Search Results (7,593)

To evaluate the characteristics of Smith–Purcell radiation, we modified a surface current model to consider the geometrical shading effect of a grating, which was ignored in the original one, and compared it with measurements for a grating with a shallow blaze angle. According to the numerical calculations based on the surface current model with and without the shading effect, it was found that the azimuthal angular distribution, polarization components and the variation in radiation intensity with the blaze angle of the grating are predicted to show significantly different behaviors under our experimental conditions. Generating the coherent Smith–Purcell radiation using the very short electron bunch in the test accelerator, t-ACTS at the Research Center for Accelerator and Radioisotope Science, Tohoku University, we measured polarization and the angular distribution of radiation for the gratings with different blaze angles. This study supports the validity of the modified surface current model with the shading effect and will provide new insights into the evaluation of the characteristics of Smith–Purcell radiation. Full article

HPMC, regulating slurry properties, is widely used in cement-based materials. Research on the application of HPMC in gangue slurry is still in its early stages. Moreover, the interactive effects of various factors on gangue slurry performance have not been thoroughly investigated. The work examined the effects of slurry concentration (X₁), maximum gangue particle size (X₂), and HPMC dosage (X₃) on slurry performance using response surface methodology (RSM). The microstructure of the slurry was characterized via scanning electron microscopy (SEM) and polarized light microscopy (PLM), while low-field nuclear magnetic resonance (LF-NMR) was employed to analyze water distribution. Additionally, industrial field tests were conducted. The results are presented below. (1) X₁ and X₃ exhibited a negative correlation with layering degree and slump flow, while X₂ showed a positive correlation. Slurry concentration had the greatest impact on slurry performance, followed by maximum particle size and HPMC dosage. HPMC significantly improved slurry stability, imposing the minimum negative influence on fluidity. Interaction terms X₁X₂ and X₁X₃ significantly affected layering degree and slump flow, while X₂X₃ significantly affected layering degree instead of slump flow. (2) Derived from the RSM, the statistical models for layering degree and slump flow define the optimal slurry mix proportions. The gangue gradation index ranged from 0.40 to 0.428, with different gradations requiring specific slurry concentration and HPMC dosages. (3) HPMC promoted the formation of a 3D floc network structure of fine particles through adsorption-bridging effects. The spatial supporting effect of the floc network inhibited the sedimentation of coarse particles, which enhanced the stability of the slurry. Meanwhile, HPMC only converted a small amount of free water into floc water, which had a minimal impact on fluidity. HPMC addition achieved the synergistic optimization of slurry stability and fluidity. (4) Field industrial trials confirmed that HPMC-optimized gangue slurry demonstrated significant improvements in both stability and flowability. The optimized slurry achieved blockage-free pipeline transportation, with a maximum spreading radius exceeding 60 m in the goaf and a maximum single-borehole backfilling volume of 2200 m³. Full article

Hierarchical surface structuring is a critical aspect of advanced materials design, impacting fields ranging from optics to biomimetics. Among several laser-based methods for complex structuring of photo-responsive surfaces, the broadband vectorial interferometry proposed here offers unique performances. Such a method leverages a polychromatic laser source, an unconventional choice for holographic encoding, to achieve deterministic multiscale surface structuring through interference light patterning. Azopolymer films are used as photosensitive substrates. By exploring the interaction between optomechanical stress modulations at different spatial periodicities induced within the polymer bulk, we demonstrate the emergence of hierarchical Fourier surfaces composed of multiple deterministic levels. These structures range from sub-micrometer to tens of micrometers scale, exhibiting a high degree of control over their morphology. The experimental findings reveal that the optical encoding scheme significantly influences the resulting topographies. The polarization light patterns lead to more regular and symmetric hierarchical structures compared to those obtained with intensity patterns, underscoring the role of vectorial light properties in controlling surface morphologies. The proposed method is fully scalable, compatible with more complex recording schemes (including multi-beam interference), and it is applicable to a wide range of advanced technological fields. These include optics and photonics (diffractive elements, polarimetric devices), biomimetic surfaces, topographical design, information encoding, and anti-counterfeiting, offering a rapid, reliable, and versatile strategy for high-precision surface structuring at a submicrometric scale. Full article

