Search Results (65,330)

A lightweight composite that simultaneously exhibits high strength and excellent thermal insulation is of great interest for thermal protection applications. In this study, dimensionally stable needled quartz fiber felt-reinforced phenolic aerogel composites were prepared using vacuum impregnation, sol–gel, and ambient pressure drying. The composites exhibit a multiscale porous structure formed by interconnected nanometer polymer skeletons and micronscale fibers. By regulating the thermoplastic phenolic resin concentration in the precursor solution, the pore structure of the material was refined; the average particle diameter reduced from 99.76 nm to 38.91 nm, and the average pore diameter decreased from 216.79 nm to 49.53 nm. At a phenolic resin concentration of 25%, the composite exhibits outstanding thermal insulation and mechanical properties: a low thermal conductivity of 0.0646 W·m⁻¹·K⁻¹ at room temperature, with a mere 19.5 °C temperature rise on the sample backside after 1800 s heating at 200 °C, and compressive strengths of 7.70 MPa in the XY-direction and 3.87 MPa in the Z-direction (at 10% strain). X-ray micro-CT characterized the internal structural evolution during loading, revealing a failure mechanism dominated by fiber buckling. Theoretical models and experimental data were used to analyze and quantify the contribution rates of gas and solid heat conduction in NQF/PR aerogel composites, with solid conduction accounting for over 80%. Combined with microstructural evolution, the mechanism for the high thermal insulation efficiency of NQF/PR aerogel composites was elucidated. This study prepared NQF/PR aerogel composites with promising application potential. By systematically evaluating their compressive behavior and quantifying the respective contributions of gas and solid conduction, this work provides a methodological framework to guide the rational design of similar aerogel composites. Full article

This study investigates early-age cracking in the inclined bottom slabs of a 37.6 m wide PK-section concrete box girder during winter cantilever construction. A numerical method considering non-uniform material property development based on equivalent age was established. The method was validated by synchronous temperature and strain monitoring. The validated program was then used to analyze cracking causes and optimization measures. Results indicated that 3 days after casting, the maximum difference in equivalent age exceeded 7 days. Differences in elastic modulus and strength reached 30% and 34%, respectively, showing significant material non-uniformity. The restraint from completed segments was the primary cause of cracking. The total stress at the crack location was 5.5 MPa, with a 95% cracking probability. The ratio of thermal to shrinkage stress was 3.6:1. In summer, both total stress and strength increased, resulting in a similar cracking probability. Reducing the placing temperature decreased thermal stress by 0.13 MPa/°C in both seasons but had little effect on shrinkage. A 3 °C reduction lowered the cracking probability by 5–15%. Adding prestressed tendons to the bottom slab reduced total stress to 3.2 MPa and cracking probability to 37%, significantly mitigating cracking risk. Full article

Polyvinyl alcohol (PVA) fibers are commonly added to fiber-reinforced geopolymer composites (FRGC) to enhance their properties; however, systematic research on the dynamic mechanical properties of polyvinyl alcohol fiber-reinforced geopolymer composites (PVA-FRGC) is still required. In this study, an orthogonal experimental design was adopted to investigate the effects of the fly ash/slag ratio, fiber length, and fiber volume content on the dynamic mechanical properties (dynamic compressive strength, fragmentation degree, and energy absorption capacity) of PVA-FRGC. A split Hopkinson pressure bar (SHPB) was used to test the dynamic mechanical properties of the material. The results indicate that the fly ash/slag ratio, fiber length, and fiber volume content all exert significant effects on the dynamic compressive strength and energy absorption capacity of PVA-FRGC. The addition of PVA fibers significantly improves the dynamic compressive strength of PVA-FRGC, which reaches 157.52 MPa, 183.26 MPa, and 210.68 MPa under three different strain rates ranging from 75.4 s⁻¹ to 179.6 s⁻¹, respectively. Although the energy absorption capacity of PVA-FRGC is not significantly improved, the integrity of the specimens after fragmentation is remarkably enhanced. Specifically, under the three load levels, the average particle sizes of PVA-FRGC are 241.43%, 245.04%, and 127.80% higher than those of plain geopolymers, respectively. Considering the comprehensive dynamic mechanical properties, a fly ash/slag ratio of 5:5, a fiber length of 9 mm, and fiber volume content of 2.0% can be regarded as the local optimal mix proportion. Full article

