Influence of the nature of the polycation on the adsorption kinetics and on exchange processes in polyelectrolyte multilayer films

The deposition of polyelectrolyte multilayer films (PEMs) appears more and more as a versatile tool to functionalize a broad range of materials with coatings having controlled thicknesses and properties. To increase the control over the properties of such coatings, a good knowledge of their deposition mechanism is required. Since Cohen Stuart et al. (Langmuir 18 (2002) 5607-5612) showed that the adsorption of one polyelectrolyte could induce desorption of polyelectrolyte complexes instead of regular deposition, more and more findings highlight peculiarities in the deposition of such films. Herein we demonstrate that the association of sodium polyphosphate (PSP) as the polyanion and either poly(-L-lysine hydrobromide) (PLL) or poly(allylamine chloride) (PAH) as the polycations may lead to non-monotonous film deposition as a function of time. Complementary, films containing PSP and PLL can be obtained from a (PLL-HA)(n) template films after the exchange of HA (hyaluronic acid) from the sacrificial template by PSP from the solution. This exchange is accompanied by pronounced film erosion. However, when starting from a (PAH-HA)(n) template, the film erosion and exchange due to the contact with PSP is by far less pronounced, nevertheless the film morphology changes. These findings show that the nature of the polycation used to deposit the PEM film may have a profound influence of the film's response to a competing polyanion.     

Actions of Noncompact Semisimple Groups on Lorentz Manifolds

The above title is the same, but with “semisimple” instead of “simple,” as that of a notice by Nadine Kowalsky. There, she announced many theorems on the subject of actions of simple Lie groups preserving a Lorentz structure. Unfortunately, she published proofs for essentially only half of the announced results before her premature death. Here, using a different, geometric approach, we generalize her results to the semisimple case, and give proofs of all her announced results. Received: May 2006, Revision: February 2007, Accepted: March 2007     

Corrigendum to: “Fractional Functional Differential Inclusions with Finite Delay” [Nonlinear Anal. 70(5) (2009) 2091–2105]

We correct an error made in the paper (J. Henderson and A. Ouahab, Fractional Functional Differential Inclusions with Finite Delay [Nonlinear Anal. 70(5) (2009) 2091–2015]), in an application of Theorem 4.1 in the proof of Theorem 4.2. We have revised the statement of Theorem 4.2 so that Theorem 4.1 is now applicable in its proof.     

Kinetic models of chemotaxis towards the diffusive limit: asymptotic analysis

The paper is devoted to the study of the asymptotic behavior of the solutions of a kinetic model describing chemotaxis phenomena. Our interest focuses on the case, where the diffusion part dominates the chemotaxis part in the limit. More in detail, we prove that the solution of kinetic model exists globally and converges to a solution of diffusive limit. Copyright © 2015 John Wiley & Sons, Ltd.     

Theoretical study of the νO–H IR spectra for the hydrogen bond dimers from the polarized spectra of glutaric and 1-naphthoic acid crystals: Fermi resonances effects

A full quantum theoretical model is proposed to study the ν_O–H experimental IR line shapes of polarized crystalline glutaric and 1-naphthoic acid dimer crystals at room and liquid nitrogen temperatures. This work is an application of a previous model [M. E-A. Benmalti, D. Chamma, P. Blaise, and O. Henri-Rousseau, J. Mol. Struct. 785 (2006) 27–31] by accounting for Fermi resonances. The approach is dealing with the strong anharmonic coupling, Davydov coupling, multiple Fermi resonances between the first harmonics of some bending modes and the first excited state of the symmetric combination of the two ν_O–H modes and the quantum direct and indirect relaxation.Numerical results show that mixing of all these effects allows to reproduce satisfactorily the main features of the experimental IR line shapes of crystalline hydrogenated and deuterated glutaric and 1-naphthoic acid crystals and are expected to provide efficient of Fermi resonances effects.     

