ABSTRACT
This article reviewed the changes of ankle muscle strength after lower limb joint injuries and the isokinetic test mode which could reflect this characteristic better. The varus plantarflexion strength decreased significantly after plantarflexion injury of ankle joint. The dorsiflexor strength of ankle joint could not reach the level of the healthy side for a long time after anterior cruciate ligament rupture and Achilles tendon injury. Ankle isokinetic muscle test included testing direction, muscle contraction form and testing speed. It is meaningful to test varus/valgus and plantar/dorsal flexion in ankle joint sprain and functional ankle instability; however, the muscle contraction form and testing speed have little effect on the result.
ABSTRACT
<p><b>OBJECTIVE</b>To find a suitable method for detecting SiO2 in quartz sand and to analyze the influencing factors on infrared spectroscopic determination of the content of free silica in quartz sand.</p><p><b>METHODS</b>The infrared spectroscopy was used to detect the free silica content of quartz sand, the various factors of influencing the results were analyzed and the control scheme was proposed.</p><p><b>RESULTS</b>The number of particles less than 5 um and the proportion of free silica content increased with the grinding time. When the grinding time was 10-20 min, the results of detecting the free silica content tended to be stable. When the ashing temperature was below 550 degrees C, there was no effect on the free silica content. Although the silica content decreased slightly at ashing temperature 600 degrees C as compared to ashing temperature 550 degrees C, the difference of the free silica content between 550 degrees C and 600 degrees C was not significant (P > 0.05). When the ashing temperature was 600 degrees C, the free silica content in quartz sand samples did not change obviously in 1 h (F = 4.231, P > 0.05). The free silica content in quartz sand samples decreased significantly at 2 h of ashing time, as compared with 2 h of ashing time (F = 10.231, P < 0.05). The average content of free silica was 88.56% +/- 5.75% by pyrophosphate determination, which was significantly higher than that (21.23% +/- 11.25%) by infrared determination (P < 0.05). There was no significant correlation of the average content of free silica between pyrophosphate determination and infrared determination (r = 0.411, P > 0.05).</p><p><b>CONCLUSION</b>The free silica contents detected by pyrophosphate determination were significantly higher than those detected by infrared determination for the same quartz sand samples. It is suggested that the method of detecting the free silica contents in quartz sand samples prefers the pyrophosphate determination to infrared determination.</p>