Specific Type Of Interaction Research Articles

Vibrational spectroscopic study of the interaction of metal ions with diethyl phosphate, a model for biological systems

We have studied, using Raman and infrared spectroscopy, the interaction of various monovalent, divalent, and trivalent metal cations with the [Formula: see text] group of diethyl phosphate in aqueous solution, at metal: phosphate ratios ranging from 1:40 to 6:1. The results show that the metal cations interact with the phosphate groups in various ways and to different extents. Spectral characteristics for some specific types of interactions are presented, namely, for direct metal binding by one of the oxygen atoms in the [Formula: see text] group, the formation of water-separated ion pairs, and non-specific electrostatic interactions.

Chemical, quasi‐chemical and perturbation theories for associating fluids

AbstractPure fluids and mixtures of species that hydrogen bond behave differently from systems that interact only through dispersion forces. The deviations from classical behavior often are sufficiently large that conventional equations of state and activity models cannot be used without the introduction of large, condition‐dependent empirical parameters. Consequently, three different classes of theories have been developed specifically to treat hydrogen‐bonding systems. The first is based on the assumption that when molecules hydrogen‐bond, they react to form new species and consequently is referred to as “chemical” theory. The second is based on lattice‐fluid theory that is used to describe different types of specific interactions and is known as “quasi‐chemical” theory. The last is based on the solution of integral equations using a potential function that mimics that of a hydrogen bond. It is shown here that these three approaches give essentially equivalent results. This allows one to relate the parameters in the perturbation theory to the equilibrium constant and hence greatly improves its utility for real systems. All three theories are compared with simulation data.

Experimental approaches for studying adhesion of microorganisms to solid substrata: applications and mass transport

Various experimental systems have been developed which enable the study of adhesion of microorganisms to solid substrata. These systems can be distinguished in flow systems and static systems; in addition, static systems can be divided into systems with relatively small and large suspension volumes. It will be argued that a proper knowledge of the mechanisms of mass transport is required in order to fully understand the deposition process, a fact that has been largely negelected in the current literature. Furthermore, it should be noted that the adsorption kinetics are different for systems with relatively small and large suspension volumes. Therefore two different but analogous phenomenological description of adhesion kinetics are presented. Finally, it is concluded that flow systemscan be advantageously employed over static systems whenever qunatitative results are required, and especially since correlations with data from other types of flow systems can be made more easily. Static systems may be preferred when specific types of interactions are studied.

Precise ultraviolet absorbance study of the interactions of amino acids and mononucleosides in aqueous solution.

The association constants of various amino acids or their derivatives (methyl esters, amides, etc.) with mononucleosides in aqueous solutions have been measured by using precise ultraviolet difference absorbance photometry. Some of the results are in agreement with those of the previous solubility experiments. The superiority of this ultraviolet absorbance method over the solubility experiments is that it can discriminate between stacking and hydrogen-bonding interactions. New types of specific interactions of some amino acids with nucleic acid bases by using a peptidyl carboxylate ion and another donor or acceptor in their side chains have been found using this technique.

Masculinity-femininity perceptions of job requirements and their relationship to job-sex stereotypes

Perceived sex appropriateness of the work situation is believed to constrain work opportunities, particularly for women. However, sex appropriateness may be defined either with respect to the entire job or with respect to the tasks which comprise the job. In this study sex appropriateness of job tasks was examined by obtaining subjective estimates of the masculinity-femininity of the job requirement dimensions defined by the Dictionary of Occupational Titles (DOT). Results indicate that interacting with things is perceived as masculine, interacting with people is perceived as feminine, and interacting with data is perceived as falling between the other two. There is less agreement on the masculinity-femininity of specific types of interactions with data, people, and things. Sex appropriateness of specific requirements was found to be only moderately associated with the DOT's assessment of the complexity of those requirements. Further, sex appropriateness of job requirements was not highly related to the job sextypes established by Shinar ( Shinar, E. H. Journal of Vocational Behavior, 1975 , 7, 99–110) and Krefting et al. ( Krefting, L. A., Berger, P. K., and Wallace, M. J. Jr. Journal of Vocational Behavior, 1978 , 13, 181–191). This suggests that sex appropriateness of a job and sex appropriateness of the tasks which comprise the job are distinct, separate concepts.

