| 1. |
- Al-Emrani, Mohammad, 1967, et al.
(författare)
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Girders with Trapezoidally Corrugated Webs -- Under Patch Loading
- 2011
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Ingår i: EUROSTEEL 2011. - 9789291471034 ; 2, s. 620-625
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the buckling and postbuckling behaviour of plate girders with corrugated web under a concentrated load on the top flange. A couple of design models and experiments from earlier studies are briefly reviewed.Further, six additional experimental tests have been performed on a girder with thin corrugated web. A FE-model of this girder is then developed and the behaviour of the girder is validated through comparisons with the girder used in the tests. The ultimate load and the postbuckling behaviour were determined by both laboratory tests and finite element simulations for three different positions of a narrow load strip across the flange, namely at: (1) an inclined fold, (2) the junction between two folds, (3) a longitudinal fold. Finally, a parametric study is performed using the FE-model where the influence of certain parameters on the ultimate load and buckling behaviour is investigated. The results from this parametric study are compared and evaluated together with two design models chosen to be the most suitable.
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| 2. |
- Alm, Erik, 1980-, et al.
(författare)
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Vibrational overtone combination spectroscopy (VOCSY)—a new way of using IR and NIR data
- 2007
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 388:1, s. 179-188
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Tidskriftsartikel (refereegranskat)abstract
- This work explores a novel method for rearranging 1st order (one-way) infra-red (IR) and/or near infra-red (NIR) ordinary spectra into a representation suitable for multi-way modelling and analysis. The method is based on the fact that the fundamental IR absorption and the first, second, and consecutive overtones of NIR absorptions represent identical chemical information. It is therefore possible to rearrange these overtone regions of the vectors comprising an IR and NIR spectrum into a matrix where the fundamental, 1st, 2nd, and consecutive overtones of the spectrum are arranged as either rows or columns in a matrix, resulting in a true three-way tensor of data for several samples. This tensorization facilitates explorative analysis and modelling with multi-way methods, for example parallel factor analysis (PARAFAC), N-way partial least squares (N-PLS), and Tucker models. The vibrational overtone combination spectroscopy (VOCSY) arrangement is shown to benefit from the “order advantage”, producing more robust, stable, and interpretable models than, for example, the traditional PLS modelling method. The proposed method also opens the field of NIR for true peak decomposition—a feature unique to the method because the latent factors acquired using PARAFAC can represent pure spectral components whereas latent factors in principal component analysis (PCA) and PLS usually do not.
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| 3. |
- Andersch-Björkman, Ylva, et al.
(författare)
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Air-oxidized linalool elicits eczema in allergic patients-a repeated open application test study.
- 2014
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Ingår i: Contact dermatitis. - : Wiley. - 1600-0536 .- 0105-1873. ; 70:3, s. 129-38
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Tidskriftsartikel (refereegranskat)abstract
- Linalool is a commonly used fragrance terpene that forms potent sensitizers upon oxidation. In a recent multicentre study, we found that 7% of 2900 patients showed positive patch test reactions to oxidized linalool at 6.0%. No elicitation studies have been performed.
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| 4. |
- Bodén, Ida, 1977-
(författare)
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Near infrared and skin impedance spectroscopic in vivo measurements on human skin : development of a diagnostic tool for skin cancer
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Every year approximately 2800 Swedes are diagnosed with malignant melanoma, the form of cancer that is most rapidly increasing in incidence in the Western world. The earlier we can identify and diagnose a malignant melanoma, the better is the prognosis. In Sweden, 155 000 benign naevi, harmless skin tumours or moles, are surgically excised each year, many of them because melanoma cannot be dismissed by non-invasive methods. The excisions result in substantial medical costs and cause unrest and suffering of the individual patient. For untrained physicians, it is often difficult to make an accurate diagnosis of melanoma, thus a tool that could help to strengthen the diagnosis of suspected melanomas would be highly valuable. This thesis describes the development and assessment of a non-invasive method for early skin cancer detection. Using near infrared (NIR) and skin impedance spectroscopy, healthy and diseased skin of various subjects was examined to develop a new instrument for detecting malignant melanoma. Due to the complex nature of skin and the numerous variables involved, the spectroscopic data were analysed multivariately using Principal Component Analysis (PCA) and partial leas square discriminant analysis (PLS-DA). The reproducibility of the measurements was determined by calculating Scatter Values (SVs), and the significance of separations between overlapping groups in score plots was determined by calculating intra-model distances. The studies indicate that combining skin impedance and NIR spectroscopy measurements adds value, therefore a new probe-head for simultaneous NIR and skin impedance measurements was introduced. Using both spectroscopic techniques it was possible to separate healthy skin at one body location from healthy skin at another location due to the differences in skin characteristics at various body locations. In addition, statistically significant differences between overlapping groups of both age and gender in score plots were detected. However, the differences in skin characteristics at different body locations had stronger effects on the measurements than both age and gender. Intake of coffee and alcohol prior to measurement did not significantly influence the outcome data. Measurements on dysplastic naevi were significantly separated in a score plot and the influence of diseased skin was stronger than that of body location. This was confirmed in a study where measurements were performed on 12 malignant melanomas, 19 dysplastic naevi and 19 benign naevi. The malignant melanomas were significantly separated from both dysplastic naevi and benign naevi. Overall, the presented findings show that the instrument we have developed provides fast, reproducible measurements, capable of distinguishing malignant melanoma from dysplastic naevi and benign naevi non-invasively with 83% sensitivity and 95% specificity. Thus, the results are highly promising and the instrument appears to have high potential diagnostic utility.
