223 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
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
Evaluating mechanism and severity of injuries among trauma patients admitted to Sina Hospital, the National Trauma Registry of Iran
Purpose: Injuries are one of the leading causes of death and lead to a high social and financial burden. Injury patterns can vary significantly among different age groups and body regions. This study aimed to evaluate the relationship between mechanism of injury, patient comorbidities and severity of injuries. Methods: The study included trauma patients from July 2016 to June 2018, who were admitted to Sina Hospital, Tehran, Iran. The inclusion criteria were all injured patients who had at least one of the following: hospital length of stay more than 24 h, death in hospital, and transfer from the intensive care unit of another hospital. Data collection was performed using the National Trauma Registry of Iran minimum dataset. Results: The most common injury mechanism was road traffic injuries (49.0), followed by falls (25.5). The mean age of those who fell was significantly higher in comparison with other mechanisms (p < 0.001). Severe extremity injuries occurred more often in the fall group than in the vehicle collision group (69.0 vs. 43.5, p < 0.001). Moreover, cases of severe multiple trauma were higher amongst vehicle collisions than injuries caused by falls (27.8 vs. 12.9, p = 0.003). Conclusion: Comparing falls with motor vehicle collisions, patients who fell were older and sustained more extremity injuries. Patients injured by motor vehicle collision were more likely to have sustained multiple trauma than those presenting with falls. Recognition of the relationship between mechanisms and consequences of injuries may lead to more effective interventions. © 2021 Chinese Medical Associatio
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