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Fouling is a chronic problem in many heat transfer systems and results in the need for frequent heat exchanger (HEX) cleaning. In the dairy industry, the associated operating cost and environmental impact are substantial. Antifouling coatings are one mitigation option. In this work, the fouling behaviour of fluoropolymer, polypropylene and stainless steel heat transfer surfaces in processing raw milk and whey protein solution are studied. Methodologies to assess the economics of antifouling coatings are developed and applied. Two experimental apparatuses were designed and constructed to study fouling at surface temperatures around 90 °C. A microfluidic system with a 650 x 2000 µm flow channel enables fouling studies to be carried out by recirculating 2 l of raw milk. The apparatus operates in the laminar flow regime and the capability to probe the local composition of delicate fouling deposit $\textit{in-situ}$ with histological techniques employing confocal laser scanning microscopy. A larger bench-scale apparatus with a 10 x 42 mm flow channel was built to recirculate 17 l of solution in the turbulent flow regime which is more representative of conditions in an industrial plate HEX. Experimental results demonstrate that fluoropolymer coatings can reduce fouling masses from raw milk and whey protein solution by up to 50 %. Surface properties affect the structure and composition of the deposit. At the interface with apolar surfaces raw milk fouling layers are high in protein, whereas a strongly attached mineral-rich layer is present at the interface with steel. Whey protein deposits generated on apolar surfaces are more spongy and have a lower thermal conductivity and/or density than deposits on steel. The attraction of denatured protein towards apolar surfaces and the formation of a calcium phosphate layer on steel at later stages of fouling are explained with arguments based on the interfacial free energy of these materials in water. The financial attractiveness of coatings is considered for HEX subject to linearly and asymptotically increasing fouling resistance and using a spatially resolved fouling model. An explicit solution to the cleaning-scheduling problem is presented for the case of equal heat capacity flow rates in a counter-current HEX. Scenarios where the use of coatings may be attractive or where there is no financial benefit in cleaning a fouled exchanger are identified. Finally, experimental data are used to estimate the economic potential of fluoropolymer coated HEXs in the ultra-high-temperature treatment of milk. In the considered case, the value of a fluoropolymer coating inferred from the reduction in fouling is estimated to be around 2000 US$/m².

Reciprocating compressors are critical components for the natural gas energy infrastructure throughout the world. Proper lubrication of PTFE and PEEK based packings and piston rings (seals) in the compressor cylinder is necessary to prevent leaks of methane to the environment and allow efficient, reliable, and extended operation of the compressor. Cylinder lubrication is poorly understood and commonly cited as the reason for premature seal failures while being a major annual expense for compressor station operators. An industry priority is to reduce the amount of lubricant injected into the compressor cylinder. The lubricant is carried away by the process gas and collects in pipelines or other downstream equipment. To better understand the tribological aspects and physical phenomena of compressor cylinder lubrication, the effect of high pressure methane on the surface tension of common lubricants and sealing materials was investigated. Methane gas pressure exhibited an inverse relationship with liquid lubricant surface tension through a pendant drop test. Methane pressure also increased the contact angles of sessile drops of lubricants on the solid surfaces. Nitrogen pressure exhibited the same trends but to a lesser extent than methane. Analysis using the Owens, Wendt, Rabel and Kaelble calculation method revealed that as methane pressure increased, the surface free energy of the seal materials decreased. These results further revealed that increased gas pressure decreased the wettability of lubricants on the materials. PTFE based materials decreased much more than PEEK based materials. Spontaneous adsorption of the pressurized gases on the surface of the lubricant drops and sealing materials was determined to be the underlying cause of the reductions of surface energy. This new understanding is significant because it better explains the observed lubrication phenomena and may be able to guide the industry toward optimized lubrication, more efficient seal designs or better selection of lubricants and materials specifically suited for high pressure service.

