Reações de oxidação lipídica são responsáveis pelo desenvolvimento de sabores e odores desagradáveis tornando os alimentos impróprios para consumo, sendo necessário o uso de antioxidantes. O ácido ascórbico (AA) é um antioxidante muito eficaz, que exibe função vitamínica, no entanto é relativamente instável. Com o objetivo de aumentar a estabilidade do AA e, consequentemente, facilitar sua aplicação em produtos alimentícios, os métodos de encapsulação por coacervação complexa e por dispositivos microfluídicos foram testados. Primeiramente foi apresentada a Revisão Bibliográfica no Capítulo 1, e em seguida, a encapsulação por coacervação complexa, como será visto no Capítulo 2. Neste caso, nove tratamentos foram obtidos utilizando-se gelatina e goma arábica como materiais de parede e analisados com relação à morfologia, por microscopia ótica e eletrônica de varredura, umidade, atividade de água, higroscopicidade, solubilidade, potencial zeta, espectroscopia no infravermelho por transformada de Fourier (Ftir), tamanho e distribuição de tamanho de partículas, cor instrumental, eficiência de encapsulação e estabilidade do material encapsulado. No capítulo 3 serão apresentados resultados obtidos na encapsulação do AA pelo método de dispositivos microfluídicos. Cinco tratamentos foram obtidos, sendo analisados com relação à morfologia, por microscopia ótica, eletrônica de varredura e confocal, eficiência de encapsulação, tamanho e distribuição de tamanho de partícula e estabilidade do material encapsulado. A obtenção das microcápsulas de AA pelos dois métodos citados foi viável uma vez que apresentaram altos valores de eficiência de encapsulação e ótima atuação em relação à proteção do AA durante estocagem. Comparando-se os dois métodos, as cápsulas obtidas por dispositivos microfluídicos conferiram melhor estabilidade ao ácido ascórbico, no entanto amostras obtidas por coacervação complexa foram aplicadas em salsicha devido a maior quantidade de AA presente em sua constituição. O efeito da aplicação das microcápsulas nas salsichas foi avaliado durante 40 dias de armazenamento refrigerado como será visto no Capítulo 4. Cinco tratamentos foram elaborados e analisados de acordo com a estabilidade da emulsão cárnea durante o processamento, umidade, atividade de água, alteração do pH, determinação da cor instrumental, perfil de textura instrumental, estabilidade oxidativa pelo método de substâncias reativas ao ácido tiobarbitúrico (TBARS) e aceitação sensorial. A aplicação das microcápsulas de AA em salsicha foi possível sem comprometer a qualidade do produto final. Todos os dados obtidos foram analisados estatisticamente por análise de variância ANOVA e teste de Tukey, ao nível de 5% de significância com auxílio do programa SAS. Os experimentos relacionados à encapsulação por coacervação complexa e aplicação das microcápsulas em salsicha foram realizados no Laboratório de Produtos Funcionais, nas dependências do Departamento de Engenharia de Alimentos da FZEA/USP. Os experimentos relacionados à utilização de dispositivos microfluídicos foram realizados nos laboratórios do professor David A. Weitz, da Escola de Engenharia e Ciências Aplicadas de Harvard, da Universidade de Harvard, Cambridge, Estados Unidos. / Lipid oxidation reactions are responsible for the development of unpleasant tastes and odors making food unfit for consumption. For this reason, the use of antioxidant is necessary. Ascorbic acid (AA) is a very effective antioxidant with vitamin function, however it is relatively unstable. With the aim of increasing the stability of AA and thus improve its application in food products, the methods of encapsulation by complex coacervation and microfluidic devices were tested. First of all the Literature Review is presented in Chapter 1. The encapsulation by complex coacervation can be seen in Chapter 2. For this methodology, nine treatments were obtained using gelatin and gum Arabic as encapsulant agent and analyzed regarding to morphology by optical and scanning electron microscopy, moisture, water activity, hygroscopicity, solubility, Zeta Potential, Fourier transform infrared Spectroscopy (FTIR), particle size and particle size distribution, instrumental color, encapsulation efficiency and stability of the encapsulated material. The results obtained for AA encapsulation by microfluidic device will be presented in Chapter 3. Five treatments were obtained and analyzed regarding to morphology by optical, scanning electron and confocal microscopy, encapsulation efficiency, particle size and particle size distribution and stability of the encapsulated material. The production of AA microcapsules by the two methods mentioned was feasible once that showed high levels of encapsulation efficiency and optimal performance regarding to the protection of AA during storage. Comparing the two methods, the microcapsules obtained by microfluidic device conferred better stability to AA, however samples obtained by complex coacervation were applied in sausage due to the greater amount of AA in its constitution. The effect of the application of microcapsules in sausages was evaluated during 40 days at refrigerated storage as it will be seen in Chapter 4. Five treatments were prepared and analyzed according to the stability of the meat emulsion during processing, moisture, water activity, pH changes, determination of instrumental color, instrumental texture profile, oxidative stability by the method of thiobarbituric acid reactive substances (TBARS) and sensory acceptance. The application of AA microcapsules in sausage was possible without compromising the quality of the final product. All data were statistically analyzed by ANOVA and Tukey test, at 5% of significance with the use of SAS software. The experiments related to encapsulation by complex coacervation and application of microcapsules in sausage were carried out at Laboratory of Functional Products, at Department of Food Engineering, FZEA / USP. The experiments related to the use of microfluidic devices were performed in the laboratories of Professor David A. Weitz, at School of Engineering and Applied Sciences of Harvard, at Harvard University, Cambridge, USA.

