oru.sePublikationer
Change search
Refine search result
2930313233 1551 - 1600 of 1617
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1551.
    Westerlund, Jessica
    et al.
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
    Graff, Pål
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
    Bryngelsson, Ing-Liss
    Department of Occupational and Environmental Medicine, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Westberg, Håkan
    Örebro University, School of Science and Technology.
    Eriksson, Kåre
    Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine, Umeå University, Umeå, Sweden.
    Löfstedt, Håkan
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
    Occupational Exposure to Trichloramine and Trihalomethanes in Swedish Indoor Swimming Pools: Evaluation of Personal and Stationary Monitoring2015In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 59, no 8, 1074-1084 p.Article in journal (Refereed)
    Abstract [en]

    Introduction: Chlorination is a method commonly used to keep indoor swimming pool water free from pathogens. However, chlorination of swimming pools produces several potentially hazardous by-products as the chlorine reacts with nitrogen containing organic matter. Up till now, exposure assessments in indoor swimming pools have relied on stationary measurements at the poolside, used as a proxy for personal exposure. However, measurements at fixed locations are known to differ from personal exposure.

    Methods: Eight public swimming pool facilities in four Swedish cities were included in this survey. Personal and stationary sampling was performed during day or evening shift. Samplers were placed at different fixed positions around the pool facilities, at similar to 1.5 m above the floor level and 0-1 m from the poolside. In total, 52 personal and 110 stationary samples of trichloramine and 51 personal and 109 stationary samples of trihalomethanes, were collected.

    Results: The average concentration of trichloramine for personal sampling was 71 mu g m(-3), ranging from 1 to 240 mu g m(-3) and for stationary samples 179 mu g m(-3), ranging from 1 to 640 mu g m(-3). The air concentrations of chloroform were well below the occupational exposure limit (OEL). For the linear regression analysis and prediction of personal exposure to trichloramine from stationary sampling, only data from personal that spent > 50% of their workday in the pool area were included. The linear regression analysis showed a correlation coefficient (r (2)) of 0.693 and a significant regression coefficient beta of 0.621; (95% CI = 0.329-0.912, P = 0.001).

    Conclusion: The trichloramine exposure levels determined in this study were well below the recommended air concentration level of 500 mu g m(-3); a WHO reference value based on stationary sampling. Our regression data suggest a relation between personal exposure and area sampling of 1:2, implying an OEL of 250 mu g m(-3) based on personal sampling.

  • 1552.
    Westling, Magnus
    Örebro University, School of Science and Technology. Örebro University, School of Hospitality, Culinary Arts & Meal Science.
    Microbial processes and volatile metabolites in cheese: detection of bacteria using an electronic nose2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Cheese is a fermented product in which bacteria contribute to different flavours and textures. In order to understand the microbial processes in cheese, it is necessary to not only look at the genomic information in bacteria. The metabolome consists of a complete collection of metabolites in a biological sample. These metabolites are small molecules with a Mr >1.5 kDa, including flavour compounds. During the ripening process of cheese, many microbiological and biochemical changes occur that give cheese a diversity of textures and flavours. Proteins that go through proteolysis and amino acid catabolism are of great importance in the development of flavour in cheese, regardless of variety. Even though techniques for measurements of metabolites have existed for a long time, there are some unique challenges by analysing of several metabolites in parallel in a biological sample that promotes different metabolic pathways. Metabolic fingerprinting is the most common approach used in metabolomics, which is based on statistical analysis that through algorithms presents differences between samples. The electronic nose is able to identify the sum of volatile metabolites in a food, which is unlike the gas chromatograph that identifies individual metabolites. The aim of this review is to evaluate the use of metabolomics of selected Enterobacteriaceae together with electronic nose technology in order to analyse possible patterns of volatile metabolites produced in soft cheese. By this we hope to evaluate potential application of this approach in food quality control and microbial contamination screening. The pilot study was done together with the center for AASS, Örebro University where bacteria were analysed using the electronic nose NST3320. The study showed that it is possible to discriminate between Enterobacteriaceae, Staphylococcus aureus and cheese-associated bacteria, but also between the Enterobacteriaceae species Escherichia coli, Hafnia alvei and Klebsiella pneumoniae. It is important to consider the gas sensors gradually lose their ability to detect substances after continual use, in which they need to be replaced with new gas sensors. Further, data processing requires special knowledge and can be hard to handle if the expertise is lacking. We believe that there is evidence that metabolomics together with the electronic nose have future prospects in terms of quality control and microbial contamination screening.

  • 1553.
    Westling, Magnus
    Örebro University, School of Science and Technology.
    Microbial Processes and Volatile Metabolites in Cheese Detection of Bacteria Using an Electronic Nose2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Cheese is a fermented product in which bacteria contribute to different flavours and textures. In order to understand the microbial processes in cheese, it is necessary to not only look at the genomic information in bacteria. The metabolome consists of a complete collection of metabolites in a biological sample. These metabolites are small molecules with a Mr >1.5 kDa, including flavour compounds. During the ripening process of cheese, many microbiological and biochemical changes occur that give cheese a diversity of textures and flavours. Proteins that go through proteolysis and amino acid catabolism are of great importance in the development of flavour in cheese, regardless of variety. Even though techniques for measurements of metabolites have existed for a long time, there are some unique challenges by analysing of several metabolites in parallel in a biological sample that promotes different metabolic pathways. Metabolic fingerprinting is the most common approach used in metabolomics, which is based on statistical analysis that through algorithms presents differences between samples. The electronic nose is able to identify the sum of volatile metabolites in a food, which is unlike the gas chromatograph that identifies individual metabolites. The aim of this review is to evaluate the use of metabolomics of selected Enterobacteriaceae together with electronic nose technology in order to analyse possible patterns of volatile metabolites produced in soft cheese. By this we hope to evaluate potential application of this approach in food quality control and microbial contamination screening. The pilot study was done together with the center for AASS, Örebro University where bacteria were analysed using the electronic nose NST3320. The study showed that it is possible to discriminate between Enterobacteriaceae, Staphylococcus aureus and cheese-associated bacteria, but also between the Enterobacteriaceae species Escherichia coli, Hafnia alvei and Klebsiella neumoniae. It is important to consider the gas sensors gradually lose their ability to detect substances after continual use, in which they need to be replaced with new gas sensors. Further, data processing requires special knowledge and can be hard to handle if the expertise is lacking. We believe that there is evidence that metabolomics together with the electronic nose have future prospects in terms of quality control and microbial contamination screening.

  • 1554.
    Westling, Magnus
    et al.
    Örebro University, School of Hospitality, Culinary Arts & Meal Science.
    Danielsson Tham, Marie-Louise
    Örebro University, School of Hospitality, Culinary Arts & Meal Science.
    Jass, Jana
    Örebro University, School of Science and Technology.
    Nilsen, Asgeir
    Örebro University, School of Hospitality, Culinary Arts & Meal Science.
    Öström, Åsa
    Örebro University, School of Hospitality, Culinary Arts & Meal Science.
    Tham, Wilhelm
    Örebro University, School of Hospitality, Culinary Arts & Meal Science.
    Contribution of Enterobacteriaceae to Sensory Characteristics in Soft Cheeses Made from Raw Milk2016In: Procedia Food Science, ISSN 2211-601X, E-ISSN 2211-601X, Vol. 7, 17-20 p.Article in journal (Refereed)
    Abstract [en]

    Microbiological and sensory methods were used to analyze 22 soft cheeses, of which 19 were made from raw milk, one was made from both raw and pasteurized milk and two were made from pasteurized milk. Moderate correlations (r-value 0.5–0.6 and p-value <0.01–0.05) were found between the levels of Enterobacteriaceae 37°C and the intensity of the sensory characteristics “bitter”, “metallic”, “pungent”, “manure” and “ammonia”. The present study indicates that it is possible to predict high levels of Enterobacteriaceae in soft cheeses made from raw milk using only the human senses (odor and taste).

  • 1555.
    Westman, Ola
    Örebro University, School of Science and Technology.
    Development of bioassays for risk assessment of PAHs and PFASs in the environment2013Doctoral thesis, comprehensive summary (Other academic)
    List of papers
    1. Perfluorooctane sulfonate increases β-oxidation of palmitic acid in chicken liver
    Open this publication in new window or tab >>Perfluorooctane sulfonate increases β-oxidation of palmitic acid in chicken liver
    2012 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 19, no 5, 1859-1863 p.Article in journal (Refereed) Published
    Abstract [en]

    Purpose: Perfluorooctane sulfonate (PFOS) belongs to a group of chemicals called perfluoroalkyl acids that have been extensively used in various applications such as stain and oil resistant treatments for fabrics, fire-fighting foams, and insecticides. These chemicals present an environmental and health risk being present in many samples both in wildlife and humans. In this study, we investigate the effect of PFOS on fatty acid β-oxidation in developing chicken embryos.

    Methods: Fertilized chicken eggs were exposed in ovo to PFOS at day 4 of incubation. On day 10, the eggs were dissected and livers were incubated in vitro with (3)H-palmitic acid for 2 h. The media were collected, and after clean up, the amount of tritiated water was measured with liquid scintillation counting to determine the rate of palmitic acid β-oxidation.

    Results: PFOS was found to induce fatty acid β-oxidation at doses starting from a lowest observed effect level (LOEL) of 0.1 μg/g egg weight. Maximum induction of 77 % compared to control was seen at 0.3 μg/g.

    Conclusions: The administered doses in which effects are seen are around and even lower than the levels that can be found in wild populations of birds. General population human levels are a factor of two to three times lower than the LOEL value of this study. The environmental contamination of PFOS therefore presents a possibility of effects in wild populations of birds.

