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  • Bokrantz, Tove, et al. (författare)
  • Antihypertensive drug classes and the risk of hip fracture: results from the Swedish primary care cardiovascular database.
  • 2020
  • Ingår i: Journal of hypertension. - 1473-5598. ; 38:1
  • 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.
  • Boman, Christoffer, et al. (författare)
  • Stove Performance and Emission Characteristics in Residential Wood Log and Pellet Combustion, Part 1 : Pellet Stoves
  • 2011
  • Ingår i: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 25, s. 307-314
  • Tidskriftsartikel (refereegranskat)abstract
    • Stove performance, characteristics, and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter, and chimney draft. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NO(x), organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PM(tot)) as well as particle mass and number concentrations, size distributions, and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PM,, and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene, and benzene and the emissions of VOC varied in the range 1.1-42 mg/MJ(fuel). PAH emissions (2-340 mu g/MJ(fuel)) were generally dominated by phenanthrene, fluoranthene and pyrene. The PM(tot) values (15-45 mg/MJ(fuel)) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm, and number concentrations in the range 4 x 10(13) to 3 x 10(14) particles/MJ(fuel). During high load conditions, the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJ(fuel) consisting of potassium, sodium, sulfur, and chlorine, in the form of K(2)SO(4), K(3)Na(SO(4))(2), and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data.
  • Boström, Dan, et al. (författare)
  • Ash transformation chemistry during energy conversion of biomass
  • 2010
  • Ingår i: Proceedings of the International Conference on Impact of Fuel Quality on Power production and the Environment.
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • There is relatively extensive knowledge available concerning ash transformation reactions during energy conversion of woody biomass. Traditionally, these assortments have constituted the main resources for heating in Sweden. In recent decades the utilization of these energy carriers has increased, from a low technology residential small scale level to industrial scale (e.g. CHP plants). Along this evolution ash-chemical related phenomena for woody biomass has been observed and studied. So, presently the understanding for these are, if not complete, fairly good. Briefly, from a chemical point of view the ash from woody biomass could be characterized as a silicate dominated systems with varying content of basic oxides and with relatively high degree of volatilization of alkali sulfates and chlorides. Thus, the main ash transformation mechanisms in these systems have been outlined. Here, an attempt to give a general description of the ash transformation reactions of biomass fuels is presented, with the intention to provide guidance in the understanding of ash matter behavior in the utilization of any biomass fuel, primarily from knowledge of the concentrations of ash forming elements but also by considering the physical condition in the specific combustion appliance and the physical characteristic of the biomass fuel. Furthermore, since the demand for CO2-neutral energy resources has increased the last years and will continue to do so in the foreseeable future, other biomasses as for instance agricultural crops has become highly interesting. Globally, the availability of these shows large variation. In Sweden, for instance, which is a relatively spare populated country with large forests, these bio-masses will play a secondary role, although not insignificant. In other parts of the world, more densely populated and with a large agricultural sector, such bio-masses may constitute the main energy bio-mass resource in the future. However, the content of ash forming matter in agricultural bio-mass is rather different in comparison to woody biomass. Firstly, the content is much higher; from being about 0.3 - 0.5% (wt) in stem wood, it can amount to between 2 and 10 %(wt) in agricultural biomass. In addition, the composition of the ash forming matter is different. Shortly, the main difference is due to a much higher content of phosphorus (occasionally also silicon) which has major consequences on the ash-transformation reactions. In many crops, the concentration of phosphorus and silicon is equivalent, which (depending on the concentration levels of basic oxides) may result in a phosphate dominated ash. The properties of this ash are in several aspects different from the silicate dominated woody biomass ash and will consequently behave differently in various types of energy conversion systems. The knowledge about phosphate dominated ash systems has so far been scarce. We have been working with these systems, both with basic and applied research, for about a decade know. Some general experiences and conclusions as well as some specific examples of our research will be presented
  • Boström, Dan, et al. (författare)
  • Influence of kaolin and calcite additives on ash transformations in small-scale combustion of oat
  • 2009
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 23:10, s. 5184-5190
  • Tidskriftsartikel (refereegranskat)abstract
    • A growing interest has been observed for the use of cereal grains in small- and medium-scale heating. Previous studies have been performed to determine the fuel quality of various cereal grains for combustion purposes. The present investigation was undertaken in order to elucidate the potential abatement of low-temperature corrosion and deposits formation by using fuel additives (calcite and kaolin) during combustion of oat. Special emphasis was put on understanding the role of slag and bottom ash composition on the volatilization of species responsible for fouling and emission of fine particles and acid gases. The ash fractions were analyzed with scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), for elemental composition, and with X-ray diffraction (XRD) for identification of crystalline phases. The previously reported K and Si capturing effects of kaolin additive were observed also in the present study using P-rich biomass fuels. That is, the prerequisites for the formation of low melting K-rich silicates were reduced. The result of using kaolin additive on the bottom ash was that no slag was formed. The effect of the kaolin additive on the formation of submicrometer flue gas particles was an increased share of condensed K-phosphates at the expense of K-sulfate and KCl. The latter phase was almost completely absent in the particulate matter. Consequently, the levels of HCl and SO2 in the flue gases increased somewhat. The addition of both calcite assortments increased the amount of formed slag, although to a considerably higher extent for the precipitated calcite. P was captured to a higher degree in the bottom ash, compared to the combustion of pure oat. The effect of the calcite additives on the fine particle emissions in the flue gases was that the share of K-phosphate decreased considerably, while the content of K-sulfate and KCl increased. Consequently, also the flue-gas levels of acidic HCl and SO2 decreased. This implies that the low-temperature corrosion observed in small-scale combustion of oat possibly can be abated by employing calcite additives. Alternatively, if problems with slagging and deposition of corrosive matter at heat convection surfaces are to be avoided, kaolin additive can be utilized, on the condition that the higher concentrations of acidic gases can be tolerated.
