Browsing by Author "Uysal S."
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item A geotraverse across northwestern Turkey: Tectonic units of the Central Sakarya region and their tectonic evolution(2000) Göncüoǧlu M.C.; Turhan N.; Şentürk K.; Özcan A.; Uysal S.; Yaliniz M.K.In the Central Sakarya area of Turkey there are two main Alpine continental units, separated by a south verging ophiolitic complex which represents the root zone of the Izmir-Ankara Suture Belt. The Central Sakarya Terrane in the north includes two 'Variscan' tectonic units in its basement. The Sogut Metamorphic rocks represent a Variscan ensimatic arc complex and the Tepekoy Metamorphic rocks are characteristically a forearc-trench complex. The unconformably overlying Triassic Sogukkuyu Metamorphic rocks correspond to a part of the Karakaya Formation and are interpreted as a Triassic rift basin assemblage. These units are unconformably overlain by a transgressive sequence of Liassic-Late Cretaceous age that represents the northeastward deepening carbonate platform of the Sakarya Composite Terrane. The middle tectonic unit (the Central Sakarya Ophiolitic Complex) comprises blocks and slices of dismembered ophiolites, blueschists and basic volcanic rocks with uppermost Jurassic-Lower Cretaceous radiolarite-limestone interlayers. Geochemical data from basalt blocks suggest mid-ocean ridge basalt (MORB)- and suprasubduction-type tectonic settings within the Neotethyan Izmir-Ankara Ocean. The southern tectonic unit includes basal polyphase metamorphosed clastic rocks (Somdiken Metamorphics), intruded by felsic and basic dykes and overlain by thickbedded marbles. This assemblage is unconformably overlain by continental clastic rocks gradually giving way to thick-bedded recrystallized limestones, cherty limestones and pelagic limestones intercalated with radiolarites, and finally by a thick high pressure-low temperature (HP-LT) metamorphic synorogenic flysch sequence. This succession is identical to the passive continental margin sequences of the Tauride Platform. It is suggested that this passive margin was subducted during the Late Cretaceous in an intra-oceanic subduction zone and affected by HP-LT metamorphism. The emplacement of the allochthonous oceanic assemblages and the collision with the Central Sakarya Terrane was complete by the end of the Cretaceous.Item Application of ion implantation for synthesis of copper nanoparticles in a zinc oxide matrix for obtaining new nonlinear optical materials(2004) Stepanov A.L.; Khaibullin R.I.; Can N.; Ganeev R.A.; Ryasnyansky A.I.; Buchal C.; Uysal S.We have obtained a layered composite material by implantation of single crystal zinc oxide (ZnO) substrates with 160-keV Cu+ ions to a dose of 1016 or 1017 cm-2. The composite was studied by linear optical absorption spectroscopy; the nonlinear optical characteristics were determined by means of Z-scanning at a laser radiation wavelength of 532 nm. The appearance of the optical plasmon resonance bands in the spectra indicated that ion implantation to the higher dose provides for the formation of copper nanoparticles in a sub-surface layer of ZnO. The new nonlinear optical material comprising metal nanoparticles in a ZnO matrix exhibits the phenomenon of self-defocusing and possesses a high nonlinear absorption coefficient (β = 2.07 × 10-3 cm/W). © 2004 MAIK "Nauka/Interperiodica".Item Nonlinear optical absorption of ZnO doped with copper nanoparticles in the picosecond and nanosecond pulse laser field(OSA - The Optical Society, 2005) Ryasnyansky A.; Palpant B.; Debrus S.; Ganeev R.; Stepanov A.; Can N.; Buchal C.; Uysal S.The nonlinear absorption of nanocomposite layers based on ZnO implanted with Cu+ ions with an energy of 160 keV in implantation doses of 1016 and 1017 ions/cm2 was investigated. The values of the nonlinear absorption coefficient were measured by the Z-scan method at a wavelength of 532 nm by use of nanosecond and picosecond laser pulses. Possible optical applications of these materials are discussed. © 2005 Optical Society of America.Item Cathodoluminescence response from rare earth doped Bi4Ge 3O12(Elsevier B.V., 2009) Kibar R.; Çetin A.; Tuncer Y.; Uysal S.; Townsend P.D.; Canimoglu A.; Karali T.; Can N.Room and low temperature cathodoluminescence (CL) of rare earth doped Bi4Ge3O12 (BGO) has been recorded. Luminescence signals noted in the wavelength range (300 - 800 nm) include