带呼吸囊管式背心抗荷服的热负荷测定

测定5名志愿被试者在34－35℃环境中着用带呼吸囊管式背心抗荷服时的加权平均皮肤温度（TS）、囊下局部皮肤温度、口腔温度等指标。结果表明，与不带呼吸囊组比较，管式背心加呼吸囊后除局部皮肤温度略有升高（1．2±0．1℃）外，其他各项指标均无显著差别（P＞0．05）。初步认为，在环境热负荷强度不大时，该装备不会引起飞行员显著热应激。     

三种液冷装备致冷效果的医学研究

本文研究了在环境温度为45℃、露点温度为28℃,受试者处于运动和安静两种状态下,液冷帽、液冷背心和简易液冷服的致冷效果。结果表明,几种液冷装备均具有明显的致冷效果和显著的隔热作用。致冷效能以简易液冷服最大,其次为液冷背心和液冷帽。相反,致冷效率液冷帽最高,其次为液冷背心和简易液冷服。由于被致冷部位的解剖和生理机能的不同,致冷时生理反应并不一样。致冷躯干时,皮肤温度达稳定状态的时间比致冷头、颈部时间约长1小时,并且前者皮肤温度也较后者低4℃。     

抗荷正压呼吸时不同囊面积背心代偿性能的比较

目的探讨缩小代偿背心的囊覆盖面积是否仍能保证抗荷正压呼吸（ＰＢＧ）时胸部的代偿性能。方法在离心机上，６名受试者分别穿大囊（Ｌ）、中囊（Ｍ）或胸背囊（ＴＢ）代偿背心、充气，在＋５．５ＧＺ时进行４．８ｋＰａ的ＰＢＧ，在＋６．５ＧＺ进行８．０ｋＰａ的ＰＢＧ；或穿ＴＢ代偿背心、不充气，在＋５．５ＧＺ进行４．８ｋＰａ的ＰＢＧ，在＋６．０ＧＺ进行６．４ｋＰａ的ＰＢＧ。测量的指标包括，抗荷服压（Ｐｓ）、面罩压（Ｐｍ）、胸部代偿压（Ｐｔ）、呼吸频率（Ｒ）、心率（ＨＲ）及主观评分。结果当受试者分别穿Ｌ、Ｍ或ＴＢ这三种代偿背心、充气时，均能很好耐受所进行的ＰＢＧ。各项指标在Ｌ、Ｍ及ＴＢ这三种代偿背心间并无显著性差别（Ｐ＞０．０５）。穿ＴＢ代偿背心、不充气时，受试者对所进行的ＰＢＧ仍可耐受。结论采用囊覆盖面积比较小的Ｍ代偿背心已可满足ＰＢＧ时对胸部实施有效代偿的需要；穿ＴＢ代偿背心、不充气时，受试者也能较好地耐受６．４ｋＰａ的ＰＢＧ。在＋ＧＺ作用时将代偿背心的囊覆盖面积适当缩小是可能的。     

飞行员新型通风背心散热性能评价

目的设计一款通风背心,降低战斗机飞行员的热应激水平。方法新型背心具有以下特征:扁平的通风管,分支管纵向分布且有高强度材料支撑,通风管里侧有小孔可吹出气体。并设计了一个热舒适性实验对人体生理参数(心率、温度)进行了测量。结果通风背心对躯干的降温效果非常明显,对降低核心体温也能起到一定的作用。结论该设计可以提高飞行员在高温环境下的持续作战能力,并提高其关键部位的热舒适性。     

高温环境下局部体表降温对心率的影响

受试者为７名健康男性青年，观察其穿水冷背心在高温环境下的心率变化。在环境温度为３５、４０和４５℃条件下，分别配以水温２４、２７和３０℃的水冷背心。生理参数观测表明，胸背部体表降温可使心搏增加速度减慢。与对照组相比，高温下有效工作时间明显延长，不适症状减轻，体温升高幅度也较小。实验提示，胸背部体表降温方法可明显提高高温环境下的工作效率，其主要因素可能是减低了机体功心率加速反应。     

