This research investigated biofluid lubrication related to artificial joints using tribological and rheological approaches. Biofluids studied here represent two categories of fluids, base fluids and nanostructured biofluids. Base fluids were studied through comparison of synthetic fluids (simulated body fluid and hyaluronic acid) as well as natural biofluids (from dogs, horses, and humans) in terms of viscosity and fluid shear stress. The nano-structured biofluids were formed using molecules having well-defined shapes. Understanding nano-structured biofluids leads to new ways of design and synthesis of biofluids that are beneficial for artificial joint performance. Experimental approaches were utilized in the present research. This includes basic analysis of biofluids’ property, such as viscosity, fluid shear stress, and shear rate using rheological experiments. Tribological investigation and surface characterization were conducted in order to understand effects of molecular and nanostructures on fluid lubrication. Workpiece surface structure and wear mechanisms were investigated using a scanning electron microscope and a transmission electron microscope. The surface topography was examined using a profilometer. The results demonstrated that with the adding of solid additives, such as crown ether or fullerene acted as rough as the other solids in the 3-body wear systems. In addition, the fullerene supplied low friction and low wear, which designates the lubrication purpose of this particular particle system. This dissertation is constructed of six chapters. The first chapter is an introduction to body fluids, as mentioned earlier. After Chapter II, it examines the motivation and approach of the present research, Chapter III discusses the experimental approaches, including materials, experimental setup, and conditions. In Chapter IV, lubrication properties of various fluids are discussed. The tribological properties and performance nanostructured biofluids are discussed in Chapter V, followed by summary and conclusions in Chapter VI.

Proteomic technology has been increasingly incorporated into agricultural research, as characterization of proteomes can provide valuable information for potential biomarkers of health and physiological status of an animal. As dairy cattle are a dominant production animal in the USA, their biofluids such as milk, blood, urine, and rumen fluid have been examined by proteomic analysis. The research outlined herein was performed to further characterize the dynamics of specific proteomes and relate them to dairy cattle physiology. The first experiment evaluated the diurnal dynamicity of the rumen metaproteome in Holstein dairy cattle. Rumen fluid was collected from three mid to late lactation multiparous dairy cattle (207 ± 53.5 days in milk) at three time points relative to their first morning offering of a total mixed ration (TMR) (0 h, 4 h, and 6 h after feeding). Samples were processed and labeled using Tandem Mass tagging before being further fractionated with a high pH reversed-phase peptide fractionation kit. Samples were analyzed by LC-MS/MS and statistically analyzed for variations across hour of sampling using the MIXED procedure of SAS with orthogonal contrasts. A total of 242 proteins were characterized across 12 microbial species, with 35 proteins identified from a variety of 9 species affected by time of collection. Translation-related proteins were correlated positively with increasing hour of sampling while more specific metabolic proteins were negatively correlated with increasing hour of sampling. Results suggest that as nutrients become more readily available, microbes shift from conversion-focused biosynthetic routes to more encompassing DNA-driven pathways. The second experiment aimed to characterize the milk fat globule membrane (MFGM) proteomes of colostrum and transition milk for comparison from multi- (n = 10) and primiparous (n = 10) Holstein dairy cattle. Samples were collected at four timepoints post-partum (milkings 1, 2, 4, and 14). After isolation of the protein lysates from the MFGM, proteins were labeled using Tandem Mass tagging and analyzed using LC-MS/MS techniques. Protein identification was completed using MASCOT and Sequest in Proteome Discoverer 2.2. Protein abundance values were scaled and analyzed using the MIXED procedure in SAS to determine the effect of parity, milking number, and parity x milking number, and the adaptive false-discovery rate (FDR)-adjusted P values were determined using the MULTTEST procedure of SAS. There were 104 proteins identified within the MFGM. Statistical analysis revealed that 44.2% of proteins were affected by parity, 70.2% by milking number, and 32.7% by the variable of parity x milking number. There was a two-fold difference in calcium sensing S100 proteins in cows differing in parity possibly due to the multiparous mammary gland being more adapted to the physiological demand of lactation or the lesser requirement of calcium in primiparous cows because of a lower production rate.

