Yazar "Yildiz, Mustafa" seçeneğine göre listele

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    Electrical performance of a nanocomposite diode based on palladium nanoparticles- and polyethyleneimine functionalized nitrogen-doped graphene quantum dots
    (Nature Portfolio, 2025) Dikicioglu, Elanur; Efkere, Halil Ibrahim; Yildiz, Mustafa; Orhan, Elif
    A nanocomposite material comprising palladium nanoparticles (PdNPs) doped with polyethyleneimine (PEI)-functionalized nitrogen-doped graphene quantum dots (PEI N-GQDs) was synthesized and employed as an interlayer in an Ag/PdNPs/PEI N-GQDs/p-Si heterojunction configuration. The PdNPs/PEI N-GQDs nanocomposite was prepared through an aqueous reaction between PEI-functionalized N-GQDs and Pd(NO2)2H2O and characterized using FTIR, UV-Vis, TEM, XPS, and PL spectroscopy. The PL spectrum exhibited a broad emission centered at 580 nm (2.14 eV) with a near-infrared tail, indicating defect-assisted recombination and confirming the semiconducting nature of the nanocomposite. The Ag/PdNPs/PEI N-GQDs/p-Si diode displayed a rectification ratio of approximately 1.64 x 102 at +/- 4 V, with barrier heights of 0.87, 0.76, and 0.68 eV obtained from thermionic-emission (TE), Cheung, and Norde methods, respectively. Energy band alignment analysis revealed that the rectifying behavior originates from the Ag/nanocomposite interface, forming a Schottky-type barrier, while a type-II staggered junction is established at the nanocomposite/p-Si interface, facilitating hole transport. These findings demonstrate the potential of PdNPs/PEI N-GQDs as an effective interlayer material for carbon-based nanoelectronic and optoelectronic devices.
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    Enhanced Rectification of Lanthanum Hydroxide-Doped Graphene Quantum Dots/Silicon Heterostructures at Cryogenic Temperatures
    (Wiley, 2025) Altan, Aslihan Anter; Berktas, Zeynep; Kaymak, Nuriye; Yildiz, Mustafa; Di Bartolomeo, Antonio; Orhan, Elif
    This study reports the fabrication and temperature-dependent electrical characterization of a heterojunction formed by lanthanum(III) hydroxide nanoparticles doped with polyethyleneimine-functionalised nitrogen-doped graphene quantum dots (La(OH)3NPs/PEI N-GQDs) on n-type silicon (n-type Si). The heterostructure exhibits diode-like behaviour in the 77-400 K temperature range, with rectification exceeding two orders of magnitude and increasing as the temperature decreases, reaching an exceptionally high value above 10(5) at 77 K. Temperature-dependent diode parameters, including barrier height, series resistance, and ideality factor, are extracted using the thermionic emission model, revealing that barrier height increases and ideality factor decreases with rising temperature. These trends, along with significant deviations from the ideal Richardson behaviour of Schottky diodes, are effectively explained by the Werner-G & uuml;ttler model, which attributes them to Gaussian spatial inhomogeneities of the barrier arising from interface states and nanocomposite-induced fluctuations. This study highlights the robust rectifying behaviour, excellent cryogenic performance, and wide-temperature applicability of the La(OH)3NPs/PEI N-GQDs on the Si heterostructure, establishing it as a promising platform for low-power diode applications under extreme thermal conditions.
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    Panax ginseng protects against copper sulfate-induced kidney toxicity in rats
    (Wolters Kluwer Medknow Publications, 2025) Gules, Ozay; Yildiz, Mustafa; Boyacioglu, Murat; Sevimli, Alper; Dayi, Belma
    Objective:To assess the protective effects of Panax ginseng (PG) against copper sulfate (CuSO4)-induced kidney toxicity in rats.Methods:The rats were randomly allocated into four groups: control, CuSO4, PG, and PG+CuSO4. The experiment continued for 14 days, during which CuSO4 was provided at a dosage of 100 mg/kg body weight per day and PG at 300 mg/kg body weight by oral gavage per day. Upon completion of the experiment, kidney sections were used for histological and histomorphometric analyses. The histochemical method was applied to ascertain the density of the glomerular mesangial matrix. The expressions of vascular endothelial growth factor (VEGF) and caspase-3 were examined using immunohistochemistry. The levels of malondialdehyde and glutathione, along with the activity of superoxide dismutase and catalase in the kidney, were measured.Results:PG treatment exhibited a marked protective effect against CuSO4-induced renal damage, as evidenced by improved histopathological lesions, significantly reduced glomerular mesangial matrix density, VEGF in distal tubules, caspase-3 expression, and malondialdehyde levels in renal tissue, as well as enhanced superoxide dismutase and catalase activities.Conclusions:PG treatment ameliorates CuSO4-induced kidney injury in rats. Further studies are warranted to verify its efficacy and elucidate the underlying mechanism of its nephroprotective action.