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In science education, chemistry is a discipline that involves macroscopic matter and microscopic particles. It is difficult for the traditional teaching approach to help learners comprehend abstract chemical knowledge. Researchers have attempted to use Virtual Reality (VR) to help learners realize meaningful knowledge via visualizing the learning content. However, merely engaging students in experiencing the scientific contexts is not enough. To fill this gap, the present study adopted Spherical Video-based Virtual Reality (SVVR) to create authentic learning contexts for learners, and proposed an exploration-based SVVR approach which aimed to promote students' understanding of abstract concepts and improve their competence of completing chemistry experiments. A quasi-experimental design was employed to evaluate the effectiveness of the proposed approach. A total of 136 junior high school students from three classes were recruited for the experiment. The experimental group adopted the exploration-based SVVR approach, control group I adopted the conventional SVVR approach, and control group II adopted traditional instruction. The results showed that the exploration-based SVVR approach not only improved students' learning achievement, but also increased their learning motivation, learning attitude, and creative thinking tendency. Besides, students adopting this approach had more positive behaviors, including finding problems, making assumptions, investigating and verifying, and discussion.

Introduction: Facial nerve injury significantly impacts both the physical and psychological] wellbeing of patients. Despite advancements, there are still limitations associated with autografts transplantation. Consequently, there is an urgent need for effective artificial grafts to address these limitations and repair injuries. Recent years have witnessed the recognition of the beneficial effects of chitosan (CS) and graphene in the realm of nerve repair. Dental pulp stem cells (DPSCs) hold great promise due to their high proliferative and multi-directional differentiation capabilities.Methods: In this study, Graphene/CS (G/CST) composite tubes were synthesized and their physical, chemical and biological properties were evaluated, then DPSCs were employed as seed cells and G/CST as a scaffold to investigate their combined effect on promoting facial nerve injury repair.Results and Disscussion: The experimental results indicate that G/CST possesses favorable physical and chemical properties, along with good cyto-compatibility. making it suitable for repairing facial nerve transection injuries. Furthermore, the synergistic application of G/CST and DPSCs significantly enhanced the repair process for a 10 mm facial nerve defect in rabbits, highlighting the efficacy of graphene as a reinforcement material and DPSCs as a functional material in facial nerve injury repair. This approach offers an effective treatment strategy and introduces a novel concept for clinically managing facial nerve injuries.

Critical thinking, a rational and open higher-order thinking mode in human cognition, is becoming imperative to success in modern life. Therefore, cultivating students' critical thinking has become a common goal of education reform worldwide. Teachers play a crucial role in cultivating students' critical thinking. However, existing studies have paid little attention to teachers, especially middle school teachers' knowledge and understanding of critical thinking. Therefore, this study aimed to explore the perspectives of ten Chinese middle school chemistry teachers on critical thinking using concept maps, thinking aloud, and in-depth interviews based on concept maps. Results showed that most of the teachers believed that critical thinking means reflection and questioning and requires evidence awareness. All teachers had a positive attitude towards critical thinking and believed that it can promote evidence awareness, problem solving, decision making, teaching evaluation, logic, and systematisation. Teachers recognised that critical thinking can be taught, and the major factors affecting the development of students' critical thinking were the environment, students themselves, teachers, evaluation, subject characteristics, and types of knowledge. Several strategies for developing students' critical thinking in chemistry teaching were proposed, including setting diversified and different types of chemistry courses, developing controversial curriculum themes in real situations, and implementing experimental, project-based, problem solving, and history-based teaching. In addition, this study showed that teachers and students promoted the development of critical thinking within one another. Further, this study demonstrated an effective methodology for probing individual subjective thoughts.

Aiming at the problem that dynamic targets in indoor environments lead to low accuracy and large errors in the localization and position estimation of visual SLAM systems and the inability to build maps containing semantic information, a semantic visual SLAM algorithm based on the semantic segmentation network DeepLabV3+ and LK optical flow is proposed based on the ORB-SLAM2 system. First, the dynamic target feature points are detected and rejected based on the lightweight semantic segmentation network DeepLabV3+ and LK optical flow method. Second, the static environment occluded by the dynamic target is repaired using the time-weighted multi-frame fusion background repair technique. Lastly, the filtered static feature points are used for feature matching and position calculation. Meanwhile, the semantic labeling information of static objects obtained based on the lightweight semantic segmentation network DeepLabV3+ is fused with the static environment information after background repair to generate dense point cloud maps containing semantic information, and the semantic dense point cloud maps are transformed into semantic octree maps using the octree spatial segmentation data structure. The localization accuracy of the visual SLAM system and the construction of the semantic maps are verified using the widely used TUM RGB-D dataset and real scene data, respectively. The experimental results show that the proposed semantic visual SLAM algorithm can effectively reduce the influence of dynamic targets on the system, and compared with other advanced algorithms, such as DynaSLAM, it has the highest performance in indoor dynamic environments in terms of localization accuracy and time consumption. In addition, semantic maps can be constructed so that the robot can better understand and adapt to the indoor dynamic environment.

Bioelectric phenomena play important roles in living organisms and are essential for regulating cellular and tissue behavior. Electroactive assemblies can facilitate tissue repair and/or regulate neural activity by simulating the tissue microenvironment, while providing electrical signals and biocompatible component niches. Self-powered nanogenerators including TENG and PENG are essential part in electroactive assemblies. Assemblies incorporating TENG or PENG can present the advantages of controllable morphology, portability, low cost, and flexibility, making them a new and promising research content in the biomedical field. Herein, we describe in detail the basic physical rules underlining electric field generations in assemblies, and discuss constructing rules and research progress of self-powered assemblies in tissue engineering. Their applications in the fields of bone tissue repair and regeneration, nerve modulation and injury repair, skin wound healing, and antibacterial are sequentially discussed. Finally, current challenges and possible solutions of self-powered artificial assemblies are discussed, expecting to promote the research efforts and advance the self-powered assemblies from laboratory to clinical applications.

