On the convergence of an iteration process for nonself totally asymptotically I-quasi-nonexpansive mappings

Birol Gunduz,Hemem Dutta 장전수학회 2017 Proceedings of the Jangjeon mathematical society Vol.20 No.3

In this paper, we first define nonself total asymptotically I-nonexpansive mappings and nonself total asymptotically I-quasi-nonexpansive mappings. Then, we prove weak and strong convergence theorems of a composite iterative process to a common fixed point of nonself total asymptotically quasi-nonexpansive map- pings and nonself total asymptotically I-quasi-nonexpansive mappings, defined on a nonempty closed convex subset of uniformly convex Banach space.

GENERALIZED PELL SEQUENCES RELATED TO THE EXTENDED GENERALIZED HECKE GROUPS ${\bar{H}}$ _3,q AND AN APPLICATION TO THE GROUP ${\bar{H}}$ _3,3

Birol, Furkan,Koruoglu, Ozden,Sahin, Recep,Demir, Bilal The Honam Mathematical Society 2019 호남수학학술지 Vol.41 No.1

We consider the extended generalized Hecke groups ${\bar{H}}_{3,q}$ generated by $X(z)=-(z-1)^{-1}$, $Y(z)=-(z+{\lambda}_q)^{-1}$ with ${\lambda}_q=2\;cos({\frac{\pi}{q}})$ where $q{\geq}3$ an integer. In this work, we study the generalized Pell sequences in ${\bar{H}}_{3,q}$. Also, we show that the entries of the matrix representation of each element in the extended generalized Hecke Group ${\bar{H}}_{3,3}$ can be written by using Pell, Pell-Lucas and modified-Pell numbers.

Solution of the Advection-Diffusion Equation Using the Differential Quadrature Method

Birol Kaya 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.1

Differential Quadrature Method (DQM) to integrate the one-dimensional Advection–diffusion Equation (ADE) is presented. This method was applied to two examples and the results were compared with the performance of the Explicit Finite Difference Method (EFDM) and Implicit Finite Differences Method (IFDM). Based on the comparison with the exact solution, and both the explicit and implicit finite difference solutions, it was concluded that the DQM provides similar results but less grid points; besides the results are converged quickly. A numerical comparison for a case in which the exact solution is known, DQM gives closer results to the exact values than EFDM and IFDM.

Molecular Characterization of Antibiotic Resistant Escherichia coli Strains Isolated from Tap and Spring Waters in a Coastal Region in Turkey

Osman Birol Ozugumus,Elif Celik-Sevim,Sengul Alpay-Karaoglu,Cemal Sandalli,Ali Sevim 한국미생물학회 2007 The journal of microbiology Vol.45 No.5

A hundred and seventeen antibiotic-resistant Escherichia coli strains were isolated from public tap and spring waters which were polluted by fecal coliforms. There were no significant differences between two water sources as to the coliform pollution level (p> 0.05). All E. coli isolates were detected to be resistant to one or more antibiotics tested. Nearly 42% of the isolates showed multiresistant phenotype. Three (2.5%) of these isolates contained class 1 integron. Sequencing analysis of variable regions of the class 1 integrons showed two gene cassette arrays, dfr1-aadA1 and dhfrA17-aadA5. Resistance to ampicillin, tetracycline or trimethoprim-sulfamethoxazole was transferable according to the results of conjugation experiments. The rate of tetracycline resistance was 15%. tet(A)-mediated tetracycline resistance was widespread among tetracycline-resistant E. coli isolates. Genotyping by BOX-polymerase chain reaction (BOX-PCR) showed that some of the strains were epidemiologically related. This is the first report on the prevalence and characterization of class 1 integron-containing E. coli isolates of environmental origin in Turkey.

Class 1 and Class 2 Integrons and Plasmid-Mediated Antibiotic Resistance in Coliforms Isolated from Ten Rivers in Northern Turkey

Osman Birol Ozgumus,Cemal Sandalli,Ali Sevim,Elif Celik-Sevim,Nuket Sivri 한국미생물학회 2009 The journal of microbiology Vol.47 No.1

We aimed to determine the molecular mechanisms of antibiotic resistance in coliforms isolated from ten rivers in northern region of Turkey. A total of 183 isolates were tested for antimicrobial susceptibility by disk diffusion and agar dilution methods. Resistance to ampicillin, streptomycin, trimethoprim, tetracycline, and chloramphenicol was detected in 58%, 51.9%, 24%, 28.4%, and 12.5%, respectively. Twelve (6.5%) phylogenetically distant organisms were detected to harbor self-transmissible plasmids ranging 52 to >147 kb in sizes. Resistances to ampicillin, tetracycline, trimethoprim, streptomycin, and nalidixic acid were commonly transferable traits. Transferable nalidixic acid-resistant strains harbored qnrS gene, which was the first report of plasmid-mediated quinolone resistance in bacteria of environmental origin in Turkey. Fourteen and five coliforms harbored class 1 and class 2 integrons, respectively, and some of them were located on transferable plasmids. Sequence analyses of variable regions of the class 1 and 2 integrons harbored various gene cassettes, dfrA1, dfr2d, dfrA7, dfrA16, dfrA17, aadA1, aadA5, blaOXA-30, and sat1. A gene cassette array, dfrA16 has been demonstrated for the first time in a Citrobacter koseri isolate. Class 1 and class 2-bearing strains were clustered in different groups by BOX-PCR fingerprinting. Rivers in the northern Turkey may act as receptacle for the multi-drug resistant enterobacteria and can serve as reservoirs of the antimicrobial resistance determinants in the environment. The actual risk to public health is the transfer of resistance genes from the environmental bacteria to human pathogens.

