Salt stress is a ubiquitous abiotic stress in nature and seriously affect woody plants growth and development. To explore how woody plants respond to salt stress, we used RNA-seq technology, ...time-course transcriptomics analysis, and constructed time-ordered gene co-expression networks (TO-GCNs) to analyze this mechanism using the poplar clone ‘84 K′ as the research object. Salt stress could increase the relative conductivity and plants damage degree, accumulate reactive oxygen species and malondialdehyde, decrease photosynthesis. In the constructed TO-GCNs, we divided the differentially expressed genes obtained by RNA-seq into six levels corresponding to the processing time points. Subnetworks containing transcription and non-transcription factors in photosynthesis, hyperosmotic salinity response, flavonoid biosynthesis process, abscisic acid (ABA)-activated signaling and cytokinin-activated signaling pathway were constructed, and the potential regulatory relationships between related genes and transcription factors were established. Thus, the potential regulatory mechanisms of transcription factors and response pathways were predicted. The results confirmed the regulation mechanism of woody plants under salt stress and revealed the potential regulatory relationship between transcription factors and response mechanisms in this process.
Display omitted
•Response mechanism of woody plants to salt stress.•The first application of time-ordered gene co-expression networks.•Potential regulation of TFs and no-TFs.•TFs involved in salt stress response pathway.
Formic acid‐induced controlled‐release hydrolysis of sugar‐rich microalgae (Scenedesmus) over the Sn‐Beta catalyst was found to be a highly efficient process for producing lactic acid as a platform ...chemical. One‐pot reaction with a very high lactic acid yield of 83.0 % was realized in a batch reactor using water as the solvent. Under the attack of formic acid, the cell wall of Scenedesmus was disintegrated, and hydrolysis of the starch inside the cell was strengthened in a controlled‐release mode, resulting in a stable and relatively low glucose concentration. Subsequently, the Sn‐Beta catalyst was employed for the efficient conversion of glucose into lactic acid with stable catalytic performance through isomerization, retro‐aldol and de‐/rehydration reactions. Thus, the hydrolysis of polysaccharides and the catalytic conversion of the monosaccharide into lactic acid was realized by the combination of an organic Brønsted acid and a heterogeneous Lewis acid catalyst.
Hey Scenesters! Formic acid‐induced controlled‐release one‐pot hydrolysis of microalgae (Scenedesmus) over Sn‐Beta catalyst was developed to afford lactic acid in an excellent product of 83.0 % in water. The hydrolysis of polysaccharides and the catalytic conversion of monosaccharide into lactic acid were realized by the combination of a Brønsted acid catalyst and a heterogeneous Lewis acid catalyst.
The critical problem facing Ni‐based catalysts for the CO2 reforming of methane (DRM) is the serious carbon deposition and metal sintering, which are sensitive to the size of Ni particles. A ...perovskite‐type catalyst La0.46Sr0.34Ti0.9Ni0.1O3 (denoted as LSTN0.1) with a bimodal size distribution of Ni particles was prepared by combustion method. Under mild DRM conditions (CH4:CO2=1:1.2 at 700 °C), no coke was found on LSTN0.1 after 100 h reaction, and the comparison with the impregnated catalysts showed that the carbon resistance is closely associated with the strong metal–support interaction and basicity. Nevertheless, under harsh reaction conditions (CH4:CO2=2:1 at 700 °C), the coking process speeded up on LSTN0.1. This bimodal Ni catalyst had higher coke resistance than the catalyst possessing few small particles. Moreover, the coke was found on the large Ni particles (14.5 nm average size) but the small Ni particles (2.5 nm average size) remained unchanged.
The perovskite‐type catalyst LSTN0.1 with a bimodal size distribution of Ni particles showed excellent resistance to carbon deposition, which is due to the strong metal–support interaction and basicity. The faster reaction rate and the higher coke resistance of the small Ni particles means that the amount of deposited carbon is less than that for large Ni particles only.
