OBJECTIVES: To test and compare the effects of static and cyclic loading on fracture toughness (K1C) and microhardness of dental restorative CAD/CAM materials. MATERIAL AND METHODS: Five commercially available CAD/CAM restorative materials were included in this study: Lava™ Ultimate Restorative (3M ESPE), IPS Empress® CAD (Ivoclar Vivadent), Enamic® (VITA), IPS e.max® CAD (Ivoclar Vivadent), and CERASMART™ (GC Dental). Polished rectangular bars 4×2×14 mm (n=30) were prepared from mill blocks for each material. Single notch of 0.5-1 mm in depth was made on the center of one length edge. Ten specimens per group for each material were randomly selected for 1) static mode, 2) after 100k cyclic loads, and 3) after 200k cyclic loads. The survival bars after the fatigue test were then subjected to a three-point flexural test. K1C values were determined on ‘single-edge-pre-crack-beams’ (SEPB) method. In addition, random specimens after the flexural test were selected for Vickers microhardness test from each group. Additionally indentation fracture method (IF) was used to determine surface fracture toughness for e.max CAD and Empress CAD. All the results were analyzed via ANOVA with Tukey’s HSD test or least square regression model using JMP Pro 12.0. RESULTS: The mean fracture toughness (K1C) of the material tested in static mode (3.2 MPa.m1/2 for e.max CAD, 2 MPa.m1/2 for Lava Ult, 1.95 MPa.m1/2 for Empress CAD, 1.92 MPa.m1/2 for Enamic, and 1.65 MPa.m1/2 for Cerasmart). The 100k fatigue group (4.02 MPa.m1/2 for e.max CAD, 3.06 MPa.m1/2 for Cerasmart, 2.55 MPa.m1/2 for Lava Ult, 2.01 MPa.m1/2 for Enamic, 1.94 MPa.m1/2 for Empress CAD) The 200k fatigue group (3.14 MPa.m1/2 for Cerasmart, 2.83 MPa.m1/2 for Lava Ult, 2.68 MPa.m1/2 for e.max CAD, 2.01 MPa.m1/2 for Enamic, 1.72 MPa.m1/2 for Empress CAD). While there was a significant difference in the mean fracture toughness (K1C) and (VHN) after fatigue of material tested (p<0.05). CONCLUSION: The CAD/CAM materials tested exhibited a higher K1C values after cyclic loading, along with lower K1C compared to the static group. In addition, K1C values by IF method exhibit lower K1C values after fatigue that was not a good way to test the fracture toughness value. / 2018-09-28T00:00:00Z

>Magister Scientiae - MSc / The tuberculosis (TB) disease to this day remains one of the world’s prominent killerdiseases. Pyrazinamide (PZA) is one of the most commonly prescribed anti- tuberculosis (anti-TB) drugs due to its ability to significantly shorten the TB treatment period from the former nine months to the current six months duration. However, excess PZA in the body causes hepatotoxicity and damages the liver. This hepatotoxicity, together with the resistance of the bacteria to treatment drugs, poor medication and inappropriate dosing, greatly contribute to the high incidents of TB deaths and diseases that are due to side effects (such as liver damage). This brings about the calls for alternative methods for ensuring reliable dosing of the drug, which will be specific from person to person due to inter-individual differences in drug metabolism. A novel biosensor system for monitoring the metabolism of PZA was prepared with a Ni-PPI-PPy star copolymer and cytochrome P450 2E1 (CYP2E1) deposited onto a platinum electrode. The nanobiosensor system exhibited enhanced electro-activity that is attributed to the catalytic effect of the incorporated star copolymer. The biosensor had a sensitivity of 0.142 µA.nM-1, and a dynamic linear range (DLR) of 0.01 nM-0.12 nM (1.231 – 7.386 ng/L PZA). The limit of detection of the biosensor was found to be 0.00114 nM (0.14 ng/L) PZA. From the HPLC peakconcentration (Cmax) of PZA determined 2 h after drug intake is 2.79 – 3.22 ng.L-1,which is very detectable with the nanobiosensor as it falls within the dynamic linear range.

