116 research outputs found
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
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