Synthesis, characterization and chemical sensor application of conducting polymers

Polymeric materials that conduct electricity are highly interesting for fundamental studies and beneficial for modern applications in e.g. solar cells, organic field effect transistors (OFETs) as well as in chemical and bio‐sensing. Therefore, it is important to characterize this class of materials with a wide variety of methods. This work summarizes the use of electrochemistry also in combination with spectroscopic methods in synthesis and characterization of electrically conducting polymers and other π‐conjugated systems. The materials studied in this work are intended for organic electronic devices and chemical sensors. Additionally, an important part of the presented work, concerns rational approaches to the development of water‐based inks containing conducting particles. Electrochemical synthesis and electroactivity of conducting polymers can be greatly enhanced in room temperature ionic liquids (RTILs) in comparison to conventional electrolytes. Therefore, poly(para‐phyenylene) (PPP) was electrochemically synthesized in the two representative RTILs: bmimPF6 and bmiTf2N (imidazolium and pyrrolidinium‐based salts, respectively). It was found that the electrochemical synthesis of PPP was significantly enhanced in bmimPF6. Additionally, the results from doping studies of PPP films indicate improved electroactivity in bmimPF6 during oxidation (p‐doping) and in bmiTf2N in the case of reduction (n‐doping). These findings were supported by in situ infrared spectroscopy studies. Conducting poly(benzimidazobenzophenanthroline) (BBL) is a material which can provide relatively high field‐effect mobility of charge carriers in OFET devices. The main disadvantage of this n‐type semiconductor is its limited processability. Therefore in this work BBL was functionalized with poly(ethylene oxide) PEO, varying the length of side chains enabling water dispersions of the studied polymer. It was found that functionalization did not distract the electrochemical activity of the BBL backbone while the processability was improved significantly in comparison to conventional BBL. Another objective was to study highly processable poly(3,4‐ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) water‐based inks for controlled patterning scaled‐down to nearly a nanodomain with the intention to fabricate various chemical sensors. Developed PEDOT:PSS inks greatly improved printing of nanoarrays and with further modification with quaternary ammonium cations enabled fabrication of PEDOT:PSS‐based chemical sensors for lead (II) ions with enhanced adhesion and stability in aqueous environments. This opens new possibilities for development of PEDOT:PSS films that can be used in bio‐related applications. Polycyclic aromatic hydrocarbons (PAHs) are a broad group of π‐conjugated materials consisting of aromatic rings in the range from naphthalene to even hundred rings in one molecule. The research on this type of materials is intriguing, due to their interesting optical properties and resemblance of graphene. The objective was to use electrochemical synthesis to yield relatively large PAHs and fabricate electroactive films that could be used as template material in chemical sensors. Spectroscopic, electrochemical and electrical investigations evidence formation of highly stable films with fast redox response, consisting of molecules with 40 to 60 carbon atoms. Additionally, this approach in synthesis, starting from relatively small PAH molecules was successfully used in chemical sensor for lead (II).

Phenolics of the Inner Bark of Silver Birch: Characterization and Intraspecific Variation

This thesis describes work related to the in-depth characterization of the phenolic compounds of silver birch (Betula pendula) inner bark. Phenolic compounds are the most ubiquitous class of plant secondary compounds. The unifying feature of this structurally diverse group is an aromatic ring containing at least one hydroxyl group. Due to the structural diversity, phenolics have various roles in the plant defense against biotic and abiotic stresses. In addition, they can confer several health-promoting properties to humans. Furthermore, the structural diversity of this class of compounds causes challenges for their analysis. The study species in the present work, silver birch, is economically the most important hard wood species in northern Europe. Its inner bark contains a high level of phenolic compounds and it has shown one of the strongest antioxidant activities among 92 Finnish plant materials. The literature review surveys the diversity and organ specific distribution of phenolic compounds in silver birch as well as the proposed ecological functions of phenolic compounds in nature. In addition, the basis for the characterization of phenolics by mass spectrometry (MS), nuclear magnetic resonance spectroscopy (NMR), and circular dichroism spectroscopy (CD) are reviewed. The objective of the experimental work was to extract, purify, characterize, and quantify the inner bark phenolic compounds. Overall 36 compounds were characterized by MS and ultraviolet spectroscopy (UV). 24 compounds were isolated and their structures confirmed by NMR and CD spectroscopy. Five novel natural compounds were identified. Special emphasis was placed on the establishment of a method for the characterization of proanthocyanidins (PAs). Hydrophilic interaction liquid chromatography (HILIC) was utilized because of its high resolution power and predictable elution order of oligomeric and polymeric PAs according to an increasing degree of polymerization. The combination of HILIC and high-resolution MS detection allowed the identification of procyanidin (PC) polymers up to the degree of polymerization of 22. In addition, a series of oligomeric and polymeric PC monoxylosides were observed for the first time in nature. Season and genotype influenced the quantities of the main inner bark phenolics, yet qualitative differences were not observed. However, manual wounding of the inner bark induced the production of ellagitannins (ETs) in the wounded tissues, i.e. callus. Since ETs were not detected in the intact inner bark, this finding may reflect the capacity of silver birch to exploit ellagitannins in its defense.

