Browsing by Author "Dogan, Mustafa"

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Aligned Polyvinylpyrrolidone Nanofibers with Advanced Electrospinning for Biomedical Applications
(2018) Karayegen, Gokay; Kocum, I. Cengiz; Serdaroglu, Dilek Cokeliler; Dogan, Mustafa; 0000-0001-5215-8887; 30400080; I-4296-2019
BACKGROUND: Electrospinning is a highly effective method in order to generate nano-scaled fibers. In conventional electrospinning technique, geometry of nanofibers are mostly random due to the chaotic behavior of polymer jet. OBJECTIVE: Purpose of this study is to produce aligned nanofibers from PVP polymers with advanced electrospinning technique in order to be used in a potential novel sensor applications, tissue regeneration and engineering. METHODS: In this study, by using finite hollow cylinder focusing electrodes, an external electrostatic field is created. With these electrodes, it is aimed to decrease whipping instability of polymer jet. In addition, it is also investigated that the alignment ratio of nanofibers by using conductive parallel electrodes which placed through jet trajectory. RESULTS: In conclusion, with the effect of electrical field created by cylinder electrodes, radius of the fiber dispersion on the collector was able to be reduced and aligned nanofibers were successfully produced by using electrical field generated from the parallel plates. CONCLUSIONS: Radius of the fiber dispersion on the collector is 9.95 mm and fiber diameters varied between 800 nm and 3 mu m. Additionally, alignment ratio of the fibers is determined with ImageJ software. These alignment of nanofibers can be used in tissue engineering applications and sensor applications.
An Alternative Electrospinning Approach With Varying Electric Field for 2-D-Aligned Nanofibers
(2014) Karatay, Okan; Dogan, Mustafa; Uyar, Tansel; Cokeliler, Dilek; Kocum, Ismail Cengiz; U-7861-2018
In the electrospinning process, unstructured nanofiber mats are produced by oriented fluid jets with an external electrostatic field. Electrospun fibers have wide applications for the fabrication of composite materials, tissue scaffold, and membranes. However, electrospun fiber production systems have many problems, e. g., the bending instability due to the complicated oscillations of polymer jet. In this research, parallel plate and hollow cylindrical conducting electrodes are implemented through the jet trajectory in order to investigate the possibility of controlled deposition of polymer fibers. Parallel electrodes with proper driving sources can generate the steering field for the nanofiber formation at the collector plate based on analog addressing electronics. It was shown that the modulated electric field applied through the parallel plate electrodes notably increased the deposition of the electrospun polymer fibers in a controlled fashion at the collector, which is coherent to the computer simulations. Furthermore, the finite-length hollow cylinder dampened the bending instabilities of the polymer jet which decreases the characteristic spot size of the deposited electrospun fiber to a smaller diameter.
Design and Implementation of An Identifier System for Inter-Area Power Oscillations
(2015) Atalika, Tevhid; Dogan, Mustafa; Demirci, Turan; 0000-0001-5215-8887; I-4296-2019
Identifying inter-area oscillations can be a challenge for interconnected grids. Two identifier algorithms (FBMSWA and TBR-EMD) proposed to detect these oscillations are comparatively tested in this research. FBMSWA is implemented with T-STATCOM to damp out 0.15 Hz low-frequency inter-area oscillation after interconnection Turkey with ENTSO-E. Developed TBR-EMD algorithm has certain achievements, e.g. admissible for real time, handling intermittency problem of EMD, proved by real data. (C) 2015 Elsevier B.V. All rights reserved.
