Dynamic wetting and absorption of water droplets on heterogeneous surfaces, including paper, was studied. The objective was to elucidate the role of surface heterogeneities on wetting and absorption properties of paper. To better understand the phenomena, wetting on glass slides with a controlled level of heterogeneity was investigated. Also, partially hydrophobized glass capillaries were used to simulate capillary penetration into the pores on sized paper. / Dynamic wetting on paper followed a power law model with a lower rate than wetting on a smooth surface. The chemical composition of the paper surface did not affect the wetting dynamics, which was mainly affected by surface roughness in a micron scale. The super-hydrophobic properties of the sized papers were due to air entrapment in the micron-scale roughness on the surface. / Wetting and absorption of water droplets on sized paper occurred in different time scales. A pseudo-equilibrium contact angle was reached at the end of wetting just before absorption of water droplets. Increasing the surface coverage of the hydrophobic domains on paper by sizing increased the pseudo-equilibrium contact angle and delayed absorption into paper. This delay was related to partial dissolution of the surface sizing polymers in the water droplets on the surface. / The equilibrium contact angle of water droplets on partially hydrophobized glass slides was a linear function of a characteristic dimension of the hydrophobic domains and the length of the three phase contact line. / The dynamic rise of water in partially hydrophobized vertical capillaries followed two mechanisms. First, capillary rise was a function of the dynamic contact angle, changing with the velocity of the contact line. Second, local changes of the advancing contact angle due to the heterogeneities on the capillary walls lowered the capillary rise velocity. The stick (pause) and jump of the contact line was another effect of the hydrophobic domains. Capillary rise dynamics was a function of the advancing contact angle of water droplets measured on a flat glass slide with the same coverage of hydrophobic domains.

On a papermaking machine, fines and colloids are retained in a paper sheet. The most important particle interactions are among particles having a high weight fraction and a short characteristic interaction time. Most of these interactions follow Langmuir kinetics, in which the flocculation efficiency is one of the important parameters. To enhance retention, many retention aids are available, one of which is neutral polyethylene oxide (PEO) used in combination of a phenolic cofactor (CF). / In this work, a new model was derived in which all possible interactions were considered and assumed to follow Langmuir kinetics. Since fines are the main component in the headbox of mechanical grade furnishes, fines homo- and heteroflocculation with a PEO/CF retention aid were investigated in a circulating flow loop, and found to follow Langmuir kinetics. The small amount of fines deposited on the fibers was attributed to the large detachment rate in turbulent shear. The apparent difference in the deposition time and the half time of flocculation was attributed to difference in efficiency. Fines homoflocculation showed that fines are flocculated (without a retention aid) to various extents depending on shear, and that aggregates of flocs will form when a retention aid is added. / The PEO/CF flocculation efficiency was found to be a function of various parameters, i.e., aging of PEO solution, stirring intensity and time of stirring during dissolution, concentration at storage, shearing and dilution prior to injection. Optimum conditions were found for most parameters, and a critical shear intensity was determined. This PEO behavior was attributed to the extent of entanglements of PEO coils, which can be characterized prior to its addition to the flocculation vessel by a newly developed method. In this method, the pressure drop of a PEO solution passing through a capillary constriction was measured and correlated with its flocculation efficiency. Using the derived correlation, the flocculation efficiency can be estimated, and the relevant parameters can be controlled. Moreover, the salt effect on a PEO/CF system in a pulp was investigated. Salt was found to react with a CF causing a decrease in the flocculation efficiency. The effect of this reaction can be eliminated if PEO is added directly after CF addition.

