188 research outputs found
Primary ovarian leiomyoma in a postmenopausal woman: a case report
Ovarian leiomyoma is a benign primary smooth muscle tumor. It is a small solid tumor commonly occurring in premenopausal women. Here we present a case of large ovarian leiomyoma in a postmenopausal woman
Teacher professional learning communities : a participatory resource creation approach to OER in Karnataka
The presentation focuses on research in open educational resources: the techno-social context such as ICT infrastructure; the pedagogical context as in teacher development; and socio-cultural context (building community), and how these are affected by teacher participation in, and creation of OER. It reviews a survey of teachers in Karnataka (India). The use of digital methods in OER adoption helped teachers to create resources in different formats, using different editors and tools learnt in the workshops, and also to share with peers over mailing lists. OER should be made available in local languages to be contextually relevant
Studies on the biology of the dog-whelk Nassastolata (Gmelin) of Portonovo waters
The morphology, anatomy and sex ratio of the mud snail Nassa stolata (Gmelin) were studied. The species, being a facultative omnivore. feeds mainly on dead animals and the digestive system is suited to this mode of feeding. The radula is of rachiglossate type and is well suited for tearing and rasping. The female reproductive system is more complicated than that of male- Studies on sex ratio clearly show the preponderance of males over females. The males mature at a size of 12.1 mm female at 12.5 mm
Electronic and Thermoelectric Properties of RuIn_{3-x}A_{x} (A = Sn, Zn)
Recently, we reported [M. Wagner et al., J. Mater. Res. 26, 1886 (2011)]
transport measurements on the semiconducting intermetallic system RuIn3 and its
substitution derivatives RuIn_{3-x}A_{x} (A = Sn, Zn). Higher values of the
thermoelectric figure of merit (zT = 0.45) compared to the parent compound were
achieved by chemical substitution. Here, using density functional theory based
calculations, we report on the microscopic picture behind the measured
phenomenon. We show in detail that the electronic structure of the substitution
variants of the intermetallic system RuIn_{3-x}A_{x} (A = Sn, Zn) changes in a
rigid-band like fashion. This behavior makes possible the fine tuning of the
substitution concentration to take advantage of the sharp peak-like features in
the density of states of the semiconducting parent compound. Trends in the
transport properties calculated using the semi-classical Boltzmann transport
equations within the constant scattering time approximation are in good
agreement with the former experimental results for RuIn_{3-x}Sn_{x}. Based on
the calculated thermopower for the p-doped systems, we reinvestigated the
Zn-substituted derivative and obtained ZnO-free RuIn_{3-x}Zn_{x}. The new
experimental results are consistent with the calculated trend in thermopower
and yield large zT value of 0.8.Comment: PRB Accepted, 11 pages, 10 figure
Interplay between superconductivity and magnetism in K-doped EuFe2As2
Superconductivity is found in 50% K-doped EuFe2As2 sample below 33 K. Our
results of electrical resistivity, magnetic susceptibility and 57Fe and 151Eu
Mossbauer spectroscopy provide clear evidence that the ordering of the Fe
moments observed at 190 K in undoped EuFe2As2 is completely suppressed in our
50% K doped sample, thus there is no coexistence between the Fe magnetic order
and the superconducting state. However, short range ordering of the Eu moments
is coexisting with the superconducting state below 15 K. A bump in the
susceptibility well below Tc as well as a slight broadening of the Fe Mossbauer
line below 15 K evidence an interplay between the Eu magnetism and the
superconducting state.Comment: 7 pages, 6 figure
Electronic signature of the vacancy ordering in NbO (Nb3O3)
We investigated the electronic structure of the vacancy-ordered 4d-transition
metal monoxide NbO (Nb3O3) using angle-integrated soft- and hard-x-ray
photoelectron spectroscopy as well as ultra-violet angle-resolved photoelectron
spectroscopy. We found that density-functional-based band structure
calculations can describe the spectral features accurately provided that
self-interaction effects are taken into account. In the angle-resolved spectra
we were able to identify the so-called vacancy band that characterizes the
ordering of the vacancies. This together with the band structure results
indicates the important role of the very large inter-Nb-4d hybridization for
the formation of the ordered vacancies and the high thermal stability of the
ordered structure of niobium monoxide
Magnetic Lattice Dynamics of the Oxygen-Free FeAs Pnictides: How Sensitive are Phonons to Magnetic Ordering?
To shed light on the role of magnetism on the superconducting mechanism of
the oxygen-free FeAs pnictides, we investigate the effect of magnetic ordering
on phonon dynamics in the low-temperature orthorhombic parent compounds, which
present a spin-density wave. The study covers both the 122 (AFe2As2; A=Ca, Sr,
Ba) and 1111 (AFeAsF; A=Ca, Sr) phases. We extend our recent work on the Ca
(122 and 1111) and Ba (122) cases by treating computationally and
experimentally the 122 and 1111 Sr compounds. The effect of magnetic ordering
is investigated through detailed non-magnetic and magnetic lattice dynamical
calculations. The comparison of the experimental and calculated phonon spectra
shows that the magnetic interactions/ordering have to be included in order to
reproduce well the measured density of states. This highlights a
spin-correlated phonon behavior which is more pronounced than the apparently
weak electron-phonon coupling estimated in these materials. Furthermore, there
is no noticeable difference between phonon spectra of the 122 Ba and Sr,
whereas there are substantial differences when comparing these to CaFe2As2
originating from different aspects of structure and bonding
Quantum Confinement
Quantum confinement is the spatial confinement of electron–hole pairs (excitons) in one or more dimensions within a material, and also electronic energy levels are discrete. It is due to the confinement of the electronic wave function to the physical dimensions of the particles. In this effect can be divided into three ways, 1D confinement (free carrier in a plane), quantum wells; 2D confinement (carriers are free to move down), quantum wire; and 3D confinement (carriers are confined in all directions), which are discussed in details. In addition the formation mechanism of exciton and quantum confinement behavior of strong, moderate, and weak confinement have been discussed below.MHRD-SPARC (ID: 890/2019) & UKIERI by the Governments of India and UK
Effect of hybridization on structural and magnetic properties of iron-based superconductors
We show that the strong hybridization between the iron 3d and the arsenic 4p
orbitals, in the newly discovered iron-based high-T superconductors,
leads to an explanation of certain experimental observations that are presently
not well understood. The existence of a lattice distortion, the smallness of
the Fe magnetic moment in the undoped systems, and the suppression of both the
lattice distortion and the magnetic order upon doping with fluorine, are all
shown to result from this hybridization.Comment: 4 pages, 2 figure
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