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2025
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2025
Liquid metal is widely used as the primary coolant in many advanced nuclear energy systems. Prandtl number of liquid metal is much lower than that of the conventional coolant of water or gas. Based on the Reynolds analogy, the turbulent Prandtl number is assumed to be a constant around unity. For the turbulent convection of liquid metal, dissipations of half the temperature variance are larger than those of turbulent kinetic energies. The dissimilarity between the thermal and momentum fields increases as Pr decreases. The turbulent Prandtl number is larger than one for the liquid metal. In the current investigation, the turbulent convection of liquid metal in the channel is quasi-directly simulated with OpenFOAM-7. The turbulent statistics of the momentum and the thermal field are compared with the existing database to validate the numerical model. The power law for dimensionless temperature distribution with different Prandtl numbers is obtained by regression analysis of numerical results. A new Nusselt number correlation is derived based on the power law. The new Nusselt number correlation agrees well with the DNS results in the literature. The momentum mixing process between different layers in the cross section is compared with the thermal mixing process. The effects of the Prandtl number on the difference between the turbulence time scale and scalar time scale are analyzed. A new turbulent Prandtl number model with local parameters is obtained for turbulent convection with liquid metal. Combined with the k−ω model, the temperature distributions with the new turbulent Prandtl number model agree well with the DNS results in the literature. The new turbulent Prandtl number model can be used for turbulent convection with different Prandtl and different Reynolds numbers.- Book : 18(3)
- Pub. Date : 2025
- Page : pp.547-547
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2025
The paper describes changes in the structure, morphology, mechanical and thermal properties of porous film samples of poly(4,4′-oxidiphenylene)pyromellitimide prepared as a result of selective destruction of urethane blocks in copolymers composed of pyromellitimide blocks and polyurethane blocks. The initial samples of the new composition of statistical copoly(urethane-imide)s (CoPUIs) were prepared via polycondensation methods using pyromellitic dianhydride (PMDA), 4,4′-oxidyaniline (ODA), 2,4-toluylenediisocyanate (TDI), as well as polycaprolactone (PCL) and poly(1,6-hexanediol/neopentylglycol-alt-adipic acid) (ALT) as monomers. The molar ratio of imide and polyurethane blocks in CoPUI was 10:1. The initial films were heated up to 170 °C to complete the polycondensation processes, after which they were subjected to thermolysis and hydrolysis. The thermolysis (thermal degradation) of copolymers was carried out by heating the initial samples to temperatures of 300 °C or 350 °C. Then, the thermolized films were subjected to chemical degradation in hydrolytic baths containing an aqueous solution of potassium hydroxide. As a result, urethane blocks were destroyed and removed from the polymer. The resulting products practically did not contain polyurethane links and, in chemical composition, were practically identical to poly(4,4′-oxidiphenylene)pyromellitimide. NMR and IR spectroscopy, atomic force microscopy, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical analysis and mechanical properties testing were used to determine the differences in the structure and properties of the initial copolymers and targeted products. The effect of the conditions of destructive processes on the structure, morphology and mechanical properties of the obtained porous polyimide films was determined. From a practical point of view, the final porous films are promising as membranes for filtering aggressive amide solvents at high temperatures.- Book : 17(3)
- Pub. Date : 2025
- Page : pp.329-329
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2025
The author studied in detail the aspects of cooperation between Russia and Brazil in the field of green energy. In this context, Russia and Brazil, as countries with vast territories and rich natural resources, have a special potential for developing the green energy sector both within the framework of each country's energy policy separately and in bilateral cooperation. Both countries are expanding the possibilities of using various types of renewable energy sources, and therefore cooperation between these two states can become an important factor in promoting this direction in global realities. The countries are actively strengthening cooperation within the framework of the BRICS, because one of the relevant topics on the agenda of the association is precisely cooperation in the field of green energy and the economy. The partnership between the two countries not only contributes to achieving carbon neutrality, but also creates favorable conditions for further economic growth. The main research method is system analysis, which reveals the components of the countries' cooperation policies in the field of green energy, and the green energy of Russia and Brazil are considered separately. A geo-economic approach was also used to identify the dependencies of the development of low-carbon markets in Russia and Brazil on the common agenda of such an association as the BRICS. The scientific novelty of the study lies in an extensive analysis of cooperation between the Russian Federation and Brazil in the field of green initiatives, including the creation of low-carbon markets, the use of renewable energy sources, as well as the promotion of climate and carbon-neutral initiatives of the two countries through the BRICS. The article examines this aspect of cooperation between the two countries, since when analyzing energy cooperation between Russia and Brazil, researchers more often focus on carbon energy resources. The two countries are strengthening cooperation in the field of green innovation, creating joint projects in the field of nuclear and hydrogen energy and contributing to the sustainable development of the two countries. The countries are actively strengthening cooperation within the framework of the BRICS, because one of the relevant topics on the agenda of the association is precisely cooperation in the field of green energy and the economy. The partnership between the two countries not only contributes to achieving carbon neutrality, but also creates favorable conditions for further economic growth.
