| 1. |
- Abugabbara, Marwan, et al.
(author)
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How to develop fifth-generation district heating and cooling in Sweden? : Application review and best practices proposed by middle agents
- 2023
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In: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 9, s. 4971-4983
-
Journal article (peer-reviewed)abstract
- Sweden has an ambitious plan to fully decarbonise district heating by 2030 and to contribute with negative emissions of greenhouse gases in 2050. The vagaries of the energy market associated with climate, political, and social changes entail cross-sectoral integration that can fulfill these national targets. Fifth-generation district heating and cooling (5GDHC) is a relatively new concept of district energy systems that features a simultaneous supply of heating and cooling using power-to-heat technologies. This paper presents best practices for developing 5GDHC systems in Sweden to reach a consensus view on these systems among all stakeholders. A mixed-method combining best practice and roadmapping workshops has been used to disseminate mixed knowledge and experience from middle agents representing industry professionals and practitioners. Four successful implementations of 5GDHC systems are demonstrated and the important learned lessons are shared. The best practices are outlined for system planning, system modeling and simulation, prevailing business models for energy communities, and system monitoring. A roadmap from the middle agents’ point of view is composed and can be utilised to establish industry standards and common regulatory frameworks. © 2023 The Author(s)
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| 2. |
- Andersson, Cecilia, et al.
(author)
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Mice Lacking 12/15-Lipoxygenase have Attenuated Airway Allergic Inflammation and Remodeling.
- 2008
-
In: American Journal of Respiratory Cell and Molecular Biology. - 1535-4989. ; 39:6, s. 648-656
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Journal article (peer-reviewed)abstract
- Arachidonate 15-lipoxygenase (LO)-1 has been implicated in allergic inflammation and asthma. The overall effect of 15-LO in allergic inflammation in vivo is, however, unclear. This study investigates systemic allergen sensitization and local allergic airway inflammation and remodeling in mice lacking the murine 12/15-LO, the ortholog to human 15-LO-1. Upon systemic sensitization with intraperitoneal ovalbumin, 12/15 LO(-/-) mice produced elevated levels of allergen-specific IgE compared to wild type (Wt) controls. However, when challenged with repeated aerosolized allergen sensitized 12/15 LO(-/-) mice had an impaired development of airway allergic inflammation compared to Wt controls, as indicated by reduced BAL fluid leukocytes (eosinophils, lymphocytes macrophages) and Th2 cytokines (IL-4, IL-5, IL-13) as well as tissue eosinophils. Allergen-induced airway epithelial proliferation was also significantly attenuated in 12/15 LO(-/-) mice whereas goblet cell hyperplasia was unaffected. However, 12/15 LO(-/-) mice had significantly reduced luminal mucus secretions compared to Wt controls. The repeated allergen challenges resulted in a dramatic increase of alpha-smooth muscle-actin positive alveolar cells in the peripheral airways, a phenomenon that was significantly less developed in 12/15 LO(-/-) mice. In conclusion, our data suggest that 12/15 LO(-/-) mice, although having a fully developed systemic sensitization, did not establish a fully developed allergic airway inflammation and associated manifestations of central and peripheral airway remodeling. These data suggest that 12/15-LO derived metabolites play an important pathophysiological role in allergen-induced inflammation and remodeling. Hence, pharmacologic targeting of the human 15-LO-1 may represent an attractive therapeutic strategy to control inflammation and remodeling in asthma.
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| 3. |
- Bernhold Brechter, Anna, 1971-
(author)
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Kinins : important regulators in inflammation induced bone resorption
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Inflammatory processes in, or in close vicinity of, the skeleton often lead to loss of bone tissue. Different cytokines have been shown to be involved as stimulators of inflammatory induced osteoclastic bone resorption. During inflammatory processes also the kallikrein-kinin system is activated, leading to production of kinins that can cause pain, vasodilation and increased permeability of vessels. Kinins can also induce bone resorption in vitro. All cytokines and kinins that stimulate bone resorption stimulate in parallell prostaglandin synthesis, and prostaglandins, per se, have also been shown to induce bone resorption. The aim of this project was to increase the knowledge about the mechanisms involved in the interactions between different inflammatory mediators (i.e. kinins, cytokines and prostaglandins) suggested to be involved in the pathogenesis of inflammatory bone resorbing diseases. Human osteoblasts (MG-63) are equipped with both kinin B1 and B2 receptors linked to prostaglandin release and the stimulation of prostaglandin release are likely mediated via separate molecular mechanisms (Paper I). Activation of B1 or B2 receptors causes synergistic stimulation of PGE2 synthesis induced by either interleukin-1b (IL-1b) or tumour necrosis factor-a (TNF-a) (Paper II). The molecular mechanism involves increased expression of cyclooxygenase-2 (COX-2) and results in synergistic potentiation of receptor activator of NF-kB ligand (RANKL) protein expression. The synergistic interaction is dependent on the activation of NF-kB and the mitogen-activated protein kinases (MAPK) p38 and JNK (Paper II). The synergistic increase in RANKL expression might be an explanation why kinins potentiate IL-1b induced bone resorption, a mechanism likely to be important in inflammation induced bone resorption in diseases such as periodontal disease and rheumatoid arthritis. The synergism between kinins and IL-1b or TNF-a might also be dependent on regulation of kinin receptors, since both IL-1b and TNF-a markedly upregulated B1 and B2 receptors, both at the mRNA level and protein level (Paper III). This upregulation is not further potentiated by the kinins, and different kinin receptor agonists do not regulate the receptors for IL-1b or TNF-a, in MG-63 cells. No other cytokines known to stimulate bone resorption regulates the expressions of B1 and B2 receptors. The IL-1b- or TNF-a-induced enhancements of B1 and B2 receptor expressions involve activation of NF-kB and MAPK. The enhancement of kinin receptors may also be an important mechanism in the synergistic interactions between the two pro-inflammatory cytokines and kinins (paper III). IL-4 and IL-13 are two cytokines that have been shown to inhibit bone resorption. We have shown that COX-2 and both B1 and B2 receptors are down-regulated by IL-4 and IL-13, via a ‘signal transducer and activator of transcription6’ (STAT6) dependent pathway, which might be an important regulatory mechanism in inflammation induced bone resorption (paper IV). In conclusion, the mechanisms behind the synergistic potentiation of prostaglandin formation and increased bone resorption caused by co-stimulation with kinins and IL-1b or TNF-a seem to involve both potentiation of COX-2 and subsequently increased levels of RANKL, as well as upregulation of B1 and B2 kinin receptors. Interestingly, IL-4 and IL-13 decreased the expressions of COX-2 and both B1 and B2 receptors. These events might be important in the regulation of inflammation induced bone resorption in diseases such as periodontitis and rheumatoid arthritis.
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| 4. |
- Blomgren, Charlotte, et al.
(author)
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Long-term performance of instrumental activities of daily living in young and middle-aged stroke survivors-Impact of cognitive dysfunction, emotional problems and fatigue.
- 2019
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In: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 14:5
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Journal article (peer-reviewed)abstract
- With an upward trend in the number of people who return home to independent living after stroke, the ability to perform more complex activities is becoming an increasingly important long-term outcome after stroke. Although associations between Instrumental Activities of Daily Living (IADL) and cognitive dysfunction, emotional problems, and fatigue have been reported, less is known about the long-term impact of these stroke consequences on the performance of everyday activities in young and middle-aged stroke survivors.To explore the impact of cognitive dysfunction, emotional problems, and fatigue on long-term performance of instrumental activities of daily living in young and middle-aged stroke survivors.Data on stroke survivors, aged 18-69 at index stroke, were collected from the Sahlgrenska Academy Study on Ischaemic Stroke. IADL outcome was assessed using the Frenchay Activities Index (FAI), and the impact of chosen variables was assessed using Spearman´s rank-order correlation and logistic regression.Seven years after index stroke, 296 stroke survivors (median age of 64) were included in this study. Cognitive dysfunction showed the strongest correlations with FAI outcome and independently explained worse outcome on FAI summary score and the domain of work/leisure activities. Fatigue was independently explanatory of worse outcome on FAI summary score and domestic chores, while depressive symptoms independently explained worse outcome on work/leisure activities. In a subgroup with only those participants who had no or minimal residual neurological deficits at follow-up (NIHSS score 0), cognitive dysfunction independently explained worse outcome on FAI summary score and work/leisure activities. Depressive symptoms independently explained worse outcome on FAI summary score and domestic chores.Our results show that in young and middle-aged stroke survivors, cognitive dysfunction, depressive symptoms, and fatigue negatively impact performance of IADL even at seven years post stroke onset. Further, we have shown that an impact of both cognitive dysfunction and depressive symptoms can be found also among stroke survivors with mild or no remaining neurological deficits.
