The efficiency of Schiff base derived from 4-aminoantipyrine, namely 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene) hydrazinecarbothioamide as a corrosion inhibitor on mild steel in 1.0 M H2SO4 was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PD) and electrochemical frequently modulation (EFM) in addition to the adsorption isotherm, corrosion kinetic parameters and scanning electron microscopy (SEM). The results showed that this inhibitor behaved as a good corrosion inhibitor, even at low concentration, with a mean efficiency of 93% and, also, a reduction of the inhibition efficiency as the solution temperature increases. A polarization technique and EIS were tested for different concentrations and different temperatures to reveal that this compound is adsorbed on the mild steel, therefore blocking the active sites, and the adsorption follows the Langmuir adsorption isotherm model. The excellent inhibition effectiveness of 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene)hydrazinecarbothioamide was also verified by scanning electron microscope (SEM).

Relatively inexpensive, stable Schiff bases, namely 3-((4-hydroxybenzylidene)amino)-2-methylquinazolin-4(3H)-one (BZ3) and 3-((4-(dimethylamino)benzylidene)amino)-2-methylquinazolin-4(3H)-one (BZ4), were employed as highly efficient inhibitors of mild steel corrosion by corrosive acid. The inhibition efficiencies were estimated based on weight loss method. Moreover, scanning electron microscopy was used to investigate the inhibition mechanism. The synthesized Schiff bases were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and micro-elemental analysis. The inhibition efficiency depends on three factors: the amount of nitrogen in the inhibitor, the inhibitor concentration and the inhibitor molecular weight. Inhibition efficiencies of 96 and 92% were achieved with BZ4 and BZ3, respectively, at the maximum tested concentration. Density functional theory calculations of BZ3 and BZ4 were performed to compare the effects of hydroxyl and N,N-dimethylamino substituents on the inhibition efficiency, providing insight for designing new molecular structures that exhibit enhanced inhibition efficiencies.

The photostabilization of polyvinyl chloride (PVC) films by Schiff bases was investigated. Polyvinyl chloride films containing 0.5 wt % Schiff bases were produced using the same casting method as that used for additive-free PVC films from tetrahydrofuran (THF) solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also monitored using THF as a solvent. The quantum yield of chain scission (Φ_cs) for the studied complexes in PVC was estimated to range between 4.72 and 8.99 × 10⁻⁸. According to the experimental results, several mechanisms were suggested, depending on the structure of the additive. Ultra violet (UV) absorption, peroxide decomposition and radical scavenging were suggested as the photostabilizing mechanisms.

Copper oxide nanoparticles (CuO NPs) were synthesised with laser ablation of a copper sheet immersed in deionized water (DW), cetrimonium bromide (CTAB), and sodium dodecyl sulphate (SDS), respectively. The target was irradiated with a pulsed Nd: YAG laser at 1064 nm, 600 mJ, a pulse duration of 10 ns, and a repetition rate of 5 Hz. The CuO NPs colloidal were analyzed using UV–Vis spectroscopy, the Fourier transform infrared (FTIR) spectrometer, zeta potential (ZP), X-ray diffraction (XRD), transmission electron microscope (TEM) and field emission scanning electron microscopy (FESEM). The absorption spectra of CuO NPs colloidal showed peaks at 214, 215 and 220 nm and low-intensity peaks at 645, 650 and 680 nm for SDS, CTAB and DW, respectively. CuO NPs’ colloidal results are (−21.6, 1.2, and 80 mV) for negatively, neutrally, and positively charged SDS, DW, and CTAB, respectively. The XRD pattern of the NPs revealed the presence of CuO phase planes (110) (111), (20-2) and (11-1). The TEM images revealed nearly spherical NPs, with sizes ranging from 10–90, 10–50, and 10–210 nm for CuO NPs mixed with DW, SDS and CTAB, respectively. FESEM images of all the synthesized samples illustrate the formation of spherical nanostructure and large particles are observable. The CuO NPs were tested for antibacterial activity against Streptococcus mutans by using the well diffusion method. In this method, CuO NPs prepared in DW at a concentration of 200 μg/mL showed a greater inhibition zone against Streptococcus mutans.

Trichophyton rubrum (T.rubrum) is a pathogenic dermatophyte that can causes fungal infection in keratinized layer of the human tissues such as skin, hair and nails. This work was carried out to study the antifungal activity of CuO nanoparticles (CuO NPs) on the viability of T.rubrum. CuO NPs have been synthesized by pulsed laser ablation of copper target immersed in liquid media using Q-switched pulsed Nd:YAG laser with 1064 nm. The optical properties and the surface charge of CuO NPs colloidal were characterized using UV–Vis spectrophotometer and Zeta potential techniques. UV–Vis spectrophotometer exhibited two peaks of absorption of CuO NPs colloidal: sharp peak at 200 nm and another peak at 630 nm. Zeta potential technique showed negative charge of CuO NPs colloidal (-28.16 mV). The morphological properties of CuO NPs such as particle size, shape and particle size distribution were characterized using Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM), the shapes were spherical and the particle size distribution was inhomogeneous which ranges between 20 to 180 nm. The synthesized CuO NPs presented suitable fungistatic activity against T.rubrum and its highest growth-inhibitory effectiveness was at high concentration (100 μg/ml) and high exposure time (3 hrs). Moreover, the inhibition rate of T. rubrum progressively increased with increasing CuO NPs concentration and exposure time.