Weathered samples

The formation of the major UV degradation peak at about 287 nm in the weathered PC appears to correlate well with the formation of the yellow color in the weathered sample. In Figure 8 the formation of both the peak at 287 nm and the yellow color have been assumed to be products of a first order reaction. This figure shows a plot of the log of the percentage of a scaling constant minus the yellowness index divided by the constant, versus a measurement of the exposure. In this case, the exposure is expressed as cal/cm2, obtained from ENC0N data. 

In this work, 6 Lac Tio waste rock samples are investigated 3 samples were freshly blasted waste rock and 3 were weathered samples from an old waste rock pile (approximately 25 years old) which underwent significant natural alteration. The ilmenite content varies from approximately 20 to 60 wt% in both... 

Chromatographic Evidence Sample chromatograms often contain evidence that natural attenuation has occurred. If chromatograms of fresh petroleum that was released can be obtained, then a solid comparison can be made between fresh and weathered samples relatively soon after being released in many circumstances. 

We also note data from atomic force microscopy (AFM) versus depth, carried out by using a diamond tip for scratching patterns into the surface [12], Because of the 2° microtoming method reported, these authors were able to examine the depth profile of brittle behavior in weathered samples with excellent resolution. The data showed a very rapid decrease in the brittleness with depth into the sample which, of course, was a strong function of exposure time. The brittleness was more in line with the IR data (see above) versus depth than the molecular weight data, hence suggesting that some chain scission and branching can be tolerated in the system before it manifests brittle behavior. 

Rock samples were collected from measured sections. Weathered samples were avoided as far as possible, and weathered crusts were later removed in the laboratory. The samples were thoroughly cleaned, treated with chromic acid, crushed, powdered in porcelain ball mills, and stored in glass jars. 

Mr. Zubovic. We have not made any additional studies of these weathered samples. I do not know if there is any correlation of the elements with a larger number of acidic groups in this coal. I do believe that the additional amounts of elements found in the weathered coals are not held there as chelates but rather as simple complexes such as are formed in ion exchange reactions. 

Element Weathered Samples (4) Unweathered Samples (32) Ratio, Weathered/ Unweathered... 

However, the author believes that the metals in the weathered samples are held in ion exchange positions or as simple salts of the organic matter rather than by chelation, and that the accumulation of these abnormally large amounts of most of the elements was synchronous with the weathing process. Data from these samples suggest that basing minor element distribution in carbonaceous rocks on data from weathering samples could lead to erroneous interpretation. 

Dr. Murchison Oxidation of the resinite from lignitous coal does seem to cause broadening of the CO absorption and makes the appearance of this band very similar to that in the spectrum of the oxidized layer from a weathered sample. It is too early to say whether or not this a general feature that affects all oxidized resinite. The possibility of quinone formation during oxidation has not been studied. 

Cherts and quartzites are generally believed to be a poor environment for the growth of microorganisms. However, some authors found modem contamination in weathered samples taken from such facies. Nagy et al. (1981)6S) examined... 

In weathered samples of the Isua quartzite, most carbonaceous material has been leached out along with the associated carbonates, leaving spherical cavities in the place of the Isuaspheres. These have been mistaken for fluid inclusions by... 

Discrepancies between reactive and adsorption surface area may also be related to the presence of deep etch pits or pore outcrops which can constitute transport-limited micro-environments for dissolution (Jeschke and Dreybrodt, 2002). Much of the BET surface area for some alkali feldspars used for dissolution in the laboratory has been attributed to grinding-induced microporosity (Hodson et al, 1999), and such pore outcrops are candidates for transport limitation. If such induced surfaces react dilferently than surfaces of weathered samples, then the BET surface area may be an inappropriate parameter to use for extrapolating interface-limited kinetics from laboratory to field (Lee et al, 1998 Brantley and Mellott, 2000 Jeschke and Dreybrodt, 2002) and consideration may need to be given to length and extent of grinding for laboratory samples (Hodson, 1999). It may be more appropriate to use geometric rather than BET surface area to extrapolate kinetics for samples where etch pits or pore outcrops are important contributors to BET surface area (Gautier et al, 2001 Jeschke and Dreybrodt, 2002 Mellott et al, 2002). 

Figure 11 Measured dissolution rate for plagioclase from Panola granite, Georgia, USA compared to published dissolution rates of other plagioclase samples. Panola plagioclase was dissolved either as fresh unweathered samples, or as naturally pre-weathered samples (see text). Also plotted are dissolution rates for plagioclase under ambient conditions in the laboratory at near-neutral pH for freshly ground samples from other localities (solid symbols) and for samples weathered naturally in other field localities and then dissolved in the laboratory (open symbols). All rates were normalized by BET surface area. Dashed line is a fit to all field and laboratory data, including field data from systems weathering for periods of time 1 yr (data not shown). Figure adapted from White and Brantley (2003), and all data are attributed in that paper.

