Browsing by Author "Gokkus K."

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Amine functionalized poly (glycidyl methacrylate) hydrogels for Congo red adsorption
(2023-01-01) Gokkus K.; Sengel S.B.; Yildirim Y.; Hasanbeyoglu S.; Butun V.
Assessment of heavy metal levels in tissues of common guitarfish (Rhinobatosrhinobatos) from Iskenderun and Antalya Bays, Northeastern Mediterranean sea
(2016-11-01) Gokkus K.; Turkmen M.
According to dry weight basis analysis, the lowest heavy metal level was generally detected in the muscle and the highest amount was determined in the intestine in both bays. Although the results of Iskenderun bay were higher than Antalya bay. When the heavy metal levels in the muscle are compared with the national and international standards, it was indicated that the metal concentrations were below the permissible limits. From this aspect, Iskenderun and Antalya bays do not contain adequate amounts of heavy metal to cause pollution.
Characterization of Divalent Metal Soaps of Cannabis Sativa Seed Oil
(Gazi Üniversitesi, 2023-09-01) Yetgin S.; Egbuchunam T.; Okieimen F.; Gokkus K.; Guney K.
n this study, the structural characteristics and thermal degradation behaviour of barium, calcium and zinc soaps of hemp seed oil prepared using the metathesis method are reported. Scanning electron micrographs of the metal soaps showed similar plate-like microstructures and are indicative of an orderly packed particulate structure. The bands at 1509, 1539 and 1543 cm-1 in the FTIR spectra showed the association of the carboxylate ion with Ba, Ca and Zn ions respectively The thermal decomposition consisted of one single step on the weight loss – temperature curves located around 250 – 450oC for all the divalent metal soaps at the various heating rates and the observed loss in weight which occurred before 200oC was minimal (< 10%). The average values of the apparent activation energy for the thermal process were 18.73, 13.77 and 8.48 kJ/mol for Zn-HSO, Ca-HSO and Ba-HSO respectively.
Effect of dietary protein level on growth performance and nitrogen excretion of the juvenile convict cichlid, Amatitlania nigrofasciata
(2014-01-01) Gultepe N.; Acar U.; Kesbic O.; Gokkus K.; Aydin S.
A 8 weeks growth trial was conducted to determine the effects of dietary protein on the growth of the convict cichlid Amatitlania nigrofasciata and on water quality in closed recirculating systems. Four test diets were formulated to contain protein levels ranging 30-45%. The fish averaging 0.47±0.07 g were reared in 10 L aquarium. Fish were fed ad libitum at 08:30, 12:30 and 16:30 for 8 weeks. A second-order polynomial regression between dietary protein levels and weight gain in each group, demonstrated that the most suitable protein level for maximum growth was determined to be 40.8%. The feed conversion ratios of fish ranged from 1.78-2.78 in the experimental groups. Results showed significant differences in SGR and WG. Dietary protein level significantly influenced ammonia excretion, fish fed 45% protein excreted higher concentrations of ammonia-nitrogen than fish fed 30-40% dietary protein. For optimum growth, feed conversion and ammonia excretion, a diet containing 40.8% protein, 12% lipid and 20.8 kJ gross energy/kg diet is recommended for juvenile convict cichlids, A. nigrofasciata. © Medwell Journals, 2014.
Heavy metal pollution in Inebolu and Bartin Ports, Black Sea, Turkey
(2019-01-01) Gokkus K.; Berber S.
The study was conducted in Inebolu and Bartin ports located in Black Sea region of Turkey between August 2013 and July 2014. Sea water, sediment, and Mytilus galloprovincialis samples were collected from both ports and the amounts of 11 heavy metals (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in each sample were determined. When the results for sediment samples were compared with the limit values of US EPA, it was found that the port of Bartin was very polluted in terms of Ni, and moderately polluted in terms of Cr and Cu, while the port of Inebolu was very polluted in terms of Cu and moderately polluted in terms of Cr and Ni. Pollution was found in sea water in both ports. When the data of Mytilus galloprovincialis was compared with the meat quality standards of European Commission (EU), it was determined that As, Cd, Cu, and Zn values were high in Inebolu post and As, Cd, and Zn values were high in Bartin port. It was observed that the load diversity, ships, shipyard, submarine maintenance and repair facility, runoffs and rivers and port activities were responsible for the pollution.
Synthesis and characterization of azo cross-linked polymer as a new catalyst for the production of hydrogen gas by methanolysis of NaBH4
(2024-10-20) Gokkus K.; Gür M.; Bütün V.