Remediation of petroleum contaminated soils by joint action of Pharbitis nil L. and its microbial community

The plot-culture experiments were conducted for examining the feasibility of Pharbitis nil L. and its microbial community to remedy petroleum contaminated soils. The petroleum contaminated soil, containing 10% (w/w) of the total petroleum hydrocarbons (TPHs), was collected from the Shengli Oil Field, Dongying City, Shandong Province, China. The collected soil was applied and diluted to a series of petroleum contaminated soils (0.5%, 1.0%, 2.0% and 4.0%). Root length, microbial populations and numbers in the rhizosphere were also measured in this work. The results showed that there was significantly (p < 0.05) greater degradation rate of TPHs in vegetated treatments, up to 27.63-67.42%, compared with the unvegetated controls (only 10.20-35.61%), after a 127-day incubation. Although various fractions of TPHs had an insignificant concentration difference due to the presence of the remediation plants, there was a much higher removal of saturated hydrocarbon compared with other components. The biomass of P. nil L. did not decrease significantly when the concentration of petroleum hydrocarbons in soil was ≤ 2.0%. The trends of microbial populations and numbers in the rhizosphere were similar to the biomass changes, with the exception that fungi at 0.5% petroleum contaminated soil had the largest microbial populations and numbers.     

新型TCAS树脂吸附水中三氯甲烷研究

通过静态吸附试验,研究一种由超分子受体化合物磺化硫杂杯芳烃(TCAS)与树脂结合的产物-新型TCAS树脂对水体中三氯甲烷的吸附去除性能.结果表明,对于25 mL质量浓度为1mg·L~(-1)的三氯甲烷污染水,投加0.5g TCAS树脂吸附40min后,去除率可达99％以上.TCAS树脂对三氯甲烷吸附的操作温度应控制在5～15℃左右为最佳.pH是影响TCAS树脂吸附效果的重要因素,在pH=6～8时去除效果较好.Ca~(2+)和Mg~(2+)背景阳离子的存在会加快TCAS树脂对三氯甲烷的吸附速率.在试验范围内,TCAS树脂对三氯甲烷吸附符合Freundlich方程.伪二级反应动力学方程能够较好地描述TCAS树脂对三氯甲烷的吸附过程.     

A novel photoelectrocatalytic system for organic contaminant degradation on a TiO2 nanotube (TNT)/Ti electrode

A novel degradation system, combined with photon-efficient thin-film photocatalysis, conventional bulk-phase photocatalysis and photocarrier-efficient electrocatalysis (TBPE), was developed on a vertically ordered one-dimensional (1D) TiO₂ nanotube (TNT)/Ti electrode for the purification of organics. The TBPE system possessed excellent optical, electrochemical, photoelectrochemical and photoelectrocatalytic properties as well as a high mass-transfer coefficient and interfacial activity. The combined degradation of methyl orange (MO) was optimized by varying the rotation angular velocity, applied bias and substrate concentration, and a photoelectrochemical synergetic effect of 62.2% was observed under the optimized conditions for TBPE compared to the individual electrocatalytic (EC) and photocatalytic (PC) systems. To explore the mechanisms, the combined thin-film degradation system of photon-efficient thin-film photocatalysis with photocarrier-efficient electrocatalysis (TPE), and the combined bulk-phase degradation system of conventional bulk-phase photocatalysis with photocarrier-efficient electrocatalysis (BPE), were comparatively estimated. A dramatic increase of 29.4-74.4% was observed in the MO removal efficiency via the thin-film TPE system compared to the bulk-phase BPE system. The results indicated that in the proposed TBPE system on the 1D TNT electrode, the predominant degradation occurred via the TPE system due to its excellent UV utilization efficiency and resultant interfacial photoactivity.     

Effects of fertilization on nutrient budget and nitrogen use efficiency of farmland soil under different precipitations in Northeastern China

Based on a consecutive 16-year field trial and meteorological data, the effects of fertilization on the nutrient budget and nitrogen use efficiency in farmland soil under different precipitation years were studied. With no fertilization treatment, the grain yield of maize was 3,520 kg ha⁻¹ (mean yield over 13 years). But the maximum yield increased to 7,470 kg ha⁻¹ when treated with mineral N, P and K fertilizers and recycled manure. The nutrient uptake also increased by twofold to threefold in NPKM treated field compared with that in the control treatment. The highest yields were obtained in years with normal precipitation, despite the different fertilization schemes. The lowest yields were obtained in drought or waterlogging years, which were 44.7–58.5% of the yields in years with normal precipitation. It also appeared that the deficits of N, P and K were greater in the years with proper precipitation than those in arid or flood years, because more production was removed from the field. Soil total N decreased significantly when treated with mineral fertilizer or recycled manure alone. The maximum deficit of soil total N was observed in control treatment (557 kg ha⁻¹) from 1990 to 2005. The N treatment resulted in a significant negative balance of P, due to the high yield of the crop in response to applied N. The application of NP or N to soils resulted in a greater negative K balance than that of the control. The greatest negative balance of total P and available P were obtained under the control and N treatment, and the highest deficit of soil total K and exchangeable K were obtained under NP treatment. We found that the rate of 150 kg N ha⁻¹ year⁻¹ was inadequate for maintaining soil N balance, and amendment of soil with organic source could not stop the loss of soil P and K. The applying rates of 150 kg N ha⁻¹ year⁻¹, 25 kg P ha⁻¹ year⁻¹, and 60 kg K ha⁻¹ year⁻¹ combined with 2–3 t ha⁻¹ organic manure were recommended to maintain soil fertility level. The nitrogen use efficiency (NUE) was greatly improved in the years with proper precipitation and balanced fertilization. Higher NUE and grain yields were achieved under NPK and NPKM treatments in years with normal precipitation. The results clearly demonstrated that both organic and mineral fertilizers were needed to increase crop production, improve NUE and maintain soil fertility level.     

