| 1. |
- Bring, Torun, et al.
(författare)
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Potassium sulfate droplets and the origin of turbidity in alabaster glass
- 2006
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Ingår i: Glass Technology : European Journal of Glass Science and Technology A. ; 47:1, s. 15-18
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Tidskriftsartikel (refereegranskat)abstract
- A study of the criteria required to manufacture multi-component semi-transparent silicate glasses, so called “alabaster” glass, has found that the optical effect is caused by non-crystal¬line potassium sulfate droplets. The droplets were characterized by use of XRD, SEM/EDX and Raman spectroscopy. The size range of the particles is in the order of 5-50 micrometers. It was found that the droplets consisted of potassium sulfate, even if other sulfate compounds were added to the glass. The amount of sulfate compound added, the melting temperature of the furnace and the melting time have significant effect on the optical density of the glass. The optical density of the glass can be correlated to the calculated surface tension of the host glass, suggesting that phase separation of a sulfate enriched liquid phase is part of the mecha¬nism forming the droplets. By adding pigments several different colours can be obtained, but the alabaster effect is not achieved during reducing conditions, thus it seems not possible to produce colours originating from reduced pigments. Pigments tested were Cr, Fe, Co, Cu, Au, Mo/Se, Nd and Ti/Ce/Se.
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| 2. |
- Grund Bäck, Lina, et al.
(författare)
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X-ray and UV–Vis-NIR absorption spectroscopy studies of the Cu (I) and Cu (II) coordination environments in mixed alkali-lime-silicate glasses
- 2019
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Ingår i: Journal of Non-Crystalline Solids: X. - : Elsevier. - 2590-1591. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The local structures of Cu(I) and Cu(II) in (20-x)Na2O-xK2O-10CaO-70SiO2 glasses with a copper content of 0.4 mol% have been investigated by Cu K-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES). Complementary data for Cu(II) was derived using UV–Vis-NIR spectroscopy. Indication for mainly linear two-fold coordination of the Cu+ ion was found by both EXAFS and XANES, but other coordination between Cu+ and O2– cannot be excluded. The Cu(I)-O bond lengths were found to be 1.79–1.83 ± 0.02 Å. EXAFS results showed that Cu(II) was mostly present in a Jahn-Teller distorted environment with oxygen, an octahedron with four shorter Cu(II)-O bonds and two longer in axial position. The equatorial bond lengths were found to be 1.89–1.91 ± 0.02 Å and the axial 2.20–2.24 ± 0.02 Å with no effect of the Jahn-Teller distortion of the octahedron when the glass composition was altered.
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| 3. |
- Houshmand, F., et al.
(författare)
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Exciton effect in new generation of carbon nanotubes : graphdiyne nanotubes
- 2020
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Ingår i: Journal of Molecular Modeling. - : Springer. - 1610-2940 .- 0948-5023. ; 26:7, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Graphdiyne-based nanotubes (GDNTs) are a novel type of carbon nanotubes. While conventional carbon nanotubes (CNTs) aregenerated by rolling graphene sheets, GDNTs are generated by rolling sheets that are similar to graphene but where the edges areelongated by the introduction of additional acetylene bonds between vertices (C6 aromatic rings). Such nanotubes are predicted tohave many useful practical applications, but a thorough understanding of the relationship between their structure and theirphysical properties is still missing. We present a theoretical study of the electronic and optical properties of GDNTs. Thestructural, electronic, and optical properties of GDNTs with different diameters (i.e., 2–10 additional acetylene bonds) havebeen studied systematically by using density function theory (DFT) and self-consistent charge density functional tight-binding(SCC-DFTB) and by solving the Bethe–Salpeter equation (BSE), with and without considering the electron-hole interactions.The results indicate that the GDNTs are semiconductors with the direct band gap in close range, which is beneficial forphotoelectronic devices and applications. Moreover, the absorption spectra of the GDNTs with different edge structures, (armchair,and zigzag) revealed little differences between the optical spectra of armchair and zigzag GDNTs, which could mean thatfine separation between those structures (a process that is likely difficult and expensive in practice) will not be necessary.Importantly, the nanotubes were highly stable based on their cohesive energies, and their exciton binding energies were as largeas about ~ 1 eV. From a methodological point of view, SCC-DFTB was found to be in agreement with more elaborate DFTcalculations for most systems.
