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This study explored the electroencephalography (EEG) dynamics during a chemistry-related decision-making task and further examined whether the correctness of the decision-making performance could be reflected by EEG activity. A total of 66 undergraduate students' EEG were collected while they participated in a chemistry-related decision-making task in which they had to retrieve the relevant chemistry concepts in order to make correct decisions for each task item. The results showed that it was only in the anterior cingulate cortex (ACC) cluster that distinct patterns in EEG dynamics were displayed for the correct and incorrect responses. The logistic regression results indicated that ACC theta power from 300[Formula: see text]ms to 250[Formula: see text]ms before stimulus onset was the most informative factor for estimating the likelihood of making correct decisions in the chemistry-related decision-making task, while it was the ACC low beta power from 150[Formula: see text]ms to 250[Formula: see text]ms after stimulus onset. The results suggested that the ACC theta augmentation before the stimulus onset serves to actively maintain the relevant information for retrieval from long-term memory, while the ACC low beta augmentation after the stimulus onset may serve the function of mapping the encoded stimulus onto the relevant criteria that the given participant has held within his or her mind to guide the decision-making responses.

Many studies have reported that frontal theta and posterior alpha activities are associated with working memory tasks. However, fewer studies have focused on examining whether or not the frontal alpha or posterior theta can play a role in the working memory task. This study investigates electroencephalography (EEG) dynamics and connectivity among different brain regions' theta and alpha oscillations. The EEG was collected from undergraduate students (n = 64) while they were performing a Sternberg-like working memory task involving chemistry concepts. The results showed that the frontal midline cluster exhibited sustained theta augmentation across the periods of stimulus presentations, maintenance, and probe presentation, suggesting that the frontal midline theta might associate with facilitating the central execute function to maintain information in the working memory. Study of the central parietal and the occipital clusters revealed a sequence of theta augmentation followed by alpha suppression at constant intervals after the onset of stimulus and probe presentations, suggesting that the posterior theta might be associated with sensory processing, theta gating, or stimulus selection. It further suggests that the posterior alpha event-related de-synchronization (ERD) might be linked to direct information flow into and out of the long-term memory (LTM) and precede stimulus recognition. An alternating phasic alpha event-related synchronization (ERS) and ERD following the 1st stimulus and probe presentations were observed at the occipital cluster, in which alpha ERS might be linked to the inhibition of irrelevant information., (© 2013.)

The tirandamycins (TAMs) are a small group of Streptomyces-derived natural products that target bacterial RNA polymerase. Within the TAM biosynthetic cluster, trdE encodes a glycoside hydrolase whose role in TAM biosynthesis has been undefined until now. We report that in vivo trdE inactivation leads to accumulation of pre-tirandamycin, the earliest intermediate released from its mixed polyketide/nonribosomal peptide biosynthetic assembly line. In vitro and site-directed mutagenesis studies showed that TrdE, a putative glycoside hydrolase, catalyzes in a highly atypical fashion the installation of the Δ(11,12) double bond during TAM biosynthesis.

A novel Cu (II) magnetic ion-imprinted polymer (MIIP) was synthesized by surface imprinting technique combined with a sol-gel process. The adsorbent of Cu (II)-MIIP shows higher capacity and selectivity than that of magnetic non-imprinted polymers (MNIP). Adsorption capacities of Cu (II)-MIIP and MNIP are 24.2 and 5.2mg/g for Cu (II) ions, respectively. The selectivity coefficients of the Cu (II)-MIIP for Cu (II)/Zn (II) and Cu (II)/Ni (II) are 91.84 and 133.92, respectively. Kinetics studies show that the adsorption process obeys pseudo-second-order rate mechanism with an initial adsorption rate of 132.48 for Cu (II)-MIIP and 2.41mgg(-1)min(-1) for MNIP. In addition, no obvious decrease was observed after up to five adsorption cycles, indicating that the Cu (II)-MIIP is of high stability., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Over the past 30 years, the field of thermal analysis of organic peroxides has become an important issue in chemical engineering departments, safety departments, and in companies working with polymerization, petrifaction process, and so on. The contributions of thermal analysis to the evaluation and prediction of the runaway reactions have been important for decreasing or preventing a hazard, such as fire or explosion accident. This study was carried out using differential scanning calorimetry (DSC) to evaluate the kinetic and safety parameters in isothermal and non-isothermal conditions, for instance, temperature of no return (T(NR)), self accelerating decomposition temperature (SADT), time to maximum rate (TMR), activation energy (E(a)), frequency factor (A), reaction order (n), and reaction heat (ΔH), in terms of the hazardous material of 1,1,-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane (TMCH) 88 mass%. On the basis of this study, we demonstrated that TMCH 88 mass% must be well controlled in the manufacturing process due to the unstable structure of O-O, which releases a great quantity of heat, higher than 1300 J/g under decomposition. Results of this study could contribute to the relevant plants adopting TMCH 88mass% in a process, in order to prevent a fire or explosion accident from happening., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 µm and an average porosity of 48.26 ± 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

