Browsing by Subject "Scanning electron microscopy image"

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Open Access
Bacteria-immobilized electrospun fibrous polymeric webs for hexavalent chromium remediation in water
(Springer Berlin Heidelberg, 2016) Sarioglu, O.F.; Celebioglu A.; Tekinay, T.; Uyar, Tamer
The development of hexavalent chromium remediating fibrous biocomposite mats through the immobilization of a hexavalent chromium reducing bacterial strain, Morganella morganiiSTB5, on the surfaces of electrospun polystyrene and polysulfone webs is described. The bacteria-immobilized biocomposite webs have shown removal yields of 93.60 and 93.79 % for 10 mg/L, 99.47 and 90.78 % for 15 mg/L and 70.41 and 68.27 % for 25 mg/L of initial hexavalent chromium within 72 h, respectively, and could be reused for at least five cycles. Storage test results indicate that the biocomposite mats can be stored without losing their bioremoval capacities. Scanning electron microscopy images of the biocomposite webs demonstrate that biofilms of M. morganii STB5 adhere strongly to the fibrous polymeric surfaces and are retained after repeated cycles of use. Overall, the results suggest that reusable bacteria-immobilized fibrous biocomposite webs might be applicable for continuous hexavalent chromium remediation in water systems.
Open Access
Postdeposition annealing on RF-sputtered SrTiO3 thin films
(AVS Science and Technology Society, 2017) Bayrak, T.; Kizir,S.; Kahveci, E.; Bıyıklı, N.; Goldenberg, E.
Understanding of structural, optical, and electrical properties of thin films are very important for a reliable device performance. In the present work, the effect of postdeposition annealing on stoichiometric SrTiO3 (STO) thin films grown by radio frequency magnetron sputtering at room temperature on p-type Si (100) and quartz substrates were studied. Highly transparent and well adhered thin films were obtained in visible and near infrared regions. As-deposited films were amorphous, while nanocrystalline and polycrystalline phases of the STO thin films formed as a function of annealing temperature. Films annealed at 300 ï¿½C showed nanocrystallinity with some amorphous phase. Crystallization started after 15 min annealing at 700 ï¿½C, and further improved for films annealed at 800 ï¿½C. However, crystallinity reduced for films which were annealed at 900 ï¿½C. The optical and electrical properties of STO thin films affected by postdeposition annealing at 800 ï¿½C: Eg values decreased from 4.50 to 4.18 eV, n(λ) values (at 550 nm) increased from 1.81 to 2.16. The surface roughness increased with the annealing temperature due to the increased crystallite size, densification and following void formation which can be seen from the scanning electron microscopy images. The highest dielectric constants (46 at 100 kHz) observed for films annealed at 800 ï¿½C; however, it was lower for 300 ï¿½C annealed (25 at 100 kHz) and as-deposited (7 at 100 kHz) STO films having ∼80 nm thickness.