Thesis (M.Eng.)(Geotechnical)--University of Pretoria, 2004. / Includes summary. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 101-106). Also available in electronic version.

Orientador: Marco Antonio Compagnoni / Banca: Débora Barros Barbosa / Banca: Renata Garcia Fonseca / Resumo: O estudo avaliou a resistência de união entre dentes artificiais e resinas acrílicas para base protética e o efeito da termociclagem. Para isso foram utilizadas três marcas comerciais de dentes artificiais de resina acrílica (Biotone, Trilux e Ivoclar) e quatro de resinas acrílicas para base protética, sendo duas termopolimerizáveis por banho de água quente (Lucitone 550 e QC-20), uma polimerizada por meio da energia de microondas (Acron MC) e uma fotopolimerizável (Versyo.com). Vinte espécimes foram confeccionados para cada combinação de dente artificial e resina acrílica e divididos em 2 grupos (n=10) nas seguintes condições experimentais: sem a ação da termociclagem (grupo controle) e com a ação da termociclagem. Os espécimes dos grupos com termociclagem foram submetidos 5000 ciclos com temperatura variando entre 4º e 60ºC e tempo de imersão de 30 segundos em cada. Em seguida, os espécimes foram submetidos ao ensaio mecânico de cisalhamento em máquina universal a uma velocidade de 1mm/min. Os dados foram submetidos à análise de variância a três fatores seguida pelo teste de Bonferroni para comparações múltiplas (a=0,05). Os resultados demonstraram que a termociclagem reduziu significantemente os valores médios de resistência de união da resina acrílica Lucitone 550 quando associada aos dentes Biotone e Trilux e com a resina Versyo.com e os dentes Ivoclar P<0,05). E que as médias de resistência de união das resinas acrílicas Acron MC e Lucitone 550 quando associadas aos dentes Ivoclar aumentaram significantemente após a ação da termociclagem (P<0,05). Conclui-se que algumas combinações de dente artificial e resina acrílica podem ser mais afetadas pela ação da termociclagem, e esses efeitos variam de acordo com os materiais selecionados. / Abstract: The purpose of this in vitro study was to evaluate the bond strength of denture base resins to acrylic denture teeth and the effect of the thermocycling. Three acrylic denture teeth (Biotone, Trilux and Ivoclar) were chosen for bonding to four denture base resins: one microwave-polymerized (Acron MC), two heat-polymerized (Lucitone 550 and QC-20) and one light-polymerized (Versyo.com). Twenty specimens were produced for each denture base/acrylic denture tooth combination and were divided into 2 groups (n=10) as follows: without thermocycling (control groups) and thermocycled groups that were submitted to 5,000 cycles between 4º and 60ºC with a dwell time of 30 seconds in each bath. Shear strength tests (MPa) were performed with a universal testing machine at a crosshead speed of 1 mm/min until fracture. Statistical analysis of the results was carried out with 3-way ANOVA and Bonferroni's multiple comparisons post hoc analysis for test groups (a=.05). A significant interaction between denture base resin, acrylic denture teeth and thermocycling (P<.001) was observed. The shear bond strengths of Lucitone 550/Biotone, Lucitone 550/Trilux and Versyo.com/Ivoclar specimens were significantly decreased by thermocycling compared with the corresponding control groups (P<.05). The shear bond strengths of Acron/Ivoclar and Lucitone/Ivoclar specimens significantly increased after thermocycling (P<.05). Some acrylic tooth/denture base resin combinations can be more affected by thermocycling; the effects vary based upon the materials used. / Mestre

New trademarks appear on the dental market every year and it is difficult to determine whether they should be used in clinical praxis or not. Numerous studies have been carried out to investigate different types of materials, trying to declare which material is best suited for a certain type of restorations. The study objective was to investigate if there are any differences in the shear bond strength between a self-adhesive cement and an yttrium oxide-stabilized zirconium dioxide (Y-TZP) and a dental cobalt-chromium alloy (Co-Cr).  The null hypothesis was used. The hypothesis was that the shear bond strengths was the same when cementing the adhesive cement to the dental Co-Cr alloy and the yttrium oxide-stabilized zirconium dioxide. Twenty plastic embedded samples were used in this study, 10 specimens of Co-Cr alloy, and 10 specimens of Y-TZP. The cement was applied, and the specimen were stored in water of 37°C for 24 hr. The tests were performed with an UltraTester™ with the speed of 1 mm / min to measure the shear bond strength (SBS) between the adhesive cement, the Y-TZP and the Co-Cr alloy. The values where then registered. The mean value of the shear bond strength for adhesive cement and Y-TZP was 23.5 MPa, and for Co-Cr alloy 22.8 MPa. No significant difference in shear bond strength were found between the adhesive cement and the Y-TZP and the Co-Cr alloy, after being stored in water for 24 hrs, p &gt; 0.05.

