Araştırma Çıktıları | TR - Dizin

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Browsing by Subject "Atomik ve Moleküler Kimya"

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    Spectroscopic and luminescence properties of an isonicotinic acid
    (2005) FEHMI BARDAK; Nurdoğan CAN; Sözerli Şebnem Esen CAN; AHMET ATAÇ
    An isonicotinic acid N-oxide Zn(II) compound was characterized on the basis of elemental analysis. FTIR spectra of the compound and free isonicotinic acid N-oxide (INO) were recorded in the range 4000-400 $cm^{-1}$. Cathodoluminescence (CL) spectra from the $Zn(INO)_2$ complex were recorded. The luminescence data were interpreted in terms of the emission band at 470 nm. The green luminescence $(\\sim 470 nm)$ arises from $Zn^{2+}$ transition $^4T_1(^4G)\\rightarrow ^6A_1 (^6S)$. It shows a weak vibronic structure, and short lifetimes less than 150 $\\mu s$. The lifetime and intensity of the signal are temperature dependent, and the parameters are reported for the 470 nm emission line.
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    Investigation of the multipolarity of electromagnetic transitions in $^88,90Kr$ nuclei
    (2006) İhsan ULUER; Sait İNAN; Davut OLGUN; Nurettin TÜRKAN
    We have determined the most appropriate Hamiltonian that is needed for present calculations of nuclei about the A=80 region by the view of Interacting Boson Model-2 (IBM-2). After obtaining the best Hamiltonian parameters, level energies and B(E2) probabilities of some transitions in $^{88,90}Kr$ nuclei were estimated. Results are compared with previous experimental and theoretical data and it is observed that they are in good agreement.
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    Heisenberg, Nedensellik ve Determinizm
    (2007) Haşim Cem ÇELİK
    Bilimsel çalışmalarda çeşitli yönleriyle zaten ele alınmış olan bu konu birçok yönden başka konularla karşılıklı etkileşimleri içinde, bütünsel olarak değerlendirilmelidir. Bu değerlendirme yapılırken dönemin sosyal ve siyasi koşulları da dikkate alınırsa, konuların anlaşılır hale gelebilme şansı artar. Doğa bilimlerindeki devrimsel atılımlar bu sosyal psikolojik koşulları daha ileri bir noktaya taşıyabildiği gibi, geriye doğru bir sıçrama da yaşanabilir. Dönemi itibariyle Newton'un mekanik yasaları, aklın özgürleşmesi ve doğanın anlaşılmasında ileriye doğru itilim sağlayan devrimci bir işlev görmüştür. 1900'lü yılların başında ortaya çıkan, doğanın daha bütünsel bir resmini sunan kuantum mekaniği ise çıkışı itibariyle ciddi bir kafa karışıklığına yol açmış ve o güne kadar elde edilen kavramsal kazanımları da geriye doğru sıçratan bir anlayışın oluşmasına katkıda bulunmuştur. Bu makale bu geri sıçramayı eleştirel bir açıdan sorgulamakta ve aksini iddia ederek yeni gelişmelerle kuantum mekaniksel bulgulamaların, doğayı anlayıp değiştirme ve dönüştürme noktasında çok daha yetkin bir araç haline gelebileceği görüşünü savunmaktadır.
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    Comparison of IBM-2 calculations with X(5) critical point symmetry for low-lying states in $^{144-154} Nd$
    (2008) İLYAS İNCİ; Davut OLGUN; Nurettin TÜRKAN; Sait İNAN
    The X(5) would take place when moving continously from the pure U(5) symmetry to the SU(3) symmetry and it implies a definite relations among the level energies and among the E2 transition strengths. It was recently shown that a signature of phase transition is observed in the chain of Sm, Mo and Nd isotopes, where $^{152}Sm,^{104}Mo$ and $^{150}Nd$ display the predicted features of the X(5) symmetry and mark therefore the critical point. However, more detailed studies and experiments are needed to get ideas about this signature. Without entering into detail we have firstly compared the results obtained in our previous study [15] of $^{144-154}Nd$ with that of the limits in X(5) symmetry and then given a clear descripton about the validity of the Hamiltonian parameters used in the study. At the end, we have concluded that some of Nd isotopes display X(5) symmetry features.
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    Generalized statistical mechanics for nucleus
    (2008) Ramazan ATİCİ; Özhan KAYACAN; HALİL BABACAN
    In this study, we derived the grand partition function and some thermodynamical quantities of the nucleus in the high temperature limit by adopting the ideal Fermi gas partition function of generalized Tsallis thermostatistics. The behaviour of number of neutron and internal energy are depicted as a function of temperature. Sensitivity of q entropy index to the number neutron are also analyzed.
