Yazar "Cengiz, Uğur" seçeneğine göre listele
Listeleniyor 1 - 20 / 31
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Buğulanmayan ve Işık Geçiren Süper Su-Seven Yüzey Sentezi(2015) Cengiz, UğurSüperhidrofilik (süper su-seven) yüzeyler, üzerinde su ile 5° ve altı temas açı veren yüzeyler olarak tanımlanırlar. Bu yüzeylerin buğulanmama, kendi kendini temizleme, ışığı yansıtmama gibi pratikte birçok uygulaması vardır. Örneğin, kış aylarında araba camlarında oluşan buğulanma ciddi sorunlara hatta kazalara yol açabilir. İç ve dış ortamın sıcaklık farkının yüksek olmasından dolayı iç ortamda nem düzeyi yükselir ve soğuk cam yüzeyine nem zerrecileri çarparak kondense olurlar. Buğulanma, su buharının küçük damlalar halinde cam yüzeye kondense olması ve görünür ışıkta saçılmaya neden olması ile meydana gelir. Bu istenmeyen olay günlük yaşamamızda araba camları, gözlük camları, banyo aynaları, kamera lensleri gibi birçok alanda karşımıza çıkar. Yüzeyde buğulanmayı önlemenin en basit yolu süperhidrofil bir yüzey oluşturmaktır. Böylece su damlası yüzeyde tamamen dağılacak ve ince bir film oluşturacaktır. Böylece, ışık bu film üzerinden herhangi bir saçılmaya veya bir engellemeye maruz kalmadan direk geçecektir. Bu projede, yüksek yüzey enerjili polimerler, hidrofilik silikalar ve silan bileşiklikleri kullanılarak sol-gel tekniği ile kompozit çözeltiler sentezlenmiş ve cam yüzey üzerine daldırarak, dönerek ve püskürtme teknikleri ile kaplanmıştır. Kaplama malzemesinin yapısal karakterizasyonları XRD, FTIR ve TEM cihazları ile yapılmıştır. Kaplamaların yüzey karakterizasyonları SEM, AFM ve temas açı cihazı ile yapılmıştır. Kaplamaların mekanik dayanımları, Çanakkale Seramik Arge Labartuvarlarında, çeşitli kimyasallara karşı ve mekanik bozunmaya karşı test edilmiştir. Elde edilen sonuçlara göre, bazı kaplamaların endüstriyel olarak önem taşıdığı görülmektedir ve sentezlenen ışık geçiren, süperhidrofilik ve buğulanmayan yüzeyler ile proje nihai hedefine ulaşmıştır. Proje sonuçları uluslar arası iki yayın olarak hazırlanmaktadır.Öğe Decellularization of bovine spinal cord meninges via supercritical CO2 and evaluating the extracellular matrix performance for neural tissue engineering applications(Mary Ann Liebert, Inc, 2024) Kurt, Tuğçe; Özüdoğru, Eren; Cengiz, Uğur; Derkuş, B.; Arslan, Yavuz Emre[No abstract available]Öğe Designing effective underwater self-cleaning surfaces by investigating the oil dewetting ability of hydrophobic and underwater superoleophobic Poly(Diisobutyl Glycolide)-Silica composite surfaces(Elsevier B.V., 2024) Belen, Sema Nur; Arıcan, Mehmet Onur; Mert, Olcay; Cengiz, UğurThis study introduces composite thin films of amphiphilic structures to fabricate underwater superoleophobic surfaces. The hydrophobic part of the structure is created by poly(diisobutyl glycolide) thanks to a side chain of isobutyl groups, while the hydrophilic component is formed with hydrophilic silica nanoparticles. Poly(diisobutyl glycolide), having a 77° water contact angle, was obtained through ring-opening polymerization of L-diisobutyl glycolide in a bulk medium, resulting in excellent conversion (97.9 %) and narrow polydispersity (1.47), while maintaining the chiral center. The investigation revealed a notable increment in the underwater hexadecane contact angle from 110° to 160° In contrast, the water contact angle exhibited partial constancy in the air environment because of the augmenting silica content. At a silica content reached up to 30 %, the self-cleaning underwater oil-repellent surface was accomplished, attributable to the phenomenon of the underwater Cassie state, which effectively trapped air within the hierarchical rough structure. Moreover, the surface free energy (SFE) of the composite films was evaluated using both the van Oss-Chaudary-Good and Owens-Wendt methods. Notably, the contact angle of underwater hexadecane decreased with the increase of polar interactions as determined by both methods, owing to the influence of the underwater Cassie state of the hierarchical composite surface.