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In this work, we propose a linear machine learning force matching approach that can directly extract pair atomic interactions from ab initio calculations in amorphous structures. The local feature representation is specifically chosen to make the linear weights a force field as a force/potential function of the atom pair distance. Consequently, this set of functions is the closest representation of the ab initio forces, given the two-body approximation and finite scanning in the configurational space. We validate this approach in amorphous silica. Potentials in the new force field (consisting of tabulated Si–Si, Si–O, and O–O potentials) are significantly different than existing potentials that are commonly used for silica, even though all of them produce the tetrahedral network structure and roughly similar glass properties. This suggests that the commonly used classical force fields do not offer fundamentally accurate representations of the atomic interaction in silica. The new force field furthermore produces a lower glass transition temperature (Tg ∼ 1800 K) and a positive liquid thermal expansion coefficient, suggesting the extraordinarily high Tg and negative liquid thermal expansion of simulated silica could be artifacts of previously developed classical potentials. Overall, the proposed approach provides a fundamental yet intuitive way to evaluate two-body potentials against ab initio calculations, thereby offering an efficient way to guide the development of classical force fields. [ABSTRACT FROM AUTHOR]

Due to the significant pollution caused by the current extraction technology for deep coalbed methane (CBM), we propose the application of anhydrous cracking technology—liquid nitrogen cyclic freeze–thaw technology—to crack deep coal seams to achieve the release and extraction of coal bed methane. The self-made system for applying confining pressure is employed to simulate the deep coal seam in coal sample testing. Subsequently, the effect of joint structure with different angles of coal surface and bedding on the liquid nitrogen cyclic freeze–thaw process is evaluated. The investigation study identifies the damage patterns of the coal sample against the sole factor and coupling effect of confining pressure and joint angle. The findings reveal a clear impact of the cyclic freeze–thaw of liquid nitrogen on the expansion of deep coal seams. The application of appropriate inclined joints, combined with confining pressure, significantly minimizes the crushing time of coal samples, with the maximum expansion rate occurring at joints with a bedding angle of 45°±5°. This study provides vital theoretical support for the green and efficient exploitation of deep CBM. Practical Applications: The results of this study indicate that the waterless hydraulic fracturing technology—liquid nitrogen cyclic freeze–thaw technology—is highly suitable for coalbed methane extraction in deep, low-permeability coal seams, leading to increased gas recovery. The deeper the coal seam, the more pronounced the effects. Moreover, this technology does not cause environmental pollution. It specifically targets the pores, fractures, and joint structures within the coal, preserving the overall framework of the coal and preventing tunnel instability, thereby enhancing coal mining safety. Additionally, under the influence of liquid nitrogen cyclic freeze–thaw, joints at different angles exhibit varying rates of expansion. Joints extending at a 45° angle to the coal's bedding planes show the most rapid expansion, indicating that this orientation stores the maximum amount of coalbed methane postliquid nitrogen freeze–thaw. This pattern can be scientifically applied in the actual engineering design of extraction wells. The experimental results can provide a theoretical basis for guiding the on-site application of deep coal seam permeability enhancement and green coalbed methane extraction technology, thereby reducing environmental pollution. [ABSTRACT FROM AUTHOR]

The structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond‐breaking strategy is demonstrated for synthesizing ultrathin metal–organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs' structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials. [ABSTRACT FROM AUTHOR]

The structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond‐breaking strategy is demonstrated for synthesizing ultrathin metal–organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs' structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials. [ABSTRACT FROM AUTHOR]

As a new type of proton conductor, metal–organic frameworks (MOFs) have attracted much attention because of their superior properties over conventional materials, such as the modifiability of framework, reversibility of coordination bond, high specific surface area, and porosity. It is predicted that the proton conductivities of MOFs can be improved by hole expansion and ionic liquid introduction. In this work, HKUST‐1 and LP‐HKUST‐1 were prepared, which were filled with different proportions of N‐methylimidazole triflate (MIM‐CF3SO3) to prepare composite materials MIM‐CF3SO3@HKUST‐1‐100% and MIM‐CF3SO3@LP‐HKUST‐1‐x (x = 25%, 50%, 75% and 100%). A total of seven kinds of materials were synthesized. The proton conductivities of all the materials at 75% RH were tested from 303 to 353 K. In this environment, MIM‐CF3SO3@LP‐HKUST‐1‐100% shows excellent proton conductivity (σ = 0.341 S·cm−1 at 353 K, 75% relatively humidity [RH]), being 7060 times that of HKUST‐1, and reaches the peak value of MOF family in recent years. Then, the conductivities of parts of the materials were tested in extreme environments, such as in high‐humidity environment (303–353 K, 100% RH), high‐temperature environment (373–423 K, N2 atmosphere), and low‐temperature environment (253–283 K, 75% RH). The results show that under all conditions above, the proton conductivity of MIM‐CF3SO3@LP‐HKUST‐1‐100% is the best, up to 0.341 S·cm−1 at 353 K and 75% RH, 0.179 S·cm−1 at 353 K and 100% RH, 1.31 × 10−3 S·cm−1 at 283 K and 75% RH, and 2.31 × 10−4 S·cm−1 at 423 K and N2 atmosphere, indicating that proton conductivity of HKUST‐1 is improved by hole expansion and ionic liquid introduction. Finally, the stability test showed that MIM‐CF3SO3@LP‐HKUST‐1‐100% was stable in all environments above. Moreover, the conductive mechanism of HKUST‐1 before and after introduction of ionic liquids was also discussed, providing a theoretical basis for the enhancement of proton conductivities of MOFs using ionic liquid introduction and hole expansion. [ABSTRACT FROM AUTHOR]

Expanding emulsions with liquid CO2 facilitates the creation of aerosols with an average droplet diameter in the low micrometer size range, which is challenging with conventional atomizers. The droplet formation process of the expansion of high‐pressure emulsions was investigated using a plain‐orifice atomizer and different swirl nozzles. The local droplet size and droplet velocities were measured and used to estimate the local Weber number and thus infer the droplet size reduction. Measurements of the local mass concentration in the aerosol showed that, for the swirl nozzle, the highest concentration was found outside of the central axis, indicating radial momentum generated by the swirl nozzle. Furthermore, it was shown that the type of expansion nozzle used has an influence on the resulting median droplet size in the aerosol. For a water mass load of 0.01, the median droplet diameter was reduced from 8 to 3 μm by increasing the swirl number from 0.01 to 0.1. [ABSTRACT FROM AUTHOR]

A negative DC high voltage is used to generate plasma at ambient condition. Self‐organized patterns (SOPs) are formed on the surfaces of the liquid anodes. With increased current or gap distance or reduced gas flow rate, the diameters of SOPs increase and SOPs become more complex, coinciding along with an increases of gas temperature and plasma radius and a decrease of electron density. Both plasma expansion and liquid evaporation in terms of gas temperature, lead to a drop of electron density and pattern formation. Our research elucidates the correlation between SOPs evolution and plasma properties and clarifies the physical process of SOPs formation based on the interaction between atmospheric pressure plasma and liquid anodes. [ABSTRACT FROM AUTHOR]

