| 1. |
- Grubb, Anders, et al.
(författare)
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Generation of a new cystatin C-based estimating equation for glomerular filtration rate by use of 7 assays standardized to the international calibrator
- 2014
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 60:7, s. 974-986
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Many different cystatin C-based equations exist for estimating glomerular filtration rate. Major reasons for this are the previous lack of an international cystatin C calibrator and the nonequivalence of results from different cystatin C assays.METHODS:Use of the recently introduced certified reference material, ERM-DA471/IFCC, and further work to achieve high agreement and equivalence of 7 commercially available cystatin C assays allowed a substantial decrease of the CV of the assays, as defined by their performance in an external quality assessment for clinical laboratory investigations. By use of 2 of these assays and a population of 4690 subjects, with large subpopulations of children and Asian and Caucasian adults, with their GFR determined by either renal or plasma inulin clearance or plasma iohexol clearance, we attempted to produce a virtually assay-independent simple cystatin C-based equation for estimation of GFR.RESULTS:We developed a simple cystatin C-based equation for estimation of GFR comprising only 2 variables, cystatin C concentration and age. No terms for race and sex are required for optimal diagnostic performance. The equation, [Formula: see text] is also biologically oriented, with 1 term for the theoretical renal clearance of small molecules and 1 constant for extrarenal clearance of cystatin C.CONCLUSIONS:A virtually assay-independent simple cystatin C-based and biologically oriented equation for estimation of GFR, without terms for sex and race, was produced.
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| 2. |
- Malmgren, Linnea, et al.
(författare)
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The complexity of kidney disease and diagnosing it - Cystatin C, selective glomerular hypofiltration syndromes and proteome regulation.
- 2023
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Ingår i: Journal of Internal Medicine. - : John Wiley & Sons. - 0954-6820 .- 1365-2796. ; 293:3, s. 293-308
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Tidskriftsartikel (refereegranskat)abstract
- Estimation of kidney function is often part of daily clinical practice, mostly done by using the endogenous GFR-markers creatinine or cystatin C. A recommendation to use both markers in parallel in 2010 has resulted in new knowledge concerning the pathophysiology of kidney disorders by identification of a new set of kidney disorders, selective glomerular hypofiltration syndromes. These syndromes, connected to strong increases in mortality and morbidity, are characterised by a selective reduction in the glomerular filtration of 5-30 kDa molecules, such as cystatin C, compared to the filtration of small molecules < 1kDa dominating the glomerular filtrate e.g., water, urea, creatinine. At least two types of such disorders, shrunken or elongated pore syndrome, are possible according to the pore model for glomerular filtration. Selective glomerular hypofiltration syndromes are prevalent in investigated populations, and patients with these syndromes often display normal measured GFR or creatinine-based GFR-estimates. The syndromes are characterised by proteomic changes promoting the development of atherosclerosis, indicating antibodies and specific receptor-blocking substances as possible new treatment modalities. Presently, the KDIGO guidelines for diagnosing kidney disorders do not recommend cystatin C as a general marker of kidney function and will therefore not allow the identification of a considerable number of patients with selective glomerular hypofiltration syndromes. Furthermore, as cystatin C is uninfluenced by muscle mass, diet or variations in tubular secretion and cystatin C-based GFR-estimation equations do not require controversial race or sex terms, it is obvious that cystatin C should be a part of future KDIGO guidelines.
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| 3. |
- Akerstrom, Finn, et al.
(författare)
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Association between catheter ablation of atrial fibrillation and mortality or stroke
- 2024
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Ingår i: Heart. - : BMJ PUBLISHING GROUP. - 1355-6037 .- 1468-201X. ; 110, s. 163-169
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Tidskriftsartikel (refereegranskat)abstract
- Objective Catheter ablation of atrial fibrillation effectively reduces symptomatic burden. However, its long-term effect on mortality and stroke is unclear. We investigated if patients with atrial fibrillation who undergo catheter ablation have lower risk for all-cause mortality or stroke than patients who are managed medically. Methods We retrospectively included 5628 consecutive patients who underwent first-time catheter ablation for atrial fibrillation between 2008 and 2018 at three major Swedish electrophysiology units. Control individuals with an atrial fibrillation diagnosis but without previous stroke were selected from the Swedish National Patient Register, resulting in a control group of 48 676 patients. Propensity score matching was performed to produce two cohorts of equal size (n=3955) with similar baseline characteristics. The primary endpoint was a composite of all-cause mortality or stroke. Results Patients who underwent catheter ablation were healthier (mean CHA(2)DS(2)-VASc score 1.4 +/- 1.4 vs 1.6 +/- 1.5, p<0.001), had a higher median income (288 vs 212 1000 Swedish krona [KSEK]/year, p<0.001) and had more frequently received university education (45.1% vs 28.9%, p<0.001). Mean follow-up was 4.5 +/- 2.8 years. After propensity score matching, catheter ablation was associated with lower risk for the combined primary endpoint (HR 0.58, 95% CI 0.48 to 0.69). The result was mainly driven by a decrease in all-cause mortality (HR 0.51, 95% CI 0.41 to 0.63), with stroke reduction showing a trend in favour of catheter ablation (HR 0.75, 95% CI 0.53 to 1.07). Conclusions Catheter ablation of atrial fibrillation was associated with a reduction in the primary endpoint of all-cause mortality or stroke. This result was driven by a marked reduction in all-cause mortality.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Brus, Elisabet, et al.
