Search Results (3,864)

Ion channels are protein pores that regulate ionic flow across cell membranes, enabling vital processes such as nerve signaling. They often conduct multiple ionic species simultaneously, leading to complex nonlinear transport phenomena. Because experimental techniques provide only indirect measurements of ion channel currents, mathematical models—particularly Poisson–Nernst–Planck (PNP) equations—are indispensable for analyzing the underlying transport mechanisms. In this work, we examine ionic transport through a one-dimensional steady-state PNP model of a narrow membrane channel containing multiple cation species of different valences. The model incorporates a small fixed charge distribution along the channel and imposes relaxed electroneutrality boundary conditions, allowing for a slight charge imbalance in the baths. Using singular perturbation analysis, we first derive approximate solutions that capture the boundary-layer structure at the channel—reservoir interfaces. We then perform a regular perturbation expansion around the neutral reference state (zero fixed charge with electroneutral boundary conditions) to obtain explicit formulas for the steady-state ion fluxes in terms of the system parameters. Through this analytical approach, we identify several critical applied potential values—denoted $V_k^a$ (for each cation species k), $V^b$, and $V^c$—that delineate distinct transport regimes. These critical potentials govern the sign of the fixed charge’s influence on each ion’s flux: depending on whether the applied voltage lies below or above these thresholds, a small positive permanent charge will either enhance or reduce the flux of each ion species. Our findings thus characterize how a nominal fixed charge can nonlinearly modulate multi-ion currents. This insight deepens the theoretical understanding of nonlinear ion transport in channels and may inform the interpretation of current–voltage relations, rectification effects, and selective ionic conduction in multi-ion channel experiments. Full article

Understanding the feeding mechanisms and interspecific coexistence of sharks is crucial for effective conservation. This study conducted stable isotope analysis on muscle and liver samples from 449 individuals of eight common bycatch shark species collected via bottom trawling in the northern South China Sea (NSCS). Results revealed significant differences in δ¹³C and δ¹⁵N values among species and tissue types. Scoliodon laticaudus exhibited the highest trophic position (TP_muscle = 4.60 ± 0.33; TP_liver = 4.53 ± 0.29), while Apristurus platyrhynchus had the lowest (TP_muscle = 2.97 ± 0.44; TP_liver = 2.75 ± 0.53). Muscle and liver isotopic signals were consistent, but δ¹³C differences indicated distinct carbon sources, with Carcharhinus sorrah linked to deep-sea organic matter and S. laticaudus to coastal inputs. Significant correlations between δ¹³C/δ¹⁵N and body length in A. platyrhynchus and Cephaloscyllium fasciatum suggest ontogenetic shifts in diet and habitat toward deeper waters. Trophic niche analysis using corrected standard ellipse area (SEAc) showed Halaelurus burgeri with the widest trophic niche (SEAc > 1.7‰²), reflecting a broad diet, while C. fasciatum had the narrowest (SEAc < 0.3‰²), indicating specialized feeding. Additionally, H. burgeri and C. sarawakensis exhibited significant niche differentiation, reducing interspecific competition, whereas C. fasciatum and Squalus megalops showed high niche overlap, suggesting intense resource competition. The narrower liver niche of C. sarawakensis may reflect recent habitat constriction due to bottom trawling. This study elucidates the feeding ecology and habitat resource utilization of NSCS sharks, providing a scientific basis for effective conservation strategies for shark populations in the region. Full article

