| 1. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 2. |
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| 3. |
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| 4. |
- Björkegren, Johan L M, et al.
(författare)
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Plasma cholesterol-induced lesion networks activated before regression of early, mature, and advanced atherosclerosis.
- 2014
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7404 .- 1553-7390. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- Plasma cholesterol lowering (PCL) slows and sometimes prevents progression of atherosclerosis and may even lead to regression. Little is known about how molecular processes in the atherosclerotic arterial wall respond to PCL and modify responses to atherosclerosis regression. We studied atherosclerosis regression and global gene expression responses to PCL (≥80%) and to atherosclerosis regression itself in early, mature, and advanced lesions. In atherosclerotic aortic wall from Ldlr(-/-)Apob (100/100) Mttp (flox/flox)Mx1-Cre mice, atherosclerosis regressed after PCL regardless of lesion stage. However, near-complete regression was observed only in mice with early lesions; mice with mature and advanced lesions were left with regression-resistant, relatively unstable plaque remnants. Atherosclerosis genes responding to PCL before regression, unlike those responding to the regression itself, were enriched in inherited risk for coronary artery disease and myocardial infarction, indicating causality. Inference of transcription factor (TF) regulatory networks of these PCL-responsive gene sets revealed largely different networks in early, mature, and advanced lesions. In early lesions, PPARG was identified as a specific master regulator of the PCL-responsive atherosclerosis TF-regulatory network, whereas in mature and advanced lesions, the specific master regulators were MLL5 and SRSF10/XRN2, respectively. In a THP-1 foam cell model of atherosclerosis regression, siRNA targeting of these master regulators activated the time-point-specific TF-regulatory networks and altered the accumulation of cholesterol esters. We conclude that PCL leads to complete atherosclerosis regression only in mice with early lesions. Identified master regulators and related PCL-responsive TF-regulatory networks will be interesting targets to enhance PCL-mediated regression of mature and advanced atherosclerotic lesions.
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| 5. |
- Cedergren, Anders, et al.
(författare)
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Determination of water in NIST reference material for mineral oils
- 2000
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Ingår i: Analytical Chemistry. - 0003-2700 .- 1520-6882. ; 72:14, s. 3392-3395
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Tidskriftsartikel (refereegranskat)abstract
- The accuracy of the reference concentrations of moisture in electrical insulating oil RM 8506 and lubricating oil RM 8507 (both of mineral type) and specified by the National institute of Standards and Technology (NIST) as containing 39.7 and 76.8 ppm (w/w) water, respectively, has recently been the subject of debate in this journal. To shed some further light on this controversy, we report in this correspondence results for these oils obtained by two additional methods, one based on specially designed reagents for diaphragm-free Karl Fischer (KF) coulometry and the other based on the concept of stripping at elevated temperature/continuous KF coulometry. A positive interference effect was shown to take place for RM 8506 when the direct coulometric method was used. If the results are corrected for this, the values including six different procedures varied in the range 13.5-15.6 ppm (w/w). For RM 8507, all values were between 42.5 and 47.2 ppm (w/w), which means that the values recommended by NIST for both reference oils using volumetric titration are about twice as high as those obtained with the other techniques. A possible explanation for this discrepancy is presented.
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| 6. |
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| 7. |
- Cedergren, Anders, et al.
(författare)
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Progress in Karl Fischer coulometry using diaphragm-free cells
- 2001
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Ingår i: ANALYTICAL CHEMISTRY. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 73:22, s. 5611-5
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Tidskriftsartikel (refereegranskat)abstract
- Different designs of a semiopen, drainable cathode compartment of a medium-sized coulometric Karl Fischer (KF) cell for the determination of water in the range 0.1-500 mug were evaluated. The main criterion for the design was to keep the resistance between the anolyte and catholyte low enough to permit the generation of currents larger than 20 mA (for an output voltage of 28 V). It was found that a good compromise between the size of this current and a minimal influence from diffusing/migrating oxidizable reduction products from the catholyte was achieved by means of an interface having a channel length and diameter of 8 and 2.1 mm, respectively (catholyte volume, similar to1 mL). To show the general applicability of the concept, the following different types of coulometric reagents suitable for nonpolar and polar samples, as well as for samples containing active carbonyl compounds, were investigated: Hydranal Coulomat A, AD, AX, AG-H (modified with chloroform, Merck), and two homemade methanolic reagents modified with 40% (v/v) chloroform and 50% (v/v) formamide, respectively. Except for Hydranal Coulomat A, the mean value of five consecutive titrations of 50 mug water did not deviate by more than 0.2% from the expected value for all reagents. Draining after every titration was sufficient to obtain accurate results, even for Coulomat A which, when used in the commercial diaphragm-free system of Metrohm, gave values which were about 10% too high. As compared to earlier reported results for diaphragm-free coulometry, the descibed modified cell represents a significant improvement, mainly because of the high accuracy achieved for all types of reagents.
