Browsing by Author "Fanindra Pati Pandey"

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Dielectric and electro-optical properties of zinc ferrite nanoparticles dispersed nematic liquid crystal 4’-Heptyl-4-biphenylcarbonnitrile
(Taylor and Francis Ltd., 2020) Fanindra Pati Pandey; Ayushi Rastogi; Rajiv Manohar; Ravindra Dhar; Shri Singh
In this work, comprehensive results on dielectric and electro-optical properties of pristine and zinc ferrite (ZnFe2O4) nanoparticles (NPs) dispersed in host nematic 4ʹ-Heptyl-4-biphenylcarbonnitrile (7CB) systems are reported. The dielectric and EO properties of pristine and NPs dispersed (concentrations 0.05, 0.1, 0.15, 0.2, 0.3 and 0.5 wt%) into the host nematic system have been studied. We have seen uniform NPs dispersion into nematic 7CB up to 0.15 wt% concentration of NPs by the POM. The NPs aggregation starts at 0.2 wt% dispersion. It is shown that the dielectric and electro-optical properties are strongly influenced by the concentration of NPs in host nematic and applied electric field. The dielectric anisotropy is maximum for the NPs dispersed system of 0.15 wt% concentration. The Birefringence, parallel and perpendicular components of permittivity and conductivity are found to be dependent on temperature and concentration of NPs into host matrix. In pure nematic material, small memory is seen but in NPs dispersed systems noticeable memory is found. In particular, pronounced memory is found for the dispersed system of 0.3 wt% concentration of NPs. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.
Effect of carbonaceous oil palm leaf quantum dot dispersion in nematic liquid crystal on zeta potential, optical texture and dielectric properties
(Springer Medizin, 2021) Ayushi Rastogi; Fanindra Pati Pandey; Avanish Singh Parmar; Shri Singh; Gurumurthy Hegde; Rajiv Manohar
In the present work, the dispersion of oil palm leaf based carbonaceous quantum dots (OPL QDs) in nematic liquid crystal (NLC) E 48 eutectic mixture has been reported. The dispersed systems with concentrations 0.1, 0.2, and 0.3 wt% are designated respectively, as MIX 1, MIX 2, and MIX 3. The objective of this study is to analyze the results on the zeta potential, optical texture, dielectric constant, dielectric loss, conductivity, dielectric strength, relaxation frequency, specific power loss and total power loss of pure and OPL QDs dispersed nematic E 48 system. Zeta potential measurement has been performed in the solution state to ensure dispersion stability. The optical textures and dielectric results are recorded after filling the respective samples in sample cells. The core findings in the present study show that the zeta potential varies from − 23.43 mV to + 28.07 mV that signifies the stability of OPL QDs suspension in LCs. Specific power loss (SPL) and total power loss (TPL) are found to be least for MIX 1 which shows that the problem of high power consumption in LCDs can be resolved by dispersing a small weight percent concentration of OPL QDs in LC medium (MIX 1). Improved molecular alignment in the dispersed system has been observed from the textural study which finds its application in good contrast display devices. The color change in the aligned textures with temperature has been attributed to the birefringence change. The porous nature of carbonaceous OPL QDs has its application in supercapacitors. The benchmark results of this study highlight the effect of temperature and frequency on dielectric parameters for both planar and homeotropic state of E 48 LCs. OPL QDs dispersed system display increased conductivity for MIX 3. The decrease in the activation energy for OPL QDs dispersed system in comparison to pure LC material E 48 is a consequential result of the potential barrier change. The increment in the dielectric strength and relaxation frequency of OPL QDs dispersed system is noticed in comparison to pure E 48. These outcomes open the door for the applicability of present LCs in the field of both display and non-display devices like sensors, supercapacitors, low power consumption displays, energy conversion, and electrical storage devices as well as advanced smart systems. Graphical abstract: [Figure not available: see fulltext.]. © 2021, Islamic Azad University.
