Volume 116, Issue 11-12

Wire Arc Additive Manufacturing (WAAM) is a direct energy deposition-based additive manufacturing process that uses an arc welding power source to fabricate large-scale 3D components from wire feedstock. In order to optimize the WAAM process, it is crucial to understand how process variables, such as shielding gas composition, affect build quality. This study investigates the effects of pure Ar, pure CO 2 , and Ar+CO 2 (80:20) shielding gases on single- and multi-layer depositions using a six-axis robotic WAAM system equipped with an automated wire feeder. The objective is to evaluate how these gases influence the bead profile, microstructure, and mechanical properties of WAAM-deposited low-carbon steel. Results show that Ar+CO 2 shielding yields the widest bead profiles with a uniform surface finish, while CO 2 shielding enhances penetration but results in coarser microstructures and lower alloy retention. Ar shielding produces finer grains and the highest hardness, while tensile strength remains comparable under Ar and Ar+CO 2 , with the latter providing higher elongation. Charpy impact tests reveal that Ar-shielded builds have the highest toughness, CO 2 -shielded ones the lowest with brittle features, and Ar+CO 2 -shielded builds exhibit toughness and fracture behavior similar to those under Ar shielding. These findings provide valuable insights for selecting shielding gases to tailor the geometric and mechanical performance of WAAM builds.

Al 2 TiO 5 –mullite material was produced through the sintering process using Algerian natural raw materials. The selected raw materials included kaolin KT (45 wt.%), potassic feldspar (30 wt.%), and quartz (25 wt.%), with TiO 2 nanoparticles added at concentrations of 5 and 10 wt.%. The mixture was milled for 8 h at room temperature in a high-energy planetary ball mill under an argon atmosphere. After milling, the powders were pressed into pellets and then sintered for 2 h at a temperature of 1,200 °C in air. The effect of TiO 2 nanoparticle addition on the physical and structural properties of the porcelain was analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, as well as bulk density and shrinkage measurements. The sintered ceramics primarily showed mullite and quartz. With 5 wt.% TiO 2 , aluminate titanate (Al 2 TiO 5 ) began to form in addition to the existing phases, while rutile was observed as an unreacted phase. Increasing TiO 2 content to 10 wt.% led to a higher volume fraction of Al 2 TiO 5 and a reduction in mullite content. The overall densification of the ceramics improved with the addition of TiO 2 , enhancing physical and microstructural properties.

Agricultural waste contributes to escalating environmental pressures but also represents a valuable, renewable source for sustainable nanomaterial production. In this study, durian seed extract (DurSE), obtained from the often-discarded seeds of Durio zibethinus , was utilized as a natural reducing and capping agent for the green synthesis of multifunctional gold nanoparticles (AuNPs). The biosynthesis process was systematically optimized by varying key parameters, with the most favorable conditions identified as 4 °C reaction temperature, 3 mL extract volume, and 1 mM HAuCl 4 ·3H 2 O concentration. Structural and physicochemical characterizations of the resulting DurSE–AuNPs were performed using Ultraviolet–Visible spectroscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and X-ray diffraction, confirming particle stability, functional group involvement, and crystalline nature. Biocompatibility and therapeutic potential were assessed in-vitro against MCF-7 human breast cancer cells, where the nanoparticles significantly reduced cell viability to 31 % at a concentration of 32 μg mL −1 . Furthermore, the DurSE–AuNPs demonstrated excellent catalytic activity, achieving complete reduction of Methylene Blue and Methyl Orange dyes within 3 min and 15 min, respectively. These results highlight the dual biomedical and environmental potential of agricultural waste-derived nanomaterials, offering a sustainable route for producing high-value, multifunctional nanoparticles.

Aluminum terephthalate metal−organic framework (MIL-53(Al)) was synthesized via the hydrothermal method. The influence of the molar ratio between AlCl 3 and terephthalic acid (TA), reaction temperature, and material-treated temperature was investigated. The resulting MIL-53(Al) synthesized with the AlCl 3 /TA molar ratio of 1:0.5 and the reaction temperature ranging from 120 to 200 °C exhibits high crystallinity. The thermal treatment of as-synthesized MIL-53(Al) at 450 °C for 8 h unblocked the pores via the decomposition of unreacted TA molecules and enlarged the surface area of the material (from 11.4 m 2  g −1 to 121.9 m 2  g −1 ), while increasing Pb(II) removal efficiency. The Pb(II) adsorption on calcined MIL-53(Al) occurs favourably at low temperatures (<40 °C) and is exothermic. The adsorption is favourable according to the Langmuir isotherm, while moderately difficult according to the Freundlich isotherm. The adsorption capacity for Pb(II) calculated from the Langmuir model is 28.09 mg g −1 . The Pb(II) adsorption efficiency of the material increases significantly when pH increases from 2 to 6. The mechanism of the adsorption process is also discussed.

The advancement of nanotechnology has led to the exploration of environmentally sustainable methodologies for nanoparticle synthesis, particularly emphasizing the significance of green chemistry. Among these, the green synthesis of gold nanoparticles (AuNPs) using natural extracts has gained attention with respect to their potential biomedical applications. This study presents a novel method for the green synthesis of AuNPs employing CPH extract, which is sustainable and environmental-friendly. The synthesized CPH–AuNPs exhibited remarkable stability as evident from different characterization techniques, including UV–visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Transmission Electron Microscopy. These analyses revealed that the CPH–AuNPs were predominantly homogeneous, spherical shaped with an average particle size and crystallite size of 16 nm and 17 nm, respectively. UV–Vis spectroscopy confirmed successful synthesis of CPH–AuNPs, with absorption peak stabilizing at 533 nm. TEM technique further confirmed the long–term stability feature of the synthesized nanoparticles. Additionally, the biosafety of CPH–AuNPs assessed using brine shrimp ( Artemia salina ) hatching assay, revealed 47 % hatching rate at the least concentration of 62.5 µg mL −1 , thereby underscoring their high biocompatibility. This research paves the way for the development of novel AuNPs synthesized using isolated polyphenols from CPH extract, with promising implications for their application in the biomedical field.