Thermal Skin Research Articles

Experimental Study on the Effect of Temperature Up-Step on Human Thermal Perception and Skin Temperature between Activity Intensities at Low Ambient Temperatures

In the north of China, during winter, a large number of activities (such as leisure, work, sightseeing and sports) are engaged in. This paper mainly focuses on human thermal perceptions of outdoor activities in a winter climate, especially the change in thermal perceptions when humans enter a temporary rest space with a shelter effect. A climate chamber was applied in our experiments, and temperature up-steps of 4, 8 and 12 °C were set, respectively. Twenty four college students were invited to engage in activities of different intensities, such as standing, walking (slowly) and biking. Through questionnaire survey and field measurement, the subjects’ thermal sensation, thermal comfort and skin temperature were obtained. Hypothesis testing and non-linear regression methods were introduced to analyze experiment data. Major results were as follows. After temperature up-step changes, thermal sensation and skin temperature reach steady state within 30 min. However, the change in skin temperature caused by a short-term thermal experience does not disappear completely within 40 min. In addition to the influence of ambient temperature changes, activity intensity also influenced the variation in thermal sensation (subjective) and skin temperature (objective). These study results provide a scientific reference for future research and design of a temporary rest space in low ambient temperatures. Experimental studies including broader age groups and outdoor field tests are valuable for future research.

Well and reservoir characterization using combined temperature and pressure transient analysis: A case study

Significant temperature variations are measured in oil and gas production wells with large pressure drawdown such as high production rate wells and tight formations. The considerable heating or cooling effects in the wellbore sandface invalidates the assumption of isothermal fluid flow in porous media. While this assumption satisfies most of the classic reservoir engineering analyses, the potential of slight thermal effects are attracting extensive interest and numerous thermal models have been proposed recently.The pitfalls and weaknesses of pressure transient analysis have been extensively investigated since 1930's which is still persistence despite developments of more accurate analytical and numerical models. Some of the weaknesses are rooted in the assumption of isothermal fluid flow in well test analysis methods.In this paper, we show the power and added value of combining temperature transient analysis to complement pressure transient analysis. Interestingly, the characteristics of skin effect such as radius and permeability of the damaged zone can be determined from temperature measurements. We study various parameters such as rock and fluid heat capacity, rock thermal conductivity, rock porosity, rock permeability and skin properties to illustrate the effect of each parameter on wellbore temperature data and hence the application of TTA for reservoir characterization. Using an accurate thermal flow mode, a case study has been done to investigate the importance of temperature transient analysis to better characterize an oil field well.

Evaluation of the feasibility of using skin temperature to predict overall thermal sensation in non-uniform thermal environments

Skin temperature is an important physiological parameter that reflects human thermal sensation. However, it is uncertain whether it can evaluate overall thermal sensation in non-uniform thermal environments. This study aims to explore the feasibility of using skin temperature to predict overall thermal sensation in non-uniform environments. The overall thermal sensation votes and skin temperatures were obtained in a non-uniform thermal environment with local cooling on the chest in a climate chamber. The predictive power of the representative skin temperature (RST) estimated from five different methods was examined by analysing its sensitivity and the correlation between the overall thermal sensation and the RST. The RSTs estimated from the 7-point method with the measurement site of trunk assigned on the chest and the 1-point method with a measurement site at the centre of the chest had high sensitivity and coefficients of determination. They could reflect overall thermal sensation in the non-uniform environments with local cooling on the chest. The results imply that skin temperature could be used to evaluate overall thermal sensation in non-uniform environments. The overall thermal sensation in non-uniform environments can be evaluated by the RST if, when determining the RST, the measuring site exposed to local cooling is involved and given a high weight.

