Metallic bonds and thermal vibration in brass.

Nature of the metallic bond and thermal vibration in brass alloy is investigated from the local structural and thermodynamical points of view by the temperature-dependent Cu and Zn K-edge extended X-ray absorption fine structure spectroscopy and the path-integral effective classical potential theoretical simulation. It is unexpectedly found that the thermal vibrational amplitude around Zn is a little but meaningfully smaller than that around Cu, although it is usually believed that Zn is a much softer metal than Cu in terms of various thermodynamical physical quantities of elemental metals. Moreover, it is found that the nearest neighbor distance around Zn is almost equivalent to that around Cu (only ∼0.01 Šdifference), although the metallic radius of Zn commonly used is considerably larger than that of Cu (∼0.06-0.09 Šdifference). These peculiar findings can be interpreted as a result of confinement of Zn atoms in a smaller space than usual and a significantly larger repulsive potential of Zn than Cu.

Clinical efficacy of osimertinib in EGFR-mutant non-small cell lung cancer with distant metastasis.

BACKGROUND: Osimertinib-the third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI)-has been widely used as a first-line treatment for patients with metastatic EGFR-mutant non-small cell lung cancer (NSCLC). Osimertinib demonstrated central nervous system activity in patients with brain metastasis; however, its efficacy against other distant metastatic organs, including bone and liver, remains unclear. Therefore, we retrospectively analyzed the clinical efficacy of osimertinib in these patients in comparison to other EGFR-TKIs. METHODS: Clinical data of patients with advanced NSCLC receiving gefitinib/erlotinib (n = 183), afatinib (n = 55), or osimertinib (n = 150) at five medical institutions were retrospectively assessed for progression-free survival (PFS), overall survival (OS), and best overall response rate (ORR). RESULTS: In univariate and multivariate analyses, most distant metastases, including the brain and bone, were unrelated to the therapeutic efficacy of osimertinib, although liver metastasis and L858R mutation were independently associated with shorter PFS. PFS and OS in patients with liver metastases were significantly shorter than those in patients without liver metastases (PFS: 7.4 vs. 19.7 months, OS: 12.1 months vs. not reached, respectively). Osimertinib provided significantly longer PFS in patients with brain or bone metastasis and exon 19 deletion than the other EGFR-TKIs. The PFS of patients with liver metastases was not significantly different among the three EGFR-TKI groups. Furthermore, the ORR of osimertinib in patients with liver metastases was significantly attenuated, and the effectiveness was similar to 1st- or 2nd -generation EGFR-TKIs. CONCLUSION: Osimertinib provided better clinical benefits than 1st- and 2nd-generation EGFR-TKIs for patients with EGFR-mutant NSCLC, particularly those with brain or bone metastases and exon 19 deletion; however, its efficacy against liver metastasis was remarkably attenuated. New therapeutic developments for patients with EGFR-mutant NSCLC with liver metastases are needed.

Sulfur poisoning of Pt and PtCo anode and cathode catalysts in polymer electrolyte fuel cells studied by operando near ambient pressure hard X-ray photoelectron spectroscopy.

We have investigated the S adsorption behaviours on Pt (average particle diameter of ∼2.6 nm) and Pt3Co (∼3.0 nm) anode and cathode electrode catalysts in polymer electrolyte fuel cells (PEFCs) under working conditions for the fresh state just after the aging process and also the degraded state after accelerated degradation tests (ADT), by studying near ambient pressure hard X-ray photoelectron spectroscopy (HAXPES). S 1s HAXPES of both the anode and cathode electrodes shows not only the principal S species from the sulfonic acid group (-SO3H) in the Nafion electrolyte but also other characteristic S species such as zero-valent S (S0) adsorbed on the carbon support and anionic S (S2-) adsorbed on the Pt electrode. The S2- species on Pt should be ascribed to S contamination poisoning the Pt catalyst electrode. The S2- species on the cathode can be oxidatively removed by applying a high cathode-anode bias voltage (≥0.8 V) to form SO32-, while at the anode the S2- species cannot be eliminated because of reductive environment in hydrogen gas. The important finding is the difference in S adsorption behaviours between the Pt/C and Pt3Co/C electrodes after ADT. After ADT, the Pt/C anode electrode exhibits much larger S2- adsorption than the Pt3Co/C anode electrode. This indicates that the Pt3Co/C anode is more desirable than the Pt/C one from the viewpoint of S poisoning. The reason for more tolerance of the Pt3Co/C anode catalyst against S poisoning after ADT can be ascribed to the more negative charge of the surface Pt atoms in the Pt3Co/C catalyst than those in the Pt/C one, thus yielding a weaker interaction between the surface Pt and the anionic S species as S2-, SO32-, and SO42-. A similar behaviour was observed also in the cathode catalyst. The present findings will nevertheless provide important information to design novel Pt-based PEFC electrodes with higher performance and longer durability.

