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The simplified governing equations of applied mechanics play a pivotal role and were derived based on ingenious assumptions or hypotheses regarding the displacement fields for specific problems. In this paper, we introduce a data-driven method by the name AI-Timoshenko in honor of Timoshenko, father of applied solid mechanics, to automatically discover simplified governing equations for applied mechanics problems directly from discrete data simulated by the three-dimensional (3D) finite element method. The simplified governing equations are in variational form, which is compact and advantageous for data-driven discovery. AI-Timoshenko liberates applied mechanicians from burdensome labor, including assumptions, derivation, and trial and error. The simplified governing equations for Euler-Bernoulli and Timoshenko beam theories are successfully rediscovered using the present AI-Timoshenko method, which shows that this method is capable of discovering simplified governing equations for applied mechanics problems. [ABSTRACT FROM AUTHOR]

Nidirana guangxiensis sp. nov., a new music frog species, is proposed, based on a series of specimens collected from Mt Daming, Guangxi, southern China. The new species is close to N. yeae, N. daunchina, N. yaoica, and N. chapaensis from southwestern and south-central China and northern Indochina, while the relationships among these species remain unresolved. Nidirana guangxiensis sp. nov. can be distinguished from all known congeners by the genetic divergences in the mitochondrial 16S and COI genes, the behavior of nest construction, the advertisement call containing 6-11 rapidly repeated regular notes, and a combination of morphological characteristics. Furthermore, the Nidirana populations recorded in Guangxi are clarified in this work, providing valuable new information on the knowledge of the genus Nidirana. [ABSTRACT FROM AUTHOR]

Objective: Esophageal squamous cell carcinoma (ESCC) has high morbidity and mortality rates worldwide. Cancer stem cells (CSCs) may cause tumor initiation, metastasis, and recurrence and are also responsible for chemotherapy and radiotherapy failures. Myeloid-derived suppressor cells (MDSCs), in contrast, are known to be involved in mediating immunosuppression. Here, we aimed to investigate the mechanisms of interaction of CSCs and MDSCs in the tumor microenvironment. Methods: ESCC tissues and cell lines were evaluated. Neural precursor cell expressed, developmentally downregulated 9 (NEDD9) was knocked down and overexpressed by lentiviral transfection. Quantitative PCR, Western blot, immunohistochemistry, cell invasion, flow cytometry, cell sorting, multiplex chemokine profiling, and tumor growth analyses were performed. Results: Microarray analysis revealed 10 upregulated genes in esophageal CSCs. Only NEDD9 was upregulated in CSCs using the sphere-forming method. NEDD9 expression was correlated with tumor invasion (P = 0.0218), differentiation (P = 0.0153), and poor prognosis (P = 0.0373). Additionally, NEDD9 was required to maintain the stem-like phenotype. Screening of chemokine expression in ESCC cells with NEDD9 overexpression and knockdown showed that NEDD9 regulated C-X-C motif chemokine ligand 8 (CXCL8) expression via the ERK pathway. CXCL8 mediated the recruitment of MDSCs induced by NEDD9 in vitro and in vivo. MDSCs promoted the stemness of ESCC cells through NEDD9 via the Notch pathway. Conclusions: As a marker of ESCC, NEDD9 maintained the stemness of ESCC cells and regulated CXCL8 through the ERK pathway to recruit MDSCs into the tumor, suggesting NEDD9 as a therapeutic target and novel prognostic marker for ESCC. [ABSTRACT FROM AUTHOR]

Nano/ultrafine-grained 18Cr–8Ni stainless steel was produced by severe cold deformation followed by annealing. The effect of annealing temperature on the fraction of high-angle grain boundaries (HAGBs), the kernel average misorientation (KAM), and Schmid factor of steels are revealed through electron backscatter diffraction analysis. The analysis on HAGB, KAM values and Schmid factor frequency provide a mechanistic understanding of the impact of structure on mechanical properties, including hardness, strength, toughness and ductility. In this study, a novel application of persistent homology (PH) was employed to reduce the dimensionality of the information describing the complex processing-structure-property relationship. PH emphasizes the relationship between processing (annealing temperature), structure (distribution of the Schmid factor) and property (strength). Specifically, the PH formalism translates multidimensional data sets into clusters, distinguished by common PH features. In this analysis, two clusters emerge. First, at low annealing temperature, incomplete reversion of austenite in austenitic stainless steels results in materials with a greater fraction of grain boundaries, resulting in high strength and low ductility. Second, at high annealing temperature, fully reversed austenite results in lower, though still acceptable strength and superior ductility. The PH approach is applicable for identifying salient features in complex processing-structure-property relationships and is amenable to analysis of large data sets based on machine learning. [ABSTRACT FROM AUTHOR]

