41. Photodegradation mechanisms of reactive blue 19 dye under UV and simulated solar light irradiationZeinab Ebrahimpour, Olena Pliekhova, Humberto Cabrera, Mahmoud Abdelhamid, Dorota Korte, Komlan Segbéya Gadedjisso-Tossou, Joseph J. Niemela, Urška Lavrenčič Štangar, Mladen Franko, 2021, original scientific article Keywords: reactive blue 19, photocatalytic, photosensitization, thermal lens, UV-Vis
Published in RUNG: 02.02.2021; Views: 2512; Downloads: 0
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43. Implementation of high performance liquid chromatography coupled to thermal lens spectrometry (HPLC‑TLS) for quantification of pyranoanthocyanins during fermentation of Pinot Noir grapesJelena Topič Božič, Lorena Butinar, Natka Ćurko, Karin Kovačević Ganić, Branka Mozetič Vodopivec, Dorota Korte, Mladen Franko, 2020, original scientific article Abstract: In this work high performance liquid chromatography coupled to thermal lens spectrometry (HPLC-TLS) was applied for monitoring of vinylphenolic pyranoanthocyanins formation during the fermentation of Pinot Noir wines. Vinylphenolic pyranoanthocyanins are wine pigments, present in low concentrations, but very important for wine colour stability.
Fermentation process was conducted with four different yeast strains, used as starters, either in sequential fermentation of non-Saccharomyces with S. cerevisiae yeast or as single fermentation with S. cerevisiae yeasts in order to test the applicability of developed method for monitoring of selected compounds in real wine fermentation experiments. The
developed HPLC-TLS method showed higher sensitivity compared to HPLC coupled to diode array detection (DAD) technique for particular wine colour compounds. Obtained limits of detection (LODs), were 6- and 22-times lower in comparison to HPLC–DAD in gradient and isocratic elution mode, respectively, whereas limits of quantification (LOQs)
5 and 18-times lower. Lower LODs enabled earlier observation of vinylphenolic pyranoanthocyanins formation during fermentation (already at day 7) in the case of HPLC-TLS method in gradient mode, while by using HPLC–DAD in gradient elution mode the formation of vinylphenolic pyranoanthocyanins was noticed only after 12 days of fermentation.
Keywords: Thermal lens spectrometry (TLS), High performance liquid chromatography (HPLC), Pyranoanthocyanins, Wine, Yeasts
Published in RUNG: 18.06.2020; Views: 3305; Downloads: 0
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44. Thermal and Elastic Characterization of Nanostructured Fe2O3 Polymorphs and TiO2‑Coated Fe2O3 Using Open Photoacoustic CellN Jovančić, D K Markushev, Dragan D. Markushev, S M Aleksić, D S Pantić, Dorota Korte, Mladen Franko, 2020, original scientific article Keywords: Elastic, Nanostructure, Photoacoustic, Polymorphs, Thermal · TiO2-coated Fe2O3
Published in RUNG: 19.05.2020; Views: 2748; Downloads: 0
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45. Thermal Effusivity Investigations of Solid Thermoelectrics Using the Front Photopyroelectric DetectionCarmen Tripon, Dorin Dadarlat, Katalin Kovacs, Victor Petru Tosa, Mladen Franko, 2020, original scientific article Abstract: The front photopyroelectric configuration (FPPE), making use of air as a coupling
fluid between the sample and sensor, was applied to measure the thermal effusivity of
some solid thermoelectric materials. The investigated samples were ZnO, CuCrO2,
Cu4Sn7S16,
TiS3
and two samples of high manganese silicide (HMS) thermoelectric
materials. Most of these materials are porous and consequently, the classical PPE
method, making use of standard coupling fluids between sensor and sample, cannot
be used due to the fact that the coupling fluid penetrates inside the sample and leads
to incorrect results. With this work we extend (to thermoelectric solids) the area of
application of a method, recently proposed by Salazar et al. (Measurement 121: 96,
2018). Experimentally, the thermal effusivity is obtained from a multi-parametric
fit of the phase of the FPPE signal as a function of the modulation frequency (with
sample’s thermal effusivity, thickness of the sensor-sample air gap and heat losses
by convection and radiation, as fitting parameters). It was demonstrated that, in some
particular cases, the three parameters are independent and consequently, the solution
of the fit is unique. Where possible, the obtained results have been compared with
data from the literature and good agreement was found.
