Highly Emitting Neutral Dinuclear Rhenium Complexes as Phosphorescent Dopants for Electroluminescent Devices

A series of neutral, dinuclear, luminescent rhenium(I) complexes suitable for phosphorescent organic light emitting devices (OLEDs) is reported. These compounds, of general formula [Re₂(µ‐Cl)₂(CO)₆(µ‐1,2‐diazine)], contain diazines bearing alkyl groups in one or in both the β positions. Their electrochemical and photophysical properties are presented, as well as a combined density functional and time‐dependent density functional study of their geometry, relative stability and electronic structure. The complexes show intense green/yellow emissions in toluene solution and in the solid state and some of the complexes possess high emission quantum yields (? = 0.18–0.22 for the derivatives with disubstituted diazines). In butyronitrile glass, at 77 K, due to the charge transfer character of the lowest (emitting) excited state, strong blue shift of the emission is observed, accompanied by a strong increase in the lifetime values. The highest‐performing emitting complex, containing cyclopentapyridazine as ligand, is tested in a polymer‐based light‐emitting device, with poly(9‐vinylcarbazole) as matrix, as well as in a device obtained by vacuum sublimation of the complex in the 2,7‐bis(diphenylphosphine oxide)‐9‐(9‐phenylcarbazol‐3‐yl)‐9‐phenylfluorene (PCF) matrix. This represents the first example of devices obtained with a rhenium complex which can be sublimed and is solution processable. Furthermore, the emission is the bluest ever reported for electrogenerated luminescence for rhenium complexes.     

MR imaging and osteoporosis: fractal lacunarity analysis of trabecular bone.

We develop a method of magnetic resonance (MR) image analysis able to provide parameter(s) sensitive to bone microarchitecture changes in aging, and to osteoporosis onset and progression. The method has been built taking into account fractal properties of many anatomic and physiologic structures. Fractal lacunarity analysis has been used to determine relevant parameter(s) to differentiate among three types of trabecular bone structure (healthy young, healthy perimenopausal, and osteoporotic patients) from lumbar vertebra MR images. In particular, we propose to approximate the lacunarity function by a hyperbola model function that depends on three coefficients, alpha, beta, and gamma, and to compute these coefficients as the solution of a least squares problem. This triplet of coefficients provides a model function that better represents the variation of mass density of pixels in the image considered. Clinical application of this preliminary version of our method suggests that one of the three coefficients, beta, may represent a standard for the evaluation of trabecular bone architecture and a potentially useful parametric index for the early diagnosis of osteoporosis.     

Hybrid GA and OPF evaluation of network capacity for distributed generation connections

Many methods have been applied to examine the capacity of existing distribution networks to accept distributed generation (DG). One aspect missing from existing approaches is the capability to efficiently site and size a predefined number of DGs. Here, a hybrid method employing genetic algorithms and optimal power flow aims to overcome this shortcoming. It could be applied by distribution network operators to search a network for the best sites and capacities available to strategically connect a defined number of DGs among a large number of potential combinations. Some applications of the proposed methodology in the UK under current Ofgem financial incentives for DNOs confirmed its effectiveness in siting and sizing an assigned number of DG units.     

Characterization of low-density polybutadiene latexes by sedimentation field–flow fractionation

A procedure based on sedimentation field–flow fractionation for physical characterization of polydisperse latexes is presented. The particle density, dimensions, polydispersity, size distribution and aggregation can be determined for both narrow and wide polydispersities. The procedure is applied to the sample case of polybutadiene latexes with density lower than water. The results are compared with independent measurements obtained by electron microscopy. The relevance of significant steps of the procedure, such as the nonequilibrium corrections, are discussed.     

MAPON: Master Antenna Passive Optical Network for the Distribution of Digital Video Broadband Services in the European ACTS-CRABS Project

The European ACTS-CRABS project addresses theproblem of delivering broadband and interactivedigital video channels over a wireless 40 GHz fixedpoint-to-multipoint cellular network connectingantennas typically placed on the top of office orapartment buildings. An important issue of thisproject is the final distribution of the signal insidethe building itself. The proposed solution is based ona passive optical network (MAPON) designed to deliverthe signal from a Master Antenna to the final usersapartment. This paper presents an overview of theMAPON solution architecture and hardware, togetherwith the results obtained on an installed testbed. Theissues of low-cost design, system bandwidthlimitations, transmitter clipping and power budget areaddressed, together with the proposed solutions. Weexperimentally measured a power budget that wouldallow the distribution to up to 32 users over lengthsof the order of 150 m.     