Landfill covers are designed as impermeable caps on top of waste containment facilities after the completion of landfill operations. Geocomposite drain (GD) materials consist of a geonet or geospacer (as a drainage core) sandwiched between non-woven geotextiles that act as separators and filters. GD provides a drainage function as part of the cover system. The stability performance of landfill cover system is largely controlled by the interface shear strength mobilised between the elements of the cover. If a GD is used, the interface shear strength properties between the upper surface of the GD and the overlying soil may govern stability of the system. It is not uncommon for fine grained materials to be used as cover soils. In these cases, understanding soil softening issues at the soil interface with the non-woven geotextile is important. Such softening can be caused by capillary break behaviour and build-up of water pressures from the toe of the drain upwards into the cover soil. The interaction processes to allow water flow into a GD core through the soil-geotextile interface is very complex, and have been defined herein as Capillary Related Interface Breakthrough (CRIB). The infiltration test using small column on CRIB conditions for GD in contact with fine grained soils confirmed the development of capillary break at the interface. The effect of water build-up on the interface leads to soil softening in fine grained soils layer and reduce the interface shear strength hence potential instability of the system. Two series of fine grained soil/GD interface shear strength tests conducted to determine the interface shear strength behaviour for a range of soil water contents. The soil softening at the interface due to soaked behaviour show a reduction in interface shear strength and this aspect should be emphasized in design specifications and construction control. Comparison on the main behaviour using field measurements on the trial landfill cover at Bletchley were conducted to increase confidence in the understanding of the implications for design of cover systems.

Made available in DSpace on 2014-06-11T19:24:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-29Bitstream added on 2014-06-13T20:31:05Z : No. of bitstreams: 1 torres_lms_me_sjc.pdf: 1289584 bytes, checksum: a62d84cf9380d80ba27b908f64260c42 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo in vitro teve como objetivo avaliar a influência das ciclagens térmica e termomecânica na resistência adesiva de bráquetes colados em esmalte bovino com primers convencionais e auto-condicionates. Noventa incisivos bovinos foram aleatoriamente divididos em 2 grupos (G), de acordo com o primer utilizado: XT (n=45) – bráquetes colados com primer convencional (Transbond XT/3M, Unitek); SEP (n=45) – bráquetes colados com primer auto-condicionante (Transbond Plus SEP/3M, Unitek). Após a colagem dos bráquetes, cada grupo foi subdividido em 3 subgrupos (n=15): SC (sem ciclagem) – as amostras não receberam nenhum tipo ciclagem; CT (ciclagem térmica) – as amostras receberam apenas ciclagem térmica (500 ciclos de 50C a 550C); CTM (ciclagem termomecânica) – as amostras receberam ciclagem termomecânica (100.000 ciclos de 50C a 550C). A seguir, foi realizado o teste de cisalhamento em uma máquina de ensaios universal (EMIC) a uma velocidade de 1mm/min com célula de carga de 100kg. Após o descolamento dos bráquetes, amostras de cada grupo foram submetidas à avaliação microscópica em microscópio eletrônico de varredura, a fim de analisar a superfície do esmalte e quantificar o Índice de Adesivo Remanescente (IAR) sobre a superfície. Os resultados mostraram que o grupo SEP apresentou maior resistência adesiva (14,70±4,85 MPa) quando comparado com o grupo XT (11,27±4,48 MPa). Para os grupos XT, a resistência adesiva manteve-se semelhante independente do tipo de ciclagem (SC, 11,44 MPa; CT, 11,20 MPa; CTM,11,19 MPa), enquanto que para os grupos SEP o subgrupo CTM foi o que apresentou maiores valores de resistência adesiva (16,84 MPa), seguido do CT (14,99 MPa) e SC (12,26 MPa). O teste ANOVA - 2 fatores revelou que o efeito interação não é estatisticamente significante; indicando, assim, que o efeito do tipo de ciclagem para o grupo XT é o mesmo... / The aim of this in vitro study was to evaluate the influence of thermal and thermomechanical cycling on shearbond strength of orthodontic brackets bonded with conventional and self-etching primers. 