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Daubechies dalgacıkları kullanılarak EEG sinyallerinden epileptik nöbetlerin belirlenmesi
A seizure is a sudden and abnormal activity of brain, caused by disorderly electrical discharge of cerebral neurons. One of the most known seizures is recurrent attacks namely epileptic seizures which result from uncontrolled discharges of nerve cells. A traditional electroencephalogram (EEG) is often helpful to detect this uncontrolled process that indicates epilepsy. The visual detection of the seizures is required noticeable effort and time, especially in the long recordings, therefore alternative methods are needed. In the literature, there have been various epilepsy detection studies using different approaches. However, most of them utilizes patient-specific classifiers. In this study, wavelet-based algorithm is adopted to different classification methods for detection of epileptic seizures. To detect the effective frequency intervals of epileptic seizure, it is important to reach subbands of signal. Thus, choosing the suitable mother wavelet that resembles epileptic seizure is challenging. Consequently, ideal order Daubechies (db) wavelet becomes a critical point to achieve best performances. Here, it is selected Daubechies wavelets from db2 to db10 which have strong correlation with seizures to decompose the original EEG signal. The algorithm is applied on two different datasets. Eventually, the most appropriate eight features are used for classification model. Various machine learning algorithms namely, Decision Trees, Discriminant Analysis, Naive Bayes, Support Vector Machine (SVM), and k-Nearest Neighbor are used to differentiate epileptic and non-epileptic groups. The results show that db10 gives the best ACC performance of 95.83-100% in beta band using SVM classifier. This method can be a good alternative to the traditional approaches.
Manyetik rezonans görüntüleme sistemleri için 23NA/1H çift bantlı, bilateral esnek meme bobini
A dedicated breast coil plays a significant role in the diagnosis of breast cancer because it can increase the signal to noise ratio (SNR) and therefore the image quality. Since breast coils used in the clinics have a fixed target volume and are not compatible with every patient, the resulting image may be insufficient for an accurate diagnosis. In this thesis, a dual band sodium/proton bilateral breast coil made of a wearable elastic conductive textile (WECOT), which can be compatible with the volume of interest, was described. The design of the breast coil consisted of the production of the conductive textile, the design of a single-channel sodium WECOT breast coil (BC), a two-channel lateral proton WECOT-BC, and a four-channel bilateral proton WECOT-BC. First, a high-conductive silver thread was woven with elastofiber in a weaving machine to produce WECOT with 115 percent elasticity. Phantom studies of the single-channel sodium WECOT-BC demonstrated that SNR was between 30-140 and the coil yielded correct estimations in sodium chloride solutions having different concentrations. A two-channel lateral proton WECOT-BC having a three-stage impedance matching circuit providing broad-band matching was tested in three different sized phantoms, namely, small, medium, and large. While, SNR of the two-channel WECOT-BC was between 60-120 in the small and medium phantom and 60-100 in the large phantom, the minimum resolution of 0.25 mm was obtained. SNR of the four-channel bilateral proton WECOT breast coil was between 100-200 in all three phantoms and the minimum resolution of 1 mm was achieved.
Tıbbi görüntüleme sistemlerine yönelik bilgisayar laboratuvarı deneylerinin tek bir nesne için tasarlanması, uygulanması ve değerlendirilmesi
Medical imaging systems (MIS), a crucial aspect of the electrical and electronics engineering (EEE) curriculum, encompasses a wide range of approaches, including physics, instrumentation, data gathering, image production, modeling, and quality evaluation. Although many EEE curricula include a well-structured MIS course that introduces students to all contemporary diagnostic imaging systems, MIS laboratory work is confined to image processing. In this thesis, a set of laboratory experiments has been designed in order to increase the applicability and understanding of studies related to MIS. The functioning of conventional X-ray, Computed Tomography (CT), and Magnetic Resonance Imaging (MRI) modalities are simulated by utilizing the Shepp-Logan phantom. Traditional biomedical image acquisition techniques have been analyzed using the same phantom to facilitate an understanding of their differences and similarities. Through simulations for each modality, a hands-on learning strategy for imaging systems is developed. In the developed experimental procedures, multiple states can be displayed for each imaging system by using adjustable parameters during the simulation of each modality through algorithms created for each specific case. All conceivable scenarios are aimed to be simulated. The acquired outcomes offer the possibility of comparing the different modalities as well as various conditions of the imaging systems. The content consists of projection and back-projection for X-ray radiography and CT, while k-space is described processed and several reconstruction methods are analyzed for MRI.
