| 1. |
- Antonsson, Stefan, 1979-
(författare)
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Strategies for improving kraftliner pulp properties
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A large part of the world paper manufacturing consists of production of corrugated board components, kraftliner and fluting, that are used in many different types of corrugated boxes. Because these boxes are stored and transported, they are often subjected to changes in relative humidity. These changes together with mechanical loads will increase the deformation of the boxes compared to the case where the same loads are applied in a static environment. This enlarged creep due to the changes in relative humidity is called mechano-sorptive or accelerated creep. Mechano-sorptive creep forces producers to use high safety factors when designing boxes, and therefore, this is one of the key properties of kraftliner boards. Different strategies to decrease mechano-sorptive creep, and to simultaneously gain more knowledge about the causes for this phenomenon in paper, are the aim of this work. Derivatised and underivatised black liquor lignins, a by-product produced in pulp mills in large quantities, have been used together with biomimetic methods, to modify the properties of kraftliner pulp. Furthermore, the properties of kraftliner pulp have been compared to other pulps in order to evaluate the influence of fibre morphological factors, such as fibre width and shape factor, on the mechano-sorptive creep. In addition the influence of the chemical composition of the kraftliner pulp has been evaluated both by means of treating a kraftliner pulp with chlorite and xylanase and by producing pulps with different chemical composition. By using lignin and biomimetic methods, to create radical coupling reactions, it has been shown that it is possible to increase the wet strength of kraftliner pulp sheets. This method of treating the pulp showed, however, no significant effects on the mechano-sorptive creep. The addition of an apolar suberin-like lignin derivative, which has been shown to be possible to produce from natural resources, did show a positive effect on mechano-sorptive creep properties, but at the expense of stiffness properties in constant climate. Different pulps were compared with a kraftliner pulp and it was observed that the ratio between tensile stiffness and hygroexpansion can be used to estimate the mechano-sorptive creep properties. The hardwood kraft pulps investigated had lower hygroexpansion, probably due to more slender and straighter fibres, and higher tensile stiffness, probably due to lower lignin content. As the lignin content was varied by different methods in kraft pulps, it was observed that increased lignin content gives an increased hygroexpansion and decreased tensile stiffness as well as an increased mechano-sorptive creep. There were also indications of increased mechano-sorptive creep due to higher xylan content.
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| 2. |
- Johansson, Mats J., 1958-
(författare)
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Gas Exchange in the Normal Lung : Experimental studies on the effects of positive end-expiratory pressure and body position
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: The principal function of the lung is gas exchange requiring adequate ventilation and perfusion at the level of the alveoli. The efficiency of gas exchange is depending on the distributions of regional ventilation (V) and pulmonary blood flow (Q) and their correlation.AIMS: To validate a high-resolution method to quantify regional V and to investigate the combined effect of positive end-expiratory pressure (PEEP) and body position on distributions of regional V and Q in the normal lung with mechanical ventilation. To assess the matching of V and Q by calculating ventilation-perfusion ratio (V/Q) heterogeneity, determining the spatial distribution of V/Q and to investigate the role of nitric oxide (NO) in regional V/Q matching.METHODS: Anesthetized mechanically ventilated sheep were studied in prone or supine position with different levels of PEEP (0, 10 and 20 cmH2O). Measurements of regional V were done by determining the deposition of a wet aerosol of fluorescent microspheres (FMS) with a median mass aerodynamic diameter of 1.1 μm, and validated against Technegas. Radioactive microspheres, 15 μm in diameter, were used for determining regional Q. Nitric oxide synthase (NOS) was inhibited with Nω-nitro-L-arginine methyl ester (L-NAME) to evaluate the role of NO on regional V/Q matching. The right lung was dried at total lung capacity and diced in approx. 1000 regions tracking the spatial location of each region.RESULTS: The deposition of FMS mirrored regional deposition of Technegas and thus regional ventilation well. In prone, with PEEP, only a small dorsal redistribution of V but not of Q was observed. The vertical Q gradient was abolished with PEEP in prone position in conflict with the classical zonal model. In supine position both V and Q were distributed with a unimodal gradient and PEEP displaced the mode further dorsally. V/Q heterogeneity was greater in supine than in prone position with and without PEEP. Furthermore, PEEP generated regions with high V/Q in supine but not in prone position. Inhibition of NOS did not change the V/Q distribution in prone position.CONCLUSION: There were marked differences in redistribution of regional ventilation and regional pulmonary blood flow between prone and supine position when PEEP was applied. NO was not an active mechanism for V/Q matching in normal sheep lungs.
