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Investigation of the electromagnetic shielding efficiency of FeB and Fe2B: ab-initio calculations
(Institute of Physics, 2024) Üşenti, Hakan; Duru, İzzet Paruğ
The electromagnetic (EM) pollution that we are exposed to in our daily lives has reached levels that threaten the health of living organisms and the stable operation of sensitive systems. The most effective way to protect against this pollution is to create isolated areas framed with shielding materials that can minimize the transmission of EM radiation. The development of shielding materials with high physical endurance against external factors to meet the needs of various sectors remains a popular research topic. This process, which started with metal plates, has continued with the development of doped polymers and composite materials. In recent years, materials with 2D structures have been developed. In this study, the shielding effectiveness (SE) of FeB and Fe2B nanostructures are revealed using ab initio calculations in Perdew-Burke-ErnzerhofSol scheme. SE has been widely figuring out via optical properties which are strongly related to mechanical and electronic properties herewith magnetic phases. The ferrimagnetic FeB and Fe2B nanostructures are considered. Besides, we focus on the thickness and photon energy dependent behavior along various projections. The findings demonstrate shielding performance at levels of >20 dB. Although both materials show similar shielding performance, it is observed that Fe2B is promising when compared to FeB. This study demonstrates that FeB and Fe2B, members of the MBene family, are promising materials not only because of their superior physical and chemical properties but also because of their shielding performance.
DDoS detection in electric vehicle charging stations: A deep learning perspective via CICEV2023 dataset
(Elsevier B.V., 2024) Anlı, Yağız Alp; Çıplak, Zeki; Sakalıuzun, Murat; İzgü, Şeniz Zekiye; Yıldız, Kazım
Distributed Denial of Service (DDoS) attacks have always been an important research topic in the field of information security. Regarding specialized infrastructures such as electric vehicle charging stations, detecting and preventing such attacks becomes even more critical. In the existing literature, most studies on DDoS attack detection focus on traditional methods that analyze network metrics such as network traffic, packet rates, and number of connections. These approaches attempt to detect attacks by identifying anomalies and irregularities in the network, but can have high error rates and fail to identify advanced attacks. Conversely though, detection methods based on system metrics use deeper and more insightful parameters such as processor utilization, memory usage, disk I/O operations, and system behavior. Such metrics provide a more detailed perspective than network-based approaches, allowing for more accurate detection of attacks. However, work in this area is not yet widespread enough further research and improvement are needed. The adoption of advanced system metrics-based methods can significantly improve the effectiveness of DDoS defense strategies, especially in next-generation and specialized infrastructures. This paper evaluates the applicability and effectiveness of Long ShortTerm Memory (LSTM) and Feed-Forward Network (FFN) in detecting DDoS attacks against electric vehicle charging stations through system metrics using CICEV2023 dataset. Experimental results show that the LSTM based model offers advantages in terms of speed and processing capacity, while the FFN is superior in terms of the accuracy.
Investigation of obsessive compulsive disorder with FFT dipol approximation by means of EEG
(IEEE, 2015) Özçoban, Mehmet Akif; Aydın, Serap; Kara, Sadık; Tan, Oğuz
EEG analysis has been used in pathophysiological research of Obsessive Compulsive Disorder (OCD) that is one of the neuropsychiatric disease. EEG abnormalities was observed in brain cortex of patients with OCD. Fast Fourier Transform (FFT) Dipol Approximation Method (FFTDA), used for source localization and superior to conventional FFT method, has also been used for measurement of the level of EEG synchronization. In this research, phase differences between cortical neural oscillations was computed by using FFTDA. Then, analysis of 19 channel EEG series, collected with international 10-20 electrode placement system, shows the loss of Theta band phase synchronization in patients with OCD.
