| 1. |
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| 2. |
- Ström, Linda, 1985, et al.
(author)
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Catalytically Active Pd–Ag Alloy Nanoparticles Synthesized in Microemulsion Template
- 2018
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In: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 34:33, s. 9754-9761
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Journal article (peer-reviewed)abstract
- This work investigates the possibility to form catalytically active bimetallic Pd–Ag nanoparticles synthesized in the water pools of a reversed microemulsion using methanol, a more environmental- and user-friendly reductant compared to hydrazine or sodium borohydride, which are commonly used for this type of synthesis. The nanoparticles were characterized with regards to crystallinity and size by X-ray diffraction and transmission electron microscopy. CO chemisorption and oxidation followed by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used for investigating the elemental composition of the surface and catalytic activity, respectively. Moreover, the structural composition of the bimetallic particles was determined by scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. The particles were shown to be crystalline nanoalloys of around 5–12 nm. CO adsorption followed by in situ DRIFTS suggests that the particle surfaces are composed of the same Pd–Ag ratios as the entire particles, regardless of elemental ratio (i.e., no core–shell structures can be detected). This is also shown by numerical simulations using a Monte Carlo based model. Furthermore, CO oxidation confirms that the synthesized particles are catalytically active.
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| 3. |
- Ström, Linda, 1985, et al.
(author)
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Quantification of urea-spray non-uniformity effects on the H2-assisted NO reduction and NH3 slip over an Ag/Al2O3 catalyst
- 2015
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In: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 75, s. 2317-2322
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Conference paper (peer-reviewed)abstract
- Selective catalytic reduction of nitrogen oxides (NOx) with ammonia (NH3-SCR) is an efficient technology for lean NOx removal in automotive applications. In the current work, a kinetic model for hydrogen-assisted NH3-SCR over a silver-alumina (Ag/Al2O3) monolith catalyst is adapted to the corresponding experimental results. The degree of non-uniformity in the NH3 dose to individual catalyst channels during operation of a urea-SCR system is also investigated and the NH3 dose probability distribution functions are derived. The effects of NH3 non-uniformity on the NO conversion and NH3 slip are studied over an otherwise optimal Ag/Al2O3 system. Above the stoichiometric point, the NH3 slip is shown to increase almost linearly with increasing NH3 dosage. Channels that receive significantly lower NH3 dose than the stoichiometric one exhibit low NO conversion, whereas there is no discernable increase in the NO conversion above an NH3 dose four times the average. These results highlight the importance of the interaction between the design of the NH3 dosing system and the performance of the catalytic system.
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| 4. |
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| 5. |
- Chaplin, John, et al.
(author)
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Varför ska du använda PROMIS? : Nytt system för patientrapporterad utfallsmått
- 2018
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Conference paper (other academic/artistic)abstract
- PROMIS är ett itembanksystem för hälso- och sjukvården. Syftet är att erbjuda moderna, patientrapporterade mått som kan användas för flertalet patientgrupper till en mycket låg kostnad och med ett nationellt supportsystem.En itembankär en modern form av elektronisk enkät som kan innehålla ett stort antal enkätfrågor. Ett datorprogram väljer ut de mest lämpade frågorna till varje person utifrån dennes svar på föregående frågor, på så sätt enkäten individanpassas.
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| 6. |
- Ekenros, Linda, et al.
