Foaminess

Meihylamine hydrochloride method. Place 100 g. of 24 per cent, methyl-amine solution (6) in a tared 500 ml. flask and add concentrated hydrochloric acid (about 78 ml.) until the solution is acid to methyl red. Add water to bring the total weight to 250 g., then introduce lSO g. of urea, and boil the solution gently under reflux for two and three-quarter hours, and then vigorously for 15 minutes. Cool the solution to room temperature, dissolve 55 g. of 95 per cent, sodium nitrite in it, and cool to 0°. Prepare a mixture of 300 g. of crushed ice and 50 g. of concentrated sulphuric acid in a 1500 ml. beaker surrounded by a bath of ice and salt, and add the cold methylurea - nitrite solution slowly and with mechanical stirring and at such a rate (about 1 hour) that the temperature does not rise above 0°. It is recommended that the stem of the funnel containii the methylurea - nitrite solution dip below the surface of the acid solution. The nitrosomethylurea rises to the surface as a crystalline foamy precipitate. Filter at once at the pump, and drain well. Stir the crystals into a paste with about 50 ml. of cold water, suck as dry as possible, and dry in a vacuum desiccator to constant weight. The yield is 55 g. (5). 

There are many laboratory methods for testing the relative merits of one defoamer against another. It is a simple matter to measure foam height as a function of time to compare the performance of various foam surfactants and defoamers. Unfortunately, this simplicity has led to a wide variety of methods and conditions used with no standard procedure that would make the measurement of foaminess as characteristic of a solution as its surface tension or viscosity. It has been suggested that the time an average bubble remains entrapped ia the foam is such a quantity (49), but very few workers ia the defoamer iadustry have adopted this proposal. Ia practice, a wide variety of methods are used that geaerally fall iato oae of five maia categories ... 

The total volume must be sufficient to hold the estimated amount of liquid carryover from the reactor. For a foamy discharge. 

When liquid content of the feed is high, a condenser and a separator are needed. The liquid-to-gas ratio can be as high, so that even at reaction temperatures a liquid phase is present. The reactor still performs as a CSTR, however the response time for changes will be much longer than for vapor phase alone. Much lower RPM will be needed for liquid-phase studies (or liquid and gas phase experiments) since the density of the pumped fluid is an order-of-magnitude greater than for vapor phase alone. In this case a foamy mixture or a liquid saturated with gas is recirculated. 

Just inside the shell of the tube bundle is a cylindrical baffle F that extends nearly to the top of the heating element. The steam rises between this baffle and the wall of the healing element and then flows downward around the tubes. This displaces non-condensed gases to the bottom, where they are removed at G. Condensate is removed from the bottom of the heating element at H. This evaporator is especially suited for foamy liquids, for viscous liquids, and for those liquids which tend to deposit scale or crystals on the heating surfaces. Vessel J is a salt separator. 

The reaetion—vapor, gassy, or hybrid Flow regime—foamy or nonfoamy... 

The apparatus employed in the preceding experiment is used. To 600 g of 98% sulfuric acid at O " (ice-salt bath) is added about 3 ml of 88 % formic acid. When the rapidly stirred solution becomes foamy with evolution of carbon monoxide, 50 g of decahydro-2-naphthol and 100 g of 88% formic acid are added from two dropping funnels over 3 hours. During the addition, the temperature is kept below 5° the mixture continues to foam. Work-up as for the cis acid gives about 85% of solid acid, predominantly trans. After three recrystallizations from acetone, about 7 g of the pure acid is obtained, mp 135-136°. 

A mixture of 32 g of p-(aA, y.Tf f amethylbutyl)phenoxyethoxyethyl<)imethylamine and 12.7 parts of benzyl chloride was warmed in 50 g of benzene for 2 hours. The benzene was then evaporated. The residual viscous mass gave a foamy, soapy solution in water. 

Cells in the atheroma derived from both macrophages and smooth muscle cells that have accumulated modified low-density lipoproteins. Their cytoplasm laden with lipid causes the foamy appearance on microscopy... 

Propylene glycol alginate is stable in acids. It is used to preserve the foamy head on beers. 

It is used as a thickener in flans, custards, and puddings. It helps to keep whipped toppings foamy, and it thickens diet shakes and instant breakfast drinks. 

The first soaps were probably the saps of plants such as Chloro-galum pomeridianum, the roots of which can be crushed in water to form a lather. Other plants, such as soapbark (Quillaja saponaria), soapberry (Sapindus mukorossi), and soapwort (Saponaria officinalis) also contain the same main ingredient, a compound called saponin, which forms the foamy lather. 

Park J, Nadeau P, Zucah JR, Johnson CM, Mergia A (2005) Inhibition of simian immunodeficiency virus by foamy virus vectors expressing siRNAs. Virology 343 275-282... 

F (swollen adrenal cells with foamy cytoplasm and eccentric nuclei)... 

The adrenals of rabbits given a single dermal dose of 100 mg/kg of endosulfan exhibited microscopic changes, including swollen cells with foamy cytoplasm and eccentric nuclei (Gupta and Chandra 1975). Also, release of lipids from the adrenal cortex was observed in rats that died following daily application... 

Secondly, a stable icing foam requires a low surface tension. Consider the case of egg whites in a beater. With slight whipping, entrapped air bubbles are large and the whites appear foamy, yet transparent and runny. With longer whipping the whites become less transparent, white, and more solid. Thus, because of the low surface tension inherent in the egg protein in solution, more and more air may be incorporated and held in place by the colloidal protein which forms a film around each air cell. 

For example, a synergistic defoaming occurs when hydrophobic solid particles are used in conjunction with a liquid that is insoluble in the foamy solution [652]. Mechanisms for film rupture by either the solid or the liquid alone have been elucidated, along with explanations for the poor effectiveness, which are observed with many foam systems for these single-component defoamers. 

In atherosclerosis, ox-LDL is taken up ultimately by macrophages and smooth muscle cells in the arterial intima. Once loaded with lipid, these cells have a foamy appearance when examined histologically. The accumulation of these so-called foam cells in the artery wall leads to the formation of fatty streaks , which can lead to atheromatous plaque formation and consequent coronary heart disease. 

---