bluuebunny/crossref_metadata_2025 huggingface dataset:
1, 1′‐Di(arylamino)ferrocenes. A New Family of Privileged [N, N] Ligands with Tunable Steric Control for Applications in Homogeneous Organometallic Catalysis and Coordination Chemistry
Authors: Siemeling U. , Auch T.‐C. , Kuhnert O. , Malaun M. , Kopacka H. , Bildstein B.
Published: July 2003

Fe[(C5H4)NHPh]2 (2a) was prepared from 1, 1′‐dibromoferrocene and N‐phenylacetamide by an Ullmann reaction and subsequent basic solvolysis of the coupling product Fe[(C5H4)N(COMe)Ph]2 (1a). This solvolysis failed in the case of the bulkier Fe[(C5H4)N(COMe)(2, 6‐Me2C6H3)]2 (1b). Fe[(C5H4)N(2, 6‐Me2C6H3)]2 (2b) and Fe[(C5H4)N(2, 4, 6‐iPr3C6H2)]2 (2c) were obtained by Hartwig‐Buchwald type cross‐coupling of 1, 1′‐diaminoferrocene with the respective aryl bromide.
Einkristall‐Synthese hochschmelzender Oxyde bei niederer Temperatur: γ‐Li4[SiO4] — ohne Fehlordnung, isotyp mit Na4[SnO4]. (Was heißt ‘Isotypie’?)
Authors: Hoppe Rudolf , Bernet Kirsten , Möller Angela
Published: July 2003

Erstmals wurde γ‐Li4[SiO4] (bei 600 °C, aus den binären Oxiden) erhalten. Die Strukturbestimmung erfolgte an farblosen Einkristallen (P 1¯, a = 751, 9 pm, b = 564, 8 pm; c = 503, 1 pm; α = 124, 15°; β = 97, 18°; γ = 100, 26°; Rw = 0, 052). γ‐Li4[SiO4] kristallisiert isotyp zu Na4[SnO4]. Vergleiche von MAPLE‐Daten belegen die Güte der Strukturbestimmung. Über die Planung weiterer Synthesen wird berichtet. Die Frage der bislang unbeachteten ‘Konnektivität’ wird angesprochen. Erstmals wird einquantitativer Vergleich der Isotypie vorgestellt.
On the Incorporation of Transition Metal Atoms into Thiostannates: Synthesis, Crystal Structures and Spectroscopic Properties of [Ni(en)3]2Sn2S6, [Ni(dap)3]2Sn2S6 · 2 H2O, [Co(tren)]2Sn2S6, and [Ni(tren)]2Sn2S6
Authors: Behrens Malte , Scherb Sandra , Näther Christian , Bensch Wolfgang
Published: July 2003

The four new thiostannates [Ni(en)3]2Sn2S6 (1) (en = ethylenediamine), [Ni(dap)3]2Sn2S6 · 2 H2O (2) (dap = 1, 2‐diaminopropane), [Co(tren)]2Sn2S6 (3) and [Ni(tren)]2Sn2S6 (4) (tren = tris(2‐aminoethyl)amine) were prepared under solvothermal conditions. In all compounds [Sn2S6]4— anions are observed as the common structural motif. This anion is composed of two SnS4 tetrahedra sharing a common edge. In compounds 1 and 2 the transition metal cations are coordinated each by three amine ligands and therefore solvent separated complex cations as well as discrete [Sn2S6]4— anions are found. In compounds 3 and 4 the coordination around the transition metal ions cannot be completed by the organic ligands and the [Sn2S6]4— anions are connected to the transition metal cations via terminal S atoms. In both compounds the [Sn2S6]4— anion acts as a bidentate ligand connecting two transition metal cations by terminal S atoms. The Co2+ cations in compound 3 are in a fivefold environment of one tetradentate tren ligand and one S atom forming discrete[Co(tren)]2Sn2S6 units. In compound 4 the Ni2+ ions are in a sixfold environment of one tetradentate tren ligand and two S atoms of two symmetry related [Sn2S6]4— anions. This connection mode leads to formation of “zig‐zag‐like” Ni—Sn2S6 chains which are directed along the crystallographic c‐axis. The spectroscopic properties of compounds 1 to 3 were investigated using Raman spectroscopy. Differences in the spectra of 1 and 2 compared to 3 are observed which are caused by the covalent bonding between the Co2+ ions and the Sn2S64— anions in 3.
Crystal Structures and Properties of the Thiostannates Eu2SnS4 and Sr2SnS4 and the Selenogermanate γ‐Sr2GeSe4
Authors: Pocha R. , Tampier M. , Hoffmann R.‐D. , Mosel B. D. , Pöttgen R. , Johrendt Dirk
Published: July 2003