Certain types of dead, inactive biomass can very effectively immobilize and concentrate heavy metals. In this work, a (bio-)sorption process has been studied using the biomass of waste crab shells which is particularly suited for extracting anionic metal species such as gold-cyanide, chromate and vanadate. These metal species are much difficult to remove from solutions. / The current work demonstrated the crab-shell biosorbent potential. Acid Washed Ucides cordatus Shells (AWUS) removed more metal than other excellent biosorbents such as Bacillus (bacterium), Penicillium (fungus) or Sargassum (alga), with metal uptakes up to 0.79 mmol V/g dry AWUS, 0.54 mmol Cr/g, and 0.17 mmol Au/g. The bound metals could easily be eluted from the biosorbent (AWUS) by a simple alkali wash. Repeating 3 adsorption-desorption cycles without performance deterioration indicated the reusability of the biosorbent. / The mechanism of anion biosorption was confirmed to be adsorption by electrostatic attraction. FTIR analyses indicated amide groups as the key sites for metal anion binding. They are particularly effective at low pH when they become fully protonated. The anionic metal speciation in the solution also played important role affecting the anion uptakes. / Biosorption study in the V-Cr binary system established that the presence of vanadate greatly depressed the Cr uptakes, however, vanadate uptake was not interfered by chromate. / The developed one-site anionic metal species adsorption equilibrium model, considering the non-ideality in the liquid phase and the interference of Cl -, agreed reasonably well with the anion adsorption by AWUS as a function of solution pH and ionic strength. Multi-metal equilibrium adsorption models extended from the Langmuir model effectively described the metal interference behaviour.

The liquid-liquid extraction of biomolecules using a reverse micellar system has been studied in literature as a simple and easily scalable purification method that can be used in fermentation industry. The recovery of proteins from the reverse micellar phase has shown a low efficiency (less than 20%) making the technique unfavorable in industrial practice. In addition, the modeling is often complicated due to the complex interactions among surfactants, cosurfactants, electrolytes and charged biomolecules. Thus, this work was aimed to examine the solubilization behavior of lysozyme into four different reverse micellar systems, in order to better understand the extraction mechanism. The water uptake and the concentration of lysozyme obtained in the organic phase were measured. The recovery of lysozyme from the reverse micellar phase was attempted using a second aqueous phase with pH and ion strength adjustments, a conventional method used in literature. The best extraction was obtained with aerosol-OT, but low recoveries were obtained with all three anionic and one cationic surfactants tested. During these experiments, the formation of a white precipitate at the aqueous-organic interface was observed, and this observation provided the basis for an understanding of the extraction mechanism and a proposal of a novel separation method. / A novel purification method is proposed to extract lysozyme from an aqueous solution using surfactants and recover it as a solid. In this method, the surfactant is directly added to the aqueous solution containing lysozyme, instead of using a liquid-liquid extraction mechanism. Upon contact, the lysozyme forms an insoluble lysozyme-ligand complex. The insoluble compound was then dissolved in acetone, and the surfactant-free lysozyme was recovered as a solid. An overall recovery efficiency of up to 70% was obtained, and the lysozyme was found to retain its original enzymatic activity. A simple mathematical model is suggested to describe the formation of lysozyme-surfactant complex. The model was also used to better understand, the extraction mechanism of lysozyme into a reverse micellar phase.

In polymer extrusion, a melt instability called gross melt fracture is often observed when the extrusion rate is increased beyond a critical value. Because gross melt fracture limits the production rate, much attention has been devoted to predicting when it will occur. However, there is still no general understanding of the origin of this phenomenon. Several criteria have been proposed for the onset of gross melt fracture (OGMF), but these depend on the procedure used for measuring them and thus are not material properties. The use of a critical extensional stress (CES) is proposed here as a criterion for OGMF. This stress is estimated using the entrance pressure drop analyses proposed by Cogswell and by Binding. / Orifice dies were used to eliminate the complication arising from the presence of a capillary. The entrance angle and contraction ratio were varied to study the effect of die geometry. Various materials including conventional linear low and high density polyethylene and new polyethylenes produced by metallocene and constrained geometry catalysts were used in a study of the effect of molecular structure on OGMF. The latter materials are of special interest, because they have very well-defined molecular structure in terms of molecular weight (MW), molecular weight distribution (MWD), and long chain branching (LCB). In addition, the effect of particulate additives (boron nitride and carbon black) was investigated. / It was found that CES is independent of the die, contraction ratio, and entrance angle, as long as the angle is equal to or greater than 90 degrees. This result suggests that CES is, indeed, a material property. The CES was found to be independent of additive content up to a level of 0.5 wt%. Further, it was found that while CES is independent of MW, increasing levels of LCB and broadening MWD increase CES. Finally, brittle fracture at the entrance of the die is proposed as the cause of gross melt fracture.

