| 1. |
- de Woul, Mattias, 1972-
(författare)
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Response of glaciers to climate change : Mass balance sensitivity, sea level rise and runoff
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this study is to enhance our understanding of the response of glaciers to climate change. Global sea level is affected by changes in glacier ice volume, and melt-water from glaciers is a principal water source in many regions. This study applies glacier mass balance modelling, with varying complexity and spatial resolution, ranging from individual glaciers to regional and global assessments of glacier mass losses. Glaciers located in maritime environments generally show considerably higher mass balance sensitivities than those in continental settings. On average, an assumed increase in annual precipitation of +10% tends to offset the effect of an annual temperature change of +1 K, by roughly 20%. Two case studies, at Storglaciären, Sweden, and Hofsjökull, Iceland, involve model results of future mass balance change and glacier melt induced changes in runoff. Applying a temperature and precipitation scenario for Iceland in 2050 results in increased total runoff from Hofsjökull by roughly one third, and results emphasize the role of the firn layer in delaying water flow through glaciers, yielding a redistribution of discharge within the year. Based on a global gridded data set of glacierized area, the sea level equivalent from all mountain glaciers and ice caps outside the ice sheets in Greenland and Antarctica during 1961–2004, caused by changes in temperature and precipitation, is estimated to be 0.58±0.34 mm a–1. The mountain glaciers and ice caps around Antarctica alone contribute almost 40% of the global estimate, and hence their contribution is considerably larger than previously assumed.
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| 2. |
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| 3. |
- Eden, Mattias, et al.
(författare)
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Al and O substitutions in BaS-phases, Ba2AlxSi12-xN16-xO2+x : A TEM, XRD and solid-state NMR study
- 2008
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Ingår i: Solid State Sciences. - : Elsevier BV. - 1293-2558 .- 1873-3085. ; 10:1, s. 50-60
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Tidskriftsartikel (refereegranskat)abstract
- In a series of Ba-based oxonitrido-silicate S-phases (Ba2AlxSi12-xN16-xO2+x) spanning a compositional range up to x approximate to 3, we examine the incorporation of Al and O by Si-29 and Al-27 magic-angle spinning (MAS) solid state nuclear magnetic resonance (NMR) and Al-27 triple-quantum MAS (3QMAS). The 3QMAS spectra reveal Al-27 signals from two distinct structural environments, assigned to AlN4 or AlN3O tetrahedra, respectively, and with their relative amounts depending on the S-phase substitution parameter x. Si-29 NMR show variable fractions of SiN4 and SiN3O environments. The NMR results accord overall with a structural substitution model for which O enters at one crystallographic position (occupied according to N4-xOx), in conjunction with a random Al for Si substitution at two distinct crystallographic positions. This leads to S-phase frameworks built from SiN4, SiN3O, AlN4 and AlN3O tetrahedra.
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| 4. |
- Ekman, Mattias, 1974-
(författare)
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Den globala rättviserörelsen i svenska medier : Hegemoniska formationer i relationen mellan journalistik och kapitalism
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The mobilisations against global summits towards the end of the last millennium, and the creation of the World Social Forum (WSF) in 2001, made an emerging global network of social movements visible. This thesis analyses media representations of the global justice movement, with the intention of exploring the relation between journalism and hegemonic formations in the capitalist system. The analysis includes representations of social mobilisations against global summits between 1999 and 2007, and the WSF between 2001 and 2007, in all Swedish daily newspapers. The analysis draws on theories of journalism as a social institution, and Gramsci’s concept of hegemonic formations.Using critical discourse analysis (CDA), the dissertation reveals that the representation of protests subordinates political aspects to violence, and that discursive violence presupposes physical violence. The protests are generally defined from of a hegemonic position of the political, but sometimes protest emerges in relation to legitimate political departure points. Simultaneously it is also downplayed as anti-political. The representation of WSF is more heterogeneous. It is portrayed as: an alternative, an anti-movement, and a carnival. Some aspects of violence are also highlighted through the presence of absent violence. The representations both reproduce a hegemonic order, and in some cases highlight hegemonic struggle.The thesis concludes that the global justice movement actualizes relations between dominance and resistance in the global system, but that the distance between the social mobilization and the Swedish context, transforms the protests and the WSF to temporary and partly isolated events. The historical continuity in the relations between social mobilization and news journalism shows that social movements cannot rely upon conventional news coverage.
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| 5. |
- Gunawidjaja, Philips N., et al.
