12 Search Results

Abstract Fourier partial sum approximations yield exponential accuracy for smooth and periodic functions, but produce the infamous Gibbs phenomenon for non-periodic ones. Spectral reprojection resolves the Gibbs phenomenon by projecting the Fourier partial sum onto a Gibbs complementary basis, often prescribed as the Gegenbauer polynomials. Noise in the Fourier data and the Runge phenomenon both degrade the quality of the Gegenbauer reconstruction solution, however. Motivated by its theoretical convergence properties, this paper proposes a new Bayesian framework for spectral reprojection, which allows a greater understanding of the impact of noise on the reprojection method from a statistical point of view. We are also able to improve the robustness with respect to the Gegenbauer polynomials parameters. Finally, the framework provides a mechanism to quantify the uncertainty of the solution estimate.

The pursuit of high-performance and long-lasting protonic ceramic electrochemical cells (PCECs) is impeded by the lack of efficient and enduring proton conductors. Conventional research approaches, predominantly based on a trial-and-error methodology, have proven to be demanding of resources and time-consuming. Here, this work reports the findings in harnessing high-throughput computational methods to expedite the discovery of optimal electrolytes for PCECs. This work methodically computes the oxygen vacancy formation energy (E_V), hydration energy (E_H), and the adsorption energies of H₂O and CO₂ for a set of 932 oxide candidates. Notably, these findings highlight BaSn_xCe_0.8-xYb_0.2O_3-δ (BSCYb) as a prospective game-changing contender, displaying superior proton conductivity and chemical resilience when compared to the well-regarded BaZr_xCe_0.8-xY_0.1Yb_0.1O_3-δ (BZCYYb) series. Experimental validations substantiate the computational predictions; PCECs incorporating BSCYb as the electrolyte achieved extraordinary peak power densities in the fuel cell mode (0.52 and 1.57 W cm^–2 at 450 and 600 °C, respectively), a current density of 2.62 A cm^–2 at 1.3 V and 600 °C in the electrolysis mode while demonstrating exceptional durability for over 1000-h when exposed to 50% H₂O. This research underscores the transformative potential of high-throughput computational techniques in advancing the field of proton-conducting oxides for sustainable power generation and hydrogen production.

Reversible proton-conducting solid oxide cells (R-PSOCs) have the potential to be the most efficient and cost-effective electrochemical device for energy storage and conversion. A breakthrough in air electrode material development is vital to minimizing the energy loss and degradation of R-PSOCs. Here we report a class of triple-conducting air electrode materials by judiciously doping transition- and rare-earth metal ions into a proton-conducting electrolyte material, which demonstrate outstanding activity and durability for R-PSOC applications. The optimized composition Ba_0.9Pr_0.1Hf_0.1Y_0.1Co_0.8O_3-δ (BPHYC) consists of three phases, which have a synergistic effect on enhancing the performance, as revealed from electrochemical analysis and theoretical calculations. When applied to R-PSOCs operated at 600 °C, a peak power density of 1.37 W cm^–2 is demonstrated in the fuel cell mode, and a current density of 2.40 A cm^–2 is achieved at a cell voltage of 1.3 V in the water electrolysis mode under stable operation for hundreds of hours.

Reversible solid oxide cells based on proton conductors (P-ReSOCs) have potential to be the most efficient and low-cost option for large-scale energy storage and power generation, holding promise as an enabler for the implementation of intermittent renewable energy technologies and the widespread utilization of hydrogen. Here, the rational design of a new class of hexavalent Mo/W-doped proton-conducting electrolytes with excellent durability while maintaining high conductivity is reported. Specifically, BaMo(W)_0.03Ce_0.71Yb_0.26O_3-δ exhibits dramatically enhanced chemical stability against high concentrations of steam and carbon dioxide than the state-of-the-art electrolyte materials while retaining similar ionic conductivity. In addition, P-ReSOCs based on BaW_0.03Ce_0.71Yb_0.26O_3-δ demonstrate high peak power densities of 1.54, 1.03, 0.72, and 0.48 W cm^–2 at 650, 600, 550, and 500 °C, respectively, in the fuel cell mode. During steam electrolysis, a high current density of 2.28 A cm^–2 is achieved at a cell voltage of 1.3 V at 600 °C, and the electrolysis cell can operate stably with no noticeable degradation when exposed to high humidity of 30% H₂O at –0.5 A cm^–2 and 600 °C for over 300 h. Altogether, this work demonstrates the promise of donor doping for obtaining proton conductors with both high conductivity and chemical stability for P-ReSOCs.

