Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

Thesis (M.S.)--Brigham Young University. Dept. of Technology, 2004. / Includes bibliographical references (p. 191-195).

Deficiencies in biotreatment due to uncontrolled growth of filamentous microorganisms is a problem for wastewater plants worldwide. The project was assigned with the task of reducing the growth of filamentous bacteria at the paper mill SCA Munksund. 12 bacteria and 1 fungi species were presented to the project as problematic due to their filamentous properties. Operating parameters affecting filamentous growth was examined and presented. The information gathered showed that a decrease in filamentous growth for 5 especially problematic bacteria could possibly be achieved by raising the DO, increasing the concentration of nutrients and decreasing the sludge age. Other parameters affecting the growth of filamentous bacteria, such as pH, temperature and F/M were found to be too diverse among the examined species. Alternative solutions not focused on finding optimal operating parameters was also investigated. Promising results were treatment using a feast-famine approach, installation of an anaerobic selector and ozonation of return sludge. A statistical analysis was also performed on operating data. Methods used were Principal component analysis, Clustering and Logistic regression. These were used as a proof of concept rather than providing meaningful data for an operating window.

Background and aims: It is known that smooth muscle possesses substantial mechanical plasticity in that it is able to adapt to large changes in length without compromising its ability to generate force. It is believed that structural malleability of the contractile apparatus underlies this plasticity. There is strong evidence suggesting that myosin thick filaments of the muscle are relatively labile and their length in vivo is determined by the equilibrium between monomeric and filamentous myosin. The equilibrium in turn is governed by the state of phosphorylation of the 20-kD regulatory myosin light chain (MLC20, or RLC). It is known that phosphorylation of the myosin light chain favors formation of the filaments; it is not known how the light chain phosphorylation affects the lability of the filaments. The major aim of this thesis was to measure the mechanical integrity of the filaments formed from purified myosin molecules from bovine airway smooth muscle, and to determine whether the integrity was influenced by phosphorylation of the myosin light chain. Methods: Myosin was purified from bovine trachealis to form filaments, in ATP containing zero-calcium solution during a slow dialysis that gradually reduced the ionic strength. Sufficient myosin light chain kinase and phosphatase, as well as calmodulin, were retained after the myosin purification and this enabled phosphorylation of RLC within 20-40 s after addition of calcium to the filament suspension. The phosphorylated and non-phosphorylated filaments were then partially disassembled by ultrasonification. The extent of filament disintegration was visualized and quantified by atomic force microscopy. Results: RLC phosphorylation reduced the diameter of the filaments and rendered the filaments more resistant to ultrasonic agitation. Electron microscopy revealed a similar reduction in filament diameter in intact smooth muscle when the cells were activated. Conclusion: Our results suggest that RLC phosphorylation is a key regulatory step in modifying the structural properties of myosin filaments in smooth muscle, where formation and dissolution of the filaments are required in the cells’ adaptation to different cell length. / Medicine, Faculty of / Medicine, Department of / Experimental Medicine, Division of / Graduate

As the genetic causes of Hypertrophic Cardiomyopathy (HCM) have become widely recognized, considerable lag in the development of targeted therapeutics has limited interventions to symptom palliation. This is in part due to an oft-noted finding that similar point mutations within myofilament proteins are known to cause differential disease severity, highlighting the need to understand disease progression at the molecular level. One commonly described pathway in HCM progression is calcium homeostasis dysregulation, albeit little is understood about disruption of the pathway. This dissertation investigated the calcium homeostasis of two clinically relevant murine models of HCM expressing similar point mutations within myofilament proteins. A mutation-specific alteration in the calcium dissociation rate from the cardiac myofilament is proposed to as a primary mechanism of down-stream calcium disruption. Two modes of intervention in down-stream calcium homeostasis were tested to as a means of improving directed therapies in HCM progression. The clinically-utilized diltiazem hydrochloride, an L-type calcium channel blocker, revealed mutation-specific symptom palliation but an inability to target within the disease mechanism itself. Due to this insufficient response to diltiazem, we investigated the role of the calcium-dependent kinase, CaMKII, and its persistent (autonomous) activation resulting from calcium dysregulation. Partial inhibition of the autonomous activation of the kinase was shown to improve functional and morphological indices of failure in calcium-dependent HCM progression. Thus, we conclude a myofilament-linked derangement in calcium homeostasis that potentiates aberrant activation of CaMKII. Moreover, we position the kinase as a nodal point in disease progression and a potential therapeutic target for early, robust management of HCM in the clinical population.

