arXiv subjects

Meinhard Schilling

Publications and source records attributed to Meinhard Schilling.

4 recordsLinked to original sources

arXiv2025

YBa$_2$Cu$_3$O$_7$ nano-constriction Josephson junctions and SQUIDs fabricated by focused helium-ion-beam irradiation

By focused $30\,\mathrm{keV}$ He ion beam irradiation, epitaxially grown YBa$_2$Cu$_3$O$_7$ (YBCO) thin films can be driven from the superconducting to the insulating state with increasing irradiation dose. A properly chosen dose suppresses superconductivity down to $4\,\mathrm{K}$, while crystallinity is still preserved. With this approach we create areas of normal-conducting YBCO that can be used to define resistively shunted constriction-type Josephson junctions (cJJs) on the nanometer scale. We also demonstrate that the fabricated cJJs can be incorporated in direct current superconducting quantum interference devices and can be used as detector junctions in THz antennas.

cond-mat.supr-con↗

arXiv2022

Air quality monitoring survey in german school classrooms during the COVID-19 pandemic 2021

The air quality in classrooms across all types of schools in Lower Saxony in the north of Germany has been monitored during June to December 2021 in a large study. Novel sensor instruments for air quality monitoring were wall mounted in 329 rooms in 50 schools and day nurseries. Each sensor instrument records data for carbon dioxide CO$_2$, sound level, temperature, and humidity. All collected data are transmitted for monitoring and further statistical evaluation by WiFi connection to the database. This study provides for the first time a detailed survey of the air quality situation and handling in schools during more than six months. The situation can be characterized by large variety in classroom area and volume combined with very diverse air ventilation possibilities. To control virus transmission via aerosol in classrooms an individual monitoring of air quality combined with high compliance for ventilation according to the signaled recommendation is urgently required.

physics.med-ph↗

arXiv2021

Single Harmonic-based Narrowband Magnetic Particle Imaging

Visualization of the in vivo spatial distribution of superparamagnetic iron oxide nanoparticles (SPIONs) is crucial to biomedicine. Magnetic particle imaging (MPI) is one of the most promising approaches for direct measurements of the SPION distribution. In this paper, we systematically investigate a single-harmonic-based narrowband MPI approach. Herein, only the 3rd harmonic at 15 kHz of the SPION signal induced in an excitation magnetic field of 5 kHz is measured via a narrowband detection system for imaging during scanning a field-free-point in a field of view. Experiments on spot and line phantoms are performed to evaluate the spatial distribution by the assessment of the full width at half maximum and modulation transfer function at different excitation magnetic fields from 4 to 10 mT. Experimental results demonstrate that reconstructed images have a spatial resolution of 1.6 and 1.5 mm for a gradient field of 2.2 T/m and 4.4 T/m in x- and z-direction, respectively, at an excitation magnetic field of 4 mT. In terms of line gap, two lines with a gap of 0.5 mm are resolved. With increasing the excitation magnetic field to 10 mT, the spatial resolution gets worse to 2.4 and 2.0 mm in x- and z-direction, respectively. Moreover, the custom-built MPI scanner allows a limit of detection of 53 microgram (Fe)/mL (500 ng Fe weight) using perimag SPIONs. In addition, the excellent performance is demonstrated by imaging experiments on an "emg" logo phantom. We believe that the proposed narrowband MPI approach is a promising approach for SPION imaging.

physics.med-ph↗

arXiv2020

Rapid and sensitive detection of SARS-CoV-2 with functionalized magnetic nanoparticles

The outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) threatens global medical systems and economies, and rules our daily living life. Controlling the outbreak of SARS-CoV-2 has become one of the most important and urgent strategies throughout the whole world. As of October, 2020, there have not yet been any medicines or therapies to be effective against SARS-CoV-2. Thus, rapid and sensitive diagnostics is the most important measures to control the outbreak of SARS-CoV-2. Homogeneous biosensing based on magnetic nanoparticles (MNPs) is one of the most promising approaches for rapid and highly sensitive detection of biomolecules. This paper proposes an approach for rapid and sensitive detection of SARS-CoV-2 with functionalized MNPs via the measurement of their magnetic response in an ac magnetic field. Experimental results demonstrate that the proposed approach allows the rapid detection of mimic SARS-CoV-2 with a limit of detection of 0.084 nM (5.9 fmole). The proposed approach has great potential for designing a low-cost and point-of-care device for rapid and sensitive diagnostics of SARS-CoV-2.

physics.med-ph↗