Öğe Development of a superhydrophobic and superoleophilic halloysite nanotube/phenyltriethoxysilane-coated melamine sponge sorbent material with high performance in supercritical CO2 atmosphere for the selective and effective oil spill cleanup and oil-water separation(Academic Press Ltd- Elsevier Science Ltd, 2025) Duman, Osman; Cengiz, Candan; Özcan Diker, Ceren; Cengiz, Uğur; Güresir, Süleyman Mert; Tunç, SibelIn this study, activated halloysite nanotube (HNT) and phenyltriethoxysilane (PTES) were utilized for the first time to fabricate modified HNT materials and coat them onto melamine sponge (MS) substrate in the supercritical carbon dioxide (scCO2) atmosphere. The successful coating of MS substrate was confirmed using SEM, EDS, XPS, and contact angle measurements. The drainage technique applied in the CO2 medium achieved the uniform coating of both the inner and outer surfaces of the MS. Water and oil contact angles of the fabricated sorbent material (MS-PTES) were measured as 167.1 degrees and 0 degrees, respectively. MS-PTES sorbent having superhydrophobic and superoleophilic properties demonstrated sorption capacities ranging from 47.6 g/g to 132.2 g/g for 13 different pollutants, including various petroleum products, oils, and organic solvents. Moreover, the MSPTES sorbent material showed outstanding separation efficiency (99.99%) for the diesel-water mixture using a continuous separation process. It also displayed high selectivity for oil and organic solvent pollutants under acidic, saline, and alkaline conditions, along with excellent reusability, chemical stability, robustness, and mechanical flexibility. MS sorbent material coated with HNT-modified PTES nanoparticles, produced in the scCO2 atmosphere using the drainage technique, represents a promising solution for the removal of petroleum derivatives, oils, and organic solvents from water.Öğe Development of plant-based biopolymer coatings for 3D cell culture: boron-silica-enriched quince seed mucilage nanocomposites(Royal Society of Chemistry, 2023) Yılmaz, Hilal Deniz; Cengiz, Uğur; Derkuş, Burak; Arslan, Yavuz EmreSpheroid formation with spontaneous aggregation has captured interest in most cell culture studies due to its easy set-up and more reliable results. However, the economic and technical costs of the advanced systems and commercial ultra-low adhesive platforms have pushed researchers into pursuing alternatives. Nowadays, polymeric coatings, including poly-hydroxyethyl methacrylate and agar/agarose, are the commonly used polymers for non-adhesive plate fabrication, yet the costs and working solvent or heat-dependent preparation procedures maintain the need for the development of novel biomaterials. Here, we propose a greener and more economical approach for producing non-adherent surfaces and spheroid formation. For this, a plant waste-based biopolymer from quince fruit (Cydonia oblonga Miller, from Rosaceae family) seeds and boron-silica precursors were introduced. The unique water-holding capacity of quince seed mucilage (Q) was enriched with silanol and borate groups to form bioactive and hydrophilic nanocomposite overlays for spheroid studies. Moreover, 3D gel plates from the nanocomposite material were fabricated and tested in vitro as a proof-of-concept. The surface properties of coatings and the biochemical and mechanical properties of the nanocomposite materials were evaluated in-depth with techniques, and extra hydrophilic coatings were obtained. Three different cell lines were cultured on these nanocomposite surfaces, and spheroid formation with increased cellular viability was recorded on day 3 with a >200 μm spheroid size. Overall, Q-based nanocomposites are believed to be a fantastic alternative for non-adherent surface fabrication due to their low-cost, easy operation, and intrinsic hydration layer forming capacity with biocompatible nature in vitro.Öğe Effect of alkoxysilane chain length on the surface, stability, sorption and oil-water separation properties of novel superhydrophobic porous sorbent materials produced using innovative drainage technique in scCO2 atmosphere(Elsevier, 2024) Duman, Osman; Cengiz, Candan; Özcan Diker, Ceren; Cengiz, Uğur; Güreşir, Süleyman Mert; Tunç, SibelAlkoxysilanes play an important role in the development of new superhydrophobic sorbent materials with high sorption capacity for the cleanup of oil spills from water. Here, three different alkoxysilanes with 1, 8 and 16 carbon (C) chains were used for the first time to elucidate the role of alkoxysilanes and to determine the relation between the functional alkyl chain length of alkoxysilane compound within the coating formulation and the surface, sorption and separation properties of novel superhydrophobic