A Note on General Third Geometric-arithmetic Index of Special Chemical Molecular Structures

In theoretical chemistry, the geometric-arithmetic indices were introduced to measure the stability of alkanes and the strain energy of cycloalkanes. In this note, we report the general third geometric-arithmetic index of unilateral polyomino chain and unilateral hexagonal chain. Also, the third geometric-arithmetic index of these chemical structures are presented.

The Correlation between the Zeroth-Order General Randic Indices and the π-Electronic Energies of Hexagonal Systems

A formula was proved for computing the zeroth-order general Randic index of a hexagonal system to explore the correlation between the zeroth-order general Randic index and the π-electronic energy of a hexagonal system.As a consequence,the extremal hexagonal systems with minimum or maximum zeroth-order general Randic index were completely characterized.Moreover,by using the least-square fit method and regression analysis,a new and close relation was found between the zeroth-order general Randic index and the π-electronic energy of a hexagonal system.So the zeroth-order general Randic index is a good measure of the π-electronic energies for benzenoid hydrocarbons.

Spatial distribution and ecological risk of heavy metals and their source apportionment in soils from a typical mining area, Inner Mongolia, China

Determining the distributions and sources of heavy metals in soils and assessing ecological risks are fundamental tasks in the control and management of pollution in mining areas.In this study,we selected 244 sampling sites around a typical lead(Pb)and zinc(Zn)mining area in eastern Inner Mongolia Autonomous Region of China and measured the content of six heavy metals,including cuprum(Cu),Zn,Pb,arsenic(As),cadmium(Cd),and chromium(Cr).The ecological risk of heavy metals was comprehensively evaluated using the Geo-accumulation index,Nemerow general pollution index,and potential ecological risk index.The heavy metals were traced using correlation analysis and principal component analysis.The results showed that the highest content of heavy metals was found in 0–5 cm soil layer in the study area.The average content of Zn,As,Pb,Cu,Cr,and Cd was 670,424,235,162,94,and 4 mg/kg,respectively,all exceeding the risk screening value of agricultural soil in China.The areas with high content of soil heavy metals were mainly distributed near the tailings pond.The study area was affected by a combination of multiple heavy metals,with Cd and As reaching severe pollution levels.The three pathways of exposure for carcinogenic and noncarcinogenic risks were ranked as inhalation>oral ingestion>dermal absorption.The heavy metals in the study area posed certain hazards to human health.Specifically,oral ingestion of these heavy metals carried carcinogenic risks for both children and adults,as well as noncarcinogenic risks for children.There were differences in the sources of different heavy metals.The tailings pond had a large impact on the accumulation of Cd,Zn,and Pb.The source of Cr was the soil parent material,the source of As was mainly the soil matrix,and the source of Cu was mainly the nearby Cu ore.The purpose of this study is to more accurately understand the extent,scope,and source of heavy metals pollution near a typical mining area,providing effective help to solve the problem of heavy metals pollution.

Super Edge-connectivity and Zeroth-order General Randi Index for -1≤α< 0

Let G be a connected graph with order n,minimum degree δ = δ（G） and edge-connectivity λ =λ（G）. A graph G is maximally edge-connected if λ = δ, and super edge-connected if every minimum edgecut consists of edges incident with a vertex of minimum degree. Define the zeroth-order general Randic index R_α-0（G） =Σ x∈V（G） d_G-α（x）, where dG（x） denotes the degree of the vertex x. In this paper, we present two sufficient conditions for graphs and triangle-free graphs to be super edge-connected in terms of the zeroth-order general Randic index for -1 ≤α 〈 0, respectively.

An Evaluation Method for Combustion Characteristics of Coal in Cement Industry

As the coal combustion behaviors are rather complex in the cement industry, the traditional assessment method cannot be directly applied to evaluate the quality of coal. Based on the thermal analysis tests of more than 80 kinds of anthracite and bituminous coal, three evaluation parameters, namely, burning intensity （I）, average capacity of heat release （Q）, and general burning index （S） are presented, combining with the consideration of application and calciner types in the cement industry. Taking these three parameters into consideration together is necessary. Experimental results show that the coal with higher S, lower I and higher Q can be rated as the best for the calciner in the cement industry. The quantitative indexes are given to evaluate the bituminous coal and anthracite in this paper. This new assessment method has implications for the design of calciner in the cement industry.

The effects of China’s VAT enlargement reform on the income redistribution of urban households

Using the 2007 input-output data and 2012 household survey data,this paper estimated the overall VAT and business tax burden of urban households in China on basis of the statutory tax rates,and then studied the redistribution effects of China’s recent VAT enlargement reform.We found that this reform improved the redistribution effects of VAT and business tax mainly through lowering the average tax burden and reducing the inequality within the bottom-income group,but the inequality among different income groups was not reduced considerably.Based on a simulation analysis,we finally suggested the reduction of applicable rates on necessities to improve the redistribution effects of VAT more effectively.