Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

Erdemir, Ugur,Sancakli, Hande Sar,Sancakli, Erkan,Eren, Meltem Mert,Ozel, Sevda,Yucel, Taner,Yildiz, Esra The Korean Academy of Prosthodonitics 2014 The Journal of Advanced Prosthodontics Vol.6 No.6

PURPOSE. The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS. A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of $6mm{\times}4mm$ and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with $30{\mu}m$ silica oxide particles ($Cojet^{TM}$ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at ${\alpha}=.05$. RESULTS. Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION. Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.

An examination of Turkish and Chinese equity-related barriers to higher education admissions from the capabilities perspective

Burcu Erdemir,Wu Qiuxiang 서울대학교 교육연구소 2023 Asia Pacific Education Review Vol.24 No.1

Despite the potential of tertiary education to generate higher incomes and close the poverty gap within and between countries, it is still a challenge for many countries to ensure equity and quality in their higher education admissions. Compared to the more privileged, students from marginalized backgrounds face inequitable inputs that restrict their academic and personal growth. This comparative analysis used a capabilities approach-based model to examine the personal, discriminatory, institutional, and geographical barriers many students face in the higher education admission processes in Turkey and China. As long as student stratification persists, equity in education cannot be attained; therefore, several gender equality, equity, diversity, and quality-based policy alternatives are presented that focused on grading systems, curriculum and instruction, and quota system changes. Further recommendations are also given for the development of courses and regional development programmes that can assist disadvantaged students convert functionings into capabilities from an early age.

Primary school teachers' levels of self-efficacy according to various settlement areas

Naki Erdemir 서울대학교 교육연구소 2011 Asia Pacific Education Review Vol.12 No.2

The purpose of this study was to determine how elementary teachers use computers, the Internet, and educational technology in the educational process. The purpose was also to gain information regarding the teachers' possession of technological devices and their levels of self-efficacy in using them among the different types of settlement areas. The study was carried out with 300 elementary-level teachers. The Technology Usability Self-Efficacy Instrument (TUSEI) and a semi-structured interview form were the instruments used in the study. Statistically significant differences were found in the self-efficacy of teachers using computers, the Internet, and other technological devices according to different settlement areas in the responses given by the teachers within the framework of the scale. It was understood that teachers were able to search information on subjects of their choice by using search engines on the Internet, but they could not use these tools efficiently for educational purposes. Teachers' self-efficacies were also found to be inefficient in the ability to use writing and graphic programs in the computer environment.

SUPERLUBRICITY IN CARBON FILMS

Ali ERDEMIR 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10

This paper describes a new carbon film that afford superlubricity (i.e, friction coefficients of 0.001-0.005) and superlow wear rates (i.e., 10?¹¹ -10?¹? ㎣/N.m) to sliding metallic and ceramic surfaces, when tested in inert test environments. The wear life of these films are-more than 1000 ㎞ even under very high contact pressures (i.e., 1-3 ㎬) and at a wide range of sliding velocities (i.e., 0.1 to 2 ㎧). They are produced in a plasma enhanced chemical vapor deposition system at room temperature using highly hydrogenated gas discharge plasmas. Extensive research has shown that films grown in highly hydrogenated gas discharge plasmas (i.e., hydrogen-to-carbon ratio of 6 and above) provide superlow friction and wear coefficients. In full paper, specific conditions under which superlubricity can be achieved in carbon films will be discussed and a mechanistic model will be proposed to explain the superlubricity of new carbon films.