Micronisation of active pharmaceutical ingredients (APIs) to achieve desirable quality attributes for formulation preparation and drug delivery remains a major challenge in the pharmaceutical sciences. It is therefore important that the relationships between crystal structure, the mechanical properties of powders and their subsequent influence on processing behaviour are well understood. The aim of this project was therefore to determine the relative importance of particle attributes including size, crystal quality and morphology on processing behaviour and the characteristics of micronised materials. It was then subsequently intended to link this behaviour back to crystal structure and the nature of molecular packing and intermolecular interactions within the crystal lattice enabling the identification of some generic rules which govern the quality of size reduced powders. In this regard, different sieve fractions of lactose monohydrate and crystal variants of ibuprofen and salbutamol sulphate (size, morphology and crystal quality) were investigated in order to determine those factors with greatest impact on post-micronisation measures of particle quality including particle size, degree of crystallinity and surface energy. The results showed that smaller sized feedstock should typically be used to achieve ultrafine powders with high crystallinity. This finding is attributed to the reduced number of fracture events necessary to reduce the size of the particles leading to decreases in milling residence time. However the frequency of crystal cracks is also important, with these imperfections being implicated in crack propagation and brittle fracture. Ibuprofen crystals with a greater number of cracks showed a greater propensity for comminution. Salbutamol sulphate with a high degree of crystal dislocations however gave highly energetic powders, with reduced degree of crystallinity owing to the role dislocations play in facilitating plastic deformation, minimising fragmentation and extending the residence of particles in the microniser. Throughout these studies, morphology was also shown to be critical, with needle like morphology giving increased propensity for size reduction for both ibuprofen and salbutamol sulphate, which is related to the small crack propagation length of these crystals. This behaviour is also attributed to differences in the relative facet areas for the different morphologies of particles, with associated alternative deformation behaviour and slip direction influencing the size reduction process. Molecular modelling demonstrated a general relationship between low energy slip planes, d-spacing and brittleness for a range of materials, with finer particle size distributions achieved for APIs with low value of highest d-spacings for identified slip planes. The highest d-spacing for any material can be readily determined by PXRD (powder x-ray diffraction) which can potentially be used to rank the milling behaviour of pharmaceutical materials and provides a rapid assessment tool to aid process and formulation design. These studies have shown that a range of crystal properties of feedstock can be controlled in order to provide micronised powders with desirable attributes. These include the size, morphology and the density of defects and dislocations in the crystals of the feedstock. Further studies are however required to identify strategies to ensure inter-batch consistency in these attributes following crystallisation of organic molecules.

The surface functionalisation of polyethylene and polypropylene by industrial and laboratory scale corona treatments and by laboratory flame treatment was studied. The surface sensitive techniques of X-ray photoelectron spectroscopy (XPS), attenuated total reflection infra-red spectroscopy (FTIR-ATR), contact angle measurement and electron microscopy (SEM and TEM) were employed. Corona and flame treatments resulted in incorporation of oxygen only into the surfaces of both polyethylene and polypropylene, resulting in improved surface wettabilities. A variety of oxygen functional groups were introduced by the two treatments. The industrial and laboratory scale treatments of both polymers were found to be similar in terms of the oxygen concentrations incorporated and surface wettabilities achieved. The presence of significant amounts of chain scission products were indicated on corona treated surfaces, while only minimal quantities were indicted on flame treated surfaces. This was attributed to their volatilisation during flame treatment. Introduction of sulfur dioxide into the flame and corona regions during treatment resulted in significant improvements in surface wettability. Incorporation of sulfur and nitrogen resulted from the presence of sulfur dioxide. A possible mechanism involving the formation of sulfonic acid groups and ammonium sulfonate groups was suggested. An oxidation depth model developed for use with variable take-off angle XPS showed that significantly deeper oxidation occurred in the presence of sulfur dioxide. Corona treatment was more effective in improving surface wettabilities than flame treatment, this being attributed to heat induced functional group reorientation during flame . treatment for polyethylene and to differences in surface chemistry resulting from the two treatments in the case of polypropylene. The surface wettability of poly ethylene was more readily improved than the surface wettability of polypropylene after all the treatments investigated. A method for estimating functional group concentrations using chemical derivatisation and contact angle measurement was developed. Functional group estimates for flame treated polyethylene were found to be in good agreement with chemical derivatisation used in conjunction with XPS measurements.

