Structural Framework Research Articles

Characterizing the Behavior of Water Interacting with a Nano-Pore Material: A Structural Investigation in Native Environment Using Magnetic Resonance Approaches.

The study of fluid absorption, particularly that of water, into nanoporous materials has garnered increasing attention in the last decades across a broad range of disciplines. However, most investigation approaches to probe such behaviors are limited by characterization conditions and may lead to misinterpretations. In this study, a combined MRI and MAS NMR method was used to study a nanoporous silica glass to acquire information about its structural framework and interactions with confined water in a native humid environment. Specifically, MRI was used for a quantitative analysis of water extent. While MAS NMR techniques provided structural information of silicate materials, including interactive surface area and framework packing. Analysis of water spin-spin relaxation times (T2) suggested differences in water confinement within the characterized framework. Subsequent unsuccessful delivery of paramagnetic molecule into the pores enabled a quantitative assessment of the dimensions that "bottleneck" the pores. Finally, pore sizes were derived from the paramagnetic molecular size, density function theory (DFT) simulation and characterizations on standard samples. Our result matches with Brunauer-Emmett-Teller (BET) analysis that the pore size is less than 1.3 nm. The use of a paramagnetic probe for pore size determination introduces a new approach of characterization in the liquid phase, offering an alternative to the conventional BET analysis that uses gas molecule as probes.

Assembly of Copper Alkynyl Clusters into Dimensionally Diverse Coordinated Polymers Mediated by Pyridine Ligands.

Surface ligands play crucial roles in modifying the properties of metal nanoclusters and stabilizing atomically precise structures, and also serve as vital linkers for constructing cluster-based coordination polymers. In this study, we present the results of the solvothermal synthesis of eight novel copper alkynyl clusters incorporating pyridine ligands using a one-pot method. The resulting compounds underwent characterization through elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD). Our observations revealed that distinct pyridine ligands with varying lengths and coordination sites exert significant influence on the structure and dimensionality of the clusters. The structural diversity of these clusters led to the formation of one-dimensional (1D), two-dimensional (2D), or dimer arrangements linked by seven pyridine bridging ligands. Remarkably, these complexes exhibited unique UV-vis absorption and photoluminescence properties, which were influenced by the specific bridging ligand and structural framework. Furthermore, density functional theory (DFT) calculations demonstrated the capability of the conjugated system in the pyridine ligand to impact the band gap of clusters. This study not only unveils the inherent structural diversity in coordination polymers based on copper alkynyl clusters but also offers valuable insights into harnessing ligand engineering for structural and property modulation.

Spatial structure digital twins: Application in intelligent health monitoring of cable dome structures

Traditional structural health monitoring (SHM) based on contact sensors has drawbacks, such as high cost, susceptibility to interference, and narrow coverage. Digital twins (DTs) present an effective intelligent solution. However, the real-time monitoring of all structural components remains challenging due to high computational cost of high-order models in underlying framework. Additionally, the vast number of spatial structures globally and their long service time indicate the potential necessity of introducing SHM based on DT. In this context, this study proposed a reduced-order model-based DT framework for spatial structures. By compressing the experimental design samples, the multidimensional high-order physical models were reduced to several approximate low-order models for constructing a DT model, thereby achieving real-time calculation covering all components. The proposed framework was applied and validated through an experiment on a scale model of cable dome structure, and real-time interactive visualisation of monitoring data was displayed on a self-developed platform. The results demonstrate that the DT model enabled real-time presentation of calculation results (the calculation speed of <0.5 s/time), the mean relative error of cable tension monitoring was <3.85%, the strut stress monitoring could be controlled within 7.5%, and the mean absolute error of nodal displacement could be maintained at around 1 mm.

Impact of active learning instruction in blended learning on students' anxiety levels and performance

