2,286 research outputs found
Greybody Factors of Holographic Superconductors with Lifshitz Scaling
We study the quasinormal modes and thermal radiation of massless spin-0 field
perturbations in the background of four-dimensional (4D) non-Abelian charged
Lifshitz black branes with hyperscaling violation, which correspond to
systems with superconducting fluctuations. After having an analytical solution
to the Klein-Gordon equation, we obtain exact quasinormal modes that are purely
imaginary. Therefore, there is no oscillatory behavior in the perturbations
that guarantees the mode stability of these solutions. We also study the
greybody factors, absorption cross-section, and decay rate of the non-Abelian
charged Lifshitz black branes. We derive their analytical expressions and then
investigate the correspondence in the strongly coupled dual theory. This study
might shed light on the mechanism governing the high-temperature
superconductors in condensed matter physics.Comment: 23 pages; Published in "The European Physical Journal C"
(Springer-Nature
Synthesis and characterization of novel graft copolymers by radiation induced grafting
The radiation-induced graft copolymerization of N-vinyl-2-pyrrolidone (NVP), 4-vinyl pyridine (4VP), 2-vinyl pyridine (2VP) monomers onto poly (ethylene-alt-tetrafluoroethylene) (ETFE) was investigated. The influence of synthesis conditions particularly the solvent was studied. Various solvents, such as n-propanol, isoproponol, benzyl alcohol, methanol, ethanol, cyclohexanone, tetrahydrofuran (THF), nitromethane, 1,4-dioxane and n-heptane were examined for this purpose. Graft copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical analysis (DMA), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDAX). It was found that the nature of the solvent had profound influence over the grafting reaction. Cyclohexanone, n-propanol and isoproponol for 4VP/ETFE grafting, THF and 1,4-dioxane for NVP/ETFE grafting and benzyl alcohol and methanol for 2VP/ETFE grafting were found to be the suitable solvents yielding highest graft levels. Isoproponol and n-propanol are promising in terms of both graft level and mechanical properties for 4VP/ETFE. Grafting of NVP, 4VP and 2VP onto ETFE were verified through FTIR spectroscopy. Storage modulus and glass transition temperature of the copolymers were found to increase as graft level increased. Surface profile of representative films was also investigated by viewing the distribution of elemental nitrogen using SEM-EDAX. Results indicated that copolymers of 4VP, NVP and 2VP are considerably different from each other. 4VP based copolymers exhibited relatively more homogenous grafting over the surface compared to NVP and 2VP based copolymers
Görkemli bir İstanbul kitabı
Taha Toros Arşivi, Dosya Adı: İstanbul Genel Dökümanlarıİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
Paris't bir kahveye Yahya Kemal plaketi konuldu
Taha Toros Arşivi, Dosya No: 182-Yahya Kemal Beyatlıİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
Fransa'da Nazım Hikmet
Taha Toros Arşivi, Dosya Adı: Nazım Hikmetİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
Facile synthesis of polypyrrole/graphene nanosheet-based nanocomposites as catalyst support for fuel cells
The integration of catalyst metals into the graphene-based composites can be a new way to ensure thermal and electronic conductivities of the catalyst support materials in polymer electrolyte membrane fuel cells. In this work, graphene nanosheets were synthesized via a mild and safer chemical route including three major steps: graphite oxidation, ultrasonic treatment and chemical reduction. Then, polypyrrole was coated on graphene nanosheets by in-situ polymerization to fabricate polypyrrole/graphene nanosheet-based nanocomposites as the catalyst supports. Pt nanoparticles were uniformly dispersed on the surface of nanocomposites by sonication technique
Benim Adım Kırmızı
Taha Toros Arşivi, Dosya No: 12-Orhan Pamu
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