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991.
Huayong Wu Wenli Chen Xingmin Rong Peng Cai Ke Dai Qiaoyun Huang 《Journal of Soils and Sediments》2014,14(3):504-514
Purpose
Bacterial adhesion to soil particles is fundamentally important in mineral weathering, organic matter degradation, heavy metal transformation, and fate of pollutants. However, the adhesion mechanism between bacteria and soil colloids under continuous flow systems in the natural environments remains unknown.Materials and methods
The kinetics of Pseudomonas putida cellular adsorption and desorption on Red soil colloid films under controlled flow systems were examined using in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Derjaguin–Landau–Verwey–Overbeek (DLVO) and non-DLVO interactions were employed to elucidate the cellular adsorption and desorption kinetics.Results and discussion
In situ ATR-FTIR spectroscopy can be used effectively to investigate the kinetics of bacterial adhesion to a soil colloid deposit. Surface proteins may be involved in the bacterial adhesion to soil colloids. The adsorption followed pseudo-first-order kinetic equation. High adsorption rate constant and great saturation coverage of adsorbed bacteria were found at high ionic strengths in dynamic systems.Conclusions
P. putida bacterial cellular adsorption on the soil colloid deposit was irreversible in a wide range of ionic strengths under controlled flow systems. The less reversible adhesion was probably attributed to the DLVO predicted deep secondary energy minima together with non-DLVO factors including polymer bridging, local charge heterogeneities, surface roughness, and Lewis acid–base interactions. 相似文献992.
Purpose
The beneficial effect to the environment of nitrate (NO3 ?) removal by denitrification depends on the partitioning of its end products into nitrous oxide (N2O), nitric oxide (NO), and dinitrogen (N2). However, in subtropical China, acidic forest mineral soils are characterized by negligible denitrification capacity and thus reactive forms of N could not be effectively converted to inert N2, resulting in a negative environmental consequence. In this study, the influences of C input from litter decomposition on denitrification rate and its gaseous products under anoxic conditions in the acidic coniferous and broad-leaved forest soils in subtropical China were investigated using the acetylene (C2H2) blockage technique in the laboratory.Materials and methods
The coniferous and broad-leaved forest soils with and without litter addition were incubated under anaerobic conditions for 244 h. There were three treatments for each forest soil including addition of 0.5 and 1% corresponding litter (gram of litter per gram of soil) and the control without addition of litter.Results and discussion
The results showed that litter addition into the broad-leaved forest soil had no effect on average rates of denitrification (calculated as the sum of NO, N2O, and N2), whereas in the coniferous forest soil, the addition resulted in a significant increase in average denitrification rate. In the broad-leaved forest soil, both rates of litter addition decreased the production of NO but increased the production of N2, and high rates of litter addition into the coniferous forest soil promoted the reduction of N2O to N2.Conclusions
Increased decomposition of litter in the forest soils could effectively reduce N2O and NO production through denitrification under anaerobic conditions. 相似文献993.
994.
Residual feed intake (RFI) is a measure of feed efficiency defined as the difference between observed and predicted feed intake based on average requirements for growth and maintenance. The objective of this study was to evaluate the effect of selection for decreased RFI on feeding behavior traits and to estimate their relationships with RFI. Three data sets from the 4th and 5th generations of a selection experiment with a line selected for reduced RFI (LRFI) and a randomly selected control line (CTRL) were analyzed. Lines were mixed in pens of 16 and evaluated for feeding behavior traits obtained from a single-space electronic feeder over a growing period of ~3 mo before ~115 kg. The following traits were evaluated as averages over the entire test period and over the first and second half of the test period: number of visits per day and hour; occupation time per day, visit, and hour; feed intake (FI) per day, visit, and hour; and FI rate per visit. Models used included fixed effects of line and feeder, covariates of on-test age and FI per day, and random effects of pen, on-test group, sire, and litter. Repeated measures models were used to analyze feeding patterns during the day. The LRFI pigs had significantly less FI per day than CTRL pigs for all 3 data sets. With adjustment for FI per day, line differences of all traits were in the same direction for all 3 data sets but differed in significance and size. Feed intake per visit and hour and visits per day and hour did not differ between lines, but the trend was for LRFI pigs to have fewer visits, in particular during peak eating times. The LRFI pigs had a greater feeding rate and less occupation time per day, visit, and hour than CTRL pigs, but this was not significant for all data sets. Correlations of RFI with FI per day and visit and visits per day were positive. Average daily gain was positively correlated with FI per day and visit and occupation time per visit but negatively correlated with visits per day. Feed intake per day was positively correlated with backfat. In conclusion, feed efficiency may be affected by FI behavior because selection for decreased RFI has resulted in pigs that spend less time eating and eat faster. 相似文献
995.
