Abstract: One object of the present invention is to provide a method or apparatus for purifying target particles from high-concentration particles in a short time. The above problem can be solved by a method for purifying target particles, characterized in that the method comprises a step of sorting the target particles from a high concentration of non-target particles, wherein the sorting step is repeated for three times or more.

Abstract: A roller ski board similar to an ordinary snow ski board having a board body with bending elasticity and repellant property, and having at least one of single roller at its central portion and with or without smaller twin rollers at its front and rear edge portions, pivoted rotatively on an under surface of the board body along its longitudinal axis. The rollers have a lubricity and wear proof property with repellant elasticity so as to absorb the vibrations and shock added to the board from or to the ground during sliding. The rollers are arranged such that each external side periphery of the rollers is gradually wider from the central portion to a front and rear edge so that the external side peripheries of each roller does not protrude over the contour curvature of the board body. The rollers are also arranged consecutively from both the front and rear edges to the central portion such that each running surface of the rollers contacts with an arc curvature slightly curved upwardly over the ground.

Abstract: A roller ski board similar to an ordinary snow ski board having a board body with bending elasticity and repellent property, and having at least one of single roller at it's central portion and with or without smaller two twin rollers at it's front and rear edge portions, pivoted rotatively on an under surface of the board body along it's longitudinal axis. The all rollers have a lubricity and a wear proof property with repellent elasticity so as to absorb the vibrations and shock added to the board from or to the ground during sliding. The all rollers are arranged such that each external side periphery of the rollers is gradually wider from the central portion to a front and rear edge so that the external side peripheries of each roller does not protrude over the contour curvature of the board body.

Abstract: A roller ski board similar to an ordinary snow ski board having a board body with bending elasticity and repellent property and a plurality of roller pairs pivoted rotatively on an under-surface of the board body along its longitudinal axis. The roller pairs have a lubricity and a wear proof property with repellent elasticity so as to absorb the vibrations and shock added to the board from or to the ground during sliding. The plurality of roller pairs are arranged such that the distance between the internal side peripheries of each roller pair is identical and between the external side peripheries is gradually wider from the central portion to a front and rear edge so that the external side peripheries of each roller pair does not protrude over the contour curvature of the board body. The roller pairs are also arranged consecutively from both the front and rear edges to the central portion such that each running surface of the rollers contacts with an arc curvature slightly curved upwardly over the ground.

Abstract: A flexible ski boot includes a divided rigid sole and a flexible hard boot body, the sole being divided into a rigid thick toe portion and a rigid thick heel portion. The boot body is composed of a hard toe portion, a soft flexible connecting portion and a hard heel portion which is, respectively, united or joined with the divided rigid sole. The divided rigid sole is connected, respectively, through a hinge between the toe portion and the heel portion so that the rigid ski boot can be bent at the soft elastic portion of the boot body for easier walking. The toe portion of the sole includes inwardly an elastic locking mechanism to lock elastically the hinge between the heel portion and permits the sole to be maintained evenly and to hold a suitable slouch during a descent, when the flexible ski boot is set into a binding, for safe skiing. The rear end of the sole is cut out diagonally as an additional aid for easier walking.

Abstract: A grass ski is designed to simulate a snow ski in skiing characteristics. The grass ski has an elongate footboard with forward, central and rear portions. The central portion is arched lengthwise in elevation. Suspended beneath the footboard are spaced pairs of rollers including at least one roller pair on the forward portion, at least three roller pairs on the central portion and at least one roller pair on the rear section. One of the roller pairs is mounted on a resilient T-shaped bracket. There are elevated side guards on the forward section.

Abstract: A grass ski is designed to simulate a snow ski in skiing characteristics. The grass ski has an elongate foot board with forward, central and rear portions. The central portion is arched lengthwise in elevation. Suspended beneath the foot board are spaced pairs of rollers including at least one roller pair on the forward portion, at least three roller pairs on the central portion and at least one roller pair on the rear portion. Each roller has a profile which reduces in diameter towards the outside. Preferably, the left and right hand rollers in plain view are located on concave lines lengthwise of the footboard.