Activity of knee extensor muscles evaluated by Electromyography and MC sensor method

J-GLOBAL ID : 201401079533207271J-GLOBAL ID : 202001020973622576J-GLOBAL ID : 202101011515064120J-GLOBAL ID : 201901011536506168J-GLOBAL ID : 201801000910828540J-GLOBAL ID : 201701005445265627In this study, the characteristics of the muscle activity on knee extensor muscles and the interaction under the decrease of knee extension torque caused by a continuous knee extension and flexion task were evaluated by electromyography and MC sensor methods (MC). The subjects were 18 healthy males. The continuous task on 30 times knee extension isokinetic contraction was performed by dynamometer (Biodex). And measurement of maximal torque on isometric contraction was pre and post continuous task. At the same time, the muscle activity and deformation amount at the vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles were measured using the surface electromyography and MC sensor method (TMG. BMC). As a result, the continuous knee extension task reduced knee extension torque by 10％. In addition, the muscle activity at the VMO and VL higher in post than pre during the continuous knee extension task. However, the deformation amount was lower in post than in pre during the high-intensity (over the 30％MVC) torque exertion. Moreover, the significant correlations were observed between the relative values of VMO and VL muscle activity and deformation amount pre and post the continuous knee extension task, respectively. Therefore, although the evaluation methods were different, coordinated muscle activity and deformation amount between VMO and VL were confirmed.22K115821520578603916839936application/pdfdepartmental bulletin pape

Effect of surface design on drag properties of soccer balls

The paper describes the critical Reynolds number of soccer balls as a function of the total groove volume on the ball surface. In this study, the aerodynamic drag and separation point of 6 soccer balls with different panel orientations were measured in a wind tunnel. Moreover, the total volume of grooves on the ball’s surface was measured by One shot 3D measuring machine. It was found that the drag coefficient in the supercritical region and the critical Reynolds number depend on the design of the ball surface (shape, number of panels, surface roughness). A negative correlation exists between the total groove volume on the surface and the critical Reynolds number. When the total groove volume is large, the drag in the supercritical region increases. The position of the separation point does not change in the subcritical and supercritical regions even if the orientation of the panel is changed. However, when the groove width is wider, the panel orientation dependence becomes significant in the supercritical region. In the transition region, the position of the separation point differs depending on the panel's orientation

UV Sterilization Effects and Osteoblast Proliferation on Amorphous Carbon Films Classified Based on Optical Constants

Optical classification methods that distinguish amorphous carbon films into six types based on refractive index and extinction coefficient have garnered increasing attention. In this study, five types of amorphous carbon films were prepared on Si substrates using different plasma processes, including physical and chemical vapor deposition. The refractive index and extinction coefficient of the amorphous carbon films were measured using spectroscopic ellipsometry, and the samples were classified into five amorphous carbon types—amorphous, hydrogenated amorphous, tetrahedral amorphous, polymer-like, and graphite-like carbon—based on optical constants. Each amorphous carbon type was irradiated with 253.7 nm UV treatment; the structure and surface properties of each were investigated before and after UV treatment. No significant changes were observed in film structure nor surface oxidation after UV sterilization progressed at approximately the same level for all amorphous carbon types. Osteoblast proliferation associated with amorphous carbon types was evaluated in vitro. Graphite-like carbon, which has relatively high surface oxidation levels, was associated with higher osteoblast proliferation levels than the other carbon types. Our findings inform the selection of suitable amorphous carbon types based on optical constants for use in specific medical devices related to osteoblasts, such as artificial joints and dental implants

Dynamic formation of a microchannel array enabling kinesin-driven microtubule transport between separate compartments on a chip

Microtubules driven by kinesin motors have been utilised as "molecular shuttles" in microfluidic environments with potential applications in autonomous nanoscale manipulations such as capturing, separating, and/or concentrating biomolecules. However, the conventional flow cell-based assay has difficulty in separating bound target molecules from free ones even with buffer flushing because molecular manipulations by molecular shuttles take place on a glass surface and molecular binding occurs stochastically; this makes it difficult to determine whether molecules are carried by molecular shuttles or by diffusion. To address this issue, we developed a microtubule-based transport system between two compartments connected by a single-micrometre-scale channel array that forms dynamically via pneumatic actuation of a polydimethylsiloxane membrane. The device comprises three layers - a control channel layer (top), a microfluidic channel layer (middle), and a channel array layer (bottom) - that enable selective injection of assay solutions into a target compartment and dynamic formation of the microchannel array. The pneumatic channel also serves as a nitrogen supply path to the assay area, which reduces photobleaching of fluorescently labelled microtubules and deactivation of kinesin by oxygen radicals. The channel array suppresses cross-contamination of molecules caused by diffusion or pressure-driven flow between compartments, facilitating unidirectional transport of molecular shuttles from one compartment to another. The method demonstrates, for the first time, efficient and unidirectional microtubule transport by eliminating diffusion of target molecules on a chip and thus may constitute one of the key aspects of motor-driven nanosystems