Fraction Of Electrons Research Articles

Теоретический анализ качества излучения и относительной биологической эффективности трития

Introduction 1. Tritium and reference radiation 1.1 Tritium isotope and its energy spectrum 1.2 Reference radiation 2. Methods for determining the quality of radiation and RBE 2.1 Radiation quality in microdosimetry 2.2 RBE by the number of DNA double-strand breaks 2.3 RBE by fraction of secondary low-energy electrons 3. Analysis of calculations of radiation quality and tritium RBE 3.1 Estimation of tritium emission quality factors 3.2 Evaluation of the RBE of tritium radiation during its action on DNA 3.3 Estimation of the RBE of tritium from the fraction of secondary low-energy electrons 3.4 Quality factors and RBE of tritium with respect to reference emissions Conclusion

Theoretical Study and Virtual Screening of Nitrogen‐Containing Corrosion Inhibitors Based on Quantitative Structure–Activity Relationship

AbstractNitrogen‐containing corrosion inhibitors have a wide range of promising applications, and current conventional corrosion design and evaluation methods are largely based on empirical speculation and extensive exploratory experiments. Unfortunately, these efforts are often associated with high costs, long lead times, and a lot of “blind work.” In this work, we have computationally screened the quantum chemical parameters of five nitrogen‐containing corrosion inhibitor molecules and their corrosion inhibition properties by a molecular simulation method based on density functional theory calculations. The ultimate relationship between the corrosion inhibition efficiency (IE) of an adsorbent and its quantum chemical parameters was analyzed using linear regression by comparing the various quantum mechanical parameters of each inhibitor molecule, as well as the fraction of electrons (ΔN) that are transferred to the metal surface from the chemisorbed inhibitor molecule. Five different nitrogen‐containing corrosion inhibitor molecules were screened based on structural similarity. Meanwhile, their corrosion inhibition performance was evaluated using the most relevant structure–activity equations. The results showed that the synergistic effect between the corrosion inhibition performance and the orbital energies of highest occupied molecular orbital and lowest unoccupied molecular orbital was optimal under the HF/6‐31G(d) method, and the corresponding structure–activity relationship was established. Based on these results, a specific inhibitor molecule was found to have excellent corrosion inhibition performance with a predicted corrosion IE of up to 94.12 %.

Secular Outflows from Long-Lived Neutron Star Merger Remnants

We study mass ejection from a binary neutron star merger producing a long-lived massive neutron star remnant with general-relativistic neutrino-radiation hydrodynamics simulations. In addition to outflows generated by shocks and tidal torques during and shortly after the merger, we observe the appearance of a wind driven by spiral density waves in the disk. This spiral-wave-driven outflow is predominantly located close to the disk orbital plane and have a broad distribution of electron fractions. At higher latitudes, a high electron-fraction wind is driven by neutrino radiation. The combined nucleosynthesis yields from all the ejecta components is in good agreement with Solar abundance measurements.

PET/SPECT/Spectral-CT/CBCT imaging in a small-animal radiation therapy platform: A Monte Carlo study-Part II: Biologically guided radiotherapy.

