Articles
Publication Date: 2025
Optics Continuum (27700208)4(8)pp. 1676-1686
The Hα emission line at 656.3 nm is a crucial spectral wavelength for studying astrophysical and solar phenomena, such as ionized hydrogen regions and chromospheres’ activity. To facilitate precise and detailed observations at this wavelength, we designed four high-performance Hα filters. These filters exhibit a full width at half maximum of approximately 1 nm or less and achieve peak transmittance exceeding 95%. Utilizing multiple beam interference based on the Fabry-Perot principle, with niobium pentoxide (Nb2 O5) and magnesium fluoride (MgF2) layers, the design ensures exceptional spectral isolation within the 625–740 nm range. This outstanding performance makes the filters highly suitable for advanced astrophysical research and solar imaging. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
Publication Date: 2025
International Journal of Systems Science (00207721)56(8)pp. 1726-1741
Piezoelectric deformable mirrors are complex systems with a reflective face-sheet and underlying actuators. The inherent hysteresis phenomenon in piezoelectric materials introduces nonlinearity and delay, rendering conventional control methods inappropriate for deformable mirror actuation. This study presents a disturbance observer-based controller with the generalised Bouc–Wen hysteresis parameter identification algorithm. Analytical proofs establish fixed-time stability for the observer and controller. A key feature of the proposed disturbance observer is the convergence of the estimated hysteresis to the actual value after a prescribed settling time, which facilitates precise hysteresis parameter identification. This is based on a data clustering technique, unlike most previous works. The proposed controller has the capability of hysteresis compensation and reference tracking in the piezoelectric deformable mirror actuators. Numerical simulation results are present to evaluate the tracking performance of the controller in the presence of random wavefront, the convergence of disturbance to the actual value in the fixed time, and identification of hysteresis parameters. © 2024 Informa UK Limited, trading as Taylor & Francis Group.
Publication Date: 2025
Chemical Methodologies (26457776)9(11)pp. 1031-1040
The development of antibacterial textiles is essential for applications in healthcare, hygiene, and protective clothing. Among various approaches, Copper oxide nanoparticles (CuO NPs) were successfully deposited onto cotton fibres using an ultrasonic spray-coating technique to enhance their antibacterial functionality. The molarity of the precursor solution was identified as a critical factor influencing the morphology, structural properties, and antibacterial efficacy of the coated cotton fibres. Two molar concentrations (0.03 M and 0.06 M) were used to assess the effect of CuO loading on the coating characteristics and antibacterial performance. The treated fabrics were rigorously evaluated against two bacterial strains: Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). Comprehensive morphological and structural characterization of the CuO films was conducted using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) to determine surface uniformity, particle distribution, and crystallinity of the deposited thin films. The biological findings revealed that the CuO-coated fabrics exhibited significant antibacterial activity against both bacterial strains with increased effectiveness observed at the higher molarity. These findings indicate that ultrasonic deposition of CuO thin films on cotton fibres provides a promising route for producing antimicrobial textiles with potential applications in medical, hygienic, and protective clothing. Overall, CuO-coated cotton fabrics demonstrated effective bacterial inhibition, highlighting their potential for antimicrobial textile applications. The molarity of the CuO solution significantly influences both coating quality and antibacterial efficacy. © 2025 by Sami Publishing Company This is an open access article under the CC BY license.