Clarifying the coordination and impediments of social, economic, and spatial connection in rural areas is essential for advancing rural revitalization, urban-rural integration, and regional coordinated development. Utilizing the 24 counties and districts in western Hunan as case studies, we developed an evaluation index system for sustainable rural development across three dimensions: social, economic, and spatial. We employed the coupling model, coordination model, and obstacle factor model to investigate the comprehensive development level, coupling and coordination status, and obstacle factors of the villages in the study area at three temporal points: 2002, 2012, and 2022. The findings indicate the following: (1) The degree of rural development in western Hunan has escalated swiftly throughout the study period, transitioning from relative homogeneity to a heterogeneous developmental landscape, accompanied by issues such as inadequate development and regional polarization. (2) The overall rural social, economic, and spatial indices are low, and the degree of coupling has increased variably across different study periods; the average coordination degree has gradually improved over time, yet the level of coordination remains low, and spatial development is unbalanced. (3) The criterion-level impediments hindering the sustainable development of rural society, economy, and space are, in descending order, social factors, spatial factors, and economic factors. The urbanization rate, total fixed investment rate, and arable land change rate are the primary impediments in most counties and cities. The study’s findings will inform the planning of rural development in ethnic regions, promote sustainable social and spatial advancement in the countryside, and serve as a reference for rural revitalization efforts. Full article

This study evaluated birch and oak ash extracts as alternative extractants for isolating humic substances (HSs) from peat and lignite. The effects of ultrasound intensity, extraction time, and temperature were optimized using a Box–Behnken design and validated statistically. The highest HSs yields were obtained from peat with oak ash extract (pH 13.18), compared to birch ash extract (pH 12.09). Optimal process parameters varied by variant, falling within 309–391 mW∙cm⁻², 116–142 min, and 67–79 °C. HSs extracted under optimal conditions were fractionated into humic acids (HAs) and fulvic acids (FAs), and then analyzed by elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), and Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance Spectroscopy (CP/MAS ¹³C NMR). The main differences in HSs quality were influenced by raw material and fraction type. However, the use of birch ash extract consistently resulted in a higher proportion of carboxylic structures across all fractions. Overall, wood ash extract, especially from oak, offers a sustainable and effective alternative to conventional extractants, particularly for HSs isolation from lignite. Notably, HSs yield from lignite with oak ash extract (29.13%) was only slightly lower than that achieved with 0.5 M NaOH (31.02%), highlighting its practical potential in environmentally friendly extraction technologies. Full article

This study aimed to investigate the underlying mechanisms by which dandelion extract inhibits the proliferation of breast cancer MDA-MB-231 cells. Dandelion root and leaf extracts were prepared using a heat reflux method and subjected to solvent gradient extraction to obtain fractions with different polarities. MTT assays revealed that the ethyl acetate fraction exhibited the strongest inhibitory effect on cell proliferation. LC-MS analysis identified 12 potential active compounds, including sesquiterpenes such as Isoalantolactone and Artemisinin, which showed significantly lower toxicity toward normal mammary epithelial MCF-10A cells compared to tumor cells (p < 0.01). Mechanistic studies demonstrated that the extract induced apoptosis in a dose-dependent manner, with an apoptosis rate as high as 85.04%, and significantly arrested the cell cycle at the S and G2/M phases. Label-free quantitative proteomics identified 137 differentially expressed proteins (|FC| > 2, p < 0.05). GO enrichment analysis indicated that these proteins were mainly involved in cell cycle regulation and apoptosis. KEGG pathway analysis revealed that the antitumor effects were primarily mediated through the regulation of PI3K-Akt (hsa04151), JAK-STAT (hsa04630), and PPAR (hsa03320) signaling pathways. Moreover, differential proteins such as PI3K, AKT1S1, SIRT6, JAK1, SCD, STAT3, CASP8, STAT2, STAT6, and PAK1 showed strong correlation with the core components of the EA-2 fraction of dandelion. Molecular docking results demonstrated that these active compounds exhibited strong binding affinities with key target proteins such as PI3K and JAK1 (binding energy < −5.0 kcal/mol). This study elucidates the multi-target, multi-pathway synergistic mechanisms by which dandelion extract inhibits breast cancer, providing a theoretical basis for the development of novel antitumor agents. Full article

