Vocalization frequency as a prognostic marker of language development following early cochlear implantation.

Despite their potential significance for later linguistic outcomes, early aspects of vocalization had been seriously undervalued in the past, and thus, minimally investigated until relatively recently. The present article sets out to critically examine existing evidence to: i) ascertain whether vocalization frequency (volubility) posits a plausible marker of cochlear implantation success in infancy, and ii) determine the clinical usefulness of post-implementation vocalization frequency data in predicting later language development. Only recent peer-reviewed articles with substantial impact on vocalization growth during the first year of life, examining sound production characteristics of normally hearing (NH) and hearing impaired infants fitted with cochlear implantation (CI) were mentioned. Recorded differences in linguistic performance among NH and CI infants are typically attributed to auditory deprivation. Infants who have undergone late CI, produce fewer syllables (low volubility) and exhibit late-onset babbling, especially those who received their CIs at the age of 12 months or thereafter. Contrarily, early recipients (before the 12-month of age) exhibit higher volubility (more vocalizations), triggered from CI-initiated auditory feedback. In other words, early CI provides infants with early auditory access to speech sounds, leading to advanced forms of babbling and increased post-implementation vocalization frequency. Current findings suggest vocalization frequency as a plausible criterion of the success of early CI. It is argued that vocalization frequency predicts language development and affects habilitation therapy.

Biodegradation and toxicity of emerging contaminants: Isolation of an exopolysaccharide-producing Sphingomonas sp. for ionic liquids bioremediation.

Ionic liquids (ILs) have been characterized as contaminants of emerging concern (CEC) that often resist biodegradation and impose toxicity upon environmental release. Sphingomonas sp. MKIV has been isolated as an extreme microorganism capable for biodegradation of major classes of ILs. Six imidazolium-, pyridinium- and ammonium-based ILs (pyridinium trifluoromethanesulfonate [Py][CF3SO3], 1-(4-pyridyl)pyridinium chloride [1-4PPy][Cl], 1-butyl-3-methylimidazolium bromide [BMIM][Br], 1-butyl-3-methylimidazolium methanesulfonate [BMIM][MeSO4], tetrabutylammonium iodide [n-Bu4N][I] and tetrabutylammonium hexafluorophosphate [n-Bu4N][PF6]) were used for microbial growth. The strain achieved 91% and 87% removal efficiency for cultures supplemented with 100 mg L-1 of [BMIM][MeSO4] and [n-Bu4N][I] respectively. The metabolic activity of MKIV was inhibited following preliminary stages of cultures conducted using [BMIM][MeSO4], [BMIM][Br], [Py][CF3SO3] and [n-Bu4N][PF6], indicating potential accumulation of inhibitory metabolites. Thus, a comprehensive toxicological study of the six ILs on Aliivibrio fischeri, Daphnia magna and Raphidocelis subcapitata was conducted demonstrating that the compounds impose moderate and low toxicity. The end-products from [BMIM][MeSO4] and [n-Bu4N][I] biodegradation were assessed using Aliivibrio fischeri, exhibiting increased environmental impact of the latter following biotreatment. MKIV produced 19.29 g L-1 of biopolymer, comprising mainly glucose and galacturonic acid, from 25 g L-1 of glucose indicating high industrial significance for bioremediation and exopolysaccharide production.

Amphiphilic Polymer Conetworks Based on End-Linked "Core-First" Star Block Copolymers: Structure Formation with Long-Range Order.

Amphiphilic polymer conetworks are cross-linked polymers that swell both in water and in organic solvents and can phase separate on the nanoscale in the bulk or in selective solvents. To date, however, this phase separation has only been reported with short-range order, characterized by disordered morphologies. We now report the first example of amphiphilic polymer conetworks, based on end-linked "core-first" star block copolymers, that form a lamellar phase with long-range order. These mesoscopically ordered systems can be produced in a simple fashion and exhibit significantly improved mechanical properties.

Heterogeneity in nanocomposite hydrogels from poly(ethylene oxide) cross-linked with silicate nanoparticles.

We investigate the influence of ionic strength on the structural heterogeneity and viscoelastic properties of nanocomposite hydrogels. We use small-angle scattering and rheology to monitor structural changes as a function of ionic strength. Increasing ionic strength makes the nanocomposite gels macroscopically heterogeneous, stiffer and more turbid. At high shear rates, nanometre structures rearrange within aggregates and orient in the flow direction. The changing structural properties that develop with ionic strength are due to increased heterogeneity of nanoparticle distribution and polymer-nanoparticle interactions as well as to the formation of PEO [poly(ethylene oxide)] aggregates interacting with sodium cations, which reinforce the overall hydrogel network.

Synthesis and characterization of anionic amphiphilic model conetworks of 2-butyl-1-octyl-methacrylate and methacrylic acid: effects of polymer composition and architecture.

