This research has investigated the effects of a dilute urea solution, an acid-simulated perspiration solution, and distilled water on a polyurethane-coated fabric. Investigations were made into the feasibility of using the Glass Plate Method, where treated samples were heated between glass plates and the LaunderOmeter® Method where samples were treated with solutions in an enclosed system in a constant temperature bath. The degradative effects of the solutions, when used with the Glass Plate Method, were measured by flex and surface abrasion and the degradative effects of the solutions, when used with the LaunderOmeter® Method, were measured by surface abrasion. The pH was observed before and after treatments in the LaunderOmeter® . It was found that the urethane film of the test fabric could be completely decomposed with all three solutions when treated at 95°C for six hours in the LaunderOmeter®. However, those samples treated with urea had higher abrasion resistance and appeared less decomposed visually. This was in conflict with reports that the addition of urea to distilled water would increase the rate of hydrolysis, and could be used to simulate perspiration. This is assuming that the effects of the solutions were indeed causing hydrolysis. The LaunderOmeter® Method was found to be more controllable than the Glass Plate Method. Replications of treatments at 72°C for two hours were carried out on the polyurethane synthetic leathers using the LaunderOmeter® Method. Again, the urea-treated samples demonstrated a higher abrasion resistance. Distilled water and the acid-simulated perspiration solution gave comparable results. / Master of Science

Many treatment facilities remove soluble Mn by an autocatalytic adsorption-oxidation process involving manganese oxide (MnOx(s))-coated filter media and a free chlorine residual known as the natural greensand effect (NGE). In recent years, significant amounts of aluminum (Al) have been found integrated into MnOx(s) coatings on media from drinking water treatment facilities worldwide. The primary objective of this study was to characterize MnOx(s) coatings developed in the presence and absence of Al, and to further define the role played by Al in the coatings' initiation and development. A secondary objective of the study was to examine the potential for pre-filter oxidation of Mn and formation of nano-size MnOx(s) particles, which would be destabilized by Al(OH)3(s) and captured in the filter. This material could act as a seed for coating formation and help explain the integration of Al into MnOx(s) coatings. Bench-scale column tests were conducted to examine Mn removal and backwash composition, while centrifugation and ultrafiltration were utilized to examine the potential for rapid Mn oxidation. Results indicate that the presence of Al augments the initiation and development of MnOx(s) coatings. The backwash solids of columns loaded with Al were composed of a mixture of Mn and Al, suggesting that active adsorption-oxidation sites were present in the Al(OH)3(s) floc captured by the filter. These results suggest at least a small amount of pre-filter MnOx(s) formation by contact with free chlorine; further, that Al(OH)3(s) solids present may destabilize these negatively charged solids into a form that is important to MnOx(s) coating formation. / Master of Science

The Mn oxide (MnOx(s)) surfaces of water treatment filtration media are known to aid in the capture of dissolved Mn species, but the discovery of significant deposits of Al within these coatings raised several questions about the MnOx(s) surface. A series of experiments and analyses were performed to examine the presence of Al within MnOx(s) coatings formed on water treatment filtration media. It was hypothesized that the presence of Al within the MnOx(s) coatings might have an impact on the capture of Mn by the MnOx(s) surface. A 2008 study of oxide coated filtration media found that Mn and Al are present in nearly equimolar quantities within the oxide coatings. This led to questions of how and why the Al became incorporated into the surface. This phenomenon was analyzed by conducting a series of bench-scale column studies, treatment plant data collection, and analysis of the MnOx(s) surface utilizing an electron microscope. The results confirm that Al deposits onto the MnOx(s) media surface by two separate mechanisms; adsorption of dissolved Al species and the deposition of colloidal and particulate Al(OH)3(s) precipitate species onto the surface. Analysis of the MnOx(s) coating with by electron microscopy shows a heterogeneous surface composed of a mix of crystalline Mn oxides existing alongside amorphous Al(OH)3(s) species. The deposition of Al onto the media surface does not have any significant effect on the removal of soluble Mn, but the potential impact that Al might have on the capture of other dissolved species should be explored further. / Master of Science

No description available.