Friction Stir Welding of Twin-Roll Cast EN AW 3003 Plates

Yucel Birol,Sefika Kasman 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6

Twin-roll cast EN AW 3003 plates were butt-welded with friction stir welding and their structural features were identified. Sound welds were obtained in twin-roll cast EN AW 3003 plates at tool rotation speeds higher than 500 rpm. The ultimate tensile strength of the welded plates was 134 ± 3 MPa, comparable to the ultimate tensile strength of the original plate, at 146 MPa. The stirring action of the pin fractured the interdendritic network and coarse eutectic cells, replacing the dendritic features of the base plate with a uniform dispersion of very fine intermetallic particles across the stir zone. The thermal and mechanical cycles introduced during FSW relaxed the supersaturation of the cast plate, leading to the precipitation of intermetallic particles. This precipitation activity produced a particle population gradient that peaks inside the stir zone and dictates the etching response across the plate section. The material in direct contact with the rotating pin is severely deformed and is exposed to frictional heating and inevitably undergoes dynamic recrystallization. The very fine grain structure thus obtained suffers abnormal grain growth when annealed at high temperatures due to the effective pinning of the grain boundaries by the fine particles.

Thermotropic liquid crystalline 4-(Nonyloxy) benzoic acid: Phase transition temperatures, thermodynamic characterization, and separation of structural isomers

Isik Birol,Cakar Fatih,Cankurtaran Husnu,Cankurtaran Ozlem 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.11

The retention behavior of various organic probes on the 4-(Nonyloxy) benzoic acid liquid crystal, which is used as a stationary phase, was investigated using the inverse gas chromatography method at infinite dilution. The thermodynamic parameters including the Flory-Huggins parameter, equation-of-state interaction parameter, the mole fraction activity coefficient, the effective exchange energy parameter, and residual thermodynamic parameters were determined in the temperature range of 423.15-433.15 K by using the retention behavior of the probes on the liquid crystal. It was determined from the thermodynamic parameters that all probes were poor solvents for the liquid crystal. Besides, the results of the 4-(Nonyloxy) benzoic acid liquid crystal was compared with a liquid crystal in the literature, and the effect of the number of alkyl groups on the liquid crystals on the Flory-Huggins interaction parameter and isomer separation was evaluated.

CONVERGENCE OF A NEW MULTISTEP ITERATION IN CONVEX CONE METRIC SPACES

Gunduz, Birol Korean Mathematical Society 2017 대한수학회논문집 Vol.32 No.1

In this paper, we propose a new multistep iteration for a finite family of asymptotically quasi-nonexpansive mappings in convex cone metric spaces. Then we show that our iteration converges to a common fixed point of this class of mappings under suitable conditions. Our result generalizes the corresponding result of Lee [5] from the closed convex subset of a convex cone metric space to whole space.

Effect of Cr and Zr on the Grain Structure of Extruded EN AW 6082 Alloy

Yucel Birol 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.4

The effects of Cr and Zr addition on the coarse grain surface layer in EN AW 6082 tube extrusions wereinvestigated. The decoration of the tube surfaces and the weld seams with coarse recrystallized grainsreflects the strain as well as the temperature gradients that predominate across the section of the tubesduring extrusion. The recrystallization resistance provided by Mn does not suffice to avoid the coarse surfacegrains. With structural features that are almost identical to those of the base 6082 alloy, the 6082alloy with 0.06 wt% Zr also fails to offer any improvement. The coarse grain surface layer is much thinnerand recrystallization is entirely avoided across the weld seams upon the addition of 0.15 wt% Cr. Thesuperior recrystallization resistance of the revised alloy is attributed to the increase in the population of theCr-rich Al(Cr,Mn,Fe)Si as well as (Al, Si)3Zr dispersoid particles. It is reasonable to conclude that the coadditionof Zr and Cr has a favourable impact on the resistance to recrystallization of EN AW 6082 alloy.

Adsorptive removal of congo red and methylene blue dyes from aqueous solutions by Rumex obtusifolius roots

Isik Birol 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12

Rumex obtusifolius roots were utilized within the scope of zero waste. Sorption of methylene blue and congo red dyes from wastewater was carried out. First, surface properties were determined using inverse gas chromatography. By this method, it was found that the surface of Rumex obtusifolius roots was acidic (KD/KA=0.13). The point of zero charge value of Rumex obtusifolius roots was determined as 5.62. Based on these results and selectivity studies, suitable dyes were selected for sorption studies. Experimental design was used for the first time to determine the parametric effects and to improve the process for the highest methylene blue and congo red removal. Optimum conditions such as pH (2–12), concentration (10–50 mg/L), adsorbent amount (0.01 g/50 mL–0.30g/50 mL), and contact time (0–210 min) were determined for the adsorption process. The Langmuir-2 model provided the best correlation, and qm values for methylene blue and congo red dyes were determined as 500.00 mg/g and 128.21 mg/g at 298 K. From the kinetic studies, it was found that the sorption process for methylene blue and congo red dyes followed pseudo-second-order kinetics. The effect of NaCl and CaCl2 salts on methylene blue and congo red sorption on Rumex obtusifolius roots was evaluated. The adsorption process was found to be endothermic for methylene blue dye (ΔHo=+19.33kJ/mol) and exothermic for congo red dye (ΔHo=−4.99kJ/mol). The process was found to be spontaneous for both dyes (ΔGo=−28.10 kJ/mol for methylene blue dye and ΔGo=−26.14kJ/mol for congo red dye at 298 K). All findings showed the potential of Rumex obtusifolius roots as a model adsorbent for the removal of various organic pollutants from wastewater.