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| 5. |
- Broeren, Jurgen, et al.
(author)
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Virtual rehabilitation after stroke.
- 2008
-
In: Studies in health technology and informatics. - 0926-9630 .- 1879-8365. ; 136, s. 77-82
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Journal article (peer-reviewed)abstract
- The purpose of this project was to investigate the effects of Virtual Reality technology and haptics for stroke rehabilitation. Twenty-nine stroke subjects, 17 women, and 12 men aged 44-85 years, participated in three different studies. All participants responded favorable to the use of the VR activity station. A change of attitude took place after the subjects were exposed to playing computer games. The general experience with the VR application approach suggests that this treatment concept is promising in stroke rehabilitation, with a wide range of applicability.
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| 6. |
- Brunnström, Åsa, et al.
(author)
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Biosynthesis of 14,15-Hepoxilins in Human L1236 Hodgkin Lymphoma Cells and Eosinophils
- 2011
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In: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 46:1, s. 69-79
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Journal article (peer-reviewed)abstract
- Hepoxilins are epoxy alcohols synthesized through the 12-lipoxygenase (12-LO) pathway in animal cells. The epidermis is the principal source of hepoxilins in humans. Here we report on the formation of novel hepoxilin regioisomers formed by the 15-LO pathway in human cells. The Hodgkin lymphoma cell line L1236 possesses high 15-lipoxygenase-1 (15-LO-1) activity and incubation of L1236 cells with arachidonic acid led to the formation of 11(S)-hydroxy-14(S),15(S)-epoxy 5(Z),8(Z),12(E) eicosatrienoic acid (14,15-HxA(3) 11(S)) and 13(R)-hydroxy-14(S),15(S)-epoxy 5(Z),8(Z),11(Z) eicosatrienoic acid (14,15-HxB(3) 13 (R)). In addition, two hitherto unidentified products were detected and these products were collected and analyzed by positive ion electrospray tandem mass spectrometry. These metabolites were identified as 11(S),15(S)-dihydroxy-14(R)-glutathionyl-5(Z),8(Z),12(E)-eicosatrienoic acid (14,15-HxA(3)-C) and 11(S),15(S)-dihydroxy-14(R)-cysteinyl-glycyl-5(Z),8(Z),12(E)-eicosatrien oic acid (14,15-HxA(3)-D). Incubation of L1236 cells with synthetic 14,15-HxA(3) 11(S) also led to the formation of 14,15-HxA(3)-C and 14,15-HxA(3)-D. Several soluble glutathione transferases, in particular GST M1-1 and GST P1-1, were found to catalyze the conversion of 14,15-HxA(3) to 14,15-HxA(3)-C. L1236 cells produced approximately twice as much eoxins as cysteinyl-containing hepoxilins upon stimulation with arachidonic acid. Human eosinophils, nasal polyps and dendritic cells selectively formed 14,15-HxA(3) 11(S) and 14,15-HxB(3) 13(R) stereoisomers, but not cysteinyl-containing hepoxilins, after stimulation with arachidonic acid. Furthermore, purified recombinant 15-LO-1 alone catalyzed the conversion of arachidonic acid to 14,15-HxA(3) 11(S) and 14,15-HxB(3) 13(R), showing that human 15-LO-1 possesses intrinsic 14,15-hepoxilin synthase activity.
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| 7. |
- Brunnström, Åsa, et al.
(author)
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On the biosynthesis of 15-HETE and eoxin C-4 by human airway epithelial cells
- 2015
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In: Prostaglandins & other lipid mediators. - : Elsevier BV. - 1098-8823 .- 2212-196X. ; 121, s. 83-90
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Journal article (peer-reviewed)abstract
- Several lines of evidence indicate that 15-lipoxygenase type 1 (15-LO-1) plays a pathophysiological role in asthma. The aim for this study was to investigate the 15-LO-1 expression and activity in primary human airway epithelial cells cultivated on micro-porous filters at air liquid interface. Incubation of human airway epithelial cells with arachidonic acid led to the formation of 15(S)-hydroxy-eicosatetraenoic acid (15-HETE) and exposing the cells to bacteria or physical injury markedly increased their production of 15-HETE. The cells were also found to convert arachidonic acid to eoxin C-4 (EXC4). Subcellular fractionation revealed that the conversion of EXA(4) to EXC4 was catalyzed by a soluble glutathione transferase (GST). The GST P1-1 enzyme was found to possess the highest activity of the investigated soluble GSTs. Following IL-4 treatment of airway epithelial cells, microarray analysis confirmed high expression of 15-LO-1 and GST P1-1, and immunohistochemical staining of bronchial biopsies revealed co-localization of 15-LO-1 and GST P1-1 in airway epithelial cells. These results indicate that respiratory infection and cell injury may activate the 15-LO pathway in airway epithelial cells. Furthermore, we also demonstrate that airway epithelial cells have the capacity to produce EXC4.
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| 8. |
- Carvalho, Ricardo F S, et al.
(author)
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Expression of mast cell tryptases in Hodgkin and Reed-Sternberg (HRS) cells
- 2008
-
In: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 67:1, s. 53-56
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Journal article (peer-reviewed)abstract
- Tryptase is the most abundant protease in human mast cells, and is often used as a marker for the enumeration of mast cells in tissue. Here we report that tumour cells from Hodgkin lymphoma, the so called Hodgkin and Reed-Sternberg cells, can express tryptase. Hodgkin lymphoma cell lines expressed mRNA for both alpha- and beta-tryptase and also produced the protein, although at much lower concentrations than mast cells. However, the frequency of tryptase positive HRS-cells in situ was very low. This report demonstrates that tumour cells of lymphoid origin can express tryptase in vitro and in situ.
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| 9. |
- Cehlin, Mathias, Doktor, 1974-, et al.
(author)
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Urban Morphology and City Ventilation
- 2020
-
Conference paper (peer-reviewed)abstract
- The purpose of the paper is to examine the relation between urban morphology, wind direction and air flow rates. In the study a highly idealized city model was used consisting of a circular block divided into two or four equally large sectors. Wind tunnel experiments and CFD predictions have been conducted. The interaction between the atmospheric boundary layer and a city is considered to be both a function of the overall shape and the internal resistance to the flow caused by the friction when the wind flows over the urban surfaces. Flow along the streets is generated by pressure differences. In the wind tunnel, velocity measurements have been recorded in the streets at several points and pressure on the ground was registered in 400 points. The wind tunnel measurements were used to validate the CFD model. The CFD predictions provided complete flow and pressure fields for different configurations and wind directions. The flow balance is presented considering both the horizontal air flow and the vertical air flow (subsidence and updraft). Special attention was on the pressure distribution at ground level (pressure footprint), which is believed to provide valuable information that can be used for qualitative city ventilation analyses.
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| 10. |
- Chen, Lan, et al.
(author)
-
The impacts of building height variations and building packing densities on flow adjustment and city breathability in idealized urban models
- 2017
-
In: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 118, s. 344-361
-
Journal article (peer-reviewed)abstract
- Improving city breathability has been confirmed as one feasible measure to improve pollutant dilution in the urban canopy layer (UCL). Building height variability enhances vertical mixing, but its impacts remain not completely explored. Therefore, both wind tunnel experiments and computational fluid dynamic (CFD) simulations are used to investigate the effect of building height variations (six height standard deviations σH = 0%–77.8%) associated to building packing densities namely λp/λf = 0.25/0.375 (medium-density) and 0.44/0.67 (compact) on city breathability. Two bulk variables (i.e. the in-canopy velocity (UC) and exchange velocity (UE)) are adopted to quantify the horizontal and vertical city breathability respectively, which are normalized by the reference velocity (Uref) in the free flow, typically set at z = 2.5H0 where H0 is the mean building height. Both flow quantities and city breathability experience a flow adjustment process, then reach a balance. The adjustment distance is at least three times longer than four rows documented in previous literature. The medium-density arrays experience much larger UC and UE than the compact ones. UE is found mainly induced by vertical turbulent fluxes, instead of vertical mean flows. In height-variation cases, taller buildings experience larger drag force and city breathability than lower buildings and those in uniform-height cases. For medium-density and compact models with uniform height, the balanced UC/Uref are 0.124 and 0.105 respectively, moreover the balanced UE/Uref are 0.0078 and 0.0065. In contrast, the average UC/Uref in height-variation cases are larger (115.3%–139.5% and 125.7%–141.9% of uniform-height cases) but UE/Uref are smaller (74.4%–79.5% and 61.5%–86.2% of uniform-height cases) for medium-density and compact models.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Claesson, Carina, 1970-, et al.
