Fracture load of 3D printed PEEK inlays compared with milled ones, direct resin composite fillings, and sound teeth

Objective!#!The objective of this in vitro study was to investigate fracture load, fracture types, and impact of chewing simulation of human molars restored with 3D printed indirect polyetheretherketone (PEEK) inlays and compare these with milled indirect PEEK inlays, direct resin composite fillings, and sound teeth.!##!Materials and methods!#!A total of 112 molars with form congruent class I cavities were restored with (n = 16/group) 3D printed indirect PEEK inlays via fused layer manufacturing (FLM): (1) Essentium PEEK (ESS), (2) KetaSpire PEEK MS-NT1 (KET), (3) VESTAKEEP i4 G (VES), (4) VICTREX PEEK 450G (VIC), (5) milled indirect PEEK inlays JUVORA Dental Disc 2 (JUV), and (6) direct resin composite fillings out of Tetric EvoCeram (TET). Sound teeth (7) acted as positive control group. Half of the specimens of each group (n = 8) were treated in a chewing simulator combined with thermal cycling (1.2 million × 50 N; 12,000 × 5 °C/55 °C). Fracture load and fracture types of all molars were determined. Statistical analyses using Kolmogorov-Smirnov test and two-way ANOVA with partial eta squared (η!##!Results!#!ESS and TET demonstrated the lowest fracture load with a minimum of 956 N, whereas sound molars showed the highest values of up to 2981 N. Chewing simulation indicated no impact (p = 0.132). With regard to Weibull modulus, KET presented a lower value after chewing simulation than JUV, whereas TET had the highest value without chewing simulation. All indirect restorations revealed a tooth fracture (75-100%), direct resin composite fillings showed a restoration fracture (87.5%), and 50% of the sound teeth fractured completely or had cusp fractures.!##!Conclusions!#!All 3D printed and milled indirect PEEK inlays as well as the direct resin composite fillings presented a higher fracture load than the expected physiological and maximum chewing forces.!##!Clinical relevance!#!3D printing of inlays out of PEEK via FLM provided promising results in mechanics, but improvements in terms of precision and esthetics will be required to be practicable in vivo to represent an alternative dental material

Thickness dependent exchange bias in martensitic epitaxial Ni-Mn-Sn thin films

A thickness dependent exchange bias in the low temperature martensitic state of epitaxial Ni-Mn-Sn thin films is found. The effect can be retained down to very small thicknesses. For a Ni50Mn32Sn18 thin film, which does not undergo a martensitic transformation, no exchange bias is observed. Our results suggest that a significant interplay between ferromagnetic and antiferromagnetic regions, which is the origin for exchange bias, is only present in the martensite. The finding is supported by ab initio calculations showing that the antiferromagnetic order is stabilized in the phase

Evaluation of direct restorations using the revised FDI criteria

Objectives The purpose of this in vitro reliability study was to determine the intra- and inter-examiner agreement of the revised FDI criteria including the categories "fracture of material and retention" (F1) and "caries at restoration margin" (B1). Materials and methods Forty-nine photographs of direct tooth-coloured posterior (n = 25) and anterior (n = 24) restorations with common deficiencies were included. Ten dental experts repeated the assessment in three blinded rounds. Later, the experts re-evaluated together all photographs and agreed on a reference standard. Statistical analysis included the calculation of Cohen's (C kappa), Fleiss' (F kappa), and weighted Kappa (w kappa), the development of a logistic regression with a backward elimination model and Bland/Altman plots.Results Intra- and inter-examiner reliability exhibited mostly moderate to substantial C kappa, F kappa, and w kappa values for posterior restorations (e.g. Intra: F1 C kappa = 0.57, w kappa = 0.74; B1 C kappa = 0.57, w kappa = 0.73/Inter F1 F kappa = 0.32, w kappa = 0.53; B1 F kappa = 0.41, w kappa = 0.64) and anterior restorations (e.g. Intra F1 C kappa = 0.63, w kappa = 0.76; B1 C kappa = 0.48, w kappa = 0.68/Inter F1 F kappa = 0.42, w kappa = 0.57; B1 F kappa = 0.40, w kappa = 0.51). Logistic regression analyses revealed significant differences between the evaluation rounds, examiners, categories, and tooth type. Both the intra- and inter-examiner reliability increased along with the evaluation rounds. The overall agreement was higher for anterior restorations compared to posterior restorations.Conclusions The overall reliability of the revised FDI criteria set was found to be moderate to substantial

Recomendações técnicas para a produção de arroz irrigado em sistema orgânico em Santa Catarina

O arroz irrigado em Santa Catarina possui grande importância econômica e social. O cereal é cultivado em cerca de 150 mil hectares, distribuídos por 83 municípios da faixa litorânea catarinense e do Vale do Itajaí. O arroz catarinense é beneficiado no próprio Estado, com destaque para a produção industrial de arroz parboilizado.  Nos últimos anos, tem se tornado crescente o apelo para a produção agrícola  sustentável e diversas tecnologias dos sistemas produtivos tem sido  adaptadas para a conservação ambiental. Nesse contexto, se insere a produção de arroz em sistema orgânico, não apenas como opção de cultivo de baixo impacto ambiental, mas também para a oferta de produtos com maior segurança alimentar. O desenvolvimento de tecnologias para viabilizar  o cultivo orgânico de arroz irrigado tem sido foco da pesquisa oficial. Em Santa Catarina, os estudos se iniciaram na década de 1990, na Estação Experimental da Epagri de Itajaí, com a implementação de um projeto Embrapa/Prodetab, específico para a produção de arroz em sistema orgânico de cultivo. Novo impulso foi dado em 2009, no sul do estado, com apoio da Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina (Fapesc); tornando-se o Centro de Treinamento da Epagri de Araranguá (Cetrar), o polo irradiador das tecnologias para cultivo orgânico de arroz irrigado em Santa Catarina.  O Sistemas de Produção Recomendações técnicas para a produção de arroz irrigado em sistema orgânico em Santa Catarina reúne as tecnologias básicas  para o cultivo de arroz irrigado em sistema orgânico e é destinado a técnicos, estudantes e aos cerca de 8,5 mil agricultores vinculados a essa cultura. A publicação também é utilizada como guia em cursos e treinamentos realizados pela Epagri sobre a cultura do arroz irrigado.

