Amir Naveed

Schiff bases, known for their structural versatility and diverse biological activities, continue to attract significant attention in medicinal chemistry and chemical biology. In the present study, four novel heterocyclic Schiff bases (Sb1–Sb4) were successfully synthesized via condensation reactions and characterized using FTIR, UV–Vis, and NMR spectroscopic techniques. The synthesized compounds exhibited notable antioxidant activity, with Sb2 and Sb4 showing significant DPPH radical scavenging potentials of 79.14% and 75.12%, respectively. DNA-binding studies, carried out through UV–Vis titration with calf thymus DNA, revealed hypochromic and bathochromic shifts, indicating possible intercalative behavior of the compounds. Moreover, the synthesized Schiff bases displayed appreciable antibacterial and antifungal activities against the selected strains, with compound Sb2 emerging as the most potent antibacterial agent among the series. Evaluation of cytotoxicity through the brine shrimp lethality assay confirmed low toxicity (LD50 > 200 µg/mL), suggesting a safe biological profile. Taken together, these findings emphasize the versatile bioactivity of these compounds, integrating antioxidant efficiency, DNA-binding capability, and antimicrobial potential, thereby positioning them as promising scaffolds for future therapeutic development targeting oxidative stress and microbial infections.

Access to uninterrupted power is not a luxury but a basic need. Rural communities living far from the national grid, particularly those in the southern region of Pakistan’s Khyber Pakhtunkhwa province, have limited access to a reliable power supply. In order to provide sustainable electricity, small-scale off-grid renewable energy systems are increasingly used for rural electrification. These systems are commonly known as stand-alone home systems or community micro-grids. This paper proposes an off-grid solar–biogas micro-grid for rural communities in the Lakki Marwat district of Khyber Pakhtunkhwa, Pakistan. The area is mainly dependent upon income from the agricultural and livestock sectors. HOMER was used to simulate the electric power system, while RET-Screen was used to analyze the economics of the system. The optimized system’s results demonstrate that the most economically and technically possible system, which produces 515 kWh and 338.50 m³ biogas daily, is made up of a 30-kW photovoltaic system coupled with a 37-kW biomass hybrid system, a 64-kWh battery storage capacity, and a 20-kW invertor. The system will meet the cooking and power needs of 900 individuals who reside in 100 homes. In addition to household users, the system will provide fixed-priced electricity to productive buildings, and free electricity to community buildings. The system will generate 1300 kg of organic fertilizer each day, which will be sold to local farmers for 50% less than what it would cost on the open market. The proposed approach is techno-economically viable based on the payback period and internal rate of return.

Ceramic membranes are considered superior over their polymeric counterparts for applications at high temperature, pressure, and in aggressive environments with additional advantages of cleaning at high temperature. Preparation of porous ceramic membrane is expensive because the ceramic materials cannot be processed in a liquid state as polymers. Ceramic membrane synthesis involved solid powder preparation, consolidation, suspension formation, calcination, and sintering temperature which makes its synthesis very expensive. Geopolymerization is a heterogeneous reaction of aluminosilicate materials and chemical activators to form a three-dimensional structure having high mechanical strength without sintering. The overall percent energy and cost-saving of geopolymeric membranes were compared with conventional ceramic membranes. Recently, the geopolymerization technique has been used for membrane synthesis to replace conventional ceramic membrane synthesis. The objective of this review article is to discuss the potential opportunities and challenges in the synthesis and application of geopolymeric membranes.

Recently, metal halide perovskite materials for solar cells have gained a wonderful attention from researchers around the world. In this paper, a novel perovskite layer in combination with other layers is numerically investigated to enhance the performance of perovskite-based solar cells (PSCs). General-purpose photovoltaic device model (GPVDM) is used to simulate the proposed structure with Methylammonium Lead Iodide (CH₃NH₃PbI₃), sandwiched between a bi- and tri-layer. The results show enhanced short circuit current density (J _sc ) and power conversion efficiency (PCE) for PSCs. The proposed PSCs show a J_sc of 39.6 mA cm⁻² and PCE 31.4% under standard AM 1.5 G. The bi- and tri-layer sandwiched CH₃NH₃PbI₃ structure is an elegant solution for the realization of high efficiency PSCs.