Model materials with discretely varying loss factors under microwave fields, were studied with respect to drying characteristics. In the first part numerical simulations were conducted to study the fluid flow and heat transfer in a rectangular microwave cavity where cylindrical samples were heated by microwave. The Reynolds numbers studied in this work were 2800, 5600 and 11200 based on the entrance diameter to the rectangular microwave cavity. Heat transfer results in terms of Nusselt numbers for the Reynolds number ranges studied are presented and discussed. / In the second part of the study a mathematical model was developed to describe heat and mass transfer of a model material under microwave fields. The dynamic temperature and moisture profiles of cylindrical composite samples subjected to microwave and convective energy were determined and validated at microwave power density levels of 0.20 W/g, 0.3 W/g and 0.4 W/g based on initial weight of the sample. Model results were compared with experimental data and found to agree within 1.0--2.6%. Predicted temperature profiles at selected locations within the model material were also showed a good agreement with experimental data. However, a significant discrepancy between the numerical and experimental temperature results occurred after t > 30 minutes. This might have been due to localized overheating, or to mathematical model overestimation. / Lastly, a quality evaluation of the dried samples was also performed. Quality attributes evaluated were surface color, shrinkage and rehydration capacity. Samples dried as a special case of biological material were of better quality when compared to other samples.

Orthopaedic tissues such as bone, cartilage, ligament, tendon and muscle serve primarily mechanical roles in support of controlled movement. These tissues must continually adapt to changes in their physical environments, in a lifelong process termed remodelling. Interactions between cells in orthopaedic tissues and their physical surroundings underlie tissue functions, remodelling, responses to injury, diseases and repair. Osteoclasts are a type of bone cell responsible for bone resorption. Effects of mechanical stimulation on osteoclast differentiation and subsequent bone resorption activity are of interest for understanding bone physiology within a mechanically active environment. As a preliminary step toward osteoclast mechanotransduction experiments, we optimized conditions for osteoclast differentiation and adhesion to a highly extendable substrate made of poly(dimethylsiloxane) (PDMS). Results showed that a covalently-bound collagen coating can be used to promote osteoclast differentiation on extendable PDMS substrates which enables studies of osteoclast mechanostimulation. Differentiated osteoclasts maintained their functionality as evidenced by actin ring formation, gene expression and bone resorbing ability as specific features of active osteoclasts. To then study osteoclast behaviour in the context of mechanical stimulation, we applied relatively low frequency stimuli to osteoclast precursors and examined osteoclast differentiation and functionality. It was shown that low frequency mechanical stimulation can enhance osteoclastogenesis, in contrast with higher frequency stimulation which is known to be inhibitory during differentiation. Conditioned medium collected from mechanically stimulated cells contained factors that support differentiation of osteoclast precursors to mature osteoclasts. Results also indicated that the ERK 1/2 signaling pathway participates actively in the differentiation of bone marrow cells to osteoclasts under low frequency mechanical stimulation. Mechanotransduction is also a ubiquitous regulator of cell behaviour in articular cartilage. In particular, fluid and solute transport in compressed cartilage regulate cell metabolism and may provide means for minimally invasive detection of tissue degeneration. We studied effects of static compression on diffusion of different contrast agents applicable in magnetic resonance (MR) or X-ray computed tomography (CT) through articular cartilage. Static compression occurs physiologically and results in changes