29 research outputs found
Service Orientation and the Smart Grid state and trends
The energy market is undergoing major changes, the most notable of which is the transition from a hierarchical closed system toward a more open one highly based on a âsmartâ information-rich infrastructure. This transition calls for new information and communication technologies infrastructures and standards to support it. In this paper, we review the current state of affairs and the actual technologies with respect to such transition. Additionally, we highlight the contact points between the needs of the future grid and the advantages brought by service-oriented architectures.
On the synchronization of IEEE 802.15.5 wireless mesh sensor networks: Shortcomings and improvements
Mesoporous silica nanoparticles with tunable pore size for tailored gold nanoparticles
The aim of this paper was to verify a
possible correlation between the pore-size of meso-
porous silica nanoparticles (MSNs) and the sizes of
gold nanoparticles (AuNPs) obtained by an impreg-
nation of gold(III) chloride hydrate solution in the
MSNs, followed by a specific thermal treatment.
Mesoporous silica nanoparticles with tunable pore
diameter were synthesized via a surfactant-assisted
method. Tetraethoxysilane as silica precursor, cetyl-
trimethylammonium bromide (CTAB) as surfactant
and toluene as swelling agent were used. By varying
the CTABâtoluene molar ratio, the average dimension
of the pores could be tuned from 2.8 to 5.5 nm.
Successively, thiol groups were grafted on the surface
of the MSNs. Finally, the thermal evolution of the gold
salt, followed by ââin situââ X-ray powder diffraction
(XRPD) and thermogravimetric analysis (TGA),
revealed an evident correlation among the degradation
of the thiol groups, the pore dimension of the MSNs
and the size of the AuNPs. The samples were
characterized by means of nitrogen adsorptionâ
desorption, transmission electron microscopy, small-
angle X-ray scattering, XRPD ââin situââ by synchro-
tron radiation, and ââex situââ by conventional tech-
niques, diffuse reflectance infrared Fourier transform
spectroscopy, and TGA
BANKING REFORM IN ASIA: A PROGRESS REPORT
This article surveys and quantifies the progress made by five Asian economies during the period 1997-1999 in the reform and restructuring of their banking systems, paying particular attention to the very different circumstances and policy solutions in each of them. It develops a simple and objective scoring system of the progress achieved-one that puts South Korea at the top, Japan and Malaysia in the middle, and Thailand and Indonesia at the bottom. The relative success achieved in South Korea and Malaysia is attributed in part to their establishment of "Asset Management Corporations," bodies charged with buying non-performing loans, managing (and in some cases restructuring) the assets underlying the loans, and eventually reselling the loans. This practice has allowed for a more direct approach to corporate restructuring. 1999 Morgan Stanley.
Evolution of the Nonionic Inverse Microemulsion-Acid-TEOS System during the Synthesis of Nanosized Silica via the Sol-Gel Process
The cyclohexane-igepal inverse microemulsion, comprehensively established for the synthesis of silica nanoparticles
in an ammonia-catalyzed sol-gel process, was alternatively studied with an acid-catalyzed sol-gel process. Tetraethyl
orthosilicate (TEOS) was used as the silica precursor, while two different aqueous phases containing either HNO3 or
HCl at two different concentrations, 0.1 and 0.05 M, were examined in the presence and in the absence of NaF, a catalyst
of the condensation step. The evolution of the overall reacting system, specifically hydrolysis and polycondensation of
reaction intermediates, was monitored in situ by time-resolved small-angle X-ray scattering. No size variation of the
inverse micelles was detected throughout the sol-gel process. Conversely, the density of the micellar core increased after
a certain time interval, indicating the presence of the polycondensation product. The IR spectra of the reacting mixture
were in agreement with such a hypothesis. 1Hand 13CNMRmeasurements provided information on the soluble species,
the surfactant, and TEOS. The TEOS consumption was well fitted by means of an exponential decay, suggesting that
a first-order kinetics for TEOS transpires in the various systems examined, with rate constants dependent not only on the
acid concentration but also on its nature (anion specific effect), on the presence of NaF, and on the amount of water in
the core of the inverse micelle. The self-diffusion coefficients, determined by means of PGSTE NMR, proved that
a sizable amount of the byproduct ethanol was partitioned inside the inverse micelles. Characterization of the final
product was carried out by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and
transmission electron microscopy (TEM), which concurrently confirmed that the silica isolated from the inverse
nonionic microemulsion is not significantly different from the product of a bulk acid-catalyzed sol-gel synthesis. TEM
micrographs illustrated particles with diameters smaller than the diameter of the inverse micelles as determined by
SAXS, due to a shrinkage effect, in addition to nanostructured aggregates in the range 20-100 nm
Synthesis and optical properties of sub-micron sized rare earth-doped zirconia particles
