| 1. |
- Andersson, Mike, et al.
(författare)
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On the applicability of MISiCFET gas sensors regarding ammonia slip monitoring in small-scale boilers running SNCR
- 2007
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Gas sensitive Metal Insulator Silicon Carbide Field Effect Transistor – MISiCFET – devices have shown good possibilities of realizing sensors for high temperature applications. One such application could be the monitoring of ammonia slip from boilers running SNCR – Selective Non-Catalytic Reduction of nitrogen oxides (NOx) with ammonia (NH3). In this study a number of MISiCFET gas sensors operated at different temperatures and with both platinum (Pt) and iridium (Ir) as the gate contact have been tested for their ability to detect and quantify ammonia slip in flue gases from a 5.6 MW wood fired boiler during a test of a new SNCR-system. The individual sensors have been evaluated and compared to each other for the sensitivity towards NH3 and possible cross-sensitivities to other flue gas species through the comparison of the sensor signals with the signals from analytical instruments like FTIR – Fourier Transform Infrared spectroscopy – for nitrogen oxides (NO + NO2), NH3, and carbon monoxide (CO) and an FID – Flame Ionization Detector – for the Total Hydrocarbon Concentration (THC). The ability of a combination of sensors to provide extra or more accurate information about the NH3 concentration was also evaluated through the construction and validation of a Partial Least Squares – PLS – regression model based on all the sensor signals. Under the assumption that the sensors’ responses follow a logarithmic dependence on NH3 concentration the results regarding ammonia slip quantification were promising both for a single Ir sensor and for the system based on all sensors. There is still a question mark for the long-term stability of the devices in real flue gases, however.
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| 2. |
- Hartford, Marianne, 1944, et al.
(författare)
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C-reactive protein, interleukin-6, secretory phospholipase A(2) group IIA and intercellular adhesion molecule-1 in the prediction of late outcome events after acute coronary syndromes
- 2007
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Ingår i: J Intern Med. - : Wiley. - 0954-6820 .- 1365-2796. ; 262:5, s. 526-536
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Tidskriftsartikel (refereegranskat)abstract
- Objective. We investigated whether levels of C-reactive protein (CRP), interleukin-6 (IL-6), secretory phospholipase A(2) group IIA (sPLA(2)-IIA) and intercellular adhesion molecule-1 (ICAM-I) predict late outcomes in patients with acute coronary syndromes (ACS). Design. Prospective longitudinal study. CRP (mg L(-1)), IL-6 (pg mL(-1)), sPLA(2)-IIA (ng mL(-1)) and ICAM-1 (ng mL(-1)) were measured at days 1 (n = 757) and 4 (n = 533) after hospital admission for ACS. Their relations to mortality and rehospitalization for myocardial infarction (MI) and congestive heart failure (CHF) were determined. Setting. Coronary Care Unit at Sahlgrenska University Hospital, Gothenburg, Sweden. Subjects. Patients with ACS alive at day 30; median follow-up 75 months. Results. Survival was related to day 1 levels of all markers. After adjustment for confounders, CRP, IL-6 and ICAM-1, but not sPLA(2)-IIA, independently predicted mortality and rehospitalization for CHF. For CRP, the hazard ratio (HR) was 1.3 for mortality (95% confidence interval (CI): 1.1-1.5, P = 0.003) and 1.4 for CHF (95% CI: 1.1-1.9, P = 0.006). For IL-6, HR was 1.3 for mortality (95% CI: 1.1-1.6, P < 0.001) and 1.4 for CHF (95% CI: 1.1-1.8, P = 0.02). For ICAM-1, HR was 1.2 for mortality (95% CI: 1.0-1.4, P = 0.04) and 1.3 for CHF (95% CI: 1.0-1.7, P = 0.03). No marker predicted MI. Marker levels on day 4 provided no additional predictive value. Conclusions. In patients with ACS, CRP, IL-6, sPLA(2)-IIA and ICAM-1 are associated with long-term mortality and CHF, but not reinfarction. CRP, IL-6 and ICAM-1 provide prognostic information beyond that obtained by clinical variables.
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| 3. |
- Leul, Melakeselam, et al.
