Solubility and influence

Bettini, R., Catellani, P., Santi, P., Massimo, G., Peppas, N., and Colombo, P., Translocation of drug particles in HPMC matrix gel layer Effect of drug solubility and influence on release rate, Journal of Controlled Release, Vol. 70, No. 3, 2001, pp. 383-391. 

As it is the case for titanium, oxygen acts as an alloying element with very high solubility and influences mechanical strength (Table 1-2). 

Volatilization. The susceptibility of a herbicide to loss through volatilization has received much attention, due in part to the realization that herbicides in the vapor phase may be transported large distances from the point of application. Volatilization losses can be as high as 80—90% of the total applied herbicide within several days of application. The processes that control the amount of herbicide volatilized are the evaporation of the herbicide from the solution or soHd phase into the air, and dispersal and dilution of the resulting vapor into the atmosphere (250). These processes are influenced by many factors including herbicide application rate, wind velocity, temperature, soil moisture content, and the compound s sorption to soil organic and mineral surfaces. Properties of the herbicide that influence volatility include vapor pressure, water solubility, and chemical stmcture (251). 

Both the chemical solubility and the electrical properties are consistent with those expected of a lightly polar polymer, whilst reactivity is consistent with that of a polymer containing hydrolysable carbonate ester linkages partially protected by aromatic hydrocarbon groupings. The influence of these factors on specific properties is amplified in subsequent sections. 

Despite the fact that the two main components of UF-resins are urea and formaldehyde, a broad variety of possible reactions and structures in the resins can be obtained. At the molecular level, the basic characteristics of UF-resins can be explained as follows (1) high reactivity (2) water solubility and dispersibility, which renders the resins ideal for use in the woodworking industry and (3) the reversibility of the aminomethylene link, which also explains the low resistance of the UF-resins against the influence of water and moisture, especially at higher temperatures. This is also one of the reasons for the subsequent formaldehyde emission. 

Other properties that are influenced by H bonding are solubility and miscibility, heats of mixing, phase-partitioning properties, the... 

Consistent with this, even KI3 is rapidly decolorized in alkaline solution. The example is a salu-tory reminder of the influence of pH, solubility, and complex formation on the standard reduction potentials of many elements. 

Aromatic denitrocyclizations have been used for many years in some well-known synthetic reactions. Probably the best known example is the Turpin synthesis of phenoxazines and similar synthesis of phenothiazines. The classical setup used usually base-catalyzed reactions in polar protic solvents, very often alcohols. In many cases using polar aprotic solvents was found advantageous. Besides the mentioned influence of the H-bonding, better ionization and lower solvation of the nucleophile are also important. Sf Ar reactions proceed through strongly polarized complexes, which are well soluble and highly polarized in polar aprotic solvents. 

Nabitan (39) is a cannabis-inspired analgesic whose nitrogen atom was introduced in order to improve water solubility and perhaps to affect the pharmacological profile as well. The phenolic hydroxyl of benzopyran synthon is esterified with 4-(l-piperidino)butyric acid under the influence of dicyclohexyl carbodi mi de. In addition to being hypotensive and... 

The level of DO in water is primarily a function of temperature and pressure, but salt concentration (or TDS) and some other parameters can influence oxygen solubility, and some variation may occur. Nevertheless, a good approximation is shown in Table 11.1. 

The most common backbone structure found in commercial polymers is the saturated carbon-carbon structure. Polymers with saturated carbon-carbon backbones, such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyacrylates, are produced using chain-growth polymerizations. The saturated carbon-carbon backbone of polyethylene with no side groups is a relatively flexible polymer chain. The glass transition temperature is low at -20°C for high-density polyethylene. Side groups on the carbon-carbon backbone influence thermal transitions, solubility, and other polymer properties. 

Both the main chain and side chains can greatly influence die properties of polymers. By varying the side chains and using different linkers, properties of polymers such as die solubility and conjugation along the polymer backbone can be greatly altered. 

The use of SCFs as solvents influences the reacting system because it is possible to dramatically change the density of the fluid with small perturbations of temperature and pressure and, in such a way, greatly affect the density-dependent bulk properties such as the dielectric constant, solubility and diffu-sibility of these compressible fluids. 

The presence of a large number of chain-ends in the fully synthesized dendrimer molecules makes them highly soluble and also readily miscible, for example with other dendrimer solutions. The solubility is controlled by the nature of the end-groups, so that dendrimers with hydrophilic groups, such as hydroxyl or carboxylic acid, at the ends of the branches are soluble in polar solvents, whereas dendrimers with hydrophobic end-groups are soluble in non-polar solvents. The density of the end-groups at the surface of the dendrimer molecule means that they have proportionately more influence on the solubility than in linear polymers. Hence a dendritic polyester has been shown to be more soluble in tetrahydrofuran than an equivalent linear polyester. 

Absorption across biological membranes is often necessary for a chemical to manifest toxicity. In many cases several membranes need to be crossed and the structure of both the chemical and the membrane need to be evaluated in the process. The major routes of absorption are ingestion, inhalation, dermal and, in the case of exposures in aquatic systems, gills. Factors that influence absorption have been reviewed recently. Methods to assess absorption include in vivo, in vitro, various cellular cultures as well as modelling approaches. Solubility and permeability are barriers to absorption and guidelines have been developed to estimate the likelihood of candidate molecules being absorbed after oral administration. ... 

There are several factors through which anions can influence the pathway and O2 reduction kinetics. The main factors are competition with O2 for surface sites changes in the activity coefficients of the reactants, intermediates, and transition states and the acidity and dielectric properties of the electrolyte side of the interface [Adzic, 1998]. For example, perfluoro acids have higher O2 solubility and lower adsorbability than... 

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