Person: EKREN, NAZMİ
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EKREN
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NAZMİ
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Publication Open Access A drug-eluting nanofibrous hyaluronic acid-keratin mat for diabetic wound dressing(2022-01-01) EKREN, NAZMİ; GÜNDÜZ, OĞUZHAN; Su S., Bedir T., KALKANDELEN C., Sasmazel H. T. , Basar A. O. , Chen J., EKREN N., GÜNDÜZ O.© 2022, Qatar University and Springer Nature Switzerland AG.Diabetes mellitus is a chronic metabolic disease associated with long-term multisystem complications, among which are non-healing diabetic foot ulcers (DFUs). Electrospinning is a sophisticated technique for the preparation of polymeric nanofibers impregnated with drugs for wound healing, burns, and diabetic ulcers. This study describes the fabrication and characterization of a novel drug-eluting dressing made of core–shell structured hyaluronic acid (HA)–keratin (KR)-polyethylene oxide (PEO) and polycaprolactone (PCL) nanofibers to treat diabetic wounds. The core–shell nanofibers produced by the emulsion electrospinning technique provide loading of metformin hydrochloride (MH), HA, and KR in the core of nanofibers, which in return improves the sustained long term release of the drug and prolongs the bioactivity. Morphological and chemical properties of the fibers were examined by SEM, FTIR, and XRD studies. It was observed that the fibers which contain HA and KR showed thin fiber structure, greater swelling capacity, fast degradation and increased cumulative drug release amount than neat emulsion fibers due to the hydrophilic nature of HA and KR. MH showed a sustained release from all fiber samples over 20 days and followed the first-order and Higuchi model kinetics and Fickian diffusion mechanism according to kinetic analysis results. In vitro cell culture studies showed that the developed mats exhibited enhanced biocompatibility performance with HA and KR incorporation. The results show that HA and KR-based emulsion electrospun fiber mats are potentially useful new nanofiber-based biomaterials in their use as drug carriers to treat diabetic wounds.Publication Open Access Marine-derived bioceramics for orthopedic, reconstructive and dental surgery applications(2022-11-01) OKTAR, FAİK NÜZHET; ÜNAL YILDIRIM, SEMRA; GÜNDÜZ, OĞUZHAN; EKREN, NAZMİ; ALTAN, ERAY; OKTAR F. N. , Unal S., GÜNDÜZ O., Ben Nissan B., Macha I. J. , Akyol S., Duta L., EKREN N., ALTAN E., YETMEZ M.Bioceramics are a fast-growing materials group, which are widely used in orthopedics, maxillofacial, dental, and reconstructive surgeries. They are produced using raw materials either from synthetic or natural sources. As naturally originated resources, the bones of sheep and cows are used after converting to calcium phosphates. Human-originated sources in the past were obtained from human cadaver bones, however now-a-days this has been discontinued. On the other hand, the \"golden standard\" in the reconstruction surgery has been using patients own bones, -i.e., autogenous bones, which heal better than other alternatives. Besides natural products, synthetic materials are produced from a range of inorganic raw and natural materials based on marine sources, such as corals, and other marine-derived materials (i.e., seashells, nacre). These are used to produce bioceramics and hence implants, devices, and bone grafts. Although during the last four decades a number of excellent books and book chapters have been published, no comprehensive review has been yet reported to cover the available marine materials and to indicate the related work and corresponding references to allow for both medical and ceramic scientists to access directly and open new avenues for further research on marine structures and their applications in orthopedic, maxillofacial, and reconstructive surgery areas. Hence, this review covers the general marine structures, their locations and availability in different countries and, current research on production methods of these unique structures that are difficult to fabricate synthetically. The authors are confident that this comprehensive review will be an excellent source not only for the ceramists, but also for the medical scientists.Publication Open Access A Hydrophobic antireflective and antidust coating with $\text{SiO}_2$ and $\text{TiO}_2$ nanoparticles using a new 3-D printing method for photovoltaic panels(2022-07-01) EKREN, NAZMİ; SAĞLAM, ŞAFAK; Ekren N., Sarkin A. S., Sağlam Ş.The main outdoor factors that reduce the efficiency of the photovoltaic (PV) panel are the reflection and refraction of light, dirt, dust, and organic waste accumulating on the panel surface. In this article, an antireflection, self-cleaning coating was applied on the PV panel cover glass with a new method. With the coating, the surface has been given a hydrophobic feature. As a coating method, a 3-D printer has not been seen in the literature and used as a new method. The electrospinning method has also been tried as an alternative method. Solutions in different combinations were developed using polylactic acid or polymethylmethacrylate polymer, chloroform ($\text{CHCl}_3$) as a solvent, and silicon dioxide ($\text{SiO}_2$) and titanium dioxide ($\text{TiO}_2$) nanoparticles as primary materials in a modified 3-D printer for bioprinting. Five PV panels were obtained by applying different 3-D parameters from three solutions, which have the best results. Coating thicknesses are in the range of 3.12-8.47 mu m. Coated and uncoated PV panels were tested in outdoor conditions for ten-day periods. The power outputs of the PV panels were measured, and their ten-day average efficiency was presented. According to the results, the highest efficiency increase is 8.7%. The highest light transmittance is 88.2% at 550 nm. In addition, hydrophobic properties were observed on all surfaces and the water contact angle was measured as 96.18 degrees.Publication Open Access Manufacturing of a portable electrospinning gun for biomedical applications(2022-01-01) EKREN, NAZMİ; EKREN N., Karacan C. E.Electrospun patches have attracted interest in different biomedical fields, including tissue engineering and drug delivery. Portable