IntroductionContemporary educational research has extensively explored the link between anxiety and student performance, yet there's a gap in understanding this relationship in classrooms with varying levels of active learning. This study aims to establish connections between instructional design, anxiety levels, and student performance, ultimately creating a comprehensive theoretical framework.MethodsThis study was conducted during the pandemic. Data from 186 respondents at Northeast Forestry University were collected through an online survey, and 25 students were randomly selected for interviews to gather feedback. In the practical application of the introductory course “Basics Product Design,” the Rain Class software was used to facilitate an active learning environment. Data from the online survey were organized in SPSS, then imported into the structural model framework in AMOS to calculate fit indices and other values to test hypotheses, applying structural equation modeling. Additionally, the relationship between anxiety levels and student performance was analyzed based on data from five classes using different instructional designs.ResultsThe results indicated that cold calling was significantly positively correlated with anxiety levels (SE = 0.632, P &amp;lt; 0.001), group work was significantly positively correlated with anxiety (SE = 0.166, P &amp;lt; 0.05), clickers were not significantly positively correlated with anxiety (SE = 0.188, P &amp;gt; 0.05), and anxiety levels were not significantly negatively correlated with student performance (SE = −0.306, P &amp;gt; 0.05). Mediation effect tests revealed that anxiety levels fully mediated the relationship between the use of clickers and student performance. Comparing student performance and anxiety levels across the five classes, the relationship between anxiety levels and student performance did not show a simple positive or negative correlation but followed a fluctuating curve, with an interval of anxiety levels that promotes student performance.DiscussionIn a blended learning environment, different designs and frequencies of active learning activities can lead to varying levels of anxiety, which in turn affect student performance. One prominent factor in increasing student anxiety is cold calling. The findings can serve as a basis for teachers to design educational plans, helping to create classroom environments that foster active participation and maintain a positive state among students. Furthermore, in this instructional environment, it is worth further investigating the factors influencing student anxiety and the impact of anxiety on student academic performance.

Diol Struts Stabilize the Structure of a 3D Hydrogen-Bonded Framework with Large Cavities: Inclusion of Solvated Nile Red in the Solid State

Diol Struts Stabilize the Structure of a 3D Hydrogen-Bonded Framework with Large Cavities: Inclusion of Solvated Nile Red in the Solid State

Construction of sub micro-nano-structured silicon based anode for lithium-ion batteries

The significant volume change experienced by silicon (Si) anodes during lithiation/delithiation cycles often triggers mechanical-electrochemical failures, undermining their utility in high-energy-density lithium-ion batteries (LIBs). Herein, we propose a sub micro-nano-structured Si based material to address the persistent challenge of mechanic-electrochemical coupling issue during cycling. The mesoporous Si-based composite submicrospheres (M-Si/SiO2/CS) with a high Si/SiO2 content of 84.6 wt.% is prepared by magnesiothermic reduction of mesoporous SiO2 submicrospheres followed by carbon coating process. M-Si/SiO2/CS anode can maintain a high specific capacity of 740 mAh g−1 at 0.5 A g−1 after 100 cycles with a lower electrode thickness swelling rate of 63%, and exhibits a good long-term cycling stability of 570 mAh g−1 at 1 A g−1 after 250 cycles. This remarkable Li-storage performance can be attributed to the synergistic effects of the hierarchical structure and SiO2 frameworks. The spherical structure mitigates stress/strain caused by the lithiation/delithiation, while the internal mesopores provide buffer space for Si expansion and obviously shorten the diffusion path for electrolyte/ions. Additionally, the amorphous SiO2 matrix not only servers as support for structure stability, but also facilitates the rapid formation of a stable solid electrolyte interphase layer. This unique architecture offers a potential model for designing high-performance Si-based anode for LIBs.

The C-BixSnSb composite toward fast-charging and long-life sodium-ion batteries

Sodium ion batteries (SIBs) fitted with high-rate and high-capacity anodes are attractive for their higher energy density and faster charging capability. However, it is still a challenge to develop high-energy SIBs with high power and long life, due to the sluggish kinetic and limited Na+ insertion in electrode materials. The inherent crystal structure and constituent element are two important factors to resolve the critical issues faced above. Taking the merits of layer-structure and middle-entropy, herein, we proposed and designed a high ion-conductive composite combing with ternary alloy and layered BixSnSb@C nanofibers, which eliminate ion migration barriers while maintaining the structural framework for superior rate property and cycle stability. Used as anode for SIBs, the multiphase BixSnSb@C with adjustable Bi content exhibits excellent Na storage capability as compared to their single phase counterpart. Specially, up to a rate of 132C (50 A g−1), the capacity is still as high as 400 mAh g−1, meanwhile, after 5000 charge and discharge cycles at a current density of 12C, the capacity still maintains 85 % of its initial capacity, which outperform the individual Bi- or SnSb-based materials. The superior electrochemical performances originate from the middle-entropy nature and layer structure of BiSnSb alloy, which can provide more channels for fast Na+ transport, and accommodate large volume changes. Besides, the activity energy and ions transport resistance of Na+ in different composites were evaluated. Furthermore, the full-cell coupled with NaNi1/3Fe1/3Mn1/3O2 as cathode was formed and a capacity retention of ∼80 % is realized in 100 cycles. The results show that the BixSnSb@C is a potential anode for fast-charging Na-ion batteries and could be used to guide the design of multi-component alloy-base anodes.

Productivity and efficiency: Do we need a bridge?

