Value Of Critical Temperature Research Articles

Force Field for Calculation of the Vapor-Liquid Phase Equilibrium of trans-Decalin

Based on the TraPPE force field, previously unknown values of the parameters of the intermolecular interaction potential of trans-decalin were determined. Parametrization was carried out using experimental data on saturated vapor pressure and density at atmospheric pressure. The found parameters make it possible to adequately describe the boiling and condensation lines of trans-decalin and also predict the critical values of pressure, density, and temperature with satisfactory accuracy. Calculations of vapor-liquid phase equilibrium conditions for a binary CO2—trans-decalin mixture in supercritical conditions for CO2 were carried out. When quantitatively comparing the calculated values with experimental data, an underestimation of pressure at a temperature of 345.4 K by 30% is observed, which decreases to 5% for temperatures up to 525 K.

Fulfilling modern astrophysical observations and lattice QCD constraints based on a nonlocal NJL model with 3D form factor

AbstractIn the present work, we employ a nonlocal Nambu–Jona–Lasinio (NJL) model with a Gaussian form factor that is dependent on the spatial components of the momentum (3D‐FF). Focusing on the temperature‐baryon chemical potential plane, we investigate some aspects of the phase diagram. Initially, we propose an assumption that the range of interactions in momentum space may be modified by temperature, allowing us to obtain the critical temperature values based on lattice QCD (LQCD) predictions. Subsequently, we consider this model within a hybrid framework to examine the effects of temperature, together with neutrino trapping, in compact object configurations.

FRACTAL NANOPARTICLES OF PHASE-SEPARATING SOLID SOLUTIONS: MORPHOLOGY-DEPENDENT PHASE EQUILIBRIA IN TUNGSTEN HEAVY PSEUDO-ALLOYS

In this paper, we simulate thermodynamically the morphology-dependent phase equilibria in core-shell nanoparticles of a phase-separating solid solution using the example of W-Cr heavy alloy. The morphology of a nanoparticle is described in the framework of the fractal geometry methods. Itis shown that there are two possible heterogeneous states in a nanoparticle while the compositions of phases in both states differ from each other. The dependences of mutual solubilities of components on the temperature are obtained while the behavior of these dependences significantly differs depending on the particular state and the morphology of nanoparticle under consideration. In nanoparticles of a very complicated morphology, the phase separation itself gets suppressed and the nanoparticle remains inthe homogeneous state at the temperatures significantly below the macroscopic value of the upper critical dissolution temperature. The demonstrated regularities are explained based on three mechanisms of reducing the free energy of the system and the “competition” between them. In the final section, a method for calculating the equlibrium size distributions and average characteristics of nanoparticle ensembles is described along with a technique of measuring nanoparticle fractal dimensions based on the microscopy data.

Rheology and agglomeration behavior of semi-crystalline polyamide powders for selective laser sintering: A comparative study of PA11 and PA12 formulations

In this study, we investigated the rheological behavior of various polyamide powders as a function of temperature, shear rate, and relative humidity. Near the glass transition temperature (Tg), powders exhibited an abrupt increase in static flow threshold, indicating caking due to particle agglomeration. At higher temperatures, a transition from elastic to plastic flow was observed around 80∘C, accompanied by changes in the plateau value of the shear modulus (G0′) for different powders. In the dense flow regime, a critical temperature value dictated the transition between caking (powder’s tendency to form lumps or masses) and free-flowing behavior, with temperature promoting agglomeration and shear rate causing dispersion. The critical temperature increased with the strain rate, highlighting the delicate balance between agglomeration and dispersion. Also, it is found that Relative Humidity (RH) plays a crucial role in reducing the stress developed within the sample and counteracting the temperature effect. Additionally, the slow compaction dynamics of powders were studied, revealing an inverse logarithmic law with a characteristic relaxation time (τ) that strongly correlated with the angle of repose.