Progranulin (PGRN) is a neurotrophic and anti-inflammatory factor with protective effects in animal models of ischemic stroke, subarachnoid hemorrhage, and traumatic brain injury (TBI). Administration of recombinant (r) PGRN prevents exaggerated brain pathology after TBI in Grn-deficient mice, suggesting that local injection of recombinant progranulin (rPGRN) provides therapeutic benefit in the acute phase of TBI. To test this hypothesis, we subjected adult male C57Bl/6N mice to the controlled cortical impact model of TBI, administered a single dose of rPGRN intracerebroventricularly (ICV) shortly before the injury, and examined behavioral and biological effects up to 5 days post injury (dpi). The anti-inflammatory bioactivity of rPGRN was confirmed by its capability to inhibit the inflammation-induced hypertrophy of murine primary microglia and astrocytes in vitro. In C57Bl/6N mice, however, ICV administration of rPGRN failed to attenuate behavioral deficits over the 5-day observation period. (Immuno)histological gene and protein expression analyses at 5 dpi did not reveal a therapeutic benefit in terms of brain injury size, brain inflammation, glia activation, cell numbers in neurogenic niches, and neuronal damage. Instead, we observed a failure of TBI-induced mRNA upregulation of the tight junction protein occludin and increased extravasation of serum immunoglobulin G into the brain parenchyma at 5 dpi. In conclusion, single ICV administration of rPGRN had not the expected protective effects in the acute phase of murine TBI, but appeared to cause an aggravation of blood-brain barrier disruption. The data raise questions about putative PGRN-boosting approaches in other types of brain injuries and disease. [ABSTRACT FROM AUTHOR]

Based on combined morphological and osteological characters and molecular phylogenetics, we describe a new species of the genus Elaphe that was discovered from the south slope of the Qinling Mountains, Shaanxi, China, namely Elaphe xiphodonta sp. nov. It is distinguished from the other congeners by a combination of the following characters: dorsal scales in 21-21-17 rows, the medial 11 rows keeled; 202-204 ventral scales, 67-68 subcaudals; two preoculars (including one subpreocular); two postoculars; two anterior temporals, three posterior temporals; reduced numbers of maxillary teeth (9+2) and dentary teeth (12); sharp cutting edges on the posterior or posterolateral surface of the rear maxillary teeth and dentary teeth; dorsal head yellow, three distinct markings on the head and neck; a distinct black labial spot present in supralabials; dorsum yellow, 46-49 complete (or incomplete) large black-edged reddish brown blotches on the body and 12-19 on the tail, two rows of smaller blotches on each ventrolateral side; ventral scales yellow with mottled irregular black blotches, a few irregular small red spots dispersed on the middle of the ventral. Based on molecular phylogenetic analyses, the new species forms the sister taxon to E. zoigeensis. The discovery of this new species increases the number of the recognized species in the genus Elaphe to 17. [ABSTRACT FROM AUTHOR]

Powdery mildew (PM) is a major fungal disease in the Cucurbita species in the world, which can cause significant yield loss. The Mildew Locus O (MLO) family genes play important roles in the PM stress response. In this paper, twenty, twenty-one, and eighteen candidate MLO genes in Cucurbita moschata, Cucurbita maxima and Cucurbita pepo, respectively, were identified and designated as CmoMLO, CmaMLO and CpeMLO, respectively. The phylogenetic analysis indicated that these MLOs were divided into five clades and the number of MLOs belonging to clade V in the Cucurbita species was more than that in other crops. Furthermore, the expression analysis in the susceptibility (S) and resistance (R) lines showed that CpeMLO1, CpeMLO2 and CpeMLO5 might be involved in the susceptibility response. CpeMLO4 and CpeMLO6 showing opposite expression patterns in the R/S lines might be involved in the resistance response. All these data would be beneficial for future functional analysis of MLOs in the Cucurbita species. [ABSTRACT FROM AUTHOR]

