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1.
PHOTOTHERMAL-DEFLECTION SPECTROSCOPY FOR THE DETERMINATION OF THERMAL DIFFUSIVITY OF SOILS AND SOIL AGGREGATES
Mikhail A. Proskurnin, Dorota Korte, O.B. Rogova, D.S. Volkov, Mladen Franko, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Ključne besede: PHOTOTHERMAL-DEFLECTION SPECTROSCOPY, THERMAL DIFFUSIVITY, soil, soil aggregates
Objavljeno: 30.08.2017; Ogledov: 2947; Prenosov: 0
.pdf Polno besedilo (12,87 MB)

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Through-plane and in-plane thermal diffusivity determination of graphene nanoplatelets by photothermal beam deflection spectrometry
Stefano Bellucci, Hanna Budasheva, Behnaz Abbasgholi N. Asbaghi, Humberto Cabrera, Dorota Korte, 2021, izvirni znanstveni članek

Opis: In this work, in-plane and through-plane thermal diffusivities and conductivities of a freestanding sheet of graphene nanoplatelets are determined using photothermal beam deflection spectrometry. Two experimental methods were employed in order to observe the effect of load pressures on the thermal diffusivity and conductivity of the materials. The in-plane thermal diffusivity was determined by the use of a slope method supported by a new theoretical model, whereas the through-plane thermal diffusivity was determined by a frequency scan method in which the obtained data were processed with a specifically developed least-squares data processing algorithm. On the basis of the determined values, the in-plane and through-plane thermal conductivities and their dependences on the values of thermal diffusivity were found. The results show a significant difference in the character of thermal parameter dependence between the two methods. In the case of the in-plane configuration of the experimental setup, the thermal conductivity decreases with the increase in thermal diffusivity, whereas with the through-plane variant, the thermal conductivity increases with an increase in thermal diffusivity for the whole range of the loading pressure used. This behavior is due to the dependence of heat propagation on changes introduced in the graphene nano-platelets structure by compression.
Najdeno v: ključnih besedah
Ključne besede: graphene nanoplatelets, thermal diffusivity, thermal conductivity, photothermal spectrometry
Objavljeno: 30.11.2021; Ogledov: 601; Prenosov: 26
URL Polno besedilo (0,00 KB)
Gradivo ima več datotek! Več...

4.
Investigations of the Thermal Parameters of Hybrid Sol–Gel Coatings Using Nondestructive Photothermal Techniques
Łukasz Chrobak, Dorota Korte, Hanna Budasheva, Miroslaw Maliński, Peter Rodič, Ingrid Milošev, Sylwia Janta-Lipińska, 2022, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...g, photothermal radiometry, photothermal beam deflection spectrometry, thermal diffusivity, thermal conductivity...
Ključne besede: hybrid sol–gel coatings, non-destructive testing, photothermal radiometry, photothermal beam deflection spectrometry, thermal diffusivity, thermal conductivity
Objavljeno: 03.06.2022; Ogledov: 184; Prenosov: 5
.pdf Polno besedilo (1,36 MB)

5.
Weathering induced morphological modification on the thermal diffusivity of natural pyrrhotite
Mohanachandran Nair Sindhu Swapna, V. Gokul, Vimal Raj, R. Manu Raj, S. N. Kumar, Sankaranarayana Iyer Sankararaman, 2021, izvirni znanstveni članek

Opis: Natural pyrrhotites have gained significant attention due to their interesting electronic, antimicrobial, and chemical properties. The present work attempts to explore the morphology-induced modifications in the thermal characteristics of natural pyrrhotite due to ageing. The morphological, elemental, structure, optical, and thermal characterisations help in understanding the effect of ageing. The effects of five years of ageing of the sample are (i) Field Emission Scanning Electron Microscopic analysis reveals a morphological transformation from flakes to agglomerated powder, (ii) elemental analyses suggest the ageing induced compositional modification (iii) the Tauc plot analysis shows a bandgap energy modification from 1.46 eV to 1.92 eV, (iv) X-ray Diffraction (XRD), Fourier Transform Infrared, and X-ray photoelectron spectroscopic studies affirm the formation of oxy-hydroxides (v) the XRD data indicates an increase of dislocation density, and (vi) Photoluminescence study shows a deep violet emission evidenced through the CIE plot. The study by the thermal lens technique shows a lowering of thermal diffusivity study by 23%, due to the morphological modifications, adsorbed/chemisorbed hydroxyl groups, and the formation of secondary compounds due to oxidation and weathering. The phonon boundary scattering, weathering induced smaller grain size, reduced phonon mean free path, and point defects also account for the lowering of the thermal diffusivity value and thereby influencing its properties.
Najdeno v: ključnih besedah
Ključne besede: pyrrhotite, thermal diffusivity, thermal lens, ageing, morphology
Objavljeno: 30.06.2022; Ogledov: 115; Prenosov: 1
.pdf Polno besedilo (1,82 MB)
Gradivo ima več datotek! Več...

