Ultra-high performance concrete (UHPC) has progressively gained interest because of its favorable strength and durability properties. Literature shows that curing temperature has a significant effect on the resultant mechanical properties of UHPC, generally resulting in increased compressive strength. However, limited datasets are currently available to ascertain the degree of change related to compressive strength as a function of curing temperature and conditions. This study investigates the effect of isothermal and submerged curing temperature conditions, ranging from 10°C to 90°C, on the compressive strength and elastic modulus development of UHPC and generates a numerical model to capture these effects. The extent and rate of compressive strength development in Cor-Tuf UHPC was found to increase with curing temperature, while only the rate of elastic modulus development increased with curing temperature. The numerical model shows reasonable agreement when compared with the experimental results and was successfully implemented in finite element analysis software.

Genom att generera mer information om hälsenan i form av dess elasticitet kan förhoppningsvis fler slutsater nås gällande diagnostik och behandling. Elastografi med hjälp av ultraljud skulle kunna vara en metod för att bidra med denna information. För att utföra detta anpassades en mjukvara utifrån ett grundläggande basprogram för elastografimätningar, utvecklat av företaget Verasonics, för att kunna utföra elastografi av hälsenan genom programmering i matlab. Tidigare undersökningsmetoder för elastografi är utvecklade för större organ, varför anpassningen innebar att använda metoder som även ger tillförlitlig information för mindre organ. För att göra detta anpassades först mjukvaran för en mindre fantom med liknande djup som hälsenan. När det konstaterats att skjuvningsvågor genererats på rätt avstånd kunde sedan mätningar göras på hälsenan. Genom att bestämma hastigheten av de genererade skjuvningsvågorna kunde sedan skjuvmodulen, följt av elasticitetsmodulen, beräknas för vävnaden. Denna bestämdes först genom grupphastigheten av skjuvningsvågorna, vilket är den metod som används vid större organ, följt av fashastigheten av skjuvningsvågorna vilket tar hänsyn till vågens dispersion. Detta gav då hälsenans elasticitetsmodul enligt grupphastighet samt fashastighet som sedan kunde jämföras. Slutligen gick det att konstatera att elasticitetsmodulen kommer att variera beroende på vilken typ av hastighet denna härleds från. Detta indikerar då på att sjuvningsvågen interagerar med organets gränsyta vilket orsakar dispersion. / Generating more information about the achilles tendon, such as its elasticity, will hopefully lead to more conclusions and results within both diagnostics as well as treatment. Elastography by ultrasound could be a method to contribute with this information. To do so, a basic software,provided and developed by the company Verasonics for elastography was specialized to fit the achilles tendon by programing in matlab. Earlier methods to perform elastography are developed for larger organs, hence the adjustment will include methods that acquire trustworthy information from smaller organs. To do so the adjustment of the software was first made to work on a smaller phantom with similar symmetry as the achilles tendon. When it was confirmed that shear waves were generated at the correct distance this enabled further measurements on the achilles tendon. By deciding the speed of the generated shear waves the shear modulus, followed by the elastic modulus, could then be estimated for the tissue. This was first decided by the group velocity of the shear waves, as the usual method done on larger organs, followed by the phase velocity that also takes dispersion in mind. The result could then be used to obtain the elastic modulus of the achilles tendon based on group and phase velocity for further comparison.The conclusion was then that the elastic modulus will depend on what kind of velocity it is derived from. This indicates that the shear wave interacts with the organ's boundaries which causes dispersion.

