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Aug 2023 DOI 10.14302/issn.2377-2549.jndc-23-4461
Kripal RamCorresponding author
The synthesis of II-VI semiconductor nanocrystals doped with transition metal ions is particularly difficult. In the case of manganese doped CdSe nanocrystals produced via chemical route it is necessary to achieve small incorporation of manganese ions. The incorporation of manganese ions in CdSe nanocrystals has been confirmed by the study of Energy Dispersive Spectroscopy, Photoluminescence and Electron Paramagnetic Resonance spectra. The CdSe nanocrystals have cubic structure, the average crystallite size lies between 3-6 nm and increases with the variation of doping concentration of Mn2+ ions as characterized by X-ray diffraction. The structural properties of CdSe semiconductor nanocrystals are also studied by High Resolution Transmission Electron Microscopy, Scanning Electron Microscopy and UV- Visible Absorption Spectroscopy. The energy band gaps have been determined by UV/V is absorption study with the help of Tauc plot and are 2.54 eV, 2.27 eV and 2.24 eV as concentration of Mn2+ions in CdSe semiconductor nanocrystals increases from 0% to 0.75%. The crystallite size is also obtained from the UV-Visible absorption study; this varies from 1.69 to 1.78 nm with increase of Mn2+ concentration from 0% to 0.75% which is in agreement with X-ray diffraction result. Further, the magnetic and electronic properties of Mn2+ doped CdSe nanocrystals are studied using EPR spectra and the values of g factor, second-rank axial zero-field splitting parameter D and hyperfine parameter A are calculated. EPR measurements reveal that the dopant ions are incorporated in CdSe semiconductor nanocrystals.
Sep 2019 DOI 10.14302/issn.2471-2140.jaa-19-2997
Shumaev K.B.Corresponding author
National Medical Research Centre for Cardiology, Moscow, Russia.
The paper explores the formation of a-oxoaldehydes during the interaction of glucose metabolites with hydroxyl or alkoxyl radicals. Hydroxyl radicals were generated under radiolysis of aqueous solutions, and alkoxyl radicals (t-BuO) were obtained in the model system tert-butyl hydroperoxide/Fe2+. High-performance liquid chromatography revealed that methylglyoxal was one of the organic products resulting from t-BuO-induced transformations of fructose-1,6-bisphosphate under hypoxic conditions. The interaction of lysine and methylglyoxal one of the main targets of a-oxoaldehydes in proteins was also studied. As chemiluminescence and EPR spectroscopy demonstrated, this reaction generates a methylglyoxal anion radical, a cation-radical of methylglyoxal dialkylamine and a superoxide anion radical. EPR signal of methylglyoxal-derived free radicals was observed in hypoxia, whereas only the trace amounts of these free radicals were recorded in the aerated reaction medium.
Feb 2018 DOI 10.14302/issn.3070-2313.jeh-17-1756
Tamer GoncaCorresponding author
Division of Endocrinology and Metabolism, Department of Internal Medicine, Medeniyet University, Göztepe Training and Research Hospital, Istanbul.
Objective We aimed to evaluate β-cell function of type 1 diabetic patients (T1DP)s based on fasting and stimulated C-peptide levels. Material and methods Study included 135 T1DPs and 31 healthy subjects. Fasting C-peptide levels were measured in healthy subjects and T1DPs. The Mixed-meal tolerance test (MMTT) was performed in T1DPs. Fasting and stimulated (90 minute post MMTT) C-peptide levels were measured via electrochemiluminescence assay. Two categorizations were made according to fasting (the first categorization ) and at 90th minute MMTT (the second categorization) C-peptide levels. For the first categorization; the groups were classified as follows: patients with undetectable ≤0.1ng/mL(group1); minimal 0.1-0.8ng/mL(group2); and sustained ≥0.8ng/mL (group3) C-peptide levels. For the second categorization, groups were as follows: patients with undetectable ≤0.1 ng/mL(group1); minimal 0.1-0.8 ng/ml (group2); and sustained ≥0.8ng/mL (group3) in which C peptide levels were increased to ≥150% of fasting C-peptide levels at the 90th minute after MMTT. Results For the first category; 41.5%, 40% and 18.5% of T1DPs were in group1, group2 and group3, respectively. For the second category; 34.8%, 20.7% and 44.4% were in group1, group2 and group3, respectively. In first categorization 58.5% and in second categorization 65.1% of T1DPs had detectable C-peptide levels. 44,4%of the T1DPs had a response to MMTT with C-peptide levels ≥0.8 ng/mL which increased to ≥150% of fasting C-peptide level at the 90th minute after MMTT as it is seen in non-diabetics. Conclusion The present study suggests the presence of functioning β-cells in T1DPs and 44.4 % of T1DPs have a response to MMTT as seen in non-diabetics. (ClinicalTrials.gov number: NCT02199470.)