The modelling ability of non-major chemistry students and their understanding of the sub-microscopic level

This case study examined the ability of three first year non-major chemistry students to understand chemical concepts according to Johnstone’s three levels of chemical representations of matter. Students’ background knowledge in chemistry proved to be a powerful factor in their understanding of the submicroscopic level. The results show that modelling ability is not necessarily innate, but it is a skill to be learnt. Each of the students’ modelling abilities with chemical representations improved with instruction and practice. Generally, as modelling skills improved so did students’ understanding of the relevant chemical concept. Modelling ability is described according to Grosslight et al.’s three–tiered level and the ability to traverse the three levels of chemical representation of matter.

Linking the macroscopic and sub-microscopic levels : diagrams

Explanations of chemical phenomena are nearly always focused at the sub-micro level, a level that cannot be observed, yet are normally provided with diagrams at the symbolic level. These diagrams represent the macro and sub-micro levels of matter. The connections between the macro level and the diagrams of the sub-micro level are not always apparent to students, indicating a need for chemical diagrams to be used carefully and explicitly. Having students draw and annotate chemical diagrams representing chemical phenomena at the sub-micro level can provide some insight into their understanding of chemistry at the macro level. Misinterpretation of diagrams can occur when the representations are not understood, when links are not made between the macro and sub-micro levels, or when the diagram is unfamiliar. Responding to these difficulties, strategies based on research and our experiences of teaching with diagrams are suggested for the choice and use of chemical diagrams depicting the sub-micro level in the teaching and learning of chemistry. These strategies provide opportunities for learners to construct acceptable personal mental models of the sub-micro level.

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 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.

The development of theoretical frameworks for understanding the learning of chemistry

Chemistry has unique characteristics that make it a difficult subject to understand including the abstract concepts, the three levels of representation of matter – the macroscopic level, the sub-microscopic level and the symbolic level, and the complexities concerning the representational and theoretical qualities and the reality of each level. Drawing on data from a study with first year university students learning introductory chemistry, this chapter looks at how these students’ understandings of the characteristics of chemistry influence the way they understand and learn chemistry. Two theoretical frameworks to describe how chemical concepts can be presented and understood are developed based on the research data: the expanding triangle and the rising iceberg. The aim of the frameworks are to further develop the ways of thinking about how students learn chemistry thereby developing a chemical epistemology – that is, an understanding of the knowledge of how chemical ideas are built and an understanding of the way of knowing about chemical processes. These two frameworks are proposed as useful tools for chemistry educators to better understand students learning, linking chemical education research to practice so as to inform pedagogical content knowledge. Chemical education research can be theoretical and is sometimes criticised for not impacting on teachers practice, so the pedagogy of chemistry teachers is discussed with the aim of exploring ways the two frameworks can be useful in developing teachers’ professional understandings of learning and teaching chemistry to promote changes in their practice and support student understandings.

Towards elucidating microscopic structural changes in Li-ion conductors Li1+yTi2–yAly[PO4 ]3 and Li1+yTi2–yAly[PO4 ]3–x [MO4 ]x(M=V and Nb) : X-ray and27Al and31P NMR studies

A combination of X-ray powder diffraction (XRD) and nuclear magnetic resonance (NMR) studies has demonstrated that attempted substitutions of Al, V and Nb into the framework of LiTi₂(PO₄)₃ yield several impurity phases in addition to direct substitutions of Al into Ti and V, Nb into P sites. Direct substitutions were confirmed by changes in the unit cell dimensions as indicated by the peak shifts observed in the X-ray diffractographs and by analyses of the ²⁷Al and ³¹P magic angle spinning (MAS) spectra. A major impurity phase was identified as AlPO₄ (found in at least two polymorphs) and the amount present increases with increasing Al additions. The formation of AlPO₄ appeared to be enhanced by further V but suppressed by Nb substitution. These results suggest that the presence of AlPO₄ , together with the non-stoichiometric modified LTP, may be the cause for the observed densification of this material upon sintering and the increased ionic conductivity.