Sucrose fatty acid esters were synthesized by the transesterification of sucrose with aliphatic esters under ultrasound irradiation in good yield (73%). The optimum reaction conditions for the transesterification reaction include a molar ratio of sucrose to fatty acid ethyl ester of 2:1 and the use of a 13%mol anhydrous K(2)CO(3) catalyst. The optimum reaction temperature was set at 70 degrees C, the optimum reaction time was 2h, and the optimum reaction pressure was 11kPa. The reaction had excellent monoester selectivity. The proportion of monoester (6-monoester+6'-monoester) in the purified products was up to 92-95% via flash column chromatography over silica gel, the ratios of 6-monoester/6'-monoester are 2.1-2.7, and the sucrose monoesters were identified by HPLC-MS, NMR and IR.

Three series of thioglycosyl donors differing only in their respective aglycon substituents within each series have been prepared as representatives of typical glycosyl donors. The relative anomeric reactivities of these donors were quantified under competitive glycosylation conditions with various reaction time, promoters, solvents and acceptors. Over three orders of magnitude reactivity difference were generated by simple transformation of the para-substituent on the aglycon with methanol as the acceptor, while chemoselectivities became lower with carbohydrate acceptors. Excellent linear correlations were attained between relative reactivity values of donors and sigma(p) values of the substituents in the Hammett plots. This indicates that the glycosylation mechanism remains the same over a wide range of reactivities and glycosylation conditions. The negative slopes of the Hammett plots suggested that electron donating substituents expedite the reactions and the magnitudes of slopes can be rationalized by neighboring group participation as well as electronic properties of the glycon protective groups. Within the same series of donors, less nucleophilic acceptors gave smaller slopes in their Hammett plots. This is consistent with the notion that acceptor nucleophilic attack onto the reactive intermediate is part of the rate limiting step of the glycosylation reaction.

Novel concepts are proposed for interpenetrating polymer networks (IPNs) that can be used in biomaterials responsive to multiple types of environmental stimuli. The IPNs can be a route to the tunable biomaterials whose chemical structure and/or morphology can be adjusted to the type of task to be performed. The significance of utilizing new types of processes in polymer chemistry such as the Suzuki polycondensation and living/controlled radical polymerizations to the possibility of extending/modifying component networks in the IPNs and fine-tuning their properties is emphasized. Incorporation of nanofillers into IPNs and application of monomers other than traditional alkylacrylamides as a way to enhance versatility of IPNs are also considered.

CZE with UV-absorption detection has been used for the separation and determination of enkephalin-related peptides. The experimental conditions, such as pH and concentration of running buffer, applied voltage, injection method, and time, were investigated in detail. Excellent separation efficiency could be obtained for ten enkephalin-related peptides with a 50 microm (ID) x 58 cm capillary using sodium dihydrogen phosphate as the running buffer (pH 3.11) when 20 kV of applied voltage was used. The concentration detection limits were found to be in the range of 0.31-1.94 microg/mL (defined as S/N = 3). The proposed method has been applied to analyze the spiked cerebrospinal fluid (CSF) sample, and the results showed that CZE is a powerful technique for separation and detection of the above biological peptides.

