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    A comparative analysis of ten milk samples with differential scanning calorimetry and Fourier transform infrared spectroscopy
    (2023) Dinç, Bircan; Üstünsoy, Recep; Ertaş, Tahsin; Şen, Emine
    Milk proteins occupy a prominent place in the nutrition of adults and children. Generally, some commercial dairy contains proteins, lactose, other sugar derivatives, and additives. The propor- tions of the components that make up the milk are different in commercial milk. For this reason, analyzing milk correctly is essential for determining these contents. In this research, analyses of the milk were made by taking differential scanning calorimetry measurements (DSC), and Fourier transform infrared spectrophotometer (FTIR) measurements. Specific heat values and specific values of temperature peaks were examined for ten kinds of milk. DSC curves revealed triacyl- glycerol dissolution, lactose crystallization, and protein denaturation peaks. Wide variations were observed with the same fat content from 10 milk powders. Most characteristic peaks were not observed when the samples were re-measured after a year at -20°C. The powder samples were compared in terms of protein, fat, lactose content, whey protein casein, and caseinate contents according to differences in FTIR spectra. The FTIR results confirm the DSC curves for most of the analyzed milk types.
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    Öğe
    Investigation of the degree of monomer conversion in dental composites through various methods: an in vitro study
    (2024) Üçüncü, Musa Kazım; Çeliksöz, Özge; Şen, Emine; Yücel, Yasemin Yücel; Dinç, Bircan
    The degree of monomer conversion (DC) values of three different dental composites were examined using three different methods: surface microhardness (ratio of bottom/top), Fourier-transform infrared (FT-IR), and differential scanning calorimetry (DSC). Two of the dental composites included in the study were nanohybrid (Dentsply Neo Spectra ST HV and Omnichroma), and one was a microhybrid-labeled newly marketed composite containing nanoparticles (Dentac Myra). Composite discs were prepared according to the methodology for all methods and analyzed (2 mm thickness x 5 mm diameter). Surface microhardness values were measured in Vickers Hardness Number (VHN), while FT-IR and DSC values were obtained in percentage (%). Significant differences were observed in both bottom/top surface microhardness values and DC values obtained from FT-IR. However, there was no statistical difference in the ratio of bottom/top microhardness values. Neo Spectra ST HV exhibited superior performance in both microhardness and monomer conversion compared to the other two composites. Newly marketed Myra showed values close to Omnichroma. It was found that the values obtained by the DSC method were parallel to those obtained by FT-IR. In conclusion, the structure of dental composites leads to different mechanical properties. Additionally, DSC measurements and FTIR spectra were found to be complementary techniques for characterizing monomer conversion values.
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    Öğe
    Toxicity of short multi-walled carbon nanotubes in caenorhabditis elegans
    (Taylor&Francis, 2021) Dinç, Bircan; Şen, Emine
    Carbon nanotubes have become widely used due to their superior physiochemical properties, and so knowledge of their toxicity has become important. In this study, the toxic effects of nanotubes on Caenorhabditis elegans have been investigated. Multi-walled carbon nanotubes were characterized by transmission electron microscopy and particle size analysis. Upon exposure to the nanotubes at concentrations of 100 to 500 mg/L for 3 to 15 days, numbers and body lengths of the nematodes were not altered, but body thickness was raised and body movements were slightly decreased. A new type of toxicity-reproduction assay was performed to see the effect of multiwalled carbon nanotubes. The circular-form aggregation of starved larvae was counted. The number of aggregations was reduced with the increasing nanotube concentration by 27%. The concentration-dependent reduction was confirmed by counting the eggs in a single worm which demonstrated the negative effect of multi-walled carbon nanotubes on reproduction when the nematodes were subjected to prolonged exposure.