bluuebunny/crossref_metadata_2025 huggingface dataset:
Lasteinleitung bei ausbetonierten Hohlprofil‐Verbundstützen
Authors: Hanswille Gerhard , Porsch Markus
Published: October 2004

Verbundstützen aus ausbetonierten Hohlprofilen werden seit einigen Jahren verstärkt im Geschoß‐ und Hochhausbau eingesetzt. Die Wirtschaftlichkeit wird dabei in hohem Maße durch die Ausbildung der Krafteinleitungsbereiche bestimmt. Es wird über neuere Forschungsarbeiten und umfangreiche experimentelle Untersuchungen berichtet, die die Umschnürungswirkung des Stahlrohres im Lasteinleitungsbereich wesentlich stärker als bisher berücksichtigen. Die entwickelten Modelle stellen die Grundlage für die Bemessungsregeln für Lasteinleitungsbereiche von Hohlprofil‐Verbundstützen in prEN 1994‐1‐1 und DIN 18800‐5 dar. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rotationskapazität nachgiebiger Stahlknoten
Authors: Kuhlmann Ulrike , Kühnemund Frank
Published: October 2004

Für die plastische Bemessung von Hochbauten im Stahlbau mit nachgiebigen Knoten stellt der Beitrag ein Bemessungsverfahren vor, das den Rotationsnachweis der Knoten einschließt. Die rechnerische Ermittlung der vorhandenen Rotationskapazität nachgiebiger Stahlknoten basiert auf experimentellen und analytischen Untersuchungen, die kurz zusammengefaßt werden. Das makromechanische Komponentenmodell bildet dabei die Grundlage der theoretischen Untersuchungen. Auf Grundlage einer umfangreichen Parameterstudie wird eine Gleichung für die vorhandene Rotationskapazität nachgiebiger Stahlknoten formuliert. Durch die Verknüpfung dieser Gleichung mit der Trägergleichung eines aus einem unverschieblichen Rahmensystem herausgelösten Trägers kann schließlich der Nachweis ausreichender Rotationskapazität nachgiebiger Stahlknoten geführt werden. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fatigue Design bei Offshore‐Windenergieanlagen
Authors: Schaumann Peter , Kleineidam Patric , Wilke Fabian
Published: October 2004

In diesem Beitrag werden Ergebnisse von Untersuchungen zum Nachweis gegen Ermüdung von Offshore‐Windenergieanlagen vorgestellt. Nach Vorstellung und Diskussion möglicher Varianten von Tragstrukturen werden verschiedene Konzepte zur Berücksichtigung der Beanspruchungen aus dem Seegang für den Nachweis gegen Ermüdung beschrieben und bewertet. Die Konzepte reichen von deterministischen Verfahren über Berechnungen im Zeitbereich zu Berechnungen im Frequenzbereich. Aufgelöste Strukturen machen zudem die Anwendung von Berechnungsansätzen erforderlich, die über das Nennspannungskonzept hinausgehen. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zur Vereinheitlichung der Stabilitätsregeln im Eurocode 3
Authors: Sedlacek Gerhard , Müller Christian
Published: October 2004

Mit der Überführung der ENV‐Fassung des Eurocode 3 in die EN‐Fassung ist es gelungen, die Stabilitätsregeln für stabförmige Bauteile (Knicken und Biegedrillknicken), für plattenförmige Bauteile (Plattenbeulen) und für Schalentragwerke (Schalenbeulen) durch die Einführung des Globalschlankheitsverfahrens zu harmonisieren. Die Abminderungsbeiwerte ρ werden über Knick‐ bzw. Beulkurven bestimmt, wobei der globale Schlankheitsgrad von dem Tragwerk und der Belastungssituation abhängt. Es wird das Vorgehen sowie die Bestimmung der Teil sicherheitsbeiwerte mit Versuchsergebnissen nach EN 1990, Anhang D – Versuchsgestützte Bemessung – vorgestellt. Das Globalschlankheitsverfahren erlaubt die Bemessung von Bauteilen und Tragwerken, die mit den bisherigen vereinfachten Verfahren nicht nachgewiesen werden konnten. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Das Hochhausensemble am Münchner Tor
Authors: Sobek Werner , Duder Michael , Winterstetter Thomas , Rehle Norbert , Hagenmayer Stephen
Published: October 2004

Die tragende Konstruktion der beiden Türme des Hochhausensembles am Münchner Tor stellt einen wichtigen Meilenstein in der Entwicklung des Hochhausbaues in Deutschland dar. Entgegen der für diese Höhen üblichen Skelettbauweise mit aussteifenden Kernen aus Stahlbeton besteht das Tragwerk der Hochhäuser des Ensembles komplett aus einer Stahlverbundkonstruktion. Über diese Konstruktion werden die vertikalen und – über Diagonalen im Sinn eines “end channel framing” – auch die horizontalen Beanspruchungen abgetragen. Lediglich die dünnen Deckenscheiben und der Kellerkasten wurden aus Stahlbeton gefertigt. Durch das gewählte Konstruktionsprinzip wurde eine bis dahin nicht gekannte Transparenz und eine außerordentliche Schlankheit der Gebäude möglich.
Höhepunkte im modernen Verbundbau – eine beispielhafte Entwicklungsgeschichte
Authors: Muess Hans , Sauerborn Norbert , Schmitt Jürgen
Published: October 2004

Die Entwicklung der Verbundbauweise im Hochbau wird aufgezeigt. Es werden die Meilensteine beschrieben, die in den letzten vierzig Jahren zu Entwicklungsschüben und damit zu ansteigender Bedeutung dieser Bauweise beitrugen: wirtschaftliche Verbundmittel, integrierter Brandschutz, fortschrittliche Anschlußtechnik und anspruchsvolle Architektur durch sichtbare Stahloberflächen.
15. DASt‐Forschungskolloquium Stahlbau
Authors: Günther Hans‐Peter , Hiller Eugen , Hüller Volker , Hothan Sascha , Grages Hauke , Kraus Oliver
Published: October 2004

Der Deutsche Ausschuß für Stahlbau (DASt) veranstaltet regelmäßig ein Kolloquium zu aktuellen Forschungsthemen aus dem Bereich des Stahlbaus. Die Veranstaltung ist vergleichbar mit einem PhD‐Symposium, im Rahmen dessen jungen Nachwuchswissenschaftlern die Möglichkeit geboten wird, ihre laufenden Forschungsaktivitäten und Ergebnisse zu präsentieren und zur Diskussion zu stellen. Das Kolloquium richtet sich hauptsächlich an Ingenieure aus der Praxis, Personen aus den Verwaltungen und andere junge Ingenieure aus der Forschung mit dem Ziel, über den gegenwärtigen Stand der Stahlbauforschung in Deutschland zu informieren. Das 15. DASt‐Forschungskolloquium fand am 1. und 2. April 2004 an der Universität Stuttgart statt. Im Rahmen des Kolloquiums war es erstmals möglich, drei der 20 Vortragenden mit Preisen für die besten Präsentationen auszuzeichnen. Dieser Beitrag schließt, neben einem allgemeinen Überblick über das 15. DASt‐Forschungskolloquium, eine kurze Zusammenfassung der drei ausgezeichneten Präsentationen ein.
Zur Entwicklung der technisch‐wissenschaftlichen Gemeinschaftsarbeit des Deutschen Stahlbau‐Verbandes – Teil I
Authors: Kurrer Karl‐Eugen
Published: October 2004

Am Beispiel des Problems der Stabknickung wird die technisch‐wissenschaftliche Gemeinschaftsarbeit des Deutschen Stahlbau‐Verbandes (DSTV) von 1904 bis 1945 dargestellt. Mit den theoretisch von Hermann Zimmermann (1845–1935) begleiteten und i. w. vom DSTV finanzierten Knickversuche des “Ausschusses für Versuche im Eisenbau” konnte in den 1920er Jahren die erweiterte Eulersche Knicktheorie glänzend bestätigt werden.

