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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Utveckling av 2D-gelelektrofores för alkaliska proteiner i Ideonella dechloratans : En jämförelse mellan aeroba och anaeroba odlingsförhållanden / Development of 2D-gel electrophoresis for alkaline proteins in Ideonella dechloratans : A comparison between aerobic and anaerobic culture conditions

Lorenz, Elin January 2013 (has links)
De flesta klorater som finns i naturen kommer från utsläpp av människan i flera storaindustrier. Kloraterna påverkar flera olika levande organismer och det är därför viktigt att tahand om dem efter utsläppen. Flera olika bakterier kan bryta ned klorat till klorid och syre, enav dessa är Ideonella dechloratans. Nedbrytningen sker med de alkaliska enzymernakloratreduktas och kloritdismutas under anaeroba förhållanden. I detta arbete har 2Dgelelektrofores utvecklats för alkaliska proteiner i Ideonella dechloratans i syfte att kunnajämföra proteinuttryck under olika odlingsförhållanden. Därefter har en jämförelse mellanaeroba och anaeroba odlingsförhållanden gjorts samt försök att detektera kloritdismutas.Resultatet har blivit att en metod har tagits fram som ger en hög grad av upplösning pågelerna från 2D-gelelektroforesen. Jämförelserna mellan aeroba och anaerobaodlingsförhållanden har visat att det finns stora skillnader i proteinuttryck mellan de bådaodlingsförhållandena. Fler proteiner syns i området pH 8-10 under anaerobaodlingsförhållanden jämfört med aeroba förhållanden. Försök till identifiering avkloritdismutas har gjorts för de anaeroba odlingsförhållandena, dock krävs det ytterligarearbete innan en säker identifiering kan göras.
22

Hur har digitaliseringen i skolan förändrat kemiundervisningen i årskurs 7-9? : En jämförelse mellan forskning och praktik

Andersson, Ida January 2018 (has links)
I den reviderade variation av LGR 11 (Läroplan för grundskolan, förskoleklassen ochfritidshemmet 2011) från 2017 lyfts digitaliseringen fram. Skolan är under förändringoch digitala verktyg finns i klassrum. Eleverna förväntas använda dessa och utvecklaförmågor som lyfts fram i LGR 11 och utveckla kunskaper om hur de ska förhålla sigtill ett konstant informationsflöde. Samtidigt använder lärare redan idag många digitalaverktyg i sin undervisning. Med de förändringar som gjorts markerar myndigheter iSverige vikten av att eleverna lär sig navigera och hantera den digitala världen.Frågan som då måste ställas är hur det ser ut i klassrum i Sverige och hurdigitaliseringen har påverkat undervisningen i kemi. När datorn gjorde entréförändrades klassrummet men det tog tid. Idag finns det en mängd olika digitalaverktyg att använda. Genom att gå ut och intervjua lärare skapades en bild avsituationen i det digitala kemiklassrummet. De arbetade med digitala böcker,interaktiva övningar och formativ feedback via delade dokument. Digitaliseringen iskolan speglar den utveckling som samhället har tagit och det är viktigt att alla få följamed i den utvecklingen.Det har även bedrivits forskning inom digitaliseringen i skolan där begrepp som digitalläsning återfinns. Hur har undervisningen hanterats i förhållande till den forskningsom finns och hur lyfter digitaliseringen undervisningen? Genom att göra en jämförelsemellan forskning och praktik skapas en bild av hur det ser ut i skolor men också varmöjligheter för utveckling ligger.
23

Contribution of polyfluoroalkyl phosphate esters (PAPs) and other precursor compounds to perfluoroalkyl carboxylates (PFCAs) in humans and the environment

