Optimization Of A Large Scale Industrial Reactor Towards Tailor Made Polymers Using Genetic Algorithm

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This paper presents a computational procedure for producing tailor made polymer resins, satisfying customers' needs while operating with maximum profit. The case study is an industrial large-scale polymerization reactor. The molecular properties considered are melt index (MI), which measures the molecular weight distribution, and stress exponent (SE), which is related to polydispersity. An economic objective function is associated to a deterministic mathematical model and the resulting optimization problem is solved by genetic algorithm (GA), a stochastic method. The GA parameters for both binary and real codifications are tuned by means of the design of experiments. Attempting to achieve the global optimum, a hybrid method, which introduces process knowledge into GA random initial population, is proposed. The binary codification performs better than the real GA, especially with hybridization. Results show that the GA can satisfactorily predict tailor made polymer resins with profits up to 25% higher than the industrial practice.14259267CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)CNPq (Conselho Nacional de Pesquisa)FAPESB (Fundacao de Amaro a Pesquisa do Estado da Bahia)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Concepciones previas sobre los procesos y contextos educativos entre aspirantes a profesores de ciencias en educación secundaria

La formación inicial del profesorado de enseñanza secundaria se encuentra en un proceso de cambio en el que resulta necesario seguir investigando sobre todos aquellos aspectos que puedan ayudar a mejorar los nuevos programas de formación. Por ello consideramos conveniente explorar las ideas de los futuros profesores de ciencias sobre los procesos y contextos cognitivos relacionados con el ejercicio de la docencia en educación secundaria y diseñar procesos de formación que tengan en cuenta tales concepciones. En esta línea hemos realizado un estudio, entre futuros profesores de ciencias en formación, donde podemos destacar que muchos sujetos muestran ideas sobre la educación científica próximas al enfoque constructivista y al mismo tiempo presentan una visión pesimista del contexto en el que se desarrolla la actividad del profesorado de enseñanza secundaria

Formation of Atomic Carbon Chains from Graphene Nanoribbons

The formation of one-dimensional carbon chains from graphene nanoribbons is investigated using it ab initio molecular dynamics. We show under what conditions it is possible to obtain a linear atomic chain via pulling of the graphene nanoribbons. The presence of dimers composed of two-coordinated carbon atoms at the edge of the ribbons is necessary for the formation of the linear chains, otherwise there is simply the full rupture of the structure. The presence of Stone-Wales defects close to these dimers may lead to the formation of longer chains. The local atomic configuration of the suspended atoms indicates the formation of single and triple bonds, which is a characteristic of polyynes.Comment: 4 pages, 5 figure

Mentoring Entrepreneurial Networks : mapping conceptions of participants in technological-based business incubators in Brazil

La agenda de la investigación reciente sobre emprendedores incluye el análisis de las estructuras cognitivas de los empresarios de éxito, revelándose como una herramienta importante a la hora de examinar una trayectoria emprendedora. Mediante técnicas de mapas cognitivos, este estudio explora los conceptos de una trayectoria de éxito y la red en sí misma como un todo, para el desarrollo de esta carrera. Fueron estudiados 53 empresarios en siete viveros tecnológicos de la ciudad de Recife, Pernambuco, Brasil. El objetivo específico de este estudio era situar los significados comunes de los emprendedores del vivero teniendo en cuenta las redes de apoyo informal. Este tipo de redes ofrecen apoyo a la carrera empresarial, y el presente estudio examina tanto las características como el modelo conceptual que subyace bajo éstas. La recolección de datos fue realizada por medio de entrevistas a través de la técnica de evocación libre. Los significados comunes indican la existencia de categorías de pensamiento inherentes que fomentan el contexto de la red en el entorno del vivero, especialmente en las redes-mentor. Los resultados refuerzan la interpretación de un modelo mentor informal que emerge de las evocaciones predominantes respecto a una carrera de éxito y de la red en sí misma como promotora de su desarrollo.The recent entrepreneurship research agenda includes the analysis of cognitive structures of successful entrepreneurs, revealing an important tool for the examination of an entrepreneurial career. Using techniques of cognitive maps, this study explores the concepts of a successful career and the network itself, as a whole, for career development. Fifty-three entrepreneurs were studied, in seven technological incubators in the city of Recife, Pernambuco, Brazil. Specifically, this study aimed to map the shared meanings of the incubated entrepreneurs regarding informal support networks. Such networks support the entrepreneurial career and the present study explores the characteristics and the conceptual model that underlies the networks. The data collection was achieved through interviews through a free evocation technique. The shared meanings indicate the existence of inherent thought categories that support network context in the incubator environment, mainly the mentoring networks. The results endorse the interpretation of an informal mentoring model emerging from the dominant evocations concerning a successful career and of the network itself as promoter of career development

