Search Results (60)

The precursor-derived ceramic route is recognized as an advanced and efficient technique for fabricating ceramic matrix composites, particularly suitable for the development and microstructural tailoring of continuous fiber-reinforced ceramic matrix composites. In this work, octamethylcyclotetrasiloxane and tetravinylcyclotetrasiloxane were employed as monomers to synthesize a branched siloxane via ring-opening polymerization. A subsequent hydrosilylation reaction led to the formation of polyvinylsiloxane with a three-dimensional crosslinked structure. The precursor exhibited excellent fluidity, adjustable viscosity, and superior thermosetting characteristics, enabling efficient impregnation and densification of reinforcements through the polymer infiltration and pyrolysis process. Upon pyrolysis, the polyvinylsiloxane gradually converted from an organic polymer to an amorphous inorganic ceramic phase, yielding silicon oxycarbide ceramics with a high ceramic yield of 81.3%. Elemental analysis indicated that the resulting ceramic mainly comprised silicon and oxygen, with a low carbon content. Furthermore, the material demonstrated a stable dielectric constant (~2.5) and low dielectric loss (<0.01), which are beneficial for enhanced thermal stability and dielectric performance. These findings offer a promising precursor system and process reference for the low-cost production of high-performance, multifunctional ceramic matrix composites with strong potential for engineering applications. Full article

The seepage diffusion of cement grouting materials into a sandy medium is influenced by the skeleton’s adsorption and the pore channels’ tortuosity, resulting in heterogeneous retention of cement particles during migration. This study established a theoretical model for the filtration coefficient based on the mass balance equation and linear filtration law. Grouting tests were conducted to determine the density of the cement slurry at various diffusion positions, and the filtration coefficient was calculated using the theoretical model. Results indicate that the filtration coefficient varies dynamically along the diffusion distance rather than remaining constant. The surface filtration range of Grade 42.5 Portland Cement slurry in sample S1 is approximately 30 cm, with a final diffusion distance of 190 cm. In contrast, the surface filtration ranges for the 800 mesh superfine cement in S2 and the 1250 mesh superfine cement in S3 are less than 10 cm, resulting in final diffusion distances of 69 cm and 87 cm, respectively. This demonstrates that a longer surface filtration range in the sand sample corresponds to a farther final diffusion distance of the slurry. Additionally, a larger ratio of sand pore diameter to cement particle size results in a smaller filtration coefficient and a greater slurry diffusion distance. Under a constant water–cement ratio, smaller cement particle sizes are associated with decreased slurry fluidity, which reduces the diffusion of cement slurry within the sandy medium. The research findings provide valuable insights for designing borehole spacing in grouting treatment for sandy media. Full article

SiC-W₂B₅/C composites were prepared through a novel and simple processing route (reaction hot-pressing). The density of composites increased from 96.1% to 99.2% with the increase in SiC content from 5 to 30 vol%, leading to significant improvements in mechanical properties such as flexural strength, fracture toughness, and Vickers hardness, which for the highest W15S30 composite were measured at 292.3 MPa, 6.12 MPa·m^1/2, and 3.32 GPa, respectively. The fracture morphology exhibited a mixed fracture mode of transgranular and intergranular, along with a pull-out phenomenon, indicating a well-combined interface. The sintering process involved Si powder acting as a liquid-phase sintering agent, reacting with B₄C to increase the B concentration and promote the generation of W₂B₅, as well as reacting with the carbon phase to generate a transition phase of Si-B-C. The presence of this transition phase enhanced the interface bonding strength and catalyzed the graphitization process. As the SiC content increased, the promotion effect became more pronounced, with the degree of graphitization increasing from 59.2% to 66.2%. Full article

In this paper, polymethylhydrosiloxane (PMHS) and ethanol were used as raw materials to synthesize the ceramic precursor of side ethoxy polysiloxane (PESO) using dehydration and a dealcoholization reaction, which had a ceramic yield of 87.15% and a very low residual carbon content. With the quartz fiber as a reinforcer, the silica matrix composites (SiO_2f/SiO₂) with a double-layer interface (PyC-SiO₂/BNNSs) coating were manufactured using precursor impregnation pyrolysis (PIP). The as-prepared SiO_2f/SiO₂ possessed an excellent mechanical property, which exhibited obvious fiber pull-out and debonding phenomena from a fracture morphology. The flexural strength and fracture toughness of SiO_2f/SiO₂ reached 63.3 MPa and 2.52 MPa·m^1/2, respectively. Moreover, the SiO_2f/SiO₂ had suitable dielectric properties, with a dielectric constant of about 2.5 and a dielectric loss of less than 0.01. This work provides an important concept for the enhancement of the dielectric properties and mechanical properties of quartz fiber-reinforced ceramic matrix composites, as well as in the preparation of wave-transmissivity composites. Full article