sorbent materials fabricated in scCO2 atmosphere. Both the modification of activated halloysite nanotube (HNT) with each methyltrietoxysilane (METES), octyltriethoxysilane (OTES) and hexadecyltrimethoxysilane (HDTMS) separately and the direct fabrication of melamine sponge (MS)-HNT/alkoxysilane hybrid composite sorbents (MS-METES, MS-OTES and MS-HDTMS) were achieved by innovative drainage technique in scCO2 atmosphere. The surface properties of superhydrophobic sorbents were examined using contact angle, SEM, EDS, FTIR, XPS and 29Si-MAS NMR techniques. Maximum sorption capacity of melamine sponge-based hybrid materials decreased from 122.2 g/g to 90.4 g/g as the chain length of alkoxysilane was increased from C1 to C16. Water contact angle, density and porosity of superhydrophobic MS-METES, MS-OTES and MS-HDTMS sorbents were determined to be 153.0 degrees, 13.56 mg/cm3 and 99.10 %; 159.4 degrees, 16.58 mg/cm3 and 98.90 %; and 165.4 degrees, 18.90 mg/cm3 and 98.75 %, respectively. All sorbents exhibited excellent thermal stability, good chemical stability, good robustness, and high mechanical durability. Experimental results revealed that the novel coating technique applied to porous MS have a significant potential for the direct fabrication of new superhydrophobic and superoleophilic sponge-based sorbent materials.Öğe Effect of deposition charges on the wettability performance of electrochromic polymers(Elsevier, 2015) Çağlar, Aysel; Cengiz, Uğur; Yıldırım, Mehmet; Kaya, İsmetElectrochromic polymers have been designed as future candidates for electrochromic displays (ECDs) and smart windows. This class of conducting polymers has been studied with their several optical properties as well as spectroelectrochemical stabilities. In practical use their contamination and abrasion could be expected to be main problem as exposed to moisture and other possible pollutants. In this study, we present a perspective to well-known electrochromic polymers in the words of their durable use. For this aim, a series of electrochromic polymers are deposited on indium tin oxide (ITO) coated glass plates by bulk electrolysis. Polymeric films are deposited by varied deposition charges (Q(s)) ranging from 62 to 620 mC cm(-2) for comparison. Equilibrium water contact angle (theta(equ)(water)) measurements of the prepared surfaces are measured by Attention Theta Optical Tensiometer. Surface roughness parameters (RMS) are determined by atomic force microscopy (AFM) technique and used for interpretation of hydrophobic-hydrophilic characteristics. The results clearly indicate that; poly(ethylenedioxythiophene) (PEDOT) has a hydrophilic surface whose hydrophilicity is increased by applied deposition charge and becomes a superhydrophile at high deposition charges. Among the tested polymers polycarbazole (PCarb) is the most promising long lifetime candidate due to its relatively hydrophobic character. Also, the hydrophobicity of PCarb is linearly increased by increasing deposition charge and reaches an optimum point at a particular condition. (C) 2015 Elsevier B.V. All rights reserved.Öğe Fabrication and characterization of metakaolin-based fiber reinforced fire resistant geopolymer(Elsevier, 2023) Akarken, Gürkan; Cengiz, UğurGeopolymers have many advantages over Portland cement, such as low energy cost, reduced greenhouse gas emissions, high compressive strength, high-temperature stability, low thermal conductivity, and high strength at an early age. This study obtained fiber-reinforced geopolymer composite (FRGC) structures using metakaolin (MK) basalt and glass fiber, and the fire-resistant FRGC structure was developed. The morphology, structure, and thermal characterization of fire-resistant FRGC were obtained using SEM, TEM, XRD, XRF, FTIR, and TGA. As a result of SEM, FT-IR, and TGA analyses, it was observed that high-temperature geopolymer samples retained their stable structure. The SEM images also indicated the fiber's effect on preventing surface cracking. Fireresistant properties were tested by heat exposure in a muffle furnace for thermal behavior of 200, 400, and 800 degrees C. The mechanical stability of the FRGC blocks was tested using the compression test before and after exposure to high temperatures. In this test, the FRGC block, kept for one hour at 200 degrees C, still has the compressive strength at the high strength concrete class and can be used in skyscrapers (51-76 MPa).