51. Tuning the thermal diffusivity of the seed matter for enhanced biosynthesis: A thermal lens studyMohanachandran Nair Sindhu Swapna, Sankararaman S, 2020, original scientific article Abstract: The thermodynamics of the seed matter after imbibition is highly significant as the growth and germination involve complex biochemical exergonic process. The germination of seed and compositional variation of the seed matter has always been a fascinating field of research. The present work unveils the thermodynamics associated with the changing thermal diffusivity of the seed matter through the green technology-based single-beam thermal lens technique. Investigations are carried out in Vigna radiata seeds, germinating in media with and without carbon allotropes, through various spectroscopic techniques. The morphology of the soot and carbon allotropes is understood from the field emission scanning electron microscope images. The thermal lens study throws light into the energy trapping nature of the seed matter of the seed growing in carbon allotropic media which facilitates biosynthesis. The observed increased rate of growth of the seed is substantiated through
the ultraviolet–visible–near-infrared (NIR), Fourier transform infrared, and photoluminescence (PL) spectroscopic analyses. The NIR and PL studies also reveal the formation of chlorophyll molecule during germination. Thus, the study suggests a mechanism for tuning the thermal diffusivity of the seed matter as to trap the biochemical energy to facilitate the further biosynthesis and thereby to enhance the growth rate.
Keywords: seed matter, thermal diffusivity, thermal lens, carbon nanoparticle, soot
Published in RUNG: 04.07.2022; Views: 1178; Downloads: 0
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52. Absolute Porosity Analysis in Carbon Allotropic Nanofluids: A Sankar–Swapna Model ApproachMohanachandran Nair Sindhu Swapna, SREEJYOTHI S, Sankararaman S, 2020, original scientific article Abstract: Porous materials have gained significant attention in recent years as a class of material exhibiting
interesting chemical and physical properties. The existing methods of porosity analysis have limitations that
prevent absolute porosity measurement. Hence, a technique independent of surface physical properties alone
can give the absolute porosity of the material. The porosity greatly influences the thermal diffusivity of a
material. The manuscript is the first report of employing the Sankar–Swapna model for analyzing the porosity variations in carbon allotropic nanofluids. The model helps not only in getting information about the absolute porosity variations among samples, but also suggests morphological modifications through the thermal diffusivity study using the sensitive single-beam thermal lens technique. The variations in thermal diffusivity and absolute porosity values are also correlated to morphological modifications based on the theoretical model and thereby proposing this as a surrogate method for absolute porosity analysis.
Keywords: absolute porosity, Sankar–Swapna model, thermal diffusivity, thermal lens, thermal conductivity
Published in RUNG: 04.07.2022; Views: 1181; Downloads: 0
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53. Organometallic sodium carbide for heat transfer applications: A thermal lens studyMohanachandran Nair Sindhu Swapna, Sankararaman S, 2020, original scientific article Abstract: The search for excellent heat transfer fuids necessitates the development of novel nanofuids. The paper is the frst report revealing the potential of sodium carbide (Na2C2) nanoparticle for heat transfer and thermal shielding applications. For this,
Na2C2 is prepared from the porous carbon matrix of Aloe vera leaves by hydrothermal method. The morphological changes on hydrothermal treatment and the thermal stability are analyzed by Field Emission Scanning Electron Microscopy and Thermogravimetry. The X-ray difraction analysis reveals the formation of sodium
carbide, which is confrmed by Fourier transform infrared, Ultraviolet–Visible–Near Infrared, and Raman spectroscopic analyses. The spectroscopic study of the sample synthesized shows indirect bandgap energy of 1.58 eV. The thermal difusivity
of Na2C2 nanofuid, determined by the single-beam thermal lens technique, exhibited 87 % enhancement for the base fuid, suggesting its potential in heat transfer applications.
