Elastic response of Carbon Black reinforced polyester based composites using micromechanical models: Role of interphase

Carbon-based reinforcements have been widely reported in improving mechanical properties of polymers. However, still few studies exist on the incorporation of the interphase as a result of the interfacial interactions into analytical prediction tools. To better understand the effect of interfacial interphase, this study compares and correlates the experimental mechanical response of polyester based composites filled with carbon black (CB) with the elastic behavior obtained from the micromechanical models. Mold cast composites of polyester reinforced with 0 wt%–10 wt% of CB were fabricated. To determine the length of cooperative rearranging region (CRR) as a measure of the interphase, thermal studies focusing on the variations in the specific heat capacity or the relaxation strength of the composites around the glass transition temperature ( Tg) range were performed using a thermodynamical model. Micromechanical models such as the Halpin-Tsai and Tandon-Weng were used to determine the Young’s modulus with respect to the CB wt% and diameter as well as the interphase thickness and modulus. The results exhibited the sensitivity of the models to the existence of the interphase as a secondary mechanism, which was correlated to the cross-link density and interfacial bonding. The impact results showed the decrease in the impact resistance upon the addition of higher filler loadings ascribed to the destroyed bonding at the interface and CBs agglomeration confirmed by morphological studies. The research results can be further utilized in the explanation of the changes in the elastic response of carbon-based reinforced thermosetting composites emphasizing the key role of interphase.

Aging Brain and Hearing: A Mini-Review

Brain reserve is a topic of great interest to researchers in aging medicine field. Some individuals retain well-preserved cognitive function until they fulfill their lives despite significant brain pathology. One concept that explains this paradox is the reserve hypothesis, including brain reserve that assumes a virtual ability to mitigate the effects of neuropathological changes and reduce the effects on clinical symptoms flexibly and efficiently by making complete use of the cognitive and compensatory processes. One of the surrogate measures of reserve capacity is brain volume. Evidence that dementia and hearing loss are interrelated has been steadily accumulating, and age-related hearing loss is one of the most promising modifiable risk factors of dementia. Research focused on the imaging analysis of the aged brain relative to auditory function has been gradually increasing. Several morphological studies have been conducted to understand the relationship between hearing loss and brain volume. In this mini review, we provide a brief overview of the concept of brain reserve, followed by a small review of studies addressing brain morphology and hearing loss/hearing compensation, including the findings obtained from our previous study that hearing loss after middle age could affect hippocampal and primary auditory cortex atrophy.

Enhancement of the Yersinia pestis EV NIIEG Vaccine Srain Immunogenic and Protective Activity under Cultivation with Azoxymer Bromide (Polyoxidonium)

Background. The live-attenuated vaccine based on the Yersinia pestis strain EV line NIIEG is still used in Russia, providing protective efficacy against plague. Nevertheless, there is an urgent need for developing new ways to increase the immunogenicity of the Y. pestis EV NIIEG vaccine strain. In this study, the ability of direct action of immunoadjuvant azoximer bromide (polyoxidonium, PO) on the immunobiological properties of vaccine strain Y. pestis EV NIIEG during cultivation on a dense nutrient medium was evaluated. Materials & Methods. Y.pestis EV NIIEG, cultivated at 28 °С for 48 h on LB agar, Miller pH 7.2 ± 0.1 (Sigma-Aldrich, USA) with the addition of PO and without. MALDI-TOF mass-spectrometry was deployed for the obtainment of mass-spectra of ribosomal proteins from Y. pestis EV NIIEG cells on the MicroflexTM LT mass spectrometer (Bruker Daltonics, Germany). Protective efficacy was evaluated under subcutaneously challenge guinea pigs and mice BALB's with 400 LD50 doses of the Y. pestis 231, Y. pestis P-13268 Vietnam (MLD=5 CFU). Antibody titers to F1 in serum were determined using an ELISA. Results. The addition of the therapeutic concentration of PO in the cultivation medium induced a significant increase in the immunogenicity of Y. pestis EV NIIEG that resulted in enhancement of serum antibody levels against Y. pestis F1 antigen and several times the growth of protective efficacy in the bubonic plague model on two types of experimental animals. ImD50 of the vaccine strain Y. pestis EV NIIEG, cultivated with PO, was significantly (p < 0,05) lower in comparison to ImD50 for Y. pestis EV NIIEG in standard cultivation conditions. One year of storage at a temperature of 4 °С did not alter the protective properties of the vaccine strain Y. pestis EV NIIEG, cultivated with PO. Conclusions. Morphological studies confirmed the absence of influence PO introduction into the cultivation environment on the safety of the vaccine strain. MALDI-TOF MS profile of the Y. pestis EV NIIEG, cultivated with PO, had peaks characteristic features. The mass peak at m/z 3,061 was significantly down-regulated and new mass peaks at m/z 2,759, m/z 3,533 were determined. These changes are accompanied by the increase of Y. pestis EV NIIEG immunogenicity.

