An experimental investigation of the effects of chronic stress on bone-to-implant contact

Serkan Dundar,Alihan Bozoglan,Ferhan Yaman,Mustafa Kirtay,Ozgur Bulmus,Hacer Sahin Aydinyurt,Murat Yavuz Solmaz,Cenk Yanen 대한구강악안면외과학회 2019 대한구강악안면외과학회지 Vol.45 No.2

Objectives: This study aimed to investigate the effects of chronic restraint stress on the osseointegration of titanium implants. Materials and Methods: Twenty adult male Wistar albino rats were used in the study. After surgical insertion of titanium implants into the metaphyseal part of the tibial bone, rats were randomly divided into two groups: a control group (CNT group) and an experimental restraint stress group (RS group). In the CNT group, titanium implants were inserted surgically, and rats received no further treatment during the 47-day experimental period. In the RS group, restraint stress was applied for 3 hours per day for 45 days, beginning 2 days after implant surgery. Weight of the rats was measured prior to surgery and at the end of the study to analyze the effects of stress. At the end of the experimental period, rats were euthanized, and implants and surrounding bone tissues were used for undecalcified histological analysis. Serum cortisol levels were assessed in cardiac blood samples from the rats following centrifugation. Results: Average weight of rats in the RS group was lower than that of rats in the CNT group after the experimental protocol had been completed (P<0.05). Further, serum cortisol levels were higher in the RS group than in the CNT group (P<0.05). There were no significant differences in boneimplant connection levels between the two groups (P>0.05). Conclusion: The data analyzed in this study suggest that chronic restraint stress did not adversely affect rats during a 45-day osseointegration period.

Test and analysis of concrete-filled double steel and double skin tubular columns having outer stainless steel tube

Serkan Tokgoz,Sedat Karaahmetli,Cengiz Dundar 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.1

This paper presents experimental and analytical studies of eccentrically loaded concrete-filled double steel (CFDST) and concrete-filled double skin tube (DCFST) columns having outer stainless steel tube. Eighteen CFDST and DCFST column specimens were manufactured and tested to examine the strength and load-deflection responses. In the study, the main parameters were concrete strength, load eccentricity, cross section and slenderness. The strengths, load-deflection diagrams and failure patterns of the columns were observed. In addition, the tested CFDST and DCFST columns were analyzed to attain the capacity and load versus lateral deflection responses. The obtained theoretical results were compared with the test results. A parametric study was also performed to research the effects of the ratio of eccentricity (e/Ho) slenderness ratio (L/r), Ho/to ratio, Hi/ti ratio and the concrete compressive strength on the behavior of columns. In this work, the obtained results indicated that the ductility and capacity of columns were affected by cross section, concrete strength, steel strength, loading eccentricity and slenderness.

Strength of biaxially loaded high strength reinforced concrete columns

Dundar, Cengiz,Tokgoz, Serkan Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.5

An experimental research was conducted to investigate the strength of biaxially loaded short and slender reinforced concrete columns with high strength concrete. In the study, square and L-shaped section reinforced concrete columns were constructed and tested to obtain the load-deformation behaviour and strength of columns. The test results of column specimens were analysed with a theoretical method based on the fiber element technique. The theoretical ultimate strength capacities and the test results of column specimens have been compared and discussed in the paper. Besides this, observed failure mode and experimental and theoretical load-lateral deflection behaviour of the column specimens are presented.

Experimental tests on biaxially loaded concrete-encased composite columns

Serkan Tokgoz,Cengiz Dundar 국제구조공학회 2008 Steel and Composite Structures, An International J Vol.8 No.5

This paper reports an experimental investigation of the behaviour of concrete-encased composite columns subjected to short-term axial load and biaxial bending. In the study, six square and four L-shaped cross section of both short and slender composite column specimens were constructed and tested to examine the load-deflection behaviour and to obtain load carrying capacities. The main variables in the tests were considered as eccentricity of applied axial load, concrete compressive strength, cross section, and slenderness effect. A theoretical procedure considering the nonlinear behaviour of the materials is proposed for determination of the behaviour of eccentrically loaded short and slender composite columns. Two approaches are taken into account to describe the flexural rigidity (EI) used in the analysis of slender composite columns. Observed failure mode and experimental and theoretical load-deflection behaviour of the specimens are presented in the paper. The composite column specimens and also some composite columns available in the literature have been analysed and found to be in good agreement with the test results.