This study addresses the technical gap between clinical radiation therapy (RT) and preclinical small-animal RT, hindering the comprehensive validation of innovative clinical RT approaches in small-animal models of cancer and the translation of preclinical RT studies into clinical practices. The main aim was to explore the feasibility of biologically guided RT implemented within a small-animal radiation therapy (SART) platform, with integrated quad-modal on-board positron emission tomography (PET), single-photon emission computed tomography, photon-counting spectral CT, and cone-beam CT (CBCT) imaging, in a Monte Carlo model as a proof-of-concept. We developed a SART workflow employing quad-modal imaging guidance, integrating multimodal image-guided RT and emission-guided RT (EGRT). The EGRT algorithm was outlined using positron signals from a PET radiotracer, enabling near real-time adjustments to radiation treatment beams for precise targeting in the presence of a 2-mm setup error. Molecular image-guided RT, incorporating a dose escalation/de-escalation scheme, was demonstrated using a simulated phantom with a dose painting plan. The plan involved delivering a low dose to the CBCT-delineated planning target volume (PTV) and a high dose boosted to the highly active biological target volume (hBTV) identified by the 18F-PET image. Additionally, the Bayesian eigentissue decomposition method illustrated the quantitative decomposition of radiotherapy-related parameters, specifically iodine uptake fraction and virtual noncontrast (VNC) electron density, using a simulated phantom with Kidney1 and Liver2 inserts mixed with an iodine contrast agent at electron fractions of 0.01-0.02. EGRT simulations generated over 4,000 beamlet responses in dose slice deliveries and illustrated superior dose coverage and distribution with significantly lower doses delivered to normal tissues, even with a 2-mm setup error introduced, demonstrating the robustness of the novel EGRT scheme compared to conventional image-guided RT. In the dose-painting plan, doubling the dose to the hBTV while maintaining a low dose for the PTV resulted in an organ-at-risk (OAR) dose comparable to the low-dose treatment for the PTV alone. Furthermore, the decomposition of radiotherapy-related parameters in Kidney1 and Liver2 inserts, including iodine uptake fractions and VNC electron densities, exhibited average relative errors of less than 1.0% and 2.5%, respectively. The results demonstrated the successful implementation of biologically guided RT within the proposed quad-model image-guided SART platform, with potential applications in preclinical RT and adaptive RT studies.

A semi-analytical procedure to determine the ion recombination correction factor in high dose-per-pulse beams.

The conventional theories and methods of determining the ion recombination correction factor, such as Boag theory and the related two voltage method and Jaffé plot extrapolation, do not seem to yield accurate results in FLASH /high dose per pulse (DPP) beams ( 10 mGy DPP). This is due to the presence of a large free electron fraction that distorts the electric field inside the chamber sensitive volume. To understand the influence of these effects on the ion recombination correction factor and to develop new expressions for it, it is necessary to re-visit the underlyingphysics. To present a mathematical procedure to develop an analytical expression for the ion recombination correction factor. The expression is the basis for an extrapolation method so the correction factor can be determined in a clinical setting. A semi-analytical solution method, the homotopy perturbation method (HPM), is used to solve the partial differential equations(PDEs) describing the charge carrier physics, including space charge and free electrons. The electron velocity and attachment rate are modeled as functions of the electric field strength. An expression for the charge collection efficiency and ion recombination correction factor are developed. A fit procedure based on this expression is used to compare it to measured data from previously published articles. Another fit procedure using a general equationis also proposed and compared to the data. The series obtained for the charge collection efficiency and the ion recombination correction factor are determined to be asymptotic series and the optimal truncation established. The ion recombination correction factor exhibits a dependency due to the free electron presence. The fit using this expression agrees well with measured data as long as (1) the DPP is below 1 Gy for chambers with a 1 mm plate separation and (2) when the DPP is below 3 Gy for chambers with a 0.5 mm plate separation. In these DPP ranges, the deviation between measured and fit value did not exceed 6%. In both chamber cases the voltage range where the fit applies decreases as DPP increases. The general equationyielded comparable results. The HPM was shown to be applicable to a complex system of PDEs and generate meaningful and novel solutions, as they include both space charge and free electrons. The HPM also lends itself to other chamber geometries. The fit procedure was also shown to yield accurate results for the ion recombination correction up to the 1 Gy DPPlevel.

Theoretical Study of Khellin Derivatives as Corrosion Inhibitors Based on Density Functional Theory (DFT)

Theoretical studies of Khellin in the presence of electron donor and electron with-drawing groups as a corrosion inhibitor are investigated using the B3LYP/6-31G (d, p) theory level with Gaussian software. This research focuses on the correlation between corrosion inhibition efficiency (EI%) and quantum chemical parameters such as EHOMO (Highest Occupied Molecular Orbital Energy), ELUMO (Lowest Unoccupied Molecular Orbital Energy), energy gap (∆E), dipole moment (µ), absolute hardness (η), absolute softness (σ), the absolute electronegativity (χ), the fractions of electrons transferred from the inhibitor molecule to the metallic atom (∆N), the electrophilicity index (ω), total energy (ET) and theoretical corrosion inhibition efficiency (EI %). The generated results show that the electron-donating groups increase the corrosion inhibition efficiency of Khellin in the sequence -NH2> -SH> -H> -NCH2> -NO2. The highest corrosion inhibition efficiency obtained about 98.40% proves that NH2-Khellin is the best corrosion inhibitor of iron.

