Radius Of Nucleus Research Articles

Investigation of Recrystallization Kinetics in 1050 Al Alloy by Experimental Evidence and Modeling Approach.

The recrystallization (RX) kinetics of commercially pure Al alloy is studied under the scope of annealing temperature, time, and degree of deformation. To examine the distribution of recrystallization, Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory is employed, where the path of microstructural transformation from the deformed state to the fully recovered one is studied as a function of the volume fraction of recrystallized grains (XV) and annealing time. The drop in hardness is recorded for the samples at various stages of annealing with a corresponding decrease in stored energy as the annealing time increases. The stored energy obtained from the hardness results and Orientation Imaging Microscopy (OIM)-based method is found to be in good agreement with each other, proving the efficiency of both techniques. To determine the volume fraction of the recrystallized microstructure, data obtained from Vickers hardness measurements are used. Various parameters associated with recrystallization statistics such as the critical radius of nuclei, the incubation period, and the mobility of High-Angle Grain Boundaries (HAGB) were derived from the experimental evidence. The experimental data also suggest a sharp drop in the velocity of HAGB as the RX transformation process approaches its completion, which is found to be a direct result of a drop in stored energy. A softening window between 42 s and 55 s is identified for our experimental data where the hardness, stored energy, and velocity of HAGB drops very sharply, and the maximum fraction of deformed grains is expected to be converted to the recrystallized ones. Along with experimental observations, an analytical model was developed, which helps to approximate the kinetics of RX and corresponding parameters for various annealing temperatures and strains while revealing the characteristic feature of Avrami exponent n. Both experimental evidence and model data reveal a very strong dependency of recrystallization behavior on the stored energy.

The Influence of Solvent Selection upon the Crystallizability and Nucleation Kinetics of Tolfenamic Acid Form II.

The influence of the solution environment on the solution thermodynamics, crystallizability, and nucleation of tolfenamic acid (TFA) in five different solvents (isopropanol, ethanol, methanol, toluene, and acetonitrile) is examined using an integrated workflow encompassing both experimental studies and intermolecular modeling. The solubility of TFA in isopropanol is found to be the highest, consistent with the strongest solvent-solute interactions, and a concomitantly higher than ideal solubility. The crystallizability is found to be highly dependent on the solvent type with the overall order being isopropanol < ethanol < methanol < toluene < acetonitrile with the widest solution metastable zone width in isopropanol (24.49 to 47.41 °C) and the narrowest in acetonitrile (8.23 to 16.17 °C). Nucleation is found to occur via progressive mechanism in all the solvents studied. The calculated nucleation parameters reveal a considerably higher interfacial tension and larger critical nucleus radius in the isopropanol solutions, indicating the higher energy barrier hindering nucleation and hence lowering the nucleation rate. This is supported by diffusion coefficient measurements which are lowest in isopropanol, highlighting the lower molecular diffusion in the bulk of solution compared to the other solutions. The TFA concentration and critical supersaturation at the crystallization onset is found to be directly correlated with TFA/isopropanol solutions having the highest values of solubility and critical supersaturation. Intermolecular modeling of solute-solvent interactions supports the experimental observations of the solubility and crystallizability, highlighting the importance of understanding solvent selection and solution state structure at the molecular level in directing the solubility, solute mass transfer, crystallizability, and nucleation kinetics.

