| 1. |
- An, Siwen, et al.
(författare)
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Signal-to-Noise Ratio Optimization in X-ray Fluorescence Spectrometry for Chromium Contamination Analysis
- 2021
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 230
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Tidskriftsartikel (refereegranskat)abstract
- In most cases, direct X-ray fluorescence (XRF) analysis of solutions entails technical difficulties due to a high X-ray scattering background resulting in a spectrum with a poor signal-to-noise ratio (SNR). Key factors that determine the sensitivity of the method are the energy resolution of the detector and the amount of scattered radiation in the energy range of interest. Limiting the width of the primary spectrum by the use of secondary targets, or filters, can greatly improve the sensitivity for specific portions of the spectrum. This paper demonstrates a potential method for SNR optimization in direct XRF analysis of chromium (Cr) contamination. The suggested method requires minimal sample preparation and achieves higher sensitivity compared to existing direct XRF analysis. Two states of samples, fly ash and leachate from municipal solid waste incineration, were investigated. The effects of filter material, its absorption edge and filter thickness were analyzed using the combination of Monte Carlo N-Particle (MCNP) code and energy-dispersive XRF spectrometry. The applied filter removes primary photons with energies interfering with fluorescence photons from the element of interest, thus results in lower background scattering in the spectrum. The SNR of Cr peak increases with filter thickness and reaches a saturation value when further increased thickness only increases the measurement time. Measurements and simulations show that a Cu filter with a thickness between 100 μm and 140 μm is optimal for detecting Cr by taking into account both the SNR and the exposure time. With direct XRF analysis for solutions, the limit of quantitation (LOQ) of the achieved system was 0.32 mg/L for Cr, which is well below the allowed standard limitation for landfills in Sweden. This work shows that XRF can gain enough sensitivity for direct monitoring to certify that the Cr content in leachate is below environmental limits.
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| 2. |
- Bautista-Puig, Núria, Postdoc Researcher, 1987-, et al.
(författare)
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Developing a sustainability implementation framework: insights from academic research on tools, initiatives and approaches
- 2023
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Ingår i: Environment, Development and Sustainability. - : Springer. - 1387-585X .- 1573-2975. ; , s. 11011-11031
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Tidskriftsartikel (refereegranskat)abstract
- Sustainability has been proposed to address societal challenges. A number of efforts have been undertaken to implement sustainability, particularly through frameworks such as tools, initiatives and approaches (TIAs). Most of the research on the implementation efforts has been in the corporate context. This paper is aimed at analysing the implementation of TIAs in academic research. A bibliometric analysis of twenty TIAs during the period 1961–2020 was carried out to analyse their implementation in academic research. The results highlight that there has been research published on all the TIAs analysed. The TIAs have a better balance and interrelations between the sustainability dimensions in their implementation than in the theory. The results show that for a better implementation of TIAs in academic research it is necessary to address sustainability dimensions (economic, environmental, social, and time) in a holistic and balanced way considering alignment of general and specific efforts, i.e. TIAs, and congruence (linking ‘theory’ and ‘implementation’). The results were integrated to propose a ‘Sustainability Implementation Framework’ (SIF), which is divided into three levels (i.e., Initiatives, Approaches, and Tools). The TIAs implementation should follow more strictly the definitions, or, perhaps, the TIAs definitions should be redefined to encompass the insights from their implementation.
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| 3. |
- Norberg, Peter, 1955-, et al.
(författare)
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En metod för framställning av agglomerat av utfällt silikamaterial, ett mikroporöst material innefattande sådan agglomerat och användning därav
- 2007
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Patent (populärvet., debatt m.m.)abstract
- Föreliggande uppfinning avser en metod att producera ett material som innefattar agglomererade partiklar av utfälld kiseldioxid, innefattande framställning av en lösning av åtminstone ett metallsalt (M), där metalljonen/-jonerna är tvåvärd(a) eller flervärd(a). En lösning av alkalimetall (M) silikat med ett molförhållande SiO2/M2O om 0.5 - 100 framställs. Lösningarna blandas och blandningen omrörs, och ett koagel tillåts bildas. Koaglet uppsamlas och behandlas för att tillhandahålla ett material som har en torrsubstans om >15, företrädesvis >97%. Ett material som kan erhållas med processen tillhandahålles också.
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| 4. |
- Twumasi, Ebenezer, 1980-, et al.
