Development Of Materials Research Articles

Orchestrated Octuple C−H Activation: A Bottom‐Up Topology Engineering Approach toward Stimuli‐Responsive Double‐Heptagon‐Embedded Wavy Polycyclic Heteroaromatics

AbstractCuriosity‐driven innovations on the design and synthesis of nonplanar polycyclic aromatic/heteroaromatic compounds with new molecular topologies unfold exciting opportunities for harnessing their intriguing supramolecular properties and thereby the development of novel functional organic materials. This work presents such an innovative synthetic concept of a bottom‐up molecular topology engineering through a unique orchestrated octuple C−H activation reaction, toward the rapid synthesis of a novel class of double heptagon‐incorporated nitrogen‐doped laterally‐fused polycyclic compounds with rarely reported wavy structural configuration. The profound impact of the molecular wavy structures of these compounds on their properties is manifested by weak and tunable solid‐state intermolecular interactions controlling the electronic properties of the materials, leading to reversibly switchable fluorochromism in the solid state and thin films with mechanical force and solvent vapors as external stimuli, thereby indicating their potential applicability in rewritable fluorescent optical recording media, security papers, mechanosensors, volatile organic compound (VOC) sensors etc.

Orchestrated Octuple C-H Activation: A Bottom-Up Topology Engineering Approach toward Stimuli-Responsive Double-Heptagon-Embedded Wavy Polycyclic Heteroaromatics.

Curiosity-driven innovations on the design and synthesis of nonplanar polycyclic aromatic/heteroaromatic compounds with new molecular topologies unfold exciting opportunities for harnessing their intriguing supramolecular properties and thereby the development of novel functional organic materials. This work presents such an innovative synthetic concept of a bottom-up molecular topology engineering through a unique orchestrated octuple C-H activation reaction, toward the rapid synthesis of a novel class of double heptagon-incorporated nitrogen-doped laterally-fused polycyclic compounds with rarely reported wavy structural configuration. The profound impact of the molecular wavy structures of these compounds on their properties is manifested by weak and tunable solid-state intermolecular interactions controlling the electronic properties of the materials, leading to reversibly switchable fluorochromism in the solid state and thin films with mechanical force and solvent vapors as external stimuli, thereby indicating their potential applicability in rewritable fluorescent optical recording media, security papers, mechanosensors, volatile organic compound (VOC) sensors etc.

Unlocking the Potential of Polythioesters.

As the demand for sustainable polymers increases, most research efforts have focused on polyesters, which can be bioderived and biodegradable. Yet analogous polythioesters, where one of the oxygen atoms has been replaced by a sulfur atom, remain a relatively untapped source of potential. The incorporation of sulfur allows the polymer to exhibit a wide range of favorable properties, such as thermal resistance, degradability, and high refractive index. Polythioester synthesis represents a frontier in research, holding the promise of paving the way for eco-friendly alternatives to conventional polyesters. Moreover, polythioester research can also open avenues to the development of sustainable and recyclable materials. In the last 25 years, many methods to synthesize polythioesters have been developed. However, to date no industrial synthesis of polythioesters has been developed due to challenges of costs, yields, and the toxicity of the by-products. This review will summarize the recent advances in polythioester synthesis, covering step-growth polymerization, ring-opening polymerization (ROP), and biosynthesis. Crucially, the benefits and challenges of the processes will be highlighted, paying particular attention to their sustainability, with the aim of encouraging further exploration and research into the fast-growing field of polythioesters.

The Ferroelectric Effects of Rhombohedral and Tetragonal BiFeO3 in Photoelectrochemical Water Splitting.