Anti-money laundering in the United Kingdom: new directions for a more effective regime

Purpose: This paper aims to provide a more nuanced understanding of the effectiveness of the anti-money laundering (AML) regime in the UK and explore opportunities to improve policy and performance. Design/methodology/approach: Qualitative research design using semi-structured interviews and a focus group with practitioners from both public and private sectors. Findings: This paper identifies preventive measures are underfunded by the public sector; there is a disconnect between the regulatory requirement and the regulators’ supervisory approach leading to the ineffective application of the risk-based approach; and authorities have limited ability to stop low-utility reports. Increased collaboration across institutions and sectors, better utilisation of innovative technologies and a sustainable funding plan are needed to drive a collective response to money laundering. Research limitations/implications: Few practitioners in the industry have the knowledge and expertise to discuss the topic at a strategic level and participants were limited (n = 8). Practical implications: This paper adds to the growing corpus of research showing that the AML regime in the UK is ineffective and needs reform. Social implications: This paper encourages practitioners to improve the AML regime, this research contributes to the reform of the existing measures against financial crime. Originality/value: This paper presents new data from AML practitioners to provide a better understanding of the limitations of the AML regime in the UK

Procedimento de operação, manutenção e verificação de centrífuga JOUAN refrigerada.

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Unraveling the molecular basis of host cell receptor usage in SARS-CoV-2 and other human pathogenic β-CoVs

The recent emergence of the novel SARS-CoV-2 in China and its rapid spread in the human population has led to a public health crisis worldwide. Like in SARS-CoV, horseshoe bats currently represent the most likely candidate animal source for SARS-CoV-2. Yet, the specific mechanisms of cross-species transmission and adaptation to the human host remain unknown. Here we show that the unsupervised analysis of conservation patterns across the beta-CoV spike protein family, using sequence information alone, can provide valuable insights on the molecular basis of the specificity of beta-CoVs to different host cell receptors. More precisely, our results indicate that host cell receptor usage is encoded in the amino acid sequences of different CoV spike proteins in the form of a set of specificity determining positions (SDPs). Furthermore, by integrating structural data, in silico mutagenesis and coevolution analysis we could elucidate the role of SDPs in mediating ACE2 binding across the Sarbecovirus lineage, either by engaging the receptor through direct intermolecular interactions or by affecting the local environment of the receptor binding motif. Finally, by the analysis of coevolving mutations across a paired MSA we were able to identify key intermolecular contacts occurring at the spike-ACE2 interface. These results show that effective mining of the evolutionary records held in the sequence of the spike protein family can help tracing the molecular mechanisms behind the evolution and host-receptor adaptation of circulating and future novel b-CoVs. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology

Ejection force of tubular injection moldings. Part II : a prediction model

The integrated knowledge of the injection molding process and the material changes induced by processing is essential to guarantee the quality of technical parts. In the case of parts with deep cavities, quite often the ejection phase of the molding cycle is critical. Thus, in the mold design stage, the aspects associated with the ejection system will require special consideration. In particular, the prediction of the ejection force will contribute to optimizing the mold design and to guarantee the integrity of the moldings. In this work, a simulation algorithm based on a thermomechanical model is described and their predictions are compared with experimental data obtained from a fully-instrumented mold (pressure, temperature, and force). Three common thermoplastics polymers were used for the tubular moldings: a semicrystalline polypropylene and two amorphous thermoplastics: polystyrene and polycarbonate. The thermomechanical model is based on the assumption of the polymer behavior changing from purely viscous to purely elastic below a transition point. This point corresponds to solidification determined by temperature in the case of amorphous materials and by critical crystallinity for semicrystalline polymers. The model results for the ejection force closely agree with the experimental data for the three materials used