A brief review of studies of crystals containing metal ions with unfilled
f
- or
d
-shells, made in the Institute of Spectroscopy of the Russian Academy of Sciences by high-resolution Fourier ...spectroscopy, is given. The main directions of study include hyperfine structure in spectra, isotopic effects, the role of random deformations, phase transition spectroscopy, low-dimensional magnets, coupled electron–phonon excitations.
We synthesised a new type of photochromic tungsten oxide nanoparticles, analysed their photocatalytic activity and carried out a thorough analysis of their effect on prokaryotic and eukaryotic ...organisms. Ultrasmall hydrated tungsten oxide nanoparticles were prepared by means of hydrothermal treatment of tungstic acid in the presence of polyvinylpyrrolidone as a template, stabiliser and growth regulator. Tungstic acid was synthesised through an ion-exchange method using sodium tungstate solution and a strongly acidic cation exchange resin.
Upon illumination, photochromic nanoparticles of WO3 were shown to increase greatly their toxicity against both bacterial (both gram-positive and gram-negative – P. aeruginosa, E. coli and S. aureus) and mammalian cells (primary mouse embryonic fibroblasts); under the same conditions, fungi (C. albicans) were less sensitive to the action of tungsten oxide nanoparticles. UV irradiation of primary mouse fibroblasts in the presence of WO3 nanoparticles demonstrated a time- and dose-dependent toxic effect, the latter leading to a significant decrease in dehydrogenase activity and an increase in the number of dead cells. WO3 nanoparticles were photocatalytically active under both UV light and even diffused daylight filtered through a window glass, leading to indigo carmine organic dye discolouration.
The obtained experimental data not only show good prospects for biomedical applications of tungsten trioxide, but also demonstrate the need for clear control of biosafety when it is used in various household materials and appliances.
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•Photochromic WO3 nanoparticles were synthesised using ion-exchange method.•UV increased toxicity of WO3 nanoparticles against bacterial and mammalian cells.•WO3 nanoparticles were photocatalytically active under UV-illumination.
Abstract
The studies were carried out on the experimental field of Krasnoyarsk Research Institute of Agriculture in Krasnoyarsk open forest-steppe in 2012-2014. The agrometeorological conditions of ...the crop season during the years of research developed in contrast: from arid in 2012 (GTC - 0.84) to excessively wet in 2013 (GTC - 2.20), which led to significant variation in yield. The study of samples of naked and aristulate spelt wheat in comparison with the standard variety of durum spring wheat Omskaya Stepnaya (Omsk region) in terms of ecological plasticity and stability made it possible to isolate valuable samples for further selection. In terms of yield among naked spelt wheat, samples from Leningrad region are of greatest interest: L 133*Protein is 246.33 g/m
2
, L 196/3 L-13 is 271.16 g/m
2
, L 133*Pkk is 249.17 g/m
2
. From filmy emmer wheat, the varieties Belka (Leningrad Region) (472.00 g/m
2
) and Runo (Krasnodar Territory) (407.25 g/m
2
) exceeded the standard for this indicator. In breeding varieties of spelt wheat a sample of naked spelt wheat - L 71/10 (Leningrad region) can be used as a source as it is the most responsive variety to improving growing conditions (intensive background); and when creating varieties with stable yields, durum spring wheat Omskaya stepnaya (Omsk region) can be used as a source.
Phonon anomaly in Sm2BaNiO5 Klimin, S A; Popova, E A; Popova, M N
Journal of physics. Conference series,
11/2019, Letnik:
1389, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
We present low-temperature far-infrared study of Sm2BaNiO5. The lowest-frequency phonon of Sm2BaNiO5 generated by the motion of the Sm3+ ion demonstrates anomalous behaviour at temperatures lower ...than the Néel temperature, T<TN=55 K. This phonon hardens at the magnetic ordering although its frequency shift does not follow the magnetic order parameter. The observed phenomenon is responsible for an unusual dielectric response of Sm2BaNiO5 reported in the literature. A correlation between the temperature behaviour of crystal-field levels and the phonon anomaly is discussed.
