We investigate the angular dynamics of a single spheroidal particle with large particle-to-fluid density ratio in simple shear flows, focusing on the influence of the fluid-inertial torque induced by slip velocity. A linear stability analysis is performed to examine how the fluid-inertial torque, viscous shear torque and particle inertia affect the various stable rotation modes, including logrolling, tumbling and aligning modes. As particle inertia increases, bistable or tristable rotation modes emerge depending on initial conditions. For prolate spheroids, three distinct stable-mode regimes are identified, i.e. logrolling, tumbling and tumbling–logrolling (TL). The presence of these modes depends on particle shape and inertia. For oblate spheroids, when the Stokes number is small, we observe monostable modes (logrolling, tumbling and aligning) and bistable modes (TL, aligning–logrolling) varying with different factors. As Stokes number increases, the tristable mode (aligning–tumbling–logrolling) of oblate spheroids appears. These results of the stability analysis further highlight the intricate and significant effect of fluid-inertial torque compared with the results in the absence of fluid-inertial torque. When we apply fluid-inertial torque to the point-particle model, we reproduce the stable rotation modes observed in particle-resolved simulations, which validates the present stability analysis.

The mandible is crucial for human physiological functions, as well as facial esthetics and expressions. The mandibular reconstruction surgery has dual challenges of restoration of both facial form and physiological function, which demands high precision in positioning and orientation of the bone graft. The traditional manual surgery heavily relies on surgeon’s experience. Although the computer image-guided surgery improves the positioning accuracy, the manual manipulation is still difficult to achieve precise spatial orientation of objects, resulting in unsatisfactory intraoperative execution of preoperative surgical design. This paper integrates computer image navigation and robotic technology to assist mandible reconstruction surgery, which empowers surgeons to achieve precise spatial localization and orientation adjustment of bone grafts. The kinematic analysis is conducted, and an improved Iterative Closest Point (ICP) algorithm is proposed for spatial registration. A novel hand-eye calibration method for multi-arm robot and spatial registration of free bone blocks are proposed. The precision experiment of the image-guided navigation and the animal experiments are carried out. The impact of registration point numbers on spatial registration accuracy is analyzed. The results show the feasibility of the robot-assisted navigation for mandibular reconstruction surgery. The robotic system can improve the orientation accuracy of bone blocks to enhance the effectiveness of surgery.

The heating effect of electromagnetic waves in ion cyclotron range of frequencies (ICRFs) in magnetic confinement fusion device is different in different plasma conditions. In order to evaluate the ICRF heating effect in different plasma conditions, we conducted a series of experiments and corresponding TRANSP simulations on the EAST tokamak. Both simulation and experimental results show that the effect of ICRF heating is poor at low core electron density. The decrease in electron density changes the left-handed electric field near the resonant layer, resulting in a significant decrease in the power absorbed by the hydrogen fundamental resonance. However, quite a few experiments must be performed in plasma conditions with low electron density. It is necessary to study how to make ICRF heating best in low electron density plasma. Through a series of simulation scans of the parallel refractive index (n//) of the ICRF antenna, it is concluded that the change of the ICRF antenna n// will lead to the change of the left-handed electric field, which will change the fundamental absorption of ICRF power by the hydrogen minority ions. Fully considering the coupling of ion cyclotron wave at the tokamak boundary and the absorption in the plasma core, optimizing the ICRF antenna structure and selecting appropriate parameters such as parallel refractive index, minority ion concentration, resonance layer position, plasma current and core electron temperature can ensure better heating effect in the ICRF heating experiments in the future EAST upgrade. These results have important implications for the enhancement of the auxiliary heating effect of EAST and other tokamaks.