(author)
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Perceived impact of the menstrual cycle and hormonal contraceptives on physical exercise and performance in 1,086 athletes from 57 sports
- 2022
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In: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 13
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Journal article (peer-reviewed)abstract
- Female athletes train and compete under the potential influence of hormonal fluctuations during the menstrual cycle or during use of various hormonal contraceptives. Dysmenorrhea and premenstrual symptoms are common in the general population, as well as side effects of hormonal contraceptives. More detailed knowledge concerning prevalence and perceived impact of these symptoms on training and performance in different sports is required. The aim of the study was to 1) characterize perceptions of training and performance during the menstrual cycle phases and by hormonal contraceptive use in a large population of female athletes; 2) explore whether symptoms experienced are related to perceived performance; and 3) examine potential differences in these factors between athletes at different levels of performance. The study was based on self-reported data from 1,086 athletes from 57 sports at different performance levels via a web-based questionnaire. Thirty-seven percent (n = 407) of the athletes did not use hormonal contraceptives. In this group, menstrual cycle related symptoms were common across all athlete levels, particularly dysmenorrhea (74%, n = 300) and premenstrual symptoms (78%, n = 318), which also influenced perceived performance of aerobic fitness, muscle strength, mental sharpness, balance, and sleep quality. Sixty-three percent (n = 679) of the athletes used various hormonal contraceptives and 40% (n = 272) perceived a variety of side-effects. Physical performance was experienced equally independent of time-point of the pill-chart except for the period of inactive pills, which was associated with more negative impact. Nonetheless, only 18% (n = 191) of the athletes considered menstrual cycle or hormonal contraceptive issues when planning their training or competitions. These results indicate that greater focus is needed to identify and effectively treat different menstrual cycle and hormonal contraceptive related symptoms on an individual level.
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| 7. |
- Fälth, Linda, 1973-, et al.
(author)
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Intensive Phonological Training With Articulation-An Intervention Study to Boost Pupils' Word Decoding in Grade 1
- 2020
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In: Journal of Cognitive Education and Psychology. - : Springer. - 1945-8959 .- 1810-7621. ; 19:2, s. 161-171
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Journal article (peer-reviewed)abstract
- The aim of this study is to examine how a structured intensive training period with a phonological multisensory reading training method, at the end of Grade 1, can develop pupils' ability to connect phonemes with the corresponding graphemes as well as their ability to decode. A total of 38 pupils in Grade 1 from four elementary schools participated in this randomized controlled trial (RCT) study. Of the 38 pupils 19 were randomly assigned to be part of the intervention group, the other 19 were included in the control group. The intervention involved 30 minutes of intensive training on a total of 20 sessions. The control group participated in regular reading lessons in the classroom. The study included pre- and posttesting of phonological awareness, letter knowledge, and decoding. The result shows that intensive phonological awareness training with articulation, during 20 sessions spread over 4-5 weeks, stimulates pupils' decoding ability in a positive direction.
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| 8. |
- Gad, Helge, et al.
(author)
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MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
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In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
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Journal article (peer-reviewed)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
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| 9. |
- Gerdin, Linda, et al.
(author)
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The Swedish Crohn Trial: A Prematurely Terminated Randomized Controlled Trial of Thiopurines or Open Surgery for Primary Treatment of Ileocaecal Crohns Disease
- 2016
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In: Journal of Crohn's & Colitis. - : OXFORD UNIV PRESS. - 1873-9946 .- 1876-4479. ; 10:1, s. 50-54
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Journal article (peer-reviewed)abstract
- Background and aims: The importance of efficient and safe treatment of Crohns disease is highlighted by its chronicity. Both medical and surgical treatments have shown good results in the symptomatic control of limited ileocaecal Crohns disease. The aim of this study was to compare medical treatment with surgical treatment of ileocaecal Crohns disease. Methods: Thirty-six patients from seven hospitals with primary ileocaecal Crohns disease were randomized to either medical or surgical treatment. The medical treatment was induction of remission with budesonide and thereafter maintenance treatment with azathioprine. The surgical treatment was open ileocaecal resection. Crohns disease activity index over time, expressed as area under the curve at 1, 3 and 5 years, was the primary endpoint. Subjective health measured with the 36-item Short Form Survey Instrument (SF36) and a visual analogue scale (VAS) were secondary endpoints. Results: There were no differences between the treatment groups in Crohns disease activity index over time. General health, measured as SF36 score, was higher in patients receiving surgical treatment than in those receiving medical treatment at 1 year, but there was no corresponding difference in VAS. Due to the slow inclusion rate and changes in clinical practice, the study was t = erminated prematurely. Conclusion: The study ended up being underpowered and should be interpreted with caution, but there was no clinically significant difference between the two treatment arms. Further studies are needed to address this important clinical question.
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| 10. |
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| 11. |
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| 12. |
- Gunnarsson, Rebeqa, et al.
