Search

Experimentally observed magnetic properties are usually statistically averaged from bulk materials and information associated with the local chemical environment cannot be specified. Against this backdrop, we propose a theoretical strategy to provide an in-depth understanding of the multi-role for metrics that may contribute to the apparent magnetic moment of iron borides. In particular, we demonstrate this strategy through systematic manipulation of the iron/boron stoichiometry of six prototype iron borides to tune their associated local structural and electronic environment to further modulate the resultant magnetic moment. The local coordinative structures of the six iron borides were resolved utilizing bond valence analysis by taking the different coordination shells into account. Furthermore, the local electronic properties of each Fe atom in these iron borides, such as charge transfer, electronic distribution, bonding feature and orbital energy level, were carefully analyzed by Bader analysis, density of states analysis and Crystal Orbital Hamilton Population analysis. From the combination of analyses of both the coordinative and electronic properties of the prototype iron borides, a linear relationship between the local magnetic moment and the bond valence as well as the average energy of the Fe 3d orbitals has been confirmed.

Spin polarized density functional theory computations were performed to elucidate electronic effects based on first-row transition metal doped Fe(100) and Fe5C2(100) surfaces for CO dissociation. Both Mn and Cr doped Fe(100) and Fe5C2(100) surfaces can enhance the dissociation of CO, while the Co, Ni and Cu doped ones are unfavorable for the dissociation of CO. Besides the BEP relationship, a linear relationship between activation energy and the electronegativity of the dopant atom is established. It can be deduced that the metals with lower electronegativity are favorable for the activation of CO. The reason has been analyzed by density of states and crystal orbital Hamilton population. The metals with lower electronegativity relative to Fe could donate electrons to doped sites and then activate CO with a more delocalized O 2p orbital. The electronic effects revealed herein are helpful for the understanding of the CO activation process and for the design of catalysts with desired activity.

To understand the mechanisms of CO activation and conversion on noble metal surfaces, direct dissociation, H-assisted activation and successive hydrogenation of CO to methanol have been computed on flat Ir(111) and Ir(100), corrugated Ir(110) and Ir(210) and stepped Ir(311) and Ir(221) surfaces. On these surfaces, CO strongly prefers top adsorption sites and has much stronger adsorption than at high coordination sites. The CO direct dissociation barrier is higher than the CO desorption energy and the reaction is very endothermic, and thus not accessible, while H-assisted CO activation is more preferred kinetically. On the H-assisted pathway, the minimum energy path is CO* → HCO* → HCOH* → HC* + OH* on the Ir(111) and Ir(100) surfaces, CO* → HCO* → HCOH* → H2COH* → H2C* + OH* on the Ir(110), Ir(210) and Ir(311) surfaces and CO* → HCO* → H2CO* → H2COH* → H2C* + OH* on the Ir(221) surface, respectively. Interestingly, methanol formation has close effective barriers with the respective C–O dissociation of the H-assisted pathway, indicating that CO can not only be hydrogenated to methanol but also form via H-assisted dissociation on the Ir surfaces. The adsorptions of surface intermediates on high index surfaces are not always stronger than those on low index surfaces, indicating that the high index surfaces should not be always blocked by surface intermediates. The behaviors of CO in adsorption, dissociation and activation on Ir surfaces are compared with those on low and high index surfaces of Fe, Co, Ni and Ru metals.

BACKGROUND: The role of purinergic receptor P2X3 in pathological bladder dysfunction and chronic pelvic pain remains unclear. We aim to investigate the effect of P2X3 on bladder function in interstitial cystitis (IC) through the IC rat model induced by cyclophosphamide (CYP). METHODS: A total of 120 female Sprague-Dawley (SD) rats were randomly divided into 6 groups: control, CYP-4h, CYP-48h, CYP-10d, CYP-30d, and CYP-45d groups. The control group was injected with normal saline. The rats in the CYP-4h and CYP-48h groups were given a single high dose. The rats in the CYP-10d, CYP-30d, and CYP-45d groups were given a low dose of CYP repeatedly every three days. Bladder voiding function was measured using urodynamic techniques to observe the effect of the P2X3 receptor on bladder function in CYP-induced IC. RESULTS: The rats in the CYP-4h group showed significant overactivity of the bladder compared with the control group, the bladder voiding interval was shortened (P

