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Aldol reactions (self- and cross-aldol condensations) for conjugated enone synthesis were efficiently performed on large-sized Cs⁺ single sites (1 wt %) confined in β-zeolite channels in toluene, which showed the highest level of catalytic aldol condensation activity among reported zeolite catalysts. In general, aldol condensation reactions for C–C bond synthesis can proceed by acids (e.g., H⁺), bases (e.g., OH⁻), enolate species, and acidic or basic solid catalysts. However, the Cs⁺ single site/β sample without significant acid–base property showed unprecedented, efficient, and reusable catalysis for self-aldol and cross-aldol condensations. Intrinsically inactive Cs⁺ single sites due to the noble-gas electronic structure were transformed to active Cs⁺ single sites in β-zeolite channels. Cs⁺/β has many advantages such as broad substrate scope, eco-friendliness, high product selectivity and yield, and simple work-up procedure. Thus, the Cs⁺ single site/β provides an attractive and useful methodology for practical C–C bond synthesis. On the basis of the Cs⁺/β characterization by X-ray photoelectron spectroscopy (XPS), in situ X-ray absorption fine structure (XAFS) (X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS)), and temperature-programmed desorption (TPD), density functional theory (DFT) calculations of the self- and cross-aldol condensation reaction pathways involving the transition states on the Cs⁺ single site in β-zeolite channel revealed nontraditional concerted interligand bond rearrangement mechanisms.

There is little information on the spatial distribution, migration, and valence of Ce species doped as an efficient radical scavenger in a practical polymer electrolyte fuel cell (PEFC) for commercial fuel cell vehicles (FCVs) closely related to a severe reliability issue for long-term PEFC operation. An in situ three-dimensional fluorescence computed tomography–X-ray absorption fine structure (CT–XAFS) imaging technique and an in situ same-view nano-XAFS–scanning electron microscopy (SEM)/energy-dispersive spectrometry (EDS) combination technique were applied for the first time to perform operando spatial visualization and depth-profiling analysis of Ce radical scavengers in a practical PEFC of Toyota MIRAI FCV under PEFC operating conditions. Using these in situ techniques, we successfully visualized and analyzed the domain, density, valence, and migration of Ce scavengers that were heterogeneously distributed in the components of PEFC, such as anode microporous layer, anode catalyst layer, polymer electrolyte membrane (PEM), cathode catalyst layer, and cathode microporous layer. The average Ce valence states in the whole PEFC and PEM were 3.9+ and 3.4+, respectively, and the Ce³⁺/Ce⁴⁺ ratios in the PEM under H₂ (anode)–N₂ (cathode) at an open-circuit voltage (OCV), H₂–air at 0.2 A cm⁻², and H₂–air at 0.0 A cm⁻² were 70 ± 5:30 ± 5%, as estimated by both in situ fluorescence CT–X-ray absorption near-edge spectroscopy (XANES) and nano-XANES–SEM/EDS techniques. The Ce³⁺ migration rates in the electrolyte membrane toward the anode and cathode electrodes ranged from 0.3 to 3.8 μm h⁻¹, depending on the PEFC operating conditions. Faster Ce³⁺ migration was not observed with voltage transient response processes by highly time-resolved (100 ms) and spatially resolved (200 nm) nano-XANES imaging. Ce³⁺ ions were suggested to be coordinated with both Nafion sulfonate (Nf_sul) groups and water to form [Ce(Nf_sul)_x(H₂O)_y]³⁺. The Ce migration behavior may also be affected by the spatial density of Ce, interactions of Ce with Nafion, thickness and states of the PEM, and H₂O convection, in addition to the PEFC operating conditions. The unprecedented operando imaging of Ce radical scavengers in the practical PEFCs by both in situ three-dimensional (3D) fluorescence CT–XAFS imaging and in situ depth-profiling nano-XAFS–SEM/EDS techniques yields intriguing insights into the spatial distribution, chemical states, and behavior of Ce scavengers under the working conditions for the development of next-generation PEFCs with high long-term reliability and durability.

Aims Intraductal tubulopapillary neoplasm (ITPN) of the pancreas is a recently recognized pancreatic tumor entity. Here we aimed to determine the most important features with a systematic review coupled with an integrated statistical approach. Methods and results PubMed, SCOPUS, and Embase were searched for studies reporting data on pancreatic ITPN. The clinicopathological, immunohistochemical, and molecular data were summarized. Then a comprehensive survival analysis and a comparative analysis of the molecular alterations of ITPN with those of pancreatic ductal adenocarcinoma (PDAC) and intraductal papillary mucinous neoplasm (IPMN) from reference cohorts (including the International Cancer Genome Consortium- ICGC dataset and The Cancer Genome Atlas, TCGA program) were conducted. The core findings of 128 patients were as follows: (i) Clinicopathological parameters: pancreatic head is the most common site; presence of an associated adenocarcinoma was reported in 60% of cases, but with rare nodal metastasis. (ii) Immunohistochemistry: MUC1 (>90%) and MUC6 (70%) were the most frequently expressed mucins. ITPN lacked the intestinal marker MUC2; unlike IPMN, it did not express MUC5AC. (iii) Molecular landscape: Compared with PDAC/IPMN, the classic pancreatic drivers KRAS, TP53, CDKN2A, SMAD4, GNAS, and RNF43 were less altered in ITPN (P < 0.001), whereas MCL amplifications, FGFR2 fusions, and PI3KCA mutations were commonly altered (P < 0.001). (iv) Survival analysis: ITPN with a "pure" branch duct involvement showed the lowest risk of recurrence. Conclusion ITPN is a distinct pancreatic neoplasm with specific clinicopathological and molecular characteristics. Its recognition is fundamental for its clinical/prognostic implications and for the enrichment of potential targets for precision oncology.