Cryogenic supercritical hydrogen storage technology is a high-density physical hydrogen storage method, which is a highly promising hydrogen storage approach. However, existing research has mainly focused on the development of storage devices for cryogenic supercritical hydrogen, with limited research on the cooling process of supercritical hydrogen. Therefore, a novel cooling process for cryogenic supercritical hydrogen production based on helium expansion cycle with liquid nitrogen (LN 2) pre-cooling is proposed in this paper. In this process, after being compressed and cooled in multiple stages, the feed hydrogen is pre-cooled by LN 2. Then, cryogenic supercritical hydrogen (10 MPa, −235.15 °C, 63.36 g/L) is obtained by helium multi-stage expansion refrigeration. The process is simulated by Aspen HYSYS and optimized by genetic algorithm (GA) to obtain lower specific energy consumption (SEC). Thermodynamic analyses are conducted to evaluate the process. And compared with the conventional hydrogen liquefaction process, the results show that the proposed process is reasonable and superior. The SEC 0 , figure of merit (FOM), and the total exergy loss of the system are 5.432 kWh/kg H2 , 43.88%, and 289.69 kW respectively. This study indicates that the proposed process has significant implications for the hydrogen industry and provides valuable information for cryogenic supercritical hydrogen storage systems. • A novel high-density cryogenic supercritical hydrogen storage system is proposed. • Twelve key variables in the process are optimized to reduce the energy consumption. • The process has higher exergy efficiency than conventional LH 2 plants. • The volume storage density of hydrogen can reach 63.36 kg/m3 in the system. [ABSTRACT FROM AUTHOR]

Hydrate risk management is critically important for an energy industry that continues to see increasing demand. Hydrate formation in production lines is a potential threat under low temperature and high-pressure conditions where water and light gas molecules are present. Here, we introduce a 1-inch OD single-pass flow loop and demonstrate the Joule-Thomson (JT) expansion of a methane-ethane mixture. Initially, dry gas flowed through the apparatus at a variable pressure-differential. Larger pressure differentials resulted in more cooling, as predicted by standard thermodynamic models. A systematic deviation noted at higher pressure differentials was partially rectified through corrections incorporating heat transfer, thermal mass and kinetic energy effects. A wet gas system was then investigated with varying degrees of water injection. At the lowest rate, hydrate plugging occurred close to the expansion point and faster than for higher injection rates. This immediate and severe hydrate plugging has important implications for the design of safety relief systems in particular. Furthermore, this rate of plugging could not be predicted by existing software tools, suggesting that the atomization of liquids over an expansion valve is a critical missing component that must be incorporated for accurate predictions of hydrate plug formation severity. [ABSTRACT FROM AUTHOR]

We presented a low-cost electronic speckle imaging method for quantifying and monitoring the moderate expansion and contraction of fluids. The system comprises the steps of recording a stack of electronic speckle patterns of the liquid under coherent light illumination, generating velocity vector fields of the temporal dynamic speckle sequence, calculating profile velocity at different temperatures of the liquid, evaluating the inertia moment (IM) of the temporal history of speckle patterns followed by the computation of the co-occurrence matrices. The results show that profile velocity at different temperatures may be used to determine the liquid's thermal state. The test evaluated speckle grain size as a potential criterion for monitoring the liquid's moderate thermal expansion and allowed for the measurement of thermal exchange between the system and its surroundings even at very low temperatures (4 °C). The experiment demonstrates the effectiveness of the laser speckle imaging technique at the macro- and micro-scale molecular dynamics levels. [ABSTRACT FROM AUTHOR]

In single phase flows, benchmarks like the lid driven cavity have become recognized as fundamental tests for newly developed computational fluid dynamics, CFD, codes. For multiphase free surface flows with variable surface tension, the presently studied pool with isothermal sidewalls is suggested as it is the simplest domain where Marangoni effects can dominate. It was also chosen due to its strange sensitivity to the initial setup which is discussed at length from a chosen number of 'scenarios'. It was found that the fluid interface can reverse deformation by a change in the top boundary condition, the liquid equation of state, and the gravity level. For the top boundary condition, this reversal is due to vapor expansion within the closed volume, creating an additional convection mechanism. Not only does the interface reverse, but the peak height changes by more than an order of magnitude at the same Marangoni number. When including gravity, the peak velocity can increase significantly, but it can also cause a decrease when done in combination with a change in the top wall boundary condition. Finally, thermal expansion of the liquid phase causes the peak velocity to be reduced, with additional reductions from the gravity and top wall condition. The differences in each scenario could lead to significant errors in analyzing a practical application of Marangoni flows. Therefore, it is important to demonstrate that a new CFD code can not only resolve Marangoni convection, but also has the capability to resolve the scenario most relevant to the application at hand. [ABSTRACT FROM AUTHOR]

A nonuniform temperature field can deteriorate the performance of sensors, especially those working in the field, such as an optical sensor for oil-tank ground settlement (GS) monitoring. In this case, the GS monitoring employs hydraulic-level-based sensors (HLBS), which are uniformly installed along with the oil-tank basement perimeter and are all connected by hydraulic tubes. Then, the cylinder structure of the oil tank itself can create a strong temperature difference between the sensors installed in the sunlit front and those in the shadow. Practically, this sunlight-dependent difference can be over 30 °C, by which the thermal expansion of the measuring liquid inside the connecting hydraulic tubes keeps on driving a movement and, thereby, leads to fluctuations in the final result of the oil-tank GS monitoring system. Now, this system can work well at night when the temperature difference becomes negligible. However, temperature uncertainty is generated in the GS sensors due to the large temperature difference between the sensors in the daytime. In this paper, we measured the temperature where the sensor was located. Then, we compared the results of the GS sensors with their corresponding temperatures and fitted them with two separate curves, respectively. After observing the similarity in the tendency of the two curves, we found that there was a qualitative correlative relationship between the change in temperature and the uncertainty in the sensor results. Then, a curve similarity analysis (CSA) principle based on the minimum mean square error (MMSE) criteria was employed to establish an algorithm, by which the temperature uncertainty in the GS sensors was reduced. A practical test proved that the standard deviation was improved by 73.4% by the algorithm. This work could be an example for reducing the temperature uncertainty from in-field sensors through the CSA method. [ABSTRACT FROM AUTHOR]

The present study addresses the expansion of pressurized liquid R-290 through a 1.2 mm diameter capillary tube and its subsequent motion through a metastable condition entailing a change of phase through flashing phenomenon. The expansion of R-290 through a helical capillary tube is numerically simulated using a finite volume-based mixture model. For the simulation of the flashing phenomena, a homogeneous equilibrium approach is used. The Zwart–Gerber–Belamri model is deployed to represent mass transfer during flashing. ANSYS Fluent 2021 R2 software has been used for the numerical simulations. A series of UDF (user defined functions) are developed to read the recorded database of R-290 and perform the cavitation modeling. Bilinear interpolation is performed for determining the fluid properties at the corresponding pressure and temperature. The developed numerical model has been validated against the available numerical and experimental results. For the simulations, tubes with lengths of 1200 mm , 1500 mm , 1800 mm , 2100 mm , and 2400 mm have been considered, and the impacts of increasing length on the flow characteristics at the outlet have been determined. In this investigation, the R-290 refrigerant expands from three different condenser pressures of 16, 14, and 12 bar. Evaporator pressure is adjusted from 2 bar to 8 bar to investigate its influence on flow characteristics. The fall in evaporator pressure brings about a flow transition from subsonic to supersonic. The effects of tube length, condenser, and evaporator pressures on mass transfer rate, evaporator entry temperature, mixture quality at the evaporator entrance, and available refrigeration effects have been analyzed. [ABSTRACT FROM AUTHOR]