One new gliotoxin derivative fumianthrogliotoxin (1), one new indoquizoline alkaloid N3-(methyl propionate) indoquizoline (2), and three novel indole alkaloids, anthroxyindole (3), (±)-asperfumiindole A (4), and (±)-asperfumiindole B (5), together with 16 known compounds (6–21), were isolated from the culture of deep-sea derived fungus Aspergillus fumigatus AF1. Their chemical structures and absolute configurations were determined through the analysis of NMR data in combination with electronic circular dichroism (ECD) calculations and other spectroscopic analyses. Compounds 2–11 and 13–21 were evaluated for anti-pulmonary fibrosis activity. Compounds 8 and 13 displayed significant downregulation of the mRNA expression levels of all three molecular markers (COL1A1, α-SMA and FN1), with compound 13 exhibiting the best performance among all the tested compounds. Full article

Porcine circovirus type 2 (PCV2) is an important swine pathogen that has caused considerable economic losses in the global swine industry. During our surveillance of pigs in Shandong, China, from 2018 to 2020, we found that the PCV2 infection rate was 7.89% (86/1090). In addition, we found frequent mixed infections of PCV2 with porcine reproductive and respiratory syndrome virus (PRRSV), classical swine fever virus (CSFV), and porcine herpesvirus (PRV). Thirteen positive clinical samples were selected to amplify the complete genome of PCV2, and were sequenced. Among the 13, we detected two genotypes: PCV2b (1/13) and PCV2d (12/13). This suggests that PCV2d is the dominant genotype circulating in Shandong Province. Additionally, we found three positively selected sites in the ORF2 region, located on the previously reported antigenic epitopes. This investigation will contribute to understanding of the molecular epidemiology and genetic diversity of PCV2 strains in China. Full article

Superfine cement is widely used in building reinforcement and repair, special concrete manufacturing, and environmental protection engineering due to its high toughness, high durability, good bonding strength, and environmental friendliness. However, there are some problems in superfine cement slurry, such as high bleeding rate, prolonged setting time, and consolidated body volume retraction. In this article, on the premise of using the excellent injectability of superfine cement slurry, the fluidity, setting time, reinforcement strength, and volume expansion rate of novel expansive superfine cement slurries with varying proportions were analyzed by adding expansion agent UEA, naphthalene-based water reducer FDN-C, and triisopropanolamine accelerating agent TIPA. The results show that under most mix ratios, the bleeding rate and fluidity of the novel superfine cement slurry initially increase and decrease with rising water-reducing agent dosage. The initial setting time generally decreases with accelerating agent dosage, reaching a minimum value of 506 min, representing a 33.68% reduction compared to the benchmark group (traditional superfine cement). Under normal conditions, the compressive strength of the net slurry consolidation body is positively correlated with expansion agent dosage, achieving maximum strengths of 8.11 MPa at three days and 6.93 MPa at 28 days; these values are respectively higher by 6.7 MPa and 2.6 MPa compared to those in the benchmark group. On the seventh day, the volume expansion rate of the traditional superfine cement solidified sand body ranges from −0.19% to −0.1%, while that for the corresponding body formed from the novel superfine cement is between 0.41% and 1.33%, representing a difference of 0.6–1.43%. After the on-site treatment of water and sand-gushing strata, the core monitor rate of the inspection hole exceeds 70%. The permeability coefficient of the stratum decreases to a range between 1.47 × 10⁻⁶ and 8.14 × 10⁻⁶ cm/s, resulting in nearly a thousandfold increase in stratum impermeability compared to its original state. Hence, the findings of this research hold practical importance for the future application of such materials in the development of stratum reinforcement or building repair. Full article

