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- Lange, D, et al.
(författare)
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Autocrine endothelial regulation in brain stem vessels of newborn piglets.
- 1999
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Ingår i: Histology and histopathology. - 0213-3911. ; 14:3, s. 821-5
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Tidskriftsartikel (refereegranskat)abstract
- Vasoactive intestinal peptide (VIP) is known as a potent regulator for the development of the central nervous system (CNS). The neonatal period of brain development is characterised by rapid cellular proliferation in parallel with neuronal differentiation and angiogenesis. We examined the expression of native VIP and the VIP receptor-associated protein by immunohistochemistry as well as the expression of VIP mRNA by in situ hybridisation in the brain stem of newborn piglets. We found both the mRNA and the protein of VIP as well as the VIP receptor-associated protein in endothelial cells of veins, arteries and capillaries in the marginal zone of brain stem tissue sections, especially in pons and mesencephalon, as well as in pial vessels. The coexpression of native VIP, VIP mRNA and the VIP receptor-associated protein within the endothelium suggests the presence of an autocrine loop, which has been detected so far only in neuroblastoma cells. This expression pattern gives evidence to the immaturity of endothelial cells at birth and the presence of an adaptive response in the VIP-regulated system during the change from intra- to extrauterine life.
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- Lange, J., et al.
(författare)
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Residual stress build-up in thermoset films cured below their ultimate glass transition temperature
- 1997
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Ingår i: Polymer. - 0032-3861. ; 38:4, s. 809-815
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Tidskriftsartikel (refereegranskat)abstract
- The stress build-up during isothermal cure below the ultimate glass transition temperature of epoxy and acrylate films is investigated in detail. Four systems are studied; two acrylates and two epoxies, with different crosslink densities. Relaxation modulus and film shrinkage are measured simultaneously during cure. The stress build-up is measured independently using a bi-layer beam bending technique. A model for the build-up of cure stresses is proposed, in which stresses are generated by the cure shrinkage and decay by viscoelastic relaxation. The relaxation is described by a simple, modified Maxwell model. Owing to the absence of memory in the Maxwell model, the resulting equation is simple and numerical stress computation straight-forward. The stress build-up over time is thus simulated for the four model systems based on the relaxation and shrinkage data, and the simulations compared with the experimentally observed stress build-up. The model successfully predicts the cure stresses where more standard elastic methods fail. It is found that the amount of stress build-up during cure varies greatly between the different systems. In general, a higher crosslink density results in higher stress build-up. The stress on cure ranged from less than 1% of the total stress on cure and cool-down in a lightly crosslinked epoxy to more than 30% of the total stress in densely crosslinked epoxies and acrylates. Finally simple approximations for estimating the stress levels after cure and cool-down from basic material properties, e.g. modulus and cure shrinkage, are proposed. © 1997 Elsevier Science Ltd. All rights reserved.
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- Michel, R, et al.
(författare)
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Cross sections for the production of residual nuclides by low- and medium-energy protons from the target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au
- 1997
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Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS. - : ELSEVIER SCIENCE BV. ; 129:2, s. 153-193
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- Cross sections for residual nuclide production by p-induced reactions were measured from thresholds up to 2.6 GeV using accelerators at CERN/Geneve, IPN/Orsay, KFA/Julich, LANL/Los Alamos, LNS/Saclay, PSI/Villigen, TSL/Uppsala, LUC/Louvain La Neuve. The t
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