65,897 research outputs found
Magnesium-based glasses prepared by sol-gel processing for use as supplementary cementitious materials
No full textAbstract
For decades, supplementary cementitious materials (SCMs) have been utilized as clinker substitutes as one of the strategies to mitigate the CO2 emissions associated with Portland cement production. However, traditional SCMs (e.g., coal fly ash, silica fume, and blast furnace slag) are being phased out, as they are insufficient to enable high volume clinker substitution. Therefore, alternative SCMs are actively being sought to meet market demand. Synthetic glasses may be a potential source of SCMs due to their pozzolanic activity and tunable properties. The chemical composition of glasses determines their pozzolanic activity, with Ca-based glasses being predominantly studied owing to their high reactivity. However, this leads to the same inherent CO2 emissions as for cement, originating from the production of CaO from CaCO3.
This thesis investigates Mg-based silicate glasses synthesized via the sol-gel method, tuning their composition for higher pozzolanic activity. The feasibility of using Mg-based silicate glasses as SCMs was studied through three main pathways:
(1) Development of a binary Mg-Si sol-gel glass system: The impact of varying Mg concentrations on the glass reactivity was assessed (Publication Ⅰ).
(2) Introduction of Fe into the Mg-Si system: Varying concentrations of Fe3+/ Fe2+ were incorporated into Mg-Si glasses, investigating changes in reactivity (Publications Ⅱ, Ⅲ).
(3) Assessment of cementitious performance: The pozzolanic activity of Mg-based glasses was evaluated, and their impact on the properties and performance of cementitious systems was studied (Publication Ⅳ).
The research revealed the high elemental solubility of the synthetic glasses, indicating their high reactivity, and demonstrated pozzolanic activity exceeding that of conventional SCMs such as fly ash slag. These findings provide a preliminary assessment of the potential for using Mg silicate glasses as novel SCMs with the aim of reducing CO2 emissions. Original papers Jiang, C., Ramteke, D. D., Li, J., Sliz, R., Sreenivasan, H., Cheeseman, C., & Kinnunen, P. (2023). Preparation and characterization of binary Mg-silicate glasses via Sol-Gel route. Journal of Non-Crystalline Solids, 606, 122204. https://doi.org/10.1016/j.jnoncrysol.2023.122204 https://doi.org/10.1016/j.jnoncrysol.2023.122204 Self-archived version Jiang, C., Santos, H. S., Yliniemi, J., Lindén, J., Ramteke, D. D., Illikainen, M., Cheeseman, C., & Kinnunen, P. (2024). Fe-bearing magnesium silicate glasses for potential supplementary cementitious applications. Frontiers in Materials, 11, 1509403. https://doi.org/10.3389/fmats.2024.1509403 https://doi.org/10.3389/fmats.2024.1509403 Self-archived version Jiang, C., Yliniemi, J., Santos, H. S., Lindén, J., Ramteke, D.D., Cheeseman, C., & Kinnunen, P. (2024). Optimizing Fe(II)/Fe(III)-bearing magnesium silicate glasses for applications in supplementary cementitious materials. Manuscript submitted for publication. Jiang, C., Santos, H. S., Ahmad, L., Yliniemi, J., Cheeseman, C., & Kinnunen, P. (2025). Properties of Fe-bearing Mg silicate glasses as novel supplementary cementitious materials. Manuscript submitted for publication. Tiivistelmä
Jo vuosikymmenten ajan sementin seosaineita (SCM) on käytetty klinkkerin korvikkeina tavoitteena vähentää portlandsementin tuotannossa syntyviä CO2-päästöjä. Perinteisten SCM-materiaalien, kuten lentotuhkan, silikajauheen ja masuunikuonan, saatavuus ei kuitenkaan riitä mahdollistamaan korkeaa klinkkerin korvausastetta. Siksi on tarpeen kehittää uusia SCM-materiaaleja markkinoiden tarpeiden täyttämiseksi. Synteettiset lasit voivat olla potentiaalinen vaihtoehto niiden potsolaanisen aktiivisuuden ja säädettävien ominaisuuksien ansiosta. Lasien kemiallinen koostumus määrittää niiden potsolaanisen aktiivisuuden, ja enimmäkseen on tutkittu Ca-pohjaisia laseja niiden korkean reaktiivisuuden vuoksi. Tämä johtaa kuitenkin samoihin luontaisiin CO2-päästöihin kuin sementin tuotannossa, koska CaO:ta tuotetaan CaCO3:sta.
