Browsing by Subject "diffusion"
Now showing items 1-7 of 7
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(2016)Posterior eye segment diseases, such as age-related macular degeneration, are leading causes of preventable visual impairment in the developed countries. Direct intravitreal injections are currently routinely used to deliver therapeutic agents most efficiently to posterior eye segment. Regular injections can however cause ocular complications and some drugs may also be toxic to ocular tissues at high local concentrations of free drug. Different nano-sized particulate systems have been extensively studied as possible drug delivery systems for intravitreal administration offering sustained, local drug action with controlled release. The vitreous gel can form a barrier for diffusion of particles due to its macromolecular structure and composition. Furthermore, ageing and different disease states cause changes in the vitreous structure possibly resulting in shift in the intravitreal movement of particulate systems. In the literature part of this Master's thesis ocular drug delivery is reviewed with main focus on drug targeting in the posterior eye segment. In the experimental work liposomes with different lipid compositions and surface charges were prepared as model particulate systems to evaluate the intravitreal diffusion of nanoparticles with confocal microscope. Furthermore, the influence of aging on the intravitreal diffusion was modeled by enzymatic degradation of the vitreous gel structure. It is discovered that vitreous gel hinders the movement of nanoparticles. Level of hindrance depends on particle's characteristics. 100-200 nm anionic particles move quite freely in the negatively charged vitreous gel. Similarly sized cationic particles are immobile in the vitreous due to electrostatic interactions between surface of the cationic particle and anionic glycosaminoglycans in the vitreous. 1 µm anionic and cationic particles are sterically trapped inside the vitreous meshwork created by the 3-dimensional biopolymer network of the vitreal macromolecules. Vitreous liquefaction increases the diffusion rate of nanoparticles but the clinical impact on ocular pharmacokinetics needs further research.
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(2021)This thesis provides a transnational perspective to Lebanese Kurds, particularly regarding their activism and networks related to Rojava, the Kurdish areas in northern Syria. After Armenians, Kurds form the second-largest non-Arab ethnic group in Lebanon. By estimate, around 100,000-150,000 Kurds reside in Lebanon, most of them holding Lebanese citizenship. Since 2011, the war in Syria has led around 20,000 Syrian Kurds to seek shelter in neighboring Lebanon. In January 2018, Turkey launched an attack against the Kurdish forces in Afrin in northern Syria, which resulted in demonstrations in Kurdish communities worldwide, including Lebanon. The objective of the study was to find out whether, and by which means, Kurds in Lebanon try to influence the Rojava issue and whether they are part of some transnational networks related to Rojava. The primary material of the study is based on five semi-structured interviews conducted with the presidents of four Lebanese Kurdish associations and one unaffiliated Syrian Kurd in Beirut in July 2019. The material was transcribed, and thematic content analysis was used as the method to examine the textual data. The theoretical framework of the research is based on the study of transnational activism, transnational networks, and processes of transnational contention. Furthermore, characteristics of transnational practices of ethnic diasporas, transnational impacts on domestic activism, and transnationalism among the Kurds are presented. The substance of the study is also contextualized by an overview of the history of the Kurds in Lebanon, the recent political developments in northern Syria, the Kurdish women’s movement in Rojava, and media coverage regarding the Kurds in Lebanon. The research found out that the limited political opportunities of the Kurds in Lebanon have weakened their chances to influence the Rojava issue. The community is divided along the borderlines of the Kurdish party political, which affects the attitudes of the Kurds towards Rojava. The transnational networks and processes between Lebanese Kurds and Rojava center on the sympathizers of the PKK leader Abdullah Öcalan. Furthermore, transnational women’s organization networks form the most significant transnational links between Lebanese Kurds and Rojava. Two of the Lebanese Kurdish associations have relations with the women’s umbrella organization Congress Star in northern Syria, and their local activism is largely influenced by the women’s movement in the area. Thus, it is argued that the relationship between the Lebanese Kurds and Rojava is reciprocal.
