Objetivo: avaliar a biocompatibilidade de materiais indicados como protetores pulpar no tecido subcutâneo de ratos ao longo do tempo. Métodos: Implantes padronizados de Hidróxido de Cálcio (HC), Cimento de Ionômero de Vidro (CIV) e Adesivo Dentinário Fotoativado (ADF) foram colocados cirurgicamente no dorso de ratos Wistar e deixados por 15 e 30 dias (cada grupo com 5 animais) e os respectivos grupos sham (S). Após a experimentação os animais foram sacrificados e material do dorso dos animais foi retirado para estudo ao microscópio de luz com estereologia e imuno-histoquímica para &#945;-actina de músculo liso (ACML, detecção de miofibroblastos). As pastilhas e a superfície das cápsulas fibrosas foram analisadas quanto a textura, em microscopia eletrônica de varredura (MEV) com microanálise. Resultados: Houve diferenças na fibrose e no número de mastócitos na região peri-implante dependente do tipo de implante. Não foram detectados miofibroblastos expressando ACML. O menor valor de densidade volumétrica de fibrose intersticial (Vv[f]) ocorreu no grupo HC, e o maior no grupo ADF (diferença significativa em relação ao grupo S, nos dois tempos experimentais, p<0,05). Entretanto, aos 30 dias, houve acréscimo de 30% de Vv[f] do grupo ADF, determinando, neste período, diferença significativa em relação ao grupo HC. Quanto a densidade numérica de mastócitos por área (NA[mastócito]) o menor valor ocorreu no grupo HC sem diferença para o grupo S, mas diferença para o grupo ADF (este com o maior valor de NA[mastócito] nos dois tempos experimentais). O grupo CIV apresentou, para Vv[f] e NA[mastócito], durante toda a experimentação, resultados intermediários aos grupos HC e ADF. Houve fibrose discreta e restrita a área cirúrgica com poucos mastócitos juntos aos vasos no grupo S. Houve correlação positiva para Vv[f] e NA[mastócito], no grupo ADF. Ao MEV viu-se interação, no grupo HC, entre o material da pastilha e sua cápsula fibrótica, mas não nos grupos ADF e CIV. Conclusão: Os materiais estudados induziram a formação de fibrose e migração de mastócitos de modo diferenciado. Os resultados sugerem o HC como o material mais compatível biologicamente dentre os testados neste trabalho. / Purpose: to evaluate the biocompatibility of some pulpar protecting materials in the subcutaneous tissue of rats along the time. Methods: standardized implants of Calcium Hydroxide (CH), Glass Ionomer Cement (GIC) and Light-cured Dentin Adhesive (LDA) surgically were put in the back of Wistar rats and left by 15 and 30 days (each group with 5 animals) and the respective sham groups (S). After the experimentation the animals were sacrificed and material from the back of the animals was removed for study with light microscope, stereology and immunohistochemistry for smooth muscle alfa-actin (SMAA, myofibroblast detection). The implants and the fibrous capsule surfaces were analyzed with the scanning electronic microscopy (SEM) adapted with microanalysis. Results: the fibrosis and the number of mastocytes were different in the implant area depending of the implant type. Myofibroblasts were not detected expressing SMAA. The smallest value of the volume density of interstitial fibrosis (Vv[f]) occured in the CH group, and the largest in the LDA group (the difference was significant in relation to the S group, in the two experimental times, p < 0.05). However, to the 30 days, the Vv[f] of the LDA group increase 30%, being different from the CH group in this period. The numerical density of mastocytes per area (NA[mastocyte]) was smaller in the CH group without difference for the S group, but with difference from the LDA group (this group had the largest NA[mastocyte] value in the two experimental times). The GIC group had, for Vv[f] and NA[mastocyte] all experimentation time, intermediary values ranging from CH to LDA values. There was discreet and restricted fibrosis in the surgical area with few mastocytes associated to vessels in the S group. There was positive correlation for Vv[f] and NA[mastocyte] in the LDA group. In the CH group the SEM observed interaction between the implant material and its fibrotic capsule, but not in the LDA and GIC groups. Conclusion: The studied materials induced the fibrosis formation and mastocytes migration in a differentiated way. The results suggest that CH as the most biologically compatible material among the materials tested in this work.