Recentemente estudos demonstraram que os SNPs (polimorfismos de base única) rs8099917 e rs12979860 localizados próximos ao gene da IL28B explicam a variação de resposta à infecção e tratamento do paciente contra o genótipo 1 do HCV, porém não para o genótipo 3 deste vírus. Este trabalho encontrou associação significativa entre resposta à infecção devida ao genótipo 3 pelo tratamento (PEG-INF e RBV) e o polimorfismo rs8099917 em uma amostra da população de Santos - SP. Para o polimorfismo rs12979860, esta associação somente foi encontrada ao se parear indivíduos para sexo, idade e grau de fibrose hepática, demonstrando a importância da retirada de efeitos de estratificação neste tipo de análise. Estes resultados se confirmam ao se agregar dados de uma população proveniente da Bahia em uma meta-análise. Além disso, fez-se um estudo GWAS a fim de se conhecer outras variações genéticas envolvidas nessa resposta. Esta análise indicou a existência de alguns SNPs candidatos com sugestão de associação, dentre eles a tiroglobulina, relacionada aos hormônios da tireóide. / Recently, studies have shown that SNPs (single nucleotide polymorphisms) rs8099917 and rs12979860, located near the gene IL28B explain the changes in the response to infection and treatment of a patient against the HCV genotype 1, but not for the genotype 3 of the virus. This study found a significant association between response to infection due to treatment by genotype 3 (PEG-INF and RBV) and the rs8099917 polymorphism in a population sample from Santos - SP. To the rs12979860 polymorphism, this association was only found when individuals are paired for sex, age and degree of hepatic fibrosis, demonstrating the importance of the withdrawal effects of stratification in this type of analysis. These results confirm the aggregate data from a population of Bahia in a meta-analysis. In addition, a GWAS was made in order to search other genetic variations involved in this response. This analysis indicated the existence of some candidate SNPs with suggestion of association, including thyroglobulin, thyroid hormones related to.

Le radiomarquage de molécules d’intérêt avec des isotopes radioactifs est d'un grand intérêt pour la communauté scientifique, car il influe fortement sur le processus de découverte dans les sciences de la vie et en médecine nucléaire. Les molécules radiomarquées ont été largement utilisées pour évaluer les réactions biochimiques, pour mesurer la distribution in vivo d'une substance ou pour réaliser des tests RIA (RadioImmunoAssay). En médecine nucléaire, des radiopharmaceutiques pour la thérapie par ra-dio-isotopes (RIT) et des radiotraceurs pour des expériences d'imagerie telles que la TEP (tomographie par émission de positons), la tomographie par émission monophotonique (TEMP) ou la scintigraphie ont été décrites. Plusieurs isotopes de l'iode peuvent être utilisés à la fois pour le diagnostic et le traite-ment : 123I pour l'imagerie TEMP, 124I pour la TEP, 125I pour l'analyse biologique et 131I pour la radio-thérapie et la scintigraphie.Les méthodes classiques de radio-iodation reposent sur l'utilisation d'un précurseur pré-fonctionna-lisé, qui doit être synthétisé, isolé et purifié avant d'être introduit à l'étape de radio-iodation. La méthode par radioiododéstannylation est la méthode la plus populaire, bien que les précurseurs stannylés soient connus pour leur synthèse difficile et leur toxicité. Le développement de nouvelles méthodes de radio-iodation représente donc un grand intérêt dans le domaine de la radiochimie.Sur la base de travaux antérieurs, notre groupe a mis au point une méthode de radio-iodation de N-acylsulfonamides au moyen d’une radio-iodation C-H médiée par le palladium à température ambiante. Cette stratégie originale permet le radiomarquage de molécules d’intérêt dans des conditions très douces sans utiliser de précurseurs chimiques.Sur la base de la littérature, notre groupe développe actuellement une nouvelle méthode de radio-iodation de dérivés d’arylsilanes par radioiododésilylation dans des conditions douces. Cette méthodo-logie générale permet pour le moment le radiomarquage de dérivés d'arylsilanes activés en conditions douces. / Labeling of (bio)molecules with radioactive isotopes is of high interest to for the scientific commu-nity, as it strongly impacts the discovery process in life science and nuclear medicine. Radiolabeled molecules have been extensively used to assess biochemical reactions, to measure