Virulence properties of Aggregatibacter actinomycetemcomitans biofilm and characterisation of its putative cytokine exploitation

Biofilms are surface-attached multispecies microbial communities that are embedded by their self-produced extracellular polymeric substances. This lifestyle enhances the survival of the bacteria and plays a major role in many chronic bacterial infections. For instance, periodontitis is initiated by multispecies biofilms. The phases of active periodontal tissue destruction and notably increased levels of proinflammatory mediators, such as the key inflammatory mediator interleukin (IL)-1beta, are typical of the disease. The opportunistic periodontal pathogen Aggregatibacter actinomycetemcomitans is usually abundant at sites of aggressive periodontitis. Despite potent host immune system responses to subgingival invaders, A. actinomycetemcomitans is able to resist clearance attempts. Moreover, some strains of A. actinomycetemcomitans can generate genetic diversity through natural transformation, which may improve the species’ adjustment tothe subgingival environment in the long term. Some biofilm forming species are known to bind and sense human cytokines. As a response to cytokines, bacteria may increase biofilm formation and alter their expression of virulence genes. Specific outer membrane receptors for interferon-γ or IL-1β have been characterised in two Gram-negative pathogens. Because little is known about periodontal pathogens’ ability to sense cytokines, we used A. actinomycetemcomitans as a model organism to investigate how the species responds to IL-1beta. The main aims of this thesis were to explore cytokine binding on single-species A. actinomycetemcomitans biofilms and to determine the effects of cytokines on the biofilm formation and metabolic activity of the species. Additionally, the cytokine’s putative internalisation and interaction with A. actinomycetemcomitans proteins were studied. The possible impact of biofilm IL-1beta sequestering on the proliferation and apoptosis of gingival keratinocyte cells was evaluated in an organotypic mucosa co-culture model. Finally, the role of the extramembranous domain of the outer membrane protein HofQ (emHofQ) in DNA binding linked to DNA uptake in A. actinomycetemcomitans was examined. Our main finding revealed that viable A. actinomycetemcomitans biofilms can bind and take up the IL-1β produced by gingival cells. At the sites of pathogen-host interaction, the proliferation and apoptosis of gingival keratinocytes decreased slightly. Notably, the exposure of biofilms to IL-1beta caused their metabolic activity to drop, which may be linked to the observed interaction of IL-1beta with the conserved intracellular proteins DNA binding protein HU and the trimeric form of ATP synthase subunit beta. A Pasteurellaceaespecific lipoprotein, which had no previously determined function, was characterized as an IL-1beta interacting membrane protein that was expressed in the biofilm cultures of all tested A. actinomycetemcomitans strains. The use of a subcellular localisation tool combined with experimental analyses suggested that the identified lipoprotein, bacterial interleukin receptor I (BilRI), may be associated with the outer membrane with a portion of the protein oriented towards the external milieu. The results of the emHofQ study indicated that emHofQ has both the structural and functional capability to bind DNA. This result implies that emHofQ plays a role in DNA assimilation. The results from the current study also demonstrate that the Gram-negative oral species appears to sense the central proinflammatory mediator IL-1beta.

Suomen satamissa käsiteltävät pakatut vaaralliset aineet ja esimerkkejä niiden vaaraominaisuuksista

