A generalized 1D particle transport method for convection diffusion reaction model

This work is devoted to the development of numerical method to deal with convection diffusion dominated problem with reaction term, non - stiff chemical reaction and stiff chemical reaction. The technique is based on the unifying Eulerian - Lagrangian schemes (particle transport method) under the framework of operator splitting method. In the computational domain, the particle set is assigned to solve the convection reaction subproblem along the characteristic curves created by convective velocity. At each time step, convection, diffusion and reaction terms are solved separately by assuming that, each phenomenon occurs separately in a sequential fashion. Moreover, adaptivities and projection techniques are used to add particles in the regions of high gradients (steep fronts) and discontinuities and transfer a solution from particle set onto grid point respectively. The numerical results show that, the particle transport method has improved the solutions of CDR problems. Nevertheless, the method is time consumer when compared with other classical technique e.g., method of lines. Apart from this advantage, the particle transport method can be used to simulate problems that involve movingsteep/smooth fronts such as separation of two or more elements in the system.

Täyteaineen dispergoinnin vaikutus paperin ominaisuuksiin

Kuljetettaessa täyteainetta pidempiä matkoja voidaan aikaan saada säästöjä, mikäli täyteaineliete valmistetaan korkeaan kuiva-ainepitoisuuteen. Dispergointiaineen avulla täyteainelietteen kuiva-ainepitoisuutta voidaan nostaa ilman, että menetetään täyteainelietteen virtausominaisuuksia. Dispergointiaineen tehtävänä on stabiloida täyteaineliete niin, että täyteainepartikkelit pysyvät lietteessä erillään, jolloin lietteen kuiva-ainepitoisuuden kasvattaminen on mahdollista. Täyteainepartikkelien agglomeroituminen estyy, kun dispergointiaine kiinnittyy täyteainepartikkelin pinnalle lisäten partikkelin sähkövarausta ja vahvistaen näin partikkeleiden välisiä repulsiovoimia. Dispergointi on mahdollista tehdä myös steerisellä stabiloinnilla. Yleisimmät käytössä olevat dispergointiaineet ovat polyakryylaatteja. Työssä tutkittiin MBF- laitteella valmistettujen arkkien avulla dispergoinnin vaikutusta täyteaineiden käyttäytymiseen ja paperin ominaisuuksiin. Dispergointiaineen todettiin heikentävän täyteaineen retentiota paperiin, sillä dispergointiaineen aiheuttama täyteaineen anionisuuden kasvu lisää kuidun ja täyteaineen välistä repulsiota. Dispergoitujen täyteaineiden käyttö vaatii retentioaineannoksen kasvattamista, mikä voi johtaa puolestaan formaation heikkenemiseen. Dispergointiaineen todettiin alentavan hienopaperin bulkkia, sillä paksuutta lisääviä agglomeraatteja esiintyi todennäköisesti vähemmän. Lisäksi dispergointiaineen havaittiin heikentävän hienopaperin ja TMP:stä valmistetun paperin optisia ominaisuuksia. Hienopaperilla dispergointiaineen käyttö puolestaan paransi paperin lujuusominaisuuksia. TMP- arkeilla bulkki ja lujuusominaisuudet muuttuivat dispergointiaineannostuksen myötä. 5 ‰:n dispergointiaineannostuksella päästiin samaan bulkkiin sekä lujuusominaisuuksiin kuin ei-dispergoidulla täyteaineella.

Quantification of Proteins and Cells: Luminometric Nonspecific Particle-Based Methods

New luminometric particle-based methods were developed to quantify protein and to count cells. The developed methods rely on the interaction of the sample with nano- or microparticles and different principles of detection. In fluorescence quenching, timeresolved luminescence resonance energy transfer (TR-LRET), and two-photon excitation fluorescence (TPX) methods, the sample prevents the adsorption of labeled protein to the particles. Depending on the system, the addition of the analyte increases or decreases the luminescence. In the dissociation method, the adsorbed protein protects the Eu(III) chelate on the surface of the particles from dissociation at a low pH. The experimental setups are user-friendly and rapid and do not require hazardous test compounds and elevated temperatures. The sensitivity of the quantification of protein (from 40 to 500 pg bovine serum albumin in a sample) was 20-500-fold better than in most sensitive commercial methods. The quenching method exhibited low protein-to-protein variability and the dissociation method insensitivity to the assay contaminants commonly found in biological samples. Less than ten eukaryotic cells were detected and quantified with all the developed methods under optimized assay conditions. Furthermore, two applications, the method for detection of the aggregation of protein and the cell viability test, were developed by utilizing the TR-LRET method. The detection of the aggregation of protein was allowed at a more than 10,000 times lower concentration, 30 μg/L, compared to the known methods of UV240 absorbance and dynamic light scattering. The TR-LRET method was combined with a nucleic acid assay with cell-impermeable dye to measure the percentage of dead cells in a single tube test with cell counts below 1000 cells/tube.

