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Project-based learning is widely used in organic laboratories. This goal-oriented and inquiry-based learning model complements student-centered training. Such models focus on complicated issues or real-world problems on the frontier of chemistry. Students progress through three project phases: preproject, during the project, and postproject. Herein, we combined organic synthesis, electrochemistry, and green chemistry to improve students' understanding of organic reactions and mechanisms and exposed them to a new method of organic synthesis, which is electrochemistry. Moreover, we integrated the concept of green chemistry into the study of organic chemistry, and student assessment indicated substantial improvement in the understanding of this concept. Students designed a simple electrochemical reactor and accomplished the synthesis of (±)-muscone. Meanwhile, student competencies were comprehensively improved. The project included a literature review, experimental procedures, and essay writing. Overall, responses from students regarding the project experience were highly affirming.

Does invention belong in the chemistry classroom? This article attempts to answer this question by describing how invention education first took root in a chemistry class at Ridgewood High School in Ridgewood, NJ, and then expanded to other students with diverse interests to find a solution to two worldwide problems: satisfying the need for safe drinking water and reducing plastic waste. Specifically, it describes the students' journey step-by-step during the COVID-19 pandemic to invent a self-sanitizing and sustainable Solar Aqua Tech water bottle. The concept underlying this invention was to quickly produce hydrogen peroxide (H[subscript 2]O[subscript 2]), a well-known sanitizing agent, on-demand within the confines of a bottle using only water, dissolved oxygen (O[subscript 2]), and solar power to eliminate pathogens in untreated water. Students had to convert this chemistry classroom concept into reality without a prescription and without knowing if their goal was even attainable. Since the journey did not take a linear path but veered in different directions as unexpected problems arose, the students sought guidance from academics, mentors, and local experts. Along the way, they acquired new knowledge with deepened understanding and overarching perspectives. Success was achieved only after many setbacks. In the end, the sense of accomplishment for finding a solution to two global problems instilled confidence in the students that, with empathy, perseverance, and resilience, they are equipped with essential skills to tackle 21st-century challenges. Invention, therefore, can be a valuable complement to the standard chemistry curriculum and is unparalleled in sparking a lifelong passion for learning.

In this laboratory experiment, the synthesis and characterization of H[subscript 5]PV[subscript 2]Mo[subscript 10]O[subscript 40]@Cu[subscript 3](BTC)[subscript 2] (denoted as NENU[subscript -9], H[subscript 3]BTC = 1,3,5-benzenetricarboxylic acid) and its application in fuel desulfurization were performed. This experiment is designed for advanced undergraduate students majoring in chemistry. In this experiment, students experience the universal procedures of solution syntheses, get knowledge of several modern instrumental techniques (PXRD, FTIR, SEM, and GC) widely utilized in chemical research, and learn the general procedure of heterogeneous catalytic reaction. Upon the completion of the experiment, not only was students' teamwork spirit cultivated by data-sharing and discussion in their assigned group, but also their environmental protection awareness was stimulated by performing a catalytic oxidative desulfurization reaction, a potential technology that may reach the goal of reducing sulfur oxide emissions. Moreover, students' basic chemistry knowledge (inorganic, coordination, organic, and analytical chemistry) was consolidated by using it to analyze experimental phenomena and results.

Chemistry is a subject which involves a number of abstract concepts, making it a difficult and frustrating learning process for many students. Educators and researchers believe that technology could provide an opportunity to address this problem. However, it is challenging to find a model for appropriately and successfully integrating technology into chemistry education. Therefore, in this study, a review was conducted on the technology-enhanced chemistry learning studies published in Social Science Citation Index (SSCI) journals from 2010 to 2019. This study searched the target articles from the Web of Science (WOS) database and excluded those studies that did not adopt a comparative research design. Finally, 60 studies were included in this research trend analysis. A coding scheme was developed for the types of technology, the types of learning tools, the roles of technology in chemistry learning, learning topics, learning environments, participants, research designs, and the learning outcomes the researchers evaluated. From the analysis results, it was found that (1) inorganic chemistry and physical chemistry courses were the main learning topics, while the formal classroom was most often referred to as the research setting. The most frequently discussed issue was students' learning achievement. (2) Regarding technology integration, offering students learning content through personal computers was the main activity mode. The technology was used for lower-level implementation, that is, providing supplementary materials for students. (3) Finally, using keyword analysis, it is possible to extract the recent concerns of the researchers, and from the results of the study, it is clear that the researchers are placing increasing emphasis on learners' experience and skill development in the learning process. Accordingly, this study highlights the features of the research trends and then provides suggestions for researchers in the technology-enhanced chemistry learning field.

