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The gut is colonized by many commensal microorganisms, and the diversity and metabolic patterns of microorganisms profoundly influence the intestinal health. These microbial imbalances can lead to disorders such as inflammatory bowel disease (IBD). Microorganisms produce byproducts that act as signaling molecules, triggering the immune system in the gut mucosa and controlling inflammation. For example, metabolites like short-chain fatty acids (SCFA) and secondary bile acids can release inflammatory-mediated signals by binding to specific receptors. These metabolites indirectly affect host health and intestinal immunity by interacting with the intestinal epithelial and mucosal immune cells. Moreover, Tryptophan-derived metabolites also play a role in governing the immune response by binding to aromatic hydrocarbon receptors (AHR) located on the intestinal mucosa, enhancing the intestinal epithelial barrier. Dietary-derived indoles, which are synthetic precursors of AHR ligands, work together with SCFA and secondary bile acids to reduce stress on the intestinal epithelium and regulate inflammation. This review highlights the interaction between gut microbial metabolites and the intestinal immune system, as well as the crosstalk of dietary fiber intake in improving the host microbial metabolism and its beneficial effects on the organism.

Vehicle sound package system plays a critical role in determining vehicle’s noise, vibration, and harshness (NVH) performance. With the advent of new energy vehicles, novel acoustic challenges arise in the absence of the masking effect provided by engine noise. The need for more efficient sound package is an important topic for both automotive Original Equipment Manufacturers (OEMs) and academic researchers. Despite the wealth of research on the sound package, a comprehensive review of the state-of-the-art has been lacking. This review aims to fill this gap by providing a concise and up-to-date overview of the various noise sources and transmission paths, functions, materials, components, and study approaches involved in the vehicle sound package technology. Vehicle sound package is fundamental in controlling the engine noise, road noise, and wind noise inside the vehicle, with functions that include sound absorption, sound insulation, damping, and sealing. To optimize these functions, an assortment of materials have been employed, from conventional options like foam and fiber to more innovative solutions like plastic and rubber, as well as functional materials and multilayer composites. To enhance vehicle sound package performance, both experimental and numerical methods, such as finite element analysis (FEA) and statistical energy analysis (SEA), artificial intelligence (AI)-driven optimization are employed in academic research, while the industrial development process often involves a more intricate and practical approach. This review also makes some recommendations for future research work in this area. It is expected that this review will provide useful information for further development of vehicle sound package technology.

Underwater sound absorption materials with a stable performance at various hydrostatic pressures are important for marine applications. However, most studies about underwater sound absorption materials only focused on the performance at atmospheric hydrostatic pressure, while ignoring the influence of various hydrostatic pressures. Aiming to improve the underwater sound absorption stability of a metamaterial at various hydrostatic pressures, different structures and a Nelder–Mead algorithm with an acoustic-structure fully coupled finite element method (FEM) model are developed to optimize the structure of the metamaterial at various hydrostatic pressures. In this numerical modeling, the metamaterial is a PDMS matrix embedded with periodic cylinders. Firstly, the effect of hydrostatic pressure on the metamaterial is evaluated in the frequency range [0, 8 kHz]. Secondly, different cases are designed to improve the underwater sound absorption stability at various hydrostatic pressures, including different cylinder radii, different distances between the air cylinder and the steel backing, and different void shapes. Then two layers of air and/or steel cylinders are introduced to further improve sound absorption performance under various hydrostatic pressures. The results indicate that PDMS with two layers of air cylinders have the optimal sound absorption stability performance under various hydrostatic pressures, which can be attributed to the top layer of air cylinders absorbing the main deformation. Lastly, the optimization algorithm significantly improves the sound absorption performance of the metamaterials at various hydrostatic pressures. This combination of an optimistic algorithm and FEM can guide the design of underwater sound absorption metamaterials at various hydrostatic pressures.

This review focuses on the recent advances in the synthesis of graphene quantum dots (GQDs) and their applications in drug delivery. To give a brief understanding about the preparation of GQDs, recent advances in methods of GQDs synthesis are first presented. Afterwards, various drug delivery-release modes of GQDs-based drug delivery systems such as EPR-pH delivery-release mode, ligand-pH delivery-release mode, EPR-Photothermal delivery-Release mode, and Core/Shell-photothermal/magnetic thermal delivery-release mode are reviewed. Finally, the current challenges and the prospective application of GQDs in drug delivery are discussed.