The phase of BiFeO3 (BFO) as well as its domain configuration can be tuned by strain engineering. Phase change may greatly influence the properties of the polarization field and hence charge separation. However, the photoelectrochemical properties of different BFO phases have rarely been addressed. Here, the photoelectrochemical study of tetragonal (T-) and rhombohedral (R-) phase BFO films was conducted under visible light illumination. The photocurrent density of R-BFO is 5 times that of T-BFO. A ferroelectric domain study shows that T-BFO features single domain structure in contrast to the polydomain structure of R-BFO. Higher charge separation efficiency is achieved in R-BFO, dominated by the domain walls as conducting pathways for efficient charge separation and transfer. This work provides a fundamental understanding of the photoelectrochemical properties of T- and R-BFO, offering valuable insights for the development of BFO-based materials for solar energy conversion.

Heterointerfaces: Unlocking Superior Capacity and Rapid Mass Transfer Dynamics in Energy Storage Electrodes.

Heterogeneous electrode materials possess abundant heterointerfaces with a localized "space charge effect", which enhances capacity output and accelerates mass/charge transfer dynamics in energy storage devices (ESDs). These promising features open new possibilities for demanding applications such as electric vehicles, grid energy storage, and portable electronics. However, the fundamental principles and working mechanisms that govern heterointerfaces are not yet fully understood, impeding the rational design of electrode materials. In this study, the heterointerface evolution during charging and discharging process as well as the intricate interaction between heterointerfaces and charge/mass transport phenomena, is systematically discussed. Guidelines along with feasible strategies for engineering structural heterointerfaces to address specific challenges encountered in various application scenarios, are also provided. This review offers innovative solutions for the development of heterogeneous electrode materials, enabling more efficient energy storage beyond conventional electrochemistry. Furthermore, it provides fresh insights into the advancement of clean energy conversion and storage technologies. This review contributes to the knowledge and understanding of heterointerfaces, paving the way for the design and optimization of next-generation energy storage materials for a sustainable future.

Finding the joy: effective mentoring in Teacher Education

ABSTRACT Effective support of student teachers is critical to the teaching profession. This research involved student teachers and those who support student teachers on a new two-year Postgraduate teaching course. Using a range of data collection, including creative methods such as the use of artefacts, participants’ interpretations of effective mentoring were explored. It is reported that it is important that mentors volunteer for, and proactively engage in their mentoring role. Also, that sufficient time is allocated to undertake mentoring responsibilities, which include frequent mentor meetings and professional learning. Key aspects identified for effective mentoring include the importance of a trusting relationship between the student teacher and mentor; nurturing student teacher self-reflection and ensuring that student teachers observe a range of teaching styles. The implications of the findings include the improvement and development of support materials for the programme’s mentors along with sharing effective mentoring practice case studies, that showcase effective approaches in different school contexts.

Inducing and Switching the Handedness of Polyacetylenes with Topologically Chiral [2]Catenane Pendants.

To explore the chirality induction and switching of topological chirality, poly[2]catenanes composed of helical poly(phenylacetylenes) (PPAs) main chain and topologically chiral [2]catenane pendants are described for the first time. These poly[2]catenanes with optically active [2]catenanes on side chains were synthesized by polymerization of enantiomerically pure topologically chiral [2]catenanes with ethynyl polymerization site and/or point chiral moiety. The chirality information of [2]catenane pendants was successfully transferred to the main chain of polyene backbones, leading to preferred-handed helical conformations, while the introduction of point chiral units has negligible effect on the overall helices. More interestingly, attributed to unique dynamic feature of the [2]catenane pendants, these polymers revealed dynamic response behaviors to solvents, temperature, and sodium ions, resulting in the fully reversible switching on/off of the chirality induction. This work provides not only new design strategy for novel chiroptical switches with topologically chiral molecules but also novel platforms for the development of smart chiral materials.

Coreactant-Free Zirconium Metal-Organic Framework with Dual Emission for Ratiometric Electrochemiluminescence Detection of HIV DNA.