Eu2SnS4, Sr2SnS4, and Sr2GeSe4 have been synthesized by heating the elements or binary precursors at 1073 K and their crystal structures were determined by single crystal methods. Eu2SnS4 crystallizes with a new structure type (Pnma, a = 11.187(2), b = 8.768(2), c = 7.538(2)Å, Z = 4), consisting of distorted [SnS4]4— tetrahedra and sevenfold coordinated Eu2+ ions. Sr2SnS4 and γ‐Sr2GeSe4 are isostructural and form a new structure type likewise (Ama2, Z = 4, Sr2SnS4: a = 9.977(1), b = 10.311(2), c = 7.243(1)Å, Sr2GeSe4: a = 10.284(2), b = 10.543(2), c = 7.411(1)Å) with more regular tetrahedral anions and strontium coordinated by seven and eight chalcogen atoms, respectively. Eu2SnS4 is a Curie‐Weiss paramagnet (7.80(2) μB/Eu; θ = 4.2(2) K) and orders antiferromagnetically at TN = 5.5(2) K with a magnetization of 6.56(5) μB/Eu at 5.5 T. The divalent nature of europium is also evident from 151Eu Mössbauer spectra which show a single signal at an isomer shift of —12.2(1) mm/s at 78 K. Full magnetic hyperfine field splitting (19.5(2) T at the europium nuclei) is observed at 4.2 K. The 119Sn spectrum shows one signal at 1.25(9) mm/s subject to quadrupole splitting of 0.76(2) mm/s. At 4.2 K a transferred hyperfine field of 3(1) T is detected at the tin site.
Synthesis and Characterization of a Series of 1, 2‐Phenylenedioxoborylcyclopentadienes
Authors: Avent Anthony G. , Davies Michael J. , Hitchcock Peter B. , Lappert Michael F.
Published: July 2003

Treatment of 1, 2‐C6H4O2BCl [B(CAT)Cl], 4‐tert‐butyl‐1, 2‐phenylenedioxo‐chloro‐borane [B(CATt)Cl] (1) or its 3, 5‐But2‐analogue [B(CATtt)Cl] (2) with the appropriate Me3Si‐cyclopentadienyllithium compound afforded in good yield C5H4(BCAT)SiMe3 (3), C5H4(BCATt)SiMe3 (4), C5H4(BCATtt)SiMe3 (5), C5H3(BCAT)(SiMe3)2 (6), C5H3(BCATt)(SiMe3)2 (7), C5H3(BCATtt)(SiMe3)2 (8), or Me2Si{μ‐C5H3(BCAT)(SiMe3)}2 (9). Compounds C5H3(SiMe3)(1, 4‐BCAT)2 (10), its B(CATt)2 (11) or B(CATtt)2 (12) analogues were prepared from C5H3(SiMe3)(SnMe3)2 and B(CAT)Cl, 1, or 2, respectively. Single crystal X‐ray diffraction on crystalline 3 and 6 established their structures. In toluene‐d8, 3, 4 and 5 exist as mixtures of up to 5 isomers. Compounds 6—12 exist as only single isomers, compound 9 shows inequivalent cyclopentadienyl rings at 223 K which exchange with each other via a sigmatropic [1, 5]‐trimethylsilyl shift exchange process at higher temperatures.
Siliciumhaltige Ringverbindungen des Galliums und Indiums — Neue Hydridogallanate
Authors: Linti Gerald , Çoban Stella , Rodig Alexander , Sandholzer Norbert
Published: July 2003