in extracellular matrix (ECM) density, and here provided a means for nondestructive modification of tissue structure. Consistent with previous reports, diffusivity of contrast agents tended to decrease with increasing static compression. Alterations in fluid and GAG contents of cartilage ECM were consistent with this behaviour. Findings suggest that measurement of contrast agent diffusivities during CT or MR imaging could be used to assess focal changes in matrix properties in articular cartilage. / Les tissus orthopédiques tels que les os, les cartilages, les ligaments, les tendons et les muscles jouent des rôles essentiellement mécaniques en support au mouvement contrôlé. Ces tissus doivent continuellement s'adapter aux changements dans leur environnement, dans un processus continu appelé remodelage. Les interactions entre cellules dans les tissus orthopédiques et leur environnement physique sont à la base des fonctions des tissus, les réponses aux blessures, les maladies, le remodelage, et la réparation.Les ostéoclastes sont une categorie de cellule osseuse responsable de la résorption osseuse. Les effets de la stimulation mécanique sur la différenciation des ostéoclastes et l'activité subséquente de résorption osseuse sont intéressants pour la compréhension de la physiologie osseuse dans un environnement mécaniquement active. Dans un premier temps vers des expériences de mécanotransduction des ostéoclastes, nous avons optimisé les conditions de la différenciation des ostéoclastes et de l'adhérence à un substrat hautement extensible en poly (diméthyl) (PDMS). Les résultats démontre qu'un revêtement de collagène lié de façon covalente peut être utilisé pour promouvoir la différenciation des ostéoclastes sur des substrats PDMS extensible qui permet des études de mechanostimulation des ostéoclastes. Les ostéoclastes différenciés ont maintenu leur fonctionnalité comme en témoigne la formation d'anneau d'actin, l'expression des gènes et la capacité de résorption osseuse en tant que caractéristiques spécifiques des ostéoclastes actifs. Pour ensuite étudier le comportement des ostéoclastes dans le cadre de la stimulation mécanique, nous avons appliqué des stimuli à relativement basse fréquence à des précurseurs des ostéoclastes et examiné la différenciation et fonctionnalité des ostéoclastes. Il a été montré que la stimulation mécanique à basse fréquence peut améliorer ostéoclastogenèse, en contraste avec la stimulation haute fréquence qui est connu pour être l'inhibiteur de la différenciation. Des milieux conditiotrned recueillies à partir de cellules stimulées mécaniquement contenait des facteurs qui soutiennent la différenciation des précurseurs des ostéoclastes en ostéoclastes matures. Les résultats ont également indiqué que la 1/2 voie de signalisation ERK participe activement à la différenciation des cellules de la moelle osseuse à ostéoclastes sous stimulation mécanique à basse fréquence. Mécanotransduction est également un régulateur ubiquitaire du comportement des cellules dans le cartilage articulaire. En particulier, le transport des fluides et de solutés dans le cartilage comprimé régule le métabolisme des cellules et peut prévoir des moyens de détection minimalement invasif de la dégénérescence des tissus. Nous avons étudié les effets de la compression statique sur la diffusion des différents agents de contraste applicables à la résonance magnétique (IRM) ou le x-ray tomodensitométrie (TDM) à travers le cartilage articulaire. La compression statique survient physiologiquement et entraîne des changements dans la matrice extracellulaire (ECM) de densité, et ici a fourni un moyen de modification non destructive de la structure des tissus. En accord avec les rapports précédents, la diffusivité d'agents de contraste à tendance à se diminuer avec l'augmentation de la compression statique. Les modifications dans le liquide et dans le contenu de gag du cartilage ECM étaient compatibles avec ce comportement. Les résultats suggèrent que la mesure de contraste de diffusivités des agents durant l'imagerie CT ou IRM pourrait être utilisée pour évaluer les changements correspondants dans les propriétés matrice du cartilage articulaire.

