Iridium-Cooperated, Symmetry-Broken Manganese Oxide Nanocatalyst for Water Oxidation.

The water oxidation reaction, the most important reaction for hydrogen production and other sustainable chemistry, is efficiently catalyzed by the Mn4CaO5 cluster in biological photosystem II. However, synthetic Mn-based heterogeneous electrocatalysts exhibit inferior catalytic activity at neutral pH under mild conditions. Symmetry-broken Mn atoms and their cooperative mechanism through efficient oxidative charge accumulation in biological clusters are important lessons but synthesis strategies for heterogeneous electrocatalysts have not been successfully developed. Here, we report a crystallographically distorted Mn-oxide nanocatalyst, in which Ir atoms break the space group symmetry from I41/amd to P1. Tetrahedral Mn(II) in spinel is partially replaced by Ir, surprisingly resulting in an unprecedented crystal structure. We analyzed the distorted crystal structure of manganese oxide using TEM and investigated how the charge accumulation of Mn atoms is facilitated by the presence of a small amount of Ir.

Inorganic Hollow Nanocoils Fabricated by Controlled Interfacial Reaction and Their Electrocatalytic Properties.

The fabrication of 3D hollow nanostructures not only allows the tactical provision of specific physicochemical properties but also broadens the application scope of such materials in various fields. The synthesis of 3D hollow nanocoils (HNCs), however, is limited by the lack of an appropriate template or synthesis method, thereby restricting the wide-scale application of HNCs. Herein, a strategy for preparing HNCs by harnessing a single sacrificial template to modulate the interfacial reaction at a solid-liquid interface that allows the shape-regulated transition is studied. Furthermore, the triggering of the Kirkendall effect in 3D HNCs is demonstrated. Depending on the final state of the transition metal ions reduced during the electrochemical preparation of HNCs, the surface states of the binding anions and the composition of the HNCs can be tuned. In a single-component CrPO4 HNC with a clean surface, the Kirkendall effect of the coil shape is analyzed at various points throughout the reaction. The rough-surface multicomponent MnOx P0.21 HNCs are complexed with ligand-modified BF4 -Mn3 O4 nanoparticles. The fabricated nanocomposite exhibits an overpotential decrease of 25 mV at neutral pH compared to pure BF4 -Mn3 O4 nanoparticles because of the increased active surface area.

Electrochemical Synthesis of Glycine from Oxalic Acid and Nitrate.

In manufacturing C-N bond-containing compounds, it is an important challenge to alternate the conventional methodologies that utilize reactive substrates, toxic reagents, and organic solvents. In this study, we developed an electrochemical method to synthesize a C-N bond-containing molecule avoiding the use of cyanides and amines by harnessing nitrate (NO3- ) as a nitrogen source in an aqueous electrolyte. In addition, we utilized oxalic acid as a carbon source, which can be obtained from electrochemical conversion of CO2. Thus, our approach can provide a route for the utilization of anthropogenic CO2 and nitrate wastes, which cause serious environmental problems including global warming and eutrophication. Interestingly, the coreduction of oxalic acid and nitrate generated reactive intermediates, which led to C-N bond formation followed by further reduction to an amino acid, namely, glycine. By carefully controlling this multireduction process with a fabricated Cu-Hg electrode, we demonstrated the efficient production of glycine with a faradaic efficiency (F.E.) of up to 43.1 % at -1.4 V vs. Ag/AgCl (current density≈90 mA cm-2 ).

A wafer-like apparatus for two-dimensional measurement of plasma parameters and temperature distribution in low-temperature plasmas.

A wafer-type monitoring apparatus that can simultaneously measure the two-dimensional (2D) distributions of substrate temperature and plasma parameters is developed. To measure the temperature of the substrate, a platinum resistance temperature detector is used. The plasma density and electron temperature are obtained using the floating harmonics method, and incoming heat fluxes from the plasma to the substrate are obtained from the plasma density and electron temperature. In this paper, 2D distributions of the substrate temperature, plasma density, and electron temperature are obtained simultaneously for the first time in inductively coupled plasma. The shapes of the 2D distributions of the substrate temperature and incoming heat flux are similar to each other, but some differences are found. To understand that, an energy balance equation for the substrate is established, which shows good agreement with the experimental results. This apparatus will promote the understanding of surface reactions, which are very sensitive to the temperatures and plasma densities in plasma processing.

Capturing Manganese Oxide Intermediates in Electrochemical Water Oxidation at Neutral pH by In Situ Raman Spectroscopy.

