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In this study, we develop unified and analytical frameworks to examine the effect of viscosity, elasticity, and viscoelasticity on the Rayleigh–Taylor instability (RTI), which underlies finger formation during prompt splashing as a droplet impacts a flat metal surface. We complement our theoretical developments with experimental validations designed to match our theoretical predictions. A new dimensionless number, R = R e / W e 3 / 4 , is introduced to characterize the evolution of the finger patterns. Three distinctive regimes are identified based on our analysis: when R ≲ 1 , the number of fingers scales with R e 2 / 3 ; for 1 ≲ R ≲ 10 , the finger count is influenced by both Re and We, a regime not extensively studied previously; and for R ≳ 10 , the count becomes insensitive to Re. We also discern a transient deceleration effect, represented by g = 16 V 0 2 / D , which prompts perturbation development due to RTI. It is noted that the constant 16 is dependent on fluid and surface physical properties. Though our theoretical predictions closely align with experimental observations, it is noteworthy that in experimental settings, g exhibits significant temporal variability. Further, our study extends to include viscoelastic effects, facilitating comparisons with recent advancements in managing finger formation in splashing scenarios. Additional experiments targeting medium R values further corroborate our theoretical model. This comprehensive analysis not only reaffirms but also enhances the understanding of splashing dynamics by integrating complex material behaviors and characteristics, thus offering a substantive benchmark for future research in the field. [ABSTRACT FROM AUTHOR]

In their study, Terrones et al. ["Rayleigh–Taylor instability at spherical interfaces between viscous fluids: The fluid/fluid interface," Phys. Fluids 32, 094105 (2020)] elucidated that investigations into the viscous Rayleigh–Taylor instability (RTI) in spherical geometry at a quiescent interface yield significant physical insights. Yet, the complexity amplifies when addressing a dynamic spherical interface pertinent to engineering and scientific inquiries. The dynamics of RTI, particularly when influenced by the Bell–Plesset effects at such interfaces, offers a rich tapestry for understanding perturbation growth. The evolution of this instability is describable by a coupled set of equations, allowing numerical resolution to trace the radius evolution and instability characteristics of a bubble akin to the implosion scenario of a fusion pellet in inertial confinement fusion scenarios. The investigation encompasses the impact of viscosity, external pressure, discrete mode, and a surface-tension-like force on the interfacial instability. In general, the oscillation of the bubble radius exhibits a decay rate that diminishes with increasing Reynolds number (Re). It is important to note that the growth of the perturbed amplitude is not only solely determined by the mechanical properties of the fluid but also by the dynamics of the interface. The low-order modal (n < 20) disturbance is dominant with relatively high Reynolds numbers. There is a specific mode corresponding the maximum in amplitude of perturbation in the linear phase, and the mode decreases as the Re decreases. The application of external pressure noticeably accelerates the bubble's oscillation and impedes its shrinkage, thereby preventing the bubble from collapsing completely. The increase in external pressure also promotes the transition from the first peak to the trough of the disturbance. At higher-order modes, the fluctuation of the disturbance curve tends to be uniform. The ultrahigh-order modes require a strong enough pressure to be excited. In addition, the smaller Weber number (We) helps to accelerate the bubble oscillation and promote the fluctuation of the disturbance amplitude, but has no significant effect on the time of the disturbance peak. These findings contribute to a deeper understanding of interfacial instabilities in the context of spherical bubbles and, especially, for the dynamics of fusion capsules in inertial confinement fusion. [ABSTRACT FROM AUTHOR]

A unified analytical approach to study the effects of elasticity, viscosity, and magnetic fields on the Richtmyer–Meshkov (RM) instability by using the impulsively accelerated model is presented. This model clarifies the discontinuity in the oscillation periods and yields the asymptotic decaying rate in elastic solids. It reveals that the complex eigenvalues produce better results compared with the numerical simulations for RM instability in viscous fluids and resolves the standing controversy between the analytical theory and numerical simulations at a vacuum/fluid interface. At last, it easily retrieves the results when the normal or tangential magnetic field is present. Those good agreements, between numerical simulations and theoretical analysis, would enable the model to be valuable in more complex situations such as in the elastic–plastic slabs with or without the presence of magnetic fields, as well as in the nonlinear regime. [ABSTRACT FROM AUTHOR]