A Prospective, Randomized, Open-Label Trial of Early versus Late Favipiravir Therapy in Hospitalized Patients with COVID-19.

Favipiravir is an oral broad-spectrum inhibitor of viral RNA-dependent RNA polymerase that is approved for treatment of influenza in Japan. We conducted a prospective, randomized, open-label, multicenter trial of favipiravir for the treatment of COVID-19 at 25 hospitals across Japan. Eligible patients were adolescents and adults admitted with COVID-19 who were asymptomatic or mildly ill and had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Patients were randomly assigned at a 1:1 ratio to early or late favipiravir therapy (in the latter case, the same regimen starting on day 6 instead of day 1). The primary endpoint was viral clearance by day 6. The secondary endpoint was change in viral load by day 6. Exploratory endpoints included time to defervescence and resolution of symptoms. Eighty-nine patients were enrolled, of whom 69 were virologically evaluable. Viral clearance occurred within 6 days in 66.7% and 56.1% of the early and late treatment groups (adjusted hazard ratio [aHR], 1.42; 95% confidence interval [95% CI], 0.76 to 2.62). Of 30 patients who had a fever (≥37.5°C) on day 1, times to defervescence were 2.1 days and 3.2 days in the early and late treatment groups (aHR, 1.88; 95% CI, 0.81 to 4.35). During therapy, 84.1% developed transient hyperuricemia. Favipiravir did not significantly improve viral clearance as measured by reverse transcription-PCR (RT-PCR) by day 6 but was associated with numerical reduction in time to defervescence. Neither disease progression nor death occurred in any of the patients in either treatment group during the 28-day participation. (This study has been registered with the Japan Registry of Clinical Trials under number jRCTs041190120.).

Photoinduced anisotropic distortion as the electron trapping site of tungsten trioxide by ultrafast W L1-edge X-ray absorption spectroscopy with full potential multiple scattering calculations.

Understanding the excited state of photocatalysts is significant to improve their activity for water splitting reaction. X-ray absorption fine structure (XAFS) spectroscopy in X-ray free electron lasers (XFEL) is a powerful method to address dynamic changes in electronic states and structures of photocatalysts in the excited state in ultrafast short time scales. The ultrafast atomic-scale local structural change in photoexcited WO3 was observed by W L1 edge XAFS spectroscopy using an XFEL. An anisotropic local distortion around the W atom could reproduce well the spectral features at a delay time of 100 ps after photoexcitation based on full potential multiple scattering calculations. The distortion involved the movement of W to shrink the shortest W-O bonds and elongate the longest one. The movement of the W atom could be explained by the filling of the dxy and dzx orbitals, which were originally located at the bottom of the conduction band with photoexcited electrons.

Ambient Pressure Hard X-ray Photoelectron Spectroscopy for Functional Material Systems as Fuel Cells under Working Conditions.

