Search Results (6,092)

5-Methoxymethyl-2-furfural (MMF) serves as a crucial biobased platform molecule that can be transformed into various high-value chemicals and biobased polyester monomers. However, the current production of MMF still faces several challenges, such as low yield and prolonged reaction time. In this study, we prepared a series of amide-modified strongly acidic resin catalysts and discovered that they have a higher efficiency in converting fructose to prepare MMF in 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl) and methanol. Among the synthesized catalysts, DB757-NMP demonstrated superior performance, achieving an MMF yield of approximately 61.5% under the optimized conditions, with a combined yield of HMF and MMF reaching about 66.6%. The catalyst formation mechanism was analyzed using FTIR, and NMR, confirming the transformation of proton between NMP and the sulfonic acid groups of the resin, which collectively promoted the conversion of fructose to MMF. In addition, we investigated main reasons for catalyst deactivation and successfully restored catalytic activity through regeneration. The regenerated catalyst could be reused for three times with only a slight decrease in MMF yield. The results suggested that DB757-NMP is a more sufficient and recyclable catalyst for the production of MMF from fructose. This work presented a simple and environmentally benign approach for the synthesis of MMF. Full article

The aim of this research was to assess the effects of different adhesive surface treatment protocols using universal adhesives on the shear bond strength (SBS) between a Vita Enamic and resin composite, as well as to analyze the associated failure modes. Eighty Vita Enamic ceramics were prepared, thermocycled, and randomly allocated into eight experimental groups following silane coupling agent pretreatment and adhesive system: Single Bond 2 (SB), silane + SB, Scotchbond Universal Plus (SBP), silane + SBP, Beautibond Xtreme (BEX), silane + BEX, Tetric N-Bond Universal (TUB), and silane + TUB. All specimens were etched with 9% hydrofluoric acid prior to adhesive application. Resin composites were bonded to the treated surfaces and subjected to SBS analysis using a universal testing device. Failure modes were performed under a stereomicroscope. Data were statistically determined using one-way ANOVA and Tukey’s post hoc test (α = 0.05). Statistically significant differences in SBS were indicated among the groups (p < 0.05). In the result, the SB (13.96 ± 2.34 MPa) and TUB (12.39 ± 2.91 MPa) groups exhibited the lowest SBS values and exclusively adhesive failure modes. Groups treated with silane and/or silane-containing universal adhesives (Sl + SB; 18.42 ± 3.11 MPa, SBP; 19.01 ± 2.62 MPa, BEX; 19.20 ± 2.96 MPa and Sl + TUB; 18.16 ± 2.82 MPa) demonstrated significantly higher SBS. The highest SBS values were achieved in the silane + SBP (24.53 ± 2.66 MPa) and silane + BEX (25.12 ± 2.74 MPa) groups, which were statistically comparable to each other and superior to all other groups. These groups also showed increased proportions of mixed and cohesive failures, indicating improved interfacial integrity. In conclusion, the SBS between Vita Enamic and the resin composite was significantly influenced by surface pretreatment and adhesive composition. Hydrofluoric acid etching combined with silane coupling agent pretreatment and silane coupling agent-containing universal adhesives provided the highest bond strength, supporting a multimodal strategy for the reliable repair of Vita Enamic restorations. Full article

Although the replication mechanism of the F plasmid and its regulatory strategies have been addressed in several studies, a comprehensive understanding of these processes remains incomplete. In this work, we present new observations that contribute to refining the current model of F plasmid replication control. In this work, the results indicate that plasmid copy number control in both the F plasmid and its derivatives is consistent with two previously proposed mechanisms: the titration model and the loop formation model. In both cases, the intracellular concentration and functional state of the RepE protein appear to play a central role. Consistent with earlier reports, the data of this study support the conclusion that the RepE monomer functions as the active replication initiator. Importantly, the transcriptional analyses suggest that not only RepE dimers but also monomers contribute to autoregulatory control of repE expression. These findings support a model in which the monomer–dimer equilibrium of RepE shapes both replication initiation and transcriptional autoregulation of the F plasmid. Full article

