Browsing by Author "Koyuncu, H"

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Adsorption of Benzoic Acid and Hydroquinone by Organically Modified Bentonites
(Elsevier Science Bv, 2005) Yildiz, N; Gönülsen, R; Koyuncu, H; Çalimli, A
Two organobentonites (ODTMA-B, HDTMA-B) were synthesized using hexadecyltrimethyle ammonium bromide (HDTMAB) and octadecyltrimethyle ammonium bromide (ODTMAB). Synthesized organobentonites were characterized by X-ray diffraction particle size, and surface area analysis. Particle size analyses of the original bentonite and organobentonites showed that the organobentonites contained a greater number of coarse particles than present in the original bentonite. While the basal spacings of the organobentonites increased organic cation, the surface area decreased. To evaluate the potential use of two modified bentonites in removing organic pollutants such as benzoic acid and hydroquinone from water, adsorption experiments were performed under conditions of varied pH (3, 6 and 11) and temperatures (298 and 313 K). Experimental results showed that the sorption capacities increase with decreasing pH value and increasing temperature. The adsorption equilibrium of benzoic acid and hydroquinone on organobentonites was described by the Langmuir and Dubinin-Radushkevich (D-R) models. It was concluded that the isotherm shapes were not affected by pH and temperature. Adsorption capacity of ODTMA-B for benzoic acid was higher compared to that of HDTMA-B at various pH and temperatures. (c) 2005 Elsevier B.V. All rights reserved.
Examination of Some Organic Explosives by Ion Mobility Spectrometry (Ims)
(Tubitak Scientific & Technological Research Council Turkey, 2005) Koyuncu, H; Seven, E; Çalimli, A
The increase in terrorist activities committed using explosives in recent years has generated the need for improved analytical methods that can accurately and quickly identify explosives and their residues. In this study such an analytical method is evaluated. In the first phase of the study, standard solutions and a standard mixture solution of TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitro-1,3,5-triazocyclohexane), PETN (pentaerythritoltetranitrate) and TETRYL (2,4,6-trinitrophenylmethylnitramine) were examined using ion mobility spectrometry (IMS). In the second phase, qualitative analysis of a real explosion residue was carried out and the explosive material used in the bomb was identified by analysing the acetone extract. In the third phase, a handswab sample taken from a suspect was analysed for trace explosive residues. Some advantages of using IMS for the detection of explosives and their residues were determined.
Traumatic Spinal Cord Injuries in Turkey
(Nature Publishing Group, 2000) Karacan, I; Koyuncu, H; Pekel, Ö; Sümbüloglu, G; Kirnap, M; Dursun, H; Tekeoglu, I
Study design: An epidemiological study conducted all over the country. Objective: The present retrospective study was conducted to survey the new traumatic spinal cord injury (SCI) cases during 1992 in Turkey. Setting: Intensive care units, emergency services and departments of orthopaedic surgery, neurosurgery and rehabilitation of state hospitals, rehabilitation centers: military and university hospitals. Methods: Postal questionnaires were used for data collection and the records from medical institutes nation-wide were reviewed for the analysis of the epidemiological factors. Results: Five hundred and eighty-one new traumatic SCI cases were reported in 1992. The annual incidence was found to be 12.7 per million population. Male to female ratio was 2.5 : 1 and the average age at injury was 35.5+/-15.1 (35.4+/-14.8 for males and 35.9+/-16.0 for females). The most common cause of injury was motor vehicle accidents (48.8%) followed by falls (36.5%), stab wounds (3.3%), gunshot injuries (1.9%) and injuries from diving (1.2%). One hundred and eighty-seven patients (32.18%) were tetraplegic and 394 patients (67.8%) were paraplegic. The most common level of injury was C5 among tetraplegics and T12 among paraplegics. The most prevalent associated injury was head trauma followed by extremity fractures. Severe head trauma resulting in death may obscure the real incidence of SCI and may cause underreporting of cases in epidemiological studies. Conclusion: Considering that motor vehicle accidents and falls were found to be the leading causes of traumatic SCI, it was concluded that the prevention measures should be focused mainly on these in order to reduce the frequency of SCI in Turkey.