Adenosquamous Carcinoma of the Choledochus

The patient was an 86-year-old man who was admitted with obstructive jaundice. Computed tomography revealed a tumor in the hilar choledochus with peripheral hepatic duct dilatation. Endoscopic cholangiography (ERC) demonstrated the defect in the choledochus. Brushing cytology during ERC showed Orange-G-philic keratinized atypical cells, which led to a diagnosis of squamous cell carcinoma. Chemotherapy with tegafur-gimeracil-oteracil potassium was ineffective and was discontinued due to adverse effects. The patient died 5 months after the diagnosis and autopsy revealed tubular adenocarcinoma of the hilar bile duct with squamous cell carcinoma component. Progression of the disease might influence the distribution of adenosquamous carcinoma. The clinicopathological sequence of adenosquamous carcinoma of the choledochus was documented

Premodified Surface Method to Obtain Ultra-Highly Dispersed Metals and their 3D Structure Control on an Oxide Single-Crystal Surface

Precise control of the three-dimensional (3D) structure of highly dispersed metal species such as metal complexes and clusters attached to an oxide surface has been important for the development of next-generation high-performance heterogeneous catalysts. However, this is not easily achieved for the following reasons. (1) Metal species are easily aggregated on an oxide surface, which makes it difficult to control their size and orientation definitely. (2) Determination of the 3D structure of the metal species on an oxide powder surface is hardly possible. To overcome these difficulties, we have developed the premodified surface method, where prior to metal deposition, the oxide surface is premodified with a functional organic molecule that can strongly coordinate to a metal atom. This method has successfully provided a single metal dispersion on an oxide single-crystal surface with the 3D structure precisely determined by polarization-dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS). Here we describe our recent results on ultra-high dispersions of various metal atoms on TiO2(110) surfaces premodified with mercapto compounds, and show the possibility of fine tuning and orientation control of the surface metal 3D structures

Stability of underpotentially deposited Ag layers on a Au(111) surface studied by surface X-ray scattering

Stability of underpotentially deposited (upd) Ag layers on Au(111) surface was investigated by surface X-ray scattering (SXS). While the complete pseudomorphic Ag bilayer on Au(111) surface obtained by upd at 10 mV (vs. Ag/Ag+) was maintained its structure even after the circuit was disconnected and the surface was exposed to ambient atmosphere, the pseudomorphic Ag monolayer obtained by upd at 50 mV was converted to a partial bilayer with the coverage of 0.66 ML and 0.46 ML for the 1st and 2nd layer, respectively. These results show that Ag bilayer is structurally more stable than Ag monolayer on Au(111) and Ag atoms of the upd monolayer move around on the Au(111) surface without potential control

Photoanodic formation of an organic monolayer on a hydrogen-terminated Si(111) surface via Si–C covalent bond using a Grignard reagent and its application for one-step monolayer-patterning

Alkyl monolayer (octadecyl) was formed on a hydrogen-terminated Si(1 1 1) (H–Si(1 1 1)) electrode via Si–C covalent bond by photoanodic reaction with C18H37MgCl in THF solution. The formation of the organic monolayer was confirmed by attenuated total reflection (ATR) FT-IR spectroscopy. This process was applied to a one-step patterning of an organic monolayer on a H–Si(1 1 1) by illuminating the H–Si(1 1 1) electrode through photomask in a C18H37MgCl/THF solution at positive potential. The formation of the pattern reflecting the shape of the photomask was confirmed by SEM observations

In situ Real-time Monitoring of Electrochemical Ag Deposition on a Reconstructed Au(111) Surface Studied by Scanning Tunneling Microscopy

