Browsing by Author "Gur, A."

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Adsorption of Aniline, Phenol, and Chlorophenols on Pure and Modified Bentonite
(Maik Nauka/interperiodica/springer, 2006) Yildiz, A.; Gur, A.; Ceylan, H.
In the present study, pure bentonite and bentonite modified by HNO 3, EDTA, and HDTMA are adsorbents. The changes on the surfaces of bentonite samples are studied by IR spectroscopy. The adsorption of aniline, phenol, and phenol derivatives on these adsorbents is examined by means of gas chromatography. As the result of these examinations, it is seen that the adsorption capacities of clay-organic complexes (bentonite - EDTA and bentonite-HDTMA) are higher than those of bentonite-HNO3 and pure bentonite.
Adsorption of Phenol and Chlorophenols on Pure and Modified Sepiolite
(Serbian Chemical Soc, 2007) Yildiz, A.; Gur, A.
In this work, pure sepiolite and sepiolite modified by nitric acid (HNO3), ethylenediaminetetraacetic acid (EDTA) and hexadecyltrimethylammonium (HDTMA) were used ad adsorbents. The changes on the surface were studied by IR spectroscopy, The adsorption of solutions of phenol and phenol derivatives in pure ethanol oil these adsorbents were examined by means of gas chromatography. It was found that the adsorption capacities of the clay-organic complexes (sepiolite-EDTA and sepiolite HDTMA) were higher than those of pure sepiolite and sepiolite-HNO3.
Adsorption of Phenol and Phenol Derivatives on Pure and Modified Kaolinite
(Mrs Pushpa Agarwal, 2006) Yildiz, A.; Gur, A.
In the present work, pure kaolinite and that modified by HNO3, EDTA and HDTMA, were used as the adsorbents. The changes on the surfaces were studied by IR spectroscopy. The adsorption of solutions of phenol and phenol derivatives in alcohol on these adsorbents was examined by means of gas-chromatography. As a result of these examinations, it was seen that the adsorption capacities of the clay-organic complexes (kaolinite-EDTA and kaolinite-HDTMA) were higher than pure kaolinite and kaolinite-HNO3.
An Autopsy Series: Lightning-Related Deaths in Van and Hakkari Provinces, Turkey
(Univ West indies Faculty Medical Sciences, 2021) Hekimoglu, Y.; Asirdizer, M.; Demir, U.; Gur, A.; Etli, Y.; Gumus, O.; Kartal, E.
Objective: To report the largest series of lightning-related deaths in Turkey, to review the literature on this subject, and to identify similarities and differences between the autopsy findings in this study and the information available in literature. Methods: In this study, autopsy reports and crime scene investigation data on 11 lightning-related fatalities that occurred in the Van and Hakkari Provinces, Turkey, from January 1, 2011 to December 31, 2015 were retrospectively reviewed. Results: Of the 1699 fatalities, 11 (2.53%) evaluated by medico-legal autopsy in the Van and Hakkari Province in a 5-year period died from lightning strikes. Of these cases, 10 (90.1%) were males and 1 (9.9%) was female (p < 0.05). All cases were in the 11 to 33 years age group. All cases were injured outdoors. Conclusion: We concluded that deaths due to lightning strikes are relatively rare in Turkey, and may be reduced with precautions such as avoiding staying under trees or in the vicinity of high towers, refraining from touching metal objects, avoiding lying on the ground, leaning on walls, and crouching outdoors.
The Comparison of Absorbed Dose Measurements for Water and Artificial Body Fluid
(Ijrr-iranian Journal Radiation Res, 2012) Cakir, T.; Gur, A.; Arasoglu, A.