BackgroundRenal cell carcinoma (RCC) is a disease of genomic alterations, of which the complete panorama helps in facilitating molecular-guided therapy. Germline mutation profiles and associated somatic and clinical characteristics remains unexplored in Chinese RCC patients.MethodsWe retrospectively profiled the germline and somatic mutations of 322 unselected RCC patients using a panel consisting of 808 cancer-related genes. We categorized patients into three groups based on germline mutation status and compared the somatic mutation spectrum among different groups.ResultsApproximately one out of ten (9.9%) RCC patients were identified to carry pathogenic/likely pathogenic (P/LP) germline variants (PGVs), of which 3.7% were variants in syndromic RCC-associated genes and 6.2% were other cancer-predisposition genes. The most common PGV was found in VHL (2.2%), followed by FH, TSC2, ATM, BRCA1, NBN, and BLM (0.6% each). Young patients (≤46 years) were more likely to harbor PGVs. Variants in syndromic RCC-associated genes were predominant identified in young patients, while variants in other cancer-predisposition genes were found in patients >46 years more frequently. Furthermore, 39.3% (11/28) of patients carrying PGVs were detected to have somatic “second hit” events. Germline and somatic sequencing, including microsatellite instability (MSI) status analysis, provided potentially actionable therapeutic targets in 17.1% of patients in the whole cohort.ConclusionsOur results revealed that approximately 10% of RCC patients carried clinically significant germline mutations. Current guidelines recommendation for genetic testing seemed not sensitive enough to identify patients with hereditary RCC susceptibility. It is rational to promote genetic testing in RCC population.

The abnormal expression of RNA binding proteins (RBPs) in tumors can regulate the functions of immune genes and affect immune microenvironment. The characterization of immune infiltration and its regulatory mechanism from the perspective of RBPs and RBP-regulated immune genes in high-grade gliomas were comprehensively studied by bioinformatics. Prognosis-related RBPs and associated immune genes were obtained from the cancer genome atlas database (TCGA). By clustering RBPs, the potential relationship between the different clusters of RBPs expression and immune infiltration was explored. Immune-related RBP constructs immunosuppressive microenvironment in glioma by regulating immune genes and immune-related genes. Immunosuppression was the predominant type of phenotype with poor prognosis, while immunoinflammation was the predominant type of immunoinflammatory phenotype with good prognosis. RBP can construct immunosuppressive microenvironment by regulating immunosuppressive cells and stromal activation-related factors through directly and indirectly ways. Stromal activation plays a bridging role in tumor immunosuppressive regulation. The immunophenotyp depends on different enrichment states of immune-related RBP, which can change dynamically with the change of tumor pathological grade and affect the prognosis of patients.Our study suggests glioma related RBPs can potentially establish an immunosuppressive microenvironment by regulating immune genes and immune-related genes, which can be directly affected by RBPs clusters with distinct prognosis.

Cellular redox is intricately linked to energy production and normal cell function. Although the redox state of mitochondria and cytosol are connected by shuttle mechanisms, the redox state of mitochondria may differ from redox in the cytosol in response to stress. However, detecting these differences in functioning tissue is difficult. Here, we employed (13)C magnetic resonance spectroscopy (MRS) and co-polarized [1-(13)C]pyruvate and [1,3-(13)C(2)]acetoacetate ([1,3-(13)C(2)]AcAc) to monitor production of hyperpolarized (HP) lactate and β-hydroxybutyrate as indicators of cytosolic and mitochondrial redox, respectively. Isolated rat hearts were examined under normoxic conditions, during low-flow ischemia, and after pretreatment with either aminooxyacetate (AOA) or rotenone. All interventions were associated with an increase in [Pi]/[ATP] measured by (31)P NMR. In well-oxygenated untreated hearts, rapid conversion of HP [1-(13)C]pyruvate to [1-(13)C]lactate and [1,3-(13)C(2)]AcAc to [1,3-(13)C(2)]β-hydroxybutyrate ([1,3-(13)C(2)]β-HB) was readily detected. A significant increase in HP [1,3-(13)C(2)]β-HB but not [1-(13)C]lactate was observed in rotenone-treated and ischemic hearts, consistent with an increase in mitochondrial NADH but not cytosolic NADH. AOA treatments did not alter the productions of HP [1-(13)C]lactate or [1,3-(13)C(2)]β-HB. This study demonstrates that biomarkers of mitochondrial and cytosolic redox may be detected simultaneously in functioning tissue using co-polarized [1-(13)C]pyruvate and [1,3-(13)C(2)]AcAc and (13)C MRS, and that changes in mitochondrial redox may precede changes in cytosolic redox.