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| 8. |
- Cedergren, Anders
(författare)
-
Stabstjänst
- 2018
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Ingår i: Militära arbetsmetoder. - Malmö : Universus Academic Press. - 9789187439476 ; , s. 235-253
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Bokkapitel (refereegranskat)
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| 9. |
- Cedergren, Alexander, et al.
(författare)
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Understanding practical challenges to risk and vulnerability assessments : the case of Swedish municipalities
- 2019
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Ingår i: Journal of Risk Research. - : Informa UK Limited. - 1366-9877 .- 1466-4461. ; 22:6, s. 782-795
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Tidskriftsartikel (refereegranskat)abstract
- Assessing risks and vulnerabilities in the multifaceted context of a municipality is challenging. There is a plethora of methods and tools to support this task. However, to achieve successful outcomes from Risk and Vulnerability Assessments (RVAs), merely applying theoretically and technically rigorous methods is far from enough; the question of how a method is implemented in a practical context is crucial for reaching intended outcomes. In this paper, we broaden the scope, from a strict consideration of technical and methodological matters, to a presentation of the more elusive challenges in accomplishing RVAs that are actually useful in a local context. We conduct and contrast two independent studies that were aimed at identifying general challenges in achieving a successful RVA process in Swedish municipalities. Based on the findings, we argue that there is a need for a considerably increased focus on municipal practices and on the implementation of methods in the practical context. Knowledge and understanding of such practical challenges are pivotal for efforts aimed at both developing methods for RVA and improving the entire RVA process.
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| 10. |
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| 11. |
- Cedergren, Marie, 1963-, et al.
(författare)
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Chlorination byproducts and nitrate in drinking water and risk for congenital cardiac defects
- 2002
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Ingår i: Environmental Research. - : Elsevier BV. - 1096-0953 .- 0013-9351. ; 89:2, s. 124-130
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Tidskriftsartikel (refereegranskat)abstract
- Drinking water disinfection byproducts have been associated with an increased risk for congenital defects including cardiac defects. Using Swedish health registers linked to information on municipal drinking water composition, individual data on drinking water characteristics were obtained for 58,669 women. Among the infants born, 753 had a cardiac defect. The risk for a cardiac defect was determined for ground water versus surface water, for different chlorination procedures, and for trihalomethane and nitrate concentrations. Ground water was associated with an increased risk for cardiac defect when crude rates were analyzed but after suitable adjustments this excess rate was found to be determined by chlorination procedures including chlorine dioxide. Chlorine dioxide appears itself as an independent risk factor for cardiac defects (adjusted odds ratio 1.61 (95% CI 1.00-2.59)). The risk for cardiac defects increased with increasing trihalomethane concentrations (P = 0.0005). There was an indicated but statistically nonsignificant excess risk associated with nitrate concentration. The individual risk for congenital cardiac defect caused by chlorine dioxide and trihalomethanes is small but as a large population is exposed to public drinking water, the attributable risk for cardiac defects may not be negligible. (C) 2002 Elsevier Science (USA).
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| 12. |
- Cedergren, Marie, 1963-, et al.
(författare)
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Detection of fetal structural abnormalities by an 11-14-week ultrasound dating scan in an unselected Swedish population
- 2006
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : Wiley. - 0001-6349 .- 1600-0412. ; 85:8, s. 912-915
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Tidskriftsartikel (refereegranskat)abstract
- Background. To determine the detection rate of fetal structural abnormalities by a routine 11-14-week ultrasound scan for dating in an unselected pregnant population. Methods. A prospective observational cohort study of 2,708 unselected pregnant women attending an abdominal ultrasound examination at 11-14 weeks gestation. The number of major fetal structural abnormalities diagnosed after birth was obtained from a computerized database at the same unit. Results. Out of 2,708 pregnant women, 89 (3.3%) were found to have a missed abortion at the time of the ultrasound scan and 33 (1.2%) were diagnosed as twins. Thirteen major structural abnormalities were detected, three cases of anencephaly (one case also had a spina bifida), one case with hydranencephaly, one fetus with Dandy-Walker syndrome, two cases with gastroschisis, one case with a bilateral hydronephrosis, one case with a generalized hydrops, one fetus with multiple malformations, and three cystic hygromas. An additional 19 major structural defects were detected at birth. Four cases of neural tube defects and nine fetuses with congenital heart defects were diagnosed. The antenatal ultrasound detection rate was 40.6% (13/32). Nine patients had a nuchal translucency greater than 3.0 mm (excluding cystic hygromas), two of them had chromosomal abnormalities (trisomy 21 and trisomy 18). Conclusions. Fetal structural abnormalities were detected in 41% (95%CI = 24-59) of the cases in an unselected pregnant population at a routine 11-14-week ultrasound scan for dating purpose. Two out of nine fetuses with a nuchal translucency greater than 3.0 mm had a chromosomal abnormality. © 2006 Taylor & Francis.