[Display omitted] • AA-TFCW accelerated NH 4 +-N transformation with 6.68 mg/(L·h) in start-up phases. • Heterotroph and autotroph synergistically removed 74.2% TN at low temperature. • HN-AD bacteria achieved direct NH 4 +-N removal by nitrate assimilation pathway. • Ferribacterium and Nitrosomonas carried high-weight key genes for N removal. This study explored the quantitative mechanisms of heterotrophic nitrification-aerobic denitrification (HN-AD) in a pilot-scale two-stage tidal flow constructed wetland (TFCW). The TFCW packed shale ceramsite (SC) and activated alumina (AA) at each stage, respectively, and aimed to improve decentralized wastewater treatment efficiency. In start-up phases, AA-TFCW accelerated NH 4 +-N decline, reaching transformation rates of 6.68 mg NH 4 +-N/(L·h). In stable phases, SC-AA-TFCW resisted low-temperatures (<13 °C), achieving stable NH 4 +-N and TN removal with effluents ranging 6.36–8.13 mg/L and 9.43–14.7 mg/L, respectively. The dominant genus, Ferribacterium, was the core of HN-AD bacteria, simultaneously removing NH 4 +-N and NO 3 –-N by nitrate assimilation and complete denitrification (NO 3 –-N → N 2), respectively. The quantitative associations highlighted importance of nitrification, nitrate assimilation, and denitrification in nitrogen removal. HN-AD bacteria (e.g., Lactococcus , Thauera , and Aeromonas) carried high-weight genes in quantitative associations, including nap AB, nas A and glt BD, implying that HN-AD bacteria have multiple roles in SC-AA-TFCW operation. [ABSTRACT FROM AUTHOR]

Neighbourhood-based collaborative filtering (CF) methods typically rely only on user rating information for similarity calculation, without considering linguistic concepts (terms) that reflect user fuzzy preferences. However, in real-world decision-making processes, users often prefer to express their preferences for items linguistically rather than numerically. Inspired by this, we propose a probabilistic linguistic term set–based item similarity method that transforms absolute ratings into linguistic terms to capture the degree of importance users place on explicit aspects and opinions. Furthermore, we take into account the positive impact of users’ preferred consistency towards items on similarity results and introduce a Bhattacharyya coefficient–based item tendency to adjust semantic similarities, enhancing the reliability of predictions. In addition, we account for the asymmetric relation between items when selecting appropriate neighbours to optimise rating predictions. The experiments on two benchmark data sets indicate that our method outperforms existing similarity methods across various evaluation metrics. Specifically, compared with the state-of-the-art method, intuitionistic fuzzy set–based hybrid similarity model (IFS-HSM), the proposed model improves the performance by at least 2.1% and 1.9%, respectively, within the metrics mean absolute error (MAE) and F1. Moreover, our approach provides a new insight for measuring similarity between items from both qualitative and quantitative perspectives. [ABSTRACT FROM AUTHOR]

In the face of a growing global population, climate change, and limited arable land, the need for resilient, high-yielding crops is pressing. Traditional breeding methods have struggled to meet these demands, but CRISPR/Cas9-based genome editing offers a groundbreaking solution. This article provides an in-depth overview of CRISPR/Cas9's role in enhancing crop traits to ensure global food security. By harnessing modern sequencing technologies, researchers can precisely edit genes in crop plants especially major crops like Triticum aestivum, Oryza sativa, Zea mays, and Solanum tuberosum etc., imparting traits such as disease resistance and stress tolerance. The technology is pivotal to producing next-generation crops (NGC's) capable of adapting to changing climates and delivering higher yields and product quality. Ethical and regulatory considerations are important, but responsible governance of genome editing promises significant advancements in agriculture. This review highlights CRISPR/Cas9's transformative potential in crop improvement and its pivotal role in shaping the future of food production. • This review covers the current state of CRISPR/Cas9 in crop enhancement, its potential role in addressing global food security, and future perspectives. • Modern sequencing technologies reveal plant genetic complexities, which can be combined with CRISPR-based genome editing for crop improvement. • Important crop traits, like disease resistance, yield, and stress tolerance, are being enhanced in various species such as Triticum aestivum , Oryza sativa , Zea mays , and Solanum tuberosum. • The review will explain the origin, architecture, and mechanism of CRISPR/Cas9. • The substantial contributions of CRISPR/Cas9 to agriculture and its potential future role in ensuring global food security are emphasized. [ABSTRACT FROM AUTHOR]

