In Silico Study to Enhance Delivery Efficiency of Charged Nanoscale Nasal Spray Aerosols to the Olfactory Region Using External Magnetic Fields

Various factors and challenges are involved in efficiently delivering drugs using nasal sprays to the olfactory region to treat central nervous system diseases. In this study, computational fluid dynamics was used to simulate nasal drug delivery to (1) examine effects on drug deposition when various external magnetic fields are applied to charged particles, (2) comprehensively study effects of multiple parameters (i.e., particle aerodynamic diameter; injection velocity magnitude, angle, and position; magnetic force strength and direction), and (3) determine how to achieve the optimal delivery efficiency to the olfactory epithelium. The Reynolds-averaged Navier–Stokes equations governed airflow, with a realistic inhalation waveform implemented at the nostrils. Particle trajectories were modeled using the one-way coupled Euler–Lagrange model. A current-carrying wire generated a magnetic field to apply force on charged particles and direct them to the olfactory region. Once drug particles reached the olfactory region, their diffusion through mucus to the epithelium was calculated analytically. Particle aerodynamic diameter, injection position, and magnetic field strength were found to be interconnected in their effects on delivery efficiency. Specific combinations of these parameters achieved over 65-fold higher drug delivery efficiency compared with uniform injections with no magnetic fields. The insight gained suggests how to integrate these factors to achieve the optimal efficiency.

Weyl Fermion magneto-electrodynamics and ultralow field quantum limit in TaAs

Infrared spectroscopy in high magnetic fields reveals the lowest quantum limit in a Weyl semimetal.

Dynamic compression of water to conditions in ice giant interiors

Recent discoveries of water-rich Neptune-like exoplanets require a more detailed understanding of the phase diagram of H2O at pressure–temperature conditions relevant to their planetary interiors. The unusual non-dipolar magnetic fields of ice giant planets, produced by convecting liquid ionic water, are influenced by exotic high-pressure states of H2O—yet the structure of ice in this state is challenging to determine experimentally. Here we present X-ray diffraction evidence of a body-centered cubic (BCC) structured H2O ice at 200 GPa and ~ 5000 K, deemed ice XIX, using the X-ray Free Electron Laser of the Linac Coherent Light Source to probe the structure of the oxygen sub-lattice during dynamic compression. Although several cubic or orthorhombic structures have been predicted to be the stable structure at these conditions, we show this BCC ice phase is stable to multi-Mbar pressures and temperatures near the melt boundary. This suggests variable and increased electrical conductivity to greater depths in ice giant planets that may promote the generation of multipolar magnetic fields.

Monte Carlo investigation of electron fluence perturbation in MRI-guided radiotherapy beams using six commercial radiation detectors

With the integration of MRI-linacs to the clinical workflow, the understanding and characterization of detector response in reference dosimetry in magnetic fields are required. The magnetic field perturbs the electron fluence (Fe), and the degree of perturbation depends on the irradiation conditions and the detector type. This work evaluates the magnetic field impact on the electron fluence spectra in several detectors to provide a deeper understanding of detector response in these conditions. Monte Carlo calculations of Fe are performed in six detectors (solid-state: PTW60012 and PTW60019, ionization chambers: PTW30013, PTW31010, PTW31021, and PTW31022) placed in water and irradiated by an Elekta Unity 7 MV FFF photon beam with small and reference fields, at 0 T and 1.5 T. Three chamber-axis orientations are investigated: parallel or perpendicular (two possibilities: FL towards the stem or the tip) to the magnetic field and perpendicular to the beam. One orientation for the solid-state detector is studied: parallel to the beam and perpendicular to the magnetic field. Additionally, Fe spectra are calculated in modified detector geometries to identify the underlying physical mechanisms behind the fluence perturbations. The total Fe is reduced up to 1.24% in the farmer chamber, at 1.5 T, in the parallel orientation. The interplay between the gyration radius and the farmer chamber cavity length significantly affects Fe in the perpendicular orientation; the total fluence varies up to 5.12% in magnetic fields. For the small-cavity chambers, the maximal variation in total Fe is 0.19%, for the reference field, in the parallel orientation. . In contrast, significant small-field effects occur; the total Fe is reduced between 9.86% to 14.50% at 1.5T (with respect to 0T) depending on the orientation. The magnetic field strongly impacted the solid-state detectors in both field sizes, probably due to the high-density extracameral components. The maximal reductions of total Fe are 15.06±0.09% (silicon) and 16.00±0.07% (microDiamond). This work provides insights into detector response in magnetic fields by illustrating the interplay between several factors causing dosimetric perturbation effects: 1) chamber and magnetic field orientation, 2) cavity size and shape, 3) extracameral components, 4) air gaps and their asymmetry, 5) electron energy. Low-energy electron trajectories are more susceptible to change in magnetic fields, and generally, they are associated with detector response perturbation.

Screening of magnetic fields by superconducting and hybrid shields with circular cross-section

The use of superconducting (SC) materials is crucial for shielding quasi-static magnetic fields. However, the frequent requisite of space-saving solutions with high shielding performance requires the development of a 3D modelling procedure capable of predicting the screening properties for different orientations of the applied field. In this paper, we exploited a 3D numerical model based on a vector potential formulation to investigate the shielding ability of SC screens with cylindrical symmetry and a height/diameter aspect ratio close to unity, without and with the superimposition of a ferromagnetic (FM) circular shell. The chosen materials were MgB2 and soft iron. First, the calculation outcomes were compared with the experimental data obtained on different shielding arrangements, achieving a notable agreement in both axial-field (AF) and transverse-field (TF) orientations. Then, we used the thus validated modelling approach to investigate how the magnetic mitigation properties of a cup-shaped SC bulk can be improved by the superimposition of a coaxial FM cup. Calculations highlighted that the FM addition is very efficient in enhancing the shielding factors (SFs) in the TF orientation. Assuming a working temperature of 30 K and using a layout with the FM cup protruding over the SC one, shielding factors up to 8 times greater than those of the single SC cup were attained at low applied fields, reaching values equal or higher than 102 in the inner half of the shield. In the AF orientation, the same FM cup addition costs a modest worsening at low fields, but at the same time, it widens the applied field range, where SF ≥ 104 occurs near the close extremity of the shield, up over 1 T.

Magnetization of carbonaceous asteroids by nebular fields and the origin of CM chondrites

The solar nebula carried a strong magnetic field that had a stable intensity and direction for periods of a thousand years or more1. The solar nebular field may have produced post-accretional magnetization in at least two groups of meteorites, CM and CV chondrites [1–3], which originated from planetesimals that may have underwent aqueous alteration before gas in the solar nebula dissipated [1,3]. Magnetic minerals produced during aqueous alteration, such as magnetite and pyrrhotite [4], could acquire a chemical remanent magnetization from that nebular field [3]. However, many questions about the size, composition, formation time, and, ultimately, identity of the parent bodies that produced magnetized CM and CV chondrites await answers—including whether a parent body might exhibit a detectable magnetic field today. Here, we use thermal evolution models to show that planetesimals that formed between a few Myr after CAIs and ~1 Myr before the nebular gas dissipated could acquire from the nebular field, and retain until today, a chemical remanent magnetization throughout nearly their entire volume. Hence, in-situ magnetometer measurements of C-type asteroids could help link magnetized asteroids to magnetized meteorites. Specifically, a future mission could search for a magnetic field as part of testing the hypothesis that 2 Pallas is the parent body of the CM chondrites [5]. Overall, large carbonaceous asteroids might record ancient magnetic fields in magnetic remanence that produces strong modern magnetic fields, even without a metallic core that once hosted a dynamo.