Abstract: A method for preparing a barium-ferrite-coated, needle-shaped .gamma.-Fe.sub.2 O.sub.3 magnetic powder of better properties is provided. The method includes the following steps of a) letting an iron-containing solution undergo a reaction to precipitate a needle-shaped .alpha.-FeOOH phase powder, b) mixing said .alpha.-FeOOH powder into a barium-containing solution in a predetermined Fe/Ba ratio, c) filtering without washing the precipitated powder, and d) subjecting the precipitated powder to heat treatments including calcination, reduction and oxidation.

Abstract: A method for preparing a magnetic recording medium includes the steps of providing a substrate, providing an alloy composite target attaching thereon Co and Fe pellets to modify the composition of this magnetic recording medium, and utilizing the target to form a (Co,Mn) modified .gamma.-Fe.sub.2 O.sub.3 thin film on the substrate under controlled conditions. Such method can provide a magnetic recording medium which is cost-effective and has a better SNR, a better resistance to corrosion and a high coercivity.

Abstract: An automatic monitoring and recording device for erythrocyte sedimentation employs a light source and a photodetector to detect the changes of light transmittance at the junction of plasma and red blood cell column. Changes of light transmittance at the junction reflect the descent of red blood cell column. The light source and photodetector pair is arranged so that it will track to the plasma - red blood cell column junction all the way the red blood cells fall. The whole course of erythroctye sedimentation is monitored and recorded automatically by a microcomputer.