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Transition metal (Ti, Zr, Pd, Pt) doping on boron nitride nanotubes for enhanced curcumin binding: A theoretical insight
No full textDetection and adsorption behavior of the curcumin molecule on pristine boron nitride nanotube (BNNT) and transition metal (TM = Ti, Zr, Pd, and Pt)-doped (5,5) armchair BNNT was investigated using a density functional theory (DFT) analysis. Structural, energetic, and electronic properties of pristine and TM-doped BNNT, as well as their complexes with curcumin, were systematically investigated to assess their potential as drug delivery or sensing materials. The computed results display that the adsorption processes for all curcumin/BNNT and curcumin/TM-doped BNNT complexes are exothermic reaction. Two adsorption sites on the curcumin molecule were analyzed: the M site (central carbonyl and hydroxyl groups) and the H site (terminal phenolic OH and methoxy groups). Whereas pristine BNNT shows weak interactions at both sites, TM-doped BNNTs exhibit strong binding, particularly at the M site, in both gas and aqueous phases. A short adsorption distance and substantial charge transfer indicate a strong adsorption ability of the TM-doped BNNTs toward the curcumin molecule. The electronic structures of both pristine BNNT and TM-doped BNNTs are altered upon curcumin adsorption, as evidenced by changes in the energy gap, quantum molecular descriptors, and density of states plots. Therefore, the TM-doped BNNTs serve as a promising material for the delivery and sensing of curcumin molecule
Characterisation and Validation of Submicron Structures in a Fe–Al–Nb Alloy Using Inverse Modelling of the
No full textUsing conventional matrix correction methods, the spatial resolution of EPMA is limited by the size of the electron interaction volume. Secondary and back-scattered electron imaging techniques achieve higher spatial resolution, but can only provide structural information at the surface of the sample. In this study, we present a method for reconstructing complex three-dimensional material structures in EPMA by means of inverse modelling, based on the deterministic spherical harmonic PN method for simulating electron transport in solids. We apply this approach to characterise submicron structures in an Fe-Al-Nb alloy, where the structural features are smaller than the interaction volume. The accuracy of the reconstructed material structure is further validated by comparing with cross-sectional micro-structural information obtained via FIB/SEM tomography
Using EBSD analysis for exploring the recrystallization behavior of hot-rolled Mg-Gd alloy
No full textThe microstructure, texture and mechanical properties of a Mg-0.6Gd (wt.%) alloy processed by hot-rolling at 450 °C to 85% of thickness reduction and subsequently annealed at temperatures ranging from 150 to 450 °C for 1 h were investigated using electron backscatter diffraction (EBSD) and Vickers microhardness measurements. The microhardness increased from 51.2 to 56.3 Hv with increasing annealing temperature at 250 °C due to the precipitation of the Mg5Gd phase and then decreased gradually to 38.5 Hv up to 450 °C owing to the static recrystallization and grain growth. Meanwhile, the recrystallized grain size was stable up to annealing at 250 °C (~ 1 μm) and then increased significantly to a value of 39 μm at 450 °C. Limited dynamic recrystallization, particle-stimulated nucleation and recrystallization at shear bands are the main mechanisms leading to the weakening and spreading of the deformation basal texture during the isochronal annealing treatment
Development of an adjoint flux calculation technique for exact perturbation theory in Monte Carlo transport
No full textA calculation technique computing the adjoint flux of perturbed system is developed for the exact perturbation theory in Monte Carlo transport. By using a correlated sampling and iterated fission probability methods together, the adjoint flux of perturbed system is calculated during a forward Mote Carlo simulation of an unperturbed system. In the perturbation-included iterated fission probability method, no additional particle simulation is required to compute the adjoint flux of perturbed system. The exact perturbation method is implemented in the Monte Carlo code MCS. The results of perturbation method for k-eigenvalue change are compared against differential operator sampling, adjoint-weighted perturbation, and direct perturbation methods for the Godiva benchmark and PLUS7 fuel assembly
Partial conservation of seniority in semi-magic nuclei
No full textThe concept of seniority plays a central role in nuclear structure physics by classifying many-body states according to the number of unpaired nucleons. While exact seniority conservation holds in single-j systems with , deviations arise for higher-j orbitals where residual interactions can mix states of different seniority. Surprisingly, certain states in systems with exhibit partial conservation of seniority, remaining solvable even when the symmetry is expected to break. This paper reviews the theoretical foundation of the seniority scheme, its connection to pairing interactions and coefficients of fractional parentage, and the conditions under which solvability persists. Particular emphasis is placed on the case, where two states with and remain unmixed under arbitrary interactions. We discuss analytical proofs of their existence, numerical studies, and supporting experimental evidence from semi-magic nuclei across five regions of the nuclear chart. Extensions to symbolic shell-model approaches are also presented, highlighting their utility in exploring wave functions and symmetries in many-body systems
