纳米磺化石墨烯用于异位洗脱污染土壤多环芳烃工艺的优化

Ex-situ soil washing technology offers advantages such as speed and efficiency of remediation and range of application and has been developed to conform with legal requirements and best management practices in USA and some European countries. In this study,nano-sulfonated graphene(SGE) was used as a washing agent to evaluate different processing(washing) parameters for the ectopic leaching removal of polycyclic aromatic hydrocarbons(PAHs) from a coking plant soil. X-ray photoelectron spectroscopy(XPS) and fourier transform infrared spectroscopy(FTIR) were used to analyze the characteristics of the SGE tested. The results showed that SGE had a strong adsorption capacity for PAHs through the role of π-π, H-π, and anion-π interactions. The washing parameters, an SGE concentration of 2 000 mg L~(-1), a liquid/soil(L/S) ratio of 10:1, and 4 cycles of successive washing, were set to arrive to the optimum condition for achieving more than 80% of PAH removal. Under the optimum condition, the PAH removal rate decreased with increasing ring numbers. After one washing cycle at SGE concentration of 2 000 mg L~(-1) and L/S ratio of 10:1, the PAH removal rate of the SGE tested was much higher than that of Tween 80(TW80) or methyl-β-cyclodextrin(MCD)(P 0.01). Therefore, SGE is a promising material for the nanoremediation of PAH-contaminated soils.     

Origin of rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) domestication genes

A number of genes that contribute to the domestication traits of cultivated rice have been identified. These include Sh4, Rc, PROG1 and LABA1, which are associated with non-shattering rachis, white pericarp, erect growth and barbless awns, respectively. The mutations giving rise to the “domestication alleles” of these genes are either invariable in cultivated rice, or have variability that is strictly associated with the phenotypic trait. This observation forms the basis to those current rice domestication models that envisage a single origin for the domesticated phenotype. Such models assume that the domestication alleles are absent or rare in wild rice, emerged under cultivation and spread across all rice groups by introgressive hybridization. We examined whole-genome sequencing datasets for wild and cultivated rice to test the former two assumptions. We found that the rc and laba1 alleles occur in wild rice with broad geographical distribution, and reach frequencies as high as 13 and 15%, respectively. These results are in agreement with previous observations of the prog1 and sh4 domestication alleles in wild populations. We also show that the diversity of the genomic regions surrounding the rc, laba1, prog1 and sh4 alleles in wild accessions is greater than that in cultivated rice, suggesting that these alleles emerged prior to domestication. Our findings indicate that the possibility that independent rice groups obtained identical domestication alleles directly from the wild population needs to be considered.     

Evaluation of ground grain versus pre- and post-pellet whole grain additions to poultry diets via a response surface design

1. The objective of this study was to compare the effects of pre- and post-pellet whole grain wheat additions to diets on growth performance, gizzard and pancreas development, nutrient utilisation and starch and protein (N) digestibility coefficients in broiler chickens via an equilateral triangle response surface design.

2. The three apical treatments of the equilateral triangle comprised (1A) a standard diet containing 600 g/kg ground wheat, (2B) the same diet containing 600 g/kg pre-pellet whole wheat and (3C) the same diet containing 300 g/kg ground wheat and 300 g/kg post-pellet whole wheat. Seven blends of the three apical diets were located within the triangle to complete the design and a total of 360 male Ross 308 chicks were offered the ten experimental diets from 7 to 28 d post-hatch. Model prediction and response surface plots were generated with R 3.0.3 software.

3. The most efficient FCR of 1.466 was observed in birds offered an almost equal mixture of the pre- and post-pellet whole grain apical dietary treatments, which corresponded to 172 g/kg ground grain, 256 g/kg pre-pellet whole grain, 172 g/kg post-pellet whole grain in a diet containing 600 g/kg wheat.

4. The most efficient energy utilisation (ME:GE ratio of 0.766) was observed in birds offered a blend of the ground grain and pre-pellet whole grain apical dietary treatments which corresponded to a mixture of 384 g/kg pre-pellet whole grain and 216 g/kg ground grain.

5. Pre-pellet whole grain feeding generated the most pronounced responses in increased relative gizzard contents, reduced gizzard pH and increased relative pancreas weights. Consideration is given to the likely differences between pre- and post-pellet whole grain feeding.     

Marine myxobacteria as a source of antibiotics--comparison of physiology, polyketide-type genes and antibiotic production of three new isolates of Enhygromyxa salina

Three myxobacterial strains, designated SWB004, SWB005 and SWB006, were obtained from beach sand samples from the Pacific Ocean and the North Sea. The strains were cultivated in salt water containing media and subjected to studies to determine their taxonomic status, the presence of genes for the biosynthesis of polyketides and antibiotic production. 16S rDNA sequence analysis revealed the type strain Enhygromyxa salina SHK-1(T) as their closest homolog, displaying between 98% (SWB005) and 99% (SWB004 and SWB006) sequence similarity. All isolates were rod-shaped cells showing gliding motility and fruiting body formation as is known for myxobacteria. They required NaCl for growth, with an optimum concentration of around 2% [w/v]. The G + C-content of genomic DNA ranged from 63.0 to 67.3 mol%. Further, the strains were analyzed for their potential to produce polyketide-type structures. PCR amplified ketosynthase-like gene fragments from all three isolates enhances the assumption that these bacteria produce polyketides. SWB005 was shown to produce metabolites with prominent antibacterial activity, including activity towards methicillin resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE).     

