Chryssa Tzougraki

Development and application of suitable criteria for the evaluation of chemical representations in school textbooks

The study of Chemistry deals essentially with three types of chemical representations: macro, submicro, and symbolic. Research has consistently shown that students experience difficulties in understanding and interpreting the representations, in making translations between different types of representations, and in constructing them. In this study, we conducted a detailed review of existing presuppositions that define what Chemical Representations are to be included in school textbooks for the purpose of enhancing the student’s understanding of Chemistry. We then conducted a detailed analysis of the Chemical Representations included in five Chemistry textbooks. The detailed analysis revealed five criteria for the evaluation of chemical representation used in school textbooks. These criteria (C1-C5) are: (C1) the type of the representation; (C2) the interpretation of the surface features; (C3) their relationship to the text; (C4) the existence and the properties of a caption; (C5) the degree of correlation between the components comprising a multiple representation. The utility of the proposed criteria was then checked against a 10th-grade Greek chemistry textbook. The five criteria cover the basic elements required for a better utilization of chemical representations in the understanding of Chemistry. The five criteria can also be used for the analysis of existing school textbooks and as an authoring tool in designing new Chemistry textbooks.

Highly sensitive intramolecularly quenched fluorogenic substrates for renin based on the combination of L-2-amino-3-(7-methoxy-4-coumaryl)propionic acid with 2,4-dinitrophenyl groups at various positions.

The development of renin inhibitors for the treatment of hypertension requires highly sensitive substrates to evaluate potency and to characterize the mechanism of tight-binding inhibitors. A series of intramolecularly quenched fluorogenic renin substrates, based on the N-terminal tetradecapeptide sequence of human angiotensinogen (hTDP), was synthesized using a solid-phase technique. Incorporation of the fluorescent amino acid L-Amp [L-2-amino-3-(7-methoxy-4-coumaryl)propionic acid] and the DNP (2,4-dinitrophenyl) group at various positions resulted in >90% quenching efficiency and strong product fluorescence. Shortening the hTDP sequence to an octapeptide from histidine in P5 to histidine in P3 (substrate 3) resulted in an acceptable k(cat)/K(m) (41000 M(-1).s(-1)) and further systematic variation gave substrate 9, DNP-Lys-His-Pro-Phe-His-Leu-Val-Ile-His-L-Amp, with a k(cat)/K(m) value of 350000 M(-1).s(-1) and 94% quenching efficiency. The free side chain of lysine, replacing the isoleucine residue at P6 position in the angiotensinogen sequence, contributed to the increased value for k(cat). The pH dependence of k(cat)/K(m) for renin and substrate 9 showed that the optimal pH is at pH 6-7. It also showed two titrating groups on the acidic side of the pH optimum, and one titrating group with a pK(a) of 7.8 on the alkaline side. The combination of good kinetic and spectroscopic properties resulted in a >20-fold improvement in the sensitivity of renin assay, compared with the commercial substrate Arg-Glu(EDANS)-Ile-His-Pro-Phe-His-Leu-Val-Ile-His-Thr-Lys(DABCYL)-Arg [where EDANS is 5-[(2-aminoethyl)amino]naphthalene-1-sulphonic acid and DABCYL is 4-(4-dimethylaminophenylazo)benzoic acid] (k(cat)/K(m)=268000 M(-1) x s(-1), quenching efficiency <80%). The detection limit in a microplate renin assay was 60 pM, making substrate 9 well suited for the evaluation of inhibitors at picomolar concentrations.

Design and Development of a Bilingual Multimedia Educational Tool for Teaching Chemistry Concepts to Deaf Students in Greek Sign Language

In this paper the design and development of a multimedia system which serves as a bilingual chemistry educational tool for deaf students is presented. Details of the architecture of the tool, its functionality and formative evaluation results are also presented. Furthermore the process to arrive at the chemistry terminology in Greek Sign Language used throughout the tool is briefly described.

A general and direct method for the solid phase synthesis of intramolecular quenched fluorogenic protease substrates using a bifunctional coumarin derivative

A general method for the solid phase preparation offluorogenic peptide substrates or intramolecularly quenchedones (IQFS) is presented, using the highly fluorescentbifunctional coumarin derivative 7-amino-4-coumarinyl-acetic acid. The key feature of this method is theconjugation of H–Aca–OH through its carboxyl group on theresin, followed by the development of the peptide chainthrough its amino group, using standard Fmoc-derived solidphase peptide synthesis methodology. The 2,4-dinitrophenylgroup was used as quencher and introduced directly to theresin-bound peptides. The IQFSDnp–Lys–Pro–Ile–Cys–Phe–Ile–Lys–Leu–Aca–OH (2) andfour Dnp–X-Lys–Pro–Ile–Cys–Phe–Ile–Lys–Leu–Aca–OH (3–6), where X = Val, Lys, Ser and Glu at P6 position,potential substrates for cathepsin D, were synthesized forproving the utility of the method. The compoundsH–Ile–Lys–Leu–Aca–OH (7),H–Lys–Pro–Ile–Cys–Phe–Ile–Lys–Leu–Aca–OH (8),H–Leu–Aca–OH (9), Dnp–Leu–Aca–OH (10) and Dnp-Leu-OH (11) were also synthesized for comparisonpurposes. The fluorescence properties of compounds 9and 10 were measured.

Changes in visual/spatial and analytic strategy use in organic chemistry with the development of expertise

We present two studies that investigated the adoption of visual/spatial and analytic strategies by individuals at different levels of expertise in the area of organic chemistry, using the Visual Analytic Chemistry Task (VACT). The VACT allows the direct detection of analytic strategy use without drawing inferences about underlying mental processes. The first study examined the psychometric properties of the VACT and revealed a structure consistent with the hypothesis that it consists of two sub-scales: visual/spatial and analytic. The second study investigated the performance of 285 participants with various levels of expertise in organic chemistry on the VACT. The results showed that the adoption of analytic strategies in organic chemistry, and specifically in molecular structure, was difficult and was systematically used only by the more expert participants. The implications of this research for the teaching of chemistry are discussed.

‘CHEMICAL EDUCATION AND NEW EDUCATIONAL TECHNOLOGIES’: AN INTER-UNIVERSITY PROGRAM FOR GRADUATE STUDIES

In response to the general directive by the Greek Ministry of Education for the development of inter-university programs of graduate studies in Greece, the Chemistry Departments of the Universities of Athens, Thessaloniki and Ioannina, and the Department of Chemical Engineering of the National Technical University of Athens have initiated a program for graduate studies entitled Chemical Education and New Educational Technologies. The goal of the program is to provide scientific and educational training at graduate level to serving and prospective secondary chemistry teachers in Greece. For 1998-99 and for 1999-00 thirty-five and thirty-seven students respectively were selected and are attending the courses taught in Athens and in Thessaloniki. The two-year study leads to the masters degree, after which the students can continue for the doctors degree in any of the participating departments. During the first three semesters, every student has to attend taught courses, and to do practical work in science and in educational technology; in addition, in the second year he/she has to carry out a small research educational project. It is hoped that our students will be able to transfer the chemical knowledge in a more efficient way, taking advantage of (a) the guidelines offered by research in chemistry and science education and (b) the vast development of new educational technologies. (Chem. Educ. Res. Pract. Eur.: 2000, 1, 405-410)