Eriksson, Ulrika January 2016 (has links)
Per-and polyfluoroalkyl substances (PFAS) are anthropogenic compounds that have been spread all over the world. The use of fluorotelomer compounds, short-chained homologues, and other PFASs with perfluorinated moieties has emerged recent years. One of these emerging compound classes is polyfluoroalkyl phosphate esters (PAPs), which have the ability to degrade into persistent PFCAs. The aim of this thesis was to assess the contribution of PAPs and other precursors to the exposure of PFCAs to humans and the environment. The main objective was to analyze a wide range of PFAS in human serum, wild bird eggs, indoor dust, waste water, and sludge. There was a significant contribution from selected precursors to the total amount of PFASs in the abiotic compartments indoor dust, waste water, and sludge. Levels of PAPs found in house dust exceeded those of PFCAs and perfluorosulfonic acids (PFSAs), revealing PAPs as a world-wide important exposure source. A net increase was during waste water treatment was observed for several PFASs in Swedish waste water treatment plants. Together with presence of precursor compounds and intermediates in the influent water and the sludge, this suggest that degradation of PFCA precursors contributed to the increase of PFCAs. Detection of precursors in human serum, together with slow declining trends of PFCAs, revealed an ongoing exposure of PFCAs to the general population of Australia. The diPAPs and the FTSAs were also detected in raptor bird eggs from Sweden from both the terrestrial and the freshwater environment. The precursors concentrations and patterns observed reveal that current regulatory measures are insufficient for the purpose of protecting humans and the environment from PFASs exposure.
24

Identification and characterization of protein-protein interactions in the nuclear envelope

Vijayaraghavan, Balaje January 2017 (has links)
The nuclear envelope forms the interface between the nucleus and the cytoplasm. The nuclear envelope consists of the two concentric lipid membranes, the nuclear pores and the nuclear lamina. The inner nuclear membrane contains hundreds of unique transmembrane proteins showing high tissue diversity. Mutations of some proteins in the nuclear envelope give rise to a broad spectrum of diseases called envelopathies or laminopathies. In this thesis, I aimed to study the functional organization of the nuclear envelope by identifying and characterizing interactions between the nuclear envelope proteins. For this, we developed a novel method called the Membrane Protein Crosslink Immuno-Precipitation, which enable identification of protein-protein interactions in the nuclear envelope in live cells. We identified several novel interactions of the inner nuclear membrane protein, Samp1, and studied the interaction between the Samp1 and the nuclear GTPase, Ran in detail. Samp1 can bind to Ran and is thus the first known transmembrane Ran binding protein and Samp1 might provide a local binding site for Ran in the inner nuclear membrane. We found that Samp1 also binds to the inner nuclear membrane protein, Emerin and Ran can regulate the Samp1-Emerin interaction in the nuclear envelope. During mitosis, Samp1 distributes in the mitotic spindle. Therefore, we investigated a possible functional role of Samp1 in the mitotic machinery. Samp1 depletion resulted in aneuploid phenotypes, metaphase prolongation and decreased distribution of γ-tubulin and β-tubulin in the mitotic spindle. We found that Samp1 can bind to γ-tubulin, which is essential for the microtubule nucleation and hence for the spindle stability. The new interesting features of Samp1 provide insights on the unforeseen functions of the nuclear envelope proteins. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
25

Electrochemical investigation of "green" film-forming corrosion inhibitors : / Elektrokemisk undersökning av "grön" filmbildande korrosionsinhibitorer :

