Search

A scaffolding-based mind tool was designed to allow teachers to easily create lesson plans for in-class gamified activities and to embed various scaffoldings in the lesson plan design. The purpose of this study was to investigate the learning outcomes of a scaffolding-based mind tool integrated with gamified learning activities applied to a science course. The study was conducted to investigate students' learning outcomes, flow, and qualitative feedback on the scaffolding-based mind tool. A total of 134 high school students participated in the experiment. The results showed that the gamified activity with the scaffolding-based mindtool significantly improved students' learning effectiveness, but the learning effectiveness did not differ significantly from that of the students in the lecture-based instruction. In addition, the study found that the learners' flow was high, the students were engaged in the activity. The qualitative feedback analysis also revealed high positive evaluations of the usefulness of the gamified activity, mind tool, and scaffolds. In addition, students with low prior knowledge or low learning effectiveness had significantly higher active engagement in flow than those with high prior knowledge/learning effectiveness.

This article reports the design of a scientific board game, named "Element Enterprise Tycoon" (EET), which creates a scenario combining chemical elements, techniques, and products in daily life. The game cards are designed to motivate students not only to retrieve information about chemical elements, but also to be proficient in chemistry. Moreover, the game creates opportunities for group interactions and competitions to engage students in learning chemical elements as they do in regular science curricula. The EET has been field-tested with a group of middle school students to evaluate its applicability. Empirical data show that students improve their understanding of chemistry concepts with a median level of effect size. In particular, students achieve better performance in terms of chemistry-related technique concepts. The follow-up interviews reflect students' positive feedback and attitudes toward science learning through board game playing and their willingness to continue to play the game. It is suggested that learning through science games can indeed help students learn new chemical knowledge.

This work describes the evaluation of the Attitude toward the Subject of Chemistry Inventory (ASCI), as well as two modifications (one for measuring attitude toward math and one for measuring attitude toward biology), for college students at a Hispanic Serving Institution. Instrument reliability was tested via multiple administrations of the instruments, and confirmatory factor analysis supported a two-factor structure similar to an existing model of a revised version of the ASCI for all three instruments. The similar factor structure of the three instruments, coupled with interviews with students, provide validity evidence for the instruments and support an interpretation that one of the subscales aligns with a cognitive aspect of attitude while the other subscale aligns with an affective aspect. The results of these instruments indicate that students have a more positive attitude toward biology than either chemistry or math, and more positive affective attitude than cognitive attitude for all three subjects, although student attitudes show little change with respect to biology, chemistry, or math during a typical semester. However, major perturbations, such as switching to remote instruction midsemester, can lead to small but significant increases and decreases in attitude.

As a representative catabolic reaction that widely exists in nature, anaerobic digestion (AD) exhibits great value regarding the global carbon cycle, renewable energy development, and environmental protection. Such an important biochemical reaction was ignored before and should be introduced into the teaching and textbooks of undergraduate biochemistry courses. However, students may face obstructions when learning AD theories since the metabolic pathways in AD are very complex. To solve these problems, an instructive metabolic minimap of the AD reaction was designed, including its reaction stages, reaction pathways, substrates, and enzymes. Furthermore, the interrelationships between aerobic catabolism (AEC) and anaerobic catabolism (ANC) were also summarized by combining the catabolic pathways of typical biological macromolecules. In this paper, AD theories were first replenished into undergraduate biochemistry courses by metabolic minimap, which not only provided valuable supports for the practical teaching of AD in undergraduate biochemistry courses, but also acted as an important reference for students in biology-related majors and biochemistry teachers.

As simple and ubiquitous redox-active organic molecules, quinones participate in diverse electron transfer processes in chemistry and biological systems for energy transformation and signal transduction. We introduce here a practical exercise to study the redox potentials of benzoquinone and its two derivatives by combining the electrochemistry method with quantum chemistry computation. The practical reduction potentials of three quinones were measured by cyclic voltammetry experiment. Quantum chemistry computation, on the other hand, provided theoretical Gibbs free energy change and reduction potentials of the three quinones, which were found to be in line with the experimental results. Detailed thermodynamic energy analysis based on the computation results revealed that the reduction Gibbs free energy changes of the three quinones were mainly contributed from the electronic energies change of the molecules, while thermal energy and entropy played a relatively minor role. The energy levels of the lowest unoccupied molecular orbital (LUMO) of the three quinones, which were modulated by substituent groups and conjugation structures, were further identified as the main origin of the reduction potential. This experiment provides practical and theoretical training on the fundamental ideas involved in major courses like thermodynamics, quantum chemistry, electrochemistry, and organic chemistry, and promotes students to find the tie between macroscopic redox properties of chemicals and their microscopic molecular structures, a key topic in chemistry education.

