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• Wood density is the product of carbon allocation for structural growth and reflects the trade-off between mechanical support and water conductivity. We tested a conceptual framework based on the assumption that micro-density depends on direct and indirect relationships with endogenous and exogenous factors. • The dynamics of wood formation, including timings and rates of cell division, cell enlargement, and secondary wall deposition, were assessed from microcores collected weekly between 2002 and 2016 from five black spruce stands located along a latitudinal gradient in Quebec, Canada. Cell anatomy and micro-density were recorded by anatomical analyses and X-ray measurements. • Our structural equation model explained 80% of micro-density variation within the tree-ring with direct effects of wall thickness (σ = 0.61), cell diameter (σ = -0.51), and photoperiod (σ = -0.26). Wood formation dynamics had an indirect effect on micro-density. Micro-density increased under longer periods of cell-wall deposition and shorter durations of enlargement. • Our results fill a critical gap in understanding the relationships underlying micro-density variation in conifers. We demonstrated that short-term responses to environmental variations could be overridden by plastic responses that modulate cell differentiation. Our results point to wood formation dynamics as a reliable predictor of carbon allocation in trees.

Ferns and fern allies have low photosynthetic rates compared with seed plants. Their photosynthesis is thought to be limited principally by physical CO2 diffusion from the atmosphere to chloroplasts. The aim of this study was to understand the reasons for low photosynthesis in species of ferns and fern allies (Lycopodiopsida and Polypodiopsida). We performed a comprehensive assessment of the foliar gas-exchange and mesophyll structural traits involved in photosynthetic function for 35 species of ferns and fern allies. Additionally, the leaf economics spectrum (the interrelationships between photosynthetic capacity and leaf/frond traits such as leaf dry mass per unit area or nitrogen content) was tested. Low mesophyll conductance to CO2 was the main cause for low photosynthesis in ferns and fern allies, which, in turn, was associated with thick cell walls and reduced chloroplast distribution towards intercellular mesophyll air spaces. Generally, the leaf economics spectrum in ferns follows a trend similar to that in seed plants. Nevertheless, ferns and allies had less nitrogen per unit DW than seed plants (i.e. the same slope but a different intercept) and lower photosynthesis rates per leaf mass area and per unit of nitrogen.

Diffusion of CO2 from the leaf intercellular air space to the site of carboxylation (g m) is a potential trait for increasing net rates of CO2 assimilation (A net), photosynthetic efficiency, and crop productivity. Leaf anatomy plays a key role in this process; however, there are few investigations into how cell wall properties impact g m and A net. Online carbon isotope discrimination was used to determine g m and A net in Oryza sativa wild-type (WT) plants and mutants with disruptions in cell wall mixed-linkage glucan (MLG) production (CslF6 knockouts) under high- and low-light growth conditions. Cell wall thickness (T cw), surface area of chloroplast exposed to intercellular air spaces (S c), leaf dry mass per area (LMA), effective porosity, and other leaf anatomical traits were also analyzed. The g m of CslF6 mutants decreased by 83% relative to the WT, with c. 28% of the reduction in g m explained by S c. Although A net/LMA and A net/Chl partially explained differences in A net between genotypes, the change in cell wall properties influenced the diffusivity and availability of CO2. The data presented here indicate that the loss of MLG in CslF6 plants had an impact on g m and demonstrate the importance of cell wall effective porosity and liquid path length on g m.

To achieve the green and efficient processing of weak rigid large thin-walled aerospace parts, mirror milling systems are replacing traditional processing methods. A novel dual-robot mirror milling system consisting of a machining hybrid robot, supporting hybrid robot, and fixture is presented in this study. The cutter and the flexible supporting head are installed at the end of the machining robot and the supporting robot respectively. Because the deformation and vibration of the workpiece are directly affected by the collaborative performance of the cutter and the supporting head, the key problem is how to achieve collaborative machining by the cutter and the flexible supporting head in equal wall thickness machining. A collaborative machining method is proposed by establishing a relative pose relationship between the cutter and the supporting head. In this method, the cutter trajectory of the machining robot is generated in real time according to the end trajectory of the off-line planning supporting robot and the preset machining parameters. Next, the control parameters of each driving motor are obtained by the kinematics for the machining robot. A dual-robot endmost geometrical pose is used to obtain the machining wall thickness via contact-type online measurement for replacing ultrasonic thickness measurement systems. The wall thickness error is compensated by the machining robot for accurately controlling the machining thickness. Finally, a triangular grid is machined to verify the effectiveness of the proposed machining method in the proposed mirror milling system.

In order to obtain a lightweight, high-strength, and customizable cellular structure to meet the needs of modern production and life, the mechanical properties of four thickness gradient honeycomb structures were studied. In this paper, four types of honeycomb structure specimens with the same porosity and different Poisson’s ratios were designed and manufactured by using SLA 3D-printing technology, including the honeycomb, square honeycomb, quasi-square honeycomb, and re-entrant honeycomb structures. Based on the plane compression mechanical properties and failure mode analysis of these specimens, the thickness gradient is applied to the honeycomb structure, and four structural forms of the thickness gradient honeycomb structure are formed. The experimental results show that the thickness gradient honeycomb structure exhibits better mechanical properties than the honeycomb structure with a uniform cellular wall thickness. In the studied thickness gradient honeycomb structure, the mechanical properties of the whole structure can be significantly improved by increasing the thickness of cell walls at the upper and lower ends of the structure. The wall thickness, arrangement order, shape, and Poisson’s ratio of the cell all have a significant impact on the mechanical properties of the specimens. These results provide an effective basis for the design and application of cellular structures in the future.

