Synthesis of polar vinyl monomer–olefin copolymers by α‐diimine nickel catalyst

Vinyl acetate, methyl methacrylate, acrylonitrile and methyl vinyl ketone were investigated for co‐ and terpolymerization with ethylene and ethylene–propylene. Precursor [bis(N,N ′‐dimesitylimino)acenaphthene]dibromonickel, activated by methylaluminoxane was used as a catalyst system and trialkylaluminium was employed to block the polar groups for these polymerizations. Polymerization activities of the order of magnitude of 10⁶ in the case of vinyl acetate and methyl methacrylate, and 10⁵ in the case of acrylonitrile were achieved. Microanalysis and GPC of acrylonitrile copolymers found about 17 units of acrylonitrile per polymer chain. Copolymers with very different properties from the parent homopolymers were obtained in all cases except that of methyl vinyl ketone. © 2001 Society of Chemical Industry     

Partial oxidation of methane over bimetallic nickel–lanthanide oxides

The study of partial oxidation of methane (POM) over bimetallic nickel–lanthanide oxides was undertaken. Binary intermetallic compounds of the type LnNi (Ln = Pr, Gd, Lu) were used as bimetallic nickel–lanthanide oxides precursors and the products (NiO·Pr₂NiO₄, 2NiO·Gd₂O₃ and 2NiO·Lu₂O₃) were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, Raman and temperature programmed reduction. The catalytic activity increases when gadolinium or lutetium replaces praseodymium and the selectivity of the bimetallic nickel–lanthanide oxides is clearly different from that of single metal oxides and/or mechanical mixtures.The existence of an unusual synergism effect between the two metal oxide phases (NiO and Ln₂O₃) that lead to higher conversions of methane and higher selectivities to hydrogen and carbon monoxide correlate also the catalysts stability to deactivation. The activity and selectivity of the gadolinium and lutetium compounds is, under the same conditions, equivalent to that of a platinum commercial catalyst, 5 wt% Pt/Al₂O₃, which stresses the good catalytic performance of this new type of compounds for the production of H₂ and CO (H₂/CO = 2).     

Designing a Collaborative Visual Analytics Tool for Social and Technological Change Prediction

This paper discussed about GreenOracle which an interdisciplinary team designed and developed. GreenOracle is a collaborative visual analytics tool for predicting global climate change's impact on US power grids and its implications for society and national security. These future scenarios provide critical assessments and information to help policymakers and stakeholders formulate a coherent and unified strategy toward shaping a safe and secure society.     

Methods for automatic and assisted image annotation

Personal memories composed of digital pictures are very popular at the moment. To retrieve these media items annotation is required. During the last years, several approaches have been proposed in order to overcome the image annotation problem. This paper presents our proposals to address this problem. Automatic and semi-automatic learning methods for semantic concepts are presented. The automatic method is based on semantic concepts estimated using visual content, context metadata and audio information. The semi-automatic method is based on results provided by a computer game. The paper describes our proposals and presents their evaluations.     

Low complexity Byzantine-resilient consensus

The application of the tolerance paradigm to security - intrusion tolerance - has been raising a reasonable amount of attention in the dependability and security communities. In this paper we present a novel approach to intrusion tolerance. The idea is to use privileged components - generically designated by wormholes - to support the execution of intrusion-tolerant protocols, often called Byzantine-resilient in the literature.The paper introduces the design of wormhole-aware intrusion-tolerant protocols using a classical distributed systems problem: consensus. The system where the consensus protocol runs is mostly asynchronous and can fail in an arbitrary way, except for the wormhole, which is secure and synchronous. Using the wormhole to execute a few critical steps, the protocol manages to have a low time complexity: in the best case, it runs in two rounds, even if some processes are malicious. The protocol also shows how often theoretical partial synchrony assumptions can be substantiated in practical distributed systems. The paper shows the significance of the TTCB as an engineering paradigm, since the protocol manages to be simple when compared with other protocols in the literature.Published online: 29 October 2004This work was partially supported by the EC, through project IST-1999-11583 (MAFTIA), and by the FCT, through the Large-Scale Informatic Systems Laboratory (LASIGE) and projects POSI/1999/CHS/33996 (DEFEATS) and POSI/CHS/39815/2001 (COPE).     