Katupölyn torjunta hiekoitushiekan poistossa kaupunkiympäristössä

Katupölyn torjumisessa hiekoitushiekan poistossa kaupunkiympäristössä tutkittiin, miten katujen talvikunnossapidon toimenpiteet ja talven hiekoitushiekkojen poistotyö vaikuttavat yhdyskuntailman hengitettävien hiukkasten PM10 -katupölyn määrään ja selvitettiin nykyiset käytännöt sekä uusia menetelmiä vähentää katupölyn määrää. Tutkimus on tehty Lappeenrannan kaupungin teknisen toimen katujen kunnossapidon tulosalueelle. Hankkeessa keskityttiin löytämään uusi ja tehokkaampi työmenetelmä sekä työjärjestys hiekanpoistoon, jotta työnaikaisen katupölyn määrä saataisiin minimoitua. Tehokkaita menetelmiä tutkimuksen perusteella olivat katujen ennalta kastelua ja työnaikainen pölynsidonta suolaliuoksella katupölyn vähentämiseen sekä oikean menetelmän käyttö. Pölynsidonta suolaliuoksella osoittautui tehokkaaksi akuutin katupölyn vähentämiskeinoksi. Pölynsidonta ei kuitenkaan poista katupölyä ja puhdistus tulee tehdä myöhemmin. Kadunvarren lumessa on suuria hiekoitushiekan kiintoainespitoisuuksia ja lumen poisviennillä voidaan saavuttaa hyötyjä katupölyongelman kannalta. Hiekoituspäivien lukumäärä on myös suoraan verrannollinen katupölyn määrään. Hiekoituksen ohella myös nastarenkaiden käyttö lisää katupölypäästöjä kaupunkialueilla. Nastarenkaiden vaikutusta katupölyn määrään ei selvitetty tässä tutkimuksessa tarkemmin, koska nastarenkaiden käyttökiellon voidaan olettaa lisäävän liikennetapaturmia sekä myös liukkaudentorjunnan tarvetta, eli hiekoitusta.

Crop residues on short-term CO2 emissions in sugarcane production areas

The proper management of agricultural crop residues could produce benefits in a warmer, more drought-prone world. Field experiments were conducted in sugarcane production areas in the Southern Brazil to assess the influence of crop residues on the soil surface in short-term CO2 emissions. The study was carried out over a period of 50 days after establishing 6 plots with and without crop residues applied to the soil surface. The effects of sugarcane residues on CO2 emissions were immediate; the emissions from residue-covered plots with equivalent densities of 3 (D50) and 6 (D100) t ha-1 (dry mass) were less than those from non-covered plots (D0). Additionally, the covered fields had lower soil temperatures and higher soil moisture for most of the studied days, especially during the periods of drought. Total emissions were as high as 553.62 ± 47.20 g CO2 m-2, and as low as 384.69 ± 31.69 g CO2 m-2 in non-covered (D0) and covered plot with an equivalent density of 3 t ha-1 (D50), respectively. Our results indicate a significant reduction in CO2 emissions, indicating conservation of soil carbon over the short-term period following the application of sugarcane residues to the soil surface.

Control of ammonia emissions in naturally ventilated dairy cattle facilities in Portugal

We conducted a study of the processes associated to NH3 emission in naturally ventilated dairy cattle facilities, having described factors that regulate NH3 emission, as well as methodologies for measuring these emissions at these facilities. Appropriate techniques to mitigate NH3 emission in facilities located in regions with warm climates were also identified. The most effective mitigation techniques with simple implementation include strategies associated to: (i) installation design and flooring, which lead to reduced emissions, (ii) excreta pre-excretion, namely the use of diets with optimized crude protein content and increased milk production at farm level; and (iii) excreta post-excretion, particularly by changing the conditions of environmental monitoring within the premises, practice introduction or additive application in the management of excreta deposited on floors.

