1. Recent Progress and Applications of Thermal Lens Spectrometry and Photothermal Beam Deflection Techniques in Chemical Analysis and Materials' CharacterizationMladen Franko, 2023, invited lecture at foreign university Abstract: Initially the theoretical background relevant to recent developments of thermal lens spectrometry (TLS) which include TLS detection in liquid chromatography and in microfluidic flow injection analysis (μFIA) and to non-contact and non-destructive characterization of composite materials by beam deflection spectrometry (BDS) is presented. The advantages and basic characteristics of the TLS and BDS techniques are illustrated by presenting applications such as the determination of free bilirubin in endothelial cells by HPLC-TLS, studies of diffusion in Taylor-type microfluidic flows by thermal lens microscopy (TLM), μFIA-TLM detection of microcystin-LR and Cr(VI) in waters, and by the dept profiling of multi-layered coatings of orthopaedic implants.
In the main part of the presentation the results of joint MU-UNG research are presented with emphasis on BDS and TLS characterisation of biocomposite materials from cellulose and chitosan or keratin with added Ag nanoparticles, sporopollenin capsules or antibiotics. The focus is on BDS determination of thermal parameters including thermal diffusivity and related properties relevant for medical applications, such as porosity and surface roughness, as well as on the TLS detection of Ag and other nanoparticles applied in studies of nanoparticle leaching from biocomposites.
Keywords: Optotermična spektrometrija, TLS, BDS, kemijska analiza, karakterizacija materialov, biokompoziti
Published in RUNG: 23.10.2023; Views: 1294; Downloads: 5
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3. Trajnostni biokompozitni materiali iz naravnih polimerov in njihova neporušna karakterizacija z optotermičnimi tehnikamiMladen Franko, other performed works Abstract: Predstavljene so osnove zelene sinteze novih biokompozitnih materialov iz kombinacij celuloze s hitosanom ali keratinom in sporopoleninom ter njihove protimikrobne lastnosti in adsorpcijske sposobnosti za čiščenje vode. Pomembna lastnost biokompozitov z vidika njihove uporabnosti je tudi poroznost, ki jo lahko določamo neporušno in nekontaktno s tehniko optotermičnega odlkona. Ta omogoča določevanje toplotne difuzivnosti materialov ter preko nje poroznosti, kot tudi globinske porazdelitve v material vgrajenih snovi, ki izboljšujejo njegove lastnosti.
Keywords: Biokompoziti, celuloza, hitosan, keratin sporopolenin, toplotna difuzivnost, poroznost, optotermična spektrometrija
Published in RUNG: 11.05.2023; Views: 2210; Downloads: 0
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4. Hemichrome Determination by Thermal Lensing with Polyethylene Glycols for Signal Enhancement in Aqueous SolutionsViktoriya Galimova, Mladen Franko, Mikhail Proskurnin, Mingqiang Liu, 2018, original scientific article Abstract: The thermal lens technique is proposed for the determination of total hemoglobin in the form of reversible hemichrome. The conditions were optimized (concentration of sodium dodecyl sulfate, 2 mM) to attain the maximum sensitivity with the use of polyethylene glycols as signal enhancers. For polyethylene glycols with molecular weights 1500–35000 Da in a concentration range of 5–15% w/w (5–25 mM), the influence on thermal lens signal enhancement was estimated. It is shown that the use of 5% w/w polyethylene glycol 2000 provides the maximum increase in the thermal lens enhancement factor (by 40%) in comparison with unmodified aqueous solutions. The detection limit of iron(II) tris(1,10-phenanthrolinate) as a model system is 60 nM. Under these conditions, the thermal lens detection limit of hemichrome is 10 nM, which shows a 15-fold enhancement compared to spectro- photometry. Modification of the medium with polyethylene glycols decreases the limit of detection of hemichrome determination by 15% in comparison with unmodified aqueous solutions due to better reproducibility for the range of concentrations from 0.02 to 0.9 μM.
Keywords: Hemoglobin, hemikrom, optotermična spektroskopija, etilenglikol, spektrometrija s toplotnimi lečami
Published in RUNG: 16.04.2018; Views: 4709; Downloads: 0
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