Fluid State Research Articles

Genesis of a new type of mangan skarn associated with peraluminous granitoids in Greece

Two world-first examples of mangan oxide skarns were investigated in this study, namely the Panorama skarn of Drama and the Thapsana skarn of Paros Island, in the Rhodope and Attico-Cycladic Massifs, respectively. Transitional calcic-to-mangan exoskarn at Panorama is exposed in the garnet-epidote zone (Grt-Ep), proximal to the Panorama (micro-)granite. In Paros Island, mangan skarn is related to rhodonite (Rdn ± Ves), johannsenite-spessartine (Jhn-Sps) and spessartine-cummingtonite (Sps-Cum) zones, adjacent to marbles and/or gneisses and the Thapsana leucogranite. A two-stage manganese-oxide assemblage is present in the Thapsana skarn and comprises jacobsite, hausmannite, braunite with minor magnetite (stage I) followed by hollandite, cryptomelane and pyrite (stage II) with gangue rhodochrosite, calcite, and ankerite.Multiple isotopic evidence (i.e., δ18O, δD, δ44Ca, δ26Mg, 87Sr/86Sr, U/Pb) support the granitic source of the Mn-rich metasomatic fluids in both case studies. The Thapsana mangan skarn formed at a pressure of ∼110 MPa and a temperature range of ∼305° to 565 °C, from initially acidic (pH = 3.5), saline (up to ∼48.0 wt% NaCl equivalent), Mn chloride-bearing, skarn-forming fluids with elevated log[αMn2+/(αH+)2] and log[αMn3+/(αH+)3]. Fluid inclusions results obtained from the Jhn-Sps zone suggest phase separation of the metasomatic fluids at ∼480 °C and ∼120 MPa and ∼400 °C and ∼100 MPa. Thermodynamic modeling suggests that the manganoan skarn assemblages formed due to simple cooling and fluid-rock interaction, increase in pH and changes in the redox state of the metasomatic fluids in concert with successive deposition of Mn2+ and Mn3+ assemblages. This led to a paragenesis that comprises early anhydrous manganoan silicates, followed by more complex assemblages dominated by hydrous manganoan silicates and Mn3+ oxides.In this study we propose a metallogenic model in which mangan skarns are formed proximally to their parental leucogranites, primarily from anatectic reworking of crustal Mn-rich sources (e.g., gneisses and marbles) that delivered peraluminous melts with increased primary endowments in manganese. Exsolution of chloride magmatic fluids atypically enriched in incompatible manganese, deposited manganoan silicates and oxides with declining temperature in the skarn environment. However, in situ reworking of manganese upon fluid-rock interaction during skarnification cannot be discounted as an additional contributing source for manganese. The results of this study encourage us to propose the establishment of a new mangan-oxide mineralized skarn class as a distinct candidate for skarn mineralization.

COMPOSITION AND PHYSICO-CHEMICAL PROPERTIES OF PROTEINS IN FETAL WATER IN COMPLICATED PREGNANCY

Relevance. The physiological course of prenatal ontogenesis largely depends on the state of the amniotic fluid, which largely provides the fetus with the substances necessary for its development. Among the complications of pregnancy, premature birth leads to especially serious consequences. In this regard, the elucidation of the mechanisms for unleashing labor activity before the term is important. The most informative for achieving these goals are proteins that perform numerous functions in the regulation of cellular metabolism. Purpose of the study. To study the composition and properties of amniotic fluid proteins and the significance of their changes in predicting preterm birth. Material and methods. The study included 29 healthy women with uncomplicated pregnancy and delivery at term (control group) and 35 women who developed labor activity at 34-37 weeks (main group). In amniotic fluid taken at 16-18 weeks (by transabdominal amniocentesis), the spectrum of proteins and a number of their physicochemical properties were determined using electrophoresis, chromatography, spectrophotometry and densitom-etry methods. Results. It has been established that the development of preterm labor occurs against the background of modification of protein-protein interactions and complexing of proteins with non-protein compounds. Conclusions. The revealed imbalance of the protein composition may be an important link in the chain of functional and molecular disorders leading to preterm birth.

