Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2A New Fluorescent 'turn On' Probe for Rapid Detection of Biothiols(Taylor and Francis Ltd., 2020) Üçüncü, Muhammed; Zeybek, Hüseyin; Karakuş, Erman; Üçüncü, Canan; Emrullahoğlu, MustafaWe designed and synthesised a novel molecular probe exhibiting high selectivity and sensitivity towards reactive sulphur species (RSS) over other amino acids and biologically relevant species, as well as scrutinised its spectroscopic behaviours under physiological conditions and in living milieu. We used an electrophilic cyanate group as a masking agent to block the excited state intramolecular proton transfer process of 2-(2-cyanato-3-methoxyphenyl)benzo[d]thiazole (HMBT-OCN), which readily hydrolyses to the highly fluorescent structure, 2-(2'-Hydroxy-3'-methoxyphenyl) benzothiazole (HMBT-OH), in the presence of reactive sulphur species. [GRAPHICS] .Article Citation - WoS: 2Citation - Scopus: 3Determination of Arsenic by Hydride Generation—laser-Induced Breakdown Spectroscopy: Characterization of Interelement Interferences(Taylor and Francis Ltd., 2018) Bölek, Deniz; Ünal Yeşiller, Semira; Yalçın, ŞerifeIn this study, interelement interferences were evaluated for the determination of arsenic in aqueous samples through laser-induced breakdown spectroscopy (LIBS) hyphenated with a hydride generation sample introduction system. Optimum instrumental and chemical parameters were selected and variation in LIBS signal intensity was recorded for As solution in the presence of comparable concentrations of interfering elements. No significant change in the signal intensity of As(I) 228.8 nm line was observed in the presence of alkali/alkali earth metals; however, the presence of hydride-forming elements has shown a noticeable decrease in the line emission strength of arsenic. The least variation in arsenic signal was observed in the presence of Ge, the most volatile of all. However, the signal has decreased to a greater extent in the presence of Sn, Sb, and Pb. The presence of interfering elements on electron temperature and electron number density of arsenic plasma has also been studied. Plasma temperatures calculated using both As and Ar emission lines in the Boltzmann equation were similar, being around 5000 K. The McWhirter criterion for stationary and homogenous plasmas was utilized for the establishment of the local thermodynamic equilibrium under the plasma conditions studied. Applicability of the technique for multielemental analysis of water samples was tested through spiking experiments. Arsenic signal showed 26% decrease in the multielemental mixture solution. LIBS is among a few atomic spectroscopic techniques that facilitate rapid and simultaneous multielemental analysis without extensive sample preparation steps. However, the analytical performance of the technique still requires more serious efforts to compete with other conventional techniques for routine analysis of environmental samples.Article Citation - WoS: 12Citation - Scopus: 13History of Spectroscopy and Modern Micromachined Disposable Si Atr-Ir Spectroscopy(Taylor and Francis Ltd., 2018) Koç, Mert; Karabudak, EnginIn this article, the historical development of spectroscopy is examined and the spectroscopy devices used today are described. Then, we focus on infrared (IR) spectroscopy, which cannot give valuable signal in aqueous solution. Attenuated total reflection (ATR)-IR technique solves the problem. In addition, we specifically mention newly developed disposable ATR-IR crystals and micromachined silicon (Si) ATR-IR. Disposable crystal systems and microfluidics systems can be integrated with existing miniature ATR analyzers. If the integration is successful, the technique might be used in biomedical measuring instruments, reactions' analyses, and ultra-high-pressure analyses.Article Citation - WoS: 19Citation - Scopus: 24Geographical Origin of Imported and Domestic Teas (camellia Sinensis) From Turkey as Determined by Stable Isotope Signatures(Taylor and Francis Ltd., 2017) Cengiz, Mehmet Fatih; Turan, Önder; Özdemir, Durmuş; Albayrak, Yalçın; Perinçek, Fatih; Kocabaş, HalilIn this study, stable isotope signatures (δ13C, δ15N, and δD) of both tea leaves and tea infusions were investigated to identify the geographical origin of Turkish domestic and imported tea samples. Sixteen domestic tea samples collected from different locations in the Black Sea Region, which produces almost 100% of tea in Turkey, and 11 imported tea samples (Kenya, India, Sri Lanka, Indonesia, and China) purchased from importers were studied. δ13C, δ15N, and δD in the samples were determined using isotope ratio mass spectrometry (IR-MS). δ13C in the samples ranged from −29.18 ± 0.01 to −25.7 ± 0.2, while δ15N ranged between 1.1 ± 0.2 and 5.2 ± 0.8. However, δD in the samples were found to be in the range