Herein, we report the phytogenic, single-step synthesis of silver/reduced graphene oxide (Ag/rGO) nanocomposites utilizing Citrus macroptera peel extract as a sustainable, dual reducing and stabilizing agent. Spectroscopic and diffractometric analyses (UV–vis, FTIR, Raman, EDX, and XRD) confirmed the synchronized bio-reduction of graphene oxide (GO) and silver ions (Ag + ), yielding highly crystalline metallic ‘Ag’ anchored on an exfoliated reduced graphene oxide (rGO) matrix. Electron microscopy (SEM and TEM) analyses established the homogeneous immobilization of ultrafine, spherical silver nanoparticles (AgNPs) in the tens-of-nanometers scale across wrinkled, semi-transparent, and exfoliated rGO nanosheets. Benefiting from a synergistic interfacial electron-transfer mechanism, the Ag/rGO nanocomposite demonstrated vastly superior catalytic efficiency for 4-nitrophenol reduction (9 min, 97.5 s −1 g −1 ) compared to pristine AgNPs (18 min, 87.2 s −1 g −1 ) and their corresponding physical mixtures (AgNPs & rGO synthesized using same extract). Furthermore, the hybrid material exhibited potent, broad-spectrum antibacterial activity against critical pathogens, including Escherichia coli , Staphylococcus aureus , Vibrio cholerae , and Salmonella typhi . This study establishes a green, waste-to-wealth fabrication strategy for multifunctional nano-architectures, offering potential solutions for environmental remediation and biomedical applications.
Existing multidimensional housing affordability assessments have yet to adequately explain how neighborhood physical-spatial conditions, residents' priorities, and residential satisfaction are interrelated. This study investigates the sustainability of housing affordability by developing an integrated conceptual framework that recognizes financial affordability and neighborhood livability as two interrelated dimensions of sustainable housing affordability. Grounded in housing affordability, neighborhood design, and residential satisfaction scholarship, the framework integrates six criteria and twenty-four indicators. Employing a mixed-methods comparative approach, the research examines two planned neighborhoods in Khulna, Bangladesh, through morphological mapping and built-environment analysis, 200 semi-structured household interviews, Residents' Preference and Satisfaction Indices (RPI and RSI), and separate multiple linear regression models. The physical-spatial analysis reveals contrasting neighborhood qualities: mixed land use and interconnected streets support accessibility and social interaction but are constrained by congestion, inadequate pedestrian infrastructure, and limited public spaces; conversely, more controlled residential layouts provide spatial order and greenery but restrict access to everyday services and informal social spaces. Residents assigned high importance to housing price/rent in both neighborhoods, alongside differing priorities concerning walkability, infrastructure connectivity, and environmental quality. Overall residential satisfaction with neighborhood livability varied between the neighborhoods, with contrasting patterns across income groups. The regression models exhibited substantial within-sample explanatory fit, identifying significant associations between neighborhood satisfaction and the perceived importance of commuting-related attributes, natural elements, social space, sense of place, and crime rates. By integrating physical-spatial evidence with residents’ priorities and satisfaction, the study advances multidimensional housing affordability assessment and provides an empirical basis for context-sensitive neighborhood design and planning guidelines that promote neighborhood livability and sustainable residential development.