A temperature and pressure dual-responsive, stretchable, healable, adhesive, and biocompatible carboxymethyl cellulose-based conductive hydrogels for flexible wearable strain sensor

The study aimed to develop a novel temperature and pressure dual-responsive conductive hydrogel with self-healing, self-adhesive, biocompatible, and stretchable properties, for the development of multifunctional anti-counterfeiting and wearable flexible electronic materials. A conductive hydrogel based on carboxymethyl cellulose (CMC) was synthesized by simple “one pot” free radical polymerization of CMC, acrylamide (AAm) and acrylic acid (AAc). The hydrogel displayed temperature responsiveness and possessed an upper critical solution temperature (UCST) value. In addition, hydrogels also had surprising pressure responsiveness. The synthesized hydrogels were characterized by FTIR, TGA, DSC, and XRD analysis. Importantly, the obtained hydrogels exhibited exceptional mechanical properties (stress: 730 kPa, strain: 880%), fatigue resistance, stretchability, self-healing capability, self-adhesive properties, and conductivity. In addition, valuable insights were obtained into the synthesis and application of flexible anti-counterfeiting and camouflage materials by the temperature and pressure dual-responsive hydrogels. Moreover, the prepared hydrogel, with an electrically sensitive perception of external strain (GF = 2.61, response time: 80 ms), can be utilized for monitoring human movement, emotional changes, physiological signals, language, and more, rendering it suitable for novel flexible anti-counterfeiting materials and versatile wearable iontronics. Overall, this study provided novel insights into the simple and efficient synthesis and sustainable manufacturing of environmentally friendly multifunctional anti-counterfeiting materials and flexible electronic skin sensors.

Experimental investigation of saturated vapor pressure and critical parameter for R1234ze(Z) (cis-1,3,3,3-tetrafluoropropene) and R1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene)

In this study, metal-bellows variable volumetry was used to measure the saturated vapor pressures and critical parameters of R1234ze(Z) and R1336mzz(Z). The critical temperature, critical pressure, and critical density values were evaluated, and new vapor pressure correlations were formulated based on the obtained data. The low uncertainties of the measured values indicate the reliability and reproducibility of the data. The combined expanded uncertainties of critical temperature, critical pressure, and critical density were less than 50 mK, 21 kPa, and 0.6 % (k = 2, 0.95 level of confidence), respectively. 17 vapor pressure data points of R1234ze(Z) and 20 vapor pressure data points of R1336mzz(Z) were obtained at temperatures ranging from 260 K to 441 K. The combined expanded uncertainties of the temperature and saturated vapor pressure measurements were less than 20 mK and 2.2 kPa (k = 2, 0.95 level of confidence), respectively. The results provide important thermophysical data for the use of R1234ze(Z) and R1336mzz(Z) in HTHP, and can aid in the design and optimization of HTHP systems.

Effect of a Wake-Field on the Dissociation of Quarkonium in Collisional Quark–Gluon Plasma

We have studied wake effects on the dissociation of heavy quarkonia states J/ψ and Y by introducing an in-medium modification to the inter-quark potential. The wakes in the quark–gluon plasma were modeled using linear response theory using a dynamic dielectric function obtained from kinetic theory (Boltzmann equation) with a Bhatnagar–Gross–Krook (BGK) collision term. The in-medium modified potential was used to investigate the dissociation character depending on various parameters such as the velocity of quarkonium moving through the medium and the collision frequency. We have also calculated critical values of the dissociation temperature. Modifications of the dissociation energy due to wake-field effects were found.

