively balances the contradiction between salt-resistance ability and heat loss. Benefitting from the heat centralization due to thermal convection, such suspension evaporator exhibits an excellent steam generation rate, which increases from 1.23 to 1.63 kg m-2 h-1 compared to the conventional suspension evaporator. Simultaneously, the steam generation rate retention improves from 64.9% over 20 test cycles to nearly 100% compared to the interfacial evaporator. This work provides an effective pathway for exploring efficient and stable suspension evaporators, offering essential directions for the future development and application of solar-driven evaporation technologies.

Detrimental effects of scene manipulations on temperature-based time since death estimation.

In forensic casework, time since death (TSD) estimations may play a crucial role to establish chains of events as well as for alibi assessment in homicide cases. Classical TSD estimation relies on reasonably stable ambient temperatures and a correct documentation of ambient and rectal temperatures. This constancy is in some cases disturbed by post-discovery alterations of the crime scene, e.g. opening a window. In order to develop a better understanding of this alteration-based detrimental impact on TSD estimation as well as to identify feasible recommendations for casework, the present pilot study examined ambient temperature effects of different window opening scenarios regarding various time intervals (5 to 360 min) in a furnished 10 m2 apartment during winter. In this context, in addition to the ambient temperature and thus the cooling rate of the room, re-approximation to initial room temperature, potential influences on a nomogram-based time since death estimation using a fictitious case, and the impact of the measurement height above the ground were investigated. Our data indicate a significant reduction of the mean temperature decrease rate after 15 min regardless of the remaining opening time and a correlation with the size of the respective opening surfaces. Re-approximation to initial room temperatures was observed with up to three times longer than the initial opening time. There was no evidence of a substantial advantage of temperature measurements above the level of the corpse (> 0.1 m). The limitations of the study and its applicability for forensic casework are critically reviewed.

Influence of fentanyl, medetomidine-fentanyl or acepromazine-fentanyl premedication on oesophageal and rectal temperature in dogs under anaesthesia.

OBJECTIVE: To compare changes in oesophageal (T-Oeso) and rectal (T-Rec) temperature in dogs during general anaesthesia and premedicated with fentanyl, medetomidine-fentanyl or acepromazine-fentanyl. STUDY DESIGN: Prospective, randomized, blind clinical study. ANIMALS: A total of 120 healthy dogs, aged 2-10 years and weighing 5-20 kg. METHODS: Dogs were randomly allocated to one of three groups. Animals of F group were premedicated with fentanyl (0.01 mg kg-1), MF group with medetomidine (0.005 mg kg-1) and fentanyl (0.01 mg kg-1) and AF group with acepromazine (0.01 mg kg-1) and fentanyl (0.01 mg kg-1). Anaesthesia was induced with propofol and maintained with isoflurane in oxygen-air mixture. Fentanyl was administered continuously (0.01 mg kg-1 hour-1). The T-Oeso, T-Rec and ambient temperatures were recorded after induction (T0) and subsequently at 10 minute intervals for 60 minutes (T10-T60). Data were analysed using anova or their non-parametric equivalents (p < 0.05). RESULTS: Median T-Oeso was significantly higher in MF group between T0-T20 compared with other groups. Median T-Oeso significantly decreased in F group from 38.0 °C (T0) to 37.4 °C (T30), 37.1 °C (T40), 36.9 °C (T50) and 36.6 °C (T60), in MF group from 38.3 °C (T0) to 37.7 °C (T30), 37.5 °C (T40), 37.2 °C (T50) and 37.1 °C (T60) and in AF group from 37.7 °C (T0) to 37.3 °C (T40), 37.2 °C (T50) and 37.1 °C (T60). The T-Rec significantly decreased in F group from 38.0 °C (T0) to 37.4 °C (T40), 37.2 °C (T50) and 36.9 °C (T60), in MF group from 38.3 °C (T0) to 37.5 °C (T50) and 37.4 °C (T60) and in AF group from 38.2 °C (T0) to 37.6 °C (T40), 37.5 °C (T50) and 37.4 °C (T60). CONCLUSIONS AND CLINICAL RELEVANCE: Premedication with fentanyl, medetomidine-fentanyl or acepromazine-fentanyl in the doses used decreased the T-Oeso and T-Rec. The T-Oeso at the beginning of anaesthesia was higher after premedication with medetomidine-fentanyl. However, this difference was not clinically significant.

