An Optical Thermometer Exploiting Periodically Poled Lithium Niobate for Monitoring the Pantographs of High-Speed Trains

Optical thermometers have been widely investigated. Here, the temperature behavior of second harmonic generation (SHG) in periodically poled lithium niobate (PPLN) substrates is analyzed; indeed, the QPM tuning in PPLN devices and the obtained SHG efficiency depend on the crystal thermal expansion and dispersion, particularly in the case of guided propagation. Therefore, such devices are suitable to realize optical thermometers for demanding applications. This investigation originated with the request of a thermometer to be installed on the pantographs of high-speed trains. Therefore, it must be sturdy and reliable, but it has even to work in an EMD environment. The temperature behavior of the SHG was theoretically modeled and experimentally validated at 1550 nm, in both bulk propagation and APE channel waveguides. In the first case, by using a 10-mW source, which was obtained from a laser diode and a fiber amplifier, an accuracy of 0.3 degC was found. The pump power was about three orders of magnitude smaller in guided propagation. In view of testing on the trains, our investigation resulted in the design of a device without mechanical contacts with the input and output fibers. Since it works in free propagation, there are no serious alignment and packaging problems. The performances, which are expected to be the same of our tests, widely satisfy all the requirements for working effectively in a strongly hostile and EMD environment and for giving accurate measurements on a wide range of temperatures     

A new route to graphene starting from heavily ozonized fullerenes: Part 3 – an electron spin resonance study

It is shown that graphite oxide (GO) and both heavily ozonized C₆₀ and C₇₀ fullerenes, known as “fullerene ozopolymers,” are paramagnetic materials with a very strong electron spin resonance (ESR) signal at room temperature. When thermally annealed, the paramagnetic centers are gradually lost in large part. This occurs at 350°C in the case of GO, while for fullerene ozopolymers, a higher temperature is required, reaching the same results in the end. The half-width of ESR signal is linked to the distribution of paramagnetic centers. Once again, striking analogies were found in the half-width of the ESR signal measured on GO and fullerene ozopolymers, at least in the temperature range of 25–450°C. Similarly, the same g-factor values, which are diagnostic for understanding the chemical nature of paramagnetic centers, were found on both GO and fullerene ozopolymers in all ranges of temperature considered.     

Real-time risk monitoring in business processes: A sensor-based approach

This article proposes an approach for real-time monitoring of risks in executable business process models. The approach considers risks in all phases of the business process management lifecycle, from process design, where risks are defined on top of process models, through to process diagnosis, where risks are detected during process execution. The approach has been realized via a distributed, sensor-based architecture. At design-time, sensors are defined to specify risk conditions which when fulfilled, are a likely indicator of negative process states (faults) to eventuate. Both historical and current process execution data can be used to compose such conditions. At run-time, each sensor independently notifies a sensor manager when a risk is detected. In turn, the sensor manager interacts with the monitoring component of a business process management system to prompt the results to process administrators who may take remedial actions. The proposed architecture has been implemented on top of the YAWL system, and evaluated through performance measurements and usability tests with students. The results show that risk conditions can be computed efficiently and that the approach is perceived as useful by the participants in the tests.     

Development of virtual data acquisition systems based on multimedia internetworking

This paper proposes a novel approach centered on multimedia internetworking for the development of Distributed Virtual Instruments (DVI). Multimedia internetworking refers to network infrastructures, protocols, models, applications and techniques being currently deployed over the Internet to support multimedia applications, e.g., videoconferencing, video-on-demand, shared workspaces. It is applied to broaden the concept of virtual instrument and enable new measurement patterns leveraging efficiency and interactivity. A DVI is a virtual instrument split into possibly multiple and independent parts, sender and receiver, which are linked by real-time continuous media and control streams. Senders and receivers are built by using open, composable and modular components based on a time sensitive actor framework and glued by multimedia middleware. A prototype is described to demonstrate the potential and the benefits of the proposed approach.     

Inclusion Compounds of Dehydrocholic Acid with Solvents

The host-guest inclusion of various organic solvents within dehydrocholic acid has been studied and the selectivity of enclathration determined by competition experiments.     

Optimisation of a thick-film 10–400 N force sensor

The ring-on-ring bending principle allows the fabrication of simple, low-cost thick-film piezoresistive sensors for compressive forces in the 10–400 N range. However, some imperfections are encountered in its basic embodiment, such as relatively high force-signal hysteresis and nonrepeatability (up to ca. 5%). These shortcomings were studied in this work, and major improvements have been achieved. Hysteresis was found to be mainly due to friction at the outer support ring, and was considerably reduced by inserting a compliant silicone glue ring. The same glue ring was used to permanently bond the sensor to a rigid base, thereby giving well-defined and constant boundary conditions and also considerably improving the repeatability of the sensitivity. Overall, hysteresis and repeatability error were reduced down to a level of ca. 1%.     