Nucleation kinetics of reactive crystallization of ammonium di-uranate

ABSTRACT The reactive crystallisation of ammonium di-uranate (NH4U2O7) from uranyl nitrate (UO2 (NO3)2) and ammonia (NH3) is a key process in the nuclear fuel cycle towards uranium-bearing fuel preparation. However, the process kinetics and mechanism remain poorly understood and the modelling of the reactive crystallisation of NH4U2O7(ADU) is not available. Hence, this work aims to determine the kinetics and mechanisms of the nucleation and growth of ADU through induction time measurements by comparing sonochemical and conventional precipitation methods. Induction was measured as functions of initial supersaturation starting from S = 1.07 to S = 1.875 and in a temperature range of 30 °C to 80 °C. The solubility data of ADU were also found experimentally. The trends in the experimental data suggest that two nucleation mechanisms co-exist: heterogeneous and homogeneous nucleation at low and high supersaturations respectively. Due to acoustic cavitation of the ultrasound prompting micromixing, the induction time is markedly reduced in the sonochemical route owing to the reduction of the energy barrier for nucleation. The induction time data were also analysed to calculate the interfacial energy (γ) and other parameters including the radius of the critical nucleus (r*), critical free energy of the nucleus (ΔG*) and nucleation rate (J). Determination of nucleation kinetics gives us insights into the fundamentals of the ADU crystallisation process for control and optimisation. Highlights: Nucleation kinetics of the reactive crystallisation of ADU was studied through classical nucleation theory Induction time data with supersaturation are interpreted by classical nucleation theory and different crystallisation kinetic parameters were determined Homogeneous and heterogeneous nucleation was determined from the correlation A comparison of sonochemical and conventional precipitation shows that in the sonochemical route, the nucleation happens at lower supersaturation with lower induction time because of much lower activation energy requirement All the model data gives us an insight into the crystallisation kinetics to optimise and control the crystallisation process of ADU

2023 Recovery Observations and Characterization of the Active Centaur P/2010 TO20 (LINEAR-Grauer)

We report the recovery of the Centaur P/2010 TO20 (LINEAR-Grauer) on CCD imaging data from three separate dates in 2023 April, May, and June from the 8.1 m Gemini South Telescope, representing its first known detections since 2012. The recovery observations display a compact coma and tail, consistent with ongoing activity after its recent 2022 November 27 perihelion passage. We estimate a nucleus radius upper-limit of r n ≤ 2.7 km. Due to the current uncertainty inherent in the nucleus’ true size, we report a plausible range for the dust production of 2.7 cm ≤ Af ρ ≤ 14.5 cm after subtraction of an assumed nucleus flux based on radii of 2.7 km and 0.5 km, respectively. P/2010 TO20 experienced a recent and well-defined orbital change and associated change in thermal environment, making it an exciting target through which to study Centaur activity drivers and their evolution as their orbits change in real-time.

K teorii nukleatsii ionnykh soley iz vodnykh rastvorov

The theory of nucleation of ionic salts from aqueous solution is critically analyzed and further developed in two limiting cases of sparingly and highly soluble strong electrolytes. In the case of sparingly soluble colloids with a relatively large screening length (compared to the radius of the critical nucleus), the classical nucleation theory is modified by taking into account the influence of the critical nucleus charge on the nucleation rate, which was disregarded in earlier models. In the opposite limit of highly soluble colloids which are characterized by a relatively small screening length, the influence of the critical nucleus charge on the nucleation rate can be neglected with good accuracy. However, the discrepancy with earlier models, mainly related to the value of the pre-exponential factor, can reach several orders of magnitude.

Large‐scale synthesis of CuS nanoparticles for photothermal materials using high‐concentration Cu complex ion precursor

AbstractCopper sulfide (CuS), a copper‐deficient p‐type semiconductor material, has been widely utilized due to its unique optical properties, low toxicity, and cost‐effectiveness. Although many studies have been conducted on synthesizing CuS nanoparticles, harsh synthetic conditions and low yield must be solved. This study presents a new methodology that can synthesize CuS nanoparticles in large quantities at room temperature and pressure using high‐concentration Cu complex ion precursors. This methodology is based on the theory that the critical nucleus radius and the critical nucleation free energy decrease as the concentration of the precursor increases to synthesize a large number of nanoparticles by applying low energy. In addition, it is possible to minimize the aggregation of nanoparticles, which is a problem of nanoparticles synthesized at a high precursor concentration through complex ions in the solution. We synthesized nanoparticles by controlling the precursor concentration from 0.1 to 2.5 M to confirm the effect of the precursor concentration on the size, shape, and yield of nanoparticles. As the precursor concentration increased, the particle size decreased, and the yield improved. The CuS nanoparticles synthesized at the highest concentration had a size of about 17 nm without a strong agglomeration and a yield of about 213.9 g/L. Furthermore, the nanoparticles showed excellent photothermal performance due to their high near‐infrared absorption. When about 0.1 g of the nanoparticles were irradiated with a Xenon lamp and an 808 nm laser, the maximum temperatures and rising rates were 53.7°C and 172.1°C and 13.8°C/mg and 33°C/mg, respectively. The excellent photothermal properties of CuS nanoparticles suggest the potential of this material for various applications.