Cationic order-related magnetoresistivity and half-metallicity in bulk Pb2FeMoO6 grown by high pressure synthesis

We investigate the electric properties of Pb2FeMoO6 (PFMO), a double perovskite that can be grown in a bulk pure phase only via High Pressure/High Temperature solid-state reaction. The as-obtained PFMO is characterized by a high degree of cationic ordering at the B site between Fe3+ and Mo5+ and a ferrimagnetic transition with TN around 275 K. A semi-metallic to half-metallic transition seems to occur when the ferrimagnetic order arises thanks to the localization of a minority fraction of electrons on the Mo site. In this thermal regime, the system displays asymmetric magneto-resistivity, with selective-polarized carriers promoted by intense negative magnetic fields applied across the Néel transition during the cooling ramp. This cation-ordering related feature vanishes when the Mo-O bond length stabilizes, indicating a strong connection between the magnetic and electrical properties of this compound.

Mergers of double NSs with one high-spin component: brighter kilonovae and fallback accretion, weaker gravitational waves

ABSTRACT Neutron star (NS) mergers where both stars have negligible spins are commonly considered as the most likely ‘standard’ case. In globular clusters, however, the majority of NSs have been spun up to millisecond (ms) periods and, based on observed systems, we estimate that a non-negligible fraction of all double NS mergers ($\sim 4\pm 2\, {{\ \rm per\ cent}}$) contains one component with a spin of a (few) ms. We use the Lagrangian numerical relativity code SPHINCS_BSSN to simulate mergers where one star has no spin and the other has a dimensionless spin parameter of χ = 0.5. Such mergers exhibit several distinct signatures compared to irrotational cases. They form only one, very pronounced spiral arm and they dynamically eject an order of magnitude more mass of unshocked material at the original, very low electron fraction. One can therefore expect particularly bright, red kilonovae. Overall, the spinning case collisions are substantially less violent and they eject smaller amounts of shock-generated semirelativistic material. Therefore, the ejecta produce a weaker blue/ultraviolet kilonova precursor signal, but – since the total amount is larger – brighter kilonova afterglows months after the merger. The spinning cases also have significantly more fallback accretion and thus could power late-time X-ray flares. Since the post-merger remnant loses energy and angular momentum significantly less efficiently to gravitational waves, such systems can delay a potential collapse to a black hole and are therefore candidates for merger-triggered gamma-ray bursts with longer emission time-scales.

Dynamics of baryon ejection in magnetar giant flares: implications for radio afterglows, r-process nucleosynthesis, and fast radio bursts

ABSTRACT We explore the impact of a magnetar giant flare (GF) on the neutron star (NS) crust, and the associated baryon mass ejection. We consider that sudden magnetic energy dissipation creates a thin high-pressure shell above a portion of the NS surface, which drives a relativistic shockwave into the crust, heating a fraction of these layers sufficiently to become unbound along directions unconfined by the magnetic field. We explore this process using spherically symmetric relativistic hydrodynamical simulations. For an initial shell pressure PGF we find the total unbound ejecta mass roughly obeys the relation $M_{\rm {ej}}\sim 4\!-\!9\times 10^{24}\, \rm {g}\, (P_{\rm GF}/10^{30}\, \rm {erg}\, \rm {cm}^{-3})^{1.43}$. For $P_{\rm {GF}}\sim 10^{30}\!-\!10^{31}\, \rm {erg}\, \rm {cm}^{-3}$ corresponding to the dissipation of a magnetic field of strength $\sim 10^{15.5}\!-\!10^{16}\, \rm {G}$, we find $M_{\rm {ej}}\sim 10^{25}\!-\!10^{26}\, \rm {g}$ with asymptotic velocities vej/c ∼ 0.3–0.6 compatible with the ejecta properties inferred from the afterglow of the 2004 December GF from SGR 1806-20. Because the flare excavates crustal material to a depth characterized by an electron fraction Ye ≈ 0.40–0.46, and is ejected with high entropy and rapid expansion time-scale, the conditions are met for heavy element r-process nucleosynthesis via the alpha-rich freeze-out mechanism. Given an energetic GF rate of roughly once per century in the Milky Way, we find that magnetar GFs could be an appreciable heavy r-process source that tracks star formation. We predict that GFs are accompanied by short ∼minutes long, luminous $\sim 10^{39}\, \rm {erg}\, \rm {s}^{-1}$ optical transients powered by r-process decay (nova brevis), akin to scaled-down kilonovae. Our findings also have implications for the synchrotron nebulae surrounding some repeating fast radio burst sources.