in vivo distribution of a substance or to preform RIA (RadioImmunoAssay). In nuclear medicine, radio-therapeutics for RIT (RadioIsotope Therapy) and radio-tracers for molecular imaging experiments such as PET (Positron Emission Tomography), SPECT (Single Photon Emission Computed Tomography) or scintigraphy have been described. Several useful isotopes of iodine can be used for both diagnosis and therapy: 123I for SPECT imaging, 124I for PET imaging, 125I for biological assays and 131I for radio-therapy and scintig-raphy.Classical methods of radioiodination methods use a prefunctionalized precursor, which must be syn-thesized, isolated and purified before being introduced to the radio-iodination step. The radioiodode-stannylation method is the most popular method, although stannylated precursors are known for their difficult synthesis and their toxicity. The development of new methods of radioiodination is therefore of great interest in the field of radiochemistry.Based on a previous work, our group has developed a method to radio-iodinate N-acylsulfonamides through a room temperature palladium mediated C-H radio-iodination. This original strategy allows radiolabeling of biomolecules in very mild conditions without the use of chemical precursors.Based on literature, our group is now developping a new method to radio-iodinate arylsilyl derivates through radioiododesilylation in mild conditions. This general methodology allows for the moment the radiolabeling of activated arylsilyl derivates in mild conditions.

This work is aimed to design and implement software for simulating operational properties of heat pumps and process data from measurements. Work contains the issue of heat pumps, their principle of functionality, different types of systems and coefficients used for rating of efficiency of heat pumps. Next it contains physical or electrical parameters that needs to be measured by designed system. The result is functional software, which contains mathematical library written in C++ and graphical user interface written in C#.

In this dissertation we develop aspects of ergodic theory for C*-dynamical systems for which the C*-algebras are allowed to be noncommutative. We define four ergodic properties, with analogues in classic ergodic theory, and study C*-dynamical systems possessing these properties. Our analysis will show that, as in the classical case, only certain combinations of these properties are permissable on C*-dynamical systems. In the second half of this work, we construct concrete noncommutative C*-dynamical systems having various permissable combinations of the ergodic properties. This shows that, as in classical ergodic theory, these ergodic properties continue to be meaningful in the noncommutative case, and can be useful to classify and analyse C*-dynamical systems. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Mathematics and Applied Mathematics / unrestricted

Orientador: Rejane Maria Tommasini Grotto / Resumo: A progressão da fibrose hepática somada à infecção pelo vírus da hepatite C (VHC) tem sido associada à resposta imunológica permanente. O estudo no repertório de anticorpos Anti-VHC na progressão da fibrose hepática foi explorado através de ferramentas de sequenciamento em larga escala (NGS) possibilitando uma análise de repertórios altamente variáveis como as porções variáveis VH (cadeia pesada) e Vk (cadeia leve) das imunoglobulinas, e a determinação de famílias e subfamílias dos genes V-D-J associadas à resposta humoral encontrada nas diferentes fases da doença proporcionam uma ferramenta importante no entendimento da resposta imune frente à infecção viral pelo VHC. As porções VH e Vk das imunoglobulinas foram obtidas a partir da amplificação de RNA de sangue de paciente VHC positivos e com diferentes graus de fibrose, e sequenciadas na plataforma Illumina® Miseq, fornecendo uma grande variabilidade de sequências que foram pré-processadas por ferramentas de bioinformática e analisadas em dois bancos de anticorpos diferentes: IgBlast (NCBI) e IMGT® quanto às famílias e subfamílias mais expressas. A expressão restrita de algumas famílias e subfamílias: IGHV1, IGHV3, IGHV4 e subfamílias já descritas em vários estudos associados ao VHC corrobora com nossos achados de que existe uma tendência do uso de algumas subfamílias como: IGHV1-2, IGHV1-8, IGVH1-69, IGHV3-11, IGHV3-21, IGHV3-23, IGVH3-30, IGHV4-4, IGHV4-34 IGHV4-39 na cadeia pesada; assim como IGkV3-15 e IGkV3-20 na cadei... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The progression of hepatic fibrosis in the hepatitis C virus (HCV) infection has been linked with permanent immune response. The study in the repertoire of Anti-HCV antibodies in the progression of hepatic fibrosis was analysed for large-scale sequencing (NGS) tools enabling a highly variable analysis such as the VH (heavy chain) and Vk (light chain) portions of immunoglobulins and the determination of families and subfamilies of the V-D-J genes in the humoral response found in the different phases of the disease, a great tool in the understanding of the immune response to HCV viral infection. The VH and V portions of the immunoglobulins were obtained from the amplification of HCV positive HCV patient blood with different degrees of fibrosis and sequenced on the Illumina® Miseq platform, providing a large sequence variability that was preprocessed by tools of bioinformatics and analyzed in two different antibody banks: IgBlast (NCBI) and IMGT® for the most expressed families and subfamilies. The restricted expression of some families: IGHV1, IGHV3, IGHV4 and subfamilies already described in several HCV-related studies confirm our findings that there is a tendency to use some subfamilies, such as: IGHV1-2, IGHV1-8, IGVH1- 69, IGHV3-11, IGHV3-21, IGHV3-23, IGVH3-30, IGHV4-4, IGHV4-34 IGHV4-39 in the heavy chain; as well as IGkV3-15 and IGkV3-20 in the light chain, but the subfamilies: IGHV1-8, IGHV3-11, IGHV4-39, IGkV1-5, IGkV1-12, IGkV1-39 were also among the most expressed, i... (Complete abstract click electronic access below) / Mestre

Objetivos: La presente tesis tuvo como objetivo general caracterizar nutricionalmente un néctar elaborado a partir de lactosuero dulce, y Myrciaria dubai (camu - camu) edulcorado con Sstevia rebaudiana (stevia). Materiales y métodos: Fue un estudio experimental de laboratorio, donde se evaluó el efecto de las dosis de lactosuero (30%, 50% y 70%) y pulpa de camu camu (70%, 50% y 30%) sobre sus propiedades nutricionales y sensoriales. Resultados: Los análisis físicoquímicos de las tres formulaciones cumplieron con los estándares de calidad para bebidas de frutas. La evaluación sensorial se realizó a 79 panelistas no entrenados, los cuales determinaron que la formulación que contenía 70% pulpa de camu - camu y 30% lactosuero fue la que presentó el mayor puntaje en la evaluación sensorial siendo solo de 2,5/7 en una escala hedónica, por lo que se recomienda mejorar las formulaciones. Discusión: El análisis físico químico de las bebidas formuladas mostró que el néctar a base de lactosuero con camu camu presentó en 100 gramos de producto un bajo nivel de calorías un promedio de 23 Kcal/ 100g, 5,3% de carbohidratos, 0,4% de proteína, 0,1% de grasa, 93,8% de agua, 0,4% de cenizas. El análisis microbiológico indicó que cumplen con la Norma sanitaria que establece los criterios microbiológicos de calidad para néctares, lo que garantiza la inocuidad del producto. Se realizó el análisis de vitamina C en la pulpa de camu-camu, la mezcla de la bebida antes de la pasteurización y luego de la pasteurización siendo estos: 195,8mg/100g, 180,7 mg/100g, 168,3mg/100g respectivamente observándose que en el producto final existe una disminución de alrededor del 14,04% con respecto al contenido inicial en el camu-camu. Conclusión: Las características nutricionales del néctar elaborado a partir de lactosuero, camu camu edulcorado con Stevia presentó un leve incremento en el valor de proteínas (0,3g/100ml) que los néctares comerciales (0g/100ml) que se expenden en el país, pero destaca por su contenido alto de vitamina C (168,3mg/100ml), sin embargo, la incorporación del lactosuero no resultó en una clara aceptabilidad sensorial en jóvenes por ende se rechaza la hipótesis que el lactosuero aumenta la aceptabilidad sensorial. Asimismo, se acepta la hipótesis que aumenta la calidad nutricional del néctar en comparación con bebidas similares que se expenden en el mercado nacional. / Objective: The aim of this thesis was to characterizing nutritionally a nectar elaborated from whey and Myrciaria dubai (camu - camu) sweetened with Stevia rebaudiana (stevia).Materials and Methods: It was an experimental laboratory study, where was evaluated the effect of the dose of whey (30%, 50% and 70%) and camu camu pulp (70%, 50% and 30%) on its sensory and nutritional properties. Results: The physical-chemical results of the three formulations got the quality standards