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Plastproduktionen har ökat kraftigt i världen sedan 1950-talet, därmed även förekomsten av plastavfall som ansamlas i naturen. Det pågår flera initiativ på internationell nivå för att förebygga och hantera förekomsten av mikroplast i haven och en viktig aspekt för att minska miljöpåverkan från plastavfall är att öka användandet av bionedbrytbara material. Ett flertal analystekniker är tillgängliga i syfte att analysera nedbrytbarheten hos plaster men då metoderna är många och ibland överlappar har flera studier uppmärksammat behovet av harmonisering och standardisering. Syftet med denna studie var att undersöka bionedbrytning och mikroplastbildning av fyra material; lågdensitet polyeten (LDPE), poly (butylene adipate co-terephthalate) (PBAT), cellulosaacetat och papper. Materialen exponerades i kranvatten, sjövatten och havsvatten med exponeringstid 2 respektive 5 veckor. Materialen analyserades därefter med FTIR, DSC, dragprov och vägning. Konduktivitet och pH kontrollerades på mediet. Valda analystekniker jämfördes med syfte att iaktta dess lämplighet utifrån material och medie. Aspekter som analyserades och diskuterades var nedbrytning utifrån molekylär struktur, utifrån omgivande faktorer samt utifrån nedbrytningens tre faser. Studien visade att cellulosaacetat brutits ned mest under perioden, därefter PBAT. LDPE och papper hade inte brutits ned nämnvärt. Den analysteknik som främst visade på skillnader i nedbrytning var vägning. Resultatet indikerade även att analysteknikernas lämplighet varierade med material samt skede av nedbrytningsprocessen. Vägning, pH-mätning och dragprov var de metoder som tillförde mest i den tidiga fasen av nedbrytningsprocessen. Den skillnad som medierna förväntades utgöra för nedbrytningsprocessen var svår att utläsa baserat på genomförda analyser. / The production of plastics has increased significantly worldwide since the 1950s and a consequence of this is an increase of plastic waste in nature. A number of initiatives are ongoing internationally to prevent and handle the presence of micro plastic in oceans and an increase of biodegradable materials is one important aspect in order to reduce the environmental impact from plastic waste. Today, many techniques are available in order to analyze degradability of plastics. However, they sometimes overlap and a need for standardization and harmonization has been recognized. The purpose of this study was to investigate biodegradability and micro plastic formation inaquatic environments. Low density polyethylene (LDPE), poly (butylene adipate coterephthalate)(PBAT), cellulose acetate and paper have been evaluated. The medium for exposure has been tap water, fresh water and sea water with exposure time of 2 and 5 weeks.The material was analyzed with FTIR, DSC, tensile testing and weight measurement. Additionally, conductivity and pH was measured on the medium. The analytical techniques were evaluated in order to observe their suitability for different material and medium. Aspects that have been discussed and analyzed throughout this paper are degradability based on molecular structure, surrounding factors affecting degradability and the three phases of degradability. The results of this study showed that cellulose acetate degraded the most, thereafter PBAT. LDPE and paper did not indicate any noticeable degradation. Weight measurement gave the clearest indication of degradation. Together with pH measurement and tensile testing; these were the analytical techniques that added the most in the early phase of degradation. Furthermore, the results showed that the suitability of an analytical technique varied with both material and phase of degradation. Additionally, the effect that was expected to be observed based on the different medium was not noticeable within this exposure time.

