Preparation of novel methyl methacrylate/fluorinated silsesquioxane copolymer film with low surface energy

Random copolymers of methyl methacrylate and fluorinated polyhedral oligomeric silsesquioxane (F-POSS) were synthesized and the corresponding thin films were prepared from solvent casting. Their microstructure was confirmed by ¹H NMR, elemental analysis and GPC. Separation occurs in the bulk of the film during solvent evaporation which can be evidenced by Transmission Electron Microscopy, TEM, with POSS-rich nanophase sizes from 20 to 50 nm. Nanostructuration is attributed to the self-assembly of F-POSS due to the cluster-cluster interactions resulting from the nature of their ligands, i.e., cycloaliphatic ligands and perfluorinated chains. Thermogravimetric analysis was used to investigate the thermal degradation temperature. It was shown that when F-POSS content is higher than 2.8 mol%, the incorporation of F-POSS could improve the thermal stability of PMMA significantly. In addition, it was shown that these fluorinated POSS-based copolymer surfaces could reduce the surface energy and could be used to design water-repellant nanocomposite coatings.

     

Contributions of talker characteristics and spatial location to auditory streaming

To examine whether auditory streaming contributes to unmasking, intelligibility of target sentences against two competing talkers was measured using the coordinate response measure (CRM) [Bolia et al., J. Acoust. Soc. Am. 107, 1065-1066 (2007)] corpus. In the control condition, the speech reception threshold (50% correct) was measured when the target and two maskers were collocated straight ahead. Separating maskers from the target by +/-30 degrees resulted in spatial release from masking of 12 dB. CRM sentences involve an identifier in the first part and two target words in the second part. In experimental conditions, masking talkers started spatially separated at +/-30 degrees but became collocated with the target before the scoring words. In one experiment, one target and two different maskers were randomly selected from a mixed-sex corpus. Significant unmasking of 4 dB remained despite the absence of persistent location cues. When same-sex talkers were used as maskers and target, unmasking was reduced. These data suggest that initial separation may permit confident identification and streaming of the target and masker speech where significant differences between target and masker voice characteristics exist, but where target and masker characteristics are similar, listeners must rely more heavily on continuing spatial cues.     

New hybrid organic-inorganic nanocomposites based on functional [Ti16O16(OEt)24(OEMA)8] nano-fillers

New hybrid nanocomposites based on a methacrylate functionalized titanium-oxo cluster as nano-cross-linker show improved mechanical properties, optical transparency and photochromic activity.     

Synthesis and properties of thiazoline based ionic liquids derived from the chiral pool

A novel class of chiral ionic liquids derived from amino alcohols is prepared in multi-gram scale. Their potential in chiral recognition is shown in a preliminary example with racemic Mosher's acid salt.     

The origin of the electrode effect in various electrolytes

The problem of the origin of electrode effects in various electrolytes is studied on the ground of Fourier's equation. Thus the electrolysis time elapsed before the occurrence of an electrode effect is shown to be equal to the calculated time which is the time necessary to bring the temperature of the electrolyte surrounding the electrode up to its boiling point. Then we can conclude in all cases investigated that the electrode effects are induced by a Joule effect heating of the electrolyte.     

Ab-initio study of localization of an excess electron in sodium halide clusters

The equilibrium geometries of Na _n F _n and Na _n F _n?1 are optimized forn=2, 3, 4 at the SCF level. The Na _n F _n molecules appear as formed by Na⁺ and F^? ions. The paper studies the localization of the excess electron in the Na _n F _n?1 molecules. Na _n F _n?1 is obtained by removing from Na _n F _n a fluorine atom, and the excess electron takes the place of this lacking center, and allows a weak bond between the neighbouring Na atoms. Secondary minimum geometries, for which the excess electron has no defined place, are also studied.     

Adsorption of lysozyme on a hemodialysis sulfonated polyacrylonitrile membrane, with and without preadsorbed poly(ethyleneimine) on the external faces

We present the influence of pH, from pH 4 to 10, with a focus on the neutral range, on the adsorption of lysozyme (isoelectric point pI=11) on a sulphonated membrane and the same membrane pre-treated with poly(ethyleneimine) (PEI). We found a steep increase of the adsorbed amount above pH 6 in phosphate buffer. The adsorbed amount was about twice as low in Tris buffer, around the neutral pH. The difference between the two types of buffer is attributed to their different ionic composition. High interfacial concentration in phosphate buffer is especially linked to the phosphate divalent anions. In the presence of divalent sulphate anions, we measured the same level of interfacial concentration than with phosphate buffer. With the PEI pre-treated membrane, we observed, on the time scale of our experiments (15–20 h), similar adsorbed amounts than on the raw membrane, showing that the PEI layer does not constitute a true barrier to the penetration of lysozyme into the membrane core. However, its presence leads to a slower adsorption rate in a system where convection does not occur through the membrane.     

Advances in Characterisation Methods for Sol-Gel Derived Materials: High Resolution Solid State Nuclear Magnetic Resonance

The objective of this paper is to discuss the recent advances in high resolution solid state Nuclear Magnetic Resonance (NMR) to characterise sol-gel derived materials. The first part will be focused on methods to describe M _i --O--M _j connectivities in sol-gel networks. After a brief review on techniques based on scalar J-coupling, we will focus on the use of ¹⁷O solid state NMR experiments. Then in a second part, techniques to probe through-space interactions in hybrid networks will be described, with a particular emphasis on the use of high resolution ¹H solid state NMR sequences and related two-dimensional homonuclear or heteronuclear correlations.     

Synthesis and characterization of a novel cyclic aluminophosphinate: structure and solid-state NMR study

We present the structure and a multinuclear solid-state NMR study of a new cyclic aluminophosphinate. The crystallographic structure of [Al(2)(HC(6)H(5)PO(2))(2)(C(4)H(9)OH)(8)]Cl(4) (compound 1) was obtained at low temperature (a = 11.830(7) A, b = 14.216(6) A, c = 17.790(6) A, beta = 91.25(4) degrees, monoclinic, P21/c, Z = 2). (13)C IRCP (inversion recovery cross polarization) and NQS (non quaternary suppression) NMR experiments allowed the complete assignment of the quaternary carbon atom of the phenyl ring and the precise determination of the isotropic /(1)J(P-C)/ coupling constant. (31)P CP MAS dynamics was carefully studied by varying the contact time. Dipolar oscillations even at slow MAS were observed. Up to 11 kHz, these oscillations were more pronounced, and the P-H distance was easily extracted. (27)Al NMR quadrupolar parameters for 1 were obtained with very good accuracy, and unusual satellite transition splitting was observed. Furthermore, the isotropic lines of the inner and outer transitions were clearly observable, leading to the unambiguous determination of the quadrupolar parameters.     

Studies on the primary structure of cow kappa-casein. Structural features of para-kappa-casein; N-terminal sequence of kappa-caseinoglycopeptide studied with a sequencer

Several long tryptic peptides obtained from reduced maleylated χ-casein were sequenced: they belonged to the N- and C-terminal (37 residues) moieties of para-χ-casein. Several tryptic peptides could then be joined by chymotryptic overlap peptides. 102 amino acid residues of para-χ-casein were thus placed into two long and four shorter sequences. Some structural results were established with a Sequencer which was also employed for a verification of the N-terminal sequence of the χ-caseinoglycopeptide; a previously described short glycopeptide was found again and was reinvestigated.