Purpose – The purpose of the study is to understand how a cured meat manufacturing company can succeed with an internal change project when the reason is external triggers from society. With this purpose in mind two research questions have been formulated.    They are formulated as followed:  <li data-leveltext="%1." data-font="Georgia,Segoe UI" data-listid="31" data-aria-posinset="1" data-aria-level="1">Which triggers are the reason for change projects to take place in a cured meat manufacturing company?  <li data-leveltext="%1." data-font="Georgia,Segoe UI" data-listid="31" data-aria-posinset="2" data-aria-level="1">Which factors are crucial for a successful change project in a cured meat manufacturing company?   Method – A case study has been conducted at a cured meat manufacturing company, that previously has been through the work of a change project. 13 semi structured interviews were conducted. The interviewees ranged from top management to workers in the production unit. In addition, all employees received a survey about the change process. On top of this, a document study was conducted. The data that was collected was then analyzed in relation to the theoretical framework and then generated the study’s results.   Findings and discussion – the study’s findings show that there is a connection between trends in society and the effect they have on change project through triggers. These connections in this study has a relation to the Leavitt-Ry-theory (Bakka &amp; Fivelsdal, 2006) and Hughes’ triggers theory (Hughes, 2010). The most visible triggers are politics, environment and socio-culture. Trends in society have a direct connection to the outcome of change projects vision and mission, factors which lead the way in the work of a change project. This shows a connection between trends in society and change projects, because of the four identified key factors of a change project. These four factors are vision &amp; mission, targets &amp; sub-targets, communication &amp; dedication and lastly time.   Limitations – In this study the focus was on one single case. A company that previously had been through the work of a change project. Interviews were held with collective employees that had taken part in the previous change project, although many of the previous participants had quit their job. Therefore, their impressions/experiences were lost. On top of that the documentation from the previous change project were inadequate. These factors together with the fact that the study only had one case in focus made the generalizability a question for discussion.   Keywords – change projects, project, trends, society, vision, communication, cured meat manufacturing company, triggers. / Syfte – Syftet med denna studie är att förstå hur ett charktillverkningsföretag lyckas med ett internt förändringsarbete när anledningen till förändringen är starka externa samhällstriggers.  Med detta syfte i åtanke har det tagits fram två frågeställningar. Dessa frågeställningar lyder:  <li data-leveltext="%1." data-font="Georgia" data-listid="1" data-aria-posinset="1" data-aria-level="1">Vilka triggers finns för förändringsarbeten i ett charktillverkningsföretag?  <li data-leveltext="%1." data-font="Georgia" data-listid="1" data-aria-posinset="2" data-aria-level="1">Vilka faktorer är avgörande för ett förändringsarbete inom ett charktillverkningsföretag?   Metod – Det har genomförts en enfallsstudie på ett charktillverkningsföretag som tidigare har genomfört ett förändringsarbete i organisationen. Det genomfördes 13 semistrukturerade intervjuer med personer i olika position på företaget, allt från högsta ledning till produktionspersonal.  Utöver detta delades det ut en survey till produktionspersonalen där fokus låg på upplevelser från förändringsarbeten. Det gjordes också en dokumentstudie från ett föregegående förändringsarbete. Den data som tagits fram har sedan analyserats i förhållande till det uppställda teoretiska ramverket och har då resulterat i studiens resultat.   Resultat och diskussion – Resultatet av studien visar att det finns ett samband mellan samhällstrender och hur de påverkar organisationer och förändringsarbeten genom triggers. Dessa samband har i denna studien stöd i Leavitt och Ry’s teori (Bakka &amp; Fivelsdal, 2006) och Hughes triggersteori (Hughes, 2010). Dessa triggers är främst politik, miljö och sociala aspekter. Samhällstrender påverkar förändringsarbetets vision och mission, faktorer som genomsyrar företaget och visar vägen för förändringsarbeten. Detta visar på ett samband mellan samhällstrender och förändringsarbeten då de fyra faktorer som är avgörande i förändringsarbeten är vision &amp; mission, mål &amp; delmål, kommunikation &amp; engagemang och tid.   Begränsningar – I denna studie låg det endast fokus på ett fallföretag. Ett företag som tidigare har genomgått ett förändringsarbete. Det genomfördes intervjuer med kollektivanställda som hade varit med i detta tidigare förändringsarbete, men många av de tidigare deltagarna hade slutat och därför gick deras intryck/erfarenheter förlorade. Dessutom var dokumentationen från detta förändringsarbete bristfällig. Detta tillsammans med det faktum att det var en enfallsstudie som utfördes kan sägas ha minskat generaliserbarheten i studien.   Nyckelord – Förändringsarbete, projekt, samhällstrender, omvärlden, vision, kommunikation, charktillverkningsföretag, triggers.