This study represents the first evaluation of the effects of zinc–carbon dot nano-fertilizers (Nano-ZCDs) on the growth of Bok choy (Brassica chinensis L.) and soil health under multi-batch consecutive foliar spraying during three successive cultivation cycles. The results showed that relative to CK, Nano-ZCDs significantly elevated the fresh weight of Bok choy cultivation across three consecutive harvests, by 75.5 ± 1.8%, 75.1 ± 0.2%, and 74.6 ± 0.4%, respectively. Meanwhile, the nutritional value, including amino acids, vitamin C, soluble sugars, proteins, and Zn accumulation, was markedly enhanced by Nano-ZCDs. Additionally, Nano-ZCDs significantly improved soil water content, Eh, soil organic carbon, available potassium, and available phosphorus in the rhizosphere soil. It also enhanced the complexity, stability, and species richness of the bacterial community. Based on the Cornell Soil Health Assessment system, the soil health index of the Nano-ZCDs group was significantly 8.1% higher than that of the CK group. Therefore, multi-batch consecutive applying of Nano-ZCDs promoted Bok choy cultivation growth and improved its quality, without impairing soil health. This study suggests that Nano-ZCDs can be applied in agricultural production processes to promote the sustainable development of agricultural systems. Full article

Cover crop mixes play an important role in enhancing soil health, nutrient turnover, and ecosystem resilience; yet, maintaining even seed dispersion and planting uniformity is difficult due to significant variances in seed physical and aerodynamic properties. These discrepancies produce non-uniform seeding and species separation in drill hoppers, which has an impact on stand establishment and biomass stability. The thousand-grain weight is an important measure for determining cover crop seed quality and yield since it represents the weight of 1000 seeds in grams. Accurate seed counting is thus a key factor in calculating thousand-grain weight. Accurate mixed-seed identification is also helpful in breeding, phenotypic assessment, and the detection of moldy or damaged grains. However, in real-world conditions, the overlap and thickness of adhesion of mixed seeds make precise counting difficult, necessitating current research into powerful seed detection. This study addresses these issues by integrating deep learning-based computer vision algorithms for multi-seed detection and counting in cover crop mixes. The Canon LP-E6N R6 5D Mark IV camera was used to capture high-resolution photos of flax, hairy vetch, red clover, radish, and rye seeds. The dataset was annotated, augmented, and preprocessed on RoboFlow, split into train, validation, and test splits. Two top models, YOLOv5 and YOLOv7, were tested for multi-seed detection accuracy. The results showed that YOLOv7 outperformed YOLOv5 with 98.5% accuracy, 98.7% recall, and a mean Average Precision (mAP 0–95) of 76.0%. The results show that deep learning-based models can accurately recognize and count mixed seeds using automated methods, which has practical applications in seed drill calibration, thousand-grain weight estimation, and fair cover crop establishment. Full article

Detecting forest tree species distribution using satellite imagery with deep-learning models is essential for effective forest management. While sufficient training samples are crucial for developing deep-learning-based tree species classification models, creating these training samples requires significant resources. Therefore, understanding the optimal balance between model accuracy and training sample size is essential for efficient resource allocation. Here, we determined the optimal training sample size for forest tree species classification using Sentinel-2 imagery and the U-Net model. The study area comprised the Seoul–Gyeonggi region of South Korea, where the nine dominant tree species were selected for classification. We utilized multi-temporal Sentinel-2 imagery, incorporating spectral, vegetation, and textural features. Optimal points were identified using Locally Estimated Scatterplot Smoothing (LOESS) regression. The maximum overall accuracy reached 61%, with 90% and 95% of the maximum accuracy with training sample sizes of 2.37%–2.67% and 4.42%–5.89%, respectively. The congeneric Pinus and Quercus groups had major confusion, with species-specific F1-scores ranging from 0.40 (Robinia pseudoacacia) to 0.75 (Pinus koraiensis). These results provide practical guidelines for efficient resource allocation in tree species classification. Rather than pursuing excessive data collection beyond the optimal point, integrating multiple sensor types can overcome existing limitations and enhance classification accuracy. Full article

