An Aqueous Redox Flow Battery Using CO2 as an Active Material with a Homogeneous Ir Catalyst.

For the application of CO2 as an energy storage material, a H2 storage system has been proposed based on the interconversion of CO2 and formic acid (or formate). However, energy losses are inevitable in the conversion of electrical energy to H2 as chemical energy (≈70 % electrical efficiency) and H2 to electrical energy (≈40 % electrical efficiency). To overcome these significant energy losses, we developed a system based on the interconversion of CO2 and formate for the direct storage and generation of electricity. In this paper, we report an aqueous redox flow battery system using homogeneous Ir catalysts with CO2 -formate redox pair. The system exhibited a maximum discharge capacity of 10.5 mAh (1.5 Ah L-1 ), capacity decay of 0.2 % per cycle, and total turnover number of 2550 after 50 cycles. During charging-discharging, in situ fluorescence X-ray absorption fine structure spectroscopy based on an online setup indicated that the active species was in a high valence state of IrIV .

A case of necrotizing fasciitis caused by Bifidobacterium breve.

Background: Bifidobacterium breve is an obligate anaerobic gram-positive bacillus mainly found in the gastrointestinal tract of human infants. Few cases of necrotizing fasciitis caused by B. breve have been reported. Case presentation: A 42-year-old Japanese man with type 2 diabetes mellitus, obesity, cellulitis of the back, and subcutaneous abscess of the right inguinal region presented with rapidly developing erythema, swelling and severe pain in the right inguinal region. Computed tomography showed widespread gas in the right leg region. Cultures of blood and a swab of the wound abscess grew gram-positive bacilli. Mass spectrography and 16 S rDNA analysis confirmed the gram-positive bacilli as B. breve. The patient recovered following extensive debridement and antibacterial therapy. Conclusion: Unidentified necrotizing fasciitis can be caused by B. breve, especially in compromised hosts.

Recent Progress in Homogeneous Catalytic Dehydrogenation of Formic Acid.

Recently, there has been a strong demand for technologies that use hydrogen as an energy carrier, instead of fossil fuels. Hence, new and effective hydrogen storage technologies are attracting increasing attention. Formic acid (FA) is considered an effective liquid chemical for hydrogen storage because it is easier to handle than solid or gaseous materials. This review presents recent advances in research into the development of homogeneous catalysts, primarily focusing on hydrogen generation by FA dehydrogenation. Notably, this review will aid in the development of useful catalysts, thereby accelerating the transition to a hydrogen-based society.

Altered consciousness with transient abnormal signals in the hippocampus: A case report.

Hippocampal infarction is relatively rare. Many different diseases can mimic hippocampal infarction including transient global amnesia, Alzheimer's disease, epilepsy, encephalitis, and encephalopathies. An 89-year-old man was transported to our hospital for altered consciousness. Diffusion-weighted magnetic resonance imaging revealed slightly intense signals in the hippocampus with a mildly decreased apparent diffusion coefficient. Serial magnetic resonance imaging revealed features of hippocampal infarction. Symptoms and cognitive function gradually improved with rehabilitation, and he was transferred to a rehabilitation facility on Hospital Day 38. Hippocampal infarction is rare in patients with altered mental status, but should be considered when magnetic resonance imaging shows findings suggestive of this condition. Other differential diseases should be ruled out by serial magnetic resonance imaging and observation of the clinical course.

Catalytic Hydrogenation of CO2 to Methanol Using Multinuclear Iridium Complexes in a Gas-Solid Phase Reaction.

We report a novel approach toward the catalytic hydrogenation of CO2 to methanol performed in the gas-solid phase using multinuclear iridium complexes at low temperature (30-80 °C). Although homogeneous CO2 hydrogenation in water catalyzed by amide-based iridium catalysts provided only a negligible amount of methanol, the combination of a multinuclear catalyst and gas-solid phase reaction conditions led to the effective production of methanol from CO2. The catalytic activities of the multinuclear catalyst were dependent on the relative configuration of each active species. Conveniently, methanol obtained from the gas phase could be easily isolated from the catalyst without contamination with CO, CH4, or formic acid (FA). The catalyst can be recycled in a batchwise manner via gas release and filling. A final turnover number of 113 was obtained upon reusing the catalyst at 60 °C and 4 MPa of H2/CO2 (3:1). The high reactivity of this system has been attributed to hydride complex formation upon exposure to H2 gas, suppression of the liberation of FA under gas-solid phase reaction conditions, and intramolecular multiple hydride transfer to CO2 by the multinuclear catalyst.

Tachyarrhythmia improved by management of low back pain in a patient with delayed diagnosis of infective spondylodiscitis: A case report.