90 bovine incisors were randomly divided into 2 groups (G) according to the primer: XT (n=45) – brackets bonded with conventional primer (Transbond XT/3M, Unitek); SEP (n=45) – brackets bonded with self-etching primer (Transbond Plus SEP/3M, Unitek). After bonding, each group were divided into 3 subgroups (n=15): NC (no cycling) – the specimens did not receive any kind of cycling; TC (thermal cycling) – the specimens received only thermal cycling (500 cycles); TMC (thermomechanical cycling) – the specimens received thermomechanical cycling (100.000 cycles). Next, the shearbond strength test was performed in a universal testing machine (EMIC) at a crosshead speed of 1mm/min. After debonding, specimens of each group were submitted to microscopic evaluation in order to analyze the enamel surface, the adhesive penetration and quantify the Adhesive Remaining Index (ARI). The results showed that the SEP group presented higher bond strength (14,70±4,85 MPa) compared with XT (11,27±4,48 MPa). For XT, the bond strength remained similar despite cycling (NC, 11,44 MPa; TC, 11,20 MPa; TMC,11,19 MPa), meanwhile for SEP, the subgroup TMC showed higher values of bond strength (16,84 MPa), followed by TC (14,99 MPa) e NC (12,26 MPa). 2-way ANOVA test indicated that the interaction effect is not statistically different, so the kind of cycling effect for XT is equal for SEP. But the primer effect (XT vs SEP) is statiscally significant. According to the ARI , the group that presented the highest remaining adhesive on the enamel surface was SEP/TMC (ARI=3). The results showed that self-etching primers can be safely used in orthodontic practice because presents adequate values of bond strength ... (Complete abstract click electronic access below)

O propósito deste estudo foi o de avaliar a influência do sistema adesivo e do envelhecimento na resistência adesiva da interface dentina humana-resina composta. Cento e sessenta terceiros molares extraídos tiveram suas raízes removidas e as coroas seccionadas no sentido mésio-distal. As faces vestibulares foram incluídas em anel de PVC/resina acrílica e divididas em quatro grupos correspondentes aos quatro sistemas adesivos testados: um sistema adesivo de condicionamento total, como controle, Adper Single Bond 2 (ASB 2) (3M ESPE); um sistema adesivo autocondicionante de passo único, Adper Easy One (AEO) (3M ESPE); e dois sistemas adesivos autocondicionantes de dois passos, P90 System Adhesive (P90SA) (3M ESPE), e Clearfill SE Bond (CSEB) (Kuraray). Cada grupo foi dividido em quatro subgrupos correspondentes aos quatro tipos de envelhecimentos artificiais utilizados: termociclagem com 500, 10.000 e 30.000 ciclos e estocagem em água destilada a 37ºC por um ano e, após este período, termociclagem com 500 ciclos. Desta maneira, formou-se 16 subgrupos: ASB2.1, ASB2.2, ASB2.3, ASB2.4; AEO.1, AEO.2, AEO.3, AEO.4; P90SA.1, P90SA.2, P90SA.3, P90SA.4; CSEB.1, CSEB.2, CSEB.3, CSEB.4. Após o envelhecimento artificial padronizado foi realizado o teste de resistência ao cisalhamento ISO TR 11405, usando uma máquina universal de testes EMIC-2000, regulada a 0,5mm/minuto e célula de carga de 200 Kgf. Os resultados foram submetidos à análise estatística de variância (Testes ANOVA, Tukey e Scheffé). Houve diferença estatística significante (p<0,01) para dois fatores de variação (adesivo e envelhecimento) e a interação adesivo x envelhecimento (p<0,01) não apresentou diferença estatística significante. O adesivo Adper Single Bond 2, apresentou maiores valores, enquanto que, o P90 System Adhesive, os menores valores de resistência adesiva ao cisalhamento em relação aos demais sistemas adesivos. A termociclagem de 500 ciclos e a estocagem em água a 37ºC por um ano, seguida de 500 ciclos térmicos apresentaram os mais elevados valores de resistência adesiva, sem diferenças estatísticas significantes, assim com a termociclagem de 10.000 e 30.000 ciclos apresentaram os valores mais baixos. Baseado nestes achados pode-se concluir o sistema adesivo e o envelhecimento influenciaram a resistência ao cisalhamento da interface dentina humanaresina composta. / The purpose of this study was to evaluate the influence of the adhesive system and aging on the bond strength of human dentin-composite resin interface. One hundred and sixty extracted third molars had their crowns removed and the roots sectioned mesiodistally. The buccal faces were included ring PVC/acrylic resin and they were divided into four groups corresponding to the four tested adhesive systems tested. A total etch adhesive system, as controls, Adper Single Bond 2 (ASB 2) (3M ESPE), an all-in-one self-etching adhesive system, Adper Easy One (AEO) (3M ESPE) and two two steps self-etching adhesive systems, P90 System Adhesive (P90SA) (3M ESPE), and Clearfill SE Bond (CSEB) (Kuraray). Each group was divided into four subgroups corresponding to four types of used artificial aging: thermocycling with 500, 10,000 and 30,000 cycles and storage in distilled water at 37°C for one year and after this period, thermocycling with 500 cycles. Thus was formed 16 subgroups: ASB2.1, ASB2.2, ASB2.3, ASB2.4; AEO.1, AEO.2, AEO.3, AEO.4; P90SA.1, P90SA.2, P90SA.3, P90SA.4; CSEB.1, CSEB.2, CSEB.3, CSEB.4. After accelerated aging test was standardized shear bond strength ISO TR 11405, using a universal testing machine (EMIC-2000) set at 0.5 mm/minute and a load cell of 200 kgf. The results were subjected to statistical analysis of variance (ANOVA, Tukey and Scheffe). There was a statistically significant difference (p<0.01) for two factors of variation (adhesive and aging) and not for the interaction adhesive x aging (p<0.01). The adhesive Adper Single Bond 2 showed higher values of shear bond strength, whereas the P90 System Adhesive showed the lowest values of shear bond strength compared to other adhesive systems. The thermocycling regimen of 500 cycles and storage in water at 37°C for one year, followed by 500 thermal cycles showed the highest bond strength values, no statistically significant differences, as well as thermocycling of 10,000 and 30,000 cycles showed the lowest values. Based on these findings it can be concluded the adhesive system and aging affected the shear bond strength of human dentin-composite resin interface.

Orientadores: Luiz Andre Freire Pimenta, Roger William Fernandes Moreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-04T03:50:01Z (GMT). No. of bitstreams: 1 Cavalcante_LarissaMariaAssad_M.pdf: 5129389 bytes, checksum: 69fcb025556b8996ea30007b127e03ca (MD5) Previous issue date: 2005 / Resumo: Neste estudo, procurou-se avaliar a influência de alguns fatores envolvidos durante os procedimentos de fotoativação sobre a adaptação marginal e microdureza de restaurações de resina composta; bem como a interferência das metodologias empregadas para estudos de resistência de união ao substrato dental. Os objetivos deste trabalho, composto por quatro artigos científicos foram: A) avaliar a microinfiltração e microdureza de restaurações de resina composta usando três técnicas de fotoativação (convencional, arco plasma de xenônio e soft-start) e duas diferentes resinas compostas (a microhíbrida Filtek Z250 e a compactável Surefil) (Artigo 1); B) avaliar o efeito de diferentes sistemas de luz - lâmpada halógena, luz de arco plasma de xenônio, laser de argônio e um dispositivo a base de luz emitida por diodo (LEDs) - sobre microinfiltração marginal (Artigo 2) e sobre a formação de fendas e microdureza (Artigo 3) de restaurações com margens em esmalte e em dentina, utilizando-se 3 resinas compostas indicadas para dentes posteriores ¿ a microhíbrida Filtek Z250 e duas compactáveis Surefil e Tetric Ceram HB; C) avaliar o comportamento de dois tipos de sistemas adesivos, um de condicionamento ácido total (Single Bond) e um autocondicionante (Clearfil Liner Bond 2V) quando submetidos a dois testes de resistência de união (microtração e cisalhamento). Os resultados encontrados mostraram que as técnicas de ativação não afetaram a microinfiltração quando foi utilizada uma resina microhíbrida, entretanto, para a resina compactável, as restaurações polimerizadas com a técnica convencional apresentaram microinfiltração similar à técnica soft-start, e menor que aquelas polimerizadas com arco plasma de xenônio (Artigo 1). Entretanto, as resinas compostas e os sistemas de luz não interferiram na penetração do corante, não apresentando diferenças estatísticas entre as margens em esmalte e dentina (Artigo 2). Com relação a formação de fendas, não houve diferença estatística entre os sistemas de luz e as resinas compostas para os preparos cavitários com margem em esmalte; por outro lado, para margens em dentina a resina microhíbrida apresentou as menores fendas quando comparada com as resinas compactáveis, já os sistemas de luz não apresentaram diferenças estatísticas entre si (Artigo 3). Os resultados de microdureza apontaram que a resina composta Tetric Ceram HB apresentou menores médias quando comparada com a Surefil e a Filtek Z250, entretanto, os aparelhos não apresentaram influência nos valores de dureza. Com relação à profundidade de polimerização, as superfícies de topo e meio sempre apresentaram maiores valores comparados com a superfície de base (Artigos 1 e 3). Para avaliação da resistência de união, o teste de microtração detectou diferença entre os sistemas