An aluminum head drum for use in a video cassette recorder is coated with a protective layer comprising diamond-like carbon. The protective layer of diamond-like carbon is obtained using a plasma-enhanced chemical vapor deposition method and has a thickness ranging from 0.3 .mu.m to 2.0 .mu.m. The protective layer has a varying mechanical hardness, wherein the mechanical hardness has a maximum value at a region of the protective layer coming in contact with the aluminum head drum, decreases smoothly and continuously and reaches an minimum value at a region of the protective layer coming in contact with atmosphere. Micro-Vicker's hardness of the region of the protective layers coming in contact with a video tape is 1.5-2.0 times that of the magnetic substance constituting the video tape.
An optical assay device for the detection of an analyte of interest in a sample comprising a support containing channels, an optically functional layer positioned on the support such that the optically functional layer and the support allow for laminar flow of the sample through layers of the device, an attachment layer positioned on the optically functional layer, and an analyte specific receptive layer positioned on the attachment layer.
An optical assay device for the detection of an analyte of interest in a sample comprising a support containing channels, an optically functional layer positioned on the support such that the optically functional layer and the support allow for laminar flow of the sample through layers of the device, an attachment layer positioned on the optically functional layer, and an analyte specific receptive layer positioned on the attachment layer.
