Dry weights

There is a close relationship between dry weight and microbial numbers. Although this method would give a good measurement of micro-organisms, there are serious problems in separating the micro-organisms from the sample, and the preparation time of samples is excessive. 

---

A rather more specific mechanism of microbial immobilization of metal ions is represented by the accumulation of uranium as an extracellular precipitate of hydrogen uranyl phosphate by a Citrobacter species (83). Staggering amounts of uranium can be precipitated more than 900% of the bacterial dry weight Recent work has shown that even elements that do not readily form insoluble phosphates, such as nickel and neptunium, may be incorporated into the uranyl phosphate crystallites (84). The precipitation is driven by the production of phosphate ions at the cell surface by an external phosphatase. 

Lycorine (69) was recognized as a potent emetic and a moderately toxic base from the time of its initial isolation from Narcissus pseudonarcissus E. (in about 1877) (48). Since that time its isolation from many other AmaryUidaceae, for example, Lpcom radiate Herb., has served to estabUsh it as the most cosmopohtan alkaloid of the family. TypicaUy, as much as 1% of the dry weight of daffodil bulbs may consist of lycorine (69), which has been reported to... 

Pectin. Pectin [9000-69-5] is a generic term for a group of polysaccharides, mainly partially methoxylated polygalacturonic acids, which are located in the cell walls of all plant tissues. The main commercial sources of pectin are citms peel and apple pomace, where it represents 20—40% and 10—20% of the dry weight respectively. The pectin is extracted, the extract purified, and the pectin precipitated (50) increased extraction times lead to the production of low methoxyl pectins. 

It was known as early as the 1920s that the pituitary gland contained a factor that could promote growth, but not until 1956 (1) was the factor isolated. hGH is extremely abundant in the pituitary, representing as much as 10% of this gland s dry weight, or 8 mg of hormone per gland (2). 

Waterborne contact adhesives contain an elastomer in latex form, usually an acryflc or neoprene-based latex, and a heat-reactive, cross-linkable phenohc resin in the form of an aqueous dispersion. The phenoHc resin improves metal adhesion, green strength, and peel strength at elevated temperature. A typical formulation contains three parts latex and one part phenohc dispersion (dry weight bases). Although metal oxides may be added, reaction of the oxide with the phenohc resin does not occur readily. 

Insoluble Matter. Insoluble matter in sugar is deterrnined as the dry weight of material left on a filter or membrane after passage of a sugar solution. This may include bits of sand, filtration medium, plant material, and polymeric material. 

As vitamin Bg is mainly located in the germ and aleurone layer in cereal grains polishing for the production of flour removes a substantial portion. White bread is therefore a poor source unless fortified. Some nonedible yeasts contain up to 38 mg/100 g dry weight vitamin B, the highest level of the natural sources (4,27). As a rule, these amounts are too low for cost-effective isolation. 

The amount of sludge produced duriag clarification can be reduced by 50—90% the approximate dry weights of soHds removed per pound of dry alum and ferric sulfate are approximately 0.11 and 0.23 kg, respectively. 

A very important parameter ia routine control of the process is the ratio of the MLSS volume to the dry weight, called the Sludge Volume Index (SVI). A weU operating plant has an SVI of 50 to 100, but operational difficulties occur when the SVI approaches 150. At this poiat the sludge settles poorly. 

---