intrinsic broad emission bands and signals related to Eu3+, Nd3+, and Tm3+. CL measurements made on Bi4Ge3O 12 (BGO) doped with rare earth ions are reported for the temperature range 40 to 300 K with different CL excitation modulation frequencies. Dopant levels used in the present study are 1.1, 0.4, and 0.3 wt% Nd, 0.4 wt% Tm and 3 ppm Eu. All dopant levels exhibited different CL spectra with evidence for lines due to the rare-earth dopants intra-4f transitions. The temperature dependence of the intensity of the emission band is discussed.Item The comparison of insülin resistance, laboratory results and clinical factors in gestational diabetes mellitus patients with normal pregnant women without glucose intolerance; [Gestasyonel Diabetes Mellitus ve Normal Glukoz Toleransna Sahip Gebelerde nsülin Direnci, Laboratuvar Bulgular ve Klinik Faktörlerin Karşilaştirilmasi](2013) Pala H.G.; Özalp Y.; Saatli Gerçeklioglu G.; Yener A.S.; Uysal S.; Önvural A.Objective: To compare insulin resistance, laboratory results and clinical factors in gestational diabetes mellitus (GDM) patients with normal pregnant women without glucose intolerance. Material and Methods: 55 GDM patients and 50 normal pregnant women who were between 24th and 28th week of gestation included in this study. 25 patients who had not completed antenatal visits or had developed complications during pregnancy period were excluded from study. Statistical analysis was performed for the rest of 40 GDM and 40 normal pregnant women without glucose intolerance. Total cholesterol, triglyceride, high density lipoprotein (HDL), low density lipoprotein (LDL), HbAlc, glucose, insulin and c-peptide levels were measured between 24th-28th week of gestation after starvation in maternal blood sample which included into study. The relationship between these groups' measurements and the other established clinical-laboratory factors were investigated. Results: HbAlc, c-peptide, insulin, glucose, triglyceride and LDL levels were significantly higher in GDM patients compared with the group of patients with normal glucose tolerance. There was not significant difference in terms of total cholesterol and HDL levels. Calculated HOMA-IR score was significantly higher and c-peptide/insulin and c-peptide/glucose ratio were lower in GDM patients compared with the group of patients with normal glucose tolerance. Conclusion: It is accepted that increased maternal adipocyte and plasental hormones' effect aganist insulin combination had an important role in GDM pathogenesis. In this study; we ascertained that HOMA-IR was raised GDM probability 8 fold and showed that insulin resistance was one of the basic factor in GDM pathogenesis. Copyright © 2013 by Türkiye Klinikleri.Item Adiponectin levels in gestational diabetes mellitus and in pregnant women without glucose intolerance(Wroclaw University of Medicine, 2015) Pala H.G.; Ozalp Y.; Yener A.S.; Gerceklioglu G.; Uysal S.; Onvural A.Objectives: The aim of the study was to determine serum adiponectin levels among patients with gestational diabetes mellitus (GDM) and normal pregnant women without glucose intolerance, and to investigate the relationship between these levels and clinical factors at the time of the diagnosis, at delivery and in the post-partum period. Material and Methods: The subjects' serum adiponectin concentration was measured using the enzyme-linked immunosorbent assay (ELISA) method at 24th-28th week of gestation, at delivery (in maternal circulation and the umbilical cord) and 24 h after delivery. The relationship between these groups' measurements and other established clinical-laboratory factors were investigated. Results: Serum adiponectin concentrations were significantly lower (p = 0.02) in GDM patients compared with patients with normal glucose tolerance at 24th-28th week of gestation. During delivery, maternal serum adiponectin concentrations were significantly lower (p = 0.03) in GDM patients compared with patients with normal glucose tolerance. In the post-partum period, serum adiponectin concentrations were significantly higher (p = 0.009) in GDM patients compared with patients with normal glucose tolerance. Umbilical cord adiponectin concentrations were significantly lower (p = 0.005) in GDM patients compared with patients with normal glucose tolerance. Conclusions: Adiponectin concentrations in GDM patients' circulation were regulated by changes in glucose