Objective: The biocompatibility of adhesive systems is essential for the long-term success of restorative dental procedures due to their close proximity to dentin and pulpal tissues. This study aimed to evaluate the cytotoxic effects of adhesive systems with different pH values on L929 mouse fibroblast cells under in vitro conditions. Materials and Methods: Four commercially available adhesive systems with different pH values—All-Bond Universal, G-Premio Bond, Tokuyama Bond Force II, and Clearfil Universal Bond Quick—were evaluated. Cytotoxicity was assessed using the MTT assay at four different concentrations (0.1%, 0.01%, 0.001%, and 0.0001%) and three incubation periods (24, 48, and 72 h). Cell viability data were analyzed using two-way analysis of variance followed by Bonferroni post hoc tests. Cytotoxicity was interpreted according to ISO 10993-5 criteria. Results: All adhesive systems exhibited concentration-dependent cytotoxicity, with significant reductions in cell viability observed only at the highest concentration (0.1%). At lower concentrations, no cytotoxic effects were detected. Despite having the highest pH value, All-Bond Universal consistently demonstrated the lowest cell viability. In contrast, Tokuyama Bond Force II showed the most favorable cytocompatibility profile, with relatively higher cell viability values over time. Morphological analysis supported the quantitative findings, revealing pronounced cellular alterations at high concentrations and preserved fibroblastic morphology at lower concentrations. Conclusions: adhesive systems demonstrate cytotoxic effects in a concentration-dependent manner, and pH alone is insufficient to predict their biocompatibility. Monomer composition and formulation characteristics appear to play a more critical role in determining cytotoxic behavior. These findings emphasize the importance of appropriate adhesive handling and isolation techniques to minimize tissue exposure and enhance clinical safety. Full article

The textile industry faces significant challenges regarding the need for textile waste recycling. This study investigates the feasibility of alkaline hydrolysis assisted by alcoholic co-solvents, such as ethanol, for recycling polyester/cotton blend textiles. Ethanol-assisted alkaline hydrolysis under mild conditions enabled almost complete depolymerisation of polyester, allowing the recovery of its monomers, terephthalic acid and ethylene glycol, which may be used to produce new polyester fibre. However, the treatment was found to adversely affect the properties of the cotton fibres, resulting in a recycled material of lower quality and functionality than the original material. In particular, a significant change in the structure of the cotton fibre was observed, namely, the transformation of cellulose I into cellulose II, as confirmed by FTIR analysis, along with a decrease in both the degree of polymerization and tensile strength, especially at an ethanol/water ratio of 40/60. Hence, alcohol-assisted alkaline hydrolysis is advisable for the chemical recycling of polyester, but it presents limitations when cotton fibres are also present. Full article

Solid polymer electrolytes (SPEs) hold great potential in high-safety energy storage but face two key bottlenecks: low room-temperature ionic conductivity and insufficient mechanical strength. This study proposes a synergistic optimization strategy of “long-carbon-chain regulation of polymer microstructure combined with porous polyimide (PI) support”. A linear random copolyester, poly(1,3-propylene-co-1,4-butylene succinate-co-sebacate) (PBPSS), was synthesized via melt polycondensation using 1,3-propanediol, 1,4-butanediol, succinic acid, and sebacic acid as monomers. Subsequently, the PBPSS-75 composite electrolyte was prepared with this copolyester as the matrix and porous PI as support. Results show that long-carbon-chain sebacic acid effectively regulates polymer segment flexibility and free volume, synergistically enhancing ionic conductivity and interfacial mechanical stability with lithium metal. Experimental data indicate that PBPSS-75 composite electrolyte exhibits an ionic conductivity of up to 4.25 × 10⁻⁵ S cm⁻¹ (30 °C), a lithium-ion transference number of 0.81, and an electrochemical stability window of 4.48 V (vs. Li/Li⁺). In LiFePO₄//Li batteries, it maintains nearly 100% capacity retention after 300 cycles at 0.5 C, and achieves stable cycling for over 800 h in lithium symmetric cells. This study confirms that the combined strategy effectively addresses the conductivity-mechanical property trade-off of SPEs, providing theoretical guidance and technical reference for high-performance solid-state battery material design. Full article