Tämä raportti on tehty osana Kymenlaakson ammattikorkeakoulun hallinnoiman NELIn (North European Logistics Institute) esiselvitystä vaarallisten aineiden tunnistamisesta konttiliikenteessä. Tässä Turun yliopiston merenkulkualan koulutus- ja tutkimuskeskuksen Kotkassa toimivan Merenkulun logistiikan tutkimus -yksikön tekemässä selvityk-sessä on tutkittu kansallista satamaliikenteen PortNet-järjestelmää hyödyntäen, mitä pakattuina kuljetettavia vaarallisia aineita ja kuinka suuria määriä Suomen satamissa käsitellään. PortNet-analyysin tulosten pohjalta tutkimuksessa on selvitetty Suomen satamissa eniten käsiteltyjen, pakattuina kuljetettavien vaarallisten aineiden vaaraominaisuuksia sekä ihmisten että ympäristön kannalta. Tutkimuksessa tehdyn PortNet-analyysin perusteella pakattuja vaarallisia aineita käsiteltiin 16:ssa Suomen satamassa vuonna 2012. Käsiteltyjen aineiden kokonaismäärä oli noin 820 000 tonnia, josta viennin osuus oli 53 % ja tuonnin 47 %. Eniten kuljetettuja IMDG-luokkia olivat luokan 3 palavat nesteet (31 %:n osuus), luokan 9 muut vaaralliset aineet ja esineet (25 %) sekä luokan 8 syövyttävät aineet (23 %). Muiden luokkien osuus oli alle 10 %. Suomen satamissa käsiteltiin vuonna 2012 yhteensä noin 1 020 eri-laista, pakattua vaarallista ainetta. Yli 10 000 tonnia käsiteltyjä aineita oli yhteensä 16, 1 000–10 000 tonnia käsiteltyjä aineita 84, 100–1 000 tonnia käsiteltyjä aineita 148 ja alle 100 tonnia käsiteltyjä aineita noin 770. Eniten käsiteltyjä aineita olivat pääasiassa erilaiset aineyhdisteet ja tarkemmin määrittelemättömät aineet, kuten ympäristölle vaarallinen aine n.o.s, maalit, polymeeripelletit, hartsiliuos, kohotetussa lämpötilassa oleva neste n.o.s. ja nikkelimetallihybridiakut. Näitä kaikkia käsiteltiin Suomen satamissa yli 20 000 tonnia vuonna 2012. Varsinaisista yksittäisistä vaarallisista aineista eniten käsiteltyjä olivat muurahaishappo, vetyperoksidin vesiliuos, natriumkloraatti, ammoniumnitraatti, fenoli ja kloorietikkahappoliuos. Näitä kaikkia käsiteltiin yli 10 000 tonnia vuonna 2012. PortNet-analyysin tulosten pohjalta valittiin kymmenen ainetta, joiden vaaraominaisuuksia sekä ihmisten että ympäristön kannalta tarkasteltiin tarkemmin. Tarkasteluun valittiin, tieteellistä harkintaa käyttäen, eniten kuljetettavia vaarallisia yksittäisiä kemikaaleja. Tarkasteluun valitut kemikaalit olivat muurahaishappo, vetyperoksidi, natrium-kloraatti, kloorietikkahappo, fenoli, akryyliamidiliuos, ksyleenit, akryylinitriili, tolueeni ja epikloorihydriini. Tutkituista kemikaaleista ympäristölle haitallisimpia ovat fenoli, kloorietikkahappo ja akryyliamidiliuos. Ihmisen kannalta kaikki 10 tutkittua kemikaalia muodostavat onnettomuustilanteessa riskin ihmisten terveydelle joko syövyttävyytensä, reaktiivisuutensa tai myrkyllisyytensä vuoksi. Osa kemikaaleista voi aiheuttaa ihmisille myös kroonisia haittoja, kuten kohonnutta syöpäriskiä tai muutoksia perimässä, joko suurina kerta-annoksina tai pieninä toistuvina pitoisuuksina. Suomen satamissa käsiteltävien pakattujen kemikaalien erilaisuus ja suuri lukumäärä tekevät niistä vaikeasti hallittavissa olevan riskitekijän. Yleisesti ottaen voidaan sanoa, että pakatuista kemikaaleista aiheutuu pienehköissä vuototilanteissa suurempi uhka ihmisen terveydelle kuin ympäristölle, kun taas irtolastikuljetuksissa tapahtuvien onnettomuuksien yhteydessä vuotaneen aineen määrä on yleensä suurempi ja näin ollen myös ympäristölle koituva uhka voi olla suuri.

