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OBJECTIVE: The purpose of this study was to determine the bond stability and the change in interfacial ultra-structure of a conventional glass-ionomer cement bonded to dentin, with and without pre-treatment using a polyalkenoic acid conditioner. METHODS: The occlusal dentin surfaces of six teeth were ground flat. Glass-ionomer cement was bonded to the surfaces either with or without polyalkenoic acid conditioning. The teeth were sectioned into 1-mm2 stick-shaped specimens. The specimens obtained were randomly assigned to two groups with different periods of storage in water: 1 week and 1 year. The micro-tensile bond strength (μTBS) was determined for each storage time. Additional specimens were prepared for Transmission Electron Microscopy (TEM); they were produced with or without prior polyalkenoic acid conditioning in the same way as in the μTBS test. RESULTS: There was no significant difference in μTBS to conditioned dentin and non-conditioned dentin (p > 0.05). The failures appeared to be of a mixed nature, although aging caused more areas of cohesive than adhesive failure in both groups. The TEM observation showed an intermediate layer, a matrix-rich layer and a partially demineralized layer in the polyalkenoic acid conditioned group. SIGNIFICANCE: Aging did not reduce the bond strength of the conventional glass-ionomer cement to dentin with or without the use of a polyalkenoic acid conditioner. ispartof: DENTAL MATERIALS vol:37 issue:1 pages:106-112 ispartof: location:England status: published

This work demonstrates that certain medically-approved drugs possess dual functions such that they exhibit intrinsic drug effects and can assist in dispersing carbon nanomaterials. Two types of carbon nanohorns (CNHs) (unoxidized: as-CNH, oxidized: CNHox550) and carbon nanotubes (CNTs) were successfully dispersed in aqueous solutions using minocycline (MC) as a dispersant. Absorption spectra, thermogravimetric analyses and theoretical calculations demonstrated that the MC was attached to the CNHs in these dispersions. The antibacterial activities of these MC/CNH complexes were examined using Streptcoccus mutans and Aggregatibacter actinomycetemcomitans, and the MC/as-CNH complex was found to maintain the same bacterial growth inhibition activity as the original MC. Electron microscopy observations suggested direct contact of the MC/CNH complexes with the bacteria, presumably allowing delivery of the MC. The results obtained from our study demonstrate that drug/nanocarbon complexes have potential applications in drug delivery.

One promising way to reduce the use of noble metal catalysts is to use extremely fine particle catalysts, such as subnanoclusters and single-atom catalysts. For practical use, suppression of diffusion and agglomeration of catalysts are needed. Heteroatom-doped graphene, which has high specific surface area, high chemical and mechanical stabilities, high electrical and thermal conductivities, and contains anchoring sites for catalysts, is promising catalyst support. Heteroatom-doped graphene can widely control the support effects. This review summarizes recent dopant structure characterization using spectroscopy and density functional theory calculations. The distribution of highly-dispersed metal catalysts and their diffusion properties are discussed. In addition, The effects of environmental conditions on catalyst dynamic behaviors are introduced. Finally, the outlook of heteroatom-doped graphene and new two-dimensional material supports is discussed.

Localized surface plasmon resonance (LSPR) in a silver (Ag) nanosphere dimer embedded in silicate glass was investigated using scanning transmission electron microscopy electron energy-loss spectro...

Carbon nanomaterials (CNMs) are used in various functional materials and products as well as in basic research, predominantly in engineering. Because of their high biocompatibility, use of CNMs in bioapplications is widely anticipated. Many researchers have examined the kinetics and toxicity of intravenously administered CNMs. However, little research on the in vivo kinetics of locally implanted CNMs has been reported. In this study, single-walled carbon nanotubes (SWCNTs) were implanted between the periosteum and parietal bone of mice. The in vivo kinetics of the implanted SWCNTs were observed by near-infrared (NIR) fluorescence imaging (excitation wavelength, 730 nm; emission wavelength, >1000 nm), because the body is highly transparent to light in the NIR region, and autofluorescence in this region is low, making NIR fluorescence suitable for bioimaging. SWCNTs were visible in the subcutaneous tissue and medullary cavity. Fluorescence was observed in the cranial region, and its intensity gradually decr...