An intelligent decision support system for leukaemia diagnosis using microscopic blood images

This research proposes an intelligent decision support system for acute lymphoblastic leukaemia diagnosis from microscopic blood images. A novel clustering algorithm with stimulating discriminant measures (SDM) of both within- and between-cluster scatter variances is proposed to produce robust segmentation of nucleus and cytoplasm of lymphocytes/lymphoblasts. Specifically, the proposed between-cluster evaluation is formulated based on the trade-off of several between-cluster measures of well-known feature extraction methods. The SDM measures are used in conjuction with Genetic Algorithm for clustering nucleus, cytoplasm, and background regions. Subsequently, a total of eighty features consisting of shape, texture, and colour information of the nucleus and cytoplasm sub-images are extracted. A number of classifiers (multi-layer perceptron, Support Vector Machine (SVM) and Dempster-Shafer ensemble) are employed for lymphocyte/lymphoblast classification. Evaluated with the ALL-IDB2 database, the proposed SDM-based clustering overcomes the shortcomings of Fuzzy C-means which focuses purely on within-cluster scatter variance. It also outperforms Linear Discriminant Analysis and Fuzzy Compactness and Separation for nucleus-cytoplasm separation. The overall system achieves superior recognition rates of 96.72% and 96.67% accuracies using bootstrapping and 10-fold cross validation with Dempster-Shafer and SVM, respectively. The results also compare favourably with those reported in the literature, indicating the usefulness of the proposed SDM-based clustering method.

Post-migration food habits of sub-Saharan migrants in Victoria: a cross-sectional study

Objective: (i) To describe sub-Saharan African (SSA) post-migration food habits and eating patterns; and (ii) to examine how the food habits of SSA households in Victoria reflect post-migration acculturation.
Design: A cross-sectional survey using a snowball sampling technique. Data on food habits and eating patterns were obtained using semi-structured, face-to-face interviews from November 2001 to April 2002.
Subjects: A total of 139 households of demographically diverse recent migrants from across sub-Saharan Africa.
Setting: Melbourne metropolitan and Melbourne fringes.
Analysis: Data were summarised using descriptive statistics.
Results: SSA migrants and refugees indicated dietary acculturation characterised by three processes: substitution, supplementation and modification of recipes. They experienced difficulty locating their traditional foods, in particular, African vegetables (34.2%), unprocessed maize meal (29.1%), camel milk (23.1%) and maize grain (13.7%). The new foods adopted since arrival were pizza, breakfast cereals and fast foods, but also included new fruits and vegetables. Takeaway food such as Pizza Hut or McDonalds featured prominently in the SSA post-migration diet. Reasons for eating out were favourite food (48.3%), routine family outing (38.3%), special occasion (33.3%) and no time to cook (25%). A significant change in meal pattern was the inclusion of breakfast, although 21% reported skipping breakfast.
Conclusion: Many of the observed dietary changes were not consistent with good health and may predispose this population to rapid weight gain and chronic disease. Rapid modernisation and the Anglo-Australian culture interact in a complex way with traditional eating and socialisation practices of SSA migrants. Understanding these forces can allow effective health promotion and community development strategies to be developed for the future health of SSA migrants and their communities.

Obesity and undernutrition in sub-Saharan African immigrant and refugee children in Victoria, Australia

The study assessed the anthropometric status of 337 sub-Saharan African children aged between 3-12 years who migrated to Australia. These children were selected using a snowball sampling method stratified by age, gender and region of origin. The prevalence rates for overweight and obesity were 18.4% (95%CI: 14 - 23%) and 8.6% (95%CI: 6% -12%) respectively. The prevalence rates for the indicators of undernutrition were: wasting 4.3% (95%CI: 1.6%-9.1%), underweight 1.2% (95%CI: 0.3%-3.0%), and stunting 0.3 (95%CI: 0.0%-1.6%). Higher prevalence of overweight/obesity was associated with lower household income level, fewer siblings, lower birth weight, western African background, and single parent households (after controlling for demographic and socio-economic factors). Higher prevalence rates for underweight and wasting were associated with lower household income and shorter lengths of stay in Australia respectively. No effect was found for child's age, gender, parental education and occupation for both obesity and undernutrition indices. In conclusion, obesity and overweight are very prevalent in SSA migrant children and undernutrition, especially wasting, was also not uncommon in this target group.

