Heterogeneous Ziegler-Natta catalysts are responsible for most of the industrial production of polyethylene and polypropylene. A unique feature of these catalysts is the presence of more than one active site type, leading to the production of polyolefins with broad distributions of molecular weight (MWD), chemical composition (CCD) and stereoregularity. These distributions influence strongly the mechanical and rheological properties of polyolefins and are ultimately responsible for their performance and final applications. The inherent complexity of multiple-site-type heterogeneous Ziegler-Natta catalysts, where mass and heat transfer limitations are combined with a rather complex chemistry of site activation in the presence of internal and external donors, plus other phenomena such as comonomer rate enhancement, hydrogen effects, and poisoning, makes the fundamental study of these systems a very challenging proposition. In this research project, new mathematical models for the steady-state and dynamic simulation of propylene polymerization with Ziegler-Natta heterogeneous catalysts have been developed. Two different modeling techniques were compared (population balances/method of moments and Monte Carlo simulation) and a new mechanistic step (site transformation by electron donors) were simulated for the first time. Finally, polypropylene tacticity sequence length distributions were also simulated. The model techniques showed a good agreement in terms of polymer properties such as molecular weights and tacticity distribution. Furthermore, the Monte Carlo simulation technique allowed us to have the full molecular weight and tacticity distributions. As a result, the 13C NMR analytical technique was simulated and predicted.

Heterogeneous Ziegler-Natta catalysts are responsible for most of the industrial production of polyethylene and polypropylene. A unique feature of these catalysts is the presence of more than one active site type, leading to the production of polyolefins with broad distributions of molecular weight (MWD), chemical composition (CCD) and stereoregularity. These distributions influence strongly the mechanical and rheological properties of polyolefins and are ultimately responsible for their performance and final applications. The inherent complexity of multiple-site-type heterogeneous Ziegler-Natta catalysts, where mass and heat transfer limitations are combined with a rather complex chemistry of site activation in the presence of internal and external donors, plus other phenomena such as comonomer rate enhancement, hydrogen effects, and poisoning, makes the fundamental study of these systems a very challenging proposition. In this research project, new mathematical models for the steady-state and dynamic simulation of propylene polymerization with Ziegler-Natta heterogeneous catalysts have been developed. Two different modeling techniques were compared (population balances/method of moments and Monte Carlo simulation) and a new mechanistic step (site transformation by electron donors) were simulated for the first time. Finally, polypropylene tacticity sequence length distributions were also simulated. The model techniques showed a good agreement in terms of polymer properties such as molecular weights and tacticity distribution. Furthermore, the Monte Carlo simulation technique allowed us to have the full molecular weight and tacticity distributions. As a result, the 13C NMR analytical technique was simulated and predicted.

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<p>This study analyses which factors has driven the allocation of Swedish aid between 1975 and 2003. The results are then compared to the official policy. The general goal of Swedish aid is to “help to raise the living standard for the poor”, but there are more factors than income status that affect allocation.</p><p>Allocation of Swedish aid is affected by a set of criteria for the choice of recipient. The details and the goals of aid have changed over time even if the core has remained the same. According to the official policy, Swedish aid should be used to take responsibility across borders, to contribute to a greater common market and a peaceful development. It has been considered important that the recipients’ needs can be matched by Sweden’s capacity and that aid is developed from the recipients’ situation. The recipients’ absorption capacity is thus an important criterion. Summarized, Swedish aid should be used to promote democracy, fight corruption and contribute to more equal societies.</p><p>In this study we do not find any significant relation between the official policy and actual allocation. A Generalized Least Square regression with Random Effects points out only two significant variables, the recipients’ size of trade (openness) and their former (British) colonial status.</p><p>Instead of rewarding open economies, Swedish aid has been allocated to more closed economies which tend to be more corrupt. Although the majority of the recipient countries are former colonies, we find that former British colonies are favoured. This allocation is believed to be a result of the historical development of aid and practical circumstances such as language etc...</p> / <p>Denna studie analyserar vilka faktorer som har drivit Svenskt bistånd mellan 1975 och 2003. Resultaten jämförs sedan med officiell policy. Det allmänna målet med Svensk bistånd enligt officiell policy är att ”hjälpa till att höja levnadsstandarden för de fattiga”, men det finns fler faktorer än inkomstnivå som påverkar allokeringen.</p><p>Allokering av svenskt bistånd påverkas av bestämda "länderkriteria". Detaljerna och biståndets mål har förändrats över tiden även om kärnan har varit densamma. Enligt officiell policy så ska svenskt bistånd användas för att ta ansvar som sträcker sig över gränserna, för att bidra till en större gemensam marknad samt en fredlig utveckling. Det har ansetts vara viktigt att mottagarnas behov kan mötas av Sveriges kapacitet och att biståndet är sammansatt utifrån mottagarnas situation. Mottagarnas absorptionskapacitet är således det ett viktigt kriterium. Sammanfattningsvis ska svenskt bistånd främja demokrati, kämpa mot korruption och bidra till att samhällen blir mer jämställda.</p><p>I denna studie finner vi inget signifikant samband mellan den officiella policyn och faktisk allokering. En ”Generalized Least Square Random Effects” regression påvisar blott två signifikanta variabler; mottagarnas handelsvidd (öppenhet) och deras före detta koloniala (Brittiska) status.</p><p>Istället för att belöna öppna ekonomier har svensk bistånd allokerats till mer stängda ekonomier som tenderar att vara mer korrupta. Trots att majoriteten av mottagarländerna är före detta kolonier är de Brittiska kolonierna favoriserade. Denna allokering tros vara ett resultat av biståndets historiska utveckling och praktiska omständigheter, så som språk etc…</p>

