| 1. |
- Jensen Wolfhechel, Ola, 1965-, et al.
(author)
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Norrlands vattenanknutna kulturmiljöer – en förstudie : rapport från ett FoU-projekt
- 2022
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Reports (other academic/artistic)abstract
- Syftet med föreliggande förstudie har varit att ta fram ett underlag inför ett kommande tvärvetenskapligt forsknings- och digitaliseringsprojekt. Bakgrunden är att Riksantikvarieämbetet under 1940-1980-talen genomförde omfattande arkeologiska, men även naturvetenskapliga och etnologiska, undersökningar vid Norrlands älvar och sjöar som ett led i vattenkraftsutbyggnaden. Materialet kom under 1960-1980-talen att bearbetas tillsammans med Stockholms universitet inom ramen för det tvärvetenskapliga projektet Norrlands Tidiga Bebyggelse. Insatserna resulterade i ett rikt material som idag förvaras i Riksantikvarieämbetets arkiv. Då stora delar av Norrland alltjämt är antikvariskt eftersatta utgör det ett mycket viktigt källmaterial för både forskning och förvaltning av dess kulturmiljöer.Det långsiktiga målet med förstudien och det kommande projektet är att skapa ett kunskapsunderlag för forskning och redskap för landskapsanalyser som leder till ett hållbart bevarande och förvaltning av Norrlands vattenanknutna kulturmiljöer. Inom förstudien har en rad viktiga forsknings- och förvaltningsområden identifierats. För att ta fram ett adekvat underlag inför ansökan har den bland annat mynnat ut i olika förslag på strategier för det kommande projektets genomförande och finansiering, en fördjupning av frågor som rör förvaltning av vattenanknutna kulturmiljöer, utvecklat tvärvetenskapliga forskningsfrågor, tagit fram en digitaliseringsstrategi, formaliserat ett nätverk och en referensgrupp, genomfört en behovsanalys samt en inventering för att identifiera relevant arkivmaterial inom projektdeltagarnas respektive institutioner. Med förstudien har vi således lagt grunden till ett tvärvetenskapligt forsknings- och digitaliseringsprojekt som inkluderar kulturmiljöförvaltning, arkeologi, etnologi, sociologi och naturveten-skapliga ämnen, däribland miljö- och klimatforskning.
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| 2. |
- Andersson, Hans, et al.
(author)
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Complete regioselective addition of grignard reagents to pyrazine N-oxides, toward an efficient enantioselective synthesis of substituted piperazines.
- 2010
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In: Organic letters. - : American Chemical Society (ACS). - 1523-7052 .- 1523-7060. ; 12:2, s. 284-6
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Journal article (peer-reviewed)abstract
- A conceptually new one-pot strategy for the synthesis of protected substituted piperazines via the addition of Grignard reagents to pyrazine N-oxides is presented. This strategy is high yielding (33-91% over three steps), step-efficient, and fast. The synthesized N,N-diprotected piperazines are convenient to handle and allow for orthogonal deprotection at either nitrogen for selective transformations. In addition, this is a synthetic route to enantiomerically enriched piperazines by using a combination of phenyl magnesium chloride and (-)-sparteine, which resulted in enantiomeric excesses up to 83%.
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| 3. |
- Andersson, Hans, et al.
(author)
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Efficient, mild and completely regioselective synthesis of substituted pyridines
- 2010
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In: Chemical Communications. - : RSC Publishing. - 1359-7345 .- 1364-548X. ; 46:19, s. 3384-3386
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Journal article (peer-reviewed)abstract
- Addition of Grignard reagents to pyridine N-oxides in THF at low temperature (-78 to -20 °C) and treatment with TFAA provides an efficient general procedure for synthesis of substituted pyridines. The method is compatible with a range of functional groups such as esters, halogens and nitriles.
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| 4. |
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| 5. |
- Andersson, Roger, 1967-, et al.
(author)
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An asymmetric dialysis tube as an integrated part of a pressure-monitoring sensor
- 2001
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In: Technology and Health Care. - 0928-7329 .- 1878-7401. ; 9:5, s. 417-425
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Journal article (peer-reviewed)abstract
- A sensor has been designed consisting of a tube holder with a force transducer and a tube with a modified cross-section. The holder has a lid that encloses the tube. By having a stiff holder and a compliant tube, the idea is that the intraluminal pressure in the tube can be obtained from the measured force. The method is intended for non-invasive pressure measurements in blood or dialysate tubes.We have used a tube cross-sectional geometry where the outer surface is elliptic and the inner surface is circular with a relation of 2:1 between the thinnest and thickest tube sides. The pressure transducer system shows a linear relationship between the applied pressure and the sensor output (r = 0.999). Within the temperature range, 32°–36°C, which corresponds to the blood and dialysate temperatures, the sensor accuracy is within ±0.8 kPa (±6 mm Hg). This indicates that the sensor should be clinically useful during dialysis and similar applications.