Spectroscopic r-process Abundance Retrieval for Kilonovae. II. Lanthanides in the Inferred Abundance Patterns of Multicomponent Ejecta from the GW170817 Kilonova

In kilonovae, freshly synthesized r-process elements imprint features on optical spectra, as observed in AT2017gfo, the counterpart to the GW170817 binary neutron star merger. However, measuring the r-process compositions of the merger ejecta is computationally challenging. Vieira et al. introduced Spectroscopic r-process Abundance Retrieval for Kilonovae (SPARK), a software tool to infer elemental abundance patterns of the ejecta and associate spectral features with particular species. Previously, we applied SPARK to the 1.4-day spectrum of AT2017gfo and inferred its abundance pattern for the first time, characterized by electron fraction Y e = 0.31, a substantial abundance of strontium, and a dearth of lanthanides and heavier elements. This ejecta is consistent with wind from a remnant hypermassive neutron star and/or accretion disk. We now extend our inference to spectra at 2.4 and 3.4 days and test the need for multicomponent ejecta, where we stratify the ejecta in composition. The ejecta at 1.4 and 2.4 days is described by the same single blue component. At 3.4 days, a new redder component with lower Y e = 0.16 and a significant abundance of lanthanides emerges. This new redder component is consistent with dynamical ejecta and/or neutron-rich ejecta from a magnetized accretion disk. As expected from photometric modeling, this component emerges as the ejecta expands, the photosphere recedes, and the earlier bluer component dims. At 3.4 days, we find an ensemble of lanthanides, with the presence of cerium most concrete. This presence of lanthanides has important implications for the contribution of kilonovae to the r-process abundances observed in the Universe.

Nucleosynthetic Analysis of Three-dimensional Core-collapse Supernova Simulations

We study in detail the ejecta conditions and theoretical nucleosynthetic results for 18 three-dimensional core-collapse supernova (CCSN) simulations done by Fornax. Most of the simulations are carried out to at least 3 s after bounce, which allows us to follow their longer-term behaviors. We find that multidimensional effects introduce many complexities into the ejecta conditions. We see a stochastic electron fraction evolution, complex peak temperature distributions and histories, and long-tail distributions of the time spent within nucleosynthetic temperature ranges. These all lead to substantial variation in CCSN nucleosynthetic yields and differences from 1D results. We discuss the production of lighter α-nuclei, radioactive isotopes, heavier elements, and a few isotopes of special interest. Comparing pre-CCSN and CCSN contributions, we find that a significant fraction of elements between roughly Si and Ge are generally produced in CCSNe. We find that 44Ti exhibits an extended production timescale as compared to 56Ni, which may explain its different distribution and higher than previously predicted abundances in supernova remnants such as Cas A and SN1987A. We also discuss the morphology of the ejected elements. This study highlights the high-level diversity of ejecta conditions and nucleosynthetic results in 3D CCSN simulations and emphasizes the need for additional long-term (∼10 s) 3D simulations to properly address such complexities.

Inhibition performances of new pyrazole derivatives against the corrosion of C38 steel in acidic medium: Computational study

