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Rekha, Kaliyaperumal,Sivasubramanian, Chandran,Chung, Ill-Min,Thiruvengadam, Muthu Hindawi Publishing Corporation 2014 BioMed research international Vol.2014 No.-
<P>Infectious bursal disease virus (IBDV) causes a highly contagious disease in young chicks and leads to significant economic losses in the poultry industry. To determine a suitable cell line for IBDV infection, replication, and growth kinetics of the virus, DF-1 cells and chicken embryo fibroblasts (CEF) were used. The population doubling per day (Pd/D) was found to be higher in DF-1 as compared to CEF cells. A suitable time of infection (TOI) was established for increased production of virus and greater infectivity titers. The DF-1 and CEF cells were found to be susceptible to infection by producing marked cytopathic effects (CPEs), and the growth curves of IBDV in DF-1 and CEF cells were evaluated by infectivity assay using tissue culture infectious dose (TCID<SUB>50</SUB>). The cytopathic effects of the virus in DF-1 and CEF cells were found to be similar, but higher viral titers were detected in the DF-1 cells as compared to CEF. Thus the DF-1 cell line had a higher growth potential and infectivity, which will be of advantage in vaccine production.</P>
Rekha Panda,Om Shankar Dinkar,Archana Kumari,Rajesh Gupta,Manis Kumar Jha,Devendra Deo Pathak 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-
Present research reports a novel and feasible process to recover Ag and generate concentrate of preciousmetals (Au, Pd and Pt) from waste ICs present in PCBs of computers. Initially, depopulated ICs werepulverized and beneficiated to obtain metallic concentrate, which contained (per ton) 7 Kg Ag, 5 Kg Au,110 g Pd and 4 g Pt along with Cu, Pb, Fe and Ni. Leaching was carried out and found that at optimizedcondition i.e. 3 M HNO3, temperature 80 C, pulp density 50 g/L and mixing time 1 h, >90% of Ag, Cu, Pband Ni were leached leaving Au, Pt and Pd in the residue. From the leach liquor, Ag was precipitated using1 M KCl in 30 min and other metals were recovered by precipitation, solvent extraction and cementationmethods. All wastes (solid/ liquid) generated during process development could be treated usingstandard environmental procedure.
Synthesis of SrFe12O19 and Sr7Fe10O22 systems for visible light photocatalytic studies
Rekha Dom 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.4
Solid state synthesis of two Sr-Fe-O systems viz. Sr7Fe10O22 and SrFe12O19 was attempted and they were investigated for their photocatalytic properties. Although, both the systems exhibited good cystallinity and optical properties, only Sr7Fe10O22 was found to be active for the photocatalytic decomposition of iso-propanol under visible light. It also yielded a significant quantum yield (~1.7%) for photo-reduction of water under visible light irradiation, much better than titanium oxy-nitride samples. The inactiveness of SrFe12O19 was due to its unsuitable band energetics. The Sr7Fe10O22 acted more efficiently than TiO2-xNx due to its suitable band positions and high visible light photon absorptivity.
Design and Analysis of a Frequency Reconfigurable Penta-Band Antenna for WLAN and 5G Applications
Rekha Shanmugam 한국전자파학회JEES 2021 Journal of Electromagnetic Engineering and Science Vol.21 No.3
This paper presents a discussion on a low-profile, frequency-reconfigurable penta-band antenna. This antenna consists of two asymmetric L-shaped rectangular patches electrically connected by a single PIN diode. The proposed antenna operates at five frequency bands depending upon the switching states of the PIN diode. It operates at 2.4 ㎓ (WLAN) and 5.3 ㎓ (5G) during forward bias of the diode, 3.3 ㎓ (5G) and 5.9 ㎓ (WLAN) during reverse bias of the diode and 4 ㎓ during zero bias condition providing a wide bandwidth (3.6–4.8 ㎓) at this state. The antenna has voltage standing wave ratio (VSWR) ranges from 1 to 2, gain value ranges from 2.6 to 5.0 ㏈i, and a maximum radiation efficiency of 85%. This antenna can be integrated with modern devices such as smart phones, laptops, and other handheld devices due to its simplistic geometry. A prototype of the model is fabricated, and the results are validated.
Leaching of rare earth metals (REMs) from Korean monazite concentrate
Rekha Panda,Manis Kumar Jha,이진영,Archana Kumari,Jhumki Hait,Vinay Kumar,J. Rajesh Kumar 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Systematic scientific studies for dephosphorization and acid leaching of Korean monazite are reported here. 50% NaOH (w/v) solubilizes 99.99% phosphate, at 170 ℃, 100 g/L pulp density in 4 h. Kinetics of phosphate leaching fitted well with model ‘‘chemical reaction control,’’ i.e. 1 - (1 - X)1/2 = kct, Ea = 58.04 kJ/mol. Further, rare earth hydroxides (REHs) was leached using 6 N HCl at 90 ℃, 60 g/L pulp density for 2 h to recover ~95% REMs. Leach liquor generated can be further processed using solvent extraction/ion exchange techniques. From the pure solutions, metal/salts could be obtained using evaporation, precipitation, etc.