Metallic Glass Films with Nanostructured Periodic Density Fluctuations Supported on Si/SiO2 as an Efficient Hydrogen Sorber.

Nanostructured metallic glass films (NMGF) can exhibit surface and intrinsic effects that give rise to unique physical and chemical properties. Here, a facile synthesis and electrochemical, structural, and morphologic characterization of Pd-Au-Si based MGs of approximately 50 nm thickness supported on Si/SiO2 is reported. Impressively, the maximum total hydrogen charge stored in the Pd-Au-Si nanofilm is equal to that in polycrystalline Pd films with 1 μm thickness in 0.1 m H2 SO4 electrolyte. The same NMGF has a volumetric desorption charge that is more than eight times and 25 % higher than that of polycrystalline PdNF and Pd-Cu-Si NMGF with the same thickness supported on Si/SiO2 , respectively. A significant number of nanovoids originating from PdHx crystals, and an increase in the average interatomic spacing is detected in Pd-Au-Si NMGF by high-resolution TEM. Such a high amount of hydrogen sorption is linked to the unique density fluctuations without any chemical segregation exclusively observed for this NMGF

Potentiometric and conductometric measurements of dicarboxylic acids in non-aqueous solvents

The potentiometric and conductometric measurements have been reported for the titration of aliphatic and aromatic acids in methanol, 1-propanol, pyridine, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK). Good analytical results were obtained by using tetrabutylammonium hydroxide (TBAH) as a standard titrant. A linear relationship has been found between pK(a) values in water and half neutralization potential (HNP) values measured by potentiometric titration of dicarboxylic acids in the solvents such as methanol, 1-propanol, pyridine, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK). It has been shown that equivalent conductivities of dicarboxylic acids resulted in a decrease with increase in the pK(a) values in the same solvents

Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO): a spectroscopic and electrochemical study

In this study, a precursor for carbon nanofibers (CNF) was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO) are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte

FABRICATION OF POLY(ACRYLONITRILE-CO-VINYL ACETATE)-POLY(N-METHYL PYRROLE) COMPOSITE NANOFIBERS

Chemical oxidative polymerization of N-Methyl Pyrrole (NMPy) by cerium(IV) on Poly(Acrylonitrile-co-Vinyl Acetate) matrix in N,N-dimethylformamide (DMF) was performed. Electrospinning technique was used for the preparation of P(AN-co-VAc) solutions with uniformly distributed Poly(N-Methyl Pyrrole) (PNMPy) nanoparticles. In the presence of PNMPy, a new absorption band appeared at 1312 cm -1 which corresponds to CH in plane vibration peak. The dielectric properties of nanofiber composites were evaluated on the basis of the complex permittivity. The SEM and AFM images of composite nanofibers showed that the PNMPy nanoparticles with the dimensions of 20-40 nm were distributed homogeneously

Electrospun nanofibers of poly (acrylonitrile-co-itaconic acid)/silver and polyacrylonitrile/silver: In situ preparation, characterization, and antimicrobial activity

© The Author(s) 2019.In this study, it was aimed to prepare silver nanoparticles by reduction of silver salt (AgNO3) in situ by means of only synthesized polyacrylonitrile (PAN) and poly(acrylonitrile-co-itaconic acid) (P(AN-co-IA)) polymers, and N,N dimethylformamide (DMF). Thereafter, PAN/Ag and P(AN-co-IA)/Ag nanofibers were prepared via electrospinning. Spectroscopic and morphologic characterizations, electrical and thermal features, and antimicrobial activities of the prepared nanofibers against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans were carried out in detail. It was observed that P(AN-co-IA) was much more effective than PAN on the reduction of AgNO3 and formation of silver nanoparticles. Silver nanoparticles and also itaconic acid contributed to decrease the cyclization temperature of PAN by generating sharp exothermic peaks. In addition, electrical conductivity of the nanofibers increased dramatically from E−13 to E−4 related to the presence of silver nanoparticles. Furthermore, incorporation of silver nanoparticles to the nanofiber membranes let bactericidal/fungicidal activities, which started at 6–24 h and continued for up to 168 h, against S. aureus, E. coli, P. aeruginosa, and C. albicans. The prepared silver containing nanofibers can be regarded as good candidates for potential use in the biomedical and pharmaceutical applications

Silver sulfadiazine Loaded Poly (epsilon-Caprolactone)/Poly (Ethylene Oxide) Composite Nanofibers for Topical Drug Delivery

In this study, silver sulfadiazine (SSD) loaded Poly (epsilon-caprolactone)/Poly (ethylene oxide) (PCL/PEO) nanofiber patches were prepared via electrospinning method for topical drug delivery applications. SSD was loaded for the first time into PCL/PEO nanofibers. Nanofiber patches were characterized by Attenuated Total Reflectance Infrared Spectroscopy (FTIR-ATR) to check the presence of chemical bonding between SSD and polymer matrix. The surface morphology of the nanofibers was observed by Scanning Electron Microscopy (SEM). SEM images showed that uniform and smooth composite nanofibers were obtained. The diameter of the nanofibers decreased with the addition of SSD. X-Ray Diffraction (XRD) analysis was carried out to examine the crystallinity of composite nanofiber patches. Energy dispersive spectroscopy (EDS) analysis was performed to confirm Ag and S contents in the SSD loaded composite nanofibers and EDS Mapping was used to show the homogeneous distribution of SSD in the fiber structure. In order to investigate the release and solubility properties of SSD, an unused buffer solution; Water/Propylene Glycol/Phosphoric Acid (82:16:2) was prepared. The release of SSD was performed in this buffer and the release amount of SSD was calculated by UV-Visible Spectrophotometer. Thereby, SSD containing PCL/PEO composite nanofiber carriers were electrospun to achieve the enhancement in solubility, effective drug release and efficient drug loading of SSD. All experimental studies demonstrated that SSD loaded PCL/PEO composite nanofibers have great potential to be used in topical drug delivery applications