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| 13. |
- Cedergren, Marie, 1963-, et al.
(författare)
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Geographic variations in possible risk factors for severe cardiac malformations
- 2002
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Ingår i: Acta Pædiatrica. - : Wiley. - 1651-2227 .- 0803-5253. ; 91:2, s. 222-228
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate various putative risk factors in a county in Sweden, described as having a 28% increased prevalence of cardiovascular malformations, and to compare them with the risk factors in two reference counties. Women giving birth in the studied counties differed in age and parity distribution, smoking, and educational level but these differences could not explain the increased risk of cardiovascular malformations in the county, since after stratification for these variables, the risk, estimate did not change substantially. A number of potential risk factors were studied in a case/control design: spontaneous abortions, involuntary childlessness, maternal disease, body mass index, medical drug use, alcohol use, parental employment, paternal age, and urban/rural residency. No single factor could be attributed to the increased rate, with the exception of living in a rural district, Nearly all risk factors, however, were stronger in the county studied than those in the reference counties (0.02 > p > 0.01). Conclusion: The only single putative risk factor that could have contributed to the increased risk for cardiac defects described in the county Studied was maternal residency in a rural district. Notably, nearly all potential risk factors studied were stronger in the counts studied compared with those in the reference area. A conceivable explanation is that one or more unidentified factors related to rural residency could potentiate prevalent and weak teratogenic risk factors for cardiac defects.
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| 14. |
- Cedergren, Marie, 1963-, et al.
(författare)
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Risk factors for cardiovascular malformation - a study based on prospectively collected data
- 2002
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 28:1, s. 12-17
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Tidskriftsartikel (refereegranskat)abstract
- Objectives The aim of this study was to identify risk factors for cardiovascular malformation. Methods In a case-referent study prospectively collected data were obtained from original medical records. The study included 277 woman who had infants with a severe cardiac defect, and for each case two referents (medical records study) were included. Data on parental age, maternal reproductive history, disease in early pregnancy, reported maternal use of drugs and alcohol, smoking habits, parental occupation, and maternal body mass index (BMI) were extracted. When data were available from Swedish medical health registers, a comparison was made (register study) between all infants with cardiovascular defects (2208) and all infants born (175 768). Results Maternal diabetes mellitus was associated with an increased risk for cardiovascular malformation [odds ratio (OR) 2.38, 95% confidence interval (95% CI) 1.36-4.15], as was a high BMI (> 29) (OR 1.46, 95%CI 1.12-1.90). A tendency towards an increased risk was found for involuntary childlessness, spontaneous abortion, thyroid drugs, and nonsteroid anti-inflammatory drugs. Conclusions Some known risk factors for cardiac defects (eg, maternal diabetes mellitus and the use of antiepileptics) could be identified. Other postulated risk factors could not be verified, for example, paternal age and parental occupation. The use of medicinal drugs seems not to be a major factor in the etiology of cardiac defects. It is possible, however, that there is an association with the use of nonsteroid anti-inflammatory drugs or drugs for thyroid disease. The relationship between a high BMI and cardiovascular malformation observed in this study may be explained by impaired maternal glucose tolerance.
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| 15. |
- Cedergren, Stefan, et al.
(författare)
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A Performance Evaluation Framework for Innovation a chapter in Innovation in Business and Enterprise: Technologies and Frameworks
- 2010
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Ingår i: Innovation in Business and Enterprise. - : IGI Global. - 9781615206438 ; , s. 135-149
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter presents a framework for a conceptual evaluation of the performance of industrial product innovation activities. The framework promotes a holistic view of performance by considering three categories of activities: Planning, Implementation, and Sales and Delivery. Successful performance evaluation comes from acknowledging the fact that there are different objectives for each of the three activity categories. Moreover, performance may be expressed as a function of the performance of the Planning, the Implementation, and the Sales and Delivery activities. In this chapter the results of research involving seven large companies in Sweden, with the objective of improving the understanding of what is required to be successful when developing complex industrial products, are presented. Key factors for success as well as some general conclusions are discussed.
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| 16. |
- Cedergren, Stefan, et al.
(författare)
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Challenges with Evaluating Performance in Product Development
- 2010. - 8
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Ingår i: 17TH INTERNATIONAL PRODUCT DEVELOPMENT MANAGEMENT CONFERENCE. - Murcia, Spain.
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Konferensbidrag (refereegranskat)abstract
- The purpose of this paper is to from a managerial perspective investigate performance evaluation practices in a product development context. The focus is on exploring how managers perceive and evaluate performance in a software-intensive product development context. The research approach pursued in this research consist of a literature review combined with focused group interviews and exploratory multiple case studies. Moreover, a number of seminars have been held to discuss the findings both in academia and in practice. The result of this research indicates that product development managers are dissatisfied with their current way of evaluating performance. Performance measurements and the perception of performance are focused on cost, time and quality, i.e. what is easily measurable and not necessarily what is important. The dimensions of value creations and learning are missing. It is argued that manager perception of performance is affected by how it is measured, hence limiting the scope of the performance criteria. Thus, a change in the way managers perceive performance is necessary before there can be any change in the way performance is evaluated. Managers within product development that are dissatisfied with their performance measurement system should focus on how the organization perceive performance. By developing relevant performance criteria the first step in developing an effective performance evaluation system is made.
