Kenan Yıldırım

Prof. Dr. Kenan Yıldırım

orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 July 2023 in Journal of Industrial and Engineering Chemistry
Verified
Journal Article
Closed access
SSShamim Sheikh
Shamim Sheikh
MRMahmudur Rahman
Mahmudur Rahman
SRSafiur Rahman
Safiur Rahman
KYKenan Yıldırım
Kenan Yıldırım
MMMohd. Maniruzzaman
Mohd. Maniruzzaman

19 October 2021 in Polymers
Verified
Journal Article
Open access
PDF file
FPFatma Nur Parın
Fatma Nur Parın
Sana UllahSana Ullah
Sana Ullah
KYKenan Yıldırım
Kenan Yıldırım
MHMotahira Hashmi
Motahira Hashmi
Ick Soo KimIck Soo Kim
Ick Soo Kim
The fabrication of skin-care products with therapeutic properties has been significant for human health trends. In this study, we developed efficient hydrophilic composite nanofibers (NFs) loaded with the folic acid (FA) by electrospinning and electrospraying processes for tissue engineering or wound healing cosmetic applications. The morphological, chemical and thermal characteristics, in vitro release properties, and cytocompatibility of the resulting composite fibers with the same amount of folic acid were analyzed. The SEM micrographs indicate that the obtained nanofibers were in the nanometer range, with an average fiber diameter of 75–270 nm and a good porosity ratio (34–55%). The TGA curves show that FA inhibits the degradation of the polymer and acts as an antioxidant at high temperatures. More physical interaction between FA and matrices has been shown to occur in the electrospray process than in the electrospinning process. A UV-Vis in vitro study of FA-loaded electrospun fibers for 8 h in artificial acidic (pH 5.44) and alkaline (pH 8.04) sweat solutions exhibited a rapid release of FA-loaded electrospun fibers, showing the effect of polymer matrix–FA interactions and fabrication processes on their release from the nanofibers. PVA-CHi/FA webs have the highest release value, with 95.2% in alkaline media. In acidic media, the highest release (92%) occurred on the PVA-Gel–CHi/sFA sample, and this followed first-order and Korsmeyer–Peppas kinetic models. Further, the L929 cytocompatibility assay results pointed out that all NFs (with/without FA) generated had no cell toxicity; on the contrary, the FA in the fibers facilitates cell growth. Therefore, the nanofibers are a potential candidate material in skin-care and tissue engineering applications.

1 March 2014 in e-Polymers
Verified
Journal Article
Open access
KYKenan Yıldırım
Kenan Yıldırım
YUYusuf Ulcay
Yusuf Ulcay
In this study, macromolecular arrangements in fibers were investigated and a novel approach based on model development for partially oriented (POY) polyethylene terephthalate (PET) yarn morphology was proposed. Differential scanning calorimeter (DSC) analysis, Fourier transform infrared (FT-IR) analysis, boiling water shrinkage and tensile tests were performed through the study. DSC thermogram, FT-IR spectra, stress-strain curve, the change in the boiling water shrinkage properties and data from the literature were used to develop the model for POY PET fiber morphology. In order to make a comparison, textured PET yarn morphology was also investigated. The neck formations during tensile tests, cold crystallization on the DSC thermogram, peak formation on the FT-IR spectrum of the POY PET yarn after texturizing and shrinkage test at 971 and 845 cm-1 and shrinkage phenomenon have been explained by this model.

1 September 2017 in Journal of Engineered Fibers and Fabrics
Verified
Journal Article
Closed access
KYKenan Yıldırım
Kenan Yıldırım
HOHamdi Ogut
Hamdi Ogut
YUYusuf Ulcay
Yusuf Ulcay
In the manufacture of yarn, predicting the effect of changing production conditions is vital to reducing defects in the end product. This study compares, for the first time, non-linear regression and artificial neural network (ANN) models in predicting 10 yarn properties shaped by the influence of winding speed, quenching air temperature and/or quenching air speed during production. A multilayer perceptron ANN model was created by training 81 patterns using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. The hyperbolic tangent, or TanH, activation function and logistic activation functions were used for the hidden and output layers respectively. Results showed that the ANN approach exhibited a greater prediction capability over the nonlinear regression method. ANN simultaneously predicted all of the 10 final properties of a yarn; tensile strength, tensile strain, draw force, crystallinity ratio, dye uptake based on the colour strengths (K/S), brightness, boiling shrinkage and yarn evenness, more accurately than the non-linear regression model (R2=0.97 vs. R2=0.92). These results lend support to the idea that the ANN analysis combined with optimization can be used successfully to prevent production defects by fine tuning the production environment.

