Browsing by Author "Kurt K."
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Item Luminescence characterisation of defects in pld alumina and copper implanted silica(2002) Wu Z.; Türkler A.; Brooks R.; Hole D.E.; Townsend P.D.; Köster S.F.; Kurt K.; Gonzalo J.; Suarez-Garcia A.Luminescence is reported for alumina and Al2O3:Cu films grown by pulsed laser deposition and is contrasted with luminescence from Cu ion implanted silica. The implanted samples display numerous emission bands with at least two associated to charge states or the Cu ions. The relative band intensities are altered by thermal treatments. In the case of the thin films the signals are sensitive to the growth conditions and show evidence for trapped Ar nanoparticles, from argon used as a background gas during film growth. Thus in both thin film and ion implanted material the luminescence offers a route to monitor the state of the defects and the copper impurity ions. © 2002 Published by Elsevier Science B.V. © 2002 Elsevier Science Ltd. All rights reserved.Item Item A new species of Zachaeus C.L. Koch from Turkey (Opiliones, Phalangiidae)(Pensoft Publishers, 2015) Kurt K.; Koç H.; Yağmur E.A.A new species of harvestmen, Zachaeus seyyari sp. n. (Opiliones, Phalangiidae), is described and illustrated on the basis of both sexes from Şırnak Province in Turkey. Differences between the new species and related species are indicated. Photographs of its characteristic structures are also provided. © 2015, Kemal Kurt et al.Item Two new records for Turkish harvestmen Fauna (Arachnida: Opiliones)(American Entomological Society, 2015) Kurt K.; Koç H.; Yaʇmur E.A.Two harvestmen species, Mediostoma haasi (Roewer, 1953) and Phalangium armatum Snegovaya, 2005, are recorded in Turkey for the first time. Their description, characteristic features, distributions, measurements and photographs of genitalia and general habitus of both sexes are presented.Item Mediostoma izmirica sp. nov.: A new harvestman species (Arachnida, Opiliones, Nemastomatidae) from Turkey(Turkiye Klinikleri Journal of Medical Sciences, 2016) Snegovaya N.Y.; Kurt K.; Yağmur E.A.A new harvestman species of the genus Mediostoma Kratochvil, 1958, Mediostoma izmirica sp. nov., is described and illustrated based on males and females from İzmir Province, Turkey. Differences between the new species and other species of the genus Mediostoma are indicated. Scanning electron microscope photographs of its characteristic structures are also given. © TÜBİTAK.Item A comparison of cancer stem cell markers and nonclassical major histocompatibility complex antigens in colorectal tumor and noncancerous tissues(W.B. Saunders, 2016) Özgül Özdemir R.B.; Özdemir A.T.; Oltulu F.; Kurt K.; Yiğittürk G.; Kırmaz C.Colorectal carcinoma (CRC) is one of the most fatal types of cancer in both women and men, and, unfortunately, patients are often diagnosed at an advanced stage. Cancer stem cells (CSCs) are associated with poor prognosis, metastasis, and recurrence, as well as chemotherapy and radiotherapy resistance. Therefore, different treatment alternatives are needed to facilitate the elimination of CSCs. One such approach is immunotherapy; however, tumor cells can evade immune cells by alteration of the expression patterns of human leukocyte antigens (HLA). In this study, we immunohistochemically investigated the expression patterns of CSC-specific markers CD44, CD133, Nanog, and Oct3/4, and immunosuppressive molecules HLA-G and -E in advanced CRC tumor tissues and noncancerous colon biopsies. We found significantly increased CD44, Nanog, Oct3/4, HLA-G, and HLA-E expression in the CRC tumor tissues compared with the noncancerous colon biopsies. These findings suggest that some tumor cells may be CSC-like and that the increased expression of HLA-G and HLA-E may be considered as an immune-evasive adaptation. Therefore, the nonclassical major histocompatibility complex class Ib antigens HLA-G and HLA-E may be potential targets in the elimination of CRC-CSCs. However, more detailed studies are required to support our findings. © 2016 Elsevier Inc.Item Optically Stimulated Luminescence (OSL) dosimetric properties of Li2B4O7:Ag,Gd and its relationship with thermoluminescence (TL) glow-curves(Elsevier Ltd, 2018) Ozdemir A.; Can N.; Kurt K.; Yegingil Z.The aim of this work was to develop a new lithium tetraborate luminophore with impurities that are strong co-activators for Optically Stimulated Luminescence (OSL) and to investigate its dosimetric properties using OSL method. Li2B4O7:Ag,Gd phosphor consisting of polycrystalline powder was synthesized using Solution Combustion Synthesis method. The structural characterization of the synthesized phosphor was performed using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) methods. OSL dosimetry properties as a function of step-annealing procedure, radiation dose response, reproducibility of response and loss of stored signal in dark were investigated. Thermoluminescence (TL) glow curve of Li2B4O7:Ag,Gd phosphor consists of two separated glow peaks located at ∼80 and ∼210 °C with a heating rate of 2 °C/s. The traps responsible for these two TL peaks in Li2B4O7:Ag,Gd phosphor were found to be optically sensitive. Li2B4O7:Ag,Gd exhibits