Heterogeneous interfaces play important roles in a variety of functional material systems and technologies, such as catalysis, batteries, and devices. A fundamental understanding of efficient functions at interfaces under realistic conditions is crucial for sophisticated designs of useful material systems and novel devices. X-ray photoelectron spectroscopy is one of the most promising and common methods to investigate such material systems. Although X-ray photoelectron spectroscopy is usually conducted under high vacuum because of the requirement of electron detection with the precise measurement of kinetic energies, extensive efforts have been devoted to the measurements in gaseous environments. Very recently, we have succeeded in measuring X-ray photoelectron spectra under real ambient atmosphere (105 Pa), using synchrotron radiation hard X-rays with the photon energy of 8 keV and the windowless electron spectrometer system. In this Account, the novel useful technique of real ambient pressure hard X-ray photoelectron spectroscopy is reviewed. As examples of (near) ambient pressure hard X-ray photoelectron spectroscopy, hydrogen storage of Pd nanoparticles is at first investigated by recording Pd 3d and valence band spectra under hydrogen atmosphere. The Pd 3d and valence band spectra are found to change rather abruptly depending on the hydrogen pressure, demonstrating a behavior like phase transformation. Subsequently, as a main topic in this Account, we describe investigations of the electronic states of platinum nanoparticles on the cathode electrocatalyst in a polymer electrolyte fuel cell (PEFC) under the voltage operating conditions using the near ambient pressure hard X-ray photoelectron spectroscopic system. The Pt 4f and 3d X-ray photoelectron spectra of the cathode Pt/C catalysts clearly show that the oxidized Pt species is at most divalent and the tetravalent Pt species does not exist on the Pt nanoparticles even at the positive cathode-anode voltage of ∼1.4 V. Although the water oxidation reaction may take place at the potential, such a reaction does not lead to a buildup of detectable tetravalent Pt in the PEFC. The voltage-dependent Pt 3d X-ray photoelectron spectra show a clear hysteresis between the voltage increase and decrease processes. The fraction of oxidized Pt species matched the ratio of surface to total Pt atoms in the nanoparticles, which suggests that Pt oxidation occurs as a reaction event at only the first Pt layer of the Pt nanoparticles and the inner Pt atoms do not participate in the reaction practically. The developed technique is a valuable in situ tool for the investigation of the electronic states of PEFCs and other interesting functional material systems and devices under realistic working conditions.

SPring-8 BL36XU: Synchrotron Radiation X-Ray-Based Multi-Analytical Beamline for Polymer Electrolyte Fuel Cells under Operating Conditions.

We designed and constructed a beamline BL36XU at the 8 GeV synchrotron radiation facility SPring-8 to provide information required for the development of next-generation polymer electrolyte fuel cells (PEFCs) by clarifying the dynamic aspects of structures and electronic states of cathode catalysts under PEFC operating conditions and in the deterioration processes by accelerated durability test protcols. To investigate the mechanism and degradation process for the cathode electrocatalysis in practical PEFCs, we developed advanced time- and spatially-resolved in-situ/operando X-ray absorption fine structure measurement systems and complementary analytical systems (X-ray emission spectroscopy (XES), X-ray diffraction (XRD), X-ray computer tomography (CT) and hard X-ray photoelectron spectroscopy (HAXPES)) and combined them to develop multi-analytical systems at BL36XU. Multi-analytical systems are very powerful for observing spatial-temporal features of the transient processes occurring in complex systems such as PEFCs. This account describes the design, performance, and research results of the BL36XU and multi-analytical in-situ/operando systems.

Development of Surface Fluorescence X-Ray Absorption Fine Structure Spectroscopy Using a Laue-Type Monochromator.

Surface fluorescence X-ray absorption fine structure (XAFS) spectroscopy using a Laue-type monochromator has been developed to acquire structural information about metals with a very low concentrate on a flat highly oriented pyrolytic graphite (HOPG) surface in the presence of electrolytes. Generally, surface fluorescence XAFS spectroscopy is hindered by strong scattering from the bulk, which often chokes the pulse counting detector. In this work, we show that a bent crystal Laue analyzer (BCLA) can efficiently remove the scattered X-rays from the bulk even in the presence of solution. We applied the technique to submonolayer (∼1014  atoms cm-2 ) Pt on HOPG and successfully obtained high signal/noise in situ XAFS data in combination with back-illuminated fluorescence XAFS (BI-FXAFS) spectroscopy. This technique allows in situ XAFS measurements of flat electrode surfaces to be performed in the presence of electrolytes.

Reversible low-temperature redox activity and selective oxidation catalysis derived from the concerted activation of multiple metal species on Cr and Rh-incorporated ceria catalysts.