Exercise intensity- and body region-specific differences in sweating in middle-aged to older men with and without type 2 diabetes.

Type 2 diabetes (T2D) is associated with reduced whole body sweating during exercise-heat stress. However, it is unclear if this impairment is related to exercise intensity and whether it occurs uniformly across body regions. We evaluated whole body (direct calorimetry) and local (ventilated-capsule technique; chest, back, forearm, thigh) sweat rates in physically active men with type 2 diabetes [T2D; aged 59 (7) yr; V̇o2peak 32.3 (7.6) mL·kg-1·min-1; n = 26; HbA1c 5.1%-9.1%] and without diabetes [Control; aged 61 (5) yr; V̇o2peak 37.5 (5.4) mL·kg-1·min-1; n = 26] during light- (∼40% V̇o2peak), moderate- (∼50% V̇o2peak), and vigorous- (∼65% V̇o2peak) intensity exercise (elicited by fixing metabolic heat production at ∼150, 200, 250 W·m-2, respectively) in 40°C, ∼17% relative humidity. Whole body sweating was ∼11% (T2D: Control mean difference [95% confidence interval]: -37 [-63, -12] g·m-2·h-1) and ∼13% (-50 [-76, -25] g·m-2·h-1) lower in the T2D compared with the Control group during moderate- and vigorous- (P ≤ 0.001) but not light-intensity exercise (-21 [-47, 4] g·m-2·h-1; P = 0.128). Consequently, the diabetes-related reductions in whole body sweat rate were 2.3 [1.6, 3.1] times greater during vigorous relative to light exercise (P < 0.001). Furthermore, these diabetes-related impairments in local sweating were region-specific during vigorous-intensity exercise (group × region interaction: P = 0.024), such that the diabetes-related reduction in local sweat rate at the trunk (chest, back) was 2.4 [1.2, 3.7] times greater than that at the limbs (thigh, arm). In summary, when assessed under hot, dry conditions, diabetes-related impairments in sweating are exercise intensity-dependent and greater at the trunk compared with the limbs.NEW & NOTEWORTHY This study evaluates the influence of exercise intensity on decrements in whole body sweating associated with type 2 diabetes. Furthermore, it investigates whether diabetes-related sweating impairments were exhibited uniformly or heterogeneously across body regions. We found that whole body sweating was attenuated in the type 2 diabetes group relative to control participants during moderate- and vigorous-intensity exercise but not light-intensity exercise; impairments were largely mediated by reduced sweating at the trunk rather than the limbs.

Animal design advantage from the analogy between friction and body heat loss.

When a fluid accelerates as it sweeps a solid surface there are two consequences: the friction and the heat transfer (thermal contact) between fluid and solid increase simultaneously. This is known as the universal analogy between fluid friction and heat transfer. In thermal engineering these two effects are problematic because improved thermal contact is beneficial, and increased friction (i.e., pumping power) is detrimental to overall performance. In the present article we question whether the 'analogy' between these conflicting effects hampers the performance of animal movement. The theory focuses on warm-blooded swimmers and the effects (friction, heat transfer) that result from one change in the configuration of the body. Selected for analysis is a breaststroke swimmer. During gliding while reaching forward the 'one change' is from (a) legs spread apart, to (b) legs held tight together. The theory shows that the change from (a) to (b) has two consequences: greater swimming speed, and reduced body heat loss. In animal design both effects are beneficial, unlike in engineered flow systems. The analogy between fluid friction and heat transfer accelerated the evolution of animal design, and accounts for the 'divergent evolution' of fish and mammals.

How birds dissipate heat before, during and after flight.

