Configuration Variables Research Articles

Development and growth of fasciae in and around the esophageal hiatus: a histological study using human fetuses.

An entire fascial configuration at the esophageal hiatus might not be demonstrated histologically. According to observations of human fetus histology, the aim of this study was to consider which factor is likely to make the individual variation in adults. We observed frontal histological sections containing the esophageal hiatus from 12 midterm fetuses at 12-16 weeks (crown-rump length: CRL, 85-137mm) and 10 near-term fetuses at 26-30 weeks (CRL, 214-250mm). At midterm, the transversalis fascia covering the diaphragm turned upward to join the adventitia of the left aspect of the esophagus: thus, the upper leaflet of the phreno-esophageal membrane was established first. A connection between the adventitia and endothoracic fascia (i.e., the upper leaflet of the PEM) was deleyed in the right. At near-term, both the transversalis and endothoracic fasciae often joined the adventitia in the left side but not in the right side. Therefore, fascial development advanced in the left side as well as the inferior side of the hiatus. The foregut-midgut junction, suggested with cytokeratin 5/6 immunostaining, was located in the hiatus. Development and growth of the phreno-esophageal membrane showed left/right and superior/inferior differences. The transiently-appeared pleural recess, the upward protruding right crus of diaphragm and, the right liver and adrenal extending upward seemed to disturb the fascial connection to the adventitia in the right and/or superior side. Individual variations in the fascial configuration at the hiatus might occur due to the site-dependent delay of the establishment of structures.

Regulated Charge Transfer in Donor-Acceptor Metal-Organic Frameworks for Highly-Sensitive Photodetectors.

In photo-induced charge separation, organic thin films with donor and acceptor chromophores are vital for uses such as artificial photosynthesis and photodetection. The main challenges include optimizing charge separation efficiency and identifying the ideal acceptor/donor ratio. Achieving this is difficult due to the variability in molecular configurations within these typically amorphous organic aggregates. Metal-organic frameworks (MOFs) provide a structured solution by enabling systematic design of donor/acceptor blends with adjustable ratios within a crystalline lattice. We demonstrate this approach by incorporating donor and acceptor naphthalenediimide (NDI) chromophores as linkers in a highly oriented, monolithic MOF thin film. By adjusting the NDI acceptor linker concentration during the layer-by-layer assembly of surface-anchored MOF thin films (SURMOFs), we significantly enhanced charge separation efficiency. Surprisingly, the optimum acceptor concentration was only 3%, achieving a forty-fold increase in photodetection efficiency compared to baseline NDI donor-based SURMOFs. This unexpected behaviour was clarified through theoretical analysis enabled by the well-defined crystalline structure of the SURMOFs. Using density functional theory and kinetic Monte Carlo simulations, we identified two opposing effects from acceptors: the positive effect of suppressing undesirable charge carrier recombination is offset at high concentrations by a reduction in charge-carrier mobility.

Peripheral versus central cannulation of VA-ECMO for primary graft dysfunction after heart transplantation: A systematic review and meta-analysis

Severe primary graft dysfunction (PGD) after heart transplantation (HT) is a major cause of death and requires veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Given the wide between-center variability in cannula configuration, we conducted a systematic review and metanalysis including studies of adult HT recipients who required VA-ECMO for PGD to determine whether a peripheral or central configuration was associated with higher mortality. The primary endpoints were short-term and one-year mortality. Secondary endpoints were VA-ECMO-related complications. Overall, we included 16 studies comprising 874 patients from 33 centers. Using a random effects model, peripheral cannulation was associated with a non-significant reduction in short-term mortality (OR=0.73, 95%CI=0.41–1.28, I2=55.8%) and a significant reduction in one-year mortality (OR=0.60, 95%CI=0.37–0.97, I2=35.9%). Peripheral cannulation decreased risk of bleeding but increased risk of limb ischemia and infection, with similar rates of stroke and need for renal replacement therapy. Overall, certainty of evidence was low.