(author)
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Molecular typing and detection of the aap and atlE genes and ica operon in multi-drug resistant and susceptible coagulase negative staphylococci
-
Other publication (other academic/artistic)abstract
- The aims of the present study were to identify clinical isolates of multidrug resistant (MDR) and susceptible coagulase negative staphylococci (CoNS), (n=76) to the species level by rpoB amplicon sequencing and to detect and compare the presence of the atlE and aap genes and the ica operon between MDR (n=26) and susceptible (n=27) Staphylococcus epidermidis isolates. Detection of the atlE and aap genes and ica operon was carried out using PCR amplification. Most of the isolates were S. epidermidis, both among the MDR and susceptible CoNS. Staphylococcus haemolyticus was the only other species found in the MDR group. All MDR and 96% of the susceptible S. epidermidis isolates carried the atlE gene. The ica operon was present in about 30% of both the MDR and susceptible S. epidermidis isolates. By comparison, aap gene carriage was more common among susceptible S. epidermidis isolates (44%) than the MDR S. epidermidis isolates (27%). The atlE gene was the only gene that was found alone in the S. epidermidis genome. About 25% of the S. epidermidis isolates carried the atlE and aap genes and the ica operon simultaneously. In conclusion, rpoB gene amplicon sequencing is an easy and reliable method to identify CoNS isolates at the species and subspecies level. Both MDR and susceptible S. epidermidis isolates were found to be well equipped with adhesion and aggregation genes which might help them to adhere to artificial surfaces, colonize hospitalised patients and cause biofilm-related infections.
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| 15. |
- Claesson, Carina, 1970-
(author)
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Staphylococci and Enterococci : Studies on activity of antimicrobial agents and detection of genes involved in biofilm formation
- 2010
-
Doctoral thesis (other academic/artistic)abstract
- The Gram-positive cocci, Staphylococcus aureus, coagulase negative staphylococci (CoNS), Enterococcus faecalis and Enterococcus faecium, are the bacteria most often isolated from patients with hospital acquired infections. S. aureus is one of the most important pathogens and have a variety of virulence mechanisms which help it to infect the patient and cause tissue damage. CoNS and enterococci are low virulent bacteria and predominantly cause infections in individuals with underlying illness, individuals that have undergone surgery or with suppressed immune-system. The aims of this thesis were i) to investigate the susceptibility to different antimicrobial agents among S. aureus, CoNS, E. faecium and E. faecalis isolates from primary care centres, general hospital wards and intensive care units in Denmark, Finland, Norway and Sweden and ii) to study the prevalence of the cytolysin genes and genes involved in biofilm formation among CoNS, E. faecium and E. faecalis. The results in this thesis show that the resistance rates among S. aureus and E. faecalis is still rather low in the north European countries. Among CoNS and E. faecium resistance rates are higher and comparable with rates in other European countries and US. CoNS had statistically significant differences in susceptibility rates between the ward levels with the lower susceptibility rates found at ICUs. Continued surveillance of resistance rates to antimicrobial agents among both staphylococci and enterococci are important internationally, nationally and locally. The results in this thesis also show that all multidrug resistant and 96% of the susceptible CoNS isolates carried at least one of the atlE and aap genes or the ica operon. Among E. faecalis isolates with HLGR, belonging to a cluster of genetically related isolates, both the esp and asa1 genes were carried in a high degree while the cyl operon was less frequently found. In addition, about 30% of unique E. faecalis isolates carried two or more of the virulence genes. Among E. faecium isolates the esp gene was common but asa1 and the cyl operon was not found in any of the isolates. Both CoNS and E. faecalis isolates from hospitalised patients are well equipped with genes involved in biofilm formation. These genes, when expressed and even more in combination with resistance to antimicrobial agents, might give these isolates an advantage compared to other isolates when it comes to adhesion to artificial surfaces, persistence in the hospital environment, colonisation of hospitalised patients and to cause nosocomial infections. Further studies are needed to be able to determine which isolates that causes hospital acquired infections and to evaluate the importance of the genes involved in biofilm formation as virulence factors and about how to prevent biofilm related infections from emerging
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| 16. |
- Claesson, Erik, et al.
(author)
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Carbide Precipitation during Processing of Two Low-Alloyed Martensitic Tool Steels with 0.11 and 0.17 V/Mo Ratios Studied by Neutron Scattering, Electron Microscopy and Atom Probe
- 2022
-
In: Metals. - Basel, Switzerland : MDPI AG. - 2075-4701. ; 12:5
-
Journal article (peer-reviewed)abstract
- Two industrially processed low-alloyed martensitic tool steel alloys with compositions Fe-0.3C-1.1Si-0.81Mn-1.5Cr-1.4Ni-1.1Mo-0.13V and Fe-0.3C-1.1Si-0.81Mn-1.4Cr-0.7Ni-0.8Mo-0.14V (wt.%) were characterized using small-angle neutron scattering (SANS), scanning electron microscopy (SEM), Scanning transmission electron microscopy (STEM), and atom probe tomography (APT). The combination of methods enables an understanding of the complex precipitation sequences that occur in these materials during the processing. Nb-rich primary carbides form at hot working, while Fe-rich auto-tempering carbides precipitate upon quenching, and cementite carbides grow during tempering when Mo-rich secondary carbides also nucleate and grow. The number density of Mo-rich carbides increases with tempering time, and after 24 h, it is two to three orders of magnitude higher than the Fe-rich carbides. A high number density of Mo-rich carbides is important to strengthen these low-alloyed tool steels through precipitation hardening. The results indicate that the Mo-rich secondary carbide precipitates are initially of MC character, whilst later they start to appear as M2C. This change of the secondary carbides is diffusion driven and is therefore mainly seen for longer tempering times at the higher tempering temperature of 600◦C.
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| 17. |
- Claesson, Erik, 1988-
(author)
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Carbides in martensitic medium carbon low alloyed tool steels studied with small angle scattering techniques, electron microscopy and atom probe tomography
- 2023
-
Doctoral thesis (other academic/artistic)abstract
- Medium carbon low alloyed tool steels are used today in various areas to shape plastics, nonferrous metals, and steels, and they are crucial in the manufacturing industry. To be effective, tool steels must be strong and tough, and have high wear resistance and temperature stability. To achievethe desired properties, materials are alloyed so that secondary phaseparticles precipitate during processing, especially during the tempering of martensitic steels. However, the hardening contribution relates to the size,volume fraction and number density of precipitates, controlled by alloy composition and heat-treating parameters. It is therefore essential to understand how, where, and when the particles nucleate and how the precipitation sequence and kinetics are affected by alloying additions,tempering temperature, and time.This work is aimed to study carbide precipitation in two commercial low-alloy tool steel using small-angle neutron and X-ray scattering. To support these methods, samples were characterized with transmission electronmicroscopy (TEM) and atom probe tomography (APT). With a combination of high-resolution techniques, it was possible to establish the precipitation sequence in these steels. It was also possible with various small angle scattering techniques to determine the evolution of volume fraction and number density of precipitates as a function of tempering parameters.First, small angle neutron scattering (SANS) was used, which is an excellent method for bulk quantification of small precipitates in steel. It was possible with SANS to broadly study the precipitation process depending on annealing temperature and time. However, it is difficult with regular small angle scattering (SAS) to distinguish particle types with overlapping size distributions. To possibly separate the scattering signal from different carbide types, measurements were carried out with polarized small angle neutron scattering (SANSPOL) and anomalous small-angle X-ray scattering(ASAXS). With ASAXS it was possible to isolate the signal from molybdenum-rich carbides from other types of carbides.With SANSPOL, it was possible to follow the enrichment of alloy elements in cementite. The appearance of cementite can be described as an iron-richcore with a chromium-enriched shell. The partitioning of substitutional elements affects the stability of cementite and the alloy carbides. It was also possible with SANSPOL, during heating, to follow the initial precipitation of particles.Results from different experimental methods have been compared with precipitation simulations using thermodynamics-based precipitationmodeling. Equilibrium calculations indicates the possible stability ofdifferent precipitates, and the kinetics are captured with tools such as TCPRISMA to simulate structure evolution during tempering. Hardness measurements were made to correlate structure evolution to mechanical properties.
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| 18. |
- Claesson, Erik, et al.
