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The effects of variable air flow rates for the system performance on the thermoelectrical modulled water cooler
(e-Journal of New World Sciences Academy, Technological Applied Sciences, 2010) Yavuz, Celil; Özkaymak, Mehmet; Kaya, Metin
Bu çalışmada, 1.5 litre hacmindeki hazne içerisine doldurulan 1 kg su, 40 x 40 x 3.8 mm boyutunda TEC–12706 kodlu termoelektrik modül vasıtasıyla soğutulmuştur. Modülün diğer yüzeyindeki kanatçıkları üç farklı hava debisi ile soğutularak sistem performansına etkisi incelenmiştir. Yüksek hava debisi, modülün performansını arttırmasına rağmen daha fazla fan gücü harcanmasına neden olduğundan sistemin toplam performansını düşürmektedir.
Theoretical Study of Vibrational Frequencies and Chemical Shifts of Choline Halides (F, Cl, Br)
(SDU Journal of Science (E-Journal), 2010) Karakaya, Mustafa; Ucun, Fatih; Tokatlı, Ahmet; Bahçeli, Semiha
The vibrational frequencies and 1H and 13C chemical shifts of choline halides have been calculated using density functional theory (B3LYP) method with 6-311++G(d, p) and 6-31 G(d, p) basis set level in Gaussian 03 and Parallel Quantum Solutions (PQS) ab initio packages programs, respectively. The calculated optimized geometric parameters, vibrational frequencies and chemical shifts were seen to be a very good agreement with the experimental data. The electronegativity influence of the halogen substitutions on the vibrational frequencies and chemical shifts have also been investigated. It was observed that the chemical shifts for H nucleus, especially the most near nucleus to the halogen atom decrease while it increases for C nucleus. The roughly linear variation of the chemical shift with the electronegativity of the halogen, whatever the shielding for C nucleus or deshielding for H nucleus is, has been commented that the local electron density near the halogen atom is affected.
Bloch-Gruneisen Fonksiyonu ile Bazı Katıların Elektriksel Özdirencinin Sıcaklığa Göre Değişiminin Analitik İncelenmesi
(SDU Journal of Science (E-Journal), 2013) Karakaya, Mustafa; Askeroğlu, İskender
Bu çalışmada, binomial açılım teoremi kullanılarak Bloch-Gruneisen fonksiyonunun analitik ifadeleri ile bazı katıların özdirencinin sıcaklığa bağlılığı incelendi. Bu yöntemde, metallerin elektriksel özdirencine elektron-fonon etkileşim katkısı dikkate alındı. Bu sebeple, özdirencin sıcaklığa göre değişmesinin Bloch-Gruneisen fonksiyonları ile analizine yer verildi. Genelleştirilmiş Bloch-Gruneisen fonksiyonu için elde edilen analitik bağıntılar doğrultusunda Mathematica programlama dilinde program oluşturuldu. Kalay metali ve Sn katkılı indiyum oksit bileşiği için farklı sıcaklıklarda özdirenç değerleri hesaplandı. Kullanılan metodun geçerliliği, bu katılara uygulamalarıyla birlikte test edildi.
Density Functional Theory Study on Conformers of Benzoylcholine Chloride
(Journal of Spectroscopy, 2013) Karakaya, Mustafa; Ucun, Fatih; Tokatlı, Ahmet
The optimized molecular structures and vibrational frequencies and also gauge including atomic orbital (GIAO) 1H and 13C NMR shift values of benzoylcholine chloride [(2-benzoyloxyethyl) trimethyl ammonium chloride] have been calculated using density functional theory (B3LYP) method with 6-31++G(d) basis set. The comparison of the experimental and calculated infrared (IR), Raman, and nuclear magnetic resonance (NMR) spectra has indicated that the experimental spectra are formed from the superposition of the spectra of two lowest energy conformers of the compound. So, it was concluded that the compound simultaneously exists in two optimized conformers in the ground state. Also the natural bond orbital (NBO) analysis has supported the simultaneous exiting of two conformers in the ground state. The calculated optimized geometric parameters (bond lengths and bond angles) and vibrational frequencies for both the lowest energy conformers were seen to be in a well agreement with the corresponding experimental data.
