Mechanism of H+ dissociation-induced O-O bond formation via intramolecular coupling of vicinal hydroxo ligands on low-valent Ru(III) centers.

The understanding of O-O bond formation is of great importance for revealing the mechanism of water oxidation in photosynthesis and for developing efficient catalysts for water oxidation in artificial photosynthesis. The chemical oxidation of the RuII2(OH)(OH2) core with the vicinal OH and OH2 ligands was spectroscopically and theoretically investigated to provide a mechanistic insight into the O-O bond formation in the core. We demonstrate O-O bond formation at the low-valent RuIII2(OH) core with the vicinal OH ligands to form the RuII2(µ-OOH) core with a µ-OOH bridge. The O-O bond formation is induced by deprotonation of one of the OH ligands of RuIII2(OH)2 via intramolecular coupling of the OH and deprotonated O- ligands, conjugated with two-electron transfer from two RuIII centers to their ligands. The intersystem crossing between singlet and triple states of RuII2(µ-OOH) is easily switched by exchange of H+ between the µ-OOH bridge and the auxiliary backbone ligand.

Configurationally Nonselective Aquation of a Mononuclear Ru(II) Chloro Complex to Aquo Complex Isomers with Distinctive Aspects in Photoisomerization, Redox, and Catalytic Water Oxidation.

distal-[Ru(EtOtpy)(pynp)Cl]+ (d-EtO1Cl) (EtOtpy = 4'-ethoxy-2,2':6',2″-terpyridine, pynp = 2-(2-pyridyl)-1,8-naphthyridine), and distal/proximal-[Ru(EtOtpy)(pynp)OH2]2+ (d/p-EtO1H2O) complexes were newly synthesized to investigate the synergistic influence of the geometric configuration coupled with substituent introduction of an ethoxy (EtO) group on the physicochemical properties and reactions of the Ru(II) complexes. Configurationally nonselective aquation of d-EtO1Cl was uniquely observed to form d/p-EtO1H2O isomers in water, in contrast to configurationally selective aquation of distal-[Ru(tpy)(pynp)Cl]+ (d-1Cl, tpy = 2,2':6',2″-terpyridine) without the EtO group [Yamazaki, H. . J. Am. Chem. Soc. 2011, 133, 8846-8849].The kinetic profiles of the aquation reactions of d-EtO1Cl were well analyzed using a sequential reversible reaction model assuming the reversible interconversion between d/p-EtO1H2O isomers via d-EtO1Cl. The observed equilibrium constant (Kiso) of isomerization between p/d-EtO1H2O was calculated from the kinetic analysis as Kiso = 0.45, which is consistent with the final concentration ratio (1:0.43) of p/d-EtO1H2O generated in the aquation reaction of d-EtO1Cl. The irreversible photoisomerization from d-EtO1H2O to p-EtO1H2O was observed in water with an internal quantum yield (Φ) of 0.44% at 520 nm. Electrochemical measurements showed that d-EtO1H2O undergoes a 2-step oxidation reaction of 1H+-coupled 1e- processes of RuII-OH2/RuIII-OH and RuIII-OH/RuIV═O at pH 1.3-9.7, whereas p-EtO1H2O undergoes a 1-step oxidation reaction of a 2H+-coupled 2e- process of RuII-OH2/RuIV═O in the pH range of 1.8-11.5. Any redox potential of d/p-EtO1H2O isomers was decreased by the electro-donating EtO substitution, compared with distal/proximal-[Ru(tpy)(pynp)OH2]2+ (d/p-1H2O). The turnover frequency (kO2 = 1.7 × 10-2 s-1) of d-EtO1H2O for water oxidation catalysis is higher than that (3.5 × 10-4 s-1) of p-EtO1H2O by a factor of 48.6. The kO2 value (1.7 × 10-2 s-1) for d-EtO1H2O is 4.5-fold higher than those of d-1H2O (3.8 × 10-3 s-1). The higher kO2 value of d-EtO1H2O compared with d-1H2O could be explained by the fast oxidation rate from RuIV═O to RuV═O involved in the rate-determining step due to the electron-donating EtO group.

