Effect Of Phase Transition Research Articles

Ultracompact hybrid stars consistent with multimessenger astrophysics

In this work, we consider the consequences of phase transition in dense QCD on the properties of compact stars and implications for the observational program in gravitational wave and x-ray astrophysics. The key underlying assumption of our modeling is a strong first-order phase transition past the point where the hadronic branch of compact stars reaches the two-solar mass limit. Our analysis predicts ultracompact stars with very small radii---in the range of 6--9 km---living on compact star sequences that are entirely consistent with the current multimessenger data. We show that sequences featuring two-solar mass hadronic stars consistent with radio-pulsar observations are also consistent with the inferences of large radii for massive neutron stars by NICER x-ray observations of neutron stars and the small radii predicted by gravitational waves analysis of the binary neutron star inspiral event GW170817 for our models that feature a strong first-order QCD phase transition.

Quasi-averaged formulation of Stefan's linear problem in drying of cylindrical beam

In the process of drying of porous materials there is a moving surface separating the dried and wet areas in the body. This surface is a phase transition, which significantly depends on the properties of the material and the temperature, which is due to the external influence of the drying agent and is a function of coordinates and time, and the movement of boundaries is a consequence of phase transitions. The paper presents the properties of the material, namely: heat capacity, density, thermal conductivity coefficients to be the functions of the porosity of the material, densities and heat capacities of body components.

Thermal resummation and phase transitions

The consequences of phase transitions in the early universe are becoming testable in a variety of manners, from colliders physics to gravitational wave astronomy. In particular one phase transition we know of, the electroweak phase transition (EWPT), could potentially be first order in BSM scenarios and testable in the near future. If confirmed this could provide a mechanism for baryogenesis, which is one of the most important outstanding questions in physics. To reliably make predictions it is necessary to have full control of the finite temperature scalar potentials. However, as we show the standard methods used in BSM physics to improve phase transition calculations, resumming hard thermal loops, introduces significant errors into the scalar potential. In addition, the standard methods make it impossible to match theories to an EFT description reliably. In this paper we define a thermal resummation procedure based on partial dressing (PD) for general BSM calculations of phase transitions beyond the high-temperature approximation. Additionally, we introduce the modified optimized partial dressing (OPD) procedure, which is numerically nearly as efficient as old incorrect methods, while yielding identical results to the full PD calculation. This can be easily applied to future BSM studies of phase transitions in the early universe. As an example, we show that in unmixed singlet scalar extensions of the SM, the (O)PD calculations make new phenomenological predictions compared to previous analyses. An important future application is the study of EFTs at finite temperature.

Kinetic features of the new phase nucleation in the electric field in some lead-containing relaxors

The kinetics and dynamics of the new phase nucleation in an external electric field E in ferroelectric relaxors Pb1/2Nb1/2O3–PbMg1/3Nb2/3O3–x (x = 25 and 32%) and PbMg1/3Nb2/3O3–29PbTiO3 have been investigated. The joint measurements of optical transmittance at different wavelengths as well as the sound speed and attenuation at different frequencies have been carried out at room temperature. The analysis of the character of the changes of the optical and acoustic properties in different electric fields has been performed with the aim of identifying the mechanisms of such changes under phase transition conditions. The reduction of optical transmission with time is associated only with the size change of nanoregions in the process of phase transition. The observed acoustic anomalies are the consequence of phase transition and conditioned by the lattice increased rigidity, caused by a large piezoelectric effect in the ferroelectric phase.

Dy3+ Occupancy in Zirconia Lattice Affects Tetragonal to Cubic Phase Transitions in Zirconia Toughened Alumina Systems

Current research on zirconia toughened alumina (ZTA) systems employed in total hip joint replacement applications is focused on the usage of alternative stabilizers to improve their properties. Herein, a wide range of dysprosium (Dy3+) additions to ZTA systems have been formed through an in situ method. Dy3+ induced significant structural changes in ZrO2 rather than the α-Al2O3 component of the composite. Dy3+ tends to occupy along the a = b-axis of the ZrO2 lattice to stabilize tetragonal zirconia (t-ZrO2), whereas its enhanced accumulation directed the formation of cubic zirconia (c-ZrO2). As a consequence of phase transition, a different behavior in the emission characteristics was also noticed. However, t- → c-ZrO2 phase transition was not found to affect the paramagnetic behavior of Dy3+ added ZTA systems. The structural stability of the Dy3+ added ZTA systems was preserved until 1500 °C, and moreover it was also determined that optimum Dy3+ content is essential for enhanced mechanical stability of t...