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| 3. |
- Johansson, Térèse A., 1978-
(författare)
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Pancreatic Endocrine Tumourigenesis : Genes of potential importance
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Understanding signalling pathways that control pancreatic endocrine tumour (PET) development and proliferation may reveal novel targets for therapeutic intervention. The pathogenesis for sporadic and hereditary PETs, apart from mutations of the MEN1 and VHL tumour suppressor genes, is still elusive. The protein product of the MEN1 gene, menin, regulates many genes. The aim of this thesis was to identify genes involved in pancreatic endocrine tumourigenesis, with special reference to Notch signalling.Messenger RNA and protein expression of NOTCH1, HES1, HEY1, ASCL1, NEUROG3, NEUROD1, DLK1, POU3F4, PDX1, RPL10, DKK1 and TPH1 were studied in human PETs, sporadic and MEN 1, as well as in tumours from heterozygous Men1 mice. For comparison, normal and MEN1 non-tumourous human and mouse pancreatic specimens were used. Nuclear expression of HES1 was consistently absent in PETs. In mouse tumours this coincided with loss of menin expression, and there was a correlation between Men1 expression and several Notch signalling factors. A new phenotype consisting of numerous menin-expressing endocrine cell clusters, smaller than islets, was found in Men1 mice. Expression of NEUROG3 and NEUROD1 was predominantly localised to the cytoplasm in PETs and islets from MEN 1 patients and Men1 mice, whereas expression was solely nuclear in wt mice. Differences in expression levels of Pou3f4, Rpl10 and Dlk1 between islets of Men1 and wt mice were observed.In addition, combined RNA interference and microarray expression analysis in the pancreatic endocrine cell line BON1 identified 158 target genes of ASCL1. For two of these, DKK1 (a negative regulator of the WNT/β-catenin signalling pathway) and TPH1, immunohistochemistry was performed on PETs. In concordance with the microarray finding, DKK1 expression showed an inverse relation to ASCL1 expression.Altered subcellular localisation of HES1, NEUROD1 and NEUROG3 and down-regulation of DKK1 may contribute to tumourigenesis.
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| 4. |
- Göransson, Sara, 1970-
(författare)
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Seeking Individual Health and Organizational Sustainability : The Implications of Change and Mobility
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Extensive changes are taking place in working life and creating new and important areas for research. New knowledge is needed in order for individuals and organizations to be able to maintain long-term development. The aim of this thesis is to increase our understanding of how change and (im)mobility in the labor market are related to employees’ health, wellbeing, and work-related attitudes. The thesis comprises three studies, based on questionnaire data from different samples. Study I examined the potential consequences of downsizing in two organizations that had implemented change in two different ways (proactively and reactively). A proactive approach seems to lessen change-related demands and provide an opportunity for increased participation, which helps lessen the negative effects on employee work attitudes and wellbeing. The descriptive data from a representative sample in Study II revealed that 28 percent of the permanent and 50 percent of the temporary employees did not work in their preferred occupations. The results indicate that those individuals who were involuntarily embedded (locked-in position), especially among the permanent employees, had more health problems and less development at work. Study III utilizes a newly developed construct (work-related health attributions) that focuses on the individual’s perception of the relation between work and health. The results indicate that it seems to be a promising construct for predicting job satisfaction, organizational commitment, and turnover intention. For employees to have the opportunity to participate in organizational change, as well as the opportunity to exercise mobility and alter their circumstances when the organization, occupation, or job is not contributing to their better health appear to be factors that help improve health and sustainability for both employees and organizations.