Wang G Song T Yu Y Liu Y Shi W Wang S Rong F Dong J Liu H Cai X Zhou EM 《Veterinary immunology and immunopathology》2011,142(3-4):170-178
Porcine reproductive and respiratory syndrome virus (PRRSV) infection compromises the host's innate and adaptive immunity. The aim of this study was to investigate the immune responses of piglets infected with highly pathogenic (HP) PRRSV (HuN4 strain) with or without the immunization with CH-1R attenuated PRRSV vaccine. The response was evaluated for the clinical signs, pathological changes and virus load in immune organs, antibody responses and levels of serum IFN-γ, IL-4 and IL-10. The result showed that in comparison with the piglets received the immunization, the piglets infected with HP-PRRSV alone had the thymus atrophy, decreased serum levels of IL-4 and increased serum levels of IL-10 and INF-γ. These results suggest that elevated IL-10 levels at the early stage of the infection may enhance virus survival and delay the induction of protective immunity, while increased levels of IL-4 induce the effective immune responses and increase the animals' health status. 相似文献
996.
Hou H Shen G Wu W Gong P Liu Q You J Cai Y Li J Zhang X 《Veterinary parasitology》2011,183(1-2):189-193
The aim of the present study was to estimate the prevalence and risk factors of Dirofilaria immitis infection in dogs from Dandong, China. A total of 886 dogs were examined for D. immitis infection by microscopic examination and PCR, indicating that the prevalence was 16.6% (213/886) and 24.0% (147/886), respectively. The odds of infection were significantly higher in older dogs and dogs sheltered in outdoor, compared to the younger ones and ones sheltered in indoor. No significant difference of infection was observed in different genders, and between pure breed and cross-breed dogs in the same rearing conditions. These results indicated that the risk of exposure to D. immitis in dogs is high in Dandong, China, and prophylaxis against the parasite is advisable to decrease the incidence of canine dirofilariosis. 相似文献
997.
Cai S Li J Wong MT Jiao P Fan H Liu D Liao M Jiang J Shi M Lam TT Ren T Leung FC 《Veterinary microbiology》2011,152(1-2):46-54
Complete genomes of four Newcastle disease virus (NDV) strains, isolated from ducks and wild birds in Guangdong province of China from 2003 to 2007, were sequenced and analyzed in this study. Pathogenicity tests in chicken embryos and chickens illustrate that D3 and R8 are lentogenic, and W4 and P4 are mesogenic strains. Phylogenetic analysis using all six genes provides a high resolution profile for genotype designation as genotype I for D3 and R8 strains and genotype VI for W4 and P4 strains. In addition, molecular dating based on different genes suggests that D3 and R8 diverged from their common ancestor at around 1998; W4 and P4 diverged from their common ancestor at around 1999. Subsequent selective pressure analysis displayed specific traits of genes evolution in all 4 strains since their divergence from the recent common ancestor. Furthermore, the geographic origins of 4 strains were deduced to be from Europe via two independent introduction events by phylogeographical analysis. This provides insights to the potential influence of waterfowl migration on NDV epidemiology. 相似文献
998.
999.
能量密度对低温等离子体辅助催化转化柴油机颗粒物和NOx的影响 总被引:2,自引:1,他引:1
为了研究低温等离子体辅助催化后处理技术对柴油机有害排放物的作用效果,基于介质阻挡放电理论设计了低温等离子体(NTP)发生器,研究了NTP发生器工作电压随能量密度的变化关系。以涂覆γ-Al2O3的蜂窝状陶瓷为载体,采用柠檬酸凝胶法制备了LaMnO3催化剂,建立了NTP辅助LaMnO3催化试验系统。在台架试验基础上,研究了能量密度变化对NTP辅助LaMnO3催化技术转化(颗粒物)PM和NOx的影响规律。试验结果表明:在相同频率作用下,NTP发生器的能量密度随着工作电压的升高而增加;与原机相比,NTP辅助LaMnO3催化技术作用后NO浓度显著降低,NO2浓度显著增加,NOx浓度降低;随着能量密度的增加,碳烟转化效果越明显,碳烟的不透光烟度最高降低约83%。结果表明NTP辅助LaMnO3催化技术可有效转化PM和NOx,在柴油机排气后处理领域有着广泛的研究前景。 相似文献
1000.
为提高电生功能水预处理玉米秸秆的效果,探讨了强化酸性电生功能水(acid electric water,AEW)性能指标的方法,包括在0℃下低温电解、先在强磁场下磁化再电解、往AEW中通入氯气等。结果表明,3种方法对AEW的pH值和氧化还原电位(oxidation-reduction potential,ORP)值都能起到一定程度的强化作用,通氯气的AEW强度最高,pH值能达到1.87,ORP值1226 mV。用强化的AEW(pH值1.92,ORP值1218 mV)、未经强化AEW(pH值2.30、ORP值1175 mV)和同pH值盐酸(pH值2.30)分别预处理玉米秸秆,结果发现强化的AEW去除半纤维素去除率为68%,高于未经强化的61%,远高于盐酸的53%。AEW的预处理效果明显优于同pH值盐酸,说明了氧化性对秸秆的木质纤维素预处理中半纤维素的去除有重要影响。该研究对拓展电生功能水应用领域和探求生物质预处理新方法有一定的启示。 相似文献