[Display omitted] • CO 2 hydrogenation over inverse supported Zr 9 O 18 /Ni(1 1 1) nanocatalyst was computed. • Charge transfer from Ni(1 1 1) to supported Zr 9 O 18 nanoparticle has been found. • Supported Zr 9 O 18 nanoparticle has coordinatively unsaturated Zr sites at interface. • H 2 prefers dissociative adsorption on Ni(1 1 1) and CO 2 activation prefers interface Zr sites. • Surface HCOO is the most important intermediate and methanol is the selective product. To tune the activity and selectivity of CO 2 hydrogenation, inverse supported Zr 9 O 18 /Ni(1 1 1) catalysts are designed based on ab initio molecular dynamics simulation and density functional theory calculation under the consideration of the number of interfacial O and Zr atoms as well as the interaction between O and Zr atoms. For the most stable catalyst with coordinatively unsaturated interface Zr sites, charge transfer from surface to oxide has been found. The Ni(1 1 1) surface is pre-covered by H atoms and the interface Zr sites can activate CO 2 to a large extent, and their interaction results in the spontaneous formation of surface formate. Further hydrogenation of surface formate leads to the selective formation of methanol with an apparent Gibbs free energy barrier of 0.62 eV, lower than that of methane formation (1.09 eV). On the contrary to metallic nickel and supported nickel catalysts, the most favoured methanol formation route [HCOO → CHO → CH 2 O → CH 3 O → CH 3 OH] does not involve CO as intermediate, revealing the mediated interface effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Temperature-dependent ethylene dissociative adsorption on ruthenium was computed quantitatively. • Revised PBE can best quantify the adsorption energy of ethylene, H 2 and CO. • Computed activation barriers of the dissociation of CH 2 CH 2 * and CH 3 C* agree quantitively with experiments. • CO co-adsorption stabilizes CH 3 C* by blocking surface sites and raising the dissociation barrier. • BEP relationship is found for the formation of CH 3 C* and HCC under the co-adsorbed CO and hydrogen. The dissociative adsorption of ethylene onto Ru(1 1 1) at different temperatures was computed systematically at the first time. At 105 K, ethylene dissociative adsorption has the co-adsorbed CH 2 C*+2H* and CH 3 C*+H* as the first and second stable surface intermediates. At over 330 K, CH 3 C*+H* is converted back into CH 2 C* accompanied by H 2 desorption and the subsequent dissociation of CH 2 C* into HCC*, HC*+C* and 2C*. The computed Arrhenius activation barriers of the dissociation of CH 2 CH 2 (0.18 vs. 0.22 ± 0.04 eV) and CH 3 C (0.54 vs. 0.52 ± 0.04 eV) agree perfectly with the available experimental values, and CH 3 C* represents the most stable surface species. Under CO co-adsorption, the most stable surface species are the co-adsorbed CH 3 C*+H*+3CO*. It is found that CO co-adsorption promotes H 2 desorption and stabilizes CH 3 C* by blocking the surface sites for dissociation and raises the dissociation barrier compared to the clean surface (0.78 vs 0.54 eV). Brønsted–Evans–Polanyi relationship between the activation Gibbs free energy barrier and reaction Gibbs free energy is found for CH 2 C*+2H*+ n CO* = CH 3 C*+H*+ n CO* and CH 2 C*+2H*+ n CO* = HCC*+3H*+ n CO* (n = 0–3). Ethylene adsorption has di-σ and π adsorption configurations in very close energy, and H 2 has adsorption energy of about 0.90 eV. [ABSTRACT FROM AUTHOR]

The genetic origins of nanoscale extracellular vesicles in our body fluids remains unclear. Here, we perform a tracking analysis of urinary exosomes via RNA sequencing, revealing that urine exosomes mostly express tissue-specific genes for the bladder and have close cell-genetic relationships to the endothelial cell, basal cell, monocyte, and dendritic cell. Tracking the differentially expressed genes of cancers and corresponding enrichment analysis show urine exosomes are intensively involved in immune activities, indicating that they may be harnessed as reliable biomarkers of noninvasive liquid biopsy in cancer genomic diagnostics and precision medicine. [ABSTRACT FROM AUTHOR]