Electro-optic switching and memory effect in suspension of ferroelectric liquid crystal and iron oxide nanoparticles
(Institute of Physics Publishing, 2019) Abhishek Kumar Misra; Pankaj Kumar Tripathi; Kamal Kumar Pandey; Fanindra Pati Pandey; Shri Singh; Abhilasha Singh
In this work, impact of dispersion of iron oxide nanoparticles (Fe2O3 NPs) into ferroelectric liquid crystal (FLC) SCE-13 mixture on the electro-optical and dielectric properties has been studied. It has been found that the dispersion of Fe2O3 NPs in host FLC matrix exhibits pronounced influence on response time, spontaneous polarization, rotational viscosity and voltage required for switching the FLC molecules. Also dispersed system shows memory effect as confirmed by the optical texture and dielectric permittivity studies. Effort has been made to explain the experimental results as for as possible. © 2019 IOP Publishing Ltd.
Enhancing physical characteristics of thermotropic nematic liquid crystals by dispersing in various nanoparticles and their potential applications
(Institute for Ionics, 2023) Ayushi Rastogi; Archana Mishra; Fanindra Pati Pandey; Rajiv Manohar; Avanish Singh Parmar
Herein, we have summarized the doping of thermotropic nematic liquid crystals (LCs) with different nanoparticles (NPs) and its consequences on dielectric, optical, and electro-optical properties. The challenging task is to improve the physical properties of nematic LCs for its applications in nanotechnology, which include sophisticated and highly advanced modern displays, tunable lenses, sensors, etc. The negative effects that affect the overall performance of LCs devices are image sticking problem, image flickering, and slow response time which is mainly affected by ions and alignments. The trapping of charged ionic impurities and suppression of screening effect through NPs in LC medium produces strong electric field and van der Waal forces linked with the LC molecules and the alignment layers. The electric field controls the orientation of LC molecules and thus transforms its physical behavior. In this article, we have summarized and discussed the physical properties of thermotropic nematic LCs with the dispersion of NPs. These thermotropic LCs require improvement in their properties for the better functioning of LC products. A decade of enthusiastic research has designed the lane to the suspension of NPs in LC matrix for resolving the issues on nanotechnology. NPs (guest) that are embedded in LCs (hosts) influence its material parameters. The present article focuses on the review of published articles which report various types of NPs (metal oxide NPs, carbon-based NPs, semiconducting NPs, ferroelectric (FE) such as BaTiO3, magnetic NPs, and metallic NPs) as dopants and its sound realization on the physical properties of thermotropic nematic LCs. The topological defects and the effect of dispersion of colloidal particles in nematic LCs have been discussed. The decrease in the anchoring energy with decreasing radius of particles has been revealed. This review considers the significant role of NP self-assembly in LC medium which depends on its shape, size, and surface chemistry that affect the orientation order of LC molecules. From the application point of view, this review provides the literature support where the mixing of LCs and NPs solves the technological problems. The explanation on the improvement in the performance/material parameters is well supported by the experimental literature study reported in this review. © 2022, Qatar University and Springer Nature Switzerland AG.
Investigation of dielectric, optical and zeta potential properties of pure and zinc ferrite nanoparticles dispersed nematic liquid crystal PCH5
(Springer Science and Business Media Deutschland GmbH, 2022) Dhananjay Kumar Gaur; Fanindra Pati Pandey; Ayushi Rastogi; Avanish Singh Parmar; Rajiv Manohar; Shri Singh
The present work reports the results on dielectric and optical properties, and zeta potential of pure and zinc ferrite magnetic nanoparticles (ZnFe2O4 NPs) dispersed nematic liquid crystals (NLC) 4-(trans-4'-n-pentylcyclohexyl) benzonitrile (PCH5). The ZnFe2O4 NPs of three different concentration 0.25, 0.5 and 1.0 wt% have been dispersed in host nematic. The effect of ZnFe2O4 NP dispersion in NLC PCH5 on dielectric permittivity, dielectric anisotropy, ac conductivity, photoluminescence, Raman spectra and zeta potential has been studied. It has been observed that these properties are influenced by the concentrations of NPs in host nematic and applied electric field. Significant decrease in dielectric permittivity and dielectric anisotropy due to the presence of NPs in host nematic matrix has been observed. For the NP concentrations of 0.25 and 0.5 wt% in PCH5, photoluminescence intensity is increased, but it is decreased for the 1.0 wt% concentration of NPs in host nematic matrix. The numerical values of zeta potential are decreased with the concentrations of NPs. This result provides useful information on the stability and aggregation dynamics of the dispersed systems. In the profile of Raman spectra, variation in intensities is found for different orientations. An effort has been made to explain the observed results on the basis of interaction between NPs and nematic molecules. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
