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931.
Hardsetting of soil comprises two contrasting, unfavourable physical conditions at different water contents, namely extreme hardness when dry and complete slaking when wet. This behaviour was changed by adding small amounts of ferrihydrite and aluminium hydroxide to the soil. The aggregation and its stability in the wet state increased, whereas the tensile strength of the dry soils decreased. Both resulted mainly by making the fine particles less mobile by aggregation. In some cases adding large amounts of Al hydroxide caused a resuspension of soil particles by reversing the charge, resulting in instability when wet and high stability when dry. We postulate that aggregation results from the interaction between negatively charged siliceous surfaces and positively charged oxides. In addition we think that newly formed Si–O–Fe bonds play a role in binding particles together as a result of a positive relation between the amount of ferrihydrite added and the oxalate-soluble Si. We conclude that hardsetting resulting from weak structure is caused by lack of aggregating agents such as metal hydroxides. 相似文献
932.
Quantitative determination and structure elucidation of type A- and B-trichothecenes by HPLC/ion trap multiple mass spectrometry. 总被引:4,自引:0,他引:4
A method is presented for the quantification and structure confirmation of trichothecenes in wheat by high-performance liquid chromatography combined with multiple mass spectrometry (MS(n)()). Nine type A- and B-trichothecenes were determined (nivalenol, deoxynivalenol, fusarenon-X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, neosolaniol, diacetoxyscirpenol, HT-2 toxin, and T-2 toxin). Extraction was carried out with acetonitrile/water. The extract was purified on a MycoSep column. Quantification was based on an internal standard and atmospheric pressure chemical ionization in the positive ion mode. Recoveries from spiked wheat were in the range of 80-106% at levels of 500 ppb. The limits of quantification for the whole method were between 10 and 100 ppb. Ion adduct formation with ammonium and acetate ions and MS(n) experiments provided information about substitution and fragmentation behavior of the mycotoxins. A scheme has been established for the partial structure elucidation of type A- and B-trichothecenes in fungal cultures. 相似文献
933.
K Nürnberg U Küchenmeister G Nürnberg K Ender W Hackl 《Archives of Animal Nutrition》1999,52(1):53-65
The effect of dietary n-3 fatty acids on the fatty acid composition and lipid peroxidation of different tissues in pigs were studied. 20 castrated male pigs were included in this investigation, one half was fed daily a diet containing 1.3 g n-3 fatty acids/kg diet (control) and 10 pigs were fed a diet containing 14 g n-3 fatty acids/kg diet (n-3 diet) at the growing-finishing period. The intake of dietary n-3 fatty acids increased the concentration of these fatty acids in backfat, and the neutral and polar fractions of skeletal muscle and heart homogenates. The polar fraction showed an increased relative concentration of n-3 fatty acids in comparison to control, while the n-6 fatty acid content was reduced. In heart homogenates there was an enlargement of n-3 fatty acids both in polar lipids and in neutral lipids whilst n-6 fatty acids were decreased. Feeding n-3 fatty acid enriched diet had no influence on meat quality parameters drip loss, meat colour or pH value. The lipid peroxidation (measured as malondialdehyde equivalents) was in the order liver > heart > skeletal muscle with higher values in the n-3 group. However, by stimulation of oxidation by Fe2+/ascorbate for 3 hours the order of oxidative products in the n-3 group was muscle > liver > heart, whereas in the control group the order was liver > heart = muscle. Summarized, feeding a highly n-3 fatty acid enriched diet caused an incorporation of these fatty acids and increased the susceptibility to peroxidation in all investigated tissues. 相似文献
934.