Development of simple and efficient synthetic strategies for production of fine chemicals of pharmaceutical relevance : metal-mediated allylation combined with applied catalysis

Den snart 200 år gamla vetenskapsgrenen organisk synteskemi har starkt bidragit till moderna samhällens välfärd. Ett av flaggskeppen för den organiska synteskemin är utvecklingen och produktionen av nya läkemedel och speciellt de aktiva substanserna däri. Därmed är det viktigt att utveckla nya syntesmetoder, som kan tillämpas vid framställningen av farmaceutiskt relevanta målstrukturer. I detta sammanhang är den ultimata målsättningen dock inte endast en lyckad syntes av målmolekylen, utan det är allt viktigare att utveckla syntesrutter som uppfyller kriterierna för den hållbara utvecklingen. Ett av de centralaste verktygen som en organisk kemist har till förfogande i detta sammanhang är katalys, eller mera specifikt möjligheten att tillämpa olika katalytiska reaktioner vid framställning av komplexa målstrukturer. De motsvarande industriella processerna karakteriseras av hög effektivitet och minimerad avfallsproduktion, vilket naturligtvis gynnar den kemiska industrin samtidigt som de negativa miljöeffekterna minskas avsevärt. I denna doktorsavhandling har nya syntesrutter för produktion av finkemikalier med farmaceutisk relevans utvecklats genom att kombinera förhållandevis enkla transformationer till nya reaktionssekvenser. Alla reaktionssekvenser som diskuteras i denna avhandling påbörjades med en metallförmedlad allylering av utvalda aldehyder eller aldiminer. De erhållna produkterna innehållende en kol-koldubbelbindning med en närliggande hydroxyl- eller aminogrupp modifierades sedan vidare genom att tillämpa välkända katalytiska reaktioner. Alla syntetiserade molekyler som presenteras i denna avhandling karakteriseras som finkemikalier med hög potential vid farmaceutiska tillämpningar. Utöver detta tillämpades en mängd olika katalytiska reaktioner framgångsrikt vid syntes av dessa molekyler, vilket i sin tur förstärker betydelsen för de katalytiska verktygen i organiska kemins verktygslåda.

”Iha fine. Paljon parempaa kuin edellisessä koulussa!” Kyselytutkimus loimaalaisten kahdeksas- ja yhdeksäsluokkalaisten kouluruokailusta ja kouluruokailutottumuksista

Tutkimuksella tarkasteltiin yläkoululaisten kouluruokailun ajankohtaisia ilmiöitä sekä selvitettiin kouluruokailutottumusten ja oppilaiden taustamuuttujien (sukupuoli, painoindeksi, fyysinen kunto ja aktiivisuus, uni ja väsyneisyys sekä koulumenestys) mahdollista yhteyttä. Tutkimuksen kohderyhmä muodostui Loimaan kaupungissa sijaitsevista Puistokadun ja Opintien koulun kahdeksas- ja yhdeksäsluokkalaisista oppilaista. Tutkimus suoritettiin kyselyyn osallistuneilla kouluilla marraskuun alussa 2011, jolloin tutkimukseen osallistui molemmista kouluista 69 oppilasta kokonaisotannan ollessa 138 oppilasta. Tutkimusjoukko koostui 65 tytöstä ja 72 pojasta. Tämä tutkimus on tutkimusotteeltaan pääosin kvantitatiivinen, mutta siinä esiintyy myös kvalitatiivisia piirteitä. Tutkimusmenetelmänä käytettiin strukturoituja ja avoimia kysymyksiä sisältävää kyselylomaketta, joka oli muodostettu tätä tutkimusta varten aiempien tutkimuksien pohjalta. Tutkimuksen tulokset olivat myönteisiä kouluruokailun osalta. Oppilaiden antama keskiarvo kouluruoalle oli 7,5 arvosteluasteikon ollessa neljästä kymmeneen. Oppilaista 86 prosenttia osallistui kouluruokailuun päivittäin ja 83 prosenttia viihtyi kouluruokalassa yli kymmenen minuuttia. Oppilaat söivät ruoka-aineiden välisiä suhteita kuvaavan lautasmallin eri osia hyvin. Oppilaat toivoivat kouluruokailuunsa enemmän jälkiruokia ja pehmeää leipää sekä paremmanmakuista pääruokaa. Oppilaiden taustamuuttujia tarkastellessa havaittiin niillä olevan yhteyksiä oppilaiden kouluruokailutottumuksiin, mutta tilastollisesti tarkasteltuna yhteydet eivät olleet merkitseviä. Ainoastaan yöunien keston ja väsyneisyyden yhteys kouluruokailutottumuksiin oli melkein merkitsevää. Tutkimukseen osallistuneet oppilaat eivät noudattaneet vähähiilihydraattista ruokavaliota, joten ”karppauksella” ei ollut vaikutuksia kouluruokailuun. Tutkimuksen tuloksia verrattaessa laajempiin tutkimuksiin (Terveyden ja hyvinvoinnin laitos 2011; Hoppu ym. 2008; Urho & Hasunen 2004), voidaan todeta tutkimukseen osallistuneiden oppilaiden pitävän kouluruoasta ja kouluruokailusta enemmän kuin ikätoverinsa. Oppilaat osallistuivat aktiivisemmin kouluruokailuun, söivät lautasmallin osia paremmin ja viettivät enemmän aikaa kouluruokailussa.

