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Scientific Reports Jun 2022We investigate the impact of the DC current-induced Ampère-Oersted field on the dynamics of a vortex based spin-torque nano-oscillator. In this study we compare...
We investigate the impact of the DC current-induced Ampère-Oersted field on the dynamics of a vortex based spin-torque nano-oscillator. In this study we compare micromagnetic simulations performed using mumax[Formula: see text] and our analytical model based on the Thiele equation approach. The latter is improved by adding two important corrections to the Thiele equation approach. The first is related to the magneto-static contribution and depends on the aspect ratio of the magnetic dot. The second is a full analytical description of the Ampère-Oersted field contribution. The model describes quantitatively the simulation results in the resonant regime as well as the impact of the Ampère-Oersted field. Depending on the relative orientation between the vortex in-plane curling magnetisation (chirality) and the Ampère-Oersted field a strong splitting phenomenon appears in the fundamental properties (frequency and vortex core position) of the nano-oscillator. Thus, we show that the Ampère-Oersted field should not be neglected as it has a high impact on the spin-torque vortex oscillator dynamics.
PubMed: 35739153
DOI: 10.1038/s41598-022-14574-3 -
Nature Communications Oct 2023Extreme fast charging of Ampere-hour (Ah)-scale electrochemical energy storage devices targeting charging times of less than 10 minutes are desired to increase...
Extreme fast charging of Ampere-hour (Ah)-scale electrochemical energy storage devices targeting charging times of less than 10 minutes are desired to increase widespread adoption. However, this metric is difficult to achieve in conventional Li-ion batteries due to their inherent reaction mechanism and safety hazards at high current densities. In this work, we report 1 Ah soft-package potassium-ion hybrid supercapacitors (PIHCs), which combine the merits of high-energy density of battery-type negative electrodes and high-power density of capacitor-type positive electrodes. The PIHC consists of a defect-rich, high specific surface area N-doped carbon nanotube-based positive electrode, MnO quantum dots inlaid spacing-expanded carbon nanotube-based negative electrode, carbonate-based non-aqueous electrolyte, and a binder- and current collector-free cell design. Through the optimization of the cell configuration, electrodes, and electrolyte, the full cells (1 Ah) exhibit a cell voltage up to 4.8 V, high full-cell level specific energy of 140 Wh kg (based on the whole mass of device) with a full charge of 6 minutes. An 88% capacity retention after 200 cycles at 10 C (10 A) and a voltage retention of 99% at 25 ± 1 °C are also demonstrated.
PubMed: 37828005
DOI: 10.1038/s41467-023-42108-6 -
The Journal of Microwave Power and... 2012
Topics: Diathermy; Heating; Materials Testing; Microwaves
PubMed: 24427861
DOI: 10.1080/08327823.2012.11689817 -
Pacing and Clinical Electrophysiology :... Jul 2016Cardiac resynchronization defibrillator (CRT-D) devices improve survival for New York Heart Association classes II-IV systolic heart failure patients with QRS > 120 ms... (Review)
Review
BACKGROUND
Cardiac resynchronization defibrillator (CRT-D) devices improve survival for New York Heart Association classes II-IV systolic heart failure patients with QRS > 120 ms and left ventricular ejection fraction < 35%. A limitation of 100% CRT pacing is excess battery depletion and pulse generator (PG) replacement compared to VVI or dual-chamber systems. Ampere hour (Ah) measures PG battery capacity and may predict CRT-D device longevity.
METHODS
We performed a multicenter retrospective study of all CRT-D devices implanted at our centers from August 1, 2008 to December 31, 2010. Analysis was performed for survival to elective replacement indicator (ERI) between 1.0 Ah, 1.4 Ah, and 2.0 Ah devices, per manufacturers' specifications.
RESULTS
One thousand three hundred and two patients were studied through December 31, 2014. Patients were followed for an average of 3.0 ± 1.3 years (794 1.0 Ah, 322 2.0 Ah, and 186 1.4 Ah devices under study). CRT-D generator ERI occurred in 13.5% of 1.0 Ah systems (107 out of 794), versus 3.8% in 1.4 Ah (seven out of 186), and 0.3% in 2.0 Ah devices (one out of 322) over mean follow-up of 3.0 years. Odds ratio (OR) for reaching ERI with 1.0 Ah device versus 1.4 Ah or 2.0 Ah was 9.73, P < 0.0001. Univariate predictors for ERI included 1.0 Ah device and LV pacing output >3V @ 1 ms (OR: 3.74, P < 0.001). LV impedance >1,000 ohms predicted improved device survival (OR: 0.38, P = 0.0025).
CONCLUSIONS
CRT-D battery capacity measured by Ah is a strong predictor of survival to ERI for modern systems. Further study on cost and morbidity associated with early PG change in 1.0 Ah systems is warranted.
Topics: Aged; Cardiac Resynchronization Therapy Devices; Defibrillators, Implantable; Device Removal; Electric Power Supplies; Energy Transfer; Equipment Failure; Equipment Failure Analysis; Female; Heart Failure; Humans; Male; Prevalence; Retrospective Studies; United States
PubMed: 26875541
DOI: 10.1111/pace.12831 -
ACS Nano Nov 2023Electrochemical conversion of NO into NH (NORR) holds an enormous prospect to simultaneously yield valuable NH and alleviate NO pollution. Herein, we report...