A 77-year-old man presented to the emergency room with a 1-month history of persistent low back pain with the absence of vital sign abnormalities. On several previous orthopedic surgery clinic visits, pathological back pain had not been considered and pain killers had been prescribed because he had low back pain due to lumbar spinal canal stenosis. He was admitted to the intensive care unit for infectious spondylodiscitis and infective endocarditis with disseminated abscess caused by methicillin-resistant Staphylococcus aureus. Shock refractory tachyarrhythmia could not be managed with antiarrhythmic agent in the intensive care unit. Intractable low back pain and persistent tachyarrhythmia were adequately managed by pain control with fentanyl in the intensive care unit. Infectious spondylodiscitis and infective endocarditis were effectively managed with anti-methicillin-resistant Staphylococcus aureus drugs, initially in rotational usage, but the patient died of extended-spectrum beta-lactamase-producing Escherichia coli pneumonia on day 50 of hospitalization. Infectious spondylodiscitis should have been considered for persistent low back pain with hemodialysis, fever, and a history of device implantation. Pain management may be necessary for persistent tachycardia that proves unresponsive to usual antiarrhythmic medications.

Ligand Effect on the Stability of Water-Soluble Iridium Catalysts for High-Pressure Hydrogen Gas Production by Dehydrogenation of Formic Acid.

Aiming to develop a highly effective and durable catalyst for high-pressure H2 production from dehydrogenation of formic acid (DFA), the ligand effect on the catalytic activity and stability of Cp*Ir (Cp*:pentamethylcyclopentadienyl anion) complexes were investigated using 5 different kinds of N,N'-bidentate ligands (bipyridine, biimidazoline, pyridyl-imidazoline, pyridyl-pyrazole and picolinamide). The Ir complex with biimidazoline ligand exhibited the highest catalytic activity, but deactivation occurred readily at high pressure. The pyridine moiety in the ligand can enhance the stability of Ir complex catalysts for the high-pressure reaction. The Ir complex catalyst containing pyridyl-imidazoline ligand showed the high activity and best stability under the high-pressure conditions.

Picolinamide-Based Iridium Catalysts for Dehydrogenation of Formic Acid in Water: Effect of Amide N Substituent on Activity and Stability.

To develop highly efficient catalysts for dehydrogenation of formic acid in water, we investigated several Cp*Ir catalysts with various amide ligands. The catalyst with an N-phenylpicolinamide ligand exhibited a TOF of 118 000 h-1 at 60 °C. A constant rate (TOF>35 000 h-1 ) was maintained for six hours, and a TON of 1 000 000 was achieved at 50 °C.

Efficient Hydrogen Storage and Production Using a Catalyst with an Imidazoline-Based, Proton-Responsive Ligand.

A series of new imidazoline-based iridium complexes has been developed for hydrogenation of CO2 and dehydrogenation of formic acid. One of the proton-responsive complexes bearing two -OH groups at ortho and para positions on a coordinating pyridine ring (3 b) can catalyze efficiently the chemical fixation of CO2 and release H2 under mild conditions in aqueous media without using organic additives/solvents. Notably, hydrogenation of CO2 can be efficiently carried out under CO2 and H2 at atmospheric pressure in basic water by 3 b, achieving a turnover frequency of 106 h-1 and a turnover number of 7280 at 25 °C, which are higher than ever reported. Moreover, highly efficient CO-free hydrogen production from formic acid in aqueous solution employing the same catalyst under mild conditions has been achieved, thus providing a promising potential H2 -storage system in water.

CO2 Hydrogenation Catalyzed by Iridium Complexes with a Proton-Responsive Ligand.

The catalytic cycle for the production of formic acid by CO2 hydrogenation and the reverse reaction have received renewed attention because they are viewed as offering a viable scheme for hydrogen storage and release. In this Forum Article, CO2 hydrogenation catalyzed by iridium complexes bearing sophisticated N^N-bidentate ligands is reported. We describe how a ligand containing hydroxy groups as proton-responsive substituents enhances the catalytic performance by an electronic effect of the oxyanions and a pendent-base effect through secondary coordination sphere interactions. In particular, [(Cp*IrCl)2(TH2BPM)]Cl2 (Cp* = pentamethylcyclopentadienyl; TH2BPM = 4,4',6,6'-tetrahydroxy-2,2'-bipyrimidine) enormously promotes the catalytic hydrogenation of CO2 in basic water by these synergistic effects under atmospheric pressure and at room temperature. Additionally, newly designed complexes with azole-type ligands were applied to CO2 hydrogenation. The catalytic efficiencies of the azole-type complexes were much higher than that of the unsubstituted bipyridine complex [Cp*Ir(bpy)(OH2)]SO4. Furthermore, the introduction of one or more hydroxy groups into ligands such as 2-pyrazolyl-6-hydroxypyridine, 2-pyrazolyl-4,6-dihydroxypyrimidine, and 4-pyrazolyl-2,6-dihydroxypyrimidine enhanced the catalytic activity. It is clear that the incorporation of additional electron-donating functionalities into proton-responsive azole-type ligands is effective for promoting further enhanced hydrogenation of CO2.