Synthesis of furoates and 5-nitrofuroates in cyclohexane in the presence of cation-exchange resins

The use of ion-exchange resins for the esterification of furoic acid and 5-nitrofuroic acid was characterised by an excellent yield and the absence of side reactions, particularly when the reaction was carried out in cyclohexane in the presence of the resin, SPC 118. The use of this solvent for such a reaction in a biphasic medium is thus reported for the first time. This procedure might therefore be considered on a larger scale.     

A fully-digital and ultra-low-power front-end for differential capacitive sensors

In this paper, we present a simple, compact and low-power interface for differential capacitive sensors with a direct digital output. The complete system is composed with a current to voltage converter, an integrator, a comparator and a one-bit digital to analog converter as a feedback. The so-obtained Sigma–Delta modulator is able to deliver directly a bit stream with a ratio of logical ‘1’ directly proportional to the differential capacitance to be measured. A partially integrated prototype has been realized to demonstrate accuracy and non-linearity compatible with a 9-bit sensor.