A novel cooling method using carbon dioxide-rich water after passive heating.

BackgroundBecause carbon dioxide (CO2)-enriched water causes cutaneous vasodilation, immersion in CO2-enriched water facilitates heat transfer from the body to the water or from the water to the body. Consequently, immersion in CO2-enriched water raises or reduces body temperature faster than immersion in fresh water. However, it takes time to dissolve CO2 in tap water and because the dissolved CO2 concentration decreases over time, the actual CO2 concentration is likely lower than the stated target concentration. However, it is unclear whether water containing a lower CO2 concentration would also cool the body faster than fresh water after body temperature had been increased.MethodsTen healthy males (mean age = 20 ± 1 years) participated in the study. Participants were first immersed for 15 min in a tap water bath at 40 °C to raise body temperature. They then moved to a tap water or CO2-enriched water bath at 30 °C to reduce body temperature. The CO2 concentration was set at 500 ppm. The present study measured cooling time and cooling rate (slope of the regression line relating auditory canal temperature (Tac) to cooling time) to assess the cooling effect of CO2-enriched water immersion.ResultsImmersion in 40 °C tap water caused Tac to rise 0.64 ± 0.25 °C in the tap water session and 0.62 ± 0.27 °C in the CO2-enriched water session (P > 0.05). During the 30 °C water immersion, Tac declined to the baseline within 13 ± 6 min in tap water and 10 ± 6 min in CO2-enriched water (P > 0.05). Cooling rates were 0.08 ± 0.06 °C/min in tap water and 0.08 ± 0.04 °C/min in CO2-enriched water (P > 0.05).ConclusionsCO2-enriched water containing 500 ppm CO2 did not cool faster than tap water immersion. This suggests that when the water temperature is 30 °C, a CO2 concentration of 500 ppm is insufficient to obtain the advantageous cooling effect during water immersion after body temperature has been increased.

Remarkably, bathing in hot springs containing high concentrations of carbon dioxide (CO(2)) influences cardiovascular function more than bathing in fresh water. The CO(2)-enriched water in hot springs generally contains many salts, whose interactions remain unknown. We separately evaluated the actions of individual factors in CO(2)-enriched water and confirmed that CO(2) and NaCl have combined effects on blood pressure fluctuations in anesthetized rats. Animals equipped with sensor probes to monitor body temperature, skin blood flow and arterial blood pressure were immersed in bathwater (35 degrees C) containing CO(2) with NaCl, KCl or sucrose. The effects of these factors on cardiovascular function were evaluated using power-spectral analysis of fluctuations in blood pressure and heart rate. Compared with immersion in tap water, heart rate and skin vascular resistance were reduced during immersion in CO(2)-enriched water irrespective of the presence of other components. In terms of the very low frequency range (0.02-0.195 Hz), the power of blood pressure fluctuation during immersion was significantly reduced when the CO(2)-enriched water contained more than 1.5% NaCl but was not influenced by other components of similar osmotic pressure and the same specific gravity. The results indicated that the coexistence of CO(2) and sodium ions in bathwater reduce blood pressure fluctuations, and suggested that this combination effect of CO(2) and salt contributes to the sedative effect on human cardiovascular functions while bathing in CO(2)-hot springs.

