The objective of this research is to evaluate the influence of the factors identified by the Johnson, Kendall and Robert’s theory that affect the strength of the detachment force necessary to remove a particle of contaminant from a surface, and the roughness of the surface in which the contaminant is present, on predicting the efficiency of removal of loose contamination. Two methods were used to reach this objective: the first method consisted of quantifying the contamination by weight and the second method of quantifying the contamination by counting alpha and gamma particles. As a result, it was determined that for particles of 5 μm, the interaction between contaminant-wipe and contaminant-surface were significant. However, for particles between 37-149 μm, the contaminant-surface interaction was the only significant interaction affecting the amount of contamination removed. The results obtained were already used at a contaminated site, confirming the prediction of contamination removed

Abstract Application of Argon Plasma Technology to Hydrophobic and Hydrophilic Microdroplet Generation in PDMS Microfluidic Devices Brennan Graham Microfluidics has gained popularity over the last decade due to the ability to replace many large, expensive laboratory processes with small handheld chips with a higher throughput due to the small channel dimensions [1]. Droplet microfluidics is the field of fluid manipulation that takes advantage of two immiscible fluids to create droplets from the geometry of the microchannels. This project includes the design of a microfluidic device that applies the results of an argon plasma surface treatment to polydimethylsiloxane (PDMS) to successfully produce both hydrophobic and hydrophilic surfaces to create oil in water (O/W) and water in oil (W/O) microdroplets. If an argon plasma surface treatment renders the surface of PDMS hydrophilic, then O/W microdroplets can be created and integrated into a larger microdroplet emulsion device. The major aims of this project include: (1) validating previously established Cal Poly lab protocols to produce W/O droplets in hydrophobic PDMS microdroplet generators (2) creating hydrophilic PDMS microdroplet generators (3) making oil in water droplets in hydrophilic PDMS microdroplet generators (4) designing a multilayer microfluidic device to transfer W/O droplets to a second hydrophilic PDMS microdroplet generator v W/O droplets were successfully created and transferred to a second hydrophilic PDMS device. The hydrophilic PDMS device also produced O/W droplets in separate testing from the multilayered microfluidic PDMS device. The ultimate purpose of this project is to create a multilayer microdroplet generator that produces water in oil in water (W/O/W) microdroplet emulsions through a stacked device design that can be used in diagnostic microdroplet applications. Thesis Supervisor: Dave Clague Title: Professor of Biomedical Engineering

Clinical evidence indicates a higher incidence of peripheral arterial occlusive disease and associated likelihood of critical limb ischemia in women, as well as worse prognosis and decreased survival post myocardial infarction. Therefore, understanding the possible differences in underlying vascular compensation mechanisms is crucial. With arterial occlusions, necrosis and tissue injury can be naturally mitigated by the collateral circulation, improving patient prognosis. Previous sex-comparison studies describing differences in vascular remodeling are inconsistent. Therefore, the aim of this study was to describe the effect of arterial occlusion on collateral remodeling in healthy male and healthy reproductive-stage female mice. At 7 days following femoral artery ligation in C57Bl/6 and BALB/c mice, there were no sex-related differences in functional ambulatory recovery. There were no sex-related differences in mechanoadaption indicators in the collateral stem- vascular smooth muscle cell (VSMC) length and overlap, with the exception of longer smooth muscle cells in male C57Bl/6 mice, VSMC lengths 329 ± 19 verses 288 ± 13 μm, male and female. Collateral midzone luminal and abluminal diameters, as well as wall thicknesses were not different between sexes. As comprehensive sex-specific differences were not captured in our specific investigation of arteriogenesis, an evaluation of microvascular remodeling in the ischemic zone and collateral vasodilation would be of interest, as would evaluating arteriogenesis following oophorectomy with estrogen depletion. The determination of any underlying mechanistic sex-specific differences could be the foundation for which targeted therapeutics are developed, which will be crucial for closing the prognosis gap between men and women in the global treatment of peripheral arterial occlusive disease.