Corrosion inhibition performances of two new pyrazole derivatives, namely 5-(4-dimethylamino)phenyl)-3-(4-dimethylamino)styryl)-4,5-dihydro-1H-pyrazole-1-carbothio amide (P1) and 5-(4-dimethylamino)phenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-carbothio amide (P2) against the corrosion of carbon steel in acidic medium are theoretically investigated by combination of the density functional theory with the molecular dynamics approach. Additionally, the toxicity and solubility of the aforementioned molecules were investigated. Quantum chemical parameters of considered molecules (calculated energy levels of HOMO and LUMO molecular orbitals as well as the gap between them, hardness, softness, chemical potential, electronegativity, electrophilicity index, nucleophilicity, electro donating power, electro accepting power, polarizability, dipole moment, metal-inhibitor interaction energy, the fraction of electrons transferred from inhibitors to metal surface, back-donation energy, Fukui indices) were calculated at B3LYP/SVP, CAM-B3lyp/TZVP and ωB97XD/Def2-TZVP levels of theory. Comparative calculations were performed in the gaseous phase and in the aqueous solutions. The adsorption behavior of the mentioned molecules on the Fe (110) surface was investigated with the molecular dynamics. Both considered molecules demonstrates high adsorption energies on steel surface, low toxicity and high solubility. P1 is found to be more efficient in hydrochloric acid, whereas P2 molecule is found to be more efficient in sulfuric acid.

On the treatment of phenomenological turbulent effects in one-dimensional simulations of core-collapse supernovae

ABSTRACT We have developed a phenomenological turbulent model with one-dimensional (1D) simulation based on Reynolds decomposition. Using this method, we have systematically studied models with different effects of compression, mixing length parameters, and diffusion coefficient of internal energy, turbulence energy, and electron fraction. With employed turbulent effects, supernova explosion can be achieved in 1D geometry, which can mimic the evolution of shock in the 3D simulations. We found that enhancement of turbulent energy by compression affects the early shock evolution. The diffusion coefficients of internal energy and turbulent energy also affect the explodability. The smaller diffusion makes the shock revival faster. Our comparison between the two reveals that the diffusion coefficients of internal energy has a greater impact. These simulations would help understand the role of turbulence in core-collapse supernovae.

Ab initio investigation of hot electron transfer in CO2 plasmonic photocatalysis in the presence of hydroxyl adsorbate.

Photoreduction of carbon dioxide (CO2) on plasmonic structures is of great interest in photocatalysis to aid selectivity. While species commonly found in reaction environments and associated intermediates can steer the reaction down different pathways by altering the potential energy landscape of the system, they are often not addressed when designing efficient plasmonic catalysts. Here, we perform an atomistic study of the effect of the hydroxyl group (OH) on CO2 activation and hot electron generation and transfer using first-principles calculations. We show that the presence of OH is essential in breaking the linear symmetry of CO2, which leads to a charge redistribution and a decrease in the OCO angle to 134°, thereby activating CO2. Analysis of the partial density of states (pDOS) demonstrates that the OH group mediates the orbital hybridization between Au and CO2 resulting in more accessible states, thus facilitating charge transfer. By employing time-dependent density functional theory (TDDFT), we quantify the fraction of hot electrons directly generated into hybridized molecular states at resonance, demonstrating a broader energy distribution and an 11% increase in charge-transfer in the presence of OH groups. We further show that the spectral overlap between excitation energy and plasmon resonance plays a critical role in efficiently modulating electron transfer processes. These findings contribute to the mechanistic understanding of plasmon-mediated reactions and demonstrate the importance of co-adsorbed species in tailoring the electron transfer processes, opening new avenues for enhancing selectivity.

Computational Investigation of Corrosion Inhibition Properties of Hydrazine and Its Derived Molecules for Mild Steel

Corrosion of mild steel has gained a lot of attention by many industries and academia. This study was aimed to find the corrosion inhibition properties of hydrazine and its 11 derived molecules for mild steel using computational method, namely, the density functional theory with Beck 3‐parameter Lee Yang and Parr functional along with the 6‐311++G (d, p) basis set using simple quantum chemical parameters. The main quantum chemical parameters were energies of highest occupied and lowest unoccupied molecular orbitals and their energy gap, dipole moment, hardness, softness, electrophilicity index, the fractions of electrons transmitted, the change energy back‐donation, electron‐donating power, electron‐accepting power, molecular electrostatic potential, and Fukui function as well as polarizability. The results indicated that hydrazine derivatives have good anticorrosion nature which is consistent with the experimental findings. Out of the 12 target inhibitor molecules, N′‐(3‐nitrobenzylidene) hydrazine carbodithioic acid (NBHCA) and N′‐(4‐dimethylaminobenzylidene) hydrazine carbodithioic acid (DABHCA) are the most effective inhibitors. According to the value of the quantum chemical parameters, EHOMO, ΔEgap, Χ, η, σ, ε, ΔN, α, and ΔEb-d DABHCA showed the top effective anticorrosion inhibitor, and by the value of the quantum chemical parameters, ELUMO, TE, ω−, and ω+ NBHCA showed an effective anticorrosion inhibitor. The quantum chemical parameter data showed that NBHCA and DABHCA are nearly equivalent in their values, which is consistent with experimental values. Furthermore, a multiple‐linear regression equation was proposed as a quantitative structural activity relationship model to relate the calculated molecular descriptors of hydrazine derivatives to their experimental inhibition efficiencies obtained from literature. As a result, this model showed an excellent accuracy with an R‐squared of 0.924 and this uses to predict inhibition efficiencies of another molecules.