Long-term results of radiofrequency and microwave ablation of colorectal cancer liver metastasis

Ahmet Gürkan Erdemir,Sevilay Karahan,Emre Ünal,Türkmen Turan Çiftçi,Devrim Akıncı,Şuayib Yalçın,Okan Akhan 소화기인터벤션의학회 2023 International journal of gastrointestinal interven Vol.12 No.3

Background: Radiofrequency ablation (RFA) or microwave ablation (MWA) is effective for colorectal cancer liver metastases. We aimed to investigate the impact of different variables on survival. Methods: Sixty-four patients (142 lesions) who underwent thermoablation between January 2007 and January 2019 were retrospectively analyzed. The overall survival (OS) and liver progression-free survival (Li-PFS) were compared using Kaplan-Meier analysis. Univariable and multivariable Cox-regression were done to identify prognostic factors. Results: No significant difference was found between median OS (59.39 months) and Li-PFS (41.22 months) of patients who received MWA (n = 33); and median OS (61.00 months) and Li-PFS (53.43 months) of patients who received RFA (n = 31) (OS: P = 0.697; Li-PFS: P = 0.122). The median OS and Li-PFS were significantly decreased with lung metastases and K-ras mutations (P < 0.001). There was no correlation between prior systemic chemotherapy (n = 25) and both outcome parameters (OS: P = 0.613; Li-PFS: P = 0.665). No significant difference was observed in patients with lesions less than 30 mm diameter (n = 44) whether they received prior systemic chemotherapy (n = 17) or not (n = 27) (OS: P = 0.27; Li-PFS: P = 0.42). Similarly, in patients with a lesion of 3–5 cm diameter (n = 20; eight of them had prior chemotherapy), there was no correlation for both outcomes (OS: P = 0.069; Li-PFS: P = 0.71). The most important prognostic factor was concomitant lung metastases (hazard ratio = 3.689, P = 0.002). Conclusion: Concomitant lung metastasis and mutant K-ras were associated with shorter survival. Survival did not differ significantly regarding thermoablation technique or prior systemic chemotherapy. However, in the patient group with lung metastases, curative treatments had better survival than patients who received chemotherapy only. Additional therapeutic options should be considered in patients with concomitant lung metastasis.

Changes in the Physico-chemical and Microbial Quality during the Production of Pastırma Cured with Different Levels of Sodium Nitrite

Aksu, Muhammet Irfan,Erdemir, Ebru,Cakici, Neslihan Korean Society for Food Science of Animal Resource 2016 한국축산식품학회지 Vol.36 No.5

Pastırma, a dry-cured meat product, is produced from the whole muscle and/or muscles obtained from certain parts of beef and water buffalo carcasses. The purpose of this study was to determine the effects of different levels of sodium nitrite on changes in the physicochemical and microbial quality during the production of pastırma. The changes in residual nitrite, salt, pH, moisture, thiobarbutiric acid reactive substances (TBARS), colour (L*, a*, b*), total aerobic mesophilic bacteria (TAMB), lactic acid bacteria (LAB), Micrococcus/Staphylococcus (M/S), mould-yeast (M-Y), and Enterobacteriaceae counts of pastırma with 0, 50, 100 and 150 ppm sodium nitrite were determined during the production. The nitrite levels and the production stages had significant effects (p<0.01) on residual nitrite, TBARS, pH, salt, and colour values. The TBARS values of the pastırma with nitrite were significantly lower (p<0.05) than the control. The final TAMB, LAB, M/S, and M-Y counts of pastırma with 150 ppm nitrite were significantly (p<0.05) lower than the control. Also, the a* (relative redness) values of control pastırma were significantly lower (p<0.05) than the pastırma with nitrite. The production stages had a significant effect (p<0.01) on the moisture.

Changes in the Physico-chemical and Microbial Quality during the Production of Pastırma Cured with Different Levels of Sodium Nitrite

Muhammet Irfan Aksu,Ebru Erdemir,Neslihan Cakici 한국축산식품학회 2016 한국축산식품학회지 Vol.36 No.5