Cold clusters of molecular hydrogen were created using a pulsed nozzle. The thermodynamical states of the clusters were characterized by measuring the cluster beam velocity and the laser-induced fluorescence (LIF) spectra of embedded molecules. Two distinct velocity components were identified in the beam that originates from different clustering mechanisms. The fast velocity component corresponds to the expansion of H2 from the gas phase, while the slow velocity component corresponds to the expansion from the liquid phase. The velocity distribution of these two components showed no significant difference between the expansions of para and normal hydrogen. In this study, LIF spectroscopy of single Mg-phthalocyanine molecules embedded in the H2 clusters consisting of 105 H2 molecules was used to investigate the properties of the fast component. The observed peak frequencies of the LIF signals, compared to those observed in helium droplets, were used to infer the possible presence of the liquid phase in the fast component of the H2 clusters below 5 K. The shift, linewidth, and splitting in the spectra, which strongly depend on the ortho/para ratio, are attributed to the local configurations of hydrogen in the vicinity of the probe molecules. [ABSTRACT FROM AUTHOR]

The anisotropy of molecular polarizability in liquid crystals is linked to the birefringence in these substances. The classic methods to compute the polarizabilities of liquid crystals assume an average number density of molecules that is equal in all directions. In the present work, a new model is proposed for the anisotropic molar polarization based on a virtual anisotropy of the number density of molecules in the liquid-crystalline material. This new strategy hence allows for the computation of both the anisotropic polarizabilities and the anisotropic thermal-expansion coefficients of liquid crystals. The model is applied to the liquid crystals 4-n-pentyl-4′-cyanobiphenyl and N-(4-methoxybenzylidene)-4-butylaniline, yielding polarizabilities similar to those reported for these materials. For these nematic liquid crystals, the results imply the existence of a positive thermal-expansion coefficient in the direction perpendicular to the director vector throughout the entire nematic temperature range and a negative thermal-expansion coefficient parallel to the director vector near the temperature of the nematic–isotropic transition. At the isotropization temperature, there exists divergent and critical behavior of the anisotropic thermal-expansion coefficients, consistent with the typical discontinuity of volume in first-order transitions. [ABSTRACT FROM AUTHOR]

The mechanisms of picosecond pulse laser ablation in liquid are investigated in a series of large-scale atomistic simulations performed for FeNi targets irradiated in a liquid environment by picosecond laser pulses at a broad range of fluences. The simulations reveal the existence of three fluence regimes featuring different dominant mechanisms of material ejection and nanoparticle formation. These are (1) the low fluence regime, where atomic clusters and small nanoparticles form through the evaporation of metal atoms followed by condensation in a low-density region at the front of the ablation plume, (2) the medium fluence regime, where roughening and decomposition of a top part of a transient spongy structure of interconnected liquid regions leads to the formation of large nanoparticles, and (3) the high fluence regime, where the nanoparticles form primarily at the phase separation front propagating through the ablation plume cooled from the supercritical state by expansion against the liquid environment and mixing with the liquid. The generation of the largest nanoparticles is observed in the medium fluence regime, and both the maximum size of the nanoparticles and the energy efficiency of the material conversion into nanoparticles decrease upon transition to the high fluence regime. Some of the nanoparticles experience extreme quench rates and rapidly solidify under conditions of deep undercooling, yielding a population of defect-rich nanoparticles of interest for practical applications. The results of the simulations are mapped to the conditions realized within a laser spot irradiated by a beam with a Gaussian spatial profile, where different ablation regimes are activated simultaneously in different parts of the laser spot. The spatially and time-resolved maps of the transient nonequilibrium states predicted in the simulations provide a comprehensive picture of the ablation dynamics and a solid foundation for interpretation of the results of time-resolved experimental probing of the initial stage of the ablation process. [ABSTRACT FROM AUTHOR]

This article considers a unit of a unique design created at the Joint Institute for High Temperatures of the Russian Academy of Sciences, which implements the method of a pycnometer of constant volume and variable mass. The data are obtained on the density of liquid potassium on the saturation line and on the 100 atm isobar in the temperature range 336–2030 K. The relationship between the results of the methodology implemented at the Joint Institute for High Temperatures, Russian Academy of Sciences (JIHT RAS) and measurements of the compressibility of water and steam carried out at the Moscow Power Engineering Institute (MPEI), starting with the work of V.A. Kirillina 1953, is noted. The reliability of the experimental data on the density of liquid potassium in 1976–1977 is analyzed in comparison with the results of the new, independent measurements in 1990. The position of the ideal, as in a rarefied gas, coefficient of thermal expansion of the liquid on the saturation line and on the potassium isobar is found. The experimental data on density, compressibility, and ideal thermal expansion coefficients are used to estimate the position of the unit compressibility factor line and the inversion line of the Joule–Thomson effect for dense potassium in the temperature range K and pressures up to kbar. The considered data on the thermodynamic surface of liquid potassium require new experimental and theoretical work and expansion of the list of analyzed properties. [ABSTRACT FROM AUTHOR]

This study is a short communication on progress made in the adaptation of conventional push-rod dilatometry for the measurement of volumetric expansion of liquid salts up to 1300 K. A new crucible design is offered as a practical solution for measurement of liquid salts by this method. Proof-of-concept measurements of the volumetric expansion of sodium chloride (NaCl) are compared to the available data in literature. Measurement of the coefficient of thermal expansion (CTE) of solid NaCl compared favorably to the available data in literature, confirming both magnitude and trend. The average CTE of NaCl (solid) was α ¯ NaCl Solid = 5.63 · 10 - 5 1 K . The volumetric expansion of liquid NaCl was measured as β NaCl Liquid ≈ 3.96 · 10 - 5 1 / K and is essentially constant from the melt point to 1300 K. The volumetric expansion produced by this method is in reasonable agreement with the available published data and previous measurements made by the authors by neutron radiographic technique. [ABSTRACT FROM AUTHOR]

• Dependence on the radius of Pb nanoparticles' melting and freezing temperatures. • Thermal expansion of Pb nanocrystals and nanodroplets in glass determined using SAXS. • Thermal expansion of liquid Pb nanodroplets is much lower than that of bulk Pb. • Undercooling of Pb nanoparticles reaches over 140 K. We investigated the thermal behavior of Pb nanocrystals and Pb nanodroplets embedded in lead-borate glass by small-angle X-ray scattering (SAXS). Analyzing the SAXS intensities recorded in situ during the heating and cooling processes we determined the dependence on the radius of the melting and freezing temperatures of Pb nanoparticles embedded in the glass. Modeled SAXS intensity functions yielded several parameters associated with the theoretical functions characterizing the relationships between nanoparticle radius and melting and freezing temperatures. The temperature-dependent SAXS intensity profiles were further employed to determine the thermal expansion coefficients of Pb nanocrystals and nanodroplets within the glass matrix. Our findings reveal that the coefficient of thermal expansion for solid Pb nanocrystals exceeds that of bulk Pb crystals, underscoring distinctive thermal behavior at the nanoscale. Conversely, the coefficient of thermal expansion for liquid Pb nanodroplets is notably lower than that observed for bulk liquid Pb. [ABSTRACT FROM AUTHOR]