Distinctive Aspects in Aquation, Proton-Coupled Redox, and Photoisomerization Reactions between Geometric Isomers of Mononuclear Ruthenium Complexes with a Large-π-Conjugated Tetradentate Ligand.

Geometric isomers of mononuclear ruthenium(II) complexes, distal-/proximal-[Ru(tpy)(dpda)Cl]+ (d-/p-RuCl, tpy = 2,2':6',2″-terpyridine, dpda = 2,7-bis(2-pyridyl)-1,8-diazaanthracene), were newly synthesized to comprehensively investigate the geometric and electronic structures and distinctive aspects in various reactions between isomers. The ultraviolet (UV)-visible absorption spectra of d-/p-RuCl isomers show intense bands for metal-to-ligand charge transfer (MLCT) at close wavelengths of 576 and 573 nm, respectively. However, time-dependent density functional theory (TD-DFT) calculations suggest that the MLCT transition of d-RuCl involves mainly single transitions to the π* orbital of the dpda ligand in contrast to mixing of the π* orbitals of the dpda and tpy ligands for p-RuCl. The aquation reaction (1.5 × 10-3 s-1) of p-RuCl to yield proximal-[Ru(tpy)(dpda)(OH2)]2+ (p-RuH2O) is faster than that (5.3 × 10-6 s-1) of d-RuCl in D2O/CD3OD (4:1 v/v) by three orders of magnitude, which resulted from the longer Ru-Cl bond by 0.017 Å and the distorted angle (100.2(3)°) of Cl-Ru-N (a nitrogen of dpda, being on a tpy plane) due to the steric repulsion between Cl and dpda for p-RuCl. Electrochemical measurements showed that d-RuH2O undergoes a 2-step oxidation reaction of 1H+-coupled 1e- processes of RuII-OH2/RuIII-OH and RuIII-OH/RuIV═O at pH 1-9, whereas p-RuH2O undergoes a 1-step oxidation reaction of a 2H+-coupled 2e- process of RuII-OH2/RuIV═O in the pH range of pH 1-10. The irreversible photoisomerization from d-RuH2O to p-RuH2O was observed in aqueous solution with an internal quantum yield (Φ) of 5.4 × 10-3% at 520 nm, which is lower compared with Φ = 1.1-2.1% of mononuclear Ru(II) aquo complexes with similar bidentate ligands instead of dpda by three orders of magnitude. This is possibly ascribed to the faster nonradiative decay rate from the excited 3MLCT state to the ground state for d-RuH2O due to the lower π* level of dpda ligands according to the energy-gap law: the rate decreases exponentially with the increasing energy gap.

Early intubation and decreased in-hospital mortality in patients with coronavirus disease 2019.

BACKGROUND: Some academic organizations recommended that physicians intubate patients with COVID-19 with a relatively lower threshold of oxygen usage particularly in the early phase of pandemic. We aimed to elucidate whether early intubation is associated with decreased in-hospital mortality among patients with novel coronavirus disease 2019 (COVID-19) who required intubation. METHODS: A multicenter, retrospective, observational study was conducted at 66 hospitals in Japan where patients with moderate-to-severe COVID-19 were treated between January and September 2020. Patients who were diagnosed as COVID-19 with a positive reverse-transcription polymerase chain reaction test and intubated during admission were included. Early intubation was defined as intubation conducted in the setting of ≤ 6 L/min of oxygen usage. In-hospital mortality was compared between patients with early and non-early intubation. Inverse probability weighting analyses with propensity scores were performed to adjust patient demographics, comorbidities, hemodynamic status on admission and time at intubation, medications before intubation, severity of COVID-19, and institution characteristics. Subgroup analyses were conducted on the basis of age, severity of hypoxemia at intubation, and days from admission to intubation. RESULTS: Among 412 patients eligible for the study, 110 underwent early intubation. In-hospital mortality was lower in patients with early intubation than those with non-early intubation (18 [16.4%] vs. 88 [29.1%]; odds ratio, 0.48 [95% confidence interval 0.27-0.84]; p = 0.009, and adjusted odds ratio, 0.28 [95% confidence interval 0.19-0.42]; p < 0.001). The beneficial effects of early intubation were observed regardless of age and severity of hypoxemia at time of intubation; however, early intubation was associated with lower in-hospital mortality only among patients who were intubated later than 2 days after admission. CONCLUSIONS: Early intubation in the setting of ≤ 6 L/min of oxygen usage was associated with decreased in-hospital mortality among patients with COVID-19 who required intubation. Trial Registration None.