Enhancing pinning ability by the addition of potassium niobate nanorods in YBCO superconductor

In the current study, we have investigated the effect of adding potassium niobate (KNbO3) nanorods (NRs) in YBCO superconductor to improve flux pinning properties. The KNbO3-NRs are synthesized by hydrothermal method, and KNbO3-YBCO nanocomposites are prepared by incorporating variable amounts of the NRs in YBCO matrix by solid-state reaction method. X-ray diffraction (XRD) pattern confirmed the orthorhombic phase of YBCO, KNbO3-NRs, and KNbO3-YBCO nanocomposite samples. The morphology and composition of the YBCO, KNbO3, and KNbO3-YBCO nanocomposites are studied using field emission scanning electron microscopy (FESEM) and energy-dispersive x-ray spectroscopy (EDX). Magnetic measurements of KNbO3-YBCO nanocomposites are carried out at temperatures from 15 to 65 K under an external magnetic field from -7 to + 7 T. The value of critical temperature (TC0) in xKNbO3-YBCO nanocomposites showed no significant decrease from the TC0 value obtained for YBCO, indicating that inserting a modest amount of KNbO3-NRs into the YBCO matrix does not result in substantial changes in TC0. The critical current density (JC) showed an enhancement of ∼ 3.6 times in 0.5wt%KNbO3-YBCO nanocomposite compared to YBCO. Additionally, when the concentration of KNbO3-NRs in YBCO was raised, the critical current density (JC) decreased due to the accumulation of KNbO3-NRs at the interfaces between grain boundaries. The rate of JC decay decreases as the externally applied field increases for nanocomposite samples compared to YBCO, showing an improvement in the pinning properties of nanocomposites.

Automation of the air conditioning system for aseptic rooms of pharmaceutical production

<span lang="EN-US">As modern control systems are becoming more complex, and the implemented technology more sophisticated, the importance of the different characteristics of those systems, such as reliability, availability, security, and protection, is increasing. In this article, an automation design for the air conditioning system of classified areas of the Parenteral solutions plant of the eastern pharmaceutical laboratory company of Santiago de Cuba province, Cuba, is proposed because there is a lack of optimal environmental conditions for development and production of pharmaceuticals at a large scale. The proposal is focused on the design of a supervision system and automatic control of the environmental variables that influence the drug production process. The entire algorithm for the design was developed to monitor critical and non-critical variables and control values of temperature, relative humidity, differential pressure, and air velocity according to standards established by pharmaceutical companies. The design of the automation system includes, apart from the control and supervision algorithm for operation efficiency, the necessary instrumentation.</span>

Synergistic effect of well/over-tempered hierarchical martensitic structure and carbides (M23C6 and MX) on austenite growth in 9Cr steel

To clarify the synergistic effect of well/over-tempered hierarchical martensitic structure and carbides (M23C6 and MX) on austenite growth, the austenite growth during step-heat austenitization for a selected 9Cr steel was investigated by dilatometry, multi-scale characterization and cellular automaton simulation. The austenite grain inherits the geometrical characteristics of the hierarchical martensite substructure to a significant extent through covariant and free growth. In particular, the initially heterogeneous grains with non-uniform martensitic substructure can easily produce mixed and heterogeneous grains. Step isothermal heating under AC1 can promote the evolution of martensitic structure to recrystallized ferrite and recovered equiaxed substructure, associated with coarsening of M23C6 and precipitation of MC. Apart from the recrystallized ferrite promoting the growth of equiaxed austenite grains, the recovered approximate equiaxed substructure decorated with coarse M23C6 and a large amount of MX can promote the subsequent development of fine spherical austenite grains by reducing the abnormal austenite growth and increasing the resistance to interfacial migration. The synergistic effect of the well/over tempered martensitic hierarchical structure and the carbides (M23C6, MX) is critical to the final austenite grain distribution. A window of critical temperature values for step heating austenitization to generate homogeneous austenite grain growth was established by exploiting the inheritance of the equiaxed substructure and reasonably reducing abnormal growth.

