Shock wave study and theoretical modeling of the thermal decomposition of c-C4F8

The thermal dissociation of octafluorocyclobutane, c-C4F8, was studied in shock waves over the range 1150-2300 K by recording UV absorption signals of CF2. It was found that the primary reaction nearly exclusively produces 2 C2F4 which afterwards decomposes to 4 CF2. A primary reaction leading to CF2 + C3F6 is not detected (an upper limit to the yield of the latter channel was found to be about 10 percent). The temperature range of earlier single pulse shock wave experiments was extended. The reaction was shown to be close to its high pressure limit. Combining high and low temperature results leads to a rate constant for the primary dissociation of k1 = 1015.97 exp(-310.5 kJ mol-1/RT) s-1 in the range 630-1330 K, over which k1 varies over nearly 14 orders of magnitude. Calculations of the energetics of the reaction pathway and the rate constants support the conclusions from the experiments. Also they shed light on the role of the 1,4-biradical CF2CF2CF2CF2 as an intermediate of the reaction.Fil: Cobos, Carlos Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Hintzer, K.. Dyneon Gmbh; AlemaniaFil: Sölter, L.. Universität Göttingen; AlemaniaFil: Tellbach, E.. Universität Göttingen; AlemaniaFil: Thaler, A.. Dyneon Gmbh; AlemaniaFil: Troe, J.. Universität Göttingen; Alemania. Max-Planck-Institut fu¨r biophysikalische Chemie; Alemani

Design of a Virtual Assistant to Improve Interaction Between the Audience and the Presenter

This article presents a novel design of a Virtual Assistant as part of a human-machine interaction system to improve communication between the presenter and the audience that can be used in education or general presentations for improving interaction during the presentations (e.g., auditoriums with 200 people). The main goal of the proposed model is the design of a framework of interaction to increase the level of attention of the public in key aspects of the presentation. In this manner, the collaboration between the presenter and Virtual Assistant could improve the level of learning among the public. The design of the Virtual Assistant relies on non-anthropomorphic forms with ‘live’ characteristics generating an intuitive and self-explainable interface. A set of intuitive and useful virtual interactions to support the presenter was designed. This design was validated from various types of the public with a psychological study based on a discrete emotions’ questionnaire confirming the adequacy of the proposed solution. The human-machine interaction system supporting the Virtual Assistant should automatically recognize the attention level of the audience from audiovisual resources and synchronize the Virtual Assistant with the presentation. The system involves a complex artificial intelligence architecture embracing perception of high-level features from audio and video, knowledge representation, and reasoning for pervasive and affective computing and reinforcement learning to teach the intelligent agent to decide on the best strategy to increase the level of attention of the audience

Falloff curves and mechanism of thermal decomposition of CF3I in shock waves

The falloff curves of the unimolecular dissociation CF3I (+Ar) - CF3 + I (+Ar) are modelled by combining quantum-chemical characterizations of the potential energy surface for the reaction, standard unimolecular rate theory, and experimental information on the average energy transferred per collision between excited CF3I and Ar. The (essentially) parameter-free theoretical modelling gives results in satisfactory agreement with data deduced from earlier shock wave experiments employing a variety of reactant concentrations (between a few ppm and a few percent in the bath gas Ar). New experiments recording absorption–time signals of CF3I, I2, CF2 and (possibly) IF at 450–500 and 200–300 nm are reported. By analysing the decomposition mechanism, besides the unimolecular dissociation of CF3I, these provide insight into the influence of secondary reactions on the experimental observations.Fil: Cobos, Carlos Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Sölter, L.. Universität Göttingen; AlemaniaFil: Tellbach, E.. Universität Göttingen; AlemaniaFil: Troe, J.. Universität Göttingen; Alemania. Institut Max Planck fuer Bioanorganische Chemie; Alemani

Difference in Structure and Electronic Properties of Oxygen Vacancies in α-Quartz and α-Cristobalite Phases of SiO2