High Speed Machining (HSM) is associated with higher cutting velocities and table feedrates and higher material removal rate, lower cutting forces in contrast to conventional machining. HSM can be undertaken dry or near dry and hence it is considered as environmentally friendly machining in relation to the use of cutting fluids. A key challenge in HSM is that, the thermal loads generated during the cutting process can be a major driver of thermally activated wear mechanism and hence affect machining performance. The ability of cutting tools to act as thermal barrier can be a highly desirable property for dry and HSM. Recently, research work has been conducted on laboratory based coated cutting tools to model and understand the fraction of heat that enters the cutting tool. These studies have shown the potential for TiN and TiAlN coated tools in reducing heat partition to the cutting tool when compared to uncoated tools. This PhD extended this work to modelling and characterising the heat partition for new generation commercial coated cutting tools considering tools from major insert manufactures. For this study commercial coated carbide tools were classified into two groups. In one group were coatings uniformly applied on both rake and flank faces of the insert (SERIES). The second group were tools that had different top coats for the rake and flank faces (Functionally Graded). This concept of functional grading is used to tailor the coating selection to the conditions that exist on a tool face. Moreover, the issue of restricted chip contact was modelled and clarified in terms of its impact on heat partition. This chip breaker design is of particular importance to inserts used for machining ductile materials. Thus the PhD has applied research methods to industrial cutting tools and helped elucidate the important aspects relating to the design, layout and selection of multilayer coatings. The heat partition was quantified by using a combined Finite Element (FE) and experimental approach. This methodology was applied by taking into consideration the appropriate friction phenomena during HSM i.e. sticking and sliding. A restricted contact length with groove profile geometry was considered for the application of heat load in the FE model. Orthogonal and external turning of AISI/SAE 4140 medium carbon alloy steel was conducted over a wide range of cutting speeds. An infrared thermal imaging camera was used to measure cutting temperatures. The results show that the layout of the coating can significantly affect the heat distribution into the cutting tool, specifically; the top coat can alter the friction conditions between the tool-chip contact. The distribution of heat (heat partition) into the cutting tool insert with the thickest layer of Al2O3 as a top coating is the lowest in the entire range of cutting speeds tested i.e. 10.5% at lower cutting speed and reduced to 3.4% at highest cutting speed. Investigations were also conducted to quantify the contribution of heat from the primary and secondary deformation zones using a combination of finite element modelling, analytical modelling and experimental data. The results deduced that the primary deformation zone heat source contributes 9.1% (on average) to the heat partition into the cutting tool. The contribution of the Thesis should be of interest to those who design, manufacture and coat cutting tools. It defines heat partition values for commercial coated carbide tools, assesses the requirements for multilayer design of thermally insulating cutting tools, the selection of coating top layer coats and the role of contact phenomenon on heat partition in dry and HSM of steels.

Titanium and its alloy (Ti-6Al-4V) are widely used in aerospace industries because of their light weight, high specific strength, and corrosion resistance. This study conducted a comparative experimental analysis of the machinability of Ti-6Al-4V for conventional flood coolant machining and sustainable dry machining. The effect of cutting speed, feed rate, and depth of cut on machining performance has been evaluated for both conditions. The machining time and surface roughness were found to be lower in dry machining compared to flood coolant machining. The tool wear was found to be unpredictable, and no significant difference was observed for dry and coolant machining. In a comparison of all the parameters, sustainable dry machining was found to provide better performance in machining Ti-6Al-4V. This study also investigated the machinability of Ti-6Al-4V using coated and uncoated tungsten carbide tools under dry conditions. Tool wear is a serious problem in the machining of titanium alloys in dry conditions. Heat dissipation from the toolworkpiece interface a difficult challenge in dry machining, resulting in the alloying of the workpiece to the tool surface. Dry machining with the coated tool was comparatively faster, and resulted in less tool wear than uncoated tools. Using the Titanium aluminum nitride TiAlN coated carbide tool during dry machining provided a smoother surface finish with lower average surface roughness. The conclusion, therefore, is that the tool coating was found to be effective for the dry machining of titanium alloys.

The goal of my doctoral work is to understand how proteins involved in vesicle trafficking contribute to proper animal development. To understand aspects of this process, I studied how two vesicle trafficking proteins, Liquid facets(Lqf)/epsin1 and D-Epsin-Related, affect Drosophila eye development. I determined that Lqf, an endocytosis protein, together with Fat facets (Faf), a deubiquitinating enzyme, regulate the Notch and Delta signaling in the developing Drosophila eye. Notch signaling pathway is used in most developmental processes and is dependent on its ligand Delta. Faf deubiquitinates Lqf in the signaling cells, thereby increasing Lqf protein levels and also levels of Delta endocytosis. This event is necessary for Notch activation in neighboring cells. Lqf probably works in concert with the E3 ubiquitin ligase Neuralized (Neur), which ubiquitinates Delta. These conclusions are consistent with a relatively new model describing an obligate role for endocytosis in the signaling cells to effect activation in neighboring cells. To understand how Lqf functions mechanistically in this process, I performed a structure/function analysis of the Lqf protein. Lqf proteins with strategic deletions of certain functional domains were tested for their ability to function in vivo. The major result of these experiments is that the N-terminal ENTH domain of Lqf and a protein without the ENTH domain each retain significant activity. This suggests that Lqf has two functions: the ENTH domain function and the ENTH-less function. These data are in contrast with the most popular model suggesting that ENTH-less epsins are non-functional proteins. I present possible models for how ENTH-less epsins may retain function. The final part of my thesis focuses on D-Epsin-Related (D-Epsin-R) protein. I showed that D-Epsin-R is a Golgi protein, like its homologs. Surprisingly, D-Epsin-R ENTH domain is not required for function because an ENTH-less D-Epsin-R can substitute for endogenous D-Epsin-R. Also, D-Epsin-R has essential and probably specific developmental roles in the eye as D-Epsin-R mutants exhibit impaired cell growth. This work suggests that epsins are specific components of certain developmental pathways. / text

