Comparison of the physicochemical properties and inactivation against tumor cells of PAW induced by underwater single-hole and multi-hole bubble plasmaLiu, Zhijie; Gao, Yuting; Pang, Bolun; Wang, Sitao; Tantai, Xiamin; Zhang, Feng; Li, Qiaosong; Xu, Dehui; Liu, Dingxin
doi: 10.1088/1361-6463/ac6a8apmid: N/A
Plasma-activated water (PAW) regarded as a green alternative is of great interest in biomedicine due to the presence of a rich diversity of aqueous reactive oxygen and nitrogen species (RONS). Optimizing the reactor parameter is an important approach to regulate RONS in PAW to obtain better biological effects. This work mainly focuses on the number of micro holes of the plasma device to realize underwater bubble discharge. By comparing single-hole and multi-hole plasma under the same pulse voltage, the multi-hole plasma would produce a better discharge characteristic, and the prepared PAW presents superior physicochemical properties to realize high level RONS production by means of microbubbles to increase the contact area with water molecules. Furthermore, the A549 lung carcinoma cells are used to verify the inactivation effect induced by PAW treated by underwater single-hole and multi-hole bubble plasma, respectively, and the results show that the multi-hole plasma would induce cell apoptosis reaching up to 57.4%, while only 31.2% apoptosis efficiency for single-hole plasma. This mainly contributes to the high concentration of key species (NO2−, H2O2, ONOO−/O2−, and ·OH) produced by multi-hole plasma. This study is helpful to insight into the influence of underwater bubble on chemistry activity of PAW, and promoting the wide applications in biomedical field.
Terahertz gas discharge: current progress and possible applicationsSidorov, A V
doi: 10.1088/1361-6463/ac5556pmid: N/A
Plasma created in focused beams of electromagnetic waves in the terahertz frequency range is a fairly new object in gas discharge physics. The specified range, located between the microwave and infrared regions of the spectrum of electromagnetic waves, is currently being actively developed. However, until recently, the study of discharge phenomena in it was practically inaccessible. Recent advances in its development are associated primarily with the creation of powerful sources of terahertz radiation—gyrotrons and free electron lasers. This article presents an overview of the latest results of studies of a gaseous terahertz discharge: gas breakdown, discharge propagation, features of the discharge glow, and prospects for a gaseous terahertz discharge as a point source of UV radiation.
Enhanced Smith–Purcell radiation from bound states in the continuum of metallic gratingsChen, Zhaofu; Mao, Leilei; Jin, Mengmeng; Shi, Xin; Bai, Ningfeng; Sun, Xiaohan
doi: 10.1088/1361-6463/ac6a8bpmid: N/A
The enhancement of Smith–Purcell radiation (SPR) produced by electrons moving closely to a grating is a longstanding topic of interest. Here, we systematically investigate the resonant enhancement of SPR for planar metallic gratings. Using an analytic solution for the amplitude of SPR, we show that metallic gratings with a small dutycycle support two type of bound states in the continuum (BICs), i.e. symmetry-protected BICs and accidental BICs, both of which enable the SPR to be enhanced by orders of magnitude at the resonant frequency. The required electron energy for the excitation of BICs can be reduced by employing a higher-order diffraction wave for SPR. Our results present a mechanism for enhancing the SPR produced by metallic gratings, and may find applications in free-electron lasers.
Review on magnonics with engineered spin texturesPetti, Daniela; Tacchi, Silvia; Albisetti, Edoardo
doi: 10.1088/1361-6463/ac6465pmid: N/A
Spin textures, such as non-uniform domain arrangements, domain walls and skyrmions are naturally occurring structures in magnetic materials. Recently, the unique properties of spin textures such as their reconfigurability, stability and scalability towards nanoscale dimensions, has sparkled the interests towards their use as active elements in spintronic devices. In the framework of magnonics, which aims to use spin waves (SWs) for carrying and processing information, using spin textures allows to harness an extremely rich phenomenology for designing new functionalities. In this review, we focus on the recent developments on the control and stabilization of engineered spin textures, and their applications in the field of magnonics. First, we introduce the main techniques used for stabilizing the spin textures and controlling their properties. Then we review the recent results on the use of engineered spin textures for guiding, emitting and manipulating SWs, and the recent proposals on the realization of complex functionalities using integrated spin-texture-based systems, which hint to possible future directions for technological prospects.