Accelerated cine-photographs show that the unfertilized trout egg exhibits rhythmical movements within its chorion after immersion in tap water. The movement can be described as a periodic axial perturbation or ‘precession’, similar to that which takes place in a slowing-down top. The egg does not, however, spin at the same time. The frequency of the motion is about 3·4 min. at 16·8° C. There is a strict correlation between the frequency of the egg precession and the frequency of the impedance changes that are observed when the egg is placed in a conductivity cell in an alternating current bridge. The impedance changes exhibit a characteristic ‘impedance pattern’, the frequency of which is identical with that of the precession. The oscillations are neither initiated nor affected by the measuring current. The question as to whether the electrical changes are entirely caused by the dielectric heterogeneity and precession of the egg, or whether they are partly due to changes in the vitelline membrane, associated with the egg movements, is discussed. The former is the simpler hypothesis, and there is some evidence in support of this interpretation from impedance measurements made with the electrodes in different planes relative to the egg. It was difficult to reach a firm decision on this point because the electrical method of recording the changes is more sensitive and accurate than existing optical methods. Examination of the fine structure of the impedance cycle, by means of the ellipse technique and enlarged time-impedance loci at particular frequencies, shows that there is a very small resistance change associated with the impedance oscillations, which is not in phase with the capacitance change. The possibility of these resistance changes being due to variations in the position of the egg relative to the measuring electrodes; combined with small deviations from Maxwell’s formula, or to resistive heterogeneity in the vitelline membrane, or to changes in the resistance of the vitelline membrane, is discussed. The variation of frequency with temperature has been investigated. In one typical run, the temperature characteristic was 15,200 which corresponds to a Q10 of 2·47. The average value of the temperature characteristic for the whole season was 16,200. There are no obvious ‘breaks’ in the curve relating log velocity to the reciprocal of the absolute temperature; the curve obeys Arrhenius’s equation except at temperatures above 18° C., when irreversible changes tend to set in. There is no very convincing reason for associating this temperature characteristic with developmental processes, particularly as measurements are made on unfertilized eggs. On the other hand, the possibility of all unfertilized eggs undergoing abortive partheno-genetic activation on immersion in tap or stream water is discussed. Sodium cyanide (M/300, M/500, M/100 in tap water, pH adjusted) reversibly reduces the frequency and amplitude of the impedance changes, which suggests that cytochrome is concerned in the metabolic system responsible for the egg movements. The frequency is more sensitive to cyanide than the amplitude. There are indications that this compound has some effect on the electrical properties of the vitelline membrane, but this has not been systematically examined. Sodium azide, which has no effect at pH 7·4, cannot be used at pH 6·5 because this concentration of H+ in the external medium has a marked, though not permanent, effect on the egg movements and impedance changes. Neither phlorizin (M/100, M/200, M/500 in tap water, pH not adjusted), nor sodium fluoride (M/25, pH not adjusted) have any effect on the egg movements or the impedance cycle. This suggests that the energy for these changes is not glycolytic in origin; but there is a possibility that the molecules of these inhibitors do not penetrate the vitelline membrane. The action of the inhibitors does not as yet permit any comparison to be made with ciliary or amoeboid movement, or with muscular contraction, as the experiments do not enable a distinction to be made between the utilization of oxygen in the breakdown phase or the resynthesis phase of the metabolic cycle. The following substances have no effect on egg movements or impedance changes: Laboratory-distilled water. There is a possibility that distilled water affects the properties of the vitelline membrane, in the sense that some exosmosis of electrolytes occurs when the egg is in the medium. This has not been systematically examined as it has no direct bearing on the egg oscillations.M/25-CaCl2 in tap water.0·001 M-chloretone in tap water.There is no appreciable periodic change in egg volume.