Acidic dissolution of iron oxides and regeneration of a ceramic filter medium

The dewatering of iron ore concentrates requires large capacity in addition to producing a cake with low moisture content. Such large processes are commonly energy intensive and means to lower the specific energy consumption are needed. Ceramic capillary action disc filters incorporate a novel filter medium enabling the harnessing of capillary action, which results in decreased energy consumption in comparison to traditional filtration technologies. As another benefit, the filter medium is mechanically and chemically more durable than, for example, filter cloths and can, thus, withstand harsh operating conditions and possible regeneration better than other types of filter media. In iron ore dewatering, the regeneration of the filter medium is done through a combination of several techniques: (1) backwashing, (2) ultrasonic cleaning, and (3) acid regeneration. Although it is commonly acknowledged that the filter medium is affected by slurry particles and extraneous compounds, published research, especially in the field of dewatering of mineral concentrates, is scarce. Whereas the regenerative effect of backwashing and ultrasound are more or less mechanical, regeneration with acids is based on chemistry. The chemistry behind the acid regeneration is, naturally, dissolution. The dissolution of iron oxide particles has been extensively studied over several decades but those studies may not necessarily be directly applicable in the regeneration of the filter medium which has undergone interactions with the slurry components. The aim of this thesis was to investigate if free particle dissolution indeed correlates with the regeneration of the filter medium. For this purpose, both free particle dissolution and dissolution of surface adhered particles were studied. The focus was on acidic dissolution of iron oxide particles and on the study of the ceramic filter medium used in the dewatering of iron ore concentrates. The free particle dissolution experiments show that the solubility of synthetic fine grained iron oxide particles in oxalic acid could be explained through linear models accounting for the effects of temperature and acid concentration, whereas the dissolution of a natural magnetite is not so easily explained by such models. In addition, the kinetic experiments performed both support and contradict the work of previous authors: the suitable kinetic model here supports previous research suggesting solid state reduction to be the reaction mechanism of hematite dissolution but the formation of a stable iron oxalate is not supported by the results of this research. Several other dissolution mechanisms have also been suggested for iron oxide dissolution in oxalic acid, indicating that the details of oxalate promoted reductive dissolution are not yet agreed and, in this respect, this research offers added value to the community. The results of the regeneration experiments with the ceramic filter media show that oxalic acid is highly effective in removing iron oxide particles from the surface of the filter medium. The dissolution of those particles did not, however, exhibit the expected behaviour, i.e. complete dissolution. The results of this thesis show that although the regeneration of the ceramic filter medium with acids incorporates the dissolution of slurry particles from the surface of the filter medium, the regeneration cannot be assessed purely based upon free particle dissolution. A steady state, dependent on temperature and on the acid concentration, was observed in the dissolution of particles from the surface even though the limit of solubility of free iron oxide particles had not been reached. Both the regeneration capacity and efficiency, with regards to the removal of iron oxide particles, was found to be temperature dependent, but was not affected by the acid concentration. This observation further suggests that the removal of the surface adhered particles does not follow the dissolution of free particles, which do exhibit a dependency on the acid concentration. In addition, changes in the permeability and in the pore structure of the filter medium were still observed after the bulk concentration of dissolved iron had reached a steady state. Consequently, the regeneration of the filter medium continued after the dissolution of particles from the surface had ceased. This observation suggests that internal changes take place at the final stages of regeneration. The regeneration process could, in theory, be divided into two, possibly overlapping, stages: (1) dissolution of surface-adhered particles, and (2) dissolution of extraneous compounds from within the pore structure. In addition to the fundamental knowledge generated during this thesis, tools to assess the effects of parameters on the regeneration of the ceramic filter medium are needed. It has become clear that the same tools used to estimate the dissolution of free particles cannot be used to estimate the regeneration of a filter medium unless only a robust characterisation of the order of regeneration efficiency is needed.