Redox reaction is a core chemical concept. However, its abstract nature makes it very difficult for students. Students' conceptual structure reflects their mastery of concepts, which helps teachers implement targeted educational strategies. This study aimed to explore the conceptual structures of redox reaction held by students (grades 10 to 12) by employing MDS and HCA. A total of 606 students participated, with 195 students in 10th grade, 202 in 11th grade, and 209 in 12th grade. The results indicated that three-dimensional solutions were appropriate for the conceptual structures of 10th and 12th graders, while 11th graders demonstrated two-dimensional solutions. All students grouped the 15 concepts related to redox reaction into two large clusters: metrology and the redox reaction process. Moreover, both 10th and 12th graders further subdivided the 15 concepts into four subclusters: metrology, oxidation process, reduction process, and chemical reaction. Students' conceptual structures were rational across all three grades. The conceptual structures of 10th and 12th graders were more refined than those of 11th graders, and there was no significant difference between the conceptual structures of 10th and 12th graders. 11th graders learned about electrochemistry and tended to confuse concepts related to redox reaction with those related to electrochemistry.

In the evolving landscape of higher education, challenges such as the COVID-19 pandemic have underscored the necessity for innovative teaching methodologies. These challenges have catalyzed the integration of technology into education, particularly in blended learning environments, to bolster self-regulated learning (SRL) and higher-order thinking skills (HOTS). However, increased autonomy in blended learning can lead to learning disruptions if issues are not promptly addressed. In this context, OpenAI's ChatGPT, known for its extensive knowledge base and immediate feedback capability, emerges as a significant educational resource. Nonetheless, there are concerns that students might become excessively dependent on such tools, potentially hindering their development of HOTS. To address these concerns, this study introduces the Guidance-based ChatGPT-assisted Learning Aid (GCLA). This approach modifies the use of ChatGPT in educational settings by encouraging students to attempt problem-solving independently before seeking ChatGPT assistance. When engaged, the GCLA provides guidance through hints rather than direct answers, fostering an environment conducive to the development of SRL and HOTS. A randomized controlled trial (RCT) was employed to examine the impact of the GCLA compared to traditional ChatGPT use in a foundational chemistry course within a blended learning setting. This study involved 61 undergraduate students from a university in Taiwan. The findings reveal that the GCLA enhances SRL, HOTS, and knowledge construction compared to traditional ChatGPT use. These results directly align with the research objective to improve learning outcomes through providing guidance rather than answers by ChatGPT. In conclusion, the introduction of the GCLA has not only facilitated more effective learning experiences in blended learning environments but also ensured that students engage more actively in their educational journey. The implications of this study highlight the potential of ChatGPT-based tools in enhancing the quality of higher education, particularly in fostering essential skills such as self-regulation and HOTS. Furthermore, this research offers insights regarding the more effective use of ChatGPT in education.

Chemistry academic engagement has received considerable attention for its role in enhancing students' learning and overall development. As a significant factor influencing students' chemistry improvement, research on chemistry academic engagement has emerged as a focal point. However, the methods to improve students' chemistry academic engagement remain limited until now. Therefore, this study aims to investigate the mechanisms of chemistry academic engagement, self-handicapping, chemistry academic buoyancy and teacher support, and offer suggestions to improve students' academic engagement. We assumed a moderated mediation model and evaluated all variables for twelve different schools in China (N = 3344, Grade 10), then analyzed the data with structural equation models (SEM). The results suggested that (1) self-handicapping in chemistry negatively predicted chemistry academic engagement; (2) chemistry academic buoyancy moderated the relationship between chemistry academic engagement and self-handicapping to a certain extent, and this indirect effect was significant irrespective of teacher support levels; (3) instrumental support moderated the mediating process in the academic buoyancy to academic engagement pathway; (4) teacher emotional support moderated the direct and indirect pathways of the mediating process from self-handicapping in chemistry to chemistry academic engagement. Finally, we analyzed the results of this research, highlighted its educational significance, recognized the limitations and made recommendations for further research.

