In this thesis, a number of commercially available paper substrates of various types are characterized and their characteristics related to the performance of inkjet-printed conductors using silver nanoparticle ink. The evaluated performance variables are electrical conductivity as well as the minimum achievable conductor width and the edge raggedness. It is shown that quick absorption of the ink carrier is beneficial for achieving well defined conductor geometry and high conductivity. Surface roughness with topography variations of sufficiently large amplitude and frequency is detrimental to print definition and conductivity. Porosity is another important factor, where the characteristic pore size is much more important than the total pore volume. A nearly ideal porous coating has large total pore volume but small characteristic pore size, preferably smaller than individual nanoparticles in the ink. Apparent surface energy is important for non-absorbing substrates but of limited importance for coatings with a high absorption rate.Additionally, a concept for improving the geometric definition of inkjet-printed conductors on nonporous films has been demonstrated. By coating the films with polymer–based coatings to provide a means of ink solvent removal, minimum conductor width were reduced a factor 2 or more.Intimately connected to the end performance of printed conductors is a well adapted sintering methodology. A comparative evaluation of a number of selective sintering methods has been performed on paper substrates with different heat tolerance. Pulsed high-power white light was found to be a good compromise between conductivity performance, reliability and production adaptability.The purpose of the work conducted in this thesis is to increase the knowledge base in how surface characteristics of papers and flexible films affect performance of printed nanoparticle structures. This would improve selection, adaption of, or manufacturing of such substrates to suit printed high conductivity patterns such as printed antennas for packaging. / I denna avhandling har ett antal kommersiellt tillgängliga papper av olika typ karaktäriserats och deras egenskaper relaterats till prestandan på inkjet-tryckta elektriska ledare tryckta med silvernanopartikelbläck. De undersökta prestandavariablerna är elektrisk ledningsförmåga samt ledarnas minimala linjebredd och kantjämnhet. Det visas att en snabb absorption av bläckets lösningsmedel är gynnsam för både väldefinierad ledningsgeometri och elektrisk ledningsförmåga. Ytråhet med topografiska variationer med tillräckligt stor amplitud och spatiell frekvens korrelerar negativt med tryckdefinition och ledningsförmåga. Porositet är ytterligare en viktig faktor, där karaktäristisk porstorlek är avsevärt viktigare än total porvolym. Nära ideala egenskaper hos en porös bestrykning synes vara en mycket hög total porvolym men med små individuella porer, med fördel mindre än de minsta metallpartiklarna i bläcket. Ytenergi är mycket betydelsefull för icke-absorberande substrat men tappar nästan all sin betydelse för bestrykningar med snabb absorption.Ett koncept för att förbättra den geometriska definitionen på inkjet-tryckta ledare på icke-porösa flexibla filmer har visats. Genom att bestryka filmerna med vissa polymerbaserade material och därmed införa en mekanism för separering av lösningsmedel och partiklar så reducerades ledarnas minimibredd med en faktor 2 eller mer.Intimt förknippad med den slutliga elektriska prestandan på tryckta ledare är också en väl anpassad sintringsmetodik. En jämförande utvärdering av ett flertal selektiva sintringmetoder har genomförts på papper med olika värmetålighet. Pulsat vitt ljus med hög effekt bedömdes som en bra kompromiss mellan elektriska prestanda, tillförlitlighet och anpassningsbarhet för produktionsmiljö.Nyttan med arbetet som presenteras i denna avhandling är att öka kunskapsbasen för hur pappers och flexibla filmers ytegenskaper påverkar prestandan på inkjet-tryckta nanopartikelstrukturer. Detta möjliggör bättre urval, anpassning av, eller tillverkning av sådana substrat för att passa tryckta mönster med hög konduktivitet; som till exempel tryckta antenner på förpackningar.

Recently, Internet has been used widely. Many scholar digital libraries have also followed this trend and grown up quickly. However, information in these digital libraries is complex and huge. Users are difficult to discover papers they need; instead, they often get lost in the information. When they search these digital libraries, they are also limited to the documents which are embodied in these digital libraries, and can not locate important papers in other journals. Citation Analysis has been used in many areas and it is used in this research to build an expert system. Further, we will discover important papers which can represent these research areas. We called these papers as ¡§Key Papers¡¨. A citation can be classified by its relation as ¡§Direct Citation¡¨ and ¡§Indirect Citation¡¨. Many researchers showed that indirect citations held influence, but in the past they just used direct citations to calculate importance and neglected indirect citations. This research combined direct and indirect relations into one index, and used this index to build the expert system. In addition, we provided a visualization of papers¡¦ citation relations, and helped users to find key papers in their research areas. In order to test our system, we collected the top six journals in MIS, totally 7579 papers, and extracted 129114 citations from these papers. The result showed no differences between direct and indirect citations. However, key papers that didn¡¦t belong to these journals could be discovered, and using top three journals could obtain the same result as found in using top six journals.