Tämä väitöskirja tutkii Mg-pohjaisia silikaattilaseja, jotka tuotetaan sol-gel-menetelmällä, jossa lasien koostumusta säädetään korkeamman potsolaanisen aktiivisuuden saavuttamiseksi. Mg-pohjaisten silikaattilasien käyttökelpoisuutta SCM-materiaaleina tutkittiin kolmen pääasiallisen lähestymistavan kautta:
(1) Binaarisen Mg-Si sol-gel-lasin kehitys: Eri Mg-pitoisuuksien vaikutuksia lasin reaktiivisuuteen arvioitiin (julkaisu I).
(2) Fe:n lisääminen Mg-Si-järjestelmään: Mg-Si-laseihin lisättiin eri pitoisuuksia Fe3+/Fe2+:aa, ja niiden vaikutusta reaktiivisuuteen tutkittiin (julkaisut II, III).
(3) Sementtimäisen suorituskyvyn arviointi: Mg-pohjaisten lasien potsolaanista aktiivisuutta arvioitiin, ja niiden vaikutusta seostettujen sementtien ominaisuuksiin ja suorituskykyyn tutkittiin (julkaisu IV).
Tutkimus paljastaa synteettisten lasien korkean alkuaineliukoisuuden, mikä viittaa niiden korkeaan reaktiivisuuteen, sekä osoittaa, että niiden potsolaaninen aktiivisuus ylittää perinteiset SCM:t, kuten lentotuhkan ja kuonan. Nämä havainnot tarjoavat alustavan arvion Mg-silikaattilasien potentiaalista uusina SCM-materiaaleina, joiden tavoitteena on CO2-päästöjen vähentäminen. Osajulkaisut Jiang, C., Ramteke, D. D., Li, J., Sliz, R., Sreenivasan, H., Cheeseman, C., & Kinnunen, P. (2023). Preparation and characterization of binary Mg-silicate glasses via Sol-Gel route. Journal of Non-Crystalline Solids, 606, 122204. https://doi.org/10.1016/j.jnoncrysol.2023.122204 https://doi.org/10.1016/j.jnoncrysol.2023.122204 Rinnakkaistallennettu versio Jiang, C., Santos, H. S., Yliniemi, J., Lindén, J., Ramteke, D. D., Illikainen, M., Cheeseman, C., & Kinnunen, P. (2024). Fe-bearing magnesium silicate glasses for potential supplementary cementitious applications. Frontiers in Materials, 11, 1509403. https://doi.org/10.3389/fmats.2024.1509403 https://doi.org/10.3389/fmats.2024.1509403 Rinnakkaistallennettu versio Jiang, C., Yliniemi, J., Santos, H. S., Lindén, J., Ramteke, D.D., Cheeseman, C., & Kinnunen, P. (2024). Optimizing Fe(II)/Fe(III)-bearing magnesium silicate glasses for applications in supplementary cementitious materials. Manuscript submitted for publication. Jiang, C., Santos, H. S., Ahmad, L., Yliniemi, J., Cheeseman, C., & Kinnunen, P. (2025). Properties of Fe-bearing Mg silicate glasses as novel supplementary cementitious materials. Manuscript submitted for publication. Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Technology and Natural Sciences of the University of Oulu for public defence in the Wetteri auditorium (IT115), Linnanmaa, on 25 April 2025, at 12 noonAbstract
For decades, supplementary cementitious materials (SCMs) have been utilized as clinker substitutes as one of the strategies to mitigate the CO2 emissions associated with Portland cement production. However, traditional SCMs (e.g., coal fly ash, silica fume, and blast furnace slag) are being phased out, as they are insufficient to enable high volume clinker substitution. Therefore, alternative SCMs are actively being sought to meet market demand. Synthetic glasses may be a potential source of SCMs due to their pozzolanic activity and tunable properties. The chemical composition of glasses determines their pozzolanic activity, with Ca-based glasses being predominantly studied owing to their high reactivity. However, this leads to the same inherent CO2 emissions as for cement, originating from the production of CaO from CaCO3.