Background: Advances in radiation dosimetry concepts and the development of primary measurement standards based on absorbed dose to water over the last decades offer the possibility to calibrate ionisation chambers directly in terms of absorbed dose to water. The aim of this study is the investigation on utility of artificial body fluid (ABF) instead of water by comparing dosimetric measurements for radiotherapy between water and ABF which is more close to human tissue. Materials and Methods: The measurements were done using Co-60 gamma source with a radiation field sizes of 5 x 5, 10 x 10, 15 x 15, 20 x 20 and 25 x 25 cm(2) at PTW Freiburg MP3 water phantom front surface. The comparisons of the dose measurements were obtained by using IAEA TRS-398 dosimetry protocols and Mephysto mc(2) dose analyzer program. Percent depth dose (PDD), dose profiles and penumbras are compared for water and ABF. Results: When the results of the PDD for water and ABF were compared, the maximum difference was observed in big field sizes. The difference in penumbras was found 2.3 mm averagely for depth of maximum dose (d(max)). In addition same differences were observed between water and ABF when the dose profiles were compared. It is found that PDD values taken for water are good agreed with PDD values published in British Journal of Radiology (BJR) Supplement 25. Conclusion: Since the ABF is more equivalent to human tissue than water, it is suggested that advanced dosimetric studies should be performed with ABF instead of water. Iran. J. Radiat. Res., 2012; 10(3-4): 157-164
Determination of Gamma and Fast Neutron Shielding Parameters of Magnetite Concretes
(Pergamon-elsevier Science Ltd, 2016) Oto, B.; Gur, A.; Kavaz, E.; Cakir, T.; Yaltay, N.
In this study, some gamma shielding parameters such as mass attenuation coefficient (mu(rho)), effective atomic number (Z(eff)), electron density (N-el) and buildup factors have been investigated for concretes with and without magnetite aggregate. The measurements have been carried out using 1.25 MeV (mean energy of 1.1732 MeV and 1.3325 MeV photons of a Co-60 radioactive source) gamma photons. The theoretical values of mu(rho) have been calculated in the energy range from 1 key to 100 GeV by WinXCom computer code and these values were used in order to calculate the values of Z(eff) and N-el. And fast neutron shielding parameter namely effective removal cross-sections (Sigma(R), cm(-1)) have been calculated. In addition, Energy absorption buildup factors (EABF) and exposure buildup factors (EBF) values of concrete samples have been calculated for photon energy 0.015-15 MeV up to 40 mfp (mean free path) penetration depths. The results of this study showed that the magnetite concrete is more efficient than the ordinary concrete for fast neutrons and gamma rays. (C) 2016 Elsevier Ltd. All rights reserved.
Dissolution Kinetics of Calcined Ulexite in Ammonium Chloride Solutions
(Mrs Pushpa Agarwal, 2006) Gur, A.; Yildiz, A.; Ceylan, H.
In this study, the leaching kinetics of calcined ulexite in ammonium chloride solutions were investigated. The effect of calcination temperature, solution concentration, reaction temperature and prehydration were chosen as parameters. It was observed that the rate of dissolution increased with increasing calcination temperature, solution concentration and reaction temperature, while it was not affected by prehydration. Employing graphical and statistical methods, the dissolution rate, based on homogeneous reaction model, can be shown as: (1 - X)(-1) - 1 = k(NH4Cl)(4/5). The activation energy for the dissolution of the ulexite sample calcined at 160 degrees C was found to be 62.65 kJ mol(-1).
Effects of Applied Electrical Field on Biochemical Parameters and Erythrocytes of Rats
(Mrs Pushpa Agarwal, 2006) Demir, H.; Cakir, T.; Karakaya, C.; Ilhan, A. Cebi; Onursal, N.; Gur, A.
The purpose of this study was to determine whether there was any effect of some biochemical parameters and erythrocyte carbonic anhydrase on electrical field stimulation in female rat. The experiments were performed under the animals' scientific procedures and conform to National Institute of Health guidelines for the use of experimental animals. This study was carried out on female Sprague-Dawley rats (250-270 g). Comparasons were made using student-t tests. A p value less than 0.001 was considered statistically significant. It was demonstrated that alanine aminotransferase, aspartate aminotransferase, amylase and lactate dehydrogenase in serum were significantly affected by this electric field stimulation (p < 0.001). In addition, particularly carbonic anhydrase activity was affected by applied electrical field.
Immobilization of Catalase Via Adsorption Into Natural and Modified Active Carbon Obtained From Walnut in Various Methods
(Academic Journals, 2009) Alkan, S.; Gur, A.; Ertan, M.; Savran, A.; Gur, T.; Genel, Y.
