The Padmakar-Ivan (PI) index is a Wiener-Szeged-like topological index which reflects certain structural features of organic molecules. The PI index of a graph G is the sum of all edges uv of G of the number of edges which are not equidistant from the vertices u and v. In this paper we obtain the second and third extremals of catacondensed hexagonal systems with respect to the PI index.

Abstract The Ciliwung River receives loads from various sources of pollution along the border, both agricultural waste, industrial and domestic waste. wastes that enter river cause a decrease in water quality. This study aims to determine quality status Jakarta segment based on Pollution Index (PI) Pesce-Wunderlin Water Quality (WQI). Monitoring was carried out February-September 2021 at 18 obs...

introduction: among the environmental pollutions, noise is very important for its physiological  and psychological effects on human. traffic noise is one of the most important pollutants and the  hospitals  are  one  of  the  critical  places  regarding  this  type  of  noise.  for  these  reasons,  in  the  summer  of  1382,  the  traffic  noise  of  mashhad  main  streets  around  the  hospit...

BACKGROUND Traffic-related air pollution has been associated to a range of adverse health impacts, including decreased heart rate variability (HRV). The association between traffic-related pollution and HRV, however, has varied by traffic-related or HRV marker as well as by study, suggesting the need for a more comprehensive and integrative approach to examining air pollution-mediated biologica...

The uncontrollable population growth is reaching Benin's rivers, especially the coastal lagoon, raising then thorny problem of pollution, which considerably accentuated by malevolent behavior populations. aim this paper to characterize degree contamination water and sediments lagoon in heavy metals (Cd, Cr, Zn, Cu, Pb Fe) through dosage with molecular absorption spectrophotometer type DR 3900. ...

Over the last few decades, Anzali wetland has been at risk of pollutants, especially from heavy metals. The present research analyzes some physical and chemical properties and heavy metals concentration in 27 points in nine stations of Anzali wetland. The samples of each station have been mixed, acidic digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The mean con...

in this survey article a brief account on the development of padmakar-ivan (pi) index in thatapplications of padmakar-ivan (pi) index in the fascinating field of nano-technology arediscussed.

The Padmakar-Ivan (PI) index of a graph G is the sum over all edges uv of G of the number of edges which are not equidistant from u and v. In this paper, the notion of vertex PI index of a graph is introduced. We apply this notion to compute an exact expression for the PI index of Cartesian product of graphs. This extends a result by Klavzar [On the PI index: PI-partitions and Cartesian product...