Here we have shown the novel biosynthesis of silver nanoparticles (Ag NPs) encapsulated by chitosan polymers in the presence of Achillea millefolium aqueous extract (Ag NPs@CHI). The Ag ions were first embedded over the chitosan surface enriched with polar organofunctions like amines (NH2) and hydroxyls, and subsequently the ions were reduced green-metrically by the electron rich phytochemicals of the plant extract. After the synthesis numerous techniques, including the UV-vis spectrum, transmission electron microscopy, FE-SEM, EDS-elemental mapping, and ICP-AES, were used to study the physicochemical characteristics of the nanocomposite biomaterial. Next, we explored the material biologically in the anti-cutaneous squamous cell carcinoma effects against the corresponding cell lines like PM1, MET1, MET 4, SCC T9, SCC IC1MET, SCC IC19, SCC T8, and SCC T11. The related IC50 values of the nanocomposite against them were 182, 158, 177, 178, 177, 99, 62, and 183 µg/mL, respectively. The cytotoxicity in terms of percentage cell viability of cancer cells were decreased with the increase in the nanocomposite doses.

Abstract Isofagomine (IFG) and its analogues possess promising glycosidase inhibitory activities. However, a flexible synthetic strategy toward both C5a-functionalized IFGs remains to be explored. Here we show a practical synthesis of C5a-S and R aminomethyl IFG-based derivatives via the diastereoselective addition of cyanide to cyclic nitrone 1. Nitrone 1 was conveniently prepared on a gram scale and in high yield from inexpensive (−)-diethyl d-tartrate via a straightforward method, with a stereoselective Michael addition of a nitroolefin and a Nef reaction as key steps. A 268-membered library (134 × 2) of the C5a-functionalized derivatives was submitted to enzyme- or cell-based bio-evaluations, which resulted in the identification of a promising β-glucocerebrosidase (GCase) stabilizer demonstrating a 2.7-fold enhancement at 25 nM in p.Asn370Ser GCase activity and a 13-fold increase at 1 μM in recombinant human GCase activity in Gaucher cell lines.

Crystal materials are an important pillar of advanced technology. Among them, the preparation of large-sized single crystal materials is of great importance for their practical application. Herein, we select the well-known nonlinear optical crystal KH[subscript 2]PO[subscript 4] and impressive deep-blue colored crystal CuSO[subscript 4]·5H[subscript 2]O to design an integrated experiment on the growth of large-size single crystals. This experiment, which aims to introduce the basic concepts and techniques of crystal growth and characterization, was designed for undergraduate majors in chemistry and materials science. To deepen the understanding of the complicated theoretical knowledge and cultivate their interests in crystal growth, students prepared large-scaled crystals and then characterized and investigated the structures, morphologies, and properties of KH[subscript 2]PO[subscript 4] and CuSO[subscript 4]·5H[subscript 2]O. The common analytical methods involved in this lab course will help students to enhance their practical ability and thinking ability as well as initially cultivate their scientific research thoughts in the crystal material field.

Scientific methods have received widespread attention in recent years. Based on the analytical framework derived from Brandon's matrix consisting of four categories of scientific methods, this paper aims to conduct a content analysis to examine how the diversity of scientific methods is represented in college entrance chemistry examination papers from three exam boards in China. It was found that the percentages of the four categories of scientific methods in the examination papers varied significantly from each exam board, highlighting an imbalanced representation of scientific methods. Furthermore, among the four categories of scientific methods, non-manipulative parameter measurement (Non-MPM) accounted for the largest proportion in each examination paper, while the proportion of manipulative hypothesis testing (MHT) was very small, indicating that the practical chemistry items in China are less experimental. At the end of this paper, the implications of the findings and suggestions for further studies are discussed.