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Today, structural adhesives are found extensively in load-bearing engineering applications, as their use can be advantageous compared to other fastening methods. However, the characteristics of adhesives are far more complex, making it challenging to predict their behavior in different service conditions. In addition, environmental factors like temperature and water can affect the performance of an adhesive bond both physically and chemically. This work was initiated by MuoviTech AB and aims to evaluate the performance of structural methyl methacrylate adhesives cured in different environmental conditions. The study began with a literature review to find relevant research and literature about structural adhesives, their material characteristics, and the effects of temperature and water on the performance of adhesive bonds. A market survey was conducted to find products suitable for the experiment, and Araldite 2050, Araldite 2051, Permabond TA4200, 3M DP8810NS, LoctiteHY 4070, and Acralock SA 10-05 were selected together with MuoviTech AB. The laboratory work began with sample preparation in terms of abrasion and cleaning of the surface. The adhesives were applied to the samples, and single-lap joints were prepared and cured in room temperature and normal humidity, as well at 5 °C and underwater, for 24 hours. Single-lap shear tests were performed according to American standard ASTM D3163. Lastly, differential scanning calorimetry (DSC) was utilized for the thermal analysis of the samples cured at 5 °C and underwater. The results showed that neither of the adhesives performed in the range specified in the manufacturers’ technical data sheets (TDS). Lower failure strength and elongation was observed for the samples cured at 5 °C and underwater, compared to the samples cured in the optimal condition. However, Loctite HY 4070 showed an increase in failure strength. The DSC analysis revealed various degrees of post-curing. Further investigation with prolonged curing time and more environmental conditions are recommended. New tests for Loctite HY 4070 is also recommended to confirm the results. / Idag finns strukturella lim i stor utsträckning i bärande tekniska applikationer, eftersom deras användning kan vara fördelaktig jämfört med andra fästmetoder. Limmens egenskaper är dock mycket mer komplexa, vilket gör det svårt att förutsäga deras beteende under olika serviceförhållanden. Dessutom kan miljöfaktorer som temperatur och vatten påverka en limbindnings prestanda både fysiskt och kemiskt. Detta arbete initierades av MuoviTech AB och syftar till att utvärdera prestanda för strukturella metylmetakrylatlim härdade under olika miljöförhållanden. Studien inleddes med en litteraturöversikt för att hitta relevant forskning och litteratur om strukturella lim, deras materialegenskaper och effekterna av temperatur och vatten på limförbandens prestanda. En marknadsundersökning genomfördes för att hitta produkter som var lämpliga för experimentet, och Araldite 2050, Araldite 2051, Permabond TA4200, 3MDP8810NS, Loctite HY 4070 och Acralock SA 10-05 valdes tillsammans med MuoviTech AB. Arbetet i laboratoriet inleddes med provförberedelse genom slipning och rengöring av provens yta. Lim applicerades på proverna och förband med enkla överlapp (single-lap) bereddes och härdades i rumstemperatur och normal fuktighet, liksom vid 5 ° C och under vatten, under 24 timmar. Skjuvtester utfördes enligt den amerikanska standarden ASTM D3163. Slutligen användes differentiell svepkalorimetri (DSC) för termisk analys av proverna som härdades vid 5 ° C och under vatten. Resultaten visade att inget av limmen presterade i enlighet med det som beskrevs i tillverkarnas tekniska datablad (TDS). Däremot så observerades en lägre brottstyrka och töjning för proverna som härdades vid 5 ° C och under vatten, jämfört med de prover som härdades i det optimala tillståndet. Loctite HY 4070 visade emellertid en ökning av brottstyrka. DSC-analysen gav indikation på att olika grader av efterhärdning. Ytterligare undersökningar med längre härdningstid och med flera miljöförhållanden rekommenderas. Nya tester för Loctite HY 4070 rekommenderas också för att bekräfta resultaten.

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No description available.

Linker histones (H1) are the basic proteins in higher eukaryotes that are responsible for the final condensation of chromatin. H1 also plays an important role in regulating gene expression. H1 has been described as a transcriptional repressor as it limits the access of transcriptional factors to DNA. Linker histone binds to DNA that enters or exits the nucleosome. Several crystal structures have been published for the nucleosome (histone core/DNA complex), and the interactions of the core histone proteins with DNA are well understood. In contrast the location of the linker histone and its interactions with ds-DNA are poorly understood. In this study we have used isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), and CD spectropolarimetry to determine the thermodynamic signatures and structural changes that accompany H1 binding to ds-DNA. The thermodynamic parameters for the binding of intact linker histones (H1.1, H1.4, and H10) to highly polymerized calf-thymus DNA and to short double stranded DNA oligomers have been determined. We have also determined the thermodynamics for binding of H10 C-terminal tail (H10-C) and globular domain (H10-G) to calf-thymus DNA. The real surprise in the energetics is that the enthalpy change for formation of the H1/DNA complex is very unfavorable and that H1/DNA complex formation is driven by very large positive changes in entropy. The binding site sizes for H1.1, H1.4, and H10 were determined to be 36bp, 32bp, and 36bp respectively. CD results indicate that CT-DNA is restructured upon complexation with either the full length H1 protein (H10) or its C-terminal domain (H10-C). In contrast, the structure of H10 is largely unchanged in the DNA complex. Temperature dependence of enthalpy change, osmotic stress and ionic strength dependence of Ka were tested using ITC. These results indicate that the entropy driven H1/DNA complexes are a result primarily from the expulsion of bound water molecules from the binding interface. This study provides new insights into the binding of linker Histone H1 to DNA. A better understanding of the functional properties of H1 and its interactions with DNA could provide new insights in understanding the role H1 in DNA condensation and transcriptional regulation.