(författare)
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Bed agglomeration characteristics of biomass fuels using blast-furnace slag as bed material
- 2004
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Ingår i: Energy & Fuels. - Washington, D.C. : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 18:4, s. 1187-1193
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Tidskriftsartikel (refereegranskat)abstract
- Agglomeration of bed material may cause severe operating problems during fluidized bed combustion. The attack or coating layers that are formed on the bed particles during combustion play an important role in the agglomeration process. To reduce bed agglomeration tendencies, alternative bed materials may be used. In this paper, bed agglomeration characteristics during the combustion of biomass fuels using a relatively new bed material (iron blast-furnace slag) as well as ordinary quartz sand were determined. Controlled agglomeration tests lasting 40 h, using five representative biomass fuels (bark, olive residue, peat, straw, and reed canary grass) were conducted in a bench-scale fluidized bed. The bed materials and agglomerates were analyzed using SEM/EDS and X-ray diffraction. Chemical equilibrium calculations were performed to interpret the experimental findings. The results showed that blast-furnace slag had a lower tendency to agglomerate than quartz sand for most of the fuels. The quartz particles showed an inner attack layer more often than did the blast-furnace slag. The blast-furnace slag had a lower tendency to react with elements from the fuel. The outer coating layer had similar characteristics and thickness for both bed materials when the same fuel was combusted. However, the inner attack layer thickness was larger for quartz particles. SEM/EDS analyses of the agglomerates showed that the inner Ca-K-silicate-rich attack layer was responsible for the agglomeration of quartz sand. The composition of blast-furnace slag agglomerate was similar to the outer coating layer. Chemical equilibrium calculations showed that the original composition of the blast-furnace slag was close to the equilibrium composition, and hence there was no major driving force for reactions between that bed material and K and Ca from the fuel. The homogeneous silica-rich attack layer (with a low melting temperature) was not formed to the same extent for blast-furnace slag, thus explaining the lower bed agglomeration tendency.
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| 9. |
- Delanaye, Pierre, et al.
(författare)
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CKD : A Call for an Age-Adapted Definition
- 2019
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 30:10, s. 1785-1805
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Forskningsöversikt (refereegranskat)abstract
- Current criteria for the diagnosis of CKD in adults include persistent signs of kidney damage, such as increased urine albumin-to-creatinine ratio or a GFR below the threshold of 60 ml/min per 1.73 m2 This threshold has important caveats because it does not separate kidney disease from kidney aging, and therefore does not hold for all ages. In an extensive review of the literature, we found that GFR declines with healthy aging without any overt signs of compensation (such as elevated single-nephron GFR) or kidney damage. Older living kidney donors, who are carefully selected based on good health, have a lower predonation GFR compared with younger donors. Furthermore, the results from the large meta-analyses conducted by the CKD Prognosis Consortium and from numerous other studies indicate that the GFR threshold above which the risk of mortality is increased is not consistent across all ages. Among younger persons, mortality is increased at GFR <75 ml/min per 1.73 m2, whereas in elderly people it is increased at levels <45 ml/min per 1.73 m2 Therefore, we suggest that amending the CKD definition to include age-specific thresholds for GFR. The implications of an updated definition are far reaching. Having fewer healthy elderly individuals diagnosed with CKD could help reduce inappropriate care and its associated adverse effects. Global prevalence estimates for CKD would be substantially reduced. Also, using an age-specific threshold for younger persons might lead to earlier identification of CKD onset for such individuals, at a point when progressive kidney damage may still be preventable.
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| 10. |
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| 11. |
- Khwaja, Salik, et al.
(författare)
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Entrained flow gasification of torrefied lignocellulosic biomass
- 2016
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Ingår i: Papers of the 24TH European Biomass Conference. - Amsterdam : ETA Florence Renewable Energies. ; , s. 1138-1142, s. 1138-1142
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Konferensbidrag (refereegranskat)abstract
- An extensive evaluation program was carried out within the European SECTOR project to evaluate the feasibility of torrefied and densified biomass in available entrained flow gasifiers. Different entrained flow reactors (both atmospheric and pressurized) in different scales, from lab scale to a 240 MW industrial gasifier were used for evaluation of torrefied materials as feedstock. Total behaviours of the new fuel throughout the whole supply chains and the EFG systems were evaluated and documented, including process behaviours in terms of operation, gas quality, products of incomplete gasification, etc. Results showed a significant improvement in fuel properties in terms of storage, logistics, milling and feeding behaviour by torrefaction and densification. Entrained flow gasification of the torrefied biomass was also shown to be feasible without any major showstoppers, even improving the gasification processes. Production of tars and other products of incomplete gasification were often found significantly reduced during gasification of torrefied material.
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| 12. |
- Larsson, Anders, et al.
(författare)
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Influence of black liquor variability, combustion, and gasification process variables and inaccuracies in thermochemical data on equilibrium modeling results
- 2006
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Ingår i: Energy & Fuels. - Washington : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 20:1, s. 359-363
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Tidskriftsartikel (refereegranskat)abstract
- The present work is a systematic sensitivity study of how inaccuracies in thermochemical data influence important parameters resulting from chemical equilibrium modeling of black liquor combustion and gasification processes. These effects have also been compared with those originating from normal variations in process variables and black liquor composition. Determination of the effects was achieved by performing a large number of equilibrium calculations structured according to statistical designs. Evaluation of the chemical equilibrium model calculations was facilitated by regression analysis. From the results, it can be concluded that uncertainties in thermochemical data of several key components have significant effects on important chemical and physical modeling responses in black liquor combustion and gasification. These effects are in many cases comparable to, or larger than, the effects from variation in fuel and process variables. Experimental redetermination of thermochemical data for Na2S, K2S, and gaseous NaOH is suggested.
