Collagen-Carboxymethylcellulose Biocomposite Wound-Dressings with Antimicrobial Activity.

Microbial infections associated with skin diseases are frequently investigated since they impact on the progress of pathology and healing. The present work proposes the development of freeze-dried, glutaraldehyde cross-linked, and non-cross-linked biocomposite dressings with a porous structure, which may assist the reepithelization process through the presence of collagen and carboxymethylcellulose, along with a therapeutic antimicrobial effect, due to silver nanoparticles (AgNPs) addition. Phisyco-chemical characterization revealed the porous morphology of the obtained freeze-dried composites, the presence of high crystalline silver nanoparticles with truncated triangular and polyhedral morphologies, as well as the characteristic absorption bands of collagen, silver, and carboxymethylcellulose. In vitro tests also assessed the stability, functionality, and the degradability rate of the obtained wound-dressings. Antimicrobial assay performed on Gram-negative (Escherichia coli), Gram-positive (Staphyloccocus aureus) bacteria, and yeast (Candida albicans) models demonstrated that composite wound dressings based on collagen, carboxymethylcellulose, and AgNPs are suitable for skin lesions because they prevent the risk of infection and have prospective wound healing capacity. Moreover, the cell toxicity studies proved that the obtained materials can be used in long time treatments, with no cytotoxic effects.

Mixed modeling for irregularly sampled and correlated functional data: Speech science applications.

The speech sciences often employ complex experimental designs requiring models with multiple covariates and crossed random effects. For curve-like data such as time-varying signals, single-time-point feature extraction is commonly used as data reduction technique to make the data amenable to statistical hypothesis testing, thereby discarding a wealth of information. The present paper discusses the application of functional linear mixed models, a functional analogue to linear mixed models. This type of model allows for the holistic evaluation of curve dynamics for data with complex correlation structures due to repeated measures on subjects and stimulus items. The nonparametric, spline-based estimation technique allows for correlated functional data to be observed irregularly, or even sparsely. This means that information on variation in the temporal domain is preserved. Functional principal component analysis is used for parsimonious data representation and variance decomposition. The basic functionality and usage of the model is illustrated based on several case studies with different data types and experimental designs. The statistical method is broadly applicable to any types of data that consist of groups of curves, whether they are articulatory or acoustic time series data, or generally any types of data suitably modeled based on penalized splines.

The difficulty of articulatory complexity.

In our commentary, we offer some support for the view that frequency rather than a language-independent definition of complexity is a main factor determining speech production in healthy adults. We further discuss the limits of defining articulatory complexity based on transcription data. If we want to gauge the impact of substantive constraints on speech production, context-specific production dynamics should be considered, as has been underscored by articulatory-acoustic work on speech errors.

Applications and toxicity of silver nanoparticles: a recent review.

Silver nanoparticles (AgNPs) exhibit a consistent amount of flexible properties which endorse them for a larger spectrum of applications in biomedicine and related fields. Over the years, silver nanoparticles have been subjected to numerous in vitro and in vivo tests to provide information about their toxic behavior towards living tissues and organisms. Researchers showed that AgNPs have high antimicrobial efficacy against many bacteria species including Escherichia coli, Neisseria gonorrhea, Chlamydia trachomatis and also viruses. Due to their novel properties, the incorporation of silver nanoparticles into different materials like textile fibers and wound dressings can extend their utility on the biomedical field while inhibiting infections and biofilm development. Among the noble metal nanoparticles, AgNPs present a series of features like simple synthesis routes, adequate and tunable morphology, and high surface to volume ratio, intracellular delivery system, a large plasmon field area recommending them as ideal biosensors, catalysts or photo-controlled delivery systems. In bioengineering, silver nanoparticles are considered potentially ideal gene delivery systems for tissue regeneration. The remote triggered detection and release of bioactive compounds of silver nanoparticles has proved their relevance also in forensic sciences. The authors report an up to date review related to the toxicity of AgNPs and their applications in antimicrobial activity and biosensors for gene therapy.

Voice onset time in consonant cluster errors: can phonetic accommodation differentiate cognitive from motor errors?

PURPOSE: Phonetic accommodation in speech errors has traditionally been used to identify the processing level at which an error has occurred. Recent studies have challenged the view that noncanonical productions may solely be due to phonetic, not phonological, processing irregularities, as previously assumed. The authors of the present study investigated the relationship between phonological and phonetic planning processes on the basis of voice onset time (VOT) behavior in consonant cluster errors. METHOD: Acoustic data from 22 German speakers were recorded while eliciting errors on sibilant-stop clusters. Analyses consider VOT duration as well as intensity and spectral properties of the sibilant. RESULTS: Of all incorrect responses, 28% failed to show accommodation. Sibilant intensity and spectral properties differed from correct responses irrespective of whether VOT was accommodated. CONCLUSIONS: The data overall do not allow using (a lack of) accommodation as a diagnostic as to the processing level at which an error has occurred. The data support speech production models that allow for an integrated view of phonological and phonetic processing.

Temporal organization of complex onsets and codas in American English: testing the predictions of a gestural coupling model.

This study systematically investigates the temporal organization of American English onset and coda consonant clusters on the basis of kinematic data. Results from seven speakers suggest that consonants in complex onsets are organized globally with respect to the following vowel, while consonants in complex codas are organized locally relative to the preceding vowel. These results support the competitive coupling model hypothesized for complex onsets, a model according to which consonant gestures in onsets are each coupled in-phase to the vowel, and antiphase with each other. The results are overall also consistent with the noncompetitive coupling relations assumed for codas, by which only the first consonant in a cluster is coupled antiphase with the vowel, and any subsequent consonants are coupled antiphase to each other. However, our data also show that the segmental composition of the cluster affects the timing relationship in codas, particularly/lC/coda clusters pattern differently from other clusters and do not adhere to the predicted timing relations. The data contribute to our understanding of the interaction of linguistic structure and motor control of the articulators in speech production.

Acoustic consequences of articulatory variability during productions of /t/ and /k/ and its implications for speech error research.

An increasing number of studies has linked certain types of articulatory or acoustic variability with speech errors, but no study has yet examined the relationship between such articulatory variability and acoustics. The present study aims to evaluate the acoustic properties of articulatorily errorful /k/ and /t/ stimuli to determine whether these errors are consistently reflected in the acoustics. The most frequent error observed in the articulatory data is the production of /k/ and /t/ with simultaneous tongue tip and tongue dorsum constrictions. Spectral analysis of these stimuli's bursts shows that /k/ and /t/ are differently affected by such co-production errors: co-production of tongue tip and tongue dorsum during intended /k/ results in typical /k/ spectra (and hence in tokens robustly classified as /k/), while co-productions during intended /t/ result in spectra with roughly equal prominence at both the mid-frequency (/k/-like) and high-frequency (/t/-like) ranges (and hence in tokens ambiguous between /k/ and /t/). This outcome is not due to an articulatory timing difference, but to tongue dorsum constriction having an overall greater effect on the acoustic than a tongue tip constriction when the two are co-produced.