  • Lindström, Erica, et al. (författare)
  • Influence of sand contamination on slag formation during combustion of wood derived fuels
  • 2008
  • Ingår i: Energy & Fuels. - 0887-0624 .- 1520-5029. ; 22:4, s. 2216-2220
  • Tidskriftsartikel (refereegranskat)abstract
    • Previous investigations have suggested that sand contamination to woody biomass fuels enhances slag formation in residential combustion appliances. The objectives were therefore to observe the effect of soil contamination in different forestry assortments on the extent of slagging and to gain increased understanding in the ash and slag forming chemical processes. This was accomplished by studying the bottom ash and the slag compositions after 19 2 h of combustion in a residential pellet burner. Melted ash reacted with the admixed sand particles resulting in an increased amount of melt with an increased content of silicon. The results confirm earlier experiences that melted bottom ash from combustion of woody biomass, upon cooling, forms silicate phases. In the corresponding melted ash, sand minerals as quartz, plagioclase, and microcline are not thermodynamically stable but will react and form a more silica rich melt. This melt has presumably lower liquidus temperature, explaining the increased amount of melt observed in the combustion experiments of soil contaminated fuels.
  • Lou, Benyong, et al. (författare)
  • Monohydrous dihydrogen phosphate salts of norfloxacin and ciprofloxacin
  • 2007
  • Ingår i: Acta Crystallographica Section C. - 0108-2701 .- 1600-5759. ; 63:12, s. 731-733
  • Tidskriftsartikel (refereegranskat)abstract
    • Norfloxacin and ciprofloxacin crystallize with phosphoric acid in aqueous solution to give the salts 4-(3-carboxy-1-ethyl-6-fluoro-4-oxo-1,4-dihydro-7-quinolyl)piperazinium dihydrogenphosphate monohydrate, C16H19FN3O3(+) x H2PO4(-) x H2O, and 4-(3-carboxy-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-7-quinolyl)piperazinium dihydrogenphosphate monohydrate, C17H19FN3O3(+) x H2PO4(-) x H2O, respectively. In the crystal structures, the phosphate anions and the piperazine rings of norfloxacin or ciprofloxacin form a 12-membered supramolecular synthon, viz. R4(4)(12). The synthons R4(4)(12) and R2(2)(8) formed between adjacent phosphate anions result in the three-dimensional structures.
  • Nordgren, Daniel, et al. (författare)
  • Ash transformations in pulverised fuel co-combustion of straw and woody biomass
  • 2013
  • Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 105, s. 52-58
  • Tidskriftsartikel (refereegranskat)abstract
    • Ash transformation processes have been studied during co-firing of wheat straw and pine stem wood and softwood bark. Pilot-scale trials in a 150kW pulverised-fuel-fired burner were performed. Thermodynamic equilibrium calculations were made to support the interpretation of the results. The results show that reactions involving condensed phases are kinetically limited compared to reactions between gaseous ash compounds. Accordingly, the conditions promote gas phase reactions resulting in the formation of chlorides, sulphates and carbonates whereas reactions involving condensed reactants are suppressed. Both the slagging and fouling propensities of all co-firing mixes were reduced compared to that for pure straw. For the wood/straw mixes this was mainly due to a dilution of the ash forming elements of straw whereas for straw/bark, an additional effect from interaction between the fuel ash components was observed to reduce slagging. In general it can be concluded that under powder combustion conditions equilibrium is approached selectively and that the ash matter is strongly fractionated. The general results in this paper are useful for straw-fired power stations looking for alternative co-firing fuels.