YLJY—I型医用物理降温仪临床评价

目的评价YLJY-I型医用物理降温仪局部降温和全身降温效果。方法采用开放、平行对照的试验方法，将60名受试者随机分入试验组和对照组，分别测量两组局部温度和整体温度并评价降温效果。结果资料显示，试验组与对照组评价指标具有可比性。与对照组相比，试验组局部降温效果显著，而整体降温效果不显著。结论YLJY-I型医用物理降温仪在临床应用过程中安全，有效，可以适用于临床需要局部降温的患者。     

新型高空海上联合救生服的温度生理学评价

目的 评价新型高空海上联合救生服的热负荷及防寒性能.方法 ①隔热值测定：A组＋B组装备配穿于暖体假人上,测定其隔热值.②热负荷试验：5名受试者配穿A组装备,在25℃气温环境试验60 min,测定热应激反应.③防寒性能试验：2名受试者配穿A组＋B组装备,在-30℃气温环境试验60 min,评定其防寒性能.结果 服装隔热值为4.22 clo;受试者在25℃试验环境60 min,产生轻度热应激;在-30℃、无风环境试验60 min,受试者无明显全身不适（冷）反应.结论 新型高空海上联合救生服的热负荷很大,在25℃左右环境中,为了维持飞行员良好的工效,穿着时间不宜超过30 min;建议该装备在重新设计时,适当减少保暖材料.     

YLJY-Ⅰ型医用物理降温仪临床评价

目的 评价YUY-Ⅰ型医用物理降温仪局部降温和全身降温效果. 方法 采用开放、平行对照的试验方法,将60名受试者随机分入试验组和对照组,分别测量两组局部温度和整体温度并评价降温效果. 结果 资料显示,试验组与对照组评价指标具有可比性.与对照组相比,试验组局部降温效果显著,而整体降温效果不显著. 结论 YUY-I型医用物理降温仪在临床应用过程中安全,有效,可以适用于临床需要局部降温的患者.     

身着通风防护背心以减少直升机飞行员所受的热负荷

直升机飞行员常暴露于周期性的高热压力环境中，尤其当他们穿着救生衣的时候。因此，在2小时的模拟飞行中，用一种通风防护背心来减小直升机飞行员所受的热负荷，可以测试出来这种背心的降温效果。假设通风防护背心可以减小飞行员所受的热压力。五名男性飞行员和一名女性飞行员在三种不同的条件下在模拟器中飞行2小时，这三种条件分别为：不通风条件下的环境湿球温度分别为15℃、32℃；通风条件下的环境湿球温度为32℃。身着通风防护背心在很大程度上减少了直肠温度的升高，缓解了热负荷。     

载人航天器预冷温度的热生理学探讨

目的探讨载人舱室适宜的预冷温度 ,以预防或减缓发射、返回段航天器内高温对人体的不利影响。方法 5名健康男性青年按着航天服时不通风和以通风流率 1 0 0L/min(STPD)通风等不同着装条件 ,在舱温 1 5、l0、5℃环境中进行 2 5人次实验。测量直肠温度 (Tr)、平均皮温 (Tsk)和平均体温 (Tb)等热生理指标。结果在舱温 1 5℃航天服通风和不通风状态 ,实验 2h内人体直肠温度降低不显著 (从初始值 37.0± 0 .2℃降为 36.7± 0 .3℃ ) ,平均体温、平均皮温显著降低 (P <0 .0 5) ,受试者有局部的冷紧张 ;而在舱温和通风温度 1 0℃时 ,受试者热生理指标随时间延长不断降低 ,直肠温度从 37.0± 0 .3℃显著下降至 36.3± 0 .3℃ ,Tsk、Tb 显著低于初始值 (P <0 .0 5) ,受试者有全身性冷紧张。结论按人体热舒适状态无显著改变的要求 ,航天器座舱预冷后维持 1 5℃气温对人体较为适宜。     

Helicopter cooling of heatstroke victims

Theoretical and clinical evidence suggests that traditional ice water immersion is not the best therapy for heatstroke. We treated three patients with serious heatstroke using the downdraft from a light utility helicopter to dissipate heat primarily by evaporation and convection. The speed of cooling was substantially better than that reported in prior clinical series.     

Self-paced exercise performance in the heat with neck cooling,menthol application,and abdominal cooling

Objectives

To investigate whether the exercise performance benefits with neck cooling in the heat are attributable to neck-specific cooling, general body cooling, a cooler site-specific thermal perception or a combination of the above.

