Yazar "Sahin, Onur" seçeneğine göre listele
Listeleniyor 1 - 12 / 12
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe The effects of therapeutic x-ray doses on mechanical, chemical and physical properties of poly methyl methacrylate(Taylor & Francis Ltd, 2013) Dogan, Derya Ozdemir; Ozguven, Yildiray; Karakus, Gulderen; Sahin, Onur; Polat, Nilufer Tulin; Yucel, Birsen; Dogan, MansurAim. The aim of this study was to investigate the effect of radiation doses very close to the human dose for oral cancers on mechanical, chemical and physical properties for poly methyl-methacrylate (PMMA). Methods. PMMA samples were divided into four different groups: no irradiated group, 25-Gy irradiated group, 50-Gy irradiated group and 75-Gy irradiated group. Each group contained nine samples. After 24 h, a three-point loading test was applied to each PMMA groups. The transverse strength and the elastic modulus were calculated using the test results. The results were analyzed statistically by using one-way analysis of variance. The structural characterizations of the PMMA samples were carried out by a Fourier Transform Infrared (FTIR) spectrophotometer to evaluate the chemical structure differences. Results. The transverse strength values of 25-Gy, 50-Gy and 75-Gy radiation groups were significantly higher than that of the no radiation group (p < 0.05). There was no significant difference among the elastic modulus values of the study groups (p > 0.05). The FTIR findings demonstrated that the irradiation process did not change the chemical structure of the PMMA polymeric materials. Conclusion. The therapeutic radiation doses increase the mechanical properties of the PMMA; however, the chemical and structural properties have no effect. When the findings of this study are taken into account, it can be said that patients can wear dentures during the radiotherapy.Öğe Medication-related osteonecrosis of the jaw: A survey of knowledge, practices and opinions of dentists(2020) Sahin, OnurAim: The aim of this study was to evaluate dentists on their knowledge on biphosphonates, medication related osteonecrosis of the jaw (MRONJ), and on the treatment approaches towards patients using bisphosphonates in the Faculty of Dentistry at İzmir Katip Celebi University. Material and Methods: This was a questionnaire-based cross-sectional study conducted on 97 dentists. The surveys consists of a total of 20 questions and four sections, with statistical analysis being used on the collected data. The Chi-square and Student-t tests were utilized to compare between the groups. The significance level was set at p 0.05.Result: There was no significant difference in terms of correct answers to the questions between the dentists with professional experience in surgical procedures (Group A), and the dentists without professional experience in surgical procedures (Group B) (p> 0.05). In the second part of the questionnaire, the dentists were asked various questions in order to measure their general knowledge regarding bisphosphonates and MRONJ. There was no significant difference between the groups in terms of correct answers (p> 0.05). In the third part of the questionnaire, surgical scenarios were presented to the dentists and generally, they preferred the option in which no procedure should be performed in patients who take intravenous (IV) bisphosphonates, regardless of the duration of use. Conclusions: Increasing the awareness of medical practitioners, dentists, and patients in the use and side effects of bisphosphonates is important for preventing MRONJ. For this purpose, training strategies related to MRONJ should be established.Öğe N-Alkylation and N,C-Dialkylation of Amines with Alcohols in the Presence of Ruthenium Catalysts with Chelating N-Heterocyclic Carbene Ligands(Amer Chemical Soc, 2015) Sahin, Zeynel; Gurbuz, Nevin; Ozdemir, Ismail; Sahin, Onur; Buyukgungor, Orhan; Achard, Mathieu; Bruneau, ChristianA series of new benzimidazolium salts and ruthenium(II) complexes containing chelating N-heterocyclic carbenes (NHCs) functionalized with a benzylic group and an acetal group were prepared. All of the synthesized compounds were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of 2c and 2d were determined by X-ray crystallography. All of the,complexes were tested in the alkylation of cyclic amine derivatives with alcohols and showed excellent activity in this reaction. Cyclic amines were alkylated with primary and heteroaromatic alcohols. The Ru-NHC Complexes also catalyzed N,C3-dialkylation of cyclic amines.