Animal flight uses metabolic energy at a higher rate than any other mode of locomotion. A relatively small proportion of the metabolic energy is converted into mechanical power; the remainder is given off as heat. Effective heat dissipation is necessary to avoid hyperthermia. In this study, we measured surface temperatures in lovebirds (Agapornis personatus) using infrared thermography and used heat transfer modelling to calculate heat dissipation by convection, radiation and conduction, before, during and after flight. The total non-evaporative rate of heat dissipation in flying birds was 12× higher than before flight and 19× higher than after flight. During flight, heat was largely dissipated by forced convection, via the exposed ventral wing areas, resulting in lower surface temperatures compared with birds at rest. When perched, both before and after exercise, the head and trunk were the main areas involved in dissipating heat. The surface temperature of the legs increased with flight duration and remained high on landing, suggesting that there was an increase in the flow of warmer blood to this region during and after flight. The methodology developed in this study to investigate how birds thermoregulate during flight could be used in future studies to assess the impact of climate change on the behavioural ecology of birds, particularly those species undertaking migratory flights.

Innovative Metabolic Rate Sensing Approach for Probing Human Thermal Comfort.

The human metabolic rate has attracted increasing interest as it is the most critical parameter in thermal comfort evaluation, a challenging field, while it is always determined imprecisely. The main issue hampering metabolic rate portable measurement is a lack of reliable methods. Current measuring solutions are unsatisfactory because nonportable bulky size systems and disturbance masks are required. This paper proposes a novel metabolic rate measurement model, which we believe is the first of its kind, to accurately identify and predict human metabolism values via wearable technology. Based on a newly developed theory, the designed wearable metabolic rate sensor was fabricated to measure key parameters: heart rate, heat loss, and skin resistance. Together with the body muscle rate, the new final linear metabolic rate model showed easy prediction capability. Eight volunteers were invited for the experiment under three conditions under four activity intensity states. First, the results significantly verify that a linear relationship exists between the metabolic rate tested by the Quark CPET instrument and our proposed model, with a high coefficient of determination (R2 ≈ 0.90). The correlation model is worth mentioning because it coincides with our hypothesis, with at least 95% overall accuracy and less than 2% uncertainty under each condition. Second, the most remarkable finding is that our model is exceedingly suitable (R2 ≈ 0.90) for the same person, regardless of the experimental temperature. Finally, validation is conducted in a wider metabolic range, further strengthening confidence in our metabolic rate estimation approach. In summary, based on an innovative methodology, our novel metabolic rate sensor is wearable, comfortable, real-time achievable, and miniaturized compared with the existing equipment. This paper sheds new light on human metabolic rate measurement and prediction. Furthermore, our approach and designed sensor can be applied to evaluate indoor thermal comfort precisely, thus leading to reduced energy consumption.

The impact of thermal insulating materials in heat loss control in smart green buildings using experimental and swarm intelligent analysis.

The efficacy of saving energy standards depends on the ability to anticipate the heat loss of buildings. Environmentally friendly materials, also known as eco-friendly or sustainable materials, have a minimal negative impact on the environment throughout their life cycle. These materials are designed to conserve resources, reduce pollution, and promote sustainability. The characteristics of non-stationary and non-linear heat loss through environmentally friendly materials make it challenging to anticipate accurately. At the same time, many of the industry's presently accessible computational models have been created with this in mind; the majority call for powerful computers and time-consuming computations. The artificial neural network (ANN) has been utilized for prediction, and ground-breaking research has shown the viability of this strategy. This research proposes an artificial neural network (ANN) prototype to estimate construction cooling load usage. ANN is integrated with the vortex search algorithm (VS), stochastic fractal search (SFS), and multi-verse optimizer (MVO) models to compare the three models' outcomes and suggest a more accurate strategy. These techniques make a linear mapping among the output and input parameters, often utilized for modeling and regression. The value of the multiple determination coefficient is also determined. The values of the training R2 (coefficient of multiple determination) are 0.9464, 0.99827, and 0.99522 for VS-MLP, SFS-MLP, and MVO-MLP, respectively, with an unknown dataset which is acceptable. The training RMSE amounts for VS-MLP, SFS-MLP, and MVO-MLP are 0.06433, 0.00619, and 0.01028 for the unknown dataset, which is acceptable. According to the MAE values of 0.0082902, 0.0047834, and 0.0076534 in the training phase for VS-MLP, SFS-MLP, and MVO-MLP approaches and the values of testing MAE error of 0.029107, 0.018167, and 0.029212 for VS-MLP, SFS-MLP, and MVO-MLP approaches, respectively, it is obtained that the SFS-MLP has a lower MAE value. The lowest RMSE value and the higher R2 value indicate the favorable accuracy of the SFS-MLP technique.