    Place, publisher, year, edition, pages
    Heidelberg, Germany: Springer Berlin/Heidelberg, 2012
    Keyword
    Perfluorooctane sulfonate, PFOS, exposure, chicken, palmitic acid, β-oxidation, tritium
    National Category
    Medical and Health Sciences Biological Sciences Biomedical Laboratory Science/Technology
    Research subject
    Biology; Biomedical Laboratory Science
    Identifiers
    urn:nbn:se:oru:diva-24853 (URN)10.1007/s11356-012-0869-1 (DOI)000305884600053 ()22441698 (PubMedID)2-s2.0-84863225035 (Scopus ID)
    Funder
    Swedish Research Council Formas
    Available from: 2012-08-23 Created: 2012-08-23 Last updated: 2017-10-17Bibliographically approved
    2. Polycyclic aromatic hydrocarbons (PAHs) reduce hepatic beta-oxidation of fatty acids in chick embryos
    Open this publication in new window or tab >>Polycyclic aromatic hydrocarbons (PAHs) reduce hepatic beta-oxidation of fatty acids in chick embryos
    Show others...
    2013 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 20, no 3, 1881-1888 p.Article in journal (Refereed) Published
    Abstract [en]

    Polycyclic aromatic hydrocarbons (PAHs) are widespread fused-ring contaminants formed during incomplete combustion of almost all kind of organic materials from both natural and anthropogenic sources. Some PAHs have been shown to be carcinogenic to humans, and a wide range of PAHs are found in wildlife all around the globe including avian species. The purpose of this project was to assess the effects of a standard mixture of 16 PAHs (United States Environmental Protection Agency) on the hepatic fatty acid beta-oxidation in chicken embryos (Gallus gallus domesticus) exposed in ovo. The hepatic beta-oxidation was measured using a tritium release assay with [9,10-H-3]-palmitic acid (16:0) as substrate. Treated groups were divided into groups of 0.05, 0.1, 0.3, 0.5, and 0.8 mg PAHs/kg egg weight. The hepatic beta-oxidation was reduced after exposure in ovo to the 16 PAHs mixture compared to control. The mechanisms causing reduced fatty acid oxidation in the present study are unclear, however may be due to deficient membrane structure, the functionality of enzymes controlling the rate of fatty acid entering into the mitochondria, or complex pathways connected to endocrine disruption. To the best of our knowledge, this is the first time a PAH-caused reduction of hepatic beta-oxidation of fatty acids in avian embryos has been observed. The implication of this finding on risk assessment of PAH exposure in avian wildlife remains to be determined.

    National Category
    Natural Sciences
    Research subject
    Enviromental Science; Biology
    Identifiers
    urn:nbn:se:oru:diva-29081 (URN)10.1007/s11356-012-1418-7 (DOI)000315442500065 ()23274806 (PubMedID)
    Projects
    SOILTOX
    Funder
    Knowledge Foundation
    Available from: 2013-05-21 Created: 2013-05-21 Last updated: 2017-10-17Bibliographically approved
    3. An oxygenated metabolite of benzo[a]pyrene increases hepatic β-oxidation of fatty acids in chick embryos
    Open this publication in new window or tab >>An oxygenated metabolite of benzo[a]pyrene increases hepatic β-oxidation of fatty acids in chick embryos
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Biological Sciences Environmental Biotechnology
    Research subject
    Biology; Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-33946 (URN)
    Available from: 2014-02-26 Created: 2014-02-26 Last updated: 2017-10-17Bibliographically approved
    4. Comparative study and characterization of mutagenicity and AhR-agonistic potency of contaminated soil, remediated soil, urban city soil and rural soil
    Open this publication in new window or tab >>Comparative study and characterization of mutagenicity and AhR-agonistic potency of contaminated soil, remediated soil, urban city soil and rural soil
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Current risk assessment of PAH-contaminated soils is usually based on chemical analysis of a small number of PAHs. The use of effect-based methods for risk assessment would yield results covering more of the effect of all the chemicals in the soil. To put such effect based data into context we tested a relative approach in which effects of contaminated soil were compared to clean rural and urban soils. This concept of relative risk assessment was tested by studying the mutagenic and AhR-agonistic potency of contaminated soil and urban soil compared to farm soil from selected ecological farms. A set of 21 soil samples was collected: 11 PAH-contaminated samples (collected in collaboration with three Swedish remediation companies), 5 urban samples (collected in Swedish cities) and 5 soil samples from ecological farms. The urban and rural samples were collected at the surface (0-10 cm deep), the contaminated samples were collected from piles during remediation (100-200 cm deep). To evaluate the toxicants in the soil sample, lipophilic sample extracts were tested in two different assays; (i) the Ames Fluctuation Assay (AFA) mutant strains TA98 and TA100 of Salmonella typhimurium with and without a metabolic activation system (rat-liver homogenate S9) to determine the mutagenic potential of the soil samples and (ii) the cell mechanism-specific H4IIE-luc assay to determine the Ahreceptor (AhR) activating potency of the soil extracts. The results showed clear mutagenicity, both direct and indirect, in one of the PAH-contaminated samples and three other PAH samples also demonstrated some mutagenic activity. The extracts from urban city soil showed mutagenicity in three of the 5 samples, while none of the ecological farm samples had mutagenic extracts. The bio-TEQ values were very high for all remediated samples and elevated in one urban sample. Bio-TEQ values were low in the ecological farm extracts. These findings demonstrate that the present investigation scheme using two different bioassays to determine the mutagenic potential and the Ah receptor activating potency of soil extracts is a suitable method for testing toxic properties of soil extracts. The concept of relative risk assessment using background samples from rural and urban areas and effect based testing shows promise for further development.

    Keyword
    contaminated soil; genotoxicity; AhR-inducing; bioassay, toxicity
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-33947 (URN)
    Available from: 2014-02-26 Created: 2014-02-26 Last updated: 2017-10-17Bibliographically approved
  • 1556.
    Westman, Ola
    et al.
    Örebro University, School of Science and Technology.
    Larsson, Maria
    Örebro University, School of Science and Technology.
    Hollert, Henner
    2RWTH Aachen University, Inst. For Environmental Research, Department of Ecosystem Analysis, Aachen, Germany.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    Comparative study and characterization of mutagenicity and AhR-agonistic potency of contaminated soil, remediated soil, urban city soil and rural soilManuscript (preprint) (Other academic)
    Abstract [en]

    Current risk assessment of PAH-contaminated soils is usually based on chemical analysis of a small number of PAHs. The use of effect-based methods for risk assessment would yield results covering more of the effect of all the chemicals in the soil. To put such effect based data into context we tested a relative approach in which effects of contaminated soil were compared to clean rural and urban soils. This concept of relative risk assessment was tested by studying the mutagenic and AhR-agonistic potency of contaminated soil and urban soil compared to farm soil from selected ecological farms. A set of 21 soil samples was collected: 11 PAH-contaminated samples (collected in collaboration with three Swedish remediation companies), 5 urban samples (collected in Swedish cities) and 5 soil samples from ecological farms. The urban and rural samples were collected at the surface (0-10 cm deep), the contaminated samples were collected from piles during remediation (100-200 cm deep). To evaluate the toxicants in the soil sample, lipophilic sample extracts were tested in two different assays; (i) the Ames Fluctuation Assay (AFA) mutant strains TA98 and TA100 of Salmonella typhimurium with and without a metabolic activation system (rat-liver homogenate S9) to determine the mutagenic potential of the soil samples and (ii) the cell mechanism-specific H4IIE-luc assay to determine the Ahreceptor (AhR) activating potency of the soil extracts. The results showed clear mutagenicity, both direct and indirect, in one of the PAH-contaminated samples and three other PAH samples also demonstrated some mutagenic activity. The extracts from urban city soil showed mutagenicity in three of the 5 samples, while none of the ecological farm samples had mutagenic extracts. The bio-TEQ values were very high for all remediated samples and elevated in one urban sample. Bio-TEQ values were low in the ecological farm extracts. These findings demonstrate that the present investigation scheme using two different bioassays to determine the mutagenic potential and the Ah receptor activating potency of soil extracts is a suitable method for testing toxic properties of soil extracts. The concept of relative risk assessment using background samples from rural and urban areas and effect based testing shows promise for further development.

  • 1557.
    Westman, Ola
    et al.
    Örebro University, School of Science and Technology. Structor Miljöteknik AB, Örebro, Sweden.
    Larsson, Maria
    Örebro University, School of Science and Technology.
    Venizelos, Nikolaos
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
    Hollert, Henner
    Institute for Environmental Research, Department of Ecosystem Analysis, RWTH Aachen University, Aachen, Germany.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    An oxygenated metabolite of benzo[a]pyrene increases hepatic beta-oxidation of fatty acids in chick embryos2014In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 21, no 9, 6243-6251 p.Article in journal (Refereed)
    Abstract [en]

    Polycyclic aromatic hydrocarbons (PAHs) are well-known carcinogens to humans and ecotoxicological effects have been shown in several studies. However, PAHs can also be oxidized into more water soluble-oxygenated metabolites (Oxy-PAHs). The first purpose of the present project was to (1) assess the effects of a mixture containing three parent PAHs: anthracene, benz[a]anthracene, and benzo[a]pyrene versus a mixture of their oxygenated metabolites, namely: anthracene-9,10-dione, benz[a]anthracene-7,12-dione, and 9,10-dihydrobenzo[a]pyrene-7-(8H)-one on the hepatic fatty acid beta-oxidation in chicken embryos (Gallus gallus domesticus) exposed in ovo. The second and also main purpose of the project was to (2) assess the effects of the parent PAHs versus their oxy-PAHs analogues when injected individually, followed by (3) additional testing of the individual oxy-PAHs. The hepatic beta-oxidation was measured using a tritium release assay with [9,10-H-3]-palmitic acid (16:0) as substrate. The result from the first part (1) showed reduced hepatic beta-oxidation after exposure in ovo to a mixture of three PAHs, however, increased after exposure to the mixture of three oxy-PAHs compared to control. The result from the second part (2) and also the follow-up experiment (3) showed that 9,10-dihydrobenzo[a]pyrene-7-(8H)-one was the causative oxy-PAH. The implication of this finding on the risk assessment of PAH metabolite exposure in avian wildlife remains to be determined. To the best of our knowledge, no similar studies have been reported.