This study aimed to determine the optimal dietary net energy concentration for the reproductive performance, immune function, milk composition, and gut microbiota of primiparous sows during lactation. Forty primiparous lactating sows (Landrace × Yorkshire) with similar body backfat thicknesses were randomly allocated into five treatment groups and fed diets with different dietary net energy concentrations of 10.05 MJ/kg, 10.47 MJ/kg, 10.89 MJ/kg, 11.30 MJ/kg, and 11.72 MJ/kg. The results showed that there were no differences in the performance of piglets, while there was a decrease in the daily feed intake of sows (p = 0.079, linear) as dietary net energy concentration increased. With the increasing dietary net energy concentration, the plasma insulin levels of sows increased (p < 0.01, linear), the plasma glucose levels tended to increase (p = 0.074, linear), and the blood urea nitrogen levels tended to decrease (p = 0.063, linear). Moreover, the plasma total superoxide dismutase activity of sows increased (p < 0.05, quadratic) and the plasma malondialdehyde content of sows decreased (p < 0.05, quadratic) by increasing the dietary net energy concentration. Interestingly, with the increase in dietary net energy concentration, the plasma immunoglobulin M content of sows increased, the milk immunoglobulin M, immunoglobulin G, immunoglobulin A and the percentage of milk fat increased (p < 0.05, linear), and the milk secretory immunoglobulin A content also increased (p < 0.05, linear and quadratic). The milk immunoglobulins and milk fat content of sows fed with net energy concentration of 11.72 MJ/kg were highest. Moreover, there were significant differences in the α-diversity, β-diversity, and relative abundance of gut microbiota in sows fed with different dietary net energy concentrations. At the phylum level, Spirochaetota and Bacteroidota in the gut microbiota of sows were mainly affected by increasing the dietary net energy concentration. Furthermore, the correlation analysis showed that milk immunoglobulin content had a significant negative correlation with the relative abundance of Bacteroidota, and plasma malondialdehyde content also had a significant negative correlation with the relative abundance of Spirochaetota. In summary, these results suggest that increasing the dietary net energy concentration to 11.72 MJ/kg can increase immunological substances in milk, improve milk quality, and alter the composition of gut microbiota in primiparous lactating sows. Full article

Adipose tissue is composed of adipocytes, stromal vascular fraction, nerves, surrounding immune cells, and the extracellular matrix. Under various physiological or pathological conditions, adipose tissue shifts cellular composition, lipid storage, and organelle dynamics to respond to the stress; this remodeling is called “adipose tissue plasticity”. Adipose tissue plasticity includes changes in the size, species, number, lipid storage capacity, and differentiation function of adipocytes, as well as alterations in the distribution and cellular composition of adipose tissue. This plasticity has a major role in growth, obesity, organismal protection, and internal environmental homeostasis. Moreover, certain thresholds exist for this plasticity with significant individualized differences. Here, we comprehensively elaborate on the specific connotation of adipose tissue plasticity and the relationship between this plasticity and the development of many diseases. Meanwhile, we summarize possible strategies for treating obesity in response to adipose tissue plasticity, intending to provide new insights into the dynamic changes in adipose tissue and contribute new ideas to relevant clinical problems. Full article

Lonicerae japonicae Flos (LJF) is a natural plant containing abundant antioxidant ingredients. In order to extract more antioxidants from LJF, in this study, a novel strategy was proposed for optimizing the extraction factor level by response surface methodology with a tailored deep eutectic solvent (DES) as the extraction solvent and antioxidant ability as the evaluation index. After optimizing the composition of DES and the extraction condition, the extracts obtained by our proposed method yielded better antioxidant ability (229.1–249.1 μmol TE/g DW) and higher antioxidant contents (34.2–36.5 mg GAE/g DW for total phenolics and 119.6–123.0 mg RE/g DW for total flavonoids) from LJF in 5 min without organic solvent consumption that were significantly superior to the Chinese Pharmacopoeia extraction method. The K-T solvation parameter and a scanning electron microscope were adopted to explore the extraction mechanism, and the results showed that the polarity and damage effect on plant cells of DES were crucial for the extraction of antioxidants. In addition, after combining the HPLC fingerprint and partial least squares model, chlorogenic acid, rutin, and 3,5-O-Dicaffeoylquinic acid were screened as the antioxidant Q-markers of LJF. This work demonstrates that an optimization strategy based on antioxidant ability and tailored DES has the potential to extract more antioxidants from natural plants. Full article

Soluble starch synthases (SSs) play important roles in the synthesis of cassava starch. However, the expression characteristics of the cassava SSs genes have not been elucidated. In this study, the MeSSIII-1 gene and its promoter, from SC8 cassava cultivars, were respectively isolated by PCR amplification. MeSSIII-1 protein was localized to the chloroplasts. qRT-PCR analysis revealed that the MeSSIII-1 gene was expressed in almost all tissues tested, and the expression in mature leaves was 18.9 times more than that in tuber roots. MeSSIII-1 expression was induced by methyljasmonate (MeJA), abscisic acid (ABA), and ethylene (ET) hormones in cassava. MeSSIII-1 expression patterns were further confirmed in proMeSSIII-1 transgenic cassava. The promoter deletion analysis showed that the −264 bp to −1 bp MeSSIII-1 promoter has basal activity. The range from −1228 bp to −987 bp and −488 bp to −264 bp significantly enhance promoter activity. The regions from −987 bp to −747 bp and −747 bp to −488 bp have repressive activity. These findings will provide an important reference for research on the potential function and transcriptional regulation mechanisms of the MeSSIII-1 gene and for further in-depth exploration of the regulatory network of its internal functional elements. Full article

