Seminar by Assoc. Prof. Arkhincheev Valerii and Dr. Subramanian Ramanathan

TDTU, 10/12/2025

At 2:00 p.m. on December 12, 2025, IAST organized an seminar at Meeting Room B (Tan Hung Campus) and Room 604, 99 Tran Quoc Toan (Hanoi Campus) with detailed content as follows:

1. Assoc. Prof. Arkhincheev Valerii reported on the topic: Topological transitions in LC system. Classic analog of quantum transitions.
Abstract:

This report investigates percolation transitions in a disordered L-C system composed of inductors and capacitors (non-dissipative reactive elements). These transitions occur between different percolating states, resulting in distinct, constant values ​​of the effective conductivity. We employ an exact approach based on the rotational symmetry of two-dimensional DC equations. A new type of topological phase transition is identified for these non-dissipative systems. The characteristics of these transitions, which are analogs of topological invariants, are calculated. We propose that these transitions may be considered a classical analog of quantum transitions, such as the quantum Hall effect.

2. Dr. Subramanian Ramanathan reports on the topic: Rhodamine B dye degradation using waste face mask-derived carbon (UFMC) coupled with peroxymonosulfate (PMS)
Abstract:

Catalytic carbon materials from used face masks (UFM) activated by peroxymonosulfate (PMS) were developed for the degradation of rhodamine B (RhB) dye in aqueous solution. The UFM-derived carbon (UFMC) catalyst had a relatively large surface area as well as active functional groups and promoted the generation of singlet 1O2 and radicals from PMS, giving a high RhB degradation performance (98.1% after 3 h) in the presence of 3 mM PMS. The UFMC could degrade only 13.7% at a minimal RhB dose of 105 M. The principal reactive oxygen species of sulphate (SO 4 • ), hydroxyl radicals ( • OH), and singlet 1O2 were discovered using electron paramagnetic resonance and radical scavenger studies. Finally, a toxicological plant and bacterial study was performed to demonstrate the potential non-toxicity of the degraded RhB water sample.