Aging method

ID ESRI experiments provided the concentration profiles of the nitroxides for the various aging methods and 2D spectral-spatial ESRI experiments described the spatial variation of the ESR spectra with sample depth, in terms of the variation of the fast/slow ratio with sample depth. In both ABS and HPEC samples, the variation of percentage fast with sample depth was translated... 

Rodriguez-Mendez, M. L., Apetrei, C., Villanueva, S., Apetrei, I. M., Nevares, I., del Alamo, M., Merino, S., Parra, V., Fernandez-Escudero, J. A., Iniguez, M., and De Saja, J. A. (2007). Monitoring the ageing of red wines by means of an electronic panel test Discrimination between traditional and alternative ageing methods. Bull. VOW 80 (911-913), 47-59. 

Among the numerous well-known aging methods, such as the oxygen-uptake test, the U-tube test, the use of differential thermal analyses to indicate the oxidation exotherm, oven aging proved to be one of the most versatile methods. Not only can many specimens of any size and shape be tested simultaneously, but samples can also be withdrawn at convenient intervals for inspection. 

Such contradictory results obtained by different aging methods suggest that one should use Arrhenius extrapolations to predict service life only with great reservation. Obviously aging tests should be run over a wide spectrum of temperatures and as near as possible to the anticipated end-use temperature of the resin. One way to shorten the duration of the test at lower temperatures is to use thin specimens, such as microtome cuttings. Figures 5 and 6 show that acceleration by an order of magnitude may be obtained. 

When accelerated-aging methods are used to predict long-term performance of products, the predictions are difficult to verify with natural-aging results. It is therefore desirable to ensure that the following criteria are met to generate reasonable confidence in accelerated-aging results ... 

The lack of an unambiguous method for demonstrating predictive validity of thermal accelerated-aging methods warrants extreme caution in extrapolating to long-term behavior for polymer-adhesive systems. The usefulness of such studies is often best applied to a ranking of preferred behavior under evaluative criteria. 

Some authors (Peinado et al. 2004a, 2004b Zea et al. 2007) have grouped aroma compounds in aromatic series based on their aroma descriptors. The overall value for each series is obtained by combining the odour activity value (OAV, which is defined as the ratio of the concentration of a compound to its perception thresholds) of the individual aroma compounds in the series. The combination of individual OAVs in order to calculate the overall value for a series cannot be interpreted as an arithmetic addition of odorant sensations. Some aspects of this classifying scheme can be subject to criticism, but in any case, the scheme is effective for comparing wines obtained with different aging methods inasmuch as the odour series always comprise the same compounds. 

For initially nonpremixed reactants, two limiting cases may be visualized, namely, the limit in which the chemistry is rapid compared with the fluid mechanics and the limit in which it is slow. In the slow-chemistry limit, extensive turbulent mixing may occur prior to chemical reaction, and situations approaching those in well-stirred reactors (see Section 4.1) may develop. There are particular slow-chemistry problems for which the previously identified moment methods and age methods are well suited. These methods are not appropriate for fast-chemistry problems. The primary combustion reactions in ordinary turbulent diffusion flames encountered in the laboratory and in industry appear to lie closer to the fast-chemistry limit. Methods for analyzing turbulent diffusion flames with fast chemistry have been developed recently [15], [20], [27]. These methods, which involve approximations of probability-density functions using moments, will be discussed in this section. 

The sol-gel technique uses mild conditions to prepare a cross-linked, robust metal oxide gel. Gelation of silanes, such as tetraethoxysilane (TEOS) or sodium silicate, involves the use of aqueous solutions, sometimes containing alcohol, with a slight adjustment of pH to catalyse the condensation polymerisation. The cross-link density, material porosity and homogeneity of functionalised sites, are dependent on the solution pH, extent of ageing, method of solvent evaporation, water content in solution and type of catalyst, all of which provide a number of handles to modify the material of interest. 

Hurley P. M. (1954) The hehum age method and the distribution and migration of hehum in rocks. In Nuclear Geology (ed. H. Paul). Wiley, New York, pp. 301-329. 

McFadden, L.D., Ritter, J.B. Wells, S.G. (1989) Use of multiparameter relative-age methods for age estimation and correlation of alluvial fan surfaces on a desert piedmont, eastern Mojave Desert. Quaternary Research 32, 276-290. 

Cacabelos R, Fernandez-Novoa L, Lombardi V, Kubota Y, Takeda M (2005) Molecular genetics of Alzheimer s disease and aging. Methods Find Exp Clin Pharmacol 27(Suppl A) l-573... 

Table I. The evaluation of polypropylene thermal oxidative stability by the chemiluminescence and oven aging methods at 150°C...

Aging of spirits involves oxidation. It is this reaction which one attempts to hasten by the processes devised for accelerated aging. Methods for aging spirits artificially fall into four main classes as follows (1) treatment with air, oxygen, or ozone (2) exposure to actinic rays (3) electrolytic treatment and (4) use of catalysts. Combinations of these methods are likewise employed. 

The time accelerated aging method for electric wires and cables requires a high dose rate irradiation, but the exposure to polymer in air results only the oxidation of surface when the dose rate is higher. I previously reported the methodology study of time accelerated irradiation of elastomer (2). The study showed two appropriate methods, one was irradiation in pressurized oxygen at room temperature the other was irradiation at 70°C in air. The article studied the effect of higher dose (up to 10 MGy) irradiation on ethylene-propylene-diene elastomer (EPDM) by using the time accelerated method. Irradiation at 70°C in air was chosen as the time accelerated irradiation condition because of the experimental convenience. 

Thermal aging method (a) An isotherm is generated at a temperature Ti until fully saturated in the (3 phase (above the plateau pressure). The sample holder is sealed and the sample heated to the aging temperature T2. Once the temperature is stabilized, then the sample is allowed to age for a certain period of time (b). If there is disproportionation, then the pressure rises and H/M decreases as function of time. 

Attempts to develop a reliable CRE age method for iron meteorites yielded inconsistent results except in one case which is a difficult, tedious, and no longer-practiced technique involving and stable and About 70 iron meteorites were dated by the method and their resulting ages range from... 

Hurley PM (1954) The helium age method and the distribution and migration of helium in rocks. In Nuclear Geology. Faul H (ed) John Wiley Sons, New York, p 301-329 Jonckheere R, Mars M, Van den hante P, Rebetez M, Chambandet A (1993) L apatite de Dnrango (Mexique) Analyse d un mineral standard ponr la datation par traces de fission. Chem Geol 103 141-154... 

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