Photosynthesis is of pivotal significance to the growth, development, and survival of plants. The conservation of endangered plant species represents a significant challenge within the broader context of biodiversity conservation. Analysis of the photosynthetic, physiological, and ecological characteristics of endangered plants is of significant value in understanding their survival mechanisms under adverse conditions, and can also provide key scientific support for the development of effective conservation measures. This study selected one-year-old Michelia guangdongensis seedlings to measure diurnal photosynthetic variations across different asexual lines. Using entropy-weighted TOPSIS evaluation and statistical analysis, we aimed to investigate photosynthetic differences among asexual lines and their relationship with environmental factors, thereby revealing the physiological characteristics of photosynthesis in M. guangdongensis seedlings. The results showed that the daily net photosynthetic rate variation of asexual lines CG3 and 1 of M. guangdongensis had asymmetric double-peak curves. Moreover, strains 9073, 8898, 8812, and 5 showed single-peak curves. Leaf transpiration rate (Trmmol) and CO₂ concentration (Ca) pathway analysis indicated these as the primary factors influencing the net photosynthetic rate of M. guangdongensis, with effective values of 1.17 and 0.9, respectively. TOPSIS entropy-weighted analysis indicated that the Ci values for CG3 and Leaf 1 exceeded 0.7, which indicated strong photosynthetic capacity. Additionally, the underside of the leaves exhibited superior coloration, thereby enhancing their ornamental value. This study provides a scientific basis and practical guidance for the breeding of asexual lines of M. guangdongensis. Full article

Exploring effective training methods to reliably trigger scoring in electronic protective gear is a significant challenge faced by coaches and athletes, and it constitutes a critical research direction that urgently demands scientific exploration. To improve the scientific precision of daily Taekwondo training and enhance competitive performance more efficiently and to improve the effectiveness of daily Taekwondo training and enhance competitive performance, a hydrogel-based flexible pressure-sensing film was developed. This film would enable traditional Taekwondo protective gear with electronic sensing capabilities via a simple adhesion method. By attaching a low-cost, high-precision, and appropriately flexible gel-based pressure-sensing film to conventional protective gear through a straightforward adhesion approach, it can attain sensing performance comparable to that of specialized competition-grade electronic protective gear. This innovation will provide technological support for advancing the scientific rigor of Taekwondo training in China. This study focuses on the design and development of high-strength, high-toughness ionic hydrogels, offering technical backing for the creation of flexible pressure-sensing films tailored for Taekwondo applications. Full article

The genus Psiadia (Asteraceae), widely distributed in Madagascar and the Mascarene Islands (Mauritius, La Réunion, Rodrigues), is traditionally used to treat bronchitis, asthma, colds, abdominal pain, and other inflammatory disorders. However, few studies have scientifically validated these traditional medicinal uses. To assess P. dentata as a valuable source of bioactive natural products, a combined ¹H NMR-based metabolomic, molecular networking, and phytochemical study was conducted. Multivariate analysis (PLS-DA) of crude extracts from Psiadia species collected on Reunion Island enabled rapid discrimination of active extracts from P. dentata and revealed two methoxylated flavonoids and one coumarin as metabolites correlated with its antiplasmodial and anti-inflammatory activities. Additionally, UHPLC-DAD-ESI-QTOF-MS/MS molecular networking approach enabled detailed chemical profiling of this species, allowing the annotation of 25 compounds (1–25) in this species. Subsequent phytochemical investigation of P. dentata leaves led to the isolation and identification of 25 metabolites, including nine new diterpenes (26–34), one new coumarin (35), and 15 known compounds (1–8, 11, 18, 19 and 36–39) from the diterpenoid, flavonoid, and coumarin families. The structures of the new compounds were elucidated using spectroscopic methods, including extensive 1D and 2D NMR and HRESIMS analyses. Biological evaluation of the isolated compounds showed that compounds 1, 7, 26 and 27 showed antiplasmodial activity against Plasmodium falciparum (3D7 strain, IC₅₀ = 7.25–13.46 μM). Compounds 7, 26, 27, 31 and 32 inhibited nitric oxide production (IC₅₀ = 0.87–27.71 μM), indicating potential anti-inflammatory effects. Only compound 1 displayed moderate cytotoxicity against HepG2 and HT29 cancer cell lines (IC₅₀ = 25.67 and 18.35 μM, respectively). Full article

