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[en] Elastic scattering factors (or atomic form factors) f(s) for Li to Ar have been derived in the first Born approximation from ab initio MR-SDCI (multireference singly and doubly excited configuration interaction) calculations which recover between 90 and 99% of the estimated total correlation energy. The correlation effects on f(s) are contrasted with the relativistic effects known from the literature. Atomic form factors are presented that take into account correlation and relativistic contributions in an additive manner. (orig.)
Journal
Acta Crystallographica. Section A: Foundations of Crystallography; ISSN 0108-7673; 
; CODEN ACACEQ; v. 51(2); p. 171-177
; CODEN ACACEQ; v. 51(2); p. 171-177
[en] The title compound has been prepared from YbBr3 and NaN(SiMe3)2 in THF suspension, forming yellow single crystals from hexane solutions which were characterized by a crystal structure determination. Space group P anti 1, Z = 2, lattice dimensions at -100 C: a = 1085.4(1), b = 1410.2(1), c = 1912.0(1) pm; α = 78.62(1) , β = 80.61(1) , γ = 73.45(1) , R = 0.025. In the molecular structure of [Yb3OBr4{N(SiMe3)2}3(THF)3[ the three ytterbium atoms together with the μ3-oxygen atom and a μ3-bromine atom form a distorted trigonal bipyramid. In addition, three μ2-Br atoms coordinate the Yb atoms in the equatorial plane, whereas the THF molecules and the N(SiMe3)-2 ligands are terminally coordinated, thus forming a distorted octahedrally surrounding of the Yb atoms. (orig.)
Journal
Zeitschrift fuer Anorganische und Allgemeine Chemie (1950); ISSN 0044-2313; ; CODEN ZAACAB; v. 623(8); p. 1203-1204
; CODEN ZAACAB; v. 623(8); p. 1203-1204
[en] Hf2Te was prepared by arc-melting appropriate compressed mixtures of HfTe2 and hafnium. The structure of the new hafnium-rich telluride was determined by means of powder diffractometry, RB=0.0565. Hf2Te adopts a Nb2Se-type structure, monoclinic, space group C2/m, Z=8, Pearson symbol mS24, a=1516.3(2) pm, b=370.26(4) pm, c=1006.4(1) pm, β=90.50(1) . The structure comprises pairwise interpenetrating columns of trans-face-shared centred Hf9 cuboids. The columns form puckered slabs which are interconnected by homo- and heteronuclear bonds. Tellurium atoms are one-sidedly coordinated by six hafnium atoms. The coordination configurations about the two distinct tellurium atoms represent Hf6Te hypho-fragments of a tri-capped trigonal prismatic Hf9Te closo-cluster. Characteristic features of four other M2Q structure types are elucidated. The valence electron concentration available for metal-metal bonding together with the cohesive energy of the respective metal are found to control the formation of the various M2Q metal partial structures. (orig.)
Journal
[en] The tetrachlorides of zirconium and hafnium react with excess phosphaneimine Me3SiNPMe3 at 220 C in the presence of sodium fluoride by cleaving FSiMe3 to form the ionic complexes [Zr3Cl6(NPMe3)5]+[Zr2Cl6(NPMe3)3]- and [Hf3Cl6(NPMe3)5]+[Hf2Cl7(NPMe3)2]-. According to crystal structure analyses in the cations the three metal atoms together with three μ2-NPMe3- groups and two NPMe3- groups with μ3-function are forming trigonal bipyramids. In the anion of the zirconium complex the Zr atoms are linked by three μ2-N bridges, whereas in the anion of the hafnium compound bridging is effected by two μ2-N bridges and one μ2-Cl bridge. Primary products in the reaction of MCl4 (M = Zr, Hf) with silylated phosphaneimines are donor-acceptor complexes like [ZrCl4(Me3SiNPPh3)] which has been characterized crystallographically as an example. In the molecular complex the Zr-atom is coordinated in a trigonal bi-pyramidal fashion. (orig.)
Journal
Zeitschrift fuer Anorganische und Allgemeine Chemie (1950); ISSN 0044-2313; ; CODEN ZAACAB; v. 623(2); p. 224-230
; CODEN ZAACAB; v. 623(2); p. 224-230
[en] Batch-experiments were carried out to examine the influence of EDTA and NTA on sorption and desorption of ions of the heavy metals copper and lead onto the surface of natural river sediments. The results show that sorption of copper is strongly hindered by EDTA and NTA. This effect increases linearly with the amount of complexing agent used. Within the selected range of concentration the desorbing effect of EDTA and NTA on previously sorbed ions of copper and lead is also quite strong. In fact, less amounts of metal than calculated were desorbed. The results of the desorption-experiments show that the strength of the amount of metal-ion binding to the surface of sediments varies. At the beginning of the desorbing-process the increase of released metal-ions rises more than afterwards. (orig.)
