Vapor–liquid and liquid–liquid equilibrium for binary systems ester + a new protic ionic liquid

This study reports the synthesis of a new protic ionic liquid, bis(2-hydroxyethyl)ammonium butyrate (2-HE₂AB), performed by a Brønsted acid–base reaction between butanoic acid and bis(2-hydroxyethyl)ammonia. The new ionic liquid was characterized by 1D hydrogen NMR spectrum. The ionic liquid shows complete solubility in water, methanol, and ethanol, and is partially soluble in methyl acetate, ethyl acetate, and propyl acetate, while it is not soluble in some alkanes. Density, refractive index, and vapor–liquid equilibrium were measured for the binary system 2-HE₂AB + methyl acetate at atmospheric pressure. Furthermore, density, refractive index, and liquid–liquid equilibrium were measured for the binary systems 2-HE₂AB + ester (methyl acetate, ethyl acetate, or propyl acetate) at 293.2 K. The Peng-Robinson equation of state, coupled with the Wong-Sandler mixing rule, was used in the thermodynamic modeling of density, vapor–liquid, and liquid–liquid equilibrium data. The COSMO-SAC activity coefficient model was used to calculate the activity coefficient within the Wong-Sandler mixing rule. The calculations show deviations for density, for the vapor–liquid equilibrium, and for the non-polar and polar phases of the liquid–liquid equilibrium within 13.0, 0.1, 132.5, and 23.8 %, respectively.     

Zigzag instability of a χ disclination line in a cholesteric liquid crystal

We studied the formation of χ disclination lines in planar cholesteric samples placed in a temperature gradient near the cholesteric to smectic A phase transition. We observed that the first simple line which forms close to the smectic-cholesteric front zigzags when it is perpendicular to the direction of planar anchoring and is straight for other orientations. This instability is similar to Herring instability for crystalline surfaces. We show numerically that it originates from a strong increase of the elastic anisotropy close to the transition. In addition, we propose a new method to measure the pitch divergence at the smectic to cholesteric phase transition.     

Analysis of a 2D “liquid” plasma lattice

To study the structural and dynamical properties of a 2D dusty plasma lattice, a set of experiments were performed in an environment of radio frequency discharge. Based on the results of one of the experiments, pair correlation function, bond-orientational correlation function and mean square displacement of such a system were computed and analyzed. The bond-orientational correlation function is found to fit in with the law of e-r, and the mean square displacement is found to increase monotonously with time, both of which, together with the pair correlation function, indicate that the two-dimensional dusty plasma lattice formed in the experiment stayed in a "liquid" state.     

How reproducible are dynamic heterogeneities in a supercooled liquid?

The particle dynamics in a liquid exhibits a transient spatial distribution of dynamic heterogeneities. The relationship between this kinetic structure and the underlying particle configuration remains an outstanding problem. In this Letter, we present a general simulation technique for identifying the features of the dynamic heterogeneity which arise due to a specific configuration, as distinct from the random spatial variation due to the intermittent particle dynamics.     

Novel cell parameter determination of a twisted-nematic liquid crystal display

In this paper a novel method is proposed to determine the cell parameters including the twist angle, optic retardation and rubbing direction of twisted-nematic liquid crystal displays （TNLCD） by rotating the TNLCD. It is a single-wavelength method. Because using subtraction equation of transmittance as curve fitting equation, the influence of the light from environment and the absorption by polarizer, the sample of TNLCD and analyser on the transmittance is eliminated. Accurate results can also be obtained in imperfect darkness. By large numbers of experiments, we found that not only the experimental setup is quite simple and can be easily adopted to be carried out, but also the results are accurate.     

Analysis of a 2D “liquid”plasma lattice

Adustyplasmacanbedefinedasacomplicatedplasmacontainingsmallsolidmattercalleddustgrainsordustparticles,whichareusuallychargednegatively,duetoelectronshighermobilitythanion,bycollectingelectronsandionsfromthebackgroundplasma.Theuniverseisfilledwithdustyplasmassuchasplanetaryrings,comettails,andnebulae.Also,inindustrialplasmaprocessing,particulatessuspendedinplasmaarethemajorcontaminationinsemiconductormanufacture.Studiesondustyplasmahavebeenextendedtofar-flungtopicssuchaswaves,instabilities,stro…     

Ultrasonic cavitation at liquid/solid interface in a thin Ga–In liquid layer with free surface

