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&nbsp;vraj&nbsp;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