Scheduling dynamic dataflow graphs with model checking

With the shift towards many-core computer architectures, dataflow programming has been proposed as one potential solution for producing software that scales to a varying number of processor cores. Programming for parallel architectures is considered difficult as the current popular programming languages are inherently sequential and introducing parallelism is typically up to the programmer. Dataflow, however, is inherently parallel, describing an application as a directed graph, where nodes represent calculations and edges represent a data dependency in form of a queue. These queues are the only allowed communication between the nodes, making the dependencies between the nodes explicit and thereby also the parallelism. Once a node have the su cient inputs available, the node can, independently of any other node, perform calculations, consume inputs, and produce outputs. Data ow models have existed for several decades and have become popular for describing signal processing applications as the graph representation is a very natural representation within this eld. Digital lters are typically described with boxes and arrows also in textbooks. Data ow is also becoming more interesting in other domains, and in principle, any application working on an information stream ts the dataflow paradigm. Such applications are, among others, network protocols, cryptography, and multimedia applications. As an example, the MPEG group standardized a dataflow language called RVC-CAL to be use within reconfigurable video coding. Describing a video coder as a data ow network instead of with conventional programming languages, makes the coder more readable as it describes how the video dataflows through the different coding tools. While dataflow provides an intuitive representation for many applications, it also introduces some new problems that need to be solved in order for data ow to be more widely used. The explicit parallelism of a dataflow program is descriptive and enables an improved utilization of available processing units, however, the independent nodes also implies that some kind of scheduling is required. The need for efficient scheduling becomes even more evident when the number of nodes is larger than the number of processing units and several nodes are running concurrently on one processor core. There exist several data ow models of computation, with different trade-offs between expressiveness and analyzability. These vary from rather restricted but statically schedulable, with minimal scheduling overhead, to dynamic where each ring requires a ring rule to evaluated. The model used in this work, namely RVC-CAL, is a very expressive language, and in the general case it requires dynamic scheduling, however, the strong encapsulation of dataflow nodes enables analysis and the scheduling overhead can be reduced by using quasi-static, or piecewise static, scheduling techniques. The scheduling problem is concerned with nding the few scheduling decisions that must be run-time, while most decisions are pre-calculated. The result is then an, as small as possible, set of static schedules that are dynamically scheduled. To identify these dynamic decisions and to find the concrete schedules, this thesis shows how quasi-static scheduling can be represented as a model checking problem. This involves identifying the relevant information to generate a minimal but complete model to be used for model checking. The model must describe everything that may affect scheduling of the application while omitting everything else in order to avoid state space explosion. This kind of simplification is necessary to make the state space analysis feasible. For the model checker to nd the actual schedules, a set of scheduling strategies are de ned which are able to produce quasi-static schedulers for a wide range of applications. The results of this work show that actor composition with quasi-static scheduling can be used to transform data ow programs to t many different computer architecture with different type and number of cores. This in turn, enables dataflow to provide a more platform independent representation as one application can be fitted to a specific processor architecture without changing the actual program representation. Instead, the program representation is in the context of design space exploration optimized by the development tools to fit the target platform. This work focuses on representing the dataflow scheduling problem as a model checking problem and is implemented as part of a compiler infrastructure. The thesis also presents experimental results as evidence of the usefulness of the approach.

Membrane development for oil contaminated water treatments

The aim of this Master’s thesis study was to develop a membrane for oil contaminated water treatments. Oily wastewaters are a big problem to environment and therefore it is important to find an efficient method for their treatment. There are several treatment methods, but one of the most promising methods is membrane filtration. In the theoretical part of this study the membrane technology and polymeric membrane preparation with phase inversion and membrane modification methods was discussed. It was also told about the most important properties of the membranes. Oily waters, their treatment methods and oily wastewater sources were discussed more specifically. In the experimental part membranes from cellulose acetate were prepared and membranes were modified with two different methods. Modification methods were surface modification and polymer mixing. The modification purpose was to make membranes more hydrophilic and increase surface charge, which can reduce fouling. Membranes were characterized by determining zeta potential, contact angle, oil retention, pure water permeability, pressure-normalized flux and fouling. It were used both synthetic and real spent oil-water emulsion in membrane filtration. Surface modification resulted membranes, which had better properties than unmodified membrane. The amount of substance used in surface modification affected a lot to membrane properties, so it would be necessary to try different amounts of substance to develop the best membrane for oil-water emulsion treatment.

Säteilysuojelu käytetyn ydinpolttoaineen kapselointi- ja loppusijoituslaitoksella

Suomen ydinenergialaki vaatii ydinenergian käytössä syntyvän ydinjätteen käsittelyn ja varastoinnin sekä loppusijoittamisen Suomeen. Fortumin ja TVO:n ydinvoimalaitoksissa syntyvä käytetty ydinpolttoaine tullaan kapseloimaan ja loppusijoittamaan Olkiluotoon rakennettavassa kapselointi- ja loppusijoituslaitoksessa. Tämän työn tavoitteena on muodostaa kokonaiskuva kapselointi- ja loppusijoituslaitoksen säteilysuojelusta aikaisemmin tehtyjen selvitysten ja suunnitelmien perusteella. Kapselointilaitoksella käytetty ydinpolttoaine suljetaan kuparikapseleihin, jotka loppusijoitetaan maan alle loppusijoituslaitoksella. Työn aluksi kuvataan loppusijoitusmenetelmä ja kapselointi- ja loppusijoituslaitoksen käyttötoiminta. Tämän jälkeen käsitellään lainsäädäntöä ja viranomaisohjeita, jotka ohjaavat ydinlaitosten säteilysuojelua. Seuraavaksi käsitellään kapselointi- ja loppusijoituslaitoksella olevia säteilylähteitä. Lisäksi työssä käsitellään kapselointi- ja loppusijoituslaitokselle suunniteltua valvonta-aluetta ja sen säteilyolosuhteiden mukaista vyöhykejakoa. Työssä saatiin tulokseksi kokonaiskuva kapselointi- ja loppusijoituslaitoksen säteilysuojelusta. Kokonaiskuvan muodostamisen lisäksi laadittiin alustavia suunnitelmia käyttötoiminnan säteilysuojelun järjestämisestä. Lisäksi laadittiin ehdotuksia valvonta-alueen tarkemmista rajoista loppusijoituslaitoksella sekä havaittiin laitosten säteilysuojeluun liittyviä ongelmia ja esitettiin ratkaisuja niihin. Ongelmaksi osoittautui muun muassa, että kapselointi- ja loppusijoituslaitoksen valvonta-alueiden luonteiden eroa ei ollut huomioitu suunnitelmissa. Lisäksi todettiin, että nykyisin ydinlaitoksilla käytössä oleva valvonta-alueen vyöhykejako ei vastaa kapselointi- ja loppusijoituslaitosten tarpeita. Näihin esitettiin ratkaisuiksi laitosten välille perustettavaa kenkärajaa ja uuden korkeamman säteilyvyöhykkeen käyttöönottoa.