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| 13. |
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| 14. |
- Lindberg, Gustav, et al.
(författare)
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Determination of thermodynamic properties of Na2S using solid-state EMF measurements
- 2007
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 39:1, s. 44-48
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Tidskriftsartikel (refereegranskat)abstract
- To obtain reliable thermodynamic data for Na2S(s), solid-state EMF measurements of the cell Pd(s)|O2(g)|Na2S(s), Na2SO4(s)|YSZ| Fe(s), FeO(s)|O2(g)ref| Pd(s) were carried out in the temperature range 870 < T/K < 1000 with yttria stabilized zirconia as the solid electrolyte. The measured EMF values were fitted according to the equation Efit/V (±0.00047) = 0.63650 − 0.00584732(T/K) + 0.00073190(T/K) ln (T/K). From the experimental results and the available literature data on Na2SO4(s), the equilibrium constant of formation for Na2S(s) was determined to be lg Kf(Na2S(s)) (±0.05) = 216.28 − 4750(T/K)−1 − 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as ΔfG(Na2S(s))/(kJ · mol−1) (±1.0) = 90.9 − 4.1407(T/K) + 0.5415849(T/K) ln (T/K). By applying third law analysis of the experimental data, the standard enthalpy of formation of Na2S(s) was evaluated to be ΔfH(Na2S(s), 298.15 K)/(kJ · mol−1) (±1.0) = −369.0. Using the literature data for Cp and the calculated ΔfH, the standard entropy was evaluated to S(Na2S(s), 298.15 K)/(J · mol−1 · K−1) (±2.0) = 97.0.
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| 15. |
- Ljung, Anders, et al.
(författare)
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Theoretical Feasibility for Ecological Biomass Ash Recirculation: Chemical Equilibrium Behavior of Nutrient Elements and Heavy Metals during Combustion
- 1997
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 31:9, s. 2499-2503
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Tidskriftsartikel (refereegranskat)abstract
- To obtain a sustainable increased use of the CO2-neutral biomass fuels, the nutrient elements in the ashes formed have to be recirculated back to the forest and farm lands. During their growth, plants accumulate significant amounts of heavy metals of anthropogenic origin, normally enriched in the ashes during the energy conversion processes. If some kind of heavy metal separation technique could be applied during or after the processes, a more ecologically safe ash fraction may be produced for the recirculation of the nutrients. In addition, contaminated soils could be efficiently cleaned by controlled cultivation and combustion of biomass fuels. Previous experimental results from full-scale combustion plants have indicated that a significant fraction of a heavy metal-free ash may be obtained at high temperatures due to the lower volatilization temperatures of these metals. In the present work, the theoretical feasibility of a proposed high-temperature cyclone separation technique was evaluated by means of chemical equilibrium model calculations. The equilibrium behavior of both nutrient elements (Ca, Mg, K, Na, P) and heavy metals (Cd, Cu, Cr, Pb, Ni, Zn, As, V) as functions of temperature was determined. The results indicate that Cd, Cu, Pb, and possibly As and Cr may be volatilized, and thus separated, through a hot cyclone (800-850 °C), still keeping all Ca, Mg, and P and 75% of K and Na in a condensed form in the cyclone ash.
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| 16. |
- Nordin, Sara, et al.
(författare)
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High Expression of Midkine in the Airways of Patients with Cystic Fibrosis.
- 2013
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Ingår i: American Journal of Respiratory Cell and Molecular Biology. - 1535-4989. ; 49:6, s. 935-942
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in the CFTR gene result in impaired host defense during cystic fibrosis (CF), where Pseudomonas aeruginosa becomes a key pathogen. We investigated the expression pattern of the antibacterial growth factor midkine in CF and possible interference with its activity by the altered airway microenvironment. High midkine expression was found in CF lung tissue compared with controls, involving epithelium of the large and small airways, alveoli, and cells of the submucosa (i.e. neutrophils and mast cells). In CF sputum, midkine was present at 100-fold higher levels but was also subject to increased degradation, compared with midkine in sputum from healthy controls. Midkine had a bactericidal effect on P. aeruginosa but increasing salt concentrations and low pH impaired the activity. Molecular modeling suggested that the effects of salt and pH were due to electrostatic screening and a charge-neutralization of the membrane, respectively. Both neutrophil elastase and elastase of P. aeruginosa cleaved midkine to smaller fragments, resulting in impaired bactericidal activity. Thus, midkine is highly expressed in CF but its bactericidal properties may be impaired by the altered microenvironment as reflected by the in vitro conditions used in this study.
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| 17. |
- Nyman, Ulf, et al.
(författare)
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The revised Lund-Malmo GFR estimating equation outperforms MDRD and CKD-EPI across GFR, age and BMI intervals in a large Swedish population
- 2014
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Ingår i: Clinical Chemistry and Laboratory Medicine. - : Walter de Gruyter GmbH. - 1434-6621 .- 1437-4331. ; 52:6, s. 815-824
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Tidskriftsartikel (refereegranskat)abstract
- Background: The performance of creatinine-based glomerular filtration rate (GFR) estimating equations may vary in subgroups defined by GFR, age and body mass index (BMI). This study compares the performance of the Modification of Diet in Renal Disease (MDRD) study and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations with the revised Lund-Malmo equation (LM Revised), a new equation that can be expected to handle changes in GFR across the life span more accurately. Methods: The study included 3495 examinations in 2847 adult Swedish patients referred for measurement of GFR (mGFR) 2008-2010 by plasma clearance of iohexol (median 52 mL/min/1.73 m(2)). Bias, precision [interquartile range (IQR)] and accuracy [percentage of estimates +/- 10% (P-10) and +/- 30% (P-30) of mGFR] were compared. Results: The overall results of LM Revised/MDRD/CKD-EPI were: median bias 2%/8%/11%, IQR 12/14/14 mL/min/1.73 m(2), P-10 40%/35%/35% and P-30 84%/75%/76%. LM Revised was the most stable equation in terms of bias, precision and accuracy across mGFR, age and BMI intervals irrespective of gender. MDRD and CKD-EPI overestimated mGFR in patients with decreased kidney function, young adults and elderly. All three equations overestimated mGFR and had low accuracy in patients with BMI <20 kg/m(2), most pronounced among men. Conclusions: In settings similar to the investigated cohort LM Revised should be preferred to MDRD and CKD-EPI due to its higher accuracy and more stable performance across GFR, age and BMI intervals.
