Back stop

Move the back-stop out of the way. This is done using the remote control unit next to the instrument. 

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The back gauge is manually or power operated, or a combination of both, and is mounted from behind the blades. The basic components of the back gauge include a back stop, which provides the gauging surface, and precision screws and slides for positioning the back stop. 

Powered back gauges are front operated through the use of push buttons and are accurately positioned to the off-cut length to within 0.001 in. or better. Fine adjustments are dialed in manually. The back-stop gauging surface may be furnished with electronic probes that initiate the stroke only when the material is accurately in position to be sheared. 

Laclang quantified riskS national governments may step in as a back-stop to limit the liability of nanotechnology industries. 

A back end program essentially acts as a computational server for the front end. It receivcsinpiit, computes something, sendsit back to the front end and then looks for further input or commands from the front end. It can be used over and over for different cal-cii lation s. If it has been explicitly stopped, the Iron t end will start... 

An alternative method for ascertaining the end of the reaction, which does not involve the removal of the cover, is to conduct the exit gas through an empty wash bottle (to eict as a trap in case of sucking back ) and then collect a sample in a test-tube over water. If an inflammable gas (hydrogen) is absent, the reaction may be considered complete. Under no circumstances should the reaction be stopped until all the sodium has completely reacted too early arrest of the reaction may result in the product containing sodium hydride, which appears to be partially responsible for the explosive properties of the impure substance ... 

In a 250 ml. conical flask, fitted with an air condenser of wide bore, place 50 g. (51 -5 ml.) of acetonylacetone (see Section V,9, Note 2) and 100 g. of ammonium carbonate (lump form). Heat the mixture in an oil bath at 100° until effervescence stops (60-90 minutes) some ammonium carbonate (or carbamate) sublimes into the condenser and this must be pushed back into the reaction mixture by means of a stout glass rod. Replace the air condenser by a Liebig s condenser with wide bore inner tube and reflux the mixture gently (bath temperature, 115°) for a further 30 minutes dissolve the solid which has sublimed into the condenser in about 5 ml. of hot water and return the solution to the reaction mixture. 

After 5 hours the reaction is stopped and the flask cooled. The formyl-MDA can be isolated and hydrolyzed by any of the ways Strike just mentioned a few paragraphs back, but this method offers a third, very convenient way which should be tried. What the chemist does is forget about letting the flask and its contents cool. Instead, she removes the oil bath, places the flask back on the stirplate (distillation setup still attached), attaches a vacuum and distills off all the formamide. What remains is a dark, heavy formyl-MDA precipitate that is allowed to cool down while the chemist makes up a solution of 150g potassium hydroxide (KOH), 500mL ethanol and 125mL dH20. This solution is poured into the... 

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