Abstract: Clathrate hydrates are compounds where guest molecules are trapped in cages formed between water molecules via hydrogen bonding. They have many promising applications, such as gas storage, energy storage, gas mixture separation and seawater desalination. They may also form inside the oil & gas pipelines at a fast rate and pose a threat to flow assurance. Despite extensive research on physicochemical properties of clathrate hydrates, many knowledge gaps still remain to be filled. This study presented a systematic investigation on interfacial and surface phenomena of clathrate and semi-clathrate hydrates, including the determination of specific surface free energy and tangential adhesive strength, the quantification of CO2 hydrate nucleation kinetics, the elucidation of the memory effect and the evaluation of the effect of dispersion on nucleation kinetics and gas uptake capacity of CO2 hydrate. The specific surface free energy (γsv) value of THF hydrate was deduced using an indirect method in the range from 60.4 to 124.2 mJ/m2, with an average of 92.3 mJ/m2, which was somewhat lower than that of ice. The determination of this fundamental parameter is essential to the understanding of surface phenomena of clathrate hydrates. Tangential adhesive strength (τ) of THF hydrate and TBAB semi-clathrate hydrate on substrates with different hydrophobicity was measured. Results showed: 1) diminished values of τ as heating which was speculated to be caused by pre-melting; 2) increased values of τ upon the addition of PVP (a kinetic hydrate inhibitor) on all substrates and 3) higher values of τ on the hydrophobic substrates than on the hydrophilic ones. Our findings may be valuable to hydrate-related flow assurance problems in oil & gas pipelines during hydrodynamic transport. Nucleation rate of CO2 hydrate (sI) was determined using a linear cooling ramp method in the presence and absence of a solid wall. It was found: 1) the convergence of nucleation curves with an increasing number of data points; 2) the promoting effect of a stainless-steel wall on hydrate nucleation kinetics; 3) the limitation of Classical Nucleation Theory in explaining hydrate nucleation and 4) the major effect of the guest type on hydrate nucleation kinetics. Our findings offered new insights into the quantification of CO2 hydrate nucleation kinetics and impact factors of it. The mechanism of the memory effect was investigated by comparing nucleation curves of CO2 hydrate formation in fresh and dissociated water. Despite different “amount”, the memory effect was detected when CO2 hydrate formed in dissociated water both in the presence and absence of a solid wall. A new mechanism was proposed——the memory effect was caused by two components, interfacial gaseous states and bulk guest supersaturation (with or without nanobubbles), with the former one being more effective in size. Our hypothesis supplemented and improved existing hypotheses and might solve this mystery. The effect of dispersion on CO2 hydrate formation kinetics was researched in dry water. Results showed that dry water remained stable after being doped with a small amount of nucleation promoters. The presence of SDS and nucleation promoters had no promoting effect on the nucleation kinetics of CO2 hydrate but significantly promoted crystal growth kinetics of the CO2 hydrate formation in dry water. We concluded that dispersion and additives promoted CO2 hydrate nucleation and crystal growth, respectively. Our findings can be utilized to store more CO2 in a hydrate form at a faster rate. Overall, we deduced the essential parameter that characterizes the surface properties of hydrates, specific surface free energy. This offered a pathway for the estimation of the work of adhesion and nucleation work. We investigated the influencing factors on hydrate-substrate shear adhesive strengths, which is meaningful for flow assurance. We derived nucleation rates of CO2 hydrate and elucidated the influencing factors of it, providing a baseline for the industry. We proposed a mechanism explaining the memory effect and it shed light on this long-standing mystery. We investigated the effect of dispersion and additives on CO2 hydrate formation kinetics. The main findings are significant for the application of gas hydrates in carbon capture and sequestration and relief of the greenhouse effect. This thesis not only advanced the basic understanding and the fundamental knowledge of the surface and interfacial properties of gas hydrates but also provided insightful guidance for the hydrate-related industry.

This study investigated the effects of asphalt oxidation and testing temperature on moisture damage in asphalt mixtures, using AASHTO T283 and Surface Free Energy (SFE) testing. The study assessed the impact of three asphalt binder grades (PG 64-22, PG 76-22, and PG 52-34) and three test temperatures (ALT, AIT, and CIT) on the susceptibility to moisture damage. Additionally, three oxidation levels (OTC, STOC, and LTOC) were evaluated to determine the optimal level of oxidation and testing temperature for AASHTO T283 to detect moisture damage. Load-displacement curve parameters and IDEAL-CT were analyzed to better understand the effects of oxidation and moisture conditioning on asphalt mixtures. The study also evaluated the effects of three oxidative levels (OB, RTFO, and PAV20) on moisture damage susceptibility using SFE testing. Fourier transform infrared spectroscopy (FTIR) attenuated total reflectance (ATR) was also used to quantify the effects of oxidative conditioning on asphalt binder chemical properties. The findings suggest that asphalt mixtures are more susceptible to moisture damage at STOC and LTOC than OTC, and that oxidation and CIT have the greatest impact on moisture damage susceptibility. The study highlights the need for an alternative oxidation conditioning and testing at CIT to detect moisture damage more accurately in asphalt mixtures.