Neste trabalho são reunidos diferentes modelos e técnicas para representar situações experimentais ou observacionais de análise de sobrevivência. Para modelar respostas bivariadas e covariáveis foi proposto o modelo de regressão Kumaraswamy-Weibull bivariado. A presen»ca de indivíduos curados foi considerada sob duas diferentes abordagens, originando o modelo de regressão com fração de cura para dados bivariados por meio de cópulas e o modelo de regressão log-linear bivariado com fração de cura. Os parâmetros dos modelos foram esti- mados pelo método de máxima verossimilhança sujeito a restriçãoo nos parâmetros por meio da função barreira adaptada. Adaptou-se uma análise de sensibilidade de forma a considerar as metodologias de Influência Global, Influência Local e Influência Local Total para verificar vários aspectos que envolvem a formulação e ajuste dos modelos propostos. Utilizou-se um conjunto de dados de insuficiência renal e retinopatia diabética são utilizados para exemplificar a aplicação dos modelos propostos. / This work brought together di®erent models and techniques to represent expe- rimental or observational situations in survival analysis. To model bivariate responses and covariates was proposed Kumaraswamy Weibull bivariate regression model. The presence of cured individuals was considered under two di®erent approaches originating the regression model with a cured fraction for bivariate data through copulas and the log-linear bivariate regression model with cured fraction. The parameters of the models were estimated by ma- ximum likelihood method subject to the restriction on the parameters through the adapted barrier function. A sensitivity analysis was adapted considering the methodologies of Global In°uence, Local In°uence and Total Local In°uence to check various aspects of the formulation and adjustment of the models proposed. Data set of renal failure and diabetic retinopathy are used to exemplify the application of the proposed models.

<p>Transport of gasses and liquids through polymers and composites is an important factor to be considered when designing a material for structure and packaging applications. For structural engineering applications, more focus has been given to the transportation of water, vapor and organic liquids rather than gases as diffusion of these liquids into the polymers and polymer-based composites can significantly lower service life. In addition, much attention has been given to the leaching of unreacted reactant molecules, solvents, additives, degradation products from the polymers and composites to the atmosphere (water, soil etc.). We studied the transport of volatile organic compounds and water in cured-in-place-pipe (CIPP) (a representative of FRPC) and gas permeability of highly engineered cellulose nanocrystals (CNC) films.</p> <p>Cured-in-place-pipe (CIPP) is a popular technology which uses fiber reinforced polymer composite to repair sanitary sewer, stormwater, and drinking water pipe. The liner is installed in the field and exposed to flowing water immediately after installation (curing of the liner) is done. Curing conditions dictate liner properties as undercured liners can contain unreacted styrene monomers, additives, degradation products. These agents can leach out and enter the environment (soil, water, air). The objective of this work was to investigate the curing behavior, volatile content, thermal stability of steam-cured and UV-cured CIPP liners collected from Indiana and New York installation sites. The liner specimens were also exposed to water and other aggressive environmental conditions (saltwater, concrete pore solution at 50 °C) to explore the leaching of unreacted styrene and other organic chemicals from the liners. The influence of transportation of water, salt solution and pore solution through liners on mechanical and thermo-mechanical properties was also examined to study the durability of the liners. Study suggested that the durability of the liners depends on the curing condition and exposed environment conditions.</p> <p>The function of polymer packaging materials is mainly to inhibit gas and moisture permeation through the films. Cellulose nanocrystals (CNCs) have drawn growing interest for the packaging due to their non-toxicity, abundance in nature, biodegradability and high barrier properties. The objective of this work was to corelate the alignment of CNC with free volume and barrier performance of the film. Furthermore, citric acid (CA) was added to the CNC suspensions with varying quantity to explore the effect of CA on coating quality and barrier performance of CNC coated polypropylene (PP) film. Study revealed that CA addition in CNC suspension can enhance the hydrophobicity and gas barrier performance of coated PP films while retaining the high optical transparency. </p>