This thesis examines aspects of solute partitioning and diffusion in articular cartilage and solute adsorption to its surfaces, and discusses their potential applications in functional assessment of cartilage. Investigation of temperature dependence of solute transport in cartilage showed general trends of increased partition coefficient and diffusivity with increasing temperature for a range of fluorescent solutes including fluorescein isothiocyanate, 4 and 40 kDa dextrans, myoglobin, insulin and chondroitin sulfate. Unexpected behaviours of some solutes and small but significant changes in water and glycosaminoglycan contents of explants underscored the importance of solute–matrix interactions. Examining solute adsorption onto cartilage surfaces revealed that ignoring adsorption effects results in measurements of apparent partition coefficients (Ka) significantly greater than actual ones (K). The differences between Ka and K increased with increasing explant surface-to-volume ratio. Solutes studied included 3 or 4 kDa and 40 kDa dextrans, chondroitin sulfate, insulin and myoglobin labeled with three different fluorophores and fluorophores alone. A theoretical model was also developed to predict the resulting errors in K measurements and to estimate K based on Ka data. Finally, solute adsorption onto cracked surfaces of mechanically injured and sliced cartilage explants was observed to be significantly lower than intact surfaces. Studied solutes included fluorescently labeled native dextran, dextrans modified with aldehyde groups or a chondroitin sulfate (CS)-binding peptide and the peptide alone. Adsorption at intact surfaces of injured and sliced explants was found to be less reversible than at surfaces of uninjured explants. Modification of dextrans with aldehyde groups or the peptide enhanced the adsorption with the same level of differential adsorption to cracked and intact surfaces. These findings indicate that solute adsorption to cartilage is sensitive to structural or biochemical changes at otherwise healthy-looking tissue surfaces which may be exploited as a potential mechanism for detection of focal injuries. / Cette thèse examine les aspects de la partitionnement et de la diffusion des solutés dans le cartilage articulaire ainsi que l'adsorption des solutés sur ses surfaces et discute leurs applications potentielles dans l'évaluation fonctionnelle du cartilage. Étude de la dépendance de la température de transport de soluté dans le cartilage a montré une tendance générale de l'augmentation du coefficient de partage et de la diffusivité à température croissante pour une gamme de solutés fluorescents y compris l'isothiocyanate de fluorescéine, 4 et 40 kDa dextranes, la myoglobine, l'insuline et du sulfate de chondroïtine. Comportements inattendus de certains solutés et des variations faibles mais significatives du contenu de l'eau et des glycosaminoglycanes dans les explants ont souligné l'importance des interactions soluté-matrice. L'examen de l'adsorption du soluté sur les surfaces de cartilage a révélé qu'ignorer les effets d'adsorption donne lieu à des mesures de coefficients de partage apparent (Ka) significativement plus grandes que celles réelles (K). Les différences entre Ka et K ont augmenté en augmentant le ratio de la surface sur volume des explants. Solutés étudiés comprenaient 3 ou 4 kDa et 40 kDa dextranes, sulfate de chondroïtine, l'insuline et la myoglobine conjugués avec trois fluorophores différents et des fluorophores seuls. Un modèle théorique a également été développé pour prédire les erreurs dans les mesures de K et d'estimer le K à partir des données de Ka. Enfin, l'adsorption de soluté à les fissures du cartilage blessé mécaniquement et tranché a été observée d'être significativement moins que les surfaces intactes. De plus, il a été trouvé que l'adsorption sur les surfaces intactes des explants blessés et tranchés était moins réversible que sur les surfaces des explants indemnes. Ces résultats suggèrent que l'adsorption de soluté sur les surfaces de cartilage peut être exploitée comme un mécanisme potentiel pour la détection des lésions de surface et aussi des changements structurels ou biochimiques au niveau des surfaces qui ressemblent visuellement sain. Les solutés étudiés ont été dextrane natif, dextranes modifiés par l'aldéhyde ou par un peptide de liaison de sulfate de chondroïtine (CS) et le peptide seul, tout conjugué avec les fluorophores. Modification de dextranes avec l'aldéhyde ou le peptide a amélioré l'adsorption avec le même niveau d'adsorption différentielle sur des surfaces fissurées et intactes.