NH3-SCR (selective catalytic reduction) is important process for removal of NOx. However, water vapor included in exhaust gases critically inhibits the reaction in a low temperature range. Here, we report bulk W-substituted vanadium oxide catalysts for NH3-SCR at a low temperature (100–150 °C) and in the presence of water (~20 vol%). The 3.5 mol% W-substituted vanadium oxide shows >99% (dry) and ~93% (wet, 5–20 vol% water) NO conversion at 150 °C (250 ppm NO, 250 ppm NH3, 4% O2, SV = 40000 mL h−1 gcat−1). Lewis acid sites of W-substituted vanadium oxide are converted to Brønsted acid sites under a wet condition while the distribution of Brønsted and Lewis acid sites does not change without tungsten. NH4+ species adsorbed on Brønsted acid sites react with NO accompanied by the reduction of V5+ sites at 150 °C. The high redox ability and reactivity of Brønsted acid sites are observed for bulk W-substituted vanadium oxide at a low temperature in the presence of water, and thus the catalytic cycle is less affected by water vapor., NH3 selective catalytic reduction is an important technique for NOx removal but water vapor critically inhibits the reaction at a low temperature. Here the authors show bulk W-substituted VOx exhibits higher NOx removal ability than the TiO2 supported vanadia catalyst in the presence of water.

Gold nanoparticles were fabricated on an ordered aluminum dimple array via aluminum anodizing, sputter coating, and thermal treatment, and the transformation behavior and nanostructural characterization were investigated in detail. Electropolished aluminum specimens were anodized in an oxalic acid solution under self-ordering conditions at 40 V, and then the porous alumina was selectively dissolved to expose an ordered aluminum dimple array with each dimple measuring 100 nm. A thin layer of gold was coated onto the dimple array, and a thermal treatment was subsequently performed. The gold layer was transformed into numerous particles by the thermal treatment due to dewetting. When the values of gold layer thickness, thermal treatment temperature, and thermal treatment duration were optimized, the gold particles were located at the bottom of each aluminum dimple. Consequently, multiply-twinned particles with polygonal and elliptical shapes were regularly distributed on the aluminum dimple array treated at 473 K. Although the rate of the transformation induced by dewetting increased with the temperature of the thermal treatment, non-uniform gold nanostructures were formed by extended thermal treatment at 873 K. The gold particles formed on the aluminum surface exhibited excellent adhesion upon ultrasonication.

In this study, we calculated the diffusion of an Fe atom on graphene and various light-element (B, N, O, Si, P, and S)-doped graphene supports, using first-principles calculations based on density functional theory. We focused on dopants that could suppress the detachment and diffusion of an Fe atom. Such doped graphene supports would have strong potential in high-durability fuel cell catalysts and hydrogen storage materials. The Fe atom adsorbs on pristine graphene via ionic bonding. The bonding between the Fe atom and pristine graphene is very weak, and it has a low adsorption energy of −0.61 eV. Doped graphene contains unoccupied localized orbitals. B-, O-, Si-, and P-doped graphene show high adsorption energies of −1.70 eV, −2.70 eV, −1.46 eV, and −1.38 eV, respectively. Thus, these graphene supports could suppress the detachment of Fe nanoclusters and nanoparticles. We demonstrate that these doped graphene supports with high adsorption energies also have high diffusion barriers, which suppresses the agglomeration of Fe nanoclusters and nanoparticles. We conclude that B-, O-, Si-, and P-doped graphene are promising supports for enhancing the adsorption lifetime of Fe nanoclusters and nanoparticles. [DOI: 10.1380/ejssnt.2018.193]

