Browsing by Author "Pankaj Tripathi"

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People with HIV/AIDS: Stigma, Self-Esteem and Psychological Health
(Springer, 2024) Neena Kohli; Vipul Kumar; Shreshtha Yadav; Pankaj Tripathi
The major objectives of the present study were (a) to explore the perception of stigma associated with HIV/AIDS among people living with HIV/AIDS (PLWHAs); (b) to investigate the relationship between stigma, self-esteem and psychological health, and; (c) to examine the mediating role of self-esteem in the relationship between (a) felt stigma and psychological health, and; (b) enacted stigma and psychological health. The sample consisted of 200 HIV positive individuals (100 females and 100 males) from Prayagraj (North India). Data were collected using a set of questionnaires (self-report measure). It contained questions related to demographic information (age, gender, marital status, education and income), the experience of stigma, self-esteem and psychological health. Results revealed that perceived and enacted stigma were negatively correlated with self-esteem and psychological health. Enacted stigma emerged as a significant predictor (negative) of self-esteem and psychological health. Self-esteem also emerged as a significant predictor of psychological health. It also revealed that the relationship between enacted stigma and psychological health was significantly mediated by self-esteem. Based on the findings, it is suggested that PLWHAs should be treated with respect and dignity, and efforts should be made to align them with the mainstream. Further, they should be encouraged to think above stigma in order to have a better quality of life. © The Author(s) under exclusive licence to National Academy of Psychology (NAOP) India 2023.
Raman signature of the interaction between functionalized MWCNT and the liquid crystalline system (4DBA)
(American Institute of Physics, 2024) Ummer Bashir Khoja; Chandan Bhai Patel; Rajesh Srivastava; Vijay K. Mishra; Pankaj Tripathi; Amit Raj Singh; Ranjan K. Singh; K. Vikram
Liquid crystalline systems provide the best molecular matrix as a host for carbon nanotubes (CNTs) due to their fluidity character that controls the molecular ordering. The anisotropic shape of the CNTs makes them highly suitable nanoparticles that can be embedded in liquid crystalline systems to achieve uniform tunable dispersion. The uniform and stable dispersion of CNTs in the liquid crystalline host is challenging due to strong Vander Waal forces between CNTs. The functionalization of CNTs is one of the most popular techniques to achieve the dispersion system in an LC host due to the covalent bonding between CNT and LC systems. The COOH functionalized multi-wall carbon nanotubes (F-MWCNT) provide effective sites to interact with LC systems with the carboxylic group at the terminal. Raman spectroscopy is used as a probe to investigate the interaction between 4DBA and F-MWCNT through COOH - -COOH dimer formation. Comparative Raman analysis of 4DBA, 4DBA + bare MWCNT, and 4DBA + F-MWCNT spectra show bands associated with the COOH group giving strong evidence of interaction between 4DBA and F-MWCNT. Raman study reveals the mechanism of dimer formation between F-MWCNT and 4DBA. © 2024 Author(s).
Simulation study of dielectric resonator antenna with metamaterial for improvement of bandwidth and gain
(IEEE Computer Society, 2013) Bhagirath Sahu; Pankaj Tripathi; Rajesh Singh; S.P. Singh
The study of a compact aperture-coupled wideband dual segment rectangular dielectric resonator antenna (RDRA) with metamaterial for C-band applications are presented in this paper. The simulation study of the antenna is carried out using Ansoft's HFSS software. With the use of metamaterial superstrate, the bandwidth of the antenna is increased by 48 % through simulation. The broadside radiation pattern of the antenna is converted into directive radiation pattern with reduced beamwidth when metamaterial superstrate is used. The average gain of the antenna is also enhanced by 22 % through simulation with the use of metamaterial superstrate. © 2013 IEEE.
