34 resultados para III COMPLEXES
em Helda - Digital Repository of University of Helsinki
Resumo:
The dissertation analyses the political culture of Sweden during the reign of King Gustav III (1771-1792). This period commonly referred to as the Gustavian era followed the so-called Age of Liberty ending half a century of strong parliamentary rule in Sweden. The question at the heart of this study engages with the practice of monarchical rule under Gustav III, its ideological origins and power-political objectives as well as its symbolic expression. The study thereby addresses the very nature of kingship. In concrete terms, why did Gustav III, his court, and his civil service vigorously pursue projects that contemporaneous political opponents and, in particular, subsequent historiography have variously pictured as irrelevant, superficial, or as products of pure vanity? The answer, the study argues, is to be found in patterns of political practice as developed and exercised by Gustav III and his administration, which formed a significant part of the political culture of Gustavian Sweden. The dissertation is divided into three parts. The first traces the use and development of royal graces chivalric orders, medals, titles, privileges, and other gifts issued by the king. The practice of royal reward is illustrated through two case studies: the 1772 coup d état that established Gustav III s rule, and the birth and baptism of the crown prince, Gustav Adolf, in 1778. The second part deals with the establishment of the Court of Appeal in Vasa in 1776. The formation of the Appeals Court was accompanied by a host of ceremonial, rhetorical, emblematic, and architectural features solidifying its importance as one of Gustav III s most symbolic administrative reform projects and hence portraying the king as an enlightened monarch par excellence. The third and final part of the thesis engages with war as a cultural phenomenon and focuses on the Russo-Swedish War of 1788-1790. In this study, the war against Russia is primarily seen as an arena for the king and other players to stage, create and re-create as well as articulate themselves through scenes and roles adhering to a particular cultural idiom. Its codes and symbolic forms, then, were communicated by means of theatre, literature, art, history, and classical mythology. The dissertation makes use of a host of sources: protocols, speeches, letters, diaries, newspapers, poetry, art, medals, architecture, inscriptions and registers. Traditional political source material and literary and art sources are studied as totalities, not as separate entities. Also it is argued that political and non-fictional sources cannot be understood properly without acknowledging the context of genre, literary conventions, and artistic modes. The study critically views the futile, but nonetheless almost habitual juxtaposition of the reality of images, ideas, and metaphors, and the reality of supposedly factual historical events. Significantly, the thesis presumes the symbolic dimension to be a constitutive element of reality, not its cooked up misrepresentation. This presumption is reflected in a discussion of the concept of role , which should not be anachronistically understood as roles in which the king cast himself at different times and in different situations. Neither Gustav III nor other European sovereigns of this period played the roles as rulers or majesties. Rather, they were monarchs both in their own eyes and in the eyes of their contemporaries as well as in all relations and contexts. Key words: Eighteenth-Century, Gustav III, Cultural History, Monarchs, Royal Graces, the Vasa Court of Appeal, the Russo-Swedish War 1788–1790.
Resumo:
Regardless of the existence of antibiotics, infectious diseases are the leading causes of death in the world. Staphylococci cause many infections of varying severity, although they can also exist peacefully in many parts of the human body. Most often Staphylococcus aureus colonises the nose, and that colonisation is considered to be a risk factor for spread of this bacterium. S. aureus is considered to be the most important Staphylococcus species. It poses a challenge to the field of medicine, and one of the most problematic aspects is the drastic increase of the methicillin-resistant S. aureus (MRSA) strains in hospitals and community world-wide, including Finland. In addition, most of the clinical coagulase-negative staphylococcus (CNS) isolates express resistance to methicillin. Methicillin-resistance in S. aureus is caused by the mecA gene that encodes an extra penicillin-binding protein (PBP) 2a. The mecA gene is found in a mobile genomic island called staphylococcal chromosome cassette mec (SCCmec). The SCCmec consists of the mec gene and cassette chromosome recombinase (ccr)gene complexes. The areas of the SCCmec element outside the ccr and mec complex are known as the junkyard J regions. So far, eight types of SCCmec(SCCmec I- SCCmec VIII) and a number of variants have been described. The SCCmec island is an acquired element in S. aureus. Lately, it appears that CNS might be the storage place of the SCCmec that aid the S. aureus by providing it with the resistant elements. The SCCmec is known to