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91.
Laurén A. Heinonen J. Koivusalo H. Sarkkola S. Tattari S. Mattsson T. Ahtiainen M. Joensuu S. Kokkonen T. Finér L. 《Water, air, and soil pollution》2009,196(1-4):251-261
Water, Air, & Soil Pollution - Estimates of increased nutrient export caused by forest clear-cuttings are mostly based on long-term paired catchment studies, where the treatment effect is... 相似文献
92.
Localization of the sheep FcRn in the mammary gland 总被引:5,自引:0,他引:5
Mayer B Zolnai A Frenyó LV Jancsik V Szentirmay Z Hammarström L Kacskovics I 《Veterinary immunology and immunopathology》2002,87(3-4):327-330
Among the multiple functions, which have been identified for the neonatal Fc receptor (FcRn), we study its role in the IgG transport in the mammary gland during the colostrum formation. For this reason, we have obtained several mammary gland biopsies from a pregnant sheep around parturition. The presence of the FcRn heavy chain mRNA was detected exclusively in the acinar and ductal epithelial cell by in situ hybridization (ISH). We detected strong signal in samples harvested 24 and 10 days prepartum; however, in samples we collected postpartum was barely detectable. Immunohistochemistry confirmed our ISH data. The cytoplasm of the epithelial cells of the acini and ducts in the mammary gland biopsies stained homogeneously before parturition, although a remarkable difference was observed in the pattern after lambing. The signal indicated uneven distribution of the FcRn alpha chain in the epithelial cells 1 and 5 days postpartum, since the apical sides of the epithelial cells were highlighted. The presence of the FcRn in the acinar and ductal epithelial cells and the obvious change of its distribution before and after parturition suggest that FcRn plays an important role in the IgG transport during colostrum formation. FcRn expression was also found in the lamb duodenal crypt epithelial cells, which have been previously demonstrated to secrete IgG1 in newborn ruminants, suggesting secretory role of the FcRn in ruminant epithelial cells. 相似文献
93.
94.
Twenty-seven weaned pigs with a wasting appearance were investigated. From a morphological point of view the pigs were divided into three groups. In the group of pigs with macro-scopical signs of regional ileitis, affected tissue showed substantial epithelial proliferation, and electron microscopic studies revealed the presence of microorganisms within the cytoplasm of the epithelial cells. There was a loss of, or only faint, enzymatic activity of alkaline phosphatase in the mucosal epithelium. In another group of five pigs there was no, or only slight, light microscopical signs of regional ileitis but presence of intracellular microorganisms. The enzymatic activity of the ileal epithelium was low. Low enzymatic activity of the ileal epithelium was observed in a third group of wasting pigs, which had no histological or electron microscopical signs of regional ileitis. 相似文献
95.
Lennart Eriksson 《Small-Scale Forestry》2004,3(1):1-15
Forestry in Sweden as well as in other European countries is characterised by intense and increasing international competition
resulting in decreasing roundwood prices in real terms. This is especially the situation in the mountainous region of Sweden
with long transportation distances between the felling site and the processing industries located at the coast. The question
arises whether forestry must be run more extensively than at present to achieve the optimal rate of silvicultural activities
compared with the amount of timber cut. With this in mind, optimising economic analyses have been performed at the stand level
as well as at the level of forest estates. Results of the analyses reveal that more intensive thinning (more frequent operations)
and shorter rotation periods would increase profit and offset continuously decreasing roundwood prices. Intensive pre-commercial
thinning (cleaning) is especially important for profitability of the subsequent thinnings and the final cut. The large number
of cuts during the rotation will increase logging costs. However, this will be more than offset by the increasing production
of economically matured dimensions of timber, an effect that will be still more pronounced when using new harvesting technology.
Moreover, frequent high thinning operations (thinning ‘from above’ or removal of dominant trees) will result in more dense
wood close to the pith, more evenly distributed year rings, and fewer and smaller knots in the lower part of the stem — in
other words more valuable roundwood which will justify high transportation costs. Several biological and technical aspects
of these treatment programs are discussed in the paper. 相似文献
96.
