Abstract This thesis aims to increase our knowledge about the characteristics of chemical pulp process and wastewaters and how problematic substances, e.g. wood extractives, could be removed effectively and selectively by coagulation–flocculation with either internal or external water treatment. Characterization was performed by investigating kraft pulp bleaching filtrates, as well as wastewater, before (influent) and after (effluent) the activated sludge treatment by means of a range of chemical analyses and by carrying out size fractionation studies. Cationic polyelectrolytes were used to purify oxygen stage bleaching filtrate, and charge analyses (zeta potential, charge quantity) were carried out in order to understand the coagulation phenomenon. In activated sludge treatment, the enhancement of particle removal, either by filtration or using a chemical in the primary clarifier, would lead to savings in aeration costs and result in a more stable process. Microfiltration already with a large pore size (8 µm) removed 30–50% of the wood extractives from the influent. Separate treatment stages for certain wastewater fractions, e.g. debarking plant effluent, would ensure cost-efficiency. After the activated sludge process, the wood extractives were present as particles (18%) and < 3 kDa fraction (82%). β-sitosterol occurred only in particles in the effluent. The release of harmful components into the environment could be decreased by microfiltration (e.g. 0.45 µm) of the final effluent or using a chemical in the secondary clarifier. Interestingly a huge increase in BOD was realized in the 3 kDa fraction of both influent and effluent, which indicated the presence of toxic substances in the larger fractions. After passing the effluent into the water system, there might be a similar jump in the BOD because the effluent is diluted many-fold. This would contribute to the formation of areas with an oxygen deficit. In the coagulation–flocculation studies, effective and selective removal of wood extractives (92%) from the oxygen stage filtrate was obtained with a cationic polyelectrolyte of medium molecular weight and medium charge density at 72 °C and pH 5–6. The multimodal zeta potential distribution gave more information than the average zeta potential. Aggregation of colloidal particles occurred when only one zeta potential was observed. The number of different zeta potentials diminished with decreasing pH and after exceeding a certain polyelectrolyte dosage level.

Electrospinning is a fiber production method that has gained a special attention due to the simple setup and potential for the industry scale up to produce nanoregime polymer fibers. However, electrospun fibers have relatively poor mechanical properties, which could be improved by introducing reinforcing agents. Cellulose nanocrystals (CNCs) are a promising candidate for use as such fiber reinforcing phase due to nanoscale dimensions, excellent mechanical properties, abundance in nature, biocompatibility and renewability. The mechanical properties of reinforced fibers can be further improved by aligning them uniaxially. There are several reports available on aligning electrospun fibers and reinforcing them with CNCs. However, alignment of the reinforcing phase, such as CNCs, inside matrix is not studied extensively. The importance of aligning arises from different mechanical properties exhibited by the CNCs in longitudinal and transverse directions due to the high aspect ratio. This anisotropic nature of CNCs could be employed in nanocomposite fibers by aligning crystals along the fiber direction. In this study, the effect of the electric field modification on the alignment of CNCs in poly(vinyl) alcohol fibers was investigated. Fibers were collected using four different collector types, which also gave four different electric field configurations. Alignment of the reinforcing crystals in fibers with different degree of macroscopic orientation was studied using 2D XRD and polarized FT-IR. These studies confirm the alignment of both CNCs and PVA in uniaxially aligned fibers. Mechanical testing showed that improvement in alignment is directly related to the increase of the strength of the material. Aligned PVA-CNCs fibers had more than 100 times higher elastic modulus compared to non-aligned fibers. The rule of mixtures, Halpin-Tsai equation and orientation modified Cox’s equation were used to calculate theoretical values of elastic modulus and compare with experimental values. The comparison of between experimentally observed alignment of CNCs and theoretically predicted values shows that there is a potential for further improvement. The demonstrated improvements in the alignment of reinforcing phase could find applications, where well-aligned architectures are required, for example in uses as tissue engineering, scaffolds, membranes, microelectronic devices etc.