Öğe Fabrication of Self-Cleaning Perfluoroacrylate Blend Films by Spray Coating Method(Çanakkale Onsekiz Mart University, 2023) Ünzal, Özge; Belen, Sema Nur; Cengiz, UğurThe superhydrophobic surfaces are contained two essential principles. First, low surface energy polymers, such as fluoropolymers pushing the liquid onto the surface are necessary. The surface roughness is the second necessity to obtain superhydrophobicity, providing air packets between the roughness and reducing surface interaction with the liquid. This study fabricated the superhydrophobic blend coating using a spray coating method. The flat surface of PFMA homopolymer synthesized in scCO2 medium was fabricated free meniscus coating method due to the lack of solubility in the conventional solvent. To overcome the solubility problems of the PFMA, the p(Perfluoromethacrylate-ran-Styrene) copolymer was fabricated in a scCO2 medium. Blend solutions are prepared to reduce costs and provide high hydrophobicity by using p(Perfluoromethacrylate-ran-Styrene) copolymer and PS homopolymers. The surface roughness of the blend films was altered using silica nanoparticles coated on a glass slide by a spray coating. The surface morphology was characterized by SEM analyses indicating that double-scale surface morphology was obtained by increasing the SNp of the composite solution. The water contact angle indicated that the superhydrophobic rough surface was obtained with TMS70 and PS blend formation having 33.0 % PS and 12.5% silica nanoparticles.Öğe Fabrication of superhydrophilic TEOS-lactic acid composite films and investigation of biofouling behaviour(Kare Publishing, 2022) Ervan, Tuğçe; Küçüker, Mehmet Ali; Cengiz, UğurPhytoplankton and diatom microalgae species cause biofouling by adhering to the surfaces, especially in closed cultivation systems such as tubular photobioreactors. This biofilm formation blocks the sunlight; after harvesting, it is necessary to clean the reactor. This cleaning process causes loss not only in time and finance but also in terms of environmental pollution due to using toxic chemicals and excess water usage. This study aimed to investigate the reduction of the microorganism cell adhesion on the hybrid surface. To succeed in this, the composite surface of tetraethoxysilane (TEOS) and lactic acid (LA) was prepared by the sol-gel process. Then the hybrid surfaces were coated on glass slides by the dip coating method. The wettability performance of the TEOS-LA hybrid surface was investigated using contact angle measurement and light transmittance. The wettability result showed that the super hydrophilic surface having 54 mJ/m2 of surface free energy values was obtained. Furthermore, the increased lactic acid content of the composite films increased the surface free energy (SFE) values, decreasing the water contact angle. A pencil hardness test characterized the mechanical strength of the surfaces, and it was determined that the hardness of the composite films was decreased by increasing the LA content of the composite films. Resultantly, it is found that the TEOS-LA superhydrophilic composite film reduces the adhesion of microalgae. © 2022, Kare Publishing. All rights reserved.Öğe Fabrication of superhydrophobic and highly oleophobic electrochromic composite surfaces(Elsevier Science Sa, 2016) Yıldırım, Mehmet; Demir, Gülizar Elif; Çağlar, Aysel; Cengiz, Uğur; Kaya, İsmetMechanically stable, superhydrophobic and highly oleophobic polymeric electrochromic (EC) composite surfaces were prepared. Firstly, an acrylate-based terpolymer with perfluoroalkyl side chains was synthesized as surface tension reducing component of the composite surfaces. Before the use, pre-synthesized terpolymer was gelled to gain higher mechanical stability. Obtained conducting gel was added into the electropolymerization media including 3,4-ethylenedioxythiophene (EDOT) or pyrrole (Py) monomers dissolved in an electrolyte solution. Electrodeposition time was varied to optimize the surface wettability characteristics. Water contact angles (WCA) and salad oil contact angles (OCA) were determined by Attension Theta Optical Tensiometer. WCA and OCA of flat surfaces were quite lower than those of the EC composite surfaces with high surface roughness caused by poly (3,4-ethylenedioxythiophene) (PEDOT) component. PEDOT and PPy components have provided not only EC properties but also surface roughness that particularly increases WCA and OCA. (C) 2016 Elsevier B.V. All rights reserved.