Production of high-quality multiple-choice questions (MCQs) for both formative and summative assessments is a time-consuming task requiring great skill, creativity and insight. The transition to online examinations, with the concomitant exposure of previously tried-and-tested MCQs, exacerbates the challenges of question production and highlights the need for innovative solutions. Several groups have shown that it is practical to leverage the student cohort to produce a very large number of syllabus-aligned MCQs for study banks. Although student-generated questions are well suited for formative feedback and practice activities, they are generally not thought to be suitable for high-stakes assessments. In this study, we aimed to demonstrate that training can be provided to students in a scalable fashion to generate questions of similar quality to those produced by experts and that identification of suitable questions can be achieved with minimal academic review and editing. Second-year biochemistry and molecular biology students were assigned a series of activities designed to coach them in the art of writing and critiquing MCQs. This training resulted in the production of over 1000 MCQs that were then gauged for potential by either expert academic judgement or via a data-driven approach in which the questions were trialled objectively in a low-stakes test. Questions selected by either method were then deployed in a high-stakes in-semester assessment alongside questions from two academically authored sources: textbook-derived MCQs and past paper questions. A total of 120 MCQs from these four sources were deployed in assessments attempted by over 600 students. Each question was subjected to rigorous performance analysis, including the calculation of standard metrics from classical test theory and more sophisticated item response theory (IRT) measures. The results showed that MCQs authored by students, and selected at low cost, performed as well as questions authored by academics, illustrating the potential of this strategy for the efficient creation of large numbers of high-quality MCQs for summative assessment.

GO was diffused into different size samples by dialysis. The experimental results showed that the GO in uniform size had better anti-friction and lubrication effects.

In this research, we have used a green approach to vanadium nanoparticle (NP) synthesis by the Salvia leriifolia watery extract. The NP characterization was performed by field emission scanning electron microscopy, fourier transform infrared, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The NPs materialized in spherical morphology with an average size of 26.26 nm. The antioxidant activity was assessed using 2-2 diphenyl-1-picrylhydrazil (DPPH) assay, while the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay was used to measure anti-colorectal cancer (against HCT-15‎, COLO 320, Caco-2, DLD-1‎, HT-29, and HCT-116 cell lines) and cytotoxicity (against HUVEC cell line) activity of vanadium NPs. Cancer cell line viability decreased dose dependently in the presence of V NPs. The half-maximal inhibitory concentration (IC50) values of V NPs were 149, 125, 173, 83, 131, and 105 µg/mL against Caco-2, COLO 320, DLD-1‎, HCT-15‎, HCT-116‎, and HT-29 cell lines, respectively. In radical scavenging activity, V NPs scavenged DPPH with the IC50 value of 33 µg/mL.

In recent years, solar-powered photocatalytic water splitting for hydrogen production has drawn great attention as a method to supply clean energy and reduce environmental pollution. This approach, driven by solar energy to synthesize hydrogen gas, is completely renewable and can be used to power hydrogen fuel cells to effectively solve the global energy problem, while only releasing environmentally benign water. Accordingly, popularizing this subject and educating students with the knowledge of this powerful technology are urgently needed. In this paper, Pt-loaded commercial titanium dioxide (P25) is used as the photocatalyst to explore the process of photocatalytic hydrogen evolution. A simple experimental demonstration is presented, integrating photocatalytic hydrogen production with a hydrogen fuel cell system in chemistry class. This experiment is suitable for use with undergraduate students as a systematic and basic laboratory experience or as a demonstration for primary/middle/high school students to stimulate their research interests in field of renewable energy. The principles and reaction mechanisms involved in both photocatalytic water splitting and hydrogen fuel cell operation, as well as the experimental design to link photocatalysis with fuel cells, are systematically discussed.

The rapid growth of personal electronics has promoted a surge of e-waste worldwide. Among the e-waste stream, waste printed circuit boards (WPCBs) contain a lot of recyclable valuable metals that can incentivize the recycling operation when recovered. This pedagogical exercise demonstrates a simple electrocatalytic metal recovery strategy that works at room temperature and atmospheric pressure. Students can complete the exercise within 1.5-2 h and get to learn about electrocatalytic reactions and their parameters. The reaction can be powered by a couple of 1.5 V AA batteries and an electrolyte chemically similar to automobile antifreeze. Using quotidian objects can help students connect their laboratory learning with their daily lives. In addition to teaching electrochemistry concepts, we hope this exercise can raise awareness of the substantial increase of e-waste in recent years.