We report the transformation of Cs+ ions with an inactive noble gas electronic structure to active Cs+ single sites chemically confined in Y zeolite pores (Cs+/Y), which provides an unprecedented catalysis for oxidative cyanation (ammoxidation) of Csp3–H bonds with O2 and NH3, although in general, alkali and alkaline earth metal ions without a moderate redox property cannot activate Csp3–H bonds. The Cs+/Y catalyst was proved to be highly efficient in the synthesis of aromatic nitriles with yields >90% in the selective ammoxidation of toluene and its derivatives as test reactions. The mechanisms for the genesis of active Cs+ single sites and the ammoxidation pathway of Csp3–H bonds were rationalized by density functional theory (DFT) simulations. The chemical confinement of large-sized Cs+ ions with the pore architecture of a Y zeolite supercage rendered the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap reduction, HOMO component change, and preferable coordination arrangement for the selective reaction promotion, which provides a trimolecular assembly platform to enable the coordination-promoted concerted ammoxidation pathway working closely on each Cs+ single site. The new reaction pathway without involvement of O2-dissociated O atom and lattice oxygen differs from the traditional redox catalysis mechanisms for the selective ammoxidation.

The doubly beneficial contribution of a nanoscale fabricated carbon surface and devised strong Pt-carbon interface to remarkable improvements of Pt/carbon fuel cell electrodes was evidenced to be a crucial clue for rational design of next-generation less-Pt/C electrodes. Real-world carbon surface morphology and metal-carbon interfaces are complex and interrelated and hard to control at a statistical level. Herein, we fabricated plasma-devised nanoneedles-glassy carbon (GC) from well-defined flat GC as model supports, on which Pt nanoparticles were anchored by arc plasma. The arc plasma deposited (APD)-Pt/flat-GC with a strong metal-support interface exhibited enhanced activity for the electrochemical oxygen reduction reaction (ORR) compared to chemically supported Pt/flat-GC and commercial Pt/C electrodes. The APD-Pt/nanoneedles-GC further promoted the ORR and showed a remarkable durability without significant deactivation after accelerated durability test cycles. The structural defects and compressive strain of Pt nanoparticles were induced by the plasma-devised metal-support contact, which may benefit the ORR activity of APD-Pt/nanoneedles-GC. The nanoneedles-GC support morphology may also improve oxygen gas transport at the nanoscale through modifying the hydrophobicity/hydrophilicity of the GC surface. These results on the devised Pt/C model electrodes reveal the highly enhanced activity and durability of the APD-Pt/nanoneedles-GC electrode by the doubly beneficial effects of a support nanoscale morphology and strong metal-support interface, which were characterized by the intimate combination of Pt/GC synthesis, electrochemical measurements, in situ XAFS, and HAADF-STEM. Our experimental findings provide necessary clues for the design and synthesis of active and durable fuel cell electrodes, metal-air batteries, and catalytic materials.

In order to obtain a suitable design policy for the development of a next-generation polymer electrolyte fuel cell, we performed a visualization analysis of Pt and Co species following aging and degradation processes in membrane-electrode assembly (MEA), using a same-view. Nano-X-ray absorption fine structure (XAFS)/Scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS) technique that we developed to elucidate durability factors and degradation mechanisms of a MEA Pt3Co/C cathode electrocatalyst with higher activity and durability than a MEA Pt/C. In the MEA Pt3Co/C, after 5000 ADT-rec (rectangle accelerated durability test) cycles, unlike the MEA Pt/C, there was no oxidation of Pt. In contrast, Co oxidized and dissolved over a wide range of the cathode layer (∼70% of the initial Co amount). The larger the size of the cracks and pores in the MEA Pt/C and the smaller the ratio of Pt/ionomer of cracks and pores, the faster the rate of catalyst degradation. In contrast, there was no correlation between the size or Co/ionomer ratio of the cracks and pores and the Co dissolution of the MEA Pt3Co/C. It was shown that Co dissolved in the electrolyte region had an octahedral Co2+–O6 structure, based on a 150 nm × 150 nm nano-XAFS analysis. It was also shown that its existence suppressed the oxidation and dissolution of Pt. The MEA Pt3Co/C after 10,000 ADT-rec cycles had many cracks and pores in the cathode electrocatalyst layer, and about 90% of Co had been dissolved and removed from the cathode layer. We discovered a metallic Pt–Co alloy band in the electrolyte region of 300–400 nm from the cathode edge and square planar Pt2+–O4 species and octahedral Co2+–O6 species in the area between the cathode edge and the Pt–Co band. The transition of Pt and Co chemical species in the Pt3Co/C cathode electrocatalyst in the MEA during the degradation process, as well as a fuel cell deterioration suppression process by Co were visualized for the first time at the nano scale using the same-view nano-XAFS/STEM-EDS combination technique that can measure the MEA under a humid N2 atmosphere while maintaining the working environment for a fuel cell.

Supported metals are widely used as industrial catalysts wherein the supports affect catalytic performances remarkably through either electronic and/or geometric interactions with the metals, and/or providing interfacial synergistic sites. Herein, we observed evidence for interfacial geometric interactions (IGIs) at Pt–C interfaces through a combination of atomic-scale structural analysis, in situ X-ray absorption fine structure, and electrochemical measurements for Pt/C model systems. The IGI has a long-range attribute and affects Pt surface atoms not only at interfacial perimeters but also adjacent to interfaces. The affected Pt surface atoms are proposed to contribute enhanced activity and stability for the oxygen reduction reaction through retarding the formation of strongly adsorbed oxygenated intermediates. Our work provides some necessary information for a better understanding of support effects and catalytically active surface sites.

