UPPER BOUND ON THE THIRD HANKEL DETERMINANT FOR FUNCTIONS DEFINED BY RUSCHEWEYH DERIVATIVE OPERATOR

Yavuz, Tugba Korean Mathematical Society 2018 대한수학회논문집 Vol.33 No.2

Let S denote the class of analytic and univalent functions in the open unit disk $D=\{z:{\mid}z{\mid}<1\}$ with the normalization conditions f(0) = 0 and f'(0) = 1. In the present article, an upper bound for third order Hankel determinant $H_3(1)$ is obtained for a certain subclass of univalent functions generated by Ruscheweyh derivative operator.

Electrodeposition, Characterization and Long Term Stability of NiW and NiWZn Coatings on Copper Substrate in Alkaline Solution

Yavuz Sürme,A. Ali Gürten,Kadriye Kayaklrllmaz 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.4

This paper describes the electrodeposition of Ni, NiW and NiWZn coatings onto copper surfaces from electrolyte solutions containing Na3C6H5O7, Na2WO4, NiSO4 and ZnSO4. The electrocatalytic effects of electrodeposited coatings were investigated for hydrogen evolution reactions in 1 M NaOH solution. Surface characterization studies were carried out by energy dispersive X-ray spectroscopy, scanning electron microscopy,atomic force microscopy and cross-section analysis. The effect of operating conditions on the chemical composition,microstructure and electrocatalytic properties of Ni-W coatings was studied. The Zn ions were used to improve the active surface area and catalytic activity of the electrodeposited surface. The electrocatalytic activity of NiW and NiWZn coated electrodes for the hydrogen evolution reaction in alkaline solution was compared with that of an electrodeposited Ni electrode and copper substrate by using cathodic polarization curves and electrochemical impedance spectroscopy techniques over 96 h of electrolysis. The results proved that the NiWZn coated electrode showed better electrocatalytic activity and durability than bare Cu, Ni and NiW coatings.

Effect of Probiotics on the Treatment of Children with Atopic Dermatitis

( Yavuz Yesilova ),( Omer Calka ),( Necmettin Akdeniz ),( Mustafa Berktas ) 대한피부과학회 2012 Annals of Dermatology Vol.24 No.2

Background: Atopic dermatitis, a chronic recurrent disease, is frequently encountered in clinical practice. In the last 30 years, the prevalence of atopic dermatitis has rapidly increased due to industrialization. Therefore, there have been attempts in recent years to find new ways of treating and preventing atopic dermatitis. Objective: In this double-blind, randomized, placebo-controlled study, a combination of Bifidobacterium bifidum, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus salivarius strains were evaluated in the treatment of atopic dermatitis in pediatric patients. Methods: Forty pediatric patients (23 males and 17 females) aged 1∼13 years were enrolled. One eligible individual who was approached declined to participate. The probiotic group was administered a probiotic complex containing B. bifidum, L. acidophilus, L. casei, and L. salivarius for 8 weeks. The placebo group, on the other hand, was administered skim milk powder and dextrose. All of the parameters including serum cytokines, eosinophil cationic protein), SCORing Atopic Dermatitis (SCORAD) index, and total serum immunoglobulin E (IgE) were measured in both the probiotic group and the placebo group at the end of 8 weeks. Results: Probiotic intervention in pediatric atopic dermatitis patients effectively reduced the SCORAD index and serum cytokines interleukin (IL)-5, IL-6, interferon (IFN)-γ, and total serum IgE levels, but did not reduce levels of serum cytokines IL-2, IL-4, IL-10, ECP, or tumor necrosis factor-α (TNF-α) compared to the placebo group. Conclusion: Our study found probiotics to be effective in reducing atopic dermatitis patients` SCORAD index, serum IL-5, IL-6, IFN-γ, and total serum IgE levels but not effective in reducing serum IL-2, IL-4, IL-10, ECP, or TNF-α levels. (Ann Dermatol 24(2) 189∼193, 2012)

NEW CHARACTERIZATION OF THE CLASS OF STARLIKE FUNCTIONS

Yavuz, Emel,Polatoglu, Yasar,Owa, Shigeyoshi Korean Mathematical Society 2008 대한수학회보 Vol.45 No.4

For analytic functions f(z) in the open unit disc $\mathbb{D}$, an operator $N_{\alpha}(f(z))$ relating with starlike functions is introduced. The object of the present paper is to discuss some properties of the operator $N_{\alpha}(f(z))$.