Durch Umsetzung des sonochemisch erzeugten Galliumsubiodids “GaI” mit K(THF)2Si(SiMe3)3 entsteht neben bekannten Galliumclustern das anionische 1, 3, 2, 4‐Disiladigalletan‐Derivat [{(Me3Si)3SiGaSi(SiMe3)2}2H]—K+(triglyme). Mit KOtBu reagiert GaI unter Disproportionierung zum Hydridogallanat [KHGa(OtBu)3]2 mit Käfigstruktur. Das 1, 3, 2, 4‐Disiladiindetan‐Derivat [(Me3Si)3SiInSi(SiMe3)2]2 bildet sich aus Indium(I)iodid und Li(THF)3Si(SiMe3)3. Alle Verbindungen wurden mittels Einkristall‐Röntgenstrukturanalyse untersucht.
Zwitterionic Molecules with Stanna‐closo‐dodecaborate
Authors: Ronig Benno , Pantenburg Ingo , Wesemann Lars
Published: July 2003

A series of zwitterionic molecules was synthesized by nucleophilc substitution between stanna‐closo‐dodecaborate and a series of alkyliodides like (ω‐iodo‐alkyl)trialkyl‐ammoniumiodides and 1‐(4‐iodobutyl)pyridiniumiodide. The structures in the solid state have been determined by X‐ray crystal structure analysis for Bu3N‐C3H6‐SnB11H11 (3), Pr3N‐C4H8‐SnB11H11 (6), Bu3N‐C4H8‐SnB11H11 (7) and C5H5N‐C4H8‐SnB11H11 (9).
Hexacoordinate Silicon(IV) Complexes Containing Thiocyanato‐N Ligands — Syntheses, Structural Characterization, and Computational Studies
Authors: Seiler Oliver , Bertermann Rüdiger , Buggisch Nele , Burschka Christian , Penka Martin , Tebbe David , Tacke Reinhold
Published: July 2003

The hexacoordinate silicon(IV) complexes [NEt4]2[Si(NCS)6] (2), [K(18‐crown‐6)]2[Si(NCS)6]·2CH3CN (3·2CH3CN), and cis‐[(acac)2Si(NCS)2] (cis‐4; acac = acetylacetonato‐O, O) were synthesized, starting from Si(NCS)4 (1). Compounds 1, 2, 3·2CH3CN, and cis‐4 were structurally characterized in the solid state (13C, 15N (cis‐4 only), and 29Si MAS NMR; crystal structure analyses) and in solution (1H, 13C, and 29Si NMR; cis‐4 only). The experimental investigations were complemented by computational studies (RI‐MP2 geometry optimizations of 1, [Si(NCS)6]2—, cis‐4, and trans‐4; calculations of the 29Si NMR chemical shifts using the optimized structures).
Die Dodekahydro‐closo‐Dodekaborate M2[B12H12] der schweren Alkalimetalle (M+ = K+, Rb+, NH4+, Cs+) und ihre formalen Iodid‐Addukte M3I[B12H12] (≡ MI · M2[B12H12])
Authors: Tiritiris Ioannis , Schleid Thomas
Published: July 2003

