Feathering method

The absorption rate constant is determined by a method known as "feathering," "method of residuals" or "curve stripping." The method allows the separation of the monoexponential constituents of a biexponential plot of plasma concentration against time. From the plasma concentration... 

The absorption rate constant and the absorption phase half life are obtained from the residual or feathering method. From the data in Fig. 6.20, the differences between the observed and the extrapolated plasma concentrations are calculated (Table 6.6, column 4) and are then plotted against time (column 1) on semilogarithmic paper. 

Cadmium and lead profiles in birds feathers based on samples in the milligram range and below were determined by solid sampling Zeeman-GFAAS, using a feather RM produced by milling at liquid nitrogen temperatures and characterized for its metal contents with different analytical methods (Hahn et al. 1990). 

Hahn E, Hahn K, Mohl C, Stoeppler M (1990) Zeeman SS-GFAAS - an ideal method for the evaluation of lead and cadmium profiles in bird s feathers. Fresenius J Anal Chem 377 306-309. 

This method of calculation is often referred to as the method of residuals or feathering the curve. It is important to remember that the following assumptions were made ... 

Z-Cystine has been obtained by the hydrolysis of a large number of proteins. However, the keratins are the only common proteins rich enough in cystine to serve as a source for this amino acid. Many investigators have devised methods for its isolation from the hydrolytic products of human hair,3 wool,2 horn,3 nail,3 feathers,3 and horse hair.4 The method of Folin5 is the basis for most of the others. The present method does not claim to give as high a yield as some of those reported in the literature, but is convenient and gives consistent results. 

R. L. Whistler and M. S. Feather, Carboxyl determinations. Uronic acid carboxyl and total carboxyl, Methods Carbohydr. Chem., 1 (1962) 464-468. 

Alopecia Areata Alopecia areata is a relatively common autoimmune skin disease that affects humans, mice, rats, horses, dogs, cattle, and even a feather form in chickens (26). Although the disease occurs spontaneously, mice have a low frequency of disease. Full thickness skin grafts provided a reproducible and predictable model (53). This mouse has been used effectively to test drugs known to work on humans with alopecia areata by all methods discussed in this chapter (27). 

Whistler, R. L., and Feather, M. S. (1965). Hemicellulose extraction from annual plants with alkaline solutions. Methods in Carbohydrate Chemistry, Vol. V, pp. 144-145. Academic Press, New York. 

The old commercial method of preparing the salt lay in heating nitrogenous material, such as horn, wool, feathers, blood, etc., with potash and iron turnings. The mass was ultimately heated to fusion to complete the reaction, cooled, and extracted with boiling water. The solution contained potassium ferrocyanide, thiocyanate, carbonate, and sulphide. The first-named was crystallised out, but the yield was seldom more than 20 per cent, of the quantity theoretically obtainable from the nitrogen content of the organic material consumed. 

Values for Leghorn feather obtained by the method of Leach (1960). 

Hydrolyzed Poultry Feathers is the product resulting from the treatment, under pressure, of clean, undecomposed feathers from slaughtered poultry, free of additives or accelerators. Not less than 75% of its crude protein content must be digestible by the pepsin digestibility method. 

Other methods of leak detection include using soap fluid with a little water in it, ultrasonic detectors, stethoscopes, feathers and electronic gas leak detectors. The reality of leak detection is that each method has its place, but each method is limited to certain leak characteristics. If one type of sensor does not show a leak, another may find it. 

A turkey feather, or any good-sized downy feather, is a good visual indicator for leaks, but they can be tricky to use because they are so sensitive that any breathing or very slight movement of air from any source can also ruffle the down. It s not exactly high tech, but I have found it to be a very effective method of leak detection. 

---