Invetigations of mechanical properties after dissimilar steels post-weld of Q345B steel
(Pamukkale University, 2020) Çiçek, Bünyamin; Aydoğmuş, Tuna; Gündoğdu İş, Emine; Sun, Yavuz
In this study, it has been reported that Q345B steel combine with different steels using electric arc welding method and the mechanical properties were investigated. Produced by hot rolling processes, Q345B steel is a low-alloyed medium tensile strength and highly usable steel. The steel used contain less than 0.2% carbon and less than 0.55% silicon, chromium and nickel. In this study, Q345B steel generally used at low-pressure/temperature zones in thermal power plant (boiler wall etc.) is combined with 16Mo3 and P265GH steels. The Q345B steel is welded to make the mechanical properties easy to compare. After joining, specimens were collected from the welded areas and used in the preparation of mechanical and metallographic processes. In this process, all joints were subject to tensile, charpy, hardness and bending tests. In addition, the collection of macro images from welding were used in observation of transition zones which were operated. Electrodes with a basic character cover were used (E7018) as filler metal in the joining processes. All mechanical tests met the requirements of the relevant standards and all welds were identified as valid weld.
An alternative supplemental feeding method for preterm infants: the supplemental feeding tube device
(Tubitak Scientific & Technological Research Council Turkey, 2021) Çalıkuşu İncekar, Müjde; Çağlar, Seda; Kaya Narter, Fatma; Tercan Tarakçı, Emriye; Özpınar, Emine; Demirci Ecevit, Esra
Background/aim: The purpose of this study was to determine the effects of the supplemental feeding tube device (SFTD) and bottle methods on weight gain, transition to full breastfeeding, breastfeeding success, and duration of discharge in preterm infants. Materials and methods: This randomized controlled trial was conducted with a total of 46 preterm infants including 23 infants in study (SFTD) and control (bottle) groups. An information form, an infant follow-up form for feeding, and LATCH breastfeeding assessment instrument were used to collect the data. Results: The gestation week of the infants in the study group was 31.22 +/- 2.76, and in the control group it was 30.52 +/- 2.47. The birth weight of the infants in the study group was 1586.3 +/- 525.35 g and 1506.09 +/- 454.77 g in the control group. The daily weight gain of the infants was 24.09 +/- 15.21 g in the study group and 27.17 +/- 17.63 g in the control group. The infants in the study group (4.70 +/- 2.44 days) transitioned to full breastfeeding earlier than those in the control group (6.00 +/- 4.10 days). LATCH 2nd measurement scores were significantly higher in both groups than LATCH 1st measurement scores (p < 0.01). Although it was not statistically significant (p > 0.05), the infants in the study group (10.22 +/- 5.20 days) were discharged earlier than those in the control group (13.48 +/- 8.78 days). Conclusion: The SFTD and bottle methods were determined to be similar in terms of daily weight gain, transition to full breastfeeding, breastfeeding success, and duration of hospitalization.
H-indeksi ve akademik başarıyı ölçme sorunu: eksiklikler ve sınırlılıkları aşma çabası
(Mehmet Akif Ersoy Üniversitesi, 2023) Fırat, Serhat; Oğuz Alramazanoğlu, Buket; Genç, Gülşen; Karaşin, Yusuf; Kurutkan, Mehmet Nurullah
Bu çalışmanın amacı, h-indeksinin eksikliklerini belirleyip, bu yönde çözüm üretip h-indeksinin sınırlarını ortaya koymaktır. Bu çalışmada ikincil veri analizleri içerisinde yer alan doküman analizi kullanılmıştır. H-indeksi dışında bilimsel dünyada kullanılan indeksler genel hatlarıyla 3 grupta incelenmektedir. Bu doğrultuda 3 bilim insanı her bir indeks türü karşılaştırılacak şekilde toplamda 33 indeks incelenmiştir. Bilim insanlarının yayınları ve atıf sayılarında Google Scholar üzerinden Ekim 2021 dönemi baz alınmıştır. Hirsch tarafından geliştirilen, bir bilim insanının n sayıda yayınına gelen n sayıda atıfın çıktı olarak sunulduğu h-indeksi bilimsel dünyada en çok kullanılan ölçüt olmasına rağmen eksik kalan yönleri bulunduğu tespit edilmiştir. Çalışmada h- indeksi düşük olan bilim insanı diğer indeks türlerinde daha yüksek değere sahip olabileceği görülmüştür. Çalışmada incelenen diğer indekslerin h-indeksine alternatif olan indeksler olduğu ve tüm sınırlılıkları aşan yeni bir indeks türü geliştirilmesi gerektiği sonucuna ulaşılmıştır.