This study presents a novel investigation into the vortex dynamics of flow around a near-wall rectangular cylinder based on direct numerical simulation at $Re=1000$, marking the first in-depth exploration of these phenomena. By varying aspect ratios ($L/D = 5$, $10$, $15$) and gap ratios ($G/D = 0.1$, $0.3$, $0.9$), the study reveals the vortex dynamics influenced by the near-wall effect, considering the incoming laminar boundary layer flow. Both $L/D$ and $G/D$ significantly influence vortex dynamics, leading to behaviours not observed in previous bluff body flows. As $G/D$ increases, the streamwise scale of the upper leading edge (ULE) recirculation grows, delaying flow reattachment. At smaller $G/D$, lower leading edge (LLE) recirculation is suppressed, with upper Kelvin–Helmholtz vortices merging to form the ULE vortex, followed by instability, differing from conventional flow dynamics. Larger $G/D$ promotes the formation of an LLE shear layer. An intriguing finding at $L/D = 5$ and $G/D = 0.1$ is the backward flow of fluid from the downstream region to the upper side of the cylinder. At $G/D = 0.3$, double-trailing-edge vortices emerge for larger $L/D$, with two distinct flow behaviours associated with two interactions between gap flow and wall recirculation. These interactions lead to different multiple flow separations. For $G/D = 0.9$, the secondary vortex (SV) from the plate wall induces the formation of a tertiary vortex from the lower side of the cylinder. Double-SVs are observed at $L/D = 5$. Frequency locking is observed in most cases, but is suppressed at $L/D = 10$ and $G/D = 0.9$, where competing shedding modes lead to two distinct evolutions of the SV.

Bilinguals may choose to speak a language either at their own will or in response to an external demand, but the underlying neural mechanisms in the two contexts is poorly understood. In the present study, Chinese–English bilinguals named pairs of pictures in three conditions: during forced-switch, the naming language altered between pictures 1 and 2. During non-switch, the naming language used was the same. During free-naming, either the same or different languages were used at participants' own will. While behavioural switching costs were observed during free-naming and forced-switching, neuroimaging results showed that forced language selection (i.e., forced-switch and non-switch) is associated with left-lateralized frontal activations, which have been implicated in inhibitory control. Free language selection (i.e., free-naming), however, was associated with fronto-parietal activations, which have been implicated in self-initiated behaviours. These findings offer new insights into the neural differentiation of language control in forced and free language selection contexts.

The numerical investigation focuses on the flow patterns around a rectangular cylinder with three aspect ratios ($L/D=5$, $10$, $15$) at a Reynolds number of $1000$. The study delves into the dynamics of vortices, their associated frequencies, the evolution of the boundary layer and the decay of the wake. Kelvin–Helmholtz (KH) vortices originate from the leading edge (LE) shear layer and transform into hairpin vortices. Specifically, at $L/D=5$, three KH vortices merge into a single LE vortex. However, at $L/D=10$ and $15$, two KH vortices combine to form a LE vortex, with the rapid formation of hairpin vortex packets. A fractional harmonic arises due to feedback from the split LE shear layer moving upstream, triggering interaction with the reverse flow. Trailing edge (TE) vortices shed, creating a Kármán-like street in the wake. The intensity of wake oscillation at $L/D=5$ surpasses that in the other two cases. Boundary layer transition occurs after the saturation of disturbance energy for $L/D=10$ and $15$, but not for $L/D=5$. The low-frequency disturbances are selected to generate streaks inside the boundary layer. The TE vortex shedding induces the formation of a favourable pressure gradient, accelerating the flow and fostering boundary layer relaminarization. The self-similarity of the velocity defect is observed in all three wakes, accompanied by the decay of disturbance energy. Importantly, the decrease in the shedding frequency of LE (TE) vortices significantly contributes to the overall decay of disturbance energy. This comprehensive exploration provides insights into complex flow phenomena and their underlying dynamics.

Rotation and orientation of non-spherical particles in a fluid flow depend on the hydrodynamic torque they experience. However, little is known about the effect of the fluid inertial torque on the dynamics of tiny inertial spheroids in turbulent channel flows, as only Jeffery torque has been considered in previous studies by point-particle direct numerical simulations. In this study, we investigate the rotation and orientation of tiny spheroids with both fluid inertial torque and Jeffery torque in a turbulent channel flow. By comparing with the case in the absence of fluid inertial torque, we find that the rotational and orientational dynamics of spheroids is significantly affected by the fluid inertial torque when the Stokes number, which is non-dimensionalized by fluid viscous time scale, is larger than the critical value $St_c\approx 2$, indicating that the fluid inertial torque is non-negligible for most particle cases considered in earlier studies. In contrast to the earlier findings considering only Jeffery torque (Challabotla et al., J. Fluid Mech., vol. 776, 2015, p. R2), we find that prolate (oblate) spheroids with a large Stokes number tend to tumble (spin) in the streamwise–wall-normal plane in a thinner region near the wall due to the presence of the fluid inertial torque. Approaching the channel centre, the flow shear gradually vanishes, but the velocity difference between local fluid and particles is still pronounced and increasing as particle inertia grows. As a result, in the core region, fluid inertial torque is dominant and drives the particles to align with its broad side normal to the streamwise direction rather than a random orientation observed in earlier studies without fluid inertial torque. Meanwhile, the presence of fluid inertial torque enhances the tumbling rates of spheroids in the core region. In addition, the effect of fluid inertial force on the dynamics of spheroids is also examined in this study, but the results indicate the effect of fluid inertial force is weak. Our findings imply the importance of fluid inertial torque in modelling the dynamics of inertial non-spherical particles in turbulent channel flows.