<p>This dissertation focused on cured-in-place-pipe (CIPP) technology, which is being used to repair sewer pipes across the globe. The CIPP process involves the manufacture of a new fiber-reinforced composite plastic pipe inside an existing damaged pipe. By 2022, the global CIPP market will exceed $2.5 billion and constitute 40% of the U.S. pipe rehabilitation market. In recent years, concerns about the type, magnitude, and toxicity of chemical air emissions associated with CIPP installations have markedly increased. CIPP installations in Asia, Europe, Oceania, and North America have been associated with indoor and ambient air contamination incidents, afflicted schools, daycare centers, homes, and offices and prompted building evacuations. This research program was designed to better understand chemical release into the air during CIPP composite manufacture and the human health risks. Principles and techniques from the environmental engineering, air quality, material science, and risk analysis were applied. This dissertation contains three chapters and each chapter is a stand-alone manuscript, with the first chapter already having been published.</p><p>Chapter 1 involved the characterization of chemical emissions for steam-cured CIPP installations in Indiana (IN, sanitary sewer) and California (CA, storm sewer). It was discovered that a complex multiphase mixture of organic vapor, water vapor, and particulate (condensable vapor and partially cured resin) was emitted. Chemicals captured included a variety of hazardous air pollutants, carcinogens, endocrine disrupting compounds, and other chemicals with little toxicity data. The materials captured in California during 4 CIPP installations, when normalized against styrene concentration, exhibited different toxicity towards mouse cells. This toxicity indicated that non-styrene compounds were probably responsible for toxicity. Testing revealed significant and previously unreported worker and public safety chemical risks existed with CIPP installations.</p><p>Chapter 2 describes experiments conducted to determine which CIPP manufacturing conditions (i.e. curing pressure, temperature, time and ventilation) influenced chemical air emissions during and after composite manufacture. During thermal manufacture, approximately 8.87 wt% volatile organic compounds (VOC) was released into the air at standard pressure. For the CIPP styrene-based resin examined, chemical volatilization during manufacture was influenced by pressure, but temperature and heating time did not influence the composition of chemical residual inside the new composite. All cured composites, regardless of temperature or heating time, contained approximately 3 wt% VOC. No statistical difference was found for either: (1) VOC loading across cured composites or (2) styrene emission into the air across cured composites despite different curing temperature and heating times. Styrene was the most abundant compound detected in the composite and in air. High styrene air concentration signals inhibited the author’s ability to determine if other non-styrene compounds were emitted into the air. Short-term ventilation (2 hr) of the new composite reduced styrene air concentration to near zero in 10 min, but styrene levels rebounded when ventilation was halted. Due to the high styrene loading in the cured composite, it is expected that ventilation will only temporarily reduce VOC air levels in pipes, manholes, and other affected spaces.</p><p>Chapter 3 includes inhalation health risk assessment due to chemical emission from CIPPs during manufacture and use. Publicly available worksite data for ultraviolet (UV)-light and steam-CIPP installations were utilized and Monte Carlo simulation was applied. Data-gaps were also identified. Health risks associated with newly manufactured (post-cured) chemical emission from lab scale CIPPs were also evaluated. For CIPP resins and post-cured CIPPs 31 chemicals have been quantified among which many are unique volatile organic chemicals VOCs, but only 8 air testing studies were found. At a steam-CIPP worksite, VOCs were found in a condensed multiphase mixture discharged into air, 4 VOCs were detected in the vapor phase, while only styrene vapor phase results could be used for risk assessment. Worksite styrene levels (1,825 ppm_v, 1,070 ppm_v, 220-270 ppm_v, 140 ppm_v) have been reported indicating a health risk can exist. Monte Carlo simulation using literature data revealed that for the single UV-CIPP and single steam-CIPP study negligible styrene HQs were found, while unacceptable styrene LECRs% > 10⁻⁴ (i.e. 37-38%) were obtained. Monte Carlo simulation on laboratory data showed that post-cured emissions from the composite cured longer increased the unacceptable styrene LECR (from 17.86% to 21.12%) and HQ (0.95% to 8.04%). Whereas curing the composite at greater temperature reduced the styrene LECR and HQ to 0.89%. and 0, respectively. Ventilation also diminished the acceptable LECR% in all composites but did not reduce the carcinogenic health risk to an acceptable level. Health risk can exist as evidenced by limited air testing data. More studies are needed to examine inhalation health risks associated with the CIPP manufacturing process and newly manufactured plastics.</p>