Transport and radiation properties of C4F7N-CO2 gas mixtures with added oxygenNarayanan, Venkat R T; Gnybida, Mykhailo; Rümpler, Christian
doi: 10.1088/1361-6463/ac6af5pmid: N/A
Owing to global and local legislative mandates pertaining to greenhouse gas emission reduction targets, the focus of industries dealing with electrical power management has shifted towards SF6 replacement within electrical or electro-mechanical equipment since 2010. In particular, fluoronitrile- (C4F7N) or fluoroketone- (C5F10O) based gas mixtures have been identified as the most promising candidates for this purpose in both medium-voltage (MV) and high-voltage (HV) gas insulated switchgear (GIS). The temperature and pressure ranges of interest are 300 K–30 kK and 1–5 bars respectively, which are relevant to the short-circuit current arcing conditions within an MV-GIS. In this work, we focus on a gas mixture with a fluoronitrile mole fraction lower than 20%, with or without O2 having a mole fraction lower than 20% and the rest of the mixture was carbon dioxide (CO2). Throughout this work, we validate our calculation results with published data for 10% and 20% C4F7N-CO2 mixtures at 1 bar and 5 bars and hint at the possible sources of discrepancies. Our local thermodynamic equilibrium based chemical composition results indicate that the addition of 20% O2 to C4F7N-CO2 mixtures significantly reduced CO formation while increasing COF2 formation. However, the addition of 20% O2 induced marginal modifications to the thermodynamic, transport and radiation properties of 10% and 20% C4F7N-CO2 mixtures. Finally, after utilizing the properties database to calculate steady-state temperature profiles for a low-current (10 A) free-burning arc without metallic vapor, we demonstrate that the arc columns of 10% and 20% C4F7N-CO2 mixtures with or without O2 are less diffuse compared to air but more diffuse compared to SF6. We explain the order of diffuse-to-constricted profiles and arc interruption capabilities for different gases in terms of their thermal conductivities and diffusivities.
Random lasers from the natural inverse photonic glass structure of Artemia eggshellsMai, Hanh Hong; Nguyen, Trong Tam; Nguyen, Tien Thinh; To, Thanh Thuy; Nguyen, Toan T; Choi, Youngwoon; Choi, Wonshik; Ta, Van Duong
doi: 10.1088/1361-6463/ac6a25pmid: N/A
In this study, we demonstrate a simple approach to fabricate a high-performance random laser (RL) from the natural inverse photonic glass structure of Artemia eggshells. Herein, the three-dimensional structures of Artemia eggshells provide an ideal scattering medium with a significantly high-reflectance stopband which facilitates resonance feedback for random lasing action. By doping organic dye molecules into the Artemia eggshells, RLs are realized by optical pumping with a threshold of 79 μJ mm−2, and a quality (Q) factor of 2328. In comparison with other works on RLs from natural photonic crystals such as butterfly wings, our RLs demonstrate a significantly lower lasing threshold and a comparable Q factor. Our results indicate that the natural inverse photonic glass structure is not only served as an effective scattering medium for random lasing but also paves a novel approach in designing and fabricating bio-controlled photonic devices.
Modulation of the spin transport properties of γ-graphyne by chemical anchoring groups and strainLi, Yun; Li, Xiaobo; Zhang, Xiaojiao; Zhang, Shidong; Long, Mengqiu
doi: 10.1088/1361-6463/ac5b44pmid: N/A
Chemical anchoring groups can modulate the connection between metal electrode surfaces and central molecules and regulate the distribution of electronic states and charge transport in monomolecular device energy levels. Thus, the introduction of different anchoring groups inevitably has an influence on multifunctional molecular devices. Moreover, the strain effect is also an important method for electronic property modulation of two-dimensional materials. Therefore, in this paper, three different chemical anchoring groups are combined with compressive and tensile strains, aiming for dual-modulation behavior in the spin-resolved transport properties of γ-graphyne molecular devices. Our calculation results suggest that the chemical anchoring groups of pyrrole (C4H5N), thiophene (C4H4S), and 1H-phosphole (C4H5P) molecules combined with strain have a good regulatory effect on the transport of designed molecular devices, which can be seen from the transmission spectra and molecular energy spectrum. In addition, the dual modulation can induce the spin-polarization phenomenon and the maximum spin filtering efficiency reaches 90%. Furthermore, negative differential resistance behavior has been achieved in the proposed device, and the maximum peak-to-valley ratio can reach 12.14. Our findings may provide a theoretical basis for the dual modulation of molecular junctions by chemical anchoring groups and strain for future nanoelectronic devices.
Human coronavirus inactivation by atmospheric pressure helium plasmaSasaki, Shota; Osana, Shion; Kubota, Takahiro; Yamaya, Mutsuo; Nishimura, Hidekazu; Nagatomi, Ryoichi; Kaneko, Toshiro
doi: 10.1088/1361-6463/ac6a8cpmid: N/A
The recent global pandemic of Corona Virus Disease-19 has impacted all aspects of society, producing a growing demand for a powerful virus inactivation method. To assess a potential and mechanism of human coronavirus inactivation using atmospheric pressure plasma (APP) technology, replication of a human coronavirus (HCoV-229E) after He + H2O APP plume exposure was evaluated using rhesus monkey kidney epithelial cells. The HCoV-229E titers were reduced by 3 log10TCID50 after the APP exposure for 30 s, showing a strong virus-inactivation efficacy of the APP. It was experimentally verified that the APP produced the liquid-phase reactive oxygen and nitrogen species (RONS) at high rates [e.g. •OH: ∼1.7 nmol s−1, H2O2 (including H2O2 precursors): ∼9.2 nmol s−1, NO2− (including NO2− precursors): ∼3.3 nmol s−1]. However, an administration of H2O2 with NO2− failed to inactivate the virus and only Mn type superoxide dismutase among several RONS scavengers for •OH, HO2•/O2•−, 1O2, and •NO/•NO2 was significantly effective for the recovery of the APP-induced decrease in the viral titers. This suggests O2•−-related chemical reaction in a network of interconnected reactions induced by the APP exposure is very important for the APP-induced virus inactivation. These results provide new insight into a more efficient inactivation method of human coronavirus using APPs.