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| 17. |
- Cedergren, Stefan, et al.
(författare)
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Evaluation of performance in a product development context
- 2010. - 4
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Ingår i: Business Horizons. - : Elsevier. - 0007-6813 .- 1873-6068. ; 53:4, s. 359-369
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Tidskriftsartikel (refereegranskat)abstract
- In today's competitive environment, the need is greater than ever to deploy product development investments more effectively. To assist managers, we have developed two conceptual tools to support the evaluation of performance in product development. The Performance Measurement Evaluation Matrix (PMEX) helps managers evaluate performance measurement systems they currently use, in order to identify areas requiring improvement. Results from using the PMEX indicate that it is common to associate performance measurements with the efficiency aspects of time, cost, and quality, without monitoring the value created. Performance is largely perceived by managers in terms of time, cost, and quality of the activities in the later phases of the development process. We contend that an effective performance measurement system is based on performance criteria, and then derives measurements based on these. It is argued that there should be a change in the perception of performance, before performance evaluation systems can be improved. The Product Development Organizational Performance Model (PDOPM) assists in developing the perception of performance by relating uncertainty, efficiency, and effectiveness at three generic activity levels within the product development function. The use of our tools provides an improved perception of performance and its measurement, thus enabling improvements to the evaluation of performance.
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| 18. |
- Cedergren, Stefan, et al.
(författare)
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PMEX — A PERFORMANCE MEASUREMENT EVALUATION MATRIX FOR THE DEVELOPMENT OF INDUSTRIAL SOFTWARE-INTENSIVE PRODUCTS
- 2011. - 6
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Ingår i: International Journal of Innovation and Technology Management (IJITM). - : World Scientific Publishing. ; 8:1, s. 55-76
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Tidskriftsartikel (refereegranskat)abstract
- The ability to measure performance is both fundamental to and critical in successful product development. Previous research has focused on adding new measurements, not on evaluating those currently used. The performance measurement evaluation matrix (PMEX) is a tool to evaluate the performance-measurement system based on success factors in the development of software-intensive products. Three case studies have been conducted to test the PMEX and the results indicate that the PMEX enables managers to determine explicitly what is and what is not measured. Time, cost, and quality seem to be the focus of the performance measurements while technology and planning activities are absent.
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| 19. |
- Cedergren, Stefan, et al.
(författare)
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Towards Integrating Perceived Customer Value in the Evaluation of Performance in Product Development
- 2010. - 7
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Ingår i: PICMET 2010. - : IEEE. - 9781890843229
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Konferensbidrag (refereegranskat)abstract
- Product delivering companies invest resources in product development activities in order to create value. Still, when performance in product development is to be evaluated, time, cost, and quality are in focus, especially in the later stages of the development when it is expensive and difficult to make any changes. Time, cost, and quality are important dimensions of performance but they are not revealing the complete picture. Missing is the value perspective. This paper outlines a method for how perceived customer value can be used to evaluate performance in product development and describes how it is verified through a case study. By using the perceived customer value of requirements, the value propagation throughout the development is possible to monitor based on both market and scope changes. In addition, a measure of productivity can be calculated by relating the perceived value to the spent effort. This information is used in order to visualize the value propagation and performance during the development. Hence, through this method it is possible to evaluate the productivity of activities from initial ideas to a final product. The paper is concluded with a discussion of managerial implications and how this method contributes to theory.
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| 20. |
- Eynian, Mahdi, 1980-, et al.
(författare)
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New methods for in-process identification of modal parameters in milling
- 2018
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Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271 .- 2212-8271. ; 77, s. 469-472
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Tidskriftsartikel (refereegranskat)abstract
- Chatter vibrations encountered in machining can degrade surface finish and damage the machining hardware. Since chatter originates from unstable interaction of the machining process and the machining structure, information about vibration parameters of the machining structure should be used to predict combinations of cutting parameters that allow stable machining. While modal test methods, for example those with impact hammers, are widely used to identify structural parameters; the need for sophisticated test equipment is prohibitive in their use. Furthermore, dynamic properties of critical components of a machine tool may change as they get affected by cutting loads, material removal and spindle rotation. Recently few algorithms have been proposed that identify the in-process dynamic parameters by frequency measurements, thus avoiding these problems. In this paper, some of these algorithms are reviewed and their capabilities and limitations in processing am experimental data set are compared and discussed. © 2018 The Authors. Published by Elsevier Ltd.
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| 21. |
- Larsson, William, et al.