Abstract The dentin-pulp complex comprises mineralized dentin and the vital soft tissues encased inside dentin, i.e. odontoblasts and pulp tissue. During caries progression, the dentinal minerals are dissolved and eventually the collagenous organic matrix is degraded. However, the exact mechanisms and enzymes responsible for the organic matrix breakdown remain unknown. Matrix metalloproteinases (MMPs), a family of endopeptidases capable of degrading in concert virtually all extracellular matrix components, are expressed during normal dentin-pulp complex formation and maintenance. MMP activity has also been suggested to contribute to the organic matrix degradation during dentin caries progression and to the repair and defense reactions elicited by caries in the dentin-pulp complex cells. The aim of the study was to further elucidate the role of host MMPs in dentin caries progression and the origin of MMPs in carious dentin as well as the possible changes in MMP expression in the cells of the dentin-pulp complex in response to caries. MMP inhibitors decreased the area of dentin caries lesions in vivo, suggesting the involvement of host MMPs in dentin caries pathogenesis. When the overall MMP gene expression was examined by cDNA microarray, pooled pulp samples demonstrated a high level of MMP-13 expression, but failed to show any unequivocal changes in MMP expression due to caries. MMP-13 expression is rare among normal human adult tissues. Real-time quantitative PCR of individual pulp and odontoblast samples demonstrated a rather large variation in relative MMP-13 mRNA expression between samples, especially pulp samples. Protein expression of MMP-13 was detected in pulp and odontoblasts without any major differences between the tissues of sound and carious teeth. This was also the case with the MMP-20 (enamelysin) protein, which was demonstrated in odontoblasts and the pulp tissue of fully developed human teeth. MMP-20, MMP-8, and gelatinases (especially MMP-2) were demonstrated in human dentin, and dentinal MMPs exhibited activity against native and denatured type I collagen when released. The study demonstrates the presence of MMPs in the soft and hard tissue compartments of the dentin-pulp complex. These enzymes may also contribute to dentin caries progression and response reactions to caries.

Abstract The objective of this thesis was to determine the effects of design, operational and furnish quality parameters on pressure screen and hydrocyclone performance. The general contradictory interrelationships between capacity and selectivity in pressure screening and cleaning are commonly recognized, but deep understanding of the effects of design, operational and furnish quality parameters on the state of operation is missing. As separation selectivity is closely dependent on thickening and pulp passage, an operation curve for separation was applied and its application further developed to examine the parameters affecting pressure screen and hydrocyclone separation. New information was found on the geometry of the screen plate, furnish quality parameters in pressure screen fibre fractionation, and the hydrocyclone separation of fibres, sand and gases. The capacity increases achieved by changes in the wire screen plate geometry were found to be achieved at the cost of separation selectivity in probability screening. The capacity of the screen plate was affected by the flow on the screen plate and through it. The hydraulic resistance both in the forward and reverse flow directions was found to be of great importance for the capacity of the screen plate. Previously unreported knowledge was found regarding the effects of wire width, height and shape. Pressure screening capacity was found to decrease with increasing fibre length, fibre network strength and flocculation. Pressure screen fibre fractionation selectivity was increased by broadening of the fibre length distribution of the feed furnish. The furnish properties also affected the separation selectivity of fibres, sand and gases in the hydrocyclone. An increase in fibre network strength reduced the separation selectivity of the hydrocyclone separation of fibres and sand. Any increase in the specific surface area, and especially in the amount of fines, was found to make gas removal more challenging. It was concluded that a broader range of the specific surface distribution can increase the selectivity of fibre fractionation in the hydrocyclone. Knowledge of the general effects of design, operational and furnish quality parameters on the performance of pressure screen and hydrocyclone separation was deepened as a result of this work, which provides a framework for studying these effects further in pursuit of the general objective of maximizing capacity and selectivity while minimizing energy and investment costs.

