In one embodiment, a snowboard stop device includes a bottom portion having a snowboard-contactable side and a ground-contactable side. The microcapsules, which may be applied to soil, seeds andor plants, each have a shell that encapsulates an agricultural chemical, such as a fertilizer, herbicide or insecticide. The concentration zone is defined in a segment between two or more electrodes seen in flow direction of the sample or sample fractions to be separated. The electric machine or device may be fluid-sealed andor fluid-cooled.