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Agricultural tillage practices play an important role in the production and consumption of greenhouse gases (GHGs) that contribute substantially to the global warming. To explore GHG diffusion characteristic and seek for environment-friendly tillage methods, four tillage systems consisting of continuous rotary tillage (CR), continuous no tillage (CN), ploughing-rotary tillage (PR), and ploughing-no tillage (PN) were designed, and vertical variations of GHG concentrations under different tillage systems were investigated. Mean CO2 concentration in the soil profile was increased significantly with the increase of soil depth. Higher soil moisture promoted CO2 production. However, the influence of soil temperature on the content of CO2 was not obvious. The concentrations of CH4 in soil at 0–20-cm depth were greater than that of 20–40 cm, which was mainly affected by fertilization. The trend of N2O concentration variation in soil was consistent with that of CO2. The diffusion flux of CO2 in soil was all positive, and it changes greatly in the whole growth cycle of maize, which had obvious correlation with precipitation. The CH4 diffusion flux decreased with the increase of soil depth, and the change trend of 0–20-cm soil layer diffusion flux was consistent with the gas concentration. The 20–40-cm soil layer fluctuated greatly, which was mainly affected by water content, and the whole value was negative after jointing. The trend of N2O diffusion flux was similar to that of CH4. In the whole maize growth period, except for CH4 in 20–40-cm soil layer, the cumulative diffusion fluxes of greenhouse gases in each treatment were all positive, indicating that the whole farmland soil was the emission source of greenhouse gases. The effect of three greenhouse gases on greenhouse effect was CO2 > N2O > CH4, and the comprehensive warming potential of different tillage methods was CN > CR > PR> PN. So PN is the best tillage mode to reduce GHG emissions in soil profile under the test conditions.

An appropriate tillage method must be implemented by maize growers to improve phosphorus dynamics in the soil in order to increase phosphorus uptake by plant. The objective of this study was to investigate the effects of tillage systems on phosphorus and its fractions in rhizosphere and non-rhizosphere soils under maize. An experimental field was established, with phosphate fertilizers applied to four treatment plots: continuous rotary tillage (CR), continuous no-tillage (CN), plowing-rotary tillage (PR), and plowing-no tillage (PN). Under the different tillage methods, the available P was increased in the non-rhizosphere region. However, the concentration of available P was reduced in the rhizosphere soil region. The soil available P decreased with the age of the crop until the maize reached physiological maturity. The non-rhizosphere region had 132.9%, 82.5%, 259.8%, and 148.4% more available P than the rhizosphere region under the CR, PR, CN, and PN treatments, respectively. The continuous no-tillage method (CN) improved the uptake of soil phosphate by maize. The concentrations of Ca2-P, Ca8-P, Fe-P, Al-P and O-P at the maturity stage were significantly lower than other seedling stages. However, there was no significant relationship between total P and the P fractions. Therefore, a continuous no-tillage method (CN) can be used by farmers to improve phosphorus availability for spring maize. Soil management practices minimizing soil disturbance can be used to impove phosphorus availability for maize roots, increase alkaline phosphatase activity in the rhizosphere soil and increase the abundance of different phosphorus fractions.

Animal wastes are potential sources of natural and steroidal estrogen hormones into the environment. These hormones can be removed by microorganisms with induced enzymes. Two strains of 17β-estradiol-degrading bacteria (LM1 and LY1) were isolated from animal wastes. Based on biochemical characteristics and 16 S rDNA gene sequences, we identified strains LM1 and LY1 as belonging to the genus of Acinetobacter and Pseudomonas, respectively. Bacterial co-culture containing LM1 and LY1 bacterial strains could rapidly remove approximately 98% of E2 (5 mg L−1) within 7 days. However, strains LM1 and LY1 degraded 77% and 68% of E2 when they were incubated alone, respectively. More than 90% of 17β-estradiol (E2, ≤ 20 mg L−1) could be removed by bacterial co-culture. Low C/N ratio (1:35) was more suitable for bacterial growth and E2 degradation. The optimal pH for bacterial co-culture to degrade E2 ranged from 7.00 to 9.00. Coexisting sodium acetate, glucose and sodium citrate decreased E2 degradation in the first 4 days, but more E2 was removed when they were depleted. The growth of the bacterial co-culture was not significantly decreased by Ni, Pb, Cd or Cu at or below 0.8, 1.2, 1.6 or 0.8 mg L−1, respectively. These data highlight the usefulness of bacterial co-culture in the bioremediation of estrogen-contaminated environments.

In this paper, we focus on efficient construction of restricted subtree (RSubtree) results for XML keyword queries on amulticore system. We firstly show that the performance bottlenecks for existing methods lie in 1) computing the set of relevant keyword nodes (RKNs) for each subtree root node, 2) constructing the corresponding RSubtree, and 3) parallel execution. We then propose a two-step generic top-down subtree construction algorithm, which computes SLCA/ELCA nodes in the first step, and parallelly gets RKNs and generates RSubtree results in the second step, where genericmeans that 1) our method can be used to compute different kinds of subtree results, 2) our method is independent of the query semantics; top-down means that our method constructs each RSubtree by visiting nodes of the subtree constructed based on an RKN set level-by-level from left to right, such that to avoid visiting as many useless nodes as possible. The experimental results show that our method is much more efficient than existing ones according to various metrics.

Bulk material processed by the severe plastic deformation (SPD) technique were found possessing unique physical and mechanical properties [1–3]. SPD material were either nonferrous metal or soft steel. Recently, some researchers attempted to apply this technique to hard-to-work materials [4]. The present authors developed a new SPD process named Cylinder Covered Compression (CCC) and applied it to nodular iron [5]. Our previous work showed that graphite nodules became small with two extended tails along the direction transverse to the compressing force during hot-compression. After severe deformation, a large number of graphite flakes formed a lamellar structure with the metal matrix. This study aimed to build a deformation model of graphite in hot-compressed nodular iron, and then the model was used to explain why graphite area fraction increased on the axial sections of the specimen after more than 80% reduction. The nodular iron was obtained from the China Railway Shanhaiguan Bridge Co. Ltd, as 22.6 mm thick plates with a chemical composition (mass%) of 3.57C, 2.55Si, 0.22Mn, 0.021P, 0.013S and the balance in Fe. A new SPD process, named Cylinder Covered Compression (CCC), was developed by the present authors. The schematic illustration of the CCC process is shown in Fig. 1. Specimens, 8 mm in diameter with a 20 mm height, were machined from the cast plates. Cylinders of an 8 mm inner diameter and 10 mm outer diameter were made of medium carbon steel (0.45%C). The specimens enclosed by the cylinders were compressed on a Gleeble 3500 Machine. The details of the thermomechanical treatments are listed in Table I. The 30, 50, 65 and 80% deformed specimens were prepared by one pass of hot-compression. The 80% deformed specimens were cut into pieces, had surface layers ground away, were then stacked, embedded in a cylinder, and hotcompressed again. The 94% deformed specimen was prepared by two passes of about 80% hot-compressions.