A reconstruction of development of the periodic table based on history and philosophy of science and its implications for general chemistry textbooks

The objectives of this study are: (a) elaboration of a history and philosophy of science (HPS) framework based on a reconstruction of the development of the periodic table; (b) formulation of seven criteria based on the framework; and (c) evaluation of 57 freshman college‐level general chemistry textbooks with respect to the presentation of the periodic table. The historical reconstruction of the periodic table showed that the periodicity of the elements could be construed as an inductive generalization or as a function of the atomic theory. There is considerable controversy with respect to the nature of Mendeleev's contribution, and various alternatives are discussed: ordered domain; empirical law; and a theory with limited explanatory power. Accommodation of the elements according to their physicochemical properties is considered to be the major contribution of the periodic table by all textbooks, followed by contrapredictions of previously unknown elements (30 textbooks), and novel predictions (corrections of atomic mass) of known elements (10 textbooks). The relative importance of accommodation and prediction within an HPS framework is generally ignored. Few textbooks have attempted to explore the possible cause of periodicity in the table and very few textbooks have explored the nature of Mendeleev's contribution. The development of the periodic table as a sequence of heuristic principles in the form of a convincing argument has been ignored. The textbook approach of emphasizing that the development of the periodic table was an inductive generalization, and that Mendeleev had no model or theory, does not facilitate the spirit of critical inquiry that led the scientists to grapple with alternative interpretations, conflicts, and controversies. It is concluded that the development of the periodic table went through a continual critical appraisal (conflict and controversy), in which scientists presented various tentative theoretical ideas to understand the observed phenomena. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 42: 84–111, 2005     

Chip morphology predictions while machining hardened tool steel using finite element and smoothed particles hydrodynamics methods

Chip morphology predictions in metal cutting have always been challenging because of the complexity of the various multiphysical phenomena that occur across the tool-chip interface. An accurate prediction of chip morphology is a key factor in the assessment of a particular machining operation with regard to both tool performance and workpiece quality. Although finite element (FE) models are being developed over the last two decades, their capabilities in modeling correct material flow around the tool tip with shear localization are very limited. FE models with an arbitrary Lagrangian Eulerian (ALE) approach are able to simulate correct material flow around the tool tip. However, these models are unable to predict any shear localization based on material flow criteria. On the other hand, FE models with a Lagrangian formulation can simulate shear localization in the chip segments; they need to make use of a mesh-based chip separation criterion that significantly affects material flow around the tool tip. In this study a mesh-free method viz. smoothed particles hydrodynamics (SPH) is implemented to simulate shear localization in the chip while machining hardened steel. Unlike other SPH models developed by some researchers, this model is based on a renormalized formulation that can consider frictional stresses along the tool-chip interface giving a realistic chip shape and material flow. SPH models with different cutting parameters are compared with the traditional FE models and it has been found that the SPH models are good for predicting shear localized chips and do not need any geometric or mesh-based chip separation criteria.     

A comparative study of conventional and supercritical fluid extraction methods for the recovery of secondary metabolites from <Emphasis Type="Italic">Syzygium campanulatum</Emphasis> Korth

Syzygium campanulatum Korth is a plant, which is a rich source of secondary metabolites (especially flavanones, chalcone, and triterpenoids). In our present study, three conventional solvent extraction (CSE) techniques and supercritical fluid extraction (SFE) techniques were performed to achieve a maximum recovery of two flavanones, chalcone, and two triterpenoids from S. campanulatum leaves. Furthermore, a Box-Behnken design was constructed for the SFE technique using pressure, temperature, and particle size as independent variables, and yields of crude extract, individual and total secondary metabolites as the dependent variables. In the CSE procedure, twenty extracts were produced using ten different solvents and three techniques (maceration, soxhletion, and reflux). An enriched extract of five secondary metabolites was collected using n-hexane:methanol (1:1) soxhletion. Using food-grade ethanol as a modifier, the SFE methods produced a higher recovery (25.5%?84.9%) of selected secondary metabolites as compared to the CSE techniques (0.92%?66.00%).     