Football is one of the most popular sports in the world, arousing a wide range of research topics related to its off- and on-the-pitch performance. The extraction of football entities from football news helps to construct sports frameworks, integrate sports resources, and timely capture the dynamics of the sports through visual text mining results, including the connections among football players, football clubs, and football competitions, and it is of great convenience to observe and analyze the developmental tendencies of football. Therefore, in this paper, we constructed a 1000,000-word Chinese corpus in the field of football and proposed a BiLSTM-based model for named entity recognition. The ALBERT-BiLSTM combination model of deep learning is used for entity extraction of football textual data. Based on the BiLSTM model, we introduced ALBERT as a pre-training model to extract character and enhance the generalization ability of word embedding vectors. We then compared the results of two different annotation schemes, BIO and BIOE, and two deep learning models, ALBERT-BiLSTM-CRF and ALBERT BiLSTM. It was verified that the BIOE tagging was superior than BIO, and the ALBERT-BiLSTM model was more suitable for football datasets. The precision, recall, and F-Score of the model were 85.4%, 83.47%, and 84.37%, correspondingly.

Sennae Folium (SF) has been consumed as a fat-reducing tea throughout the world due to its laxative effect. However, little attention has been paid to the impact of the specification grade classification on its quality. The present work aims to verify the rationality of the specification grade classification of SF and investigate the quality markers for distinction of different SF grades. Based on the use of ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method, and with the help of molecular networking, 60 compounds of the SF extracts were tentatively identified. 22 differential compounds were screened via chemometrics for distinguishing different grades of SF, including 8 sennosides and anthraquinones, 11 flavonoids, and 3 benzophenones. The strongest lipase inhibitory activity was identified in the extract taken from the green leaves. Correlation analysis of their chemical compositions and lipase inhibitory activity indicated that SF of the green leaf contained the highest amount of sennosides and showed the strongest lipid-lowering effect. In conclusion, the combination of molecular networking and spectrum-effect relationships showed that the specification grade classification of SF according to green leaf, yellow leaf, and diseased leaf was reasonable, and sennosides could serve as quality markers for distinguishing different grades of SF.

In 2012, the National Research Council and the American Chemical Society criticized many graduate education programs in the chemical sciences for not adequately preparing graduate students for the interdisciplinary careers that they will likely occupy. These and other reports anecdotally suggest that soft skills, broad versus specific knowledge, and interdisciplinary skills will make graduate students more competitive and better prepared for careers. However, relatively few efforts have been made to empirically evaluate and assess what specific knowledge and skills doctoral chemists require to be successful in their future careers. The qualitative study here expands on the previous anecdotal data by empirically identifying the knowledge and skills required for chemistry careers and compares those required in the academic and nonacademic sectors. A total of 31 U.S.-trained doctoral chemists from academia, industry, and government were interviewed about the activities they conduct on a day-to-day basis and the knowledge and skills required to successfully complete these activities. Twelve distinct, nonduplicative knowledge and skills that enable these chemists to successfully perform their jobs in different chemical sectors have been identified by thematic analysis of the interviews. Three inter-rater reliability (IRR) metrics were used to evaluate coding and demonstrate the trustworthiness of data. The results provide evidence that technical knowledge, communication, management, and several other skills are required for chemists in both academic and nonacademic job sectors, but these skills could be fundamentally different across sectors. The results of this study imply that different skill sets are required for diverse career pathways, and graduate programs should consider tailoring their programs for students accordingly.

Pasteurella multocida can cause goat hemorrhagic sepsis and endemic pneumonia. Respiratory epithelial cells are the first line of defense in the lungs during P. multocida infection. These cells act as a mechanical barrier and activate immune response to protect against invading pathogenic microorganisms. Upon infection, P. multocida adheres to the cells and causes changes in cell morphology and transcriptome. ATAC-seq was conducted to determine the changes in the chromatin open region of P. multocida-infected goat bronchial epithelial cells based on transcriptional regulation. A total of 13,079 and 28,722 peaks were identified in the control (CK) and treatment (T) groups (P. multocida infection group), respectively. The peaks significantly increased after P. multocida infection. The specific peaks for the CK and T groups were annotated to 545 and 6632 genes, respectively. KEGG pathway enrichment analysis revealed that the specific peak-related genes in the T group were enriched in immune reaction-related pathways, such as Fc gamma R-mediated phagocytosis, MAPK signaling pathway, bacterial invasion of epithelial cells, endocytosis, and autophagy pathways. Other cellular component pathways were also enriched, including the regulation of actin cytoskeleton, adherent junction, tight junction, and focal adhesion. The differential peaks between the two groups were subsequently analyzed. Compared to those in the CK group, 863 and 11 peaks were upregulated and downregulated, respectively, after the P. multocida infection. Fifty-six known transcription factor motifs were revealed in upregulated peaks in the P. multocida-infected group. By integrating ATAC-seq and RNA-seq, some candidate genes (SETBP1, RASGEF1B, CREB5, IRF5, TNF, CD70) that might be involved in the goat bronchial epithelial cell immune reaction to P. multocida infection were identified. Overall, P. multocida infection changed the structure of the cell and caused chromatin open regions to be upregulated. In addition, P. multocida infection actively mobilized the host immune response with the inflammatory phenotype. The findings provide valuable information for understanding the regulatory mechanisms of P. multocida-infected goat bronchial epithelial cells.

Unmanned aerial vehicles (UAVs) are considered an important component of 6G wireless technology. However, there are many challenges to the employment of UAVs, one of which is spectrum scarcity. To address this challenge, non-orthogonal multiple access (NOMA) and cognitive radio (CR) techniques are employed in UAV short-packet communication systems. In this paper, we consider a NOMA-based cognitive UAV short-packet communication system. Firstly, a mathematical expression for the effective throughput of the secondary users is derived. Then, we aim to maximize the effective throughput of the far secondary user by optimizing the sensing time, power allocation, and information bits under the constraints of the transmission power and effective decoding error probability. A joint optimization algorithm is used to solve this problem, where the bisection method and the one-dimensional linear search algorithm are used to solve the subproblem. The simulation results show that the proposed algorithm has low complexity and similar performance compared to the exhaustive method. In addition, the necessity of joint optimization is shown in the simulation results.

