40 research outputs found
Spin-phonon coupling in multiferroic RCrO (R-Y, Lu, Gd, Eu, Sm): A Raman study
Raman study on a select few orthochromites, RCrO (R = Y, Lu, Gd, Eu and
Sm) shows that the phonon behavior at TN in compounds with magnetic R-ion (Gd
and Sm) is remarkably different from that of non-magnetic R-ion (Y, Lu and Eu).
While anomalies in most of the observed phonon frequencies in all these
compounds may result from the distortion of CrO octahedra due to size
effect and magnetostriction arising from Cr-ordering, the anomalous behavior of
their linewidths observed at TN for the compounds with only magnetic R-ion
suggests spin-phonon coupling. The presence of spin-phonon coupling and the
anomalies in the low frequency modes related to R-ion motion in orthochromites
(R = Gd and Sm) support the suggestion that the coupling between 4f-3d moments
play important role in inducing switchable electric polarization.Comment: 6 pages (two column format), 7 figures; The updated version of the
manuscript can be found at Euro. Phys. Lett. 101, 17008 (2013
Effect of pressure on octahedral distortions in RCrO3 (R = Lu, Tb, Gd, Eu, Sm): The role of R-ion size and its implications
The effect of rare-earth ion size on the octahedral distortions in rare-earth
chromites (RCrO3, R = Lu, Tb, Gd, Eu, Sm) crystallizing in the orthorhombic
structure has been studied using Raman scattering and synchrotron powder x-ray
diffraction up to 20 GPa. From our studies on RCrO3 we found that the
octahedral tilts (distortions) increase with pressure. This is contrary to the
earlier report which suggests that in LaCrO3, the distortions decrease with
pressure leading to a more ordered phase at high pressure. Here we observe that
the rate of increase in distortion decreases with the increase in R-ion radii.
This occurs due to the reduction in the compression of RO12 polyhedra with a
corresponding increase in the compression of the CrO6 octahedra with increasing
R-ion radii. From the Raman studies, we predict a critical R-ion radii, above
which we expect the distortions in RCrO3 to reduce with increasing pressure
leading to what is observed in the case of LaCrO3. These Raman results are
consistent with our pressure dependent structural studies on RCrO3 (R = Gd, Eu,
Sm). Also, our results suggest that the pressure dependence of N\'eel
temperature, TNCr, (where the Cr3+ spin orders) in RCrO3 is mostly affected by
the compressions of Cr-O bonds rather than the alteration of octahedral tilts.Comment: 17 pages, 8 figures This manuscript has been published in Material
Research Expres
Influence of lattice distortion on the Curie temperature and spin-phonon coupling in LaMnCoO
Two distinct ferromagnetic phases of LaMnCoO having
monoclinic structure with distinct physical properties have been studied. The
ferromagnetic ordering temperature is found to be different
for both the phases. The origin of such contrasting characteristics is assigned
to the changes in the distance(s) and angle(s) between Mn - O - Co resulting
from distortions observed from neutron diffraction studies. Investigations on
the temperature dependent Raman spectroscopy provide evidence for such
structural characteristics, which affects the exchange interaction. The
difference in B-site ordering which is evident from the neutron diffraction is
also responsible for the difference in . Raman scattering
suggests the presence of spin-phonon coupling for both the phases around the
. Electrical transport properties of both the phases have been
investigated based on the lattice distortion.Comment: 9 figure
Alpha-1 antitrypsin deficiency impairs lung antibacterial immunity in mice
Alpha-1 antitrypsin (AAT) is a major inhibitor of serine proteases in mammals. Therefore, its deficiency leads to protease-antiprotease imbalance and a risk for developing lung emphysema. Although therapy with human plasma-purified AAT attenuates AAT deficiency-related emphysema, its impact on lung antibacterial immunity is poorly defined. Here, we examined the effect of AAT therapy on lung protective immunity in AAT-deficient (KO) mice challenged with Streptococcus pneumoniae. AAT-KO mice were highly susceptible to S. pneumoniae, as determined by severe lobar pneumonia and early mortality. Mechanistically, we found that neutrophil-derived elastase (NE) degraded the opsonophagocytically important collectins, surfactant protein A (SP-A) and D (SP-D), which was accompanied by significantly impaired lung bacterial clearance in S. pneumoniae-infected AAT-KO mice. Treatment of S. pneumoniae-infected AAT-KO mice with human AAT protected SP-A and SP-D from NE-mediated degradation and corrected the pulmonary pathology observed in these mice. Likewise, treatment with Sivelestat, a specific inhibitor of NE, also protected collectins from degradation and significantly decreased bacterial loads in S. pneumoniae-infected AAT-KO mice. Our findings show that NE is responsible for the degradation of lung SP-A and SP-D in AAT-KO mice affecting lung protective immunity in AAT deficiency
