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Öğe Al2O3 PARTICLE SIZE EFFECT ON REINFORCED CU COMPOSITES PRODUCED BY HIGH ENERGY MILLING(2023) Öksüz, Kerim EmreProduction of copper (Cu) composites with a reinforced Cu matrix using mechanical alloying with Aluminum oxide (Al2O3) particles of different sizes was achieved using high-energy ball milling procedure. The initial materials consisted of inert gas-atomized spherical electrolytic Cu powders containing 0.5 wt. % commercial Al2O3 powders, with particle sizes ranging from 10 µm to 1 µm. Cu powders with different particle sizes of Al2O3 were high-energy ball milled at 500 rpm for 3 hours to attain a consistent distribution of Al2O3 throughout in the Cu matrix. The powders that were high-energy ball milled were then subjected to cold-pressing at 500 MPa and isothermally sintered for 1.5 hours at 880°C in an Ar atmosphere. The fabricated copper composite materials were characterized using X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDXS), density and macrohardness tests. The wear properties and mechanism were investigated through tribological pin-on-disc experiments, which revealed that the reinforcing effect was more significant when finely dispersed Al2O3 particles were combined into the Cu matrix compared to coarse Al2O3 particles.Öğe Boron-substituted biomaterials(Nova Science Publishers, Inc., 2023) Abuhamed, Nader; Arslan, Saynur; Öksüz, Kerim EmreBiomaterial scientists are interested in boron as a dopant element because of its natural functions in human hard tissues. However, boron does not exist in its elemental form in nature. Instead, it reacts with oxygen to form boric acid (H3BO3). Boron occurs naturally as borates, including orthoborate BO33-, metaborate BO2-, or tetraborate BO4O72- or as any salt containing these anions, such as sodium metaborate, Na+[BO2]-, and borax (Na+)2[B4O7]2-. Boron exerts a range of biological effects, including impacts on reproduction and embryogenesis, promoting wound healing and enhancing responses to injury or infection, influencing calcium and bone metabolism, and benefiting central nervous function. It also affects the presence or function of various hormones, such as thyroid hormone, insulin, estrogen, and progesterone, as well as calcium, magnesium, and vitamin D, which are involved in hard tissue metabolism. Research conducted at the molecular level has demonstrated that boron can increase RNA transcription within placental nuclei and activate mRNA translation, particularly for growth factors involved in wound repair and the formation of new blood vessels (angiogenesis). This chapter will provide a summary of the recent advances in the development of boron biomaterials that respond to specific biomedical applications. © 2024 by Nova Science Publishers, Inc. All rights reserved.Öğe Characterization of C/C Composites Produced Using 3D-preforms by CVD/CVI Method for Biomedical Applications(Sakarya University, 2025) Çamyurdu, Cemalettin; Ateş, Şahin; Öksüz, Kerim Emre; Demirkıran, Ayşe ŞükranIn this study, carbon/carbon (C/C) composite structures were produced by depositing a pyrolytic carbon matrix around carbon fibers found in a three-dimensional (3D) preform using the Chemical Vapor Infiltration (CVI) method. The preforms used as starting materials were in orthogonal fiber geometry and 3D carbon fiber knitting structure. The CVI process performed in the CVD (Chemical Vapor Deposition) device was carried out at 1250 ℃, under 2 mbar pressure, with a methane gas flow rate of 2.0 lt/min, for a total period of 312 hours gradually applied in an inert atmosphere consisting of argon and nitrogen gases. The produced block piece was processed to obtain small test samples; tensile and three-point bending tests were applied to the pieces, and their densities were measured. Samples were subjected to in-vitro biodegradation tests in 0.9 % isotonic sodium chloride solution by weight at 37 °C for a total of 21 days. The density and apparent porosity of the produced samples were measured to be 1.395 g/cm³ and 13.424%, respectively. The tensile strength and bending strength of the produced C/C composites were determined to be 252.5±6.20 MPa and 236.6±25.7 MPa, respectively. At the end of 21 days, the biodegradation ratio of C/C composites was calculated as 0.0095%. © 2025, Sakarya University. All rights reserved.