11 June 2020 in Research Square
Verified
Preprint
Open access
PDF file
FPFatma Nur Parın
Fatma Nur Parın
ÇAÇiğdem İnci Aydemir
Çiğdem İnci Aydemir
GTGökçe Taner
Gökçe Taner
KYKenan Yıldırım
Kenan Yıldırım
Nanofibers with bioactive agents are good candidates for skin-care applications due to high spesific surface area, low density and highly porous structure. In this study, hydrophilic based bioactive nanofibers were produced via an electrospinning and electrospraying simultaneous process. Polyvinyl alcohol (PVA), polyvinyl alcohol-gelatin (PVA-Gel) and polyvinyl alcohol-alginate (PVA-Alg) polymers were used as the matrix material and folic acid (FA) particles were dispersed simultaneously on the surface of these hydrophilic nanofibers. The morphology of the nanofibers (NFs) was uniform and dispersed folic acid particles incorporated into the structure of nanofibers as confirmed by scanning electron microscopy (SEM). Thermal behavior, chemical structure of the composite nanofibers were analyzed/investigated by thermogravimetric analysis (TGA) and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) which showed that no chemical bonding between vitamin and polymers. A controlled release of FA-loaded electrospun fibers were carried out by UV-Vis in vitro study within the 8 hour-period in artificial sweat solutions (acidic media, pH 5,44). The obtained PVA/FA, PVA-Gel/FA and PVA-Alg/FA fibers released 49.6 %, 69.55 % and 50.88 % of the sprayed FA in 8 h, indicating the influence of polymer matrix and polymer-drug interactions, on its release from the polymer matrix. Moreover, biocompatibility of all developed novel NFs was assessed by two different cytotoxicity tests,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and neutral red uptake (NRU) assay in L929 cell lines. In all cases, it is clearly concluded that these new electrospun fibers had fast-release of the vitamin and the hybrid process is suitable for transdermal patch applications, especially for skin-care products. Moreover, it has been proposed nanofiber with folic acid as a patch may prevent the COVID-19. The results of cytotoxicity assays on L929 cell reveal that all prepared NFs have no or slight cell toxicity. PVA and PVA-Gel with/without FA nanofibers seems more biocompatible than PVA-Alg nanofibers.

18 December 2019 in Material Science Research India
Verified
Journal Article
Open access
PDF file
GAGulsum Aydin
Gulsum Aydin
KYKenan Yıldırım
Kenan Yıldırım
AKAyse Kalemtas
Ayse Kalemtas
In this study, a simple, innovative approach is applied to produce porous a-TCP-CeO2-Al2O3 composite beads via using bovine bone-derived hydroxyapatite, cerium oxide, and alumina ceramics. Bovine-bone derived hydroxyapatite was obtained via calcination of bones at 950°C for 3 hours. Hydroxyapatite is a thermally unstable biomaterial at high temperatures, and depending on its stoichiometry decomposes at 800-1200°C. Sodium alginate was successfully used as an in situ gelling templates for the production of the ceramic beads and starch, an environmentally friendly and economic pore-forming agent, is used to achieve interconnected, highly open porosity containing composite beads. Sintering of the ceramic−starch−alginate green composite beads at 1200°C for 1 hour resulted in the decomposition of the hydroxyapatite phase and formation of a-TCP. XRD analysis revealed that a-TCP-CeO2-Al2O3 composite beads were achieved. XRD analysis confirmed the formation of a-TCP phase in all composite compositions. SEM investigations of the produced composite beads revealed that bimodal pore size distribution, fine and coarse, was achieved.