Loss of Serpina1 in Mice Leads to Altered Gene Expression in Inflammatory and Metabolic Pathways
The SERPINA1 gene encodes alpha1-antitrypsin (AAT), an acute phase glycoprotein and serine protease inhibitor that is mainly (80-90%) produced in the liver. Point mutations in the SERPINA1 gene can lead to the misfolding, intracellular accumulation, and deficiency of circulating AAT protein, increasing the risk of developing chronic liver diseases or chronic obstructive pulmonary disease. Currently, siRNA technology can knock down the SERPINA1 gene and limit defective AAT production. How this latter affects other liver genes is unknown. Livers were taken from age- and sex-matched C57BL/6 wild-type (WT) and Serpina1 knockout mice (KO) aged from 8 to 14 weeks, all lacking the five serpin A1a-e paralogues. Total RNA was isolated and RNA sequencing, and transcriptome analysis was performed. The knockout of the Serpina1 gene in mice changed inflammatory, lipid metabolism, and cholesterol metabolism-related gene expression in the liver. Independent single-cell sequencing data of WT mice verified the involvement of Serpina1 in cholesterol metabolism. Our results from mice livers suggested that designing therapeutic strategies for the knockout of the SERPINA1 gene in humans must account for potential perturbations of key metabolic pathways and consequent mitigation of side effects.RNA sequencing was supported by the grant ISCIII-AESI PI20CIII/00015.S
Exploring the Anti-inflammatory and Anti-cancer compounds from the leaves of Acalypha indica
Abstract: Acalypha indica (Euphorbiaceae) is commonly known as Indian Copperleaf and India
Performance Evaluation of Cloud Database Security Algorithms
Cloud computing is a group of servers providing the on demand computing services to the users on rental basis. One of the services providing by the cloud is Data Storage as a Service. In Data Storage as a Service user will outsource their sensitive data to cloud storage environment, where the users data will be stored and whenever user needs data, they will access from the cloud storage from anywhere and anytime using any device connected to the internet. One of the critical issues in this is data security. When user outsources their sensitive data to cloud vendor, the cloud vendor may leak the user’s sensitive data to third persons because vendor is not a trusted party. To overcome these problems there are many authors suggested different security algorithms. In this research we studied and evaluating the performances of those security algorithms and proposing a better solution, which provides best security to data stored in cloud databases
Qualitative Study on production of Methyl ester (Biodiesel) from Castor oil and Nannochloropsis
Biodiesel is evolving to be one of the most employed biofuels for partial replacement of petroleum-based diesel fuel. The most widely used feed stocks for biodiesel production are vegetable oils. But beside this traditional feedstock, microalgae is also of growing interest as a potential feedstock for biodiesel production due to its high lipid content when cultured under certain environment. In this work, biodiesel has been produced from Castor oil and Nannochloropsis Salina. The lipid content from Nannochloropsishas been extracted and converted into methyl ester using Soxhlet extraction (using two different solvents- n-hexane and chloroform and methanol mixture) followed by transesterification and using microwave assisted in-situ transesterification. The result shows that microwave irradiation has positive effect on lipid extraction from microalgae compared to traditional energy intensive Soxhlet extraction method. Although the microwave assisted in-situ transesterification is proved to be more effective for rupturing the rigid cell structure, the scalability of this process may be a challenge for large scale lipid extraction setup. The fatty acid composition of both the biodiesel sample was determined by Gas Chromatography. Results demonstrated that the COME (Castor oil methyl ester) is a better choice for diesel blending than Nannochloropsis Salina methyl ester
Combinatorial crystal synthesis of ternary solids based on 2-methylresorcinol
Cocrystallization experiments of 2-methylresorcinol with several N-bases were performed to identify selective and preferred crystallization routes in relevant structural landscapes. These preferred supramolecular synthon-based crystallization routes were further enhanced by using carefully chosen coformer combinations to synthesize stoichiometric ternary solids. The exercise consists of modular selection and amplification of supramolecular synthons from single through two-to three-component molecular solids, and is equivalent to solid state combinatorial synthesis