Effective Sensor Fusion of a Mobile Robot for SLAM Implementation
(2018) Toroslu, Irem; Dogan, Mustafa
The Simultaneous Localization and Mapping (SLAM) is the process of building a map of an environment with an unknown topography by a mobile robot. The purpose of this paper is to build a mapping of an unknown environment by the mobile robot which we designed through the help of sensor fusion algorithms we have established. The mobile robot performs its mapping process by using the combination of ultrasonic, optical encoder and IMU sensors. Determining the position of the obstacles and its own location, for the mobile robot, is the core of this study. Inertial and rotational sensors are utilized to calculate the distance and position of the mobile robot. Due to low cost, the ultrasonic sensor is used instead of a Lidar laser, and the real-like results were provided. In this study, the robot's direction and movement is performed by an algorithm developed on the Raspberry Pi processor. This algorithm controls the movement of the wheels with the information received from the optical encoder and protractor. The data received from the gyroscope and the accelerometer is very affected from many external factors such as vibrational motion and the noise, eventhough, we used moving average filter and complementary filter to reduce the effect of the noise and measurement error problems. However, they still produce faulty results when calculating distance values. Therefore, the distance computation is carried out by using optical encoder instead of the accelerometer. The algorithm of the distance computation is written in Python programming language. In this study, it is established that the comparative usage of several detectors provide more accurate results. At the same time, the system is quite efficiently developed by using open structure software (Raspberry Pi, Linux etc.) and writing authentic libraries. The robot's coordinate information are combined under simulation medium by using Pygame library and by computing the coordinates of its location and the coordinates of the objects' locations it detects during its navigation. The mobile robot executes its mapping process according to these data derived. Also, the effects of margin of error in the information obtained during the comparable usage of detectors are studied within the scope of this study.
Efficient Energy Harvesting Systems for Vibration and Wireless Sensor Applications
(2017) Dogan, Mustafa; Inam, Sitki Cagdas; Surel, O. Orkun; 0000-0001-5215-8887; 0000-0003-0820-9186; I-4296-2019
In the first part of the research, we present the design of a vibration-based energy harvesting system. Robotic flexible arm having variable cross-section is investigated to overcome serious problems, e.g. insufficient bandwidth and model inaccuracies. Most of the energy harvesting systems are linear with unimodal characteristics. On the other hand, real vibrations can be modeled as random, multi-modal and time varying systems. Hence, unimodal linear systems can give highly unsatisfactory results under certain circumstances. However, non-linear systems can have multi-modal character with increased performance in real and practical situations. In this work, tapered links are preferred with nonlinear coupling setup to provide sufficient bandwidth and output power requirements for modern applications. Thus, the proposed scheme has been proven by simulated and experimental results successfully. In the second part of the research, we present design and experimental results of an electromagnetic harvester, energy source of which is single-phase household AC power with a nominal voltage of 220 V and a frequency of 50 Hz. In this case, energy harvesting is based on the induced electromotive force (EMF) as a result of the periodic variations of the magnetic field around the AC power cord. In this part, we also discuss basic principles of a wireless sensor network design powered by electromagnetically harvested energy obtained from household alternating current.
A New Modeling Approach for Stability of Micro/Nano Bubbles
(2021) Dogan, Mustafa; Bunyatova, Ulviya; Ferhanoglu, Onur
Microbubbles and nanobubbles have several characteristics that are comparable with millimeter- and centimeter-sized bubbles. These characteristics are their small size, which results in large surface area and high bioactivity, low rising velocity, decreased friction drag, high internal pressure, large gas dissolution capacity, negatively charged surface, and ability to be crushed and form free radicals. Controlling and modeling fundamental properties such as nucleation and of the dynamics of these bubbles is key to successfully exploiting their potential in the growing number of applications such as biomedical diagnosis and therapy, antimicrobial in aquaculture, environment, engineering, stock raising and marine industry. Laser-generated bubble dimensions can be characterized with an optical setup employing a high power continuous wave green laser for bubble generation. In this work, non-resonant, self-excited due to structurally nonlinear properties of the hydrogel, bubble formation was modeled as functions of well-controlled parameters of the colloidal media that is multi-layered and anisotropic, engineered uniquely. Copyright (C) 2021 The Authors.