This thesis is comprised of two studies. The objective of the first study was to find the frequency response and stiffness of the biceps brachii muscle group during recovery from exercise induced damage and to determine whether these data could be used to track muscle recovery by correlating changes in the frequency response with changes in muscle stiffness. Stiffness moduli were collected using Shear Wave Elastography (SWE) which were then applied to a proportional first mode frequency analysis. Data were collected for the muscle stiffness and frequency response for fifteen subjects (25.6 +- 4.5). By comparing the proportion of the square root of the SWE results, the variation in stiffness showed a less than 2 Hz change in first mode resonance for the control group. Frequency response results for the control group agreed with the modified SWE results and the proportion analysis. SWE results for the damage protocol group showed an average increase of 4 Hz. Frequency response results for the damage protocol group were sorted into three categories: three subjects had a change in frequency of peaks of at least 4 Hz in the positive direction; four subjects had an increase in amplitude, but no change in frequency of peaks; three subjects showed mixed responses like fewer resonance peaks, variable amplitudes, changes in peak bandwidth. This research allowed for the documentation of the in-vivo frequency response of the biceps brachii muscle. We believe that the frequency response of a muscle group may be used in the future to evaluate recovery from exercise induced damage. Lessons learned were also recorded for helping future studies in their efforts using an SLDV with human body testing.The second study focused on finding the effects on the surface velocity of tissue above and below a region of the lower leg wrapped in an elastic band when excited by an external source. Ten male subjects between the ages of 18-25 were seated in a chair with one foot placed on a vibrating platform. Two excitation frequencies were separately applied while three points along the leg were measured. A repeatability analysis, using results without the leg wrap, showed a 6.5%, 2.5%, and 10.5% variance in the x-, y-, and z-directions respectively, applying a 20 Hz frequency. With a 40 Hz frequency, the variations were 24%, 23.8%, and 28.4% respectively. A change in displacement of +38% and +10% occurred above the knee in the x-direction with 40 Hz and in the y-direction with 20 Hz, respectively. A change in displacement of -20% occurred below the knee in the x-direction with 20 Hz. A change in displacement of -24% occurred below the wrap location in the y-direction with 40Hz. With a confidence interval of 93%, surface velocity of the tissue located above the wrap increased, while the surface velocity of the tissue below the wrap decreased.

No description available.

No description available.

The goal of this work was to quantify the mechanical properties of cellulose nanocrystal (CNC)-based thin films using a polystyrene (PS) structuring approach. This structuring approach was used to biaxially wrinkle CNC-polymer and all-CNC films, in order to assess how changes in the film fabrication process affected the elastic modulus of these films. All films were prepared on pre-stressed PS substrates and structured by heating them above the glass transition temperature of PS, which caused the substrates to shrink and the films to wrinkle biaxially. CNC-polymer films were prepared using the layer-by-layer approach, where three parameters were modified to obtain films of varying compositions: 1) type of polymer (xyloglucan, XG, or polyethyleneimine, PEI), 2) polymer concentration (0.1 wt% or 1 wt%), and 3) film thickness (i.e., number of deposited bilayers). After these films were structured, their elastic moduli were calculated to be 70 ± 2 GPa for CNC-XG0.1, 72 ± 2 GPa for CNC-PEI0.1, and 32.2 ± 0.8 GPa for CNC-PEI1.0 films, indicating that the mechanical properties of CNC-polymer films changed with film composition. This structuring method was also found to provide a humidity-independent measurement of the modulus due to the irreversible nature of the wrinkling. Next, to prepare all-CNC films, CNC suspensions were evaporated under conditions designed to control the film thickness (using 0.005 wt% – 8 wt% CNC suspensions) and CNC nanoparticle orientation (chiral nematic, isotropic, or uniaxial). Suspensions were dried slowly under vacuum, quickly by heating, or by spin-coating to form films with chiral nematic, isotropic, or uniaxial (radial) CNC orientations, respectively. Following structuring, these wrinkled films showed unique morphologies that changed with nanoparticle orientation, suggesting that their mechanical properties are dependent on the CNC orientation within the films. The work presented in this thesis implies that the mechanical properties of films fabricated from hygroscopic bio-based nanomaterials can be assessed in a humidity-independent way by using the structuring method presented. Quantifying the mechanical properties of these films is critical to assess the potential applications of CNCs, where CNC-based materials may be used in developing paper-based electronics, extracellular matrix mimics, and plant cell wall mimics. / Thesis / Master of Science (MSc)