A comprehensive undergraduate experiment about extraction, separation, and identification of essential oils (EOs) from a natural plant is described. "Acori tatarinowii" Rhizoma (ATR) was used as the raw plant material. Two devices (Soxhlet and Clevenger) with different extraction principles were employed for EO extraction from ATR, separately. The chemical compounds of the extracted EOs were separated and identified by gas chromatography-mass spectrometry (GC-MS). The differences in the chemical components obtained by the two extraction devices were compared. The experiment can give students a deep insight into the difference between the extraction methods. Additionally, the experiment can enable students to learn how to use GC-MS to identify the chemical structures of the extracted complex samples. The grouped students who performed this experiment gained a deep understanding of extraction and detection techniques, as well as the benefits of teamwork.

According to the definition, surface tension could be affected not only by intermolecular interaction but also by molecular area. However, in chemistry textbooks, surface tension is mainly explained only in terms of intermolecular interaction. Although the existing surface tension concept in the textbooks can lead to a variety of counterexamples, research on undergraduates' responses to surface tension anomalies is rare. In this study, we had 16 undergraduates experience an anomalous surface tension experiment and analyzed how they responded to the anomalous data and whether their explanations had met conditions for accommodation. As a result, among the 16 participants, only one student (rejection response) retained her existing conception (i.e., surface tension is proportional only to the intermolecular interaction), and the rest of the students tried to explain the anomaly in their own ways (theory change, peripheral theory change, and abeyance responses). In particular, only the six students who considered both intermolecular interaction and molecular area properly showed a theory change response that matched conditions for accommodation (dissatisfaction, intelligibility, and plausibility). The results of the study imply that the surface tension concept considering both intermolecular interaction and molecular area might be an alternative to the existing concept in chemistry education.

We present a critical discussion of how chemistry textbooks treat the electrolysis of water and aqueous salt solutions, based on a survey of general chemistry textbooks in English and Korean at secondary and tertiary levels, also informed by the historical background of 19th-century debates. English-language textbooks present various and contradictory accounts of the electrolysis of water; a key point of disagreement is whether hydrogen and oxygen gases originate from pre-existing H[superscript +] and OH[superscript -] ions, or from the direct reduction and oxidation of H[subscript 2]O molecules. School textbooks in South Korea all present the same account, with no indication of alternative views. A vast majority of all texts ignore the possibility that H[subscript 2] and O[subscript 2] may result from secondary reactions, which was a standard view in the late 19th century following the works of Daniell and Miller. Concerning the electrolysis of aqueous salt solutions, all texts give oversimplified views of competing reactions based on standard reduction/oxidation potentials. It is understandable that textbooks try to present sufficiently simple pictures that students at each level can handle; however, this should not be done in a way that shuts down questions. We recommend that students should be made aware that textbook accounts are only models, and encouraged to extend their learning beyond the models. The plausibility of our recommendations is shown in a pilot study we conducted with secondary school students in South Korea.

This comprehensive experiment is specially designed for the third-year and above students who are majoring in chemistry, applied chemistry, and chemical engineering. Students conduct experiments in groups, which are required to synthesize the CeO[subscript 2]-NiTiO[subscript 3]/attapulgite (ATTP) composite catalyst by the sol-gel method; the resulting catalysts are further used in the research of low-temperature selective catalytic reduction (SCR) denitration to investigate the conversion rate of NO[subscript x], sulfur resistance, N[subscript 2] selectivity, and stability of the catalyst. Through this comprehensive experiment based on research, students can have a full understanding of the characterization of the catalyst and master a basic analytical ability. Meanwhile, students are guided to realize the importance of environmental protection and understand how to use chemistry to carry out environmental restoration. Furthermore, in this comprehensive experiment, students' experimental skill and the team spirit of cooperation are cultivated, which lay a solid foundation for the later graduation thesis.