Estimation of the displacement of soil nailing vertical face structures intended for building undergrounds

ABSTRACT This study proposes a methodology for estimating horizontal displacements in vertical face soil-nailing structures in urban areas, analyzing 20 projects in São Paulo, Brazil. To minimize displacements, post-grouting sectorized injections through polyethylene tubes was used, a methodology routinely adopted in Brazil which gives the soil mass a significant increase in strength and stiffness.To study the effect of the sectorized injections on soil treatment, a three-dimensional computational model using Plaxis 3D software and calibrated through back-analysis according to the displacements of the structures. Additionally, 11 models were tested with variations in nail length, mesh configuration, and geotechnical parameters, considering injection effects. The study provides design and execution guidelines to optimize this technique. Equations derived from the study predict horizontal displacements, which will be used to assess the technical feasibility of the projects in advance and, when they are being executed, to provide performance control within a more precise and realistic margin.

Machine learning and deep learning models for the diagnosis of apical periodontitis: a scoping review.

To assess the existing literature on the use of machine learning (ML) and deep learning (DL) models for diagnosing apical periodontitis (AP) in humans. A scoping review was conducted following the Arksey and O'Malley framework. The PubMed, SCOPUS, and Web of Science databases were searched, focusing on articles using ML/DL approaches for AP diagnosis. No restrictions were applied. Two independent reviewers screened publications and charted data in predefined Excel tables for analysis. Nineteen publications focused on diagnosing AP by identifying periapical radiolucent lesions (PRLs) in dental radiographs were included. The average sensitivity and specificity for reviewed models were 83% and 90%, respectively. Only three studies explored the direct impact of artificial intelligence (AI) assistance on clinicians' diagnostic performance. Both consistently showed improved sensitivity without compromising specificity. Significant variability in dataset sizes, labeling techniques, and algorithm configurations was noticed. Findings affirm AI models' effectiveness and transformative potential in diagnosing AP by improving the accurate detection of periapical radiolucencies using dental radiographs. However, the lack of standardized reporting on crucial aspects of methodology and performance metrics prevents establishing a definitive diagnostic approach using AI. Further studies are needed to expand AI applications in AP diagnosis beyond radiographic analysis. AI can potentially improve diagnostic accuracy in AP diagnosis by enhancing the sensitivity of PRL detection in dental radiographs without compromising specificity.

Root and Canal Morphology of Maxillary Incisors Teeth in a Sample of Yemeni Population Using Two Classification Systems: A CBCT Study

Objective: To determine the root and canal morphology of permanent maxillary central and lateral incisors in a sample of Yemeni population using cone-beam computed tomography (CBCT). Materials and Methods: A retrospective CBCT analysis of 400 maxillary anterior teeth from a Yemeni adults (18-50 years) was conducted. Image evaluation in sagittal, axial, and coronal planes using Ez3D-i software assessed root number, canal orifice number, canal number, and canal configuration based on Vertucci's and Ahmed's classifications. Descriptive statistics and Chi-square test were employed (p < 0.05). Results: All incisors exhibited a single root and canal with a single orifice. The predominant canal configuration was Type 1 according to both Vertucci's (93.5%) and Ahmed's (93.8%) classifications. Type 5 (bifurcation at the apex) was observed in 6.25% (Vertucci) and 6.0% (Ahmed) of cases, while Type 3 (canal division and reunion) was rare (0.25% Vertucci, 0.2% Ahmed). Conclusion: Permanent maxillary central and lateral incisors in the Yemeni population primarily demonstrate a single root and canal. Although variations in canal configuration exist, they are infrequent.

