| 1. |
- Bokrantz, Tove, et al.
(författare)
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Antihypertensive drug classes and the risk of hip fracture: results from the Swedish primary care cardiovascular database.
- 2020
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Ingår i: Journal of hypertension. - 1473-5598. ; 38:1
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Tidskriftsartikel (refereegranskat)abstract
- Hypertension and fractures related to osteoporosis are major public health problems that often coexist. This study examined the associations between exposure to different antihypertensive drug classes and the risk of hip fracture in hypertensive patients.We included 59 246 individuals, 50 years and older, diagnosed with hypertension during 2001-2008 in the Swedish Primary Care Cardiovascular Database. Patients were followed from 1 January 2006 (or the date of diagnosis of hypertension) until they had their first hip fracture, died, or reached the end of the study on 31 December 2012. Cox proportional hazards models were used to calculate the risk of hip fracture across types of antihypertensive medications, adjusted for age, sex, comorbidity, medications, and socioeconomic factors.In total, 2593 hip fractures occurred. Compared to nonusers, current use of bendroflumethiazide or hydrochlorothiazide was associated with a reduced risk of hip fracture (hazard ratio 0.86; 95% CI 0.75-0.98 and hazard ratio 0.84; 95% CI 0.74-0.96, respectively), as was use of fixed drug combinations containing a thiazide (hazard ratio 0.69; 95% CI 0.57-0.83). Current use of loop diuretics was associated with an increased risk of hip fracture (hazard ratio 1.23; 95% CI 1.11-1.35). No significant associations were found between the risk of hip fracture and current exposure to beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aldosterone-receptor blockers or calcium channel blockers.In this large observational study of hypertensive patients, the risk of hip fracture differed across users of different antihypertensive drugs, results that could have practical implications when choosing antihypertensive drug therapy.
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| 2. |
- Rebbling, Anders, 1980-, et al.
(författare)
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Demonstrating Fuel Design To Reduce Particulate Emissions and Control Slagging in Industrial-Scale Grate Combustion of Woody Biomass
- 2020
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Ingår i: Energy & Fuels. - : AMER CHEMICAL SOC. - 0887-0624 .- 1520-5029. ; 34:2, s. 2574-2583
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Tidskriftsartikel (refereegranskat)abstract
- The demand for increased overall efficiency, improved fuel flexibility, and more stringent environmental legislations promotes the development of new fuel- and technology-related concepts for the bioenergy sector. Previous research has shown that careful consideration of the fuel ash composition and the adjustment of the same via various routes, i.e., fuel design, have the potential to alter the ash transformation reactions, leading to, e.g., a reduction of the formation of slag or entrained inorganic ash particles. The objective of the present work was, therefore, to demonstrate the use of fuel design as a primary measure to reduce the emission of PM1 during combustion of woody biomass in medium-scale grate-fired boilers while keeping the slag formation at a manageable level. This was achieved by designing fuel blends of woody biomass with carefully selected Scandinavian peats rich in Si, Ca, and S. The work includes results from three experimental campaigns, performed in three separate grate-fired boilers of different sizes, specifically 0.2 MWth, 2 MWth, and 4 MWth. In one of the campaigns, softwood-based stemwood pellets were copelletized with different additions of peat (5 and 15 wt %) before combustion. In the other campaigns, peat was added in a separate fuel feed to Salix chips (15 wt % peat) and softwood-based stemwood pellets (10 and 20 wt % peat). Particulate matter and bottom ashes were characterized by scanning electron microscopy-energy-dispersive X-ray spectroscopy for morphology and elemental composition as well as by powder X-ray diffraction for crystalline phase composition. The results show that the fuel design approach provided PM1 reduction for all fuel blends between 30 and 50%. The PM1 reduction could be achieved without causing operational problems due to slagging for any of the three commercial boilers used, although an expected increased slagging tendency was observed. Overall, this paper illustrates that fuel design can be implemented on an industrial scale by achieving the desired ash transformation reactions, in this case, leading to a reduction of fine particulate emissions by up to 50% without any operational disturbances due to slag formation on the grate.
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| 3. |
- Rebbling, Anders, 1980-, et al.
(författare)
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Prediction of slag related problems during fixed bed combustion of biomass by application of a multivariate statistical approach on fuel properties and burner technology
- 2020
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 137
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Tidskriftsartikel (refereegranskat)abstract
- Slag is related to the melting properties of ash and is affected by both the chemical composition of the fuel ash and the combustion parameters. Chemical analysis of slag from fixed bed combustion of phosphorus-poor biomass show that the main constituents are Si, Ca, K, O (and some Mg, Al, and Na), which indicates that the slag consists of different silicates. Earlier research also points out viscosity and fraction of the ash that melts, as crucial parameters for slag formation. To the authors’ knowledge, very few of the papers published to this day discuss slagging problems of different pelletized fuels combusted in multiple combustion appliances. Furthermore, no comprehensive classification of both burner technology and fuel ash parameters has been presented in the literature so far. The objective of the present paper was therefore to give a first description of a qualitative model where ash content, concentrations of main ash forming elements in the fuel and type of combustion appliance are related to slagging behaviour and potential operational problems of a biomass fuel in different small- and medium scale fixed bed appliances.Based on the results from the combustion of a wide range of pelletized biomass fuels in nine different burners, a model is presented for amount of slag formed and expected severity of operational problems. The model was validated by data collected from extensive combustion experiments and it can be concluded that the model predicts qualitative results.
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| 4. |
- Thyrel, Mikael, et al.
(författare)
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Phase transitions involving Ca - The most abundant ash forming element - In thermal treatment of lignocellulosic biomass
- 2021
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Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 285
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Tidskriftsartikel (refereegranskat)abstract
- Torrefaction, pyrolysis and gasification are of interest to convert lignocellulosic biomass into fuels and chemicals. These techniques involve thermal treatment at low partial pressures of oxygen. However, little is known about the transformation of ash elements during these processes. The phase transition of the major ash element calcium (Ca) was therefore studied with powder from pine as biomass model treated at temperatures 300-800 degrees C under atmospheres of 100% N-2, 3% O-2 and 6% O-2 and thermodynamic equilibrium modelling. For evaluation, Xray powder diffraction and synchrotron Ca K-edge X-ray absorption near edge structure (XANES) spectroscopy in combination with linear combination fitting and reference compounds was used. The results indicated that the most abundant Ca-containing species in the untreated material was thermally unstable Ca oxalate (CaC2O4) primarily decomposing into Ca phases dominated by carbonates at temperatures up to 600 degrees C. Double carbonates of calcium and potassium were observed in the form of fairchildiite/butscheliite (K2Ca(CO3)(2)), and these phases were stable over the low temperature range studied. Hydroxyapatite (Ca-5(PO4)(3)OH) was expected to be present and thermally stable over the entire temperature interval and was found in untreated material. At temperatures above 600 degrees C calcium oxide (CaO) was formed. The amount of oxygen had little effect on the phase transitions. The results of thermodynamic modeling were in agreement with XANES showing that this is a versatile technique that can be applied to systems as complex as Ca phase transitions in thermally treated lignocellulosic biomass at low partial pressures of oxygen.
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