The propagation process of blasting vibration has always been a difficult problem affecting the stability of high slopes in open-pit mines. Taking the Jianshan Phosphorus Mine as the research ...background, combined with engineering geological investigation, field blasting test, blasting vibration monitoring, numerical simulation technology, and theoretical analysis, the three-dimensional dynamic stability of the adjacent high slope after blasting vibration was systematically studied. In our study, a small-diameter buffer shock-absorbing blasting technology near the slope was proposed, which greatly improved the production efficiency. Through regression analysis of a large amount of vibration test data, the law of blasting vibration propagation in Jianshan stope and Haifeng stope was obtained. In addition, by establishing four three-dimensional geomechanical numerical models, the slope's own frequency, damping characteristics, and dynamic response acceleration distribution after detonation were studied, respectively. On the other hand, under the action of Ei Centro wave with 8-degree seismic intensity, the maximum total acceleration and maximum total displacement of the slope were calculated and analyzed. Both the explosion unloading of the 8-degree earthquake and the Ei Centro wave simulation results showed that the high slope near the Jianshan Phosphorus Mine was generally in a stable state. Thus, this study can provide technical support and theoretical guidance for mine blasting.
Ferroptosis is a form of necrotic cell death caused by iron-dependent peroxidation of polyunsaturated phospholipids on cell membranes and is actively suppressed by the cellular antioxidant systems. ...We report here that oxidoreductases, including NADPH-cytochrome P450 reductase (POR) and NADH-cytochrome b5 reductase (CYB5R1), transfer electrons from NAD(P)H to oxygen to generate hydrogen peroxide, which subsequently reacts with iron to generate reactive hydroxyl radicals for the peroxidation of the polyunsaturated fatty acid (PUFA) chains of membrane phospholipids, thereby disrupting membrane integrity during ferroptosis. Genetic knockout of POR and CYB5R1 decreases cellular hydrogen peroxide generation, preventing lipid peroxidation and ferroptosis. Moreover, POR knockdown in mouse liver prevents ConA-induced liver damage. Ferroptosis, therefore, is a result of incidental electron transfer carried out by POR/CYB5R1 oxidoreductase and thus needs to be constitutively countered by the antioxidant systems.
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•The oxidoreductases POR and CYB5R1 are required for ferroptosis•POR and CYB5R1 produce H2O2 to initiate iron-dependent Fenton reaction•POR and CYB5R1 induce lipid peroxidation and membrane rupture in liposomes•Knockdown of POR in vivo protects ConA-induced ferroptotic liver damage
Yan et al. found that, during ferroptosis, the oxidoreductases POR and CYB5R1 transfer electrons from NAD(P)H to oxygen to generate H2O2, which reacts with iron to produce hydroxyl radials for peroxidation of PUFA-containing membrane phospholipids to cause membrane damage and necrotic cell death.
Hydrophilic interaction liquid chromatography (HILIC) is a significant enrichment strategy in glycoproteomics profiling. In this report, hydrophilic magnetic mesoporous silica materials (denoted as ...Fe3O4@mSiO2-IDA) were designed and synthesized as an outstanding enrichment platform for glycopeptide analysis. By taking advantage of their merits, such as large surface area, excellent hydrophilicity and unbiased affinity toward all types of glycopeptides, the Fe3O4@mSiO2-IDA nanomaterials were successfully applied to capture glycopeptides from complex samples. A total of 25 glycopeptides from horseradish peroxidase (HRP) digests and 33 glycopeptides from IgG were identified, respectively. Especially, as a result, 424 glycopeptides assigned to 140 glycoproteins were identified from only 2 μL human serum.
Visible‐light‐driven conversion of CO2 into chemical fuels is an intriguing approach to address the energy and environmental challenges. In principle, light harvesting and catalytic reactions can be ...both optimized by combining the merits of homogeneous and heterogeneous photocatalysts; however, the efficiency of charge transfer between light absorbers and catalytic sites is often too low to limit the overall photocatalytic performance. In this communication, it is reported that the single‐atom Co sites coordinated on the partially oxidized graphene nanosheets can serve as a highly active and durable heterogeneous catalyst for CO2 conversion, wherein the graphene bridges homogeneous light absorbers with single‐atom catalytic sites for the efficient transfer of photoexcited electrons. As a result, the turnover number for CO production reaches a high value of 678 with an unprecedented turnover frequency of 3.77 min−1, superior to those obtained with the state‐of‐the‐art heterogeneous photocatalysts. This work provides fresh insights into the design of catalytic sites toward photocatalytic CO2 conversion from the angle of single‐atom catalysis and highlights the role of charge kinetics in bridging the gap between heterogeneous and homogeneous photocatalysts.