Unsteady Pressure-Driven Electrokinetic Slip Flow and Heat Transfer of Power-Law Fluid through a Microannulus

To guarantee the transporting efficiency of microdevices associated with fluid transportation, mixing, or separation and to promote the heat transfer performance of heat exchangers in microelectronics, the hydrodynamic behaviors at unsteady and steady states, as well as the thermal characteristics at the steady state in a pressure-driven electrokinetic slip flow of power-law fluid in a microannulus are studied. To present a more reliable prediction, the slip phenomenon at walls and nonlinear rheology of liquid are incorporated. The modified Cauchy momentum equation applicable to all time scales and energy equations, are analytically solved in the limiting case of a Newtonian fluid and numerically solved for power-law fluids. The transient velocity profile, time evolution of flow rate, temperature profile, and heat transfer rate are computed at different flow behavior indices, electrokinetic width, slip lengths, and Brinkman numbers, thereby, the coupling effect of nonlinear rheology, slip hydrodynamics, and annular geometry on flow and thermal behaviors is explored. The unsteady flow takes a longer time to achieve the steady state for shear thinning fluids or greater slip lengths. The flow behavior index and slip length play a significant role in the flow rate and heat transfer performance. The relevant discussion can serve as a theoretical guide for the operation and thermal management of annular geometry-related flow actuation systems.

The Important Role of Membrane Fluidity on the Lytic Mechanism of the α-Pore-Forming Toxin Sticholysin I.

Actinoporins have emerged as archetypal α-pore-forming toxins (PFTs) that promote the formation of pores in membranes upon oligomerization and insertion of an α-helix pore-forming domain in the bilayer. These proteins have been used as active components of immunotoxins, therefore, understanding their lytic mechanism is crucial for developing this and other applications. However, the mechanism of how the biophysical properties of the membrane modulate the properties of pores generated by actinoporins remains unclear. Here we studied the effect of membrane fluidity on the permeabilizing activity of sticholysin I (St I), a toxin that belongs to the actinoporins family of α-PFTs. To modulate membrane fluidity we used vesicles made of an equimolar mixture of phosphatidylcholine (PC) and egg sphingomyelin (eggSM), in which PC contained fatty acids of different acyl chain lengths and degrees of unsaturation. Our detailed single-vesicle analysis revealed that when membrane fluidity is high, most of the vesicles are partially permeabilized in a graded manner. In contrast, more rigid membranes can be either completely permeabilized or not, indicating an all-or-none mechanism. Altogether, our results reveal that St I pores can be heterogeneous in size and stability, and that these properties depend on the fluid state of the lipid bilayer. We propose that membrane fluidity at different regions of cellular membranes is a key factor to modulate the activity of the actinoporins, which has implications for the design of different therapeutic strategies based on their lytic action.

Pore-scale simulation of gas displacement after water flooding using three-phase lattice Boltzmann method

Water flooding is a commonly used technique to improve oil recovery, although the amount of oil left in reservoirs after the procedure is still significant. Gas displacement after water flooding is an effective way to recover residual oil, but the occurrence state and flow principles of multiphase fluid after gas injection are still ambiguous. Therefore, the gas displacement process after water flooding should be studied on the pore scale to provide a basis for formulating a reasonable gas injection program. Most of the current pore-scale studies focus on two-phase flow, while simulations that account for the influence of oil-gas miscibility and injected water are seldom reported. In this work, the multi-component multi-phase Shan-Chen lattice Boltzmann model is used to simulate the gas displacement after water flooding in a porous medium, and the effects of injected water, viscosity ratio, pore structure, and miscibility are analyzed. It is established that the injected water will cause gas flow path variations and lead to premature gas channeling. Under the impact of capillary pressure, the water retained in the porous medium during the water flooding stage further imbibes into the tiny pores during gas injection and displaces the remaining oil. When miscibility is considered, the oil-gas interface disappears, eliminating the influence of the capillary effect on the fluid flow and enabling the recovery of remaining oil at the corner. This study sheds light on the gas displacement mechanisms after water flooding from the pore-scale perspective and provides a potential avenue for improving oil recovery. Cited as: Wang, S., Chen, L., Feng, Q., Chen, L., Fang, C., Cui, R. Pore-scale simulation of gas displacement after water flooding using three-phase lattice Boltzmann method. Capillarity, 2023, 6(2): 19-30. https://doi.org/10.46690/capi.2023.02.01

Analytical accurate expressions for radial distribution function and equation of state of hard sphere fluid based on the Percus-Yevick exact solution and a new unifying closure

ABSTRACT New accurate analytic expressions for the radial distribution function and equation of state of hard sphere fluid are obtained by use of its analytic solution from Percus-Yevick closure and by a new unifying closure of the Ornstein-Zernike integral equation. This will be possible by linearisation of the closure to get a set of one-parameter structural functions incorporating both Percus-Yevick and Hyper-Netted Chain closures. This will enable us to deliver very general expressions for the structural functions and equation of state for a potential and fluid. For the most important case of hard sphere fluid the method can be complemented with its known virial coefficients to get accurate analytical expressions for its radial distribution function and equation of state. The expressions are then successfully compared with those of computer simulations for hard sphere fluid at all densities with great accuracy.

