C, N, and P Stoichiometry Characteristics of Fresh and Weathered Sandstones in Longhushan Area, SE China

Altres ajuts: the Fundación Ramón Areces grant CIVP20A6621Carbon (C), nitrogen (N), and phosphorus (P) stoichiometry and their allometric relationships in soil and plants are hot topics that attract a lot of attention, while those rocks that form soils are often neglected. Weathering is a common geological phenomenon that may significantly influence the nutrient composition and release of nutrients from rock and its inherent soils. This study presents C, N, and P concentrations data as well as microscope petrological photographs of fresh and weathered sandstones from Longhushan World Geopark in SE China, in an attempt to investigate C, N, and P stoichiometry of rocks before and after weathering and discuss the driving mechanisms. The results show that weathering significantly decreased rock C, C/N, and C/P concentrations, slightly decreased N and N/P concentrations, and slightly increased P concentration. Microscope observations show that fresh sandstones contain calcite, apatite, microplagioclase, and organic matter, while weathered sandstones feature apatite and organic matter. The flexible allometric relationships and mineral changes before and after rock weathering indicate that chemical mechanisms, such as dissolution of carbonate and hydration of microplagioclase, have changed the existence form of C, N, P and, thus, significantly influence rock C, N, and P stoichiometry. This stoichiometry feature can be in turn used to reflect the regulation effect of rock weathering

Distribution Behavior of Impurities during the Hydrogen Reduction Ironmaking Process

The traditional blast furnace ironmaking process is the most widely used ironmaking process globally, yet it is associated with significant drawbacks, including high energy consumption and carbon emissions. To achieve low-carbon ironmaking, researchers have developed hydrogen ironmaking, which is capable of achieving lower CO2 emissions. Nevertheless, the distribution behavior of impurities has been less studied in the existing research on hydrogen ironmaking. Therefore, in this study, the factors affecting the slag properties and distribution of impurity elements during hydrogen ironmaking were investigated using FactSage, and smelting experiments were carried out. The results show that temperature has the greatest influence on the distribution behavior of the impurities, and excessively elevated temperatures result in the ingress of a significant quantity of impurities into the reduced iron. Reduced iron with a purity of 98.52% was obtained under the conditions of 10%, 10%, 2%, and 2% ratios of CaO, SiO2, MgO, and Al2O3, respectively, a hydrogen flow rate of 12 mL/min, and a temperature of 1400 °C; Lg L Mg, Lg L Al, Lg L Si, and Lg L Ca were 2.72, 2.41, 3.36, and 2.45, respectively (“L” stands for slag-to-metal ratio). The slag was mainly dominated by the silicate, and the iron was mainly lost in the form of mechanical inclusions in the slag. This study will enrich the basic theory of hydrogen ironmaking and is of great significance for the realization of carbon neutralization

Research on Soft Rock Damage Softening Model and Roadway Deformation and Failure Characteristics

To determine a reasonable control strategy for deep buried soft rock roadways, a study on deformation and failure characteristics was carried out. The Weibull distribution damage variable was introduced to construct a damage-softening model considering the lateral deformation of the rock mass, and the functional relationship between the model parameters F0 and m and the confining pressure were discussed. The nonlinear fitting method was used to correct the model parameters. Using the model, the failure characteristics of deep buried soft rock roadways were analyzed. A comprehensive and step-by-step joint support control strategy was proposed based on the numerical simulation results. The research results showed that the damage-softening model curve established could genuinely reflect the whole process of mudstone failure. The apparent stress concentration phenomenon occurred in the surrounding rock. The surrounding rock deformation showed that roadway floors had larger plastic failure areas than sides and vaults. The plastic failure depth could reach 2.45 m. After a comprehensive and step-by-step joint support control strategy was adopted, the deformation rate of the roadway at the section was less than 0.1 mm/d. The optimized support scheme can effectively improve the stability of the roadway

Porous polyaniline/carbon nanotube composite electrode for supercapacitors with outstanding rate capability and cyclic stability

Polyaniline (PANI) is one of the most widely used organic electrode materials for supercapacitors. It has advantages such as good environmental stability and low cost, whereas it is difficult to achieve high capacitance, good rate capability and long cycle life simultaneously. In this work, a series of porous polyaniline/carbon nanotube (PANI/CNT) composite materials are prepared by chemically grafting PANI on CNTs and creating interpenetrating pores via templating using CaCO₃ nanoparticles, and then studied as electrode materials for supercapacitors. As PANI is covalently grafted on CNT networks formed in the electrode, the delocalization of electrons improves electron transport in the electrode and the stability of PANI in redox cycling process. The porous morphology created provides sufficient channels for the transport of ions. As a result, the optimized PANI/CNT composite exhibits a high capacitance of 1266 F g⁻¹ at a specific current of 1 A g⁻¹, and even at a specific current of 128 A g⁻¹ the specific capacitance could reach 864 F g⁻¹. Moreover, after cycling tests of 10,000 cycles, it remains 83% of its capacitance at the first cycle. The excellent rate performance and cycle stability of the porous PANI/CNT composite makes it a promising high-performance electrode material for supercapacitors

Modulating the strong metal-support interaction of single-atom catalysts via vicinal structure decoration

A simple water soaking treatment significantly weakened the strong covalent metal-support interaction between the atomically dispersed Pt and CoFe2O4, which leads to an enhanced activity towards methane combustions by 55 times. This work highlights the critical role of altering the coordination structure of single-atom active sites and provides a new strategy to modulate metal-support interaction regulation

Suppression of local invasion of ameloblastoma by inhibition of matrix metalloproteinase-2 in vitro-3

Der phase-contrast microscopy (× 100). (B) Sub-cultured ameloblastoma cells had vigorous growth in 2–4 passages. Cells were large and flattened or spindle-shaped under phase-contrast microscopy (× 200). (C) Immunocytochemistry confirmed the epithelial origin of the ameloblastoma cells based on cytokeratin 14 and 16 expression; cytokeratin 18 and vimentin were only weakly expressed (× 300). (D) Immunofluorescence for MMP-2 in ameloblastoma cells. Cells were examined and photographed under fluorescent microscopy. The green fluorescence shows the localization of MMP-2 and nuclei were counterstained with propidium iodine (PI) which fluoresced red (× 300).<p><b>Copyright information:</b></p><p>Taken from "Suppression of local invasion of ameloblastoma by inhibition of matrix metalloproteinase-2 in vitro"</p><p>http://www.biomedcentral.com/1471-2407/8/182</p><p>BMC Cancer 2008;8():182-182.</p><p>Published online 30 Jun 2008</p><p>PMCID:PMC2443806.</p><p></p