Anticorrosion and Antimicrobial Tannic Acid-Functionalized Ti-Metallic Glass Ribbons for Dental Abutment.

In this study, a recently reported Ti-based metallic glass (MG), without any toxic element, but with a significant amount of metalloid (Si-Ge-B, 18 atom %) and minor soft element (Sn, 2 atom %), was produced in ribbon form using conventional single-roller melt-spinning. The produced Ti60Zr20Si8Ge7B3Sn2 ribbons were investigated by differential scanning calorimetry and X-ray diffraction to confirm their amorphous structure, and their corrosion properties were further investigated by open-circuit potential and cyclic polarization tests. The ribbon's surface was functionalized by tannic acid, a natural plant-based polyphenol, to enhance its performance in terms of corrosion prevention and antimicrobial efficacy. These properties can potentially be exploited in the premucosal parts of dental implants (abutments). The Folin and Ciocalteu test was used for the quantification of tannic acid (TA) grafted on the ribbon surface and of its redox activity. Fluorescent microscopy and ζ-potential measurements were used to confirm the presence of TA on the surfaces of the ribbons. The cytocompatibility evaluation (indirect and direct) of TA-functionalized Ti60Zr20Si8Ge7B3Sn2 MG ribbons toward primary human gingival fibroblast demonstrated that no significant differences in cell viability were detected between the functionalized and as-produced (control) MG ribbons. Finally, the antibacterial investigation of TA-functionalized samples against Staphylococcus aureus demonstrated the specimens' antimicrobial properties, shown by scanning electron microscopy images after 24 h, presenting a few single colonies remaining on their surfaces. The thickness of bacterial aggregations (biofilm-like) that were formed on the surface of the as-produced samples reduced from 3.5 to 1.5 µm.

Synthesis, fabrication and characterization of 2-naphthyloxy group-substituted bis(2-pyridylimino)isoindoline and its derivatives as a positive electrode for vanadium redox flow battery applications.

In recent years, tridentate nitrogen donor ligands have played a vital role in inorganic chemistry. The ease of synthesis, readily modifiable structure and high stability of 1,3-bis(2-pyridylimino)isoindole (BPIs) compounds make them suitable candidates for many potential applications. In this study, a 1,3-bis(2-pyridylimino)isoindoline derivative bearing a naphthoxy unit and its palladium complex (PdBPI) were synthesized and characterized by single crystal X-ray diffraction, NMR, FT-IR, UV-Vis, and mass spectroscopic methods. The BPI- or PdBPI-modified pencil graphite electrodes were clarified via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), EDX, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The efficiency of these substances in a vanadium redox flow battery (VRB) system was investigated for the first time. The behaviors of the BPI-modified carbon felt electrode (BPI-CF) and PdBPI-modified carbon felt electrode (PdBPI-CF) were investigated in the redox flow battery (RFB) applications. These modified electrodes were obtained by the electrodeposition method. The respective charge potentials of BPI-CF and PdBPI-CF reached 1.63 V and 1.88 V, respectively. The discharge capacity maxima obtained were ∼301 mA h (1204 mA h L-1) and ∼303 mA h (1212 mA h L-1) for BPI-CF and PdBPI-CF at the VRB system under a charge current density of 4.0 mA cm-2 and discharge current density of 0.4 mA cm-2, respectively.

In-situ synthesis of phthalocyanines on electrospun TiO2 nanofiber by solvothermal process for photocatalytic degradation of methylene blue.

Titanium dioxide/phthalocyanine (TiO2/Pc), TiO2/fluor containing phthalocyanine (TiO2/FPc), and TiO2/fluor containing cobalt phthalocyanine (TiO2/FCoPc) had been successfully fabricated by a simple combination of phthalocyanines obtained by in-situ synthesis on the surface of TiO2 nanofibers prepared by electrospinning. Scanning electron microscopy micrographs and X-ray diffraction analysis indicated that the phthalocyanines uniformly immobilized on the surface of TiO2 nanofibers. Photocatalytic activity of TiO2, TiO2/Pc, TiO2/FPc, TiO2/FCoPc nanofibers for methylene blue in water was comparatively investigated firstly by ultraviolet-visible absorption measurements with time, and kinetic parameters were calculated. Results indicated that the obtained TiO2/Pc, TiO2/ FPc and TiO2/FCoPc exhibited high photocatalytic activity for the degradation of methylene blue and TiO2/FCoPc was found the best. It showed similar or higher activities than related studies and can be suggested as a promising candidate for environmental and energy applications.