The impact of different parameters on the compressive strength of geopolymer synthesized from clay and bagasse bottom ash is reported. Geopolymer was synthesized from thermally activated clay and bottom bagasse ash using sodium silicate and sodium hydroxide as activator. The maximum dissolution of alumina and silica from the bagasse ash and clay maintaining different alkali conditions is studied. The resulting geopolymer synthesized under different conditions is studied for compressive strength. Different characterizations of the resulting geopolymer were carried out using different analytical instruments. The results indicated that the dissolution and strength of geopolymer have close relationships with the alkali concentration, solution to solid ratio and curing period. The highest compressive strength of 25 MPa was observed for 8M NaOH, 24 MPa for 0.3 solution to solid ratio, 30 MPa for 60% clay and 30 MPa for 27 days of compressive strength.

In this research work, physical, chemical, morphological, and mechanical behavior as partial replacement of fine aggregate in concrete. Stone dust was acquired from three different sources i.e. Nowshera, Dara, and Besai, while concrete was kept at a ratio of 1:2:4 and water to cement ratio at 0.5 as per ASTM standards for considerable workability. The compressive strength, ultrasonic pulse velocity (UPV), its correlation, density, durability test, x-ray fluorescence (XRF) analysis, and Scanning electron microscopy was carried out. Compressive strength at curing ages of 7, 14, and 28 days with 20%, 30%, and 40% replacement of sand was incorporated in concrete. The results indicated a slight increase in compressive strength at 20% replacement level for the Besai Concrete (BC), Nowshera Concrete (NC), and Dara Concrete (DC). For durability analysis; Rapid Chloride Permeability Test (RCPT) carried out on hardened stone dust-based concrete shows that with the addition of stone dust the voids between fine and coarse aggregates are filled up, less charge will pass, and ultimately durability is increased as per ASTM C 1202. The chemical composition of the stone dust samples, through XRF analysis, indicated that Silica dioxide (SiO2) compounds present in (NC), (DC), and (BC) were 13.34%, 12.339% & 11.593% respectively. The maximum compressive strength development in NC was possibly due to the presence of SiO₂ compound in excess quantity in Nowshera stone dust as compared to other samples tested. Hence it can be recommended that locally available stone dust in Peshawar and its surrounding are suitable for a maximum of 40% replacement level.

Phase change materials (PCMs) are an innovative solution in a thermal energy storage system that can contribute efficiently to the improvement of the energy performance in the building. The phase change is the latent heat of storage materials that can store a large amount of thermal energy in its phase change from solid to liquid and vice versa. The heat storage/release mechanism of PCM is due to its sensitivity to melting/solidifying processes. Optimized ratios of PCM in concrete is essential for effective thermal storage system and strengthen physical characteristic. In this research work, dip coating of phase change materials of melting temperature 17 °C to 50 °C was done for coarse aggregate in the ratios via 25%, 50%, 75%, and 100 v/v% with the cement. The compressive strength of PCM-based coated coarse aggregated 0%, 25%, 50%, 75%, and 100% was investigated after 7, 14, and 28 days’ ages. Encapsulated coarse aggregates (ECA) of different ratios were compared for thermal energy conductance while keeping compressive strength as a key parameter. Temperature differences of 12.35, 15.25, 16.35, 17.5, and 20.3 °C were observed for ECA-100, ECA-75, ECA-50- ECA-25, and NCA, respectively in 12 h. The encapsulated PCM-based coarse aggregate concrete was characterized for physical, thermal conductance, and surface morphology. It was found that ECA-50 offers optimum storage of latent heat and reasonable compressive strength of concrete. However, an adverse impact was found regarding compressive strength as the PCM ratio increases above 50% v/v%, which can be maintained by bonding additives CNTs and GO.

