It has been shown that treatment with titanium dioxide nanoparticles (TiO2 NPs) combined with near-ultraviolet (UV-A) irradiation or in certain dark conditions reduced the numbers of various ...microorganisms, but the mechanism of this effect remains unclear. In this study to further clarify the mechanism of the antibacterial effect of TiO2 NPs the physiological state of E. coli K12 cells was estimated after incubation with the NPs (0.2 g/L) for different periods of time, with or without UV-A irradiation. Cell incubation with TiO2 NPs, combined or not combined with UV-A irradiation, showed that inactive cells were located only within cell aggregates formed after incubation with TiO2 NPs and that the larger the aggregate, the greater the number of such cells. When the formation of large aggregates was prevented, exposure to NPs under UV-A irradiation failed to result in cell inactivation. A comparative analysis of fluorescence and optical microscopic images of the same aggregates showed that the location of inactivated cells coincided with the zone of increased optical density within the aggregate. After treatment with TiO2 NPs under UV-A for 30, 60, or 120 min cells within the aggregates were the first to be inactivated. Cells on which NPs irradiated more strongly (at the periphery of large aggregates and single) remained active for a longer time than cells within the aggregates. As the time of treatment increased, so did the degree of cell compaction, with some zones of the aggregates eventually transforming into an acellular mass. After UV-A irradiation the cell aggregates spontaneously moved toward each other and gradually fused into larger structures, indicating that such exposure enhanced mutual attraction of cells treated with the NPs. Present study provides evidence for hypothesis that bacterial cells covered with TiO2 NPs are inactivated due to their mutual attraction and consequent compression.
We studied the effect of heating on the magnetic properties and giant magnetoimpedance (GMI), effect of Co69.2Fe3.6Ni1B12.5Si11Mo1.5C1.2 glass-coated microwires with vanishing magnetostriction. We ...observed, that upon heating the hysteresis loop changed its shape from inclined to rectangular. These changes in hysteresis loop shape correlate with modification of magnetic field dependencies of GMI ratio, ΔZ/Z, from double-peak to single-peak and with change in value of maximum GMI ratio. The origin of the observed changes in the hysteresis loop and the GMI effect is discussed in terms of the Hopkinson effect, internal stresses relaxation upon heating, and the temperature dependencies of internal stresses and the magnetostriction coefficient.
Influence of Joule heating on magnetic properties and GMI effect of Fe75B9Si12C4 glass-coated microwires was studied. A decrease in coercivity after Joule heating is observed, while hysteresis loops ...of Joule heated samples maintain a rectangular shape. However, a remarkable increase in GMI ratio is observed in Joule heated samples. Observed GMI ratio improvement has been discussed considering magnetic anisotropy induced by Oersted magnetic field during Joule heating and internal stress relaxation. A remarkable GMI effect improvement observed in Joule heated Fe-rich microwires, along the fact that Fe is a more common, less expensive metal than Co, makes them suitable for magnetic sensor applications.
We studied the temperature dependence of the magnetic properties and giant magnetoimpedance, GMI, effect in as-prepared and annealed Co69.2Fe3.6Ni1B12.5Si11Mo1.5C1.2 glass-coated microwires with ...nearly-zero magnetostriction. Substantial changes in the GMI ratio, ΔZ/Z, value and magnetic field, H, dependence, and in the hysteresis loops upon heating were observed. The modification in the hysteresis loop shape upon heating correlates with a change in the ΔZ/Z (H) dependencies. In as-prepared and most of the heat treated samples the hysteresis loop transformation from inclined to squared upon heating correlates with the change in ΔZ/Z(H) dependencies from double-peak to single-peak. However, the stress-annealed at 118 MPa samples present better thermal stability of the ΔZ/Z(H) dependencies and hysteresis loops. In all the studied samples an increase in the GMI ratio at 300 °C was observed. The origin of the observed temperature dependences is discussed in terms of the Hopkinson effect, temperature dependence and relaxation of internal stresses, induced magnetic anisotropy, and temperature dependence of the magnetostriction coefficient.
•Substantial temperature dependence of hysteresis loops of Co-rich glass-coated microwire.•Significant temperature dependence of GMI effect of Co-rich glass-coated microwires.•Almost complete reversibility of the hysteresis loops in properly annealed Co-rich glass-coated microwires after heating.•Enhanced thermal stability of the GMI in properly stress-annealed Co-rich glass-coated microwires.•Temperature dependence of the GMI effect in Co-rich microwires suitable for temperature monitoring.
We observed that magnetic properties (Giant magneto.-impedance effect and domain wall dynamic) of glass-coated microwires are closely related with the peculiarities of the fabrication technique ...involving rapid solidification of metallic alloy surrounded by glass coating from the melt.