an empirical study in the German automotive Industry

Opportunismus ist ein zentrales Problem zwischenbetrieblicher Beziehungen. Die Gefahr einer radikalen Nutzenmaximierung auf Kosten des Partners erhöht Transaktionskosten, fördert die Anzahl zwischenbetrieblicher Konflikte und vermindert die gemeinsame Beziehungsleistung. Die vorliegende Dissertation hat das Ziel, einen theoriegeleiteten, hypothesentestenden Erklärungsbeitrag von Partneropportunismus in Geschäftsbeziehungen zu leisten. Sie fragt deshalb erstens nach Art und Wirkung transaktionskostentheoretisch fundierter Treiber partneropportunistischer Verhaltensweisen und zweitens nach der Wirkung eines aus formalen, relationalen und sich selbst durchsetzenden Mechanismen bestehenden Absicherungsdesigns zur wirksamen Einschränkung dieser schädigenden Verhaltensweisen. Die Einbettung dieser Fragestellungen erfolgte in einen theoretischen Bezugsrahmen, der sich hauptsächlich aus transaktionskostentheoretischen Überlegungen, aber auch Argumentationssträngen der Social Exchange Theory konstituiert. Damit wird die ubiquitäre Opportunismusannahme des Transaktionskostenansatzes aufgegeben und Opportunismus stattdessen als nur eine mögliche von vielen denkbaren Verhaltensweisen der Kooperationspartner betrachtet, die über den Einsatz verschieden gelagerter Mechanismen bewusst beeinflusst werden kann. Daten aus 124 Hersteller-Zulieferer-Beziehungen der deutschen Automobilindustrie belegen den Einfluss von Leistungsambiguität, Transaktionsfrequenz sowie verschiedenen Formen von Faktorspezifität und Umweltunsicherheit auf das Ausmaß partneropportunistischer Verhaltensweisen. Als wirksame Mittel zur Begrenzung von Partneropportunismus konnten vor allem die Reputation des Partners, die Aussicht auf eine zukünftige Zusammenarbeit sowie die gemeinsame Vergangenheit mit dem Partner identifiziert werden. Formale Verträge erwiesen sich hingegen als wenig wirkungsvoller Absicherungsmechanismus. Die Ergebnisse zeigen darüber hinaus, dass formale und relationale Vertragsregime keine einfachen Substitute darstellen und unterschiedliche Fähigkeiten aufweisen, partneropportunistische Verhaltensweisen zu begrenzen: Während der Gefahr von Leistungsambiguität im Rahmen eines formalen Vertragsregimes wirkungsvoll begegnet werden kann, erweist sich das relationale Vertragsregime als besonders effektiv, die von verschiedenen Formen der Umweltunsicherheit ausgehenden Gefahren zu vermindern.Transaction cost theory (TCT) particularly emphasizes the importance of the detrimental force of opportunism in interorganizational relationships (IOR). According to Williamson (1985), opportunismus is defined as „self-interest seeking with guile.“ Thus, opportunistic behaviour not only raises conflicts and severely damages the relationship between the partners but also seriously raises transactions costs in IOR. Consequently, partner opportunism reduces potential benefits IOR might offer. Although opportunistic behavior significantly influences the stability of the cooperation and has far-reaching implications for the IOR performance, research on antecedents and influence factors of opportunistic behavior is still limited. The present study aims at filling this research gap and asks, first, which antecedents contribute to opportunism in interorganizational relationships and analyses, second, which formal, relational and self-enforcing factors are most suitable to dampen the negative effect of such antecedents on opportunistic behaviors. The basic TCE assumption of ubiquitous assumption of opportunism is relinquished in favor of the perception that opportunistic behavior represents only one of many possible behavior options. Along with this newer perspective, the logic of TCT and relational exchange theory is interwoven, and a theoretical framework with testable hypotheses is derived. These hypotheses are tested on a sample of 124 buyer-supplier relationship in the German automotive industry. The results of the multiple regression and subgroup analyses show that opportunism does indeed increase with high performance ambiguity, high transaction frequency, some types of asset specificity and environmental uncertainty. Concerning the moderating effects, the study finds that reputation of the partner, shadow of the future, shadow of the past and the possibility to threat the reputation of the partner considerably reduce the negative effect of the aforementioned antecedents on opportunism. In contrast, formal contracts are not effective in reducing opportunistic behavior. In addition, the results also indicate that formal and relational contracting regimes are not simply substitutable but that more intricate mechanisms might be at work. For example, the effectiveness of a relational governance regime as a safeguard against opportunism is robust to external uncertainty but not to ambiguity. Conversely, a formal governance regime is robust to ambiguity but not to volatility. In conclusion, this dissertation provides a theoretical contribution in analyzing what drives opportunism in interorganizational relationships and therewith fills an existing gap in management research. It further provides important managerial implications as it unveils how organizations can protect themselves against partner opportunistic behavior