The computer-aided drug design (CADD) course that spans biochemistry, computational chemistry, medicinal chemistry, and other cutting-edge sciences is considered an important course by pharmaceutical universities in China. The course teaches students how drugs bind to protein targets and exert their biological activities using computer tools, and covers the basic principles of drug development and optimization. Due to the lockdown and social distancing measures adopted during the coronavirus disease 2019 (COVID-19) pandemic, the CADD course in Shenyang Pharmaceutical University was briefly suspended. Thereafter, it was taught in the online mode by adopting a novel blended teaching method. Through a questionnaire survey and final report assessment, we found that blended teaching might provide an opportunity to stimulate greater motivation and interest in students as well as improve teaching effectiveness and learning outcomes of the course. This study describes how we conducted the CADD course during the COVID-19 period with the intention of providing a reference for other teachers to conduct similar courses.

Time-of-flight mass spectrometry is a commonly mass spectrometry technique that is widely used in biomedicine, environmental science and food science. The multiple reflection time-of-flight (MR-TOF) mass analyzer is a new type of mass analyzer with ultra-high mass resolution and has been used at institutions, such as Helmholtz Centre for Heavy Ion Research (GSI), European Organization for Nuclear Research (CERN) and High Energy Accelerator Research Organization (KEK) to measure short-lived ion masses, separate isobar and store ions. As the demand for use increasing, it is becoming important to improve the resolving power of MR-TOF mass analyzers. However, the optimization of the voltage parameters of MR-TOF mass analyzers is a high-dimensional, highly refined and non-linear problem, which is difficult to solve optimally by analytical method. In this study, a particle swarm optimization (PSO) algorithm-based method for optimizing the voltage parameters of MR-TOF mass analyzers was proposed. The method used an improved particle swarm optimization (IPSO) approach with a inertia weight decay strategy. The optimization method was tested on the SIMION ion optics simulation platform. Considering 133Cs+ ion with E=1.5 keV, δE=8.5 eV, δx=δy=1 mm, δα=δβ=1.5 mrad, a mass resolving power over 8.1×105 was achieved when Δt=0 ns and a mass resolving power over 5.0×105 was achieved when Δt=20 ns. IPSO optimized the best results to achieve the 2nd order focus of time with respect to energy for the MR-TOF mass analyzer, and the deviation of the ion′s half-turn time of flight was within 1.3×10-6. In 20 times experiments, IPSO improved the maximum results by 33%, the average results by 35% and the standard deviation by 29% compared with PSO optimization, providing better solution quality and stability. IPSO′s linear decay strategy effectively controlled the reduction of the voltage update step size and was able to meet the global search and refinement of the MR-TOF mass analyzer voltage parameter optimization problem. It had good convergence and convergence speed. This work provided a fast and effective method for optimizing the voltage parameters of the MR-TOF mass analyzer and helped to improve the performance of this analyzer. The results showed that the IPSO is able to obtain a limiting mass resolution of more than 810 000, which has better performance compared with the PSO. The method has the advantages of simple operation, fast optimization and better solution, which can provide a method reference for voltage optimization of MR-TOF mass analyzer and thus improve the development efficiency of MR-TOF mass analyzer.

