Density gradient technique

ASTM-D 1505-85 Standard test method Density of plastics by the density-gradient technique ... 

W. Machtle, Analysis of polymer dispersions with an eight cell-AUC-multiplexer high resolution particle size distribution and density gradient techniques (in Ref. [77]). 

Cadmium acetate is used in the pottery and porcelain industry for producing iridescent effects the borotungstate forms an aqueous solution of high density when concentrated (d = 3.28), useful in die mechanical separation of minerals and in density gradient techniques the bromide, like the zinc salt, is used in photography, process engraving and lithography. 

The enzyme was originally found to be membrane bound and resisted solubilization and purification (26). Lundblad and Moore (27), however, have reported solubilizing it using dilute (5 mM) sodium borate buffer at pH 9 after 16 hr at 37°. Studies on regional and subcellular distribution using density gradient techniques have revealed that the 2, 3 -cyclic phosphate diesterase concentrates in those fractions containing myelin (28, 29), and the conclusion has been reached that the enzyme is localized in the myelin sheath or intimately associated structures. Kurihara and... 

Work is now underway to separate these various resinite types using density gradient techniques and to chemically characterize the separated resinite fractions. 

American Society for Testing Materials (ASTM) Standards, Part 9, (1961), Tentative Method D1505-60T, Density of Plastics by the Density Gradient Technique. ... 

DNA was extracted from the bacteria at various times after they were transferred from a N to a medium. Analysis of these samples by the density-gradient technique showed that there was a single band of DNA after one generation. The density of this band was precisely halfway between the densities of the " N DNA and N DNA bands (Figure 4.1 S). The absence of DNA indicated that parental DNA tuas not preserved as. 

ASTM D 1505 Standard Test Method for Density of Plastics by the Density-Gradient Technique ... 

Crystallization. We measured the density of initially amorphous PET films following exposures to methylene chloride at unit activity, thereby obtaining crystallization kinetics. The density gradient technique was used (18) with carbon tetrachloride/n-heptane mixtures as the immersion media. To avoid spurious readings, efforts were made to remove residual solvent from the crystallized samples and to prevent the entrapment of air in surface cavities during the density... 

ASTM DI505. Density of (solid) plastics by density gradient technique. 1985. 

Density-gradient separations of cytoplasmic fractions from liver have been carried out to study the distribution of activity of several enzymes (Thomson, 1959). Ribosomes and polysomes have been fractionated to elucidate the mechanisms of protein synthesis (Watson, 1964), Various viruses have been studied with the density-gradient technique polio virus (Levintow and Darnell, 1960), Rous sarcoma virus (Crawford, 1960), Shope papilloma virus (Williams et ai, 1960), and adenoviruses (Allison et ai, 1960). Density-gradient fractionation has been particularly useful for separation of DNA molecules from various species of bacteria (Rolfe and Meselson, 1959) and from animal cells (Kit, 1961), Other types of molecules, e.g., antibodies, lipoproteins, and rheumatoid factor have been isolated by density-gradient methods [see Charlwood (1966) for examples]. 

The chemical compositions of melanosoma and mitochondria have been determined and compared, using differential and density-gradient techniques 241). The data show that melanosomal fractions contain a high percentage of Zn and a low content of RNA and phospholipid-P as compared with mitochondrial fractions. The lack of succinoxidase and glutamate oxidase activities support the idea that melauosomes are sub-cellular particles, different from mitochondria, and contain a particular specialized metabolic pathway through which tyrosine or dopa is converted into melanin (259). 

Of the techniques mentioned, the density gradient technique is used in most electrofocusing experiments reported to date, although gel electro-focusing has recently had wide applications. Valmet s zone convection eUcirofocusing is a promising new approach to the stabilization problem. There also, no added stabilizing medium is necessary. 

The amplification of the ribosomal genes also has been demonstrated by hybridization and CsCl density gradient techniques. 

D792, specific gravity and density D1505, density by density-gradient technique Optical tests... 

D1505 Test method for density of plastics by density gradient techniques... 

Moving-boundary and density-gradient techniques are often designated as free electrophoresis methods to distinguish them from electrophoresis in porous and gel media. 

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