•Glass intensely luminesces in the region of 430; 612 nm.•Glass optically transparent in the visible range.•Glass is not stable when irradiated with an electron beam.•Sodium diffuses out of the ...electron beam irradiated area.
The purpose of this work is development of glasses for radioactive materials encapsulation. Borosilicate-based glass systems “R7/T7” (B2O3-ЅіO2-Al2O3-Na2O-СaO) doped with Eu3+, with various concentrations of activator were studied. The composition of the obtained glasses was investigated using electron-probe microanalysis technique. Optical properties of glasses were investigated using the following methods – cathodoluminescence, photoluminescence and absorption spectra. The range of the optimal activator concentration was determined. Samples of borosilicate glass (B2O3-ЅіO2-Al2O3-Na2O-СaO) doped with varied content of Eu3+ were synthesized and studied using electron probe microanalysis (EPMA) and optical techniques such as cathodoluminescence (CL), photoluminescence (PL) and light absorption spectroscopy. Glass composition was related to development of nuclear waste form or encapsulation matrix with sufficient resistance to radiation damage. It was observed that electron beam irradiation suppresses intensity of glass cathodoluminescence and this process is correlated with sodium diffusion outside irradiated area at comparable interval of time.
In this paper, we present the resistance measurements of the amorphous ferromagnetic Co-rich microwires (metallic nucleus diameters 15–30 μm) during Joule heating by direct current. The heating ...currents were provided by a programming power supply, which allowed setting up a different heating and cooling regimes. The Wheatstone bridge circuit was used for continuous resistance monitoring during the heating process. We observed the dependences of the microwire resistance versus the time and the applied power of heating for the samples having common composition Co69Fe4Cr4Si12B11 and different diameters. It was shown that the irreversible changes of the microwire resistance were occurred during heat treatment. The microwires have gone through a crystallization phase under linear varying power in the range between 0 and 4.5 W and their relative resistance reduced by up to 10% relative to the initial values. The one-time annealing run increases the relative resistance of the microwires samples from 0.1% to 1% at the various values of maximum power. The repeated heating processes result to the reversibility of the resistance values; in that case each value of maximum applied power provides finite rise of the microwire resistance value.
•Joule heating set-up for in-situ resistance measurements of amorphous ferromagnetic microwires has been developed.•Small electrical resistance changes during heating process has been monitored in Co69Fe4Cr4Si12B11 amorphous microwires.•The microwire resistance changes indicate the structural transformations occurring in the material.
This work presents, for the first time, data on the possibility of synthesizing polyimide nanocomposite films based on track nuclear membranes and organosiloxane (polyhedral oligomeric ...silsesquioxanes) POSS structures. The synthesis of the nanocomposite films was carried out by filling the tracks of a polyimide membrane with POSS structures under hydrothermal conditions in a high-pressure reactor. The surface and mechanical characteristics of the developed nanocomposite films were studied, and the results of their resistance to the flow of oxygen plasma are presented. It was found that the introduction of POSS structures significantly increased the resistance of polyimide to the flow of oxygen plasma. The PI/POSS composite exhibited an insignificant change in weight, the weight loss reached 0.92 ± 0.05 mg/cm2 in 24 h after the start of the experiment, which is almost two orders of magnitude lower than that of the polyimide film.
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•PI/POSS nanocomposite films obtained in a high-pressure reactor.•POSS structures are located in the tracks of the PI nuclear membrane.•The effect of oxygen plasma on PI and PI/POSS was investigated.•The erosion yield of PI – 3.05 × 10−24 cm3/atom, PI/POSS – 0.15 × 10−24 cm3/atom3.•Mechanical performance of PI/POSS nanocomposite films after oxygen plasma increased.
