Molecular Basis of Absorption at 340 nm of 3-Ketoglucosides under Alkaline Conditions.

Transient absorption at 340 nm under alkaline conditions has long been used to detect the presence of 3-keto-O-glycosides without understanding the molecular basis of the absorbance. The time course of A340 nm for the alkaline treatment of 3-ketolevoglucosan, an intramolecular 3-keto-O-glycoside, was investigated to identify the three products generated through alkaline treatment. By comparing the spectra of these compounds under neutral and alkaline conditions, we identified 1,5-anhydro-D-erythro-hex-1-en-3-ulose (2-hydroxy-3-keto-D-glucal) as being the compound responsible for the absorption.

Estimation of Vertical Ground Reaction Force during Single-leg Landing Using Two-dimensional Video Images and Pose Estimation Artificial Intelligence.

OBJECTIVE: Assessment of the vertical ground reaction force (VGRF) during landing tasks is crucial for physical therapy in sports. The purpose of this study was to determine whether the VGRF during a single-leg landing can be estimated from a two-dimensional (2D) video image and pose estimation artificial intelligence (AI). METHODS: Eighteen healthy male participants (age: 23.0 ± 1.6 years) performed a single-leg landing task from a 30-cm height. The VGRF was measured using a force plate and estimated using center of mass (COM) position data from a 2D video image with pose estimation AI (2D-AI) and three-dimensional optical motion capture (3D-Mocap). The measured and estimated peak VGRFs were compared using a paired t-test and Pearson's correlation coefficient. The absolute errors of the peak VGRF were also compared between the two estimations. RESULTS: No significant difference in the peak VGRF was found between the force plate measured VGRF and the 2D-AI or 3D-Mocap estimated VGRF (force plate: 3.37 ± 0.42 body weight [BW], 2D-AI: 3.32 ± 0.42 BW, 3D-Mocap: 3.50 ± 0.42 BW). There was no significant difference in the absolute error of the peak VGRF between the 2D-AI and 3D-Mocap estimations (2D-AI: 0.20 ± 0.16 BW, 3D-Mocap: 0.13 ± 0.09 BW, P = 0.163). The measured peak VGRF was significantly correlated with the estimated peak by 2D-AI (R = 0.835, P <0.001). CONCLUSION: The results of this study indicate that peak VGRF estimation using 2D video images and pose estimation AI is useful for the clinical assessment of single-leg landing.