Isospecific polymerization of styrene with supported nickel acetylacetonate/methylaluminoxane catalysts

Summary The polymerization of styrene with catalysts based on Ni(acac)₂ supported on SiO₂ and Al₂O₃ was investigated. Using catalysts based on MAO supported on silica, a highly isotactic polystyrene was obtained. Nevertheless, the Al₂O₃-supported catalyst can promote isospecific polymerization activated by common. alkyl aluminum compounds even by any prior support treatment with MAO. Received: 3 March 1998/Revised version: 14 April 1998/Accepted: 14 April 1998     

BIO logical agents: Norms,beliefs, intentions in defeasible logic

In this paper we follow the BOID (Belief, Obligation, Intention, Desire) architecture to describe agents and agent types in Defeasible Logic. We argue, in particular, that the introduction of obligations can provide a new reading of the concepts of intention and intentionality. Then we examine the notion of social agent (i.e., an agent where obligations prevail over intentions) and discuss some computational and philosophical issues related to it. We show that the notion of social agent either requires more complex computations or has some philosophical drawbacks.     

Time correlated fluorescence characterization of an asymmetrically focused flow in a microfluidic device

In this study, we explore and model the behavior of a prototype microfluidic device which employs two non-mixing fluids (sheath and inlet fluids) displaying an asymmetric focused flow, in the presence of a fluorescent dye. Fluorescence correlation spectroscopy is employed, allowing the precise measure of flow speeds across the channels and of the concentration profile of the central focused flux along the flow direction. The system is modeled via a standard Navier–Stokes finite-element approach, coupled to convection–diffusion equations for the solute. Simulations reproduce accurately the shape, the position, and the width of the velocity and concentration profiles along the central channel and across the transversal and vertical sections of the microfluidic device. The observed asymmetric flow with respect to the center of the channel is reproduced numerically with an error in the position determination smaller than 1%.     

A semantic enriched data model for sensor network interoperability

One of the main open issues in the development of applications for sensor network management is the definition of interoperability mechanisms among the several monitoring systems and heterogeneous data. Interesting researches related to integration techniques have taken place, they are primary based on the adoption of sharing data mechanisms. In the last years, the Service-Oriented Architecture (SOA) approach has become predominant in many sensor network projects as it enables the cooperation and interoperability of different sensor platforms at an higher level of abstraction. In this paper we propose a novel architecture for the interoperability of sensor networks, which is based on web services technologies and on a common data model enriched with semantic concepts and annotations. The proposed architecture allows the development of complex decision support system applications by integration of heterogeneous data, accessible through services, according to standard data format and standard protocols.     

Segmentation and quantification of COVID-19 infections in CT using pulmonary vessels extraction and deep learning

Multimedia Tools and Applications - At the end of 2019, the World Health Organization (WHO) reported pneumonia that started in Wuhan, China, as a global emergency problem. Researchers quickly...     

Probabilistic rule-based argumentation for norm-governed learning agents

This paper proposes an approach to investigate norm-governed learning agents which combines a logic-based formalism with an equation-based counterpart. This dual formalism enables us to describe the reasoning of such agents and their interactions using argumentation, and, at the same time, to capture systemic features using equations. The approach is applied to norm emergence and internalisation in systems of learning agents. The logical formalism is rooted into a probabilistic defeasible logic instantiating Dung??s argumentation framework. Rules of this logic are attached with probabilities to describe the agents?? minds and behaviours as well as uncertain environments. Then, the equation-based model for reinforcement learning, defined over this probability distribution, allows agents to adapt to their environment and self-organise.     

Partially interactive evolutionary artists

User fatigue is probably the most pressing problem in current Interactive Evolutionary Computation systems. To address it we propose the use of automatic seeding procedure, phenotype filters, and partial automation fitness assignment. We test this approaches in the visual arts domain. To further enhance interactive evolution applications in aesthetic domains, we propose the use of artificial art critics—systems that perform stylistic and aesthetic valuations of art—presenting experimental results. Penousal Machado: He is a researcher at Centre for Informatics and Systems of the University of Coimbra (CISUC). He is the author of more than 20 journals and conference papers, and chair of several international workshops. His main research interest is the study and development of evolutionary approaches to creativity and artificial art. Juan Romero, Ph.D.: He is the founder of the “Creative Computer Group” of the RNASA Lab. His present research focuses on (i) Hybrid Society, which consists of an egalitarian society composed of creative computers and human beings (ii) Artificial Art, using artificial art critics and creators based on connectionist and evolutionary techniques. Amílcar Cardoso, Ph.D.: He is an Associate Professor at the Department of Informatics Engineering of the University of Coimbra. He is the leader of the CISUC AILab, and founder of the Creative Systems Group. His main research interest is the study and implementation of computer models of creativity. He has background as professional musician and composer. Antonino Santos, Ph.D.: He is the author/editor of more than 25 articles and 7 books. He participated as researcher in 7 funded research proposals concerning to Artificial Intelligence, Neural Networks and Internet Security. His present research focuses in hybrid systems, creative systems, computer security, artificial neural networks and evolutionary computation.     

PMMA/o‐MMT nanocomposites obtained using thermally stable surfactants

In the preparation of polymer/montmorillonite (MMT) nanocomposites, the commonly used compatibilizers (cations of long carbon‐chain alkyl ammonium salts) present the drawback of a poor thermal stability. During bulk processing of nanocomposites elevated temperatures are usually required and, if processing temperature is close to decomposition temperature of the surfactant, decomposition will occur altering the interface between filler and polymer. To solve this problem, organically modified MMTs with thermally stable imidazolium surfactants have been prepared. A series of nanocomposites were obtained by dispersing o‐MMT in poly(methyl methacryate) (PMMA) matrix via an in situ free radical polymerization. The nanocomposites were characterized by X‐ray diffraction, transmission electron microscopy, gel permeation chromatography, thermogravimetric analysis, dynamic mechanical analysis, and nanoindentation measurements. The results showed that nanocomposite thermal stability depended on both the kind of used surfactant and degree of exfoliation. Under the same values of molecular weight, the nanocomposites containing imidazolium cations showed a better thermal stability with respect to the nanocomposite obtained using a standard alkylammonium surfactant. Dynamic mechanical and Nanoindentation measurements showed an improvement of mechanical properties, such as modulus and hardness, with respect to pure PMMA. Solution blending treatments on these nanocomposites led to obtaining of further improvement of the thermal performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41393.