The natural product citral has previously been demonstrated to possess antifungal activity against Magnaporthe oryzae. The purpose of this study was to screen and annotate genes that were differentially expressed (DEGs) in M. oryzae after treatment with citral using RNA sequencing (RNA-seq). Thereafter, samples were reprepared for quantitative real-time PCR (RT-qPCR) analysis verification of RNA-seq data. The results showed that 649 DEGs in M. oryzae were significantly affected after treatment with citral (100 μg/mL) for 24 h. Kyoto Encyclopedia of Genes and Genomes (KEGG) and a gene ontology (GO) analysis showed that DEGs were mainly enriched in amino sugar and nucleotide sugar metabolic pathways, including the chitin synthesis pathway and UDP sugar synthesis pathway. The results of the RT-qPCR analysis also showed that the chitin present in M. oryzae might be degraded to chitosan, chitobiose, N-acetyl-D-glucosamine, and β-D-fructose-6-phosphate following treatment with citral. Chitin degradation was indicated by damaged cell-wall integrity. Moreover, the UDP glucose synthesis pathway was involved in glycolysis and gluconeogenesis, providing precursors for the synthesis of polysaccharides. Galactose-1-phosphate uridylyltransferase, which is involved in the regulation of UDP-α-D-galactose and α-D-galactose-1-phosphate, was downregulated. This would result in the inhibition of UDP glucose (UDP-Glc) synthesis, a reduction in cell-wall glucan content, and the destruction of cell-wall integrity.

For the aromatization of olefins (in Fischer–Tropsch synthetic oil), especially for the fluidized bed reaction with steam as the fluidized medium, improving the catalytic and hydrothermal stabilities of ZSM-5 catalysts is a research focus because of both fundamental research interests and potential commercial applications. In this work, sequential alkali treatment and phosphorus modification were carried out for ZSM-5 samples. The results obtained from characterization and reaction evaluation show that the introduction of mesopores facilitates the dispersion of phosphorus species into the pores and improves the reaction stability for 1-octene aromatization. After the hydrothermal treatment, the P-0.5A-Z5-ST sample treated with an appropriate concentration of alkali retains the most acid sites and shows the highest aromatic selectivity (22.5%) at TOS = 660 min. Therefore, a moderate distribution of mesopores in a zeolite plays an important role in the diffusions of reactants and products, as well as in the distribution of phosphorus species.

The in situ formation and removal of coke is a critical problem in heterogeneous catalysis, but its mechanism is not well understood. This work investigates the mechanism of carbon deposition and hydrogenation on an Fe cluster under high-temperature conditions with the density functional tight-binding (DFTB) based nanoreactor molecular dynamics (NMD) method. Our study shows that successive formation of carbon chains, rings, and fused rings occurred during the carbon deposition on Fe clusters. Hydrogenation of activated carbon happens through direct C-H coupling, while the hydrogenation of graphitic carbon involves hydrogenation of the edge carbon, ring-opening reaction, and dealkylation reaction. The main function of the Fe catalyst is to provide the active sites for H2 dissociation and dissociated H spillover, while its activity toward C-C bond breaking is limited. These results highlight the role of the DFTB-NMD method as an effective tool to investigate reaction mechanisms under operating conditions in heterogeneous catalysis.

Background There have been debates on the necessity of fibular osteotomy (FO) in supramalleolar osteotomy (SMOT) for the treatment of varus ankle osteoarthritis. The purpose of the current study was to compare the clinical and radiological outcomes between SMOT with and without FO in the treatment of varus ankle osteoarthritis. Methods The SMOT group included 39 patients, and the SMOT with FO group included 24 patients. The basic information reached no significant difference between groups. The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Ankle Osteoarthritis Scale (AOS), modified Takakura stage and range of motion (ROM) were used for the functional evaluation. The radiologic parameters were assessed at the last follow-up to compare the degree of talar reduction between the two groups. Results Both groups achieved significant improvements in AOFAS scores, modified Takakura stage, as well as AOS pain and functional scores (P P = 0.022). In both groups, all of the radiological parameters were significantly improved (P P P P = 0.001). The medial displacement of the talus (MDT) was better reduced in the SMOT with FO group (P = 0.006). Conclusion SMOT is a promising procedure for functional improvement and malalignment correction in varus ankle osteoarthritis but reduces ankle range of motion. If SMOT is combined with FO, talar tilt and medial displacement will be better reduced.

The TCA cycle is a central metabolic pathway for energy production and biosynthesis. A major control point of metabolic flux through the cycle is the decarboxylation of 2-ketoglutarate by the TCA cycle enzyme 2-ketoglutarate dehydrogenase (2-KGDH). In this project, we developed (13)C labeled 2-ketoglutarate derivatives to monitor 2-KGDH activity in vivo. (13)C NMR analysis of liver extracts revealed that uniformly (13)C labeled 2-ketogutarate, in its cell permeable ester form, was rapidly taken up and hydrolyzed in liver and underwent extensive metabolism to produce labeled glutamate, succinate, lactate and other metabolites. Diethyl [1,2-(13)C(2)]-2-ketoglutarate was successfully polarized by dynamic nuclear polarization and within seconds after injection into rats, the probe produced hyperpolarized [(13)C]bicarbonate in the liver reflecting flux through the TCA cycle. These experiments demonstrate that this tracer offers the possibility of directly monitoring flux through 2-KGDH in vivo.