Objetivo: Analisar a influência da matriz orgânica, do conteúdo inorgânico e do tratamento térmico (TT) sobre diferentes propriedades de compósitos experimentais, tais como o grau de conversão (GC), tenacidade à fratura (KIC), resistência à flexão (RF) e módulo de elasticidade (ME). Métodos: Para o experimento foram analisadas seis formulações de compósitos experimentais com proporções molares de Bis-GMA:TEGDMA de 5:5 e 7:3, a carga utilizada foi o vidro de bário, nas concentrações de 30, 50 e 70% em peso, e os fotoiniciadores a amina e canforoquinona. O GC foi analisado através da espectroscopia no infra-vermelho (FTIR) (n=5). A KlC foi avaliada pelo método single-edge notched beam (SENB). As imagens das superfícies de fratura foram capturadas por um estereomicroscópio e a KlC calculada (n=10). A análise da RF e ME foi realizada através do teste dos três pontos (n=10). Para todos os fatores de variação estudados, metade dos espécimes imediatamente após à confecção receberam TT em estufa convencional, a 170º C por 10 minutos e a outra metade não. Após 24 horas, as amostras foram destinadas de acordo com os ensaios realizados. Os dados foram analisados utilizando ANOVA/Tukey para o grau de conversão, tenacidade à fratura e resistência à flexão, e, Kruskal-Wallis para o módulo de elasticidade (=5%). Resultados: Na análise do GC (%) foi observada significância estatística para os três fatores de variação analisados individualmente (monômero, carga e TT), como também, para a interação monômero x TT (p<0,001). Para a KIC e RF, as alterações significantes foram observadas apenas nos três fatores de variação (monômero, carga e TT) analisados individualmente (p<0,001). Para o ME, os fatores individuais (monômero, carga e TT), a interação carga x TT apresentaram significância estatística (p<0,001), bem como a interação monômero x carga (p=0,001). Conclusões: A matriz orgânica e o conteúdo inorgânico dos compósitos experimentais influenciaram o GC, a KIC, a RF e ME, e o TT promoveu melhorias nas propriedades estudadas. / Objective: To analyze the influence of organic matrix, the inorganic content and thermic treatment (TT) on different properties of experimental composites, such as the degree of conversion (DC), fracture toughness (KIC), flexural strength (FS) and elastic modulus (EM). Methods: This experiment analyzed six formulations of experimental composites with 5:5 and 7:3 molar proportions of Bis-GMA: TEGDMA. The load used was barium glass at concentrations of 30, 50 and 70% by weight and the photoinitiators, camphorquinone and amine. GC was analyzed by infrared spectroscopy (FTIR) (n=5). The KIC was evaluated by a \"single-edge notched beam\" (SENB). The images of the fracture surfaces were captured by a stereomicroscope and KIC calculated (n=10). The analysis FS and EM were performed by testing three points (n=10). For all the variation factors studied, half of the specimens immediately after the preparation received TT in conventional oven at 170º C for 10 minutes and the other half not. After 24 hours, the samples were designed according to the tests. Data were analyzed using ANOVA/Tukey the degree of conversion, fracture toughness and flexural strength, and Kruskal-Wallis test for the elastic modulus (=5%). Results: Analysis of GC (%) statistical significance was observed for the three variation factors analyzed individually (monomer, filler and TT), as well as for the interaction monomer x TT (p <0.001). For KIC and FS, significant changes were observed only in the three variation factors (monomer, filler and TT) analyzed individually (p<0.001). For EM, the individual factors (monomer, filler and TT) TT x filler interaction showed statistical significance (p <0.001), as well as the monomer x filler interaction (p = 0.001). Conclusions: The organic matrix and inorganic content of experimental composites influenced the GC, KIC, FS and EM, and the TT caused improvements in the properties studied.

