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Improving the functionality of commercial plant proteins is essential for food application. Here an alternative strategy is provided to modify the structure of pea protein by microbial transglutaminase-induced cross-linking with whey protein for enhancing emulsifying and encapsulation properties. The protein structures and the physicochemical stability of 0-carotene-loaded emulsions were investigated subject to protein ratio and cross-linking. Formation of disulphide and isopeptide bonds between heteroproteins according to crosslinking changed protein structures by exposing the hydrophobic sites of proteins with stiffer network. The cross-linked pea/whey protein complexes at protein ratio of 2:1 formed a stable emulsion with a droplet size of 0.10 _m, showing no phase separation for 30 days of storage and high encapsulation efficiency of 92%. These findings provided a novel strategy to design plant/dairy protein networks to protect lipophilic bioactive compounds by replacing half or more dair-y protein with plant protein, leading to gradual change towards plant-based diets. [ABSTRACT FROM AUTHOR]

A gaseous hydrogen sulfide (H2S) oxidative removal technology by a dual ions-dual oxidants coupling activation system (i.e., Cu2*/Fe 2*/persulfate(PS)/H 2O2 coactivation system) was put forward. The fundamental issues, mainly including H2S removal performance, process parameters optimization, products, free radicals, synergy mechanism and desulfurization mechanism were studied systematically in a bubble column reactor. The study indicates that compared with Fenton system and non-coupling activation systems, the new dual ions-dual oxidants coupling coactivation system shows much higher free radical yield and H2S removal efficiency owing to significant synergistic activation effect. Higher concentrations of Cu2+ or Fe2+ greatly increase the H2S removal efficiency. With the increase of PS concentration, H2O2 concentration or reagent pH value, the H2S removal efficiency is first enhanced, and afterwards slightly declined. The H2S removal efficiency is declined via increasing operating temperature, gas flow rate and contents of H2S, SO2, NO and CO, and is almost not affected by content of Hg°. Sulfate, CuS and elemental sulfur are determined to be the products of H2S removal, and no by-products are produced after the reaction. Oxidation via -OH and S04'-plays a crucial role in H2S removal, which is proved to be the primary pathways of H2S removal. Finally, the recovery strategy of the products is discussed preliminarily. [ABSTRACT FROM AUTHOR]

The initial characteristics of the surface layer following the quenching and tempering treatment of ultra-high-strength steel play a significant role in determining the subsequent precision machining. This study focus on investigating the influence of machining processes on the quenching and tempering surface layer. The machining processes affect both the oxidation of the quenching and tempering treatment and the development of a distinct preferred grain orientation. Gradual diminishment of surface abrasions leads to the transformation of the needle-like oxidation pattern into a layered oxidation structure. The preferred orientation of the grains prevents the grains from shear sliding, thereby enhancing the Taylor effect. Formation mechanisms of the microhardness and residual stress of the quenching and tempering surface layer induced by machining processes were also discussed and completely revealed. The microhardness is mainly attributed to the dynamic Hall-Petch effect, while plastic strain, dislocation energy storage, and phase transformation contribute to the residual stress changes. • Formation mechanisms of the quenching and tempering surface layer induced by machining processes were revealed. • Machined surface morphology affects preferred grain orientation preference and austenitization characteristics. • Microhardness of the surface layer induced by machining processes is mainly attributed to the dynamic Hall-Petch effect. [ABSTRACT FROM AUTHOR]

High borated steels (HBSs) exhibit poor mechanical properties because brittle and coarse borides served as crack source during deformation, causing a premature failure. Here we proposed a novel strategy of tailoring strain hardening behaviour of metal matrix to enhance performance. Metastable austenite was introduced as matrix, where various deformation mechanism was obtained by manipulating deform temperature to change stacking fault energy (SFE). Unexpectedly, extraordinary strength-ductility synergy was achieved in HBSs with a moderate SFE at 100 °C. During hetero-deformation, hard borides caused serious stress gradients in austenite, triggering discontinuous transformation-induced plasticity effect. The cavities originating from fractured borides and interface debonding were arrested effectively by transformed martensite, which highly retarded the coalescence to form large cracks, allowing residual strain hardening to extend much longer to induce additional ductility. This work provides a new pathway to enhance strength-ductility synergy of materials containing many coarse and brittle secondary phases. [Display omitted] [ABSTRACT FROM AUTHOR]

