Quantification of changes

The nano-scale structures in polymer layered-silicate nano-composites can be thoroughly characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD is used to identify intercalated structures. XRD allows quantification of changes in layer spacing and the most commonly used to probe the nano-composite structure and... 

Quantification of changes in soil carbon dynamics, including SOM turnover rate and distribution of SOC with depth, is therefore critical for determining carbon storage in soils and for modeling soil carbon cycling. 

Boneneant, D., Schmeizle, T, Jacinto, E., Crespo, J. L., Mini, T, Hall, M. N., Jenoe, P. (2003). Quantification of changes in protein phosphorylation a simple method based on stable isotope labeling and mass spectrometry. Proc. Natl. Acad. Sci. USA 100, 880-885. 

In the proteomic analysis of the brain, two-dimensional gels for protein separation, followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry for protein identification, have mainly been employed. This classical proteomics approach allows for the quantification of changes in protein levels and modifications. Simultaneously, it is a robust, well-established method that finds wide application in the study of biological systems. In this article, we provide a description of the protocols of the proteomic analysis used in our laboratory and a summary of the major findings from our group and other neuroproteomics groups. 

Most proteomics analyses involve 2-D electrophoresis and MALDl-TOF MS steps, as this approach allows for a reliable quantification of changes in protein levels. In one study, the LC-MS/MS approach was used for the detection of proteins enriched in amyloid plaques in the AD brain (liao et al., 2004). Employing the former proteomic approach, levels of about 100 proteins were foimd to be changed in the AD brain and cerebrospinal fluid (CSF) in comparison with the control brain and CSF, respectively (Table 15.1). These proteins have various functions, mainly involved in neurotransmission, guidance, signal transduction, metabolism, detoxification, and conformational changes. The CSF proteins are plasma proteins. 

Chemical probes for quantification of changes in protein activities... 

Major result Metabohte classification Relative quantif of change in metabolite pool, discovery of biomarkers, novel metabolites Absolute quantif of metabolite pools Quantif of metabolite flux... 

Industries that have a reliance on materials have a burdensome responsibility to ensure constant quality. Reliability comes from knowledge of the process of change and the predictions about change resulting from environmental conditions. Like freshly baked bread, most materials are at the highest quality at the time of manufacture but depreciate with time. Since it is important to understand change, effort and money are therefore invested in an attempt to ensure quantification of change. This provides the basis for a shelf life specification and recommendation for the conditions under which a material can be used. 

Both TEM and WAXD are essential tools for evaluating nanocomposite structure. However, TEM is time-intensive and only gives qualitative information on the sample as a whole, whereas wide-angle peaks in WAXD allow quantification of changes in layer spacing. Typically, when layer spacing exceeds 6-7 nm in intercalated nanocomposites or when the layers become relatively disordered in exfoliated nanocomposites, associated WAXD features weaken to the point of not being useful [133]. 

The fluorescence properties of pyrene and its derivatives depend on the microscopic concentration of the fluorophore in the lipoprotein, thus allowing both continuous monitoring of the kinetics of transfer and quantification of changes in mass, as well as obviating physical separation of reactants and products. The excimer/monomer ratio is linear with concentration (Pownall and Smith, 1973) and decreases with probe transfer from a donor to an acceptor lipoprotein (Fig. 16). 

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