Elaboration,characterization and study of a new hybrid chitosan/ceramic membrane for affinity membrane chromatography

A new kind of metal affinity membrane based on a ceramic support was prepared. It was elaborated in four steps: (i) deposition of a chitosan layer in order to functionalize the ceramic support, (ii) cross-linking with epichlorohydrin to stabilise the polymer layer and to enable the grafting, (iii) iminodiacetic acid grafting, (iv) Cu²⁺ adsorption. Due to the ceramic support, this membrane is highly resistant and the chitosan layer brings its biocompatibility properties. Each step of the membrane elaboration was studied and the membrane structure was characterized. Both thin coating of the polymer on the alumina grains of the support and the chemical modification of the membrane were proved. Then, bovine serum albumin (BSA) was used as a model protein to test protein retention of the affinity membrane. The protein/membrane interactions were investigated showing that some non-specific ones are involved. Finally, the effect of buffer concentration was checked and it appears that, in the studied range, an increase of the buffer concentration entailed a limitation of the non-specific interactions inducing a better BSA recovering and a higher selectivity.     

Psychoacoustics of in-car switch buttons: From feelings to engineering parameters

The car interior is becoming quieter and other sounds are now exposed to user perception, such as the sound produced by interface buttons when actuated. So, the functional role of the button sound on interface operation and its aesthetic and emotional role on the user experience are now more important than before. However, little research and design effort has been paid to understand how to design buttons that produce a pleasant sound. Moreover, the button’s sound requirements received by interface manufacturers are ill-defined, insufficient or even inexistent, and consequently their conversion into specifications for manufacturing is problematic and leads to long and costly development processes. The purpose of this paper is to contribute to identify relevant acoustic parameters that explain the users sound preferences. Data on preference subjective judgments were collected and buttons acoustic signals were measured allowing the development of preference models based on partial least squares regression and neural networks methods. The former was successful in selecting the relevant parameters to describe the preference ratings of the buttons sound. The later, dealing with the non-linear nature of acoustic perception, was able to predict preferences based on the relevant parameters.     

The [U2F12]2− Anion of Sr[U2F12]

The D_2h‐symmetric dinuclear complex anion [U₂F₁₂]^2? of pastel green Sr[U₂F₁₂] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge‐linked monocapped trigonal prisms, the U^V atoms are therefore seven‐coordinated. This leads to a U–U distance of 3.8913(6) Å. A weak U^V–U^V interaction is observed for the dinuclear [U₂F₁₂]^2? complex and described by the antiferromagnetic exchange J_exp of circa ?29.9 cm^?1. The crystalline compound can be easily prepared from SrF₂ and β‐UF₅ in anhydrous hydrogen fluoride (aHF) at room temperature. It was studied by means of single crystal X‐ray diffraction, IR, Raman and UV/VIS spectroscopy, magnetic measurements, and by molecular as well as by solid‐state quantum chemical calculations.     

Determination of four acidic nonsteroidal anti‐inflammatory drugs in wastewater samples by dispersive liquid–liquid microextraction based on solidification of floating organic droplet and high‐performance liquid chromatography

A simple, environmentally friendly, and sensitive dispersive liquid–liquid microextraction based on solidification of floating organic droplet for the extraction of four acidic nonsteroidal anti‐inflammatory drugs (ketoprofen, naproxen, ibuprofen, and diclofenac) from wastewater samples subsequent by high‐performance liquid chromatography analysis was developed. The influence of extraction parameters such as pH, the effect of solution ionic strength, type of extraction solvent, disperser solvent, and extraction solvent volume were studied. High enrichment factors (283–302) were obtained through the developed method. The method provides good linearity (r > 0.999) in a concentration range of 1–100 μg/L, good intra‐ and inter‐day precision (relative standard deviation < 7%) and low limits of quantification. The relative recoveries of the selected compounds were situated over 80% both in synthetic and real water samples. The developed method has been successfully applied for the analysis of the selected compounds in wastewater samples.     

Generalizations of a Theorem of Datko and Pazy

This note gives necessary and sufficient conditions for exponential stability of semigroups of linear operators in Banach spaces. Generalizations of a well-known result due to Datko, Pazy and Neerven are obtained for the case of semigroups of operators that are not strongly continuous.     

Biomimetic Approach for Highly Selective Artificial Water Channels Based on Tubular Pillar[5]arene Dimers

Artificial water channels mimicking natural aquaporins (AQPs) can be used for selective and fast transport of water. Here, we quantify the transport performances of peralkyl-carboxylate-pillar[5]arenes dimers in bilayer membranes. They can transport ≈10⁷ water molecules/channel/second, within one order of magnitude of the transport rates of AQPs, rejecting Na⁺ and K⁺ cations. The dimers have a tubular structure, superposing pillar[5]arene pores of 5 Å diameter with twisted carboxy-phenyl pores of 2.8 Å diameter. This biomimetic platform, with variable pore dimensions within the same structure, offers size restriction reminiscent of natural proteins. It allows water molecules to selectively transit and prevents bigger hydrated cations from passing through the 2.8 Å pore. Molecular simulations prove that dimeric or multimeric honeycomb aggregates are stable in the membrane and form water pathways through the bilayer. Over time, a significant shift of the upper vs. lower layer occurs initiating new unexpected water permeation events through toroidal pores.