In this study, we reviewed 76 journal articles on employing drawing assessment as a research tool in science education. Findings from the systematic review suggest four justifications for using drawing as a type of research tool, including assessment via drawing as (a) an alternative method considering young participants' verbal or writing abilities, and affective or economic reasons, (b) a unique method that can reveal aspects not easily measured by other methods, (c) a major method that reflects characteristics of science subjects, and (d) a formative assessment to diagnose students' ideas to benefit their learning. Furthermore, five research trends of studies using drawing as assessment tools are identified, including: (a) students' conceptions of scientists from the Draw-a-Scientist-Test (DAST) and evolving studies, (b) students' understanding or mental models of science concepts, (c) participants' conceptions of science learning or teaching, (d) students' inquiry abilities and modelling skills via drawing, and (e) technology to support drawing. For each trend, we synthesised and commented on the current findings. A framework conceptualising phases and issues when designing research and instruments employing drawing assessments is proposed. The review provides insights into the design and future direction of research employing drawing assessments in science education.

In recent years, the curricula reforms at the levels of preschool and primary school in Sweden have caused new demands on the teachers. In particular, numerous teachers lack the educational training in science subjects. Therefore, this study aims to investigate teachers' self-efficacy and needs in relation to science teaching. A total of 71 teachers, divided into three groups of preschool, 1-3 grades and 4-6 grades, were invited to join this pilot study. From the EU FP7 project, PROFILES, a Likert scale questionnaire (with scores from 1 to 3 to represent "strongly disagree," "agree" to "strongly agree," and "I don't know" was scored 0) was used and revised for the data collection in this pilot study. The results showed that the participating teachers had relatively high self-efficacy and no significant differences were found among the three groups of teachers. However, even though the teachers had high self-efficacy, the needs of further education were expressed by the teachers to a large extent. In particular, the group of preschool teachers addressed the need for more content knowledge (CK) in physics and chemistry (>41%). In terms of the groups of 1-3 and 4-6 grades teachers, the needs relating to scientific literacy were revealed, with a focus on engaging students in socio-scientific problems (52%, 56%) and assessment (44%, 61%). The implication of this study is discussed in the hope to contribute to teachers' professional development for both pre- and in-service teachers in science education.

The scale-invariant way to analyze two-dimensional experimental and theoretical data with statistical errors in both the independent and dependent variables is revisited by using what we call the triangular linear regression method. This is compared to the standard least-squares fit approach by applying it to typical simple sets of example data from the actual chemical literature. A new add-in for Microsoft Excel, LinEstXY, and ready-to-use formulas for the scale-invariant method are provided.

Three internally developed mobile apps, "3D Sym Op", "SM2 Chem" and "ARMolVis," available for free on both the Apple App Store and Google Play Store were evaluated in seven studies. Each study was a systematic process of Pre-Test, In-lecture App Demo, App Assisted Interactive Tutorials (AAITs) and/or Independent App Usage (IAU), followed by a Survey and Post-Test. Overall, the mobile apps were effective evident by the higher Post-Test vs. Pre-Test % increase for those who used the app more frequently compared to those who used the app rarely. Apps were most effective when used in AAITs with the Blended Learning approach. This approach requires the physical presence of both teacher and student, but with some element of student free play such as using the app to complete worksheets in pairs or groups.

Background: Textbooks are integral tools for teachers' lessons. Several researchers observed that school teachers rely heavily on textbooks as informational sources when planning lessons. Moreover, textbooks are an important resource for developing students' knowledge as they contain various representations that influence students' learning. However, several studies report that students have difficulties understanding models in general, and chemical bonding models in particular, and that students' difficulties understanding chemical bonding are partly due to the way it is taught by teachers and presented in textbooks. Purpose: This article aims to delineate the influence of textbooks on teachers' selection and use of representations when teaching chemical bonding models and to show how this might cause students' difficulties understanding. Sample: Ten chemistry teachers from seven upper secondary schools located in Central Sweden volunteered to participate in this study. Design and methods: Data from multiple sources were collected and analysed, including interviews with the 10 upper secondary school teachers, the teachers' lesson plans, and the contents of the textbooks used by the teachers. Results: The results revealed strong coherence between how chemical bonding models are presented in textbooks and by teachers, and thus depict that textbooks influence teachers' selection and use of representations for their lessons. As discussed in the literature review, several of the selected representations were associated with alternative conceptions of, and difficulties understanding, chemical bonding among students. Conclusions: The study highlights the need for filling the gap between research and teaching practices, focusing particularly on how representations of chemical bonding can lead to students' difficulties understanding. The gap may be filled by developing teachers' pedagogical content knowledge regarding chemical bonding and scientific models in general.