Schon früh trat mit Gottwalt Schaper (1873–1942) eine Bauingenieurpersönlichkeit in den engeren Kreis der technisch‐wissenschaftlichen Gemeinschaftsarbeit des DSTV, die diese entscheidend vorantreiben sollte: Vereinheitlichung der Stahlbauvorschriften, Einführung höherfester Stähle (St 48, St 52) und Durchsetzung des Schweißens im Stahlbau, Gründung des Deutschen Ausschusses für Stahlbau (DASt).

Eine praktische Theorie stählerner Druckstäbe, die auch den unelastischen Bereich befriedigend abdeckte, entwickelte sich in Österreich und in der Tschechoslowakei. Erarbeitet wurde sie in den 1930er Jahren von Ernst Chwalla (1901–1960), Friedrich Hartmann (1876–1945) und Karl Jez_ek (1903–1975). Mit dem “Anschluß” Österreichs und der “Zerschlagung der Resttschechei” durch das Dritte Reich sollten diese Forschungsarbeiten die Erarbeitung der DIN 4114 prägen.

Das Schweißen, die höherfesten Stähle, die Stabilitätstheorie und der Übergang von der Stab‐ zur Kontinuumsstatik sind die wichtigsten Gegenstandsbereiche der Ende der 1930er Jahre sich formierenden Stahlbauwissenschaft. Ihr Programm formulierte ein Schüler Reinhold Krohns (1852–1932) 1947 auf der Stahlbau‐Tagung des DSTV in Hannover: der ehemalige Leiter der technisch‐wissenschaftlichen Abteilung des DSTV Kurt Klöppel (1901–1985).
Bemessung und Konstruktion eines Stahl‐Verbundtragwerkes unter Berücksichtigung von seismischen Einwirkungen auf der Grundlage des New Greek
Authors: Kretz Joachim
Published: October 2004

Es wird über die Bemessung und Konstruktion eines dreigeschossigen Stahl‐Verbundtragwerks berichtet. Bei dem Bauvorhaben handelt es sich um eine Produktionshalle mit Büro‐ und Sozialtrakt. Das Gebäude besitzt eine Länge von 114 m, eine Breite von 44 m und eine Höhe von 20 m. Da das Gebäude in einer sehr erdbebengefährdeten Region in Griechenland (Erdbeben‐RisikozoneII) erstellt wurde, mußte die statisch‐konstruktive Auslegung der Konstruktion unter besonderer Berücksichtigung der griechischen Erdbebennorm, dem New Greek Aseismic Code [1], erfolgen. In den Fällen, in denen der New Greek Aseismic Code keine speziellen Anwendungsregeln vorgibt, wurden vergleichbare Regelungen aus dem europäischen Regelwerk [2] bis [4] angewandt. Die ausführende Stahlbaufirma DSD, Dillinger Stahlbau GmbH, ließ aus diesem Grunde eine Stellungnahme von Prof. Dr.‐Ing. G. Sedlacek [5] anfertigen, die die Anwendung dieser Regelungen für dieses Bauvorhaben absicherte. Die statisch‐konstruktive Bearbeitung erfolgte im Ingenieurbüro Dr. Kretz.
Studien zur Reaktivität des viergliedrigen basenstabilisierten Iminoalans [(Me3N)HAlNDipp]2 mit elementarem Iod
Authors: Bauer Tillmann , Schulz Stephan
Published: October 2004

Die Reaktion des basenstabilisierten Iminoalans [(Me3N)HAlNDipp]2 (Dipp = 2, 6‐iPr2C6H3) mit Iod erfolgt unter Substitution des hydridischen H‐Atoms am Al und gleichzeitiger Bildung von HI, welches anschließend den Lewis‐basischen Iminstickstoff protoniert. Es bildet sich ein Reaktionsgemisch aus [DippN{AlI2(NMe3)}2] (1), [DippN(H)AlI2(NMe3)] (2), [{DippN(H)}2AlI(NMe3)] (3) und DippNH2. 1‐3 wurden mittels spektroskopischer Methoden (1H‐, 13C‐, IR‐ und Massenspektrometrie) identifiziert, 1 und 2 darüber hinaus durch Einkristallröntgenstrukturanalyse.
NMR Spectroscopic Characterization of Isocyano‐ and 1, 1′‐Diisocyanoferrocene. The Molecular Structure of Isocyanoferrocene
Authors: Wrackmeyer Bernd , Maisel Heidi E. , Tok Oleg L. , Milius Wolfgang , Herberhold Max
Published: October 2004

Isocyanoferrocene (1) and 1, 1′‐diisocyanoferrocene (2) were prepared and studied by 1H, 13C, 14N and 57Fe NMR spectroscopy in order to gain a more complete data set. The NMR data of 1 (chemical shifts and coupling constants) were calculated by DFT methods [B3LYP/6‐311+G(d, p)] and compare favourably with experimental data. The molecular structure of 1 was determined by X‐ray structural analysis, and an almost undistorted ferrocene‐like geometry was found.
Two Different Structural Motifs Observed for Dimeric Dialkylaluminum and Dialkylgallium Alkynides [R2E‐C≡C‐C6H5]2
Authors: Uhl Werner , Breher Frank , Haddadpour Sima , Koch Rainer , Matar Madhat
Published: October 2004

The dialkylaluminum and dialkylgallium alkynides [R2E‐C≡C‐R′]2 (R = Me, CMe3; E = Al, Ga; R′ = Ph) containing C≡C triple bonds attached to their central aluminum or gallium atoms are easily obtained by the reactions of dialkylelement chlorides with lithium alkynides or by treatment of the corresponding alkyne R‐C≡C‐H with dialkylaluminum or dialkylgallium hydrides. The first reaction is favored by the precipitation of LiCl, the second one by the formation of elemental hydrogen. All products form dimers in which the carbanionic carbon atoms of the alkynido groups adopt bridging positions, but, interestingly, different types of molecular structures were observed depending on the steric demand of the substituents terminally attached to the aluminum or gallium atoms. The small methyl substituents gave structures in which the aluminum or gallium atoms seemed to be side‐on coordinated by the C≡C triple bonds of almost linear E‐C≡C groups. In contrast, the more bulky tert‐butyl groups forced an arrangement in which the C≡C triple bonds were perpendicular to the E‐E axis of the molecules. Different bonding modes result, which were analyzed by quantum‐chemical calculations.
Synthese, Schwingungsspektrum und Kristallstruktur des Disiloxanato‐Chloroberyllats (Ph4P)2[Be4Cl6(OSiMe2OSiMe2O)2]
Authors: Neumüller Bernhard , Dehnicke Kurt
Published: October 2004

