15,541 research outputs found
Enhancement of magnetoresistance in manganite multilayers
Magnanite multilayers have been fabricated using La0.67Ca0.33MnO3 as the
ferromagnetic layer and Pr0.7Ca0.3MnO3 and Nd0.5Ca0.5MnO3 as the spacer layers.
All the multilayers were grown on LaAlO3 (100) by pulse laser deposition. An
enhanced magnetoresistnace (defined (RH- R0)/R0) of more than 98% is observed
in these multilayers. Also a low field magnetoresistance of 41% at 5000 Oe is
observed in these multilayer films. The enhanced MR is attributed to the
induced double exchange in the spacer layer, which is giving rise to more
number of conducting carriers. This is compared by replacing the spacer layer
with LaMnO3 where Mn exists only in 3+ state and no enhancement is observed in
the La0.67Ca0.33MnO3 / LaMnO3 multilayers as double exchange mechanism can not
be induced by external magnetic fields.Comment: 13 pages, 5 Figure
Reviving Gujarat State Road Transport Corporation: An Agenda for Action
In this article, we examine in detail the reasons related to the declining operating and financial performance of Gujarat State Road Transport Corporation (GSRTC). The contribution of various environmental and governance issues related to the decline of GSRTC are identified. Based on the diagnosis, a detailed revival plan consisting of a set of actions to be undertaken by the management is proposed. The responsibilities of the government, the management, and the employees in implementing the revival plan are briefly discussed. This article concludes with set of strategic priorities that need to be examined by government in reviving GSTRC and other similar state-owned public utilities.
The effects of transients on photospheric and chromospheric power distributions
We have observed a quiet Sun region with the Swedish 1-meter Solar Telescope
(SST) equipped with CRISP Imaging SpectroPolarimeter. High-resolution,
high-cadence, H line scanning images were taken to observe different
layers of the solar atmosphere from the photosphere to upper chromosphere. We
study the distribution of power in different period-bands at different heights.
Power maps of the upper photosphere and the lower chromosphere show suppressed
power surrounding the magnetic-network elements, known as "magnetic shadows".
These also show enhanced power close to the photosphere, traditionally referred
to as "power halos". The interaction between acoustic waves and inclined
magnetic fields is generally believed to be responsible for these two effects.
In this study we explore if small-scale transients can influence the
distribution of power at different heights. We show that the presence of
transients, like mottles, Rapid Blueshifted Excursions (RBEs) and Rapid
Redshifted Excursions (RREs), can strongly influence the power-maps. The short
and finite lifetime of these events strongly affects all powermaps, potentially
influencing the observed power distribution. We show that Doppler-shifted
transients like RBEs and RREs that occur ubiquitously, can have a dominant
effect on the formation of the power halos in the quiet Sun. For magnetic
shadows, transients like mottles do not seem to have a significant effect in
the power suppression around 3 minutes and wave interaction may play a key role
here. Our high cadence observations reveal that flows, waves and shocks
manifest in presence of magnetic fields to form a non-linear
magnetohydrodynamic system.Comment: 11 pages, 11 Figures, 4 movies (will be available online in ApJ). ApJ
(accepted
Giant Meterwave Radio Telescope observations of an M2.8 flare: insights into the initiation of a flare-coronal mass ejection event
We present the first observations of a solar flare with the GMRT. An M2.8
flare observed at 1060 MHz with the GMRT on Nov 17 2001 was associated with a
prominence eruption observed at 17 GHz by the Nobeyama radioheliograph and the
initiation of a fast partial halo CME observed with the LASCO C2 coronograph.
Towards the start of the eruption, we find evidence for reconnection above the
prominence. Subsequently, we find evidence for rapid growth of a vertical
current sheet below the erupting arcade, which is accompanied by the flare and
prominence eruption.Comment: Accepted for publication in Solar Physic
Elasticity-mediated self-organization and colloidal interactions of solid spheres with tangential anchoring in a nematic liquid crystal
Using laser tweezers and fluorescence confocal polarizing microscopy, we
study colloidal interactions of solid microspheres in the nematic bulk caused
by elastic distortions around the particles with strong tangential surface
anchoring. The particles aggregate into chains directed at about 30 degrees to
the far field director and, at higher concentrations, form complex kinetically
trapped structures. We characterize the distance and angular dependencies of
the colloidal interaction forces.Comment: 6 pages, 5 figure
Removal of toxic metals from solution by leaf, stem and root phytomass of Quercus ilex L. (holly oak)
Increased consciousness for safeguarding the aqueous environment has prompted a search for alternative technologies for the removal of toxic metal ions from aqueous solutions. In this regard, a wide variety of biomass is being considered as adsorbents of heavy metals for treatment of industrial and domestic wastewaters as well as natural waters, including drinking water. In the present investigation, the potential of Quercus ilex phytomass from stem, leaf and root as an adsorbent of chromium (Cr), nickel (Ni), copper (Cu), cadmium (Cd) and lead (Pb) at ambient temperature was investigated. The metal uptake capacity of the root for different metals was found to be in the order: Ni>Cd>Pb>Cu>Cr; stem Ni>Pb>Cu>Cd>Cr; and leaf Ni>Cd>Cu>Pb>Cr. The highest amount adsorbed was Ni (root>leaf>stem). Data from this laboratory demonstrated that Ni is sequestered mostly in the roots, where concentrations can be as high as 428.4 ng/g dry wt., when 1-year-old seedlings were treated with Ni (2000 mg/l) in pot culture experiments, compared to 7.63 ng/g dry wt., control (garden and greenhouse soil) topsoil where Ni was present in trace amounts. This proves that the root biomass of Q. ilex has the capacity for complexing Ni. Cr exhibited the least adsorption values for all the three types of phytomass compared to other metals. The trend of adsorption of the phytomass was similar for Ni and Cd, i.e. root>leaf>stem. Desorption with 10 mM Na4 EDTA was effective (55-90%) and, hence, there exists the possibility of recycling the phytomass. The biosorption results of recycled phytomass suggest that the selected adsorbents are re-usable. The advantages and potential of the Q. ilex phytomass as a biofilter of toxic trace metals, the scope and need for enhancing the efficiency of the Q. ilex phytomass as an adsorbent of metals are presented.http://www.sciencedirect.com/science/article/B6VB5-40NFSK0-B/1/2e726350ef28f37aa6dd7fc8ababc91
Secreted proteins of normal and myc-ras oncogene transformed rat embryo fibroblasts
Quiescent cultures of rat embryo fibroblasts synthesize and secrete several proteins in response to mitogenic stimulation. Two of these proteins have been characterized in this study and the effect of oncogenic transformation on these proteins was monitored. A serum induced 48,000 protein was shown to be related to plasminogen activator inhibitor while another serum-induced protein of Mr 45,000 was found to be an inhibitor of DNA synthesis. Transformation of rat embryo fibroblasts with oncogenesmyc andras resulted in drastic reduction in the level of these proteins. The reduced levels of protease inhibitor may be responsible for the loss of anchorage dependence of the transformed cells. The DNA synthesis inhibitor protein may act as a negative growth regulator and reduced levels of this protein in myc-ras transformed cells may accelerate the proliferation of these cells
- …