The possibility of using the Iosipescu shear test device to study the combined shear and compression behavior of anisotropic materials was examined. Measurements were made using both an original (Wyoming version) and an in-house modified Iosipescu shear and compression fixture. Numerical simulation of the combined shear and compression test was carried out to verify the reliability of the modified device. The numerical results were compared with data from experiments on a medium-density fiberboard. The numerical results show good agreement with the experimental results for the shear test in all the three material directions tested. The shapes as well as the values of the strain fields were similar in the numerical and experimental results. Different rotations of the combined shear and compression device were studied using the finite element method to find the combinations that gave reliable results in shear and compression. It was found that the 45° rotation gave the most uniform strain fields in the section between the notches. This rotation was tested on the fiberboard. 相似文献
97.
Anne-Mari Olsson Lennart Salmén Michaela Eder Ingo Burgert 《Wood Science and Technology》2007,41(1):59-67
In order to investigate the way in which fibre properties affect the mechano-sorptive creep phenomenon in paper, single wood
fibres were exposed to tensile stresses at a constant humidity of 80% relative humidity (RH) and in a cyclic humidity environment
varying between 80 and 30% RH. Contrary to earlier claims, it was demonstrated that single wood fibres exposed to a cyclic
RH show a considerably higher creep than that corresponding to the highest RH experienced in the cycle, i.e., a mechano-sorptive
behaviour. The creep strain rate at cyclic humidity was shown to be a function of the creep rate at constant climate, and
to be an apparent linear function of the applied stress. 相似文献
98.
During refining of mechanical pulp, a process occurring at high speed at temperatures of 140–160°C, the flexibility and bonding
ability of wood fibres are increased. To understand the mechanical behaviour of the fibres in this operation, deformations
at low speed of wet wood specimens at 50°C were studied under two different combinations of shear and compression loadings.
The results were compared with the behaviour of wet wood in pure compression. Some features of the deformation that occurred
in earlywood were analysed using an image analysis procedure. During pure compression the cell walls bend independently of
the shape of the fibre cells and their cell wall thickness. Under combined shear and compression, however, mainly the corners
of the fibre cells get deformed. In a second deformation performed in compression, the fibre cells follow the same deformation
pattern as given by the first deformation type whether in compression or in combined shear and compression. The interpretation
was that permanent defects in the cells themselves were introduced already in the first load cycle of the wood samples. The
load combination with lower shear gave the same permanent strain as the case of pure compression but using less energy. 相似文献
99.
Rainbow trout (Oncorhynchus mykiss) immune response towards a recombinant vaccine targeting the parasitic ciliate Ichthyophthirius multifiliis
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L von Gersdorff Jørgensen P W Kania K J Rasmussen A H Mattsson J Schmidt A Al‐Jubury A Sander A Salanti K Buchmann 《Journal of fish diseases》2017,40(12):1815-1821
The protective effect in rainbow trout (Oncorhynchus mykiss) of an experimental subunit vaccine targeting antigens in the parasite Ichthyophthirius multifiliis has been evaluated and compared to effects elicited by a classical parasite homogenate vaccine. Three recombinant parasite proteins (two produced in E. coli and one in insect cells) were combined and injected i.p., and subsequently, protection and antibody responses were analysed. Both the experimental and the benchmark vaccine induced partial but significant protection against I. multifiliis when compared to control fish. Specific antibody responses of vaccinated trout (subunit vaccine) were raised against one neurohypophysial n‐terminal domain protein #10 of three recombinant proteins, whereas the benchmark vaccine group showed specific antibody production against all three recombinant proteins. The immunogenic parasite protein #10 may be a potential vaccine candidate supplementing the protective I‐antigen in future vaccine trials. 相似文献
100.
Effect of biobed composition, moisture, and temperature on the degradation of pesticides 总被引:2,自引:0,他引:2
del Pilar Castillo M Torstensson L 《Journal of agricultural and food chemistry》2007,55(14):5725-5733
Biobeds retain and degrade pesticides through the presence of a biobed mixture consisting of straw, peat, and soil. The effects of biobed composition, moisture content, and temperature on pesticide degradation were investigated in laboratory studies. Straw produced the main microbial activity in the biobed mixtures as strong positive correlations were observed between straw, respiration, and phenoloxidase content. Most pesticides investigated were dissipated by cometabolic processes, and their dissipation was correlated with respiration and/ or phenoloxidase content. More pesticides were more dissipated at biobed moisture levels of 60% water holding capacity (WHC) than at 30% and 90% WHC, while 20 degrees C gave higher dissipation rates than 2 and 10 degrees C. A straw:peat:soil ratio of 50:25:25% v/v is recommended in field biobeds since this produces high microbial activity and low pH, favorable for lignin-degrading fungi and phenoloxidase activity. 相似文献