Thermal deformity and thermolysis of magnetized and fractional Newtonian fluid with rheological investigation

Thermolysis and its deformities can occur at every developmental stage at all temperatures during the process of heating, pyrolysis mechanism, and thermodynamical decompositions. This manuscript investigates thermal-fluid flow of a magnetized Newtonian fluid under the influence of porosity via modern fractional differential approaches. The mathematical modeling of thermal-fluid flow of the magnetized Newtonian fluid is developed for temperature distribution and velocity profile under the Mittag–Leffler function as an imposed boundary condition. The governing equations of thermal-fluid flow of the magnetized Newtonian fluid are non-dimensional and fractionalized through modern non-integer differentiations. The mathematical model of thermal-fluid flow for the magnetized Newtonian fluid is tackled via integral transforms for generating exact analytical solutions. For the sake of comparative analysis of thermodynamical aspects, the Nusselt number from the thermal fractional model and skin friction from the momentum fractional model have been compared graphically via two types of modern non-integer differentiations and statistical observations. The results indicate and suggest the significant impacts in realistic hypothesis.

Regional and Seasonal Variability of the Oceanic Thermal Skin Effect

AbstractThe heat exchange between the ocean and atmosphere through turbulent and radiative processes is a fundamental component of the climate system. An accurate representation of the physical processes at the ocean thermal skin layer in numerical weather prediction and climate models is critical to the skill of the model forecasts and the fidelity of derived fields. Over many years we have deployed instruments on many ships to measure the sea‐surface skin temperature and variables that control surface exchanges. Here, the nighttime cool skin and daytime diurnal warming characteristics are investigated using our ship data in the Caribbean region. Overall comparisons with existing parameterizations and models show encouraging results: the biases of various cool skin schemes vary between −0.128 and 0.028 K; a new cool skin equation was derived. Several diurnal warming models are evaluated, with their accuracies being related to the wind speed, time, shortwave‐radiation, and air‐sea temperature difference.

Physiological Indices and Subjective Thermal Perception of Heat Stress-Exposed Workers in an Industrial Plant

This study aimed to investigate the thermal responses of acclimated workers exposed to heat stress in a real work environment. The physiological indices and subjective thermal perception of the 14 acclimated workers were measured in an industrial plant. The effects of wet bulb globe temperature (WBGT) on physiological indices and subjective thermal perception were studied. The differences in thermal responses between the acclimated workers and unacclimated college students exposed to heat stress were compared and analyzed. The relationship between the mean skin temperature and the thermal sensation was revealed. The results show that the mean skin temperature, oral temperature, and heart rate of the acclimated workers increase with WBGT, while the blood pressure decreases with WBGT. Compared with the unacclimated college students, the acclimated workers felt more comfortable and tolerant under the same heat stress. The thermal neutral mean skin temperature of the acclimated workers is 32.3 °C, which is approximately 1.0 °C lower than that of the unacclimated college students. The results of this study can help ensure the occupational safety and health of heat stress-exposed workers.

Efficacy and safety of a thermal fractional skin rejuvenation system (Tixel) for the treatment of facial and/or scalp actinic keratoses.

Actinic keratoses are common cutaneous lesions with a potential to progress to invasive squamous cell carcinoma. Therefore, treatment is crucial. The Tixel® is a noninvasive thermomechanical device designed to transfer heat to the upper dermis in a controlled manner according to a predetermined setting. This study aimed to evaluate the safety and efficacy of a thermomechanical fractional skin resurfacing technology for the treatment of facial and scalp actinic keratoses. A prospective, open-label, before-after study was conducted in a tertiary medical centre from May 2020 to April 2021. Patients presenting with facial/scalp actinic keratoses of mild-to-moderate thickness underwent 2 or 3 Tixel treatments (depending on clinical improvement), 3-4weeks apart. The reduction in lesion count and overall improvement in appearance were assessed by clinical examination and digital photography. Findings were compared between baseline and follow-up at 3months after the last treatment session. Patient satisfaction was evaluated by questionnaire, and adverse effects were documented. A total of 20 patients participated in the study. All completed 2-3 treatments and follow-up visits. Assessment of digital photographs was performed by 2 assessors blinded to the timepoint at which each photo was taken (before or after treatment). The average number of lesions at baseline was 9.8 (± 4.8) and the mean reduction in lesion count was 7.9 (± 4.4) (80.6%). Complete clearance was observed in 31.6% of patients. No adverse effects were noted during treatment and follow-up. Most patients reported being "very satisfied" or "satisfied" with the treatment results (85%) and experience (95%). Treating facial and scalp actinic keratoses with the Tixel device was found to be effective and safe.

