Analysis of the mechano-bactericidal effects of nanopatterned surfaces on implant-derived bacteria using the FEM

Ecren Uzun Yaylaci,Mehmet Emin Ozdemir,Yilmaz Guvercin,Sevval Ozturk,Murat Yaylaci Techno-Press 2023 Advances in nano research Vol.15 No.6

The killing of bacteria by mechanical forces on nanopatterned surfaces has been defined as a mechano-bactericidal effect. Inspired by nature, this method is a new-generation technology that does not cause toxic effects and antibiotic resistance. This study aimed to simulate the mechano-bactericidal effect of nanopatterned surfaces' geometric parameters and material properties against three implant-derived bacterial species. Here, in silico models were developed to explain the interactions between the bacterial cell and the nanopatterned surface. Numerical solutions were performed based on the finite element method. Elastic and creep deformation models of bacterial cells were created. Maximum deformation, maximum stress, maximum strain, as well as mortality of the cells were calculated. The results showed that increasing the peak sharpness and decreasing the width of the nanopatterns increased the maximum deformation, stress, and strain in the walls of the three bacterial cells. The increase in spacing between nanopatterns increased the maximum deformation, stress, and strain in E. coli and P. aeruginosa cell walls it decreased in S. aureus. The decrease in width with the increase in sharpness and spacing increased the mortality of E. coli and P. aeruginosa cells, the same values did not cause mortality in S. aureus cells. In addition, it was determined that using different materials for nanopatterns did not cause a significant change in stress, strain, and deformation. This study will accelerate and promote the production of more efficient mechano-bactericidal implant surfaces by modeling the geometric structures and material properties of nanopatterned surfaces together.

Analyzing the mechano-bactericidal effect of nano-patterned surfaces by finite element method and verification with artificial neural networks

Ecren Uzun Yaylaci,Murat Yaylaci,Mehmet Emin Ozdemir,Merve Terzi,Sevval Ozturk Techno-Press 2023 Advances in nano research Vol.15 No.2

The study investigated the effect of geometric structures of nano-patterned surfaces, such as peak sharpness, height, width, aspect ratio, and spacing, on mechano-bactericidal properties. Here, in silico models were developed to explain surface interactions with Escherichia coli. Numerical solutions were performed based on the finite element method and verified by the artificial neural network method. An E. coli cell adhered to the nano surface formed elastic and creep deformation models, and the cells' maximum deformation, maximum stress, and maximum strain were calculated. The results determined that the increase in peak sharpness, aspect ratio, and spacing values increased the maximum deformation, maximum stress, and maximum strain on E. coli cell. In addition, the results showed that FEM and ANN methods were in good agreement with each other. This study proved that the geometrical structures of nano-patterned surfaces have an important role in the mechano-bactericidal effect.

Lack of Variation in Inflammatory Hematological Parameters between Benign Nodular Goiter and Papillary Thyroid Cancer

Yaylaci, Selcuk,Tosun, Onder,Sahin, Orhan,Genc, Ahmet Bilal,Aydin, Ercan,Demiral, Gokhan,Karahalil, Fatma,Olt, Serdar,Ergenc, Hasan,Varim, Ceyhun Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4

Background: Inflammatory hematological parameters like the neutrophil/lymphocyte (N/L) ratio have been investigated in many cancer types and significant relationships found with prognosis, for example. The aim of this present study was to investigate the impact of hematological parameters notably on N/L ratio and mean platelet volume (MPV) in papillary thyroid cancer cases. Materials and Methods: A total of 79 patients who underwent a thyroidectomy operation in Findikli, Goiter Research and Treatment Center during 2011-2015 period were enrolled in the study, 41 with papillary thyroid cancer and 38 with benign goiter confirmed by pathological examination. We collected clinical and laboratory data for the patients from hospital records retrospectively. Blood samples taken at admission were assessed for parameters compared between the groups. Results: No significant differences between papillary thyroid cancer and benign goiter groups were apparent in terms of age, the N/L ratio, MPV, white blood cell count (WBC), red blood cell count (RBC), hemoglobin, hematocrit, platelet, neutrophil, lymphocyte, red blood cell distribution width (RDW) and platelet crit (PCT) levels (p>0.05). Only the level of platelet distribution width (PDW) significantly differed, being lower in the papillary cancer group (p<0.05). Conclusions: No significant relationship between papillary thyroid cancer and inflammatory hematological parameters including in particular the N/L ratio and MPV. The relevance of the PDW values remains unclear.

Simulate of edge and an internal crack problem and estimation of stress intensity factor through finite element method

Yaylaci, Murat Techno-Press 2022 Advances in nano research Vol.12 No.4

In this study, the elastic plane problem of a layered composite containing an internal or edge crack perpendicular to its boundaries in its lower layer is examined using numerical analysis. The layered composite consists of two elastic layers having different elastic constants and heights. Two bonded layers rest on a homogeneous elastic half plane and are pressed by a rigid cylindrical stamp. In this context, the Finite Element Method (FEM) based software called ANSYS is used for numerical solutions. The problem is solved under the assumptions that the contacts are frictionless, and the effect of gravity force is neglected. A comparison is made with analytical results in the literature to verify the model created and the results obtained. It was found that the results obtained from analytical formulation were in perfect agreements with the FEM study. The numerical results for the stress-intensity factor (SIF) are obtained for various dimensionless quantities related to the geometric and material parameters. Consequently, the effects of these parameters on the stress-intensity factor are discussed. If the FEM analysis is used correctly, it can be an efficient alternative method to the analytical solutions that need time.