Aiming at SDN-based storage environment, the integrity and availability of storage service are threatened by many attacks from data plane, such as packet tampering and dropping. While existing packet forwarding verification methods to deal with the sophisticated attacks are extremely limited due to the assumption that all or part of the switches are trusted. In this paper, for the untrusted data plane, a transparent gateway-based packet forwarding verification mechanism, named GwPFV, was designed to mitigate and trace back the attacks, specially utilizing the characteristics of TCP protocol to realize a packet obfuscation method to proactively defend attacks, a fast event-counting method to find attacks, and a path switching method involved with SDN controller to locate malicious switches. Finally, both the effectiveness and security of GwPFV are analyzed in depth. The experiments performed in an SDN-based prototype storage system reveal that it can achieve the security goal with relative low performance overhead. [ABSTRACT FROM AUTHOR]

A miniaturized, low-cost, 4-channel fiber Bragg grating (FBG) interrogation system for real-time remote monitoring is presented in this paper. A superluminescent light emitting diode (SLED) as the broadband light source combined with an interrogation module and an optical switch is applied in the system. The moving average method is employed to remove noise effects, and then Gaussian fitting method is used to realize the interrogation of FBG central wavelength with high precision. On software design, the WebSocket network protocol is introduced to establish communication between data processing core and webpages to achieve cross-platform remote access through the browser without user's software installation. The proposed interrogation system not only displays the reflected spectrum and demodulated central wavelength in real time on the webpage, but also realizes the data storage and channel switch remotely. The interrogator for remote monitoring of FBG sensors proposed in this paper has been proved experimentally with the interrogation resolution 0.1 pm, the precision of 5 pm for the FBG central wavelength, interrogation stability up to ± 1.1 pm, and interrogation frequency of 4 kHz. [ABSTRACT FROM AUTHOR]

Among the extensive repertoire of carbohydrate-active enzymes, lytic polysaccharide monooxygenases (LPMOs) have a key role in recalcitrant biomass degradation. LPMOs are copper-dependent enzymes that catalyze oxidative cleavage of glycosidic bonds in polysaccharides such as cellulose and chitin. Several LPMOs contain carbohydrate-binding modules (CBMs) that are known to promote LPMO efficiency. However, structural and functional properties of some CBMs remain unknown, and it is not clear why some LPMOs, like CjLPMO10A from the soil bacterium Cellvibrio japonicus, have multiple CBMs (CjCBM5 and CjCBM73). Here, we studied substrate binding by these two CBMs to shine light on their functional variation and determined the solution structures of both by NMR, which constitutes the first structure of a member of the CBM73 family. Chitin-binding experiments and molecular dynamics simulations showed that, while both CBMs bind crystalline chitin with Kd values in the micromolar range, CjCBM73 has higher affinity for chitin than CjCBM5. Furthermore, NMR titration experiments showed that CjCBM5 binds soluble chitohexaose, whereas no binding of CjCBM73 to this chitooligosaccharide was detected. These functional differences correlate with distinctly different arrangements of three conserved aromatic amino acids involved in substrate binding. In CjCBM5, these residues show a linear arrangement that seems compatible with the experimentally observed affinity for single chitin chains. On the other hand, the arrangement of these residues in CjCBM73 suggests a wider binding surface that may interact with several chitin chains. Taken together, these results provide insight into natural variation among related chitin-binding CBMs and the possible functional implications of such variation. [ABSTRACT FROM AUTHOR]