(author)
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Early precipitation behavior of secondary carbides in medium carbon low alloyed tool steel studied by in-situ polarized small-angle scattering and precipitation modelling
-
Journal article (peer-reviewed)abstract
- The strength of tempered martensite in low alloyed tool steel depends on the precipitation of secondary carbides. Tempering parameters such as time and temperature together with heating rate to tempering temperature will influence the precipitation sequence and these critical process parameters must be controlled to achieve ultimate precipitation strengthening. In this work precipitation was studied in a low alloyed tool steel using in-situ polarized small angle scattering (SANSPOL) during heating and isothermal holding. It was possible with SANSPOL to study the initial precipitation of secondary Mo- and V-rich carbides. It was found that Mo- and V-rich carbides form above 500 °C, simultaneously to the formation of cementite, which started to form already at lower temperature. It was furthermore found that the cementite particles can be described as having a core-shell structure, the Mo-V-rich carbides small and were approximated as spherical. Precipitation simulations performed using TC-PRSIMA were finally performed to compare with the experimental results, and the simulations were found to describe the experimental results well.
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| 19. |
- Claesson, Erik, et al.
(author)
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Evolution of iron carbides during tempering of low-alloy tool steel studied with polarized small angle neutron scattering, electron microscopy and atom probe
- 2022
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In: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 194, s. 112464-112464
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Journal article (peer-reviewed)abstract
- The magnetic scattering of iron carbides in low-alloy tool steel was investigated ex-situ by polarized small angle neutron scattering measurements after tempering the steel at 550 °C and 600 °C. Magnetic features could be detected in the as-quenched sample resulting in a negative interference term, believed to be either θ-Fe3C, η-Fe2C, or ε-Fe2-3C. During tempering the evolution of cementite could be studied by the variation of the interference term and in γ-ratio, which is the ratio of the magnetic to nuclear scattering length density contrast. From scanning transmission electron microscopy (STEM) and atom probe tomography, it is evident that cementite (θ-Fe3C) is present directly when reaching the tempering temperature of either 550 °C or 600 °C. At longer tempering times, cementite gets enriched with substitutional elements like chromium and manganese, forming an enriched shell on the cementite particles. STEM and energy dispersive x-ray spectrometry show that the chemical composition of small cementite particles approaches that of Cr-rich M7C3 carbides after 24 h at 600 °C. It is also seen that small non-magnetic particles precipitate during tempering and these correspond well with molybdenum and vanadium-rich carbides.
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| 20. |
- Claesson, Erik, et al.
(author)
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Mapping of the carbide precipitation sequence and the in-situ transformation of cementite in medium carbon low alloyed tool steel with Scanning Precession Electron Diffraction
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Journal article (other academic/artistic)abstract
- Precipitation of carbides after tempering at 600 °C of a medium carbon low alloyed tool steel was studied with scanning precession electron diffraction (SPED). The precipitation sequence was evaluated by mapping the carbide distribution on carbon extraction replicas. This gave detailed information about formed precipitates which could be identified based on electron diffraction. The experimental work was compared to equilibrium calculations and energy dispersive x-ray spectroscopy (EDX). It was found that precipitates ε-Fe2C within laths during quenching via auto-tempering. During reheating to tempering temperature ε-Fe2C was dissolved and replaced by cementite, θ-M3C, which predominately form on martensitic lath boundaries. Vanadium and molybdenum are known from literature to form cubic MC or hexagonal M2C carbides, respectively. In this work it was found that the small carbides in the early stage of tempering have predominantly a cubic MC structure, even if the V/Mo-ratio the studied steel was only 0.12. Later during tempering more stable carbides, such as M7C3 and M23C6, also form, and it was concluded that the M7C3 form both by separate nucleation and in-situ transformation on cementite. The latter phenomenon was seen as particles with a core of cementite and shell of M7C3 after 24 h at 600 °C of tempering.
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| 21. |
- Claesson, Erik, et al.
(author)
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Scanning precession electron diffraction study of carbide precipitation sequence in low alloy martensitic Cr-Mo-V tool steel
- 2023
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In: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 202
-
Journal article (peer-reviewed)abstract
- Precipitation of carbides after tempering of a medium carbon low alloyed Cr-Mo-V tool steel at 600 degrees C was studied with scanning precession electron diffraction (SPED) in a transmission electron microscope (TEM). The precipitation sequence was evaluated by mapping the carbide distribution on carbon extraction replicas prepared from samples tempered for different durations of up to 24 h. The SPED results were supplemented by equilibrium calculations and energy dispersive x-ray spectroscopy (EDX) measurements in a TEM. It was found that e-Fe2C precipitates within martensite laths during quenching via auto-tempering. During reheating to tempering temperature e-Fe2C was dissolved and replaced by cementite, 0-M3C, which predominately form on martensite boundaries. It was further found that the small carbides in the early stage of tempering have predominantly a cubic MC structure, even if the V/Mo-ratio of the studied steel was only 0.12, and it is known from literature that V and Mo form cubic MC or hexagonal M2C carbides, respectively. Later during tempering more stable carbides, such as M7C3 and M23C6, also form, and it was concluded that the M7C3 form both by separate nucleation and precipitation on the cementite/matrix interface. The latter phenomenon was seen as particles with a core of cementite and a shell of M7C3 after 24 h of tempering.
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| 22. |
- Claesson, Erik, et al.
(author)
-
Selective characterization of Mo-rich secondary carbides in medium carbon low alloyed tool steel by anomalous small angle x-ray scattering
-
Journal article (peer-reviewed)abstract
- Anomalous small angle X-ray scattering was used to study Mo (Mo) rich secondary carbides during tempering of medium carbon low alloyed tool steel. The scattering contrast of Mo-rich carbides varies systematically close to the absorption edge of Mo. No anomalous effect could be seen for the as-quenched sample. However, a clear effect could be seen for all tempered conditions. By studying the energy dependency of scattering invariant, Mo-rich carbides are believed to have a MC structure in the early stages of tempering. The -ratio is decreasing with time which is believed to be related to the formation M2C carbides. This is more pronounced for samples tempered at 600 °C as compared to 550 °C. The volume fraction was calculated using the ASAXS gradient method. At 550 °C the volume fraction of (Mo,V)C was increasing up to 24 h of tempering to 1.7·10-3. At 600 °C tempering a maximum in volume fraction was reached already after 1 h with 1.6·10-3 fraction. The size and number density of carbides are more stable at 550 °C compared to 600 °C.
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| 23. |
- Claesson, Hans, et al.
(author)
-
Rheological behaviour during UV-curing of a star-branched polyester
- 2002
-
In: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 44:1, s. 63-67
-
Journal article (peer-reviewed)abstract
- Using a rheometer coupled with an UV-light generator, the viscoelastic behaviour during the fast cure of star-branched polyester is investigated. The 32 arm star polymers consist of a hyperbranched polyester core, Boltorn(TM) and linear grafts of poly(E-caprolactone) (degree of polymerisation: 20-52) with methacrylate end groups. The resins are crystalline and the melting points range from 34 to 50degreesC; films can be formed and cured below 80degreesC. The crossover of G' and G was used as the gel point. The time to reach the gel point, a few seconds, increases linearly with molecular weight.
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| 24. |
- Claesson, Hans
(author)
-
Rheology and UV-curing of a star-branched polyester
- 2001
-
Licentiate thesis (other academic/artistic)abstract
- The use of powder coatings has increased steadily over thelast few decades. Their popularity is due to a number of majoradvantages they offer when compared to solvent-borne systems.Near zero VOC-content, reduced energy consumption and near 100%utilisation of the material are some of the advantages. Themain components in most thermoset powder coatings are a primaryresin and a binder. The coating is applied in powder form, thenbaked and cured i.e. cross-linked. Traditionally, thecross-link reaction has been controlled by temperature. Normalcuring temperatures range between 160 and 200 °C, and thusare not suitable for applications involving heat sensitivesubstrates such as wood and plastic. One way to lower thecuring temperature is by the introduction of semi-crystallinematerial with a suitable melting temperature. The advantage ofusing a crystalline resin is its rapid melting, a first ordertransition, versus the slow softening of an amorphous resin.Low curing temperature also requires an initiating system thatis activated at low temperatures while stable at roomtemperature. This is difficult to achieve with conventionalthermal initiators. In recent yearsUV-curing of powdercoatings has obtained increased attention in industrialresearch. This technique allows fast curing at lowertemperatures than conventional powder coatings. The researchinto UV-curing was triggered by the interest in using heatsensitive substrates. Other advantages are improved storagestability, elimination of premature reaction duringmanufacturing and better levelling since viscosity does notincrease until UV-irradiated. This thesis describes thesynthesis and characterisation of a series of branchedpolyesters and investigates their possible use as powdercoatings resins. The polyesters consist of poly(e-caprolactone)(PCL) (degree of polymerisation: 5-200) initiated fromhydroxyfunctional cores with methylmethacrylate end-capping .The cores utilised are: (1) 3rd-generation Boltorn, acommercially available hyperbranched polyester withapproximately 32 hydroxyl groups, (2) a 3rd-generationdendrimer with 24 hydroxyl groups, (3) a 3rd-generation dendronwith 8 hydroxyl groups, and (4) a linear PCL for comparison.All initiators are based on 2,2-bis(methylol) propionic acid(bis-MPA). The polymers and films were characterised using1H-NMR, 13C-NMR, SEC, rheometry, DMTA, DSC and a rheometercoupled with an UV-lamp. Measurements of zero shear rateviscosity showed that h0 increased exponentially with Mw, justas expected for star-branched polymers. For Boltorn-PCL anddendrimer-PCL, h0 is independent of Mw but dependant of the armMw (Ma). However, the dendron-PCL deviated from this behaviour.The dendron-PCL Ma was higher than that of Boltorn-PCL ordendrimer-PCL at the same h0. The resins are crystalline andthe melting points range from 34-50 °C; films can beformed and cured below 80 °C. Measurement of mechanicalproperties of cured films showed that the films from the low Mwpolymer were amorphous while those with high Mw werecrystalline. The viscoelastic behaviour during the fast cureshowed that the time to reach the gel point, a few seconds,increased linearly with molecular weight. The crossover ofG’and G’’was used as the gel point.