electrospinning guns promise faster and more practical interventions in these areas. In this article, the design, construction and testing of a portable electrospinning gun are described to produce fiber and particle products. Results were discussed depending on the electrospinning gun\"s working system and properties of the products. The electrospinning gun system could have a high voltage of up to 30 kV. Also, no heating problems were encountered during high voltage values. Due to the uniformity, reproducibility and tunability of the produced PCL and PMSQ fibers, it can be said that electrospinning gun can be used in nanotechnology, drug delivery systems and wound dressing applications.Publication Open Access Semi-conductor Applications to Printed Circuits on Flexible Surfaces(2022-06-01) EKREN, NAZMİ; Ekren N., Darkın A. S.The most common type of identification system today is RFID. RFID circuits are used as covered with plastic. With the increase in usage areas, it is also used on metal, wood, paper, and plastic product. In this study, the behavior of the same circuit on different surfaces was investigated. The surface impedance and signal reflection coefficients of RFID tag antennas were investigated based on paper, plastic, and textile surfaces. According to the results of the electrical and mechanical tests, the best results in terms of reflectance coefficients and surface impedances of RFID tags are on PET surfaces. The surface impedance and the reflection coefficients were high on paper surfaces. The lowest values were measured on textile surfaces. According to the results, it has been seen that RFID antenna application on plastic, paper, and textile surfaces is possible and usable. Index Terms— Flexible surface, Identification, Reflection coefficient, RFID, Surface impedancePublication Open Access Akıllı Mutfak İçin Tasarlanmış Sistemler Üzerine Bir Derleme(2020-03-01) EKREN, NAZMİ; Ekren N., Karagöz Z.Today, with the rapidly developing technology, many innovations have entered our lives. The first of these is the various systems that make our life easier. These systems can be adapted to any area of our lives. The purpose of these systems is to use energy effectively as well as making life easier. If the system is well designed and integrated with the internet of things, it serves user comfort in every respect. Studies designed for each individual and environment have started to be widely seen. In this study, the concept of smart home was started and contemporary smart kitchen designs that are produced based on various scenarios and supported by many additional systems are examined. Given the elements such as energy, time and comfort, it has always been more logical to choose a smart system. This is also seen in the studies examined. Keywords: smart kitchen, refrigerator, smart building, energy saving, internet of things, machine learning, artificial intelligence, time savingPublication Open Access DALI Compatible Smart LED Driver Controller with Wi-Fi Communication(2023-04-01) EKREN, NAZMİ; Ekren N., Söğüt B.DALI (Digital Addressable Lighting Interface) is one of the communication types commonly used in smart LED systems. It is a type of wired communication and is usually used in large facilities. The fact that it provides energy efficiency and supports user comfort increases the preferability of these systems. Energy savings can be achieved by making scenario definitions for LED drivers. An example is ensuring that the LED driver works at a certain time interval by setting the timing gap. Thanks to the dimming feature, it can be ensured that the light intensity remains at a certain level. With the help of sensors, the brightness level of the LED driver can be adjusted according to the light level outside. In this study, the design of the LED driver controller, which is controlled via Wi-Fi communication with the user interface supporting the DALI protocol, will be mentioned. Communication of the developed controller with the user interface will be carried out wirelessly. Wi-Fi has been preferred. The hardware part of this developed system consists of a processor-supported control circuit, a communication unit circuit and DALI hardware circuit parts. The designed smart LED driver controller is capable of fulfilling the standard requirements of the DALI protocol. It converts the command information received over Wi-Fi to the DALI protocol and provides control of the LED driver. The control device will be controlled and monitored via smartphone, computer, tablet, and web. In conclusion, with the commands given from the user interface, the LED driver turns on/off the light, increases / decreases the light intensity and similar commands available in DALI standards are controlled.Publication Open Access A review of line suspended inspection robots for power transmission lines(2023-01-01) EKREN, NAZMİ; EKREN N., Karagöz Z., Şahin M.Inspection and maintenance of power transmission lines are crucial in terms of providing uninterrupted power for the consumers. Inspection and maintenance of transmission lines passing through areas that are difficult to reach and pass through are usually carried out by workers or with the help of helicopter. These methods are not effective in terms of time, energy, safety, economy, and efficiency. Transmission line inspection robots can perform this task safely, efficiently, economically, quickly with the least risk. In this study, theoretical and experimental studies on line suspended power transmission line inspection robots in the literature are examined. Details of robots with different mechanisms are presented. Robots, which perform the line inspection process with the help of cameras and sensors, can also overcome various obstacles on the line. Produced robot prototypes have been tested in the field and laboratory environment. In this paper, these robots are grouped as those that move on live lines and ground wires. In addition, the advantages and disadvantages of robots have been determined depending on the line they move. Looking at the studies in the literature, it can be said that the inspection of power transmission lines with the help of robots is the most appropriate method compared to traditional methods.