The Effect of Aliovalent Substitution on Magnetic Properties of PolyCrystalline Ca/K-1144

Among IBSC superconductors, the 1144 family ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AAE</i> Fe4As4 with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</i> =alkali metal, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AE</i> =alkaline-earth metal), has attracted considerable interest in recent years because of their propensity to form lattice defects that positively influence the flux pinning properties. Extensive research is underway to optimize this class of materials for the low-temperature high-field regime, both in the form of single crystal and polycrystalline powder. The latter is of particular interest because the 1144 material has been shown to be suitable for wire production through the easy and well-assessed Powder In Tube (PIT) process. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">In our recent experiments, it has been shown that the 1144 structure can be tailored to obtain a doped compound with a different chemical formula (<i>A</i>_x<i>AE</i>_1-x)(<i>AE</i>_y<i>A</i>_1-y)Fe₄As₄, that is characterized by unaltered critical temperature values despite the high level of substitution up to 15 at.%. In order to unveil the influence of the double substitution on the grain boundary and pinning properties of doped samples, we recently started an extensive characterization campaign whose preliminary results are presented here. Both structural and morphological properties of the compound are not affected by the simultaneous doping with 10 at.% Na and 5 at.% Ba, as revealed by XRD and SEM analyses. On the contrary, the study of magnetic properties shows that although there is no improvement in transport properties, the aliovalent substitution induces a clear change in the in-field behavior which deserves further investigations.

Critical temperature of roof trapezoidal steel sheets based on fire resistance tests

The aim of the study was to verify experimentally the proposed new values for the default critical temperature of Class 4 cross-sections subjected to bending along the major axis on the example of trapezoidal sheets used in bare or insulated roofs under fire conditions. The results of the 33 fire resistance tests of roofs according to the standard requirements of EN 1365-2 were analyzed. During these tests the steel temperature was additionally measured beyond the standard procedure. For class 4 cross-sections, a constant standard value of 350 °C is defined, regardless of the loading conditions and the load-carrying capacity exhaustion of the cross-section, while the experimentally estimated critical temperatures of the steel sheets were between 445 °C up to 755 °C e.g. higher than the standard value. The authors have shown correlations between the degree of utilisation μ0 and the critical temperature of roof trapezoidal steel sheets and no correlations between insulation layers and the value of critical temperature of roof trapezoidal steel sheets.

Influence of gauge boson mass on dynamical mass generation and chiral phase transition in thermal QED3

In this work, we quantitatively explore how a finite gauge boson mass affects dynamical mass generation and the chiral phase transition in thermal QED3. To this end, we numerically solve the Dyson–Schwinger equations by considering the contributions coming from the wave function renormalization and the spatial part of the boson propagator at first and then compute the chiral condensate and some of thermodynamic quantities. It is found that the wave function renormalization and the spatial part of the boson propagator are crucial for the numerical solutions of the dressing functions and the value of critical temperature. The behaviors of the thermodynamic quantities and the chiral condensate as a function of temperature consistently imply that the chiral phase transition is none other than a second order one. That critical temperature decreases with increasing gauge boson mass verifies that the gauge boson mass will weaken the interactions between fermions and so suppress dynamical mass generation.

Critical temperature of laterally unrestrained steel plate girders with slender section

The results of experimental research and numerical calculations pertaining to the determination of critical temperature value of steel plate girders of slender cross section subjected to lateral torsional buckling are presented in this paper. The experiments conducted in natural scale have been applied to validate the computer model prepared in the environment of ABAQUS computer code. The scope of analysis encompassed mass manufactured plate girders of the IKS type and individually designed girders. Considered components of class 4 cross section were characterized by a high total section height to flange width ratio of 3 to 5.2. Five different load levels, two steel grades and two beam loading schemes have been considered during simulations performed. Based on the results of conducted calculations a simplified method to determine the critical temperature value for the considered class of elements has been formulated. The critical temperature results obtained using this method have been compared against the results of experimental research and results determined using analytical methods. It has been shown that the proposed method assures sufficient accuracy. The influence of relative slenderness, load level and residual stresses on the forecast critical temperature value has been discussed.