  • 1558.
    Westman, Ola
    et al.
    Örebro University, School of Science and Technology.
    Larsson, Maria
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
    Venizelos, Nikolaos
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
    Hollert, Henner
    3RWTH Aachen University, Inst. For Environmental Research, Department of Ecosystem Analysis, Aachen, Germany.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    An oxygenated metabolite of benzo[a]pyrene increases hepatic β-oxidation of fatty acids in chick embryosManuscript (preprint) (Other academic)
  • 1559.
    Westman, Ola
    et al.
    Örebro University, School of Science and Technology.
    Nordén, Marcus
    Örebro University, School of Science and Technology.
    Larsson, Maria
    Örebro University, School of Science and Technology.
    Venizelos, Nikolaos
    Örebro University, School of Science and Technology.
    Hollert, Henner
    RWTH Aachen University, Germany.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    Reduced beta-oxidation in avian following exposure of polycyclic aromatic hydrocarbons2012In: Toxicology Letters, ISSN 0378-4274, E-ISSN 1879-3169, Vol. 211, no Supplement, s86-s87 p.Article in journal (Refereed)
  • 1560.
    Wiedemann, Thomas
    et al.
    Institute of Communications and Navigation German Aerospace Center (DLR), Wessling, Germany.
    Shutin, Dmitri
    Institute of Communications and Navigation German Aerospace Center (DLR), Wessling, Germany.
    Hernandez Bennetts, Victor
    Örebro University, School of Science and Technology.
    Schaffernicht, Erik
    Örebro University, School of Science and Technology.
    Lilienthal, Achim
    Örebro University, School of Science and Technology.
    Bayesian Gas Source Localization and Explorationwith a Multi-Robot System Using PartialDifferential Equation Based Modeling2017In: 2017 ISOCS/IEEE International Symposium on Olfaction and Electronic Nose (ISOEN 2017): Proceedings, 2017, 122-124 p.Conference paper (Refereed)
    Abstract [en]

    Here we report on active water sampling devices forunderwater chemical sensing robots. Crayfish generate jetlikewater currents during food search by waving theflagella of their maxillipeds. The jets generated toward theirsides induce an inflow from the surroundings to the jets.Odor sample collection from the surroundings to theirolfactory organs is promoted by the generated inflow.Devices that model the jet discharge of crayfish have beendeveloped to investigate the effectiveness of the activechemical sampling. Experimental results are presented toconfirm that water samples are drawn to the chemicalsensors from the surroundings more rapidly by using theaxisymmetric flow field generated by the jet discharge thanby centrosymmetric flow field generated by simple watersuction. Results are also presented to show that there is atradeoff between the angular range of chemical samplecollection and the sample collection time.

  • 1561.
    Wigh, Viktoria
    Örebro University, School of Science and Technology.
    Metabolomic study of the effects of perfluorinated compounds on the fatty acid metabolism during the development of Gallus gallus domesticus2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are two commonly found contaminants associated with various manufacturing products, such as firefighting foam, non-stick coatings, electronics and water repellants. These compounds are persistent, bioaccumulative, and toxic and may therefore pose a serious health risk to living organisms. Earlier studies have shown that PFOS and PFOA affected the fatty acid β-oxidation, i.e. the energy metabolism in liver. This study evaluates the effects of PFOS and PFOA on fatty acid metabolism in domestic chicken liver cells.  Liver tissues were obtained from chicken embryos treated in ovo with PFOS or with PFOA at low (0.1 µg/g) and high (1.0 and 1.6 µg/g) concentration levels. The fatty acids were extracted and derivatized into fatty acid methyl esters (FAMEs). The analysis was conducted by gas chromatography coupled with mass spectrometry. Results showed that a lower concentration of PFOS and a lower percentage of DMSO significantly affected the concentrations of fatty acids in livers of chicken embryos. PFOA-treated samples also showed some significant elevated fatty acid concentrations. Almost all fatty acid concentrations of treated liver samples exceeded the concentrations of the untreated samples.

  • 1562.
    Wikström, Alexander
    et al.
    Örebro University, School of Science and Technology.
    Lundin, Andreas
    Örebro University, School of Science and Technology.
    FÖRBÄTTRAD VIKNOGGRANHET FÖR KONVERTERINGSMASKIN AV WELLPAPP2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Currently there is a problem when manufacturing boxes out of corrugated boards in one of EMBAs machines. The problem is that not all the boxes get the same dimensions. The reason behind this lies in the part of the machine were the fold is made.  To prevent the box to get an oversized dimension some sort of retrofit kit needs to be constructed. This is only to prevent the dimension from being too big. The construction must be made so that it can be mounted on the machines already sold.

    This rapport will be about multiple concepts for EMBA and a recommendation that they should later develop further. 

  • 1563.
    Wilhelmsson, Maria
    Örebro University, School of Science and Technology.
    Djurvälfärd i slaktkycklingproduktion - hur kan den förbättras i Sverige?2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Konsumtionen och produktionen av slaktkyckling ökar både i Sverige och övriga världen. Majoriteten av produktionssystemen är likvärdiga och dessa består av storskaliga system med snabbväxande raser. Förekomsten av produktionssjukdomar varierar världen över och detsamma gäller för medicinering och antibiotikaanvändning. I Sverige finns fyra olika typer av kycklingproduktioner: konventionell, ekologisk enligt EU:s förordning för ekologisk produktion, KRAV-certifierad och konventionell certifierad enligt Svensk Sigills. Sverige anses som ett land som en av de bästa gällande djurskyddslagar- och regler. Dock förekommer brister även i Sverige och den svenska kycklingproduktionen kan behöva förändringar för att öka djurvälfärden. Syftet med denna studie var därför att ta reda på hur djurvälfärden kan förbättras i svensk kycklingproduktion och se över vilka förändringar som behövs. Metoderna som användes i studien var kvalitativa intervjuer och litteratursökningar. Fem personer intervjuades och dessa var forskare och veterinärer på Svensk Fågel, Svensk Sigill och vid olika institutioner på SLU. Litteratursökningen genomfördes under två veckor och gav 12 stycken artiklar. Resultatet från intervjuerna visade att intervjupersonerna hade likvärdiga resonemang för djurvälfärd i många av intervjufrågorna. Några av de viktigaste problemområden som rör djurvälfärd är snabbväxande kycklinghybrider, förekomst av ben- och fotskador, dödlighet i kycklingflockar, transport till slakt och användning av antiparasitära medel. Vad som även kom upp under intervjuerna var konsumenters syn på djurvälfärd. Man menade att konsumenter förespråkar och föredrar en god djurvälfärd, dock att de inte är beredda att betala priset för en bättre djurvälfärd. Slutsatserna som kan dras är att ett flertal områden inom djurvälfärd i kycklingproduktion behöver förbättras och den främsta är att fler långsamväxande hybrider bör börja produceras i Sverige.

  • 1564.
    Wimsatt, Jeffrey
    et al.
    Department of Medicine, School of Medicine, West Virginia University, Morgantown, USA; Department of Epidemiology, School of Public Health, West Virginia University, Morgantown, USA; West Virginia University, Medical Center Drive, Morgantown, USA.
    Villers, Meghan
    Department of Medicine, School of Medicine, West Virginia University, Morgantown, USA.
    Thomas, Laurel
    Department of Medicine, School of Medicine, West Virginia University, Morgantown, USA.
    Kamarec, Stacey
    Department of Medicine, School of Medicine, West Virginia University, Morgantown, USA.
    Montgomery, Caitlin
    Department of Medicine, School of Medicine, West Virginia University, Morgantown, USA.
    Yeung, Leo W. Y.
    Örebro University, School of Science and Technology.
    Hu, Yanqing
    Department of Statistics, West Virginia University, Morgantown, USA.
    Innes, Kim
    Department of Epidemiology, School of Public Health, West Virginia University, Morgantown, USA.
    Oral perfluorooctane sulfonate (PFOS) lessens tumor development in the APC(min) mouse model of spontaneous familial adenomatous polyposis2016In: BMC Cancer, ISSN 1471-2407, E-ISSN 1471-2407, Vol. 16, no 1, 942Article in journal (Refereed)
    Abstract [en]

    Background: Colorectal cancer is the second most common cause of cancer deaths for both men and women, and the third most common cause of cancer in the U.S. Toxicity of current chemotherapeutic agents for colorectal cancer, and emergence of drug resistance underscore the need to develop new, potentially less toxic alternatives. Our recent cross-sectional study in a large Appalachian population, showed a strong, inverse, dose-response association of serum perfluorooctane sulfonate (PFOS) levels to prevalent colorectal cancer, suggesting PFOS may have therapeutic potential in the prevention and/or treatment of colorectal cancer. In these preliminary studies using a mouse model of familial colorectal cancer, the APC(min) mouse, and exposures comparable to those reported in human populations, we assess the efficacy of PFOS for reducing tumor burden, and evaluate potential dose-response effects.

    Methods: At 5-6 weeks of age, APC(min) mice were randomized to receive 0, 20, 250 mg PFOS/kg (females) or 0, 10, 50 and 200 mg PFOS/kg (males) via their drinking water. At 15 weeks of age, gastrointestinal tumors were counted and scored and blood PFOS levels measured.

    Results: PFOS exposure was associated with a significant, dose-response reduction in total tumor number in both male and female mice. This inverse dose-response effect of PFOS exposure was particularly pronounced for larger tumors (r(2) for linear trend = 0.44 for males, p's <0.001).

    Conclusions: The current study in a mouse model of familial adenomatous polyposis offers the first experimental evidence that chronic exposure to PFOS in drinking water can reduce formation of gastrointestinal tumors, and that these reductions are both significant and dose-dependent. If confirmed in further studies, these promising findings could lead to new therapeutic strategies for familial colorectal cancer, and suggest that PFOS testing in both preventive and therapeutic models for human colorectal cancer is warranted.

  • 1565.
    Woldegebriel, Teklu
    Örebro University, School of Science and Technology.
    Role of Autophagy Gene Atg13 in Cancer Cell Proliferation and DNA Damage Response2013Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Autophagy is a process of cellular self-digestive pathway that degrades organelles and accumulated protein aggregates. Due to the promiscuous role of autophagy in the viability and death of tumor cells, its effect on lung cancer cells remained to be clarified. Atg13 is essential for autophagy induction and cells deficient of this protein are characterized by a firmly compromised autophagic activity. In the present study, our main objective was to elucidate the mechanism by which autophagy regulates cell proliferation through Atg13. Using NSCLC, U1810 and A549 cell lines as models, we found that silencing of Atg13 significantly inhibited the proliferation of cells. Furthermore, changes in the distribution of cell cycle and the expression levels of cell cycle related proteins were assessed. In this regard, we showed that the cell cycle distribution was not affected in cells transduced with shRNA targeting Atg13; however, reduction of Atg13 was associated with repression of cyclin A levels. Eventually, in response to DNA damage induced by therapeutic drugs, cells were arrested in the G2 phase indicating the increased sensitivity of Atg13 deficient cells to such drugs. In conclusion our data propose a mechanism that connect Atg13 and cell proliferation in lung cancer cells.