Strength of biaxially loaded high strength reinforced concrete columns

Cengiz Dundar,Serkan Tokgoz 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.5

An experimental research was conducted to investigate the strength of biaxially loaded short and slender reinforced concrete columns with high strength concrete. In the study, square and L-shaped section reinforced concrete columns were constructed and tested to obtain the load-deformation behaviour and strength of columns. The test results of column specimens were analysed with a theoretical method based on the fiber element technique. The theoretical ultimate strength capacities and the test results of column specimens have been compared and discussed in the paper. Besides this, observed failure mode and experimental and theoretical load-lateral deflection behaviour of the column specimens are presented.

A study on load-deflection behavior of two-span continuous concrete beams reinforced with GFRP and steel bars

Ismail Unsal,Serkan Tokgoz,Ismail H. Cagatay,Cengiz Dundar 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.5

Continuous concrete beams are commonly used as structural members in the reinforced concrete constructions. The use of fiber reinforced polymer (FRP) bars provide attractive solutions for these structures particularly for gaining corrosion resistance. This paper presents experimental results of eight two-span continuous concrete beams; two of them reinforced with pure glass fiber reinforced polymer (GFRP) bars and six of them reinforced with combinations of GFRP and steel bars. The continuous beams were tested under monotonically applied loading condition. The experimental load-deflection behavior and failure mode of the continuous beams were examined. In addition, the continuous beams were analyzed with a numerical method to predict the load-deflection curves and to compare them with the experimental results. Results show that there is a good agreement between the experimental and the theoretical load-deflection curves of continuous beams reinforced with pure GFRP bars and combinations of GFRP and steel bars.

A study on load-deflection behavior of two-span continuous concrete beams reinforced with GFRP and steel bars

Unsal, Ismail,Tokgoz, Serkan,Cagatay, Ismail H.,Dundar, Cengiz Techno-Press 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.5

Continuous concrete beams are commonly used as structural members in the reinforced concrete constructions. The use of fiber reinforced polymer (FRP) bars provide attractive solutions for these structures particularly for gaining corrosion resistance. This paper presents experimental results of eight two-span continuous concrete beams; two of them reinforced with pure glass fiber reinforced polymer (GFRP) bars and six of them reinforced with combinations of GFRP and steel bars. The continuous beams were tested under monotonically applied loading condition. The experimental load-deflection behavior and failure mode of the continuous beams were examined. In addition, the continuous beams were analyzed with a numerical method to predict the load-deflection curves and to compare them with the experimental results. Results show that there is a good agreement between the experimental and the theoretical load-deflection curves of continuous beams reinforced with pure GFRP bars and combinations of GFRP and steel bars.

Metastatic Melanoma of the Common Bile Duct Presented with Dyspepsia

Omer Faruk Cetiner,Huseyin Emre Dundar,Sinem Kantarcioglu-Coskun,Serkan Torun,Salih Tokmak 대한소화기학회 2024 대한소화기학회지 Vol.83 No.4

Malignant melanoma (MM) is an aggressive tumor that can metastasize to any organ, but biliary tract metastasis is scarce. We describe a very rare case of MM metastasis to the common bile duct (CBD), presented with only dyspeptic symptoms. The patient had mildly elevated alkaline phosphatase and gamma-glutamyl transferase levels. Magnetic resonance cholangiopancreatography demonstrated a dilated common bile duct with a distal stricture. The MM diagnosis was established with the ampulla of Vater biopsy specimens obtained by endoscopic retrograde cholangiopancreatography (ERCP), and the patient’s symptoms were resolved after biliary stenting. Both primary CBD cancer and other cancer types like MM that metastasize to CBD can cause obstruction and can be manifested only by dyspeptic symptoms. MM metastasis to CBD can cause obstruction manifested only by dyspeptic symptoms without obstructive jaundice. ERCP can be employed as a promising option for treatment and diagnosis. New-onset dyspeptic symptoms in patients with a history of MM should be investigated thoroughly, especially in the context of biliary metastasis.