Global R-wave peak time for diagnosis of left bundle branch capture

BackgroundQRS axis deviation and rS configuration in V6 affect the ability of V6 R-wave peak time (RWPT) criterion to discriminate capture type during left bundle branch area pacing (LBBAP). ObjectiveWe hypothesized that combining RWPTs from lateral leads: I, aVL, V5, and V6 may better reflect left ventricular activation time and that such a global RWPT may be insensitive to changes in QRS configuration. MethodsThe analysis included 519 electrocardiograms (ECGs) with nonselective left bundle branch pacing (nsLBBP) and 176 ECGs with left ventricular septal pacing (LVSP). Optimal RWPT cutoffs and area under the receiver operating curve (AUC) were determined for each lead and combinations of leads, to find the best RWPT criterion for discriminating nsLBBP from LVSP. Values were reported separately for healthy and diseased left conduction system groups. ResultsThe highest AUC of 97.1/89.2% was obtained for the global RWPT, which combined leads I and V6. The AUC for single-lead RWPT, was highest for lead I, followed by V6, V5, and aVL with AUC of 95.1/87.4%, 93.6/87.1%, 93.0/86.5%, and 84.8/74.6%, respectively. The global RWPT criterion was not affected by variations in QRS configuration, as V6 and I RWPTs often showed opposite responses to changes in axis. In contrast, all single-lead RWPT criteria were sensitive to axis deviation and QRS configuration. Diagnostically optimal RWPT cutoffs for global RWPT and lead I RWPT were 162.5/187.5 ms, and 81.5/90.5 ms, respectively. ConclusionThe global RWPT criterion allows a more accurate diagnosis of LBBAP capture type independent of QRS configuration and axis.

Visual fields, foraging and collision vulnerability in gulls (Laridae)

Wide variation in visual field configuration has been recorded among avian species and it is hypothesized that this variation is driven primarily by foraging ecology and predator detection. It has also been shown that visual field configurations can render some species more vulnerable to collisions with human artefacts that extend into open airspace, such as power lines and wind turbines. Visual fields have three main components: the monocular fields describe the extent of the world seen by each eye, the binocular field describes the region where the monocular fields overlap, and the blind area describes the region in which no vision is provided. Among birds, the topography of the binocular field, and the extent and position of the blind area, show considerable interspecific variation. Although Laridae (gulls, terns, skimmers) are a large and cosmopolitan taxon, visual field characteristics of only one species, Black Skimmer Rynchops niger, have been determined. However, skimmers are distinct from other Laridae species because they use a specialized foraging technique based upon tactile cues. We determined visual fields in three species of gulls (European Herring Gulls Larus argentatus, Lesser Black‐backed Gulls Larus fuscus, Black‐legged Kittiwakes Rissa tridactyla), and found that they show the key characteristics associated with visually guided foraging. However, the binocular field does not extend through the full height of the frontal field. This results in a blind sector, which can project in the direction of flight when gulls pitch their heads sufficiently far forwards to visually search the surface below. This could render gulls vulnerable to collisions with anthropogenic structures (power lines, wind turbines) that extend into the open airspace. Photographs show that gulls in level flight do pitch their heads forward sufficiently to render them almost blind in the direction of travel, and further work on the head positions adopted by gulls in flight are recommended. The visual field of skimmers differs markedly from those of gulls. Their binocular field topography is interpreted as functioning in the control of bill position when skimming (flying just above the water surface with the elongated, blade‐like, rhamphotheca of the mandible extending through the water surface). Skimmers also have a blind area, which projects forwards in the direction of travel when skimming. This can be associated with the vulnerability of skimmers to collisions with objects that extend just above the water surface.

Exploration of Solid Phase Peptoid Synthesis for the Design of Trifunctional Hapten-Lipid-TLR7/8 Agonist Antibody-Recruiting Oligomers That Combine Innate Effector with Innate Activation Function.

The strategic engagement of innate immunity is a promising avenue for cancer treatment. Antibody-recruiting molecules (ARMs) direct endogenous antibodies to target tumor sites, eliciting innate immune effector killing responses. In this study, we report the synthesis of ARMs by employing solid-phase peptoid synthesis to construct three libraries of antibody-recruiting oligomers. Using dinitrophenyl (DNP) as a model hapten and alkyl lipid chains for cell surface anchoring, we tailored oligomers with variations in valency and spatial configuration. Among these, an oligomer design featuring DNP connected to the oligomer backbone through an extended PEG linker and flanked by two lipid motifs emerged as the most effective in antibody recruitment in vitro. This oligomer was further functionalized to include an imidazoquinoline, creating a trifunctional hapten-lipid-TLR7/8 agonist oligomer, and a parallel variant was conjugated with rhodamine, resulting in a trifunctional hapten-lipid-dye oligomer. Upon intratumorally administration in a murine model, these oligomers induced localized immune activation within tumors. Subsequent ex vivo analysis of single-cell suspensions from excised tumors confirmed the enhanced binding of anti-DNP antibodies. These findings underscore the potential of custom-designed ARMs in orchestrating precise immune-mediated tumor targeting and highlight the adaptability of solid-phase synthesis in oligomer design for the design of multifunctional antibody recruiting molecules.

A Click Chemistry Strategy Toward Spin-Polarized Transition-Metal Single Site Catalysts for Dynamic Probing of Sulfur Redox Electrocatalysis.

Catalytic conversion of lithium polysulfides (LiPSs) is a crucial approach to enhance the redox kinetics and suppress the shuttle effect in lithium-sulfur (Li-S) batteries. However, the roles of a typical heterogenous catalyst cannot be easily identified due to its structural complexity. Compared with the distinct sites of single atom catalysts (SACs), each active site of single site catalysts (SSCs) is identical and uniform in their spatial energy, binding mode, and coordination sphere, etc. Benefiting from the well-defined structure, iron phthalocyanine (FePc) is covalently clicked onto CuO nanosheet to prepare low spin-state Fe SSCs as the model catalyst for Li-S electrochemistry. The periodic polarizability evolution of Fe-N bonding is probed during sulfur redox reaction by in situ Raman spectra. Theoretical analysis shows the decreased d-band center gap of Fe (Δd) and delocalization of dxz/dyz after the axial click confinement. Consequently, Li-S batteries with Fe SSCs exhibit a capacity decay rate of 0.029% per cycle at 2 C. The universality of this methodological approach is demonstrated by a series of M SSCs (M = Mn, Co, and Ni) with similar variation of electronic configuration. This work provides guidance for the design of efficient electrocatalysis in Li-S batteries.

Micro–Computed Tomographic Analysis of Radicular Dentin Thickness in Mandibular Second Molars Across Diverse Anatomic Root Variations: Identifying Potential Danger Zones

IntroductionThis study aimed to investigate radicular dentin thicknesses in mandibular second molars (MSMs), considering variations in root configuration and the morphology of the pulp chamber floor (PCF). The types of radicular grooves and potential danger zones were also identified. MethodsA total of 149 MSMs were scanned with micro–computed tomographic imaging and classified into 4 groups according to root fusion and PCF morphology as follows: (1) 45 with fused roots and C-shaped PCFs, (2) 45 with fused roots and non–C-shaped PCFs, (3) 14 with a single canal, and (4) 45 with separated roots. The first 2 groups were subdivided into Ω-shaped, U-shaped, and V-shaped radicular groove subgroups. Measurements included minimum and mean dentin thickness from the start of the radicular groove or root bifurcation extending 5 mm apically, the ratio of outer to inner dentin thickness, and the distribution of dentin thickness. ResultsΩ-shaped and U-shaped subgroups showed significant thinner minimum inner wall thickness than V-shaped subgroups at 2–5 mm from the starting point of the radicular groove in both C-shaped and non–C-shaped pulp floor categories (P < .05). The mesial roots of separated rooted MSMs showed significant thinner dentin than a non–C-shaped floor regarding minimum and mean inner thickness and mean outer thickness (P < .05). Teeth with a single canal had significantly thicker walls compared with the other 3 groups. ConclusionsIn MSMs, caution must be exercised, especially in the presence of Ω-shaped and U-shaped grooves in C-shaped roots and around the root furcation of separated roots.

Bioelectrical impedance vector analysis and track and field jump performance across different specialties: Sex differences and electrode configuration.