Gleichenella pectinata, known as ‘Star fern’, is a species traditionally used by Amazonian indigenous communities to treat various diseases. The objective of this study was to evaluate the bioactive compounds and antioxidant, antimicrobial, antitumor, and anti-inflammatory activities of G. pectinata leaves. The study included the determination of physicochemical parameters (pH, soluble solids, titratable acidity, moisture, and ash), phytochemical screening, mineral analysis by atomic absorption and quantification of bioactive compounds (vitamin C, organic acids, carotenoids, chlorophylls, and phenols) by liquid chromatography (RRLC). Antioxidant (ABTS and DPPH), antimicrobial (ATCC bacteria and fungi, and multi-resistant strains), antitumor and anti-inflammatory activities were evaluated. The results showed the presence of acetogenins, high concentrations of malic acid (56,559.7 mg/100 g DW), β-carotene (266.6 mg/100 g DW), chlorophyll b (684.7 mg/100 g DW), ferulic acid (3163.5 mg/100 g DW) and quercetin glucoside (945.9 mg/100 g DW). The freeze-dried ethanolic extracts showed greater efficacy against Pseudomonas aeruginosa ATCC (12.0 mg/mL) and multidrug-resistant strains of E. coli (6.6 mg/mL) and P. aeruginosa (6.6 mg/mL). In addition, the extract exhibited moderate antiproliferative activity (IC₅₀: 0.98–1.98 mg/mL) in hepatocellular and cervical carcinoma cell lines. In conclusion, this study provides the first evidence of the antitumor and bioactive potential of G. pectinata, supporting its value as a natural source of functional compounds with potential pharmacological applications. Full article

Climate-change-induced thermal stress poses a significant threat to cold-adapted aquatic species, particularly fish endemic to high-altitude ecosystems such as Gymnocypris eckloni, which is native to the Qinghai-Tibetan Plateau. To elucidate the molecular and metabolic mechanisms underlying their response to elevated temperatures, we integrated RNA-seq, miRNA-seq, and LC-MS-based metabolomic analyses of liver tissue from fish exposed to chronic thermal stress (HT) versus control (CT) conditions. Although no significant differences were observed in growth parameters, histopathological examination revealed structural damage under heat stress. Transcriptomic analysis identified widespread dysregulation of genes involved in energy metabolism, with significant downregulation of pathways related to amino acid, fatty acid, glucose, and oxidative phosphorylation. In contrast, upregulated DEGs were enriched in N-glycan biosynthesis, protein processing in the endoplasmic reticulum, and phagosome. Concomitant miRNA profiling revealed differentially expressed miRNAs, including miR-196a-5p, miR-132-3p, and miR-181b-5p, which were predicted to regulate key metabolic genes such as ugt1a1, pepck, and calr. Metabolomic analysis further demonstrated significant alterations in metabolic profiles, with glutathione metabolism, tryptophan metabolism, steroid hormone biosynthesis, and pyruvate metabolism emerging as central pathways in the heat stress response. Integrated multi-omics analysis confirmed coordinated regulation of these pathways, highlighting the critical role of glutathione and tryptophan, as well as disruptions in purine and energy metabolism. The DEMiR-DEG-DEM networks involving miR-196a-5p-pepck-PEP, miR-133a-3p-gne-UDP-GlcNAc, and miR-132-3p-ugt1a1-Bilirubin may play an important role in thermal stress. This study provided a new perspective on the molecular, regulatory, and metabolic adaptations of Gymnocypris eckloni to thermal stress, identifying potential biomarkers and regulatory networks that may inform conservation strategies for cold-water fish under global warming. Full article