Thin-layer chromatography (TLC) is one of the basic analytical procedures in chemistry and allows the demonstration of various chemical principles in an educational setting. An often-overlooked aspect of TLC is the capability to quantify isolated target compounds in an unknown sample. Here, we present a suitable route to implement quantitative analysis in a lesson plan. We provide both a stand-alone software and an online webapp that allow students to obtain quantitative information from a developed TLC plate and present two suitable experiments, namely, the absorbance-based quantification of the colorant Sudan IV and the fluorescence-based quantification of rhodamine 6G, a fluorophore widely used in biotechnology. Students conduct TLC experiments following established protocols, take pictures of their TLC plates with mobile phones, and subsequently quantify the different compounds in the separate bands they observe.

Lightweight polycrystalline ceramics possess promising physical, chemical, and mechanical properties, which can be used in a variety of important structural applications. However, these ceramics with coarse-grained structures are brittle and have low fracture toughness due to their rigid covalent bonding (more often consisting of high-angle grain boundaries) that can cause catastrophic failures. Nanocrystalline ceramics with soft interface phases or disordered structures at grain boundaries have been demonstrated to enhance their mechanical properties, such as strength, toughness, and ductility, significantly. In this review, the underlying deformation mechanisms that are contributing to the enhanced mechanical properties of superhard nanocrystalline ceramics, particularly in boron carbide and silicon carbide, are elucidated using state-of-the-art transmission electron microscopy and first-principles simulations. The observations on these superhard ceramics revealed that grain boundary sliding induced amorphization can effectively accommodate local deformation, leading to an outstanding combination of mechanical properties.

As a new tumor treatment strategy, photothermal therapy (PTT) has the advantages of accuracy, ease of administration, a high efficiency and low side effects. Photothermal transduction agents (PTAs) are the key factor which play an important role in PTT. The mechanism of PTT is discussed in detail. The photothermal conversion efficiency (PCE) can be improved by increasing the light absorption and reducing the light scattering of photothermal conversion agents. Additionally, non-radiative relaxation path attenuation can also promote energy conversion to obtain a higher value in terms of PCE. The structure and photothermal characteristics of various kinds of PTAs (metal materials, carbon-based nanomaterials, two-dimensional nanomaterials, and organic materials) were compared and analyzed. This paper reviews the antitumor applications of photothermal synergistic therapies, including PTT combined with immunotherapy, chemotherapy, and photodynamic therapy. This review proposes that these PTAs promote the development of photothermal synergistic therapies and have a great potential in the application of tumor treatment.

Wall-associated kinases (WAKs) are important receptor-like proteins that play major roles in plant defense against pathogens. Fusarium head blight (FHB), one of the most widespread and devastating crop diseases, reduces wheat yield and leads to quality deterioration. Although WAK gene families have been studied in many plants, systematic research on bread wheat (Triticum aestivum) and its role in FHB resistance, in particular, is lacking. In this study, we identified and characterized 320 genes of the TaWAK family in wheat distributed across all chromosomes except 4B and divided them into three phylogenetic groups. Duplication and synteny analyses provided valuable information on the evolutionary characteristics of the TaWAK genes. The gene expression pattern analysis suggested that TaWAK genes play diverse roles in plant biological processes and that at least 30 genes may be involved in the response to Fusarium infection in wheat spikes, with most of the genes contributing to pectin- and chitin-induced defense pathways. Furthermore, 45 TaWAK genes were identified within 17 hcmQTLs that are related to wheat FHB resistance. Our findings provide potential candidate genes for improving FHB resistance and insights into the future functional analysis of TaWAK genes in wheat.

Early detection and discovery of new therapeutic targets are urgently needed to improve the breast cancer treatment outcome. Here we conducted an official clinical trial with cross-validation to corroborate human plasma Hsp90α as a novel breast cancer biomarker. Importantly, similar results were noticed in detecting early-stage breast cancer patients. Additionally, levels of plasma Hsp90α in breast cancer patients were gradually elevated as their clinical stages of regional lymph nodes advanced. In orthotopic breast cancer mouse models, administrating with recombinant Hsp90α protein increased both the primary tumor lymphatic vessel density and sentinel lymph node metastasis by 2 and 10 times, respectively. What is more, Hsp90α neutralizing antibody treatment approximately reduced 70% of lymphatic vessel density and 90% of sentinel lymph node metastasis. In the in vitro study, we demonstrated the role of extracellular Hsp90α (eHsp90α) as a pro-lymphangiogenic factor, which significantly enhanced migration and tube formation abilities of lymphatic endothelial cells (LECs). Mechanistically, eHsp90α signaled to the AKT pathway through low-density lipoprotein receptor-related protein 1 (LRP1) to upregulate the expression and secretion of CXCL8 in the lymphangiogenic process. Collectively, this study proves that plasma Hsp90α serves as an auxiliary diagnosis biomarker and eHsp90α as a molecular mediator promoting lymphangiogenesis in breast cancer.

Metal-free thermally activated delayed fluorescence (TADF) emitters have emerged as promising candidate materials for highly efficient and low-cost organic light-emitting diodes (OLEDs). Here, a novel acceptor 2-cyanopyrazine is selected for the construction of blue TADF molecules via computer-assisted molecular design. Both theoretical prediction and experimental photophysical data indicate a small S1-T1 energy gap (ΔEST) and a relative large fluorescence rate (kF) in an o-phenylene-bridged 2-cyanopyrazine/3,6-di-tert-butylcarbazole compound (TCzPZCN). The kF value of 3.7 × 107 s−1 observed in a TCzPZCN doped film is among the highest in the TADF emitters with a ΔEST smaller than 0.1 eV. Blue TADF emission is observed in a TCzPZCN doped film with a short TADF lifetime of 1.9 μs. The OLEDs using TCzPZCN as emitter exhibit a maximum external quantum efficiency (EQE) of 7.6% with low-efficiency roll-off. A sky-blue device containing a derivative of TCzPZCN achieves an improved EQE maximum of 12.2% by suppressing the non-radiative decay at T1.

