First and second racks each has fixed positions to hold sample tubes. The glide foot also adjustably adds weight to the furniture to stabilize the furniture in windy conditions without detracting from the aesthetic appearance of the furniture. The resulting dispersion can in particular be used for preparing anti-UV filters, in catalysis, or as reinforcement of polymeric or mineral matrices. The media are characterized by the ability to promote and retain microbial growth. The magnets comprise magnets having external S poles and magnets having external N poles, and the magnets having external S poles and magnets having external N poles are arranged alternatively in an array.