Abstract: A slide fastener slider comprises a pair of upper and lower wings joined integrally together at its front end by a diamond; and a pair of flanges disposed between the upper and lower wings and converged towards the rear end of the slider to thus define with the diamond a Y-shaped guide channel for running of fastener element rows therethrough. The slider further includes a plurality of large-diametered guide rollers rotatably mounted thereon for rolling engagement with the fastener element rows. The slider is specifically constructed such that there remain open spaces around the guide rollers, so that stringer tapes is quite immune from being stuck in the guide rollers.

Abstract: A flow rectifying device is provided in a cultivation basin used in the cultivation of algae of the type in which there is a horizontal circulating flow of the cultivation water. The flow rectifying device avoids the formation of puddles or stagnant water and provides for uniform flow of the circulating water as the direction of flow changes at corners of the basin. The flow rectifying means includes a plurality of curved parallel fins for smoothly deflecting the flow of the circulating cultivation water and thereby prevents contamination of the cultivation liquid by preventing algae from being destroyed. The apparatus is particularly useful in cultivating blue-green algae of the genus Spirulina and other aquatic lower algae.