The ceria-based catalyst incorporated with Cr and a trace amount of Rh (Cr0.19Rh0.06CeOz) was prepared and the reversible redox performances and oxidation catalysis of CO and alcohol derivatives with O2 at low temperatures (<373 K) were investigated. In situ X-ray absorption fine structure (XAFS), ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM)-EDS/EELS and temperature-programmed reduction/oxidation (TPR/TPO) revealed the structures and redox mechanisms of three metals in Cr0.19Rh0.06CeOz: dispersed Rh3+δ species (<1 nm) and Cr6-γO3-x nanoparticles (∼1 nm) supported on CeO2 in Cr0.19Rh0.06CeOz were transformed to Rh nanoclusters, Cr(OH)3 species and CeO2-x with two Ce3+-oxide layers at the surface in a concerted activation manner of the three metal species with H2.

Nonlinear Spectroscopy with X-Ray Two-Photon Absorption in Metallic Copper.

X-ray two-photon absorption (TPA) spectrum of metallic copper is measured using a free-electron laser (XFEL). The spectrum differs from that measured by the conventional one-photon absorption (OPA), and characterized by a peak below the Fermi level, which is assigned to the transition to the 3d state. The impact of the XFEL pulse on the OPA spectrum is discussed by analyzing the pulse-energy dependence, which indicates that the intrinsic TPA spectrum is measured.

Controlled Modification of Superconductivity in Epitaxial Atomic Layer-Organic Molecule Heterostructures.

Self-assembled organic molecules can potentially be an excellent source of charge and spin for two-dimensional (2D) atomic-layer superconductors. Here we investigate 2D heterostructures based on In atomic layers epitaxially grown on Si and highly ordered metal-phthalocyanine (MPc, M = Mn, Cu) through a variety of techniques: scanning tunneling microscopy, electron transport measurements, angle-resolved photoemission spectroscopy, X-ray magnetic circular dichroism, and ab initio calculations. We demonstrate that the superconducting transition temperature (Tc) of the heterostructures can be modified in a controllable manner. Particularly, the substitution of the coordinated metal atoms from Mn to Cu is found to reverse the Tc shift from negative to positive directions. This distinctive behavior is attributed to a competition of charge and spin effects, the latter of which is governed by the directionality of the relevant d-orbitals. The present study shows the effectiveness of molecule-induced surface doping and the significance of microscopic understanding of the molecular states in these 2D heterostructures.

Large-Gap Magnetic Topological Heterostructure Formed by Subsurface Incorporation of a Ferromagnetic Layer.

Inducing magnetism into topological insulators is intriguing for utilizing exotic phenomena such as the quantum anomalous Hall effect (QAHE) for technological applications. While most studies have focused on doping magnetic impurities to open a gap at the surface-state Dirac point, many undesirable effects have been reported to appear in some cases that makes it difficult to determine whether the gap opening is due to the time-reversal symmetry breaking or not. Furthermore, the realization of the QAHE has been limited to low temperatures. Here we have succeeded in generating a massive Dirac cone in a MnBi2Se4/Bi2Se3 heterostructure, which was fabricated by self-assembling a MnBi2Se4 layer on top of the Bi2Se3 surface as a result of the codeposition of Mn and Se. Our experimental results, supported by relativistic ab initio calculations, demonstrate that the fabricated MnBi2Se4/Bi2Se3 heterostructure shows ferromagnetism up to room temperature and a clear Dirac cone gap opening of ∼100 meV without any other significant changes in the rest of the band structure. It can be considered as a result of the direct interaction of the surface Dirac cone and the magnetic layer rather than a magnetic proximity effect. This spontaneously formed self-assembled heterostructure with a massive Dirac spectrum, characterized by a nontrivial Chern number C = -1, has a potential to realize the QAHE at significantly higher temperatures than reported up to now and can serve as a platform for developing future "topotronics" devices.

Non-contact electric potential measurements of electrode components in an operating polymer electrolyte fuel cell by near ambient pressure XPS.

