Contact duration

Hazardous substances are chemical substances with properties that may have certain harmful effects on humans and on the envirorrment upon contact or exposure. The risk arises from the degree of hazard presented by the substance (including any of its metabolites) as well as the nature and interrsity of contact (duration, dosage, absorption route, frequency). Hazardous substances in a legal sense are chemicals which must be classified as hazardous due to certain predefined criteria and available information or which have been classified as hazardous by official bodies. 

The collisional contact duration can be obtained by rearranging Eq. (2.130) to the form... 

When the deviation from the elastic state of the material surface is small, the Hertzian theory can estimate the force of impact, contact area, and contact duration for collisions between spherical particles and a plane surface using Eqs. (2.132), (2.133), and (2.136), respectively. To account for inelastic collisions, we may introduce r as the ratio of the reflection speed to the incoming speed, V. Therefore, we may write... 

On the basis of different effective longevities, anti-thrombogenic coatings are designed to adapt to variable blood-contacting durations. 

Source FDA General Program Memorandum G95-1 Contact duration ranges from 24 hours to 30 days. 

Body Contact (see 4.1) Contact Duration A Limited (24 h) B Prolonged (24 h to 30 days) C Permanent (>30 days) Cytotoxicity Sensitization Irritation or Intracutaneous Reactivity System Toxicity (Acute) Subchronic toxicity (Subacute Toxicity) Genotoxicity Implantation Haemocompatibility... 

Category Examples (not exclusive) Contact duration (A) Limited 24h (B) Prolonged Biological effect ... 

Contact duration Rolling (three-body) Sliding (two-body) Time (s)... 

Table 6 Medical device categorization by tissue contact and contact duration...

Figure 6,11 Dependence of carbon-13 atom magnetization, M(r), as a function of contact duration (Tj ( H) measurement) for a 50 50 PMMA/PVF2 blend, (o) blends cooled from 190°C to room temperature at a cooling rate of 0.2 /min ( ) blends cooled from 190°C to room temperature at a cooling rate of 10 /min. After [89].

All the.se sy.stcms are at once capillary and iiu rtial. and it Is ea.sv to dediure a few of their charaeteri.stics. A natural (jiu -stion to a.sk concern.s the contact duration upon. such impacts. It was first raLsed by Hertz in the case of solid/.solid collisions ac companu d by n bounds. E. perim( nt.s... 

Experiments and results. The viscoelastic material chosen was an optically smooth polyurethane, reconunended for dynamic studies in photoelasticity SM4 Vishay, with E = 3.6 MPa). The surfaces were wiped with an alcohol-soaked cloth, dried with warm air and left, sheltered from dust, for 30 min for the equilibrium with room temperature to be reached. Then, two strips of thickness /i=3.175 mm with various lengths L and widths b varying in the range 5-20 cm and S-20 mm, respectively, w e gently superimposed, and they adhered under only molecular attraction forces, without additional adhesive. In order to avoid the dwell time effect (/9), strips were coupled during the same contact duration 30 min, for all experiments. Moreover, temperature (23°C) and humidity (84%) were kept constant. In these conditions, the reproducibility is better than 3%. 

As expected, the knowledge of the function O allows one to predict the evolution of the system, among other things, the force involved and contact duration before rupture. Due to its elementary nature and also its sound validity, this model may be suitable for solving certain practical problems such as the ability of varnishes, paints, and coatings to adhere on deformable substrates. 

Consumption of the Electrogenerated Palladium Phase in Firm Contact with 0.1 mol.L" Csl after Contact Duration of the Phase with the Ji-Acceptor of 90 s ... 

FIGURE 11.5 The time correlation dependence in the fibrillar mats on water contact duration. 1 - the initial PHB mat, 2 - the same mat after cold-rolling. 

Yij the radius of the lens of fluid between two contacting or near contacting spheres, m the radius of the isothermal core used in Model B, m Re, local relative Reynolds number for particle i, dimensionless Rj radius of particle i, m Rj radius of particle j, m Rjj mean radius of particles i andj, m tc collision contact duration between particles i and j, s tj static contact duration between particles i and j, s Te the environmental temperature, K Tj, bed temperature, K... 

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