(författare)
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Molecular characterization of uptake hydrogenase in Frankia
- 2005
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Ingår i: Biochemical Society Transactions. - London : Biochemical Society. - 0300-5127 .- 1470-8752. ; 33:1, s. 64-66
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Tidskriftsartikel (refereegranskat)abstract
- A molecular characterization of uptake hydrogenase in Fronkia was performed by using two-dimensional gel electrophoresis, matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry, PCR amplification and Southern blotting. A polypeptide of approx. 60 kDa was recognized in Frankia UGL011102, AVCI1 and KBS on the two-dimensional gel by blotting with Ralstonia eutropha (Hox G) antibody. Further analysis by MS resulted in a peptide 'fingerprint', which was similar to the membrane-bound hydrogenase 2 large subunit (HYD2) in Escherichia coli. in addition, a 127 bp PCR fragment could also be amplified from Frankia AVCI1, which gave a 76% similarity with the large subunit of hydrogenase in, e.g., Azotobacter chrococcum, Bradyrhizobium japonicum and Rhizobium leguminosorum. Although immunological similarity between the small subunit of Frankia hydrogenase and that of other organisms has not yet been found, a PCR product of 500 bp could be amplified from the local source of Fronkia, the analysis of which gave 69 and 67% identity with the small subunit of hydrogenases in B. japonicum and R. leguminosorum respectively. A Southern-blot analysis further indicated evidence for the presence of the small hydrogenase subunit in other Fronkia strains, i.e. KBS, Avcl1 and Ccl3.
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| 4. |
- Mattsson, Anita
(författare)
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Flexibel utbildning i praktiken : En fallstudie av pedagogiska processer i en distansutbildning med en öppen design för samarbetslärande
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study is to examine the pedagogical processes that evolve in an "open" design for online learning realized in relation to a specific setting. The study describes and analyzes pedagogical activities in a distance education course in higher education that uses an asynchronous conference system for communication and interaction. The study's theoretical framework is based on the CSCL field, and a socio-cultural perspective, where the aim of the research is to create artefacts and environments that support meaning making in practice. The study was conducted in an authentic environment and can be described as an ethnographic exploratory case study. The analysis focuses on how the practice is established and constituted over time. The unit of analysis is ongoing interaction between nine groups of students and their teacher. Some overall patterns has been analysed and three models of division of labour emerged in the study. The produced assignments mirror the negotiations the groups’ members have in understanding how and when they will be working with the assignments. The course had a weak educational framing and the participants were responsible for their own learning. The teacher's instructions were intentionally broad and vague, an open design, which allowed the students to use their creativity in the work. Even if the teacher was responsible for monitoring the students' discussions, she did not participate because she thought it was too difficult to understand when her active participation supported the students and when it did not. The relations between and within the structuring resources were used in learning communities and the students acted in relation to them. To understand how to divide and allocate tasks, and how to solve problems, is not only done in relationships and people's thinking, but also implicit in learning communities. This means that teachers have to design courses in new ways. The requirements for participation, interaction, and communication, must be determined. The way in which an assignment is formulated structured the students' way to solve the assignments.
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| 5. |
- Mattsson, Anita, et al.
(författare)
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Silence on the Net : Distance Education Design in a CSCL and Community of Practice Framework
- 2008
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Ingår i: Proceedings of SITE 2008. - Waynesville, NC USA : Association for the Advancement of Computing in Education. - 9781880094648 ; , s. 549-556
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Konferensbidrag (refereegranskat)abstract
- This paper is about distance education design in a CSCL framework, building on theories of communities of practice. One teacher and nine student groups in higher education have been followed during one course. An analysis is made on1098 posted contributions, and interviews made with all participants. The result shows that the teacher says she is embraced by socio cultural theories. However, in practice she carries through the course in a constructivist manner, leaving it up to the students to form their pedagogical practice to a great extent on their own. Structuring assignments, feedback, designing for the unexpected, teacher as a co-learner, are aspects highlighted in the analysis.
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| 6. |
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| 7. |
- Unéus, Lars, 1971-, et al.
(författare)
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Evaluation of on-line flue gas measurements by MISiCFET and metal-oxide sensors in boilers
- 2005
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 5:1, s. 75-81
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Tidskriftsartikel (refereegranskat)abstract
- Metal insulator silicon carbide field-effect transistor sensors, metal-oxide sensors, and a linear Lambda sensor in an electronic nose was used to measure on-line in hot flue gases from a boiler. Flue gas from a 100-MW pellets-fuelled boiler has been used to feed the experimental setup. Several reference instruments, which measure the flue gases in parallel to the sensor array, are connected to the electronic nose. Data was collected during six weeks and then evaluated. Using principal component analysis as the data evaluation method, different operating modes for the boiler have been identified in the data set. The different modes could be described in terms of high or low O 2 and CO concentration. Furthermore, we have shown that it seems possible to use a sensor array to determine the operating mode of the boiler and, by partial least-squares models, measure the CO concentration when the boiler operates in its optimum mode.
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