(författare)
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Coulometric Karl Fischer titration of trace water in diaphragm-free cells
- 2005
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 65:5, s. 1349-54
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Tidskriftsartikel (refereegranskat)abstract
- Factors influencing the accuracy and precision for diaphragm-free Karl Fischer coulometric determinations of low mu g-amounts of water have been studied using the Metrohm 756 (pulsed current) coulometer and eight different types of commercial coulometric reagents and some modifications of these. As in the case of diaphragm-free coulometric titration of large amounts of water, the positive errors, due to the formation of oxidizable reduction products (of sulfur dioxide) in the cathode reaction (besides hydrogen), were found to be minimized by the use of highest possible pulse current (in the range 100-400 mA) in combination with the fastest possible titration rate. Most accurate (102-103%) and precise results (typical relative standard deviation 1.8%) were obtained for reagents containing very large concentrations of imidazole in combination with the presence of modifiers like hexanol, chloroform and propylene glycol (i.e. the HYDRA-POINT reagents). Similar results were obtained when this type of reagent was mixed 60/40 with xylene according to the ASTM recommendation for water determinations in petroleum products like crude and lubricating oils. Addition of decanol to this type of reagent mixture was found to reduce the influence from the oxidative reduction products significantly. A reduction of the error from 3.6% relative to 1.6% was achieved by addition of 9% (v/v) of decanol to a 60/40 reagent mixture of HYDRA-POINT Coulometric Gen (containing hexanol as modifier) and xylene. For larger concentrations of decanol the pulse current had to be lowered to 100 mA and this might explain why no further improvement was observed. An additional attempt to minimize the interference by lowering the concentration of sulfur dioxide in the reagents gave no significant effect. However. by means of a home-built computer-controlled coulometric instrumentation based on continuous instead of pulsed current (including a large cathodic current density) it was possible to achieve recovery rates close to 100% for the best reagents investigated. The reason for this improvement is discussed.
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| 22. |
- Larsson, William, et al.
(författare)
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Efficiency of methods for Karl Fischer determination of water in oils based on oven evaporation and azeotropic distillation
- 2003
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 75:6, s. 1227-32
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of azeotropic distillation and oven evaporation techniques for trace determination of water in oils has recently been questioned by the National Institute of Standards and Technology (NIST), on the basis of measurements of the residual water found after the extraction step. The results were obtained by volumetric Karl Fischer (KF) titration in a medium containing a large excess of chloroform (> or = 65%), a proposed prerequisite to ensure complete release of water from the oil matrix. In this work, the extent of this residual water was studied by means of a direct zero-current potentiometric technique using a KF medium containing more than 80% chloroform, which is well above the concentration recommended by NIST. A procedure is described that makes it possible to correct the results for dilution errors as well as for chemical interference effects caused by the oil matrix. The corrected values were found to be in the range of 0.6-1.5 ppm, which should be compared with the 12-34 ppm (uncorrected values) reported by NIST for the same oils. From this, it is concluded that the volumetric KF method used by NIST gives results that are much too high.
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| 23. |
- Larsson, William, et al.
(författare)
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Interference-free coulometric titration of water in lithium bis(oxalato)borate using Karl Fischer reagents based on N-methylformamide
- 2006
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 69:1, s. 276-280
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Tidskriftsartikel (refereegranskat)abstract
- A non-alcoholic coulometric reagent based on N-methylformamide (NMF) was shown to eliminate the severe interference effect caused by the alcohol component of the conventional Karl Fischer (KF) reagent on the battery electrolyte lithium bis(oxalato)borate (LiBOB). For sample amounts up to 240 μg of water, the stoichiometry of the KF reaction deviated only slightly from the ideal 1:1 ratio for the best reagent composition. Both solid and dissolved (in acetonitrile, tetrahydrofuran (THF), and ethylene carbonate/ethyl methyl carbonate) LiBOB were titrated successfully using a Metrohm 756 KF Coulometer with a diaphragm cell. The detection limit was estimated to be 0.5–1 μg of water using 100 ml of reagent in this system.
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| 24. |
- Larsson, William, et al.
(författare)
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Investigation of Amine-Buffered Amide Reagents for Coulometric Karl Fischer Titration
- 2009
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Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 78:4-5, s. 1452-1457
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Tidskriftsartikel (refereegranskat)abstract
- Formamide (FA), N-methylformamide (NMF), and dimethylformamide (DMF),were evaluated as solvents for coulometric Karl Fischer (KF) reagents in combination with several amine bases. Except for the effect of the iodine species (iodine or triiodide), the pH of the reagent and the position of the sulfur dioxide/ hydrogen sulfite equilibrium were found to be the main factors explaining the large difference in the observed reaction rates betweenwater and the KF reagent in these solvents. Acid–base titrations showed that hydrogen sulfite is the main sulfur reactant in these media. The results will be of great importance in finding suitable combinations of base and solvent with respect to stoichiometry, side reactions caused by active carbonyl compounds, and reagent stability.
