Mehmet Balcan

The determination of the heats of combustion and the resonance energies of some substituted naphthalenes

Abstract In this study, some heats of combustion and resonance energies for 1-substituted naphthalenes have been determined. The heats of combustion of naphthalene, 1-naphthol, 1-naphthylamine, 1-methylnaphthalene, 1-fluoronaphthalene, 1-naphthylacetate and 1-naphthoic acid were determined as 1230.90 ± 1.23, 1183.34 ± 1.18, 1263.35 ± 1.26, 1382.17 ± 1.38, 1217.97 ± 1.22, 1383.92 ± 1.38, and 1221.49 ± 1.22 kcal mol −1 respectively. The resonance energies of naphthalene, 1-naphthol, 1-naphthylamine and 1-methylnaphthalene were calculated to be 74.0 ± 1.2, 73.6 ± 1.2, 53.5 ± 1.3, and 95.4 ± 1.4 kcal mol −1 respectively.

Polyglycolide–montmorillonite as a novel nanocomposite platform for biosensing applications

In catalytic biosensors, the immobilization of biomolecules in a suitable matrix is one of the vital parameters for obtaining improved systems. Clays, which are intercalated with various organic compounds, have a great tendency to develop biosensors with high stability, sensitivity and reproducibility. Herein, a polymer/clay nanocomposite based on natural silicate montmorilonite (Mt) and a biodegradable polymer polyglycolide (PGA) was prepared and characterized by FT-IR, thermogravimetric analysis, differential thermogravimetric analysis and X-ray diffraction. Then, the resulting matrix was used as a fixation matrix for pyranose oxidase (POx), which was selected as a model enzyme. The bioactive layer was fabricated by immobilization of POx on glassy carbon electrodes by means of PGA–Mt and bovine serum albumin. The POx biosensor revealed a good linear range from 0.01 to 0.5 mM glucose with a LOD of 1.2 μM. After the optimization of the working and preparation conditions, characterization studies were performed for glucose detection. Finally, the PGA–Mt/POx biosensor was confirmed to have detected glucose in beverages without needing any sample pre-treatment.

The Influence of Filler Component on Mechanical Properties and Thermal Analysis of PP-LDPE and PP-LDPE/DAP Ternary Composites

Composite material is a material system consisting of a mixture or combination of two or more micro-constituents mutually insoluble and differing in form and/or material composition. Particulate-filled thermoplastic composites have proved to be of significant commercial importance in recent years, as industrialists and technologists have sought to find new and cost-effective materials for specific applications (Shonaike & Advani, 2003; Ma et al., 2007). With addition of inorganic filler, various changes occur in the molecular and supermolecular structure of a thermoplastic resin. Composite properties depend on a variety of material-process variables (e.g., polymer matrix structure, filler content, chemical composition, surface activity, particle size and shape, compounding extruder design, mold design, and extruder-molding process conditions). Some changes may be latent or delayed (i.e., occurring later in the service life of the plastic part as a result of surrounding conditions). Reduction of molecular weight, crystal and spherulite size, and molecular mobility are among the most profound effects that solid filler has on the polymer matrix structure (Ayae & Takashi, 2004). The microstructure of the polymer–filler interphase is mirrored by the mechanical integrity of the molded part and long-term durability to extremes of surrounding temperatures and applied stresses. Calcium carbonate is very commonly used filler in the plastics industry. The incorporation of fillers such as calcium carbonate into thermoplastics is a common practice in the plastics industry, being used to reduce the production costs of molded products. Fillers are also used to modify the properties of plastics, such as the modulus and strength. High filler loadings, however, may adversely affect the processability, ductility, and strength of composites (Rai & Singh, 2003). Some polyolefins are prone to chain-scission reactions in the presence of free radicals. PP is degraded due to chain scission in β position to the macroradicals site, while PE is crosslinked, due to macroradical recombination (Braun et al., 1998). The use of organic

Characterization and dielectric properties of sodium fluoride doped talc

Abstract The purpose of this paper is to determine the effect of NaF and firing temperature on the dielectric properties (dielectric constant and dielectric loss) of talc, which is used in the electrical and electronic industries as a circuit element. A detailed characterization of the samples was made by XRD, FTIR, SEM and TG-DTG methods. Dielectric measurements were performed in the frequency range from 1 MHz to 80 MHz at room temperature. The dielectric constant value increased with an increase in firing temperature due to the removal of polarizable compounds from the talc structure. The higher dielectric constant values were obtained by addition of NaF. The dielectric loss of NaF doped talc decreased with the increase of firing temperature and increased with the increase of the amount of NaF.

Synthesis and radical polymerizations of acrylamides having Gabapentin moieties

Abstract The synthesis and radical polymerizations of several acrylamides having Gabapentin(GBP) moieties were examined. The monomers were prepared by the reactions of 1-aminomethyl-1-cyclohexane acetic acid salts with acryloyl chloride in the presence of triethylamine in moderate yields. Radical polymerizations of the monomers were carried out in the presence of AIBN (3 mol%) in Dimethyl formamide (DMF) with moderate yield. The thermal behavior of the polymers was investigated by thermo gravimetric analysis (TGA) and differential scanning calorimeter (DSC) to determine the thermal degradation pattern and glass transition temperature (Tg). The resulting polymers showed a thermal stability up to 400 °C. The glass transition temperatures of the polymers were found not to depend on the substituents of the GBP moieties. Nearly the same TG’s were observed for polymers. We found the molecular weights of the polymers to be between 20700 and 2300 g/mol. We obtained poly(HFCHA) as a water-soluble polymer. Poly(MFCHA), poly(EFCHA) and poly(PFCHA) were soluble in common solvents.

A Study on the Interaction Between 6-Methyl Purine and Cytosine by Means of Absorption and Fluorescence Emission Spectroscopy

Abstract The hydrogen bond formation between 6-methyl purine and cytosine has been studied at room temperature. The absorption and fluorescence emission spectra of 2.10−5μ 6-methyl purine solutions containing different amounts of cytosine in the range of 2.10−4−3, 5.10−4μ were investigated. The association constant for hyrogen bonded complex formation between 6-methyl purine and cytosine was found to be 1, 1.103 μ−1 from absorption difference spectra. The same association constant in the excited state was found to be 3, 9.103 μ−1 from fluorescence spectra.

Fluorescence titration of some purines determination of lowest excited-state ionization constants

Abstract Excited-state ionization equilibria of 6-methyl purine and xanthine were investigated in a wide range of pH. 6-Methyl purine is known to have two ionization equilibria in its ground-state. It was found that it had one more ionization equilibrium in strongly acidic region. In the excited state, four ionization equilibria were observed. The pK∗ values of three of them were determined by means of fluorescence titration. In the case of xanthine, there exist three ground-state equilibria. In the excited-state, four equilibria were observed. The pK∗ values of two of them were determined by means of fluorescence titration.