Search

• Soil microbes were co-limited by the C and P during oak forest restoration, but these limitations tended to decrease gradually. • Rhizosphere soil microorganisms were subject to relatively strong C limitation and weak P limitation compared with those in bulk soil. • Microbial C and P limitation in the rhizosphere soil were mainly dependent on the DOC and Olsen−P. • An increase in the soil water content decreased the relative P limitation for the rhizosphere microbial community. Microbial metabolism changes in soil systems along a vegetation restoration gradient have attracted considerable attention; however, the differences in microbial metabolic limitations between the rhizosphere and bulk soil and their drivers during natural secondary forest restoration after disturbance have rarely been investigated. Here, we used multiple methods based on extracellular enzymatic stoichiometry to examine the microbial metabolic limitations in the rhizosphere and bulk soils along with a clear-cut oak (Quercus aliena var. acuteserrata) forest restoration over 58 years in the Qinling Mountains, China. Overall, the microbial metabolisms in both rhizosphere and bulk soils were co-limited by the availability of soil carbon (C) and phosphorus (P), and the limitations tended to decrease during restoration. Rhizosphere soil microorganisms were subject to relatively strong C limitation and weak P limitation compared with those in bulk soil. Microbial C and P limitations in the bulk soil were regulated by the nutrient ratios, and those in the rhizosphere soil were mainly dependent on the available nutrients mediated by soil moisture. Our results indicate that variations in the soil nutrients caused by oak forest restoration and water differences caused by the rhizosphere effect regulated microbial C and P metabolism in the rhizosphere and bulk soils. This study highlights the microbial metabolism difference between rhizosphere and bulk soil and its drivers during oak forest restoration and provides insights into the microbial resource limitation, nutrient cycling, and rhizosphere processes in the natural secondary forests after clear-cutting. [ABSTRACT FROM AUTHOR]

This study investigates the mixing processes of liquid jets in supersonic crossflows at a Mach number of 2.1 by using numerical simulations that employ the Coupled Level-Set/Volume-of-Fluid (CLSVOF) method, which is based on the Delayed Detached Eddy Simulation (DDES). The instantaneous spray morphology from the simulations agreed well with the experimental data. The spray presents the 'Ω' shape when viewed from the front, and the maximum error in the penetration depth was 15% from a side perspective. The direction of the air movement determined the shape of the liquid column shearing and breaking. In turn, the breaking process of the liquid jet significantly affects the structure of the air flow. Three-dimensional flow around the liquid column occurred when the supersonic incoming flow impinged on the liquid column, ultimately forming counter-rotating vortex pairs (CVP) in the inner region of the spray. Evolution of the reverse vortex pair accelerated the mixing process of the spray. Single liquid jet was used as a basis to further study double jets in Mach 2.1 airflow. The results show that the breaking length and penetration depth of the downstream jet are significantly improved. [ABSTRACT FROM AUTHOR]

To obtain the mixing enhancement mechanism of H 2 –Water combined jets in supersonic crossflows in a combustor with expanded section for rotating detonation ramjet, the flow field shape and spray structure were studied by experimental and numerical methods. The Eulerian–Lagrangian method was used to investigate the diffusion mechanism and H 2 –Water interaction law of combined jets with different sequences. At the same time, high-speed photography and the schlieren technique were used to capture the flow field. The effects of jet pressure drop, orifice diameter, orifice spacing, incoming Mach number, and other parameters on the penetration depth of water jets were studied. The results of experiment and simulation show that using H 2 –Water combined jets, the penetration depth of the jet spray can be greatly increased and the jet mixing effect can be significantly improved, which will contribute to the engine's ignition and stable combustion. In the case of pre-water/post-H 2 , the penetration depth of the hydrogen jet is greater. In the case of pre-H 2 /post-water, the hydrogen jet raises the water spray mainly by protecting the integrity of the water column. • The mechanism of the mixing process of H2-Water combined jets in supersonic crossflows was investigated. • Eulerian-Lagrangian method was used to investigate the H2-Water interaction law in a combustor with an expanded section. • The penetration depth of water jets under different parameters was studied experimentally. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Novel technetium-labeled ligands, 99mTc-NCAM and 99mTc-NHAM were developed from the N-methyl-d-aspartate (NMDA) receptor agonist memantine as a lead compound by coupling with N2S2. This study evaluated the binding affinity and specificity of the ligands for the NMDA receptor. Methods: Ligand biodistribution and uptake specificity in the brain were investigated in mice. Binding affinity and specificity were determined by radioligand receptor binding assay. Three antagonists were used for competitive binding analysis. In addition, uptake of the complexes into SH-SY5Y nerve cells was evaluated. Results: The radiochemical purity of 99mTc-labeled ligands was more than 95%. Analysis of brain regional uptake showed higher concentration in the frontal lobe and specific uptake in the hippocampus. 99mTc-NCAM reached a higher target to nontarget ratio than 99mTc-NHAM. The results indicated that 99mTc-NCAM bound to a single site on the NMDA receptor with a K d of 701.21 nmol/l and a B max of 62.47 nmol/mg. Specific inhibitors of the NMDA receptor, ketamine and dizocilpine, but not the dopamine D2 and 5HT1A receptor partial agonist aripiprazole, inhibited specific binding of 99mTc-NCAM to the NMDA receptor. Cell physiology experiments showed that NCAM can increase the viability of SH-SY5Y cells after glutamate-induced injury. Conclusions: The new radioligand 99mTc-NCAM has good affinity for and specific binding to the NMDA receptor, and easily crosses the blood–brain barrier; suggesting that it might be a potentially useful tracer for NMDA receptor expression. [Copyright &y& Elsevier]