BackgroundCold therapy has the disadvantage of inducing vasoconstriction in arterial and venous capillaries. The effects of carbon dioxide (CO2) hot water depend mainly on not only cutaneous vasodilation but also muscle vasodilation. We examined the effects of artificial CO2 cold water immersion (CCWI) on skin oxygenation and muscle oxygenation and the immersed skin temperature.Subjects and MethodsFifteen healthy young males participated. CO2-rich water containing CO2 >1,150 ppm was prepared using a micro-bubble device. Each subject’s single leg was immersed up to the knee in the CO2-rich water (20 °C) for 15 min, followed by a 20-min recovery period. As a control study, a leg of the subject was immersed in cold tap-water at 20 °C (CWI). The skin temperature at the lower leg under water immersion (Tsk-WI) and the subject’s thermal sensation at the immersed and non-immersed lower legs were measured throughout the experiment. We simultaneously measured the relative changes of local muscle oxygenation/deoxygenation compared to the basal values (Δoxy[Hb+Mb], Δdeoxy[Hb+Mb], and Δtotal[Hb+Mb]) at rest, which reflected the blood flow in the muscle, and we measured the tissue O2 saturation (StO2) by near-infrared spectroscopy on two regions of the tibialis anterior (TA) and gastrocnemius (GAS) muscles.ResultsCompared to the CWI results, the Δoxy[Hb+Mb] and Δtotal[Hb+Mb] in the TA muscle at CCWI were increased and continued at a steady state during the recovery period. In GAS muscle, the Δtotal[Hb+Mb] and Δdeoxy[Hb+Mb] were increased during CCWI compared to CWI. Notably, StO2values in both TA and GAS muscles were significantly increased during CCWI compared to CWI. In addition, compared to the CWI, a significant decrease in Tsk at the immersed leg after the CCWI was maintained until the end of the 20-min recovery, and the significant reduction continued.DiscussionThe combination of CO2 and cold water can induce both more increased blood inflow into muscles and volume-related (total heme concentration) changes in deoxy[Hb+Mb] during the recovery period. The Tsk-WI stayed lower with the CCWI compared to the CWI, as it is associated with vasodilation by CO2.

Geochemical Study on CO2-rich Waters of Daepyeong Area, Korea: Monitoring Implication for CO2 Geological Storage

The soft tick, Argas persicus, is the most important ectoparasite in chicken and other domestic fowl, well as in humans. The main aim of this study was to evaluate the survival rate of A. persicus under three different environmental conditions, including immersion in tap water, immersion in oxygenated water and after being placed and washed along clothes in an ordinary washing machine. Adult and larval ticks were separately immersed in tap and oxygenated water for six different time periods: 1, 6, 24, 48, 72 hours and 1 week. Both adults and larvae survived up to 72 hours immersion in tap water. All the ticks immersed in tap water died during the first week; while 53.3% of adult ticks survived one week immersion in oxygenated water. To evaluate the survival rate of ticks in the washing machine, only adults were used and the ticks were placed in a small hub filter before being placed in a Samsung washing machine at three different temperatures (30, 40 and 60°C). At the end of each cycle, we counted the surviving ticks. All ticks survived 30 and 40 °C, while only 13.3% survived at 60 °C. In conclusion, adult and larval stages of A. persicus survived under water for couple of days while washing in regular washing machine did not kill adult ticks under temperatures of 30 and 40 °C. So in order to kill the ticks in clothes temperatures more than 60°C should be used.

Among the different forms of hydrotherapy, carbon dioxide (CO2) water immersion improves peripheral vasodilation and blood flow compared with tap water immersion; however, the heat stress placed on the body through CO2 water immersion and the appropriate immersion protocols are uncertain. Therefore, this study aimed to compare the thermoregulatory responses during CO2 and tap water immersions. The participants were 10 male college baseball players. After daily training was completed, intervention was performed for 15 min under three conditions: (1) CO2 water immersion (CO2; 40°C, 1000 ppm), (2) tap water immersion (TAP; 40°C), and (3) seated at rest at room temperature (control [CON]; at 25°C and relative humidity of 60%). Core body temperature (Tcore), skin temperature (Tsk), heart rate (HR), skin blood flow, local sweat rate (LSR), and blood pressure were measured. The Tcore, Tsk, thermal sensation (TS), and HR were significantly higher in the CO2 and TAP trials than in the CON trial. Compared to tap water immersion, CO2 water immersion resulted in higher Tcore and LSR values, with moderate to large effect sizes (Tcore: d = 0.52, LSR: d = 0.80). However, thermal discomfort did not increase, suggesting that CO2 water immersion may increase heat stress without causing any negative effects.

