190 research outputs found
The Synthesis and polymerization of oxo-crown ethers
A novel synthetic route to and a polymn. procedure for oxo-crown ethers 2,11-dioxo-18-crown-6 (I), 2-oxo-12-crown-4 (II), and 2-oxo-21-crown-7 (III) are described. Cyclization, of the w-hydroxycarboxylic acid precursors of I-III was achieved by heating these precursors in the presence of a Lewis acid catalyst (CoCl2) and template salt (MCl). Cyclization yields ?82% were reached, using CsCl as template salt. Oxo-crown ethers I-III were polymd. using SnOct2 as catalyst, giving polymers with mol. wts. of approx. 5 kg/mol and dispersities of ca. 1.8 (measured with polyethylene oxide stds.). The polymn. of II was monitored with 1H-NMR and SEC giving information about the influence of monomer/catalyst ratio and temp. on polymn. rate as well as the influence of temp. on mol. wt. (distribution). The possibility of introducing end groups into II homopolymer using SnOct2-catalyzed polymn. was also studie
Samenvattingen Fusarium
An overview has been made on the theme of Fusarium with short summaries of research projects. Various topics are discussed. The titles of the summaries are: Dissection of lineage specific chromosomes in the onion pathogen Fusarium oxysporum f. sp. cepae and other emerging UK pathosystems; Differences in pre-harvest practices linked with the occurrence of Fusarium species and associated mycotoxins in maize from two ethnic groups in Vietnam; Biology, control and detection of Fusarium diseases in UK horticulture; Fusarium poae reduces Fusarium graminearum infection and mycotoxin production; European Union Reference Laboratory for mycotoxins & plant toxins in food and feed; Global epidemic of Panama disease on banana is caused by a new fungal species originating from Southeast Asia; Epidemiology of Fusarium in greenhouses
Adrenal vein sampling in a patient with primary hyperaldosteronism and severe contrast allergy
We report on a case of a 50-year-old female patient with primary hyperaldosteronism, in whom adrenal venous sampling was required to differentiate between unilateral and bilateral disease. Because of a history of severe allergy to iodinated contrast media, premedication with glucocorticoids was indicated. Exogenous glucocorticoids, however, can affect measurements of serum cortisol. To avoid this potential confounding effects on the cortisol assay, we decided to use dexamethasone instead of prednisolone or hydrocortisone. A high-dose adrenocorticotropin (ACTH) stimulation test with the simultaneous use of dexamethasone revealed an adequate adrenal cortisol response. ACTH-stimulated adrenal venous sampling showed reliable results, which provided a solid basis for further clinical decision-making.Diabetes mellitus: pathophysiological changes and therap
Deformation effects in Ni nuclei produced in Si+Si at 112 MeV
Velocity and energy spectra of the light charged particles (protons and
-particles) emitted in the Si(E = 112 MeV) + Si
reaction have been measured at the Strasbourg VIVITRON Tandem facility. The
ICARE charged particle multidetector array was used to obtain exclusive spectra
of the light particles in the angular range 15 - 150 degree and to determine
the angular correlations of these particles with respect to the emission angles
of the evaporation residues. The experimental data are analysed in the
framework of the statistical model. The exclusive energy spectra of
-particles emitted from the Si + Si compound system are
generally well reproduced by Monte Carlo calculations using spin-dependent
level densities. This spin dependence approach suggests the onset of large
deformations at high spin. A re-analysis of previous -particle data
from the Si + Si compound system, using the same spin-dependent
parametrization, is also presented in the framework of a general discussion of
the occurrence of large deformation effects in the A ~ 60 mass region.Comment: 25 pages, 6 figure
CO adsorption on neutral iridium clusters
The adsorption of carbon monoxide on neutral iridium clusters in the size
range of n = 3 to 21 atoms is investigated with infrared multiple photon
dissociation spectroscopy. For each cluster size only a single v(CO) band is
present with frequencies in the range between 1962 cm-1 (n = 8) and 1985 cm-1
(n = 18) which can be attributed to an atop binding geometry. This behaviour is
compared to the CO binding geometries on clusters of other group 9 and 10
transition metals as well as to that on extended surfaces. The preference of Ir
for atop binding is rationalized by relativistic effects on the electronic
structure of the later 5d metals
Special and inclusive education in the Republic of Ireland: reviewing the literature from 2000 to 2009
Provision for pupils with special educational needs in Ireland has undergone considerable change and review in the first decade of the twenty first century. In response to international demands for a more equitable education system which recognises diversity and considers how schools might address the needs of pupils who have been previously marginalised, Irish legislation has focused upon the development of inclusive schooling. Researchers during this period have endeavoured to understand how responses to the demand for greater inclusion have impacted upon the perceived need for change. This paper reviews the research literature for this period and identifies four key themes under which research has been conducted. The literature pertaining to these themes is explored and a possible agenda for future researchers identifie
Distinctive expansion of potential virulence genes in the genome of the oomycete fish pathogen Saprolegnia parasitica.
Oomycetes in the class Saprolegniomycetidae of the Eukaryotic kingdom Stramenopila have evolved as severe pathogens of amphibians, crustaceans, fish and insects, resulting in major losses in aquaculture and damage to aquatic ecosystems. We have sequenced the 63 Mb genome of the fresh water fish pathogen, Saprolegnia parasitica. Approximately 1/3 of the assembled genome exhibits loss of heterozygosity, indicating an efficient mechanism for revealing new variation. Comparison of S. parasitica with plant pathogenic oomycetes suggests that during evolution the host cellular environment has driven distinct patterns of gene expansion and loss in the genomes of plant and animal pathogens. S. parasitica possesses one of the largest repertoires of proteases (270) among eukaryotes that are deployed in waves at different points during infection as determined from RNA-Seq data. In contrast, despite being capable of living saprotrophically, parasitism has led to loss of inorganic nitrogen and sulfur assimilation pathways, strikingly similar to losses in obligate plant pathogenic oomycetes and fungi. The large gene families that are hallmarks of plant pathogenic oomycetes such as Phytophthora appear to be lacking in S. parasitica, including those encoding RXLR effectors, Crinkler's, and Necrosis Inducing-Like Proteins (NLP). S. parasitica also has a very large kinome of 543 kinases, 10% of which is induced upon infection. Moreover, S. parasitica encodes several genes typical of animals or animal-pathogens and lacking from other oomycetes, including disintegrins and galactose-binding lectins, whose expression and evolutionary origins implicate horizontal gene transfer in the evolution of animal pathogenesis in S. parasitica
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