Wang, Hansheng January 2011 (has links)
In this work, a comparative electrochemical study has been performed to evaluate corrosion inhibition property of several film-forming corrosion inhibitors provide by Akzo Nobel on carbon steel in a chloride solution. For carbon steel exposed to 1 M NaCl solution with and without added inhibitor, electrochemical measurements including electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) at different exposure time intervals, and potentiodynamic polarization at the termination of the exposure, have been performed to investigate the film forming process and to evaluate corrosion inhibition efficiency of the inhibitors, as well as its evolution with time. The corrosion resistance data obtained from the EIS and LPR measurements are in good agreement. The results indicate different inhibition properties of the inhibitors tested. The inhibition effect of SSF CI-1 is negligible in the first hour of exposure, but it increases steadily with time for 1 day, and then remains the same level during the exposure up to one week. SSF CI-2 exhibits a good inhibition effect in the first hour, but the effect decreases with time to a low level after 8 hours, and then increases again with prolonged exposure. SSF CI-4 shows a low inhibition effect during the first day, and then increases to a maximum level after three days’ exposure. For SSF CI-5 and SSF CI-6, the inhibition effect within 8 hours is relative low but higher than that of SSF CI-4, and the effect increases with time during prolonged exposure. The SSF CI-5 seems to be better than SSF CI-6 because of a more stable inhibition effect. The EIS results indicate that most of the inhibitors form a resistive surface film on carbon steel, which becomes more resistive and protective after several days’ of exposure. However, in the initial stage of exposure, the SSF CI-6 does not show an effect of formation of a resistive film on the surface. The potentiodynamic polarization measurements suggest that, SSF CI-1 and SSF CI-2 are anodic type inhibitor, SSF CI-4 is cathodic type inhibitor, and SSF CI-5 and SSF CI-6 are mix type inhibitor. Moreover, the inhibitors tested show a similar corrosion inhibition effect as mussel adhesive protein (MAP) at the low dosage level.
26

Metal release of stainless steel particles in artificial lung fluid: complexation and synergistic effects / Frigörelse av metaller från partiklar av rostfritt stål i artificiell lungvätska: komplexering och synergieffekter

Liu, Yi January 2011 (has links)
Numerous metal release data have been published by the Div. Surface and Corrosion Science and the AISI 316L stainless steel particles’ behavior in artificial lysosomal fluid (ALF). This study aims to evaluate the effect of chemical components in ALF on metal release from stainless steel particles with a bottom-up methodology. Two sizes of 316L stainless steel particles were used to assess the particle size influence on the metal release in detail. The results show that organic complexing agents e.g. lactate, tartrate and citrate are responsible for the high metal release rate in ALF. Correlations between the metal release rate and the number of carboxyl groups of the organic ligand were observed. Moreover, metal release data in this study indicates no synergistic effects in ALF solution, and continued research is on-going to study the synergistic effects further. No quantitative rules of iron, chromium and nickel release from the same stainless particles could be found which may indicate that these metals are released through different pathways e.g. diffusion or chemical dissolution. In different solutions with different chemical components, one or more metal release mechanisms dominate over others and make the metal release rate unpredictable.
27

Radiation induced corrosion of copper / Strålningsinducerad korrosion av koppar

Björkbacka, Åsa January 2011 (has links)
The Swedish concept for storage of highly radioactive spent nuclear fuel is called the KBS-3 program. The proposed procedure is that the waste will be stored in a deep repository, 500 meters down in the Swedish bedrock, for 100 000 years. The fuel will be sealed inside cast iron cylinders surrounded by copper. The iron-copper canisters will then be placed one by one in holes and embedded in bentonite clay. The environment in the deep repository will be that of an underground rock cave, there will be groundwater and low amounts of oxygen present. Substances which are likely to react with the copper canister and cause corrosion are oxygen, sulphides and reactive water radiolysis products. Gamma radiation from the spent nuclear fuel will penetrate through the canister and further into the bentonite clay. When the gamma radiation comes in contact with the water in the bentonite clay, water radiolysis will occur. Corrosive radiolysis products are for example hydroxyl radicals, solvated electrons and hydrogen peroxide. The main purpose of this work was to study the effect of gamma radiation on copper pieces, in an aqueous environment, both under oxic and anoxic conditions. The surfaces of the copper pieces were characterized using scanning electron microscopy (SEM) and infrared absorption spectroscopy (IRAS). The dissolution of copper was measured using inductively coupled plasma spectroscopy (ICP). A second study was also performed where the reactions of three different oxidants; hydrogen peroxide, permanganate and iridium hexachloride, were studied in the presence of copper in an inert environment. All of the reactions were studied spectrophotometrically and the dissolution of copper was measured using inductively coupled plasma spectroscopy (ICP). The SEM measurements showed corrosion products on the irradiated copper pieces both under oxic and anoxic conditions. Under anoxic conditions the corrosion products had a center of a small cavity which was surrounded by a larger, flat, circular area. From that area, wider cavities were spreading out in apparently random directions. SEM-EDS measurements detected oxygen on the surface of the corrosion products. ICP measurements of the water phase showed that the water from irradiated samples contained higher levels of copper than unirradiated samples. ICP measurements from the reactions of copper in the presence of oxidants showed that copper was only dissolved in the presence of iridium hexachloride. These results show that gamma radiation causes corrosion of copper in an aqueous environment, both under oxic and anoxic conditions. It can also be concluded that hydrogen peroxide is not the radiolysis product that causes the dissolution of copper when copper is irradiated in an aqueous and inert environment.
28

