Analysis of Biomechanical Parameters of Martial Arts Routine Athletes' Jumping Difficulty Based on Image Recognition.

This paper uses image segmentation technology to examine the biomechanical parameters of martial arts routine athletes' whirlwind legs and backflips, two difficult jumping sports. The successful completion of the whirlwind leg, a typical martial arts jumping difficulty, during the buffer period of the take-off stage, the left knee angle flexion, the drop of the body's center of gravity, and the drop of the horizontal speed of the center of gravity are all significantly correlated, so it is only necessary to grasp airborne altitude and speed from landing. The 720-degree cyclone foot has a flying height of 0.470.11 m, which is 4 cm higher than the 540-degree cyclone foot (0.430.11 m). The antigravity of the last foot is greater than about 1.3 kgf/kg of the left foot during the run-up stage, which allows for a higher rotational angular velocity and completion of the 720-degree difficulty of the whirlwind foot. As a result, it is crucial to pay attention to how you step with your right foot. In the backflip, the coordination of the two legs and the upper body is crucial. The right foot's effective braking can help to increase the body's rising angle. The trunk inclination angle in the flying stage is between 110° and 120°, the knee angle is between 60° and 70°, and the angle between the two legs is between 35° and 35°. When lifting off the ground and landing, the tibialis anterior muscle discharge is greater than the gastrocnemius muscle discharge, which helps to maintain the balance between the fulcrums. As a result, it is necessary to let the non-supporting leg fall first in order to achieve the goal of a smooth landing.

Electrochemical DNA Biosensor Based on a Tetrahedral Nanostructure Probe for the Detection of Avian Influenza A (H7N9) Virus.

A DNA tetrahedral nanostructure-based electrochemical biosensor was developed to detect avian influenza A (H7N9) virus through recognizing a fragment of the hemagglutinin gene sequence. The DNA tetrahedral probe was immobilized onto a gold electrode surface based on self-assembly between three thiolated nucleotide sequences and a longer nucleotide sequence containing complementary DNA to hybridize with the target single-stranded (ss)DNA. The captured target sequence was hybridized with a biotinylated-ssDNA oligonucleotide as a detection probe, and then avidin-horseradish peroxidase was introduced to produce an amperometric signal through the interaction with 3,3',5,5'-tetramethylbenzidine substrate. The target ssDNA was obtained by asymmetric polymerase chain reaction (PCR) of the cDNA template, reversely transcribed from the viral lysate of influenza A (H7N9) virus in throat swabs. The results showed that this electrochemical biosensor could specifically recognize the target DNA fragment of influenza A (H7N9) virus from other types of influenza viruses, such as influenza A (H1N1) and (H3N2) viruses, and even from single-base mismatches of oligonucleotides. Its detection limit could reach a magnitude of 100 fM for target nucleotide sequences. Moreover, the cycle number of the asymmetric PCR could be reduced below three with the electrochemical biosensor still distinguishing the target sequence from the negative control. To the best of our knowledge, this is the first report of the detection of target DNA from clinical samples using a tetrahedral DNA probe functionalized electrochemical biosensor. It displays that the DNA tetrahedra has a great potential application as a probe of the electrochemical biosensor to detect avian influenza A (H7N9) virus and other pathogens at the gene level, which will potentially aid the prevention and control of the disease caused by such pathogens.