海洋环境出水漆器残片的几种加固技术实践

在"南海Ⅰ号"试发掘中出水了一批漆器残片.漆器作为生活中的实用器,在宋代的使用与瓷器一样十分普遍,根据史料记载,宋代的漆器也作为海洋贸易的主要货物销往海外.由此可以预见"南海Ⅰ号"沉船中存有一定数量漆器文物的可能性极大,为了研究海洋环境出水漆器的保护技术,以该批漆片作为实验研究材料,分别采用不同加固技术,选取部分残片进行了几种加固方法的实践研究.     

Evaluation of pre-game hydration status,heat stress,and fluid balance during professional soccer competition in the heat

Abstract

In this study, we assessed initial hydration status (stadium arrival urine specific gravity), fluid balance (pre- and post-game nude body weight, fluid intake, urine collection), and core temperature changes (pre-game, half-time, post-game) during a professional soccer game. We monitored 17 male players (including goalkeepers) between arrival at the stadium and the end of the game (3 h), playing at 34.9°C and 35.4% relative humidity, for an average wet bulb globe temperature (WBGT) heat stress index of 31.9°C. Data are reported as mean±standard deviation (range). Initial urine specific gravity was 1.018±0.008 (1.003–1.036); seven players showed urine specific gravity ≥ 1.020. Over the 3 h, body mass loss was 2.58±0.88 kg (1.08–4.17 kg), a dehydration of 3.38±1.11% body mass (1.68–5.34% body mass). Sweat loss was 4448±1216 ml (2950–6224 ml) versus a fluid intake of 1948±954 ml (655–4288 ml). Despite methodological problems with many players, core temperatures ≥ 39.0°C were registered in four players by half-time, and in nine players by the end of the game. Many of these players incurred significant dehydration during the game, compounded by initial hypohydration; thermoregulation may have been impaired to an extent we were unable to measure accurately. We suggest some new recommendations for soccer players training and competing in the heat to help them avoid substantial dehydration.     

Measures of cardiac autonomic control in women with differing volumes of physical activity

Abstract

The most recent (1996) drinking guidelines of the American College of Sports Medicine (ACSM) propose that athletes should drink “as much as tolerable” during exercise. Since some individuals can tolerate rates of free water ingestion that exceed their rates of free water loss during exercise, this advice has caused some to overdrink leading to water retention, weight gain and, in a few, death from exercise-associated hyponatraemic encephalopathy. The new drinking guidelines of the International Olympic Committee (IOC), recently re-published in this Journal, continue to argue that athletes must drink enough to replace all their weight lost during exercise and to ingest sodium chloride since sodium is “the electrolyte most critical to performance and health”. In this rebuttal to that Consensus Document, I argue that these new guidelines, like their predecessors, lack an adequate, scientifically proven evidence base. Nor have they been properly evaluated in appropriately controlled, randomized, prospective clinical trials. In particular, these new guidelines provide erroneous recommendations on five topics.

If novel universal guidelines for fluid ingestion during exercise are to be promulgated by important international bodies including the IOC, they should first be properly evaluated in appropriately controlled, randomized, prospective clinical trials conducted under environmental and other conditions that match those found in “out-of-doors” exercise. This, and the potential influence of commercial interests on scientific independence and objectivity, are the two most important lessons to be learned from the premature adoption of those 1996 ACSM drinking guidelines that are not evidence-based. These concerns need to be addressed before the novel IOC guidelines are accepted uncritically. Otherwise the predictable consequences of the premature adoption of the 1996 ACSM guidelines will be repeated.     

Fluid balance of elite Brazilian youth soccer players during consecutive days of training

Abstract

In this study we investigated pre-training hydration status, fluid intake, and sweat loss in 20 elite male Brazilian adolescent soccer players (mean ± s: age 17.2 ± 0.5 years; height 1.76 ± 0.05 m; body mass 69.9 ± 6.0 kg) on three consecutive days of typical training during the qualifying phase of the national soccer league. Urine specific gravity (USG) and body mass changes were evaluated before and after training sessions to estimate hydration status. Players began the days of training mildly hypohydrated (USG > 1.020) and fluid intake did not match fluid losses. It was warmer on Day 1 (33.1 ± 2.4°C and43.4 ± 3.2% relative humidity; P < 0.05) and total estimated sweat losses (2822 ± 530 mL) and fluid intake (1607 ± 460 mL) were significantly higher (P < 0.001) compared with Days 2 and 3. Data also indicate a significant correlation between the extent of sweat loss and the volume of fluid consumed (Day 1: r = 0.560, P = 0.010; Day 2: r = 0.445, P = 0.049; Day 3: r = 0.743, P = 0.0001). We conclude that young, native tropical soccer players arrive hypohydrated to training and that they exhibit voluntary dehydration; therefore, enhancing athletes' self-knowledge of sweat loss during training might help them to consume sufficient fluid to match the sweat losses.     

催化反应用简易管式加热装置的设计

为配合催化剂制备剂及活性检测教学实验、课程设计及科研实验，设计、加工并组装了由加热部分、精密控温部分和反应装置组成的小型管式反应装置，普适于实验室各种温度条件下的非均相催化反应，尤其适用于气固相体系，并可实现连续操作。以醉脱水成烯反应为例进行了使用效果检验。结果表明：该装置安装简单，操作方便，能准确控制反应体系温度；高低温状态下性能均比较稳定，且控温灵敏。