Sürdürülebilir Kalkınma Amaçları

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Araştırmacılar(3)

• Coldur, Fatih
• Özdokur, Kemal Volkan
• Solakyildirim, Kemal

• ArticleAçık Erişim2025/r/ebyu/19557
  Assessment of Heavy Metal Contamination in Sugar Beet (Beta Vulgaris) Plant Along Erzincan–Erzurum Highway in Eastern Anatolia Region

  Ertugay, Mustafa Fatih; Ozdokur, Kemal Volkan; Ertugay, Neşe

  In this study, it was aimed to determine the traffic and agricultural activity-induced heavy metal including arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr) and lead (Pb) pollution of sugar beet plants (Beta Vulgaris) grown along the Erzincan-Erzurum D100-25 highway and to reveal the possible change in the amount of heavy metals in sugar beet plants depending on distance to the highway. For this purpose, sugar beet plants were collected from 5 points of 10, 20, 30, 40 and 50 meters away from the highway and heavy metal levels of the samples were determined by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that sugar beet plants were contaminated with various heavy metals such as Cr (585.5-2687.8 µg kg-1) > Co (143.4-500.7 µg kg-1) > Pb (52.1-476.7 µg kg-1) > As (9.1-112.4 µg kg-1) > Cd (4.4-65.2 µg kg-1) depending on the distance from the highway. It was determined that heavy metal pollution levels in sugar beet plants decreased with distance from the motorway and there was a high correlation (As: 0.977; Cd: 0.944; Co: 0.995; Cr: 0.989 and Pb: 0.999) between distance and heavy metal content.

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• ArticleAçık Erişim2022/r/ebyu/20566
  Kil Esaslı Bütünüyle-Katı-Hal Kompozit Kurşun (II)-Seçici Potansiyometrik Elektrot

  Caglar, Bulent; Topcu, Cihan; Güner, Eda Keles; Ozdokur, Kemal Volkan; Cubuk, Osman; Çoldur, Fatih; Doğan, Bilge; Özdemir, Agah Oktay

  Bentonit kili XRD, FTIR ve SEM-EDX teknikleriyle karakterize edildi. Karakterize edilen kil bütünüyle katı hal kompozit potansiyometrik elektrot yapımında iyonofor madde olarak kullanılmış ve kilin potansiyometrik uygulaması gerçekleştirilmiştir. Elektrodun Pb2+ iyonuna karşı, diğer yaygın inorganik katyonlarla karşılaştırıldığında oldukça duyarlı ve seçici potansiyometrik bir cevap sergilediği gözlemlenmiştir. Membran optimizasyon çalışmaları neticesinde en iyi potansiyometrik performans özellikleri sergileyen bileşimin kütlece %65.0 grafit, %5.0 çok duvarlı karbon nanotüp, %20.0 iyonofor (bentonit) ve %10.0 parafin yağı olduğu belirlenmiştir. Pb2+ seçici kompozit elektrodun 1.0×10-5 ˗ 1.0×10-1 M konsantrasyon aralığında doğrusal cevap sergilediği, doğrusal çalışma aralığında standart Pb2+ çözeltilerine karşı her 10 katlık konsantrasyon değişiminde ortalama 31 mV potansiyel fark sergilediği gözlenmiştir. Elektrodun tayin sınırı 9.0×10-6 M olarak hesaplanmıştır. Elektrodun cevap zamanının oldukça kısa olduğu (~5 s) potansiyometrik cevabın ve tekrarlanabilirliğinin de oldukça yüksek olduğu ortaya konmuştur.

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• ArticleAçık Erişim2022/r/ebyu/20496
  A Simple and High Throughput Methodology for Simultaneous Determination of Levodopa and Carbidopa

  Ozdokur, Kemal Volkan; Ertaş, Fatma Nil; Kırlangıç, İrem Aydın

  Parkinson's disease (PD) is a degenerative disorder of the central nervous system. The motor symptoms of PD disease result from the death of dopamine-generating cells in a region of the mid brain and the dopamine precursor levodopa (L-Dopa) is used for the treatment. Carbidopa (Car) is administered in association with L-Dopa in pharmaceutical formulation as an inhibitor on the decarboxylase activity. Thus, their simultaneous determination is of great importance because of their co-existence in pharmaceutical preparations. Present study deals with a simple method development for simultaneous voltammetric determination of L-Dopa and Car at a pencil graphite electrode (PGE) via monitoring the reduction peak of L-Dopa and the second oxidation peak of Car. The sensitivity of the method was found comparable to other methods depending on the sophisticated electrode modifications and the limits of detection were calculated as sub micromolar levels.

