Production and investigation of 3D printer ABS filaments filled with some rare-earth elements for gamma-ray shielding

Gultekin Batuhan,Bulut Fatih,Yildiz Hatice,Us Hakan,Ogul Hasan 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.12

Radiation is the main safety issue for almost all nuclear applications, which must be controlled to protect living organisms and the surrounding materials. In this context, radiation shielding materials have been investigated and used in nuclear technologies. The choice of materials depends on the radiation usage area, type, and energy. Polymer materials are preferred in radiation shielding applications due to their superior characteristics such as chemical inertness, resistivity, low weight, flexibility, strength, and low cost. In the presented work, ABS polymer material, which is possibly the most commonly used material in 3D printers, is mixed with Gd2O3 and Er2O3 nanoparticles. ABS filaments containing these rare-earth elements are then produced using a filament extruder. These produced filaments are used in a 3D printer to create shielding samples. Following the production of shielding samples, SEM, EDS, and gamma-ray shielding analyses (including experiments, WinXCOM, GEANT4, and FLUKA) are performed. The results show that 3D printing technology offers significant enhancements in creating homogeneous and well-structured materials that can be effectively used in gamma-ray shielding applications.

Prediction of behavior of fresh concrete exposed to vibration using artificial neural networks and regression model

Gultekin Aktas,Mehmet Sirac Ozerdem 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.4

This paper aims to develop models to accurately predict the behavior of fresh concrete exposed to vibration using artificial neural networks (ANNs) model and regression model (RM). For this purpose, behavior of a full scale precast concrete mold was investigated experimentally and numerically. Experiment was performed under vibration with the use of a computer-based data acquisition system. Transducers were used to measure time-dependent lateral displacements at some points on mold while both mold is empty and full of fresh concrete. Modeling of empty and full mold was made using both ANNs and RM. For the modeling of ANNs: Experimental data were divided randomly into two parts. One of them was used for training of the ANNs and the remaining part was used for testing the ANNs. For the modeling of RM: Sinusoidal regression model equation was determined and the predicted data was compared with measured data. Finally, both models were compared with each other. The comparisons of both models show that the measured and testing results are compatible. Regression analysis is a traditional method that can be used for modeling with simple methods. However, this study also showed that ANN modeling can be used as an alternative method for behavior of fresh concrete exposed to vibration in precast concrete structures.

Investigation of fresh concrete behavior under vibration using mass-spring model

Gultekin Aktas 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.3

This paper deals with the behavior of fresh concrete that is under vibration using mass-spring model (MSM). To this end, behaviors of two different full scale precast concrete molds were investigated experimentally and theoretically. Experiments were performed under vibration with the use of a computerbased data acquisition system. Transducers were used to measure time-dependent lateral displacements at some points on mold while mold is empty and full of fresh concrete. Analytical modeling of molds used in experiments were prepared by three dimensional finite element method (3D FEM) using software. Modeling of full mold, using MSM, was made to solve the problem of dynamic interaction between fresh concrete and mold. Numerical displacement histories obtained from time history analysis were compared with experimental results. The comparisons show that the measured and computed results are compatible.

A multicultural education approach to Turkish picture books written for Syrian refugee children

Gultekin Mehmet 한국다문화교육학회 2022 Multicultural Education Review Vol.14 No.2

Syrian refugees worldwide experience many difficulties, including integrating into the host country. Turkey host most of the Syrian refugees, but limited studies examined Syrian refugees’ transnational experiences in children’s literature. In this study, I have examined the picture books written for Syrian refugee children published in Turkey through a multicultural education framework to highlight how microculture and macroculture relate to each other. The books are produced by Promoting the Integration of Syrian Children into the Turkish Education System (PIKTES), which is supported by European Union (EU). I utilized content analysis and analyzed each book with the relationship between microculture and macroculture. I represented findings under three categories: shared cultural values between microculture and macroculture, decontextualization of Syrian refugee identity, and monistic representation of the social class. I suggested the need for quality picture books for multicultural education and authentic textual spaces for a smooth integration of Syrian refugee children.