Non-covalent interactions are of great interest to chemists and biologists who study the molecular structure and function of biological systems, as well as those who seek to control, undo, or improve upon the efficiency of these systems with man-made chemical tools. The Iverson group has specifically applied noncovalent aromatic donor-acceptor interactions to biotic and abiotic aqueous systems through the use of the electron-rich 1,5-dialkoxynaphthalene (DAN) and electron-deficient 1,4,5,8-naphthalenetetracarboxylic diimide (NDI) moieties. Chapter 1 introduces and reviews the current state of self-assembly research, especially work conducted in aqueous media. Chapter 2 delineates the design and synthesis of a molecule that can self-assemble and form disulfide bonds, with the goal of creating higher-order structure. Chapter 3 comprises the design and synthesis of a series of pendant-NDI bisintercalators of DNA that are distinct from the backbone-incorporated intercalators previously employed in our laboratory. Chapter 4 contextualizes the term of art “pi-stacking,” reviewing the current state of knowledge of specific contributions to this effect and commenting on the putative uniqueness of the interaction. Theoretical and experimental work in the field is summarized. The work discussed in this dissertation serves to expand the scope of programmability of our DNA intercalators, to probe the higher-order assembly behavior of our donor-acceptor pair, and to clarify the term “pi-stacking,” lately overused, that imperfectly describes the interaction that gives both these systems their compelling binding properties. / text

published_or_final_version / Surgery / Doctoral / Doctor of Philosophy

Not available / text

Aromatic donor-acceptor interactions have been utilized by the Iverson group in the development of abiotic molecules, called aedamers, that achieve new folding motifs, intermolecular association in heteroduplexes, and new material properties. These molecules exploit the interaction between the electron-rich 1,5-dialkoxynapthalene (DAN) and electron-deficient 1,4,5,8-naphthalenetetracarboxylic diimide (NDI) units in a face-centered stacking geometry in aqueous solution. This dissertation describes the use of DAN-NDI interactions in the realm of peptides and proteins to expand the scope for applications of this interaction. This work specifically focuses on three areas of aromatic donor-acceptor interactions: achieving protein behavior with abiotic molecules, introducing the interaction into natural peptides, and utilizing the interaction in the intermolecular association of an abiotic molecule and a natural peptide. Chapter 2 refines the model of aggregation of an amphiphilic aedamer, which forms a hydrogel upon heating. The aedamer behaves similarly to proteins called amlyoids, which form fibrils and plaques in vivo which have been implicated in a variety of diseases, including Alzheimer's. Chapter 3 describes the synthesis of [alpha]-amino acids with DAN- and NDI-containing side chains. These amino acids can be used in a peptide model of [beta]-hairpin secondary structure. The model system can determine whether aromatic donor-acceptor interactions are useful in stabilizing peptide and protein structure. Chapter 4 describes the study of the Anchored Periplasmic Expression System (APEx) for use in screening random peptide libraries. A random peptide library is used to determine the sequence of a natural peptide, potentially containing electron-rich aromatic residues, which could bind an NDI oligomer with high affinity for use as a protein expression tag. Chapter 5 describes work toward the use of cyclic NDI bisintercalators for binding both the major and minor grooves of a specific sequence of DNA simultaneously, in addition to the use of cyclic NDI and DAN molecules for the further study of NDI-DAN interactions in abiotic intermolecular assembiles. Overall, this work has advanced the application of aromatic donor-acceptor interactions in peptides and should serve as a foundation for the future study of this interaction in protein folding and behavior in biological systems. / text