Keywords: Front photopyroelectric configuration (FPPE), Solid thermoelectrics, Thermal effusivity
Published in RUNG: 02.05.2020; Views: 2696; Downloads: 0
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47. Determination of Iron in Environmental Water Samples by FIA-TLSMiha Tomšič, Leja Goljat, Hanna Budasheva, Dorota Korte, Arne Bratkič, Mladen Franko, 2019, original scientific article Abstract: The determination of low concentration of iron in natural waters can be difficult due to the complexity of natural water, but primarily because it requires preconcentration of the sample with solvent extraction. In this work we report on results of thermal lens spectrometry (TLS) coupled to flow injection analysis (FIA) as a highly sensitive FIA-TLS method of iron detection. The concentration of iron redox species was determined using 1,10-phenanthroline (PHN), that forms stable complexes with Fe(II) ions which are characterized by an absorption maximum at 508 nm. The TLS system using a 633 nm probe laser and 530 nm pump laser beam was exploited for on-line detection in flow injection analysis, where a PHN solution was used as the carrier solution for FIA. The concentration of the complexing agent affects the quality of the TLS signal, and the optimal concentration was found at 1 mM PHN. The achieved limits of detection (LODs) for Fe(II) and total iron were 33 nM for Fe(II) and 21 nM for total iron concentration. The method was further validated by determining the linear concentration range, specificity in terms of analytical yield and by determining concentration of iron in a water sample from a local water stream.
Keywords: Flow injection analysis, iron concentration, thermal lens spectroscopy
Published in RUNG: 18.12.2019; Views: 3257; Downloads: 105
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48. A multi-thermal-lens approach to evaluation of multi-pass probe beam configuration in thermal lens spectrometryHumberto Cabrera, Leja Goljat, Dorota Korte, Ernesto Marin, Mladen Franko, original scientific article Abstract: In this work, a recently proposed thermal lens instrument based on multi-pass probe beam concept is investigated and described as a multi-thermal-lens equivalent system. A simulation of the photothermal lens signal formation in a multi-thermal-lens equivalent configuration of the system is performed and validated by comparing the experimental signals of single, dual and ten-pass configurations to theoretically calculated values. The theoretically predicted enhancement of the signal is 9 to 10-fold for a weak thermal lens when comparing the ten-pass configuration with the conventional single-pass thermal lens system. Experimentally achieved signal enhancement in the ten-pass system is 8.3 for pure ethanol sample and between 8 and 9 for solutions with different concentrations of the Fe(II) - 1,10-Phenanthroline complex. Additionally, a value of 9.1 was calculated as the ratio of the slopes of the calibration lines obtained using the ten-pass and single-pass configurations. The achieved limit of detection for determination of Fe(II), in the ten-pass configuration, was 0.4 µgL-1, with a relative standard deviation around 4.5%, which compares favorably with previously reported results for TLS determination of Fe(II) in thin samples using low excitation power. For the multi-pass configuration the linear range of measurement is reduced when compared to the single-pass configuration. This is explained by the theoretical analysis of the photothermal signal under multi-pass condition, which shows the important contribution of the nonlinear term in the theoretical expression for the photothermal signal. The ten-pass configuration, which is presented and validated experimentally for the first time, offers important signal enhancement needed in recently developed TLS instruments with tunable, low power excitation sources.
Keywords: Thermal lens spectrometry, Photothermal detection, Trace determination, Chemical sensor
Published in RUNG: 10.12.2019; Views: 3225; Downloads: 0
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50. Quantitative detection of Microcystis aeruginosa in fresh water using single domain antibodies (VHHs)Gbenga Folorunsho Oginni, Sandra Oloketuyi, Elisa Mazzega, Mladen Franko, Hanna Budasheva, Dorota Korte, Ario De Marco, published scientific conference contribution abstract Keywords: thermal lens spectrometry, nanobodies, fluobodies, cyanobacteria
Published in RUNG: 18.11.2019; Views: 3606; Downloads: 122
Full text (15,09 KB) |