Öğe Dental bioceramics: From lab to clinical practice(Nova Science Publishers, Inc., 2023) Öksüz, Kerim EmreFunctional ceramics known as bioceramics have gained significant interest in the field of regenerative medicine. They have been widely used as bone reconstructive materials in orthopedics, oral and maxillofacial surgery. One of the most commonly used materials in clinical applications are those based on calcium phosphate (Ca3(PO4)2) and calcium silicate (Ca2SiO4), which have been available on the market for several decades. Currently, there are ongoing works to develop bioceramics for various clinical applications in regenerative medicine, including dentistry. Bioceramics have shown promise in periodontal treatment, prevention of relapse, nerve regeneration, drug delivery technology, and even in esthetic medicine and cosmetics. For restorations in the anterior of the mouth, glass ceramics are an alternative approach to provide both esthetics and strength, while (Al2O3) alumina and (ZrO2) zirconia-based structural ceramics are utilized as crown cores and bridge frameworks. However, they require the application of an esthetic veneering ceramic for clinical use in tooth structure replacement. This chapter discusses the advantages of dental bioceramics, their compositions, biological evolutions, and how their physical properties relate to clinical findings. The future perspective and challenges in using bioceramics for next-generation regenerative therapy are also discussed. © 2024 by Nova Science Publishers, Inc. All rights reserved.Öğe Examination of Biological Activity of Passiflora edulis (Çarkıfelek) Extract via Phytochemical Analysis(2024) Tunc, Tutku; Sümer, Zeynep; Öksüz, Kerim Emre; Öksüz, Kerim EmreIn recent years, the use of medicinal plants as sources of drugs or herbal extracts has been of great importance. Passiflora edulis is nowadays widely studied for its antimicrobial, anticancer, and antioxidant potential. Therefore, this study aimed to determine the phytochemical structure of ethanol extract of P. edulis leaves and to investigate its biological properties such as antimicrobial and anticancer activities. The ethanol extract of P. edulis leaves was obtained and analyzed by GC-MS. The antimicrobial activity of P. edulis leaf extract was determined by MIC test. XTT method was used to determine the antiproliferative activity. In the phytochemical analysis of P. edulis extract, dodecanoic acid, tetradecanoic acid, and n-hexadecanoic acid were found the most. The antimicrobial effect of P. edulis leaf extract was found against pathogenic microorganisms. In addition, P. edulis leaf extract was found to have high anticancer activity against OvCar and MCF-7 cell lines, while it had the highest effect on the PC-3 cell line. It is thought that the effectiveness of this antiproliferative and antimicrobial activity is related to the secondary metabolites determined by GC-MS analysisÖğe Macro-Porous Aluminum Oxide-Boron Carbide Ceramics for Hard Tissue Applications(2023) Öksüz, Kerim EmreThis paper focuses on the development of high-quality bioceramic foams for the treatment of hard tissue defects, which are a widespread clinical problem worldwide. In this experimental study, ?