The paper focuses on comparing two popular approaches to estimating firm production technology: the proxy-variable method and the stochastic frontier (SF) analysis approach. We show that although the economic interpretations of productivity and efficiency are not the same, the difference between them is not fundamental and even trivial as far as the estimation techniques are concerned when the same structural framework is assumed. By showing the connection and comparing the difference between these two methods, this paper is aimed at building a bridge to connect these two strands of literature. In addition, we provide the SF audience with a new estimation method, i.e., the modified proxy-variable method, with its advantages in handling the endogeneity issue, along with a new way to estimate technical inefficiency. We examine their finite sample performance using Monte Carlo simulations. In the empirical section, we compare the proposed estimator with the conventional MLE SF estimator using Chinese manufacturing firms in the computer and peripheral sector over the period 1998 to 2007. We find that the estimates from our method are more reasonable in explaining the production behavior of these firms, and firms’ technical inefficiency levels are highly persistent over time.

Enhancing vibration energy dissipation and self-powered sensing in high-rise buildings using origami-inspired triboelectric nanogenerators and buckling-restrained braces

This study introduces a novel Buckling-Restrained Brace (BRB) design, incorporating Origami-inspired structures (OS) with triboelectric nanogenerators (TENGs), creating an intelligent BRB system for both vibration damping during seismic events and self-powered sensing. Rooted in the Miura-tube pattern, we conducted an extensive array of mechanical tests, encompassing varying contact shapes, external resistances, and excitation frequencies. Addressing the challenge of motion synchronicity in the OS base, we introduce an enhanced Miura-tube OS-TENG, featuring reinforced stiffness in the origami structure's creases and panels. Our experiments revealed that the signal strength of these refined devices proportionally escalates with the number of integrated tribo-pairs. Further vibrational analysis of a two-story frame equipped with this enhanced Miura-tube OS-TENG underscored its potential as a sophisticated intelligent BRB. Experiments demonstrated a significant 31.21 % reduction in structural acceleration and a strong correlation between the device's voltage output and the building's dynamic response, with a 90.40 % regression fit. Within the examined range of excitation frequencies 3–15 Hz, the average accuracy of predicting structural acceleration using intelligent BRBs is 92.90 %. This work not only meets the essential demand for vibration mitigation through the innovative use of intelligent OS-TENG BRB systems but also significantly advances the integration of TENG-based self-powered sensors in structural health monitoring frameworks.

A Comprehensive Review of the Docking Studies of Chalcone for the Development of Selective MAO-B Inhibitors.

Monoamine oxidase B is a crucial therapeutic target for neurodegenerative disorders like Alzheimer's and Parkinson's since they assist in disintegrating neurotransmitters such as dopamine in the brain. Pursuing efficacious monoamine oxidase B inhibitors is a hot topic, as contemporary therapeutic interventions have many shortcomings. Currently available FDA-approved monoamine oxidase inhibitors like safinamide, selegiline and rasagiline also have a variety of side effects like depression and insomnia. In the quest for a potent monoamine oxidase B inhibitor, sizeable, diverse chemical entities have been uncovered, including chalcones. Chalcone is a renowned structural framework that has been intensively explored for its monoamine oxidase B inhibitory activity.The structural resemblance of chalcone (1,3-diphenyl-2-propen-1-one) based compounds and 1,4-diphenyl- 2-butene, a recognized MAO-B inhibitor, accounts for their MAO-B inhibitory activity. Therefore, multiple revisions to the chalcone scaffold have been attempted by the researchers to scrutinize the implications of substitutions onthe molecule's potency. In this work, we outline the docking investigation results of various chalcone analogues with monoamine oxidase B available in the literature until now to understand the interaction modes and influence of substituents. Here we focused on the interactions between reported chalcone derivatives and the active site of monoamine oxidase B and the influence of substitutions on those interactions. Detailed images illustrating the interactions and impact of the substituents or structural modifications on these interactions were used to support the docking results.

Cationic manganese(II)-based metal-organic framework constructed from viologen derivative with multifunctional properties

Utilizing the rigid and linear viologen carboxylic ligand as an organic linker, we have successfully synthesized and structurally characterized a multifunctional Mn-based cationic metal-organic framework (1). Compound 1 features a three-dimensional framework structure with a positively charged skeleton, wherein triangular pores accommodate [MnCl4]2− anions to preserve charge neutrality. Notably, compound 1 demonstrates a chemical chromism phenomenon, transitioning from yellow-brown to deep green upon exposure to ammonia. This color change is attributed to the nucleophilic attack of electron-rich ammonia molecules on the electron-deficient viologen moiety of viologen carboxylic ligand, leading to the formation of viologen radicals and charge transfer complexes. Moreover, compound 1 exhibits rapid and selective detection of antibiotics like metronidazole (MDZ) and dimetridazole (DTZ) via a competitive absorption-induced luminescence quenching process, featuring high quenching coefficients and low detection limits. Additionally, magnetic property investigations reveal predominant antiferromagnetic coupling between Mn(II) ions within compound 1.

