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Physical and virtual labs have unique capabilities that can influence how students learn from them. The purpose of this study was to examine the effect of physical and virtual manipulatives on students’ learning of heat and temperature and to examine the influence of various combinations of physical and virtual manipulatives. A total of 205 participants were divided into four groups: only physical manipulatives, only virtual manipulatives, physical-virtual manipulatives, and virtual-physical manipulatives. Students’ knowledge acquisition was tested using Pre-test–Post-test design. The results showed that physical and virtual manipulatives are as effective in facilitating students’ learning of state changes, but virtual manipulatives are more beneficial to students’ learning of thermal expansion and contraction than physical manipulatives are. Physical-virtual manipulatives are more effective than virtual-physical manipulatives or physical manipulatives alone are to promote students’ learning of heat and temperature, but this effect is similar to that of virtual manipulatives alone. The results suggest that virtual laboratories can effectively model abstract concepts. The better effect of the physical-virtual operation sequence on learning does not depend on whether the two types of experiments are combined or on the sequence of operations but on the type of experiment when its advantages actually contribute to learning. Keywords: experimental design, heat and temperature, physical manipulative, virtual manipulative

tRNAHis guanylyltransferase (Thg1) catalyzes the 3′-5′ incorporation of guanosine into position -1 (G-1) of tRNAHis. G-1 is unique to tRNAHis and is crucial for recognition by histidyl-tRNA synthetase (HisRS). Yeast Thg1 requires ATP for G-1 addition to tRNAHis opposite A73, whereas archaeal Thg1 requires either ATP or GTP for G-1 addition to tRNAHis opposite C73. Paradoxically, human Thg1 (HsThg1) can add G-1 to tRNAsHis with A73 (cytoplasmic) and C73 (mitochondrial). As N73 is immediately followed by a CCA end (positions 74–76), how HsThg1 prevents successive 3′-5′ incorporation of G-1/G-2/G-3 into mitochondrial tRNAHis (tRNAmHis) through a template-dependent mechanism remains a puzzle. We showed herein that mature native human tRNAmHis indeed contains only G-1. ATP was absolutely required for G-1 addition to tRNAmHis by HsThg1. Although HsThg1 could incorporate more than one GTP into tRNAmHisin vitro, a single-GTP incorporation prevailed when the relative GTP level was low. Surprisingly, HsThg1 possessed a tRNA-inducible GTPase activity, which could be inhibited by ATP. Similar activity was found in other high-eukaryotic dual-functional Thg1 enzymes, but not in yeast Thg1. This study suggests that HsThg1 may downregulate the level of GTP through its GTPase activity to prevent multiple-GTP incorporation into tRNAmHis.

The purpose of this study was to investigate the relative effectiveness of experimenting with physical manipulatives alone, virtual manipulatives alone, and virtual preceding physical manipulatives (combination environment) on third-grade students’ science achievement and conceptual understanding in the domain of state changes of water, focusing on the concepts of evaporation and condensation. A pretest-posttest design was used that involved 208 third-grade students assigned to the three learning conditions. A science achievement test and a two-tier conceptual test were administered to students before and after a teaching intervention. The results revealed that using virtual preceding physical manipulatives and virtual manipulatives alone enhanced students’ knowledge gains about evaporation and condensation greater than the use of physical laboratory activities alone. It was also found that the combination environment promoted students’ knowledge gains about these concepts equally well as the use of virtual laboratory activities alone. On the other hand, the results showed that using virtual preceding physical manipulatives promoted students’ conceptual understanding most efficiently compared to the use of either physical or virtual manipulatives alone; in contrast, experimenting with physical manipulatives alone was least influential for students’ conceptual understanding compared to the other manipulatives.

Diuron is an herbicide, which is used to control a wide variety of annual and perennial broadleaf, grassy weeds, and mosses. However, the toxicity of diuron in HepG2 cells and zebrafish embryos was unclear. In this study, HpeG2 cells and zebrafish embryos were exposed to different concentrations of diuron for 24 h and 48 h, respectively. Results reveal the diuron caused cytotoxicity and the generation of reactive oxygen species (ROS) in the treated HepG2 cells. The effects of diuron on the expression of catalase and superoxide dismutase (SOD1 and SOD2), an antioxidant enzyme, were investigated. Results showed that only SOD1 was significantly induced after treated diuron 48 h, but the expression of catalase and SOD2 was unaffected. Additionally, the cytotoxicity of diuron was not attenuated in cells pretreated with of N-acetyl-cysteine (NAC), a well-known antioxidant, indicating that oxidative stress could not contribute to cellular death in the treated HepG2 cells. In zebrafish embryos, results from proteomic analysis show that 332 differentially upregulated proteins and 199 down-regulated proteins were detected in the treated embryos (P 0.05). In addition to the up-regulated antioxidant proteins (prdx3, cat, prdx4, txnrd1, prdx1, sod1, prdx2, and sod2), some decreased proteins were related to cytoskeleton formation, tight junction, and gap junction, which could be related to the malformation of the treated zebrafish embryos. In summary, diuron caused cytotoxicity in HepG2 cells, and the mechanisms of toxicity in zebrafish were addressed using the proteomic analysis.

Background:This study analyzed geometry problems in four middle-grade mathematics textbook series from Taiwan, Singapore, Finland, and the United States, while exploring the expectations for students’ learning experiences with these problems.Material and methods:An analytical framework developed for mathematics textbook problem analysis had three dimensions: representation forms, contextual features, and response types.Results:The results showed that Taiwanese and Singaporean textbooks contained more problems in combined form, whereas Finnish and the American textbooks contained more problems in verbal and visual forms. The problem distribution across various representation forms was more balanced in the Finnish and Singaporean textbooks than in the Taiwanese and American textbooks. Most problems were non-application and close-ended problems compared to other application and open-ended problems. The Taiwanese textbooks contained the lowest proportion of real-world problems, whereas the American textbooks contained the highest proportion of open-ended problems.Conclusions:Implications of this study’s findings for textbook developers and future research directions are discussed.

The purposes of this study were to explore the effects of thinking styles on science achievement and attitudes toward science class among Taiwanese elementary school students and to explore the differences between male and female students in their modes of thinking. Participants included 756 sixth-grade students from 28 classes in four elementary schools in Taiwan. Data were collected from three data sources: (a) Style of Learning and Thinking to identify students’ thinking style, (b) Science Achievement Test to assess students’ science achievement, and (c) Asian Student Attitudes Toward Science Class Survey to measure students’ attitudes toward science class. Findings revealed that across both boys and girls, there were significant differences between the three modes of thinking with regard to attitudes toward science class but no significant difference between the three modes of thinking with regard to science achievement. Even though students of both genders tended to be more holistic in their thinking, students with an analytic thinking style and an integrative thinking style showed more positive attitudes toward science class than students with a holistic thinking style. Taiwanese male students tended to be more holistic thinking than their female counterparts, whereas Taiwanese female students tended to be more analytic thinking in contrast to male students.

This paper is a report of a quasi-experimental study on the impact of a systemic 5-year, K-6 professional development (PD) project on the ‘high stakes’ achievement test scores of different student groups in rural mid-west school districts in the USA. The PD programme utilized regional summer workshops, district-based leadership teams and distance delivery technologies to help teachers learn science concepts and inquiry teaching strategies associated with a selection of popular science inquiry kits and how to adapt inquiry science lessons in the kits to teach and reinforce skills in the language arts—i.e. to teach more than science when doing inquiry science. Analyses of the school district-level pre-post high-stakes achievement scores of 33 school districts participating in the adaptation of inquiry PD and a comparative group of 23 school districts revealed that both the Grade 3 and Grade 6 student-cohorts in the school districts utilizing adapted science inquiry lessons significantly outscored their stud...

This paper is a report of the impact of an externally funded, multiyear systemic reform project on students' science achievement on a modified version of the Third International Mathematics and Science Study (TIMSS) test in 33 small, rural school districts in two Midwest states. The systemic reform effort utilized a cascading leadership strategy of professional development delivered at summer workshops and through distance technologies and local leadership groups that focused on helping teachers work in communities of practice to adapt science inquiry lessons to teach and reinforce strategies and skills in language arts in the lessons. Science achievement scores of Grade 3 and Grade 6 student cohorts on the two forms of the TIMSS administered at the beginning, middle, and end of the professional development effort revealed a V-shaped pattern of scores, suggesting that teachers struggled with the newly adapted science inquiries at first but then became more effective in their use. The impact of the adaptation strategy on the students' achievement, questions about the time needed for new instructional strategies to be embraced by teachers, and the wisdom of using “low stakes” achievement tests in studies are discussed.

The purposes of this study were to compare the differences in the use of geometry in elementary school mathematics textbooks among Finland, Mainland China, Singapore, Taiwan, and the USA and to investigate the relationships between the design of the textbooks and students' performance on large-scale tests such as TIMSS-4 geometry, TIMSS-8 geometry, and PISA space and shape. The content analysis method was used to collect data, and then chi-square tests and correlation analyses were used to analyze data. The results showed that there were significant differences in representation form, problem type, and question format among these mathematics textbooks from the five countries. Moreover, the strength of the positive relationships between visual form (combined form) and students' performance on TIMSS-4 geometry, TIMSS-8 geometry, and PISA space and shape decreases as students advance to higher grades, whereas increasing strength of correlations as students get older is found between contextual problems and students' performance on the three large-scale tests.

Pteris multifida Poiret (Pteridaceae), also known as Fong-Wei-Cao, is the most commonly used material in herb beverages in Taiwan and also used as one of the vegetable resources in Main China. The aqueous extract of P. multifida Poiret (AEPM) was prepared and its antioxidant and free radical-scavenging activities were studied. AEPM showed high antioxidant activities by conjugated diene method. At 20 mg/mL, AEPM exhibited high scavenging effects on α-diphenyl-β-picrylhydrazyl, hydroxyl, ferrous radical (82.5, 80.1 and 85.4, respectively) and reducing power (Abs, 700 nm = 1.03). AEPM has various antioxidant activities that may be due to the different naturally occurring antioxidant components. PRACTICAL APPLICATIONS Consumers need high-quality herb-beverage products and to understand their potential functions. Our results indicated that the qualities of aqueous extract of P. multifida Poiret possess antioxidant and free radical-scavenging activities and this evidence could be regard as the important scientific basis.

This paper is a report of a study that examines the relationship between teacher participation in a multi-year, K–6 professional development effort and the “high stakes” science test scores of different student groups in 33 rural mid-west school districts in the USA. The professional development program involved 1,269 elementary school teachers and utilized regional summer workshops and distance delivery technologies to help the teachers learn science concepts, inquiry teaching strategies, and how to adapt science inquiry lessons to teach and reinforce skills in the language arts. Regression analyses revealed a significant positive relationship between the professional development hours experienced by teachers and student gains on high stakes test scores. But the analyses also suggest that primary grade teachers need less professional development than upper grade teachers on instructional strategies where the focus is on the integration of language arts and science inquiry. The implications for funding and implementing professional development projects are discussed.

The main purpose of this study is to develop a valid and reliable instrument for measuring the attitudes toward science class of fourth‐ and fifth‐grade students in an Asian school culture. Specifically, the development focused on three science attitude constructs—science enjoyment, science confidence, and importance of science as related to science class experiences. A total of 265 elementary school students in Taiwan responded to the instrument developed. Data analysis indicated that the instrument exhibited satisfactory validity and reliability with the Taiwan population used. The Cronbach’s alpha coefficient was 0.93 for the entire instrument indicating a satisfactory level of internal consistency. However, both principal component analysis and parallel analysis showed that the three attitude scales were not unique and should be combined and used as a general “attitudes toward science class” scale. The analysis also showed that there were no gender or grade‐level differences in students’ overall attit...

Two oligomeric types of glycyl-tRNA synthetase (GlyRS) are found in nature: a α2 type and a α2β2 type. The former has been identified in all three kingdoms of life and often pairs with tRNAGly that carries an A73 discriminator base, while the latter is found only in bacteria and chloroplasts and is almost always coupled with tRNAGly that contains U73. In the yeast Saccharomyces cerevisiae, a single GlyRS gene, GRS1, provides both the cytoplasmic and mitochondrial functions, and tRNAGly isoacceptors in both compartments possess A73. We showed herein that Homo sapiens and Arabidopsis thaliana cytoplasmic GlyRSs (both α2-type enzymes) can rescue both the cytoplasmic and mitochondrial defects of a yeast grs1 - strain, while Escherichia coli GlyRS (a α2β2-type enzyme) and A. thaliana organellar GlyRS (a (αβ)2-type enzyme) failed to rescue either defect of the yeast mull allele. However, a head-to-tail αβ fusion of E. coli GlyRS effectively supported the mitochondrial function. Our study suggests that a α2-type eukaryotic GlyRS may be functionally substituted with a α2β2-type bacterial cognate enzyme despite their remote evolutionary relationships.