Vernonia patula Merr. (VP) is a traditional medicine used by the Zhuang and Yao people, known for its therapeutic properties in treating anemopyretic cold and other diseases. Distinguishing VP from similar varieties such as Praxelis clematidea (PC), Ageratum conyzoides L. (AC) and Ageratum houstonianum Mill (AH) was challenging due to their similar traits and plant morphology. The HPLC fingerprints of 40 batches of VP and three similar varieties were established. SPSS 20.0 and SIMCA-P 13.0 were used to statistically analyze the chromatographic peak areas of 37 components. The results showed that the similarity of the HPLC fingerprints for each of the four varieties was >0.9, while the similarity between the control chromatogram of VP and its similar varieties was <0.678. Cluster analysis and partial least squares discriminant analysis provided consistent results, indicating that all four varieties could be individually clustered together. Through further analysis, we found isochlorogenic acid A and isochlorogenic acid C were present only in the original VP, while preconene II was present in the three similar varieties of VP. These three components are expected to be identification points for accurately distinguishing VP from PC, AC and AH. Full article

Chemokines are cytokines with chemoattractant capacities that exert their physiological functions through the binding of chemokine receptors. Thus, chemokine and receptor complexes exert important roles in regulating development and homeostasis during routine immune surveillance and inflammation. Compared to mammals, the physiology and structure of chemokine receptors in fish have not been systematically studied. Furthermore, the salmonid-specific whole genome duplication has significantly increased the number of functional paralogs of chemokine receptors. In this context, in the current study, trout exhibited 17 cxcr genes, including 12 newly identified and 5 previously identified receptors. Interestingly, gene expression of brain cxcr1 and cxcr4, kidney cxcr3 and cxcr4, and spleen cxcr3, cxcr4, and cxcr5 subtypes were altered by bacterial infection, whereas brain cxcr1, kidney cxcr1 and cxcr7, and liver cxcr2, cxcr3, and cxcr4 subtypes were changed in response to environmental changes. Based on protein structures predicted by ColabFold, the conserved amino acids in binding pockets between trout CXCR4.1 subtypes and human CXCR4 were also analyzed. Our study is valuable from a comparative point of view, providing new insights into the identification and physiology of salmonid chemokine receptors. Full article

Formaldehyde is a colorless, pungent, and highly volatile toxic gas known for its detrimental effects on the brain, respiratory, and nervous systems. The adsorption method emerges as an effective approach for detecting and mitigating formaldehyde gas, with the adsorption material serving as its core component. Graphene, a two-dimensional nanomaterial with remarkable properties, exhibits enhanced adsorption capabilities when subjected to metal doping, which alters its local geometric and charge characteristics. In this investigation, theoretical first-principles density functional technology was employed to optimize the efficiency of Fe-doped graphene in formaldehyde adsorption. The calculated adsorption bond length and energy were used to determine the type of adsorption. Then, the calculated Bader charge, density of states (partial density of states), and differential valence charge density distribution were used to analyze the electron transfer process before and after adsorption. Finally, the theoretical optical properties analysis result was applied to analyze the potential of Fe-doped graphene for formaldehyde detection. The findings indicated that Fe-doped graphene constitutes a viable and stable doping structure, accompanied by a notable shift in valence charge distribution around the doped iron atom. This altered charge distribution facilitated the chemical adsorption process, leading to reduced adsorption spacing and increased adsorption energy. Throughout the chemical adsorption process, there was evident charge transfer between carbon (formaldehyde) and iron atoms, as well as between oxygen (formaldehyde) and iron atoms. The formation of adsorption bonds primarily involved the p-orbital electrons of carbon and oxygen atoms, along with the p- and d-orbital electrons of iron atoms. Ultimately, the Fe-doped graphene material exhibited promising applications in the realm of formaldehyde molecular detection, marked by significant theoretical disparities in optical properties before and after the adsorption process. Full article

Eight new scalarane sesterterpenes, phyllofenones F–M (1–8), together with two known analogues, carteriofenones B and A (9–10), were isolated from the marine sponge Phyllospongia foliascens collected from the South China Sea. The structures of these compounds were determined based on extensive spectroscopic and quantum chemical calculation analysis. The antibacterial and cytotoxic activity of these compounds was evaluated. Among them, only compounds 4 and 6 displayed weak inhibitory activity against Staphylococcus aureus and Escherichia coli, with MIC values of 16 μg/mL and 8 μg/mL, respectively. Compounds 1–10 exhibited cytotoxic activity against the HeLa, HCT-116, H460, and SW1990 cancer cell lines, with IC₅₀ values ranging from 3.4 to 19.8 μM. Full article