DIPL 6004 Peacemaking and Peacekeeping

This course examines theories and research concerning the nature and causes of conflict at both the domestic and international levels, as well as methods for avoiding, managing or resolving such conflicts. It surveys theoretical frameworks from different disciplines. It would ground students the basic concepts of conflict resolution and skills of diagnosing social conflict. A second portion of the class focuses on the practice of conflict resolution and the connection between conflict analysis and intervention. This course will include a blend of lectures, class discussions, individual and group exercises, and simulation role plays

Chitosan based Butyrylcholinesterase Biosensor for the Pesticide Detection

The increasing concern for ground water pollution, due to the use of pesticides in agriculture, requires a strong effort in order to detect pollutants with reliable, economical and rapid methods; some pollutants like pesticides and heavy metals, infact, are very dangerous for human health. Pesticides are highly toxic compounds and some of them are powerfull inhibitors of enzymes involved in nerve functions. It is true that they show low environmental persistence but they have acut toxicity and therefore, there is a demand for fast screening methods for low concentrations of these pollutants. Detection methods currently used (LC, GC-MS) are not suitable as rapid screening methods, as they are time consuming and provide only discontinuous analysis. In this study, our goal was to develop a rapid and cheaper method for pesticide analysis. It is based on the potentiometric determination of the inhibiting properties of the pesticides on the cholinesterase activity. The enzyme butyrylcholinesterase is immobilized on the surface of the pH-electrode by using chitosan membrane, then the measuring conditions (pH, temperature, ionic strenght) were optimized. On the other hand, organic phase stabilitiy of the enzyme electrode was also tested. A temperature of 25 oC and pH 8.5 were found to be optimum conditions. All measurements were carried out 2.5 mM borate buffer (pH 8.5) at 25 oC. Furthermore, dependence of enzyme inhibition of the pesticide concentration and the regeneration conditions of inhibitted enzyme were achieved

A Lipoxygenase Sensor for Essential Fatty Acid (EFA) Determination

The essential fatty acids (EFAs) are a group of 12 compounds, but linoleic acid and a-linolenic acid are the only EFAs which are found in the diet, particularly in vegetable oils, in some abundance. The other on EFAs are either metabolic products of linoleic and a-linolenic acids or are found in the diet especially in marine foods, considerebly smaller amounts. The steadily growing knowledge about the correlation between the fatty acid composition of the diet and clinical disorders leads to a growing demand for a rapid and easy to use analytical device for fatty acid determination in foods. Up to date, the fatty acid composition of fats and oils is determined mainly by gas chromatography (GC), although GC is well established in lipid analysis and offers high sensitivities, it is still time consuming and laborious . In this study, we describe the development of enzyme sensors for the determination of w-3 and w-6 fatty acis from the mixture of EFAs. Since linoleic and a-linolenic acids show differences in first and second oxygenation activities, it is possible to analyse each of them in EFAs mixture. Lipoxygenases in general catalyse the oxygenation of polyunsaturated fatty acids containing a cis, cis-1,4-pentadiene system by molecular oxygen. The oxygen consumption due to the lipoxygenase catalysed oxygenation of EFAs monitored amperometrically. Lipoxygenase was immobilized on the surface of oxygen electrode by using different membrane systems. Each systems were compared with regard to linear ranges of the calibration plots, sensitivities, detection limits. Furthermore, optimization of working conditions (pH, temperature etc.) and stability tests were also studied

The Investigation of Electrochemical Behaviour of NADH with TBO at a Glassy Carbon Electrode

Electrochemical oxidation studies of NADH with different mediators have been made recently. It was shown that the reduction of NAD+ is more difficult than the oxidation of NADH. On the other hand, regenaration of some mediator systems which are immobilised on the same electrode surface takes a long time2. Therefore, the study of electrochemical behaviour of different mediator and NADH at a bare glassy carbon electrode will become a base for other relevant studies. In this study, electrochemical behaviour of TBO with NADH is investigated by differential puls and cyclic voltammetry and the influence of the temperature, different buffer systems, pH range and electrolyte type was optimised

Development of an Alcohol Dehydrogenase Biosensor for Ethanol Determination with Toluidine Blue O Covalently Attached to a Cellulose Acetate Modified Electrode

In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetric sensor for the ethanol determination. In order to fabricate the biosensor, a new electrode matrix containing insoluble Toluidine Blue O (TBO) was obtained from the process, and enzyme/coenzyme was combined on the biosensor surface. The influence of various experimental conditions was examined for the characterization of the optimum analytical performance. The developed biosensor exhibited sensitive and selective determination of ethanol and showed a linear response between 1 × 10−5 M and 4 × 10−4 M ethanol. A detection limit calculated as three times the signal-to-noise ratio was 5.0 × 10−6 M. At the end of the 20th day, the biosensor still retained 50% of its initial activity

Improving the stability of cellulase by immobilization on modified polyvinyl alcohol coated chitosan beads

WOS: 000244838400002The application of cellulases in various industries demands highly stable enzymes, able to perform at extreme pH values and temperatures. In this study, improving the stability of the acid cellulase in the neutral pH range was aimed. For this purpose, modification planned to be done on polyvinyl alcohol (PVA) by maleic anhydride in contrast to many studies in which enzyme was modified. The chitosan beads were coated with polyanionic modified PVA and cellulase was immobilized on the modified PVA coated chitosan beads. As a result of this modification, the pH optimum of enzyme shifted from pH 4.0 to 7.0 and the immobilized cellulase beads showed better pH stability than free enzyme at neutral pH range. The activity yield of the immobilized cellulase was found to be as 87%, and it was found no change of the optimum temperature after immobilization. (c) 2006 Elsevier B.V. All rights reserved

Kinetic properties of alphaalpha-D-galactosidase from watermelon (Citrullus vulgaris)

The kinetic properties of $\alpha$-D-galactosidase purified from watermelon (Citrullus vulgaris) were studied. Kinetic parameters were determined by using raffinose and p-nitrophenyl-$\alpha$-D-galactopyranoside as natural and synthetic substrates, respectively. The Km and Vmax values were 9.1x$10^{-1}$ mM and 7.14x$10^{-2}$ p.rnolmin-1 for p-nitrophenyl-$\alpha$-D-galactopyranoside and 7.1x$10^{-2}$ mM and 2.9x$10^{-3}$ $\mu molmin^{-1}$ for raffinose. The inhibition kinetics of D-galactose on the enzyme was also investigated. The type of inhibition caused by D-galactose was found as competitive.Karpuzdan (Citrullus vulgaris) saflaştırılan $\alpha$-D-galaktosidazın kinetik özellikleri incelendi. Kinetik parametreler, doğal ve sentetik substrat olarak rafinoz ve p-nitrofenil-$\alpha$-D-galaktopiranozid kullanılarak belirlendi. $K_m$ ve $V_ {max}$ değerleri sırasıyla p-nitrofenil-$\alpha$-D-galaktopiranozid için 9,1x$10^{-1}$ mM ve 7,14x$10^{-2}$ $\mu molmin^{-1}$ ve rafinoz için 7,1x$10^{-2}$ ve 2,9x$10^{-3}$ $\mu molmin^{-1}$ olarak hesaplandı. Ayrıca D-galaktozun enzim üzerine olan inhibisyon kinetikleri araştırıldı. D-galaktozun neden olduğu inhibisyon tipi kompetitif olarak bulundu