Stereoscopic PIV measurements of a turbulent boundary layer with a large spatial dynamic range

The flow in a streamwise/wall-normal plane of a turbulent boundary layer at moderate Reynolds number (Re _θ = 2,200) is characterized using two stereo PIV systems just overlapping in the streamwise direction. The aim is to generate SPIV data for near-wall turbulence with enough spatial dynamic range to resolve most of the coherent structures present in the flow and to facilitate future comparisons with direct numerical simulations. This is made possibly through the use of four cameras with large CCD arrays (4,008 px × 2,672 px) and through a rigorous experimental procedure designed to minimize the impact of measurement noise on the resolution of the small scales. For the first time, both a large field of view [S _x ; S _y ] = [2.6δ; 0.75δ] and a high spatial resolution (with an interrogation window size of 13.6⁺) have been achieved. The quality of the data is assessed through an analysis of some of the statistical results such as the mean velocity profile, the rms and the PDF of the fluctuations, and the power spectra.     

Structure et stabilité thermique des deux formes du formiate de magnesium dihydraté

We have prepared and studied a new form of dehydrated magnesium formate. This form is orthorhomic (a = 8.710(2), Å, b = 8.427(2), Å, c = 7.477(2)Å, Z = 4, Pbca). The structure (R = 0.060, R_w = 0.049) shows that the Mg are bonded together by formate bridges, thus forming sheets parallel to the x0y plane. Tridimensional cohesion is secured by water molecules inserted between sheets; these water molecules are bonded to the Mg of one sheet and, by hydrogen bonds, to two formate groups of the next neighbor sheet. From the structural comparison of the two forms (monoclinic and orthorhomic), a lower stability of the orthorhombic variety was predicted. This was confirmed by study of the thermal decomposition under argon atmosphere as observed by thermogravimetric and thermodifferential analysis, powder X-ray diffraction and infrared spectra.     

The use of bioindicators for monitoring the heavy-metal status of the environment

Biomonitoring is a method of observing the impact of external factors on ecosystems and their development over a long period, or of ascertaining differences between one location and another. A monitor suitable for the subject of the investigation must be chosen, and the comparability of the element concentrations thus determined (both within the investigation and with other studies) must be ensured by adhering to precise sampling guidelines. In addition to the small amount of equipment required, the advantages of biomonitoring lie in the ecosystem approach that permits conclusions going beyond the biomonitor itself. Attention has to be given to the factors that may affect element concentrations and which can lead to incorrect statements if ignored.     

Metasurface‐Based Molecular Biosensing Aided by Artificial Intelligence

Molecular spectroscopy provides unique information on the internal structure of biological materials by detecting the characteristic vibrational signatures of their constituent chemical bonds at infrared frequencies. Nanophotonic antennas and metasurfaces have driven this concept towards few‐molecule sensitivity by confining incident light into intense hot spots of the electromagnetic fields, providing strongly enhanced light‐matter interaction. In this Minireview, recently developed molecular biosensing approaches based on the combination of dielectric metasurfaces and imaging detection are highlighted in comparison to traditional plasmonic geometries, and the unique potential of artificial intelligence techniques for nanophotonic sensor design and data analysis is emphasized. Because of their spectrometer‐less operation principle, such imaging‐based approaches hold great promise for miniaturized biosensors in practical point‐of‐care or field‐deployable applications.     

Zur elektrolytischen Bestimmung des Kupfers und Nickels

Ohne Zusammenfassung     

Study of the broadening of the rotational Raman lines of CO2 perturbed by rare gases

This paper presents the results of an experimental and theoretical study of the broadening of the rotational Raman lines of the linear molecule CO₂ perturbed by rare gases: helium, neon and argon. In the first part, the experimental set-up and the method to deduce linewidths from the spectra are presented. This method is similar to that used by Welsh et al. although we take into account the contribution of the molecules in the (01¹0) vibrational state for which the rotational quantum number J can be odd. The results for the pressure broadening coefficient are then given for several values of J. We then briefly recall how one can derive collision cross sections from the measured linewidths. The second part is devoted to an attempt to interpret the experimental results in terms of the theory of the Raman linewidths developed by Van Kranendonk. After recalling briefly the assumptions used in that theory and discussing the intermolecular potentials that are used, we present the results of numerical calculations performed with several types of anisotropic interaction potentials between CO₂ and the atom of rare gas. We reach the conclusion that the approximate methods used by Van Kranendonk (matrix elements of the evolution operator S computed by second order perturbation theory) are probably inadequate to calculate the effect of elastic collisions that disorient the molecule. It is suggested that it might be advantageous to consider anisotropic forces of shorter range than the anisotropic London dispersion forces derived from an r^-6 potential.     

Polymer-supported tetrafluorophenol: a new activated resin for chemical library synthesis

A new tetrafluorophenol activated resin that facilitates the use of 19F NMR to quantitate loading is presented. This new resin provides a useful tool for acylation, and a novel activated polymeric sulfonate ester to generate sulfonamides. This activated resin reacts with a wide scope of N-nucleophiles including primary and secondary amines, and anilines. This new activated resin methodology provides a powerful tool for pure single-compound library synthesis.     

Synthesis and diversity analysis of lead discovery piperazine-2-carboxamide libraries

A Lead Discovery Library ofpiperazine-2-carboxamide derivatives was produced forgeneral screening. This paper discloses two novelsolid phase synthetic routes used to produce 15 000single compounds via the Irori directed sortingtechnique. Computational methods such as reagentclustering and library profiling were used to maximizereagent diversity and optimize pharmacokineticparameters. The results of a four center pharmacophoreanalysis revealed the added diversity gained by usingtwo independent synthetic routes.     

Determination des structures du cyclooctadiene dichloro palladium et du cyclooctadiene-1,5 (phenyl sulfonyl methanato) chloro palladium

A crystalline derivative is formed when lithiated phenyl methyl sulfone is treated with CODPdCl₂. The X-ray structure determination is described. The anionic carbon is tetrahedral.