Transdermal iontophoretic application of l-NAME is available in sweating research induced by heat stress in young healthy adults.

Iontophoretic transdermal administration of NG-nitro-l-arginine methyl ester hydrochloride [l-NAME, a nitric oxide synthase (NOS) inhibitor] has been used as a non-invasive evaluation of NOS-dependent mechanisms in human skin. However, the availability has yet to be investigated in sweating research. Prior observations using invasive techniques (e.g., intradermal microdialysis technique) to administer l-NAME have implicated that NOS reduces sweating induced by heat stress but rarely influences the response induced by the administration of cholinergic muscarinic receptor agonists. Therefore, we investigated whether the transdermal iontophoretic administration of l-NAME modulates sweating similar to those prior observations. Twenty young healthy adults (10 males, 10 females) participated in two experimental protocols on separate days. Before each protocol, saline (control) and 1% l-NAME were bilaterally administered to the forearm skin via transdermal iontophoresis. In protocol 1, 0.001% and 1% pilocarpine were iontophoretically administered at l-NAME-treated and untreated sites. In protocol 2, passive heating was applied by immersing the lower limbs in hot water (43 °C) until the rectal temperature increased by 0.8 °C above baseline. The sweat rate was continuously measured throughout both protocols. Pilocarpine-induced sweat rate was not significantly different between the control and l-NAME-treated sites in both pilocarpine concentrations (P ≥ 0.316 for the treatment effect and interaction of treatment and pilocarpine concentration). The sweat rate during passive heating was attenuated at the l-NAME-treated site relative to the control (treatment effect, P = 0.020). Notably, these observations are consistent with prior sweating studies administrating l-NAME into human skin using intradermal microdialysis techniques. Based on the similarity of our results with already known observations, we conclude that transdermal iontophoresis of l-NAME is a valid non-invasive technique for the investigation of the mechanisms of sweating related to NOS during heat stress.

Impermeable Graphene Skin Increases the Heating Efficiency and Stability of an MXene Heating Element.

A Joule heater made of emerging 2D nanosheets, i.e., MXene, has the advantage of low-voltage operation with stable heat generation owing to its highly conductive and uniformly layered structure. However, the self-heated MXene sheets easily get oxidized in warm and moist environments, which limits their intrinsic heating efficiencies. Herein, an ultrathin graphene skin is introduced as a surface-regulative coating on MXene to enhance its oxidative stability and Joule heating efficiency. The skin layer is deposited on MXene using a scalable solution-phased layer-by-layer assembly process without deteriorating the excellent electrical conductivity of the MXene. The graphene skin comprises narrow and hydrophobic channels, which results in ≈70 times higher water impermeability of the hybrid film of graphene and MXene (GMX) than that of the pristine MXene. A complementary electrochemical analysis confirms that the graphene skin facilitates longer-lasting protection than conventional polymer coatings owing to its tortuous pathways. In addition, the sp2 planar carbon surface with a low heat loss coefficient improves the heating efficiency of the GMX, indicating that this strategy is promising for developing adaptive heating materials with a tractable voltage range and high Joule heating efficiency.

Experimental Study on Spread and Burning Characteristics of Continuous Spill Fire Leaked from a Point Source under Different Slopes.

Liquid fuel is widely used in industry and transportation. Liquid fuel leakage usually results in some spill fire accidents. In this paper, the effect of slope on the spread and burning behaviors of continuous spill fire from a point discharge source was studied by experiments. The flame spread rate, burning rate, heat convection at the bottom surface, flame feedback radiation, and flame height were analyzed. The results show that the spread area has an increasing trend with the slope, and the length of the spread area increases obviously, while the width of spread area shows an opposite trend. Moreover, the burning rate and the flame height of the steady stage decreases significantly with the slope increase, which can be attributed to the increase of heat convection between the fuel layer and bottom for the larger slopes. Subsequently, a burning rate model for the steady stage is built considering fuel layer heat loss and validated by the current experimental data. This work can provide guidance for the thermal hazard analysis of liquid fuel spill fires from a point source.