Transradiyal kol hareketleri için iki kanal EMG sınıflandırması
In this thesis, the classification algorithm for electromyography (EMG) based prosthesis which can be developed for individuals who have undergone transradial arm amputation has been studied using artificial neural networks (ANN). Surface electromyography (sEMG) has been preferred for ease of application in order to receive EMG signals. The data were processed and various features were extracted. Mean absolute value (MAV), root mean square (RMS), simple square integral (SSI), variance of EMG (VAR), log detector (LOG), maximum fractal length (MFL), wavelength (WL), average amplitude change (AAC), difference absolute standard deviation value (DASDV), Willison amplitude (WAMP) and slope sign change (SSC) features are given as an input matrix to the ANN to be trained for classification purposes. In this study, four different movements as relaxed hand, hand close, wrist flexion, and forearm supination are classified. The accuracy, sensitivity, specificity, and precision performance metrics were calculated as a result of ANN training and examined and interpreted. As a result of the study carried out within the scope of this thesis, the effects of the number of hidden layer neurons, feature extraction, feature selection and individualization of ANN to classification performance were evaluated. A classifier that provides high classification performance metrics were established by training with feature sets formed by grouping and combining features with individual low accuracy rates. The two feature sets created achieved 88 percent accuracy with generalization and 95 percent accuracy with individualization.
Denge ve lokomotor sistem fonksiyon testleri için denge platformu gömülü tasarımı
In this study, a balance platforms prototype with three motor two degrees of freedom was designed for advanced physiotherapy scenarios by taking of the consideration with general features of parallel mechanisms, kinematics and study spaces is constructed. This prototype structure, considering the problems that limited usage areas such as existing balance assessment and training platform systems need fixed and large areas lack of portable features, is designed to be portable, small in size and movable in two degrees of freedom. By Portable active balance platform prototype controlled by an embedded computer, it will also be possible to conduct tests and exercises routinely in clinics with a remote and traceable manner. As a result of these studies, two pre-prototype and a real scale prototype which testable movement of humanoid robot which is average human weight has produced. During the ongoing process within this project; development of software and improved interface which one processing of data that comes from prototype and user friendly interface software has completed. A patent application has been made for the entire platform with the combination of mechanic, electronic and cloud data software systems by the Scientific Research Project Group from Dokuz Eylül University.
PAF (paroksismal atriyal fibrilasyon) hastalarının teşhisi için TBA (temel bileşenler analizi) boyut azaltma metoduyla elde edilen özniteliklerin performans analizi
Principal Component Analysis (PCA) is an offered scheme for feature extraction and dimension reduction. It has been used extensively in many applications involving high-dimensional data. In this study, we compared the effectivity of PCA features extracted from 33 short-term Heart Rate Variability (HRV) features obtained from normal sinus rhythm (NSR) ECG records for the diagnosis of Paroxysmal Atrial Fibrillation (PAF) disease. Within this framework, different data sets consisting of 33 to 1 features obtained from PCA were used as input to the classification algorithm, which is chosen as the K-Nearest Neighbor (kNN) algorithm. Different values for K and difference distance metrics were utilized to find the best performance. Then the same procedure is applied to another HRV dataset. This set consists of 8 best HRV indices chosen from among the 33 HRV indices by a Genetic Algorithm. The obtained results from both studies elicit that it is possible to further reduce the number of input dimension of a classification system by using PCA algorithm without a reduction in the performance of the system.
Erıca arborea L. bitkisinin asetilkolinesteraz aktivitesinin ve antioksidan kapasitesinin belirlenmesi
Erica arborea L., also known as "wild heather", is an evergreen shrub that grows between one and seven meters tall. It has dark green, needle-shaped leaves and numerous white, bell-shaped flowers. It exhibits antioxidant activity, as it can produce certain phytochemicals, such as flavonoids and phenolic molecules. It has been used in traditional medicine to promote urination and reduce inflammation. In this context, the current study investigates the plant's acetylcholinesterase inhibitory activity and antioxidant capacity. For this reason, the ethanolic extract was prepared from the dried aerial parts of the plant, and FRAP, DPPH, total flavonoid content, and total phenolic content were determined to identify these activities of the plant. 50, 100, 150, and 200 μg/mL concentrations were tested for the activity assays. The IC50 value for DPPH free radical scavenging activity was determined to be 82.09719 μg/mL. At 0.1 mg/mL, the extract showed a gallic acid equivalent phenolic content of 5.72 μg/mL. Acetylcholinesterase inhibitory action was determined employing the Ellman method, with IC50 calculated as 0.5285±0.025 mg/mL. The cytotoxic and antitumor effects of Erica arborea extract were also evaluated on multiple models (L929, HUVEC, and U87M cells) using the MTT assay. The extract successfully reduced the viability of U87MG cells through selective cytotoxicity, while proliferative responses were observed in both L929 and HUVEC cells. Due to its selective properties, which show low toxicity to non-neuronal cell types, Erica arborea can be a suitable option for targeted cytotoxicity, an admirable source for the production of antioxidant agents, natural source for the treatment of neurodegenerative diseases such as Alzheimer's disease. Keywords: Erica arborea, Acetylcholinesterase, Antioxidant activity, Alzheimer's disease, Cytotoxicity, DPPH, FRAP, Neurodegenerative diseases.
