The inhibition effect of the grape pomace extract during the early stage of steel corrosion under adsorbed thin electrolyte layers was investigated. The present study was carried out to identify the components present in the 2-propanol grape pomace extract by GC-MS analysis. Gravimetric, electrochemical impedance spectroscopy, potentiodynamic polarization, scanning electron microscopy, and FTIR techniques were used to study the corrosion inhibitive. Polarization measurements have indicated that these green inhibitors acted through mixed type inhibition. SEM studies have evidenced the formation of a protective film over metal surface while FTIR supported by molecular modelling has proved that this shielding effect was caused by aldehydes particularly 2-phenylacetaldehyde and 3,7-dimethylocta-2,6-dienal.

The hyper-Wiener index was recently introduced by Randic. The original definition given by Randié can be used for acyclic structures only. In this paper the definition of Randic was extended in two different fashions so as to be applicable for any connected structure. The formula provides an easy method to calculate the hyper-Wiener index for any graph.

Particularly for structure−property correlations there are many chemical graph-theoretic indices, one of which is Wiener's “path number”. Because Wiener's original work focused on acyclic structures, one can imagine different ways of extending it to cycle-containing structures, several of which are noted here. Many of these different formulas in fact yield like numerical values for general connected graphsthat is, different formulas sometimes correspond to the same graph invariant. Indeed it is found that there are two “dominant” classes of formulas each corresponding to one of two distinct invariants. Extensions to sequences of invariants (with the Wiener index the first member) are more often found to give distinct sequences. Further a powerful vector-space theoretic view for characterizing and for comparing different sequences is described. This is illustrated for a collection of eight sequences in application to a set of molecular graph structures (corresponding to the octanes). Another type of extension is to generate a sequence or partially ordered set of graph invariants for which the Wiener index is the natural first member of this set. Certain such sets of invariants (corresponding to contributions from different types of subgraphs) are noted to be “complete” (or form a basis) in the sense that any invariant can be faithfully linearly expanded in terms of the members of the set.

ABSTRACT:The distance matrix D, the resistance-distance matrix , the related quotient matrices D/ and /D and the corresponding distance-related and resistance-distance-related descriptors: the Wiener index W, the Balaban indices J and J , the Kirchhoff index Kf, the Wiener-sum index WS, and Kirchhoff-sum index KfS are presented. A simple algorithm for computing the resistance-distance matrix is outlined. The distance-related and the resistance-distance-related indices are used to study cyclicity in four classes of polycyclic graphs: five-vertex graphs containing a five-cycle and Schlegel graphs representing platonic solids, buckminsterfullerene isomers and C 70 isomers. Among the considered indices only the Kirchhoff index correctly ranks according to their cyclicity, the Schlegel graphs for platonic solids, C 60 isomers, and C 70 isomers. The Kirchhoff index further produces the reverse order of five-vertex graphs containing a five-cycle (which could be simply altered to the correct order by adding a minus sign to the Kirchhoff indices for these graphs).

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of Abstract-Interaction of corrosion inhibitors with metal surfaces in acidic solutions was modelled by using a polynomial model based on the Langmuir adsorption isotherm. The curve-fitting procedure yielded a regression equation with a multiple correlation coeficient equal to 0.982. c: 1997 Elsevier Science Ltd

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