137 research outputs found
Glycosylation of a CNS-specific extracellular matrix glycoprotein, tenascin-R, is dominated by O-linked sialylated glycans and "brain-type” neutral N-glycans
As a member of the tenascin family of extracellular matrix glycoproteins, tenascin-R is located exclusively in the CNS. It is believed to play a role in myelination and axonal stabilization and, through repulsive properties, may contribute to the lack of regeneration of CNS axons following damage. The contrary functions of the tenascins have been localized to the different structural domains of the protein. However, little is known concerning the influence of the carbohydrate conjugated to the many potential sites for N- and O-glycosylation (10-120% by weight). As a first analytical requirement, we show that >80% of the N-glycans in tenascin-R are neutral and dominated by complex biantennary structures. These display the "brain-type” characteristics of outer-arm- and core-fucosylation, a bisecting N-acetylglucosamine and, significantly, an abundance of antennae truncation. In some structures, truncation resulted in only a single mannose residue remaining on the 3-arm, a particularly unusual consequence of the N-glycan processing pathway. In contrast to brain tissue, hybrid and oligomannosidic N-glycans were either absent or in low abundance. A high relative abundance of O-linked sialylated glycans was found. This was associated with a significant potential for O-linked glycosylation sites and multivalent display of the sialic acid residues. These O-glycans were dominated by the disialylated structure, NeuAcα2-3Galβ1-3(NeuAcα2-6)GalNAc. The possibility that these O-glycans enable tenascin-R to interact in the CNS either with the myelin associated glycoprotein or with sialoadhesin on activated microglia is discusse
When local poverty is more important than your income: Mental health in minorities in inner cities
Volkswagen Foundation and the German Federal Ministry for Education and Research . Grant Number: BMBF 01 EL080
Ultrazvučne značajke bulbouretralnih žlijezda kunića (Oryctolagus cuniculus).
The aim of the study was to describe some of the ultrasonographic features of domestic rabbit bulbourethral glands, with regard to their relevance to reproductive pathology. The glands of ten sexually mature, clinically healthy, white, male New Zealand rabbits, aged 18 months, with body masses ranging from 2.8-3.2 kg, were investigated following anaesthesia. A perineal sonographic approach was applied. The glands were observed in two planes. They were viewed sonographically as solid, hyperechoic, heterogeneous structures. A hyperechoic gland without a hypoechoic center was visualized in sagittal section. In transverse section, normal bulbourethral glands were visualized dorsolaterally to the bulbar urethra, and a hypoechoic urethra was located ventromedially. As part of the study, the sonographic features of the bulbourethral glands were compared in a liquid isotonic medium. The analogous results of both methods allowed us to propose the use of perineal ultrasonography as a sufficiently definitive, non-invasive method for visualizing rabbit bulbourethral glands.Cilj ovog istraživanja bio je opisati neke ultrazvučne značajke bulbouretralnih žlijezda kunića s obzirom na njihovu važnost u patologiji spolnih organa. Nakon anestezije bile su pretražene žlijezde 10 spolno zrelih, klinički zdravih kunića bijele novozelandske pasmine u dobi od 18 mjeseci, tjelesne mase 2,8 - 3,2 kg. Ultrazvučna pretraga obavljena je u perinealnom području. Žlijezde su bile pretražene u dvije ravnine. Ultrazvučno su se vidjele kao dvije hiperehogene solidne, heterogene tvorevine. Hiperehogena žlijezda bez hipoehogenog centra bila je uočljiva na sagitalnoj ravnini. U poprječnoj ravnini normalne bulbouretralne žlijezde uočavale su se dorzolateralno od bulbarne uretre, a hipoehonogena uretra bila je smještena ventromedijalno.Ultrazvučne značajke bulbouretralnih žlijezda bile su uspoređivane u odnosu na izotonični tekući medij. Na osnovi postignuća sličnih rezultata dvjema metodama može se predložiti perinealni ultrazvučni pristup kao primjerena neinvazivna metoda za vizualizaciju bulbouretralnih žlijezda kunića
Resonance ionization of sputtered atoms-progress toward a quantitative technique
The combination of RIMS and ion sputtering has been heralded as the ideal means of quantitatively probing the surface of a solid. While several laboratories have demonstrated the extreme sensitivity of combining RIMS with sputtering, less effort has been devoted to the question of accuracy. Using the SARISA instrument developed at Argonne National Laboratory, a number of well-characterized metallic
samples have been analyzed. Results from these determinations have been compared with data obtained by several other analytical methods. One significant finding is that impurity measurements down to ppb levels in metal matrices can be made quantitative by employing polycrystalline metal foils as calibration standards. This discovery substantially reduces the effort required for quantitative analysis since a single standard can be used for determining concentrations spanning nine orders of magnitude
Synthesis, characterisation and luminescent properties of lanthanide-organic polymers with picolinic and glutaric acids
Three new lanthanide(III) complexes (Ln = Sm, Tb and Eu)
of picolinic and glutaric acid were prepared and characterised.