• Characteristics for asymmetric coalescence process of charged conical droplet were experimentally studied in various conditions. • Charge distribution and transportation were analyzed during conical coalescence process. • Liquid bridge expansion and retraction characteristics were quantitatively discussed. • A normalized phase diagram for conical coalescence and recoil of charged droplets is illustrated with the critical transition boundary. The dynamic behaviors of charged droplet coalescence in electric field has drawn much attention over the past decades due to its complex underlying physics and potential industrial application. This work experimentally investigated asymmetric coalescence dynamics of conical droplets in non-uniform electric field. With the effect of electric field, the cone apexes of deformed droplets merged with each other to form a liquid bridge that initially expanded but then retracted back gradually. It was found that the bridge length increased fast at initial conical coalescence and shrank slowly at retraction stage in various conditions. In addition, the effect of electric charge distribution and transportation on liquid bridge evolution behaviors was analyzed. The characteristics of cone angle and contact distance during droplet conical coalescence and recoil processes were quantitatively discussed with consideration of different parameters. Besides, the phase diagram for determining droplet coalescence and recoil was illustrated based on contact distance and electric Bond number, where the critical transition boundary was figured out with a linear increasing trend. [ABSTRACT FROM AUTHOR]

We analyze a Higgs transition from a U(1) Dirac spin liquid to a gapless ℤ2 spin liquid. This ℤ2 spin liquid is of relevance to the spin S = 1/2 square lattice antiferromagnet, where recent numerical studies have given evidence for such a phase existing in the regime of high frustration between nearest neighbor and next-nearest neighbor antiferromagnetic interactions (the J1-J2 model), appearing in a parameter regime between the vanishing of Néel order and the onset of valence bond solid ordering. The proximate Dirac spin liquid is unstable to monopole proliferation on the square lattice, ultimately leading to Néel or valence bond solid ordering. As such, we conjecture that this Higgs transition describes the critical theory separating the gapless ℤ2 spin liquid of the J1-J2 model from one of the two proximate ordered phases. The transition into the other ordered phase can be described in a unified manner via a transition into an unstable SU(2) spin liquid, which we have analyzed in prior work. By studying the deconfined critical theory separating the U(1) Dirac spin liquid from the gapless ℤ2 spin liquid in a 1/Nf expansion, with Nf proportional to the number of fermions, we find a stable fixed point with an anisotropic spinon dispersion and a dynamical critical exponent z ≠ 1. We analyze the consequences of this anisotropic dispersion by calculating the angular profiles of the equal-time Néel and valence bond solid correlation functions, and we find them to be distinct. We also note the influence of the anisotropy on the scaling dimension of monopoles. [ABSTRACT FROM AUTHOR]

The emptying of a tubular channel as a result of the outflow of a boiling liquid from its one end subjected to a sudden seal failure was investigated. The case where the liquid outflows from the channel in the sluggish regime in which the lag efforts are insignificant and, consequently, the rate of emptying of the channel is mainly determined by the hydraulic losses and the effects of adiabatic expansion of the boiling liquid was considered. It is shown that the system of equations defining the outflow of the liquid from the channel in the two limiting cases where the hydraulic friction force acting on the liquid flow in the channel changes linearly with change in the flow velocity and where this force changes by the square law can be reduced to one nonlinear equation. Self-similar solutions of the problem on the sudden loss of the sealing at one end of the channel have been constructed. [ABSTRACT FROM AUTHOR]

Liquid phase disturbances are often observed in pre-breakdown processes; however, their dynamic behaviors are rarely studied. In this paper, time evolution characteristics of liquid phase disturbance under ultra-long pulses (>100 ms) were investigated. The results showed that the steady expansion of liquid phase disturbance follows the pattern of constant heating power, volume growth rate, and liquid temperature (about 52 °C unvaried with applied voltage). The shrinkage of liquid phase disturbance with the applied voltage leads to the breakdown transition from a full disturbed phase mode to a partial disturbed phase mode. Further research indicated that the liquid phase disturbance has a significant influence on the development of subsonic streamers (especially for positive polarity). In the disturbed phase of liquid, the streamers propagate faster with a plump morphology than in the stationary phase. The local turbulences at the boundary of the disturbed phase can retard the streamer propagation remarkably and lead to the streamer branching. Finally, the abnormal downtrend of positive streamers' average velocity varied with the applied voltage due to the shrinkage of liquid phase disturbance was predicted and observed for the first time. [ABSTRACT FROM AUTHOR]

It is generally believed that ionic/zwitterionic surfactants have strong interactions with each other. However, our experiments found that nonionic/ zwitterionic surfactants exhibit strong synergistic effects, which differs from the previous understanding. In this study, a scCO 2 foam system stabilized by the synergistic action of alkyl glucoside (APG-10, nonionic surfactant) and erucamide propyl betaine (EAB, zwitterionic surfactant) was constructed. Through the measurement of drainage and coarsening characteristics, surface properties, bulk rheological properties, dynamic light scattering (DLS) and Cryo-scanning electron microscopy (SEM), the stabilizing mechanism of the synergistic action of APG-10 and EAB was revealed for the first time at the macro and micro levels. The results indicate that APG10 and EAB exhibit mixed adsorption at the interface, resulting in a denser molecular arrangement at the interface and enhancing the foaming ability. At 80℃ and 8 MPa, compared to the EAB foam system, the drainage half-life of the EAB+APG-10 system increased by 276.9 %, and the Ostwald ripening rate decreased by 62.4 %. Rheological studies have shown that the zero shear viscosity of the EAB+APG-10 system is 6837.8 mPa·s, with an increase of 44.4 % compared to the EAB system at 80℃. This is believed to be mainly due to the binding of APG-10 to the micellar structure to enhance the entanglement strength of the micelles, aiding in suppressing the expulsion and deformation of foam bubbles. Additionally, the mixed system exhibits larger G' and E', effectively suppressing the expansion and contraction of the liquid film. Finally, the sizes and distributions of micellar aggregates were measured by DLS and Cryo-SEM, confirming the presence of wormlike micelles and their distribution within the liquid film. The results of this work provide theoretical support for the development and application of the novel VES-scCO 2 foam fracturing fluid system, which contributes to the efficient extraction of unconventional oil and gas. [Display omitted] [ABSTRACT FROM AUTHOR]