Background: Autologous osteochondral transplantation (AOT) is one of the most effective treatments for osteochondral lesions of the talus (OLTs). Normally, medial malleolar osteotomy is used to expose posteromedial lesions. However, medial malleolar osteotomy causes additional ankle injuries and a risk of persistent pain in the ankle joint. The purpose of the current study was to evaluate a new medial malleolar triplane osteotomy method and the functional outcomes of AOT from a non-weight-bearing area of the talus for OLTs.Methods: Twenty-three patients (23 ankles), including 14 males and 9 females, received AOT with triplane osteotomy of the medial malleolus for symptomatic OLTs between September 2015 and December 2017. The mean age was 35.6 years. The mean size of the lesion area was 141.5 mm2. The visual analog scale (VAS) for pain during walking and the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score were used for the pre- and postoperative evaluations. In addition, the incorporation of the grafts was assessed by computed tomography (CT).Results: All patients had a minimum follow-up of 22 months, with an average of 37.1 months. The mean time from osteotomy to full weight-bearing activity was 8.1±2.3 weeks (range, 5-12 weeks). The VAS score improved from 4.34 preoperatively to 0.53 postoperatively (P Conclusions: AOT combined with medial malleolus triplane osteotomy is a viable option for OLTs. Patients could perform weight-bearing exercise and return to sport as early as possible, with few complications at the osteotomy site and donor site.

For the hydroformylation of alkenes, developing ligand-free heterogeneous catalysts is a research focus because of both fundamental research interests and potential commercial applications. However...

Because of the structural complexity and inhomogeneity, the effect of the coordination environment on the catalytic properties is underexplored in heterogeneous catalytic systems. To address this c...

We report the structure of weak Lewis acid sites from silanol nests in high-silica zeolite Beta obtained by dealumination. Hydrogen bond interactions in silanol nests resulted in more electropositive hydrogens as Lewis acid sites compared with isolated silanols. The structure of the Lewis acid sites was confirmed using various characterization methods, such as NMR and IR, and DFT calculations. The amount of silanol nests, and the content and strength of the Lewis acid sites, gradually changed with the calcination temperature of high-silica zeolite Si-Beta. Double-bond migration of n-butene can be catalyzed by weak Lewis acid sites through σ species as intermediates, which was completely different from the Bronsted acid sites, as measured using in situ DRIFTS. The strengths and positions of Lewis acid sites on zeolite Si-Beta afforded reactant conversion and product selectivity in the isomerization of n-butene.

Background The goal of this study is to evaluate the safety and efficacy of a novel catheter for right radial artery approach cerebral angiography. Methods Patients from the Neurology Department of The Second Affiliated Hospital of Guangxi Traditional Chinese Medical University who underwent diagnostic cerebral angiography of either the left vertebral artery dominant type or balanced type were enrolled in this study. Results A total of 167 patients were treated between February 2016 and December 2017, of whom 44 were excluded based on study exclusion criteria and 123 were enrolled in the present analysis. Bilateral subclavian artery catheterization and bilateral common carotid artery catheterization were conducted successfully in all 123 patients. The success rate of selective catheterization of the left vertebral artery was 87.8% (108/123). The success rate of selective catheterization of the right vertebral artery using the novel catheter was 89.0% (73/82). The average fluoroscopy time was 6.5 ± 3.4 min, the average operation duration was 47 ± 3.7 (range 50–90) min, and the average dosage of contrast agent was 112.3 ± 8.1 mL. One patient exhibited an absence of pulse in the punctual radial artery after the removal of the arterial compression band, but there was no evidence of ischemia of the distal hand. One patient who was undergoing dual anti-platelet drug treatment suffered from bleeding at the puncture point when deflated for 2 hr after operation; this patient was re-pressurized and re-timed. Conclusions This novel catheter improved the success rate of selective left vertebral artery catheterization, and allowed for simplification of the relevant surgical steps. The controllability of this novel catheter was satisfactory, and its associated surgical risk was found to be low.