Owing to the limitations of dual-signal luminescent materials and coreactants, constructing a ratiometric electrochemiluminescence (ECL) biosensor based on a single luminophore is a huge challenge. This work developed an excellent zirconium metal-organic framework (MOF) Zr-TBAPY as a single ECL luminophore, which simultaneously exhibited cathodic and anodic ECL without any additional coreactants. First, Zr-TBAPY was successfully prepared by a solvothermal method with 1,3,6,8-tetra(4-carboxyphenyl)pyrene (TBAPY) as the organic ligand and Zr4+ cluster as the metal node. The exploration of ECL mechanisms confirmed that the cathodic ECL of Zr-TBAPY originated from the pathway of reactive oxygen species (ROS) as the cathodic coreactant, which is generated by dissolved oxygen (O2), while the anodic ECL stemmed from the pathway of generated Zr-TBAPY radical itself as the anodic coreactant. Besides, N,N-diethylethylenediamine (DEDA) was developed as a regulator to ECL signals, which quenched the cathodic ECL and enhanced the anodic ECL, and the specific mechanisms of its dual action were also investigated. DEDA can act as the anodic coreactant while consuming the cathodic coreactant ROS. Therefore, the coreactant-free ratiometric ECL biosensor was skillfully constructed by combining the regulatory role of DEDA with the signal amplification reaction of catalytic hairpin assembly (CHA). The ECL biosensor realized the ultrasensitive ratio detection of HIV DNA. The linear range was 1 fM to 100 pM, and the limit of detection (LOD) was as low as 550 aM. The outstanding characteristic of Zr-TBAPY provided new thoughts for the development of ECL materials and developed a new way of fabricating the coreactant-free and single-luminophore ratiometric ECL platform.

Tailoring of Gelatin-Chitosan Nanofibers Functionalized with Eucalyptus Essential Oil via Electroblowing for Potential Food Packaging and Wound Dressing Applications

AbstractIn recent years, new approaches to fabricating nanofiber networks for potential applications in wound dressing and food packaging have been in the spotlight. This study aimed to produce functional webs based on gelatin, chitosan, and eucalyptus essential oil using the electro-blowing method instead of traditional spinning methods such as electrospinning. The resultant nanofiber webs exhibit promising morphological characteristics, including reduced fiber diameters, enhanced air permeability, and improved thermal stability. The integration of chitosan and eucalyptus essential oil overcomes limitations associated with gelatin, offering enhanced mechanical properties, antibacterial efficacy, and potential attributes for wound healing and food packaging. The combination of gelatin and chitosan contributes to biodegradability and biocompatibility, crucial for developing materials compatible with the natural environment. The addition of eucalyptus essential oil provides an additional layer of antimicrobial protection, aligning with sustainability goals in wound care and active food packaging. A comprehensive analysis encompassing SEM morphologies, fiber diameters, air permeability, FTIR spectra, TGA thermograms, and contact angle measurements establishes a thorough understanding of the fabricated nanofiber webs’ characteristics. Despite the favorable properties exhibited by the developed nanofiber webs for wound healing and food packaging applications, the incorporation of eucalyptus essential oil resulted in a reduction in tensile strength and elongation ratios. This observation highlights the necessity for further optimization and fine-tuning of the formulation to strike a balance between antimicrobial benefits and mechanical properties. Distinguished by its unique combination of gelatin, chitosan, and eucalyptus essential oil, this research contributes to the advancement of nanofiber technology, expanding knowledge in the field and paving the way for the development of advanced materials with enhanced therapeutic properties for wound healing and food packaging. Graphical Abstract

Cobalt Ion-Modified Titanium Oxide Nanorods: A Promising Approach for High-Performance Electrochromic Application