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| 25. |
- Claesson, Hans, et al.
(author)
-
Semi-crystalline thermoset resins : tailoring rheological properties in melt using comb structures with crystalline grafts
- 2004
-
In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 49:1, s. 13-22
-
Journal article (peer-reviewed)abstract
- Thermosetting resins with semi-crystalline grafts have been synthesized. An amorphous resin with epoxide groups was first functionalized with hydroxyl groups using 2,2-bis(methylol) propionic acid, bis-MPA in bulk at 155 degreesC. Functionalization with bis-MPA was monitored using FT-IR, FT-Raman and SEC. The reaction was complete in 30 min. Grafts of poly(epsilon-caprolactone) were then grown from the hydroxyl functional resin and end capped with methacrylate groups. The polymerization Of epsilon-caprolactone, performed in bulk at 110 degreesC using Sn(Oct)(2), was characterized using H-1 NMR and SEC. The obtained molecular weights agreed well with theoretical values. The final end capping was performed using methacrylic anhydride, and monitored with SEC and H-1 NMR, which indicated full substitution. Two combs were synthesized with different arm lengths, DP 10 and 20, and the obtained M-W were close to calculated values. The complex viscosity was measured from low to high temperature for the crystalline resins, the amorphous resin and blends thereof. Rheological data show a rapid decrease in viscosity within a temperature change of 10-15 degreesC for the crystalline resins while the amorphous resin exhibited a slow softening. The blends exhibited a behavior in-between that of the crystalline and the amorphous resin. Films were prepared from the pure resins and the blends. The films were cured using UV irradiation. The comb architecture of these resins has advantages such as crystallinity, high molecular weight and low viscosity, facilitating leveling and resulting in smooth films. The final film properties varied with the ratio of crystalline to amorphous resin, where increase in the amount of crystalline resin correlated with increased the flexibility.
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| 26. |
- Claesson, Hans, et al.
(author)
-
Synthesis and characterisation of star branched polyesters with dendritic cores and the effect of structural variations on zero shear rate viscosity
- 2002
-
In: Polymer. - 0032-3861 .- 1873-2291. ; 43:12, s. 3511-3518
-
Journal article (peer-reviewed)abstract
- A series of branched polyesters consisting of poly(epsilon-caprolactone) (PCL) (degree of polymerisation: 5-200) initiated from hydroxy-functional cores and end-capped with methylmethacrylate have been prepared. The cores were third-generation hyperbranched polyester, Boltorn, with approximately 32 hydroxyl groups, a third-generation dendrimer with 24 hydroxyl groups and a third-generation dendron with eight hydroxyl groups. Finally, a linear PCL was synthesised as a reference material. All initiators were based on 2,2-bis(methylol) propionic acid (bis-MPA). C-13 NMR spectra of the polymers showed that those with shorter arms contained unreacted hydroxyl groups on the core. Rheological measurements of zero shear rate viscosity, eta(0), showed that the branched polyesters had a considerably lower eta(0) than linear polyester with similar molecular weight. The low melt viscosity and the crystallity produced a theological behaviour suitable for the film formation process for powder coatings. Measurements of mechanical properties of cured films showed that those with low arm molecular weight, M-a, were amorphous while those of high M-a were crystalline.
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| 27. |
- Claesson, Hans, 1970-
(author)
-
Synthesis and Properties of Branched Semi-Crystalline Thermoset Resins
- 2003
-
Doctoral thesis (other academic/artistic)abstract
- This thesis describes the synthesis and characterization ofbranched semi-crystalline polymers. Included in this work isthe SEC characterization of a series of dendrimers. Thebranched semi-crystalline polymers were synthesized in order toinvestigate the concept of their use as powder coatings resins.This concept being that the use of branched semi-crystallinepolymers in a UV-cured powder coating system may offer a lowertemperature alternative thus allowing the use of heat sensitivesubstrates and the added benefit of a reduced viscositycompared to linear polymers.A series of branched poly(ε-caprolactone)’s (PCL)(degree of polymerization: 5-200) initiated from hydroxylfunctional initiators were synthesized. The final architectureswere controlled by the choice of initiator structure;specifically the dendritic initiators yielded starbranchedPCL’s while the linear initiator yielded comb-branchedPCL’s. The dendritic initiators utilized were: (1) a3rd-generation Boltorn H-30, commercially availablehyperbranched polyester with approximately 32 hydroxyl groups,(2) a 3rd-generation dendrimer with 24 hydroxyl groups, and (3)a 3rd-generation dendron with 8 hydroxyl groups. Linear PCL wassynthesized for comparison. All dendritic initiators are basedon 2,2- bis(methylol) propionic acid. The comb-branchedpolymers were initiated from a modified peroxide functionalpolyacrylate. The resins were end-capped withmethylmethacrylate in order to produce a cross-linkable system.The polymers and films were characterized using 1H NMR, 13CNMR, SEC, DMTA, DSC, FT-IR, FT-Raman, rheometry and a rheometercoupled to a UV-lamp to measure cure behavior.The star-branched PCL’s exhibited considerably lowerviscosities than their linear counterparts with the samemolecular weight for the molecular region investigated (2-550kg mol-1). It was also found that the zero shear viscosityincreased roughly exponentially with M.The PCL star-branched resins are semi-crystalline and theirmelting points (Tm) range from 34-50°C; films can beformed and cured below 80°C. The viscoelastic behaviourduring the cure showed that the time to reach the gel point, afew seconds, increased linearly with molecular weight. Thecrossover of G’and G’’was used as the gelpoint. Measurement of mechanical properties of films showedthat the low molecular weight polymers were amorphous whilethose with high molecular weight were crystalline after cure.The polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) fromoligo- and multifunctional initiators was evaluated utilizingcoordination and cationic polymerization. Two tin basedcatalysts, stannous(II) 2-ethylhexanoate and stannous(II)trifluoromethane sulfonate, were compared with fumaric acid.Fumaric acid under bulk conditions resulted in lowerpolydispersity and less chance of gelling. The synthesis ofstar-branched polymers was confirmed by SEC data. The starpolymers exhibited a Tg at 20-30°C and a Tm at about100°C.All semi-crystalline resins exhibited a fast decrease inviscosity at Tm. Blends of combbranched semi-crystalline resinsand amorphous resins exhibited a transition behavior inbetweenthat of pure semi-crystalline resins and that of amorphousresins.The SEC characterization of a series of dendrimers withdifferent cores and terminal groups showed that the core had animpact on the viscosimetric radius of the core while theterminal groups appeared to have no effect.Keywords:star-branched, semi-crystalline,comb-branched, ring-opening polymerization,poly(ε-caprolactone), dendritic, thermoset, lowtemperature curing, powder coating, UVcuring,poly(5,5-dimethyl-1,3-dioxane-2-one), size exclusionchromatography, rheology, dendritic aliphatic polyester
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| 28. |
- Eriksson, Mimmi, et al.
