Search Results (22)

The present investigation highlights the importance of evaluating the painting process on a composite material, namely the Kevlar validation process. Kevlar, a synthetic fabric, is well known for its remarkable strength and durability. Kevlar is used in the construction of spaceships and airplanes because it is lightweight and five times stronger than steel. This paper will present the methods for measuring paint layer thickness in accordance with EN ISO 2808:2019, confirming that organic coatings have fully cured, and coating thickness will be measured using magnetic currents. This study will also address the topic of determining liquid resistance. The protocols for manufacturing the Kevlar specimen are in accordance with ISO 2812-2:2018 using the water immersion method and structural testing. The investigation also demonstrates the progress of the framing test following immersion in Airbus PTP metal test tubes. Full article

Short- and medium-sized peptides have long been used as effective and versatile organocatalysts. In the early 80s, Inoue used diketopiperazines in the Strecker reaction, while Juliá and Colonna reported the epoxidation of chalcone catalyzed by poly-L-Ala. Since then, a variety of peptide-catalyzed reactions have been described. However, peptide synthesis typically implicates the use of toxic reagents and generates wastes; therefore, peptide recycling is expected to significantly improve the overall sustainability of the process. Easy recovery and recycling of peptide catalysts can be expediently attained by covalent binding, inclusion, or adsorption. In addition, immobilization can significantly accelerate the screening of new peptide catalysts. For these reasons, diverse supports have been tested, including natural or synthetic polymers, porous polymeric networks, inorganic porous materials, organic-inorganic hybrid materials, and finally metal–organic frame-works. Full article

Water pollution, driven by industrial wastewater, agricultural runoff, and domestic sewage, introduces organic pollutants (e.g., dyes and antibiotics) and heavy metal ions (e.g., Pb²⁺ and Cr(VI)), threatening ecosystems and human health. Although traditional water treatment technologies have now matured, they still have some deficiencies in terms of specific pollutants. Metal–organic frameworks (MOFs), particularly zeolite imidazole frame-67 (ZIF-67)—a cobalt-based MOF with high surface area, tunable pores, and robust chemical stability—show excellent adsorption capacity for pollutants and have emerged as promising candidates for water treatment due to their efficacy in adsorption, catalysis, and photocatalysis. This review examines ZIF-67’s synthesis, functionalization strategies, and applications in removing organic pollutants and heavy metals. It explores its mechanisms, composite designs, and recyclability, while highlighting challenges and future directions for developing efficient, sustainable water treatment technologies. Full article

Purpose: This study aims to investigate the disposal practices of optical materials in Portuguese Optical Centers. Methods: This study, conducted in the Portuguese Optical Centers across 18 districts and 308 municipalities, divided the country into 4 regions for analysis. Utilizing Google Forms^®, a survey targeting Optical Center managers and related professionals was disseminated via email from February to May 2023, comprising 30 questions across 6 sections, including optical and contact lenses, maintenance solutions, eyeglass frames, and recycling participation. Data analysis employed IBM SPSS^® Statistics v.27, using non-parametric tests for variable distribution. Ethical standards and privacy policies were strictly observed throughout the research process. Results: Findings indicated that there were significant differences in the final treatment of organic and mineral lenses. Organic lenses were placed in the yellow recycling bin (22.2%), while mineral lenses were placed in the green recycling bin (37.9%). In the case of contact lenses, regardless of the type (RGP, scleral lenses, conventional hydrogels, and silicone hydrogel lenses), the majority (>50%) were disposed of in general trash. Regarding eyeglass frames, there were no significant differences between mass and metal frames, mostly being discard in general waste (~30.0%). Conclusion: Approximately half of the surveyed Portuguese Optical Centers were not actively involved in recycling. This represents a missed opportunity for optometrists to play a role in enhancing recycling rates through patient education. Full article

Long-afterglow materials have a broad of applications in optoelectronic devices, sensors, medicine and other fields due to their excellent luminescent properties. The host-guest long-afterglow MOFs material combines the advantages of multi-component characteristics and the stability of MOFs, which improves its luminous performance and expands its other properties. This review introduces the classification, synthesis and application of host-guest MOFs materials with long afterglow. Due to their rigid frames and multi-channel characteristics, MOFs can load common guest materials including rare earth metals, organic dyes, carbon dots, etc. The synthesis methods of loading guest materials into MOFs include solvothermal synthesis, post-encapsulation, post-modification, etc. Those long-afterglow host-guest MOFs have a wide range of applications in the fields of sensors, information security and biological imaging. Full article