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| 5. |
- Kanasi, Eleni, 1978-
(författare)
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Molecular analysis of the oral microbiota of dental diseases
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Traditionally, bacterial culture has been used for bacterial detection, allowing study of living microorganisms. Molecular methods are rapid and allow simultaneous identification of numerous species and uncultivated phylotypes. The objective of this doctoral thesis was to investigate the role of the oral microbiota, including poorly characterized and uncultivated bacteria, in dental caries and periodontitis, by comprehensive molecular, clinical, and statistical methods. The microbiota of 275 pre-school children (75 with caries and 200 caries-free) was examined by whole genomic DNA probes, 16S rDNA cloning and sequencing, and PCR. Streptococcus mutans, exhibiting a combined association with Streptococcus sobrinus, was significantly associated with Early Childhood Caries (ECC). Plaque from children with Severe Early Childhood Caries (S-ECC) was diverse with 138 identified and 107 unidentified taxa, which possibly included novel phylotypes. Other species/phylotypes associated with childhood caries included Lactobacillus gasseri (p<0.01), Lactobacillus fermentum, Actinomyces israelii, and Actinomyces odontolyticus (all p<0.05, ECC), Veillonella parvula (p<0.01), Veillonella atypica (p<0.05), and Veillonella sp. HOT-780 (p<0.01, S-ECC). Lactobacillus acidophilus and Lactobacillus reuteri, both used as probiotic therapy species, were detected more frequently in caries-free children than those with ECC. Fastidious periodontal species, including Parvimonas micra, Aggregatibacter actinomycetemcomitans, Eubacterium brachy, Filifactor alocis (all p <0.05), and Porphyromonas gingivalis (p<0.01), were also more frequently detected in children with dental caries than in caries-free children. Other variables associated with ECC were race, dental visit, snacking (all p<0.05), and visible dental plaque (p<0.01). The oral microbiota of early periodontitis in young adults (N=141) was analyzed by whole genomic and oligonucleotide DNA probes, and PCR. Species detected more frequently in early periodontitis than periodontal health included Treponema denticola, F. alocis, Porphyromonas endodontalis, Bacteroidetes sp. HOT-274 (oral clone AU126), and A. odontolyticus (p<0.01) by oligonucleotide DNA probes, and P. gingivalis (p<0.001) and T. forsythia (p=0.03) by PCR. Subgingival samples exhibited a higher prevalence of periodontitis-associated species than samples from tongue surface, including A. actinomycetemcomitans, T. denticola, T. forsythia (all p<0.05), and uncultivated TM7, Treponema, and Actinobaculum clones (all p<0.05). P. gingivalis (p<0.01) by PCR was associated with periodontal disease progression. Early periodontitis was associated with older age (p=0.01), male gender (p=0.04), and cigarette smoking (p=0.05). The role of bacterial subgroups in periodontitis was examined by studying the serotypeability of 313 genotyped clinical A. actinomycetemcomitans isolates (189 subjects). A total of 95 strains (30 subjects) remained non-serotypeable, although PCR revealed presence of the serotype- specific genes. The absence of the immunodominant serotype-specific antigen was confirmed by immunoblot assays. No major DNA rearrangement in the studied serotype-specific gene clusters was found. In summary, detection of previously cultured species and uncultivated phylotypes revealed the diversity of the oral microbiota in dental diseases and health already early in life. Bacterial species have insufficiently characterized subgroups that may have attributes to evade the host response. Molecular approaches used in this study enable comprehensive, culture-independent characterization of the oral microbiome that may in the future lead to identification of diagnostic bacterial profiles for dental diseases.
