A single-ion conducting covalent organic framework for aqueous rechargeable Zn-ion batteries

Despite their potential as promising alternatives to current state-of-the-art lithium-ion batteries, aqueous rechargeable Zn-ion batteries are still far away from practical applications. Here, we present a new class of single-ion conducting electrolytes based on a zinc sulfonated covalent organic framework (TpPa-SO3Zn0.5) to address this challenging issue. TpPa-SO3Zn0.5 is synthesised to exhibit single Zn2+ conduction behaviour via its delocalised sulfonates that are covalently tethered to directional pores and achieve structural robustness by its beta-ketoenamine linkages. Driven by these structural and physicochemical features, TpPa-SO3Zn0.5 improves the redox reliability of the Zn metal anode and acts as an ionomeric buffer layer for stabilising the MnO2 cathode. Such improvements in the TpPa-SO3Zn0.5-electrode interfaces, along with the ion transport phenomena, enable aqueous Zn-MnO2 batteries to exhibit long-term cyclability, demonstrating the viability of COF-mediated electrolytes for Zn-ion batteries

Reversibly controlled ternary polar states and ferroelectric bias promoted by boosting square???tensile???strain

Interaction between dipoles often emerges intriguing physical phenomena, such as exchange bias in the magnetic heterostructures and magnetoelectric effect in multiferroics, which lead to advances in multifunctional heterostructures. However, the defect-dipole tends to be considered the undesired to deteriorate the electronic functionality. Here, we report deterministic switching between the ferroelectric and the pinched states by exploiting a new substrate of cubic perovskite, BaZrO3, which boosts square-tensile-strain to BaTiO3 and promotes four-variants in-plane spontaneous polarization with oxygen vacancy creation. First-principles calculations propose a complex of an oxygen vacancy and two Ti3+ ions coins a charge-neutral defect-dipole. Cooperative control of the defect-dipole and the spontaneous polarization reveals ternary in-plane polar states characterized by biased/pinched hysteresis loops. Furthermore, we experimentally demonstrate that three electrically controlled polar-ordering states lead to switchable and non-volatile dielectric states for application of non-destructive electro-dielectric memory. This discovery opens a new route to develop functional materials via manipulating defect-dipoles and offers a novel platform to advance heteroepitaxy beyond the prevalent perovskite substrates

Novel Deperming Protocols to Reduce Demagnetizing Time and Improve the Performance for the Magnetic Silence of Warships

Magnetic silence of warships is necessary to prevent damage caused by the magnetic mines detecting the magnetic field of the warship. Anhysteretic and Deperm-ME protocols are used to reduce permanent magnetization among magnetic signals. However, they have some disadvantages. Therefore, this paper proposes an effective deperming protocol that is easily controlled and reduces the demagnetization time. A protocol composed of two Anhysteretic protocols is presented using the Preisach model to easily manage and ensure excellent performance. Each stage has its own advantages by considering the Preisach density distribution. In Stage 1, the existing magnetic history is erased, and the demagnetization time is reduced. In Stage 2, the demagnetization performance is improved. The effectiveness of the protocol was verified via simulations using the Preisach model and experiments using a specimen. When the proposed protocol was applied, the results were excellent when applying Anhysteretic and Deperm-ME. In addition, even if the number of magnetic fields was reduced by 4 and 8 in the proposed protocol, the demagnetization result was maintained. Therefore, if the proposed protocol is applied, excellent demagnetization results can be obtained and the time required to perform demagnetization can be reduced, thereby improving the operational capability of the warship

Effects of Electro-Magnetic Properties of Obstacles in Magnetic Resonant Wireless Power Transfer

Magnetic resonant wireless power transmission (MRWPT) is a method of transmitting power over a long distance at a specific frequency. Because this system uses an alternating magnetic field, if an object with electrical/magnetic properties is placed between the transmit and receive coils, this will have a significant impact on the power transfer. In this paper, the effect of an obstacle located between two coils on the resonance frequency and transmission power is analyzed. A wireless power transmission system with a resonant frequency of 20 kHz was designed, and ferrite, aluminum, and carbon steel were selected as obstacles with permeability or conductivity. After simulating the system with finite element analysis (FEA) with these obstacles, the results were verified through actual experiments. The results show that the permeability of the obstacle decreases the resonant frequency, and the conductivity increases the resonant frequency and greatly reduces the output power. In addition, part of reduced output could be recovered by adjusting the frequency

DFT Study for Oxygen Reduction and Oxygen Evolution Reactions in Pyrochlore Oxides as Bi-functional Electrocatalysts