Prognosis of neuropsychiatric disorders in progeny requires consideration of individual (1) parent-of-origin effects (POEs) relying on (2) the nerve cell nuclear 3D chromatin architecture and (3) ...impact of parent-specific miRNAs. Additionally, the shaping of cognitive phenotypes in parents depends on both learning acquisition and forgetting, or memory erasure. These processes are independent and controlled by different signal cascades: the first is cAMPdependent, the second relies on actin remodeling by small GTPase Rac1 – LIMK1 (LIM-kinase 1). Simple experimental model systems such as Drosophila help probe the causes and consequences leading to human neurocognitive pathologies. Recently, we have developed a Drosophila model for Williams–Beuren Syndrome (WBS): a mutant
agn
ts3
of the
agnostic
locus (X:11AB) harboring the
dlimk1
gene. The
agn
ts3
mutation drastically increases the frequency of ectopic contacts (FEC) in specific regions of intercalary heterochromatin, suppresses learning/memory and affects locomotion. As is shown in this study, the polytene X chromosome bands in reciprocal hybrids between
agn
ts3
and the wild type strain
Berlin
are heterogeneous in modes of FEC regulation depending either on maternal or paternal gene origin. Bioinformatic analysis reveals that FEC between X:11AB and the other X chromosome bands correlates with the occurrence of short (~30 bp) identical DNA fragments partly homologous to Drosophila 372-bp satellite DNA repeat. Although learning acquisition in a conditioned courtship suppression paradigm is similar in hybrids, the middle-term memory formation shows patroclinic inheritance. Seemingly, this depends on changes in miR-974 expression. Several parameters of locomotion demonstrate heterosis. Our data indicate that the
agn
ts3
locus is capable of trans-regulating gene activity via POEs on the chromatin nuclear organization, thereby affecting behavior.
The relationship between structural features and selective transport properties of a polymer remains to be the topic of major interest among the scientists working in the field of membrane materials ...development. In the present work the structural and morphological features of the sulfonated co-polyimide and their role in the realisation of its selective transport properties are discussed. The features of the macromolecular chain having limitedly flexible -O-Ph-O- fragment and their influence on the properties of the material are studied with X-Ray diffraction analysis and differential scanning calorimetry. Microphase separated morphology of the block-co-polyimide was detected by the means of atomic force microscopy in the lateral force contrast mode. Theoretical and practical studies on the influence of the counterion nature on the block-copolymer morphology are conducted. Transport properties of the co-polyimide were investigated in the processes of pervaporation and gas separation. Morphological features of the copolymer allow the realisation of the selective fixed-site carrier facilitated transport in terms of pervaporation separation of various binary methanol mixtures. The polymer showed good separation performance in application to pervaporation separation of close to azeotropic MeOH/DMC and MeOH/DME mixtures reaching selectivity values close to 4. The relationship between real and ideal separation selectivities during PV of the studied mixtures are established. The lamellar-like morphology of the studied co-polyimide along with its other unique properties makes it perspective in application to fixed-site carrier facilitated pervaporation and gas separation membranes development.
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•Structural features of the chain having -O-Ph-O- flexible fragment are discussed.•Hansen solubility parameters of the sulfonated co-polyimide are determined.•Flory-Huggins theory is applied to describe the morphology of the co-polyimide.•High values of PV selectivity for methanol rich mixtures are achieved.•The model for the prediction of the real PV selectivity values is proposed.
The need to review the guidelines for the management of patients with multiple sclerosis using multiple sclerosis disease modifying drugs has become acute enough since the beginning of 2020 following ...the outbreak of the COVID-19 pandemic caused by a novel coronavirus SARS-CoV-2. Immunosuppressive drugs were also specifically addressed, as it is during administration of these drugs that the more severe course of COVID-19 disease was expected. Both the Russian and foreign teams published results of their research works. This article presents a retrospective analysis of the incidence rates of COVID-19 in patients with multiple sclerosis after selective immunosuppressive therapy with alemtuzumab and a clinical case when a patient was infected with coronavirus in the first days following the last infusion of the therapy course without clinical manifestations of the infectious disease. The author discusses the mechanisms underlying such a favourable outcome due to the CD52 lymphocyte depletion leading to the reduction of risks of developing hyperimmune reactions that underlie severe complications of COVID-19, and analyses previously published works of our foreign colleagues on the same theme. The review of the accumulated works and personal experience suggest that it is the CD52 lymphocyte depletion that makes it possible to avoid the cytokine storm and, as a result, the more severe course of COVID-19. Amidst the COVID-19 pandemic, during the prescription of multiple sclerosis disease modifying drugs, it should be borne in mind that patients should have access to all types of modern therapy and that the benefits should outweigh the sum of possible risks.