Utilization of Particle Image velocimetry in PPOOLEX condensation experiments

Particle Image Velocimetry, PIV, is an optical measuring technique to obtain velocity information of a flow in interest. With PIV it is possible to achieve two or three dimensional velocity vector fields from a measurement area instead of a single point in a flow. Measured flow can be either in liquid or in gas form. PIV is nowadays widely applied to flow field studies. The need for PIV is to obtain validation data for Computational Fluid Dynamics calculation programs that has been used to model blow down experiments in PPOOLEX test facility in the Lappeenranta University of Technology. In this thesis PIV and its theoretical background are presented. All the subsystems that can be considered to be part of a PIV system are presented as well with detail. Emphasis is also put to the mathematics behind the image evaluation. The work also included selection and successful testing of a PIV system, as well as the planning of the installation to the PPOOLEX facility. Already in the preliminary testing PIV was found to be good addition to the measuring equipment for Nuclear Safety Research Unit of LUT. The installation to PPOOLEX facility was successful even though there were many restrictions considering it. All parts of the PIV system worked and they were found out to be appropriate for the planned use. Results and observations presented in this thesis are a good background to further PIV use.

Microstructural and environmental effects on the mechanical properties of porous particle-polymer composites

Papper kan anses vara ett av de mest använda materialen i det dagliga livet. Tidskrifter, tidningar, böcker och diverse förpackningar är några exempel på pappersbaserade produkter. Papperets egenskaper måste anpassas till användningsändamålet. En tidskrift kräver t.ex. hög ljushet, opacitet och en slät yta hos papperet, medan dessa egenskaper är mindre viktiga för en dagstidning. Allt tryckpapper behöver vissa mekaniska egenskaper för att tåla vidarebearbetning såsom kalandrering, tryckning och vikning. Man kan bestryka papper för att förbättra dess optiska egenskaper och tryckbarhetsegenskaper. Vid bestrykning appliceras en dispersion av mineralpigment och polymerbindemedel som ett tunt lager på papperets yta. Bestrykningsskiktet kan ses som ett komplext, poröst kompositmaterial som även bidrar till papperets mekaniska egenskaper och dess processerbarhet i diverse konverteringsoperationer. Kravet på framställning av förmånligt papper med tillräckliga styrkeegenskaper ställer allt högre krav på optimeringen av pappersbestrykningsskiktets egenskaper och produktionskostnader. Målet med detta arbete var att förstå sambandet mellan pigmentbestrykningsskiktets mikrostruktur och dess makroskopiska, mekaniska egenskaper. Resultaten visar att adhesionen i gränsytan mellan pigment och bindemedel är kritisk för bestrykningsskiktets förmåga att bära mekanisk belastning. Polära vätskor är vanliga i tryckfärger och kan, eftersom de påverkar syra/bas-interaktionerna mellan pigment och latexbindemedel, försvaga denna adhesion. Resultaten tyder på att ytstyrkan hos bestruket papper kan höjas genom användning av bifunktionella dispergeringsmedel för mineralpigment. Detta medför inbesparingar i pappersproduktionen eftersom mängden bindemedel, den dyraste komponenten i bestrykningsskiktet, kan minskas.

