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Two-dimensional material-supported single metal atom catalysts have been extensively studied and proved effective in electrocatalytic reactions in recent years. In this work, we systematically investigate the OER catalytic properties of single metal atoms supported by the NiN2 monolayer. Several typical transition metals with high single atom catalytic activity, such as Fe, Co, Ru, Rh, Pd, Ir, and Pt, were selected as catalytic active sites. The energy calculations show that transition metal atoms (Fe, Co, Ru, Rh, Pd, Ir, and Pt) are easily embedded in the NiN2 monolayer with Ni vacancies due to the negative binding energy. The calculated OER overpotentials of Fe, Co, Ru, Rh, Pd, Ir and Pt embedded NiN2 monolayers are 0.92 V, 0.47 V, 1.13 V, 0.66 V, 1.25 V, 0.28 V, and 0.94 V, respectively. Compared to the 0.57 V OER overpotential of typical OER noble metal catalysts IrO2, Co@NiN2 and Ir@NiN2 exhibit high OER catalytic activity due to lower overpotential, especially for Ir@NiN2. The high catalytic activity of the Ir embedded NiN2 monolayer can be explained well by the d-band center model. It is found that the adsorption strength of the embedded TM atoms with intermediates follows a linear relationship with their d-band centers. Besides, the overpotential of the Ir embedded NiN2 monolayer can be further reduced to 0.24 V under −2% biaxial strain. Such findings are expected to be employed in more two-dimensional material-supported single metal atom catalyzed reactions. [ABSTRACT FROM AUTHOR]

Root biomass and length growth, functional traits, and their responses to soil nutrient availability are crucial for resource acquisition under environmental change. Previous studies have focused on the response of root morphological, architectural, and chemical traits to fertilization, while less attention has been given to root biomass and length growth, as well as mycorrhizal symbiosis, impeding a full understanding of root resource acquisition strategies. Here, using a nutrient addition experiment (control, inorganic, and organic nutrients), we explored the responses of function-based root (absorptive fine roots [AFRs] versus transport fine roots [TFRs]) growth, functional traits (morphological, architectural, and chemical traits), and mycorrhizal colonization of C. lanceolat and Q. acutissim, which are the dominant tree species in subtropical China. The results showed that the fine root biomass and total root length of AFRs for both tree species basically decreased significantly after nutrient addition, but TFRs responded less sensitively than AFRs. Nutrient addition significantly increased the mycorrhizal colonization rate in C. lanceolata but decreased it in Q. acutissima. The diameter of AFRs for C. lanceolata increased significantly, while the branch ratio and branch intensity decreased significantly in both inorganic nutrients (NPK) and organic nutrients (F); however, the opposite response pattern occurred for Q. acutissima. Fine root biomass, total root length, and root nutrient concentration exhibited the most plastic responses to changes in nutrient availability. The magnitude of the plastic response of fine root traits was slightly higher in the NPK treatment than in the F treatment. Our findings suggest that the responses of fine root traits and mycorrhizal fungi to nutrient addition were species-specific: C. lanceolata depended on mycorrhizal fungi for resource acquisition, while Q. acutissima could acquire soil nutrient resources by increasing root branching. The contrasting nutrient acquisition strategies between tree species may facilitate plant species coexistence and distribution under soil nutrient change. Fine root biomass and total root length emerged as more pivotal indicators for nutrient acquisition strategies compared to morphological traits. [ABSTRACT FROM AUTHOR]

Forming ohmic contacts between metals and semiconductors is critical to achieving high-performance and energy-efficient electronics. Here we investigate the interface properties of WSi2N4 contacted by Mo2B, O-modified Mo2B (Mo2BO2) and OH-modified Mo2B (Mo2B(OH)2) nanosheets using density functional theory simulations. We show that WSi2N4 and Mo2B form n-type Schottky contacts with barrier heights that are robust against external electric fields. In contrast, functionalizing Mo2B with O and OH causes the work function to energetically down- and up-shift significantly, thus forming both n-type and p-type ohmic contacts with WSi2N4, respectively. The possibility of achieving both p-type and n-type ohmic contacts immediately suggests the role of surface-engineered Mo2B as a key enabler towards WSi2N4-based complementary metal–oxide–semiconductor (CMOS) device technology in which both n-type and p-type devices are needed. We further demonstrate the emergence of quasi-ohmic contact with ultralow lateral Schottky barrier and zero vertical interfacial tunneling barriers in Mo2B(OH)2-contacted WSi2N4 – a feature rarely found in other 2D/2D metal/semiconductor contacts, thus demonstrating surface-engineered Mo2B as a promising electrode to WSi2N4 with high charge injection efficiency. These results offer design insights useful for the development of high-performance 2D semiconductor CMOS device technology. [ABSTRACT FROM AUTHOR]

There is increasing evidence that Chronic Kidney Disease (CKD) can cause intestinal dysfunction, which in turn aggravates the progression of kidney disease. Studies have shown that the immune response of macrophage plays an important role in promoting inflammation in kidney and intestine of CKD. Astragalus mongholicus Bunge and Panax notoginseng formula (A&P) is a widely used traditional medicine for the treatment of CKD in China, however, the underlying mechanism is largely unclear. In this study, we aimed to explore the role of A&P and Bifidobacterium combination treatment in regulation of inflammatory response of macrophage in kidney and intestine of CKD mouse, as well as the potential molecular mechanism. We established a CKD mouse model with 5/6 nephrectomy and a macrophage inflammatory cellular model with LPS and urotoxin in vivo and in vitro. The results showed that A&P combined with Bifidobacterium significantly reduced the expression and secretion of IL-1β, IL-6, TNFα, and MCP-1 in kidney and blood, as well as in inflammatory macrophage. Interestingly, A&P combined with Bifidobacterium strongly improved the intestinal flora and protected the intestinal barrier. Notably, the maintainer of macrophage polarization, Mincle, was activated in kidney and intestine of CKD mouse as well as in urotoxin stimulated macrophage, that was effectively inhibited by the treatment of A&P and Bifidobacterium combination. Overexpression of Mincle by genetic modification can abolish the inhibitory effects of A&P combined with Bifidobacterium on inflammation in urotoxin stimulated RAW264.7 cells. In summary, these findings demonstrated that A&P combined with Bifidobacterium can protect kidney against CKD by down-regulating macrophage inflammatory response in kidney and intestine via suppressing Mincle signaling, which provides a new insight in the treatment of CKD with traditional medicine.