Data-Driven Modeling of General Fluid Density Under Subcritical and Supercritical Conditions

Advanced propulsion and power-generation systems often operate under extreme conditions, where thermophysical properties of the working fluids undergo complex variations in a wide range of fluid states, where empirical cubic equations of state could yield substantial errors in density prediction. The present work develops data-driven models for accurate density estimation of general fluids across all thermodynamic regimes. The model starts with the cubic equation of state, whose alpha function is calibrated in a data-driven manner with statistical correction accounting for inherent correlations among training data samples. The developed models are examined for the representative pure substances in aerospace propulsion systems, including oxygen, nitrogen, carbon dioxide, and hydrocarbon fuels. Results show that the model with pressure and temperature as input variables provides consistently superior accuracy over wide ranges of temperatures and pressures, especially in the compressed-liquid region, where the Peng–Robinson equation of state significantly underperforms. The corresponding absolute average relative deviation for the studied substances is below 0.65% at different pressures, compared to 7.16% by the Peng–Robinson equation of state. The model is also extended to examine the density calculations of the selected binary and ternary mixtures, and the consistent result is obtained. The data-driven approach can be adopted to evaluate other thermodynamic properties of fluids and fluid mixtures and characteristics of vapor–liquid equilibrium, and further incorporated into large-scale multiphysics simulations where nonideal gas behavior occurs in the future.

ГЕОДИНАМИКА И ИСТОРИЯ ФОРМИРОВАНИЯ ОКРАИННЫХ МОРЕЙ ЗАПАДНОЙ ЧАСТИ ТИХОГО ОКЕАНА КАК ВИХРЕВЫХ СТРУКТУР

In the tectonic structure of the Earth, formed by rotational processes, a stable regmatic network (tectonic framework) and structures of the central type (ring, vortex, etc.) are of the main importance. Lithosphere plates are global vortex systems arisen as a result of the tectonic flow of masses in the state of a viscous fluid. Eddy structures are tectonic complexes in which the results of vertical and horizontal tectonic movements combination are captured and can be recorded by direct geological observations. In the Western Pacific Ocean, it is noteworthy a series of structures in the form of a system of marginal seas representing the Western Pacific continent-ocean transition zone. The tectonic evolution of the West Pacific region is the formation of lithosphere eddies series in the continent-ocean junction zone. It is associated with the Earth mantle and upper shells (tectonospheres) energy interaction, due to the unstable regime of the planet’s rotational dynamics. Of particular interest are the global shear zones and eddies of the lithosphere formed as a result of horizontal and vertical tectonic movements combination. It is shown that: 1) all tectonic dislocations contain both horizontal and vertical components of the movement velocity, the former dominating in the structure formation of the region; 2) their interaction outcome is vortex and other nonlinear deformations of the lithosphere, which constitute the main type of structural elements of the region; 3) they are often accompanied by the tectonosphere magmatic activation in the form of convective movements and / or plumes “floating”; 4) the Western Pacific marginal-sea depressions are the funnels of convective cells, which formed lithosphere eddies under the conditions of a shift in the interacting lithosphere plates velocities.