Öğe Novel ruthenium(II)-N-heterocyclic carbene complexes; synthesis, characterization and catalytic application(Elsevier Science Sa, 2015) Yasar, Sedat; Karaca, Emine Ozge; Sahin, Caglar; Ozdemir, Ismail; Sahin, Onur; Buyukgungor, OrhanThe synthesis of highly active ruthenium(II) catalyst based on N-heterocyclic carbene (NHC) bearing alkyl and aryl groups is reported. The complexes are easily handled in very good yields via synthesis of silver -NHC complexes and subsequent reaction with [RuCl2(p-cymene)](2) in dichloromethane (DCM) under N-2 condition. All new compounds were characterized by LC-MSMS, elemental analysis, NMR spectroscopy and X-ray diffraction. With the development of a more efficient catalytic system for transfer hydrogenation of aryl ketones and aldehydes in mind, the catalytic performance of the Ru-NHC complexes for transfer hydrogenation was investigated. (c) 2015 Elsevier B.V. All rights reserved.Öğe Palladium Complexes with Tetrahydropyrimidin-2-ylidene Ligands: Catalytic Activity for the Direct Arylation of Furan, Thiophene, and Thiazole Derivatives(Amer Chemical Soc, 2015) Karaca, Emine Ozge; Gurbuz, Nevin; Ozdemir, Ismail; Doucet, Henri; Sahin, Onur; Buyukgungor, Orhan; Cetinkaya, BekirThe synthesis and characterization of novel 1,3-benzyl-3,4,5,6-tetrahydropyrimidin-2-ylidene-based N-hetero-cyclic carbene palladium(II) complexes (1a-d) were described. The crystal structure of trans-dichlorobis[1,3-bis(4-methylbenzyl)-3,4,5,6-tetrahydropyrimidin-2-ylidend- palladium(II) was presented. Pd(II) complexes 1a-d were tested as catalysts in the direct C5 or C2 arylation of furans, thiophenes, and thiazoles, with various aryl bromides at 150 degrees C for 1 h. These complexes exhibited moderate to high catalytic activities under the given conditions.Öğe Palladium N-heterocyclic carbene complexes: Synthesis, characterization and catalytic properties in amination(Elsevier Science Sa, 2010) Ozdemir, Ismail; Demir, Serpil; Sahin, Onur; Buyukgungor, Orhan; Cetinkaya, BekirTransmetalation has proved to be a promising procedure to obtain NHC-metal complexes, which typically involves treatment of the imidazolium salt with Ag2O to form the Ag-NHC complex, followed by transmetalation to a species such as [PdCl2(CH3CN)(2)] gave the palladium complex in which the N-heterocyclic carbene was bound to the metal center. New bis(NHC)-Pd complexes were synthesized and characterized by elemental analysis, H-1 NMR, C-13 NMR, and IR spectroscopy. The crystal and molecular structure of the trans-dichlorobis{1-(2,3,5,6-tetramethylbenzyl)-3-(2,3,4,5,6-pentamethylbenzyl)imidazolidin-2-yliden}palladium(II) complex was determined by single-crystal X-ray diffraction. The activity of the Pd(II) complexes in the coupling reaction of anilines or amines with bromobenzene was investigated. A preliminary catalytic study showed that these bis(NHC)-Pd complexes were highly active in the direct synthesis of triarylamines and secondary amines in a single step. (C) 2010 Elsevier B.V. All rights reserved.Öğe Preparation of a series of Ru(II) complexes with N-heterocyclic carbene ligands for the catalytic transfer hydrogenation of aromatic ketones(Royal Soc Chemistry, 2012) Gurbuz, Nevin; Ozcan, Emine Ozge; Ozdemir, Ismail; Cetinkaya, Bekir; Sahin, Onur; Buyukgungor, OrhanThe reaction of [RuCl2(p-cymene](2) with Ag-N-heterocyclic carbene (NHC) complexes yields a series of [(p-cymene) Ru(NHC)] complexes (2a-f). All synthesised compounds were characterized by elemental analysis, NMR spectroscopy and the molecular structure of 2a was determined by X-ray crystallography. All complexes have been tested as catalysts for the transfer hydrogenation of aromatic ketones, showing excellent activity in this reaction.