Moisture-induced damage is one of the major distresses which leads to the deterioration of mechanical properties of asphalt mixes and failure of asphalt pavements. Evaluation of the moisture-induced damage potential is a challenging task because a number of factors including physical and chemical properties of aggregates and binders, aging, additives/polymers and other environmental and traffic conditions can significantly influence the adhesion and/or cohesion mechanisms of an asphalt mix. Previous studies have reported inadequacies of the current moisture-induced damage evaluation methods on their ability to address mechanisms that lead to failure of asphalt pavements. There is a need to identify relatively simple, reliable, and mechanistic methods for evaluating moisture-induced damage potential of asphalt mixes. In this study, mechanistic approaches based on the thermodynamic theory, chemical characterization and laboratory-based performance tests were used to investigate the effects of different factors on the moisture-induced damage potential of asphalt mixes. Specifically, the thermodynamic theory using surface free energy (SFE) of constituent materials was used to mechanistically quantify the bonding strength of binder-aggregate systems. Attempts were made to study the effect of probe liquid sets and different SFE estimation methods on the calculation of moisture-induced damage of binder-aggregate systems. Suitable probe liquid sets to produce accurate and consistent energy parameters for binder-aggregate systems were identified. The changes in the bonding characteristics of an unmodified PG 64-22 and a polymer-modified PG 76-28 binders with the addition of different additives, namely warm mix asphalt (WMA) additive, anti-stripping agent (ASA), polyphosphoric acid (PPA) and reclaimed asphalt pavement (RAP) were determined using the SFE method. Also, the compatibility of these binders with commonly available aggregates under different aging conditions was investigated. Fourier transform infrared (FTIR) spectroscopy and X-ray fluorescence (XRF) tests were conducted on the binders to examine the effects of chemical compositions on the moisture-induced damage potential of asphalt mixes. The elemental compositions of aggregates were determined using the XRF results. Asphalt mixes containing different additives were produced in the laboratory for the evaluation of moisture-induced damage using Hamburg wheel tracking (HWT), indirect tensile strength (ITS) and two different semi-circular bend (SCB) tests, namely Louisiana SCB (LA-SCB) and Illinois SCB (IL-SCB) tests. Correlations between different laboratory-based moisture-induced damage parameters and the SFE parameters were investigated. The results of the SFE parameters and chemical analyses indicated that the properties of aggregates have significantly higher influence on the moisture-induced damage potential of a mix than the properties of binder. Also, asphalt mixes, in general, were found to become more prone to moisture-induced damage with in-service aging. The presence of amine group in both WMA and ASA was found to reduce the moisture susceptibility of asphalt mixes. However, the modification of binder with PPA is expected to increase the moisture-induced damage potential of a mix. Unconventional laboratory-based parameters from conventional tests, namely stripping number (LCSN) from HWT test and toughness index ratio (TI ratio) from ITS test exhibited potential to adequately characterize mixes for moisture-induced damage. Also, SCB test-based parameters, namely J-integral ratio (Jc ratio) from LA-SCB and fracture energy ratio (Gf ratio) from Illinois-SCB showed promises for use as alternate moisture-induced damage parameters for asphalt mixes.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) show great potential for the future electronics, optoelectronics and energy applications. But, the studies unveiling their interactions with the host substrates are sparse and limits their practical use for real device applications. We report the facile nano-scratch method to determine the adhesion energy of the wafer scale MoS2 atomic layers attached to the SiO2/Si and sapphire substrates. The practical adhesion energy of monolayer MoS2 on the SiO2/Si substrate is 7.78 J/m2. The practical adhesion energy was found to be an increasing function of the MoS2 thickness. Unlike SiO2/Si substrates, MoS2 films grown on the sapphire possess higher bonding energy, which is attributed to the defect-free growth and less number of grain boundaries, as well as less stress and strain stored at the interface owing to the similarity of Thermal Expansion Coefficient (TEC) between MoS2 films and sapphire substrate. Furthermore, we calculated the surface free energy of 2D MoS2 by the facile contact angle measurements and Neumann model fitting. A surface free energy ~85.3 mJ/m2 in few layers thick MoS2 manifests the hydrophilic nature of 2D MoS2. The high surface energy of MoS2 helps explain the good bonding strength at MoS2/substrate interface. This simple adhesion energy and surface energy measurement methodology could further apply to other TMDs for their widespread use.

The fundamental forces of adhesion are responsible for the spreading of fluids such as crude oil/brine on the reservoir rock surface. These physico-chemical interactions determine the surface energetics of a reservoir and thus their wetting phenomena. A systematic approach to characterize the mixed wet configurations of various reservoir rocks (sandstone and carbonates) by evaluating their surface energy distributions has been presented here. This approach was tested against macroscopic spatial distribution of oil-wet and water-wet sites and at different temperatures for validation. The new approach used to characterize the mixed wettability of a reservoir rock pertains to establishing a relation between the volume fraction of the mixed wet reservoir rocks and surface energy of the mixture. This approach is based on an accurate description of the various physico-chemical interfacial forces present at the reservoir rock surface using Inverse Gas Chromatography (IGC). Inverse Gas Chromatography is introduced to characterize the surface energy of several carbonate (Calcite and Dolomite) and sandstone rocks (Ottawa sand and Berea sandstone). The behavior of the Lifshitz-van der Waals and acid-base interaction forces acting on the rock surface was investigated at varying water coverage and at different temperatures in association with their surface chemistry. Mixed-wet configurations of various reservoir rocks are created by combining water-wet and oil-wet samples of the rock in different volume fractions and shaken together to establish uniform distribution. These samples were then subjected to the IGC analysis at different temperatures to deduce their surface energy distribution. The relation developed herein was tested against spatial heterogeneity by combining the oil-wet and water-wet rock samples in a layered fashion to validate the approach. A definite and conclusive relationship between the surface energy and mixed wettability of silica glass beads, calcite and dolomite samples was established in this study. The mixed wet configurations of the rock samples ranged from 0% oil wet (meaning water-wet samples) to 100% oil wet samples. The findings indicated that the Lifshitz-van der Waals component of the rock mixture did not undergo any change with change in the wetting state of the system under study. However the acid base components showed a marked decrease with increasing oil wetness before plateauing. Temperature was found to have a profound impact on the surface energy of a rock surface. Spatial heterogeneity by way of layered and segregated distribution of oil-wet and water-wet sites did not affect the eventual surface energy distribution and thus validating the new approach. The novelty of this work is that using this approach the mixed wettability any reservoir rock can be reliably and accurately determined in the shortest and most non-destructive manner using Inverse Gas Chromatography. Finally surface science concepts developed in this study were applied to study another adhesion problem pertaining to asphaltene deposition in the well-bore at varying flowrates, temperature and concentration.