Polymethyl methacrylate (PMMA) is widely used in microfluidic device fabrication due to its chemical resistance, low cost, optical transparency, and manufacturing compatibility. However, limited research exists on wall deformations and the minimum achievable wall thickness between machined channels in PMMA via micro-milling. As microfluidic devices require tightly spaced features, identifying the minimum machinable wall thickness is essential for miniaturization and multifunctional integration, enabling rapid and reproducible biomedical testing. This study presents experimental data and finite element modeling on wall deformation characteristics—wall deviation angle, average wall thickness, and minimum machinable wall thickness—between micro-milled PMMA channels. Micro end-milling was performed with varying feed rates, wall thicknesses (50 μm, 100 μm, 150 μm), and milling strategies (direct, radial, axial depth). ANOVA was used to assess parameter influence, and finite element modeling simulated wall bending under the radial depth strategy. Results show that wall thickness, feed rate, and milling strategy significantly affect wall deviation and thickness. Experimental and simulation data revealed consistent trends: 50 μm walls showed cracking, base fractures, and geometric deviations, while 100 μm and 150 μm walls retained structural integrity. A minimum wall thickness of 150 μm is necessary to ensure reliable sealing in microfluidic devices.

Despite great progress of lithium-sulfur (Li-S) battery performance at the laboratory-level, both key parameters and challenges at cell scales to achieve practical high energy density require high-sulfur-loading cathodes and lean electrolytes. Herein, a novel carbon foam integrated by hollow carbon bubble nanoreactors with ultrahigh pore volume of 6.9 cm 3 ·g −1 is meticulously designed for ultrahigh sulfur content up to 96 wt.%. Tailoring polysulfide trapping and ion/electron transport kinetics during the charge-discharge process can be achieved by adjusting the wall thickness of hollow carbon bubbles. And a further in-depth understanding of electrochemical reaction mechanism for the cathode is impelled by the in-situ Raman spectroscopy. As a result, the as-prepared cathode delivers high specific capacitances of 1,269 and 695 mAh·g −1 at 0.1 and 5 C, respectively. Furthermore, Li-S pouch cells with high areal sulfur loading of 6.9 mg·cm −2 yield exceptional practical energy density of 382 Wh·kg −1 under lean electrolyte of 3.5 µL·mg −1 , which demonstrates the great potential for realistic high-energy Li-S batteries.

The T-shaped tube is a common component in aviation pipeline systems and has broad application prospects. However, the severe wall thickness thinning has been the bottleneck problem restricting the application of T-shaped tubes. In order to avoid rupture due to excessive thinning and improve the forming quality, a new rubber compound-forming method combined with the flanging and bulging of the T-shaped tube using a prefabricated hole is proposed. The optimization model of the prefabricated hole is established based on the geometric analysis method and the incremental finite element method. The optimal prefabricated hole is achieved through two iteration optimizations. The experiments for the compound-forming method are carried out to reveal the forming height and the wall thickness distribution mechanism. Both the simulation and experiment results are in good agreement, the numerical simulation results with the optimal prefabricated hole are that the maximum thickening rate is 45.60% and the maximum thinning rate is 22.93%, and the experimental results with the optimal prefabricated hole are that the maximum thickening rate is 48.67% and the maximum thinning rate is 16.67% which are satisfied with the requirements of practical production with the maximum thickening rate no more than 50% and the maximum thinning rate no more than 30%. The new compound-forming method using the prefabricated hole could effectively avoid fracture on the branch’s top. The comparison results are further verified to be the correctness of the prefabricated hole optimization model and the effectiveness of the new compound-forming method.

X80 steel is a material with high strength and good toughness, which is widely used in long-distance natural gas pipelines. Pipelines will have different wall thicknesses, depending on the safety level requirements of different regions. Two sections of pipes with different wall thickness form unequal wall thickness of pipeline (UWTP) that is joined together by welding. UWTP pass through some geohazard areas, such as landslides. The frequency of landslides is extremely high in mountainous areas, which can seriously affect the safe operation of UWTP. In this paper, a model of a 12.8 mm wall pipe section and a 15.6 mm wall pipe section are linked by girth welds. The strain between the pipe section and the weld was quantitatively analyzed. The results show that the strain at the girth weld in the 3 o’clock direction of the pipe increases sharply. The strain in the 9 o’clock direction of the pipe is generally lower than the strain in the 3 o’clock direction. The strain value of the 12.8mm wall thickness pipe section is generally greater than the strain value of the 15.6mm wall thickness pipe section.

In conventional electromagnetic tube expansion (EMTE), the wall thickness of the tube decreases significantly because the electromagnetic force is mainly in the radial direction. To solve this problem, this paper proposes a new method named electromagnetic tube expansion with axial compression (EMTEAC). Besides the driving coil, we introduce a coil at each end of the tube to generate axial electromagnetic force on the tube. We use the finite element method to analyze the distribution of the magnetic flux density and the electromagnetic force generated by the three coils in series. The simulation results show that the axial electromagnetic force generated by EMTEAC is about 7 times that generated by conventional electromagnetic tube expansion, which enhances material flow when the tube is expanding. The effectiveness of the method is verified by a series of experiments. The experimental results show that EMTEAC reduces the decrease in wall thickness from 27 to 19%.