Pseudo-photocatalysis driven by argon-plasma-system (AP) is a new approach toward the promotion of reactive species production for water remediation. Here, we investigated the synergistic effect between AP and catalyst by altering the oxygen vacancies (OV) concentration of CeO2/Bi2O3 for stimulating the hydrated electrons (eaq- ) production for PFOA removal. The soft X-ray total fluorescence yield (TFY) analysis and DFT calculation revealed the formation of the built-in electric field in the Bi/Ce0.43 interface can enhance interfacial electron migration with direction from Bi2O3 toward CeO2, simultaneously promoting the eaq- generation. Notably, AP-Bi/Ce0.43 (0.1488 min-1, EEO = 0.43 kW mg-1) exhibited excellent PFOA removal kinetic performance with almost 5.7 times faster and 72.6% lower energy consumption than sole AP (0.0261 min-1, EEO = 1.57 kW mg- 1), respectively. The multiple-plasma-jet continuous-flow-experiments results illustrated the scalability of AP-Bi/Ce0.43 for PFOA destruction. Our findings demonstrate fundamental insights into the synergistic effect of PFOA removal in AP catalysis.

The purpose of this paper is to provide an in-depth review of plasmonic metal nanoparticles made from rhodium, platinum, gold, or silver. We describe fundamental concepts, synthesis methods, and optical sensing applications of these nanoparticles. Plasmonic metal nanoparticles have received a lot of interest due to various applications, such as optical sensors, single-molecule detection, single-cell detection, pathogen detection, environmental contaminant monitoring, cancer diagnostics, biomedicine, and food and health safety monitoring. They provide a promising platform for highly sensitive detection of various analytes. Due to strongly localized optical fields in the hot-spot region near metal nanoparticles, they have the potential for plasmon-enhanced optical sensing applications, including metal-enhanced fluorescence (MEF), surface-enhanced Raman scattering (SERS), and biomedical imaging. We explain the plasmonic enhancement through electromagnetic theory and confirm it with finite-difference time-domain numerical simulations. Moreover, we examine how the localized surface plasmon resonance effects of gold and silver nanoparticles have been utilized for the detection and biosensing of various analytes. Specifically, we discuss the syntheses and applications of rhodium and platinum nanoparticles for the UV plasmonics such as UV-MEF and UV-SERS. Finally, we provide an overview of chemical, physical, and green methods for synthesizing these nanoparticles. We hope that this paper will promote further interest in the optical sensing applications of plasmonic metal nanoparticles in the UV and visible ranges.

This research studied the effects of hydrogen addition on the structural, optical, and catalytic properties of silver nanoparticles (AgNPs) synthesized by an atmospheric-pressure argon plasma jets with a submerged nozzle. A 3% hydrogen-mixed argon (H2–Ar) plasma jet rapidly and efficiently produced more AgNPs than a pure argon (Ar) plasma jet. Moreover, a submerged plasma jet enhanced the synthesis of AgNPs compared to an atmospheric-pressure plasma jet with its nozzle above the solution. Electrical conductivity, acidity, and hydrogen emission measurements suggested that the efficient and rapid synthesis of AgNPs was due to an increase in the aqua-electron and atomic-hydrogen concentrations caused by the interaction between the H2–Ar plasma and the silver precursor solution. The H2–Ar plasma jet-synthesized AgNPs exhibited strong catalytic effects for rhodamine-B dye and Saccharomyces cerevisiae cells. The H2–Ar plasma synthesis of AgNPs is rapid, low cost, and environmentally friendly. We hope that this research will promote the broader use of metal nanoparticles.

Citrate-capped silver nanoparticles (Ag@Cit NPs) were synthesized by a simple plasma-assisted reduction method. Homogenous colloidal Ag@Cit NPs solutions were produced by treating a AgNO3-trisodium citrate-deionized water with an atmospheric-pressure argon plasma jet. The plasma-synthesized Ag@Cit NPs exhibited quasi-spherical shape with an average particle diameter of about 5.9−7.5 nm, and their absorption spectra showed surface plasmon resonance peaks at approximately 406 nm. The amount of Ag@Cit NPs increased in a plasma exposure duration-dependent manner. Plasma synthesis of Ag@Cit NPs was more effective in the 8.5 cm plume jet than in the shorter and longer plume jets. A larger amount of Ag@Cit NPs were produced from the 8.5 cm plume jet with a higher pH and a larger number of aqua electrons, indicating that the synergetic effect between plasma electrons and citrate plays an important role in the plasma synthesis of Ag@Cit NPs. Plasma-assisted citrate reduction facilitates the synthesis of Ag@Cit NPs, and citrate-capped nanoparticles are stabilized in an aqueous solution due to their repulsive force. Next, we demonstrated that plasma-synthesized Ag@Cit NPs exhibited a significant degradation of methylene blue dye.