exist only in the staphylococci. The aim of the present study was to investigate the horizontal transfer of SCCmec between the S. aureus and CNS. One specific aim was to study whether or not some methicillin-sensitive S. aureus (MSSA) strains are more inclined to receive the SCCmec than others. This was done by comparing the genetic background of clinical MSSA isolates in the health care facilities of the Helsinki and Uusimaa Hospital District in 2001 to the representatives of the epidemic MRSA (EMRSA) genotypes, which have been encountered in Finland during 1992-2004. Majority of the clinical MSSA strains were related to the EMRSA strains. This finding suggests that horizontal transfer of SCCmec from unknown donor(s) to several MSSA background genotypes has occurred in Finland. The molecular characteristics of representative clinical methicillin-resistant S. epidermidis (MRSE) isolates recovered in Finnish hospitals between 1990 and 1998 were also studied, examining their genetic relation to each other and to the internationally recognised MRSE clones as well, so as to ascertain the common traits between the SCCmec elements in MRSE and MRSA. The clinical MRSE strains were genetically related to each other; eleven PFGE types were associated with sequence type ST2 that has been identified world-wide. A single MRSE strain may possess two SCCmec types III and IV, which were recognised among the MRSA strains. Moreover, six months after the onset of an outbreak of MRSA possessing a SCCmec type V in a long-term care facility in Northern Finland (LTCF) in 2003, the SCCmec element of nasally carried methicillin-resistant staphylococci was studied. Among the residents of a LTCF, nasal carriage of MR-CNS was common with extreme diversity of SCCmec types. MRSE was the most prevalent CNS species. Horizontal transfer of SCCmec elements is speculated to be based on the sharing of SCCmec type V between MRSA and MRSE in the same person. Additionally, the SCCmec element of the clinical human S. sciuri isolates was studied. Some of the SCCmec regions were present in S. sciuri and the pls gene was common in it. This finding supports the hypothesis of genetic exchange happening between staphylococcal species. Evaluation of the epidemiology of methicillin-resistant staphylococcal colonisation is necessary in order to understand the apparent emergence of these strains and to develop appropriate control strategies. SCCmec typing is essential for understanding the emergence of MRSA strains from CNS, considering that the MR-CNS may represent the gene pool for the continuous creation of new SCCmec types from which MRSA might originate.
Resumo:
Radioactive particles from three locations were investigated for elemental composition, oxidation states of matrix elements, and origin. Instrumental techniques applied to the task were scanning electron microscopy, X-ray and gamma-ray spectrometry, secondary ion mass spectrometry, and synchrotron radiation based microanalytical techniques comprising X-ray fluorescence spectrometry, X-ray fluorescence tomography, and X-ray absorption near-edge structure spectroscopy. Uranium-containing low activity particles collected from Irish Sea sediments were characterized in terms of composition and distribution of matrix elements and the oxidation states of uranium. Indications of the origin were obtained from the intensity ratios and the presence of thorium, uranium, and plutonium. Uranium in the particles was found to exist mostly as U(IV). Studies on plutonium particles from Runit Island (Marshall Islands) soil indicated that the samples were weapon fuel fragments originating from two separate detonations: a safety test and a low-yield test. The plutonium in the particles was found to be of similar age. The distribution and oxidation states of uranium and plutonium in the matrix of weapon fuel particles from Thule (Greenland) sediments were investigated. The variations in intensity ratios observed with different techniques indicated more than one origin. Uranium in particle matrixes was mostly U(IV), but plutonium existed in some particles mainly as Pu(IV), and in others mainly as oxidized Pu(VI). The results demonstrated that the various techniques were effectively applied in the characterization of environmental radioactive particles. An on-line method was developed for separating americium from environmental samples. The procedure utilizes extraction chromatography to separate americium from light lanthanides, and cation exchange to concentrate americium before the final separation in an ion chromatography column. The separated radiochemically pure americium fraction is measured by alpha spectrometry. The method was tested with certified sediment and soil samples and found to be applicable for the analysis of environmental samples containing a wide range of Am-241 activity. Proceeding from the on-line method developed for americium, a method was also developed for separating plutonium and americium. Plutonium is reduced to Pu(III), and separated together with Am(III) throughout the procedure. Pu(III) and Am(III) are eluted from the ion chromatography column as anionic dipicolinate and oxalate complexes, respectively, and measured by alpha spectrometry.