Biflavonoids are natural or pseudo-natural polyphenolic compounds formed by linking two flavonoid monomers via different bonds. Their unique dimeric structure endows them with broad-spectrum biological activities, establishing them as a core focus in drug development. However, the extremely low abundance and high structural similarity of natural biflavonoids present significant challenges. Consequently, synthetic technology has become a solution to overcome bottlenecks in supplements. The approaches involving chemical synthesis, emerging synthetic strategies, and biosynthesis are employed for the synthesis of different biflavonoids. In this review, we systematically summarize the application of diverse synthetic methods and clarify the extensive biological activities of the biflavonoids. Furthermore, we discuss the current challenges in biflavonoid synthesis and biological applications, as well as providing an outlook on future directions. Full article

A hybrid material based on the copolymerization of EDOT (3,4-ethylenedioxythiophene) and Py (pyrrole), 1:1 monomer ratio, onto multi-walled carbon nanotubes (MWCNTs) was synthesized through a multistep functionalization approach. The resulting P(EDOT-co-Py)@MWCNT hybrid, poly(3,4-ethylenedioxythiophene-co-pyrrol)@MWCNT hybrid, was characterized by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). These characterizations confirmed the successive functionalization steps, the effective anchoring of the monomers, and the subsequent formation of the copolymer. Transmission electron microscopy (TEM) images revealed a homogeneous polymer coating along the nanotube surface while preserving the structural integrity of the MWCNTs throughout the functionalization and polymerization processes. The P(EDOT-co-Py)@MWCNT hybrid was evaluated as an active electrode material for aluminum-ion storage in an aqueous aluminum sulfate electrolyte. The system exhibited two distinct charge-storage mechanisms: at high current densities, proton surface adsorption dominated, whereas at lower rates, a faradaic contribution associated with polymer chain redox activity and the reversible extraction/insertion of Al³⁺ became prevalent. The hybrid electrode delivered high specific capacities, reaching 200.6, 106.3, and 44.3 mAh g⁻¹ at 0.10, 0.25, and 0.50 A g⁻¹, respectively. These values are comparable to—or even exceed—those reported for similar cathodic materials designed for Al³⁺ storage, highlighting P(EDOT-co-Py)@MWCNT hybrid as a highly promising cathode candidate for aqueous aluminum-ion energy-storage systems. Full article

Eupalinolide A (EA, Z-configuration) and Eupalinolide B (EB, E-configuration) are cis-trans isomeric sesquiterpenoid monomers isolated from Eupatorium lindleyanum DC. (Asteraceae). Although these compounds display anti-inflammatory and anti-tumor activities, their metabolite profiles and possible hepatotoxicity remain largely unknown. This study aimed to investigate the metabolic profiles of EA and EB in liver microsomes and clarify whether they undergo metabolic activation or detoxification. EA and EB were metabolically profiled in human liver microsomes (HLMs) via UPLC-Q-TOF-MS. A HepG2-HLM co-culture system was used to compare the hepatocyte toxicity of parent compounds and their hydrolysis, oxidation, and hydrolysis–oxidation metabolites, thus evaluating their metabolic detoxification pathways. Sixteen metabolites of EA and 19 of EB were identified, with hydrolysis being the predominant metabolic pathway for both isomers. Both compounds showed low hepatocyte toxicity and underwent metabolic detoxification mainly via hydrolytic and oxidative pathways. Notably, hydrolysis metabolites had significantly lower toxicity than oxidative products in HepG2 cells. These results suggest that EA and EB could present a relatively low risk of in vivo hepatotoxicity, which provides useful information for understanding the metabolic behavior and safety profile of these bioactive sesquiterpenoids. Full article