α-cristobalite (α-C) is a polymorph of silica, mainly found in space exploration and geochemistry research. Due to similar densities, α-C is often used as a proxy for amorphous SiO2, particularly in computer simulations of SiO2 surfaces and interfaces. However, little is known about the properties of α-C and its basic oxygen defects. Using density functional theory (DFT) simulations we provide a comprehensive report on the properties of perfect structure and oxygen vacancies in α-C. The calculated properties of α-C are compared with those of the better-characterized α-quartz (α-Q). Our results demonstrated that the positively charged O vacancy in α-C is most stable in the dimer configuration, in contrast to α-Q, which favors the puckered configuration. A back-projected configuration was also predicted in both polymorphs. We calculated the optical transition energies and isotropic hyperfine constants for O vacancies in both α-Q and α-C, and compared our findings with the results of previous studies and experiments. This work, thus, offers one of the first in-depth investigations of the properties of oxygen vacancies in α-C

Composición de ácidos grasos de la carne de capones de raza Mos y estirpes comerciales sacrificados a diferentes edades

Se ha estudiado la influencia de la raza [Mos (raza española autóctona), Sasso T-44 y X-44 (estirpes comerciales)] y la edad (5, 6, 7 y 8 meses) de los capones (gallos castrados) en la composición de ácidos grasos de la carne de la pechuga y del muslo. La carne de los capones de raza Mos presentó menor concentración de ácidos grasos monoinsaturados y mayor de poliinsaturados que la carne de las otras razas. Además, dichos capones mostraron mayor contenido de los ácidos margárico (C17:0) y esteárico (C18:0) que las estirpes comerciales; sin embargo, no hubo diferencias significativas entre las distintas razas en el total de ácidos grasos saturados. La carne de los animales más jóvenes mostró menor concentración de ácidos grasos monoinsaturados y mayor de poliinsaturados que la de los animales de mayor edad. Sin embargo, la edad influyó menos que la razaThe influence of the breed [Mos (Spanish indigenous breed), Sasso T-44 and X-44 (commercial strains)] and the age (5, 6, 7 and 8 months) of capons (castrated male cockerels) on the fatty acid compositions of breast and drumstick meat were studied. The meat of the Mos capons showed lower contents of monounsaturated fatty acids and higher concentrations of polyunsaturated fatty acids than those of the other breeds. In addition, the Mos breed showed higher contents of margaric acid (C17:0) and stearic acid (C18:0) as compared to the commercial strains; however, no significant effects of breed were observed in the total contents of saturated fatty acids in the meat. The meat of the youngest animals showed lower contents of monounsaturated fatty acids and higher concentrations of polyunsaturated fatty acids than that of the older ones. Nevertheless, the effect of age was less important than the effect of breedThis study was financially supported by project PGIDIT04RAG012E [Consellería de Innovación, Industria e Comercio da Xunta de Galicia and Asociación de Criadores de Capón de Vilalba]S

Shock wave study and theoretical modeling of the thermal decomposition of c-C4F8

The thermal dissociation of octafluorocyclobutane, c-C4F8, was studied in shock waves over the range 1150-2300 K by recording UV absorption signals of CF2. It was found that the primary reaction nearly exclusively produces 2 C2F4 which afterwards decomposes to 4 CF2. A primary reaction leading to CF2 + C3F6 is not detected (an upper limit to the yield of the latter channel was found to be about 10 percent). The temperature range of earlier single pulse shock wave experiments was extended. The reaction was shown to be close to its high pressure limit. Combining high and low temperature results leads to a rate constant for the primary dissociation of k1 = 1015.97 exp(-310.5 kJ mol-1/RT) s-1 in the range 630-1330 K, over which k1 varies over nearly 14 orders of magnitude. Calculations of the energetics of the reaction pathway and the rate constants support the conclusions from the experiments. Also they shed light on the role of the 1,4-biradical CF2CF2CF2CF2 as an intermediate of the reaction.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The role of Internet in the development of future software projects