Serial Passaging of RAW 264.7 Cells Modulates Intracellular AGE Formation and Downregulates RANKL-Induced In Vitro Osteoclastogenesis.

The passage number of cells refers to the number of subculturing processes that the cells have undergone. The effect of passage number on morphological and phenotypical characteristics of cells is of great importance. Advanced glycation end products have also been associated with cell functionality and characteristics. Murine monocyte RAW 264.7 cells differentiate into osteoclasts upon receptor activation caused by nuclear factor-kappa-Β ligand (RANKL) treatment. This study aims to identify the role of passage number on intracellular advanced glycation end products (AGEs) formation and osteoclastogenic differentiation of RAW 264.7 cells. Western blotting was performed to check intracellular AGE formation along with fluorometric analysis using a microplate reader. Tartrate-resistant acid phosphatase (TRAP) staining was performed to check osteoclastogenic differentiation, and qPCR was realized to check the responsible mRNA expression. Immunofluorescence was used to check the morphological changes. Intracellular AGE formation was increased with passaging, and the higher passage number inhibited multinucleated osteoclastogenic differentiation. Osteoclastogenic gene expression also showed a reducing trend in higher passages, along with a significant reduction in F-actin ring size and number. Lower passages should be used to avoid the effects of cell subculturing in in vitro osteoclastogenesis study using RAW 264.7 cells.

Potential Therapeutic Approach of Melatonin against Omicron and Some Other Variants of SARS-CoV-2.

The Omicron variant (B.529) of COVID-19 caused disease outbreaks worldwide because of its contagious and diverse mutations. To reduce these outbreaks, therapeutic drugs and adjuvant vaccines have been applied for the treatment of the disease. However, these drugs have not shown high efficacy in reducing COVID-19 severity, and even antiviral drugs have not shown to be effective. Researchers thus continue to search for an effective adjuvant therapy with a combination of drugs or vaccines to treat COVID-19 disease. We were motivated to consider melatonin as a defensive agent against SARS-CoV-2 because of its various unique properties. Over 200 scientific publications have shown the significant effects of melatonin in treating diseases, with strong antioxidant, anti-inflammatory, and immunomodulatory effects. Melatonin has a high safety profile, but it needs further clinical trials and experiments for use as a therapeutic agent against the Omicron variant of COVID-19. It might immediately be able to prevent the development of severe symptoms caused by the coronavirus and can reduce the severity of the infection by improving immunity.

[Three Cases of No. 16 Lymph Node Metastasis-Positive Gastric Cancer Successfully Treated with Chemotherapy and Para-Aortic Lymph Node Dissection].

Chemotherapy is standard treatment for Stage Ⅳ advanced gastric cancer(AGC)positive for No. 16 lymph node(LN) metastasis, but the significance of conversion surgery remains unclear. S-1 plus CDDP(SP), primary lesion resection+ para-aortic LN dissection(PAND), and postoperative recurrence-free survival are reported. Case 1: A 70-year-old woman had AGC with para-aortic LN metastases(tub1, HER2 score 3+, cT3N2M1, cStage Ⅳ). Four courses of SP plus trastuzumab were administered, which shrank the primary tumor and metastatic LNs. She underwent distal gastrectomy with D2+PAND (No. 16a2 int-b1 int). Histopathology showed metastasis to No. 16 LN, with Grade 2 histological effect. She underwent adjuvant chemotherapy with S-1 and 4-year recurrence-free follow-up. Case 2: An 80-year-old man with AGC rand para- aortic LN metastases(por, cT3N2M1, cStage Ⅳ)underwent 4 courses of SP, which shrank the primary tumor and metastatic LNs. He underwent total gastrectomy with D2+PAND(No. 16a2 lat)dissection. Histopathology showed no residual tumor cells in LNs. Follow-up for 3 years has shown no recurrence without chemotherapy. Case 3: A 50-year-old woman with epigastric pain and anemia had AGC with para-aortic LN metastases(tub2, cT3N3M1, cStage Ⅳ). She underwent distal gastrectomy with D2+PAND(No. 16a2 int-b1 lat). After 1-year chemotherapy with SP, follow-up for 5 years showed no recurrence. In AGC with para-aortic LN metastases, long-term survival can be expected by combining selective PAND with SP therapy.

Dermal Fibroblasts Internalize Phosphatidylserine-Exposed Secretory Melanosome Clusters and Apoptotic Melanocytes.

Pigmentation in the dermis is known to be caused by melanophages, defined as melanosome-laden macrophages. In this study, we show that dermal fibroblasts also have an ability to uptake melanosomes and apoptotic melanocytes. We have previously demonstrated that normal human melanocytes constantly secrete melanosome clusters from various sites of their dendrites. After adding secreted melanosome clusters collected from the culture medium of melanocytes, time-lapse imaging showed that fibroblasts actively attached to the secreted melanosome clusters and incorporated them. Annexin V staining revealed that phosphatidylserine (PtdSer), which is known as an 'eat-me' signal that triggers the internalization of apoptotic cells by macrophages, is exposed on the surface of secreted melanosome clusters. Dermal fibroblasts were able to uptake secreted melanosome clusters as did macrophages, and those fibroblasts express TIM4, a receptor for PtdSer-mediated endocytosis. Further, co-cultures of fibroblasts and melanocytes demonstrated that dermal fibroblasts internalize PtdSer-exposed apoptotic melanocytes. These results suggest that not only macrophages, but also dermal fibroblasts contribute to the collection of potentially toxic substances in the dermis, such as secreted melanosome clusters and apoptotic melanocytes, that have been occasionally observed to drop down into the dermis from the epidermis.

Critical Hammett Electron-Donating Ability of Substituent Groups for Efficient Water Oxidation Catalysis by Mononuclear Ruthenium Aquo Complexes.

[Ru(Rtpy)(bpy)(H2O)]2+ (1R; bpy = 2,2'-bipyridine, and Rtpy = 2,2':6',2″-terpyridine derivatives) complexes with a variety of 4'-substituent groups on Rtpy were synthesized and characterized to reveal the effects of substituents on their structures, physicochemical properties, and catalytic activities for water oxidation. The geometric structures of 1R are not considerably influenced by the electron-donating ability of the 4'-substituent groups on Rtpy. Similar multistep proton-coupled electron transfer reactions were observed for 1R, and the redox potentials for each oxidation step tended to decrease with an increase in the electron-donating ability of the substituent, which is explained by the increased electron density on the Ru center by electron-donating groups, stabilizing the positive charge that builds up upon oxidation. This is consistent with the red-shift of the absorption bands around 480 nm assigned to the metal-to-ligand charge transfer transition for 1R due to the increased d orbital energy level of the Ru center. The turnover frequency (kO2) of 1R for water oxidation catalysis, however, depended greatly on the Rtpy ligands, varying from 0.05 × 10-2 to 44 × 10-2 s-1 (as the highest kO2 was observed for R = ethoxy) by a factor of 880. A critical electron-donating ability of the 4'-substituent groups with a narrow range of Hammett constants (σp = -0.27 to -0.24) found for the highest kO2 values is valuable for understanding the great difficulty in the search for efficient water oxidation catalysts. On another front, the kO2 values increased with a decrease in the redox potentials of RuIV═O/RuV═O for 1R, indicating that the potential of formation of RuV═O species for 1R is crucial for water oxidation catalysis under the employed conditions.