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| 18. |
- Rollborn, Niclas, et al.
(författare)
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Good Agreement Between Hba1c Analyzed Using Capillary Electrophoresis, HPLC, Immunological and Enzymatic Methods
- 2019
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Ingår i: Journal of Diabetes, Metabolism and its Complications. ; 1:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Hemoglobin A1c (HbA1c) is an essential marker for assessment of glycemic control in diabetes patients. The aim of this study was to evaluate the agreement between different HbA1c methods.Methodology: We used blood samples to compare HbA1c results analyzed with Capillarys 3 Tera, Roche Tina-Quant HbA1c Gen 3, BioRad Variant II Turbo (3 sites), Mono S® and Abbott Architect enzymatic method. The comparisons were made as paired instrument comparisons with Capillarys 3 Tera.Results: The linear correlations between the HbA1c methods were as follows:Cobas 6000 = 0.982 x Capillarys 3 Tera + 0.975, R² = 0.994;Architect c8000 = 0.982 x Capillarys 3 Tera + 1.064, R² = 0.994; Mono S® = 0.916 x Capillarys 3 Tera + 3.397, R² = 0.965;BioRad Variant II Turbo = 0.923 x Capillarys 3 Tera + 4.062, R² = 0.990; Tosoh G8 = 0.963 x Capillarys 3 Tera + 3.895, R² = 0.996.Conclusions: The different instrument platforms showed the best agreement in the 50-70 mmol/mol interval. Above and below this range the methods separated into 2 groups, one consisting of Capillarys 3 Tera, Roche Tina-Quant and Abbott enzymatic method and the other group consisting of BioRad Variant II Turbo, Tosoh G8 and Mono S®.
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| 19. |
- Alstrup, Vagn, et al.
(författare)
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Lichenicolous fungi from the Skibotn area, Troms, Norway
- 2008
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Ingår i: Graphis Scripta. - Stockholm : NLF. - 0901-7593. ; 20:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Altogether 93 species of lichenicolous fungi are reported, the majority collected during the Nordic Lichen Society excursion in 2003 to the Skibotn area, Troms, Norway. Cornutispora ciliata, Intralichen cf. lichenum, Opegrapha stereocaulicola and Sphaerulina cf. dubiella are new to Scandinavia, 11 species are new to Norway, and further 42 are new to Troms. Stigmidium aggregata is also reported as new to Greenland. Host lichens, localities, collectors and collection numbers are given.
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| 20. |
- Arvedson, Mats, et al.
(författare)
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Packet or Circuit Switched Voice Radio Bearers-A Capacity Evaluation for GERAN
- 2002
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Konferensbidrag (refereegranskat)abstract
- GERAN, including the EDGE radio interface, con-stitutes the 3G evolution of GSM. The use of packet switched voice radio bearers has been discussed in the GERAN standardization, but has as yet not been adopted. This paper presents a thorough capacity comparison of circuit and packet switched voice bearers, applied to GERAN. Thus the standardization decision is verified, but also a framework for future similar investigations is provided. Several parameters affect the relative performance of circuit and packet switching. This report evaluates the effect of four of these parameters, expected to have major impact on the relative performance: reuse factor, resource pool size, voice activity, and additional overhead in the packet switched case. Varying the above parameters, it is seen that in certain blocking-limited scenarios packet switching may increase capacity significantly. The highest overall capacity is however achieved in inter-ference-limited scenarios, for which packet switching provides no capacity gain.
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| 21. |
- Bennermo, Marie, et al.
(författare)
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Genetic and environmental influences on the plasma interleukin-6 concentration in patients with a recent myocardial infarction : a case-control study
- 2011
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Ingår i: Journal of Interferon and Cytokine Research. - : Mary Ann Liebert Inc. - 1079-9907 .- 1557-7465. ; 31:2, s. 259-264
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to study the stimuli responsible for triggering and sustaining the plasma concentration of the inflammatory marker interleukin-6 (IL-6) in patients with a first myocardial infarction before the age of 60 and healthy control subjects matched for age and sex. The plasma IL-6 concentration, antibodies against Chlamydia pneumoniae, cytomegalovirus, Epstein-Barr virus, Helicobacter pylori, herpes simplex type 1 and 2, and genotype for the IL6-174 G>C single-nucleotide polymorphism were determined 3 months after the acute event. The results showed that patients had higher IL-6 levels than control subjects, whereas there were no differences regarding individual or total number (pathogen burden) of positive antibody tests against the different pathogens or IL6 genotype distribution. The plasma IL-6 concentration was associated with the number of positive antibody tests in patients and control subjects, whereas patients irrespective of IL6 genotype had increased IL-6. Multivariate analysis, including traditional coronary heart disease risk factors, antibodies against pathogens, and IL6 genotype, explained 17% of the variation of the plasma IL-6 concentration. Neither pathogen burden nor IL6 genotype did contribute to the variation of plasma IL-6 levels, whereas smoking, body-mass index, hypertension, case-control status, and age were determinants of the plasma IL-6 concentration.