Die wasserfreien Dodekahydro‐closo‐Dodekaborate M2[B12H12] der schweren Alkalimetalle (M = K — Cs, NH4) sowie ihre formalen Iodid‐Addukte M3I[B12H12] (≡ MI · M2[B12H12]) sind durch Umsetzung einer wäßrigen Lösung von (H3O)2[B12H12] mit den entsprechenden Alkalimetallhydroxiden (MOH) oder Ammoniak (NH3) bzw. den entsprechenden Alkalimetalliodiden (MI) zugänglich. Durch Umkristallisieren aus wäßriger Lösung wurden farblose Einkristalle erhalten, die sich mittels Röntgenbeugung bei Raumtemperatur strukturell charakterisieren ließen. Die isotypen Verbindungen M2[B12H12] kristallisieren kubisch in der Raumgruppe Fm3¯ (K: a = 1062, 90(8) pm; Rb: a = 1086, 74(8) pm; NH4: a = 1087, 81(9) pm; Cs: a = 1128, 12(7) pm; Z = 4). Der Aufbau läßt sich im Sinne einer anti‐CaF2‐Struktur beschreiben, wobei die anionischen [B12H12]2—‐Cluster eine kubisch dichteste Kugelpackung bilden, in der die M+‐Kationen sämtliche Tetraederlücken besetzen. Die gemischtanionischen Verbindungen M3I[B12H12] (≡ MI · M2[B12H12]) kristallisieren allesamt isotyp in der trigonalen Raumgruppe R3¯m (K: a = 1023, 96(7), c = 1127, 83(9) pm; NH4: a = 1036, 43(7), c = 1144, 38(9) pm; Rb: a = 1040, 43(7), c = 1155, 48(9) pm; Cs: a = 1067, 80(7), c = 1197, 20(9) pm; Z = 3), wobei sich ihre Kristallstruktur auf eine trigonale Verzerrungsvariante der anti‐Perowskit‐Struktur, dem anti‐LaAlO3‐Typ, zurückführen läßt. Hierbei bilden die quasi‐ikosaedrischen [B12H12]2—‐Anionen und die M+‐Kationen gemeinsam eine kubisch dichteste Kugelpackung, in der die I—‐Anionen alle Oktaederlücken besetzen, die nur aus M+‐Kationen aufgebaut sind. Der thermische Abbau der schweren Alkalimetall‐Dodekahydro‐closo‐Dodekaborate M2[B12H12] sowie deren gemischtanionischer Iodid‐Derivate M3I[B12H12] wurde im Temperaturbereich zwischen 30 und 1200 °C mittels DTA/TG‐Methoden thermoanalytisch untersucht.
Herstellung von Eisen(II)—sulfid—Nano‐ und —Mikropartikeln in inversen Micellen
Authors: Dörr M. , Petzold H. , Kreisel G. , Völksch G. , Weigand Wolfgang
Published: July 2003

Preparation of Iron(II) Sulfide Nano‐ and Microparticles in Inverse Micells

Iron sulfide micro‐ and nanoparticles have been prepared in n‐heptane‐sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) reverse micelles at room temperature. The particles obtained are 50‐900 nm in size and form a stable dispersion for at least three months. The synthesized iron sulfide aggregates were charaterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and X‐ray diffractometry (XRD).
Polyol‐Metall‐Komplexe. 44 Phenylboronsäureester der C4‐Zuckeralkohole Erythrit und L‐Threit
Authors: Klüfers Peter , Labisch Oliver
Published: July 2003

Phenylboronsäure reagiert mit Erythrit (Eryt) und L‐Threit (L‐Thre) zu den kristallinen Estern (PhB)2(ErytH_O1, 3, O2, 4) (1a) and (PhB)2(L‐ThreH_O1, 3, O2, 4) (2a). Das Ci‐symmetrische 1a hat nach Dichtefunktionalrechnungen ähnliche Stabilität wie das entsprechende O1, 2, O3, 4‐Chelatfünfringisomer. In Lösung werden NMR‐spektroskopisch dementsprechend beide Isomere beobachtet. Der Energieunterschied zwischen dem C2‐symmetrischen 2a und dem entsprechenden Chelatfünfring‐Isomer ist dagegen größer, so dass 2a die deutlich dominierende Lösungsspezies ist.
Cationic Borabenzene Complexes as Electron Accepting Groups for Molecular Material with Nonlinear Optical Properties
Authors: Behrens U. , Meyer‐Friedrichsen T. , Heck J.
Published: July 2003

