In this paper, we study piezoelectric materials with multiscale porous microstructure. Piezoelectric materials have wide applications in modern electronic devices, while the porous microstructure can be beneficial for specific applications, such as ultrasonic transducers. For the numerical simulation of such materials, homogenization methods are widely employed to determine the effective material properties at each macroscopic point. However, their applicability becomes limited for materials with complex multiscale porous microstructures, where intricate microscale interactions cannot be adequately represented by standard homogenization frameworks. In this paper, we propose a multicontinuum modeling approach for porous piezoelectric materials based on multicontinuum homogenization. We introduce several interacting continua representing channels of different sizes and derive the corresponding multicontinuum model. To this end, we formulate multicontinuum expansions of the fine-scale mechanical displacement and electric potential based on macroscopic variables. Coupled constrained cell problems are then introduced to capture the effective homogenized behavior. Utilizing the corresponding cell solutions, we rigorously derive a generalized multicontinuum piezoelectricity model valid for an arbitrary number of continua. Numerical experiments involving model problems with two continua are presented to validate the proposed model.
Electrocatalytic water splitting represents a sustainable and efficient approach for producing high-purity hydrogen, playing an increasingly pivotal role in addressing global energy sustainability challenges. However, dynamic and complex electrocatalytic processes pose significant obstacles to unraveling electrocatalytic mechanisms and advancing catalyst design. This review first discusses fundamental principles for conducting reliable in situ/operando synchrotron radiation (SR) spectroscopic measurements in electrocatalytic systems, proposing guidelines for standardizing practices across the community. Then, cutting-edge in situ/operando SR-based spectroscopic techniques applied in electrocatalytic water splitting are systematically examined, highlighting their distinctive advantages while critically evaluating inherent methodological limitations. Moving beyond conventional single-technique approaches, we focus on complementary probes based on in situ/operando multi-SR spectroscopic technologies to achieve panoramic visualization of the dynamic evolution for the water splitting process, spanning from the atomic and molecular scales to the electronic level. Finally, key bottlenecks and frontier research opportunities are outlined, aiming to inspire a paradigm shift from fragmented analysis toward integrated, system-level mechanistic understanding in electrocatalytic water splitting.
This study presents a comprehensive investigation of the CoFe2O4–Pb2ScNbO6 (0.5CFO–0.5PSN) composite, synthesized via a solid-state reaction method. The composite, comprising a ferrite spinel and a relaxor ferroelectric, was characterized using a suite of techniques including dielectric spectroscopy, optical analysis, X-ray diffractometry, magnetometry, magnetodielectric measurements and electrocatalytic testing. At room temperature, the real part of the complex permittivity (ε′) attains a value of 105. Within the temperature range of 100–250 °C, ε′ increases significantly to approximately 1.4 × 106. The temperature dependence of permittivity, ε′(T), exhibits a relaxor behaviour, which is attributed to the diffuse phase transition inherent to the PSN component and contributions from Maxwell–Wagner interfacial polarization. A distinct anomaly in the ε′(T) curve is observed near 450 °C, manifested as a kink followed by a sharp increase. This feature is associated with the transition of the CFO component from a ferrimagnetic to a paramagnetic state. The analysis of the magnetoresistance coefficient, MR(H), reveals that the composite exhibits colossal magnetoresistance (CMR) on the order of 530
The Cd(ii) complexes with 2,4-dinitrobenzoate (2,4-dnb) or 3,5-dinitrobenzoate (3,5-dnb) anions and 1,10-phenanthroline (phen), 2,2′-bipyridine (bpy), and 4,4′-dimethyl-2,2′-bipyridine (Me2bpy) molecules of the composition [Cd(H2O)2(phen)(2,4-dnb)2] (1), [Cd2(bpy)2(2,4-dnb)4] (2), [Cd(Me2bpy)(2,4-dnb)2]n (3), [Cd2(H2O)2(Me2bpy)2(2,4-dnb)4] (4), [Cd2(phen)2(3,5-dnb)4]•2MeCN (5), and [Cd(H2O)(Me2bpy)(3,5-dnb)2]•THF (6) were studied. The influence of different factors on the composition and the structure of the new compounds was revealed by varying the combination of monocarboxylate anions and N-donor ligands and using different synthesis and crystallization conditions. A combination of 2,4-dinitrobenzoate anions with Me2bpy allowed the synthesis of coordination polymer 3 and binuclear complex 4, which is completed with water molecules, using the same chelating ligand. Therefore, this system was studied by quantum chemical calculations. These calculations provided an explanation of the experimental results. The synthesized complexes were characterized by X-ray diffraction, IR spectroscopy, and CHN elemental analysis. The structures and the crystal packing of the new complexes were analyzed in detail. The main structure-forming non-covalent interactions in the crystals were identified.
The purpose of the experiment was to identify nutrient management strategy to improve proso millet yield and mitigate greenhouse gas emissions. Especially by quantifying how chemical fertilizers and integrated nutrient management influence yield and greenhouse gas emissions. Five nutrient management treatments i.e., CK (0 kg N ha⁻¹), N1 (100 kg N ha⁻¹, urea), N2 (140 kg N ha⁻¹, urea), N1M (50 kg N ha⁻¹ urea + 50 kg N ha⁻¹ cattle manure), and N2M (70 kg N ha⁻¹ urea + 70 kg N ha⁻¹ cattle manure) were evaluated for greenhouse gas emissions and proso millet yield. Nutrient management significantly affected greenhouse gas emissions and proso millet yield. N1M significantly improved growth and proso millet yield (+ 48.4