U Sch?nhusen J Voigt S C Lammers-Wienhoven J van Bruchem 《Archives of Animal Nutrition》1999,52(4):335-349
Sheep (Flemish female x Texel male, 55 kg BW), fitted with a PVC cannula in the dorsal rumen and single T-shaped PVC cannulas in the proximal duodenum, distal duodenum, mid-jejunum and terminal ileum were fed hay or hay-concentrate diets at various levels of nitrogen and cell walls (NDF) (22 to 32 g N/d; 150 to 699 g NDF/d). Co-EDTA and Cr-NDF were used as markers to measure the flow rate of digesta. Ribonucleic acid (RNA) intestinal digesta and in rumen bacteria was determined with orcinol after extraction with sodium chloride, precipitation with tungstophosphoric acid and alkaline hydrolysis. The RNA:total N ratio in bacteria, harvested from the rumen, amounted to 0.70 (CV 4.4%). The apparent digestibility of RNA in different sections of the intestine was higher than of total N. About 6% of RNA entering the duodenum disappeared between the proximal and distal duodenum. At jejunum, the net disappearance of RNA amounted to 68% of the quantity which entered the proximal duodenum. A higher result of 71% was obtained at the ileum. Total net disappearance of RNA between the proximal duodenum and rectum averaged 75%. Sixteen percent of RNA leaving the ileum was apparently digested in the large intestine. The true digestibility of RNA between the proximal duodenum and the terminal ileum, as estimated by multiple regression analysis, amounted to 78%. Of the amount of RNA entering the ileum, 24% was of endogenous origin. At ileum, the RNA passage was positively related to the ileal flow of NDF (R2 = 0.67) and N (R2 = 0.94). The passage of RNA increased by 3 mg RNA per g ileal indigestible NDF. Ileal endogenous N consisting of approximately 2% of endogenous RNA-N. In conclusion, the digestion capacity in the first part of the small intestine is high. Rising flows of indigestible cell walls and nitrogen increase the loss of ileal RNA. Further, using RNA as a microbial marker to assess the amount of microbial protein entering the duodenum of ruminants, digesta samples should be collected immediately post pylorus at the proximal duodenum, in order to avoid underestimation of the microbial protein synthesis in the rumen. 相似文献
935.
Lymphocyte beta -adrenoceptor downregulation in great danes with occult dilated cardiomyopathy (DCM) and with DCM and heart failure. 总被引:2,自引:0,他引:2
M Borgarelli P Badino L Bergamasco C Bussadori R Odore G Re A Tarducci U Dotta 《Veterinary journal (London, England : 1997)》1999,158(2):128-134
The importance of the adrenergic nervous system in supporting the failing heart has long been known. The adrenergic drive on cardiac structure and function has however some adverse effects, which include myocardial beta-adrenoceptor (beta-AR) downregulation and decreased beta-adrenergic responsiveness to cathecolamines. In dog lymphocytes, beta(1)-AR and beta(2)-AR populations are almost equally represented (with a slight prevalence of beta(2)) and a significant correlation between cardiac and lymphocytic adrenoceptors has been found. The aim of the present study was to investigate possible differences between the concentration of lymphocytic beta-AR in healthy dogs, dogs with dilated cardiomyopathy (DCM) and dogs with occult DCM. Three groups of great danes were considered: a control group (n =10), dogs with DCM (n =9) and dogs with occult DCM (n =4). Lymphocytic beta-AR populations were determined in all dogs. A substantial and significant decrease (P<0.05) in total-AR, beta(1)-AR and beta(2)-AR concentrations in the lymphocytes of dogs with symptomatic DCM and occult DCM compared to the control group was found. Although the mean value of the lymphocyte beta(1)-AR number in the asymptomatic group was double compared to the DCM group, this difference was not statistically significant. We conclude that in dogs beta-AR downregulation occurs early in the course of dilated cardiomyopathy. This finding may suggest the value of early use of a beta-blocker in the therapeutic regimen. Moreover, the continuous monitoring of lymphocytic beta-AR may represent a useful tool for the development of a more effective individual therapy. 相似文献
936.
Test of size-specific mass selection for Nile tilapia, Oreochromis niloticus L., cage farming in the Philippines 总被引:1,自引:0,他引:1
One generation of mass selection based on the collimation procedure (early culling of large fry) was applied on Nile tilapia, Oreochromis niloticus L., in net cages set in Laguna de Bay, Philippines. The objective was to test the effectiveness of a low-cost, small-scale broodstock improvement procedure in this culture environment. Directional selection was performed in two steps after initial removal of large fry at 21 days. Selection of parents and testing of the offspring were also conducted in hapa net cages set up in Laguna de Bay. The selection resulted in a significant positive response of 3% relative to the control, which represents a projected 34% gain over 5 years in Laguna cage culture. The realized heritability is ≈16%. 相似文献
937.