Climate Chamber Experiment Study on the Association of Turning off Air Conditioning with Human Thermal Sensation and Skin Temperature

To date, few attempts have been made to associate air conditioning behavior with environmental conditions and the occupants’ thermal sensations and physiological states simultaneously. In this study, a series of experiments were conducted in a climate chamber environment, representative of a typical intermittent air conditioning process in residences. For 29 participants, local skin temperatures, thermal sensation and the participants’ intention of turning off air conditioning were recorded continually. Skin temperature and thermal sensation were found to keep decreasing over time, which in turn triggered turning off air conditioning. It is also noted that participants reported different thermal sensations when they intended to turn off air conditioning. However, there was no statistically significant difference in skin temperature of exposed body parts such as foot and calf. Additionally, given the ambient set temperature, the probability of turning off air conditioning exponentially increased with the increasing air conditioning duration. Accordingly, from a physiological perspective, the occupants’ behavior of turning off air conditioning was largely dependent on the local skin temperature of exposed body parts. From an environmental perspective, air conditioning duration demonstrated influences on the air conditioner switch-off. The lower the ambient temperature or the longer the exposure to air conditioning environment, the stronger the intention of the participants to turn off air conditioning.

Chitin Nanofibril-Nanolignin Complexes as Carriers of Functional Molecules for Skin Contact Applications.

Chitin nanofibrils (CN) and nanolignin (NL) were used to embed active molecules, such as vitamin E, sodium ascorbyl phosphate, lutein, nicotinamide and glycyrrhetinic acid (derived from licorice), in the design of antimicrobial, anti-inflammatory and antioxidant nanostructured chitin nanofibrils–nanolignin (CN-NL) complexes for skin contact products, thus forming CN-NL/M complexes, where M indicates the embedded functional molecule. Nano-silver was also embedded in CN-NL complexes or on chitin nanofibrils to exploit its well-known antimicrobial activity. A powdery product suitable for application was finally obtained by spray-drying the complexes co-formulated with poly(ethylene glycol). The structure and morphology of the complexes was studied using infrared spectroscopy and field emission scanning electron microscopy, while their thermal stability was investigated via thermo-gravimetry. The latter provided criteria for evaluating the suitability of the obtained complexes for subsequent demanding industrial processing, such as, for instance, incorporation into bio-based thermoplastic polymers through conventional melt extrusion. In vitro tests were carried out at different concentrations to assess skin compatibility. The obtained results provided a physical–chemical, morphological and cytocompatibility knowledge platform for the correct selection and further development of such nanomaterials, allowing them to be applied in different products. In particular, chitin nanofibrils and the CN-NL complex containing glycyrrhetinic acid can combine excellent thermal stability and skin compatibility to provide a nanostructured system potentially suitable for industrial applications.

How the nozzle density and height of mist spraying affect pedestrian outdoor thermal comfort: A field study

We explored the effects of mist spraying with different nozzle densities and heights on pedestrian thermal comfort during summer in Xi'an, China. Thermal perceptions of 106 college students in open spaces (sky view factors: 0.598–0.699) varying in nozzle density (4, 6 and 8 nozzles) and height (2.3, 2.7 and 3.1 m) in a 4.5 m2 area were investigated using meteorological variables measured at 1.1 m above the ground and longitudinal questionnaire surveys. Universal Thermal Climate Index and skin temperature were selected to evaluate thermal perceptions and physiology. We found that: 1) Effects of mist spraying on humidification (2.60–7.03%), reducing globe temperature (6.55–15.15 °C) and mean radiant temperature (9.77–31.52 °C) increased as the nozzle number increased from 4 to 8. The effect of humidification declined as the nozzle height increased from 2.3 to 3.1 m (7.03–2.60%). 2) Subjects' thermal sensation vote decreased as the nozzle number increased from 4 to 8, and increased with nozzle height from 2.3 to 3.1 m. 3) ST reduction measured at the forehead (0.45–1.24 °C) and upper arm (0.38–0.95 °C) increased as the nozzle number increased from 4 to 8. Mean ST reduction decreased (0.72–0.53 °C) as the nozzle height increased from 2.3 to 3.1 m with 8 nozzles. 4) The UTCI reduction resulting from adding a nozzle was equivalent to lowering nozzle height by 0.82 m. A model of the nozzle density and height was built to predict when respondents would perceive neutral UTCI in misted environments.