Öğe Fabrication of superhydrophobic melamine sponge composite sorbent in supercritical carbon dioxide atmosphere for selective and effective oil removal from water(Elsevier Sci Ltd, 2023) Duman, Osman; Cengiz, Uğur; Özcan Diker, Ceren; Cengiz, Candan; Güreşir, Süleyman Mert; Tunç, SibelIn this study, both the modification of activated halloysite nanotube (HNT) with methyltriethoxysilane (METES) and the fabrication of durable, superhydrophobic (water contact angle: 153.0 degrees) and superoleophilic (oil contact angle: 0 degrees) melamine sponge (MS)-HNT-METES sorbent material (MS-METES) were achieved in supercritical carbon dioxide (scCO2) atmosphere. For the coating of MS with clay mineral and METES through sol-gel reaction in scCO2, optimal process conditions were determined to be pressure difference of 60 bars at 35 degrees C, solvent/ METES mass ratio of 7.5, METES/MS mass ratio of 10, and degas time of 400 s. Successful preparation of MSMETES was proven by XPS, FTIR, 29Si-MAS NMR, SEM, and contact angle measurements. MS-METES displayed excellent sorption capacity for various petroleum products, oils, and organic solvents (49.6-122.4 g/g), remarkable oil-water separation efficiency (99.1%, for continuous separation technique), high selectivity for oil/ organic solvent in acidic, salty, and alkaline solution conditions, good reusability, chemical stability and robustness, and outstanding flexibility and mechanical stability. We believe that the innovative process used in this study will have great potential to be used by researchers in the direct fabrication of new superhydrophobic and superoleophilic sorbent materials for the selective removal of oil and organic solvent spills from water.Öğe Fabrication of superhydrophobic sorbent material via in-situ coating of melamine sponge with halloysite nanotube and fluoroalkylsilane using supercritical CO2 coating system for efficient oily water treatment(Elsevier, 2025) Duman, Osman; Cengiz, Uğur; Özcan Diker, Ceren; Güresir, Süleyman Mert; Tunç, Sibel; Cengiz, CandanThis study presents the preparation of a novel sorbent material with high performance and special wettability for oily water treatment, utilizing halloysite nanotube (HNT) and perfluorooctyl triethoxysilane (PFOTES). Fluoroalkyl silanes, such as PFOTES, offer significant advantages over other monomers and alkoxysilanes due to their superior water-repellent properties and high solubility in CO2 atmosphere, enabling homogeneous polymerization and coating. The modification of PFOTES with HNT was successfully achieved in the supercritical CO2 (scCO2) environment at 35 degrees C and 125 bar using a sol-gel technique. Subsequently, HNT-modified PFOTES nanoparticles were coated onto melamine sponge (MS) via a drainage technique, marking the first application of this method to create a superhydrophobic (WCA: 165.2 degrees) and superoleophilic (OCA: 0 degrees) sorbent material (MSPFOTES). The MS-PFOTES sorbent material, produced via a one-step, two-pot coating method, demonstrated exceptional sorption capacities ranging from 39.1 to 117.5 g/g for oily pollutants / organic solvents. Additionally, MS-PFOTES achieved an outstanding separation efficiency of 99.99 % for diesel-water mixtures in continuous separation processes. The fabricated material also exhibited remarkable thermal stability, chemical resistance, and robustness. Experimental findings obtained in this study highlight the significant potential of this innovative coating technique for the direct preparation of sorbent material with special wettability for oily water treatment.Öğe From a plant secretion to the promising bone grafts: Cryogels of silicon-integrated quince seed mucilage by microwave-assisted sol-gel reaction(Elsevier B.V., 2021) Yılmaz, Hilal Deniz; Cengiz, Uğur; Arslan, Yavuz Emre; Kıran, Fadime; Ceylan, AhmetDesign and fabrication of biologically active cryogels using novel biopolymer(s) are still of great importance at regenerating bone defects such as traumatic bone injuries, maxillofacial surgery, osteomyelitis, and osteoporosis. Nowadays, plant mucilage, an herbal biomaterial, has been drawn attention by scientists due to their marvelous potential to fabricate 3-dimensional (3D) physical constructs for the field of regenerative medicine. Herein, a 