Development and characterization of smart composites reinforced with fibrillated cellulose and nickel-titanium alloy

The current study presents the synergistic effects of fibrillated cellulose (FC) and nickel-titanium (NiTi) alloy on the performance properties of smart composites. Epoxy resin was reinforced with loadings of 1 %, 3 %, and 5 % FC and 3 % NiTi. The composites were produced using the casting method. The morphological properties have been analyzed using scanning electron microscopy (SEM). For mechanical properties, yield strength, modulus of elasticity, hardness, and impact energy were determined. The corrosion rate was determined via electrochemical corrosion testing. The recovery test was used to measure the shape-memory of the composites. The self-healing of the artificial defect in the composites was observed using a thermal camera. The yield strength, modulus of elasticity, hardness, and impact energy of composites reinforced with 5 % FC and 3 % NiTi increased by 168.2 %, 290 %, 33.3 %, and 114.3 %, respectively, compared to pure epoxy resin. There has been a 56.3 % decrease in the corrosion rate. The percentage of composites that returned from the final state to the original state after a deformation was 4 %. Self-healing analysis revealed that the scratch defect in composites was healed after 24 h. It is concluded that smart composites can be used in the aviation and automotive industries.

Preparation and Characterization of Polyvinyl Alcohol (PVA)/Carbonized Waste Rubber Biocomposite Films

The technological properties of composite materials (thermal, strength, rheology, electrical and morphology) are very important parameters for high-performance applications. In this study, we aimed to improve the properties of PVA by using carbon materials obtained by the pyrolysis of waste tires, with the aim of recycling them instead of disposing of them. For this purpose, PVA biocomposite films containing carbonized waste rubber at different rates were prepared. The thermal properties of the prepared biocomposite films were examined via thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) methods. While rheological measurements were carried out with a rheometer, bulk conductivities were measured with a pico-ammeter. In addition, the morphology of biocomposite films was determined via field emission scanning electron microscopy. The nanomechanical properties of biocomposite film was investigated via XPM analyses. According to the rheological measurements and nanoindentation hardness results, it is understood that as the amount of carbonized waste rubber increases, flexibility decreases and harder and brittle structures are observed in biocomposite films. The electrical measurement results showed that electrical conductivity increased as the amount of carbonized waste rubber increased. When all the results obtained were evaluated, it could be concluded that biocomposite films obtained by increasing the electrical conductivity and hardness of PVA can be used in the electronics industry.

Lignocellulosic Bionanomaterials for Biosensor Applications

The rapid population growth, increasing global energy demand, climate change, and excessive use of fossil fuels have adversely affected environmental management and sustainability. Furthermore, the requirements for a safer ecology and environment have necessitated the use of renewable materials, thereby solving the problem of sustainability of resources. In this perspective, lignocellulosic biomass is an attractive natural resource because of its abundance, renewability, recyclability, and low cost. The ever-increasing developments in nanotechnology have opened up new vistas in sensor fabrication such as biosensor design for electronics, communication, automobile, optical products, packaging, textile, biomedical, and tissue engineering. Due to their outstanding properties such as biodegradability, biocompatibility, non-toxicity, improved electrical and thermal conductivity, high physical and mechanical properties, high surface area and catalytic activity, lignocellulosic bionanomaterials including nanocellulose and nanolignin emerge as very promising raw materials to be used in the development of high-impact biosensors. In this article, the use of lignocellulosic bionanomaterials in biosensor applications is reviewed and major challenges and opportunities are identified.

Matrix impact on the mechanical, thermal and electrical properties of microfluidized nanofibrillated cellulose composites

This study reports on the effect of organic polyvinyl alcohol (PVA) and silica matrix on the properties of cellulose-based nanocomposites. Nanofibrillated cellulose was isolated from kraft pulp and treated with Pulpzyme HC 2500 enzyme prior to high-pressure homogenization in order to lower energy consumption. Three nanocomposite films were fabricated via the casting process: nanofibrillated cellulose, nanocellulose-PVA (NC-PVA) and nanocellulose-silica (NC-Si). Chemical characterization and crystallization were determined with FTIR. Thermal stability was investigated with thermogravimetric analysis. Morphological alterations were monitored with scanning electron microscopy. A universal testing machine and dynamic mechanical thermal analysis were used for determination of Young’s and storage moduli. The real and imaginary parts of permittivity and electric modulus were evaluated using an impedance analyzer. Considerable alterations were seen under FTIR. Thermal stability was lower in NC-Si than in NC-PVA due to lower crystallinity. Higher Young’s modulus and storage moduli were observed in NC-PVA than in NC-Si. NC-PVA exhibited a singular relaxation process, while a double relaxation process was seen in NC-Si. Consequently, the nanocomposite film prepared from the organic matrix (NC-PVA) had a mechanical advantage for industrial applications. However, neat NC composite revealed the highest storage modulus and thermal stability.

Low levels of circulating platelet factor 4 (PF4, CXCL4) in subclinically hypothyroid autoimmune thyroiditis

PURPOSE

Chemokines play an important role in the pathogenesis of autoimmune thyroid diseases. Platelet factor 4 (PF4, CXCL4) released from activated platelets is a chemokine. However, its clinical importance in autoimmune thyroiditis remains unknown. This study is intended to determine circulating levels of PF4 levels in patients with autoimmune thyroiditis (AIT).

METHODS

Circulating levels of PF4 were measured in 34 consecutive patients with newly diagnosed AIT and 18 euthyroid controls. Among AIT group, 16 patients were euthyroid and 18 had subclinic hypothyroidism. Controls and individuals with AIT were similar in terms of age.

RESULTS

Serum levels of PF4 were comparable in patients with AIT and in controls. Among patients with AIT, PF4 was significantly lower in those with subclinical hypothyroidism than in euthyroid individuals (p = 0.001). In correlation analysis, PF4 was negatively correlated with TSH (r = -0.663, p = 0.000) and positively correlated with free T4 (r = 0.428, p = 0.012). There was not any significant correlation between PF4 and AbTPO, AbTg.

CONCLUSION

The present study demonstrated for the first time that circulating PF4 levels are decreased in subclinically hypothyroid AIT. This result draws attention to the circulating PF4 levels in subclinically hypothyroid AIT and may shed light on further researches at this topic.