Resumo:
The literature part of the thesis mainly reviews the results of the use of titanium catalysts for ethene and caprolactone polymerisation. The behaviour of titanium catalysts bearing phenoxy-imino ligands has been the focus of more detailed investigations in ethene polymerisation. Reasons for the production of multimodal polyethene for a range of catalysts are also given. The experimental part of the thesis is divided into two sections based on the monomers used in the polymerisations: Part A (ethene) and part B (caprolactone). Part A: Titanium(IV) complexes bearing phenoxy-imino ligands are known to possess high ethene polymerisation activities after MAO activation. Depending on the ligand, the activities of the catalysts in polymerisation can vary between 1 and 44000 kgPE/(mol*cat*h*bar). Depending on the polymerisation temperature and the electronic and steric properties of the catalyst ligands, low to high molar mass values and uni- and multimodal polydispersity values can been observed. In order to discover the reasons for these differences, 22 titanium(IV) complexes containing differently substituted phenoxy-imino derivatives as di- and tetradentate ligands were synthesised with high yields and used as homogeneous catalysts in ethene polymerisations. Computational methods were used to predict the geometry of the synthesised complexes and their configuration after activation. Based on the results obtained, the geometry of the catalyst together with the ligand substituents seem to play a major role in defining the catalytic activity. Novel titanium(IV) complexes bearing malonate ligands were also synthesised. Malonates are considered to be suitable ligand pre-cursors since they can be produced by the simple reaction of any primary or secondary alcohol with malonylchloride, and thus they are easily modifiable. After treatment with MAO these complexes had polymerisation activities between 10 and 50 kgPE/(mol*cat*h*bar) and surprisingly low polydispersity values when compared with similar types of catalysts bearing the O?O chelate ligand. Part B: One of the synthesis routes in the preparation of the above mentioned phenoxy-imino titanium dichloride complexes involved the use of Ti(NMe2)4 with a range of salicylaldimine type compounds. On reaction, these two compounds formed an intermediate product selectively and quantitatively which was active in the ring-opening polymerisation of caprolactone. Several mono-anionic alcoholates were also combined with Ti(NMe2)4 in different molar ratios and used as catalysts. Full conversion of the monomer was achieved within 15 minutes with catalysts having a co-ordination number of 4 while after 22 hours full conversion was achieved with catalysts having a co-ordination number of 6.
Resumo:
The commodity plastics that are used in our everyday lives are based on polyolefin resins and they find wide variety of applications in several areas. Most of the production is carried out in catalyzed low pressure processes. As a consequence polymerization of ethene and α-olefins has been one of the focus areas for catalyst research both in industry and academia. Enormous amount of effort have been dedicated to fine tune the processes and to obtain better control of the polymerization and to produce tailored polymer structures The literature review of the thesis concentrates on the use of Group IV metal complexes as catalysts for polymerization of ethene and branched α-olefins. More precisely the review is focused on the use of complexes bearing [O,O] and [O,N] type ligands which have gained considerable interest. Effects of the ligand framework as well as mechanical and fluxional behaviour of the complexes are discussed. The experimental part consists mainly of development of new Group IV metal complexes bearing [O,O] and [O,N] ligands and their use as catalysts precursors in ethene polymerization. Part of the experimental work deals with usage of high-throughput techniques in tailoring properties of new polymer materials which are synthesized using Group IV complexes as catalysts. It is known that the by changing the steric and electronic properties of the ligand framework it is possible to fine tune the catalyst and to gain control over the polymerization reaction. This is why in this thesis the complex structures were designed so that the ligand frameworks could be fairly easily modified. All together 14 complexes were synthesised and used as catalysts in ethene polymerizations. It was found that the ligand framework did have an impact within the studied catalyst families. The activities of the catalysts were affected by the changes in complex structure and also effects on the produced polymers were observed: molecular weights and molecular weight distributions were depended on the used catalyst structure. Some catalysts also produced bi- or multi-modal polymers. During last decade high-throughput techniques developed in pharmaceutical industries have been adopted into polyolefin research in order to speed-up and optimize the catalyst candidates. These methods can now be regarded as established method suitable for both academia and industry alike. These high-throughput techniques were used in tailoring poly(4-methyl-1-pentene) polymers which were synthesized using Group IV metal complexes as catalysts. This work done in this thesis represents the first successful example where the high-throughput synthesis techniques are combined with high-throughput mechanical testing techniques to speed-up the discovery process for new polymer materials.
Resumo:
This thesis studies the intermolecular interactions in (i) boron-nitrogen based systems for hydrogen splitting and storage, (ii) endohedral complexes, A@C60, and (iii) aurophilic dimers. We first present an introduction of intermolecular interactions. The theoretical background is then described. The research results are summarized in the following sections. In the boron-nitrogen systems, the electrostatic interaction is found to be the leading contribution, as 'Coulomb Pays for Heitler and London' (CHL). For the endohedral complex, the intermolecular interaction is formulated by a one-center expansion of the Coulomb operator 1/rab. For the aurophilic attraction between two C2v monomers, a London-type formula was derived by fully accounting for the anisotropy and point-group symmetry of the monomers.
