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338 results on '"Andreeva, D."'

5. Piezoelectricity in monolayer hexagonal boron nitride

Author

Ares, P., Cea, T., Holwill, M., Wang, Y. B., Roldan, R., Guinea, F., Andreeva, D. V., Fumagalli, L., Novoselov, K. S., and Woods, C. R.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

Two-dimensional (2D) hexagonal boron nitride (hBN) is a wide-bandgap van der Waals crystal with a unique combination of properties, including exceptional strength, large oxidation resistance at high temperatures and optical functionalities. Furthermore, in recent years hBN crystals have become the material of choice for encapsulating other 2D crystals in a variety of technological applications, from optoelectronic and tunnelling devices to composites. Monolayer hBN, which has no center of symmetry, has been predicted to exhibit piezoelectric properties, yet experimental evidence is lacking. Here, by using electrostatic force microscopy, we observed this effect as a strain-induced change in the local electric field around bubbles and creases, in agreement with theoretical calculations. No piezoelectricity was found in bilayer and bulk hBN, where the centre of symmetry is restored. These results add piezoelectricity to the known properties of monolayer hBN, which makes it a desirable candidate for novel electromechanical and stretchable optoelectronic devices, and pave a way to control the local electric field and carrier concentration in van der Waals heterostructures via strain. The experimental approach used here also shows a way to investigate the piezoelectric properties of other materials on the nanoscale by using electrostatic scanning probe techniques.

Published
2019
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9. Interfacial Cracks in Piezoelectric Bimaterials: an approach based on Weight Functions and Boundary Integral Equations

Author

Pryce, L., Morini, L., Andreeva, D., and Zagnetko, A.

Subjects
Mathematical Physics
Abstract

The focus of this paper is on the analysis of a semi-infinite crack lying along a perfect interface in a piezoelectric bimaterial with arbitrary loading on the crack faces. Making use of the extended Stroh formalism for piezoelectric materials combined with Riemann-Hilbert formulation, general expressions are obtained for both symmetric and skew-symmetric weight functions associate with plane crack problems at the interface between dissimilar anisotropic piezoelectric media. The effect of the coupled electrical fields is incorporated in the derived original expressions for the weight function matrices. These matrices are used together with Betti's reciprocity identity in order to obtain singular integral equations relating the extended displacement and traction fields to the loading acting on the crack faces. In order to study the variation of the piezoelectric effect, two different poling directions are considered. Examples are shown for both poling directions with a number of mechanical and electrical loadings applied to the crack faces., Comment: 27 pages, 3 figures

Published
2015

19. Layered material platform for surface plasmon resonance biosensing

Author

Wu, F., Thomas, P. A., Kravets, V. G., Arola, H. O., Soikkeli, M., Iljin, K., Kim, G., Kim, M., Shin, H. S., Andreeva, D. V., Neumann, C., Küllmer, M., Turchanin, A., De Fazio, D., Balci, O., Babenko, V., Luo, B., Goykhman, I., Hofmann, S., Ferrari, A. C., Novoselov, K. S., and Grigorenko, A. N.

Published
2019
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23. PREGNANCY-ASSOCIATED HEPATOPATHY.

Author

Tsonev, N., Notev, D., Gashkova, D., Kostov, I., Ivanova, E., Zvezdov, D., Andreeva, D., Toncheva, K., Vandeva, D., and Stefanova, M.

Published
2023

26. Features of Organic Matter Transformation in the Active Layer of Permafrost in the Bureya River Basin.

Author

Kondratyeva, L. M., Andreeva, D. V., Litvinenko, Z. N., Shesterkin, V. P., and Golubeva, E. M.

Subjects
WATERSHEDS, PERMAFROST, SOIL freezing, METEOROLOGICAL precipitation, HUMUS, COMPOSITION of water
Abstract

Climate change results in increased attention to factors determining the dynamics of biogeochemical processes in the active layer of biosphere (seasonally thawing/freezing soils) at the boundary with permafrost. There are geological, geomorphic, and weather conditions associated with atmospheric precipitation, which determine the differences in the segregation and the thawing depth of permafrost in various regions. The research area is the Bureya River Basin with discontinuous permafrost within unique landscape units: Mari. They are formed in swampy and poorly drained areas where the active soil layer is in contact with permafrost, and they exert a direct impact on the quality of surface waters. The results of the study include data on the chemical composition of water in tributaries of different orders; spectral characteristics of soluble organic matter (OM) in water extracts (WEs) of soils from different horizons of the active layer; and the assessment of the activity of microbial complexes in relation to humic substances (HSs), depending on the permafrost depth. The heterogeneity of landscapes is an important factor, influencing the transport of OM into watercourses. Microbial complexes of the active layer involved in the transformation of HSs play a decisive role in changing the composition of soluble OM. It is experimentally shown that temperature affects the qualitative composition of metabolism products of HSs, including the ratio of aliphatic and aromatic fragments to chromophoric groups responsible for the color of natural waters. [ABSTRACT FROM AUTHOR]

Published
2023
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50. Drug-Induced Anaphylactic Shock

Author

Matveev, A. V., primary, Krasheninnikov, A. E., additional, Belostotsky, A. V., additional, Andreeva, D. M., additional, Marchenko, S. D., additional, and Egorova, E. A., additional

Published
2020
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