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18. Crystallization kinetics in Cu50Zr42.5Ti7.5 bulk metallic glass.

Author

Bykov, V. A., Kulikova, T. V., Kovalenko, D. A., Estemirova, S. Kh., and Ryltsev, R. E.

Subjects
*METALLIC glasses, *BINARY metallic systems, *TERNARY alloys, *CRYSTALLIZATION kinetics, *AUTOCATALYSIS, *COMPOSITE materials, *DIFFERENTIAL scanning calorimetry, *ACTIVATION energy
Abstract

The production of modern composite materials based on bulk metallic glasses requires knowledge of their primary crystallization processes during heating (BMG). Here, we investigate the structure and crystallization kinetics of a promising modern BMG/B2 nano-composites, a fast-hardened glass-forming alloy Cu50Zr42.5Ti7.5. The complex four-step crystallization of the glass alloy at different heating rates was revealed by differential scanning calorimetry. The process of a crystallization was successfully fully described by a multiverse nonlinear kinetic model, and the kinetic parameters were determined with high accuracy. The best way to describe the four-step crystallization of a glass alloy is the two-branch parallel reaction. The first branch is described by three consecutive n-order autocatalytic reactions. The second branch obeys the Avrami-Erofeev model. The high thermal stability of the amorphous state is evidenced by the average full process crystallization activation energy Ea = 425 kJ mol−1. Analysis of the obtained results and their comparison with available literature data allow us to conclude that the crystallization process in glassy Cu50Zr42.5Ti7.5 alloy (and probably other similar ternary alloys based on binary Cu50Zr50 system) is strongly affected by the structure of initial sample as well as by thermal conditions. The presence of nano-sized inclusion of metastable phases (for example, B2 one) can change the sequence of reaction as well as the structure of phases forming at each stage. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Thermally initiated disproportionation of manganese(II) bis(1-hydroxyethylidene)diphosphonate. Formation and properties of the lepidoid structure of manganese(II) (1-hydroxyethylidene)diphosphonate-2-hydroxyethaneaminium whiskers. Agronomical efficiency of the manganese(II) complex with (1-hydroxyethylidene)diphosphonic acid

Author

Semenov, V. V., Zolotareva, N. V., Petrov, B. I., Novikova, O. V., Kulikova, T. I., Razov, E. N., Kruglov, A. V., Kotomina, V. E., Geiger, E. Yu., Varlamova, L. D., Titova, V. I., Korchenkina, N. A., and Sakov, A. P.

Published
2018
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39. Recent Achievements in Electrochemical and Surface Plasmon Resonance Aptasensors for Mycotoxins Detection

Author

Evtugyn, G., Porfireva, A., Kulikova, T., and Hianik, T.

Subjects
APTASENSOR, SURFACE PLASMON RESONANCE, MYCOTOXIN ANALYSIS, APTAMER, ELECTROCHEMICAL SENSOR
Abstract

Mycotoxins are secondary metabolites of fungi that contaminate agriculture products. Their release in the environment can cause severe damage to human health. Aptasensors are compact analytical devices that are intended for the fast and reliable detection of various species able to specifically interact with aptamers attached to the transducer surface. In this review, assembly of electrochemical and surface plasmon resonance (SPR) aptasensors are considered with emphasis on the mechanism of signal generation. Moreover, the properties of mycotoxins and the aptamers selected for their recognition are briefly considered. The analytical performance of bio-sensors developed within last three years makes it possible to determine mycotoxin residues in water and agriculture/food products on the levels below their maximal admissible concentrations. Requirements for the development of sample treatment and future trends in aptasensors are also discussed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Funding: T.K. acknowledges funding by the subsidy allocated to Kazan Federal University for the state assignment in the sphere of scientific activities (grant No 0671–2020−0063). T.H. acknowledges funding from the Science Grant Agency VEGA, project No.: 1/0419/20.

Published
2021

40. Electrochemical Sensing of Interactions between DNA and Charged Macrocycles

Author

Kulikova, T., Padnya, P., Shiabiev, I., Rogov, A., Stoikov, I., Evtugyn, G., Kulikova, T., Padnya, P., Shiabiev, I., Rogov, A., Stoikov, I., and Evtugyn, G.

Abstract

In this work, we investigated aggregation of native DNA and thiacalix[4]arene derivative bearing eight terminal amino groups in cone configuration using various redox probes on the glassy carbon electrode. It was shown that sorption transfer of the aggregates on the surface of the electrode covered with carbon black resulted in changes in electrostatic interactions and diffusional permeability of the surface layer. Such changes alter the signals of ferricyanide ion, methylene green and hydroquinone as redox probes to a degree depending on their specific interactions with DNA and own charge. Inclusion of DNA in the surface layer was independently confirmed by scanning electron microscopy, electrochemical impedance spectroscopy and experiments with doxorubicin as a model intercalator. Thermal denaturing of DNA affected the charge separation on the electrode interface and the signals of redox probes. Using hydroquinone, less sensitive to electrostatic interactions, made it possible to determine from 10 pM to 1.0 nM doxorubicin (limit of detection 3 pM) after 10 min incubation. Stabilizers present in the commercial medications did not alter the signal. The DNA sensors developed can find future application in the assessment of the complexes formed by DNA and macrocycles as delivery agents for small chemical species. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Published
2021

41. Electrochemical DNA Sensor Based on Acridine Yellow Adsorbed on Glassy Carbon Electrode

Author

Kulikova, T., Porfireva, A., Rogov, A., Evtugyn, G., Kulikova, T., Porfireva, A., Rogov, A., and Evtugyn, G.

Abstract

Electrochemical DNA sensors offer unique opportunities for the sensitive detection of specific DNA interactions. In this work, a voltametric DNA sensor is proposed on the base of glassy carbon electrode modified with carbon black, adsorbed acridine yellow and DNA for highly sensitive determination of doxorubicin antitumor drug. The signal recorded by cyclic voltammetry was attributed to irreversible oxidation of the dye. Its value was altered by aggregation of the hydrophobic dye molecules on the carbon black particles. DNA molecules promote disaggregation of the dye and increased the signal. This effect was partially suppressed by doxorubicin compensate for the charge of DNA in the intercalation. Sensitivity of the signal toward DNA and doxorubicin was additionally increased by treatment of the layer with dimethylformamide. In optimal conditions, the linear range of doxorubicin concentrations determined was 0.1 pM–1.0 nM, and the detection limit was 0.07 pM. No influence of sulfonamide medicines and plasma electrolytes on the doxorubicin determination was shown. The DNA sensor was tested on two medications (doxorubicin-TEVA and doxorubicin-LANS) and showed recoveries of 102–105%. The DNA sensor developed can find applications in the determination of drug residues in blood and for the pharmacokinetics studies. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Published
2021

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