This research investigated the capture of nitrate by magnesium ions in plasma-activated water (PAW) and its antifungal effect on the cell viability of the newly emerged mushroom pathogen Cryptococcus pseudolongus. Optical emission spectra of the plasma jet exhibited several emission bands attributable to plasma-generated reactive oxygen and nitrogen species. The plasma was injected directly into deionized water (DW) with and without an immersed magnesium block. Plasma treatment of DW produced acidic PAW. However, plasma-activated magnesium water (PA-Mg-W) tended to be neutralized due to the reduction in plasma-generated hydrogen ions by electrons released from the zero-valent magnesium. Optical absorption and Raman spectra confirmed that nitrate ions were the dominant reactive species in the PAW and PA-Mg-W. Nitrate had a concentration-dependent antifungal effect on the tested fungal cells. We observed that the free nitrate content could be controlled to be lower in the PA-Mg-W than in the PAW due to the formation of nitrate salts by the magnesium ions. Although both the PAW and PA-Mg-W had antifungal effects on C. pseudolongus, their effectiveness differed, with cell viability higher in the PA-Mg-W than in the PAW. This study demonstrates that the antifungal effect of PAW could be manipulated using nitrate capture. The wide use of plasma therapy for problematic fungus control is challenging because fungi have rigid cell wall structures in different fungal groups.

Effective low melting-point Dy-diffusion for grain boundary diffusion treatment for enhancing coercivity in Nd-Fe-B-type magnet was found in the DyF3-LiF binary system. Efficacy of the low melting-point (DyF3-LiF) diffusion source as Dy-diffusion source for enhancing coercivity in the diffusion processed Nd-Fe-B-type magnet was investigated. Speedier and more profound coercivity enhancement in the Nd-Fe-B-type magnet was achieved by grain boundary diffusion using the low melting-point (DyF3-LiF) diffusion source with respect to solid DyF3 single salt. Since the liquid in the (DyF3 -LiF) mixture contained plenty of Dy atoms already freed from DyF3 and they were in better contact with magnet, speedier and profuse diffusion of Dy atoms through Nd-rich grain boundary was possible in the magnet coated with low melting-point (DyF3-LiF) diffusion source.

The chiroptical properties of polyfluorene–phenylene (ℎ) thin films were studied using circular dichroism (CD), surface-enhanced Raman scattering (SERS), attenuated total reflection (ATR), and spectroscopic ellipsometry. The pristine ℎ films exhibited significant CD at room temperature, and the chirality increased by thermal annealing at 120 ℃. SERS and ATR spectra indicated that the chirality enhancement was due to the self-organization and/or rearrangement of the polymer backbones by thermal annealing. Optical sensing of the chiral polymers was demonstrated using SERS spectra of the chiral polymer films on gold. Optical sensing properties of the chiral ℎ films were compared with those of the achiral polyfluorene films.

Plasma-activated water (PAW) has emerged as a platform for sterilizing fungal pathogens. In this study, we investigated the influence of PAW on black melanized spores of Aspergillus brasiliensis to explore the mechanism of fungal spore inactivation. PAW was prepared by activating deionized water with a nonthermal atmospheric pressure air plasma jet (soft plasma jet). The concentrations of H2O2 and NOx in the PAW treated by the soft plasma jet for 3 min were 50 μM and 1.8 mM, respectively, and the pH of the PAW was 3.10. The reactive oxygen and nitrogen species (RONS) in the PAW increased with longer plasma activation time. After being treated for 30 min in the PAW with a plasma activation time of 3 min, the spore viability dramatically dropped to 15%. The viabilities of 0.3% H2O2- and 0.3% HNO3-treated spores were 22% and 42%, respectively. The breakage of the spore cell wall by the PAW was revealed in scanning electron microscope images and flow cytometry measurements. Disruption of cell wall integrity provides a path for intracellular components to escape and RONS of the PAW can attack intracellular components directly. Degradation of high molecular genomic DNA was also observed by agarose gel electrophoresis. These results suggest that long-lived reactive species generated in the PAW play an important role in the inactivation of melanized fungal spores. Consequently, PAW produced by a soft plasma jet can be applied to sterilize bioprotective walled fungal spores in a relatively large volume.

