Dynamic Contact Conditions

The antibacterial efficacy of Ppy deposited on cotton fabrics was quantitatively evaluated under dynamic contact conditions according to the American Society for Testing and Materials (ASTM), ASTM E2149-01. Moreover, the bactericidal mechanism of Ppy on Escherichia coli bacteria was preliminarily investigated [55]. 

ASTM E2149-10 Standard Test Method for Determining the Antimicrobial Activity of Immobilized Antimicrobial Agents under Dynamic Contact Conditions. 

Annual Book of ASTM Standards V 11.05, ASTM E2149-01, Standard Method for Determining the Antimicrobial activity cf Immobilized ArOimicrobial Agents Under Dynamic Contact Conditions, Pennsylvania 2005. 

American Society for Testing and Materials. ASTM E2149-10 standard test method for determining the antimicrobial activity of immobilized antimicrobial agents under dynamic contact conditions. Pennsylvania ASTM IntemationaL PA 2001. 

Adsorption for gas purification comes under the category of dynamic adsorption. Where a high separation efficiency is required, the adsorption would be stopped when the breakthrough point is reached. The relationship between adsorbate concentration in the gas stream and the solid may be determined experimentally and plotted in the form of isotherms. These are usually determined under static equilibrium conditions but dynamic adsorption conditions operating in gas purification bear little relationship to these results. Isotherms indicate the affinity of the adsorbent for the adsorbate but do not relate the contact time or the amount of adsorbent required to reduce the adsorbate from one concentration to another. Factors which influence the service time of an adsorbent bed include the grain size of the adsorbent depth of adsorbent bed gas velocity temperature of gas and adsorbent pressure of the gas stream concentration of the adsorbates concentration of other gas constituents which may be adsorbed at the same time moisture content of the gas and adsorbent concentration of substances which may polymerize or react with the adsorbent adsorptive capacity of the adsorbent for the adsorbate over the concentration range applicable over the filter or carbon bed efficiency of adsorbate removal required. 

The basic theories of elastic deformations associated with various contact forces under static contact conditions have been introduced in the last section. Assuming that an impact process of two solids can be regarded as quasi-static, the theories given in 2.3 are used directly to link the dynamic deformations of the colliding solids with the impact forces. In this section, the collisions of elastic spheres are described. 

From the results shown in Table 3 and the textural characteristics of the adsorbents presented in Table 2 several conclusions may be drawn. Under these dynamic adsorption conditions with a contact time of <1 second the most favourable conditions lead to the amount adsorbed before breakthrough being equivalent to the micropore volume of the adsorbent. Thus, it would appear that the organic is stored in the micropores. However, this condition may only be met if other textural properties of the monolithic adsorbent are also present. For samples ChFc-m/a and ChFc-m/b, with external areas of c.l20 m g the dynamic adsorption capacity was equal to the micropore volume. But for sample ChFc-m/c with an external area of 90 m g the dynamic adsorption capacity was only 75% of the micropore volume. Thus, a high external area was necessary. This was confirmed by the results obtained with NoGp-m/b and NoGp-m/c where the dynamic capacity was equal to the micropore volume even when the external area was reduced to 110 m g. ... 

The intrinsic complexity of additive/metal interactions under dynamic rubbing conditions probably means that the description and analysis of additive action even in fairly simple tribological situations will not be entirely free of conjecture. The difficulties in the elucidation of additive/metal interaction are illustrated by the work of Buckley [7, 8, 13] for no matter how elegantly the presence of the active element (sulfur, chlorine, carbon) in the surface of the metal is demonstrated, it does not reveal the path by which that element got there from the additive substance as originally put into the system. The appropriateness of a conjecture or an experimental investigation can be tested by questions such as the following How is the initial encounter of the additive molecule with the metal surface treated What is known about the interaction immediately subsequent to the initial encounter How is the interaction affected by the duration of contact and by the local temperature Is there further interaction, of the additive and secondary products or of secondary products directly, with the metal surface ... 

We conclude this discussion by alerting the reader to the concept of the dynamic contact angle (and line), which appears in the literature of flows governed by surface tension (Dussan V. 1979). In a flow field where the contact line moves, it is necessary to know the contact angle as a boundary condition for determining the meniscus shape. If this angle is a function of the speed of the contact line relative to the solid surface, then the force balance inherent in... 

Figure 10.10 Experimental transfer ratios (TR) versus dynamic contact angles during down-strokes for different pH values. The conditions of deposition were as follows a surface pressure of 25 mN/m, 26° C, and a deposition speed of 19mm/min. The values of the pH were as follows pH = 5.3 (diamonds) pH = 6.6 (star) pH=7.7 (cross) pH = 8.7 (open circle) pH = 9.4 (asterisk) pH =10.1 (x) pH = 10.6 (open triangle). The line is just a guide to the eye...

Hemocompatibility tests evaluate effects on blood and/or blood components by blood-contacting medical devices or materials. In vivo hemocompatibility tests are usually designed to simulate the geometry, contact conditions, and flow dynamics of the device or material in its dinical application. From the ISO standards perspective, five test categories are indicated for hemocompatibility evaluation thrombosis, coagulation, platelets, hematology, and immimology (complement and leukocytes) (Table 12). 

A dynamic contact angle condition can then be written for the macroscopic spreading drop ... 

It is now possible to insert this dynamic contact angle condition back into the spreading relationship in Eq. 15 to obtain an explicit power law for the spreading dynamics of a drop lying on a horizontal substrate [7]. If the drop can be assumed to be thin, then the axisymmetric Laplace-Young equation in the lubrication limit reads... 

Substitution of the dynamic contact angle condition in Eq. 20 then gives... 

The problems involving dynamic contact lines contain additional difficrrlties that arise from the fact that these lines describe the intersection of two strrfaces. The physical problem can require two different types of botmdary conditions to be satisfied, one condition on each of the strrfaces. However, both need to be satisfied... 

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