(author)
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Mutation, methylation, and gene expression profiles in dup(1q)-positive pediatric B-cell precursor acute lymphoblastic leukemia
- 2018
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In: Leukemia. - : Springer Science and Business Media LLC. - 0887-6924 .- 1476-5551. ; 32:10, s. 2117-2125
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Journal article (peer-reviewed)abstract
- High-throughput sequencing was applied to investigate the mutation/methylation patterns on 1q and gene expression profiles in pediatric B-cell precursor acute lymphoblastic leukemia (BCP ALL) with/without (w/wo) dup(1q). Sequencing of the breakpoint regions and all exons on 1q in seven dup(1q)-positive cases revealed non-synonymous somatic single nucleotide variants (SNVs) in BLZF1, FMN2, KCNT2, LCE1C, NES, and PARP1. Deep sequencing of these in a validation cohort w (n = 17)/wo (n = 94) dup(1q) revealed similar SNV frequencies in the two groups (47% vs. 35%; P = 0.42). Only 0.6% of the 36,259 CpGs on 1q were differentially methylated between cases w (n = 14)/wo (n = 13) dup(1q). RNA sequencing of high hyperdiploid (HeH) and t(1;19)(q23;p13)-positive cases w (n = 14)/wo (n = 52) dup(1q) identified 252 and 424 differentially expressed genes, respectively; only seven overlapped. Of the overexpressed genes in the HeH and t(1;19) groups, 23 and 31%, respectively, mapped to 1q; 60-80% of these encode nucleic acid/protein binding factors or proteins with catalytic activity. We conclude that the pathogenetically important consequence of dup(1q) in BCP ALL is a gene-dosage effect, with the deregulated genes differing between genetic subtypes, but involving similar molecular functions, biological processes, and protein classes.
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| 13. |
- Härdelin, Linda, 1977, et al.
(author)
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Altered Thermal and Mechanical Properties of Spruce Galactoglucomannan Films Modified with an Etherification Reaction
- 2020
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 21:5, s. 1832-1840
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Journal article (peer-reviewed)abstract
- Native hemicellulose lacks many of the properties that make fossil fuel-based polymers excellent for use in today's industrial products and processes. The mechanical and thermal properties of the hemicellulose can, however, be modified, and its processability increased. We functionalized galactoglucomannan to lower its glass transition temperature (Tg) and thereby increase its processability. The functionalization was achieved through an etherification reaction with butyl glycidyl ether used at three molar ratios. Films were produced, and their mechanical and thermal properties were evaluated. Thermogravimetric analysis showed that increased substitution increased the degradation temperature and decreased the water content in the sample, implying increased hydrophobicity upon modification. Dynamic mechanical analysis indicated that butyl glycidyl ether functionalization alters the thermal properties of the modified films both in the absolute values of Tg and in the strength of the films. The etherification reaction resulted in a more ductile material than the unmodified galactoglucomannan (GGM).
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| 14. |
- Härdelin, Linda, 1977, et al.
(author)
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Hemicellulose foam
- 2014
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In: Proc Materials for Tomorrow. ; , s. Nr 24-
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Conference paper (other academic/artistic)
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| 15. |
- Härdelin, Linda, 1977, et al.
(author)
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Microcellular foaming of arabinoxylan and PEGylated arabinoxylan with supercritical CO2
- 2018
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 181, s. 442-449
-
Journal article (peer-reviewed)abstract
- In this study, arabinoxylan extracted from barley husks was reacted with polyethylene glycol (PEG) of various molecular weights to introduce an internal plasticizer into the polymer matrix. A successful PEGylation reaction was identified using FTIR and elemental analysis. Thermal and mechanical properties were studied using dynamic mechanical analysis, which revealed that the attachment of PEG chains reduced the glass transition temperature by up to 25 °C. Foaming experiments were conducted under different test conditions in a batch foaming process with supercritical CO 2 in a thermoregulated and pressurized cylinder. The foams were evaluated using SEM by studying the morphology of the samples foamed at different temperatures. The unmodified arabinoxylan sample was found to produce the best foam morphology, though the PEGylated samples could be produced at lower temperatures than could the unmodified arabinoxylan. This was interpreted as due to the decrease in the glass transition temperature.