(författare)
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Quantifying apatite formation and cation leaching from mesoporous bioactive glasses in vitro : a SEM, solid-state NMR and powder XRD study
- 2012
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 22:15, s. 7214-7223
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Tidskriftsartikel (refereegranskat)abstract
- By employing solid-state nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy coupled with energy-dispersive X-ray (EDX) spectroscopy, we compare the biomimetic growth of calcium hydroxyapatite (HA) from an ordered mesoporous bioactive glass (MBG) in simulated body fluid (SBF) and buffered water solutions. For the latter medium, we also examine the effects of using two different MBG concentrations. We evaluate the predicting powers of PXRD and P-31 NMR for directly quantifying the relative amounts of biomimetic amorphous calcium phosphate (ACP) and HA: we observe a very good agreement between the two analytical techniques. Thanks to their mesoporous channel system, fluids readily penetrate throughout sub-mm sized MBG grains, as evidenced by EDX. The latter revealed distinct element-mappings across the material after its exposure to SBF compared to water. Under our in vitro conditions involving relatively high MBG-loadings in the solutions, the HA formation reduces in SBF relative to buffered water, particularly for increasing MBG concentration. These features stem from a high [Ca2+]/[PO43-] ratio resulting in the fluid medium, which retards the HA crystallization by inducing a rapid ACP precipitation and an accompanying depletion of phosphate ions in the solution. This has bearings on the design of bioactivity comparisons of bioglasses exhibiting significantly different cation compositions.
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| 6. |
- Kvedaraite, Egle, et al.
(författare)
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Intestinal stroma guides monocyte differentiation to macrophages through GM-CSF
- 2024
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Stromal cells support epithelial cell and immune cell homeostasis and play an important role in inflammatory bowel disease (IBD) pathogenesis. Here, we quantify the stromal response to inflammation in pediatric IBD and reveal subset-specific inflammatory responses across colon segments and intestinal layers. Using data from a murine dynamic gut injury model and human ex vivo transcriptomic, protein and spatial analyses, we report that PDGFRA+CD142−/low fibroblasts and monocytes/macrophages co-localize in the intestine. In primary human fibroblast-monocyte co-cultures, intestinal PDGFRA+CD142−/low fibroblasts foster monocyte transition to CCR2+CD206+ macrophages through granulocyte-macrophage colony-stimulating factor (GM-CSF). Monocyte-derived CCR2+CD206+ cells from co-cultures have a phenotype similar to intestinal CCR2+CD206+ macrophages from newly diagnosed pediatric IBD patients, with high levels of PD-L1 and low levels of GM-CSF receptor. The study describes subset-specific changes in stromal responses to inflammation and suggests that the intestinal stroma guides intestinal macrophage differentiation.
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| 7. |
- Leonova, Ekaterina, et al.
(författare)
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Nitrogenrich La-Si-Al-O-N oxynitride glass structures probed by solid state NMR
- 2008
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 354:1, s. 49-60
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the local structures of oxynitride La–Si–(Al)–O–N glasses by 29Si and 27Al magic-angle spinning (MAS) solid state Nuclear Magnetic Resonance (NMR). The glasses studied span an unprecedented range of compositions, up to >50 at.% lanthanum and nitrogen out of the cations and anions, respectively, and achievable through a recently introduced glass preparation route. Transmission as well as scanning electron microscopy verified homogeneous samples over length-scales down to 20 nm. As the nitrogen content of the glasses increased, 29Si NMR evidenced a progressive formation of Si–N bonds, with SiO2N2 tetrahedra dominating in the nitrogen-rich glass networks. In the oxygen-rich end of the series, aluminum is predominantly present in tetrahedral coordination as AlO4, whereas the glasses with highest nitrogen contents have a major fraction of AlO3N structural units. Trends in isotropic 29Si and 27Al chemical shifts and 27Al quadrupolar couplings are compared with results of La–Si–Al–O glasses and are discussed in relation to the glass compositions and their proposed structures.
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| 8. |
- Mathew, Renny, et al.