Oxidation rates of carbon and nitrogen in char residues from solid fuels

Computational fluid dynamics (CFD) modeling is an important tool in designing new combustion systems. By using CFD modeling, entire combustion systems can be modeled and the emissions and the performance can be predicted. CFD modeling can also be used to develop new and better combustion systems from an economical and environmental point of view. In CFD modeling of solid fuel combustion, the combustible fuel is generally treated as single fuel particles. One of the limitations with the CFD modeling concerns the sub-models describing the combustion of single fuel particles. Available models in the scientific literature are in many cases not suitable as submodels for CFD modeling since they depend on a large number of input parameters and are computationally heavy. In this thesis CFD-applicable models are developed for the combustion of single fuel particles. The single particle models can be used to improve the combustion performance in various combustion devices or develop completely new technologies. The investigated fields are oxidation of carbon (C) and nitrogen (N) in char residues from solid fuels. Modeled char-C oxidation rates are compared to experimental oxidation rates for a large number of pulverized solid fuel chars under relevant combustion conditions. The experiments have been performed in an isothermal plug flow reactor operating at 1123-1673 K and 3-15 vol.% O2. In the single particle model, the char oxidation is based on apparent kinetics and depends on three fuel specific parameters: apparent pre-exponential factor, apparent activation energy, and apparent reaction order. The single particle model can be incorporated as a sub-model into a CFD code. The results show that the modeled char oxidation rates are in good agreement with experimental char oxidation rates up to around 70% of burnout. Moreover, the results show that the activation energy and the reaction order can be assumed to be constant for a large number of bituminous coal chars under conditions limited by the combined effects of chemical kinetics and pore diffusion. Based on this, a new model based on only one fuel specific parameter is developed (Paper III). The results also show that reaction orders of bituminous coal chars and anthracite chars differ under similar conditions (Paper I and Paper II); reaction orders of bituminous coal chars were found to be one, while reaction orders of anthracite chars were determined to be zero. This difference in reaction orders has not previously been observed in the literature and should be considered in future char oxidation models. One of the most frequently used comprehensive char oxidation models could not explain the difference in the reaction orders. In the thesis (Paper II), a modification to the model is suggested in order to explain the difference in reaction orders between anthracite chars and bituminous coal chars. Two single particle models are also developed for the NO formation and reduction during the oxidation of single biomass char particles. In the models the char-N is assumed to be oxidized to NO and the NO is partly reduced inside the particle. The first model (Paper IV) is based on the concentration gradients of NO inside and outside the particle and the second model is simplified to such an extent that it is based on apparent kinetics and can be incorporated as a sub-model into a CFD code (Paper V). Modeled NO release rates from both models were in good agreement with experimental measurements from a single particle reactor of quartz glass operating at 1173-1323 K and 3-19 vol.% O2. In the future, the models can be used to reduce NO emissions in new combustion systems.

Paper for printed electronics and functionality

Mass-produced paper electronics (large area organic printed electronics on paper-based substrates, “throw-away electronics”) has the potential to introduce the use of flexible electronic applications in everyday life. While paper manufacturing and printing have a long history, they were not developed with electronic applications in mind. Modifications to paper substrates and printing processes are required in order to obtain working electronic devices. This should be done while maintaining the high throughput of conventional printing techniques and the low cost and recyclability of paper. An understanding of the interactions between the functional materials, the printing process and the substrate are required for successful manufacturing of advanced devices on paper. Based on the understanding, a recyclable, multilayer-coated paper-based substrate that combines adequate barrier and printability properties for printed electronics and sensor applications was developed in this work. In this multilayer structure, a thin top-coating consisting of mineral pigments is coated on top of a dispersion-coated barrier layer. The top-coating provides well-controlled sorption properties through controlled thickness and porosity, thus enabling optimizing the printability of functional materials. The penetration of ink solvents and functional materials stops at the barrier layer, which not only improves the performance of the functional material but also eliminates potential fiber swelling and de-bonding that can occur when the solvents are allowed to penetrate into the base paper. The multi-layer coated paper under consideration in the current work consists of a pre-coating and a smoothing layer on which the barrier layer is deposited. Coated fine paper may also be used directly as basepaper, ensuring a smooth base for the barrier layer. The top layer is thin and smooth consisting of mineral pigments such as kaolin, precipitated calcium carbonate, silica or blends of these. All the materials in the coating structure have been chosen in order to maintain the recyclability and sustainability of the substrate. The substrate can be coated in steps, sequentially layer by layer, which requires detailed understanding and tuning of the wetting properties and topography of the barrier layer versus the surface tension of the top-coating. A cost competitive method for industrial scale production is the curtain coating technique allowing extremely thin top-coatings to be applied simultaneously with a closed and sealed barrier layer. The understanding of the interactions between functional materials formulated and applied on paper as inks, makes it possible to create a paper-based substrate that can be used to manufacture printed electronics-based devices and sensors on paper. The multitude of functional materials and their complex interactions make it challenging to draw general conclusions in this topic area. Inevitably, the results become partially specific to the device chosen and the materials needed in its manufacturing. Based on the results, it is clear that for inks based on dissolved or small size functional materials, a barrier layer is beneficial and ensures the functionality of the printed material in a device. The required active barrier life time depends on the solvents or analytes used and their volatility. High aspect ratio mineral pigments, which create tortuous pathways and physical barriers within the barrier layer limit the penetration of solvents used in functional inks. The surface pore volume and pore size can be optimized for a given printing process and ink through a choice of pigment type and coating layer thickness. However, when manufacturing multilayer functional devices, such as transistors, which consist of several printed layers, compromises have to be made. E.g., while a thick and porous top-coating is preferable for printing of source and drain electrodes with a silver particle ink, a thinner and less absorbing surface is required to form a functional semiconducting layer. With the multilayer coating structure concept developed in this work, it was possible to make the paper substrate suitable for printed functionality. The possibility of printing functional devices, such as transistors, sensors and pixels in a roll-to-roll process on paper is demonstrated which may enable introducing paper for use in disposable “onetime use” or “throwaway” electronics and sensors, such as lab-on-strip devices for various analyses, consumer packages equipped with product quality sensors or remote tracking devices.

