1,378 research outputs found
Temperature dependence of transport spin polarization in NdNi5 measured using Point Contact Andreev reflection
We report a study in which Point contact Andreev reflection (PCAR)
spectroscopy using superconducting Nb tip has been carried out on NdNi5, a
ferromagnet with a Curie temperature of TC~7.7K. The measurements were carried
out over a temperature range of 2-9K which spans across the ferromagnetic
transition temperature. From an analysis of the spectra, we show that (i) the
temperature dependence of the extracted value of transport spin polarization
closely follows the temperature dependence of the spontaneous magnetization;
(ii) the superconducting quasiparticle lifetime shows a large decrease close to
the Curie temperature of the ferromagnet. We attribute the latter to the
presence of strong ferromagnetic spin fluctuations in the ferromagnet close to
the ferromagnetic transition temperature.Comment: pdf file including figures-Typographical error and errors in
references correcte
Comparative Study between Rectangular Windows and Circular Windows Based Disparity-Map by Stereo Matching
Stereo matching is the basic problem to achieve human like vision capability to machines and robots. Stereo vision researches produced many local and global algorithms for stereo correspondence matching. There are two popular methods one is rectangular window-based cost aggregation another is circular window-based cost aggregation used for solving correspondence problem have attracted researches as it can be implemented in real time using parallel processors. In this paper we have done comparative study between rectangular windows and circular windows based disparity map by stereo matching. Motivated by human stereo vision, the technique uses to enhance the strategy of finding the best match to compute dense disparity map. Performance of the both method is efficient
Isothermal Titration Calorimetric Studies on the Interaction of the Major Bovine Seminal Plasma Protein, PDC-109 with Phospholipid Membranes
The interaction of the major bovine seminal plasma protein, PDC-109 with lipid membranes was investigated by isothermal titration calorimetry. Binding of the protein to model membranes made up of diacyl phospholipids was found to be endothermic, with positive values of binding enthalpy and entropy, and could be analyzed in terms of a single type of binding sites on the protein. Enthalpies and entropies for binding to diacylphosphatidylcholine membranes increased with increase in temperature, although a clear-cut linear dependence was not observed. The entropically driven binding process indicates that hydrophobic interactions play a major role in the overall binding process. Binding of PDC-109 with dimyristoylphosphatidylcholine membranes containing 25 mol% cholesterol showed an initial increase in the association constant as well as enthalpy and entropy of binding with increase in temperature, whereas the values decreased with further increase in temperature. The affinity of PDC-109 for phosphatidylcholine increased at higher pH, which is physiologically relevant in view of the basic nature of the seminal plasma. Binding of PDC-109 to Lyso-PC could be best analysed in terms of two types of binding interactions, a high affinity interaction with Lyso-PC micelles and a low-affinity interaction with the monomeric lipid. Enthalpy-entropy compensation was observed for the interaction of PDC-109 with phospholipid membranes, suggesting that water structure plays an important role in the binding process
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Engineering current density over 5 kA mm-2 at 4.2 K, 14 T in thick film REBCO tapes
We report on remarkably high in-field performance at 4.2 K achieved in >4 μm thick rare earth barium copper oxide (REBCO) samples with Zr addition. Two different samples have been measured independently at Lawrence Berkeley National Laboratory and the National High Magnetic Field Laboratory, achieving critical current densities (J ) of 12.21 MA cm and 12.32 MA cm at 4.2 K, 14 T (), respectively, which corresponds to equivalent critical current (I ) values of 2247 and 2119 A/4 mm. These I values are about two times higher than the best reported performance of REBCO tapes to date and more than five times higher than the commercial HTS tapes reported in a recent study. The measured J values, with a pinning force of ∼1.7 T N m are almost identical to the highest value reported for thin (∼1 μm thick) REBCO at the field and temperature, but extended to very thick (>4 μm) films. This results in an engineering current density (J ) above 5 kA mm at 4.2 K, 14 T, which is more than five times higher than Nb Sn and nearly four times higher than the highest reported value of all superconductors other than REBCO at this field and temperature. The reported results have been achieved by utilizing an advanced metal organic chemical vapor deposition system. This study demonstrates the remarkable level of in-field performance achievable with REBCO conductors at 4.2 K and strong potential for high-field magnet applications. c c c c e 3 -2 -2 -3 -
Droplet actuation induced by coalescence: experimental evidences and phenomenological modeling
This paper considers the interaction between two droplets placed on a
substrate in immediate vicinity. We show here that when the two droplets are of
different fluids and especially when one of the droplet is highly volatile, a
wealth of fascinating phenomena can be observed. In particular, the interaction
may result in the actuation of the droplet system, i.e. its displacement over a
finite length. In order to control this displacement, we consider droplets
confined on a hydrophilic stripe created by plasma-treating a PDMS substrate.
This controlled actuation opens up unexplored opportunities in the field of
microfluidics. In order to explain the observed actuation phenomenon, we
propose a simple phenomenological model based on Newton's second law and a
simple balance between the driving force arising from surface energy gradients
and the viscous resistive force. This simple model is able to reproduce
qualitatively and quantitatively the observed droplet dynamics
Class I methanol masers in low-mass star formation regions
Four Class I maser sources were detected at 44, 84, and 95 GHz toward
chemically rich outflows in the regions of low-mass star formation NGC 1333I4A,
NGC 1333I2A, HH25, and L1157. One more maser was found at 36 GHz toward a
similar outflow, NGC 2023. Flux densities of the newly detected masers are no
more than 18 Jy, being much lower than those of strong masers in regions of
high-mass star formation. The brightness temperatures of the strongest peaks in
NGC 1333I4A, HH25, and L1157 at 44 GHz are higher than 2000 K, whereas that of
the peak in NGC 1333I2A is only 176 K. However, rotational diagram analysis
showed that the latter source is also a maser. The main properties of the newly
detected masers are similar to those of Class I methanol masers in regions of
massive star formation. The former masers are likely to be an extension of the
latter maser population toward low luminosities of both the masers and the
corresponding YSOs.Comment: 5 pages, 1 figure, Proc. IAU Symp. 287 "Cosmic Masers: from OH to
H0". LSR velocities of the HH25 masers, which are presented in Table 1, are
correcte
Elemental nitrogen partitioning in dense interstellar clouds
Many chemical models of dense interstellar clouds predict that the majority
of gas-phase elemental nitrogen should be present as N2, with an abundance
approximately five orders of magnitude less than that of hydrogen. As a
homonuclear diatomic molecule, N2 is difficult to detect spectroscopically
through infrared or millimetre-wavelength transitions so its abundance is often
inferred indirectly through its reaction product N2H+. Two main formation
mechanisms each involving two radical-radical reactions are the source of N2 in
such environments. Here we report measurements of the low temperature rate
constants for one of these processes, the N + CN reaction down to 56 K. The
effect of the measured rate constants for this reaction and those recently
determined for two other reactions implicated in N2 formation are tested using
a gas-grain model employing a critically evaluated chemical network. We show
that the amount of interstellar nitrogen present as N2 depends on the
competition between its gas-phase formation and the depletion of atomic
nitrogen onto grains. As the reactions controlling N2 formation are
inefficient, we argue that N2 does not represent the main reservoir species for
interstellar nitrogen. Instead, elevated abundances of more labile forms of
nitrogen such as NH3 should be present on interstellar ices, promoting the
eventual formation of nitrogen-bearing organic molecules.Comment: Accepted for publication in the Proceedings of the National Academy
of Sciences of the United States of America - published online since June 11,
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