A macroscale floating object moving downwards will encounter an increasing buoyancy force exerted by the liquid. However, considering the surface tension and the deformed meniscus, we find an exotic floating object of specific shape that withstands a constant total force exerted by the liquid when it moves vertically and slowly. This constant total force consists of the surface tension force and the hydrostatic pressure force, from which a model to determine the shape of the exotic floating object is proposed. Results show that there exist three types of exotic floating objects in both the two-dimensional symmetric and axisymmetric cases, dependent on their concavity and convexity. To ensure that the menisci around the exotic floating objects can be sustained in practice, the stabilities of these menisci are checked. Apart from the meniscus stabilities (of liquid surfaces), the floating stabilities (of solid objects) are also studied. It is demonstrated that the exotic floating object remains in a critical state of floating stabilities no matter where this object locates vertically, from which a new method to predict the floating stabilities for general floating objects of arbitrary shape is put forward, based on the contact angle and the geometrical parameters at the contact point. With the new method, the floating stabilities can be predicted conveniently, without performing an extra force analysis.

Despite the widespread occurrence of pendant drops in nature, there is still a lack of combined studies on their dynamic and static stability. This study focuses on the dynamic and static stability of elongated drops with either a free or pinned contact line on a plane. We first examine static stability for both axisymmetric and non-axisymmetric perturbations subject to volume or pressure constraints. The stability limits for volume and pressure disturbances (axisymmetric) correspond to the maximum volume and pressure of the drops, respectively. Drops with free contact lines are marginally stable to non-axisymmetric perturbations because of their horizontal translational invariance, whereas pinned drops are stable. The linear dynamic stability is then investigated numerically through a boundary element model, restricted to volume disturbances. Results show that when the stability limit is reached, the first zonal mode has a zero frequency, suggesting that the thresholds for static and dynamic stability are essentially equivalent. Furthermore, natural frequencies experience sharp changes as the stability limit is approached. Another zero frequency mode associated with the horizontal motion of the centre of mass is also revealed by the numerical results, reflecting the horizontal translational invariance of drops with free contact lines. Finally, the frequency spectrum modified by gravity is explored, resulting in the identification of five gravity-induced frequency shift patterns. The frequency shifts break the spectral degeneracy for hemispherical drops with free contact lines, leading to various spectral orderings according to polar and azimuthal wavenumbers.

Natural oscillations of sessile drops with a free or pinned contact line in different gravity environments are studied based on a linear inviscid irrotational theory. The inviscid Navier–Stokes equations and boundary conditions are reduced to a functional eigenvalue problem by the normal-mode decomposition. We develop a boundary element method model to numerically solve the eigenvalue problem for predicting the natural frequencies. Emphasis is placed on the frequency shifts of modes due to gravity for a wide range of contact angles $\alpha$ and Bond numbers $Bo$. Three types of $\alpha$–$Bo$ diagrams reflecting how gravity shifts the frequency are identified. Specifically, the frequency of zonal modes shifts downwards (upwards) when $\alpha$ is smaller (larger) than a critical value, while the frequencies of most sectoral modes are shifted downwards regardless of $\alpha$. As a result, gravity can transform the lowest mode from a zonal mode to a sectoral mode. The spectral degeneracy of hemispherical drops inherited from the Rayleigh–Lamb spectrum is also broken by gravity. However, we discover that gravity has no effect on the mode associated with the horizontal motion of the centre of mass, whose frequency is always zero regardless of $\alpha$ and $Bo$. This implies that the ‘walking’ drop instability reported in previous literature does not exist.

A horizontal cylinder with a concave cross-section partially submerged in a liquid at a given position may permit multiple menisci around itself. The number and stabilities of the menisci are analysed, and how the menisci change during the processes of gradually hoisting and lowering the cylinder is explained by bifurcation theory. The restoring force on the concave cylinder and the rebounding potential energy (defined as the work done by the restoring force during the whole hoisting process to represent the potential rebounding capacity of a cylinder on water) are also investigated. The results show that, when the radius of the concave arc is smaller than the critical value, the concave cylinder at a given position permits multiple possible menisci. The equilibria form fold bifurcations with the position of the cylinder as the bifurcation parameter, and two successive fold bifurcations can form a one-fold hysteresis loop. The force–distance curve representing the relation between the restoring force and the position of the cylinder also has corresponding hysteresis loops, where the restoring force will jump (i.e. change discontinuously) at the bifurcation points. In contrast to a convex cylinder, a concave cylinder can have different values of the restoring force at the same height because of multiple menisci, and the values depend on whether it is hoisted or lowered. Under the condition of a fixed cross-sectional area, the optimal cross-sectional shape is determined when the maximum rebounding potential energy is reached, and it is close to the shape with the critical concave arc angle for the existence of multiple possible menisci. The cross-sections with concave parts are preferable to circular, laterally planed and corner-concave cross-sections. This paper provides an effective method of enhancing the restoring force and potential rebounding height of a robotic water strider insect or particles on the surface of water.

