Molecular weight starch

This case is typical of many others. In six patients with cerebral circulatory disturbances who received hemodilution therapy for 9-10 days with etherified starches (molecular weight 200 kDa and a high degree of substitution, 0.62), all the multimers of von Willebrand factor fell to the same extent. This corresponds to type 1 von... 

In the second part, the main results obtained in the domain of starch characterization were recalled showing the necessity to adopt a multidetection system for the analysis of starch molecular weight distribution. Nevertheless, the major problem remains the preparation of a good solution avoiding aggregates and with no adsorption on the gel matrix. 

One commercially available ultrafiltration membrane is claimed to have a permeability of 0.62 m /m day under a pressure difference of 3.4 atm. This membrane initially rejects 96% of a 3 wt% suspension of partially hydrolyzed starch (molecular weight 17,000). However, if 4.2 cm of membrane separates 65 cm of a starch solution from the same volume of pure water, the volumetric flow is zero, and the osmotic difference is 85% of the original value in one week. Assuming the temperature is 25 °C, find the permeability ip, the solute permeabilty m, and the reflection coefficient [Pg.547]

Ghdants are needed to faciUtate the flow of granulation from the hopper. Lubricants ensure the release of the compressed mass from the punch surfaces and the release/ejection of the tablet from the die. Combinations of siUcas, com starch, talc (qv), magnesium stearate, and high molecular weight poly(ethylene glycols) are used. Most lubricants are hydrophobic and may slow down disintegration and dmg dissolution. 

Com symps [8029-43 ] (glucose symp, starch symp) are concentrated solutions of partially hydrolyzed starch containing dextrose, maltose, and higher molecular weight saccharides. In the United States, com symps are produced from com starch by acid and enzyme processes. Other starch sources such as wheat, rice, potato, and tapioca are used elsewhere depending on avadabiHty. Symps are generally sold in the form of viscous Hquid products and vary in physical properties, eg, viscosity, humectancy, hygroscopicity, sweetness, and fermentabiHty. 

PuUy hydroly2ed poly(vinyl alcohol) and iodine form a complex that exhibits a characteristic blue color similar to that formed by iodine and starch (171—173). The color of the complex can be enhanced by the addition of boric acid to the solution consisting of iodine and potassium iodide. This affords a good calorimetric method for the deterrnination of poly(vinyl alcohol). Color intensity of the complex is effected by molecular weight, degree of... 

Since polysaccharides are the most abundant of the carbohydrates, it is not surprising that they comprise the greatest part of industrial utiliza tion (9,22). Most of the low molecular weight carbohydrates of commerce are produced by depolymerization of starch. Polysaccharide materials of commerce can be thought of as falling into three classes cellulose, a water-insoluble material starches, which are not water-soluble until cooked and water-soluble gums. 

Poly(vinyl acetate) is too soft and shows excessive cold flow for use in moulded plastics. This is no doubt associated with the fact that the glass transition temperature of 28°C is little above the usual ambient temperatures and in fact in many places at various times the glass temperature may be the lower. It has a density of 1.19 g/cm and a refractive index of 1.47. Commercial polymers are atactic and, since they do not crystallise, transparent (if free from emulsifier). They are successfully used in emulsion paints, as adhesives for textiles, paper and wood, as a sizing material and as a permanent starch . A number of grades are supplied by manufacturers which differ in molecular weight and in the nature of comonomers (e.g. vinyl maleate) which are commonly used (see Section 14.4.4)... 

Coagulation involves the addition of chemicals to alter the physical state of dissolved and suspended solids. This facilitates their removal by sedimentation and filtration. The most common primary coagulants are alum ferric sulfate and ferric chloride. Additional chemicals that may be added to enhance coagulation include activate silica, a complex silicate made from sodium silicate, and charged organic molecules called polyelectrolytes, which include large-molecular-weight polyacrylamides, dimethyl-diallylammonium chloride, polyamines, and starch. 

Starch is a mixture of glucose polymers, some of which are water-soluble. This soluble portion consists of comparatively short chains (molecular weight 4000). The portion of low solubility involves much longer chains and the polymer chain is branched. 

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