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Purpose The purpose of this manuscript was to investigate the effect of high and low speed blood flow restriction versus non-blood flow restriction isokinetic exercise on isometric muscle strength, muscle fatigue, and muscle contraction displacement. Methods The subjects were consisted of ten males without non-specific muscular skeletal disease. They were classified into four training groups: ① high speed(300°/s) without blood flow restriction, ② high speed(300°/s) under blood flow restriction, ③ low speed(90°/s) without blood flow restriction, ④ low speed(90°/s) under blood flow restriction. Before and after the intervention, all of the subjects underwent measurements of isometric quadriceps strength, muscle fatigue, and muscle contraction displacement. Results In regard to isometric quadriceps strength before & after intervention, there was no significant difference between groups. For the lactic acid measurement before & after intervention, there was a signigicant difference between groups(p

Aluminum powder particles were deposited on medium carbon steel substrate by cold spraying process. High resolution observation showed that the particles were severely deformed in solid state, whereas the substrate was hardly deformed. Furthermore, the particles were not bonded intimately to the substrate, and most of all, oxygen as well as thin gap were clearly detected along the interface of particle/substrate. Based on the observations, the impacting behavior of a particle on a substrate as well as the influence of the oxide film was modeled. The oxides covering the surface of metallic powder particles and the substrate significantly affect the impact and deformation behaviors of particle and substrate, and consequently the values of strain, stress, and temperature at the interface in the numerical simulation.

The paper describes a technique development using focused ion beam and transmission electron microscopy to find and analyze fine particles which acted as the heterogeneous nucleation substrate for aluminum grains. An aluminum alloy was melted, sheared intensively by a melt conditioning unit, and cast by a laboratory scale horizontal twin roll caster. The intensively sheared alloy showed low segregation of solute elements on the surface as well as at the centerline, probably by enhanced nucleation of aluminum grains from fine oxide particles. In order to verify the possibility of the heterogeneous nucleation of aluminum grains, several techniques using focused ion beam and transmission electron microscopy were tried to find any oxide particles in the grains. Finally, a technique using the lifting-out of a lamella combined with the serial milling by focused ion beam detected a fine particle at the center of one aluminum grain and transmission electron microscopy confirmed the particle as an oxide. The intense nucleation of aluminum grains on fine dispersed oxides in the intensively sheared aluminum alloy can induce uniform distribution of solute elements and consequently minimize the severe centerline and surface segregations.