Fungal disease suppression by inorganic salts: A review

This paper reviews the scientific literature on the topic of fungal disease suppression by applications of inorganic salts as alternatives to synthetic fungicides on a global scale for both protected and field crops. Where data were available, the comparative efficacy of inorganic salts with conventional fungicide products is discussed. In total, published evidence was found for 34 inorganic salts (mainly bicarbonates, phosphates, silicates, chlorides and phosphites) that were able to reduce the severity of 49 fungal diseases (of the foliage, stem, fruit, tuber, root and post-harvest) in 35 plant species (vegetables, cereals, fruit crops, root/tuber crops, ornamentals and native plants). The most studied and best controlled disease with inorganic salts was powdery mildew of cucurbits [Sphaerotheca fuliginea (Schltdl.) Pollacci 1913 or Erysiphe cichoracearum DC. 1805; up to 99% efficacy], wheat [Blumeria graminis (DC.) Speer 1975 (f. sp. tritici)] and grapes [Uncinula necator (Schwein.) Burrill 1892]. The next best evidence for disease control was for wheat septoria blotch (Septoria tritici Berk. & M.A. Curtis 1874), rice blast [Magnaporthe grisea (T.T. Hebert) M.E. Barr 1977], potato late blight [Phytophthora infestans (Mont.) de Bary 1876] and several other Phytophthora spp. The published evidence suggests that these 34 inorganic salts are generally less effective than conventional fungicides and could not fully replace them. However, their integration in a disease management strategy may enable a reduction in the number of conventional fungicide applications required. The potential for the inclusion of inorganic salts in fungal disease management programmes merits further investigation and greater regulatory innovation in the near future.     

The effect of simulated rat damage on irrigated rice yield and compensation

A field experiment was conducted to investigate the impact of simulated rat damage on grain yield in irrigated lowland rice in An Giang province, in the Mekong Delta of Vietnam. Rat damage was simulated by making a 45° cut at the base of the rice tillers about 3–5 cm above the soil surface. 0% (control), 5%, 10%, 25% and 50% of the tillers were removed at the tillering (25 days after sowing, DAS), panicle initiation (43 DAS), flowering (72 DAS) and ripening (87 DAS) stages. The total number of mature tillers, immature tillers and percent filled grains, the weight of 1000 grains and grain yields were recorded. The rice crop completely compensated by increased tillering and yield for tillers damaged up to 50% at the tillering stage. However, the damage and yield loss were highly variable. The ability of the rice crop to compensate at later stages progressively reduced. The implications for managing rat damage to rice crops are (1) rodent control activities should be applied before 10% of tillers are damaged at the tillering stage, and (2) a well balanced nitrogen supply during the tillering stage could potentially assist the rice plants to better compensate for rat damage.     

Effects of the essential oil constituent thymol and other neuroactive chemicals on flight motor activity and wing beat frequency in the blowfly Phaenicia sericata

BACKGROUND: The effects were evaluated of the plant terpenoid thymol and eight other neuroactive compounds on flight muscle impulses (FMIs) and wing beat frequency (WBF) of tethered blowflies (Phaenicia sericata Meig.). RESULTS: The electrical activity of the dorsolongitudinal flight muscles was closely linked to the WBF of control insects. Topically applied thymol inhibited WBF within 15–30 min and reduced FMI frequency. Octopamine and chlordimeform caused a similar, early‐onset bursting pattern that decreased in amplitude with time. Desmethylchlordimeform blocked wing beating within 60 min and generated a profile of continuous but lower‐frequency FMIs. Fipronil suppressed wing beating and induced a pattern of continuous, variable‐frequency spiking that diminished gradually over 6 h. Cypermethrin‐ and rotenone‐treated flies had initial strong FMIs that declined with time. In flies injected with GABA, the FMIs were generally unidirectional and frequency was reduced, as was seen with thymol. CONCLUSIONS: Thymol readily penetrates the cuticle and interferes with flight muscle and central nervous function in the blowfly. The similarity of the action of thymol and GABA suggests that this terpenoid acts centrally in blowflies by mimicking or facilitating GABA action. Copyright © 2009 Society of Chemical Industry     

The effect of temperature and other factors on chlorophyll a fluorescence and the lower oxygen limit in apples (Malus domestica)

The effects of temperature, scan interval and rate of oxygen (O₂) decline on pulse frequency modulation (PFM)-based minimum fluorescence (F_α) and the F_α-based lower oxygen limit (LOL) were investigated using ‘Honeycrisp’ apples (Malus × domestica Borkh). The effects of temperature and hypoxic stress on pulse amplitude modulation (PAM) fluorescence parameters were also investigated. The PFM scan interval had no effect on the F_α baseline, but increases in the scan interval decreased the low-O₂-induced fluorescence spike intensity (ΔF_α). Temperature negatively correlated with the F_α baseline while ΔF_α °C⁻¹ was greater at lower than at higher temperatures. When using a PAM fluorometer, the minimum fluorescence (F_o), and to a lesser extent the maximum fluorescence (F_m), were similarly affected by temperature as was F_α. Temperature altered the LOL in fruit. Apples stored at 20, 10, 3.5 and 0 °C spiked at 0.72, 0.33, 0.22 and 0.08 kPa O₂, respectively, under a rapid O₂ decline (i.e., 20.9 to <1 kPa O₂ in ≈5–6 h). Although the low-O₂ F_α spike apex values did not change with temperature, the spike intensity increased with temperature due to a reduced fluorescence baseline. A slower O₂ decline rate produced slightly higher LOL and lower spike intensity values. In conclusion, temperature and rate of O₂ decline affected the low-O₂-induced PFM fluorescence spike intensity as well as the LOL, while the PFM scan interval affected the spike intensity.