Electrochemical water splitting is a promising means to produce eco-friendly hydrogen fuels. Inspired by the Mn4 CaO5 cluster in nature, substantial works have been performed to develop efficient manganese (Mn)-based heterogeneous catalysts. Despite improvements in catalytic activity, the underlying mechanism of the oxygen evolution reaction (OER) is not completely elucidated owing to the lack of direct spectroscopic evidence for the active Mn-oxo moieties. We identify water oxidation intermediates on the surface of Mn3 O4 nanoparticles (NPs) in the OER at neutral pH by in situ Raman spectroscopy. A potential-dependent Raman peak was detected at 760 cm-1 and assigned to the active MnIV =O species generated during water oxidation. Isotope-labeling experiments combined with scavenger experiments confirmed the generation of surface terminal MnIV =O intermediates in the Mn-oxide NPs. This study provides an insight into the design of systems for the observation of reaction intermediates.

Spectroscopic capture of a low-spin Mn(IV)-oxo species in Ni-Mn3O4 nanoparticles during water oxidation catalysis.

High-valent metal-oxo moieties have been implicated as key intermediates preceding various oxidation processes. The critical O-O bond formation step in the Kok cycle that is presumed to generate molecular oxygen occurs through the high-valent Mn-oxo species of the water oxidation complex, i.e., the Mn4Ca cluster in photosystem II. Here, we report the spectroscopic characterization of new intermediates during the water oxidation reaction of manganese-based heterogeneous catalysts and assign them as low-spin Mn(IV)-oxo species. Recently, the effects of the spin state in transition metal catalysts on catalytic reactivity have been intensely studied; however, no detailed characterization of a low-spin Mn(IV)-oxo intermediate species currently exists. We demonstrate that a low-spin configuration of Mn(IV), S = 1/2, is stably present in a heterogeneous electrocatalyst of Ni-doped monodisperse 10-nm Mn3O4 nanoparticles via oxo-ligand field engineering. An unprecedented signal (g = 1.83) is found to evolve in the electron paramagnetic resonance spectrum during the stepwise transition from the Jahn-Teller-distorted Mn(III). In-situ Raman analysis directly provides the evidence for Mn(IV)-oxo species as the active intermediate species. Computational analysis confirmed that the substituted nickel species induces the formation of a z-axis-compressed octahedral C4v crystal field that stabilizes the low-spin Mn(IV)-oxo intermediates.

Alternative Regional Flaps When Anterolateral Thigh Flap Perforator is not Feasible.

This paper presents the scheme to select alternative flaps limited to the region of the ipsilateral thigh when the perforator of the anterolateral thigh flap is not feasible. Total of 564 consecutive microsurgery cases using anterolateral thigh perforator flap was reviewed from March of 2001 to January of 2009. Total of 12 cases used a contingent flap due to anatomical and technical complications of the anterolateral thigh perforator. The alternatives were skin perforator flaps adjacent to the initial flap (3 cases of upper anterolateral thigh flap, 4 cases of anteromedial thigh flap), vastus lateralis muscle flap with skin graft (2 cases), and anterolateral thigh flap as septocutaneous flap without a prominent perforator on the septum (3 cases). All flaps survived and provided coverage as planned but one case using septocutaneous flap without a prominent perforator was noted with partial necrosis. Adjacent flaps around the anterolateral thigh perforator flap may provide useful alternative flaps in cases of failed elevation. Limiting the contingent secondary flap to this region may reduce further donor site morbidity and still provide an adequate flap for reconstruction.

Giant lymphangioma of the tongue.

This report presents the treatment of an extensive lymphatic malformation of the tongue. Sclerosing agents are now widely used as the first-line treatment of lymphatic malformation. However, treatment of lymphatic malformation involving the face and the vital structures such as the airway remains to be challenging. A 4-year-old boy underwent a total of 15 OK-432 injection sclerotherapy treatments over a 2-year period, having slow progress until sudden enlargement of the tongue was noted shortly after the last injection. Partial excision of the lesion was performed. This case demonstrates the risk in treating large microcystic lymphatic malformation of the tongue with sclerotherapy and provides an insight in the management protocol.

Production of gamma-aminobutyric acid in black raspberry juice during fermentation by Lactobacillus brevis GABA100.

Black raspberry juice was fermented to produce gamma-aminobutyric acid (GABA) using lactic acid bacteria (Lactobacillus brevis GABA 100) at different temperatures (25, 30, or 37 degrees C) and pHs (3.5, 4, 4.5, 5, 5.5, or 6) for 15 days. Concentrations of GABA in the juices were determined during fermentation using HPLC. GABA was produced continuously even if the viable bacterial counts markedly decreased. The fermentation at 30 degrees C generally showed higher production of GABA in the juices than those at 25 and 37 degrees C. The GABA in the juices fermented at 30 degrees C reached the maximum levels on the 12th day. The juices fermented at lower pH and lower temperature showed a lower degradation of monomeric anthocyanins. The results suggest that black raspberry juice can be GABA enriched using lactic acid bacteria.