(author)
-
Direct Observation of Gas Meniscus Formation on a Superhydrophobic Surface
- 2019
-
In: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 13:2, s. 2246-2252
-
Journal article (peer-reviewed)abstract
- The formation of a bridging gas meniscus via cavitation or nanobubbles is considered the most likely origin of the submicrometer long-range attractive forces measured between hydrophobic surfaces in aqueous solution. However, the dynamics of the formation and evolution of the gas meniscus is still under debate, in particular, in the presence of a thin air layer on a superhydrophobic surface. On superhydrophobic surfaces the range can even exceed 10 μm. Here, we report microscopic images of the formation and growth of a gas meniscus during force measurements between a superhydrophobic surface and a hydrophobic microsphere immersed in water. This is achieved by combining laser scanning confocal microscopy and colloidal probe atomic force microscopy. The configuration allows determination of the volume and shape of the meniscus, together with direct calculation of the Young-Laplace capillary pressure. The long-range attractive interactions acting on separation are due to meniscus formation and volume growth as air is transported from the surface layer.
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| 29. |
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| 30. |
- Gedell, Stellan, 1959, et al.
(author)
-
Integrated Product and Production Model – Issues on Completeness, Consistency and Compatibility
- 2011
-
In: International Conference on Engineering Design, ICED'11, 15 - 18 August 2011, Technical University of Denmark.
-
Conference paper (peer-reviewed)abstract
- Product development of complex products and their corresponding production systems continue to provide challenges in industry as well as interesting and challenging research questions. Recent research in the area has aimed at increased understanding and development of an integrated product and production system-modeling framework supporting cross-functional collaboration and concurrency. In this context, a well-known challenge in industry is the problem of how to ensure correct and complete sets of parts for manufacturing of different product variants. In striving towards integrated modeling capabilities this is one of several fundamental problems to be addressed. Thus, this problem has been in focus for the research work reported on in this paper. The work includes a framing of the concepts of completeness, consistency, and compatibility. Based on this framing a case study is conducted exploring the possibilities and implications involved in using the modeling framework to include supporting functionality. The case study is ongoing and preliminary findings are included in this paper.
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| 31. |
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| 32. |
- Gerafi, Joel, et al.
(author)
-
Neglect and aphasia in the acute phase as predictors of functional outcome 7 years after ischemic stroke
- 2017
-
In: European Journal of Neurology. - : Wiley. - 1351-5101 .- 1468-1331. ; 24:11, s. 1407-1415
-
Journal article (peer-reviewed)abstract
- © 2017 EAN Background and purpose: Visuospatial inattention (VSI) and language impairment (LI) are often present early after stroke and associations with an unfavorable short-term functional outcome have been reported. The purpose of this study was to investigate whether a screening of VSI and LI as indicators of cortical symptoms early after stroke could predict long-term functional outcomes. Methods: A consecutive cohort of 375 patients with ischemic stroke was assessed for the occurrence of VSI at a median of 7 days after admission (interquartile range, 1–5 days) using the Star Cancellation Test and for LI (within the first 7 days) with the language item in the Scandinavian Stroke Scale. Seven years later, functional outcomes were assessed by the modified Rankin scale and Frenchay Activities Index in 235 survivors without recurrent stroke. Relationships between baseline predictors and functional outcome at 7 years were analyzed with bivariate correlations and multiple categorical regressions with optimal scaling. Results: The regression model significantly explained variance in the modified Rankin scale (R 2 = 0.435, P < 0.001) and identified VSI (P = 0.001) and neurological deficits (P < 0.001; Scandinavian Stroke Scale score without the language item) as the significant independent predictors. The model for Frenchay Activities Index was also significant (R 2 = 0.269, P < 0.001) with VSI (P = 0.035) and neurological deficits (P < 0.001) as significant independent predictors. Conclusions: Visuospatial inattention at acute stroke has an independent impact on long-term functional outcomes. Early recognition may enable targeted rehabilitative interventions.
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| 33. |
- Gulliksson, Magdalena, et al.
(author)
-
Expression of 15-lipoxygenase type-1 in human mast cells
- 2007
-
In: Biochimica et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 1878-2434. ; 1771:9, s. 1156-65
-
Journal article (peer-reviewed)abstract
- Mast cells play a key role in the pathophysiology of asthma. These cells exert their effector functions by releasing a variety of proinflammatory and immunoregulatory compounds. Mast cells infiltrate the bronchial epithelium and smooth muscle to a higher degree in patients with asthma compared to control subjects. 15-Lipoxygenase type-1 (15-LO-1) is a prooxidant enzyme which is expressed in asthmatic lungs leading to formation of pro- and anti-inflammatory mediators. Here we report that interleukin-4 (IL-4) induced the expression of 15-LO-1 in human cord blood derived mast cells (CBMC) as demonstrated by RT-PCR, western blot and immunocytochemistry. The major metabolite of arachidonic acid formed via the 15-LO pathway in IL-4 treated CBMC was identified as 15-ketoeicosatetraenoic acid (15-KETE, also named 15-oxo-ETE) with smaller amounts of 15-hydroxyeicosatetraenoic acid (15-HETE) as identified by HPLC and mass spectrometry (MS/MS). Furthermore, immunohistochemical stainings demonstrated the expression of 15-LO-1 in mast cells in lung and skin in vivo. Osmotic activation of CBMC with mannitol resulted in activation of the 15-LO-1 pathway. In conclusion, the expression of 15-LO-1 and release of 15-LO-1 derived products by mast cells may contribute to the role of these cells in asthma and other inflammatory diseases.
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| 34. |
- Han, Hongya, et al.
(author)
-
Human 15-lipoxygenase-1 is a regulator of dendritic-cell spreading and podosome formation
- 2017
-
In: The FASEB Journal. - : FEDERATION AMER SOC EXP BIOL. - 0892-6638 .- 1530-6860. ; 31:2, s. 491-504
-
Journal article (peer-reviewed)abstract
- Dendritic cells (DCs) involved in proinflammatory immune responses derive mainly from peripheral monocytes, and the cells subsequently mature and migrate into the inflammatory micromilieu. Here we report that suppressing of 15-lipoxygenase-1 led to a substantial reduction in DC spreading and podosome formation in vitro. The surface expression of CD83 was significantly lower in both sh-15-lipoxygenase-1 (15-LOX-1)-transduced cells and DCs cultivated in the presence of a novel specific 15-LOX-1 inhibitor. The T-cell response against tetanus-pulsed DCs was only affected to a minor extent on inhibition of 15-LOX-1. In contrast, endocytosis and migration ability of DCs were significantly suppressed on 15-LOX-1 inhibition. The expression of 15-LOX-1 in DCs was also demonstrated in affected human skin in atopic and contact dermatitis, showing that the enzyme is indeed expressed in inflammatory diseases in vivo. This study demonstrated that inhibiting 15-LOX-1 led to an impaired podosome formation in DCs, and consequently suppressed antigen uptake and migration capacity. These results indicated that 15-LOX-1 is a potential target for inhibiting the trafficking of DCs to lymphoid organs and inflamed tissues and decreasing the inflammatory response attenuating symptoms of certain immunologic and inflammatory disorders such as dermatitis.-Han, H., Liang, X., Ekberg, M., Kritikou, J. S., Brunnstro " m, angstrom., Pelcman, B., Matl, M., Miao, X., Andersson, M., Yuan, X., Schain, F., Parvin, S., Melin, E., Sjoberg, J., Xu, D., Westerberg, L. S., Bjorkholm, M., Claesson, H.- E. Human 15-lipoxygenase- 1 is a regulator of dendritic-cell spreading and podosome formation.
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| 35. |
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| 36. |
- Hedelin, Hans, et al.
(author)
-
Febrile reactions after transrectal ultrasound-guided prostatic biopsy: a retrospective study.
- 2011
-
In: Scandinavian journal of urology and nephrology. - : Informa UK Limited. - 1651-2065 .- 0036-5599.
-
Journal article (peer-reviewed)abstract
- Abstract Objective. The aim of this study was to evaluate the incidence and clinical presentation in patients with hospital admission owing to febrile infections after transrectal ultrasound-guided prostate biopsies. Material and methods. The case histories of the 57 patients (3.5%) who, between January 2006 and December 2009, were admitted owing to a febrile infection secondary to the 1633 transrectal prostate biopsies performed during the period were retrospectively analysed. Norfloxacin 400 mg × 2 was given for 3 days as prophylaxis starting just before or within 10 min of biopsy. Results. Quinolone-resistant Escherichia coli was isolated from blood cultures in 43% of the patients (n = 15) presenting with fever between 24 and 48 h postbiopsy. The urine culture was positive in 13% and no patient had symptoms suggestive of a urinary tract infection (UTI). In patients presenting after 48 h (n = 42), quinolone-resistant E. coli was never isolated from blood; E. coli was cultured from urine in 45% of the patients and in 48% it was associated with UTI symptoms. Conclusions. The finding that early postbiopsy fever was often associated with a quinolone-resistant E. coli bacteraemia and never with UTI symptoms, as opposed to late-onset fever, where such symptoms were common and quinolone-resistant E. coli was rarely detected, suggests divergent pathogenic mechanisms underpinning early- and late-onset febrile reactions. These findings have implications for how antibiotic prophylaxis should be given.