Abstract Stickies refer to tacky contaminants in recovered paper, excluding wood extractives. Stickies originate from adhesives, ink binders and coating binders. Stickies able to pass a sieve of 100 or 150 μm (depending on standard) are called micro stickies, whereas the particles retained on the screen are called macro stickies. Dissolved and colloidal stickies are called secondary stickies. There are standard methods for macro stickies, but a standard method measuring the total amount of stickies is lacking. Furthermore, the size distribution, and nature of stickies in the sense if they are free particles or agglomerated with some other substances, has not been previously known. The information on the removal of stickies in different unit operations was also not known very well except for macro stickies. The aim of this thesis was thus to develop an analysis method for the total amount of stickies, determine the size distribution and nature of stickies, and find ways to better remove stickies in the deinking process. Extraction with tetrahydrofuran (THF) and High Pressure Liquid Chromatography (HPLC) with Size Exclusion Column (SEC) was used here to separate hydrophobic polymers (stickies) from the pulp suspension. An Evaporating solvent Light Scattering (ELS) detector was utilized to quantify the polymers after SEC. This analysis procedure was used in this thesis to measure stickies. Fractionation of pulp before the analysis was carried out if information of different-sized stickies was desired. The majority of stickies are micro stickies. A significant, although lower, portion of stickies are macrostickies, especially in the beginning of the deinking process. The dissolved and colloidal phase was found to contain wood extractives, and only trace amounts of stickies. Flotation is very effective in stickies removal. Ink and micro stickies were removed nearly equally in flotation, because they both are hydrophobic and are both in an optimal size range for removal in flotation. Ink measurements may be used for estimating the trends of stickies removal in flotation. The stickies removal in flotation may be enhanced by optimizing the pulper chemistry.

Abstract Bleaching is an essential process in chemical pulp production for better pulp brightness and longer life expectancy. However, it causes costs such as chemicals, energy, equipment, and loss of yield. Non-linear reactions and several process variables, with interactions, make large plants complicated to model and optimize. As an expensive process bleaching has been a natural target of optimization, but there is still the need to either improve these methods or consider the optimization problem from a new point of view. The aim of this thesis was to develop production optimization methods for pulp bleaching, so that they are practical, usable on-line, easy to tune, and transferable. According to our assumption, neural networks could provide a practical optimization method by combining analytical knowledge with real data. In this kind of problem, the load sharing concept, recognizing interactions in chemical usage and the serial multi-stage nature of the process can simplify the task. The related work in bleaching optimization was studied as well as multi-stage serial process solving in principle, related optimization methods and especially neural networks in optimization. The data were collected during normal mill operation and modeled using neural networks. Optimization was performed based on visualizing the neural network models. The results showed that backpropagation neural networks are capable of modeling parts of the bleach plant and also the entire bleaching operation to such an extent that they are useful in the optimization. The modeling and the tuning can be performed without a profound knowledge of the system, but the process is slower and less reliable. Moving a trained neural network to another mill is inadvisable. It is more reasonable just to transfer the knowledge of variables and network structure. The important factor in on-line production optimization is the stabilization of the disturbances and a well-controlled operation towards a more economical state. Generally, more than half of the total chemicals should be used in the first bleaching stage D0 and the remaining load should be divided so that the dosage at the D1 is about 30% higher than in the D2 stage.

Abstract The thesis clearly demonstrates that photon migration measurements allow characterization of pulp and paper properties, especially the fines and filler content of pulp, and the basis weight, thickness and porosity of paper. Pulp and paper are materials with a worldwide significance. Their properties strongly depend on the manufacturing process used. For efficient process control, the employed monitoring and measuring has to be fast. Therefore it is worthwhile to try to develop new approaches and techniques for such measurements. Recent advancements in optics offer new possibilities for such development. If two samples have different optical properties their photon migration distributions are different. The measurement of a photon migration distribution allows some features between two optically slightly dissimilar samples to be distinguished. Some simple measurements, which only yielded the photons' average time of flight, were made with an oscilloscope and a time-of-flight lidar. More precise measurements yielding photon pathway distribution or some selected characteristics like light pulse rise time, broadening, or fall time were measured with a streak camera. Two methods to assess photon path length distribution were introduced: particle determination with simulation, and streak camera with deconvolution. The basic properties for pulp are consistency and fines content and for paper the basic properties are thickness, basis weight and porosity. The influence on photon migration caused by changes in these basic properties was determined. As pulp and paper are rarely very basic, an additional property was demonstrated for both materials. For pulp it was the content of filler talc, and for paper it was the use of beaten pulp as a raw material. These additional properties were also distinguishable.