A systematic analysis of the particle irradiation data ensemble in the key of the microdosimetric kinetic model: Should clonogenic data be used for clinical relative biological effectiveness?

PurposeTo perform a systematic analysis of the Particle Irradiation Data Ensemble (PIDE) database for clonogenic survival assays in the context of the Microdosimetric Kinetic Model (MKM). Methods and materialOur study used data from the PIDE database containing data on various cell lines and radiation types. Two main parameters of the MKM were determined experiment-wise: the domain radius, which accounts for the increase of the linear parameter as a function of LET or lineal energy, and the nucleus radius, which accounts for the overkilling effect at LET high enough. We used experiments with LET less and more than 75 keV/μm to determine domain and nucleus radius, respectively. Experiments with cells in asynchronous phase of the cell cycle and monoenergetic beams were considered, and data from 294 out of 461 available experiments with protons, alpha, and carbon beams were used. ResultsDomain and nucleus radii were determined for 32 cell lines as the median among cell-specific experiments after filtering experiments using protons, α-particles, and carbon ions, including 28 human cells and 12 rodent cells. The median values found for domain radii were 380 nm for normal human cells, 390 nm for tumor human cells, 295 nm for normal rodent cells, and 525 nm for tumor rodent cells (only one experiment with rodent tumor cells) with large variability across cell lines and across experiments on each cell line. ConclusionsLarge inter-experiment variabilities were found for the same cell lines, based on enormous experimental uncertainties and different experimental conditions. Our analysis raises questions about how convenient is to use clonogenic data to feed RBE models to be utilized in the clinical practice in particle therapy.

Mechanism study of synergistic effect of organic and inorganic foulants in membrane distillation

In this paper, we investigated the mechanism of membrane fouling during the membrane distillation (MD) process by using humic acid (HA) and calcium carbonate (CaCO3) as the model organic and inorganic foulants respectively. The aggregation induced crystallization theory was introduced to analyze the fouling process. Field emission scanning electron microscopy (FESEM) images and X-ray photoelectron spectroscopy (XPS) were used to examine the morphology and variation of foulants on membrane surfaces that treated different feeds at different concentration factors. The interface free energies of the membranes surfaces were calculated based on contact angles and surface tensions between the testing solutions and the membrane surfaces. The results indicated that the aggregations of HA onto the hydrophobic polyvinylidene fluoride (PVDF) membrane surface altered membrane surface properties, which reduced critical nucleus radius (R⁎) and facilitated the heterogeneous nucleation of CaCO3. Furthermore, the presence of calcium ion enhanced the aggregation of HA, which further promoted the crystallization of CaCO3.

OzDES Reverberation Mapping Programme: Mg ii lags and R−L relation

ABSTRACT The correlation between the broad line region radius and continuum luminosity (R–L relation) of active galactic nuclei (AGNs) is critical for single-epoch mass estimates of supermassive black holes (SMBHs). At z ∼ 1–2, where AGN activity peaks, the R–L relation is constrained by the reverberation mapping (RM) lags of the Mg ii line. We present 25 Mg ii lags from the Australian Dark Energy Survey RM project based on 6 yr of monitoring. We define quantitative criteria to select good lag measurements and verify their reliability with simulations based on both the damped random walk stochastic model and the rescaled, resampled versions of the observed light curves of local, well-measured AGN. Our sample significantly increases the number of Mg ii lags and extends the R–L relation to higher redshifts and luminosities. The relative iron line strength $\mathcal {R}_{\rm Fe}$ has little impact on the R–L relation. The best-fitting Mg iiR–L relation has a slope α = 0.39 ± 0.08 with an intrinsic scatter $\sigma _{\rm rl} = 0.15^{+0.03}_{-0.02}$ . The slope is consistent with previous measurements and shallower than the H β R–L relation. The intrinsic scatter of the new R–L relation is substantially smaller than previous studies and comparable to the intrinsic scatter of the H β R–L relation. Our new R–L relation will enable more precise single-epoch mass estimates and SMBH demographic studies at cosmic noon.