Idag väntar många patienter på transplantation av ett eller flera organ. Med nuvarande lagstiftning identifieras inte alla potentiella organdonatorer och därför kan inte dessa organ tas tillvara. Regeringen har därför tillsatt en utredning om det kan bli aktuellt med organdonation efter hjärtdöd. Detta uttrycks internationellt som Donation after Cardiac Death (DCD). Denna studiens syfte var att beskriva intensivvårdssjuksköterskors uppfattningar, tankar och känslor, samt förbereddhet kring begreppet donation efter hjärtdöd. Sju intervjuer av intensivvårdssjuksköterskor på två sjukhus i västra Sverige genomfördes och data analyserades med kvalitativ innehållsanalys. Resultatet presenteras som fyra kategorier: Upplevda farhågor och potentiella konsekvenser av DCD, Mötet med anhöriga, Tankar och känslor kring organisatoriska svårigheter och Tankar och känslor kring etiska dilemman. Slutsatser var att de intervjuade intensivvårdssjuksköterskorna ställde sig positiva till DCD och tidigare forskning visar att det kan vara en källa till ökning av organtillgång förutsatt att det är organisatoriskt genomförbart. / Today there are many patients on the waiting list to receive one or more organ transplants. With the current Swedish legislation not all potential organ donors are identified and therefore these organs are omitted as potential transplants. The government is in the process of investigating the possibility to implement organ donation after cardiac death, i.e. DCD. The aim of the study was to describe ICU nurses’ understanding, thoughts and emotions, as well as their preparations regards to DCD. Seven ICU nurses at two hospitals in western Sweden were interviewed and data were processed through qualitative content analysis. The results are presented as four categories: Perceived fears and potential consequences regarding DCD, the meeting with relatives, Thoughts and emotions regarding organizational difficulties and Thoughts and emotions regarding ethical dilemmas. Conclusions derived from the findings in the interviews with ICU nurses were a fully positive perception of DCD and that DCD could mean an increase in the amount of available organ donors given that legalisation and organisation processes are clear and possible to carry out.

The dissertation focuses on the recent discovery in supramolecular chemistry of novel macrocyclic compounds with NH and CH donor groups. Chapter 1 provides a brief overview of the anions under study, supramolecular chemistry, the relevant other anion receptors, as well as previous findings involving the use of CH donor groups as functional building blocks. Chapter 2, as the major focus of this dissertation, describes a pyrrolyl-based triazolophane, incorporating CH and NH donor groups, which acts as a receptor for the pyrophosphate anion in chloroform solution. It shows selectivity for this trianion, followed by HSO₄− > H₂PO₄− > Cl− > Br− (all as the corresponding tetrabutylammonium salts), with NH−anion interactions being more important than CH−anion interactions. In the solid state, the receptor binds the pyrophosphate anion in a clip-like slot via NH and CH hydrogen bonds. Chapter 3 describes a pyrrole–based triazolium–phane which has been prepared through “click” chemistry in moderate yield. It displays a high selectivity for tetrahedral oxyanions relative to various test monoanions and trigonal planar anions in mixed polar organic–aqueous solvent media. It was also found that the binding affinity and selectivity of the macrocycle to the anions are solvent dependent. Several crystal structures were solved. They confirm that the cationic macrocycle ring binds pyrophosphate and phosphate anions in the solid state. Finally, chapter 4 describes a novel 1,3,4-substituted 1,2,3-triazolium salt found to function as an effective precursor for the synthesis of structurally characterized cationic silver(I) and ruthenium(II) carbene complexes of overall 1:2 ligand-to-metal stoichiometry. The Ag(I) complex crystallized in the form of an eight silver atom containing cluster, whereas the Ru(II) complex proved to be a discrete species and was found to be capable of initiating the ring-opening metathesis polymerization of norbornene upon activation with (trimethylsilyl)diazomethane. / text