Multilayer dielectric gratings (MLDGs) are crucial for pulse compression in picosecond–petawatt laser systems. Bulged nodular defects, embedded in coating stacks during multilayer deposition, influence the lithographic process and performance of the final MLDG products. In this study, the integration of nanosecond laser conditioning (NLC) into different manufacturing stages of MLDGs was proposed for the first time on multilayer dielectric films (MLDFs) and final grating products to improve laser-induced damage performance. The results suggest that the remaining nodular ejection pits introduced by the two protocols exhibit a high nanosecond laser damage resistance, which remains stable when the irradiated laser fluence is more than twice the nanosecond-laser-induced damage threshold (nanosecond-LIDT) of the unconditioned MLDGs. Furthermore, the picosecond-LIDT of the nodular ejection pit conditioned on the MLDFs was approximately 40% higher than that of the nodular defects, and the loss of the grating structure surrounding the nodular defects was avoided. Therefore, NLC is an effective strategy for improving the laser damage resistance of MLDGs.

Multilayer dielectric gratings typically remove multiple-grating pillars after picosecond laser irradiation; however, the dynamic formation process of the removal is still unclear. In this study, the damage morphologies of multilayer dielectric gratings induced by an 8.6-ps laser pulse were closely examined. The damage included the removal of a single grating pillar and consecutive adjacent grating pillars and did not involve the destruction of the internal high-reflection mirror structure. Comparative analysis of the two damage morphological characteristics indicated the removal of adjacent pillars was related to an impact process caused by the eruption of localized materials from the left-hand pillar, exerting impact pressure on its adjacent pillars and eventually resulting in multiple pillar removal. A finite-element strain model was used to calculate the stress distribution of the grating after impact. According to the electric field distribution, the eruptive pressure of the dielectric materials after ionization was also simulated. The results suggest that the eruptive pressure resulted in a stress concentration at the root of the adjacent pillar that was sufficient to cause damage, corresponding to the experimental removal of the adjacent pillar from the root. This study provides further understanding of the laser-induced damage behavior of grating pillars and some insights into reducing the undesirable damage process for practical applications.

Given a graph $H$ and a positive integer $n$, the Turán number $\mathrm{ex}(n,H)$ is the maximum number of edges in an $n$-vertex graph that does not contain $H$ as a subgraph. A real number $r\in (1,2)$ is called a Turán exponent if there exists a bipartite graph $H$ such that $\mathrm{ex}(n,H)=\Theta (n^r)$. A long-standing conjecture of Erdős and Simonovits states that $1+\frac{p}{q}$ is a Turán exponent for all positive integers $p$ and $q$ with $q\gt p$.

In this paper, we show that $1+\frac{p}{q}$ is a Turán exponent for all positive integers $p$ and $q$ with $q \gt p^{2}$. Our result also addresses a conjecture of Janzer [18].

