Selection of an adsorbent for lead removal from drinking water by a point-of-use treatment device

The removal of lead from drinking water was investigated to develop a point-of-use water filter that could meet the regulation imposed by the new European Directive 98-83 lowering lead concentration in drinking water below 10 μg L⁻¹. The objective of this research was to assess the potential of different adsorbents (zeolites, resins, activated carbon, manganese oxides, cellulose powder) to remove lead from tap water with a very short contact time. To begin, the repartition of the lead species in a tap water and a mineral water was computed with the computer model CHESS. It showed that in bicarbonated waters lead is mainly under lead carbonate form, either in the aqueous or in the mineral phase. Batch experiments were then conducted to measure the equilibrium adsorption isotherms of the adsorbents. Then, for five of them, dynamic experiments in micro-columns were carried out to assess the outlet lead concentration level. Three adsorbents gave rise to a leakage concentration lower than 10 μg L⁻¹ and were then selected for prototypes experiments: chabasite, an activated carbon coated with a synthetic zeolite and a natural manganese oxide. The proposed method clearly showed that the measurement of equilibrium isotherms is not sufficient to predict the effectiveness of an adsorbent, and must be coupled with dynamic experiments.     

Preparation of 5‐Membered Rings via Radical Addition‐ Translocation‐Cyclization (RATC) Processes Mediated by Diethyl Thiophosphites

A practical method for the formation of thiophosphonates bearing functionalized monocyclic, fused bicyclic and spirocyclic residues is presented. The procedure requires the easily available terminal alkynes as starting materials as well as commercially and readily available reagents such as diethyl thiophosphite. The experimental procedure consists of a one‐pot process without any slow addition of one of the reagents.     

Work function tuning for flexible transparent electrodes based on functionalized metallic single walled carbon nanotubes

We present a method to control the work function of metallic carbon nanotube transparent electrodes by functionalization of the random network with metallic nanoparticles. Flexible functionalized electrodes with high transparency (～90%) can be obtained with work function values ranging from ～4.6 up to ～5.1 eV, depending on the nature of the nanoparticles. The work function values were obtained by comparative in situ Kelvin probe force microscopy under ultra high vacuum and ultraviolet photoelectron spectroscopy measurements. Interestingly, by appropriate choice of the metal source for functionalization, work function engineering can lead to work function values higher or lower than that for pristine metallic nanotubes. This could be of great interest for adjusting the work function of transparent electrodes to active layers in many optoelectronics devices.     

Local etching of copper films by the Scanning Electrochemical Microscope in the feedback mode: A theoretical and experimental investigation

A model of the Scanning Electrochemical Microscope (SECM) as a lithographic tool is presented and used to get quantitative kinetic information from lithographic experiments. It is illustrated in the specific case of the local etching by anodic dissolution of a copper substrate by the SECM in the feedback mode. A theoretical model presents the expected profile of the etched hole in the simple case of the positive feedback behaviour. A steady-state behaviour is expected for the dimensionless shape of the hole, which depends only on the tip-substrate separation distance. The hole depth is then expected to linearly depend on the etching time. The model is then confronted to different experimental conditions where a Cu substrate is locally oxidized by a tip-electrogenerated Fe(bpy)₃³⁺ oxidant. The experiments agree with the theoretical predictions (steady-state dimensionless profile and linear evolution of the depth with time). Even though the system behaves under positive feedback, the kinetics of the etching process can readily be extracted from the hole characterization and its conversion into Faradaic yield.     

Monitoring pitting corrosion of AISI 316L austenitic stainless steel by acoustic emission technique: Choice of representative acoustic parameters

This experimental work was aimed at investigating the monitoring of pitting corrosion by the acoustic emission (AE) technique, for pits developed by potentiostatic or galvanostatic polarization on two types of 316L austenitic stainless steels, in a 3% NaCl solution acidified to pH 2. The study of the evolution of AE global activity during the test showed the existence of a time delay before pits became emissive. This time delay and the AE events number rate measured during the propagation step of the pits are closely correlated with the sensitivity of the material towards pitting and with the polarization procedure. Moreover, the evolution of cumulative % of AE signals number versus selected acoustic parameters shows that rise time and counts number of signals appear to be discriminating acoustic parameters for monitoring pitting corrosion of austenitic stainless steels by acoustic emission technique in our experimental conditions, whatever the polarization procedure and the type of tested steel.     

Experimental setup for lensless imaging via soft x-ray resonant scattering

We have developed a setup for measuring holographically formed interference patterns using an integrated sample-mask design. The direct space image of the sample is obtained via a two-dimensional Fourier transform of the X-ray diffraction pattern. We present the details of our setup, commenting on the influence of geometrical parameters on the imaging capabilities. As an example, we present and discuss the results of test experiments on a patterned Co film.     

Probing photonic and optoelectronic structures by apertureless scanning near-field optical microscopy

This report presents the Apertureless Scanning Optical Near-Field Microscope as a powerful tool for the characterization of modern optoelectronic and photonic components with sub-wavelength resolution. We present an overview of the results we obtained in our laboratory over the past few years. By significant examples, it is shown that this specific probe microscopy allows for in situ local quantitative study of semiconductor lasers in operation, integrated optical waveguides produced by ion exchange (single channel or Y junction), and photonic structures.     

A new identification method of viscoelastic behavior: Application to the generalized Maxwell model

This paper focuses on the generalized Maxwell model (GMM) identification. The formulation of the transfer function of the GMM is defined, as well as its asymptotes. To compare identification methods of the parameters of the GMM, a test transfer function and two quality indicators are defined. Then, three graphical methods are described, the enclosing curve method, the CRONE method and an original one. But the results of graphical methods are not good enough. Thus, two optimization recursive processes are described to improve the results of graphical methods. The first one is based on an unconstrained non-linear optimization algorithm and the second one is original and allows constraining identified parameters. This new process uses the asymptotes of the modulus and the phase of the transfer function of the GMM. The result of the graphical method optimized with the new process is very accurate and fast.