adesivos avaliados, enquanto para o teste de cisalhamento diferenças não foram bservadas (Artigo 4). Pode-se concluir, a partir dos dados destes estudos, que os sistemas de luz não interferiram diretamente na adaptação marginal e na microdureza de restaurações de resina composta, porém a formulação do material restaurador tornou-se um fator significativo de influência das variáveis analisadas, e que a escolha da metodologia a ser empregada pode influenciar na detecção dos resultados / Abstract: The development of new restorative adhesive techniques has continuously advanced resulting in huge changes in the adhesive Dentistry. Thus, in this study it was evaluated the influence of some factors involved during the photoactivation procedures on the marginal adaptation and microhardness of Class II resin composite restorations; it was also investigate the influence of the methodologies used to evaluate the bond strength of adhesive materials to the dental substrate. The aims of this study, composed of four scientific articles were: A) to evaluate the microleakage and microhardness of resin composite restorations using three polymerization techniques (conventional, plasma arc curing and soft-start) and two different resin composites (one microhybrid and one packable) (Article 1); B) to evaluate the influence of four photoactivation systems (halogen (QTH); light emitting diode (LED); argon ion laser (AL) and plasma arc curing (PAC)) on microleakage (Article 2), gap formation and microhardness (Article 3) of class II restorations ¿ at dentin and enamel margins, using a microhybrid Filtek Z250 and two packable resin composites (SureFil and Tetric Ceram HB); C) to evaluate the behavior of two adhesive systems: the self-etching primer Clearfil Liner Bond 2V and the total-etch Single Bond when submitted to two bond strength tests: shear bond strength and microtensile. The results showed that the polymerization techniques - conventional, plasma arc curing and soft-start ¿ did not affect the microleakage when a microhybrid resin composite was used. When a packable composite was used, restorations polymerized with Conventional technique presented similar microleakage to restoration polymerized with soft-start and lower than with plasma arc (Article 1). However, no significant differences were found in the microleakage scores among the photoactivation systems and among resin composites used, marginal adaptation was not significantly affected by location (enamel vs. cementum margins) (Article 2). Related to gap formation, there was no significant difference in gap formation among the curing systems and resin composites at enamel margins. However at the dentin margins, the photoactivation methods did not reveal significant differences, but the microhybrid resin composite presented the best results (Article 3). No statistically significant differences were noted between KHN values of Filtek Z250 and Surefil, but Tetric Ceram HB had the lowest KHN. Occlusal and middle KHN were significantly higher than gingival KHN for all materials (Articles 1 and 3). Article 4 demonstrated that specimens used in the microtensile bond strenght test might provide a more accurate detection of differences among the adhesive systems. These findings suggested that different photoactivation systems may have no effect on the microhardness and gap formation, but the resin composite formulation were found to be a significant determinant factor; and that the methodology chosen may interfere in the detection of data / Mestrado / Dentística / Mestre em Clínica Odontológica

In water depths of 500m to greater than 2,000m, off the West coast of Africa, sediments comprise very soft clays with extremely high water contents and plasticity. In situ CPT and T-bar testing in these areas have identified 'crusts' with undrained shear strengths of up to15kPa at 0.5m depth, before the strength reduces by an order of magnitude to normallyconsolidated strengths by 2m depth. This thesis presents an investigation into the behaviour and origin of these crusts. Mini ball-penetrometer tests on natural cores confirm the crustal strength, and indicate a sensitivity of 3 within the crust. However, pipeline interface tests using the Cam-shear device demonstrate a significant variability in the measured interface friction coefficient. Particularlylow strengths are observed when shearing in an undrained manner on a rough interface. These results are attributed to the heterogeneity of natural samples, and demonstrate the need to better understand the origin of the crust material in relation to interface