The level P-glycoprotein (Pgp) in organs of pregnant rabbits and its content and activity in the placental barrier at different stages of pregnancy were studied. An increase in Pgp content in the ...jejunum on days 7, 14, 21, and 28 of pregnancy in comparison with this parameter non-pregnant females was revealed by ELISA; in the liver, Pgp content was higher on day 7 and tended to increase on day 14; in the kidney and cerebral cortex, Pgp content was higher on day 28 of pregnancy in parallel with an increase in serum progesterone concentration. We also observed a decrease in Pgp content in the placenta on days 21 and 28 of pregnancy in comparison with day 14 and a decrease in Pgp activity in the placental barrier, which was confirmed by enhanced penetration of fexofenadine (Pgp substrate) through the barrier.
•No long-range magnetic order was found in Pr3CrGe3Be2O14 langasite down to 0.4 K.•Isolated 1D chains of S = 3/2 Cr3+ are situated perpendicular to 2D Kagomé -layers of Pr3+.•Crystal-field splitting ...of Pr3+ levels explains Schottky anomaly in specific heat.
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We present the results of thermodynamic and optical spectroscopy measurements of the Pr3CrGe3Be2O14 compound - a member of the recently discovered Be-subgroup of the langasite family. Despite the presence of both rare-earth and transition-metal subsystems in Pr3CrGe3Be2O14, no long-range magnetic order has been found down to 0.4 K in terms of both magnetization M and specific heat Cp. These data are compared with those on Pr3AlGe3Be2O14. Both compounds evidence the Schottky anomaly at low temperatures, most pronounced in the case of Pr3CrGe3Be2O14.
Tunka-133: Results of 3 year operation Prosin, V.V.; Berezhnev, S.F.; Budnev, N.M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2014, Letnik:
756
Journal Article
Recenzirano
Odprti dostop
The EAS Cherenkov light array Tunka-133, with ~3km2 geometric area, is taking data since 2009. The array permits a detailed study of cosmic ray energy spectrum and mass composition in the PeV energy ...range. After a short description of the methods of EAS parameter reconstruction, we present the all-particle energy spectrum and results of studying CR composition, based on 3 seasons of array operation. In the last part of the paper, we discuss possible interpretations of the obtained results.
The family of RFe
3(BO
3)
4 borates (R=Pr, Nd, Eu–Er, Y) was studied by high-resolution optical absorption and Raman spectroscopies. Structural and magnetic phase transitions were detected and the ...types of magnetic structure were determined. Energy of crystal-field (CF) levels and exchange splitting of the ground state of the R
3+ ion were obtained from the analysis of optical spectra. CF calculations were carried out. Effective magnetic field at the R
3+ site was found, using the calculated value of the magnetic
g-factor. Some peculiarities of modeling the paramagnetic susceptibility of NdFe
3(BO
3)
4 are discussed.
The high-resolution optical absorption spectra of NdFe
3
(BO
3
)
4
single crystals have been recorded at temperatures from 4 to 40 K in the IR range of
f
–
f
transitions in a Nd
3+
ion. Light ...linearly polarized at different angles to the
C
2
axes in the basal plane has been passed along the trigonal
C
3
axis. Below the temperature of magnetic moment ordering into a collinear antiferromagnetic structure (
T
N
≈ 30 K), dichroism, that is, the absorption versus polarization dependence, arises. The temperature and angular dependences of dichroism indicate that the magnetic moments of iron are directed along the
C
2
axes up to about 17 K, the number of domains with variously directed
C
2
axes being different. The mechanism of linear dichroism has been discussed. Below 17 K, a smooth transition to the helicoidal magnetic phase has been observed, with the collinear phase coexisting with the helicoidal one. Data presented in this article contradict the earlier concept of magnetic moments fluctuating in the low-temperature phase near the
C
2
axis within the ±10° interval.
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