Phase Space and Dynamical Fluctuations of Kaon-to-Pion Ratios

Abstract The dynamical fluctuations of kaon-to-pion ratios have been studied over a wide range of center-of-mass energies √s. On the basis of changing phase space volume which apparently is the consequence of phase transition from hadrons to quark-gluon plasma at large √s, the single-particle distribution function f is assumed to be rather modified. Varying f and phase space volume are implemented in the grand-canonical partition function, especially at large √s, so that the hadron resonance gas model, when taking into account the experimental acceptance and quark phase space occupation factor, turns to be able to reproduce the dynamical fluctuations of kaon-to-pion ratios over the entire range of √s.

Phase transition from quark-meson coupling hyperonic matter to deconfined quark matter

We investigate the possibility and consequences of phase transitions from an equation of state (EOS) describing nucleons and hyperons interacting via mean fields of $\ensuremath{\sigma}$, $\ensuremath{\omega}$, and $\ensuremath{\rho}$ mesons in the recently improved quark-meson coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag. The transition to a mixed phase of baryons and deconfined quarks, and subsequently to a pure deconfined quark phase, is described using the method of Glendenning. The overall EOS for the three phases is calculated for various scenarios and used to calculate stellar solutions using the Tolman-Oppenheimer-Volkoff equations. The results are compared with recent experimental data, and the validity of each case is discussed with consequences for determining the species content of the interior of neutron stars.

Modelling the temperature dependence of oxidation rate in water-in-oil emulsions stored at sub-zero temperatures

The aim of the present research was to model the temperature dependence of lipid oxidation rate in water-in-oil emulsions stored at sub-zero temperatures. In fact, the application of the well-known Arrhenius equation resulted precluded in such conditions. To this purpose, the physical state and the oxidation rate of sunflower oil–water emulsions were evaluated from −30 to 60 °C. Results indicate that the rate of oxidation could be considered as a resultant of a complex interplay between the physicochemical changes occurring in the hydrophilic and hydrophobic phases as a consequence of phase transitions. By taking into account the changes in oil viscosity and in the reactant concentration in both lipid and water phase it was possible to set up a mathematical model able to describe the temperature dependence of oxidation rate in multiphase systems in the entire range of temperatures considered.

Influence of Crystallization on the Oxidative Stability of Extra Virgin Olive Oil

The aim of this study was to evaluate the influence of the extra virgin olive oil (EVOO) physical state on the kinetics of oxidative reactions. To this purpose, EVOO was stored at increasing temperatures from 3 to 60 degrees C and the oxidation was followed by measuring both primary and secondary oxidation products. Results highlighted that crystallization plays an important role in determining EVOO stability. Below the melting point, the oxidation rate was found to be higher than that expected on the basis of the Arrhenius equation. The observed deviation from the Arrhenius equation was attributed to the physicochemical changes occurring as a consequence of phase transitions. In particular, the increase in unsaturated triacylglycerol concentration and the decrease of polyphenol content in the liquid phase surrounding fat crystals were indicated as the main factors causing the deviation. By taking into account these changes it was possible to describe the temperature dependence of the oxidation rate in the entire range of temperatures considered. This model appears to be promising in the challenge to find mathematical models able to predict the stability and, hence, the shelf life of lipid-containing foods.

Temperature studies ofKH2PO4:Mncrystals using x-ray diffraction and polarized Raman scattering

$\mathrm{K}{\mathrm{H}}_{2}\mathrm{P}{\mathrm{O}}_{4}$ (KDP) crystals doped with Mn ions were studied by an x-ray multiple diffraction technique using synchrotron radiation at room temperature. Asymmetric peaks were observed for both undoped and doped crystals, a characteristic of perfect crystals. X-ray powder diffraction at room temperature and analysis by Rietveld refinement were also performed, showing that doped KDP has the same tetragonal structure as undoped KDP, but with contraction of the lattice parameter for [100], [010], and [001] directions. The polarized Raman spectra of KDP and KDP:Mn were obtained for temperatures in the range $10--300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Some of the features observed in the spectra were interpreted as consequences of phase transitions. Although group theory analysis shows that both doped and undoped crystals have the same symmetry at room temperature, at low temperature they have different symmetries: a previously reported phase transition for KDP at $60\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ was not observed for KDP:Mn.

Effect of mineral phase transitions on sedimentary basin subsidence and uplift

Metamorphic phase transitions influence rock density, which is a major parameter affecting lithosphere dynamics and basin subsidence. To assess the importance of these effects, we have computed realistic density models for a range of crustal and mantle mineralogies from thermodynamic data by free-energy minimization. These density distributions are incorporated into one- and two-dimensional kinematic models of basin subsidence. The results demonstrate that, compared to models in which density is solely temperature dependent, phase transitions have the effect of increasing post-rift subsidence while decreasing syn-rift subsidence. Discrepancies between our model results and those obtained with the conventional uniform stretching models can be up to 95% for reasonable parameter choices. The models also predict up to 1 km of syn-rift uplift as a consequence of phase transitions. Mantle phase transitions, in particular the spinel–garnet–plagioclase–lherzolite transitions are responsible for the most significant effects on subsidence. Differences in mantle composition are shown to be a second-order effect. Parameterized density models are derived for crustal and mantle rocks, which reproduce the main effects of the phase transitions on subsidence.