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| 37. |
- Hällgren, Anita, et al.
(author)
-
Frequency of aggregation substance, cytolysin and enterococcal surface protein in vitro adhesion to urinary catheters of E. faecalis and E. faecium of clinical origin
-
Other publication (other academic/artistic)abstract
- Enterococcal isolates, 21 E. faecium and 94 E. faecalis, isolated from blood cultures, rectal specimens and various other clinical samples were examined for the presence of the virulence factors hemolysin/cytolysin, aggregation substance (asa1) and enterococcal surface protein (esp). The isolates were previously characterized by pulsed-field gel electrophoresis (PFGE). Adhesion to siliconized latex urinary catheters was analysed in 14 clinical isolates and 3 control strains. Densities of adhering bacteria were determined by a bioluminescence assay of bacterial ATP. The only virulence factor found in E. faecium, esp, was found in 71% of the 21 E. faceium isolates. Cytolysin production, asa1 and esp were found in 13%, 79% and 73%, respectively, of the 94 E. faecalis isolates. Isolates belonging to a cluster of genetically related isolates differed significantly with respect to carriage of esp and asa1 compared to unique isolates, with the virulence factors more commonly found among clustered isolates (p<0.01). No difference was found with respect to cytolysio production (p = 0.76). E. faecalis isolates adhered with higher bacterial densities than E. faecium. E. faecalis isolates within the same PFGE cluster adhered with similar bacterial densities, but there was no association between adhesion and the presence of esp when isolates within the same cluster were compared (p = 0.38 and 0.64).
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| 38. |
- Hällgren, Anita, et al.
(author)
-
Molecular detection of aggregation substance, enterococcal surface protein, and cytolysin genes and in vitro adhesion to urinary catheters of Enterococcus faecalis and E. faecium of clinical origin
- 2009
-
In: International Journal of Medical Microbiology. - : Elsevier BV. - 1438-4221 .- 1618-0607. ; 299:5, s. 323-332
-
Journal article (peer-reviewed)abstract
- It has been hypothesized that nosocomial enterococci might have virulence factors that enhance their ability to colonise hospitalised patients. The objectives of this study were to investigate the prevalence of genes encoding 3 virulence factors: aggregation substance (asa1), enterococcal surface protein (esp), and 5 genes within the cytolysin operon (cylA, cylB, cylM, cylL(L), cylL(S)) and cytolysin production in 115 enterococcal clinical isolates (21 Enterococcus faecium and 94 E. faecalis). Adhesion to siliconized latex urinary catheters in relation to presence of esp was analysed in a subset of isolates. The isolates were previously characterised by pulsed-field gel electrophoresis (PFGE). esp was the only virulence gene found in E. faecium. It was found in 71% of the 21 E. faecium isolates. asa1, esp, and the cyl operon were found in 79%, 73% and 13% respectively, of the 94 E. faecalis isolates. There was a complete agreement between presence of the cyl operon and phenotypic cytolysin production. Isolates belonging to a cluster of genetically related isolates carried esp and asa1 more often when compared to unique isolates. No difference was found with respect to cyl genes. E. faecalis isolates adhered with higher bacterial densities than E. faecium. E. faecalis isolates within the same PFGE cluster adhered with similar bacterial densities, but there was no association between adhesion and the presence of esp when isolates within the same cluster were compared. In conclusion, E. faecalis isolates with high-level gentamicin resistance (HLGR) belonging to clusters of genetically related isolates widely distributed in Swedish hospitals, were likely to carry both esp and asa1. Adhesion was not affected by esp.
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| 39. |
- Ingason, Haukur, et al.
(author)
-
The Metro Project : Final report
- 2012
-
Reports (other academic/artistic)abstract
- This report compiles the results from the METRO project. The different parts of theproject – design fires, evacuation, integrated fire control, smoke control, extraordinarystrain onconstructions and fire- and rescue operations – are presented separately.The most complicated and expensive part of the project was the performance of thelarge scale fire and explosion tests in the Brunsberg tunnel, where the maximum heatrelease rates measured from the metro wagon was 77 MW.The main results from the project are new recommendations regarding design firesin mass transport systems, identification of key factors for fire and smoke spread in tunnelsand at stations as well as regarding the difficulties for disabled persons to evacuatefrom trains in tunnels, new recommended types of way guiding systems, safer design incase of explosions in trains and evaluation of the fire and rescue services’ possibilitiesand limitations in underground mass transport systems.
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| 40. |
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| 41. |
- Ingason, Haukur, et al.
(author)
-
The Metro Project: Final Report
- 2012
-
Reports (other academic/artistic)abstract
- The report compiles the results from the METRO-project. The different parts of the project; design fires, evacuation, integrated fire control, smoke control, extraordinary strain on constructions and fire- and rescue operations are presented separately. The most complicated and expensive part of the project was the performance of the large scale fire and explosion tests in the Brunsberg tunnel. The maximum heat release rates measured from the metro carriage was 77 MW. The maximum ceiling gas temperatures was 1118 °C. These values are high, and should be put into a perspective of the situation and the type of carriages used. The project is not recommending the highest values as the design fire, but values reflected in conditions. The egress study confirm that one of the major issues related to fire evacuation in underground transportation systems is that people often are reluctant to initiate an evacuation. New data show that participants moved with an average of 0.9 meters per second in the smoke filled environment (average visibility of 1.5–3.5 meters). A way-finding installation at the emergency exit, which consisted of a loudspeaker, was found to perform particularly well in terms of attracting people to the door. Two smoke control systems were simulated for a single exit metro station. The systems consisted of a pressurizing supply air system and mechanical exhaust ventilation system with and without platform screen doors. The results show that both the pressurizing supply air system and the mechanical exhaust air system provide effective smoke control for one exit metro station. The significance of the platform screen doors was shown to be important in relation to smoke control. Experiments and simulations have provided increased confidence in ability to simulate explosion scenarios to determine the pressure inside and outside a carriage and to be able to study variations of conditions such as carriage geometry and window designs. The explosion test performed show that an explosion with a relatively minor charge can significantly change the conditions for both evacuees and the rescue service. The results show that the conditions for evacuation and rescue operations can change dramatically as a result of a relatively minor explosion. Evaluation of methods and fire and rescue tactics in metros is given. Mapping of IR imaging as a tactical resource at tunnel fires was presented.
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| 42. |
- James, Anna, et al.
(author)
-
The influence of aspirin on release of eoxin C4, leukotriene C4 and 15-HETE, in eosinophilic granulocytes isolated from patients with asthma
- 2013
-
In: International Archives of Allergy and Immunology. - : S. Karger AG. - 1018-2438 .- 1423-0097. ; 162:2, s. 135-42
-
Journal article (peer-reviewed)abstract
- Background: The effect of aspirin on the release of key arachidonic acid metabolites in activated eosinophils from subjects with aspirin-intolerant asthma (AIA) has not been investigated previously, despite the characteristic eosinophilia in AIA. Methods: Peripheral blood eosinophils were isolated from four groups of subjects: healthy volunteers (HV; n = 8), mild asthma (MA; n = 8), severe asthma (SA; n = 9) and AIA (n = 7). In the absence or presence of lysine-aspirin, eosinophils were stimulated with arachidonic acid or calcium ionophore to trigger the 15-lipoxygenase-1 (15-LO) and 5-lipoxygenase (5-LO) pathways, respectively. 15(S)-hydroxy-eicosatetraenoic acid (15-HETE) and eoxin C4 (EXC4) were measured as 15-LO products and leukotriene (LT)C4 as a product of the 5-LO pathway. Results: Activated eosinophils from patients with SA and AIA produced approximately five times more 15-HETE than eosinophils from HV or MA patients. In the presence of lysine-aspirin, eosinophils from AIA, MA and SA patients generated higher levels of 15-HETE than in the absence of lysine-aspirin. Furthermore, in the presence of lysine-aspirin, formation of EXC4 was also significantly increased in eosinophils from AIA patients, and LTC4 synthesis was increased both in AIA and SA patients. Conclusions: Taken together, this study shows an increased release of the recently discovered lipid mediator EXC4, as well as the main indicator of 15-LO activity, 15-HETE, in activated eosinophils from severe and aspirin-intolerant asthmatics, and also elevated EXC4 and LTC4 formation in eosinophils from AIA patients after cellular activation in the presence of lysine-aspirin. The findings support a pathophysiological role of the 15-LO pathway in SA and AIA.