Identification of Antiglycative Compounds in Japanese Red Water Pepper (Red Leaf Variant of the Persicaria hydropiper Sprout).

Glycation, the nonenzymatic reaction between proteins and excess blood sugar, is implicated in multiple disorders and occurs via the formation and accumulation of advanced glycation end products (AGEs). In our previous studies, we demonstrated that the red-leaf variant of the Persicaria hydropiper sprout (Japanese red water pepper, Benitade) is one of the potent plants that inhibit formation of AGEs. In this study, we aimed to identify antiglycative compounds in Benitade. Benitade extracts were prepared with hot water, then fractionated by using high-performance liquid chromatography (HPLC). The antiglycative efficacy of each fraction was evaluated by measuring the formation of fluorescent AGEs (Ex 370 nm/Em 440 nm). Two fractions, which contained peaks at 26.4 min and 31.8 min, showed potent antiglycative efficacy. When we hydrolyzed these peaks, they shifted to 32.5 and 41.4 min, which are the same retention times as cyanidin and quercetin, respectively. Based on thin-layer chromatography, both compounds contained galactose. Finally, ultrahigh-performance liquid chromatography/quadrupole-time of flight mass spectrometry (UHPLC-QqTOF-MS) analyses were performed to determine the structure of those compounds. Overall, we identified two glycosides, cyanidin 3-O-galactoside (idaein) and quercetin 3-O-galactoside (hyperin), as representative antiglycative compounds in Benitade.

Dual-Functional Surfactant-Templated Strategy for Synthesis of an In Situ N2 -Intercalated Mesoporous WO3 Photoanode for Efficient Visible-Light-Driven Water Oxidation.

N2 -Intercalated crystalline mesoporous tungsten trioxide (WO3 ) was synthesized by a thermal decomposition technique with dodecylamine (DDA) as a surfactant template with a dual role as an N-atom source for N2 intercalation, alongside its conventional structure-directing role (by micelle formation) to induce a mesoporous structure. N2 physisorption analysis showed that the specific surface area (57.3 m2 g-1 ) of WO3 templated with DDA (WO3 -DDA) is 2.3 times higher than that of 24.5 m2 g-1 for WO3 prepared without DDA (WO3 -bulk), due to the mesoporous structure of WO3 -DDA. The Raman and X-ray photoelectron spectra of WO3 -DDA indicated intercalation of N2 into the WO3 lattice above 450 °C. The UV/Vis diffuse-reflectance spectra exhibited a significant shift of the absorption edge by 28 nm, from 459 nm (2.70 eV) to 487 nm (2.54 eV), due to N2 intercalation. This could be explained by the bandgap narrowing of WO3 -DDA by formation of a new intermediate N 2p orbital between the conduction and valance bands of WO3 . A WO3 -DDA-coated indium tin oxide (ITO) electrode calcined at 450 °C generated a photoanodic current under visible-light irradiation below 490 nm due to photoelectrochemical water oxidation, as opposed to below 470 nm for ITO/WO3 -bulk. The incident photon-to-current conversion efficiency (IPCE=24.5 %) at 420 nm and 0.5 V versus Ag/AgCl was higher than that of 2.5 % for ITO/WO3 -bulk by one order of magnitude due to N2 intercalation and the mesoporous structure of WO3 -DDA.

Light Energy Accumulation from Pyrene Derivative to Tris(bipyridine)ruthenium on Clay Surface.

A novel type of energy donor-acceptor system on a clay surface has been prepared. The energy transfer between an energy-donating cationic pyrene derivative (An-Py2+) and an energy-accepting tris(bipyridine)ruthenium complex (Ru2+) on the clay surface was investigated using absorption, emission, and lifetime measurements. An obvious energy transfer was observed, and one Ru2+ molecule quenched the emission from five molecules of An-Py2+ with an emission quenching efficiency of 85% on the clay surface. This suggests that the light energies absorbed by five of the An-Py2+ molecules were accumulated in the one Ru2+ molecule. Near-quantitative emission quenching was observed for stoichiometric amounts of An-Py2+ and Ru2+. The apparent quenching rate constant is approximately 1017 L mol-1 s-1, and thus the quenching rate constant is 107-108 times higher than the diffusion rate constant in a homogeneous solution.

