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35. Carbon nanoparticles assisted energy transport mechanism in leaves: A thermal lens studyMohanachandran Nair Sindhu Swapna, 2019, izvirni znanstveni članek Opis: In the world of increasing population and pollution due to carbon emissions, the research for effective utilization of futile diesel soot for fruitful applications has become a necessity for a sustainable development. The contribution to pollution from vehicles and industries due to the aging of engines has caused a crisis. Carbon nanoparticles (CNPs) have been the subject of interest because of their good physical, chemical, and biological properties. The present work investigates the role of CNPs produced by internal combustion engines on the energy transport mechanism among leaf pigments using the sensitive and nondestructive single beam thermal lens technique. The studies reveal the absorption changes by various chlorophyll pigments with the concentration of CNPs sprayed on the leaves. Though for low concentrations CNPs lower the photon absorbance by chlorophyll pigments, the effect gets reversed at higher concentrations. The variation of thermal diffusivity with CNP concentration and its role in the energy transport mechanism among chlorophyll pigments are also studied. It is found that CNP concentrations of 625-2500mg/l are good for better intra-pigment energy transport leading to increased rate of photosynthesis and plant yield and thereby helping in attaining food security. The variation of CNP assisted energy transport among leaf pigments on the production of nicotinamide adenine dinucleotide phosphate (NADPH) and carbohydrates is also studied with ultraviolet (UV) and near-infrared (NIR) spectroscopy.
Ključne besede: carbon nanoparticle, soot, energy transport, thermal lens, photosynthesis
Objavljeno v RUNG: 05.07.2022; Ogledov: 1177; Prenosov: 0
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36. Thermal induced order fluctuations in carbon nanosystem with carbon nanotubesMohanachandran Nair Sindhu Swapna, Sankararaman S, 2019, izvirni znanstveni članek Opis: The allotropes of carbon nanomaterials such as carbon nanotubes (CNTs) and nanoparticles (CNPs) have emerged as a thrust area of research during the last decade because of their unique properties.CNTs are widely used in microelectronic, sensor, bio-imaging, supercapacitors, fuel cell, and etc.
applications. In the present work, we report the thermal induced order fluctuations in the CNPs with CNTs synthesized from camphor. The samples annealed to different temperatures are characterized by various spectroscopic techniques such as UV–Visible, Raman, Fourier Transform Infrared, and X-ray Photoelectron Spectroscopy. Samples’ structure and morphology are analyzed by scanning and transmission electron microscopes, and X-ray diffraction. The thermogravimetric analysis indicates
not only the mass variation upon annealing but the thermal stability also. The spectroscopic and thermal analyses reveal the thermal induced oscillations in the carbon system which can be assigned to the dynamics in CNTs through desorption of hydrogen/ thinning or shortening of multi-walled CNTs/sp2 - sp3 conversions and the removal of amorphous carbon (AC). Since the amount of CNTs in the sample decides the electrical behavior, the sample can be tuned to a desired electrical conductivity
by annealing and thus making it a tunable material for electronic applications.
Ključne besede: Carbon nanotubes, Camphor, Thermal induced oscillations
Objavljeno v RUNG: 05.07.2022; Ogledov: 1015; Prenosov: 0
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37. Generalized Theory of Thermal Conductivity for Different Media: Solids to NanofluidsMohanachandran Nair Sindhu Swapna, Sankararaman S, 2019, izvirni znanstveni članek Opis: The advent of nanotechnology in the 21st
century opened a new branch of nanoscience known as
nanofluids, finding a wide range of industrial applications
especially in heat transfer. Though the theory of thermal
conductivity of solids is well established, there is no such
conclusive model to explain the thermal conductivity of
nanofluids. In the present work we propose a generalized
theory for thermal conductivity applicable to materials ranging
from heterogeneous solids, porous materials, nanofluids, and
ferrofluids. The model could explain the effective thermal
conductivity of not only the combination of solids but also
solid−fluid mixtures. The proposed theory could successfully
link the existing models for porous solid materials and
nanofluids as its special cases. The proposed model is verified against experimental data by simulating the theoretical equations
Ključne besede: thermal conductivity, generalised model, Sankar-Loeb model
Objavljeno v RUNG: 05.07.2022; Ogledov: 1206; Prenosov: 0
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38. Thermal diffusivity downscaling of molybdenum oxide thin film through annealing temperature-induced nano-lamelle formation: a photothermal beam deflection studyS. Soumya, Vimal Raj, Mohanachandran Nair Sindhu Swapna, Sankaranarayana Iyer Sankararaman, 2021, izvirni znanstveni članek Opis: The present work proposes a method of downscaling the thermal diffusivity (α)
of MoO3 thin films through annealing temperature-induced nano-lamelle formation. The
thermal diffusivity modification of the MoO3 films, prepared by the doctor blade method,
is investigated by the sensitive transverse photothermal beam deflection technique. The X-ray diffraction analysis confirms the structural phase transformation from monoclinic to
orthorhombic in the films annealed from 300 to 450 °C. The thermal induced anisotropy of
the film is evident from the variation of the morphology index and texture coefficient. The
field emission scanning electron microscopic analysis unveils the morphology modifications
from blocks to the nano-lamelle structure with layers of average thickness ~ 77 nm. The
thermal diffusivity measurement reveals a 53% reduction upon annealing the film to 450 °C.