Tissue remodeling of human endometrium occurs during the menstrual cycle to prepare for embryo adhesion and invasion. The ovarian steroid hormones 17β-estradiol and progesterone control the menstrual cycle to achieve the receptive state during the “window of implantation” (WOI). Here, we focus on the human endometrial epithelium and its changes in polarity, adhesion, cytoskeletal organization and the underlying extracellular matrix enabling embryo implantation. The adhesion and invasion of the trophoblast via the apical plasma membrane of epithelial cells is a unique cell biological process, which is coupled to partial epithelial–mesenchymal transition (EMT). Given the fundamental species differences during implantation, we restrict the review mainly to the human situation and focus on cell culture systems to study the interaction between human trophoblast and endometrial cells. We summarize current knowledge based on the relatively scarce in vivo data and the steadily growing in vitro observations using various cell culture systems. Full article

Accurate detection of the atmospheric boundary layer (ABL) is important for weather forecasting, urban air quality monitoring, and agricultural and ecological protection. In this study, we propose a new method for enhancing ABL height detection accuracy by integrating multi-channel polarized lidar signals at 355 nm and 532 nm wavelengths. Radiosonde observations and ERA5 reanalysis are used to validate the lidar-derived results. By calculating the gradients of signals of different wavelengths and weighted fusion, the position of the top of the boundary layer is identified, and corresponding weights are assigned to signals of different wavelengths according to the signal-to-noise ratio of the signals to obtain a more accurate atmospheric boundary layer height. This method can effectively mitigate the influence of noise and provides more stable and accurate ABL height estimates, particularly under complex aerosol conditions. Three case studies of ABL height detection over the Beijing region demonstrate the effectiveness and reliability of the proposed method. The fused ABLHs were found to be consistent with the sounding data and ERA5. This research offers a robust approach to enhancing ABL height detection and provides valuable data support for meteorological studies, pollution monitoring, and environmental protection. Full article

Tissue engineering enables autologous reconstruction of human tissues, addressing limitations in tissue availability and immune compatibility. Several tissue engineering techniques, such as self-assembly, rely on or benefit from extracellular matrix (ECM) secretion by fibroblasts to produce biomimetic scaffolds. Models have been developed for use in humans, such as skin and corneas. Ascorbic acid (vitamin C, AA) is essential for collagen biosynthesis. However, AA is chemically unstable in culture, with a half-life of 24 h, requiring freshly prepared AA with each change of medium. This study aims to demonstrate the functional equivalence of 2-phospho-L-ascorbate (2PAA), a stable form of AA, for tissue reconstruction. Dermal, vaginal, and bladder stroma were reconstructed by self-assembly using tissue-specific protocols. The tissues were cultured in a medium supplemented with either freshly prepared or frozen AA, or with 2PAA. Biochemical analyses were performed on the tissues to evaluate cell density and tissue composition, including collagen secretion and deposition. Histology and quantitative polarized light microscopy were used to evaluate tissue architecture, and mechanical evaluation was performed both by tensiometry and atomic force microscopy (AFM) to evaluate its macroscopic and cell-scale mechanical properties. The tissues produced by the three ascorbate conditions had similar collagen deposition, architecture, and mechanical properties in each organ-specific stroma. Mechanical characterization revealed tissue-specific differences, with tensile modulus values ranging from 1–5 MPa and AFM-derived apparent stiffness in the 1–2 kPa range, reflecting the nonlinear and scale-dependent behavior of the engineered stroma. The results demonstrate the possibility of substituting AA with 2PAA for tissue engineering. This protocol could significantly reduce the costs associated with tissue production by reducing preparation time and use of materials. This is a crucial factor for any scale-up activity. Full article

