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From continuous high‐frequency and high‐resolution observations of temperature, salinity, current and microstructure in the northern South China Sea during 28–31 May 2021, we found that the transition layer (TL) experienced a regular diurnal vertical fluctuation of ∼20–30 m, likely associated with the displacements of the mixed layer (ML) and tidal shear in the TL. Specifically, surface cooling (heating) caused an erosion (enhancement) of thermal stratification and facilitated (hindered) convection, rapidly deepening (shoaling) the ML and causing corresponding vertical displacements in the TL. The mixture of diurnal and semidiurnal tides, together with internal tides and tidal rectification, resulted in a diurnally varying large shear in the TL. This enhanced shear caused the TL to further descend along with the rapid thickening of the ML, while the relatively weaker shear slowed the uplift of the TL with a rapid shoaling of the ML and resulted in its gradual shoaling. Plain Language Summary Oceanic transition layer (TL) is the interface between the highly turbulent surface mixed layer (ML) and the weakly turbulent interior layer. The daily variations in the TL are significantly related to near‐surface and interior processes, such as thermal stratification and tidal motions. However, the driving mechanisms cannot be quantitatively evaluated without high‐resolution spatial and temporal observations. In this study, hourly observations were comprehensively recorded over 3 days in the northern South China Sea, and new results were obtained in regard to the dual effects of surface forcing and interior dynamics driving the vertical displacements of the TL. Specifically, diurnal variations in the upper boundary of the TL, that is, the base of the surface ML, are mainly controlled by surface forcing. However, the lower boundary of the TL is significantly modulated by tidal shear in association with a mixture of diurnal and semidiurnal tides, internal tides and tidal rectification. Our study provided observational evidence and viewpoints regarding the daily TL variations. Key Points Vertical displacements of the transition layer aligned with those of mixed layer driven by surface heating/cooling and the Langmuir cell A mixture of diurnal and semidiurnal tides, internal tides and tidal rectification resulted in large shear in the transition layer Tidal shear modulated the depth of the transition layer by slowing the ascent or causing the layer to descend further

Surface defect detection for printed circuit board (PCB) is indispensable for managing PCB production quality. However, automatic detection of PCB surface defects is still a challenging task because, even within the same category of surface defect, defects present great differences in morphology and pattern. Although many computer vision-based detectors have been established to handle these problems, current detectors struggle to achieve high detection accuracy, fast detection speed and low memory consumption simultaneously. To address those issues, we propose a cost-effective deep learning (DL)-based detector based on the cutting-edge YOLOv4 to detect PCB surface defect quickly and efficiently. The YOLOv4 is improved upon with respect to its backbone network and the activation function in its neck/prediction network. The improved YOLOv4 is evaluated with a customized dataset, collected from a PCB factory. The experimental results show that the improved detector achieved a high performance, scoring 98.64% on mean average precision (mAP) at 56.98 frames per second (FPS), outperforming the other compared SOTA detectors. Furthermore, the improved YOLOv4 reduced the parameter space of YOLOv4 from 63.96 M to 39.59 M and the number of multiply-accumulate operations (Madds) from 59.75 G to 26.15 G.

Ultra-precision machining (UPM) is crucial for producing parts with functional surfaces featuring nano textures, yet it faces challenges in generating such textures. This paper explores the potential of magnetic field-assisted UPM to overcome these challenges by leveraging magnetophoresis to generate nanotextures and thoroughly investigating the importance of cutting velocity on magnetophoresis in diamond cutting. Experimental results from cutting force, surface profile, surface topography, and atomic force microscopy images demonstrate that magnetic fields enable nanotexture generation on aluminum alloys surfaces in diamond cutting. Also, increasing cutting speed in diamond cutting under a magnetic field enhances magnetophoresis. This study highlights the advantages of integrating magnetophoresis for advanced nanotexture fabrication in UPM and emphasizes strategies for control cutting speed to achieve nanotextures.

Topological properties of materials are typically presented in momentum space. Here, we demonstrate a universal mapping of topological singularities from momentum to real space. By exciting Dirac-like cones in photonic honeycomb (pseudospin-1/2) and Lieb (pseudospin-1) lattices with vortex beams of topological charge  l , optimally aligned with a given pseudospin state s , we directly observe topological charge conversion that follows the rule l  →  l + 2 s . Although the mapping is observed in photonic lattices where pseudospin-orbit interaction takes place, we generalize the theory to show it is the nontrivial Berry phase winding that accounts for the conversion which persists even in systems where angular momentum is not conserved, unveiling its topological origin. Our results have direct impact on other branches of physics and material sciences beyond the 2D photonic platform: equivalent mapping occurs for 3D topological singularities such as Dirac-Weyl synthetic monopoles, achievable in mechanical, acoustic, or ultracold atomic systems, and even with electron beams. Topological properties of materials are typically presented in momentum space. Here, the authors show a universal mapping of topological singularities from momentum to real space, potentially applicable to a wide range of systems.