Gradual Sequestration of Water at Lunar Polar Conditions due to Temperature Cycles

Abstract Migration of water molecules into the porous lunar soil can lead to sequestration of adsorbed water or ice at depth. Here, this process is modeled at several potential landing sites in the south polar region of the Moon. Desorption times are parameterized based on the Brunauer–Emmett–Teller (BET) isotherm model. Water sequestration is significant at depths where subsurface temperatures remain below the cold-trapping threshold, a condition satisfied at one of three sites considered, west of Haworth Crater. Model calculations predict a hydrated layer below a desiccated layer. The thickness of the desiccated layer is on the scale of the thermal skin depth, which for dust is typically centimeters. The underlying layer, decimeters thick, can be hydrated over a timescale of a billion years, reaching abundances on the order of 1 wt%. This sequestration process potentially simultaneously explains excess hydrogen concentrations outside of cold traps and the observed presence of a desiccated layer above a hydrogenous layer.

Influence of Eearly Necrectomy in Pregnant Rats with Deep Thermal Skin Burns on Maternal Oxygen-Dependent Processes and Further Course of Pregnancy

Influence of Eearly Necrectomy in Pregnant Rats with Deep Thermal Skin Burns on Maternal Oxygen-Dependent Processes and Further Course of Pregnancy

НИЗКОИНТЕНСИВНОЕ ЛАЗЕРНОЕ ОБЛУЧЕНИЕ КРОВИ И ЕГО ЭФФЕКТИВНОСТЬ ДЛЯ КОРРЕКЦИИ НАРУШЕНИЙ СИСТЕМЫ ГОМЕОСТАЗА У БЕРЕМЕННЫХ КРЫС С ТЕРМИЧЕСКИМИ ОЖОГАМИ КОЖИ

Background. Treatment of burn injuries is one of the most acute and urgent problems of combustiology, despite all the achievements of modern medicine. With skin burns, multiple systemic changes occur that require special attention and new approaches. Low-intensity laser blood irradiation is a highly effective method of non-pharmacological corrective effect on the homeostasis system of burned patients, but remains unexplored in pregnant women with thermal skin burns. The aim of the research. To evaluate the effectiveness of low-intensity laser blood irradiation for the correction of disorders of the homeostasis system in pregnant rats with thermal skin burns. Material and methods. An experimental study was carried out on 81 female outbred white rats weighing 200-250 g, which were divided into three groups. The control group consisted of pregnant intact rats, the first experimental group - rats with thermal skin burns in the early period of pregnancy, the second experimental group - rats with thermal skin burns in the early period of pregnancy, which underwent low-intensity laser blood irradiation. The oxygen transport function of blood, acid-base status and basic biochemical parameters of blood were studied. Results. Thermal burns of the skin in rats in the early period of pregnancy are accompanied by a deterioration in the oxygen transport function of the blood (a decrease in PO2 and SO2 values, a decrease in the affinity of hemoglobin for oxygen) and the development of metabolic acidosis, as well as the presence of endogenous intoxication (an increase in the concentration of urea and creatinine, an increase in the level of liver enzymes). The use of low-intensity laser irradiation of blood makes it possible to improve homeostasis indices in a shorter time. Conclusions. Low-intensity laser irradiation of blood improves the main indicators of the oxygen transport function of the blood and reduces the level of endogenous intoxication during skin burns in rats in the early period of pregnancy.

