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- Grinchuk, P. S., et al.
(författare)
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Effect of technological parameters on densification of reaction bonded Si/SiC ceramics
- 2018
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Ingår i: Journal of the European Ceramic Society. - : Elsevier Ltd. - 0955-2219 .- 1873-619X. ; 38:15, s. 4815-4823
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Tidskriftsartikel (refereegranskat)abstract
- Si/SiC composite ceramics was produced by reaction sintering method in process of molten silicon infiltration into porous C/SiC preform fabricated by powder injection molding followed by impregnation with phenolic resin and carbonization. To optimize the ceramics densification process, effect of slurry composition, debinding conditions and the key parameters of all technological stages on the Si/SiC composite characteristics was studied. At the stage of molding the value of solid loading 87.5% was achieved using bimodal SiC powder and paraffin-based binder. It was found that the optimal conditions of fast thermal debinding correspond to the heating rate of 10 °C/min in air. The porous C/SiC ceramic preform carbonized at 1200 °C contained 4% of pyrolytic carbon and ∼25% of open pores. The bulk density of Si/SiC ceramics reached 3.04 g/cm3, silicon carbide content was 83–85 wt.% and residual porosity did not exceed 2%.
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- Alshahrani, M. A.M., et al.
(författare)
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High-Temperature Hydrogen Attack on 2.25Cr-1Mo Steel: The Roles of Residual Carbon, Initial Microstructure and Carbide Stability
- 2022
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Ingår i: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science. - : Springer Science and Business Media LLC. - 1073-5623. ; 54, s. 3682-
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Tidskriftsartikel (refereegranskat)abstract
- High temperature hydrogen attack is a damage mechanism that occurs in critical steel components in petrochemical plants and refineries when the hydrogen penetrates the steel and reacts with the carbides within to produce pores containing methane. With the motivation of understanding the role of carbide stability on the reaction with hydrogen, samples of a classic 214Cr-1Mo steel were subjected to a variety of heat treatments that generate a corresponding variety of precipitates, prior to exposure to high-pressure hydrogen in an autoclave. Using quantitative carbide, porosity and microstructural characterisation, it has been possible to demonstrate the roles of four variables: (a) the carbon residue present in the ferrite; (b) the non-equilibrium chemical composition of carbide; (c) the fraction of the carbide that is closest to the thermodynamic equilibrium state and (d) the initial microstructural state, i.e., whether it is martensitic or bainitic prior to heat treatment.
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- Solovei, D. V., et al.
(författare)
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Synthesis of Reinforced Ceramic Matrix Composite Based on SiC and Nanocarbon Mesh
- 2019
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Ingår i: Journal of Engineering Physics and Thermophysics. - : Springer New York LLC. - 1062-0125 .- 1573-871X. ; 92:4, s. 1016-1024
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Tidskriftsartikel (refereegranskat)abstract
- Most modern matrix composite materials employ a variety of carbon nanofillers to improve their mechanical, electrical, and functional properties. Nanofillers are separately implanted into the initial ceramic matrix, which complicates the composite manufacturing technology and increases the final cost. In this work, the synthesis of nanocarbon fillers was carried out using high-temperature (1200°C) pyrolysis of phenolic resin directly inside the silicon carbide matrix. This results in the formation of a continuous 3D nanocarbon mesh uniformly binding and reinforcing the final product throughout the volume. The nanocarbon filler synthesized in the SiC matrix contains two allotropic carbon forms: nanographite and nanofibers. The study of the features of the carbon structure and morphology showed that during the pyrolysis the multilayered nanographite structures had been formed on the surface of SiC grains of average crystallite size equal to 20–35 nm. In the matrix pores, carbon nanofibers a few micrometers in length and 20–40 nanometers in diameter are synthesized. The reiteration of the phenolic resin impregnation–pyrolysis cycle increased the free carbon content from 4 to 7 wt.% for once and twice impregnated and pyrolyzed samples, respectively, and the Young's modulus, from 50.7 to 94.3 GPa. The obtained carbon content and structure are appropriate to produce C/SiC composite for application of ceramics and electrodes.
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- Shahzadi, I., et al.
(författare)
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Hydrothermal Synthesis of Fe-Doped Cadmium Oxide Showed Bactericidal Behavior and Highly Efficient Visible Light Photocatalysis
- 2023
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Ingår i: ACS Omega. - 2470-1343. ; 8:33, s. 30681-30693
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Tidskriftsartikel (refereegranskat)abstract
- Cationic dyes presentin industrial effluents significantlyreducethe effectiveness of remediation operations. Considering the terribleimpact of these pollutants on environment and biodiversity, investigatingstrategies to remove potentially harmful compounds from water is becomingan increasingly intriguing issue. In this work, we employed a simplehydrothermal technique to synthesize Fe-doped CdO (2, 4, and 6 wt%) nanostructures and assessed their efficacy in degrading methyleneblue (MB) dye and inhibiting the growth of Staphylococcusaureus and Escherichia coli, respectively. Structural, morphological, and optical characterizationof produced nanomaterials was also performed using X-ray diffraction,TEM, and UV absorption spectra. The photocatalytic decomposition ofMB was significantly enhanced (58.8%) by using Fe (6 wt %)-doped CdOcatalysts for 80 min under irradiation. In addition, 2.05-5.05mm inhibitory zones were seen against Gram-positive bacteria (S. aureus), whereas the range for Gram-negative bacteria(E. coli) was 1.65-2.75 mm.These nanostructures were shown to be very effective inhibitors ofbeta-lactamase, d-alanine-d-alanine ligase B, andfatty acid synthase inhibitor by in silico molecular docking investigations.
