https://hdl.handle.net/20.500.11857/1464 Scopus Indexed Publications Collection 2026-06-02T18:53:08Z https://hdl.handle.net/20.500.11857/3706 Biconical reflectance, micro-Raman, and nano-FTIR spectroscopy of the Didim (H3-5) meteorite: Chemical content and molecular variations Yeşiltaş, Mehmet; Kaya, M.; Glotch, T. D.; Brunetto, R.; Maturilli, A.; Helbert, J.; Ozel, M. E. The Didim meteorite contains multiple lithologies and clasts of different petrologic types in a single stone. A mixture of H5 clasts in an unequilibrated H3 host was previously observed in Didim, according to the initial characterization reported in the Meteoritical Bulletin Database, providing an opportunity to investigate molecular composition that contains varying degree of equilibrium with varying mineralogy. We have taken a from large scale to small scale approach to spectroscopically investigate the chemical content of Didim. Centimeter-scale biconical reflectance spectra show that Didim contains abundant olivine, pyroxene, and other optically active minerals, evident from a strong Band I near 0.93 mu m and a weak Band II near 1.75 mu m. Micrometer-scale Raman spectroscopic investigations reveal the presence of carbonaceous material in addition to forsteritic olivine, pyroxene (augite and enstatite), feldspars, and opaque phases such as chromite and hematite. 3-D Raman tomographic imaging shows that the carbonaceous material near chondrules extends underneath a large olivine grain, going further down toward the interior, indicating that the observed carbonaceous matter is likely indigenous. Nano-scale infrared measurements reveal that the observed chemical materials in Didim contain spectral, and therefore, molecular, variations at the similar to 20 nm spatial scale. These chemical variations are normally not accessible via conventional infrared techniques, and indicate the presence of different cations in the molecular composition of observed minerals. By taking the large scale to small scale approach, we show that these compositional variations can be captured and investigated nondestructively in meteorites to understand formation/evolution of chemical components in the parent body. 2020-01-01T00:00:00Z https://hdl.handle.net/20.500.11857/3705 Usefulness of novel Martin/Hopkins and Sampson equations over Friedewald equation in cardiology outpatients: A CVSCORE-TR substudy Dinç Asarcıklı, Lale; Kış, Mehmet; Güvenç, Tolga Sinan; Tosun, Veysel; Acar, Burak; Avcı Demir, Fulya; Zoghi, Mehdi Background and aims The Friedewald equation (LDL-Cf) is known to produce inaccurate estimations of low-density lipoprotein cholesterol (LDL-C) when triglycerides are high (>400 mg/dL) or LDL-C is low (<70 mg/dL). The Martin/Hopkins (LDL-Cmh) and Sampson (LDL-Cs) equations were developed to overcome these limitations, but few data are available to assess whether these equations offer incremental usefulness over LDL-Cf. Our aim was to understand whether there was any incremental usefulness of novel equations on decisions regarding patient management. Methods Four thousand one hundred and ninety-six cardiology patients who were included in a multicentre registry database were analysed. Each patient was assigned to a cardiovascular risk class using the SCORE (Systematic COronary Risk Evaluation) algorithm, and relevant European guidelines were used to assess LDL-C targets. Results Compared with LDL-Cmh and LDL-Cs, LDL-Cf was able to correctly identify 96.9%-98.08% of patients as within or outside the LDL-C target, respectively, and 1.95%-2.8% of patients were falsely identified as being within the LDL-C target. Kappa coefficients for agreement between LDL-Cf vs LDL-Cmh and LDL-Cf vs LDL-Cs were 0.868 and 0.918 (P < .001). For patients not on cholesterol-lowering drugs, the decision to initiate treatment would be different in 1.2%-1.8% of cases if LDL-Cs or LDL-Cmh were used, respectively. For those already on cholesterol-lowering drugs, decisions regarding treatment intensification would be different in 1.5%-2.4% of cases if LDL-Cs or LDL-Cmh were used. Conclusions In most cardiology outpatients, the Friedewald equation has excellent agreement with the novel Martin/Hopkins and Sampson equations, and treatment decisions should not change in most patients. 