The development of novel cathodic materials with tailored nanostructures is crucial for the advancement of electrochromic devices. In this study, we synthesized cobalt-doped titanium dioxide (Ti-Co) thin films using a facile hydrothermal method to investigate the effects of cobalt doping on their structural, morphological, and electrochromic properties. Comprehensive characterization techniques, including X-ray diffraction and Raman analysis, confirmed the highly crystalline nature of the Ti-Co thin films, with specific Raman bands indicating distinct modifications due to cobalt incorporation. The TiO2 nanorods, optimally doped with cobalt (TC-3), demonstrated enhanced charge transport and mobility, significantly improving the electrochromic performance. Among the various compositions studied, the TC-3 sample exhibited superior lithium-ion accommodation, achieving an optical modulation of 73.6% and a high coloration efficiency of 81.50 cm2/C. It also demonstrated excellent electrochromic stability, maintaining performance for up to 5000 s of coloring/bleaching cycles. These results confirm the beneficial impact of cobalt doping on the structural and functional properties of the host material. Furthermore, the practical effectiveness of the TC-3 thin film was validated through the fabrication of an electrochromic device, which showed efficient coloration and bleaching capabilities. This comprehensive research enhances the understanding and functionality of Ti-Co nanorod architectures, highlighting their promising potential for advanced electrochromic applications.

Rapid quantitative analysis of multiple rare earth elements in NdFeB alloys based on laser-induced breakdown spectroscopy (LIBS) and random forest (RF)

NdFeB material has excellent comprehensive magnetic properties, which plays a crucial role in the field of rare earth magnetic materials, and is one of the important basic materials to support modern high-tech industries. In the production of NdFeB alloys, the control of rare earth elements (REEs) is directly related to the quality and resource utilization efficiency of NdFeB materials. Therefore, the prediction of REEs content in NdFeB alloys is of great research significance and application value for the quality control of products, the enhancement of production efficiency and reduction of energy consumption by the rare earth material industry. In this study, a combination of laser-induced breakdown spectroscopy (LIBS) and random forest (RF) was used to investigate the quantitative analysis of four REEs (Nd, Pr, Tb and Dy) in NdFeB alloys. Firstly, the original LIBS spectra were screened by principal component analysis-mahalanobis distance (PCA-MD). Then, the effects of different data processing methods on the screened LIBS spectra were explored, and next, the feature variables were extracted from the preprocessed spectral data by the variable importance measurement (VIM). In order to further verify the prediction performance of the model, the prediction results of the RF models based on the different methods were compared. Finally, a PCA-VIM-RF calibration model was established on the basis of the optimized spectra, selected feature variables and parameters. Leave-one-out cross validation (LOOCV) was used to optimize the parameters of PCA-MD method, spectral preprocessing method and variable importance thresholds during the construction of the calibration model. The results show that the PCA-VIM-RF model has better prediction performance than the RF calibration model based on the raw spectra. For the PCA-VIM-RF calibration method of Nd, Pr, Tb and Dy elements, the values of R2CV are 0.9991, 0.9998, 0.9986, and 0.9984, respectively, the values of RMSECV are 0.06296%, 0.02788%, 0.04647% and 0.05252%, respectively. The values of R2P are 0.9508, 0.9975, 0.9691 and 0.9457, respectively, and the values of RMSEP are 0.6082%, 0.09205%, 0.5776% and 0.2631%, respectively.The above results indicate that LIBS combined with PCA-VIM-RF algorithm is a promising method for rapid quantitative analysis of REEs in NdFeB alloys without complicated sample preparation, which can provide some new ideas or strategies for the future research, development and quality control of rare earth materials.

Molecular Dynamics Simulation on Polymer Tribology: A Review

A profound comprehension of friction and wear mechanisms is essential for the design and development of high-performance polymeric materials for tribological application. However, it is difficult to deeply investigate the polymer friction process in situ at the micro/mesoscopic scale by traditional research methods. In recent years, molecular dynamics (MD) simulation, as an emerging research method, has attracted more and more attention in the field of polymer tribology due to its ability to show the physicochemical evolution between the contact interfaces at the atomic scale. Herein, we review the applications of MD in recent studies of polymer tribology and their research focuses (e.g., tribological properties, distribution and conformation of polymer chains, interfacial interaction, frictional heat, and tribochemical reactions) across three perspectives: all-atom MD, reactive MD, and coarse-grained MD. Additionally, we summarize the current challenges encountered by MD simulation in polymer tribology research and present recommendations accordingly, aiming to provide several insights for researchers in related fields.

