The addition of whey protein to a carbohydrate–electrolyte drink does not influence post-exercise rehydration

The addition of whey protein to a carbohydrate–electrolyte drink has been shown to enhance post-exercise rehydration when a volume below that recommended for full fluid balance restoration is provided. We investigated if this held true when volumes sufficient to restore fluid balance were consumed and if differences might be explained by changes in plasma albumin content. Sixteen participants lost ~1.9% of their pre-exercise body mass by cycling in the heat and rehydrated with 150% of body mass lost with either a 60 g · L^?1 carbohydrate drink (CHO) or a 60 g · L^?1 carbohydrate, 20 g · L^?1 whey protein isolate drink (CHO-P). Urine and blood samples were collected pre-exercise, post-exercise, post-rehydration and every hour for 4 h post-rehydration. There was no difference between trials for total urine production (CHO 1057 ± 319 mL; CHO-P 970 ± 334 mL; P = 0.209), drink retention (CHO 51 ± 12%; CHO-P 55 ± 15%; P = 0.195) or net fluid balance (CHO ?393 ± 272 mL; CHO-P ?307 ± 331 mL; P = 0.284). Plasma albumin content relative to pre-exercise was increased from 2 to 4 h during CHO-P only. These results demonstrate that the addition of whey protein isolate to a carbohydrate–electrolyte drink neither enhances nor inhibits rehydration. Therefore, where post-exercise protein ingestion might benefit recovery, this can be consumed without effecting rehydration.     

Effective body water and body mass changes during summer ultra-endurance road cycling

Because body mass change (ΔM_b) does not represent all water losses and gains, the present field investigation determined if (a) ΔM_b equalled the net effective body water change during ultra-endurance exercise and (b) ground speed and exercise duration influenced these variables. Thirty-two male cyclists (age range, 35–52 years) completed a 164-km event in a hot environment, were retrospectively triplet matched and placed into one of three groups based on exercise duration (4.8, 6.3, 9.6 h). Net effective body water loss was computed from measurements (body mass, total fluid intake and urine excreted) and calculations (water evolved and mass loss due to substrate oxidation, solid food mass and sweat loss), including (ΔEBW_gly) and excluding (ΔEBW) water bound to glycogen. With all cyclists combined, the mean ΔM_b (i.e. loss) was greater than that of ΔEBW_gly by 1200 ± 200 g (P = 1.4 × 10^–18), was similar to ΔEBW (difference, 0 ± 200 g; P = .21) and was strongly correlated with both (R² = .98). Analysis of equivalence indicated that ΔM_b was not equivalent to ΔEBW_gly, but was equivalent to ΔEBW. Due to measurement complexity, we concluded that (a) athletes will not calculate the effective body water calculations routinely and (b) body mass change remains a useful field-expedient estimate of net effective body water change.     

Ad-libitum drinking and performance during a 40-km cycling time trial in the heat

The aim of this study was to investigate if drinking ad-libitum can counteract potential negative effects of a hypohydrated start caused by fluid restriction during a 40-km time trial (TT) in the heat. Twelve trained males performed one 40-km cycling TT euhydrated (EU: no water during the TT) and two 40-km cycling TTs hypohydrated. During one hypohydrated trial no fluid was ingested (HYPO), during the other trial ad-libitum water ingestion was allowed (FLUID). Ambient temperature was 35.2 ± 0.2°C, relative humidity 51 ± 3% and airflow 7 m·s^?1. Body mass (BM) was determined at the start of the test, and before and after the TT. During the TT, power output, heart rate (HR), gastrointestinal temperature, mean skin temperature, rating of perceived exertion (RPE), thermal sensation, thermal comfort and thirst sensation were measured. Prior to the start of the TT, BM was 1.2% lower in HYPO and FLUID compared to EU. During the TT, BM loss in FLUID was lower compared to EU and HYPO (1.0 ± 0.8%, 2.7 ± 0.2% and 2.6 ± 0.3%, respectively). Hydration status had no effect on power output (EU: 223 ± 32 W, HYPO: 217 ± 39 W, FLUID: 224 ± 35 W), HR, gastrointestinal temperature, mean skin temperature, RPE, thermal sensation and thermal comfort. Thirst sensation was higher in HYPO than in EU and FLUID. It was concluded that hypohydration did not adversely affect performance during a 40-km cycling TT in the heat. Therefore, whether or not participants consumed fluid during exercise did not influence their TT performance.     