6.
Absolute Porosity Analysis in Carbon Allotropic Nanofluids: A Sankar–Swapna Model Approach
SANKARARAMAN S, SREEJYOTHI S, SWAPNA MOHANACHANDRAN NAIR SINDHU, 2020, izvirni znanstveni članek

Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...the material. The porosity greatly influences the thermal diffusivity of a material. The manuscript is the...
Ključne besede: absolute porosity, Sankar–Swapna model, thermal diffusivity, thermal lens, thermal conductivity
Objavljeno: 04.07.2022; Ogledov: 76; Prenosov: 0
.pdf Polno besedilo (1,96 MB)

7.
Tuning the thermal diffusivity of the seed matter for enhanced biosynthesis: A thermal lens study
SANKARARAMAN S, SWAPNA MOHANACHANDRAN NAIR SINDHU, 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.
Najdeno v: ključnih besedah
Ključne besede: seed matter, thermal diffusivity, thermal lens, carbon nanoparticle, soot
Objavljeno: 04.07.2022; Ogledov: 75; Prenosov: 0
.pdf Polno besedilo (2,68 MB)

8.
Allotropic transformation instigated thermal diffusivity of soot nanofluid: Thermal lens study
SANKARARAMAN S, RAJ VIMAL, SWAPNA MOHANACHANDRAN NAIR SINDHU, 2019, izvirni znanstveni članek

Opis: This paper employs the sensitive single-beam thermal lens technique for analyzing the thermal behavior of gasoline soot containing allotropes of carbon by preparing its nanofluid (NF). The soot, annealed at different temperatures up to 400 ○C (the samples), used for preparing the NF, is found to enhance the thermal diffusivity (α) up to 95% without changing the solid volume fraction, suggesting its possible use in coolants. The thermal induced modifications are understood from the field emission scanning electron microscopic, X-ray diffraction (XRD),thermogravimetric, and Raman spectroscopic analyses. The variation of α of the sample is found to exhibit similar variations observed in XRD and Raman spectroscopic analyses. The study stresses the significance of the optimum temperature (300 ○C) for the soot NF above which morphological and structural modifications may lead to thermal energy trapping rather than dissipation or cooling.
Najdeno v: ključnih besedah
Ključne besede: petrol soot, thermal lens, thermal diffusivity
Objavljeno: 04.07.2022; Ogledov: 95; Prenosov: 0
.pdf Polno besedilo (3,08 MB)

9.
Pharmacological application of thermal Lens technique - A thermal diffusivity study
SWAPNA MOHANACHANDRAN NAIR SINDHU, 2018, izvirni znanstveni članek

Opis: The photothermal phenomenon has emerged as a potential tool for the nondestructive evaluation of thermal and optical properties of materials. Thermal analysis of drugs is an unavoidable part of preformulation study, as temperature variations can induce structural changes of the constituents of drugs. Techniques based on photothermal phenomena are highly sensitive, as only the absorbed radiation contributes to the signal. Periodic illumination and subsequent nonradiative de-excitation generate thermal lens signals of various types within and around the sample. Variation of thermal diffusivity with a concentration of the commonly used drug terbutaline is studied through the single-beam thermal lens technique. The ultraviolet–visible spectrum of the drug shows strong absorption around 500 nm, which suggests the possible wavelengths that can be used for the study. It is found that concentration of the drug in liquid form decides its thermal stability, as its thermal diffusivity varies with concentration. The study gives information about the optimum value for the concentration of the drug noted above for which the chance of thermal stability is high.
Najdeno v: ključnih besedah
Ključne besede: thermal lens, thermal diffusivity, pharmacology, drug
Objavljeno: 30.06.2022; Ogledov: 123; Prenosov: 0
.pdf Polno besedilo (1,47 MB)

10.
Development of Zinc Oxide-Multi-Walled Carbon Nanotube hybrid nanofluid for energy-efficient heat transfer application: A thermal lens study
SWAPNA MOHANACHANDRAN NAIR SINDHU, 2021, izvirni znanstveni članek

Opis: This paper addresses the need for developing an energy-efficient hybrid nanofluid with zinc oxide–multi-walled carbon nanotube (ZnO-MWCNT) for overcoming the bottleneck of efficient heat transfer in thermal systems. The concentration-dependent thermal diffusivity modifications are analyzed using the highly sensitive mode mismatched thermal lens technique. The hybrid composite is prepared by the solid-state mixing and annealing of a pure multi-walled carbon nanotube (MWCNT) and zinc oxide (ZnO), synthesized by the solution combustion method. The composite formation is studied by structural, morphological, and optical characterization techniques. Among the three nanofluids ZnO, MWCNT, and ZnO-MWCNT, the composite exhibits a drastic enhancement in thermal diffusivity at a lower solid volume fraction of 0.047 mg/ml containing 0.009 mg/ml of MWCNT. All the nanofluids show an optimum concentration beyond which the thermal diffusivity decreases with the nanoparticle concentration. Thus, this study suggests the potential application of ZnO-MWCNT hybrid nanofluids in thermal system design to enhance internal combustion engines' efficiency during cold-start.
Najdeno v: ključnih besedah
Povzetek najdenega: ...transfer in thermal systems. The concentration-dependent thermal diffusivity modifications are analyzed using the highly sensitive...
Ključne besede: Zinc Oxide, MWCNT, hybrid nanofluid, thermal lens, diffusivity, engine efficiency
Objavljeno: 30.06.2022; Ogledov: 121; Prenosov: 0
.pdf Polno besedilo (2,44 MB)

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