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    The study of dependence of the radial parts of $0^-\\rightarrow 0^+$ first forbidden $\\beta$-decay matrix elements on the parameters in Woods-Saxon potential
    (2008) İsmail KENAR; İsmail MARAŞ; SERDAR ÜNLÜ
    Abstract-In this paper, $0^-\\rightarrow 0^+$ first forbidden $\\beta$-decay matrix elements have been calculated. For $^{206-214}Pb\\rightarrow ^{206-214}Bi$ transitions relativistic $M^{\\pm}(P_A,\\lambda=0)$ and nonrelativistic $M^{\\pm}(j_A,K =1,\\lambda=0)$ matrix elements have been calculated. In this calculations, the eigenfunctions and eigenvalues of Schrodinger equation solved by the more realistic Woods-Saxon potential have been used. The dependence of the radial parts in the matrix elements on the parameters ($r_0$: the radii of nucleus, $\\eta$: isovector parameter, $r_c$: Coulomb radius and $\\chi$ diffusion parameter) of Woods-Saxon potential has been investigated.
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    Annual dose measurement for luminescence dating in Salihli, Turkey
    (2009) TURGAY KARALI; Elçin Ekdal TEKİN; Nurdoğan CAN; Arzu Ege
    Determination of the annual dose level of an area is one of the most important parameters in calculating the geological and archaeological age of the sample using luminescence techniques. Therefore, the concentrations of the natural radionuclides in soils and samples have to be determined since naturally occurring radioactivity provides a major contribution to the annual dose. In this study, the annual dose level of Salihli, Turkey, was determined with 2 different methods: an indirect method that involves the measurement of the concentrations of the naturally occurring radionuclides and a direct method in which thermoluminescence dosimeters (TLDs) are used. The concentrations of the natural radionuclides in soil samples were determined using HPGe γ-ray spectrometry. In the direct method, $Al_2O_3:C$ thermoluminescence dosimeters were used. These dosimeters were chosen because of their high sensitivity and usability in dating studies. The results obtained from both methods were compared and discussed.
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    E(5) behaviour of the Ge isotopes
    (2010) İsmail MARAŞ; Nureddin TURKAN
    The sufficient aspects of model leading to the E(5) symmetry have been proved by presenting E(5) characteristic of the transitional nuclei $^{64-80}Ge.$ The positive parity states of even-mass Ge nuclei within the framework of Interacting Boson Model have been calculated and compared with the Davidson potential predictions along with the experimental data. It can be said that the set of parameters used in an calculations is the best approximation that has been carried out so far. Hence, Interacting Boson Approximation (IBA) is fairly reliable for the calculation of spectra in such set of Ge isotopes.
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    Calculation of generalized level densities for nuclei in mass region 20 < A < 50
    (2010) O. KAYACAN; H. BABACAN
    In this study, a relation between generalized level density and standard level density is derived. Using this relation and Bethe formula of Fermi gas model for standart level density we obtained a generalized nuclear level density formula for nucleus. Generalized level densities were calculated for some nuclei in mass region between 20 and 50 for different q values close to 1 . Our results explain experimental data better than those of Gilbert-Cameron (GC) and Rohr, which are two of the leading compilations in evaluating nuclear level density.
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    The investigation of even-even $^{114-120}Xe$ isotopes by the framework of IBA
    (2010) Ramazan GÜMÜŞ; İsmail MARAŞ; Nurettin TÜRKAN
    In this work, the ground state, quasi beta and quasi gamma band energies $of ^{114,116,118,120}$ Xe isotopes have been investigated by using the both (IBM-1 and IBM-2) versions of interacting boson model (IBM). In calculations, the theoretical energy levels have been obtained by using PHINT and NP-BOS program codes. The presented results are compared with the experimental data in respective tables and figures. At the end, it was seen that the obtained theoretical results are in good agreement with the experimental data.
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    Search on results of IBM for region between $120 \\leq A \\leq 150:^{120-128} Te$ and $^{122-134}Xe$ nuclei
    (2011) İsmail MARAŞ; Nureddin TURKAN
    In this work, the energy levels and transition probabilities B(E2) of some even-even Te (Z=52, N=68-80 and N=84) and even-even Xe nuclei (Z=54, N=68-80 and N=84-88) have been investigated by using the interacting boson model (IBM-1 and IBM-2). The results were compared with some previous experimental and theoretical values. It was seen that an acceptable degree of agreement between the predictions of the model (IBM-1 and IBM-2) and the experiment is achieved.
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    The investigation of $^{130,132}Te$ by IBM-2
    (2012) İsmail MARAŞ; Nureddin TURKAN; Sait İNAN
    In this study, we determined the most appropriate Hamiltonian that is neededfor present calculations of nuclei in the A $/cong$ 130 region by interacting boson model. The second version of interacting boson model (IBM-2) has been widely used for describing the quadrupole collective states of the medium heavy nuclei. The proton and neutron variables are distinguished when this version of the model is applied. Because it is important to describe the proton and neutron variables explicitely. Using the best-fittedvalues of parameters in the Hamiltonian of the IBM-2, we have calculated energy levels and B(E2) values for $^{130,132}Te$. The results were compared with the previous experimental and theoretical data and it is observed that they are in good agreement. Some B(E2) values that are still not known so far are stated and the set of parameters used in these calculations is the best approximation that has been carried out so far. It has turned out that the interacting boson approximation (IBA) is fairly reliable for thecalculation of spectra in the entire set of such Te isotopes.