Concrete linings containing cold joint defects may crack or detach under the aerodynamic fatigue loading generated by high-speed train operation, which posing a serious threat to the normal operation of high-speed trains. However, there is currently no simulation method specifically for fatigue damage of concrete linings containing cold joints. Based on the Roe-Siegmund cycle cohesive force model, a cohesive force fatigue damage elements were developed. A large dataset was constructed through numerical simulation software to build a BP neural network for back-calculated parameter of cohesive force fatigue damage elements. By combining experimental data, fatigue damage parameters corresponding to different pouring interval cold joints were back-calculated. These back-calculated parameters were then incorporated into the numerical model to compare simulation results with experimental results to validate the applicability of cohesive force fatigue damage elements and back propagation neural networks (BP neural network). The research results show that the difference between the fatigue life and fracture process calculated by numerical simulation and experimental data is small, verifying the applicability of the method proposed in this paper. The pouring interval directly affects the initial strength of the cold joint interface and the starting conditions of fatigue damage. The possibility of fatigue damage and fracture of concrete components containing cold joints increases with the increase of pouring interval, while the variability of fatigue life decreases with the increase of pouring interval. Interface strength and thickness are the main factors affecting the possibility of fatigue damage occurrence and the variability of fatigue life. The research results can be used to analyze the damage and cracking status of concrete linings containing cold joints under aerodynamic fatigue loading.

Facial expression recognition has wide application prospects in many occasions. Due to the complexity and variability of facial expressions, facial expression recognition has become a very challenging research topic. This paper proposes a Vision Transformer expression recognition method based on hybrid local attention (HLA-ViT). The network adopts a dual-stream structure. One stream extracts the hybrid local features and the other stream extracts the global contextual features. These two streams constitute a global–local fusion attention. The hybrid local attention module is proposed to enhance the network’s robustness to face occlusion and head pose variations. The convolutional neural network is combined with the hybrid local attention module to obtain feature maps with local prominent information. Robust features are then captured by the ViT from the global perspective of the visual sequence context. Finally, the decision-level fusion mechanism fuses the expression features with local prominent information, adding complementary information to enhance the network’s recognition performance and robustness against interference factors such as occlusion and head posture changes in natural scenes. Extensive experiments demonstrate that our HLA-ViT network achieves an excellent performance with 90.45% on RAF-DB, 90.13% on FERPlus, and 65.07% on AffectNet.

We introduced a microfluidic paper-based analytical device ([mu]PAD) to undergraduates majoring in nutrition education using a modified acid-base titration on paper microzones. After designing experiments for sample analysis using micro acid-base titration, students fabricated the devices and implement the experiment as designed. Then they designed and implemented a classical titration method to evaluate the analytical results obtained by micro acid-base titration. Finally, the students completed an instructional design for teaching at secondary or higher vocational colleges. This comprehensive experiment aims to expose students to [mu]PADs, ignite their passion in learning courses related to food analysis or chemistry, train their capabilities in designing an experiment, improve skills in instructional design, and facilitate education of [mu]PADs in secondary or higher vocational colleges. Fifty-three students majoring in nutrition education participated in this comprehensive experiment and completed instructional designs within 2 weeks (14 h) in the fifth semester. Positive feedback from students indicated that the learning objectives of this comprehensive experiment were met.