The orthodontic landscape is currently witnessing a significant technological evolution with the emergence of direct 3D-printed aligners (DPAs), which promise to close the digital workflow loop by eliminating the geometric limitations and solid model waste inherent to traditional thermoformed clear aligners (TCAs). This review provides a comprehensive analysis of the material science governing this transition from inert thermoplastic sheets to reactive photocurable resins. We explore the fundamental chemistry of DPA materials, and the pivotal role of post-processing in ensuring mechanical integrity and biocompatibility. Beyond passive mechanics, this review highlights preclinical research in functional material engineering, detailing how experimental DPAs are being investigated for the integration of antibacterial agents, remineralization fillers, and drug delivery systems. Furthermore, we evaluate the limited but emerging clinical data on DPAs, contrasting their shape-memory properties and force delivery profiles with conventional appliances, while critically addressing emerging safety concerns regarding monomer elution and microplastic generation. We conclude that while DPA technology offers superior dimensional control, comprehensive life cycle assessments and long-term in vivo trials are essential to fully substantiate their clinical efficacy, overall sustainability, and potential as advanced orthodontic appliances. Full article

Polymer electrolytes have been explored as an alternative to conventional aqueous electrolytes in zinc-ion batteries, particularly for flexible and wearable applications. Despite the increasing interest in polymer electrolyte-based zinc-ion batteries (ZIBs), their development is still in its early stages due to various challenges. In this study, we investigated three promising polymer electrolytes: CSAM (carboxyl methyl chitosan with acrylamide monomer), PAM (polyacrylamide monomer hydrogel electrolyte), and p-PBI (phosphate-doped polybenzimidazole solid electrolyte) with Zn(ClO₄)₂ and Zn(OTf)₂, as electrolytes for zinc-ion batteries. The p-PBI solid electrolyte showed high mechanical stability and improved resistance to short-circuiting during cycling. The presence of carboxyl groups in CSAM and the existence of O-H bonding facilitated ion movement, resulting in enhanced ionic conductivity and preventing dendrite formation. Incorporating these hydrogels with high-performance zinc salts, such as zinc triflate (Zn(OTf)₂), resulted in stable symmetric cell cycling over 4000 h with a uniform voltage profile under 1 mA/cm² and a low overpotential of around 53 mV cycling with CSAM. Rate-dependent full-cell testing showed that the PBI solid electrolyte delivers higher capacity retention at different current densities, whereas CSAM exhibits markedly better long-term stability, even at low voltages, owing to its effective dendrite suppression, which helps preserve cathode performance over extended cycling. Full article

Aliphatic polyesters, widely used in biomedicine due to their biocompatibility and biodegradability, are typically synthesized via the ring-opening polymerization (ROP) of cyclic esters. Although traditional metal catalysts are highly active, their biological toxicity limits their applications. Organocatalysts, particularly natural organic molecules, offer safer alternatives. We explored the ROP mechanisms of cyclic esters (L-Lactide (L-LA), ε-caprolactone (ε-CL), and δ-valerolactone (δ-VL)) catalyzed by phosphonium carboxybetaines (PCBs, (PhR)₃P⁺(CH₂)₂COO⁻, R = H(PCB), F(PCB-F) and OMe(PCB-OMe)) through density functional theory (DFT) computations. The DFT results revealed that the ROP of cyclic esters follows a bifunctional–cooperative activation mechanism, wherein the phosphonium moiety (Ph₃P⁺(CH₂)₂) activates the monomer via an extensive hydrogen-bonding interaction network, and the carboxylate (COO⁻) serves as a proton acceptor to enhance the nucleophilicity of the initiator phenylpropanol (PPA). In contrast, unsubstituted PCB exhibited the lowest energy barrier, being consistent with the highest catalytic activity among PCB derivatives observed experimentally. Moreover, a series of novel PCB derivatives (Ph₃P⁺(CH₂)_nCOO⁻, n = 3–6 (PCB1-PCB4)) were designed by regulating the carbon spacer length, and their catalytic performances were computationally tested. The designed catalyst PCB2 (Ph₃P⁺(CH₂)₄COO⁻) exhibited higher activity for the ROP of L-LA, attributed to providing sufficient flexibility to minimize deformation while improving proton-accepting capability. Similarly, PCB2 also demonstrated superior catalytic activity for δ-VL and the more challenging ε-CL monomer. This work not only clarifies the intrinsic catalytic nature of these zwitterionic organocatalysts, but also provides an effective strategy for the rational design of high-performance, metal-free catalysts for the synthesis of sustainable polyesters. Full article

