Francisco J. Suárez

Highly Efficient Redox Isomerisation of Allylic Alcohols Catalysed by Pyrazole‐Based Ruthenium(IV) Complexes in Water: Mechanisms of Bifunctional Catalysis in Water

The catalytic activity of ruthenium(IV) ([Ru(η(3):η(3)-C(10)H(16))Cl(2)L]; C(10)H(16) = 2,7-dimethylocta-2,6-diene-1,8-diyl, L = pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 3-methyl-5-phenylpyrazole, 2-(1H-pyrazol-3-yl)phenol or indazole) and ruthenium(II) complexes ([Ru(η(6)-arene)Cl(2)(3,5-dimethylpyrazole)]; arene = C(6)H(6), p-cymene or C(6)Me(6)) in the redox isomerisation of allylic alcohols into carbonyl compounds in water is reported. The former show much higher catalytic activity than ruthenium(II) complexes. In particular, a variety of allylic alcohols have been quantitatively isomerised by using [Ru(η(3):η(3)-C(10)H(16))Cl(2)(pyrazole)] as a catalyst; the reactions proceeded faster in water than in THF, and in the absence of base. The isomerisations of monosubstituted alcohols take place rapidly (10-60 min, turn-over frequency = 750-3000 h(-1)) and, in some cases, at 35 °C in 60 min. The nature of the aqueous species formed in water by this complex has been analysed by ESI-MS. To analyse how an aqueous medium can influence the mechanism of the bifunctional catalytic process, DFT calculations (B3LYP) including one or two explicit water molecules and using the polarisable continuum model have been carried out and provide a valuable insight into the role of water on the activity of the bifunctional catalyst. Several mechanisms have been considered and imply the formation of aqua complexes and their deprotonated species generated from [Ru(η(3):η(3)-C(10)H(16))Cl(2)(pyrazole)]. Different competitive pathways based on outer-sphere mechanisms, which imply hydrogen-transfer processes, have been analysed. The overall isomerisation implies two hydrogen-transfer steps from the substrate to the catalyst and subsequent transfer back to the substrate. In addition to the conventional Noyori outer-sphere mechanism, which involves the pyrazolide ligand, a new mechanism with a hydroxopyrazole complex as the active species can be at work in water. The possibility of formation of an enol, which isomerises easily to the keto form in water, also contributes to the efficiency in water.

Synthesis and structure of ruthenium(IV) complexes featuring N-heterocyclic ligands with an N-H group as the hydrogen-bond donor: hydrogen interactions in solution and in the solid state.

The synthesis and characterization of novel ruthenium(IV) complexes [Ru(η(3):η(3)-C(10)H(16))Cl(2)L] [L = 3-methylpyrazole (2b), 3,5-dimethylpyrazole (2c), 3-methyl-5-phenylpyrazole (2d), 2-(1H-pyrazol-5-yl)phenol (2e), 6-azauracile (3), and 1H-indazol-3-ol (4)] are reported. Complex 2e is converted to the chelated complex [Ru(η(3):η(3)-C(10)H(16))Cl(κ(2)-N,O-2-(1H-pyrazol-3-yl)phenoxy)] (5) by treatment with an excess of NaOH. All of the ligands feature N-H, O-H, or C═O as the potential hydrogen-bonding group. The structures of complexes 2a-2c, 2e, 3, and 5 in the solid state have been determined by X-ray diffraction. Complexes 2a-2c and 3, which contain the pyrazole N-H group, exhibit intra- and intermolecular hydrogen bonds with chloride ligands [N-H···Cl distances (Å): intramolecular, 2.30-2.78; intermolecular, 2.59-2.77]. Complexes 2e and 3 bearing respectively O-H and C═O groups also feature N-H···O interactions [intramolecular (2e), 2.27 Å; intermolecular (3), 2.00 Å]. Chelated complex 5, lacking the O-H group, only shows an intramolecular N-H···Cl hydrogen bonding of 2.42 Å. The structure of complex 3, which turns out to be a dimer in the solid state through a double intermolecular N-H···O hydrogen bonding, has also been investigated in solution (CD(2)Cl(2)) by NMR diffusion studies. Diffusion-ordered spectroscopy experiments reveal an equilibrium between monomer and dimer species in solution whose extension depends on the temperature, concentration, and coordinating properties of the solvent. Preliminary catalytic studies show that complex 3 is highly active in the redox isomerization of the allylic alcohols in an aqueous medium under very mild reaction conditions (35 °C) and in the absence of a base.

An efficient networking technique for synchronous e-learning platforms in corporate environments

A synchronous e-learning platform is an effective way to implement training programs for human resources in large corporations. These organizations are usually dispersed in multiple sites very distant from each other, so transport of multimedia data within an e-learning activity is a true challenge. Usually, multimedia data is delivered using the RTP protocol. In this paper, an optimal transport technique based on a multicast overlay network is proposed. The overlay is made up of multiple servers that operate at the RTP level and combine unicast and multicast transport whenever possible. This technique has proved to be more efficient than a solution based exclusively on unicast delivery.