Ces dernières années, des thérapies à base de cellules mésenchymateuses ont été développées pour améliorer les thérapies qui visent à réparer l'homme et notamment la pulpe dentaire. Dans ce contexte, la dent apparait comme la source de cellules mésenchymateuses, souches ou progénitrices, permettant de réparer la pulpe dentaire. En effet, la pulpe dentaire est facile d'accès et les cellules pulpaires présentent un fort potentiel de différenciation. Actuellement, les différents organismes de contrôle recommandent d'utiliser des procédures standardisées pour l'isolement, le stockage et l'expansion des cellules en culture pour garantir une sécurité et une reproductibilité optimale lorsque les cellules sont utilisées en culture cellulaire. Cependant, la plupart des procédures utilisées pour la production de cellules à partir de la pulpe dentaire ne sont pas entièrement satisfaisante, car elles peuvent altérer les propriétés biologiques et la qualité des cellules. En effet, les procédures d'isolement cellulaire, d'enrichissement, de cryopréservation et d'amplification pendant de nombreux passages dans des milieux contenant des produits d'origine animale ou humaine sont connues pour affecter le phénotype des cellules, la viabilité, la prolifération et les capacités de différenciation. Ce travail de thèse s'intéresse à compiler les stratégies actuelles de fabrication de produits cellulaires à partir de la pulpe dentaire, puis il propose de nouveaux protocoles pour améliorer l'efficacité, la reproductibilité et la sécurité de ces nouvelles stratégies thérapeutiques. Ainsi nous avons isolé, amplifié et cryopréservé des cellules de la pulpe dentaire. Grace à un travail d'immunophénotypage, nous avons pu étudier différentes souspopulations à l'intérieur de la population totale. Enfin nous avons montré que ces cellules sont capables de rester congelées pendant plus de 500 jours sans présenter d'anomalies du caryotype et de conserver un potentiel de différenciation ostéo/odontogénique / Dental research currently explores the potential of cell-based products and tissue engineering protocols to be used as alternatives to usual pulp/dentin and bone therapies. In this context, stem/progenitor cells appear to be particularly appropriate because of their high expansion ability and differentiation potential both in vitro and in vivo. If bone marrow and adipose tissue are considered potential sources of stem/progenitor cells, painful collection protocols, the decline of the amount of stem/ progenitor cells with age, the necessity of general anesthesia, reduced proliferation capacity, and risk of morbidity at the collection site encourage the search for alternative candidates. Human impacted third molars are frequently removed for therapeutic reasons and the loose connective tissue they contain, the dental pulp, appears to be a valuable source of stem/progenitor cells for pulp/dentin and bone engineering. Indeed, it contains various cell populations that exhibit osteo/odontoblastic differentiation capabilities and that can be cryopreserved for periods of time greater than 6 months. Interestingly, human dental pulp cell (HDPC) populations were recently successfully used for regenerating human pulp/dentin and bone. Cell-based products for tissue engineering are now referred to as human cellular tissue-based products or advanced therapy medicinal products, and guidelines from the American Code of Federal Regulation of the Food and Drug Administration (21 CFR Part 1271) and the European Medicines Agency (European Directive 1394/2007) define requirements for appropriate cell production. These ‘‘good manufacturing practices’’ include recommendations regarding laboratory cell culture procedures to ensure optimal reproducibility, efficacy, and safety of the final medicinal product

