We studied flow organization and heat transfer properties in mixed turbulent convection within Poiseuille–Rayleigh–Bénard channels subjected to temporally modulated sinusoidal wall temperatures. Three-dimensional direct numerical simulations were performed for Rayleigh numbers in the range $10^6 \leqslant Ra \leqslant 10^8$, a Prandtl number $Pr = 0.71$ and a bulk Reynolds number $Re_b \approx 5623$. We found that high-frequency wall temperature oscillations had minimal impact on flow structures, while low-frequency oscillations induced adaptive changes, forming stable stratified layers during cooling. Proper orthogonal decomposition (POD) analysis revealed a dominant streamwise unidirectional shear flow mode. Large-scale rolls oriented in the streamwise direction appeared as higher POD modes and were significantly influenced by lower-frequency wall temperature variations. Long-time-averaged statistics showed that the Nusselt number increased with decreasing frequency by up to 96 %, while the friction coefficient varied by less than 15 %. High-frequency modulation predominantly influenced near-wall regions, enhancing convective effects, whereas low frequencies reduced these effects via stable stratified layer formation. Phase-averaged statistics showed that high-frequency modulation resulted in phase-stable streamwise velocity and temperature profiles, while low-frequency modulation caused significant variations due to weakened turbulence. Turbulent kinetic energy (TKE) profiles remained high near the wall during both heating and cooling at high frequency, but decreased during cooling at low frequencies. A TKE budget analysis revealed that during heating, TKE production was dominated by shear near the wall and by buoyancy in the bulk region; while during cooling, the production, distribution and dissipation of TKE were all nearly zero.

In this paper, we simulate the process of two-dimensional axisymmetric fluid–structure coupling of a droplet impacting on a flexible disk. The effects of dimensionless disk stiffness (K = 0.1–1000), Weber number (We = 1–500) and contact angle (θ = 130° and 60°) on the dynamics of the droplet impacting on the flexible disk are analysed. The results indicate that there are five typical impact modes for a hydrophobic surface (θ = 130°) and four typical impact modes for a hydrophilic surface (θ = 60°) within the range of considered parameters. The analysis of spreading factor reveals that a part of the energy is transferred to the substrate, which is manifested as a weakening of the droplet spreading, when the substrate deforms downwards due to the droplet impact; the squeezing of the droplet causes a tendency to flow from the centre of the droplet to the edge, which is manifested as an enhancement of the droplet spreading, when the substrate recovers from the downward deformation. The effect of the substrate flexibility on the maximum spreading factor depends on the competition of the two mechanisms above. Based on this, a modified scaling law of βmax has been proposed by introducing the effective Weber number (Wem). The analysis of impact force demonstrates that the peak of the impact force is related to the deflection of the flexible substrate which is different from that of a rigid wall; and three typical processes of impact force variation have been summarised. In addition, unlike the rigid substrate scenario, there is an energy interaction between the droplet and the flexible substrate after impact occurs, which is classified as three typical energy transformation processes.

We report a high-power ultra-narrow fiber-coupled diode laser using a Faraday anomalous dispersion optical filter (FADOF) as an external cavity element. An external cavity suitable for both the fiber-coupled package and FADOF configuration has been proposed. Using a 87Rb-based FADOF as the frequency-selective element, we realized a 103 W continuous laser output with a uniform circular beam. The center wavelength was precisely locked at the D2 line of the Rb resonance, and the bandwidth was narrowed from 1.8 nm (free-running, full width at half maximum (FWHM)) to 0.013 nm (6.9 GHz, FWHM). The side mode suppression ratio reached 31 dB. Such diode lasers with precise wavelength and high spectral brightness have critical applications in many fields, such as high-energy gas laser pumping, spin-exchange optical pumping, Raman spectroscopy and nonlinear optics.