An integrated and research-focused laboratory experiment is developed to introduce the "antenna effect" occurring in luminescent lanthanide complexes to students. Students synthesized a lanthanide metal-organic framework (Ln-MOF) with the formula of [Eu(BTPCA)(H O)]·2DMF·nH[Subscript 2]O (Eu-BTPCA, H[subscript 3]BTPCA = 1,1',1?-(1,3,5-triazine-2,4,6-triyl)tripiperidine-4-carboxylic acid) by the solvothermal method and characterized its structure by powder X-ray diffraction. They then measured the luminescence spectrum of Eu-BTPCA and compared it with that of EuCl[subscript 3]. Finally, students performed the luminescent sensing studies to metal ions. This experiment lets students gain the first-hand experience of solvothermal syntheses of MOFs and introduces essential scientific research approaches to students as well as exposes students to modern instrumental techniques for chemical research. Most importantly, through this experiment and its outcomes analyses, students can better understand the "antenna effect" and witness its application in metal ion luminescent sensing.

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.

This paper describes a method for determination of trihalomethanes (THMs) in drinking water via solid-phase microextraction (SPME) GC/MS as a means to develop and improve student understanding of the use of GC/MS for qualitative and quantitative analysis. In the classroom, students are introduced to SPME, GC/MS instrumentation, and the use of MS data for compound identification and quantification through traditional lectures and in-class problem solving. In the lab, they are introduced to GC/MS tuning and method development, learn how to use the GC/MS data system, and apply their knowledge to identify and quantify THMs in tap water samples. The method for this application is relatively simple, fast, and effective, and is based on the use of autosampler, SPME headspace sampling, a GC quadrupole ion trap MS instrument, and fluorobenzene as an internal standard. Data from analyses of standards demonstrated 1 ppb LODs, good linearity in the 5-100 ppb range, RSDs of 6% or lower, and good recoveries from spikes of a tap water sample. This method as described is appropriate for environmental analysis, instrumental analysis, or quantitative analysis courses. It provides students with hands-on experience in the use of SPME-based sampling methods and GC/MS for reliable identification and accurate quantitative analysis at low ppb levels.

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.

Abstract The development of mild and practical strategies to produce value-added fine chemicals directly from inexpensive and readily available commodity chemicals is actively pursued by chemists. However, the application of feedstock chemical dichloromethane (DCM) as the C1 source in organic synthesis is still in its infancy. Herein, we describe a multicomponent strategy for the chemoselective synthesis of valuable 1,4,2-dioxazoles by using DCM as a C1 source. Critical to the success of this process is tuning of the type of nucleophiles to inhibit the easily-occurring side reactions. This approach features mild and simple conditions, excellent chemoselectivity, metal free, and broad substrate scope covering different types of nucleophiles. Furthermore, its synthetic utility is further demonstrated by the preparation of deuterated 1,4,2-dioxazoles, the late-stage functionalization of complex molecules and large-scale synthesis. Preliminary mechanistic studies indicate the dual roles of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as both a proton scavenger and a nucleophilic catalyst. This work provides not only a platform for DCM application, but also an excellent complementary strategy to the established 1,4,2-dioxazoles synthesis.

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.

Autostereoscopic displays employing lenticular sheets have broad applications due to the high transmittance of lenticular sheet. However, due to the restriction of lens array design and processing, the imperfect image of lenses can reduce the quality experience of autostereoscopic displays. Stereo depth is one of the qualities of experience parameters, which relates to the three-dimensional effect. Therefore, to quantize the reduction effect of stereo depth caused by lens aberration is of great value. In this paper, we implement a binocular model of an autostereoscopic display system with lens array to analyze this effect, which is different from the previously used monocular model. Two receivers in the positions of viewer’s eyes are set on the viewing plane, and a similar factor is defined to evaluate the difference of light spots perceived by the two receivers. When the similar factor exceeds a certain value, the two spots cannot be fused in the brain, thus restricting the perceived stereo depth. Both in simulation and experiment, a sudden decrease of the similar factor is observed when the viewing angle exceeds 16°. In the subjective experiment, all the sixteen viewers feel a sudden decrease of stereo depth when the viewing angle exceeds 16°, which further verifies the validity of the model. The model and the method are significant for improving the viewing experience of autostereoscopic displays and providing a guidance on autostereoscopic display system designing.