Label-Free Fluorometric Detection of Adulterant Malachite Green Using Carbon Dots Derived from the Medicinal Plant Source Ocimum tenuiflorum
(Wiley-Blackwell, 2019) Devyani Shukla; Fanindra Pati Pandey; Puja Kumari; Nilanjan Basu; Manish K. Tiwari; Jayeeta Lahiri; Ravindra N. Kharwar; Avanish S. Parmar
Food adulteration is an alarming concern in developing countries causing an increased rate of cancer incidents. This study aims to address this concern by detecting adulteration in green vegetables. A facile green one-step and cost-effective strategy to synthesize carbon quantum dots derived from a herbal source has been utilized to design a fluorescence-based sensor for detecting malachite green (MG), a toxic carcinogenic dye, commonly used as an adulterant to give a fresh green look to green vegetables. The leaf-extract of Ocimum tenuiflorum has been used to synthesize highly photostable carbon dots for detecting MG with a limit of detection (LOD) as low as 18 nM. Further, this principle has been utilized to design a prototype calorimetric sensor. The mechanism of the interaction between malachite green and carbon dots has been probed using DFT by employing the SMD solvation model. In addition, CQDs also possess strong antioxidant activity and minimal cytotoxicity enabling their utilization in many biological and sensing applications. This shows the versatility of these easily scalable carbon dots. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Optical properties and zeta potential of carbon quantum dots (CQDs) dispersed nematic liquid crystal 4′- heptyl-4-biphenylcarbonitrile (7CB)
(Elsevier B.V., 2020) Fanindra Pati Pandey; Ayushi Rastogi; Shri Singh
In this work, carbon quantum dots (CQDS) of three concentrations 0.1, 0.2 and 0.5 wt% have been dispersed in nematic liquid crystal 4′-Heptyl-4-biphenylcarbonitrile (7 CB). The results on the optical properties and zeta potential of pure and CQDs dispersed nematic 7CB have been reported. It has been observed that the dispersion of CQDs in host nematic matrix induces quenching of photoluminescence and reduces the Ultra-Violet-Visible (UV–Vis) absorbance of pure nematic at a lower wavelength. From the result of fluorescence decay profile, the fluorescence life time of pristine and dispersed nematic systems have been obtained. No remarkable changes in nematic lifetime in the presence of CQDs have been observed, which confirm that no energy is transferred from nematic to CQDs. Further, it has been found that due to dispersion of CQDs the numerical values of zeta potential are increased for the dispersed systems with 0.1 and 0.2 wt% concentrations of CQDs as compared to pure 7 CB. This result demonstrates that the study of zeta potential provides useful information on the stability and aggregation of the CQDs dispersed nematic systems. © 2020 Elsevier B.V.
Structural Modeling, Spectroscopic Signature and NBO Analysis of Octopamine and Its Radical
(John Wiley and Sons Inc, 2024) Nagendra Yadav; Tarun Yadav; Anil Kumar Vishwkarma; Subhendu Chakroborty; Pankaj Kumar Tripathi; Fanindra Pati Pandey; Amit Pathak; Mariyam Ansari
The present communication deals with theoretical vibrational spectroscopic signature (IR and Raman) of octopamine molecule and its radical. All theoretical calculations for octopamine and its radical are performed at DFT/B3LYP/6-31++G (d, p) level. Besides, the vibrational frequencies of these two structures has been compared. Most of the vibrational frequencies agree well with experimental ones. It has been documented how the geometrical characteristics and vibrational frequencies of octopamine are affected when hydrogen is removed from the oxygen atom's site. The HOMO-LUMO energy gap in the case of neutral form of octopamine is computed to be 5.42 eV while for deprotonated octopamine this gap has been increased by 0.78 eV. The NBO analysis is also performed to ensure stability of radical of octopamine. The magnitude of occupancy at bonding orbitals within the 0.997–0.885e, and 0.996–0.885e range in octopamine and octopamine, respectively, is calculated. © 2024 Wiley-VCH GmbH.
