Ru纳米颗粒包覆ITO纳米线热解纤维素性能研究

以阳极氧化铝(AAO)膜为模板,采用真空机械压注法制备铟锡(InSn)合金纳米线(NWs),然后采用“原位放电还原”方法在InSn NWs表面包覆Ru颗粒。随后,将复合材料在空气中进行热处理,合成RuO₂/ITO NWs。最后,在H₂气氛下还原RuO₂/ITO NWs获得Ru/ITO NWs。结果表明,InSn纳米线直径约为40 nm,2 ~ 5 nm的Ru纳米颗粒均匀地包覆在ITO NWs的表面。此外,检测了所得Ru/ITO NWs对纤维素的催化热解性能,所得产物为1,6-脱水吡喃葡萄糖、乙醇醛和羟基丙酮,对比无催化剂、ITO NWs,Ru/ITO NWs所得产物,可以发现Ru/ITO NWs催化剂减少了1,6-脱水吡喃葡萄糖的产生,表明Ru纳米颗粒加剧了热解过程中的氧桥的断裂,加速生成乙醇醛和羟基丙酮,提高纤维素热解效率。同时对存在醚键的壬基酚聚氧乙烯醚也进行了热解分析,结果表明Ru/ITO NWs对醚键的断裂起明显的催化作用。     

Comparing the quality of life of cities that gained and lost population: An assessment with DEA and the Malmquist index

This study compares the quality of life (QoL) of cities that lost population with that of cities that gained population. A unique dataset composed of observations for 11 dimensions of QoL for all mainland Portuguese cities is used. By employing a non-parametric approach (data envelopment analysis), and by using a Malmquist-type index, this study identifies differences in QoL between the group of cities that lost population and the group of cities that gained population, as well as differences within each group. Despite the heterogeneity in cities that shrunk, this group presents, on average, higher QoL than cities that have grown.     

Influence of processing conditions on the morphological and mechanical properties of compatibilized PP/LCP blends

The main aim of this work is to study the influence of the application of different processing conditions on the morphological and mechanical properties of thermoplastic/LCP blends, in which the viscosity ratios are inferior to unity and decrease with increasing temperature. The way the microstructure evolves along the extruder determines the final morphology and thus, the mechanical performance of the systems. In the present case, the mechanical properties are related with the degree of fibrillation in the final composites. The best degree of fibrillation was obtained for low screw speeds and temperatures and for intermediate outputs. The use of high screw speeds and processing temperatures results in a decrease of the viscosity ratio, in the former case via an increase in the viscous dissipation, at the regions of higher shear rates (kneading‐elements). The application of a lower processing temperature is advantageous for deformation, break‐up, and fibrillar formation because of the higher viscosity ratios and higher shear stresses involved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Riparian vegetation restoration: Does social perception reflect ecological value?

Social‐ecological contexts are key to the success of ecological restoration projects. The ecological quality of restoration efforts, however, may not be fully evident to stakeholders, particularly if the desired aesthetic experience is not delivered. Aesthetically pleasing landscapes are more highly appreciated and tend to be better protected than less appealing landscapes, regardless of their ecological value. Positive public perception of restoration actions may therefore facilitate stakeholder involvement and catalyse recognition of ecological improvement. Here we aim to contrast aesthetical perception and ecological condition in headwater river reaches restored through passive ecological restoration in study areas in Portugal (Alentejo) and France (Normandy). We recorded structural and functional indicators of riparian vegetation to monitor the ecological condition of study sites along a passive restoration trajectory. Aesthetical perception indicators were assessed through stakeholder inquiries developed under a semantic differential approach. We analysed perception responses to changes in the riparian ecosystems resulting from passive ecological restoration across different geographical contexts and social groups. The analysed social groups comprised stakeholders (environmental managers and landowners) and university students (landscape architecture and geography students). Results indicate that (a) visual preferences often do not reflect changes in ecological condition, (b) perception of the restoration process is strongly context dependent, and (c) experience and cultural background affect perception of ecological condition across the different social groups analysed. Clear identification of relevant stakeholder groups (those interested in or directly affected by restoration), effective communication, and stakeholder engagement are therefore essential for assuring the success of river restoration projects.     

Optical fibre-based micro-analyser for indirect measurements of volatile amines levels in fish

An analytical method based on optical fibre (OF) detection has been developed and validated for monitoring of trimethylamine (TMA) and dimethylamine (DMA) in fish handling environments and for non invasive assessment of fish quality.     

Spatial modelling of freshwater fish in semi‐arid river systems: a tool for conservation

This paper examines the feasibility of using multivariate statistics to model fish species distribution and habitat requirements for intermittent streams in semi‐arid regions, many of which are coming under increasing pressure from water resource development schemes. The assessment was based on the geographical distribution of six endemic fish species in the Guadiana river, a semi‐arid river system in southern Iberia. Their presence was related to 20 environmental variables linked to climate, geomorphology, riparian vegetation and location in the drainage basin. These variables were collected in the field or from topographical maps to evaluate habitat suitability and to predict the presence of the species according to season. Multivariate logistic regression in a geographic information system (GIS) environment was performed to identify regions with high probability of occurrence for each species. The variables that best explained the occurrence of the species were the sample location in the drainage basin, the geomorphology and the riparian vegetation. The models presented have a high predictive power and can be used in monitoring and predicting temporal changes caused by human activities. This modelling approach can be used to predict the areas that need to be conserved to protect or rehabilitate the endangered species. Armed with this information, managers can formulate conservation measures to prevent further degradation of the stocks and possibly enhance the populations. Copyright © 2002 John Wiley & Sons, Ltd.     

Defeating Colluding Nodes in Desktop Grid Computing Platforms

Desktop Grid systems reached a preeminent place among the most powerful computing platforms in the planet. Unfortunately, they are extremely vulnerable to mischief, because computing projects exert no administrative or technical control on volunteers. These can very easily output bad results, due to software or hardware glitches (resulting from over-clocking for instance), to get unfair computational credit, or simply to ruin the project. To mitigate this problem, Desktop Grid servers replicate work units and apply majority voting, typically on 2 or 3 results. In this paper, we observe that simple majority voting is powerless against malicious volunteers that collude to attack the project. We argue that to identify this type of attack and to spot colluding nodes, each work unit needs at least 3 voters. In addition, we propose to post-process the voting pools in two steps. i) In the first step, we use a statistical approach to identify nodes that were not colluding, but submitted bad results; ii) then, we use a rather simple principle to go after malicious nodes which acted together: they might have won conflicting voting pools against nodes that were not identified in step i. We use simulation to show that our heuristic can be quite effective against colluding nodes, in scenarios where honest nodes form a majority.     

A real-time photoluminescence imaging system

We have developed a real-time photoluminescence imaging system. In contrast to scanning systems, in our set-up the photoluminescence is excited over theentire area of a sample at once. The intensity of the spectrally resolved emission from the whole sample is monitored and displayed in real-time, in a color-coded format. This system can be used for the quick inspection of optical and electro-optical materials, and is promising for in-situ characterization. As an example for the performance of the system we show data obtained on a GaAs/AlGaAs p-i-n quantum well modulator, and on an InP substrate.