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| 4. |
- Mahajan, Rashmi, et al.
(författare)
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Improved Solvothermal Synthesis of gamma-Fe2O3 Magnetic Nanoparticles for SiO2 Coating
- 2021
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Monodisperse magnetic gamma-Fe2O3 nanoparticles (MNPs) were prepared by a simple, improved, one-pot solvothermal synthesis using SDS and PEG 6000 as double capping reagents. This double protecting layer afforded better MNP uniformity (Z average 257 +/- 11.12 nm, PDI = 0.18) and colloidal stability. Materials were characterized by DLS, SEM, TEM, XPS, and XRD. The use of these MNPs in the synthesis of core-shell structures with uniform and tunable silica coatings was demonstrated, as silica coated MNPs are important for use in a range of applications, including magnetic separation and catalysis and as platforms for templated nanogel synthesis.
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| 5. |
- Suriyanarayanan, Subramanian, et al.
(författare)
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Highly Efficient Recovery and Recycling of Cobalt from Spent Lithium-Ion Batteries Using an N-Methylurea-Acetamide Nonionic Deep Eutectic Solvent
- 2023
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:7, s. 6959-6967
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Tidskriftsartikel (refereegranskat)abstract
- The growing demand for lithium-ion batteries (LiBs) for the electronic and automobile industries combined with the limited availability of key metal components, in particular cobalt, drives the need for efficient methods for the recovery and recycling of these materials from battery waste. Herein, we introduce a novel and efficient approach for the extraction of cobalt, and other metal components, from spent LiBs using a nonionic deep eutectic solvent (ni-DES) comprised of N-methylurea and acetamide under relatively mild conditions. Cobalt could be recovered from lithium cobalt oxide-based LiBs with an extraction efficiency of >97% and used to fabricate new batteries. The N-methylurea was found to act as both a solvent component and a reagent, the mechanism of which was elucidated.
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| 6. |
- Bring, Torun, et al.
(författare)
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Colour development in copper ruby alkali silicate glasses : Part 1. The impact of tin (II) oxide, time and temperature
- 2007
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Ingår i: Glass Technology, Eur J Glass Sci Technol A. - : Society of Glass Technology. ; 48:2, s. 101-108
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Tidskriftsartikel (refereegranskat)abstract
- The development of the red colour in copper ruby alkali silicate glasses has been studied by means of ultraviolet/visible spectroscopy, TEM and EXAFS. The results show that in both red and slightly overstruck, brownish glasses the colour is due to clusters of metallic copper. Before striking non-coloured glasses contain mainly cuprous ions, Cu+. Tin acts as a reducing agent but also has an accelerating effect on colour development.
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| 7. |
- Karlsson, Stefan, 1984-, et al.
(författare)
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Mechanical, thermal, and structural investigations of chemically strengthened Na2O-CaO-Al2O3-SiO2 glasses
- 2022
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Ingår i: Frontiers in Materials. - : Frontiers Media S.A.. - 2296-8016. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- For a series of conventional soda-lime-silicate glasses with increasing Al2O3 content, we investigated the thermal, mechanical, and structural properties before and after K+-for-Na+ ion-exchange strengthening by exposure to molten KNO3. The Al-for-Si replacement resulted in increased glass network polymerization and lowered compactness. The glass transition temperature (T (g)), hardness (H) and reduced elastic modulus (E (r)), of the pristine glasses enhanced monotonically for increasing Al2O3 content. H and E (r) increased linearly up to a glass composition with roughly equal stoichiometric amounts of Na2O and Al2O3 where a nonlinear dependence on Al2O3 was observed, whereas H and E (r) of the chemically strengthened (CS) glasses revealed a strictly linear dependence. T (g), on the other hand, showed linear increase with Al-for-Si for pristine glasses while for the CS glasses a linear to nonlinear trend was observed. Solid-state Al-27 nuclear magnetic resonance (NMR) revealed the sole presence of AlO4 groups in both the pristine and CS glasses. Na-23 NMR and wet-chemical analysis manifested that all Al-bearing glasses had a lower and near-constant K+-for-Na+ ion exchange ratio than the soda-lime-silicate glass. Differential thermal analysis of CS glasses revealed a "blurred " glass transition temperature (T (g)) and an exothermic step below T (g); the latter stems from the relaxation of residual compressive stresses. The nanoindentation-derived hardness at low loads and n(M O-(2))/n(Al2O3) & AP; 1 for the CS glasses, which is attributed to an increased elastic energy recovery that is linked to the glass compactness.
