Effect of Long-Term Straw Incorporation on SoilMicrobial Biomass and C and N Dynamics

A study was performed on the long-term effect of straw incorporation on soil microbial biomass C contents, C and N dynamics in both Rothamsted and Woburn soils. The results showed that for both soils,the microbial biomass C contents were significantly different among all the treatments, and followed the sequence in treatments of straw chopped and incorporated into 10 cm (CI10) > straw burnt and incorporated into 10 cm (BI10) > straw chopped and incorporated into 20 cm (CI20) > straw burnt and incorporated into 20 cm (BI20). Laboratory incubation of soils showed that the cumulative CO2 evolution was closely related to the soil microbial biomass C content. Carbon dioxide evolution rates (CO2-C, μg (g d) -1 ) decreased rapidly in the first two weeks’ incubation, then decreased more slowly. The initial K2SO4-extractable NH4-N and NO3-N contents were low and similar in all the treatments, and all increased gradually with the incubation time. However, net N immobilization was observed in chopped treatments for Rothamsted soils during the first 4 weeks. Nevertheless, more N mineralization occurred in neatment CI10 than any other treatment at the end of incubation for both soils. The Woburn soils could more easily suffer from the leaching of nitrate because the soils were more permeable and more N was mineralized during the incubation compared to the Rothamsted soils.

Dissolution Precipitation Wave Structure of Hydrothermal Ore Zoning

Hydrothermal ore zoning is a transport-reaction problem in which infiltration is the principal Prcness of transport and dissolution/Precipitation is the Principal process of chemical reactions.Neglecting diffusion and ion exchange/adsorption would not affect the basic attributes of hydrothermal ore zoning. Hydrothermal ore zoning belongs essentially to infiltration metasomatic zoning, it results from the formation and propagation of dissolution/precipitation waves through Permeable media. The authors apply the theory of coupled infiltration and dissolution/precipitation reactions in Physicochemical hydrodynamics to studying the structural characteristics of dissolution/precipitation waves, and apply furthermore the coherence principle in dynamic theory of multicomponent coupled systems to revealing the dynamic mechanisms of their formation. The results of investigation verify and develop . C. 's theory of infiltration metasomatic zoning,on the one hand, raising it from the qualitative, equilibrium thermodynamic basis to the quantitative dynamic level;on the other hand, and more importantly, applying theories of Physicochemical hydrodynamics and dynamics of multicomponent coupled systems to bringing to light the dynamic mechanisms of formation of the structure of hydrothermal ore zoning, and advancing a theory of hydrothermal ore zoning, putting forward new ideas on the nature of the problem of hydrothermal ore zoning, the essence of hydrothermal ore zoning and the structural characteristics and mechanisms of formation of hydrothermal ore zoning.

Dynamic performance of a C/C composite finger seal in a tilting mode

The complex operating state of aeroengines has an impact on the performance of finger seals. However, little work has been focused on the issue and the dynamic performance of finger seals is also rarely studied. Therefore, a distributed mass equivalent model considering working conditions is proposed in this paper for solving the existing problems. The effects of the fiber bundle density and the preparation direction of the fiber bundle of a C/C composite on the dynamic performance of a finger seal are investigated in rotor tilt based on the proposed model. The difference between the C/C composite finger seal performances under the rotor precession and nutation tilt cases is also investigated. The results show that the fiber bundle density and the preparation direction of the fiber bundle have an influence on the dynamic performance of the finger seal as rotor tilt is considered, and the dynamic performance of the finger seal is different in the two kinds of tilting modes. In addition, a novel method for design of finger seals is presented based on the contact pressure between finger boots and the rotor. Finger seals with good leakage rates and low wear can be acquired in this method.

Divergent effects of biochar amendment and replacing mineral fertilizer with manure on soil respiration in a subtropical tea plantation

Applying biochar amendment and manure in tea plantation ecosystems can diminish soil acidification and degradation.However,the impact of these practices on soil respiration and associated mechanisms remains unclear.In this study,we combined a two-year field experiment and laboratory analyses based on soil properties,functional genes,and microbial co-occurrence networks to explore the determinants of soil respiration intensity in a subtropical tea plantation with biochar amendment and manure application.The results showed that the effect of biochar amendment on soil respiration was unconspicuous.Although biochar amendment increased bacterial richness and Shannon index,biochar amendment did not alter the abundance of species associated with C-cycling functional genes.Besides directly adding recalcitrant C to the soil,biochar also indirectly enhanced C sequestration by weakly increasing soil carbon dioxide(CO_(2))emissions.However,replacing mineral fertilizer with manure significantly stimulated soil respiration in the tea plantation,resulting in a 36%increase in CO_(2) emissions over two years.The increase in CO_(2) emissions under the manure treatment was mainly attributed to the increased soil labile C pool,the activity of hydrolytic enzymes(e.g.,cellobiohydrolase and acetylglucosaminidase),and the relative abundance of functional genes associated with the C-cycle.This may also be related to the application of manure that increased the abundance of Gemmatimonadetes and altered ecological clusters in bacterial co-occurrence networks.Our correlation network analysis suggested that Gemmatimonadetes might be the potential hosts for C-cycling genes due to their strong positive correlation with the abundance of C-cycling genes.Overall,these findings provide new insights into soil respiration under biochar amendment and manure application in tea plantations and broaden the options for carbon sequestration in soils.

Cholesterol modulating the orientation of His17 in hepatitis C virus p7 (5a) viroporin--A molecular dynamic simulation study

Protein p7 of HCV is a 63 amino acid channel forming membrane protein essential for the progression ofviral infection and the sensitivity of this channel to small-molecule inhibitors renders p7 a potentialtarget for novel therapies against HCV infection. Previous biochemical experiments suggested that theHis17 of p7 is a pore-lining residue and solvated-exposed to participate in channel gating. However, arecent NMR structural identification of the p7 hexamer in dodecylphosphocholine （DPC） micellesindicated that the His17 is embedded into the protein matrix. In this work, we performed moleculardynamic simulations to bridge the controversial observations. Our results illustrated that byincorporating the cholesterol into DOPC membranes to mimic an actual membrane-like composition,the orientation of His17 in the hexameric bundles spontaneously access to the central pore region,indicating a versatile property of the p7 viroporin conformation that could be voluntarily influenced byits surrounding environments.