(k,m)-type slant helices for the null Cartan curve with the Bishop frame in E^4_1

Mehmet Bektaş,Sümeyye Gür Mazlum 호남수학회 2023 호남수학학술지 Vol.45 No.4

In this paper, we obtain (k, m)-type slant helices for a null Cartan curve with the Bishop frame in Minkowski space E^4_1

Influence of different surface treatments on bond strength of novel CAD/CAM restorative materials to resin cement

Meltem Bektaş Kömürcüoğlu,Elçin Sağırkaya,Ayça Tulga 대한치과보철학회 2017 The Journal of Advanced Prosthodontics Vol.9 No.6

PURPOSE. To evaluate the effects of different surface treatments on the bond strength of novel CAD/CAM restorative materials to resin cement by four point bending test. MATERIALS AND METHODS. The CAD/CAM materials under investigation were e.max CAD, Mark II, Lava Ultimate, and Enamic. A total of 400 bar specimens (4×1.2×12 mm) (n=10) milled from the CAD/CAM blocks underwent various pretreatments (no pretreatment (C), hydrofluoric acid (A), hydrofluoric acid + universal adhesive (Scotchbond) (AS), sandblasting (Sb), and sandblasting + universal adhesive (SbS)). The bars were luted end-to-end on the prepared surfaces with a dual curing adhesive resin cement (Variolink N, Ivoclar Vivadent) on the custom-made stainless steel mold. Ten test specimens for each treatment and material combination were performed with four point bending test method. Data were analyzed using ANOVA and Tukey’s test. RESULTS. The surface treatment and type of CAD/CAM restorative material showed a significant effect on the four point bending strength (FPBS) (P<.001). For LDC, AS surface treatment showed the highest FPBS results (100.31 ± 10.7 MPa) and the lowest values were obtained in RNC (23.63 ± 9.0 MPa) for control group. SEM analyses showed that the surface topography of CAD/CAM restorative materials was modified after treatments. CONCLUSION. The surface treatment of sandblasting or HF acid etching in combination with a universal adhesive containing MDP can be suggested for the adhesive cementation of the novel CAD/CAM restorative materials.

Double-imprinted potentiometric sensors based on ligand exchange for the determination of dimethoate

Eyüp Bektaşoğlu,Ebru Birlik Özkütük,Arzu Ersöz,Rıdvan Say 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.8

This paper describes a dimethoate imprinted polymeric potentiometric sensor for the determination of dimethoate that was designed by dispersing the dimethoate-imprinted polymer in dibutyl phthalate plasticizer and then embedded in polyvinyl chloride matrix. The method is based on molecularly imprinted polymer (MIP), which can be synthesized by using dimethoate as a template molecule, chitosan-Cd(II), and 3-mercaptopropyl-trimethoxysilane as a functional monomer and TEOS, and ephychlorohydrin as a cross-linking agent. We have studied a method for the selective binding behavior of dimethoate compounds on the surface of imprinted polymers which is prepared using ligand-exchange (LE) (chitosan-Cd(II)) monomer. The MIP-LE-1 and MIP-LE-2 based membranes have shown a detection limit of 4.3×10−6mmolL−1 and 3.5.10−5 mmolL−1, respectively. The sensor has exhibited a response time of 35min for MIP-LE-1 and 120min for MIP-LE-2. They are stable for more than three months.

Characterization of short-length multi-walled carbon nanotubes and cytotoxicity on MDA-MB-231 and HUVEC cell lines