Electrochemical conversion of NO into NH (NORR) holds an enormous prospect to simultaneously yield valuable NH and alleviate NO pollution. Herein, we report monodispersed Bi-doped FeS (Bi-FeS) as a highly effective NORR catalyst. Atomic coordination characterizations of Bi-FeS disclose that the isolated Bi dopant coordinates with its adjacent Fe atom to create the unconventional p-d hybridized Bi-Fe dinuclear sites. Operando spectroscopic measurements combined with theoretical calculations disclose that Bi-Fe dinuclear sites can synergistically enhance the hydrogenation energetics of NO-to-NH pathway, while suppressing the competitive hydrogen evolution, leading to a high NORR selectivity and activity. Consequently, the specially designed flow cell equipped with Bi-FeS exhibits a high NH yield rate of 83.7 mg h cm with a near-100% NO-to-NH Faradaic efficiency at an ampere-level current density of 1023.2 mA cm, together with an excellent long-term stability for 100 h of electrolysis, ranking almost the highest performance among all reported NORR catalysts.
PubMed: 37870919
DOI: 10.1021/acsnano.3c05946 -
Optics Express May 2023The paper presents a novel fiber-optic vector magnetic field sensor using a Fabry-Perot interferometer, which consists of an optical fiber end face and a graphene/Au...
The paper presents a novel fiber-optic vector magnetic field sensor using a Fabry-Perot interferometer, which consists of an optical fiber end face and a graphene/Au membrane suspended on the ceramic ferrule end face. A pair of gold electrodes are fabricated on the ceramic ferrule by femtosecond laser to transmit electrical current to the membrane. Ampere force is generated when an electrical current flows through the membrane in a perpendicular magnetic field. The change in Ampere force causes a shift in the resonance wavelength in the spectrum. In the magnetic field intensity range of 0 ∼ 180 mT and 0 ∼ -180 mT, the as-fabricated sensor exhibits magnetic field sensitivity of 5.71 pm/mT and 8.07 pm/mT. The proposed sensor has great potential application in weak magnetic field measurements due to its compact structure, cost-effectiveness, ease to manufacture, and good sensing performance.
PubMed: 37381576
DOI: 10.1364/OE.491629 -
Nature Communications Dec 2022The development of electrocatalysts capable of efficient reduction of nitrate (NO) to ammonia (NH) is drawing increasing interest for the sake of low carbon emission and...
The development of electrocatalysts capable of efficient reduction of nitrate (NO) to ammonia (NH) is drawing increasing interest for the sake of low carbon emission and environmental protection. Herein, we present a CuCo bimetallic catalyst able to imitate the bifunctional nature of copper-type nitrite reductase, which could easily remove NO via the collaboration of two active centers. Indeed, Co acts as an electron/proton donating center, while Cu facilitates NO adsorption/association. The bio-inspired CuCo nanosheet electrocatalyst delivers a 100 ± 1% Faradaic efficiency at an ampere-level current density of 1035 mA cm at -0.2 V vs. Reversible Hydrogen Electrode. The NH production rate reaches a high activity of 4.8 mmol cm h (960 mmol g h). A mechanistic study, using electrochemical in situ Fourier transform infrared spectroscopy and shell-isolated nanoparticle enhanced Raman spectroscopy, reveals a strong synergy between Cu and Co, with Co sites promoting the hydrogenation of NO to NH via adsorbed *H species. The well-modulated coverage of adsorbed *H and *NO led simultaneously to high NH selectivity and yield.
Topics: Ammonia; Hydrogenation; Adsorption; Carbon; Nitrite Reductases
PubMed: 36550156
DOI: 10.1038/s41467-022-35533-6 -
Micromachines Oct 2022The memristor is one of the modern microelectronics key devices. Due to the nanometer scale and complex processes physic, the development of memristor state study...
The memristor is one of the modern microelectronics key devices. Due to the nanometer scale and complex processes physic, the development of memristor state study approaches faces limitations of classical methods to observe the processes. We propose a new approach to investigate the degradation of six Ni/SiN/p+Si-based memristors up to their failure. The basis of the proposed idea is the joint analysis of resistance change curves with the volt-ampere characteristics registered by the auxiliary signal. The paper considers the existence of stable switching regions of the high-resistance state and their interpretation as stable states in which the device evolves. The stable regions' volt-ampere characteristics were simulated using a compact mobility modification model and a first-presented target function to solve the optimization problem.
PubMed: 36296044
DOI: 10.3390/mi13101691 -
Science (New York, N.Y.) Dec 1898
PubMed: 17829644
DOI: 10.1126/science.8.207.858 -
Angewandte Chemie (International Ed. in... Oct 2022Electrochemical conversion of CO into valuable feedstocks is a promising strategy for carbon neutrality. However, it remains a challenge to possess a large current...
Electrochemical conversion of CO into valuable feedstocks is a promising strategy for carbon neutrality. However, it remains a challenge to possess a large current density, a high faradaic efficiency and excellent stability for practical applications of CO utilization. Herein, we report a facile tactic that enables exceedingly efficient CO electroreduction to CO by virtue of low-coordination chloride ion (Cl ) adsorption on a silver hollow fiber (Ag HF) electrode. A CO faradaic efficiency of 92.3 % at a current density of one ampere per square centimeter (1 A cm ) in 3.0 M KCl with a sustained performance observed during a 150-hour test was achieved, which is better than state-of-the-art electrocatalysts. The electrochemical results and density functional theory (DFT) calculations suggested a low-coordination Cl adsorption on surface of Ag HF, which not only suppressed the competitive hydrogen evolution reaction (HER), but also facilitated the CO reduction kinetics.
PubMed: 36056915
DOI: 10.1002/anie.202210432