Towards Implantable Bio-Supercapacitors: Pseudocapacitance of Ruthenium Oxide Nanoparticles and Nanosheets in Acids, Buffered Solutions, and Bioelectrolytes

Metal oxides, in particular ruthenium-based oxides, are promising electrode materials for aqueous pseudocapacitors. Strong acids or bases are favored over neutral electrolytes owing to the higher capacitance. Here we explore the pseudocapacitive behavior of ruthenium oxide nanoparticles and nanosheets in near neutral pH as an environmentally benign electrolyte. The pseudocapacitive charge storage in poorly-crystalline hydrous RuO2 nanoparticles, and highly-crystalline RuO2 nanosheets were investigated in acetic acid-lithium acetate (AcOH-AcOLi) buffered solutions. It is shown that capacitance values as high as 1,038 F g(-1) can be achieved in AcOH-AcOLi buffered solutions with RuO2 nanosheets, which is 44% higher than the benchmark RuO2 nH(2)O in H2SO4 electrolyte (720 F g(-1)). Furthermore, comparable performance was obtained in phosphate buffered saline and fetal bovine serum. The mechanism of the pseudocapacitive properties is discussed based on the difference in the surface redox behavior of different RuO2 nanomaterials in acid, neutral, buffered solutions, and in weak acid. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY. 162(5):A5001-A5006 (2015)journal articl

Development of a 4.2 V aqueous hybrid electrochemical capacitor based on MnO2 positive and protected Li negative electrodes

An aqueous hybrid electrochemical capacitor consisting of a capacitive manganese oxide (MnO2) positive electrode and a water-stable, protected Li negative electrode in near-neutral aqueous electrolyte (1.0 M Li2SO4, pH = 5.5) is demonstrated. Galvanostatic charge/discharge cycling tests were conducted with pouched cells, offering a cell voltage of 4.2 V with maximum specific energy of 753 W h kg(-1) based on the positive electrode. The combination of a pseudocapacitive MnO2 positive and a Li negative electrode offers high specific charge and cell voltage, resulting in an aqueous hybrid electrochemical capacitor having exceptionally high specific energy.ArticleJOURNAL OF POWER SOURCES. 241:572-577 (2013)journal articl

Synthesis of ordered mesoporous ruthenium by lyotropic liquid crystals and its electrochemical conversion to mesoporous ruthenium oxide with high surface area

In ordered to prepare high capacitance pseudo-capacitive oxides, it is important to design nanostructures with appreciable mesopores. Supramolecular templating has become a popular method to synthesize ordered mesoporous metals; however, the application of the same technique to synthesis of high surface area oxides is more demanding. We present here, the synthesis of ordered mesoporous ruthenium metal by lyotropic liquid crystal templating and its electrochemical conversion to ordered mesoporous ruthenium oxide by a simple, room temperature procedure. The bulk, unsupported metallic ordered mesoporous ruthenium exhibits high surface area of 110 m(2) g(-1), which is comparable to typical supported Ru nanoparticles. The oxide analogue gives a high specific capacitance of 376 Fg(-1), owing to the porous structure. These results demonstrate a possible facile and generic process to synthesize oxides with ordered nanostructures by utilization of the various phases that can be obtained with lyotropic liquid crystalline templates such as cubic, hexagonal, lamellar, etc.ArticleJOURNAL OF POWER SOURCES. 204:244-248 (2012)journal articl

In-hospital extracorporeal cardiopulmonary resuscitation for patients with out-of-hospital cardiac arrest: an analysis by time-dependent propensity score matching using a nationwide database in Japan

院外心停止患者における膜型人工肺を活用した蘇生 --膜型人工肺を活用した蘇生と生存率向上との関連--. 京都大学プレスリリース. 2023-11-21.BACKGROUND: Extracorporeal cardiopulmonary resuscitation (ECPR) has been proposed as a rescue therapy for patients with refractory cardiac arrest. This study aimed to evaluate the association between ECPR and clinical outcomes among patients with out-of-hospital cardiac arrest (OHCA) using risk-set matching with a time-dependent propensity score. METHODS: This was a secondary analysis of the JAAM-OHCA registry data, a nationwide multicenter prospective study of patients with OHCA, from June 2014 and December 2019, that included adults (≥ 18 years) with OHCA. Initial cardiac rhythm was classified as shockable and non-shockable. Patients who received ECPR were sequentially matched with the control, within the same time (minutes) based on time-dependent propensity scores calculated from potential confounders. The odds ratios with 95% confidence intervals (CI) for 30-day survival and 30-day favorable neurological outcomes were estimated for ECPR cases using a conditional logistic model. RESULTS: Of 57, 754 patients in the JAAM-OHCA registry, we selected 1826 patients with an initial shockable rhythm (treated with ECPR, n = 913 and control, n = 913) and a cohort of 740 patients with an initial non-shockable rhythm (treated with ECPR, n = 370 and control, n = 370). In these matched cohorts, the odds ratio for 30-day survival in the ECPR group was 1.76 [95%CI 1.38-2.25] for shockable rhythm and 5.37 [95%CI 2.53-11.43] for non-shockable rhythm, compared to controls. For favorable neurological outcomes, the odds ratio in the ECPR group was 1.11 [95%CI 0.82-1.49] for shockable rhythm and 4.25 [95%CI 1.43-12.63] for non-shockable rhythm, compared to controls. CONCLUSION: ECPR was associated with increased 30-day survival in patients with OHCA with initial shockable and even non-shockable rhythms. Further research is warranted to investigate the reproducibility of the results and who is the best candidate for ECPR

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

Improved Water-stable Protected Anodes with Low Resistance for Aqueous Energy Storage Devices

Multi-component anodes, fabricated by assembling lithium metal or pre-lithiated graphite negative electrode, a lithium-ion conducting solid electrolyte with water stability and a polymer or gel electrolyte in between the negative electrode and solid electrolyte, are promising as water-stable protected anodes for next-generation batteries and hybrid capacitors. By applying the protected anode to hybrid capacitors, operating voltage of 4 V can be achieved in aqueous electrolytes. However, the protected anode suffers from large resistance due to its multi-component structure, leading to insufficient power density and energy conversion efficiency. Here we analyze various protected anodes by using electrochemical impedance spectroscopy (EIS) to evaluate the bottleneck components in order to reduce the overall resistance. Protected anodes with different polymers or gel membranes, lithium salts and ionic liquid additives, negative electrode materials, binders, and solid electrolytes, were fabricated and the impedance components were analyzed. The resistance of the protected anode was successfully reduced by selecting proper materials

Synthesis of electro-deposited ordered mesoporous RuOx using lyotropic liquid crystal and application toward micro-supercapacitors

Synthesis of ordered mesoporous RuOx electrodes was conducted by electro-deposition using a lyotropic liquid crystal template method with Ti substrates and subsequent electro-oxidation. The obtained ordered mesoporous Ru metal was characterized by XRD, TEM and electrochemical measurements in 0.5 M H2SO4. After electro-oxidation by potential cycling, the ordered mesoporous RuOx afforded specific capacitance of similar to 400 F (g-Ru)(-1). A micro-supercapacitor with ordered mesoporous RuOx was fabricated by controlled electro-deposition of ordered mesoporous RuOx on an inter-digitated array electrode (IDA; 10 mu m electrode width, 5 mu m gap and 65 x 2 electrodes). This micro-supercapacitor exhibited good capacitive property with maximum specific capacitance of 12.6 mF cm(-2) and specific energy of 12.5 Wh (kg-Ru)(-1) based on the mass of the deposited material