Single‐atom Co sites coordinated on partially oxidized graphene nanosheets can serve as a highly active and durable heterogeneous catalyst for CO2 conversion, wherein the graphene bridges homogeneous light absorbers with single‐atom catalytic sites for the efficient transfer of photoexcited electrons. This design enables a turnover frequency of 3.77 min−1, superior to those obtained with conventional heterogeneous photocatalysts.
An excited-state thermometer was designed based on the difference in thermal change tendency of the excitation bands in double-perovskite La2ZnTiO6: Tb3+ phosphor. The temperature dependent ...excitation spectra monitored at Tb3+ 543 nm emission revealed that the 4f8→4f75d and Tb3+–Ti4+ intervalence charge transfer (IVCT) excitation bands descended faster with rising temperature in contrast to the case of 4f–4f excitation peaks. The primary cause was analyzed by considering the relationship between the depopulating process and excitation wavelength. Moreover, the excitation intensity ratio of 7F6→5D3 versus IVCT can be used for thermometry with maximal absolute and relative sensing sensitivities of ∼4.46 × 10−2 K−1 and 0.727% K−1, indicating the potential for temperature sensing applications.
•Thermal quenching rates of Tb3+ emissions in La2ZnTiO6 alter with excitation lines.•Thermal stability of 4f-4f excitation peaks is better than that of 4f.→5d and IVCT ones.•Excitation intensity ratio of 7F6.→5D3 to IVCT (or 4f→5d) can be applied for sensing.
Acyclic quaternary stereocenters are widely present in a series of biologically active natural products and pharmaceuticals. However, development of highly efficient asymmetric catalytic methods for ...the construction of these privileged motifs represents a longstanding challenge in organic synthesis. Herein, an efficient chiral phosphoric acid catalyzed direct asymmetric addition of α-alkynyl acyclic ketones with allenamides has been developed, furnishing the acyclic all-carbon quaternary stereocenters with excellent regioselectivities and high enantioselectivities. Extensive and detailed experimental mechanistic studies were performed to investigate the mechanism of this reaction. Despite a novel covalent allyl phosphate intermediate was found in these reactions, further studies indicated that a S
2-type mechanism with the ketone nucleophiles is not very possible. Instead, a more plausible mechanism involving the elimination of the allyl phosphate to give the α,β-unsaturated iminium intermediate, which underwent the asymmetric conjugate addition with the enol form of ketone nucleophiles under chiral anion catalysis, was proposed. In virtue of the fruitful functional groups bearing in the chiral products, the diverse derivatizations of the chiral products provided access to a wide array of chiral scaffolds with quaternary stereocenters.
Complete ammonia oxidizing bacteria (CAOB) have been recognized as a new member of ammonia-oxidizing microorganisms (AOMs) due to its single-step nitrification capability. However, the abundance and ...diversity of CAOB in environmental ecosystems were still far from known owing to the lack of specific molecular marker. Herein, a universal primer set specifically targeting both clades of CAOB amoA gene with high specificity and coverage was successfully designed. Intriguingly, real-time quantitative PCR tests revealed that CAOB were ubiquitous and unexpectedly abundant in agricultural soils, river sediments, intertidal zones, drinking water and wastewater treatment systems. Phylogenetic analysis indicated that clade A existed in all the five types of ecosystems, while clade B were only detected in soil and sediment samples. Four sub-clusters were further classified within clade A, in which N. nitrosa cluster dominated CAOB amoA in activated sludge samples while the new recognized soil cluster was the primary constitute in soils. Moreover, the niche specialization between different CAOB species and the environmental conditions were supposed to be the primary driven force to shape the diversity and community of CAOB. This study provided a strong evidence in support of the ubiquities and high abundances of CAOB in various environmental ecosystems and highlighted the significance of including CAOB as the new member of AOMs to re-evaluate the biogeochemical nitrogen cycle.