[Display omitted] • A theoretical model is proposed to study the peeling of heterogeneous film. • Nine kinds of peeling processes for heterogeneous film are uncovered. • Two kinds of peeling processes experience two peeling instabilities within one peeling period. • An optimal length fraction of stiff section exists for enhancing adhesive performance. • Better adhesion performance enhancement can be achieved by using more flexible film. Although it has been demonstrated that heterogeneous film can enhance adhesion properties without modifying the interface, there is still a dearth of comprehensive studies in the literature regarding the peeling process of such film and the potential instability that may occur during the peeling process. To address these issues, a peeling model based on the cohesion zone model and Euler-Bernoulli beam equation is proposed in this study. Our analysis revealed four previously unknown peeling behaviors: Firstly, there are nine kinds of peeling processes for heterogeneous film. Only one is stable, static peeling process, while the other eight exhibit instability when the peeling front reaches a certain position. Secondly, instability may occur at the interface from the stiff section to the compliant section of the homogeneous film, as well as at stiff section or compliant section. Moreover, two of these peeling processes experience two instabilities within one peeling period – one at the interface from the stiff section to the compliant section and another at stiff section. Thirdly, an optimal length fraction of the stiff section for enhancing adhesive performance exists and its value is largely determined by the strength of the interface material. Specifically, higher interfacial strength results in smaller values of the optimal length fraction. Finally, the maximum peeling force is positively correlated with the bending stiffness ratio, interfacial strength, interfacial toughness, and period length of heterogeneous film. But it is inversely related to the bending stiffness. These findings are crucial for understanding the peeling behavior of heterogeneous film and strongly adhesive interfaces found in nature, and can be applied to optimize adhesive design and performance in practical engineering applications. [ABSTRACT FROM AUTHOR]

The abnormal lipid metabolism in diabetic cardiomyopathy can cause myocardial mitochondrial dysfunction, lipotoxicity, abnormal death of myocardial cells, and myocardial remodeling. Mitochondrial homeostasis and normal lipid metabolism can effectively slow down the development of diabetic cardiomyopathy. Recent studies have shown that SIRT6 may play an important role in the pathological changes of diabetic cardiomyopathy such as myocardial cell death, myocardial hypertrophy, and myocardial fibrosis by regulating mitochondrial oxidative stress and glucose and lipid metabolism. Therefore, understanding the function of SIRT6 and its role in the pathogenesis of diabetic cardiomyopathy is of great significance for exploring and developing new targets and drugs for the treatment of diabetic cardiomyopathy. This article reviews the latest findings of SIRT6 in the pathogenesis of diabetic cardiomyopathy, focusing on the regulation of mitochondria and lipid metabolism by SIRT6 to explore potential clinical treatments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Real space evidence of p4g(2 × 2) Fe 2 C and Co 2 C surface carbides. • Tip-sample distance dependent STM imaging of Fe 2 C. • Fe 2 X (X = B, C, N, O) with increasing electrons the reconstruction becomes less favourable. Thin FCC (1 0 0) iron and cobalt carbide films were prepared on Cu(1 0 0) to study the connection between their structure, electronic properties and stability. We present the first detailed, real space experimental confirmation of the C-induced clock reconstruction on the FCC(1 0 0) surfaces of iron and cobalt. Both Fe and Co surface carbides show p4g (2 × 2) surface reconstruction with tetracoordinated square planar carbon and pure FCC (1 0 0) metal layers underneath. Combining tip-sample distance dependent STM imaging with theoretical calculations we present different imaging modes of Fe 2 C. Using a combination of angle-resolved x-ray photoelectron spectroscopy (AR-XPS), Auger electron spectroscopy (AES), low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and theoretical calculations we provide detailed electronic and structural models for Fe 2 C and Co 2 C p4g (2 × 2) surface carbides and other 2D Fe 2 X interstitial compound systems. In various Fe 2 X (X = B, C, N, O) surface compounds moving to the right in the periodic table with increasing electrons the reconstruction becomes less favorable, while iron carbide shows the highest stability. [ABSTRACT FROM AUTHOR]

[Display omitted] The niche breadth, niche overlap, and interspecific associations of species in Bayinbuluke alpine meadow were investigated using ecology statistics to explore the competitive connection between the species and restricted resources in the community and the stable coexistence relationships among populations under different nitrogen addition gradients in the short term. The findings demonstrate the following. (1) The importance value of species shifted, with the fertilization samples Festuca ovina and Poa annua becoming the species with the highest importance value. Species richness fell gradually as fertilization gradient progressed, while the number of species grew initially and subsequently decreased. (2) Under different fertilization methods, the niche width and niche overlap values of the principal species changed. A positive link was found between niche width values and critical values under fertilization treatment compared with the controls. (3) By using the variance ratio approach, Pearson's correlation, and the association coefficient test, a positive correlation was discovered among species under low fertilization gradient treatment. However, a negative correlation was found under other gradients. [ABSTRACT FROM AUTHOR]