米曲霉CPA毒素的5-氟色氨酸分子探针研究

米曲霉中往往含有完整的环匹阿尼酸(cyclopiazonic acid,CPA)毒素生物合成基因簇.鉴于CPAs对食品安全的潜在威胁和其不同的存在形式,依据CPA的生物合成机制推测可将外源氟代前体探针化合物嵌入CPA生物合成途径,从而形成氟代物用于靶向检测.结果 显示,米曲霉CPA合成途径可以接受5-F-L-Trp为底...     

High-performance La–Mg–Ni-based alloys prepared with low cost raw materials

La–Mg–Ni-based hydrogen storage alloys showed good application prospects owing to their high hydrogen storage capacity. However, the poor cycling stability was a key problem. In order to improve the cycling stability, low cost YFe_0.85 master alloy was used as raw material to prepare La–Mg–Ni-based La_0.8-xY_xMg_0.2Ni_3-0.85xFe_0.85x (x = 0.50, 0.55, 0.60) hydrogen storage alloys by powder sintering method. The alloys were mainly composed of PuNi₃ phase and MgCu₄Sn phase. With the increase of Y and Fe, the cell parameters of PuNi₃ phase decreased. Lower mismatch coefficient promoted the cycling stability. As the case of x = 0.60, the capacity retention rate rose up to 95.45%. Aside from the cycling stability, appropriate substitution content contributed to higher capacity and satisfactory kinetics. As the case of x = 0.55, the hydrogen storage capacity reached 1.529 wt%, and hydriding time for the x = 0.60 alloy shrank to 76.7% of that for alloys without Y and Fe at 303 K.     

Food-web structure in low- and high-dimensional trophic niche spaces

A question central to modelling and, ultimately, managing food webs concerns the dimensionality of trophic niche space, that is, the number of independent traits relevant for determining consumer–resource links. Food-web topologies can often be interpreted by assuming resource traits to be specified by points along a line and each consumer''s diet to be given by resources contained in an interval on this line. This phenomenon, called intervality, has been known for 30 years and is widely acknowledged to indicate that trophic niche space is close to one-dimensional. We show that the degrees of intervality observed in nature can be reproduced in arbitrary-dimensional trophic niche spaces, provided that the processes of evolutionary diversification and adaptation are taken into account. Contrary to expectations, intervality is least pronounced at intermediate dimensions and steadily improves towards lower- and higher-dimensional trophic niche spaces.     

Comparing the characteristics of front and back domestic gardens in Hobart,Tasmania, Australia

In Australia, suburban front gardens have been said to be for show, while back gardens have been thought to be used more productively. This pattern may have changed as a result of a change in the ways that western suburbanites use and value their gardens. In 107 gardens in 10 suburbs of Hobart, Tasmania, Australia, data on the floristic composition, structural characteristics and some use attributes were collected from front and back yards. The floristic data were used to classify the yards into types, many of which preferentially occurred in either front or back. Back yards preferentially containing food plant taxa, and had a larger proportion of lawn, dogs and chicken coops, while front yards preferentially contained showy and screening plant taxa, and had relatively high small shrub cover. However, in a large proportion of properties, the garden type in the front yard was the same as the type in the back yard. In another large proportion of properties the front yard was gardened more intensively than the back, indicating a desire to impress, but the back yard was not used for productive purposes. These gardens preferentially occurred in the older suburbs, while gardens that were showier in the back than the front were negatively correlated with the unemployment rate. In a relatively small proportion of properties showy gardens were located in the front yard, while productive gardens were located in the back yard. The prevalence of these gardens had no relationships with suburb characteristics. The wide variety of garden types, and of their combinations in back and front yards, both within and between suburbs, indicate a complexity not reducible to simple aphorisms.     

Spatially constrained coordinated navigation for a multi-robot system

In this paper we present a method for navigating a multi-robot system through an environment while additionally maintaining a predefined set of constraints. Examples for constraints are the requirement to maintain a direct line-of-sight between robots or to ensure that the multi-robot system maintains communication. Our approach is based on graph structures that model movements and constraints separately, in order to cover different kind of robots and a large class of possible constraints. Additionally, the separation of movement and constraint graph allows us to use known graph algorithms like Steiner tree heuristics or the multi-point relay algorithm to solve the problem of finding a target configuration for the robots. To connect the movements of the robots with the given constraints, we introduce separated connection graphs which allow assembling valid navigation plans fast. This paper presents some theoretical insight into the problem of coordinated navigation for multi-robot systems with spatial constraints as well as a practical solution. Experiments in simulation and with real robots show the feasibility of the approach.