Montmorilonit kili içinde yağların kapsüllenmesi: Potansiyel yara iyileşmesi için antibakteriyel ve antioksidan aktivitelerin araştırılması
Vegetable oils and essential oils have advantageous uses in different fields of science and technology, such as antibacterial activities, antioxidant and anti-inflammatory properties. Encapsulation of these oils often require different formulations such as emulsifiers and/or different types of synthetic additives. On the other hand, there is still room for development of natural based formulations for oil encapsulation. In this study, montmorillonite clay is used for a one-pot encapsulation of different types of oils, which are tea tree oil, tamanu oil and safflower oil. Clay-oil mixtures were characterized using Fourier transform infrared spectroscopy (FTIR), ferric reducing antioxidant assay (FRAP) and antibacterial tests. Results show that these formulations are effective against Gram-positive and Gram-negative bacteria and have potential uses in different applications.
Seryum katkılı biyopolimer filmlerin antimikrobiyal özelliklerine kuazi- kriyojelasyon etkisi
This study examines how cryogelation affects sodium alginate films crosslinked with cerium nitrate by comparing two types: AlgCe³⁺ and cryogelated QuasiAlgCe³⁺. The films were prepared by dissolving sodium alginate in water, then crosslinking with cerium nitrate for 12 hours at room temperature, and QuasiAlgCe³⁺, adding a freeze-thaw step at - 21°C for 24 hours. FTIR spectroscopy, swelling behavior in different solutions, water vapor transmission rate (WVTR), and UV-Vis absorbance characteristics were used to examine the physical and chemical structure of the films. Swelling tests revealed QuasiAlgCe³⁺ absorbed more water—reaching 115% in isotonic sodium chloride solution and 98% in deionized water—compared to AlgCe³⁺, and its WVTR was higher at 2614.15 g/day·m² versus AlgCe³⁺'s 1392.94 g/day·m², suggesting a more porous structure. However, when placed in PBS solution, they began to degrade and completely broke down in less than 15 minutes. UV-Vis results show AlgCe³⁺ is clearer above 300 nm, making it better for transparent uses like bandages, while QuasiAlgCe³⁺ blocks more UV light, which is better for protective coating applications. Overall, QuasiAlgCe³⁺ is more suited for moisture-regulating and UV-protective applications, like wound dressing.
Kanser kök hücrelerinin mikro doku oluşumuna ve organizasyonuna etkisi
Bu tez çalışmasında kanser kök hücrelerinin mikro doku oluşturma yetisi, mikro dokuda oluşturdukları yerleşim örüntüsü ve mikro doku kültür yönteminde karakterizasyon yöntemlerinin incelenmesi amaçlanmıştır. Bu kapsamda CD133+ hücreleri SaOs-2 hücre dizisinden manyetik aktif hücre ayırım sistemi (MACS) tekniği ile ayrımlanmıştır. Hücreler mikro doku oluşturma yetilerinin araştırılması amacıyla 3D Petri Dish® tekniği kullanılarak oluşturulan agar jellerde farklı sayılarda kültüre edilmiş ve mikro doku oluşturma yetileri ters faz ışık mikroskobu ile izlenmiştir. Daha sonra CD133+ hücre oranı sırasıyla %50, %25, %12,5, %10, %5 ve %2,5 olacak şekilde kırmızı ve yeşil floresan boya ile boyanan CD133+ ve CD133- hücreleri agar jellerde beraber kültüre edilmiştir. Son olarak CD133+, CD133- ve SaOs-2 hücreleri kullanılarak oluşturulan mikro dokuların karakerizasyonları yapılmıştır. Bu amaç doğrultusunda immünohistokimyasal analiz yöntemi ile CD133, Sox2, OCT3/4 ve Ki67 ifadesine, gerçek zamanlı RT-PZR ile CD133, Sox2, OCT3/4, nanog ve nestin gen ifadesine bakılmıştır. Ayrıca mikro dokulardaki canlı ve ölü hücrelerin varlığı canlı&ölü hücre analizi ile belirlenmiştir. Yapılan analiz sonucunda CD133+, CD133- ve SaOs-2 hücrelerinin yüksek hücre canlılığıyla mikro doku oluşturdukları ve CD133+ hücrelerinin üç boyutlu (3B) mikro dokularda rastgele bir yerleşim gösterdiği anlaşılmıştır. Yapılan karakterizasyon çalışması ile kontrol grubu olarak belirlenen iki boyutlu (2B) kültür sistemine göre köklükle ilişkilendirilen gen ifadelerinde belirgin bir fark olduğu anlaşılmıştır. Elde edilen bu veriler mikro dokuların 3B tümör modeli olarak kullanılabileceğini ve kanser çalışmalarında 2B ile hayvan çalışmaları arasında köprü görevi görebileceğini göstermiştir.