The assessment of athletic performance using non-invasive methods has been a significant focus in research aimed at measuring physiological parameters. This study explores the application of bioelectrical impedance vector analysis (BIVA) among track and field athletes, with a focus on sex differences, electrode configuration, and the correlation between BIVA parameters and jump performances. This cross-sectional study involved 61 Italian track and field athletes: 31 females and 30 males (age: 21.4 ± 3.8; 21.1 ± 2.6 years; stature: 166.1 ± 6.1; 180.1 ± 5.0 cm; body mass: 57.4 ± 9.7; 72.5 ± 10.5 kg, respectively). Anthropometric measurements, bioelectrical impedance analysis, and athletic jump performance were conducted. The RXc graph, two-sample Hotelling's T2 test for BIVA, and one-way ANOVA for specialty comparisons were employed. Pearson and Spearman's tests evaluated the correlations between BIVA parameters and jump performance. Differences in bioimpedance values were observed between athlete groups. Lateral asymmetries were more pronounced in females. Correlations between BIVA and jump performance also varied by sex and electrode configuration, ranging from r = -0.072, p = 0.699-r = 0.555, p = 0.001 in females, and from r = 0.204, p = 0.281-r = 0.691, p = 0.001 in males. This study highlights the utility of BIVA in providing rapid and non-invasive assessments of body composition and its relationship with jump performance, considering variations in athlete sex and electrode configuration.

Concurrent topology optimization of sandwich structures with multi-configuration and variable-diameter lattice infill

The superior stiffness-to-weight and strength-to-weight mechanical advantages of sandwich structures can be fully exploited through concurrent design of entire topology, infill configuration and density, where the high-performance yet complicated structure can be fabricated through additive manufacturing. However, the emerging design challenges are concurrent design updating related to sandwich topology, infill configuration and density, which is a design problem with continuous and discrete variables mathematically. In this paper, a concurrent topology optimization is proposed for sandwich structures with multi-configuration and variable-diameter lattice infill. Three design variable fields are employed to describe the fundamental topology considering sandwich structural topology, infill configuration and density simultaneously. Corresponding material interpolation model is developed by combining DSP-based shell-infill description and multi-response latent-variable surrogate model based effective material property calculation. Two-stage design model is formulated as a rough design model considering all design variables followed by a refined design model with only infill density variables, which is developed to strictly satisfy the material allowance constraint due to the mapping between discrete infill configuration variables and continuous latent configuration variables. Corresponding sensitivities of compliance and constraint with respect to the structural topology, infill configuration and density variables are derived, and the method of moving asymptotes (MMA) is employed to solve the design model efficiently. Several numerical examples are presented to systematically demonstrate the effectiveness of the proposed approach.

Anatomical study of variations in the configurations of the circle of Willis in relation to age, sex, and diameters of the components.

The circle of Willis (COW) refers to the anastomotic arterial network found on the brain base, tasked with provision of collateral circulation aimed at prevention of ischemia. The COW is of immense clinical importance especially with regard to the assessment of neurovascular diseases. Individuals portray significant variations in the COW's anatomical configuration. The present study seeks to evaluate the existing anatomical variations of the COW and within the anterior and posterior segments of the COW. Thus, the study seeks to evaluate the different anatomical variations of the COW and its segments and components within the study population. To attain the set objectives, the present study has utilized the angiographic images for studying the COW variants in patients who underwent cerebral angiography during assessment of different types of cerebral anomalies and conditions. Therefore, this study used conventional angiography as an important tool in the evaluation of the different variations in the COW, and is most appropriate for evaluation of smaller anatomical variations owing to its perfect spatial resolution and portrayal of COW anatomy. The study findings indicated the existence between age and sex, and anatomical variations of the COW, particularly with regard to diameters of COW components like basilar artery (BA), P1, and internal carotid arterys (ICAs). Males had bigger BA, P1 and ICA diameters than females, while individuals aged below 40 years had bigger BA, A1, posterior communicating artery, and ICA diameters than those aged above 40 years.

