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RISS 인기검색어
- 검색키워드
- 저자 : M. Paydar (검색결과 3 건)
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Determination of Heavy Metal Content in Astacus leptodactylus caspicus of Anzali Wetland, Iran
Riahi, A.R.,Fazeli, M.Sh.,Paydar, M. The Ecological Society of Korea 2004 Journal of Ecology and Environment Vol.27 No.1
With attention to different human activities around Anzali wetland and introduction of different pollutants containing heavy metals into this water ecosystem and absorption and accumulation of heavy metals in shell and muscle of Astacus leptodactylus which is native benthose of Anzali wetland and enjoys food and economic importance; Sampling of waters and sediments from 18 stations and shell and muscle of Astacus leptodactylus from 5 stations had been conducted. After biometric evaluation of Astacus leptodactylus, the chemical analysis of the samples by using international and standard methods and then their heavy metals content was determined by Atomic Absorpotion Spectrophotometer (AAS), model P.U 9400 philips. Result of the analysis stated that; 1) The mean values of Cr, Zn, Pb, Ni, V in Anzali waters were 6.4, 184.5, 28.8, 28.9, 47.1 ($\mu$ gr/lit) respectively, which comparing to the international standards, is not suitable for drinking, but it can be used for agricultural and aquacultural purposes. Even though the concentration of heavy metals in sediments were high, there are in range of acceptable limit for aquatics organisms; 2) Comparatively, the concentration of heavy metals in shell and muscle of Astacus leptodactylus in Anzali wetland (Cr, Zn, Pb, Ni, V in shell were 3.48, 109.3, 14.13, 7.17, 36.2 and in muscle were 2.98, 131.98, 3.12, 4.77, 9.05 ppm respectively) were more than what is determined for Aras dam (in shell were 1.6, 224.3, 7.8, 7.6, 10.3 and in muscle were 1.4, 60.2, 0.45, 2.7, 4.4 mg/kgr respectively); 3) For all samples, concentration of heavy metals in all Astacus leptodactylus in Anzali wetland and Aras dam, was at tolerance level for human consumption; 4) There was no association with significant difference between weight and size of Astacus leptodactylus with absorption and accumulation of heavy metals; but there was a significant association between heavy metals content in water and in sediments, and in sediments, shell and muscle of Astacus leptodactylus in Anzali wetland.
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New Mathematical Stress Analysis in the Compressive Stage of the High-Pressure Torsion Process
S. Hadi,F. Rahimzadeh lotfabad,M. H. Paydar,R. Ebrahimi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8
In this study, a mathematical analysis based on the slab method is used to drive a formula to calculate the average hydrostaticpressure in the compressive stage of the HPT process. The analytical method used here leads to a relationship for describingthe average hydrostatic pressure as a function of the material shear strength, sample volume, cavity volume and force. Basedon the results obtained and by employing the Sturm’s theorem for polynomials, a general expression for the minimum forcerequired to start the deformation of the material under compressive force and creation of flash is developed. The analyticalresults were confirmed by carrying out some experiments by using commercial pure aluminum and copper as test materials. The experimental results showed good congruence with the analytical calculations. The most important outcome of thisanalysis is that with an appropriate selection of the sample volume, considering the capacity of the HPT press facility andthe proper choice of the die cavity volume, favorable average hydrostatic pressure, necessary for the purpose of applicationcan be achieved.
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