Synthesis, Structural, Morphological and I-V Characteristics of Polyaniline-MgCl Composite

Composite of polyaniline-MgCl has been synthesized using oxidative polymerization method. Synthesized samples were characterized for structural analysis using FTIR and XRD. Morphological studies were carried by SEM micrographs. Current-Voltage (I-V) properties are obtained through Kiethly source meter. FTIR spectrum of polyaniline-MgCl composite indicates all the characteristic peaks of polyaniline. X-ray diffraction patterns represented the amorphous nature of polyaniline-MgCl composite. SEM micrographs confirmed the presence of MgCl particles in polyaniline matrix. I-V characteristics have shown the ohmic type behavior of polyaniline and polyaniline-MgCl composite.

Acanthosaura meridiona sp. nov. (Squamata: Agamidae), a new short-horned lizard from southern Thailand

A new short – horned lizard species of the genus Acanthosaura from southern Thailand, is described herein. The species was previously recognised as Acanthosaura crucigera and has been reported to present a wide distribution across mainland south-east Asia. The combination of modern morphological studies of Acanthosaura meridiona sp. nov. allows its separation from closely related species A. crucigera, on the basis of presenting more nuchal scales, more scales between diastema, more scales bordering rostral scales and more midline ventral scales. Mitochondrial DNA analysis also indicated a sister relationship between A. meridiona sp. nov. and A. crucigera with a 100 % probability according to Bayesian and maximum – likelihood analyses. The pairwise distance between A. meridiona sp. nov. and A. crucigera ranges from 9.9 – 11.1 %, while the distance between A. meridiona populations ranges from 0 – 0.9 %. This new discovery contributes to the redescription of the distribution of A. crucigera under Kra Isthmus and its replacement by A. meridiona sp. nov.

Development and Optimization of Acriflavine-Loaded Polycaprolactone Nanoparticles Using Box–Behnken Design for Burn Wound Healing Applications

Nanoparticles are used increasingly for the treatment of different disorders, including burn wounds of the skin, due to their important role in wound healing. In this study, acriflavine-loaded poly (ε-caprolactone) nanoparticles (ACR-PCL-NPs) were prepared using a double-emulsion solvent evaporation method. All the formulations were prepared and optimized by using a Box–Behnken design. Formulations were evaluated for the effect of independent variables, i.e., poly (ε-caprolactone) (PCL) amount (X1), stirring speed of external phase (X2), and polyvinyl alcohol (PVA) concentration (X3), on the formulation-dependent variables (particle size, polydispersity index (PDI), and encapsulation efficiency) of ACR-PCL-NPs. The zeta potential, PDI, particle size, and encapsulation efficiency of optimized ACR-PCL-NPs were found to be −3.98 ± 1.58 mV, 0.270 ± 0.19, 469.2 ± 5.6 nm, and 71.9 ± 5.32%, respectively. The independent variables were found to be in excellent correlation with the dependent variables. The release of acriflavine from optimized ACR-PCL-NPs was in biphasic style with the initial burst release, followed by a slow release for up to 24 h of the in vitro study. Morphological studies of optimized ACR-PCL-NPs revealed the smooth surfaces and spherical shapes of the particles. Thermal and FTIR analyses revealed the drug–polymer compatibility of ACR-PCL-NPs. The drug-treated group showed significant re-epithelialization, as compared to the controlled group.