Autonomic Platform for Synchronous e-Training in Dispersed Organizations

Synchronous e-training of human resources uses conferencing services to support training at the workplace. Multimedia data is interchanged between participants in real-time in a synchronous e-training activity providing an enriched learning experience. Large organizations are usually widely dispersed in several sites, so synchronous e-training activities are especially difficult. Most of the sites constitute multicast islands, as IP multicast is available, so the data transport can use IP multicast within the sites of the organization in order to save bandwidth. In this paper, an autonomic synchronous e-training platform based on standard protocols implementing self-management features such as self-deployment, self-organization and self-healing is proposed. The platform deploys an overlay network composed of Real-time Transport Protocol relays acting as multicast/unicast reflectors. The overlay is automatically reorganized according to the joining and leaving of participants and network failures. The use of standard protocols and a modular design enable the interoperability, extensibility and portability of the platform.

A novel real-time fuzzy-based diagnostic system of roll eccentricity influence in finishing hot strip mills

This paper proposes a method for the diagnosis of roll eccentricity influence on the strip thickness at the exit of a finishing hot strip mill (FHSM). Each exit strip thickness defect is related to one roll of the FHSM, allowing the implementation of an optimal policy for the substitution and maintenance of the rolls, while maintaining the required quality level of the strip. This policy allows the minimization of roll changes and the concentration of several changes at the same time, reducing production costs. Fuzzy logic is used to compare spectra, looking for common patterns, which enables a totally-automated diagnostic system. Likewise, as part of the solution, a novel estimate of roll eccentricity, based on a least-squares algorithm has been developed, which provides higher accuracy than classical algorithms as well as a drastic reduction in the time required to perform eccentricity tests.

E-pSyLon: a synchronous e-learning platform for staff training in large corporations

Synchronous e-learning is becoming increasingly popular as a tool for developing human resource training plans in large corporations. A synchronous e-training platform has been designed and implemented to explore the possibilities of synchronous e-training in a large corporation. The client tool is used by learners and instructors to collaborate in real-time during e-training activities. It is based on standard protocols also used in voice over IP, which makes it inter-operable with other software and hardware devices. The functionalities offered by the client tool have been chosen based on those provided by commercial tools, but focusing on the specific characteristics of users and network conditions of corporate environments. This facilitates highly interactive synchronous e-training activities. Multimedia configuration of activities is flexible, so participants with different network link capabilities can join activities. The e-training platform has been tested in real e-training activities in ArcelorMittal Spain. The opinions of the users reflect an enhanced learning experience when using the client tool.

Assessing the QoE in Video Services Over Lossy Networks

Quality of experience is of critical importance in streaming video services, because the traditional quality of service cannot represent the quality perceived by viewers. This work evaluates several objective quality metrics under realistic bursty packet loss conditions in the network, with the support of a packet loss model. Alignment of reference and streamed video sequences (with different levels of spatial-temporal information) are also explored as a technique to prevent inaccurate computation of objective metrics due to frame loss. Finally, the correlation between subjective and objective metrics for each motion level and the computing time of metrics are analysed. The most suitable objective metrics to characterize the real degradation in the quality perceived by viewers, for both off-line and real-time assessment, are proposed. The integration of motion, busty packet loss, sequence alignment after frame loss and computing time of metrics are the main contributions of this research work.

Evaluation of Video Server Capacity with Regard to Quality of the Service in Interactive News-On-Demand Systems

A key issue in any system for distribution of continuous media-on-demand is the capacity of the system with regard to quality of the service specifications, that is, the number of simultaneous streams the system can provide until degradation of the quality of reproduction and interactivity perceived by the users. This work presents the evaluation of interactive video-on-demand systems, with special attention to limitations caused by the video server. The evaluation is based on a set of metrics designed to determine the number of streams a video server can support under specific requirements of the quality of the service as perceived by the users. To validate the utility of these metrics, a prototype of a news-on-demand service has been built and the load for this kind of systems has been characterised. In addition, a load generator which emulates the concurrent access of several users to the system has been built. The evaluation establishes the relationship between the video server limitations and the quality of the service perceived by the users.

Design Issues in Remote Visualization of Information in Interactive Multimedia E Learning Systems

This work deals with the most relevant aspects of the visualization of information in interactive multimedia e-learning systems and the underlying design and implementation issues for a tool to support the functionality required in these systems properly. This paper is focused on synchronous e-learning systems, but the concepts presented can be applied to many other interactive systems, such as videoconferencing, collaborative work and e-meeting systems. In these systems a slide presentation is visualized by all users, who usually work collaboratively on the presentation integrating digital ink annotations.Although there are several tools that support the visualization and real-time annotation of electronic presentations, most of them have been designed to work in local visualization environments, typically within a classroom, and few details of their design and the technologies used in their implementation have been disclosed. The main contribution of this paper is to go a step beyond local environments, considering the functionality required in remote visualization environments and providing detailed aspects of their design and implementation.

PET, a software monitoring toolkit for performance analysis of parallel embedded applications

Since the late 1980s a great deal of research has been dedicated to the development of software monitoring and visualization toolkits for parallel systems. These toolkits have traditionally been oriented to measuring and analyzing parallel scientific applications. However, nowadays, other types of parallel applications, using signal-processing or image-processing techniques, are becoming increasingly importance in the field of embedded computing. Such applications are executed on special parallel computers, normally known as embedded multiprocessors, and they exhibit structural and behavioral characteristics very different from scientific applications. Because of this, monitoring tools with specific characteristics are required for measuring and analyzing parallel embedded applications.In this paper we present performance execution tracer (PET), a monitoring and visualization toolkit specifically developed to measure and analyze this type of application. Special emphasis is placed on explaining how PET deals with the particular characteristics of these applications. In addition, in order to demonstrate the capabilities of PET, the measurement and analysis of a real application using this tool are described.