Electrochemical deposition of Ag on a 23 × √3 reconstructed surface of Au(111) electrode at various potentials was followed by scanning tunneling microscopy (STM) in situ in real time. At −0.2 V (vs Ag/AgCl), line shaped Ag deposits with the height of 0.46 ± 0.03 nm, which is equivalent to 2 atomic height, were observed. The center of each Ag line was located in the hcp domain of the reconstructed structure. They then grew two-dimensionally so that the other regions, i.e., bridge and fcc domains, of the reconstructed Au surface were gradually covered with the Ag bilayer. As the deposition proceeded, another Ag layer started to nucleate and grow on the Ag bilayer. This layer was one atomic height and grew not linearly but two-dimensionally from the beginning. At 0.3 V, the monatomic layer of Ag was formed preferentially in the hcp domain and the Ag growth stopped at ca. 1 ML. The potential dependent stabilities of the deposited bi- and mono-atomic Ag layers were confirmed by the potential step measurements. The structural conversion from the bi- to mono-atomic layer of Ag was observed when the potential was stepped from −0.2 to +0.3 V. At 0 V, an intermediate potential, both the bi- and mono-atomic Ag layers were observed at the initial stage of Ag deposition. These results revealed that the biatomic Ag layer was more favored at more negative potentials in the range of −0.2 to +0.3 V. The growth mode of the potentiostatic electrochemical deposition of Ag on the reconstructed Au (111) electrode surface observed in this study is quite different from those previously reported for the electrochemical deposition on the reconstruction-lifted Au(111) electrode surface and deposition under ultrahigh vacuum (UHV) condition on the reconstructed Au(111) surface, showing the importance of structure of substrate surface and electrode potential on the growth mode

Electrodeposition of Ag and Pd on a reconstructed Au(111) electrode surface studied by in situ scanning tunneling microscopy

Electrochemical deposition of Ag and potential-induced structural change of the deposited Ag layer on a 23 x √3 reconstructed surface of Au(111) electrode were followed by in situ scanning tunneling microscope (STM). A uniform Ag monolayer was formed on a reconstructed Au(111) surface in a 50 mM H2SO4 solution at +0.3 V (vs. Ag/AgCl) after adding a solution containing Ag2SO4 so that the concentration of Ag+ in the STM cell became ca. 2 μM. No characteristic height corrugation such as the Au reconstruction was observed on the surface, indicating that the lifting of the substrate Au reconstruction occurred by Ag deposition. The formed Ag monolayer was converted to a net-like shaped Ag nano-pattern of biatomic height when the potential was stepped from +0.3 V to -0.2 V in the solution containing 2 μM Ag+. This result indicates that the substrate Au(111)-(1 x 1) surface was converted to the reconstructed surface even in the presence of Ag adlayer. Quite different structure was observed for Pd deposition on a reconstructed surface of Au(111) electrode at +0.3 V and the origin for this difference between Ag and Pd deposition are discussed

Density function theoretical investigation on the Ni3PP structure and the hydrogen adsorption property of the Ni2P(0001) surface

The electronic and structural properties of a phosphorus-terminated structure of Ni2P(0001) surface (Ni3PP) are investigated by density functional theory (DFT) calculations. Phosphorus adsorption largely stabilizes the Ni2P(0001) surface by creating Ni-P bonds on the Ni trimer. Atomic hydrogen can adsorb on the topmost P site although its adsorption energy is much lower than its adsorption energy on the Ni trimer site of the Ni3P2 surface. Our results suggest that the Ni trimer is the key factor for high catalytic activity

Machine-learning prediction of the d-band center for metals and bimetals

The d-band center for metals has been widely used in order to understand activity trends in metal-surface-catalyzed reactions in terms of the linear Bronsted-Evans-Polanyi relation and Hammer-Norskov d-band model. In this paper, the d-band centers for eleven metals (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Au) and their pairwise bimetals for two different structures (1% metal doped- or overlayer-covered metal surfaces) are statistically predicted using machine learning methods from readily available values as descriptors for the target metals (such as the density and the enthalpy of fusion of each metal). The predictive accuracy of four regression methods with different numbers of descriptors and different test-set/training-set ratios are quantitatively evaluated using statistical cross validations. It is shown that the d-band centers are reasonably well predicted by the gradient boosting regression (GBR) method with only six descriptors, even when we predict 75% of the data from only 25% given for training (average root mean square error (RMSE) < 0.5 eV). This demonstrates a potential use of machine learning methods for predicting the activity trends of metal surfaces with a negligible CPU time compared to first-principles methods

Electrocatalytic Activity for Oxygen Reduction of Multilayer of Pd Coated Gold Nanoclusters

Multilayers of SAM (Self-Assembled Monolayer)-protected gold nanoc1usters (GNCs) were constructed by utilizing electrostatic interaction between cationic polymer (poly allylamine hydrochloride: PAH) and GNCs protected by SAM with anionic carboxyl groups (Mercaptoundecanoic acid: MUA). Electrocatalytically active metal multilayers were formed by depositing small amount of foreign metals on GNCs after removing the SAM. We estimated electrocatalytic properties of GNC multilayers by oxygen reductions