Infrared and Raman spectroscopy, coupled with optical microscopy, provide vibrational data that allow us to chemically characterise geochemical sediments and weathered samples with lateral resolutions of 10-20 pm and 1-2 pm respectively. Fourier transform infrared spectroscopy involves the absorption of IR radiation, where the intensity of the beam is measured before and after it enters the sample as a function of the light frequency. Fourier transform infrared is very sensitive, fast and provides good resolution, very small samples can be analysed and information on molecular structure can be obtained. Weak signals can be measured with high precision from, for example, samples that are poor reflectors or transmitters or have low concentrations of active species, which is often the case for geochemical sediments and weathered materials. Samples of unknown... 

A standard Paint Research Institute latex paint, provided by J. F. Matthews of DuPont, was the reference sample to which the biocidal latex polymers were compared. After two months both the unweathered and weathered samples showed moderate or moderate to heavy growth on the paint surface. The unweathered samples showed severe stain intensities on basswood. The weathered samples showed medium stain intensities on both. When coatings of an MMA/nBA latex blended with a MMA/nBA/8 terpolymer latex were tested, only trace growth of Aureobasidlum pullulans on the coatings was observed using pine or basswood substrates. 

Figure 11. Differential spectra resulting in a wef weather sample fractionation [18],...

Figure 17 Glazed ceramic samples in the process of weathering a non-weathered sample (left) and proceeding damage on the glaze after accelerated weathering (middle and right)...

The major conclusion of the interlaboratory study confirms our growing belief in the necessity for a simple, standard method for accelerated or simulated weathering in the laboratory of suspect samples prior to comparing them with spill samples. All of the methods were better able to. match weathered samples with other weathered samples of the same oil than they were to the unweathered oil. 

Gruenfeld and Frederick (31) developed an evaporative method that can be used for samples as small as 70 mg. The sample, contained in a vial, is suspended in a 40° C water bath for 15 min in the presence of a filtered airstream. Gas chromatograms of the weathered sample showed that it gave virtually the same trace as a 50-mL sample distilled according to the ASTM sample preparation technique. Even more remarkable is the fact that they obtained the same trace from 0.5-30 mg of oil that had been dispersed in water and was extracted and evaporated, that is, they were able to match a sample of South Louisiana crude oil from the water column with a neat sample of oil that had been weathered. ... 

The vector, referred to in Table I, alludes to a promising new pattern recognition technique developed by Killeen et al. (45). It uses the data from a suspect and a partially weathered sample of the suspect to estab-... 

Yes, Differences possibly caused by weathering/ sample inhomogeneity,... 

FIGURE 27.8 GC traces of the saturated fractions of the weathered source oil (top), the moderately weathered sample 1 (middle), and the severely weathered sample 2 (bottom) from the Baffin Island Oil Spill project conducted at Baffin Island in the Canadian Arctic from 1980 to 1983, illustrating the effects of over 15 years field weathering on chemical composition changes and the weathering trend of the spilled oil. IS, pr, and ph represent the internal standard, pristane, and phytane, respectively. 

Generally, the recognized ore zones are primarily phosphorites whereas strata in the waste zones include more dolostones and silicic layers. Factor analysis to determine the relationships of the lithology and the COs content in CFA considered four variables (1) the degree of COs substitution for P04 in CFA, (2) CFA content, (3) silicate mineral content (quartz + sheet silicates + feldspars), and (4) carbonate mineral content (dolomite + calcite). Because the more-, and less-weathered strata have lost much of their original carbonate mineral content, only the least-weathered samples are used for factor analysis, as they are the best proxy for the unweathered Phosphoria Formation. 

The silicone polymer backbone is composed of Si-O-Si bonds. This bond is very strong and stable with a bond energy of 87 Kcal/ mole. The polymer can tolerate 250°C to 300°C without decomposing.— The fully compounded silicone sealant, when cured to a rubber, can withstand 200°C for sustained periods of time with no special additives and even higher temperatures with polymer modifications and/or heat stability additives.— The Sl-O-Si molecular structure is also transparent to U.V., so silicone sealants are virtually unaffected by weather. Samples of silicone sealants used in exterior construction applications have been tested after 20 years of actual performance. These samples exhibited essentially no change in physical properties or adhesion during that time period. 

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