This paper analyzes the autogenous self-healing capacity of early-age Ultra-High-Performance Fiber-Reinforced concretes (UHPFRCs) by measuring the crack closure and the possible mechanical recovery on healed specimens. The main parameters considered in this research were the healing exposure conditions (humidity chamber, immersion in tap water, immersion in seawater and heat curing) and the precracking levels (microcracks and macrocracks). For the microcrack level, four-point bending tests were performed on prismatic specimens (100 × 100 × 500 mm3) obtaining a multiple cracking pattern characterized by crack widths ranged from 10 to 20 µm. Whereas for the macrocrack level (behavior after crack localization), splitting tests were carried out on notched cubic specimens (100 × 100 × 100 mm3) obtaining crack widths of up to 0.4 mm. For both precracking levels, specimens were precracked at two days and were cured for one month in the mentioned exposure conditions. Healing products were analyzed on the specimen surface and also inside the cracks; to this purpose, their microstructure was analyzed by means of SEM and EDS analyses. The results have shown that the highest crack closure values were obtained for the heat-cured specimens and for the specimens immersed in water (tap water and seawater) whereas the less efficient condition was the humidity chamber.

Springs and hot spas have been used worldwide since ancient times as sources of potable, medicinal and bathing water, as well as for industrial purposes. They also sustain spring-dependent ecosystems and provide water flow to downstream ecosystems. We investigated the major element hydrogeochemistry of traditional springs, CO2-rich waters, and hot spas in South Korea and their relationships with features of bedrock geology and structural settings at the national scale to classify water types and identify the major factors controlling the occurrence of each water type. Three criteria—mineral content, CO2(aq), and water temperature—defined six major water types. Alkaline mineral water in carbonate rocks and sedimentary rocks result from readily weatherable lithology. The majority of mineralized waters are CO2-rich or thermal waters with a wide range of mineral contents. Their occurrence was found to be mainly concentrated near faults and boundaries between Early to Middle Jurassic granitic rocks and other rocks of much older ages, and this pattern was quantitatively identified through proximity analysis. This finding indicates that younger granitic rocks provide sources of heat and deep-seated CO2, and faults link these deep sources to groundwater flow. Hydrolysis of primary silicate minerals, including feldspar and biotite, is likely to supply major and minor solutes including Mg2+, F-, and Fe to CO2-rich and thermal waters. F- concentration appears to be regulated by the saturation states of calcite and fluorite, and Mg2+ concentration in alkaline thermal water is driven by the formation of Mg-bearing secondary silicates. We demonstrated that natural mineral water in tectonically stable regions has diverse thermal and hydrogeochemical properties that are mainly controlled by their lithological and structural settings at the regional scale. These results may help elucidate the generation processes of natural mineral waters with high cultural and ecological values, leading to their sustainable use and protection.