micro-mechanics. A microbiological investigation of crust material by extracting bacteria DNA from claysamples is described, and identifies the presence of the bacterium, Marinobacter aquaeolei. This bacterium is then used to inoculate sterile samples to determine its ability to produce crustal strength. Through this work, it is concluded that M. aquaeolei is unable to create crustal strength, although extracelluar polysaccharides produced by this bacterium will influence thepermeability of sediments through the clogging of voids. It is therefore also concluded that future geotechnical investigation into marine sediments should consider the presence of bacteriaand their ability to influence the soil properties. Wet sieving of crust material shows that the crust comprises a mixture of burrowing invertebrate faecal pellets and clay. Pellets are found to represent 20% to over 55% of the crust material by dry mass. Individual pellets are shown to exhibit unconfined compressive strengths of between 5kPa and 50kPa, thus demonstrating their strength and robustness. Consolidationbehaviour is governed by the percentage of pellets in natural samples. Based ontheir location, abundance and strength, it is concluded that the origin of crustal strength lies with the presence of burrowing invertebrate faecal pellets. When sheared on rough pipeline interfaces, however, pellets are observed to crush, expelling void-filling fragments that may generatepositive excess pore pressures. Smeared clay produced when shearing natural samplesobstructs the dissipation of pore pressures, which may encourage hydroplaning, and explainthe observation of very low interface friction coefficients. It is therefore suggested that smooth pipelines offer more sliding resistance by minimising the risk of pellet crushing. This thesis proposes that wet sieving of core samples should be undertaken during the site investigationsfor future deep-water, hot-oil pipeline installations to provide design information on both the consolidation and strength behaviour of natural sediments.

This work provides an insight into how the molecular interactions influence macroscale properties of two materials: swelling clay and oil shale. Swelling clays cause enormous damage to infrastructure: buildings, roads, and bridges. Understanding the mechanisms are essential to prevent the detrimental effects and use of these clays for engineering applications. Our group studied the effect of fluid polarity on sodium montmorillonite (Na-MMT) swelling clay mineral using molecular modeling and experiments for bridging the molecular level behavior with the microstructure, swelling pressure, permeability, and compressibility. Various polar fluids (Dielectric Constant 110 to 20) found in landfill leachates are used. Our molecular dynamics (MD) simulations show that the nonbonded interactions of Na-MMT with polar fluids are higher than with low and medium polar fluids. These results are consistent with the results from Fourier transform infrared (FTIR) spectroscopy experiments. The polarity of the fluids and the fluid content influence the interlayer spacing, interlayer modulus, nonbonded interactions, and conformation as well as the shear strength parameters, the angle of internal friction (φ) and cohesion (c). Furthermore, the unconfined compressive strength experiments are used to evaluate the undrained cohesion at various swelling level. The nanomechanical properties, the modulus of elasticity (E) and hardness (H), of the undisturbed dry and saturated Na-MMT at various level of swelling are evaluated using nanoindentation experiments for the first time. The undrained cohesion, modulus of elasticity, and hardness decrease with increase in swelling level. Swelling controls the microstructure of Na-MMT clay, and the clay particles breakdown into smaller sizes with increase in swelling level. The Green River Formation located in the United States is the richest oil shale deposit in the world. Oil shale contains clay minerals, bitumen, and kerogen—a precursor to crude oil. A three-dimensional (3D) kerogen model is built from seven fragments, and the interactions of kerogen with Na-MMT is investigated using MD simulations to understand how the kerogen is bound to the clay mineral. The nonbonded interactions between Na-MMT and kerogen as well as among kerogen fragments are found. This work seeks to develop new methods to extract kerogen economically and efficiently. / Department of Energy (DoE) / Mountain Plains Consortium (MPC) / North Dakota Established Program to Stimulate Competitive Research (ND EPSCoR)