Impact of core electron temperature on current profile broadening with radiofrequency wave heating and current drive in EAST

In recent EAST experiments,current profile broadening characterized by reduced internal inductance has been achieved by utilizing radio-frequency current drives(RFCD).In contrast to previous density scan experiments,which showed an outward shift of the current density profile of lower hybrid current drive(LHCD)in higher plasma density,the core electron temperature(T_(e)(0))is found to affect the LHCD current profile as well.According to equilibrium reconstruction,a significant increase in on-axis safety factor(q0)from 2.05 to 3.41 is observed by careful arrangement of RFCD.Simulations using ray-tracing code GENRAY and Fokker–Planck code CQL3D have been performed to thoroughly analyze the LHCD current profile,revealing the sensitivity of the LHCD current profile to T_(e)(0).The LHCD current density tends to accumulate in the plasma core with higher current drive efficiency benefiting from higher T_(e)(0).With a lower T_(e)(0),the LHCD current profile broadens due to off-axis deposition of power density.The sensitivity of the power deposition and current profile of LHCD to T_(e)(0)provides a promising way to effectively optimize current profile via control of the core electron temperature.

Research progress in core body temperature measurement during target temperature management

Core body temperature(CBT)is increasingly attracting attention as crucial data during target temperature management(TTM).Accurate and continuous measurement of human CBT can effectively identify and monitor central high fever,and provide a basis for the effective implementation during TTM,which is therefore of great significance for human health care and disease monitoring.The reliable core measurement sites are nasopharynx,esophagus,bladder,rectum,pulmonary artery,etc.,but the measurement methods in these sites are all invasive.At present,the medical field is more inclined to noninvasive data collection methods through monitoring an appropriate site(such as forehead,mouth,or axilla)depending on clinical circumstances,so as to ensure the comfort and security of patients to the greatest extent.This review will provide reference choosing more safe and accurate temperature measurement methods for patients during TTM by reviewing the sites and accuracy of invasive and noninvasive CBT measurements.

Sufficiently Elevated Core Body Temperature May Be Necessary to Maintain Cerebral Blood Flow Response throughout the Morning

In comparison to a carbohydrate-rich breakfast, a nutritionally balanced breakfast reportedly leads to a higher core body temperature because of diet-induced thermogenesis (DIT) and also results in higher task performance. This study aimed to examine the relationships among the core body temperature, blood glucose level, cerebral blood flow, and cognitive performance when the core body temperature is raised to a similar extent as in DIT in the morning. This crossover study included 18 male participants who performed four sets of cognitive tests in the morning with four different foot baths and glucose intake conditions. In elevated body temperature (EBT) conditions, the core body temperature was increased by a foot bath at 42˚C or 39˚C, while in low body temperature (LBT) conditions, it was maintained at 35˚C by a foot bath;the participants received no glucose or two intakes of 20-g glucose for each thermal condition. In addition to the core body temperature measurement, the cerebral blood flow in the dorsolateral prefrontal cortex (DLPFC) was measured using near-infrared spectroscopy. Three blood collections were performed to measure the changes in blood glucose levels. The results revealed that in the EBT conditions, the core body temperature remained 0.3˚C - 0.5˚C higher than that at wake-up time, while the glucose intake conditions increased blood glucose levels which remained higher than those during fasting. No significant between-treatment difference was observed in the results of cognitive tests. However, the blood flow in the DLPFC increased during the second test period in the EBT/glucose and LBT/glucose conditions, whereas during the fourth test period, it increased solely in the EBT/glucose condition. Thus, in addition to the blood glucose level, an elevated core body temperature within the physiological range may be needed for long-term maintenance of the cerebral blood flow response.

Glutamine supplementation attenuates intestinal apoptosis by inducing heat shock protein 70 in heatstroke rats

BACKGROUND:Heatstroke is the most hazardous heat-related illness and has a high fatality rate.We investigated whether glutamine supplementation could have a protective effect on heatstroke rats.METHODS:Twenty-five 12-week-old male Wistar rats(weight 305±16 g)were randomly divided into a control group(n=5),heatstroke(HS)group(n=10),and heatstroke+glutamine(HSG)group(n=10).Seven days before heat exposure,glutamine(0.4 g/[kg·d])was administered to the rats in the HSG group by gavage every day.Three hours after heat exposure,serum samples were collected to detect white blood cells,coagulation indicators,blood biochemical indicators,and inflammatory cytokines in the rats.The small intestine tissue was stained to analyze pathological structural changes and apoptosis.Finally,immunohistochemistry and Western blotting were used to analyze the expression levels of heat shock protein 70(HSP70).Multiple comparisons were analyzed by using one-way analysis of variance,and the Bonferroni test was conducted for the post hoc comparisons.RESULTS:After heat exposure,the core temperature of the HS group(40.65±0.31°C)was higher than the criterion of heatstroke,whereas the core temperature of the HSG group(39.45±0.14°C)was lower than the criterion.Glutamine supplementation restored the increased white blood cells,coagulation indicators,blood biochemical indicators,and inflammatory cytokines that were induced by heatstroke to normal levels.The intestinal mucosa was injured,and the structure of tight junctions was damaged in the HS group;however,the structure of intestinal mucosal epithelial cells was stable in the HSG group.Glutamine supplementation alleviated intestinal apoptosis and up-regulated HSP70 expression.CONCLUSION:Glutamine supplementation may alleviate intestinal apoptosis by inducing the expression of HSP70 and have a protective effect on heatstroke rats.

