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Optical emission diagnosis of carbon nanoparticle incorporated chlorophyll for sensing applications
Swapna Mohanachandran Nair Sindhu, RAJ VIMAL, SARITHA DEVI H V, Sankararaman S, 2019, izvirni znanstveni članek

Opis: Chlorophyll fluorescence (Chl F) is widely used in sensing applications to understand terrestrial vegetation and environmental and climatic variations. The increasing rates of industrialization and carbon emission from internal combustion engines (ICEs) pose a threat to sustainable development. This study analyses the impact of carbon nanoparticles (CNPs) from ICEs on the optical absorption and fluorescence emission of leaf pigments. Leaf pigments without and with CNPs were subjected to UV-visible and photo-luminescence (PL) spectroscopy analyses. The field emission scanning electron microscopy and high-resolution transmission electron microscopy images of CNPs showed their morphology. The Jablonski diagram of the CNP-incorporated chlorophyll system helped in understanding the fluorescence emission,internal conversion, and the exchange of energy between them. The variations in (i) total chlorophyll, (ii) optical absorbance by total chlorophyll, (iii) PL emission peak (at 675 nm and 718 nm) intensities for different excitation wavelengths, and (iv) normalized absorbance at the PL emission peaks with different CNP concentrations were analysed by dividing into three regions. In Region I (0–0.625 mg ml−1 ), the radiative component dominated the nonradiative component as a result of energy transfer from CNPs to chlorophyll. In Region II (0.625–1.2 mg ml−1 ), the increase in CNP concentration initiated diffusion into chloroplasts, resulting in the increase in the nonradiative part of total energy and decrease in PL peak intensity. In Region III (1.2–2.5 mg ml−1 ), the energy absorbed by the CNPs dissipated more nonradiatively, leading to a slow rate of increase in the radiative part. The visual response of PL emission, color purity, and the distribution of the emitted energy over the spectrum studied with the help of CIE plots, power spectrum, and confocal fluorescence microscopy revealed the fluorescence emission in the red region. This study suggests the possibility of employing Chl F in agricultural, environmental, and biological fields for sensing applications.
Ključne besede: carbon nanoparticle, optical emission, fluorescence
Objavljeno v RUNG: 05.07.2022; Ogledov: 437; Prenosov: 0
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Carbon nanoparticles assisted energy transport mechanism in leaves: A thermal lens study
Swapna Mohanachandran Nair Sindhu, 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: 466; Prenosov: 0
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Tuning the thermal diffusivity of the seed matter for enhanced biosynthesis: A thermal lens study
Swapna Mohanachandran Nair Sindhu, Sankararaman S, 2020, izvirni znanstveni članek

Opis: 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.
Ključne besede: seed matter, thermal diffusivity, thermal lens, carbon nanoparticle, soot
Objavljeno v RUNG: 04.07.2022; Ogledov: 472; Prenosov: 0
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Fractal and spectroscopic analysis of soot from internal combustion engines
Swapna Mohanachandran Nair Sindhu, SARITHA DEVI H V, RAJ VIMAL, Sankararaman S, 2018, izvirni znanstveni članek

Opis: 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.
Ključne besede: Fractals, internal combustion engine, efficiency, soot, carbon nanoparticle
Objavljeno v RUNG: 30.06.2022; Ogledov: 513; Prenosov: 0
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Boron‑rich boron carbide from soot : a low-temperature green synthesis approach
Mohanachandran Nair Sindhu Swapna, H. V. Saritha Devi, Sankaranarayana Iyer Sankararaman, 2020, izvirni znanstveni članek

Opis: Boron carbide is a promising super-hard semiconducting material for refractory applications ranging from the nuclear industry to spacecraft. The present work is the frst report of not only turning futile soot, containing carbon allotropes in varying composition, into boron-rich boron carbide (BC), but also developing it by a low-cost, low-temperature, and green synthesis method. The BC synthesised from gingelly oil soot is subjected to structural, morphological, and optical characterisations. The feld emission scanning electron microscope shows beautiful fower-like morphology, and the thermogravimetric analysis reveals the high-temperature stability of the sample synthesised. The Tauc plot of the sample indicates a 2.38 eV direct bandgap. The formation of BC and boron-rich carbide evidenced by X-ray difraction studies is confrmed through Raman and Fourier transform infrared spectroscopic signatures of B–C and C–B–C bonds. The fuorescence, power spectrum, and CIE analyses carried out suggest the blue light emission for excitation at 350 nm
Ključne besede: boron carbide, soot, carbon nanoparticle, refractory, allotropes, green synthesis
Objavljeno v RUNG: 30.06.2022; Ogledov: 485; Prenosov: 0
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