Corrosion Inhibition of Mild Steel in HCl Solution Using MPO: Experimental and Theoretical Insights

Corrosion is a pervasive challenge in various industrial applications, particularly in acidic environments. This comprehensive study delves into the effectiveness of 2-methyl-4-propyl-1,3-oxathiane (MPO) as a corrosion inhibitor for mild steel exposed to hydrochloric acid (HCl) solutions. The investigation employs weight loss techniques to assess the inhibitor's performance over varying durations (ranging from 1 to 48 hours) and concentrations (0.1 to 1 mM). At a concentration of 0.5 mM, the inhibitor demonstrates impressive inhibitory efficiency, ranging from 87.6% at 303 K to 92.9% at 333 K during a 5-hour exposure period. Additionally, the impact of temperature on the corrosion inhibition process is examined at temperatures of 303, 313, 323, and 333 K, showing substantial inhibition efficiencies. Quantum chemical calculations using Density Functional Theory (DFT) methods elucidate the molecular interactions between MPO and the metal surface. Notably, the analysis of EHOMO (Highest Occupied Molecular Orbital Energy), ELUMO (Lowest Unoccupied Molecular Orbital Energy), Egap (Energy Gap), total hardness (η), electronegativity (χ), and electron fraction transition atom (ΔN) reveals valuable insights into MPO's corrosion inhibition capabilities. The outcomes underscore MPO's potential as an effective corrosion inhibitor for mild steel in HCl environments, laying the groundwork for more efficient corrosion prevention strategies in industrial settings.

SON KULLANMA TARİHİ GEÇMİŞ BİR İLACIN İNHİBİSYON ETKİNLİĞİ ÜZERİNE PROTONASYONUNUN DEĞERLENDİRİLMESİNE YÖNELİK TEORİK BİR YAKLAŞIM

The quantum theoretical calculations were performed to elucidate the corrosion inhibition efficiency of an expired drug. For this purpose, molecular orbital analysis, which is used in the analysis of chemical interactions and gives detailed data about the electronic structure of molecules, was used to gain insight into the electronic properties of the selected drug molecule in neutral and aqueous form. The calculations were carried out at the (B3LYP) 6-311G**(d,p) basis set level utilizing density functional theory (DFT) to examine the relationship between the molecular structure and inhibition efficiency of the corresponding drug molecule. Various quantum chemical descriptors such as highest occupied molecular orbital energy (HOMO), lowest unoccupied molecular orbital energy (LUMO), energy gap (ΔE), dipole moment (μ), ionization potential (I), electron affinity (A), electronegativity (χ), hardness (η), softness (σ), back donation (ΔEback- donation) and fraction of electrons transferred (ΔN) were calculated and correlated to the inhibition efficiency. The most probable nucleophilic and electrophilic reactive sites of studied drug molecule were analyzed through computed Fukui indices. Overall, obtained theoretical data indicate that the quantum chemical parameters correlate well with the inhibition performance.