(författare)
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Solid-State (31)P and (1)H NMR Investigations of Amorphous and Crystalline Calcium Phosphates Grown Biomimetically From a Mesoporous Bioactive Glass
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:42, s. 20572-20582
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Tidskriftsartikel (refereegranskat)abstract
- By exploiting (1)H and (31)P magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, we explore the proton and orthophosphate environments in biomimetic amorphous calcium phosphate (ACP) and hydroxyapatite (HA), as grown in vitro at the surface of a 10CaO-85SiO(2)-5P(2)O(5) mesoporous bioactive glass (MBG) in either a simulated body fluid or buffered water. Transmission electron microscopy confirmed the presence of a calcium phosphate layer comprising nanocrystalline HA Two-dimensional (1)H-(31)P heteronudear correlation NMR established predominantly (1)H(2)O <->(31)PO(4)(3-) and O(1)H <->(31)PO(4)(3-) contacts in the amorphous and crystalline component, respectively, of the MBG surface-layer; these two pairs exhibit distinctly different (1)H <->(31)P cross-polarization dynamics, revealing a twice as large squared effective (1)H-(31)P dipolar coupling constant in ACP compared with HA. These respective observations are mirrored in synthetic (well-crystalline) HA, and the amorphous calcium orthophosphate (CaP) clusters that are present in the pristine MBG pore walls: besides highlighting very similar local (1)H and (31)P environments in synthetic and biomimetic HA, our findings evidence closely related NMR characteristics, and thereby similar local structures, of the CaP clusters in the pristine MBG relative to biomimetic ACP.
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| 9. |
- Pahari, Bholanath, et al.
(författare)
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Composition-property-structure correlations of scandium aluminosilicate glasses revealed by multinuclear 45Sc, 27Al and 29Si solid-state NMR
- 2012
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Ingår i: Journal of The American Ceramic Society. - : Wiley. - 0002-7820 .- 1551-2916. ; 95:8, s. 2545-1553
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Tidskriftsartikel (refereegranskat)abstract
- Many features of aluminosilicate glasses incorporating a rare-earth (RE) ion are dictated by its mass and cation field strength (CFS). ScAlSiO glasses are interesting because Sc3+ exhibits the highest CFS but the lowest mass of all RE3+ ions. We explore relationships between the glass composition and several physical properties, such as density, glass-transition temperature (Tg), Vickers hardness, and refractive index, over the glass forming region of the ternary Sc2O3Al2O3SiO2 system. The glasses exhibit uniform and unexpectedly low Tg-values (similar to 875 degrees C), but a high microhardness (approximate to 9.3 GPa) that correlates with the Sc2O3 content. 29Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy shows enhanced deshielding and a minor glass-network ordering as either the Al or Sc content of the glass increases. 27Al MAS NMR reveals that besides the expected AlO4 tetrahedra, substantial amounts of AlO5 (31%35%) and AlO6 (approximate to 5%) polyhedra are present in all ScAlSiO glass structures. 45Sc isotropic chemical shifts (similar to 92 ppm) derived from MAS and 3QMAS (triple-quantum MAS) NMR experiments are consistent with ScO6 environments.
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| 10. |
- Ren, Tie-zhen, et al.
(författare)
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SU-57 – An aluminosilicogermanate with a DFT topology and variable compositions
- 2009
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 117:1-2, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- An aluminosilicogermanate with a DFT zeotype framework (denoted as SU-57) was synthesized for the first time by ethanol-assisted hydrothermal synthesis at 160 and 170 °C. The compound was characterized by single crystal and powder X-ray diffraction, scanning and transmission electron microscopy, energy dispersive spectroscopy (EDS), thermogravimetry (TG) and solid state nuclear magnetic resonance (NMR) spectroscopy. SU-57 crystallizes in space group P42/n with estimated a ≈ 10.38–10.46 Å, c ≈ 8.88–8.91 Å, V ≈ 957–975 Å3. It has variable Al–Si–Ge composition with an approximate formula |C2H10N2| [Al(SixGe1−x)O4]2 (x ≈ 0.3–0.9), which results in a super-structure originated from different cation occupancies of the two unique tetrahedral (T) sites. Single crystal X-ray structure refinements, together with results from X-ray powder diffraction (XRPD) and EDS analysis, showed that (i) the AlO4 and (Si, Ge)O4 tetrahedra are only partially ordered over the DFT framework and do not follow a strict alternating manner. (ii) Al resides predominantly on one T site and Si and Ge predominantly on the other. (iii) The Al cation concentration (Al/(Al + Si + Ge)) is nearly constant and slightly less than 50 at%, while the Si and Ge cation concentrations vary over a large range. (iv) Al and Ge occupy both T sites. The cation disorder was confirmed by 27Al and 29Si solid state NMR. TG analysis and in situ XRPD showed that SU-57 was stable up to 375 °C in N2 atmosphere.
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