Developing highly efficient multifunctional electrocatalysts is crucial for future sustainable energy pursuits, but remains a great challenge. Herein, a facile synthetic strategy is used to confine atomically thin Pd-PdO nanodomains to amorphous Ru metallene oxide (RuO2 ). The as-synthesized electrocatalyst (Pd2 RuOx-0.5 h) exhibits excellent catalytic activity toward the pH-universal hydrogen evolution reaction (η10 = 14 mV in 1 m KOH, η10 = 12 mV in 0.5 m H2 SO4 , and η10 = 22 mV in 1 m PBS), alkaline oxygen evolution reaction (η10 = 225 mV), and overall water splitting (E10 = 1.49 V) with high mass activity and operational stability. Further reduction endows the material (Pd2 RuOx-2 h) with a promising alkaline oxygen reduction activity, evidenced by high halfway potential, four-electron selectivity, and excellent poison tolerance. The enhanced catalytic activity is attributed to the rational integration of favorable nanostructures, including 1) the atomically thin nanosheet morphology, 2) the coexisting amorphous and defective crystalline phases, and 3) the multi-component heterostructural features. These structural factors effectively regulate the material's electronic configuration and the adsorption of intermediates at the active sites for favorable reaction energetics. Ministry of Education (MOE) This work was financially supported by the AcRF Tier 1 (grant RG105/19) provided by the Ministry of Education in Singapore and the Foundation of State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering (grant no. 2022-K31).

Water management is important for stable operation of PEFCs (Polymer Electrolyte Fuel Cells), since the proton conductivity depends on water content and excessive water hinders electrochemical reactions. As the durability of PEFC has become a major issue, the correlative behavior between liquid water and cerium oxides (radical scavengers) is drawing much attention. Till now, the water content and its inhomogeneous distributions have been reported by neutron radiography and X-ray computed tomography (CT). In this paper, we present a high-energy Compton scattering imaging (CSI) technique for non-destructive observation of liquid water in PEFC. The advantage of high-energy CSI over X-ray CT is that the CSI technique has direct access to a two-dimensional cross section inside a PEFC without its rotation. The radiation damage on polymer electrolyte membranes is negligibly small since the photoelectric absorption is substantially reduced at such high-energy X-rays. Although high-energy X-ray CT is not sensitive to light-element materials, X-ray Compton scattering has its sensitivity to light elements. Figure 1 shows the cross-sectional images of GDL (Gas Diffusion Layer) materials and liquid water [1]. The GDL materials are made of porous carbon fibers and carbon composites with Teflon treatment, TGP-H-300 (TORAY Industries, Inc., Tokyo, Japan). The area of the cross sections is 2mm x 2mm, and its thickness is 10μm. The spatial resolution is 75 μm. Figure 1(a) shows the image of dry GDL materials, displaying the distribution of carbon fibers and carbon composite, and Figure 1(b) does the difference image between dry and wet, representing the liquid water distribution. Negative contributions are observed in the carbon fiber and carbon composite region, which indicates possible interactions between the GDL materials and liquid water. In this presentation, applications to a model cell under operation are also presented, together with correlation mappings of liquid water and cerium. The capability of CSI for vehicles’ PEFCs (TOYOTA MIRAI) is also discussed. This work was performed under the NEDO FC-Platform project. [1] N. Tsuji et al., Appl. Sci. 11, 3851 (2021) Figure Caption: Fig.1: Cross-sectional images of GDL materials and liquid water. Figure 1

Polymer electrolyte fuel cells (PEFCs) consist of a gas diffusion layer (GDL) and an electrode on each side, and a polymer electrolyte membrane (MEA) between the electrodes. The main components of the MEA are catalysts, electrolyte membranes and electrodes. In this study, the local atomic structures of catalytic nanoparticles in MEA were investigated by high-energy X-ray diffraction measurement and reverse Monte Carlo (RMC) modeling. The purpose of this study is to show guidelines for improving the performance of the PEFCs that contribute to industry by clarifying the differences in each catalyst structure and linking them with catalyst performance such as catalytic activity and catalyst durability. In this conference, we report the structural work on the platinum nanoparticles-supported carbon catalyst TEC10V30E (manufactured by TANAKA KIKINZOKU KOGYO K.K.). Although this sample is a commercial product, it is important to investigate its structure because it can be used as a standard sample for evaluating various catalyst samples in the future. RMC modeling based on the structure factor S(Q) obtained from high-energy X-ray diffraction measurement is suitable to determine the 3-dimensional (3D) atomic structures of nanoparticles. High-energy X-ray diffraction measurements were performed using a two-axis diffractometer at the beamline BL04B2 in SPring-8; the energy was used 61.4 keV corresponding to 0.202 Å in wavelength. RMC simulations were performed to obtain structure information from RMC-generated 3D configuration models using RMC_POT software in the case of non-periodic boundary conditions for experimental structure factor data. Figure 1 shows the experimental structure factor of the Pt nanoparticles in TEC10V30E and the RMC-simulated structure factor. For the Pt nanoparticle studied here, the initial configuration of the RMC simulations is a spherical shape with 3.8 nm in diameter based on the fcc bulk crystal structure. The agreement between the experiment and the RMC-simulated S(Q) is satisfactory. The 3D structure model of the Pt nanoparticle obtained by RMC simulations is shown in Fig. 1. It was found that the deviation from the lattice position was larger on the surface than on the inside in the obtained structure model. This research approach is expected to accelerate the creation of new catalysts for fuel cells by providing local atomic-scale structural information. It is also important to create the database of atomic arrangement structure data that is the basis of material design and material research. In the meeting, data recorded from actual catalyst samples will also be presented, including those from the MIRAI fuel cell (manufactured by Toyota Motor Corp.). This work was performed under the NEDO FC-Platform project. Figure 1

Jellyfish (JF) mucin (precisely, a mucin-type glycoprotein named qniumucin: Q-mucin) first discovered in JF is mainly composed of highly O-glycosylated domains, and its unique structure suggests its wide applications as a smart material. In this study, the standard protocol used to date was thoroughly reinvestigated because the processing of raw JF was rather difficult and continuous production from frozen sources was also indispensable. Finally, we concluded that Q-mucin is involved not in mucus but in the mesoglea, i.e., the extracellular matrix (ECM), as a part of a very large polymer complex. We added a treatment procedure with a chelate reagent (e.g. EDTA) to inactivate endogenous proteases that induce the spontaneous decomposition of the collagens in ECM. The amino acid composition (AAC) of each precipitate formed upon EtOH addition indicated that Q-mucin dissociates from the biopolymer complex as a constituent highly soluble in deionized water. Since the remaining portion of ECM still seemed to contain a large amount of the precursor of Q-mucin even after the extraction with water is completed, the yield of Q-mucin is expected to increase markedly if an innovative method to decompose EtOH precipitates is developed. The existence of Q-mucin in ECM seems to be described in parallel with that of proteoglycans (PG) in mammalian cartilage because they resemble each other.

Catalytic benzene C-H activation toward selective phenol synthesis with O2 remains a stimulating challenge to be tackled. Phenol is currently produced industrially by the three-steps cumene process in liquid phase, which is energy-intensive and not environmentally friendly. Hence, there is a strong demand for an alternative gas-phase single-path reaction process. This account documents the pivotal confined single metal ion site platform with a sufficiently large coordination sphere in β zeolite pores, which promotes the unprecedented catalysis for the selective benzene hydroxylation with O2 under coexisting NH3 by the new inter-ligand concerted mechanism. Among alkali and alkaline-earth metal ions and transition and precious metal ions, single Cs+ and Rb+ sites with ion diameters >0.300 nm in the β pores exhibited good performances for the direct phenol synthesis in a gas-phase single-path reaction process. The single Cs+ and Rb+ sites that possess neither significant Lewis acidic-basic property nor redox property, cannot activate benzene, O2 , and NH3 , respectively, whereas when they coadsorbed together, the reaction of the inter-coadsorbates on the single alkali-metal ion site proceeds concertedly (the inter-ligand concerted mechanism), bringing about the benzene C-H activation toward phenol synthesis. The NH3 -driven benzene C-H activation with O2 was compared to the switchover of the reaction pathways from the deep oxidation to selective oxidation of benzene by coexisting NH3 on Pt6 metallic cluster/β and Ni4 O4 oxide cluster/β. The NH3 -driven selective oxidation mechanism observed with the Cs+ /β and Rb+ /β differs from the traditional redox catalysis (Mars-van Krevelen) mechanism, simple Langmuir-Hinshelwood mechanism, and acid-base catalysis mechanism involving clearly defined interaction modes. The present catalysis concept opens a new way for catalytic selective oxidation processes involving direct phenol synthesis.

A method enabling the accurate and precise correlation between structures and properties is critical to the development of efficient electrocatalysts. To this end, we developed an integrated single-electrode method (ISM) that intimately couples electrochemical rotating disk electrodes, in situ/operando X-ray absorption fine structures, and aberration-corrected transmission electron microscopy on identical electrodes. This all-in-one method allows for the one-to-one, in situ/operando, and atomic-scale correlation between structures of electrocatalysts with their electrochemical reactivities, distinct from common methods that adopt multisamples separately for electrochemical and physical characterizations. Because the atomic step is one of the most fundamentally structural elements in electrocatalysts, we demonstrated the feasibility of ISM by exploring the roles of atomic steps in the reactivity of electrocatalysts. In situ and atomic-scale evidence shows that low-coordinated atomic steps not only generate reactive species at low potentials and strengthen surface contraction but also act as templates to disturb interfacial water networks and thus affect the reactivity of electrocatalysts. This template role interprets the long-standing puzzle regarding why high-index facets are active for the oxygen reduction reaction in acidic media. The ISM as a fundamentally new method for workflows should aid the study of many other electrocatalysts regarding their nature of active sites and operative mechanisms.

Highlights Secondary-atom-doped strategy was proposed to synthesize single-atom electrocatalyst.The increase in both the density of active sites and their intrinsic activity was achieved simultaneously.The resultant single-atom catalyst shows outstanding ORR activity in acidic media. Electronic supplementary material The online version of this article (10.1007/s40820-020-00502-5) contains supplementary material, which is available to authorized users., Single-atom catalysts (SACs) with nitrogen-coordinated nonprecious metal sites have exhibited inimitable advantages in electrocatalysis. However, a large room for improving their activity and durability remains. Herein, we construct atomically dispersed Fe sites in N-doped carbon supports by secondary-atom-doped strategy. Upon the secondary doping, the density and coordination environment of active sites can be efficiently tuned, enabling the simultaneous improvement in the number and reactivity of the active site. Besides, structure optimizations in terms of the enlarged surface area and improved hydrophilicity can be achieved simultaneously. Due to the beneficial microstructure and abundant highly active FeN5 moieties resulting from the secondary doping, the resultant catalyst exhibits an admirable half-wave potential of 0.81 V versus 0.83 V for Pt/C and much better stability than Pt/C in acidic media. This work would offer a general strategy for the design and preparation of highly active SACs for electrochemical energy devices. Electronic supplementary material The online version of this article (10.1007/s40820-020-00502-5) contains supplementary material, which is available to authorized users.

This study presents surface nitriding of 4H-SiC by the irradiation of the fourth harmonics of Nd:YAG laser pulses in liquid nitrogen. A nitride layer with a depth of 1 mu m is formed on the irradiated area. The irradiated area has a bumpy morphology. On the other hand, we also find a nitride layer with a smooth surface morphology in the outside of the irradiated area. The concentration of nitrogen is dependent on the laser fluence, and is 1-5%. The diffusion coefficient of nitrogen, which is deduced from the depth profile of the nitrogen number density, is much greater than the diffusion coefficient in solid SiC, suggesting the transport of nitrogen in melted SiC. Considering the fact that SiC does not have a melted state at the atmospheric pressure, it is revealed by the present work that the melted SiC is realized transiently with the help of the high pressure driven by the laser irradiation.

