132 research outputs found
Karakterisering af vesikler ved dynamisk lysspredning
No full textFormålet med projektet er at undersøge alkohols indvirkning på brudstyrken (lysis ten- sion) af DMPC-vesikler. Ved at ekstrudere multilamellare vesikler opnår vi en monodis- pers opløsning af unilamellere vesikler. Ved at variere mængden af alkohol i membranen forventer vi en ændring af brudstyrken. En model for ekstruderingsprocessen foreslår, at denne ændring vil give anledning til en ændret størrelse af de ekstruderede vesikler. Vi måler den hydrodynamiske radius af vesiklerne med dynamisk lysspredning. Da vi har haft eksperimentelle problemer med systematiske fejl og usikkerheder, er vi ud fra vores resultater ikke i stand til at sige noget generelt om alkohols betydning for brud- styrken. Vi er derfor ikke i stand til at eftervise den foreslåede model. Vi diskuterer, på baggrund af vores eksperimentelle vanskeligheder, fejlkilder og usikkerheder med det formål at videregive erfaringer om forsøg med dynamisk lysspredning.Formålet med projektet er at undersøge alkohols indvirkning på brudstyrken (lysis ten- sion) af DMPC-vesikler. Ved at ekstrudere multilamellare vesikler opnår vi en monodis- pers opløsning af unilamellere vesikler. Ved at variere mængden af alkohol i membranen forventer vi en ændring af brudstyrken. En model for ekstruderingsprocessen foreslår, at denne ændring vil give anledning til en ændret størrelse af de ekstruderede vesikler. Vi måler den hydrodynamiske radius af vesiklerne med dynamisk lysspredning. Da vi har haft eksperimentelle problemer med systematiske fejl og usikkerheder, er vi ud fra vores resultater ikke i stand til at sige noget generelt om alkohols betydning for brud- styrken. Vi er derfor ikke i stand til at eftervise den foreslåede model. Vi diskuterer, på baggrund af vores eksperimentelle vanskeligheder, fejlkilder og usikkerheder med det formål at videregive erfaringer om forsøg med dynamisk lysspredning
An experimental study of the DMPC perturbated with stearic acid: En eksperimentiel undersøgelse af DMPC perturberet med stearinsyre
No full textThis project deals with an experimental study of the DMPC perturbated with stearic acid in growing Mole fractions dissolved in Milli-Q water. This study is motivated by the article \textit{ Effect of Fatty Acid Inclusion in a DMPC Bilayer Membrane} see Peters et al. In addition, examined whether there is a markedly change in repeatlength for samples with a pH around 7(protonated), respectively, over 9(deprotonated). It concludes that there is a systematic change in repeatlength as a function of mole fraction. This change can only be seen effective for mole fraction up to 10 \%. For mole fraction over 10 \% is not enough MLV to intensityspectrum gives well-defined Bragg-peaks. This may be because we only measured over 30 minutes. It is also concluded that there is a clear difference in repeatlength between the protonated and deprotonated samples. This difference is slightly larger than the 2-3 Å as predicted by Peters et al.This project deals with an experimental study of the DMPC perturbated with stearic acid in growing Mole fractions dissolved in Milli-Q water. This study is motivated by the article \textit{ Effect of Fatty Acid Inclusion in a DMPC Bilayer Membrane} see Peters et al. In addition, examined whether there is a markedly change in repeatlength for samples with a pH around 7(protonated), respectively, over 9(deprotonated). It concludes that there is a systematic change in repeatlength as a function of mole fraction. This change can only be seen effective for mole fraction up to 10 \%. For mole fraction over 10 \% is not enough MLV to intensityspectrum gives well-defined Bragg-peaks. This may be because we only measured over 30 minutes. It is also concluded that there is a clear difference in repeatlength between the protonated and deprotonated samples. This difference is slightly larger than the 2-3 Å as predicted by Peters et al
Understanding the concept of interdisciplinarity within the natural sciences