Hydrogen storage performance of the multi-principal-component CoFeMnTiVZr alloy in electrochemical and gas-solid reactions.

The single-phase multi-principal-component CoFeMnTiVZr alloy was obtained by rapid solidification and examined by a combination of electrochemical methods and gas-solid reactions. X-ray diffraction and high-resolution transmission electron microscopy analyses reveal a hexagonal Laves-phase structure (type C14). Cyclic voltammetry and electrochemical impedance spectroscopy investigations in the hydrogen absorption/desorption region give insight into the absorption/desorption kinetics and the change in the desorption charge in terms of the applied potential. The thickness of the hydrogen absorption layer obtained by the electrochemical reaction is estimated by high-resolution transmission electron microscopy. The electrochemical hydrogen storage capacity for a given applied voltage is calculated from a series of chronoamperometry and cyclic voltammetry measurements. The selected alloy exhibits good stability for reversible hydrogen absorption and demonstrates a maximum hydrogen capacity of ∼1.9 wt% at room temperature. The amount of hydrogen absorbed in the gas-solid reaction reaches 1.7 wt% at 298 K and 5 MPa, evidencing a good correlation with the electrochemical results.

A multifunctional long-term release system for treatment of hypothyroidism.

Hypothyroidism is an autoimmune disease associated with underactive thyroid gland. In this study, a dual effect polymeric system was designed to release Cepharanthine (CEP) to block T cell activation and Selenium (Se) to decrease the anti-thyroid peroxidase (TPOAb) concentration in order to treat hypothyroidism. For this purpose, poly(ethylene-vinyl acetate) (PEVA) and polyethylene glycol (PEG) nanoparticles (NPs) including CEP were synthesized by emulsion solvent evaporation method and they were loaded to polyurethane (PU)/PEG-PUSe-PEG block copolymer blends which were fabricated by particulate leaching technique as porous sponges. Fourier-Transform Infrared (FTIR), Raman, and Nuclear Magnetic Resonance (NMR) analysis showed successful synthesis of PEG-PUSe-PEG block copolymer. A long-term zero-order release profile was obtained for CEP. Se release rate from matrices showed an oxidative stress-mediated release which can be used to adjust Se amount. According to MTS results conducted by NIH 3T3 fibroblasts, both NPs and matrices have no adverse effect on cell viability. Fluorescence microscopy and SEM images confirm the MTS results. The dual release system has potential to be effectively used in long-term treatment of hypothyroidism by addressing both auto-immune response and hormone regulation.

A Novel Carbon Nanofiber Precursor: Poly(acrylonitrile-co-vinylacetate-co-itaconic acid) Terpolymer.

This study aimed to produce poly(acrylonitrile-co-vinylacetate-co-itaconic acid) (poly(AN-co-VAc-co-IA)) terpolymer as a carbon nanofiber precursor. In this respect, terpolymer samples with different IA amounts were synthesized by free radical polymerization. Produced terpolymer samples were electrospun in order to obtain nanofibers which were then converted to carbon nanofibers. Obtained electrospun nanofibers were oxidized at different temperatures between 200-325 °C. After the oxidation process, carbonization process was applied at 1100 °C in the presence of N2. Viscosity and molecular weight distribution of produced samples were measured with ubbelohde viscosimeter and gel permeation chromatography (GPC), respectively. Thermal features of the ter-polymer samples were analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Spectroscopic characterization of terpolymer samples, oxidized and carbonized nanofibers were performed by Fourier transform infrared-attenuated total reflectance (FTIR-ATR). Original electrospun nanofibers, oxidized and carbonized nanofibers were investigated morphologically by scanning electron microscope (SEM). Inclusion of IA had considerable effect on terpolymer properties and electrospun nanofibers. Moreover, it was proven that oxidation temperature was a crucial parameter for carbon nanofiber production from terpolymer. Both morphology and color of the produced nanofiber mats changed when carbonization process was accomplished. It was observed that poly(AN-co-VAc-co-IA) terpolymer has lower initiation temperature when compared to poly(AN-co-VAc) and poly(AN-co-IA) copolymers, giving the opportunity to obtain carbon nanofibers easier, and poly(AN-co-VAc-co-IA) terpolymer can be used as an effective precursor for carbon nanofiber production.