Life cycle of hydroprocessing catalysts and total catalyst management

Hydroprocessing catalysts based on Ni, Co, Mo and W are used in various refinery processing applications where several deactivation mechanisms become of importance (coke formation, active phase sintering, metals deposition, poisoning) in the catalyst's life cycle. The life cycle of commercial hydroprocessing catalysts is very complex and includes the catalyst production, sulfidation, use, oxidative regeneration followed by re-sulfidation and reuse or, if reuse is not possible, recycling or disposal. To understand the changes in catalyst properties taking place during a life cycle, the catalyst quality in the different stages can be best monitored by using advanced analytical techniques. The catalyst's life cycle is further complicated by numerous technical, environmental and organizational issues involved. In principle, different companies can be involved in each of the life cycle steps. Leading catalyst manufacturers, together with specialized firms, offer refineries a total catalyst management concept, starting with the purchase of the fresh catalyst and ending with its final recycling or disposal. Total catalyst management includes a broad range of services, ensuring optimal timing during the change-out process, reliable, smooth and safe operations, minimal downtime and maximum catalyst and unit performance.     

Test Rig for High-Temperature Thermopower and Electrical Conductivity Measurements

A high-temperature test rig to simultaneously measure electrical conductivity and thermopower is described. The apparatus allows to perform measurements in a controlled atmosphere or vacuum to protect oxygen-sensitive materials. A spring-loaded mounting placed in the cold zone reduces the thermal contact resistance between the sample and two metallic blocks (the hot side and the heat sink) even at high temperatures. The hot-side metal block is periodically heated to obtain the thermopower from the slope of ΔV versus ΔT. Conductivity is measured before each thermopower measurement by a linear four-wire method. The automatic data acquisition and analysis are controlled by a LabView-based interface. Two interchangeable setups are possible. The first one uses silver blocks and K-type thermocouples and is suitable for temperatures from 300 K to about 1000 K. The second one uses W blocks and S-type thermocouples to allow higher-temperature measurements since all the hot-zone parts are made of Al₂O₃, Pt or W. The device was tested using PdAg alloy and Ni rods and, for the low-temperature range, the NIST standard reference material 3451 (bismuth telluride), strictly confirming the reference data.     

A cantilever array-based artificial nose

We present quantitative and qualitative detection of analyte vapors using a microfabricated silicon cantilever array. To observe transduction of physical and chemical processes into nanomechanical motion of the cantilever, swelling of a polymer layer on the cantilever is monitored during exposure to the analyte. This motion is tracked by a beam-deflection technique using a time multiplexing scheme. The response pattern of eight cantilevers is analyzed via principal component analysis (PCA) and artificial neural network (ANN) techniques, which facilitates the application of the device as an artificial chemical nose. Analytes tested comprise chemical solvents, a homologous series of primary alcohols, and natural flavors. First differential measurements of surface stress change due to protein adsorption on a cantilever array are shown using a liquid cell.     

First data from the EGLE experiment onboard the ISS

EGLE is a wide frequency band search- coil magnetometer designed and built at the Roma Tre University. It has been installed onboard the ISS by the Italian astronaut Roberto Vittori on April 25, 2005 within the LAZIO- EGLE experiment carried out during the ENEIDE Soyuz mission. The scope of the experiment is to test EGLE in space and to investigate geomagnetic field variations. The main applications of EGLE are the study of electromagnetic environment inside the ISS, the correlation of magnetic field data with particle fluxes detected by LAZIO particle detector, and the monitoring of ionospheric perturbations possibly caused by Earth seismic activity. Since continuous electromagnetic field measurements on board the ISS are important for diverse space applications, a magnetometer with a suitable design is requested. Appropriate solutions for these applications, which have been adopted by EGLE, are in particular the use of 1- Wire technology and the possibility to detect by means of a search- coil magnetometer a large portion of the ULF frequency band, usually measured by flux- gate probes. To investigate the topside ionosphere electromagnetic environment and stability of Van Allen radiation belts in relation with seismic and anthropogenic electromagnetic emissions, a specific satellite mission (the ESPERIA project) has been designed for the Italian Space Agency (ASI), and up to now a few instruments of its payload have been built and tested in space. One of them is exactly the EGLE search- coil magnetometer. The first magnetic observations performed by this instrument reveal to be promising and demand for a further and deeper analysis based on a longer time series of data.     