Background: Cupriavidus is an aerobic Gram-negative bacterium and a rare conditional pathogen that mainly infects immunocompromised patients or those undergoing invasive procedures. Methods: We present the case of a 70-year-old male with diabetes mellitus who developed septic shock following influenza A virus (IAV) pneumonia. Cupriavidus gilardii (C. gilardii) was identified in his blood and sputum samples. Through a literature review, we identified 31 reported cases of Cupriavidus infections. Clinical data, including demographic information, clinical characteristics, comorbidities, laboratory results, Cupriavidus species, treatment, and clinical outcomes, were collected. Results: Among these 32 patients (including our patient), 23 were male (71.9%) and 9 were female (28.1%). The median patient age was 32.5 (2.12–70) years. Most patients had relevant risk factors or comorbidities before Cupriavidus infection, including exposure to polluted environments and recent invasive procedures (68.9%). Among these cases, Cupriavidus pauculus was the most common strain, accounting for 56.3% of cases. The mortality rate was the highest for Cupriavidus pauculus infections. Conclusions: Cupriavidus is a rare opportunistic pathogen in patients with compromised immune function. Early identification of pathogen and timely treatment are crucial. When traditional microbiological detection methods encounter difficulties, gene sequencing can be used as an auxiliary diagnostic tool and can further predict drug resistance. Targeted anti-infection treatment is effective in most cases, but some severe infection cases may lead to death due to serious complications. Full article

Background: Early diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM) remains challenging. Although ECG and morphological abnormalities at diagnosis are well-described, their temporal evolution has not been systematically evaluated. This study characterized the prevalence and longitudinal progression of electrical and structural cardiac abnormalities preceding ATTR-CM diagnosis. Methods: We retrospectively analyzed patients with confirmed ATTR-CM evaluated at a specialist amyloidosis center between 2006 and 2023. Diagnosis was established by grade 2–3 myocardial uptake on 99mTc-DPD scintigraphy. Standard 12-lead ECGs and transthoracic echocardiograms were reviewed at diagnosis and at baseline, 3–5 years earlier. Results: Sixty-three patients (79% men; mean age 77 ± 8 years) were studied, including 33 (52%) with hereditary ATTR (ATTRv) and 30 (48%) with wild-type ATTR (ATTRwt). Overall, 95% had a NAC score ≤ 2, consistent with less advanced disease at diagnosis. During the prediagnostic phase, 79% of patients exhibited pathological ECGs. Non-specific ST–T abnormalities (40%), prolonged QTc (38%), left-axis deviation (35%), first-degree AV block (33%) and anterior infarction pattern (33%) were each observed in at least one-third of patients. From baseline to diagnosis, significant prolongation was observed in the PR interval (+26 ms), QRS duration (+11 ms), and QTc interval (+22 ms) (p < 0.001 for all), and a leftward shift observed in the electrical axis (−12.03°, p = 0.011). Low voltage was uncommon at both time points. Although interventricular septal thickness increased significantly (+3.42 mm; p < 0.001), left ventricular ejection fraction and dimensions were relatively stable. Conclusions: In this proof-of-concept study, electrical remodeling precedes functional changes and outperforms low voltages to raise clinical suspicion of ATTR-CM. Full article

Silver nanoparticles (AgNPs) are among the most widely used type of nanoparticles due to their antimicrobial properties. While their application in disease treatment is well established, less is known about their ecological effects after they are released into ecosystems, where they may affect microorganisms and disrupt ecological balance. A green synthesis using Sambucus nigra fruit extract was applied to prepare AgNPs of two sizes, and their interactions with Brevundimonas vesicularis USM1, Pseudarthrobacter oxydans USM2, Pseudomonas putida USM4, Escherichia coli ATCC 10536, Staphylococcus aureus ATCC 25923, and Pseudomonas aeruginosa ATCC 27853 were examined. The nanoparticles were characterized by UV–Vis, TEM, and DLS, and microbial growth was assessed using microplate assays and colony enumeration. No significant inhibition of E. coli ATCC 10536, S. aureus ATCC 25923, or P. aeruginosa ATCC 27853 was observed in the presence of small (22 nm) or large (66 nm) AgNPs. Growth inhibition occurred in P. oxydans USM2 and P. putida USM4 exposed to small AgNPs, and in B. vesicularis USM1, P. oxydans USM2, and P. putida USM4 exposed to large AgNPs. The strain-specific responses indicate a size-dependent impact on bacteria, suggesting potential effects on microbiome structure and function. This study provides insights supporting environmental risk evaluation and safer-by-design development of AgNP-based materials. Full article