Researchers have shown a growing interest in science teachers' professional knowledge in recent decades. The article focuses on how chemistry teachers impart chemical bonding, one of the most important topics covered in upper secondary school chemistry courses. Chemical bonding is primarily taught using models, which are key for understanding science. However, many studies have determined that the use of models in science education can contribute to students' difficulties understanding the topic, and that students generally find chemical bonding a challenging topic. The aim of this study is to investigate teachers' knowledge of teaching chemical bonding. The study focuses on three essential components of pedagogical content knowledge (PCK): (1) the students' understanding, (2) representations, and (3) instructional strategies. We analyzed lesson plans about chemical bonding generated by 10 chemistry teachers with whom we also conducted semi-structured interviews about their teaching. Our results revealed that the teachers were generally unaware of how the representations of models they used affected student comprehension. The teachers had trouble specifying students' difficulties in understanding. Moreover, most of the instructional strategies described were generic and insufficient for promoting student understanding. Additionally, the teachers' rationale for choosing a specific representation or activity was seldom directed at addressing students' understanding. Our results indicate that both PCK components require improvement, and suggest that the two components should be connected. Implications for the professional development of pre-service and in-service teachers are discussed.

This study explores the feasibility of using Cu/AZO thin films as low-emissivity materials with antibacterial properties, fabricated using the linear sputtering method. The linear sputtering technique deposits thin films onto continuous substrates, offering high throughput, uniform coatings, and precise control over film properties. In this research, Cu/AZO thin films underwent either vacuum annealing or hydrogen plasma annealing treatments. The Cu layer imparts antibacterial properties, while the AZO layer primarily provides thermal insulation. Experimental results show that annealing treatments enhance both photoelectric performance and antibacterial capability. Annealed Cu/AZO films exhibit lower resistivity and emissivity. Among the samples, those subjected to vacuum annealing at 400 °C are most suitable for low-emissivity applications, with an average visible light transmittance of 60%, an emissivity of 0.16, and an antibacterial activity value of 8.8. The Cu/AZO films proposed in this study effectively combine antibacterial and thermal insulation properties, making them relevant for the field of green materials.

Abstract Periodontal disease presents a significant challenge in oral health due to its chronic inflammatory nature and subsequent degradation of tooth-supporting structures. Natural compounds have attracted attention for their potential therapeutic effects in alleviating symptoms of periodontitis (PD). In this study, we investigated the impact of Ganoderma lucidum spore oil (GLSO), a lipid component extracted from broken-walled GLS using the supercritical CO2 extraction method, on PD pathogenesis in vitro and in vivo. Treatment of human gingival fibroblasts with GLSO resulted in a significant reduction in the expression of inflammatory factors, including matrix metalloproteinase (MMP)-1 and interleukin (IL)-8, upregulated by lipopolysaccharide or IL-1β. Molecular mechanism studies revealed that the observed decrease in inflammatory factor expression may be attributed to the inhibition of phosphorylated c-Jun N-terminal kinase activity by GLSO. Furthermore, intraperitoneal injection of GLSO in a ligature-induced PD mouse model led to a notable reduction in periodontal inflammation and alveolar bone loss, accompanied by decreased levels of MMP-1 and IL-8. These in vivo results support the potential therapeutic efficacy of GLSO in alleviating PD symptoms. Overall, our study provides novel insights into the beneficial effects of GLSO in PD management. Further research is warranted to elucidate the underlying molecular mechanisms and explore the clinical applicability of GLSO as a promising therapeutic agent for PD treatment.