Two-scale integrators with high accuracy and long-time conservations for the nonlinear Klein-Gordon equation in the nonrelativistic limit regime
No full textIn this paper, we are concerned with two-scale integrators for the non-relativistic Klein-Gordon (NRKG) equation with a dimensionless parameter 0 < ε ≪ 1, which is inversely proportional to the speed of light. The highly oscillatory property in time of this model corresponds to the parameter ε and the equation in the form of has a factor 1/ε2 in front of the nonlinearity which means that this part becomes strong when ε is small. We propose a class of two-scale integrators which is constructed based on some reformulations to the system, Fourier pseudo-spectral method and exponential integrators. Two practical integrators up to order three and four are constructed by using some symmetric conditions and the stiff order conditions of implicit exponential integrators. The convergence of the obtained integrators is rigorously studied, and it is shown that the uniform accuracy in time is (h3) and (h4) for the time stepsize h. The near energy conservation over long times is also established for the multi-stage integrators by using modulated Fourier expansions. Numerical results on a NRKG equation show that the proposed integrators have high accuracy, excellent long time energy conservation and competitive efficiency
ICRF Antenna Modeling and Coupling Analysis for CFEDR
No full textThe Ion Cyclotron Range of Frequencies (ICRF) is an important auxiliary plasma heating method in the Chinese Fusion Engineering DEMO Reactor (CFEDR). A coupled ICRF power Pc of 10 MW during the ramp-up phase and 20 MW during the flat-top phase is required, launched from an ICRF antenna located at an equatorial port, to obtain or sustain conventional H-mode in CFEDR. Using the CFETR-ICRF antenna model by Zhang et al [10], we use RAPLICASOL code to evaluate ICRF wave coupling across various plasma conditions and toroidal phasings. The analysis of the antenna coupling resistance Rc, power spectrum, parallel wavenumber k∥, surface current distribution on the straps Js, and parallel electric field E∥ under different edge electron density ne profiles and toroidal phasings [(0, π, 0, π, 0, π), (0, π, π, 0, 0, π), and (0, 0, π, π, 0, 0)], for frequencies between 40 MHz and 90 MHz, are presented
Comparison of Travelling Wave Array and Classical ICRH Launchers: Spectral and Absorption Characteristics on WEST
No full textIon Cyclotron Resonance Heating (ICRH) plays a central role in plasma heating and current drive in tokamaks, making the optimization of antenna systems essential for maximizing performance. In this context, a comparative analysis of classical and Travelling Wave Array (TWA) launchers is carried out to assess potential improvements in absorption efficiency and spatial localization of deposited power. Simulations using the EVE code focus on Hydrogen minority heating in a Deuterium plasma under a magnetic field of 3.657 T in WEST. The results show that Hydrogen absorbs the most power for parallel wavenumbers
k∥max between 8 and 10 rad/m. Peak absorption occurs near the plasma core at 55.5 MHz with a poloidal phasing angle of 45◦ between rows. Moreover, changing the sign of the TWA’s toroidal spectrum i.e., launching waves in the opposite toroidal direction has a small impact on power absorption by Hydrogen
Ion Cyclotron Heating in a Levitated Dipole Fusion Reactor
No full textOpenStar Technologies is pursuing the levitated dipole (LD) as a highly modular, loosely-coupled system that leverages their expertise in high temperature superconductor (HTS) technology. The next generation experiment at OpenStar, Tahi (Ma¯ori for “first”), will demonstrate the generation and confinement of fast ions in a levitated dipole for the first time. Ion cyclotron range of frequency (ICRF) heating is a leading candidate for energetic ion formation in Tahi. A frequency in the 10 MHz range will be used for H minority heating or D majority heating with waves launched from an antenna located above the floating coil. Unlike a tokamak, where the targeted cyclotron resonance is typically a vertical path through the center of the plasma, in a dipole the resonance location follows a C-shaped path from the separatrix to the center of the plasma. The value of
B also varies significantly within the confined plasma resulting in a large number of cyclotron harmonics present in the low field region. Furthermore, levitated dipoles contain a “first closed flux surface” surrounding the floating coil, in addition to the traditional separatrix
/last closed flux surface. Simulation e
fforts using full-wave ICRF codes show that ICRF heating of a levitated dipole reactor is feasible using a pair of toroidal current straps phased to launch the appropriate parallel (
i.e. poloidal) refractive index
Where does the simplified stellar contamination model fail in exoplanet transmission spectroscopy?
No full textStellar photospheric heterogeneities (e.g., starspots and faculae) distort the apparent stellar spectrum during a transit and imprint wavelength-dependent biases on the measured planet–to–star radius ratio. This transit light source effect (TLSE) must be accounted for to obtain reliable atmospheric properties. A widely used approach is the Rackham–TLSE (R–TLSE) prescription, which applies a disk-averaged contamination correction based solely on the filling factor and spectral contrast. However, accurate transmission-spectroscopy interpretations require models that also account for limb darkening, the spatial distribution of active regions, and transit geometry. In this work, we incorporated these effects into a self-consistent, pixel-resolved framework, ECLIPSE-