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• ArticleAçık Erişim2021/r/ebyu/20771
  Evaluation Of BIS-GMA Release In Different Types Of Composites

  Egil, Edibe; Karaca, Serhat; Duman, Canan; Ozdokur, Kemal Volkan; Ceyran, Ertuğrul

  BIS-GMA is frequently is involved in the structure of composite materials and may remain unpolymerized after polymerization. Residual Bis-GMA has harmful effects, it is crucial to determine the amounts released monomer from dental materials. The aim of this study is to compare residual BIS-GMA amounts in three types of composite. A total of 45 (n=15) composite (Filtek Ultimate Universal Restorative,3M ESPE,Germany), flowable composite (Nextcomp Flow,Meta Biomed,Kore), bulk fill composite(Tetric N Ceram, Ivoclar,Lichtenstein) cylindrical samples were polymerized in Teflon molds in accordance with the manufacturer's instructions. The samples were placed in 1.5ml ethanol (Carlo Erba, Pharm. Grade, 99.9%) and kept at 37oC. Monomer release of the samples was evaluated on the first, third and seventh days using the High Performance Liquid Chromatography technique. BIS-GMA release was shown with the highest amounts within all groups on the first day. The elution in composite fillings was significantly lower than the other materials on the first day(p<0.05). The highest total emission rates were observed in the flowable composite. The material selected in clinical practice should be considered because the monomer release may vary depending on the composite type.

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• ArticleAçık Erişim2021/r/ebyu/20763
  Investigation of Schiff Bases Containing Acryloyl Moiety as Ionophore in Potentiometric Ion-Selective Sensors

  Özkınalı, Sevil; Cubuk, Osman; Kıranlıoğlu, Gülüzar; Çoldur, Fatih

  In this study, all-solid-state chromium (III) selective potentiometric poly(vinylchloride) (PVC) membrane sensors were constructed by using the newly synthesized ionophores called (E)-4-((4–nitrophenylimino) methyl) phenyl acrylate (A1), (E)-4-((4-chlorophenylimino) methyl) phenyl acrylate (A2) and (E)-4-(4- hydroxybenzylideneimino) benzoic acid acrylate (A3). The most suitable membrane composition, which has the best potentiometric characteristics, was examined by using membrane cocktail coated electrodes containing the ionophores, o-nitrophenyloctyl ether (o-NPOE), bis(2-ethylhexyl) sebacate (DOS), dibutyl phthalate (DBP), dioctyl phthalate (DOP) and PVC. In addition, the effect of potassium tetrakis(4-chlorophenyl) borate (KTpClPB) and sodium tetraphenylborate (NaTPB) as ionic additives was investigated to determine optimum membrane composition. The optimum membrane composition was determined as 1.0 % (w/w) A2, 67.0 % (w/w) o-NPOE, and 32.0 % (w/w) PVC. On the condition of pH 3.50 the prepared electrode exhibited a linear response over the concentration range of 1.3×10-7−1.0×10-1 M chromium (III) ion solutions (R2=0.9938) with a sensitivity of 27.1 ± 0.8 mV/ decade, detection limit of 6.3×10-8 M and short response time of ≤10 s. The influences of some widely used cation species over electrode responses were studied. In order to investigate whether the proposed electrode could be used analytically, potentiometric determination of chromium (III) ion was carried out in real samples. The results were statistically compared with the Inductively Coupled PlasmaMass Spectrometry (ICP-MS) method.

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• ArticleAçık Erişim2019/r/ebyu/22262
  Oxygen Reduction at Palladium Decorated Copper-Molybdenum Oxide Modified Glassy Carbon Electrode

  Özdokur, K. Volkan

  In this study, metal nanoparticles decorated metal oxide electrode was fabricated via electrochemicaltechnique. Firstly, molybdenum/copper oxide was electrochemically deposited on the bare glassy carbonelectrode surface. Then palladium nanoparticles were modified on this oxide functionalized surface byconsecutive potential cycles. Resulting composite electrode was characterized with scanning electronmicroscopy. The proposed composite electrode was employed for electrocatalytic oxygen reduction inalkaline media. As compared to bare electrode, the resulting composite surface has tremendous effect onoxygen reduction in terms of accelerated peak current values.

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• ArticleAçık Erişim2019/r/ebyu/22244
  Arbutin’in yeni kaynakları: Onobrychis nitida and Onobrychis galegifolia

  Özdokur, Kemal Volkan; Akşit, Hüseyin; Köksal, Ekrem; Şimşek, Samed

  Arbutin (4-Hidroksifenil-β-D-glukopiranozit), hidrokinonun mono glikozidik formudur ve cilt beyazlatma ve çil giderme özellikleri nedeniyle kozmetiklerde uzun süredir yaygın olarak kullanılmaktadır. Bu çalışmada; arbutin flash kromatografi kullanılarak Onobrychis galegifolia'nın metanol ekstraktından izole edilmiştir. Arbutin yapısı, 1 H ve 13C -NMR spektroskopisi ve ayrıca 2D NMR teknikleri ile aydınlatıldı. Ek olarak, O. galegifolia ve O. nitida türlerinde bulunan arbutinin kantitatif analizi HPLC-DAD kullanılarak yapıldı. Sonuçlara göre, O. galegifolia ve O. nitida'nın metanol ekstraktlarının arbutin içeriği sırasıyla 212.02 ve 196.46 mg/g ekstrakt olarak bulundu. Ayrıca, O. galegifolia ve O. nitida'nın soğuk su ekstraktlarının arbutin içeriği 128.2 ve 99.40 mg/g ekstrakt olarak bulundu. Kuru ağırlıklardaki arbutin miktarı, yaklaşık% 5.66 ila% 6.86 arasında hesaplandı.