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| 16. |
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| 17. |
- Johansson, Martin, 1986, et al.
(author)
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Experimental and Numerical Investigation of an Aerodynamically Loaded Guide Vane in a Turbine Duct
- 2011
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In: Proceedings of ASME TURBO EXPO 2011. Vancouver, 6-10 June 2011. - 9780791854679 ; 7:Paper no GT2011-46221, s. 831-840
-
Conference paper (peer-reviewed)abstract
- To obtain validation for an aerodynamically loaded guide vane in a turbine duct, a new configuration was implemented in the large-scale low-speed turbine rig facility at Chalmers University of Technology. The new configuration represents a modern counter rotating turbine design, with a flow turning structural vane. The flow in a turbine duct is very complex, due to the influence of the upstream turbine stage flow structures, and becomes even more complex if the turbine duct is equipped with an aerodynamically loaded structural vane. The flow has large secondary motions and is sensitive to flow separation, which is difficult to predict with numerical CFD methods. Very limited information is found in the open literature that can be used for validation of numerical methods. This paper presents the new experimental configuration and validation of its aerodynamic performance. Measurements including surface pressure, mapping of pressure losses and flow structures are presented and discussed. Comparison to initial CFD analyses enhance the understanding of the flow structures and gives a preliminary validation of used methods.
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| 18. |
- Jäger, Linda, et al.
(author)
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Increased survival with mechanical ventilation in post-tuberculosis patients with the combination of respiratory failure and chest wall deformity
- 2008
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In: Chest. - : Elsevier BV. - 1931-3543 .- 0012-3692. ; 133:1, s. 156-160
-
Journal article (peer-reviewed)abstract
- Background Patients who have suffered from tuberculosis are at risk of respiratory failure with hypercapnea from chest wall deformity and hypoxia from pulmonary sequelae. The combination of hypercapnea and hypoxia justifies both mechanical ventilation and oxygen therapy as treatment options. We aimed to study which treatment mode is associated with the best survival in patients with the combination of respiratory failure and chest wall deformity from tuberculosis. Methods Swedish patients starting oxygen therapy or mechanical ventilation between 1996 and 2004 due to the combination of respiratory failure and chest wall deformity from tuberculosis were eligible for conclusion. They were followed prospectively until October 2006, with death as the primary outcome. Results A cohort of 188 patients was included. Eighty-five received mechanical ventilation and 103 received oxygen therapy alone. No patients were excluded and none was lost to follow-up. Mechanical ventilation was associated with a significantly better survival than oxygen therapy alone, even after adjustments for age, gender, concomitant respiratory disease, blood gas tensions and vital capacity, with an adjusted hazard risk of death of 0.35 (95% CI 0.17-0.70). Conclusion Patients with the combination of respiratory failure and chest wall deformity from tuberculosis had a significantly better survival when treated with home mechanical ventilation than with long-term oxygen therapy alone. We recommend home mechanical ventilation with or without supplementary oxygen as the first choice of treatment for these patients.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Olsson, Linda, et al.
(author)
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Improved cytogenetic characterization and risk stratification of pediatric acute lymphoblastic leukemia using single nucleotide polymorphism array analysis : A single center experience of 296 cases
- 2018
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In: Genes Chromosomes and Cancer. - : Wiley. - 1045-2257 .- 1098-2264. ; 57:11, s. 604-607
-
Journal article (peer-reviewed)abstract
- Single nucleotide polymorphism array (SNP-A) analyses are increasingly being introduced in routine genetic diagnostics of acute lymphoblastic leukemia (ALL). Despite this, only few studies that have compared the diagnostic value of SNP-A with conventional chromosome banding have been published. We here report such a comparison of 296 ALL cases, the largest series to date. Only genomic imbalances >5 Mb and microdeletions targeting the BTG1, CDKN2A/B, EBF1, ERG, ETV6, IKZF1, PAX5, and RB1 genes and the pseudoautosomal region 1 (PAR1) were ascertained, in agreement with recent guidelines. Of 36 T-cell ALL cases, the karyotypes of 24 cases (67%) were revised by SNP-A analyses that either revealed additional imbalances >5 Mb or better characterized the changes found by G-banding. Of 260 B-cell precursor (BCP) ALL cases, SNP-A analyses identified additional copy number alterations, including the above-mentioned microdeletions, or better characterized the imbalances found by G-banding in 236 (91%) cases. Furthermore, the cytogenetic subtype classification of 41/260 (16%) BCP ALL cases was revised based on the SNP-A findings. Of the subtype revisions, 12/41 (29%) had clinical implications as regards risk stratifying cytogenetic groups or genotype-specific minimal residual disease stratification. We conclude that SNP-A analyses dramatically improve the cytogenetic characterization of both T-cell and BCP ALL and also provide important information pertinent to risk stratification of BCP ALL.