Objectives To systematically evaluate the effects of matrix metalloproteinase-3 (MMP3) and tissue inhibitor of metalloproteinase-2 (TIMP2) on chronic Achilles tendinopathy (AT) susceptibility. Chronic AT is one of the most prevalent and severe injuries in athletes. Early studies suggested that tendon extracellular matrix (ECM) may be involved in the pathogenesis of chronic AT. MMP3 is an important member of the MMP family and is important to ECM integrity. In addition, tissue inhibitor of metalloproteinase-2 (TIMP2) can indirectly limit the activity of MMP3 activity. Design Case-control genetic association study. Methods A total of 1084 chronic AT patients and 2188 controls with Chinese Han ancestry were recruited. Twenty-one SNPs, 4 mapped to MMP3 and 17 mapped to TIMP2, were selected and genotyped. Genetic association analyses and eQTL analyses were performed. In addition, we also examined the potential effects of epistasis using a case-only study design. Results Two SNPs, rs679620 (OR = 0.82, P = 0.0006, MMP3) and rs4789932 (OR = 1.2, P = 0.0002, TIMP2) were identified to be significantly associated with chronic AT risk. No significant results were obtained from epistasis analyses. SNP rs4789932 was identified to be strongly associated with the gene expression level of TIMP2 in two types of human tissues: atrial appendage (P = 0.0003) and tibial artery (P = 0.0009). Conclusions We have identified genetic polymorphisms in MMP3 and TIMP2 to be significantly associated with chronic AT risk. Further eQTL analyses indicated that SNP rs4789932 of TIMP2 was related to the gene expression levels of TIMP2. These results suggest important roles for MMP3 and TIMP2 in the pathophysiology of chronic AT.

Experimentally, surface carbon hydrogenation on metallic iron forms CH4, ethylene/ethane, and propene/propane, while previous density functional theory studies showed that these reactions are highly endothermic. This disagreement can be attributed to the shortcoming of low coverage of surface carbon atoms and the underestimated role of surface hydrogen. On a p(4 × 4) Fe(110) surface with 0.25 ML carbon coverage (4 C atoms) and other free sites filled with H atoms, we studied surface C hydrogenation with spectators and found that the formation of CH4, ethylene/ethane, and propene/propane becomes exothermic. Coupling of CH + CH and CH3C + CH to acetylene and propylene is favored thermodynamically. Next, CHCH and CH3CCH can be hydrogenated into CH2CH and CH3CHCH, and the subsequent hydrogenation of CH2CH and CH3CHCH determines the formation and selectivity of alkenes and alkanes. The most important surface species is carbide HC for chain initiation or CH3C (RC for higher homolog) for chain propagation. This ...

A single longitudinal mode (SLM) fiber laser with a ring cavity based on Sagnac interferometer (SI) for temperature sensing in the 2-μm band is proposed and demonstrated. The simulation and experimental results show that the transmission spectrum of the SI filter is sensitive to temperature change. Based on this distinguishing feature, the correlation between the laser wavelength drift and temperature variation can be established. Experimental results show that the proposed laser operates stably at the resonant wavelength of 1988.21 nm and the optical signal-to-noise ratio is approximately 55 dB at ambient temperature. Through continuous measurement for 100 min, the fluctuation of the output laser power is lower than 0.74 dB, and the resonant wavelength shift is less than the minimum resolution of the spectrometer of 0.05 nm. This indicates that it has good stability for a certain period of time. At the same time, the laser operates stably in SLM state. A temperature sensitivity of 2.09 nm/°C is obtained in experiment. Notably, the proposed fiber laser sensor possesses the merits including high sensitivity, low cost and simple structure, which are beneficial to its practical application.

The design of cheap, non-toxic, and earth-abundant transition metal catalysts for selective hydrogenation of alkynes remains a challenge in both industry and academia. Here, we report a new atomically dispersed copper (Cu) catalyst supported on a defective nanodiamond-graphene (ND@G), which exhibits excellent catalytic performance for the selective conversion of acetylene to ethylene, i.e., with high conversion (95%), high selectivity (98%), and good stability (for more than 60 h). The unique structural feature of the Cu atoms anchored over graphene through Cu-C bonds ensures the effective activation of acetylene and easy desorption of ethylene, which is the key for the outstanding activity and selectivity of the catalyst., It is highly desired to explore cheap, non-toxic transition metals catalysts for semihydrogenation of acetylene. Here, isolated Cu atoms anchored onto a defective nanodiamond-graphene support exhibit robust catalytic performance in acetylene semihydrogenation in comparison with supported Cu clusters.

In this work, the application of organic phase chemical vapour generation (CVG)-atomic fluorescence spectrometry (AFS) was extended, firstly investigating the feasibility and analytical performance...

Effects of a novel carbon/phenolic (CF/PR) ablator filled with acidified graphitic carbon nitride (ag-C3N4) on ablative resistance were evaluated. Ablative properties of CF/PR composites were significantly enhanced by 69.23% with incorporating 0.2 wt% ag-C3N4, ascribing to the formation of the dense carbon layer over the fibers, increased graphitization degree and more pyrolysis gases. Molecular dynamics simulations of ag-C3N4 inside the matrix confirm the origins of improved ablation resistance arising from the fact that ag-C3N4 alters the breaking patterns and spatial distribution of the polymer fragments, and reduces the graphitic growth temperature by 400 K. And the decomposition of ag-C3N4 and phenolic at the fiber-matrix interface collides the fibers' surfaces to undermine the structural integrity, which induces the phase transformation from short-range to long-range order of the matrix carbon because of the templating effect (transverse) and the interlayer π-π stacking (longitudinal) of the fibers at extremely high temperature.

