Preparation and characterization of plasticized starch/halloysite porous nanocomposites possibly suitable for biomedical applications

Novel porous bionanocomposites based on halloysite nanotubes as nanofillers and plasticized starch as polymeric matrix were successfully prepared by melt‐extrusion. Foaming was obtained by adding water as natural blowing agent, and by increasing the die temperature. Both the expansion ratio and the porosity increase with increasing die temperature. Addition of high water content allows reducing the foaming temperature. Moreover, the introduction of halloysite has double benefits: these fillers act both as a nucleating agent increasing the porosity and as a barrier agent increasing the proportion of small cells. Foams based on plasticized starch with a blend of glycerol and sorbitol loaded with 6 wt % of halloysite, extruded at 117°C, present the cellular structure and the mechanical properties required for scaffold applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41341.     

Informing aggression–prevention efforts by comparing perpetrators of brief vs. extended cyber aggression

As debate continues over the definition of cyberbullying, an important endeavor is identifying aggression–prevention efforts likely to impact reasons for cyberbullying and the broader phenomenon of cyber aggression. No empirical research has examined whether there are useful prevention-related distinctions between perpetrators of cyberbullying vs. perpetrators of brief cyber aggression. Using an online survey, this study explored perpetrators’ beliefs, emotions, and behaviors related to 72 brief vs. 128 extended episodes of cyber aggression. The most pronounced difference was that more extended-episode perpetrators reported having been hurt by something that happened in cyberspace. One pronounced similarity was that if there had been a news story about the perpetrator doing it, 79% or more of both groups said they would not have felt proud; whereas 63% or more said they would have felt ashamed. Among both groups, 76% or more did not agree with the assertion that there should be no offline consequence for online behavior. The findings support prevention efforts intended to do the following: encourage respect and empathy, facilitate adaptive communication and decision-making skills, promote socially appropriate ways of coping with anger and conflict, and increase knowledge and application of relevant rules and laws.     

ϵ‐caprolactone grafting on a poly(vinyl alcohol‐co‐vinyl acetate) in the melt without added initiator

Polycaprolactone (PCL) grafting on vinyl alcohol‐co‐vinyl acetate) (PVA‐Ac), was investigated in the melt at high temperature (170°C), below the PVA‐Ac melting point, by ring opening polymerization of ?‐caprolactone initiated by metal alkoxyde sites present in PVA‐Ac: no additional initiator was used. The obtained average structures were determined by ¹H NMR. As expected, small grafts, with low average polymerization degree (DP), were obtained, between 4 and 12 h of reaction. These DP are due to exchange reactions between hydroxyl groups and PCL growing chains. The PVA‐Ac was shown to be partially substituted by short PCL grafts. The DP linearly increased with the initial Lactone/PVA‐Ac ratio, and the substituted alcohol sites rate were limited to 63%.It was shown that the used reactive system is characterized by a quazi‐living polymerization mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Model-driven development using UML 2.0: promises and pitfalls

Experience indicates that effective complexity management mechanisms automate mundane development tasks and provide strong support for separation of concerns. For example, current high-level programming languages and integrated development environments provide abstractions that shield developers from intricate lower-level details and offer automated support for transforming abstract representations of source code into faithful machine-executable forms. The Object Management Group initiated the Unified Modeling Language 2.0 effort to address significant problems in earlier versions. While UML 2.0 improves over earlier versions in some aspects, its size and complexity can present a problem to users, tool developers, and OMG working groups charged with evolving the standard.     

Chitosan‐based nanofibers as bioactive meat packaging materials

Shelf life and safety of minimally processed food are crucial for both consumers and the food industry. This study investigates the in vitro and in situ efficiency of electrospun chitosan‐based nanofibers (CNFs) as inner part of a multilayer packaging in maintaining the quality of unprocessed red meat. Activated CNF‐based packaging (CNFP) were obtained by direct electrospinning of chitosan/poly(ethylene oxide) solutions on top of a conventional multilayer food packaging. The electrospinning solutions were firstly characterized at the molecular level, mainly in terms of zeta potential and viscoelastic properties, and the evolution of the conformational structure was correlated to the nanofiber formation process. The oxygen and water vapor barrier properties of CNF‐based (CNFP) meat packaging were also investigated. The in vitro antibacterial activity of CNFs was determined against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Listeria innocua, bacteria commonly incriminated in the alteration of food products. The efficiency of the CNFP materials against meat spoilage by E. coli was also assessed. Our results indicate that the electrospinning of CS is a multifactorial process and fiber formation requires the choice of a good solvent, high electrical conductivity, moderate surface tension, optimum viscoelastic properties, and sufficient chain flexibility and entanglement. The results also indicate that all the tested bacterial strains were significantly sensitive to the action of CNFs. The in situ bioactivity against E. coli showed the potential of CNFP as bioactive nanomaterial barriers to meat contamination by extending the shelf life of fresh meat up to 1 week.     

Connection admission control of MPEG streams in ATM network using hierarchical fuzzy logic controller

Asynchronous transfer mode (ATM) operates in a connection-oriented mode; if sufficient resources are not available for transporting data over a network, the connection is refused. Connection admission control (CAC) deals with the question of whether or not an ATM switch can accept a new connection. This paper presents the design of a fuzzy logic controller (FLC) for CAC of Motion Picture Experts Group (MPEG) audio and video streams in an ATM network. Our approach is different from the plain use of sample input–output data for automating FLC design as frequently reported in the literature. One of the differences is that we do not use any sample data that happen to be available. Instead, we perform intensive simulations of the system, to generate sample data which are then processed to obtain unique entries for the selected combination of the values of the input variables. We compared the performance of our fuzzy-CAC to conventional CACs such as those based on average bandwidth, peak bandwidth and equivalent bandwidth and we found our scheme to produce better results.     

CMAS 3D,a new program to visualize and project major elements compositions in the CMAS system

CMAS 3D, developed in MATLAB^®, is a program to support visualization of major element chemical data in three dimensions. Such projections are used to discuss correlations, metamorphic reactions and the chemical evolution of rocks, melts or minerals. It can also project data into 2D plots. The CMAS 3D interface makes it easy to use, and does not require any knowledge of Matlab^® programming. CMAS 3D uses data compiled in a Microsoft Excel? spreadsheet. Although useful for scientific research, the program is also a powerful tool for teaching.