Reservoir spaces, such as vesicles, 'secondary' amygdales, dissolution caverns and geodes, are widely developed in the Emeishan basaltic lavas in the Zhoudaping section, Leshan, west Sichuan, China. The dissolution characteristics, cementation sequences, hydrothermal activity stages, as well as fluid types, and their effects on the reservoir capacity were investigated for each stage. Macroscopically, the dissolution features present as irregular dissolution zones, which are characterised by a light red colour. Microscopically, in the dissolved zone, the cementation-filling minerals are associated with complex fill sequences, such as quartz/laumontite/chlorite–chlorite/saponite–epidote/celadonite–cryptocrystalline chlorite–laumontite/calcite/quartz. The U–Pb geochronology shows that the age of chlorite fill in amygdales is 235.3 ± 19.6 Ma; the coarse-crystalline quartz inside dissolution caverns/geodes, 124.47 ± 5.63 to 123.84 ± 5.63 Ma; and the siliceous mineral-filled amygdales, 118.34 ± 3.70 to 114.08 ± 3.76 Ma, which correspond to the early Late Triassic and the mid–late Early Cretaceous, respectively. Combined with geochemical characteristics of post-dissolution fill, the amygdales are affected by two stages of hydrothermal activity: chlorite filling of the amygdales corresponds to post-magma hydrothermal fluids during the early Late Triassic, and the siliceous mineral-fill in amygdales corresponds to deep-sourced hydrothermal fluids during the mid–late Early Cretaceous. The geodes/dissolution caverns result from a single stage of hydrothermal activity related to the mid–late Early Cretaceous deep-source low-temperature hydrothermal fluid. The Late Triassic post-magma hydrothermal fluids are generally destructive to pores, and tectonic-related dissolution of deep-sourced hydrothermal fluids has a positive effect on the formation of reservoir spaces, greatly enhancing fluid storage and flow capacities of the volcanic lavas. We recommend the multi-stage hydrothermal dissolution during Late Triassic–Early Cretaceous and faults, fractures and columnar joints be the focus of hydrocarbon exploration. The reservoir spaces developed in the Zhoudaping section, such as amygdales, dissolution caverns and geodes, were controlled by different stages and types of hydrothermal alteration. Amygdales are the product of two hydrothermal events, which correspond to post-magma hydrothermal fluids during the early Late Triassic and the deep-sourced hydrothermal fluids of the mid–late Early Cretaceous. Geodes/dissolution caverns are affected by deep-source low-temperature hydrothermal fluids in the mid–late Early Cretaceous. The multi-stage hydrothermal dissolution during the Late Triassic–Early Cretaceous and faults, fractures and columnar joints should be the focus of hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

Recent experimental and numerical results demonstrates that the interfacial motion of a liner Z-pinch during the early stage of implosion may be controlled by the coupled effects of magneto-Rayleigh–Taylor (MRT), sausage, and kink instabilities. However, previous treatments of sausage instability have not considered the mechanical properties of the liner material. In this paper, we present an analytical model that allows us to study the effects of liner viscosity and elasticity on the coupling effects of MRT and sausage instabilities, and we further assume that the wavelengths are much smaller than the liner thickness by neglecting the feedthrough effect. The dispersion relations are analyzed. It is found that viscosity suppresses short-wavelength perturbations, and longer wavelengths are needed to achieve the fastest growing mode as the viscosity grows. Elasticity also strongly suppresses short-wavelength perturbations and eventually leads to the appearance of a cutoff wavenumber beyond which the interface always remains stable. In particular, the present approach provides the basis for the development of a more general theory that would also include magnetohydrodynamic instabilities and would allow a more accurate description of liner motion. [ABSTRACT FROM AUTHOR]