The seawater dry water extinguishing materials formed by coating seawater with nano-SiO 2 have greatly enlarged the application space of the seawater as a fire-extinguishing medium. Against the deficiencies in the evaluation of the size-fractionated and stability of dry water extinguishing materials, especially of the coating effect of nano-SiO 2 , this study designed an airflow size-fractionated system applicable to dry water materials and characterized the stability of dry water materials by electrochemical methods according to the pneumatic separation principle. The results showed that the grain size range of seawater@nano-SiO 2 dry water extinguishing materials was 0.2–400 μm, and that the dry water could be divided into three intervals by granule size by adjusting the turbo-dynamo frequency and draught fan frequency of the airflow size-fractionated system. The electrochemical methods are applicable to describe the stability of the dry water extinguishing materials, and the gelatinization of core material can significantly make up for the deficiency that the core material of dry water tends to separate out over storage time. However, the stability of dry water is subject to granule size more than the gelatinization of the core material, and the dry water with big-size granules has optimal stability. Graded dry water is less corrosive to aluminum sheets, and the corrosion resistance to big-grained gel-dry water is optimal. The research conclusion can provide a technical basis for size-fractionated and covering effect characterization of dry water extinguishing materials and for type selection of storage media. • The stability of dry water is characterized by the electrochemical methods. • The size-fractionated of dry water is optimized by using improved airflow system. • Better stability and anticorrosive properties contain more larger GDW particles. [ABSTRACT FROM AUTHOR]

[Display omitted] • CO 2 Conversion to CH 4 and CH 3 OH on ZrO 2 support Ni catalysis was computed. • Metal-Metal and Metal-support Interaction was analysed. • Reaction Mechanisms, differently from metallic Ni, were identified. • Metal interaction determines structure of support Ni and reaction mechanisms. To better understand the metal-support interaction and structure–activity relationship, we computed the mechanisms of CO 2 hydrogenation to CH 4 and CH 3 OH on ZrO 2 supported Ni catalyst. On a supported irregular Ni 13 cluster, which exhibits a balanced metal–metal and metal-support interaction with surface Zr and O atoms covered, two preferred routes [CO 2 → CO → CHO → CH/CH 3 O → CH 3 → CH 4 /CH 3 OH] are found, and the rate-determining step is the CO 2 direct dissociation. Such mechanisms differ very strongly from those reported on flat metallic Ni(1 1 1) surface and Ni clusters supported on different metal oxides, demonstrating that different supports generate different metal-support interaction that simultaneously changes the metal structures and the reaction mechanisms. [ABSTRACT FROM AUTHOR]

In petrochemical industry, zeolites as solid acid catalysts play an important role and Y zeolites with high surface area and large pore openings are mainly used for catalytic cracking. Aiming at the problem that the specific positions of Al atoms in zeolites cannot be accurately distinguished experimentally and the acid strength can only be studied qualitatively, we used computational model and method to study the position of Al substitution and the resulted acid strength of Y zeolite at atomic and molecular level. The position of Al substitution with gradually decreasing Si/Al ratio (Si/Al = 47–2.4) and the corresponding Brønsted acid strength of the resulting multiple acid sites of HY zeolites are systematically investigated based on periodic DFT calculation including dispersion correction (GGA-PBE-D3). The thermodynamically more stable structures prefer Al distribution having the next-nearest neighbor of aluminum atom pairs (Al–O–Si–O–Al), and based on these stable configurations, the adsorption of ammonia (NH 3) and pyridine (C 5 H 5 N) has been computed to estimate the Brønsted acid strength. It is found that the adsorption of NH 3 and C 5 H 5 N prefers the formation of ammonium (NH 4 +) and pyridinium (C 5 H 5 NH+) ions at each acid sites and the adsorption enthalpy does not correlate with the Bader charge of the acid proton. Most importantly, the adsorption enthalpy decreases with the decrease of Si/Al ratio, indicating that the more the Al substitution the weaker the Brønsted acid strength. It is noted that the adsorption enthalpy of all individual acid sites at a given Si/Al ratio can differ strongly, despite the formation of NH 4 + and C 5 H 5 NH + ions, indicating their mutual interaction and local confinement effect. The calculated adsorption enthalpies agree fully with the experimentally measured results (Si/Al = 8.6–2.4). Hyroxyl nest, defect sites formed from dealumination, has much weaker acid strength than the Brønsted acid sites. Our results provide a rational basis for further studies on the enhanced catalytic activity of HY zeolites with different Si/Al ratios. [Display omitted] • Structure and stability of Y-Zeolite with multiple Al substitution were computed using DFT. • The stability of Al distribution prefers the next-nearest neighbor of aluminum atom pairs. • The acid strength was computed based on the adsorption enthalpy of ammonia (NH 4 +) and pyridine (C 5 H 5 NH+). • The adsorption enthalpy decreases with the decrease of Si/Al ratio. • The more the Al substitution the weaker the Brønsted acid strength. [ABSTRACT FROM AUTHOR]

