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This study presents a quad-band stub-incorporated split octagonal ring antenna specifically designed for wireless applications that rely on satellite communication. The antenna is fabricated on an FR4 substrate with dimensions of 26×21×1.6 mm³ and its performance is simulated using the CST EM Studio software. The device operates in the frequency range from 2.15 GHz to 6.35 GHz, using stub integration and gap modification to achieve resonant bands. The antenna has resonant frequencies of 2.23 GHz, 3.28 GHz, 4.77 GHz, and 5.89 GHz, with corresponding bandwidths of 153 MHz, 9011 MHz, 7692 MHz, and 6813 MHz, respectively. The parametric analysis optimizes the values of the design parameters, while the experimental validation shows the consistency between the measured and simulated results. The antenna is characterized by a small size, a consistent radiation pattern and a wide range of applications including ISM, WIFI, WLAN, WIMAX, 5G, and C-Band Satellite. The device is capable of operating in two frequency bands and consistently maintains a gain of over 1 dBi across its resonating range.

Water contamination resulting from the presence of organic dye pollutants in the ecosystem is a significant issue in the 21st century, that requires urgent resolution. Utilizing an effective nanocatalyst for the removal of dyes from water is a viable solution to address this problem. In this study, we proposed two distinct approaches for synthesizing δ-MnO2 nanostructures: an environmentally friendly, “green” method (MG) and a “cost-effective” hydrothermal method (MH). The leaf extract of Clinacanthus nutans was used for the preparation of MG, while MnSO4 was used for MH as a reducing agent, along with KMnO4, with the reaction time fixed at 90 °C. X-ray diffraction analysis confirmed that both approaches yielded δ-MnO2 nanostructures with a monoclinic Birnessite phase. The MG sample displayed a coagulated nanoflake-like morphology, as observed in FESEM images. On the other hand, the MH sample exhibited a distinct nanoflower morphology. The materials' optical properties were investigated using UV–visible spectra analysis, revealing direct bandgap energies of 2.2 eV and 2.58 eV for the MG and MH, respectively. The surface area of the MG sample was found to be higher as compared to the MH nanoflower, showcasing a mesoporous structure. XPS analysis was employed to determine the oxidation states of the elements. The effect of varying pH levels on the degradation of Methyl Orange dye by the two nanocatalysts was investigated. The results demonstrated that acidic pH led to higher decolouration efficiency, particularly notable for the MG nanocatalyst. Consequently, this study illustrates that the green δ-MnO2 nanocatalyst effectively degrades methyl orange dye under acidic conditions through photocatalysis.

Fires occurring within buildings present a grave concern, as they entail substantial risks to human lives, property, and the environment. Implementing appropriate fire safety measures becomes imperative to mitigate the occurrence of fires and ensure efficient response in the event of an incident. The primary aim of the study is to examine the performance of various coatings on the residual strengths of the reinforced normal strength self-compacting geopolymer concrete (NSGC) and high strength self-compacting geopolymer concrete (HSGC) columns subjected to standard temperature exposure in accordance with ISO 834 guidelines. The design compressive strength of the concretes was 36.12, 57.06 and 52.8 MPa. Two types of coating were employed in the present investigation namely ceramic wool wrapping and high alumina cement. A computerized electric furnace is used to heat the column specimens. Amongst the forty-two columns developed, six specimens tested without temperature exposure and protective coating as a reference specimen. Twelve specimens were heated as per ISO fire curve and tested to assess the residual axial strength performance and twenty-four specimens were coated with protective layers, then heated and tested to assess the post fire performance. It is exemplified that the composite protective coating offers effective resistance to concrete, gaining optimum axial strength performance. The findings show that these fire protecting composites have a high potential for utilizing as new strengthening techniques for reinforced concrete (RC) columns.

The study assesses the mechanical efficiency, long-lasting characteristics, microstructure, and sustainability of sustainable concrete (SC) samples through several optimization methods, emphasizing the significance of the 3Rs (recycle, reuse, reduce) approach in the construction sector. The study uses advanced techniques like the Taguchi method, grey relational analysis (GRA), analysis of variance (ANOVA), and signal-noise ratio (SNR) to optimize parameters affecting the performance of SC. In this study, the properties of SC are assessed by considering various parameters. These parameters include the use of 10 %, 20 %, and 30 % of ground granulated blast furnace slag (GGBFS) as a replacement for fly ash (FA). Additionally, six different binder contents ranging from 300 kg/m3 to 600 kg/m3 are examined. The study also investigates three different molarities of sodium hydroxide (NaOH) (8 M, 12 M, and 16 M), three different ratios of alkaline activators (AA) (1.5, 2.0, and 2.5), three different AA to-binder ratios (0.30, 0.35, and 0.40), and curing temperature (CT) of 30 °C, 60 °C, and 90 °C. The study includes fresh properties such as fresh density (FD) and slump, mechanical properties such as tensile strength (TS), flexural strength (FS), modulus of elasticity (MOE), and compressive strength (CS), and durability studies such as dry density (DD), impact strength, water absorption (WA), and sorptivity. The blended proportions were obtained using the Taguchi method. The study shows that GGBFS accelerates geopolymerization in FA-based concrete, reducing setting time and early-age CS. FA is crucial for setting time, workability, and CS enhancement. GGBFS increases the densities of fresh and hardened concrete, with a highly correlated increase, allowing accurate hardened density prediction with a coefficient of 0.9057. The CS of the cube SC surpassed 40 MPa, irrespective of variables such as the AA ratio, CT, and NaOH molarity. The trail mix with a binder concentration of 600 kg/m3, 30 % GGBFS content, 12 M NaOH molarity, 1.5 AA ratio, 0.35 AA to binder ratio, and 90 °C CT exhibited the greatest strength. Mixtures containing 10 % GGBFS can attain a CS above 30 MPa after 28 days, making them suitable for structural purposes. The T18 mix exhibited a compact Calcium (alumino) silicate hydrate (C-A-S-H) and N-A-S-H gel, whereas the T3 mix displayed a varied and permeable structure. The study used GRA, ANOVA, and SNR methods to analyze properties varying by six variables, finding GGBFS content as the most influencing parameter. The study found that the SC had a lower sustainability score than the OPC mix, but had better energy efficiency.