Self-oscillations in an active loop consisting of a wide-band amplifier and a magnetoelectric composite in the feedback circuit have been observed. The composite with a ferroelectric lead zirconate titanate bimorph and ferromagnetic Metglas serves as a resonator that determines the frequency of oscillations and provides the feedback voltage. Under amplitude balance and phase matching conditions, the device generated signals at 2.3 kHz, at the bending resonance frequency of the composite. The oscillations were observed over a specific range of magnetic bias H. The shape of the signal generated is dependent on electrical circuit parameters and magnitude and orientation of H.
Matrix metalloproteinases belong to the key molecules of tissue remodeling involved in physiological and pathological processes of the female reproductive system. Adequate levels of their expression in the endometrium are essential for effective implantation and uneventful pregnancy. Chronic inflammatory process in the endometrium is associated with low tissue expression of metalloproteinase-9. Histologically verified chronic endometritis is associated with low serum activities of metalloproteinases 2 and 9, which are restored after combined etiotropic therapy. We measured serum levels of metalloproteinases in patients with chronic endometritis concomitant with sterility and its changes during the first days after magnetotherapy.
A multiferroic magnetic field sensor capable of producing an output for threshold magnetic fields has been fabricated and characterized. The sensor consists of a trilayer composite of piezoelectric X-cut lanthanum gallium tantalate and magnetostrictive Metglas placed inside a solenoid and a wide-band amplifier. The composite plays two distinct roles in the device; it forms the feedback loop of an oscillator and sets the frequency of sustained oscillations. The sensor generated an output of 2.5 V at the longitudinal acoustic resonance frequency of 87.5 kHz for the trilayer for DC magnetic fields H = 0.3 to 50 Oe parallel to the composite plane. The device functions as a threshold magnetic field sensor for this H-interval, and the threshold ON and OFF H-values for an ac voltage output could be controlled electronically or with a proper choice of the ferromagnetic phase in the composite.
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