3D cryogel from silicon-integrated quince seed mucilage (QSM) is constructed using microwave-assisted sol–gel reaction, characterized in-depth by attenuated total reflectance Fourier transform-infrared spectroscopy (ATR-FTIR), solid-state silicon cross-polarization magic-angle nuclear magnetic resonance (29Si-CP-MAS NMR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), micro-mechanical testing, porosity, and swelling tests, contact angle measurements, Brunauer-Emmet-Teller and Barret-Joyner-Halenda (BET-BJH) analysis, enzymatic biodegradation test, and field emission-scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM-EDX) mapping. The osteobiologic capacity of the cryogels is determined using human adipose-derived mesenchymal stem cells (hAMSCs) under in vitro conditions. Osteogenic differentiation of hAMSCs on both QSM and silica-modified QSM (Si-QSM) cryogels is analyzed by histochemistry, immunohistochemistry, and quantitative-real time (q-RT) PCR techniques. The results obtained from in vitro experiments demonstrate that the upregulation of osteogenesis-related genes in Si-QSM cryogels presents a stronger and earlier development over QSM cryogels throughout the culture period, which in turn reveals the great potential of this novel Si-incorporated QSM cryogels for bone tissue engineering applications.Öğe Hydrothermal Synthesis of CuO Nanoparticles: Tailoring Morphology and Particle Size Variations for Enhanced Properties(Çanakkale Onsekiz Mart University, 2024) Akarken, Gürkan; Cengiz, Uğur; Bektaş, Tijen EnnilTransition metal oxides, particularly copper oxides, have garnered significant attention due to their intriguing photochemical, photomagnetic, photo-thermal, and photoconductive properties. Among these, CuO stands out as a p-type semiconductor having narrow bandgap energy ranges from 1.2 to 2 eV, finding versatile applications such as gas sensing, magnetic storage, solar energy conversion, photocatalysis, supercapacitors, field-emission emitters, and optical switches. Additionally, it serves as a crucial component in materials designed for lithium-ion electrodes. In this study, five different CuO nanoparticles were synthesized by simple and cost-effective hydrothermal method with various reaction temperatures and times in a teflon lined stainless steel autoclave. Copper (II) chloride dihydrate was used as copper source in this process. Various characterization techniques were conducted including X-ray powder diffraction (XRD), Raman spectroscopy, and transmitting electron microscopy (TEM). The effect of temperature and time on synthesis process was characterized and discussed. TEM images show that particle size of CuO increase with the temperature and reaction time. First reaction had the smallest particle sizes (mostly around 9-11 nm). This can be attributed to its lowest reaction temperature and shortest reaction time. For the other reactions, two of them accumulate around 19-35 nm and two around 27-45 nm range. However, the rise in the particle’s diameters is not directly proportional to temperature and time. As a result, CuO nanoparticles have been produced with simple method for the market. It can be produced in large quantities for heat exchangers, gas sensing, magnetic storage, solar energy conversion, photocatalysts, supercapacitors, etc.Öğe Innovative Geopolymer Tiles for Indoor Humidity Control: A Comparative Study of Moisture Buffering Performance(Amer Chemical Soc, 2025) Akarken, Gürkan; Yıldırım, Yıldız; Cengiz, UğurGeopolymers have attracted increasing attention due to their unique properties in the construction industry. In this work, innovative geopolymer tiles were evaluated regarding their potential to control indoor relative humidity as a passive construction material. Our production process systematically develops geopolymer tiles with elevated moisture buffering capabilities using four distinct metakaolins and one commercial metakaolin to make a comparison. A critical metric for evaluating hygroscopic materials' capacity to control the indoor humidity change is the moisture buffer value (MBV). The geopolymer tiles' MBV was determined by the Nordtest method in a controlled climate chamber. Additionally, a custom-designed moisture buffer test and strength measurements were conducted, including inspections of the physical appearance after the tiles were submerged in water for 7 days. The results indicate that the geopolymer tiles exhibit exceptional moisture buffering performance, with MBV values ranging between 5.68 and 7.94 (g/m2 Delta%HR). These are the highest and one of the first values for geopolymer tile moisture buffer values in the literature so far. The text discusses the advantages and superior performance of these tiles compared with conventional methods, supported by mechanical, morphological, and structural analyses.