Kursun I.,Istanbul UniversityIstanbul |
Terzi M.,Istanbul UniversityIstanbul
Mineral Processing and Extractive Metallurgy Review | Year: 2016
Coal combustion results in wastes such as fly ash, slag, and flue gases. In Turkey, approximately 45 million tons of coals are fired annually and consequently around 20 million tons of fly ashes are produced. Such large volumes of ash pose a significant problem both for society and the environment. Furthermore, significant amounts of uranium and thorium are often encountered in these ashes. These concentrations are relatively higher for ashes from younger age lignites. Within the scope of this study, a series of characterization tests were performed on samples taken from Soma thermal power plant, one of the largest in Turkey. Characterization studies include particle size analysis, moisture analysis, density determination, pH profile measurements, chemical analyses, and mineralogical analyses. Leach tests with sulfuric acid (H2SO4) were then performed. The leaching of the radioactive minerals (uranium and thorium) with the help of sulfuric acid in the ashes was examined and the optimum leaching parameters were investigated. The recovery opportunities of uranium and thorium metals in the ashes were addressed. The results indicated that under optimum conditions, 94.71% uranium dissolution efficiency and 93.21% thorium dissolution efficiency were obtained. © 2016 Taylor & Francis.
Kimiran-Erdem A.,Istanbul University |
Arslan-Aydogdu E.O.,Istanbul University |
Gurun S.,Istanbul UniversityIstanbul |
Altun O.,Istanbul University
Polish Journal of Environmental Studies | Year: 2015
One hundred strains of Gram-negative bacteria were isolated from a brackish water Lagoon, Kucukcekmece in Istanbul-Turkey. Identification studies showed that 31% of the isolated bacteria were Escherichia coli, 28% were Citrobacter, and 12% were Enterobacter. Antibiotic and heavy metal resistances exhibited by these bacteria were evaluated. In antibiotic susceptibility tests, 68% of the isolates appeared to be resistant to vancomycin, while 38% was resistant to erythromycin, 23% to penicilin G, 19% to ampicillin, 13% to nalidixic acid and streptomycin, 7% to chloramphenicol, 5% to amikacin, 2% to gentamycin, and 1% to kanamycin. Most of the isolates tolerated various concentrations of heavy metals, and the minimum inhibitory concentrations (MIC) ranged from 20 μg/ml to >5000 μg/ml. In terms of heavy metal sensitivity, 98% of the isolates were resistant to Fe, 95% to Cd, 85% to Co, 83% to Cu and Zn, and 74% to Ni. When antibioticheavy metals multiresistance index was examined, it was determined that the multiple heavy metal resistance (MHMR) index was remarkably high for the bacteria, while the multiple antibiotic resistance (MAR) index was low according to heavy metal resistance. It was demonstrated that the bacteria isolated from Kucukcekmece Lagoon were highly resistant to antibiotics and heavy metals. It was concluded that if the wastewater discharge to the Lagoon is not regulated, resistance gene transfers into the bacteria hosted normally in human microbiota could create significant health issues. © 2015, Pol. J. Environ. Stud. All rights reserved.
Senol A.,Istanbul UniversityIstanbul
Separation Science and Technology (Philadelphia) | Year: 2015
Data for the extraction of chromium(VI) from aqueous sulfate solutions by Alamine 300/Aliquat 336 and di–n–octyl amine/tributyl phosphate (DOA/TBP) have been subjected to formulation of an optimization structure for an effective Cr(VI) separation based on the derivative variation method. Both experimentally and analytically defined optimum Cr(VI) removal efficiencies are ranging about 83–99%, 71–93%, and 60–73% for Alamine 300/Aliquat 336, DOA/TBP, and DOA, respectively. Modeling efforts based on mass-action law methodology and non-homogeneous differential approach have shown considerable success yielding a 10% mean error, and satisfies established limiting behavior of the physical event. © , Copyright © Taylor & Francis Group, LLC.
Sen S.,Istanbul UniversityIstanbul |
Ufuktepe B.,Istanbul UniversityIstanbul |
Ozunal Z.G.,Istanbul UniversityIstanbul |
Uresin Y.,Istanbul UniversityIstanbul
EXCLI Journal | Year: 2014
The coexistence of hypertension and diabetes increases the incidence of cardiovascular events and long-term morbidity and mortality. Blood pressure should be controlled with the most appropriate drugs as well as tight blood glucose control in patients with diabetes and hypertension. RAAS (Renin Angiotensin Aldosterone System) blockers have an important role in the treatment of these patients, in this sense, ACEi and ARB remained the major treatment option in hypertension guidelines. The most recent RAAS blocker to be approved by the FDA was aliskiren in 2007, a renin inhibitor. Studies showed that aliskiren is as effective as other antihypertensive drugs and has a safety profile similar to placebo. The potent renin inhibitor aliskiren directly inhibits the RAAS system at its rate limiting step and differently from other RAAS blockers; it decreases plasma renin activity (PRA). Although the relationship of increased PRA levels and cardiovascular risk has been shown, it is unclear if the PRA decrease provided by aliskiren has an impact on clinical outcomes and cardiovascular endpoints. On the other hand, large trials like ASPIRE, AVANT-GARDE, ALTITUDE, ASTRONAUT, which investigated the combination of aliskiren with other RAAS blockers, failed to show the expected outcomes or resulted with an increased incidence of adverse effects, which raised more questions. As a result of the ALTITUDE trial, combination of aliskiren with an ACEi or ARB is not recommended in patients with hypertension and diabetes, or at least moderate renal dysfunction. Trials designed to prove aliskiren’s efficacy in new indications like diabetes, may face similar problems related to dual RAAS blockade because in the majority of cases, the optimal treatment is achieved with an ACEi or ARB. In this conjuncture, the increase in adverse events seen with aliskiren might be related to dual RAAS blockade rather than aliskiren directly. For instance, it is unclear whether the adverse event incidence would be the same, less, or higher if ALTITUDE was designed to investigate ACEi and ARB combination without aliskiren. In fact, every new molecular entity and mechanism of action faces the same barriers. For the time being, differentiating points like PRA lowering effects as an add-on therapy to calcium channel blockers or hydrochlorothiazide, and the populations that might have additional benefit, should be carefully investigated. © 2014, Leibniz Research Centre for Working Environment and Human Factors. All rights Reserved.