Helmsbullard4329

Gallium-based room-temperature liquid metals have enormous potential for realizing various applications in electronic devices, heat flow management, and soft actuators. Filling narrow spaces with a liquid metal is of great importance in rapid prototyping and circuit printing. However, it is relatively difficult to stretch or spread liquid metals into desired patterns because of their large surface tension. Here, we propose a method to fabricate a particle-based porous material which can enable the rapid and spontaneous diffusion of liquid metals within the material under a capillary force. Remarkably, such a method can allow liquid metal to diffuse along complex structures and even overcome the effect of gravity despite their large densities. We further demonstrate that the developed method can be utilized for prototyping complex three-dimensional (3D) structures via direct casting and connecting individual parts or by 3D printing. As such, we believe that the presented technique holds great promise for the development of additive manufacturing, rapid prototyping, and soft electronics using liquid metals.Two-dimensional (2D) van der Waals (vdW) heterostructures herald new opportunities for conducting fundamental studies of new physical/chemical phenomena and developing diverse nanodevice applications. In particular, vdW heterojunction p-n diodes exhibit great potential as high-performance photodetectors, which play a key role in many optoelectronic applications. Here, we report on 2D MoTe2/MoS2 multilayer semivertical vdW heterojunction p-n diodes and their optoelectronic application in self-powered visible-invisible multiband detection and imaging. Our MoTe2/MoS2 p-n diode exhibits an excellent electrical performance with an ideality factor of less than 1.5 and a high rectification (ON/OFF) ratio of more than 104. In addition, the photodiode exhibits broad spectral photodetection capability over the range from violet (405 nm) to near-infrared (1310 nm) wavelengths and a remarkable linear dynamic range of 130 dB within an optical power density range of 10-5 to 1 W/cm2 in the photovoltaic mode. Together with these favorable static photoresponses and electrical behaviors, very fast photo- and electrical switching behaviors are clearly observed with negligible changes at modulation frequencies greater than 100 kHz. In particular, inspired by the photoswitching results for periodic red (638 nm) and near-infrared (1310 nm) illumination at 100 kHz, we successfully demonstrate a prototype self-powered visible-invisible multiband image sensor based on the MoTe2/MoS2 p-n photodiode as a pixel. Our findings can pave the way for more advanced developments in optoelectronic systems based on 2D vdW heterostructures.BACKGROUND Warm-up is considered essential to optimize running performance, but little is known about the effect of specific warm-up tasks, specifically in the real competitive context. The current study aimed to verify the acute effects of a warm-up including ballistic exercises in 30m running performance. In addition, a second 30m trial was assessed to better understand the warm-up effects in training/competition. METHODS Twenty-two men (19.32±1.43 years-old) randomly completed the time- trials on separate days and after a typical warm-up (WU), a WU complemented with ballistic exercises (post-activation potentiation - PAP) or no warm-up (NWU). Biomechanical, physiological and psychophysiological variables were assessed. RESULTS The participants were 1.9% faster in the first 30m sprint after WU compared with NWU, mainly increased performance in the first 15m (p=0.03, ES=0.48). WU resulted in greater stride length in the last 15m of the first sprint. PAP did not differ from NWU and WU, despite eight participants performed better after this warm-up. CONCLUSIONS These results highlight the positive effects of warm- up for sprinting, despite failed to evidence positive effects when ballistic exercises are included. In addition, the influence of warm-up in the running technique was highlighted by the changes in the running kinematics and a need for individualization of warm-up procedures.BACKGROUND The aim of this study was to examine the effect of the menstrual cycle on running economy (RE). METHODS Using a repeated-measures design, ten eumenorrheic, trained female runners (age 32 ± 6 yrs, V̇ O2max 59.7 ± 4.7 mL·kg-1·min-1) completed four, weekly, identical sub-maximal and maximal incremental step tests on a treadmill to measure physiological responses across a full menstrual cycle. For phase comparison, the results from the trials that fell in the early follicular (low oestrogen, low progesterone), late follicular (high oestrogen, low progesterone) and mid-luteal (high oestrogen, high progesterone) phases were used. RESULTS There was a significant effect of menstrual cycle phase on RE (p = 0.001), with RE in the mid-luteal (ML) phase being worse than that of the early follicular (EF) (+2.33 mL.kg-1.min-1; p = 0.026) and late follicular (LF) (+2.17 mL.kg-1.min-1; p = 0.011) phases. The ML phase also resulted in elevated core temperature versus the EF (+0.51oC; p = 0.001) and LF (+0.66oC; p = 0.037) phases, and elevated minute ventilation versus the EF phase (+3.83 L.min-1; p = 0.003). find more No significant effects of menstrual cycle phase were found on body mass, heart rate, ratings of perceived exertion, time-to-exhaustion, maximal oxygen consumption, or blood lactate concentration. CONCLUSIONS In the ML phase, which causes increased core temperature and minute ventilation, RE is impaired at exercise intensities that are applicable to training and performance. In physiologically stressful environments, this impairment in RE may have a significant impact on training and performance.BACKGROUND The purpose of this study was to investigate if a post-activation potentiation (PAP) protocol may attenuate the acute interference induced by high- intensity intermittent exercise (HIIE) and on subsequent strength exercise performance in recreationally trained men. METHODS Eleven resistance-trained men (age 25.7±3.7 y) randomly completed three experimental trials Strength Exercise (SE) only (4 sets of maximal number of repetitions at 70% on the 45o leg press); Concurrent Exercise (CE) comprised 5000-m of HIIE at maximal aerobic speed (11 effort and pause ratio) followed by SE protocol; Concurrent Exercise with post-activation potentiation (CE- PAP), comprised the same CE protocol preceded by one set of 2 repetitions at 90% of 1RM on the 45° leg-press before strength exercise. The number of repetitions performed was recorded for each set and total weight lifted was calculated. RESULTS The CE condition induced a greater decrement in volume for the leg press compared to SE and CE-PAP in sets 1 (24±21%; 18±25%), 2 (20±21%; 22±22%), and 3 (19±20%; 25±15%), respectively.