The effects of location, feedstock availability, and supply-chain logistics on the greenhouse gas emissions of forest-biomass energy utilization in Finland

Forest biomass represents a geographically distributed feedstock, and geographical location affects the greenhouse gas (GHG) performance of a given forest-bioenergy system in several ways. For example, biomass availability, forest operations, transportation possibilities and the distances involved, biomass end-use possibilities, fossil reference systems, and forest carbon balances all depend to some extent on location. The overall objective of this thesis was to assess the GHG emissions derived from supply and energy-utilization chains of forest biomass in Finland, with a specific focus on the effect of location in relation to forest biomass’s availability and the transportation possibilities. Biomass availability and transportation-network assessments were conducted through utilization of geographical information system methods, and the GHG emissions were assessed by means of lifecycle assessment. The thesis is based on four papers in which forest biomass supply on industrial scale was assessed. The feedstocks assessed in this thesis include harvesting residues, smalldiameter energy wood and stumps. The principal implication of the findings in this thesis is that in Finland, the location and availability of biomass in the proximity of a given energyutilization or energy-conversion plant is not a decisive factor in supply-chain GHG emissions or the possible GHG savings to be achieved with forest-biomass energy use. Therefore, for the greatest GHG reductions with limited forest-biomass resources, energy utilization of forest biomass in Finland should be directed to the locations where most GHG savings are achieved through replacement of fossil fuels. Furthermore, one should prioritize the types of forest biomass with the lowest direct supply-chain GHG emissions (e.g., from transport and comminution) and the lowest indirect ones (in particular, soil carbon-stock losses), regardless of location. In this respect, the best combination is to use harvesting residues in combined heat and power production, replacing peat or coal.

Effect of particle morphology on the mechanical and thermo-mechanical behavior of polymer composites

Fiber reinforced polymer composites have been used in many applications, such as in automobile, aerospace and naval industries, due basically to their high strength-to-weight and modulus-to-weight, among other properties. Even though particles are usually not able to lead to the level of reinforcement of fibers, particle reinforced polymer composites have been proposed for many new applications due to their low cost, easy fabrication and isotropic properties. In this work, polymer composites were prepared by incorporating glass particles of different morphologies on poly(aryl sulfones) matrices. Particles with aspect ratios equal to 1, 2.5 and 10 were used. The prepared composites were characterized using electron microscopy and thermal analysis. Mechanical properties of the composites were evaluated using a four-point bending test. The thermo-mechanical behavior of the obtained composites was also investigated. The results showed that the morphology of the particles alter significantly the mechanical properties of composites. Particles with larger values of aspect ratio led to large elastic modulus but low levels of strain at failure. This result was explained by modeling the thermo-mechanical behavior of the composites using a viscoelastic model. Parameters of the model, obtained from a Cole-Cole type of plot, demonstrated that interactions at the polymer-reinforcing agent interface were higher for composites with large aspect ratio particles. Higher levels of interactions at interfaces can lead to higher degrees of stress transfer and, consequently, to composites with large elastic modulus, as experimentally observed.