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1.
仔猪球虫病的最新资料 总被引:3,自引:0,他引:3
由于在仔猪球虫病发病、诊断、危害和防制方面的新发现,现在饲养和兽医对此病比以往任何时候都了解得更多。 相似文献
2.
Using the soil gas radon as an indicator for ground contamination by non-aqueous phase-liquids 总被引:1,自引:0,他引:1
Michael Schubert Klaus Freyer Hans-Christian Treutler Holger Weiß 《Journal of Soils and Sediments》2001,1(4):217-222
1 The Problem One of the major problems facing risk assessment at polluted industrial sites and military bases is subsurface contamination
by non-aqueous phase-liquids (NAPLs), since tracing the extent of a NAPL plume using conventional methods (drive point profiling)
is usually associated with difficulties. In an effort to trace subsurface contamination as precisely as possible, monitoring
points are placed in the area that might be affected by contaminants, and groundwater and soil samples are taken to the laboratory
for analysis. However, the final number of monitoring points is hardly ever sufficient for distinctive contamination mapping,
and this may ultimately result in an unsuitable remediation action being taken.
2 Objectives To obtain a more detailed image of a subsurface NAPL plume and, hence, to facilitate remediation measures that are best suited
for the site in question, a denser network of monitoring points is desirable. The aim of the investigation described in this
paper was therefore to develop a new detection method for subsurface NAPL contamination, which is based on an easily accessibleindicator for NAPLs rather than on the analysis of soil and groundwater samples taken at the site. Based on the good solubility of
radon in NAPLs, the idea was put forward that subsurface NAPL contamination should have an influence on the natural radon
concentration of the soil gas. Provided this effect is significant, it would be possible to carry out a straightforward radon
survey on an appropriate sampling grid covering the suspected site and thus enabling the NAPL contamination to be detected
by the localization of anomalous low radon concentrations in the soil. The overall aim of the investigation was to assess
the general suitability of the soil-gas radon concentration as an indirect tracer for NAPL contamination in the ground.
3 Methods The partitioning coefficient KNAPL/air is one of the most influential parameters governing the decrease of the radon concentration in the soil gas in the presence
of a subsurface NAPL contamination. Since NAPL mixtures such as gasoline, diesel fuel and paraffin are among the most important
NAPLs regarding remediation activities, laboratory experiments were performed to determine the radon-partitioning coefficient
for these three NAPL mixtures.
Field experiments were carried out as well. The aim of the field experiments was to test the use of the soil-gas radon concentration
as a tracer for NAPL contamination on-site. For the field experiments, each site was covered with a suitable grid of soil
gas sampling points. Finally, the lateral radon distribution pattern achieved on each of the sites was compared to the respective
findings of the earlier research performed by conventional means.
4 Results and Discussion The results of the laboratory experiments clearly show a very strong affinity of radon to the NAPL mixtures examined. The
partitioning coefficients achieved correspond to those published for pure NAPLs (Clever 1979) and are thus in the expected
range. The results of the field experiments showed that the minimum radon concentrations detected match the respective NAPL
plumes traced previously.
5 Conclusions Both the results of the lab experiments and the on-site findings demonstrate that the soil-gas radon concentration can be
used as an indicator for subsurface NAPL contamination. The investigation showed that NAPL-contaminated soil volumes give
rise to anomalous low soil-gas radon concentrations in the close vicinity of the contamination. The reason for this decrease
in the soil-gas radon concentration is the good solubility of radon in NAPLs, which enables the NAPLs to accumulate and ‘trap’
part of the radon available in the soil pores.
6 Recommendations and Outlook Further research is required into contamination with rather volatile NAPLs such as BTEX. Further research is also needed to
examine whether it is possible to not only localize a NAPL plume, but also to obtain some quantitative information about the
subsurface NAPL contamination. The authors also believe that additional investigations should be carried out to study the
ability of the method to not just localize a NAPL contamination, but also to monitor on-site, clean-up measures. 相似文献
3.
This study aims to elucidate the significance of compost and soil characteristics for the biological activity of compost‐amended soils. Two agricultural soils (Ap horizon, loamy arable Orthic Luvisol and Ah horizon, sandy meadow Dystric Cambisol) and a humus‐free sandy mineral substrate were amended with two biowaste composts of different maturity in a controlled microcosm system for 18 months at 5 °C and 14 °C, respectively. Compost application increased the organic matter mineralization, the Cmic : Corg ratio, and the metabolic quotients significantly in all treatments. The total amount of Corg mineralized ranged from < 1 % (control plots) to 20 % (compost amended Dystric Cambisol). Incubation at 14 °C resulted in 2.7‐ to 4‐fold higher cumulative Corg mineralization compared to 5 °C. The Cmic : Corg ratios of the compost‐amended plots declined rapidly during the first 6 months and reached a similar range as the control plots at the end of the experiment. This effect may identify the compost‐derived microbial biomass as an easily degradable C source. Decreasing mineralization rates and metabolic quotients indicated a shift from a compost‐derived to a soil‐adapted microbial community. The Corg mineralization of the compost amended soils was mainly regulated by the compost maturity and the soil texture (higher activity in the sandy textured soils). The pattern of biological activity in the compost‐amended mineral substrate did not differ markedly from that of the compost‐amended agricultural soils, showing that the turnover of compost‐derived organic matter dominated the overall decay process in each soil. However, a priming effect occurring for the Dystric Cambisol indicated, that the effect of compost application may be soil specific. 相似文献
4.