Coal mine gas with methane concentrations below 8% cannot sustain stable self-combustion, posing significant challenges for safe utilization and greenhouse gas mitigation. To address this limitation, we developed a large-scale industrial square rotary regenerative thermal oxidizer (RTO) capable of high-efficiency oxidation under ultra-low methane conditions. This work integrates multi-scale computational fluid dynamics (CFD) modeling, laboratory and pilot-scale physical experiments, and multi-physics coupled simulations to capture the complex interactions of fluid flow, species transport, and thermal response in regenerative ceramics. Compared with conventional circular or three-bed RTOs, the proposed square rotating design achieves 13% higher heat storage utilization, 15% smaller floor area, and enhanced spatial uniformity of the temperature field. Multi-scale simulations reveal that increasing methane molar fraction (CH₄) from 0.012 to 0.017 raises the peak temperature from 1280 K to 1350 K, reduces the burnout height from 1.18 m to 1.15 m, and, under constant oxygen supply, extends the high-temperature zone to 1450 K with a stabilized burnout position at 1.06 ± 0.01 m. Incorporating a 15° conical expansion combustion chamber increases local turbulent kinetic energy by 17.4%, accelerating oxidation while maintaining methane removal rates > 98% within an optimized bottom blowing time of 30–90 s. This study not only provides validated design thresholds for ultra-low concentration methane oxidation—such as temperature windows, buffer zones, and switching cycles—but also offers an engineering framework for scaling RTO systems to industrial coal mine applications. This advances both energy recovery efficiency and methane emission control, demonstrating clear advantages over existing RTO configurations. Full article

Conventional agriculture, focusing on productivity rather than sustainability, have long abandoned hulled wheats. With them not only striking genetic diversity but valuable, health-promoting food sources became lost. Although einkorn and emmer—two of the most ancient wheat species—are generally considered good candidates of sustainable agriculture especially for pesticide-free cropping, they have remained largely unrecognized. To assess their agronomic potential in comparison with modern wheats grown under the same conditions, comprehensive research was conducted, combining multi-location participatory on-farm and small-plot trials. Our findings confirmed that most landraces of emmer and einkorn exhibited strong weed suppression ability, making them suitable for organic cultivation, and effective resistance against diseases—including Fusarium spp. and associated deoxynivalenol (DON) mycotoxin accumulation. Both species were entirely avoided by cereal leaf beetles (Oulema spp.) and had, on average, 2.6% more grain protein content than common wheat. Although they command significantly higher market prices, their (hulled) yields were comparable to modern wheat only in extreme years or at sites typically producing 3–5 t/ha of wheat. Nevertheless, the cultivation of emmer and einkorn presents a more sustainable "sow-and-harvest" alternative, free from pesticide and mycotoxin residue risks, while also enhances biodiversity from the field to the table. Full article

Understory vegetation plays a pivotal role in enhancing forest biodiversity, and its restoration is crucial for sustainable forest development, energy flow, and nutrient cycling. However, the dynamics of the biomass, diversity, and species composition of understory vegetation in plantations in south China, along with their key drivers, remain poorly understood. This study investigated four mature plantation types (Pinus massoniana, Pinus caribaea, Cunninghamia lanceolata, and mixed Chinese fir–broadleaf forests) in south China through plot surveys, environmental factor measurements, and structural equation modeling (SEM) to explore the diversity, biomass allocation patterns, and driving mechanisms of understory vegetation. The results demonstrated the following. (1) The introduced Caribbean pine forests exhibited higher shrub biomass than native Masson pine forests, which was driven by their high canopy openness favoring light-demanding species (e.g., Melicope pteleifolia, IV = 33.93%), but their low mingling degree limited herb diversity. (2) Masson pine forests showed superior shrub diversity due to their random spatial distribution and higher soil total potassium (TK) content. (3) Mixed Chinese fir–broadleaf forests achieved 24.50–66.06% higher herb biomass compared to coniferous monocultures, supported by high mingling degree, random spatial configuration, and phosphorus-potassium-enriched soil, with concurrently improved herb diversity. SEM revealed that stand structure (DBH, density, mingling degree) directly drove shrub diversity by regulating light availability, while herb biomass was primarily governed by soil total phosphorus (TP) and pH. Canopy-induced light suppression negatively affected herb diversity. We recommend optimizing stand density and canopy structure through thinning and pruning to enhance light heterogeneity alongside supplementing slow-release P fertilizers in P-deficient stands. This study provides theoretical support for the multi-objective management of south China plantations, emphasizing the synergistic necessity of stand structure optimization and soil amendment. Full article

