Local Structure Research Articles

A novel locally resonance metamaterial cylindrical shell with tower-shaped lattice for broadband vibration suppression

Vibration issues in cylindrical shells are prevalent in engineering applications and can significantly impact the operational performance of systems. To address these challenges, this paper designs a novel local resonance tower structure, and establishes an analytical model to investigate vibration characteristics of the metamaterial cylindrical shell. Based on the model, a gradient design strategy is proposed to improve vibration suppression properties over a wide frequency range. Firstly, the governing equations of the cylindrical shell are derived and the dispersion analysis is conducted to predict the bandgap boundaries using the extended plane wave expansion (EPWE) method. Then, for a finite-period metamaterial cylindrical shell with specific boundary conditions, the frequency response of the structure is obtained by finite element calculations to show the bandgap behavior. The results of these two methods are basically the same. In addition, the effects of frequency spacing, damping and array period on the vibration characteristics are considered comprehensively. The results show that a wider and more stable attenuation range can be obtained by reasonably adjusting these three parameters. Finally, the comparison between experimental and numerical calculations verify that the tower structure is effective, and that the proposed design strategy can broaden the vibration attenuation region.

Machine learning for efficient grazing-exit x-ray absorption near edge structure spectroscopy analysis: Bayesian optimization approach

In materials science, traditional techniques for analyzing layered structures are essential for obtaining information about local structure, electronic properties and chemical states. While valuable, these methods often require high vacuum environments and have limited depth profiling capabilities. The grazing exit x-ray absorption near-edge structure (GE-XANES) technique addresses these limitations by providing depth-resolved insight at ambient conditions, facilitating in situ material analysis without special sample preparation. However, GE-XANES is limited by long data acquisition times, which hinders its practicality for various applications. To overcome this, we have incorporated Bayesian optimization (BO) into the GE-XANES data acquisition process. This innovative approach potentially reduces measurement time by a factor of 50. We have used a standard GE-XANES experiment, which serve as reference, to validate the effectiveness and accuracy of the BO-informed experimental setup. Our results show that this optimized approach maintains data quality while significantly improving efficiency, making GE-XANES more accessible to a wider range of materials science applications.

Manipulating Local Chemistry and Coherent Structures for High-Rate and Long-Life Sodium-Ion Battery Cathodes.

Layered sodium transition-metal (TM) oxides generally suffer from severe capacity decay and poor rate performance during cycling, especially at a high state of charge (SoC). Herein, an insight into failure mechanisms within high-voltage layered cathodes is unveiled, while a two-in-one tactic of charge localization and coherent structures is devised to improve structural integrity and Na+ transport kinetics, elucidated by density functional theory calculations. Elevated Jahn-Teller [Mn3+O6] concentration on the particle surface during sodiation, coupled with intense interlayer repulsion and adverse oxygen instability, leads to irreversible damage to the near-surface structure, as demonstrated by X-ray absorption spectroscopy and in situ characterization techniques. It is further validated that the structural skeleton is substantially strengthened through the electronic structure modulation surrounding oxygen. Furthermore, optimized Na+ diffusion is effectively attainable via regulating intergrown structures, successfully achieved by the Zn2+ inducer. Greatly, good redox reversibility with an initial Coulombic efficiency of 92.6%, impressive rate capability (86.5 mAh g-1 with 70.4% retention at 10C), and enhanced cycling stability (71.6% retention after 300 cycles at 5C) are exhibited in the P2/O3 biphasic cathode. It is believed that a profound comprehension of layered oxides will herald fresh perspectives to develop high-voltage cathode materials for sodium-ion batteries.

Metal Doping Regulates Electrocatalysts Restructuring during Oxygen Evolution Reaction.