Drawing from the theory of territorial behavior, this article predicts the explanatory role of silence behavior in the relationship between knowledge hiding and hider's innovative behavior in Chinese organizations, and the potential of Zhongyong thinking in mitigating the detrimental effect of knowledge hiding. Results derived from a time-lagged and multi-source survey support our hypotheses. Specifically, knowledge hiding is negatively associated with the innovative behavior of the hider. Silence behavior mediates the relationship between knowledge hiding and innovative behavior. Meanwhile, Zhongyong thinking moderates the positive relationship between knowledge hiding and silence behavior, as well as the indirect relationship between knowledge hiding and innovative behavior through silence behavior. Theoretical and practical implications are discussed based on these findings.

At present, the study on autonomous unmanned ground vehicle navigation in an unstructured environment is still facing great challenges and is of great significance in scenarios where search and rescue robots, planetary exploration robots, and agricultural robots are needed. In this paper, we proposed an autonomous navigation method for unstructured environments based on terrain constraints. Efficient path search and trajectory optimization on octree map are proposed to generate trajectories, which can effectively avoid various obstacles in off-road environments, such as dynamic obstacles and negative obstacles, to reach the specified destination. We have conducted empirical experiments in both simulated and real environments, and the results show that our approach achieved superior performance in dynamic obstacle avoidance tasks and mapless navigation tasks compared to the traditional 2-dimensional or 2.5-dimensional navigation methods.

Whereas the existing literature on the relationship between parental behavior and family business succession mainly focuses on parental behavior in the business domain, we highlight the importance of parental behavior in the family domain. Integrating attachment theory, the family business succession literature, and person-job fit literature, our study proposes a theoretical framework hypothesizing that general self-efficacy and perceived person-job fit mediate the association between perceived parental care (an underrepresented family-domain-specific parental behavior) and next-generation family members’ succession intentions. This framework is tested by data from two surveys and further verified by qualitative interviews of next-generation family members. Multivariate analysis results suggest that next-generation family members’ general self-efficacy and perceived person-job fit played a sequential-mediating role in the relationship between perceived parental care and next-generation family members’ succession intentions. Our interviews not only confirm these results but also reveal new insights, particularly into the specific Chinese context in the study of family business succession.

Schistosomiasis has been subjected to extensive control efforts in the People's Republic of China (China) which aims to eliminate the disease by 2030. We describe baseline results of a longitudinal cohort study undertaken in the Dongting and Poyang lakes areas of central China designed to determine the prevalence of Schistosoma japonicum in humans, animals (goats and bovines) and Oncomelania snails utilizing molecular diagnostics procedures. Data from the Chinese National Schistosomiasis Control Programme (CNSCP) were compared with the molecular results obtained.

Sixteen villages from Hunan and Jiangxi provinces were surveyed; animals were only found in Hunan. The prevalence of schistosomiasis in humans was 1.8% in Jiangxi and 8.0% in Hunan determined by real-time polymerase chain reaction (PCR), while 18.3% of animals were positive by digital droplet PCR. The CNSCP data indicated that all villages harboured S. japonicum-infected individuals, detected serologically by indirect haemagglutination assay (IHA), but very few, if any, of these were subsequently positive by Kato-Katz (KK).

Based on the outcome of the IHA and KK results, the CNSCP incorporates targeted human praziquantel chemotherapy but this approach can miss some infections as evidenced by the results reported here. Sensitive molecular diagnostics can play a key role in the elimination of schistosomiasis in China and inform control measures allowing for a more systematic approach to treatment.