High current superconductors for DEMO

In the assumption that DEMO will be an inductively driven tokamak, the number of load cycles will be in the range of several hundred thousands. The requirements for a new generation of Nb₃Sn based high current conductors for DEMO are drafted starting from the output of system code PROCESS. The key objectives include the stability of the DC performance over the lifetime of the machine and the effective use of the Nb₃Sn strand properties, for cost and reliability reasons. A preliminary layout of the winding pack and conductors for the toroidal field magnets is presented. To suppress the mechanism of reversible and irreversible degradation, i.e. to preserve in the cabled conductor the high critical current density of the strand, the thermal strain must be insignificant and no space for micro-bending under transverse load must be left in the strand bundle. The “react-and-wind” method is preferred here, with a graded, layer wound magnet, containing both Nb₃Sn and NbTi layers. The implications of the conductor choice on the coil design and technology are highlighted. A roadmap is sketched for the development of a full size prototype conductor sample and demonstration of the key technologies.     

Direct utilization of methanol in solid oxide fuel cells: An electrochemical and catalytic study

This study deals with an investigation of the direct methanol oxidation in Solid Oxide Fuel Cells (SOFCs). A new catalyst formulation characterized by mixed electronic - ionic conductivity was developed for the anodic process. A composite Ni-modified La_0.6Sr_0.4Fe_0.8Co_0.2O₃-Ce_0.9Gd_0.1O₂ electrocatalyst was prepared by incipient wetness and subsequent ball milling. The obtained composite material was calcined at 1100 °C for 2 h in static air. After thermal activation, Ni was mainly present as highly dispersed La₂NiO₄ particles on a La-depleted Sr(Fe_0.5Co_0.5)O_2.88 perovskite. The subsequent thermal reduction at 800 °C in hydrogen caused the occurrence of highly dispersed metallic Ni on the electrocatalyst surface. The surface area of the composite material was determined by BET measurement. The reduced catalyst was used as anode in intermediate temperature Solid Oxide Fuel Cells (IT-SOFCs) directly fed with methanol. Ex-situ catalytic studies for the composite anode material under steam reforming, partial oxidation and autothermal reforming of methanol were carried out at 800 °C. A comparison of SOFC performance at 800 °C in the presence of syngas or methanol as fuels was carried out. The performance achieved for the direct utilization of methanol (350 mW cm⁻²) appears promising for SOFC application in remote and micro-distributed energy generation as well as for portable power sources.     

A Petri net based protection monitoring system for distribution networks with distributed generation

Connection of distributed generation (DG) essentially changes distribution network operation and creates a range of well-documented effects varying voltage levels and short circuit currents. Among others, DG can alter protection system operations in distribution networks, leading to failure of reclosing, disconnection of healthy feeder or prevention of protection operation. This paper proposes a procedure, based on Petri nets and supported by a centralized monitoring architecture for monitoring failures of the protection systems in radial distribution networks. Some case studies applied to a real Italian distribution network proved the effectiveness of the proposed procedure that can therefore represent an effective solution to improve distribution systems reliability in presence of DG.     

Market research for requirements analysis using linguistic tools

Numerous studies in recent months have proposed the use of linguistic instruments to support requirements analysis. There are two main reasons for this: (i) the progress made in natural language processing and (ii) the need to provide the developers of software systems with support in the early phases of requirements definition and conceptual modelling. This paper presents the results of an online market research intended (a) to assess the economic advantages of developing a CASE (computer-aided software engineering) tool that integrates linguistic analysis techniques for documents written in natural language, and (b) to verify the existence of the potential demand for such a tool. The research included a study of the language – ranging from completely natural to highly restricted – used in documents available for requirements analysis, an important factor given that on a technological level there is a trade-off between the language used and the performance of the linguistic instruments. To determine the potential demand for such tool, some of the survey questions dealt with the adoption of development methodologies and consequently with models and support tools; other questions referred to activities deemed critical by the companies involved. Through statistical correspondence analysis of the responses, we were able to outline two profiles of companies that correspond to two potential market niches, which are characterised by their very different approach to software development.