Cavitation in thin layer of liquid metal has potential applications in chemical reaction, soldering, extraction, and therapeutic equipment. In this work, the cavitation characteristics and acoustic pressure of a thin liquid Ga–In alloy were studied by high speed photography, numerical simulation, and bubble dynamics calculation. A self-made ultrasonic system with a TC4 sonotrode, was operated at a frequency of 20 kHz and a max output power of 1000 W during the cavitation recording experiment. The pressure field characteristic inside the thin liquid layer and its influence on the intensity, types, dimensions, and life cycles of cavitation bubbles and on the cavitation evolution process against experimental parameters were systematically studied. The results showed that acoustic pressure inside the thin liquid layer presented alternating positive and negative characteristics within 1 acoustic period (T). Cavitation bubbles nucleated and grew during the negative-pressure stage and shrank and collapsed during the positive-pressure stage. A high bubble growth speed of 16.8 m/s was obtained and evidenced by bubble dynamics calculation. The maximum absolute pressure was obtained at the bottom of the thin liquid layer and resulted in the strongest cavitation. Cavitation was divided into violent and weak stages. The violent cavitation stage lasted several hundreds of acoustic periods and had higher bubble intensity than the weak cavitation stage. Cavitation cloud preferentially appeared during the violent cavitation stage and had a life of several acoustic periods. Tiny cavitation bubbles with life cycles shorter than 1 T dominated the cavitation field. High cavitation intensities were observed at high ultrasonication power and when Q235B alloy was used because such conditions lead to high amplitudes on the substrate and further high acoustic pressure inside the liquid.     

Liquid—liquid interface in a binary mixture of associating fluids exhibiting a closed-loop immiscibility

We investigate the structure and thermodynamic properties of the liquid-liquid interface for a two-component mixture of associating fluids, exhibiting the closed-loop liquid-liquid immiscibility. In the study we apply the density functional approach and evaluate the density profiles, the ratio of unbound particles and the surface tension in order to investigate how those properties depend on the association energy.     

Electrically controlled local Frédericksz transition in a layer of a nematic liquid crystal

A local Frédericksz transition caused by electrically controlled surface anchoring in a nematic liquid crystal has been implemented owing to the displacement of surface-active ions. In the initial case, the nematic is homeotropically aligned by monomolecular layers of cetyltrimethylammonium bromide cations adsorbed on the surface of substrates. One of the substrates in a static electric field becomes free of a cation layer and specifies planar boundary conditions; as a result, a homeoplanar orientation structure is formed. The features of the dynamics of the optical response of the cell under study that are characteristic of the effect under consideration are discussed.     

Sound waves in a liquid with polydisperse vapor–gas bubbles

A mathematical model is presented for the propagation of plane, spherical, and cylindrical sound waves in a liquid containing polydisperse vapor–gas bubbles with allowance for phase transitions. A system of integro-differential equations is constructed to describe perturbed motion of a two-phase mixture, and a dispersion relation is derived. An expression for equilibrium sound velocity is obtained for a gas–liquid or vapor–liquid mixture. The theoretical results agree well with the known experimental data. The dispersion curves obtained for the phase velocity and the attenuation coefficient in a mixture of water with vapor–gas bubbles are compared for various values of vapor concentration in the bubbles and various bubble distributions in size. The evolution of pressure pulses of plane and cylindrical waves is demonstrated for different values of the initial vapor concentration in bubbles. The calculated frequency dependence of the phase sound velocity in a mixture of water with vapor bubbles is compared with experimental data.     

Hadrons as collective excitations of a superfluid coloured — Quark liquid

We investigate the excitation spectrum of a non-relativistic many-body system of coloured quarks in the presence of various Cooper-pair condensate fields. While the spin zeroqq colourless condensate within QCD is known to be responsible for the existence of pions, we argue non-relativistically that the spin — 1qq colourless condensate implies the existence of mesons, and the colour-tripletqq condensate implies the existence of baryons.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 7–June 1, 1985.     

Can surfactant be present at pinch-off of a liquid filament?

Surfactants lower surface tension and are used to facilitate breakup and spreading. How much surfactant remains where a filament of initial radius R breaks is set by the ratio of convection, which sweeps surfactant away, to diffusion, which replenishes it, or Peclet number Pe proportional, variantR. Thus, as is well known, surfactant concentration Gamma-->0 when a macroscale filament breaks. Here theory and simulation are used to investigate pinch-off of microscopic filaments. At breakup, Gamma is shown to be nonzero but uniform on a filament of negligible Pe. Since R must be finite, the zero-Pe limit is transitory and yields to a final regime. Two such regimes with distinct dynamics characterized by different scaling exponents are reported.     

Energy calibration of a BC501A liquid scintillator using a γ-γ coincidence technique

An accurate energy calibration of a BC501A liquid scintillator by means of Compton scattering of γ-rays is described.The energy resolution and the position of the Compton edge have been precisely determined using a γ-γ coincidence technique and fitting the coincidence spectrum with a Gaussian function superimposed on a quadratic polynomial for the background.The position of the Compton edge relative to the position of the maximum and the half height of the distribution in dependence on the relevant energy resolution is discussed in detail.The results indicate that the maximum energy of the recoil Compton electron does not occur at the half height distribution but at 0.90±0.05 of the maximum height in the energy range considered.The energy resolution varies from 15.6% to 8.02% for electrons in the energy region from 0.5 MeV to 3 MeV.     