Linear interaction of electromagnetic waves in an inhomogeneous magnetoactive plasma

In this paper we discuss an asymptotic method which permits one to separate the initial equations for the fields in a plane stratified plasma into two independent systems, describing waves of differing types which propagate in a single direction. The coefficients of the derived equations remain regular at points of equality between the indices of refraction of normal waves, n1=n2. The equations are used to analyze a specific type of interaction which is of current interest in connection with research on low-frequency waves in the ionosphere. A solution is found by the method of the standard system which describes the field in the interaction region; outside this region, it turns into the geometric optics solution. Wave transformation coefficients are compared with those obtained earlier by the phase integral method.

Interaction of polynuclear aromatic hydrocarbons, 4-nitroquinoline 1-oxides, and various dyes with DNA.

AbstractBy using the flow dichroism method, in vitro interaction of the aromatic polynuclear hydrocarbons with calf thymus DNA was studied. A clear dichroism of the hydrocarbons which interacted with DNA was observed, showing a specific type of interaction. Hydrocarbons were classified into two groups, depending on whether the orientation is parallel or perpendicular to the direction of flow. 3,4‐Benzopyrene, pyrene, and phenanthrene belong to the first group, and the second group contains 20‐methylcholanthrene, tetracene, pentacene, and coronene. 4‐Nitroquinoline 1‐oxide (4‐NQO) and its derivatives have also been found to be oriented parallel to the planes of bases of DNA, and a distinct parallel was found between the amount of binding and carcinogenicity. Base specificity of binding of 4‐NQO with DNA‐was studied, and purines were suggested to be active sites of interaction. Actinomycin D, several acridine dyes, and methylene blue etc. were found to be oriented parallel to the planes of DNA bases, and in the cases of acridine dyes this finding does not contradict the intercalation mechanism proposed by Lerman.

THE CHEMICAL SHIFT OF AROMATIC ALKOXY GROUPS

The nuclear magnetic resonance (n.m.r.) spectra of 42 variously substituted anisoles and phenetoles have been obtained. The chemical shifts of the alkoxy hydrogens have been assembled in charts for ready use in interpreting the n.m.r. spectra of unknown compounds. For meta- and para-substituted anisoles, a reasonably good correlation has been shown to exist between the methyl resonance and the corresponding Hammett σ parameter. With anisole itself, a preferential solvent effect has been noticed which suggests a specific type of interaction between solute molecules.

Studies on Ion-exchange Resins. XIII. Selectivity Coefficients of Quaternary Base Anion-exchange Resins Toward Univalent Anions

Selectivity coefficients of a quaternary base ammonium anion-exchange resin toward a number of univalent anions have been measured. In some systems the selectivity coefficients varied little with composition, while in others a marked dependence was observed. Examples of the former included systems made up of various pairs of ions from Group A-halide, acetate, iodate and nitrate, or of pairs of ions from Group B-thiocyanate, perchlorate, di- and trichlolroacetate, trifluoroacetate, toluenesulfonate and naphthalenesulfonate. Examples of systems where the selectivity coefficient changed markedly were made up of an anion from Group A with one from Group B. These data were interpreted in terms of two postulated types of specific interactions (ion-pair formation) of these ions with those of the resin matrix. The ion-pairs of Group A were assumed to be randomly distributed in the resin phase, while those of Group B were assumed to occur in the form of “patches,” i.e., form clusters. The effect of temperature on the distribution coefficient was small; the concentration of the solution (when dilute) had a negligible effect upon the selectivity.