The synchronizing measurements of both cyclic voltammograms (CVs) and real-time quick XAFSs (QXAFSs) for Pt/C cathode electrocatalysts in a membrane electrode assembly (MEA) of polymer electrolyte fuel cells (PEFCs) treated by anode-gas exchange (AGEX) and cathode-gas exchange (CGEX) cycles (startup/shutdown conditions of FC vehicles) were performed for the first time to understand the opposite effects of the AGEX and CGEX treatments on the Pt/C performance and durability and also the contradiction between the electrochemical active surface area (ECSA) decrease and the performance increase by CGEX treatment. While the AGEX treatment decreased both the ECSA and performance of MEA Pt/C due to carbon corrosion, it was found that the CGEX treatment decreased the ECSA but increased the Pt/C performance significantly due to high-index (331) facet formation (high-resolution STEM) and hence the suppression of strongly bound Pt-oxide formation at cathode Pt nanoparticle surfaces. Transient QXAFS time-profile analysis for the MEA Pt/C also revealed a direct relationship between the electrochemical performance or durability and transient kinetics of the Pt/C cathode.

Single-atom electrocatalysts (SAEs) can realize the target of low-cost by maximum atomic efficiency. However, they usually suffer performance decay due to high energy states, especially in a harsh acidic water splitting environment. Here, we conceive and realize a double protecting strategy that ensures robust acidic water splitting on Ir SAEs by dispersing Ir atoms in/onto Fe nanoparticles and embedding IrFe nanoparticles into nitrogen-doped carbon nanotubes (Ir-SA@Fe@NCNT). When Ir-SA@Fe@NCNT acts as a bifunctional electrocatalyst at ultralow Ir loading of 1.14 μg cm

We have shown that measuring the surface tension is a useful scheme to examine the plasma–liquid interface in real-time. The surface tension was measured using a method based on the dispersion relation of an acoustic capillary wave excited on the water surface. The surface tension gradually increased with time, when the water surface was irradiated with the outside region of the spatial afterglow of an atmospheric-pressure plasma. The Marangoni effect associated with the localized increase in the surface tension was observed during the plasma irradiation. The surface tension decreased after the termination of the discharge. A correlation was found between the transient decrease in the surface tension and the variation of the OH radical density in the gas phase. No increase in the surface tension was observed in the solution containing a trapping agent for liquid-phase OH radicals. These experimental results suggest that OH radicals act to increase the surface tension. However, the behavior of the surface tension cannot be explained perfectly by considering only the action of OH radicals.

The well-known cumene process via an explosive cumene hydroperoxide intermediate in liquid phase currently employed for phenol production is energy-intensive and not environmentally friendly. Therefore, there is a demand for an alternative single-step gas-phase catalysis process. According to the conventional catalysis concept, selective oxidation reactions are promoted by redox catalysts and not by acid–base catalysts. In general, alkali and alkaline earth metal ions cannot activate each of benzene, O2, and N2O when they adsorb separately. However, we observed an unprecedented catalysis of single alkali and alkaline earth metal ion sites incorporated into zeolite pores for the selective oxidation of benzene to phenol with N2O and O2 + NH3, thereby providing a single-site catalytic platform with high selectivity. Among alkali and alkaline earth metal ions, single Cs+ and Rb+ sites with ion diameters of >300 pm in the pores of β-zeolites exhibited remarkable selectivity for benzene C–H activation to phenol catalysis in a concerted reaction pathway.

It remains a big challenge to remarkably improve both oxygen reduction reaction (ORR) activity and long-term durability of Pt-M bimetal electrocatalysts simultaneously in the harsh cathode environment toward widespread commercialization of polymer electrolyte fuel cells (PEFC). In this account we found double-promotional effects of carbon micro coil (CMC) support on ORR performance and durability of octahedral Pt3 Ni nanoparticles (Oh Pt3 Ni/CMC). The Oh Pt3 Ni/CMC displayed remarkable improvements of mass activity (MA; 13.6 and 34.1 times) and surface specific activity (SA; 31.3 and 37.0 times) compared to those of benchmark Pt/C (TEC10E20E) and Pt/C (TEC10E50E-HT), respectively. Notably, the Oh Pt3 Ni/CMC revealed a negligible MA loss after 50,000 triangular-wave 1.0-1.5 VRHE (startup/shutdown) load cycles, contrasted to MA losses of 40 % (TEC10E20E) and 21.5 % (TEC10E50E-HT) by only 10,000 load cycles. It was also found that the SA increased exponentially with the decrease in the CO stripping peak potential in a series of Pt-M/carbon (M: Ni and Co), which predicts a maximum SA at the curve asymptote. Key factors for simultaneous improvements of performance and durability of core-shell Pt3 Ni/carbon electrocatalysts toward superior PEFC is also discussed.

In order to obtain a suitable design policy for the development of a next-generation polymer electrolyte fuel cell, we performed a visualization analysis of Pt and Co species following aging and degradation processes in membrane-electrode assembly (MEA), using a same-view. Nano-X-ray absorption fine structure (XAFS)/Scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS) technique that we developed to elucidate durability factors and degradation mechanisms of a MEA Pt

It is hard to directly visualize spectroscopic and atomic-nanoscopic information on the degraded Pt/C cathode layer inside polymer electrolyte fuel cell (PEFC). However, it is mandatory to understand the preferential area, sequence, and relationship of the degradations of Pt nanoparticles and carbon support in the Pt/C cathode layer by directly observing the Pt/C cathode catalyst for the development of next-generation PEFC cathode catalysts. Here, the spectroscopic, chemical, and morphological visualization of the degradation of Pt/C cathode electrocatalysts in PEFC was performed successfully by a same-view combination technique of nano-X-ray absorption fine structure (XAFS) and transmission electron microscopy (TEM)/scanning TEM-energy-dispersive spectrometry (EDS) under a humid N2 atmosphere. The same-view nano-XAFS and TEM/STEM-EDS imaging of the Pt/C cathode of PEFC after triangular-wave 1.0-1.5 VRHE (startup/shutdown) accelerated durability test (tri-ADT) cycles elucidated the site-selective area, sequence, and relationship of the degradations of Pt nanoparticles and carbon support in the Pt/C cathode layer. The 10 tri-ADT cycles caused a carbon corrosion to reduce the carbon size preferentially in the boundary regions of the cathode layer with both electrolyte and holes/cracks, accompanied with detachment of Pt nanoparticles from the degraded carbon. After the decrease in the carbon size to less than 8 nm by the 20 tri-ADT cycles, Pt nanoparticles around the extremely corroded carbon areas were found to transform and dissolve into oxidized Pt2+-O4 species.