For the first time, aluminum alloy was used as the main source to prepare aluminum oxide-modified carbon nitride with a melamine–cyanuric acid supramolecular complex. The introduction of amorphous aluminum oxide confers macroporosity to the skeletons of g-C3N4-AlOx. Its surface area increased to 75.5 m2g−1, about 1.5 times that of single g-C3N4. After modification, the visible light response range was expanded, especially at 450~500 nm, while the band structure could be adjusted. Compared with g-C3N4, g-C3N4-AlOx has better photocatalytic performance, the adsorption rate for the dye rhodamine B (RhB) is about 2.1 times that of g-C3N4, and the RhB removal rate is 1.2 times that of g-C3N4.

The purpose of this study was primarily to explore high school students' cognitive structures and to identify their learning difficulties on ethanoic acid through the flow map method. The subjects of this study were 30 grade 1 students from Dong Yuan Road Senior High School in Xi'an, China. The interviews were conducted a week after the students had received instruction on ethanoic acid. The interview narratives were then transcribed into flow maps. Analysis of the flow maps showed that there existed a difference between the individual students' cognitive structure on ethanoic acid, higher academic achievers constructed more enriched cognitive structures and had higher scores for cognitive structural variables than lower academic achievers. Furthermore, the results of the correlation analysis of the students' cognitive structure outcomes, academic achievement and the information processing modes revealed that there was a positive correlation between two of them to some extent; in general, the higher academic achievers tended to have higher cognitive structure outcomes and employed high-order information processing modes. Analysis of the content of the flow maps of all the participants indicated that most of the students knew the main facts about ethanoic acid, but the details were not complete, and the misconceptions were mainly related to the molecular constitution and structure of ethanoic acid as well as to the esterification reaction, while the knowledge of the physical properties and the acidity of ethanoic acid seemed to have been mastered relatively well, as for the applications of ethanoic acid, students only mentioned that it can be used as condiment.

Network bandwidth is a scarce resource in big data environments, so data locality is a fundamental problem for data-parallel frameworks such as Hadoop and Spark. This problem is exacerbated in multicore server-based clusters, where multiple tasks running on the same server compete for the server’s network bandwidth. Existing approaches solve this problem by scheduling computational tasks near the input data and considering the server’s free time, data placements, and data transfer costs. However, such approaches usually set identical values for data transfer costs, even though a multicore server’s data transfer cost increases with the number of data-remote tasks. Eventually, this hampers data-processing time, by minimizing it ineffectively. As a solution, we propose DynDL (Dynamic Data Locality), a novel data-locality-aware task-scheduling model that handles dynamic data transfer costs for multicore servers. DynDL offers greater flexibility than existing approaches by using a set of non-decreasing functions to evaluate dynamic data transfer costs. We also propose online and offline algorithms (based on DynDL) that minimize data-processing time and adaptively adjust data locality. Although DynDL is NP-complete (nondeterministic polynomial-complete), we prove that the offline algorithm runs in quadratic time and generates optimal results for DynDL’s specific uses. Using a series of simulations and real-world executions, we show that our algorithms are 30% better than algorithms that do not consider dynamic data transfer costs in terms of data-processing time. Moreover, they can adaptively adjust data localities based on the server’s free time, data placement, and network bandwidth, and schedule tens of thousands of tasks within subseconds or seconds.

The supramolecular assembly of proteins on surfaces has been investigated via the site-selective incorporation of a supramolecular moiety on proteins. To this end, fluorescent proteins have been site-selectively labeled with ferrocenes, as supramolecular guest moieties, via SNAP-tag technology. The assembly of guest-functionalized SNAP-fusion proteins on cyclodextrin- and cucurbit[7]uril-coated surfaces yielded stable monolayers. The binding of all ferrocene fusion proteins is specific as determined by surface plasmon resonance. Micropatterns of the fusion proteins, on patterned cyclodextrin and cucurbituril surfaces, have been visualized using fluorescence microscopy. The SNAP-fusion proteins were also immobilized on cyclodextrin vesicles. The supramolecular SNAP-tag labeling of proteins, thus, allows for the assembly of modified proteins via supramolecular host-guest interaction on different surfaces in a controlled manner. These findings extend the toolbox of fabricating supramolecular protein patterns on surfaces taking advantage of the high labeling efficiency of the SNAP-tag with versatile supramolecular moieties.

Four lowest electronic states [Please download the PDF to view the mathematical expression] of the HeH radical are investigated by performing high-precision ab initio calculations. Potential energy curves of HeH are calculated using the multireference configuration interaction method and the basis set of aug-cc-pV6Z. Additional Rydberg basis functions and the Pople correction are included in the calculations. The spectral parameters are evaluated and compared with literature data. The spin-orbit coupling effect of [B.sup.2][PI] is taken into account by using the Breit-Pauli operator. Transition dipole moments between those four electronic states are also derived to obtain their emission spectra and radiative lifetimes. Radiative and predissociation lifetimes of several vibrational levels are also calculated, including the bound-continuum and bound-bound systems. Especially, the predissociation lifetimes are elaborated in detail. The results are in good agreement with the reported ones. Additionally, the emission spectra of bound A [Please download the PDF to view the mathematical expression], and [C.sup.2][SIGMA]+ states to continuum [X.sup.2][SIGMA]+ state are simulated at different temperatures. Key words: HeH radical, spectroscopic parameter, radiative and predissociation lifetime, emission spectra Nous avons etudie les quatre etats electroniques les plus bas [Please download the PDF to view the mathematical expression] du radical HeH a l'aide de calculs ab initio de haute precision. Nous avons calcule les courbes d'energie potentielle de la molecule de HeH a l'aide de la methode d'interaction de configurations multi-reference a contraction interne en utilisant la base aug-cc-pV6Z. Pour ameliorer la precision, nous avons integre aux calculs d'autres bases de Rydberg et applique la correction de Pople. Nous avons evalue les parametres spectraux et les avons compares aux donnees de la litterature. Par ailleurs, nous avons pris en compte l'efet des couplages spin-orbite de [B.sup.2][PI] en utilisant l'operateur Breit-Pauli. Nous avons egalement derive les moments dipolaires de transition entre ces quatre etats electroniques pour obtenir leur spectre d'emission et leur duree de vie radiative. De plus, nous avons calcule la duree de vie radiative et la duree de vie de predissociation de plusieurs niveaux vibrationnels, y compris les systemes de type lie-continuum et lie-lie. Plus particulierement, nous abordons en detail les durees de vie de predissociation. Les resultats concordent bien avec ceux de la litterature. De plus, nous avons realise des simulations des spectres d'emission de la transition des etats lies [Please download the PDF to view the mathematical expression] et [Please download the PDF to view the mathematical expression] a l'etat du continuum [X.sup.2][SIGMA]+ a diferentes temperatures. [Traduit par la Redaction] Mots-cles : radical HeH, parametre spectroscopique, duree de vie radiative et duree de vie de predissociation, spectres d'emission, 1 Introduction The HeH radical is one of the simplest heteronuclear diatomic molecules. Three elements (including hydrogen, helium, and lithium) and some of their isotopes were produced in the earliest [...]

