Scopus İndeksli Yayınlar Koleksiyonu

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  • Article
    Depositional Model, Cyclicity, and Hydrocarbon Potential of the Eocene Sakesar Carbonate Ramp, Salt Range, Pakistan
    (Springer, 2026-02-02) Shah, Syed Bilawal Ali; Shah, Syed Haider Ali
    The Sakesar Formation in the Salt Range, Pakistan, represents a well-developed Eocene carbonate ramp deposited along the southern Tethyan margin. This study integrates petrographic analysis, palynofacies evaluation, organic geochemical measurements and sequence stratigraphic interpretation to characterise the depositional environments, diagenetic evolution, and petroleum system potential of the formation. Six microfacies (MF1-MF6) were identified through thin-section petrography ranging from high-energy shoal grainstones to low-energy lagoonal marls. Quantitative palynofacies analysis shows energy dependent trends in organic matter composition, with shoal facies dominated by opaque phytoclasts and lagoonal facies enriched in amorphous organic matter (AOM). Organic geochemical measurements including Total Organic Carbon (TOC), Hydrogen Index (HI), Oxygen Index (OI), and Rock-Eval pyrolysis parameters, combined with vitrinite reflectance (Ro) data, indicate that lagoonal marl-micrite facies (MF6) contain Type II kerogen with the highest TOC values (2.80%), elevated HI (293 mg hydrocarbons per gram TOC), and peak oil-window maturity (0.72% Ro). These attributes identify MF6 as the primary oil-prone source rock. Mid-ramp wackestones and packstones (MF3-MF4) possess moderate generative potential and serve as internal seals or baffles, whereas high-energy shoal facies (MF1-MF2) show favourable reservoir characteristics but limited source potential. Sequence-stratigraphic analysis demonstrates that maximum flooding surfaces (MFS) frequently coincide with organic-rich MF6 intervals, producing predictable vertical stacking of source, seal, and reservoir units at parasequence scale. The integrated petrographic, palynofacies, and geochemical framework confirms the dual role of the Sakesar Formation as both a reservoir and a source-seal interval, with metre-scale cyclicity enhancing hydrocarbon charge and trapping efficiency. These findings refine the depositional and petroleum system model of the Sakesar carbonate ramp and provide valuable predictive analogues for Eocene carbonate exploration within the Himalayan foreland basin and related Tethyan settings.
  • Article
    Citation - WoS: 17
    Citation - Scopus: 23
    Women's Tertiary Education Masks the Gender Wage Gap in Turkey
    (Springer, 2017-03-10) Tekguc, Hasan; Eryar, Deger; Cindoglu, Dilek
    This paper investigates the gender wage gap for full-time formal sector employees, disaggregated by education level. The gap between the labor force participation rate of women with tertiary education and those with lower levels of education is substantial. There is no such gap for men. Hence, existing gender wage gap studies for Turkey, where we observe lopsided labor force participation rates by education levels, compare two very different populations. We disaggregate the whole sample by education level to create more homogenous sub-groups. For Turkey, without disaggregation, the gender wage gap was 13% in 2011, and women are significantly over-qualified relative to men on observed characteristics. Once we disaggregate the sample by education level, we show that the gender wage gap is 24% for less educated women and 9% for women with tertiary education in full-time formal employment. Observed characteristics only explain 1 % of this gap in absolute terms. We further disaggregate the data by public and private employment. The gender gap is higher in the private sector. However, women with tertiary education in the public sector are significantly better qualified compared to men, and consequently the adjusted gender wage gap is higher for women with tertiary education in the public sector. Our estimates also indicate a rise in the gender wage gap between 2004 and 2011.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Theoretical Investigation of Substituent Effects on the Relative Stabilities and Electronic Structure of [BnXn]2- Clusters
    (Springer, 2021-11-29) Tahaoglu, Duygu; Alkan, Fahri; Durandurdu, Murat
    In this study, we provide a theoretical evaluation of relative stabilities and electronic structure for [BnXn](2-) clusters (n = 10, 12, 13, 14, 15, 16). Structural and electronic characteristics of [BnXn](2-) clusters are examined by comparison with the [B12X12](2-) counterparts with a focus on the substituent effects (X = H, F, Cl, Br, CN, BO, OH, NH2) on the electronic structure, electron detachment energies, formation enthalpies, and charge distributions. For the electronic structure and electron detachment energies, substituent effects on boron clusters are shown to follow a very similar trend to the mesomeric and inductive effects (+/- M and +/- I) of pi-conjugated systems, and the most stable derivatives in terms of HOMO/LUMO and electron detachment energies are calculated for CN and BO substituents due to strong -M effects. In the case of formation enthalpies for larger boron clusters (n >= 13), the icosahedral barrier is shown to increase with the halogen and CN substitution, whereas it is possible to reduce the icosahedral barrier for the cases of X = OH and NH2. It is shown that this reduction results from destabilizing the [B12X12](2-) cluster with electronic (+ M) and symmetry effects induced by OH and NH2 ligands.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 12
    The Effect of Dilute Nitrogen on Nonlinear Optical Properties of the IngaAsN/GaAs Single Quantum Wells
    (Springer, 2012-09-26) Koksal, K.; Sahin, M.