Facile preparation of glyconanoparticles and their bioconjugation to streptavidin

Well-defined glycopolymers containing linear and cyclic carbohydrate moieties as pendent groups were prepared by reversible addition fragmentation chain transfer polymerization (RAFT). The RAFT synthesized glycopolymers were used for the aqueous synthesis of stabilized glyconanoparticles. The in situ reduction of the glycopolymers and HAuCl4 resulted in the formation of highly stable modified gold nanoparticles with diameters ranging from 40 to 80 nm in aqueous media. Multifunctional glyconanoparticles were also generated in the presence of varying amounts of biotinylated-polyethyleneglycol (bio-PEG-SH) having terminal thiol groups. The gold nanoparticles underwent aggregation in the presence of streptavidin as revealed by UV-vis spectroscopy. The availability of the biotin for conjugation to streptavidin was also confirmed using surface plasmon resonance (SPR).     

Global rigidity of holomorphic Riemannian metrics on compact complex 3-manifolds

We study compact complex 3-manifolds M admitting a (locally homogeneous) holomorphic Riemannian metric g. We prove the following: (i) If the Killing Lie algebra of g has a non trivial semi-simple part, then it preserves some holomorphic Riemannian metric on M with constant sectional curvature; (ii) If the Killing Lie algebra of g is solvable, then, up to a finite unramified cover, M is a quotient Γ\G, where Γ is a lattice in G and G is either the complex Heisenberg group, or the complex SOL group. S. Dumitrescu was partially supported by the ANR Grant BLAN 06-3-137237.     

Boosting COVID-19 Image Classification Using MobileNetV3 and Aquila Optimizer Algorithm

Currently, the world is still facing a COVID-19 (coronavirus disease 2019) classified as a highly infectious disease due to its rapid spreading. The shortage of X-ray machines may lead to critical situations and delay the diagnosis results, increasing the number of deaths. Therefore, the exploitation of deep learning (DL) and optimization algorithms can be advantageous in early diagnosis and COVID-19 detection. In this paper, we propose a framework for COVID-19 images classification using hybridization of DL and swarm-based algorithms. The MobileNetV3 is used as a backbone feature extraction to learn and extract relevant image representations as a DL model. As a swarm-based algorithm, the Aquila Optimizer (Aqu) is used as a feature selector to reduce the dimensionality of the image representations and improve the classification accuracy using only the most essential selected features. To validate the proposed framework, two datasets with X-ray and CT COVID-19 images are used. The obtained results from the experiments show a good performance of the proposed framework in terms of classification accuracy and dimensionality reduction during the feature extraction and selection phases. The Aqu feature selection algorithm achieves accuracy better than other methods in terms of performance metrics.     

Learning course adjustments during arm movements with reversed sensitivity derivatives

Background

To learn, a motor system needs to know its sensitivity derivatives, which quantify how its neural commands affect motor error. But are these derivatives themselves learned, or are they known solely innately? Here we test a recent theory that the brain's estimates of sensitivity derivatives are revisable based on sensory feedback. In its simplest form, the theory says that each control system has a single, adjustable estimate of its sensitivity derivatives which affects all aspects of its task, e.g. if you learn to reach to mirror-reversed targets then your revised estimate should reverse not only your initial aiming but also your online course adjustments when the target jumps in mid-movement.

Methods

Human subjects bent a joystick to move a cursor to a target on a computer screen, but the cursor's motion was reversed relative to the joystick's. The target jumped once during each movement. Subjects had up to 4000 trials to practice aiming and responding to target jumps.

Results

All subjects learned to reverse both initial aiming and course adjustments.

Conclusions

Our study confirms that sensitivity derivatives can be relearned. It is consistent with the idea of a single, all-purpose estimate of those derivatives; and it suggests that the estimate is a function of context, as one would expect given that the true sensitivity derivatives may vary with the state of the controlled system, the target, and the motor commands.