Surface characteristics, influence

FTIR spectroscopy has proven to be particularly useful in gaining an understanding of the biocompatibility phenomenon. It is believed [746, 841, 856, 857] that protein adsorption is the initial step in the interaction of blood with implanted biomaterials, followed by adhesion of cells and subsequent tissue attachment. This implies that the substrate surface characteristics influence the process, which was confirmed by ATR studies of albumin adsorption on calcium phosphate bioceramics and titanium [763] and segmented polyurethane [764], albumin and fibrinogen on acetylated and unmodified cellulose [765, 766], poly(acrylic acid)-mucin bioadhesion [767], polyurethane-blood contact surfaces [768], and other proteins on poly(ester)urethane [769], polystyrene [767, 771] and poly(octadecyl methacrylate) [771] and by IRRAS study of adsorption of proteins on Cu [858]. Another branch of IR spectroscopic studies of protein adsorption relates to microbial adhesion (Section 7.8.3). 

The behavior of liposomes in vivo can be influenced to a considerable extent by varying chemical composition and physical properties. Parameters affecting rate of clearance from the blood and tissue distribution include size, composition, dose, and surface characteristics (e.g., charge, hydrophobicity, presence of homing devices such as antibodies). 

The surface characteristics of a batch of a drug substance may greatly influence its properties in processing (flow, dissolution). Crystals may crystallize in... 

Factors known to influence the clearance of drugs from interstitial sites, following extravasation or parenteral interstitial or transepithelial administration, include size and surface characteristics of particles, formulation medium, the composition and pH of the interstitial fluid, and disease within the interstitium. Studies indicate that soluble macromolecules smaller than 30 nm can enter the lymphatic system, whereas particulate materials larger than 50 nm are retained in the interstitial sites and serve as a sustained-release depot. The use of lipids or an oil in a formulation and the presence of a negative surface charge all appear to... 

We can define the principal electrical properties of polymers in terms of four characteristics electrical resistance, capacitive properties, dielectric strength, and arc resistance. We can change the surface characteristics of a polymer by subjecting it to a corona discharge generated by a strong electrical field. Lastly, we must also consider the influence of other physical properties on the application of polymers in electrical applications. 

Zeolite inner surface characteristics and influence on confined phases. 

Without any doubt, the zeolite framework porous characteristics (micropores sizes and topology) largely govern the zeolite properties and their industrial applications. Nevertheless for some zeolite uses, as for instance, host materials for confined phases, the zeolite inner surface characteristics should be precised to understand their influence on such low dimensionality sorbed systems. In that paper, we present illustrative examples of zeolite inner surface influence on confined methane phases. Our investigation extends from relatively complex zeolite inner surface types (as for MOR structural types) to the model inner surface ones (well illustrated by the AFI zeolite type). Sorption isotherm measurements associated with neutron diffraction experiments are used in the present study. 

Davies, N. A., Taylor, M. G. and Simkiss, K. (1997). The influence of particle surface characteristics on pollutant metal uptake by cells, Environ. Poll., 96, 179-184. 

In summary, the model proposed on the basis of acid-base characteristics of kaolinite platelets explains the pH-dependent charge primarily to the protonation of the hydroxyl groups at the basal gibbsite and the edge surface. We will later illustrate how this charge characteristics (surface protonation) influences the reactivity (dissolution characteristics) of kaolinite. 

Influence of Surface Area, Surface Characteristics, and Solution Composition on Feldspar Weathering Rates... 

To summarize, one can say that the electrochemical performance of CNT electrodes is correlated to the DOS of the CNT electrode with energies close to the redox formal potential of the solution species. The electron transfer and adsorption reactivity of CNT electrodes is remarkably dependent on the density of edge sites/defects that are the more reactive sites for that process, increasing considerably the electron-transfer rate. Additionally, surface oxygen functionalities can exert a big influence on the electrode kinetics. However, not all redox systems respond in the same way to the surface characteristics or can have electrocatalytical activity. This is very dependent on their own redox mechanism. Moreover, the high surface area and the nanometer size are the key factors in the electrochemical performance of the carbon nanotubes. 

The characteristics of particulate filled polymers are determined by the properties of their components, composition, structure and interactions [2]. These four factors are equally important and their effects are interconnected. The specific surface area of the filler, for example, determines the size of the contact surface between the filler and the polymer, thus the amount of the interphase formed. Surface energetics influence structure, and also the effect of composition on properties, as well as the mode of deformation. A relevant discussion of adhesion and interaction in particulate filled polymers cannot be carried out without defining the role of all factors which influence the properties of the composite and the interrelation among them. 

Although a number of filler characteristics influence composite properties, particle size, specific surface area, and surface energetics must again be mentioned here. All three also influence interfacial interactions. In the case of large particles and weak adhesion, the separation of the matrix/ filler interface is easy, debonding takes place under the effect of a small external load. Small particles form aggregates which cause a deterioration in the mechanical properties of the composites. Specific surface area, which depends on the particle size distribution of the filler, determines the size of the contact surface between the polymer and the filler. The size of this surface plays a crucial role in interfacial interactions and the formation of the interphase. 

Shah AC, Mlodozeniec AR. Mechanism of surface lubrication Influence of duration of lubricant-excipient mixing on processing characteristics of powders and properties of compressed tablets. J Pharm Sci 1977 66 1377-1381. 

Zeng XM, Martin GP, Marriott C, Pritchard J. Lactose as a carrier in dry powder formulations the influence of surface characteristics on drug delivery. J Pharma Sci 2001 90(9) 1424—1434. 

Ishida, H., Naviroj, S., Koenig, J. L. The influence of a Substrate on the Surface Characteristics of Silane Layers, in Physicochemical Aspects of Polymer Surfaces, Mittal, K. L. (Ed.) Plenum Press, New York 1982... 

Chemical parameters determine the surface characteristics of the suspended colloids, the concentration of the coagulant and its effects upon the surface properties of the destabilized particles, and the influence of other constituents of the ionic medium upon the coagulant and the colloids. The extent of the chemical and physical interactions between the colloidal phase and the solution phase determines the relative stability of the suspended colloids. One speaks of stable suspensions when all collisions between the colloids induced by Brownian motion or by velocity gradients are completely elastic the colloidal particles continue their... 

In addition, in polymeric compositions, i.e. in filled polymers, as a rule a broadening of the relaxation spectra takes place81. All these characteristics are closely associated with molecular parameters and free-volume, therefore it is interesting to consider how structural changes, induced in the same polymer by the action of the solid surface, may influence the applicability of the free-volume concept and the approach to such systems via the iso-free-volume state. In 82 the applicability of the... 

As indicated above, the goal in recent years in the ultra-large-scale integrated-circuit (ULSI) industry was to reduce contamination on surfaces to below the level detectable with state-of-the-art equipment. For economic and environmental reasons, this had to be replaced by one referred to as just clean enough. This requires that action-reaction-type relationships be identified between contaminants and their influence on a given surface in order to be able to fix acceptable levels of organic and metallic contamination, surface roughness, and other surface characteristics. 

Velbel, M. A. (1986). Influence of surface area, surface characteristics, and solution composition on feldspar weathering rates. ACS Symp. Ser. 323, 615-634. 

---