The signal pathway of actin remodeling, including LIM-kinase 1 (LIMK1) and its substrate cofilin, regulates multiple processes in neurons of vertebrates and invertebrates. Drosophila melanogaster is ...widely used as a model object for studying mechanisms of memory formation, storage, retrieval and forgetting. Previously, active forgetting in Drosophila was investigated in the standard Pavlovian olfactory conditioning paradigm. The role of specific dopaminergic neurons (DAN) and components of the actin remodeling pathway in different forms of forgetting was shown. In our research, we investigated the role of LIMK1 in Drosophila memory and forgetting in the conditioned courtship suppression paradigm (CCSP). In the Drosophila brain, LIMK1 and p-cofilin levels appeared to be low in specific neuropil structures, including the mushroom body (MB) lobes and the central complex. At the same time, LIMK1 was observed in cell bodies, such as DAN clusters regulating memory formation in CCSP. We applied GAL4 × UAS binary system to induce limk1 RNA interference in different types of neurons. The hybrid strain with limk1 interference in MB lobes and glia showed an increase in 3-h short-term memory (STM), without significant effects on long-term memory. limk1 interference in cholinergic neurons (CHN) impaired STM, while its interference in DAN and serotoninergic neurons (SRN) also dramatically impaired the flies' learning ability. By contrast, limk1 interference in fruitless neurons (FRN) resulted in increased 15-60 min STM, indicating a possible LIMK1 role in active forgetting. Males with limk1 interference in CHN and FRN also showed the opposite trends of courtship song parameters changes. Thus, LIMK1 effects on the Drosophila male memory and courtship song appeared to depend on the neuronal type or brain structure.
In this paper, we study the structure evolution of hafnium bronze undrer annealing after hardening and severe plastic deformation by two methods: dynamic channel-angular pressing (DCAP) and ...high-pressure torsion (HPT). Severe plastic deformation of hardened bronze is shown to lead to significant hardening. Under the annealing of bronze, additional hardening occurs due to the precipitation of Cu
5
Hf particles. The bronze structure after severe plastic deformation has a high thermal stability; the maximum hardness is achieved upon annealing at 400°C after DCAP and 300–400°C after HPT.
It was proposed that increased level of mitochondrial reactive oxygen species (ROS), mediating execution of the aging program of an organism, could also be critical for neoplastic transformation and ...tumorigenesis. This proposal was addressed using new mitochondria-targeted antioxidant SkQ1 (10-(6'-plastoquinonyl) decyltriphenylphosphonium) that scavenges ROS in mitochondria at nanomolar concentrations. We found that diet supplementation with SkQ1 (5 nmol/kg per day) suppressed spontaneous development of tumors (predominantly lymphomas) in p53⁻/⁻ mice. The same dose of SkQ1 inhibited the growth of human colon carcinoma HCT116/p53⁻/⁻ xenografts in athymic mice. Growth of tumor xenografts of human HPV-16-associated cervical carcinoma SiHa was affected by SkQ1 only slightly, but survival of tumor-bearing animals was increased. It was also shown that SkQ1 inhibited the tumor cell proliferation, which was demonstrated for HCT116 p53⁻/⁻ and SiHa cells in culture. Moreover, SkQ1 induced differentiation of various tumor cells in vitro. Coordinated SkQ1-initiated changes in cell shape, cytoskeleton organization, and E-cadherin-positive intercellular contacts were observed in epithelial tumor cells. In Ras- and SV40-transformed fibroblasts, SkQ1 was found to initiate reversal of morphological transformation of a malignant type, restoring actin stress fibers and focal adhesion contacts. SkQ1 suppressed angiogenesis in Matrigel implants, indicating that mitochondrial ROS could be important for tumor angiogenesis. This effect, however, was less pronounced in HCT116/p53⁻/⁻ tumor xenografts. We have also shown that SkQ1 and related positively charged antioxidants are substrates of the P-glycoprotein multidrug resistance pump. The lower anti-tumor effect and decreased intracellular accumulation of SkQ1, found in the case of HCT116 xenografts bearing mutant forms of p53, could be related to a higher level of P-glycoprotein. The effects of traditional antioxidant N-acetyl-L-cysteine (NAC) on tumor growth and tumor cell phenotype were similar to the effects of SkQ1 but more than 1,000,000 times higher doses of NAC than those of SkQ1 were required. Extremely high efficiency of SkQ1, related to its accumulation in the mitochondrial membrane, indicates that mitochondrial ROS production is critical for tumorigenesis at least in some animal models.
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