No full textThis project aimed to understand the concept of interdisciplinary research within natural sciencesand its potential place in future of natural sciences. The focus of the report is in establishing a vocabulary associated with interdisciplinary research, complemented with examples from everyday life togain a deeper understanding of the terms. There are examples of important research breakthroughsin scientific history, as well as some relevant examples of today’s interdisciplinary collaborations thatled to beneficial discoveries. The report also introduces interdisciplinary assessment criteria andbrings light on the intricacy surrounding the terminology and the challenges in definitively categorizing something as ’interdisciplinary’. Dedicated sections discuss Roskilde University’s characterizationas an interdisciplinary university and the reasoning behind its interdisciplinary nature. To providea clearer and more tangible illustration of interdisciplinary work, the report introduces a case studycentred on a Ph.D. programme currently taking place at Roskilde University. Combining mathematical modelling and biology, this case study offers a concrete example of how interdisciplinaryapproaches are applied in academic research. The study was conducted by interviewing four individuals each having a distinct role related to this Ph.D. project. This included the Dean of NaturalSciences at RUC who specifically allowed grants for Ph.D. projects focusing on interdisciplinary research, the project’s two supervisors, one from mathematical and one from biological background,and finally, the Ph.D. student working on the project. The analysis of the case study involves applying the knowledge acquired during the report writing process and comparing the experiences fromthe interviewees with the expectations derived from the project writing on interdisciplinary research.This case study offered insights into practical implementation of interdisciplinary practices, theiradvantages and challenges, and ultimately helped us in drawing a final conclusion
Optimising the thickness determination of homopolymers and diblock copolymers using optical spectral reflectance during solvent vapour annealing
No full textIn this thesis, the solvent vapour annealing of the homopolymers polystyrene and polyisoprene thin films and the diblock copolymer polystyrene-b-polyisoprene thin film have been investigated using the experimental technique optical spectral reflectance and the thickness of the thin films have been modelled using the Fresnel equations. The layered model consists of an ambient with a refractive index, a homogeneous thin film with a refractive index and thickness, a silicon oxide layer fixed at \SI{2}{\nano\meter} and a silicon wafer. Both the silicon oxide layer and silicon wafer have refractive indices and have been taken from Ocean Optics Nano-Calc software \cite{nanocalcmanual}. A fitting protocol has been implemented using the mean square error and three values are fitted per measurement, the refractive index for the ambient, the refractive index for the thin film and the thickness of the thin film. The modelling and fitting for the homopolymers polystyrene and polyisoprene seem optimal whereas when applied to the polystyrene-b-polyisoprene thin film the modelling is suboptimal
Influence of Stick-slip effect and vaporization of liquids on measured surface energy
No full textThis project is an investigation of how one measures the surface energy of a solid. We presentthree methods of deriving the surface energy of a solid by measuring the angle that the liquiddroplets make when they are in contact with the solid being measured. This angle changes as theliquid evaporates. We describe this change in angle as being caused by the evaporation removingmass but the interactions between the liquid and the solid can be too strong for the liquid tocontract smoothly over the surface, keeping the droplet anchored to the surface. We implementa two-component model from the surface energy methods, into a model for this anchoring effect.To analyse our data we develop a model that describes how a spherical cap shaped dropletwill evaporate, assuming the heat entering the droplet is proportional to its surface area whichis in contact with the vapor as it either sticks to the surface, slides or some combination of thetwo. It is not clear from our data how much of an effect the two-component model has on theanchoring of liquids. The model describing the mass loss can be used to describe the environmentaleffects on a given experiment. If a suitable pair of solid and liquid can be found, theamount of stick and slippage of a droplet can be found
Systematisk analyse og opdeling af argumenterne i genteknologidebatten: Systematic analyses and classification of the arguments in the debate about gene technology