The dynamics of droplet adsorption at the liquid-liquid interface of parallel flow in a microchannel is investigated. The adsorption process is divided into three distinct stages: the liquid bridge expansion stage, the rapid deformation stage and the spreading stage. The dynamic behavior of droplet adsorption is elucidated by quantitatively analyzing the evolution of adsorption length and droplet height over time under different droplet viscosities. This experiment makes a positive contribution to further reveal the droplet adsorption mechanism and expand the application prospect of microfluidic technology. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new and effective Pb-Bi bond-order-potential (BOP) was constructed. • BOP model could accurately describe various properties of binary Pb-Bi system. • Formation, diffusion, viscosity of lead-bismuth eutectic melt was successfully predicted. Lead-bismuth eutectic (LBE) alloys are currently considered one of the most promising liquid metal coolants for fast reactors, and especially accelerator-driven systems (ADS). An analytical bond-order potential (BOP) of Pb-Bi has been constructed to account for the electronic interactions and angular contribution of Pb-Bi system. The newly developed BOP has been validated to show a better performance than the Pb-Bi potentials already published in the literature. Molecular dynamics simulations based on current BOP has been adopted to investigate various properties of Pb-Bi binary system. It accurately predict the heats of formation, density, and thermal expansion coefficient of liquid LBE at 700 K. The diffusion coefficient and viscosity of liquid Pb 44.5 Bi 55.5 are calculated, which are in good agreement with experimental observations in the literature. These findings provide a foundation for future design of Pb-Bi eutectic alloys for use in ADS and heavy-metal-cooled fast nuclear reactors. [Display omitted] [ABSTRACT FROM AUTHOR]

The two-phase expansion inside the expander could be divided into the non-equilibrium flash of superheated liquid and the expansion of the vapor. A higher flash rate would permit higher recovered expansion work. However, it is almost impossible to measure the flash rate inside the expansion chamber. In this paper, an equivalent expansion method s was proposed to study the non-equilibrium flash process for the two-phase expansion. The flash was controlled inside a constant volume flash chamber, which was connected to a vacuum tank to introduce and adjust the flashed vapor rate out of the flash chamber. The flash process inside the chamber was controlled under the working conditions similar to that inside the two-phase expander. By applying the equivalent expansion method, the flash rate could be measured easily. The experiments were carried out with an initial liquid height inside the chamber from 110 to 175 mm, and an initial liquid temperature from 110 to 130 °C with water as the working fluid. The instant flash rate and the P V diagram of the equivalent two-phase expansion were studied. Results showed that the instant flash rate increased and decreased sharply at first, and then the flash became gentle. Thus, the non-equilibrium flash of the two-phase expansion was divided into two stages of the rapid expansion process and the gradual expansion process. It was found that most of the flashed mass was generated during the rapid expansion process. Finally, a non-equilibrium flash model was proposed to simulate the flash process during the two-phase expansion process with the accuracy of ±3.7% predicting the pressure profile and the accuracy of ±2.7% predicting the expansion work. • Instant flash rate of two-phase expansion is obtained by equivalent expansion method. • The sharp jump stage of the instant flash rate was defined as the rapid flash. • Rapid flash is valuable to power recovery ratio considering the expander design. • The new non-equilibrium flash model predicted the flash process with high accuracy. [ABSTRACT FROM AUTHOR]

In order to study the possible negative effects of alkali treatment on the properties of wheat straw/PVC composites under water exposure environment, the water absorption deterioration test of wheat straw/PVC composites prepared by wheat straw with different concentrations of alkali treatment was carried out, and the water absorption behavior and deterioration mechanism of the composites were revealed. The results showed that alkali treatment increased the water absorption of the composites and led to more serious deterioration of the properties of the composites than untreated composites with the continuous immersion in the water exposure environment. In this paper, the possible negative effects of water absorption deterioration of alkali treatment reinforced wood-plastic composites were studied innovatively, it was considered that alkali treatment as a commonly used chemical treatment method should fully consider the negative effects of material types and use environment on its strengthening effect, and the research results can provide theoretical reference for the performance improvement of follow-up composites in water exposure environment. [Display omitted] • The negative effects of alkali treatment on the application of WPCs in water exposure environment be revealed. • Proved that the faster water absorption rate of the alkali-treated WPCs leads to the deterioration of composites. • The deterioration mechanism of WPCs is the destruction of interface caused by liquid diffusion and the expansion of fibers. [ABSTRACT FROM AUTHOR]

This paper revisits the experimental assessment of the thermal volume expansion behaviour via the novel technique of Temperature-modulated optical refractometry (TMOR) and compares it to two classical dilatometry techniques: Oscillating dilatometry (OD) and Thermo-mechanical analysis (TMA). This is done at the example of a model liquid (n -tetradecane, C 14 H 30) and a homogeneous and isotropic, cross-linked epoxy thermoset in the viscoelastic state. It is shown that the thermal volume expansion coefficients of C 14 H 30 obtained via TMOR and OD agree exceptionally well with each other and indeed reflect thermodynamic constants, if certain experimental boundary conditions are met. In the case of TMA analyses of the epoxy thermoset, the measured data was found to be biased rather easily, especially due to the tracking force that induces additional shape changes beyond thermal expansion. The controlled combination of TMOR and TMA allows differentiating between a "true" thermal volume expansion behaviour and additional shape changing effects. • Comparison of a novel optical dilatometer (TMOR) to thermo mechanical analysis (TMA). • TMOR is able to assess the "true" thermal volume expansion of polymers and liquids. • TMA can impose unwanted shape changes to thermosets in the viscoelastic state. • Viscoelastic thermosets are morphologically very close to related liquids. • The combination of TMOR and TMA allows access to the flowability of polymers. [ABSTRACT FROM AUTHOR]

In this work, we describe the design and development of an in situ neutron reflectometry cell for high temperature investigations of structural changes occurring at the interface between inorganic salts, in their molten state up to 800 °C, and corrosion resistant alloys or other surfaces. In the cell, a molten salt is confined by an annular ring of single crystal sapphire constrained between the sample substrate and a sapphire plate using two gold O-rings, enclosing a liquid salt volume of 20 ml, along with a dynamic cell volume to accommodate expansion of the liquid with heating. As a test case for the cell, we report on an in situ neutron reflectometry measurement of the interface between a eutectic salt mixture of MgCl2–KCl (32:68 molar ratio) and a single crystal sapphire substrate at 450 °C, resulting in the formation of a 60 Å layer having a scattering length density of 1.72 × 10−6 Å−2. While the origin of this layer is uncertain, it is likely to have resulted from the salt reacting with an existing impurity layer on the sapphire substrate. [ABSTRACT FROM AUTHOR]

The in vitro erythrocyte differentiation model remains a strong, clinically relevant tool to model erythroid development in normal and disease related hematopoiesis. This model also has application to developing therapeutics for diseases related to red blood cells such as sickle cell anemia where targeting increased expression of fetal hemoglobin has been a major emphasis. Since the original protocol's publication in 2002, many groups have published modified methodologies to address issues in efficiency of maturation and terminal enucleation, as well as in scalability. While all reports have merit and show efficient enucleation, the methodologies used vary widely in technique and cytokine content. Additionally, despite the strengths in these methods, reproducibility of efficient differentiation to the point of differentiation is difficult. To address these limitations, we developed a streamlined process where total PBMCs are first primed using the original liquid culture expansion phase (published in 2002) before being differentiated with minimal input via standardized, commercially purchased semi-solid medium culture pre-supplemented with erythropoietin. Our data show this methodology to produce similar levels of CD235/CD71 positivity as previous methods but with enhanced CD235 solo positivity and evidence of enucleated cells in comparison with other widely used methods. Given the difficulty and wide variation in in vitro differentiation techniques, we present this methodology as a streamlined methodology for production of mature erythroid cells with minimal input using easily purchased reagents. [ABSTRACT FROM AUTHOR]