Cerium-doped yttrium aluminum garnet (YAG:Ce) as a yellow phosphor for white light-emitting diodes (LEDs) was synthesized via a facile combustion method using Y2O3, CeO2, Al2O3, Al, and NaClO4 as raw materials. The combustion synthesis approach utilizes the strong exothermic oxidation of aluminum to realize a self-sustaining reaction. In this study, we investigated the effects of the ratios of Al2O3 to Al, fluxes, and coprecipitated materials as raw materials on the luminescence properties of the synthesized YAG:Ce phosphors. When the amount of Al2O3 x is varied, the combustion reaction proceeds at x

Yellow Ca-α-SiAlON:Eu 2+ phosphors for white light-emitting diodes (LEDs) were synthesized by a facile combustion synthesis method using CaO, Eu 2 O 3 , α-Si 3 N 4 , Si, and Al as raw materials. Ca concentrations and diluent ratios were optimized to improve their luminescence properties. The lattice constant and luminescence properties improved as x increased from 0.4 to 1.2 in Ca x Si 12 − (m+n) Al m+n O n N 16−n :Eu 0.06 . The optimum value was x = 1.2. Scanning transmission electron microscopy combined with energy dispersive X-ray analysis detected segregation of Ca and Eu at grain boundaries, which decreased luminescence behavior in the x = 1.4 sample. The influence of Si and Si 3 N 4 diluents was investigated by varying the diluent ratio φ = (CaO + Eu 2 O 3 + α-Si 3 N 4 )/(CaO + Eu 2 O 3 + α-Si 3 N 4 + Al + Si). Changes in temperature and flame propagation speed were measured during combustion synthesis using two thermocouples. When φ was less than 0.5, the combustion temperature exceeded 1600 °C and the synthesized material contained an amount of the high-temperature β-SiAlON phase. At φ > 0.7, the reaction temperature fell below 1200 °C, and unreacted raw materials remained. The optimum value of φ was 0.6. The internal quantum efficiency of the product synthesized at x = 1.2 and φ = 0.6 was approximately 35% under 450-nm excitation. According to electron probe X-ray microanalysis, composition varied within individual synthesized particles, which may explain the decrease in emission behavior relative to a commercial product.

Light-element-doped graphene is a promising support for polymer electrode fuel cell electrode catalysts. To understand the behavior of catalyst atoms on light-element-doped graphene, we investigated the adsorption states and diffusion behavior of a single Pt atom on pristine graphene and B-, N-, O-, Si-, P-, and S-doped graphene by first-principles calculations based on density functional theory. We found that localized orbitals, which can trap Pt atoms, are created in the vicinity of dopants. Thus, these doped graphene supports prevent Pt atom desorption. In particular, O- and P-doped graphene showed adsorption energies of −3.93 and −3.59 eV, respectively, while that of pristine graphene is −1.45 eV. We also calculated the diffusion coefficients of Pt atoms on these doped graphene at 100 °C, which is a typical operating temperature of polymer electrode fuel cells. The obtained diffusion coefficients of Pt atoms on doped graphene were less than that on pristine graphene. The diffusion coefficient on P-dop...

Three-dimensional (3D) distributional analysis of individual dopant atoms in materials is important to development of optical, electronic, and magnetic materials. In this study, we adopted through-focus high-angle annular dark-field (HAADF) imaging for 3D distributional analysis of Eu dopant atoms in Ca-α-SiAlON phosphors. In this context, the effects of convergence semi-angle and Eu z-position on the HAADF image contrast were investigated. Multi-slice image simulation revealed that the contrast of the dopant site was sensitive to change of the defocus level. When the defocus level matched the depth position of a Eu atom, the contrast intensity was significantly increased. The large convergence semi-angle greatly increased the depth resolution because the electron beam tends spread instead of channeling along the atomic columns. Through-focus HAADF-STEM imaging was used to analyze the Eu atom distribution surrounding 10nm cubes with defocus steps of 0.68nm each. The contrast depth profile recorded with a narrow step width clearly analyzed the possible depth positions of Eu atoms. The radial distribution function obtained for the Eu dopants was analyzed using an atomic distribution model that was based on the assumption of random distribution. The result suggested that the Ca concentration did not affect the Eu distribution. The decreased fraction of neighboring Eu atoms along z-direction might be caused by the enhanced short-range Coulomb-like repulsive forces along the z-direction.

