Mechanical grinder

It is essential that the sodamide be very finely divided. The state of subdivision of the sodamide particles seriously affects the yield of product. A mechanical grinder was used by the original authors who obtained better yields than those reported here. 

Before many of the techniques for processing solid samples can be employed, the solid sample must be homogenized. There are many physical techniques to accomplish this goal. First, grinding, such as with a mortar and pestle or with a mechanical grinder puts the sample into a... 

Kava preparation today in bars on Pohnpei, and also in Port Vila s nakamals — which feature green kava - relies on various sorts of mechanical grinders, some hand-cranked... 

Other methods that are used less frequently include diffuse reflectance and photacoustic spectroscopy. These are treated in detail elsewhere in this encyclopedia and each have their own sampling problems. In favorable cases it is possible that no sample preparation is required more often, better results are obtained if the sample is ground to a fine powder. This often requires a mechanical grinder, sometimes at liquid nitrogen temperature. 

The sample is ground to a submicrometer particle size (less than 0.1 tm) in either a pestle and mortar (preferably made from agate) or a mechanized grinder. 

The mycelium is frozen at least one night at -20°C before grinding with mechanical grinder in buffer (TRIS-HCl 100 mM, pH 8.0 sucrose 00 mM, Na EDTA 1 mM, cystein chloride mM, 2-mercaptoethanol 8 mM). From this step all operations are done at + °C.The extract is filtrated through tissue and centrifuged 20 minutes at 9000xg. 

In general, the physical structure of the tissue must be broken down mechanically followed by an extraction procedure, before the sample can be analyzed. Homogenization using blenders, probe homogenizers, cell disrupters, sonicators, or pestle grinders is particularly useful for muscle, liver, and kidney samples. Regardless of the method used for tissue disruption, the pulse, volume of extraction solvent added, and temperature should be validated and standardized in order to ensure reproducible analytical results. During cell disruption, care should be taken to avoid heat build-up in the sample, because the analyte may be heat labile. 

Alternative terms for size reduction to describe the operations that subdivide solids mechanically are crushing and grinding. An ideal crusher or grinder should (i) have a large capacity (ii) require a small power input per unit of the product and (iii) yield a product of the size and/or the size distribution desired. 

Both rockets and projectiles are reverse-assembled (or accessed) to allow the agent to drain away and to be weighed and processed separately from the energetics. Bursters and fuzes, but not the rocket propellant, are separated from the munitions and sent to COINS. Bursters are sheared prior to introduction into the COINS bath. Upon removal from the rocket, propellant is fed into a grinder, where it is mechanically size-... 

Spiegelhalder, B., Muller, J., Drasche, H. Preussmann, R. (1987) V-nitrosodiethanolamine excretion in metal grinders. In Bartsch, H., O Neill, I.K. Schulte-Hermaim, R., eds. The Relevance of N-Nitroso Compounds to Human Cancer Exposures and Mechanisms (lARC Scientific Publications No. 84), Lyon, lARCPrei i, pp. 550-552 Sterzel, W. Eisenbrand, G. (1986) V-nitrosodiethanolamine is activated in the rat to an ultimate genotoxic metabolite by sulfotransferase. J. Cancer Res. din.Oncol., Ill, 20-24 Sullivan, P.A., Eisen, E.A., Woskie, S.R., Kriebel, D., Wegman, D.H., Hallock, M.F., Hammond, S.K., Tolbert, P.E., Smith, T.J. Monson, R.R. (1998) Mortality studies of metalworking fluid exposure in the automobile industry Vt. A case-control study of esophageal cancer. Am. J. ind. Med., 34, 36 8... 

Comminution, or particle size reduction of solids, is considerably different from that of the breakup of one liquid by dispersal as small droplets in another. Particle size reduction is generally achieved by one of four mechanisms (1) compression, (2) impact, (3) attrition and (4) cutting or shear. Equipment for particle size reduction or milling includes crushers (which operate by compression, e.g., crushing rolls), grinders (which operate principally by impact and attrition, although some compression may be involved, e.g.,... 

Mechanical Processes Stone groundwood SGW None Grinder 93-95... 

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