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| 25. |
- Larsson, William, 1975-
(författare)
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New approaches to moisture determination in complex matrices based on the Karl Fischer Reaction in methanolic and non-alcoholic media
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vattenhaltsbestämning är av stor vikt i många sammanhang. T.ex. kan vattenhalten påverka utbytet av en kemisk syntes, eller ha negativ inverkan på hållbarheten av läkemedel och livsmedel. Standardmetoden för vattenhaltsbestämning är Karl Fischer-titrering, baserad på antingen volymetri eller coulometri. I den här avhandlingen presenteras nya infallsvinklar för bestämning av mycket låga halter vatten i komplexa provmatriser, som t.ex. tekniska oljor och substanser som interfererar med alkoholbaserade Karl Fischer-reagens. Vattnet avskiljs ofta från oljematrisen före titrering genom förångning. I samband med framtagningen av nya referensmaterial för vatten i olja ifrågasattes förångningsteknikernas effektivitet av National Institute of Standards and Technology (NIST). NIST menade att en fraktion av vattnet bands hårt i oljefasen och att det inte kunde frigöras och detekteras annat än med en modifierad volymetrisk metod där reagenset innehöll minst 65% kloroform. I den här avhandlingen presenteras en alternativ metod som uppfyller det ställda kravet för en fullständig upplösning av oljefasen. Med denna metod visas att det inte finns någon anledning att ifrågasätta förångningsteknikernas effektivitet och att den modifierade metoden som NIST använder ger systematiskt för höga resultat. Fördelar som enklare handhavande, kortare konditioneringstider och att endast ett reagens behövs har gjort att diafragmafri coulometri har blivit allt mer populär. Spårhaltsbestämning med denna teknik ställer dock speciellt höga krav på reagensen eftersom strömtätheten vid katoden är låg. Med anledning av detta testades olika typer av kommersiella reagensblandningar för bestämning av små vattenmängder och kritiska parametrar identifierades. Dekanol visade sig ha en gynnsam effekt på katodreaktionen i reagens modifierade med xylen enligt standardmetodbeskrivningen för bestämning av vatten i oljor. För provtyper som inte går att analysera med alkoholbaserade reagenser presenteras en ny typ baserad på N-metylformamid. Med ett sådant reagens bestämdes vattenhalten i ett reaktivt salt som används i litiumjonbatterier. Liknande alkoholfria reagens undersöktes mer utförligt i en djupare studie som även inkluderade formamid och dimetylformamid. För- och nackdelar med dessa alternativa lösningsmedel diskuteras och möjliga reaktionsförlopp föreslås. Det visade sig att läget på jämvikten mellan svaveldioxid och vätesulfit är en avgörande faktor för att förklara den stora skillnaden i reaktionshastighet i dessa lösningsmedel.
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| 26. |
- Nguyen Van, Dong, 1971-
(författare)
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Speciation analysis of butyl- and phenyltin compounds in environmental samples by GC separation and atomic spectrometric detection
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main goal of the work presented in this thesis is to improve the reliability of existing methods for speciation analysis of organotin compounds Species-specific isotope dilution (SSID) calibration in combination with gas chromatography – inductively coupled plasma mass spectrometry was used to investigate the transformation of phenyltin species during sample preparation. Isotope-enriched phenyltin species were synthesized from corresponding isotope-enriched tin metals. SSID with a mixture of phenyltin species (PhTs) from one isotope was used to evaluate different extraction procedures for the determination of PhTs in fresh water sediment. Preparative liquid chromatography was used to produce single isotope-enriched phenyltin species making a multi-isotope spike (MI) SSID calibration possible. Different extraction procedures for the analysis of phenyltin species in biological samples were evaluated by applying MI-SSID. Degradation of TPhT and DPhT during sample extraction was observed and quantified. Accurate results were therefore obtained. A sample preparation procedure using mild extraction conditions with reasonable recoveries is described. The stability of organotin standards was investigated under different storage conditions. Mono- and diphenyltin were found to be redistributed and degraded during storage in methanol but were stabilized in sodium acetate/ acetic acid. A fast redistribution between monobutyl- and diphenyl tin has been observed and therefore it is therefore recommended that standards be derivatized as soon as possible after butyl- and phenyltin standards are mixed. Included in the thesis is also an investigation of the analytical potential of using instrumentation based on atomic absorption spectrometry (AAS) for speciation analysis of organotin compounds. The method was based on gas chromatographic separation, atomization in a quartz tube and detection by line source (LS) AAS and for comparison, by state of the art continuum source (CS) AAS. Analytical performances of CSAAS system were found to be better compared to LSAAS.
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| 27. |
- Nordmark, Ulrika, et al.