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| 6. |
- Andersson, Roger, 1967-, et al.
(author)
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Cross-sectional changes in an asymmetric tube with bearing on non-invasive pressure measurements
- 2003
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In: Technology and Health Care. - 0928-7329 .- 1878-7401. ; 11:1, s. 11-20
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Journal article (peer-reviewed)abstract
- This study aims at investigating the radial dimensional changes, as a result of an applied intraluminal pressure for an elastic tube with non-uniform cross section. The study is related to a method for non-invasive pressure measurement using the extracorporeal tube as part of the sensor. The intended application is for monitoring of pressure in the blood and dialysate tubes during haemodialysis. The intention is to find a tube cross-section geometry that results in an expansion of the tube so that it is suitable to use as a component in a pressure sensor. The tube should have high radial compliance and expand in a well-defined manner to be able to transfer the intraluminal pressure to a transducer element sensing the radial force. Radial expansion was studied experimentally for tubes with different cross-section geometries. For small tube expansions the resolution in the experimental measurements was not sufficient to study the radial expansion. In this case, numerical simulation was performed. We conclude that a tube with essentially elliptic outer surface and circular inner surface, with a relation of 1:2 between the size of the thin and thick wall, results in a radial expansion upon application of pressure indicating that this tube is suitable for use as part of a sensor.
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| 7. |
- Andersson, Roger, 1967-, et al.
(author)
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Force to restore the shape of an asymmetric extracorporeal tube as the basis for non-invasive pressure measurements
- 2002
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In: International Journal of Artificial Organs. - 0391-3988 .- 1724-6040. ; 25:4, s. 281-289
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Journal article (peer-reviewed)abstract
- A zero-balance principle is described where intraluminal pressure is estimated from the counter force needed to restore the tube shape of an elastic extra corporeal tube. The aim was to optimise cross-sectional tube geometry for tube expansion due to pressure and to reduce the sensitivity to variation in mechanical tube characteristics using an experimental statistical and factorial design. The main application is pressure monitoring in blood and dialysate tubes during hemodialysis. Improving the monitoring of the dialysis process will reduce complications, such as sudden decreases in systemic blood pressure or occlusion at the artero-venous fistula. The factorial design indicated strong influence from the geometrical characteristics of the tube as well from the geometrical design parameters of the pressure transducer. We found a consistent relationship between the intraluminal pressure and the applied force needed to restore the tube shape. The modified cross-sectional tube geometry enhances measurement sensitivity and facilitates the desired behavior of tubes during pressure applications.
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| 8. |
- Andersson, Roger, 1967-
(author)
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Monitoring principles for haemodialysis
- 2002
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Doctoral thesis (other academic/artistic)abstract
- This thesis deals with non-invasive monitoring techniques for haemodialysis. Three applications in particular have been investigated: Blood pressure measurements in the extra corporal circuit, the relationship between UV measurements and dialysate urea concentration and photoplethysmography (PPG) in haemodialysis patients.A non-invasive pressure sensor as an integrated part of the extracorporeal tube circuit was developed using modified cross-section tube geometry. The expansions of the modified tubes with different cross-sectional geometries were studied upon application of pressure, both experimentally and numerically, using the finite element method. Factorial design was used to study the relationship between pressure in the tube and force needed to restore the expanding tube to its original dimension. This investigation was performed for different tube cross-sectional geometries. A pressure sensor was designed, based on the previously obtained findings. The evaluation of the pressure sensor showed that the output corresponded well to applied pressure (R2=0.99).An UV-method for studying waste products in the dialysate has recently been developed by our research group. In the present study, it was investigated how the relationship between UV-absorption and dialysate urea concentration was affected by the treatment settings, patient anamnesis and prescribed pharmaceuticals. A mathematical model was proposed which includes these effects. Multiregression analysis indicated the possibility of performing individual estimates of urea concentration from UV-absorption.During haemodialysis, the patient's cardiovascular system is affected when excess fluid is extracted, which may result in blood pressure fluctuations. In the present study, a novel PPG method for monitoring haemodynamic changes during dialysis was investigated. The performed study indicates that PPG measurements relate to haemodynamic changes and may thus be useful in the patient monitoring. However, the relationship is complex and needs further studies.
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