Conversion of straight-chain paraffins into aromatics is particularly attractive but extremely challenging in the oil refining industry. Constructing the Pt-supported catalysts with high aromatic selectivity is vital. Here, we report a strategy to use Fe-modified KL zeolites to improve the Pt atom utilization efficiency and anchor them inside KL zeolite channels via atomic-layer deposition technique. A combination of highly dispersed single-atom Pt and electron-rich Pt clusters is fabricated on the KL zeolite through the creation of proper nucleation sites. The resulted catalyst (PtFe-1/KL) exhibits excellent performance for the n-heptane aromatization (90.1% aromatic selectivity) with an apparent activation energy of 131 kJ/mol and much enhanced stability at a relatively lower temperature (420 °C). Experimental analysis and density functional theory calculation demonstrate that the single-atom Pt might play a key role in the initial dehydrogenation of n-heptane to 1-heptene, and the superior stable Pt clusters encapsulated inside Fe-decorated KL zeolite channels accelerate the 1-heptene dehydrocyclization to aromatics. The synergetic interaction between single-atom Pt and Pt clusters enables the PtFe-1/KL catalyst to be one of the most effective n-heptane aromatization catalysts reported to date.

In the information age, with the rapid emergence of multimedia computers, smart phones and various Web-based RIA applications and AR and VR technologies, the information and intelligence of the education and teaching environment has continuously enhanced. The innovation of teacher training mode and the development of teacher professionalization should be achieved by continuously improving the teacher's knowledge structure and promoting the integration of technology and teaching. To study how to construct and continuously improve the new teacher knowledge structure system integrating information technology, it will become the basic part of the innovative teacher-training model and the professional development of teachers in the new era. The college civil engineering professional education has been developing with the development of the national social economy; the demand for talents has continuously increased. In addition, the innovation of civil engineering professional teaching is in urgent need of development. It is necessary to improve the quality of the teaching team. It is imperative to study the TPACK level of civil engineering teachers. Based on this, this paper builds a dedicated test scale and retains 34 items after screening. 180 data results were obtained, through the collection of questionnaires. Then we use SPSS statistical analysis software to conduct project analysis on the test results to verify the relevance and reliability of the test items in the test scale. Then, we determine the structural validity of the test scale by factor analysis of the test results. Finally, we analyzed the factors affecting the TPACK context based on the resulting data. The results show that the national policy school environment is a macro factor that affects TPACK, and the teacher's self-efficacy is a micro factor. Based on this, we have proposed different development plans from different angles.

The structure–activity relationship is crucial in catalytic performance and material design but still largely obscure due to the complexity of heterogeneous catalytic systems. CO activation occurs widely in Fischer–Tropsch reactions and pyrometallurgy, and it is a key to understanding carburization. Here, we investigate the structure–activity relationship in Fe nanoparticles by reactive molecular dynamics simulations. We focus on two activities, the adsorption and dissociation of CO, and four structural characteristics, morphologies, sizes, defects, and heteroatoms. The results show that CO adsorption and dissociation varies with the change of nanoparticles. Line dislocation and vacancies can strikingly boost CO dissociation, suggesting an effective way to tune the CO dissociation rate. Further analysis shows that the Eley–Rideal mechanism possibly works in the early periods, followed by the Langmuir–Hinshelwood mechanism in the later periods for CO2 formation. Our results shed light on the mechanism and possible optimization of the carburization of iron.

Iron sulfides have emerged as a fascinating class of materials in electromagnetics and catalysis areas, which however are challenging in first-principles modeling because of the strongly-correlated interactions between Fe 3d and S 3p electrons. Here, we assess the performances of 14 density functionals on the structural, electronic, and magnetic properties of five iron sulfides. The PBE + U with Ueff = 2.0 eV has the overall best performance. After evaluating functionals and obtaining reliable properties, our final goal is from predicting to correlating in order to do high throughput screening for the systems since the complex structures and phases of iron sulfides, to put it in another way, to hunting a reliable descriptor for predicting their properties. In the work, we demonstrate that the crystal orbital Hamilton population (COHP) and Bader charge of Fe atoms presents a good correlation with the empirical bond valence. Our results open a new avenue to effectively investigate phases and properties for various structures of iron sulfides. Indeed, the correlations between COHP/Bader charge and bond valence can be extended to other systems.

The surface energies and the morphologies of three iron oxides (α-Fe2O3, Fe3O4, and FeO) are systematically investigated by Density Functional Theory (DFT) employing PBE and PBE+U methods. The surface energies are computed under various O chemical potential which is directly related to atmosphere condition. Compared with available experimental observations, PBE provides reasonable prediction on surface stability of all three oxides while the results of PBE+U are not well consistent with experiments for Fe2O3. Based on the Wulff construction and calculated surface energies, the micro-crystal morphologies of three iron oxides are predicted at various oxygen chemical potential. Subsequently, on basis of the data of surface energies, the effect of surface free energies on phase equilibrium of iron oxides nanoparticles are investigated. These results suggest that particle sizes of nanometer have a significant influence on the thermodynamic equilibrium shifting due to their large surfaces energies contributions. This principle can guide people control the phase transition of iron oxides by adjusting surface energies contributions by changing the sizes of particles.

An extremely large displacement of the indium site in In–S6 octahedra in LnOInS2 (Ln = La, Ce, and Pr) was found in synchrotron X-ray diffraction. LaOInS2 with off-center indium in In–S6 octahedra exhibited a wider optical band gap than CeOInS2 and PrOInS2 with on-center indium. Therefore, the electronic structure of LnOInS2 is governed by the indium site with an extremely large displacement. All LnOInS2 produced H2 gas under visible light irradiation in the presence of sacrificial electron donors.

This work extended the application of non-aqueous phase hydride generation (HG)-atomic fluorescence spectrometry (AFS), and carried out the investigation of organic media conditions and surfactant sensitization effect for the determination of arsenic. It was found that the surfactant Triton X-114 had a good sensitization effect on the determination of arsenic in octanol media, and the sensitization factor was 3.6. Compared with the traditional HG-AFS, the analytical performance of the new system for the determination of arsenic was improved. Under the optimal conditions, the limit of detection (LOD) was 0.08 μg/L.

The properties from both bulk phases (magnetism and thermal stability) and surface (composition, orientation, and stability) of iron silicide model compounds were evaluated by a theoretical study w...

This study was designed to determine the effects of deuteration in pyruvate on exchange reactions in alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and flux through pyruvate dehydrogenase (PDH). Although deuteration of a 13C enriched substrate is commonly used to increase the lifetime of a probe for hyperpolarization experiments, the potential impact of kinetic isotope effects on such substitutions has not been studied in detail. Metabolism of deuterated pyruvate was investigated in isolated rat hearts. Hearts were perfused with a 1:1 mixture of [U-13C3]pyruvate and [2-13C1]pyruvate or a 1:1 mixture of [U-13C3]pyruvate plus [2-13C1, U-2H3]pyruvate for 30 min before being freeze clamped. Another set of hearts received [2-13C1, U-2H3]pyruvate and was freeze-clamped at 3 min or 6 min. Tissue extracts were analyzed by 1H and 13C{1H} NMR spectroscopy. The chemical shift isotope effect of 2H was monitored in the 13C NMR spectra of the C2 resonance of lactate and alanine plus the C5 of glutamate. There was little kinetic isotope effect of 2H in pyruvate on flux through PDH, LDH or ALT as detected by the distribution of 13C, but the distribution of 2H differed markedly between alanine and lactate. At steady-state, alanine was a mixture of deuterated species, while lactate was largely perdeuterated. Consistent with results at steady-state, hearts freeze-clamped at 3 min or 6 min showed rapid removal of deuterium in alanine but not in lactate. Metabolism of hyperpolarized [1-13C1]pyruvate was compared to [1-13C1,U-2H3]pyruvate in isolated hearts. Consistent with the results from tissue extracts, there was little effect of deuteration on the kinetics of appearance of lactate, alanine or bicarbonate, but there was a small, time-dependent upfield chemical shift in the HP[1-13C1]alanine signal reflecting exchange of methyl deuterons with water protons. Together, these results demonstrate that (1) the kinetics of pyruvate metabolism in hearts detected by 13C NMR are not affected by replacement of the pyruvate methyl protons with deuterons and (2) that the loss of deuterium from the methyl position occurs rapidly during the conversion of pyruvate to alanine. The majority of the deuterium atoms are lost on the time-scale of a hyperpolarization experiment.

In recent years, with the rapid development of economy and the acceleration of urbanization process, building energy consumption has become an urgent problem to be solved. Its total energy consumption shows a trend of sustained growth, and the growth rate is faster and faster, so the requirements of building energy efficiency detection technology are higher and higher. Aiming at the problems of time-consuming and difficult detection of traditional detection methods, this paper introduces infrared image processing technology and proposes an energy-saving detection method for buildings based on image processing. The air tightness and heat transfer coefficient are studied respectively. Firstly, the feasibility of infrared method to detect air tightness is theoretically analyzed, and the corresponding technical scheme and detection process are given. Secondly, the infrared image is grayed and filtered to eliminate the influence of thermal defect area on the calculation of heat transfer coefficient after eliminating interference noise. Finally, based on the one-dimensional steady heat transfer theory, the principle of quantitative detection of heat transfer coefficient in infrared image is given by studying the heat transfer process of the wall, and the related correction method is designed. The feasibility and superiority of this method are illustrated by an example. Therefore, this method has good application prospects in building energy-saving detection.

