A planar micro-concentrator/injector for low power consumption microchromatographic analysis of benzene and 1,3 butadiene

In the present study, we present the first steps of the development of a low power consumption GC microsystem for the analysis of benzene in the presence of butadiene, involved in petrochemical industrial applications. This system is made by coupling a low power consumption planar microhotplate based on a preconcentrator with good preconcentration capability and a spiral microchromatographic column that presents a separation capability of both compounds at room temperature, when tested in front of a gas sensor. The first characterization results of the device showed a successful injection of benzene and butadiene when placed in front of the micro-separation module.     

Design für Kostentransparenz in Anlageberatungsgespr?chen

Investment advisory services of financial service providers (FSPs) exhibit several characteristics that are detrimental to advisory quality. The interaction of advisor and client is strained by a lack of transparency regarding the advisory process (what activities are performed and why) and the information used therein (what information is used for what purpose and with what effect), as well as regarding the precise costs of the service and the recommended products. In prior research, we suggested that process and information transparency issues may be appropriately addressed with collaborative information technology (IT) artifacts. In this paper, we argue that collaborative, transparent artifacts may also be a premise of enabling cost transparency. To this end, we describe a complete research cycle of designing, implementing, and evaluating a shared cost-transparent IT artifact to support client-advisor interaction in investment advisory encounters. Evaluation results suggest the efficacy of our design in improving the clients?? perceived cost transparency as well as increase their satisfaction and their willingness to pay for the received investment advice. These findings may also challenge the common belief of FSPs that transparent, fee-based advisory services would neither be accepted by clients nor be economically viable. Practical implications of these findings for designing advisory encounters with supportive IT are discussed.     

电力系统低频振荡和储能系统

研究了将能量储存系统用于提高电力系统振荡稳定性的潜力。首先简要回顾了过去40年中在电力系统振荡稳定性领域的研究和应用的发展情况,包括电力系统振荡稳定性的分析和控制;然后论述了在电力系统中应用能量储存系统的不同课题;第3部分重点讨论了用能量储存系统改善电力系统振荡稳定性问题;最后提出了一些建议。     

Localization-limited exciton oscillator strength in colloidal CdSe nanoplatelets revealed by the optically induced stark effect

2D materials are considered for applications that require strong light-matter interaction because of the apparently giant oscillator strength of the exciton tra...     

Energy Efficient Cloud Service Provisioning: Keeping Data Center Granularity in Perspective

The cost of power and its associated delivery are becoming significant factors in the total expenditure of large-scale data centers. Numerous techniques have been proposed to address the energy efficiency issue in cloud systems. Recently, some efforts have been made to decentralize the cloud via distributing data centers in diverse geographical positions, at different scales. In this paper, we elaborate on the energy effectiveness of service provisioning on different cloud architectures, from a mega-data center to a nano data center, which provides the extreme decentralization in terms of cloud architecture, as well as P2P-clouds or community network clouds. We study the energy consumption through an analytical and simulation framework for video streaming and MapReduce applications.     

Self-foaming diphenolic acid benzoxazine

This work concerns the investigation of porous polybenzoxazines based on the non-toxic renewable diphenolic acid. The approach described relies on the in situ generation of foaming agent (CO₂) during the thermal curing. For this purpose, the previously synthesized benzoxazine monomer from diphenolic acid was thermally polymerized at different temperatures. As the beginning of decarboxylation is about 200 °C, we selected five foaming temperatures (T_f) ranging from 190 to 230 °C. The influence of the foaming temperature on the cellular structure and its dependency on final properties is discussed.     

Electrode surface treatments in sludge electro-osmosis dewatering

The sewage sludge dewatering produced by wastewater treatment plants (WWTP) is a multifaceted process due to the presence of colloid fractions. Electro-osmosis could be a suitable technique to reduce the water content of the final sludge. Electric fields of 10, 15, and 20?V/cm have been studied for electro-osmosis tests under the pressure of a static or rotating piston, obtaining a dry solids content up to 40–45%, with respect to 25–30% obtained by mechanical methods. In order to optimize the process, the corrosion behavior and the wear of the anodic material appear to be the main critical aspects, due to the high circulating current density and the use of a rotating electrode. We compared the efficiency and the corrosion resistance of dimensionally stable anodes (DSA) with respect to bare stainless steel (AISI 304) and stainless steel coated by PVD technique with TiN, AlTiN, and DLC. Characterization of the anode surfaces by SEM and potentiodynamic tests show that DSA is the most suitable material for our application. However, efficiencies of the electro-osmosis processes have been found comparable, in terms of developed current densities and total energy consumptions, for short-test duration.     

Structural,optical and electrical properties of silicon nanocrystals embedded in SixC1−x/SiC multilayer systems for photovoltaic applications

In this work we present a structural, optical and electrical characterization of Si_xC_1?x/SiC multilayer systems with different silicon content. After the deposition process, an annealing treatment was carried out in order to induce the silicon nanocrystals formation. By means of energy-filtered transmission electron microscopy (EFTEM) we observed the structural morphology of the multilayers and the presence of crystallized silicon nanoprecipitates for samples annealed up to 1100 °C. We discuss the suitability of optical techniques such as Raman scattering and reflectance and transmittance (R&T) for the evaluation of the crystalline fraction of our samples at different silicon excess ranges. In addition, the combination of R&T measurements with simulation has proved to be a useful instrument to confirm the structural properties observed by EFTEM. Finally, we explore the origin of the extremely high current density revealed by electrical measurements, probably due to the presence of an undesired defective SiC_yO_z ternary compound layer, already supported by the structural and optical results. Nevertheless, the variation of the electrical measurements with the silicon amount indicates a small but significant contribution from the multilayers.     

Three problems with the connectivist conception of learning

Connectivism, which has been argued to be a new learning theory, has emerged in the field of online learning during the last decade. On the World Wide Web at least, connectivism promises to establish learning spaces similar to those that Ivan Illich imagined in ‘Deschooling Society’, through so‐called massive online open courses (MOOCs). In this paper, we critically examine the theoretical postulates of connectivism and identify three important psychological and epistemological problems, namely the lack of a solution to the learning paradox, the underconceptualization of interaction and the inability to explain concept development. Some of the theoretical deficiencies in question may explain certain learning problems experienced by participants in MOOCs. The paper concludes that, although MOOCs are a worthwhile experience and ought to be continued, connectivism as a learning theory has significant theoretical problems and should be profoundly revised if it is to explain and foster learning in such environments.     

Asymmetric Intermolecular Mizoroki-Heck Reaction: From Phosphine/Phosphinite-Nitrogen to Phosphite-Nitrogen Ligands

This review discusses the latest developments in ligand design for the Pd-catalyzed asymmetric intermolecular Mizoroki-Heck reaction, from the successful phosphine/phosphinite-nitrogen ligands to the recently reported phosphite-nitrogen ligands. The presence of a biaryl phosphite group offers several advantages as a ligand scaffold for this process.