High prevalence of long COVID symptoms has emerged as a significant public health concern. This study investigated the associations between three doses of COVID-19 vaccines and the presence of any and ≥3 types of long COVID symptoms among people with a history of SARS-CoV-2 infection in Hong Kong, China. This is a secondary analysis of a cross-sectional online survey among Hong Kong adult residents conducted between June and August 2022. This analysis was based on a sub-sample of 1,542 participants with confirmed SARS-CoV-2 infection during the fifth wave of COVID-19 outbreak in Hong Kong (December 2021 to April 2022). Among the participants, 40.9% and 16.1% self-reported having any and ≥3 types of long COVID symptoms, respectively. After adjusting for significant variables related to sociodemographic characteristics, health conditions and lifestyles, and SARS-CoV-2 infection, receiving at least three doses of COVID-19 vaccines was associated with lower odds of reporting any long COVID symptoms comparing to receiving two doses (adjusted odds ratio [AOR]: 0.69, 95% CI: 0.54, 0.87, P = .002). Three doses of inactivated and mRNA vaccines had similar protective effects against long COVID symptoms. It is important to strengthen the coverage of COVID-19 vaccination booster doses, even in the post-pandemic era.

Vapour bubbles produced by long-pulsed laser often have complex non-spherical shapes that reflect some characteristics of the laser beam. The transition between two commonly observed shapes, namely, a rounded pear-like shape and an elongated conical shape, is studied using a new computational model that combines compressible multiphase fluid dynamics with laser radiation and phase transition. Two laboratory experiments are simulated, in which a holmium:YAG or thulium fibre laser is used to generate bubbles of different shapes. In both cases, the predicted bubble nucleation and morphology agree reasonably well with the experimental observation. The full-field results of laser irradiance, temperature, velocity and pressure are analysed to explain bubble dynamics and energy transmission. It is found that due to the lasting energy input, the vapour bubble's dynamics is driven not only by advection, but also by the continued vaporisation at its surface. Vaporisation lasts less than $1~{\rm \mu}$s in the case of the pear-shaped bubble, compared with over $50~{\rm \mu}$s for the elongated bubble. It is thus hypothesised that the bubble's morphology is determined by competition. When the speed of advection is higher than that of vaporisation, the bubble tends to grow spherically. Otherwise, it elongates along the laser beam direction. To test this hypothesis, the two speeds are defined analytically using a model problem, then estimated for the experiments using simulation results. The results support the hypothesis. They also suggest that when the laser's power is fixed, a higher laser absorption coefficient and a narrower beam facilitate bubble elongation.

With the over-use of tetracycline (TC) and its ultimate accumulation in aquatic systems, the demand for TC removal from contaminated water is increasing due to its severe threat to public health. Clay minerals have attracted great attention as low-cost adsorbents for controlling water pollution. The objective of the present study was to measure the adsorption behavior and mechanisms of TC on allophane, a nanosized clay mineral with a hollow spherical structure; to highlight the advantage of the allophane nanostructure, a further objective was to compare allophane with halloysite and montmorillonite, which have nanostructures that differ from allophane. Structural features and surface physicochemical properties were characterized by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential, N2-physisorption, and acid–base titration. The adsorption data showed that TC adsorption followed the pseudo-second order and Langmuir models. The adsorption was pH dependent, as all three clay minerals performed better under neutral to weakly alkaline conditions and maintained high adsorption performance in the presence of co-existing Na+/K+/Ca2+/Mg2+ cations. Regeneration of the adsorbent was excellent, with efficiencies exceeding 75% after five recycles. By comparison, allophane always exhibited the greatest adsorption capacity, up to 796 mg g–1 at ~pH 9. The TC adsorption on allophane and halloysite was dominated by inner-sphere complexation, together with a small amount of electrostatic adsorption, while that on montmorillonite involved mainly interlayer cation exchange. The findings provide insights into the effects of nanostructures of clay minerals on their TC adsorption performance and highlight the huge potential of allophane as an efficient and inexpensive adsorbent for TC removal.

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.

In this paper, we analyse Turing instability and bifurcations in a host–parasitoid model with nonlocal effect. For a ordinary differential equation model, we provide some preliminary analysis on Hopf bifurcation. For a reaction–diffusion model with local intraspecific prey competition, we first explore the Turing instability of spatially homogeneous steady states. Next, we show that the model can undergo Hopf bifurcation and Turing–Hopf bifurcation, and find that a pair of spatially nonhomogeneous periodic solutions is stable for a (8,0)-mode Turing–Hopf bifurcation and unstable for a (3,0)-mode Turing–Hopf bifurcation. For a reaction–diffusion model with nonlocal intraspecific prey competition, we study the existence of the Hopf bifurcation, double-Hopf bifurcation, Turing bifurcation, and Turing–Hopf bifurcation successively, and find that a spatially nonhomogeneous quasi-periodic solution is unstable for a (0,1)-mode double-Hopf bifurcation. Our results indicate that the model exhibits complex pattern formations, including transient states, monostability, bistability, and tristability. Finally, numerical simulations are provided to illustrate complex dynamics and verify our theoretical results.