(E)-2-[4-(Dimethylamino)phenyliminomethyl]- 6-methylphenol
(Acta Crystallographica Section E Structure Reports Online, 2007) Gül, Zarife Sibel; Erşahin, Ferda; Ağar, Erbil; Işık, Şamil
[Abstract Not Available]
(E)-4-Methyl-2-[3-(trifluoromethyl)- phenyliminomethyl]phenol
(Acta Crystallographica Section E Structure Reports Online, 2007) Gül, Zarife Sibel; Erşahin, Ferda; Ağar, Erbil; Işık, Şamil
The molecule of the title compound, C15H12F3NO, is not planar and the dihedral angle between the planes of the two aromatic rings is 33.82 (11) . The molecule exists in the phenol–imine tautomeric form, with a strong intramolecular O—H N hydrogen bond [N O = 2.609 (3) A ° ]
(E)-2-[2-(Hydroxymethyl)phenyliminomethyl]- 6-methylphenol
(Acta Crystallographica Section E, 2007) Gül, Zarife Sibel; Erşahin, Ferda; Ağar, Erbil; Işık, Şamil
The molecule of the title compound, C15H15NO2, is not planar, displaying a dihedral angle of 21.21 (18) between the two aromatic rings. The central N C bond distance of 1.279 (4) A ° is typical for an imine double bond. There are intramolecular O—H N and intermolecular O—H O hydrogen bonds.
(E)-4-Bromo-2-(2-methoxyphenyliminomethyl) phenol
(Acta Crystallographica Section E Structure Reports Online, 2007) Gül, Zarife Sibel; Erşahin, Ferda; Ağar, Erbil; Işık, Şamil
The molecule of the title compound, C14H12BrNO2, is almost planar and the dihedral angle between the planes of the two aromatic rings is 3.8 (2) . The molecule exists in the crystal structure in the phenol–imine tautomeric form, with the H atom located on O rather than on N. This H atom is involved in a strong intramolecular hydrogen bond.
2-Chloro-4-{(E)-[(4-chlorophenyl)imino]- methyl}phenol
(Acta Crystallographica Section E Structure Reports Online, 2012) Şahin, Zarife Sibel; Işık, Şamil
In the title Schiff base compound, C13H9Cl2NO, the dihedral angle between the mean planes of the benzene rings is 10.20 (10) . The crystal structure is stabilized by O—H N hydrogen bonds and weak – stacking interactions [centroid–centroid distance = 3.757 (1) A ° ].
2-[(E)-(Naphthalen-2-ylimino)methyl]- 4-(trifluoromethoxy)phenol.
(Acta Crystallographica Section E Structure Reports Online, 2012) Pekdemir, Merve; Şahin, Zarife Sibel; Işık, Şamil; Ağar, Ayşe Alaman; Yıldırım, Sema Öztürk; Butcher, Ray J.
In the title compound, C18H12F3NO2, the planes of the benzene ring and the naphthalene system form a dihedral angle of 47.21 (3) . The hydroxy group is involved in an intramolecular O—H N hydrogen bond. In the crystal, weak C—H O and C—H F interactions link the molecules related by translations along the c and a axes, respectively, into sheets.
Improvement of superconducting properties of MgB2 by changing the argon ambient pressure and sintering conditions
(Journal of Physics: Conference Series, 2009) Savaşkan, Burcu; Öztürk, Kemal; Çelik, Şükrü; Yanmaz, Ekrem
We have investigated various characteristic properties depending on sintering conditions of MgB2 samples prepared by the standard solid state reaction method. It is inferred from experimental results that the crystallinity of samples were improved when the pressure of the Ar ambient increased. Also, it was found that the sintering temperature above 850 ºC caused extremely high amount of decomposition of the superconductor phase. Finally, it was considered that the sintering process of MgB2 must be carried out under the pressure of Ar ambient higher than 8 bar to impede the volatility of Mg in the structure of MgB2. The Jc values of samples systematically enhanced with the increase of sintering time and in particular, the sample sintered for 180 min. exhibited the highest Jc (0) of 4.9 × 103 A cm?2 at 30 K. The obtained results demonstrate that the sintering conditions of MgB2 have a significant influence on Tc (onset) and Jc, which are directly related to practical applications of MgB2 based superconductor components.
Investigation of effect of x in Yb1-xGdxBa2Cu3O7-y superconducting structures on upper critical magnetic field and coherence length.
(Journal of Physics: Conference Series, 2009) Çelik, Şükrü; Öztürk, Kemal; Yanmaz, Ekrem; info:eu-repo/semantics/openAccess
The resistivity measurements of the Yb1-xGdxBa2Cu3O7-y superconducting samples prepared by using the solid-state reaction technique for x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were performed in QD-PPMS system under different magnetic fields up to 5T in zero field cooling regime. The upper magnetic field Hc2(T=0) for each sample was calculated from 50% of the normalized resistivity (Rn) by the extrapolation Hc2(T) to T=0K and the coherence lengths x(T=0) of the samples were calculated from the Hc2(0) values. The examination of the effects of x in the composition on Hc2(0) showed us that the upper critical magnetic field decreased from 186.31T for x=0.0 to 37.99T for x=1.0 with the increasing of content x from x=0.0 to 1.0. Using the content x in the composition, the upper critical magnetic field can be controlled and this can be used in superconducting application especially as a superconducting relays.

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