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| 25. |
- Rogers, David, et al.
(author)
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Highlights of Coastal Waves 1996
- 1998
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In: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 79, s. 1307-1326
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Journal article (peer-reviewed)
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| 26. |
- Ström, Linda, 1985
(author)
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Active sites and influence of reaction conditions on the selective catalytic reduction of NOx over the silver-alumina catalyst
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Hazardous nitrogen oxides (NOx) are challenging to remove from fuel-efficient excess-oxygen operating engines. A promising solution is selective catalytic reduction (SCR) of NOx, using hydrocarbons (HC-SCR) or ammonia (NH3-SCR) as reducing agent. Highly efficient SCR of NOx requires a fully understood system, which includes both the catalyst and the reducing agent. In this work, Ag/Al2O3 has been evaluated as an SCR catalyst with HC as well as NH3 as reducing agents, in order to investigate the active sites and elucidate the influence of the nature of the reducing agent during lean NOx reduction. In order to investigate the role of the active phase, Ag/Al2O3 was compared to an In/Al2O3 catalyst, containing the equivalent molar amount of active phase. In addition, the effect of an uneven distribution of the reducing agent is evaluated. Catalyst samples for which the active phase was synthesized in the water pools of a reversed microemulsion, using methanol as reducing agent for the metal complexes, was also prepared and evaluated. This work shows that the Ag/Al2O3 catalyst in general exhibits superior activity for NOx reduction compared to In/Al2O3. However, since one of the hydrocarbon reductants was shown to reduce NOx more efficiently over In/Al2O3, the exact nature of the reducing agent was shown to be of uttermost importance for the catalytic activity. In addition, the In/Al2O3 catalyst provides a higher concentration of acidic sites, compared to the Ag/Al2O3 catalyst, which was shown to inhibit the NH3-SCR reaction over this catalyst. Furthermore, it was confirmed that the active phase can be tailored in a microemulsion synthesis containing a greener route than used in the past, resulting in catalytically active nanoparticles. Moreover, the position of the reductant injection spray in the exhaust pipe in front of the SCR catalyst was shown to significantly affect the NOx reduction and unwanted slip of the reductant. The results presented in this thesis contribute to the overall understanding of the interplay between various active sites and reductants in SCR of NOx, and may therefore help advance current technologies to improve the sustainability of future transports.
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| 27. |
- Ström, Linda
(author)
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Effects of coastal forcing on turbulence and boundary-layer structure
- 1999
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Doctoral thesis (other academic/artistic)abstract
- Coastal mountains of significant elevation impose constraints for the surrounding flow. The aim of this study is to describe the modifications of the marine atmospheric boundary layer that occur offshore of the west coast of the United States. Aircraft measurements, up to 1000 km off the coast from two experiments, are used. This boundary layer is capped by a subsidence inversion, which slopes down toward the coast and produces large thermal winds. Low-level wind maxima (i.e. jets) are typical for these conditions, commonly a 40-50% increase relative to the 30 m wind speed. The effects of coastal forcing on low-level winds cancel in average when no regard is taken for position relative a cape or point. The variability of the low-level wind speed increases nevertheless significantly toward the coast, the standard deviation is ±40% of the offshore value. The scale of the adjustment downstream of a cape or point is specifically addressed. Some measurements support a formulation of the coastal extent based on an inviscid shallow-water concept; mean variables (i.e. 30 m wind speed and boundary-layer depth) and turbulent parameters (i.e. dissipation and shear production of turbulent kinetic energy) vary in a uniform, predicted manner. The effects of coastal forcing on winds result in cold sea surface temperatures at the coast, due to upwelling. Stability becomes a function of offshore distance. Surface-layer turbulence statistics and spectra (and cospectra) of turbulence variables are presented. Across- and along-wind sampled spectra (and cospectra) show that large wind shear and shallow boundary layer affect the scales of the turbulence eddies. The relation between the standard deviations of wind components are affected. The turbulence appears to be non-local in some aspects, entrainment fluxes are proposed to be important due to a shallow boundary layer with a sharp, sloping inversion and a low-level jet.