-alumina (Al2O3) ceramics with boron carbide (B4C) additives, intended for use in biomedical applications, were produced and characterized as highly porous using the replication method. The thermal properties of open-pore polyurethane sponges, with a pore size of 20 ppi, used as an economical polymer model material, were determined by thermo-gravimetric (TGA) and derivative thermogravimetric analysis (DTG). Ceramic foams based on Al2O3, with varying B4C ratios, were obtained by high-temperature sintering and were thoroughly examined using high-resolution field emission gun scanning electron microscopy (FEG-SEM) for homogeneity, high porosity, and interconnected pore microstructure. X-ray diffraction (XRD) analyses confirmed the presence of B4C within the structure and phase changes. The compressive strength values of sintered ceramic foams containing 0%, 3%, and 5% B4C by weight were measured as 1.92 MPa, 2.05 MPa, and 2.38 MPa, respectively. In vitro tests were performed to evaluate the biological response that biomaterials intended for use in living environments would produce. Satisfactory results were obtained from cell viability experiments, demonstrating that the addition of B4C to Al2O3-based ceramic foams supports cell proliferation, which is an important advantage in hard tissue defect treatment.Öğe Microstructure of Eobania vermiculata (Müller, 1774): SEM, F-TIR and XRD Methods(2022) Öksüz, Kerim Emre; Şereflişan, HülyaIn this study, Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses are used for the microstructure characterisation of Eobania vermiculata samples collected from Iskenderun region. The shells of land snails are discarded as waste; however, they are qualified materials with multiple use areas. To substantiate this proposition, an attempt was made to elucidate the physical and chemical properties of the shells of chocolate band snail, E. vermiculata. SEM observations indicated that nacre crystals are always laminated aragonite, usually presenting sharp edges. Nacre crystallites which pile up into columns vertically abreast aligned observed. The crystals are about 390-155 nm thick, and they form stacks along a fixed spacing, filled with biological matter. The XRD and FTIR observations revealed the dominance of the aragonite form of the calcium carbonate crystal in the microstructures of each snail shell with the occurrence of different shell surface functional groups. Thus, further exploration of the shell inclusive of the organic components is required to promote its possible use as a biocomposite. Nonetheless, the present study provides an overview of physical and chemical characteristics of the land snail shells and inlight their potential use in different areas in the perspective of sustainability.Öğe Novel natural spider silk embedded electrospun nanofiber mats for wound healing(Elsevier, 2021) Öksüz, Kerim Emre; Kurt Özkaya, Neşe; Şahin İnan, Zeynep DenizIn recent years, electrospun nanofiber mats based on biopolymers have been extensively investigated for tissue and biomedical engineering, mainly because of remarkable morphological similarity with the natural extracellular matrix. The current study focuses on the preparation of novel natural spider silk (SS) embedded Poly(vinyl alcohol)(PVA)/Sodium alginate (NaAlg) wound dressings with desirable properties for a wound dressing application. The nanofibers’ surface morphology and structure were observed by a field emission scanning electron microscope (FE-SEM). In-vivo evaluation of PVA/NaAlg based electrospun nanofiber mats as a wound dressing material and their comparison to commercially available wound dressings was carried out by in-vivo tests on rabbit models. Some morphometric parameters such as counting cells, blood vessels, endothelial cells, determination of the area of the wound closure, wound healing performance, speed of wound healing and collagen thickness were investigated using OM and FE-SEM post-processing. Furthermore, in-vitro biocompatibility and cellular behavior such as adhesion and proliferation of mouse fibroblast cells (L929) were studied by XTT assay on developed nanofiber mats. The results of this experimental study indicated that the natural spider silk embedded electrospun nanofiber mat (PVA/NaAlg/SS) accelerated the rate of wound healing compared to other groups by improving the collagen formation rate, proliferative cell activity as well as decreasing the inflammatory cell amount. Furthermore, the results of the in-vivo and in-vitro experiments suggest that novel PVA/ NaAlg/SS nanofiber mats might be a fascinating bioactive wound dressing for clinical applications.