Suspensions factors affecting

The amount of adsorbed chemical is controlled by both properties of the chemical and of the clay material. The clay saturating cation is a major factor affecting the adsorption of the organophosphorus pesticide. The adsorption isotherm of parathion from an aqueous solution onto montmorillonite saturated with various cations (Fig. 8.32), shows that the sorption sequence (Al > Na > Ca ) is not in agreement with any of the ionic series based on ionic properties. This shows that, in parathion-montmoriUonite interactions in aqueous suspension, such factors as clay dispersion, steric effects, and hydration shells are dominant in the sorption process. In general, organophosphorus adsorption on clays is described by the Freundhch equation, and the values for parathion sorption are 3 for Ca +-kaoUnite, 125 for Ca -montmorillonite, and 145 for Ca -attapulgite. 

All the drugs in any solid dosage form or suspension when administered will first change into drug solution in body fluids. So, dissolution rate is important factor affecting the rate of absorption. 

The method of soil suspensions extracts is based on metal desorption/dissolution processes, which primarily depend on the physico-chemical characteristics of the metals, selected soil properties and environmental conditions. Metal adsorption/ desorption and solubility studies are important in the characterization of metal mobility and availability in soils. Metals are, in fact, present within the soil system in different pools and can follow either adsorption and precipitation reactions or desorption and dissolution reactions (Selim and Sparks, 2001). The main factors affecting the relationship between the soluble/mobile and immobile metal pools are soil pH, redox potential, adsorption and exchange capacity, the ionic strength of soil pore water, competing ions and kinetic effects (e.g. contact time) (Evans, 1989 Impelhtteri et al., 2001 McBride, 1994 Sparks, 1995). 

Formulation factors affecting the oral bioavailability from conventional dosage forms such as solutions, suspensions, emulsions, capsules and tablets are described here. 

Brown RC, Sara EA, Hoskins JA, et al. 1991. Factors affecting the interaction of asbestos fibres with mammalian cells a study using cells in suspension. Ann Occup Hyg 35 25-34. 

Composition of electroporation buffer is an important factor affecting electroporation yields. Ionic strength of cell suspension medium needs control, which determines resistance of the cell suspension and resultant RC time constant of the field pulse. Medium supplemented with Ca and Mg in mM concentration range is found to promote efficiency of transformation and cell viability. Erythrocytes electroporated in isotonic buffer in the presence of EDTA or membrane specific drugs showed significant modification in hemolysis response to electroporation [33,34]. Use of square wave pulse removes the medium conductivity mediated effects on cell/tissue electroporation outcome. Generally, cells are pulsed in suspensions of sucrose, mannitol, or sorbitol. Electroporation as well as incubation of pulsed cells can be carried out in medium containing usual cell culture recipes. 

Factors affecting drug absorption include formulation, disease state, food effect, and drug-drug interaction. Formulations used for oral administration include solutions, suspensions, capsules, and uncoated and coated tablets. Depending on the formulation of a drug, the absorption characteristics may differ substantially. 

As a rule, the problem of suspension stability is complicated by the fact that pharmaceutical suspensions are affected at least as much by physical as by chemical factors. 

Factors affecting H2 photoproduction by purple bacteria are described in this minireview. Based on comparison of maximum H2 photoproduction rates by suspension and immobilized cultures, it is concluded that immobilized culture is more attractive for application. Possibility for scaling up of photobioreactors with immobilized purple bacteria is discussed. 

The viscosity of slurries is a function of the solution and solid involved, as well as the slurry density. The viscosity can also be significantly affected by the particle size, size distribution, and particle shape. As a general rule, as particle shape varies from spheres to needles, the viscosity moves further from Newtonian behavior. A detailed discussion of factors affecting the viscosity of suspensions can be found in Sherman (1970). 

Mixing is an important factor affecting batch crystallization. On one hand, sufficient mixing is required to maintain crystals in suspension, to assure an adequate rate of energy transfer, and to achieve uniformity of suspension properties throughout the crystallizer. On the other hand, the effect of mixing on batch crystallization is largely system-dependent. 

Factors Affecting the Absorption of Drugs from Solid Dosage Forms and Suspensions... 

Table 6.3. Factors affecting the stability of soil colloidal suspensions...

Several therapeutically used penicillin preparations contain carbohydrates. Thus, penicillins are commonly infused in glucose or fructose solutions, sucrose is a common ingredient of penicillin syrups and benzylpenicillin procaine suspensions may contain carboxymethylcellulose as an additive. Because of the antigenic and potentially allergenic effect of penicilloyl-carbohydrate conjugates, their presence in penicillin preparations must be avoided. Information about the kinetics of reaction of penicillins with carbohydrate and factors affecting the reaction rate have recently been reported. 

Boltri, L., Canal, T., Esposito, P. and Carli, F., Relevant factors affecting the formation and growth of lipid nanosphere suspension, Eur. J. Pharm. Biopharm., 41, 70-75 (1995). 

A number of factors affect the rheology of emulsions composition, the viscosity ratio of the dispersed-to-matrix phase (1 s 7/2/771), the droplet size and its distribution, rheology of the interphase, and so on. Often, well-stabilized emulsions follow the viscosity-concentration relationships developed for hard sphere suspensions, including the yield phenomena. In contrast, emulsions with deformable dispersed... 

There are quite a few factors affecting sedimentation that we are yet to address. First and foremost, the equations considered so far do not take into account the design of the centrifuge, the concentration of the suspension, and the nature of the medium. All these complex factors do affect the sedimentation properties of a given particle. 

Hulubei Camelia, Vlad Cristina Doina, Stoica Juliana, et al. New polyimide-based porous crosslinked beads by suspension polymerization Physical and chemical factors affecting their morphology. J. Polym. Res. 21 no. 9 (2014) 514-530. 

Several theoretical and empirical relationships have been proposed to describe the viscosity of suspensions in Newtonian or non-Newtonian viscous liquids. These relationships have also been used, with ranging degrees of success, to correlate viscosity data when the suspending medium is viscoelastic [62]. In the following various relationships are reviewed. The viscosity of Newtonian as well as non-Newtonian suspensions is affected by the characteristics of the solid phase such as shape, concentration and dimensions of the particles, its size distribution, flie nature of the surface, etc. The influence of each of these factors is examined below. 

Consequently, two major factors affect the rheological properties of the mixture during phase separation (i) the change of composition in the epoxy-rich matrix and (ii) the variation of viscoelastic behavior of the phase-separated blend. The authors employed a two-phase suspension model as proposed by Graebling and Palierne [52] to explain the effect of viscoelastic behavior on the phase-separated mixture ... 

Capstick, P. B., A. J. Garland, W. G. Chapman, and R. C. Masters (1967). Factors affecting the production of foot-and-mouth disease virus in deep suspension cultures of BHK21 C13 cells, J. Hyg. Camb., 645, 273. 

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