The essence of this work is to summarize the knowledge about 3D printing, especially with FDM technologies. Create an overview of used FDM printing materials, identify their advantages and disadvantages, technical parameters and usability. Another purpose of the thesis is to examine the print quality and its problems and specify types of surface finishes for selected materials. The content also includes remote control and monitoring of the 3D print process using the Raspberry Pi microcomputer and the print server named Octoprint.

Termoplaster används i en mängd olika produkter världen över. En starkare termoplast kan leda till att en mindre mängd material behövs för att bibehålla samma styrka i en produkt. En lättare produkt kan exempelvis leda till minskad bränsleförbrukning vilket är positivt i avseende för miljön, socialt och ekonomiskt.  Ett möjligt sätt att tillverka en starkare termoplast skulle kunna vara att förstärka den med cellulosafibrer. FineCell Sweden AB tillverkar cellulosafibrer i mikrostorlek genom en miljövänlig och energieffektiv kemisk process, vilket resulterar i en ekologiskt hållbar produkt. Nya tillverkningsmetoder som additiv tillverkning tillåter nya möjligheter för de former som kan tillverkas med termoplaster. Det är intressant att undersöka om det går att använda en cellulosaförstärkt termoplast till 3D-printning. Detta examensarbete har fokuserat på extrudering av mikrocellulosaförstärkt filament, och hur olika tillverkningsprocesser påverkar kvalitén och hur de mekaniska egenskaperna påverkas. Resultatet visar att mikrocellulosan i vissa fall kan ge ökad elasticitetsmodul, och att torkning och hantering av cellulosan innan extrudering är avgörande för egenskaperna, då eventuell fukt leder till porer vilka påverkar de mekaniska egenskaperna negativt.  I vidare arbete skulle fler materialegenskaper för det tillverkade filament vara intressant att undersöka. Det skulle vara intressant att tillverka filament med en ”Twin-screw” extruder, då det kan fördela fibrerna och skjuva till mindre storlek. Det skulle även vara intressant att undersöka mikrocellulosaförstärkning med andra typer av tillverkningsmetoder, högre fiberandelar och andra sorters termoplaster. / Thermoplastics are used in a variety of products worldwide. A stronger thermoplastic could lead to a smaller amount being needed to maintain the same strength in a product. A lighter product can, for example, lead to reduced fuel consumption, which is positive for the environment, socially and economically. One possible way to make a stronger thermoplastic could be to reinforce it with cellulose fibers. FineCell Sweden AB manufactures micro-sized cellulose fibers through an environmentally friendly and energy-efficient chemical process, which results in an ecologically sustainable product. New manufacturing methods such as additive manufacturing allows new possibilities for the shapes that can be manufactured with thermoplastics. It is interesting to investigate whether it is possible to use a cellulose-reinforced thermoplastic for 3D-printing. This master thesis has focused on the extrusion of microcellulose-reinforced filament and how different manufacturing methods affect the quality and how the mechanical properties are affected. The results show that the microcellulose can in some cases give an increased modulus of elasticity and that drying and handling of the cellulose before extrusion is decisive for the properties, as any moisture leads to pores which adversely affect the mechanical properties. In further work, more material properties of the manufactured filament would be interesting to investigate. It would be interesting to make filaments with a "twin-screw" extruder, as it can distribute the fibers and shear to a smaller size. It would also be interesting to investigate microcellulose amplification with other types of manufacturing methods, higher fiber ratios and other types of thermoplastics.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Metal 3D printing typically requires high energy laser or electron sources. Recently, 3D printing using metal filled filaments becomes available which uses PLA filaments filled with metal powders (such as copper, bronze, brass, and stainless steel). Although there are some studies on their printability, the detailed study of their sintering and characterizations is still missing. In this study, the research is focused on 3D printing of bronze filaments. Bronze is a popular metal for many important uses. The objectives of this research project are to study the optimal processing conditions (like printer settings, nozzle, and bed temperatures) to print bronze metal filament, develop the sintering conditions (temperature and duration), and characterization of the microstructure and mechanical properties of 3D printed specimens to produce strong specimens. The thesis includes three components: (1) 3D printing and sintering at selected conditions, following a design of experiment (DOE) principle; (2) microstructure and compositional characterizations; and (3) mechanical property characterization. The results show that it is feasible to print using bronze filaments using a typical FDM machine with optimized printing settings. XRD spectrums show that there is no effect of sintering temperature on the composition of the printed parts. SEM images illustrate the porous structure of the printed and sintered parts, suggesting the need to optimize the process to improve the density. The micro hardness and three-point bending tests show that the mechanical strengths are highly related to the sintering conditions. This study provides important information of applying the bronze filament in future engineering applications.

No description available.