Ion-matrix interactions

Coordination, localization and stabilization of transition metal ions in zeolitic materials, apart from activation conditions, depend on the structure and composition of the zeolite matrix. To evaluate the extent of such a matrix effect Cu +ions are used as a metal ion probe in this work, and copper ion-matrix interaction in different zeolites and oxides has been studied by EPR and TPR. ... 

In the discussion so far we have considered the typical LEIS experiment only, i.e. large angles of incidence of exit relative to the surface plane. Under these conditions, in general, quantitative composition analysis is possible, because the ion-target interaction can be considered as a binary collision, because of the absence of matrix effects (see below). 

Integrins constitute a large family of a (3 heterodimeric cell surface, transmembrane proteins that interact with a large number of extracellular matrix components through a metal ion-dependent interaction. The term integrin reflects their function in integrating cell adhesion and migration with the cystoskeleton. 

Other substances that can accumulate within the body include poorly soluble particulates that are deposited in the alveolar region of the lungs, substances that bind irreversibly to endogenous proteins, and certain metals and ions that interact with the crystal matrix of bone. The properties of these substances are such that the body cannot readily remove them hence they gradually build up with successive exposures and the body burden can be maintained for long periods of time. 

Ions released into the matrix as the cement sets may interact with the organic part of the matrix. Metal ions, such as Ca + and AP+, may be chelated by car-boxylate groups, either on the polymer or on the tartaric acid additive. These have been considered in reasonable detail in the literature [230]. What has received far less attention is the possibility that fluoride ions might interact with carboxylic acid groups, either to modify the setting reaction or to become relatively securely anchored within the set cement. This possibility was raised in a review published in 1998 [230], but has not been followed up subsequently. It is based on the well-established observation that fluoride ion will form extremely strong hydrogen bonds with carboxylic acids in aqueous solution. They are of the type ... 

The most widely used mass spectrometric identification procedure is MALDI-Tof analysis of the entire peptide mixture. Gas-phase matrix interaction with peptide ions in MALDI-Tof results in singly charged ions, giving a mass profile that is highly characteristic of the protein from which the peptides are derived. These peptide masses (actually protonated peptide molecular ions, MH+) can be used to search databases (either protein or nucleic acid databases) to identify the proteins. The two most important factors in successfully identifying proteins by this approach are the number of matching peptide masses and the accuracy of the peptide mass determination. 

In this review results from two surface science methods are presented. Electron Spectroscopy for Chemical Analysis (ESCA or XPS) is a widely used method for the study of organic and polymeric surfaces, metal corrosion and passivation studies and metallization of polymers (la). However, one major accent of our work has been the development of complementary ion beam methods for polymer surface analysis. Of the techniques deriving from ion beam interactions, Secondary Ion Mass Spectrometry (SIMS), used as a surface analytical method, has many advantages over electron spectroscopies. Such benefits include superior elemental sensitivity with a ppm to ppb detection limit, the ability to detect molecular secondary ions which are directly related to the molecular structure, surface compositional sensitivity due in part to the matrix sensitivity of secondary emission, and mass spectrometric isotopic sensitivity. The major difficulties which limit routine analysis with SIMS include sample damage due to sputtering, a poor understanding of the relationship between matrix dependent secondary emission and molecular surface composition, and difficulty in obtaining reproducible, accurate quantitative molecular information. Thus, we have worked to overcome the limitations for quantitation, and the present work will report the results of these studies. 

Where is = counter-ion and solvent interaction ii = counter-ion and fixed ion interaction im = counter-ion and resin matrix interaction... 

The interactions between the charged fibres can be divided into ion non-specific and ion-specific parts. Ion non-specific part is the electrostatic interaction or repulsion between the ions and the charged matrix of the fibre wall. The strength of this interaction is assumed to depend only on the charge of the ionic species. The ion-specific part of the interaction contains the specific complexation of metal ions with the bound acidic groups and the adsorption of ions into polarised surfaces. By its very nature, the ion-specific interactions can be used to describe a more complex pattern of observed phenomena than non-specific interactions, but they also require a larger number of individually fitted numerical parameters in a model. 

Poly(ethylene oxide) is also used in nanocomposites which contain molybdenum disulfide or vanadium oxide. The inorganic filler and the organic matrix interact at a molecular level forming xerogels, which are nanocomposites with controlled ion mobility. ... 

CFractionation of aquatic humic substances by ion-exchance mechanisms s been limited severely by undesirable matrix interactions of the exchange medium. Hydrophobic matrix-exchange resins also interact with aquatic humic substances by hydrophobic effects (Abrams and Breslin, 1965) and hydrophilic matrix-exchange gels also interact with polyfunctional solutes by... 

With the use of this formula for the dipolar interaction, the matrix elements of the ion-dipole interaction in the basis of the nearly free wavefunctions are listed below. 

With the IRC-50-NaPSS system, the rigid matrix of the resin is resistant to the entry of solvent so that at equilibrium the concentration of counterions increases from 0.46 to 4.08M over the a range examined. At these resin-phase molarities it has been shown that the contribution of ion-solvent interaction to the deviation from ideal behavior of the counterions (II), while negligible at low concentration, is a factor to... 

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