Poly-DL-lactide-co-glycolide microspheres as a controlled release antigen delivery system

Successful vaccine application means maximum protection with minimal number of administrations. A rational development of vaccines involves studies of the nature of the antigen as well as of the adjuvant to be used to improve the immune responses. This has provided the impetus for studies to design the degradable devices and for different approaches to antigen delivery by different routes of administration. The development of controlled release systems based on polymeric devices that permit a sustained or pulsed release of encapsulated antigens has attracted much interest. Polymeric delivery systems consist of polymers that release their content continuously in a controlled manner over a period of time. The development of a biocompatible delivery system for parenteral administration offers several advantages in terms of immunoadjuvanticity over other compounds. It was found that, in contrast to other carriers, microspheres are more stable, thus permitting administration by the oral or parenteral route. In the present study, we describe the main characteristics and potentialities of this new immunoadjuvant for oral and parenteral administration.

Liposomes: from biophysics to the design of peptide vaccines

Liposomes (lipid-based vesicles) have been widely studied as drug delivery systems due to their relative safety, their structural versatility concerning size, composition and bilayer fluidity, and their ability to incorporate almost any molecule regardless of its structure. Liposomes are successful in inducing potent in vivo immunity to incorporated antigens and are now being employed in numerous immunization procedures. This is a brief overview of the structural, biophysical and pharmacological properties of liposomes and of the current strategies in the design of liposomes as vaccine delivery systems.

New families of highly efficient, halogen-free flame retardants for polypropylene (PP)

The driving forces for current research of flame retardants are increased fire safety in combination with flame retardant formulations that fulfill the criteria of sustainable production and products. In recent years, important questions about the environmental safety of antimony, and in particular, brominated flame retardants have been raised. As a consequence of this, the current doctoral thesis work describes efforts to develop new halogen-free flame retardants that are based on various radical generators and phosphorous compounds. The investigation was first focused on compounds that are capable of generating alkyl radicals in order to study their role on flame retardancy of polypropylene. The family of azoalkanes was selected as the cleanest and most convenient source of free alkyl radicals. Therefore, a number of symmetrical and unsymmetrical azoalkanes of the general formula R-N=N-R’ were prepared. The experimental results show that in the series of different sized azocycloalkanes the flame retardant efficacy decreased in the following order: R = R´= cyclohexyl > cyclopentyl > cyclobutyl > cyclooctanyl > cyclododecanyl. However, in the series of aliphatic azoalkanes compounds, the efficacy decreased as followed: R = R´= n-alkyl > tert-butyl > tert-octyl. The most striking difference in flame retardant efficacy was observed in thick polypropylene plaques of 1 mm, e.g. azocyclohexane (AZO) had a much better flame retardant performance than did the commercial reference FR (Flamestab® NOR116) in thick PP sections. In addition, some of the prepared azoalkane flame retardants e.g. 4’4- bis(cyclohexylazocyclohexyl) methane (BISAZO) exhibited non-burning dripping behavior. Extrusion coating experiments of flame retarded low density polyethylene (LDPE) onto a standard machine finished Kraft paper were carried out in order to investigate the potential of azoalkanes in multilayer facings. The results show that azocyclohexane (AZO) and 4’4-bis (cyclohexylazocyclohexyl) methane (BISAZO) can significantly improve the flame retardant properties of low density polyethylene coated paper already at 0.5 wt.% loadings, provided that the maximum extrusion temperature of 260 oC is not exceeded and coating weight is kept low at 13 g/m2. In addition, various triazene-based flame retardants (RN1=N2-N3R’R’’) were prepared. For example, polypropylene samples containing a very low concentration of only 0.5 wt.% of bis- 4’4’-(3’3’-dimethyltriazene) diphenyl ether and other triazenes passed the DIN 4102-1 test with B2 classification. It is noteworthy that no burning dripping could be detected and the average burning times were very short with exceptionally low weight losses. Therefore, triazene compounds constitute a new and interesting family of radical generators for flame retarding of polymeric materials. The high flame retardant potential of triazenes can be attributed to their ability to generate various types of radicals during their thermal decomposition. According to thermogravimetric analysis/Fourier transform infrared spectroscopy/MS analysis, triazene units are homolytically cleaved into various aminyl, resonance-stabilized aryl radicals, and different CH fragments with simultaneous evolution of elemental nitrogen. Furthermore, the potential of thirteen aliphatic, aromatic, thiuram and heterocyclic substituted organic disulfide derivatives of the general formula R-S-S-R’ as a new group of halogen-free flame retardants for polypropylene films have been investigated. According to the DIN 4102- 1 standard ignitibility test, for the first time it has been demonstrated that many of the disulfides alone can effectively provide flame retardancy and self-extinguishing properties to polypropylene films at already very low concentrations of 0.5 wt.%. For the disulfide family, the highest FR activity was recorded for 5’5’-dithiobis (2-nitrobenzoic acid). Very low values for burning length (53 mm) and burning time (10 s) reflect significantly increased fire retardant performance of this disulfide compared to other compounds in this series as well as to Flamestab® NOR116. Finally, two new, phosphorus-based flame retardants were synthesized: P’P-diphenyl phosphinic hydrazide (PAH) and melamine phenyl phosphonate (MPhP). The DIN 4102-1 test and the more stringent UL94 vertical burning test (UL94 V) were used to assess the formulations ability to extinguish a flame once ignited. A very strong synergistic effect with azoalkanes was found, i.e. in combination with these radical generators even UL94 V0 rate could be obtained.