for fruit beverage. The sensory evaluation was performed with 79 untrained panelists, who determined that the formulation contained 70% of camu-camu pulp and 30% of of whey it was the one that presented the highest score in the sensory evaluation being only 2.5 / 7 on a hedonic scale, so it is recommended to improve the formulations. Discussion: The physical chemical analysis of the formulated beverages showed that the whey-based nectar with camu camu showed a low calorie level in 100 grams of product, an average of 23 Kcal / 100g, 5.3% carbohydrates, 0.4% of protein, 0.1% fat, 93.8% water, 0.4% ash. The microbiological analysis indicated that they satisfy the sanitary norm that establishes the microbiological criteria of quality for nectars, which guarantees the safety of the product. We realized the analysis of vitamin C in the camu-camu pulp, in the mixture of the beverage, before the pasteurization and after the pasteurization, being these: 195,8mg / 100g, 180,7 mg / 100g, 168,3mg / 100g respectively, evidencing that in the final product there is a decrease of about 14,04% with respect to the initial content of camu -camu. Conclusion: The nutritional characteristics of the nectar made from whey, camu camu sweetened with Stevia presented a slight increase in the value of proteins (0.3g / 100ml) than commercial nectars (0g / 100ml) that are sold in the country, but it stands out Due to its high content of vitamin C (168.3mg / 100ml), however, the incorporation of whey did not result in a clear sensory acceptability in young people, therefore the hypothesis that whey increases sensory acceptability is rejected. Likewise, the hypothesis that increases the nutritional quality of nectar in comparison with similar beverages that are sold in the national market is accepted. / Tesis

Le cancer spinocellulaire (CSC) est le cancer de la peau le plus fréquent chez l’homme. Son étiologie est liée à l'exposition aux rayonnements ultraviolets (UV). Le xeroderma pigmentosum C (XP-C) est une maladie génétique caractérisée par l’absence de la protéine XPC entrainant une déficience dans la réparation des lésions dans l’ADN induites par les UV. La persistance de ces lésions chez ces patients entraine l’apparition précoce de CSC particulièrement agressifs. Les fibroblastes cutanés XP-C présentent un phénotype ressemblant à celui des fibroblastes associés aux cellules cancéreuses, suggérant un rôle promoteur dans le développement précoce des CSC XP-C. Nous avons étudié les effets des fibroblastes XP-C sur l’invasion de cellules de carcinomes. Dans des cultures organotypiques de peau, les fibroblastes XP-C favorisent l'invasion des cellules de CSC. De plus, ex vivo, la cicatrisation des cellules CSC est plus rapide en présence de surnageants de culture de fibroblastes XP-C et est due à un effet mitogénique des fibroblastes XP-C qui augmente la proportion des cellules de CSC dans la phase G2-M du cycle. Les fibroblastes XP-C surexpriment le facteur de croissance HGF qui active le récepteur c-Met et les voies de signalisation p38 et JNK dans les cellules de CSC. Le blocage de HGF entraîne l’inactivation de c-Met, p38 et JNK et bloque l'invasion des cellules CSC. De plus, nous montrons que les fibroblastes XP-C jouent un rôle de cellules « leader » dans l’invasion des CSC. Les fibroblastes XP-C créent un microenvironnement permissif à l'invasion des CSC. Des thérapies ciblant les fibroblastes XP-C pourraient permettre le contrôle de l’invasion des CSC chez les XP. / Squamous cell carcinoma (SCC) is the most frequent metastatic skin cancer. His etiology is linked to exposure to ultraviolet radiation (UVR). Xeroderma pigmentosum C (XP-C) is a genetic disorder characterized by a severe susceptibility to aggressive SCCs following minimal exposure to UVR. XP-C cells are deficient in nucleotide excision repair (NER) of UV-induced DNA lesions. XP-C dermal fibroblasts expresse a phenotype resembling that of stromal fibroblasts associated to cancer cells with accumulation of reactive oxygen species and over expression of matrix metalloproteinase 1 (MMP1). We explored the effects of XP-C fibroblasts on migration and invasion of SCC cells. In organotypic skin cultures, XP-C fibroblasts promote the invasion of SCC cells. Also, scratch healing of SCC cells is enhanced with culture supernatants of XP-C fibroblasts through a mitogenic effect connected to increased ratio of SCC cells in the G2-M phase of the cell cycle. We show that XP-C fibroblasts overexpress the hepatocyte growth factor/scatter factor (HGF/SF) and activate the c-Met receptor and the p38 and JNK pathways in SCC cells. Blockage of HGF inhibits c-Met, p38 and JNK activation and prevented invasiveness of SCC cells within dermal equivalents. Spheroid assays show that XP-C fibroblasts lead SCC invasions. Our data indicate for the first time that XP-C fibroblasts are responsible for the formation of a permissive microenvironment towards SCC cells proliferation and invasion. Therapies targeting XP-C fibroblasts may be considered as a way to control aggressive cancer in XP-C patients.