     

  • 1566.
    Wu, Min
    et al.
    Göteborgs universitet.
    Eriksson, Leif A
    Göteborgs universitet.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Theoretical prediction of the protein-protein interaction between Arabidopsis thaliana COP1 and UVR82013In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 132, no 7, UNSP 1371Article in journal (Refereed)
    Abstract [en]

    In plants, ultraviolet-B radiation (280-315 nm) regulates gene expression and plant morphology through the UV RESPONSE LOCUS 8 (UVR8) photoreceptor. The first signaling event after quantal absorbance is the interaction of the UVR8 C-terminus with the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). The nature of the interaction between these two proteins is hitherto unknown. A protein homology model of the Arabidopsis thaliana COP1 seven bladed propeller WD40 repeat domain and de novo folds of the C-terminal 27 amino acid (amino acids 397-423) peptide of Arabidopsis UVR8 (UVR8397-423) is herein reported. Using a theoretical computational docking protocol, the interaction between COP1 and UVR8 was predicted. A core motif was identified in UVR8397-423 comprising adjacent hydrophobic residues V410 and P411 together with a charged residue D412, homologous to corresponding motifs in other COP1-binding proteins, such as ELONGATED HYPOCOTYL 5 (HY5), cryptochrome 1 (CRY1), and salt tolerance proteins STO/STH. The protein-protein interaction between the COP1 WD40 repeat domain and UVR8397-423 reveal binding within a region of COP1 overlapping the binding site for HY5 and the other COP1-interacting proteins. This study provides a framework for understanding docking between UVR8 and COP1, which in turn gives clues for experimental testing of UVR8/COP1 interaction.

  • 1567.
    Wu, Min
    et al.
    Götebrogs universitet.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Eriksson, Leif
    Göteborgs universitet.
    Prediction of the thre-dimensional structure of the plant UVR8 photoreceptor dimer, and the key residues in UV-B regulated signalling pathway2012In: Science and Technology Day 2012.: Poster exhibition, 2012, C28-C28 p.Conference paper (Other academic)
    Abstract [en]

    See attachment

  • 1568.
    Wu, Min
    et al.
    Göteborgs universitet.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Eriksson, Leif
    Göteborgs universitet.
    Umbrella sampling calculations of the bindning free energy in the UVR8 dimer.: key residues in uv-b regulated signalling pathway revealed using dft and md simulation methods2012In: Challenges in biomolecular modeling: from qm to coarse-graining. International Society of Quantum Biology and Pharmacology / [ed] Lennart Nilsson, Stockholm, 2012Conference paper (Refereed)
    Abstract [en]

    The dimeric UVR8 protein is a ultraviolet-B radiation (280-315 nm) photoreceptor that is responsible for the first step in UV-B regulation of gene expression in plants1. Its action comprises the actual absorption of the UV quanta by a Trp array in the protein, followed by monomerisation, and subsequent aggregation with downstream signaling components2. Quantum theoretical DFT calculationsa of excitation spectra of both a large cluster model involving seven tryptophans at the interface of the UVR8 proteins where they are intermixed with positive residues (mainly arginines) and a couple of tyrosines, and smaller fragments thereof, reveal that absorption maxima appearing in the 280-300 nm range for the full cluster result from interactions between the central tryptophans and surrounding arginines2. This observation provides an explanation for the experimentally measured action spectrum of the UVR8-dependent UV-B stimulation of HY5 transcription in mature A. thaliana leaf tissue3. Umbrella sampling methodb was used to calculate the binding free energy for the wild type UVR8 dimer and three of its mutants (R286A, R338A and R286A/R338A), in order to verify the key mutants able to disrupt the dimeric structure.

    See also attached document.

  • 1569.
    Wu, Min
    et al.
    University of Gothenburg, Sweden.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Eriksson, Leif A.
    University of Gothenburg, Sweden.
    Development of non-standard arginine residue parameters for use with the AMBER force fields2013In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 584, 188-194 p.Article in journal (Refereed)
    Abstract [en]

    Amino acid radicals are often involved as intermediates in biological processes, but are difficult to capture by experiment. Computational modeling can be employed to study the features of the species involved. The neutral arginyl radical has previously been detected experimentally using ECD and ETD spectroscopy. Protonation of the radical can occur on the guanidinium carbon, depending on the peptide structure and protein environment. Accurate force fields are essential for reproducing the conformational and dynamic behavior of these intermediates. New AMBER ff99 parameters for the arginyl radical and hydrogenated arginyl side chains are presented based on ab initio quantum chemical calculations. (c) 2013 Elsevier B.V. All rights reserved.

  • 1570.
    Wu, Min
    et al.
    Göteborgs universitet.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Eriksson, Leif A
    Göteborgs universitet.
    Interactions and Stabilities of the UV RESISTANCE LOCUS8 (UVR8) protein dimer and its key mutants2013In: Journal of Chemical Information and Modeling, ISSN 1549-9596, E-ISSN 1549-960X, Vol. 53, no 7, 1736-1746 p.Article in journal (Refereed)
    Abstract [en]

    The dimeric UVR8 protein is a ultraviolet-B radiation (280-315 nm) photoreceptor responsible for the first step in UV-B regulation of gene expression in plants. Its action comprises the actual absorption of the UV quanta by a tryptophan array at the protein-protein interface, followed by monomerisation, and subsequent aggregation with downstream signaling components. A crystal structure of the Arabidopsis thaliana tryptophan-rich wild type UVR8 protein dimer was recently published, showing the presence of several salt bridges involving arginines R146, R286, R338 and R354. In this work, molecular dynamics simulations in conjunction with umbrella sampling was used to calculate the binding free energy for the wild type UVR8 dimer and three of its mutants (R286A, R338A and R286A/R338A), in order to verify whether the key mutants are able to disrupt the dimeric structure as indicated experimentally.

  • 1571.
    Wu, Min
    et al.
    Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Eriksson, Leif A
    Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
    Photochemical reaction mechanism of UV-B-induced monomerization of UVR8 dimers as the first signaling event in UV-B-regulated gene expression in plants2014In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 118, 951-965 p.Article in journal (Refereed)
    Abstract [en]

    The Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) protein has been identified to specifically mediate photomorphogenic UV-B responses by acting as a UV-B photoreceptor. The dimeric structure of the UVR8 protein dissociates into signaling–active monomers upon UV-B exposure, and the monomers rapidly interact with downstream signaling components to regulate gene expression. UVR8 monomers revert to dimers in the absence of UV-B radiation, thereby reversing transcription activation. UVR8 amino acid residues W233 and W285 have been identified to play critical roles in the UVR8 dimer for the response to UV-B irradiation. In the present work, the photo-reaction mechanism for UVR8 monomerization is explored using quantum chemical cluster calculations, and evaluated by molecular dynamics simulations using the wild type UVR8 dimer and novel force field parameters developed for intermediate radicals formed in the photochemical process. Three different models are investigated, which show that the preferred mechanism for UVR8 monomerization involves electron transfer from residue W233 to W285 and onwards to R338 initiated by UV-B irradiation, coupled to simultaneous proton transfer from W233 to D129 leading to the formation of protonated D129, a deprotonated W233 radical and a neutral R338 radical.. Due to the formation of the neutral R338 radical, salt bridges involving this residue are disrupted together with the concomitant interruption of several other key salt bridges R286-D96, R286-D107, R338-D44, R354-E43 and R354-E53. The resulting large decrease in protein-protein interaction energy arising from this sequence of events lead to the monomerization of the UVR8 dimer. The mechanism presented is in accord with all experimental data available to date.

  • 1572.
    Wässman, Jens
    et al.
    Örebro University, School of Science and Technology.
    Andersson, Staffan
    Örebro University, School of Science and Technology.
    Analys av ljudutbredning och dämpningsmöjligheter för mynningsknall och överljudsbang vid provskjutning av tung artilleripjäs2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this work is to investigate the problems of noise due to shooting with large caliber guns and find a way to attenuate the sound. The problem consists of three parts, the muzzle blast, the sonic boom and the burst. The burst won’t be considered in this investigation. Measurements have been made to understand the problem and analyze the different blast waves. Theoretical ideas of damping have been presented. A scaled test of a noise barrier has been made.

    The propagation of sound outdoors is very complex. The affecting elements are investigated.

    The sonic boom is a significant factor in the noise around Bofors. A theoretical model was made to find the beginning of the sonic boom in purpose to tell where a possible damping of the muzzle blast will have an effect. Measurements were made around the cannon to verify the theory. The result was a failure because the measurements had no visible difference.

    Measurements were made around Bofors Test Center to find the length of the propagation in sonic booms. The strength of the shockwave is dependent on the distance. The sonic boom is almost impossible to attenuate.

  • 1573.
    Wöhrnschimmel, Henry
    et al.
    Institute for Chemical and Bioengineering, ETH Zurich, Zürich, Switzerland.
    Scheringer, Martin
    Institute for Chemical and Bioengineering, ETH Zurich, Zürich, Switzerland; Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Brno, Czech Republic.
    Bogdal, Christian
    Institute for Chemical and Bioengineering, ETH Zurich, Zürich, Switzerland; nstitute for Sustainability Sciences ISS, Agroscope, Zürich, Switzerland.
    Hung, Hayley
    Air Quality Processes Research Section, Environment and Climate Change Canada, Toronto, Ontario, Canada.
    Salamova, Amina
    School of Public and Environmental Affairs, Indiana University, Bloomington, USA.
    Venier, Marta
    School of Public and Environmental Affairs, Indiana University, Bloomington, USA.
    Katsoyiannis, Athanasios
    Norwegian Institute for Air Research (NILU) at FRAM e High North Research Centre on Climate and the Environment, Tromsø, Norway.
    Hites, Ronald A.
    School of Public and Environmental Affairs, Indiana University, Bloomington, USA.
    Hungerbuhler, Konrad
    Institute for Chemical and Bioengineering, ETH Zurich, Zürich, Switzerland.
    Fiedler, Heidelore
    Örebro University, School of Science and Technology. DTIE/Chemicals Branch, United Nations Environment Programme, Chatelaine, Switzerland.
    Ten years after entry into force of the Stockholm Convention: What do air monitoring data tell about its effectiveness?2016In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 217, 149-158 p.Article in journal (Refereed)
    Abstract [en]

    More than a decade ago, the Stockholm Convention on Persistent Organic Pollutants (POPs), one of the multilateral environmental agreements administered by the United Nations Environment Programme (UNEP), entered into force. The objective of this Convention is to protect human health and the environment by controlling the releases of POPs. According to its Article 16, the effectiveness of the Stockholm Convention shall be evaluated using comparable monitoring data on the presence of POPs as well as their regional and global environmental transport. Here, we present a time series analysis on atmospheric POP concentrations from 15 monitoring stations in North America and Europe that provide long-term data and have started operations between 1990 and 2003. We systematically searched for temporal trends and significant structural changes in temporal trends that might result from the provisions of the Stockholm Convention. We find that such structural changes do occur, but they are related mostly to effects of national regulations enforced prior to the implementation of the Stockholm Convention, rather than to the enforcement of the provisions laid out in the Convention. One example is that concentrations of polychlorinated biphenyls, many of which started to decrease rapidly during the 1990s. Also effects of chemical transport and fate, for instance the re-volatilization of POPs from secondary sources, are thought to be a cause of some of the observed structural changes. We conclude that a decade of air monitoring data has not been sufficient for detecting general and statistically significant effects of the Stockholm Convention. Based on these lessons, we present recommendations for the future operation of existing monitoring programs and advocate for a stricter enforcement of the provisions of the Stockholm Convention, in the current absence of proof for its effectiveness.