Paper is a network material composed of a great number of fibers that interact with each other through fiber joints. In order to make a clear statement regarding observed changes being made in paper, it is vital to determine the structural level of paper that is being affected by chemical modifications. Polyelectrolytes having a wide range in molecular properties have been synthesized to investigate the adsorption behavior of cationic polyelectrolytes to cellulosic fibers. The interaction with the porous cell wall of cellulosic fibers is governed by the molecular properties of the polyelectrolyte. More specifically, polyelectrolytes having a low charge density are able to penetrate into the fiber cell wall, while high charge density polyelectrolytes are restricted to the exterior fiber surface. The molecular mass also influences the extent to which adsorption occurs within the cell wall, although this is typically only pronounced for low charge density polyelectrolytes. High charge density polyelectrolytes are generally restricted to the fiber surface due to strong Coulombic interactions between charged groups along the molecular backbone, which create a stiff molecular conformation. These results were confirmed by fluorescent labeling techniques, which allow the polyelectrolytes to be tracked inside the cell wall by confocal laser scanning microscopy. This approach was also used to demonstrate the effect of an electrolyte, which screens the Coulombic interactions and facilitates penetration into the cell wall. However, a considerable difference in the adsorption behavior of polyelectrolytes having similar molecular mass is still observed at high electrolyte concentration, where the electrostatic contributions are negligible. These differences are a consequence of a diffusion process that occurs on a longer times scale. Although polyelectrolyte adsorption to cellulosic fibers reaches a pseudo-equilibrium at short times, a driving force into the cell wall exists due to the bulk charge of the fiber. The time scale of this diffusion process depends on the polyelectrolyte properties, and was observed to persist for over 3 months. As the extent to which these polyelectrolytes penetrate into the cell wall has been ascertained, and the fibers can be crosslinked to different degrees in the cell wall or at the surface. Cationic acetal dextran was prepared as a model crosslinking agent, as the molecular mass, charge density and degree of acetal substitution can readily be controlled during synthesis. A considerable effect on the tensile properties and fracture toughness was observed for crosslinked paper, which could be attributed to either the fibers or the fiber joints. Crosslinking acted to stiffen the fibers and the fiber joints, which influenced the transfer of applied stresses through the paper structure. Changes in the material behavior at high relative humidity could be improved by crosslinking the fibers at the correct the structural level. / QC 20100811

In this study, novel bio-inks formulated with horseradish peroxidase, HRP, and some additives were successfully developed for piezoelectric inkjet application. The optimized bio-ink formulation had a reliable jetting performance and maintained the biofunctionality before and after printing. The bio-ink also demonstrated a good storage life for up to 40 days at 4 oC with a negligible loss of biofunctionality. However, it was observed that some additives used in the bio-ink for obtaining necessary operational characteristics had detrimental effects on the enzyme activity. Especially, it was found that various viscosity modifiers typically used in commercial inkjet inks significantly impaired HRP activity prior to printing. Sodium Carboxymethyl Cellulose was shown to be an effective viscosity modifier that had no adverse effect on the biological activity of the HRP enzyme. Using a confocal scanning fluorescent microscope, a method for characterizing the spatial distribution of the active enzyme within the cellulosic paper substrates after inkjet printing was developed. Interestingly, it was found that the active printed HRP enzyme was mostly located in the cell walls of the cellulosic fibers instead of near the pigments or fillers. In an effort to better understand the fundamental interactions between the enzyme and the immobilization substrates, HRP adsorption isotherms on various substrate surfaces were obtained using the depletion method. The substrates included not only pulp fibers with varying degree of hydrophobicity and pigment and latex (the key materials used in papermaking), but also other types of cellulosic fibers of different morphologies, crystallinities, porosities, or surface charge densities. The influence on enzyme adsorption and inactivation behaviour of these substrates was compared with that of polystyrene beads (dialysed), which has been well studied in the literature. Results from this thesis indicated that hydrophobic interactions between the enzyme and the substrate surfaces had a major impact on the HRP adsorption behavior, while electrostatic interactions played a minor role. However, strong hydrophobic interactions could lead to enzyme inactivation. Research findings from this study suggested that cellulosic pulp fibers could be tailor-made into excellent enzyme immobilization supports by using existing fiber surface modification techniques.