Quest for alternate energy sources is the core of most of the research activities these days. No matter how small or large amount of energy can be produced by utilizing the non-conventional techniques and sources, every bit of innovation can reshape the future of energy. In this work, experimental analysis of the thermoelectric (TE) properties of bulk-graphene in the temperature range of (303 to 363) K is presented. Graphene powder was pressed to form a pellet which was used to fabricate the TE device. The effects of temperature on the Seebeck coefficient, electrical and thermal conductivities, and the dimensionless figure of merit (FOM) were measured. The increasing value of the Seebeck coefficient (thermopower) with temperature is indicant of the metallic behavior. Additionally, the observed thermopower (TEP) is positive, which shows that the majority charge carriers are holes and peaked to a value of 56 μV K⁻¹ at 363 K. The thermopower of the pellet is four times larger than the previously reported values for single layer graphene (SLG) and few layer graphene (FLG). In addition to this, low values of the thermal conductivity were observed for the pellet which is one of the requirements of a good TE material. Besides this, an upward trend is observed with increasing temperature for FOM, which attains a peak value of 0.0016 at 363 K, which is almost ten times that of the previously reported values.

Dewatering of fruit juice through forward osmosis (FO) has attracted great attention in recent years; however, its application for fruit juice concentration through FO is limited due to high fouling rate, low flux, and expensive nature of membranes. Inorganic membranes are expensive due to heat-intensive steps and expensive raw materials that are involved in its synthesis, while geopolymerization technique for inorganic membrane synthesis reduced the cost due to its sintering-free steps and using fly ashes as a source material. In this research work, we report sintering-free economical and eco-friendly geopolymeric membrane in FO pilot-scale plant for orange juice concentration. However, the low flux of geopolymeric membrane was enhanced through coating of graphene oxide (GO) layer for high hydrophilicity. In this work, water flux through GO-based coated and uncoated geopolymeric membrane for concentrating sugar solution through FO was investigated. Prepared GO was coated on geopolymeric substrate through spin technique. The pore size of both geopolymeric substrate and GO was 1.8 and 5 µm, while porosity was 51.09% through the gravimetric method for both active and supportive layer. The orange juice solution was concentrated to 26.1 ± 0.5° and 21.87° Brix from 15.2 ± 0.5° Brix reaching flux of 0.405 and 0.360 kg.m⁻².h⁻¹ at a temperature of 30°C using sodium chloride salt solution (10 M) by coated and uncoated geopolymeric membranes, respectively. This study indicates that GO-based coated geopolymeric substrate is an eco-friendly and cost-effective feasible approach for fruit juice concentration through FO application.

In transformers, in addition to the primary and secondary coils, there are several other important components and accessories in which the insulating material is one of the most critical components of a transformer. Sufficient insulation between different active parts are necessary for safe operation. Adequate insulation, it is not only necessary to insulate the coils from each other, or from the core and tank, but also guarantees the safety of the transformer against accidental surges, but with the growth in size and complexity of power stations, transformer is facing insulation problems. The evaluation of the transformer overload capacities certainly leads to complex variables that affect the operating life of the power and distribution transformer. In this study, the long-life calculation is performed on the basis of two experiments, which are related to the insulation degradation of the mineral oil and cellulose paper such as by adding different types of nano-particles to the mineral oil to enhance the strength of oil, and by changing the loads under different operating conditions to control the deteriorating rate of the insulation to prevent the life of the transformer. The insulation breakdown strength is improved from 37 kV to 71 kV by mixing the semiconductor nanoparticles such as gadolinium-doped ceria (GDC) and cerium dioxide (CeO2) with mineral oil. Moreover, for cellulose paper, thermal degradation rate is kept below its limit by reducing the temperature when controlling the load.