Text readability assessment aims to automatically evaluate the degree of reading difficulty of a given text for a specific group of readers. Most of the previous studies considered it as a classification task and explored a wide range of linguistic features to express the readability of a text from different aspects, such as semantic-based and syntactic-based features. Intuitively, when the external form of a text becomes more complex, individuals will experience more reading difficulties. Based on this motivation, our research attempts to separate the textual external form from the text and investigate its efficiency in determining readability. Specifically, in this paper, we introduce a new concept, namely textual form complexity, to provide a novel insight into text readability. The main idea is that the readability of a text can be measured by the degree to which it is challenging for readers to overcome the distractions of external textual form and obtain the text’s core semantics. To this end, we propose a set of textual form features to express the complexity of the outer form of a text and characterize its readability. Findings show that the proposed external textual form features can be used as effective evaluation indexes to indicate the readability of text. It brings a new perspective to the existing research and provides a new complement to the existing rich features.

We studied the transport and deposition behaviour of point particles in Rayleigh–Bénard convection cells subjected to Couette-type wall shear. Direct numerical simulations (DNSs) are performed for Rayleigh number ($Ra$) in the range $10^{7} \leq Ra \leq ~10^9$ with a fixed Prandtl number $Pr = 0.71$, while the wall-shear Reynolds number ($Re_w$) is in the range $0 \leq Re_w \leq ~12\,000$. With the increase of $Re_w$, the large-scale rolls expanded horizontally, evolving into zonal flow in two-dimensional simulations or streamwise-oriented rolls in three-dimensional simulations. We observed that, for particles with a small Stokes number ($St$), they either circulated within the large-scale rolls when buoyancy dominated or drifted near the walls when shear dominated. For medium $St$ particles, pronounced spatial inhomogeneity and preferential concentration were observed regardless of the prevailing flow state. For large $St$ particles, the turbulent flow structure had a minor influence on the particles’ motion; although clustering still occurred, wall shear had a negligible influence compared with that for medium $St$ particles. We then presented the settling curves to quantify the particle deposition ratio on the walls. Our DNS results aligned well with previous theoretical predictions, which state that small $St$ particles settle with an exponential deposition ratio and large $St$ particles settle with a linear deposition ratio. For medium $St$ particles, where complex particle–turbulence interaction emerges, we developed a new model describing the settling process with an initial linear stage followed by a nonlinear stage. Unknown parameters in our model can be determined either by fitting the settling curves or using empirical relations. Compared with DNS results, our model also accurately predicts the average residence time across a wide range of $St$ for various $Re_w$.

The egg parasitoid Anastatus japonicus is a key natural enemy in the biological control of various agricultural and forestry pests. It is particularly used against the brown marmorated stink bug Halyomorpha halys and the emerging defoliator pest Caligula japonica in East Asia. It has been proved that the eggs of Antheraea pernyi can be used as a factitious host for the mass production of A. japonicus. This study systematically documented the parasitic behaviour and developmental morphology exhibited by A. japonicus on the eggs of A. pernyi. The parasitic behaviour of A. japonicus encompassed ten steps including searching, antennation, locating, digging, probing, detecting, oviposition, host-feeding, grooming, and resting. Oviposition, in particular, was observed to occur in three stages, with the parasitoids releasing eggs during the second stage when the body remained relatively static. Among all the steps of parasitic behaviour, probing accounted for the longest time, constituting 33.1% of the whole time. It was followed by digging (19.3%), oviposition (18.5%), antennation (9.6%), detecting (7.4%), and the remaining steps, each occupying less than 5.0% of the total event time. The pre-emergence of adult A. japonicus involves four stages: egg (0 to 2nd day), larva (3rd to 9th day), pre-pupa (10th to 13th day), pupa (14th to 22nd day), and subsequent development into an adult. Typically, it takes 25.60 ± 0.30 days to develop from an egg to an adult at 25℃. This information increases the understanding of the biology of A. japonicus and may provide a reference for optimising reproductive devices.