The career path of African American novelist Chester Himes is often characterised as a u-turn. Himes grew to recognition in the 1940s as a writer of the Popular Front, and a pioneer of the era's black 'protest' fiction. However, after falling out of domestic favour in the early 1950s, Himes emigrated to Paris, where he would go on to publish eight Harlem-set detective novels (1957-1969) for Gallimard's La Série Noire. Himes's 'black' noir fiction brought him critical and commercial success amongst a white European readership, and would later gain a cult status amongst an African American readership in the late 1960s and early 1970s. Himes's post-'protest' career has been variously characterised as a commercialist 'selling out'; an embracing of black 'folk' populism; and an encounter with Black Atlantic modernism. This thesis analyses the Harlem Cycle novels in relation to Himes's career, and wider debates regarding postwar African American literature and race relations.Fundamentally, I argue that a move into commercial formula fiction did not curtail Himes's critical interest in issues of power, exploitation, and racial inequality. Rather, it refocused his literary 'protest' to representational politics itself, and popular culture's ability to inscribe racial identity, resistance and exploitation. On the one hand, Himes's Harlem fiction meets a formulaic and commercial demand for images of 'pathological' black urban criminality. However, Himes, operating 'behind enemy lines', uses the texts to dramatise this very dynamic. Himes's pulp novels depict a heightened Harlem that is thematically 'pulped' by a logic of capitalist exploitation, and a fetishistic dominant of racial difference. In doing so, Himes's formula fiction makes visible certain anti-progressive shifts in the analysis and representation of postwar race relations. My methodology mirrors the multiple operations of the texts, placing Himes's detective fiction in relation to a diverse and interdisciplinary range of sources: literary, historical, and theoretical. Using archival material, I look in detail at Himes's public image and contemporary reception as a Série Noire writer, his professional correspondence with French and U.S. literary agents, and his private thoughts and later reflections regarding his career. This methodology attempts to get to grips with a literary triangulation between Himes's progressive authorial intentions, the demands placed upon him as a Série Noire writer, and the wider ideological shifts of the postwar era. By exploring these different historical, geographical and literary contexts, this thesis offers a wide-reaching analysis of how cultural and racial meanings are produced and negotiated within a commodity form.

The state of Uttar Pradesh occupies about 9 per cent of the total geographical area of India, supports more than 16 per cent of its 440 million people, but has less than 6 per cent of the Indian forests. It is, in many ways, an underdeveloped part of a developing nation. There is a great potential for contributions of Uttar Pradesh to the economic development of India, by the expansion of the U. P. pulp and paper industry. Per capita consumption of paper and paper-board in India is expected to increase from about 1.3 Kg in 1965 to 6.2 Kg in 2000. If the production in the country increases as anticipated in this thesis, and if more raw materials are not made available, shortages of both long-fibred and short-fibred raw materials will begin to be felt strongly by about 1975 and will progressively increase. To reduce these shortages the Uttar Pradesh Forest Department is establishing plantations of fast-growing tree species. The Mysore hybrid eucalypt is being planted to provide short-fibred pulpwood and plantations of the bamboo (D endrocalamus strict us) will yield long-fibred pulp. Present plans of the U. P. Forestry Department have not paid enough attention to growing long-fibred material. The Department should concentrate mainly on the production of long-fibred material because much short-fibred material is available as sugar cane bagasse in the U. P. It also could be secured when needed if eucalypt and poplar plantings were made by farmers. Eucalypts, pines, poplars and bamboos have been discussed regarding their suitability for production of pulpwood in the forest areas of U. P. Greatest attention has been given here to eucalypts but it is concluded that pines and bamboos are the most desirable. The need for producing within India all of the pulp and paper required domestically has been considered more important than that for supplying paper and paper-board to Indian consumers at world prices. At present It appears as if the foreign exchange conserved by reducing pulp and paper imports can be more usefully spent in buying machinery, fertilizers, and technical knowledge. India can become self-sufficient in its paper and paper-board needs after 1980 only if enough long-fibred raw materials are produced. Therefore, major trials of potentially suitable, fast-growing, long-fibred species should be established soon. The paper industry in U. P. should continually strive to improve its technology and bring down its costs of production because in the long run it will have to become competitive in world markets. The U. P. Forest Department should not judge its efficiency solely by the size of net surplus created in a plantation program. It should also consider the potential contributions of its plantations in the growth of Indian industry and improvement of real national income. Intensive economic analyses of the problems discussed here should be undertaken to refine objectives for the long-term development of U. P.'s forest industry. / Forestry, Faculty of / Graduate