Evaporative water loss from dairy cows in climate-controlled respiration chambers.

The effects of ambient temperature (AT) on total evaporative water loss from dairy cows at different relative humidity (RH) and air velocity (AV) levels were studied. Twenty Holstein dairy cows with an average parity of 2.0 ± 0.7 and body weight of 687 ± 46 kg participated in the study. Two climate-controlled respiration chambers were used. The experimental indoor climate was programmed to follow a diurnal pattern with AT at night being 9°C lower than during the day. Night AT was gradually increased from 7 to 21°C and day AT was increased from 16°C to 30°C within an 8-d period, both with an incremental change of 2°C/d. The effect of 3 RH levels with a diurnal pattern were studied as well, with low values during the day and high values during the night: low (day, 30%; night, 50%), medium (day, 45%; night, 70%), and high (day, 60%; night, 90%). The effects of AV were studied during the daytime at 3 levels: no fan (0.1 m/s), fan at medium speed (1.0 m/s), and fan at high speed (1.5 m/s). The medium and high AV levels were only combined with medium RH. In total, there were 5 treatments with 4 replicates each. The animals had free access to feed and water. Based on the water balance principle inside the respiration chambers, the total evaporative water loss from dairy cows at a daily level was quantified by measuring the mass of water in the incoming and outgoing air, condensed water, added water from a humidifier, and evaporative water from a wet floor, drinking bowl, manure reservoir, and water bucket. Water evaporation from a sample skin area was measured with a ventilated skin box, and water evaporation, through respiration with a face mask. The results show that RH/AV levels had no significant effect on total evaporative water loss, whereas the interaction effect between RH/AV with AT was significant. Cows at a high RH had a tendency for a lower increasing rate of evaporative water loss compared with cows at a low RH (0.61 vs. 0.79 kg/d per 1°C increase of AT). Cows at medium and high AV levels had a greater increasing rate than cows at low AV (0.91 and 0.95 vs. 0.71 kg/d per 1°C increase of AT, respectively). The increase of evaporative heat loss from dairy cows was mainly a result of the increase in evaporation (of sweat) from the skin. The skin water evaporation determined with the water balance method (less evaporation from respiration) and the ventilated skin box method showed no significant difference. The implication of this study is that cows at a high AT depend mainly on evaporative cooling from the skin. The ventilated skin box method, measuring only a small part of the skin during a short period during the day, can be a convenient and accurate way to determine the total cutaneous evaporative water loss from cows.

Induction and decay of seasonal acclimatization on whole body heat loss responses during exercise in a hot humid environment with different air velocities.

Whether whole body heat loss and thermoregulatory function (local sweat rate and skin blood flow) are different between summer and autumn and between autumn and winter seasons during exercise with different air flow in humid heat remain unknown. We therefore tested the hypotheses that whole body sweat rate (WBSR), evaporated sweat rate, and thermoregulatory function during cycling exercise in autumn would be higher than in winter but would be lower than in summer under hot-humid environment (32 C, 75% RH). We also tested the hypothesis that the increase of air velocity would enhance evaporated sweat rate and sweating efficiency across winter, summer, and autumn seasons. Eight males cycled for 1 h at 40% V̇o2max in winter, summer, and autumn seasons. Using an electric fan, air velocity increased from 0.2 m/s to 1.1 m/s during the final 20 min of cycling. The autumn season resulted in a lower WBSR, unevaporated sweat rate, and a higher sweating efficiency compared with summer (all P ≤ 0.05) but WBSR and unevaporated sweat rate in autumn were higher than in winter and thus sweating efficiency was lower when compared with winter only at the air velocity of 0.2 m/s (All P ≤ 0.05). Furthermore, evaporated sweat rate and core temperature (Tcore) were not different among winter, summer, and autumn seasons (All P > 0.19). In conclusion, changes in WBSR across different seasons do not alter Tcore during exercise in a hot humid environment. Furthermore, increasing air velocity enhances evaporated sweat rate and sweating efficiency across all seasons.