Texture development in the Ce-substituted Nd-Fe-B-type die-upset hybrid magnet, which was fabricated using starting materials of Ce-substituted (Nd0.55Ce0.45)(15) Fe72.2Co6.6Ga0.6B5.6 HDDR-treated alloy powder and meltspun Nd-13.6Fe73.6Co Ga-6.6(0).B-6(5.6) flakes (MQU-F) without Ce, was investigated. Noticeably better texture developed in die-upset magnet from the MQU-F flakes alone with respect to magnet from the HDDR-treated powder alone. Better texture developed also in the MQU-F flake regions in the die-upset hybrid magnet with respect to the HDDR particle regions, and overall texture in the hybrid magnet was dominantly controlled by the texture in the MQU-F flake regions. Overall texture in the hybrid magnet was not as good as the weighted average of texture expected from texture of the single alloy magnets from the IIDDR powder alone and the MQU-F flakes alone.

Ce-containing (Nd,Ce)-Fe-B-type hybrid magnet was fabricated by die-upset technique using two different types of materials: Ce-substituted (Nd0.55Ce0.45)(15)Fe72.2Co6.6Ga0.6B5.6 HDDR powder and melt-spun Nd13.6Fe73.6CO6.6Ga0.6B5.6 flakes. Magnetic performance of the hybrid magnet was superior to that of the single alloy magnet when they had identical overall composition: H-i(c)= 6.8 kOe, M-r = 10.6 kG, and (BH)(max) = 19.8 MGOe for the Ce-containing hybrid magnet and H-i(c )= 3.9 kOe, M-r = 9.8 kG, and (BH)(max) = 11.6 MGOe for the magnet from the single alloy HDDR powder. Die-upset hybrid magnet consisting of two constituent materials showed smooth and single-material-like demagnetization behavior, and this was attributed to the exchange interaction between neighbouring grains in the magnet.

Nd-Fe-B-type die-upset magnet with high electrical resistivity was fabricated by hot-deforming the mixture of melt-spun Nd-Fe-B-type flakes (MQU-F: Nd13.6Fe73.6Co6.6Ga0.6B5.6) and Dy-containing salts: eutectic (DyF3-LiF) salt mixture and DyF3 single salt. Profound electrical resistivity enhancement was feasible in the Nd-Fe-B-type die-upset magnet by adding Dy-containing salts. More profound electrical resistivity enhancement was achieved in the magnet added with dielectric eutectic (DyF3-LiF) salt mixture with respect to the magnet added with single DyF3 salt. This was attributed to better electrical insulation between the flakes by forming more continuous coverage of the flake interface with the easily melted dielectric salt. Coercivity of the die-upset magnet was also profoundly enhanced by optimal addition of Dy-containing salts, and this was attributed to substitution of some Nd in the Nd2Fe14B-type grains near flake surface by Dy atoms from the added salt. Kerr microscopy revealed that for both the magnets with or without salt addition, formation of reverse domain initiated mostly inside the flake. Reversed domain started to form at higher reverse field for the magnet added with Dy-containing salt than for the magnet without salt addition. Practical demagnetization occurred largely by formation of new reverse domains at random places rather than enlargement of previously formed reverse domain for both the magnets with or without salt addition.

Atmospheric-pressure A r plasma jets are known to be detrimental to Cordyceps pruinosa spores. However, it is not clear what kinds of reactive species are more effective with regard to fungal cell death. Herein, we study which reactive species plays pivotal roles in the death of fungal spores using an electric shock-free, atmospheric-pressure air plasma jet, simply called soft plasma jet. Plasma treatment significantly reduced the spore viability and damaged fungal DNA. As observed from the circular dichroism spectra, scanning electron microscope images, and flow cytometric measurements, cell wall integrity was decreased by reactive oxygen and nitrogen species (RONS) from the plasma itself and the plasma-activated water. Consequently, degradation of the spore cell wall allows RONS from the plasma to reach the intracellular components. Such plasma-induced intracellular RONS can attack spore DNA and other intracellular components, as confirmed by electrophoresis analysis and phosphorylated histone measurement. In addition, weakening of the spore cell wall allowed for the loss of intracellular components, which can lead to cell death. Plasma radicals were investigated by measuring the optical emission spectrum of the soft plasma jet, and intracellular reactive oxygen species were confirmed by measuring the fluorescence of 2′, 7′-dichlorodihydrofluorescein-diacetate ( H 2 D C F - D A )-stained spores. The soft plasma jet generated considerable amounts of H 2 O 2 and N O x but a very small number of O H radicals as compared to the atmospheric-pressure A r plasma jet; this indicates that plasma-induced long-lived reactive species ( H 2 O 2 and N O x ) play an important role in the weakening of spore cell walls and cell death.