Magnesium oxide-based additives have been used in kraft recovery boilers to minimize deposit accumulation on superheater and generating bank tubes. Due to inconclusive results observed in boilers and claims made for additive effectiveness backed by little scientific evidence, only a few mills still use the additives for fouling control. A systematic study was performed to examine the effect of MgO-based additives on deposit accumulation and removal under controlled laboratory conditions, and to evaluate the additive effect in a kraft recovery boiler. The results show that while the additive coating has no effect on deposition, it could ease deposit removal if a coating greater than 5 µm can be applied on the tube surface effectively. Separate injection of additive and black liquor had insignificant effect on deposition and removal. Results of the field study show that the amount of additive collected on the tube is too small to have an impact.

Magnesium oxide-based additives have been used in kraft recovery boilers to minimize deposit accumulation on superheater and generating bank tubes. Due to inconclusive results observed in boilers and claims made for additive effectiveness backed by little scientific evidence, only a few mills still use the additives for fouling control. A systematic study was performed to examine the effect of MgO-based additives on deposit accumulation and removal under controlled laboratory conditions, and to evaluate the additive effect in a kraft recovery boiler. The results show that while the additive coating has no effect on deposition, it could ease deposit removal if a coating greater than 5 µm can be applied on the tube surface effectively. Separate injection of additive and black liquor had insignificant effect on deposition and removal. Results of the field study show that the amount of additive collected on the tube is too small to have an impact.

In this study, novel bio-inks formulated with horseradish peroxidase, HRP, and some additives were successfully developed for piezoelectric inkjet application. The optimized bio-ink formulation had a reliable jetting performance and maintained the biofunctionality before and after printing. The bio-ink also demonstrated a good storage life for up to 40 days at 4 oC with a negligible loss of biofunctionality. However, it was observed that some additives used in the bio-ink for obtaining necessary operational characteristics had detrimental effects on the enzyme activity. Especially, it was found that various viscosity modifiers typically used in commercial inkjet inks significantly impaired HRP activity prior to printing. Sodium Carboxymethyl Cellulose was shown to be an effective viscosity modifier that had no adverse effect on the biological activity of the HRP enzyme. Using a confocal scanning fluorescent microscope, a method for characterizing the spatial distribution of the active enzyme within the cellulosic paper substrates after inkjet printing was developed. Interestingly, it was found that the active printed HRP enzyme was mostly located in the cell walls of the cellulosic fibers instead of near the pigments or fillers. In an effort to better understand the fundamental interactions between the enzyme and the immobilization substrates, HRP adsorption isotherms on various substrate surfaces were obtained using the depletion method. The substrates included not only pulp fibers with varying degree of hydrophobicity and pigment and latex (the key materials used in papermaking), but also other types of cellulosic fibers of different morphologies, crystallinities, porosities, or surface charge densities. The influence on enzyme adsorption and inactivation behaviour of these substrates was compared with that of polystyrene beads (dialysed), which has been well studied in the literature. Results from this thesis indicated that hydrophobic interactions between the enzyme and the substrate surfaces had a major impact on the HRP adsorption behavior, while electrostatic interactions played a minor role. However, strong hydrophobic interactions could lead to enzyme inactivation. Research findings from this study suggested that cellulosic pulp fibers could be tailor-made into excellent enzyme immobilization supports by using existing fiber surface modification techniques.

Paper making involves three fabrics: forming, pressing, and drying. The forming fabric is responsible for sheet forming, the initial dewatering of a low concentration pulp suspension into a wet sheet of paper. In the process of forming, topographical and hydrodynamic marks can be transferred from the drainage media (the forming fabric) to the sheet produced. An experimental investigation of a model forming fabric was performed to identify the geometric parameters having the largest influence on hydrodynamic wire mark. The data were also compared with the numerical simulations of Huang. To simplify the problem, justifiable engineering simplifications were made. The second phase (the fibres) was removed and the machine-direction filaments were neglected. This reduced the problem to investigation of flow through a bank of dissimilar cylinders. It was desired to find the most important geometrical parameter to reduce flow non-uniformity in the paper side flow field. Particle image velocimetry, pressure drop and flow visualization tests were conducted to investigate the flow through the array of cylinders. It was found that with a cylinder surface separation of 0.75$\times$ the paper side cylinder diameter the pressure drop tended toward the sum of the rows, and the paper side flow field was nearly identical to the paper side row only flow field, regardless of the backing side cylinder dimensions and configuration. It was seen that when the pressure drop through the bank of cylinders was equal to the sum of the rows' pressure drops the paper side flow field was the same as the paper side row only flow field. As such, pressure drop can act as an indication of when the machine side row will not affect the paper side flow field.