  • 1574.
    Xhafa, Azdren
    et al.
    Örebro University, School of Science and Technology.
    Kalifa, Rezgar
    Örebro University, School of Science and Technology.
    Produktutveckling av gripdon2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The thesis presents the product of grippers for the client Meritor HVS AB. To get a good understanding of how a gripper works, the authors described how robots handling grippers. The contractor has been given the mandate to develop a gripper when the existing gripper has some shortcomings. It is daily facing new improvements, technology develops fast and the aim is therefore both business and designer for continuous improvement. A situation analysis conducted in the initial phase of our work was made to get an overall understanding of the process to be able to continue working to develop a gripper that can handle all varieties of raw material as the company works with. When an internal benchmarking was done in the company placed a strong emphasis on developing a new gripper that could handle all variants of the crown wheel substance that the company must manage. The benefits will then reducing setup time at the station and that of new raw material will then gripper to handle too with without problems. In order to produce a sustainable concept that generated the authors first ideas using a mind map to get a broad knowledge of the problem and to focus on getting the best possible concept to work with. To prove that the developed concepts can handle all varieties of raw material, the authors performed calculations showing that the theoretical concept proposals is sustainable. The concepts presented in the project has been done by the CAD program Creo Parametric. The results of the thesis show that the concept of two parallel hydraulic cylinders meets the requirements we had, and it has also shown a developed product realization that can be implemented in the company.

  • 1575.
    Yanzu, Maxwell
    Örebro University, School of Science and Technology.
    Optimization of DNA preparation and bacterial species identification in blood culture bottles signaling microbial growth2012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 1576.
    Yao, Zhigang
    et al.
    Department of Statistics and Applied Probability, National University of Singapore, Singapore .
    Zhang, Ye
    Örebro University, School of Science and Technology.
    Bai, Zhidong
    KLASMOE and School of Mathematics and Statistics, Northeast Normal University, Changchun, China.
    Eddy, William F.
    Department of Statistics, Carnegie Mellon University, Pittsburgh Pennsylvania, USA.
    Estimating the Number of Sources in Magnetoencephalography Using Spiked Population Eigenvalues2017In: Journal of the American Statistical Association, ISSN 0162-1459, E-ISSN 1537-274XArticle in journal (Refereed)
    Abstract [en]

    Magnetoencephalography (MEG) is an advanced imaging technique used to measure the magnetic fields outside the human head produced by the electrical activity inside the brain. Various source localization methods in MEG require the knowledge of the underlying active sources, which are identified by a priori. Common methods used to estimate the number of sources include principal component analysis or information criterion methods, both of which make use of the eigenvalue distribution of the data, thus avoiding solving the time-consuming inverse problem. Unfortunately, all these methods are very sensitive to the signal-to-noise ratio (SNR), as examining the sample extreme eigenvalues does not necessarily reflect the perturbation of the population ones. To uncover the unknown sources from the very noisy MEG data, we introduce a framework, referred to as the intrinsic dimensionality (ID) of the optimal transformation for the SNR rescaling functional. It is defined as the number of the spiked population eigenvalues of the associated transformed data matrix. It is shown that the ID yields a more reasonable estimate for the number of sources than its sample counterparts, especially when the SNR is small. By means of examples, we illustrate that the new method is able to capture the number of signal sources in MEG that can escape PCA or other information criterion based methods.

  • 1577.
    Ydstål, Danielle
    Örebro University, School of Science and Technology.
    Health Risks of VOCs and Aldehydes in Indoor Air: A Case Study of Three Beauty Salons and a Gym2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    People tend to spend more and more time indoors, constantly breathing indoor air. In indoor air there is a mixture of chemicals from both the outdoor air, which is let in through the ventilation systems, and from the materials and products that are used indoors. To maintain good health, good indoor air quality (IAQ) is essential, not only at home but also at work. Some workplaces are more prone to air contamination than others, beauty salons being a great example. This is simply because a large number of products are used, all with a complex composition of different substances.

    In this study, the concentrations of volatile organic compounds (VOCs) and aldehydes are measured in the air of different types of beauty salons and a gym. Three different types of beauty salons are included; one hair salon using traditional hair products, one hair salon using organic products and the third salon is a nail salon. The gym is included as a reference facility where low emissions of VOCs and aldehydes are expected. Also, a sample of the outdoor air in central Örebro is taken to be able to conclude that the indoor pollution is indeed from indoor sources, using indoor/outdoor ratio (I/O ratio).

    To evaluate the risk associated with the measured concentrations of VOCs and aldehydes a new approach using chronic limit values for calculation of hazard index (HI) and maximum cumulative ratio (MCR) is used as well as the Swedish occupational exposure limits. HI is calculated by adding all substances in the mixture’s hazard quotients (HQs), which is the measured concentration divided by the limit value. The HI is an indication of the strength of the toxicity of the mixture where a value above 1 is of concern, whereas MCR is used to identify if one or several substances are responsible for the total toxicity by dividing the HI by the maximum HQ in the mixture. The results showed a low risk for all sampling sites, except personal sampling in salon 3, where HI > 1 and MCR>2, which means concern for combined effect by several substances.

  • 1578.
    Yeung, Leo W. Y.
    et al.
    Örebro University, School of Science and Technology. Department of Chemistry, University of Toronto, Toronto ON, Canada.
    Dassuncao, Clifton
    Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge MA, United States.
    Mabury, Scott
    Department of Chemistry, University of Toronto, Toronto, ON, Canada.
    Sunderland, Elsie M
    Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge MA, United States.
    Zhang, Xianming
    Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge MA, United States.
    Lohmann, Rainer
    Graduate School of Oceanography, University of Rhode Island, Narragansett RI, United States.
    Vertical Profiles, Sources, and Transport of PFASs in the Arctic Ocean2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 12, 6735-6744 p.Article in journal (Refereed)
    Abstract [en]

    The relative importance of atmospheric versus oceanic transport for poly- and perfluorinated alkyl substances (PFASs) reaching the Arctic Ocean is not well understood. Vertical profiles from the Central Arctic Ocean and shelf water, snow and meltwater samples were collected in 2012; 13 PFASs (C6-C12 PFCAs; C6, 8, 10 PFSAs; MeFOSAA and EtFOSAA; and FOSA) were routinely detected (range: <5-343 pg/L). PFASs were only detectable above 150 m depth in the polar mixed layer (PML) and halocline. Enhanced concentrations were observed in snow and meltpond samples, implying atmospheric deposition as an important source of PFASs. Model results suggested atmospheric inputs to account for 34-59% (∼11-19 pg/L) of measured PFOA concentrations in the PML (mean 32 ± 15 pg/L). Modeled surface and halocline measurements for PFOS based on North Atlantic inflow (11-36 pg/L) agreed with measurements (mean, 17, range <5-41 pg/L). Modeled deep water concentrations below 200 m (5-15 pg/L) were slightly higher than measurements (<5 pg/L), suggesting the lower bound of PFAS emissions estimates from wastewater and rivers may provide the best estimate of inputs to the Arctic. Despite low concentrations in deep water, this reservoir is expected to contain most of the PFOS mass in the Arctic (63-180 Mg) and is projected to continue increasing to 2038.

  • 1579.
    Yeung, Leo W. Y.
    et al.
    Örebro University, School of Science and Technology. Department of Chemistry, University of Toronto, Toronto Ontario, Canada.
    Stadey, Christopher
    Waters Corporation, Mississauga ON, Canada.
    Mabury, Scott A
    Department of Chemistry, University of Toronto, Toronto Ontario, Canada.
    Simultaneous analysis of perfluoroalkyl and polyfluoroalkyl substances including ultrashort-chain C2 and C3 compounds in rain and river water samples by ultra performance convergence chromatography2017In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1522, 78-85 p.Article in journal (Refereed)
    Abstract [en]

    An analytical method using ultra performance convergence chromatography (UPC(2)) coupled to a tandem mass spectrometer operated in negative electrospray mode was developed to measure perfluoroalkyl and polyfluoroalkyl substances (PFASs) including the ultrashort-chain PFASs (C2-C3). Compared to the existing liquid chromatography tandem mass spectrometry method using an ion exchange column, the new method has a lower detection limit (0.4pg trifluoroacetate (TFA) on-column), narrower peak width (3-6s), and a shorter run time (8min). Using the same method, different classes of PFASs (e.g., perfluoroalkyl sulfonates (PFSAs) and perfluorinated carboxylates (PFCAs), perfluorinated phosphonates (PFPAs) and phosphinates (PFPiAs), polyfluoroalkyl phosphate diesters (diPAPs)) can be measured in a single analysis. Rain (n=2) and river water (n=2) samples collected in Toronto, ON, were used for method validation and application. Results showed that short-chain PFAS (C2-C7 PFCAs and C4 PFSA) contributed to over 80% of the detectable PFASs in rain samples and the C2-C3 PFASs alone accounted for over 40% of the total. Reports on environmental levels of these ultrashort-chain PFASs are relatively scarce. Relatively large contribution of these ultrashort-chain PFASs to the total PFASs indicate the need to include the measurement of short-chain PFASs, especially C2 and C3 PFASs, in environmental monitoring. The sources of TFA and other short-chain PFASs in the environment are not entirely clear. The newly developed analytical method may help further investigation on the sources and the environmental levels of these ultrashort-chain PFASs.