Masters of Science / South African dams and reservoirs are increasingly showing the propensity to support sustained populations of Cyanobacteria (blue green algae). These photosynthetic bacteria occur throughout the world and can rapidly form blooms in eutrophic water systems. The occurrence of these photosynthetic bacteria, in our dwindling drinking water source dams, poses a serious, economic, as well as a health, threat to and arid country like South Africa due to is potential to produce of toxic metabolites like Microcystins and Nodularins (MCN). MCN's are cyclic peptides toxins, harmful to humans and animals, and its toxicological mechanism is based on a strong inhibition of protein phosphatises in the liver. This may lead to severe liver damage and increased tumour development. Rural communities consuming untreated water in South Africa are most at risk due the high toxicity of MCN’s at low doses.We endeavour to develop an immunosensor for the detection of Microcystins and nodularins using anti-sheep IgG antibody labelled with horseradish peroxidase (HRP) immobilised on a modified glassy-carbon polymer surface. The immunosensor will be applied to water samples for MCN’s as a group of compounds recognised by the ADDA moiety common to all MCN congeners. The immunosensor will provide immediate confirmation and quantification of MCN’s in situ. A competitive Enzyme Linked Immuno-Sorbant Assay (ELISA) and High Performance liquid Chromatography (HPLC) will be used to validate results of our immunosensor. Elisa's are widely used as a screening test method for MCN's. The antibody-antigen specificity forms the bases for the recognition of target compound (MCN's) by antibodies which bind to a compound which is labelled with a colour indicator, and quantified by spectrophotometry.

Este trabalho apresenta os procedimentos composicionais das peças Murlidhar, Mahakal, Miniatura e O ciclo do tempo. Sendo esta ultima a principal, devido as ferramentas composicionais terem sido experimentadas com maior liberdade. As peças deste projeto utilizaram mitos e ritos do hinduísmo e conceitos da filosofia do Raja Yoga como motivadores para a imaginação sonora e para o desenvolvimento de técnicas de estruturação. Destaca-se, entre as técnicas utilizadas, a que denominei estrutura de ritmos cíclicos, cuja elaboração teve como referência o time point system de Miltton Babbitt. / This paper presents the compositional procedures of Murlidhar, Mahakal, Miniature and The Cycle of Time, the latter being the main piece because the compositional tools have been used with more freedom. The pieces of this project utilized Hinduism myths and rites and Raj Yoga Phylosophy concepts as motivators to the sound imagination and for the development of structuring techniques. Standing out among the techniques used is the one I called Cyclic Rhythms Structure, which had as a reference for its making Milton Babbitt’s time point system.

Este trabalho apresenta os procedimentos composicionais das peças Murlidhar, Mahakal, Miniatura e O ciclo do tempo. Sendo esta ultima a principal, devido as ferramentas composicionais terem sido experimentadas com maior liberdade. As peças deste projeto utilizaram mitos e ritos do hinduísmo e conceitos da filosofia do Raja Yoga como motivadores para a imaginação sonora e para o desenvolvimento de técnicas de estruturação. Destaca-se, entre as técnicas utilizadas, a que denominei estrutura de ritmos cíclicos, cuja elaboração teve como referência o time point system de Miltton Babbitt. / This paper presents the compositional procedures of Murlidhar, Mahakal, Miniature and The Cycle of Time, the latter being the main piece because the compositional tools have been used with more freedom. The pieces of this project utilized Hinduism myths and rites and Raj Yoga Phylosophy concepts as motivators to the sound imagination and for the development of structuring techniques. Standing out among the techniques used is the one I called Cyclic Rhythms Structure, which had as a reference for its making Milton Babbitt’s time point system.