Evaluation of the radiopacity of restorative materials with different structures and thicknesses using a digital radiography system

Yaylaci, Ayla,Karaarslan, Emine Sirin,Hatırli, Huseyin Korean Academy of Oral and Maxillofacial Radiology 2021 Imaging Science in Dentistry Vol.51 No.-

Purpose: The aim of this study was to evaluate the radiopacities of various types of restorative materials with different thicknesses compared with enamel, dentin, and aluminum. Materials and Methods: Four bulk-fill resins, 2 hybrid ceramics, 2 micro-hybrid resin composites, 6 glass ionomer-based materials, 2 zinc phosphate cements, and an amalgam were used in the study. Twelve disk-shaped specimens were prepared from each of 17 restorative materials with thicknesses of 1 mm, 2 mm, and 4 mm (n=4). All the restorative material specimens with the same thickness, an aluminum (Al) step wedge, and enamel and dentin specimens were positioned on a phosphor storage plate and exposed using a dental X-ray unit. The mean gray values were measured on digital images and converted to equivalent Al thicknesses. Statistical analyses were performed using 2-way analysis of variance and the Bonferroni post hoc test(P<0.05). Results: Radiopacity was significantly affected by both the thickness and the material type (P<0.05). GCP Glass Fill had the lowest radiopacity value for samples of 1 mm thickness, while Vita Enamic had the lowest radiopacity value for 2-mm-thick and 4-mm-thick samples. The materials with the highest radiopacity values after the amalgam were zinc phosphate cements. Conclusion: Significant differences were observed in the radiopacities of restorative materials with different thicknesses. Radiopacity was affected by both the material type and thickness.

The receding contact problem of two elastic layers supported by two elastic quarter planes

Yaylaci, Murat,Birinci, Ahmet Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.2

The receding contact problem for two elastic layers whose elastic constants and heights are different supported by two elastic quarter planes is considered. The lower layer is supported by two elastic quarter planes and the upper elastic layer is subjected to symmetrical distributed load whose heights are 2a on its top surface. It is assumed that the contact between all surfaces is frictionless and the effect of gravity force is neglected. The problem is formulated and solved by using Theory of Elasticity and Integral Transform Technique. The problem is reduced to a system of singular integral equations in which contact pressures are the unknown functions by using integral transform technique and boundary conditions of the problem. Stresses and displacements are expressed depending on the contact pressures using Fourier and Mellin formula technique. The singular integral equation is solved numerically by using Gauss-Jacobi integration formulation. Numerical results are obtained for various dimensionless quantities for the contact pressures and the contact areas are presented in graphics and tables.

What Would Korea-US Free Trade Agreement Bring?

Ozlem Yaylaci,Serge Shikher 한국국제경제학회 2014 International Economic Journal Vol.28 No.1

This paper uses a computable model of trade to forecast the effects of the US–Korea free trade agreement on the manufacturing sector. The model uses the Eaton–Kortum methodology to explain intra-industry trade instead of the usual Armington assumption. It is parameterized using 2005 data for 15 industries and 53 countries. The results show that implementing KORUS would increase the US manufacturing exports to Korea by 56.9% and Korean manufacturing exports to the US by 18.9%. It would also increase manufacturing employment by 26,500 jobs in Korea and 34,200 jobs in the US. In addition, KORUS would lead to significant changes in the patterns of trade and production. The US and Korea would increase their specialization in the industries where they have strong technological comparative advantages. Finally, KORUS would increase welfare in both countries, but only modestly: by 0.27% in Korea and 0.013% in the US.

Analytical and finite element solution of a receding contact problem

Adiyaman, Gokhan,Yaylaci, Murat,Birinci, Ahmet Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.1

In this paper, a receding contact problem for an elastic layer resting on two quarter planes is considered. The layer is pressed by a stamp and distributed loads. It is assumed that the contact surfaces are frictionless and only compressive traction can be transmitted through the contact surfaces. In addition the effect of body forces are neglected. Firstly, the problem is solved analytically based on theory of elasticity. In this solution, the problem is reduced into a system of singular integral equations in which contact areas and contact stresses are unknowns using boundary conditions and integral transform techniques. This system is solved numerically using Gauss-Jacobi integral formulation. Secondly, two dimensional finite element analysis of the problem is carried out using ANSYS. The dimensionless quantities for the contact areas and the contact pressures are calculated under various distributed load conditions using both solutions. It is concluded that the position and the magnitude of the distributed load have an important role on the contact area and contact pressure distribution between layer and quarter plane contact surface. The analytic results are verified by comparison with finite element results.

Analytical solution of a contact problem and comparison with the results from FEM

Oner, Erdal,Yaylaci, Murat,Birinci, Ahmet Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.4

This paper presents a comparative study of analytical method and finite element method (FEM) for analysis of a continuous contact problem. The problem consists of two elastic layers loaded by means of a rigid circular punch and resting on semi-infinite plane. It is assumed that all surfaces are frictionless and only compressive normal tractions can be transmitted through the contact areas. Firstly, analytical solution of the problem is obtained by using theory of elasticity and integral transform techniques. Then, finite element model of the problem is constituted using ANSYS software and the two dimensional analysis of the problem is carried out. The contact stresses under rigid circular punch, the contact areas, normal stresses along the axis of symmetry are obtained for both solutions. The results show that contact stresses and the normal stresses obtained from finite element method (FEM) provide boundary conditions of the problem as well as analytical results. Also, the contact areas obtained from finite element method are very close to results obtained from analytical method; disagree by 0.03-1.61%. Finally, it can be said that there is a good agreement between two methods.