Fat, rich and beautiful: changing socio-cultural paradigms associated with obesity risk, nutritional status and refugee children from sub-Saharan Africa

There has been an increase in Australia's intake of refugees and migrants from sub-Saharan Africa over the last two decades. These refugees have been exposed to nutritional risks prior to migration, which, together with changes associated with acculturation, impact on their health and nutritional status post-migration. However, there is a paucity of data in Australia that has examined the health and nutritional status of this ethnic minority in Australia. Despite basic research assessing the nutritional status of children, none have specifically concentrated on the health and nutritional situation of sub-Saharan refugee children. In the absence of such studies, this paper explores issues relating to obesity in sub-Saharan African refugee children within a cultural and public health framework. We begin by outlining the history of obesity and its cultural meaning. We then move to a consideration of predisposing factors for obesity and how these factors translate into obesity risk contexts of sub-Saharan refugees post-migration. We argue there are a number of key challenges related to culture and the relationship between socio-economic factors post-migration that require addressing by health professionals, dieticians and health educators to ensure the delivery of successful health outcomes.

Microscopic nature and elemental composition of brown coal fly ash particles from a large coal fired power station

In this study, Australian brown coal fly ash particles have been collected from power station and analysed by scanning electron microscopy to obtain morphological information and elemental composition of individual particles. The most common particles found to be the irregular shape particle aggregates. Other shapes include ball shape with smooth surface and with some attachments; and crystal shape fine particles. The X-ray spectra of each fly ash particle revealed five groups of elemental composition, they are Si-rich particles; Ca-rich particles; Fe-rich particles; particles with Mg-Ca Matrix and particles with Si-Ca matrix. A particle sire distribution analysis has been conducted using particle size analyser and found to have a mean particle size of 21fim. The sample then was separated into fine and coarse fractions using aerodynamic classifier, and the elemental composition of both fractions were determined by ICP-AES. Borate fusion and acid dissolution method was used for sample preparation. It is found that some environmental sensitive elements such as Zn, Pb, Ni, K and Cu are enriched in fine fly ash particles. Ca has much higher contents in fine particles as well. Si and Mg have higher concentrations in coarse particles.

Guanxi in a sub-national cross-cultural setting

This paper explores whether Chinese relationship building, Guanxi, is effective in crosscultural sub-national relationships. Derived from research into Sino-Australian Sister City Type Relationships and using material gathered through interviews in China and Australia, a modified Institutional Guanxi conceptual model has been developed. Some propositions are developed to link the components of the Guanxi conceptual model. Different methodologies are explored to determine the most effective way to test the hypotheses in a cross-cultural environment, and future research is outlined.

A computational framework for nucleic acid sub-sequence identification

Identification of nucleic acid sub-sequences within larger background sequences is a fundamental need of the biology community. The applicability correlates to research studies looking for homologous regions, diagnostic purposes and many other related activities. This paper serves to detail the approaches taken leading to sub-sequence identification through the use of hidden Markov models and associated scoring optimisations. The investigation of techniques for locating conserved basal promoter elements correlates to promoter thus gene identification techniques. The case study centred on the TATA box basal promoter element, as such the background is a gene sequence with the TATA box the target. Outcomes from the research conducted, highlights generic algorithms for sub-sequence identification, as such these generic processes can be transposed to any case study where identification of a target sequence is required. Paths extending from the work conducted in this investigation have led to the development of a generic framework for the future applicability of hidden Markov models to biological sequence analysis in a computational context.