Motivation i Kemiundervisningen : Vilka metoder kan lärare använda för att väcka intresse och öka elevernas motivation för kemiämnet ? / Motivation in Chemistry teaching : What methods can teachers use to arouse interest and increase students' motivation for the subject of chemistry?Wafaa Mahmood

Mahmood, Wafaa January 2022 (has links)
Syftet med denna studie är att undersöka utifrån ett lärarperspektiv vilken roll kemiläraren har för att stärka elevers motivation,samt belysa hur läraren bedriver undervisning i ämnet som hjälper eleverna att bli motiverade i kemiämnet. Undersökningen genomfördes  med fem kemilärare på högstadiet i två grundskolor i södra Sverige. Denna studie bygger på den kvalitativa metoden där semistrukturerade intervjuer har använts som redskap för att samla in impirin.
29

Tillverkning av kalibrerstandard förämnesbestämning i kärnbränslen / Fabrication and calibration standards for evaluation ofnuclear fuels

Lundell, Isak, Ekman, Sven January 2023 (has links)
The test production of a simulated nuclear fuel, possible to use as a calibration standard was donethru dissolving the preferred dopant-metals in a nitric-salt into weak acid. This solution wasmixed with dissolved uranium-salt to aimed concentration. This was precipitated by rising pHforming metallic-hydroxide.The precipitated salt was dried in an reduction gas, pressed to pellets and sintered in oven. Thequality of the pellets and its content was evaluated thru comparing theoretical and measureddensity, ICP-MS for which ground elements and which concentration of these forming thepellets. XRD was used to evaluate formed associated ground-elements and the lattice parameters.Finally, SEM was used to evaluate how homogenous the distribution of the doped elementsturned out.There are still a variety of tests yet to perform in order to create a high quality calibrationstandard. Our preparation of dissolved metallic salts will hopefully be usable for any furtherexperimentalist in this field. The single-doped calibration-standards are aimed to be used byStudsvik to calibrate their Lazer Ablation Inductivity coupled Plasma Mass Spectrometryinstrument.
30

Integrating membrane filtration forwater reuse in tissue mill

Moslehi, Ehsan January 2018 (has links)
Water is an essential and indispensable component is the pulp- and paper production industry.The increase in energy costs, stricter environmental regulations and water resource shortageshave caused a reduction of the water footprint in the industry as well as an increase in waterrecycling and water circuit closure. Reducing water usage requires an understanding of wherecontaminants originate, as well as which streams are critical to the process and how they impactmill operation. The recirculation of water can cause contaminant accumulation; therefore millsemploy technologies for water treatment in the internal water cycles, the so-called ‘kidneys’.Application of membrane technology is one such option which can improve the recycled waterquality and reduce contaminant buildup.The present study was carried out on a lab-scale for the treatment of a tissue mill effluent usingmembrane separation. A combination of pretreatment methods and various membranes werecompared with regards to separation, flux and fouling. The AlfaLaval M20 device was to treatwastewater samples sent from the mill, where the permeate was recirculated to the feed tank.COD and TOC levels are compared with regards to determining the separation efficiency. Thepermeate flux was measured over the two-hour filtration period, as well as flux recovery todetermine fouling levels. Additionally, some economic aspects of the process are discussed.This study suggests the potential application of a combination of flocculation or centrifugationpretreatment, with reverse osmosis membranes for recycling water to replace freshwater intake.The results also indicate the possibility of using ultrafiltration as kidneys to decreasecontamination buildup for further water loop closure.

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