(Ph4P)2[Be4Cl6(OSiMe2OSiMe2O)2] (1) entsteht durch Reaktion von (Ph4P)2[Be2Cl6] mit cyclo‐Hexamethyltrisiloxan in Dichlormethanlösung. Es bildet farblose, feuchtigkeitsempfindliche Kristalle, die durch ihr Schwingungsspektrum (IR, Raman) und durch eine Kristallstrukturanalyse charakterisiert wurden. 1 kristallisiert triklin in der Raumgruppe $P {\bar 1}$ mit Z = 1 und mit den Gitterkonstanten bei 193 K: a = 1050, 0(1); b = 1248, 2(1); c = 1312, 5(1) pm; α = 84, 37(1)°; β = 76, 53(1)°; γ = 70, 79(1)°; R1 = 0, 0349. 1 besteht aus (Ph4P)+‐Ionen und zentrosymmetrischen Anionen [Be4Cl6(OSiMe2OSiMe2O)2]2‐, in denen die vier Berylliumatome über gegabelte Bindungen der terminalen O‐Atome der (OSiMe2OSiMe2O)2‐‐Liganden zu Be2O2‐Vierringen verbunden sind. Die Be‐Atome dieser Vierringe sind zusätzlich über μ‐Cl‐Brücken verknüpft. 1 entsteht auch durch Reaktion von (Ph4P)2[Be2Cl6] mit Baysilon‐Dichtungsmasse.
Synthesis and Structure of [Fc(EtO)PS2]‐ Complexes
Authors: Gray Ian P. , Slawin Alexandra M. Z. , Woollins J. Derek
Published: October 2004

Reaction of Fc(S)PS2P(S)Fc with NaOEt gives the non symmetric phosphonodithioato anion [Fc(EtO)PS2]‐ which can be complexed to a range of metal ions. The group 10 metals (Ni, Pd and Pt) adopt [ML2] complexes with square planar coordination. The first known mercury phosphonodithioate complex is shown to adopt a unique dimeric [M2L4] structure. A new structural motif for lead phosphonodithioate complexes is reported consisting of [PbL2] units joined by Pb···S interactions to form distinct dimeric pairs. All new compounds have been characterized spectroscopically and four demonstrative X‐ray structures are reported.
Heterobi‐ and ‐trinuclear Complexes with an Amino(ethynyl)carbene as Bridging Ligand
Authors: Fischer Helmut , Hartbaum Cornelia , Wespel Christiane , Dede Markus
Published: October 2004

The sequential reaction of the amino(trimethylsilyl)carbene complex [(CO)5W=C(NH2)C≡CSiMe3] (1) with nBuLi and [I‐Fe(CO)2Cp] affords the C(carbene)‐N bridged heterobinuclear complex [(CO)5W=C{NHFe(CO)2Cp}C≡CSiMe3] (2). Desilylation of 1 is achieved by treatment with KF in THF/MeOH. From the reaction of the resulting complex [(CO)5W=C(NH2)C≡CH] (3) with nBuLi and [I‐Fe(CO)2Cp] two binuclear WFe compounds in a ratio of approximately 1:1 are obtained: the C(carbene)‐C≡C bridged complex 4 and the C(carbene)‐N bridged complex 5. Repetition of the deprotonation/metallation sequence yields the trinuclear WFe2 complex 6. One Fe(CO)2Cp fragment in 6 is bonded to the amino group and the other one to the terminal carbon atom of the ethynyl substituent. The analogous reaction of 3 with nBuLi and [Br‐Ni(PMe2Ph)2Mes] gives a ca. 1:1 mixture of two heterobinuclear complexes (7 and 8). Complex 7 is bridged by the C(carbene)‐C≡C and complex 8 by the C(carbene)‐N fragment. Subsequent reaction of 7 with BuLi and [Br‐Ni(PMe2Ph)2Mes] finally affords the trinuclear WNi2 complex 9 related to 6. The solid‐state structure of 2 is established by an X‐ray diffraction analysis. The spectroscopic data of the bi‐ and trinuclear complexes indicate electronic communication between the metal centers through the bridging group.
Copper(I) Coordination Polymers with Alkanedithiol and ‐dinitrile Bridging Ligands
Authors: Heller M. , Sheldrick W. S.
Published: October 2004

CuI‐based coordination polymers with 1, 2‐ethanedithiol, 3, 6‐dioxa‐1, 8‐octanedithiol and 3‐oxa‐1, 5‐pentanedinitrile as respectively μ‐S, S′ and μ‐N, N′ bridging ligands have been prepared by reaction of CuI with the appropriate alkane derivative in acetonitrile. [Cu(HSCH2CH2SH)2]I (1) contains 44 cationic nets, [(CuI)2(HSCH2CH2OCH2CH2OCH2CH2SH)] (2) neutral layers in which stairlike CuI double chains are linked by dithiol spacers. In contrast to these 2D polymers, [CuI(NCCH2CH2OCH2CH2CN)] (3) and [(CuI)4(NCCH2CH2OCH2CH2CN)2] (4) both contain infinite chains with respectively (CuI)2 rings and distorted (CuI)4 cubes as building units. Solvothermal reaction of CuI with the thiacrown ether 1, 4, 10‐trithia‐15‐crown‐5 (1, 4, 10TT15C5) in acetonitrile affords the lamellar coordination polymer [(CuI)3(1, 4, 10TT15C5)] (7) in which copper atoms of individual CuI double chains are bridged in a μ‐S1, S4 manner. The third sulphur atom S10 of the thiacrown ether coordinates a copper(I) atom from a parallel chain to generate a 2D network.
Synthesis and Structure of the First Stannadisiloxanediol: [Me2N(CH2)2]2Sn(OSit‐Bu2OH)2. A Potential Precursor for the Preparation of Multi Component Oxides
Authors: Balkenhol Dirk , Beckmann Jens , Jurkschat Klaus , Schürmann Markus
Published: October 2004

The synthesis of [Me2N(CH2)2]2Sn(OSit‐Bu2OH)2 (1) by the base‐assisted cohydrolysis of [Me2N(CH2)2]2SnCl2 and t‐Bu2SiCl2 is described. The molecular structure of 1, determined by single crystal X‐ray diffraction analysis, features a pentacoordinated tin atom owing to the intramolecular coordination of the nitrogen atom of one 3‐dimethylaminopropyl group, and reveals both intramolecular Si(Sn)O···H‐O and intermolecular N···H‐O hydrogen bonding. Compound 1 is a rare example of a metallasiloxanol and holds potential for the preparation of multi component oxide materials.
Die konjugative Verbrückung metallorganischer Reaktionszentren in Heterozweikernkomplexen [(OC)3ClRe(μ‐L)MCl(C5Me5)]+, M = Rh oder Ir ‐ Spektroskopische Konsequenzen reduktiver Aktivierung
Authors: Kaim Wolfgang , Scheiring Thomas , Weber Michael , Fiedler Jan
Published: October 2004