Effects of sediment geochemical properties on the toxicity of copper-spiked sediments to the marine amphipod Gammarus locusta

The contribution of some sediment features, namely acid-volatile sulfide (AVS) and total organic carbon (TOC) in order to explain the toxicity of copper-spiked sediments was investigated. A 10-day assay with the marine amphipod Gammarus locusta was performed with three selected sediment types that consisted of different proportions of fine fractions (FF) and TOC (0.5% FF/1% TOC; 25% FF/2% TOC; and 75% FF/4% TOC). Copper toxic effects were observed for 0.5% FF/25% FF sediments when simultaneously extracted copper (SEM(Cu)) minus acid volatile sulfide (SEM(Cu) - AVS) were 0.3 and 3.4 micromol/g, respectively. However, no significant mortality was observed for 75% FF sediment even when the sulfide binding capacity was exceeded (1.1 micromol/g < or = SEM(Cu) - AVS < or = 8.9 micromol/g). These results indicate that mortality could not be described solely as a function of the SEM(Cu) - AVS, suggesting the presence of other binding phases in addition to AVS. Results of the normalized LC50 values to total organic carbon indicated that this component probably also interferes in the amphipod survival, although not completely. The estimated LC50 values were close (2 mg Cu/g C and 8 mg Cu/g C, respectively for 0% FF and 25% FF sediment) although there was still a fourfold difference between them. Considering that none of these sediment features by itself could fully explain copper toxicity, an attempt was made to describe G. locusta mortality as a function of simultaneous SEM(Cu) - AVS and copper concentrations normalized to TOC. Nevertheless, the limited set of data available from this study prevented an attempt to model toxicity as a function of both of these factors. These findings reinforce the need to develop integrated models that include more than one binding phase, sulfide and organic carbon, and also other compartments of the system (e.g. interstitial water) to improve current methodologies for predicting copper toxicity based on sediment geochemical features.     

Viscosity Measurements of Liquid Toluene at Low Temperatures Using a Dual Vibrating-Wire Technique

A recently developed dual vibrating-wire technique has been used to perform viscosity measurements of liquid toluene in the temperature range 213 KT298 K, and at pressures up to approximately 20 MPa. The results were obtained by operating the vibrating-wire sensor in both forced and free decay modes. The estimated precision of the viscosity measurements, in either mode of operation, is ±0.5%, for temperatures above or equal to 273 K, increasing with decreasing temperature up to ±1% at 213 K. The corresponding overall uncertainty is estimated to be within ±1% and ±1.5%, respectively.     

Influence of corona on the voltages induced by nearby lightning onoverhead distribution lines

A model for the calculation of lightning-induced voltages is presented with the aim of assessing the effect of corona when power distribution lines are illuminated by lightning electromagnetic fields. Corona is taken into account by means of dynamic capacitance describing a charge-voltage diagram. Such an equivalent capacitance is then introduced in a model which describes a line illuminated by a lightning electromagnetic field. It is first concluded that the influence of corona on lightning induced overvoltages is of importance only for particularly severe strokes. It is also found that corona acts to increase the magnitude of these overvoltages, contrary to the case of voltages due to direct strokes, which are attenuated by corona. A theoretical explanation of such an amplitude increase is presented. The effect of the ground resistivity is also taken into account in the calculations. The results show that such an effect is in general as important as the effect of corona. This is different from the direct-strike behavior, where corona, when present, affects the surge propagation more than the ground resistivity. This is due to the fact that for the case of induced-voltages, the ground resistivity may affect more strongly the lightning-radiated fields rather than the surge propagation along the line, while corona affects only surge propagation. The need for experimental results to test the theoretical finding of the paper is stressed and some indication is given. Finally, a sensitivity analysis of the induced voltages as a function of the charge-voltage diagram adopted to model corona is also performed     

Extension of the simulated drinking game procedure to multiple drinking games.

The present study extended the Simulated Drinking Game Procedure (SDGP) to obtain information about different types of drinking games. Phase I participants (N = 545) completed online screening questionnaires assessing substance use and drinking game participation. Participants who met the selection criteria for Phase II (N = 92) participated in laboratory sessions that consisted of three different periods of drinking game play. Sixty-two percent (N = 57) of the sample was female. Data from these sessions was used to estimate the peak Blood Alcohol Concentration (BAC) a participant would achieve if they consumed alcohol while participating in the SDGP. Total consumption and estimated BAC varied as a function of game type. The total consumption and estimated BAC obtained while playing Beer Pong and Memory varied significantly as a function of group. Total ounces consumed while playing Three Man varied significantly as a function of group; however, the variation in estimated BAC obtained while playing Three Man was not significant. Results indicated that estimated BACs were higher for female participants across game type. Previous experience playing the three drinking games had no impact on total drink consumption or estimated BAC obtained while participating in the SDGP. The present study demonstrated that the SDGP can be used to generate estimates of how much alcohol is consumed and the associated obtained BAC during multiple types of drinking games. In order to fully examine whether previous experience factors in to overall alcohol consumption and BAC, future research should extend the SDGP to incorporate laboratory administration of alcohol during drinking game participation. (PsycINFO Database Record (c) 2011 APA, all rights reserved)