9‐Substituted carbazoles are widely used units in materials science, and their oxidative reactions have been utilized for the synthesis and characterization of polymers. Though the oxidative ...mechanism of carbazoles has been known for a few decades, structural definition has remained difficult, because their polymers are generally insoluble with incomplete characterization and unknown dependence of the electrochemical potentials. The oxidative reactions of 9‐substituted carbazoles should be carefully considered under specific oxidative conditions; otherwise, structure definitions could be wrong, because the IR and NMR spectra used previously cannot quantitatively analyze 3,3′‐coupling and 6,6′‐coupling of carbazoles. In this review, the best understanding of the C3−C3′ and C6−C6′ oxidative couplings of 9‐substituted carbazoles is presented, and the benefit of these oxidative reactions from the viewpoints of electrochemical synthesis, film engineering, and the synthesis and processing of polymers is highlighted.
Couple up! 9‐Substituted carbazoles are widely used units in materials science, and their oxidative reactions have been utilized for the synthesis and characterization of polymers. Herein, controlled C3−3′ and C6−6′ coupling reactions of 9‐alkylcarbazoles are defined and understood from the viewpoints of electrochemical synthesis, film engineering, and the synthesis and processing of polymers.
Given increasing environmental issues due to the large usage of non‐biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are ...in high demand. One feasible strategy is the bio‐inspired synthesis of mineral‐based hybrid materials. Herein we report a facile route for an amorphous CaCO3 (ACC)‐based hydrogel consisting of very small ACC nanoparticles physically cross‐linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self‐healable. Upon drying, the hydrogel forms free‐standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the “mineral plastics”.
Shapeable, stretchable, recyclable, (thermochromic) amorphous calcium carbonate‐based hybrid supramolecular hydrogels were synthesized, which can reversibly form macroscopic rigid transparent films upon drying. This plastic material may potentially replace conventional plastics in a move towards solving environmental issues.
Although biomimetic designs are expected to play a key role in exploring future structural materials, facile fabrication of bulk biomimetic materials under ambient conditions remains a major ...challenge. Here, we describe a mesoscale "assembly-and-mineralization" approach inspired by the natural process in mollusks to fabricate bulk synthetic nacre that highly resembles both the chemical composition and the hierarchical structure of natural nacre. The millimeter-thick synthetic nacre consists of alternating organic layers and aragonite platelet layers (91 weight percent) and exhibits good ultimate strength and fracture toughness. This predesigned matrix-directed mineralization method represents a rational strategy for the preparation of robust composite materials with hierarchically ordered structures, where various constituents are adaptable, including brittle and heat-labile materials.
A Ni‐catalyzed hydroarylation of styrenes and 1,3‐dienes with organoboron compounds has been developed. The reaction offers a highly selective approach to diarylalkanes and allylarenes under ...redox‐neutral conditions. In this hydroarylation reaction, a new strategy that uses the proton of methanol to generate the active catalyst species Ni−H was developed. The Ni‐catalyzed hydroarylation, combined with a Ir‐catalyzed C−H borylation, affords a very efficient and straightforward access to a retinoic acid receptor agonist.
OH yeah: A nickel(0)‐catalyzed hydroarylation of alkenes with organoboron reagents using an alcohol OH group as the H‐atom source is reported. The reaction offers a highly selective approach to diarylalkanes and allylarenes under redox‐neutral conditions.
This study investigated primary mathematics teachers’ technological, pedagogical, and content knowledge (TPACK) and attitudes towards information and communication technology (ICT) integration in ...mainland China during the post-pandemic period. Quantitative data were collected through a web-based self-determined questionnaire. Statistical analysis was performed using independent sample t-tests, and Mann-Whitney U tests to assess gender and teaching experience in years. Spearman’s correlation test also examined the relationship between TPACK and teachers’ attitudes towards ICT integration. The findings revealed that most mathematics teachers had adequate non-technology-related knowledge but lacked technology-related knowledge. However, they were willing to incorporate digital technologies in their teaching after experiencing large-scale online teaching. There was no significant gender or teaching grade differences in TPACK, but teaching experience positively correlated with TPACK. The study emphasizes the importance of assessing teachers’ practical circumstances before introducing TPACK development programs. Finally, the implications for teachers, educators, and policymakers were discussed at the end of this paper.
In this paper we construct the Poincare line bundle for the stack of Higgs bundles on smooth projective curves and show that it induces a fully-faithful Fourier-Mukai transform on the category of ...quasi-coherent sheaves.
This study was dedicated to developing the Scale of Mathematics Teachers’ Technology Integration (SMTTI), a comprehensive instrument designed to assess the competencies of primary mathematics ...teachers in integrating digital technologies. The research encompassed data collection through a web-based questionnaire distributed to mathematics teachers across Chongqing, China. Both exploratory and confirmatory factor analyses were conducted to determine the SMTTI's efficacy as a measurement tool. These analyses established the robust reliability and validity of the SMTTI, affirming its effectiveness as an instrument for assessing the technology integration capabilities of mathematics teachers. The scale exhibited excellent psychometric properties, characterized by strong factor loadings, high internal consistency, and good model fit indices. The SMTTI advances educational technology research by providing a nuanced self-efficacy assessment tool that aligns with the emergent needs of post-pandemic education environments. Its distinctiveness lies in its empirical foundation and tailored approach to evaluating primary mathematics teachers’ self-efficacy for technology integration. The scale fills a critical gap in the existing literature by delivering a context-specific tool designed for the post-digital transition in educational practice, aiding in the formulation of targeted professional development programs and policy making. This addresses a need for updated instruments in the field, complementing the self-reported surveys focusing on practical application and current educational demands. The SMTTI contributes to refining the use of digital technology in educational settings by providing an instrument sensitive to the context-specific needs of teachers, thereby supporting more accurate instruments in this evolving domain.
Various methods have been exploited to replicate nacre features into artificial structural materials with impressive structural and mechanical similarity. However, it is still very challenging to ...produce nacre-mimetics in three-dimensional bulk form, especially for further scale-up. Herein, we demonstrate that large-sized, three-dimensional bulk artificial nacre with comprehensive mimicry of the hierarchical structures and the toughening mechanisms of natural nacre can be facilely fabricated via a bottom-up assembly process based on laminating pre-fabricated two-dimensional nacre-mimetic films. By optimizing the hierarchical architecture from molecular level to macroscopic level, the mechanical performance of the artificial nacre is superior to that of natural nacre and many engineering materials. This bottom-up strategy has no size restriction or fundamental barrier for further scale-up, and can be easily extended to other material systems, opening an avenue for mass production of high-performance bulk nacre-mimetic structural materials in an efficient and cost-effective way for practical applications.Artificial materials that replicate the mechanical properties of nacre represent important structural materials, but are difficult to produce in bulk. Here, the authors exploit the bottom-up assembly of 2D nacre-mimetic films to fabricate 3D bulk artificial nacre with an optimized architecture and excellent mechanical properties.
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