Phytoremediation of heavy metal polluted soils and water：Progresses and perspectives

Environmental pollution affects the quality of pedosphere, hydrosphere, atmosphere, lithosphere and biosphere. Great efforts have been made in the last two decades to reduce pollution sources and remedy the polluted soil and water resources. Phytoremediation, being more cost-effective and fewer side effects than physical and chemical approaches, has gained increasing popularity in both academic and practical circles. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. It is also expected that recent advances in biotechnology will play a promising role in the development of new hyperaccumulators by transferring metal hyperaccumulating genes from low biomass wild species to the higher biomass producing cultivated species in the times to come. This paper attempted to provide a brief review on recent progresses in research and practical applications of phytoremediation for soil and water resources. Project supported by the Higher Education Commission, Government of Pakistan for the faculty training under the R & D Project “Strengthening Department of Soil Science and Soil and Water Conservation” at the University of Florida, USA, a grant from the St. Lucie River Water Initiative (SFWMD contract No. OT060162), USA, in part, and the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0536), China     

Cognitive conflict as a teaching strategy in solving chemistry problems: A dialectic–constructivist perspective

The main objective of this study was to evaluate the effect of teaching experiments within a dialectic-constructivist framework based on the following considerations: (a) Cognitive conflicts used in the teaching experiments must be based on problem-solving strategies that students find relatively convincing: (b) after having generated a cognitive conflict, it is essential that the students be provided with an experience that could facilitate the resolution of the conflict; and (c) the teaching strategy developed is used by an interactive constructivist approach within an intact classroom. The study was based on two sections of freshman students who had registered for Chemistry I at the Universidad de Oriente, Venezuela. One of the sections was randomly designated as the control group and the other as the experimental group. To introduce cognitive conflict, the experimental group was exposed to two teaching experiments dealing with stoichiometry problems based on the concept of limiting reagent. Students in the control group were exposed to the same problems—however, without the cognitive conflict teaching experiments format. To evaluate the effect of the teaching experiments, both groups were evaluated on five different problems at different intervals during the semester, referred to as posttests. All posttests formed part of the regular evaluation of the students. Results obtained show the advantage of the experimental group on four of the posttests. It is concluded that the experimental treatment was effective in improving performance on the immediate posttests. It was observed that some students protect their core belief [see Lakatos, I. (1970). Falsification and the methodology of scientific research programmes. In I. Lakatos & A. Musgrave (Eds.), Criticism and the growth of knowledge (pp. 91–196). Cambridge: Cambridge University Press] in stoichiometry (establishing equivalent relations between different elements or compounds) by ignoring the conflicting data, just as conflicting (anomalous) data do not necessarily convince a scientist to abandon a particular theory.     

How accurate are cited references in Iranian peer‐reviewed journals?

The references cited in scientific articles are as important as any other part of the paper, because of their usefulness to the scientific community and to abstracting and indexing services and citation databases. I studied inaccuracies in references and in‐text citations in sample of 97 of the 519 peer‐reviewed journals accredited by the Iranian National Commission for Journal Accreditation Policy (Ministry of Research, Science and Technology). The target journals published 2,980 articles with 74,577 cited references and 108,151 in‐text citations. The results showed 36.6% as the average percentage error rate (range 5.6% to 61.3%). The mean number of errors in cited reference and in‐text citations was 2.7 per article, and the mean number of errors per journal was 690. For the entire sample of articles, 4,369 in‐text citations did not match any source in the list of references (4%), and 8,683 cited references did not match any in‐text citation (11.6%). The stakeholders in scholarly communication, especially authors, pay insufficient attention to the accuracy of bibliographic references. Peer‐reviewed journals should encourage the use of standardized journal policies and quality‐control measures regarding peer review, data quality and accuracy.     

Book reviewed

Asia Pacific Education Review -     

School-university partnerships: a new recipe for creating professional knowledge in school

This paper first reviews the literature on school-university partnerships to evaluate and describe challenges and paradigms of Japanese approaches to school-university partnerships in theory and practice. Secondly, it clarifies the role of three-year school-university partnership between the Nagoya University and the Tokai City Board of Education in the central Japan for creating an effective environment in schools for teachers to learn from each other and for developing more learning-centered education that focuses on the real needs of students. From this study it can be claimed that more effective relationships between Japanese school teachers and university researchers can be established through developing collaborative a school-based research framework especially through the process of jugyou kenkyuu (lesson study).