High-efficiency and low-cost catalysts for oxygen evolution reaction (OER) are critical for electrochemical water splitting to generate hydrogen, which is a clean fuel for sustainable energy conversion and storage. Among the emerging OER catalysts, transition metal dichalcogenides have exhibited superior activity compared to commercial standards such as RuO2, but inferior stability due to uncontrolled restructuring with OER. In this study, we create bimetallic sulfide catalysts by adapting the atomic ratio of Ni and Co in CoxNi1-xSy electrocatalysts to investigate the intricate restructuring processes. Surface-sensitive X-ray photoelectron spectroscopy and bulk-sensitive X-ray absorption spectroscopy confirmed the favorable restructuring of transition metal sulfide material following OER processes. Our results indicate that a small amount of Ni substitution can reshape the Co local electronic structure, which regulates the restructuring process to optimize the balance between OER activity and stability. This work represents a significant advancement in the development of efficient and noble metal-free OER electrocatalysts through a doping-regulated restructuring approach.

ATENA: A Web-Based Tool for Modelling Metal Oxide Nanoparticles Based on NanoFingerprint Quantitative Structure–Activity Relationships

Modelling size-realistic nanomaterials to analyse some of their properties, such as toxicity, solubility, or electronic structure, is a current challenge in computational and theoretical chemistry. The representation of the all-atom three-dimensional structure of a nanocompound would be ideal, as it could account explicitly for structural effects. However, the use of the whole structure is tedious due to the high data management and the structural complexity that accompanies the surface of the nanoparticle. Developing appropriate tools that enable a quantitative analysis of the structure, as well as the selection of regions of interest such as the core-shell, is a crucial step toward enabling the efficient analysis and processing of model nanostructures. The aim of this study was twofold. First, we defined the NanoFingerprint, which is a representation of a nanocompound in the form of a vector based on its 3D structure. The local relationship between atoms, i.e., their coordination within successive layers of neighbours, allows the characterisation of the local structure through the atom connectivity, maintaining the information of the three-dimensional structure but increasing the management ability. Second, we present a web server, called ATENA, to generate NanoFingerprints and other tools based on the 3D structure of the nanocompounds. A case study is reported to show the validity of our new fingerprint tool and the usefulness of our server. The scientific community and also private companies have a new tool based on a public web server for exploring the toxicity of nanocompounds.

Computational Insights on Structural Sensitivity of Cobalt in NO Electroreduction to Ammonia and Hydroxylamine.

It has been reported that it was selective to produce ammonia on metallic cobalt in the electrocatalytic nitric oxide reduction reaction (eNORR), where hexagonal close-packed (hcp) cobalt outperforms face-centered cubic (fcc) cobalt. However, hydroxylamine is more selectively produced on a cobalt single-atom catalyst (Co-SAC). Herein, we uncover the structural sensitivity over hcp-Co, fcc-Co, and Co-SAC in eNORR by employing a recently developed constant potential simulation method and microkinetic modeling. It was found that the superior activity for ammonia production on hcp-Co can be attributed to its facile electron and proton transfer and a stronger lateral suppression effect from NO* over fcc-Co. The exceptional hydroxylamine selectivity on Co-SAC is due to the modified electronic structure, namely, a positively charged active center. It was found that it is more favorable to produce NOH* over hcp-Co and fcc-Co, while HNO* is more preferable on Co-SAC, which are firmly correlated with the vertical and strong NO adsorption on the former and the moderate adsorption on the latter. In other words, a key factor for selectivity control is the first step of NO* protonation. Therefore, the local structure and electronic structure of the catalysts can be critical in regulating the activity and selectivity in eNORR.

Investigation on temperature effect of local structural stress during non-uniform cross-section steel bridge deck pavement paving

During the process of gussasphalt concrete paving on the orthotropic steel bridge deck of a non-uniform cross-section box girder bridge, the high-temperature asphalt mixture often produces temperature stresses that can affect bearings safety. In this study, a refined model of a steel box girder bridge with a 660 m scale was developed and numerical simulations were conducted using the finite element software. The temperature field was applied to the orthotropic steel bridge deck in a quasi-dynamic fashion, leading to the determination of a safe width for concrete paving. To assess the accuracy of the computational predictions, field paving was performed under the safe width condition determined from the calculations, and the temperature and local stress data were measured in the field. The results demonstrate that the finite element predictions are in good agreement with the yield strength of the bearing’s local structure, and the measurements also show a close correspondence with the structural yield strength, validating the reliability of the quasi-static simulation approach. The proposed method offers a computational tool and a reliability criterion for future finite element analyses of large-span non-uniform cross-section steel box girder bridges, as well as a safe width example for subsequent gussasphalt mixture paving on orthotropic steel bridge decks.