Role of Reinforcement Materials on Mechanical and Tribological Properties of PTFE Composites

Yavuz Kaplan 한국고분자학회 2020 폴리머 Vol.44 No.4

The use of polytetrafluoroethylene (PTFE) in various industrial applications under extreme operating conditions makes it very important to determine the behavior of this material. The mechanical and wear properties of PTFE can be enhanced by adding filler materials. This study focused on both the mechanical and tribological properties of PTFE and its composites with a 25 wt% addition of carbon and glass fiber (GF). Glass transition temperature (Tg), hardness, tensile, and impact tests were carried out to determine the mechanical and physical properties of PTFE. In addition, abrasive wear tests were applied to obtain wear behavior. The tensile strength values of the pure and C/GF-filled PTFE were found as 28, 16.7, and 18.6MPa, respectively. Tensile tests clearly showed that the filler materials led to a reduction of the tensile strength and elongation at break of the PTFE. Impact energy values were similarly decreased by the addition of filler materials. However, the carbon and GF additions significantly increased the abrasive wear resistance and Tg of the PTFE. Consequently, carbon and GF-filled PTFE would be a suitable candidate for use in tribological applications.

Numerical study of ship motions and added resistance in regular incident waves of KVLCC2 model

Yavuz Hakan Ozdemir,Baris Barlas 대한조선학회 2017 International Journal of Naval Architecture and Oc Vol.9 No.2

In this study, the numerical investigation of ship motions and added resistance at constant forward velocity of KVLCC2 model is presented. Finite volume CFD code is used to calculate three dimensional, incompressible, unsteady RANS equations. Numerical computations show that reliable numerical results can be obtained in head waves. In the numerical analyses, body attached mesh method is used to simulate the ship motions. Free surface is simulated by using VOF method. The relationship between the turbulence viscosity and the velocities are obtained through the standard k ε turbulence model. The numerical results are examined in terms of ship resistance, ship motions and added resistance. The validation studies are carried out by comparing the present results obtained for the KVLCC2 hull from the literature. It is shown that, ship resistance, pitch and heave motions in regular head waves can be estimated accurately, although, added resistance can be predicted with some error.

Performance Analysis on Solar Concentrating Thermoelectric Generator Coupled with Heat Sink

Yavuz Köysal 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.2

The usage of thermoelectric generators (TEGs) is rapidly increasing where the waste heat exists. Today, many experiments are being conducted to investigate solar energy systems with waste heat. This work focuses on the performance of an individual TEG via a spot Fresnel lens. Therefore, an experimental system was constructed so that the TEG module could show high performance under the concentrated solar radiation. For this aim, the system was adapted to one-axis sun tracking system for receiving maximum solar irradiation. It was observed that the obtained experimental values of the parameters such as open circuit voltage, hot side temperature and cold side temperature of the TEG module are consistent with the collected solar values. The experimental data was collected at GPS coordinates of 41°14′N and 36°26′E (Samsun, Turkey) on 8th of September, 2017. The maximum open circuit voltage value was obtained as 0.822 V.

Transient response of functionally graded non-uniform cylindrical helical rods

Yavuz C. Cuma,Faruk Firat Calim 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.4

This paper have the objective of investigating forced vibration behaviour of axially functionally graded cylindrical helices with variable cross-section. An algorithm is developed in order to solve corresponding problems. The ordinary differential equations governing the dynamic behaviour of cylindrical helices are determined in Laplace domain by using Timoshenko beam theory. Then transfer matrix method is implemented for the solution, including shear and axial deformation effects. Obtained results are transferred to time domain using Durbin’s modified numerical inverse algorithm for Laplace transform. A benchmark problem has been solved to check the accuracy of developed algorithm then a parametric study is conducted considering the effects of material gradient index ( ), section variation parameter ( ) and number of active turns ( ). Results are compared with solutions attained from ANSYS for verification