In this study, seven Pleosporaceae strains isolated from the seagrass Posidonia oceanica and the jellyfish Pelagia noctiluca in the central Tyrrhenian Sea were characterized using a polyphasic approach (morpho-physiological, molecular, and phylogenetic analyses). Based on multi-locus phylogenetic inference and morphological characters, a new species, Tamaricicola fenicei sp. nov. was proposed. Multi-locus phylogenetic analyses, using the nuclear ribosomal regions of DNA (nrITS1-nr5.8S-nrITS2, nrLSU, and nrSSU) as well as the rpb2 and tef-1α gene sequences, strongly supported the new taxon. The phylogenetic inference, estimated using Maximum Likelihood and Bayesian Inference, clearly indicates that Tamaricicola fenicei sp. nov. forms a distinct clade within the monospecific genus Tamaricicola. The antimicrobial activity of the chloroformic and butanolic extracts from malt agar cultures of the new species exhibited interesting antiviral and antibiofilm properties. In particular, a MIC of 3.0 µg/mL was observed against the Echovirus E11 in Vero-76 cells; moreover, a biofilm BIC₅₀ reduction at 53 µg/mL was observed against Staphylococcus aureus ATCC 25923. Full article

RNA methylation, particularly N6-methyladenosine (m⁶A) and 5-methylcytosine (m⁵C), functions as a pivotal post-transcriptional regulatory mechanism and plays a central role in plant growth, development, and stress responses. This review provides a systematic summary of recent advances in RNA methylation research in cucurbit crops. To date, high-throughput technologies such as MeRIP-seq and nanopore direct RNA sequencing have enabled the preliminary construction of RNA methylation landscapes in cucurbit species, revealing their potential regulatory roles in key agronomic traits, including fruit development, responses to biotic and abiotic stresses, and disease resistance. Nevertheless, this field remains in its early stages for cucurbit crops and faces several major challenges: First, mechanistic understanding is still limited, with insufficient knowledge regarding the composition and biological functions of the core protein families involved in methylation dynamics—namely, “writers,” “erasers,” and “readers.” Second, functional validation remains inadequate, as direct evidence linking specific RNA methylation events to downstream gene regulation and phenotypic outcomes is largely lacking. Third, resources are scarce; compared to model species such as Arabidopsis thaliana and rice, cucurbit crops possess limited species-specific genetic data and genetic engineering tools (e.g., CRISPR/Cas9-based gene editing systems), which significantly hampers comprehensive functional studies. To overcome these limitations, future research should prioritize the development and application of more sensitive detection methods, integrate multi-omics datasets—including transcriptomic and methylomic profiles—to reconstruct regulatory networks, and conduct rigorous functional assays to establish causal relationships between RNA methylation modifications and phenotypic variation. The ultimate objective is to fully elucidate the biological significance of RNA methylation in cucurbit plants and harness its potential for crop improvement through genetic and biotechnological approaches. Full article

Directional Antenna Modulation (DAM) utilizing 2D conformal phased arrays has been demonstrated to enable secure Multi-directional Independent Transmission (MIT) over a broad angular range. This paper proposes an unbalanced DAM technique that dynamically allocates power according to transmission distance, thereby significantly enhancing transmission efficiency in practical scenarios where receivers are located at varying distances. In particular, a high-efficiency Differential Evolution (DE) optimization algorithm integrated with an “alien species invasion” mechanism is developed to accelerate convergence and optimize the phase delays of each array element. Bit Error Rate (BER) analysis for MIT reveals superior directional security compared to traditional methods, with conformal arrays providing wider angular coverage and spherical sparse arrays overcoming the half-wavelength spacing limitation. The simulation results validate that the proposed system achieves simultaneous secure transmissions in multiple directions while maintaining a BER below −40 dB. Full article