Soldering of ceramics/metals using an inactive commercial solder with the advantage of low cost has wide application prospects. The dissolution behavior of base metal could not be quantified, which has been a basic issue for the joining design. This work investigated the dissolution of the solid Al in liquid Sn with and without the ultrasound. The physical model for the dissolving process was established based on the experiments. The relationship equation of the average concentration of Al (Ca) and soldering time was derived by using the Nernst-Brunner principle. The key parameters of limiting solubility (C0L) and dissolution rate constant (K) were obtained through dissolving experiments of liquid Sn to solid Al. The calculation results show that the effect of soldering temperature, and thickness Sn layer on the Al concentration (Ca) and dissolution rate (dCa/dt) under ultrasound is weaker than that without ultrasound. Compared to the condition without ultrasound, the value K, the maximum value of Ca and dCa/dt was increased by 5.8 times, 4.5 times, and 52 times at 250 °C under the ultrasound action, respectively, and the activation energy of dissolution was reduced by 41 %. The mechanism of ultrasonically accelerating dissolution of the solid Al by the liquid Sn has been revealed by using the bubble dynamics principle. It will provide a guideline for the design of soldering ceramics/metals using an inactive commercial solder.

Scientific literacy and authenticity have gained a lot of attention in the past few decades worldwide. The goal of the study was to develop various authentic assessments to investigate students' scientific literacy for corresponding to the new curriculum reform of Taiwan in 1997. In the process, whether ninth graders were able to apply school knowledge in real-life problems was also investigated. Over the course of our two-year study, we developed authentic assessments to investigate a stratified random sampling of 1,503 ninth graders' levels of scientific literacy, including scientific cognition, process skills, application of science, habits of mind, nature of science, and attitude towards science. The purpose of this article is to discuss three different formats of authentic assessments: multiple-choice, open-ended, and hands-on test items, which we developed to investigate scientific cognition. To validate the three formats of authentic assessments, students' performance on these three assessments were compared with the science section of Taiwan's Academic Attainment Testing (STAAT), and the values of Pearson correlation coefficient were all at the significant level, ranging from 0.205 to 0.660 (p less than 0.01). We found that our three authentic assessments were better in evaluating students' authentic abilities in science than standardized tests (such as STAAT). Further authentic assessments, particularly the hands-on activity, benefited low-achieving students. Concerning the common themes tested in the authentic assessments, students performed better in a multiple-choice test than an open-ended test on electricity and heat and temperature. In addition, two themes of chemical reactions and reactions of acid and base with indicators were performed best in a hands-on test than in the other two tests. In this article, we provide evidence that authentic assessments could be developed in different formats to investigate students' scientific cognition as part of the national test. Of these formats, the multiple-choice, open-ended, and hands-on test items are all shown to be sensitive in their evaluation of students' cognition in science. (Contains 5 tables and 4 figures.)

A project needs to be able to anticipate potential threats, respond effectively to adverse events, and adapt to environmental changes. This overall capability is known as project resilience. In order to make efficient project decisions when the project is subjected to disruption, such as adjusting the project budget, reformulating the work plan, and rationalizing the allocation of resources, it is necessary to quantitatively understand the level of project resilience. Therefore, this paper develops a novel approach for forecasting project performance, illustrating the changes in performance levels during the disruption and recovery phases of a project and thus quantitatively assessing project resilience. While there are several methods for assessing project resilience in existing research, the majority of assessment approaches originate from within projects and are highly subjective, which makes it difficult to objectively reflect the level of project resilience. Moreover, the availability of project samples is limited, which makes it difficult to forecast the level of project performance. In view of the fact that the Reference Class Forecasting (RCF) technique avoids subjectivity and the Radial Basis Function (RBF) neural network is known to be better at forecasting small sample datasets, this paper therefore combines the RCF technique and the RBF neural network to construct a model that forecasts the project performance of the current project after experiencing a disruption, further assessing the level of the project resilience. Specifically, this paper first presents a conceptual model of project resilience assessment; subsequently, an RBF neural network model that takes into account project budget, duration, risk level of disruption, and performance before disruption based on the RCF technique is developed to forecast project performance after experiencing disruption; and finally, the level of project resilience is assessed through calculating the ratio of recovery to loss of project performance. The model is trained and validated using 64 completed construction projects with disruptions as the datasets. The results show that the average relative errors between the forecast results of schedule performance index (SPI) and the real values are less than 5%, and the R2 of the training set and the testing set is 0.991 and 0.964, respectively, and the discrepancy between the forecasted and real values of project resilience is less than 10%. These illustrate that the model performs well and is feasible for quantifying the level of project resilience, clarifying its impact on project disruption and recovery situations, and facilitating the decision-makers of the project to make reasonable decisions.

Owing to their endocrine disruption effect, the hormone levels in animal-source food and medicines need to be efficiently and accurately quantified by a reliable analytical method. In the current study, by using a homonuclear decoupling and heteronuclear single quantum correlation (HSQC) experiment, coupled with non-uniform sampling (NUS) that was used to shorten the experimental time, we developed a method to quantify 10 hormone residues in animal-source products. This method was validated following the guidelines of USP–NF 2022. The application of the homonuclear decoupling (HD) technique to conventional HSQC yielded 2D spectra that exhibited excellent signal separation and specificity. For all the tested hormones, good linearity with correlation coefficients of more than 0.99 was observed in the linear range of 0.2–6 mg/0.6 mL. Satisfactory precision and recoveries of spiked animal samples were also obtained. Finally, the method was applied in residue determination of 10 hormones in real animal-source samples at the ug/g level.