Organic cage-based frameworks: from synthesis to applications

The investigation of organic cage-based frameworks (OCFs) has attracted increasing attention over the past decade due to their versatile synthetic methods and broad property range resulting from the unique combination of porous organic cages (POCs) with diverse framework materials, including porous organic polymers (POPs), metal-organic frameworks (MOFs), and supramolecular organic frameworks (SOFs). Nevertheless, a comprehensive summary of the research advancements in OCFs remains elusive in the literature. This review addresses this gap by providing a detailed overview of the development of OCF-based materials from both synthetic and applicative perspectives. The discussion begins with systematically exploring design principles and common strategies for elaborating OCFs, achieved by rational selection of bond-forming routes suitable for various POC monomers, including covalent bonds, coordination bonds, and supramolecular interactions. Subsequently, the review highlights the functional attributes derived from the distinctive structural features of OCFs, showcasing their task-specific applications in adsorption/separation, catalysis, membrane technology, and other fields. Lastly, the article summarizes the opportunities and challenges anticipated as the exploration of the OCF family continues to advance in material science.

Amelioration of protective organic layer using acenaphthene-based inhibitor responsible for excellent anti-corrosion performance: Experimental and computational perspectives

Despite the engineering promise offered by the co-existence of organic substances in protecting vulnerable metallic materials from corrosive environments, the interaction and formation mechanisms that induce the development of new materials with improved structural properties remain less understood. This study investigated the corrosion inhibitory properties of two acenaphthene derivatives, acenaphthylene-1,2‑dione (ACP) and 1,2-dihydroacenaphthylen-1-ol (DCP), as inhibitors for N80 steel in a 15 % HCl solution. The anticorrosive effectiveness of ACP and DCP compounds was evaluated through multiple research methods, including weight loss analysis, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and surface characterization using scanning electron microscopy (SEM). The experimental findings demonstrate that ACP exhibits superior inhibition performance compared to DCP, with an inhibition efficiency of 93.54 % for ACP and 73.12 % for DCP at an optimum concentration of 5 × 10–3 M. EIS data show that the charge transfer resistance increases with higher concentrations of both compounds. PDP results indicate that ACP and DCP act as mixed-type inhibitors without altering the corrosion mechanism. The kinetic parameters of corrosion adsorption follow the Langmuir isotherm, highlighting a competition between physical and chemical interactions. To investigate how the geometric structures resulting from functional groups influence their interaction with the metal surface, theoretical calculations employing density functional theory (DFT), molecular dynamics (MD), and density-functional tight-binding (DFTB) were conducted. These calculations were aimed at gaining insights into the adsorption behavior of ACP and DCP on the metal surface and their interfacial mechanism. The calculations demonstrate that the molecule possessing twin donor atoms along with p-type orbitals of aromatic rings significantly influenced the formation of a protective film with a uniform distribution. This configuration exhibited superior corrosion performance compared to a molecule containing only one hydroxyl group (—OH). Theoretical calculations further suggest that ACP exhibits stronger adsorption ability, with the two oxygen atoms identified as the most reactive sites, indicating their tendency to donate electrons to the iron surface. The robust resonance-stabilized structure of ACP enhances the stability of the molecules, facilitating its interaction and adsorption onto the metal surface compared to the DCP inhibitor. Overall, the superior inhibition performance of ACP is attributed to the close bonding of twin donor fragments within the ACP molecule, forming a more compact adsorbed inhibitor film on the steel surface.