Paper making involves three fabrics: forming, pressing, and drying. The forming fabric is responsible for sheet forming, the initial dewatering of a low concentration pulp suspension into a wet sheet of paper. In the process of forming, topographical and hydrodynamic marks can be transferred from the drainage media (the forming fabric) to the sheet produced. An experimental investigation of a model forming fabric was performed to identify the geometric parameters having the largest influence on hydrodynamic wire mark. The data were also compared with the numerical simulations of Huang. To simplify the problem, justifiable engineering simplifications were made. The second phase (the fibres) was removed and the machine-direction filaments were neglected. This reduced the problem to investigation of flow through a bank of dissimilar cylinders. It was desired to find the most important geometrical parameter to reduce flow non-uniformity in the paper side flow field. Particle image velocimetry, pressure drop and flow visualization tests were conducted to investigate the flow through the array of cylinders. It was found that with a cylinder surface separation of 0.75$\times$ the paper side cylinder diameter the pressure drop tended toward the sum of the rows, and the paper side flow field was nearly identical to the paper side row only flow field, regardless of the backing side cylinder dimensions and configuration. It was seen that when the pressure drop through the bank of cylinders was equal to the sum of the rows' pressure drops the paper side flow field was the same as the paper side row only flow field. As such, pressure drop can act as an indication of when the machine side row will not affect the paper side flow field.

Pulp- and papermills expend vast amounts of water in order to produce pulp, paper and cardboard. Hence, they alsocreate vast amounts of waste water which has to be cleaned before it can be released into the receiving body of water. Insuch a wastewater treatment plant, tremendous amounts of energy are expended by the aeration in the biologicalcleaning process. This aeration is necessary to supply the microorganisms that shall decompose organic material withoxygen, which they need for their metabolism. The transfer of oxygen from the gas phase to the liquid phase isprimarily inhibited by surface-active substances in the waste water like resin acids or fatty acids. The purpose of thisthesis has been to determine if the surface-active substances can be removed by means of chemical pre-precipitationbefore the waste water enters the biological cleaning step. Thus, the efficiency of the aeration shall be improved.In the laboratory, aeration tests were performed for plain water, water with added surface-active substances and CTMPwastewaterfrom Stora Enso Skoghalls Bruk. The test for water with added surface-active substances showed clearlythat these substances have a big influence on the aeration efficiency, which was impaired considerably compared withplain water.In order to determine how chemical precipitation influences the content of surface-active substances, screening trialswere performed with the CTMP waste water. The concentration of surface-active substances was estimated bymeasuring the surface tension of the waste water. The surface tension sinks with increasing concentration of thesesubstances. 250 ml CTMP-wastewater was precipitated with three different chemicals: PAX-XL60, PGA and AVR. Inorder to determine the optimal dosing as well as the optimal pH-value for goal-oriented precipitation of the surfaceactivesubstances, the precipitation was performed with different pH-values between 4 and 8 as well as for differentdoses of the precipitation chemicals. It was discovered that the optimal pH-value for precipitation with PAX-XL60 is7,5 while the precipitation with PGA had the optimal pH-value of 6. The optimal dosage for PAX-XL60 was 10 g/cm3,while the optimal dosage for PGA could not be determined because of the small waste water volume used in thescreening trials. The screening trials showed that the surface tension increased after precipitation with both PAX-XL60and PGA which leads to the assessment that the concentration of surface-active substances has decreased.Precipiation- and aeration trials in big lab-scale were performed at pH 7,5 and the optimal dosage of PAX-XL60. ForPGA, the precipitation and aeration trials were performed at pH 6 and the lowest dosage of the screening trials. Theaeration trials showed that precipitated CTMP-wastewater could be aerated more energy efficient than the samewastewater without precipitation.Calculations showed that energy costs can be reduced by nearly 90% by using the tested precipitation chemical PAXXL60respectively nearly 65% by using the tested precipitation chemical PGA according to the lab-scale trials. Thecosts for the chemicals are not included.