Heterozweikernige Komplexverbindungen [(OC)3ClRe(μ‐L)MCl(C5Me5)](PF6), M = Rh oder Ir und L = 2, 5‐Bis(1‐phenyliminoethyl)pyrazin (bpip), 3, 6‐Bis(2‐pyridyl)‐1, 2, 4, 5‐tetrazin (bptz) oder 2, 2′‐Bipyrimidin (bpym) wurden ausgehend von einkernigen Rhenium‐Komplexen (L)Re(CO)3Cl synthetisiert. Die stufenweise reduktive Aktivierung unter Chlorid‐Dissoziation wurde durch cyclische Voltammetrie und Spektroelektrochemie im Bereich der CO‐Streckschwingungen (IR), Charge‐Transfer‐Absorptionen (UV/Vis) und Elektronenspinresonanz (ESR) bei paramagnetischen Zwischenprodukten der ein‐ und zweikernigen Verbindungen untersucht. Während für Komplexe des bpip und bptz radikalische Einelektronenzwischenstufen [(OC)3ClRe(μ‐L)MCl(C5Me5)]˙ nachgewiesen wurden, reagieren die Komplexe mit bpym unter MCl‐dissoziativer Zweielektronenreduktion direkt zu den Verbindungen [(OC)3ClRe(μ‐L)M(C5Me5)].
Bei der Bildung metalloider Ga‐Cluster führen Phosphoniumbetaine zu einem Ga12‐Gerüst mit ungewöhnlichen Bindungsverhältnissen
Authors: Steiner Jochen , Stößer Gregor , Schnöckel Hansgeorg
Published: October 2004

Die Reaktion einer 3:1 Mischung aus Phosphanid und Phosphoniumylid mit einer metastabilen GaBr‐Lösung führt zu einer neutralen, metalloiden Ga12‐Clusterverbindung. Dieser hier erstmalig beobachtete metalloide Cluster mit positiv polarisierten Phosphoniumliganden und negativ polarisiertem Ga12‐Gerüst wird hinsichtlich des Ausmaßes des Ladungstransfers mit Hilfe quantenchemischer Rechnungen diskutiert. Das Potential von Phosphoniumbetainen zur Stabilisierung von metalloiden Clustern wird erörtert.
High Pressure Study of NH4Pb2Br5 Type Compounds. I Structural Parameters and Their Evolution under High Pressure
Authors: Becker Daniel , Beck Horst P.
Published: October 2004

We have investigated the nature of the interactions of ns2‐cations and the possible structure‐determining role of the ns2electron pair at ambient and high pressure in several AB2X5 (A = K, Rb, Cs, In, Tl; B = Sn, Pb, Sr; X = Cl, Br, I) compounds. Structural parameters are obtained by high pressure x‐ray diffraction as well as by quantum mechanical methods (DFT‐GGA‐calculations). The structural parameters at ambient and high pressure are discussed and compared to those of Tl5Se2I crystallising in the antitype structure. Short cation—cation distances in the NH4Pb2Br5 type structure enable direct cation—cation interactions and the existence of an ns2‐cation in the B‐position is crucial for the stability of these structures. The effect of pressure on the structural parameters of these compounds gives new insights into the interactions of lone pair cations. The pronounced decrease of the cation—cation distances with pressure points to strongly increasing bonding interactions between the lone pair cations.
Crystal and Species Engineering with Semi‐Flexible Nitrogen Containing Organic Cations: Generation of [H13O6]+Ions with the Unfavoured Unbranched Topology by Enclosing Hydrochloric Acid in a Porous Inorganic‐Organic Hybrid Material
Authors: Graf J. , Frank Walter
Published: October 2004

The reaction of rhodium(III) chloride trihydrate with 1, 4‐diazacycloheptane in concentrated hydrochloric acid results in the formation of tris(1, 4‐diazoniacycloheptane) hexaaquahydrogen(1+) bis(hexachlororhodate(III)) chloride, [C5H14N2]3[H13O6][RhCl6]2Cl (1). Dark red crystals of1are obtained by diffusion‐controlled crystallization at room temperature. Slow evaporation of the mother liquor over a period of several days yields a few tiny crystals of the bis(1, 4‐diazoniacycloheptane) hexachlororhodate(III) chloride hydrate, [C5H14N2]2[RhCl6]Cl˙1.75 H2O (2), as red thin squared plates. In the context of crystal engineering, compounds1and2are inorganic‐organic hybrid materials built up from octahedral [RhCl6]3‐, simple Cl‐and semi‐flexible heterocyclic 1, 4‐diazoniacycloheptane ions, incorporating either the [H13O6]+and further Cl‐ions or portions of simple water molecules. Both compounds crystallize in the space group typeP21/c. Compound1contains isolated [H13O6]+ions with a linear chain‐like configuration enclosed in the cavities of the inorganic‐organic framework. The presence of a strong central O···H···O hydrogen bond within the [H13O6]+ions in1is confirmed by the short O···O separation of 2.47Å and by characteristic IR absorption bands at 1626 (s), ∼ 1250 (m) and 668 (m) cm‐1. During the thermal decomposition, compound1looses at first five equivalents of water and one equivalent of hydrochloric acid in a two‐step process at 37 °C and 67 °C. This is followed by the decomposition of the 1, 4‐diazoniacycloheptane cations and the hexachlororhodate(III) anions, starting at 190 °C and proceeding intensified at 240 °C.
The Henicosaphosphide Iodides of Potassium and Rubidium, K4P21I and Rb4P21I
Authors: Hönle Wolfgang , Schmettow Walter , Peters Karl , Chang Jen‐Hui , von Schnering Hans Georg
Published: October 2004

The novel ternary polyphosphides M4P21I (M = K, Rb) have been synthesized from the elements in single crystalline form, representing further examples for the formation of mixed crystals between simple salts and binary phosphides. They form as ruby‐red platelets and dark‐red prisms, respectively, and are only slightly sensitive to moisture and oxygen. The compounds are isotypic (Ccmm (no 63); Z = 4; oP104; K4P21I: a = 12.853Å; b = 21.795Å; c = 9.748Å; 1168 hkl, R = 0.033; Rb4P21I: a = 13.281Å; b = 21.868Å; c = 9.771Å; 777 hkl, R = 0.053) and feature corrugated 2D networks formed from two different types of polymerized P7 units. The networks form large cavities filled by M+ and I‐ ions. Zigzag chains of condensed trigonal M6 prisms, centered by the I‐ anions, separate the polyphosphide nets. The mean homoatomic P‐P bond length (d = 2.216Å) corresponds to a P‐P single bond. However, the individual P‐P distances vary with position and function (2.126 ‐ 2.247Å) and these are compared with those of the isolated P21‐3 anion.
Reaktionen eines Dibismutans und von Cyclobismutanen mit Metallcarbonylen ‐ Synthesen von Komplexen mit R2Bi‐, RBi‐, Bi2‐ und Bin‐Liganden (R = Me3CCH2, Me3SiCH2)
Authors: Balázs L. , Breunig H. J. , Lork E.
Published: October 2004