As of October 2022, the United Nations Office on Drugs and Crime (UNODC) Early Warning Advisory (EWA) has monitored over 1 150 new psychoactive substances (NPS) that had appeared in 137 countries and territories, including 76 substances that were notified for the first time in 2022. The increasing popularity of NPS has become a policy challenge and a major international concern, and poses potential risks for public health. Ketamine and ketamine analogues belong to β-keto-arylcyclohexylamines, which are classified into dissociative NPS due to their “dissociative anesthetic” effect. According to the monitoring data of the National Narcotics Laboratory, as of August 2022, ten ketamine structural analogues have been detected in China, including 2-(2-chlorophenyl)-2-(ethylamino) cyclohexan-1-one (NENK), 2-(3-methoxyphenyl)-2-(ethylamino) cyclohexan-1-one (MXE), 2-phenyl-2-(methylamino) cyclohexan-1-one (DCK), and 2-(2-fluorophenyl)-2-(methylamino)cyclohexan-1-one (2-FDCK), 2-(ethylamino)-2-phenylcyclohexan-1-one (2-oxo-PCE), 2-(methylamino)-2-(2-methylphenyl)cyclohexan-1-one (2-MDCK), 2-(ethylamino)-2-(2-fluorophenyl)cyclohexan-1-one (2-FXE), 2-(2-bromophenyl)-2-(methylamino)cyclohexan-1-one (2-BDCK), and 2-(ethylamino)-2-(thiophen-2-yl)cyclohexan-1-one (tiletamine), and 2-(ethylamino)-2-(2-methylphenyl)cyclohexan-1-one (deoxymethoxetamine). According to the structures, these compounds can be seen as structural analogues of ketamine with benzene ring replaced by fluorine, bromine, methyl and methoxy groups, or with methyl group on the nitrogen atom replaced by ethyl group, or with benzene ring replaced by furan group. NENK, MXE, DCK and 2-FDCK have already been included in the annexes of the law in China, while 2-oxo-PCE, 2-MDCK, 2-FXE, 2-BDCK, and tiletamine have not been listed in the regulation. In order to evade the supervision of the law, new types of ketamine analogues have been continuously produced and offered for sale on the NPS market. These emerging new compounds have posed a great challenge to the testing and identification ability of forensic science laboratories around the world. The knowledge of MS fragmentation pathway characteristics of known structure NPS is essential for the structure elucidation of new types of NPS. In order to investigate the mass fragmentation characteristics of ketamine analogues, NENK, MXE, DCK, 2-FDCK, 2-oxo-PCE, 2-MDCK, 2-FXE, 2-BDCK, and tiletamine were analyzed using gas chromatography-Orbitrap mass spectrometry (GC-Orbitrap-MS) and ultra-high performance liquid chromatography-quadrupole time of flight-mass spectrometry (UPLC-QTOF-MS). High-resolution mass spectra were obtained by electron impact (EI) and electrospray ionization collision-induced dissociation (ESI-CID), the structures and fragmentation pathways of main ions were deduced. The product ions of ketamine analogues were mainly formed by the loss of CO, C2H5·, C3H7·, C4H9·, C5H11·/C6H13· in EI mode, and were mainly formed by the loss of H2O, CH3NH2/C2H5NH2, CO, C4H6, C2H4O in ESI-CID mode. The ketamine analogues distinguishing features were summarized by investigating the high-resolution mass spectrometric characteristics, which can provide a reference for the identification of new ketamine analogues with similar chemical structures.

A green biosynthesis of silver nanoparticles (AgNPs) decorated Mentha longifolia root extract-functionalized graphene oxide (GO) nanohybrid material has been described. Initially, the Mentha longifolia root was coated on GO’s surface. The phytochemicals of the plant acted as reducing agent for reduction of silver ions and GO to form the rGO-Mentha/Ag nanocomposite. The nanocomposite was characterized using FE-SEM, EDX, FT-IR, TEM, elemental mapping, and XRD analysis. The cells treated with rGO-Mentha/Ag nanocomposite were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay for 48 h about the cytotoxicity and anti-human ovarian cancer properties on normal (HUVEC) and human ovarian cancer cell lines, i.e., SKOV3 and A2780. The IC50 of rGO-Mentha/Ag nanocomposite were 181.2 and 196.4 µg/mL against SKOV3 and A2780cell lines, respectively. The viability of malignant human ovarian cell line reduced dose-dependently in the presence of rGO-Mentha/Ag nanocomposite. After clinical study, rGO-Mentha/Ag nanocomposite can be introduced as a novel composite in the treatment of human ovarian cancer.

Morphology-dependent properties are significant in chemistry and material sciences. This laboratory experiment, designed for upper-division undergraduates in chemistry and related majors, emphasizes the concepts of the shape-controlled synthesis of crystal particles and the influences of crystal particle morphologies on their reaction performances. Cu[subscript 2]O particles with different morphologies, cubic and truncated octahedral, were synthesized under mild conditions. The resulting products were examined with XRD and SEM to characterize their phase components and surface morphologies. The activity differences of these products in the reduction of ferric thiocyanate solution, K[subscript (n-3)][Fe(SCN)[subscript n]], were measured and compared. The truncated octahedral Cu[subscript 2]O particles showed higher activity than the cubic ones, which is attributed to differences in their shapes and exposed facets. This experiment can help undergraduates realize that the performances of crystal particles are related not only to their structures and dimensions but also to their morphologies.