Öğe Patella caerulea Kalsine Kabuklarının Mikrodalga Uygulamaları İçin Derinlemesine Analizi(Fırat Üniversitesi, 2025) Uğurlu, Erkan; Karaaslan, Muharrem; Alkurt, Fatih Özkan; Öksüz, Kerim Emre; Duysak, ÖnderBu çalışma, İskenderun Körfezi’nden toplanan Patella Caerulea kabuklarının mikrodalga radomelarında biyomalzeme olarak potansiyel uygulamasını araştırmakta ve 600-1200 °C’de kalsine edilmiş kabukların dielektrik özelliklerini incelemektedir. 10 GHz’lik merkezi frekansta, P600, P800, P1000 ve P1200 için reel dielektrik geçirgenlik değerleri sırasıyla 3,2, 2,3, 2,4 ve 2,5’tir. 10 GHz’de karşılık gelen sanal değerleri, sıcaklığa bağlı değişimleri yansıtan 0,82, 0,44, 0,52 ve 0,56’dır. Kabukların, özellikle 2,5 GHz’deki kayıp faktörü, mikrodalga laminat ve radome uygulamaları gibi iletişimde düşük kayıplı uygulamalar için potansiyellerini göstermektedir. Ayrıca, bu malzemeler bir mikrodalga sistemde alt tabaka olarak uygulanabilirliğini göstermek için geleneksel bir yama antene entegre edilmiştir. Bununla birlikte, 800 °C’yi aşan sıcaklıklarda X-ışını kırınım spektrumunda CaO tepelerinde hafif bir artış gözlemlenmiştir. Kabuk tozunun termal gravimetrik analizi ve diferansiyel termal analizi, iki ayrı aşamada oluşan ağırlık kaybını ve 125 °C ve 275 °C’de küçük endotermik tepeleri ortaya koymaktadır. Çalışma, mikrodalga anten radom malzemelerinin yüksek empedans uyumu ve düşük kayıp özellikleri nedeniyle umut verici olduğunu vurgulamaktadır. Bu araştırma, mikrodalga teknolojisi alanında ekonomik ve ekolojik faydalar için deniz kaynaklı malzemelerin keşfine katkıda bulunmaktadır.Öğe Toz metalurjisi yöntemiyle kesici uç (Soket) üretilmesi ve karakterizasyonu(Cumhuriyet Üniversitesi, 2011) Öksüz, Kerim Emre; Şimşir, MehmetSon zamanlarda, doğal taşların kesiminde elmas kesici takımların kullanımı, geniş ölçüde kabul edilen en ekonomik yöntemlerden biri oldu. Başarılı bir elmaslı kesici takımı dizaynı, yüksek kaliteli matriks tozları ile elmasların uygun seçimi ile başlar. Önemli parametrelerden bir taneside matriksin herhangi bir zarar vermeden elmas tanelerini sıkı bir şekilde tutmasıdır.Ticari soketlerin üretiminde halen Co metali kullanılmaktadır. Fe, Co metalinden daha ucuz olduğu için Co metali yerine Fe kullanılması ticari soketlerin ekonomik olarak üretimini sağlamaktadır. Üstelik Co tehlikeli bir metaldir. Bu deneysel çalışmada; Fe ve B4C ilavesinin elmas emdirilmiş Co matrisli kompozitler üzerindeki etkisi araştırılmıştır. Elmas emdirilmiş Fe-Co matrisli kompozitler toz metalürjisi yöntemiyle sıcak presleme tekniği kullanılarak üretilmiştir. B4C takviyeli ve takviyesiz 3 farklı kompozisyona (farklı Fe/Co oranı) sahip numuneler hazırlanmış, 25 MPa basınç altında ve 800?900?1000 ºC derece sıcaklıkta sinterleme işlemine tabi tutularak, B4C ve Fe takviyesinin etkisi araştırılmıştır. Kompozitlerin mekanik özelliklerinin tespiti için sertlik ölçümü yapılmış ve aşınma deneyleri de farklı yük şartlarında pim-disk türü aşınma deneyi cihazı aracılığı ile yapılmıştır. Deneysel sonuçlar; Fe ilavesi ile matriksin sertliğinin biraz azaldığını göstermiştir. Fakat B4C takviye elemanının katılmasıyla matriksin sertliğini hayli artırmıştır. B4C takviyeli Fe-Co metal matriks kompozitlerin farklı yükleme şartlarında aşınma direncinin ise; B4C takviyesiz malzemelere göre daha iyi olduğu belirlenmiştir.Üretilen kompozitlerin; Taramalı Elektron Mikroskobu (TEM) ve Enerji saçılımlı X-ray spektroskopisi (EDS) teknikleri ile karakterizasyon çalışmaları yapılmış sonuçlar açık bir şekilde tartışılmıştır.Anahtar kelimeler: Toz Metalürjisi; Bor Karbür; Kompozit; Sertlik; Aşınma.
