| 41. |
- Pourrahimi, Amir Masoud, et al.
(författare)
-
Aqueous synthesis of (21̅0) oxygen terminated defect free hierarchical ZnO particles and their heat treatment for enhanced reactivity
- 2016
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32:42, s. 11002-11013
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Tidskriftsartikel (refereegranskat)abstract
- A controlled aqueous growth of 1 µm flower-shaped ZnO particles with a hierarchical subset of exposed nano-sheets represented by {21̅0} crystal faces, followed by annealing at temperatures up to 1000 °C, is presented. The flower-shaped particles showed superior photocatalytic performance compared to the crystal faces of 20 nm ZnO nanoparticles. The photocatalytic reaction rate of the flower-shaped particles before annealing was 2.4 times higher per m2 compared with that of the nanoparticles with double specific surface area. Crystal surface defects and nano-sized pores within the flower-shaped particles were revealed by porosity measurement and electron microscopy. A heat treatment at 400 °C was found to be optimal for removal of nanoporosity/surface defects and impurities while retaining the hierarchical superstructure. The heat treatment resulted in a photo-degradation efficiency that increased by an additional 43 %, although the specific surface area decreased from 16.7 to 13.0 m2g-1. The enhanced photocatalytic effect remained intact under both acidic and alkaline environments owing to the {21̅0} crystal surfaces, which were less prone to dissolution than the nanoparticles. The photocatalytic performance relied on primarily three factors: the removal of surface impurities, the oxygen termination of the {21̅0} crystal faces, and the promotion of charge carrier lifetime by removal of lattice defects acting as recombination centres. The synthesis presented is an entirely hydrocarbon- and surfactant free ('green') preparation scheme, and the formation of the flower-shaped particles was favored solely by optimization of the reaction temperature after the correct nitrate salts precursor concentrations had been established.
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| 42. |
- Pourrahimi, Amir Masoud, 1985, et al.
(författare)
-
Making an ultralow platinum content bimetallic catalyst on carbon fibres for electro-oxidation of ammonia in wastewater
- 2019
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Ingår i: Sustainable Energy and Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 3:8, s. 2111-2124
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Tidskriftsartikel (refereegranskat)abstract
- Electrocatalysis of wastewater containing ammonia is a promising alternative to chemical and biological water purification for several reasons, one being that energy-rich hydrogen gas is generated as a by-product while the reaction can be strictly controlled to meet demands. An objective has been to reduce the loading of expensive platinum (Pt) in the catalyst electrodes, and to reduce the poisoning of the metal surface during the electrolysis. Herein, the co-deposition of a copper-platinum (Cu-Pt) bimetallic alloy onto carbon filaments, stripped from their polymeric coating, is shown to give an electrocatalytic performance superior to that of pure Pt at a content of less than 3 wt% Pt. The key to the enhanced performance was to take advantage of micrometer-sized carbon filaments to distribute a very large bimetallic alloy surface uniformly over the filaments. The Cu-Pt-alloy-coated filaments also suffer less electrode poisoning than pure Pt, and are bonded more strongly to the carbon fibre due to better mechanical interlocking between the bimetallic alloy and the carbon filaments. High-resolution electron microscopy studies combined with a tuned electro-deposition process made it possible to tailor the catalyst micro/nano morphology to reach a uniform coverage, surrounding the entire carbon filaments. The results are promising steps towards large-scale wastewater treatment, combined with clean energy production from regenerated hydrogen.
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| 43. |
- Pourrahimi, Amir Masoud, et al.
(författare)
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Water-based synthesis and cleaning methods for high purity ZnO nanoparticles - comparing acetate, chloride, sulphate and nitrate zinc salt precursors
- 2014
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:67, s. 35568-35577
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Tidskriftsartikel (refereegranskat)abstract
- A low temperature (60 degrees C) aqueous synthesis method of high purity ZnO nanoparticles intended as fillers for ultra-low electrical conductivity insulations is described. Particles were prepared under identical conditions from different zinc salts based on nitrate, chloride, sulphate or acetate to compare their abilities to form high yields of sub-50 nm particles with narrow size distribution. The acetate salt gave uniform 25 nm ZnO particles with a conical prism shape. The chloride and sulphate derived particles showed mixed morphologies of nanoprisms and submicron petals, whereas the nitrate salt yielded prisms assembled into well-defined flower shapes with spiky edges. The micron-sized flower shapes were confirmed by Xray diffraction to consist of the smaller prism units. Photoluminescence spectroscopy showed emission in the blue-violet region with little variation depending on precursor salt, suggesting that the spectra were dependent on the primary nanoprism formation and rather independent of the final particle morphology. Microscopy revealed that the salt residuals after the reaction showed different affinity to the particle surfaces depending on the type of salt used, with the acetate creating ca. 20 nm thick hydrated shells; and in falling order of affinity: chloride, sulphate and nitrate. An acetate ion shielding effect during the synthesis was therefore assumed, preventing nanoparticle fusion during growth. Varying the concentrations of the counter-ions confirmed the shielding and only the acetate anions showed an ability to stabilize solitary nanoprisms formation in reaction yields from 2 to 10 g L-1. Ultrasonic particle surface cleaning was significantly more efficient than water replacement, resulting in a stable aqueous dispersion with a high zeta potential of 38.9 mV at pH 8.
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| 44. |
- Sampson, Joshua N., et al.
(författare)
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Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for 13 Cancer Types
- 2015
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 107:12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, h(l)(2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (rho = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (rho = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (rho = 0.51, SE = 0.18), and bladder and lung (rho = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.
