Yeliz Yildirim

Combustion behavior of different kinds of torrefied biomass and their blends with lignite.

In this study, the combustion behavior of different kinds of torrefied biomass (lignocellulosic and animal wastes) and their blends with lignite was investigated via non-isothermal thermogravimetric method under air atmosphere. For comparison, combustion characteristics of raw biomasses were also determined. Torrefaction process improved the reactivity of char combustion step of biomasses. Characteristic combustion parameters for blends showed non-additivity behavior. It was found that the mixture of torrefied biomasses and lignite at a ratio of 1:1 had a lower ignition and burnout temperature than the coal-only sample. Although no interactions were observed between the lignite and torrefied biomass at initial step of combustion, a certain degree of interaction between the components occurred at char combustion step. Kinetic parameters of combustion were calculated by using the Coats Redfern model. Overall, this study showed that poultry litters can be used as a substitute fuel in coal/biomass co-firing systems by blending with lignocellulosic biomass.

Self-radioiodination of iodogen.

Iodogen (1,3,4,6-tetrachloro-3alpha,6alpha-diphenylglucoluril) is commonly used for the radioiodination of proteins as an oxidative agent. The oxidative character of iodogen is not clear, but the two carbonyl groups in its structure probably have an essential role in its oxidizing character. In this study, the self-radioiodination of iodogen has been examined. It was observed that about 10-20% of the initial iodine radioactivity was consumed for the self-radioiodination of iodogen itself. On the other hand, the radioiodinated iodogen removed by ethyl alcohol from the iodogen-coated tubes showed clearly that no thyroid uptake was observed and that it was rapidly cleared out from the whole body of a rabbit administered with the radioiodinated iodogen by injection via the ear vein.

Metabolic comparison of radiolabeled aniline- and phenol-phthaleins with 131I

The metabolic comparison of aniline- and phenol-phthaleins radiolabeled with (131)I ((131)I-APH and (131)I-PPH, respectively) has been investigated in this study. To compare the metabolic behavior of these phthaleins and their glucuronide conjugates radiolabeled with (131)I, scintigraphic and biodistributional techniques were applied using male Albino rabbits. The results obtained have shown that these compounds were successfully radioiodinated with a radioiodination yield of about 100%. Maximum uptakes of (131)I-APH and (131)I-PPH, which were metabolized as N- and O-glucuronides, were observed within 2 h in the bladder and in the small intestine, respectively. In the case of verification of considerably up taking of these compounds also by tumors developed in the small intestine and in the bladder tissues, these results can be expected to be encouraging to test these compounds, which will be radiolabeled with other radioiodines such as (125)I, (123)I and (124)I as imaging and therapeutic agents in nuclear medical applications.

Radioiodination and preliminary biological tests of aniline-mustard and its glucuronide conjugate as a potential anticancer prodrug

Aniline-mustard and its glucuronide conjugate were radioiodinated with 131I. The preliminary dynamic tests were carried out on rabbits. The scintigrams showed clearly that the glucuronide conjugate of aniline-mustard was very quickly cleared from the metabolism, accumulating in the bladder in about 15 minutes. The clearance time of radioiodinated aniline-mustard-glucuronide was considerably longer (about 45 min.). The results obtained from the biodistributional studies have represented interesting differences between the metabolic details of radioiodinated compounds, and indicated that the glucuronide conjugate of aniline-mustard may be a promising radioiodinated prodrug, if verification of its selective accumulation in some kinds of tumor cells can be obtained.

Transfer of orally administrated iodine-131 into chicken eggs

Radioactive iodine-131 as both as free iodide (Na131I) and covalently bound to aniline (aniline-131I) was added to the drinking water of two Leghorn laying hens as a single dose and also as a cumulative dose over 1 week. The radioactivity of the principal parts of the eggs, i.e. shell, white, and yolk, was measured, and the radioactivity levels per gram material, and percent of the total radioactivity were calculated. The radioactivity measurements were continued for 1 month following the administration of 131I. In the case of the single dose administration, the results obtained showed that about 15% of the total radioactivity administered as Na131I was transported into the egg structure; compared to only about 1% for aniline-131I. After cumulative administration, about 15% of the total administered radioactivity was transported into the egg structure with both forms of 131I. This was probably because of metabolic cleavage of iodine bonds in the labeled aniline molecules during the longer period of exposure. These results also showed considerable accumulation of 131I in the egg yolks. In the case of the single dose administration, 131I can be detected in eggs up to about 20 days after administration, and up to about 30 days, in the case of the cumulative administration over 1 week.