Placas oclusais são dispositivos intraorais utilizados no manejo de pacientes que apresentam desordens do sono, migrânia do tipo tensional e outros. No entanto são os cirurgiões dentistas que predominantemente utilizam as placas oclusais como tratamento do equilíbrio das arcadas dentárias nas disfunções temporomandibulares, prevenção de desgaste dental em pacientes com hábitos parafuncionais e na prevenção de traumas em atletas. Vários métodos têm sido empregados para reforçar resinas acrílicas, como reforço metálico e atualmente a incorporação de diferentes tipos de fibras tais como: carbono, polietileno e vidro. Contudo a adição de fibras de vidro com partículas menores em algumas propriedades mecânicas ainda permanecem desconhecidas. Objetivo: O objetivo desse estudo foi avaliar algumas propriedades mecânicas como a rugosidade de superfície, microdureza, módulo de elasticidade e resistência flexural em resinas acrílicas após a incorporação de fibras de vidro particuladas pré silanizadas. Material e método: Para avaliação das propriedades foram confeccionados vinte e quatro corpos de prova (65 x 10 x 3 mm) de cada marca comercial de resina acrílica, utilizadas para confecção de placas oclusais, Vipi Flash (autopolimerizável), Vipi Wave (termopolimerizável por calor de microondas), Vipi Crill, Lucitone e QC-20 (termopolimerizáveis por calor de banho de água), sendo doze corpos-de-prova controles, e doze experimentais, com adição de 10% em peso de fibras de vidro particuladas (Reforplás S/A, São Paulo, SP, Brasil). Após a realização do acabamento superficial dos corpos de prova com lixas de carborundum e feltros era realizada a avaliação da rugosidade superficial em rugosímetro (Mitutoyo®) com três leituras ao longo dos corpos-de-prova, a microdureza Vickers era analisada em um microdurômetro (Micro Hardness Tester, Shimadzu, Japan) com cinco mensurações em cada corpo-de-prova, e para avaliar os ensaios de resistência flexural e módulo de elasticidade os corpos-de-prova foram avaliados por meio uma máquina de ensaios universal (Emic DL 2000®, Emic, São José dos Pinhais, PR, Brasil), com velocidade de 5mm/min. Os dados foram analisados estatisticamente, usando testes paramétricos e não paramétricos, de acordo com a distribuição da amostra. Resultados: As médias e desvios padrões do teste de rugosidade superficial em Ra foram Vipi Flash sem fibra (0,10 ± 0,03); Vipi Flash com fibra (0,12 ± 0,01); Vipi Wave sem fibra (0,16 ± 0,02); Vipi Wave com fibra (0,13 ± 0,02); Vipi Cril sem fibra (0,12 ± 0,03); Vipi Crill com fibra (0,15 ± 0,03); Lucitone sem fibra (0,10 ± 0,02); Lucitone com fibra (0,09 ± 0,04); QC-20 sem fibra (0,11 ± 0,02) e QC-20 com fibra (0,18 ± 0,03). As médias e desvios-padrão ao teste de microdureza Knoop com relação às marcas comerciais foram: Vipi Flash sem fibra (15,35 ± 0,3); Vipi Flash com fibra (15,51 ± 0,4); Vipi Wave sem fibra (16,60 ± 0,8); Vipi Wave com fibra (17,25 ± 0,9); Vipi Cril sem fibra (17,78 ± 2,27); Vipi Crill com fibra (18,02 ± 1,0); Lucitone sem fibra (15,72 ± 0,3); Lucitone com fibra (16,69 ± 0,6); QC-20 sem fibra (15,91 ± 0,4) e QC-20 com fibra (15,63 ± 0,2). As médias e desvios-padrão ao teste de módulo de elasticidade foram: Vipi Flash sem fibra (2952,76 ± 292,12); Vipi Flash com fibra (3373,49 ± 403,76); Vipi Wave sem fibra (2511,69 ± 304,09); Vipi Wave com fibra (3225,01 ± 248,66); Vipi Cril sem fibra (2745,61± 288,86); Vipi Crill com fibra (3671,67 ± 329,91); Lucitone sem fibra (1904,53 ± 149,05); Lucitone com fibra (3056,87 ± 126,11); QC-20 sem fibra (1913,86 ± 147,80) e QC-20 com fibra (2858,32 ± 185,26). As médias e desvios-padrão ao teste de resistência flexural foram Vipi Flash sem fibra (81,62 ± 4,82); Vipi Flash com fibra (83,98 ± 4,98); Vipi Wave sem fibra (83,52 ± 8,79); Vipi Wave com fibra (88,98± 8,47); Vipi Cril sem fibra (64,17± 5,46); Vipi Crill com fibra (93,37 ± 9,97); Lucitone sem fibra (74,71± 9,43); Lucitone com fibra (87,29 ± 4,73); QC-20 sem fibra (75,80 ± 8,82) e QC-20 com fibra (81,67± 12,97). Conclusão: Conclui-se que a incorporação de fibras provocou alterações em praticamente todas as propriedades analisadas, sendo, portanto facilmente utilizável como um reforço adicional às resinas acrílicas. Com relação à dureza superficial as resinas acrílicas termopolimerizável por banho de água e termopolimerizável por calor de microondas apresentaram maiores valores quando comparados com a resina acrílica autopolimerizável. Além disso, a adição de fibras de vidro particuladas aumentou os valores de rugosidade de algumas resinas acrílicas Vipi Crill, Vipi Flash e Vipi Wave e se manteve constante nas resinas Lucitone e QC-20. A adição de fibra de vidro não aumentou significantemente a microdureza Knoop nos grupos em estudo. Com relação à resistência flexural