Elements distribution

THE INVESTIGATION OF ELEMENTAL DISTRIBUTION IN DIFFERENT PARTS OF MYOCARDIUM IN HUMANS WITH IHD (SRXRF)... 

Nowadays the one of the leading cause of death in industrial country is Heart Failure (HF). Under the pathological conditions (e.g., Ischemic Heart Disease (IHD)) the changes in the enzymes activity and ultrastructure of tissue were obtained. The behavior of trace elements may reflect the activity of different types of enzymes. Pathological changes affects only small area of tissue, hence the amount of samples is strictly limited. Thereby, nondestructive multielemental method SRXRF allow to perfonu the analysis of mass samples in a few milligrams, to save the samples, to investigate the elemental distribution on the sample area. 

ESTIMATION OF SOME CHARACTERISTICS OF THE CHERNOBYL S INCIDENT ON ELEMENT DISTRIBUTIONS IN SAMPLES TAKEN FROM REACTOR CONCRETE CASING... 

The goal of our research was the comparison of the elemental content in cut part of nail and the part of nail, which contacts with the soft tissues of finger, the determination of elemental concentrations in 20 nails of individual, the determination of the elemental distribution as a dynamic mechanism. 

Often, more detailed information is needed on the distribution of a constituent. The technique of X-ray area scanning, or dot mappings can provide a qualirative view of elemental distributions. As the beam is scanned in a raster pattern on the specimen, a cathode ray rube scanned in synchronism is used to display a full white dot whenever the X-ray detector (WDS or EDS) detects an X ray within a certain narrow energy range. The pattern of dots is recorded on film to produce the dot map. Dot maps are subject to the following limitations ... 

Both XRF and EPMA are used for elemental analysis of thin films. XRF uses a nonfocusing X-ray source, while EPMA uses a focusing electron beam to generate fluorescent X rays. XRF gives information over a large area, up to cm in diameter, while EPMA samples small spots, (om in size. An important use of EPMA is in point-to-point analysis of elemental distribution. Microanalysis on a sub- lm scale can be done with electron microscopes. The penetration depth for an X-ray beam is normally in the 10-(om range, while it is around 1 (om for an electron beam. There is, therefore, also a difference in the depth of material analyzed by XRF and EPMA... 

Because a FIXE spectrum represents the int al of all the X rays created along the particle s path, a single FIXE measurement does not provide any depth profile information. All attempts to obtain general depth profiles using FIXE have involved multiple measurements that varied either the beam energy or the angle between the beam and the target, and have compared the results to those calculated for assumed elemental distributions. Frofiles measured in a few special cases surest that the depth resolution by nondestructive FIXE is only about 100 nm and that the absolute concentration values can have errors of 10-50%. 

Modern materials have a complex three-dimensional internal structure with many different phases. Although for these samples quantification is not possible, technologists are often interested in relative differences between several samples, or they already know the bulk concentrations and are only interested in the element distribution. 

Reduction of the measurement time for element distributions is possible by simultaneous detection of several masses. This can be achieved only by use of a magnetic sector field spectrometer with Mattauch-Herzog geometry [3.49] (Fig. 3.20) and parallel detection of up to five masses by mechanically adjusted electron multipliers. 

In practice image quality is also reduced by use of high mass resolution and energy offset. Often, therefore, mass interference cannot he avoided. Determination of element distributions is possible by use of image processing tools for classification of mappings of different masses [3.53]. 

Fig. 3.29. 3D element distribution of powder metallurgically produced steel. Diameter of the... 

SNMS is suitable for quantitative element depth profiling of metallic and electrically insulating samples. Laser-SNMS enables the additional acquisition of 2D element distributions with HF-plasma SNMS bulk analysis is also feasible. 

In EDXS the so-called spectrum-image method [4.122] can also be employed. A series of spectra is taken from a scanned rectangular field resulting in a data cube with its upper plane as the scanned x-y area and the third axis as the X-ray spectrum. Comprehensive information about the chemical composition and element distribution is extractable from this data set by subsequent processing. 

Fig. 4.30. Imaging of element distribution by X-ray mapping (a) cross-section STEM bright-...

Fig. 8.6. Elemental distribution maps of a shoek modified but unreaeted powder mixture in the work of Hammetter et al. [88H01] show that there is eonsiderable mixing of niekel into the aluminum.

Since the majority of the elements in surface dust arise from deposited aerosol and added soil it is not surprising to find strong linear relationships between the concentrations of the elements in an atmospheric dust and street or house dust. This is illustrated by the two examples given in Fig. 8 for remote house dust vs urban atmospheric dust and street dust vs rural atmospheric dust. As discussed above crustal/soil material is a major component of atmospheric dust and the soil based elements in the atmospheric dust are Al, Ca, Fe, Mg, Mn, Ni, K, Si and Ti. The elements As, Br, Cd, Cl, Co, Cu, Pb, Rb, Se, V, and Zn are, on the other hand, enriched in atmospheric dust. The same elemental distribution applies to surface dust, but in this case their concentrations (compared on a mass basis) are reduced presumably due to dilution with soil. However, the elements enriched in the atmosphere remain enriched in the surface dusts. 

The STM postulated tunneling matrix element distribution P(A) oc 1 /A implies a weakly (logarithmically) time-dependent heat capacity. This was pointed out early on by Anderson et al. [8], while the first specific estimate appeared soon afterwards [93]. The heat capacity did indeed turn out time dependent however, its experimental measures are indirect, and so a detailed comparison with theory is difficult. Reviews on the subject can be found in Nittke et al. [99] and Pohl [95]. Here we discuss the A distribution dictated by the present theory, in the semiclassical limit, and evaluate the resulting time dependence of the specific heat. While this limit is adequate at long times, quantum effects are important at short times (this concerns the heat condictivity as well). The latter are discussed in Section VA. 

The element distributions of Si, P, F, and Na within a dental silicate cement were recorded by Kent, Fletcher Wilson (1970) and Wilson et al. (1972) who used cements from which fine particles had been removed, and... 

Figure 6.19 Element distribution maps for a scanning electron micrograph of a dental silicate cement (a) optical micrograph of area of study, (b) Si distribution, (c) P distribution, d) A1 distribution (Wilson et at., 1972).

De Baar, H.J.W., German, C.R., Elderfield, H. and Van Gaans, P. (1988) Rare earth element distributions in anoxic waters of the Cariaco Trench. Geochim. Cosmochim. Acta, 52, 1203-1219. 

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