Analyzing the Prebiotic Potential of Glucosamine for Targeting the Gut Microbiome Health

Recognizing the composition and modulation of the microbiome, a viable therapeutic tool for multi-targeted therapy is a new strategy that has recently been explored. Glucosamine (GS) is being studied for its prebiotic potential in addition to being the most abundant and naturally occurring amino monosaccharide. The current study focuses on glucosamine’s prebiotic potential by assessing the stability of various GS concentrations (1% - 5%) in the gastrointestinal tract (GIT) and its ability to be fermented by the gut microbiota. The results showed that GS stimulated the most growth in L. acidophilus even after a longer incubation time than B. bifidum and L. acidophilus growth was concentration-dependent, with maximum growth at 3% with a simultaneous decrease in pH (5.6 - 1.7). The decrease in GS concentration with time also represented the growth of bacterial species, demonstrating the species’ utilization of GS. Furthermore, at 3%, GS also represented the prebiotic index of 1.9. In addition, the concentration of GS in various simulated GIT fluids was estimated in both fast and fed conditions to examine GS stability at various levels in the gut. The results showed that GS remained unaffected and non-digestible in all of the simulated GIT fluids (salivary, gastric, intestinal, and colonic), but there was a slight decrease in GS concentration (2.8%) in the fasted state of gastric fluid due to low pH levels (1.6). As a result, the findings are conclusive and suggest that GS possesses prebiotic properties.

Моделирование кинетики отверждения композиционного материала в условиях открытого космоса при высоких скоростях испарения молекул

The paper proposes a mathematical model necessary for computational modeling of the features of the formation of mechanical properties during the transition of an epoxy resin from a viscous liquid to solid state during curing. We consider a problem in which the transition to a deformable state occurs under conditions close to those of outer space. An important role is played by the vacuum near the surface of the material and the high temperature resulting from the heating of the material under the influence of solar radiation. Computational modeling was carried out up to the moment of the transitionof the medium from the state of a viscous fluid to that of a deformable body. Theoret-ical calculations are compared with experimental data. Within the proposed model, the formation of the material structure at the molecular level is studied and the viscosity of the medium is calculated. The material is inhomogeneous. The presence of vacuum near the boundary of the material leads to diffusion processes. The low-mass components present in the material begin to leave the material into the surrounding vacuum. The proposed model makes it possible to trace, in time and by volume of the material, the transformation of the initial low-mass components into deformable fragments formed from them and having a larger mass. The model uses parameters that have a specific physical meaning. Information about them was obtained from the analysis of available experimental data. The experiments were carried out under laboratory vacuum conditions. The temperature in the vac-uum cabinet varied from 20 to 80 °C. Numerical modeling of the technological process was carried out using the finite element method. The material was presented in the form of a semi-infinite plate. One boundary of the plate was considered to be in contact with vacuum. Through it, the low-mass components escaped into the surrounding space. The boundary conditions were derived from the assumption that the evaporation of these components only occurs when the value of the kinetic en-ergy of diffusing molecules exceeds the amount of work necessary to overcome the energy barrier. The opposite side of the plate was considered impermeable to the material components.

Linear Rayleigh-Taylor instability for compressible viscoelastic fluids

<abstract><p>In this paper, we consider the linear Rayleigh-Taylor instability of an equilibrium state of 3D gravity-driven compressible viscoelastic fluid with the elasticity coefficient $ \kappa $ is less than a critical number $ \kappa_{c} $ in a moving horizontal periodic domain. We first construct the maximal growing mode solutions to the linearized equations by studying a family of modified variational problems, and then we prove an estimate for arbitrary solutions to the linearized equations.</p></abstract>

Finite-time blowup for the 2-D viscous primitive equations of ocean and atmosphere dynamic

The atmosphere and ocean primitive equation, which are consist of fluid equations, thermodynamic equations and state equation, play a important role for numerical weather precdiction.In an earlier work we have shown the finite-time blowup for the 3-D primitive equations of oceanic and atmospheric dynamics without viscosity by using the method of self-similar solutions.In this paper we show that for certain class of initial data, the corresponding smooth solutions of the 2-D viscous primitive equations of oceanic and atmospheric dynamics blow up in finite time.Specifically, we consider the 2-D viscous primitive equations of oceanic and atmospheric dynamics in a finite area subject to y-direction and periodic boundary conditions subject to x-direction.To overcome the viscous term, we assume the pressure function $ p(x, , y, t) $ be a concave function and reduce the 2-D primitive equations into new equations on the line $ x = 0 $ with initial and boundary conditions; and then prove that the corresponding smooth solutions of the reduced system develop singularities in finite time.

Collective behavior of passive and active circle swimming particle mixtures.