Configuration of the early-mid Cenozoic extensional arc volcanism of the North Patagonian and the Southern Central Andes (33–44°S)

The late Eocene to earliest Miocene volcanic arc of the Southern Central Andes (33–40°S) and North Patagonian Andes (40–44°S) exhibits distinctive features that shed light on the dynamics of subduction-related volcanic activity in extensional tectonic settings. This period is particularly significant in the Andes, as it records the opening of forearc, intra-arc, and retroarc extensional basins, accompanied by high-volume volcanism, preceding the middle-late Miocene final major uplift phase of the Andes. This extensional event occurred in two phases, associated with changes in the geometry and dynamics of the subduction system: from oblique convergence at low rates during the late Eocene-early Oligocene to an orthogonal convergence at high rates during the late Oligocene-early Miocene. This study presents a compilation of field, petrographic, geochemical, and isotopic data from volcanic sequences in the North Patagonian Andes and the Southern Central Andes, aiming to analyze petrogenetic processes at different stages of arc evolution.During the late Eocene to early Oligocene, subduction-related volcanism occurred in a wide area from 100 to 300 km from the trench. In this period, magmatic arc rocks exhibit intermediate composition and a relatively homogeneous geochemical signature, transitional between tholeiitic and calc-alkaline series, with a marked subduction-related signature. These magmas originated from depleted mantle sources with high slab-derived fluid and sediment contributions and limited crustal interactions. In contrast, the late Oligocene to earliest Miocene volcanic activity, at the peak of the extensional regime, displays significant geochemical differences along the Andes. In the Southern Central Andes (33–40°S), volcanism displays compositions similar to those of the previous stage with varying influence from the subducting slab. In some sectors, magmas register the climax of the extensional conditions, whereas the youngest volcanic rocks towards the north (33–34°S) present evidence of the onset of contractional tectonics, demonstrated by the increased interaction of the magmas with a progressively thickened crust. In the North Patagonian Andes (40–44°S), subaerial and subaqueous arc-related lava flows are interbedded with marine deposits, indicating a rapid subsidence regime. These rocks exhibit geochemical features transitional from arc to E-MORB and even OIB compositions, which suggest a genesis primarily dominated by decompression melting of a heterogeneous mantle source. Above all, the contrasting nature of late Eocene-early Miocene arc products in the Southern Central and Patagonian Andes highlights that no single process can explain the changes in composition, distribution, and evolution of arc magmatism; rather, it is a combination of factors, including variations in subduction zone configuration and mantle dynamics and composition.

Supervisory Control for Dynamic Feature Configuration in Product Lines

In this paper a framework for engineering supervisory controllers for product lines with dynamic feature configuration is proposed. The variability in valid configurations is described by a feature model. Behavior of system components is achieved using (extended) finite automata and both behavioral and dynamic configuration constraints are expressed by means of requirements as is common in supervisory control theory. Supervisory controller synthesis is applied to compute a behavioral model in which the requirements are adhered to. For the challenges that arise in this setting, multiple solutions are discussed. The solutions are exemplified in the CIF toolset using a model of a coffee machine. A use case of the much larger Body Comfort System product line is performed to showcase feasibility for industrial-sized systems.

Stiffness optimization design of wheeled-legged rover integrating active and passive compliance capabilities

Compliance capability is one of the most important properties of suspension systems for rough-terrain robots. This imposes specific requirements on system stiffness design, which directly determines the platform's performance in response to external stimuli. To address the challenge of stiffness optimization design in active and passive compliant systems, this paper proposes a novel and practical method for optimizing stiffness for a terrain-adaptive wheel-legged rover. Firstly, the kinematic model of this multi-degree-of-freedom platform is established. Secondly, the deformation capability coefficient, load capacity coefficient, energy efficiency coefficient, and dynamic stability coefficient are derived as performance indices to assess the behavior of the system. By establishing the relationship between joint configuration variation and system stiffness, stiffness parameters could be evaluated through these performance indices. Ultimately, the global optimum stiffness parameters are selected from the refined intersection of the individual performance optimal domains. Thirdly, the optimum parameters are calculated and applicability verified numerically. The designed parameters are verified experimentally on a wheeled-legged rover. The experimental results demonstrate that the proposed algorithm can find the parameter combination that achieves optimal system performance, thereby enhancing the system's terrain adaptability.