Background/Objectives: While morphological similarity and incomplete specimens pose a challenge to the precise identification of Coelogyne orchids, accurate species and genus assignment is essential for conservation and CITES enforcement. This study evaluated the efficacy of five DNA barcode regions—rbcL, matK, trnH-psbA, atpF-atpH, and ITS2—and their combinations for species- and genus-level discrimination within the genus Coelogyne, aiming to develop a rapid and simple diagnostic tool for use by customs officers and trade inspectors. This is the first comprehensive comparative analysis of these five barcode regions specifically within Coelogyne, a genus underrepresented in molecular identification studies, and the first to propose multi-locus combinations for potential practical use. This study identified DNA barcode regions with high resolution and reliability, providing a solid basis for practical identification kits. Such tools will enhance CITES enforcement by enabling rapid detection of Coelogyne species in trade, directly supporting their conservation and contributing to the reduction in illegal orchid trade. Methods: Using a CTAB protocol, genomic DNA was extracted from leaf samples belonging to 19 Coelogyne species. Sanger sequencing was performed after PCR amplification using published primer sets for every barcode region. Sequences were modified in BioEdit, and BLASTn (accessed 15 June 2025) was used to compare them to GenBank (NCBI Nucleotide). Amplification efficiency was calculated per locus. Species and genus identification success rates were determined by the congruence of top BLAST hits with morphologically pre-identified taxa. Multi-barcode combinations (matK + rbcL, ITS2 + matK, matK + trnH-psbA, rbcL + trnH-psbA, and matK + rbcL + trnH-psbA) were also assessed. Results: With rbcL, atpF-atpH, and ITS2 yielding ≤11%, the highest single-locus species identification rates were for trnH-psbA (21%) and matK (16%). Among single-locus barcodes, matK showed the highest performance, with 84% genus assignment. ITS2 reached 27%, but genus-level resolution remained limited for the rbcL, trnH-psbA and atpF-atpH barcodes. Multi-barcode approaches maintained species resolution: matK + rbcL + trnH-psbA, matK + rbcL, and matK + trnH-psbA correctly identified 16% of species and achieved 74–79% genus assignment. Conclusions: No single locus achieves robust species discrimination in Coelogyne, but trnH-psbA, matK and atpF-atpH provide the best single-marker performance. Using the matK locus alone, in combination with either trnH-psbA or rbcL, or all three together ensures consistent genus-level identification and significantly improves taxonomic resolution. This study introduces a novel multi-locus barcode strategy tailored to Coelogyne, offering a practical solution for identification and enforcement. While promising, this approach represents a potential application that requires further validation before routine implementation. Full article

Background/Objectives: In an era of increasing bacterial resistance, Enterococcus, as a reservoir of antibiotic resistance genes, poses a serious threat to public health. Methods: This study conducted antibiotic susceptibility tests, whole-genome sequencing, and bioinformatics analysis on 89 Enterococcus isolates from chickens, pigs, cattle, and sheep in Ningxia Autonomous Region. Results: The resistance rates of Enterococcus to clindamycin, cefoxitin, sulfamethoxazole, and tamoxifen were all above 95%, and 96.6% (86/89) of the isolates were multi-antibiotic resistant. There were significant differences in resistance phenotypes among different species, with Enterococcus from pigs showing significantly higher resistance than those from other animals. optrA was commonly found in Enterococcus from pigs, accounting for 61.5% (8/13). ST480, ST16, ST116, and ST300 were the main MLST types, and ST16 was one of the important pathogenic Enterococcus types. Conclusions: The study revealed the occurrence of inter-species transmission events of Enterococcus. In conclusion, this study comprehensively described the resistance spectrum, sequence characteristics, and transmission features of resistance genes in Enterococcus isolated from farm animals, and emphasized the possibility of the spread of resistance genes carried by Enterococcus from farm animals to humans. Full article