To tune CH4 selectivity of Fe-based Fischer-Tropsch synthesis (FTS) in the initial stage is of prime scientific and industrial importance to further improve the catalyst performance. Herein, distribution of CH4 selectivity on the metallic Fe nanoparticle is predicted by DFT calculations and micro-kinetics analysis about the competition between C1 hydrogenations and C1 + C1 couplings on abundant Fe surfaces including Fe(1 0 0), Fe(1 1 0), Fe(1 1 1), Fe(2 1 1), and Fe(3 1 0). The results show that HCO mechanism (HCO → CH + O) is an available source of C1 species apart from CO direct dissociation. These Fe surfaces exhibit high effective barriers for CH4 formation, which is linearly correlated to the thermal stability of CH2 species. However, carbon chain prolongation on the more stable surfaces greatly depends on the coupling of C and CH species. On the less stable Fe(1 1 1) surface, the CO + C coupling is the main route for chain prolongation. Utilizing the effective barrier difference between the CH4 formation and the most feasible C1 + C1 coupling as a descriptor of CH4 selectivity, it is quantified that CH4 selectivity decreases in sequence of Fe(1 0 0) > Fe(2 1 1) > Fe(1 1 0) > Fe(3 1 0) > Fe(1 1 1). It is revealed that thermal stability of the CH2 species and exposition of the Fe facets could play essential roles in tuning CH4 selectivity. Trying to expand the area of Fe(2 1 1), Fe(3 1 0) and especially Fe(1 1 1) surfaces would greatly suppress CH4 selectivity without a decrease of activity. This work provides new insights and design principles for the Fe-based FTS catalysts.

Tin-assisted fully exposed Pt clusters are fabricated on the core–shell nanodiamond@graphene (ND@G) hybrid support (a-PtSn/ND@G). The obtained atomically dispersed Pt clusters, with an average Pt a...

Iron carbide phase formation during carburization of α-Fe catalysts were studied using in situ XRD, where the effect of varying carbon chemical potentials of CO/syngas/C 2 H 4 /C 2 H 2 gases and potassium promoter on the carburization behaviors was studied. The actual carburization capability of these gases follows an order of 2% CO/He 2 H 4 /He 2 /He 2 H 2 /He, which does not correlate well with the theoretical carbon chemical potential. In addition, the carburization rate and the formation of carbon-rich iron carbides are favored by potassium under CO or syngas, while inhibited by potassium under C 2 H 4 or C 2 H 2 . Temperature programmed carburization together with pulse experiments and DFT calculations indicate that the potassium promoter could weaken the adsorption ability of the C 2 H 4 and C 2 H 2 and thus reduce their carburization capabilities.

Dissociation of CO often occurs on Ru surfaces with dense chemisorbed CO (CO*) adlayers, ubiquitous in the practice of catalysis, where the strong bond in CO tends to weaken via bimolecular reactions with H2 before cleavage. Nevertheless, H2 adsorption on CO*-crowded Ru surfaces is a rare event because of the CO*-induced barrier and the competitive adsorption between CO and H2. Here, we thereby performed a comprehensive ab initio study of the coadsorption of CO and H2 as well as the following initiation reaction on Ru(0001). At 100–550 K (3 MPa, H2/CO = 2), Ru(0001) is always saturated, covered by CO with a “hexagonal” pattern, where H2 adsorption is neither kinetically nor thermodynamically favored. On the basis of a systematic analysis of the electronic structure, we find that two adjacent coadsorbed CO* can serve as a promoter for the scission of the H–H bond in H2(g), leading to the simultaneous formation of two COH* molecules in one step (Ea = 1.64 eV). This so-called CO self-promoting hydrogenation ...

CO adsorption on the perfect Ir(111) as well as the unreconstructed Ir(100) and Ir(110) surfaces at different coverages has been computed at the level of periodic density functional theory. General...

The morphology change of metallic nanoparticles induced by the interaction of gas molecules with nanoparticles is a very important surface chemistry process in heterogeneous catalysis. Here, we performed a thorough study to provide understanding of the influence of CO adsorption on theoretically established Ru nanoparticle models through an approach combining density functional theory, Wulff construction, and ab initio atomistic thermodynamics. The morphology of constructed Ru nanoparticles undergoes significant evolution upon changing CO coverage, exposed temperature, and pressure. The contribution from flat facets becomes more significant in equilibrium morphology of nanoparticles as the surface CO coverage increases. Such morphological evolution has a consequential impact on the inherited catalytic performance of Ru NPs, as they were applied into three probe catalytic reactions, CO direct dissociation, HCO formation, and CH3 hydrogenation. This study enriches the current knowledge of the ruthenium nano...