as fibras de vidro particuladas aumentaram significantemente todos os valores, assim como o módulo de elasticidade das resinas acrílicas reforçadas pela adição de fibras de vidro. / Intraoral Occlusal splints are devices used in the management of patients with sleep disorders, migraine type tension and others. But dentists who are predominantly using the plates as a treatment of occlusal balance of the dental arches in temporomandibular disorders, prevention of tooth wear in patients with habits and prevention of injuries in athletes. Several methods have been used to strengthen acrylic resins, such as metal reinforcement and are currently incorporating different types of fibers such as carbon, polyethylene and glass. However the addition of glass fibers with smaller particles on mechanical properties are still unknown. Objective: The objective of this study was to evaluate some mechanical properties such as surface roughness, hardness, elastic modulus and flexural strength in acrylic resins after the incorporation of glass fiber particulate pre silanized. Methods: To evaluate the properties were made twenty-four specimens (65 x 10 x 3 mm) of each brand of acrylic resin, used for fabrication of occlusal splints, Vipi Flash (self-curing), Vipi Wave (by thermo microwave heat), Vipi CRILL, Lucitone and QC-20 (thermo heat water bath), with twelve specimes controls, and twelve experimental, with the addition of 10 wt% glass fiber particulate (Reforplás S / A, São Paulo, Brazil). After completion of the roughness of the specimens with grit carborundum and felt it was evaluated the surface roughness on roughness tester (Mitutoyo ®) with three readings over the specimes, the microhardness was examined with a hardness ( Micro Hardness Tester, Shimadzu, Japan) with five measurements in each specime, and evaluate the tests for flexural strength and modulus of elasticity of the specimes was evaluated using a universal testing machine (Emic DL 2000 ®, Emic, São José dos Pinhais, PR, Brazil), with speed 5mm/min. The data were statistically analyzed using parametric and nonparametric tests, according to the sample distribution. Results: The mean and standard deviation of the test surface roughness were Vipi Flash without fiber (0.10 ± 0.03); Flash Vipi with fiber (0.12 ± 0.01); Vipi Wave without fiber (0, 16 ± 0.02); Vipi Wave with fiber (0.13 ± 0.02); Vipi Cril without fiber (0.12 ± 0.03); Vipi CRILL with fiber (0.15 ± 0.03); Lucitone without fiber (0.10 ± 0.02); Lucitone with fiber (0.09 ± 0.04), QC-20 fiber without (0.11 ± 0.02) and QC-20 with fiber (0.18 ± 0.03). Means and standard deviations for Knoop microhardness test with respect to trademarks were Vipi Flash without fiber (15.35 ± 0.3); Flash Vipi with fiber (15.51 ± 0.4); Vipi Wave without fiber (16.60 ± 0.8); Vipi Wave with fiber (17.25 ± 0.9); Vipi Cril without fiber (17.78 ± 2.27); Vipi CRILL with fiber (18.02 ± 1.0 ); Lucitone without fiber (15.72 ± 0.3); Lucitone with fiber (16.69 ± 0.6), QC-20 without fiber (15.91 ± 0.4) and QC-20 with fiber (15 , 63 ± 0.2). Means and standard deviations to test elastic modulus were Vipi Flash without fiber (2952.76 ± 292.12); Flash Vipi with fiber (3373.49 ± 403.76); Vipi Wave without fiber (2511.69 ± 304.09); Vipi Wave with fiber (3225.01 ± 248.66); Vipi Cril without fiber (2745.61 ± 288.86); Vipi CRILL with fiber (3671.67 ± 329.91); Lucitone without fiber (1904.53 ± 149.05); Lucitone with fiber (3056.87 ± 126.11), QC-20 without fiber (1913.86 ± 147.80) and QC-20 with fiber (2858.32 ± 185 26). Means and standard deviations for flexural strength were Vipi Flash without fiber (81.62 ± 4.82); Flash Vipi with fiber (83.98 ± 4.98); Vipi Wave without fiber (83.52 ± 8 , 79); Vipi Wave with fiber (88.98 ± 8.47); Vipi Cril without fiber (64.17 ± 5.46); Vipi CRILL with fiber (93.37 ± 9.97); Lucitone without fiber ( 74.71 ± 9.43); Lucitone with fiber (87.29 ± 4.73), QC-20 without fiber (75.80 ± 8.82) and QC-20 with fiber (81.67 ± 12.97). Conclusion: the conclusion is that the incorporation of fibers resulted in changes in almost all properties examined, and thus easily used as an additional reinforcement for acrylic resins. With respect to the surface roughness of acrylic resins by thermo water bath and microwave thermo heat showed higher values when compared with acrylic resin. Moreover, the addition of glass fiber particulate increased the roughness values of some acrylic resins Vipi CRILL, Vipi Flash and Vipi Wave and remained constant in the resins Lucitone and QC-20. The addition of glass fiber does not increase significantly the microhardness in the groups. With respect to flexural strength glass fiber particulate significantly increased all values, as well as the modulus of acrylic resin reinforced by the addition of glass fibers.

