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Stable carbon isotope analysis of selected halocarbons at parts per trillion concentration in an urban location
M Iqbal Mead, M Anwar H Khan, Ian D Bull, Iain R White, Graham Nickless, Dudley E Shallcross, 2008, original scientific article

Abstract: ∂13C values of a suite of halocarbons have been determined in an urban background site in Bristol, UK. A novel mobile preconcentration system, based on the use of multi-adsorbent sample tubes, has been developed for trapping relatively large-volume air samples in potentially remote areas. An Adsorption Desorption System-Gas Chromatography-Electron Capture Detector was used to measure the mixing ratios of the selected halocarbon species, while a Gas ChromatographyCombustionIsotope Ratio Mass Spectrometer was used to determine ∂13C values. For the species with strong local sources, the variation of isotope ratios has been observed over the experimental period. Some of the results reported in the present study differ from previously reported values and reasons for this are discussed. The reporting of different ∂13C values for selected halocarbons from different areas in the present study suggests that ∂13C values may be used to determine the relative magnitudes of anthropogenic and biogenic sources.
Found in: ključnih besedah
Summary of found: ...Adsorption Desorption System (ADS), Automated Thermal Desorber (ATD), Electron Capture Detector (ECD), Gas... Bristol, UK. A novel mobile preconcentration system, based on the use of multi-adsorbent sample...
Keywords: Adsorption Desorption System (ADS), Automated Thermal Desorber (ATD), Electron Capture Detector (ECD), Gas Chromatography (GC), Isotope Ratio Mass Spectrometry (IRMS)
Published: 18.07.2019; Views: 2395; Downloads: 0
.pdf Fulltext (227,35 KB)

Soot effected sample entropy minimization in nanofluid for thermal system design
Sankaranarayana Iyer Sankararaman, K. Satheesh Kumar, Vimal Raj, Mohanachandran Nair Sindhu Swapna, 2020, original scientific article

Abstract: The present work suggests a method of improving the thermal system efficiency, through entropy minimisation, and unveils the mechanism involved by analysing the molecular/particle dynamics in soot nanofluids (SNFs) using the time series, power spectrum, and wavelet analyses of the thermal lens signal (TLS). The photothermal energy deposition in the SNF lowers the refractive index due to the temperature rise. It triggers the particle dynamics that are investigated by segmenting the TLS and analysing the refractive index, phase portrait, fractal dimension (D), Hurst exponent (H), and sample entropy (SampEn). The wavelet analysis gives information about the relation between the entropy and the frequency components. When the phase portrait analysis reflects the complex dynamics from region 1 to 2 for all the samples, the SampEn analysis supports it. The decreasing value of D (from 1.59 of the base fluid to 1.55 and 1.52) and the SampEn (from 1.11 of the base fluid to 0.385 and 0.699) with the incorporation of diesel and camphor soot, indicate its ability to lower the complexity, randomness, and entropy. The increase of SampEn with photothermal energy deposition suggests its relation to the thermodynamic entropy (S). The lowering of thermal diffusivity value of the base fluid from 1.4 × 10−7 m2/s to 1.1 × 10−7 and 0.5 × 10−7 m2 /s upon diesel and camphor soot incorporation suggests the heat-trapping and reduced molecular dynamics in heat dissipation.
Found in: ključnih besedah
Keywords: soot, entropy, thermal system, photothermal, time series, nanofluid, fractal
Published: 30.06.2022; Views: 506; Downloads: 0
.pdf Fulltext (2,27 MB)

Recent Progress and Applications of Thermal Lens Spectrometry and Photothermal Beam Deflection Techniques in Environmental Sensing
Dorota Korte, Mojca Žorž Furlan, Hanna Budasheva, Mingqiang Liu, Leja Goljat, Mladen Franko, 2023, original scientific article

Abstract: This paper presents recent development and applications of thermal lens microscopy (TLM) and beam deflection spectrometry (BDS) for the analysis of water samples and sea ice. Coupling of TLM detection to a microfluidic system for flow injection analysis (µFIA) enables the detection of microcystin-LR in waters with a four samples/min throughput (in triplicate injections) and provides an LOD of 0.08 µg/L which is 12-times lower than the MCL for microcystin-LR in water. µFIA-TLM was also applied for the determination of total Fe and Fe(II) in 3 µL samples of synthetic cloudwater. The LODs were found to be 100 nM for Fe(II) and 70 nM for total Fe. The application of µFIA-TLM for the determination of ammonium in water resulted in an LOD of 2.3 µM for injection of a 5 µL sample and TLM detection in a 100 µm deep microfluidic channel. For the determination of iron species in sea ice, the BDS was coupled to a diffusive gradient in the thin film technique (DGT). The 2D distribution of Fe(II) and total Fe on DGT gels provided by the BDS (LOD of 50 nM) reflected the distribution of Fe species in sea ice put in contact with DGT gels.
Found in: ključnih besedah
Summary of found: ...Coupling of TLM detection to a microfluidic system for flow injection analysis (µFIA) enables the...
Keywords: thermal lens microscopy, beam deflection spectrometry, microfluidic system, microcystin-LR detection, iron species determination, ammonium detection
Published: 03.01.2023; Views: 269; Downloads: 14
.pdf Fulltext (2,90 MB)

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