An analytical treatment of the piezoelectric ceramic complete ring transducer undergoing flexural vibrations is presented. Conditions for the electromechanical excitation of the flexural vibrations are discussed and it is shown that the fundamental mode of the flexural vibration of a complete ring can be considered as sufficiently dominant over a broad frequency range. Hence, the one-dimensional equivalent electromechanical circuit representation of the transducer is applicable and all the parameters of the equivalent circuit are determined. Possibilities to optimize the effective coupling coefficient of the transducer by changing the extent of the electrodes on the piezoelectric body are considered. It is shown that for effective operation of the flexural ring transducer as a low frequency hydroacoustic projector the opposing quadrants (or three quadrants in case of a planar array configuration) have to be covered with baffles. The radiation impedance and directional factors of the transducers with baffles are considered. Limitations of the acoustical power radiated by the transducers are discussed.
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http://dx.doi.org/10.1121/1.4812760 | DOI Listing |
Environ Microbiol
January 2025
Faculty of Biology-Microbiology, University of Freiburg, Freiburg, Germany.
Bacterial degradation of ubiquitous and persistent steroids such as steroid hormones is important for their removal from the environment. Initial studies of steroid degradation in anaerobic bacteria suggested that ring-cleaving hydrolases are involved in oxygen-independent sterane skeleton degradation. However, the enzymes involved in ring A cleavage of the common intermediate androsta-1,4-diene-3,17-dione have remained unknown.
View Article and Find Full Text PDFAME Case Rep
November 2024
Department of Orthopaedic Surgery, Sugita Genpaku Memorial Obama Municipal Hospital, Fukui, Japan.
Background: Open pelvic fractures are rare but represent a serious clinical problem with high mortality rates. Acute mortality is often associated with hemorrhage, whereas delayed mortality is most often associated with sepsis and multiple organ failure. We report a case of Wang's classification of type II open pelvic ring fracture with hemorrhagic shock and septic shock from gas gangrene.
View Article and Find Full Text PDFAME Case Rep
November 2024
Hebei Key Laboratory of Cancer Radiotherapy and Chemotherapy, Department of Medical Oncology, Affiliated Hospital of Hebei University, Baoding, China.
Background: Mucinous adenocarcinoma is a rare type of colorectal cancer (CRC) associated with poor prognosis, particularly when it includes signet ring cell components. Furthermore, its rate of microsatellite instability-high (MSI-H) is significantly higher compared to non-mucinous adenocarcinoma. Immunotherapy has emerged as the standard treatment for MSI-H metastatic CRC (mCRC).
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Institute of Physics, Lodz University of Technology, ul. Wólczańska 217/221, 93-590 Łódź, Poland.
Photocycloreversion reactions of three diarylethene derivatives whose structures differ only in the placement of two sulfur atoms in the cyclopentene rings are investigated. Despite the minuscule differences between the molecules, both the yields and times of the photoreactions vary considerably. Using UV-vis and infrared femtosecond spectroscopy and quantum chemical dynamics simulations, we elucidate the relationships among the quantum yield, electronic and vibrational relaxation time, and structural properties of the dithienylethene photoswitches.
View Article and Find Full Text PDFMagn Reson Chem
January 2025
Laboratório de Química Computacional e Modelagem Molecular (LQC-MM), Departamento de Química Inorgânica, Instituto de Química, Universidade Federal Fluminense (UFF), Niterói, Rio de Janeiro, Brazil.
We present a DFT-PCM NMR study of 3-indoleacetic acid (3-IAA), used as a working example, including explicit solvent molecules, named PCM-nCHCl, PCM-nDMSO (n = 0, 2, 4, 8, 14, 20, and 25), to investigate the dimer formation in solution. Apart from well-known cyclic (I) and open (II) acetic acid (AA) dimers, two new structures were located on DFT-PCM potential energy surface (PES) for 3-IAA named quasicyclic A (III) and quasicyclic B (IV), the last one having N-H…O hydrogen bond (instead of O-H…O). In addition, four other structures having π-π type interactions named V, VI, VII, and VIII were also obtained completing the sample on the PES.
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