The design and evaluation of two types of chemical sensor

During the course of this investigation it was discovered that functionalised Ruthenium tris(bipyridyl) complexes exhibit different chemical, spectroscopic and electrochemical properties to those of the parent compound. Furthermore, it was possible to develop 1,8-naphthalimide-based compounds that furnished strong 1:1 host:guest complexes with larger anions such as hydrogen pyrophosphate. This dissertation presents in investigation into the systhesis and analytical evaluation of two types of chemical sensors: chemiluminescent and fluorescent.

Some unusual applications of the `Error-bar` feature in Excel spreadsheets

This paper demonstrates how the "error-bar" feature can be used to extend the utility of "worldware" spreadsheet packages in producing high-quality graphs for university teaching and learning, and for research. To further utilize the advantages of spreadsheets in university education, this paper seeks to overcome some of the earlier reservations about the lack of scientific plotting capabilities of spreadsheet applications. Specific examples of educational material in the areas of enzyme kinetics, vibrational spectroscopy, vibronic spectroscopy, and mass spectrometry are discussed. It is argued that, where practical, university educators should use "worldware" packages to prepare teaching aids, since these would better prepare their students for future employment. The use of software features for purposes that were not envisioned by the programmers has additional educational benefits in fostering flexibility and innovation. Other graphing packages can also use the "error-bar" feature in a manner similar to that described here for Excel.

New light from an old reagent: chemiluminescence from the reaction of potassium permanganate with sodium borohydride

When aqueous sodium borohydride (50 mM) is added to a solution of potassium permanganate (1mM, in sodium hexametaphosphate) at acidic pH, bright red-orange emission is easily visible in a darkened room. This chemiluminescence emission is due to an excited state of manganese (II) that undergoes solution phase phosphorescence and provides an excellent opportunity for students to explore the relationship between the initial oxidation state of the manganese and the likelihood of luminescence. Not surprisingly Mn(VII), Mn(IV) and Mn(III) all give rise to chemiluminescence where as Mn(II) fails to react.

Influence of chemical oxidant on degradation of benzo[a]pyrene metabolites by the bacterium-Zoogloea sp.

It is neither comprehensive nor appropriate that the bioremediation of a benzo[a]pyrene (BaP)-contaminated environment be assessed only by its high degradation extent because its metabolites' chemical structures are similar to the parent compound and maybe equally toxic. Therefore, further degradation of BaP metabolites is significant. Three methods, combining the Zoogloea sp. with potassium permanganate, combining the Zoogloea sp. with H₂O₂, Zoogloea sp. alone, were investigated to degrade cis-BP4,5-dihydrodiol and cis-BP7,8-dihydrodiol, which are the metabolites of BaP formed by bacterium-Zoogloea sp. Optimum parameters of degradation in the best method are that: of the three methods, coupling the Zoogloea sp. and KMnO₄ is the best; compared with cis-BP7,8-dihydrodiol, cis-BP4,5-dihydrodiol is the more liable to be accumulated in pure cultures; the degradation effect of the two metabolites is optimal when the initial concentration of KMnO₄ in the cultures is 0.05%; initial concentration of cis-BP4,5-dihydrodiol and cis-BP7,8-dihydrodiol is 4 mg L⁻¹, 8 mg L⁻¹, respectively; cometabolic substance is salicylic acid or sodium succinate. The degradation extent of cis-BP4,5-dihydrodiol and cis-BP7,8-dihydrodiol using combining the Zoogloea sp. and KMnO₄ reach 76.1% and 85.9% after 12 days of cultivation, respectively, which were more than twice compared with conventional method.

Correct interpretation of chemical diagrams requires transforming from one level of representation to another

17 volunteer non-major chemistry students taking an introductory university chemistry course were interviewed about their understanding of a variety of chemical diagrams. All the students' interviewed appreciated that diagrams of laboratory equipment were useful to show how to set up laboratory equipment. However students' ability to explain specific diagrams at either the macroscopic or sub-microscopic level varied greatly. The results highlighted the poor level of understanding that some students had even after completing both exercises and experiments using the diagrams. The connection between the diagrams of the macroscopic level (equipment, chemicals), the sub- microscopic level (molecular) and the symbolic level (equations) was not always considered explicitly by students. The results indicate a need for chemical diagrams to be used carefully and more explicitly to ensure learner understanding. Correspondingly, students need to interpret visual chemical diagrams using meta-visualisation skills linking the various levels of representation, and appreciating the role of the diagrams in explanations need to be developed.

The division of labor, capital, communication technology and economic growth : the case of China 1952–99

The implications of the division of labor, capital, and technology for economic growth have long been a fundamental issue in development economics. This paper employs the bounds testing approach to cointegration to examine the relationship between the division of labor, capital accumulation, communication technology, and economic growth for China over the period 1952–99. We find that in the long run, capital stock and the division of labor both have statistically significant positive effects on growth, while in the short run the effects are not significantly positive. Telecommunication technology, rather surprisingly, has a statistically insignificant impact on growth both in the long run and in the short run. Our findings indicate that there exists a long run equilibrium relationship between capital and the division of labor on the one hand, and economic growth on the other, thereby lending support to the division of labor theory of growth.

The descriptive and explanatory nature of chemical diagrams does not guarantee understanding

Volunteer non-major chemistry students, taking an introductory university chemistry course (n= 17) were interviewed about their understanding of a variety of chemical diagrams. All the students’ interviewed appreciated that diagrams of laboratory equipment were useful to show how to set up laboratory equipment. However students’ ability to explain specific diagrams at either the macroscopic or sub-microscopic level varied greatly. The results highlighted the poor level of understanding that some students had even after completing both exercises and experiments using the diagrams. The connection between the diagrams of the macroscopic level (equipment), the sub-microscopic level (molecular) and the symbolic level (equations) was not always apparent to students. The results indicate a need for chemical diagrams to be used carefully and more explicitly to ensure the learner understanding.

What can student-generated diagrams tell us about their understanding of chemical equations?

Chemical equations are representations that use symbols to summarise the net changes occurring in a reaction whereas depictions such as drawings of the submicroscopic level provide representations of the chemical transformations. While the ability to balance and interpret chemical equations is key to understanding many concepts in chemistry, many undergraduate chemistry students struggle to master these skills. The equations contain a great deal of implicit information and novices may not be able to make the connection between the equation and the actual chemical transformations that are occurring. This paper reports on a study which used submicroscopic diagrams to probe students' understanding of chemical equations. Assessment tasks required students to interpret diagrams, construct diagrams and to relate diagrams to symbolic representations. The analysis showed that some students have misconceptions about the molecular nature and chemical formulae and could not distinguish between coefficients and subscripts when representing chemical formulae. While students were generally able to balance a chemical equation presented as a set of diagrams, a significant number could not generate the balanced equation based on a diagram of the progress of a reaction, The study has demonstrated the use of student-generated diagrams to provide insight into students' understandings of chemical equations.