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| 28. |
- Ström, Linda, 1985, et al.
(author)
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Hydrogen-assisted SCR of NOx over alumina-supported silver and indium catalysts using C2-hydrocarbons and oxygenates
- 2016
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In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 181, s. 403-412
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Journal article (peer-reviewed)abstract
- This work focuses on the selective catalytic reduction (SCR) of nitrogen oxides (NOx) with ethane, ethene, acetic acid, dimethyl ether (DME) and ethanol, respectively, over alumina-supported silver and indium catalysts. The impact of hydrogen and the nature of the reductant on the catalyst structure and SCR activity are studied. The ability to reduce NOx differs significantly among the studied reductants, but also between the two catalysts, of which Ag/Al2O3 is the overall most active catalyst. However, the In/Al2O3 catalyst exhibits high SCR activity with DME as reductant in contrast to the Ag/Al2O3 catalyst, which shows negligible activity. We attribute this difference to the higher number of acidic sites on the In/Al2O3 catalyst and the higher degree of DME combustion over Ag/Al2O3. Moreover, the number of sites that previously have been identified to promote hydrocarbon activation, i.e. silver cluster sites (Agnδ+) in Ag/Al2O3 catalysts and indium cluster sites (In3+) in In/Al2O3 catalysts, are shown to increase upon addition of small amounts of hydrogen in the feed. We suggest that the increased SCR activity over In/Al2O3 originates from an increased number of sites for activation of hydrocarbons, analogous to previous proposals for Ag-based catalysts, in combination with a direct effect on the reaction mechanism.
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| 29. |
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| 30. |
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| 31. |
- Ström, Linda, 1985
(author)
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Selective Catalytic Reduction of NOx over Alumina-Supported Silver and Indium During Lean Operation
- 2016
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Licentiate thesis (other academic/artistic)abstract
- Catalytic emission control for vehicles was first applied in the 1970’s. The first such catalysts were designed to oxidize unburned hydrocarbons (HC) and carbon monoxide (CO). A few years later, the oxidation catalyst was further developed into the three-way catalyst (TWC), which efficiently removes CO, HC and nitrogen oxides (NOx under stoichiometric air-to-fuel ratios. However, the awareness of climate changes, caused by anthropogenic emissions of carbon dioxide (CO2), is a major motivator for the development of fuel-efficient engines, operating in excess oxygen (lean) combustion. At these air-to-fuel ratios, the TWC is ineffective for NOx reduction, promoting the development of lean NOx reduction techniques. Among the most promising today is selective catalytic reduction (SCR), for which the silver-alumina (Ag/Al2O3) catalyst shows promising results, both with HC and ammonia (NH3), as the reducing agent. The current work focuses on the nature of the active sites of the Ag/Al2O3 catalyst and the impact of the structure of the reductant on the selective catalytic reduction of NOx. For this purpose, five different hydrocarbons and oxygenates, all containing two carbon atoms in the structure, as well as NH3, are investigated as reducing agents, with and without the presence of hydrogen. Furthermore, the influence of the active phase is elucidated by exchanging silver for the equivalent molar amount of indium. The catalysts are prepared by incipient wetness impregnation, characterized with regard to specific surface area, crystalline structure, concentration and strength of acidic sites, SCR activity and surface species. The latter are studied by diffuse reflectance ultraviolet-visible (UV-vis) spectroscopy, where spectra from both the fresh samples and from samples subjected to various gas-phase pretreatments, mimicking conditions of the SCR reaction environment, are recorded. The connection between the silver and indium species, and the gas-phase environment is discussed, and it is proposed that species important for the activation of the reducing agent are essential for high SCR activity, both during HC- and NH3-SCR. Furthermore, quantification of the NO reduction and NH3 slip over Ag/Al2O3 is performed for different locations of the reductant injection spray. The probability of a stoichiometric ammonia dose is higher when the spray is positioned in the center of the exhaust pipe, compared to at the pipe wall. Moreover, the NO conversion increases rapidly with increasing ammonia dose, however, NH3 doses of several times the stoichiometric amount do not improve NO reduction significantly but increase the NH3 slip almost linearly.
