Ideal Structure Research Articles

Ultraviolet photodetector improvement based on microspheres

Owing to the ideal optical cavity structure, the microsphere has always played a significant role in micro/nano optoelectronic devices for its high light-confined ability and large surface-volume ratio, which have been applied in lots of areas including intracellular lasers, tunable lasers, and so on. Furthermore, the microsphere cavity will be a useful and efficient means to improve the photodetector (PD) performance by enhancing the light absorption efficiency and light energy in the arrays. Herein, the wide-bandgap semiconductor microspheres are introduced in the PD, which are synthesized by a simple and universal hydrothermal method. The sensitive ultraviolet PD is constructed and obtained with a metal-semiconductor-metal type device structure. The oxide defect concentration in the ZnO microspheres is modulated through thermal treatment to improve the performance, including higher photo-to-dark current ratio near 600, responsivity of 7.6✕10−5 A/W, detectivity of 4.6✕107 Jones, and response speed. Moreover, the microspheres fabricated flexible device presents great detecting performance with different bending degrees. The results display the excellent prospect of semiconductor microspheres to flexible ultraviolet high-performance PDs, which possess the broad and potential development prospect in flexible even on-chip optoelectronic devices.

LaMnO3-Type Perovskite Nanofibers as Effective Catalysts for On-Cell CH4 Reforming via Solid Oxide Fuel Cells.

CH4 has become the most attractive fuel for solid oxide fuel cells due to its wide availability, narrow explosion limit range, low price, and easy storage. Thus, we present the concept of on-cell reforming via SOFC power generation, in which CH4 and CO2 can be converted into H2 and the formed H2 is electrochemically oxidized on a Ni-BZCYYb anode. We modified the porosity and specific surface area of a perovskite reforming catalyst via an optimized electrostatic spinning method, and the prepared LCMN nanofibers, which displayed an ideal LaMnO3-type perovskite structure with a high specific surface area, were imposed on a conventional Ni-BZCYYb anode for on-cell CH4 reforming. Compared to LCMN nanoparticles used as on-cell reforming catalysts, the NF-SOFC showed lower ohmic and polarization resistances, indicating that the porous nanofibers could reduce the resistances of fuel gas transport and charge transport in the anode. Accordingly, the NF-SOFC displayed a maximum power density (MPD) of 781 mW cm-2 and a stable discharge voltage of around 0.62 V for 72 h without coking in the Ni-BZCYYb anode. The present LCMN NF materials and on-cell reforming system demonstrated stability and potential for highly efficient power generation with hydrocarbon fuels.

Search Me Knot, Render Me Knot: Embedding Search and Differentiable Rendering of Knots in 3D

AbstractWe introduce the problem of knot‐based inverse perceptual art. Given multiple target images and their corresponding viewing configurations, the objective is to find a 3D knot‐based tubular structure whose appearance resembles the target images when viewed from the specified viewing configurations. To solve this problem, we first design a differentiable rendering algorithm for rendering tubular knots embedded in 3D for arbitrary perspective camera configurations. Utilizing this differentiable rendering algorithm, we search over the space of knot configurations to find the ideal knot embedding. We represent the knot embeddings via homeomorphisms of the desired template knot, where the weights of an invertible neural network parametrize the homeomorphisms. Our approach is fully differentiable, making it possible to find the ideal 3D tubular structure for the desired perceptual art using gradient‐based optimization. We propose several loss functions that impose additional physical constraints, enforcing that the tube is free of self‐intersection, lies within a predefined region in space, satisfies the physical bending limits of the tube material, and the material cost is within a specified budget. We demonstrate through results that our knot representation is highly expressive and gives impressive results even for challenging target images in both single‐view and multiple‐view constraints. Through extensive ablation study, we show that each proposed loss function effectively ensures physical realizability. We construct a real‐world 3D‐printed object to demonstrate the practical utility of our approach.

Investigating the drag impact on pendulum through numerical models and the stability analysis

As a traditional physical model, the pendulum plays a crucial role in the dynamics. However, most research focuses on the ideal pendulum structure which deviates from reality. In order to study the pendulum in practical situations, this paper not only investigates the ideal model but also the simple pendulum motion with drag. Firstly, this work derived analytical and numerical solutions of the simple pendulum motion equations, which come from physical phenomena, and compared these two solutions. Moreover, this study investigated the error of this numerical model and accomplished further research on demonstrating the conditions to meet the stability of the model.