Tratamentos termoquímicos são processos utilizados pela indústria em componentes de sistemas mecânicos com o intuito de melhorar as suas propriedades superficiais, em especial o desempenho em desgaste. Esses sistemas são utilizados em conjunto com lubrificantes em máquinas e equipamentos dos mais variados tipos. Normalmente os lubrificantes mais usados em função do seu bom desempenho, são de base mineral. Entretanto, há vários estudos propondo o uso de lubrificantes de base vegetal mas pouco se conhece da interação da superfície com esses biofluidos. Sendo assim é importante se identificar como uma superfície tratada ou não, irá interagir com os diferentes tipos de lubrificantes. Dentro deste escopo, este trabalho se propõe a comparar a resposta tribológica de superfícies tratadas termoquimicamente ou não quando lubrificada com biofluidos e com óleos derivados de petróleo. O estudo foi realizado por meio do método \"ball-cratering test\". Como corpos de prova, foram utilizados pastilhas de aço AISI 4140 submetidas aos tratamentos termoquímicos de nitretação e nitrocementação e também sem tratamento além de partilhas de aço LN28 cementadas, como contracorpo foi utilizado uma esfera de aço AISI 52100 adquiridas comercialmente. Três tipos de óleos lubrificantes foram utilizados: óleo mineral, óleo de mamona e óleo de soja epoxidado. Com intuito de analisar os resultados obtidos nestes ensaios, foi calculado o volume desgastado de material nas amostras, e após a realização destes ensaios foi analisada a superfície dos corpos de prova em microscópio óptico, MEV e AFM. Foi medida também a molhabilidade dos lubrificantes nas superfícies estudadas. Os materiais submetidos a tratamento termoquímico apresentaram um melhor desempenho tribológico na maioria dos testes. Assim também, o óleo mineral, que apesar de possuir uma viscosidade inferior aos óleos vegetais utilizados, apresentou um melhor desempenho devido as propriedades inerentes a este tipo de lubrificante. / Thermochemical processes are used in the industry to improve the surface properties of the components of mechanical systems. In such systems lubrication are very important as well. Most common lubricants are mineral oil based but there are several studies analyzing performance of lubricants formulated from vegetable oils. However there are few studies about the interaction between surface and biofluids. It is important to know the behavior of the modified surface by thermochemical treatments interacting with different lubricants. In order to address this subject this study proposed to compare tribological behavior of surfaces modified by thermochemically and not modified when different lubricants are acting in the surface. Lubricants used were vegetable based (castor oil and epoxidized soybean oil) and mineral based (paraffinic oil). Tribological studies were performed by ball cratering test using samples from SAE 4140 submitted to nitriding and nitrocarburizing against AISI 52100 spheres. It was also tested samples from carburized LN 28 steel. Worn volume were calculated and characterization of the crater after test were made using SEM and AFM. Wetting was also measured for the different surface condition and lubricants. Results showed better performance of the modified surfaces using mineral oil as lubricant despite their lower viscosities.

Atherogenesis is the leading cause of death in the developed world, and is putting considerable monetary pressure on health systems the world over. Although the risk factors are well understood, unfortunately, the initiation and development of this disease still remains relatively poorly understood, but it is becoming increasingly identifiable as a dysfunction of the endothelial cells that line the walls of arteries. The prevailing haemodynamic environment plays an important role in the focal nature of atherosclerosis to very specific regions of the human vasculature. Disturbed haemodynamics lead to very low wall shear stress, and inhibit the transport of important blood borne chemicals. The present study models, both computationally and mathematically, the transport and hydrolysis of important blood borne adneosine nucleotides in physiologically relevant arterial geometries. In depth analysis into the factors that affect the transport of these low diffusion coefficient species is undertaken. A mathematical model of the complex underlying endothelial cell dynamics is utilised to model production of key intracellular molecules that have been implicated into the complex initiation processes of atherosclerosis; hence regions of the vasculature can be identified as being 'hot spots' for atherogenesis. This model is linked into CFD software allowing for the assessment of how 3D low yields and mass transfer affect the underlying cell signalling. Three studies are undertaken to further understand nucleotide variations at the endothelium and to understand factors involved in determining the underlying cell dynamics. The major focus of the first two studies is geometric variations. This is primarily due to the plethora of evidence implicating the geometry of the human vasculature, hence the haemodynamics, as an influential factor in atherosclerosis initiation. The final model looks at a physiologically realistic geometry to provide a more realistic reproduction of the in vivo environment.