A considerable number of lytic polysaccharide monooxygenases (LPMOs) and other carbohydrate-active enzymes are modular, with catalytic domains being tethered to additional domains, such as carbohydrate-binding modules, by flexible linkers. While such linkers may affect the structure, function, and stability of the enzyme, their roles remain largely enigmatic, as do the reasons for natural variation in length and sequence. Here, we have explored linker functionality using the two-domain cellulose-active ScLPMO10C from Streptomyces coelicolor as a model system. In addition to investigating the WT enzyme, we engineered three linker variants to address the impact of both length and sequence and characterized these using small-angle X-ray scattering, NMR, molecular dynamics simulations, and functional assays. The resulting data revealed that, in the case of ScLPMO10C, linker length is the main determinant of linker conformation and enzyme performance. Both the WT and a serine-rich variant, which have the same linker length, demonstrated better performance compared with those with either a shorter linker or a longer linker. A highlight of our findings was the substantial thermostability observed in the serine-rich variant. Importantly, the linker affects thermal unfolding behavior and enzyme stability. In particular, unfolding studies show that the two domains unfold independently when mixed, whereas the full-length enzyme shows one cooperative unfolding transition, meaning that the impact of linkers in biomass-processing enzymes is more complex than mere structural tethering [ABSTRACT FROM AUTHOR]

• Polymorphism of formed NiO nanoparticles with size in 25-50 nm was observed. • High toxicity of nanoparticles was witnessed against MG-63 cancer cells. • NiO nanoparticles revealed high biocompatibility on HEK293 normal cells. • Nanoparticles showed bactericidal activity on various human pathogenic bacteria. The green synthesis of metal oxide nanoparticles is interestingly becoming familiar as the reason of its non-toxicity, economical, eco-friendly, and commerciality. The secondary metabolites and bioactive molecules in biomaterial extract play an important role of reducing, capping, stabilizing and chelating activities to form the nanoparticles as a substitute of hazardous chemical surfactants. Hence this present work concentrated on the biogenic synthesis of NiO nanoparticles using grains extract of Oryza longistaminata (red rice), and their toxicity assessment as well as biomedical applications. The synthesized nanoparticles were widely characterized by using several analytical and biomedical techniques. The reduction mechanism of Ni2+ ions using major active phytocompound in red rice grains extract was stated. UV–visible spectroscopic analysis revealed the formation of NiO nanoparticles by emerging the sharp surface Plasmon resonance band at 326 nm. The absorption peaks of red rice grains extract at 206, 260, 330 and 410 nm stated the presence of phytocompounds in them. X-ray diffraction pattern explicated the high crystallinity of NiO nanoparticles and their average crystallite size was found to be at 36 nm. The diffraction pattern of red rice grains revealed the amorphous characteristic. Fourier transform infrared analysis displayed the different vibrational functional groups of nanoparticles and red rice grains. Dynamic light scattering analysis showed the particle size distribution was in between 30-65 nm. High-resolution transmission electron microscopic analysis showed the hexagonal, rectangular, oval and spherical shaped polymorphism of NiO nanoparticles and their size was in 25-50 nm. Energy dispersive X-ray spectrum and mapping analyses validated the formation of NiO nanoparticles by the major existence of Ni and O elements. The high toxicity of nanoparticles towards MG-63 osteosarcoma cancer cells was revealed at 94.69% in 100 μg/mL concentration. The nanoparticles showed no severe toxicity against HEK293 normal cells and red blood cells till higher concentration. The biomedical analyses such as antioxidant, anti-inflammatory and anti-diabetic activities exposed the potential bio-drug activity of NiO nanoparticles with maximum activity of 86.22, 84.23 and 85.18% in the high concentration of 80 μg/mL. The antibacterial activity divulged the good bactericidal drug nature of NiO nanoparticles against both Gram-positive (S. aureus and B. Subtilis) and Gram-negative (S. typhi and K. pneumonia) bacteria with low MBC/MIC ratio. As per the assessment of results, the biosynthesized NiO nanoparticles have non-carcinogenic, high biocompatible and potent nature and it suggests that they can be used as therapeutic candidates in biomedical, clinical and pharmaceutical fields for treating various diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