Dimensional accuracy analysis of samples printed in delta and cartesian kinematic three dimensional printers
(Gazi University, 2021) İncekar, Erkan; Kaygısız, Hüseyin; Babur, Sebahattin
The motion mechanisms of manufacturing and robotic systems are developed in different structures, mainly in cartesian and delta structures having series or parallel movement abilities according to the capacity and construction structure of the system. Different systems are used according to the criteria such as bearing load capacity, sensitivity or cost of the system. In this study, the performances of machines installed in the delta and cartesian kinematic structures, which are mostly used in the kinematic systems of three - dimensional printers, were analyzed. In this context, in two different machines with these two construction structures, the same boundary conditions and 4 pieces of calibration parts especially in manufacturing features were printed. 23 different elements that constituted the calibration part were measured, tabulated, statistically analyzed, and the acceptable measuremental tolerance ranges of the elements were determined and the accuracy values of the machines were compared. As a result of this study, according to T test results, 15 of the 23 measurements on the Cartesian system based three-dimensional printers were obtained as acceptable in terms of tolerance range as well as 9 of the 23 different measurements were obtained as acceptable on Delta system. Consequently, operation accuracy of the Cartesian system based three-dimensional printers were higher than the Delta system under the same working conditions and manufacturing parameters.
Synthesis of new regioisomers of 5-Nitro-1,4-Naphthoquinone, evaluation of antioxidant and catalase inhibition activities
(Slovensko Kemijsko Drustvo, 2022) Abdassalam, Aesha Fsh; Deniz, Nahide Gülşah; Sayil, Çiğdem; Özyürek, Mustafa; Yeşil, Emin Ahmet; Salihoğlu, Hüseyin
The studies on nitronaphthoquinone derivatives are rare in the literature, and the nitro group associated with the aromatic ring in the quinone system is known to increase the biological activity of naphthoquinone due to its electron-withdrawing properties. In the course of quinone derivatives, the new N(H)-substituted-5-nitro-1,4-naphthoquinones (NQ) as regioisomers were synthesized by reactions of 2,3-dichloro-5-nitro-1,4-naphthoquinone with some heterocyclic ring substituted nucleophiles such as anilines, piperazines, or morpholines, according to a Michael 1,4-addition mechanism. Five NQ regioisomer couples having different functional group (2-chloro-isomers 3, 5, 7, 9 and 13; 3-chloro-isomers 2, 4, 6, 8 and 12) are reported here. All new synthesized compounds were characterized by spectroscopic methods and two-dimensional NMR techniques H-1-H-1 correlated spectroscopy (COSY). The synthesized NQ regioisomers were evaluated for catalase enzyme inhibitory activities and antioxidant efficiency. The synthesized regioisomers were screened for their antioxidant capacity using the cupric-reducing antioxidant capacity (CUPRAC) method. 2-Chloro-3-((2,4-dimethoxyphenyl)amino)-5-nitronaphthalene-1,4-dione (5) showed the highest antioxidant capacity with a 1.80 +/- 0.06 CUPRAC-trolox equivalent antioxidant capacity (TEAC) coefficient. Compound 5 also showed strongest catalase enzyme inhibitory activity. The antioxidant capacity results of all 2-chloro regioisomers are higher than the 3-chloro regioisomers. Likewise, also catalase enzyme inhibitory activities results were determined in the same way, except for one regioisomer pair. The catalase was effectively inhibited by the newly synthesized compounds, with % inhibition values in the range of 0.71-0.86%. Some of these NQ compounds also showed remarkable antioxidant capacities.
Mass mortality in endangered fan mussels Pinna nobilis (Linnaeus 1758) caused by co-infection of Haplosporidium pinnae and multiple Vibrio infection in Çanakkale Strait, Turkey
(Taylor & Francis Ltd, 2021) Künili, İbrahim Ender; Ertürk Gürkan, Selin; Aksu, Ata; Turgay, Emre; Çakır, Fikret; Gürkan, Mert; Altınağaç, Uğur
Purpose Pinna nobilis (fan mussel) is one of the most important endemic bivalve molluscs in the Mediterranean and mass mortality events were observed in these mussels in recent years. In this study, we report mass mortalities caused by Haplosporidium pinnae, which has been spreading in the Mediterranean for 3 years, and reached the canakkale Strait, which is the entrance of the Marmara and the Black Sea. Material and methods Field observations during sampling and subsequent histopathological, biochemical, genetic, and microbiological analyses were carried out. Results These analyses showed that H. pinnae infection spread among the natural beds of P. nobilis, causing severe tissue damage and oxidative stress. Our phylogenetic analyses suggested that the parasite spread through the Mediterranean much faster than thought. The results showed that vibriosis originating from Vibrio coralliilyticus, Vibrio tubiashii, Vibrio mediterranei, and Vibrio hispanicus, acted together with H. pinnae in infected individuals and caused death. Conclusion It is highly probable that the spread of H. pinnae to the Sea of Marmara and the Black Sea may occur earlier than expected, and it was concluded that mass deaths were caused by co-infection with H. pinnae and a geographically specific marine pathogen that can infect P. nobilis populations.