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| 8. |
- Wójcik, Natalia A., et al.
(författare)
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The influence of Be addition on the structure and thermal properties of alkali-silicate glasses
- 2019
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 521
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Tidskriftsartikel (refereegranskat)abstract
- Be-Na-(Li)-Si oxide glasses containing up to 15 mol% of BeO were prepared. Their structure was characterized by X-ray powder diffraction and Raman as well as infrared spectroscopic techniques, while their chemical compositions were examined by Inductively Coupled Plasma Optical Emission Spectrometry. All materials were found to be amorphous and contain Al contaminations from minor dissolution of the alumina crucibles. The results of Raman and IR spectroscopies showed that BeO addition to Na-(Li)-Si glass systems resulted in the formation of [BeO4/2](2-) tetrahedra which are inserted into the silicate glass network, demonstrating the intermediate glass-forming role of BeO. In parallel, the effective destruction of Si-O-Si bridges was observed by vibrational spectroscopy. The glass transition temperature was studied by Differential Thermal Analysis and found to range from about 431 degrees C to 551 degrees C. A significant increase in T-g by 70 degrees C was found as SiO2 was substituted by up to 15 mol% BeO.
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| 9. |
- Golker, Kerstin, et al.
(författare)
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Hydrogen bond diversity in the pre-polymerization stage contributes to morphology and MIP-template recognition - MAA versus MMA
- 2015
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 66, s. 558-568
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Tidskriftsartikel (refereegranskat)abstract
- This report demonstrates that the diversity of hydrogen bond interactions present in molecularly imprinted polymer pre-polymerization mixtures, typically associated with binding-site heterogeneity, can also contribute to morphological characteristics that may influence polymer-template recognition. Comparisons have been made between a series of bupivacaine molecularly imprinted methacrylic acid (MAA)-ethylene glycol dimethacrylate (EGDMA) copolymers and a series of analogous methyl methacrylate (MMA)-EGDMA copolymers using comprehensive molecular dynamics studies of the respective pre-polymerization mixtures, template-polymer binding studies and detailed BET surface area and BJH porosity analyses. The role of the carboxylic acid functionality of MAA, and in particular the acidic proton, in generating morphological features conducive to analyte access (slit-like rather than ink bottle-like structures) and recognition is discussed.
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| 10. |
- Suriyanarayanan, Subramanian, et al.
(författare)
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Sustainable synthesis of hierarchically grown chloramphenicol-imprinted poly(caffeic acid) nanostructured films
- 2023
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Ingår i: Journal of Applied Polymer Science. - : John Wiley & Sons. - 0021-8995 .- 1097-4628. ; 140:9
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Tidskriftsartikel (refereegranskat)abstract
- Hierarchically nanostructured chloramphenicol (CLP) imprinted thin polymer films have been developed using a renewable monomer, the antioxidant caffeic acid (CA), using sacrificial nanostructures to induce porosity into the films. The poly(caffeic acid) (PCA) films were synthesized on Au/quartz resonators via greener polymerization conditions (clean energy electropolymerization in aqueous buffer or a non-ionic deep eutectic solvent). The sacrificial nanostructures explored included zein-based protein nanobeads, anodized alumina membrane, and Tween 20-derived polysorbate micelles, where dissolution of the sacrificial nanostructure templates from the PCA films afforded uniform long-range hyperporous networks, nanowires and nanoparticles, respectively, as revealed by SEM studies. Selective extraction of the CLP template from PCA films, was monitored by XPS, and afforded CLP selective cavities. The CLP-imprinted PCA(zein) films demonstrated eight- to 25-fold higher sensitivity than the other nanostructures in a QCM-sensor format, the limit of detection (LOD) under optimized FIA conditions was 50 mM. Significant sensitivities for CLP in milk were observed (1.5 mu g/ml to 3 mg/ml), covering the clinically relevant concentration range. The PCA(zein) thin films selectively differentiate CLP from structurally related antibiotics and are robust. Their production from renewable feedstocks of biological origin highlights the potential of this class of nanostructured materials for applications utilizing thin films.
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