Stability of Natural Colorants of Plant Origin

In recent years, there have been studies that show a correlation between the hyperactivity of children and use of artificial food additives, including colorants. This has, in part, led to preference of natural products over products with artificial additives. Consumers have also become more aware of health issues. Natural food colorants have many bioactive functions, mainly vitamin A activity of carotenoids and antioxidativity, and therefore they could be more easily accepted by the consumers. However, natural colorant compounds are usually unstable, which restricts their usage. Microencapsulation could be one way to enhance the stability of natural colorant compounds and thus enable better usage for them as food colorants. Microencapsulation is a term used for processes in which the active material is totally enveloped in a coating or capsule, and thus it is separated and protected from the surrounding environment. In addition to protection by the capsule, microencapsulation can also be used to modify solubility and other properties of the encapsulated material, for example, to incorporate fat-soluble compounds into aqueous matrices. The aim of this thesis work was to study the stability of two natural pigments, lutein (carotenoid) and betanin (betalain), and to determine possible ways to enhance their stability with different microencapsulation techniques. Another aim was the extraction of pigments without the use of organic solvents and the development of previously used extraction methods. Stability of pigments in microencapsulated pigment preparations and model foods containing these were studied by measuring the pigment content after storage in different conditions. Preliminary studies on the bioavailability of microencapsulated pigments and sensory evaluation for consumer acceptance of model foods containing microencapsulated pigments were also carried out. Enzyme-assisted oil extraction was used to extract lutein from marigold (Tagetes erecta) flower without organic solvents, and the yield was comparable to solvent extraction of lutein from the same flowers. The effects of temperature, extraction time, and beet:water ratio on extraction efficiency of betanin from red beet (Beta vulgaris) were studied and the optimal conditions for maximum yield and maximum betanin concentration were determined. In both cases, extraction at 40 °C was better than extraction at 80 °C and the extraction for five minutes was as efficient as 15 or 30 minutes. For maximum betanin yield, the beet:water ratio of 1:2 was better, with possibly repeated extraction, but for maximum betanin concentration, a ratio of 1:1 was better. Lutein was incorporated into oil-in-water (o/w) emulsions with a polar oil fraction from oat (Avena sativa) as an emulsifier and mixtures of guar gum and xanthan gum or locust bean gum and xanthan gum as stabilizers to retard creaming. The stability of lutein in these emulsions was quite good, with 77 to 91 percent of lutein being left after storage in the dark at 20 to 22°C for 10 weeks whereas in spray dried emulsions the retention of lutein was 67 to 75 percent. The retention of lutein in oil was also good at 85 percent. Betanin was incorporated into the inner w1 water phase of a water1-in-oil-inwater2 (w1/o/w2) double emulsion with primary w1/o emulsion droplet size of 0.34 μm and secondary w1/o/w2 emulsion droplet size of 5.5 μm and encapsulation efficiency of betanin of 89 percent. In vitro intestinal lipid digestion was performed on the double emulsion, and during the first two hours, coalescence of the inner water phase droplets was observed, and the sizes of the double emulsion droplets increased quickly because of aggregation. This period also corresponded to gradual release of betanin, with a final release of 35 percent. The double emulsion structure was retained throughout the three-hour experiment. Betanin was also spray dried and incorporated into model juices with different pH and dry matter content. Model juices were stored in the dark at -20, 4, 20–24 or 60 °C (accelerated test) for several months. Betanin degraded quite rapidly in all of the samples and higher temperature and a lower pH accelerated degradation. Stability of betanin was much better in the spray dried powder, with practically no degradation during six months of storage in the dark at 20 to 24 °C and good stability also for six months in the dark at 60 °C with 60 percent retention. Consumer acceptance of model juices colored with spray dried betanin was compared with similar model juices colored with anthocyanins or beet extract. Consumers preferred beet extract and anthocyanin colored model juices over juices colored with spray dried betanin. However, spray dried betanin did not impart any off-odors or off-flavors into the model juices contrary to the beet extract. In conclusion, this thesis describes novel solvent-free extraction and encapsulation processes for lutein and betanin from plant sources. Lutein showed good stability in oil and in o/w emulsions, but slightly inferior in spray dried emulsions. In vitro intestinal lipid digestion showed a good stability of w1/o/w2 double emulsion and quite high retention of betanin during digestion. Consumer acceptance of model juices colored with spray dried betanin was not as good as model juices colored with anthocyanins, but addition of betanin to real berry juice could produce better results with mixture of added betanin and natural berry anthocyanins could produce a more acceptable color. Overall, further studies are needed to obtain natural colorants with good stability for the use in food products.

