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27. 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: 1977; Prenosov: 0
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28. 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: 2077; Prenosov: 0
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29. Laser-induced thermal lens study of the role of morphology and hydroxyl group in the evolution of thermal diffusivity of copper oxideRiya Sebastian, Mohanachandran Nair Sindhu Swapna, Vimal Raj, Sankaranarayana Iyer Sankararaman, 2022, izvirni znanstveni članek Opis: The paper explores the evolution of thermal behavior of the material by studying the variations in thermal diffusivity
using the single beam thermal lens (TL) technique. For this purpose, the decomposition of Cu(OH)2 into CuO is studied in a
time range up to 120 h, by subjecting the sample to morphological, structural, and spectroscopic characterizations. The time
evolution of thermal diffusivity can be divided into three regions for demonstrating the dynamics of the reaction. When the
reaction is complete, the thermal diffusivity is also found to be saturated. In addition to the morphological modifications,
from rods to flakes, the variations in the amount of hydroxyl group are attributed to be responsible for the enhancement
of base fluid’s thermal diffusivity by 165%. Thus the study unveils the role of hydroxyl groups in the thermal behavior of
CuO.
Ključne besede: thermal diffusivity, CuO, thermal lens, morphology, hydroxyl group
Objavljeno v RUNG: 04.07.2022; Ogledov: 1880; Prenosov: 0
Gradivo ima več datotek! Več... |
30. Acclimatisation through thermal diffusivity tuning of coconut oil – A mode mismatched dual-beam thermal lens studyMohanachandran Nair Sindhu Swapna, 2022, izvirni znanstveni članek Opis: Background: Ayurvedic medicinal oils traditionally prepared by blending herbal extracts in different
compositions are commonly used for treatment and improving health. The estimation of the thermal
properties of medicinal oils is essential for practical applications.
Objective: The present work aims to expound the ability of medicinal oils for the acclimatization of body
temperature by determining its thermal diffusivity and thereby providing a validation to the traditional
knowledge.
Materials and methods: The medicinal oils are prepared by incorporating black pepper (Piper nigrum),
aloe vera (Aloe barbadensis), hibiscus bud (Hibiscus rosa-sinensis) and Ocimum sanctum in coconut oil
base. The samples are subjected to thermal diffusivity study using the mode-mismatched dual-beam
thermal lens technique.
Results: The study reveals that the incorporation of black pepper (Piper nigrum), having hot potency
(Ushna veerya), to the base fluid lowers the thermal diffusivity value, suggesting its potential in heat-trapping. The addition of aloe vera (Aloe barbadensis), hibiscus bud (Hibiscus rosa-sinensis), and
O. sanctum dissipates heat energy quickly, thus increases the thermal diffusivity of coconut oil revealing a
cold potency (Sheeta veerya). The study provides a validation for traditional knowledge and delineates
the possiblity of thermal diffusivity tuning of the base fluids.
Conclusion: The thermal diffusivity tuning through incorporation of herbal extracts can effectively be
used to acclimatize the human body temperature with the surroundings. A higher thermal diffusivity
value induces a cooling effect and the lower value causes heating effect. This, opens up the possibility of
using thermally tuned oils depending on climate and geographical location.
Ključne besede: Ayurveda, Acclimatization, Medicinal oils, Thermal lens spectroscopy
Thermal diffusivity
Objavljeno v RUNG: 04.07.2022; Ogledov: 1870; Prenosov: 0
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