Heterocyclic, macrocycle organic compounds, structurally characterized with porphyrins, are not only abundant in nature but also environmentally friendly. These porphyrinic compounds have recently been extensively studied for their fascinating structures, physical properties, and high potentials in engineering applications. We report experimental results on the photonicallyactivated thermal energy conversion via irradiations of white light (simulated solar light). The photothermal effects have been well studied for metallic conductors with large number of charge carriers based on the so-called localized surface plasmon resonance (LSPR). However, the LSPR model may not apply to the porphyrinic materials with very limited number of charge carriers. In this study, we have found several porphyrinic compounds to exhibit pronounced photothermal effects including chlorophyll, chlorophyllin, hemoglobin, and phthalocyanine that all share similar structural characteristics. Raman data show characteristic molecular vibrations from these compounds that are responsible for photon-to-thermal energy conversions near the optical absorption frequencies. We attribute the porphyrin molecular vibrations to the photothermal effects observed from these compounds and predict that all porphyrinic materials can be optically activated for pronounced photothermal effects. Also established is a newly defined Specific Photothermal Coefficient (SPC), a unique photothermal property of the thin films investigated in this study.

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A Cold Atmospheric Plasma (CAP) apparatus was designed and developed for SARS-CoV-2 killing as evaluated by pseudotyped viral infectivity assays. The reactive species generated by the plasma system was fully characterized by using Optical Emission Spectroscopy (OES) measurement under given conditions such as plasma power, flow rate, and treatment time. A variety of reactive oxygen species (ROS) and reactive nitrogen species (RNS) were identified from plasma plume with energies of 15–72 eV in the frequency range between 500–1000 nm. Systematic virus killing experiments were carried out, and the efficacy of CAP treatment in reducing SARS-CoV-2 viral infectivity was significant following treatment for 8 s, with further enhancement of killing upon longer exposures of 15–120 s. We correlated killing efficacy with the reactive species in terms of type, intensity, energy, and frequency. These experimental results demonstrate effective cold plasma virus killing via ROS and RNS under ambient conditions.

In all previous studies of soft magnetic alloys, magnetic softness is obtained through forming a completely amorphous state via rapid solidification, such as by melt spinning at a high cooling rate followed by annealing, typically at 600 °C, to develop a magnetically isotropic nanostructure. Fine powdering of the annealed alloy via ball milling is then required for manufacturing, net shaping, and 3D printing. However, the soft magnetic properties are susceptible to the subsequent processing conditions, characterized by significantly increased coercivity. Herein, nanoscale crystallites are obtained directly from the melt‐spun Fe77Ni5.5Co5.5Zr7B4Cu ribbon (i.e., not through annealing of a completely amorphous ribbon) that exhibits structural stability during the annealing and ball‐milling processes. The melt‐spun ribbon annealed at high temperatures (700 °C) remains magnetically soft with Hc of ≈0 Oe, which is a key property for high‐temperature applications. Ball milling of the annealed melt‐spun samples results in fine powders with low Hc values over a wide temperature range up to 427 °C. It is shown that the rapidly solidified crystalline ribbon provides an ideal precursor for the manufacture of high‐temperature soft magnetic materials. This new approach provides a straightforward method of making soft magnetic alloy powders.

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