The Roberts Syndrome: A Case Report of an Infant with Valvular Aortic Stenosis and Mutation in ESCO2
(2014) Dogan, Mustafa; Firinci, Fatih; Balci, Yasemin Isik; Zeybek, Selcan; Ozgurler, Funda; Erdogan, Ilkay; Varan, Birgul; Semerci, Cavidan Nur; https://orcid.org/0000-0002-6719-8563; 24864645; ABB-1767-2021
Roberts syndrome, which is inherited as an autosomal recessive group of disorders, is a rare syndrome characterized with symmetrical extremity defects, craniofacial abnormalities, and prenatal and postnatal growth retardation. Here, we present a case of Roberts Syndrome brought to the clinic with diarrhoea and multiple abnormalities, that had tetra phocomelia, growth and developmental retardation, abnormality of complete cleft lip-palate accompanied with Aortic stenosis and PDA, and in which cytogenetic analysis identified premature centromere separation. Mutation analysis of ESCO2 revealed a splice site mutation [c.1131+1G>A] in intron 6 in homozygous status in the patient and heterozygous status in the parents. Our case is the first Robert- Syndrome with valvular aortic stenosis in the literature, to the best of our knowledge.
A Systematic Analysis of the Gene and Variation Content of the Extended HLA Region
(2017) Kanbur, Ertan; Dogan, Mustafa; Dorak, Mehmet Tevfik
Treatment of ventilator-associated pneumonia (VAP) caused by Acinetobacter: results of prospective and multicenter ID-IRI study
(2020) Erdem, Hakan; Cag, Yasemin; Gencer, Serap; Uysal, Serhat; Karakurt, Zuhal; Harman, Rezan; Aslan, Emel; Mutlu-Yilmaz, Esmeray; Karabay, Oguz; Uygun, Yesim; Ulug, Mehmet; Tosun, Selma; Dogru, Arzu; Sener, Alper; Dogan, Mustafa; Hasbun, Rodrigo; Durmus, Gul; Turan, Hale; Batirel, Ayse; Duygu, Fazilet; Inan, Asuman; Akkoyunlu, Yasemin; Celebi, Guven; Ersoz, Gulden; Guven, Tumer; Dagli, Ozgur; Guler, Selma; Meric-Koc, Meliha; Oncu, Serkan; Rello, Jordi; 31502120
Ventilator-associated pneumonia (VAP) due to Acinetobacter spp. is one of the most common infections in the intensive care unit. Hence, we performed this prospective-observational multicenter study, and described the course and outcome of the disease. This study was performed in 24 centers between January 06, 2014, and December 02, 2016. The patients were evaluated at time of pneumonia diagnosis, when culture results were available, and at 72 h, at the 7th day, and finally at the 28th day of follow-up. Patients with coexistent infections were excluded and only those with a first VAP episode were enrolled. Logistic regression analysis was performed. A total of 177 patients were included; empiric antimicrobial therapy was appropriate (when the patient received at least one antibiotic that the infecting strain was ultimately shown to be susceptible) in only 69 (39%) patients. During the 28-day period, antibiotics were modified for side effects in 27 (15.2%) patients and renal dose adjustment was made in 38 (21.5%). Ultimately, 89 (50.3%) patients died. Predictors of mortality were creatinine level (OR, 1.84 (95% CI 1.279-2.657); p = 0.001), fever (OR, 0.663 (95% CI 0.454-0.967); p = 0.033), malignancy (OR, 7.095 (95% CI 2.142-23.500); p = 0.001), congestive heart failure (OR, 2.341 (95% CI 1.046-5.239); p = 0.038), appropriate empiric antimicrobial treatment (OR, 0.445 (95% CI 0.216-0.914); p = 0.027), and surgery in the last month (OR, 0.137 (95% CI 0.037-0.499); p = 0.003). Appropriate empiric antimicrobial treatment in VAP due to Acinetobacter spp. was associated with survival while renal injury and comorbid conditions increased mortality. Hence, early diagnosis and appropriate antibiotic therapy remain crucial to improve outcomes.