This account article treats with the key structural transformations and kinetics of Pt nanoparticles in Pt/C cathode catalysts under transient voltage operations (0.4 VRHE→1.4 VRHE→0.4 VRHE) by simultaneous operando time-resolved QXAFS–XRD measurements, summarizing and analyzing our previous kinetic data in more detail and discussing on the key reaction steps and rate constants for the performance and durability of polymer electrolyte fuel cells (PEFC). The time-resolved QXAFS–XRD measurements were conducted at each acquisition time of 20 ms, while measuring the current/charge of the PEFC. The rate constants for the transient responses of Pt valence, CN(Pt–O) (CN: coordination number), CN(Pt–Pt), and Pt metallic-phase core size under the transient voltage operations were determined by the combined time-resolved QXAFS‒XRD technique. The relationship of the structural kinetics with the performance and durability of the PEFC Pt/C was also documented as key issues for the development of next-generation PEFCs. The present account emphasizes the time-resolved QXAFS and XRD techniques to be a powerful technique to analyze directly the structural and electronic change of metal nanoparticles inside PEFC under the operating conditions.

Transient-response kinetics of the transformations (six elementary steps) of the Pt valence, coordination number of Pt–Pt bonds, and coordination number of Pt–O bonds of a Pt/C cathode catalyst in a polymer electrolyte fuel cell (PEFC) under cyclic voltage operations (0.4 → 1.4 → 0.4 VRHE) during anode–gas exchange (AGEX) treatments (start-up/shut-down) has been studied by in situ time-resolved quick X-ray absorption fine structure (QXAFS, 100 ms/spectrum). The transient-response analysis identified the existence and fractions of three different kinds (active, less active, and inactive) of Pt nanoparticles in the Pt/C cathode. The active Pt nanoparticles degraded to less active and inactive Pt nanoparticles by the AGEX cycles. The degradation probability and mechanism were clarified by the transient-response kinetics. The electrochemical surface area (ECSA) and mass activity (MA) of the Pt/C cathode catalyst also decreased with increasing AGEX cycles. It was found that the change in the sum of the fractio...

Simultaneous improvements in oxygen reduction reaction (ORR) activity and long-term durability of Pt-based cathode catalysts are indispensable for the development of next-generation polymer electrolyte fuel cells but are still a major dilemma. We present a robust octahedral core–shell PtNix/C electrocatalyst with high ORR performance (mass activity and surface specific activity 6.8–16.9 and 20.3–24.0 times larger than those of Pt/C, respectively) and durability (negligible loss after 10000 accelerated durability test (ADT) cycles). The key factors of the robust octahedral nanostructure (core–shell Pt73Ni27/C) responsible for the remarkable activity and durability were found to be three continuous Pt skin layers with 2.0–3.6% compressive strain, concave facet arrangements (concave defects and high coordination), a symmetric Pt/Ni distribution, and a Pt67Ni33 intermetallic core, as found by STEM-EDS, in situ XAFS, XPS, etc. The robust core–shell Pt73Ni27/C was produced by the partial release of the stress, Pt/Ni rearrangement, and dimension reduction of an as-synthesized octahedral Pt50Ni50/C with 3.6–6.7% compressive Pt skin layers by Ni leaching during the activation process. The present results on the tailored synthesis of the PtNix structure and composition and the better control of the robust catalytic architecture renew the current knowledge and viewpoint for instability of octahedral PtNix/C samples to provide a new insight into the development of next-generation PEFC cathode catalysts.

We have succeeded in simultaneous operando time-resolved quick X-ray absorption fine structure (QXAFS)–X-ray diffraction (XRD) measurements at each acquisition time of 20 ms for a Pt/C cathode catalyst in a polymer electrolyte fuel cell (PEFC), while measuring the current/charge of the PEFC during the transient voltage cyclic processes (0.4 VRHE → 1.4 VRHE → 0.4 VRHE) under H2(anode)–N2(cathode). The rate constants for Pt–O bond formation/dissociation, Pt charging/discharging, Pt–Pt bond dissociation/reformation, and decrease/increase of Pt metallic-phase core size under the transient potential operations were determined by the combined time-resolved QXAFS–XRD technique. The present study provides a new insight into the transient-response reaction mechanism and structural transformation in the Pt surface layer and bulk, which are relevant to the origin of PEFC activity and durability as key issues for the development of next-generation PEFCs.

Catalytic benzene C-H activation toward selective phenol synthesis with O

This account article treats with spatially non-uniform degradation events of Pt/C cathode catalysts in polymer electrolyte fuel cells involving the formation and dissolution of positively charged Pt ions and detachment of metallic Pt nanoparticles/clusters, which were visualized by the same-view nano XAFS and STEM-EDS imaging technique under humid N2 atmosphere.

The dynamic structural and electronic transformations of Pt/C, Pd@Pt(1 ML)/C, Pd@Pt(2 ML)/C cathode catalysts in polymer electrolyte fuel cells (PEFCs) during the potential-step operating processes between 0.4 and 1.4 VRHE (potential vs RHE) were characterized by in-situ (operando) time-resolved Pt LIII-edge quick-XAFS at 100 ms time-resolution. Potential-dependent surface structures and oxidation states of Pt, Pd@Pt(1 ML) and Pd@Pt(2 ML) nanoparticles on carbon at 0.4 and 1.4 VRHE were also analyzed by in-situ Pt LIII-edge and Pd K-edge quick-XAFS. The Pt, Pd@Pt(1 ML) and Pd@Pt(2 ML) nanoparticle surfaces were restructured and disordered at 1.4 VRHE, which were induced by strong Pt-O bonds as well as alloying effects. The rate constants for the changes of Pt valence, CN(Pt-Pt), CN(Pt-Pd) and CN(Pt-O) (CN: coordination number) in the potential-step operating processes were also determined and discussed in relation to the origin of oxygen reduction reaction (ORR) activities of the Pt/C, Pd@Pt(1 ML)/C and Pd@Pt(2 ML)/C cathode catalysts.