Synergistic Etching and Hydrogen Bonding-Induced Self-Assembly of MXene/MOF Hybrid Aerogel for Flexible Room-Temperature Gas Sensing.

Limited by insufficient active sites and restricted mechanical strength, designing reliable and wearable gas sensors with high activity and ductility remains a challenge for detecting hazardous gases. In this work, a thermally induced and solvent-assisted oxyanion etching strategy was implemented for selective pore opening in a rigid microporous Cu-based metal-organic framework (referred to as CuM). A conductive CuM/MXene aerogel was then self-assembled through cooperative hydrogen bonding interactions between the carbonyl oxygen atom in PVP grafted on the surface of defect-rich Cu-BTC and the surface functional hydroxyl group on MXene. A flexible NO2 sensing performance using the CuM/MXene aerogel hybridized sodium alginate hydrogel is finally achieved, demonstrating extraordinary sensitivity (S = 52.47 toward 50 ppm of NO2), good selectivity, and rapid response/recovery time (0.9/4.5 s) at room temperature. Compared with commercial sensors, the relative error is less than 7.7%, thereby exhibiting significant potential for application in monitoring toxic and harmful gases. This work not only provides insights for guiding rational synthesis of ideal structure models from MOF composites but also inspires the development of high-performance flexible gas sensors for potential multiscenario applications.

Optimal Dosage and Session Structure of Mindfulness-Based Programming for Youth Across Developmental Periods: Delphi Approach Outcomes

Purpose Research of mindfulness-based programming/interventions (MBP) for youth has proliferated in recent years; however, heterogeneity of MBP for youth impede determination of optimal programmatic structure across developmental periods. Design/Approach/Methods Expert MBP scientists and instructors were iteratively surveyed using the Delphi method to assess optimal MBP session structure across developmental periods. Findings Survey Round 1 defined the participants’ perspective of ideal structure across early childhood, middle childhood, and adolescence. In Survey Rounds 2 and 3, participants considered the preceding Round's results (means and SDs) and indicated what they believed was the ideal structure of a single MBP class. Final results following the Round 3 survey indicated that MBP session period should be progressively longer relative to the developmental time period (early childhood mean = 20.0 min; middle childhood mean = 34.5 min; adolescence mean = 50.0 min); that roughly half of a youth MBP session should be dedicated to mindfulness practice; and that progressively more time should be allocated to didactic instruction and discussion, relative to mindfulness practice, as youth become older. Originality/Value These findings are the first to report expert feedback on the ideal structure of a youth MBP session, and results have significant implications for future youth MBP evaluation, implementation, and curriculum development.

Charge transfer effects in (HfNbTiVZr)C—Shown by ab initio calculations and X‐ray photoelectron spectroscopy

AbstractConsidering charge transfer effects and the variability of the bonding between elements with different electronegativity opens up a deeper understanding of the electronic structure and as a result many of the properties in high entropy‐related materials. This study investigates the importance of the diverse bonding and chemical environments when discussing multicomponent carbide materials. A combination of ab initio calculations and X‐ray photoelectron spectroscopy (XPS) was used to investigate the electronic structure of multicomponent thin films based on the (HfNbTiVZr)C system. The charge transfer was quantified theoretically using relaxed and nonrelaxed multicomponent as well as binary carbide reference structures, employing a fixed sphere model. High‐resolution XPS spectra from (HfNbTiVZr)C magnetron‐sputtered thin films displayed core‐level binding energy shifts and broadening effects as a result of the complex chemical environment. Charge transfer effects and a changed electronic structure in the multicomponent material, compared with the reference binary carbides, are observed both experimentally and in the density functional theory (DFT) simulations. The observed effects loosely follow electronegativity considerations, leading to a deviation from an ideal solid solution structure assuming nondistinguishable chemically equivalent environments.