Exertional heat illness risk factors and physiological responses of youth football players

Objective:To determine which intrinsic and extrinsic exertional heat illness(EHI)risk factors exist in youth American football players and observe perceptual and physiological responses of players during events(games and practices).Methods:Cross-sectional cohort study observing 63 youth football players,varying in position.Independent variables were league(weightrestricted(WR,n=27)and age-restricted(AR,n=36))and event type.Dependent variables were anthropometrics,work-to-rest ratio,and wet bulb globe temperature.Descriptive variables included preparticipation examination and uniform configuration.A subset of 16 players participated in physiological variables(heart rate and gastrointestinal temperature).Data collection occurred on 7 AR and 8 WR nonconsecutive practices and the first 3 games of the season.Results:Mean values for anthropometric variables were higher(p<0.05)in the AR league than the WR league.Work time(χ^2(1,111)=4.232;p=0.039)and rest time(χ^2(1,111)=43.41;p<0.001)were significantly greater for games,but ratios were significantly higher for practices(χ^2(1,111)=40.62;p<0.001).The majority of events(77%)observed were in black and red flag wet bulb globe temperature risk categories.A total of 57%of the players had a preparticipation examination,and up to 82%of events observed were in full uniforms.Individual gastrointestinal temperature and heart rate responses ranged widely and no players reached critical thresholds.Conclusion:Extrinsic(disproportionate work ratios,environmental conditions)and intrinsic(higher body mass index)EHI risk factors exist in youth football.Certain risk factors may be influenced by event and league type.National youth football organizations need to create thorough guidelines that address EHI risk factors for local leagues to adopt.

Inadvertent Postoperative Hypothermia at Post-Anesthesia Care Unit: Incidence, Predictors and Outcome

Background: Inadvertent postoperative hypothermia (IPH) is known to be associated with various adverse effects. The aim of this study was to evaluate the incidence, predictors and outcome of core inadvertent hypothermia on admission in the post-anesthesia care unit. Methods: Observational, prospective study in a Post-Anesthesia Care Unit. The study population consisted of adult patients after non-cardiac and non-neurologic surgery. Patients’ demographics, intraoperative and postoperative data were collected. Descriptive analysis of variables was used to summarize data and the Mann-Whitney U test, Fisher’s exact test or Chi-square test was used. Univariate and multivariate analyses were done with logistic binary regression with calculation of an Odds Ratio (OR) and its 95% Confidence Interval. Results: The incidence of IPH on admission was 32%. In univariate analysis: age, body mass index (BMI), high risk surgery, revised cardiac risk index (RCRI), type of anesthesia, use of forced-air warming, amount of intravenous crystalloids administrated, duration of anesthesia, duration of surgery and admission visual analogue scale (VAS) for pain > 3 were considered predictors of hypothermia. In multiple logistic regression analysis, age (OR 1.7, P = 0.045, for age > 65 years), RCRI (OR 3.18, P = 0.041, for RCRI > 2), duration of anesthesia (OR 1.52, P < 0.001) and admission VAS for pain (OR 2.05, P = 0.007) were considered independent predictors of IPH. Patients with IPH at PACU admission stay longer in the PACU. Conclusions: IPH was associated with a longer stay in the PACU. Age, comorbidities duration of anesthesia and pain at PACU admission were considered independent predictors for IPH.

The Impact of Fresh Gas Flow Sevoflurane Anesthesia on Perioperative Hypothermia in Adult Patients Undergoing Elective Open or Laparoscopic Digestive Surgery: A Prospective Randomized Controlled Trial

Background: Because body temperature is such an important indicator and a basic requirement for all kinds of life, even tiny variances might induce undesired changes. This study looked at the influence of FGFs sevoflurane anesthesia on heat preservation in patients undergoing open or laparoscopic digestive surgery. Materials and Methods: Two hundred and forty adult patients (18 - 75 years) with an ASA of I-II were scheduled for open and laparoscopic digestive surgery: open surgery (Group O, n = 120 patients) and laparoscopic surgery (Group L, n = 120 patients). Each group was separated randomly into four subgroups (n = 30 patients) based on FGFs (0.7, 1, 1.5, or 2 L/min). Each patient’s HR, MBP, SpO2, FiO2, fluid infusion amount, urine volume, pre/post-Hb, surgery time, and nasopharyngeal temperatures were investigated and recorded every 15 min from 0 to 120 min. Results: Between groupings, there were no significant changes in demographic features. In 240 patients, the results of various FGFs (0.7, 1, 1.5, and 2 L/min), no statistically significant differences were found in core body temperature over time within each subgroup, with no statistically significant differences between the two (open and laparoscopic) (P > 0.05). Conclusions: The study concluded that FGFs (0.7, 1, 1.5, and 2 L/min) could be utilized safely in adult patients undergoing open or laparoscopic digestive surgery. FGFs (0.7, 1, 1.5, and 2 L/min) provide better body heat preservation during surgical operations.

Hot tearing susceptibility of Fe-20.96Cr-2.13Ni-0.15N-4.76Mn-0.01Mo duplex stainless steel

The hot tearing susceptibility of a Fe-20.96Cr-2.13Ni-0.15N-4.76Mn-0.01 Mo duplex stainless steel was investigated using method of constrained solidification shrinkage in one dimension.An apparatus for realtime measuring the contraction stress and temperature during solidification was developed,which can achieve the in-situ observation of melting and solidification and avoid the large temperature gradient of casting under the condition of pouring.The results show that the contraction stress increases significantly when the core temperature of casting reaches the liquidus temperature.The contraction stress is released when the core temperature of casting reaches 1456°C.At this temperature,the hot tearing susceptibility of duplex stainless steel is the largest.With decreasing the core temperature to 1363°C,the slope of contraction stress increases,which is related to the ferrite-to-austenite transformation.