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.

Microporous structure in zeolite leads to diffusion limitation, which causes coke formation and is harmful to catalytic reactions. Hierarchical zeolite containing primary microporosity and secondary porosity at the meso- and macroscales has received much attention due to its enhanced mass transport. Hierarchical Y zeolites were obtained by treating NH4-Y zeolite with high-temperature calcining and acid-base leaching. The results demonstrated that the calcined zeolite showed great crystallinity after acid-base leaching. The mechanism of introduction of mesopores was demonstrated in detail. The calcination transformed framework Al to extra-framework Al and enlarged the defect by acid and alkali. The mesopores increased with the calcining temperature and holding time. The relationship between the heating rate and the removal of Al species was non-linear; a heating rate of 100°C/h exhibited good protection for the zeolite structure.

Adsorption desulfurization is a potential new method for deep desulfurization of fuel oil. The development of adsorbents with high adsorption capacity and selectivity is the core of deep adsorption desulfurization. The adsorption behavior of thiophene in MCM-41 mesoporous materials modified by various metal ions was studied in order to understand the adsorption desulfurization process of molecular sieves. The Fe-, Co-, and Zn-modified MCM-41 materials were prepared using a one-step in situ hydrothermal synthesis method. The modified MCM-41 molecular sieves maintained the mesoporous structure, and the metal ions had specific dispersion on the surface of the molecular sieves. Adsorption of thiophene on the surfaces of molecular sieves had both physical and chemical characteristics. The adsorption desulfurization performance of the modified molecular sieve was superior to that of the pure silica molecular sieve. In the simulated gasoline with sulfur content of 220 μg/g, when the amount of adsorbent used was 100 mg, the adsorptive desulfurization performance tended to be in equilibrium, and the optimum adsorption temperature was 30°C. Fe-MCM-41 and MCM-41 molecular sieves reached adsorption equilibrium after ~60 min, but the desulfurization rate of Co-MCM-41 and Zn-MCM-41 still increased slightly. The kinetic simulation results indicated that the pseudo-second-order kinetics adsorption model described well the adsorption process of thiophene on molecular sieves. The molecular sieve Fe-MCM-41 had the best desulfurization performance with an equilibrium adsorption capacity of 14.02 mg/g and the desulfurization rate was ~90%.

The laser-driven flyer plate is an important loading technology in high energy physics, shock wave physics, and explosive initiation application. How to generate a high-velocity and intact flyer plate by using the laser is a matter of concern for laser driving. In this study, the multilayer flyer plates (MFPs) of Al/Al2O3/Al and TiO2/Al/Al2O3/Al with adjustable performance were designed and fabricated by magnetron sputtering and analyzed by scanning electron microscopy (SEM), laser reflectance spectrometer, and differential thermal analysis (DTA). The effects of the structure and material on the output performance of MFPs were analyzed by photon Doppler velocimetry (PDV) and ultrahigh-speed video. The morphology results showed that the structure of MFPs had uniform and clear boundaries between side-by-side layers. The MFP velocity was controlled in the range of 4.0–6.0 km/s by adjusting the film thickness, structure, and thermite material with 43.1 J/cm2 laser ablation. Among them, the energetic flyers with the thermite ablation layer had the highest final velocity of 5.38 km/s due to the prestored energy of TiO2/Al. By appropriately increasing the thickness of Al2O3 from 0.4 μm to 0.8 μm, the complete flight of the flyer plate to 3.72 mm can be realized. In addition, TiO2/Al thermite film had characteristics of reaction heat release and lower laser reflectivity (72.13%) than the Al layer (80.55%), which explained the velocity enhancement effect of energetic flyer plates. This work provides facile strategy to enhance the output performance of MFPs, which may facilitate the practical applications of laser driving technology.

Salt solutions have complex effects on the swelling characteristics of compacted bentonite; these effects are caused by the inhibitory action of salinity and the ion-exchange reaction between the solution and bentonite. In order to characterize the swelling properties of compacted bentonite in a salt solution, swelling deformation tests were carried out for Gao-Miao-Zi (GMZ) bentonite specimens in NaCl and CaCl2 solutions. Swelling characteristics decreased with increasing salt concentration. Swelling strains in NaCl solution were larger than those in CaCl2 solution, even though the ionic concentration of 1.0 mol/L (M) NaCl solution is larger than that of 0.5 M CaCl2. According to the exchangeable cations tests, cation exchange was different for specimens immersed in different salt solutions. The swelling fractal model was used to predict the swelling strains of compacted bentonite in a concentrated salt solution. In this model, the effective stress incorporating osmotic suction was applied to take the effect of salinity into consideration, and the swelling coefficient, K, was employed to describe the swelling properties affected by the variation in exchangeable cations. In the model, fractal dimension was measured by nitrogen adsorption, and the salt solution had little effect on fractal dimension. K was estimated by the diffuse double layer (DDL) model for osmotic swelling in distilled water. Comparison of fractal model estimations with experimental data demonstrated that the new model performed well in predicting swelling characteristics affected by a salt solution.