Exploring the Impact of Green Walls on Occupant Thermal State in Immersive Virtual Environment

Green walls have been used in built environments as a natural element to bring various benefits, thus improving human health and well-being. However, in conventional virtual environments, the visual connection with a green wall is the only way that this natural element could benefit humans. Unfortunately, the impact of such visual connection on human thermal perception is still not well understood. Thus, we conducted an experimental study with 40 participants comparing the thermal state of two virtual sessions: biophilic (a room with a green wall) and non-biophilic (the same room without a green wall). Both sessions were conducted in a climate chamber under a slightly warm condition (28.89 °C and 50% relative humidity). Participants’ thermal state, skin temperature, and heart rate data were collected. According to the results, participants’ thermal comfort and hand skin temperature were significantly different between the two sessions, and their mean skin temperature was statistically increased over time. The study suggests that before the extent to which the impact of visual stimuli (e.g., green walls) on thermal perception is fully understood, researchers may need to control visual and thermal stimuli separately when using them in immersive virtual environments. Furthermore, the virtual exposure time should be an important consideration when designing experimental procedures.

Multi-objective 4E analysis for a building integrated photovoltaic thermal double skin Façade system

In this research paper, energy, exergy, economic and environmental analysis of a building integrated photovoltaic thermal system is investigated. To cover the aim of the research, the impact of a system as a retrofit solution for the existing office building has been evaluated in different scenarios through various key performance indicators including generated electricity, energy and exergy efficiency, greenhouse gas emission reduction and life cycle cost. The scenario development for the analysis is based on the variation between glass windows and photovoltaic module surface area on the outer façade. According to the results of the study, a scenario with the lowest photovoltaic module and highest glass windows surface area has been suggested due to the highest energy efficiency, lowest initial investment, lowest energy consumption and emission for manufacturing. Besides, a scenario with the highest photovoltaic module and zero glass windows surface area has been suggested because of the highest lifetime generated and avoided energy and emission reduction, lowest payback time and greenhouse gas rate as well as highest life cycle revenue. In conclusion, a scenario with the highest photovoltaic module surface area with a payback time of 1.58 years and a life cycle revenue of 55,157 (USD) has been suggested as a feasible retrofit measure as a result of the energy, exergy, economic and environmental analysis.

Thermal skin burn in a late gestation period in experimental animals: state of the system “mother-fetus”

Objective. To study the effect of thermal skin burns in experimental animals (rats) on the state of the system “mother-fetus” in a late gestation period.Materials and methods. An experimental study was carried out on 18 female outbred white rats weighing 300–350 g (per 9 rats in the control and experimental groups), which were exposed to third-degree thermal burns with an area of 12 cм2 in a late gestation period. The oxygen transport function and the main blood biochemical markers were studied. The effect of thermal injury on the course of pregnancy was studied.Results. The thermal skin burn in the rats in the late gestation period leads to the development of hypoxia, a decrease in the affinity of hemoglobin for oxygen and metabolic acidosis in the mother’s body. Changes in the blood biochemical markers indicate the presence of endogenous intoxication. In the experimental animal group, a decrease in fetal weight was observed, an increase in the post-implantation fetal death rate was noted.Conclusion. Impaired oxygen homeostasis and endogenous intoxication in skin burns in rats in late gestation periods lead to fetal malnutrition and a qualitative increase in the post-implantation fetal death rate.

Morphological changes in the white rats’ thyroid gland 14 days after simulated thermal trauma of the skin on the background of the administration of 0.9 % NaCl solution

According to the World Health Organization (WHO), there are about 11 million burns in the world each year, of which 180,000 are fatal. One of the systemic consequences of burn injuries is the so-called burn-associated hypermetabolism, the clinical picture of which includes immunological dysfunction, loss of bone mineral density, endocrine disorders, including thyroid dysfunction. The aim of the study was to establish histological and ultrastructural changes of the thyroid gland of experimental animals 14 days after the simulated thermal trauma of the skin on the background of using first 7 days 0.9 % NaCl solution. At the optical and ultrastructural levels of the study 14 days after thermal skin burn on the background of 0.9 % NaCl solution in the thyroid gland of experimental animals found: follicles – mostly large, overstretched (epithelium flat, with desquamation); cytoplasm of thyrocytes is poor in organelles, part of mitochondria with damaged cristae and enlightened matrix, available electron-dense lysosomes, apical surface smoothed; there is swelling of the capsule and trabeculae, leukocyte infiltration; components of the arterial and venous bed are dilated, there is a deformation of the lumen of blood vessels; hemocapillaries are dilated with numerous erythrocytes and perivascular edema. The detected changes cause a violation of the secretory cycle of thyrocytes, transendothelial metabolism and lead to an imbalance in the production and excretion of thyroid hormones.

