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Photochromic aerogels based on cellulose and chitosan modified with WO3 nanoparticles
Nanosystems: Physics, Chemistry, Mathematics. 2022. Vol. 13. No. 4. P. 404–413.
Kameneva S.V., Popkov M. A., Tronev I.V., Kottsov S. Y., Sozarukova M. M., Ivanov V.
In this work, we report the first synthesis of photochromic aerogels and films based on TEMPO-oxidized cellulose and chitosan modified with tungsten trioxide nanoparticles. The blue coloring of aerogels based on WO3-modified biopolymers under UV light occurs due to the reduction of WO+6 to WO+5. The coloration of films of the same composition occurs due to the reduction of W+6 to W+5 and W+4. The photochromic properties of aerogels and films are reversible; oxidation by atmospheric oxygen leads to bleaching of materials. At that, films become colorless within a few days while aerogels with a high specific surface area (200 m2/g) become colorless within several minutes. The antioxidant properties of the WO3 sol and the WO3/TEMPO-oxidized cellulose/chitosan composite were studied by luminol-activated chemiluminescence method. The antioxidant capacity of WO3/TEMPO-oxidized cellulose/chitosan gel is 1.5 times higher than that of the commercially available antioxidant mexidol.
Keywords: aerogel
Дмитриев В. В., Петрова Д. В., Солдатов А. А. et al., Успехи физических наук 2024 Т. 194 № 12 С. 1310–1319
The article presents the results of experiments in superfluid 3He, performed using a vibrating wire resonator with a nematic aerogel glued to it, which allowed detecting transitions of He to new superfluid phases: to the polar phase, β-phase, and the distorted A- and β-phases. Experiments on observing the A1-phase in a nematic aerogel are also ...
Added: November 8, 2024
Dmitriev V. V., Kutuzov M. S., Soldatov A. A. et al., Physical Review B: Condensed Matter and Materials Physics 2023 Vol. 107 No. 2 Article 024507
We present the results of high magnetic field experiments in pure 3He (in the absence of 4He coverage) in nematic aerogel. In this case the aerogel strands are covered with few atomic layers of solid paramagnetic 3He, which enables the spin-exchange mechanism for 3He quasiparticles scattering. Our earlier NMR experiments showed that in low fields, ...
Added: January 16, 2024
Zhukov A., Гурьев В. В., Жолудов В. С. et al., М.: МИСИ – МГСУ, 2021.
The monograph summarizes and systematizes the results of experimental and theoretical studies of thermal insulation in industrial structures, technological facilities, pipelines and building structures. Modern types of thermal insulation materials based on heat-resistant gas-filled plastics, foamed glass, foamed rubber, aerogels and products made of mineral fibers are considered.
The basic ideas about the morphology of gas—filled ...
Added: January 31, 2023
Dmitriev V. V., Kutuzov M. S., Soldatov А. А. et al., JETP Letters 2020 Vol. 112 No. 12 P. 780–785
We present experiments on nematic aerogel oscillating in superfluid 3He. This aerogel consists of nearly parallel mullite strands and is attached to a vibrating wire moving along the direction of the strands. Previous nuclear magnetic resonance experiments in 3He confined in similar aerogel sample have shown that the superfluid transition of 3He in aerogel occurs into the polar ...
Added: October 29, 2022
Dmitriev V. V., Kutuzov M. S., Soldatov A. A. et al., Physical Review Letters 2021 Vol. 127 No. 26 Article 265301
It is known that in low magnetic fields the superfluid transition of 3He in nematic aerogel occurs into the polar phase. Using a vibrating aerogel resonator, we observe that in high magnetic fields this transition splits into two discrete transitions, occurring at different temperatures. According to theoretical models, a new superfluid phase— the β phase— should be realized between ...
Added: October 17, 2022
Yorov K., Zhdanov A., Kamilov R. et al., ACS Applied Nano Materials 2022 Vol. 5 No. 8 P. 11529–11538
An alkoxysilane derivative bearing 10-vertex closo-decaborate nanocluster (B10H102–) was successfully synthesized and immobilized in SiO2 aerogel matrix. closo-Decaborate-containing SiO2 aerogels showed high specific surface (~750 m2/g), open porosity (~95 %) and extremely low apparent density (80 mg/cm3) as well as increased thermal stability of closo-decaborate moiety. Despite the low boron content (~1.2 mol.% of boron ...
Added: October 13, 2022
Ivanov V., ACS Omega 2020 Vol. 5 No. 28 P. 17592–17600
Added: October 4, 2021
Dmitriev V. V., Kutuzov M. S., Soldatov A. A. et al., JETP Letters 2020 Vol. 112 No. 12 P. 780–785
We present experiments on nematic aerogel oscillating in superfluid 3He. This aerogel consists of nearly parallel mullite strands and is attached to a vibrating wire moving along the direction of the strands. Previous nuclear magnetic resonance experiments in 3He confined in similar aerogel sample have shown that the superfluid transition of 3He in aerogel occurs into the polar ...
Added: February 2, 2021
Dmitriev V. V., Kutuzov M. S., Melnikovsky L. A. et al., JETP Letters 2020 Vol. 112 P. 262
Erratum to the article ...