In this research, we investigated the chiroptical properties of chiral-achiral polymer blends consisting of poly[(9,9-bis((S)-3,7-dimethyloctyl)-9H-fluoren-2,7-diyl)- alt-(4-phenylene)] and poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (PFPh-F8BT). The chirality of the blend film decreased on increasing the composition of the achiral polymer. However, the measured circular dichroism values of the blends with high content of F8BT were lower than expected considering the composition of the chiral PFPh polymer, suggesting that the chirality of the blend film was governed by the steric hindrance of the achiral polymeric dopant. Next, we examined optical sensing of the chiral-achiral polymer blends using gold nanoparticles (AuNPs) prepared using the citrate reduction and Ostwald ripening methods. Transmission electron microscopy images showed that the as-made AuNPs had a monodispersed spherical shape with an average diameter of 89 nm. The optical absorption spectrum of the calcined AuNP film exhibited a surface plasmon resonance wavelength at 550 nm. Raman scattering intensities of the PFPh-F8BT blends on the AuNPs were higher than those on fused silica glass; the observed Raman enhancement could be attributed to the optical confinement effects of the AuNPs. Surface-enhanced Raman scattering spectra of the PFPh-F8BT blends revealed that the 1546 cm(-1) Raman peak could be used to estimate the composition of F8BT within the PFPh-F8BT blend.

Anisotropic ceramics-bonded Nd-Fe-B-type magnet with high electrical resistivity was fabricated with the intention of suppressing induction of eddy current thus lowering operating temperature of the magnet used as rotor magnet in high-speed motor. The ceramics-bonded Nd-Fe-B-type magnet was fabricated by consolidating mixture of hydrogenation decomposition desorption recombination powder and oxide ceramics with the low melting point. Anisotropic ceramics-bonded (15 vol%) Nd-Fe-B-type magnet had remarkably enhanced electrical resistivity (similar to 730 mu Omega.cm) with respect to the magnet without ceramics binder (similar to 220 mu Omega.cm). Thanks to lowtemperature consolidation of Nd-Fe-B-type particles using oxide ceramic binder with low melting point, the detrimental reaction between the magnetic particle surface and oxide was profoundly suppressed, thus retaining the high coercivity of initial magnetic particles even in the ceramics-bonded magnets. Ceramics-bonded (15 vol%) magnet, which had good room temperature magnetic performance (H-i(c) = 12.7 kOe, M-r = 9.4 kG, and (BH)(max) = 17.0 MGOe) still had reasonably good performance [H-i(c) = 5.0 kOe, M-r = 8.7 kG, and (BH)(max) = 10.2 MGOe] at 150 degrees C.

The synthesis of platinum silicide at a Pt/SiOx interface by photon irradiation was investigated using transmission electron microscopy. A platinum silicide, Pt2Si, was successfully formed at the Pt/SiOx interface by irradiation with 680 and 140 eV photons, but not by irradiation with 80 eV photons. Silicide formation was also induced by irradiation with electrons of energy 75 keV. The amount of silicide formed by photon irradiation was lower than the amount obtained by electron irradiation. Silicide formation by both photon and electron irradiation was accompanied by Si depletion in amorphous SiOx. The experimental results indicate that silicide formation is induced by electronic excitation. A possible mechanism for silicide formation is proposed on the basis of the results. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Variation of intrinsic coercivity of the HDDR-treated Nd12.5Fe80.8B6.4Ga0.3 alloy after heating in various modes was investigated. Influence of vacuum degree and cooling after heating on the coercivity of the HDDR material was examined. The heat-treated HDDR material had consistently higher coercivity when it was quenched after heating compared to when slow-cooled. Higher coercivity in the quenched material was attributable to the grain boundary with lower Fe content. HDDR-treated material heated in high vacuum showed consistently higher coercivity than the material heated in lower vacuum, and this was attributed to less heavily oxidized surface. Reduced coercivity of the HDDR-treated material heated at moderate temperature was noticeably recovered at higher temperature, and this was attributed to lower Fe content in the grain boundary.