Reaktionen von [Fe2(CO)9] mit [(Me3CCH2)2Bi]2 oder cyclo‐(Me3SiCH2Bi)n (n = 3 ‐ 5) führen zu den Komplexen [(R2Bi)2Fe(CO)4], [RBiFe(CO)4]2 (R = Me3CCH2, Me3SiCH2) und [Bi2Fe3(CO)9]. [Bi2{Mn(CO)2C5H4CH3}3] entsteht in einer photochemischen Reaktion aus [Mn(CO)3C5H4CH3] und cyclo‐(Me3SiCH2Bi)n.
Synthese und Struktur von Ruthenium(II)‐Komplexen mit Triazenido‐ und Pentaazadienido‐Liganden
Authors: Barboza da Silva Carlos Fernando , Schwarz Simon , Galceran Mestres Montserrat , Teijelo López Sonia , Strähle Joachim
Published: October 2004

Der Ruthenium(II)‐triazenido‐Komplex [RuCl(ClC6H4N3C6H4Cl)(p‐Cymol)] (1) entsteht bei der Umsetzung von Silber‐bis(p‐chlorphenyl)triazenid mit [RuCl2(p‐Cymol)]2 in CH2Cl2 in Form luftstabiler, gelboranger Kristalle. Er kristallisiert als 1·CH2Cl2 in der orthorhombischen Raumgruppe Pbca mit den Gitterkonstanten a = 3134, 3(3); b = 2105, 7(2); c = 769, 15(4) pm und Z = 8. Im diamagnetischen Einkernkomplex 1 koordiniert der Triazenidoligand chelatartig mit den Atomen N(1) und N(3). p‐Cymol ist über den C6‐Ring η6‐gebunden. Die Reaktion des Etherphosphan‐Komplexes [RuCl2(Ph2PCH2C4H7O2)2] mit 1, 3‐Bis(p‐tolyl)triazenid in THF ergibt den Komplex [RuCl(tolyl‐N3‐tolyl)(Ph2PCH2C4H7O2)2] (2). Von 2 werden monokline, rote Kristalle mit der Raumgruppe P21/c und a = 1521, 0(2); b = 1451, 8(2); c = 2073, 7(2) pm; β = 99, 29(1)° und Z = 4 erhalten. Im luftstabilen, diamagnetischen Komplex 2 ist das Triazenidion mit seinen Atomen N(1) und N(3) als Chelatligand gebunden. Von den beiden Etherphosphanliganden koordiniert einer chelatartig über das P‐Atom und ein O‐Atom, während der zweite Ligand einzähnig mit seinem P‐Atom bindet, so daß sich für RuII die Koordinationszahl sechs ergibt. [Ag(tolyl‐N5‐tolyl)]2 reagiert in THF mit [RuCl2(C6H6)]2 unter Bildung des an Luft stabilen, diamagnetischen Pentaazadienidokomplexes [RuCl(tolyl‐N5‐tolyl)(C6H6)] (3). 3 bildet monokline, rote Kristalle mit der Raumgruppe P21/c und a = 1462, 4(1); b = 1056, 51(8); c = 1371, 4(1) pm, β = 114, 36(1)° und Z = 4. Der Pentaazadienidoligand koordiniert mit seinen Atomen N(1) und N(3) chelatartig am zweiwertigen Ru‐Atom. Das Benzolmolekül ist über sein π‐System η6‐gebunden.
Polycyclic Phosphorus Sulfide Compounds containing Chiral Amido or Imido Substituents
Authors: Tattershall Bruce W. , Houghton Richard W. , Martin Daniel J.
Published: October 2004

Reactions of α‐P4S3I2 with (S)‐ or racemic‐RNH2 (R = CH(Me)Ph) have given solutions containing exo, exo‐ or endo, exo‐α‐P4S3(NHR)2, α‐ or β‐P4S3(μ‐NR), or P4S2(μ‐NR), as the first compounds with polycyclic phosphorus sulfide skeletons to contain chiral substituents. The expected diastereomers have been characterised by complete analysis of their 31P{1H} NMR spectra, and relative configuration has been assigned in most cases. Considerable diastereomeric differences in coupling constants and chemical shifts were found.
Complex Formation of 2, 6‐Bis‐(2′‐hydroxyphenyl)pyridine with AlIII, FeIII and CuII
Authors: Steinhauser Stefan , Heinz Uwe , Sander Jürgen , Hegetschweiler Kaspar
Published: October 2004

Complex formation of 2, 6‐bis(2′‐hydroxyphenyl)pyridine (H2Li) with Fe3+ and Cu2+ was investigated in a H2O/DMSO medium (mole fraction xDMSO = 0.2) by potentiometric and spectrophotometric methods. The pKa values of [H3Li]+ are 2.25, 10.51 and 14.0 (25 °C, 0.1 M KCl). The formation constants of [FeIII(Li)]+ and [CuII(Li)] (25 °C, 0.1 M KCl) are log β1 = 21.5 for Fe3+ and log β1 = 18.5 for Cu2+. The crystal structures of [Al(Li)2Na(EtOH)3], [Fe(Li)2Na(EtOH)3], and [Cu(Li)(py)]2 were investigated by single‐crystal X‐ray diffraction analyses. The FeIII and the AlIII compound are isotypic and crystallize in the monoclinic space group P21/n. Al‐compound (215 K): a = 12.599(3) Å, b = 16.653(3) Å, c = 17.525(4) Å, β = 100.27(3)°, Z = 4 for C40H40AlN2NaO7; Fe‐compound (293 K): a = 12.753(3) Å, b = 16.715(3) Å, c = 17.493(3) Å, β = 99.68(3)°, Z = 4 for C40H40FeN2NaO7. Both compounds contain a homoleptic, anionic bis‐complex [M(Li)2]‐ of approximate D2 symmetry. The Cu compound crystallized as an uncharged, dinuclear and centrosymmetric [Cu(Li)(py)]2 complex in the monoclinic space group P21/n with (293 K) a = 13.386(3) Å, b = 9.368(2) Å, c = 14.656(3) Å, β = 100.65(3)°, Z = 2 for C44H32Cu2N4O4. The structural properties and in particular the possible influence of the ligand geometry on the stability of the metal complexes is discussed.
1‐Aminoindan‐2‐ol, a Suitable Ligand for the Synthesis of Chiral, Intramolecularly Stabilized Compounds of Aluminum, Gallium, and Indium
Authors: Schumann Herbert , Kaufmann Jens , Dechert Sebastian
Published: October 2004