Relationship between pressure and thermal pain threshold, pain intensity, catastrophizing, disability, and skin temperature over myofascial trigger point in individuals with neck pain

The objective of the study was to correlate the thermal pain threshold (heat and cold) on myofascial trigger points with measurements of pain and skin temperature in patients with chronic neck pain. This is a cross-sectional study. We included participants of both genders, aged between 18-45 years, with chronic neck pain (>90 days), and with active bilateral myofascial trigger point centrally located in the upper trapezius muscle. Neck Disability Index, Numerical Rating Scale, Pain-Related Catastrophizing Thoughts Scale, algometry, infrared thermography, and quantitative sensory testing were used for the evaluation. A significant, weak, and negative association was observed between pain intensity and heat pain threshold on the myofascial trigger point to the right (rho -0.381, p=0.022) and to the left (rho -0.334, p=0.049), and a significant, weak, and positive association was observed between pain intensity and cold pain threshold on the myofascial trigger point to the right (rho 0.471, p=0.004) and to the left (rho 0.339, p=0.043). Thermal pain threshold (heat and cold) on myofascial trigger points is associated with pain intensity in individuals with chronic neck pain.

Seasonal and Diurnal Variability of the Thermal Skin Layer Characteristics Based on a Comparison of Satellite Measurements by SEVIRI and Data from Temperature-Profiling Drifters

Seasonal and Diurnal Variability of the Thermal Skin Layer Characteristics Based on a Comparison of Satellite Measurements by SEVIRI and Data from Temperature-Profiling Drifters

Application of Causal Inference to the Analysis of Occupant Thermal State and Energy Behavioral Intentions in Immersive Virtual Environments

Identification and quantitative understanding of factors that influence occupant energy behavior and thermal state during the design phase are critical in supporting effective energy-efficient design. To achieve this, immersive virtual environments (IVEs) have recently shown potential as a tool to simulate occupant energy behaviors and collect context-dependent behavior data for buildings under design. On the other hand, prior models of occupant energy behaviors and thermal states used correlation-based approaches, which failed to capture the underlying causal interactions between the influencing factors and hence were unable to uncover the true causing factors. Therefore, in this study, the authors investigate the applicability of causal inference for identifying the causing factors of occupant/participant energy behavioral intentions and their thermal states in IVE condition and compare those results with the baseline in-situ condition. The energy behavioral intentions here are a proximal antecedent of actual energy behaviors. A set of experiments involving 72 human subjects were performed through the use of a head-mounted device (HMD) in a climate chamber. The subjects were exposed to three different step temperatures (cool, neutral, warm) under an IVE and a baseline in-situ condition. Participants' individual factors, behavioral factors, skin temperatures, virtual experience factors, thermal states (sensation, acceptability, comfort), and energy behavioral intentions were collected during the experiments. Structural causal models were learnt from data using the elicitation method in conjunction with the PC-Stable algorithm. The findings show that the causal inference framework is a potentially effective method for identifying causing factors of thermal states and energy behavioral intentions as well as quantifying their causal effects. In addition, the study shows that in IVE experiments, the participants' virtual experience factors such as their immersion, presence, and cybersickness were not the causing factors of thermal states and energy behavioral intentions. Furthermore, the study suggests that participants' behavioral factors such as their attitudes toward energy conservation and perceived behavioral control to conserve energy were the causing factors of their energy behavioral intentions. Also, the indoor temperature was a causing factor of general thermal sensation and overall skin temperature. The paper also discusses other findings, including discrepancies, limitations of the study, and recommendations for future studies.