Particle size effects of the cobalt carbide (Co2C) catalyst on its catalytic performance for Fischer–Tropsch to olefins were investigated. When the Co2C nanoparticles were smaller than 7 nm, ...increasing the particle size led to enhanced intrinsic activity based on the turnover frequency (TOF), higher selectivity to lower olefins, higher ratio of olefin to paraffin, and lower methane selectivity. However, when the Co2C nanoparticles were larger than 7 nm, both intrinsic activity and product selectivity did not depend on the particle size. Further kinetic studies showed that both the apparent activation energy and the reaction order of H2 decreased, while the reaction order of CO increased with decreasing Co2C particle size when the size was smaller than 7 nm. In contrast, these kinetic parameters were nearly constant when the Co2C particle size was larger than 7 nm. Theoretical analysis revealed a strong correlation between the exposed facets and Co2C particle sizes, leading to the observed dependence of catalytic performance on the catalyst particle size.
Display omitted
•The morphologies of pyrite can be divided into three types, and pyrite genesis involves TSR and BSR.•The TSR reaction is caused by the rapid subsidence of the basin resulting in an ...increase of the temperature of the basinal fluids.•Pyrite formed by TSR has provided the metals incorporated thereafter into biogenic pyrite during BSR.•Uranium mineralization occurs during the regional uplift associated with a decrease of the geothermal temperature and is therefore closely related to pyrite formed by BSR.
Combined microstructural, isotopic and chemical analysis of pyrite reveals the complexity of its genesis from the Jurassic Zhiluo Formation in the Diantou-Shuanglong sandstone-hosted uranium deposit, southern Ordos Basin. Framboidal, euhedral-subhedral and cement pyrite are identified by optical microscope and scanning electron microscope (SEM). Among them, euhedral-subhedral pyrite occurs in two forms, either as an independent mineral or wrapped by another phase of pyrite, where the wrapped euhedral core is designated as Py1, and another phase of pyrite named Py2 rims Py1. Sulfur isotope of pyrite by secondary ion mass spectrometry (SIMS) shows that each pyrite has a distinct composition (−30.64 ‰ to −17.94 ‰ for independent euhedral pyrite, −25.19 ‰ to +19.55 ‰ for cement pyrite, −4.79 to +3.73 ‰ for Py1, −24.27 to −10.15 ‰ for Py2). Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to reveal a considerable range of trace element compositions for different types of pyrite. The concentrated distribution of sulfur isotope values and the enrichment of trace element (Co, Tl, Sb, etc.) in Py1 indicate that it was formed by thermochemical sulfate reduction (TSR). Combined with relatively stable structures and absence of magmatic hydrothermal activity in the Ordos Basin, we propose that the rapid subsidence of the southern Ordos Basin in the Early Cretaceous led to increase of the basinal fluids temperature which reached the threshold temperature of TSR and formation of abiogenic pyrite. The negative sulfur isotope values and trace element depletion of other types of pyrite indicate that they were formed by bacterial sulfate reduction (BSR). Some cement pyrites show positive δ34S due to Rayleigh isotope fractionation. Although the negative sulfur isotope values of Py2 indicates biogenesis, it contains relatively high trace element compared to other biogenic pyrite. At the end of the subsequent Early Cretaceous, uplift and denudation of the basin led to a decrease in geothermal gradient. Simultaneously, the Zhiluo Formation was exposed to the surface and received uranium-bearing oxidized fluids, indicating the beginning of uranium mineralization. Py1 of pre-ore pyrite was dissolved to form growth textures and release trace element during the infiltration of uranium-bearing oxidized fluids, and Py2 formed by the BSR has precipitated from trace element enriched fluids, resulting in moderately high trace element content and lighter sulfur isotope values. Therefore, uranium minerals precipitate around biogenic pyrite or between Py1 and Py2. We suggest that abiogenic redox processes and biogenic activities are involved in pyrite mineralization, which together promote uranium precipitation. This proposition is helpful for further understanding the mechanism of pyritization and uranium mineralization, and provides valuable guidance for thermogenic interpretation of other sedimentary basins with similar stable structures.
