the acute ecotoxicity of a set of mixture samples (washing powders, wastes, fuel extracts etc.) was assessed using four acute ecotoxicity assays with aquatic organisms (daphnia magna, poecilia reticulata, artemia salina and desmodesmus subspicatus). the experimental concentration-response curves were fitted by seven two-parameter sigmoid equations using non-linear regression. the regression pe...

this study was carried out to determine regression equations for prediction of apparent metabolizable energy corrected by nitrogen (amen) using 11 barley cultivar (valfajr, karon, bahman, aras, dasht, afzal, zarjo, kavir, reihani, makui and yousef) the seeds obtain from alborz province, iran. all of the cultivar were analyzed based on proximate analysis, starch, ndf and adf. result showed that ...

the kinetics of zn sorption by ten calcareous soils of iran were measured and fitted to several equations (zero-, first-, second-, third-order, parabolic diffusion, simple elovich, and exponential equations). two initial concentrations of zinc i.e. 20 and 80 mg zn l-1 were used and observations were carried out for 100 hours. the time required to reach the near equilibrium state was about 24 ho...

Engel curves are often estimated within a linear, or at least approximately linear system of equations. However, Engel curves are required to lie on or within the unit interval, while summing to unity. These restrictions are not easily accommodated within a linear system. Therefore, we apply the fractional multinomial logit model in our estimation of expenditure shares, because it more readily ...

     Salt crystallization is one of the most powerful weathering agents that may cause a rapid change in the mechanical properties of stones, and thus limit their durability. Consequently, determining the mechanical properties of stones due to salt crystallization is important for natural building stones used in marine environmental and mild climatic conditions, which expose excessive salt crys...