Background Bivalves have independently evolved a variety of symbiotic relationships with chemosynthetic bacteria. These relationships range from endo- to extracellular interactions, making them ideal for studies on symbiosis-related evolution. It is still unclear whether there are universal patterns to symbiosis across bivalves. Here, we investigate the hologenome of an extracellular symbiotic thyasirid clam that represents the early stages of symbiosis evolution. Results We present a hologenome of Conchocele bisecta (Bivalvia: Thyasiridae) collected from deep-sea hydrothermal vents with extracellular symbionts, along with related ultrastructural evidence and expression data. Based on ultrastructural and sequencing evidence, only one dominant Thioglobaceae bacteria was densely aggregated in the large bacterial chambers of C. bisecta , and the bacterial genome shows nutritional complementarity and immune interactions with the host. Overall, gene family expansions may contribute to the symbiosis-related phenotypic variations in different bivalves. For instance, convergent expansions of gaseous substrate transport families in the endosymbiotic bivalves are absent in C. bisecta . Compared to endosymbiotic relatives, the thyasirid genome exhibits large-scale expansion in phagocytosis, which may facilitate symbiont digestion and account for extracellular symbiotic phenotypes. We also reveal that distinct immune system evolution, including expansion in lipopolysaccharide scavenging and contraction of IAP (inhibitor of apoptosis protein), may contribute to the different manners of bacterial virulence resistance in C. bisecta . Conclusions Thus, bivalves employ different pathways to adapt to the long-term co-existence with their bacterial symbionts, further highlighting the contribution of stochastic evolution to the independent gain of a symbiotic lifestyle in the lineage.

Composite photocatalyst materials have potential application value in the field of environmental protection, especially in the degradation of water pollutants. In this paper, Ag-BiOI composite photocatalyst materials were prepared by deposition method on BiOI flower-like microspheres prepared by microwave solvothermal method. BiOI flower balls are stacked by interlaced nanosheets, and Ag nanoparticles are attached to the surface of BiOI microspheres. This paper explores the effect of Ag loading on the photocatalytic performance of composite materials through variable control. The research results show that as the Ag content increases, the degradation rate of RhodamineB (RhB) and Ciprofloxacin (CIP) of the sample under visible light irradiation increases. The 4% Ag/BiOI composite photocatalyst exhibits the best degradation performance for Rhodamine B solution (RhB, 20 mg/L) and Ciprofloxacin solution (CIP, 10 mg/L), achieving degradation rates of 80.4% and 80.0%, respectively, which is five times higher than that of BiOI before loading. This significantly improves the treatment efficiency of organic pollutants.In addition, excessive Ag particle compounding will reduce the light absorption performance of the sample, thereby reducing the catalytic degradation characteristics of the material. Furthermore, the recyclability of the 4% Ag-BiOI composite was evaluated, and it was found that after five cycles of use, the photocatalytic activity remained stable, indicating excellent reusability of the material. Finally, this article discusses the catalytic degradation mechanism of Ag composite catalyst materials based on experimental results, and provides a design strategy for loading heavy metals to improve the catalytic performance of materials.Article highlightsAdding a 4% silver content to BiOI microspheres significantly boosts their ability to break down harmful dyes and antibiotics in water under sunlight.The optimal silver-loaded composite not only degrades pollutants more efficiently but also maintains its effectiveness over multiple uses, highlighting its practical value for water treatment.While increasing silver improves the material's performance up to a point, too much can actually hinder its light absorption and reduce the overall efficiency.

Animal behavior is linked to the gene regulatory network (GRN) coordinating gene expression in the brain. Eusocial honeybees, with their natural behavioral plasticity, provide an excellent model for exploring the connection between brain activity and behavior. Using single-nucleus RNA sequencing and spatial transcriptomics, we analyze the expression patterns of brain cells associated with the behavioral maturation from nursing to foraging. Integrating spatial and cellular data uncovered cell-type and spatial heterogeneity in GRN organization. Interestingly, the stripe regulon is explicitly activated in foragers’ small Keyon cells, which are implicated in spatial learning and navigation. When worker age is controlled in artificial colonies, stripe and its key targets remained highly expressed in the KC regions of bees performing foraging tasks. These findings suggest that specific GRNs coordinate individual brain cell activity during behavioral transitions, shedding light on GRN-driven brain heterogeneity and its role in the division of labor of social life. Honeybee behavioral plasticity provides a model to study how brain gene networks regulate behavior. Here, authors show stripe activation in Kenyon cells links gene regulatory networks to behavioral maturation via spatial-cellular coordination.