Dans le lagon de Moorea, en Polynésie Française, nous avons identifié un écosystème constitué de deux producteurs primaires (les cyanobactéries filamenteuses Lyngbya majuscula et Anabaena cf. torulosa), trois mollusques herbivores (Stylocheilus striatus, S. longicauda, et Bulla orientalis), un nudibranche carnivore (Gymnodoris ceylonica) et un crabe carnivore (Thalamita coerulipes). L. majuscula et A. cf torulosa prolifèrent sur de vastes zones jusqu’à épiphyter les coraux ; elles sont des producteurs importants de métabolites secondaires, principalement des lipopeptides cycliques, qui peuvent être toxiques ou répulsifs. Cependant, ces composés n’empêchent pas le lièvre de mer S. striatus de consommer les cyanobactéries. S. striatus, décrit comme un prédateur spécialiste de L. majuscula, est connu pour séquestrer et/ou biotransformer les métabolites secondaires de L. majuscula. Cependant nous avons également observé S. striatus, sur A. cf torulosa où il semble moins exposé à la prédation du nudibranch G. ceylonica que quand il est sur L. majuscula. Dans cet écosystème modèle, nous avons combiné le profilage des métabolomes des deux cyanobactéries et des expériences en écologie dans le but d’étudier le rôle des médiateurs chimiques dans la structuration de cet écosystème ; nous avons complété la caractérisation des profils métaboliques des deux cyanobactéries, étudié les transmissions verticale et horizontale des métabolites secondaires produits par les cyanobactéries le long de la chaine trophique, et étudié le rôle de ces composés dans les relations prédateurs-proies. De A. cf torulosa, nous avons isolé cinq analogues acyliques et deux analogues cyliques des laxaphycines que nous avons caractérisés par RMN (1D et 2D RMN : COSY, TOCSY, HSQC, HMBC, NOESY), spectrométrie de masse (spectrométrie de masse à haute résolution et fragmentation en MSn), ainsi que par dégradation chimique avec la méthode de Marfey. La présence de laxaphycines acycliques n’a jamais été décrite auparavant. Nous avons montré que les peptides de L. majuscula sont séquestrés sans biotransformation par les herbivores, alors que les herbivores présents sur A. cf torulosa biotransforment deux laxaphycines en quatre composés nouveaux que nous avons caractérisés. Il ne semble pas que la séquestration et la biotransformation soient opérées dans le but d’améliorer les défenses chimiques des herbivores mais plutôt comme un mécanisme de tolérance. Nous avons également montré que les mollusques herbivores utilisent les composés produits par les cyanobactéries comme signaux chimiques pour détecter à distance les cyanobactéries et pour le choix de leur nourriture. Ces expériences de choix semblent indiquer que S. striatus et B. orientalis sont des herbivores généralistes bien que l’influence des molécules des cyanobactéries suggère un comportement adaptatif permettant au mollusque de retrouver l’hôte sur lequel il a été prélevé. / In the lagoon of Moorea in French Polynesia, we have identified a relatively simple tropical marine ecosystem consisting of two primary producers (two filamentous cyanobacteria, Lyngbya majuscula and Anabaena cf. torulosa), three herbivorous molluscs (Stylocheilus striatus, S. longicauda and Bulla orientalis), a carnivorous nudibranch (Gymnodoris ceylonica) and a carnivorous crab (Thalamita coerulipes). L. majuscula and A. cf torulosa, that bloom ephemerally across wide sandy areas and even on corals, are prolific producers of secondary metabolites, mainly cyclic lipopeptides, which may either be toxic or act as feeding deterrents to potential consumers. However, these compounds do not prevent the sea hare S. striatus, feeding on cyanobacteria. S. striatus, considered as L. majuscula specialist, is known to sequester and transform some secondary metabolites produced by L. majuscula,. However we found also S. striatus feeding on A. cf torulosa and in this case it was less susceptible to predation by the nudibranch G. ceylonicasa than when it fed on L. majuscula. In the study of this model ecosystem, we combine cyanobacterial metabolome profiling and ecological bioassays in order to study the cascading effects of chemical mediators in multi-trophic relationships; we completed the metabolic profile characterization of the two cyanobacteria, we studied vertical and horizontal transmissions of the cyanobacterial secondary metabolites along the trophic web, and studied the role of these compounds in predator-prey relationships. Focusing our attention on A. cf torulosa we isolated seven new lipopeptides, derived from the known laxaphycins, and characterized them using extensive NMR experiments (1D and 2D NMR: COSY, TOCSY, HSQC, HMBC, NOESY), mass spectrometry (HR-MS and fragmentation by MSn) and Marfey’s advanced method. It is the first time that acyclic analogs of laxaphycins have been described. Although the peptides from L. majuscula are found intact in herbivores, some lipopeptides from A. cf torulosa are biotransformed by sea hares into four new compounds we characterized. The sequestration and biotransformation by the herbivores may be considered as a tolerance mechanism rather than a defense mechanism. We demonstrate also that the herbivores use cyanobacterial compounds as chemical cues for cyanobacteria tracking and feeding choice. Our experiments suggest that S. striatus and B. orientalis are generalist consumers, although the influence of cyanobacterial chemical cues on their foraging preferences may suggest an adaptive behavior enabling the mollusc to track their host of origin.

