Causes of heterogeneity

Rude, R. K. (1998). Magnesium deficiency A cause of heterogenous disease in humans. /. Bone Miner. Res. 13, 749-758. 

A similar equation (17), obtained by Doty, Zimm and Mark, relates the turbidity (actually, the extinction coefficient in cm. due to concentration fluctuations, which is the principal cause of heterogeneity) to the refractive index, n the concentration, c the refractive index increment dn/dc)] and the molecular weight, M, of the solute. 

The most frequent causes of heterogeneity in atmospheric corrosion are those related to water that may not be present on the surface in the form of a continuous film, but in a heterogeneous way, and those inherent to metallic materials underneath the water layer. 

Bovine serum albumin (Spencer and King, 1971 Salaman and Williamson, 1971 Wallevik, 1973, 1976) or human serum albumin (Ui, 1971) showed two or three major components in isoelectric focusing. The fact that heterogeneity persisted in defatted BSA after reversible denaturation in 6 M guanidine HCl or 6 M urea eliminated bound ligands as the only cause of heterogeneity. Also, the finding that serum albumin from six... 

In a homopolymer, the principal cause of heterogeneity will be the tacticity of the polymer, isotactic, syndiotactic and atactic polymers being expected to behave very differently, as outlined elsewhere in this volume. In cases where nominally atactic polymers consist of isotactic and syndiotactic sequences, the decay may in favourable simple cases be interpretable in terms of a summation of exponential decays of two kinetically distinct species. For a wide distribution of sites, a kinetic model recognising this heterogeneity may be more appropriate, although this yields information of limited usefulness. 

The scheme of dispersion effects displayed in engineering materials of different structures was considered and an analysis of the causes of their occurrence was performed in our work. The spectrum of structural noise is considered as an element of unified spectral characteristics, reflected interaction of the ultrasonic field with given parameters and heterogeneous medium... 

In general, the multiphasic heterogenous nature of the impact grade styrene-based polymers is the root cause of their opaque-turbid nature. In determining the transparency of the blends, size and the size-distribution pattern of the dispersed phase along with the refractive index difference between the continuous and the dispersed phases are two very important criterion [133]. 

Sample surface unrepresentative. Heterogeneity of the sample was given above as the cause of Class II deviations. The case in which heterogeneity causes one part of a surface to differ from another is clear enough it is often encountered with minerals. Here we wish to direct attention to cases where a surface, though uniform, differs in composition from the bulk of the sample. The cause may be an oxide film thick enough that composition differences between it and the bulk of the sample influence the analytical results. 

P-Lactamases are enzymes that hydrolyze the P-lactam ring of P-lactamantibiotics (penicillins, cephalosporins, monobactams and carbapenems). They are the most common cause of P-lactam resistance. Most enzymes use a serine residue in the active site that attacks the P-lactam-amid carbonyl group. The covalently formed acylester is then hydrolyzed to reactivate the P-lacta-mase and liberates the inactivated antibiotic. Metallo P-lactamases use Zn(II) bound water for hydrolysis of the P-lactam bond. P-Lactamases constitute a heterogeneous group of enzymes with differences in molecular structures, in substrate preferences and in the genetic localizations of the encoding gene (Table 1). 

Catalysts can be poisoned, or inactivated. A common cause of such poisoning is the adsorption of a molecule so tightly to the catalyst that it seals the surface of the catalyst against further reaction. Some heavy metals, especially lead, are very potent poisons for heterogeneous catalysts, which is why lead-free gasoline must be used in engines fitted with catalytic converters. The elimination of... 

Many liquid phase or heterogeneous solid—liquid or gas—liquid reactions result in gaseous products or byproducts. These products may be toxic (refer to Table 4.1) or flammable (refer to Table 5.1), or result in overpressurization of any sealed container or vessel. Unless pressure relief is provided, relatively small volumes of reactants — the presence of which may not be expected — may generate sufficient gas pressure to rupture a container. The causes of pressure build-up may be ... 

Equation (1.116) allows us to calculate the vertical component of the field in the upper half space when it is known at the earth s surface. Correspondingly, this transformation is called upward continuation and it is used to reduce an infiuence of geological noise, caused by heterogeneities with relatively small dimensions. 

One possible cause of Th isotope heterogeneity between minerals could be that they crystallized in a heterogeneous magma formed by incomplete mixing of two (or more)... 

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