Superhydrophobicity is a property commonly seen in nature such as the lotus leaf. This unique property allows the surface of a material to exhibit water repellency and self-cleaning abilities. This effect is contributed by two important components: the rough surface topography and low surface free energy. Since the discovery of this unique property, several methods and various materials have been used to produce this effect and used in a wide variety of applications. However, the use of this type of effect on transparent surfaces is still being researched. I have proposed a method to develop a transparent superhydrophobic coating using a transparent polymer such as Polycarbonate (PC) as a matrix . Functionalized aerogel particles are broken down to nanosized particles by milling and sonication, and added into solution with PC. This solution is then applied on various substrates such as quartz and silicon wafers though a spin coating process. The film produced is transparent with a transmission of 92-93%. The increase in coating thickness showed only a slight reduction in the transmission; however, the transmission still exhibited an equal or higher transmission than observed for quartz glass without a coating. The superhydrophobic properties were obtained based on contact angle measurements of 150° or greater, which represent a combination of low surface free energy and nano-textured topography of the coating. Another important aspect to achieving a superhydrophobic coating is the addition of a rough surface topography. The SEM and AFM measurement indicates that the superhydrophobic polycarbonate coating (SHPC) coating exhibits the rough nano-textured topography for obtaining superhydrophobicity. The mechanical properties of the film indicated a decrease in hardness and modulus with the increase of the coating thickness, which is influenced by the substrate. This method has shown to be a simple and effective method that can be applied to a variety of substrates and can be expanded to being used for coating larger surfaces through different methods, such as spray coating. The coating has the potential to be used for various transparent applications, such as camera lenses, windows, and solar panels.

We used substrates of poly(methyl methacrylate) (PMMA) to investigate the influence of nanotopography on the osteogenic phenotype of mesenchymal stem cells (MSCs), focusing on their ability to produce mineral similar to bone. Topography induced anisotropy in contact angles and surface free energy (SFE). Smooth PMMA had an SFE of 40 mN/m. Topographic surfaces had elevated and reduced SFEs when measuring parallel (up to ~45 mN/m ) or perpendicular to the gratings (as low as ~31 mN/m). Topography influenced alignment and enhanced MSC proliferation after 14 days of culture. Focal adhesion size was influenced after 7 days. Calcium deposition was not increased after 21 days. Ca: P ratios were similar to native mouse bone on films with gratings of 415 nm width and 200 nm depth (G415) and 303 nm width and 190 nm depth (G303). Notably, all surfaces had Ca:P ratios significantly lower than G415 films (less than 1.39). We used thin films of poly(ethylene glycol diacrylate) (PEGDA) with nanoscale gratings and tunable elasticity to investigate the potential synergistic effect on the osteogenic phenotype of MSCs. Three distinct moduli were used having a shear storage modulus of ~64, 300, and 530 kPa respectively. Topography did not influence cell alignment nor did the combination of matrix topography and elasticity enhance the calcium deposition or Ca:P ratios. Collagen I density (5 or 50 µg/mL) did not significantly influence calcium deposition. These data demonstrate that nanotopographic PMMA films, mimicking the architecture of bone, do not enhance calcium levels in mineral deposited by hMSCs. We showed that increased focal adhesion size on PMMA nanotopography is insufficient by itself to drive increased calcium deposition. Reports in literature rarely quantify changes in focal adhesions with changes in mineral quantity and composition. Similarly, an in vivo report suggests that topography does not enhance osteogenesis. In the first known attempt to combine adhesion ligand concentration (Col I) to nanogratings on surfaces with varied mechanical properties, these inputs were insufficient to synergistically enhance an osteogenic phenotype in MSCs. We highlight the importance of studying functional output rather than minor markers as function is a greater indicator of differentiation.

Implant-associated bacterial infections are one of the most serious complications in orthopedic surgery. Treatment of these infections often requires multiple operations, device removal, long-term systemic antibiotics, and extended rehabilitation, and is frequently ineffective, leading to worse clinical outcomes and increased financial costs. In the current study, we found that silver nanoparticle/poly (DL-lactic-co-glycolic acid) (PLGA)-coated metal materials have bactericidal activity in a silver-proportion-dependent manner and inhibit bacterial adherence and biofilm formation in vitro, ex vitro and in vivo. Interestingly, we also found silver nanoparticle/PLGA-coated stainless steel (SNPSA) materials have osteoinductivity they promoted MC3T3-E1 pre-osteoblast proliferation and osteogenesis in vitro and bone formation in rat femoral canal and intramedullary rod models. On the other hand, silver nanoparticle/PLGA-coated titanium (SNPT) materials did not show osteoinductivity. By comparing the surface properties of SNPSA and SNPT materials, we determined that SNPSA materials exhibit higher surface electrostatic potential than SNPT that may provide a stronger electric stimulation for bone regeneration. In addition, we found that SNPSA materials have higher surface free energy and hydrophilicity than SNPT materials that may enhance protein absorption and subsequently bone formation. Taken together, our results indicate that silver nanoparticle/PLGA coating of stainless steel is a practical process for implants of orthopedic to control implant-associated infections and improve bone healing.