and insulin metabolism. A reduction in serum adiponectin levels seems to play a role in GDM patients' insulin resistance. © Copyright by Wroclaw Medical University.Item Composition, antioxidant, antimicrobial and enzyme inhibition activities of two Origanum vulgare subspecies (subsp. vulgare and subsp. hirtum) essential oils(Elsevier B.V., 2015) Sarikurkcu C.; Zengin G.; Oskay M.; Uysal S.; Ceylan R.; Aktumsek A.Essential oils (EOs) from Origanum vulgare subsp. vulgare (OVV) and O. vulgare subsp. hirtum (OVH) were evaluated for antioxidant activities (DPPH, ABTS, FRAP, CUPRAC, β-carotene/linoleic acid, phosphomolybdenum and metal chelating), antimicrobial and inhibitory properties against acetylcholinesterase, butrylcholinesterase, tyrosinase, α-amylase and α-glucosidase. Thymol and linalool were identified as major component in OVV and OVH essential oils, respectively. O. vulgare subsp. vulgare exhibited a strong free radical scavenging, reducing power, antimicrobial and acetylcholinesterase, butrylcholinesterase, α-amylase and α-glucosidase inhibitory activity. Interestingly, OVH possess a significant metal chelating and tyrosinase inhibitory activities. The EOs of both species exhibited moderate antibacterial and antifungal activities. The MIC values of the EOs ranged from 85.3 to 426.7. μg/mL. O. vulgare subsp. vulgare showed higher activity against Sarcina lutea with the lowest MIC (85.3. μg/mL), whereas OVH indicated strong activity for Candida albicans with MIC value of 85.3. μg/mL. The data suggest that the Origanum EOs could be used as valuable new natural agents with functional properties for food and pharmacology industries. © 2015 Elsevier B.V.Item Evaluation and follow-up of patients diagnosed with hypophysitis: A cohort study(Oxford University Press, 2024) Hacioglu A.; Karaca Z.; Uysal S.; Ozkaya H.M.; Kadioglu P.; Selcukbiricik O.S.; Gul N.; Yarman S.; Koksalan D.; Selek A.; Canturk Z.; Cetinarslan B.; Corapcioglu D.; Sahin M.; Sah Unal F.T.; Babayeva A.; Akturk M.; Ciftci S.; Piskinpasa H.; Dokmetas H.S.; Dokmetas M.; Sahin O.; Eraydln A.; Fenkci S.; Ozturk S.; Akarsu E.; Omma T.; Erkan B.; Burhan S.; Pehlivan Koroglu E.; Saygili F.; Kilic Kan E.; Atmaca A.; Elbuken G.; Alphan Uc Z.; Gorar S.; Hekimsoy Z.; Pekkolay Z.; Bostan H.; Bayram F.; Yorulmaz G.; Sener S.Y.; Turan K.; Celik O.; Dogruel H.; Ertorer E.; Turhan Iyidir O.; Topaloglu O.; Cansu G.B.; Unluhizarci K.; Kelestimur F.Objective: Primary hypophysitis might be challenging to diagnose, and there is a lack of evidence regarding optimal treatment strategies due to rarity of the disease. We aim to investigate the clinical features and compare the outcomes of different management strategies of primary hypophysitis in a large group of patients recruited on a nationwide basis. Design: A retrospective observational study. Methods: The demographic, clinical, and radiologic features and follow-up data were collected in study protocol templates and analyzed. Results: One hundred and thirteen patients (78.8% female, median age: 36 years) were included. Lymphocytic (46.7%) and granulomatous hypophysitis (35.6%) were the prevailing subtypes out of 45 patients diagnosed after pathologic investigations. Headache (75.8%) was the most common symptom, and central hypogonadism (49.5%) was the most common hormone insufficiency. Of the patients, 52.2% were clinically observed without interventions, 18.6% were started on glucocorticoid therapy, and 29.2% underwent surgery at presentation. Headache, suprasellar extension, and chiasmal compression were more common among glucocorticoid-treated patients than who were observed. Cox regression analysis revealed higher hormonal and radiologic improvement rates in the glucocorticoid-treated group than observation group (hazard ratio, 4.60; 95% CI, 1.62-12.84 and HR, 3.1; 95% CI, 1.40-6.68, respectively). The main indication for surgery was the inability to exclude a pituitary adenoma in the presence of compression symptoms, with a recurrence rate of 9%. Conclusion: The rate of spontaneous improvement might justify observation in mild cases. Glucocorticoids proved superior to observation in terms of hormonal and radiologic improvements. Surgery may not be curative and might be considered in indeterminate, treatment-resistant, or severe cases. © 2024 The Author(s). Published by Oxford University Press on behalf of European Society of Endocrinology. All rights reserved.