(författare)
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Tailored Precipitated Silica Adsorbents for the Built Environment
- 2011
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Ingår i: XII DBMC: 12th International Conference on Durability of Building Materials and Components (Vol. 4). - Porto : FEUP Edições. - 9789727521326
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Konferensbidrag (refereegranskat)abstract
- The paper provides a review of the synthesis and adsorptive properties of a novel class of precipitated silica materials. To enhance or tailor the adsorption efficiency, various trapping chemicals (potassium hydroxide, potassium permanganate) or co-adsorbents (coconut activated carbon) are incorporated in the structure of the substrate material. Further, it discusses the applicability and performance over time of the material as adsorbents for removal of hydrogen sulphide, sulphur dioxide and toluene contaminants which are potentially hazardous to sensitive equipment and more importantly, human health. Chemical substances in the air are an unavoidable by-product of most human endeavours within industry and transportation. The need for adsorbents to combat Airborne Molecular Contamination (AMC) follows from the continued intensification of the global environmental movement as well as the rapid industrialisation of developing countries. The removal performance of modified precipitated silica adsorbent shows that the new adsorbent can be tailored to remove low concentrations of sulphur dioxide, hydrogen sulphide and toluene contaminants at indoor environment conditions. The results further shows that the new precipitated silica adsorbent impregnated with 8 wt% KOH shows better performance than commercial alumina impregnated with 8 wt% KMnO4.The adsorbent material may find interesting and efficient uses as passive sinks for pollutants incorporated into more traditional building products such as acoustic baffles or as ingredients in various coatings. The filter material is environmentally friendly and consists of benign chemicals that are abundant worldwide. Performance over time aspects, re-use and recycling of exhausted filter materials are key issues addressed.
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| 5. |
- Liu, Zhina, et al.
(författare)
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Kinematics and 3-D internal deformation of granular slopes : analogue models and natural landslides
- 2013
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Ingår i: Journal of Structural Geology. - : Elsevier BV. - 0191-8141 .- 1873-1201. ; 53, s. 27-42
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Tidskriftsartikel (refereegranskat)abstract
- This study uses results from a series of analogue models, and field observations, scanned data and sections of natural landslides to investigate the kinematics and internal deformation during the failure of an unstable slope. The models simulate collapse of granular slopes and focus on the spatial and temporal distribution of their internal structures. Using a series of systematically designed models, we have studied the effect of friction and deformability of the runout base on internal deformation within a granular slope. The results of these different models show that the collapse of granular slopes resulted in different-generation extensional faults at the back of the slope, and contractional structures (overturned folds, sheath folds and thrusts) at the toe of the slope. The failure surfaces and the volume of the failure mass changed both spatially and temporally. Younger failure surfaces formed in the back of the older ones by incorporating additional new material from the head of the slope. Our model results also show that the nature of the runout base has a significant influence on the runout distance, topography and internal deformation of a granular slope. Model results are compared with natural landslides where local profiles were dug in order to decipher the internal structures of the failure mass. The natural cases show similar structural distribution at the head and toe of the failure mass. As in model results, our field observations indicate the presence of at least two generations of failure surfaces where the older ones are steeper.
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| 6. |
- Nilfouroushan, Faramarz, et al.
(författare)
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Sensitivity analysis of numerical scaled models of fold-and-thrust belts to granular material cohesion variation and comparison with analogue experiments
- 2012
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Ingår i: Tectonophysics. - : Elsevier. - 0040-1951 .- 1879-3266. ; 526-529, s. 196-206
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Tidskriftsartikel (refereegranskat)abstract
- Scaled analog and numerical brittle–viscous shortening models are employed to evaluate how fold–thrust structures evolve with changes in the cohesion of brittle materials, a rather poorly constrained physical parameter at this scale of experiment. The shortening models are characterized by various styles of shear zones and features resembling pop-up structures. The kinematics, geometry, and number of these structures are controlled by the viscous detachment layers in the models; the finite deformation of the model wedges is fundamentally different in model sets with one or two viscous layers. We demonstrate that the structural evolution of the numerical models is very sensitive to small changes in cohesion value. This is especially pronounced in the experiments that incorporate two weak viscous layers. The overall deformation of the numerical models is most similar to analog models when cohesion values are 70–80 Pa.
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| 7. |
- Nilfouroushan, Faramarz, et al.
(författare)
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Thermal-mechanical modeling of salt-based mountain belts with pre-existing basement faults: application to the Zagros fold and thrust belt, southwest Iran
- 2013
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Ingår i: Tectonics. - : American Geophysical Union (AGU). - 0278-7407 .- 1944-9194. ; 32:5, s. 1212-1226
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional thermal-mechanical models of thick-skinned, salt-based fold and thrust belts, such as the Zagros, SW Iran, are used to address: 1) the degree of deformation and decoupling between cover and basement rocks due to the presence of a weak salt detachment; 2) the reactivation potential of pre-existing basement normal faults due to brittle or ductile behavior of the lower crust (as related to cold or hot geothermal gradients); and 3) variations in deformation style and strain distribution. The geometry and kinematics of the orogenic wedge and the activity of pre-existing basement faults are strongly influenced by the geothermal gradient (defined by the Moho temperature, MT) and basement rheology. We infer that the MT plays a major role in how the lower and upper crust transfer deformation towards the foreland. In relatively hot geotherm models (MT = 600°C at 36 km depth), the lowermost basement deforms in a ductile fashion while the uppermost basement underlying the sedimentary cover deforms by folding, thrusting, and displacements along pre-existing basement faults. In these models, cover units above the salt detachment occur within a less deformed, wide plateau in the hinterland. In relatively cold geotherm models (MT = 400°C at 36 km depth), deformation is mainly restricted to basement imbricate thrusts that form within the orogenic hinterland. Detachment folding, thrusting and gravity gliding occur within cover sediments above uplifted basement blocks. Gravity gliding contributes to a larger amount of shortening in the cover compared to the basement.