As reduções eletroquímicas dos complexos de ferro(II) FeL32+, com ligantes diimínicos alifáticos, L=CH3-N=C(R)-C-(R\')=N-CH3, onde R,R\' = H,H; H,CH3; CH3,CH3; e ligantes diimínicos mistos, L = C5H4N-C(R\')=N-(R\"), onde R\',R\"= H,CH3; CH3,CH3 foram estudadas através de polarografia e voltametria cíclica em acetonitrila em perclorato de tetraetilamônio 0,2M a 25,0&#186;C. Utilizam-se eletrodo plano de platina.ou eletrodo gotejante de mercúrio como eletrodos de trabalho para a voltametria cíclica e polarografia, respectivamente. Os eletrodos auxiliar e de referência são fio de platina e Ag/AgCl , respectivamente. Os polarogramas obtidos para esses complexos no intervalo de potenciais de 0,0 a -2,4 V vs Ag/AgCl mostram duas a quatro ondas de redução. As duas primeiras etapas são controladas por difusão e os processos de eletrodo podem ser descritos como monoeletrônicos e reversíveis, com a estabilização dos baixos estados de oxidação Fe(I) e F:(0) em acetonitrila. Para o derivado R,R\' = H,CH3, observam-se três ondas reversíveis e monoeletrônicas indicando a estabilização do complexo com ferro no estado de oxidação formal (-I).Comportamento semelhante foi encontrado para complexos de ferro(II) com 2,2\'-dipiridina e 1,10 fenantrolina (. Electrochim. Acta. 13. 335 (1968) ). A estabilização dos baixos estados de oxidação deve-se ao caráter aceptor de elétrons dosoligantes diimínicos, como indicado pelo espectro de transferência de carga e,depende da presença do grupo cromofórico. Verifica-se ainda que quanto maior o valor de 10 Dq, maior a retrodoação e, maior a estabilização dos baixos estados de oxidação. Os voltamogramas cíclicos apresentam dois a três picos de redução no intervalo de potenciais de 0,0 a - 2,2V vs Ag/AgCl. A primeira etapa de redução é bem caracterizada como processo monoe1etrônico e reversível Na redução dos derivados alifáticos R,R\' = H,H; CH3.CH3; há um grande aumento da corrente de pico e os potenciais são deslocados cerca de 0,18V para regiões mais negativas. Isso é interpretado em termos de adsorção do reagente na superfície do eletrodo de platina. É interessante notar que apenas os complexos. que apresentam substituintes simétricos adsorvem na superfície do eletrodo. / The electrochemical reduction of the iron(II) complexes, FeL32+ with aliphatic diimine ligands, CH3-N=C(R)-C(R\')=N-CH3, where R,R\'= H,H; H,CH3; CH3,CH3, and mixed diimine ligands. L = C5H4N-C(R\')=N(R\"), where R\',R\" = H, CH3; CH3,CH3, was studied by means of polarography, and cyclic voltammetry in acetonitrile containing 0,2M tetraethylammonium perchlorate at 25,0&#186;C. A platinum disk or a dropping mercury electrode were used as working e1ectrodes for the cyclic voltammetric and polarographic experiments, respectively. A platinum wire and Ag/AgCl were employed as auxiliar and reference electrodes, respectively. The polarograms obtained for these complexes in the 0.0 to -2,4 V vs Ag/AgCl potential range exhibit two to four reduction waves. The first two reduction waves were shown to correspond to reversible one electron reductions yielding stable complexes of iron in the formal oxidation states (I) and (O). For the derivative R\',R\" = H,CH3, three reversible one electron waves were found, indicating the stability of the complex with iron in the formal oxidation state (-I). A similar be havior has been found for the 2,2\'-dipyridine and 1,10-phenan -throline complexes of iron(II) (Electrochim. Acta,.13, 335(1968)). The stabilization of the low valence states is due to the strong acceptor properties of the diimine ligands. This acceptor character is reflected in the appearence of a characteristic intense inverse charge transfer band in the visible region. in the presence of the diimine chromophore. Increased stabilization of the low oxidation states is correlated with an increase in the magnitude of the ligand-field strength (10 Dq), i.e., increased back-donation. Two or three reduction peaks were observed in the cyclic voltammograms in the region of 0.0 to -2.2 V vs Ag/AgCl. The first reduction of the aliphatic derivatives R,R =\' H,H ; CH3, CH3, there is a large increase in peak currents and a shift of 0.18 V to more negative potentials. This is interpretable in terms of the platinum electrode, It is interesting to note that only the complexes which have symmetrical ligands exhibit adsorption at the electrode surface.