Pastırma, a dry-cured meat product, is produced from the whole muscle and/or muscles obtained from certain parts of beef and water buffalo carcasses. The purpose of this study was to determine the effects of different levels of sodium nitrite on changes in the physico-chemical and microbial quality during the production of pastırma. The changes in residual nitrite, salt, pH, moisture, thiobarbutiric acid reactive substances (TBARS), colour (L*, a*, b*), total aerobic mesophilic bacteria (TAMB), lactic acid bacteria (LAB), Micrococcus/ Staphylococcus (M/S), mould-yeast (M-Y), and Enterobacteriaceae counts of pastırma with 0, 50, 100 and 150 ppm sodium nitrite were determined during the production. The nitrite levels and the production stages had significant effects (p<0.01) on residual nitrite, TBARS, pH, salt, and colour values. The TBARS values of the pastırma with nitrite were significantly lower (p<0.05) than the control. The final TAMB, LAB, M/S, and M-Y counts of pastırma with 150 ppm nitrite were significantly (p<0.05) lower than the control. Also, the a* (relative redness) values of control pastırma were significantly lower (p<0.05) than the pastırma with nitrite. The production stages had a significant effect (p<0.01) on the moisture.

Experimental evaluation of different spectral methods for damage estimation of an electrical panel bracket mounted on a military wheeled vehicle

Mehmet Sefa Gümüş,Abdullah Erdemir,Veysel Alver,Mete Kalyoncu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.12

This study evaluates different frequency domain vibration fatigue methods by verifying the results of the analyses with the experimental data on the bracket of an electrical panel mounted on a military vehicle. Loadings are defined considering composite wheeled vehicle vibration exposure as stated in the MIL-STD-810G Standard. The electrical panel and the bracket are simulated by FEM. Response PSDs are created on critical points. The experiment is carried out by using a uniaxial electrodynamic shaker. In this study, the Dirlik method proposes the most reliable and accurate fatigue life, while the Wirsching-Light method overestimates. Ortiz-Chen has made a very conservative prediction among other methods in this case study.

Fortune of temporary ileostomies in patients treated with laparoscopic low anterior resection for rectal cancer

Mustafa Haksal,Nuri Okkabaz,Ali Emre Atici,Osman Civil,Yasar Ozdenkaya,Ayhan Erdemir,Nihat Aksakal,Mustafa Oncel 대한외과학회 2017 Annals of Surgical Treatment and Research(ASRT) Vol.92 No.1

Purpose: The current study aims to analyze the risk factors for the failure of ileostomy reversal after laparoscopic low anterior resection for rectal cancer. Methods: All patients who underwent a laparoscopic low anterior resection for rectal cancer with a diverting ileostomy between 2007 and 2014 were abstracted. The patients who underwent and did not undergo a diverting ileostomy procedure were compared regarding patient, tumor, treatment related parameters, and survival. Results: Among 160 (103 males [64.4%], mean [± standard deviation] age was 58.1 ± 11.9 years) patients, stoma reversal was achieved in 136 cases (85%). Anastomotic stricture (n = 13, 52.4%) was the most common reason for stoma reversal. These were the risk factors for the failure of stoma reversal: Male sex (P = 0.035), having complications (P = 0.01), particularly an anastomotic leak (P < 0.001), or surgical site infection (P = 0.019) especially evisceration (P = 0.011), requirement for reoperation (P = 0.003) and longer hospital stay (P = 0.004). Multivariate analysis revealed that male sex (odds ratio [OR], 7.82; P = 0.022) and additional organ resection (OR, 6.71; P = 0.027) were the risk factors. Five-year survival rates were similar (P = 0.143). Conclusion: Fifteen percent of patients cannot receive a stoma reversal after laparoscopic low anterior resection for rectal cancer. Anastomotic stricture is the most common reason for the failure of stoma takedown. Having complications, particularly an anastomotic leak and the necessity of reoperation, limits the stoma closure rate. Male sex and additional organ resection are the risk factors for the failure in multivariate analyses. These patients require a longer hospitalization period, but have similar survival rates as those who receive stoma closure procedure.

Complementary neutron and x-ray reflectivity studies of “near-frictionless” carbon films

Johnson, Jacqueline A.,Park, Sungkyun,Roy, Sujoy,Sinha, Sunil K.,Erdemir, Ali,Eryilmaz, Osman L.,Woodford, John B. American Institute of Physics 2007 JOURNAL OF APPLIED PHYSICS - Vol.101 No.12