We investigated the H and H2 adsorption effects on the stability of a Pt atom on various heteroatom-doped graphene supports using first-principles calculations based on density functional theory. We show that H and H2 adsorptions on the Pt atom weaken the interaction between the Pt atom and graphene support and decrease the adsorption energy of Pt atoms. H2 adsorption on Pt atoms decreases the adsorption energy of Pt atoms on all graphene supports by more than 30%, whereas H adsorption only affects pristine, O-, and S-doped graphene. These results indicate that the hydrogen atmosphere enhances the detachment of Pt catalysts. However, the B-, O-, Si-, P-doped, and monovacant graphene still maintained large adsorption energies of PtH and PtH2 of more than 1.5 eV. In addition, the diffusion barriers of PtH and PtH2 on pristine graphene were calculated to be less than 0.07 eV, which further demonstrated that H and H2 enhance the degradation of Pt catalysts. Even after H and H2 adsorptions on a Pt atom, O-, Si-, P-doped, and monovacant graphene still maintained large diffusion barriers of more than 1 eV. Therefore, we concluded that O-, Si-, and P-doped graphene are suitable supports for Pt catalysts in a hydrogen atmosphere.

Because abnormal grain growth (AGG) degrades mechanical properties of industrial polycrystalline materials such as steel, understanding and controlling AGG are important. In this study, AGG of Al-Nb-microalloyed low-carbon steel was investigated at 1100°C using in-situ scanning electron microscopy-electron backscatter diffraction (SEM-EBSD). Owing to the pinning particles of AlN and Nb(C,N), fine austenite grains formed initially, and AGG appeared owing to the dissolution of the pinning particles at high temperatures. Relatively large grains invaded the surrounding smaller grains with a size ratio of approximately 0.3, resulting in AGG. We developed the in-situ observation method to investigate the AGG of the carburization process using a diffusion couple of high- and low-carbon steels. The carbon diffusion into the low-carbon steel from the high-carbon steel enhanced the grain growth of the low-carbon steel. Although the detailed mechanism is still unclear, we clearly showed that carburization can reduce the pinning force. When focusing on the misorientation of the grain boundary, grain boundaries with misorientation angles of 50–59° remained during AGG, which is explained by their lower mobility owing to their lower grain boundary energy. These results suggest that the difference in grain-boundary mobility can induce duplex grain growth with a bimodal distribution, resulting in AGG.

We investigated the atomic and local electronic structures of Ca2AlMnO5+δ to assess its potential as an oxygen storage material. High-angle annular dark-field scanning transmission electron microscopy was used to investigate structural changes in the material during oxygen storage. We found that the AlO4 tetrahedra convert to AlO6 octahedra during such a process. According to the Mn L-edge electron energy-loss near-edge structure (ELNES) measurements, the Mn oxidation state increased from +3 to +4 on oxygen storage. The observed site-resolved oxygen K-ELNES and first-principles electronic structure calculations showed that each nonequivalent oxygen site has different characteristics, corresponding to local chemical bonding and oxygen intake and release. For Ca2AlMnO5, the prepeak intensity was higher at MnO6 octahedral sites, indicating covalent bonding between the oxygen and Mn atoms. After oxygen storage, the ELNES spectra revealed that the Jahn–Teller distortion of the Mn sites was suppressed by the in...

Twin formation in hematite during dehydration was investigated using X-ray diffraction, electron diffraction, and high-resolution transmission electron microscopy (TEM). When synthetic goethite was heated at different temperatures between 100 and 800 °C, a phase transformation occurred at temperatures above 250 °C. The electron diffraction patterns showed that the single-crystalline goethite with a growth direction of [001]G was transformed into hematite with a growth direction of [100]H. Two non-equivalent structures emerged in hematite after dehydration, with twin boundaries at the interface between the two variants. As the temperature was increased, crystal growth occurred. At 800 °C, the majority of the twin boundaries disappeared; however, some hematite particles remained in the twinned variant. The electron diffraction patterns and high-resolution TEM observations indicated that the twin boundaries consisted of crystallographically equivalent prismatic (100) (010), and (1 $$\bar{1}$$ 0) planes. According to the total energy calculations based on spin-polarized density functional theory, the twin boundary of prismatic (100) screw had small interfacial energy (0.24 J/m2). Owing to this low interfacial energy, the prismatic (100) screw interface remained after higher-temperature treatment at 800 °C.