The Middle Miocene Climatic Optimum is known for abrupt events during the global cooling trend of the past 20 Ma. Its identification in the Tibetan Plateau can help explain the cause of the critical Middle Miocene climate transition in Central Asia. In this study, fine-grained mixed sediments widely distributed in the Miocene Qaidam Lake in the northern Tibetan Plateau were used as a sensitive indicator for palaeoclimate. Their geochemical characteristics were investigated, together with an analysis of 2600 m long successive gamma-ray logging data from the whole JS2 drillcore, to understand the mid-Miocene climate transition in the Tibetan Plateau. By comparing the gamma-ray curve of the mixed sediments with global temperature, the Middle Miocene Climatic Optimum event can be easily identified. Further, the detailed petrological features and geochemical data of lacustrine fine-grained mixed sediments from a 400 m drillcore show oxidizing, high-sedimentation rate and brackish-saline water conditions in a semi-arid climate during the Middle Miocene period, demonstrating a dryer climate in the Qaidam Basin than in the monsoon-sensitive regions in Central Asia. These fine-grained mixed sediments have recorded climate drying before 15.3 Ma that represents a climatic transition within the Middle Miocene Climatic Optimum; increasing carbonate-rich mixed sediments, decreasing algal limestone layers and decreasing lacustrine organic matter are indicators of this transition. Regional tectonic events include the retreat of the Paratethys from Central Asia at ∼15 Ma and the synchronous tectonic reorganization of the Altyn-Tagh fault system and the northeastern Tibetan Plateau. We find that global climate change is the primary factor affecting the overall characteristics and changes of the Neogene climate in the Qaidam Basin, including the occurrence of the Middle Miocene Climatic Optimum and the cooling and drying tendency, while the regional events are a secondary factor.

A miniaturized high-isolation quadplexer with wide upper-stopband based on open and short stub-loaded multimode-resonator is proposed in this paper. Based on the theory of multimode-resonator and stepped impedance resonator (SIR), the compact quadplexer is designed by using multimode-resonator and SIR. In order to further miniaturize the size of the circuit, the multimode resonator is employed as the common resonator to replace the common matching network of the quadplexer and the SIRs are curved. Equivalent topology circuit is given to analyze and design the quadplexer. Detailed analyses are given according to the equivalent circuits. The proposed compact quadplexer working at central frequencies of 1.8, 2.4, 2.8, and 3.5 GHz with over 40 dB isolation is finally simulated, fabricated, and measured. The measured results agree well with the simulated ones. The total size of the fabricated quadplexer is 0.36 λg × 0.42 λg.

The general exotic capillary tube is a non-uniform capillary tube which permits an entire continuum of equilibrium menisci if applying a pressure $p=-\unicode[STIX]{x1D700}z$ at the tube inlet. The shapes of general exotic capillary tubes under positive and negative loads are determined mathematically. Lowering the pressure at the tube inlet slightly from the value $p=-\unicode[STIX]{x1D700}z$ causes the tube to completely drain out, while raising the pressure slightly forces the tube to fill up, which implies that the general exotic capillary tube is sensitive to pressure. The general exotic capillary tube is also related to meniscus stability. It is found that the boundary parameters $\unicode[STIX]{x1D712}_{1}$ of general exotic cylinders with arbitrary contact angle are equal to the critical values $\unicode[STIX]{x1D712}_{1}^{\ast }$ for determining the meniscus stability. Then, a convenient alternative to solving the Jacobi equation for determining $\unicode[STIX]{x1D712}_{1}^{\ast }$ is proposed based on the ‘exotic’ property.

A capillary surface in or around exotic cylinders cannot locate itself, since the configurations of the exotic cylinders with a variable radius permit an entire continuum of equilibrium menisci, all of which have the same potential energy. The ‘exotic’ property indicates that all the menisci have the smallest eigenvalues $\unicode[STIX]{x1D706}_{1}=0$ for the corresponding Sturm–Liouville problems without a volume constraint for stability analysis. Three types of exotic cylinders are addressed and the Sturm–Liouville problems with $\unicode[STIX]{x1D706}=0$ for stability analysis are solved numerically. Notably, the two-dimensional cases can be solved analytically. In the method of Slobozhanin & Alexander (Phys. Fluids, vol. 15, 2003, pp. 3532–3545), the stability of the meniscus is determined by comparing the boundary parameter $\unicode[STIX]{x1D712}_{1}$ and the critical value $\unicode[STIX]{x1D712}_{1}^{\ast }$, which is derived directly from the solution of the Sturm–Liouville problem with $\unicode[STIX]{x1D706}=0$. Results validate that the exotic cylinders have the boundary parameters $\unicode[STIX]{x1D712}_{1}=\unicode[STIX]{x1D712}_{1}^{\ast }$. Motivated by this observation, a new way to determine the critical value $\unicode[STIX]{x1D712}_{1}^{\ast }$ under pressure disturbances for stability analysis is proposed without solving the Sturm–Liouville problem with $\unicode[STIX]{x1D706}=0$.