The berberine derivative 13-(2-methylbenzyl)-berberine (BED) has been shown to inhibit the MexXY-OprM efflux system of Pseudomonas aeruginosa (PA), a key contributor to aminoglycoside resistance, by interacting with the inner membrane protein MexY at an allosteric pocket (ALP). To enhance binding efficacy, this study aims to identify novel chemical scaffolds that target the MexY allosteric pocket through an integrated computational strategy. In this work, a ligand-based virtual screening (LBVS) approach was employed using a 2D/3D pharmacophore model derived from BED to perform in silico screening of an Enamine compound library, which encompasses a broad and diverse chemical space. A key objective was to compare the predictive performance of this pharmacophore-based workflow with a structure-based (SB) strategy incorporating molecular docking and molecular dynamics (MD) simulations. Notably, the top-ranked LBVS hits were consistently validated by docking and MD analyses, showing stable binding and interaction patterns comparable or superior to those of BED. This convergence between ligand-based (LB) and SB methods highlights the internal coherence of the workflow and supports the robustness of the pharmacophore hypothesis. The identified scaffolds generally displayed high hydrophobicity, consistent with the physicochemical nature of the binding site, but resulting in limited aqueous solubility and complicating their experimental evaluation. While these features confirm the importance of hydrophobic interactions in MexY recognition, with a particular focus on some few residues, such as Phe560, it also underscores the need for formulation strategies or rational scaffold modifications introducing moderate polarity without weakening key contacts. Overall, the integrated computational strategy not only yields promising lead chemical structures but also provides a solid basis for their future optimization, ultimately supporting the design of new efflux pump inhibitors (EPIs) capable of contributing to improved antibiotic susceptibility in multidrug-resistant PA strains. Full article

Komagataeibacter strains are important bacterial cellulose producers, yet closely related isolates can differ in cellulose yield, pellicle properties, and genetic stability during propagation. Such variability suggests that lineage structure and mobile genetic elements both contribute to strain-level genomic divergence. Here, complete genome comparisons were used to integrate vertical relatedness, gene-content structure, cellulose-associated signatures, and mobilome heterogeneity across 22 closed Komagataeibacter assemblies. A maximum likelihood phylogeny inferred from 642 single copy core genes provided the lineage scaffold. An anvi’o pangenome analysis defined a constant core gene cluster component across genomes and a noncore fraction that accounted for most of the genome differences in gene content. Targeted features linked to cellulose biosynthesis and local c-di-GMP-associated context were extracted from each genome. These features captured differences in bcs neighborhood composition and the presence of nearby GGDEF and EAL domain signals. The resulting feature matrix was projected by principal component analysis to summarize between-genome variation. Mobilome profiles were strongly strain dependent. Plasmid homology clustering identified 12 clusters comprising 36 plasmids from 13 genomes, including two dominant clusters of seven and six plasmids. Mash-based distance summaries further distinguished clusters consistent with conserved backbones from clusters consistent with heterogeneous, module-driven relationships. Prophage sequences, assessed as VIBRANT-predicted regions, were widespread but sparse per genome and dominated by medium length fragments. Insertion sequence burden ranged from 50 to 181 elements per genome, indicating substantial differences in transposition-associated sequence content. Pairwise association tests did not support robust cross module covariation beyond expected relationships among pangenome composition metrics at the current sampling depth. Overall, these results provide a complete genome reference framework linking lineage structure and mobilome heterogeneity, and they define reusable resources for comparative studies in bacterial cellulose biotechnology. Full article

Listeria innocua is a bacterium frequently detected in food and food production plants (FPPs). Understanding the heterogeneity of L. innocua food isolates is essential for predicting potential food safety threats and developing preventive and control measures. This study aimed to characterize L. innocua isolated from raw drinking milk by investigating the genomic features related to virulence, antimicrobial resistance, and persistence using whole-genome sequencing (WGS), along with phenotypic antimicrobial susceptibility testing using the disk diffusion method. All ten isolates analyzed in this study belonged to sequence type (ST) 492 and were distantly related to the reference strain. A total of 80 virulence-associated genes were identified, including the complete Listeria Pathogenicity Islands-3 (LIPI-3) and LIPI-4 clusters typically found in virulent L. monocytogenes clones, as well as 66 additional genes involved in adhesion, invasion, motility, post-translational modification, regulation, immune modulation, and stress survival. Stress survival islet 2 (SSI-2) and genes encoding the Clp protease complex (clpC, clpE, clpP), which support both persistence and virulence, were also detected, whereas LIPI-1 and internalin genes were not detected. The antimicrobial resistance determinants included fosX, lin, norB, sul, and three multidrug efflux pumps (lde, mdrL and mdrM). Mobile genetic elements (plasmids, prophages, or transposons) were not detected. All isolates were phenotypically susceptible to benzylpenicillin, ampicillin, meropenem, erythromycin, and trimethoprim–sulfamethoxazole. These findings underscore the importance of ongoing genomic surveillance of L. innocua in food environments and highlight the need to assess the potential risk posed by specific lineages, such as ST492, to food safety. Full article