Dinç Bircan,Ünlü Ayhan,Bektaş Muhammet 한국탄소학회 2020 Carbon Letters Vol.30 No.2

Multi-walled carbon nanotubes (MWNTs) are suitable for delivering large biomolecules with lower cytotoxicity values and low prime cost. Surface modifcations of MWNTs afect interaction with cells and proteins. Oxidation with strong acids decreases cytotoxicity of CNTs and increases protein-loading capacity. Here, after oxidation, TEM images revealed more aligned structure and carboxylated groups at the surface which decreases toxicity. Functionalized MWNTs showed more gradual degradation than the pristine MWNTs and mass loss increased by 2% in the same temperature range. Raman spectroscopy corrected graphitic structure with characteristic D and G bands at 1330 and 1579 cm−1 and increased intensity after oxidation. FTIR spectroscopy peaks at 1443 cm−1, 1560, 1640 cm−1, 2100–2200 cm−1 and 3426 cm−1 are ascribed to C–O–C vibrational stretch, C=C bonds, vibration of C≡C bonds and stretch of hydroxyl groups, respectively. The sonication�driven dispersion of in phosphate-bufered saline, distilled water and cell culture medium were detected by UV–vis–NIR spectroscopy, water-dispersed functionalized MWNTs revealed the highest absorbance value. Cytotoxicity of MWNTs was investigated before and after functionalization in breast cancer (MDA-MB-231) and human vein endothelial (HUVEC) cells. Relatively low-toxicity results were obtained in functionalized MWNTs and cellular uptake of MWNTs were corrected with fuorescent imaging of cells and cell lysates. Protein-loading capacity of fsMWNTs (functionalized short-length multi-walled carbon nanotubes) was evaluated by using bovine serum albumin (BSA) and with an equal amount of fsMWNTs and BSA; 36% binding yield was obtained. Protein corona after covalent functionalization potentially lowered cytotoxicity up to 6%

Elastic-plastic thermal stress analysis of an aluminum composite disc under parabolic thermal load distribution

Gürkan Altan,Muzaffer Topçu,Numan Behlül Bektaş,Burçin Deda Altan 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.12

An elastic-plastic thermal stress analysis was carried out on an orthotropic aluminum metal matrix composite disc with a hole by using an analytical solution. The thermal load distribution was chosen to vary parabolically from inner surface to outer surface. An aluminum composite disc reinforced curvilinearly by steel fibers was produced under hydraulic press. The mechanical properties of the composite disc were obtained from experiments by using strain gauges. A computer program was developed to calculate the thermal stresses under a parabolic temperature from inner surface to outer surface. The material was assumed to be non-linear hardening. The elastic-plastic solution was performed for the plastic region expanded around the inner surface by an analytical method. The magnitude of the tangential stress component for elastic and elastic-plastic was higher than the magnitude of the radial stress component. Besides, the tangential stress component was compressive on the inner surface and tensile on the outer surface. The magnitude of the tangential residual stress component was the highest on the inner surface of the composite disc. The plastic region began at the inner surface of disc.

Tacrolimus toxicity-related chorea in an infant after liver transplantation

Fevzi Kahveci,Tanıl Kendirli,Anar Gurbanov,Edin Botan,Meltem Koloğlu,Ömer Bektaş,Zarife Kuloglu,Deniz Balcı,Aydan Kansu 대한중환자의학회 2022 Acute and Critical Care Vol.37 No.3

Carcinoma of the Tongue: A Case-control Study on Etiologic Factors and Dental Trauma

Bektas-Kayhan, Kivanc,Karagoz, Gizem,Kesimli, Mustafa Caner,Karadeniz, Ahmet Nafiz,Meral, Rasim,Altun, Musa,Unur, Meral Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.5

Background: Carcinoma of the tongue is the most common intra-oral malignancy in Western countries. Incidence and mortality rates have increased in recent years, and survival has not improved. This study aimed to determine etiologic factors for tongue cancer with age-sex matched case-control data. Materials and Methods: 47 patients with carcinoma of the tongue referred to our oral medicine clinic between years 2005-2006 were analyzed and compared with control group data. The medical records, including family history of cancer, dental trauma, and history of abuse of alcohol and tobacco products was recorded for all subjects. Chi square comparison tests and linear regression analysis were performed using the SPSS program for statistics. Results: Patient and randomly selected control groups each consisted of 30 male and 17 female subjects with mean ages 53.2 (${\pm}12.6$) and 52.6 (${\pm}11.5$) years respectively. Smoking and alcohol abuse proportions were significantly higher in the patient group (p=0.0001, p<0.0001 respectively). Chronic mechanical trauma was observed in 44.7% of the patients and 17.0% of the control group (p=0.004). Similarly, family history of cancer of any type (for the first degree relatives) was found to be more common in the patient group (p=0.009). On regression analysis, alcohol abuse, family history of cancer, smoking, chronic mechanical traumas appeared as significant etiologic factors (p=0.0001). Conclusions: We believe that field cancerization may become evident in oral and oropharyngeal mucosa with multiple steps of molecular changes starting from the first sign of dysplasia with chronic exposure to etiological factors. Chronic trauma cases need particular attention to search for very early signs of cancer.