    In this study, we investigate the linear and third order nonlinear optical properties of InGaAsN/GaAs depending on nitrogen content and laser dressing parameter. As theoretical models, band anticrossing and model solid theory are used. In order to obtain the electronic properties of the quantum well, the finite difference method is used. The laser beam affects the electronic properties of the quantum well by changing the shape of the confinement potential. This modification of the potential is determined by laser dressing parameter. By using dilute amount of nitrogen, conduction band and the depth of quantum well can be controlled. The strain which is introduced due to the presence of nitrogen can be compensated by using indium atoms. The electronic and the linear and third order nonlinear optical properties of InGaAsN/GaAs quantum well structure are obtained.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 11
    T Cells in Tumor Microenvironment
    (Springer, 2015-10-18) Kiraz, Yagmur; Baran, Yusuf; Nalbant, Ayten
    Tumors progress in a specific area, which supports its development, spreading or shrinking in time with the presence of different factors that effect the fate of the cancer cells. This specialized site is called "tumor microenvironment" and has a composition of heterogenous materials. The immune cells are also residents of this stromal, cancerous, and inflammatory environment, and their types, densities, or functional differences are one of the key factors that mediate the fate of a tumor. T cells as a vital part of the immune system also are a component of tumor microenvironment, and their roles have been elucidated in many studies. In this review, we focused on the immune system components by focusing on T cells and detailed T helper cell subsets in tumor microenvironment and how their behaviors affect either the tumor or the patient's outcome.
  • Article
    Citation - WoS: 31
    Citation - Scopus: 32
    Synthesis and Characterization of Chitosan-Vermiculite Composite Beads for Removal of Uranyl Ions: Isotherm, Kinetics and Thermodynamics Studies
    (Springer, 2020-11-19) Senol, Zeynep Mine; Simsek, Selcuk; Ozer, Ali; Senol Arslan, Dilek
    In this study, a new material containing Chitosan (Ch)-Vermiculite (V) composite beads was synthesized with epichlorohydrin cross-linking agent and used to remove uranyl ions from the aqueous solution. The prepared new material was characterized by SEM, XRD, FTIR analyses and PZC measurement. The effects of significant parameters on adsorption including temperature, pH, concentration and time were investigated. The obtained results indicated that the new composites of Ch-V was revealed in different structure. The zeta potential analyses showed that electrostatic attraction existed during the adsorption process between the uranyl ions and Ch-V. The maximum adsorption capacity of material was calculated as 0.665 mol kg(-1) by considering Langmuir equation. Adsorption kinetic was also explained with pseudo second order and intra particular diffusion models. Experimental studies clearly showed that the adsorption was endothermic and occurred spontaneously. The newly developed smart material has many advantages such as reusability, high adsorption capacity, selectivity and economics.