Automatic coal-rock recognition (ACRR) is of considerable theoretical and practical significance for unmanned coal mining. To the best of our knowledge, this is the first study to assess laser-induced breakdown spectroscopy (LIBS) combined with an artificial neural network (ANN) for automatic coal-rock recognition. Each sample in this study was subjected to LIBS testing and spectrum collection 20 times in the air, and the average value was taken as the LIBS data. Spectral data were optimized and dimensionality reduction was performed using partial least-squares discriminant analysis (PLS-DA). The 10 selected wavelength lines were used to construct a simplified spectral model (SSM). The ANN based on SSM was designed to classify the coal and rock. The results demonstrated that LIBS combined with an ANN has a high recognition accuracy rate, providing a rapid and accurate coal-rock recognition method for unmanned coal mining., Intelligent coal mining and processing are important for sustainable and safe coal mining (1,2). Automatic coal-rock recognition (ACRR) is one of the key technologies for intelligent coal mining and processing. [...]

Background Glycated hemoglobin, or hemoglobin A1c (HbA1c), serves as a crucial marker for diagnosing diabetes and monitoring its progression. We aimed to assess the interference posed by common Hb variants on popular HbA1c measurement systems. Methods A total of 63 variant and nonvariant samples with target values assigned by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)-calibrated methods were included. We assessed 6 methods for measuring HbA1c in the presence of HbS, HbC, HbD, HbE, and fetal hemoglobin (HbF): 2 cation-exchange high-performance liquid chromatography (HPLC) methods (Bio-Rad D-100 and HLC-723 G8), a capillary electrophoresis (CE) method (Sebia Capillarys 3 TERA), an immunoassay (Roche c501), an enzyme assay system (Mindray BS-600M), and a boronate affinity method (Primus Premier Hb9210). Results The HbA1c results for nonvariant samples from the 6 methods were in good agreement with the IFCC-calibrated method results. The Bio-Rad D-100, Capillarys 3, Mindray BS-600M, Premier Hb9210, and Roche c501 showed no interference from HbS, HbC, HbD, and HbE. Clinically significant interference was observed for the HLC-723 G8 standard mode. Elevated HbF levels caused significant negative biases for all 6 methods, which increased with increasing HbF concentration. Conclusion Elevated levels of HbF can severely affect HbA1c measurements by borate affinity, immunoassays, and enzyme assays. [ABSTRACT FROM AUTHOR]

In a previous study, polyphyllin III, an important natural dioscin ingredient, was bonded to silica particles using the 'one-pot method' for preparing a stationary phase, called SP-D. SP-D was further modified to produce two stationary phases, namely the phenyl isocyanate-dioscin (Phe-D) and 3,5-dimethyl phenyl isocyanate-dioscin bonded silica stationary phase (DMP-D), respectively. The Phe-D and DMP-D were evaluated by achiral and chiral analytes. The high performance liquid chromatography (HPLC) method was optimized and applied to the analysis of the main active ingredient, polyphyllins, that were contained in gongxuening capsules, a traditional Chinese medicine (TCM) widely used to treat gynecological diseases. The two synthesized stationary phases were also applied to the separation of the amino acid (AA) enantiomers. For this study, 10 [alpha]-AAs (lysine, leucine, cysteine, arginine, isoleucine, threonine, serine, valine, alanine, and histidine) were selected and studied for chiral separation using Phe-D and DMP-D stationary phases. In this study, 10 observed AA enantiomers were separated to different degrees on at least one stationary phase whereas four AAs were enantioseparated on both Phe-D and DMP-D. These results indicated that the two synthesized stationary phases have potential applicability in quality control (QC) of TCM and chiral separation as well as offering a new application choice for analyses of natural products., As the pharmaceutical and natural medicine industries continue to evolve, new separation issues posed by various samples need to be resolved. As a result, the demand for more reversed-phase high [...]

Fourier transform infrared spectroscopy (FT-IR) was used to examine 20 batches of the mineral medicine natrii sulfas (NS) to establish its reference point and fingerprint it using the common peak patterns in the spectra of the samples. The correlation coefficient, corner cosine, and peak location averages were then used to evaluate the similarities between the spectra. The fingerprint was verified through cluster analysis of four batches of the mineral medicine. Finally, it was confirmed that fingerprinting is a facile, rapid, and accurate method for the quality control of NS., Natrii sulfas (NS) is a transparent and lustrous crystal that primarily contains sodium sulfate decahydrate and is crystallized from sulfate minerals. NS is used as a medicine to help relax [...]