We synthesized and developed 1,3-dihydro-2H-imidazo[4,5-b]phenazine-2-thione as a ratiometric chemosensor for [Hg.sup.2+] recognition in a DMSO/[H.sub.2]O (v/v = 9:1) binary solution. We rationally introduced the phenazine imidazole group as the fluorophore and the thione moiety as the recognition site to bind [Hg.sup.2+]. Interestingly, the chemosensor showed an ultrasensitive response to [Hg.sup.2+], and the lowest limit of detection was 0.167 nM. In addition, it can also separate [Hg.sup.2+] from aqueous solutions with excellent ingestion capacity, with an adsorption ratio of up to 96%. Furthermore, ion test strips based on chemosensors were fabricated for convenient and efficient detection of [Hg.sup.2+]. Key words: fluorometric, chemosensor, imidazo[4,5-b]phenazine-2-thione, ultrasensitive detection, separation, [Hg.sup.2+]. Nous avons synthetise la 1,3-dihydro-2H-imidazo[4,5-b]phenazine-2-thione afin de mettre au point un capteur chimique ratiometrique pour la reconnaissance des ions [Hg.sup.2+] dans une solution binaire de DMSO/[H.sub.2]O (v/v = 9:1). Nous avons selectionne de maniere rationnelle le groupe imidazophenazine comme fluorophore et le fragment thione comme site de reconnaissance afin qu'il se lie a l'ion [Hg.sup.2+]. Il est interessant de noter que le capteur chimique presente une reponse ultrasensible aux ions [Hg.sup.2+] et une limite inferieure de detection de 0,167 nM. De plus, il permet de separer les ions [Hg.sup.2+] de la solution aqueuse avec une excellente capacite d'ingestion, le rapport d'adsorption atteignant 96 %. En outre, nous avons fabrique des bandelettes d'analyse ioniques permettant de detecter facilement et efficacement les ions [Hg.sup.2+] a l'aide du capteur chimique. [Traduit par la Redaction] Mots-cles : fluorimetrique, capteur chimique, imidazo[4,5-b]phenazine-2-thione, detection ultrasensible, separation, [Hg.sup.2+]., Introduction Recently, ultrasensitive detection has received significant attention owing to its crucial biological, chemical, and environmental applications. (1-5) Over the past few years, numerous methods have been reported for ultrasensitive [...]

In this work, it is shown that Mo[O.sub.3-x] has a positive effect on the thermal decomposition of ammonium perchlorate based molecular perovskite [([H.sub.2]DABCO)[[NH.sub.4]([ClO.sub.4]).sub.3]] (DAP-4). Mo[O.sub.3-x] was prepared by heat treatment, and the morphology, structure, and thermal decomposition performance were characterized. The morphology and structure characterization results showed that Mo[O.sub.3-x] was an irregular layered structure material and the Mo element was mainly in the +6 chemical valence state, with a small amount of [Mo.sup.5+]. Thermal analysis results showed that the thermal decomposition peak temperature of DAP-4 was effectively reduced from 394.4 [degrees]C to 353.7 [degrees]C, 321.4 [degrees]C, and 312.5 [degrees]C in the presence of 1%, 5%, and 10% Mo[O.sub.3-x], respectively. It is particularly worth noting that the maximum heat release rate of the DAP-4/10% Mo[O.sub.3-x] mixture was increased by 4.9 times compared with pure DAP-4. Through the two classic thermal decomposition kinetic methods, Kissinger and Starink, the reliable kinetic parameters of DAP-4/Mo[O.sub.3-x] were obtained. The increase of the reaction rate constant k indicated that the maximum thermal decomposition reaction rate of DAP-4 was effectively improved. This work provided a feasible technology for using [MoO.sub.3-x] as an effective catalyst to improve the thermal performance of DAP-4. Key words: Mo[O.sub.3-x], molecular perovskite, [([H.sub.2]DABCO)[[NH.sub.4]([ClO.sub.4]).sub.3]] DAP-4, catalysis, thermal decomposition. Dans le cadre des presents travaux, nous avons demontre que le Mo[O.sub.3-x] a un effet positif sur la decomposition thermique de la perovskite moleculaire a base de perchlorate d'ammonium [([H.sub.2]DABCO)[[NH.sub.4]([ClO.sub.4]).sub.3]] (DAP4). Nous avons prepare le Mo[O.sub.3-x] par traitement thermique et nous avons caracterise sa morphologie, sa structure et sa performance de decomposition thermique. Les resultats de caracterisation morphologique et structurale ont montre que le [Mo.sub.3-x] est un materiau de structure lamellaire irreguliere et que l'element Mo se trouvait principalement dans l'etat de valence chimique +6, dont une faible proportion de [Mo.sup.5+]. Les resultats de l'analyse thermique ont montre que la temperature maximale de decomposition thermique du DAP4 etait effectivement reduite, passant de 394,4 [degrees]C a 353,7 [degrees]C, a 321,4 [degrees]C et a 312,5 [degrees]C en presence de 1 %, de 5 % et de 10 % Mo[O.sub.3-x], respectivement. Il est particulierement important de noter que le debit calorifique maximal du melange de DAP4 a 10 % de Mo[O.sub.3-x] a ete multiplie par 4,9 par rapport a celui du DAP4 pur. A l'aide des deux methodes classiques de la cinetique de decomposition thermique, celles de Kissinger et de Starink, nous avons determine de maniere fiable les parametres cinetiques du DAP4/Mo[O.sub.3-x]. L'augmentation de la constante de vitesse de reaction k indique que la vitesse maximale de la reaction de decomposition thermique du DAP4 est effectivement accrue. Ces travaux permettent de proposer une technologie realiste faisant appel au Mo[O.sub.3-x] comme catalyseur efficace pour ameliorer la performance thermique du DAP4. Mots-cles : Mo[O.sub.3-x], perovskite moleculaire, [([H.sub.2]DABCO)[[NH.sub.4]([ClO.sub.4]).sub.3]] DAP-4, catalyse, decomposition thermique., Introduction Molybdenum trioxide (Mo[O.sub.3]) is a typical transition metal oxide and has abundant reserves in nature. There are three common phase structures, namely the thermodynamically stable orthogonal phase structure ([alpha]-Mo[O.sub.3]) [...]

