In den vergangenen zwei Jahren wurden bei der DB AG mehrere Eisenbahnüberführungen als Netzwerkbogenbrücken errichtet. Die Bauweise zeichnet sich vor allem durch eine effektive, wirtschaftliche und ...ästhetische Tragkonstruktion aus. An den Bauwerksentwurf, die Ausführungsplanung und die Bauausführung sind aufgrund des komplexen Tragverhaltens und der schwierigeren Geometrie hohe Anforderungen zu stellen. Die Erfahrungen bei der Planung und dem Bau der Netzwerkbogenbrücken im Eisenbahnbrückenbau werden im nachfolgenden Aufsatz aufgeführt und anhand von Beispielen erläutert.
Experiences with Network arches for railway bridges. In the past two years several railroad bridges were established as Network arch bridges by DB AG. The construction method is characterized for the bridge construction particularly by an effective, an economical and aesthetically a carrying construction. Considering complex carrying behavior and more difficult geometry high demands on basic design, detailed design and construction works are to be made. The experiences when planning and building of the network arch bridges in the railway bridge construction are specified in the following article and described on the basis of examples.
To support the idea that Weismann's experiment constitutes a refutation of the Lamarckian hypothesis, Gauthier (1990) cited two chronologically disparate sources, Morgan (1925) and Merrell (1975). ...This article explores another source and concludes that this idea is more generally accepted and goes unchallenged. In addition, the article considers Weismann's original intent in docking the tails of mice, namely to test his own idea of the continuity of the germ plasm as opposed to Darwin's theory of pangenesis.
The Hiccup: Raison D'être Peter Gauthier
Bios (Madison, N.J.),
03/1991, Letnik:
62, Številka:
1/2
Journal Article
The hiccup, which consists of a sudden contraction of the diaphragm followed immediately by closure of the glottis, has no known function. This paper speculates on a mechanism whereby the hiccup is ...seen to assist in the movement of a food particle that has become lodged in the esophagus or is simply moving too slowly. Because of the vacuum created in the intrathoracic cage by the hiccup, it is thought that the esophagus below the particle could become dilated, and that this increase in the cross sectional area of the tube would then facilitate movement towards the stomach.
Since the publication of his book, Zoological Philosophy, in 1809, Jean Baptiste de Lamarck's name has been identified with the idea of the inheritance of acquired characteristics. In 1890, August ...Weismann put the idea to the test by cutting the tails off mice for many generations, and breeding each generation of amputees. This experiment has been viewed by some as the classic refutation of the Lamarckian position; a beautiful idea (Lamarck's) destroyed by an ugly fact (Weismann's experiment). This article questions the premise upon which these claims were made, and suggests that perhaps Weismann's experiment does not constitute a denial of Lamarck's hypothesis.
Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far ...remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin-a mammalian metal transporter-in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.
Targeted α therapy holds tremendous potential as a cancer treatment: it offers the possibility of delivering a highly cytotoxic dose to targeted cells while minimizing damage to surrounding healthy ...tissue. The metallic α-generating radioisotopes 225Ac and 227Th are promising radionuclides for therapeutic use, provided adequate chelation and targeting. Here we demonstrate a new chelating platform composed of a multidentate high-affinity oxygen-donating ligand 3,4,3-LI(CAM) bound to the mammalian protein siderocalin. Respective stability constants log β110 = 29.65 ± 0.65, 57.26 ± 0.20, and 47.71 ± 0.08, determined for the EuIII (a lanthanide surrogate for AcIII), ZrIV, and ThIV complexes of 3,4,3-LI(CAM) through spectrophotometric titrations, reveal this ligand to be one of the most powerful chelators for both trivalent and tetravalent metal ions at physiological pH. The resulting metal–ligand complexes are also recognized with extremely high affinity by the siderophore-binding protein siderocalin, with dissociation constants below 40 nM and tight electrostatic interactions, as evidenced by X-ray structures of the protein:ligand:metal adducts with ZrIV and ThIV. Finally, differences in biodistribution profiles between free and siderocalin-bound 238PuIV-3,4,3-LI(CAM) complexes confirm in vivo stability of the protein construct. The siderocalin:3,4,3-LI(CAM) assembly can therefore serve as a “lock” to consolidate binding to the therapeutic 225Ac and 227Th isotopes or to the positron emission tomography emitter 89Zr, independent of metal valence state.
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