In silico assessment of biocompatibility and toxicity: molecular docking and dynamics simulation of PMMA-based dental materials for interim prosthetic restorations

Aim: This study aimed to comprehensively assess the biocompatibility and toxicity profiles of poly(methyl methacrylate) (PMMA) and its monomeric unit, methyl methacrylate (MMA), crucial components in dental materials for interim prosthetic restorations. Methodology: Molecular docking was employed to predict the binding affinities, energetics, and steric features of MMA and PMMA with selected receptors involved in bone metabolism and tissue development, including RANKL, Fibronectin, BMP9, NOTCH2, and other related receptors. The HADDOCK standalone version was utilized for docking calculations, employing a Lamarckian genetic algorithm to explore the conformational space of ligand-receptor interactions. Furthermore, molecular dynamics (MD) simulations over 100 nanoseconds were conducted using the GROMACS package to evaluate dynamic actions and structural stability. The LigandScout was utilized for pharmacophore modeling, which employs a shape-based screening approach to identify potential ligand binding sites on protein targets. Results: The molecular docking studies elucidated promising interactions between PMMA and MMA with key biomolecular targets relevant to dental applications. MD simulation results provided strong evidence supporting the structural stability of PMMA complexes over time. Pharmacophore modeling highlighted the significance of carbonyl and hydroxyl groups as pharmacophoric features, indicating compounds with favorable biocompatibility profiles. Conclusion: This study underscores the potential of PMMA in dental applications, emphasizing its structural stability, molecular interactions, and safety considerations. These findings lay a foundation for future advancements in dental biomaterials, guiding the design and optimization of materials for enhanced biocompatibility. Future directions include experimental validation of computational findings and the development of PMMA-based dental materials with improved biocompatibility and clinical performance.Graphical

Tunable colors from responsive 2D materials

AbstractOne of the long‐sought‐after goals in responsive material development is to generate and tune colors for advanced and emerging applications such as dynamic displays, light‐emitting diodes, lasers, smart windows, chromic fabrics, high‐security encryption, and visual sensors. Benefiting from the atomically thin nature as well as strong optical interaction, two‐dimensional (2D) materials can serve as color‐generating centers for both chemical pigment colors and physical interference colors in solution, gels, films, and matrix interface systems, to offer new promises for color science and applications. Concerning color tunability, 2D material systems have been demonstrated as one of the ideal responsive materials to achieve the desired goals, including the change of composition, layer thickness, strain, magic angle, and thermally/photically/chemically responsive, magnetically‐responsive, electrically‐responsive, mechanically‐responsive. This makes it an attractive prospect for device applications such as optoelectronics, displays, and nanomedicine. However, to the best of our knowledge, no comprehensive review has been reported specifically on color‐centered aspects of 2D materials. In this review, we highlight experimental approaches and related applications for tuning pigment colors, reflective structural colors, and transmissive interference colors, and we refine the challenges and propose opportunities in future studies for the further development of color science in the 2D material system. Eventually, it is anticipated that this review will serve as a resource and source of inspiration for scientists, as well as open up new avenues for the advancement of color science and related fields in responsive 2D material systems.

Efficient Energy Storage via Methane Production Using Protonic Ceramic Electrochemical Cells

Protonic ceramic electrochemical cells (PCECs) are promising energy storage technologies due to their high performance and ability to convert CO2 into value-added chemicals. However, there are many fundamental aspects of this technology that require investigation to better understand its interactions and opportunities. Thus, this paper focuses on the development of a steady-state PCEC model, encompassing intricate details of reactive porous-media transport, elementary catalytic chemistry, and electrochemistry within unit cells. The model is calibrated and validated using experimental data. The model presents the rate of methane production at different temperatures and revealed that efficient PCEC for co-electrolysis of CO2 and H2O is operated in the temperature range of 420–470 °C and the optimum being 450 °C at the rate of 0.0391 moldm−3 min−1. It provides insights into the effects of overpotentials on cell performance. At a current density of 3000 A/m2 the ohmic, concentration, and activation overpotentials amount to 0.65, 0.004, and 0.19 V, respectively. The results obtained from the model highlight the potential of PCECs as efficient CO2 sinks for decarbonization purposes and as a means of methane production. Furthermore, the model's findings offer valuable guidance for the design, selection of stacks, and choice of building materials in PCEC systems. The potential applications of PCECs as real-life fuel utilization technologies are justified with improved material development to reduce cell overpotentials, opening doors for scale-up and eventual commercialization. These findings contribute to the development of sustainable energy systems and advance the pursuit of decarbonization goals.