Adaptive parameter local consistency automatic outlier removal algorithm for area-based matching

Abstract. Due to the influence of image differences and matching methods, geometric calibration of remote sensing images often results in the extraction of control points with inevitable outliers. Moreover, it is susceptible to limitations imposed by locally constrained outlier rejection methods, making it challenging to automatically remove relatively small gross errors. This paper introduces an adaptive parameter local consistency automatic outlier removal algorithm, referred to as APLC. Initially, we construct k-nearest neighbors for each pair of matching points, deriving distance and topological uncertainty based on the accuracy of point matching. Subsequently, we conduct cross-validation on the uncertainty between the two pairs of vectors formed by points within the neighborhood, aiming for parameter adaptation. Finally, a cost-defined function is introduced to assess the consistency of local structures. Through a two-stage outlier removal strategy, matching points that do not maintain local structural consistency are eliminated. To assess the effectiveness of the proposed algorithm, we conduct experimental comparisons using region-based initial matching results from the FY-3D remote sensing dataset, demonstrating its superiority compared to three state-of-the-art methods.

Oxygen Vacancies Trigger Rapid Charge Transport Channels at the Engineered Interface of S-scheme Heterojunction for Boosting Photocatalytic Performance.

Although oxygen vacancies (Ovs) have been intensively studied in single semiconductor photocatalysts, exploration of intrinsic mechanisms and in-depth understanding of Ovs in S-scheme heterojunction photocatalysts are still limited. Herein, a novel S-scheme photocatalyst made from WO3-Ov/In2S3 with Ovs at the heterointerface is rationally designed. The microscopic environment and local electronic structure of the S-scheme heterointerface are well optimized by Ovs. Femtosecond transient absorption spectroscopy (fs-TAS) reveals that Ovs trigger additional charge movement routes and therefore increase charge separation efficiency. In addition, Ovs have a synergistic effect on the thermodynamic and kinetic parameters of S-scheme photocatalysts. As a result, the optimal photocatalytic performance is significantly improved, surpassing that of single component WO3-Ov and In2S3 (by 35.5 and 3.9 times, respectively), as well as WO3/In2S3 heterojunction. This work provides new insight into regulating the photogenerated carrier dynamics at the heterointerface and also helps design highly efficient S-scheme photocatalysts.

Oxygen Vacancies Trigger Rapid Charge Transport Channels at the Engineered Interface of S‐scheme Heterojunction for Boosting Photocatalytic Performance

Although oxygen vacancies (Ovs) have been intensively studied in single semiconductor photocatalysts, exploration of intrinsic mechanisms and in‐depth understanding of Ovs in S‐scheme heterojunction photocatalysts are still limited. Herein, a novel S‐scheme photocatalyst made from WO3‐Ov/In2S3 with Ovs at the heterointerface is rationally designed. The microscopic environment and local electronic structure of the S‐scheme heterointerface are well optimized by Ovs. Femtosecond transient absorption spectroscopy (fs‐TAS) reveals that Ovs trigger additional charge movement routes and therefore increase charge separation efficiency. In addition, Ovs have a synergistic effect on the thermodynamic and kinetic parameters of S‐scheme photocatalysts. As a result, the optimal photocatalytic performance is significantly improved, surpassing that of single component WO3‐Ov and In2S3 (by 35.5 and 3.9 times, respectively), as well as WO3/In2S3 heterojunction. This work provides new insight into regulating the photogenerated carrier dynamics at the heterointerface and also helps design highly efficient S‐scheme photocatalysts.

Metallic Ru─Ru Interaction in Ruthenium Oxide Enabling Durable Proton Exchange Membrane Water Electrolysis.

