ABSTRACT
Corrosion is a significant problem and is, to a large extent, responsible for the degradation of metallic parts. In this direction, mesoporous silica particles (MSPs) were synthesized by a sol-gel technique and had an average pore diameter of â¼6.82 nm. The MSPs were loaded with polyethyleneimine (PEI) and epoxy monomers and, after that, carefully mixed into the epoxy matrix to formulate new modified polymeric coatings. The microstructural, compositional, structural, and thermal properties were investigated using various characterizing tools [Transmission electron microscopy, Fourier transform infrared spectroscopy, hermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy]. TGA confirms the loading of mesoporous silica with a corrosion inhibitor, and its estimated loading amount is â¼8%. The electrochemical impedance spectroscopy properties of the reference and modified coated samples confirm the promising anti-corrosive performance of the synthesized polymeric smart coatings. Localized electrochemical tests (scanning vibrating electrode technique and scanning ion-selective electrode technique) evidence the corrosion inhibition ability of the coating, and its self-healing was also observed during 24 h of immersion. The decent anti-corrosion performance of the modified coatings can be credited to the efficient synergistic effect of the PEI and epoxy monomer.
ABSTRACT
Polymeric-based nanocomposite coatings were synthesized by reinforcing epoxy matrix with titanium nanotubes (TNTs) loaded with dodecylamine (DOC). The performance of the developed nanocomposite coatings was investigated in corrosive environments to evaluate their anti-corrosion properties. The SEM/TEM, TGA, and FTIR analysis confirm the loading of the DOC into the TNTs. The UV-Vis spectroscopic analysis confirms the self-release of the inhibitor (DOC) in response to the pH change. The electrochemical impedance spectroscopic (EIS) analysis indicates that the synthesized nanocomposite coatings demonstrate superior anticorrosion properties at pH 2 as compared to pH 5. The improved anticorrosion properties of nanocomposite coatings at pH 2 can be attributed to the more effective release of the DOC from the nanocontainers. The superior performance makes polymeric nanocomposite coatings suitable for many industrial applications.
ABSTRACT
In this work, Al-B4C nanocomposites were produced by microwave sintering and followed by hot extrusion processes. The influence of ceramic reinforcement (B4C) nanoparticles on the physical, microstructural, mechanical, and thermal characteristics of the extruded Al-B4C nanocomposites was investigated. It was observed that the density decreased and porosity increased with an increase in B4C content in aluminum matrix. The porosity of the composites increased whereas density decreased with increasing B4C content. Electron microscopy analysis reveals the uniform distribution of B4C nanoparticles in the Al matrix. Mechanical characterization results revealed that hardness, elastic modulus, compression, and tensile strengths increased whereas ductility decreases with increasing B4C content. Al-1.0 vol. % B4C nanocomposite exhibited best hardness (135.56 Hv), Young's modulus (88.63 GPa), and compression/tensile strength (524.67/194.41 MPa) among the materials investigated. Further, coefficient of thermal expansion (CTE) of composites gradually decreased with an increase in B4C content.
ABSTRACT
BACKGROUND: The objective of this study was to determine the proportion of women who want to know fetal gender on antenatal ultrasonography and the reasons behind this. METHODS: A descriptive, cross-sectional study was carried out between March 10, 2012 and September 10, 2012 at two tertiary care hospitals (Dow University Hospital, Ojha Campus, and Lady Dufferin Hospital) in Karachi. In total, 223 pregnant women who attended the antenatal clinic and gave their consent were included in the study. Information was collected on a predesigned questionnaire. RESULTS: Of the 223 pregnant women, 109 (49.1%) were younger than 25 years. The majority (216, 96.9%) were Muslim, 164 (73.4%) were educated to different levels, 121 (54.3%) spoke Urdu, and 66 (29.6%) were primigravidas. Thirty-four (15.2%) women had a preference for a male child, 24 (10.8%) had a female preference, and 165 (74%) had no preference. Seventy (31.4%) women were interested to know the fetal gender. The association between education and gender preference was found to be statistically significant (P = 0.004) and also that between age and gender preference (P = 0.05), but no relationship was found between gender preference and gender of previous babies (P = 0.317 for males and P = 0.451 for females). Association of ethnicity was also not statistically significant (P = 0.102). CONCLUSION: This study revealed that 31.4% of women were interested in disclosure of gender on prenatal ultrasonography and only15.2% women had a preference for a male child.