玻色—爱因斯坦凝聚现象中几个问题的探讨

以理想玻色—爱因斯坦气体为例,从量子统计出发,给出玻色—爱因斯坦凝聚现象的相变点方程和相变点曲线、等温线方程和等温线、两相平衡共存曲线方程和两相平衡共存曲线及克劳修斯—克拉伯龙方程,了解这些对于全面掌握玻色—爱因斯坦凝聚现象是非常有用的.     

The Influence of Hydration on Anaerobic Performance

This review examines the influence of dehydration on muscular strength and endurance and on single and repeated anaerobic sprint bouts. Describing hydration effects on anaerobic performance is difficult because various exercise modes are dominated by anaerobic energy pathways, but still contain inherent physiological differences. The critical level of water deficit (～ 3–4%; mode dependent) affecting anaerobic performance is larger than the deficit (～ 2%) impairing endurance performance. A critical performance-duration component (> 30 s) may also exist. Moderate dehydration (> 3% body weight; precise threshold depends on work/recovery ratio) impairs repeated anaerobic bouts, which place an increased demand on aerobic metabolism. Interactions between dehydration level, dehydration mode, testing mode, performance duration, and work/recovery ratio during repeated bouts make the dehydration thresh-old influencing anaerobic performance mode dependent.     

Insect-Infested Wood Remediation by Microwave Heating and Its Effects on Wood Dehydration: A Case Study of Hylotrupes bajulus Larva

Wood artefacts are subject to damage by biologic infestations due to bacteria, insects, and fungal species. One of the worst feared attacks is due to the xylophagous insects whose larvae feed on wood by boring galleries, at the expense of building timbers and worked woods. These beetles are responsible for daily destruction of the world’s wooden cultural heritage, and their elimination has been always a big problem for conservation of wood. The need to avoid the use of chemical methods in conservation for pest control has led to the development of various non-chemical, non-toxic treatments. Among these, heating with microwaves (MW) seems to be one of the most promising, since it has already shown its high efficacy in destroying pests. Insect-infested wood remediation by MW heating in conservation is based on the larger thermal increment induced in larvae than in wood, due to their different dielectric permittivity in the GHz frequency range. However, the side effects that may occur due to MW heating of wood, such as dehydration, have never been discussed so far. Here we study the possible application of microwave heating as a remediation method for wood samples infested by the larvae of the insect Hylotrupes bajulus. We show that it is possible to set up exposure conditions able to achieve 100% of larvae death and that are sufficiently mild not to induce significant dehydration of the exposed wood from which shrinkage effects may derive. Indeed, under these conditions, MW-induced wood dehydration on cubic and parallelepiped sweetgum samples can be kept under control and to percentages as low as 0.4% (w/w).     

计算机语音合成技术及其应用

根据当前相关研究的发展，阐述了语音合成技术的基本原理，基于不同的要求和目的所用的实现方法，以及语音合成技术的产品在生活中的广泛应用．     

苄醇催化脱水制取苄醚的研究

以单质碘为催化剂直接由苄醇催化脱水生产苄醚．考察了影响收率的因素．其最佳条件为：苄醇：催化剂：带水剂=2mol：1．2g：40ml。反应在回流温度下进行(158～160℃)。反应时间4h。产率91．2％．     

Urine specific gravity as an indicator of dehydration in Olympic combat sport athletes; considerations for research and practice

Urine specific gravity (U_SG) is the most commonly reported biochemical marker used in research and applied settings to detect fluid deficits in athletes, including those participating in combat sports. Despite the popularity of its use, there has been a growing debate regarding the diagnostic accuracy and the applicability of U_SG in characterizing whole-body fluid status and fluctuations. Moreover, recent investigations report universally high prevalence of hypohydration (～90%) via U_SG assessment in combat sport athletes, often in spite of stable body-mass. Given the widespread use in both research and practice, and its use in a regulatory sense as a ‘hydration test’ in combat sports as a means to detect dehydration at the time of weigh-in; understanding the limitations and applicability of U_SG assessment is of paramount importance. Inconsistencies in findings of U_SG readings, possibly as a consequence of diverse methodological research approaches and/or overlooked confounding factors, preclude a conclusive position stand within current combat sports research and practice. Thus the primary aim of this paper is to critically review the literature regarding U_SG assessment of hydration status in combat sports research and practice. When taken on balance, the existing literature suggests: the use of laboratory derived benchmarks in applied settings, inconsistent sampling methodologies, the incomplete picture of how various confounding factors affect end-point readings, and the still poorly understood potential of renal adaptation to dehydration in combat athletes; make the utility of hydration assessment via U_SG measurement quite problematic, particularly when diet and training is not controlled.     

乙醇脱水中取代和消除竞争的讨论

从理论上讨论了乙醇脱水反应中,温度对取代和消除竞争的影响。