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| 43. |
- Jerkeman, Matilda, et al.
(author)
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Trends in survival after cardiac arrest: a Swedish nationwide study over 30 years
- 2022
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In: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645.
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Journal article (peer-reviewed)abstract
- AimsTrends in characteristics, management, and survival in out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) were studied in the Swedish Cardiopulmonary Resuscitation Registry (SCRR). Methods and resultsThe SCRR was used to study 106 296 cases of OHCA (1990–2020) and 30 032 cases of IHCA (2004–20) in whom resuscitation was attempted. In OHCA, survival increased from 5.7% in 1990 to 10.1% in 2011 and remained unchanged thereafter. Odds ratios [ORs, 95% confidence interval (CI)] for survival in 2017–20 vs. 1990–93 were 2.17 (1.93–2.43) overall, 2.36 (2.07–2.71) for men, and 1.67 (1.34–2.10) for women. Survival increased for all aetiologies, except trauma, suffocation, and drowning. OR for cardiac aetiology in 2017–20 vs. 1990–93 was 0.45 (0.42–0.48). Bystander cardiopulmonary resuscitation increased from 30.9% to 82.2%. Shockable rhythm decreased from 39.5% in 1990 to 17.4% in 2020. Use of targeted temperature management decreased from 42.1% (2010) to 18.2% (2020). In IHCA, OR for survival in 2017–20 vs. 2004–07 was 1.18 (1.06–1.31), showing a non-linear trend with probability of survival increasing by 46.6% during 2011–20. Myocardial ischaemia or infarction as aetiology decreased during 2004–20 from 67.4% to 28.3% [OR 0.30 (0.27–0.34)]. Shockable rhythm decreased from 37.4% to 23.0% [OR 0.57 (0.51–0.64)]. Approximately 90% of survivors (IHCA and OHCA) had no or mild neurological sequelae. ConclusionSurvival increased 2.2-fold in OHCA during 1990–2020 but without any improvement in the final decade, and 1.2-fold in IHCA during 2004–20, with rapid improvement the last decade. Cardiac aetiology and shockable rhythms were halved. Neurological outcome has not improved.
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| 44. |
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| 45. |
- Johansson, Mats, et al.
(author)
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Design of coating resins by changing the macromolecular architecture : solid and liquid coating systems
- 2003
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In: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 48:2-4, s. 194-200
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Journal article (peer-reviewed)abstract
- An increased demand for new and improved coating systems, both due to environmental as well as performance reasons, have appeared during the last decades. Techniques such low temperature curing powder coatings, radiation curable systems, and high solids have gained an increased interest and obtained significant market shares. Although improved in many aspects, these systems still have limited use in certain applications due to technical reasons. One way to change the properties of thermoset resins that has obtained significant interest during the last decade is by changing the molecular architecture of the resin. An example of polymers which exhibit different properties compared to conventional linear structures are highly branched, dendritic, polymers [1-3]. These polymers, for example, exhibit a higher solubility and lower melt viscosity compared to their linear counterparts. They can also be tailored with respect to functionality and polarity to adjust the properties for certain applications. Coating resins based on hyperbranched polymers have been described both for liquid UV-curable systems as well as powder coatings [4-6]. This presentation will focus on how properties of resins based on dendritic polymers can be tailored and how this can applied to coating systems such as powder coatings, radiation curable resins and no-solvent liquid systems. The correlation between resin structure and its properties both before and after cure will be discussed.
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| 46. |
- Johnsson, Anna-Karin, et al.
(author)
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COX-1 dependent biosynthesis of 15-hydroxyeicosatetraenoic acid in human mast cells
- 2021
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In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier. - 1388-1981 .- 1879-2618. ; 1866:5
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Journal article (peer-reviewed)abstract
- 15-hydroxyeicosatetraenoic acid (15-HETE) is an arachidonic acid derived lipid mediator which can originate both from 15-lipoxygenase (15-LOX) activity and cyclooxygenase (COX) activity. The enzymatic source determines the enantiomeric profile of the 15-HETE formed. 15-HETE is the most abundant arachidonic acid metabolite in the human lung and has been suggested to influence the pathophysiology of asthma. Mast cells are central effectors in asthma, but there are contradictory reports on whether 15-HETE originates from 15-LOX or COX in human mast cells. This prompted the current study where the pathway of 15-HETE biosynthesis was examined in three human mast cell models; the cell line LAD2, cord blood derived mast cells (CBMC) and tissue isolated human lung mast cells (HLMC). Levels and enantiomeric profiles of 15-HETE and levels of the downstream metabolite 15-KETE, were analyzed by UPLC-MS/MS after stimulation with anti-IgE or calcium ionophore A23187 in the presence and absence of inhibitors of COX isoenzymes. We found that 15-HETE was produced by COX-1 in human mast cells under these experimental conditions. Unexpectedly, chiral analysis showed that the 15(R) isomer was predominant and gradually accumulated, whereas the 15(S) isomer was metabolized by the 15hydroxyprostaglandin dehydrogenase. We conclude that during physiological conditions, i.e., without addition of exogenous arachidonic acid, both enantiomers of 15-HETE are produced by COX-1 in human mast cells but that the 15(S) isomer is selectively depleted by undergoing further metabolism. The study highlights that 15-HETE cannot be used as an indicator of 15-LOX activity for cellular studies, unless chirality and sensitivity to pharmacologic inhibition is determined.
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| 47. |
- Jonsson, Karin, et al.
(author)
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Urine cultures from indwelling bladder catheters in nursing home patients: A point prevalence study in a Swedish county.
- 2011
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In: Scandinavian journal of urology and nephrology. - : Informa UK Limited. - 1651-2065 .- 0036-5599.
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Journal article (peer-reviewed)abstract
- Abstract Objectives. To survey the bacterial flora and antibiotic resistance in urinary strains from patients with indwelling bladder catheters residing in nursing homes within a geographically defined region. Material and methods. Urine was sampled for culture from 163 catheter patients (126 men and 37 women) during a 2 week period in March 2010. Susceptibility testing of the isolated bacteria was compared with all urinary strains (n = 9994) from hospitals and primary healthcare in the same geographical area cultured during the first 6 months of 2010 (control group). Results. Bacteriuria was found in 159 of 163 urine samples (98%). Enterococcus faecalis and Escherichia coli were the most common species, one or both being detected in 72% of the urine samples, while Proteus species were found in10% and a single isolate of Providentia species was seen.Strains in the study patients were more resistant to antibiotics than in the control group. Particularly large differences were noted for ciprofloxacinin in E. coli (16.9% vs 7.9%) and for trimethoprim-sulfamethoxazole in E. faecalis (39.1% vs 24.8%). One extended spectrum β-lactamase (ESBL)-producing E. coli was cultured (1.3%), compared with 1.6% in the control group. No vancomycin-resistant enterococci (VRE) or methicillin-resistant Staphylococcus aureus (MRSA) were detected. Conclusions. Proteus mirabilis and Providentia species were rarely isolated, in sharp contrast to previous studies from geriatric hospital wards where they have often been in the majority. The limited incidence of ESBL and the absence of VRE and MRSA is gratifying, but the high resistance to antibiotics needs to be assessed on a continuous basis.
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| 48. |
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| 49. |
- Lin, Yuanyuan, et al.
(author)
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Experimental studies of single-sided ventilation for semi-enclosed models with horizontal opening
- 2024
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In: Proceedings of the 17<sup>th</sup> ROOMVENT Conference.
-
Conference paper (peer-reviewed)abstract
- As a preliminary investigation of the wind-driven purging process for densely built environments through the canopy layer, the ventilation efficiency of standalone semi-enclosed models incorporating a horizontal opening in the roof façade was investigated in the wind tunnel. For comparison, two models with different geometries were constructed, and each model was tested individually. Both models were equipped with replaceable roof covers, enabling the adjustment to the opening size. The ventilation efficiency was evaluated by continuous releasing and sampling of the tracer gas, from which the normalized purging velocity (PFVn) was derived. Additionally, the flow condition over the opening was monitored using the Laser Doppler Anemometer. It was found that separation flows from the frontal edge(s) of the model could introduce secondary circulations across large openings, resulting in dramatic increases in PFVn. Both the rectangular prism model and cylinder model possessed higher PFVn compared to prior studies on single-sided ventilation, while close values were observed with cylinder model mounted under the wind tunnel floor. Besides, the vertical distribution of integral length scales of streamwise velocity indicated the stratification feature of separation flows under low-turbulent incoming flow conditions. Measurement results provide validation data for further simulation studies including more detailed structures.
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