Keywords: Aloe vera, Heat transfer, Organometallic, Sodium carbide, Thermal
lens
Published in RUNG: 04.07.2022; Views: 1058; Downloads: 0
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54. The efflorescent carbon allotropes: Fractality preserved blooming through alkali treatment and exfoliationMohanachandran Nair Sindhu Swapna, Sankararaman S, 2020, original scientific article Abstract: The work reported in the paper elucidates morphological modification induced nanoart and surface area enhancement of graphite, graphene, and soot containing carbon allotropes through ultrasonication and alkali-treatment. The field emission scanning electron microscopic (FESEM) analysis of the
samples before and after exfoliation reveals the formation of brilliant flower-like structures from spindle-like basic units due to Ostwald ripening. The x-ray diffraction analysis of the samples gives information about structural composition. The fractal analysis of the FESEM images indicates a
multifractal structure with the dimensions—box-counting dimension D0 (1.72), information dimension D1 (1.66), and correlation dimension D2 (1.63)—preserved upon exfoliation. The process of ultra-sonication assisted liquid phase exfoliation resembles blooming as if the carbon allotropes are efflorescent.
Keywords: carbon allotropes, fractal dimension, soot, fractality, alkali treatment, exfoliation
Published in RUNG: 04.07.2022; Views: 1191; Downloads: 0
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55. Fractal Applications in Bio-NanosystemsMohanachandran Nair Sindhu Swapna, Sankararaman S, 2019, review article Abstract: We live in a world of high complexity in all means. The present article is an attempt to elucidate the potential of fractal analysis in understanding and quantifying the complexity. Of several methods of fractal analysis, we have used only the box counting and power spectral methods for explaining the potential of the technique. The application of fractal analysis in bio-nanosystems, thin films, are forensic science are
exemplified though our own work.
Keywords: fractal application, bionanosystem
Published in RUNG: 04.07.2022; Views: 938; Downloads: 0
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56. Fractal and spectroscopic analysis of soot from internal combustion enginesMohanachandran Nair Sindhu Swapna, SARITHA DEVI H V, RAJ VIMAL, Sankararaman S, 2018, original scientific article Abstract: Today diesel engines are used worldwide for various applications and very importantly in transportation. Hydrocarbons are the most widespread precursors among carbon sources employed in the production of carbon nanotubes (CNTs). The aging of internal combustion engine is an important parameter in deciding the carbon emission and particulate matter due to incomplete combustion of fuel. In the present work, an attempt has been made for the effective utilization of the aged engines for potential applicationapplications in fuel cells and nanoelectronics. To analyze the impact of aging, the particulate matter rich in carbon content areis collected from diesel engines of different ages. The soot with CNTs is purified by the liquid phase oxidation method and analyzed by Field Emission Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, Energy Dispersive Spectroscopy, UV-Visible spectroscopy, Raman spectroscopy and Thermogravimetric analysis. The SEM image contains self-similar patterns probing fractal analysis. The fractal dimensions of the samples are determined by the box counting method. We could find a greater amount of single-walled carbon nanotubes (SWCNTs) in the particulate matter emitted by aged diesel engines and thereby giving information about the combustion efficiency of the engine. The SWCNT rich sample finds a wide range of applications in nanoelectronics and thereby pointing a potential use of these aged engines.
Keywords: Fractals, internal combustion engine, efficiency, soot, carbon nanoparticle
Published in RUNG: 30.06.2022; Views: 1200; Downloads: 0
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57. From futile to fruitful: Diesel soot as white light emitterMohanachandran Nair Sindhu Swapna, Sankararaman S, 2018, original scientific article Abstract: The present work describes a solution for the effective use of the hazardous particulate matter (diesel soot) from the internal combustion engines (ICEs) as a potential material emitting white light for white light emitting diodes (WLEDs). The washed soot samples are subjected to Field Emission Scanning Electron Microscopy (FESEM), High- Resolution Transmission Electron Microscopy (HR-TEM), Energy Dispersive Spectroscopy (EDS), UV-Visible, Photoluminescent (PL) Spectroscopy and quantum yield measurements. The CIE plot and Correlated Color Temperature (CCT) reveals the white fluorescence on photoexcitation. The sample on ultraviolet (UV) laser excitation, provides a visual confirmation of white light emission from the sample. The diesel soot collected from public transport buses of different years of manufacture invariably exhibit white fluorescence at an excitation of 350 nm. The sample show a quantum yield of 47.09%. The study is significant in the context of pollution and search for low-cost, rare-earth phosphor free material for white light emission and thereby turning the hazardous, futile material into a fruitful material that can be used for potential applications in photonics and electronics.