We present a numerical study on a binary mixture of passive and circle swimming, self-propelling particles which interact via the Lennard-Jones (LJ) potential in two dimensions. Using Brownian Dynamics (BD) simulations, we present state diagrams using the control parameters such as attraction strength, angular velocity, self-propulsion velocity and composition. In a symmetric mixture, the system undergoes a transition from a mixed gel to a rotating passive cluster state and finally to a homogeneous fluid state as translational activity increases. The formation of the rotating cluster of passive particles surrounded by active and passive monomers is attributed to the combined effect of composition, activity and strength of attraction of the active particles. Different phases are characterized using radial distribution functions, bond order parameters, cluster fraction and probability distribution of local volume fractions. The present study addresses comprehensively the intricate role of activity, angular velocity, inter-particle interaction and compositional variation on the phase behavior. The predictions presented in the study can be experimentally realized in synthetic colloidal swimmers and motile bacterial suspensions.

Towards freeform manufacturing of ultra-low expansion glass optics

Ultra-Low-Expansion glass (ULE®) has become an important technological enabler of advanced imaging for astronomy and for extreme-UV lithography. A major limitation though, is that ULE® cannot be poured from the fluid state unlike ZERODUR® which renders costly to produce large and/or complex shapes from it. Beside mirrors, optical components are rarely made of ULE® despite it sharing many properties of pure fused silica glass. Here we explore how femtosecond laser processing combined with laser induced reflow can be used to structure ULE® glass with the goal of producing miniature optical components. To fulfil optical roughness requirements, we adopt a strategy based on first producing elementary shapes, such as cubes or cylinders, that we further topologically transform into sphere, ellipsoids or curved surfaces, using a laser-reflow process. The structural modification of the glass matrix induced by the reflow were investigated using Raman spectroscopy. Our result points to a densification of the glass but no apparent sign of crystallization or devitrification. Furthermore, to understand whether the thermo-mechanical properties were affected or not, the thermal expansion coefficient was estimated using a dilatometry technic based on a pseudo-bimorph micro-cantilevers in a temperature-controlled chamber.

Анализ причин нестабилизированного положения газопровода на пересечениях с водными преградами

This paper analyzes the possibility of changing the position of the gas pipeline section at the stage of operation due to the transition to the fluid state of the ground environment surrounding the pipeline and due to the formation of a layer of ice around the pipe, which has a negative temperature. The article presents the results of the analysis, which show that when the ground environment surrounding the pipeline is fluid and an ice layer is formed around the pipe with a negative temperature, the ejection force may increase and the gas pipeline section may move upwards. The longitudinal compressive force due to internal pressure and changes in pipe wall temperatureduring construction and operation of the underwater crossing increases the amount of upward movement of the pipe due to the pushing force. The stable position of the Bovanenkovo - Ukhta pipeline at intersectionswith water obstacles with a width of more than 190 m is ensured by increasing the volume of actual loading by 23 %.

의료계약

This paper reviewed the legal nature of medical contracts and the legislative method of medical contracts by reviewing the problems arising in the process of establishing, implementing, and terminating medical contracts in relation to delegation contracts under civil law.
 In general, non-typical contracts can be divided into ①completely newly created, ②similar to a typical contract, but they are deformed beyond acceptance as a typical contract, and ③the specificity of the contract needs to be discussed.
 Delegation contracts and medical contracts have a common purpose of handling affairs, but there are differences in essential aspects between delegation provisions under the Civil Act for the purpose of handling property affairs and medical contracts accompanied by invasion of human life or body.
 Therefore, the norms of delegation contracts are rarely actually applied to medical contracts, or there are cases where there is partial intervention in public law, but there are cases where they have theoretical continuity.
 However, in the essential elements of both contracts, medical contracts have their own characteristics independent of delegation contracts. Medical contracts are not completely newly created or modified to the point that they cannot be included in a typical contract. Therefore, it should be said that it is a type that needs to be discussed in the delegation contract. In other words, it should be said that delegation contracts and medical contracts have a relative relationship between general types and special types, abstract types and specific types, or basic types and subtypes.
 Even if medical contracts are subordinate to delegation contracts, the difference between delegation contracts and medical contracts should be seen as larger than non-typical contracts (franchise contracts, etc.) in the form of different office processes theoretically and practically.
 Since medical contracts are basically based on the rules of human life and body invasion, they should be considered to have a significant difference from the civil law's delegation regulations governing property management. If so, it should be seen that there is a characteristic that cannot be solved by a delegation contract under civil law and a new type of typical contract under civil law.
 Civil law discussions on the obligations of doctors and patients arising from medical contracts are still in a fluid state. The Civil Code established the basic framework of contracts between individuals.
 It is not appropriate to incorporate medical contracts with strong public legal elements within these civil codes. As for the legislative form of medical contracts, it is considered reasonable to enact civil special law specializing in medical contracts.