Anticancer effect of prepared Cu (II) complexes on HepG2 liver cancer cells. [Display omitted] • [Cu(Phen)(Ida)](NO 3) 2 and [Cu(Phen) 2 (PABA)](NO 3) were synthesized. • Molecular docking study revealed the DNA binding of the Cu (II) complex. • Cu (II) complex demonstrated potent cytotoxicity on HepG2 cancer cells. • Cu (II) complex revealed antibacterial potential against human pathogens. • Cu (II) complex exhibited notable antifungal activity. The current work emphasizes the significance of a new copper (II) complex with [Cu(Phen)(Ida)](NO 3) 2 (Complex-1) [Cu(Phen) 2 (PABA)](NO 3) (Complex-2) (where Phen = 1;10-phenanthroline, Ida = Iminodiacetic acid, PABA = Para amino benzoic acid) has been synthesized and evaluated by using different analytical techniques. The binding mechanism of the Cu (II) complex with calf thymus DNA (CT-DNA) was understood from the UV and fluorescence spectra, as-well as cyclic voltammetry techniques. The stability of the Cu (II) complex was observed from the findings of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap. Additionally, molecular docking studies have revealed the binding affinity of the Cu (II) complex within the base pairs of CT-DNA. Subsequently, the Cu (II) complex was studied in cytotoxicity assessments using human liver cancer cells. The MTT assay was employed to evaluate cellular metabolic activity, and how it serves as an indicator while assessing the cell viability, proliferation, and cytotoxic effects. The resulting complex demonstrates significant cytotoxicity against HepG2 cancer cell lines. Furthermore, the complex has been investigated for its antibacterial potential against Gram-positive (Staphylococcus haemolyticus , Bacillus cereus) and Gram-negative (Enterobacter cloacae) bacteria. Also, it exhibits notable antifungal activity against fungi (TrichodermaViride , Clodosorium). The optimized findings indicate that the Cu (II) complex displays exceptional biological activities such as antibacterial, antifungal and anticancer properties. [ABSTRACT FROM AUTHOR]

• Excellent weld joints of high borated steels were produced by electron beam welding. • Weld joints with higher boron content tend to exhibit better mechanical properties. • Post weld heat treatment is a crucial step to fabricate high-performance weld joints. • A proper heat input is essential to obtain weld joints with better ductility. High borated stainless steels (HBSSs) are widely used in nuclear field because of excellent neutron-shielding ability. However, coarse network-like borides are prone to be formed in weld joints during welding process, deteriorating the ductility seriously. In this work, electron beam (EB) welding was adopted to join ∼3.5 mm thick HBSSs containing 0.30–2.12 wt. % boron. Benefiting from high energy density, fine γ-Fe matrix and network-like borides were obtained in fusion zone (FZ) and partially molten zone (PMZ) of weld joints. The effects of boron content, heat input and post weld heat treatment (PWHT) on the microstructure, mechanical properties and fracture behaviour of weld joints were investigated. As boron content increased, narrower PMZ was observed in weld joints owing to smaller solidification temperature range. The volume fraction and size of borides in PMZ/FZ raised, enhancing the strength and decreasing the ductility. Meanwhile, the fracture location of weld joints was closer to the interface of PMZ and base metal (BM) during deformation. Higher heat input brought a wider PMZ and larger penetration depth, but hardly changed the size and distribution of borides. Interestingly, it caused a steep slope of interfacial line between PMZ and BM, leading to the fracture along the interface with low ductility. After PWHT, the borides in PMZ/FZ were spheroidized, and the stress localization during deformation was weakened. Consequently, excellent weld joints exhibiting similar mechanical properties with base steels were produced. This systematic work provided a reference for welding other materials containing coarse and brittle secondary phases. [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]

[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]

[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]

[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]

[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]