An accurate and efficient method for calculating surface waves in one-dimensional ideal and defective semi-infinite periodic structures

An accurate and efficient method for calculating surface waves in one-dimensional ideal and defective semi-infinite periodic structures

Synthesized Cs-rich Cs0.7FA0.3PbI2Br perovskite film by two-dimensional to three-dimensional phase transition

Stability of perovskite is the main limitation of the commercialization of perovskite solar cells. Recent studies have shown that FA-Cs perovskites are expected to achieve ideal crystal structures with outstanding stability when FA content is 30 %. And its bandgap can be adjusted to 1.8 eV, making it suitable for a top battery in the tandem cell. However, when the content of Cs ions in the component exceeds 30 %, phase separation occurs. In this study, a Cs-rich Cs0.7FA0.3PbI2Br perovskite film was synthesized by using a 2D to 3D phase transition method. Through the high orientation of the 2D CsPbI3-FAI alloy-like phase and the anisotropic volatilization of FA, a well-oriented α-Cs0.7FA0.3PbI2Br perovskite phase is obtained. The α-Cs0.7FA0.3PbI2Br shows excellent thermal and UV stability and improved humidity stability. Meanwhile, the fabricated Cs0.7FA0.3PbI2Br perovskite solar cell achieved a competitive power conversion efficiency of 14.87 % successfully breaking the world record for this perovskite system. This further advances the research progress of Cs-rich perovskites in highly efficient and stable solar cells.

A novel maternal thyroid disease prediction using multi-scale vision transformer architecture with improved linguistic hedges neural-fuzzy classifier.

Early pregnancy thyroid function assessment in mothers is covered. The benefits of using load-specific reference ranges are well-established. We pondered whether the categorization of maternal thyroid function would change if multiple blood samples obtained early in pregnancy were used. Even though binary classification is a common goal of current disease diagnosis techniques, the data sets are small, and the outcomes are not validated. Most current approaches concentrate on model optimization, focusing less on feature engineering. The suggested method can predict increased protein binding, non-thyroid syndrome (NTIS) (simultaneous non-thyroid disease), autoimmune thyroiditis (compensated hypothyroidism), and Hashimoto's thyroiditis (primary hypothyroidism). In this paper, we develop an automatic thyroid nodule classification system using a multi-scale vision transformer and image enhancement. Graph equalization is the chosen technique for image enhancement, and in our experiments, we used neural networks with four-layer network nodes. This work presents an enhanced linguistic coverage neuro-fuzzy classifier with chosen features for thyroid disease feature selection diagnosis. The training procedure is optimized, and a multi-scale vision transformer network is employed. Each hop connection in Dense Net now has trainable weight parameters, altering the architecture. Images of thyroid nodules from 508 patients make up the data set for this article. Sets of 80% training and 20% validation and 70% training and 30% validation are created from the data. Simultaneously, we take into account how the number of training iterations, network structure, activation function of network nodes, and other factors affect the classification outcomes. According to the experimental results, the best number of training iterations is 500, the logistic function is the best activation function, and the ideal network structure is 2500-40-2-1. K-fold validation and performance comparison with previous research validate the suggested methodology's enhanced effectiveness.

On a class of constacyclic codes of length 4ps over 𝔽pm[u] 〈u3〉

Let [Formula: see text] be a prime such that [Formula: see text], where [Formula: see text] is a positive integer. For any nonzero element [Formula: see text] of [Formula: see text], we determine the algebraic structure of all [Formula: see text]-constacyclic codes of length [Formula: see text] over the finite commutative chain ring [Formula: see text], where [Formula: see text] and [Formula: see text] is a positive integer. If the unit [Formula: see text] is a square, [Formula: see text], each [Formula: see text]-constacyclic code of length [Formula: see text] is expressed as a direct sum of an [Formula: see text]-constacyclic code and an [Formula: see text]- constacyclic code of length [Formula: see text]. In the main case that the unit [Formula: see text] is not a square, it is shown that any nonzero polynomial of degree at most [Formula: see text] over [Formula: see text] is invertible in the ambient ring [Formula: see text]. It is also proven that the ambient ring [Formula: see text] is a local ring with the unique maximal ideal [Formula: see text], where [Formula: see text]. Such [Formula: see text]-constacyclic codes are then classified into eight distinct types of ideals, and the detailed structures of ideals in each type are provided. Among other results, the number of codewords, and the dual of each [Formula: see text]-constacyclic code are obtained. The non-existence of self-dual and isodual [Formula: see text]-constacyclic codes of length [Formula: see text] over [Formula: see text], when the unit [Formula: see text] is not a square, is likewise proved.