Lost circulation in the surface layer of shale gas is a significant problem caused by stratum weathering and erosion, crack development, and other factors. To address this issue, an environment-friendly plugging agent AT-SPS was used for plugging according to the principle of expansion of liquids. The results of laboratory performance evaluation showed that the plugging agent immediately reacted with water, expanded by several times, and produced a water-fast induration, which filled and plugged the leaking channel. Based on the expansion characteristics of the plugging agent and the characteristics of the karst cave leakage in Changning shale gas, the application process has been formulated. The plugging agent is injected into the leaking layer using a special transport instrument. After coming into contact with water, the plugging agent immediately engaged in rapid reaction, and produced a solid induration, which plugged the leaking layer and the water layer. The plugging agent has been applied in a shale gas well in Changning for 4 wells, which greatly reduced the leakage, stabilized the well wall and ensured that shaft drilling could proceed to the intended depth. This study introduced the basic principles, experimental evaluation, and application process of the environment-friendly water-swelling plugging agent, laying a foundation for further field applications. [ABSTRACT FROM AUTHOR]

The rotational motion of molecules in the liquid phase has been shown to be one of the main factor that determines the liquid's thermal expansion and can be used for its calculation based on an expression for the partition function of the rotational motion of ideal gas molecules, taking into account the contribution of intermolecular interactions. This study establishes that the thermal expansion temperature coefficients are grouped in sequences depending on the functional class of compounds. The general hydrocarbon sequence breaks down into separate sequences according to their functional groups, such as saturated or aromatic hydrocarbons. Thus, it is shown a correlation between the thermal expansion of liquids with an average size of molecules, at temperatures well below the boiling point, and the entropy of the rotational motion which is a function of the moments of inertia of molecules and temperature. [ABSTRACT FROM AUTHOR]

The thermophysical properties of refractory MoNbReTaW high-entropy alloy in both supercooled liquid and high-temperature solid states were explored by an electrostatic levitation technique. The maximum supercooling attains 504 K, and the hypercooling limit is derived as 571 K. The liquid density at liquidus temperature is measured to be 13.3 g cm−3, which increases linearly with decreasing temperature at a slope of 6.83 × 10−4 g cm−3 K−1. The liquid alloy exhibits 5.3% relative volume shrinkage during crystallization. The thermal expansion coefficient of liquid and solid alloy at liquidus temperature are determined as 5.0 × 10−5 K−1 and 3.6 ×10−5 K−1, respectively. The liquid specific heat at liquidus temperature is found to be 38.2 J mol−1 K−1, and basically displays a linear decreasing tendency with temperature. According to the calculated enthalpy of fusion 24.7 kJ mol−1 and measured specific heats, the temperature-dependent entropy and Gibbs free energy difference between supercooled liquid and crystalline solid are obtained. [ABSTRACT FROM AUTHOR]

We introduce a theoretical and experimental framework that enables quantitative measurements of the temperature and magnetic field profiles governing the thermo-magnetic write process in heat assisted magnetic recording. Since our approach allows the identification of the correct temperature dependence of the magneto-crystalline anisotropy field in the vicinity of the Curie point as well, it provides an unprecedented experimental foundation to assess our understanding of heat assisted magnetic recording. [ABSTRACT FROM AUTHOR]

When a drop of fluid hits a small solid target of comparable size, it expands radially until reaching a maximum diameter and subsequently recedes. In this work, we show that the expansion process of liquid sheets is controlled by a combination of shear (on the target) and biaxial extensional (in the air) deformations. We propose an approach toward a rational description of the phenomenon for Newtonian and viscoelastic fluids by evaluating the viscous dissipation due to shear and extensional deformations, yielding a prediction of the maximum expansion factor of the sheet as a function of the relevant viscosity. For Newtonian systems, biaxial extensional and shear viscous dissipation are of the same order of magnitude. On the contrary, for thinning solutions of supramolecular polymers, shear dissipation is negligible compared to biaxial extensional dissipation and the biaxial thinning extensional viscosity is the appropriate quantity to describe the maximum expansion of the sheets. Moreover, we show that the rate-dependent biaxial extensional viscosities deduced from drop impact experiments are in good quantitative agreement with previous experimental data and theoretical predictions for various viscoelastic liquids. [ABSTRACT FROM AUTHOR]

Biomass conversion to organic products is expected to be a core technology for the future sustainable society. Still, published studies show that the energy cost and environmental impact of making organic products from biomass are often worse than making those products from fossil fuels. The problematic step in biomass conversion is the removal of water. Unless the environmental and energetic costs of separating water from organic products can be lowered, bio-derived products will struggle to be greener and cheaper than fossil-derived products. We propose a new method for separating organic products from water: high pressure switchable water (HPSW). HPSW is a process that combines two known phenomena: CO2 expansion of liquids (CXL) and CO2-switchable water (SW). HPSW takes advantage of the benefits of changing the polarity of organic liquids at high CO2 pressures and the repulsive amine-solute interactions that occur after SW amines are exposed to CO2, both contributing to the removal of the organics from water. Each process alone can trigger the separation of some organics from water, but individually they are not efficient for removing hydrophilic organic solutes. We hypothesised that CXL and SW, if performed simultaneously, would act synergistically and promote more efficient and cleaner separations. For test mixtures of acetone and water, we demonstrated that several amine ionogens could promote phase separation of the acetone from water at lower pressures than CXL alone. 2,6,10-Trimethyl-2,6,10-triazaundecane (TMTAD) was one of the best amines tested, decreasing the separation pressure to 3 bar of CO2 compared to 30 bar without an ionogen. In addition, 93% of the initial TMTAD added to the mixture was recovered using reverse osmosis (RO). If HPSW can reduce the energy consumption of separations, the current separation issues faced by the biomass conversion sector might be overcome. [ABSTRACT FROM AUTHOR]

This study aims to investigate a laser ultrasound (LUS) transducer for high-temperature (>100 °C) applications. For decades, many researchers have investigated efficient LUS transducers, yet studies on laser ultrasound transducers capable of performing at the high-temperature condition are rarely found in the literature. Most current LUS transducers still utilize a polymer-based composite material, that is, not stable at varying temperature conditions. This study introduces a liquid metallic (LM) LUS transducer that utilizes field's metal, which has a high thermal expansion (∼3 × 10−4 K−1). We hypothesized that such a high thermal expansion of the liquid metal can effectively produce laser-generated ultrasound waves, substituting for conventional polymer-based transducers. A numerical simulation predicted that the LM LUS transducer would produce higher LUS intensity (∼22 dB) than that without the LUS transducer. Experiment results confirmed that the LM transducer effectively intensifies the ultrasound wave signals, obtaining a signal-to-noise gain over 30 dB. Moreover, the transducer was found capable of transmitting detectable wave packets in relatively high-temperature conditions (∼400 °C), while conventional candle soot nanoparticle-polydimethylsiloxane could not perform stably at these elevated temperatures. The investigations introduced in this article are scientifically significant since we demonstrated the engineering feasibility of liquid metallic materials for LUS transducers. [ABSTRACT FROM AUTHOR]