During cerebral ischemia, adenosine triphosphate (ATP) is released into the extracellular matrix from damaged neurons and glial cells, functioning as a danger signal. However, the involvement of ATP/P2X7 signaling in regulating the infiltrated lymphocytes during ischemia-reperfusion (IR) injury remain unclear. The expression level of P2X7 was evaluated in infiltrated lymphocytes from experimental stroke mice. To further elucidate the role of P2X7 signaling in infiltrated immune cells during ischemic stroke, P2X7-knockout (KO) mice and Rag2 mice were utilized. Additionally, experiments were conducted to explore the underlying mechanisms. Flow cytometry analysis revealed that the expression of P2X7 was mainly expressed in CD4 and CD8 T cells among the infiltrated lymphocytes in stroke lesions of the mice. P2X7-KO mice exhibited smaller infarct sizes and improved neurological function compared to wild-type mice. Rag2 mice that received P2X7-KO CD4 T cells demonstrated reduced ischemic-reperfusion injury and a decreased level of IL-17A and frequency of Th17 cells compared to Rag2 mice that received wild type CD4 T cells. Transcriptome sequencing and experiments indicate that P2X7 may mediate the expression of IL-21 and regulating the synthesis of IL-17A and the differentiation of Th17 cells. We also confirmed that P2X7 receptor regulates IL-21 through STAT3 signaling. Our findings suggest that the loss of ATP/P2X7 signaling in CD4 T cells may inhibit the pSTAT3, IL-21 pathway, leading to reduced differentiation of Th17 cells and ultimately mitigating IR injury. This provides novel insights into the role of ATP/P2X7-mediated signaling in T cell inflammation during ischemic stroke.

Background The repair of bone defects remains a significant clinical challenge. Although magnesium (Mg)-based biomimetic scaffolds are widely utilized for bone defect repair, the release of Mg²⁺ ions often leads to an alkaline microenvironment, thereby adversely affecting bone regeneration. Regenerative medicine strategies that leverage the recruitment of endogenous bone marrow mesenchymal stem cells (BMSCs) offer a novel approach to treating bone defects. Methods In this study, we employed poly(L-lactic acid) (PLLA) and polyethylene glycol (PEG) as shell materials and nanomagnesium oxide (nMgO) combined with gelatin (G) as core materials to fabricate coaxial fibre membranes with a “core‒shell” structure via coaxial electrospinning technology. Additionally, we grafted the BMSC-affinitive peptide E7 (EPLQLKM) onto the fibres to achieve specific recruitment of endogenous BMSCs. Results Morphological and structural analyses confirmed the successful formation of the “core‒shell” structure of the fibre membranes. Grafting E7 peptides enhanced the hydrophilicity and mechanical properties of the fibre membranes and maintained pH stability in vitro. In vitro experiments demonstrated that the functionalized fibre membranes significantly promoted BMSC proliferation, migration, and osteogenic differentiation. When implanted into a rat cranial defect model, we observed the formation of new bone tissue and the repair of the bone defect. Conclusions E7 peptide-functionalized coaxial fibre membranes effectively facilitated bone defect repair by promoting the recruitment and osteogenic differentiation of BMSCs, demonstrating substantial potential for tissue engineering applications.

In this study, TiC particle-reinforced Cu-based composites were prepared by powder metallurgy and spark plasma sintering (SPS) techniques. The mechanical and electrical properties of TiC/Cu composites were analyzed in conjunction with micro-morphology. The results showed that: TiC was fully diffused in the Cu matrix at a sintering temperature of 900 °C. The micron-sized TiC particles were most uniformly distributed in the Cu matrix and had the best performance. At this time, the densification of 5 wt.% TiC/Cu composites reached 97.19%, and the conductivity, hardness, and compressive yield strength were 11.47 MS·m−1, 112.9 HV, and 162 MPa, respectively. The effect of TiC content on the overall properties of the composites was investigated at a sintering temperature of 900 °C. The TiC content of the composites was also found to have a significant influence on the overall properties of the composites. The best performance of the composites was obtained when the TiC mass fraction was 10%. The average values of density, hardness, yield strength and conductivity of the 10 wt.% TiC/Cu composites were 90.07%, 128.3 HV, 272 MPa and 9.98 MS·m−1, respectively. The yield strength was 272 MPa, and the compressive strain was 38.8%. With the increase in TiC content, although the yield strength increased, the brittleness increased due to more weak interfaces in the composites.