Effects of Epinephrine and Cortisol on the Analgesic Activity of Metyrosine in Rats

Yavuz Albayrak,Mustafa Bahadir Saglam,Kadir Yildirim,Saliha Karatay,Beyzagul Polat,Turan Uslu,Fatih Akcay,Halis Suleyman 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.9

Some endogenous hormones (epinephrine and cortisol) can change an individual’s pain threshold. Propranolol is a non-selective β adrenergic receptor blocker which antagonises the antiinflammatory effect of non-steroidal anti-inflammatory drugs via the β1 and β2 adrenergic receptors. The roles of epinephrine and cortisol were investigated in the analgesic activity of metyrosine in rats with reduced epinephrine levels induced by metyrosine. Pain threshold measurement was performed using an analgesimeter with different doses and the single or combined usage of metyrosine, prednisolone, metyrapone and propranolol in rats. Epinephrine and corticosterone levels were measured by high-performance liquid chromatography in metyrosine-administered rats. Metyrosine reduces the epinephrine levels without affecting the corticosterone levels, thereby creating an analgesic effect. It was determined that prednisolone did not have an analgesic effect in rats with normal epinephrine levels, but its analgesic activity increased with a parallel decrease in the epinephrine levels. Similarly, the combined use of prednisolone and metyrosine provided a stronger analgesic effect than that rendered by metyrosine alone. The strongest analgesic effect, however, was observed in the group of rats with the lowest epinephrine level in whom the metyrosine + prednisolone combination was administered. The findings of this study may be useful in severe pain cases in which the available analgesics are unable to relieve the individual’s pain.

Comparison of Intravesical Hyaluronic Acid, Chondroitin Sulfate, and Combination of Hyaluronic Acid-Chondroitin Sulfate Therapies in Animal Model of Interstitial Cystitis

Yavuz Onur Danacioglu,Bulent Erol,Seyma Ozkanli,Asif Yildirim,Ramazan Gokhan Atis,Mesrur Selcuk Silay,Turhan Caskurlu 대한배뇨장애요실금학회 2021 International Neurourology Journal Vol.25 No.1

Purpose: Three intravesical treatment agents were compared in an interstitial cystitis rat model: chondroitin sulfate, hyaluronic acid, and combined hyaluronic acid-chondroitin sulfate. Methods: Thirty-five female rats were divided into 5 groups: control (group I), isotonic (group II), chondroitin sulfate (group III), hyaluronic acid (group IV), and hyaluronic acid-chondroitin sulfate (group V). Chemical cystitis was induced in all experimental groups by intravesical instillation of 1 mL of hydrogen peroxide (H2O2) for 15 minutes via the transurethral route. The treatment was administered every other day for 3 sessions 2 days after inducing chemical cystitis. Groups II, III, IV, and V received 1 mL of 0.9% NaCl, 1 mL of 0.2% sodium chondroitin sulfate, 1 mL of low-molecular-weight hyaluronic acid, and 1 mL of 2% sodium chondroitin sulfate+1.6% sodium hyaluronic acid, respectively. On day 7, the animals were sacrificed and the bladders were removed for histopathological and immunohistochemical assessments. Results: Significant between-group differences were found in vascular congestion (P=0.006). The grade of submucosal edema in groups II and IV was significantly higher than in group I (P=0.006, P=0.006, respectively). In group I, the grade of granulation tissue was lower than the other 4 groups, but no significant difference was found between the remaining groups (P=0.016). Neutrophil cell infiltration was more intense in groups II and IV than in group I (P=0.006, P=0.006, respectively). Significant differences in the leukocyte and mast cell count were detected between groups II and IV (P<0.001, P<0.001, respectively). Abnormal zonula occludens-1 and uroplakin-III immunoreactivity in group II was higher than in groups I, III, or V (P=0.002, P=0.010, respectively). Interleukin-8 expression was lower in group V than in group II (P=0.001). Conclusion: A single treatment of chondroitin sulfate and combined hyaluronic acid-chondroitin sulfate treatment demonstrated efficacy by suppressing inflammation and achieving improvements in the urothelium.