La domestication est un modèle idéal pour étudier les processus évolutifs car elle implique des événements d'adaptation récents avec une sélection forte. Les champignons sont de bons organismes modèles pour étudier la domestication et plus généralement l’adaptation, grâce à leurs petits génomes et leur facilité de manipulation. Ils sont utilisés depuis longtemps pour la transformation alimentaire, par exemple P. camemberti et P. roqueforti pour la fabrication du fromage, et la levure Saccharomyces pour la fermentation du vin et de la bière. Chez ces champignons, des caractéristiques bénéfiques ont été acquises pour la transformation alimentaire, et les transferts horizontaux de gènes se sont révélés être un moyen essentiel d’adaptation rapide dans l’environnement alimentaire. Ici, j’ai étudié principalement l’adaptation de deux espèces de Penicillium relativement distantes phylogénétiquement - P. nalgiovense et P. salamii, toutes deux utilisées pour la maturation de la viande séchée. J’ai étudié si ces champignons ont été domestiqués, c’est-à-dire si les populations alimentaires se sont adaptées à l’environnement de la viande séchée, et s’il y a eu une différenciation génétique par rapport à d’autres populations; j’ai aussi recherché si des traces génomiques d’adaptation pouvaient être détectées. En analysant des génomes complets, j’ai trouvé peu de diversité génétique et de structure de population chez P. salamii et encore moins chez P. nalgiovense. Des expériences ont montré que les populations de P. salamii et P. nalgiovense provenant de viande séchée présentaient des taux de protéolyse et de lipolyse plus faibles et des couleurs différentes de celles des populations de viande non séchée. De plus, nous avons trouvé des transferts de gènes horizontaux partagés par P. salamii et P. nalgiovense et absents chez d’autres espèces de Penicillium. En résumé, ces résultats indiquent une évolution convergente et une adaptation des populations de P. salamii et P. nalgiovense à la viande séchée. J'ai également étudié les conséquences de la domestication chez le champignon utilisé pour la production de fromages bleus, P. roqueforti, montrant une faible fertilité des souches fromagères par rapport aux souches non fromagères. Les résultats de la thèse soulignent donc l'importance des transferts de gènes horizontaux pour une adaptation rapide chez les champignons et renforcent l'idée que les champignons domestiqués pour la production de nourriture sont de bons modèles pour étudier l'adaptation et l'évolution. / Domestication is an ideal model to study evolutionary processes due to the recent adaptation events and strong selection it implies. Fungi in particular are good model organisms to study domestication and more generally adaptation, with their small genomes and experimental tractability. Fungi have been used for food production, e.g., P. camemberti and P. roqueforti for cheesemaking, and Saccharomyces yeast for wine and beer fermentation. In these fungi, beneficial traits have been acquired for food production, and horizontal gene transfers (HGTs) have been shown to be a major way to rapid adaptation in food environment. Here, I mainly studied the adaptation of food Penicillium fungi using two distantly related Penicillium species - P. nalgiovense and P. salamii, both used for dry-cured meat maturation, to assess whether these fungi have been domesticated, i.e., whether food populations adapted to the dry-cured meat environment, whether were genetically differentiated from other populations, and whether we could find genomic footprints of adaptive events. Using genome sequencing, we found little diversity and population structure in P. salamii and even less in P. nalgiovense. Experiments showed that both P. salamii and P. nalgiovense dry-cured meat populations had lower proteolysis and lipolysis rates and different colors from non-dry-cured meat populations. Furthermore, we found HGTs shared by P. salamii and P. nalgiovense while lacking in other Penicillium species. Altogether, these results indicate convergence evolution and adaptation in P. salamii and P. nalgiovense dry-cured meat populations, as was previously found in cheese Penicillium fungi. I also studied the consequences of domestication in the blue cheese fungus P. roqueforti, showing lower fertility of cheese strains compared to non-cheese strains. The results of the thesis thus point out the importance of HGTs for rapid adaptation in fungi and reinforce the view that fungi are ideal models to study adaptation and evolution.

Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this study was 1) To determine the impact of eliminating or delaying the photo-activation procedure on the polymerization contraction stress (PCS)and degree of conversion (DC) of a dual-cured resin luting agent, and 2) To determine the amount of delay in photo-initiation of the dual-cured resin cements that can achieve a reduced PCS value with the highest possible DC. The amount of PCS and DC of a dual-cured resin luting agent was determined using a tensometer and ATR spectroscopic technique, respectively. Photo-activation delay in seven tested groups was 0 min, 2 min, 4 min, 6 min, 8 min, 10 min and no photoactivation. Five samples for each group were tested. There were two hypotheses for this study: 1) A significant decrease in the amount of PCS associated with delayed photo-activation, and 2) A significant increase in DC associated with delayed photo-activation.The PCS of the chemical-cure luting agent had significantly lower value than all of the light-cure groups. For the light-cure groups, those with a 4-min delay had higher PCS than those with delays of 0 min, 2 min, 6 min, 8 min, and 10 min. The zero (0)-min and 2-min delay had higher PCS than the 6-min, 8-min, and 10-min delay; and the 6-min delay had higher PCS than the 8-min and 10-min delay. The PCS decreased 0.086 MPa per minute of delay. The DC of the chemical-cure luting agent had significantly lower value than the 2-min, 4-min, 6-min, 8-min, and 10-min delaylight cure. For the light-cure groups, 0-min delay had a lower DC than the 2-min, 4-min, 6-min, 8-min, and 10-min delay; 2-min delay had lower DC than 4-min, 6-min, 8-min, and 10-min delay. The 4-min and 6-min delay had lower DC than the 8-min and 10-min delay; and the 8-min delay had a lower degree of conversion by peak area than the 10- minute delay. The DC increased 0.021 per minute of delay. Extending the stress relief period of the dual-cured luting agents by delaying light activation has a significant impact on PCS and DC values. There was significant decrease in PCS with the delayed light curing of the resin luting agent. Significant increase in DC was noticed when light activation was delayed in the dual-cured resin luting agents.

No description available.

Microwave curing has become a trend in composite processing due to its efficiency in energy consumption compared to the traditional curing method. However, as commonly found in every composite processing, controlling the microwave curing process remains challenging. The most feasible control method is to build a numerical model. In this report, the numerical model was developed to simulate the microwave heating of cured and uncured glass/epoxy samples. The objective of cured sample simulation was to obtain the average electric field intensity generated in the composite, which was then used in the uncured sample simulation. Meanwhile, three methods of microwave heating to the uncured samples were suggested, i.e. heating with constant electric field intensity, heating with non-constant electric field intensity, and heating with concentrated electric field intensity. The simulation was further expanded by combining microwave heating with contact heating to improve the curing state on the corner section. The simulation showed a reasonable temperature evolution trend for all three microwave-heated methods of an uncured sample. However, they are all different from the experiment result. Meanwhile, a high temperature in the core layer was observed in all simulations with a gradual temperature decline toward the outer layer, as expected from a microwave heated object. Finally, a decent degree of cure was obtained by employing additional contact heating without involving microwaves. / Mikrovågsbaserad härdning har blivit en trend inom komposittillverkning på grund av dess energieffektivitet jämfört med den traditionella härdningsmetoden. Men precis som i all komposittillverkning är det fortfarande utmanande att kontrollera mikrovågshärdningsprocessen. Den mest genomförbara kontrollmetoden är att bygga en numerisk modell. I den här rapporten utvecklades en numerisk modell för att simulera mikrovågvärmning av härdat och ohärdat glas/epoxiprover. Målet med simuleringen av de härdade proven var att få fram den genomsnittliga intensiteten av det elektriska fältet som genereras i kompositen, vilket sedan användes i simuleringen av de ohärdade proven. Samtidigt föreslogs tre metoder för mikrovågshärdning av de ohärdade proven, nämligen uppvärmning med konstant intensitet av det elektriska fältet, uppvärmning med varierande intensitet av det elektriska fältet och uppvärmning med koncentrerad intensitet av det elektriska fältet. Simuleringen utökades sedan genom att kombinera mikrovågshärdning med kontaktuppvärmning för att förbättra härdningsgraden i hörnsektionen. Simuleringen visade en rimlig temperaturutveckling för alla tre metoder för mikrovågsuppvärmda ohärdade prov. Dock skiljer de sig alla från experimentresultatet. Samtidigt observerades en hög temperatur i kärnskiktet i alla simuleringar med gradvis temperatursänkning mot ytterlagret, vilket förväntas hos ett mikrovågsuppvärmt objekt. Slutligen uppnåddes en acceptabel härdningsgrad genom mot sluret addera kontaktuppvärmning utan mikrovågor.