[de]
Zur Untersuchung des Einflusses von EDTA und NTA auf die Sorption von Ionen der Schwermetalle Kupfer und Blei an natuerliche Flusssedimente wurden in Batch-Versuchen Sorptions- und Desorptionsexperimente durchgefuehrt. Das Ergebnis zeigt, dass EDTA und NTA die Sorption von Kupferionen stark behindern. Die sorptionshindernde Wirkung ist dabei linear abhaengig von der eingesetzten Menge an Komplexbildern. Die desorbierende Wirkung von EDTA und NTA ist bei den eingesetzten Komplexbildnermengen ebenfalls gross. Insgesamt koennen aber stets weniger Metallionen freigesetzt werden, als rechnerisch zu erwarten ist. Dies bedeutet, dass Metallionen unterschiedlich stark an die Sedimentoberflaeche gebunden werden. Der zeitliche Ablauf der Desorption zeigt besonders in der Anfangsphase einen starken Anstieg der freigesetzten Metallionenmenge. (orig.)Source
Gesellschaft Deutscher Chemiker, Karlsruhe (Germany). Fachgruppe Wasserchemie; 508 p; ISBN 3-527-28566-0; ; 1993; p. 387-396; VCH Verlagsges; Weinheim (Germany)
; 1993; p. 387-396; VCH Verlagsges; Weinheim (Germany)
[en] Venous compression is a clinical entity distinct from deep vein thrombosis although the clinical signs may be indistinguishable. Reasons for venous compression are tumors, scars, hematomas, postoperative changes and anatomic variations. The differential diagnosis between compression and thrombosis is important because therapy and prognosis differ markedly between the two patient groups. Ultrasound, computed tomography and magnetic resonance tomography are the diagnostic tools of choice because they offer not only information about the intraluminal situation but also about the extraluminal pathology. (orig.)
[de]
Venoese Kompressionssyndrome sind durch externe Kompression des venoesen Leitsystems bedingte Abflussstoerungen, die klinisch primaer nur schwer von thrombotischen Abflusshindernissen unterscheidbar sind. Ursachen fuer eine venoese Kompression sind tumoroese Raumforderungen, Narben, Haematome, postopertive Veraenderungen und funktionelle Engen. Die Kenntnis des venoesen Kompressionssyndroms als Differentialdiagnose zur Venenthrombose ist wichtig, da sich die Therapie und Prognose dieser Patientengruppen deutlich voneinander unterscheiden. Da die Ursachen der Kompressionssyndrome extravasaler Natur sind, bieten sich zur diagnostischen Abklaerung vorwiegend Schnittbildverfahren an. (orig.)Journal
[en] The following studies were designed to quantify changes in tracheal mucus secretion and epithelial proliferation of peripheral airways induced by inhaled NO2 and SO2. Groups of male Sprague-Dawley rats were exposed alternatively to 1, 5, 10 and 20 ppm NO2 and SO2 the exposure-time being 3 or 25 days (d) respectively. Studies of tracheal mucus secretion radiolabelling mucins with 35S clearly demonstrated a concentration dependant modulation of mucus secretion. We were able to demonstrate for the first time a significant increase of mucus secretion due to submucosal application of the peptide hormone GLP-1(7-36)amide. We were able to demonstrate amylin to be a potent secretagogue, dose-dependently stimulating mucus secretion. Our morphologic data reveal the effects caused by concentrations between 4-5 ppm NO2 to be so small, that they are hardly detectable at light microscopic level. The assessment of proliferative activity, however, clearly demonstrates an increased proliferation due to even lower concentrations indicating, that even 1 ppm is able to cause epithelial impairment with consecutive regeneration. Double-labelling techniques of proliferation markers and the 10 kD Clara cell specific antigen reveal the Clara cell to be the only source for epithelial regeneration in peripheral airways under the reported experimental conditions of this study. (orig.)
[de]
In der vorliegenden Arbeit wurden quantitative Untersuchungen der trachealen Muzinsekretion sowie der epithelialen Proliferation der peripheren Atemwege durch inhalative Aufnahme der beiden Noxen NO2 und SO2 durchgefuehrt. Hierzu wurden Gruppen maennlicher Sprague-Dawley-Ratten gegenueber 1, 5, 10 und 20 ppm NO2 oder SO2 ueber einen Zeitraum von 3 oder 25 Tagen (d) exponiert. Studien der trachealen Muzinsekretion mittels radioaktiver Markierung der Muzine mit 35S zeigten eine konzentrationsabhaengige Modulation der Sekretion. Bei submukoeser Applikation konnte erstmals mit GLP-1(7-36)amid eine signifikante Stimulation der Muzinsekretion nachgewiesen werden. Wir konnten zeigen, dass Amylin bei submukoeser Gabe eine starke dosisabhaengige tracheale Mukussekretion bewirkt. Unsere morphologischen Daten zeigen, dass im Bereich von etwa 4-5 ppm NO2 die Grenze der Expositionsdosis liegt, deren Effekt noch durch die reine lichtmikroskopische Untersuchung nachweisbar ist. Durch die Proliferationsanalyse laesst sich jedoch erkennen, dass eine signifikante Erhoehung der Proliferation des Atemwegsepithels bereits bei wesentlich geringeren Dosen eintritt. Die Doppelmarkierung von Proliferationsmarkern auf der einen Seite und dem 10kD Clarazell-spezifischen Antigen auf der anderen Seite erlauben die Identifikation der Clarazelle als der einzigen Quelle der epithelialen Regeneration innerhalb der peripheren Atemwege unter den fuer die vorliegenden Studien gewaehlten Versuchsbedingungen. (orig.)Source
Oct 1995; 93 p; ISSN 0940-3000; ; FOERDERKENNZEICHEN PUG L 92006
; FOERDERKENNZEICHEN PUG L 92006
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