Keywords: White light emitter, Diesel soot, CIE plot, Quantum yield, Fluorescence
Published in RUNG: 30.06.2022; Views: 1081; Downloads: 0
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58. Blue light emitting diesel soot for photonic applicationsMohanachandran Nair Sindhu Swapna, Sankararaman S, 2018, original scientific article Abstract: The present work is the first report of producing blue light emission from phosphor free and low-cost material—the diesel soot from the internal combustion engines (ICEs). The structural morphology is analyzed by field emission scanning electron microscopy and high-resolution transmission electron microscopy. The optical characterization is done by recording UV–visible spectrum and photoluminescent Spectrum. The CIE plot and the power spectrum for the sample show blue emission. This is further verified by collecting diesel soot from the ICE of different year of make. A visual confirmation of blue emission is obtained by exciting the sample with UV laser. The presence of various allotropic forms of carbon in the sample is identified by x-ray diffraction, Fourier transform infrared and Raman spectroscopic analysis.
Keywords: blue light emitter, diesel soot, photoluminescence, CIE plot
Published in RUNG: 30.06.2022; Views: 1093; Downloads: 0
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59. Fractal analysis - a surrogate technique for material characterizationMohanachandran Nair Sindhu Swapna, Sankararaman S, 2017, original scientific article Abstract: Fractal analysis has emerged as a potential analytical tool in almost all branches of science and technology. The paper is the first report of using fractal dimension as a surrogate technique for estimating particle size. A regression equation is set connecting the soot particle size and fractal dimension, after investigating the Field Emission Scanning Electron Microscopic (FESEM) images of carbonaceous soot from five different sources. Since the fractal dimension is an invariant property under the scale transformation, an ordinary photograph of the soot should
also yield the same fractal dimension. This enables one to determine the average size of the soot particles, using the regression equation, by calculating the fractal dimension from the photograph. Hence, instead of frequent measurement of average particle size from FESEM, this technique of estimating the particle size from the fractal dimension of the soot photograph, is found to be a potentially cost-effective and non-contact method.
Keywords: fractals, FESEM, carbon nanoparticles, particle size, box-counting
Published in RUNG: 30.06.2022; Views: 1165; Downloads: 0
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60. Camphor soot: A Tunable Light EmitterMohanachandran Nair Sindhu Swapna, SARITHA DEVI H V, Sankararaman S, 2018, original scientific article Abstract: The work in this paper is the first report on the green synthesis of the blue light emitter from waxy, flammable solid collected
from Cinnamomum camphora by controlled combustion for photonic applications. Analysis with field emission scanning
electron microscope and high-resolution transmission electron microscope provides the morphology, whereas the thermo-gravimetric analysis gives the thermal stability of the soot. The optical and structural characterizations are done by recording
UV–Visible, Photoluminescent, and Raman Spectrum. The CIE plot and the power spectrum of the sample show a blue
emission at an excitation of 350 nm at room temperature with a quantum yield of 46.15%. The dependence of luminescent
behavior on temperature and excitation wavelength reveals that the material is a tunable blue emitter. This green synthesis of
the blue light emitter is highly significant, when the world is in search of a simple, phosphor-free, non-toxic, cost-effective
material with good quantum efficiency
Keywords: camphor, soot, blue light emitter
Published in RUNG: 30.06.2022; Views: 996; Downloads: 0
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