The escalating demand for efficient thermal management in lithium-ion batteries necessitates precise characterization of their thermal behavior under diverse operating conditions. This study develops a three-dimensional (3D) electrochemical–thermal coupling model grounded in porous electrode theory and energy conservation principles. The model solves multi-physics equations such as Fick’s law, Ohm’s law, and the Butler–Volmer equation, to resolve coupled electrochemical and thermal dynamics, with temperature-dependent parameters calibrated via the Arrhenius equation. Simulations under varying discharge rates reveal that high-rate discharges exacerbate internal heat accumulation. Low ambient temperatures amplify polarization effects. Forced convection cooling reduces surface temperatures but exacerbates core-to-surface thermal gradients. Structural optimization strategies demonstrate that enhancing through-thickness thermal conductivity reduces temperature differences. These findings underscore the necessity of balancing energy density and thermal management in lithium-ion battery design, proposing actionable insights such as preheating protocols for low-temperature operation, optimized cooling systems for high-rate scenarios, and material-level enhancements for improved thermal uniformity. Full article

The search for substances that increase the immunity of bees is becoming a necessity in the era of various environmental threats and the declining immunocompetence of these insects. Therefore, we tested the biological and physicochemical properties of 7-diethylamino-4-hydroxycoumarin (7DOC). In a cage test, two groups of bees were created: a control group fed with sugar syrup and an experimental group fed with sugar syrup with the addition of 7DOC. In each group, the longevity of the bees was determined and the protein concentrations and antioxidant activities in the bees’ hemolymph were determined. The bees fed with 7DOC lived 2.7 times longer than those in the control group. The protein concentrations and activities of SOD, CAT, GPx and GST, as well as the TAC levels, were significantly higher in the hemolymph of the supplemented workers. To confirm these potent biological properties of 7DOC, the UV-Vis spectra, emission and excitation of fluorescence, synchronous spectra and finally the fluorescence lifetimes of this compound were measured using the time-correlated single photon counting method, in various environments differing in polarity and in the environment applied in bee research. This compound was shown to be sensitive to changes in solvent polarity. The spectroscopic assays were complemented with crystallographic tests of the obtained monocrystals of the aforementioned compounds, which attested to the aggregation effects observed in the spectra measurements for the selected coumarin. The research results confirm that this compound has the potential to be implemented in apiary management, which will be our application goal, but further research into apiary conditions is required. Full article

Image-assisted digital shade guides are increasingly popular for shade matching; however, research on their accuracy remains limited. This study aimed to compare the accuracy and reliability of color coordination in image-assisted digital shade guides constructed using calibrated images of their shade tabs captured by a mirrorless camera (Canon, Tokyo, Japan) (MC-DSG) and a smartphone camera (Samsung, Seoul, Korea) (SC-DSG), using a spectrophotometer as the reference standard. Twenty-nine VITA Linearguide 3D-Master shade tabs were photographed under controlled settings with both cameras equipped with cross-polarizing filters. Images were calibrated using Adobe Photoshop (Adobe Inc., San Jose, CA, USA). The L* (lightness), a* (red-green chromaticity), and b* (yellow-blue chromaticity) values, which represent the color attributes in the CIELAB color space, were computed at the middle third of each shade tab using Adobe Photoshop. Specifically, L* indicates the brightness of a color (ranging from black [0] to white [100]), a* denotes the position between red (+a*) and green (–a*), and b* represents the position between yellow (+b*) and blue (–b*). These values were used to quantify tooth shade and compare them to reference measurements obtained from a spectrophotometer (VITA Easyshade V, VITA Zahnfabrik, Bad Säckingen, Germany). Mean color differences (∆E₀₀) between MC-DSG and SC-DSG, relative to the spectrophotometer, were compared using a independent t-test. The ∆E₀₀ values were also evaluated against perceptibility (PT = 0.8) and acceptability (AT = 1.8) thresholds. Reliability was evaluated using intraclass correlation coefficients (ICC), and group differences were analyzed via one-way ANOVA and Bonferroni post hoc tests (α = 0.05). SC-DSG showed significantly lower ΔE₀₀ deviations than MC-DSG (p < 0.001), falling within acceptable clinical AT. The L* values from MC-DSG were significantly higher than SC-DSG (p = 0.024). All methods showed excellent reliability (ICC > 0.9). The findings support the potential of smartphone image-assisted digital shade guides for accurate and reliable tooth shade assessment. Full article

