Hydration of Single Crystals of Dipalmitoylphosphatidylcholine

Optical birefringence and x-ray measurements are reported for single crystals $(0.5 mm \times 2 mm \times 5 \mu m)$ of dipalmitoylphosphatidylcholine as a function of temperature and relative humidity. Large single crystals grown in $CHCl_3$/acetone at a low water concentration undergo an irreversible phase transformation at $20^{\circ}C$ and 70% relative humidity or at $60^{\circ}C$ and 65% relative humidity. After this transformation occurs, the crystals can be made to undergo a reversible transformation into and out of the $L_{\alpha}$ phase. The x-ray-determined mosaic spread in the hydrated crystal is less than $\approx 0.04^{\circ}$ both above and below the main transition.Engineering and Applied Science

DETERMINING AN EFFECTIVE STRETCHING TIME FOR ACHILLES TENDON EXTENSION

Stretching exercises are commonly undertaken for sports and rehabilitation. However, it is unknown how an in vivo muscle-tendon unit responds to added stretching stimulation. The purpose of this study was to determine an effective stretching time for Achilles tendon extension. The human medial head of the gastrocnemius muscle was stretched and ultrasonography was used to determine and then compare the length of the Achilles tendon between before and after stretching. Achilles tendon extension for one minute of stretching was 3.4±2.5mm, two 6.8±2.1mm, three 6.9±1.0mm, five 7.2±0.7mm, and ten 7.4±0.8mm. Achilles tendon length was significantly increased for up to two minutes of stretching (

Relationship between reaction Time And Onset of The Muscle Activation During Drop Landing

Quickness is one of very important factors for athletes in sporting activities. Measuring reaction time reflects how quickly they can move by contracting associated muscles. Reaction time consists of the pre-motor time, as the time from stimulus input to the onset of the muscle activation, and the motor time, as the time from the onset of the muscle activation to the point of body motion begun. In 2004, Demont et al. were reported that a neuromuscular feed forward process as measured by preactivation of the muscle to stabilize joints dynamically during drop landing. This contributed to prevent injuries. Both time of pre-motor and preactivation were the muscle activities that occur before the body motion begins. The purpose of this study was to clarify the relationship between reaction time and onset of the muscle activity during drop landing

MUSCLE ACTIVITY IN THE SUBJECTS WITH FUNCTIONAL INSTABILITY OF THE ANKLE DURING A SINGLE-LEG DROP JUMP

Ankle sprain is one of the most common injuries experienced sporting participation, and Hertel J (2002) reported it’s recurrence rate is very high( 47-73 %). Presence of residual pain and functional problems (recurrent complaints of “giving way” or repeated sprain) following inversion ankle sprains are often reported. These symptoms of repeated complaints of “giving way” and/or recurrent sprains have been termed functional instability (FI) of the ankle joint with the report of Freeman, Dean and Hanham (1965). Including the report of Konradsen and Ravn (1991) and Hertsell and Spaulding (1999), There are many studies of muscle functions such as muscle strength, muscle activity, muscle response time of ankle joint evertor in the subjects with FI of the ankle joint. However, a few studies have researched muscle activity in the situation actually occurs ankle sprain such as jump landing on the subjects with FI of ankle joint. The purpose of this study was to identify differences in ankle joint muscle activity in subjects with FI of the ankle joint during a single-leg drop jump landing

RELATIONSHIP BETWEEN REDUCED OF MEDIAL LONGITUDINAL ARCH HEIGHT AND KNEE VALGUS

Knee valgus during jump landing is considered to be one of the situations that may cause injury to the anterior cruciate ligament (ACL). Decreased muscle torque during hip abduction is also reported to be a causative factor for knee valgus, as is pronation of the ankle joint (Joseph M et al. 2008). Further, knee valgus may occur when a reduction in the height of the medial longitudinal arch causes ankle pronation, leading to tibial inclination angle to the inside. In this study, motion analysis was performed to investigate the relationship between a reduction in the height of the medial longitudinal arch and knee valgus