Tratamentos termoquímicos são processos utilizados pela indústria em componentes de sistemas mecânicos com o intuito de melhorar as suas propriedades superficiais, em especial o desempenho em desgaste. Esses sistemas são utilizados em conjunto com lubrificantes em máquinas e equipamentos dos mais variados tipos. Normalmente os lubrificantes mais usados em função do seu bom desempenho, são de base mineral. Entretanto, há vários estudos propondo o uso de lubrificantes de base vegetal mas pouco se conhece da interação da superfície com esses biofluidos. Sendo assim é importante se identificar como uma superfície tratada ou não, irá interagir com os diferentes tipos de lubrificantes. Dentro deste escopo, este trabalho se propõe a comparar a resposta tribológica de superfícies tratadas termoquimicamente ou não quando lubrificada com biofluidos e com óleos derivados de petróleo. O estudo foi realizado por meio do método \"ball-cratering test\". Como corpos de prova, foram utilizados pastilhas de aço AISI 4140 submetidas aos tratamentos termoquímicos de nitretação e nitrocementação e também sem tratamento além de partilhas de aço LN28 cementadas, como contracorpo foi utilizado uma esfera de aço AISI 52100 adquiridas comercialmente. Três tipos de óleos lubrificantes foram utilizados: óleo mineral, óleo de mamona e óleo de soja epoxidado. Com intuito de analisar os resultados obtidos nestes ensaios, foi calculado o volume desgastado de material nas amostras, e após a realização destes ensaios foi analisada a superfície dos corpos de prova em microscópio óptico, MEV e AFM. Foi medida também a molhabilidade dos lubrificantes nas superfícies estudadas. Os materiais submetidos a tratamento termoquímico apresentaram um melhor desempenho tribológico na maioria dos testes. Assim também, o óleo mineral, que apesar de possuir uma viscosidade inferior aos óleos vegetais utilizados, apresentou um melhor desempenho devido as propriedades inerentes a este tipo de lubrificante. / Thermochemical processes are used in the industry to improve the surface properties of the components of mechanical systems. In such systems lubrication are very important as well. Most common lubricants are mineral oil based but there are several studies analyzing performance of lubricants formulated from vegetable oils. However there are few studies about the interaction between surface and biofluids. It is important to know the behavior of the modified surface by thermochemical treatments interacting with different lubricants. In order to address this subject this study proposed to compare tribological behavior of surfaces modified by thermochemically and not modified when different lubricants are acting in the surface. Lubricants used were vegetable based (castor oil and epoxidized soybean oil) and mineral based (paraffinic oil). Tribological studies were performed by ball cratering test using samples from SAE 4140 submitted to nitriding and nitrocarburizing against AISI 52100 spheres. It was also tested samples from carburized LN 28 steel. Worn volume were calculated and characterization of the crater after test were made using SEM and AFM. Wetting was also measured for the different surface condition and lubricants. Results showed better performance of the modified surfaces using mineral oil as lubricant despite their lower viscosities.

On vessel wall injury the complex process of blood coagulation is set off. It is composed of vasoconstriction, primary hemostasis, secondary hemostasis and fibrinolysis. This work enriches current model of primary hemostasis of Storti. The previous model used ALE formalism for tracing of development of platelet plug. The phase field method is used for tracing of the development of interface blood-thrombus. Storti's primary hemostasis was extended to capture the fact, that the platelets can be activated in the blood flow in the area of reactive surface not only by influence of chemical agents like thromboxane, ADP and thrombin but also by their exposure to elevated values of shear stress. In our first approach we deal the emerging thrombus as a fluid with very high viscosity. In the second approach it was assumed, that platelet plug develops as a viscoelastic material according to constitutive equations of clot introduced by Kempen. In this manner platelet clot matures into blood clot. In both approaches the blood is represented as a non-Newtonian fluid. The framework of the phase field method was applied also to the model of high shear rate thrombosis of Weller. Weller's original model of Weller took advantage of the cylindrical symmetry of computational domains for its computations, hence the...

