Scientific apparatus and instruments, namely pH meters, temperature-measuring devices, dissolved oxygen instrumentation; magnetic stirrers for laboratory use, namely magnetic glass stirrers, stirring machines for use in biological research, stirring machines for use in pharmaceutical research, stirring machines for use in microbiological research; membranes for scientific apparatus, namely acoustic membranes, filter membranes, pressure membranes, diaphragms, tissue membranes; apparatus for sc...