دکتر محمد سلطانی رنانی

Nanomaterials have significantly transformed multiple scientific and technological fields due to their exceptional properties resulting from their quantum confinement effects and high surface-to-volume ratios. Among these materials, zinc oxide (ZnO) and titanium dioxide (TiO 2) nanoparticles have attracted considerable interest because of their diverse applications. In this study, TiO2-ZnO nanocomposites were synthesized using varying calcination times of 1, 1.5, 2, 2.5, and 3 hours. Characterization of fabricated samples through X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDXS) confirmed the successful fabrication of the nanocomposites. In this regard, XRD analysis revealed anatase TiO2 and hexagonal wurtzite ZnO phases. Raman spectroscopy also supported these findings, identifying characteristic peaks of both TiO2 and ZnO. The calcination time had a minimal effect on the crystal structures and the nanocomposites' morphology, which gave rise to its negligible impact on the samples' optical properties and biological activities. Optical properties assessed using UV-visible and photoluminescence (PL) spectroscopy showed consistent band gap absorption and emission profiles across all samples, among which the nanocomposite calcined for 1 hour exhibited the best optical properties. The sample prepared at 1 hour showed the most favorable optical properties and significant antibacterial, antifungal, and cytotoxic activities, making it suitable for various applications. In this regard, more than 99.9% reduction occurred in the number of Escherichia coli, Staphylococcus aureus bacteria, and Candida albicans fungus using TiO2-ZnO nanocomposite. Besides, adding 500 µg/ml of nanocomposite decreased the cell viability to 34.47%, which signifies its high cytotoxicity activity. © 2025, Iran University of Science and Technology. All rights reserved.

Solid-state analog of gravitational redshift: Transport signatures of massless Dirac fermions in tilted Dirac cone heterostructures

( Article . )

Karmand, M., Amini, M., Soltani renani, M., Ghanbari, E., Jafari, S.A.

Publication Date: 2025

Physical Review Research (26431564)7(3)

A Dirac electron passing through a heterojunction with spatially variable tilt experiences an effective curved spacetime. In this work, we show how this experience is manifested in its conductance. We investigate the propagation of electron waves in a two-dimensional tilted Dirac cone heterostructure where tilt depends on the coordinate z along the junction. The resulting Dirac equation in an emergent curved spacetime for the spinor ψ(z) can be efficiently solved using a fourth-order Runge-Kutta numerical method by a transformation to a suitable spinor φ where the resulting Dirac cone looks locally upright. The spatial texture of the tilt induces oscillatory behaviors in key physical quantities such as the norm |φ(z)|2 of the wave function, polar and azimuthal angles Θ(z) and Φ(z) of the pseudospin, and the integrated transmission τ where oscillation wavelengths get shorter (longer) in stronger (weaker) tilt regions. Such an oscillatory behavior that is reminiscent of gigantic gravitational redshift is an indicator of an underlying spacetime metric that can be probed in tunneling experiments. We derive analytical approximations for the position-depdendent wave numbers Δkz(z) that explain the redshift patterns and corroborate it with numerical simulations. For a tilt bump spread over length scale ℓ, upon increasing ℓ, the amplitude of redshifted oscillations reduces whereas the number of peaks increases. The scale invariance of the Dirac equation allows us to probe these aspects of ℓ dependence by a voltage sweep in transmission experiments. Smooth variations of the tilt reduces impedance mismatch of the electron waves, thereby giving rise to very high transmission rates. This concept can be used in combination with a sigmoid-shaped tilt texture for a gigantic redshift or blueshift engineering of the transmitted waves, depending on whether the sigmoid is downswing or upswing. © 2025 authors. Published by the American Physical Society.

Structural strategies for edge-bulk decoupling in trench-engineered nanoribbons: a conceptual study of electrical power for thermoelectric applications

( Article . )

Kzar, F., Karbaschi, H., Ghanbari, E., Soltani renani, M.

Publication Date: 2025

Physica Scripta (00318949)100(10)

Synthesis of TiO2-ZnO Nanocomposites and Evaluation of their Antibacterial and Antifungal Activities: Effect of Calcination Time

( Article . )

Kadum shakir, A., Ghanbari, E., Baron, A.S., Soltani renani, M.

Publication Date: 2025

Chemical Methodologies (26457776)9(3)pp. 233-250

Nanomaterials have significantly transformed multiple scientific and technological fields due to their exceptional properties, which result from their quantum confinement effects and high surface-to-volume ratios. Among these materials, zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles have attracted considerable interest because of their diverse applications. In this study, TiO2-ZnO nanocomposites were synthesized using varying calcination times of 1, 1.5, 2, 2.5, and 3 hours. Characterization of fabricated samples through X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDXS) confirmed the successful fabrication of the nanocomposites. In this regard, XRD analysis revealed anatase TiO2 and hexagonal wurtzite ZnO phases. Raman spectroscopy also supported these findings, identifying characteristic peaks of both TiO2 and ZnO. The calcination time had a minimal effect on the crystal structures and also morphology of the nanocomposites, which gave rise to its negligible impact on optical properties and biological activities of the samples. Optical properties assessed by means of UV-visible and photoluminescence (PL) spectroscopy showed consistent band gap absorption and emission profiles across all samples, among which the nanocomposite calcined for 1 hour exhibited the best optical properties. The sample prepared at 1 hour not only showed the most favorable optical properties, but also demonstrated significant antibacterial, antifungal, and cytotoxic activities, which make it suitable for various applications. In this regard, a reduction of more than 99.9% occurred in the number of Escherichia coli and Staphylococcus aureus bacteria and also Candida albicans fungus by using TiO2-ZnO nanocomposite. Besides, addition of 500 µg/mL of nanocomposite decreased the cell viability to 34.47%, which signifies its high cytotoxicity activity. © 2025, Sami Publishing Company. All rights reserved.

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