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biological and Medical Sciences Student: Monika Dobrovodová Supervisor of master thesis: PharmDr. Miroslav Kovařík, Ph.D. Advisor of master thesis: prof. MUDr. Karel Martiník, DrSc. Title of master thesis: Relation among BMI, hyperinsulinemia and selected biochemical indicators This thesis is focussed on specification of relations among BMI, insulinemia, age of the patients, C-peptid blood levels and glycemia and also searching relations among selected parameters of lipid spectrum in group of selected patients. Measuring of body height and weight and investigation of fasting glycemia, insulinemia, total cholesterolemia, blood levels of HDL and LDL and also C-peptid were done at 3472 patients. Afterwards few basic indexes of insulin resistance and sensitivity were counted. In this group was proven, that fasting insulinemia and C-peptid levels are increasing in according to increasing BMI. Also fasting glycemia is increasing modestly. Insulin resistance and sensitivity indexes used in this theses depends on BMI. Although statistically significant differences between age groups were proven according to insulin resistance and sensitivity indexes, we can't see clearly increasing or decreasing tendency in according to...

AN ABSTRACT OF THE THESIS OFChristoph Michael Goettler, for the Master of Science degree in Mechanical Engineering, presented on Nov 6, 2020, at Southern Illinois University Carbondale. TITLE: EFFECT OF DENSITY ON FRICTION AND WEAR PERFORMANCE OF CARBON-CARBON COMPOSITE MATERIALSMAJOR PROFESSOR: Dr. Peter FilipCarbon-carbon (C/C) composite materials exhibit high thermal conductivity, high thermal stability, low density, and high mechanical strength. Due to these properties, C/C composites are ideal for use in high performance braking systems. However, C/C composites are incredibly expensive to manufacture, and thus improving the longevity of these materials is vital. C/C composite materials inherently have a density gradient due to manufacturing limitations. By determining the effect of density on friction and wear performance of C/C composite materials, manufacturers could use that data to alter manufacturing methods to improve the lifespan of C/C composites. In this study, the effect of density on friction and wear performance of C/C composite materials was studied. Friction tests were conducted through use of a universal mechanical tester (UMT) manufactured by Bruker and subsequent analysis was done through use of scanning electron microscopy, energy dispersive x-ray spectroscopy, and polarized light microscopy. Numerous samples from depths of 0 mm and 5 mm were taken from two C/C composite materials with varying matrices and friction tested at varying conditions to determine friction properties, friction surface characteristics, microstructure just below the friction surface characteristics, friction layer characteristics, and wear characteristics. Density, apparent density, and apparent porosity gradients were also measured to be able to correlate observations to density differences. It was observed that while density does not seem to be the main cause in differences in friction and wear performance of C/C materials at depths of 0 mm and 5 mm, there still existed significant differences in friction performance, wear performance, and post friction test material characteristics when comparing 0 mm samples to 5 mm samples. In conclusion, density was not found to be a significant cause in variations in friction performance. However, friction surface depth was found to have a significant effect on friction performance, wear performance, and the friction surface. Further research is needed to be able to determine the exact cause of the variations in performance at depths of 0 mm and 5 mm. Keywords: carbon-carbon, composite, C/C, density, friction, wear, brake