Skin temperature feedback optimizes microclimate cooling

INTRODUCTION: A novel pulsed cooling paradigm (PCskin) integrating mean skin temperature (Tsk) feedback was compared with constant cooling (CC) or time-activated pulsed cooling (PC). METHODS: Eight males exercised while wearing personal protective equipment (PPE) in a warm, dry environment (dry bulb temperature: 30 degrees C; dew-point temperature: 11 degrees C) in each of the tests. Treadmill exercise was performed (approximately 225 W x m(-2)) for 80 min. A liquid cooling garment (LCG) covered 72% of the body surface area. Core temperature (Tc), local skin temperatures, heart rate, inlet and outlet LCG perfusate temperatures, flow, and electrical power to the LCG and metabolic rate were measured during exercise. RESULTS: At 75 min of exercise Tsk was higher (33.9 +/- 0.2 degrees C) in PCskin, than in PC (33.1 +/- 0.5 degrees C) or CC (32.0 +/- 0.6 degrees C) and PC > CC. The changes in Tc and heart rate during the tests were not different. Tc at 75 min was not different among the cooling paradigms (37.6 +/- 0.3 degrees C in PCskin, 37.6 +/- 0.2 degrees C in PC and 37.6 +/- 0.2 degrees C in CC). Heart rate averaged 124 +/- 10 bpm in PCskin, 120 +/- 9 bpm in PC and 117 +/- 9 bpm in CC. Total body insulation (degrees C x W(-1) x m(-2)) was significantly reduced in PCskin (0.020 +/- 0.003) and PC (0.024 +/- 0.004) from CC (0.029 +/- 0.004). Electrical power in PCskin was reduced by 46% from CC and by 28% from PC. DISCUSSION/CONCLUSION: Real-time Tsk feedback to control cooling optimized LCG efficacy and reduced electrical power for cooling without significantly changing cardiovascular strain in exercising men wearing PPE.     

Physiological adjustments of facial cooling during exercise

Physiological and metabolic output responses to facial cooling during a graded maximal exercise and a prolonged submaximal exercise lasting 30 min at 65% VO2 max were investigated in five male subjects. Pedalling on a cycle ergometer was performed both with and without facial cooling (10 degrees C, 4.6 M.S-1). Facial cooling at the end of greated maximal exercise apparently had no effect on plasma lactate (LA), maximal oxygen consumption (VO2 max), maximal heart rate (HR max), rectal temperature (Tre), work load, lactate threshold (LT), ventilatory threshold (VT) and onset of blood lactate accumulation (OBLA). However, the response to facial cooling after prolonged submaximal exercise is significantly different for heart rate and work load. The results suggest that facial wind stimulation during maximal exercise does not produce a stress high enough to alter the metabolic and physiological responses.     

Physiological and performance benefits of halftime cooling

This study examined the effect of a 10-min, halftime cooling application on physiological and psychological parameters known to affect performance. Fourteen volunteers (10 male, 4 female) completed two randomised trials 48 hr to 7 days apart. Trials consisted of a 1-hr cycling protocol: 30 min at 75% VO2max followed by 10 min cooling (application of a cooling jacket) or passive recovery (control), and a second 30-min exercise bout consisting of 20 min at 75% VO2max, immediately followed by a 10-min maximal effort, where work was measured as energy expended (kJ). Performance of the 10-min maximal intensity phase tended to improve (171.5 +/- 30.4 kJ vs 165.4 +/- 29.2 kJ, p = 0.087) following the cooling trial. Heart rate during the 5th min of the maximal effort, (183 +/- 9 beats.min(-1) vs 180 +/- 7 beats.min(-1), p = 0.024), blood lactate concentration at 6 min post-exercise (9.3 +/- 3.1 mmolxL(-1) vs 7.9 +/- 3.2 mmolxL(-1), p = 0.007), rating of perceived exertion at the 20th min post-halftime recovery (15 +/- 2 vs 16 +/- 2, p = 0.042), and subjective rating of feelings and emotions differed between the cooling and control conditions. Sweat loss, core and mean skin temperature and rating of thermal sensation failed to differ significantly between conditions. Halftime cooling tended to result in greater aerobic performance. Psychological assessment revealed a dramatic placebo effect from the cooling application confounding these results. Furthermore, the cooling intervention failed to induce any significant thermoregulatory effects.     