The role of cytokines and cell behavior and viability with respect to bone remodeling and bone behavior is an exciting area of orthopedic research. The purpose of this study was to investigate the relationships between BMP antagonist expression and osteocyte density, lacunar densities and osteocyte viability in cortical bone. Samples of unloaded tibial bone obtained from six C57Bl/6 mice were immunohistochemically stained for gremlin and noggin expression and also underwent methyl green staining to determine osteocyte presence. Bone sections were divided into four quadrants (cranial, caudal, medial and lateral) and three regions (proximal, mid shaft and distal), followed by analysis across these quadrants and regions. The results showed matching regional differences in gremlin expression with regional variations in osteocyte density, lacunar density, and osteocyte viability. These variations were supported by positive correlations found via regression analysis. Regression analysis also showed marginal negative correlations between noggin expression and osteocyte density and osteocyte viability, supported by regional ANOVA results. Further research on loaded bone samples is needed if the relationship between these BMP antagonists and osteocyte densities are to be fully explained with respect to the bone remodeling process.

Recently, a constituent based cartilage growth finite element model (CGFEM) was developed in order to predict articular cartilage (AC) biomechanical properties before and after growth. Previous research has noted limitations in the CGFEM such as model convergence with growth periods greater than 12 days. The main aims of this work were to address these limitations through (1) implementation of an exact material Jacobian matrix definition using the Jaumann-Kirchhoff (J-K) method and (2) quantification of elastic material parameters based upon research findings of the Cal Poly Cartilage Biomechanics Group (CPGBG). The J-K method was successfully implemented into the CGFEM and exceeded the maximum convergence strains for both the “pushed forward, then differentiated” (PFD) and “differentiated, then pushed forward” (DPF) methods, while maintaining correct material stress responses. Elastic parameters were optimized for confined compression (CC), unconfined compression (UCC), and uniaxial tension (UT) protocols. This work increases the robustness of the CGFEM through the J-K method, as well as defines an accurate starting point for AC growth based on the optimized material parameters.

This project encompasses the implementation of a computational model to simulate the microfluidic separation of like-charged particles in a continuous flow environment. By accomplishing this task the model can be used to optimize future fractionations by tailoring the process parameters to the properties of the target particles. The primary goal of this project is to develop a vectorized code within Matlab® that captures a sufficient quantity of the physics in separations to assist with the optimization and design of microfluidic systems. This project differs from other computational models in that it utilizes a personal computer to run the simulation in an optimized format rather than utilizing a highly parallelized system for the computing. Based on previous literature from computational models of fluid-particle systems a model was developed to simulate the separation process. Computational experiments of separation processes were conducted with this model to validate the simulation and to investigate the impacts of microfluidic fractionation parameters on the purity and yield of like charged particles in a continuous flow environment. By adapting the input parameters the separation results can be customized for the particles in the sample. The implementation and use of this this model can improve the efficiency of separation processes.

Mammary epithelial cells are highly efficient secreting cells. With genetic engineering, the uses of these cells could be endless. Research is being conducted on these cells to determine their full potential to the biotech industry. This paper investigates whether bovine epithelial mammary cells can survive in glutaraldehyde-treated gelatin tubes in an operating bioreactor. Many bioreactors were developed and tested to suit the needs of the cells. Procedures were created and carried out to ensure sterility of the bioreactors. Bovine mammary epithelial cells were implanted in the bioreactors and samples of their growth were taken over time.

ABSTRACT A Study of Osteocyte Apoptosis by Region and Quadrant in Murine Cortical Bone Jessica Kristen Chan Osteocytes undergo apoptosis to spatially and temporally initiate bone remodeling. This study investigates the distribution of apoptotic osteocytes within different quadrants and regions of cortical bone and compares the frequency of osteocyte apoptosis to regional factors associated with bone remodeling. Specifically, the quantity of apoptosis was compared to levels of the bone morphagenic protein antagonists noggin and gremlin. Samples of unloaded right tibial bone obtained from C57/Bl/6 mice underwent TUNEL staining for apoptotic osteocytes and were counterstained with methyl green to detect osteocyte viability. Cross sectional areas of bone were divided into four quadrants (cranial, caudal, medial, and lateral) and three regions (proximal, midshaft, and distal) for analysis. Densities and percentages of osteocytes were measured within each area. While the results show that there were no differences among quadrants, regional variations were found in osteocyte apoptosis. A significantly higher density of apoptotic osteocytes was found in the midshaft region which also displayed higher levels of BMP antagonists. Using regression analysis, a positive linear relationship between apoptotic osteocytes and gremlin was established while noggin showed a negative linear correlation for the percentage of apoptotic osteocytes. Further studies are needed to observe the distribution of apoptotic osteocytes within loaded bone to confirm the exact relationship between osteocyte apoptosis and bone remodeling. Keywords: osteocyte apoptosis, bone remodeling