Modeling of fluid flow along a small heated irregularity on the plate surface in the framework of double-deck boundary layer structure

Modeling of fluid flow along a small heated irregularity on the plate surface in the framework of double-deck boundary layer structure

Comparative Analysis of Framed-Tube &amp; Braced-Tube System in Tall Buildings Using ETABS

Abstract: Since the rigid frame became popular in the first half of the 20th century, tall buildings with structural systems have evolved. The development of underlying frameworks for tall structures lays on reasonable realism, economy of material utilization, effortlessness and polish, and worry for constructability. We are now able to build buildings that are ever higher thanks to cutting-edge building materials, sophisticated computational software, and sturdy structural systems. The rationale behind the creation of structural systems for tall buildings is to achieve architectural expression, ensure safety and serviceability, and make rational and effective use of materials. The use of composite structures, which combine the advantages of various materials, has been the trend in structural systems for tall buildings. In both static and dynamic conditions, these high-rise structures ought to be able to withstand a variety of lateral loads, such as wind load and earthquake load. This study examines the responses of the Framed Tube, Braced Tube, structural systems to various parameters such as Story displacement, Story drift, Story shear, and time period. The analysis focuses on 60-story structures situated in Seismic Zone III with medium soil conditions. The static analysis of the structures is conducted using the linear static method, which involves wind load calculations using the force coefficient method. On the other hand, the dynamic analysis is performed using the response spectrum method, with wind load calculations carried out using the gust factor calculation method.

The Impact of Structural Racism on Continuity of Care at Pediatric Academic Primary Care Clinics

ObjectiveUsing a structural racism framework, we assessed racial inequities in continuity of care, using the Usual Provider Continuity Index (UPC – the proportion of visits with the provider the patient saw most frequently out of all visits), in a set of large pediatric academic clinics. MethodsWe conducted a retrospective cohort study. Patients 12–24 months seen at three pediatric academic primary care clinics for any visit during October 1–31, 2021 were included. We then reviewed continuity for these patients in the preceding 12 months. Outcomes included each patient’s UPC for all visits, and a modified UPC for well child checks only (UPC Well). Covariates included race, ethnicity, insurance, clinic site, age, sex, care management, or seeing a social worker. We evaluated for differences in outcomes using bivariate analyses and multivariable regression models. ResultsOur cohort included 356 patients (74% Black, 5% Hispanic, 85% Medicaid, 52% female, median age 15.8 months). The median UPC was 0.33 and median UPC Well was 0.40. Black patients had significantly lower median values for UPC (0.33 Black vs 0.40 non-Black, P < .01) and UPC Well (0.33 Black vs 0.50 non-Black, P < .01). There were similar inequities in continuity rates by insurance and clinic site. In multivariable models, clinic site was the only variable significantly associated with continuity. ConclusionsClinic sites serving higher percentages of Black patients had lower rates of continuity. The main driver of racial inequities in continuity rates was at the institutional level.

The technology or the child? Moving beyond technological fixes in deaf education in India and elsewhere

ABSTRACT As cochlear implants become the gold standard in intervening on deafness around the world, teachers of deaf children are increasingly expected to have technological expertise and to ensure that cochlear implants, and other hearing technology, are being used and that they are working. Students are only considered “ready to learn” if they are using their technology. Drawing from ethnographic research and semi-structured interviews with educators, families, surgeons, speech and language therapists, and audiologists in Indian cities, this article mobilises two conceptual frameworks from medical anthropology and public health – the “biotechnical embrace” and the “structural competency framework” to argue that teachers of deaf children, both in India and internationally, need to think and work beyond technology. Ultimately, focusing on a child does not mean focusing (only) on technology but rather on seeing a child as enmeshed in social, political, educational, and economic structures and relations. Expanding educators’ focus to consider micro and macro scales is especially urgent now, as countries around the world implement programmes in which technology is the goal.