Shallow-level defect passivation by 6H perovskite polytype for highly efficient and stable perovskite solar cells

The power conversion efficiency of perovskite solar cells continues to increase. However, defects in perovskite materials are detrimental to their carrier dynamics and structural stability, ultimately limiting the photovoltaic characteristics and stability of perovskite solar cells. Herein, we report that 6H polytype perovskite effectively engineers defects at the interface with cubic polytype FAPbI3, which facilitates radiative recombination and improves the stability of the polycrystalline film. We particularly show the detrimental effects of shallow-level defect that originates from the formation of the most dominant iodide vacancy (VI+) in FAPbI3. Furthermore, additional surface passivation on top of the hetero-polytypic perovskite film results in an ultra-long carrier lifetime exceeding 18 μs, affords power conversion efficiencies of 24.13% for perovskite solar cells, 21.92% (certified power conversion efficiency: 21.44%) for a module, and long-term stability. The hetero-polytypic perovskite configuration may be considered as close to the ideal polycrystalline structure in terms of charge carrier dynamics and stability.

Unprecedented Strength Enhancement Observed in Interpenetrating Phase Composites of Aperiodic Lattice Metamaterials

AbstractSimultaneous high strength and high toughness are highly sought‐after in lattice metamaterials, but these properties are typically mutually exclusive. To overcome this challenge, the development of interpenetrating phase composite (IPC), which incorporates a net matrix infill into the lattice, has shown great potential in overcoming these constraints and is thus of continuous practical interest. In this work, a novel aperiodic monotile truss lattice and polymer IPC that exhibit unprecedented enhancement in both strength and toughness are reported. Specifically, the aperiodic unit cell is inspired by Einstein's monotile, a single space‐filling shape where the cell orientation never repeats. The IPCs are achieved through 3D‐printed Ti‐6Al‐4V truss lattices and epoxy infiltration. The highest gain in compressive strength reveals an impressive 246.61% increase, significantly exceeding the “1 + 1 > 2” idealization typically associated with strength in IPC metamaterials. Furthermore, a high specific energy absorption of 46.2 J g−1 demonstrates superior toughness. The underlying mechanisms, including damage sequences, two‐phase interactions, and geometric effects between truss and epoxy, are fully elucidated. Overall, this work reports unprecedented enhancement in IPC's properties and demonstrates the potential of utilizing idealized structures to achieve an optimal combination of strength and toughness in mechanical metamaterials.

Elastodynamic shape derivative: focus on the sampling of a circular distribution

The detection and quantification of defects plays a crucial role in several industries. Assessing the severity enables to schedule maintenance appropriately, optimizing costs and reducing risks. Guided elastic waves are particularly suitable for Structural Health Monitoring applications on thin structures thanks to their long range and high sensitivity. Guided wave tomography, based on an acoustic propagation hypothesis, has been studied over the last decade to quantitatively image defects in waveguides. The acoustic approximation of this family of methods allows fast computation and good estimation of defects for simple geometries such as plates or pipes. However, this hypothesis induces that a single guided mode is considered, without mode conversion, which limits its use to defects larger than two wavelengths in structures close to ideal waveguides. Hence the need of new imaging algorithms for smaller defects in less ideal structures such as pipes with welded supports. We present here an adaptation of the shape derivative method to ultrasounds in order to reconstruct surface defect on structures with complex geometries. The physical model used is the full elastodynamic problem. It allows taking into account all physical phenomena occuring during wave propagation. Iterative methods such as shape derivative are well known to give precise results but at a high computational cost as the method needs to solve the full elastodynamic problem at each iteration, and a sensitivity to local minima, which may prevent convergence toward the true defect. To suppress these two drawbacks, a spectral finite element method is used to reduce the computation and memory costs. The result of acoustic guided wave tomography is also used as a first guess to reduce the number of iterations and the sensitivity to local minima. After explaining the principle of the shape derivative, validations on simulated and experimental data will be presented in this talk.

