22,391 research outputs found
Structural Basis for the Anomalously Low Spontaneous Polarisation Values of the Polar Phase of Sr1-xCaxTiO3 (x=0.02, 0.04): Evidence for a Ferrielectric Ordering
Full pattern Le-Bail refinement using x-ray powder diffraction profiles of
Sr1-xCaxTiO3 for x=0.02, 0.04 in the temperature range 12 to 300 K reveals
anomalies in the unit cell parameters at 170, 225 K due to an
antiferrodistortive (cubic to tetragonal I4/mcm) phase transition and at ~32,
~34 K due to a transition to a polar phase (tetragonal I4/mcm to orthorhombic
Ic2m), respectively. The lower transition temperatures obtained by us are in
excellent agreement with those reported on the basis of the dielectric studies
by Bednorz and Muller, [10] who attributed these to ferroelectric transition.
Rietveld analysis of the diffraction profiles of the polar phase reveals
off-centre displacements of both Sr2+/Ca2+ and Ti4+ ions in the X-Y plane along
pseudocubic directions, in agreement with the experimentally reported
direction of easy polarization by Bednorz and Muller, but the resulting dipole
moments are shown to be ferrielectrically coupled in the neighbouring (001)
planes along the [001] direction leading to anomalously low values of the
spontaneous polarization at 12K.Comment: 5 pages, 4 figures and 1 tabl
Stretching of a single-stranded DNA: Evidence for structural transition
Recent experiments have shown that the force-extension (F-x) curve for
single-stranded DNA (ssDNA) consisting only of adenine [poly(dA)] is
significantly different from thymine [poly(dT)]. Here, we show that the base
stacking interaction is not sufficient to describe the F-x curves as seen in
the experiments. A reduction in the reaction co-ordinate arising from the
formation of helix at low forces and an increase in the distance between
consecutive phosphates of unstacked bases in the stretched state at high force
in the proposed model, qualitatively reproduces the experimentally observed
features. The multi-step plateau in the F-x curve is a signature of structural
change in ssDNA.Comment: 10 pages, 4 figure
Mutual Perception and Relational Strategies of Hindus and Muslims in India
The present study examines mutual perception and relational strategies of the Hindu and Muslim groups in the cultural context of India by focusing on religion-based “othering.” A sample of 264 participants belonging to Hindu and Muslim groups was studied in Varanasi City. An instrument developed and used in an international project was adapted and given to participants (age range 20–60 years) for measuring their relational strategies, mutual perceptions and perceived discriminations. The findings revealed the ‘Coexistence’ relational strategy to be strongly placed in both Muslim and Hindu participants. Both ‘Integration’ and ‘Assimilation’ strategies were stronger in Muslim participants than in Hindu participants. Hindus preferred the ‘Separation’ strategy, perceived greater discrimination and held less positive views of Muslims. The findings are discussed along with their implications for dealing with the problem of Hindu-Muslim relationships in India
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