  • 1580.
    Yeung, Leo W. Y.
    et al.
    Örebro University, School of Science and Technology. Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.
    Stadey, Christopher
    Waters Corporation, Northam, Mississauga ON, Canada.
    Mabury, Scott A.
    Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.
    Simultaneous analysis of perfluoroalkyl and polyfluoroalkyl substances including ultrashort-chain C2 and C3 compounds in rain and river water samples by ultra performance convergence chromatography2017In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1522, 78-85 p.Article in journal (Refereed)
    Abstract [en]

    An analytical method using ultra performance convergence chromatography (UPC(2)) coupled to a tandem mass spectrometer operated in negative electrospray mode was developed to measure perfluoroalkyl and polyfluoroalkyl substances (PFASs) including the ultrashort-chain PFASs (C2-C3). Compared to the existing liquid chromatography tandem mass spectrometry method using an ion exchange column, the new method has a lower detection limit (0.4pg trifluoroacetate (TFA) on-column), narrower peak width (3-6s), and a shorter run time (8min). Using the same method, different classes of PFASs (e.g., perfluoroalkyl sulfonates (PFSAs) and perfluorinated carboxylates (PFCAs), perfluorinated phosphonates (PFPAs) and phosphinates (PFPiAs), polyfluoroalkyl phosphate diesters (diPAPs)) can be measured in a single analysis. Rain (n=2) and river water (n=2) samples collected in Toronto, ON, were used for method validation and application. Results showed that short-chain PFAS (C2-C7 PFCAs and C4 PFSA) contributed to over 80% of the detectable PFASs in rain samples and the C2-C3 PFASs alone accounted for over 40% of the total. Reports on environmental levels of these ultrashort-chain PFASs are relatively scarce. Relatively large contribution of these ultrashort-chain PFASs to the total PFASs indicate the need to include the measurement of short-chain PFASs, especially C2 and C3 PFASs, in environmental monitoring. The sources of TFA and other short-chain PFASs in the environment are not entirely clear. The newly developed analytical method may help further investigation on the sources and the environmental levels of these ultrashort-chain PFASs.

  • 1581.
    Yeung, Leo W.Y.
    et al.
    Örebro University, School of Science and Technology. Örebro University.
    Eriksson, Ulrika
    Örebro University, School of Science and Technology.
    Tidstrend av oidentifierade poly- och perfluorerade alkylämnen i slam från reningsverk i Sverige2017Report (Other academic)
    Abstract [en]

    The aims of this investigation are 1) to study spatial variation in PFAS discharge by measuring PFAS in sludge samples collected from four wastewater treatment plants (WWTPs: Öhn - Umeå, Bergkvara - Torsås, Henriksdal – Stockholm, and Gässlösa - Borås); 2) to evaluate the amount of unidentified PFAS, if any, in the sludge samples by measuring total organofluorine (TOF) in the samples; 3) to study the temporal discharge and pattern of PFASs by measuring different PFASs in archived sludge samples from two WWTPs (Henriksdal and Gässlösa); and 4) to evaluate temporal changes of the amount of unidentified PFAS, if any, by measuring the amount of TOF in the archived samples from these two WWTPs. Levels of TOF and PFAS are reported for sludge samples from the four WWTPs collected in 2015; temporal analyses of TOF and PFASs were conducted on sludge samples from two WWTPs collected between 2004 and 2015.

    Different classes of PFASs including PFCAs, PFSAs, FTSAs, FTCAs, diPAPs, FOSAs/FOSEs, diSAmPAP, FOSAAs, PFPAs and PFPiAs were detected in the sludge samples. The levels of TOF and unidentified PFAS were shown to more related to types of industries connected to the WWTPs, not necessarily related to number of people served in that area and the scale of WWTP. Quantifiable PFAS only accounted for 5 to 11% of the TOF in samples collected in 2015 indicating that 89-95% of the measured organofluorine in the samples was unidentified. TOF levels from Gässlösa were approximately 1.6 – 17.7 times higher than those of Henriksdal in corresponding year. The proportion of quantifiable PFAS to TOF decreased from 21% in 2004 to 11% in 2015 in samples from Henriksdal; at the same time increasing levels of unidentified PFAS was also observed between 2012 and 2015

    Syftet med denna studie var 1) att studera geografiska variationer i utsläpp av PFASs genom att mäta PFAS i slamprover från fyra olika reningsverk (Öhn - Umeå, Bergkvara - Torsås, Henriksdal – Stockholm och Gässlösa - Borås); 2) att utvärdera om slammet innehåller oidientifierade PFASs och i sådana fall kvantifiera mängden av dessa; 3) att studera hur profilen av PFAS-ämnen förändras över tid genom att mäta olika PFAS-ämnen i arkiverade slamprover från två reningsverk (Henriksdal och Gässlösa); och 4) att bestämma andelen oidentifierade PFAS genom att mäta totalhalten organiskt fluor (TOF) i de arkiverade proverna från Henriksdal och Gässlösa.

    I denna studie rapporteras halterna av TOF och PFAS i slamprover från de fyra ovan nämnda reningsverken insamlade under 2015; vidare rapporteras en tidstrendsstudie utförd för TOF och PFAS i slamprover från Henriksdal mellan 2004 och 2015. Ett flertal PFAS-klasser detekterades i proverna; PFCAs, PFSAs, FTSAs, FTCAs, diPAPs, FOSAs/FOSEs, diSAmPAP, FOSAAs, PFPAs och PFPiAs. Halterna av oidentifierade PFASs visade sig vara relaterade främst till typ av industriell verksamhet i anslutning till reningsverket, snarare än antalet personer anslutna till och storlek på reningsverken. Identifierade PFAS-halter utgjorde endast 5 - 11% av TOF i proverna insamlade under 2015, vilket indikerade att 89 - 95% av TOF var oidentifierade ämnen. Halten TOF i slamproverna från Gässlösa var uppskattningsvis 1.6 – 17.7 gånger högre än TOF i slamprover från Henriksdal motsvarande år. Andelen identifierade PFAS-halter i förhållande till TOF minskade från 21% under 2004 till 11% under 2015 i slamprover från Henriksdal, ökade halter av oidentiferade PFASs observerades också mellan 2012 och 2015.

  • 1582.
    Yeung, Leo W.Y.
    et al.
    Örebro University, School of Science and Technology. Örebro University.
    Eriksson, Ulrika
    Örebro University, School of Science and Technology.
    Kärrman, Anna
    Örebro University, School of Science and Technology.
    Pilotstudie avseende oidentifierade poly- och perfluorerade alkylämnen i slam och avloppsvatten från reningsverk i Sverige2016Report (Other academic)
    Abstract [sv]

    Abstract [sv]

    Syftet med denna studie var att studera totalhalten av PFASs samt andelen okända, hittills ännu ej identifierade PFAS-ämnen i vatten och slam från svenska reningsverk genom att analysera totalt organiskt fluor (TOF) och kvantifierbara PFAS-ämnen. Studien syftar till att kartlägga omfattningen av kända och okända PFAS-ämnen, både dem som är i omlopp och används i produkter i samhället, och dem som släpps ut i miljön. Avloppsvatten (ingående och utgående) och slam provtogs under 2015 och 2016 vid tre olika reningsverk; Gässlösa (Borås), Henriksdal (Stockholm) och Öhn (Umeå). I denna rapport redovisas halter av TOF och PFAS-ämnen i slam från 2016 och ingående och utgående avloppsvatten från 2015 och 2016. Flera olika PFAS-klasser detekterades i slam och avloppsvatten; PFCAs, PFSAs, FTSAs, FTCAs, FTUCAs, FOSAs, FOSAAs, diPAPs, PFPAs och PFPiAs. De neutrala och/eller katjoniska PFAS-ämnena i ingående och utgående vatten var ej identiferbara, medan 79-95% av de anjoniska PFAS-ämnen var okända, ej identiferbara ämnen. I slamproverna ´var en betydande del (42-82%) okända ämnen.

    Abstract [en]

    The aim of the this investigation are 1) to measure the amount and proportion of unidentified PFASs had been used in daily life by analyzing total organofluorine (TOF) and quantifiable PFASs in influent samples; and 2) to measure the amount and proportion of unidentified PFASs released into the environment by analyzing TOF and quantifiable PFASs in effluent samples and sludge samples from municipal waste water treatment plants. Sewage (influent and effluent) and sludge were collected in 2015 and 2016 from three wastewater treatment plants (Gässlösa (Borås), Henriksdal (Stockholm) and Öhn (Umeå)). Levels of TOF and PFAS in sludge from 2016 and filtered effluent and influent samples from 2015 and 2016 are reported. Different classes of PFASs including PFCAs, PFSAs, FTSAs, FTCAs, diPAPs, FTUCAs, FOSAs, FOSAAs, PFPAs and PFPiAs were detected in sewage and sludge samples. For influent and effluent samples, all detectable neutral and/or cationic PFASs remained unidentified; for the anionic fraction, 79-94% of the TOF were unidentified. For sludge samples, a significant proportion (42-82%) of total anionic organofluorine remained unidentified

  • 1583.
    Yngström, Malin
    Örebro University, School of Science and Technology.
    Elevers uppfattningar om digital teknik i matematikundervisningen2016Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study is interested in students´ experience of digital technology in mathematics education. A quantitative survey of 239 students is the basis for the results. The results show a primary positive view on the use of computers or tablets in mathematics education, but also that there are potentials that can be developed. The use of digital technology was limited to almost exclusively skills training and not to any great extent of variants. There is a great potential in the use of digital technology in several ways in the teaching, e.g. visualization. Students also responded that the programs were easy, and that it was good, as later discussed. How variations in teaching with digital technology appears and that some of the students answered that they lack a common thread in teaching, are brought up in the discussion.

  • 1584.
    Yngström, Malin
    Örebro University, School of Science and Technology.
    Lärarens och elevernas kommunikation i matematikundervisningen: En litteraturstudie om den verbala kommunikationen i klassrummet2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this review is to examine what the research field says about the communication between teachers and pupils. Can any conclusions be made about the communications that exists? In what way and how much has the research concerned about different aspects of communication between teachers and pupils and which aspects conduce development of the pupils´ knowledge? Web of Science were used for a database search and by manual reviewing, 48 articles present my research field. Seven of the articles represent the dispersion of the research field. Result: A small majority of the articles emphasize the teachers´ communication with the pupils and that it has importance for the development of the pupils´ knowledge. These articles belong to the group that has curriculum and a learning theory, were communication between individuals are considered developing, as its foundation. The other articles consider the teachers’ communication to the pupils as important for the knowledge development.

