8 MeV electron irradiation studies on electrical characteristics of Cu(In,Ga)Se2 solar cells

Cu(In,Ga)Se₂ (CIGS) solar cells are gaining considerable interest due to their high optical absorption coefficient and adjustable band gap, which enables them to achieve high conversion efficiency and also present many promising applications in space power systems. In this paper we report the results of the effect of temperature and 8 MeV electron irradiation on the electrical characteristics of ZnO/CdS/Cu(In,Ga)Se₂/Mo polycrystalline thin-film solar cells under forward and reverse bias studied in the temperature range 270-315 K. The solar cells were subjected to 8 MeV electron irradiation from the Microtron accelerator and were exposed to graded doses of electrons up to 75 kGy. I-V characteristics of the cells under dark and AM 1.5 illumination condition were studied before and after the irradiation. Capacitance measurements were also carried out at various frequencies before and after irradiation. In the measured temperature range, the dark current contribution is due to the generation-recombination of the minority carriers in the depletion region. The ideality factor is found to decrease with increase in temperature. It seems that electron irradiation has not altered the dark current conduction mechanism significantly. The effect of electron irradiation on the solar cell parameters such as fill factor (FF), conversion efficiency (η), saturation current (I_o), short circuit current (I_sc), open circuit voltage (V_oc), and ideality factor (n) was studied. They were found to be stable up to 75 kGy of electron dose as only small changes were observed in the solar cell parameters.     

Experimental determination of photofission cross-sections of Th using electron accelerator

Photofission cross-section of ²³²Th was measured using Bremsstrahlung radiation energy 7.4–9.2 MeV with energy step of 0.3 MeV by employing Lexan polycarbonate film as Solid State Nuclear Track Detectors (SSNTD). The photon intensity from the Microtron accelerator facility was estimated to be 10¹⁰ photons/s at a distance of 15 cm from the Bremsstrahlung converter using EGS-4 code (Nelson et al., 1985). Photofission cross-sections were evaluated using fission fragment angular distribution measurements. The present experimental results were compared with EMPIRE-2.19 (Herman et al., 2005) code prediction of RIPL-1 and RIPL-2 ( and ) and a new analytical formula (Gupta and Saxena, 2005) for fission barrier.     

Comprehensive Understanding of Urban Water Supply Management: Towards Sustainable Water-socio-economic-health-environment Nexus

Water Resources Management - The majority of the cities across the developing countries have saddled water supply and quality management issues. Unfortunately, even cities with adequate water...     

Pd/Fe3O4 supported on bio-waste derived cellulosic-carbon as a nanocatalyst for C–C coupling and electrocatalytic application

The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supported-palladium nanoparticles enriched magnetic nanocatalyst (Pd/Fe₃O₄@C) using a simple multi-step process under aerobic conditions. Under mild reaction conditions, the Pd/Fe₃O₄@C magnetic nanocatalyst demonstrated excellent catalytic activity in the Hiyama cross-coupling reaction for a variety of substrates. Also, the Pd/Fe₃O₄@C magnetic nanocatalyst exhibited excellent catalytic activity up to five recycles without significant catalytic activity loss in the Hiyama cross-coupling reaction. Also, we explored the use of Pd/Fe₃O₄@C magnetic nanocatalyst as an electrocatalyst for hydrogen evolution reaction. Interestingly, the Pd/Fe₃O₄@C magnetic nanocatalyst exhibited better electrochemical activity compared to bare carbon and magnetite (Fe₃O₄ nanoparticles) with an overpotential of 293 mV at a current density of 10 mA·cm^–2.     

Complex Mutation Pattern of Omicron BA.2: Evading Antibodies without Losing Receptor Interactions

BA.2, a sublineage of Omicron BA.1, is now prominent in many parts of the world. Early reports have indicated that BA.2 is more infectious than BA.1. To gain insight into BA.2 mutation profile and the resulting impact of mutations on interactions with receptor and/or monoclonal antibodies, we analyzed available sequences, structures of Spike/receptor and Spike/antibody complexes, and conducted molecular dynamics simulations. The results showed that BA.2 had 50 high-prevalent mutations, compared to 48 in BA.1. Additionally, 17 BA.1 mutations were not present in BA.2. Instead, BA.2 had 19 unique mutations and a signature Delta variant mutation (G142D). The BA.2 had 28 signature mutations in Spike, compared to 30 in BA.1. This was due to two revertant mutations, S446G and S496G, in the receptor-binding domain (RBD), making BA.2 somewhat similar to Wuhan-Hu-1 (WT), which had G446 and G496. The molecular dynamics simulations showed that the RBD consisting of G446/G496 was more stable than S446/S496 containing RBD. Thus, our analyses suggested that BA.2 evolved with novel mutations (i) to maintain receptor binding similar to WT, (ii) evade the antibody binding greater than BA.1, and (iii) acquire mutation of the Delta variant that may be associated with the high infectivity.     

Estimation of photoneutron yield from beryllium target irradiated by variable energy microtron-based bremsstrahlung radiation

The possibility of setting up microtron-based photoneutron source by utilizing bremsstrahlung radiation interaction with beryllium targets is critically examined. The bremsstrahlung yield for tantalum (Ta) target is obtained by EGS4 simulation. The neutron yield is estimated theoretically by MCNP simulation. The yield was measured experimentally by neutron irradiation of calibrated SSNTD CR-39 films. The total neutron yield is found to be of the order 10¹⁰ n/s for 250 Hz PRR and 10⁹ n/s for 50 Hz PRR. A detailed comparison shows good agreement between theoretical and experimentally measured yields.     

Comparison of photoneutron yield from beryllium irradiated with bremsstrahlung radiation of different peak energy

In an effort to set up microtron based photoneutron source and in order to optimize the neutron yield, photoneutron production from beryllium has been studied for different volumes of beryllium irradiated by different peak energy bremsstrahlung radiation. The theoretical estimation of neutron yield has been carried out using the MCNP simulation for 8.75, 8.15 and 7.58 MeV peak energy of bremsstrahlung radiation. The experimental measurements were carried out using two types of detectors: SSNTD CR-39 and custom designed Silver wrapped GM detector. The neutron yield corresponding to beryllium of volume 381.70 cm³ are found to be 2.13E+09, 2.00E+09 and 1.74E09 n/s (MCNP calculation values) for electrons of energy 8.75, 8.17 and 7.48 MeV, respectively. The experimental results are compared with the MCNP simulated results and are good agreement.