The dinuclear dipolar borabenzene complexes [(η5‐C5H5)Fe{μ‐(η5‐C5H4)C2(η6‐BC5H5)}ML]X [ML = Ru(η6‐C6H6), X = Cl (4aCl), PF6 (4aPF6), B(C6H5)4 (4aBPh4); ML = Rh(η5‐C5Me5), X = Cl (4bCl), PF6 (4bPF6); ML = Ir(η5‐C5Me5), X = Cl (4cCl), PF6 (4cPF6)] were synthesized by a nucleophilic substitution reaction of the trimethylphosphane adduct of borabenzene (1) with lithium ferrocenylacetylide, subsequent lithium‐thallium exchange and coordination of the appropriate ML unit obtained from [Ru(η6‐C6H6)Cl(μ‐Cl)]2, [M(η5‐C5Me5)Cl(μ‐Cl)]2 (M = Rh, Ir); the formed chloride salts, which are soluble in water, were transformed to the PF6 salts by adding [NH4][PF6] to the corresponding water solution. BPh4 salts can be produced, when a methanolic solution of Na[BPh4] were added to CH2Cl2‐solutions of the appropriate PF6 salt. X‐ray structure analyses of single crystals of 4aBPh4 and 4bPF6 were successful, illustrating the cation 4a+ in an ideal cis‐conformation, whereas 4b+ displays a cis‐ and trans‐conformation. Spectroscopic and cyclic voltammetry studies reveal a small but distinct donor‐acceptor interaction between the ferrocenyl donor and the cationic borabenzene complex acceptor which increases in the order 4aPF6 < 4cPF6 < 4bPF6. The nonlinear optical properties of these donor‐acceptor complexes were studied by means of hyper‐Rayleigh scattering (HRS), resulting in the determination of small values for the first hyperpolarisability ß, which increase in the same order as the donor‐acceptor interaction.
Kristallstrukturanalyse und Natriumionenleitung von wasserfreiem α‐Natriumtrifluoromethylsulfonat
Authors: Sofina Natalia , Peters Eva‐Maria , Jansen Martin
Published: July 2003

Der Einkristallstrukturanalyse bei —173 °C zufolge kristallisiert α‐NaSO3CF3 triklin in der Raumgruppe P1¯ mit den Gitterparametern a = 9, 6592(11), b = 11, 1752(12), c = 11, 2768(12) Å, α = 101, 878(2)°, β = 105, 292(2)°, γ = 110, 501(3)°, bei Raumtemperatur (22 °C) ergeben sich die Werte a = 9, 81304(18), b = 11, 3179(2), c = 11, 5910(2) Å, α = 102, 066(2)°, β = 105, 634(2)°, γ = 110, 205(2)° (Synchrotron‐Pulverdaten). In der Kristallstruktur liegen Doppelschichten aus Triflatanionen vor, in denen die unpolaren CF3‐Gruppen einander zugewandt sind. Die Natriumatome besetzen fünf verschiedene kristallographische Lagen. α‐NaSO3CF3 ist ein fester Elektrolyt, dessen spezifische Leitfähigkeit im Bereich von 1, 75·10—8 Ω—1cm—1 bei 140 °C bis 8, 78·10—6 Ω—1cm—1 bei 237 °C liegt.
Synthesen und Kristallstrukturen neuer heterobimetallischer Tantal‐Nickel‐ und Tantal‐Cobalt‐Chalkogenido‐Cluster
Authors: Pätow Richard , Isaac Ibrahim , Fenske Dieter
Published: July 2003

Durch die Reaktion von Tantalsalzen mit Nickel‐ bzw. Cobaltsalzen und silylierten Chalkogenverbindungen in Anwesentheit von Phosphanen können neue heterobimetallische kubanartige Ta—M—Chalkogen‐Cluster (M = Co, Ni) synthetisiert werden. Es werden die Verbindungen [Ta2Ni2S4Cl4(PPh3)2(MeCN)2] · MeCN (1), [Ta2Ni2Se4Cl4(PPh3)2(MeCN)2]·MeCN (2) und [TaCo3S4(NCS)3(PtBu3)3]·PtBu3·0, 5 MeCN (3) beschrieben, deren Strukturen durch Einkristall‐Röntgenstrukturanalyse aufgeklärt werden konnten.
Realstrukturen von Defektvarianten des Zinkblendetyps
Authors: Kienle Lorenz , Duppel V. , Simon A. , Deiseroth H. J.
Published: July 2003