high OSL sensitivity and a good OSL signal reproducibility to ionizing radiation. The beta dose-response was performed in the range from 0.1 Gy to 500 Gy. The time-integrated total OSL signal intensity increases linearly with increasing dose from ∼6 Gy to 500 Gy. The minimum detectable dose was found to be ∼17.1 ± 0.9 μGy. The stored energy increased ∼6 % within 4 weeks following a strong fading value of 27 % of the initial OSL intensity after 24 h. Indeed, the X-ray Luminescence (XL) emission spectra are the characteristic of the expected f-f transitions. Luminescence spectrum of Gd doped Li2B4O7 exhibits major red emissions (590 nm, 607 nm, 621 nm) and a weak blue emission (450 nm) along with the emission bands from undoped Li2B4O7. These results strongly suggest that the luminescence properties of Li2B4O7:Ag,Gd deserves more attention as possible dosimeter material. Explanations of many TL/OSL phenomena observed in the study of Li2B4O7:Ag,Gd phosphor and improvements based on the better knowledge in the mechanism of TL/OSL in Li2B4O7:Ag,Gd, a boron-based compound were achieved by this study. © 2018Item Characterization and some fundamental features of Optically Stimulated Luminescence measurements of silver activated lithium tetraborate(Elsevier B.V., 2018) Ozdemir A.; Altunal V.; Guckan V.; Can N.; Kurt K.; Yegingil I.; Yegingil Z.A new lithium tetraborate (Li2B4O7 or abbreviated as LTB) material was produced by adding various concentrations of Ag impurities to allow better luminescent properties using the solution combustion synthesis (SCS) method. The formation of single phase LTB was confirmed using X-ray Diffraction (XRD) data and Scanning Electron Microscopy (SEM) analysis indicated the existence of a tetragonal crystalline domain. Two broad band emissions located at ∼ 272 nm (near UV region) and 526 nm (green region) were observed from room temperature photoluminescence (PL) under 205 nm excitation The synthesized material consisted of polycrystalline LTB with 1 wt% Ag (abbreviated herein as LTB:Ag) exhibits considerable thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) which is several times more sensitive to beta radiation than the other concentrations attempted. It was determined that the OSL signal has been a collection of three component signals. A step-preheating procedure to investigate the depth of the trapping centers associated with the OSL signal was carried out. We suggest that the TL peak at 200 °C mainly contributes to the OSL signal. It was observed that the total OSL area shows a linear dose response for beta doses ranging from 1 to 100 Gy. The minimum detectable dose (MDD) value was found to be around 3 mGy using the total OSL area. Under optimum conditions (irradiation with beta-rays), the reproducibility of total OSL area was determined with a −3% deviation at the end of the 9th irradiation-blue light stimulation-readout cycle. The dark storage stability of the total OSL signals was investigated and fading of the total OSL area was found to be approximately 25% after one week. The trap depth corresponding to the OSL signal was found to be 0.99 eV and 0.94 eV using various heating rate and isothermal annealing methods, respectively. Finally, silver doped lithium tetraborate is shown to have promise as an optically stimulated luminescent dosimeter, particularly in medical and personal applications. © 2018 Elsevier B.V.Item Rafalskia azizsancari sp. n., a new harvestman (Opiiiones: Phaiangiidae) from Turkey(Entomologica Fennica, 2019) Kurt K.; Yaǧmur E.A.; Tezcan E.A new harvestman species, Rafalskia azizsancari sp. n., is described and illustrated based on male specimens collected from Bozdaglar Mountains, Izmir Province, Turkey. Most important differences between the new species and the three other species of the genus are included. © Entomologica Fennica. 23 April 2019.Item Redescription and New Record of the Harvestman Lacinius insularis Roewer, 1923 (Opiliones: Phalangiidae) from Turkey(American Entomological Society, 2019) Kurt K.; Yaǧmur E.A.Lacinius insularis Roewer, 1923, is recorded for the first time as part of the Turkish harvestmen fauna. Prior to this, the species was only known from the island of Crete in Greece. The new collections were made on Nif mountain in İzmir Province (far western Turkey). In this study, L. insularis is redescribed based on adults from Turkey. Its detailed description, morphological characteristics, distribution and measurements are given. Also, genitalia, body dorsal view, chelicerae, and pedipalp are illustrated. In addition, this species is compared with similar species. © 2019 American Entomological Society. All rights reserved.Item Description of the Unknown Female of the Harvestman Rafalskiaazizsancari Kurt, Yagmur & Tezcan, 2019 (Arachnida: Opiliones: Phalangiidae) from Turkey(American Entomological Society, 2023) Kurt K.; Yagmur E.A.; Kurt P.The female of Rafalskia azizsancari Kurt, Yagmur & Tezcan, 2019, previously known only from the male in Turkey, is now described based on new material from Ödemiş District, Izmir Province, Turkey. Detailed morphological descriptions, photographs and illustration of the female ovipositor are provided. © 2023 American Entomological Society. All rights reserved.