Product graphics interchange formats (GIFs) employ this format to show the features of the product and make up for the lack of physical experience online. These GIFs have been widely applied in domains such as e-shopping and social media, aiming to interest and impress viewers. Contrary to this wide application, most designers in this domain lack expertise and produce GIFs of varied quality. Moreover, the knowledge of techniques to enhance viewers’ engagement with product GIFs is also lacking. To bridge the gap, we conducted a series of studies. First, we collected and summarized seven design factors referring to existing literature and semi-structured interviews. Then, the impacts of these design factors were revealed through an online study with 106 product GIFs among 307 participants. The results showed that visual-related factors such as color contrast and moving intensity mainly impact viewers’ interest, while content-related factors such as scenario and style matching impact viewers’ impressions. The simplicity of GIFs also impressed viewers with a quick viewing mode. Finally, we conducted a workshop and verified that these results support large-scale production of product GIFs. Our studies might support the codesign methods of product GIFs and enhance their quality in design practice.

This study presents novel findings on stochastic electron heating via a random electron cyclotron wave (ECW) in a spherical tokamak. Hard x ray measurements demonstrate the time evolution of hard x ray counts at different energy bands, consistent with predictions from the stochastic heating model. The ECW heating rate shows a positive correlation with applied power, confirming the effectiveness of stochastic heating. Remarkably, the ECW-driven plasma current remains insensitive to ECW incidence angle, consistent with model predictions. The observed stochastic heating of electrons offers potential for exploring innovative non-inductive current drive modes in spherical tokamaks. This research contributes to the understanding of plasma behaviour and motivates the development of new models for non-inductive current drive in fusion devices.

In this paper, we investigate the constrained attitude control problem of hypersonic vehicles (HVs). An improved prescribed performance dynamic surface control method is proposed based on an adaptive scaling strategy. Because of the uncertain time-varying disturbances, the controlled state may violate the constraint in the prescribed performance control (PPC) framework. An adaptive scaling strategy is introduced in the PPC method to avoid state violation. The performance function is scaled with respect to the state adaptively. Moreover, a nonlinear disturbance observer is used to compensate the sum of external and other internal disturbances of the system. The proposed method improves the system dynamic performance while ensuring the system robustness. Furthermore, the stability of the closed-loop system is proved by Lyapunov analysis. Finally, numerical simulations are implemented to verify the effectiveness of the PPC method and superiority over other methods.

Carotenoids are important bioactive substances in breast milk, the profile of which is seldom studied. This study aimed to explore the profile of carotenoids in breast milk and maternal/cord plasma of healthy mother–neonate pairs in Shanghai, China, and their correlation with dietary intake. Maternal blood, umbilical cord blood and breast milk samples from five lactation stages (colostrum, transitional milk and early-, mid- and late-term mature milk) were collected. Carotenoid levels were analysed by HPLC. Carotenoid levels in breast milk changed as lactation progressed (P < 0·001). β-Carotene was the primary carotenoid in colostrum. Lutein accounted for approximately 50 % of total carotenoids in transitional milk, mature milk and cord blood. Positive correlations were observed between five carotenoids in umbilical cord blood and maternal blood (P all < 0·001). β-Carotene levels were also correlated between maternal plasma and three stages of breast milk (r = 0·605, P < 0·001; r = 0·456, P = 0·011, r = 0·446; P = 0·013, respectively). Dietary carotenoid intakes of lactating mothers also differed across lactation stages, although no correlation with breast milk concentrations was found. These findings suggest the importance of exploring the transport mechanism of carotenoids between mothers and infants and help guide the development of formulas for Chinese infants as well as the nutritional diets of lactating mothers.

The flow past a cylinder in proximity to a plane wall is investigated numerically for small gap ratios. Three vortex dynamic processes associated with different hairpin vortex generation mechanisms are identified for the first time, and the wake-induced turbulent transition is analysed. The vortex shedding is suppressed at $G/D = 0.1$, while the spanwise vortex is generated via a Kelvin–Helmholtz instability and evolves into hairpin vortices. For $G/D= 0.3$, the upper and lower rollers alternatively shedding from the cylinder, interact with the secondary vortex. The split secondary vortex merges with the upper roller and results in a new vortex downstream, which develops into hairpin vortices. When $G/D = 0.9$, the secondary vortex interacts with the lower roller and then evolves into hairpin vortices. A tertiary vortex induced by the secondary vortex is observed, rotating in the opposite direction to the secondary vortex the wake-induced transitions share the same route. The velocity fluctuations deviate from the optimal growth theory in the pre-transitional region. In the transitional region low-frequency disturbances penetrate the sheltering edge to generate streaks where the disturbance energy declines. In the turbulent region the logarithmic layer is formed, indicating that the turbulent equilibrium is established.