In the present work, the immobilization of catalase into natural active carbon and active carbon modified by hydrochloric acid was carried out. In the experimental section, the effects of pH, ionic strength and reaction temperature were chosen as parameters, with experiments performed in batch system. For the optimization of immobilization procedure, values of kinetic parameters were evaluated. It was observed that storage and operational stabilities of the enzyme increased with immobilization. The results obtained from experiments showed that active carbon is a valuable support for the adsorption of enzymes.
Immobilization of Catalase Via Adsorption Onto Natural and Modified Montmorillanit Analsim-Clay
(Polish Chemical Soc, 2009) Alkan, S.; Gur, T.; Gur, A.; Uruc, H.; Demir, H.
Immobilization of the enzyme catalase on natural and modified montmorillanit analsim-clays was investigated using a batch system. Such an immobilization does not result in enzyme inactivation and constitutes a valuable method for immobilizing catalase at high ionic strength. In the immobilization process, the effect of pH, ionic strength and reaction temperature were chosen as parameters. Furthermore the optimization of immobilization conditions were studied using data obtained from experimental results. For the free catalase and three different immobilized catalase enzymes, the optimum pH values 8, 7, 7 and 8; reaction temperature 30 degrees C; ionic strength 0.25 M were found. It was determined that enzyme activity for enzyme supported by natural clay was 73.3%, when it was retained during the storage at 4 degrees C for a period of 60 days. It was observed that storage and operational stabilities of the enzyme increased with immobilization. The results obtained show that montmorillanit analsim-clay is valuable and favourable support the simple adsorption of enzymes.
Immobilization of Polyphenol Oxidase Purified From Igdir Apricot on Bardakci-Clay
(2008) Demir, H.; Gur, A.; Yilidz, A.; Gur, T.
It is known that immobilized enzymes more useful and advantageous than free enzymes. In this work, polyphenol oxidase purifed by affinity chromatography from lgdir apricot was immobilized onto natural bardakci-clay by physical adsorption method. The properties of the immobilized enzyme were compared to the tree enzyme. The PPO activity of immobilized clay was determined, and then the effects of reaction optimum temperature, thermostability, optimum pH, ionic effect and kinetic parameters were investigated. Catechol was used as substrate, the activities of immobilized and free polyphenol oxidase were determined in the reaction mixture containing substrate catechol. The results obtained from experiments indicated that physical adsorption is favourable for attachment of enzyme onto bardakci-clay.
Investigations of the Inhibition Kinetics of Some Drugs and Chemicals on Enzyme of Polyphenol Oxidase Purified From Apricot's (Salak)
(2007) Cimen, C.; Demir, H.; Gur, A.; Kubilay, S.
Polyphenol oxidase (PPO) was purified from Igdir apricot, with a 367 fold purification of PPO by affinity chromatography being achieved. Amount of the protein was determined according to Bradford method. Vmax and Km values were found by means of Lineweaver- Burk graphs. Asetly salisilic acid, paracetamol, ascorbic acid (vitamin C), sodium sulphate, copper sulphate, glucose, sodium nitrite, sodium chlorure, glisine, sodium azide, 2-merkaptoethanol, tyrosine, citric acid, etilendiamin tetra acetic acid (EDTA) ve p-amino benzoic acid were used as inhibitor. Inhibition constants Ki of each inhibitor were found from Lineweaver-Burk graphs. It was found that the p-aminobenzoik acid function showed the highest inhibitory effect.
Studies on Dissolution Mechanism of Ulexite in Sulphuric Acid
(Asian Journal of Chemistry, 2007) Gur, A.; Selcuk, A.
There is the largest fraction of the world's boron reserves in Turkey. Ulexite, which is one of the most widely available boron minerals, has the chemical formula Na2O center dot 2CaO center dot 5B(2)O(3)center dot 16H(2)O and triclinic crystal structure and is used usually in the production of boric acid. The present study concerns an investigation of the dissolution mechanism of ulexite in H2SO4 solution for high solid to liquid ratios and the effect of acid concentration, the effect of SO42- on the dissolution process, using H2SO4, HCl + H2SO4 and H2SO4 + Na2SO4 solutions. The analysis of the experimental data show that increasing SO42- concentration reduced dissolution rate because of the precipitation of a solid film of CaSO4 and CaSO2 center dot H2O, but increasing H3O+ acid concentration increased the dissolution rate.