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(2021)This thesis provides a transnational perspective to Lebanese Kurds, particularly regarding their activism and networks related to Rojava, the Kurdish areas in northern Syria. After Armenians, Kurds form the second-largest non-Arab ethnic group in Lebanon. By estimate, around 100,000-150,000 Kurds reside in Lebanon, most of them holding Lebanese citizenship. Since 2011, the war in Syria has led around 20,000 Syrian Kurds to seek shelter in neighboring Lebanon. In January 2018, Turkey launched an attack against the Kurdish forces in Afrin in northern Syria, which resulted in demonstrations in Kurdish communities worldwide, including Lebanon. The objective of the study was to find out whether, and by which means, Kurds in Lebanon try to influence the Rojava issue and whether they are part of some transnational networks related to Rojava. The primary material of the study is based on five semi-structured interviews conducted with the presidents of four Lebanese Kurdish associations and one unaffiliated Syrian Kurd in Beirut in July 2019. The material was transcribed, and thematic content analysis was used as the method to examine the textual data. The theoretical framework of the research is based on the study of transnational activism, transnational networks, and processes of transnational contention. Furthermore, characteristics of transnational practices of ethnic diasporas, transnational impacts on domestic activism, and transnationalism among the Kurds are presented. The substance of the study is also contextualized by an overview of the history of the Kurds in Lebanon, the recent political developments in northern Syria, the Kurdish women’s movement in Rojava, and media coverage regarding the Kurds in Lebanon. The research found out that the limited political opportunities of the Kurds in Lebanon have weakened their chances to influence the Rojava issue. The community is divided along the borderlines of the Kurdish party political, which affects the attitudes of the Kurds towards Rojava. The transnational networks and processes between Lebanese Kurds and Rojava center on the sympathizers of the PKK leader Abdullah Öcalan. Furthermore, transnational women’s organization networks form the most significant transnational links between Lebanese Kurds and Rojava. Two of the Lebanese Kurdish associations have relations with the women’s umbrella organization Congress Star in northern Syria, and their local activism is largely influenced by the women’s movement in the area. Thus, it is argued that the relationship between the Lebanese Kurds and Rojava is reciprocal.
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(2016)Nanofibrillar cellulose (NFC) can form hydrogels with high water content (> 98 %). It has been studied for drug release, and it has been used as a cell culture matrix, due to its similar structure to extracellular matrix (ECM). In addition it has been found that they has no cytotoxicity. Iontophoresis is the application of an electric current over a defined area for the purpose of enhancing permeation across a membrane for ionized drug species. The aim in the experimental work in this Master's thesis is twofold. First, to find out the suitable drug loading concentrations into NFC hydrogels, which can provide a good release profile, a release study with two model drugs, propranolol and ketoprofen, loaded into three types of NFC hydrogels at three different concentrations, was carried out for this purpose. Second, to see if NFC hydrogels are applicable as a drug reservoir in iontophoretic transdermal drug delivery applications, an iontophoresis study was carried out using porcine ear skin model in vitro for human skin with propranolol loaded into NFC hydrogel of type A. In addition, Stella models were used as an aid to find suitable ways to predict the release and permeation behaviour of models drugs in the abovementioned context. The UPLC results from the release study show for both model drugs, the wt. % released had linear correlation with squareroot of time. At 6 hours, more than 70 wt. % propranolol was released from hydrogel reservoir. For ketoprofen, the release varied between 30 - 87 wt. %, where higher initial loading concentrations produced a decrease in the wt. % released from hydrogel. The iontophoresis study did not show a significant difference between the tested current densities (0.50 mA/cm2; 0.25 mA/cm2) produced on the wt. % of drug released. Simulation models could be run with the mathematical equations for diffusion controlled drug release. In conclusion, the NFC hydrogels show potential as drug reservoir for drug release. Additional experimental data using other types of drug reservoirs should be obtained for a better understanding of the suitability of NFC hydrogels as a drug reservoir in iontophoretic transdermal drug delivery.
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(2015)The thesis starts with a review of literatures related to the topic. In the beginning, several speculations of water holding capacity (WHC) in meat are reviewed, and the joint effects of salt and phosphate addition on WHC are discussed in detail. In addition, the hydrolysis and diffusion of phosphates in meat are also explained. At the end of the literature review, several methods of phosphate measurement are listed and compared. The aim of this research was to determine an effective pattern for phosphate addition in meat processing by studying the dynamics of the phosphate diffusion in relation to their hydrolysis. To address this aim, the meat stripes were subjected to one-dimensional diffusion in TPP and PP brines (with the same salt and P2O5 content), and the phosphate contents of TPP, PP and MP at three diffusion levels (0.625, 1.875 and 3.125 cm) were analysed after 0.5, 2, 6, 24, or 48 h. Thin-layer chromatography (TLC) was used to determine phosphate contents. In addition, the effects of TPP, PP and MP on WHC of the laboratory scale cooked sausages with 0.5 h standing time were compared as a reference for the impact of different phosphates on improving WHC in meat. It was found that areas on the surface of the meat always had the lowest MP content; in addition, in every diffusion level, the initial MP content always decreased first before an increase took place. These results suggested that MP underwent two-way diffusion under the effect of naturally occurring concentration gradient between the meat and the brine, and the TPP/PP hydrolysis generated MP as products. Moreover, PP displayed higher stability then TPP: PP could be observed in the diffusion level as far as at 3.125 cm, and the PP content at 1.875 cm was stable during 2 days’ PP brine diffusion; on the other hand, no TPP was found at distances of 3.125 cm, and only a small amount of TPP was found in 1.875 cm. In addition, the acidic pH accelerated the phosphate diffusion, while the effect of metal ions on diffusivity was unclear. Within the 1.875 cm diffusion distances, which is the common size of meat cube used in meat industry, TPP did not exert a better effect in enhancing or prolonging the stability of PP, and it is possible that the application of PP can fulfil the task of common production schedules. In the sausage WHC test, MP sausages had the worst appearance, which suggests poor protein extraction and hence poor gelling properties. The appearance of PP and TPP sausages were similarly fine, while PP sausages had the best WHC.