Optical properties of nucleobase thin films were studied by attenuated total reflection (ATR) and surface-enhanced Raman spectroscopy (SERS). Adenine and guanine films were deposited on fused silica and silver at room temperature by thermal evaporation, and the normal dispersion of refractive indices of transparent adenine and guanine films in the visible and near-infrared regions were analyzed. The measured ATR spectra of adenine (guanine) films and numerical simulations by optical transfer matrix formalism demonstrate that the shift of surface plasmon resonance (SPR) wavelength is approximately linearly proportional to the adenine (guanine) film thickness, indicating that SPR can be used for quantitative measurements of biomaterials. The Raman spectra indicated that the adenine (guanine) films can be deposited by thermal evaporation. The adenine (guanine) films on silver exhibited Raman intensity enhancement as compared to those on glass, which was attributed to the SPR effect of silver platform and might play a role as a hot plate for SERS detection of biomaterials.

Two types of re-substituted (FeCo)2B-type alloys with stoichiometric (Fe0.675Co0.3Re0.025)2B and 1.5 at% boron-excess compositions were prepared by suction casting and subsequent mechanical milling and annealing. Phase evolution in the (FeCo)2B-type alloys in the course of mechanical milling and annealing was investigated. Single-phase re-substituted (FeCo)2B-type material was prepared from stoichiometric (Fe0.675Co0.3Re0.025)2B by the combination of suction casting and mechanical milling. The two alloys had the same phase constitution of (Fe, Co)2B-type and amorphous phases in heavily milled state. However, the heavily milled alloys had different phase constitution after annealing; the stoichiometric alloy consisted of single (Fe, Co)2B-type phase, while the boron-excess alloy consisted of two-phase mixture of (Fe, Co)2B-type and (Fe, Co)B-type phases. The two heavily milled alloys had similar coercivity of around 1 kOe after full annealing.

Ceramics-bonded magnet with remarkably high electrical resistivity was fabricated by hot-pressing the mixture of Nd13.6Fe73.6Co6.6Ga0.6B5.6 alloy melt-spun flakes and dielectric Bi2O3-SiO2-B2O3 ceramics powder with low melting point. Coercivity of the ceramics-bonded magnet decreased with increasing the addition of ceramics binder, and this was attributed to the increased demagnetizing factor. Thin oxidized layer on the flake surface formed by reaction between the flake and oxide binder also contributed to reducing coercivity in the ceramics-bonded magnet. Highly resistive ceramics-bonded magnet containing 30 vol% ceramics binder still had good magnetic performance and high mechanical strength at 175 oC: iHc = 5 kOe, Mr = 4.8 kG, (BH)max = 4.3 MGOe, and over 900 MPa.

To better understand the function of the red pigment in Cordyceps pruinosa, its effects on the cellular response of fungal spores to plasma-generated reactive oxygen species were studied. It is known that the degree of pigmentation in fungi is affected by environmental factors such as light exposure. C. pruinosa produced a red pigment when it grew in the light condition, but produced no pigment in the dark condition. An atmospheric-pressure plasma jet (APPJ) was used to generate reactive oxygen and nitrogen species in aqueous solution. Exposure of C. pruinosa spores to the APPJ decreased their viability in a time-dependent manner. For the same plasma treatment times, viability of spores was higher for light condition-grown C. pruinosa (LCP) than for dark-grown C. pruinosa (DCP). Moreover, analysis of oxygen radical scavenging activity in the ethanol extracts of LCP and DCP revealed that the higher spore viability of LCP could be attributed to the red pigment in the fungus. Induced circular dichroism revealed that the red pigment was embedded in the cell wall matrix. Liquid-chromatography and mass-spectroscopy results showed that the red pigment in C. pruinosa contains a compound with a molecular weight of 570 and its oxidation products. Overall, this study shows that the red pigment in C. pruinosa protects its spores from reactive species generated from the plasma itself and those derived from reaction of plasma radicals with the aqueous solution.