Photoelectron spectroscopy has the advantage of providing electric potentials by non-contact measurements based on the kinetic energy shift in component potential. We performed operando hard X-ray photoelectron spectroscopy (HAXPES) measurements with an 8 keV excitation source to measure the shift in electron kinetic energies as a function of the voltages of all the components at the anode and cathode electrodes of a polymer electrolyte fuel cell (PEFC). At the cathode electrode, when we increase the voltage between the cathode and anode from 0.2 to 1.2 V, the O 1s and F 1s peaks shift to a lower binding energy and the magnitude of the energy shift is equal to the voltage. The Pt 3d and C 1s peaks do not shift with the voltage since platinum nanoparticles and carbon supports at the cathode electrode have ground contact. In contrast to the cathode electrode, the peak shifts of all the components at the anode electrode show the same amount of shift as the voltages. It is clear that the change in the potential difference occurs only in an electrical double layer at the interface between the cathode electrode (Pt/C) and the electrolyte (Nafion and water), and that the anode electrode is in equilibrium as a pseudo-hydrogen electrode. Moreover, the electric potential variation of the cathode electrode in a PEFC under a power generation condition was also directly detected by operando HAXPES.

In situ study of oxidation states of platinum nanoparticles on a polymer electrolyte fuel cell electrode by near ambient pressure hard X-ray photoelectron spectroscopy.

We performed in situ hard X-ray photoelectron spectroscopy (HAXPES) measurements of the electronic states of platinum nanoparticles on the cathode electrocatalyst of a polymer electrolyte fuel cell (PEFC) using a near ambient pressure (NAP) HAXPES instrument having an 8 keV excitation source. We successfully observed in situ NAP-HAXPES spectra of the Pt/C cathode catalysts of PEFCs under working conditions involving water, not only for the Pt 3d states with large photoionization cross-sections in the hard X-ray regime but also for the Pt 4f states and the valence band with small photoionization cross-sections. Thus, this setup allowed in situ observation of a variety of hard PEFC systems under operating conditions. The Pt 4f spectra of the Pt/C electrocatalysts in PEFCs clearly showed peaks originating from oxidized Pt(ii) at 1.4 V, which unambiguously shows that Pt(iv) species do not exist on the Pt nanoparticles even at such large positive voltages. The water oxidation reaction might take place at that potential (the standard potential of 1.23 V versus a standard hydrogen electrode) but such a reaction should not lead to a buildup of detectable Pt(iv) species. The voltage-dependent NAP-HAXPES Pt 3d spectra revealed different behaviors with increasing voltage (0.6 → 1.0 V) compared with decreasing voltage (1.0 → 0.6 V), showing a clear hysteresis. Moreover, quantitative peak-fitting analysis showed that the fraction of non-metallic Pt species matched the ratio of the surface to total Pt atoms in the nanoparticles, which suggests that Pt oxidation only takes place at the surface of the Pt nanoparticles on the PEFC cathode, and the inner Pt atoms do not participate in the reaction. In the valence band spectra, the density of electronic states near the Fermi edge reduces with decreasing particle size, indicating an increase in the electrocatalytic activity. Additionally, a change in the valence band structure due to the oxidation of platinum atoms was also observed at large positive voltages. The developed apparatus is a valuable in situ tool for the investigation of the electronic states of PEFC electrocatalysts under working conditions.

Dynamics of Photoelectrons and Structural Changes of Tungsten Trioxide Observed by Femtosecond Transient XAFS.

The dynamics of the local electronic and geometric structures of WO3 following photoexcitation were studied by femtosecond time-resolved X-ray absorption fine structure (XAFS) spectroscopy using an X-ray free electron laser (XFEL). We found that the electronic state was the first to change followed by the local structure, which was affected within 200 ps of photoexcitation.

Visualization of the heterogeneity of cerium oxidation states in single Pt/Ce2Zr2O(x) catalyst particles by nano-XAFS.

The cerium oxidation states in single catalyst particles of Pt/Ce2Zr2O(x) (x=7 to 8) were investigated by spatially resolved nano X-ray absorption fine structure (nano-XAFS) using an X-ray nanobeam. Differences in the distribution of the Ce oxidation states between Pt/Ce2Zr2O(x) single particles of different oxygen compositions x were visualized in the obtained two-dimensional X-ray fluorescent (XRF) mapping images and the Ce L(III)-edge nano X-ray absorption near-edge structure (nano-XANES) spectra.