The reactions of enantiomerically pure (1R, 2S)‐(+)‐cis‐1‐aminoindan‐2‐ol, (1S, 2R)‐(‐)‐cis‐1‐aminoindan‐2‐ol, and racemic trans‐1‐aminoindan‐2‐ol with trimethylaluminum, ‐gallium, and ‐indium produce the intramolecularly stabilized, enantiomerically pure dimethylmetal‐1‐amino‐2‐indanolates (1R, 2S)‐(+)‐cis‐Me2AlO‐2‐C*HC7H6‐1‐C*HNH2 (1), (1S, 2R)‐(‐)‐cis‐Me2AlO‐2C*HC7H6‐1‐C*HNH2 (2), (1R, 2S)‐(+)‐cis‐Me2GaO‐2‐C*HC7H6‐1‐C*HNH2 (3), (1R, 2S)‐(+)‐cis‐Me2InO‐2‐C*HC7H6‐1‐C*HNH2 (4), (1S, 2R)‐(‐)‐cis‐Me2InO‐2‐C*HC7H6‐1‐C*HNH2 (5), and racemic (+/‐)‐trans‐Me2InO‐2‐C*HC7H6‐1‐C*HNH2 (6). The compounds were characterized by 1H NMR, 13C NMR, 27Al NMR and mass spectra as well as 1 and 3 to 6 by determination of their crystal and molecular structures. The dynamic dissociation/association behavior of the coordinative metal‐nitrogen bond was studied by low temperature 1H NMR spectroscopy.
Hexacoordinate Silicon(IV) Complexes with SiO6 Skeletons and Multidentate Ligands Derived from Citric Acid or Malic Acid
Authors: Tacke Reinhold , Bertermann Rüdiger , Burschka Christian , Dragota Simona
Published: October 2004

Morpholinium meso‐bis[citrato(3‐)‐O1, O3, O6]silicate (meso‐5) and racemic morpholinium bis[citrato(4‐)‐O1, O3, O6]silicate (rac‐6) were synthesized by treatment of tetramethoxysilane with citric acid and morpholine (molar ratio 1:2:2 and 1:2:4, respectively). Treatment of tetramethoxysilane with (S)‐malic acid and tri(n‐propyl)amine or tri(n‐butyl)amine (molar ratio 1:3:2) yielded tri(n‐propyl)ammonium (Λ, S, S, S)‐mer‐tris[malato(2‐)‐O1, O2]silicate ((Λ, S, S, S)‐mer‐7) and tri(n‐butyl)ammonium (Λ, S, S, S)‐mer‐tris[malato(2‐)‐O1, O2]silicate ((Λ, S, S, S)‐mer‐8). The hexacoordinate silicon compounds meso‐5·2MeOH, rac‐6·1.73MeOH, (Λ, S, S, S)‐mer‐7, and (Λ, S, S, S)‐mer‐8·2MeCN were structurally characterized in the solid state by single‐crystal X‐ray diffraction and VACP/MAS NMR spectroscopy (13C, 15N, 29Si). Upon dissolution in water at 20 °C, spontaneous hydrolysis of the λ6Si‐silicate anions was observed.
Zinkkomplexe eines neuen N, N, O‐Liganden
Authors: Trösch Alexander , Vahrenkamp Heinrich
Published: October 2004

Der dreizähnige Ligand N, N(2‐Dimethylaminoethyl)‐3, 5‐di‐tert.‐butyl‐salicylaldimin (LH) bildet sich aus dem entsprechenden Salicylaldehyd und N, N‐Dimethylethylendiamin. Mit Zinksalzen bildet er die einkernigen Halogenokomplexe [LZnCl˙CH3OH] (1) und [LZnI˙CH3OH] (2) und das vermutlich polymere Acetat [LZnOCOCH3] (3). Mit Diethylzink und Phosphorsäurediphenylester entsteht der Phosphatkomplex [LZn‐OPO(OPh)2˙CH3OH] (4). Die zwischen trigonal‐bipyramidal und quadratisch‐pyramidal liegende Koordination der Komplexe und die Art der fünf Donoren im Phosphatkomplex repräsentieren den Übergangszustand der hydrolytischen Substratspaltung in einem Zinkenzym.
Nanostructured ZrO2 and Zr‐C‐N Coatings from Chemical Vapor Deposition of Metal‐Organic Precursors
Authors: Mathur Sanjay , Altmayer Jessica , Shen Hao
Published: October 2004

Nanocrystalline zirconium carbonitride (Zr‐C‐N) and zirconium oxide (ZrO2) films were deposited by chemical vapor deposition (CVD) of zirconium‐tetrakis‐diethylamide (Zr(NEt2)4) and ‐tert‐butyloxide (Zr(OBut)4), respectively. The films were deposited on iron substrates and characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). The Zr‐C‐N films show blue, golden brown or bronze colours, with colour stability depending upon the precursor composition (pure metal amide or mixed with Et2NH). The deposition temperature showed no pronounced effect on the granular morphology of the Zr‐C‐N films. The XRD data of the films correspond to the formation of carbonitride phase whereas the XPS analyses revealed a strong surface oxidation and incorporation of oxygen in the film. The films deposited using a mixture of Zr(NEt2)4 and Et2NH showed higher N content, better adhesion and scratch resistance when compared to films obtained from the CVD of pure Zr(NEt2)4. Subject to the precursor composition and deposition temperature (550‐750 °C), the microhardness values of Zr‐C‐N films were found to be in the range 2.11‐5.65 GPa. For ZrO2 films, morphology and phase composition strongly depend on the deposition temperature. The CVD deposits obtained at 350 °C show tetragonal ZrO2 to be the only crystalline phase. Upon increasing the deposition temperature to 450 °C, a mixture of tetragonal and monoclinic modifications was formed with morphology made up of interwoven elongated grains. At higher temperatures (550 and 650 °C), pure monoclinic phase was obtained with facetted grains and developed texture.
Hydrogen Bonding in Imidazolium Nitrates [1]
Authors: Kuhn Norbert , Richter Markus , Steimann Manfred , Ströbele Markus , Sweidan Kamal
Published: October 2004

The imidazolium nitrates [ImH](NO3) (1) and [ImBr](NO3) (2) are obtained from the corresponding bromides [ImH]Br (3) and [ImBr]Br (4) and AgNO3 in excellent yields (Im = 2, 3‐dihydro‐1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐ylidene). The crystal structures of 1 and 2 consist of infinite linear chains of ions linked by H···O and Br···O contacts. In addition, stacks consisting of imidazolium and nitrate ions in the sequence ImBr/NO3/ImBr/NO3··· with parallel orientation of their plains are detected in 2. The crystal structure of 3 is also reported.
Experimental Charge Density Studies of Cyclotetrasilazane and Metal Complexes Containing the Di‐ and Tetraanion
Authors: Kocher Nikolaus , Selinka Carola , Leusser Dirk , Kost Daniel , Kalikhman Inna , Stalke Dietmar
Published: October 2004