  • 1585.
    Yousaf, Bilal
    Örebro University, School of Science and Technology.
    Quantitative and Site-specific DNA Methylation Analysis of MTHFR and MTR Genes Involved in the One-carbon Metabolism2012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 1586.
    Yu, Miao
    et al.
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
    Liu, Jiyan
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
    Wang, Thanh
    Örebro University, School of Science and Technology.
    Zhang, Aiqian
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
    Wang, Yawei
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
    Zhou, Qunfang
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
    Jiang, Guibin
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
    Structure prediction of methyoxy-polybrominated diphenyl ethers (MeO-PBDEs) through GC-MS analysis of their corresponding PBDEs2016In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 152, 9-14 p.Article in journal (Refereed)
    Abstract [en]

    It is hard to quantify the trace pollutants in the environment without the corresponding reference standards. Structure identifications of unknown organic pollutants are thus of great importance in environmental analysis. As for polybrominated diphenyl ethers (PBDE) with one substituent of methoxyl group, there are 837 congeners, but only 32 standards are commercially available. In this work, an effective method based on gas chromatography coupled with mass spectrometry (GC-MS) was proposed to predict the potential structures of methoxylated polybrominated diphenyl ethers (MeO-PBDEs). The mass fragmentation pattern using SIM mode not only provided the useful information on the substitution position of methoxyl group, the number of Br atoms, but also guaranteed the high sensitivity for trace analysis. Br distribution patterns of the unknown MeO-PBDEs were revealed by a linear regression model with dummy variables which described the retention time relationship between MeO-PBDEs and the corresponding PBDEs on different types of GC columns. This method was successfully used to identify three new MeO-PBDEs metabolites of BDE-28 as 4-MeO-BDE-22, 4'-MeO-BDE-25 and 4-MeO-BDE-31 in the pumpkins. Therefore, the newly developed structure prediction model based on GC-MS behavior is helpful in the evaluation of unknown PBDE metabolites in the environment.

  • 1587.
    Zaganidis, Anestis
    et al.
    University of Lincoln.
    Magnusson, Martin
    Örebro University, School of Science and Technology.
    Duckett, Tom
    University of Lincoln.
    Cielniak, Grzegorz
    University of Lincoln.
    Semantic-assisted 3D Normal Distributions Transform for scan registration in environments with limited structure2017In: 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2017, 4064-4069 p.Conference paper (Refereed)
    Abstract [en]

    Point cloud registration is a core problem of many robotic applications, including simultaneous localization and mapping. The Normal Distributions Transform (NDT) is a method that fits a number of Gaussian distributions to the data points, and then uses this transform as an approximation of the real data, registering a relatively small number of distributions as opposed to the full point cloud. This approach contributes to NDT’s registration robustness and speed but leaves room for improvement in environments of limited structure.

    To address this limitation we propose a method for the introduction of semantic information extracted from the point clouds into the registration process. The paper presents a large scale experimental evaluation of the algorithm against NDT on two publicly available benchmark data sets. For the purpose of this test a measure of smoothness is used for the semantic partitioning of the point clouds. The results indicate that the proposed method improves the accuracy, robustness and speed of NDT registration, especially in unstructured environments, making NDT suitable for a wider range of applications.

  • 1588.
    Zekavat, Amir Reza
    et al.
    Örebro University, School of Science and Technology.
    Pejryd, Lars
    Örebro University, School of Science and Technology.
    Surface characterization of additively manufactured Al10SiMg thin-walled structures2016In: 7th Swedish Production Symposium, 2016Conference paper (Refereed)
    Abstract [en]

    Additive manufacturing (AM) is a newly developed technique for fabrication of parts with complexgeometries. Despite the fact that this technique has made it possible to fabricate near net shape and complexgeometries, there can be a mismatch between as-designed and as-fabricated geometries. These geometricalimperfections can hinder the structural response of fabricated structures by not fulfilling the strength theyare designed for. These mismatches, specifically surface morphology become even more important factorin case of manufacturing of thin-walled structures by AM. This is due to the fact that the surface regionwhich is mainly consist of partially melted powders does not necessarily contribute in strength. Thus, theeffect of surface morphology on mechanical properties in such structure should be investigated and takeninto account in the design stage. In this study high resolution X-ray computed tomography (micro-CT) hasbeen used for qualitative investigation of surface morphology of specimens made of AlSi10Mg. Flatspecimens with different thicknesses has been fabricated by selective laser melting (SLM). Using micro-CT it was possible to non-destructively measure the surface region in thin-walled builds. The measurementfrom micro-CT as well as result from optical profilometry showed the usefulness of micro-CT for thoroughinvestigation of AM parts. The study showed that micro-CT is a robust method for qualitative measurementof surface morphology of parts made of AlSi10Mg using SLM technique. It also gave an insight on wherethe geometrical mismatch specifically at micro scale become an important factor in design of such structuresfabricated using SLM technique. The result from this study lead to development in design stage of AMprocesses.

  • 1589.
    Zekavat, Amir Reza
    et al.
    Örebro University, School of Science and Technology.
    Pejryd, Lars
    Örebro University, School of Science and Technology.
    Ekengren, Jens
    Örebro University, School of Science and Technology.
    Tracking the shape deformation of voids from tensile loading by the use of computed tomography2015In: Digital Industrial Radiology and Computed Tomography (DIR 2015), 2015, 18034Conference paper (Refereed)
    Abstract [en]

    The understanding of interaction between voids such as pores or holes in additive manufactured open structures is of importance in understanding the strength of components. Behavior in three dimensions is of particular interest. X-ray tomography is one of the few techniques that has the possibility to nondestructively aid in analyzing issues such as shape deformation. In this work, X-ray computed tomography was applied as a nondestructive tool for tracking the shape deformation of voids.

    A simplified model representing three dimensional voids is used to investigate the effect of influential parameters like void size, their distance from each other and orientation of voids in respect to the uniaxial tensile load. A set of ex-situ X-ray micro tomography tensile test is performed on flat aluminum (6082-T6) tensile bars with drilled through holes representing different configuration of voids. Digital image correlation was used to measure the strain localization in the adjacent area of the holes. Corresponding Finite Element (FE) analysis is performed to predict the shape deformation and by this validate the model. This modelling may give a better insight of pores interaction under more complex loading scenarios and leads to better controllability of internal structure design of additive manufactured (AM) parts.

  • 1590.
    Zengin, Gulis
    et al.
    Chalmers University of Technology, Göteborg, Sweden.
    Johansson, Goran
    Chalmers University of Technology, Göteborg, Sweden.
    Johansson, Peter
    Örebro University, School of Science and Technology. Chalmers University of Technology, Göteborg, Sweden.
    Antosiewicz, Tomasz J.
    Chalmers University of Technology, Göteborg, Sweden; University of Warsaw, Warsaw, Poland.
    Käll, Mikael
    Chalmers University of Technology, Göteborg, Sweden.
    Shegai, Timur
    Chalmers University of Technology, Göteborg, Sweden.
    Approaching the strong coupling limit in single plasmonic nanorods interacting with J-aggregates2013In: Scientific Reports, ISSN 2045-2322, Vol. 3, 3074- p.Article in journal (Refereed)
    Abstract [en]

    We studied scattering and extinction of individual silver nanorods coupled to the J-aggregate form of the cyanine dye TDBC as a function of plasmon - exciton detuning. The measured single particle spectra exhibited a strongly suppressed scattering and extinction rate at wavelengths corresponding to the J-aggregate absorption band, signaling strong interaction between the localized surface plasmon of the metal core and the exciton of the surrounding molecular shell. In the context of strong coupling theory, the observed "transparency dips" correspond to an average vacuum Rabi splitting of the order of 100 meV, which approaches the plasmon dephasing rate and, thereby, the strong coupling limit for the smallest investigated particles. These findings could pave the way towards ultra-strong light-matter interaction on the nanoscale and active plasmonic devices operating at room temperature.

  • 1591.
    Zhang, Haiyan
    et al.
    College of Environment, Zhejiang University of Technology, Hangzhou, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
    Vestergren, Robin
    Norwegian Institute for Air Research (NILU), FRAM − High North Research Centre on Climate and the Environment, Tromsø, Norway; ACES - Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden .
    Wang, Thanh
    Örebro University, School of Science and Technology. State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
    Yu, Junchao
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
    Jiang, Guibin
    State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
    Herzke, Dorte
    Norwegian Institute for Air Research (NILU), FRAM − High North Research Centre on Climate and the Environment, Tromsø, Norway.
    Geographical Differences in Dietary Exposure to Perfluoroalkyl Acids between Manufacturing and Application Regions in China2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 10, 5747-5755 p.Article in journal (Refereed)
    Abstract [en]

    Emissions of perfluoroalkyl acids (PFAAs) have increased in China over the past decade, but human exposure pathways are poorly understood. Here we analyzed 15 PFAAs in commonly consumed food items and calculated body weight normalized dietary intake rates (estimated dietary intake, EDIs) in an area with ongoing PFAA production (Hubei province; n = 121) and an urbanized coastal area (Zhejiang province; n = 106). Geographical differences in concentrations were primarily observed for perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) in animal food items and short chain PFAAs in vegetable food items. The average EDI of Sigma PFAAs for adults in Hubei (998 ng kg(-1) day(-1)) was more than 2 orders of magnitude higher than that in Zhejiang (9.03 ng kg-1 day(-1)). In Hubei province, the average EDI of PFOS for adults (87 ng kg(-1) day(-1)) was close to or exceeded advisory guidelines used in other countries indicating health risks for the population from long-term exposure. Yet, PFOS could only account for about 10% of the EDI of Sigma PFAAs in the Hubei province, which was dominated by short-chain PFAAs through consumption of vegetables. The large contribution of short-chain PFAAs to the total EDIs in manufacturing areas emphasize the need for improved exposure and hazard assessment tools of these substances.

  • 1592.
    Zhang, Liwei
    et al.
    University of Hamburg, Germany.
    Saffiotti, Alessandro
    Örebro University, School of Science and Technology.
    Pecora, Federico
    Örebro University, School of Science and Technology.
    Zhang, Jianwei
    University of Hamburg, Germany.
    Evaluation metrics for an experience-based mobile artificial cognitive system2014In: 11th World Congress on Intelligent Control and Automation (WCICA2014), Springer Berlin/Heidelberg, 2014, 2225-2232 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, an FIM (Fitness to Ideal Model)and a DLen (Description Length) based evaluation approachhas been developed to measure the benefit of learning from experienceto improve the robustness of the robot’s behavior. Theexperience based mobile artificial cognitive system architectureis briefly described and adopted by a PR2 service robot withinthe EU-FP7 funded project RACE. The robot conducts typicaltasks of a waiter. Temporal and lasting obstacles and standardtable items, as shown in the demonstrations of “Deal-withobstacles”and “Clear-table-intelligently”, are being adoptedin this work to test the proposed evaluation metrics, validateit on a real PR2 robot system and present the evaluationresults. The relationship between the FIM and DLen has beenvalidated. This work proposes an effective approach to evaluatea cognitive service robot system which enhances its performanceby learning.