from 56.5 ± 0.3 to 72 ± 1. The classifications of the tea samples into domestic and imported tea samples were achieved with 100% accuracy using multivariate statistical analyses (principal component analysis, PCA, and hierarchical cluster analysis, HCA). In conclusion, the domestic tea samples had a distinctive isotopic fingerprint and the isotopic ratios used in the study can be significant predictors in determination of the geographical source of Turkish tea.Article Citation - WoS: 15Citation - Scopus: 15Bodipy-Conjugated Chitosan Nanoparticles as a Fluorescent Probe(Taylor and Francis Ltd., 2017) Bor, Gizem; Üçüncü, Muhammed; Emrullahoğlu, Mustafa; Tomak, Aysel; Şanlı Mohamed, GülşahRecently, development of fluorescent nanoparticle-based probes for various bioimaging applications has attracted great attention. This work aims to develop a new type fluorescent nanoparticle conjugate and evaluate its cytotoxic effects on A549 and BEAS 2B cell lines. Throughout the study, ionically crosslinked chitosan nanoparticles (CNs) were conjugated with carboxylated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY-COOH). The results of conjugates (BODIPY-CNs) were investigated with regard to their physic-chemical, optical, cytotoxic properties and cellular internalization. The morphology of BODIPY-CNs was found to be spherical in shape and quite uniform having average diameter of 70.25 ± 11.99 nm. Cytotoxicty studies indicated that although BODIPY-COOH itself was quite toxic on both A549- and BEAS 2B-treated cells, CNs increased the cell viability of both cell lines via conjugation to BODIPY-COOH fluorescent molecule up to 67% for A549 and 74% for BEAS 2B cells. These results may suggest a possible utilization of the new fluorescent nanoparticle-based probe for bioimaging in biology and medicine.Article Citation - WoS: 4Citation - Scopus: 5Characterization of a Novel Dioxomolybdenum Complex by Cyclic Voltammetry(Taylor and Francis Ltd., 2015) Knittl, Esther Theresa; Rusakov, D. A.; Korotkova, E. I.; Dorozhko, E. V.; Voronova, O. A.; Plotnikov, E. V.; Topaloğlu Sözüer, Işıl; Linert, WolfgangMetalloenzymes that carry a pterin-based molybdenum cofactor in their center catalyze numerous reactions in the human body and play a crucial role in its metabolism. Specifically, these enzymes promote redox reactions and oxygen transport in the body. Their absence may cause many problems leading to disability or even death in early childhood. Therefore, model compounds need to be synthesized and analyzed to investigate the reactivity, redox potential, and geometry of these cofactors. This study focused on electrode processes and determined the redox potentials of the new bis-(4-mercapto-5-(p-tolyl)-3H-1,2-dithiole-3-thione)-dioxomolybdenum complex by cyclic voltammetry. The 4-mercapto-5-(p-tolyl)-3H-1,2-dithiole-3-thione ligand underwent irreversible oxidation and reduction at thiol and thione functional groups. The new dioxomolybdenum complex showed a quasi-reversible two-stage electrode process.Article Citation - WoS: 15Citation - Scopus: 21Preparation, Characterization and Optimization of Chitosan Nanoparticles as Carrier for Immobilization of Thermophilic Recombinant Esterase(Taylor and Francis Ltd., 2011) İlgü, Hüseyin; Turan, Taylan; Şanlı Mohamed, GülşahImmobilization of biologically important molecules on myriad nano-sized materials has attracted great attention. Through this study, thermophilic esterase enzyme was obtained using recombinant DNA technology and purified applying one-step His-Select HF nickel affinity gel. The synthesis of chitosan was achieved from chitin by deacetylation process and degree of deacetylation was calculated as 89% by elemental analysis. Chitosan nanoparticles were prepared based on the ionic gelation of chitosan with tripolyphosphate anions. The physicochemical properties of the chitosan and chitosan nanoparticles were determined by several methods including SEM (Scanning Electron Microscopy), FT-IR (Fourier Transform Infrared Spectroscopy) and DLS (Dynamic Light Scattering). The morphology of chitosan nanoparticles was spherical and the nanospheres' average diameter was 75.3 nm. The purified recombinant esterase was immobilized efficiently by physical adsorption onto chitosan nanoparticles and effects of various immobilization conditions were investigated in details to develope highly cost-effective esterase as a biocatalyst to be utilized in biotechnological purposes. The optimal conditions of immobilization were determined as follows; 1.0 mg/mL of recombinant esterase was immobilized on 1.5 mg chitosan nanoparticles for 30 min at 60C, pH 7.0 under 100 rpm stirring speed. Under optimized conditions, immobilized recombinant esterase activity yield was 88.5%. The physicochemical characterization of enzyme immobilized chitosan nanoparticles was analyzed by SEM, FT-IR