| 1. |
- Ali, Sharafat, et al.
(author)
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
- 2024
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In: Progress in Solid State Chemistry. - : Elsevier Ltd. - 0079-6786 .- 1873-1643.
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Journal article (peer-reviewed)abstract
- The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 °C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (α). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.
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| 2. |
- Ali, Sharafat, Associate Professor, 1976-, et al.
(author)
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
- 2024
-
In: Progress in Solid State Chemistry. - : Elsevier. - 0079-6786 .- 1873-1643. ; 74
-
Research review (peer-reviewed)abstract
- The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 degrees C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (alpha). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.
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| 3. |
- Gueguen, Yann, et al.
(author)
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Viscosity of high-nitrogen content Ca-Si-O-N glasses
- 2010
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In: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 30:16, s. 3455-3458
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Journal article (peer-reviewed)abstract
- The viscosity of three high-nitrogen content Ca-Si-O-N glasses, with 30-58 e/o N and 36-39 e/o Ca, was determined by micro-indentation. The measurements were made using an automated set-up, designed and built in-house, capable of measurements up to 1200 degrees C with applied loads of 0.01-15 N. The viscosity increases significantly with the nitrogen content and reaches viscosity values close to reported values for rare-earth silica oxynitride glasses. The glass transition temperatures range between 878 and 995 degrees C and are in very good agreement with values measured by differential thermal analysis. The apparent viscosity activation energies are very high, ranging from 855 to 2170 kJ/mol. The glasses can accordingly be classified as being both very refractory and very fragile. Implications of the viscosity values and mechanical properties of the glasses for their structures are discussed.
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| 4. |
- Hall, Janet, et al.
(author)
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Ionizing radiation biomarkers in epidemiological studies - An update
- 2017
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In: Mutation Research. - : Elsevier BV. - 1383-5742 .- 1388-2139. ; 771, s. 59-84
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Research review (peer-reviewed)abstract
- Recent epidemiology studies highlighted the detrimental health effects of exposure to low dose and low dose rate ionizing radiation (IR): nuclear industry workers studies have shown increased leukaemia and solid tumour risks following cumulative doses of < 100 mSv and dose rates of < 10 mGy per year; paediatric patients studies have reported increased leukaemia and brain tumours risks after doses of 30-60 mGy from computed tomography scans. Questions arise, however, about the impact of even lower doses and dose rates where classical epidemiological studies have limited power but where subsets within the large cohorts are expected to have an increased risk. Further progress requires integration of biomarkers or bioassays of individual exposure, effects and susceptibility to IR. The European DoReMi (Low Dose Research towards Multidisciplinary Integration) consortium previously reviewed biomarkers for potential use in IR epidemiological studies. Given the increased mechanistic understanding of responses to low dose radiation the current review provides an update covering technical advances and recent studies. A key issue identified is deciding which biomarkers to progress. A roadmap is provided for biomarker development from discovery to implementation and used to summarise the current status of proposed biomarkers for epidemiological studies. Most potential biomarkers remain at the discovery stage and for some there is sufficient evidence that further development is not warranted. One biomarker identified in the final stages of development and as a priority for further research is radiation specific mRNA transcript profiles.
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