The vertex Padmakar-Ivan (PIv) index of a graph G was introduced as the sum over all edges e = uv of G of the number of vertices which are not equidistant to the vertices u and v. In this paper we provide an analogue to the results of T. Mansour and M. Schork [The PI index of bridge and chain graphs, MATCH Commun. Math. Comput. Chem. 61 (2009) 723-734]. Two efficient formulas for calculating th...

The concentrations of Cu, Zn, As, Pb, Cr, and Cd in soil were analyzed a mining area the Inner Mongolia Autonomous Region, China. average metal samples 204.07 mg/kg, 88.15 14.47 mg/kg 88.52 56.45 0.235 respectively. Based on evaluation standards, background values heavy metals, multiple pollution assessment indices, such as single factor index (Pi), geological accumulation (Igeo), Nemerow (Pn),...

twenty water samples from a river system in southern caspian sea basin werecollected and analyzed for physicochemical parameters and metals (cu, zn, as, cd, pb, ni andmn). in order to evaluate the risk potential of metal pollution in river water, use of two indicesnamely heavy metal pollution index (hpi) and contamination index (cd) accompanied by clusteranalysis was taken in to consideration. ...

Exposure to fine particles can cause various diseases, and an easily accessible method to monitor the particles can help raise public awareness and reduce harmful exposures. Here we report a method to estimate PM air pollution based on analysis of a large number of outdoor images available for Beijing, Shanghai (China) and Phoenix (US). Six image features were extracted from the images, which w...

The British Petroleum Deepwater Horizon Oil Spill in the Gulf of Mexico was the biggest oil spill in US history. To assess the impact of the oil spill on the saltmarsh plant community, we examined Advanced Visible Infrared Imaging Spectrometer (AVIRIS) data flown over Barataria Bay, Louisiana in September 2010 and August 2011. Oil contamination was mapped using oil absorption features in pixel ...

pollution of water and soils by heavy metals is an emerging problem in industrialized countries.the present study was conducted to investigate the heavy metals concentration in water and sedimentsamples from ship breaking sites of sitakunda to assess the potential ecological risk posed by heavy metalusing different methods. heavy metals concentration was analyzed by atomic absorption spectrosco...

in this paper some upper and lower bounds for the greatest eigenvalues of the pi and vertex pimatrices of a graph g are obtained. those graphs for which these bounds are best possible arecharacterized.

background and aims: air pollution is one of the health problems worldwide. previous epidemiological studies have investigated the impacts of air pollution on respiratory and cardiovascular diseases. the aim of this study was to determine the associations between air pollution levels and different health indicators among world countries. methods: this ecological study was performed in 2013 by u...