The present study evaluated effects of dietary supplementation with tryptophan (Trp) on muscle growth, protein synthesis and antioxidant capacity in hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂. Fish were fed six different diets containing 2·6 (control), 3·1, 3·7, 4·2, 4·7 and 5·6 g Trp/kg diet for 56 d, respectively. Results showed that dietary Trp significantly (1) improved muscle protein content, fibre density and frequency of fibre diameter; (2) up-regulated the mRNA levels of PCNA, myf5, MyoD1, MyoG, MRF4, IGF-I, IGF-II, IGF-IR, PIK3Ca, TOR, 4EBP1 and S6K1; (3) increased phosphorylation levels of AKT, TOR and S6K1; (4) decreased contents of MDA and PC, and increased activities of CAT, GST, GR, ASA and AHR; (5) up-regulated mRNA levels of CuZnSOD, CAT, GST, GPx, GCLC and Nrf2, and decreased Keap1 mRNA level; (6) increased nuclear Nrf2 protein level and the intranuclear antioxidant response element-binding ability, and reduced Keap1 protein level. These results indicated that dietary Trp improved muscle growth, protein synthesis as well as antioxidant capacity, which might be partly related to myogenic regulatory factors, IGF/PIK3Ca/AKT/TOR and Keap1/Nrf2 signalling pathways. Finally, based on the quadratic regression analysis of muscle protein and MDA contents, the optimal Trp requirements of hybrid catfish (21·82–39·64 g) were estimated to be 3·94 and 3·93 g Trp/kg diet (9·57 and 9·54 g/kg of dietary protein), respectively.

The South Qinling block, a segment of the Yangtze craton involved in the Qinling–Dabie orogen, is critical for understanding the tectonic evolution of eastern China. However, the tectonic setting of the South Qinling block and the northern margin of the Yangtze block during middle Neoproterozoic time has long been the subject of debate, with two distinctly different models (continental rift or volcanic arc) proposed. Here, a comprehensive study of zircon U–Pb geochronology and geochemistry has been carried out on the Chengwan granitic pluton from the Suizao terrane in the South Qinling block. The granites are monzogranite and syenogranite in lithology, and are mainly composed of potash feldspar, quartz, plagioclase and biotite. This suite has long been regarded as a Palaeozoic magmatic pluton, but zircon U–Pb ages of 809 ± 9 Ma and 816 ± 4 Ma are obtained in this study. The granites are metaluminous to strongly peraluminous with high alkali contents, and exhibit highly fractionated features, including high SiO2, low Zr/Hf ratios, rare earth element tetrad effects and enrichment of K and Rb. They show Hf–Nd isotopic decoupling, which may be genetically related to their petrogenetic process. Based on the geochemical features and the positive εHf(t) values of the zircons, it is indicated that the granites may have been derived from partial melting of juvenile tonalitic rocks by biotite breakdown under fluid-absent conditions. The Chengwan granite geochemically belongs to the A2-subtype granites, suggesting that it might have formed in a post-orogenic tectonic setting. The highly fractionated A-type granite in this study may represent extensional collapse shortly after the collisional events in the South Qinling block, and thus indicate a tectonic regime switch, from compression to extension, as early as middle Neoproterozoic time. Integrating our new data with documented magmatic, metamorphic and sedimentary events during middle Neoproterozoic time in the region may support a continental rift model, and argues against arc models.

The dependence of fishbone cycle on energetic particle intensity has been investigated in EAST low-magnetic-shear plasmas. It is observed that the fishbone mode growth rate, saturation amplitude as well as fishbone cycle frequency clearly increase with increasing neutral beam injection (NBI) power. Moreover, enhanced electron density and temperature perturbations as well as energetic particle loss were observed with greater injected NBI power. Simulation results using M3D-K code show that as the NBI power increases, the resonant frequency and the energy of the resonant particles become higher, and the saturation amplitude of the mode also changes, due to the non-perturbative energetic particle contribution. The relationship between the calculated energetic particle pressure ratio and fishbone cycle frequency is obtained as ${f_{\textrm{FC}}} = 2.2{(1000{\beta _{\textrm{ep,calc}}} - 0.1)^{5.9 \pm 0.5}}$. Results consistent with the experimental observations have been achieved based on a predator–prey model.

Having enterprises engaged in environmentally friendly behavior is an important part of reducing negative environmental impacts. This study makes a quantitative analysis against the backdrop of China's transitional economic system. The results show that politically-connected enterprises significantly reduce environmental expenditure, but this only holds for state-owned enterprises; private enterprises with political connections spend significantly more. Analysis of the efficiency of environmental expenditure indicates that, for private enterprises, environmental spending is used as a way to maintain political connections, with rent-seeking as the likely motivation. Politically-connected private enterprises have not reduced their emissions to the same extent as state-owned enterprises, despite increased expenditure. Given the scale of environmental degradation in China during a period of massive economic and social upheaval, the results of this analysis provide a quantitative case for policy change: governments should shift focus to the results that environmental spending produces.