New copolymer of acrylamide with allyl methacrylate and its capacity for the removal of azo dyes

The copolymerization reactions of Acrylamide (AA) with the different mole ratios of allyl methacrylate (AMA) such as 25/75, 50/50 and 75/25 were studied by radical polymerization under argon atmosphere using 2,2’-Azobis (isobutyronitri1e) (AIBN) as initiator. The copolymers were characterized with Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TG). FTIR spectra showed that the C=O, C-N and N-H groups in copolymers remained during the copolymerization. It is concluded from the thermograms that Poly(AA-co-AMA) copolymers which contained different ratios of monomer and comonomer exhibit similar thermal behavior. Adsorption capacity, kinetic and isotherm studies of Direct Brown 2 onto the copolymers have been evaluated. Different factors such as the monomer ratio, pH, initial dye concentration, copolymer dosage and contact time affecting the removal process were studied. It was found that the adsorption process agreed with the Freundlich and Dubinin-Raduskevich model and the adsorption of Direct Brown 2 depended on the acrylamide content and pH of the solution. The standard Gibb’s free energy was determined as - 14.7 kJ/mol, which means that adsorption occurred spontaneously and the process is feasible. Increasing the acrylamide content led to increased adsorption of Direct Brown 2 on the copolymer. Moreover, adsorption kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. These results show that Poly(AA-co-AMA) can be used as adsorbent for water pollutants such as Direct Brown 2 and has potential applications in related industrial and environmental areas.

Structural changes in Poly(lactic acid)–zeolite nanocomposites exposed to 60Co gamma rays

ABSTRACT Poly(lactic acid) (PLA) nanocomposites containing 3%, 5% and 7% zeolite used in the present research study were prepared by solution casting. The PLA nanocomposites were structurally characterized by Scanning Electron Microscopy and Fourier-transform infrared spectroscopy. The effects of the gamma radiation at the absorbed doses of 10, 15 and 20 kGy on the structures and thermal properties of the nanocomposites were investigated in a tetrahydrofuran solvent. Thermodecomposition tests and analyses were carried within 30–500°C range at the rate of 10°C min−1 by thermogravimetric analysis (TG). The activation energies for thermal degradation of the nanocomposites were calculated from their TG data by Flynn–Wall–Ozawa method. The G values of the nanocomposites were calculated based on molecular weights which were measured by means of gel permeation chromatography before and after the gamma irradiation. The Ea and molecular weight results showed that addition of zeolite to the PLA affected the radiation resistance of the polymer.

The Synthesis of Allyl Glycidyl Ether Copolymers and Their Thermokinetic Analysis

Abstract The copolymerization reactions of allyl glycidyl ether (AGE) by radicalic polymerization under argon atmosphere using benzoyl peroxide (BPO) as an initiator with the comonomers of allyl methacrylate (AMA) and methyl methacrylate (MMA) were studied. The synthesized copolymers were characterized by nuclear magnetic resonance ( 1 H-NMR), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TG). FTIR and 1 H NMR spectra showed that the pendant epoxy groups in copolymers remained throughout the copolymerization of AGE. The apparent activation energies for thermal degradation of the copolymers were calculated from their TG data by using Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Coats-Redfern methods. The kinetic parameters such as pre-exponential factor, Gibbs energy, enthalpy and entropy were also calculated by Coats-Redfern method. The activation energies calculated by KAS method for Poly(AGE -co- AMA) and Poly(AGE -co- MMA) were found to be 292±10 kJ/mol and 175±27 kJ/mol for the first stage, and 252±74 kJ/mol and 232±32 kJ/mol for the second, respectively while they were 361±1 kJ/mol and 249±61 kJ/mol for Poly(AGE -co- AMA) and 136±24 kJ/mol and 278±18 kJ/mol for Poly(AGE -co- MMA) by FWO method. The most likely mechanisms of the main degradation stages were determined as F 3 model for Poly(AGE -co- AMA) and Poly(AGE -co- MMA). Thus, it is concluded that the thermal degradations of Poly(AGE -co- AMA) and Poly(AGE -co- MMA) copolymers exhibit similar behavior. Keywords: Thermal degradation, allyl glycidyl ether, allyl methacrylate, methyl methacrylate