Seven amphiphilic conetworks of methacrylic acid (MAA) and a new hydrophobic monomer, 2-butyl-1-octyl-methacrylate (BOMA), were synthesized using group transfer polymerization. The MAA units were introduced via the polymerization of tetrahydropyranyl methacrylate (THPMA) followed by the removal of the protecting tetrahydropyranyl group by acid hydrolysis after network formation. Both THPMA and BOMA were in-house synthesized. Ethylene glycol dimethacrylate (EGDMA) was used as the cross-linker. Six of the conetworks were model conetworks, containing copolymer chains between cross-links of precise molecular weight and composition. The prepared conetwork series covered a wide range of compositions and architectures. In particular, the MAA content was varied from 67 to 94 mol %, and three different conetwork architectures were constructed: ABA triblock copolymer-based, statistical copolymer-based, and randomly cross-linked. The linear conetwork precursors were analyzed by gel permeation chromatography and 1H NMR spectroscopy in terms of their molecular weight and composition, both of which were found to be close to the theoretically calculated values. The degrees of swelling (DS) of all the amphiphilic conetworks were measured in water and in THF over the whole range of ionization of the MAA units. The DSs in water increased with the degree of ionization (DI) and the content of the hydrophilic MAA units in the conetwork, while the DSs in THF increased with the degree of polymerization of the chains between the cross-links and by reducing the DI of the MAA units. Finally, the nanophase behavior of the conetworks was probed using small-angle neutron scattering and atomic force microscopy.

Structural effects of crosslinking a biopolymer hydrogel derived from marine mussel adhesive protein.

In an effort to explore new biocompatible substrates for biomedical technologies, we present a structural study on a crosslinked gelatinous protein extracted from marine mussels. Prior studies have shown the importance of iron in protein crosslinking and mussel adhesive formation. Here, the structure and properties of an extracted material were examined both before and after crosslinking with iron. The structures of these protein hydrogels were studied by SEM, SANS, and SAXS. Viscoelasticity was tested by rheological means. The starting gel was found to have a heterogeneous porous structure on a micrometer scale and, surprisingly, a regular structure on the micron to nanometer scale. However disorder, or "no periodic structure", was deduced from scattering on nanometer length scales at very high q. Crosslinking with iron condensed the structure on a micrometer level. On nanometer length scales at high q, small angle neutron scattering showed no significant differences between the samples, possibly due to strong heterogeneity. X-ray scattering also confirmed the absence of any defined periodic structure. Partial crosslinking transformed the viscoelastic starting gel into one with more rigid and elastic properties.

Supramolecular structures in nanocomposite multilayered films.

We investigate the multilayered structures of poly(ethylene)oxide/montmorillonite nanocomposite films made from solution. The shear orientation of a polymer-clay network in solution combined with simultaneous solvent evaporation leads to supramolecular multilayer formation in the film. The resulting films have highly ordered structures with sheet-like multilayers on the micrometer length scale. The polymer covered clay platelets were found to orient in interconnected blob-like chains and layers on the nanometer length scale. Inside the blobs, scattering experiments indicate the polymer covered and stacked clay platelets oriented in the plane of the film. The polymer is found to be partially crystalline although this is not visible by optical microscopy. Atomic force microscopy suggests that the excess polymer, which is not directly adsorbed to the clay, is wrapped around the stacked platelets building blobs and the polymer also interconnects the polymer-clay layers. Overall our results suggest the re-intercalation of clay platelets in films made from exfoliated polymer-clay solutions as well as the supramolecular order and hierarchical structuring on the nanometer, via micrometer to the centimeter length scale.

Cationic double-hydrophilic model networks: synthesis, characterization, modeling and protein adsorption studies.

Group transfer polymerization (GTP) was used for the preparation of eight networks based on two hydrophilic monomers, 2-(dimethylamino)ethyl methacrylate (DMAEMA) and poly(ethylene glycol) methacrylate (PEGMA). Ethylene glycol dimethacrylate (EGDMA) served as the cross-linker, whereas 1,4-bis(methoxytrimethylsiloxymethylene)cyclohexane (MTSMC) was used as a bifunctional initiator. Seven of the networks had linear segments of accurate molecular weight between the cross-links, i.e., they were model networks, whereas the eighth was an equimolar randomly cross-linked network. Five of the seven model networks were based on ABA triblock copolymers with PEGMA midblocks and DMAEMA endblocks, in which the DMAEMA/PEGMA ratio was varied. The remaining two model networks were equimolar isomers, the one based on BAB triblocks (with a DMAEMA midblock) and the other based on the statistical copolymer. The degrees of swelling of all of the networks were measured as a function of pH and were found to increase below pH 7. The degrees of swelling at low pH values increased with the percentage of the DMAEMA monomer, which is ionized under these conditions. These swelling results were confirmed qualitatively by theoretical calculations. Finally, the pH-dependence of the adsorption of the proteins pepsin, bovine serum albumin, and lysozyme onto one of the model networks was studied.