Highly dense zirconia dental ceramic coatings were fabricated by aqueous electrophoretic deposition (EPD) and subsequently sintered between 1250 and 1450 °C. Microstructural examination revealed that aqueous EPDZrO2 coatings possessed a tetragonal phase structure and the grain size increased with increasing sintering temperature. Nanoindentation study proved that the aqueous EPDZrO2 coating also had excellent mechanical properties. The effect of different applied loads on hardness and elastic modulus of the 1350 °C-sintered sample at room temperature was investigated by the method of progressive multicycle measurement nanoindentation. The simulative experiment proved that hardness of aqueous EPDZrO2 exhibited reverse indentation size effect (ISE) behavior and then displayed the normal ISE response. The analysis indicates that the reverse ISE is attributed to the relaxation of surface stresses resulting from indentation cracks at small loads and normal ISE is caused by geometrically necessary dislocations. The tetragonal–monoclinic stress-induced phase transformation during nanoindentation is the primary cause of dental zirconia failures.

Fluorescence and phase transitions of a new Mg-Al-Eu ternary layered double hydroxide (LDH) and their dependence on thermal treatment were studied for the first time. Phase transitions occurred as the temperature increased from 400 to 1100°C. The process of phase transition is discussed in detail. The emissions of Eu3+ ions described by the 5D0–7FJ transition (J = 1,2,3,4), and especially for the 5D0–7FJ transition (J = 1,2) varied markedly with phase transformations from LDH, MgO, to mixtures of MgO and MgAl2O4. Moreover,strong emissions of Eu3+ ions are present in these new host materials. These results indicate that Mg-Al-Eu ternary LDH may be a potential candidate for materials applied in fluorescent devices.

A model for calculating the force profile and the moment profile of a floating body in two dimensions with an arbitrary cross-section is proposed. Three types of cross-sections with different contact angles and densities are calculated by using the model to determine the vertical and rotational equilibria and their stabilities. Results show that the model can be applied to convex floating bodies with finitely many sharp edges. The study is then extended to investigate the surface tension effects on the vertical and rotational stabilities by varying the following parameters: the radii of curvature of the solid surface at the contact lines and the size of floating body. In general, the smaller the radii of curvature the better the vertical and rotational stabilities. However, for the contact angle $\unicode[STIX]{x1D703}=0$ (or $\unicode[STIX]{x1D703}=\unicode[STIX]{x03C0}$) the radii of curvature have no effect on the vertical stability of the floating body. By varying the size of the floating body, it is found that the vertical and rotational stabilities of mesoscale floating bodies vary continuously between the stabilities of the macroscale and microscale floating bodies with other parameters remaining unchanged.

Previous studies have demonstrated adverse mental health effects of Pb exposure. The purpose of this study is to investigate the relationship between consumption of preserved egg (PE), a high-Pb-containing food and depressive symptoms among adults in China. A sample of 25 213 adults (mean age 41·4 (sd 11·8) years; males, 53·9 %) in Tianjin, China, was studied in a cross-sectional analysis. Dietary intake including PE was assessed using a valid self-administered FFQ. Depressive symptoms were assessed using the Self-Rating Depression Scale (SDS). The association was estimated by OR using logistic regression models adjusted for multiple confounders. The prevalence of elevated depressive symptoms was 6·6 % (SDS≥50). Compared with the least frequent PE consumption (<once/week), multivariable adjusted OR for elevated depressive symptoms were 1·52 (95 % CI 1·28, 1·81), 2·24 (95 % CI 1·76, 2·81) and 3·31 (95 % CI 2·52, 4·30) for consumption of once, 2–3 times and ≥4 times/week, respectively (Pfor trend<0·0001), indicating a clear dose–response relationship. The results suggested that higher consumption of PE was strongly associated with depressive symptoms among adults in China. These findings underscore the need to consider dietary Pb exposure as a risk factor for psychological distress.