This thesis investigates Mg-based silicate glasses synthesized via the sol-gel method, tuning their composition for higher pozzolanic activity. The feasibility of using Mg-based silicate glasses as SCMs was studied through three main pathways:
(1) Development of a binary Mg-Si sol-gel glass system: The impact of varying Mg concentrations on the glass reactivity was assessed (Publication Ⅰ).
(2) Introduction of Fe into the Mg-Si system: Varying concentrations of Fe3+/ Fe2+ were incorporated into Mg-Si glasses, investigating changes in reactivity (Publications Ⅱ, Ⅲ).
(3) Assessment of cementitious performance: The pozzolanic activity of Mg-based glasses was evaluated, and their impact on the properties and performance of cementitious systems was studied (Publication Ⅳ).
The research revealed the high elemental solubility of the synthetic glasses, indicating their high reactivity, and demonstrated pozzolanic activity exceeding that of conventional SCMs such as fly ash slag. These findings provide a preliminary assessment of the potential for using Mg silicate glasses as novel SCMs with the aim of reducing CO2 emissions.Tiivistelmä
Jo vuosikymmenten ajan sementin seosaineita (SCM) on käytetty klinkkerin korvikkeina tavoitteena vähentää portlandsementin tuotannossa syntyviä CO2-päästöjä. Perinteisten SCM-materiaalien, kuten lentotuhkan, silikajauheen ja masuunikuonan, saatavuus ei kuitenkaan riitä mahdollistamaan korkeaa klinkkerin korvausastetta. Siksi on tarpeen kehittää uusia SCM-materiaaleja markkinoiden tarpeiden täyttämiseksi. Synteettiset lasit voivat olla potentiaalinen vaihtoehto niiden potsolaanisen aktiivisuuden ja säädettävien ominaisuuksien ansiosta. Lasien kemiallinen koostumus määrittää niiden potsolaanisen aktiivisuuden, ja enimmäkseen on tutkittu Ca-pohjaisia laseja niiden korkean reaktiivisuuden vuoksi. Tämä johtaa kuitenkin samoihin luontaisiin CO2-päästöihin kuin sementin tuotannossa, koska CaO:ta tuotetaan CaCO3:sta.
Tämä väitöskirja tutkii Mg-pohjaisia silikaattilaseja, jotka tuotetaan sol-gel-menetelmällä, jossa lasien koostumusta säädetään korkeamman potsolaanisen aktiivisuuden saavuttamiseksi. Mg-pohjaisten silikaattilasien käyttökelpoisuutta SCM-materiaaleina tutkittiin kolmen pääasiallisen lähestymistavan kautta:
(1) Binaarisen Mg-Si sol-gel-lasin kehitys: Eri Mg-pitoisuuksien vaikutuksia lasin reaktiivisuuteen arvioitiin (julkaisu I).
(2) Fe:n lisääminen Mg-Si-järjestelmään: Mg-Si-laseihin lisättiin eri pitoisuuksia Fe3+/Fe2+:aa, ja niiden vaikutusta reaktiivisuuteen tutkittiin (julkaisut II, III).
(3) Sementtimäisen suorituskyvyn arviointi: Mg-pohjaisten lasien potsolaanista aktiivisuutta arvioitiin, ja niiden vaikutusta seostettujen sementtien ominaisuuksiin ja suorituskykyyn tutkittiin (julkaisu IV).
