| 1. |
- McCoy, Thomas M, et al.
(författare)
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Spontaneous Self-Assembly of Thermoresponsive Vesicles Using a Zwitterionic and an Anionic Surfactant
- 2020
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 21:11, s. 4569-4576
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Tidskriftsartikel (refereegranskat)abstract
- Spontaneous formation of vesicles from the self-assembly of two specific surfactants, one zwitterionic (oleyl amidopropyl betaine, OAPB) and the other anionic (Aerosol-OT, AOT), is explored in water using small-angle scattering techniques. Two factors were found to be critical in the formation of vesicles: surfactant ratio, as AOT concentrations less than equimolar with OAPB result in cylindrical micelles or mixtures of micellar structures, and salt concentration, whereby increasing the amount of NaCl promotes vesicle formation by reducing headgroup repulsions. Small-angle neutron scattering measurements reveal that the vesicles are approximately 30-40 nm in diameter, depending on sample composition. Small-angle X-ray scattering measurements suggest preferential partitioning of OAPB molecules on the vesicle inner layer to support vesicular packing. Heating the vesicles to physiological temperature (37 °C) causes them to collapse into smaller ellipsoidal micelles (2-3 nm), with higher salt concentrations (≥10 mM) inhibiting this transition. These aggregates could serve as responsive carriers for loading or unloading of aqueous cargoes such as drugs and pharmaceuticals, with temperature changes serving as a simple release/uptake mechanism.
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| 2. |
- Sarneel, Judith M., et al.
(författare)
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Reading tea leaves worldwide: Decoupled drivers of initial litter decomposition mass-loss rate and stabilization
- 2024
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Ingår i: ECOLOGY LETTERS. - : John Wiley & Sons. - 1461-023X .- 1461-0248. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models.
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| 3. |
- Luo, Chen, et al.
(författare)
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Soil contamination caused by fly ash from coal-fired thermal power plants in India: Spatiotemporal distribution and elemental leaching potential
- 2024
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Ingår i: Applied Geochemistry. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0883-2927 .- 1872-9134. ; 170
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Tidskriftsartikel (refereegranskat)abstract
- On combustion, coal produces fly ash (FA) and spheroidal carbonaceous particles (SCP) at high temperatures. Airborne particles like FA and SCP can be transported over long distances by wind, leading to the pollution of air and water resources. Concern mainly arises from various toxic metals loosely bound to the surface of FA and SCP. Here, we trace the provenance of SCP in soil samples collected upwind and downwind from two coal-fired thermal power plants (TPP) in central Nagpur (Khaperkheda and Koradi) that have been operational for over four decades. The samples showed morphological similarities between SCPs from soil samples and FA collected from the Khaperkheda power plant. The SCP distribution shows a sharp increase in the soil profiles coinciding with the expansion of the power plants between 2010 and 2015. Backward trajectories of winds were calculated to ascertain whether the sampling locations downwind of the TPPs were potentially affected by FA emissions. The results from the back trajectories indicate that emissions from the TPP are directed toward the sampling sites. Finally, leaching experiments were conducted in FA to assess the release of elements. Leaching experiments at 30, 40, and 50 degrees C and at a given pH or extraction time did not show any notable differences in elemental concentrations of Al, As, Ca, Cr, Co, Cu, Fe, Mn, Mo, Se, Ni, Ti, V, and Zn. The concentration of different elements mobilized from FA was high at pH 3, with rapid leaching occurring within the first 30 min of the experiment. Hence, disposal, reclamation, and management of FA need to be regulated and monitored correctly to ensure the safety of its use.
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| 4. |
- Minu, A., et al.
(författare)
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Spatial variation of nutrients and primary productivity in the Rufiji Delta mangroves, Tanzania
- 2020
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Ingår i: African Journal of Marine Science. - : NATL INQUIRY SERVICES CENTRE PTY LTD. - 1814-232X .- 1814-2338. ; 42:2, s. 221-232
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Tidskriftsartikel (refereegranskat)abstract
- Determinations of spatial and temporal variations in organic matter and nutrient dynamics in water and sediments are crucial for understanding changes in aquatic bodies. In this study, we (i) determine the spatial dynamics of dissolved inorganic nutrients, during the transition from the dry to the rainy season, and (ii) provide future productivity predictions for the Rufiji Delta mangroves, Tanzania, based on the input of various nutrients. Water samples were collected from six locations, three times per year between April 2012 and January 2014, and analysed for dissolved nutrients, total organic and inorganic carbon, chlorophylla, chlorophyllband total carotenoids. The prediction of future net primary productivity in the Rufiji mangroves was undertaken using the software STELLA. The mean nutrient concentrations were of the order: nitrate > phosphate > ammonium > silica > dissolved organic carbon. The study revealed that high nutrient concentrations occurred in the northern part of the Rufiji Delta as a result of anthropogenic influence in the watershed. Modelling of nutrient inputs into the delta indicated enhanced primary productivity, which is expected to increase the vulnerability of water quality in the near future due to eutrophication.
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