Resumo:
Polyethene, polyacrylates and polymethyl acrylates are versatile materials that find wide variety of applications in several areas. Therefore, polymerization of ethene, acrylates and methacrylates has achieved a lot attention during past years. Numbers of metal catalysts have been introduced in order to control the polymerization and to produce tailored polymer structures. Herein an overview on the possible polymerization pathways for ethene, acrylates and methacrylates is presented. In this thesis iron(II) and cobalt(II) complexes bearing tri- and tetradentate nitrogen ligands were synthesized and studied in the polymerization of tertbutyl acrylate (tBA) and methyl methacrylate (MMA). Complexes are activated with methylaluminoxane (MAO) before they form active combinations for polymerization reactions. The effect of reaction conditions, i.e. monomer concentration, reaction time, temperature, MAO to metal ratio, on activity and polymer properties were investigated. The described polymerization system enables mild reaction conditions, the possibility to tailor molar mass of the produced polymers and provides good control over the polymerization. Moreover, the polymerization of MMA in the presence of iron(II) complex with tetradentate nitrogen ligands under conditions of atom transfer radical polymerization (ATRP) was studied. Several manganese(II) complexes were studied in the ethene polymerization with combinatorial methods and new active catalysts were found. These complexes were also studied in acrylate and methacrylate polymerizations after MAO activation and converted into the corresponding alkyl (methyl or benzyl) derivatives. Combinatorial methods were introduced to discover aluminum alkyl complexes for the polymerization of acrylates and methacrylates. Various combinations of aluminum alkyls and ligands, including phosphines, salicylaldimines and nitrogen donor ligands, were prepared in situ and utilized to initiate the polymerization of tBA. Phosphine ligands were found to be the most active and the polymerization MMA was studied with these active combinations. In addition, a plausible polymerization mechanism for MMA based on ESI-MS, 1H and 13C NMR is proposed.
Resumo:
Schiff bases and their transition metal complexes are of significant current interest even though they have been prepared for decades. They have been used in various applications such as catalysis, corrosion protection, and molecular sensors. In this study, N-aryl Schiff base ketimine ligands as well as numerous new, differently substituted salen and salophen-type ligands and their cobalt(II), copper(II), iron(II), manganese(II), and nickel(II) complexes were synthesised. New solid state structures of the above compounds and the dioxygen coordination properties of cobalt(II) complexes and catalytic properties of three synthesised binuclear complexes were examined. The prepared complexes were applied in the formation of self-assembled layers on a polycrystalline gold surface and liquid-graphite interface. The effect of metal ion and ligand structure on the as-formed patterns was studied. When studying gold surfaces, a unique thiol-assisted dissolution of elemental gold was observed and a new thin gold foil preparation method was introduced. In the summary, synthesis, structures, and properties of Schiff base ligands and their transition metal complexes are described in detail and the applications of these reviewed. Assemblies of other complexes on a liquid-graphite interface and on a gold surface are also presented, and the surface characterisation methods and surfaces employed are described.
Studies on metal complex formation of environmentally friendly aminopolycarboxylate chelating agents
Resumo:
Aminopolykarboksyylaatteja, kuten etyleenidiamiinitetraetikkahappoa (EDTA), on käytetty useiden vuosikymmenien ajan erinomaisen metalli-ionien sitomiskyvyn vuoksi kelatointiaineena lukuisissa sovelluksissa sekä analytiikassa että monilla teollisisuuden aloilla. Näiden yhdisteiden biohajoamattomuus on kuitenkin herättänyt huolta viime aikoina, sillä niiden on havaittu olevan hyvin pysyviä luonnossa. Tämä työ on osa laajempaa tutkimushanketta, jossa on tavoitteena löytää korvaavia kelatointiaineita EDTA:lle. Tutkimuksen aiheena on kuuden kelatointiaineen metalli-ionien sitomiskyvyn kartoitus. EDTA:a paremmin luonnossa hajoavina nämä ovat ympäristöystävällisiä ehdokkaita korvaaviksi kelatointiaineiksi useisiin sovelluksiin. Työssä tutkittiin niiden kompleksinmuodostusta useiden metalli-ionien kanssa potentiometrisella titrauksella. Metalli-ionivalikoima vaihteli hieman kelatointiaineesta riippuen sisältäen magnesium-, kalsium-, mangaani-, rauta-, kupari-, sinkki-, kadmium-, elohopea-, lyijy- ja lantaani-ionit. Tutkittavat metallit oli valittu tähtäimessä olevien sovellusten, synteesissä ilmenneiden ongelmien tai ympäristönäkökohtien perusteella. Tulokset osoittavat näiden yhdisteiden metallinsitomiskyvyn olevan jonkin verran heikompi kuin EDTA:lla, mutta kuitenkin riittävän useisiin sovelluksiin kuten sellunvalkaisuprosessiin. Myrkyllisten raskasmetallien, kadmiumin, elohopen ja lyijyn kohdalla EDTA:a heikompi sitoutuminen on eduksikin, koska se yhdistettynä parempaan biohajoavuuteen saattaa alentaa tutkittujen yhdisteiden kykyä mobilisoida kyseisiä metalleja sedimenteistä. Useimmilla tutkituista yhdisteistä on ympäristönäkökulmasta etuna myös EDTA:a pienempi typpipitoisuus.