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• ArticleAçık Erişim2019/r/ebyu/22241
  Fast Punicalagin Content Analysis of Various Brands of Pomegranate(Punica granatum L.) Juices by UPLC-MS

  Solakyildirim, Kemal

  Punica granatum L., commonly known as pomegranate, has a good source of bioactive polyphenolic compounds that has been widely used as a traditional Chinese herbal medicine owing to their important biological properties including cardiovascular disease, arthritis, diabetes, and cancer. Commercial pomegranate juice is generally obtained via pressing whole pomegranate and its peels. Then, the most abundant ingredient, punicalagin, can be extracted into the juice. Ho-wever, punicalagin levels may vary in commercial pomegranate juice and it can range from 0.017 to 2 g/L. In this study, we analyzed punicalagin content from six different brands of pomegranate juices by using UPLC-MS method. First, punicalagin standards were prepared from 50 μM to 5 μM in buffer A (0.1% formic acid in water) and standard calibration curve was created. After that, three mass tune parameters including ionization voltage, desolvation temperature and source tempera-ture of ESI source were optimized to obtain better peak shapes and correct quantification of the α- and β- isomer peaks of punicalagin. After analysis of six different brands of pomegranate juices, it was seen that punicalagin levels from different juice samples varied from 0.007 to 0.3 g/L.

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• ArticleAçık Erişim2019/r/ebyu/21885
  Poliprol-Karbon Nanotüp Modifiye Elektrotta Farmasötik Tabletlerde Metamizol Sodyumun Voltammetrik Tayini

  Özdokur, Kemal Volkan; Koçak, Çağrı Ceylan

  Polipirol-karbon nanotüp (PPy-CNT) kompozit elektrot, ultrasonikasyon ile eşleştirilmiş pulslu polimerizasyon tekniği ile hazırlanmıştır. Bu teknik, hem ultrasonikasyon hem de elektrokimyasal polimerizasyonun avantajlarına sahiptir. PPy-CNT kompoziti pulslu depolama tekniği ile camımsı karbon elektrot (GCE) yüzeyine kolayca modifiye edilmiş, ve metamizol yükseltgenmesine karşı camımsı karbon elektroda göre katalitik aktivitesi yüksek bir yüzey elde edilmiştir. Hazırlanan elektrot taramalı electron mikroskopu ile karakterize edilmiş ve pH:2 Britton-Robinson tamponunda metamizol davranışı incelenmiştir. Diferansiyel pulse voltammetrisi ile lineer aralık 5-500 mg L-1 olarak saptanmış ve belirtme alt sınırı1.6 mg L-1 olarak hesaplanmıştır. Yapılan tüm çalışmalar göstermiştir ki, PPY-CNT/GCE, metamizol tayini için yüksek duyarlılık, seçimlilik ve kararlılığa sahiptir. PPy-CNT/GCE sensörü novalgine tablet örneğine uygulanarak gerçek örnek analizi başarı ile gerçekleştirilmiştir.

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• ArticleYalnız künye2016/r/ebyu/21102
  All-Solid-State PVC Membrane Isoniazid-Selective Potentiometric Sensor

  Önder, Ahmet; Boz, Hakan; Çoldur, Fatih

  In this study; a potentiometric ion-selective electrode (ISE) was developed for the determination of isoniazid. Isoniazid-Tetraphenylborate ion-pair was synthesized and the synthesized ion pair was used as ionophore substance in electrode membrane structures. For the membrane optimization, PVC membrane ion selective electrodes in different compositions were produced by using the synthesized ion pair and their potentiometric performance characteristics were investigated. It was determined that the electrode membrane with the ratio of 3% izoniazid-tetraphenylborate ion pair, 67% nitrophenyloctylether and 30% PVC performed the best potentiometric performance characteristics. For this electrode, linear range, slope, detection limit, pH working range and response time were determined as 5.0&times;10-6-1.0&times;10-2 M, 41.2 mV/decade, 2.0&times;10-6 M, 1-4 and ? 30 s, respectively. By using the proposed electrode, isoniazid contents of the two different drug tablets, which is used in the treatment of tuberculosis, were determined. It was seen that the results obtained by the potentiometric technique were in good agreement with those of the results obtained by UV technique at 95% confidence level

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