In den Realstrukturen binärer und ternärer Defektvarianten des Zinkblendetyps treten Kristalldefekte in ungewöhnlich großer Dichte auf, die mittels hochauflösender Transmissionselektronenmikroskopie (HRTEM) und Elektronenbeugung charakterisiert werden können. Im Falle der ternären Verbindungen (CuGa3Ch5, Ch = Se, Te) beobachteten wir neben einer systematischen Verdrillingung unterschiedliche Ordnungen der Kationen in separierten Domänen der Kristalle. Die Baueinheiten von Strukturvarianten der Verbindung Ga2Te3 sind {111}‐Ebenen, in denen die Ga‐Plätze nur partiell besetzt sind. Für die Interpretation der Realstruktur werden zwei Modelle diskutiert, die auf Stapelvarianten gleicher {111}‐Ebenen oder einer Aggregation von Leerstellen in {111}‐Ebenen beruhen. Die Realstruktur kann durch die Synthesebedingungen definiert modifiziert werden. Abgeschreckte Proben sind partiell geordnet, da ebene {111}‐Defekte ein zufälliges Muster bilden. Tempern führt zu einer 10‐fachen Überstruktur längs <111>*, die in hochaufgelösten Abbildungen der <11o>‐Orientierung als geordnetes Rautenmuster aus jeder zehnten {111}‐Ebene erscheint. In Proben der Bruttozusammensetzung CaGa6Te10 finden sich als Nebenprodukt der Synthese ungewöhnliche Kristallnadeln von Ga2Te3, die zwei unterschiedlichen Varianten der Realstruktur zugeordnet werden können. Eine ist ähnlich wie die getemperte Probe geordnet, aber die Rauten in den {110}‐Abbildungen sind kleiner, da es sich vor allem um 7‐ oder 8‐fache Überstrukturen längs <111>* handelt. Die zweite Variante ist durch eine partielle Ordnung der Realstruktur charakterisiert, die sich von derjenigen bei abgeschreckten Proben unterscheidet.
Die Insertion von Chalkogenatomen in die Gallium‐Gallium‐Bindung von Acetat‐verbrückten Digallanen
Authors: Uhl Werner , Cuypers Lars , Spies Thomas , Weller Frank , Harbrecht Bernd , Conrad Matthias , Greiner Andreas , Puchner Mario , Wendorff Joachim H.
Published: July 2003

Die Dialkyldigallium(II)‐Verbindung R2Ga2(μ‐OOCCH3)2 2 [R = CH(SiMe3)2] enthält eine kurze Ga—Ga‐Einfachbindung, die durch zwei Acetatliganden überbrückt wird. Durch die chelatartige Koordination der Carboxylato‐Gruppen sind die Galliumatome mit einer Koordinationszahl von vier koordinativ gesättigt. Die Umsetzung von 2 mit Chalkogenatom‐Donoren wie Propylensulfid, Triethylphosphoniumselenid und ‐tellurid führt zur Insertion von Schwefel‐, Selen‐ oder Telluratomen in die Ga—Ga‐Bindung, wobei unter Oxidation der Galliumatome Verbindungen mit gewinkelten Ga—S—Ga‐ (3), Ga—Se—Ga‐ (4) und Ga—Te—Ga‐Einheiten (5) entstehen. In allen Fällen behalten die Carboxylato‐Gruppen ihre verbrückende Position zwischen zwei Galliumatomen bei. Die Tellurverbindung 5 zeigt einen Phasenübergang im festen Zustand, der durch Röntgenpulveraufnahmen und DSC‐Methoden eingehend untersucht wurde.
Effects of damping on mode‐coupling instability in friction induced oscillations
Authors: Hoffmann N. , Gaul L.
Published: July 2003

