Research progress of transparent conducting ZnO:Al(ZAO)films

Owing to both of its high carrier concentration and large band gap,ZnO:Al(ZAO)films which is an n-type degenerate semiconductor,exhibits low resistance and high transmittance in the visible range.This work studies the crystal structure,optical and electrical properties and preparation methods of ZAO films,and discusses the existing problems and application prospective of ZAO films.     

Simulated tennis matchplay in a controlled environment

The aim of this study was to develop an exercise protocol to simulate tennis matchplay on a 'category 2' surface. Match analyses were used to form the basis for the design of the protocol. The protocol involved playing against a tennis ball serving machine. Part A of the protocol comprised 92 min 46 s of simulated tennis matchplay; Part B consisted of continuous hitting to the point of 'volitional fatigue' or when the required hitting frequency for two consecutive ball feeds could no longer be maintained. Ten elite tennis players (5 males, 5 females) volunteered to participate in the study, which was performed on an indoor tennis court (Matchplay?, En-Tout-Cas)?. Their age, body mass and estimated maximal oxygen uptake were as follows: males, 21.7±1.0 years, 73.6±2.6 kg and 58.0±1.7 ml?·?kg^?1?·?min^?1, respectively; females, 21.9±1.3 years, 62.3±2.0 kg and 42.2±0.7 ml?·?kg?·?min^?1, respectively (mean±). Heart rate, change in body mass and time to volitional fatigue were monitored. The heart rate responses of the participants to the simulated matchplay (range: 140-157 beats?·?min^?1, 73-81% peak heart rate) were consistent with the results of previous studies, for 'actual' matchplay. This protocol was successful in simulating similar physiological responses in Part A to 'actual' matchplay on a 'category 2' surface, in a controlled environment; it was also a sensitive evaluation tool of skilled performance in Part B. The current protocol may be used as a baseline protocol for studying the influence of, for example, training and dietary intervention on performance.     

四种作用力的大统一场论已近在眼前

伟大的科学家Einstein曾说他感觉到自然界有统一性,他说“这是一种壮丽的感觉”,他首先提倡研究四种作用力的统一场论,提出过“黎曼空间几何统一场论”[1,2],未能成功。后来也有人提出“量子统一场论”[3],“规范统一场论”[4],“弱-电统一场论”[5,6,7],“三种力统一场论”[8]     

从夸饰与虚构的运用看《战国策》的文学价值

具有重要史料价值的《战国策》,因大量纵横游说之辞中对夸饰与虚构手法的运用而富有浓厚的学色彩,其夸饰与虚构的体现形式多种多样。《战国策》的学成就,在先秦史传学中,许多方面具有独创性,对后世学的发展产生过深元的影响。     

A comparison of methods to determine maximal accumulated oxygen deficit in running

The aim of this study was to compare maximal accumulated oxygen deficit (hereafter O2 deficit) estimated from the methods of Whipp et al. (1986), Medbo et al. (1988), and Hill et al. (1998) to determine whether they agree sufficiently to be used interchangeably. Nineteen moderately to highly trained endurance runners first performed an incremental test to exhaustion for the determination of maximal oxygen uptake ([Vdot]O(2max)) and peak treadmill speed, followed by six randomly ordered constant-speed tests at 95, 100, 105, 110, 110, and 120% of peak treadmill speed. All tests were separated by at least 72 h and were performed within 4 weeks. The method of Whipp produced an O(2) deficit estimate that was lower than that derived from the method of Hill or Medbo (bias +/- 95% limits of agreement: -29.6 +/- 36.6 and -26.1 +/- 32.8 ml . kg(-1), respectively; P < 0.001). The O2 deficit did not differ between the methods of Hill and Medbo (bias +/- 95% limits of agreement: 3.5 +/- 41.6 ml . kg(-1); n.s.). However, poor correlations (0.21 < r < 0.33; n.s.) together with wide limits of agreement between O2 deficit estimates (70 - 80% of the mean response) clearly question using these methods interchangeably.     

A comparison of methods to determine maximal accumulated oxygen deficit in running

Abstract

The aim of this study was to compare maximal accumulated oxygen deficit (hereafter O₂ deficit) estimated from the methods of Whipp et al. (1986 Whipp, B. J., Ward, S. A. and Wasserman, K. 1986. Respiratory markers of the anaerobic threshold. Advances in Cardiology, 35: 47–64. [Crossref], [PubMed] , [Google Scholar]), Medbo et al. (1988 Medbo, J. I., Mohn, A. C., Tabata, I., Bahr, R., Vaage, O. and Sejersted, O. M. 1988. Anaerobic capacity determined by maximal accumulated O₂ deficit. Journal of Applied Physiology, 64: 50–60. [PubMed], [Web of Science ®] , [Google Scholar]), and Hill et al. (1998 Hill, D. W., Ferguson, C. S. and Ehler, K. L. 1998. An alternative method to determine maximal accumulated O₂ deficit in runners. European Journal of Applied Physiology, 79: 114–117. [Crossref], [Web of Science ®] , [Google Scholar]) to determine whether they agree sufficiently to be used interchangeably. Nineteen moderately to highly trained endurance runners first performed an incremental test to exhaustion for the determination of maximal oxygen uptake ([Vdot]O_2max) and peak treadmill speed, followed by six randomly ordered constant-speed tests at 95, 100, 105, 110, 110, and 120% of peak treadmill speed. All tests were separated by at least 72 h and were performed within 4 weeks. The method of Whipp produced an O₂ deficit estimate that was lower than that derived from the method of Hill or Medbo (bias ± 95% limits of agreement: ?29.6 ± 36.6 and ?26.1 ± 32.8 ml · kg^?1, respectively; P < 0.001). The O₂ deficit did not differ between the methods of Hill and Medbo (bias ± 95% limits of agreement: 3.5 ± 41.6 ml · kg^?1; n.s.). However, poor correlations (0.21 < r < 0.33; n.s.) together with wide limits of agreement between O₂ deficit estimates (70 – 80% of the mean response) clearly question using these methods interchangeably.