Effect of exposure time

Owing to the laborious task of obtaining corrosion rates from gravimetric measurements, data for the effect of exposure time on corrosion rates have been very limited. However, with the more recent use of polarisation resistance measurements it would appear that in the absence of macro-biofouling... 

The effect of exposure time on the corrosion of copper and aluminium is illustrated in Table 2.17. The results quoted by Southwell, Hummer and... 

Figure 4. Effect of exposure time on CPE n-value and relative surface area.

When step (a) reaches equilibrium, both and 8 should have steady state values. To test this hypothesis, we determined the effect of exposure time on and 8 for N80 steel in 15% HC1 at 25 C and in 28% HC1 at 65 C, as shown in Figures 6 and 7, respectively. Here [octynol] = 3.5 x 10"% in 15% HC1 and 2.1 x lO"2 in 28% HC1. It is immediately apparent from these plots that neither nor 8 reaches a steady state value during the course of the experiments. Although appears to be relatively constant throughout the 15% HC1 test and during the first stage of the 28% HC1 test, it is continually increasing in both cases. 

Figure 18.14 Effect of exposure time on the color versus depth profile in Spectar copolymer sheeting (3 mm) exposed in New River, AZ [10]. From Photodegradation in a copoly(ethylene/1,4-cyclohexylenedimethylene tereph-thalate) with and without UV absorber, presentation given by D. R. Fagerburg at the 37th International Symposium on Macromolecules, IUPAC World Polymer Congress, Gold Coast, Australia, July 1998, and reproduced with permission of IUPAC...

To examine the effect of exposure time on the lad mutant frequency in butadiene-exposed mice, Recio et al. (1996) exposed male B6C3F, lad transgenic mice by inhalation to 625 or 1250 ppm butadiene for 6 h per day for five days. Mice were killed 14 days following the last exposure and mutant frequency in the bone marrow was determined. The authors reported a five-fold increase in the lad mutant frequency in mice exposed to 625 ppm butadiene compared with air control mice. These results demonstrated that there was little difference in the bone marrow lad mutant frequency between a short-term exposure and the long-term exposure used in the previous study. 

Mathematical models have been developed and used to extrapolate toxicity under pulsed exposure conditions (for an overview, see Boxall et al. 2002 Reinert et al. 2002 Ashauer et al. 2006 Jager et al. 2006). Some models consider concentration x time (Meyer et al. 1995) others, uptake and depuration (Mancini 1983) or damage and repair (Breck 1988). Several models are based on the concept of critical body residues, which integrates toxicokinetics and the effects of exposure time on toxicity (McCarty and Mackay 1993 Barron et al. 2002). This approach is promising because several studies showed that toxicity from pulse exposures is largely... 

Figure 9-11 Effect of Exposure Time at Light Intensity of 200 Ft-C on the Loss of Ascorbic Acid in Milk. Packaging materials (1) clear plastic pouch, (2) laminated nontransparent pouch, (3) carton, (4) plastic 3-quart jug. Source From A. Sattar and J.M. deMan, Effect of Packaging Material on Light-Induced Quality Deterioration of Milk, Can. Inst. Food Sci. Technol. J., Vol. 6, pp. 170-174,1973.

Sheets of PVC were subjected to argon plasma immersion ion implantation over various exposure times (from 900 to 10,800 s) and the effect of exposure time on the composition, roughness and wettability of the PVC sheets investigated. It was found that the wettability of samples increased with surface treatment and that the hydrophobic character of samples treated for shorter periods recovered either partially or completely. Samples exposed for the longest time remained highly hydrophilic. 21 refs. BRAZIL... 

Figure 2. Effect of exposure time, E, upon weight gain with constant ozone concentration...

W.L. Backes at the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, is studying the toxicological significance of the metabolism in rats and rabbits of alkylbenzenes (including toluene, xylenes, ethylbenzene, and />propylbenzene), which are major constituents of gasoline. Specifically, the identification of changes in the metabolic fate of the alkylbenzenes due to their prior administration, the effects of age, sex, and strain differences, the effects of exposure time and exposure to hydrocarbon mixtures, and the effect of hydrocarbon... 

The exposure time was originally selected because the anticipated test length was only a few seconds. It was felt that an hour of temperature exposure would well exceed the lifetime of any experimental test series. This exposure time was selected to make this work consistent with earlier research.To date, no research had been completed comparing the effects of exposure time at temperature to the magnitude of fluorescence emission. It was decided to complete a series of tests with a single binder to determine the relationship between temperature exposure time and normalized emission intensity for a Y2O3 Eu and Resbond 793 TSP. 

Effect of Exposure Time on Oil Volatility In Modified Selby-Noack Tests... 

Effects of Exposure Time on Otherwise Normal Test Technique... 

To determine the effect of exposure time on the CR and the resistance performance, steel specimens were immersed in 0.1 M HCl solution at three exposure times, namely, 24, 48, and 120 h for DPP and 100, 163, and 224 h for RBP. Tables 7.3 and 7.4 summarize the weight loss experimental results at different exposure times for DP and RB processes, respectively. Weight loss decreases with increasing pressing force up to 80 N but increases at higher pressing forces. This means that the optimum force is about 80 N. 

The effect of exposure time on residual strength is shown in Figure 3 and on the strain to failure is illustrated in Figure 4 along with data fiom standard samples as reference. Figure 5 shows the change of the value of strain to failure with the exposure strain for samples with and... 

The effect of exposure time, e. g., life long environmental low exposure or occupational intermittent high exposure. 

The duration of the test can have a significant effect on the test data. Most materials wiU corrode most rapidly in the early stages of exposure to an enviromnent—before oxide films are developed that may inhibit the corrosion rate by limiting the diffusion rate of reacting species to and from the metallic surface. Thus, tests of 24-h duration extrapolated to 30-day or f-year behavior may be extremely conservative. Where time allows, multiple test durations may be evaluated to determine the actual effect of exposure time on uniform corrosion. 

Effect of Exposure Time It is obvious from Table 3.1 that as the time of irradiation changes gel formation changes. In the MW-initiated technique, time of irradiation is an input parameter. In MW-assisted technique, it is an output parameter, where as the CAN concentration increases, exposure time (up to gel formation) decreases. 

G.T.G. Mohamedbhai. Effect of exposure time cuid rates of heating and cooling on residual strength of heated concrete. Magazine of Concrete Research, 38(136), pp. 151-158,1986. 

Effect of Exposure Time between Casting and Precipitation... 

FIGURE 8.8 The effect of exposure time under humid atmosphere (RH = 60%) before immersion in coagulation bath of the PVDF/(TEP/DMA)/water system with 15% PVDF concentration. SEM images show the impact on the resulting membrane structure. (Data from Li, Q. et al., Polymers for Advanced Technologies, 22,520-531,2011. doi 10.1002/pat.l549.)... 

Effect of Exposure Time. A very important characteristic of weathering of aluminum and of corrosion of aluminum under many other environmental conditions is that corrosion rate decreases with time to a relatively low, steady-state rate (Ref 8). This deceleration of corrosion, often referred to as self-stopping or self-limiting corrosion, occurs regardless of alloy composition, type of environment, or the parameter by which the corrosion is measured (see, for example. Fig. 2, 3, 5, 6, 8, and 9). However, loss in tensile strength, which is influenced somewhat by pit acui and distribution but is basically a result of loss of effective cross section, decelerates more gradually than depth of attadc (Fig. 8). 

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