Molecular Dynamics and Chain Length of Edible Oil Using Low-Field Nuclear Magnetic Resonance

Nuclear magnetic resonance (NMR) techniques are widely used to identify pure substances and probe protein dynamics. Edible oil is a complex mixture composed of hydrocarbons, which have a wide range of molecular size distribution. In this research, low-field NMR (LF-NMR) relaxation characteristic data from various sample oils were analyzed. We also suggest a new method for predicting the size of edible oil molecules using LF-NMR relaxation time. According to the relative molecular mass, the carbon chain length and the transverse relaxation time of different sample oils, combined with oil viscosity and other factors, the relationship between carbon chain length and transverse relaxation time rate was analyzed. Various oils and fats in the mixed fluid were displayed, reflecting the composition information of different oils. We further studied the correlation between the rotation correlation time and the molecular information of oil molecules. The molecular composition of the resulting fluid determines its properties, such as viscosity and phase behavior. The results show that low-field NMR can obtain information on the composition, macromolecular aggregation and molecular dynamics of complex fluids. The measurements of grease in the free-fluid state show that the relaxation time can reflect the intrinsic properties of the fluid. It is shown that the composition characteristics and states of complex fluids can be measured using low-field nuclear magnetic resonance.

Application of SCF-LTDP technology for a-Si:H film defective passivation in X-ray PIN-based photosensor

The quality and stability of X-ray flat panel detectors and fingerprint identifiers are crucial requirements for high-resolution applications and to ensure successful manufacture and commercially applicability. To achieve higher resolutions, the areas of the photodiodes must be reduced, which results in an increase in the leakage current owing to sidewall defects caused by the photodiodes. This study introduces a supercritical fluid low-temperature defect passivation (SCF-LTDP) treatment to repair the dangling bonds of amorphous silicon (a-Si) PIN-diode-based photo sensors. Unlike traditional atmospheric annealing processes, the hydrogen achieves a low-temperature and high-pressure fluid state in this technique, which offers the advantages of deeper penetration, higher surface tension, and greater viscous force. This technique helps suppress the leakage current generated in the reverse bias voltage by passivating the defects under illumination. The recombination current caused by the defects is, therefore, reduced, resulting in an overall increase of the photocurrent in the X-ray photodiode. The results obtained in this study are beneficial for the development of PIN diodes for panel detector applications.

Modeling of water hammer effect during the single cavitating bubble oscillation

The paper presents the results of an analytical study of the vapor-gas bubble dynamics in cavitation processes, giving consideration to the liquid compressibility. The study is based on the concept that cavitation effects are directly related to the occurrence of hydraulic shock on the surface of an extremely compressed bubble. The purpose of this work is to study cavitation bubble dynamics accounting for the spherical water hammer effects. An equation for the bubble dynamics was obtained, which includes the coefficient of liquid adiabatic compressibility as a basic parameter that is directly related to the liquid compressibility. For this equation reduces to the classical Rayleigh-Plesset equation for incompressible liquids. The results of a computational experiment performed within the framework of the modified model are presented for which the behavior of a cavitation bubble both in compressible and in incompressible water was analyzed. Based on a detailed analysis of the results obtained, it is shown that over time .the compressed bubble is in the state of a supercritical fluid with temperature up to 2000 K and pressure of about 400 MPa. The potential energy of the compressed liquid, in the form of a powerful acoustic pulse, emitted by the bubble at the stage of its collapse, is irreversibly dissipated in the surrounding liquid.

Layer formation in a stably stratified fluid cooled from above: Towards an analog for Jupiter and other gas giants

Composition gradients in the interior of Jupiter can affect and even suppress convective motions. In some situations, a composition gradient can trigger the formation of multiple convective layers separated by sharp diffusive interfaces, preventing further mixing. This fluid state, called layered convection, has been proposed to occur in giant planets. However, it is not guaranteed that secondary convective layers can form and survive underneath a turbulent convection zone. Our simulations find that below an evolving convection zone, layer formation is difficult and the fluid always fully mixes. This may have bearing on the survival of composition gradients in Jupiter's interior.