Sideroxylon cinereum, an endemic Mauritian fruit, was investigated through comprehensive chemical analyses of solvent extracts from its pulp and seed. Dried fruit materials were subjected to maceration using water and organic solvents including methanol, ethanol, propanol, and acetone to obtain extracts of varying polarity. Preliminary phytochemical screening revealed the presence of several bioactive compounds, with pulp extracts generally richer in phytochemicals than seed extracts. UV-Vis and FTIR analyses confirmed key organic constituents, including sulfoxides in seeds. HPLC quantification showed notable citric acid content in the pulp (15.63 mg/g dry weight). Antioxidant assays indicated that organic solvent extracts of the pulp had superior free radical scavenging activity, while the seed’s aqueous extract exhibited the highest ferric reducing power. GC–MS profiling identified a diverse bioactive profile rich in terpenes, notably lanosterol acetate (>45% in both pulp and seeds). It is important to note that these findings are based on solvent extracts, which may differ from the phytochemical composition of the whole fruit as typically consumed. Among the extracts, aqueous fractions are likely the most relevant to dietary intake. Overall, the extracts of Sideroxylon cinereum pulp and seed show potential as sources of bioactive compounds for functional product development. Full article

In this article, femtosecond laser scanning was used to create heterojunctions between silver nanowire (Ag NW) and graphene oxide (GO), resulting in a mechanical and electrical interconnection. Surface plasmon resonances (SPRs) were generated on the nanowire surface by using femtosecond laser irradiation, producing a periodically excited electric field along the Ag NWs. This electric field then interfered with the femtosecond laser field, creating strong localized heating effects, which melted the Ag NW and GO, leading to mechanical bonding between the two. The formation of these heterostructures was attributed to the transfer of plasmon energy from the Ag NW to the adjacent GO surface. Since the connection efficiency of the nanowires is closely related to the specific location and the polarization direction of the laser, FDTD simulations were conducted to model the electric field distribution on the surface of Ag NW and GO structures under different laser polarization directions, varying the lengths and diameters of the nanowires. Finally, the resistance changes of the printed Ag NW paths on the GO thin film after femtosecond laser irradiation were investigated. It was found that laser bonding could reduce the resistance of the Ag NW-GO heterostructures by two orders of magnitude, further confirming the formation of the junctions. Full article

This work addresses for the first time the effect of anode serpentine channel depth on Methanol Electrolysis Cells (MECs) and Direct Methanol Fuel Cells (DMFCs) for improving performance of both devices. Anode plates with serpentine flow fields of 0.5 mm, 1.0 mm and 1.5 mm depths are designed and tested in single-cells to compare their behaviour. Performance was evaluated through methanol crossover, polarization and power density curves. Results suggest shallower channels enhance mass transfer efficiency reducing MEC energy consumption for hydrogen production at 40 mA∙cm⁻² by 4.2%, but increasing methanol crossover by 30.3%. The findings of this study indicate 1.0 mm is the best depth among those studied for a MEC with 16 cm² of active area, while 0.5 mm is the best for a DMFC with the same area with an increase in peak power density of 14.2%. The difference in results for both devices is attributed to higher CO₂ production in the MEC due to its higher current density operation. This increased CO₂ production alters anode two-phase flow, partially hindering the methanol oxidation reaction with shallower channels. These findings underscore the critical role of channel depth in the efficiency of both MEC and DMFC single-cells. Full article