Mechanistic Insight into Reversible Core Structural Changes of Dinuclear µ-Hydroxoruthenium(II) Complexes with a 2,8-Di-2-pyridyl-1,9,10-anthyridine Backbone Prior to Water Oxidation Catalysis.

proximal,proximal-(p,p)-[RuII2(tpy)2LXY]n+ (tpy = 2,2';6',2″-terpyridine, L = 5-phenyl-2,8-di-2-pyridyl-1,9,10-anthyridine, and X and Y = other coordination sites) yields the structurally and functionally unusual RuII(µ-OH)RuII core, which is capable of catalyzing water oxidation with key water insertion to the core (Inorg. Chem. 2015, 54, 7627). Herein, we studied a sequence of bridging-ligand substitution among p,p-[Ru2(tpy)2L(µ-Cl)]3+ (Ru2(µ-Cl)), p,p-[Ru2(tpy)2L(µ-OH)]3+ (Ru2(µ-OH)), p,p-[Ru2(tpy)2L(OH)(OH2)]3+ (Ru2(OH)(OH2)), and p,p-[Ru2(tpy)2L(OH)2]2+ (Ru2(OH)2) in aqueous solution. Ru2(µ-Cl) converted slowly (10-4 s-1) to Ru2(µ-OH), and further Ru2(µ-OH) converted very slowly (10-6 s-1) to Ru2(OH)(OH2) by the insertion of water to reach equilibrium at pH 8.5-12.3. On the basis of density functional theory (DFT) calculations, Ru2(OH)(OH2) was predicted to be thermodynamically stable by 13.3 kJ mol-1 in water compared to Ru2(µ-OH) because of the specially stabilized core structure by multiple hydrogen-bonding interactions involving aquo, hydroxo, and L backbone ligands. The observed rate from Ru2(µ-OH) to Ru2(OH)2 by the insertion of an OH- ion increased linearly with an increase in the OH- concentration from 10 to 100 mM. The water insertion to the core is very slow (∼10-6 s-1) in aqueous solution at pH 8.5-12.3, whereas the insertion of OH- ions is accelerated (10-5-10-4 s-1) above pH 13.4 by 2 orders of magnitude. The kinetic data including activation parameters suggest that the associative mechanism for the insertion of water to the RuII(µ-OH)RuII core of Ru2(µ-OH) at pH 8.5-12.3 alters the interchange mechanism for the insertion of an OH- ion to the core above pH 13.4 because of relatively stronger nucleophilic attack of OH- ions. The hypothesized p,p-[Ru2(tpy)2L(µ-OH2)]4+ and p,p-[Ru2(tpy)2L(OH2)2]4+ formed by protonation from Ru2(µ-OH) and Ru2(OH)(OH2) were predicted to be unstable by 71.3 and 112.4 kJ mol-1 compared to Ru2(µ-OH) and Ru2(OH)(OH2), respectively. The reverse reactions of Ru2(µ-OH), Ru2(OH)(OH2), and Ru2(OH)2 to Ru2(µ-Cl) below pH 5 could be caused by lowering the core charge by protonation of the µ-OH- or OH- ligand.

Visible-Light-Induced Morphological Changes of Giant Vesicles by Photoisomerization of a Ruthenium Aqua Complex.

Visible- and red-light responsive vesicles were prepared by incorporating a ruthenium aqua complex having two alkyl chains on tridentate and asymmetrical bidentate ligands (proximal-2: [Ru(C10 tpy)(C10 pyqu)OH2 ](2+) , C10 tpy=4'-decyloxy-2,2';6',2"-terpyridine, C10 pyqu=2-[2'-(6'-decyloxy)-pyridyl]quinoline). The ruthenium complex of proximal-2 with closed alkyl chain geometry and a cylinder-like molecular shape exhibited photoisomerization to distal-2 with an open alkyl chain geometry and a cone-like shape, both in an aqueous solution and in vesicle dispersions. We observed that light irradiation of giant vesicles containing proximal-2 induced diverse morphological changes.