<p>This licentiate thesis comprises two complementary studiesdealing with the sheet-fed offset printing of paper. The firststudy addresses the further development of a practical methodto acoustically monitor and analyse the film splitting ofoffset inks. This method was tested on laboratory printingequipment, specifically monitoring the continuous ink splittingin the nip of an IGT ink distribution unit and the short-timeink splitting in the inked print disc-paper nip of the printingunit of an ISIT instrument. The study verified that the inksplitting component of the acoustic signal contributes to thehigher frequency range (10-20 kHz) of the audible spectrum, andcan thus be separated from the lower frequency machine noise.Furthermore, the film splitting component is sensitive tochanges in the ink and printing conditions, thus enabling itsuse in probing the fundamental mechanisms occurring during inktransfer and also suggesting its applicability fornon-intrusive monitoring of industrial printing presses. Anincrease in film thickness during ink distribution correspondsto an increased acoustic power, with the exception of very lowink amounts, which give reduced acoustic emission due to alubricating effect. The effect of the presence of fountainsolution was simulated by adding emulsion-forming, butnon-evaporative, ethylene glycol. This produces an increase inacoustic power at low amounts, due to resistance to glycol dropdeformation, followed by a decrease at higher amounts owing toexcess glycol lining the rolls. During test printing on paper,increasing ink amounts also display an increased acousticresponse.</p><p>The second study further developed a theoretical model toexplain and predict the evolution of ink tack in terms of inksetting directly after offset printing on coated paper. Asmeasured by the ISIT, the tack of the printed ink rises duringshorter time periods, attains a maximum, and then falls atlonger times. The proposed model described how the ink tack,characterised by the impulse during disc pull-off, dependsdynamically on the viscoelastic properties of the ink, thecontact with paper and disc, and the flow geometry. The inksetting was modelled as a diffusion-limited transport of theoil vehicle through the ink film and into the pores of thecoated paper. The coupling of the tack and setting models,compared to the ISIT experimental measurements, then provided adiffusion coeffcient for ink setting during the tack riseperiod. This coeffcient decreases with time, and increasinglyrapidly with decreasing ink amounts due to theconcentration-dependent diffusion. For an accurate descriptionthe elasticity and adhesion effects also have to be considered,at least for explaining the tack fall period.</p>

Voltammetric and spectroelectrochemical results are presented for the one-electron reduction of n-heptyl viologen on clean and silane-modified tin oxide, and on ion-beam modified, indium-tin oxide metallized plastic optically transparent electrodes (ITO MPOTE) surfaces. The use of viologens (dialkyl and diaryl 4,4' bipyridium compounds) in redox chromic displays is well known with a number of papers and patents discussing their use. The ability to vary the coloration rates of the electrochromic reaction of these compounds can be strongly influenced by the state of the electrode surface. Potential-step experiments, where the electrode potential is controlled at low overpotentials, has shown that the viologen reduction occurs through a nucleation process. The work here indicates that an "instantaneous nucleation" model appears to be the favored pathway for the n-heptyl viologen reaction. Chronoabsorptometric analysis of the nucleation process is made possible by monitoring the strongly absorbing viologen cation radical. Chronoabsorptometric data can be used to calculate the nucleation site density on an electrode surface. On silane-modified and ion-beam modified electrode surfaces, a more preferred nucleation site is found for the deposition of the first monolayers of viologen. Through the attachment of a silane or the ion-beam modification of an ITO metallized plastic film (ITO MPOTE), a nonpolar layer is created adjacent to the electrode surface. Prior to electrochemical reduction the n-heptyl viologen dication is partioned and concentrated into this nonpolar layer. The effect is a preconcentration of the viologen next to the electrode surface resulting in a fixed number of nucleation sites and an enhancement of the nucleation rate.

No description available.