In this study, Ca-α-SiAlON:Eu2+ yellow phosphors for white light-emitting diodes (LEDs) were synthesized via a facile combustion synthesis method by using CaO, Eu2O3, Si, and Al as raw materials, while NaCl and Si3N4 were utilized as diluents to contain the combustion temperature. The concentration of Eu was varied, and the resulting changes in phase purity, photoluminescence properties, and thermal quenching were investigated. We observed that the increase in lattice constant depended on the amount of Al, while the Ca sites were partially substituted by Eu ions. The synthesized Ca-α-SiAlON:Eu2+ powders exhibited emission wavelength at 556–560 nm and high thermal stability, revealing high potential for application in white LEDs.

We investigated an improved Kramers-Kronig analysis (KKA) routine for measuring the dielectric function of alpha-Al2O3, avoiding the retardation effect arising in electron energy-loss spectroscopy (EELS). The EELS data differed from the optical data in the energy range of 10-20 eV due to the retardation effect, even though Cerenkov loss was thoroughly suppressed. The calculated differential cross-section indicates that the influence of the retardation appears at scattering angles less than 0.2 mrad in the loss energy range of 10-15 eV. Using the improved KKA routine, we obtained the correct dielectric function that agreed with the optical data. The present technique is especially useful in measuring the dielectric function by EELS with a small collection semi-angle.

This study optimizes the dehydration temperature of goethite to control pore morphology. The pore morphology was characterized by using transmission electron microscopy and the nitrogen adsorption method. When the goethite was dehydrated at 200–250°C, slit-like pores with a width lesser than 2 nm were formed along the [010] direction. These slit-like pores changed to spherical micropores (300–500°C), and eventually disappeared (600–800°C). Compared to the synthetic goethite, natural goethite has a lower crystallinity and smaller primary particle size of under 100 nm. The natural goethite before dehydration contained 4 nm pores as cracks that remained even after heating to 800°C. In the case of natural goethite, the optimum dehydration temperature for higher surface area and pore volume was 350°C, which was higher than that of 250°C for the synthetic goethite.

In this study, a Sn–C composite material as anode material for lithium ion batteries was fabricated via MgO template-assisted solution combustion synthesis, in which the starting material was a gel containing Sn(NO 3 ) 2 , glycine (C 2 H 5 O 2 N) as the carbon source, and Mg(NO 3 ) 2 ·6H 2 O for the template. After the combustion reaction, the generated MgO was removed from the carbon, and the Sn nanoparticles were dispersed into a porous carbon structure during the carbon reduction of SnO 2 under calcination in N 2 . The effects of ratios of glycine ( n ) and MgO ( m ) on the material phase, morphology, carbon content, and electrochemical properties were mainly investigated. At glycine ( n ) ratios of 2 and 3, the SnO 2 phase was not fully reduced to Sn. With n > 3, a composite material of metallic Sn nanoparticles and carbon was synthesized, in which the ratio of carbon increased with increasing n . With increasing m , the porosity of the particles increased, resulting in enhanced cyclic stability owing to the buffer space provided by the porous structure of carbon. The composite material obtained at n = 4 and m = 4 exhibited the highest reversible capacity of 588 mA h/g after 100 discharge/charge cycles at a current rate of 0.5 A/g as compared to the 269 mA h/g observed for n = 4 and m = 2.