It remains a big challenge to remarkably improve both oxygen reduction reaction (ORR) activity and long-term durability of Pt-M bimetal electrocatalysts simultaneously in the harsh cathode environment toward widespread commercialization of polymer electrolyte fuel cells (PEFC). In this account we found double-promotional effects of carbon micro coil (CMC) support on ORR performance and durability of octahedral Pt

Extranodal extension (ENE) of nodal metastasis is defined as the extension of metastatic cells through the nodal capsule into the perinodal tissue. This morphological parameter, recently proposed as an important prognostic factor in different types of malignancy, has not been included in the TNM staging system for non-small cell lung cancer (NSCLC). In this systematic review with meta-analysis, we weighted the prognostic role of ENE in patients with lymph node-positive NSCLC. Two independent authors searched SCOPUS and PubMed through 28 February 2017. Prospective and retrospective studies on NSCLC, comparing patients with presence of ENE (ENE+) ENE+) vs. only intranodal extension (ENE–) and including data regarding prognosis, were considered as eligible. Data were summarized using risk ratios (RR) for the number of deaths/recurrences, and hazard ratios (HR) with 95% confidence intervals (CI) for time-dependent risk related to ENE+, adjusted for potential confounders. We identified 13 studies, including 1709 patients (573 ENE+ and 1136 ENE–) with a median follow-up of 60months. ENE was associated with a significantly increased risk of mortality of all causes (RR = 1.39, 95% CI: 1.18–1.65, P < 0.0001, I2= 70%; HR = 1.30, 95% CI: 1.01–1.67, P = 0.04, I2= 0%) and of disease recurrence (RR = 1.32, 95% CI: 1.04–1.68, P = 0.02, I2= 42%; HR = 1.93, 95% CI: 1.53–2.44, P < 0.0001, I2= 0%). We conclude that in NSCLC, requirements for assessment of ENE should be included in gross sampling and ENE status should be included in the pathology report. Inclusion of ENE status in oncology staging systems will allow further assessment of its role as prognostic parameter. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

Background and Objectives Lymph node involvement is common in thyroid cancer, but the system of staging does not consider the histological features of lymph node metastases. We conducted a meta-analysis to investigate the prognostic role of extranodal extension (ENE) in thyroid cancer patients. Methods We ran PubMed and SCOPUS searches without language restrictions. Prospective studies reporting data on overall mortality, cancer-specific mortality, or disease recurrence including thyroid cancer patients, in which cases with ENE (ENE+) were compared with those with only intranodal disease (ENE−) were eligible. Data were summarized using risk ratios (RR) for number of deaths/recurrences, and hazard ratios (HR) for time-dependent risks related to ENE+ status, adjusted for potential confounders. Results Of 414 hits, 23 studies were eligible and included. Compared to ENE−, patients who were ENE+ had significantly higher rates of all-cause mortality (studies = 8; RR = 3.25; 95%CI: 1.35–2.64, I2 = 83%) and recurrence (studies = 17; RR = 2.64, 95%CI: 1.93–3.60, I2 = 73%). Using HRs adjusted for potential confounders, ENE+ status carried a significantly higher risk of all-cause and cancer-specific mortality and disease recurrence. Conclusion It becomes mandatory to consider ENE in the histopathological examination of surgical samples in thyroid cancer patients, and this factor should be included in future oncological staging systems. J. Surg. Oncol. © 2015 Wiley Periodicals, Inc.

We have achieved significant improvements for the oxygen reduction reaction activity and durability with new SnO2-nanoislands/Pt3Co/C catalysts in 0.1 M HClO4, which were regulated by a strategic fabrication using a new selective electrochemical Sn deposition method. The nano-SnO2/Pt3Co/C catalysts with Pt/Sn = 4/1, 9/1, 11/1, and 15/1 were characterized by STEM-EDS, XRD, XRF, XPS, in situ XAFS, and electrochemical measurements to have a Pt3Co core/Pt skeleton-skin structure decorated with SnO2 nanoislands at the compressive Pt surface with the defects and dislocations. The high performances of nano-SnO2/Pt3Co/C originate from efficient electronic modification of the Pt skin surface (site 1) by both the Co of the Pt3Co core and surface nano-SnO2 and more from the unique property of the periphery sites of the SnO2 nanoislands at the compressive Pt skeleton-skin surface (more active site 2), which were much more active than expected from the d-band center values. The white line peak intensity of the nano-SnO2/Pt3Co/C revealed no hysteresis in the potential up-down operations between 0.4 and 1.0 V versus RHE, unlike the cases of Pt/C and Pt3Co/C, resulting in the high ORR performance. Here we report development of a new class of cathode catalysts with two different active sites for next-generation polymer electrolyte fuel cells.

Repeated anode gas exchange (AGEX) cycles and cathode gas exchange (CGEX) cycles were applied to MEAs with Pt3Co/C cathode catalysts to investigate the degradation processes and to compare with the case of Pt/C. The structural and electronic changes of the catalysts during the feed gas-exchange cycles were examined at the top position area of the MEAs by in-situ XAFS and at the top and bottom positions by STEM-EDS. The ORR performance decreased steadily by the AGEX cycles though STEM revealed neither large cracks nor voids nor detached particles in the top position area of the MEA by the AGEX cycles where the electrochemical surface area (ECSA) remained unchanged. On the other hand, neither ORR performance nor ECSA decreased by the CGEX cycles though the particle size only in the bottom position area increased a little after the CGEX treatment. In-situ time-resolved XAFS spectra at Pt LIII-edge showed a decrease of the XANES white line peak height in case of the AGEX, which is not due to particle growth.