Purpose – The Internet has evolved, prompted in part by new Web 2.0 technologies, to become a more widespread platform for interaction, communication, and activism. Virtual communities, or groups of people informally bound together by shared expertise, synthesise this Internet evolution and theWeb 2.0 technology. Users increasingly want to engage online with one another and with organisations of all kinds. These novel Internet-based technologies dominate the new business models of the digital economy giving companies radical new ways to harvest the talents of innovators working outside corporate boundaries. One of the most illustrative examples of this new trend is the Open Source Software (OSS) projects development. This paper aims to analyse the structure and topology of the virtual community supporting one of the most successfully OSS projects, Linux. The objective is to provide conclusions for being successful in the development of future virtual communities. As companies learn to manage these virtual communities, they will develop smarter and faster ways to create value through them. Design/methodology/approach – The interactions of the virtual community members of an ARM-embedded Linux project website is analysed through social network analysis techniques. The participants’ activity is studied and some conclusions about the participation features are obtained using the Gini coefficient. In particular, a participation inequality behaviour or a concentration on a small number of developers is clearly observed. Findings – The paper deals with the guidelines that virtual communities should follow to be successful. Results about the structure of a successful virtual community and its time evolution are provided to determine the mentioned guidelines. Research limitations/implications – The research is limited to a particular virtual community engaged with the development of the ARM-embedded Linux OSS. Other successful virtual communities can be analysed, and the conclusions could be compared. Anyway, the proposed analysis methodology can be extended to other virtual communities. Originality/value – The paper fulfils the development and features of Internet virtual communities to be successful. Results have important implications over the development of new software business models based on virtual communities and open source software. Contributions about the best organisation of virtual communities leading to a successful development of the underlying project are presented.Ministerio de Educación y Ciencia DPI2007- 60128Junta de Andalucía. Consejería de Innovación, Ciencia y Empresa P07-TIC-0262

An empirical study of the driving forces behind online communities

Purpose – A large variety of online communities have emerged during the last years as a result of the challenges faced by both the business and scientific worlds. This trend has also been promoted by the development of internet and new Web 2.0 technologies. In this context, this paper is focused on the determinants of success of online communities. But, as a difference from other studies, these determinants are analyzed from the social network analysis perspective. Several constructs related to the community organization as a social network are proposed and their interrelations are hypothesized in a general research framework. The obtained results test the proposed model providing the most relevant antecedents of the project success. Design/methodology/approach – A case study based on Linux ports to non-conventional processor and environments is used to test the proposed model. Structural equation modeling analysis is used to validate the structural proposed model. Findings – The main antecedents of online communities’ success, quantifying the strength of the relation through the standardized path coefficients. Research limitations/implications – The research is limited to a particular set of online communities engaged with the development of the non-conventional Linux ports. However, they constitute a representative set of communities in the field of the open source projects (OSS) development, which are typically developed using a community of support. Originality/value – This paper fulfils the main antecedents causing the successful development of Internet virtual communities. Instead of using sources of data coming from users’ surveys, this study employs community interactions as a source of data. Results have important implications over the development of online communities, like software business models based on virtual communities and open source softwareMinisterio de Educación y Ciencia DPI2007-60128Junta de Andalucía. Consejería de Innovación, Ciencia y Empresa P07-TIC-0262

Shock wave study and theoretical modeling of the thermal decomposition of c-C4F8

The thermal dissociation of octafluorocyclobutane, c-C4F8, was studied in shock waves over the range 1150-2300 K by recording UV absorption signals of CF2. It was found that the primary reaction nearly exclusively produces 2 C2F4 which afterwards decomposes to 4 CF2. A primary reaction leading to CF2 + C3F6 is not detected (an upper limit to the yield of the latter channel was found to be about 10 percent). The temperature range of earlier single pulse shock wave experiments was extended. The reaction was shown to be close to its high pressure limit. Combining high and low temperature results leads to a rate constant for the primary dissociation of k1 = 1015.97 exp(-310.5 kJ mol-1/RT) s-1 in the range 630-1330 K, over which k1 varies over nearly 14 orders of magnitude. Calculations of the energetics of the reaction pathway and the rate constants support the conclusions from the experiments. Also they shed light on the role of the 1,4-biradical CF2CF2CF2CF2 as an intermediate of the reaction.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada