On Approximation Properties of Generalized q-Bernstein Operators

In this study, we identify a generalization of q-Bernstein type operators and investigate approximation properties of a sequence of these operators . We estimate rate of approximation by modulus of continuity. We prove Voronovskaya type theorem for these operators.     

The effect of PVA (Bi2O3-doped) interfacial layer and series resistance on electrical characteristics of Au/n-Si (110) Schottky barrier diodes (SBDs)

Two types of Schottky Barrier Diodes (SBDs) with and without PVA (Bi₂O₃-doped) polymeric interfacial layer, were fabricated and measured at room temperature in order to investigate the effects of the PVA (Bi₂O₃-doped) interfacial layer on the main electrical parameters such as the ideality factor (n), zero-bias barrier height (Φ_B0), series resistance (R_s) and interface-state density (N_ss). Electrical parameters of these two diodes were calculated from the current-voltage (I-V) characteristics and compared with each other. The values of Φ_B0, n and R_s for SBDs without polymeric interfacial layer are 0.71 eV, 1.44 and 4775 Ω, respectively. The values of Φ_B0, n and R_s for SBDs with PVA (Bi₂O₃-doped) polymeric interfacial layer are 0.74 eV, 3.49 and 10,030 Ω, respectively. For two SBDs, the energy density distribution profiles of interface states (N_ss) were obtained from forward-bias I-V measurements by taking the bias dependence of R_s of these devices into account. The values of N_ss obtained for the SBD with PVA (Bi₂O₃-doped) polymeric interfacial layer are smaller than those of the SBD without polymeric interfacial layer.     

Determination of the ground- and excited-state dipole moments of 4’-(hexyloxy)-4-biphenylcarbonitrile and 4-isothiocyanatophenyl 4-pentylbicyclo [2,2,2] octane-1-carboxylate nematic liquid crystals and their mixtures

The dipole moments of the ground and excited states of 4′-(hexyloxy)-4-biphenylcarbonitrile and 4-isothiocyanatophenyl 4-pentylbicyclo [2.2.2] octane-1-carboxylate nematic liquid crystals and their mixtures prepared in chloroform and dichloromethane were studied at room temperature. The dipole moments of the ground states of the all samples were calculated according to the Guggenheim–Smith method. The dipole moments of their excited states were determined with the help of the Lippert equation by measuring the absorption and fluorescence spectra, solvent polarity and refractive index values. It was determined that dipole moments of the excited states were higher than those of the ground states. Moreover, the dipole moments of the ground and excited states of two nematic liquid crystals were also estimated by using molecular mechanic method (Gaussian09 program (DFT/B3LYP 6-31G(dp)). The results obtained are interpreted in detail.     

Syntheses, characterization, antimicrobial and genotoxic activities of new Schiff bases and their complexes

Two new Schiff base ligands (L¹, L²) have been prepared from the reaction of 2,6-diacetylpyridine and 2-pyridinecarboxyaldehyde with 4-amino-2,3-dimethyl-1-phenyl-3-pyrozolin-5-on, and their Co(II), Cu(II), Ni(II), Mn(II), and Cr(III) metal complexes have also been prepared. The complexes are formed by coordination of N and O atoms of the ligands. Their structures were characterized by physico-chemical and spectroscopic methods. The analytical data shows that the metal to ligand ratio in the Schiff base complexes is 1:2. The Schiff base ligands and all complexes were evaluated for their in vitro antibacterial and antifungal activities by the disc diffusion method. In addition, the genotoxic properties of the ligands were studied.     

Poly(vinylferrocenium) coated disposable pencil graphite electrode for DNA hybridization

Poly(vinylferrocenium) (PVF⁺) modified electrode was developed in this study for the electrochemical sensing of DNA based on the oxidation signals of polymer, adenine and guanine. Experimental parameters, such as; polymeric film thickness, DNA immobilization time and DNA concentration were examined in order to obtain more sensitive and selective electrochemical signals. After optimization studies, DNA hybridization was investigated.     

In vivo biodistribution of <Superscript>131</Superscript>I labeled bleomycin (BLM) and isomers (A2 and B2) on experimental animal models

Bleomycins (BLMs; BLM, A2, and B2) were labeled with ¹³¹I and radiopharmaceutical potentials were investigated using animal models in this study. Quality control procedures were carried out using thin layer radiochromatography (TLRC), high performance liquid chromatography (HPLC), and liquid chromatography (LC/MS/MS). Labeling yields of radiolabeled BLMs were found to be 90, 68, and 71%, respectively. HPLC chromatograms were taken for BLM and cold iodinated BLM (¹²⁷I-BLM). Five peaks were detected for BLM and three peaks for ¹²⁷I-BLM in the HPLC studies. Two peaks belong to isomers of BLM. The isomers of BLM were purified with using HPLC. Biological activity of BLM was determined on male Albino Wistar rats by biodistribution and scintigraphic studies were performed for BLMs by using New Zelland rabbits. The biodistribution results of ¹³¹I-BLM showed high uptake in the stomach, the bladder, the prostate, the testicle, and the spinal cord in rats. Scintigraphic results on rabbits agrees with that of biodistributional studies on rats. The scintigraphy of radiolabeled isomers (¹³¹I-A2 and ¹³¹I-B2) are similiarly found with that of ¹³¹I-BLM.     

Synthesis, characterization and aggregation behaviour of novel peripherally tetra-substituted octacationic water soluble metal-free and metallophthalocyanines

In this study, a new phthalonitrile derivative 3 bearing 1,3-bis[3(dimethylamino)phenoxy]propan-2-ol 1, metal-free phthalocyanine (Pc) 4, metallophthalocyanines (MPcs) 5–7 and their quaternized derivatives 4a–7a were synthesized. Metal-free Pc 4 was prepared by cyclotetramerization of phthalonitrile derivate 3 and MPcs 5–7 were synthesized by heating 3 with NiCl₂, CoCl₂ and CuCl₂ in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively. Quaternization of the dimethylamino functionality produced quaternized octacationic water soluble metal-free, Ni, Co and Cu Pcs which were soluble in water, DMF, DMSO. The aggregation behaviour of these compounds were investigated in different concentrations of chloroform for metal-free, Ni, Co and Cu Pcs. The effect of solvents on absorption spectra were studied in various organic solvents. The novel compounds were characterized using IR, ¹H-, ¹³C NMR, UV–vis and MS spectral data.