Glass-covered rolls

More recent developments in the rolling ball area include an automated micro viscometer, the Paar AMV 200, from Paar Physica. The specimen to be measured is introduced into a glass capillary down which a gold-covered steel ball roUs. The rolling time is measured automatically. The shear stress may be varied by changing the inclination angle of the capillary tube. The shear rate range is 10 1000, which makes the instmment useflil for... 

The cathode is a rolled strip of copper gauze which fits snugly into a 3 X in. test tube and rests on a glass-wool plug which covers a hole of about -in. diameter blown in the bottom of the test tube. During the preparation, the solution about half fills the tube, and the glass-wool plug protects the bulk of the oxidized solution from the cathode. 

The wear of the pins on the glass disk was observed with an optical microscope. The worn end of the pin was covered with material from the elastomeric domains. As the tests proceeded, the elastomer appeared to be rolled into thin cylinders oriented perpendicular to the sliding direction. 

Place three soaked sheets of filter paper on the anode, one on top of the other The sheets should be saturated, but not dripping with excess buffer. Place the sheet of wet membrane on top of the filter paper stack and cover with the gel. Roll a glass rod (or similar) over the surface of the gel to push out any air bubbles, and to ensure good contact between the gel and the membrane. Finally, place the three remaining sheets of soaked filter paper on top of the gel... 

Cellophane dosimeter strips from beneath the treated samples were then compared with the control piece from the same section of a roll. In all tests, there was clear evidence that penetration had occurred. At the higher energies, there was evidence of secondary effects—backscattering and possibly, secondary emission. The discoloration of the glass slides showing fairly sharp delineation between the uncovered and covered portions gave useful visual evidence of what had occurred. 

Dry the surface of the gel by placing several layers of tissue paper on top and rolling gently with a pipette. Carefully peel off the paper and invert the gel onto a piece of used X-ray film. Lift off the glass plate leaving the gel adhering to the film, cover with sarenwrap, place a film on top and autoradiograph at —20°C in a film cassette or under a heavy steel plate. 

The bottom frame is constructed so that the whole unit can be moved on the ground, for instance on grass or on rolling bars. The sampler does not necessarily need a concrete platform—the frame is so stiff that it will even stand on four rocks if necessary. The covers are of GRP, glass-reinforced plastics. They are thick enough to withstand even small flying stones. 

Prior to the invention of screw closures, corks, glass stoppers, pulpboard discs and parchment covers were the main closures. Historically, prethreaded screw closures have consisted of a threaded shell containing a wad or liner and a facing. The wad or liner may be made from cork agglomerate (gelatin or resin bonded), pulpboard, feltboard, plastic or rubber. It provides a resilient backing which receives the compression. In the case of screw closures the compression is due to the application of a controlled torque. Other closures, e.g. roll on, clinch, press on, may achieve this by the simple application of top pressure. Under the normally recommended torques, composition cork compresses by about 50% and pulpboard by approximately 20%. 

Make up some solvent mixture and put 25 ml into the 1 litre beaker. Roll the solvent round the walls and cover the clock glass. Put about 2 ml of... 

Roll Grow plating beads are cleaned using the same procedure for cleaning the cover glass. 

If true crystal thickness is required, the crystal may be rolled in refractive-index oil to the proper measurable position by tapping the cover glass with a pencil point while observing the particle motion. A high-viscosity liquid such as marine varnish (n = 1.63) facilitates the technique of crystal rolling and measurement. 

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