Developing efficient and robust electrocatalysts toward the oxygen evolution reaction (OER) is critical for proton exchange membrane water electrolysis (PEMWE). RuO2 possesses intrinsically high OER activity, but the concurrent electrochemical dissolution leads to rapid deactivation. Here a unique RuO2 catalyst containing metallic Ru─Ru interactions (m-RuO2) is reported, which maintains stability in practical PEMWE for 100h at 60 °C and 1 A cm-2. Experimental and theoretical investigations suggest that the presence of Ru─Ru interactions significantly increases the energy barrier for the formation of RuO2(OH)2, which is a key intermediate for Ru dissolution, and hence substantially mitigates the electrochemical corrosion of m-RuO2. Meanwhile, the Ru4d band center downshifts, accordingly, ensuring the high OER activity, and the participation of lattice oxygen in the OER is also suppressed at the Ru─Ru sites, further contributing to the enhanced durability. Interestingly, such enhanced stability is also dependent on the size of metallic Ru─Ru cluster, where the energy barrier is further increased for Ru3, but is decreased for Ru5. These results highlight the significance of local coordination structure modulation on the electrochemical stability of RuO2 and open a feasible avenue toward the development of robust OER electrocatalysts for high-performance PEMWE.

Bond Structure Engineering Induced the Mn Redox Stabilization Toward High‐Energy Mn‐Based Phosphate Cathode

AbstractManganese (Mn) ‐based phosphate is poised for commercial applications driven by its cost‐effectiveness, robust NASICON framework, and multi‐dimensional Na+ pathways. However, it encounters insufficient redox reactions and rapid structural collapse with severe lattice distortion as the culprit. Herein, one meticulously engineered substitutional solid solution cathode (integrating Na4MnCr(PO4)3 and Na3MnTi(PO4)3, denoted NMCTP) is proposed to regulate the local crystal structure of Mn─O bond to stabilize and promote the Mn redox reaction for optimizing the electrochemical performance. It is uncovered that the bulk framework with structural stability is constructed by strongly symmetric Mn─O bond lengths of MnO6 octahedrons and strengthened Mn─O covalency. In addition, the sufficient utilization of Mn redox is tightly correlated with redistributed Na2 occupancy and enhanced diffusion kinetics with accelerated electron transportation. By virtue of the above merits, The NMCTP performs ultra‐high capacity (150.3 mAh g−1 at 0.1 C) and appealing cycling stability (84.7% retention over 1000 cycles). Sodium storage mechanisms and potential factors at high potentials are unveiled in NMCTP materials. This work sheds light on fire‐new solid solution strengthening in view of the Mn─O bond structure for high‐performance Mn‐based phosphate cathodes.

An overview of ion-acoustic solitary and shock waves in a magnetized nonthermal plasma: influence of trapped positrons and electrons

A magnetized nonthermal electron–positron-ion (e-p-i) plasma is considered to study the propagation properties of ion-acoustic solitary and shock waves in the presence of trapped positrons and electrons for the first time. The Schamel-κ (kappa) distribution function that describes plasma nonthermality and particle trapping is assumed to consider electrons and positrons. The diffusive effect of ion plasma fluid, which is responsible for shock dynamics, is taken into account. A nonlinear Schamel-Korteweg–de Vries-Burgers’ (SKdVB) equation is derived by employing the reductive perturbation approach, and the solitary and shock wave solutions of the SKdVB equation have also been derived for different limiting cases. It is found that only positive potential nonlinear structures (for both solitary and shock waves) are formed in the proposed plasma system. The condition for stable solitons in the absence of dissipation is analyzed, and the nature of arbitrary amplitude solitary waves (obtained via the Sagdeev potential approach) is discussed. It is found through theoretical and numerical investigation that different plasma compositional parameters (such as the trapping effect of electrons (β e ) and positrons (β p ), the obliquity effect (θ), electron-to-ion number density ratio (µ e ), the magnetic field effect (via Ω) and the viscous effect (via η)) have a significant influence on the dynamics of ion-acoustic solitary and shock waves. The theoretical and numerical investigations in this study may be helpful in describing the nature of localized structures in different plasma contexts, e.g. space and astrophysical plasmas and experimental plasmas where electron–positron-ion plasmas exist.