A Structural Framework for Effective Time Management in Dynamic Work Environments

This paper presents a structural framework to enhance time management profi- ciency within dynamic work environments. The framework integrates prioritization techniques, task scheduling methods, delegation strategies, and technology utilization to optimize time allocation and productivity. The evaluation demonstrates significant improvements in time management efficiency and client satisfaction across various professional contexts. For instance, by employing the eisenhower Matrix and Pareto Principle, project managers achieved a 20% im- provement in project completion times. The framework’s adaptability is further highlighted by a 25% reduction in project turnaround time in a marketing agency and a 30% increase in project visibility in a startup. These findings underscore the framework’s practical implementation as a holistic approach to managing time effectively and achieving long-term success. Continuous refinement, real- time feedback integration, and exploring the impact of emerging technologies are recommended for further enhancing the framework’s effectiveness. This research contributes valuable insights for organizations aiming to navigate the complexities of modern work environments.

Variation in structural motifs within SARS-related coronavirus spike proteins.

SARS-CoV-2 is the third known coronavirus (CoV) that has crossed the animal-human barrier in the last two decades. However, little structural information exists related to the close genetic species within the SARS-related coronaviruses. Here, we present three novel SARS-related CoV spike protein structures solved by single particle cryo-electron microscopy analysis derived from bat (bat SL-CoV WIV1) and civet (cCoV-SZ3, cCoV-007) hosts. We report complex glycan trees that decorate the glycoproteins and density for water molecules which facilitated modeling of the water molecule coordination networks within structurally important regions. We note structural conservation of the fatty acid binding pocket and presence of a linoleic acid molecule which are associated with stabilization of the receptor binding domains in the "down" conformation. Additionally, the N-terminal biliverdin binding pocket is occupied by a density in all the structures. Finally, we analyzed structural differences in a loop of the receptor binding motif between coronaviruses known to infect humans and the animal coronaviruses described in this study, which regulate binding to the human angiotensin converting enzyme 2 receptor. This study offers a structural framework to evaluate the close relatives of SARS-CoV-2, the ability to inform pandemic prevention, and aid in the development of pan-neutralizing treatments.

Carbon coated and oxygen vacancies incorporated Wadsley-Roth phase molybdenum niobium oxide for high-performance lithium-ion storage

Nb-based oxides with Wadsley-Roth shear structure have been aroused extensive research interest as promising anode for Li-ion batteries, due to the multi-electron redox, safe working voltage and open structural framework. However, the low intrinsic electronic conductivity limits their further practical applications. Herein, the lithium storage performances of MoNb6O18 with Wadsley-Roth shear structure are optimized by carbon coating and oxygen vacancies (VO-MNO@C), which synthesized with freeze-drying and subsequently heat treatment. As expected, the VO-MNO@C electrode demonstrates a high initial reversible capacity of 259.6 mAh/g at 0.2C and the capacity retention rate of 85.7 % after 200 cycles at 1C. Moreover, the reversible of Mo6+/Mo5+ and Mo5+/Mo4+ redox reaction can be effectively improved. In situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) characterization indicate that VO-MNO@C undergoes a solid-solution structural evolution disclosing the stepwise reaction of Mo5+/Mo6+, Mo4+/Mo5+, Nb4+/Nb5+ and Nb3+/Nb4+ redox couples with a small volume variation of 5.7 %. Also, the full cell based on commercial LiMn2O4 cathode and VO-MNO@C anode displays an operating voltage about 2.4 V with the high energy density of 681.4 Wh/kg (calculated with the mass of anode). This work will offer more insights for the development of Wadsley-Roth shear structure anode materials with excellent Li-ion storage properties.

Impact of social determinants of health on progression from potentially life-threatening complications to near miss events and death during pregnancy and post partum in a middle-income setting: an observational study

ObjectiveTo assess the potential associations between social determinants of health (SDH) and severe maternal outcomes (SMO), to better understand the social structural framework and the contributory, non-clinical mechanisms associated with...

Revealing the hidden structure of disordered materials by parameterizing their local structural manifold

Durable interest in developing a framework for the detailed structure of glassy materials has produced numerous structural descriptors that trade off between general applicability and interpretability. However, none approach the combination of simplicity and wide-ranging predictive power of the lattice-grain-defect framework for crystalline materials. Working from the hypothesis that the local atomic environments of a glassy material are constrained by enthalpy minimization to a low-dimensional manifold in atomic coordinate space, we develop a generalized distance function, the Gaussian Integral Inner Product (GIIP) distance, in connection with agglomerative clustering and diffusion maps, to parameterize that manifold. Applying this approach to a two-dimensional model crystal and a three-dimensional binary model metallic glass results in parameters interpretable as coordination number, composition, volumetric strain, and local symmetry. In particular, we show that a more slowly quenched glass has a higher degree of local tetrahedral symmetry at the expense of cyclic symmetry. While these descriptors require post-hoc interpretation, they minimize bias rooted in crystalline materials science and illuminate a range of structural trends that might otherwise be missed.