Cluster model for calculation binding energy of 222,224Ra

The nucleus can be considered a relativistic system, In particular, we focus on heavy nuclei with zero spin and utilize the relativistic core-cluster model to investigate their structure properties. A zero-spin nucleus is assumed to consist of a core and a cluster, core and cluster spins are zero. We will solve the Klein–Gordon equation, which is a relativistic equation optimized for studying zero-spin systems, with the new phenomenological potential. Then, we will calculate the binding energy and charge radius of the zero-spin heavy nuclei by employing the wave function obtained from the Klein–Gordon equation.

A new cavitation model for simulating steady and unsteady cavitating flows

Cavitation is a widespread hydrodynamic phenomenon. Accurate prediction of cavitating flow is beneficial to the design and maintenance of the hydrodynamic machinery. A new cavitation model reducing the number of parameters needed to obtain satisfactory results is presented and validated. Based on the multiphase flow equation, the mass transfer due to cavitation is expressed as a source term in the gas-phase continuity equation. The mass transfer rate is derived from the assumption that the number of cavitation nuclei per unit volume in the mixture varies linearly with the vapor volume fraction during the evaporation stage. The mass transfer rate also incorporates the simplified Rayleigh–Plesset equation and the critical radius of cavitation nuclei. The new cavitation model considers the influence of non-condensable gas and the molar density of non-condensable gas is the only physical parameter that must be specified. The cavitating flow over a hydrofoil, cavitating flow in a sharp-edged orifice, and the unsteady cavitating flow in a venturi tube were predicted to verify the validity of the new cavitation model. The simulation results of the new model are in good agreement with the experimental results. The new cavitation model predicts cavitation regions and periodic unsteady cavitating flows.

Re-Distribution of the Regions of 100 Comets Using a Statistical Method

In this study, the comets have distributions regarding their heliocentric distances where they appear in two regions, Kuiper belt (short period) and Oort cloud (long period). Details here give new information about the entire regions of these comets; the research shows that 54% of comets are nearby asteroid belt, but only 11% are in Kuiper belts and 35 % are from Oort cloud. The research focuses on comets with a nucleus's radius larger than 1 km. The comets with a nuclear radius of 1-10 km have high percentage 51%. From the results, the maximum comets' radius is found in comet 29P/Schwassmann -Wachmann as roughly 87 km, and also in comet C/2018 N2 (ASASSN) which has radius 88 km. All comets, that have been distributed concerning heliocentric, depend on statistical results to divide new comets' regions versus their radiuses. The results reveal new details of comets' distances from the sun. The distances of 100 comets are shown in Figure (2). The results show that there is a third comets' region: region (A) found between Mars and Saturn and between Oort cloud and Kuiper belt. There is one comet like(C/2019 L3 (ATLAS)) that is farther than Alpha Centauri star. Therefore, the comet is restricted by a couple of gravity systems.

A possible selection criterion of the target of Comet Interceptor mission

The ESA mission Comet Interceptor will target an Oort Cloud or interstellar comet during its first approach to the heliocentric distance rh≈1 au, and has been designed to handle the dust loss rate of 1P/Halley as an upper limit of activity level. In the framework of the adopted model of pebble-made nuclei, any extrapolation at rh≈1 au of the dust loss rate observed beyond Jupiter is impossible, because the dust loss rate at rh>3.8 au depends on the nucleus surface area, Ap, composed of water-poor pebbles, whereas at rh<3.8 au the dust loss rate depends on the nucleus surface area, Ar, composed of water-rich pebbles. Pebble-made nuclei are characterized by all possible values Ap/Ar⩾12. The water-driven activity model of pebble-made nuclei has been applied to comets 1P/Halley and C/1995O1 Hale-Bopp. We find that all comets with a nucleus radius smaller than 3.2-0.9+2.3 km will be characterized by a dust loss rate lower than 1P/Halley at rh≈1 au, i.e. will be safe for Comet Interceptor, whichever their ratio Ap/Ar⩾12 will be. We also find that the lower limit of the average refractory-to-water–ice mass ratio of all comets is 3.4.