Herein, we report the phytogenic, single-step synthesis of silver/reduced graphene oxide (Ag/rGO) nanocomposites utilizing Citrus macroptera peel extract as a sustainable, dual reducing and stabilizing agent. Spectroscopic and diffractometric analyses (UV–vis, FTIR, Raman, EDX, and XRD) confirmed the synchronized bio-reduction of graphene oxide (GO) and silver ions (Ag+), yielding highly crystalline metallic ‘Ag’ anchored on an exfoliated reduced graphene oxide (rGO) matrix. Electron microscopy (SEM and TEM) analyses established the homogeneous immobilization of ultrafine, spherical silver nanoparticles (AgNPs) in the tens-of-nanometers scale across wrinkled, semi-transparent, and exfoliated rGO nanosheets. Benefiting from a synergistic interfacial electron-transfer mechanism, the Ag/rGO nanocomposite demonstrated vastly superior catalytic efficiency for 4-nitrophenol reduction (9 min, 97.5 s−1g−1) compared to pristine AgNPs (18 min, 87.2 s−1g−1) and their corresponding physical mixtures (AgNPs & rGO synthesized using same extract). Furthermore, the hybrid material exhibited potent, broad-spectrum antibacterial activity against critical pathogens, including Escherichia coli, Staphylococcus aureus, Vibrio cholerae, and Salmonella typhi. This study establishes a green, waste-to-wealth fabrication strategy for multifunctional nano-architectures, offering potential solutions for environmental remediation and biomedical applications.
The green pathway is considered an alternative to the conventional chemical method for synthesising metal nanoparticles. This study demonstrates a facile biogenic synthesis of bismuth nanoparticles (BiNPs) using Piper chaba stem extract as a reducing and capping source. Synthesised BiNPs were characterised using various analytical tools. XRD analysis confirmed the formation of crystalline BiNPs. FTIR analysis identified the functional groups from P. chaba extract involved in the BiNPs stabilisation process, while zeta potential measurement confirmed their stabilisation. The TEM image revealed spherical nanoparticles with an average size of 15 nm. EDX analysis showed bismuth as the dominant element, with traces of carbon and oxygen from organic moieties on the surface of BiNPs. TGA also supports the existence of phytochemicals with BiNPs and good thermal stability up to 800 degrees C, supporting its suitability for high-temperature applications. The catalytic activity of BiNPs in reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4 showed rapid conversion of 4-NP to 4-AP within 22 min, with a rate constant of 6.77 s(-1) g(-1), demonstrating the excellent catalytic efficiency of BiNPs. Following green chemistry principles, these findings suggest that P. chaba-mediated BiNPs can serve as highly effective nanocatalysts for various chemical transformations and environmental purification processes.
Yttrium-substituted Co0.5Cu0.5YxFe2-xO4 ferrites (x = 0.00, 0.03, 0.06, 0.09) were synthesized via conventional solid-state route and sintered at 800 °C to explore their structural, optical, and magneto-dielectric characteristics. X-ray diffraction confirmed a predominant cubic spinel phase, with orthoferrite secondary phases appearing at higher Y contents. The lattice parameter initially expanded to 8.376 Å (x = 0.03) but decreased systematically to 8.356 Å, lower than the undoped value (8.362 Å) at x = 0.09. SEM revealed well-crystallized grains with reduced grain size from 180.25 μm to 108.76 μm, corroborated by EDS showing stoichiometric composition. Optical studies indicated a widening band gap from 3,80 eV to 5.05 eV with Y incorporation. Dielectric measurements showed a significant drop in dielectric constant (1305.01 → 183.41) and loss tangent (2.22 → 1.24) with doping and frequency, consistent with interfacial polarization. Electric modulus analysis revealed an increased Mɛ′ value (0.044 at x = 0.09) and relaxation peaks in Mɛ″ shifting from 3.28 kHz to 11 kHz, indicating grain boundary relaxation. Nyquist impedance spectra exhibited dual arcs associated with grain (Mɛ″ ≈ 0.008 at x = 0.09) and grain boundary (Mɛ″ ≈ 0.0045 at x = 0.09) contributions. Magnetic characterization showed imaginary permeability ranging from 2479.8 to 3022 and energy loss factors between 298 and 340 at low frequencies, both declining rapidly beyond 3 kHz. Compressed magnetic Nyquist arcs with increasing Y confirmed enhanced AC conductivity, with x = 0.09 delivering the smallest arc and superior performance. Notably, this composition achieved impedance matching of 0.68 at 0.6 MHz, indicating promising electromagnetic behavior in the MHz range, with potential applicability in high-frequency devices pending further investigation in the GHz regime.