(författare)
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Conditions for Accurate Karl Fischer Coulometry Using Diaphragm-Free Cells
- 2000
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Ingår i: Analytical Chemistry. - Washington, D. C., USA : American Chemical Society. - 0003-2700 .- 1520-6882. ; 72:1, s. 172-179
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Tidskriftsartikel (refereegranskat)abstract
- Factors influencing the extent of formation of oxidizable reduction products in coulometric cells used for Karl Fischer (KF) determination of water were investigated. For methanolic KF reagents buffered with imidazole (Im) or diethanolamine (DEA) (separately or in combination), three parameters were found to be of outmost importance: the cathodic current density, the pH, and the concentration of protonated base (ImH+ or DEAH+). For reagents buffered with only Im, the relative formation of oxidizable reduction products varied in the range 2-40%; i.e., 51-70 g of water was found for a 50 g water sample, depending on the above-mentioned parameters. The lowest values were observed for reagents having a pH around 10 in combination with cathodic current densities in the range 2000-5000 mA cm-2. For all the Im-buffered reagents investigated, the addition of modifiers such as chloroform, hexanol, and carbon tetrachloride was found to decrease the formation of oxidizable reduction products significantly. For example, a reagent buffered at pH 10 containing 1 M hexanol gave less than 0.3% formation in the current density interval from 200 to 4000 mA cm-2. The best reagents based on the above-mentioned modifiers were tested in the continuous coulometric mode with errors typically in the interval 0-0.5% using optimum conditions. One prerequisite for obtaining such small errors with diaphragm-free continuous coulometry is to use a cathode area no larger than 0.002 cm2. For some of the reagents based on both Im and DEA, the formation of oxidizable reduction products was close to zero at certain current densities, although the analytical performance was not as good as for the reagents buffered solely by Im due to longer conditioning and titration times.
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| 28. |
- Nordmark, Ulrika, et al.
(författare)
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Optimum conditions for pulse generation in diaphragm-free Karl Fischer coulometry
- 2000
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Ingår i: Fresenius' Journal of Analytical Chemistry. - : Springer. - 0937-0633 .- 1432-1130. ; 368:5, s. 456-460
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Tidskriftsartikel (refereegranskat)abstract
- A flexible instrument was designed in order to investigate the influence of current magnitude, current duration and the frequency of the pulse generation on the error obtained in coulometric Karl Fischer titrations carried out in diaphragm-free cells. For a given current magnitude the lowest errors were obtained for current durations more than 60% of the total time for the pulse cycle. No significant influence of the pulse frequency (5-1000 Hz) was found independently of the pulse current duration for three different types of reagents intended fur diaphragm-free coulometry. For all reagents, the errors obtained with the home-built instrument were significantly smaller than those obtained with an optimized commercial titrator based on pulsed current generation. Using optimum conditions for the former instrument, in combination with an imidazole-buffered reagent at pH 10 containing chloroform as modifier, the accuracy was close to 100%. Thus, it is now possible to achieve the same high accuracy with diaphragm-free coulometry as with the conventional diaphragm based technique. The precision of the water determinations was affected by the size of the background.
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| 29. |
- Nordmark, Ulrika, et al.
(författare)
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Progress in pulsed-current Karl Fischer coulometry using diaphragm-free cells
- 2000
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Ingår i: Fresenius' Journal of Analytical Chemistry. - : Springer. - 0937-0633 .- 1432-1130. ; 367:6, s. 519-524
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Tidskriftsartikel (refereegranskat)abstract
- Factors influencing the accuracy of water determinations using diaphragm-free, pulsed current Karl Fischer (KF) coulometry were investigated with the new Metrohm 756 instrument. Results obtained with commercially available reagents from Riedel-deHaen and Merck were compared with home-made ones that were especially designed to minimize the formation of iodine-consuming reduction products generated in the cathode reaction. Positive errors in the range 2-5% were found for the commercial reagents as compared to 0.2-1% for the home-made ones which were buffered at about pH 10 containing modifiers like chloroform, hexanol or ethylene glycol. Except for the composition of the KF-reagent, the cathode current density and the titration rate were found to be critical parameters for the accuracy of the determinations. For all reagents investigated, the best results were obtained for the maximum generator current 400 mA (corresponding to a current density of 1400 mA cm(-2)) in combination with a maximum titration rate of 2000 mu g min(-1). Surprisingly, the errors found under optimum conditions for the pulse technique were always somewhat larger than the corresponding values obtained with continuous coulometry.
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| 30. |
- Pappila, Ove, et al.
(författare)
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Tid, rum rörlighet och position
- 2009
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Ingår i: Tankar om fälttåg. - Stockholm : Försvarshögskolan. - 9789189683174 ; , s. 163-185
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 31. |
- Shang, Ming-Mei, et al.