Control of the Dynamic Parameters of a Flat Beam Structure by Selection of Fixing

This article proposes a method for the justified choice of the fixing method, the type of supports and their stiffness for flat beam structures of an axisymmetric cross section in order to ensure the specified values of the first frequency of natural bending vibrations and the first critical load, by taking into account the action of longitudinal forces and temperature changes. The technique is based on the well-known provisions of the theory of beam oscillations, the Euler’s theory of stability, and uses the coefficients of supports as a criterion for choosing a fixing method, which are pre-normalized to achieve comparable values. The selected fixing provides the specified value of the first natural oscillation frequency, the value of the first critical temperature, or simultaneously both conditions of working efficiency. According to the developed method, comparative calculations of a flat bar structure using the finite element method have been performed. They has shown good convergence of the results for all controlled parameters. The proposed approach can be used in the design of support fixing of flat beam structures for various purposes to ensure their dynamic behavior.

High-resistivity niobium nitride films for saturated-efficiency SMSPDs at telecom wavelengths and beyond

Incorporating a micrometer scale strip as the sensitive element in superconducting single-photon detectors can lead to significant improvements in their speed, footprint, and fabrication yield. However, the current application of microstrips has resulted in a decline in the detectors' intrinsic detection efficiency. We address this issue through the utilization of niobium nitride films with high values of resistance per square. Notably, the films used in our study possess an important characteristic of retaining high critical temperature values, which enables the devices to operate in conventional closed-cycle cryostats.

Numerical investigation of moving gel wall formation in a Y-shaped microchannel

Molecular diffusive membranes play crucial roles in the field of microfluidics for biological applications e.g., 3D cell culture and biosensors. Hydrogels provide a range of benefits such as free diffusion of small molecules, cost-effectiveness, and the ability to be produced in bulk. Among various hydrogels, Pluronic F127 can be used for cell culture purposes due to its biocompatibility and flexible characteristics regarding its environment. Aqueous solutions of Pluronic F127 shows a reversible thermo-thickening property, which can be manipulated by introduction of ions. As a result, controlled diffusion of ions into the solution of Pluronic F127 can result in a controlled gel formation. In this study, the flow of immiscible solutions of Pluronic and sodium phosphate inside a Y-shaped microchannel is simulated using the level set method, and the effects of volume flow rates and temperature on the gel formation are investigated. It is indicated that the gel wall thickness can decrease by either increasing the Pluronic volume flow rate or increasing both volume flow rates while increasing the saline volume flow rate enhances the gel wall thickness. Below a critical temperature value, no gel wall is formed, and above that, a gel wall is constructed, with a thickness that increases with temperature. This setup can be used for drug screening, where gel wall provides an environment for drug-cell interactions.Article HighlightsParallel flow of Pluronic F127 and saline solutions inside a Y-shaped microchannel results in formation of a gel wall at their interface.The numerical analysis reveals the impact of each inlet flow rate and temperature on gel wall thickness and movement.The findings indicate that the gel wall has a low but steady velocity toward the saline solution.Graphical abstract

Beyond the Planck temperature

The Planck scale physics is still unknown and the full quantum theory of gravity might reveal the mysteries of the Universe beyond the Planck scale. We consider that the maximum available temperature of a system could be higher than the Planck temperature or not. We obtain the maximum available temperature of a system with particles that obey deformed boson statistics. We evaluate the density number of particles and use the hoop conjecture to evaluate the density number of two-particles which form a blackhole as a function of temperature and deformation parameter; q. One can argue that at a certain critical value of temperature, the density number of blackholes will be dominant and this critical temperature is the maximum available temperature for the system. We show that the temperature beyond the Planck temperature is available for more deformed boson statistics while for the ordinary bosons, the maximum available temperature is . In fact, we take a look at the beyond Planck temperature in the early universe and deduce that the deformed statistics is consistent with the very high temperature at the early universe.

