Mohamed Elwathig Saeed Mirghani

The massive and uncontrolled use of petroleum-based plastic food packaging has resulted in serious environmental problems. As a result, the food packaging industry should improve packaging materials based on biodegradable polymers, such as chitosan. Edible food coating maintains and improves the shelf life and condition of packaged foods. Researchers have widely investigated the potential applications of biodegradable natural polymers, such as chitosan, cellulose, starch, whey protein, and gelatin in the food packaging industry. Among the natural biodegradable materials available, chitosan and its derivatives have attracted great interest because they have antimicrobial, antifungal, and metal-chelating properties. They are biodegradable polysaccharides and are non-toxic; therefore, they are considered perfect materials for food coating. Adding other active materials, such as fruit extracts, phenolic compounds, and essential oils, can significantly enhance the antimicrobial and antioxidant capacity of chitosan-based packaging materials. Thus, this article investigates the recent updates in food packaging applications based on chitosan essential oil composites.

Graphene-oxide (GO) is one of the most commonly used carbon nanomaterials in advanced applications such as microwave absorption and EMI shielding, due to various advantages such as ease of synthesis and exfoliation, effective doping capability, and superior composite compatibility. In this study, we used the modified Hummer’s method to synthesize GO by exfoliating graphite powder, and a simple hydrothermal approach was employed for elemental doping and GO reduction. As nitrogen–sulfur (N, S) dual-doping precursors, thiourea and l-cysteine amino acids were utilized. The structural features and microporous network structure of GO aerogel foams were investigated. The microwave absorption capabilities of polyethersulfone-based nanocomposite films incorporating the as-produced nitrogen–sulfur enrich reduced GO (NS-rGO) are also explored. According to the physicochemical characterization, the existence of remarkable structural defects with a porous three-dimensional (3D) network was discovered due to heteroatom insertion and hydrothermal doping. Additionally, the dual-doped sample exhibited high Nitrogen and sulfur content of 8.93% and 13.19%, respectively. While NS-rGO possesses a higher conductivity of 174.7[ ][ ]S compared to 12.65[ ][ ]S for GO. The nanocomposites filled with NS-rGO foams demonstrated a high shielding efficiency (SE) of 45[ ]dB in the X-band with a filler loading of 0.5[ ]wt.%. This high SE arises from dopant heteroatoms and the heterogeneous interface, which induce interface polarization, thereby increasing microwave absorption and dielectric constant. It also results from multi-level reflections caused by the 3D porous structures. These findings offer valuable insights into the functionalization of carbon nanostructures and the development of 3D networks in GO-based functional materials, providing further guidance for engineering high-performance electromagnetic interference shielding materials.

The extraction of oils from Sudanese seeds is of great economic and traditional significance. This study investigated the use of ultrasonic-assisted extraction to extract oils from five different Sudanese seeds: desert date (Balanites aegyptiaca L), baobab (Adansonia digitata), peanut (Arachis hypogaea L.), watermelon (Citrullus lanatus), and roselle (Hibiscus sabdariffa). The extraction process used two organic solvents, n-hexane and n-heptane. The results showed that n-heptane was a more effective solvent for extracting oils from Sudanese seeds than n-hexane. The highest oil yield was obtained from B. aegyptiaca seeds, with a yield of 29%. The optimal seed-to-solvent mass ratio for B. aegyptiaca was 1:6, and the optimal extraction time was 1 hour (60 mins). A thermodynamic study was conducted to validate the experimental results. The larger area in the nonpolar region for n-heptane suggests a higher extraction capacity for the seed oils. These results are consistent with the experimental findings of this study. In conclusion, ultrasonic-assisted extraction is a promising method for extracting oils from Sudanese seeds. N-heptane is a more effective solvent than n-hexane for this purpose, and the optimal seed-to-solvent mass ratio and extraction time are 1:6 and 1 hour (60 mins), respectively. The results of this study could be used to develop new commercial products based on Sudanese seed oils. However, further research is needed to investigate the effects of other factors, such as temperature and pressure, on the extraction of oils from Sudanese seeds.

Due to the increasing demand for electrochemical energy storage, various novel electrode and catalysis materials for supercapacitors and rechargeable batteries have developed over the last decade. The structure and characteristics of these catalyst materials have a major effect on the device's performance. In order to lower the costs associated with electrochemical systems, electrochemical systems, metal-free catalysis materials can be employed. In this study, metal-free catalysts composed of nitrogen (N) and sulfur (S) dual-doped multi-walled carbon nanotubes were synthesized using a straightforward and cost-effective single-step hydrothermal method. Carbon nanotubes served as the carbon source, while l-cysteine amino acid and thiourea acted as doping elements. As a result of the physicochemical characterization, many defects and a porous structure were noted, along with the successful insertion of nitrogen and sulfur into the carbon nanotube was confirmed. According to the cyclic voltammetry tests for the dual-doped samples in alkaline conditions, the D-CNT2 catalyst exhibited onset potentials of -0.30 V higher than the -0.37 V observed for the D-CNT3 catalyst. This indicates enhanced oxygen–reduction reaction due to the synergistic effects of the heteroatoms in the structure and the presence of chemically active sites. Moreover, the outstanding specific capacitance of the D-CNT2 catalyst (214.12 F g^-1 at scanning rates of 1 mV s^-1) reflects the effective porosity of the proposed catalyst. These findings highlight the potential of N/S dual–doped carbon nanotubes for electrocatalytic applications, contributing to efficient energy conversion.

Acacia Seyal gum (ASG), also known as gum Arabic, is an antioxidant-rich soluble fiber. ASG has been reported to have many biological activities, including anticancer, antidiabetic, antiulcer, and immunomodulatory activity. Extraction of bioactive compounds from ASG is commonly performed using conventional extraction methods. However, these techniques have certain limitation in terms of extraction time, energy, and solvent requirements. Ultrasound-assisted extraction (UAE) could be used as an alternative technique to extract bioactive compounds in less time, at low temperature, and with less energy and solvent requirements. In this study, the UAE extraction of ASG was optimized using response surface methodology (RSM). A face-centered central composite design (FCCCD) was used to monitor the effect of different independent factors of ultrasound operation (sonication time, temperature, and solvent ratio) on ASG extraction yield. In addition, screening and characterization of phytochemicals in 60% ethanol ASG extract was carried out using Raman microscopy, Fourier transform infrared spectroscopy (FTIR), and gas chromatography time-of-flight mass spectroscopy (GC-TOFMS) analysis. The results indicated that, under optimal conditions (extraction time 45 min, extraction temperature 40 °C, and solid–liquid ratio of 1:25 g/mL), the yield of ASG was 75.87% ± 0.10. This yield was reasonably close to the predicted yield of 75.39% suggested by the design of experiment. The ANOVA revealed that the model was highly significant due to the low probability value (p < 0.0001). Raman spectrum fingerprint detected polysaccharides, such as galactose and glucose, and protein like lysine and proline, while FTIR spectrum revealed the presence of functional groups peaks value of alkanes, aldehydes, aliphatic amines, and phenol. GC-TOFMS spectroscopic detected the presence of strong d-galactopyranose, carotenoid, and lycopene antioxidant compounds. In conclusion, this study demonstrated that the UAE technique is an efficient method to achieve a high yield of ASG extracts. The selected model is adequate to optimize the extraction of several chemical compounds reported in this study.