Relationship between heat loss indexes and physiological indicators of turnout-related heat strain in mild and hot environments.

A validated physiological manikin method was used to qualify environmentally dependent correlations between firefighter turnout total heat loss (THL) and intrinsic evaporative resistance (Ref) heat strain indexes and core temperature rise in stressful work conducted in mild (25 °C, 65% relative humidity [RH]) and hot (35 °C, 40% RH; 40 °C, 28% RH) conditions. Five turnout suit constructions representing a wide range of breathability were selected. The observed correlations between measured material heat loss and core temperature showed that the THL heat strain index accurately forecast thermal burden in mild environments (<25 °C); while the Ref index provided accurate prediction in hot environments (>35 °C). They showed that the THL index did not predict heat strain in hot work environments. The findings of this study support incorporating both the Ref and THL heat strain indexes as dual metrics for characterizing the heat strain performance of turnout clothing fabrics.

Environmental, economic, and performance assessment of solar air heater with inclined and winglet baffle.

To investigate the solar air heater's (SAH) effectiveness, experiments are conducted using flat plate and artificially roughened plate in terms of inclined and winglet baffles over the collector surface. This proposed system collector plate is made up of inclined and winglet ribs and serves as an artificial roughness generator. Air stream of 0.01, 0.02, and 0.03 kg/s are used in the experiment. To determine the improvement in the proposed work, these experimental results are compared with flat plate SAH. This proposed work offers a greater efficiency, useful energy gain, and lower top heat loss than a conventional SAH. At 0.03 kg/s system efficiency and useful energy gain reach their peak. Experimental day's average efficiency of a SAH with inclined and winglet baffles is 30.8%, 52.7%, and 72.9%, respectively, for the examined cases, and it is 11%, 13.8%, and 22.2% more effective than a flat surface SAH. For the investigated air flow rates, the proposed system gains 36.2%, 24.2%, and 28.9% more energy than flat plate SAH. Substantial reductions in top losses of up to 8.48%, 7.28%, and 7.27% have been reported at the specified flow rates, respectively. Energy metrics and economic study performed show the payback time, production factor, life cycle conversion efficiency, and economic values of the proposed SAH are optimum.

Effect of cold ambient temperature on heat flux, skin temperature, and thermal sensation at different body parts in elite biathletes.

Introduction: When exercising in the cold, optimizing thermoregulation is essential to maintain performance. However, no study has investigated thermal parameters with wearable-based measurements in a field setting among elite Nordic skiers. Therefore, this study aimed to assess the thermal response and sensation measured at different body parts during exercise in a cold environment in biathletes. Methods: Thirteen Swiss national team biathletes (6 females, 7 males) performed two skiing bouts in the skating technique on two consecutive days (ambient temperature: -3.74 ± 2.32 °C) at 78 ± 4% of maximal heart rate. Heat flux (HF), core (Tcore) and skin (Tskin) temperature were measured with sensors placed on the thigh, back, anterior and lateral thorax. Thermal sensation (TS) was assessed three times for different body parts: in protective winter clothing, in a race suit before (PRE) and after exercise (POST). Results: HF demonstrated differences (p < 0.001) between sensor locations, with the thigh showing the highest heat loss (344 ± 37 kJ/m2), followed by the back (269 ± 6 kJ/m2), the lateral thorax (220 ± 47 kJ/m2), and the anterior thorax (192 ± 37 kJ/m2). Tcore increased (p < 0.001). Tskin decreased for all body parts (p < 0.001). Thigh Tskin decreased more than for other body parts (p < 0.001). From PRE to POST, TS of the hands decreased (p < 0.01). Conclusion: Biathletes skiing in a race suit at moderate intensity experience significant heat loss and a large drop in Tskin, particularly at the quadriceps muscle. To support the optimal functioning of working muscles, body-part dependent differences in the thermal response should be considered for clothing strategy and for race suit design.

