Specific heat and magnetocaloric effect in Pr1-xAgxMnO3 manganites

The magnetocaloric effect in alternating magnetic fields has been investigated in Pr1-xAgxMnO3 manganites with x=0.05-0.25. The stepwise reversal of the sign of the magnetocaloric effect has been revealed in a weakly doped sample (x=0.05) at low temperatures (~80 K). This reversal is attributed to the coexistence of the ferromagnetic and canted antiferromagnetic phases with different critical temperatures.Comment: 4 pages, 4 figure

Institutional Trust and Cognitive Motivation toward Water Conservation in the Face of an Environmental Disaster

The agricultural sector in general, and in Iran in particular, is a major consumer of water and now finds itself under significant pressure due to water deficiency. This study used the Protection Motivation Theory to detect reasons for the imprudent consumption of water in Iran and to further its conservation. The Theory was extended for particular application to a seriously affected water basin, the Urmia Lake Basin in Northwest Iran. The factors governing water-saving intention among farmers in the Basin were investigated. Three hundred farmers were selected through a multi-stage, clustered, random sampling method. The results of structural equation modeling illustrated that while the original model variables accounted for 58 of the variance in water-saving intention, this rate increased to 63 in the extended model when institutional trust was used as a variable. Whereas response efficacy showed itself to be the strongest determinant of water-saving intention, all factors except perceived severity were significant in both models. Furthermore, the results of a multi-group analysis revealed that the intention to adopt water conservation measures is commensurate with the distance from the water resource and proximity to the (drying) lake. The findings of the study are expected to provide important information for policymakers looking to tailor policies to work in extreme water deficiency cases like the Urmia Lake Basin

Evolution of microstructural and mechanical properties of nanocrystalline Co2FeAl Heusler alloy prepared by mechanical alloying

Mechanical alloying (MA) has been used to fabricate the Co2FeAl Heusler alloy with a nanocrystalline structure. The formation mechanism of the alloy has been investigated. Rietveld analysis showed that all samples that were milled for more than 15 hours had an L21 structure with a space group of Fm3m. The crystallite size and internal strain of the samples were calculated using the Williamson-Hall equation. With mechanical alloying of up to 20 hours the crystallite size of Co2FeAl increased, after which the crystallite size started to decrease. In contrast, internal strain first decreased during the process and then increased with the increase of milling time. The powder obtained after 20 hours of MA was split into three parts and separately annealed at 300, 500 and 700 oC for 5 hours. A considerable increase was observed in the hardness value of powder particles with the increase of annealing temperature up to 500 oC. However, the hardness value of the sample annealed at 700 oC decreased. It seems that this feature is related to parameters such as increase of crystallite size, enhancement of lattice ordering, change in density of defects and impurities and nonstoichiometric effects