Magnetic resonance imaging methods to reveal the real-time distribution of nickel in porous media   总被引：1，自引：0，他引：1  

A. B. Moradi    S. E. Oswald    J. A. Massner    K. P. Pruessmann    B. H. Robinson  & R. Schulin 《European Journal of Soil Science》2008,59(3):476-485

Direct and non‐destructive measurement of the sorption, diffusion and mobility of ions and molecules in porous media has applications in industry and environmental science. We used magnetic resonance imaging (MRI) to visualize the dynamic distribution of paramagnetic nickel (Ni⁺²) ions in porous media. Various MRI sequences were tested to image Ni²⁺ at small concentrations. Noisy gradient echo images had poor contrast between samples containing various Ni²⁺ concentrations. Turbo spin echo and spoiled gradient echo images showed a linear relation between Ni²⁺ concentrations and signal intensity over a wide range of concentrations. Spoiled gradient echo images resolved Ni²⁺ concentrations (down to 30 mg litre^?1) better than turbo spin echo images. However, for smaller concentrations, uncertainty in intensity values increased. A T₁ measurement, obtained using an inversion recovery sequence, showed a linear correlation between T₁ and Ni²⁺ concentration down to 1.5 mg litre^?1. In a glass bead medium with an ion exchange resin as an Ni sink, the real‐time development of the Ni²⁺ depletion zone around the resin, as Ni was sorbed into the resin, was imaged by T₁ mapping. A spatial resolution of 0.58 mm and a temporal resolution of less than a minute were achieved. The two‐dimensional Ni²⁺ gradient that was determined from MRI agreed well with geochemical modelling results. The results of this study showed that MRI, in particular T₁ mapping, can quantify microscale behaviour of paramagnetic species in porous media. However, ferromagnetic components that naturally occur in most soils can easily disturb the MRI signal.  相似文献   

Individual tree and stand-level carbon and nutrient contents across one rotation of loblolly pine plantations on a reclaimed surface mine     

Angel  Hannah Z.  Priest  Jeremy S.  Stovall  Jeremy P.  Oswald  Brian P.  Weng  Yuhui  Williams  Hans M. 《New Forests》2019,50(5):733-753

New Forests - While reclaimed loblolly pine (Pinus taeda L.) plantations in east Texas, USA have demonstrated similar aboveground productivity levels relative to unmined forests, there is interest...  相似文献   

Changes in performance,blood parameters,humoral and cellular immune responses in weanling piglets exposed to low doses of aflatoxin   总被引：4，自引：0，他引：4  

Marin DE  Taranu I  Bunaciu RP  Pascale F  Tudor DS  Avram N  Sarca M  Cureu I  Criste RD  Suta V  Oswald IP 《Journal of animal science》2002,80(5):1250-1257

A feeding trial was conducted to evaluate the effect of aflatoxin (AF)-contaminated diets on growth and hematological and immunological parameters. Low doses of aflatoxins (140 and 280 ppb) were included in a corn-soybean diet provided for ad libitum consumption to 36 weanling piglets for a period of 4 wk. A "dose-related" decrease in weight gain was observed in treated animals. This effect was significant (P < 0.05) in the 280 ppb-treated group compared to the control group. Ingestion of AF-contaminated feed at either level had no effect on total red blood cell numbers or on their relative number of lymphocytes, monocytes, neutrophils, basophils, and eosinophils in blood. Likewise, AF did not alter globulin, albumins, or total protein concentrations in serum, nor did AF alter the expression of regulatory cytokines produced by either Th1 (IL-2) or Th2 (IL-4) lymphocyte subsets in phytohemagglutinin-stimulated blood samples. By contrast, AF had a biphasic effect on total white blood cell number; the low dose of AF (140 ppb) decreased the total number of white blood cells, whereas the high dose (280 ppb) had the opposite effect. Consumption of AF also increased the concentration of gamma-globulin in the serum. A reduced immune response induced by Mycoplasma agalactiae in the 280-ppb-treated group was also observed. Cytokine mRNA expression in phytohemagglutinin-stimulated blood cells indicated that AF decreased proinflammatory (IL-1beta, TNF-alpha) and increased anti-inflammatory (IL-10) cytokine mRNA expression. These results demonstrate that low doses of AF depress growth and alter many aspects of humoral and cellular immunity in pigs.  相似文献   

Up-regulation by feline interleukin-4 and down-regulation by feline interferon-gamma of major histocompatibility complex class II on cat B-lymphocytes     

Gomes-Keller MA  Nunez R  Schroff M  Oswald D  Willett BJ  Lutz H 《Veterinary immunology and immunopathology》2002,88(3-4):197-208

  相似文献   

Acetylcholine receptor synthesis in retina and transport to optic tectum in goldfish   总被引：4，自引：0，他引：4  

J M Henley  J M Lindstrom  R E Oswald 《Science (New York, N.Y.)》1986,232(4758):1627-1629