Thermoregulation during a six-hour exposure to warm, humid hyperbaric conditions.

Purpose: In a disabled submarine scenario, a pressurized rescue module (PRM) may be deployed to rescue survivors. If the PRM were to become disabled, conditions could become hot and humid exposing the occupants to heat stress. We tested the hypothesis that the rise in core temperature and fluid loss from sweating would increase with rising dry bulb temperature. Methods: Twelve males (age 22 ± 3 years; height 179 ± 7 cm; mass 77.4 ± 8.3 kg) completed this study. On three occasions, subjects were exposed to high humidity and either 28-, 32-, or 35˚C for six hours in a dry hyperbaric chamber pressurized to 6.1 msw. Changes in core temperature (Tc) and body mass were recorded and linear regression lines fit to estimate the predicted rise in Tc and loss of fluid from sweating. Results: Heart rate was higher in the 35°C condition compared to the 28°C and 32°C conditions. Tc was higher in the 32°C condition compared to 28°C and higher in 35°C compared to the 28˚°C and 32°C conditions. Projected fluid loss in all of the tested conditions could exceed 6% of body mass after 24 hours of exposure endangering the health of sailors in a DISSUB or disabled PRM. A fluid intake of 1.0 to 3.5 L would be required to limit dehydration to 2% or 4% of initial mass depending upon condition. Conclusions: Prolonged exposure to 35°C conditions under pressure results in uncompensable heat stress. 32°C and 35°C exposures were compensable under these conditions but further research is required to elucidate the effect of increased ambient pressure on thermoregulation.

In Situ Activation of Superhydrophobic Surfaces with Triple Icephobicity at Low Temperatures.

Superhydrophobic surfaces have been widely studied due to their potential applications in aerospace fields. However, superhydrophobic surfaces with excellent water-repellent, anti-icing, and icephobic performances at low temperatures have rarely been reported. Herein, superhydrophobic surfaces with heating capability were prepared by etching square micropillar arrays on the surface of multiwalled carbon nanotube (MWCNT)/poly(dimethylsiloxane) (PDMS) films. The fabricated superhydrophobic surface has triple icephobicity, which can be activated even at low temperatures. The triple icephobicity is triggered by an applied voltage to achieve excellent water-repellent and icephobic capabilities, even at -40 °C. Additionally, theoretical calculations reveal that a droplet on a superhydrophobic surface loses heat at a rate of 8.91 × 10-5 J/s, which is 2 orders of magnitude slower than a flat surface (2.15 × 10-3 J/s). Also, at -40 °C, the mechanical interlocking force formed between the superhydrophobic surface and ice can be released by the heating property of the superhydrophobic surface. This low-energy, multifunctional superhydrophobic surface opens up new possibilities for bionic smart multifunctional materials in icephobic applications.

Influence of Heat Exposure on Motor Control Performance and Learning as Well as Physiological Responses to Visuomotor Accuracy Tracking Task.

This study aimed to determine whether heat exposure attenuates motor control performance and learning, and blunts cardiovascular and thermoregulatory responses to visuomotor accuracy tracking (VAT) tasks. Twenty-nine healthy young adults (22 males) were divided into two groups performing VAT tasks (5 trials × 10 blocks) in thermoneutral (NEUT: 25 °C, 45% RH, n = 14) and hot (HOT: 35 °C, 45% RH, n = 15) environments (acquisition phase). One block of the VAT task was repeated at 1, 2, and 4 h after the acquisition phase (retention phase). Heat exposure elevated skin temperature to ~3 °C with a marginally increased core body temperature. VAT performance (error distance of curve tracking) was more attenuated overall in HOT than in NEUT in the acquisition phase without improvement in magnitude alteration. Heat exposure did not affect VAT performance in the retention phase. The mean arterial blood pressure and heart rate, but not for sweating and cutaneous vascular responses to VAT acquisition trials, were more attenuated in HOT than in NEUT without any retention phase alternations. We conclude that skin temperature elevation exacerbates motor control performance and blunts cardiovascular response during the motor skill acquisition period. However, these alternations are not sustainable thereafter.