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2025
Progestogens’ anti-anxiety and anti-depressive effects and mechanisms are not well-understood. Progestogens are hypothesized to have anti-anxiety and anti-depressive effects on behavior, independent of actions at nuclear progestin receptors (NPRs) and dependent on allopregnanolone (5α-pregnan-3α-ol-20-one; 3α,5α-THP), a 5α-reduced, neuroactive metabolite of progesterone (P4). Adult c57 mice in behavioral estrus (proestrus; pro) showed more anti-anxiety-like and anti-depressant-like behavior and higher levels of estradiol (E2), P4, and allopregnanolone in the hippocampus/amygdala complex. Proestrus c57 > 5α-reductase knockout (5αRKO) mice made more central entries in an open field than diestrus c57 and 5αRKO mice that were not different. Ovariectomized (OVX) c57 mice administered 1, 2, or 4 mg/kg P4 SC showed dosage-dependent increases in central entries in an open field (more anti-anxiety-like behavior); 5αRKO mice had maximal increases at 1–2 mg/kg P4. OVX c57 and 5αRKO mice showed maximum increases in central entries with SC 3α,5α-THP (4 mg/kg), and c57s showed a similar maximal response to P4 (4 mg/kg), but 5αRKOs response was half at that dosage. P4 (4 mg/kg SC to OVX c57 or progestin receptor knockout (PRKO) mice decreased immobility (depression-like behavior) in the forced swim task. Effects of E2 and veh were similar in both groups. Levels of 3α,5α-THP in the hippocampus/amygdala were consistent with effects on central entries in the open field. Levels of brain-derived neurotrophic factor (BDNF) in the hippocampus/amygdala were greater among E2-primed (0.09 mg/kg, SC) vs vehicle-administered mice. In sum, adult female mice can be responsive to P4 for anti-anxiety/anti-depressant-like behavior; such effects may be independent of NPRs but require 5α-reduction and E2’s priming actions at BDNF in the hippocampus/amygdala complex.- Book : 26(3)
- Pub. Date : 2025
- Page : pp.1173-1173
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2025
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2025
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2025
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2025
ABSTRACTBackgroundSpinal muscular atrophy (SMA) is a health‐ and life‐limiting neuromuscular disorder. Although varying degrees of mitochondrial abnormalities have been documented in SMA skeletal muscle, the influence of disease progression on pathways that govern organelle turnover and dynamics are poorly understood. Thus, the purpose of this study was to investigate skeletal muscle mitochondria during SMA disease progression and determine the effects of therapeutic modalities on organelle biology.MethodsSmn2B/+ and Smn2B/− severe SMA‐like mice were used to investigate mitochondrial turnover and dynamics signalling. Muscles were analysed at postnatal day 9 (P9), P13 or P21 to address pre‐symptomatic, early symptomatic and late symptomatic periods of the disorder. Additionally, we utilized an acute dose of exercise and urolithin A (UA) to stimulate organelle remodelling in skeletal muscle of SMA mice in vivo and in SMA patient‐derived myotubes in vitro, respectively.ResultsSmn2B/+ and Smn2B/− mice demonstrated similar levels of muscle mitochondrial oxidative phosphorylation (OxPhos) proteins throughout disease progression. In contrast, at P21 the mRNA levels of upstream factors important for the transcription of mitochondrial genes encoded by the nuclear and mitochondrial DNA, including nuclear respiratory factor 2, sirtuin 1, mitochondrial transcription factor A and tumour protein 53, were upregulated (+31%–195%, p < 0.05) in Smn2B/− mice relative to Smn2B/+. Early and late symptomatic skeletal muscle from SMA‐like mice showed greater autophagosome formation as denoted by more phosphorylated autophagy related 16‐like 1 (p‐ATG16L1Ser278) puncta (+60%–80%, p < 0.05), along with a build‐up of molecules indicative of damaged mitochondria such as BCL2 interacting protein 3, Parkin and PTEN‐induced kinase 1 (+100%–195%, p < 0.05). Furthermore, we observed a fragmented mitochondrial phenotype at P21 that was concomitant with abnormal splicing of Optic atrophy 1 transcripts (−53%, p < 0.05). A single dose of exercise augmented the expression of citrate synthase (+43%, p < 0.05) and corrected the over‐assembly of autophagosomes (−64%, p < 0.05). In patient muscle cells, UA treatment stimulated autophagic flux, increased the expression of OxPhos proteins (+15%–47%, p < 0.05) and improved maximal oxygen consumption (+84%, p < 0.05).ConclusionsAbnormal skeletal muscle mitochondrial turnover and dynamics are associated with disease progression in Smn2B/− mice despite compensatory elevations in upstream factors important for organelle synthesis and recycling. Exercise and UA enhance mitochondrial health in skeletal muscle, which indicates that lifestyle‐based and pharmacological interventions may be effective countermeasures targeting the organelle for therapeutic remodelling in SMA.- Book : 16(1)
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