Warm Mix Asphalt (WMA) was introduced in Europe in 1995. WMA is gaining attention because it offers several advantages over Hot Mix Asphalt (HMA). The advantages include (1) reduced energy consumption in the asphalt mixture production process; (2) reduced emissions, fumes, and undesirable odors; (3) reduced binder aging;and (4) extended construction season in temperate climates.Moisture damage can be defined as the effect of environmental factors such as water, temperature, and air on the performance of asphalt concrete pavement. The asphalt mix consists of aggregate (in different sizes) and asphalt binder being compacted to a specified air void ratio. Due to traffic load with existence of water, asphalt concrete mix will start to lose adhesion between aggregate and binder or lose cohesion within the binder itself.The main objective of this study is to assess the performance of WMA and HMA in presence of water by using nano scale techniques and Surface Free Energy (SFE)concepts, and then compare the results with asphalt pavement traditional laboratory tests.In this study, the bitumen’s main functional groups were determined by using Fourier Transform Infrared (FTIR) Spectroscopy. The mineral compositions of aggregate were analyzed by using X-Ray diffraction (XRD) technique. Atomic Force Microscopy (AFM) was used to measure the surface free energy of aggregate and asphalt binder. It can also be used to make a high quality (Three Dimensional) images for smooth and leveled surfaces. Asphalt mix samples were prepared in the laboratory using Superpave Gyratory Compactor (SGC) with different thicknesses and diameters. Half of the asphalt mix samples were conditioned to study the effect of moisture on the performance of the mix. Air void structure and aggregate orientation of the asphalt mix were examined by using X-Ray Computed Tomography (X-Ray CT). X-Ray CT images were analyzed by using computer software called AVIZO Fire (version 6.3) to measure the air void ratio, void sizes, and void distribution.Simple Performance Tester (SPT) was used to perform dynamic modulus test. The test was performed on both unconditioned and conditioned samples to compare the results. MTS machine was used to perform the Indirect Tensile Strength (ITS) on the unconditioned and conditioned asphalt mix samples. Thermal cracking temperature for compacted asphalt sample was determined by using Asphalt Concrete Cracking Device (ACCD). The permanent deformation (Rutting) of asphalt concrete was determined by using Asphalt Pavement Analyzer (APA). Based on the traditional laboratory test results, all mixes are high resistant to moisture damage with slight differences in the performance of HMA over WMA.Dynamic modulus test results were used as inputs to find the relaxation modulus and creep compliance. Two asphalt mixes from two different plants in the state of Ohio were evaluated. Based on the traditional laboratory tests results, the performance of the HMA was higher than the WMA for each project and this is can be caused by the foaming process. Ohio foaming process consists only of one stage where the foamed hard binder is introduced to the mixture to decrease the mixing temperature. Ohio-Foam’s system willincrease the void ratio of the asphalt mix and more water will be trapped within the aggregate-binder interface. To reduce the voids in the WMA, regular HMA can be used to remove the city water from the mixing process, replace Ohio-Foam’s system with the soft-hard binder foaming process, or another foaming WMA technique can be used such as Advera. The performance of the asphalt mixes from Columbus, Oh was higher than the performance of the asphalt mixes from Woodville, Oh and this is can be caused by the mineralogical composition of the aggregates. Columbus aggregates contains more silica (SiO2) than Woodville aggregates and based on AFM results, it was clear that the sandstone (more silica SiO2) is better than limestone in terms of providing greater adhesion energy with the binder. To enhance a better performance of Woodville HMA and WMA, a different aggregate source can be used.

Abstract: The impact of cranberry juice was investigated with respect to the initial adhesion of three isogenic Burkholderia cepacia bacteria with different extracellular polymeric substance (EPS) producing capacities: a wild-type cepacian EPS producer PC184, mutant bacteria PC184rml with reduced EPS production, and PC184bceK with a deficiency in EPS production. Adhesion experiments demonstrated that in the presence of cranberry juice, the adhesive capacity of PC184 was largely reduced, while cranberry juice had little impact on the adhesion of either mutant. Thermodynamic modeling supported results from adhesion experiments. For PC184, the surface free energy change ΔGadh switched from negative in the absence of cranberry juice to positive when cranberry juice was added. Surface force apparatus (SFA) and scanning electron microscopy (SEM) studies demonstrated strong adsorption of cranberry juice components to bacterial EPS. It was concluded that cranberry juice components could impact bacterial initial adhesion by adhering to EPS and impairing bacterial adhesive capacity.