Background: Acute mirabegron (MIRA) ingestion, a pharmaceutical that activates β3-adrenergic receptors on brown adipose tissue (BAT), enhances energy expenditure during thermoneutral and cool air exposure (i.e., 20°C). Cold-water immersion (CWI) accelerates heat loss, thus challenging thermoregulation during immersion. It is not known whether the acute pharmacological activation of BAT can aid thermoregulation during a progressive CWI challenge. We tested the hypothesis that acute MIRA ingestion would increase markers of BAT activation, mitigate the reduction in body temperature, and extend CWI duration during a progressive CWI challenge vs. placebo (PLA). Methods: 12 healthy adults (age: 25±6 y; BMI: 26±5 kg/m 2 , body fat: 27±5%, 6 women) completed two, double-blind, randomized study visits: ingestion of 100 mg of MIRA or PLA. 30 min after ingestion, participants rested in an empty water immersion tank. Following baseline measures, 35°C water rapidly filled the tank up to the sternum. The temperature of the water was progressively cooled by 2.5°C every 15 min until reaching 10°C, where it was held constant for up to 240 min of total immersion time. Participants were asked to remain in the water for as long as possible or complete 240 min of immersion. O 2 consumption (VO 2 ; ml/kg/min), CO 2 production (VCO 2 ; ml/kg/min), and respiratory exchange ratio (RER) were measured using indirect calorimetry. BAT activity was estimated via supraclavicular skin temperature (T sc ; infrared thermography) and expressed relative to shoulder skin temperature. Mean skin temperature (T sk ; 12 sites), and rectal temperature (T c ) were measured and used to calculate mean body temperature (T b ). Shivering was assessed via mechanomyography (MMG; 3 tri-axial accelerometers) and the bedside shivering scale (BSS; 0 = no shivering, 3=severe shivering). Perceptual measures of thermal discomfort (1=comfortable, 4=very uncomfortable) and sensation (1=cold, 7=hot) were also measured. Data were captured at 15 min intervals up until the last common timepoint for all CWIs (i.e., 60 min). Values are reported as mean ± SD. Results: Total CWI duration was greater following MIRA ingestion vs PLA (127.1±55.0 vs 142.2±44.3 min; p =0.050). VO 2 (PLA: 7.2±3.1 vs MIRA: 7.6±3.3 ml/kg/min; condition effect p =0.579), VCO 2 (PLA: 6.2±2.8 vs MIRA: 6.5±2.9 ml/kg/min; condition effect p =0.559), and RER (PLA: 0.85±0.07 vs MIRA: 0.86±0.07; condition effect p =0.825) did not differ between conditions. MIRA elicited greaterT sc (PLA: 36.0 ± 0.1 vs MIRA: 36.3±0.4°C; condition effect p =0.014) and relative T sc (PLA: 1.5± 0.4 vs MIRA: 1.9±0.4°C; condition effect p =0.003) vs PLA. MIRA caused higher T sk (PLA: 29.9± 2.3 vs MIRA: 31.2±1.6°C; condition effect p =0.013) and T b (PLA: 34.5±0.8 vs MIRA: 34.9±0.5°C; condition effect p =0.015) vs PLA, but T c did not differ between conditions (PLA: 37.0±0.2 vs MIRA: 37.0±0.2°C; condition effect p =0.812). MMG (PLA: 0.7±0.1 vs MIRA: 0.7±0.1 cm 2 ; condition effect p =0.762), BSS (PLA: 0.1±0.3 vs MIRA: 0.1±03; condition effect p =0.777), thermal discomfort (PLA: 1.6±0.7 vs MIRA: 1.5±0.6; condition effect p =0.530), and thermal sensation (PLA: 3.5±1.1 vs MIRA: 3.4±1.1; condition effect p =0.363) did not differ between conditions. Conclusion: Our data indicate that acute ingestion of MIRA extended the duration of immersion during a progressive CWI challenge and mitigated reductions in body temperature. Further, MIRA ingestion augmented markers of BAT activity, suggesting that the pharmacological stimulation of BAT might improve resiliency during CWI. Funded by: Office of Naval Research N00014-21-1-2276 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Bond-slip behaviour between GFRP/steel bars and seawater concrete after exposure to environmental conditions

Tokishakuyakusan ameliorates lowered body temperature after immersion in cold water through the early recovery of blood flow in rats