The assessment of seed quality and physiological potential is essential in seed production and crop breeding. In the process of rapid detection of seed viability using tetrazolium (TZ) staining, it is necessary to spend a lot of labour and material resources to explore the pretreatment and staining methods of hard and solid seeds with physical barriers. This study explores the TZ staining methods of six hard seeds (Tilia miqueliana, Tilia henryana, Sassafras tzumu, Prunus subhirtella, Prunus sibirica, and Juglans mandshurica) and summarizes the TZ staining conditions required for hard seeds by combining the difference in fat content between seeds and the kinship between species, thus providing a rapid viability test method for the protection of germplasm resources of endangered plants and the optimization of seed bank construction. The TZ staining of six species of hard seeds requires a staining temperature above 35 °C and a TZ solution concentration higher than 1%. Endospermic seeds require shorter staining times than exalbuminous seeds. The higher the fat content of the seeds, the lower the required incubation temperature and TZ concentration for staining, and the longer the staining time. And the closer the relationship between the two species, the more similar their staining conditions become. The TZ staining method of similar species can be predicted according to the genetic distance between the phylogenetic trees, and the viability of new species can be detected quickly.

The familiar process of bubbles generated via breaking waves in the ocean is foundational to many natural and industrial applications. In this process, large pockets of entrained gas are successively fragmented by the ambient turbulence into smaller and smaller bubbles. The key question is how long it takes for the bubbles to reach terminal sizes for a given system. Despite decades of effort, the reported breakup time from multiple experiments differs significantly. Here, to reconcile those results, rather than focusing on one scale, we measure multiple time scales associated with the process through a unique experiment that resolves bubbles’ local deformation and curvature. The results emphasize that the scale separation among various time scales is controlled by the Weber number, similar to how the Reynolds number determines the scale separation in single-phase turbulence, but shows a distinct transition at a critical Weber number.

The laboratory generation and diagnosis of uniform near-critical-density (NCD) plasmas play critical roles in various studies and applications, such as fusion science, high energy density physics, astrophysics as well as relativistic electron beam generation. Here we successfully generated the quasistatic NCD plasma sample by heating a low-density tri-cellulose acetate (TCA) foam with the high-power-laser-driven hohlraum radiation. The temperature of the hohlraum is determined to be 20 eV by analyzing the spectra obtained with the transmission grating spectrometer. The single-order diffraction grating was employed to eliminate the high-order disturbance. The temperature of the heated foam is determined to be T = 16.8 ± 1.1 eV by analyzing the high-resolution spectra obtained with a flat-field grating spectrometer. The electron density of the heated foam is about $N_e=4.0\pm 0.3\times {10}^{20}{\text{cm}}^{-3}$ under the reasonable assumption of constant mass density.

In preparation for an experiment with a laser-generated intense proton beam at the Laser Fusion Research Center at Mianyang to investigate the 11B(p,α)2α reaction, we performed a measurement at very low proton energy between 140 keV and 172 keV using the high-voltage platform at the Institute of Modern Physics, Lanzhou. The aim of the experiment was to test the ability to use CR-39 track detectors for cross-section measurements and to remeasure the cross-section of this reaction close to the first resonance using the thick target approach. We obtained the cross-section σ = 45.6 ± 12.5 mb near 156 keV. Our result confirms the feasibility of CR-39 type track detector for nuclear reaction measurement also in low-energy regions.

Diode-pumped rare gas lasers are potential candidates for high-energy and high-beam quality laser systems. Currently, most investigations are focused on metastable Ar lasers. The Kr system has the unique advantages of higher quantum efficiency and lower discharge requirements for comparison. In this paper, a diode-pumped metastable Kr laser was demonstrated for the first time. Using a repetitively pulsed discharge at a Kr/He pressure of up to approximately 1500 Torr, metastable Kr atoms of more than 1013 cm–3 were generated. Under diode pumping, the laser realized a dual-wavelength output with an average output power of approximately 100 mW and an optical conversion efficiency of approximately 10% with respect to the absorbed pump power. A kinetics study involving population distribution and evolution was conducted to analyze the laser performance.

According to the public data collected from the Health Commission of Gansu Province, China, regarding the COVID-19 pandemic during the summer epidemic cycle in 2022, the epidemiological analysis showed that the pandemic spread stability and the symptom rate (the number of confirmed cases divided by the sum of the number of asymptomatic cases and the number of confirmed cases) of COVID-19 were different among 3 main epidemic regions, Lanzhou, Linxia, and Gannan; both the symptom rate and the daily instantaneous symptom rate (daily number of confirmed cases divided by the sum of daily number of asymptomatic cases and daily number of confirmed cases) in Lanzhou were substantially higher than those in Linxia and Gannan. The difference in the food sources due to the high difference of the population ethnic composition in the 3 regions was probably the main driver for the difference of the symptom rates among the 3 regions. This work provides potential values for prevention and control of COVID-19 in different regions.

