11,562 research outputs found
EuCo2P2: A Model Molecular-Field Helical Heisenberg Antiferromagnet
The metallic compound EuCo2P2 with the body-centered tetragonal ThCr2Si2
structure containing Eu spins 7/2 was previously shown from single-crystal
neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM)
structure below TN = 66.5 K with the helix axis along the c axis and with the
ordered moments aligned within the ab-plane. Here we report crystallography,
electrical resistivity, heat capacity, magnetization and magnetic
susceptibility measurements on single crystals of this compound. We demonstrate
that EuCo2P2 is a model molecular-field helical Heisenberg antiferromagnet from
comparisons of the anisotropic magnetic susceptibility chi, high-field
magnetization and magnetic heat capacity of EuCo2P2 single crystals at
temperature T < TN with the predictions of our recent formulation of molecular
field theory. Values of the Heisenberg exchange interactions between the Eu
spins are derived from the data. The low-T magnetic heat capacity ~ T^3 arising
from spin-wave excitations with no anisotropy gap is calculated and found to be
comparable to the lattice heat capacity. The density of states at the Fermi
energy of EuCo2P2 and the related compound BaCo2P2 are found from the heat
capacity data to be large, 10 and 16 states/eV per formula unit for EuCo2P2 and
BaCo2P2, respectively. These values are enhanced by a factor of ~2.5 above
those found from DFT electronic structure calculations for the two compounds.
The calculations also find ferromagnetic Eu-Eu exchange interactions within the
ab-plane and AFM interactions between nearest- and next-nearest planes, in
agreement with the MFT analysis of chi{ab}(T < TN).Comment: 20 pages, 17 figures, 3 tables, 46 references. This is an extended
replacement of arXiv:1512.02958 with an additional coautho
Characterization and photocatalytic study of tantalum oxide nanoparticles prepared by the hydrolysis of tantalum oxo-ethoxide Ta₈(μ₃-O)₂(μ-O)₈(μ-OEt)₆(OEt)₁₄
Ta-8(mu(3)-O)(2)(mu-O)(8)(mu-OEt)(6)(OEt)(14) (1) was obtained by the controlled hydrolysis of tantalum ethoxide Ta(OEt)(5) in the presence of ammonia. Compound 1 is considered as the intermediate building block in the sol-gel polymerization of Ta(OEt)(5). Further hydrolysis of compound 1 yielded nanoparticles of Ta2O5, which were characterized by various techniques such as TGA-DTA-DSC, UV-vis DRS, XRD, SEM, TEM, particle size analyzer (DLS) and the Brunauer-Emmett-Teller (BET) method. The band gap of the particles was calculated by using the Tauc plot. The photocatalytic activity of Ta2O5 nanoparticles was tested by the degradation of the organic dye rhodamine B
Multiwavelength Study of NGC 281 Region
We present a multiwavelength study of the NGC 281 complex which contains the
young cluster IC 1590 at the center, using deep wide-field optical UBVI_c
photometry, slitless spectroscopy along with archival data sets in the
near-infrared (NIR) and X-ray. The extent of IC 1590 is estimated to be ~6.5
pc. The cluster region shows a relatively small amount of differential
reddening. The majority of the identified young stellar objects (YSOs) are low
mass PMS stars having age <1-2 Myr and mass 0.5-3.5 M_\odot. The slope (\Gamma)
of the mass function for IC 1590, in the mass range 2 < M/M_\odot \le 54, is
found to be -1.11+-0.15. The slope of the K-band luminosity function
(0.37+-0.07) is similar to the average value (~0.4) reported for young
clusters. The distribution of gas and dust obtained from the IRAS, CO and radio
maps indicates clumpy structures around the central cluster. The radial
distribution of the young stellar objects, their ages, \Delta(H-K) NIR-excess,
and the fraction of classical T Tauri stars suggest triggered star formation at
the periphery of the cluster region. However, deeper optical, NIR and MIR
observations are needed to have a conclusive view of star formation scenario in
the region. The properties of the Class 0/I and Class II sources detected by
using the Spitzer mid-infrared observations indicate that a majority of the
Class II sources are X-ray emitting stars, whereas X-ray emission is absent
from the Class 0/I sources. The spatial distribution of Class 0/I and Class II
sources reveals the presence of three sub-clusters in the NGC 281 West region.Comment: 29 pages, 21 figures and 11 tables, Accepted for the publication in
PAS
A Survey on MRI Brain Image Segmentation Technique
One of the most dangerous disease occurring these days i.e. brain tumor can be detected by MRI images. Biomedical imaging and medical image processing that plays a vital role for MRI images has now become the most challenging field in engineering and technology. A detailed information about the anatomy can be showed through MRI images, that helps in monitoring the disease and is beneficial for the diagnosis as it consists of a high tissue contrast and have fewer artifacts. For tracking the disease and to proceed its treatment, MRI images plays a key role. It is having several advantages over other imaging techniques and is an important step for post-processing of medical images. However, having a large amount of data for manual analysis can sometimes proved to be an obstacle in the way of its effective use. In this paper, the introduction of image processing and the details of image segmentation techniques such as image preprocessing, feature extraction, image enhancement and classification of tumor processes, and how image segmentation can be applied to all Other available imaging modalities that are different from one another. This paper provides the survey on various methods used for image segmentation that have been applied for MRI images, that detects the tumor by segmenting the brain images into constituent parts. Also the advantages and disadvantages of Image segmentation is discussed using the various approaches of image segmentation of MRI brain images
Environmental Quality of the Boula-Nuasahi Chromite Mine Area in India
Chromite mining can create hostile conditions
for organisms in the surrounding environment. Overburden
soil and mine water samples were collected and analyzed
for their microbial diversity, nutrient content, and water
quality at the Boula-Nuasahi Mine. Most of the water
parameters that were measured exceed national/international
standards. The microbial population was low (soil:
45 ± 0.06 9 105 bacteria, 20 ± 0.03 9 105 fungus) and
the overburden soils have a low nutrient (N, P, K) content.
The metal ions were found to have leached to nearby
agriculture lands, making them less fertile for crop production.Overburden dumps and seepage water were found
to be the main sources of chromium pollution
A report of sample survey on births and deaths in agra district
The government of India has considered Agra to be made a ‘target free district'for MCH and family welfare programmes. For Intervention of this strategy, it is necessary to know the current trends of births, deaths and other parameters related to mother and child health, present study was undertaken in selected rural and urban slum areas of Agra district, covering total population of44,868. It was found that birth rate, death rate, infant mortality rate and maternal mortality rate was higher in rural area as compared to urban area. Maximum number of births were recorded during October and November and death rate vraj higher during November and December. Main causes of infact mortality ;were prematurity, low birth weight, diarrhoea and pnettmonie and that of maternal mortality were puerperal sepsis and haemorrhag
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