Sub-micron sized crystalline particles of Eu3+ and Er3+-doped zirconia (ZrO2) were prepared via a wet chemical solâgel route and post synthesis annealing. The doping was achieved by introduction of the respective rare earth salts into the zirconia precursor solution, with insitu generation of sodium chloride for stabilization of the particle surface during growth. A series of materials with differing europium content, nominally 0.3, 3 and 6 mol% within the ZrO2 lattice, were prepared for respective comparison and characterization of their optical properties following annealing at 700 °C. Average emission lifetimes of up to 2.3 ms were observed for the Eu3+-doped particles. Particle sizes, approximated from SEM micrographs, were observed in the range 250â400 nm. The synthesis of Er3+-doped ZrO2 particles (0.5 mol%) produced 300 nm sized particles which exhibited emission in the visible and infrared regions after annealing at 1000 °C. X-ray diffraction (XRD) with Rietveld analysis for phase quantification, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectra were used to characterize the samples
Evolution of the Nonionic Inverse MicroemulsionâAcidâTEOS System during the Synthesis of Nanosized Silica via the SolâGel Process
The cyclohexaneâigepal inverse microemulsion, comprehensively established for the synthesis of silica nanoparticles in an ammonia-catalyzed solâgel process, was alternatively studied with an acid-catalyzed solâgel process. Tetraethyl orthosilicate (TEOS) was used as the silica precursor, while two different aqueous phases containing either HNO3 or HCl at two different concentrations, 0.1 and 0.05 M, were examined in the presence and in the absence of NaF, a catalyst of the condensation step. The evolution of the overall reacting system, specifically hydrolysis and polycondensation of reaction intermediates, was monitored in situ by time-resolved small-angle X-ray scattering. No size variation of the inverse micelles was detected throughout the solâgel process. Conversely, the density of the micellar core increased after a certain time interval, indicating the presence of the polycondensation product. The IR spectra of the reacting mixture were in agreement with such a hypothesis. 1H and 13C NMR measurements provided information on the soluble species, the surfactant, and TEOS. The TEOS consumption was well fitted by means of an exponential decay, suggesting that a first-order kinetics for TEOS transpires in the various systems examined, with rate constants dependent not only on the acid concentration but also on its nature (anion specific effect), on the presence of NaF, and on the amount of water in the core of the inverse micelle. The self-diffusion coefficients, determined by means of PGSTE NMR, proved that a sizable amount of the byproduct ethanol was partitioned inside the inverse micelles. Characterization of the final product was carried out by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM), which concurrently confirmed that the silica isolated from the inverse nonionic microemulsion is not significantly different from the product of a bulk acid-catalyzed solâgel synthesis. TEM micrographs illustrated particles with diameters smaller than the diameter of the inverse micelles as determined by SAXS, due to a shrinkage effect, in addition to nanostructured aggregates in the range 20â100 nm
Structural and photoluminescence properties of ZrO2:Eu3+ @ SiO2 nanophosphors as a function of annealing temperature
The synthesis, morphology and luminescence properties of two systems comprising luminescent Eu3+-doped zirconium oxide nanocrystals embedded in an amorphous silica matrix are reported. The two systems, prepared with the same overall wt% composition of silica (75%) and EuxZr(1âx)O(2âx/2) solid solution (25%), have been annealed in the range 135â1000 °C and subsequently functionalized with (3-aminopropyl)triethoxysilane. Detailed X-ray diffraction analyses and transmission electron micrographs, combined with infrared spectroscopy and luminescence spectroscopy data, have been used to demonstrate the influence of annealing temperature on the: (i) nanostructure, (ii) luminescence properties and (iii) availability of superficial âOH groups for efficient surface functionalization. The optimum calcination temperature was found to be 700 °C for each series in terms of luminescence lifetime efficiency and post-functionalization efficiency with (3-aminopropyl)triethoxysilane
Structural and luminescence properties of europium(III)-doped zirconium carbonates and silica-supported Eu3+-doped zirconium carbonate nanoparticles
The synthesis, morphology and luminescence properties of europium(III)-doped zirconium carbonates prepared as bulk materials and as silica-supported nanoparticles with differing calcination treatments are reported. Transmission electron microscopy and X-ray diffraction analyses have, respectively, been used to study the morphology and to quantify the atomic amount of europium present in the optically active phases of the variously prepared nanomaterials. Rietveld analysis was used to quantify the constituting phases and to determinate the europium content. Silica particles with an approximate size of 30 nm were coated with 2 nm carbonate nanoparticles, prepared in situ on the surface of the silica core. Luminescence measurements revealed the role of different preparation methods and of europium-doping quantities on the optical properties observed