As a complex and persistent inflammatory bowel disease, the onset and progression of ulcerative colitis (UC) are closely associated with intestinal microbiota dysbiosis, host metabolic imbalance, and impaired intestinal barrier function. The traditional Chinese medicine (Sanqi) possesses multiple therapeutic properties, among which its anti-inflammatory effect is particularly remarkable. However, the specific molecular pathways through which exerts its anti-UC effects have not been fully elucidated. This study aims to clarify the efficacy and molecular mechanisms of extract in a mouse model of UC. A colitis model was established by inducing UC in ICR mice using dextran sulfate sodium (DSS). The experimental animals were divided into four groups: normal control group (CON), normal administration group (CONSQ), DSS-induced model group (DSS), and DSS-induced administration group (DSSSQ). The CONSQ and DSSSQ groups received oral gavage of 200 mg/kg extract. The evaluation indicators included the disease activity index, histopathological examination of colon tissue, expression of key intestinal barrier proteins, analysis of intestinal microbiota structure, and metabolomic testing of fecal samples. Treatment with extract repaired the damaged intestinal barrier, as evidenced by increased expression levels of Claudin-1, Occludin, ZO-1, and MUC-2 proteins. Simultaneously, the extract favorably modulated the structure of the intestinal microbiota, specifically by increasing the Firmicutes/Bacteroidetes ratio and enriching probiotic genera (such as Bifidobacterium and Lactobacillus). Furthermore, the extract significantly reduced the levels of characteristic metabolites (such as LysoPI and Etamiphylline). Correlation analysis based on multi-omics data revealed an interactive regulatory network centered on the intestinal microbiota, host metabolites, and intestinal barrier integrity, indicating that extract alleviates the pathological process of UC through a multi-target, synergistic approach. The results of this study demonstrate that extract exerts its therapeutic effects on UC by repairing the intestinal barrier, modulating the composition of the intestinal microbiota, and influencing the host metabolic profile. Multi-omics correlation analysis further revealed the central role of the microbiota-metabolite-barrier axis in the anti-UC effects of , providing strong evidence for its multi-target synergistic mechanism. These findings lay the foundation for a deeper understanding of the pharmacological mechanisms of Panax notoginseng in UC treatment and support its further development as a potential therapeutic agent for UC.

The flame-retardant properties of polydimethylsiloxane (PDMS)/oxidised multi-walled carbon nanotubes (MWCNT–COOH) nanocomposite films were dispersed using a nonionic acrylate copolymer surfactant. The nanocomposite films were prepared by spin coating and characterised using SEM, quasi-elastic cold-neutron scattering, TGA–FTIR, cone calorimetry, and LOI. The PDMS/surfactant/MWCNT–COOH (PSM) nanocomposite displayed superior flame-retardant performance compared to materials containing only surfactant or MWCNT–COOH. The peak heat release rate, the peak smoke production rate, total smoke release rate, carbon monoxide, and carbon dioxide production from PSM were 42, 47, 18, 28, and 47% less than the PDMS control. The LOI results for PSM exhibited a value of 32% with respect to 25% for the PDMS. PSM suppresses the smoke emission and inhibits penetration of the air reacting with the gas volatiles of the material. These new nanocomposites provide a valuable improvement in flame-retardant capabilities by physical barrier effect compared to other PDMS polymer materials. Graphic abstract

The high thermal conductivity of graphene and few-layer graphene undergoes severe degradations through contact with the substrate. Here we show experimentally that the thermal management of a micro heater is substantially improved by introducing alternative heat-escaping channels into a graphene-based film bonded to functionalized graphene oxide through amino-silane molecules. Using a resistance temperature probe for in situ monitoring we demonstrate that the hotspot temperature was lowered by ∼28 °C for a chip operating at 1,300 W cm −2 . Thermal resistance probed by pulsed photothermal reflectance measurements demonstrated an improved thermal coupling due to functionalization on the graphene–graphene oxide interface. Three functionalization molecules manifest distinct interfacial thermal transport behaviour, corroborating our atomistic calculations in unveiling the role of molecular chain length and functional groups. Molecular dynamics simulations reveal that the functionalization constrains the cross-plane phonon scattering, which in turn enhances in-plane heat conduction of the bonded graphene film by recovering the long flexural phonon lifetime. The high thermal conductivity of graphene is considerably reduced when the two-dimensional material is in contact with a substrate. Here, the authors show that thermal management of a micro heater is improved using graphene-based films covalently bonded by amino-silane molecules to graphene oxide.