Öğe Kendi kendini temizleyen yağ itici cam ve seramik yüzeylerin sentezi(2017) Cengiz, UğurBir yüzeyin kendi kendini temizleme özelliği yüzeyin sıvıya karşı süper itici özellik taşıması ve sıvının ilerleyen ve gerileyen temas açı farkının (CAH, temas açısı karmaşası) veya sıvının kayma açısı değerinin (TA, Tilt angle) 10o ve altı değere sahip olması ile meydana gelir. İdeal, düz mono-tabaka bir yüzeyde CAH değeri sıfırdır, ancak pratikte her yüzeyde var olan pürüzlülükten, yüzeydeki kimyasal heterojenlik veya kirlilikten dolayı bir CAH değeri vardır. Yağ damlası ile kirlenmeyen Süperoleofobik (süper yağ-itici) yüzeyler, üzerinde düşük yüzey enerjili organik hidrokarbon çözücülerin 150°? den büyük temas açısı veren yüzeyler olarak tanımlanır. Bu yüzeylerin hava veya su içindeki organik veya biyolojik maddelerin sebep olduğu kirlenmeyi önlemek gibi pratikte birçok uygulaması vardır. Bu tip yüzeylerin sentezinde iki önemli prensip geçerlidir: Öncelikle, düşük yüzey enerjili bir yüzey oluşturmak gerekir; ikinci olarak da pürüzlülüğü yüksek ve hava paketçiklerinin bu pürüzler içinde barındığı bir yüzey oluşturulmalıdır. Ancak yüksek pürüzlülük düşük mekanik dayanıklılığa neden olur. Bu yüzden kendi kendini temizleyen yüzeylerde, yüksek pürüzlülük ile yüksek temas açı yerine pürüzsüz ancak yüzeyden kayan düşük kayma açılı yüzeyler ?dinamik sıvı itici yüzeyler? daha çok tercih sebebidir. Dinamik yağ itici yüzeylerin süperoleofobik yüzeylere göre avantajı düşük pürüzlülükten kaynaklı hem daha yüksek mekanik dayanım hem de daha ucuza sentezlenebilmesidir. Projenin amacı zeytinyağı, ayçiçeği yağı, süt, çay ve kahve damlaları gibi günlük hayatta sıklıkla karşılaşılan kirleticilere karşı kirlenmeyen ve ışık geçiren bir yüzeyin sentezini içerir. Projede amaçlanan ışık geçiren ve yağ damlası gibi kirleticilerle kirlenmeyen, kendi kendini temizleyen FAS+siloksan ve FAS+siloksan+hidrofobik silika kompozit yüzeyler sol-gel tekniği ile üretilmiştir. Proje sonunda, sentezlenen cam ve seramik üzerine kaplanan bu kompozit filmler ile yağ damlalarına karşı kendi kendini temizleme özelliği kazanılmış ve mekanik ve kimyasal problemim üstünde gelinmiştirÖğe Mechanically stable superhydrophilic antifog surface by microwave assisted sol-gel method(Elsevier B.V., 2021) Okkay, Hikmet; Satı, Sadık; Cengiz, UğurIn this study, optically transparent and mechanically stable of superhydrophilic composite thin films were fabricated via a low-cost one-step one pot microwave-assisted sol-gel technique. The microwave reaction time was optimized according to surface characterization of homo TMOS surfaces. The reaction time was arranged as 17.5 min having low cost compared to the conventional sol-gel technic. The wettability performance and antifogging behavior of PVA-TMOS composite films were investigated according to variation of the PVA content. The static contact angle values of the composite surfaces were found to vary between 30o and 5o. Superhydrophilic surface having tilt angle is 9o showed a good antifogging performance. Mechanical durability of the composite surface was also characterized by scratching and adhesive tape test. In addition, the time depending water contact angle was also measured for 100 days. It is found that TMPV96 composite film having 0.096 (wt,%) content of PVA showed higher mechanical performance with transparent superhydrophilic surface.