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| 8. |
- Sorbi, Mohammad Reza, et al.
(författare)
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Seismicity patterns associated with the September 10th, 2008 Qeshm earthquake, South Iran
- 2012
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Ingår i: International journal of earth sciences. - : Springer Science and Business Media LLC. - 1437-3254 .- 1437-3262. ; 101:8, s. 2215-2223
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Tidskriftsartikel (refereegranskat)abstract
- The b value of the Gutenberg-Richter relation and the standard deviate, Z, were calculated to investigate the temporal and spatial variations in seismicity patterns associated with the September 10th, 2008 (Mw=6.1) Qeshm earthquake. The temporal variations of b value illustrate a distinct dramatic drop preceding the Qeshm earthquake and the spatial changes in b value highlight a zone with an abnormally low b value around the epicenter of this event. The Cumulative number and Z value as a function of time shows a precursory seismic quiescence preceding the 2008 Qeshm earthquake that observed for one year in a circle with R=50 km around its epicenter. The spatial distribution map of the standard deviate, Z, also exhibits an obvious precursory seismic quiescence region before the 2008 Qeshm event around the epicenter of this event. Interestingly, the precursory seismic quiescence region is approximately consistent with low b value anomaly region and both have E-W to NE-SW trend. These two precursory anomalies took place in relatively large regions, which were possibly relevant to the preparation zone of the 2008 Qeshm event.
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| 9. |
- Farzipour-Saein, Ali, et al.
(författare)
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The effect of basement step/topography on the geometry of the Zagros fold and thrust belt (SW Iran) : an analogue modeling approach
- 2013
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Ingår i: International journal of earth sciences. - : Springer Science and Business Media LLC. - 1437-3254 .- 1437-3262. ; 102:8, s. 2117-2135
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Tidskriftsartikel (refereegranskat)abstract
- Systematic analogue models are run to study the variation in deformation across basement steps in the Zagros Fold-Thrust Belt. Our model results demonstrate that basement configuration/topography influences the sedimentation thickness and, hence, the kinematics and geometric evolution of the fold and thrust belt. The greater the difference in thickness between the adjacent cover units across a basement step, the sharper and clearer will be the offset the deformation front. Based on model results, we conclude that in a fold-thrust belt, where basement step/topography is covered by a layer of ductile salt acting as a decollement, the effect of the salt decollement on the evolution of the belt is far greater than the effect of thickness variation of the cover units.
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| 10. |
- Mousavi, Z., et al.
(författare)
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Global Positioning System constraints on the active tectonics of NE Iran and the South Caspian region
- 2013
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Ingår i: Earth and Planetary Science Letters. - : Elsevier. - 0012-821X .- 1385-013X. ; 377-378, s. 287-298
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Tidskriftsartikel (refereegranskat)abstract
- We present a velocity field compiled from a network of 27 permanent and 20 campaign GPS stations across NE Iran. This new GPS velocity field helps to investigate how Arabia-Eurasia collision deformation is accommodated at the northern boundary of the deforming zone. The present-day northward motion decreases eastward from 11 mm/yr at Tehran (~52°E) to 1.5 mm/yr at Mashhad (~60°E). N-S shortening across the Kopeh Dagh, Binalud and Kuh-e-Surkh ranges sums to 4.5±0.5 mm/yr at longitude 59°E. The available GPS velocities allow us to describe the rigid-body rotation of the South Caspian about an Euler pole that is located further away than previously thought. We suggest that two new stations (MAVT and MAR2), which are sited far from the block boundaries, are most likely to indicate the full motion of the South Caspian basin. These stations suggest that NW motion is accommodated by right-lateral slip on the Ashkabad fault (at a rate of up to 7 mm/yr) and by up to 4-6 mm/yr of summed left-lateral slip across the Shahroud left-lateral strike-slip system. Our new GPS results are important for assessing seismic hazard in NE Iran, which contains numerous large population centers and possesses an abundant historical earthquake record. Our results suggest that the fault zones along the eastern Alborz and western Kopeh Dagh may accommodate slip at much faster rates than previously thought. Fully assessing the role of these faults, and the hazard that they represent, requires independent verification of their slip-rates through additional GPS measurements and geological fieldwork.
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