Cardiovascular diseases (CVDs) increasingly burden health systems and patients worldwide, necessitating the improved awareness of current treatment possibilities and the development of more efficient therapeutic strategies. When plaque deposits narrow the arteries, the standard of care implies the insertion of a stent at the lesion site. The most promising development in cardiovascular stents has been the release of medications from these stents. However, the use of drug-eluting stents (DESs) is still challenged by in-stent restenosis occurrence. DESs’ long-term clinical success depends on several parameters, including the degradability of the polymers, drug release profiles, stent platforms, coating polymers, and the metals and their alloys that are employed as metal frames in the stents. Thus, it is critical to investigate new approaches to optimize the most suitable DESs to solve problems with the inflammatory response, delayed endothelialization, and sub-acute stent thrombosis. As certain advancements have been reported in the literature, this review aims to present the latest updates in the coatings field for cardiovascular stents. Specifically, there are described various organic (e.g., synthetic and natural polymer-based coatings, stents coated directly with drugs, and coatings containing endothelial cells) and inorganic (e.g., metallic and nonmetallic materials) stent coating options, aiming to create an updated framework that would serve as an inception point for future research. Full article

Metal–organic frame (MOF) materials may have the advantages of a regular pore structure, large porosity, and large specific surface area, which could provide better catalytic activity, but they have some disadvantages in electrocatalysis. In contrast, carbon nanofibers (CNFs) prepared by electrospinning methods have good conductivity and stability. Therefore, this research aimed to generate MOF/CNFs composite materials to improve the electrochemical properties of MOF materials and apply them to the field of electrochemical sensing. This experiment was based on the preparation of straight unidirectional CNFs by an electrospinning method at 2000 RPM. The original method of preparing zeolitic imidazolate frameworks (ZIF-8) was improved and ZIF-8 was uniformly dispersed on the surface of CNFs to form a ZIF-8/CNF composite with a fiber diameter of about 0.10 to 0.35 µm. The specific surface area of the CNFs was about 42.28 m²/g, while that of the ZIF-8/CNF composite was about 999.82 m²/g. The specific surface area of the ZIF-8/CNF composite was significantly larger than that of CNFs. The GCE/ZIF-8/CNF electrode had an excellent electrochemical reaction, with an oxidation peak at about 216 μA, which proved that the ZIF-8/CNF composite material would have good catalytic activity and excellent electrochemical properties for the detection of nitrofurazone compared to other modified electrodes. Full article

Herein, we encapsulated modified silicon carbide nanoparticles utilizing a metal–organic backbone. E-SiC-FeZnZIF composites were successfully prepared via Fe doping. The catalysis activity of this bifunctional composite material was evaluated by the degradation of tetracycline (THC) and carbamazepine (CBZ) and the reduction of carbon dioxide (CO₂). Nano SiC has received widespread attention in advanced oxidation applications, especially in the catalytic activation of peroxymonosulfate (PMS). However, the inferior activity of SiC has severely restricted its practical use. In this study of dual functional composite materials, nano SiC was firstly etched under aqueous alkali. Then, zeolite imidazolate frame-8 (ZIF-8) was used for immobilization. The filling of the etched nano SiC with FeZnZiF was confirmed by SEM, XRD, FTIR, BET, and XPS analyses. In addition, E-SiC-FeZnZIF exhibited excellent catalytic activation of peroxymonosulfate (PMS) to oxidize water pollutants, which can degrade tetracycline hydrochloride (THC), achieving a removal rate of 72% within 60 min. Moreover, E-SiC-FeZnZIF exhibited a relatively high CO₂ reduction rate with H₂O. The yields of CO and CH₄ were 0.085 and 0.509 μmol g⁻¹, respectively, after 2 h, which are higher than that of 50 nm of commercial SiC (CO: 0.084 μmol g⁻¹; CH₄: 0.209 μmol g⁻¹). This work provides a relatively convenient synthesis path for constructing metal skeleton composites for advanced oxidation and photocatalytic applications. This will have practical significance in protecting water bodies and reducing CO₂, which are vital not only for maintaining the natural ecological balance and negative feedback regulation, but also for creating a new application carrier based on nano silicon carbide. Full article