  • 1593.
    Zhang, Ye
    et al.
    Örebro University, School of Science and Technology. Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden; .
    Guang-Liang, Lin
    Department of Mathematics, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
    Forssén, Patrik
    Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden.
    Gulliksson, Mårten
    Örebro University, School of Science and Technology.
    Fornstedt, Torgny
    Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden.
    Cheng, Xiao-Liang
    Department of Mathematics, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
    A regularization method for the reconstruction of adsorption isotherms in liquid chromatography2016In: Inverse Problems, ISSN 0266-5611, E-ISSN 1361-6420, Vol. 32, no 10, 105005Article in journal (Refereed)
    Abstract [en]

    Determining competitive adsorption isotherms is an open problem in liquid chromatography. Since traditional experimental trial-and-error approaches are too complex and expensive, a modern technique of obtaining adsorption isotherms is to solve the inverse problem so that the simulated batch separation coincides with actual experimental results. This is a typical ill-posed problem. Moreover, in almost all cases the observed concentration at the outlet is the total response of all components, which makes the problem more difficult. In this work, we tackle the ill-posedness with a new regularization method, which is based on the fact that the adsorption isotherms do not depend on the injection profile. The proposed method transfers the original problem to an optimization problem with a time-dependent convection–diffusion equation constraint. Iterative algorithms for solving constraint optimization problems for both the equilibrium-dispersive and the transport-dispersive models are developed. The mass transfer resistance is also estimated by the proposed inverse method. A regularization parameter selection method and the convergence property of the proposed algorithm are discussed. Finally, numerical tests for both synthetic problems and real-world problems are given to show the efficiency and feasibility of the proposed regularization method.

  • 1594.
    Zhang, Ye
    et al.
    Örebro University, School of Science and Technology.
    Gulliksson, Mårten
    Örebro University, School of Science and Technology.
    Hernandez Bennetts, Victor
    Örebro University, School of Science and Technology.
    Schaffernicht, Erik
    Örebro University, School of Science and Technology.
    Reconstructing gas distribution maps via an adaptive sparse regularization algorithm2016In: Inverse Problems in Science and Engineering, ISSN 1741-5977, E-ISSN 1741-5985, Vol. 24, no 7, 1186-1204 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, we present an algorithm to be used by an inspectionrobot to produce a gas distribution map and localize gas sources ina large complex environment. The robot, equipped with a remotegas sensor, measures the total absorption of a tuned laser beam andreturns integral gas concentrations. A mathematical formulation ofsuch measurement facility is a sequence of Radon transforms,which isa typical ill-posed problem. To tackle the ill-posedness, we developa new regularization method based on the sparse representationproperty of gas sources and the adaptive finite-element method. Inpractice, only a discrete model can be applied, and the quality ofthe gas distributionmap depends on a detailed 3-D world model thatallows us to accurately localize the robot and estimate the paths of thelaser beam. In this work, using the positivity ofmeasurements and theprocess of concentration, we estimate the lower and upper boundsof measurements and the exact continuous model (mapping fromgas distribution to measurements), and then create a more accuratediscrete model of the continuous tomography problem. Based onadaptive sparse regularization, we introduce a new algorithm thatgives us not only a solution map but also a mesh map. The solutionmap more accurately locates gas sources, and the mesh map providesthe real gas distribution map. Moreover, the error estimation of theproposed model is discussed. Numerical tests for both the syntheticproblem and practical problem are given to show the efficiency andfeasibility of the proposed algorithm.

  • 1595.
    Zhang, Ye
    et al.
    Örebro University, School of Science and Technology. Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden.
    Lin, G.
    Department of Mathematics, Zhejiang University, Hangzhou, China.
    Gulliksson, Mårten
    Örebro University, School of Science and Technology.
    Forssén, P.
    Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden.
    Fornstedt, T.
    Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden.
    Cheng, X.
    Department of Mathematics, Zhejiang University, Hangzhou, China.
    An adjoint method in inverse problems of chromatography2017In: Inverse Problems in Science and Engineering, ISSN 1741-5977, E-ISSN 1741-5985, Vol. 25, no 8, 1112-1137 p.Article in journal (Refereed)
    Abstract [en]

    How to determine adsorption isotherms is an issue of significant importance in chromatography. A modern technique of obtaining adsorption isotherms is to solve an inverse problem so that the simulated batch separation coincides with actual experimental results. In this work, as well as the natural least-square approach, we consider a Kohn–Vogelius type formulation for the reconstruction of adsorption isotherms in chromatography, which converts the original boundary fitting problem into a domain fitting problem. Moreover, using the first momentum regularizing strategy, a new regularization algorithm for both the Equilibrium-Dispersive model and the Transport-Dispersive model is developed. The mass transfer resistance coefficients in the Transport-Dispersive model are also estimated by the proposed inverse method. The computation of the gradients of objective functions for both of the two models is derived by the adjoint method. Finally, numerical simulations for both a synthetic problem and a real-world problem are given to show the robustness of the proposed algorithm.

  • 1596.
    Zhang, Ye
    et al.
    Örebro University, School of Science and Technology.
    Lukyanenko, D. V.
    Physical Faculty, Department of Mathematics, Lomonosov Moscow State University, Moscow, Russia.
    Yagola, A. G.
    Physical Faculty, Department of Mathematics, Lomonosov Moscow State University, Moscow, Russia.
    Using Lagrange principle for solving two-dimensional integral equation with a positive kernel2016In: Inverse Problems in Science and Engineering, ISSN 1741-5977, E-ISSN 1741-5985, Vol. 24, no 5, 811-831 p.Article in journal (Refereed)
    Abstract [en]

    This article is devoted to a Lagrange principle application to an inverse problem of a two-dimensional integral equation of the first kind with a positive kernel. To tackle the ill-posedness of this problem, a new numerical method is developed. The optimal and regularization properties of this method are proved. Moreover, a pseudo-optimal error of the proposed method is considered. The efficiency and applicability of this method are demonstrated in a numerical example of an image deblurring problem with noisy data.

  • 1597.
    Zhang, Ye
    et al.
    Örebro University, School of Science and Technology.
    Lukyanenko, Dmitry V.
    Department of Mathematics, Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation.
    Yagola, Anatoly G.
    Department of Mathematics, Faculty of Physics, M. V. Lomonosov Moscow State University.
    An optimal regularization method for convolution equations on the sourcewise represented set2015In: Journal of Inverse and Ill-Posed Problems, ISSN 0928-0219, E-ISSN 1569-3945, Vol. 23, no 5, 465-475 p.Article in journal (Refereed)
    Abstract [en]

    In this article, we consider an inverse problem for the integral equation of the convolution typein a multidimensional case. This problem is severely ill-posed. To deal with this problem, using a prioriinformation (sourcewise representation) based on optimal recovery theory we propose a new method. Theregularization and optimization properties of this method are proved. An optimal minimal a priori error ofthe problem is found. Moreover, a so-called optimal regularized approximate solution and its correspondingerror estimation are considered. Eciency and applicability of this method are demonstrated in a numericalexample of the image deblurring problem with noisy data.

  • 1598.
    Zhang, Yue
    et al.
    MoE Engineering Research Center for Software/Hardware Co-Design Technology and Application, East China Normal University, Shanghai, China; National Trusted Embedded Software Engineering Technology Research Center (No. 2012FU125X15), Shanghai, China.
    Dragoni, Nicola
    Örebro University, School of Science and Technology. DTU Compute, Technical University of Denmark, Richard Petersens Plads, Kongens Lyngby, Denmark.
    Wang, Jiangtao
    MoE Engineering Research Center for Software/Hardware Co-Design Technology and Application, East China Normal University, Shanghai, China; National Trusted Embedded Software Engineering Technology Research Center (No. 2012FU125X15), Shanghai, China.
    A Framework and Classification for Fault Detection Approaches in Wireless Sensor Networks with an Energy Efficiency Perspective2015In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, 678029Article, review/survey (Refereed)
    Abstract [en]

    Wireless Sensor Networks (WSNs) are more and more considered a key enabling technology for the realisation of the Internet of Things (IoT) vision. With the long term goal of designing fault-tolerant IoT systems, this paper proposes a fault detection framework for WSNs with the perspective of energy efficiency to facilitate the design of fault detection methods and the evaluation of their energy efficiency. Following the same design principle of the fault detection framework, the paper proposes a classification for fault detection approaches. The classification is applied to a number of fault detection approaches for the comparison of several characteristics, namely, energy efficiency, correlation model, evaluation method, and detection accuracy. The design guidelines given in this paper aim at providing an insight into better design of energy-efficient detection approaches in resource-constraint WSNs.

  • 1599.
    Zhou, Shouming
    et al.
    Department of Chemistry, University of Toronto, Toronto, Canada.
    Yeung, Leo W. Y.
    Örebro University, School of Science and Technology. Department of Chemistry, University of Toronto, Toronto, Canada.
    Forbes, Matthew W
    Department of Chemistry, University of Toronto, Toronto, Canada.
    Mabury, Scott
    Department of Chemistry, University of Toronto, Toronto, Canada.
    Abbatt, Jonathan P D
    Department of Chemistry, University of Toronto, Toronto, Canada.
    Epoxide formation from heterogeneous oxidation of benzo[a]pyrene with gas-phase ozone and indoor air2017In: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895Article in journal (Refereed)
    Abstract [en]

    The formation of two classes of epoxide products from the heterogeneous reaction of benzo[a]pyrene (BaP) with gas-phase ozone was demonstrated. BaP was coated on a Pyrex glass tube and oxidized with different concentrations of ozone. After oxidation, the epoxide products were derivatized by N-acetylcystein (NAC) and then analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results show that in addition to mono-epoxides, diol-epoxides were also formed. BaP exposed to genuine indoor air also produces mono- and diol-epoxides, having similar chromatograms to those produced by oxidation of BaP by low concentrations of ozone. Although it is well recognized that diol-epoxides are formed from BaP oxidation in the human body and that they exhibit carcinogenicity via formation of adducts with DNA, this is the first demonstration that such classes of compounds can be formed by abiotic heterogeneous oxidation.

  • 1600.
    Ziad, Ahmad
    Örebro University, School of Science and Technology.
    Hur Lyckes produktionsverktyg kan införa och bibehålla 5S2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Lyckes production tools is a mechanical workshop that manufactures advanced components. Some of their customers are Siemens and Rolls Royce. They work with milling, turning, grinding and polishing. The project takes place in the milling department in Lyckes, where there are four milling stations included in this work. The milling department have no standardization, organized work methods and tools have no fixed location. Operators are experiencing workplace as ineffective. The work has been in use of scientific articles, literature, surveys and interviews to examine the issue in depth. Suggestions on how to implement and maintain the work with 5s have been performed. The project has also shown how 5s affect the process in the operators work and the benefits they can get out of it.

2930313233 1551 - 1600 of 1617
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf