New insights on the utilization of ultrasonicated mustard seed cake: chemical composition and antagonistic potential for root-knot nematode,Meloidogyne javanica

This study focused, for the first time, on the effect of ultrasonic features on the extraction efficiency of secondary metabolites in mustard seed cake(MSC). The nematostatic potential of sonicated seed cake was examined against the second-stage juveniles(J2 s) of root-knot nematode, Meloidogyne javanica. The results show that a 35 ppm(parts per million) concentration of a sonicated extract(SE) sample of MSC caused 65% J2 s mortality at 18 h exposure period in vitro. It also significantly suppressed the root-knot index(RKI=0.94) in tomato roots. The lethal concentration values for SE were 51.76, 29.79, and 13.34 ppm,respectively, at 6, 12, and 18 h of the exposure period, and the lethal concentration values for the non-sonicated extract(NSE)sample were 116.95, 76.38, and 55.59 ppm, respectively, at similar exposure time. Sinapine and gluconapin were identified as the major compounds in ultrasonic-assisted MSC. Because of the high extraction efficiency of metabolites in the SE, all treatments of SE were shown to be antagonistic to J2 s. Thus, this study of ultrasonication activity-based profiling of MSC may help generate target-based compounds at a scale relevant to the control of disease caused by nematodes in economic crops.     

Facilitating Conceptual Change in Students’ Understanding of Boiling Concept

The objective of this study was to construct a teaching strategy for facilitating students’ conceptual understanding of the boiling concept. The study is based on 52 freshman students in the primary science education department. Students’ ideas were elicited by a test consisting of nine questions. Conceptual change strategy was designed based on students’ alternative conceptions. Conceptual change in students’ understanding of boiling was evaluated by administering a pre-, post- and delayed post-test. The test scores were analysed both by qualitative and quantitative methods. Statistical analysis using one-way ANOVA of student test scores pointed to statistically significant differences in the tests and total scores (p < 0.05). Quantitative analysis of students’ responses on each test revealed different schema about changing their knowledge system. Both qualitative and quantitative analyses suggest that the teaching activities facilitated students’ conceptual understanding. No statistically significant differences were found between post-test and delayed post-test scores, suggesting that the teaching strategy enabled students to retain their new conceptions in the long-term memory.     

Exploring the utility of action research to investigate second‐language classrooms as complex systems

Action research is geared to changes for the better and has the potential to assist teachers to extend their teaching skills and develop a deeper understanding of themselves, their classroom and their learners. However, in the area of applied linguistics, the viability of action research has been seriously questioned. In this article, we argue that adopting a complexity‐theory perspective, which requires teachers to be dynamic and complex in their approach, helps in identifying action research as a suitable research tradition for investigating second‐language classrooms and in turn using it widely to invigorate the field of applied linguistics. Our argumentation is supported by the fundamental links between action research and complexity theory as an emerging paradigm in education. Although the case made in this article concerns second‐language classrooms, the conclusions reached may well apply to any classroom that shares some commonalities with second‐language classrooms.     

Enhancing thinking skills: Domain specific/ domain general strategies

The main objective of this article is to provide a framework, based on a critical appraisal of the philosophy of science, that could help science educators to choose between domain-specific and domain-general strategies for enhancing the thinking skills of their students. Recent literature has emphasized that one of the most pervasive features of scientific practice is that of gathering evidence by making observations and conducting experiments. Research suggests that children do manifest, in a rudimentary form, the scientific thinking skills of raising causal questions, generating hypotheses and conducting experiments in order to test hypotheses, and that these skills increase progressively with age. It is concluded that we should not in the science classroom, emphasize only domain-specific knowledge. Absence of a single scientific method provides the occasion to shift from one method to another, thus facilitating competing frameworks of understanding. Evidence is provided to show that emphasizing domain specific (content) over domain general knowledge is consistent with a Kuhnian perspective of normal science. On the other hand, adopting the Lakatosian perspective would enable the students to understand that scientific progress goes through a process of conflicting frameworks, based on processes that require elaboration of rival hypotheses and their evaluation. It is concluded that the content-process dichotomy is misleading as the two approaches to teaching science would rather complement each other.     

The Oil Drop Experiment: An Illustration of Scientific Research Methodology and its Implications for Physics Textbooks

The objectives of this study are:(1) evaluation of the methodology used in recent search for particles with fractional electrical charge (quarks) and its implications for understanding the scientific research methodology of Millikan; (2) evaluation of 43 general physics textbooks and 11 laboratory manuals, with respect to the oil drop experiment, based on seven history and philosophy of science criteria. Results obtained show that all the textbooks and manuals ignored the Millikan–Ehrenhaft controversy and in general lacked a history and philosophy of science perspective. In spite of the anomalous data, Millikan adhered to the guiding assumptions of his research program. Ehrenhaft's work strictly followed the logic of experimental observations. Although, Ehrenhaft's work approximated the traditional scientific method, the scientific community supported Millikan. General physics textbooks and laboratory manuals present the oil drop experiment as an example of the scientific method in which experimental data implicitly serves as an arbiter in the defense of Millikan. It is suggested that textbooks and manuals by including the Millikan–Ehrenhaft controversy and the methodology used in the search for quarks could enrich students' understanding of scientific research methodology, viz., experimental data do not always dictate the choice of a theory.     

Role of the epistemic subject in Piaget's genetic epistemology and its importance for science education

According to Piaget, a fundamental epistemological distinction must be made between the psychological and the epistemic subject. The epistemic subject is studied by the genetic epistemologist who charts development through a “common universal rationality, which develops,” whereas the psychological subject is studied by the developmental/cognitive psychologist by focusing on accidental contingencies surrounding particular people and their individual differences. The epistemic subject as compared to the psychological subject is an idealized abstraction, viz., that set of underlying epistemic structures common to everyone at the same level of development. The objective of this study is to investigate the degree to which investigators in science education conceptualize the difference between the epistemic and the psychological subjects. It is argued that just as the ideal gas law (based on the theoretical formulation of Maxwell and Boltzmann) provides a “general model” to which the real gases approximate under different experimental conditions, so we can consider (by abduction) the epistemic subject to be an “ideal knower” to which the real (psychological) subjects approximate to varying degrees. The difference between the epistemic and the psychological subjects, however, cannot be used as an “epistemological shield” in defense of Piagetian theory. Any test of the Piagetian theory must involve psychological or real subjects. Empirical testability, however, need not be equated to being scientific. An analogy is drawn between Galileo's idealization, which led to the discovery of the law of free-fall, and Piaget's epistemic subject. Research conducted in science education shows that at least for some critics the wide variations in the age at which individuals acquire the different Piagetian stages is crucial for rejecting the theory. It is argued that the real issue is not the “proportion of heterogeneity” but the understanding that Piaget, by neglecting individual differences, attempts to build a general model applicable across types of situations/subjects. The distinction between the epistemic and the psychological subjects is important not for defending Piaget's theory (which has serious theoretical flaws) but to understand epistemic transitions, for example, the one between Piaget's epistemic subject and Pascual-Leone's metasubject. It is concluded that failure to understand the distinction between the epistemic and the psychological subjects would lead to misconstruing the significance of our research findings and, what is more serious, to a lack of a historical perspective.     

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