The homologous series of parent octamethylcyclotetrasilazane (c‐NH‐SiMe2‐)4, (1), the lithium complex [(THF)2Li2(c‐N‐SiMe2‐NH‐SiMe2‐)2]2, (2), containing the cyclic dianion, and [(THF)2LiAl(c‐N‐SiMe2‐)4]2, (3), accommodating the unprecedented tetraanion [Me2SiN]4‐was synthesized to investigate the nature of the covalent Si‐N single bond in the presence of various metals. These model compounds show a wide diversity of Si‐N(H), Si‐N(M), Si‐N(H, M) and M‐N bonds and serve as bench‐mark systems to study polar bonds by high‐resolution low‐temperature X‐ray structure analysis. Experimental charge density studies reveal highly polar Si‐N bonds with remarkable ionic contribution, even in the non‐metallated starting material1. The Li‐N and Li‐O bonds have to be classified as almost purely ionic bonds with topological properties not far from those determined for NaCl.
Synthesis and Crystal Structure of Te6[MCl6] (M = Zr, Hf), Containing a Polymeric Chalcogen Cation (Te62+)n
Authors: Baumann Alexander , Beck Johannes
Published: October 2004

The reaction of tellurium, tellurium tetrachloride, and ZrCl4 or HfCl4, respectively, under the conditions of chemical vapour transport in a temperature gradient 220 → 200 °C yields black crystals of Te6[ZrCl6] and Te6[HfCl6]. While Te6[ZrCl6] is formed almost quantitatively, Te6[HfCl6] is always accompanied by neighbored phases such as Te4[HfCl6] and Te8[HfCl6]. The crystal structures of Te6[ZrCl6] (orthorhombic, Pbcm, a = 1095.4(1), b = 1085.2(1), c = 1324.5(1) pm) and Te6[HfCl6] (a = 1094.8(2), b = 1086.3(2), c = 1325.0(2) pm) are isotypic and consist of one‐dimensional polymeric (Te62+)n cations and of discrete, only slightly distorted octahedral [MCl6]2‐ anions (M = Zr, Hf). The cations are build of five membered rings which are connected via single Te atoms to a polymer ‐Te‐Te5‐Te‐Te5‐. Out of the six Te atoms of the asymmetric unit of the chain four atoms exhibit two bonds and two atoms exhibit three bonds. The connecting, threefold coordinated Te atoms of the five membered rings carry formally the positive charges. In consistence with the assumption of the presence of throughout localized bonds eH band structure calculations for Te6[ZrCl6] show semiconducting behaviour with a band gap of 1.8 eV.
Formation, Structural Characterization, and Calculated NMR Chemical Shifts of Selenium‐Nitrogen Compounds from SeCl4 and ArNHLi (Ar = supermesityl, mesityl)
Authors: Maaninen Tiina , Tuononen Heikki M. , Kosunen Katja , Oilunkaniemi Raija , Hiitola Johanna , Laitinen Risto , Chivers Tristram
Published: October 2004

Supermesityl selenium diimide [Se{N(C6H2tBu3‐2, 4, 6)}2; Se{N(mes*)}2] can be prepared in a good yield from the reaction of SeCl4 and (mes*)NHLi. The molecule adopts an unprecedented anti, anti‐conformation, as deduced by DFT calculations at PBE0/TZVP level of theory and supported by 77Se NMR spectroscopy and a crystal structure determination. An analogous reaction involving (C6H2Me3‐2, 4, 6)NHLi [(mes)NHLi] unexpectedly lead to the reduction of selenium and afforded the selenium diamide Se{NH(mes)}2 that was characterized by X‐ray crystallography and 77Se NMR spectroscopy. The Se‐N bonds of 1.847(3) and 1.852(3) Å show normal single bond lengths. The <NSeN bond angle of 109.9(1)° also indicates a tetrahedral AX2E2 bonding arrangement around selenium. Two N‐H···N hydrogen bonds link the Se{NH(mes)}2 molecule with two discrete (mes)NH2 molecules. In the solid state selenium diamide adopts the anti‐conformation, whereas in solution the presence of both syn‐ and anti‐isomers could be observed. PBE0/TZVP calculations of the shielding tensors of 28 different types of selenium‐containing molecules, for which the 77Se chemical shifts are unambiguously known, were carried out to assist the spectral assignment of Se{N(mes*)}2 and Se{NH(mes)}2.
Preparation of Nanosized Perovskite‐type Oxides via Polyol Method
Authors: Siemons M. , Weirich Th. , Mayer J. , Simon Ulrich
Published: October 2004

Several perovskite‐type nanosized oxides were prepared via polyol‐mediated synthesis. The crystallinity of the materials was analysed by X‐ray diffraction (XRD). While the “as synthesized” materials are amorphous or show very poor crystallinity, highly ordered materials could be obtained by annealing at 700 °C. Morphology of the materials was analysed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Particle size of the materials lay between 20 and 200 nm.
The Reactions of Hexafluorocyclotriphosphazene with Sodium Phenoxide
Authors: Freund Amy S. , Calichman Michael , Allen Christopher W.
Published: October 2004

The reaction of N3P3F6 (2) with NaOPh led to the phenoxyfluorocyclotriphosphazenes N3P3(OPh)nF6‐n (n = 1(3), 2(4), 3(5)). Structures were assigned using 31P decoupled 19F NMR spectroscopy. The reaction followed a non‐geminal pathway with a 50.7:49.3 cis:trans ratio for 4 and a 28.6:71.4 cis:trans ratio for 5. Comparisons to the analogous reaction of N3P3Cl6 (1) were facilitated by DFT calculations on N3P3(OPh)X5 (X = F, Cl) which show that the NBO charges on the phenyl group are invariant with respect to the identity of the phosphazene. These observations have been correlated to mechanistic models for cyclophosphazene substitution reactions.
Synthetic and Structural Studies on the Cyclic Bis(amino)stannylenes Sn[(NR)2C10H6‐1, 8] and their Reactions with SnCl2 or Si[(NCH2But)2C6H4‐1, 2] (R = SiMe3 or CH2But)
Authors: Avent Anthony G. , Drost Christian , Gehrhus Barbara , Hitchcock Peter B. , Lappert Michael F.
Published: October 2004

Treatment of {HNR}2C10H6‐1, 8 [R = SiMe3 (1), CH2But (2)] with Sn[N(SiMe3)2]2 afforded the cyclic stannylene Sn[{NR}2C10H6‐1, 8] [R = SiMe3 (3), CH2But (4)]. From 3 and SnCl2 in THF and crystallisation from toluene, the product was the crystalline tetracyclic compound $Sn(Cl)[\{\overline{N(SiMe_{3})\}_{2}C_{10}H_{6}-1, 8]Sn}Cl$ (5) as the (toluene)0.5‐solvate. Reaction of 4 with the silylene Si[(NCH2But)2C6H4‐1, 2] (6) [abbreviated as Si(NN)] in benzene and crystallisation in presence of Et2O furnished the crystalline tricyclic complex Sn[{Si(NCH2But)2C6H4‐1′, 2′}2‐{(NCH2But)2C10H6‐1, 8}] (7) as the Et2O‐solvate. Complex 5 slowly dissociated into its factors 3 and SnCl2 in toluene, but rapidly in THF. Solutions of 7 in C6D6, C7D8 or THF‐d8, studied by multinuclear, variable temperature NMR spectroscopy, revealed the presence of an equilibrium between 8 (an isomer of 7, in which the skeletal atoms of the eight‐membered ring were $\overline{SnNCCCNSiSi}$, rather than the $\overline{SnSiNCCCNSi}$ of 7) and 4 + 2 Si(NN), with 8 dominant in PhMe but not in THF; additionally 8 was shown to be fluxional and solutions of 8 in C6D6 or C7D8 decomposed to give the silane Si(NN)[(NCH2But)2C10H6‐1, 8], 6 and Sn metal. The X‐ray structures of 3, 5 and 7 are presented.
Do psychological factors increase the risk for back pain in the general population in both a cross‐sectional and prospective analysis?
Authors: Linton Steven James
Published: October 2004