Quinone organic materials are promising electrodes for the next lithium-ion batteries (LIBs) owing to their versatile molecular designs, high theoretical capacity, flexibility, sustainability, and environmental friendliness. However, quinone organic electrode materials can easily dissolve in organic electrolytes during the cycling process, which leads to the decay of capacity and poor cycling stability. Here, two metal-organic frames (MOFs), one-dimensional (1D) linear structural anthraquinone-2,3-dicarboxylate zinc coordination polymer (ZnAQDC) and two-dimensional (2D) structural anthraquinone-2,3-dicarboxylate manganese coordination polymer (MnAQDC), are synthesized by using anthraquinone 2,3-dicarboxylic acid, zinc acetate, and manganese acetate in a simple hydrothermal reaction. The formed 1D and 2D structures facilitate the insertion and extraction of lithium ions in and from carbonyl groups of anthraquinone. When MnAQDC is used as cathodes for LIBs, MnAQDC electrodes show an initial discharge capacity of ~63 mAh g⁻¹ at 50 mA g⁻¹. After 200 cycles, the MnAQDC electrode still maintains the specific capacity of ~45 mA h g⁻¹, which exhibits good cycle stability. the ZnAQDC electrode displays a initial discharge capacity of ~85 mA h g⁻¹ at 50 mA g⁻¹, and retains the specific capacity of ~40 mA h g⁻¹ after 200 cycles, showing moderate cyclic performance. The lithium-inserted mechanism shows that lithium ions are inserted and extracted in and from the carbonyl groups, and the valences of the Zn and Mn ions in the two MOFs do not change, and coordination metals do not contribute capacities for the two MOFs electrodes. The strategy of designing and synthesizing MOFs with 1D and 2D structures provides guidance for suppressing the dissolution and improving the electrochemical performance of quinone electrode materials. Full article

The hydrogen-bonded organic frameworks (HOFs) are a class of porous materials with crystalline frame structures, which are self-assembled from organic structures by hydrogen bonding in non-covalent bonds π-π packing and van der Waals force interaction. HOFs are widely used in environmental remediation due to their high specific surface area, ordered pore structure, pore modifiability, and post-synthesis adjustability of various physical and chemical forms. This work summarizes some rules for constructing stable HOFs and the synthesis of HOF-based materials (synthesis of HOFs, metallized HOFs, and HOF-derived materials). In addition, the applications of HOF-based materials in the field of environmental remediation are introduced, including adsorption and separation (NH₃, CO₂/CH₄ and CO₂/N₂, C₂H₂/C₂H_e and C_eH₆, C₂H₂/CO₂, Xe/Kr, etc.), heavy metal and radioactive metal adsorption, organic dye and pesticide adsorption, energy conversion (producing H₂ and CO₂ reduced to CO), organic dye degradation and pollutant sensing (metal ion, aniline, antibiotic, explosive steam, etc.). Finally, the current challenges and further studies of HOFs (such as functional modification, molecular simulation, application extension as remediation of contaminated soil, and cost assessment) are discussed. It is hoped that this work will help develop widespread applications for HOFs in removing a variety of pollutants from the environment. Full article

Two-dimensional metal-organic frameworks (MOFs) have shown great development po-tential in the field of lithium-sulfur (Li-S) batteries. In this theoretical research work, we propose a novel 3d transition metals (TM)-embedded rectangular tetracyanoquinodimethane (TM-rTCNQ) as a potential high-performance sulfur host. The calculated results show that all TM-rTCNQ structures have excellent structural stability and metallic properties. Through exploring different adsorption patterns, we discovered that TM-rTCNQ (TM = V, Cr, Mn, Fe and Co) monolayers possess moderate adsorption strength for all polysulfide species, which is mainly due to the existence of the TM-N₄ active center in these frame systems. Especially for the non-synthesized V-rCTNQ, the theoretical calculation fully predicts that the material has the most suitable adsorption strength for polysul-fides, excellent charging-discharging reaction and Li-ion diffusion performance. Additionally, Mn-rTCNQ, which has been synthesized experimentally, is also suitable for further experimental con-firmation. These findings not only provide novel MOFs for promoting the commercialization of Li-S batteries, but also provide unique insights for fully understanding their catalytic reaction mecha-nism. Full article