TNO or Comet? The Search for Activity and Characterization of Distant Object 418993 (2009 MS9)

The perihelion of the trans-Neptunian object (TNO) 2009 MS9 brings it close to the distance where some long-period comets are seen to become active. Knowing this, and the fact that this object appears to brighten in excess of its predicted nucleus brightness, suggests that 2009 MS9 has a delayed onset of activity brought on by the sublimation of a species more volatile than water. In this paper, we characterize 2009 MS9's physical properties and investigate potential outgassing through composite images, sublimation models, and measurements of spectral reflectivity. We find that deep composite images of the object at various epochs along its orbit show no evidence of dust yet place sensitive limits to the dust production. We estimate the nucleus radius to be 11.5 ± 3.5 km using thermal IR modeling from NEOWISE data and use this and data pre-perihelion to estimate a geometric albedo of 0.25. We compare a CO sublimation activity model to its post-perihelion heliocentric light curve and find that these data support an active fractional area of 5 × 10−6 assuming 2 μm–sized grains and other typical comet parameters. The spectral reflectivity of the surface materials obtained with the Gemini Observatory and CFHT at different epochs shows a reddening spectral slope. We compare the physical properties of 2009 MS9 to both TNO and comet populations and speculate that 2009 MS9's reddening may be due to the buildup of a dust mantle on the surface and could be an explanation of why TNOs exhibit a color bimodality.

Skyrme-Hartree-Fock on Deformed Nucleus for the Island of Inversion Case

The Island of Inversion is a state where the energy levels are not in a standard order. As a result, it will affect the calculation of several other physical quantities. One of those affected is the calculation of the radius of the nuclear charge. For this reason, this paper will present the analysis of the radius of the nucleus charge using the Skrme Hartree Fock method on a deformed nucleus. Through deformation effects, especially the quadruple effect, it is expected that the radius of the nuclear charge will increase. In this paper, we will present the calculation of the nucleus radius using the SHF deformed nucleus method and compare it with the SHF for the ground state nucleus. The calculation results show that this method can adequately handle the island of the inversion effect.

Nonisothermal crystallization kinetics of potassium chloride produced by stirred crystallization

The elucidation of the crystal nucleation and growth process can help control crystal size and quality. Here,the classical theory of primary nucleation was first used to study the homogeneous and heterogeneous nucleation mechanism of potassium chloride (KCl) crystallization. The growth kinetics in the presence of seed in KCl was then investigated. To understand the nucleation mechanism of KCl, the induction period of KCl was analyzed using classical nucleation theory to calculate the interfacial tension (γ) and various nucleation parameters, including the radius of the critical nucleus (r*), the critical free energy of the nucleus (ΔG*), and the molecular number of the critical nucleus (i*). The results showed a homogeneous nucleation mechanism at high supersaturation ratios (≥1.10) and a heterogeneous nucleation mechanism at low supersaturation ratios (<1.08). Meanwhile, the KCl crystal exhibited a continuous growth mechanism as inferred by the surface entropy factor (f) value. The SEM data demonstrated that the increase in crystallization temperature and supersaturation ratio could increase the average crystal size. The particle size-independent growth model is suitable for the growth process according to the relationship between crystal particle number density and particle size. In addition, the crystal nucleation and growth rates in stirred crystallization were calculated using the population balance equation, and then various kinetic parameters were estimated. The estimated parameters suggested an increase in growth with an increase in supersaturation ratio and stirring rate. Meanwhile, the impact of each parameter in the nucleation rate equation showed that the degree of influence is suspension density, supersaturation ratio, and finally, stirring rate.

