Simultaneous temperature and 2D velocity measurements in a turbulent heated jet using combined laser-induced fluorescence and LDA

 This paper presents an efficient technique for the characterization of thermal transport properties in turbulent flows. The method is based on the temperature dependence of fluorescence, induced by laser radiation, of an organic dye. The laser-induced fluorescence technique is combined with 2D laser Doppler anemometry, in order to measure in the same sample volume simultaneously and instantaneously the temperature and velocity. The technique is demonstrated on a turbulent heated round jet: the mean and fluctuating dynamic and thermal fields are investigated, and the temperature-velocity cross-correlations are determined in order to characterize the turbulent diffusivity and the turbulent Prandtl number. Received: 30 October 1997/Accepted: 14 July 1998     

The action of a few permutations on r-tuples is quickly transitive

We prove that for every r and d≥2 there is a C such that for most choices of d permutations π₁, π₂,…,π_d of S_n, the following holds: for any two r-tuples of distinct elements in {1,…,n}, there is a product of less than C log n of the π_is which map the first r-tuple to the second. Although we came across this problem while studying a rather unrelated cryptographic problem, it belongs to a general context of which random Cayley graph quotients of S_n are good expanders. © 1998 John Wiley & Sons, Inc. Random Struct. Alg., 12: 335–350, 1998     

On the validity of crystallization kinetics parameters derived from the depolarized light intensity (DLI) technique: An experimental study of polyvinylidene fluoride

Although the depolarized light intensity technique has been known for some decades, the time dependence of light intensity does not yet seem to be well understood. In this article, devoted to the crystallization kinetics of polyvinylidene fluoride (PVDF), we present some of the problems associated with quantitative analysis. Parameters such as incident light intensity—in combination with the detection system—and specimen thickness are shown to dramatically affect the apparent kinetics. Experiments on single spherulites grown in very thin films can help interpret the intensity–time curve. Our results demonstrate that care should be taken when comparison is made between DLI and differential scanning calorimetry. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 997–1008, 1999     

Synthetic Utility of Stable Phosphanylcarbenes: Synthesis and Crystal Structure of an α‐(Lithiomethylene)phosphorane

The first crystallographically characterized phosphonium yldiide 2 was obtained in a simple reaction by addition of n‐butyllithium to the stable phosphanyl(silyl)carbene 1 . R=cHex₂N.     

Entire Solution in Cylinder-Like Domains for a Bistable Reaction–Diffusion Equation

We construct nontrivial entire solutions for a bistable reaction–diffusion equation in a class of domains that are unbounded in one direction. The motivation comes from recent results of Berestycki et al. (Calc Var Partial Differ Equ 55(3):1–32, 2016) concerning propagation and blocking phenomena in infinite domains. A key assumption in their study was the “cylinder-like” assumption: their domains are supposed to be straight cylinders in a half space. The purpose of this paper is to consider domains that tend to a straight cylinder in one direction. We need a different approach based on the long time stability of the bistable wave in heterogeneous media. We also prove the existence of an entire solution for a one-dimensional problem with a non-homogeneous linear term.     

Magnetodielectric coupling in Ca3Co2O6 triangular Ising lattice

Geometric frustration in magnetic systems is a key ingredient for magnetodielectric coupling. Ca₃Co₂O₆ system is a model of triangular Ising lattice and presenting exotic magnetic properties. With a partially disordered antiferromagnetic ground state and two steps in magnetisation to a ferrimagnetic state and to a ferromagnetic state, this oxide is a good system for studying the effect of frustration in magnetodielectric coupling. Dielectric constant measurements of single crystals of Ca₃Co₂O₆ have been done showing the sensitivity of this technique to frustration.