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(2017)Syftet för min avhandling var att undersöka spridningen och implementeringen av Trappan-modellen i Finland. I min deskriptiva forskning ville jag få svar på följande frågor: 1) I hur stor omfattning används Trappan-modellen bland de som gått Trappan-utbildningen i Finland? 2) Finns det regionala skillnader i användningsgraden av Trappan-modellen? ‒ Skiljer sig regionerna från varandra med tanke på förutsättningarna för användningen av modellen, och i så fall hur? 3) Vilka faktorer verkar främja och vilka hämma användningen av modellen? Materialet för undersökningen samlades in med en elektronisk webbenkät som innehöll både kvantitativa och kvalitativa frågor. Materialet består av 45 enkätsvar av professionella som gått Folkhälsans Trappan-utbildning under åren 2010 till 2016. Undersökningen var en totalundersökning vars svarsfrekvens var 43,3 %. Materialet analyserades genom s.k. blandad metodologi där både kvantitativa och kvalitativa metoder användes. Den kvantitativa analysen bestod av beskrivande univariat statistik, samt bi- och multivariat analys i korstabeller, eftersom materialet var för litet för statistiska sambands-/signifikanstest. I den kvalitativa analysen användes både allmän innehållsanalys med tematiska indelningar och teoristyrd inne-hållsanalys. Det våldsförebyggande arbetet i Finland utgör kontexten för forskningen. Trappan-modellens spridning och användning analyserades i termer som härrör sig från teorier om diffusion av innovationer och implementering. Bland respondenterna har Trappan-modellen använts i relativt hög grad efter utbildningen. Regionala skillnader både i användningen och i förutsättningarna för användningen av Trappan-modellen verkar förekomma. Faktorer som verkar påverka användningen och implementeringen kunde urskiljas och diskuteras i avhandlingen. Användning av blankett för screening av våld eller förekomsten av handlings¬planer på arbetsplatserna verkar ha ett positivt samband med användning av Trappan. Det våldsförebyggande arbetet behöver vara strukturerat och planerat i regionen och Trappan-arbetarna behöver ha stöd av både förmannen och sina kolleger på sin egen arbetsplats. Modellen verkar inte vara förankrad i de politiska besluten på högre nivå. Denna avhandlings slutsats är att Trappan-modellen inte implementeras effektivt som en ”ensam” insats, utan den behöver utgöra en del av strukturerat och koordinerat våldsförebyggande arbete.
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(2017)Syftet för min avhandling var att undersöka spridningen och implementeringen av Trappan-modellen i Finland. I min deskriptiva forskning ville jag få svar på följande frågor: 1) I hur stor omfattning används Trappan-modellen bland de som gått Trappan-utbildningen i Finland? 2) Finns det regionala skillnader i användningsgraden av Trappan-modellen? ‒ Skiljer sig regionerna från varandra med tanke på förutsättningarna för användningen av modellen, och i så fall hur? 3) Vilka faktorer verkar främja och vilka hämma användningen av modellen? Materialet för undersökningen samlades in med en elektronisk webbenkät som innehöll både kvantitativa och kvalitativa frågor. Materialet består av 45 enkätsvar av professionella som gått Folkhälsans Trappan-utbildning under åren 2010 till 2016. Undersökningen var en totalundersökning vars svarsfrekvens var 43,3 %. Materialet analyserades genom s.k. blandad metodologi där både kvantitativa och kvalitativa metoder användes. Den kvantitativa analysen bestod av beskrivande univariat statistik, samt bi- och multivariat analys i korstabeller, eftersom materialet var för litet för statistiska sambands-/signifikanstest. I den kvalitativa analysen användes både allmän innehållsanalys med tematiska indelningar och teoristyrd innehållsanalys. Det våldsförebyggande arbetet i Finland utgör kontexten för forskningen. Trappan-modellens spridning och användning analyserades i termer som härrör sig från teorier om diffusion av innovationer och implementering. Bland respondenterna har Trappan-modellen använts i relativt hög grad efter utbildningen. Regionala skillnader både i användningen och i förutsättningarna för användningen av Trappan-modellen verkar förekomma. Faktorer som verkar påverka användningen och implementeringen kunde urskiljas och diskuteras i avhandlingen. Användning av blankett för screening av våld eller förekomsten av handlingsplaner på arbetsplatserna verkar ha ett positivt samband med användning av Trappan. Det våldsförebyggande arbetet behöver vara strukturerat och planerat i regionen och Trappan-arbetarna behöver ha stöd av både förmannen och sina kolleger på sin egen arbetsplats. Modellen verkar inte vara förankrad i de politiska besluten på högre nivå. Denna avhandlings slutsats är att Trappan-modellen inte implementeras effektivt som en ”ensam” insats, utan den behöver utgöra en del av strukturerat och koordinerat våldsförebyggande arbete.
Now showing items 1-7 of 7