Detection of a P-induced liquid ⇌ solid-phase transformation using multiple acoustic transducers in a multi-anvil apparatus

A technique for detecting and measuring phase transitions in a multi-anvil apparatus by measuring the change in travel time for a longitudinal sound wave as a function of pressure is reported. The system measures the time for pulsed ultrasonic signals to travel through a high pressure assembly with a sample in the center. Upon phase change from liquid to solid, the travel time shows an abrupt decrease due to the intrinsic increase in velocity in the sample and a reduced delay between the triggering of an amplitude threshold and the arrival of the waveform. As a proof of concept, results are shown for mercury as it undergoes pressure-induced liquid ? solid transitions at room temperature. We propose that this non-destructive technique may be valuable in situations where other in situ probing techniques cannot be readily used to provide information about changes of state and potentially to study transition kinetics at high pressures as well.     

On the effect of “Dead Water” in a stratified liquid on a solid bottom

The influence of a solid bottom on the ??dead water?? effect for gravitational and fluctuation waves (having the same dispersion law), as well as capillary waves, is calculated in a linear statement. It is found that the presence of a solid bottom aggravates the dead water effect.     

Vapor–liquid–solid growth and Sb doping of Ge nanowires from a liquid Au-Sb-Ge ternary alloy

Single-crystalline Sb-doped Ge nanowires (NWs) with excellent structural properties and uniform composition have been synthesized with high yield by vapor–liquid–solid (VLS) growth by low-temperature thermal evaporation from a mixture of Ge and Sb powders. During deposition, both the Ge and the Sb dopant became incorporated in the VLS seed nanoparticle. In situ annealing experiments during transmission electron microscopy establish that a liquid ternary Au-Sb-Ge alloy constitutes the active phase of the VLS seed drop at high temperatures, which governs the growth of the one-dimensional Ge NW and its doping by Sb.     

Spatial heterogeneity in liquid–liquid phase transition

Molecular dynamics simulations are performed to investigate the liquid–liquid phase transition(LLPT) and the spatial heterogeneity in Al–Pb monotectic alloys. The results reveal that homogeneous liquid Al–Pb alloy undergoes an LLPT,separating into Al-rich and Pb-rich domains, which is quite different from the isocompositional liquid water with a transition between low-density liquid(LDL) and high-density liquid(HDL). With spatial heterogeneity becoming large, LLPT takes place correspondingly. The relationship between the cooling rate, relaxation temperature and percentage of Al and the spatial heterogeneity is also reported. This study may throw light on the relationship between the structure heterogeneity and LLPT, which provides novel strategies to control the microstructures in the fabrication of the material with high performance.     

A molecular level study of liquid water with a flexible water model

The structural properties of water at different temperatures and pressures have been investigated by using a flexible water model and the inherent structure mechanism. The presence of 60$^\circ$ peak in the O--O--O angle distribution function and the behaviours of the hydrogen bonds in the first shell indicate that some water molecules in the second shell move toward the central molecules through the bending (not breaking) of hydrogen bonds and even become first-shell molecules of the central molecule on the basis of the O--O cutoff distance but not first-shell molecules by means of the hydrogen-bond criterion. The inherent-structure analysis of the O--O radial distribution functions at different pressures shows that the first peak is almost independent of the pressure; the position of second peak moves from 0.45 to 0.32nm as the pressure increases from $1\times 10^5$Pa to $1\times 10^9$Pa. This particularly evident pressure effect, i.e. the constant nearest-neighbours and the transformation of outer-neighbours on the basis of O--O distance, together with the results at different temperatures, gives a positive evidence for the two-state outer-neighbour mixture model: liquid water is a mixture of Ice-Ih-type-bonding and Ice-II-type bonding structures.     

Microcanonical equilibrium properties of chiral liquid crystals—a Monte Carlo study

Chiral liquid crystals have been investigated by means of a multicanonical Monte Carlo approach in order to characterize their phase behaviour by microcanonical equilibrium properties. The liquid crystals were described by three-dimensional lattice systems with intermolecular interactions given by the chiral Lebwohl-Lasher potential. Self-determined boundary conditions have been applied in order to enable the formation of chiral phases with equilibrium pitch. Selected thermodynamic properties, e.g. microcanonical entropy, temperature, heat capacity and a set of order parameters have been determined with dependence on microcanonical total energy. A cholesteric phase with temperature-induced helix inversion could be proven where the helical superstructure of the single component system studied changed its handedness through an infinite-pitch system. The thermodynamical behaviour in the microcanonical ensemble was found to be very similar to the behaviour in the canonical ensemble. The study of microcanonical equilibrium properties by means of multicanonical Monte Carlo simulations was shown to be a powerful tool for the study of the phase behaviour of model liquid crystals.