SilverSil: A New Class of Antibacterial Materials of Broad Scope

Consisting of organically modified silica (ORMOSIL) physically doped with Ag nanoparticles, the SilverSil new class of antibacterial materials of broad scope reported herein shows remarkably high and stable activity against representative Gram-positive and Gram-negative bacteria. The low cost, ease of application and excellent health and environmental profile of SilverSil hybrid glassy coatings open the route to their widespread utilization across domestic, hospital, school, industrial and commercial environments and in consumer products.     

The Triplet Hydroxyl Radical Complex of Phosphorus Monoxide

Phosphorus monoxide (^.PO) is a key intermediate in phosphorus chemistry, and its association with the hydroxyl radical (^.OH) to yield metaphosphorous acid (cis-HOPO) contributes to the chemiluminescence in the combustion of phosphines. When photolyzing cis-HOPO in an Ar-matrix at 2.8 K, the simplest dioxophosphorane HPO₂ and an elusive hydroxyl radical complex (HRC) of ^.PO form. This prototypical radical-radical complex reforms into cis-HOPO at above 12.0 K by overcoming a barrier of 0.28±0.02 kcal mol⁻¹. The vibrational spectra of this HRC and its D- and ¹⁸O-isotopologues suggest a structure of ^.OH⋅⋅⋅OP^., for which a triplet spin multiplicity with a binding energy of −3.20 kcal mol⁻¹ has been computed at the UCCSD(T)-F12a/aug-cc-pVTZ level.     

Study of thermal and chemical effects on cellulase enzymes: Viscosity measurements

The behaviour of cellulase enzymes in phosphate saline buffer has been studied over a wide range of temperatures and enzyme concentrations by using viscosity measurements. To characterize the conformation change of cellulase versus temperature and chemical denaturants, such as guanidinium chloride (GdmCl) and urea, the information about the intrinsic viscosity and the hydrodynamic radius are necessary. The dependence of the intrinsic viscosity and the hydrodynamic radius in its random coil conformation on temperature and denaturant concentration were studied. Our results and discussions are limited to the dilute regime of concentration because of abnormalities in conformation observed in the very dilute regime due to the presence of capillary absorption effects.     

Non-existence of minimizers for a nonlinear membrane plate under compression

The classical equations of a nonlinearly elastic membrane plate, made of Saint Venant–Kirchhoff material, have been justified by Fox et al. (Arch. Rational Mech. Anal. 124 (2) (1993) 157–199). We show that, under compression, the associated minimization problem admits no solution. The proof is based on a result of non-existence of minimizers of non-convex functionals due to Dacorogna and Marcellini (Arch. Rational Mech. Anal. 131 (4) (1995) 359–399). We generalize the application of their result from plane elasticity to membrane plates. To cite this article: K. Trabelsi, C. R. Acad. Sci. Paris, Ser. I 337 (2003).     

Physicochemical and rheological properties of thickeners produced from Tunisian clays

Modification of two samples of Tunisian clays of the type of natural smectites with organic derivatives of ammonium salts was studied. The physicochemical properties of the modified products and the possibility of their use as components of lubricating oils were analyzed. Published in Russian in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 3, pp. 387–392. This article was submitted by the authors in English.     

Mise en évidence par spectroscopie infrarouge des espèces Ni(PH3)n(n = 1–4) Isolées en matrice

Ni(PH₃)_n species (where n = 1–4) were obtained by a co-condensation reaction of nickel vapour with phosphine, and stabilized at a low temperature in argon matrices. Infrared spectra in the Ni-P stretching vibration region provided evidence for their formation. Solid Ni(PH₃)₄ was isolated after removal of excess PH₃.     

FE simulation of human trachea swallowing movement before and after the implantation of an endoprothesis

Background and aims

Nowadays interventions associated to the implantation of tracheal stents in patients with airway pathologies, are a very common surgery that in the post-operating period can bear many problems such as migration of the stent, development of granulation tissue at the edges of the stent with overgrowth of the tracheal lumen, or accumulation of secretions inside the prosthesis. Among the movements that trachea carries out, swallowing seems to drive harmful consequences for the tracheal tissues surrounding the prosthesis. In this work a finite element model of a human trachea has been developed and used to analyze its behavior during swallowing.

Material and methods

In the present work, a complete human trachea finite element model based on experimental study was developed. The real swallowing movement of two patients before and after the implantation of Dumon prosthesis was used to simulate and then analyze the effect that the tracheal implant has on the stress response of the trachea and on the physiological capacity to swallow.

Results

In both studied cases with an implanted Dumon prosthesis, patients showed a decrease of their ability to swallow; one lost 26.4% and the other one 18.9% of their tracheal ascending movements. Besides, the prosthesis implantation caused an increase of the stresses located in the superior contact border between the tracheal wall and the prosthesis. It could be seen that the resulting force equivalent to the elevating tracheal muscle forces for degluting, was around F = 13.5 N for the two patients both before and after the stent implantation.

Conclusion

The implantation of a Dumon prosthesis modifies the mechanical response of the trachea altering its stress distribution and its ascending movement.     

Expanded Bed Chromatography as a Tool for Nanoparticulate Separation: Kinetic Study and Adsorption of Protein Nanoparticles

Expanded bed adsorption was investigated together with its suitability for the practical recovery of nanoparticulate mimics of products such as plasmid DNA and viruses as putative gene therapy vectors. The study assessed the binding of protein nanoparticles fabricated from bovine serum albumin (BSA) with average size of 80 nm as a model system and viral size/charge mimic to the streamline DEAE adsorbent in the expanded bed column chromatography. The adsorption kinetics and adsorption mechanism for the BSA nanoparticles on the adsorbent were studied. In batch adsorption studies, the factors nanoparticle concentration, contact time and adsorbent amount, affecting adsorption isotherms were investigated. Subsequently the data were regressed against the Lagergren equation, which represents a first-order kinetics equation and also against a pseudo-second-order kinetics equation. The results demonstrated that the adsorption process followed a Langmuir isotherm equation. The kinetics of the adsorption process followed a pseudo-second-order kinetics model with a rate constant value of 0.025 g mg^?1 min^?1. The dynamic binding capacity of the BSA nanoparticles on an expanded bed was calculated. The recovery of the nanoparticles was more than 85%.     

Global-in-time existence of solutions to the multiconfiguration time-dependent Hartree–Fock equations: A sufficient condition

The multiconfiguration time-dependent Hartree–Fock (MCTDHF for short) system is an approximation of the linear many-particle Schrödinger equation with a binary interaction potential by nonlinear “one-particle” equations. MCTDHF methods are widely used for numerical calculations of the dynamics of few-electron systems in quantum physics and quantum chemistry, but the time-dependent case still poses serious open problems for the analysis, e.g. in the sense that global-in-time existence of solutions is not proved yet. In this letter we present the first result ever where global existence is proved under a condition on the initial datum that it has to be somewhat close to the “ground state”.