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    Investigation of coagulation and electrokinetic behaviors of clinoptilolite suspension with multivalent cations
    (TAYLOR & FRANCIS INC, 2018) Ozkan, A.; Sener, A. G.; Ucbeyiay, H.
    This paper presents the results of investigations concerning the influence of magnesium, copper, aluminum and ferric cations on the coagulation and electrokinetic behaviors of clinoptilolite suspension. While clinoptilolite exhibited a negative surface charge over a broad pH range and had no isoelectric point (iep), especially the trivalent ions strongly changed the sign and magnitude of the zeta potential of the mineral depending on pH and cation concentration. The coagulation of clinoptilolite particles with these metal cations also showed sharp dependences on pH and cation concentration. That is, the coagulation process significantly took place in the pH and concentration ranges in which metal hydroxides existed in the suspension. Moreover, the coagulation behavior of clinoptilolite at pH values below the iep of metal hydroxides was usually consistent with its zeta potential variation, indicating a coagulation process by the charge neutralization mechanism. However, at pH values larger than the iep of these hydroxides, sweep coagulation of clinoptilolite suspension occurred and a clear correlation between surface charge and the onset of coagulation was not determined.
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    Molecular Epidemiology of Vancomycin-resistant Enterococcus Faecium Strains Isolated from Haematological Malignancy Patients in a Research Hospital in Turkey
    (SOC GENERAL MICROBIOLOGY, 2010) Kırdar, S.; Sener, A. G.; Arslan, U.; Yurtsever, S. G.
    Infections and outbreaks of vancomycin-resistant enterococci (VRE) still appear to be rare in Turkey In the present study. VRE strains isolated during an outbreak in a haematology unit of a training and research hospital in Turkey were typed and their antimicrobial-resistance patterns were characterized by molecular methods Twelve vancomycin-resistant Enterococcus faeciurn strains isolated from patients with haematological malignancies were investigated by PCR for the presence of genes encoding resistance to vancomycin. tetracycline, chloramphenicol, gentamicin and erythromycin Their clonal relationship was evaluated by PFGE and multilocus sequence typing. All strains were resistant to vancomycin and erythromycin, and had the vanA and ermB genes, respectively. PFGE was used to determine the presence of two pulsotypes and determine their subtypes. Pulsotype A belonged to sequence type (ST) 17 and pulsotype B belonged to ST 78. All strains with the vanA gene were not the same clone, indicating multiple acquisitions of resistant isolates, even over such a short time period.