1,902 research outputs found
Magnetic and the magnetocaloric properties of Ce1-xRxFe2 and Ce(Fe1-xMx)2 compounds
We have studied selected rare earth doped and transition metal doped CeFe2
compounds by examining their structural, magnetic and magneto-thermal
properties. With substitution of Ce by 5 and 10% Gd and 10% Ho, the Curie
temperature can be tuned to the range of 267-318 K. Localization of Ce 4f
electronic state with rare earth substitutions is attributed for the
enhancement of Curie temperature. On the other hand, with Ga and Al
substitution at the Fe site, system undergoes paramagnetic to ferromagnetic
transition and then to an antiferromagnetic phase on cooling. The
magnetocaloric effect across the transitions has been studied from both
magnetization isotherms and heat capacity data. It is shown that by choosing
the appropriate dopant and its concentration, the magnetocaloric effect around
room temperature can be tuned.Comment: 13 pages, 6 figures, 2 table
Magnetism in Gallium doped CeFe_2: The martensitic scenario
Ce(Fe_{1-x}Ga_x)_2 compounds with x = 0, 0.01, 0.025 and 0.05 have been
investigated to unravel the effect of Ga on the magnetic state of CeFe_2. For
the first time, we find that the dynamic antiferromagnetic phase present in
CeFe_2 gets stabilized with Ga substitution. The hysteresis loops show that
while the compounds with x = 0 and 0.01 show normal behavior, the other two
show multiple magnetization steps across the antiferromagnetic-ferromagnetic
transition region. The virgin curve is found to lie outside the envelope curve
in these two compounds, similar to the observations made in Ru and Re
substituted CeFe_2 compounds. Temperature, sweep rate and time dependences of
the magnetization show that the compounds with x >=0.025 possess glassy
behavior at low temperatures. Various results obtained reveal that these two
compounds belong to the martensite family.Comment: 23 pages, 12 Figure
The C-terminal portion of the cleaved HT motif is necessary and sufficient to mediate export of proteins from the malaria parasite into its host cell
The malaria parasite exports proteins across its plasma membrane and a surrounding parasitophorous vacuole membrane, into its host erythrocyte. Most exported proteins contain a Host Targeting motif (HT motif) that targets them for export. In the parasite secretory pathway, the HT motif is cleaved by the protease plasmepsin V, but the role of the newly generated N-terminal sequence in protein export is unclear. Using a model protein that is cleaved by an exogenous viral protease, we show that the new N-terminal sequence, normally generated by plasmepsin V cleavage, is sufficient to target a protein for export, and that cleavage by plasmepsin V is not coupled directly to the transfer of a protein to the next component in the export pathway. Mutation of the fourth and fifth positions of the HT motif, as well as amino acids further downstream, block or affect the efficiency of protein export indicating that this region is necessary for efficient export. We also show that the fifth position of the HT motif is important for plasmepsin V cleavage. Our results indicate that plasmepsin V cleavage is required to generate a new N-terminal sequence that is necessary and sufficient to mediate protein export by the malaria parasite
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