A radiação ionizante de fontes de radiação gama ou geradores de raios-x é frequentemente utilizada na ciência médica, como em exames de radiodiagnóstico, radioterapia e esterilização de aloenxertos. A radiação ionizante é capaz de quebrar cadeias polipeptidicas e provocar a libertação de radicais livres, pela radiólise de moléculas de água. A radiação ionizante interage também com o material orgânico a nível molecular, podendo alterar as suas propriedades mecânicas. No caso específico do tecido ósseo, estudos reportam que a radiação ionizante induz alterações nas moléculas de colágeno e reduzem a densidade de ligações cruzadas intermoleculares. O objetivo deste estudo foi verificar as alterações promovidas por diferentes doses de radiação ionizante no tecido ósseo utilizando a técnica de Espectroscopia Transformada de Fourier com Reflexão Total Atenuada (ATR-FTIR), e também a análise dinâmico-mecânica. Amostras de osso bovino foram irradiadas usando irradiador de Cobalto-60, com cinco doses diferentes: 0,01 kGy, 0,1 kGy, 1 kGy, 15 kGy e 75 kGy. Para estudar os efeitos da radiação ionizante sobre a estrutura química do osso foram avaliadas a relação material orgânico por material inorgânico, a relação de sub-bandas de amida I e o índice de cristalinidade. As alterações mecânicas foram determinadas por meio do módulo de elasticidade e do valor do amortecimento. Para verificar se as mudanças químicas e as características mecânicas de osso possuem alguma relação, realizou-se um estudo sobre a correlação entre as análises feitas com os dados espectroscópicos e as análises mecânicas. Foi possível avaliar os efeitos de diferentes doses de radiação ionizante no tecido ósseo. Com a análise por espectroscopia ATR-FTIR, foi possível observar as modificações dos componentes orgânicos e na organização cristais de hidroxiapatita. Também foram observadas alterações no módulo elástico e na tangente de delta (dissipação de energia mecânica). Foram encontradas altas correlações com significância estatística entre a relação das bandas (amida III + colágeno)/v1,v3, PO43- com a tangente de delta, e entre a relação 1/FHMW e o módulo elástico. / Ionizing radiation from gamma radiation sources or X-ray generators is frequently used in Medical Science, such as radiodiagnostic exams, radiotherapy, and sterilization of haloenxerts. Ionizing radiation is capable of breaking polypeptidic chains and causing the release of free radicals by radiolisys.of water. It interacts also with organic material at the molecular level, and it may change its mechanical properties. In the specific case of bone tissue, studies report that ionizing radiation induces changes in collagen molecules and reduces the density of intermolecular crosslinks. The aim of this study was to verify the changes promoted by different doses of ionizing radiation in bone tissue using Fourier Transform Infrared Spectroscopy (FTIR) and dynamic mechanical analysis (DMA). Samples of bovine bone were irradiated using Cobalt-60 with five different doses: 0.01 kGy, 0.1 kGy, 1 kGy, 15 kGy and 75 kGy. To study the effects of ionizing irradiation on the chemical structure of the bone, the sub-bands of amide I, the crystallinity index and relation of organic and inorganic materials, were studied. The mechanical changes were evaluated using the elastic modulus and the damping value. To verify whether the chemical changes and the mechanical characteristics of the bone were correlated, the relation between the analysis made with spectroscopic data and the mechanical analysis data was studied. It was possible to evaluate the effects of different doses of ionizing radiation in bone tissue. With ATR-FTIR spectroscopy, it was possible to observe changes in the organic components and in the hidroxyapatite crystals organization. Changes were also observed in the elastic modulus and in the damping value. High correlation with statistical significance was observed among (amide III + collagen)/v1,v3, PO43- and the delta tangent, and among 1/FHWM and the elastic modulus.