Abstract Reversible solid oxide cells based on proton conductors (P‐ReSOCs) have potential to be the most efficient and low‐cost option for large‐scale energy storage and power generation, holding promise as an enabler for the implementation of intermittent renewable energy technologies and the widespread utilization of hydrogen. Here, the rational design of a new class of hexavalent Mo/W‐doped proton‐conducting electrolytes with excellent durability while maintaining high conductivity is reported. Specifically, BaMo(W)_0.03Ce_0.71Yb_0.26O_3‐δexhibits dramatically enhanced chemical stability against high concentrations of steam and carbon dioxide than the state‐of‐the‐art electrolyte materials while retaining similar ionic conductivity. In addition, P‐ReSOCs based on BaW_0.03Ce_0.71Yb_0.26O_3‐δdemonstrate high peak power densities of 1.54, 1.03, 0.72, and 0.48 W cm⁻²at 650, 600, 550, and 500 °C, respectively, in the fuel cell mode. During steam electrolysis, a high current density of 2.28 A cm⁻²is achieved at a cell voltage of 1.3 V at 600 °C, and the electrolysis cell can operate stably with no noticeable degradation when exposed to high humidity of 30% H₂O at −0.5 A cm⁻²and 600 °C for over 300 h. Overall, this work demonstrates the promise of donor doping for obtaining proton conductors with both high conductivity and chemical stability for P‐ReSOCs.

Proton-conducting electrolytes are receiving increasing attention due to their high ionic conductivity at intermediate temperatures, enabling the operation of solid oxide cells with high energy efficiency at low cost. However, the effect of B-site dopants on the properties of doped barium hafnate-cerate electrolyte materials, especially in single cells under operating conditions, has not been systematically studied. Here we report our findings in the development of a series of proton-conducting electrolytes with a general formula of BaHf_0.1Ce_0.7R_0.2O_3–δ (BHCR172, R = Yb, Er, Y, Gd, Sm). Here, the results reveal that electrical conductivity, ionic transference number, chemical stability against steam and CO₂, and compatibility with NiO during sintering are all closely correlated with the dopant size. In particular, the reaction with NiO is found to strongly affect the properties of the electrolytes and hence cell performance. Among all tested compositions, BaHf_0.1Ce_0.7Yb_0.2O_3–δ (BHCYb172) shows excellent chemical stability and minimal reactivity towards NiO, as predicted from density functional theory (DFT)-based calculations and confirmed by experimental results. In addition, proton-conducting reversible solid oxide cells (P-ReSOCs) based on the optimized electrolyte composition, BHCYb172, demonstrate exceptional performance and stability, achieving a remarkable peak power density of 1.74 W cm^–2 (O₂ as the oxidant) at 600 °C in the fuel cell mode and a high current density of 2.0 A cm^–2 at 1.3 V and 600 °C in the steam electrolysis mode while maintaining excellent durability for over 1000 h.

Solid oxide cells (SOCs) are considered the most efficient system for reversible conversion between chemical and electrical energy, thus having potential to be an attractive technology for a sustainable energy future. To achieve high round-trip efficiency, highly efficient and durable air electrode materials are needed to minimize energy loss associated with oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Here we report a bi-functional air electrode material, PrBa_0.9Co_1.96Nb_0.04O_5+δ, demonstrating outstanding electrochemical performance (e.g., achieving peak power densities of over 1.5 and 1 W cm^–2, respectively, for Gd_0.1Ce_0.9O_1.95 and BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ based fuel cells at 600 °C) while maintaining excellent stability (e.g., having a degradation rate of 40 mV per 1,000 h for H₂O electrolysis cells). Finally, the excellent property of the new electrode is attributed to the improved stability from Nb doping and the enhanced electrocatalytic activity from tuning Ba deficiency, as confirmed by experimental results and computational analysis.

Highlights: • We integrated transcriptome of spermatogenesis and found miRNA regulate spermatogenesis through miRNA editing. • We compared with different species and found that the distribution of miRNA editing during spermatogenesis is conservative. • We identified miR-34c, which is edited frequently at all stages during spermatogenesis, regulates its target genes through the RNA structure changing and shows dysfunction when it is edited. Spermatogenesis has a close relationship with male infertility. MicroRNAs (miRNAs) play crucial roles in their regulation of target genes during spermatogenesis. A huge dataset of high-throughput sequencing all over the world provides the basis to dig the cryptic molecular mechanism. But how to take advantage of the big data and unearth the miRNA regulation is still a challenging problem. Here we integrated transcriptome of spermatogenesis and found miRNA regulate spermatogenesis through miRNA editing. We then compared different species and found that the distributions of miRNA editing site number and editing types among different cell types during spermatogenesis are conservative. Interesting, we further found that nearly half of the editing events occurred in the seed region in both mouse and pig. Finally, we foundmiR-34c, which is edited frequently at all stages during spermatogenesis, regulates its target genes through the RNA structure changing and shows dysfunction when it is edited. Summary, we depicted the overall profile of miRNA editing during spermatogenesis in mouse and pig and reveal miR-34c may play its roles through miRNA editing.

We design a dual-band absorber formed by combining two cross-shaped metallic resonators of different sizes within a super-unit-cell arranged in mirror symmetry. Simulations indicate that absorption efficiencies greater than 99% can be achieved at two different frequencies under normal incidence. We also employ a design scheme with graphene integration, which allows independent tuning of individual absorption frequencies by electrostatically changing the Fermi energy of the graphene layer. High absorbance is maintained over a wide incident angle range up to 50 degrees for both TE and TM polarizations. Thus, it enables a promising way to design electrically tunable absorbers, which may contribute toward the realization of frequency selective detectors for sensing applications.