Bakteriyel selülozdan doğal yüz maskesi üretimi
Bakteriyel selüloz (BS) eşsiz özellikleri sayesinde kozmetik, medikal, biyomedikal, elektronik, gıda ve kağıt sektörlerinde kullanılabilen doğal bir polimerdir. Bu tez kapsamında, Gluconacetobacter xylinus suşu kullanılarak yeni geliştirilen besiyerinde BS üretimi istatistiksel olarak optimize edilmiş ve örnekler karakterize edilerek antioksidan madde yüklemesi sonrası yüz maskesi olarak kullanılabilirliği araştırılmıştır. Sekiz parametre (karbon miktarı, protein miktarı, başlangıç pH, yüzey alanı/hacim, inokulum miktarı, inkübasyon süresi, sitrik asit, sıcaklık) Plackett-Burman Tasarımı ile elenmiş ve anlamlı üç parametre [inkübasyon süresi (%63,50), protein miktarı (%12,23), inokulum miktarı (%9,57)] Merkezi Bileşen Tasarımı ile optimize edilmiştir. Statik kültürde BS üretimi için optimum koşullar: 2,5 g/L karbon, 2,75 g/L protein, % 9,3 v/v inokulum oranı, 1,15 g/L sitrik asit, 2,7 g/L Na2HPO4, 30°C inkübasyon sıcaklığı, pH 5,5 ve 9 gün inkübasyon süresi olarak tespit edilmiştir. Elde edilen model, doğrulama deneyleri sonrasında CHb (Carob-Haricot bean) besiyeri ile BS üretiminin tahminlenmesi ve optimize edilmesi için kullanılmıştır. Bu tez, yeni geliştirilen CHb besiyerinin yüksek tamponlama kapasitesinde olduğunu ortaya koymuştur. Üretilen BS yüz maskesi örneklerinin karakterizasyonu X-Ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) ve Texture Profile Analysis (TPA) ile gerçekleştirilmiştir. Taurin salım hızı ve stabilitesi (4 ay) Liquid chromatography–Mass spectrometry (LC/MS) ile, koruyucu etkinliği ise challenge ve mikrobiyal stabilite testleri ile analiz edilmiştir. Bu tez kapsamında üretilen BS tabanlı yüz maskesi, yüksek su içeriği (>%99) ile nemlendirme ve 30 ±3,5 taurin/5 dakika salımı ile de antioksidan özellik göstermektedir.
Lizozim adsorpsiyonu için yeni nesil kriyojellerin sentezi
Bu çalışma, organik dialdehit monomer sentezi ve bunların kopolimer olarak kullanıldığı kriyojel formundaki polimerlerin sentezi olmak üzere iki kısımdan oluşmaktadır. Tezin ilk kısmında, monemerlerin sentezi ve bu monomerlerin spektroskopik yöntemlerle yapıları aydınlatıldı. Tezin ikinci kısmında, bu monomerler kullanılarak sentezlenen kopolimerik kriyojellerin yapı ve karakterizasyon analizleri yapıldı. Ayrıca, karakterize edilen kriyojeller lizozim saflaştırılmasında kullanılarak biyoteknolojik uygulaması yapıldı. Adsorpsiyon deneyleri, farklı ortam koşullarında (pH, başlangıç derişimleri, sıcaklık, iyon şiddeti) kesikli deney sisteminde incelendi. Son olarak adsorpsiyon-desorpsiyon döngüsü 5 kez tekrarlandı ve adsorpsiyon kapasitesinde önemli bir değişim gözlenmeden lizozim saflaştırılmasında kullanılabilir olduğu gözlendi.