No full textVi har undersøgt fordelene ved at inddele argumenter fra genteknologidebatten, med henblik på at give et struktureret indblik i denne. Med udgangspunkt i artiklen ”Moralen som teknologiens nidkære grænsedrager” af Kasper Lippert-Rasmussen, har vi udarbejdet en model til at kategorisere argumenter i den offentlige genteknologidebat. Modellen indeholder fire argumenttyper; risiko, økonomi, værdi og rettighed. For at give et struktureret indblik i debatten, udvalgte vi argumenter der repræsenterer et bredt spektrum indenfor hver af de fire argumenttyper. Vi har analyseret og forsøgt at konkludere på holdbarheden af disse argumenter enkeltvis. Ud fra analyserne, har vi udledt, at det er problematisk at konkludere noget generelt om argumenttyperne og at man derfor bør vurdere argumenterne hver for sig. Problematikken består i, at mange argumenter ofte indeholder aspekter fra flere af argumenttyperne, og derved gør grænserne mellem typerne flydende. Vi mener dog alligevel, at en model over argumenttyper i genteknologidebatten er nyttig, da det giver et godt udgangspunkt for diskussionen af et argument. Dette gør det lettere at sætte sig ind i enkelte argumenter og hvilke aspekter disse indeholder. Abstract We have examined the advantages of classifying different arguments from the debate about gene technology, with the goal to give a structured insight in to this discussion. Using the article, “Moralen som teknologiens nidkære grænsedager” by Kasper Lippert-Rasmussen, as a starting point, we have devised a model to categorize arguments in the public debate about gene technology. The model consists of four argument types; risk, economy, value and rights. In order to give a structured view into the debate, we have picked out arguments which represent a broad spectrum of views within the four types of arguments. We have analyzed and tried to conclude on the strength of these arguments separately. On the basis of these analyzes we have summed up that each argument has to be considered separately, because it is hard to conclude anything general about the argument types. We think this is the case because an argument often contains aspects of several arguments types, which makes the boundaries between the arguments vague. In spite of this, we still think that a model covering the argument types in the debate about gene technology is useful, because it gives a good basis for a discussion about an argument. This makes the single arguments easier to understand and to figure out which aspects they contain.Vi har undersøgt fordelene ved at inddele argumenter fra genteknologidebatten, med henblik på at give et struktureret indblik i denne. Med udgangspunkt i artiklen ”Moralen som teknologiens nidkære grænsedrager” af Kasper Lippert-Rasmussen, har vi udarbejdet en model til at kategorisere argumenter i den offentlige genteknologidebat. Modellen indeholder fire argumenttyper; risiko, økonomi, værdi og rettighed. For at give et struktureret indblik i debatten, udvalgte vi argumenter der repræsenterer et bredt spektrum indenfor hver af de fire argumenttyper. Vi har analyseret og forsøgt at konkludere på holdbarheden af disse argumenter enkeltvis. Ud fra analyserne, har vi udledt, at det er problematisk at konkludere noget generelt om argumenttyperne og at man derfor bør vurdere argumenterne hver for sig. Problematikken består i, at mange argumenter ofte indeholder aspekter fra flere af argumenttyperne, og derved gør grænserne mellem typerne flydende. Vi mener dog alligevel, at en model over argumenttyper i genteknologidebatten er nyttig, da det giver et godt udgangspunkt for diskussionen af et argument. Dette gør det lettere at sætte sig ind i enkelte argumenter og hvilke aspekter disse indeholder. Abstract We have examined the advantages of classifying different arguments from the debate about gene technology, with the goal to give a structured insight in to this discussion. Using the article, “Moralen som teknologiens nidkære grænsedager” by Kasper Lippert-Rasmussen, as a starting point, we have devised a model to categorize arguments in the public debate about gene technology. The model consists of four argument types; risk, economy, value and rights. In order to give a structured view into the debate, we have picked out arguments which represent a broad spectrum of views within the four types of arguments. We have analyzed and tried to conclude on the strength of these arguments separately. On the basis of these analyzes we have summed up that each argument has to be considered separately, because it is hard to conclude anything general about the argument types. We think this is the case because an argument often contains aspects of several arguments types, which makes the boundaries between the arguments vague. In spite of this, we still think that a model covering the argument types in the debate about gene technology is useful, because it gives a good basis for a discussion about an argument. This makes the single arguments easier to understand and to figure out which aspects they contain
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