O presente estudo teve como objetivo avaliar a resistência à fadiga cíclica de dois diferentes sistemas rotatórios de níquel-titânio, K3 (Sybron Endo, EUA) e Endosequence (Brasseler, EUA), fundamentando-se no número de usos. Todas as limas rotatórias que foram selecionadas possuíam conicidade 0.04, 25 mm de comprimento e diâmetro de ponta 25, padrão ISO. Para tal logro, um dispositivo desenvolvido especificamente para executar ensaios dinâmicos foi utilizado. Cada grupo foi subdividido em quatro subgrupos em função do número de usos, sendo estabelecidos da seguinte maneira: grupos A0 e B0, instrumentos sem nenhum uso; grupos A1 e B1, instrumentos de um único uso; grupos A3 e B3, instrumentos de três usos e grupos A5 e B5, instrumentos de cinco usos. Cada subgrupo era composto por 12 limas, totalizando 96 instrumentos rotatórios entre K3 e Endosequence. A simulação foi realizada em canais artificiais de resina com curvatura de 40 graus e raio de 5 mm. Todas as limas foram submetidas a ensaios de fadiga cíclica realizados em um dispositivo experimental que permitiu que o instrumento reproduzisse uma instrumentação rotatória em canais curvos. Esse dispositivo possui um temporizador, que registra o tempo de avanços em segundos, desde o início do movimento até a fratura da lima e também um contador, que registra dentro do intervalo de tempo o número de ciclos realizados pelo cilindro pneumático até o momento da fratura. Foi utilizada uma peça de mão com contra-ângulo redutor de 16:1, acionado por motor elétrico na velocidade de 350 rpm e 2 Ncm de torque. O tempo foi registrado por meio do contador presente no dispositivo. Os valores foram transformados em segundos. Para análise estatística, empregou-se o teste de análise de variância (dois critérios) entre as amostras testadas e observou-se que não houve diferença estatisticamente significante em relação ao número de usos. Entretanto, o sistema K3 apresentou maior resistência à fadiga flexural em relação ao sistema Endosequence (p < 0,05). / The aim of this work was to evaluate the cyclic fatigue resistance of two different nickel-titanium rotary systems, K3 (Sybron Endo, EUA) and Endosequence (Brasseler, EUA), based on the number of uses. All rotary files which were selected had their conicity of 0,04, 25mm of length and tip diameter of 25, following ISO standardization. To reach the purposes, a specially developed apparatus to perform dynamic assays was employed. Each group was subdivided into 4 subgroups according to the number of uses, being established as follows: groups A0 and B0, instruments without any use; groups A1 and B1, instruments of a single use; groups A3 and B3, instruments of three uses and groups A5 and B5, instruments of five uses. Each subgroup was compound of 12 files, totalizing 96 rotary instruments between K3 and Endosequence. The simulation was conducted in resin artificial canals presenting curvature of 40 degrees and radius of 5 mm. All files were submitted to cyclic fatigue assays performed on an experimental apparatus where the instrument could reproduce a rotary instrumentation in curved canals. This equipment contains an timer, which records advance time per seconds, since the begin of movement until the file fracture, and also has a counter which registers, on a period of time, the cycle number accomplished by the pneumatic cylinder until the fracture time. A reducer contra-angle hand piece of 16:1 was used, activated by an electric motor on a speed of 350rpm and 2 Ncm of torque. Time was recorded by the counter coupled in the apparatus. Values were converted into seconds. The two-way analysis of variance was employed to statistical evaluation, among tested samples and we could observe that no statistical differences were found in relation to the number of uses. However, the K3 system showed higher resistance to flexural fatigue when compared to the Endosequence system (p < 0,01).