This study aimed to conduct a comprehensive evaluation of background, individual and workplace psychological risk factors to investigated their relationship with spinal pain. Because there is some doubt as to whether the results of cross‐sectional findings hold in longitudinal studies, a prospective study was superimposed upon a cross‐sectional design of the effects of psychological variables on back pain and function to determine, whether similar results are obtained. Participants were workers randomly selected from the general population, where 372 had not experienced pain during the past year, and 209 had experienced considerable pain problems. A cross‐sectional comparison of these groups using multivariate statistics indicated that the most potent risk factors were psychological distress (odds ratio = 13.2) and poor function (odds ratio = 6.4). Much smaller levels of risk were found for perceived workload, gender and foreign birth. Those participants with no pain were followed for one year to determine development of a spinal pain problem. Although few participants developed a significant pain problem, the prospective analyses showed that psychological distress (odds ratio = 2.2), catastrophizing (odds ratio = 3.0), and workload (odds ratio = 2.3) produced the highest odds ratios. Taken together these results underscore the need for a multidimensional view of the development of pain disability. Moreover, individual psychological factors such as distress and catastrophizing as well as work place factors like work load were found to be highly related to the development of back pain in a sample of workers from the general population. The cross‐sectional and prospective results were similar in character and demonstrate that cross‐sectional studies may provide valuable information. Because psychological variables were relevant very early on, these factors may be important targets for pain prevention programs.
Genistein induces Gadd45 gene and G2/M cell cycle arrest in the DU145 human prostate cancer cell line
Authors: Oki Teruki , Sowa Yoshihiro , Hirose Tohru , Takagaki Nobumasa , Horinaka Mano , Nakanishi Ryoko , Yasuda Chikako , Yoshida Tatsushi , Kanazawa Motohiro , Satomi Yoshiko , Nishino Hoyoku , Miki Tsuneharu , Sakai Toshiyuki
Published: October 2004

Genistein is the most abundant isoflavone of soybeans and has been shown to cause growth arrest in various human cancer cell lines. However, the precise mechanism for this is still unclear. We report here that the growth arrest and DNA damage‐inducible gene 45 (gadd45) gene is induced by genistein via its promoter in a DU145 human prostate cancer cell line. The binding of transcription factor nuclear factor‐Y to the CCAAT site of the gadd45 promoter appears to be important for this activation by genistein.
Allele‐specific transcript isoforms in human
Authors: Nembaware Victoria , Wolfe Kenneth H. , Bettoni Fabiana , Kelso Janet , Seoighe Cathal
Published: October 2004

Estimates of the number of human genes that produce more than one transcript isoform through alternative mRNA splicing depend on the assumption that the observation of multiple transcripts from a gene can be attributed entirely to alternative splicing. It is possible, however, that a substantial proportion of cases where multiple transcripts have been observed for a gene result from differences between alleles. Many examples of genes that are spliced differently from different alleles have been reported but no systematic estimate of the proportion of alternatively spliced genes that are affected by such polymorphisms has been carried out. We find that alternative transcript isoforms are non‐randomly associated with closely linked nucleotide polymorphisms, based on an integrated analysis of the dbSNP, dbEST and ASAP databases. From the observed level of association between transcript isoforms and polymorphisms, we estimate that 21% of alternatively spliced genes are affected by polymorphisms that either completely determine which form of the transcript is observed or alter the relative abundances of some of the alternative isoforms. We provide a conservative lower bound of 6% on this estimate and point out that alternative splicing cannot be confirmed absolutely unless more than one transcript is observed from the same allele.
Adrenomedullin signals through NF‐κB in epithelial cells
Authors: Pleguezuelos Olga , Hagi-Pavli Eleni , Crowther George , Kapas Supriya
Published: October 2004

Adrenomedullin is a peptide found in a variety of cells and tissues and involved in a multitude of biological processes. Recently, adrenomedullin has been identified as a host defense peptide and as such it plays a role in the inflammatory response. The transcription factor NF‐κB is a major regulator of genes involved in the inflammatory response and the aim of this study was to determine whether NF‐κB played a role in the inflammatory process triggered by adrenomedullin. Skin epithelial cells (HaCaTs) were used as our model in vitro. Western blot analysis from adrenomedullin‐stimulated HaCaT cells revealed a rapid degradation of NF‐κB inhibitor α and β followed by the translocation of free NF‐κB to the nucleus, where it was detected by Texas Red immunostaining after incubation with adrenomedullin for 15 min. Electromobility shift assay showed that NF‐κB present in the nucleus was active, since it bound to a probe containing an NF‐κB binding site. Supershift assays indicated that p50 and p65, members of the NF‐κB family, were both part of the NF‐κB dimmers involved in adrenomedullin cell signaling. HaCaTs secreted interleukin‐6 in response to AM, which was significantly attenuated by the NF‐κB inhibitor SN‐50. Taken together, the data lend support for an immunoregulatory role for AM.
Basic fibroblast growth factor enhances PPARγ ligand‐induced adipogenesis of mesenchymal stem cells
Authors: Neubauer Markus , Fischbach Claudia , Bauer-Kreisel Petra , Lieb Esther , Hacker Michael , Tessmar Joerg , Schulz Michaela B. , Goepferich Achim , Blunk Torsten
Published: October 2004

Mesenchymal stem cells (MSCs) are capable of differentiating into a variety of lineages, including bone, cartilage, or fat, depending on the inducing stimuli and specific growth and differentiation factors. It is widely acknowledged that basic fibroblast growth factor (bFGF) modulates chondrogenic and osteogenic differentiation of MSCs, but thorough investigations of its effects on adipogenic differentiation are lacking. In this study, we demonstrate on the cellular and molecular level that supplementation of bFGF in different phases of cell culture leads to a strong enhancement of adipogenesis of MSCs, as induced by an adipogenic hormonal cocktail. In cultures receiving bFGF, mRNA expression of peroxisome proliferator‐activated receptor γ2 (PPARγ2), a key transcription factor in adipogenesis, was upregulated even prior to adipogenic induction. In order to investigate the effects of bFGF on PPARγ ligand‐induced adipogenic differentiation, the thiazolidinedione troglitazone was administered as a single adipogenic inducer. Basic FGF was demonstrated to also strongly increase adipogenesis induced by troglitazone, that is, bFGF clearly increased the responsiveness of MSCs to a PPARγ ligand.