In this study, we studied about the oxygen reduction and oxygen evolution reactions in pyrochlore oxides to investigate the capability as bi-functional electrocatalysts. Initially, the most stable surface terminations were determined by relaxed surface energy calculations. From the most stable terminations including (100), (110), and (111) directions, the reaction intermediates (e.g. OOH*, O*, and OH*) were calculated to investigate the free energy diagrams for oxygen reduction and oxygen evolution reactions (ORR/OER). The results showed that the overpotentials for both reactions were decreased as the –OH coverage increased in alkaline environment. Also, the (110) surface was the most favorable among the surfaces. It was also found that the rubidium site was favorable for ORR whereas the bismuth site was favorable for OER

First-principles Study of Bi-functional Electrocatalytic Activity on Bi2Ru2O7 Pyrochlore Oxide

Among the various electrochemical conversion and storage systems, rechargeable Zn-air batteries have been considered as a promising candidate for future electric devices due to their high specific energy density. To improve the sluggish rate of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which has been pointed out as a critical limitation of Zn-air batteries, pyrochlore oxides (A<sub>2</sub>B<sub>2</sub>O<sub>7</sub>) can be used as a highly efficient bi-functional electrocatalyst because of high charge transfer activity during ORR and OER. However, catalytic origin of them has not been fully explored due to complexities in structure and reaction mechanism. In this work, we investigated the reaction mechanisms for ORR and OER particularly in bismuth ruthenate pyrochlore oxide (Bi<sub>2</sub>Ru<sub>2</sub>O<sub>7</sub>) via density functional theory (DFT) calculation. Initially, we determined the energetically stable surface terminations for each low-index surface (i.e., (100), (110), and (111)). Next, we calculated the adsorption free energies of intermediates for oxygen-involving electrochemical reaction (i.e., OOH<sup>*</sup>, O<sup>*</sup>, and OH<sup>*</sup>). Finally, we constructed a 2D activity map of theoretical overpotentials (<i>??</i>) based on the adsorption free energies, which was used as a descriptor for bi-functional catalytic activity. Interestingly, the Bi and Ru sites were clearly separated in the activity map, induced by differences of binding strengths of reaction intermediates. The active sites with the minimum <i>??</i> were identified to be Bi site for ORR, and Ru site for OER, respectively. Based on the results, we theoretically demonstrated that the Bi<sub>2</sub>Ru<sub>2</sub>O<sub>7</sub> pyrochlore oxide is the excellent bi-functional electrocatalyst, which intrinsically contains different active sites separately working for ORR and OER, due to the distinct binding characteristics by each metal species

Post-induction hypotension with remimazolam versus propofol in patients routinely administered angiotensin axis blockades: a randomized control trial

Abstract Background Certain routine medication could result in post-induction hypotension (PIH), such as angiotensin axis blockades, which are frequently administered as a first-line therapy against hypertension. Remimazolam is reportedly associated with lesser intraoperative hypotension than propofol. This study compared the overall incidence of PIH following remimazolam or propofol administration in patients managed by angiotensin axis blockades. Methods This single-blind, parallel-group, randomized control trial was conducted in a tertiary university hospital in South Korea. Patients undergoing surgery with general anesthesia were considered for enrollment if the inclusion criteria were met: administration of an angiotensin converting enzyme inhibitor or angiotensin receptor blocker, 19 to 65 years old, American Society of Anesthesiologists physical status classification ≤ III, and no involvement in other clinical trials. The primary outcome was the overall incidence of PIH, defined as a mean blood pressure (MBP) < 65 mmHg or decrease by ≥ 30% of the baseline MBP. The time points of measurement were baseline, just before the initial intubation attempt, and 1, 5, 10, and 15 min following intubation. The heart rate, systolic and diastolic blood pressures, and bispectral index were also recorded. Groups P and R included patients administered propofol and remimazolam, respectively, as an induction agent. Results A total of 81 patients were analyzed, of the 82 randomized patients. PIH was less frequent in group R than group P (62.5% versus 82.9%; t value 4.27, P = 0.04, adjusted odds ratio = 0.32 [95% confidence interval 0.10–0.99]). The decrease in the MBP from baseline was 9.6 mmHg lesser in group R than in group P before the initial intubation attempt (95% confidence interval 3.3–15.9). A similar trend was observed for systolic and diastolic blood pressures. No severe adverse events were observed in either group. Conclusion Remimazolam results in less frequent PIH than propofol in patients undergoing routine administration of angiotensin axis blockades. Trial registration This trial was retrospectively registered on Clinical Research Information Service (CRIS), Republic of Korea (KCT0007488). Registration date: 30/06/2022