ENHANCEMENT OF THE CAPABILITIES OF AN NMR IMAGING MACHINE USING EXPERT SYSTEMS

ABSTRACT

Practical effectiveness of NMR imaging in diagnostic medicine can be considerably upgraded by incorporating into the machine high-level intelligent software support. Partly because NMR imaging is a relatively new technology, knowledge acquisition is essentially related to incoming new experience. Therefore an expert system approach to NMR medical applications should rely on rule induction techniques based on a series of example expert decisions. The complete project consists of three main components: (1) a protocol expert system, (2) a diagnosis expert system, and (3) a vision system. Expert system prototypes regarding part 1 and 2 of this study were built indicating preliminary interesting results. These results justify our attempts aimed at the enhancement of NMR capabilities as a diagnostic tool and consequent commercial benefits.     

A model of a trust-based recommendation system on a social network

In this paper, we present a model of a trust-based recommendation system on a social network. The idea of the model is that agents use their social network to reach information and their trust relationships to filter it. We investigate how the dynamics of trust among agents affect the performance of the system by comparing it to a frequency-based recommendation system. Furthermore, we identify the impact of network density, preference heterogeneity among agents, and knowledge sparseness to be crucial factors for the performance of the system. The system self-organises in a state with performance near to the optimum; the performance on the global level is an emergent property of the system, achieved without explicit coordination from the local interactions of agents.     

Development of a biomimetic chitosan film-coated gold electrode for determination of dopamine in the presence of ascorbic acid and uric acid

A gold electrode surface was modified using a dinuclear copper complex [Cu^II₂ (Ldtb)(μ-OCH₃)](BPh₄) and then coated with a chitosan film. This biomimetic polymer film-coated electrode was employed to eliminate the interference from ascorbic acid and uric acid in the sensitive and selective determination of dopamine. The optimized conditions obtained for the biomimetic electrode were 0.1 M phosphate buffer solution (pH 8.0), complex concentration of 2.0 × 10⁻⁴ M, 0.1% of chitosan and 0.25% of glyoxal. Under the optimum conditions, the calibration curve was linear in the concentration range of 4.99 × 10⁻⁷ to 1.92 × 10⁻⁵ M, and detection and quantification limits were 3.57 × 10⁻⁷ M and 1.07 × 10⁻⁶ M, respectively. The recovery study gave values of 95.2-102.6%. The lifetime of this biomimetic sensor showed apparent loss of activity after 70 determinations. The results obtained with the modified electrode for dopamine quantification in the injection solution matrix were in good agreement with those of the pharmacopoeia method.     

Single wall carbon nanohorns coated with anatase titanium oxide

Single wall carbon nanohorns (SWCNHs) were coated with anatase titanium oxide thin films by metal-organic chemical vapour deposition with titanium tetraisopropoxide Ti(OiPr)₄ as the precursor. The pristine SWCNHs and the new hybrid material SWCNHs/TiO₂ were characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, thermogravimetric thermal analysis and inductively coupled plasma-mass spectrometry, showing that the deposition process does not alter the typical structures of the SWCNHs. Finally, it is shown how the hydrophilic properties of the titanium oxide coating allowed a stable dispersion of SWCNHs/TiO₂ in water, opening new perspectives for water based nanofluids, biological sensing or drug delivery systems.     

The “Roman pot” spectrometer and the vertex detector of experiment UA4 at the CERN SPS collider

We describe the apparatus used in experiment UA4 to study proton-antiproton elastic and inelastic interactions at the CERN SPS Collider. Elastically scattered particles, travelling at very small angles, are observed by detectors placed inside movable sections (“Roman pots”) of the SPS vacuum chamber. The deflection in the field of the machine quadrupoles allow the measurement of the particle momentum. Inelastic interactions are observed by a left-right symmetric system of trigger counter hodoscopes and drift-chamber telescopes. The apparatus reconstructs the interaction vertex and measures the pseudorapidity η of charged particles in the range 2.5 < 6η6 < 5.6.