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| 22. |
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| 23. |
- Boman, Christoffer, et al.
(författare)
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Characterization of inorganic particulate matter from residential combustion of pelletized biomass fuels
- 2004
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 18:2, s. 338-348
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Tidskriftsartikel (refereegranskat)abstract
- The increased focus on potential adverse health effects associated with exposure to ambient particulate matter (PM) motivates a careful characterization of particle emissions from different sources. Combustion is a major anthropogenic source of fine PM, and, in urban areas, traditional residential wood combustion can be a major contributor. New and upgraded biomass fuels have become more common, and fuel pellets are especially well-suited for the residential market. The objective of the present work was to determine the mass size distributions, elemental distributions, and inorganic-phase distributions of PM from different residential combustion appliances and pelletized biomass fuels. In addition, chemical equilibrium model calculations of the combustion process were used to interpret the experimental findings. Six different typical pellet fuels were combusted in three different commercial pellet burners (10-15 kW). The experiments were performed in a newly designed experimental setup that enables constant-volume sampling. Total-PM mass concentrations were measured using conventional filters, and the fractions of products of incomplete combustion and inorganic material were thermally determined. Particle mass size distributions were determined using a 13-step low-pressure cascade impactor with a precyclone. The PM was analyzed for morphology (using environmental scanning electron microscopy, ESEM), elemental composition (using energy-dispersive spectroscopy, EDS), and crystalline phases (using X-ray diffractometry, XRD). For complementary chemical structural characterization, time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy XPS and X-ray absorption fine structure (XAFS) spectroscopy were also used. The emitted particles were mainly found in the fine ( less than or equal 1 μm) mode with mass median aerodynamic diameters of 0.20 - 0.39 μm and an average PM1 of 89.5% ± 7.4% of total PM. Minor coarse-mode fractions (>1 μm) were present primarily in the experiments with bark and logging residues. Relatively large and varying amounts (28%-92%) were determined to be products of incomplete combustion. The inorganic elemental compositions of the fine particles were dominated by potassium, chlorine, and sulfur, with minor amounts of sodium and zinc. The dominating alkali phase was KCl, with minor but varying amounts of K3Na(SO4)2 and, in some cases, also K2SO4. The results showed that zinc is almost fully volatilized, subsequently and presumably forming a more complex solid phase than that previously suggested (ZnO). However, the formation mechanism and exact phase identification remain to be elucidated. With some constrains, the results also showed that the amounts and speciation of the inorganic PM seemed to be quite similar to that predicted by chemical equilibrium calculations.
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| 24. |
- Boman, Christoffer, 1970-, et al.
(författare)
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Effects of increased small-scale biomass pellet combustion on ambient air quality in residential areas : A parametric dispersion modeling study
- 2003
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 24:6, s. 465-474
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Tidskriftsartikel (refereegranskat)abstract
- Sweden's goals of contemporaneously reducing CO2 emissions and phasing out nuclear power will require a maximum utilization of biomass fuels. This would imply a significant shift from electricity and fuel oil to biomass generated heat, but must also be accomplished without a deterioration of the local air quality. The most suitable energy carrier seems to be pelletized biomass fuels with their associated low emissions and considerable residential conversion potential. Using an underlying statistical design, a parametric dispersion modeling study was performed to estimate and illustrate the combined effects of source-specific, meteorological and modeling variables on the ambient air quality in a typical residential area for different conversion scenarios. The work nicely illustrated the benefits of combining statistical designs with model calculations. It further showed that the concentration of combustion related ambient THC was strongly related to conditions affecting the source strength, but only weakly to the dispersion conditions and model variables. Time of year (summer or winter); specific emission performance; extent of conversion from electricity; conversion from wood log combustion; and specific efficiency of the pellet appliances showed significant effects in descending order. The effects of local settings and model variables were relatively small, making the results more generally applicable. To accomplish the desired conversion to renewable energy in an ecologically and sustainable way, the emissions would have to be reduced to a maximum advisable limit of (given as CH4). Further, the results showed the potential positive influence by conversion from wood log to low emission pellet combustion.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Boman, Christoffer, et al.
(författare)
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Evaluation of a constant volume sampling setup for residential biomass fired appliances : Influence of dilution conditions on particulate and PAH emissions
- 2005
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 29:4, s. 258-268
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Tidskriftsartikel (refereegranskat)abstract
- Increased concerns about particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) emissions from residential biomass combustion and their potential health effects, motivates detailed emission measurements under controlled conditions. Traditional sampling in raw flue gases can suffer from drawbacks mainly related to transient flows and the condensable nature of organic compounds. Whole flow dilution with constant volume sampling (CVS) is an alternative method but different sampling conditions may, however, influence the emission characteristics. The objective was to design a CVS system for emission measurements in residential biomass fired appliances and determine the influence of dilution sampling conditions on the characteristics and distributions of PM and PAH. Softwood pellets were combusted in a pellet stove with variations in; dilution ratio (3-7x), sampling temperature (45-75°C), dilution tunnel residence time (2-4 s) and fuel load (2.3 and 4.8 kW) according to a statistical experimental design. The sampling conditions did not influence either the emission concentrations of PM, CO and NO or the particle size distribution. Variations in residence time had no significant effect on any studied emission parameter. However, increased concentrations of organic gaseous carbon (OGC) and PAH were observed with increased dilution ratio. The distribution between particulate and semivolatile phase was influenced for 12 of the 37 analyzed PAH compounds, mainly by increased fractions of semivolatile material at higher sampling temperature. No influence of sampling temperature was observed for the concentrations of PAHtot or the dominating PAH compounds, i.e. phenanthrene, fluoranthene and pyrene. The results together with practical considerations also suggest sampling at 50±5°C and 3-4 times dilution as robust and applicable conditions in the presently designed setup. © 2005 Elsevier Ltd. All rights reserved.