Molybdenum disulfide (MoS2) is one of the most important two-dimensional materials after graphene. Monolayer MoS2 has a direct bandgap (1.9 eV) and is potentially suitable for post-silicon electronics. Among all atomically thin semiconductors, MoS2’s synthesis techniques are more developed. Here, we review the recent developments in the synthesis of hexagonal MoS2, where they are categorized into top-down and bottom-up approaches. Micromechanical exfoliation is convenient for beginners and basic research. Liquid phase exfoliation and solutions for chemical processes are cheap and suitable for large-scale production; yielding materials mostly in powders with different shapes, sizes and layer numbers. MoS2 films on a substrate targeting high-end nanoelectronic applications can be produced by chemical vapor deposition, compatible with the semiconductor industry. Usually, metal catalysts are unnecessary. Unlike graphene, the transfer of atomic layers is omitted. We especially emphasize the recent advances in metalorganic chemical vapor deposition and atomic layer deposition, where gaseous precursors are used. These processes grow MoS2 with the smallest building-blocks, naturally promising higher quality and controllability. Most likely, this will be an important direction in the field. Nevertheless, today none of those methods reproducibly produces MoS2 with competitive quality. There is a long way to go for MoS2 in real-life electronic device applications.

The effect of varying the weight percentage composition (wt.%) of low-cost expandable graphite (EG), ammonium polyphosphate (APP), fibreglass (FG), and vermiculite (VMT) in polyurethane (PU) polymer was studied using a traditional intumescent flame retardant (IFR) system. The synergistic effect between EG, APP, FG, and VMT on the flame retardant properties of the PU composites was investigated using SEM, TGA, tensile strength tests, and cone calorimetry. The IFR that contained PU composites with 40 wt.% EG displayed superior flame retardant performance compared with the composites containing only 20 w.t.% or 10 w.t.% EG. The peak heat release rate, total smoke release, and carbon dioxide production from the 40 wt.% EG sample along with APP, FG, and VMT in the PU composite were 88%, 93%, and 92% less than the PU control sample, respectively. As a result, the synergistic effect was greatly influenced by the compactness of the united protective layer. The PU composite suppressed smoke emission and inhibited air penetrating the composite, thus reducing reactions with the gas volatiles of the material. SEM images and TGA results provided positive evidence for the combustion tests. Further, the mechanical properties of PU composites were also investigated. As expected, compared with control PU, the addition of flame-retardant additives decreased the tensile strength, but this was ameliorated with the addition of FG. These new PU composite materials provide a promising strategy for producing polymer composites with flame retardation and smoke suppression for construction materials.

Procrastination is a key factor affecting college students' academic efficiency and physical and mental health. Factors such as digital culture, academic patterns, and economic pressures make students more prone to self-management difficulties, with procrastination becoming increasingly prominent. As an effective means of promoting physical and mental well-being, the relationship between physical exercise and procrastination warrants in-depth exploration. This study employs a cross-sectional survey design to examine the relationship between physical exercise and procrastination among college students, while testing the chained mediating effects of time management tendencies and mobile phone dependency. Methodologically, questionnaires were administered to 866 college students using the Physical Exercise Level Scale, General Procrastination Scale, Time Management Ttendencies Scale, and Mobile Phone Dependency Scale. Structural equation modeling analyzed variable relationships, while Bootstrap sampling verified the significance of mediating effects. Results revealed: ① Physical exercise was significantly negatively correlated with procrastination behavior; ② Physical exercise not only directly predicted procrastination behavior but also influenced it through the mediating effects of time management tendencies and mobile phone dependency; ③ Time management tendencies and mobile phone dependency exert a chain-mediating effect between physical exercise and procrastination. Findings indicate that physical exercise can indirectly alleviate procrastination among college students by enhancing time management tendencies and reducing mobile phone dependency. However, as this study employs a cross-sectional design, causal inferences should be interpreted with caution. Future research is recommended to adopt longitudinal or experimental designs to further validate causal mechanisms.