Particle acceleration by sub-proton cyclotron frequency spectrum of dispersive Alfven waves in inhomogeneous solar coronal plasmas

ABSTRACT The problem of explaining observed soft X-ray fluxes during solar flares, which invokes acceleration of large fraction of electrons, if the acceleration takes places at the solar coronal loop-top, can potentially be solved by postulating that flare at loop-top creates dispersive Alfven waves (DAWs) which propagate towards the foot-points. As DAWs move in progressively denser parts of the loop (due to gravitational stratification) the large fraction of electrons is no longer needed. Here, we extend our previous results by considering f−1 frequency spectrum of DAWs and add He++ ions using fully kinetic particle-in-cell (PIC) simulations. We consider cases when transverse density gradient is in the range 4–40c/ωpe and DAW driving frequency is 0.3–0.6ωcp. We find that (i) The frequency spectrum case does not affect electron acceleration fraction in the like-to-like cases, but few times larger percentage of He++ heating is seen due to ion cyclotron resonance; (ii) In cases when counter propagating DAWs collide multiple-times, much larger electron and ion acceleration fractions are found, but the process is intermittent in time. This is because intensive heating (temperature increase) makes the-above-thermal-fraction smaller; Also more isotropic velocity distributions are seen; (iii) Development of kink oscillations occurs when DAWs collide; (iv) Scaling of the magnetic fluctuations power spectrum steepening in the higher-density regions is seen, due to wave refraction. Our PIC runs produce much steeper slopes than the orginal spectrum, indicating that the electron-scale physics has a notable effect on DAW spectrum evolution.

Perbandingan Algoritma Multilinear Regression dan Decision Tree Regressor dalam Memprediksi Efisiensi Penghambatan Korosi Piridazin

Corrosion is one of the main problems in various industries, causing increased production costs, maintenance expenses, and decreased equipment efficiency. Inhibitors, especially organic compounds, have become an increasingly sought-after solution to reduce corrosion in an effective and environmentally friendly manner. This research aims to compare linear algorithms based on multilinear regression (MLR) and nonlinear algorithms based on decision tree regressor (DTR) for a case study of predicting corrosion inhibition efficiency (CIE) values of pyridazine derivative compounds as corrosion inhibitors. This research is a data-based theoretical study using a machine learning (ML) approach. In this study, we used a dataset of pyridazine compounds from published literature consisting of 20 pyridazine compounds with molecular properties as features (independent variables) and CIE values as targets (dependent variables). The analysis consists of analyzing the prediction model's performance and important features that support model performance. The research results show that the DTR-based nonlinear model has better performance than the MLR-based linear model based on evaluation metrics and prediction data distribution plots. We also find that the molecular properties fraction of electron transferred (∆N) and electron affinity (A) respectively emerge as the features most responsible for the prediction performance of the DTR model. We conclude that the DTR-based nonlinear algorithm can be used as an accurate and reliable predictive model to predict the corrosion inhibition ability for potential new pyridazine derivative compounds.

Ab-initio General-relativistic Neutrino-radiation Hydrodynamics Simulations of Long-lived Neutron Star Merger Remnants to Neutrino Cooling Timescales

We perform the first 3D ab-initio general-relativistic neutrino-radiation hydrodynamics of a long-lived neutron star merger remnant spanning a fraction of its cooling timescale. We find that neutrino cooling becomes the dominant energy loss mechanism after the gravitational-wave dominated phase (∼20 ms postmerger). Electron flavor antineutrino luminosity dominates over electron flavor neutrino luminosity at early times, resulting in a secular increase of the electron fraction in the outer layers of the remnant. However, the two luminosities become comparable ∼20–40 ms postmerger. A dense gas of electron antineutrinos is formed in the outer core of the remnant at densities ∼1014.5 g cm−3, corresponding to temperature hot spots. The neutrinos account for ∼10% of the lepton number in this region. Despite the negative radial temperature gradient, the radial entropy gradient remains positive, and the remnant is stably stratified according to the Ledoux criterion for convection. A massive accretion disk is formed from the material squeezed out of the collisional interface between the stars. The disk carries a large fraction of the angular momentum of the system, allowing the remnant massive neutron star to settle to a quasi-steady equilibrium within the region of possible, stable, rigidly rotating configurations. The remnant is differentially rotating, but it is stable against the magnetorotational instability. Other MHD mechanisms operating on longer timescales are likely responsible for the removal of the differential rotation. Our results indicate the remnant massive neutron star is thus qualitatively different from a protoneutron stars formed in core-collapse supernovae.