Abstract Ultraviolet-B (UVB) radiation-induced photoaging of the skin is characterized by amplified expression of matrix metalloproteinase-1 (MMP-1) and reduced collagen fibers, both of which contribute to skin wrinkle formation. Edible natural products can protect against skin photoaging. Here, we investigate the protective effect of Dolichos lablab Linne (DLL) water extract against UVB radiation-prompted skin damage and attempt to uncover its fundamental mechanisms in human keratinocytes (HaCaT) and HR-1 hairless mouse. We found DLL extract rescued the reduction in cell viability associated with UVB exposure without any associated cytotoxic effects. It also protected against skin photoaging by inhibiting mitogen-activating protein kinase (MAPK) signaling, thereby preventing the UVB-associated increase in MMP-1 and -9 expression. DLL extract also increased the expression of both superoxide dismutase 1 (SOD1) and catalase (CAT). We identified chikusetsusaponin IVa, soyasaponin Bb, and sandosaponin A as bioactive components of DLL. Although we have not yet identified the mechanisms by which these compounds reduce the effects of photoaging, we have demonstrated that chikusetsusaponin IVa, soyasaponin Bb, and sandosaponin A reduce MMP-1, MMP-9, p–c-Fos, and p–c-Jun expression, while also avoiding any cytotoxicity. We found oral administration of DLL extract effectively alleviated dorsal epidermal thickening and skin dehydration in HR-1 hairless mouse visible to UVB. DLL extract also prevents UVB-induced activation of the MAPK/AP-1 signaling pathway, thereby reducing the expression of MMPs in dorsal mouse skin. Our results indicate that chikusetsusaponin IVa, soyasaponin Bb, and sandosaponin A are bioavailable components of DLL extract that can reduce UVB-induced skin damage via MMPs by deactivating the MAPK/AP-1 signaling pathway. These findings suggest DLL extract can be used as a skin anti-photoaging agent.

Tropical tropospheric ozone (TTO) is important for the global radiation budget because the longwave radiative effect of tropospheric ozone is higher in the tropics than midlatitudes. In recent decades the TTO burden has increased, partly due to the ongoing shift of ozone precursor emissions from midlatitude regions toward the Equator. In this study, we assess the distribution and trends of TTO using ozone profiles measured by high-quality in situ instruments from the IAGOS (In-Service Aircraft for a Global Observing System) commercial aircraft, the SHADOZ (Southern Hemisphere ADditional OZonesondes) network, and the ATom (Atmospheric Tomographic Mission) aircraft campaign, as well as six satellite records reporting tropical tropospheric column ozone (TTCO): TROPOspheric Monitoring Instrument (TROPOMI), Ozone Monitoring Instrument (OMI), OMI/Microwave Limb Sounder (MLS), Ozone Mapping Profiler Suite (OMPS)/Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2), Cross-track Infrared Sounder (CrIS), and Infrared Atmospheric Sounding Interferometer (IASI)/Global Ozone Monitoring Experiment 2 (GOME2). With greater availability of ozone profiles across the tropics we can now demonstrate that tropical India is among the most polluted regions (e.g., western Africa, tropical South Atlantic, Southeast Asia, Malaysia and Indonesia), with present-day 95th percentile ozone values reaching 80 nmol mol−1 in the lower free troposphere, comparable to midlatitude regions such as northeastern China and Korea. In situ observations show that TTO increased between 1994 and 2019, with the largest mid- and upper-tropospheric increases above India, Southeast Asia, and Malaysia and Indonesia (from 3.4 ± 0.8 to 6.8 ± 1.8 nmol mol−1 decade−1), reaching 11 ± 2.4 and 8 ± 0.8 nmol mol−1 decade−1 close to the surface (India and Malaysia–Indonesia, respectively). The longest continuous satellite records only span 2004–2019 but also show increasing ozone across the tropics when their full sampling is considered, with maximum trends over Southeast Asia of 2.31 ± 1.34 nmol mol−1 decade−1 (OMI) and 1.69 ± 0.89 nmol mol−1 decade−1 (OMI/MLS). In general, the sparsely sampled aircraft and ozonesonde records do not detect the 2004–2019 ozone increase, which could be due to the genuine trends on this timescale being masked by the additional uncertainty resulting from sparse sampling. The fact that the sign of the trends detected with satellite records changes above three IAGOS regions, when their sampling frequency is limited to that of the in situ observations, demonstrates the limitations of sparse in situ sampling strategies. This study exposes the need to maintain and develop high-frequency continuous observations (in situ and remote sensing) above the tropical Pacific Ocean, the Indian Ocean, western Africa, and South Asia in order to estimate accurate and precise ozone trends for these regions. In contrast, Southeast Asia and Malaysia–Indonesia are regions with such strong increases in ozone that the current in situ sampling frequency is adequate to detect the trends on a relatively short 15-year timescale.