To further study the mechanism of coal self-heating, the reaction sequences and thermodynamic properties between sulfur-containing groups and oxygen during coal self-heating were analyzed. The benzyl mercaptan and diphenyl sulfide were selected as typical sulfur-containing structures existing in coal. Their structural parameters, frontier orbital characteristics, and thermodynamic parameters were analyzed through quantum chemistry calculation and their detailed reaction sequences with oxygen were proposed. The results indicate that the thiol structure in coal can easily react with oxygen at low temperatures and release large amounts of heat (146.70 kJ/mol) during coal self-heating, providing active free radicals and energy for subsequent chain reactions of coal spontaneous combustion. The oxidation reaction between the thioether structure and oxygen cannot occur at room temperature. With the accumulation of heat, thioether gradually becomes active and reacts with oxygen to form sulfoxide and release an enormous amount of heat (248.09 kJ/mol), which can be further oxidized to sulfone with an increase in temperature. The reaction models of thiol and thioether groups during coal self-heating were proposed, which involves eight main reaction sequences (R1~R8). It indicates that the reactions of thiol and thioether groups play crucial roles during the evolution of coal self-heating, with a slow oxidation stage at low temperatures and an accelerated oxidation stage at high temperatures. Key words: sulfur-containing groups, quantum chemistry calculation, reaction model, coal self-heating. Pour etudier plus en detail le mecanisme de combustion spontanee du charbon, nous avons analyse les sequences de reaction entre les groupes contenant du soufre et l'oxygene durant la combustion spontanee du charbon, ainsi que les proprietes thermodynamiques de ces reactions. Nous avons selectionne le benzylmercaptan et le sulfure de diphenyle comme structures typiques contenant du soufre presentes dans le charbon. Nous avons analyse, par des calculs de chimie quantique, les parametres structuraux et thermodynamiques de ces composes ainsi que les caracteristiques de leurs orbitales frontieres et nous avons propose des sequences detaillees de leur reaction avec l'oxygene. Les resultats indiquent que la structure du thiol dans le charbon peut facilement reagir avec l'oxygene a basse temperature et liberer de grandes quantites de chaleur (146,70 kJ/mol) au cours de la combustion spontanee du charbon, fournissant ainsi des radicaux libres actifs et de l'energie qui permettent a des reactions en chaine de produire ensuite dans le processus de combustion spontanee du charbon. La reaction d'oxydation entre la structure thioether et l'oxygene ne peut pas se produire a temperature ambiante. Avec l'accumulation de chaleur, le thioether devient progressivement actif et reagit avec l'oxygene pour former un sulfoxyde, liberant une enorme quantite de chaleur (248,09 kJ/mol). Ce sulfoxyde peut etre oxyde davantage en sulfone, produisant une augmentation de temperature. Nous avons propose des modeles pour les reactions des groupes thiol et thioether se produisant au cours de la combustion spontanee du charbon qui comportent huit sequences principales de reaction (R1~R8). Ces modeles indiquent que les reactions des groupes thiol et thioether jouent un role crucial au cours du processus de combustion du charbon, tant au stade d'oxydation lente a basse temperature qu'au stade d'oxydation accelere a des temperatures elevees. [Traduit par la Redaction] Mots-cles : groupes contenant du soufre, calcul de chimie quantique, modele de reaction, combustion spontanee du charbon., Introduction Coal self-heating seriously endangers coal mining, storage, and transportation. (1) Under certain conditions, the phenomenon of coal self-heating will be converted into coal self-ignition, which can cause huge safety [...]

This study explores the problem of fast estimation of soil particle content by visible-near-infrared vis-NIR) spectroscopy. Four spectral pre-processing methods were used, and it was found that the multiplicative scatter correction (MSC) preprocessing transformation can maintain the original spectral characteristics and effectively eliminate the influence of scattering, with the best effect. Compared with the spectral index (SI) established by the original spectral data, the SI established by the MSC greatly increases its correlation and sensitivity with the soil particle content. The partial least squares (PLS) and random forest (RF) models were optimized using the successive projections algorithm (SPA), and it was found that the model complexity and calculation amount were greatly reduced, and the model accuracy was improved. The reserved samples were verified, and a good prediction effect was achieved. Our results show that the combination of spectral index and successive projection algorithm can be used as an effective means for rapid prediction of soil particle content., Soil, composed of solid, liquid, and gas, plays a vital role in human life. As the global population increases and arable land decreases, our understanding of soil continues to deepen. [...]