Rabbits infected with Trypanosoma brucei brucei (Basa isolate) were intraperitoneally administered with vitamins C and E at 100 mg/kg and 10 mg/kg body weight, respectively, from day 7 before infection to day 12 post-infection (p.i.). Another group of rabbits were similarly infected, but received no vitamin treatment. The uninfected (control) rabbits were either untreated or treated with vitamins like the infected group. Treatment of the infected animals did not affect the onset and level of parasitaemia. On day 12 p.i., the anaemia tended to be ameliorated, but insignificantly, by the treatment. The infection increased (p<0.05) serum urea and creatinine concentrations to similar levels in treated and untreated groups. However, the increase (p<0.05) in alanine and aspartate transaminases in the untreated infected animals was prevented in the treated infected ones. Therefore, it seemed that the treatment with antioxidant vitamins boosted their storage in hepatic cells, but not in erythrocytes and glomeruli, to annul any cellular injury due to infection. It is concluded that this may be an indirect evidence that the hepatic damage may be principally due to oxidative injury. 相似文献
938.
U Braun U Estermann K Feige T Sydler A Pospischil 《Journal of the American Veterinary Medical Association》1999,215(5):679-681
OBJECTIVE: To determine safety of lung biopsy in healthy cattle and compare 3 biopsy instruments for suitability of use. DESIGN: Prospective study. ANIMALS: 60 healthy cows. PROCEDURE: Bilateral lung biopsy through the ninth intercostal space was attempted in all cows. The procedure was performed with cows standing and restrained by an assistant. To study the short-term effects of lung biopsy, 50 cows were slaughtered 1 day after the procedure and examined. To study the long-term effects of lung biopsy, the remaining 10 cows were examined daily for 10 days and then slaughtered. Three biopsy instruments--the Autovac biopsy cannula, the Tru-Cut needle, and the Bard Biopty-System--were evaluated. RESULTS: 2 cows collapsed momentarily during the procedure but recovered quickly. The remaining cows did not develop adverse effects, and general attitude and condition were not affected. Postmortem examination of the 50 cows slaughtered 1 day after the procedure revealed lesions < or = 5.0 mm long and with a surface area < or = 4.0 mm2 at 108 of 154 (71%) biopsy sites involving the pulmonary pleura. Biopsy specimens were obtained during 48 of 50 (96%) procedures in which the Tru-Cut needle was used, during 38 of 39 (97%) procedures in which the Bard Biopty-System was used, and during only 1 of 11 biopsy procedures in which the Autovac cannula was used. At postmortem examination of the 10 cows slaughtered 10 days after the procedure, lesions were seen as small scars; adhesions were not observed. CONCLUSIONS AND CLINICAL RELEVANCE: Percutaneous lung biopsy is a safe procedure in healthy cows. 相似文献
939.
Emergence and recent evolution of canine parvovirus. 总被引:6,自引:0,他引:6
U Truyen 《Veterinary microbiology》1999,69(1-2):47-50
This review summarizes the current knowledge about the emergence of canine parvovirus from an ancestor virus similar to feline panleukopenia virus most likely from a wild carnivore host. The recent evolution of CPV, namely the emergence of new antigenic types, their biological properties and global distribution are also discussed. 相似文献
940.
实验利用鸭全血中单核细胞,粒细胞,血栓细胞及自然杀伤细胞对酵母细胞非特异性细胞毒性作用,检测了15日龄鸭胚到112日龄鸭非特异性细胞免疫的发生。实验结果表明,鸭胚孵出前1周的22日龄到孵出后3日龄是鸭非特异性细胞免疫的发生期;3 ̄112日龄鸭在正常的生理状态下非特异性细胞免疫水平没有明显的变化。 相似文献