Journal of Applied Sciences and Nanotechnology

The concentration of the polymer solution is one of the most important factors in the formation of fibers in electrospinning technology. Different polymer concentrations of thermoplastic polystyrene are used in this study. At the same time, the other operating parameters of the electrospinning process (such as flow rate, voltage, distance between capillary and collector), the solution parameters (such as conductivity and molecular weight of the solution) and the environmental conditions (such as temperature and humidity) were kept constant. Field emission scanning electron microscopy was used to investigate the morphological changes on the surface of the fibers and to determine the typical fiber diameter. It was found that as the polystyrene concentration was increased from 15% to 30%, the average pore size increased from (0.5µm and 0.44µm) to (2.7µm and 2.6µm). The FT-IR showed the main chemical bonds in the polystyrene membranes and the change in peak intensity by increasing the polymer concentration. The contact angle measurements, which are used to investigate the change in hydrophobic properties, show that the hydrophobicity of the membranes decreases as the water contact angle decreases from 135 to 116 when the polymer concentration is increased from 15% to 30%.

This study analyzes the effects of laser pulse energy set at 700 millijoules per pulse on silver, gold and silver@gold nanoparticles deposited on porous silicon (PS). Our main goal is to determine the optimal conditions by comprehensively evaluating their influence on structural, electrical, morphological and optical properties. In pulsed laser ablation in liquid, a Nd:YAG laser with a pulse width of 10 nanoseconds and a wavelength of 1064 nm is used to produce the nanoparticles. X-ray diffraction (XRD) analysis confirms the crystalline growth of the core-shell nanoparticles with distinct peaks in the data confirming the presence of both Au and Ag nanoparticles. Morphological analysis shows a robust connection between the nanoparticles and the porous silicon layer, indicating structural stability. The UV–vis spectra show a localized surface plasmon resonance band (LSPR) in the range of 412–521 nm. It is noticeable that with increasing gold concentration the two peaks of the LSPR band converge to a single peak. Comparison of the photoluminescence emission spectra of the PS substrate and the NPs/PS shows a clear broadening of the emission band in PS, indicating a high-quality porous silicon structure. The intriguing properties of Ag@Au NPs make them promising for application in gas sensing systems.

Cu2ZnSnS4 (CZTS) is a promising material for use in solar cells. The special properties of this substance include its occurrence on earth, its low cost, its non-toxicity, its high absorption coefficient, its p-type conductivity and its ideal band gap. CZTS has a stannite (ST) and kesterite (KS) crystal structure. Kesterite has excellent thermodynamic stability compared to stannite. Therefore, CZTS is most common in this era. Sputtering, thermal evaporation, pulsed laser deposition, spray pyrolysis, chemical vapor deposition, spin coating, electrodeposition, SILAR, sol-gel, solvothermal and hydrothermal processes are among the various processes used to produce CZTS thin films. The solvothermal and hydrothermal processes are widely used to produce high quality nanocrystals with unique morphology and crystallographic structure and to produce them at low cost. In addition, the solvothermal and hydrothermal processes have been used to fabricate various categories of photovoltaic devices with CZTS, including photoelectrochemical cells, dye-sensitized solar cells, perovskite solar cells, and heterojunction solar cells. In addition, the solvothermal and hydrothermal methods have been used to fabricate other types of photovoltaic devices with CZTS, such as photoelectrochemical cells, dye-sensitized solar cells, perovskite solar cells, and heterojunction solar cells. In addition, it provides an overview of the use of CZTS in photovoltaic applications produced by hydrothermal and solvothermal techniques. The article also addresses the obstacles encountered in the implementation of these applications. Finally, it offers the possibility of finding solutions to these difficulties.

Aqueous solutions with heavy metals such as Cr (VI), Pb, and Cd (II) can have an adverse effect on human health because of their toxicity. As a result, it is important to remove these heavy metals from the aquatic environment to save the human healthy. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and field-emission scanning electron microscopy (FE-SEM) used in this research to characterize cobalt ferrite (CoFe2O4) nanoparticles and confirm the structure of Co-Fe2O4. These particles were used to make porous samples and burned at 1050 °C in mixtures of (0, 3, 5, 7, and 10) wt.% of cobalt ferrite and kaolin with 20 wt.% of charcoal. These samples serve as adsorbents that remove Pb from the wastewater. The highest rates of removal were confirmed using various treatments at (pH 3, 7, and 9). A Williamson-Hall plot was used to determine the crystal size (33) nm. The FT-IR spectra exhibited spinel-ferrite characteristics. Studies using FE-SEM demonstrated that the sample was in Nano crystalline. Using a vibrating sample magnetometer (VSM), different magnetic properties are taken from the hysteresis loops such as saturation magnetization (Ms) and remanence (Mr) and coercivity (Hc). It was found that increasing ferrite content, increased adsorption efficiency.

In this study, we synthesized magnesium oxide (MgO) nano flakes (NFs) through pulsed laser ablation of magnesium ribbons, investigating their potent antibacterial properties for potential biomedical applications. Thorough characterization utilizing advanced analytical techniques verified the phase purity and functionality of the fabricated MgO NFs. Results revealed a distinctive flake-like structure with an average diameter of 100-400 nm and a slender wall thickness of 24 nm. The efficiency of the laser ablation method was validated by EDX imaging, showing high purity in the MgO sample. XRD analysis further confirmed the polycrystalline nature of MgO NFs, with dominant peaks at 2θ values of 38.86°, 59.46°, 62.83°, and 73.87° corresponding to (111), (110), (220), and (311) diffractions, respectively. UV-visible spectroscopy exhibited a broad absorption peak, and Tauc's formula yielded an energy band gap of 5.8 eV. FTIR spectroscopy detected Mg–O–Mg bending vibration, O−H stretching vibration, O=C=O stretching, and O−H bending vibration. Optimized MgO-NFs demonstrated remarkable antibacterial efficacy against both gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) bacteria. Maximum antibacterial activity was observed at a high MgO NFs concentration (200 µg/mL), resulting in 15 mm ±0.5 mm and 16 mm ±0.5 mm inhibition zones for E. coli and S. aureus, respectively. The minimum inhibitory concentration (MIC) for both pathogens was determined to be 25 µg/mL, emphasizing the promising antimicrobial potential of the MgO NFs.

The brittleness and porosity of cement mortar leads to low compressive, flexural, and tensile strengths and poor hardness, making it susceptible to environmental degradation. This study aimed to improve the mechanical and physical properties of cement mortar using a simple and cost-effective approach of impregnating pre-cured hardened mortar with polymers. Three polymers - polyethylene glycol (PEG), polyacrylamide (PAM), and polyvinyl alcohol (PVA) - were used for impregnation. The polymers were blended with a magnetic stirrer and the impregnation was performed via three methods: vacuum, ultrasound, and 24-hour immersion. The results showed significant improvements in mechanical and physical properties. PEG-impregnated samples exhibited the highest compressive strength (24.47 MPa), flexural strength (1.38 MPa), and splitting tensile strength (2.08 MPa) compared to reference samples with 17 MPa, 0.52 MPa, and 1.35 MPa respectively. PAM-impregnated cement mortar displayed the highest hardness value of 81 versus 70.08 for the reference sample. Optimal results were achieved via the vacuum method, with increases in bulk density. The polymer impregnation filled pores and improved bonding, enhancing the mechanical properties of the brittle cement mortar.