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On a fattening pig farm all 582 animals died of peracute intoxication with hydrogen sulphide (H2S). The accident took place after 6000 litres of lactic acid (41.5 mass %) was dumped in the slurry pit. The volume of released gas was about 575 m3. This resulted in sudden spreading by high pressure of a lethal concentration of hydrogen sulphide to all compartments of the pig house. Analysis of the situation indicated that the level of hydrogen sulphide was 7870 ppm.  相似文献   
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Leachate from a waste tip in the acidification stage contains a lot of volatile fatty acids. Soil column experiments showed that the removal of these acids in soil by CH4-fermentation can be quite effective, especially in soils with a high buffering capacity. In sandy loam soil columns, where the retention time was only 17 days, the fatty acids were removed completely, even at a high concentration level of 6500 mg l?1 acetic acid equivalents. In sandy soils with a low buffering capacity the CH4-fermentation was already limited at rather low acid concentrations. The lag in the start of CH4-fermentation became longer at higher acid concentrations. At a level of 25 000 mg l?1 acetic acid equivalents CH4 -fermentation did not start within the test period of 10 months. The lowering of pH was probably the main reason for this phenomenon.  相似文献   
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Two hundred feral cats from the inner suburbs of Sydney were examined post mortem for adult Dirofilaria immitis and circulating microfilariae, and 101 of these cats were tested for heartworm antigens by an ELISA. Only 2 cats (1%) had adult heartworms, the blood sample from another cat contained a single microfilaria. The blood of a further three cats contained small amounts of D immitis antigen. Although D immitis occurs in cats in Sydney, the prevalence is not high enough to warrant prophylactic treatment.  相似文献   
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Synaptic efficacy critically depends on the presynaptic intracellular calcium concentration ([Ca2+]i). We measured the calcium sensitivity of glutamate release in a rat auditory brainstem synapse by laser photolysis of caged calcium. A rise in [Ca2+]i to 1 micromolar readily evoked release. An increase to >30 micromolar depleted the releasable vesicle pool in <0.5 millisecond. A comparison with action potential-evoked release suggested that a brief increase of [Ca2+]i to approximately 10 micromolar would be sufficient to reproduce the physiological release pattern. Thus, the calcium sensitivity of release at this synapse is high, and the distinction between phasic and delayed release is less pronounced than previously thought.  相似文献   
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Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely resembling the Egyptian genus Bahariasaurus. Comparisons with Cretaceous theropods from other continents reveal a previously unrecognized global radiation of carcharodontosaurid predators. Substantial geographic differentiation of dinosaurian faunas in response to continental drift appears to have arisen abruptly at the beginning of the Late Cretaceous.  相似文献   
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