The purpose of this study was to investigate the effects of 8-week whole-body vibration (WBV) training on running economy (RE) and power performance. Twenty-four male collegiate athletes were recruited and randomly assigned to experimental (WBV) and placebo (PL) groups. The WBV subjects performed semisquat vibration training (30 Hz, ±1-2 mm, 3 times per week), whereas PL subjects performed identical training without vibration. The isometric maximum voluntary contraction tests were used to evaluate maximal isometric force (F(max)) and rate of force development (RFD) of lower extremities, before and after the intervention, and RE was measured on a level treadmill at 3 velocities (2.68, 3.13, and 3.58 m·s(-1)). The F(max) of the lower leg (plantar flexion, from 80.8 ± 24.5 to 99.0 ± 33.9 N·m, p < 0.05, η(2) = 0.567; dorsiflexion, from 38.1 ± 6.5 to 43.0 ± 7.7 N·m, p < 0.05), and the RFD of 0-200 milliseconds during plantar flexion (from 186.0 ± 69.2 to 264.6 ± 87.2 N·m·s(-1), p < 0.05, η(2) = 0.184) were significantly increased in the WBV group after training. The averaged RE values for the 3 running velocities were significantly improved after WBV training (pretraining vs. posttraining, 4.31 ± 0.33 vs. 4.65 ± 0.34 m·ml(-1)·kg(-1), p = 0.001, η(2) = 0.654); however, no significant differences were found in the PL group (pretraining vs. posttraining, 4.18 ± 0.26 vs. 4.26 ± 0.44 m·ml(-1)·kg(-1), p = 0.476). The WBV training significantly improved RE at selected speeds (∼5.0-8.5%, p < 0.05). These results indicated that short-term WBV training could be an effective stimulus to enhance RE and lower extremity power performance in competitive athletes.
The novel polymer poly(5-methylenebenzotriazol-N-yl), denoted BTA-poly, was investigated for the protection of copper by electrochemical studies and weight loss measurements. The electrochemical measurements were compared to weight loss measurements and satisfactory results were obtained.Compared with benzotriazole, which is one of the best corrosion inhibitors for copper, BTA-poly achieves good protection under the same test conditions. Due to the rapid adsorption of BTA-poly onto copper, its corrosion-inhibition efficiency can be controlled by varying the concentration. The protecting effects of the polymers were studied in a sodium chloride solution using electrochemical measurements and an immersion test. The surface characteristics of the polymer-modified copper were analyzed via X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). These results show that BTA-poly can be easily adsorbed onto the copper surface via self-assembly to achieve excellent anticorrosion/antioxidation effects.
Due to lack of desirable mechanical properties of silicon substrate; the current trend of
micro-fabrication technology is towards metallic materials. In this study, the electrochemical micromachining
(EMM) technology is developed to fabricate micro-scale flow channels on thin metallic
316L stainless steel plate. The cathode electrode, the tool, is the mirror image of flow channels. It
was produced by the MEMS and UV-LIGA technology and the size is 200μm in width and 500μm
in height for the intension to fabricate a serpentine flow channel of 200μm in both depth and width.
Because of the electrode size, the process control parameters and geometrical features surpassed
conventional and CMOS methods. The flow channels on 0.6mm thick SS 316L plates were
fabricated by EMM process within 30 seconds with effective area of 625mm2. The dimensions of
flow channel were varying from 1504m to 5004m in width and about 2004m in depth. The results
demonstrate the EMM technology produces good quality metallic flow channels efficiently.
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