Time resolved fluorescence and Raman properties, and zeta potential of zinc ferrite nanoparticles dispersed nematic liquid crystal 4′-heptyl-4-biphenylcarbonitrile (7CB)
(Elsevier B.V., 2020) Fanindra Pati Pandey; Shri Singh
The present work reports the results on the time resolved fluorescence, Raman properties and Zeta potential of pristine and zinc ferrite nanoparticles (ZnFe2O4 NPs) dispersed nematic liquid crystal, 4′-heptyl-4-biphenylcarbonitrile (7CB). It has been observed that the dispersion of ZnFe2O4 NPs into nematic 7CB matrix induces quenching of photoluminescence, reduces the Ultra-Violet-Visible (UV‐–Vis) absorbance of pure nematic 7CB at lower wavelength, and increases the numerical value of zeta potential. The maxima in absorbance curve occur at the same wavelength but the absorbance is decreased. The emission peaks in pure nematic sample occur at 376 nm and 383 nm. Variations in the Raman intensity profile are observed for different orientations. This variation is more noticeable for the C[sbnd]C bond in aromatic ring and the C ≡ N group both located along the long axis of the nematic liquid crystal (NLCs) system. © 2020 Elsevier B.V.
Time-resolved fluorescence and UV absorbance study on Elaeis guineensis/oil palm leaf based carbon nanoparticles doped in nematic liquid crystals
(Elsevier B.V., 2020) Ayushi Rastogi; Fanindra Pati Pandey; Gurumurthy Hegde; Rajiv Manohar
Time resolved fluorescence measurement and UV absorbance study on oil palm leaf based nanoparticles (OPL) doped with nematic liquid crystal E 48 in 0.1, 0.2 and 0.3 wt/wt% concentration abbreviated as mixture 1 (MIX 1), mixture 2 (MIX 2) and mixture 3 (MIX 3) were conducted. OPL biomolecule loaded graphene oxide –nematic E 48 liquid crystal system has been fabricated for biosensor application. The interaction of OPL nanoparticles with E 48 nematic liquid crystal having different concentration of nanoparticles has been explored. Pure nematic E 48 and its doped system have been examined by time- resolved fluorescence spectroscopy (TRFS) technique. Variation in the nanoparticles concentration strappingly affects the fluorescence emissions. Lack of Förster resonance energy transfer (FRET) was found in all composites. This manuscript unveils the purpose of a range of factors, such as dipolar interface between donor and acceptor molecules, nanoparticles orientation and its proximity distance that may be accountable for the non-appearance of FRET. Nematic nanoparticles doped system forms an antique composition of luminescent material even though the fluorescence characteristics of host are customized in the existence of nanoparticles by the molecular alignment modification. Variation in lifetimes of nematic nanoparticles doped system has been observed. These results find its applicability in photonic displays, photovoltaic devices, biosensors etc. © 2020
Understanding the Interaction Mechanism between the Epinephrine Neurotransmitter and Small Gold Nanoclusters (Aun; n = 6, 8, and 10): A Computational Insight
(American Chemical Society, 2023) Nagendra Prasad Yadav; Tarun Yadav; Sangram Pattanaik; Ehsan Shakerzadeh; Subhendu Chakroborty; Cai Xiaofeng; Anil Kumar Vishwkarma; Amit Pathak; Jitendra Malviya; Fanindra Pati Pandey
In this study, the interaction between the neurotransmitter epinephrine and small gold nanoclusters (AunNCs) with n = 6, 8, and 10 is described by density functional theory calculations. The interaction of Au6, Au8, and Au10 nanoclusters with epinephrine is governed by Au-X (X = N and O) anchoring bonding and Au···H-X conventional hydrogen bonding. The interaction mechanism of epinephrine with gold nanoclusters is investigated in terms of electronic energy and geometrical properties. The adsorption energy values for the most favorable configurations of Au6NC@epinephrine, Au8NC@epinephrine, and Au10NC@epinephrine were calculated to be −17.45, −17.86, and −16.07 kcal/mol, respectively, in the gas phase. The results indicate a significant interaction of epinephrine with AunNCs and point to the application of the biomolecular complex AunNC@epinephrine in the fields of biosensing, drug delivery, bioimaging, and other applications. In addition, some important electronic properties, namely, the energy gap between HOMO and LUMO, the Fermi level, and the work function, were computed. The effect of aqueous media on adsorption energy and electronic parameters for the most favorable configurations was also studied to explore the influence of physical biological conditions. © 2024 The Authors. Published by American Chemical Society.