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- Abdelkader, Ehab, et al.
(författare)
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Analysis of retinal structure and function in cone dystrophy with supernormal rod response
- 2020
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Ingår i: Documenta Ophthalmologica. - : Springer Science and Business Media LLC. - 0012-4486 .- 1573-2622.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To report the clinical and electrophysiological features of cone dystrophy with supernormal rod response (CDSRR). Methods: Retrospective cohort study of 15 unrelated patients (nine males and six females, median age 16, range 5–47 years) diagnosed with CDSRR by clinical examination, full-field electroretinography (ERG) and genetic testing. Observations: History, ophthalmic examination including near vision, color vision and contrast sensitivity assessment, multimodal retinal imaging and ERG. Genetic testing was done for all patients using next-generation sequencing. Results: The rate of consanguinity was 86.7%. Color vision was defective in 56.3%. Near vision was defective in all patients (mean 20/160). Contrast sensitivity was affected in all patients at low contrast of 2.5%. A parafoveal ring of increased autofluorescence imaging was seen in most patients (75%). Supernormal mixed maximal response b-wave was seen bilaterally in 63% of patients (and high normal in 37%). Rod dysfunction with prolonged rod b-wave latency was detected in all. The 30-Hz flicker response was more reduced and delayed compared to the single-flash cone response. A novel homozygous missense variant c.530G>C (p.Cys177Ser) in KCNV2 was detected in one patient, the nonsense homozygous mutation c.427G>T (p.Glu143*) was found in 13 patients, and the nonsense c.159C>G (p.Tyr53*) was found in one patient. Conclusion: This is the largest cohort of CDSRR from a single ethnic background. Rod dysfunction and reduced 30-Hz flicker response were demonstrated in all patients. In contrast to previous descriptions in the literature, a supernormal combined dark-adapted rod-cone ERG was present in the majority of the patients at standard stimulus intensity. Considering the consistent genotype and the demonstration of likely pathogenic genetic variants in all the patients, we argue that the combination of delayed rod b-wave and subnormal flicker response strongly suggests the diagnosis of CDSRR.
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- Hussain, Nadia, et al.
(författare)
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Cichorium intybus L. significantly alleviates cigarette smoke-induced acute lung injury by lowering NF-κB pathway activation and inflammatory mediators
- 2023
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Ingår i: Heliyon. - : Elsevier. - 2405-8440. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Cigarette smoke (CS) is one of the primary causes of acute lung injury (ALI) via provoking pulmonary inflammation and oxidative stress. Despite substantial studies, no effective treatment for ALI is presently available.Purpose: New prospective treatment options for ALI are required. Thus, this project was designed to investigate the in vivo and in vitro protective effects of 70 % methanolic-aqueous crude extract of whole plant of Cichorium intybus (Ci.Mce) against CS-induced ALI.Study design: /methods: Initially, male Swiss albino mice were subjected to whole-body CS exposure for 10 continuous days to prepare CS-induced ALI models. Normal saline (10 mL/kg), Ci.Mce (100, 200, 300 mg/kg), and Dexamethasone (1 mg/kg) were orally administered to respective animal groups 1 h prior to CS-exposure. 24 hrs after the last CS-exposure, BALF and lungs were harvested to study the key characteristics of ALI. Next, HPLC analysis was done to explore the phytoconstituents.Results: Ci.Mce exhibited significant reductions in lung macrophage and neutrophil infiltration, lung weight coefficient, and albumin exudation. Additionally, it effectively ameliorated lung histopathological alterations and hypoxemia. Notably, Ci.Mce exerted inhibitory effects on the excessive generation of IL-6, IL-1β, and KC in both CS-induced ALI murine models and CSE-stimulated RAW 264.7 macrophages. Noteworthy benefits included the attenuation of oxidative stress induced by CS, evidenced by decreased levels of MDA, TOS, and MPO, alongside enhanced TAC production. Furthermore, Ci.Mce demonstrated a marked reduction in CS-induced NF-κB expression, both in vivo and in vitro.Conclusion: Consequently, Cichorium intybus could be a therapeutic option for CS-induced ALI due to its ability to suppress inflammatory reactions, mitigate oxidative stress, and quell NF-κB p65 activation.
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