A Tie-Over Dressing Using a Silicone Tube to Graft Deep Wounds

Bektas, Cem Inan,Kankaya, Yuksel,Ozer, Kadri,Baris, Ruser,Aslan, Ozlem Colak,Kocer, Ugur Korean Society of Plastic and Reconstructive Surge 2013 Archives of Plastic Surgery Vol.40 No.6

Background The most common cause of skin graft failure is the collection of blood or serous fluid underneath the graft. In our study, we describe the use of silicone tube for tie-over dressing to secure the skin graft margins with the aim of decreasing loss of the skin graft, particularly in grafting of deep wounds. Methods Between March 2008 and July 2011, we used this technique in 17 patients with skin defects with depths ranging from 3.5 to 8 mm (mean, 5.5 mm). First, the skin graft was sutured with 3/0 silk suture material from its corners. Then, a silicone round drain tube was sutured with 3/0 absorbable polyglactin 910 over the margins of the graft. Finally, long silk threads were tied over the bolus dressing, and the tie-over dressing was completed in the usual fashion. Results The mean follow-up was 7 months (range, 2-10 months) in the outpatient clinic. Graft loss on the graft margins due to hematoma or seroma was not developed. The results of adhesion between the graft and wound bed peripherally was excellent. Conclusions In our study, we suggest that use of a silicone tube for additional pressure on the edges of skin grafts in case of reconstruction of deep skin defects.

Anxiety, Depression Levels and Quality of Life in Patients with Gastrointestinal Cancer in Turkey

Bektas, Didem Kat,Demir, Sati Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.2

Background: Cancer is a major public health problem in many parts of the world. Gastrointestinal (GI) cancers are responsible for 20% of all cancer-related deaths. In Turkey, stomach cancers account for 8.9%, colon cancer for 6.9%, and pancreatic cancer for 5.9%. This study examined the anxiety-depression levels and the quality of life of patients with GI cancer. Materials and Methods: This descriptive study was carried out on 335 adult patients who had gastrointestinal cancer and who were hospitalized in medical oncology clinics. Data were collected by using hospital anxiety and depression scale, EORTC QLQ C-30 and a patient information form. Results: Patients who were male and secondary school graduates/graduates/postgraduates experienced more functional difficulties. Patients with poor economic status experienced more symptoms. Patient general wellbeing decreased with increase disease duration. The level of functional difficulties decreased with an increasing number of hospital stays. Anxiety scores increased with decreasing age. Both anxiety and depression scores increased with increasing disease duration. Patients who were female, single/widowed/divorced, and literate/elementary school graduates had higher anxiety and depression scores. Life quality decreased with increasing anxiety and depression. Conclusions: Patients should be supported to prevent anxiety and depression, and should be followed up with this in mind.

Effects of Perceived Smoking-Cancer Relationship and Cardiovascular Health Attitudes on Childrens' Views of Smoking

Bektas, Ilknur,Bektas, Murat,Selekoglu, Yasemin,Kudubes, Asli Akdeniz,Altan, Sema Sal,Ayar, Dijle Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.7

Background: This study was conducted with the aim of determining how students' perceived smoking-cancer relationship and cardiovascular health attitudes affect childrens' views of smoking. Materials and Methods: The sample of this descriptive-cross sectional study comprised 574 subjects between the ages of 11-15. The data were collected using the Children's Cardiovascular Health Promotion Attitude Scale and the Children's Decisional Balance Measure for Assessing and Predicting Smoking Status. Correlation and logistic regression were used for analysis. Results: It was determined that a statistically significant relationship exists between the attitudes of children towards smoking and their ideas about the relationship of smoking with cancer, which is negative and low (r=-0.223). There was also a statistically significant relationship between their attitudes towards cardiovascular health and their attitudes towards smoking, again at a low level (r=0.257). It was determined that children with ideas about smoking and cancer were 9.4 times less likely to have positive/negative attitudes towards smoking, while positive attitudes towards cardiovascular health made negative attitudes towards smoking 3.9 times less likely. Conclusions: It was determined that the attitudes of students towards cardiovascular health and their perceptions of smoking and cancer reduced the positive perceptions towards smoking.