Scattering from an object behind multi-layer periodic gratings of cylindrical shapes
(Taylor & Francis Ltd, 2017) Kızılay, Ahmet; Saynak, Uğur; Uygur, Gökhan
The problem of electromagnetic scattering from a perfect electric conductor (PEC) object of arbitrary cross-section behind multilayer of periodic gratings of circular cylinders is solved by a hybrid method combining the Method of Moments (MoM), decomposition, and the Physical Optics methods. The periodic grating's periodic cell consists of multiple layers of lossy-dielectric scattering elements situated in free space. The PEC object under the periodic gratings assumed to be electrically large. A set of electric-field integral equations (EFIEs) for the perturbation currents both on the portion of the PEC object and the periodic gratings most strongly interacting with each other obtained using the surface equivalence principle and a decomposition method. Then, MoM is used to solve the EFIEs in the frequency domain to obtain the scattered electric field.
Proposing novel MAO-B hit inhibitors using multidimensional molecular modeling approaches and application of binary QSAR models for prediction of their therapeutic activity, pharmacokinetic and toxicity properties
(American Chemical Society, 2018) İş, Yusuf Serhat; Aksoydan, Busecan; Durdağı, Serdar; Yurtsever, Mine
Monoamine oxidase (MAO) enzymes MAO-A and MAO-B play a critical role in the metabolism of monoamine neurotransmitters. Hence, MAO inhibitors are very important for the treatment of several neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS). In this study, 256 750 molecules from Otava Green Chemical Collection were virtually screened for their binding activities as MAO-B inhibitors. Two hit molecules were identified after applying different filters such as high docking scores and selectivity to MAO-B, desired pharmacokinetic profile predictions with binary quantitative structure activity relationship (QSAR) models. Therapeutic activity prediction as well as pharmacokinetic and toxicity profiles were investigated using MetaCore/MetaDrug platform which is based on a manually curated database of molecular interactions, molecular pathways, gene disease associations, chemical metabolism, and toxicity information. Particular therapeutic activity and toxic effect predictions are based on the ChemTree ability to correlate structural descriptors to that property using recursive partitioning algorithm. Molecular dynamics (MD) simulations were also performed to make more detailed assessments beyond docking studies. All these calculations were made not only to determine if studied molecules possess the potential to be a MAO-B inhibitor but also to find out whether they carry MAO-B selectivity versus MAO-A. The evaluation of docking results and pharmacokinetic profile predictions together with the MD simulations enabled us to identify one hit molecule (ligand 1, Otava ID: 3463218) which displayed higher selectivity toward MAO-B than a positive control selegiline which is a commercially used drug for PD therapeutic purposes.
Individual and organizational effects of the corporate practices with the mediating role of lean intrapreneurship: differences between public and private sector in Turkey
(Elsevier Science Bv, 2015) Uslu, Tuna; Eryiğit, Nimet; Çubuk, Duygu
In our century the most important institutional infrastructural tools (IIT) of the companies are knowledge management (KM), occupational health and safety (OHS), quality management (QM) and standardization. Beforehands OHS practices were just aiming to recover the results of the risks after they had occured; but nowadays a proactive approach is applied, in which precautions are taken and also the psychological and social mood of the employees, ergonomics, work load, workplace conditions and managerial applications are taken into consideration. The relationship between all these IIT and a new concept which is lean start-up, that means to deliver the most simple and pure product or service to the customer is not known yet. Besides; in between IIT, of which are influential on the intrapreneurship of the employees are needed to be understood. In this study we discuss the effects of these IIT on the employee performance and organizational effectiveness with the mediating role of lean intrapreneurship.