Microencapsulation and tissue engineering as an alternative treatment of diabetes

In the 70's, pancreatic islet transplantation arose as an attractive alternative to restore normoglycemia; however, the scarcity of donors and difficulties with allotransplants, even under immunosuppressive treatment, greatly hampered the use of this alternative. Several materials and devices have been developed to circumvent the problem of islet rejection by the recipient, but, so far, none has proved to be totally effective. A major barrier to transpose is the highly organized islet architecture and its physical and chemical setting in the pancreatic parenchyma. In order to tackle this problem, we assembled a multidisciplinary team that has been working towards setting up the Human Pancreatic Islets Unit at the Chemistry Institute of the University of São Paulo, to collect and process pancreas from human donors, upon consent, in order to produce purified, viable and functional islets to be used in transplants. Collaboration with the private enterprise has allowed access to the latest developed biomaterials for islet encapsulation and immunoisolation. Reasoning that the natural islet microenvironment should be mimicked for optimum viability and function, we set out to isolate extracellular matrix components from human pancreas, not only for analytical purposes, but also to be used as supplementary components of encapsulating materials. A protocol was designed to routinely culture different pancreatic tissues (islets, parenchyma and ducts) in the presence of several pancreatic extracellular matrix components and peptide growth factors to enrich the beta cell population in vitro before transplantation into patients. In addition to representing a therapeutic promise, this initiative is an example of productive partnership between the medical and scientific sectors of the university and private enterprises.

Distribution of liposome-encapsulated antimony in dogs

The achievement of complete cure in dogs with visceral leishmaniasis is currently a great challenge, since dogs are the main reservoir for the transmission of visceral leishmaniasis to humans and they respond poorly to conventional treatment with pentavalent antimonials. In order to improve the efficacy of treatment, we developed a novel formulation for meglumine antimoniate based on the encapsulation of this drug in freeze-dried liposomes (LMA). The aim of the present study was to evaluate the biodistribution of antimony (Sb) in dogs following a single intravenous bolus injection of LMA. Four healthy male mongrel dogs received LMA at 3.8 mg Sb/kg body weight and were sacrificed 3, 48 and 96 h and 7 days later. Antimony was determined in the blood, liver, spleen and bone marrow. In the bone marrow, the highest Sb concentration was observed at 3 h (2.8 µg/g wet weight) whereas in the liver and spleen it was demonstrated at 48 h (43.6 and 102.4 µg/g, respectively). In these organs, Sb concentrations decreased gradually and reached levels of 19.1 µg/g (liver), 28.1 µg/g (spleen) and 0.2 µg/g (bone marrow) after 7 days. Our data suggest that the critical organ for the treatment with LMA could be the bone marrow, since it has low Sb levels and, presumably, high rates of Sb elimination. A multiple dose treatment with LMA seems to be necessary for complete elimination of parasites from bone marrow in dogs with visceral leishmaniasis.

