Srashti Gupta

Enhancement of thermoelectric power of PbTe:Ag nanocomposite thin films

The present study focuses on the enhancement of thermoelectric power of PbTe:Ag nanocomposite thin films, synthesized by the thermal evaporation technique. Thermoelectric measurements were carried out from room temperature to 400 K. It is observed that Ag addition improves the thermoelectric power and crystalline nature of the PbTe thin films. Synchrotron based X-ray diffraction was performed to confirm the phases of the Pb–Ag–Te alloy. This was further reconfirmed by X-ray photoelectron spectroscopy (XPS) and showed the precipitation of Pb on the surface of the PbTe:Ag films. The enhancement of thermoelectric power is thus attributed to the formation of Ag2−xTe alloy and the precipitation of Pb nanostructures on the surface. The origin of such enhancement is understood based on the phenomenon of energy dependent filtering of charge carriers.

Comparative cardioprotective effects and mechanisms of vitamin E and lisinopril against ischemic reperfusion induced cardiac toxicity

The present study was undertaken to scientifically evaluate, validate and compare the cardioprotective effects of lisinopril (Lsp), an angiotensin converting enzyme (ACE) inhibitor and vitamin E (Vit E), an antioxidant in the setting of ischemia and reperfusion (I-R) injury. An open chest left anterior descending coronary artery occlusion and reperfusion induced myocardial injury cardiotoxicity model was used in the present study. Hemodynamic, biochemical and histopathological assessment of myocardial injury was undertaken. Pre-treatment (1 month) with Lsp (50 mg/kg) and Vit E (100 mg/kg) to healthy experimental controls did not adversely affect the histopathological architecture of the myocardium as well as the baseline antioxidant parameters. Subsequent to I-R injury, Lsp demonstrated modest antioxidant effects, superior recovery in left ventricular function as compared to the control IR group. Histopathological and biochemical assessment of injury confirmed the myocardial salvaging effect of this intervention. The cardioprotection afforded by Lsp was found to be superior as compared to Vit E treatment.

Phase evolution and electrical properties of Co–Sb alloys fabricated from Co/Sb bilayers by thermal annealing and ion beam mixing

An investigation was carried out to understand the phase evolution and study the structural, morphological, optical and electrical properties of Co-Sb alloys fabricated by two different approaches: (a) thermal annealing and (b) ion-beam mixing followed by post annealing. The as-deposited and 100 MeV Ag ion beam irradiated Co/Sb bilayer thin films were subjected to thermal annealing from 200 to 400 °C for 1 hour. The Rutherford backscattering spectrometry (RBS) results showed partial mixing for the thermally annealed films and complete mixing for the irradiated and post annealed films at 400 °C. The XRD and RAMAN measurements indicated the formation of Co-Sb alloy, with ∼70% concentration of CoSb3 phase in the irradiated post annealed sample at 400 °C. The band gaps of the annealed and post irradiated annealed Co-Sb alloys were determined using UV-visible spectroscopy. Electrical and thermoelectric power measurements were performed in the temperature range of 300-420 K. It was observed that the alloys formed by ion-beam induced mixing exhibited higher electrical conductivity and thermoelectric power than the as-deposited and thermally annealed Co/Sb bilayer thin films.

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Pharmacovigilance in India: Present Scenario and Future Challenges

Pharmacovigilance in India was initiated way back in 1986 with a formal adverse drug reaction (ADR) monitoring system, under supervision of the drug controller of India. India joined the World Health Organization (WHO) Programme for International Drug Monitoring in 1998, but was not successful. Later, the National Programme of Pharmacovigilance was launched in 2005, and was renamed as the Pharmacovigilance Programme of India (PvPI) in 2010. In consideration of having a robust pharmacovigilance system in India, steps were taken. The National Coordination Centre was shifted from New Delhi to the Indian Pharmacopoeia Commission (IPC) in Ghaziabad. The PvPI works to safeguard the health of the Indian population by ensuring that the benefit of medicines outweighs the risks associated with their use. The culture of reporting of ADRs has achieved remarkable success, with 250 PvPI-established adverse drug monitoring centres all over India and provision of training to healthcare professionals. The programme is striving hard to build trust between the physician and the patient, thereby increasing patient safety and the confidence of people in the country’s health system, in addition to the detection of substandard medicines and prescribing, dispensing and administration errors. The IPC-PvPI has now become a WHO Collaborating Centre for Pharmacovigilance in Public Health Programmes and Regulatory Services. In spite of these achievements, several challenges are faced by the PvPI, like the monitoring of generic drugs, biosimilars, and disease-specific ADRs of antidiabetic, cardiovascular and antipsychotic drugs and, above all, creating awareness, which is a continual process. At the same time, the PvPI is trying to address other challenges like counterfeit drugs, antimicrobial resistance, and surveillance during mass vaccinations and other national programmes.

Effect of Ag doping and annealing on thermoelectric properties of PbTe

The present study reveals that annealing Ag doped PbTe thin films enhance thermoelectric properties. Phase formation was identified by using X-ray diffraction measurement. Annealing increases the crystallinity of both undoped and Ag doped PbTe. Electrical resistivity and thermoelectric power measurements are done using four probe and bridge method respectively. The increase in thermoelectric power of Ag doped PbTe is 29 % in comparison to undoped PbTe and it further increases to 34 % after annealing at 250o C for 1 hour whereas thermoelectric power increases by 14 % on annealing undoped PbTe thin films at same temperature.

Synthesis of PbTe thermoelectric film by high energy heavy ion beam mixing

The Te/Pb bilayer samples were prepared by sequential thermal evaporation of Pb and Te on glass substrate. These bilayer samples were irradiated by 100 MeV Ag9+ at different fluences (3×1012, 1×1013, and 3×1013 ions/cm2) to synthesis PbTe by ion beam mixing. The samples were characterized by RBS to study composition and X‐ray diffraction (XRD) for phase identification before and after irradiation. Thickness of Pb and Te were 75 nm and 105 nm respectively in pristine film as deduced from RBS analysis. The RBS of irradiated sample indicates the mixing between Pb and Te layers. XRD revealed phases of PbTe in sample irradiated at 3×1013 ions/cm2. This phase formation may be due to inter diffusion across the interface induced by swift heavy ion irradiation.