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| 6. |
- Salehi M., Alireza
(författare)
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Chemical Interactions between Fatty Acids and Wood Components during Oxidation Processes
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fatty acids auto-oxidation on wood is proposed to follow a complex free radical interaction mechanism. The aim of this study was to analyze the effect of wood constituents on oxidation of fatty acids and thereby the entire drying process, and to characterize the fatty acids-wood interaction by using analytical instruments such as RT-IR and NMR.The auto-oxidation process of polyunsaturated fatty acids was analyzed in combination with wood model compounds, softwood and hardwood. The results showed that the oxidative drying process of unsaturated fatty acids was indeed affected by wood constituents. Wood morphology is heterogeneous and porous. A problematic issue in fatty acid-wood system is its heterogeneity and complexity.The most hydrophobic polymer of the main constituents of wood is lignin and it interacted with the oxidation process and lignin structures inhibited or retarded the reaction. However, wood carbohydrates such as lactose and sucrose increased the rate of fatty acids oxidation, thus carbohydrates may function as catalysts.The fatty acids pattern affects not only the structure of the dried oil itself but also the surrounding wood materials. Not only the oil structures were affected but also the lignin was to some extent oxidized as a competing reaction with the oil oxidation. Further, a formation of chemical bonds between the oil and the lignin structures was not observed, i.e. the oils were not immobilized on lignin by covalent bond formation to any significant extent. The analysis on oils in wood using NMR and FTIR demonstrated that highly reactive linoleic acid interacted in wood significantly, while it was not immobilized to the same extent. Oleic acid on the other hand interacted more slowly but was immobilized in the wood structure.A number of wood species (hardwood and softwood) were tested for how they affected the drying process, where Norway spruce dried the fastest and hazelwood the slowest. Generally it appeared to be a connection between high density and slow drying. It can thus be concluded that different wood components affect the oil drying process in different ways. According to the results, it can also be concluded that the structure of the oil and different wood species are crucial in the overall protective performance of the system.
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| 7. |
- Siwale, Workson
(författare)
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Understanding the Influence of Wood Extractives on Off-Gassing during Storage of Wood Pellets
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood pellets have become a solid biomass fuel of choice because they are a standardized product with known quality properties. However, the self-heating and off-gassing tendencies during storage of wood pellets threatens the consistency of the pellets’ quality properties. The aim of this thesis was to increase the body of knowledge towards understanding of the off-gassing of wood pellets. The effects of total wood extractive content and types of extractives in the raw material on off-gassing of wood pellets were investigated through two separate studies. In the first study, the pellets were produced from fresh and pre-treated Scots pine sawdust. The pre-treatments involved storing, extraction and adding additive oils. The second study used synthetic pure cellulose that was pre-treated by adding different additive oils. The pellets were subjected to off-gassing tests under controlled conditions.The results from the first study showed that the total amount of extractives in the raw material has little effect on off-gassing. While gas emissions were reduced for stored and acetone extracted pine pellets, the coefficients of determination (R2) from the linear correlation analysis between off-gassing and the total extractive content of the raw materials were below 0.5 for all the three off-gasses indicating no correlation. The results of cellulose pellets with added additive oils in the second study showed that the off-gassing is highly dependent on the type of extractives in the raw material. The highest mean concentrations of the carbon oxides and methane were recorded from cellulose pellets with added linseed oil. Pellets with added linseed oil had higher off-gas emissions due to the high content of unsaturated fatty acids of 73.9% linolenic and 7.6% linoleic. Based on these results, it was concluded that one of the main causes of off-gassing during storage of wood pellets is the α-oxidation of unsaturated fatty acids. The other notable effect was that methane formation is dependent on anaerobic conditions, whereas formation of carbon oxides can occur both under aerobic and anaerobic conditions.
