Query: magnetic field and Catalase

title: SPATIAL MAGNETIC FIELD CALCULATIONS FOR CORELESS CIRCULAR COILS WITH RECTANGULAR CROSS SECTION OF ARBITRARY TURN NUMBERS
abstract: In a wireless magnetic induction communication system, the magnetic field distribution of the current carrying coil affects the communication effect between the communication transceiver and receiver. In the study of magnetic field distribution, it was found that magnetic induction intensity and magnetic flux were important parameters to measure the effectiveness of communication. Aiming at the circular coils with rectangular cross section of any turn numbers, this paper proposed an improved algorithm to calculate the magnetic induction intensity at any spatial position based on Biot Savart law. At the same time, the calculation formula of the magnetic flux at the receiving point was also given. The coils were modeled and simulated with COMSOL software. The correctness of the improved algorithm was verified and compared with the traditional formula and simulation results, especially in the near field, which provided an important theoretical support for the further study of mutual inductance in the wireless magnetic induction communication system.

title: ANTENNA USING A MAGNETIC SLAB LOCATED IN THE PRINCIPAL MAGNETIC FIELD REGION BENEATH THE PATCH
abstract: This paper presents an analysis of microstrip patch antennas with different dielectric/magnetic substrate profiles in an attempt to obtain operating frequency reduction. Initially, different ridge shapes in the substrate were examined. An in depth investigation of the ridge shape and its dimensions on the antenna performance has been carried out. Subsequently an antenna with a magneticslab loaded in the prime magnetic field region beneath the patch is proposed. The new magnetic loaded antenna design is aimed to reduce the resonant frequency of a conventional patch and reduce the profile of an earlier design with a substrate ridge. Various magnetic materials have been embedded within the original dielectric substrate of the patch antenna. Measured results validated the hypothesis that this frequency can be reduced by placing magnetic materials at the centre of the patch. The achieved gain is expected to be further enhanced by using forthcoming magnetic materials with improved performance.

title: Progress in miniaturization and low field nuclear magnetic resonance.
abstract: In this paper, we review the latest developments in miniaturization of NMR systems with an emphasis on low field NMR. We briefly cover the topics of magnet and coil miniaturization, elaborating on the advantages and disadvantages of miniaturized coils for different applications. The main part of the article is dedicated to progress in NMR electronics. Here, we touch upon software defined radios as an emerging gadget for NMR before we provide a detailed discussion of NMR on a chip transceivers as the ultimate solution in terms of miniaturization of NMR electronics. In addition to discussing the miniaturization capabilities of the NMR on a chip approach, we also investigate the potential use of NMR on a chip devices for an improved NMR system performance. Here, we also discuss the possibility of combining the NMR on a chip approach with EPR on a chip spectrometers to form compact DNP on a chip systems that can provide a significant sensitivity boost, especially for low field NMR systems.

title: Magnetic background field tolerant SQIF based current sensors
abstract: We report on the development of magnetic background field tolerant superconducting quantum interference filter (SQIF) based on low capacitance sub micrometer sized cross type Josephson junctions either as current sensing amplifiers even on chip for advanced superconducting quantum interference device (SQUID) readout circuits or as magnetic field sensor in flux transformer configuration especially for geophysical measurement systems. Their very small parasitic magnetic sensitive areas enable them to operate in the Earth magnetic field and allow for magnetically unshielded cool down. The careful consideration of magnetic sensitive areas inside each SQUID in the SQIF in all three dimensions result in developed SQIFs with 28 SQUIDs in series exhibiting large voltage swing and transfer function of more than 2 mV and 500VA 1 respectively. We report on the electrical parameters and field stability as well as on the noise performance of the devices under investigation. SQIFs and devices with additional on chip flux transformers show input referred current noise levels of 5.9 and 1.1pAHz 1/2 respectively. We furthermore demonstrate their potential as SQIF based magnetometers using them in addition with thin film pickup loops resulting in a white magnetic field noise of 1.6fTHz 1/2 The implemented SQIFs are thus highly compatible with state of the art single SQUID devices offering beneficial features such as a unique working point, making them excellent suited for implementation of e.g. geophysical instruments.