Are solidified fillings of mesopores basically bulk-like except for the geometric confinement?

A short review of our thermodynamic and structural work on Ar, N(2), CO, O(2), and the n-alkane C(19)H(40) in mesoporous glasses is presented. The experimental information comes from X-ray diffraction, vapour pressure isotherms, optical transmission, heat capacity, and dielectric measurements. The filling in the pore centre formed by capillary condensation is distinguished from the adsorbed layers on the pore walls and is compared to the bulk state. Special attention is paid to metastable states and to the rearrangement of partial fillings that show up as a consequence of phase transitions.

Density changes upon crystallization of Ge2Sb2.04Te4.74 films

The density of sputtered Ge2Sb2.04Te4.74 thin films upon annealing has been precisely determined by x-ray reflection and compared to the values determined from x-ray diffraction (XRD) data. The film density increases in two steps around 130 and 280 °C upon annealing up to 400 °C. These increases are consequences of phase transitions from amorphous to NaCl type and from NaCl type to hexagonal structure, respectively, as revealed by XRD. Average density values of 5.87±0.02, 6.27±0.02, and 6.39±0.02 g/cm3 were measured for the amorphous, NaCl-type, and hexagonal phases, respectively. This corresponds to density changes upon crystallization of 6.8±0.2% and 8.8±0.2% for NaCl-type and hexagonal phases, respectively. The accompanying film thickness reductions were determined to be 6.5±0.2% and 8.2±0.2%, which compares very well with the density changes. The corresponding XRD values are determined to be 6.43–6.48 and 6.48 g/cm3 for NaCl-type and the hexagonal phases, respectively. This shows that nearly void-free films are formed.

Isotope effects and the manifestation of 2D phase transitions in the kinetics of low-temperature (down to 5 K) hydrogen adsorption

The adsorption–desorption characteristics of hydrogen isotopes on the (110) surfaces of W and Mo are investigated at a temperature Ts∼5 K. It is found that the characteristics for hydrogen and deuterium are very different. Isothermal desorption from W(110) at Ts∼5 K is observed in the case of H2, while that of D2 is practically absent. The desorption of H2 is suppressed as the flux of molecules to the surface increases; this, in the opinion of the authors, is a consequence of phase transition from a 2D gas to a 2D condensate. The initial sticking probability of H2 on W(110) depends strongly on the flux, while that of D2 is nearly independent of flux; in the H2 case this is explained by the formation of nuclei of the 2D condensed phase during the lifetime of the molecule in the precursor state. In the case of H2 adsorption on Mo(110) a sharp and deep minimum is observed in the dependence of the sticking probability on the coverage, which is absent in the case of D2. These isotope effects are explained by the deeper position of the levels of the zero-point vibrations of the heavier molecule D2.

POSSIBLE DYNAMICAL ORIGINS OF INTERMITTENCY IN HIGH ENERGY COLLISIONS

This is a brief review of the dynamical origins of intermittency. For elementary processes involving leptons and hadrons, we discuss toy models, perturbative QCD, Monte-Carlo and other models. For complex processes involving nuclear collisions we review theoretical ideas on hadronic fluctuations as consequences of phase transition.

Verträglichkeit von kautschuken ein altes und ein aktuelles problem

AbstractThe utilization of rubber mixtures is to achieve a desired combination of properties and performance spectrum of elastomers is nowadays of a considerable technological and economical importance. The successful implementation of this concept requires the knowledge of the factors governing both the phase behaviour of rubber blends and the morphology of phase separated blends. Thermodynamic theories referring to miscibility and phase separation of polymers are briefly reviewed, with a specific focus on nonpolar polymers with high chain flexibility. It can be shown on the simple lattice that this theory works qualitatively for these systems. Reliable predictions are questionable due to the lack of equation of state parameters for the polymers of interest and temperature and concentration dependence of the interaction parameter χ.Concerning the morphology of phase separated rubber blends the main influences governing the structure of the entire system (i) the interfacial tension, (ii) the viscosity of the matrix (iii) and the shear stress are discussed in more detail. It has been pointed out that for technological usability a better knowledge about the interdiffusion of polymers and the properties of the interphase, built in this would be not only of scientific interest but also beneficial for high performance elastomer blends. It would also be useful to know more about the dispersion of polymers at short mixing times and elevated temperatures. Because it has been considered until recently that polymer miscibility occurs only if strong specific segmental interaction are involved, emphasis was dedicated to oligomer/rubber‐ and rubber/rubber‐systems which exhibit miscibility and phase transitions through a convex coexistence curve into a homogeneous region. Consequences of phase transitions at high mixing temperatures for specific tire applications are suggested.

Some consequences of phase transitions in neutron stars

Some consequences of phase transitions in neutron stars