Evaluation of three commercial microclimate cooling systems

Three commercially available microclimate cooling systems were evaluated for their ability to reduce heat stress in men exercising in a hot environment while wearing high insulative, low permeability clothing. Five male volunteers performed three 180-min experiments (three repeats of 10 min rest, 50 min walking at 440 watts) in an environment of 38 degrees C dry bulb (Tdb), 12 degrees C dew point (Tdp). The cooling systems were: 1) ILC Dover Model 19 Coolvest (ILC), mean inlet temperature 5.0 degrees C; 2) LSSI Coolhead (LSSI), mean inlet temperature 14.5 degrees C; and 3) Thermacor Cooling Vest (THERM), mean inlet temperature 28.3 degrees C. Endurance time (ET), heart rate (HR), rectal temperature (Tre), mean skin temperature (Tsk), sweating rate (SR), rated perceived exertion (RPE), and thermal sensation (TS) were measured. A computer model prediction of ET with no cooling was 101 min. ET was greater (p less than 0.01) with ILC (178 min) than THERM (131 min) which was greater (p less than 0.01) than LSSI (83 min). The subjects self terminated on all LSSI tests because of headaches. Statistical analyses were performed on data collected at 60 min to have values on all subjects. There were no differences in HR, Tre, SR, or TS values among the cooling vests. The subjects' Tsk was lower (p less than 0.05) for the LSSI than THERM; and RPE values were higher (p less than 0.05) for LSSI than the other two vests. These data suggest an improved physiological response to exercise heat stress with all three commercial systems with the greatest benefit in performance time provided by the ILC cooling system.     

Energy loss due to radiation in postmortem cooling

With the help of the law of Stefan and Boltzmann and a model for the cooling of exposed skin derived from the data of Lyle and Cleveland [7], the radiation energy loss E_R can be calculated according to the following formula: where ɛ represents the emissivity of the skin (0.98), σ the Stefan-Boltzmann constant, A_R the radiating surface area, T_S(0) the skin temperature at death, T_E the environmental temperature and Z′ = 0.1017 the gradient of the skin temperature curve. Additionally, an energy loss due to conduction and convection E_C has to be taken into account. Comparing the energy losses due to radiation, conduction and convection with the decrease E_T of the thermal energy in the body, calculated from mean heat capacity (3.45 kJ/(kg °K)), body mass and decrease of mean body temperature, there is a surplus of energy in the very early postmortem period, which can be explained only by an internal source of energy E_I. Alltogether the following balance equation can be formulated: Since the body temperature decreases in the early postmortem period, E_I can be estimated by: E_I(t) ≥ max (E_R(t) – E_T(t), 0). The values obtained range up to 500 kJ for a medium sized (175 cm), medium weight (75 kg) body at an environmental temperature of 5 °C and are compatible with estimations of Lundquist [6] for supravital energy production by breakdown of glycogen. Received: 13 August 1998 / Received in revised form: 10 November 1998     

Production of no-carrier-added Be from target cooling water

Beryllium-7, a monoenergetic photon emitter, is present as a by-product in a no-carrier-added (NCA) form at the BLIP from proton activation of the water which is used to cool targets. This report describes its recovery and purification.     

Energy loss due to radiation in postmortem cooling

Conduction and convection are assumed to account for most of the energy loss from the dead body to the (cooler) environment. There are no quantitative estimations in the literature for the contribution of radiation to heat loss. The aim of the present paper was to estimate the radiation energy loss in postmortem cooling. The Stefan-Boltzmann law is used and combined with a single-exponential model for the cooling process of the skin derived from experimental data of Lyle and Cleveland (1956). The influence of various factors (e.g. skin temperature, environmental temperature, body mass and body height) on the amount of radiation emitted was investigated. The radiation energy is quantitatively described as a function of time. The radiation energy loss ranged from approximately 200 kJ in small (165 cm) and lean (50 kg) bodies at room temperature (20 °C) to approximately 600 kJ in tall (185 cm) and over-weight (100 kg) bodies at outdoor temperature (5 °C) in the first hour postmortem. Received: 4 February 1998 / Received in revised form: 12 March 1998