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| 29. |
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| 30. |
- Boman, Christoffer, 1970-
(författare)
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Particulate and gaseous emissions from residential biomass combustion
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biomass is considered to be a sustainable energy source with significant potentials for replacing electricity and fossil fuels, not at least in the residential sector. However, present wood combustion is a major source of ambient concentrations of hydrocarbons (e.g. VOC and PAH) and particulate matter (PM) and exposure to these pollutants have been associated with adverse health effects. Increased focus on combustion related particulate emissions has been seen concerning the formation, characteristics and implications to human health. Upgraded biomass fuels (e.g. pellets) provide possibilities of more controlled and optimized combustion with less emission of products of incomplete combustion (PIC´s). For air quality and health impact assessments, regulatory standards and evaluations concerning residential biomass combustion, there is still a need for detailed emission characterization and quantification when using different fuels and combustion techniques.This thesis summarizes the results from seven different papers. The overall objective was to carefully and systematically study the emissions from residential biomass combustion with respect to: i) experimental characterization and quantification, ii) influences of fuel, appliance and operational variables and iii) aspects of ash and trace element transformations and aerosol formation. Special concern in the work was on sampling, quantification and characterization of particulate emissions using different appliances, fuels and operating procedures.An initial review of health effects showed epidemiological evidence of potential adverse effect from wood smoke exposure. A robust whole flow dilution sampling set-up for residential biomass appliances was then designed, constructed and evaluated, and subsequently used in the following emission studies. Extensive quantifications and characterizations of particulate and gases emissions were performed for residential wood and pellet appliances. Emission factor ranges for different stoves were determined with variations in fuel, appliance and operational properties. The emissions of PIC´s as well as PMtot from wood combustion were in general shown to be considerably higher compared to pellets combustion. PAHtot emissions were determined in the range of 1300-220000 µg/MJ for wood stoves and 2-300 µg/MJ for pellet stoves with phenantrene, fluoranthene and pyrene generally found as major PAH´s. The PM emissions from present residential appliances was found to consist of significant but varying fractions of PIC´s, with emissions in the range 35-350 mg/MJ for wood stoves compared to 15-45 mg/MJ for pellet stoves. Accordingly, the use of up-graded biomass fuels, combusted under continuous and controlled conditions give advantageous combustion conditions compared to traditional batch wise firing of wood logs. The importance of high temperature in well mixed isothermal conditions was further illustrated during pellets combustion to obtain complete combustion with almost a total depletion of PIC´s. Fine (100-300 nm) particles dominated in all studied cases the PM with 80-95% as PM1. Beside varying fractions of carbonaceous material, the fine PM consisted of inorganic volatilized ash elements, mainly found as KCl, K3Na(SO4)2 and K2SO4 with mass concentrations at 15-20 mg/MJ during complete combustion. The importance of the behavior of alkali elements for the ash transformation and fine particle formation processes was further shown, since the stability, distributions and compositions also directly control the degree of volatilization. In addition to the alkali metals, zinc was found as an important element in fine particles from residential biomass combustion. Finally, the behaviour of volatile trace elements, e.g. Zn and Cd, during pellets production and combustion were studied. A significant enrichment in the pellet fuel during the drying process was determined. The magnitude and importance of the enrichment was, however, relative small and some alternative measures for prevention were also suggested.
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| 31. |
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| 32. |
- Boman, Christoffer, et al.
(författare)
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Stove performance and emission characteristics in residential wood log and pellet combustion : Part 1: Pellet stoves
- 2011
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25:1, s. 307-314
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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 draught. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) 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 PMtot 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 1.1-47 mg/MJfuel. PAH emissions (2-340 µg/MJfuel) were generally dominated by phenantrene, fluoranthene and pyrene. PMtot (15-45 mg/MJfuel) 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 4×1013- 3×1014 particles/MJfuel. During high load conditions the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJfuel consisting of potassium, sodium, sulfur and chlorine, in the form of K2SO4, K3Na(SO4)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.
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| 33. |
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| 34. |
- Boman, Christoffer, et al.
(författare)
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Trace element enrichment and behavior in wood pellet production and combustion processes
- 2006
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 20:3, s. 993-1000
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Tidskriftsartikel (refereegranskat)abstract
- The extensive and well-documented concerns regarding environmental dispersion of toxic trace metals constitute solid motives for a special focus of their fate and forms in fuel treatment and conversion processes. The potential enrichment of trace elements during fuel pellet production processes and behavior during combustion was, therefore, studied in a combined field sampling and chemical equilibrium modeling work. Raw materials, pellet fuels, and particulate matter in the drying gases in two different pelletizing plants were sampled and analyzed. In addition, chemical equilibrium model calculations were performed with variations in the content of trace elements, moisture, sulfur, and chlorine, at both oxidizing and reducing conditions. A significant enrichment of Zn, Cu, Cd, and Pb was documented when using bark combustion gases for direct drying of the sawdust and was also supported by the chemical equilibrium results. This is presumably caused by the volatilization of these elements from the bark fuel during combustion, subsequently forming fine particles in the flue gases and being captured by the sawdust during drying. The magnitude and importance for these trace elements were, however, found to be relatively small, regarding concentrations in different fuels as well as potential increased emissions to air during combustion compared to national total emission estimations. In addition, some alternative measures for prevention of trace metal contamination during fuel pellet production were suggested, including fuel quality aspects, high-temperature particle separation, and indirect drying processes.