The modified attachment energy model was applied to predict the crystal morphology of hexanitrohexaazaisowurtzitane/1,3-dinitrobenzene (HNIW/DNB) cocrystal in ethanol. A double-layer interface structure was established based on experiments. Molecular dynamics simulation was employed to investigate the interaction of flat faces and ethanol solvents. We used periodic bond chains and roughness calculations to analyze the characteristics of the HNIW/DNB cocrystal. The crystal morphology of the HNIW/DNB cocrystal is mainly composed of the (001), (010), (102), and (111) faces in vacuum. The (001) face occupies the largest area (49.54%). In ethanol, the area of the (001) face increases to 68.58%. Ethanol molecules are adsorbed on the polar face through hydrogen bonding. In the slowest growth direction, two HNIW layers and one DNB layer alternately appear. The higher molecular recognition of the (001) face of HNIW/DNB resulted in this face becoming the most important growth face. Meanwhile, we also predicted the crystal morphologies of [epsilon]-HNIW and DNB in ethanol. The prediction morphologies are in excellent agreement with the experimental shapes. These simulation results can provide guidance for the recrystallization of HNIW/DNB. Key words: hexanitrohexaazaisowurtzitane, 1,3-dinitrobenzene, crystal morphology, molecular dynamics simulation, attachment energy model. Nous avons employe le modele d'energie de fixation modifie pour predire la morphologie cristalline du cocristal de HNIW/DNB dans l'ethanol. A partir de donnees experimentales, nous avons etabli que la structure de l'interface se presentait sous forme de double couche. Nous avons effectue une simulation de dynamique moleculaire pour etudier l'interaction entre les faces planes et le solvant, soit l'ethanol. Nous avons utilise la theorie des chaines de liaisons periodiques et le calcul de rugosite pour analyser les caracteristiques du cocristal de HNIW/DNB. La morphologie cristalline du cocristal de HNIW/DNB dans le vide est principalement decrite par les faces (001), (010), (102) et (111). La face (001) constitue la majorite de la surface, soit 49,54 %. Dans l'ethanol, le pourcentage de surface de la face (001) passe a 68,58 %. Les molecules d'ethanol sont adsorbees par liaison hydrogene sur la face polaire. Dans la direction de croissance la plus lente, deux couches de HNIW et une couche de DNB se succedent en alternance. Une meilleure reconnaissance moleculaire de la face (001) du cocristal de HNIW/DNB a revele que cette face devenait la face de croissance la plus importante. Parallelement, nous avons egalement predit les morphologies cristallines du [epsilon]-HNIW et du DNB dans l'ethanol. Les morphologies predites par le modele montrent une excellente concordance avec les formes observees experimentalement. Ces resultats de simulation peuvent servir a orienter les conditions de recristallisation du HNIW/DNB. [Traduit par la Redaction] Mots-cles : hexanitrohexaazaisowurtzitane, 1,3-dinitrobenzene, morphologie cristalline, simulation de dynamique moleculaire, modele d'energie de fixation., Introduction The crystal habit depends directly on the composition of crystals and become associated more closely with the physical and chemical conditions. (1-3) The study of growth habits not only [...]

An efficient method for the synthesis of 2-substituted benzo[f]isoindole-4,9-dione derivatives from N-substituted iminodiacetates and quinones via a Cu(II)-promoted oxidation/[3 + 2] cycloaddition/aromatization tandem reaction was reported. This tandem reaction uses a wide range of N-substituted iminodiacetate derivatives that contain the chain-alkyl, cycloalkyl, and aryl group on the N-atom. Based on optimized reaction conditions, the desired product of 2-substituted benzo[f]isoindole-4,9-diones was obtained in moderate to excellent yields. Taken together, the promising results of this research would provide an especially efficient strategy to synthesize polysubstituted pyrroles from easy available starting materials and promoted by cheaper [Cu(OAc).sub.2]. Key words: tandem reaction, Cu(II)-promoted, 2-substituted benzo[f]isoindole-4,9-dione, oxidation/[3 + 2] cycloaddition/aromatization. Nous présentons une méthode efficace pour la synthèse des dérivés de benzo[f]isoindole-4,9-dione susbstitués en position 2 à partir d'iminodiacétates N-substitués et de quinones. La méthode proposée fait appel à une réaction en tandem qui consiste en une oxydation catalysée par le Cu(II) suivie d'une cycloaddition [3 + 2] et d'une aromatisation. Cette réaction en tandem admet une grande variété de dérivés d'iminodiacétate N-substitués comportant une chaîne alkyle ou un groupe cycloalkyle ou aryle sur l'atome d'azote. En conditions réactionnelles optimisées, nous avons obtenu le produit désiré, soit les benzo[f]isoindole-4,9-diones substituées en position 2, en rendements modérés à excellents. Pris dans leur ensemble, les résultats prometteurs de ces travaux pourraient constituer une stratégie particulièrement efficace pour synthétiser des pyrroles polysubstitués à partir de produits de départ facilement accessibles et de [Cu(OAc).sub.2], un catalyseur peu coûteux. [Traduit par la Rédaction] Mots-clés : réaction en tandem, catalyse par le Cu(II), benzo[f]isoindole-4,9-dione substitué en position 2, oxidation--cycloaddition [3 + 2]--aromatization., Introduction First-row transition metals have been widely used in the construction of organic molecules and have greatly enriched synthetic chemistry in recent years. (1-5) In particular, due to their lower [...]

Food without additives has been favored by consumers. However, there are many foods that contain additives but are marked as additives-free and natural foods. The purpose of this work is to detect several common additives in drinks using three-dimensional fluorescence spectroscopy (TDFS) combined with an independent component analysis (ICA) algorithm. In the experiment, the artificial sample and the real sample are analyzed to determine the components. For artificial samples, acceptable results were able to be obtained even if the components are highly correlated. For real samples, some were shown to contain more than one kind of additive that is not consistent with the label 'additive-free.' Three parameters (root mean square error of prediction [RMSEP], a similarity coefficient [p], and an R-squared estimate [[R.sup.2]]) are used to evaluate results. The results indicate that ICA works well in food additive detection. In addition, ICA can analyze the raw spectra without data preprocessing. Therefore, this work is helpful for food safety inspection., Mmassive amounts of chemical additives are added to foods to maintain or improve the color, flavor, and sweetness, as well as to extend the expiration date (1). Legislation has indicated [...]

A facile protocol for the synthesis of quinoline formaldehydes via direct oxidative C--H bonds functionalization of methyl-azaheteroarenes in the presence of [I.sub.2]--DMSO has been described. This method is metal-free and easy to operate. This reaction provided a convenient route for the preparation of a range of important quinoline formaldehydes. Key words: metal free, oxidative functionalization, methyl-azaheteroarenes, quinoline formaldehydes, iodine. Nous decrivons une methode de synthese facile pour preparer des formaldehydes derives de la quinoline par fonctionnalisation directe de methylazaheteroarenes via l'oxydation de liaisons C--H en presence d'un melange d'I2 dans le DMSO. Cette methode, simple a realiser, fonctionne sans metaux. La reaction constitue une voie d'acces pratique a une variete de formaldehydes de quinoline importants. [Traduit par la Redaction] Mots-cles : sans metaux, fonctionnalisation oxydante, methylazaheteroarenes, formaldehydes de quinoline, iode., Introduction (Hetero)aryl aldehydes ketones are integral parts of various natural products, and they are widely employed as key synthetic intermediates in pharmaceuticals and organic synthesis. (1) In particular, quinoline formaldehyde [...]