Siebert KJ 《Journal of agricultural and food chemistry》2001,49(2):851-858
A quantitative structure-activity relationship (QSAR) modeling approach based on the location of each amino acid along three axes obtained by principal component analysis (called z scores) was extended to physical and functional properties of proteins, where the proportion of particular amino acids rather than a precise sequence is the determining factor. Coomassie Brilliant Blue spectral responses to amino acid homopolymers (R = 0.926) and proteins, either as a function of their contents of six basic and aromatic amino acids (R = 0.976) or as a function of the contributions of these amino acids to the three z scores (R = 0.935), were modeled. The ultraviolet absorbance of proteins was modeled in terms of the z score contributions of tyrosine, tryptophan, and cysteine (R = 0.995). Modeling many protein functional properties in this manner appears to be possible. An approach to modeling peptide behaviors that depend on short sequences of amino acids was also considered. 相似文献
5.
Siebert U Müller G Desportes G Weiss R Hansen K Baumgärtner W 《The Veterinary record》2002,150(9):273-277
Staphylococcus aureus septicaemia was diagnosed in a dead, stranded harbour porpoise from the German Baltic Sea and in a live harbour porpoise by-caught in inner Danish waters and taken into captivity. Lesions included pyogranulomatous myocarditis, necrotising suppurative bronchopneumonia, pyelonephritis, osteomyelitis and leptomeningitis, and abscesses in lymph nodes and skeletal muscles. The captive animal had fibrinous suppurative epicarditis and pyogranulomatous myocarditis with abscesses. In both animals the organism was suspected to have entered through skin lesions or via the respiratory tract. 相似文献
6.
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8.
Effects of protein-polyphenol interactions on beverage haze, stabilization, and analysis 总被引:14,自引:0,他引:14
Siebert KJ 《Journal of agricultural and food chemistry》1999,47(2):353-362
The haze-forming activity of a polypeptide depends greatly on its proline content. Haze-forming polyphenols have at least two binding groups, each of which has at least two hydroxy groups on an aromatic ring. The protein/polyphenol ratio has a strong influence on the amount of haze formed; the largest amount occurs when the numbers of polyphenol binding ends and protein binding sites are nearly equal. This has important consequences for turbidimetric methods used to measure haze-active proteins and polyphenols in beverages. The ratio also influences the effectiveness of a number of stabilization procedures. 相似文献
9.
CX3CR1-mediated dendritic cell access to the intestinal lumen and bacterial clearance 总被引:3,自引:0,他引:3
Niess JH Brand S Gu X Landsman L Jung S McCormick BA Vyas JM Boes M Ploegh HL Fox JG Littman DR Reinecker HC 《Science (New York, N.Y.)》2005,307(5707):254-258
Dendritic cells (DCs) and macrophages are critical to innate and adaptive immunity to the intestinal bacterial microbiota. Here, we identify a myeloid-derived mucosal DC in mice, which populates the entire lamina propria of the small intestine. Lamina propria DCs were found to depend on the chemokine receptor CX3CR1 to form transepithelial dendrites, which enable the cells to directly sample luminal antigens. CX3CR1 was also found to control the clearance of entero-invasive pathogens by DCs. Thus, CX3CR1-dependent processes, which control host interactions of specialized DCs with commensal and pathogenic bacteria, may regulate immunological tolerance and inflammation. 相似文献
10.
The amygdalohippocampal circuit plays a pivotal role in Pavlovian fear memory. We simultaneously recorded electrical activity in the lateral amygdala (LA) and the CA1 area of the hippocampus in freely behaving fear-conditioned mice. Patterns of activity were related to fear behavior evoked by conditioned and indifferent sensory stimuli and contexts. Rhythmically synchronized activity at theta frequencies increased between the LA and the CA1 after fear conditioning and became significant during confrontation with conditioned fear stimuli and expression of freezing behavior. Synchronization of theta activities in the amygdalohippocampal network represents a neuronal correlate of conditioned fear, apt to improve neuronal communication during memory retrieval. 相似文献