Öğe Synthesis and Catalytic Activity of Novel Benzimidazolinylidene-Ruthenium(II) Complexes(Georg Thieme Verlag Kg, 2010) Demir, Serpil; Ozdemir, Ismail; Sahin, Onur; Cetinkaya, Bekir; Buyukgungor, OrhanThe reaction of [RuCl2(p-cymene)](2) with 1,3-dialkyl-benzimidazolium salts 1a-d in the presence of a small excess of cesium carbonate yields chelated eta(6)-arene, eta(1)-carbene ruthenium complexes 2a-d. All compounds were characterized by elemental analysis, NMR spectroscopy and the molecular structures of two of the complexes were determined by X-ray crystallography. The catalytic activity of RuCl2(eta(6)-arene, eta(1)-benzimidazolinylidene) complexes was evaluated in the direct arylation of 2-phenylpyridine with bromobenzene derivatives.Öğe Synthesis of novel rhodium-xylyl linked N-heterocyclic carbene complexes as hydrosilylation catalysts(Wiley, 2008) Ozdemir, Ismail; Demir, Serpil; Sahin, Onur; Buyukgungor, Orhan; Cetinkaya, BekirReaction of ortho-xylylbis(N-2,4,6-trimethylbenzylimidazolinium);xylylbis(N-butylimidazolinium) and para-xylylbis(N-2,4,6-trimethylbenzylimidazolinium); xylylbis(N-butylimidazolinium) salts with KOBut and [RhCl(COD)](2) yields ortho- and para-xylylbis{(N-alkylimidazolidin-2-ylidene)chloro(eta(4)-1,5-cyclooctadiene) rho dium(I)} complexes (2a-d). All compounds synthesized were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of the 2a and 2d were determined by X-ray crystallography. Triethylsilane reacts with acetophenone derivatives in the presence of catalytic amount of the new rhodium(I)-carbene complexes (2a-d), to give the corresponding silylethers in good yields (83-99%). Copyright (C) 2008 John Wiley & Sons, Ltd.Öğe Synthesis of palladium complexes derived from imidazolidin-2-ylidene ligands and used for catalytic amination reactions(Wiley, 2016) Karaca, Emine Ozge; Gurbuz, Nevin; Sahin, Onur; Buyukgungor, Orhan; Ozdemir, IsmailN-Aryl amination and the Buchwald-Hartwig reaction are of great synthetic and industrial interest and scientists accept their usefulness and versatility for obtaining arylamines. In this study Ag-N-heterocyclic carbene complexes were used as trans-metallation reagents for the synthesis of Pd-N-heterocyclic carbene complexes. The new Pd-N-heterocyclic carbene complexes were characterized using elemental analysis and H-1 NMR, C-13 NMR and infrared spectroscopies. The crystal structure of one, namely dichlorobis[1,3-bis(2-methylbenzyl)imidazolidin-2-yliden]palladium(II), is presented. The activity of the Pd(II) complexes in the coupling reaction of anilines or amines with bromobenzene was investigated. These complexes exhibited high catalytic activities in the direct synthesis of triarylamines and secondary amines in a single step. Copyright (C) 2016 John Wiley & Sons, Ltd.Öğe Synthesis, characterization and catalytic activity of novel N-heterocyclic carbene-palladium complexes(Royal Soc Chemistry, 2009) Dogan, Oznur; Gurbuz, Nevin; Ozdemir, Ismail; Cetinkaya, Bekir; Sahin, Onur; Buyukgungor, OrhanThe reaction of Pd(OAc)(2) with 1-(benzhydryl)-3-(alkyl) benzimidazolium salts 1a-d yields trans-bis[1-(benzhydryl)-3-(alkyl)benzimidazolin-2-ylidene]dibromopalladium(II) complexes (2a-d) which were characterized by elemental analysis, NMR spectroscopy and the molecular structures of 2b, and 2d were determined by X-ray crystallography. The catalytic activity of PdBr(2)bis(benzimidazolin-2- ylidene) complexes 2a-d was evaluated in the direct arylation reaction of benzothiazole with bromobenzene derivatives.Öğe A theoretical insight for solvent effect on myoglobin assay of W(CO)4L2 type novel complexes with DFT/TDDFT(Elsevier Science Bv, 2016) Ustun, Elvan; Demir, Serpil; Coskun, Feyzullah; Kaloglu, Murat; Sahin, Onur; Buyukgungor, Orhan; Ozdemir, IsmailNovel tetracarbonyl complexes of type W(CO)(4)L-2 (L: 4-chlorobenzylimidazoline; 4-methylbenzylimidazoline; 3,5-dimethylbenzylimidazoline; 2,4,6-trimethylbenzylimidazoline; 2,3,5,6-tetramethylbenzylimidazoline) were synthesized. Then newly synthesized novel compounds were characterized by IR, H-1 NMR, C-13 NMR and LC-MS. The characterizations of two of the complexes have also been confirmed with single crystal X-Ray diffraction and OFT optimization results of these complexes have been compared with single crystal results. We have investigated the solvent effect on the structure and metal-to-ligand charge transfer (MLCT) transitions with OFT/TDDFT calculations with ORCA package program with BP86 functional. (C) 2016 Elsevier B.V. All rights reserved.
