Usual mounting medium

Sections developed with permanent labeling methods (e.g., with DAB) can also be counterstained using, for instance, cresyl violet or aqueous toluidine blue to stain Nissl substance. For permanent stains, the usual mounting medium is one of low viscosity so it gives a thinner adhesive layer of appropriate optical properties (e.g., Permount ). For fluorescence, a corresponding typical fluorescence-free mounting medium is preferred (e.g., VECTASHIELD ). 

The choice of the mounting medium usually obviates the need for any new instmmental technique for enhancing contrast. A particle mounted in a... 

Polychlorinated Biphenyls. There are several sources of polychlorinated biphenyls (PCBs) in museums. Often these are first discovered by waste-disposal companies that pick up a museum s hazardous refuse. Disposal companies usually analyze solvent, paint, and other hydrocarbon wastes because disposal of PCB-contaminated material is vastly more complex and expensive than disposal of ordinary wastes. In some cases, museum waste has been contaminated by fluids leaking from transformers or fluorescent light ballasts, both of which are common sources of PCBs. However, on two occasions of which the present author is aware, the contamination was from Arochor slide-mounting medium (a material which contains PCBs and polychlorinated triphenyls) and/or PCB-contaminated pigments such as phthalocyanine blue and green, and diarylide (benzidine) yellow. 

Clove oil with a refractive index of 1.544 is commonly used as a mounting medium for mineral grains and has obvious advantages when dealing with quartz and feldspar, which usually predominate in fine sands. However, very few heavy minerals have a refractive index (RI) below that of clove oil, so that a medium with a higher refractive index such as a-mono-bromnaphthalene (RI 1.655) is preferable. 

Mounting mount sections in aqueous medium or balsam for brightfield microscopy or in anti-fade medium for fluorescence microscopy (see Sect. 3.2.2). Notes. A11 incubations are at room temperature unless otherwise noted. Nuclear dyes (DAPI, Hoechst 33342 and Propidium Iodide) supplied as lyophilized solids are usually reconstituted in methanol. The stock solutions (5 mg/ml) are stable for many years when stored frozen at <—20°C and... 

Microscreening is a method of filtration that uses fabric as the filtering medium. Microscreens (microstrainers) usually consist of a special metallic or plastic fabric mounted on the periphery of a revolving drum. The untreated water flows into the drum and radiates outward through the microfabric, leaving behind the suspended solids removed by the cloth. The solids retained on the inside of the rotating screen are carried upward to a row of backwash jets that flush them into a hopper, which is mounted on a hollow axle of the drum, for return to the treatment plant. 

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