• The mechanism for eliminating adsorbed oxygen by the reduction with H and CO on χ-Fe 5 C 2 surfaces was investigated. • The removal mechanism shows diversity over different facets. • Carbon-rich surface exhibits higher barriers to direct CO 2 formation, like (110) and (111). The removal of surface oxygen adsorbed on iron carbides is essential to protect the nanoparticle from oxidation in heterogeneous catalysis. Herein, we explored the removal of pre-adsorbed oxygen on seven facets of χ-Fe 5 C 2, and four pathways including both direct and indirect routes for generating H 2 O and CO 2 were investigated. The removal mechanism shows diversity over different facets. On (010), the formation of CO 2 through the reaction between surface oxygen and adsorbed CO is more favorable. While on (510), (001), (110), (11-1) and (-411), the elimination in the form of H 2 O through OH disproportionation dominates. In particular, surface oxygen can be removed facilely either in H 2 O or CO 2 on (111) surface. What's more, surface with more carbons exhibits higher barriers to direct CO 2 formation, like (110) and (111). Our work provides knowledge about mechanism of O removal and CO 2 formation, which may be helpful in protecting the nanoparticle from further oxidation. Graphical Abstract [Display omitted]. [ABSTRACT FROM AUTHOR]

[Display omitted] • The morphology evolution of Hägg carbide Fe 5 C 2 under hydrogen conditions was explored. • Carbon-rich facets expose more area surface in Wulff construction with decreasing hydrogen chemical potential, while iron-rich facets are in contrast. • The reduction of surface carbon to methane for (1 1 1) and (11-1) facets is more facile than other facets. In heterogeneous catalysis, the interaction between adsorbates and substrate surface plays an important role on surface structure evolution and even the reaction mechanism. Herein, unified DFT calculation and ab initio atomistic thermodynamics were adopted to explore the interaction between hydrogen and multiple Fe 5 C 2 surfaces. The computation indicates that the dissociation of hydrogen molecule is both thermodynamically and kinetically favorable on Fe 5 C 2 surfaces. The adsorption energy of hydrogen atoms is related to the summed H bond valance (SBV H), a higher SBV H corresponding to a more stable adsorption strength. Based on calculated surface free energy with different hydrogen coverage, the equilibrium crystalline morphology evolution of Fe 5 C 2 under dynamic conditions was constructed with Wulff theorem. C-rich facets expose more area in Wulff construction with decreasing hydrogen chemical potential. The generation of carbon vacancy through reducing to methane has also been investigated, and the reduction of (1 1 1) and (11-1) facets is more facile than other facets. We anticipate this work could complement some knowledge to help understanding the surface structure and performance of iron carbide catalysts under experimental conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Main features of GDOES, XPS and ToF-SIMS depth profiling of the thin amine polymer film are compared. • GDOES depth profiling in Ar/O 2 mixture increases etching rate and depth resolution for amine polymer film compared to pure Ar gas. • Etching of polymer surface by glow discharge of Ar/O 2 mixture is based on the synergy of ion sputtering and reactive chemical etching. • GDOES depth profiling is suitable for fast analyses of polymer layers up to a few μm in thickness. Thin polymer films were deposited on polished stainless-steel samples by PECVD from a cyclopropylamine precursor and characterized by X-ray photoelectron spectroscopy, secondary-ion mass spectrometry and glow-discharge optical emission spectroscopy (GDOES) depth profiling. These depth profiles exhibited reasonable agreement. The GDOES involved the erosion of the polymer films in plasma sustained by an asymmetric RF capacitively coupled discharge using both Ar and Ar-O 2 gases. The application of pure Ar caused unwanted effects, such as the broadening of the polymer-film/substrate interface, which were suppressed when using the mixture with oxygen. Another benefit of oxygen was a significant increase in the etching rate by a factor of about 15 as compared to pure argon. The mechanisms involved in the depth profiling using the mixture of gases were elaborated in some detail, taking into account plasma parameters typical for an asymmetric, capacitively coupled RF discharge in a small volume. The main benefit of using the Ar/O 2 GDOES profiling with respect to XPS and SIMS depth profiling is the increased sputtering rate for polymer films. Comparing the GDOES depth profiling with the Ar/O 2 mixture with profiling in pure Ar, the benefits are a higher sputtering rate and better depth resolution at the polymer/substrate interface. [ABSTRACT FROM AUTHOR]