We studied the flow organization and heat transfer properties in two-dimensional and three-dimensional Rayleigh–Bénard cells that are imposed with different types of wall shear. The external wall shear is added with the motivation of manipulating flow mode to control heat transfer efficiency. We imposed three types of wall shear that may facilitate the single-roll, the horizontally stacked double-roll, and the vertically stacked double-roll flow modes, respectively. Direct numerical simulations are performed for fixed Rayleigh number $Ra = 10^{8}$ and fixed Prandtl number $Pr = 5.3$, while the wall-shear Reynolds number ($Re_{w}$) is in the range $60 \leqslant Re_{w} \leqslant 6000$. Generally, we found enhanced heat transfer efficiency and global flow strength with the increase of $Re_{w}$. However, even with the same magnitude of global flow strength, the heat transfer efficiency varies significantly when the cells are under different types of wall shear. An interesting finding is that by increasing the wall-shear strength, the thermal turbulence is relaminarized, and more surprisingly, the heat transfer efficiency in the laminar state is higher than that in the turbulent state. We found that the enhanced heat transfer efficiency at the laminar regime is due to the formation of more stable and stronger convection channels. We propose that the origin of thermal turbulence laminarization is the reduced amount of thermal plumes. Because plumes are mainly responsible for turbulent kinetic energy production, when the detached plumes are swept away by the wall shear, the reduced number of plumes leads to weaker turbulent kinetic energy production. We also quantify the efficiency of facilitating heat transport via external shearing, and find that for larger $Re_{w}$, the enhanced heat transfer efficiency comes at a price of a larger expenditure of mechanical energy.

The G protein-coupled receptors (GPCR) sensing nutritional signals (amino acids, fatty acids, glucose, etc.) are not fully understood. In this research, we used transcriptome sequencing to analyse differentially expressed genes (DEG) in mouse mammary gland tissues at puberty, lactation and involution stages, in which eight GPCR were selected out and verified by qRT-PCR assay. It was further identified the role of GPR110-mediating nutrients including palmitic acid (PA) and methionine (Met) to improve milk synthesis using mouse mammary epithelial cell line HC11. PA but not Met affected GPR110 expression in a dose-dependent manner. GPR110 knockdown decreased milk protein and fat synthesis and cell proliferation and blocked the stimulation of PA on mechanistic target of rapamycin (mTOR) phosphorylation and sterol-regulatory element binding protein 1c (SREBP-1c) expression. In summary, these experimental results disclose DEG related to lactation and reveal that GPR110 mediates PA to activate the mTOR and SREBP-1c pathways to promote milk protein and fat synthesis.

Vitamin D (VD) plays a vital role in various physiological processes in addition to its classic functions on maintaining the balance of Ca and P metabolism. However, there still are gaps to understand in depth the issues on the precise requirement, metabolic processes and physiological functions of VD in fish. In this study, we investigated the effects of VD on the growth, intestinal health, host immunity and metabolism in turbot (Scophthalmus maximus L.), one important commercial carnivorous fish in aquaculture, through the supplementation of different doses of dietary VD3 (0, 200, 400, 800 and 1600 μg VD3/kg diet). According to our results, the optimal VD3 level in the feed for turbot growth was estimated to be around 400 μg/kg, whereas VD3 deficiency or overdose in diets induced the intestinal inflammation, lowered the diversity of gut microbiota and impaired the host resistance to bacterial infection in turbot. Moreover, the level of 1α,25(OH)2D3, the active metabolite of VD3, reached a peak value in the turbot serum in the 400 μg group, although the concentrations of Ca and phosphate in the turbot were stable in all groups. Finally, the deficiency of dietary VD3 disturbed the nutritional metabolism in turbot, especially the metabolism of lipids and glucose. In conclusion, this study evaluated the optimal dose of dietary VD3 for turbot and provided the evidence that VD has a significant impact on intestinal health, host immunity and nutritional metabolism in fish, which deepened our understanding on the physiological functions and metabolism of VD3 in fish.