2021-01-01T00:00:00Z https://hdl.handle.net/20.500.11857/3707 The Saricicek howardite fall in Turkey: Source crater of HED meteorites on Vesta and impact risk of Vestoids Ünsalan, Ozan; Jenniskens, Peter; Yin, Qingzhu; Kaygısız, Ersin; Albers, Jim; Clark, David L.; Schmedemann, Nico The Saricicek howardite meteorite shower consisting of 343 documented stones occurred on September 2, 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Saricicek experienced a complex cosmic-ray exposure history, exposed during 12-14Ma in a regolith near the surface of a parent asteroid, and that an 1m sized meteoroid was launched by an impact 22 +/- 2Ma ago to Earth (as did one-third of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4 +/- 2.5Ma and 4553 +/- 8.8Ma crystallization ages for the basaltic magma clasts. The apatite U-Pb age of 4525 +/- 17Ma, K-Ar age of 3.9Ga, and the U,Th-He ages of 1.8 +/- 0.7 and 2.6 +/- 0.3Ga are interpreted to represent thermal metamorphic and impact-related resetting ages, respectively. Petrographic; geochemical; and O-, Cr-, and Ti-isotopic studies confirm that Saricicek belongs to the normal clan of HED meteorites. Petrographic observations and analysis of organic material indicate a small portion of carbonaceous chondrite material in the Saricicek regolith and organic contamination of the meteorite after a few days on soil. Video observations of the fall show an atmospheric entry at 17.3 +/- 0.8kms(-1) from NW; fragmentations at 37, 33, 31, and 27km altitude; and provide a pre-atmospheric orbit that is the first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data indicate the similarity of Saricicek with the Vesta asteroid family (V-class) spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of meteoroid delivery to Earth shows that the complete disruption of a 1km sized Vesta family asteroid or a 10km sized impact crater on Vesta is required to provide sufficient meteoroids 4m in size to account for the influx of meteorites from this HED clan. The 16.7km diameter Antionia impact crater on Vesta was formed on terrain of the same age as given by the He-4 retention age of Saricicek. Lunar scaling for crater production to crater counts of its ejecta blanket show it was formed 22Ma ago. 2019-01-01T00:00:00Z https://hdl.handle.net/20.500.11857/3704 Embedding of atoms into the nanopore sites of the C6N6 and C6N8 porous carbon nitride monolayers with tunable electronic properties Bafekry, Asadollah; Stampfl, Catherine; Akgenç, Berna; Mortazavi, Bohayra; Ghergherehchi, Mitra; Ch V Nguyen Using first-principles calculations, we study the effect of embedding various atoms into the nanopore sites of both C6N6 and C6N8 monolayers. Our results indicate that the embedded atoms significantly affect the electronic and magnetic properties of C6N6 and C6N8 monolayers and lead to extraordinary and multifarious electronic properties, such as metallic, half-metallic, spin-glass semiconductor and dilute-magnetic semiconductor behaviour. Our results reveal that the H atom concentration dramatically affects the C6N6 monolayer. On increasing the H coverage, the impurity states also increase due to H atoms around the Fermi-level. C6N6 shows metallic character when the H atom concentration reaches 6.25%. Moreover, the effect of charge on the electronic properties of both Cr@C6N6 and C@C6N8 is also studied. Cr@C6N6 is a ferromagnetic metal with a magnetic moment of 2.40 mu(B), and when 0.2 electrons are added and removed, it remains a ferromagnetic metal with a magnetic moment of 2.57 and 2.77 mu(B), respectively. Interestingly, one can observe a semi-metal, in which the VBM and CBM in both spin channels touch each other near the Fermi-level. C@C6N8 is a semiconductor with a nontrivial band gap. When 0.2 electrons are removed, it remains metallic, and under excess electronic charge, it exhibits half-metallic behaviour. 2020-01-01T00:00:00Z