Exercise capacity and performance are impaired in hot and humid environments, principally due to an increased body temperature and cardiovascular strain. Strategies that alleviate heat strain and improve exercise capability are therefore meaningful from a safety and performance perspective. These strategies are often assessed using core body temperature as a primary outcome, usually derived from inside the rectum, but increasingly from the intestinal tract using gastrointestinal telemetry pill systems. The reliability of intestinal temperature, however, was unclear. Therefore, the purpose of study 1 was to investigate the inter-day reliability of intestinal temperature during an exercise-heat challenge. Gastrointestinal temperature demonstrated good reliability but researchers and practitioners should be aware of potential heteroscedasticity as the magnitude of error increases with temperature. This information is useful when examining the effectiveness of strategies to alleviate heat strain and improve performance. Indeed, there are many interventions designed for this purpose, however, few are practical enough to be used during continuous exercise in hot environments. The objective of study 2 was to systematically identify and meta-analyse the effect of practical cooling strategies applied during exercise in hot environments. Cooling during fixed-intensity exercise before a self-paced performance trial improves endurance performance in the heat. These improvements are most likely mediated by an improved rating of perceived exertion and heat strain but not by attenuating an increase in body temperature. A potentially effective site for limiting increases in body temperature during exercise is the hands. Therefore, the purpose of study 3 was to quantify the physiological and perceptual responses to hand immersion in water during recumbent cycling in a hot environment. Hand immersion in cold water attenuated an increase in body temperature compared to a thermoneutral control and elicited beneficial effects on heart rate, skin temperature and skin blood flow. The aim of study 4 was to extend these findings to investigate the effects of prototype cooling gloves worn during exercise in a hot environment. The cooling gloves decreased indices of intestinal and skin temperature as well as heart rate. Beneficial effects were also observed for rating of perceived exertion, thermal comfort and thermal sensation. The findings from these studies have practical implications for assessments of interventions using gastrointestinal temperature, the choice of practical cooling strategy used during exercise in the heat and the application of hand cooling strategies. Future research should aim to improve the ergonomics of the cooling gloves designed in study 4 and investigate their impact on exercise capability in hot environments.

The impact of incorporating synthesized zeolite on Portland cement with different ratios was analyzed to enhance the healing effeciency of pre-cracked hardened matrix. The pre-cracked hardened specimens was subjected to treatment through immersion in tap water or a saturated lime solution, with the objective of enhancing the effectiveness of the healing process. These matrices represent the most frequently used environments suitable for crack healing. Given that water is a crucial component for cement hydration, saturated lime can alternatively be applied on cracks via spraying to facilitate the ability of heaing thr cracks. The outcomes demonstrated the effectiveness of repairing the pre-cracked structure in both conditions, while the fully saturated lime possesses a higher potential in mending the cracks, as evident from visual observation and petrographicanalysis. Additionally, Fourier Transform Infrared Spectroscopy revealed the incorporation of synthesized zeolite into the structure resulted in an enhancement of the intensity of the formed binder, which interm positively influenced its healing ability. The highest compressive strength was observed in specimens with 4% zeolite addition immersed in tap water, reaching 89 MPa. Furthermore, the compressive strength increased to 116 and 157 MPa with 4% and 6% zeolite addition, respectively, in the fully saturated lime environment.

About the Zingiber zerumbet little is known about its cut flower postharvest and market, despite its high ornamental potential. The inflorescences, which resemble a compact cone, emerge from the base of the plants and start with green color changing to red with the age. This study objective was to characterize floral stem of ornamental ginger in two cultivate conditions and to evaluate the longevity of those submitted to post-harvest treatments. Flower stems were harvest from clumps cultivated under full sun and partial shade area, and were submitted to the postharvest treatments: complete flower immersion in tap water (CFI) or only the base stem immersion (BSI). The flower stems harvested from clumps at partial shade presented higher fresh weight, length and diameter of the inflorescences compared to flower stems harvested from clumps at full sun area. The flower stem bracts cultivated in full sun area changed the color from green to red 10.69 and 11.94 days after BSI and CFI postharvest treatments, and the vase life were 22.94 and 28.19 days, respectively. Flower stem harvest in partial shade area change the color only after 18.94 and 18.43 days and the vase life durability was 27.56 and 31.81, respectively. The complete immersion of the flower stem increase the vase life durability in 5.25 and 4.25 days compared to flowers kept with the stem base immersed only, in flower stems harvested from clumps cultivated in full sun area and partial shade area, respectively. Flower stems harvested from clumps cultivated in partial shade area and completely immerse in tap water during 3 hours increase the vase life durability in 8.87 days compared to flowers harvested from clumps cultivated in full sun area and base immersed only.