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    Buji ile Ateşlemeli Bir Motorda Sentetik Mangan Katkısı ile Fuzel Yağı-Benzin Karışımlarının Performans ve Emisyonlara Etkilerinin İncelenmesi
    (2022) Suleyman Ustun; Metin Gürü
    İklim değişikliği, fosil yakıtların azaltılmasını ve yenilenebilir enerji kaynaklarının artırılmasını zorunlu kılmaktadır. Diğer taraftan, COVID-19 süreci dezenfektan ihtiyacını artırmış olup, alkolün yakıt olarak kullanımı yasaklanmıştır. Dezenfektan olarak kullanılamayan fuzel yağı, şeker fabrikalarında pancar melasından etil alkol üretimi sonrası geriye kalan çok kötü kokulu atık alkol karışımıdır. Bu çalışmada benzin içerisine farklı volumetrik oranlarda fuzel yağı ve sentetik mangan katkısı ilave edilerek motor performansı, özgül yakıt tüketimi ve emisyonlar üzerindeki etkileri incelenmiştir. Volumetrik yakıt karışımları olarak %5, %10, %15 ve %20 oranları belirlenmiştir. Karışımların viskozite, donma noktaları, parlama noktaları baz alınarak yapılan testlerde laboratuvar şartlarında benzin içerisine %15 fuzel yağı eklenmesi en uygun ideal karışım (F15B85) olarak belirlenmiştir. F15B85 test yakıtı içerisine sırasıyla 4-8-12 ve 16 ppm organik reçine esaslı mangan katkı maddesi ilave edilerek 4ppmF15B85, 8ppmF15B85, 12ppmF15B85, 16ppmF15B85 deneysel yakıtları oluşturulmuştur. Elde edilen deneysel yakıtlar atmosferik şarjlı benzinli bir motorda ölçüm testleri yapılarak motor performansı ve emisyon değerleri incelenmiştir. Deneysel sonuçlara göre 12ppmF15B85 yakıtı motor performans ve emisyonlar açısından diğer yakıt karışımlarına göre olumlu sonuçlar vermiştir. Motor performanslarında ortalama olarak torkta %4,18, güçte %5,04, BSFC (Fren özgül yakıt tüketimi)’de %3,12 artış, EGT (Egzoz gaz sıcaklığı)’de %2,48 azalma tespit edilmiştir. Egzoz emisyonları açısından bakıldığında CO (Karbonmonoksit) ve HC (Hidrokarbon)’de sırasıyla ortalama olarak %20,69, %10,51 azalma, CO2 (Karbondioksit) ve NOx (Azotoksit) de ise %3,65, %5,10 artış tespit edilmiştir. 
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    Prebiotic Chemistry and Sepiolite: A Density Functional Theory Approach
    (2024) deniz karatas
    Sepiolite, a natural clay mineral, offers a large surface area due to its fibrous structure, allowing it to exhibit adsorption properties. In this study, the molecular interactions of sepiolite, a biocompatible clay mineral known as a biomaterial, and purine and pyrimidine molecules forming the bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) molecules were modeled by Density Functional Theory. In addition to geometry optimization, calculations of interaction energy, bond critical points, and electrostatic potential revealed that essential molecules for our source of life interact with basal surface of the clay. For example, the best interaction energies between bases/sepiolite were found to be -127.47 kJ/mol for guanine and -121.35 kJ/mol for cytosine, respectively. Looking at the modeling results, one of the most important factors affecting the interaction energies is hydrogen bonding. To reveal this, bond critical point analysis was performed, and it was computed that a large amount of intermolecular interaction energies came from hydrogen bonds. For example, it was calculated that approximately 70% of the total energy in the guanine/TOT (two tetrahedra and one octahedron) model comes from hydrogen bonds. Furthermore, this value for the cytosine/TOT model was found to be around 72%. The most effective indices in these two models are 145 and 135, with the H- bond energies recorded as -22.41 and -31.41 kJ/mol, respectively. Considering all analyses, it can be concluded that basal surfaces of sepiolite serve as suitable hosts for nitrogenous bases, which are the basic components of life. The aim of this study is to show that sepiolite offers an important surface feature to protect and stabilize DNA and RNA nucleic acid bases, which are necessary for the existence of living organisms, and to reveal the existence of a robust adsorption interaction between sepiolite and bases, thanks to the surface and chemical properties of sepiolite.