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| 8. |
- Billinger, Erika, 1986-
(författare)
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Characterization of conjugated protease inhibitors
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall theme of this thesis is a step by step approach for the design and characterization of conjugated protease inhibitors. This involves both a new assay method for protease activity and protease inhibition (paper I), a study of the stoichiometry for protease inhibitor interaction (paper II), design of inhibitory peptides (paper IV) and the construction of inhibitor conjugates (paper III & IV).(I) A model based primarily on erosion in gelatin for protease activity and inhibition studies was designed. The model was also extended to a separate protective layer covering the layer containing the target substrate. A good correlation between protease concentration and rate of erosion was observed. Similarly, increased concentration of inhibitors gave a systematic decrease in the erosion rate. Kinetic analyses of a two-layer model with substrate in the bottom layer displayed a strict dependence of both inhibitor concentration and thickness of the top “protective” layer.(II) The binding stoichiometry between pancreatic proteases and a serine protease inhibitor purified from potato tubers was determined by chromatography-coupled light scattering measurements. This revealed that the inhibitor was able to bind trypsin in a 2:1 complex, whereas the data for a-chymotrypsin clearly showed a limitation to 1:1 complex. The same experiment carried out with elastase and the potato inhibitor gave only weak indications of complex formation under the conditions used.(III) A serine protease inhibitor was extracted from potato tubers and conjugated to soluble, prefractionated dextran or inorganic particles. A certain degree of inhibitory activity was retained for both the dextran-conjugated and particle-conjugated inhibitor. The apparent Ki value of the dextran-conjugated inhibitor was found to be in the same range as that for free inhibitor. The dextran conjugate retained a higher activity than the free inhibitor after 1 month of storage at room temperature. Conjugation to oxide particles improved the heat stability of the inhibitor.(IV) New synthetic Leupeptin analogues, Ahx-Phe-Leu-Arg-COOH & Ahx-Leu-Leu-Arg-COOH, were synthesized with solid-phase peptide synthesis using Fmoc strategy. These tripeptide inhibitors were tight binding inhibitors to the target enzyme trypsin, similar to the natural occurring leupeptin. The phenylalanine containing synthetic analogue was conjugated to inorganic particles and agarose gel beads. In all cases, the inhibitory activity was well preserved.
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| 9. |
- Björk, Anne
(författare)
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Aspects of Vitamin D : Prevalence of deficiency and impact on musculoskeletal parameters
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vitamin D is central in calcium turnover, and adequate levels are important for skeletal health. It is not clear how large contributions from food and sunlight are in Swedish primary care patients, considering the low radiation of UVB in Sweden and fortification of some foods, and whether differences exist between patients of immigrant and Swedish origin. Increasing incidence of osteoporosis-related fractures is a major global health problem. Genetic variations in metabolising enzymes and in the Vitamin D receptor (VDR) have also been shown to be of importance to the overall effect of vitamin D. Polymorphic variation in the gene CYP2R1 encoding the 25-hydroxylase has previously been reported to correlate with circulating levels of 25(OH)D3. Results of association studies between genetic variants of the VDR and muscle strength, as well as falls have been contradictory.The purposes of this thesis were to examine possible differences in plasma-25(OH)D3 levels and intake of vitamin D between Swedish and immigrant female primary care patients, to estimate what foods contribute the most, and to identify contributors to vitamin D status (Paper I-II). Furthermore, the relationship between polymorphisms in the CYP2R1 gene and levels of 25(OH)D3 as well as other biochemical parameters (parathyroid hormone, calcium, phosphate and fibroblast growth factor 23) of skeletal homeostasis, bone mineral density and incidence of fractures was investigated (Paper III). Also, the association between genetic variations in the gene for the vitamin D receptor and measures of muscle strength, physical performance and falls (Paper IV), was investigated by using data from a Swedish multicenter study of elderly men (MrOS).Most important results: Vitamin D deficiency was common, with significant difference between Swedish born and immigrant patients (Paper I). Food intake of vitamin D is associated with circulating vitamin D, but the factors most strongly affecting vitamin D levels were reported sun holiday and origin (Paper II). CYP2R1 polymorphisms are associated with circulating levels of 25(OH)D3 and bone mineral density (Paper III). VDR genetic variants do not appear to have a direct effect on muscle strength or physical performance and incidence of falls in elderly Swedish men (Paper IV).
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| 10. |
- Hansen, Jessica, 1962-
(författare)
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"Så fixade vi Allhallen" : Resursmobilisering och organisationsförtätning i ett lokalsamhälle
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hur går det till att mobilisera människor och resurser i ett svenskt lokalsamhälle? Avhandlingen analyserar hur en idé genom olika slags kontakter, nätverk och människors tillhörigheter i olika organisatioenr frigjorde och skapade tillräckligt med resurser för att bygga en allaktivtetshall. Den visar hur ett organisatoriskt nätverk som går på tvärs mot etablerade intressegrupperingar växer fram och bildar mobiliseringens bas.
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