Synthesis and catalytic activity of Cu-Cr-O-TiO2 composites for the thermal decomposition of ammonium per-chlorate: enhanced decomposition rate of fuel for solid rocket motors
(Royal Society of Chemistry, 2017) Harish Kumar; Prahalad N. Tengli; Vijay Kumar Mishra; Pankaj Tripathi; Dan Bahadur Pal; Pradeep Kumar Mishra
This study presents the sol-gel synthesis of Cu-Cr-O·nTiO2 particles calcined at different temperatures and their catalytic effects on thermal decompostion of AP. The study focuses on the impact of crystallite size, shape and concentration of TiO2 in the catalyst composition on the thermal decomposition behaviour of ammonium per-chlorate (AP). During synthesis, the molar ratio of Cu/Cr was kept to 0.7 and TiO2 nanoparticles were added into Cu-Cr-O-citric acid solution at different molar ratios to form three different compositions of the catalyst Cu-Cr-O·nTiO2 (n = 0.5, 0.7 and 0.9 mol%). The effect of temperature on the thermal, structural and spectroscopic properties of the different Cu-Cr-O compositions was also studied by calcining them at two different temperatures, 300 and 1050 °C. Post synthesis characterizations of the prepared catalysts were carried out by using XRD, FT-IR, SEM, EDAX and TEM (with SAED pattern) techniques. The desired qualification of Cu-Cr-O-citric acid (the precursor of the catalyst) and the final compositions of the catalysts were carried out by using thermogravimetric and differential thermal analysis (TG-DTA) techniques. The efficiency of the synthesized catalysts was evaluated on thermal decomposition behaviour of AP using TG-DTA techniques. The Cu-Cr-O·nTiO2 composition with the molar ratio of n = 0.7 was found to be the most efficient catalyst for decomposition of AP; it was much better than other laboratory prepared samples (n = 0.5 and 0.9) as well as the industrial catalyst (i.e. activated copper chromite (ACR); Cu-Cr-O). Further experimental work showed that addition of 10 wt% Cu-Cr-O·0.7TiO2 into AP significantly lowered the AP decomposition temperature to 306 °C from 385 °C and was accompanied by a very sharp exothermic peak indicating a single stage decomposition. The excellent finding of the study was also verified by heat of reaction (i.e. calibrated delta H) values. This study finds potential application due to the remarkable enhancement in the thermal decomposition rate of the AP used as oxidizer in propellant of solid rocket motors (SRMs) and space vehicles (SVs) at lower decomposition temperature. The fast decomposition rate of oxidizer at lower decomposition temperature enhances the efficiency of fuel which ultimately will enhance the efficiency of SRMs and SVs. © The Royal Society of Chemistry.
The effect of reduced graphene oxide on the catalytic activity of Cu-Cr-O-TiO2 to enhance the thermal decomposition rate of ammonium perchlorate: An efficient fuel oxidizer for solid rocket motors and missiles
(Royal Society of Chemistry, 2017) Harish Kumar; Prahalad N. Tengli; Vijay Kumar Mishra; Pankaj Tripathi; Awani Bhushan; Pradeep Kumar Mishra
Reduced graphene oxide (rGO) modified transition metal oxide based composites were successfully synthesized via a sol-gel assisted Hummers' method. The present study includes the synthesis of CuCr2O4·0.7TiO2, the synthesis of rGO and the synthesis of rGO modified CuCr2O4·0.7TiO2. In order to synthesize the desired catalyst, rGO and Cu-Cr-O-0.7TiO2 were synthesized individually. The CuCr2O4·0.7TiO2 composite was synthesized via a sol-gel method. Reduced graphene oxide (rGO) used as a modifier in the catalyst, was also synthesized in the laboratory and was calcined at high temperature (1050 °C) to improve its activity. Finally, Cu-Cr-O-0.7TiO2 was modified with 10 wt% rGO. The post synthesis characterizations were performed using various instrumental techniques including X-ray diffraction (XRD) for phase analysis, Fourier transform infrared (FTIR) and Raman spectroscopy for molecular interactions, scanning electron microscopy (SEM) for surface morphology, energy dispersive X-ray analysis (EDX), elemental analysis and X-ray photoelectron spectroscopy (XPS) for binding energy. The catalytic efficiency of the synthesized composite catalyst samples based thermal decomposition of the host material (i.e. AP) was determined by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The rGO modification into the Cu-Cr-O-0.7TiO2 tri-metallic composition made it the most promising catalyst for the thermal decomposition of AP, due to the tremendously high electrical and thermal conductivity of rGO. Different amounts (2.5, 5.0, 7.5 and 10 wt%) of Cu-Cr-O-0.7TiO2-rGO were added to ammonium perchlorate (AP) to investigate its effect on the thermal decomposition of AP, which is a well known oxidizer used worldwide in the solid composite propellant (SCP) in modern rocketry. The 5 wt% of catalyst (Cu-Cr-O-0.7TiO2-rGO) addition into AP exhibited the remarkably enhanced thermal decomposition of AP. Finally, the burn rate of SCP was examined with 5 wt% catalyst modified AP. The 5 wt% of catalyst modified AP exhibited 175.31% higher burn rate of SCP, compared to the burn rate of pure AP added SCP. Furthermore, when it was compared with an industrial catalyst, i.e. activated copper chromite (ACR), it showed 133.61% higher burn rate of SCP. The SCP exhibited excellent ballistic performance with 0.6% of catalyst in AP, which enhanced the burn rate from 4.866 mm s-1 (for SCP having pure AP) to 8.531 mm s-1 (for SCP having catalyst added AP) and 6.385 mm s-1 (for SCP having industrial catalyst added AP) at 33 bar. © 2017 The Royal Society of Chemistry.