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| 35. |
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| 36. |
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| 37. |
- Boraxbekk, Carl-Johan, 1980-, et al.
(författare)
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Free Recall Episodic Memory Performance Predicts Dementia Ten Years prior to Clinical Diagnosis : Findings from the Betula Longitudinal Study
- 2015
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Ingår i: Dementia and Geriatric Cognitive Disorders Extra. - : S. Karger AG. - 1664-5464. ; 5:2, s. 191-202
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Early dementia diagnosis is a considerable challenge. The present study examined the predictive value of cognitive performance for a future clinical diagnosis of late-onset Alzheimer's disease or vascular dementia in a random population sample. Methods: Cognitive performance was retrospectively compared between three groups of participants from the Betula longitudinal cohort. Group 1 developed dementia 11-22 years after baseline testing (n = 111) and group 2 after 1-10 years (n = 280); group 3 showed no deterioration towards dementia during the study period (n = 2,855). Multinomial logistic regression analysis was used to investigate the predictive value of tests reflecting episodic memory performance, semantic memory performance, visuospatial ability, and prospective memory performance. Results: Age-and education-corrected performance on two free recall episodic memory tests significantly predicted dementia 10 years prior to clinical diagnosis. Free recall performance also predicted dementia 11-22 years prior to diagnosis when controlling for education, but not when age was added to the model. Conclusion: The present results support the suggestion that two free recall-based tests of episodic memory function may be useful for detecting individuals at risk of developing dementia 10 years prior to clinical diagnosis.
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| 38. |
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| 39. |
- Borén, Eleonora, et al.
(författare)
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Off-gassing from 16 pilot-scale produced pellets assortments of torrefied pine : impact of torrefaction severity, storage time, pelletization parameters, and pellet quality
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Off-gassing from wood pellets poses risks in large scale handling chains - yet little is known on off-gassing from pellets of torrefied wood. This study reports CO, CO2, and O2 concentrations in off-gases during storage of 16 torrefied and two untreated pellets assortments. According to an experimental design, pellets were produced in pilot scale from pine chips torrefied at five different set points. Off-gassing was assessed in relation to storage conditions, torrefaction and pelletization parameters, and pellet quality. Pellets from the most severely torrefied pine formed CO, CO2, and consumed O2 similarly to untreated pellets. Off-gassing was positively correlated to pellet moisture content; however, the most severely torrefied also retained the least moisture. Open air storage (20–270 days) of torrefied chips prior to pelletization did not affect off-gassing levels. Results are important for safe handling; torrefied pellets can cause comparable levels as untreated pellets of CO, CO2, and O2.
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| 40. |
- Borén, Eleonora, et al.
(författare)
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Off-gassing from pilot-scale torrefied pine wood chips : impact of torrefaction severity, cooling technology, and storage time
- 2020
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Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 202
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Tidskriftsartikel (refereegranskat)abstract
- During handling and storage of conventional wood pellets, O2 depletion as well as CO and CO2 off-gassing can reach acutely hazardous levels and certain Volatile Organic Compounds (VOCs) may reach concerning levels from an occupational health and safety perspective. With new thermally pre-treated biomass commodities entering consumer markets, corresponding knowledge is needed on these assortments' off-gassing behaviour. In this study, relative concentrations of VOCs, CO, CO2, and O2 in the closed storage space of five different pilot-scale torrefied pine wood chip assortments were monitored over 12 days. The VOCs composition in the storage space differed between torrefaction treatment settings; terpenes decreased while furans and lignin degradation products peaked at narrow ranges with increased torrefaction severity, indicating that VOC off-gassing composition of individual compounds is highly specific. Generally, VOC amounts decreased with storage time, but for the mildest torrefied chips certain VOCs increased, predominantly compounds of higher volatility such as hexanal, acetone, and 2-pentylfuran. Also, the newly produced torrefied chips were cooled with two different post-process technologies: i) heat exchanging, and ii) heat exchanging with additional water spraying. Water spraying resulted in higher VOC concentrations, stronger O2 depletion, and factor four higher concentration of CO2 in the storage headspace.
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| 41. |
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| 42. |
- Brattsand, Göran, et al.
(författare)
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Equalis/SFKK rekommenderar harmonisering av enheter vid hormonbestämningar -Något också för Norden?
- 2012
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Ingår i: Klinisk Biokemi i Norden. - 1101-2013. ; 24:4, s. 20-27
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Tidskriftsartikel (refereegranskat)abstract
- Equalis och Svensk Förening för Klinisk Kemi (SFKK) rekommenderar att de kliniska laboratorierna i Sverige använder enhetliga måttenheter vid hormonbestämningar för ökad jämförbarhet och patientsäkerhet. Vid analys i serum eller plasma med nuvarande metoder rekommenderas följande enheter:• Adrenokortikotropt hormon (ACTH): pmol/L• Insulin: mIE/L• Parathormon (PTH): pmol/L• Prolaktin: mIE/L• Tillväxthormon (GH): μg/L• Östradiol: pmol/L• Aldosteron: pmol/L• Reninkoncentration: mIE/L
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| 43. |
- Brostrom, Markus, et al.