Sn-containing Fe 5 C 2 interface not only can boost the rates of oxygen removal but also restrain the coke deposition by elevating the barrier of nucleation, which stabilizes the active iron carbide structure and enhanced the stability remarkablely. [Display omitted] • Oxygen removal by carbon oxide is facilitated for Fe-Sn interface； • Coking deposition was inhibited remarkably for Fe-Sn bimetallic catalysts; • Catalytic stability was significantly enhanced for Sn0.25 and Sn0.50 catalysts; • Provided a strategy to construct durable catalysts under the perspective of oxygen removal and coking resistance. Comprehending deactivation mechanisms and constructing durable Fe-based catalysts remain a substantial challenge for Fischer-Tropsch synthesis. In this contribution, the effects of Sn promoter on the structure and catalytic performance of Fe-based catalysts were investigated systematically. The catalytic stability was enhanced significantly for 100Fe/0.25Sn and 100Fe/0.50Sn catalysts, reducing the deactivation rate almost four-fold and seven-fold respectively. Combined with several characterizations and DFT calculation, it has been confirmed that Sn-containing Fe 5 C 2 interface not only can boost the rates of oxygen removal but also restrain the coke deposition by elevating the barrier of nucleation, which stabilizes the active iron carbide structure and inhibits the deactivation efficiently. This study may broaden the understanding of enhanced stability during Fe-based FTS under the perspective of oxygen removal and coking resistance and provide a strategy to construct durable catalysts. [ABSTRACT FROM AUTHOR]

The CO 2 formation mechanism on Fe x C y and its structure–reactivity relationship during sintering process were systemically elucidated using the ReaxFF. [Display omitted] • Investigate the structure-activity relationship of different Fe-based nanoparticles in the sintering process. • Formation of low-coordination-number atoms may be the real reason for promoted TOF of the sintering structures. • The increased amplitude of surface area of sintered Fe x C y varies with its content of carbon. • The main CO 2 formation varies with the Fe x C y : Eley-Rideal VS. Langmuir-Hinshelwood mechanism. The sintering of nanostructured catalysts poses a grand challenge in understanding the complex mechanism in the experimental phenomena, as well as the structure-activity relationship. Here, we systematically investigate the structure-activity relationship of sintered Fe-based catalysts, including Fe 2 C, Fe 5 C 2 , Fe 3 C and pure Fe, in the CO activation by reactive molecular dynamics simulations. The results show that the sintering structures can promote the turn-over frequency of Fe 3 C compared with its un-sintered near-size structures, which might be attributed to the formation of low-coordination-number atoms. The change of surface area shows a similar trend for Fe x C y and pure Fe, and its increased magnitude varies with the content of carbon in the Fe x C y bulk. For size effect, the Fe 2 C displays the largest turn-over frequency for the 4.34 nm particle. The CO 2 formation mechanism has also been compared for different Fe x C y , which may provide critical theoretical insights for industrial reduction of CO 2 emission. [ABSTRACT FROM AUTHOR]

Passive target detection under low signal-to-noise ratio is essential in various underwater circumstances, but difficult as lacking of targets' prior information, special propagation characteristics and effect of background noise. Based on the time–frequency representation, we develop a narrow band time–frequency space matched method. The time–frequency matrix is derived based on the ray theory, the warping expression, and the pooling function. Then the sliding cumulative convolution of the matrix obtains a higher signal to noise ratio output. The likelihood ratio test detector is derived for passive target detection. Analysis and the ocean experiment results show that the proposed approach outperforms other passive detectors. [ABSTRACT FROM AUTHOR]