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Monitoring the Coldhead of Magnetic Resonance Imaging Systems by Means of Vibration Analysis

Journal of Sensor Technology 2017年第3期7卷 39-51页

作者： jan beyer Johannes Krug Michael Friebe Department for Medical Engineering Otto-von-Guericke-University Magdeburg Magdeburg Germany

Magnetic resonance imaging (MRI) systems require a cooling close to the absolute zero point. This is necessary to avoid thermal losses due to the extremely high currents in the coils of the electromagnet used to generate the static magnetic field. The cooling is usually achieved using helium based refrigerating machine. The coldhead is an important and critical mechanical component in this system. An inefficient or failed coldhead can lead to severe damages to the MRI system or to the loss of helium. Hence, a continuous and reliable monitoring of this system component is necessary but not always available. To tackle this problem, we propose a monitoring system by means of analyzing the structure-borne noises caused by the mechanical activities of the coldhead. For this purpose, a measurement system based on piezoelectric elements was designed and implemented. Vibrations were measured at various locations at the MRI scanner with and without MR imaging. In all positions, the function of the coldhead could be detected. Hence, the developed system is suitable for monitoring an MRI’s coldhead without directly accessing the MR scanner’s hardware or software. For a future long-term monitoring, the aim is to predict a failure of the MRI’s coldhead based on changes in the vibrations signals.

关键词： Machine Monitoring Magnetic Resonance Imaging Piezoelectric Sensors Vibrations

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Extreme biomimetic approach for developing novel chitin-GeO2 nanocomposites with photoluminescent properties

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Nano Research 2015年第7期8卷 2288-2301页

作者： Marcin Wysokowski Mykhailo Motylenko jan beyer Anna Makarova Hartmut Stocker Juliane Walter Roberta Galli Sabine Kaiser Denis Vyalikh Vasilii V. Bazhenov laroslav Petrenko Allison L Stelling Serguei L. Molodtsovs Dawid Stawski Krzysztof J.Kurzydfowski Enrico Langer Mikhail V Tsurkan Teofil Jesionowski Johannes Heitmann Dirk C. Meyer Hermann Ehrlich Institute of Chemical Technology and Engineering Poznan University of Technology 60965 Poznan Poland Institute of Materials Science TU Bergakademie Freiberg 09599 Freiberg Germany Institute of Applied Physics TU Bergakademie Freiberg 09599 Freiberg Germany Institute of Solid State Physics Dresden University of Technology 01069 Dresden Germany Institute of Experimental Physics TU Bergakademie Freiberg 09599 Freiberg Germany Faculty of Medicine Carl Gustav Carus Department of Anaesthesiology and Intensive Care Medicine Clinical Sensoring and Monitoring TU Dresden 01069 Dresden Germany epartment of Physics St. Petersburg State University 198504 St. Petersburg Russia Department of Mechanical Engineering and Materials Science Duke University 27708 Durham NC USA European X-Ray Free-Electron Laser Facility (XFEL) GmbH 22761 Hamburg Germany ITMO University 197101 St. Petersburg Russia Department of Commodity and Material Sciences and Textile Metrology Technical University of Lodz 90924 LSdz Poland Materials Design Group Faculty of Materials Science and Engineering Warsaw University of Technology PL-02507 Warsaw Poland Institute of Semiconductors and Microsystems TU Dresden 01062 Dresden Germany Leibniz Institute of Polymer Research Max Bergmann Centre for Biomaterials 01062 Dresden Germany

This work presents an extreme biomimetics route for the creation of nano- structured biocomposites utilizing a chitinous template of poriferan origin. The specific thermal stability of the nanostructured chitinous template allowed for the formation under hydrothermal conditions of a novel germanium oxide- chitin composite with a defined nanoscale structure. Using a variety of analytical techniques （FTIR, Raman, energy dispersive X-ray （EDX）, near-edge X-ray absorption fine structure （NEXAFS）, and photoluminescence （PL） spectroscopy, EDS-mapping, selected area for the electron diffraction pattern （SAEDP）, and transmission electron microscopy （TEM））, we showed that this bioorganic scaffold induces the growth of GeO2 nanocrystals with a narrow （150-300 nm） size distri- bution and predominantly hexagonal phase, demonstrating the chitin template＇s control over the crystal morphology. The formed GeO2-chitin composite showed several specific physical properties, such as a striking enhancement in photo- luminescence exceeding values previously reported in GeOR-based biomaterials. These data demonstrate the potential of extreme biomimetics for developing new-generation nanostructured materials.

关键词： extreme biomimetics, chitin-GeO2 photoluminescence, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy

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