Abstract Compartmentalization is a vital aspect of living cells to orchestrate intracellular processes. In a similar vein, constructing dynamic and responsive sub-compartments is key to synthetic cell engineering. In recent years, liquid-liquid phase separation via coacervation has offered an innovative avenue for creating membraneless organelles (MOs) within artificial cells. Here, we present a lab-on-a-chip system to reversibly trigger peptide-based coacervates within cell-mimicking confinements. We use double emulsion droplets (DEs) as our synthetic cell containers while pH-responsive elastin-like polypeptides (ELPs) act as the coacervate system. We first present a high-throughput microfluidic DE production enabling efficient encapsulation of the ELPs. The DEs are then harvested to perform multiple MO formation-dissolution cycles using pH as well as temperature variation. For controlled long-term visualization and modulation of the external environment, we developed an integrated microfluidic device for trapping and environmental stimulation of DEs, with negligible mechanical force, and demonstrated a proof-of-principle osmolyte-based triggering to induce multiple MO formation-dissolution cycles. In conclusion, our work showcases the use of DEs and ELPs in designing membraneless reversible compartmentalization within synthetic cells via physicochemical triggers. Additionally, presented on-chip platform can be applied over a wide range of phase separation and vesicle systems for applications in synthetic cells and beyond.

A series of quinoxalinone-1,2,3-triazole derivatives have been synthesized and tested for antifungal activity against phytopathogenic fungus through mycelial growth inhibition in vitro, spore germination inhibition in vitro and control effect in vivo. The results showed that the pharmacophore quinoxalinone and 1,2,3-triazole displayed promising antifungal activity. The EC50 value against C. gloeosporioides of 6a-1 was 1.17 μg/mL and the compound 6c-1 showed the good bioactivity against C. fragariae Brooks and P. oryzae Cav., displaying EC50 values of 5.56, 4.62 μg/mL, respectively. The inhibitory of spore germination by 6a-1 was performed with EC50 value of 1.91 μg/mL. In addition, the in vivo bioassay indicated that 6a-1 possessed effective control against Pepper Anthrax Disease in protective treatment. For given activity data of target compounds, structure-activity relationship (SAR) study was operated, hoping for optimizing the target structure to find lead compound with higher activity.

A method of ultra-high performance liquid chromatography quadrupole electrostatic field Orbitrap mass spectrometry (UHPLC-Q/Orbitrap MS) was developed for rapid screening illegal additives in diet food. The efficacy of three extraction solvents for methanol, acetonitrile and acetonitrile containing 1% formic acid were evaluated for the extraction of illegal additives from green plums and jellies. Ultimately, acetonitrile is selected to extract illegally additives under ultrasonication. In order to achieve good separation of the additives by UHPLC in diet foods, four mobile phases were compared, including methanol (0.1% formic acid)-water (0.1% formic acid and 5 mmol/L ammonium acetate), acetonitrile (0.1% formic acid)-water (0.1% formic acid and 5 mmol/L ammonium acetate), acetonitrile-water (5 mmol/L ammonium acetate), acetonitrile-water. The effects of mobile phases and acidity levels on the chromatographic behavior of the additives were investigated, and acetonitrile-water containing 5 mmol/L ammonium acetate shows the best performance under appropriate gradient. Then, the MS data were acquired in Full MS/dd-MS2 mode on UHPLC-Q/Orbitrap MS with the matrix-matched external standard method for quantification. Based on the self-constructed database of illegal additives in diet foods, one unknown additive is detected in a diet food containing green plums and jelly. By characterizing the molecular ion peak, secondary fragment ion information, and isotopic information, the unknown compound is identified to be 4-chlorobisacetophenetidin, also an illegal additive, which was verified by computation of density functional theory and analysis of the standard substance. To validate the accuracy and reliability of the method, the limits of detection (LODs), the limits of quantification (LOQs), linear ranges, recoveries, relative standard deviations (RSDs) and matrix effect (ME) for eight compounds were determined. The LODs and LOQs of deacetylbisacodyl and bisacodyl are 0.001 and 0.005 mg/kg, respectively. The LODs and LOQs of other compounds are 0.05 and 0.1 mg/kg, respectively. The correlation coefficient (R2) is higher than 0.999. All of the compounds exhibit varying degrees of MEs from moderate to weak, and the recoveries is in the range of 71.02%-103.01% with the RSDs of 0.87%-13.24%. The approach was applied to diet food containing green plums and jelly. The 4-chlorobisacodyl are detected in 30% of the green plums, suggesting that this method is suitable for the rapid qualitative and quantitative analysis of illegal additives in diet food. It is also demonstrated that the established screening process plays a positive role in identifying potential risk substances. The combination of quantum chemistry computation and mass spectrometry provides a novel strategy for the identification of unknown additives in food.

Abstract Background Mapping the distribution of bioavailable isotope ratios across landscapes serves as an efficient geochemical tool for delineating the origins and migration trajectories of humans and animals. Chungcheongbuk-do Province in central Korea, known for its geological diversity and inland location isolated from coastal influences, provides an ideal area to study the contributions of geological and environmental factors to the isotope landscape (isoscape). This study analyzed the distribution of bioavailable Sr, Nd, and Pb isotopes in the province using plant and soil data obtained in this study and from previous works. Findings Chungcheongbuk-do features diverse geological elements, including Precambrian basement, Paleozoic metasedimentary rocks, and Mesozoic granitoids and volcano-sedimentary sequences. The 87Sr/86Sr ratios of bulk soil samples from 44 sites primarily range from 0.781 to 0.706, with two ratios exceeding 0.9 originating from Precambrian basement and Cretaceous granitoid areas. Fractions of soils treated with 1 M ammonium nitrate and acetic acid exhibit indistinguishable 87Sr/86Sr ratios (R2 = 0.99, except for one point), spanning from 0.804 to 0.707. Plant 87Sr/86Sr ratios demonstrate a robust positive correlation with leachate ratios (for ammonium nitrate data, ( 87 Sr/ 86 Sr) plant = 0.938 × ( 87 Sr/ 86 Sr) leachate + 0.045, R2 = 0.98). The εNd values of bulk soils from Precambrian basement areas (–18 to –30) plot against Sm/Nd ratios around the reference line corresponding to 3 Ga, while other bulk soil samples (εNd = –1 to –21) align with a younger (~ 2 Ga) reference line. Plant εNd values, ranging from –4 to –24, exhibit a prominent positive correlation with ammonium nitrate leachates (plant ε Nd = 0.77 × leachate ε Nd – 3.83, R2 = 0.89). Plant samples do not show consistent variation between 87Sr/86Sr and εNd. The 206Pb/204Pb and 207Pb/204Pb ratios of bulk soils show a ~ 2 Ga trend, typical for Korean basement rocks. The Pb isotopic ratios of ammonium nitrate and acetic acid leachates match perfectly with each other (R2 = 0.99). The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of plant samples vary narrowly (19.2–17.9; 15.8–15.5; 39.0–38.0) and are distinctly different from those of bulk soils (24.4–17.9; 16.5–15.6; 42.5–37.9) and their leachates (23.1–17.7; 16.2–15.6; 41.0–38.1). Plant and soil data from this study and previous works were used to construct Sr and Nd isoscapes, employing interpolation models based on inverse distance weighting, simple kriging, empirical Bayesian kriging, and geology and topography-considered empirical Bayesian kriging regression prediction. These maps await validation through analysis of additional archives. Conclusions The isotope data obtained in this study highlight a strong geological control over bioavailable Sr and Nd, in contrast to a dominant environmental influence on bioavailable Pb. The Sr and Nd isoscapes presented here are potentially valuable for addressing archaeological or forensic inquiries in their current state. Nevertheless, the maps would benefit from additional refinement with increased sample density and enhanced interpolation models.

Abstract Immobilization of graphene quantum dots (GQDs) on a solid support is crucial to prevent GQDs from aggregation in the form of solid powder and facilitate the separation and recycling of GQDs after use. Herein, spatially dispersed GQDs are post-synthetically coordinated within a two-dimensional (2D) and water-stable zirconium-based metal–organic framework (MOF). Unlike pristine GQDs, the obtained GQDs immobilized on 2D MOF sheets show photoluminescence in both suspension and dry powder. Chemical and photoluminescent stabilities of MOF-immobilized GQDs in water are investigated, and the use of immobilized GQDs in the photoluminescent detection of copper ions is demonstrated. Findings here shed the light on the use of 2D MOFs as a platform to further immobilize GQDs with various sizes and distinct chemical functionalities for a range of applications.