  • Stjernberg, Jesper, et al. (författare)
  • Deposit formation in a grate-kiln plant for iron-ore pellet production : Part 2: Characterization of deposits
  • 2013
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:10, s. 6171-6184
  • Tidskriftsartikel (refereegranskat)abstract
    • Buildup of deposit material in chunks on refractory linings caused by combustion of various fuels is a well-known problem. This study characterizes the short-term deposits on refractory material in a grate–kiln process, carried out through in situ measurements using a water-cooled probe with a part of a refractory brick mounted in its end. Sampling was carried out during combustion of both oil and coal. A significant difference in deposition rates was observed; deposition during oil firing was negligible compared to coal firing. The deposits are mainly hematite particles embedded in bonding phase, mainly comprising Si, Al, Fe, Ca, and O. Moreover, it was found that the prevailing flue-gas direction determines the formation of the deposits on the probe and that inertial impaction controls the deposition rate. However, this rate can also be affected by the amount of air-borne particles present in the kiln.
  • Wiinikka, Henrik, et al. (författare)
  • Influence of TiO2 additive on vaporization of potassium during straw combustion
  • 2009
  • Ingår i: Energy & Fuels. - 0887-0624 .- 1520-5029. ; 23:11, s. 5367-5374
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work, the influence of TiO2 on the vaporization of K during combustion of straw under fixed bed condition was investigated experimentally. Controlled combustion experiments with a varied amount of TiO2 in straw pellets were performed in an 8 kWpellet burner together with sampling of particles (impactor and absolute filter), analysis of the flue gas composition (Fourier transform infrared, FTIR), and chemical analyses of the collected particles and bottom ash (inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD)). The experimental results showed that the vaporization of K from the fuel bed was significantly reduced when TiO2 was used as an additive. The vaporization ofKwas reduced by∼40-50% for an optimal amount of TiO2 additive. The optimal added TiO2 for the straw used in this work corresponds to a Ti/K (wt) ratio between ∼0.6-1.0. If more TiO2 was added to the fuel, the release ofKto the gas phase was not further reduced and unreacted TiO 2 was found in the bottom ash. © 2009 American Chemical Society.
  • Xiong, Shaojun, et al. (författare)
  • Slagging characteristics during combustion of corn stovers with and without kaolin and calcite
  • 2008
  • Ingår i: Energy & Fuels. - 0887-0624 .- 1520-5029. ; 22:5, s. 3465-3470
  • Tidskriftsartikel (refereegranskat)abstract
    • Ash-related problems have more than occasionally been observed in biomass-fired boilers and also recently in biopellet burners. These problems can lead to reduced reliability of the combustion systems as well as bad publicity for the market. When agricultural residues are used as biofuel feedstock, slagging problems will be worse. The objectives of the present work were, therefore, to examine the effects of kaolin and calcite addition on the slagging tendency of corn stover fuel when corn stover pellets are burned in a small-scale appliance and determine the slag characteristics during combustion. Pellets with an additive/fuel ratio of 3% (dry mass) were combusted in an underfed burner (50 kW) that is installed in a boiler with 90 kW output. The choice of 3% additive/fuel ratio was based on analyses of the ash melting behavior of seven fuel mixtures that combine either 0-3% kaolin or 0-3% calcite and corn stovers. The 3% kaolin and calcite addition increased the ash melting temperature (IT) by about 100-200 °C. When the 3% kaolin or calcite was added to the corn stover raw material, the severe slagging tendency of the fuel was considerably reduced. The slag quantities from burning kaolin- and calcite-added fuels were about half and one-third, respectively, of that from nonadditive pellets. The slag deposits from the burner were characterized with scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDS) and X-ray diffraction (XRD). The XRD was also used to examine the chemical composition of corresponding bottom ash in the boiler. The results indicated that the reduction of slagging when using additives can be attributed to a change from relatively low melting temperature silicates to higher melting temperature silicates. For the corn stover without additives, the low melting fractions of the slag were assumed to consist mainly of potassium calcium silicate, indirectly observed as a glass by the XRD. When kaolin was added, a depletion of potassium was observed because of the extensive formation of leucite (KAlSi2O6) and the glass became dominated by calcium, aluminum, and silicon. This process was accompanied by a considerable reduction of glass amount. In the case of CaCO3 addition, however, calcium magnesium silicates formed to an extent that the glass (low melting material) finally became dominated by potassium silicate. This process was also accompanied by a substantial reduction of the amount of glass.
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