A unified and analytical model is developed to study the effects of an inclined magnetic field on magneto-Rayleigh–Taylor (MRT) and magneto-Richtmyer–Meshkov (MRM) instabilities in ideal magnetohydrodynamics. Unlike either a horizontal or a vertical magnetic field is present, the decay modes possess decaying and oscillation behaviors together. The vorticity transportation is analyzed. The dispersion relations are derived, and some interesting phenomena are observed. For a small R that represents the ratio of the magnetic field strength, or equivalently, the inclination θ, the growth rate of MRT instabilities resembles the case when a vertical magnetic field is present. For a large R, the growth rate resembles to the case when a horizontal magnetic field exists. The maximum growth rate becomes strongly dependent on At instead of on R. Furthermore, analytical expression is obtained for the MRM instability by using the impulsive accelerated model. The decaying and oscillating rates of the perturbed amplitude are explicitly related to θ. For two limiting cases, with either the vertical or the horizontal magnetic field existing, our results retrieve previous one of the theoretical analyses and numerical simulations. Generally, the asymptotic amplitude becomes independent of the wave number of the initial perturbation in the MRM instability. These findings regarding magneto-hydrodynamic interfacial instabilities in an inclined magnetic field could provide physical insights for magnetically driven targets and astrophysical observations. This analytical model is easily expanded to investigate the effects of finite thickness of magnetic slab and sheared magnetic field in relevant to high-energy-density physics and to astrophysics. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Tracheal intubation under general anesthesia is more likely to aggravate the injury of the cervical spine and spinal cord. We aim to explore the effect of dexmedetomidine combined with intubating laryngeal mask airway (ILMA) on anesthesia and stress response in patients with a cervical spine injury PATIENTS AND METHODS: One hundred twenty patients were retrospectively allocated into the control group (midazolam + ILMA) and intervention group (dexmedetomidine + ILMA). Their hemodynamics at T1 (before anesthesia induction), T2 (1 minute after anesthesia induction), T3 (immediately after intubation), and T4 (1 min after successful intubation) were also compared. RESULTS: The heart rate (HR) and mean arterial pressure (MAP) of patients in the observation group were lower than those in the control group from T3 to T4 (both p = 0.000). Ramsay's score in the observation group was higher than the control group from T3 to T4 (both p= 0.000). No difference was observed in PaO2, PaCO2, and pH between the 2 groups. The level of serum cortisol (COR), plasma epinephrine (E), and norepinephrine (NE) in the observation group were lower than in the control group (p < 0.05) after induction. CONCLUSIONS: Dexmedetomidine combined with ILMA could improve the first intubation success rate and tolerance in patients with cervical spine injury by maintaining stable hemodynamics and reducing the stress response of patients. [ABSTRACT FROM AUTHOR]

The relative influence of insolation, CO2, and ice sheets on the East Asian summer monsoon (EASM) is not well understood especially at regional scale. Here a Gaussian emulator based on simulations with HadCM3 is used to quantitatively assess how astronomical forcing, CO2, and northern hemisphere ice sheets affect the variation of the summer precipitation over the last 800 ky. Our results show that in the EASM domain north of 25°N, the variation of the summer precipitation is dominated by precession, leading to strong 23‐ky cycles, while the ice sheets only modulate the effect of insolation by influencing the land‐sea pressure gradient. In the southern part, ice sheets play a more important role, generating 100‐ky cycles, through influencing the latitude of the Intertropical Convergence Zone and the Hadley cell. Obliquity and CO2 have little effect on the summer precipitation as compared to precession and ice sheets. Plain Language Summary: The East Asian summer monsoon (EASM) is a wind which carries moist air from the Indian and Pacific Oceans to East Asia, and it affects the economy and life of a large population. On astronomical time scale, its variation is controlled by insolation, CO2, and ice sheets. Here we use a Gaussian emulator based on climate simulations to assess how these factors affect the variation of the summer precipitation in East Asia. In the northern part of the EASM domain, the summer precipitation has a strong 23‐ky cycle. It is mainly controlled by precession. The effect of insolation is further modulated by ice sheets by the variations of the land‐sea pressure gradient. In the southern part, ice sheets play a vital role on the summer precipitation via its control on the location of the Intertropical Convergence Zone. Obliquity and CO2 have little effect on the precipitation. Key Points: In northern East Asia, the variation of summer precipitation is dominated by precessionIn southern East Asia, ice volume plays a more important role on the summer precipitation via its control on the location of Intertropical Convergence ZoneThe effects of obliquity and CO2 on summer precipitation are very small compared to precession and ice volume [ABSTRACT FROM AUTHOR]

Multiple experiments were performed to evaluate the ecotoxicological effect of mesotrione on soil enzymatic activity, functional diversity, and genetic microbial biodiversity. The results showed that catalase and invertase activity initially increased with higher mesotrione concentration and then declined slightly. However, urease activity experienced a 11.9-23.2% reduction in comparison to control soil. The average well-color development (AWCD) was positively affected by the mesotrione treatment, the amount of carbohydrate, amino acid, and phenolic acid increased by 1.7-2.1, 1.1-1.6, and 1.7-2.5 times, respectively, when compared with the blank treatment. However, the utilization of carboxylic and acid amine was prohibited after applying 50-100 mg kg-1 and 20-100 mg kg-1 mesotrione. Denaturing gradient gel electrophoresis (DGGE) analysis showed that the shift in the bacterial community structure for different mesotrione treatments can be mainly attributed to an increment in band intensity, while the dissimilarity in the bacterial genetic structure decreased with increasing mesotrione content in the soil. Sequencing and phylogenetic analyses showed that the four bands in the denaturing gradient gel electrophoresis results were closely related to Bacillus subterraneus, Clostridium sp., and Bacillus sp. Obtained results show that abuse of mesotrione may pose a potential risk for soil microbial functioning. [ABSTRACT FROM AUTHOR]