Remarkable stimulation of emission quenching on a clay surface.

Tetra-cationic pyrene derivative (Py(4+)) and tris(bipyridine)ruthenium(II) (Ru(2+)) were hybridized onto the surface of a synthesized clay. We observed the remarkable stimulation of excited Py(4+) emission quenching on the clay surface, with a very large apparent quenching rate constant (kq = 7.4 ± 0.7 × 10(15) L mol(-1) s(-1)).

Intercrystal self-assembly for the design of high-quality nickel molybdate nanocrystals.

Nanowire of nickel molybdate hydrate, being recognized as an emerging supercapacitor material, was synthesized from the intercrystal self-assembly process (commonly referred to as oriented aggregation or attachment). The detailed lattice image of a NiMoO4·0.75H2O nanowire and the intermediate nanostructure before reaching the interplanar binding were successfully captured by means of high-resolution transmission and scanning electron microscopies. NiMoO4·0.75H2O possessed highly crystalline surface and internal nanostructures.

New Series of Dinuclear Ruthenium(II) Complexes Synthesized Using Photoisomerization for Efficient Water Oxidation Catalysis.

A new series of proximal,proximal-[Ru2(tpy)2(L)XY](n+) (p,p-Ru2XY, tpy = 2,2':6',2″-terpyridine, L = 5-phenyl-2,8-di(2-pyridyl)-1,9,10-anthyridine, X and Y = other coordination sites) were synthesized using photoisomerization of a mononuclear complex. The p,p-Ru2XY complexes undergo unusual reversible bridge-exchange reactions to generate p,p-Ru2(µ-Cl), p,p-Ru2(µ-OH), and p,p-Ru2(OH)(OH2) with µ-Cl, µ-OH, as well as hydroxo and aquo ligands at X and Y sites of p,p-Ru2XY, respectively. The geometric and electronic structures of these complexes were characterized based on UV-vis and (1)H NMR spectra, X-ray crystallography, and density functional theory (DFT) calculations. (1)H NMR data showed C2 symmetry of p,p-Ru2(OH)(OH2) with the distorted L chelate and nonequivalence of two tpy ligands, in contrast to the C2v symmetry of p,p-Ru2(µ-Cl) and p,p-Ru2(µ-OH). However, irrespective of the lower symmetry, p,p-Ru2(OH)(OH2) is predominantly formed in neutral and weakly basic conditions due to the specially stabilized core structure by multiple hydrogen-bond interactions among aquo, hydroxo, and backbone L ligands. The electrochemical data suggested that p,p-Ru2(OH)(OH2) (Ru(II)-OH:Ru(II)-OH2) is oxidized to the Ru(III)-OH:Ru(III)-OH state at 0.64 V vs saturated calomel electrode (SCE) and further to Ru(IV)═O:Ru(IV)-OH at 0.79 V by successive 1-proton-coupled 2-electron processes at pH 7.0. The cyclic voltammogram data exhibited that the p,p-Ru2(OH)(OH2) complex works more efficiently for electrocatalytic water oxidation, compared with a similar mononuclear complex distal-[Ru(tpy)(L)OH2](2+) (d-RuOH2) and p,p-Ru2(µ-Cl) and p,p-Ru2(µ-OH), showing that the p,p-Ru2 core structure with aquo and hydroxo ligands is important for efficient electrocatalytic water oxidation. Bulk electrolysis of the p,p-Ru2(OH)(OH2) solution corroborated the electrocatalytic cycle involving the Ru(III)-OH:Ru(III)-OH state species as a resting state. The mechanistic insight into O-O bond formation for O2 production was provided by the isotope effect on electrocatalytic water oxidation by p,p-Ru2(OH)(OH2) and d-RuOH2 in H2O and D2O media.

Sustainable synthesis of niobia thin films with open mesopore channels.