Xeroderma pigmentosum group B (XPB/ERCC3) and group D (XPD/ERCC2) helicases are integral components of the transcription factor IIH (TFIIH) complex, coordinating DNA unwinding during transcription initiation and nucleotide excision repair (NER). XPB functions as an ATP-driven translocase that generates torsional strain to promote promoter melting and DNA opening at lesion sites, whereas XPD acts as a 5′ to 3′ helicase responsible for lesion verification and extension of the repair bubble. Structural and biochemical studies have clarified how TFIIH subunits regulate these helicases—p52 and p8 modulate XPB’s translocation activity, while p44, p62, and MAT1 control XPD’s helicase function through conformational and compositional transitions within the complex. Beyond their canonical roles, XPB and XPD participate in diverse cellular pathways, including cell-cycle regulation and oxidative stress response, highlighting their involvement in maintaining genome integrity beyond repair and transcription. Mutations in either helicase lead to xeroderma pigmentosum (XP), trichothiodystrophy (TTD), or combined XP/Cockayne syndrome (XP/CS) phenotypes, emphasizing the essential role of TFIIH integrity for human health. Recent biochemical and pharmacological advances have further revealed the therapeutic relevance of these helicases—XPB as a target of small-molecule inhibitors such as triptolide, Minnelide, and spironolactone, and XPD as a potential modulator of cancer sensitivity to DNA-damaging treatments. Collectively, XPB and XPD exemplify the structural and functional versatility of TFIIH helicases across repair, transcription, and genome maintenance. Full article

The naviculoid genus Luticola exhibits a high degree of morphological convergence, complicating species delimitation when based solely on traditional morphometrics. Here, we describe Luticola edaphica sp. nov., a new species isolated from the forest soils of Mount Sestra (Primorsky Territory, Russian Far East) using an integrative taxonomic approach (phylogenetic, morphological, ultrastructural, and life cycle data). Molecular phylogenetic analysis, based on the chloroplast rbcL gene, placed the new strain within the Luticola clade, showing the closest affinity to L. tenera. However, L. edaphica is distinguished from similar Luticola species by a unique combination of morphological traits (structure of the valvocopula, maximal valve length and width, position and number of striae in 10 µm, central area, and distal raphe ends). A comprehensive study of its life cycle revealed that L. edaphica is homothallic and capable of both cis- and trans-anisogamy, with the latter being reported for the genus for the first time. Full article

Environmental toxins can impair gut microbiota and increase intestinal permeability, contributing to various health problems. While many such toxins are known to disrupt tight junctions and compromise barrier function, research specifically examining carbon tetrachloride (CCl₄) as a trigger of intestinal epithelial barrier dysfunction remains limited. In this study, 54 young Western albino male rats, weighing 180–200 g, were randomly assigned to nine experimental groups, each comprising six rats. Group 1 received 1 mL of oral saline and served as a control. Groups 2 and 3 received 0.2 g/kg body weight probiotic and prebiotic, respectively, for four weeks. CCl₄ (1 mL/kg, i.p.) was administered either at the beginning of day 1 (damage induction; Group 4) or at the end of day 28 (protection assessment; Group 7). Intervention groups received probiotics and prebiotics for 4 weeks after (therapeutic) CCl₄ exposure on day 1 in Groups 5 and 6, respectively. Groups 8 and 9 received probiotics and prebiotics for 4 weeks before CCl₄ exposure on day 28, respectively. Quantification of gut bacterial populations, serum levels of Occludin and Zonulin, as biomarkers of intestinal permeability, and histopathological analysis of intestinal tissue were conducted. CCl₄ induces significant intestinal epithelial barrier dysfunction with marked histopathological alterations. Probiotic treatment was more effective than prebiotics at normalizing serum Zonulin and Occludin levels in CCl₄-induced intestinal damage. Probiotics restore microbial balance by suppressing the overgrowth of pathogenic organisms, while prebiotics confer partial protection. CCl₄-induced gut barrier disruption is restored through probiotic supplements by restoring gut microbial balance and normalizing tight junction-associated biomarkers. Full article