BVRI CCD photometric standards in the field of GRB 990123

The CCD magnitudes in Johnson $BV$ and Cousins $RI$ photometric passbands are determined for 18 stars in the field of GRB 990123. These measurements can be used in carrying out precise CCD photometry of the optical transient of GRB 990123 using differential photometric techniques during non--photometric sky conditions. A comparison with previous photometry indicates that the present photmetry is more precise.Comment: Tex file, 5 pages with 1 figure. Bull. Astron. Society India, Vol. 27 (accepted

GRB000301C with peculiar afterglow emission

The CCD magnitudes in Johnson V and Cousins R and I photometric passbands are determined for GRB 000301C afterglow starting ~ 1.5 day after the gamma-ray burst. In fact we provide the earliest optical observations for this burst. Light curves of the afterglow emissions in U, B, V, R, I, J and K' passbands are obtained by combining the present measurements with the published data. Flux decay shows a very uncommon variation relative to other well observed GRBs. Overall, there is a steepening of the optical and near-infrared flux decay caused by a geometric and sideways expanding jet. This is superimposed by a short term variability especially during early time (Delta t < 8 days). The cause of variability is not well understood, though it has occurred simultaneously with similar amplitude in all the filters. We derive the early and late time flux decay constants using jet model. The late time flux decay is the steepest amongst the GRB OTs observed so far with alpha ~ 3. Steepening in the flux decay seems to have started simultaneously around Delta t ~ 7.6 day in all passbands. The value of spectral index in the optical-near IR region is ~ -1.0. Redshift determination with z=2.0335 indicates cosmological origin of the GRB having a luminosity distance of 16.6 Gpc. Thus it becomes the second farthest amongst the GRBs with known distances. An indirect estimate of the fluence > 20 keV indicates, if isotropic,> =10^53 ergs of release of energy. The enormous amount of released energy will be reduced, if the radiation is beamed which is the case for this event. Using a jet break time of 7.6 days, we infer a jet opening angle of ~ 0.15 radian. This means the energy released is reduced by a factor of ~ 90 relative to the isotropic value.Comment: LaTeX file, 11 pages including 4 figures, uses psfig.sty, Bull. Astron. Society of India(accepted, Sept, 2000 issue

Electronic states of PrCoO3_3: X-ray photoemission spectroscopy and LDA+U density of states studies

Electronic states of PrCoO$_3$ are studied using x-ray photoemission spectroscopy. Pr 3d$_{5/2}$ core level and valence band (VB) were recorded using Mg K$_\beta$ source. The core level spectrum shows that the 3d$_{5/2}$ level is split into two components of multiplicity 4 and 2, respectively due to coupling of the spin states of the hole in 3d$_{5/2}$ with Pr 4f holes spin state. The observed splitting is 4.5 eV. The VB spectrum is interpreted using density of states (DOS) calculations under LDA and LDA+U. It is noted that LDA is not sufficient to explain the observed VB spectrum. Inclusion of on-site Coulomb correlation for Co 3d electrons in LDA+U calculations gives DOS which is useful in qualitative explanation of the ground state. However, it is necessary to include interactions between Pr 4f electrons to get better agreement with experimental VB spectrum. It is seen that the VB consists of Pr 4f, Co 3d and O 2p states. Pr 4f, Co 3d and O 2p bands are highly mixed indicating strong hybridization of these three states. The band near the Fermi level has about equal contributions from Pr 4f and O 2p states with somewhat smaller contribution from Co 3d states. Thus in the Zaanen, Sawatzky, and Allen scheme PrCoO$_3$ can be considered as charge transfer insulator. The charge transfer energy $\Delta$ can be obtained using LDA DOS calculations and the Coulomb-exchange energy U' from LDA+U. The explicit values for PrCoO$_3$ are $\Delta$ = 3.9 eV and U' = 5.5 eV; the crystal field splitting and 3d bandwidth of Co ions are also found to be 2.8 and 1.8 eV, respectively.Comment: 12 pages, 7 figures; to appear J. Phys.: Condens. Matte

Removal of arsenic from drinking water by precipitation and adsorption or cementation: An environmental prospective

The removal of arsenic from process solutions and effluents has been practiced by the mineral process industries for many years. More recently, because of the recognition that arsenic at low concentrations in drinking water causes severe health effects, the technologies that have been used in the mineral industry are being applied to that situation. Removal of arsenic in process solutions can be accomplished for most present day product specifications but the stability of solid and liquid waste materials for long-term disposal or discharge may not meet the regulatory requirements of the future. In the case of drinking water treatment where the requirement is to reduce arsenic to a few parts per billion, the applicable technologies are limited. This paper mentions briefly the aqueous inorganic chemistry of arsenic and the most common methods that have been applied commercially in the mineral industry for arsenic removal, recovery, and disposal. Some techniques, which have been used only in the laboratory, or otherwise suggested as means of eliminating or recovering arsenic from solution, are also outlined. Low cost removal of arsenic from drinking water is likely to be confined to precipitation, adsorption or cementation, but the sludge&rsquo;s created present stability concerns. This paper reviews some of the work done in relation to the mineral industry where there is also application to drinking water. Disposal of stable residues is critical in both situations, and the testing methods for assessing stability need careful consideration

Assessment of monthly variation in heavy metal characteristics of Electroplating industrial untreated wastewater at selected sites of Chandigarh

With the contest of urbanization and industrial development, electroplating industries have grown rapidly. The different chemicals, metal salts and discharge of large volume of wastewater with inefficient treatment facilities had created the pollution load on water bodies.  The present study was carried out to investigate the assessment of the monthly variation of pH and heavy metals (Cr, Ni, Zn, Fe) of electroplating untreated industrial wastewater from the selected study sites viz. SS-1: Atul Industries, SS-2: Suresh Fasteners, SS-3: Bajrang Industrial Company, SS-4: Stylex Industries, SS-5: Karan Industries, SS-6: Avon Industries, SS-7: Geetika Enterprises, SS-8: Atop Fasteners, SS-9: Accufit Fasteners and SS-10: Ashoka Furniture Udyog at industrial area phase I and phase II of Chandigarh. The untreated electroplating wastewater samples were collected from ten study sites (SS-1 to SS-10) and were analyzed following the standard methods for the examination of water and wastewater. The results of the present study revealed that the maximum concentration of heavy metals such as Zn (122.20 mg/l)during the month of August 2019 at the SS-8, Ni (156.37 mg/l) during the month of August 2019 at the SS-4, Cr (467.01 mg/l) during the month of October 2019 at the SS-5 and Fe (13.22 mg/l)during the month of December 2019 at the SS-2. The load of metallic ions discharge from the electroplating industries before any treatment from the selected study sites (SS-1 to SS-10) was found in the following order as Cr&gt;Ni&gt;Zn&gt;Fe. Thus the present study would provide baseline data for the development of treatment strategies for wastewater discharge from electroplating industries and also in minimizing the effects of heavy metal contamination of receiving water bodies