The current approaches to electrochemically synthesizing valve metal-derived nanochannel films with longitudinal nanospaces aligned at a right angle to planar substrates rely on highly toxic fluoride compounds and require severe reaction conditions. Herein, we report on a fluoride-free, room-temperature electrochemical synthesis of a genuine mesoporous niobia thin film from the parent metal. The electrochemical reaction is driven by only a 1 V bias with respect to a Pt counter electrode in an aqueous solution. The solution contained an inexpensive, less toxic potassium hydroxide, and the reaction produced favorable byproducts, namely, recyclable K8Nb6O19 and H2.

Assessing associated factors for failure of nonoperative management in pediatric blunt liver and spleen injuries: a secondary analysis of the SHIPPs study.

PURPOSE: The purpose of this study was to describe the characteristics of pediatric patients who underwent nonoperative management (NOM) for blunt splenic and hepatic injuries and to explore factors associated with NOM failure. METHODS: This was a secondary analysis of a multicenter cohort study of pediatric patients with blunt liver and spleen injuries in Japan. Participants included pediatric trauma patients aged 16 years or younger between 2008 and 2019 with NOM, which was defined as no surgery provided within 6 h of hospital arrival. NOM failure, defined as abdominal surgery performed after 6 h of hospital arrival, was the primary outcome. Descriptive statistics were provided and exploratory analysis to assess the associations with outcome using logistic regression. RESULTS: During the study period, 1339 met our eligibility criteria. The median age was 9 years, with a majority being male. The median Injury Severity Score (ISS) was 10. About 14.0% required transfusion within 24 h, and 22.3% underwent interventional radiology procedures. NOM failure occurred in 1.0% of patients and the in-hospital mortality was 0.7%. Factors associated with NOM failure included age, positive focused assessment with sonography for trauma (FAST), contrast extravasation on computed tomography (CT), severe liver injury, concomitant pancreas injury, concomitant gastrointestinal injury, concomitant mesenteric injury, and ISS. CONCLUSIONS: In our study, NOM failure were rare. Older age, positive FAST, contrast extravasation on CT, severe liver injury, concomitant pancreas injury, concomitant gastrointestinal injury, concomitant mesenteric injury, and higher ISS were suggested as possible risk factors for NOM failure.

Association of Contrast Extravasation Grade With Massive Transfusion in Pediatric Blunt Liver and Spleen Injuries: A Multicenter Retrospective Cohort Study.

BACKGROUND: This study aimed to assess whether the grade of contrast extravasation (CE) on CT scans was associated with massive transfusion (MT) requirements in pediatric blunt liver and/or spleen injuries (BLSI). METHODS: This multicenter retrospective cohort study included pediatric patients (≤16 years old) who sustained BLSI between 2008 and 2019. MT was defined as transfusion of all blood products ≥40 mL/kg within the first 24 h of admission. Associations between CE and MT requirements were assessed using multivariate logistic regression analysis with cluster-adjusted robust standard errors to calculate the adjusted odds ratio (AOR). RESULTS: A total of 1407 children (median age: 9 years) from 83 institutions were included in the analysis. Overall, 199 patients (14 %) received MT. CT on admission revealed that 54 patients (3.8 %) had CE within the subcapsular hematoma, 100 patients (7.1 %) had intraparenchymal CE, and 86 patients (6.1 %) had CE into the peritoneal cavity among the overall cohort. Multivariate analysis, adjusted for age, sex, age-adjusted shock index, injury severity, and laboratory and imaging factors, showed that intraparenchymal CE and CE into the peritoneal cavity were significantly associated with the need for MT (AOR: 2.50; 95 % CI, 1.50-4.16 and AOR: 4.98; 95 % CI, 2.75-9.02, respectively both p < 0.001). The latter significant association persisted in the subgroup of patients with spleen and liver injuries. CONCLUSION: Active CE into the free peritoneal cavity on admission CT was independently associated with a greater probability of receiving MT in pediatric BLSI. The CE grade may help clinicians plan blood transfusion strategies. LEVEL OF EVIDENCE: Level 4; Therapeutic/Care management.