Previous studies have suggested that the retinotectal system of the goldfish contains a nicotinic acetylcholine receptor (nAChR) that is sensitive to alpha-bungarotoxin. Extracellularly recorded field potentials elicited in response to visual stimulation can be blocked by alpha-bungarotoxin, and alpha-bungarotoxin can interfere with the maintenance of retinotectal synaptic connections. Whether the transmission between the retinal ganglion cells and the tectal cells is mediated by acetylcholine and whether nAChR's exist on the dendrites of tectal cells are questions that remain. The experiments described in this report were designed to determine the site of synthesis of the nAChR's associated with the goldfish retinotectal projection. Radioactive (35S-labeled) methionine was injected into either the eye or the tectal ventricle, and the incorporation of radioactivity into the nAChR was measured by immunoprecipitation. The use of this technique provides evidence that an nAChR associated with the goldfish retinotectal projection is synthesized in the retina and transported to the optic tectum, which suggests a presynaptic site of acetylcholine action on retinal terminals.  相似文献   

Ecological, political and social challenges of prescribed fire restoration in east Texas pineywoods ecosystems: a case study     

Rideout  Sandra; Oswald  Brian P.; Legg  Michael H. 《Forestry》2003,76(2):261-269

  相似文献   

Reorganisation of wood production for improved performance: a swiss forest district case study     

Oswald  Kaspar  Riechsteiner  Denis  Thees  Oliver  Lemm  Renato 《Small-Scale Forestry》2004,3(2):143-160

An extremely fragmented timber supply, high harvesting costs, low profitability, high subsidies and insufficient competitiveness characterise forest enterprises in Switzerland. In a case study using a forest district in the state of Solothurn as an example, it was sought to identify strengths and weaknesses of wood production and to formulate possible improvement opportunities. The results indicate that there is considerable potential for industry rationalisation. The greatest handicaps are the small sized forest holdings, excessive numbers of staff, insufficient use of modern harvesting technology and costly business administration. The most eminent of the proposed improvement measures are those which aim to increase concentration of timber supplies and reduce production costs. These include greater centralising of timber sales as well as planning and steering of production, making full use of modern harvesting systems, reducing transaction costs, supporting administration, planning and steering of wood production with modern information technology and reducing input on stand tending. In principle, amelioration can be best achieved by close cooperation with neighbours or even merger of enterprises. Consequently, there is a need for related business tasks to be combined in functions. The paramount prerequisite for success is the willingness and readiness of all affected stakeholders to make changes. The situation described is typical for Swiss forestry and the proposed solutions could well be used as models for a wide range of Swiss forest districts.  相似文献   

Diagnosis of feline leukaemia virus infection by semi-quantitative real-time polymerase chain reaction     

Pinches MD  Helps CR  Gruffydd-Jones TJ  Egan K  Jarrett O  Tasker S 《Journal of Feline Medicine and Surgery》2007,9(1):8-13

In this paper the design and use of a semi-quantitative real-time polymerase chain reaction assay (RT-PCR) for feline leukaemia virus (FeLV) provirus is described. Its performance is evaluated against established methods of FeLV diagnosis, including virus isolation and enzyme-linked immunoassay (ELISA) in a population of naturally infected cats. The RT-PCR assay is found to have both a high sensitivity (0.92) and specificity (0.99) when examined by expectation maximisation methods and is also able to detect a large number of cats with low FeLV proviral loads that were negative by other conventional test methods.  相似文献   

Effects of added fermentable carbohydrates in the diet on intestinal proinflammatory cytokine-specific mRNA content in weaning piglets     

Pié S  Awati A  Vida S  Falluel I  Williams BA  Oswald IP 《Journal of animal science》2007,85(3):673-683

  相似文献   

Enterohaemorrhagic Escherichia coli: emerging issues on virulence and modes of transmission   总被引：5，自引：0，他引：5  

Caprioli A  Morabito S  Brugère H  Oswald E 《Veterinary research》2005,36(3):289-311

Enterohaemorrhagic Escherichia coli (EHEC) constitute a subset of serotypes (E. coli O157 and some other serogroups) of Shiga toxin (Stx)-producing E. coli (STEC) firmly associated with severe human illnesses like bloody diarrhoea and haemolytic uraemic syndrome. Stx production is essential but not sufficient for EHEC virulence. Most strains are capable of colonising the intestinal mucosa of the host with the "attaching and effacing" mechanism, genetically governed by a large pathogenicity island (PAI) defined as the Locus of Enterocyte Effacement. Other virulence factors carried by mobile genetic elements like PAI and plasmids have been recently described, and their role in the pathogenic process has not been fully elucidated. EHEC are zoonotic pathogens. They rarely cause disease in animals, and ruminants are recognised as their main natural reservoir. Cattle are considered to be the most important source of human infections with EHEC O157, and the ecology of the organism in cattle farming has been extensively studied. The organism has also been reported in sheep, goats, water buffalos, and deer. Pigs and poultry are not considered to be a source of EHEC and the sporadic reports may derive from accidental exposure to ruminant dejections. The epidemiology of EHEC infections has remarkably changed during the past ten years and an increasing number of unusual food vehicles have been associated with human infections. New routes of transmission have emerged, like contact with animals during farm visits and a wide variety of environment-related exposures. As for other zoonotic agents, having animals and raw products that are free from EHEC is not possible in practice. However, their occurrence can be minimised by applying high standards of hygiene in all the steps of the food production chain.  相似文献