Heterogeneous nucleation on the conic surface substrate

Nucleation is an essential step in the crystallization process of materials and determines their properties. In industrial production, nucleating agents are often added to melt or solution systems to control the formation process of the nucleus. In this paper, we investigate the problem of heterogeneous nucleation on conical surface substrates. Within the classical nucleation theory framework, a shape factor is introduced to measure the nucleation ability on a conical surface substrate. We found that the radius of the spherical nucleus is independent of the shape of the conic surface. As the eccentricity of the conic curve increases and the smaller the shape factor for nucleation, the easier it is to nucleate. In particular, there are special cases of the non-spherical nuclei on hyperboloid, paraboloid, and ellipsoidal substrates. We have determined the relationship that the size coefficient, wetting angle, and eccentricity satisfy when spherical nuclei are formed on a conical surface substrate. Therefore, the research results of this paper provide a theoretical model for selecting nucleating agents.

Hadron and light nucleus radii from electron scattering* *Supported by the National Natural Science Foundation of China (12135007); Natural Science Foundation of Jiangsu Province (BK20220122) and STRONG-2020 "The strong interaction at the frontier of knowledge: fundamental research and applications" which received funding from the European Union's Horizon 2020 research and innovation programme (824093)

Conceptually, radii are amongst the simplest Poincaré-invariant properties that can be associated with hadrons and light nuclei. Accurate values of these quantities are necessary so that one may judge the character of putative solutions to the strong interaction problem within the Standard Model. However, limiting their ability to serve in this role, recent measurements and new analyses of older data have revealed uncertainties and imprecisions in the radii of the proton, pion, kaon, and deuteron. In the context of radius measurement using electron+hadron elastic scattering, the past decade has shown that reliable extraction requires minimisation of bias associated with practitioner-dependent choices of data fitting functions. Different answers to that challenge have been offered; and this perspective describes the statistical Schlessinger point method (SPM), in unifying applications to proton, pion, kaon, and deuteron radii. Grounded in analytic function theory, independent of assumptions about underlying dynamics, free from practitioner-induced bias, and applicable in the same form to diverse systems and observables, the SPM returns an objective expression of the information contained in any data under consideration. Its robust nature and versatility make it suitable for use in many branches of experiment and theory.

Relativistic correction of the Coulomb interaction in the local density approximation for energies and radii in doubly-magic nuclei

Abstract Effects of the relativistic correction of the Coulomb interaction on doubly-magic nuclei are discussed with Skyrme Hartree–Fock calculations. The relativistic correction is treated by using the local density approximation. It is found that the correction to the total energy is about $2.4 \, \mathrm{MeV}$ for ${}^{208}_{}\mathrm{Pb}$, while the proton and neutron radii do not change significantly. This difference is larger than the difference of the Coulomb exchange (Fock) energy calculated with the local density (Hartree–Fock–Slater) approximation and that with the exact treatment and the neutron finite-size effect. Effects of the correction are also compared to the correction due to the vacuum polarization. It is shown that the two contributions to the total energy are comparable in light nuclei, but the latter dominates in heavy nuclei, while the contribution of the relativistic correction to the total energy is non-negligible compared to the target accuracy of the DFT calculation.

Theory of dynamical cavitation threshold for diesel fuel atomization

Theory of dynamical cavitation threshold for vapor and non-condensable gas bubble nuclei is proposed based on a model equation constructed from Rayleigh–Plesset equation for glycerol, the liquid with viscosity higher than that of water by times, under a finite duration of strong tension. The model equation is ascertained to be valid in cases of strong tension under which cavitation occurs. Our model enables the study of dynamics of nuclei on the phase plane of the nucleus radius and the growth velocity, by which the full details of the threshold are revealed. We propose a dimensionless parameter to be used to classify the threshold of cavitation. Our model offers a simple mathematical expression to calculate the maximum radii attained, while under tension, for each of these three recognized patterns. For each observed pattern, we present unique predictive correlations for the radius of the nucleus growing for the tension duration. Moreover, we elucidate that the dynamics of the nuclei, grown up to certain sizes, is fully controlled by tension independent of the viscosity. The discrepancy between the dynamical threshold and the conventional Blake’s threshold is discussed. Finally, the utility of the theory presented here is demonstrated through numerical examples.