The oncogene c-MYC has guanine-rich and complementary cytosine-rich sequences in its P1 promoter region. The P1 promoter is responsible for over 90% of the c-MYC expression. Downregulation of c-MYC expression represents a novel therapeutic approach to more than 50% of all cancers. A stable i-motif formed by the c-MYC C-rich sequence would be an attractive target for cancer treatment. We have previously shown that c-MYC promoter sequences can form stable i-motifs in acidic solution (pH 4.5-5.5). The question is whether c-MYC promoter sequence i-motif will be stable at physiological pH. In this work, we have investigated the stability of mutant c-MYC i-motif in solutions having pH values from 4 to 7 and containing co-solutes or molecular crowding agents. The crowded nuclear environment was modeled by the addition of polyethylene glycol (PEG, having molecular weights from 200 to 12000 g/mol) at concentrations of 10% to 40% w/w. Circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC) were used to establish the presence and stability of c-MYC i-motifs in buffer solutions having pH values of 4 to 7. The results of these studies are: 1) the addition of up to 20% w/w glycerol does not increase i-motif stability, 2) the addition of 30% PEG results in an increase in i-motif stability to pH values as high as 6.7, 3) i-motif stability is increased with increased PEG concentration and increased PEG molecular weight, and 4) the effects of PEG size and concentration are not linear, with larger PEGs forming DNA/PEG complexes, which destabilize the i-motif. In summary, we have shown that the c-MYC i-motif can exist as a stable structure at pH as high as 6.7 in a crowded environment. Molecular crowding, largely an excluded volume effect, drives the formation of the more compact i-motif, even at higher pH values where the cytosine imino-nitrogen is deprotonated and neutral C-C pairs can form only two H-bonds. Based on this research, it seems possible that a stable c-MYC promoter sequence i-motif could form at physiological pH and would be a reasonable drug target for new cancer therapies.

For a long time, ships have relied on navigators that could figure out their course andlocation based on seeing objects around them. However, this approach is limited to thenavigators’ ability, and with the increasing number of ships, this job becomes harder andharder. With these aspects in mind, the new system, the Automatic identification system(AIS), was created as a tool to help navigators to navigate and increase safety on the sea.AIS is an automatic identification system and is designed to send out information aboutthe vessel and its location. This thesis looks at the state of the art of Automatic identifica-tion systems and Digital selective calling systems to evaluate the security aspects of thesesystems. The thesis aims to investigate if these two systems are susceptible to spoofingattacks and what resources are required for creating successful attacks. Two experimentswere used to achieve this aim and answer the research questions. The first one was to eval-uate the Automatic identification system and test different spoofing attacks on that system.The second experiment was to test different spoofing attacks on the Digital selective callingsystem. Both of these experiments used two software-defined radios for the experiments.The experiment results show that some of the attacks tested on the systems were success-ful, and the attacks tested were successfully executed against the created system. Theseattacks were created and performed using two software-defined radios to send and receivemessages. To conclude, the two systems are susceptible to spoofing attacks. However, anattacker can gain the necessary information to create spoofing attacks on the systems, withvarying consequences and some limitations.

<p> The recrystallization behavior of three Al-Mg-Si-Cu alloys with varying iron and manganese additions was studied by differential power scanning calorimetry under nonisothermal annealing conditions. The influence of cold deformation on the precipitation sequence and its interaction with recrystallization was also investigated. The DSC experiments were complemented by hardness measurements and microstructural studies by optical and electron microscopy. The DSC signals, after optimization of the baseline, were used for the calculation of the kinetic parameters of the recrystallization process. Two different modeling approaches based on global JMAK kinetics were implemented. The first approach utilizes the classical isothermal JMAK expression directly, while the second approach introduces a path variable related to the thermal history of the material in the JMAK description. Model-independent estimates of the activation energy were also evaluated using the Flynn-Wall-Ozawa integral isoconversion method. </p> <p> The results show that the initial stages of recrystallization are not affected by the preceding precipitation processes and recrystallization always follows the precipitation of the Q' phase. However, during recrystallization enhanced coarsening of the Q' phase takes place leading to its transformation to the more stable Q phase. The Q phase exerts a Zener pinning pressures on the migrating boundaries preventing the formation of an equilibrium grain structure. Moreover, for high Fe and Mn additions, discontinuous precipitation of Mg2Si overlaps with the end of recrystallization and exerts an additional pinning pressure on the boundaries. Varying the Fe and Mn content significantly affects the recrystallization kinetics. PSN is promoted in alloys with the higher Fe and Mn content and the recrystallization temperature shifts to lower values. The modeling results show that the recrystallization process conforms to the classical JMAK type behavior. The course of the reaction was reproduced successfully by the path variable approach and the evaluated activation energies were in good agreement with the isoconversional model-independent estimates. However, when the classical JMAK expression was applied directly to non-isothermal measurements, a dependency of the recrystallization process on thermal history was observed. </p> / Thesis / Doctor of Philosophy (PhD)