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.

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.

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.

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

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.

Evaluation of Overactive Bladder in Male Antidepressant Users: A Prospective Study

Volkan Solmaz,Sebahattin Albayrak,Arslan Tekatas,Dürdane Aksoy,Yusuf Gençten,Sema İnanır,Fikret Erdemir 대한배뇨장애요실금학회 2017 International Neurourology Journal Vol.21 No.1

Purpose: In this study, we investigated overactive bladder (OAB) functions in male patients who used antidepressant drugs (ADs) that were previously examined in female patients, based on conflicting data in literature regarding the effects of AD on OAB and the differences between male and female urinary system physiologies (anatomical and hormonal). Methods: The study included 202 male patients (a control group of 90 healthy subjects, and an experimental group of 112 patients taking ADs for different disorders). All the patients completed the overactive bladder-validated 8 (OAB-V8) questionnaire, the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF), and the Beck Depression Inventory (BDS). Results: The OAB-V8, ICIQ-SF, and BDS scores for the antidepressant users were significantly higher than those of the control group. The highest prevalence of OAB symptoms was observed in patients taking venlafaxine (68.2%), and the lowest prevalence was in patients taking sertraline (28.0%). Moreover, the frequency of OAB between the antidepressant groups was statistically significant. The univariate logistic regression analyses showed a significant relationship between the presence of OAB, antidepressant usage, BDS score, and the age of a patient. In the multivariate logistic regression analyses, the association between the presence of OAB and antidepressant usage was statistically significant. Conclusions: The present study showed that the incidence of OAB and the severity of OAB symptoms increased in males using antidepressants for various disorders. This may have been due to unique pharmacological effects, on a molecular or individual level, of serotonin-norepinephrine reuptake inhibitors.