936 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
Ultrasonic pulse induced mechanoluminescence of europium doped strontium aluminate micro-crystals
When rare earth doped strontium aluminate micro-crystals are exposed to ultrasonic pulse, then mechanumnescence (ML) is induced. The intensity of ML is proportional to the power of ultrasonic pulse used for ML excitation. The ML in europium doped strontium aluminate micro-crystals can be understood on the basis of the piezoelectrically induced electron detrapping model. On the basis of the piezoelectrically-induced electron detrapping model, expressions are derived for the general kinetics of ML intensity, rise of ML intensity, peak ML intensity and decay of ML intensity, in which good agreement is found between the theoretical and experimental results. A linear relation between the ML intensity and the ultrasonic power can also be understood on the basis of the proposed theory. The present investigation shows that the ML can be used to detecting the presence of ultrasonic waves and also for the measurement of ultrasonic power. 
Energy level statistics of interacting trapped bosons
It is an well established fact that statistical properties of energy level
spectra are the most efficient tool to characterize nonintegrable quantum
systems. The study of statistical properties and spectral fluctuation in the
interacting many boson systems have developed a new interest in this direction.
Specially we are interested in the weakly interacting trapped bosons in the
context of Bose-Einstein condensation (BEC) as the energy spectrum shows a
transition from the collective to single particle nature with the increase in
the number of levels. However this has received less attention as it is
believed that the system may exhibit Poisson like fluctuations due to the
existence of external harmonic trap. Here we compute numerically the energy
levels of the zero-temperature many-boson systems which are weakly interacting
through the van der Waals potential and are in the 3D confined harmonic
potential. We study the nearest neighbour spacing distribution and the spectral
rigidity by unfolding the spectrum. It is found that increase in number of
energy levels for repulsive BEC induces a transition from a Wigner like form
displaying level repulsion to Poisson distribution for P(s). It does not follow
the GOE prediction. For repulsive interaction, the lower levels are correlated
and manifest level repulsion. For intermediate levels P (s) shows mixed
statistic which clearly signifies the existence of two energy scales: external
trap and interatomic interaction. Whereas for very high levels the trapping
potential dominates, genarating Poisson distribution. Comparison with
mean-field results for lower levels are also presented. For attractive BEC near
the critical point we observe the Shrielman like peak near s=0 which signifies
the presence of large number of quasi-degenerate states.Comment: 12 page
Preclinical evaluation of antihyperglycemic activity of Clerodendron infortunatum leaf against streptozotocin-induced diabetic rats
© The Author(s) 2011. This article is published with open access at Springerlink.com Introduction: Clerodendron infortunatum Linn. (Verbenaceae), commonly known as Bhant in Hindi, is a small shrub occurring throughout the plains of India, which is traditionally used for several medicinal purposes. The aim of the present stud
A Plasmodium falciparum Host-Targeting Motif Functions in Export during Blood Stage Infection of the Rodent Malarial Parasite Plasmodium berghei
Plasmodium falciparum (P. falciparum) secretes hundreds of proteins—including major virulence proteins—into the host erythrocyte. In order to reach the host cytoplasm, most P. falciparum proteins contain an N terminal host-targeting (HT) motif composed of 11 amino acids. In silico analyses have suggested that the HT motif is conserved throughout the Plasmodium species but experimental evidence only exists for P. falciparum. Here, we show that in the rodent malaria parasite Plasmodium berghei (P. berghei) a reporter-like green fluorescent protein expressed by the parasite can be exported to the erythrocyte cytoplasm in a HT-specific manner. This provides the first experimental proof that the HT motif can function as a signal for protein delivery to the erythrocyte across Plasmodium species. Further, it suggests that P. berghei may serve as a model for validation of P. falciparum secretome proteins. We also show that tubovesicular membranes extend from the vacuolar parasite into the erythrocyte cytoplasm and speculate that these structures may facilitate protein export to the erythrocyte
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