The correlation between the wettability of soil materials and soil chemical composition and surface energy is examined. Wettability, as measured by the contact angle, is a governing parameter of capillary flow in the subsurface. The contact angle is determined by the intermolecular forces at the intersection of a drop with a surface and surrounding fluid. It was previously assumed that although most soil materials are water wet, similar to quartz sands, some organic-carbon containing materials may be hydrophobic. However, this work determines that some common subsurface media may have radically different wetting behavior depending on the past wetting history even in the absence of surface active agents. The wettability of four organic carbon containing natural soil materials (Ann Arbor II sand, Lachine shale, Garfield shale, and Waynesburg Coal), three carbon containing mineral materials (graphite, dolomite, and calcite), and two pure mineral materials (quartz and talc) was measured by bottle tests and sessile contact angle measurements. The liquid systems examined included air-water, perchloroethylene-water, and carbon tetrachloride-water. The wettability of soil materials is shown to depend on the order of fluid contact with the surface such that some soils (talc and organic carbon-containing materials) are non-water wet if contacted by a non-aqueous phase first. This relatively unexplored phenomenon is termed wettability hysteresis and may indicate that the wettability of some soils will differ depending on the saturation of the system. The effect of the surface composition on the contact angle and degree of hysteresis was quantified by measuring the surface energy components of the surface. It is shown that oxygen indices are a better predictor of contact angle and wettability hysteresis than carbon content. The surface energy components (dispersion, polar, and total) of each solid are determined by the van Oss-Chaudhury-Good method and the polar surface energy component is shown to determine wettability hysteresis. Evidence that a water film forms when water is the first fluid to contact the surface, causing wettability hysteresis, is provided from multiple approaches. The estimation of contact angle and wettability hysteresis based on the polar surface energy component is presented.

In general, the stability of suspension can be studied using two methods. One is to directly measure the forces between two interacting surfaces in media. The other is to study the interfacial surface free energies of the particles in suspension. Direct surface force measurements were conducted between silica surfaces in octadecyltrimetylammonium chloride (C₁₈TACl) solutions using an Atomic Force Microscope (AFM). The results showed that the hydrophobic force existed in both air-saturated and degassed C₁₈TACl solutions. The attraction decreased with NaCl addition, and was the strongest at the point of charge neutralization (p.c.n.) of silica substrate. The force measurement results obtained in CnTACl solutions showed that the attractions decayed exponentially and became the maximum at the p.c.n.'s. The decay lengths (D) increased with surfactant chain length. The measured forces were fitted to a charged-patch model of Miklavic et al. (1994) with rather large patch sizes. It was also found that the decay length decreased linearly with the effective concentration of the CH2/CH3 groups raised to the power of -1/2. This finding is in line with the model of Eriksson et al. (1989). It suggested that the long-range attractions are hydrophobic forces originating from the changes in water structure across a hydrophobic surface-solution interface. For the TiO₂/water/TiO₂ system, the Hamaker constant was found to be 4±1×10-20 J. The force curves obtained in the TiO₂/CnTACl system showed a repulsion-attraction-repulsion transition with increasing surfactant concentration. The long-range attraction observed between TiO₂ surfaces in CnTACl solutions reached maximum at the p.c.n., and the decay length increased with chain length. In present work, the thin-layer wicking technique was used to determine the surface free energy (γs) and its components of talc samples. The results showed that the basal surfaces of talc are weakly basic while the edge surfaces are acidic. The effect of chemicals on the surface free energies of talc was systemically studied. The results showed that CMC (carboxymethyl cellulose sodium salt) and EO/PO (ethylene oxide/propylene oxide) co-polymers made talc surface hydrophilic by increasing the surface free energies, especially γLW and γ -. SOPA (sodium polyacrylate) increased greatly the zeta-potentials instead of the surface free energies.

Microcalorimetric measurements and contact angle measurements were conducted to assess the surface chemistry of the mineral talc. The contact angles were performed on both flat and powdered samples and the results were used to determine the surface free energy components and parameters (SFEC) using the acid-base theory for solids, according to the van Oss-Chaudhury-Good approach. It was found that the surface hydrophobicity of talc increases with decreasing particle size up to a limit after which hydrophilicity (polarity) increases. The increase in hydrophobicity was attributed to the increase of the delamination of the lamellar talc particles. Delamination is a comminution mechanism that preferentially exposes talc's hydrophobic basal planes, while fracture is another mechanism that breaks the lamellae, rupturing covalent bonds thus exposing more hydrophilic edge surfaces. The decrease in hydrophobicity, beyond a given particle size, could be related to the prevail of fracture over delamination during grinding which generated more hydrophilic edge surfaces. The flow microcalorymetry combined with thin layer wicking allowed the separate estimation of the SFEC at the basal plane and edge surfaces of talc. The results suggested that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic, which are in agreement with the crystal structure of the mineral. The combination of two particle size distribution techniques, which are based on different physical principles, permitted the quantitative determination of the aspect ratio of highly anisometric particles, such as talc. The same trend obtained using flow microcalorimetry was observed for the evolution of the aspect ratio as a function of particle fineness, i.e. the fracture prevails over delamination after achieving a maximum aspect ratio value of about 35. The agreement between two distinct methods was considered rather encouraging.