A mathematical model of blood flow in infants with hypoplastic left heart syndrome (HLHS) was improved by adding cerebral autoregulation. This is the process by which blood vessels constrict or dilate to keep blood flow steady in certain organs during pressure changes. The original lumped parameter model transformed the fluid flow into an electrical circuit. Its behavior is described using a system of thirty-three coupled differential equations that are solved numerically using a fourth-order Runge-Kutta method implemented in MATLAB. A literature review that includes a discussion of autoregulation mechanisms and approaches to modeling them is followed by a description of the model created for this paper. The model is based on the baroreceptor or neurogenic theory of autoregulation. According to this theory, nerves in certain places within the cardiovascular system detect changes in blood pressure. The brain then compensates by sending a signal to blood vessels to constrict or dilate. The model of the control system responded fairly well to a pressure drop with a steady state error of about two percent. Running the model with or without the control system activated had little effect on other parameters, notably cardiac output. A more complete model of blood flow control would include autonomic regulation. This would vary more parameters than local autoregulation, including heart rate and contractility. This is suggested as a topic of further research.

This thesis deals with the mechanics of the Intra-Aortic Balloon Pump (IABP), the most widely used temporary cardiac assist device, whose beneficial action is based on the principle of counterpulsation. The investigation is carried out in vitro in increasingly more realistic setups, including a mock circulatory system with physiological distribution of peripheral resistance and compliance in which IABP counterpulsation was simulated. Pressure and flow measurements show the effect of variables such as intra-luminal pressure, angle and aortic compliance on balloon hemodynamics. These data are complemented by results on the duration of balloon inflation and deflation obtained by means of high-speed camera visualisation. Furthermore, wave intensity analysis is carried out and it is identified as a possible alternative method for the assessment of IABP performance. This work includes two prototypes of intra-aortic balloons of novel shape with the balloon chamber tapering both from and toward the balloon tip. In clinical terms, with reference to the semi-recumbent position in which patients assisted with the IABP are nursed in the intensive care unit, the results presented in this thesis indicate that operating the balloon at an angle compromises the benefit of counterpulsation when assessed in vitro.

Microfluidics deals with the behavior, control and manipulation of fluids which are confined at micrometer length scale. It has important application in lab-on-a chip technology, micro-propulsion, additive manufacturing, and micro-thermal technologies. Microfluidics has been widely used in detection, separation, transportation, and mixing of fluids and particles. The work carried out for the thesis to study the fluid-structure interaction in micro-channel involves an experimental part and a simulation part. In the experimental part the characterization of biofluid (RBC in BSA) is carried out based on the power law of fluid and flow behavior is studied. Also the dependence of fluid concentration on the viscosity in the channel is studied. The results are analyzed. Transition of fluid behavior from non-Newtonian shear thickening to non-Newtonian shear thinning is observed when the RBC concentration varies from 5.5×106 to 5.5×107 cells/ml in the channel. From the viscosity measurements of the biofluid it is observed that the average viscosity in the channel increases on increasing concentration of the fluid for shear thickening fluids. In the simulation part, interaction behavior of biomolecule DNA is studied in the channel containing biofluid which is characterized in the experimental part. Cell free DNAs are common problem in infectious disease detection. Based on the assumptions of the WLC model, DNA strand is assumed as a one dimensional elastic member with its one end fixed at the channel wall and the other end free to move in the fluid. Bent and straight DNAs are considered for the study. Multiple scales are involved in this problem which is not fully understood. DNA strands in the channel are exposed to different forces in the channel which are mainly due to the pressure and viscous effects. Numerical simulations are carried out for the multiphysics problem of DNA in the fluid using a coupled multiphysics finite element scheme and the results are obtained. Same procedure is carried out considering smaller channels and also for PBS solution as background fluid to obtain consistent results. It is found that when the channel width increases the tip displacement of DNA decreases. It was observed that DNA tip displacement is more in the channel when its end-to-end length is approximately half the width of the channel. Potential application of these modeling and simulation are in molecular screening processes to improve the performance of microfluidic DNA chips, and in design of micro-channel structures of microfluidic devices.

No description available.