With the rapid development of urbanization and industrialization, water contamination has gradually become a big problem. Relevant studies show that adsorption is an efficient strategy to treat pollutants in water. MOFs are a class of porous materials with a three-dimensional frame structure shaped by the self-assembly of metal centers and organic ligands. Because of its unique performance advantages, it has become a promising adsorbent. At present, single MOFs cannot meet the needs, but the introduction of familiar functional groups on MOFs can promote the adsorption performance of MOFs on the target. In this review, the main advantages, adsorption mechanism, and specific applications of various functional MOF adsorbents for pollutants in water are reviewed. At the end of the article, we summarize and discuss the future development direction. Full article

The study aims to enhance our knowledge of the materials and techniques applied in the making of Russian, portable ecclesiastical paintings produced after the 16th century, and to evaluate a pilot, non-destructive, non-invasive, research methodology proposed for their examination. Based on research relating to the historical background of their production and distribution in the South, the availability of materials and the applied techniques, a non-destructive, non-invasive methodology is exploited to examine three triptychs and two polyptych side panels belonging to the collection of the Benaki Museum. As their small size and excellent state of preservation prohibit sampling, a study scheme based on visual examination, the implementation of a series of spectral imaging techniques (VIS, IRRFC, SWIR, UVL, RTI, X ray) and a non-invasive micro XRF analysis is tested. Fiber and wood-type identification are carried out microscopically. The collected information relates to the making of the frames and the supports, the design, the use of metal foils and pigments, the order of application of paint layers and the rendering techniques. Due to the non-destructive, non-invasive character of the procedure, organic constituents are not thoroughly examined. Use of an expected palette was confirmed, but the modelling proved rather sophisticated. Among the most interesting finds were the use of distinct pigment mixtures for the underpaints of the flesh parts and certain deviations from the expected rendering techniques. The methodology proved very effective in terms of its output, the global approach of the construction technique, the user-friendly application, the low cost and time consumption factors. Full article

Lanthanide hydrogen-bonded organic frameworks (LnHOFs) are recently emerging as a novel versatile class of multicomponent luminescent materials with promising potential applications in optics and photonics. Trivalent europium (Eu³⁺) incorporated polymeric hydrogen-bonded triazine frameworks (PHTF:Eu) have been successfully obtained via a facile and low-cost thermal pyrolysis route. The PHTF:Eu material shows a porous frame structure principally composed of isocyanuric acid and ammelide as a minor constituent. Intense red luminescence with high colour-purity from Eu³⁺ is obtained by exciting over a broad absorption band peaked at 300 nm either at room or low temperature. The triazine-based host works as excellent optical antenna towards Eu³⁺, yielding ~42% sensitization efficiency (η_sens) and an intrinsic quantum yield of Eu³⁺ emission (Φ_Eu) as high as ~46%. Temperature-dependent emission studies show that PHTF:Eu displays relatively high optical stability at elevated temperatures in comparison to traditional inorganic phosphors. The retrieved activation energy of 89 meV indicates that thermal quenching mechanisms are attributed to the intrinsic energy level structure of the metal-triazine assembly, possibly via a thermally activated back transfer to ligand triplet or CT states. Finally, by using an innovative approach based on excitation spectra, we demonstrate that PHTF:Eu can work as a universal primary self-referencing thermometer based on a single-emitting center with excellent relative sensitivity in the cryogenic temperature range. Full article

Machine learning approaches can drastically decrease the computational time for the predictions of spectroscopic properties in materials, while preserving the quality of the computational approaches. We studied the performance of kernel-ridge regression (KRR) and gradient boosting regressor (GBR) models trained on the isotropic shielding values, computed with density-functional theory (DFT), in a series of different known zeolites containing out-of-frame metal cations or fluorine anion and organic structure-directing cations. The smooth overlap of atomic position descriptors were computed from the DFT-optimised Cartesian coordinates of each atoms in the zeolite crystal cells. The use of these descriptors as inputs in both machine learning regression methods led to the prediction of the DFT isotropic shielding values with mean errors within 0.6 ppm. The results showed that the GBR model scales better than the KRR model. Full article