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| 45. |
- Spikol, Daniel
(creator_code:cre_t, creator_code:res_t)
-
Forskarnas galleri #5 : People have the power: IOTAP on exhibit
- 2018
-
Konstnärligt arbeteabstract
- Överallt samlar sensorer data som analyseras för att räkna ut hur man sparar energi, hur mycket insulin som ska injiceras, var den närmaste hyrbilen finns, hur många människor som fortfarande är kvar inne i en brinnande byggnad... Denna snabba spridning av teknik kallas för Sakernas Internet, eller IoT. Människor har makten, eller har vi verkligen det? Hur mycket värderar vi vår integritet? Vilka internetanslutna gadgets hjälper oss att leva ett hälsosamt och hållbart liv - och vilka prylar kommer bara att öka vår stressnivå? När blir användningen missbruk? Utställningen undersöker hur IoT påverkar människor, samhälle och industri. Forskningsprojekt i utställningen: Emergent Configuration for IoT Systems (ECOS+), Smart energy management and security (SEMS), Fair Data, Walk the ward, Dynamic Intelligent Sensor-Intensive Systems (DISS), PELARS-projektet och Busrunner presenteras i "IOTAP-labbet"
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| 46. |
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| 47. |
- Strain, I. N., et al.
(författare)
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Electrospinning of recycled PET to generate tough mesomorphic fibre membranes for smoke filtration
- 2015
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 3:4, s. 1632-1640
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Tidskriftsartikel (refereegranskat)abstract
- Tough fibrous membranes for smoke filtration have been developed from recycled polyethylene terephthalate (PET) bottles by solution electrospinning. The fibre thicknesses were controlled from 0.4 to 4.3 mu m by adjustment of the spinning conditions. The highest fibre strength and toughness were obtained for fibres with an average diameter of 1.0 mu m, 62.5 MPa and 65.8 MJ m(-3), respectively. The X-ray diffraction (XRD) patterns of the fibres showed a skewed amorphous halo, whereas the differential scanning calorimetry (DSC) results revealed an apparent crystallinity of 6-8% for the 0.4 and 1 mu m fibres and 0.2% crystallinity for the 4.3 mu m fibres. Heat shrinkage experiments were conducted by exposing the fibres to a temperature above their glass transition temperature (T-g). The test revealed a remarkable capability of the thinnest fibres to shrink by 50%, which was in contrast to the 4.3 mu m fibres, which displayed only 4% shrinkage. These thinner fibres aka showed a significantly higher glass transition temperature (+15 degrees C) than that of the 4.3 mu m fibres. The results suggested an internal morphology with a high degree of molecular orientation in the amorphous segments along the thinner fibres, consistent with a constrained mesomorphic phase formed during their rapid solidification in the electric field. Air filtration was demonstrated with cigarette smoke as a model substance passed through the fibre mats. The 0.4 mu m fibres showed the most effective smoke filtration and a capacity to absorb 43x its own weight in smoke residuals. whereas the 1 mu m fibres showed the best combination of filtration capacity (32x) and mechanical robustness. The use of recycled PET in the form of nanofibres is a novel way of turning waste into higher-value products.
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| 48. |
- Wu, Qiong, et al.
(författare)
-
Conductive biofoams of wheat gluten containing carbon nanotubes, carbon black or reduced graphene oxide
- 2017
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 7:30, s. 18260-18269
-
Tidskriftsartikel (refereegranskat)abstract
- Conductive biofoams made from glycerol-plasticized wheat gluten (WGG) are presented as a potential substitute in electrical applications for conductive polymer foams from crude oil. The soft plasticised foams were prepared by conventional freeze-drying of wheat gluten suspensions with carbon nanotubes (CNTs), carbon black (CB) or reduced graphene oxide (rGO) as the conductive filler phase. The change in conductivity upon compression was documented and the results show not only that the CNT-filled foams show a conductivity two orders of magnitude higher than foams filled with the CB particles, but also that there is a significantly lower percolation threshold with percolation occurring already at 0.18 vol%. The rGO-filled foams gave a conductivity inferior to that obtained with the CNTs or CB particles, which is explained as being related to the sheet-like morphology of the rGO flakes. An increasing amount of conductive filler resulted in smaller pore sizes for both CNTs and CB particles due to their interference with the ice crystal formation before the lyophilization process. The conductive WGG foams with CNTs were fully elastic with up to 10% compressive strain, but with increasing compression up to 50% strain the recovery gradually decreased. The data show that the conductivity strongly depends on the type as well as the concentration of the conductive filler, and the conductivity data with different compressions applied to these biofoams are presented for the first time.
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| 49. |
- Wu, Qiong, et al.
(författare)
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Highly porous flame-retardant and sustainable biofoams based on wheat gluten and in situ polymerized silica
- 2014
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 2:48, s. 20996-21009
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a novel type of flame-retardant biohybrid foam with good insulation properties based on wheat gluten and silica, the latter polymerized in situ from hydrolysed tetraethyl orthosilicate (TEOS). This led to the formation of intimately mixed wheat gluten and silica phases, where, according to protein solubility measurements and infrared spectroscopy, the presence of silica had prohibited full aggregation of the proteins. The foams with "built-in" flame-retardant properties had thermal insulation properties similar to those of common petroleum- and mineral-based insulation materials. The foams, with a porosity of 87 to 91%, were obtained by freeze-drying the liquid mixture. Their internal structure consisted of mainly open cells between 2 and 144 mu m in diameter depending on the foam formulation, as revealed by mercury intrusion porosimetry and scanning electron microscopy. The foams prepared with >= 30% TEOS showed excellent fire-retardant properties and fulfilled the criteria of the best class according to UL94 fire testing standard. With increasing silica content, the foams became more brittle, which was prevented by cross-linking the materials (using gluteraldehyde) in combination with a vacuum treatment to remove the largest air bubbles. X-ray photoelectron and infrared spectroscopy showed that silicon was present mainly as SiO2 .
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| 50. |
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