Temperature-sensitive polymer based nano-SiO2 composite multi-component synergistic improvement of shale stability in water-based drilling fluids

Shale instability caused by the development of nano-micron-scale fractures, pores, and bedding is always a challenge for drilling complex formations. In this work, two additives (Temperature-sensitive polymer based nano-SiO2 composite (SNAS) and poly (NVP-TAAC-AMPS) (NTA)) were synthesized. The lower critical solution temperature (LCST) value of SNAS could be controlled by adjusting the monomer ratio. As temperature-sensitive nanocomposites, SNAS has the rheological control of drilling fluid. The effects of SNAS and NTA on shale stability were tested based on analytical approaches, including shale wettability, microporous membrane fluid loss, pressure transmission rate, shale specific surface area, shale pore volume, shale strength, linear swelling percentage and shale cuttings recovery. When the temperature is higher than the LCST value, due to the transition from hydrophilicity to hydrophobicity of SNAS, it not only changes the wetting angle of shale, but also enhances the plugging effect of SNAS. The composite system could form tight plugging layer and hydrophobic region compared with single SNAS, which was more conducive to improve plugging performance of shale. Finally, the synergistic improvement mechanism of shale stability combined with SNAS and NTA were further proposed.

A BRIEF OVERVIEW OF STATIONARY TWO-DIMENSIONAL THERMOELASTIC STATE MODELS IN HOMOGENEOUS AND PIECEWISE-HOMOGENEOUS BODIES WITH CRACKS

Purpose. A two-dimensional mathematical model of the problem of thermo-elasticity for piecewise-homogeneous component plate containing a crack has been built. The stress intensity coefficients in the vertices of the crack increase affecting strength of the body significantly. This leads to the growth of a crack and, as a result, to further local destruction of a material. Therefore, such a model reflects, to some extent, the destruction mechanism of the elements of engineering structures with cracks. Methodology. Based on the method of the function of a complex variable we have studied the two-dimensional thermoelastic state for the body with crack as stress concentrators. As result, the problem of thermoelasticity was reduced to a system of two singular integral equations (SIE) of the first and second kind, a numerical solution of which was found by the method of mechanical quadratures. Findings. The two-dimensional mathematical model of the thermoelastic state has been built in order to determine the stress intensity factors at the top of the crack and inclusion. The systems of singular integral equations of the first and second kinds of the specified problem on closed (contour of inclusion) and open (crack) contours are constructed. The influence of thermophysical and mechanical properties of inclusion on the SIF sat the crack types was investigated. The dependences of the stress intensity factor which characterizes the distribution of the intensity of stresses at the vertices of a crack have been built, as well as its elastic and thermoelastic characteristics of inclusion. This would make it possible to analyze the intensity of stresses in the neighborhoods of crack vertices depending on the geometrical and mechanical factors. As a result, this allows to determine the critical values of temperature in the three-component plate containing a crack in order to prevent the growth of the crack, as well as to prevent the local destruction of the body. It was found that the appropriate selection of mechanical and thermophysical characteristics of the components of a three-component plate containing a crack can be useful to achieve an improvement in body strength in terms of the mechanics of destruction by reducing stress intensity factors at the crack’s vertices. Originality. The solutions of the new two-dimensional problem of thermoelasticity for a specified region due to the action of constant temperature as well as due to local heating by a heat flux were obtained. The studied model is the generalization of the previous models to determine the two-dimensional thermoelastic state in a piecewise homogeneous plate weakened by internal cracks. Practical value. The practical application of this model is a more complete description of the stress-strain state in piecewise homogeneous structural elements with cracks operating under temperature loads. The results of numerical calculations obtained from the solution of systems of equations and presented in the form of graphs can be used in the design of rational modes of operation of structural elements. This takes into account the possibility of preventing the growth of cracks by the appropriate selection of composite components with appropriate mechanical characteristics.