Este estudo teve como objetivo avaliar os efeitos de variações no protocolo de ativação e envelhecimento acelerado em algumas propriedades de cimentos resinosos de polimerização dual. Adicionalmente, investigaram-se os efeitos da variação da temperatura ambiente e envelhecimento acelerado no tempo de trabalho e tempo de presa dos cimentos quando ativados exclusivamente pela reação química. As propriedades avaliadas foram o grau de conversão, determinado por espectrometria no infravermelho com transformada de Fourier (FTIR-ATR), microdureza Knoop, expressa em KHN, e resistência mecânica à tração expressa em MPa. Os tempos de trabalho e tempos de presa foram determinados por um reômetro oscilatório com controle de temperatura da plataforma de teste estabelecida em 24oC ou 37oC. O envelhecimento acelerado foi determinado pela armazenagem dos cimentos, em suas embalagens originais, e após os testes iniciais, em estufa a 37oC por 12 semanas.A variável de modo de ativação foi determinada em 3 níveis. Os cimentos foram manipulados de acordo com as instruções dos fabricantes e ativados por luz imediatamente (controle), ativados por luz após 10 minutos de reação química no escuro (Exp 1) ou mantidos no escuro por 15 minutos, permitindo a reação química, mas sem fotoativação (Exp 2). Os cimentos tiveram suas propriedades avaliadas em função desses diferentes modos de ativação, antes e após o envelhecimento acelerado. Cimento exclusivamente ativado pela reação química foi empregado como controle quando necessário. Os diversos resultados podem ser resumidos em alguns aspectos de interesse. O tempo de trabalho e o tempo de presa de todos cimentos foram afetados significantemente pela temperatura e envelhecimento (p<0.05). O aumento da temperatura acelerou os tempos de trabalho e presa. Os efeitos do envelhecimento foram materiaisdependentes. Alguns materiais apresentaram redução, enquanto outros apresentaram aumento dos tempos de trabalho e presa, independentemente da variação da temperatura. O modo de ativação e envelhecimento afetaram significantemente as propriedades dos cimentos (p<0.05). Em geral, o grau de conversão aumentou com o tempo após a fotoativação. O retardo da fotoativação por 10 minutos causou alterações no grau de conversão, independentemente do envelhecimento, e para alguns produtos somente. O envelhecimento afetou a cinética da reação química de polimerização dos cimentos. Alguns materiais não apresentaram suficiente reação química após o envelhecimento. As propriedades variaram amplamente de acordo com o modo de ativação e produto. O envelhecimento foi a variável que causou alterações mais significantes e com grande implicação na utilização clínica dos produtos. Alguns materiais se tornaram impróprios para uso após o envelhecimento acelerado. / The study aimed to evaluate the effects of curing protocol and accelerated aging on some properties of dual-cure resin cements. Additionally, the effects of different ambient temperature and aging on the working and setting times were investigated when cements were self-cured only. Properties evaluated were degree of conversion as determined by FTIR-ATR spectroscopy, Knoop microhadness as expressed by KHN, and tensile strength as expressed in MPa. Working time and setting time were determined by an oscilating rheometer with controlled temperature stage at either 24oC or 37oC. Accelerated aging was performed by storing the original product kits in an oven at 37oC for 12 weeks after initial testing had been executed. Different curing protocols were established in 3 levels. Cements were manipulated according to the manufacturers instructions and light-activated immediately (control), light-activated after 10 minutes delay of self-curing in the dark (Exp 1), or simply allowed to self-cure for 15 minutes in the dark (Exp 2). Properties were evaluated according to the different curing protocol and both before and after aging. Exclusively self-curing cement was used as control product when appropriate. The results can be summarized in some aspects of interest. The working time and setting time of all products were significantly affected by temperature and aging (p<0.05). Increased temperature resulted in shorter working time and setting time. The effects of aging were material dependent. Some products presented reduced working and setting times, while others behave otherwise, regardless of the temperature. Curing mode and aging significantly affected the properties of the cements (p<0.05). In general, the degree of conversion increased with time after light-activation. The curing delay for 10 minutes caused alterations in the degree of conversion, regardless of aging, for some products, but not all. Aging affected the curing kinectics and general properties of all cements. Some materials did not present sufficient cure after aging. Properties varied widely according to curing protocol and product. Aging was the variable that most affected the products and the most relevant regarding the clinical use of the materials. Some products were deemed improper for clinical use after accelerated aging.