Lack of Influence of the ACE1 Gene I/D Polymorphism on the Formation and Growth of Benign Uterine Leiomyoma in Turkish Patients

Gultekin, Guldal Inal,Yilmaz, Seda Gulec,Kahraman, Ozlem Timirci,Atasoy, Hande,Dalan, A. Burak,Attar, Rukset,Buyukoren, Ahmet,Ucunoglu, Nazli,Isbir, Turgay Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.3

Uterine leiomyomas (ULM), are benign tumors of the smooth muscle cells of the myometrium. They represent a common health problem and are estimated to be present in 30-70% of clinically reproductive women. Abnormal angiogenesis and vascular-related growth factors have been suggested to be associated with ULM growth. The angiotensin-I converting enzyme (ACE) is related with several tumors. The aim of this study was to identify possible correlation between ULM and the ACE I/D polymorphism, to evaluate whether the ACE I/D polymorphism could be a marker for early diagnosis and prognosis. ACE I/D was amplified with specific primer sets recognizing genomic DNA from ULM (n=72) and control (n=83) volunteers and amplicons were separated on agarose gels. The observed genotype frequencies were in agreement with Hardy-Weinberg equilibrium ($x^2=2.162$, p=0.339). There was no association between allele frequencies and study groups ($x^2=0.623$; p=0.430 for ACE I allele, $x^2=0.995$; p=0.339 for ACE D allele). In addition, there were no significant differences between ACE I/D polymorphism genotype frequencies and ULM range in size and number ($X^2=1.760;$ p=0.415 for fibroid size, $X^2=0.342;$ p=0.843 for fibroid number). We conclude that the ACE gene I/D polymorphism is not related with the size or number of ULM fibroids in Turkish women. Thus it cannot be regarded as an early diagnostic parameter nor as a risk estimate for ULM predisposition.

Metaplastic Breast Carcinoma: a Heterogeneous Disease

Gultekin, Melis,Eren, Gulnihan,Babacan, Taner,Yildiz, Ferah,Altundag, Kadri,Guler, Nilufer,Ozisik, Yavuz,Yazici, Gozde,Hurmuz, Pervin,Gurkaynak, Murat Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.6

The aim of this study is to evaluate clinicopathologic characteristics and the multi-disciplinary treatment results of metaplastic breast cancer (MBC) patients treated in a single institute. Seventeen female patients with MBC treated in our department between June 2000 and January 2012 were identified and retrospectively evaluated. The median age at diagnosis was 46 years (range, 26-66 years). The median tumor size at diagnosis was 3.5 cm (range 1.5-12 cm). Six (35%) patients underwent breast conservation surgery and 11 (65%) mastectomy. Axillary lymph node metastasis was found in 6 (35%) patients. Twelve (71%) had triple negative tumors. Postoperative RT and systemic adjuvant treatment was given to all patients accordingly to stage and biological characteristics. Median follow-up time was 27 months (range, 12-151 months). At the time of this analysis, 14 (82%) patients were alive with no evidence of disease, and 1 (6%) was alive with disease. The 3-year OS was 91% and 5-year 80%, and DFS rates were 76% and 76%, respectively. Despite the young age of our patients with mostly high grade tumors, larger tumor size and higher rates of lymph node metastasis, the survival outcomes in our study are favorable in comparison with previously reported series.

Displacement prediction of precast concrete under vibration using artificial neural networks

Gultekin Aktas,Mehmet Sirac Ozerdem 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.4

This paper intends to progress models to accurately estimate the behavior of fresh concrete under vibration using artificial neural networks (ANNs). To this end, behavior of a full scale precast concrete mold was investigated numerically. Experimental study was carried out under vibration with the use of a computer-based data acquisition system. In this study measurements were taken at three points using two vibrators. Transducers were used to measure time-dependent lateral displacements at these points on mold while both mold is empty and full of fresh concrete. Modeling of empty and full mold was made using ANNs. Benefiting ANNs used in this study for modeling fresh concrete, mold design can be performed. For the modeling of ANNs: Experimental data were divided randomly into two parts such as training set and testing set. Training set was used for ANN’s learning stage. And the remaining part was used for testing the ANNs. Finally, ANN modeling was compared with measured data. The comparisons show that the experimental data and ANN results are compatible.