The drastic reduction is achieved through the annealing temperature-induced nano-lamelle
formation and the phase transformation from monoclinic to orthorhombic in the MoO3 films.
Ključne besede: thermal diffusivity, molybdenum oxide, thin film, nano-lamelle, photothermal beam deflection
Objavljeno v RUNG: 04.07.2022; Ogledov: 1171; Prenosov: 26
 Povezava na celotno besedilo
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39. Concentration-dependent thermal duality of hafnium carbide nanofluid for heat transfer applications : a mode mismatched thermal lens studyVijayakumar Gokul, Mohanachandran Nair Sindhu Swapna, Vimal Raj, H. V. Saritha Devi, Sankaranarayana Iyer Sankararaman, 2021, izvirni znanstveni članek Opis: he mode mismatch dual-beam thermal lens technique is a sensitive tool for studying the nanofuids’ thermal difusivity in thermal engineering. The work reports
the low-temperature green synthesis of hafnium carbide (HfC) using rice four as a natural carbon precursor and its potential in heat transfer nanofuids by studying the concentration-dependent thermal difusivity. The structure characterisations confirm the formation of HfC, whose refractory nature is revealed through the high thermal stability observed in the thermogravimetric analysis. The Tauc plot analysis shows direct bandgap energy of 2.92 eV. The fuorescence study suggests bluish-pink emission with CIE coordinates (0.271, 0.263). The existence of the critical concentration of HfC in the nanofuid decides its suitability for heat transfer or heat trap applications indicating a concentration-dependent thermal duality. Thus, the study is signifcant as it overcomes the major drawbacks of the existing methods of the synthesis of refractory HfC, using toxic chemical and costly equipment for heat transfer applications.
Ključne besede: hafnium carbide, hydrothermal synthesis, rice flour, thermal lens spectroscopy
Objavljeno v RUNG: 04.07.2022; Ogledov: 1213; Prenosov: 0
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40. Thermal diffusivity of molybdenum oxide nanowire film: a photothermal beam deflection studyMohanachandran Nair Sindhu Swapna, 2021, izvirni znanstveni članek Opis: The paper reports the preparation of thin film with MoO3 nanowires (NWs) by the doctor blade method and the
study of its thermal diffusivity (α) by the sensitive photothermal beam deflection (PTD) method. When the Field
Emission Scanning Electron Microscopic and Atomic Force Microscopic analysis unveil its morphology as NW
bundles, the X-ray diffraction analysis reveals the structure to be orthorhombic. The NWs formed are of diameter
~ 20 nm and length up to 5 μm. The standardization of the transverse PTD setup is done by determining the
value of α of iron, which agrees well with literature reports. The thermal diffusivity of MoO3 NW film is obtained
as 0.0036 cm2
/s, which is 9.48% of its bulk counterpart. The reduction in the thermal diffusivity of NW makes it
a suitable candidate for thermoelectric applications.
Ključne besede: Nanowires
Molybdenum oxide
Photothermal beam deflection
Thermal diffusivity
Objavljeno v RUNG: 04.07.2022; Ogledov: 1222; Prenosov: 0
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