ABSTRACT Characterization Of Raw Milk Fouling On Plate-Type Heat Exchangers Using Different Alloys And Cow PhenotypeS Stephen Ernest Nelson Milk and other dairy products are widely used in many households today. Milk is a popular beverage that is seen as a healthy alternative to other synthetic beverages such as soda pop and other sugar based drinks. It became law that milk, and milk products are pasteurized before its release to the general public (FDA 2003). Pasteurization is a thermal process where the intent is to lower the concentration of microorganisms in the milk to render it safe to drink with heat (Bansal and Chen 2006). With all the thermal processing of the raw milk, this leads to thermal efficiency degradation of the heat exchangers used to pasteurize the milk (Bansal and Chen 2006) due to direct fouling of the heating surface. The buildup of organic and inorganic matter onto a metal surface from the constant heating of the milk on a stainless steel surface is called fouling. The exact mode on which the fouling layers nucleate and grow is unknown by the date of this writing. Milk fouling has been around as long as the pasteurization process. (Visser and Jeurnink 1997) Fouling rate is related to a function of variables. Fouling rate is a function of milk type, time, and temperature, age of the milk, seasonal variations, process equipment design and more. The main consensus of milk fouling initiation is that of the whey protein b-Lactoglobulin which constitutes about 0.32% in whole milk (de Jong 1997; Bansal and Chen 2005a; Bansal and Chen 2006). Table III shows the general compositions of the constituents in milk. In order to look for dependence between milk phenotypes and heated surface alloys, a design of experiment (DOE) was made. The experiment used three types of milk phenotypes to test for fouling differences. Also, four alloy compositions were also tested against the milk phenotypes. This produced a three by four matrix of variable combinations or 3x4 factorial design. It was hoped that these combinations will show a certain, but repeatable process condition which will produce lower fouling rate versus the control milk type. The milk phenotypes used in this experiment are phenotype AB-AB (control), AB-AA, and AB-BB. The phenotype of label before the hyphen was the k-casein phenotype, the label after the hyphen represented the b-Lacto globulin phenotype. The four metal types tested were stainless steel 304 (control), stainless steel 316, stainless steel 430, and titanium 6V 4Al. It was not feasible to change out the plates in the pilot scale milk pasteurizer at the pilot plant at the Dairy Products Technology Center (DPTC), or to make special replacement plates that exposed each metal to be tested on a single heat exchanger plate (AOAC-c 1995). The manufacturing of a complete laboratory scale milk pasteurizer for the study of milk fouling on metal plates proved to be very successful. The model flow cell heat exchanger produced high enough quality of milk foulant on the test coupons in comparison to the large scale fouling layers found in full scale dairy heat processing equipment. Although generally speaking, there was not a significant technology breakthrough of using different alloys as the material for the plates in milk pasteurizer heat exchangers, a method of creating the milk fouling layer on a smaller scale can be very useful in future works studying milk fouling. The titanium alloy showed a significantly lower fouling rate, this was probably mostly due to the highly passivated surface of the Titanium. It was also seen that the actual breed of cow could have played a significant role in fouling. The new FCHE model was produced to show the viability of creating a biofilm or milk fouling layer on any material provided that it is rigid enough. Microorganisms were also briefly studied on the foulant layer that was produced with the flow cell. This new approach should provide a basis for new and more advanced research of the mechanisms and nature of milk fouling in heat processing equipment.

The onset of osteoporosis caused by aging, disease states, and post-menopausal conditions significantly impacts patient quality of life, required healthcare funding, personal autonomy losses from increased fracture risk and the subsequent corrective surgery. Research has indicated that osteocyte apoptosis may be a key parameter in bone remodeling, raising the possibility of remodeling rate modulation for the mitigation of bone mass resorption. By developing therapies that target osteocyte apoptosis, it may be possible to prevent undesired bone remodeling activity while maintaining a healthy balance between damage formation in the form of microcracks induced by the strain environment and the removal of damaged bone facilitated by resorbing BMUs, resulting in the preservation of bone mass. This preservation in turn results in a decreased risk of bone fracture. The purpose of the current study was to develop a computational model to predict bone density changes from empirical osteocyte apoptosis data. This was achieved by developing a simulation that correlates osteocyte apoptosis with activation frequency and mechanical stimulus, two key bone remodeling parameters. The results of the simulation show that it is possible to use osteocyte apoptosis to predict remodeling and the resulting bone porosity changes. Instances of increased osteocyte apoptosis occurred simultaneously with increases in porosity, and under-loaded force conditions were more deleterious to bone porosity then overload associated with heavy exercise, which agrees with previous models.