Temperature Measurement in Small-Scale Flows with Digital Moiré Deflectometry

Abstract

This article explores the potential of Moiré deflectometry for measuring the temperature field in quasi-two-dimensional small scale flows. The research shows that digital Moiré deflectometry combined with two-dimensional Fourier transform for phase map extraction constitutes a useful diagnostic tool for acquiring the fluid temperature with sufficient sensibility and spatial resolution in small two-dimensional or axisymmetric arrangements with negligible pressure variations. The results obtained in the thermal boundary layer of a flat plate are in good agreement with both thermocouple measurements and numerical results.     

Azomethine Ylides from Nitrones: Using Catalytic nBuLi for the Totally Stereoselective Synthesis of trans‐2‐Alkyl‐3‐oxazolines

The cycloaddition of azomethine ylide N‐oxides (nitrone ylides) with aldehydes provides 3‐oxazolines in a completely stereoselective manner in the presence of a catalytic amount of n‐butyllithium. The process involves an initial nucleophilic attack on the aldehyde, followed by intramolecular oxygen addition to the nitrone moiety and lithium‐assisted elimination of water, regenerating the catalytic species. Various Li‐based catalytic systems are possible and the in situ generated water is required for continuing the catalytic cycle. The best results are observed with 20 mol % of n‐butyllithium, whereas the use of stoichiometric amounts inhibit the rate of catalysis. Experimental, spectroscopic, and computational mechanistic studies have provided evidence of lithium‐ion catalysis and rationalized several competing catalytic pathways