Polymerized colloidal crystal arrays (PCCAs) are colloidal crystal arrays that are embedded in a hydrogel matrix. Because they exhibit iridescent colour that can change in response to external stimuli, they have potential to be useful sensing materials. In this research, a new testing platform was synthesized by immobilizing PCCAs on filter paper. This is possible because paper is a porous, hydrophilic, and compliant support. Two methods were developed to optimize these so-called paper-based PCCAs (PB-PCCAs, M. Li, M.Eng. thesis, McGill University). A two-step method involves crystallizing colloidal spheres on paper and then applying a hydrogel to fix the array. Here, the temperature, cast size, dispersion concentration, contact angle of the colloidal dispersion with the mould, and filter paper type all influence the crystallization quality. In a simpler one-step method, PB-PCCAs can be assembled by directly depositing colloidal spheres in pre-gel solution onto paper or gel-filled paper. The one-step method produces much more intense and uniform iridescent colour, and uses significantly less gel and nanoparticles. Both techniques have been optimized to produce superior colour and surface texture than achieved previously, thereby paving the way toward our ultimate goal of developing aptamer functionalized colloidal crystal arrays for molecular- and bio-sensing. / Polymérisés réseaux cristallins colloïdaux (PCCAs) sont des réseaux cristallins colloïdaux qui sont incorporés dans une matrice d'hydrogel. Parce qu'ils présentent une couleur irisée qui peut changer à cause des stimuli externes, ils ont le potentiel d'être utilisé en matériaux de détection. Dans le cadre de cette recherche, une plate-forme de test nouvelle a été synthétisée en immobilisant PCCAs sur un papier filtrant. Ceci est possible parce que le papier est un support poreux hydrophile, et flexible. Deux méthodes ont été développées afin d'optimiser ces soi-disant à base de papier PCCAs (PB-PCCAs, M. Li, M.Eng. Thèse, Université McGill). Procédé en deux étapes est la cristallisation des sphères colloïdales sur papier et puis la application de un hydrogel pour fixer la matrice. Ici, la température, la taille coulée, la concentration en dispersion, l'angle de contact de la dispersion colloïdale sur le moule, et le type de papier filtrant ont tout influence sur la qualité de cristallisation. Dans un simple procédé d'une seule étape, PB-PCCAs peut être assemblé en déposant les sphères colloïdales et le solution de pré-gel sur du papier ou du papier rempli de gel. Cette méthode produit beaucoup plus de couleur intense et uniforme, et utilise beaucoup moins de gel et de nanoparticules. Les deux techniques ont été optimisées pour produire des mieux couleurs et la mieux texture de surface. Cela nous aidera à développer aptamères fonctionnalisés réseaux cristallins colloïdaux pour la molécule de détection enfin.

Many pharmaceuticals, such as the antibiotic sulfamethoxazole, are not eliminated during a conventional wastewater treatment process and are often not biodegraded in the environment. In this project, 60 mg/L and 100 μg/L solutions of sulfamethoxazole in both reverse osmosis water and wastewater were treated with ozone. A solid phase extraction procedure with reproducible analyte recoveries was developed to pre-concentrate the low concentration of sulfamethoxazole in both water matrices (reverse osmosis and municipal wastewater). The wastewater matrix had no effect on the required ozone dose to reduce the concentration of sulfamethoxazole below the SPE-HPLC limit of detection. Solutions with an initial concentration of 60 mg/L required an ozone dose of 331 mg/L and eight peaks were detected throughout experiments. Solutions with an initial concentration of 100 μg/L required a dose of 55 mg/L and only four peaks were detected. Analysis of the degradation products showed that 4-aminobenzene sulfonamide, N-(3-phenylpropyl)-acetamide, 2-methyl-benzoxazole and phenol were present in both high and low concentration samples. In addition, methanol, ethanol, acetic acid, methyl acetate and ethyl acetate were present in the high concentration samples. / Plusieurs pharmaceutiques, tel que l’antibiotique sulfaméthoxazole ne sont pas totalement éliminées lors du traitement des eaux usées et ne sont pas biodégradables dans l’environnent. Au cours de ce projet, deux types de solutions de sulfaméthoxazole ont été étudiées : à base d’eau traitée par osmose inverse et à base d’eau usée municipale. Des solutions ayant des concentrations de 60 mg/L et 100 μg/L ont été traitées par ozonation.Une méthode d’extraction en phase solide a été développée afin de préconcentrer les échantillons avant l’analyse par HPLC. Les solutions de sulfaméthoxazole composées d’eau traitée par osmose inverse et d’eau usée ont requis la même quantité d’ozone afin de réduire la concentration de sulfaméthoxazole sous la limite de détection du HPLC. Les solutions avec une concentration initiale de 60 mg/L ont requis une dose d’ozone de 331 mg/L et huit produits de dégradation ont été détectés. Les solutions ayant une concentration initiale de 100 μg/L ont requis une dose de 55 mg/L et seulement quatre produits de dégradation ont été détectés. L’analyse des produits de dégradation a démontré que le 4-aminobenzène sulfonamide, N-(3-phenylpropyl)-acetamide, 2-méthyl-benzoxaole et le phénol sont présents dans les solutions de faible et haute concentration initiale en sulfaméthoxazole. De plus, le méthanol, l’éthanol, l’acide acétique, l’acétate de méthyle et l’acétate d’éthyle sont ont été détectés dans les solutions de haute concentration.