Chemical and biological variability of hot pepper fruits (Capsicum annuum var. acuminatum L.) in relation to maturity stage

The aim of the present work was to evaluate the chemical composition and the radical-scavenging and antioxidant activities of hot pepper fruits (Capsicum annuum L. var. acuminatum) at three maturity stages (small green, green and red). GC–MS analysis of n-hexane and chloroform fractions showed a different composition between the three stages of ripening. The first stage of maturation (small green) showed the highest radical-scavenging activity (IC₅₀ of 129 μg/ml). Using the bovine brain peroxidation assay, the methanolic extract of green pepper showed significant antioxidant activity (IC₅₀ of 522 μg/ml). Addition of methanolic extract of red and green pepper inhibited oxidation of linoleic acid. Methanolic extract of red pepper showed greater antioxidative potency than the others (IC₅₀ of 3 μg/ml). The different composition of lipophilic compounds and the various amount of phenolics, showed in the three stage of ripening of C. annuum var. acuminatum fruits, modifies the antioxidant activity.     

Viscosimetric studies on 2-methoxyethanol + 1,2-dimethoxyethane binary mixtures from −10 to 80°c

The kinematic viscosities (v) were measured for nine binary solvent mixtures of 2-methoxyethanol (ME) + 1,2-dimethoxyethane (DME) at nineteen temperatures ranging from ?10 to +80°C. The experimental data have been used to test some empirical equations of the type v = v(T), v = v(X₁) and v = v(T, X₁). The viscosities of all the mixtures increase from the values of pure DME to that of ME as the mole fraction of ME increases, and always yield a negative excess property (v^E) at all the investigated temperatures. Furthermore, thermodynamic parameters of viscous flow have been evaluated on the basis of the Eyring theory. The excess free energy of activation of viscous flow (ΔG^E) vs X₂ plot suggests the presence of a stable hetero-adduct, having ME : DME = 1 : 1 stoichiometric ratio.     

Isolation of a hydroxytyrosol-rich extract from olive leaves (<Emphasis Type="Italic">Olea Europaea</Emphasis> L.) and evaluation of its antioxidant properties and bioactivity

In this research, a phenol extract of high hydroxytyrosol (OLPE) content was obtained from olive leaves (Olea europaea L.), and subsequently tested under different contexts. The method used to obtain the OLPE basically involved two steps: the use of strongly-acid aqueous steam, generated from 10% HCl (v/v) at 100°C, to directly hydrolyse the native complex phenols from integral olive leaves, and OLPE recovery by liquid–liquid extraction with ethyl acetate. Hydrolysis time was 1 h. Finally, the dried extract was dissolved in distilled water. The OLPE total phenols were determined by Folin–Ciocalteu’s method and by HPLC analysis. Hydroxytyrosol was about 92% of the total phenols present in OLPE, and the yield was about 0.2% on fresh leaves. OLPE showed antioxidant effects on different food lipids and did not inhibit lactic acid bacteria growth; however, it showed cytotoxicity on NIH/3T3 fibroblasts and human umbilical vein endothelial cells at concentrations higher than 0.32 mM (as hydroxytyrosol).     

A new flow reactor for the treatment of polluted water with microwave and ultrasound

Microwave (MW) and high‐intensity ultrasound (US) provide innovative techniques for the degradation of persistent organic pollutants (POPs). When Fenton's reagent is used to treat industrial wastes, organic pollutants are degraded by highly reactive hydroxyl radicals (HO·) that can oxidize almost any organic compound to carbon dioxide and water. These reactions, when carried out under US or MW, are faster and much more efficient. The present work assesses the combined effect of US and MW using a new flow reactor developed in our laboratory. In this 5 L pilot reactor the liquid was pumped in parallel through a modified domestic MW oven and through a cell where it was irradiated with two US generators working at 20 and 300 kHz, while MW irradiation took place in a modified domestic oven. We studied the degradation of 2,4‐dibromophenol (0.1 g L^?1 in water) by Fenton's reagent, assessing the contribution of each energy source to the overall effect, and found that MW and US‐300 kHz played the main role. A modest amount of oxidant (6 mL 30% H₂O₂ per 1 L of polluted water) sufficed to achieve complete degradation within 6 h, at which time organic compounds were no longer detectable. Even if no Fenton's reagent was added, about one half of the pollutant was degraded after 3 h irradiation. Copyright © 2007 Society of Chemical Industry