Publications by authors named "Baris Bayram"

Objective: We investigated the effect of Remote Ischemic Preconditioning (RIPC) on the inflammatory response during CPB by means of serum presepsin levels at preoperative and postoperative 1st and 24th h.

Methods: In this prospective, randomized, cross-sectional study we included 81 patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass (CPB). Patients were randomized and RIPC was applied to 40 patients in the study group before anesthesia.

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Objectives: The current study aims to report midterm results of patients treated with endovascular intervention, kissing stent, or covered endovascular reconstruction of the aortic bifurcation, for Trans-Atlantic Inter-Society Consensus C or D aortoiliac occlusive disease involving the aortic bifurcation.

Methods: Eighteen patients who have intermittent claudication or chronic limb threatening ischemia with Trans-Atlantic Inter-Society Consensus C or D aortoiliac occlusive disease involving the aortic bifurcation enrolled to the study between January 2018 and January 2021. Kissing stents, Advanta V12 (Atrium, Getinge Group), were used in 13 patients, and the covered endovascular reconstruction of the aortic bifurcation technique was used in 4 patients to reconstruct the aortic bifurcation.

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Background: The objective of this study was to investigate the inflammatory effects of different oxygenator flow pattern types in patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass.

Methods: We designed this randomized, single-blind, prospective study of patients with coronary artery disease. We compared the systemic inflammatory effects of oxygenators with two types of flow: axial flow and radial flow.

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Acoustic scene analysis (ASA) relies on the dynamic sensing and understanding of stationary and non-stationary sounds from various events, background noises and human actions with objects. However, the spatio-temporal nature of the sound signals may not be stationary, and novel events may exist that eventually deteriorate the performance of the analysis. In this study, a self-learning-based ASA for acoustic event recognition (AER) is presented to detect and incrementally learn novel acoustic events by tackling catastrophic forgetting.

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In this study, radiation impedance of a capacitive micromachined ultrasonic transducer composed of square-shaped membranes arranged in m × m configuration (m = 1 - 5) is investigated using finite element analysis (FEA) of a commercially available software package(ANSYS). Radiation impedance is calculated for immersed membranes operating in conventional and collapse modes. Individual membrane response within the multi-membrane configuration is analyzed, and excited modes and their effects on radiation impedance and the pressure spectra are reported.

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Diamond is a superior membrane material for capacitive micromachined ultrasonic transducers (CMUTs). By using ultrananocrystalline diamond (UNCD) membrane and plasma-activated wafer bonding technology, a single diamond-based circular CMUT is demonstrated and operated in immersion for the first time. The diamond-based CMUT, biased at 100 V, is excited with a 10-cycle burst of 36 V(p-p) sine signal at 3.

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Crosstalk is the coupling of energy between the elements of an ultrasonic transducer array. This coupling degrades the performance of transducers in applications such as medical imaging and therapeutics. In this paper, we present an experimental demonstration of guided interface waves in capacitive micromachined ultrasonic transducers (CMUTs).

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We report experimental results from a comparative study on collapsed region and conventional region operation of capacitive micromachined ultrasonic transducers (CMUTs) fabricated with a wafer bonding technique. Using ultrasonic pulse-echo and pitch-catch measurements, we characterized single elements of 1-D CMUT arrays operating in oil. The experimental results from this study agreed with the simulation results: a CMUT operating in the collapsed region produced a higher maximum output pressure than a CMUT operated in the conventional region at 90% of its collapse voltage (3 kPa/V vs.

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This paper reports on the experimental characterization of collapse-mode operation of capacitive micromachined ultrasonic transducers (CMUTs). CMUTs are conventionally operated by applying a direct current (DC) bias voltage less than the collapse voltage of the membrane, so that the membrane is deflected toward the bottom electrode. In the conventional regime, there is no contact between the membrane and the substrate; the maximum alternating current (AC) displacement occurs at the center of the membrane.

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Electrostatic transducers are usually operated under a DC bias below their collapse voltage. The same scheme has been adopted for capacitive micromachined ultrasonic transducers (cMUTs). DC bias deflects the cMUT membranes toward the substrate, so that their centers are free to move during both receive and transmit operations.

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Article Synopsis
  • cMUTs, or capacitive micromachined ultrasonic transducers, were designed to enhance efficiency in the ultrasonic industry by operating near the collapse voltage.
  • The proposed collapse-snapback method allows for improved acoustic output pressures by collapsing the membrane onto the substrate and then releasing it, utilizing a broader range of membrane deflection profiles.
  • Key design factors like electrode radius and membrane thickness were optimized through finite element calculations to maximize displacement per cycle and improve performance in high-power transmission applications.
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We report on a new operation regime for capacitive micromachined ultrasonic transducers (cMUTs). Traditionally, cMUTs are operated at a bias voltage lower than the collapse voltage of their membranes. In the new proposed operation regime, first the cMUT is biased past the collapse voltage.

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The electromechanical coupling coefficient is an important figure of merit of ultrasonic transducers. The transducer bandwidth is determined by the electromechanical coupling efficiency. The coupling coefficient is, by definition, the ratio of delivered mechanical energy to the stored total energy in the transducer.

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