Self-ordered periodic porous alumina with an undiscovered cell diameter was fabricated via electrochemical anodizing in a new electrolyte, phosphonic acid (H3PO3). High-purity aluminum plates were anodized in phosphonic acid solution under various operating conditions of voltage, temperature, concentration, and anodizing time. Phosphonic acid anodizing at 150–180 V caused the self-ordering behavior of porous alumina, and an ideal honeycomb nanostructure measuring 370–440 nm in cell diameter was successfully fabricated on the aluminum substrate. Conversely, disordered porous alumina grew at below 140 V, and anodizing at above 190 V caused local thickening due to oxide burning. Two-step phosphonic acid anodizing allows the fabrication of high aspect ratio ordered porous alumina. HPO32− anions originated from the electrolyte were incorporated into the porous oxide during anodizing. Consequently, a double-layered porous alumina consisting of a thick outer layer containing incorporated HPO32− anions, and a thin inner layer without anions was constructed via phosphonic acid anodizing.

Brownmillerite-structured Ca2AlMnO5 is inexpensive and capable of rapid oxygen storage and release. This study focused on improving the oxygen storage/release rate of Ca2AlMnO5, which is essential for its application in practical oxygen production systems. Two approaches were investigated for improving the oxygen-trapping ability of Ca2AlMnO5: heat treatment for 2 h and 24 h after solution combustion synthesis (SCS) and the addition of Pt nanoparticles as a catalyst. Noticeably, crystalline Ca2AlMnO5 was formed after heat treatment at 1250 °C for at least 2 h. For the 2-h heat treatment, the average particle size of Ca2AlMnO5 was 11.4 μm, while that for the 24-h treatment was 18.9 μm. This reduction in the particle size increases the oxygen storage/release rate because of the relatively short diffusion distance within the particles. The oxygen storage rate increased with the addition of Pt nanoparticles because the nanoparticles were distributed across the surface and acted as catalyst. This catalyst accelerated the oxygen-evolution reaction by activating the surface reactions between oxygen ions and the Ca2AlMnO5 particles. The short 2-h heat treatment prevented the Pt nanoparticles from aggregating. When the Pt nanoparticle addition was implemented in combination with the 2-h heat treatment, the storage and release rates were drastically improved, i.e., by 2.5 and 6.1 times, respectively, compared with the sample after 24-h heat treatment without Pt nanoparticles. The oxygen storage/release rate remained constant even after repeated use at 550 °C, for over 25 cycles. Furthermore, Ca2AlMnO5 suffered no surface damage, and none of the Pt nanoparticles re-agglomerated after this test, further indicating the durability of the treated material.

The absorption states of hydrogen isotopes in various ceramic materials were investigated by density functional theory. For pristine ceramic materials, main-group oxides do not form any bond with a hydrogen atom. However, transition metal oxides form hydroxyl groups and absorb hydrogen atoms. Main-group and transition metal nitrides form ionic bonds between a hydrogen atom and the surrounded cation. For anion-deficient ceramic materials, hydrogen atoms are negatively charged because of excess electrons induced by anion vacancies, and ionic bonds form with the surrounded cation, which stabilizes the hydrogen absorption state. N substitutional doping into oxides introduces an electron hole, while O substitutional doping into the nitrides introduces an excess of electrons. Therefore, hydrogen isotopes form covalent bonds in N-substituted oxides, and form hydride ions in O-substituted nitrides. Thus, Al2 O3 , SiO2 , CrN, and TiN are promising materials as hydrogen permeation barriers.

In this paper, we describe the glycine–nitrate-based solution combustion synthesis of SrTiO3 nanoparticles. The effects of the fuel ratio, φ, and washing treatment by HNO3 on the size, morphology, and crystalline structure of the synthesized particles were investigated. The photocatalytic activity of the final samples was also evaluated by measuring the photodegradation of methylene blue. The samples, which were calcined at 1000 °C for 10 h after combustion synthesis, were mainly SrTiO3. When φ was increased, the number of pores in the sample was increased because of the increase in volume of ejected gas. Additionally, the initial particle size decreased with increasing φ because glycine functioned not only as a fuel but also as a dispersant and stabilizer. After washing in a HNO3 solution, the porous structure decomposed to particles with high crystalline structure. The photocatalytic activity of SrTiO3 was significantly improved by HNO3 washing owing to the elimination of impurities, the increase in surface area, and the uncovering of the surface that consisted of (100) planes.