and AFM (Atomic Force Microscopy).Article Citation - WoS: 21Citation - Scopus: 23Adsorption of Methylene Blue From Aqueous Solution on High Lime Fly Ash: Kinetic, Equilibrium, and Thermodynamic Studies(Taylor and Francis Ltd., 2012) Keleşoğlu, Serkan; Kes, Mürşide; Sütçü, Leman; Polat, HürriyetKinetic, equilibrium, and thermodynamic studies were performed for the batch adsorption of methylene blue (MB) on the high lime fly ash as a low cost adsorbent material. The studied operating variables were adsorbent amount, contact time, dye concentration, and temperature. The kinetic data were analyzed using the pseudo-first order and pseudo-second order kinetic models and the adsorption kinetic was followed well by the pseudo-second order kinetic model. The equilibrium data were fitted with the Freundlich, Langmuir, and Dubinin Radushkevich (D-R) isotherms and the equilibrium data were found to be well represented by the Freundlich and D-R isotherms. Based on these two isotherms MB is taken by chemical ion exchange and active sites on the high lime fly ash have different affinities to MB molecules. Various thermodynamic parameters such as enthalpy of adsorption (ΔH°), free energy change (ΔG°), and entropy change (ΔS°) were investigated. The positive value of ΔH° and negative value of ΔG° indicate that the adsorption is endothermic and spontaneous. The positive value of ΔS° shows the increased randomness at the solid-liquid interface during the adsorption. A single-stage batch adsorber was also designed based on the Freundlich isotherm for the removal of MB by the high lime fly ash. © 2012 Copyright Taylor and Francis Group, LLC.Article Citation - WoS: 18Citation - Scopus: 22Prediction of Lignin and Extractive Content of Pinus Nigra Arnold. Var. Pallasiana Tree Using Near Infrared Spectroscopy and Multivariate Calibration(Taylor and Francis Ltd., 2009) Üner, Birol; Karaman, İbrahim; Tanrıverdi, H.; Özdemir, DurmuşDetermination of quality parameters such as lignin and extractive content of wood samples by wet chemistry analyses takes a long time. Near infrared (NIR) spectroscopy coupled with multivariate calibration offers a fast and nondestructive alternative to obtain reliable results. However, due to the complexity of the spectra obtained from NIR, some wavelength selection is generally required to improve the predictive ability of multivariate calibration methods. Pinus nigra Arnold. Var. pallasiana is the second most growing pine species in Turkey. Even though its rotation period is very high, around 120 years, the forest products industry has widely accepted the use of Pinus nigra because of its ability to grow on a wide range of sites and its suitability to produce desirable products. In this study, 51 samples of Pinus nigra trees were collected and their lignin and extractive content were determined with standard reference (TAPPI) methods. Then, the same samples were scanned with near infrared spectrometer between 1000 and 2500 nm in diffuse reflectance mode. Multivariate calibration models were built with genetic inverse least squares method for both lignin and extractive content using the concentration information obtained from wet standard reference method. Overall, standard error of calibration (SEC) and standard error of prediction (SEP) were ranged between 0.35% (w/w) and 2.4% (w/w).Article Citation - WoS: 11Citation - Scopus: 13Near Infrared Spectroscopic Determination of Diesel Fuel Parameters Using Genetic Multivariate Calibration(Taylor and Francis Ltd., 2008) Özdemir, DurmuşThe use of full spectral region from near infrared spectroscopic analysis does not always end up with a good multivariate calibration model as many of the wavelengths do not contain necessary information. Due to the complexity of the spectra, some of the wavelengths or regions may, in fact, disturb the model-building step. Genetic algorithms are one of the useful tools for solving wavelength selection problems and may improve the predictive ability of conventional multivariate calibration methods. This study demonstrates application of genetic algorithm-based multivariate calibration to near infrared spectroscopic determination of several diesel fuel parameters. The parameters studied are cetane number, boiling and freezing point, total aromatic content, viscosity, and density. Multivariate calibration models were generated using genetic inverse least squares (GILS) method and used to predict the diesel fuel parameters based on their near infrared spectra. For each property, a different data set was used and in all cases the number of samples was around 250. Overall, percent standard error of prediction (%SEP) values ranged between 2.48 and 4.84% for boiling point, total aromatics, viscosity, and density. However, %SEP results for cetane number and freezing point were 11.00% and 14.86%, respectively.