Öğe Mikroyosun Üretiminde Biyolojik Olarak Kirlenmeyen Akıllı Fotobiyoreaktör Üretimi(2023) Cengiz, Uğur; Haznedaroğlu, Berat Zeki; Küçüker, Mehmet Ali; İpsalalı, Özde; Belen, Sema Nur; Durmaz, Fatma Gülçin; Güneş, KaniyeDünyamızda son zamanlarda karşılaşılan doğa olayları, iklim değişiklikleri ve bunlara ek olarak son pandemi süreci insanoğluna sürdürülebilir gıdanın önemi ve gerekliliğini net bir şekilde hatırlatmıştır. Bu yüzden alternatif sürdürülebilir gıda kaynaklarına olan arayış son zamanlarda bilim insanlarının ilgi odağı haline gelmiştir. Yosunlar gün ışığı altında fotosentez yaparak açık ve kapalı sistemlerde üretilebilir. Gıda ve ilaç gibi saf ürünlerin üretilmesinde tür çeşitliğinin kontrolü açısından kapalı sistemlere ihtiyaç vardır. Ancak, kapalı sistemlerde mikroyosunların büyümesi sırasında reaktör yüzeyine yapışıp biyofilm oluşturma gibi bir dezavantajı vardır. Biyofilm oluşumu da güneş ışınının reaktör içerisine girmesini engeller. Ayrıca, biyofilm varlığı hasat sonrası reaktörün bazı kimyasallar ile temizlenmesi gerekliliğini ortaya çıkarmaktadır. Reaktörün temizliği hem zaman hem de maddi kayıpla birlikte temizlik esnasında kullanılan kimyasalların ve fazla su tüketimi yüzünden çevre kirliliğine neden olmaktadır. Bu problem, mikroyosun üretiminde kullanılan reaktör yüzeyinin modifiye edilerek, üretim sırasında yosunların bu yüzeye yapışması engellenerek çözülebilir. Bu projede yapısında OH grupları olan yüksek yüzey enerjili monomerler ve polimerlerden oluşan yeni Ormosil kaplamalar üretilmiştir. Bu kaplamalar daldırma tekniği ile mikroskop camı yüzeyi kaplayıp açık havada hidrofilik, su altında süperoleofobik yüzeyler üretilmiştir. Mekanik ve kimyasal testlerden geçen yüzeyler, biyopolimer içeriği fazla, tatlı su mikroyosunları olan Chlorella vulgaris, Chlorella sorokiniana, Ettlia oleoabundans ve deniz suyu türü olan Nannochloropsis sp ile adezyon testine tabi tutulmuştur. Bu test yüzeyin hasat süresince mikroyosun içerisinde bekletilip her geçen gün yüzeyde oluşan biyofilm miktarının ölçülmesi ile yapılacaktır. Yapılan deneysel ve model sonuçları karşılaştırılarak mikroyosun yapışmasını engelleyen en iyi yüzey sentezi sonucunda proje nihai hedefi olan ?mikroyosunlara karşı biyolojik olarak kirlenmeyen ve hasat sonrası temizlenme ihtiyacı duyulmayan akıllı reaktör tasarımı? için fotobiyotakörler özel bir düzenekte daldırma tekniğinin tersi bir şekilde kaplanmıştır. Daha sonra kaplanmış ve kaplanmamış PBR içerisinde seri mikroyosun üretimi yapılmıştır. Yapılan çalışmalar sonunda en fazla protein içeriği olan Chlorella vulgaris? in seri üretiminde modifiye fotobiyoreaktörün kaplanmamışa göre % 50 daha az kirlendiği bulunmuştur. Proje Çanakkale Onsekiz Mart Üniversitesinde yürütülmüştür. Proje danışmanı Boğaziçi Üniversitesi, Çevre Bilimleri Enstitüsü öğretim üyesi ve aynı zamanda İstanbul Mikroyosun Biyoteknolojileri Araştırma ve Geliştirme Birimi Müdürü Dr. Öğr. Üyesi Berat Z. Haznedaroğlu?dur. Kendisi kullanılması planlanan mikroyosun türleri için saf türün sağlanmasında ve tecrübe aktarımında proje ekibine destek olmuştur. Proje araştırmacısı Dr. Öğr. Üyesi Mehmet Ali Küçüker, uzmanlık alanı mikroyosun üretimi ve teknolojileri üzerinedir. Kendisi cam kaplamaların ve sonrasında fotobiyoreaktörlerin mikroyosun türlerine karşı yapışma testlerini yapmıştır. Proje yürütücüsü polimer sentezi ve uygulamaları ile polimerik yüzeylerin ıslanabilirlik davranışları üzerine uzmandır. Kendisi tüm kaplama çözeltilerinin üretilmesinde ve kaplamların yapılmasında, ıslanabilirlik testleri ile mekanik ve kimyasal datanım testlerin yapılmasından sorumludur. Önerilen bu projede bir lisans (star bursiyer) bir yüksek lisans (Ocak ayında mezun olacak) ve iki de doktora öğrencisi (biri biyolojik kirlenme üzerinde diğeri polimer sentezi ve karakterizasyonu üzerinde) çalışmışlardır.Öğe Multilayer electrochromic surfaces derived from conventional conducting polymers: Optical and surface properties(Elsevier Science Bv, 2015) Demir, Gülizar Elif; Yıldırım, Mehmet; Cengiz, Uğur; Kaya, İsmetIn this study, some kinds of multilayer (double and triple) electrochromic (EC) surfaces were prepared using layer-by-layer (LBL) electrodeposition techniques. Polypyrrole (PPy) was deposited as the first layer and the upper layers were changed. EC characteristics were investigated by spectroelectrochemical measurements. Surface roughness parameters (Root Mean Square-RMS) were determined using atomic force microscopy (AFM) technique. The results showed that different color options may be obtained by altering LBL deposition of EC polymers. Equilibrium water contact angle (circle minus(equ)(water)) measurements showed that incorporation of hydrophilic poly(3,4-ethylenedioxythiophene) PEDOT in LBL EC surfaces resulted in a decrease in the contact angle. However, the circle minus(equ)(water) of multilayer films increased with the incorporation of the hydrophobic polycarbazole (PCarb) layer. (C) 2015 Elsevier B.V. All rights reserved.