title: Facile synthesis of magnetic hierarchical flower like Co3O4 spheres: Mechanism, excellent tetra enzyme mimics and their colorimetric biosensing applications.
abstract: Magnetic hierarchical flower like Co3O4 spheres (Co3O4 nanoflowers) were facilely prepared via one step surfactant free and template free wet chemical route at room temperature. The formation mechanism of Co3O4 nanoflowers was explored. The as prepared Co3O4 nanoflowers exhibited excellent tetra enzyme mimetic activities, including oxidase like, peroxidase like, catalase like and superoxide dismutase (SOD) like activity. The catalytic mechanism of the Co3O4 nanoflowers was studied in detail. The oxidase like catalytic activity of Co3O4 nanoflowers was derived from the inherent oxygen vacancies of Co3O4, while the peroxidase like catalytic activity originated from the *OH radical generated by hydrogen peroxide (H2O2) Only one specific enzyme mimics reaction with Co3O4 nanoflowers can be obtained by inhibiting specifically other nanozymes via varying pH, adding appropriate scavengers or selecting its specific substrate. Further, the steady state kinetic and catalytic performance of the oxidase peroxidase and catalase mimics of Co3O4 nanoflowers were studied. Based on the oxidase like and peroxidase like activities of Co3O4 nanoflowers, bifunctional colorimetric sensing platforms were constructed for the sensitive detection of acid phosphatase (ACP) with the linear range of 0.1 25 U L 1 and H2O2 with the linear range of 4 400 mM. Further, it is capable of detecting ACP in serum samples and H2O2 in water samples, respectively. Thus, the tetra enzyme mimetic Co3O4 nanoflowers show broad prospects in the fields of biosensors, tumor therapy, environmental monitoring and biocatalysis.

title: Oxidative stress associated with long term occupational exposure to extremely low frequency electric and magnetic fields.
abstract: Occupational exposure to extremely low frequency electromagnetic fields (ELF EMFs) may have harmful effects on biologic systems and has raised many concerns in the last decades.  The aim of this study was to determine the effects of exposure to extremely low frequency electric and magnetic fields on lipid peroxidation and antioxidant enzyme activities.  This study was conducted on 115 power plant workers as the exposed group and 145 office workers as the non exposed group. The levels of Malondialdehyde (MDA) Superoxide Dismutase (SOD) Catalase (Cat) and Total Antioxidant Capacity (TAC) were measured in the serum of all subjects. Exposure to ELF EMFs was measured based on spot measurements and the IEEE Std C95.3.1 standard.  The levels of MDA, SOD, and Cat in the exposed group were significantly higher than in the non exposed group. However, the level of TAC was not significantly different between the exposed (2.45+ 1.02) and non exposed (2.21+ 1.07) groups. The levels of MDA and SOD were higher among workers with higher exposure to electric fields than workers with low exposure. All oxidative stress indicators increased with increased exposure to magnetic fields, except TAC.  The antioxidant system imbalance among power plant workers may be related to long term occupational exposure to electromagnetic fields.

title: Magnetic softness, dynamic magnetization, and relaxation behavior of FeSiBC amorphous alloys
abstract: The variation of dynamic coercivity, core loss, permeability m and relaxation behavior with annealing temperature, frequency as well as magnetic field magnitude H m for the FeSiBC amorphous alloy was systematically studied. It can be found that the dynamic coercivity H cd of 6.2 A/m at 1.0 T and 50 Hz is much larger than the static coercivity H cs of 1.7 A/m for the optimally annealed Fe 78 Si 8 B 13 C 1 alloy. The increase of H cd with the increases in frequency can be ascribed to the difficulty of domain wall motion and magnetization rotation as frequency elevates. The dynamic magnetization analysis reveals that m goes up and attains a peak value as H m increases to about 25 A/m in the low frequency range, while the m does not depend on H m in the high frequency range f 10 kHz) In addition, the change of magnetic relaxation time with annealing temperature and filed magnitude is discussed.