A radiação ionizante de fontes de radiação gama ou geradores de raios-x é frequentemente utilizada na ciência médica, como em exames de radiodiagnóstico, radioterapia e esterilização de aloenxertos. A radiação ionizante é capaz de quebrar cadeias polipeptidicas e provocar a libertação de radicais livres, pela radiólise de moléculas de água. A radiação ionizante interage também com o material orgânico a nível molecular, podendo alterar as suas propriedades mecânicas. No caso específico do tecido ósseo, estudos reportam que a radiação ionizante induz alterações nas moléculas de colágeno e reduzem a densidade de ligações cruzadas intermoleculares. O objetivo deste estudo foi verificar as alterações promovidas por diferentes doses de radiação ionizante no tecido ósseo utilizando a técnica de Espectroscopia Transformada de Fourier com Reflexão Total Atenuada (ATR-FTIR), e também a análise dinâmico-mecânica. Amostras de osso bovino foram irradiadas usando irradiador de Cobalto-60, com cinco doses diferentes: 0,01 kGy, 0,1 kGy, 1 kGy, 15 kGy e 75 kGy. Para estudar os efeitos da radiação ionizante sobre a estrutura química do osso foram avaliadas a relação material orgânico por material inorgânico, a relação de sub-bandas de amida I e o índice de cristalinidade. As alterações mecânicas foram determinadas por meio do módulo de elasticidade e do valor do amortecimento. Para verificar se as mudanças químicas e as características mecânicas de osso possuem alguma relação, realizou-se um estudo sobre a correlação entre as análises feitas com os dados espectroscópicos e as análises mecânicas. Foi possível avaliar os efeitos de diferentes doses de radiação ionizante no tecido ósseo. Com a análise por espectroscopia ATR-FTIR, foi possível observar as modificações dos componentes orgânicos e na organização cristais de hidroxiapatita. Também foram observadas alterações no módulo elástico e na tangente de delta (dissipação de energia mecânica). Foram encontradas altas correlações com significância estatística entre a relação das bandas (amida III + colágeno)/v1,v3, PO43- com a tangente de delta, e entre a relação 1/FHMW e o módulo elástico. / Ionizing radiation from gamma radiation sources or X-ray generators is frequently used in Medical Science, such as radiodiagnostic exams, radiotherapy, and sterilization of haloenxerts. Ionizing radiation is capable of breaking polypeptidic chains and causing the release of free radicals by radiolisys.of water. It interacts also with organic material at the molecular level, and it may change its mechanical properties. In the specific case of bone tissue, studies report that ionizing radiation induces changes in collagen molecules and reduces the density of intermolecular crosslinks. The aim of this study was to verify the changes promoted by different doses of ionizing radiation in bone tissue using Fourier Transform Infrared Spectroscopy (FTIR) and dynamic mechanical analysis (DMA). Samples of bovine bone were irradiated using Cobalt-60 with five different doses: 0.01 kGy, 0.1 kGy, 1 kGy, 15 kGy and 75 kGy. To study the effects of ionizing irradiation on the chemical structure of the bone, the sub-bands of amide I, the crystallinity index and relation of organic and inorganic materials, were studied. The mechanical changes were evaluated using the elastic modulus and the damping value. To verify whether the chemical changes and the mechanical characteristics of the bone were correlated, the relation between the analysis made with spectroscopic data and the mechanical analysis data was studied. It was possible to evaluate the effects of different doses of ionizing radiation in bone tissue. With ATR-FTIR spectroscopy, it was possible to observe changes in the organic components and in the hidroxyapatite crystals organization. Changes were also observed in the elastic modulus and in the damping value. High correlation with statistical significance was observed among (amide III + collagen)/v1,v3, PO43- and the delta tangent, and among 1/FHWM and the elastic modulus.