We have made the first success in the same-view imagings of 2D nano-XAFS and TEM/STEM-EDS under a humid N2 atmosphere for Pt/C cathode catalyst layers in membrane electrode assemblies (MEAs) of polymer electrolyte fuel cells (PEFCs) with Nafion membrane to examine the degradation of Pt/C cathodes by anode gas exchange cycles (start-up/shut-down simulations of PEFC vehicles). The same-view imaging under the humid N2 atmosphere provided unprecedented spatial information on the distribution of Pt nanoparticles and oxidation states in the Pt/C cathode catalyst layer as well as Nafion ionomer-filled nanoholes of carbon support in the wet MEA, which evidence the origin of the formation of Pt oxidation species and isolated Pt nanoparticles in the nanohole areas of the cathode layer with different Pt/ionomer ratios, relevant to the degradation of PEFC catalysts.

Repeated, quick anode gas-exchange (AGEX) or cathode gas-exchange (CGEX) cycles were applied to polymer electrolyte fuel cell (PEFC) membrane electrode assemblies (MEAs) with Pt/C cathode catalysts to simulate start-up/shut-down conditions and to examine a possible countermeasure for their effects on MEA cathode catalyst degradation. The peak height of the white line during in situ time-resolved X-ray absorption near-edge structure (XANES) spectra at the Pt LIII-edge decreased with an increasing number of AGEX cycles and only in the top region of the MEA cathode layer (close to the gas inlet of the fuel cell), not in the whole MEA area. End-of-life analysis after AGEX by using SEM and TEM revealed isolated Pt nanoparticles in micro-cracks and voids produced in the top region of the MEA cathode layer. The nanoparticle sizes remained almost unchanged for top, middle, and bottom regions of the MEA cathode layer. In the case of CGEX, a small increase in the Pt nanoparticle sizes in the top and bottom positions of the MEA cathode layer was observed. These findings support the role of carbon corrosion, leaving isolated, electrochemically inactive Pt nanoparticles as a consequence of the harsh reaction conditions caused by the reverse current decay mechanism during the start-up/shut-down phase, as in the case of AGEX cycles, to be the main cause for the cathode catalyst deterioration close to the anode gas inlet. On the other hand, the hydrogen gas feed to both the anode and cathode during start-up and shut-down processes seems to effectively suppress carbon corrosion and prevents a decrease in the performance.

There is limited information on the mechanism for platinum oxidation and dissolution in Pt/C cathode catalyst layers of polymer electrolyte fuel cells (PEFCs) under the operating conditions though these issues should be uncovered for the development of next-generation PEFCs. Pt species in Pt/C cathode catalyst layers are mapped by a XAFS (X-ray absorption fine structure) method and by a quick-XAFS(QXAFS) method. Information on the site-preferential oxidation and leaching of Pt cathode nanoparticles around the cathode boundary and the micro-crack in degraded PEFCs is provided, which is relevant to the origin and mechanism of PEFC degradation.

In this paper we present a complex linear prediction analysis method for estimating the formant frequencies of noisy speech. The proposed method effectively utilizes the signal (being the analytic signal) which is ignored in the conventional complex linear prediction analysis to achieve noise reduction. Also, the covariance and forward-backward linear prediction (FBLP) methods are compared, and the FBLP method is deployed for predictive coefficients estimation in the proposed method. Experimental results show that the proposed method yields better performance of formant estimation when compared to some conventional methods in white noise. 

The extranodal extension (ENE) of nodal metastasis is the extension of neoplastic cells through the nodal capsule into the perinodal adipose tissue. This histological feature has recently been indicated as an important prognostic factor in different types of malignancies; in this manuscript, we aim at defining its role in the prognosis of oesophageal cancer with the tool of meta-analysis. Two independent authors searched SCOPUS and PubMed until 31 August 2015 without language restrictions. The studies with available data about prognostic parameters in subjects with oesophageal cancer, comparing patients with the presence of ENE (ENE+) versus only intranodal extension (ENE-), were considered as eligible. Data were summarised using risk ratios (RRs) for number of deaths/recurrences and HRs together with 95% CIs for time-dependent risk related to ENE+, adjusted for potential confounders. Fourteen studies were selected; they followed-up 1437 patients with oesophageal cancer for a median follow-up of 39.4months. The presence of ENE was associated with a significantly increased risk of all-cause mortality (RR=1.33; 95% CI 1.18 to 1.50, p

The spring-type near isogenic line (NIL) of the winter-type barley (Hordeum vulgare ssp. vulgare) var. Hayakiso 2 (HK2) was developed by introducing VERNALIZATION-H1 (Vrn-H1) for spring growth habit from the spring-type var. Indo Omugi. Contrary to expectations, the spring-type NIL flowered later than winter-type HK2. This phenotypic difference was controlled by a single gene, which cosegregated only with phytochrome C (HvPhyC) among three candidates around the Vrn-H1 region (Vrn-H1, HvPhyC, and CASEIN KINASE IIα), indicating that HvPhyC was the most likely candidate gene. Compared with the late-flowering allele HvPhyC-l from the NIL, the early-flowering allele HvPhyC-e from HK2 had a single nucleotide polymorphism T1139C in exon 1, which caused a nonsynonymous amino acid substitution of phenylalanine at position 380 by serine in the functionally essential GAF (3′, 5′-cyclic-GMP phosphodiesterase, adenylate cyclase, formate hydrogen lyase activator protein) domain. Functional assay using a rice (Oryza sativa) phyA phyC double mutant line showed that both of the HvPhyC alleles are functional, but HvPhyC-e may have a hyperfunction. Expression analysis using NILs carrying HvPhyC-e and HvPhyC-l (NIL [HvPhyC-e] and NIL [HvPhyC-l], respectively) showed that HvPhyC-e up-regulated only the flowering promoter FLOWERING LOCUS T1 by bypassing the circadian clock genes and flowering integrator CONSTANS1 under a long photoperiod. Consistent with the up-regulation, NIL (HvPhyC-e) flowered earlier than NIL (HvPhyC-l) under long photoperiods. These results implied that HvPhyC is a key factor to control long-day flowering directly.