title: High latitude crochet: solar flare induced magnetic disturbance independent from low latitude
abstract: Solar flare induced High latitude (peak at 70 75* geographic latitude) ionospheric current system was studied. Right after the X9.3 flare on 6 September 2017, magnetic stations at 68 77* geographic latitudes (GGlat) near local noon detected northward geomagnetic deviations (B) for more than 3 hours, with peak amplitudes >200 nT, without any accompanying substorm activities. From its location, this solar flare effect, or crochet, is different from previously studied ones, namely, subsolar crochet (seen at lower latitude) auroral crochet (pre requires auroral electrojet in sunlight) or cusp crochet (seen only 5 in the cusp) The new crochet is much more intense and longer in duration than the subsolar crochet. The long duration matches with the period of high solar X ray flux (more than M3 class flare level) Unlike the cusp crochet, interplanetary magnetic field (IMF) BY is not the driver with BY only 0 1 nT out of 3 nT total field. The equivalent ionospheric current flows eastward in a limited latitude range but extended at least 8 hours in local time (LT) forming a zonal current region equatorward of the polar cap on the geomagnetic closed region. 10 EISCAT radar measurements over the same region as the most intense B near local noon show enhancements of electron density (and hence ion neutral ratio) at these altitudes 100 km) where the background Sq ion convection 100 m/s) preexisted. Therefore, this new zonal current can be related to the Sq convection and the electron density enhancement, e.g. by descending E region height. However, we have not found why the new crochet is found in a limited latitudinal range, and therefore the mechanism is still unclear compared to the subsolar crochet that is maintained by transient re distribution of 15 electron density. The signature is sometimes seen in the Auroral Electrojet (AE) index. A quick eye survey for X class flares during solar cycle 23 and 24 shows clear AU increases for about half the >X2 flares during non substorm time, although the latitudinal coverage of the AE stations is not favorable to detect this new crochet. Although some of them could be due to auroral crochet, this new crochet can be rather common feature for X flares. 20 key points (1) We found a new type of the solar flare effect on the dayside ionospheric current at high latitudes but equatorward of the cusp during quiet periods. 1 https:/doi.org/10.5194/angeo 2020 48   9 July 2020 c (c) Author(s) 2020. CC BY 4.0 License.

title: Feasibility of Glutamate and GABA Detection in Pons and Thalamus at 3T and 7T by Proton Magnetic Resonance Spectroscopy
abstract: Glutamate detection in pons and thalamus using proton magnetic resonance spectroscopy (1H MRS) after an intervention is of interest for studying various brain disorders. However, 1H MRS in these brain regions is challenging and time consuming, especially in longitudinal study designs. 1H MRS of more cortical structures at the ultrahigh magnetic field strength of 7T yields an improved spectral output, including separation of the glutamate signal from the glutamine signal, in a shorter and more feasible scan time, as compared to conventional clinical field strengths. For this purpose, we compared the feasibility of 1H MRS at 3T and 7T in pons and thalamus by applying a longitudinal study design of repeated measures on same day and three separate days at both field strength in five healthy participants. Total 1H MRS acquisition time was reduced by a factor 3.75 for pons and by a factor 3 for thalamus at 7T as compared to 3T. We found higher spectral signal to noise ratio (SNR) (p 0.001) lower linewidth (p 0.001) and lower Cramer Rao lower bounds (CRLB) (p 0.001) for the combined glutamate and glutamine signal (Glx) in thalamus at 7T as compared to 3T. In pons, CRLB of Glx and SNR were lower at 7T (p 0.002 and p 0.006) with no differences in linewidth compared to 3T. Mean within subject variability of Glx concentration estimates was lower at 7T compared to 3T for both pons and thalamus. At 7T, it was possible to assess glutamate and g aminobutyric acid (GABA) simultaneously in pons and thalamus. In conclusion, 1H MRS at 7T resulted in improved spectral quality while allowing shorter scan times than at 3T as well as estimation of the pure glutamate signal in pons and thalamus. This opens up the opportunity for multimodal study designs and multiregional subcortical 1H MRS research. Glutamate and GABA measurement at 7T in pons and thalamus is advantageous for future investigations of excitatory inhibitory mechanisms in brain disorders.

title: Comparison of Superconductors and Permanent Magnets for Small scale Magnetic Resonance Imaging Devices
abstract: In this feasibility study, we use finite element method simulations to compare superconductors (SC) coils and permanent magnets (PM) assemblies as main field source for a small scale magnetic resonance imaging scanner. The motivation behind this investigation is that for certain tissues, e.g. knee ligament, diagnosis can be performed with equipment operating with relatively weak magnetic fields. It is then interesting to assess whether the relaxed field requirement enables alternative technologies, which present some advantages over the well established helium cooled low temperature superconductors. As prototypical magnetic systems, we consider the Helmholtz coil and the Halbach cylinder for the SC and PM cases, respectively. Each possibility is simulated over a wide range of combinations of the fundamental design parameters. We estimate field strength, field homogeneity, and total cost over the service life of the device. From these figures of merit, we evaluate the optimal combinations of design parameters. Finally, we compare the SC and PM systems and we establish the range of field requirement values for which one alternative is more suitable than the other one. The result of the present investigation provides the starting point for more detailed studies where more specific design considerations are taken into account.