Survival of gynecological cancers in Turkey: where are we at?

Murat Gultekin,Selin Dundar,Irem Kucukyildiz,Mujdegul Zayifoglu Karaca,Guledal Boztas,Semra Hatice Turan,Ezgi Hacikamiloglu,Bekir Keskinkilic 대한부인종양학회 2017 Journal of Gynecologic Oncology Vol.28 No.6

Objective: To investigate the 5-year relative survival rates in gynecological cancers diagnosed and treated in Turkey by year 2009 and to compare the results with developed countries. Methods: Data of patients diagnosed for ovarian, corpus uteri or cervix uteri cancer at year 2009 are collected from 9 national cancer registry centers. Date of deaths are retracted from governmental Identity Information Sharing System (KPS). In order to calculate relative survival rates, national general population mortality tables are obtained from Turkish Statistical Institute (TurkStat). Hakulinen method is used for computing curves by R program. Data for European, Asian and some developed countries were obtained from official web pages. Results: A total of 1,553 patients are evaluated. Among these, 713 (45.9%) are corpus uteri cancers, while remaining 489 (31.5%) are ovarian and 351 (22.6%) are cervix uteri. Five-year overall relative survival rates are 85%, 50%, and 62% for corpus uteri, ovarian, and cervix uteri, respectively. These figures are between 73%–87% for corpus uteri, 31%–62% for ovarian and 61%–80% for cervix uteri in developed countries. Stage is the most important factor for survival in all cancers. Five-year relative survival rates in corpus uteri cancers are 92%, 66%, and 38% for localized, regional, and distant metastatic disease, respectively. These figures are 77%, 57%, and 29% for ovarian; 80%, 50%, and 22% for cervix uteri. Conclusion: This is the first report from Turkey giving national overall relative survival for gynecological cancers from a population based cancer registry system.

An experimental investigation of interceptors for a high speed hull

Ahmet Gultekin Avci,Baris Barlas 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

Nowadays interceptors have been widely used in a vast range of high-speed crafts. In this study, the results of interceptor adeptness experiments made in Istanbul Technical University's Towing Tank are unveiled. The model was tested through three transverse locations of interceptors with six different deployment depths. For three locations, the interceptor was positioned transverse on the aft; close to chine, in the middle and close to the keel. The fourth interceptor was a full length of 13.00% LWL. The results show a significant drag reduction in benefits of 1.50%e11.30% for Fn 0.58e1.19 and the trim reduction was observed in between 1.60 and 4.70. Besides, one of the most significant conclusions indicates that the effect of the interceptor decreases from keel to chine for the same blade deployment heights so the blades should be controlled separately at least in three parts from keel to chine area, if operable.

An experimental investigation of interceptors for a high speed hull

Avci, Ahmet Gultekin,Barlas, Baris The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

Nowadays interceptors have been widely used in a vast range of high-speed crafts. In this study, the results of interceptor adeptness experiments made in Istanbul Technical University's Towing Tank are unveiled. The model was tested through three transverse locations of interceptors with six different deployment depths. For three locations, the interceptor was positioned transverse on the aft; close to chine, in the middle and close to the keel. The fourth interceptor was a full length of 13.00% LWL. The results show a significant drag reduction in benefits of 1.50%-11.30% for Fn 0.58-1.19 and the trim reduction was observed in between 1.60 and $4.70^{\circ}$. Besides, one of the most significant conclusions indicates that the effect of the interceptor decreases from keel to chine for the same blade deployment heights so the blades should be controlled separately at least in three parts from keel to chine area, if operable.