N-Dimensional non-commutative GUP quantization and application to the Bianchi I model

We analyse a n-dimensional Generalized Uncertainty Principle (GUP) quantization framework, characterized by a non-commutative nature of the configurational variables. First, we identify a set of states which are maximally localized only along a single direction, at the expense of being less localized in all the other ones. Subsequently, in order to recover information about localization on the whole configuration space, we use the only state of the theory which exhibits maximal localization simultaneously in every direction to construct a satisfactory quasi-position representation, by virtue of a suitable translational operator. The resultant quantum framework is then applied to model the dynamics of the Bianchi I cosmology. The corresponding Wheeler–DeWitt equation is reduced to Schrödinger dynamics for the two anisotropy degrees of freedom, using a WKB representation for the volume-like variable of the Universe, in accordance with the Vilenkin scenario. The main result of our cosmological implementation of the constructed quantum theory demonstrates how the dynamics of a wave packet peaked at some point in the configuration space represented in the quasi-position variables favours as the most probable configuration exactly the initial one for a relatively long time, if compared with the ordinary quantum theory. This preference arises from the different dynamical behavior exhibited by wave packets in the two quantum theories.

Effects of Wire-Wrapping Patterns and Low Temperature on Combustion of Propellant Embedded with Metal Wire

Incorporating silver wires into propellant has emerged as a highly effective strategy for enhancing propellant burning rates, a technique extensively deployed in the construction of numerous fielded sounding rockets and tactical missiles. Our research, employing a multi-faceted approach encompassing thermogravimetric-differential scanning calorimetry measurements (TG-DSC), combustion diagnoses, burning rate tests, and meticulous collection of condensed combustion products, sought to elucidate how variations in silver wire quantity and winding configuration impact the combustion properties of propellants. Our findings underscore the remarkable efficacy of double tightly twisted silver wire in significantly boosting propellant burning rates under ambient conditions. Moreover, at lower temperatures, the reduced gap between the propellant and silver wire further magnifies the influence of silver wire on burning rates. However, it is noteworthy that the relationship between burning speed and combustion efficiency is not deterministic. While a smaller cone angle of the burning surface contributes to heightened burning rates, it concurrently exacerbates the polymerization effect of vapor phase aluminum particles, consequently diminishing propellant combustion efficiency. Conversely, propellants configured with sparsely twinned silver wires exhibit notable enhancements in combustion efficiency, despite a less pronounced impact on the burning rate attributed to the larger cone angle of the burning surface. Remarkably, these trends persist at lower temperatures. Based on the principle of heat transfer balance, a theoretical model for the combustion of propellants with wire inserts is developed. The reliability of this theoretical model is validated through a comparison of calculated values with experimental data. Our research outcomes carry significant implications for guiding the application and advancement of the silver wire method in solid propellants for solid rocket motors, offering valuable insights to inform future research and development endeavors in this domain.

Rationalizing Acidic Oxygen Evolution Reaction over IrO2: Essential Role of Hydronium Cation.

The development of active, stable, and more affordable electrocatalysts for acidic oxygen evolution reaction (OER) is of great importance for the practical application of electrolyzers and the advancement of renewable energy conversion technologies. Currently, IrO2 is the only catalyst with high stability and activity, but a high cost. Further optimization of the catalyst is limited by the lack of understanding of catalytic behaviors at the acid-IrO2 interface. Here, in strong interaction with the experiment, we develop an explicit model based on grand-canonical density function theory (GC-DFT) calculations to describe acidic OER over IrO2. Compared to the explicit models reported previously, hydronium cations (H3O+) are introduced at the electrochemical interface in the current model. As a result, a variation in stable IrO2 surface configuration under the OER operating condition from previously proposed complete *O-coverage to a mixture coverage of *OH and *O is revealed, which is well supported by in situ Raman measurements. In addition, the accuracy of predicted overpotential is increased in comparison with the experimentally measured. More importantly, an alteration of the potential limiting step from previously identified *O → *OOH to *OH → *O is observed, which opens new opportunities to advance the IrO2-based catalysts for acidic OER.