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| 32. |
- Ström, Linda, 1985, et al.
(author)
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Surface species and metal oxidation state during H2‐assisted NH3‐SCR of NOx over alumina‐supported silver and indium
- 2018
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In: Catalysts. - : MDPI AG. - 2073-4344. ; 8:1
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Journal article (peer-reviewed)abstract
- Alumina‐supported silver and indium catalysts are investigated for the hydrogen‐assisted selective catalytic reduction (SCR) of NO x with ammonia. Particularly, we focus on the active phase of the catalyst and the formation of surface species, as a function of the gas environment. Diffuse reflectance ultraviolet‐visible (UV‐vis) spectroscopy was used to follow the oxidation state of the silver and indium phases, and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to elucidate the formation of surface species during SCR conditions. In addition, the NO x reduction efficiency of the materials was evaluated using H 2 ‐assisted NH 3 ‐SCR. The DRIFTS results show that the Ag/Al 2 O 3 sample forms NO‐containing surface species during SCR conditions to a higher extent compared to the In/Al 2 O 3 sample. The silver sample also appears to be more reduced by H 2 than the indium sample, as revealed by UV‐vis spectroscopic experiments. Addition of H 2 , however, may promote the formation of highly dispersed In 2 O 3 clusters, which previously have been suggested to be important for the SCR reaction. The affinity to adsorb NH 3 is confirmed by both temperature programmed desorption (NH 3 ‐TPD) and in situ DRIFTS to be higher for the In/Al 2 O 3 sample compared to Ag/Al 2 O 3 . The strong adsorption of NH 3 may inhibit (self‐poison) the NH 3 activation, thereby hindering further reaction over this catalyst, which is also shown by the lower SCR activity compared to Ag/Al 2 O 3 .
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| 33. |
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| 34. |
- von Rosen, Philip, et al.
(author)
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Offered Support and Knowledge about the Menstrual Cycle in the Athletic Community: A Cross-Sectional Study of 1086 Female Athletes
- 2022
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In: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 19:19
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Journal article (peer-reviewed)abstract
- Many female athletes perceive that symptoms related to the menstrual cycle such as dysmenorrhea, premenstrual symptoms, amenorrhea or side-effects of hormonal contraceptives negatively impact their training, performance, and general well-being. Knowledge and communication about female athletes’ health is therefore important in the sport community. The aims of this study were to explore the level of knowledge and communication about menstrual cycle issues and use of hormonal contraceptives in the athletic community and to describe the kinds of medical support offered to female athletes. A total of 1086 Swedish and Norwegian athletes from 57 different sports responded to a web-based questionnaire. Of these, 58% (n = 627) practiced team sports and 42% (n = 459) individual sports. Twenty-six percent (n = 278) of the athletes perceived their knowledge about female athlete health to be poor/very poor and the knowledge was most often acquired from medical staff. Fifty-three percent (n = 572) of the athletes perceived the knowledge acquired of their coaches as poor/very poor, even though a significantly (p < 0.001) higher proportion of athletes with a female coach (30%, n = 31) rated their coach’s knowledge as very good/good, compared to athletes with a male coach (5%, n = 31). Only 11% (n = 116) of the athletes discussed female health issues with their coach. The majority (81%, n = 842) of the athletes partly to strongly agreed that female athlete health is considered a taboo topic in the athletic community. Forty-seven percent (n = 510) of the athletes had access to a physiotherapist, while only three percent (n = 29) had access to a gynecologist. Low perceived knowledge, lack of communication and support demonstrate the need for a multi-professional medical team and enhanced educational efforts focused on female athlete health in the athletic community.
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