We present studies of the interfacial layer between the metallic nucleus and glass coating and studies of the inhomogeneities related with fabrication process of thin ferromagnetic microwires.
We observed gas bubbles within the glass coating with volume content of about 8–12%. The sizes of the bubbles were between 1 and 15 μm. The existence of such bubbles might be the origin of the inhomogeneities in the internal stresses distribution.
Using scanning electron microscope JEOL JSM-6610 we obtained the image of the interfacial layer and the elements distribution within the glass coating and metallic nucleus. This allowed us to estimate the thickness of the interfacial layer.
Understanding of the origins of the interfacial layer and defects may help for improvement of the existing technology for thin composite wires fabrication and enhance their magnetic properties.
•Observation of interfacial layer between the glass coating and metallic nucleus.•Evaluation of the elements distribution within the glass coating and metallic nucleus.•Discussions of the effect of interfacial layer on magnetic properties of microwires.•Observation of gas bubbles within the glass coating with volume content of about 8–10%.•Discussions of the effect of gas bubbles on the inhomogeneities in the internal stresses distribution.
To determine the statistical significance of the north–south (N–S) asymmetry of active regions (ARs) of different magneto-morphological classes (MMCs), 3553 ARs that appeared on the solar disk from ...June 1996 to December 2020 according to the MMC ARs CrAO catalog (
http://sun.crao.ru/databases/catalog-mmc-ars
) were studied. All ARs, except for unipolar sunspots, were distributed between two classes: the regular bipolar groups (following the Hale’s polarity law, Joy’s law, the leading spot dominance rule) and the irregular ARs (all the rest). The statistical significance of the N–S asymmetry was determined for each class of ARs for each of the two maxima of the 23rd and 24th solar cycles in several ways based on the use of a normal approximation of the binomial distribution and Pearson’s goodness-of-fit
-test. The obtained simplified expressions can be used for some other astrophysical problems where objects are distributed between two classes. A high level of statistical significance of the observed N–S asymmetry (the probability of the observed deviations randomness is less than the significance level α = 0.01, i.e., 1%) was found for the regular ARs in both maxima of the 24th cycle and for the irregular ARs in the second maximum of each of the studied cycles. The temporal profiles of all AR subsets demonstrate the signs of the double-peak structure of the cycle; the peaks of ARs from different subsets occur sometimes in-phase and sometimes out-of-phase. The most pronounced manifestations of N–S asymmetry are observed for the irregular ARs in the second maximum of the cycle. In this time interval, characterized by the weakening of the global dynamo, the conditions for the manifestation of the turbulent component of the dynamo and distortion of the ARs magnetic tubes are created. The predominance of the irregular ARs in the S-hemisphere may be explained by an additional weakening of the toroidal field due to the interaction of the dipole and quadrupole components of the magnetic field.
Nudibranchs are mostly predators preying on a variety of invertebrates. The dietary preferences of tropical nudibranchs were studied by the method of fatty acid trophic markers (FATM) in order to for ...better understanding of their trophic ecology. For this, the fatty acid profiles of two nudibranch species from the South China Sea, Doriprismatica atromarginata (Cuvier, 1804) and Jorunna funebris (Kelaart, 1859), were analyzed and trophic markers were identified. The high level of very long chain fatty acids (from C24 to C28), which are characteristic of sponges, in nudibranchs was evidence of their predation on sponges. However, the distribution of these components differed significantly between the species. The acids 24:2Δ5,9, 25:2Δ5,9, 26:2Δ9,19, and especially 26:2Δ5,9 dominated in D. atromarginata, but were not found in J. funebris that was rich in 28:2Δ5,9 and 28:3Δ5,9,19. The significant differences in the profile of these demospongic acids indicate that these nudibranchs consumed different species of sponges. The similarity between the FATMs of J. funebris and its potential prey, the sponge Xestospongia, confirmed their predator–prey relationship. Doriprismatica atromarginata from different sites along the Vietnam coast had different FATM profiles, which showed this nudibranch as having no any strict food specialization and feeding on various Demospongiae species. The abundance of bacterial FATMs in the nudibranchs suggests the importance of bacteria in their diet. Thus, the FATM method has proven to be useful for identifying the feeding specialization and assessing the effect of food availability on the diet of these tropical nudibranch species.
The study shows that whole‐exome sequencing is a promising approach to detect novel variants—and gene candidates in DSD, that, as a future direction, may improve the diagnostic gene panels for this ...heterogeneous disorder.
The study shows that whole‐exome sequencing is a promising approach to detect novel variants—and gene candidates in DSD, that, as a future direction, may improve the diagnostic gene panels for this heterogeneous disorder
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