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| 5. |
- Claeson Bohnstedt, Kristina, 1974-
(författare)
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Determination of biomarkers for lipid peroxidation and oxidative stress : Development of analytical techniques and methods
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oxidative stress can be defined as a state of disturbance in the pro-oxidant/antioxidant balance in favour of the former, leading to potential damage. Processes associated with oxidative stress involve reactive oxygen species and radicals and can result in elevated levels of oxidatively modified or toxic molecules that can cause cellular malfunction, and even cell death. Destruction of membrane lipids, lipid peroxidation, caused by reactive oxygen species and radicals has been coupled to many diseases and also normal ageing. The measurement of low molecular weight biomarkers of oxidative stress present in complex matrices such as brain tissue, plasma, urine or cerebrospinal fluid is a delicate and difficult task and there is a need for improved analytical tools in this field of research. The major foci of this thesis and the work underlying it are the development of analytical techniques and methods for determining biomarkers for oxidative stress and lipid peroxidation. Aspects of particular concern include the effects of sample treatments prior to analysis, evaluation of the developed methods with respect to possible artefacts, and the scope for results to be misinterpreted. The specific research goals and issues addressed are detailed in five papers, which this thesis is based upon.Paper I focuses on malondialdehyde, describing and evaluating two new simplified sample pre-treatment regimes for the determination of malondialdehyde in rat brain tissue by capillary electrophoresis with UV detection. The effects of sample storing and handling are also considered.Paper II describes the synthesis, characterization and implementation of a new internal standard for the determination of malondialdehyde in biological samples using electrophoretic or chromatographic separation techniques. The usefulness of the internal standard is demonstrated in analyses of rat brain tissue samples.Paper III presents a method for the determination of 4-hydroxynon-2-enal in brain tissue from rats employing micellar electrokinetic chromatography separation and laser-induced fluorescence detection. Paper IV is focused on the development of a new methodology for determining the stereoisomeric F2-isoprostanes in human urine samples employing chromatographic separation on porous graphitic carbon and detection by electrospray ionization-tandem mass spectrometry. The results from this study conflict with the hypothesis that peripheral isoprostanes are elevated in patients with Alzheimer’s disease.Paper V describes porous graphitic carbon chromatography-tandem mass spectrometry for the determination of isoprostanes in human cerebrospinal fluid. A new simplified sample pre-treatment regime, involving a column switching technique, is presented that allows direct injection of a relatively large volume of CSF into the chromatographic system.
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| 6. |
- Claeson Bohnstedt, Kristina, et al.
(författare)
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Porous graphitic carbon chromatography-tandem mass spectrometry for the detection of isoprostanes in human cerebrospinal fluid
- 2005
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 827:1, s. 39-43
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Tidskriftsartikel (refereegranskat)abstract
- F2-isoprostanes are produced by the non-enzymatic peroxidation of arachidonic acid in membrane phospholipids. This paper describes a new method for the determination of all four classes of F2-isoprostanes in human cerebrospinal fluid (CSF) involving separation on a 1 mm × 150 mm porous graphitic carbon (PGC) column and detection by triple quadrupole mass spectrometry in negative-ion electrospray mode. The sample pre-treatment consisted of an ultrafiltration step, following which 300 μl of CSF sample could be injected directly onto a 1 mm × 10 mm PGC guard column functioning as a trap for the analytes. The loading solvent was Milli-Q water at 125 μl/min. After 3 min, the sample was switched into the separation column. The F2-isoprostanes were separated in 20 min using a linear solvent gradient comprising water, methanol, acetonitrile and ammonium hydroxide at a pH of 9.5 and a flow of 50 μl/min The limit of detection (calculated as 3S/N) was approximately 40 pM (14 pg/ml). The assay was linear within the examined range (18–450 pg/ml), using CSF spiked with iPF2α-III standard (r2 > 0.995). Repeatability data were calculated for CSF spiked to 90 pg/ml and the relative standard deviation (RSD) obtained was 3% (n = 6).
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| 9. |
- Ericsson, Olle, et al.
(författare)
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Clinical validation of a novel automated cell-free DNA screening assay for trisomies 21, 13, and 18 in maternal plasma.
- 2019
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Ingår i: Prenatal diagnosis. - : Wiley. - 1097-0223 .- 0197-3851. ; 39:11, s. 1011-1015
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate clinical performance of a new automated cell-free (cf)DNA assay in maternal plasma screening for trisomies 21, 18, and 13, and to determine fetal sex.Maternal plasma samples from 1200 singleton pregnancies were analyzed with a new non-sequencing cfDNA method, which is based on imaging and counting specific chromosome targets. Reference outcomes were determined by either cytogenetic testing, of amniotic fluid or chorionic villi, or clinical examination of neonates.The samples examined included 158 fetal aneuploidies. Sensitivity was 100% (112/112) for trisomy 21, 89% (32/36) for trisomy 18, and 100% (10/10) for trisomy 13. The respective specificities were 100%, 99.5%, and 99.9%. There were five first pass failures (0.4%), all in unaffected pregnancies. Sex classification was performed on 979 of the samples and 99.6% (975/979) provided a concordant result.The new automated cfDNA assay has high sensitivity and specificity for trisomies 21, 18, and 13 and accurate classification of fetal sex, while maintaining a low failure rate. The study demonstrated that cfDNA testing can be simplified and automated to reduce cost and thereby enabling wider population-based screening.
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| 10. |
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