Effect of Calcination Temperature on Structure Evolution of Hematite Nanoparticles

Abstract This research aims to examine the transition structure of iron oxide, namely from magnetite to hematite, and the impact of calcination temperature on the structural development of hematite nanoparticles. The coprecipitation process was used to extract the magnetite from Indonesian local iron sand. Magnetite was calcined at several temperatures (350, 500, 650, and 800 °C) to produce hematite. Several characterization methods were combined to investigate the structure changes due to the effect of calcination temperature. The synchrotron X-ray diffraction (SRD) and X-ray absorption spectroscopy (XAS) techniques were used to investigate the crystal and local structure, respectively. The Debye-Schrerer equation at the most dominant SRD peak were used to determine the crystallite size. Meanwhile, scanning electron microscopy (SEM) performed to studied the surface morphology. The results of SRD showed that the Fe3O4 and α-Fe2O3 phases are visible in the sample calcined at 350°C, whereas the single-phase α-Fe2O3 was seen at higher temperatures. It was also observed that the crystallinity and crystallite size increased due to the increasing calcination temperature. The crystallite size increased from 9.57 to 29.55, 16.40, 28,48, 29.26, and 29.55 nm for the magnetite, H350, H500, H650, and H800 samples. Meanwhile, XAS fitting data found that higher calcination temperatures increase the interatomic distance but decrease the Debye-Waller factor. It can be concluded that the transformation from Fe3O4 to single-phase α-Fe2O3 was observed at 500oC. A higher calcination temperature of at least 800oC wouldn't change the phase but affect the structure parameters.

To copy verbatim, paraphrase or summarize – listeners’ methods of discourse representation while recalling academic lectures

Abstract It is unanimously agreed that comprehension of academic lectures is cognitively demanding; however, few studies have focused on a listener’s real-time discourse representation of a lecture. Based on the qualitative analysis of the verbal protocols, the present study investigated sixteen Chinese university students’ verbal recall of an academic mini-lecture to explore how they made sense of the lecture and represented its discourse when they recalled it episode by episode, and to what extent they differed in discourse representation. The results show that listeners’ discourse representation involved a range of cognitive processes such as paraphrasing, summarizing, and verbatim copying. Paraphrasing and summarizing were the main methods of discourse representation used by the participants when they verbally recalled the lecture. Those who correctly paraphrased more idea units recalled more content of the lecture. They were able to select and retain more idea units in their short-term memory, build more associations between the selected idea units, integrate them with the existing discourse structures and ensure contextual coherence in the construction of the local discourse structures. The findings of the study contribute to a better understanding of how listeners comprehend academic lectures and confirm that improving students’ paraphrasing skills and hierarchical discourse construction in recall are conducive to better comprehension of academic lectures.

Assessing Demographics, Perceptions, and Participation: A Study on Sangguniang Kabataan (SK) Effectiveness and Improvement Suggestions

The Sangguniang Kabataan is an important institution in the Philippines that represents the interests of youth and engages them in local governance. This study examines the perceptions of young Filipinos regarding the Sangguniang Kabataan’s (SK) participation in local government, focusing on understanding how youth perspectives influence the efficacy of SK initiatives. The research integrated a descriptive quantitative research design. A total of 32 participants were involved in the study, providing insights into their demographic profiles, perceptions of SK duties and functions, levels of participation in SK activities, and suggestions for improving SK officials and their activities. The findings reveal that while respondents generally recognize the importance of the SK in representing youth in local government, there are areas where its effectiveness can be enhanced, such as in implementing youth-focused programs and initiatives. The study also highlights barriers to youth participation in SK activities, including lack of awareness and time constraints. Recommendations for improving youth engagement in the SK include prioritizing advocacy for youth-related issues, enhancing communication with young individuals, and focusing on initiatives that address critical issues like poverty, education, and mental health. By implementing these recommendations, the SK can better serve the needs and aspirations of the youth population and create a more responsive and inclusive local governance structure.