(författare)
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Lim domain binding 2 : a key driver of transendothelial migration of leukocytes and atherosclerosis
- 2014
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 34:9, s. 2068-2077
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Using a multi-tissue, genome-wide gene expression approach, we recently identified a gene module linked to the extent of human atherosclerosis. This atherosclerosis module was enriched with inherited risk for coronary and carotid artery disease (CAD) and overlapped with genes in the transendothelial migration of leukocyte (TEML) pathway. Among the atherosclerosis module genes, the transcription cofactor Lim domain binding 2 (LDB2) was the most connected in a CAD vascular wall regulatory gene network. Here, we used human genomics and atherosclerosis-prone mice to evaluate the possible role of LDB2 in TEML and atherosclerosis.APPROACH AND RESULTS: mRNA profiles generated from blood macrophages in patients with CAD were used to infer transcription factor regulatory gene networks; Ldlr(-/-)Apob(100/100) mice were used to study the effects of Ldb2 deficiency on TEML activity and atherogenesis. LDB2 was the most connected gene in a transcription factor regulatory network inferred from TEML and atherosclerosis module genes in CAD macrophages. In Ldlr(-/-)Apob(100/100) mice, loss of Ldb2 increased atherosclerotic lesion size ≈2-fold and decreased plaque stability. The exacerbated atherosclerosis was caused by increased TEML activity, as demonstrated in air-pouch and retinal vasculature models in vivo, by ex vivo perfusion of primary leukocytes, and by leukocyte migration in vitro. In THP1 cells, migration was increased by overexpression and decreased by small interfering RNA inhibition of LDB2. A functional LDB2 variant (rs10939673) was associated with the risk and extent of CAD across several cohorts.CONCLUSIONS: As a key driver of the TEML pathway in CAD macrophages, LDB2 is a novel candidate to target CAD by inhibiting the overall activity of TEML.
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| 32. |
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Tron är mitt lokalbatteri : religion och religiositet i August Strindbergs liv och verk
- 2012
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Tron är mitt lokalbatteri skriver August Strindberg i boken Ensam - ett av de sista verken. Tron tar sig många uttryck och strömkällan ger kraft till en mängd olika texter. Citatet ger en ingång till flera av dessa berättelser, och till berättelsen om Strindberg som sökare, mystiker, ateist och kristen. Bilden är mångskiftande.Till Damaskus, En Blå bok, Påsk, Mäster Olof, Giftasnovellerna, Sagospelen och Kammarspelen är några av de texter som betraktas ur detta perspektiv, men även hans tid i Frankrike, hans relation till den katolska kyrkan och till andra författare såsom Emanuel Swedenborg och Carl von Linne.Ett flertal författare och forskare som under lång tid arbetat med Strindbergs verk och liv medverkar. Avslutar gör biskop em Caroline Krook med en personlig betraktelse över det religiösa sökande som ses i August Strindbergs verk.
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| 33. |
- Wu, Jufang, 1972-
(författare)
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Modeling adsorption of organic compounds on activated carbon : a multivariate approach
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Activated carbon is an adsorbent that is commonly used for removing organic contaminants from air due to its abundant pores and large internal surface area. This thesis is concerned with the static adsorption capacity and adsorption kinetics for single and binary organic compounds on different types of activated carbon. These are important parameters for the design of filters and for the estimation of filter service life. Existing predictive models for adsorption capacity and kinetics are based on fundamental “hard” knowledge of adsorption mechanisms. These models have several drawbacks, especially in complex situations, and extensive experimental data are often needed as inputs. In this work we present a systematic approach that can contribute to the further development of predictive models, especially for complex situations. The approach is based on Multivariate Data Analysis (MVDA), which is ideally suited for the development of soft models without incorporating any assumptions about the mathematical form or fundamental physical principles involved.Adsorption capacity and adsorption kinetics depend on the properties of the carbon and the adsorbate as well as experimental conditions. Therefore, to make general statements regarding adsorption capacity and kinetics it is important for the resulting models to be representative of the conditions they will simulate. Accordingly, the first step in the investigations underlying this thesis was to select a minimum number of representative and chemically diverse organic compounds. The next steps were to study the dependence of the derived affinity coefficient, β, in the Dubinin-Radushkevich equation on properties of organic compounds and to establish a new, improved model. This new model demonstrates the importance of adding descriptors for the specific interaction with the carbon surface to the size and shape descriptors. The adsorption capacities of the same eight organic compounds at low relative pressures were correlated with compound properties. It was found that different compound properties are important in the various stages of adsorption, reflecting the fact that different mechanisms are involved. Ideal adsorbed solution theory (IAST) in combination with the Freundlich equation was developed to predict the adsorption capacities of binary organic compound mixtures. A new model was proposed for predicting the rate coefficient of the Wheeler-Jonas equation which is valid for breakthrough ratios up to 20%. Finally, it was shown that the Wheeler-Jonas equation can be adapted to describe the breakthrough curves of binary mixtures. New models were proposed for predicting its parameters, the adsorption rate coefficients, and the adsorption capacities for both components of the binary mixture. Thus, multivariate data analysis can not only be used to assist in the understanding of adsorption mechanisms, but also contribute to the development of predictive models of adsorption capacity and breakthrough time for single and binary organic compounds.
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