Nenestatins (NENs) belong to benzo[b]fluorene-containing atypical angucyclines, a structurally diverse class of microbial natural products. Bioinformatic analysis of the NEN biosynthetic gene cluster (nes BGC) from the deep-sea sediment-derived Micromonospora echinospora SCSIO 04089 implicated Nes5 as an α/β hydrolase. The targeted inactivation of the nes5 gene led to the accumulation of five new analogs, NENs E–I (1–5), together with the known monomer homo-dehydrorabelomycin E (6). Their structures were elucidated by comprehensive spectroscopic analysis and electronic circular dichroism calculations. Notably, both NEN A and NEN B were absent in the Δnes5 mutant, indicating that Nes5 is essential for their biosynthesis; however, the exact function of Nes5 requires further exploration. Full article

Drought stress severely constrains plant growth and productivity. To mitigate water loss, plants primarily regulate stomatal aperture through the Abscisic acid (ABA) signaling pathway, where the Sucrose Nonfermenting 1-Related Protein Kinase 2 (SnRK2) family kinase Open Stomata 1 (OST1) acts as a central positive regulator. However, the upstream regulators that fine-tune OST1 activity remain incompletely characterized. Aliphatic Suberin Feruloyl Transferase (ASFT), a BAHD acyltransferase essential for suberin aromatic monomer biosynthesis, was previously uncharacterized regarding its function in leaves. Here, we report that ASFT negatively regulates drought tolerance in Arabidopsis thaliana by directly interacting with OST1 and inhibiting its autophosphorylation, thereby restricting stomatal aperture. Consistent with this, the asft mutant exhibited decreased water loss and enhanced survival under drought, whereas ASFT-overexpressing lines showed opposite phenotypes. BiFC, Co-IP and in vitro kinase assays confirmed that ASFT directly interacts with OST1 and suppresses its autophosphorylation, while dehydration-induced OST1 phosphorylation was elevated in the asft mutant. Genetic evidence confirmed that ASFT functions upstream of OST1. This study reveals a moonlighting role for this suberin biosynthetic enzyme in ABA signaling and provides a potential target for breeding drought-resistant crops. Full article

Kucha, a unique tea germplasm rich in theacrine, imparts its fresh leaves with a particularly bitter taste and multiple bioactivities. However, systematic studies on processed Kucha—especially white tea—remain limited. In this study, white teas were produced from two Yunnan Kucha accessions (YLKC1, YLKC2) and two conventional cultivars. Their quality characteristics and non-volatile metabolic profiles were systematically compared using sensory evaluation, targeted quantification and widely targeted metabolomics. Results indicated that Kucha white teas displayed pronounced bitterness, with YLKC1 presenting a richer, well-layered flavor, indicating promising quality potential. Targeted quantification demonstrated a remarkably high theacrine content (~30 mg/g) in Kucha white teas, whereas caffeine and several catechin monomers were significantly lower than those in conventional cultivars. Widely targeted metabolomic analysis identified 3376 non-volatile metabolites. PCA and OPLS-DA demonstrated a clear separation in metabolic profiles between Kucha and control groups. In total, 601 significantly differential metabolites were identified. Taste-driven annotation against ChemTastesDB revealed 17 known bitter compounds, 10 of which were significantly accumulated in Kucha white tea—including theacrine, theophylline, theobromine, L-arginine, neohesperidin, pinocembrin, kaempferol-3-O-(6”-malonyl)glucoside, fraxin, adenosine, and xanthine. Among these compounds, theacrine showed the highest upregulation (9.30-fold). In addition, several galloylated flavonoid glycosides also exhibited significant accumulation. KEGG enrichment analysis further indicated that flavonoid biosynthesis and caffeine metabolism were crucial pathways contributing to these metabolic differences. Collectively, these findings demonstrate that the characteristic bitterness of Kucha white tea arises from the coordinated accumulation of a specific set of bitter phytochemicals rather than a single compound and provide a prioritized panel of candidate compounds for flavor-oriented breeding and processing. Full article