Optical one-dimensional waveguides in oxyfluoride glass fabricated by Helium Ion implantation

In this work, a one-dimensional waveguide is formed by virtue of the helium ion implantation in the oxyfluoride glass (OFG). The energy and the fluence of the ion implantation are 0.4 MeV and [Formula: see text] [Formula: see text], respectively. The m-line curve with the effective refractive indices of the modes was recorded by using the prism coupling system. The energy loss distribution and the refractive index profile were calculated by the stopping and range of ions into matter (SRIM)-2013 and the RCM, respectively. The light modal profile was measured by the end-facet coupling system. It suggests that the He[Formula: see text]-ion implanted OFG waveguides have the potential to act as integrated photonic devices.

The Evolution of Lateral Dose Distributions of Helium Ion Beams in Air: From Measurement and Modeling to Their Impact on Treatment Planning

To start clinical trials with the first clinical treatment planning system supporting raster-scanned helium ion therapy, a comprehensive database of beam characteristics and parameters was required for treatment room-specific beam physics modeling at the Heidelberg Ion-Beam Therapy Center (HIT). At six different positions in the air gap along the beam axis, lateral beam profiles were systematically measured for 14 initial beam energies covering the full range of available energies at HIT. The 2D-array of liquid-filled ionization chambers OCTAVIUS from PTW was irradiated by a pencil beam focused at the central axis. With a full geometric representation of HIT’s monitoring chambers and beamline elements in FLUKA, our Monte Carlo beam model matches the measured lateral beam profiles. A second set of measurements with the detector placed in a water tank was used to validate the adjustments of the initial beam parameters assumed in the FLUKA simulation. With a deviation between simulated and measured profiles below ±0.8 mm for all investigated beam energies, the simulated profiles build part of the database for the first clinical treatment planning system for helium ions. The evolution of beamwidth was also compared to similar simulations of the clinically available proton and carbon beam. This allows a choice of treatment modality based on quantitative estimates of the physical beam properties. Finally, we investigated the influence of beamwidth variation on patient treatment plans in order to estimate the relevance and necessary precision limits for lateral beam width models.

Fabrication and properties of the He+-implanted K9 glass waveguide

This work reports on the fabrication and characterization of a K9 glass planar waveguide structure. The helium ion implantation was employed to form the waveguide on the K9 glass. The choices of the energy of 0.4 MeV and the dose of [Formula: see text] ions/cm2 were conducted by the SRIM 2013. The [Formula: see text]-line spectroscopy and the modal profile of the He[Formula: see text]-irradiated K9 glass waveguide were performed by the prism-coupling system and the end-face coupling technique at 0.6328 [Formula: see text]m, which suggests the capability of light propagation. The He[Formula: see text]-implanted K9 glass waveguides can serve as potential candidates for advanced integrated optoelectronic devices.

Evaluation of the surface quality of spun materials using topothesy

Topothesy and fractal dimensions were calculated for poly(acrylonitrile) (PAN) nanofibers mats obtained by electrospinning. These methods enable quantitatively describing and thus comparing solid-state surfaces and detecting fabric errors. The obtained variety of structural properties results from different substrates and after-treatments, e.g. stabilization and carbonization. The change in spatial morphology was reported for different magnification of images obtained with the use of Helium Ion Microscopy (HIM).

Numerical study of silicon vacancy color centers in silicon carbide by helium ion implantation and subsequent annealing

Molecular dynamics (MD) simulation is adopted to discover the underlying mechanism of silicon vacancy color center and damage evolution during helium ions implanted four-hexagonal silicon carbide (4H-SiC) and subsequent annealing. The atomic-scale mechanism of silicon vacancy color centers in the process of He ion implantation into 4H-SiC can be described more accurately by incorporating electron stopping power for He ion implantation. We present a new method for calculating the silicon vacancy color center numerically, which considers the structure around the color center and makes the statistical results more accurate than the Wigner-Seitz defect analysis method. At the same time, photoluminescence (PL) spectroscopy of silicon vacancy color center under different helium ion doses is also characterized for validating the numerical analysis. The MD simulation of the optimal annealing temperature of silicon vacancy color center is predicted by the proposed new method.

Tailoring interfacial effect in multilayers with Dzyaloshinskii–Moriya interaction by helium ion irradiation

We show a method to control magnetic interfacial effects in multilayers with Dzyaloshinskii–Moriya interaction (DMI) using helium (He$$^{+}$$ + ) ion irradiation. We report results from SQUID magnetometry, ferromagnetic resonance as well as Brillouin light scattering results on multilayers with DMI as a function of irradiation fluence to study the effect of irradiation on the magnetic properties of the multilayers. Our results show clear evidence of the He$$^{+}$$ + irradiation effects on the magnetic properties which is consistent with interface modification due to the effects of the He$$^{+}$$ + irradiation. This external degree of freedom offers promising perspectives to further improve the control of magnetic skyrmions in multilayers, that could push them towards integration in future technologies.

An intra-cytoplasmic route for SARS-CoV-2 transmission unveiled by Helium-ion microscopy

SARS-CoV-2 virions enter the host cells by docking their spike glycoproteins to the membrane-bound Angiotensin Converting Enzyme 2. After intracellular assembly, the newly formed virions are released from the infected cells to propagate the infection, using the extra-cytoplasmic ACE2 docking mechanism. However, the molecular events underpinning SARS-CoV-2 transmission between host cells are not fully understood. Here, we report the findings of a scanning Helium-ion microscopy study performed on Vero E6 cells infected with mNeonGreen-expressing SARS-CoV-2. Our data reveal, with unprecedented resolution, the presence of: 1)-long tunneling nanotubes that connect two or more host cells over submillimeter distances; 2)-large scale multiple cell fusion events (syncytia); and 3)-abundant extracellular vesicles of various sizes. Taken together, these ultrastructural features describe a novel intra-cytoplasmic connection among SARS-CoV-2 infected cells that may act as an alternative route of viral transmission, disengaged from the well-known extra-cytoplasmic ACE2 docking mechanism. Our findings may explain the elusiveness of SARS-CoV-2 to survive from the immune surveillance of the infected host.