The hydrophobicity of poorly soluble drugs can delay tablets disintegration. We probed here the influence of different disintegrants on the disintegration of challenging hydrophobic formulations. Tablets containing diluents, hydrogenated vegetable oil and either sodium starch glycolate (SSG), croscarmellose sodium (CCS) or crospovidone (XPVP) were prepared. The disintegration time of tablets was tested immediately and after storage at 40 °C and 75% RH in sealed bags. Results show that storage and compression force had a negative effect on disintegration, particularly with 1% disintegrant. The performance of the three disintegrants was in the following order: CCS (best) > SSG > XPVP. For example, tablets containing 1% CCS, SSG and XPVP, compressed at 20 kN, disintegrated in ≈3, ≈12 and ≈69 min, respectively, after two months storage. Settling volume, liquid uptake and effect of storage on physical properties of the pure disintegrants were also studied and revealed that the reduced performance of XPVP is related to: 1) its rapid, yet short-range expansion upon liquid exposure and 2) its change of behaviour on storage. In conclusion, CCS ensured rapid disintegration at low concentration across various compression forces and storage times. Thus, the use of CCS in hydrophobic tablet formulations is recommended. [ABSTRACT FROM AUTHOR]

Thermal stability of optical near field transducers is an important issue for heat-assisted magnetic recording (HAMR), which affects HAMR system lifetime. In this paper, dark-field scattering spectroscopy was used to study the stability of nanometer-scaled Au lollipop transducers that were subjected to thermal annealing. Variation in relative peak intensity and red-shifting in peak position can be observed in scattering spectra for transducer after annealing. Based on the optical characterizations on Au thin films and calculations of Mie scattering by finite-difference time domain simulations, the measured changes in transducer scattering properties can reflect annealing-induced variations in optical properties and dimensional feature size for the Au lollipop transducer. Dark-field scattering spectroscopy can be a promising method to examine HAMR near field transducer thermal stability. [ABSTRACT FROM AUTHOR]

• Spreading chticsaracteris of the two fluid spray nozzle were investigated • The viscosities of the liquids were determined experimentally • Volume of Fluid computational model was used for computational analysis • Experiments for 5 liquids at 3 temperatures and 3 nozzle diameters were performed • The results of numerical simulation are compared with appropriate experimental data Spray nozzles are widely used in processing industry for spreading evenly large amount of fluids. The expansion of fluid depends on the nozzle type, the parameters of the nozzle and the characteristics of the working fluids. The experiments were performed for five fluid types used in food/pharma/animal feed application (glycerol, soybean oil, molasses, hydroxypropyl methylcellulose, tara gum), three diameters of the nozzle (1 mm, 3 mm, 5 mm) and three fluid temperatures (40 °C, 50 °C and 60 °C). An experimentally validated numerical model was developed, based on laminar two-phase flow, investigating different liquids, assuming the ideal gas flow, applying the finite volume method and volume of the fluid model with interface tracking. The effects of liquid parameters, nozzle diameter and liquid temperature on the characteristics of the jet were also analysed by artificial neural network model. The nozzle diameter strongly influenced the spreading characteristics of the jet, while the temperature affected the liquid viscosity. The increase of the temperature also led to the augment of the spreading angle of the fluid passing from the nozzle and also the enhancement of the spaying liquid expansion. [ABSTRACT FROM AUTHOR]

In this work, the expansion dynamics of liquid tin micro-droplets irradiated by femtosecond laser pulses were investigated. The effects of laser pulse duration, energy, and polarization on ablation, cavitation, and spallation dynamics were studied using laser pulse durations ranging from 220 fs to 10 ps, with energies ranging from 1 to 5 mJ, for micro-droplets with an initial radius of 15 and 23 μ m. Using linearly polarized laser pulses, cylindrically asymmetric shock waves were produced, leading to novel non-symmetric target shapes, the asymmetry of which was studied as a function of laser pulse parameters and droplet size. A good qualitative agreement was obtained between smoothed-particle hydrodynamics simulations and high-resolution stroboscopic experimental data of the droplet deformation dynamics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bi-color laser ablation is more efficient when a shorter-wavelength pulse comes first. • A visible fs pulse generates free electrons efficiently absorbing the next IR pulse. • Bi-color fs-laser ablation is especially strong at pulse separations of around 100 ps. • High-quality craters are produced at laser pulse separation on a 100-ps timescale. • Dual-wavelength ultrafast-laser pulses offer a better control of energy deposition. An experimental and theoretical study of laser-induced damage and ablation of silicon by two individual femtosecond pulses of different wavelengths, 1030 and 515 nm, is performed to address the physical mechanisms of dual-wavelength ablation and reveal possibilities for increasing the ablation efficiency. The produced craters and damaged areas are analyzed as a function of laser fluence and time separation between the pulses and are compared with monochromatic irradiation. The order of pulses is demonstrated to be essential in bi-color ablation with higher material removal rates when a shorter-wavelength pulse arrives first at the surface. Simulations based on the two-temperature model show that the visible pulse is profitable for the generation of the electron-hole plasma while the delayed IR pulse is efficiently absorbed in the plasma enhancing energy coupling to the target. At long delays of 30–100 ps, the dual-wavelength ablation is found to be particularly strong with formation of deep smooth craters. This is explained by the expansion of a hot liquid layer produced by the first pulse with a drastic decrease in the surface reflectivity at this timescale. The results provide insight into the processes of dual-wavelength laser ablation offering a better control of the energy deposition into material. [ABSTRACT FROM AUTHOR]

Confined spaces (e.g., containers, underground warehouses) are common storage places for storage tanks. The safety of confined spaces subjected to boiling liquid expansion vapour explosions (BLEVEs) is of vital significance but still not fully understood. In this study, a small visualization device was used to research the rapid depressurization in confined space. The effect of confined space on the rapid boiling mechanism and two-phase flow of liquids and vapours was investigated. The buffer of the confined space on the superheated boiling of liquids under different leakage conditions is researched by the pressure characteristic parameters. The results show that the superheated liquid leakage process is divided into three stages, i.e., rapid depressurization, slow depressurization, and pressure balance. In the stage of rapid depressurization, the nucleation and growth processes of bubbles can be mainly divided into static, bubble flow, and bullet flow. The vaporization of the leakage flow in the explosion-vented tank will decrease the depressurization rate to buffer the boiling explosion of the storage tank. Thus, as the release pressure increases, the average rate of pressure change increases in both vessels will accelerate the arrival of buffering in the confined space like the explosion-vented tank. In a small-discharge area ratio regime, the pressure change rate in both vessels increases as the discharge area ratio increases. In a large-discharge area ratio regime, the superheat degree no longer affects the pressure change rate due to the buffer of rapid vaporization and saturation of the explosion-vented tank. Finally, the effect of the confined space has been quantified to clarify why BLEVE does not occur in the confined space. This study deepens the understanding of complex failure and rapid depressurization in confined spaces and provides insights into the fire hazards of BLEVE accidents in confined spaces. [ABSTRACT FROM AUTHOR]