  • Article
    Square Root Computation in Finite Fields
    (Springer, 2024-03-12) Adiguzel-Goktas, Ebru; Ozdemir, Enver
    In this paper, we present a review of three widely-used practical square root algorithms. We then describe a unifying framework where each of these well-known algorithms can be seen as a special case of it. The framework with singular curves offers a broad perspective to compare and further improve the existing methods in addition to offering a new avenue for square root computation algorithms in finite fields.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Separation of Mn and Fe From a Manganiferous Iron Ore Using Horse Dung as Reductant: A Zero Waste Approach
    (Springer, 2022-01-13) Top, Soner; Altiner, Mahmut; Kursunoglu, Sait
    The separation of manganese and iron from a manganiferous iron ore using horse dung (biomass) as reductant was investigated in a sulfuric acid solution, and 99.80% Mn and 17.76% Fe were extracted into the solution under these leaching conditions: 1 M sulphuric acid concentration, 120 g/L biomass, 1/10 solid to liquid ratio, 300 rev/min stirring speed, 90 degrees C leaching temperature, and 3 h leaching time. In the first precipitation step, the iron and aluminum were first rejected from the solution at pH 5.04. Thereafter, 98.58% Mn was precipitated at pH 10 in the second step. The precipitate was identified as a pyrochroite mineral. After the leaching, the residue was subjected to a carbothermal reduction process conducted at 700 degrees C for 10 min in the presence of no extra reductant. The residue was converted to magnetite mineral, which can be easily recovered by magnetic separation. Based on the experimental results, a flowsheet has been proposed.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 4
    Separation of Fe and Mn From Manganiferous Iron Ores via Reductive Acid Leaching Followed by Magnetic Separation
    (Springer, 2019-08-01) Top, S.
    In this study, a process to separate manganese and iron from manganiferous iron ores by reductive acid leaching followed by magnetic separation was conceived and experimentally tested. In the leaching process, sulfuric acid was used as lixiviant and oxalic acid was used as reductant. The experimental results showed that the manganese and iron separation was optimum when the concentration of the sulfuric acid and oxalic acid were 0.75 M and 30 g/L, respectively, at a temperature of 80 °C, a solid/liquid ratio of 67 g/L, stirring speed of 400 rpm, and leaching duration of 60 min. Under this condition, 90.49% and 6.78% of Mn and Fe were dissolved, respectively, from the ore sample with a size fraction of − 106 μm. It was determined that the leaching of manganese from the ores was a second-order reaction with an activation energy (E<inf>a</inf>) of 53.38 kJ/mol. The leaching residues obtained under the optimum condition were subjected to high-intensity wet magnetic separation tests to recover the remaining iron content. This separation process produced a concentrate containing 56.20% Fe and 1.79% Mn with iron and manganese recoveries of 56.83% and 66.73%, respectively. A magnetic separation test from an unleached ore sample was also carried out as a benchmark. To the best of our knowledge, this is the first time that a magnetic separation process was used to a residue obtained from reductive acid leaching of manganiferous iron ores to recover iron. © 2019, Society for Mining, Metallurgy & Exploration Inc.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Recovery of Lithium From Spent Coin-Type Lithium Manganese Dioxide Cr Cells by Acidic Leaching in the Presence of Potassium Permanganate as Oxidant
    (Springer, 2022-09-20) Kursunoglu, Sait; Top, Soner; Altiner, Mahmut; Ozsarac, Safak; Kaya, Muammer
    The selective leaching of lithium from spent coin-type lithium manganese dioxide CR cells by oxidative leaching and precipitation of Li2CO3 from Li-bearing leach solution has been experimentally and theoretically investigated. The oxidative leaching experiments were carried out using sulfuric acid in the presence of potassium permanganate (KMnO4). The dissolutions of lithium, manganese, nickel, and cobalt were found to be 84.8%, 0.9%, 46.6%, and 9.7%, respectively. The results demonstrated that a considerable amount of manganese and cobalt remained in the leach residue. The Li-bearing leach solution was fed to an impurity removal stage. It was observed that a substantial amount of lithium loss, along with manganese, nickel, and cobalt, was determined at pH 10. At standard temperature and pressure, the species of lithium as a function of pH, lithium concentration, and carbonate concentration was evaluated for the generation of Li2CO3 from the oxidative leach solution. The results revealed that the precipitation of lithium as lithium carbonate is thermodynamically feasible from the solution at high pHs.