The induction of cytochrome P450 (CYP) 3A enzymes (human isoform, CYP3A4) is a common cause of serious drug interactions. Recent cloned pregnane X receptor (PXR) is suggested to be a key transcription factor regulating CYP3A expression. We hypothesized that docetaxel and paclitaxel, two structurally similar taxane anti-cancer drugs, differ in their potential to induce CYP3A and in activating PXR. Employing primary mouse, rat and human hepatocytes, we assessed the influence of taxanes, relative to known CYP3A inducers, rifampicin and phenobarbital, on the CYP3A activity (rate of testosterone 6β, CYP3A-specific immunoreactive protein (Western-blot analysis) and mRNA levels (Northern-blot analysis). We then determined the differences in the hepatocyte uptake and the magnitude of PXR activation (employing cell based reporter assays) by docetaxel and paclitaxel. Finally, employing wild type and PXR null mice we probed the in vivo PXR involvement in CYP3A induction by taxanes. We observed that while paclitaxel and docetaxel both significantly induced CYP3A in mouse and rat hepatocytes, only paclitaxel induced CYP3A in human hepatocytes. Furthermore, while paclitaxel and docetaxel both considerably activated mouse PXR, human PXR activation by docetaxel was markedly lower compared to paclitaxel. Moreover, the CYP3A induction by taxanes in wild-type C57Bl6 mice was completely abolished in PXR null mice. Another importance observation was that the uptake of paclitaxel in human hepatocytes was markedly higher than that of docetaxel. Taken together, our studies have made several very important observations. Firstly, docetaxel has markedly reduced potential to induce CYP3A4 in humans compared to paclitaxel, which suggests that docetaxel is a safer drug to use. Secondly, both pharmacokinetic (cellular uptake) and pharmacodynamic (PXR activation) differences may account for the observed differences in CYP3A induction by paclitaxel and docetaxel. PXR activation assays may be employed as an initial screen for the development of the next generation of taxanes.

Microcalorimetric measurements and contact angle measurements were conducted to study the surface chemistry of powdered minerals. The contact angle measurements were conducted on both flat and powdered talc samples, and the results were used to determine the surface free energy components using Van Oss-Chaudhury-Good (OCG) equation. It was found that the surface hydrophobicity of talc increases with decreasing particle size. At the same time, both the Lifshitz-van der Waals (gSLW) and the Lewis acid-base (gSAB) components (and, hence, the total surface free energy (gS)) decrease with decreasing particle size. The increase in the surface hydrophobicity and the decrease in surface free energy (gS) can be attributed to preferential breakage of the mineral along the basal plane, resulting in the exposure of more basal plane surfaces to the aqueous phase. Heats of immersion measurements were conducted using a flow microcalorimeter on a number of powdered talc samples. The results were then used to calculate the contact angles using a rigorous thermodynamic relation. The measured heat of immersion values in water and calculated contact angles showed that the surface hydrophobicity of talc samples increase with decreasing particle size, which agrees with the direct contact angle measurements. A relationship between advancing water contact angle qa, and the heat of immersion (-DHi) and surface free energies was established. It was found that the value of -DHi decrease as qa increases. The microcalorimetric and direct contact angle measurements showed that acid-base interactions play a crucial role in the interaction between talc and liquid. Using the Van Oss-Chaudhury-Good's surface free energy components model, various talc powders were characterized in terms of their acidic and basic properties. It was found that the magnitude of the Lewis electron donor, gS-, and the Lewis electron acceptor, gS+, components of surface free energy is directly related to the particle size. The gS- of talc surface increased with decreasing particle size, while the gS+ slightly decreased. It was also found that the Lewis electron-donor component on talc surface is much higher than the Lewis electron-acceptor component, suggesting that the basal surface of talc is basic. The heats of adsorption of butanol on various talc samples from n-heptane solution were also determined using a flow microcalorimeter. The heats of adsorption values were used to estimate % hydrophilicity and hydrophobicity and the areal ratios of the various talc samples. In addition, contact angle and heat of butanol adsorption measurements were conducted on a run-of-mine talc sample that has been ground to two different particle size fractions, i.e., d50=12.5 mm and d50=3.0 mm, respectively. The results were used to estimate the surface free energy components at the basal and edge surfaces of talc. It was found that the total surface free energy (gS) at the basal plane surface of talc is much lower than the total surface free energy at the edge surface. The results suggest also that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic. The results explain why the basicity of talc surface increases with decreasing particle size as shown in the contact angle and microcalorimetric measurements. Furthermore, the effects of the surface free energies of solids during separation from each other by flotation and selective flocculation were studied. In the present work, a kaolin clay sample from east Georgia was used for the beneficiation tests. First, the crude kaolin was subjected to flotation and selective flocculation experiments to remove discoloring impurities (i.e., anatase (TiO2) and iron oxides) and produce high-brightness clay with GE brightness higher than 90%. The results showed that a clay product with +90% brightness could be obtained with recoveries (or yields) higher than 80% using selective flocculation technique. It was also found that a proper control of surface hydrophobicity of anatase is crucially important for a successful flotation and selective flocculation process. Heats of immersion, heats of adsorption and contact angle measurements were conducted on pure anatase surface to determine the changes in the surface free energies as a function of the surfactant dosage (e.g. hydroxamate) used for the surface treatment. The results showed that the magnitude of the contact angle and, hence, the surface free energy and its components on anatase surface varies significantly with the amount of surfactant used for the surface treatment.