Impact of Vascular Access Teams on Central Line Associated Bloodstream Infections

Background: During the COVID-19 pandemic, rates of central line bloodstream infections (CLABSI) increased nationally. Studies pre-pandemic showed improved CLABSI rates with implementation of a standardized vascular access team (VAT).[PL1] [PL2] [mi3] Varying VAT resources and coverage existed in our 10 acute care facilities (ACF) prior to and during the pandemic. VAT scope also varied in 1) process for line selection during initial placement, 2) ability to place a peripherally inserted central catheter (PICC), midline or ultrasound-guided peripheral IV in patients with difficult vascular access, 3) ownership of daily assessment of central line (CL) necessity, and 4) routine CL dressing changes. We aimed to define and implement the ideal VAT structure and evaluate the impact on CLABSI standardized infection ratios (SIR) and rates prior to and during the pandemic. Methods: A multidisciplinary workgroup including representatives from nursing, infection prevention, and vascular access was formed to understand the current state of VAT responsibilities across all ACFs. The group identified key responsibilities a VAT should conduct to aid in CLABSI prevention. Complete VAT coverage[mi4] was defined as the ability to conduct the identified responsibilities daily. We compared the SIR and CLABSI rates between hospitals who had complete VAT (CVAT) coverage to hospitals with incomplete VAT (IVAT) coverage. Given this work occurred during the pandemic, we further stratified our analysis based on a time frame prior to the pandemic (1/2015 – 12/2019) and intra-pandemic (1/2020 - 12/2022). Results: The multidisciplinary team identified 6 key components of complete VAT coverage: Assessment for appropriate line selection prior to insertion, ability to insert PICC and midlines, daily CL and midline care and maintenance assessments, daily assessment of necessity for CL, and weekly dressing changes for CL and midlines[NA5] . A cross walk of VAT scope (Figure 1) was performed in October 2022 which revealed two facilities (A and E) which met CVAT criteria. Pre-pandemic, while IVAT CLABSI rates and SIR were higher than in CVAT units, the difference was not statistically significant. During the pandemic, however, CLABSI rates and SIR were 40-50% higher in IVAT compared to CVAT facilities (Incident Rate Ratio 1.5, 95% CI 1.1-2.0 and SIR Relative Ratio 1.4, 95% CI1.1-1.9 respectively) (Table 1). Conclusions: CLABSI rates were lower in facilities with complete VAT coverage prior to and during the COVID-19 pandemic suggesting a highly functioning VAT can aid in preventing CLABSIs, especially when a healthcare system is stressed and resources are limited.

Thermal conductivity of BaZrO3 and KTaO3 single crystals

BaZrO3 and KTaO3 are two rare examples of perovskite oxides that retain the ideal cubic structure down to the lowest temperature. In this paper, we report thermal conductivity (κ) between 300 and 773 K on single crystals of these compounds. For BaZrO3, the κ of 7.5 Wm−1K−1 at 300 K is ∼40% larger than the previously reported polycrystalline values. For KTaO3, our value of 13.1 Wm−1K−1 at 300 K clarifies the sources of error in some of the previously reported data. These results underscore the importance of high-quality experimental data in benchmarking the accuracy of advanced first-principles κ calculations.

Evaluation of Point Group Symmetry in Lanthanide(III) Complexes: A New Implementation of a Continuous Symmetry Operation Measure with Autonomous Assignment of the Principal Axis.

The structure of molecular systems dictates the physical properties, and symmetry is the determining factor for all electronic properties. This makes group theory a powerful tool in quantum mechanics to compute molecular properties. For inorganic compounds, the coordination geometry has been estimated as idealized polyhedra with high symmetry, which, through ligand field theory, provides predictive capabilities. However, real samples rarely have ideal symmetry, and although continuous shape measures (CShM) can be used to evaluate deviation from an ideal reference structure σideal, this often fails for lanthanide(III) complexes with high coordination numbers, no obvious choice of principal axes, and no obvious reference structure. In lanthanide complexes, the unique electronic structures and associated properties are intricately tied to the symmetry around the lanthanide center. Therefore, robust methodologies to evaluate and estimate point group symmetry are instrumental for building structure-property relationships. Here, we have demonstrated an algorithmic approach that orients a molecular structure Q in the best possible way to the symmetry axis of any given point group G and computes a deviation from the ideal symmetry σsym(G,Q). This approach does not compute the deviation from an ideal reference system, but the intrinsic deviation in the structure induced by symmetry operations. If the structure contains the symmetry operation, there is no deviation and σsym(G,Q) = 0. The σsym deviation is generated from all of the symmetry operation ÔS in a point group G using the most correct orientation of the sample structure in each group G. The best orientation is found by an algorithm that minimizes the orientation of the structure with respect to G. To demonstrate the methodology, we have investigated the structure and symmetry of 8- and 9-coordinated lanthanide(III) aqua complexes and correlated the luminescence from 3 europium(III) crystals to their actual symmetry. To document the methodology, the approach has been tested on 26 molecules with different symmetries. It was concluded that the method is robust and fully autonomous.

