Low-cost Ratiometric Front-end for Industrial PRT Applications

Cost, size, speed, and measurement range limitations make the resistance bridge not always suitable for temperature measurements with platinum resistance thermometers (PRTs) in industrial applications. However, high-accuracy resistance thermometer systems are often needed in many industrial applications, where measurement performances comparable to resistance bridges are often needed at a lower cost and size. A tiny, portable, ratiometric front-end exploiting a 24-bit analog-to-digital converter (ADC) with Σ Δ modulator is described. It was designed to measure the resistance ratio between a 100 Ω industrial PRT (IPRT) and a reference resistor with repeatability to within a few parts in 106. Its small size makes it ideal for integration in the stem-handle assembly of a thermometric probe, enabling an early transmission of measurement data in digital form. The ADC-based system design, development, and performance testing are discussed. The system was investigated in the resistance ratio range from about 4 × 10-3 to 5 × 10-2. Furthermore, a comparison between the system performance and a commercial AC resistance bridge was carried out and the results reported in this paper. An accurate thermometer for industrial applications resulted from the above developments. The compactness of the devices enabled an implementation of the `smart sensor' concept in the measurement chain, where the front-end electronics was placed inside the IPRT handle together with an integrated memory to hold device identification, calibration coefficients, and the associated uncertainty. All data are transmitted to the readout module and are available to the user at a 5 Hz update rate for further analysis

Insight into the molecular properties of chitlac, a chitosan derivative for tissue engineering

Chitlac is a biocompatible modified polysaccharide composed of a chitosan backbone to which lactitol moieties have been chemically inserted via a reductive N-alkylation reaction with lactose. The physical-chemical and biological properties of Chitlac that have been already reported in the literature suggest a high accessibility of terminal galactose in the lactitol side chain. This finding may account for its biocompatibility which makes it extremely interesting for the production of biomaterials. The average structure and the dynamics of the side chains of Chitlac have been studied by means of NMR (nuclear Overhauser effect and nuclear relaxation) and molecular dynamics to ascertain this hypothesis. A complete assignment of the 1H and 13C NMR signals of the modified polysaccharide has been accomplished together with the determination of the apparent pKa values of the primary and secondary amines (6.69 and 5.87, respectively). NMR and MD indicated a high mobility of Chitlac side chains with comparable average internuclear distances between the two techniques. It was found that the highly flexible lactitol side chain in Chitlac can adopt two distinct conformations differing in the orientation with respect to the polysaccharide chain: a folded conformation, with the galactose ring parallel to the main chain, and an extended conformation, where the lactitol points away from the chitosan backbone. In both cases, the side chain resulted to be highly hydrated and fully immersed in the solven