Modelos constitutivos são relações matemáticas entre grandezas físicas que buscam descrever o comportamento dos materiais quando submetidos a ações externas. A hipoplasticidade é um modelo constitutivo desenvolvido para solos a partir de uma modificação da equação hipoelástica. Este modelo tem como principais características a existência de uma única equação constitutiva e o seu caráter não linear, o que lhe confere a propriedade de introduzir deformações irreversíveis desde o início das ações externas. Neste trabalho são estudados dois novos modelos desenvolvidos com o objetivo de melhorar as previsões para carregamentos cíclicos. O primeiro, denominado hipoplasticidade estendida, é caracterizado pela introdução de superfícies de memória e uma nova equação constitutiva específica para o recarregamento. O segundo modelo, a hipoplasticidade cíclica, é uma modificação deste último onde são introduzidos fatores capazes de modificar as superfícies de memória. Os novos modelos são primeiramente aplicados em situações teóricas para verificar sua aplicabilidade. Posteriormente, utilizando dados experimentais, é feita sua calibração e aplicação para então compararem-se as previsões teóricas com os resultados experimentais. Verifica-se que os novos modelos contemplam avanços significativos na previsão do comportamento dos solos sob carregamentos cíclicos. Para permitir um número maior de simulações foi desenvolvida uma planilha eletrônica com a capacidade de representar quantos ciclos sejam desejados, efetuar a alteração dos parâmetros do solo durante a calibração do modelo de maneira fácil e rápida, assim como visualizar para cada um dos intervalos se foi utilizada a equação geral ou a específica do recarregamento. / Constitutive models are mathematical relationships between physical quantities that approximate the behavior of materials when subjected to external actions. Hypoplasticity is a constitutive model developed for soils from a modification of the hypoelastic equation. The main features of this model are the existence of a unique constitutive equation and its nonlinear character, which gives it the property of introducing irreversible deformation from the beginning of external actions. In this work two new models developed in order to improve the predictions of cyclic loading are studied. The first one, which is called extended hypoplacity, has as its main feature the addition of a memory surface and the introduction of a new equation specific for reloading. The second model, cyclic hypoplasticity, which is a modification of this last one, is characterized by the introduction of factors that are capable of modifing the memory surfaces. The new models are first checked in theoretical situations to verify their applicability. Subsequently, using experimental data, the models are calibrated, applied, and then compared to experimental results. The new models include significant advances in predicting soil behavior under cyclic loading. To allow a larger number of simulations, a spreadsheet was developed with the following abilities: simulate as many cycles as are desired; easy to change soil\'s parameters during the calibration phase; and display for each of the intervals which of the equations was used.

Este trabalho apresenta os procedimentos composicionais das peças Murlidhar, Mahakal, Miniatura e O ciclo do tempo. Sendo esta ultima a principal, devido as ferramentas composicionais terem sido experimentadas com maior liberdade. As peças deste projeto utilizaram mitos e ritos do hinduísmo e conceitos da filosofia do Raja Yoga como motivadores para a imaginação sonora e para o desenvolvimento de técnicas de estruturação. Destaca-se, entre as técnicas utilizadas, a que denominei estrutura de ritmos cíclicos, cuja elaboração teve como referência o time point system de Miltton Babbitt. / This paper presents the compositional procedures of Murlidhar, Mahakal, Miniature and The Cycle of Time, the latter being the main piece because the compositional tools have been used with more freedom. The pieces of this project utilized Hinduism myths and rites and Raj Yoga Phylosophy concepts as motivators to the sound imagination and for the development of structuring techniques. Standing out among the techniques used is the one I called Cyclic Rhythms Structure, which had as a reference for its making Milton Babbitt’s time point system.