Anisotropic thermal expansion and cooperative Invar and anti-Invar effects in mn alloys.

We have investigated thermal expansion of a tetragonal Mn(88)Ni(12) alloy by x-ray diffraction, Mn and Ni K-edge extended x-ray-absorption fine-structure spectroscopy, and the computational simulations based on the path-integral effective-classical-potential theory. It is found from the x-ray diffraction that the tetragonal lattice constant c exhibits almost no thermal expansion like an Invar alloy, while the lattice constant a shows even larger thermal expansion than usually expected from anharmonicity, implying significant anisotropy in thermal expansion. The extended x-ray-absorption fine-structure reveals that the Mn local environment is actually tetragonally distorted, while the Ni one retains its inherent cubiclike symmetry. Combined with the computational simulations, it is concluded that large thermal expansion along the a axis originates from the anti-Invar effect, while negligibly small thermal expansion along the c axis originates from the cooperative Invar effect. Namely, the tetragonally distorted more stable antiferromagnetic Mn state gives a significantly smaller (slightly longer) atomic radius along the a (c) axis than the radius of the spherical paramagnetic state.

Structural kinetics of a Pt/C cathode catalyst with practical catalyst loading in an MEA for PEFC operating conditions studied by in situ time-resolved XAFS.

The structural kinetics of surface events on a Pt/C cathode catalyst in a membrane electrode assembly (MEA) with a practical catalyst loading (0.5 mgPt cm(-2)) for a polymer electrolyte fuel cell were investigated by in situ time-resolved X-ray absorption fine structure analysis (XAFS; time resolution: 100 ms) for the first time. The rate constants of structural changes in the Pt/C cathode catalyst in the MEA during voltage cycling were successfully estimated. For voltage-cycling processes, all reactions (electrochemical reactions and structural changes in the Pt catalyst) in the MEA were found to be much faster than those in an MEA with a thick cathode catalyst layer, but the in situ time-resolved XAFS analysis revealed that significant time lags similarly existed between the electrochemical reactions and the structural changes in the Pt cathode catalyst. The time-resolved XAFS also revealed differences in the structural kinetics of the Pt/C cathode catalyst for the voltage-cycling processes under N2 and air flows at the cathode.

A Case of Recurrent Verruconis gallopava Infection at One Year after Excision of a Solitary Pulmonary Lesion.

We herein report a case of recurrent infection caused by Verruconis gallopava, which is known to cause fatal phaeohyphomycosis. A 71-year-old man presented with a fever, and computed tomography revealed right chest wall thickening. Eleven years earlier, he had undergone autologous peripheral blood stem cell transplantation for a hematological malignancy. One year earlier, he had undergone excision of a solitary pulmonary nodule, from which had been detected V. gallopava. On this occasion, right chest wall surgery was performed to investigate the cause of the fever, which led to the diagnosis of recurrent infection. Even if a localized lesion is excised, additional antifungal therapy should be performed.

Pt17 nanocluster electrocatalysts: preparation and origin of high oxygen reduction reaction activity.

We recently found that [Pt17(CO)12(PPh3)8]z (Pt = platinum; CO = carbon monoxide; PPh3 = triphenylphosphine; z = 1+ or 2+) is a Pt nanocluster (Pt NC) that can be synthesized with atomic precision in air. The present study demonstrates that it is possible to prepare a Pt17-supported carbon black (CB) catalyst (Pt17/CB) with 2.1 times higher oxygen reduction reaction (ORR) activity than commercial Pt nanoparticles/CB by the adsorption of [Pt17(CO)12(PPh3)8]z onto CB and subsequent calcination of the catalyst. Density functional theory calculation strongly suggests that the high ORR activity of Pt17/CB originates from the surface Pt atoms that have an electronic structure appropriate for the progress of ORR. These results are expected to provide design guidelines for the fabrication of highly active ORR catalysts using Pt NCs with a diameter of about 1 nm and thereby enabling the use of reduced amounts of Pt in polymer electrolyte fuel cells.