Coordination networks in accordion-like copper based metal–organic frameworks facilitate efficient catalytic strategies in high performance lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are attractive for electric vehicles due to their high theoretical capacity and low cost. However, they severely suffer from the “shuttle effect”, which causes capacity fading and self-discharge. Metal-organic frameworks (MOFs) have been proposed as an effective sulfur-loaded matrix material to mitigate this problem via providing sufficient catalytic sites for accelerating sulfur redox reactions (SRR). In this study, a novel accordion-like copper-based coordination network matrix material is constructed with pyridine-2,4-dicarboxylic acid as the ligands, which the layered structure can effectively adsorbs LiPSs, thereby avoiding the loss of reactive active material. Besides that, the coordination network can reduce the activation energy barrier of Li2S decomposition and the redox conversion rate between S8 and Li2S. It is revealed that the materials with ideal layered structure can facilitate SRR via providing Lewis acid-base interactions between Cu atoms and LiPSs. Electrochemical results in a high discharge capacity of 751.25 mAh·g−1 at a high current density of 2C has been achieved and when returns to 0.2C after 60 cycles, it can recover a high reversible capacity of 1093.63 mAh·g−1. It demonstrates that coordination network materials with ideal layered structure can be as a promising strategy for overcoming the challenges of LSBs and expanding their potential applications.

Ideal two-dimensional electronic structure in bulk lead titanate for superior thermoelectrics

An ideal two-dimensional (2D) electronic structure is revealed in n-type tetragonal perovskite PbTiO3 through first-principle calculations. This opens exciting prospects for its applications in thermal-to-electrical energy conversion. The electronic structure is regarded as ideally 2D when it is highly dispersive only along two axes, while along the remaining axis, it is nearly non-dispersive with a bandwidth smaller than 1 meV – insignificant when compared to thermal energy above room temperature (i.e., kBT ≥ 25.9 meV). As a basis for comparison, the electronic structure of the cubic perovskite SrTiO3 is calculated. It is nonideal 2D with the bandwidth along the less dispersive axis larger than the thermal energy. The ideal 2D electronic structure in PbTiO3 leads to a 2D-like density of states, resembling a step function around the conduction minimum while for SrTiO3, the density of states remains 3D-like with a square-root energy dependence. Consequently, n-type PbTiO3 exhibits superior effective band degeneracy within the Fermi window compared to SrTiO3, even though PbTiO3 is nondegenerate at the conduction band minimum, while cubic SrTiO3 is three-fold degenerate. This demonstrates the important role of the ideality in the 2D electronic structure. The ab-initio results demonstrate the potential of PbTiO3 as a promising thermoelectric material.

A proportional topology optimization method with level-set description and evolutionary strategy

In this work, we propose a proportional topology optimization method with a level-set description and evolutionary strategy (PTO-LSES). A level-set function (LSF) evolution scheme based on the nodal compliance proportion is presented and utilized in the new method. Furthermore, a compliance proportion filtering technique, a regularization scheme, and a material interpolation model with penalty are also used in the proposed method. To determine the effectiveness and superiority of the PTO-LSES method, both the 2D (cantilever beam) and 3D (cantilever and half-MBB beams) numerical examples solving the compliance minimization problem, in contrast to the conventional solid isotropic material with penalization (SIMP) and the original proportional topology optimization (PTO) methods, were tested. In addition, we discuss the impact of compliance proportion filtering and regularization schemes on the new method using 2D half-MBB and cantilever beams. The results showed that compared to the SIMP and PTO methods, the PTO-LSES method offered great advantages via the ability to acquire better objective function (compliance) values and more ideal topology structures with smooth and clear boundaries when subjected to specific conditions. Furthermore, applying the compliance pro-portion filtering technique or regularization scheme to the PTO-LSES method enhanced the performance of the new method in many ways.