Added: December 4, 2020
Dmitriev V. V., Kutuzov M. S., Mikheev A. Y. et al., Physical Review B: Condensed Matter and Materials Physics 2020 Vol. 102 P. 144507
We report results of experiments with liquid 3He confined in a high-porosity anisotropic nanostructure which we call planar aerogel. This aerogel consists of nanofibers (with diameters ∼10 nm) which are randomly oriented in the plane normal to the specific axis. We used two samples of planar aerogel prepared using different techniques. We have found that on cooling from the ...
Added: December 4, 2020
Дмитриев В. В., Солдатов А. А., Юдин А. Н., Журнал экспериментальной и теоретической физики 2020 Т. 158 № 1 С. 6–16
In nematic aerogels, their constituent fibers are oriented along the same direction. In liquid 3He filling such aerogels, the scattering of Fermi quasiparticles at ultralow temperatures becomes anisotropic. This makes it possible to obtain new superfluid phases of 3He, which are not observed in bulk 3He. In this article, results of NMR investigation of these new superfluid phases ...
Added: December 4, 2020
Yorov K. E., Kottsov S. Y., Baranchikov A. E. et al., Journal of Sol-Gel Science and Technology 2019 Vol. 92 No. 2 P. 304–318
A procedure for the chemical immobilization of a new ZnII–EuIII heterobimetallic complex in the SiO2 aerogel matrix has been developed. In this Zn–Eu complex, a peripheral non-luminescent Zn ion acts as a binder to a silica matrix and prevents direct interaction of rare-earth ions with OH− and NH− groups in the silica matrix, which would have a ...
Added: May 27, 2020
Dmitriev V. V., Kutuzov M. S., Soldatov A. A. et al., JETP Letters 2019 Vol. 110 No. 11 P. 748–749
We present results of nuclear magnetic resonance (NMR) experiments in superfluid 3He in two samples of nematic aerogel consisting of nearly parallel mullite strands. The samples were cut from the same piece of the aerogel, but one of them was squeezed by 30% in the direction transverse to the strands. In both samples the superfluid ...
Added: November 21, 2019
Dmitriev V. V., Kutuzov M. S., Soldatov A. A. et al., JETP Letters 2018 Vol. 108 No. 12 P. 827–828
Magnetic materials generate demagnetizing field that depends on geometry of the sample and results in a shift of magnetic resonance frequency. This phenomenon should occur in porous nanostructures as well, e.g., in globally anisotropic aerogels. Here we report results of nuclear magnetic resonance (NMR) experiments with liquid 3He confined in anisotropic aerogels with different types of ...
Added: November 23, 2018
Dmitriev V. V., Kutuzov M. S., Melnikovsky L. A. et al., JETP Letters 2018 Vol. 108 No. 11 P. 772–773
We report the results of theoretical and experimental investigation of spin diffusion in the normal phase of liquid 3He confined in planar aerogel: a material consisting of nanostrands which are almost parallel to a specific plane and randomly oriented in this plane. Using spin echo technique we measure the spin diffusion coefficients in the directions perpendicular ...
Added: November 23, 2018
Autti S., Dmitriev V. V., Mäkinen J. T. et al., Physical Review Letters 2018 Vol. 121 No. 2 P. 025303-1–025303-6
The polar phase of 3He, which is topological spin-triplet superfluid with the Dirac nodal line in the spectrum of Bogoliubov quasiparticles, has been recently stabilized in a nanoconfined geometry. We pump magnetic excitations (magnons) into the sample of polar phase and observe how they form a Bose-Einstein condensate, revealed by coherent precession of the magnetization of ...
Added: November 23, 2018
Dmitriev V. V., Soldatov A. A., Yudin A. N., Physical Review Letters 2018 Vol. 120 No. 7 P. 075301-1–075301-5
We report results of experiments with superfluid 3He confined in aerogels with parallel strands which lead to anisotropic scattering of 3He quasiparticles. We vary boundary conditions for the scattering by covering the strands with different numbers of atomic 4He layers and observe that the superfluid phase diagram and the nature of superfluid phases strongly depend on the coverage. We assume the ...
Added: February 21, 2018
Volkov V. V., Dmitriev V. V., Zolotukhin D. V. et al., Instruments and Experimental Techniques 2017 Vol. 60 No. 5 P. 737–741
A method is described that allows the synthesis of denser samples of a nematically ordered aerogel from commercial Nafen with the effective density of 72 mg/cm3. The method is based on the drying of Nafen pre-immersed in a liquid (water, ethanol, pentane, or liquid nitrogen). The density of the final product is measured as a ...
Added: December 26, 2017
Асадчиков В. Е., Асхадуллин Р. Ш., Волков В. В. et al., Письма в Журнал экспериментальной и теоретической физики 2015 Т. 101 С. 613–619
The microstructure, specific area, and mechanical properties of various samples of “nematically ordered” aerogels whose strands are almost parallel to each other at macroscopic distances have been studied. The strong anisotropy of such aerogels distinguishes them from standard aerogels, which are synthesized by solgel technology, and opens new possibilities for physical experiments. ...
Added: December 26, 2017