In this work, a novel sensor molecule HB1, based on a 4-(diethylamino)-2-(hydroxy)-phenyl imine functionalized naphthalimide derivative, was successfully designed and synthesized. Interestingly, the HB1 showed fluorescence identification ability for CN- in DMSO/[H.sub.2]O (8:2, v/v) solution. After addition of [CN.sup.-] into the HB1 solution, the fluorescence intensity of HB1 solution could be enhanced obviously. The anti-disturbance experiments demonstrated that other anions could not interfere in the detection of [CN.sup.-]. On the other hand, HB1 was capable of dual-channel (absorption and fluorescence) detection of [Fe.sup.3+] in DMSO solution. With the addition of various metal ions into the HB1 solution, only [Fe.sup.3+] induced the fluorescence emission of HB1 solution quenching and the colour change, and other metal ions could not interfere in the detection of [Fe.sup.3+]. The limits of detection (LODs) of HB1 for [CN.sup.-] and [Fe.sup.3+] were 6.30 X [10.sup.-8] and 3.95 X [10.sup.-8] mol/L, respectively. Importantly, the real sample experiment was carried out by detecting [CN.sup.-] in bitter almonds. Additionally, ion test strips based on HB1 were fabricated, which could act as convenient and efficient test kits for detecting [CN.sup.-] and [Fe.sup.3+]. Key words: sensor molecule, naphthalimide derivative, real samples, test kits. Dans le cadre des présents travaux, nous avons conçu et synthétisé le HB1, une nouvelle molécule sensible basée sur un dérivé de naphtalimide fonctionnalisé par la 4-(diéthylamino)-2-(hydroxy)-phénylimine. Fait intéressant, le HB1 s'est montré capable de détecter par fluorescence l'ion [CN.sup.-] en solution dans un mélange de DMSO/[H.sub.2]O(8:2, v/v). Après l'ajout d'ions [CN.sup.-] dans la solution de HB1, nous avons pu observer une augmentation visible de l'intensité de fluorescence de la solution de HB1. Les expériences d'interférences ont permis de démontrer que les autres anions ne pouvaient pas interférer avec la détection des ions [CN.sup.-]. Par ailleurs, le HB1 permet détection bimodale (absorption et fluorescence) des ions [Fe.sup.3+] en solution dans le DMSO. En ajoutant divers ions métalliques dans la solution de HB1, nous avons observé que seuls les ions [Fe.sup.3+] induisaient l'émission de fluorescence de la solution de HB1, l'extinction de fluorescence et le changement de couleur, et que les autres ions métalliques ne pouvaient pas interférer avec la détection des ions [Fe.sup.3+]. Les limites de détection (LD) des ions [CN.sup.-] et [Fe.sup.3+] par le HB1 étaient de 6,30 X [10.sup.-8] mol/L et de 3,95 X [10.sup.-8] mol/L, respectivement. Fait important, nous avons mené les expériences de détection des ions [CN.sup.-] sur des échantillons réels d'amandes amères. Parallèlement, des bandelettes d'analyse d'ions à base de HB1 ont été fabriquées et pourraient trouver une application dans des trousses d'analyse pratiques et efficaces pour la détection des ions CN-et [Fe.sup.3+]. [Traduit par la Rédaction] Mots-clés : molécule sensible, dérivés de naphtalimide, échantillons réels, trousses d'analyse., Introduction In the field of supramolecular chemistry, the study of cyanide anion ([CN.sup.-]) sensors has been a topic of much interest. (1-3) The cyanide anion is a highly toxic substance, [...]

A novel, simple, and low-cost spray painting technique has been developed for the fabrication of microfluidic paper-based devices. The devices that we developed utilize aerosol spray paint to build hydrophobic barriers and employ a hole puncher to obtain paper-based patterned layers and paper dots without using any specialized instruments (e.g., without a laser cutter). The entire manufacturing process is extremely simple, inexpensive, and rapid, which means that it can be applied broadly. Furthermore, the application of the device to iron detection was demonstrated. A linear relationship between the colour value and the iron concentration was observed from 0 to 0.02 g/L. The developed microfluidic paper-based device for iron detection exhibited a low detection limit (0.00090 g/L), good selectivity, and acceptable recovery. Key words: microfluidic paper-based device, spray painting, colorimetry, iron. Nous avons mis au point une nouvelle technique de pulverisation de peinture simple et peu couteuse pour fabriquer des dispositifs microfluidiques a base de papier. A l'aide ces dispositifs, nous avons employe de la peinture en aerosol pour fabriquer des barrieres hydrophobes et, au moyen d'un poincon, nous avons pu obtenir des couches a motifs en papier et des rondelles de papier sans avoir recours a des instruments specialises (p. ex., sans dispositif de coupe au laser). Tout le processus de fabrication est extremement simple, rapide et peu couteux, ce qui permet son application a grande echelle. Par ailleurs, nous avons demontre l'application du dispositif a la detection du fer. Nous avons observe une relation lineaire entre l'intensite de la couleur et la concentration du fer dans l'intervalle de 0 a 0,02 g/L. Le dispositif microfluidique a base de papier employe applique a la detection du fer a montre une faible limite de detection (0,00090 g/L), une bonne selectivite et un taux de recuperation acceptable. [Traduit par la Redaction] Mots-cles : dispositif microfluidique a papier, peinture en aerosol, colorimetrie, fer., Introduction Microfluidic paper-based analytical devices ([mu]PADs) have emerged at the intersection of engineering, physics, chemistry, biochemistry, nanotechnology, and biotechnology, with practical applications in the design of systems in which low [...]