Stabilizing substances

Formulations. Any formulation is a compromise between the previously mentioned requirements. For example, the fermentation broth may contain enzyme-stabilizing substances, but the appHcation of the enzyme or precipitation problems in the formulation may demand a high degree of purification that eliminates the stabilizers. Alternatively, the pH necessary for good microbial or physical stabiHty may differ from the pH that gives optimum enzyme stabiHty, or a preservative that is effective at the optimum pH for enzyme stabiHty may have a denaturing effect on the enzyme. 

One useful method of aqueous defoaming is to add a nonfoam sta-bihzing surfac tant which is more surface-active than the stabilizing substance in the foam. Thus a foam stabilized with an ionic surfactant can be broken by the addition of a very surface-active but nonstabihzing sihcone oil. The sihcone displaces the foam stabilizer from the interface by virtue of its insolubility. However, it does not stabilize the foam because its foam films have poor elasticity and rupture easily. 

Stabilizers Substance which makes it possible to maintain the physicochemical state of a foodstuff stabilizers include substances which enable maintenance of a homogenous dispersion of two or more immiscible substances in a foodstuff and include also substances which stabilize, retain or intensity an existing colour of a foodstuff... 

Purification entails use of an immunoaffinity column containing immobilized murine antifactor VII antibody. It is initially produced as an unactivated, single chain 406 amino acid polypeptide, which is subsequently proteolytically converted into the two-chain active factor Vila complex. After sterilization by filtration, the final product is aseptically filled into its final product containers and freeze-dried. The excipients present in the product include sodium chloride, calcium chloride, polysorbate 80, mannitol and glycylglycine. When freeze-dried in the presence of these stabilizing substances and stored under refrigerated conditions, the product displays a shelf-life of at least 2 years. It has proved effective in the treatment of serious bleeding events in patients displaying anti-factor VIII or IX antibodies. 

The specific gravity of an 80% solution of hydrogen peroxide is 1.34. The solution is fairly stable at room temperature and decomposes only at an elevated temperature (the stability of hydrogen peroxide will be descussed later). To increase the stability of this solution, stabilizing substances such as phosphoric acid and its salts or 8-hydroxyquinoline were added. 

The ideas of the sequence of inversions are not quite consistent some authors have established slightly different sequences, probably as a result of differences in chemical composition and in the structure of the initial hydroxides. In principle, the modifications in question can be divided into two groups the first includes 7/, x 7-AI2O3. These forms arise at low temperatures (250—500 °C) and contain a certain amount of water (up to 2%) or other stabilizing substances. The d, 0 and /i-Al203 are formed at 800 — 1000 °C and contain only minute amounts of stabilizing admixtures. 

Some colloidal systems such as polymer solutions and surfactant solutions containing micelles are thermodynamically stable and form spontaneously. These types of colloids are called lyophilic colloids. However, most systems encountered contain lyophobic colloids (particles insoluble in the solvent). In the preparation of such lyophobic colloidal dispersions, the presence of a stabilizing substance is essential. Because van der Waals forces usually tend to lead to agglomeration (flocculation) of the particles, stability of such colloids requires that the particles repel one another, either by carrying a net electrostatic charge or by being coated with an adsorbed layer of large molecules compatible with the solvent. 

Vanadium(II) hydroxide is among the most powerful reducing agents known in inorganic chemistry. It is very unstable and extremely sensitive to atmospheric oxidation. In aqueous solution it is oxidized by water, unless some stabilizing substance such as thiocyanate or tellurate(IV) ion is present. ... 

The quantity of stabilizing substance may be increased to provide greater protection from atmospheric oxidation. For example, with the use of 30 to 40 ml. of potassium thiocyanate or tellurate(IV) (or a mixture of the two) it is possible to obtain the hydroxide in a form which may be filtered in air and dried for 17 hours on the filter funnel without oxidation. The stabilized hydroxide will return to its original unstable form by treatment with oxidation-accelerating substances such as tetrachloroauric(III) acid [hydrogen tetrachloroaurate(III)], copper(II) sulfate, or palla-... 

Most studies of aggregate formation, as already stated, have been made with surface soils that contain considerable organic matter and other stabilizing substances. This fact should be kept in mind continually in considering the discussion of aggregate formation that follows. Undoubtedly the presence of these stabilizing substances does under some conditions affect aggregate formation. 

Some systematic studies indieated that the previously known dependence of emulsion rheology on internal phase content and drop size charaeteristies eould be applied to pe-troleum-in-water emulsions (48). However, most early studies were not concerned with the presence of stabilizing substances like surfactants (49—51), so that they were missing an extremely important issue in practice. 

A final but very important point has to be mentioned. Commercial drugs contain, beside the active component several chemicals, such as coloring agents, antioxidants, and stabilizing substances which might also be potential allergens. 

The high stability of the suspension is confirmed by the values of electrokinetic potential whose absolute value in most cases is greater than 20 mV. Their negative sign is due to the fact that anions derived from stabilizing substances are adsorbed on particle surfaces. 

In processes in which sodium salicylate was used the presence of silver nanoparticles was confirmed when the silver concentration did not exceed lOOmg/dm. The higher concentration of silver ions requires the provision of more reducing-stabilizing substance. Sodium salicylate is used in an amount that... 

The advantage of the presented methods is the possibility of conducting the process of preparing nanometals without the need for adding stabilizing substances which would disperse nanosuspensions. The use of mentioned substances enables control of the size of nanoparticles. Their structure allows them to adsorb on nanosilver particles and thanks to that formation of agglomerates is inhibited. 

The typical nucleation mechanism coupled with high colloidal stability is achieved by the use of the stabilizing substances. The result is polymer particles with size comparable to nanoreactor precursors of the polymerization process, as shown in Fig. 8.4. Bearing this characteristic in mind, there is a need for optimal conditions of operation, mechanisms, and dispersion stability. These characteristics play a vital role on the particle morphology of the polymers obtained at the end of the process [26,34]. 

Using the three techniques described one might assume that they are suitable for all kinds of membrane fusion, however, there are two principal difficulties at first the relative broad range of the break-down potential of cells of different size and membrane ingredients. Since the cell diameter in our examples varies between 10 and 100 um, the fusion to hybridoma for instance requires the admixture of membrane stabilizing substances for the larger cells (and vice versa), otherwise the myeloma cells may undergo lysis. 

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