Processing-Structure-Performance Relationships in Fused Filament Fabricated Fiber Reinforced ABS for Material Qualification

This dissertation uses the processing-structure-performance relationships to elucidate future needs in qualification of materials manufactured by fused filament fabrication and also introduces a previously unused testing method for the determination of fracture toughness in these materials. Fused filament fabrication (FFF) is an additive manufacturing technique that utilizes the layering of deposited molten plastic in two dimensional shapes to create three dimensional objects. This technique has gained traction over the past two decades as a disruptive manufacturing technology that promises many benefits. In order for FFF to truly be a staple in manufacturing spaces across the world for the production of end-user parts, standardization of testing procedures for the qualification of FFF specific materials must take place. Adjusting standards for qualification must occur with analysis in ultimate tensile strength, response to environmental conditions, and the fracture behavior of these parts. In Chapter 1, a comprehensive analysis of the current state of the art in fracture of FFF parts is presented and discussed. Discussed in this section are the rheological specific phenomena that govern the polymer chain physics at interfaces and within deposited beads. This is tied to the fracture strength and the current questions in part behavior. In chapter 2, a commonly used tensile testing standard is explored and tested on fiber reinforced acrylonitrile-butadiene-styrene (ABS). Due to the complex manufacturing process, new naming standards and testing recommendations are made and the influence of part production methodologies and processing parameters on ultimate tensile strength are explored. The response of fiber reinforced and non-reinforced ABS in environmental conditioning is tested and discussed in chapter 3, where specimens were exposed to heat and moisture then tested in tension. Chapter 4 introduces a unique testing specimen to the FFF literature to obtain multiple fracture modes. Through this test specimen, the nature of the material as a laminate or as a porous homogeneous material is also explored and documented

Proteinase-activated receptor-2 modulates human macrophage differentiation andeffector function

Proteinase-activated receptor-2 (PAR-2) was shown to influence immune regulation; however, its role in human macrophage subset development and function has not been addressed. Here, PAR-2 expression and activation was investigated on granulocyte macrophage (GM)-CSF(M1) and macrophage (M)-CSF(M2) macrophages. In both macrophages, the PAR-2-activating peptide, SLIGKV, increased PAR-2 expression and regulated TNF-α and IL-10 secretion in a manner similar to LPS. In addition, HLA-DR on M1 cells also increased. Monocytes matured to an M1 phenotype in the presence of SLIGKV had reduced cell area, and released less TNF-α after LPS challenge compared with vehicle (P < 0.05, n = 3). Cells matured to an M2 phenotype with SLIGKV also had a reduced cell area and made significantly more TNF-α after LPS exposure compared to vehicle (P < 0.05, n = 3) with reduced IL-10 secretion (P < 0.05, n = 3). Thus, PAR-2 activation on macrophage subsets regulates HLA-DR and PAR-2 surface expression, and drives cytokine production. In contrast, PAR-2 activation during M1 or M2 maturation induces altered cell morphology and skewing of phenotype, as evidenced by cytokine secretion. These data suggest a complex role for PAR-2 in macrophage biology and may have implications for macrophage-driven disease in which proteinase-rich environments can influence the immune process directly

Effects of ethanol on membrane lipids III. Quantitative changes in lipid and fatty acid composition of nonpolar and polar lipids of mouse total liver, mitochondria and microsomes following ethanol feeding

The effects of ethanol on the total, nonpolar, and polar lipids of whole liver, mitochondria, and microsomes have been evaluated. Differences in the fatty acid composition of various lipid subclasses have been compared in control and ethanol treated mice. On the whole polyunsaturated fatty acids, especially arachidonic (20∶4) and docosahexaenoic (22∶6), were found to decrease. The significance of an enzymatic mechanism vs. a peroxidative mechanism to explain the results is discussed. Decreases also were observed in the ratios of arachidonate/linoleate following ethanol feeding. These changes are thought to be associated with decreases in the activity of the chain elongation‐desaturation system.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141242/1/lipd0722.pd

Handling disruptions in a network with cross-docking

Cross-docking (CD) is a commonly used technique to consolidate freight for more efficient delivery to customers; CD is continuing to see increased use by companies. Synchronization of inbound and outbound freight is clearly critical to operations and so is having the cross-dock able to support the freight flow with available doors and material handling equipment. The latter is particularly important when there is a disruption in the inbound freight. One delayed truck can impact several outbound trucks. A methodology is proposed to address explicitly both the scheduling of trucks and material handling within the CD. Two models are proposed – one for routing inbound and outbound trucks and the other to schedule the cross-dock. Results from each model when run separately are presented as well as results from when the two models are run iteratively

Natural occurrence of S-alkyl glycerol ethers in ehrlich ascites cells

1. 1. S-alkyl glycerol ethers were isolated by thin-layer chromatography from the total lipids of Ehrlich ascites cells following reduction with vitride.2. 2. Gas-liquid chromatography of the isopropylidene derivatives showed the principal component to be 16:0 (83%) with lesser amounts of 18:1 (14%) and 18:0 (2%).3. 3. Quantitative analysis yielded values of about 2 [mu]moles/100 mg lipid for the isolated thioethers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22700/1/0000254.pd

Endothelium-derived contraction in a model of rheumatoid arthritis is mediated via angiotensin II type 1 receptors

A role for endothelium-derived constricting factors (EDCF), and the angiotensin II type 1 receptor (AT1R) pathway, in the vascular impairment found in the rat Freund's complete adjuvant (FCA)-model of rheumatoid arthritis (RA) was examined. FCA arthritis was induced in rats±losartan. Vehicle-treated rats served as controls. Knee-joint swelling and red blood cell (RBC) aggregation were measured as indicators of inflammation and endothelium reactivity assessed by response to acetylcholine (ACh) on aortic rings. Results show that knee-joint swelling and RBC aggregation were elevated in the FCA+vehicle group and restored to control levels in the FCA+losartan-treated animals. ACh-induced relaxation of aortic rings taken from FCA+vehicle animals was significantly impaired compared to vehicle-controls and this vasoreactivity was restored to control levels in the FCA+losartan-treated group. Further examination of aorta from the FCA+vehicle animals revealed an EDCF that was reliant on cyclooxygenase-2 (but not cyclooxygenase-1), generation of superoxide anion generation (but not hydrogen peroxide) and activation of thromboxane-prostanoid receptor. Losartan administration in vivo or ex vivo (to aortic rings) prevented the generation of the EDCF. In summary, this is the first evidence of an EDCF in a model of RA and identifies this mechanism as potentially significant in the cardiovascular disorder associated with the disease