The formation behavior of anodic alumina nanofibers via anodizing in a concentrated pyrophosphoric acid under various conditions was investigated using electrochemical measurements and SEM/TEM observations. Pyrophosphoric acid anodizing at 293 K resulted in the formation of numerous anodic alumina nanofibers on an aluminum substrate through a thin barrier oxide and honeycomb oxide with narrow walls. However, long-term anodizing led to the chemical dissolution of the alumina nanofibers. The density of the anodic alumina nanofibers decreased as the applied voltage increased in the 10–75 V range. However, active electrochemical dissolution of the aluminum substrate occurred at a higher voltage of 90 V. Low temperature anodizing at 273 K resulted in the formation of long alumina nanofibers measuring several micrometers in length, even though a long processing time was required due to the low current density during the low temperature anodizing. In contrast, high temperature anodizing easily resulted in the formation and chemical dissolution of alumina nanofibers. The structural nanofeatures of the anodic alumina nanofibers were controlled by choosing of the appropriate electrochemical conditions, and numerous high-aspect-ratio alumina nanofibers (>100) can be successfully fabricated. The anodic alumina nanofibers consisted of a pure amorphous aluminum oxide without anions from the employed electrolyte.

A convenient method for coating titanium dioxide (TiO 2 ) by Au nanoparticles (AuNPs) is demonstrated in solution plasma to improve the photocatalytic activity of TiO 2 . AuNPs from a metallic Au electrode were bonded to the surface of a commercial TiO 2 powder, which acted as a catalyst support, with the reaction taking place in an electrolyte solution. The effect of diverse plasma conditions on the size and productivity of the AuNPs was investigated initially to provide a reference in the absence of TiO 2 . At 290 V, “ partial plasma ” was attained, with only a weak light emission surrounding the Au electrode. Conditions then evolved to “ full plasma ”, with a strong orange emission at 330 V. Partial or full status was maintained for 1 h at 300 and 400 V, respectively. At the transition to full, the AuNP particle size increased from 3.72 to 6.09 nm and the productivity increased dramatically from 0.025 to 0.87 mg h − 1 mm − 2 . Stronger plasma very efficiently synthesized AuNPs, and therefore, it was adopted for further study. AuNP–TiO 2 combinations were formed by applying 400 V to a TiO 2 -dispersed solution. In these experiments, TiO 2 coated with AuNPs was synthesized; these combinations of AuNP–TiO 2 had 0.44 mol% of Au. The photocatalytic activity of AuNP–TiO 2 was investigated by measuring the degradation of Rhodamine B (RhB). Under UV irradiation, the AuNP–TiO 2 particles removed up to 95% of the dye in 70 min. Commercial TiO 2 achieves values closer to 85%. The results thus raise the possibility that solution plasma methods can be generalized as a means for achieving catalysis-enhancing coatings.

Irradiation-induced void denuded zone (VDZ) formation near grain boundaries was studied to clarify the effects of minor alloying elements on vacancy diffusivity during irradiation in practical PNC316 stainless steel developed for nuclear reactor core materials. The test materials were Fe–15Cr–15Ni steel without additives and PNC316 stainless steel; the latter contains minor alloying elements to improve the void swelling resistance. These steels were neutron-irradiated in the experimental fast reactor JOYO at temperatures from 749 K to 775 K and fast neutron doses of 18–103 dpa, and electron irradiation was also carried out using 1 MeV high voltage electron microscopy at temperatures of 723 K and 773 K and doses up to 14.4 dpa. VDZ formation was analyzed by TEM microstructural observation after irradiation by considering radiation-induced segregation near the grain boundaries. VDZs were formed near random grain boundaries with higher misfit angles in both Fe–15Cr–15Ni and PNC316 steels. The VDZ widths in the PNC316 stainless steel were narrower than those for the Fe–15Cr–15Ni steel for all neutron and electron irradiations. The VDZ width analysis implied that the vacancy diffusivity was reduced in PNC316 stainless steel as a result of interaction of vacancies with minor alloying elements.