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•A universal primer specifically targeting both clades of CAOB amoA was developed.•Ubiquities and high abundances of CAOB in five environmental samples were revealed.•Clade A and B showed distinct phylogenetic distribution among different ecosystems.•It is significant to re-evaluate the nitrogen cycle by including CAOB as a new AOM.
The recent discovery of comammox Nitrospira as complete nitrifiers has fundamentally renewed perceptions of nitrogen cycling in natural and engineered systems, yet little is known about the ...environmental controls on these newly recognized bacteria. Based on improved phylogenetic resolution through successful assembly of ten novel genomes (71-96% completeness), we provided the first biogeographic patterns for planktonic and benthic comammox Nitrospira in the Yangtze River over a 6030 km continuum. Our study revealed the widespread distributions and relative abundance of comammox Nitrospira in this large freshwater system, constituting 30 and 46% of ammonia-oxidizing prokaryotes (AOPs) and displaying 30.4- and 17.9-fold greater abundances than canonical Nitrospira representatives in water and sediments, respectively. Comammox Nitrospira contributed more to nitrifier abundances (34-87% of AOPs) in typical oligotrophic environments with a higher pH and lower temperature, particularly in the plateau (clade B), mountain and foothill (clade A) areas of the upper reach. The dominant position of planktonic comammox Nitrospira was replaced by canonical Nitrospira sublineages I/II and ammonia-oxidizing bacteria from the plateau to downstream plain due to environmental selection, while the dissimilarity of benthic comammox Nitrospira was moderately associated with geographic distance. A substantial decrease (83%) in benthic comammox Nitrospira abundance occurred immediately downstream of the Three Gorges Dam, consistent with a similarly considerable decrease in overall sediment bacterial taxa. Together, this study highlights the previously unrecognized dominance of comammox Nitrospira in major river systems and underlines the importance of revisiting the distributions of and controls on nitrification processes within global freshwater environments.
The skin serves as a physical barrier and an immunological interface that protects the body from the external environment
. Aberrant activation of immune cells can induce common skin autoimmune ...diseases such as vitiligo, which are often characterized by bilateral symmetric lesions in certain anatomic regions of the body
. Understanding what orchestrates the activities of cutaneous immune cells at an organ level is necessary for the treatment of autoimmune diseases. Here we identify subsets of dermal fibroblasts that are responsible for driving patterned autoimmune activity, by using a robust mouse model of vitiligo that is based on the activation of endogenous auto-reactive CD8
T cells that target epidermal melanocytes. Using a combination of single-cell analysis of skin samples from patients with vitiligo, cell-type-specific genetic knockouts and engraftment experiments, we find that among multiple interferon-γ (IFNγ)-responsive cell types in vitiligo-affected skin, dermal fibroblasts are uniquely required to recruit and activate CD8
cytotoxic T cells through secreted chemokines. Anatomically distinct human dermal fibroblasts exhibit intrinsic differences in the expression of chemokines in response to IFNγ. In mouse models of vitiligo, regional IFNγ-resistant fibroblasts determine the autoimmune pattern of depigmentation in the skin. Our study identifies anatomically distinct fibroblasts with permissive or repressive IFNγ responses as the key determinant of body-level patterns of lesions in vitiligo, and highlights mesenchymal subpopulations as therapeutic targets for treating autoimmune diseases.
Dynamic recrystallization (DRX) refine grains of high entropy alloys (HEAs) and significant improve the mechanical property of HEAs, but the effect of high melting point element molybdenum (Mo) on ...high temperature deformation behavior has not been fully understood. In the present study, flow behavior and microstructures of powder metallurgical CrFeCoNiMo0.2 HEA were investigated by hot compression tests performed at temperatures ranging from 700 to 1100°C with strain rates from 10−3 to 1s−1. The Arrhenius constitutive equation with strain-dependent material constants was used for modeling and prediction of flow stress. It was found that at 700°C, the dynamic recovery is the dominant softening mechanism, whilst with the increase in compression testing temperature, the DRX becomes the dominant mechanism of softening. In the present HEA, the addition of Mo results in the high activation energy (463kJmol−1) and the phase separation during hot deformation. The formation of Mo-rich σ phase particles pins grain boundary migration during DRX, and therefore refines the size of recrystallized grains.
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