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

What is the Effect of Case-Based Learning on the Academic Achievement of Students on the Topic of "Biochemical Oxygen Demand?"

WOS: 000501034400009The purpose of this study was to investigate the effect of the case-based learning (CBL) method used in "biochemical oxygen demand (BOD)," which is a topic taught in the environmental chemistry course, at Dokuz Eylul University, on the academic achievement and opinions of students. The research had a quasi-experimental design and the study group consisted of 4th and 5th grade students (N = 18) attending the Chemistry Teaching Program in a university in Izmir. The "Biochemical Oxygen Demand Achievement Test (BODAT)" and the structured interview form were used as data collection tools. The results of BODAT post-test showed the higher increase in the achievement scores of the experimental group may be an indication of the effectiveness of the CBL method in improving academic achievement in the relevant topic. In addition, the experimental and control group students had positive opinions regarding the method, the scenario, and the material. The students found the method, the scenario, and the material to be interesting, understandable/instructional, relatable with everyday life, suitable for the topic, and enhancing active participation

The effects of problem-based learning (PBL) on the academic achievement of students studying 'Electrochemistry'

WOS: 000393762500007This study investigates the effects of problem-based learning (PBL) on students' academic achievements in studying 'Electrochemistry' within a course on Analytical Chemistry. The research was of a pretest-posttest control group quasi-experimental design and it was conducted with second year students in the Chemistry Teaching Program at the Faculty of Education at Dokuz Eylul University. The topic was taught with PBL in the experimental group and with expository teaching strategies in the control group. The 'Chemistry achievement test (CAT)' was applied as the pre-test and post-test in both groups. Post-test scores from the CAT demonstrated that there was a significant difference between the academic achievements of the two groups in favour of the experimental group (U = 8.500, p < 0.05). After using PBL for a period, eleven open-ended questions related to the topic were asked to both groups. The results of these questions were categorized and the scores obtained from the categories were evaluated using content analysis. The results of the scores obtained from the open-ended questions showed that the students in the experimental group were able to make statements containing fewer misconceptions and also had a better understanding of this topic when compared to the students in the control group (U = 2.500, p < 0.05). The correlation between the scores in the CAT post-test and the scores obtained from the open-ended questions of the experimental and control groups was also examined. The Spearman correlation coefficients were found to be 0.907 and 0.595 for the experimental and the control group, respectively. This finding indicated that there was a positive and very high level of statistically significant correlation between the scores in the CAT post-test and the scores obtained from the open-ended questions of the students in the experimental group. Therefore this finding also supports the conclusion that the students in the experimental group were better able to understand the topic and its structure compared to the students in the control group. At the end of the application, the results of semi-structured interviews carried out showed that students in the experimental group had positive opinions regarding PBL

Development of a new biosensor for mediatorless voltammetric determination of hydrogen peroxide and its application in milk samples

WOS: 000266821100003A new biosensor for the voltammetric detection of hydrogen peroxide was developed based on immobilization of catalase on a clinoptilolite modified carbon paste electrode using bovine serum albumin and glutaraldehyde. The biosensor response was evaluated according to electrode composition, reaction time, solution pH and temperature. The voltammetric signals were linearly in proportion to H(2)O(2) concentration in the range 5.0 x 10(-6) - 1.0 x 10(-3) M with a correlation coefficient of 0.9975. The detection limit is 8.0 x 10(-7) M and the relative standard deviation for 4.0 x 10(-4) M hydrogen peroxide was 1.83% (n = 6). The biosensor exhibited high sensitivity, and it was determined that it could be used for more than 2 months. In addition, the biosensor was successfully applied for the determination of hydrogen peroxide in milk samples

Development of biosotption-based algal biosensor for Cu(II) using Tetraselmis chuii

WOS: 000251465000037A new biosorption-based biosensor using Tetraselmis chuii microalgae was developed for the voltammetric measurement of copper(II). Biosensor was prepared by incorporating non-living biomass in carbon paste. T chuii incorporated in carbon paste electrodes (CPE) in weight percentages ranging from 2.5 to 20 accumulate copper(II) from solution through passive adsorption. Copper(II) was accumulated, at open circuit, on the algal biosensor and the voltammetric measurements were carried out by differential pulse cathodic stripping voltammetry. The biosensor performance was optimized with respect to the operating conditions. Under the optimal conditions, a detection limit of 4.6 x 10(-10) M was obtained with a good precision (R.S.D. = 3.4%, n = 6). The cathodic peak current was linear with concentration in the range of 5.0 x 10(-8)-1.0 X 10(-6) M (r=0.9981). The developed biosensor was also applied for the determination of copper(II) in real sample. Such an excellent performance of the algal biosensor toward copper(II), represents a very good alternative for developing other sensors. (c) 2007 Elsevier B.V. All rights reserved