The thermophysical properties of liquid Fe 84 Nd 10 B 6 alloy from superheated to undercooled state were investigated by space simulation technology combined with ab initio molecular dynamics (AIMD) simulations. The liquid density at liquidus temperature and its temperature coefficient were determined as 7.17 g·cm−3 and 5.51 × 10−4 g·cm−3·K−1, while its liquid thermal expansion coefficient was measured as 7.69 × 10−5 K−1. The ratio of specific heat to emissivity decayed as a quadratic power function. Under electrostatic levitation (ESL) condition, even though the cooling rate of liquid alloy was only 23.6–35.3 K/s, a maximum 131 K undercooling was realized. As alloy undercooling rose, the grain size of primary α(Fe) dendrite was refined, whose volume fraction decreased from 26.2% to 22.0%. Meanwhile, the volume fraction of major peritectic τ 1 (Nd 2 Fe 14 B) phase was increased from 68.6% to 76.8%, which was accompanied by the reduction of peri-eutectoid τ 2 (Nd 1.1 Fe 4 B 4) phase down to 1.2%. In the case of microgravity processing by drop tube, liquid undercooling and cooling rate respectively reached up to 260 K (0.16 T L) and 3.9 × 104 K/s for the falling alloy droplets. Instead of τ 1 phase, the primary α(Fe) phase occupied the largest volume fraction of 49.7% in large alloy droplets. At enhanced undercooling and cooling rate, the peritectic τ 1 phase only increased from 26.2% up to 43.5%, whereas those of α(Fe) and τ 2 phases declined to 44.0% and 12.5%, respectively. It was found that the increase of liquid alloy undercooling promoted the peritectic transformation to some extent, but high cooling rate greatly restricted peritectic reaction by reducing reaction time. The coupled effect of liquid undercooling and cooling rate controlled the volume fraction of each phase in rapidly solidified microstructures. • The thermophysical properties of liquid Fe 84 Nd 10 B 6 alloy are measured through space simulation technology. • The rapid solidification of liquid Fe 84 Nd 10 B 6 alloy is realized under electrostatic levitation and microgravity conditions. • Constituent phases in rapidly solidified microstructures are controlled by coupled effect of undercooling and cooling rate. [ABSTRACT FROM AUTHOR]

• The influence mechanism of E and D is revealed by experiments and simulations. • Increasing E strengthens the electric field distortion and charge polarization. • The high-pressure gradient region is easier to form in large D. • The vertical collapse evolution is suppressed with the increase of E and D. Under high-strength electric fields, partial coalescence may occur, thus producing fine secondary droplets, which are undesirable for separating water from oil. In this study, experimental and numerical methods are employed to investigate the coalescence behavior under a DC electric field to comprehensively understand the effect of electric field strength (E) and droplet diameter (D) on coalescence. The Level-set method is employed to capture the moving interface, and the numerical data are validated through experimental tests. The results reveal the easy formation of secondary droplets with increasing E and D values. In particular, the electric field strength suppresses the expansion of the liquid bridge and hinders the vertical collapse of the droplets. The distortion of the electric field at the liquid bridge and the polarized charge both increase with E , thus resulting in stronger electric field repulsion. Moreover, the enhancement in D significantly affects the shrinkage of the liquid bridge and prevents the vertical collapse of the droplet. The pressure gradient at the liquid bridge from the outside to inside decreases as a function of D , thereby inhibiting the contraction speed. Furthermore, the number of polarized charges concentrated on the top of the droplet increases, thus resulting in an enhanced electric field tension. The results obtained herein can potentially act as guide for the design and optimization of electric dehydrators. [ABSTRACT FROM AUTHOR]

Ultrasound focusing and microbubble collapse are numerically investigated using a level-set interface tracking method for two-phase flows with multiple interfaces. The computations for ultrasound propagating through a spherical lens demonstrate the ultrasound refraction and pressure intensification at the rear of the lens. The focusing of the initial negative pressure wave through the lens induces a converging flow and the focusing of the subsequent positive pressure wave further intensifies the pressure at the lens. Computations are extended to bubble oscillations near the focusing lens and compared with the no-lens case. The lens not only amplifies the bubble expansion and contraction rates significantly but also generates a larger pressure gradient across the bubble. This ultrasound focusing effect contributes to the asymmetric collapse of the bubble and the formation of a liquid jet that penetrates the bubble. The effects of lens size, initial bubble radius and bubble-lens distance on bubble expansion and liquid jet are further investigated. • A numerical investigation of ultrasound focusing and bubble collapse is presented. • Spherical lenses show great ultrasonic pressure intensification at the lens surface. • Ultrasound focusing contributes to asymmetric bubble collapse and liquid jetting. • The effects of initial bubble size, lens size and bubble-lens distance are analyzed. [ABSTRACT FROM AUTHOR]

Steam‐driven eruptions are explosive events that are fueled by pressurized water and steam trapped within rock and sediments. We show how rock properties modulate explosion size, dynamics, and hazard footprint based on examples from Lake Okaro (New Zealand). Laboratory decompression experiments demonstrate that fragmentation of strong/unaltered host rocks comes with a high energy cost (∼10%–11% of bulk explosion energy). Consequently a low energy fraction (∼7%–8%) remains for kinetic energy and thus particle ejection. In contrast, disaggregation of unconsolidated sediments requires little energy (<2%–7%), allowing higher outputs of kinetic energy (22%–25%), and more efficient debris dispersion. Experimental estimates of bulk explosive energies are consistent with both field observations and empirical models applied to Lake Okaro crater dimensions. This integration of experimental methods, field observations, and empirical modeling underscores the dominant role of alteration state and host rock lithology when estimating crater‐forming and ballistic hazards in volcanic/geothermal areas. Plain Language Summary: Steam‐driven eruptions are explosions that frequently occur in volcanic and geothermal areas. They are powered by the sudden release and expansion of steam and liquid water trapped under high pressure within the pore spaces of host rocks. Here we have experimentally studied how the strength of rock hosting steam and liquid controls the nature of explosions. Specifically, we used experiments to estimate the relative amounts of energy that goes into breaking rock up, versus that required for ejecting particles upwards and outwards. We used natural rock samples collected from well‐studied explosion craters at Lake Okaro (New Zealand). Experiments recreated pressures and temperatures of the geothermal system and allowed sudden decompression of water saturated rock. We demonstrated that the porosity, permeability, and strength of rocks is well reflected in different experimental behaviors. Experiment data was scaled to field settings and natural examples. This showed that stronger rocks require much energy to break, hence, if they are the dominant host rocks, less energy is available for particle ejection. This implies a smaller hazard footprint. Future hazard assessment for steam‐driven eruptions should take these findings into account. Key Points: Experimental calculations can be scaled to crater sizes yielding estimates of energy partitioning for fragmentation and ejection processesUnconsolidated and weak lithologies disaggregate with low‐energy, producing larger craters and ejecta volumes with greater hazard footprintsHard‐rock requires more energy to fragment, which results in smaller craters, lower ejecta volumes and smaller hazard footprints [ABSTRACT FROM AUTHOR]

Density measurements are made on a series of caesium–lead liquid alloys containing 20 to 70 at.% Pb, in a temperature range from the liquidus line to ~1000 K. The experiments are carried out using the gamma-ray attenuation technique. Based on the obtained results, the concentration dependences of the molar volume, relative excess molar volume and volumetric coefficient of thermal expansion of the caesium–lead liquid system are described. These dependences strongly deviate from the corresponding dependences for ideal solutions, which confirms a tendency for compound formation in Cs–Pb melts. [ABSTRACT FROM AUTHOR]