Pressurized hot water flow-through extraction of birch wood

Effective processes to fractionate the main compounds in biomass, such as wood, are a prerequisite for an effective biorefinery. Water is environmentally friendly and widely used in industry, which makes it a potential solvent also for forest biomass. At elevated temperatures over 100 °C, water can readily hydrolyse and dissolve hemicelluloses from biomass. In this work, birch sawdust was extracted using pressurized hot water (PHWE) flow-through systems. The hypothesis of the work was that it is possible to obtain polymeric, water-soluble hemicelluloses from birch sawdust using flow-through PHW extractions at both laboratory and large scale. Different extraction temperatures in the range 140–200 °C were evaluated to see the effect of temperature to the xylan yield. The yields and extracted hemicelluloses were analysed to obtain sugar ratios, the amount of acetyl groups, furfurals and the xylan yields. Higher extraction temperatures increased the xylan yield, but decreased the molar mass of the dissolved xylan. As the extraction temperature increased, more acetic acid was released from the hemicelluloses, thus further decreasing the pH of the extract. There were only trace amounts of furfurals present after the extractions, indicating that the treatment was mild enough not to degrade the sugars further. The sawdust extraction density was increased by packing more sawdust in the laboratory scale extraction vessel. The aim was to obtain extracts with higher concentration than in typical extraction densities. The extraction times and water flow rates were kept constant during these extractions. The higher sawdust packing degree decreased the water use in the extractions and the extracts had higher hemicellulose concentrations than extractions with lower sawdust degrees of packing. The molar masses of the hemicelluloses were similar in higher packing degrees and in the degrees of packing that were used in typical PHWE flow-through extractions. The structure of extracted sawdust was investigated using small angle-(SAXS) and wide angle (WAXS) x-ray scattering. The cell wall topography of birch sawdust and extracted sawdust was compared using x-ray tomography. The results showed that the structure of the cell walls of extracted birch sawdust was preserved but the cell walls were thinner after the extractions. Larger pores were opened inside the fibres and cellulose microfibrils were more tightly packed after the extraction. Acetate buffers were used to control the pH of the extracts during the extractions. The pH control prevented excessive xylan hydrolysis and increased the molar masses of the extracted xylans. The yields of buffered extractions were lower than for plain water extractions at 160–170 °C, but at 180 °C yields were similar to those from plain water and pH buffers. The pH can thus be controlled during extraction with acetate buffer to obtain xylan with higher molar mass than those obtainable using plain water. Birch sawdust was extracted both in the laboratory and pilot scale. The performance of the PHWE flow-through system was evaluated in the laboratory and the pilot scale using vessels with the same shape but different volumes, with the same relative water flow through the sawdust bed, and in the same extraction temperature. Pre-steaming improved the extraction efficiency and the water flow through the sawdust bed. The extracted birch sawdust and the extracted xylan were similar in both laboratory and pilot scale. The PHWE system was successfully scaled up by a factor of 6000 from the laboratory to pilot scale and extractions performed equally well in both scales. The results show that a flow-through system can be further scaled up and used to extract water-soluble xylans from birch sawdust. Extracted xylans can be concentrated, purified, and then used in e.g. films and barriers, or as building blocks for novel material applications.

Energy and raw material consumption analysis of powder bed fusion: case study: CNC machining and laser additive manufacturing

Laser additive manufacturing (LAM), known also as 3D printing, is a powder bed fusion (PBF) type of additive manufacturing (AM) technology used to manufacture metal parts layer by layer by assist of laser beam. The development of the technology from building just prototype parts to functional parts is due to design flexibility. And also possibility to manufacture tailored and optimised components in terms of performance and strength to weight ratio of final parts. The study of energy and raw material consumption in LAM is essential as it might facilitate the adoption and usage of the technique in manufacturing industries. The objective this thesis was find the impact of LAM on environmental and economic aspects and to conduct life cycle inventory of CNC machining and LAM in terms of energy and raw material consumption at production phases. Literature overview in this thesis include sustainability issues in manufacturing industries with focus on environmental and economic aspects. Also life cycle assessment and its applicability in manufacturing industry were studied. UPLCI-CO2PE! Initiative was identified as mostly applied exiting methodology to conduct LCI analysis in discrete manufacturing process like LAM. Many of the reviewed literature had focused to PBF of polymeric material and only few had considered metallic materials. The studies that had included metallic materials had only measured input and output energy or materials of the process and compared to different AM systems without comparing to any competitive process. Neither did any include effect of process variation when building metallic parts with LAM. Experimental testing were carried out to make dissimilar samples with CNC machining and LAM in this thesis. Test samples were designed to include part complexity and weight reductions. PUMA 2500Y lathe machine was used in the CNC machining whereas a modified research machine representing EOSINT M-series was used for the LAM. The raw material used for making the test pieces were stainless steel 316L bar (CNC machined parts) and stainless steel 316L powder (LAM built parts). An analysis of power, time, and the energy consumed in each of the manufacturing processes on production phase showed that LAM utilises more energy than CNC machining. The high energy consumption was as result of duration of production. Energy consumption profiles in CNC machining showed fluctuations with high and low power ranges. LAM energy usage within specific mode (standby, heating, process, sawing) remained relatively constant through the production. CNC machining was limited in terms of manufacturing freedom as it was not possible to manufacture all the designed sample by machining. And the one which was possible was aided with large amount of material removed as waste. Planning phase in LAM was shorter than in CNC machining as the latter required many preparation steps. Specific energy consumption (SEC) were estimated in LAM based on the practical results and assumed platform utilisation. The estimated platform utilisation showed SEC could reduce when more parts were placed in one build than it was in with the empirical results in this thesis (six parts).