Innovative Approaches for Manufacturing Epoxy-Modified Wood and Cellulose Fiber Composites: A Comparison between Injection Molding and 3D Printing.

The current study focused on improving the properties of polylactic acid (PLA) for wider application in load-bearing scenarios. Various methods were explored to optimize the interaction between PLA and natural fibers, particularly wood fibers (WFs). Alkalized and epoxy-impregnated WFs were evaluated against untreated WFs and cellulose fibers in both injection molding (IM) and fused deposition modeling (FDM). FTIR analysis revealed the removal of hemicellulose and lignin in alkalized WFs and uniform epoxy curing. Addition of fibers reduced PLA's thermal stability while acting as nucleating agents. Additionally, fibers augmented the storage modulus of biocomposites, with alkalized fibers exhibiting the highest tensile modulus in IM. FDM samples with a 0° raster angle showed superior impact resistance compared to IM counterparts. Moreover, raster angle significantly influenced FDM biocomposite properties, enhancing the tensile strength and modulus of untreated WF and cellulose fibers at 0°. Although FDM did not produce alkalized WF samples, epoxy impregnation emerged as a promising method for enhancing PLA/WF composite mechanical properties in the IM process, offering valuable insights for composite material development.

An Unprecedented [BO2]-Based Deep-Ultraviolet Transparent Nonlinear Optical Crystal by Superhalogen Substitution.

Solid-state structures with the superhalogen [BO2]- have thus far only been observed with a few compounds whose syntheses require high reaction temperatures and complicated procedures, while their optical properties remain almost completely unexplored. Herein, we report a facile, energy-efficient synthesis of the first [BO2]-based deep-ultraviolet (deep-UV) transparent oxide K9[B4O5(OH)4]3(CO3)(BO2) ⋅ 7H2O (KBCOB). Detailed structural characterization and analysis confirm that KBCOB possesses a rare four-in-one three-dimensional quasi-honeycomb framework, with three π-conjugated anions ([BO2]-, [BO3]3-, and [CO3]2-) and one non-π-conjugated anion ([BO4]5-) in the one crystal. The evolution from the traditional halogenated nonlinear optical (NLO) analogues to KBCOB by superhalogen [BO2]- substitution confers deep-UV transparency (<190 nm), a large second-harmonic generation response (1.0×KH2PO4 @ 1064 nm), and a 15-fold increase in birefringence. This study affords a new route to the facile synthesis of functional [BO2]-based oxides, paving the way for the development of next-generation high-performing deep-UV NLO materials.

Exploration and Frontier of Coal Spontaneous Combustion Fire Prevention Materials

Mine fires have always been one of the disasters that restrict coal mining in China and endanger the life safety of underground workers. The research and development of new fire prevention materials are undoubtedly important to ensure the safe and efficient production of modern mines. At present, the main inhibiting materials used are grout material, inert gas, retarding agent, foam, gel, and so on. In order to explore the current situation of coal spontaneous combustion (CSC) fire prevention, the existing fire prevention materials were reviewed and prospected from three aspects: physical, chemical, and physicochemical inhibition. The results show that, at present, most of the methods of physicochemical inhibition are used to inhibit CSC. Antioxidants have become popular chemical inhibitors in recent years. In terms of physical inhibition, emerging biomass-based green materials, including foams, gels, and gel foams, are used to inhibit CSC. In addition, CSC fire-fighting materials also have shortcomings, including incomplete research on the mechanism of material action, poor stability of inhibitory properties, low efficiency, and economic and environmental protection to be improved. The future research direction of fire-fighting materials will be based on theoretical experiments and numerical simulation to study the mechanism and characteristics of CSC and develop new directional suppression materials with physicochemical synergies. These findings have extremely important implications for improving materials designed to prevent CSC.