(författare)
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Influence of torrefaction on the devolatilization and oxidation kinetics of wood
- 2012
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 96, s. 100-109
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Tidskriftsartikel (refereegranskat)abstract
- Devolatilization and oxidation kinetics of torrefied wood have been studied by evaluating thermogravimetric curves measured in nitrogen and air at various heating rates. Samples consist of Norway spruce wood chips torrefied at several process temperatures and residence times. Data about untreated wood have also been obtained for comparison. Measured curves are well predicted by means of a five-reaction mechanism, consisting of three devolatilization reactions for the pseudo-components hemicellulose. cellulose and lignin and, in air, of two additional reactions for char devolatilization and combustion. The torrefaction pre-treatment only requires model modifications in the amounts of volatiles generated from the decomposition of pseudo-components, indicating that only their relative percentages and not their reactivities are modified. On the other hand, a slightly different thermal stability is found for the char generated from torrefied wood, which results in higher activation energy and lower reaction order for the oxidation step. Hence torrefaction conditions can affect the subsequent conversion characteristics of the char product. (C) 2012 Elsevier B.V. All rights reserved.
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| 44. |
- Broström, Markus, et al.
(författare)
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IACM - In situ alkali chloride monitor
- 2004
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Ingår i: 2nd World Conference for Energy, Industry and Climate Protection, Rome, Italy.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 45. |
- Broström, Markus, 1977-, et al.
(författare)
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Sulfation of corrosive alkali chlorides by ammonium sulfate in a biomass fired CFB boiler
- 2007
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Ingår i: Fuel processing technology. - Amsterdam : Elsevier Bv. - 0378-3820 .- 1873-7188. ; 88:11-12, s. 1171-1177
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Tidskriftsartikel (refereegranskat)abstract
- Biomass and waste derived fuels contain relatively high amounts of alkali and chlorine, but contain very little sulfur. Combustion of such fuels can result in increased deposit formation and superheater corrosion. These problems can be reduced by using a sulfur containing additive, such as ammonium sulfate, which reacts with the alkali chlorides and forms less corrosive sulfates. Ammonium sulfate injection together with a so-called in situ alkali chloride monitor (IACM) is patented and known as "ChlorOut". IACM measures the concentrations of alkali chlorides (mainly KCl in biomass combustion) at superheater temperatures. Tests with and without spraying ammonium sulfate into the flue gases have been performed in a 96MW(th)/25MW(e) circulating fluidized bed (CFB) boiler. The boiler was fired mainly with bark and a chlorine containing waste. KCl concentration was reduced from more than 15 ppm to approximately 2 ppm. during injection of ammonium sulfate. Corrosion probe measurements indicated that both deposit formation and material loss due to corrosion were decreased using the additive. Analysis of the deposits showed significantly higher concentration of sulfur and almost no chlorine in the case with ammonium sulfate. Results from impactor measurements supported that KCl was sulfated to potassium sulfate by the additive. (C) 2007 Elsevier B.V. All rights reserved.
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| 46. |
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| 47. |
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| 48. |
- Brus, Elisabet, et al.
(författare)
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Mechanisms of bed agglomeration during fluidized-bed combustion of biomass fuels
- 2005
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 19:3, s. 825-832
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Tidskriftsartikel (refereegranskat)abstract
- The major ash-related problem encountered in fluidized beds is bed agglomeration, which, in the worst case, may result in total defluidization of the bed and unscheduled downtime. Because of the special ash-forming constituents of biomass fuels, several of these fuels have been shown to be especially problematic. Despite the frequent reporting, a precise and quantitative knowledge of the bed agglomeration process during fluidized bed combustion of biomass fuels has not yet been presented. Bed sampling versus operation time was performed in four different biomass-fired full-scale fluidized beds, as well as during controlled fluidized bed agglomeration tests in bench-scale testing of five representative biomass fuels. The bed materials and agglomerates were further analyzed using scanning electron microscopy, coupled with energy-dispersive spectroscopy SEM/EDS, to determine the characteristics of the formed bed particle layers. For typical wood fuels, coating-induced agglomeration with subsequent attack reaction and diffusion by calcium into the quartz was identified to be the dominating bed agglomeration mechanism. Low-melting calcium-based silicates (including minor amounts of, for example, potassium) were formed with subsequent viscous-flow sintering and agglomeration. For high-alkali-containing biomass fuels, direct attack of the quartz bed particle by potassium compounds in a gas or aerosol phase formed a layer of low-melting potassium silicate. Thus, formation and subsequent viscous-flow sintering and agglomeration seemed to be the dominating agglomeration mechanism for these fuels.
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| 49. |
- Bungartz, Frank, et al.
(författare)
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Buellia
- 2008
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Ingår i: Lichen Flora of the Greater Sonoran Desert Region, vol. 3.. - Arizona State University, Tempe : Lichens Unlimited. ; , s. 113-179
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 50. |
- Carolin, Anders, et al.
(författare)
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Concrete beams strengthened with near surface mounted reinforcement of CFRP
- 2001
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Ingår i: FRP Composites in Civil Engineering. - Amsterdam : Elsevier. - 0080439454 ; , s. 1059-1066
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Konferensbidrag (refereegranskat)abstract
- The size of loads wearing on the railroad and highway systems have increased in recent years. For concrete structures with a very long life and also under difficult conditions, it is not uncommon that measures must be taken to improve the structure's durability or its load bearing capacity. Recently, the use of advanced composites in external bonding of extra reinforcement has become an accepted method. However, there are some drawbacks to this method, including that the pretreatment of the concrete surface is highly work intensive and time consuming, as well as quality concerns. With the improved plate bonding presented in this paper, the aforementioned problems are less troublesome. The technique has also been tested with a cementitious bonding agent.
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