The crystal structure of the complex [Sm(glu)(pic)-
(H2O)2] (where Hpic and H2glu stand for picolinic and glutaric
acid, respectively) was determined by single-crystal Xray
diffraction. All the Ln complexes were characterised by
elemental analysis, infrared spectroscopy, X-ray powder diffraction
and thermoanalytical measurements. The combined
Introduction
The design of functional units from the molecular scale
to macroscopic assemblies has emerged as a new paradigm
in materials synthesis resulting in an interplay between conventional
molecular chemistry and conventional solid-state
science. This has been particularly clear in the development
of functional materials using coordination compounds such
as in the field of semiconductors technology, supramolecular
machinery, microporous and hybrid materials and catalysis.[
1] In some cases, the development of these functional
materials is based on the chemistry of well-known coordination
compounds as illustrated by the assembly of inorganic-
organic extended lattices[2] and in the thermolysis of
metal thiolato compounds to produce thin films or nanoparticles.[
3]
Metals coordinated to aromatic ambidentate ligands
form a class of compounds with a wide variety of coordination
modes which has long attracted the attention of chemists.[
4] Griffith and co-workers extended this type of chemistry
to the second row transition metals and, in particular,
[a] Department of Chemistry, University of Aveiro, CICECO,
3810-193 Aveiro, Portugal
Fax: +351-234-370-084
E-mail: [email protected]
[b] Department of Physics, University of Aveiro, CICECO,
3810-193 Aveiro, Portugal
[c] Department of Chemistry, University of Cambridge,
Lensfield Road, CB2 1EW Cambridge, United Kingdom
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
© 2007 Wiley-VCH Verlag 4238 GmbH & Co. KGaA, Weinheim Eur. J. Inorg. Chem. 2007, 4238–4246
data show that these Ln complexes are isostructural. The effect
of both organic ligands on the photoluminescent behaviour
of the Sm3+, Eu3+ and Tb3+ complexes is discussed and
we anticipate the possibility of controlling the photoluminescence
of picolinic-containing lanthanide compounds by systematically
varying the length of the bridging ligand.FCT - POCI/QUI/58377/2004Grant - SFRH/BD/17968/2004Grant - SFRH/BPD/14954/ 200
Oxygen adsorption on the Ru (10 bar 1 0) surface: Anomalous coverage dependence
Oxygen adsorption onto Ru (10 bar 1 0) results in the formation of two
ordered overlayers, i.e. a c(2 times 4)-2O and a (2 times 1)pg-2O phase, which
were analyzed by low-energy electron diffraction (LEED) and density functional
theory (DFT) calculation. In addition, the vibrational properties of these
overlayers were studied by high-resolution electron loss spectroscopy. In both
phases, oxygen occupies the threefold coordinated hcp site along the densely
packed rows on an otherwise unreconstructed surface, i.e. the O atoms are
attached to two atoms in the first Ru layer Ru(1) and to one Ru atom in the
second layer Ru(2), forming zigzag chains along the troughs. While in the
low-coverage c(2 times 4)-O phase, the bond lengths of O to Ru(1) and Ru(2) are
2.08 A and 2.03 A, respectively, corresponding bond lengths in the
high-coverage (2 times 1)-2O phase are 2.01 A and 2.04 A (LEED). Although the
adsorption energy decreases by 220 meV with O coverage (DFT calculations), we
observe experimentally a shortening of the Ru(1)-O bond length with O coverage.