Experimental study and numerical simulation for the development of critical performance parameters of eco-friendly Cu2ZnSnS4-based solar cells
(Elsevier Science Ltd, 2023) Belarbi, Faiza; Canci Matur, Utku; Tamin, C.; Rahal, Wassila Leila; Benghabrit, S.; Baydoğan, Nilgün; Adnane, Mohamed
This work aims to study the basic Characteristics of CZTS thin films produced by chemical solution process in addition to a numerical study of the CZTS-based solar cells. In this context, eco-friendly and cost effective thin films of CZTS were coated on glass substrates by sol-gel dip-coating method. This method is used to grow crystalline CZTS thin films without sulfidation processes. The structural and optical properties have been carried out by X-ray Diffraction (XRD) and UV/Visible spectroscopy. The oxidation states of CZTS thin film have been studied by, X-ray photoelectron spectroscopy XPS analysis. The performance of CZTS solar cells has been investigated with the simulator SCAPS-1 D. The impact of different parameters like the CZTS absorber layer thickness, the carrier doping density and the operation temperature has been studied to get better understanding of the properties of our cells.
A bio-based and non-toxic polyurethane film derived from Luffa cylindrica cellulose and L-Lysine diisocyanate ethyl ester
(Pergamon-Elsevier Science Ltd, 2021) Akay, Özge; Altınkök, Çağatay; Açık, Gökhan; Yüce, Hüseyin; Konuk Ege, Gözde
This study aims to explore the step-growth polymerization (SGP) between the most abundant biomass-cellulose (LCC) extracted from Luffa cylindrica (LC) and L-Lysine diisocyanate ethyl ester (L-LDI) to be achieved an unprecedented polyurethane network (PUR). The resulting bio-based and non-toxic PUR film is obtained by direct solution casting after SGP. The efficiency of the SGP is examined in detail Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (H-1 NMR) spectroscopies, water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry analyses (TGA and DSC) by comparing precursors and final film. Moreover, the biodegradation behavior of PUR achieved is evaluated in vitro both hydrolytic and enzymatic media. Based on the conducted analyses, PUR film shows higher hydrophobicity and degradation temperatures compared to raw LC and LCC. Moreover, it is determined that the PUR film more degradable than its precursors in both hydrolytic and enzymatic media. Consequently, the approach developed here is broadly adaptable to other functional isocyanate monomers and will be useful to scientists working on bioplastic applications.
Changes in gamma attenuation behaviour of sol-gel derived CIGS thin film irradiated using Co-60 radioisotope
(Elsevier Science Sa, 2017) Canci Matur, Utku; Baydoğan, Nilgün
Copper indium gallium (di) selenide-Cu(In, Ga)Se-2 (CIGS) thin films were fabricated on soda-lime silicate glass substrates using a layer-by-layer sol-gel dip-coating method. The irradiation procedure was handled using a certified Co-60 radioisotope at two different absorbed dose levels (at 0,03 and 0,05 Gray (Gy)) to examine the enhancements of optical and electrical properties of the CIGS thin films. Cs-137 (with 0,662 MeV) and Co-60 (with similar to 1,25 MeV) radioisotopes were used to evaluate the effect of the absorbed dose on CIGS thin films with different thicknesses by the gamma transmission technique. The irradiated CIGS thin films exhibited an improved optical band gap and electrical resistivity at the optimal layer thickness. This improvement occurs due to the enhancement of crystalline properties in comparison with those of non-irradiated CIGS thin films. The CIGS thin film of similar to 300 nm (11 layers) thickness was suitable for comparing changes in the linear attenuation coefficient after the irradiation process at two different absorbed dose levels. In the experiments, the gamma transmission technique was utilized to investigate the gamma attenuation properties of non-irradiated and irradiated CIGS thin films at different thicknesses against Cs-137 (with 0,662 MeV) and Co-60 (with similar to 1,25 MeV) gamma radioisotope sources. The irradiation process and the increase of thickness of CIGS thin films caused a higher linear attenuation coefficient, higher absorption and improvement in electrical conductivity. These results demonstrate the suitability of these materials for solar cell applications in aerospace technology, especially for high-altitude flight operations.

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