The direct synthesis of cyclic carbonates through oxidative carboxylation of alkenes using CO
and O
offers a sustainable and carbon-neutral method for CO
utilization, which is, however, still a ...largely unexplored field. Here we develop a single-atom catalyst (SAC) Co-N/O-C as the earth-abundant metal catalyst for the oxidative carboxylation of styrene with CO
and O
. Remarkably, even using the flue gas as an impure CO
and O
source, desired cyclic carbonate could be obtained with moderate productivity, which shows the potential for integrated CO
capture and conversion, leveraging the high CO
adsorption capacity of Co-N/O-C. In addition, the catalyst can be reused five times without an obvious decline in activity. Detailed characterizations and theoretical calculations elucidate the crucial role of single Co atoms in activating O
and CO
, as well as controlling selectivity.
The direct synthesis of cyclic carbonates through oxidative carboxylation of alkenes using CO2 and O2 offers a sustainable and carbon‐neutral method for CO2 utilization, which is, however, still a ...largely unexplored field. Here we develop a single‐atom catalyst (SAC) Co−N/O−C as the earth‐abundant metal catalyst for the oxidative carboxylation of styrene with CO2 and O2. Remarkably, even using the flue gas as an impure CO2 and O2 source, desired cyclic carbonate could be obtained with moderate productivity, which shows the potential for integrated CO2 capture and conversion, leveraging the high CO2 adsorption capacity of Co−N/O−C. In addition, the catalyst can be reused five times without an obvious decline in activity. Detailed characterizations and theoretical calculations elucidate the crucial role of single Co atoms in activating O2 and CO2, as well as controlling selectivity.
The oxidative carboxylation of styrene with CO2 and O2 even flue gas has been realized using single atom catalyst Co−N/O−C.
Single atom catalysts (SACs) are receiving increasing interests due to their high theoretical catalytic efficiency and intriguing physiochemical properties. However, most of the synthetic ...methodologies involve high‐temperature treatment. This usually leads to limited control over the spatial distribution of metal sites and collapse of porous network that result in limited active site exposure. A strategy to construct SAC by using a covalent organic framework as the precursor is reported in this study. The as‐prepared catalyst is mainly composed of standing carbon layers with the presence of edge‐site hosted metal single atoms. Such structure configuration not only allows full site exposure but also endows the metal site with high intrinsic activity. With a trace amount of cobalt loading (0.17 wt%), the nanorice‐shaped catalyst displays promising electrochemical activities toward catalyzing the oxygen reduction reaction in both alkaline and acidic medium. An ultrahigh mass activity of 838 A gCo–1 at 0.9 V is achieved in the acidic electrolyte. This work suggests a new route to design SACs based on covalent organic framework for energy storage and conversion devices.
A Co single atom catalyst supported by standing carbon derived from covalent organic framework is reported. The catalyst displays promising oxygen reduction reaction (ORR) activity in both alkaline and acidic medium. The ORR activity in the acidic medium mainly originates from the edge Co‐Nx sites that are fully exposed to the reactants. The mass activity reaches as high as 838 A gCo–1.
Nitrogen-doped carbons were produced using hydrothermal carbonization of nitrogen-containing carbohydrates under mild temperature (180
°C). The resulting materials contain significant amounts of ...nitrogen and display a high degree of aromatization. The nitrogen contents are also retained after further calcination at higher temperatures. All the resulting materials have been thoroughly characterized using X-ray photoelectron spectroscopy, solid state
15N and
13C-nuclear magnetic resonance, elemental chemical analysis, nitrogen adsorption, scanning and transmission electron microscopy. The nitrogen-doped materials proved to have superior performance with respect to their nitrogen-free counterparts in terms of electrical conductivity.
PDF