This effect could not be reconciled with the present DFT-GGA calculations. The
nu(Ru-O) stretch mode is found at 67 meV [c(2 times 4)-2O] and 64 meV [(2 times
1)pg-2O].Comment: 10 pages, figures are available as hardcopies on request by mailing
[email protected], submitted to Phys. Rev. B (8. Aug. 97), other related
publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm
Structure determination of an adsorbate-induced multilayer reconstruction: (1×2)-H/Ni(110)
The reconstructed (1×2) structure formed by saturation of a Ni(110) surface with adsorbed H atoms at T<180 K was investigated by LEED. Excellent agreement between experimental and calculated I-V spectra for eleven nonequivalent beams was obtained for a model in which parallel rows of Ni atoms in the topmost layer are laterally shifted by 0.3 Å (‘‘row pairing’’) and which exhibits periodic vertical displacements (‘‘buckling’’) of the atoms in the second layer
How is agroforestry perceived in Europe? An assessment of positive and negative aspects by stakeholders
Whilst the benefits of agroforestry are widely recognised in tropical latitudes few studies have assessed how agroforestry is perceived in temperate latitudes. This study evaluates how stakeholders and key actors including farmers, landowners, agricultural advisors, researchers and environmentalists perceive the implementation and expansion of agroforestry in Europe. Meetings were held with 30 stakeholder groups covering different agroforestry systems in 2014 in eleven EU countries (Denmark, France, Germany, Greece, Hungary, Italy, Netherlands, Portugal, Spain, Sweden and the United Kingdom). In total 344 valid responses were received to a questionnaire where stakeholders were asked to rank the positive and negative aspects of implementing agroforestry in their region. Improved biodiversity and wildlife habitats, animal health and welfare, and landscape aesthetics were seen as the main positive aspects of agroforestry. By contrast, increased labour, complexity of work, management costs and administrative burden were seen as the most important negative aspects. Overall, improving the environmental value of agriculture was seen as the main benefit of agroforestry, whilst management and socio-economic issues were seen as the greatest barriers. The great variability in the opportunities and barriers of the systems suggests enhanced adoption of agroforestry across Europe will be most likely to occur with specific initiatives for each type of system
R-Allyl Nickel(II) Complexes with Chelating N-Heterocyclic Carbenes: Synthesis, Structural Characterization, and Catalytic Activity
The N-heterocyclic carbene (NHC) nickel complexes [(L)Ni(NHC)][BArF4] (ArF = 3,5-bis(trifluoromethyl)-
phenyl; L = allyl (1), methylallyl (2); NHC = 1-(2-picolyl)-3-methylimidazol-2-ylidene (a), 1-(2-picolyl)-3-isopropylimidazol-2-ylidene (b), 1-(2-picolyl)-3-n-butylimidazol-2-ylidene (c), 1-(2-picolyl)-3-phenylimidazol-2-ylidene (d), 1-(2-picolyl)-3- methylbenzoimidazol-2-ylidene (e), 1-(2-picolyl)-4,5-dichloro-3-methylimidazol-2-ylidene (f)) have been obtained in high yields and characterized by NMR spectroscopy. Furthermore, 1d was unambiguously characterized by single-crystal X-ray crystallography. Complexes 1a−f/2a−f have shown catalytic activity toward dimerization and hydrosilylation of styrenes. In particular, 1a proved to be the most efficient catalyst in the dimerization of styrene derivatives in the absence of cocatalyst. Also, complexes 1a,d showed high selectivity and moderate to good yields in hydrosilylation reactions
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