Tutkimus paljastaa synteettisten lasien korkean alkuaineliukoisuuden, mikä viittaa niiden korkeaan reaktiivisuuteen, sekä osoittaa, että niiden potsolaaninen aktiivisuus ylittää perinteiset SCM:t, kuten lentotuhkan ja kuonan. Nämä havainnot tarjoavat alustavan arvion Mg-silikaattilasien potentiaalista uusina SCM-materiaaleina, joiden tavoitteena on CO2-päästöjen vähentäminen
Characterising the sintering behaviour of pulverised fuel ash using heating stage microscopy
No full textPolarizable Embedding Approach for the Analytical Calculation of Raman and Raman Optical Activity Spectra of Solvated Systems
No full textWe present an analytical formulation and implementation of Raman and Raman Optical Activity (ROA) spectra within a three-layer fully polarizable Quantum Mechanical (QM)/ Molecular Mechanics (MM)/Polarizable Continuum Model (PCM) approach. Polarization effects in the MM layer are modeled by exploiting the Fluctuating Charges (FQ) method, in which MM solvent atoms are endowed with electric charges that can be mutually polarized by the solute QM density. Because of its fully polarizable atomistic description, QM/FQ/PCM is able to account for specific solvent effects like those due to hydrogen bonds, providing a physical picture for protic solvents such as water. Applications to aqueous (R)-methyloxirane and (S)-methyllactate are presented, and results are compared with available experimental data
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Sintering anisotropy and shape distortion during viscous flow sintering: the case of glass matrix composites and glass-ceramics
No full textIn "Book of abstracts" and oral presentatio
Study of the sintering mechanism of pulverised fuel ash using heating stage microscopy
No full textIn "Book of abstracts" and presentatio
Business law: Ethical International and E-Commerce Environment, 4th ed/ Cheeseman
No full textXXXII, 1200hal.: ill.,tab.: 26 c
Business law: Ethical International and E-Commerce Environment, 4th ed/ Cheeseman
No full textXXXII, 1200hal.: ill.,tab.: 26 c
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Population Ecology of Thelymitra matthewsii Cheeseman Orchidaceae, in Northern New Zealand
No full textThe terrestrial orchid Thelymitra matthewsii Cheeseman, uncommon in New Zealand, was studied to increase knowledge of the species life cycle, morphology and ecology. Results will enhance future conservation management for the species.
New information related to the morphology of T. matthewsii was obtained. The species was found to emerge in one of four discrete life stages of distinctive morphology and height range that remained constant for the season, not developing into a more advanced life stage. The leaf of the three pre adult life stages designated a hook, a spiral, and a non flowering stage, did not inflate at the base, but rose smoothly from the tuber. Apparent morphological differences in the column between descriptions of the Australian taxon and the small New Zealand sample examined suggested further study was needed.
Comprehensive monthly monitoring was carried out at five study sites in three locations in the Te Paki area of the Far North, from 2002 to 2004. No patterns emerged in plant life stage succession, flowering, and presence or absence at labels reinforcing the concept that variability was a common component of the population census.
Seasonal and partial absence was a major component of the populations. An average of 32.8% of plants, over five study sites, were present throughout three seasons, while 66.9% were recorded as absent (not visible) at monitoring. New plants appearing in 2003 and 2004 showed a high percentage of subsequent absence (mean 85.7%).
To determine population stability, recruitment and absence were compared. Plant absence exceeded recruitment by 7% (mean plant absence 30.5%; mean recruitment 23.4%). Plants continued to appear during the monitoring period, and labeled plants increased two-fold over commencement numbers.
Adults recorded as 28% of labeled plants over three seasons, were out numbered by pre-flowering stages. Only 5% of population numbers exhibited succession from a smaller to a flowering plant. Life stage modeling indicated a life stage was more likely to be followed by the same stage than an expected successive stage.
Thelymitra matthewsii was found to be present in four substrates in the Far North.
The survey of vegetation found the indigenous species Kunzea ericoides and the exotic Hakea gibbosa dominant for both height, and cover. Litter and bare ground dominated ground cover. Differences in vegetation and ground cover, of sites supporting T. matthewsii and comparison sites that did not, were minor and suggested that another factor, for example a suitable fungal partner, influenced the species presence or absence.
The results of the study indicated the present threat classification of Thelymitra matthewsii is inadequate in the light of the species relatively circumscribed, widely separated habitats, the small number of reproducing individuals and vulnerability to habitat modification
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