Silver nanoparticles dispersed in polyaniline matrixes coated on titanium substrate as a novel electrode for electro-oxidation of hydrazine

Silver nanoparticles dispersed in polyaniline matrixes coated on titanium substrate, as a novel electrode, was easily synthesized by electro-polymerization of aniline on titanium and then electrodeposited silver nanoparticles on PAni electrode. The electrochemical behavior and electro-catalytic activity of silver nanoparticles/PAni/Ti electrodes were characterized by cyclic voltammetry. The morphology of silver nanoparticles on PAni/Ti electrodes were characterized by scanning electron microscopy and energy-dispersive X-ray techniques, respectively. Results indicated that silver nanoparticles with a diameter of about 40–70 nm were homogeneously dispersed on the surface of polyaniline film. The silver nanoparticles/PAni/Ti electrodes were examined for electro-catalytic activity toward oxidation of hydrazine. The results show that these modified electrodes are highly active for electro-catalytic oxidation of hydrazine.     

Influence of the hard coated B4C particulates on wear resistance of Al–Cu alloys

In the present study, sliding wear tests were carried out on different sizes and volume fractions of coated B₄C particles reinforced 2024 aluminum alloy composites fabricated by a squeeze casting method. Microstructural examination showed that the B₄C distributions were generally homogeneous in the matrix while some particle clusterings were observed at relatively high particle containing composites. As compared to the 2024 Al matrix alloy, the hardness of the composites was found to be greater. It is observed that the wear resistance of the composites was significantly higher than that of the unreinforced aluminum alloy, and increased with increasing B₄C particles content and size. The hard B₄C particles act as a protrusion over the matrix, carries a major portion of the applied load and protect the abrasives from penetration into the specimen surface. Combination of rough and smooth regions is distinguished on the worn surface of the composites. The depth and number of grooves in composites decreased with increasing volume fraction of B₄C particles, and the worn surfaces of composites were relatively smooth.     

On the formulation design and rheological evaluations of pectin-based functional gels

In the current study, formulation design and development of a novel pectin-based functional gel were investigated. Amidated low methoxyl pectin (ALMP), high methoxyl pectin (HMP), sorbitol, inulin, rebaudioside-A, gardenia, phloridzin, quercetin, apple flavor, and calcium chloride (as its dihydrated salt) were selected as general ingredients. Response surface methodology was applied to design different formulations and to investigate on their experimental responses. The oscillatory tests were carried out in 2 stages with ALMP, HMP, sorbitol, and inulin as the variables of the 1st stage and ALMP and calcium chloride as the variables of the 2nd stage. Results of the 1st stage indicated relatively similar behaviors throughout the frequency range applied for all of the samples studied (true gels). However, magnitudes of the 5 rheological parameters of this study (storage modulus, loss modulus, loss tangent, complex modulus, and complex viscosity) were affected by different variables (ALMP, HMP, inulin, and sorbitol concentrations). Experimental results confirmed that sorbitol could be omitted from the formula while inulin and HMP could be used at their highest levels studied. At the 2nd stage, only 2 formulas indicated a strong gel behavior and other formulas showed typical behaviors of weaker gels or those of the concentrated solutions. At the conclusion of this study, a finished gelled product formula was suggested with the application of the best levels of the ingredients. The resultant gel was found to be set rapidly with no syneresis and showed a potential to be considered as a functional gelled dessert.     

Improved physical stability of docosahexaenoic acid and eicosapentaenoic acid encapsulated using nanoliposome containing α‐tocopherol

This study aimed to develop a nanoliposomal formulation containing α‐tocopherol loaded with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and to characterise the formulation by its physical stability. For this purpose, different nanoliposomal formulations with dipalmitoyl phosphocholine were prepared using a modified thin‐film hydration method and evaluated by particle size, polydispersity index (PDI), transmission electron microscopy, differential scanning calorimetry and determining the encapsulation efficiencies of DHA and EPA. A physical stability study was conducted by investigating the change in the vesicle encapsulation efficiency, particle size, PDI and shape when stored at 4, 30 and 40 °C for 3 months. High encapsulation efficiency of DHA and EPA (89.1% ± 0.6% and 81.9% ± 1.4%) and appropriate particle size (82 ± 0.8 nm) were obtained for liposomes composed of α‐tocopherol. The optimum formulation was stable for 90 days when kept at 4 °C. This study demonstrated that α‐tocopherol had a protective effect on the physical stability of the nanoliposomes containing DHA and EPA.     

The release rate and antimicrobial activity of calcium-alginate films containing self-microemulsifying Thymus vulgaris essential oil against Escherichia coli and Staphylococcus aureus

The aim of this study was to fabricate antimicrobial calcium-alginate-based films containing the self-microemulsifying thyme essential oil (TEO) formulations using Tween 80 as the surfactant, and acetic (AA) or propionic (PA) acids as the cosurfactants. A Ca-alginate film containing nano-emulsified TEO as well as a neat Ca-alginate film were considered as the controls. The scanning electron microscopy micrographs showed a highly porous texture for SME films, which resulted in an increase in water vapor permeability and water absorption capacity of these films. The SME films released the TEO completely within 155 min and inhibited the growth of S. aureus and E. coli in in vitro antimicrobial tests. The population of S. aureus and E. coli reduced significantly in ground beef covered with SME films. The results of this study showed that self-microemulsifying TEO films could effectively increase the shelf life of ground beef by controlling its microbial population.     

Effect of stabilizer type on the physicochemical properties of rigid PVC. III

The crystallinity of rigid PVC specimens, stabilized by a tin mercaptide or a lead stabilizer, has been studied. It is found that the crystallinity of rigid PVC is greatly influenced by the type of stabilizer added, and that the response of the PVC toward subsequent UV exposure was also different. The effects of unstable structures and crystallinity, after UV irradiation, on the mechanical properties of rigid PVC have been investigated.