Interfacial Spinel Local Interlocking Strategy Toward Structural Integrity in P3 Oxide Cathodes.

P3-layered transition oxide cathodes have garnered considerable attention owing to their high initial capacity, rapid Na+ kinetics, and less energy consumption during the synthesis process. Despite these merits, their practical application is hindered by the substantial capacity degradation resulting from unfavorable structural transformations, Mn dissolution and migration. In this study, we systematically investigated the failure mechanisms of P3 cathodes, encompassing Mn dissolution, migration, and the irreversible P3-O3' phase transition, culminating in severe structural collapse. To address these challenges, we proposed an interfacial spinel local interlocking strategy utilizing P3/spinel intergrowth oxide as a proof-of-concept material. As a result, P3/spinel intergrowth oxide cathodes demonstrated enhanced cycling performance. The effectiveness of suppressing Mn migration and maintaining local structure of interfacial spinel local interlocking strategy was validated through depth-etching X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and in situ synchrotron-based X-ray diffraction. This interfacial spinel local interlocking engineering strategy presents a promising avenue for the development of advanced cathode materials for sodium-ion batteries.

α-Hydrazino Acid Insertion Governs Peptide Organization in Solution by Local Structure Ordering

α-Hydrazino Acid Insertion Governs Peptide Organization in Solution by Local Structure Ordering

Subnanometer‐sized CuOx Clusters on TiO2 as Active Photocatalysts for Ammonia Production from Photocatalytic Nitration Reduction Reaction

The Haber‐Bosch process is commonly used to produce ammonia while consuming energy and yielding huge emissions of carbon dioxide. Finding an alternative way to produce ammonia sustainably is a promising research direction with less CO2 emission. Photochemical nitrate reduction reaction (NtRR) to ammonia (NH3) could solve the nitrate pollutant problem in water and approach to produce ammonia with a more environmentally friendly process and lower energy consumption. In this work, the subnanometer‐sized copper oxide clusters decorated on titanium oxide nanoparticles (CuOx‐TiO2) were synthesized through the hydrothermal method and calcination treatment. CuOx‐TiO2 demonstrated impressively conversion rate of NO3‐ to NH3 with a yield of 153.09 μg‐gcat‐1‐h‐1 in KNO3 solution. The characteristic structure analysis revealed CuOx clusters with ~less than 1 nm decorated on TiO2 nanoparticles. From in‐situ X‐ray absorption fine structure (XAFS) spectroscopic technique, the transformation of the oxidation state of Cu clusters and the changes of local structure in the CuOx‐TiO2 were observed. The photocatalytic reaction mechanism of nitrate reduction on the CuOx‐TiO2 was successfully revealed. These discoveries have broad implications for the functional advancement of catalysts based on subnanometer‐sized clusters. Our findings may pave the way for exploring advanced ammonia synthesis routes with reduced energy consumption and carbon emissions.

Inflection Point in Pressure Dependence of Ionic Conductivity as a Fingerprint of Local Structure Formation.

In this study, we employed dielectric spectroscopy to investigate the effect of temperature and pressure on the ion dynamics of phosphonium ionic liquids (ILs) differing by the length of an alkyl chain, [P666,n][TFSI] (n = 2, 6, 8, 12). We found that both temperature and pressure dependence of dc-conductivity (σdc) determined for all examined ILs herein exhibit unique characteristics, unusual for aprotic ILs. Two regions differing by ion self-organization have been identified from the derivative analysis of σdc(T-1) data. On the other hand, isothermal measurements performed at elevated pressure revealed a unique concave-convex character of σdc(P) dependences, resulting in a clear minimum in the pressure behavior of activation volume. Such an inflection point characterizing the pressure dependence of σdc in [P666,n][TFSI] ILs can be considered an inherent feature of ion dynamics governed by structural self-assembly. Our results offer a unique perspective to link the ion mobility at various T-P conditions to the nanostructural organization of ionic systems.