The expansion or compression of gas confined in a piston-and-cylinder device is a classic working example used for illustrating the First and Second Laws of Thermodynamics. The balance of energy and entropy enables the estimation of a number of thermodynamic properties. The entropy generation (also called entropy production) resulting from this process can also be used to determine the feasibility and reversibility of a process. In this work, we present an extended discussion involving quantitative analysis of the effects of friction between a piston and the interior wall of a cylinder. Our findings indicate that the friction force caused by the movement of the piston is a main source of entropy generation in this process. This explanation does not appear in most textbooks dealing with similar problems. We also discuss, from a quantitative perspective, the effects of friction on the dynamic physical and thermodynamic properties, including entropy generation. Our findings suggest that engaging students in a discussion related to piston-and-cylinder problems involving the effects of friction could provide valuable insight into entropy generation in practical applications.

Efforts to make effective use of technology offer a promising direction for science education research. In this study, we investigated how a teacher and students used an inquiry-based, visualization-focused chemistry unit. The chemistry unit was designed for American students and takes advantage of dynamic, interactive computer visualizations. Features of the unit enable innovative learning activities such as online construction and critiquing of dynamic visualizations of chemical reactions. These kinds of activities are unfamiliar to teachers and students who are used to traditional teacher-centered instruction. We investigated how a teacher in Taiwan customized and implemented the unit to address the needs of her teaching in Taiwan, and what the impact of the unit was on the students' understanding of chemical reactions. The results provide insights into the impact of innovative practices that new technology brings to local classrooms, and reflections on the adaptation of reform-based science instruction are made.

In this study, we investigated how students used a drawing tool to visualize their ideas of chemical reaction processes. We interviewed 30 students using thinking-aloud and retrospective methods and provided them with a drawing tool. We identified four types of connections the students made as they used the tool: drawing on existing knowledge, incorporating dynamic aspects of chemical processes, linking a visualization to the associated chemical phenomenon, and connecting between the visualization and chemistry concepts. We also compared students who were able to create dynamic visualizations with those who only created static visualizations. The results indicated a relationship between students constructing a dynamic view of chemical reaction processes and their understanding of chemical reactions. This study provides insights into the use of visualizations to support instruction and assessment to facilitate students' integrated understanding of chemical reactions.

Multi-level adaptation in end-user development (EUD) is an effective way to enable non-technical end users such as educators to gradually introduce more functionality with increasing complexity to 3D virtual learning environments developed by themselves using EUD approaches. Parameterization, integration, and extension are three levels of adaptation ranging from straightforward to complex in terms of what end users have to understand in order to develop functional software applications, all within reach of end users without special training on programming. A 3D educational application EUD system prototype, "iVirtualWorld," has been expanded to support 3D virtual chemistry experiments generation using these three levels of EUD adaptation. An evaluation has been conducted on 18 participants from the education domain, and the results confirmed ease-of-learn, ease-of-use, and usefulness of this solution. Contributions of this paper are: (1) a paradigm for applying EUD technologies in 3D virtual learning environment creation; (2) an easy-to-use tool for educators to build customized virtual chemistry experiments; and (3) empirical assessment data for the multi-level adaptation solution.

ABSTRACT: An effective and facile method of generating nitrogen-doped carbon dots (N-CD) by microwave irradiation is presented in this study. A precursor, succinic acid (SA), and a nitrogen source, bis-(3-aminopropyl)-amine (BAPA), were used to obtain N-CD. A precious quantum yield (QY) of 49.0% was obtained from the preparation of N-CD, which was well-soluble in water. The N-CD material was highly selective and sensitive for the detection of nickel ion (Ni2+), with a detection limit of 0.26 μM and a linear concentration range of 5-175 μM. The quenching of the N-CD by the presence of Ni2+ was referred to formation of complexes because of the interaction of Ni2+ on the N-CD. Hence, the proposed study has great promise regarding Ni2+ detection in broad applications. Keywords: Microwave, Ni2+, nitrogen-doped carbon dots.