The mode‐coupling instability has generally been acknowledged as one of the most prominent mechanisms leading to self‐excited oscillations in sliding friction systems. The influence of structural damping on this type of instability mechanism however has not yet been fully clarified. The objective of the present work therefore is to investigate qualitative and quantitative aspects of the mode‐coupling instability in the presence of structural damping, which will be assumed as linear viscous. For the sake of simplicity a two‐degree‐of‐freedom minimal model is set up and analyzed. It is shown that under specific conditions the mode‐coupling instability may be regarded as a viscous instability in the sense that an increase in structural damping may render a stable system unstable. An explanation for this behavior is given by two lines of argument: First a description and explanation is given in terms of eigenvalue‐analysis. Due to the mathematical formality of this approach, the insight gained remains phenomenological. Second, a feedback‐loop formalism is developed that allows a more detailed understanding of the underlying mechanical processes. Based on this formalism, necessary and in sum sufficient conditions for the onset of instability can be deduced and also the role of damping can be clarified.
Small time approximations of Green's functions for one‐dimensional heat conduction problems with convective boundaries
Authors: Yen D.H.Y. , Beck J.V.
Published: July 2003

Small time approximations are obtained for Green's functions in one‐dimensional heat conduction problems with convective boundaries. The method of images similar to those for cases with Dirichlet or Neumann boundaries is used. Multiple reflections in this method generate infinite series representations for the Green's functions whose general terms involve convolution integrals with integrable singularities. We truncate the series after single and double reflections (n = 1, 2) and transform the convolution integrals to known closed‐form expressions. Numerical results are presented for n = 1, 2 and compared with exact results obtained using the classical separation of variables. It is seen that results with n = 1, 2 provide accurate approximations for dimensionless time α t / L2 up to 0.3 and complementary to those obtained by separation of variables.
Compound‐matrix Riccati method for solving boundary‐value problems
Authors: Ivansson S.
Published: July 2003

Numerically difficult boundary‐value problems for linear ODE systems can be solved with the compound‐matrix and Riccati methods. A drawback with the compound‐matrix method is that the dimensions of the ODE systems for the compound quantities can become large. Explicit quadratic relations, with relevance to quadrics in Grassmannian manifold theory, are derived for these quantities and used to reduce the system dimensions, whereby the “compound‐matrix Riccati” method appears. Compared to the traditional Riccati method, an additional forward‐sweep equation is included, which allows reconstruction of all compound‐vector elements. The well‐known singularity problems with the Riccati method are thereby removed. In particular, argument‐variation techniques for determination of eigenvalues become applicable. Seismo‐acoustic wave propagation in laterally homogeneous anisotropic media is considered as an example. The example indicates that region‐dependent mode classification, previously shown for isotropic fluid‐solid media, can be generalized to the anisotropic case. This generalization is subsequently made theoretically.
Persistence of normal hyperbolicity for partial differential equations under discretizations
Authors: Li M.‐C.
Published: July 2003

In this paper, we show that a discretization of a PDE inherits a normally hyperbolic invariant manifold from the PDE.
On the maximum and comparison principles for a steady‐state nonlinear heat conduction problem
Authors: Křížek M. , Liu L.
Published: July 2003

We examine a Dirichlet boundary value problem of elliptic type which serves as a model for a stationary heat conduction in nonlinear, inhomogeneous, and anisotropic media. We prove a comparison principle and obtain the maximum principle as a direct consequence. We also show that the standard trilinear finite elements do not preserve a discrete maximum principle.
Elastische Roboter
Authors: Bremer H.
Published: July 2003

Eine grundsätzliche Vereinfachung der Bewegungsgleichungen elastischer Roboter erhält man durch die Verwendung nichtholonomer Geschwindigkeitsvariablen. Die direkte Anwendung des Hamilton‐Prinzips bleibt jedoch auch dann extrem arbeitsaufwendig und birgt zudem mancherlei Missdeutungs‐ und damit Fehlerquellen. Eine entsprechende Auswertung führt auf die Projektionsgleichung für elastische Systeme, die wesentlich einfacher zu handhaben ist und eindeutige Ergebnisse liefert. Der Einfluss schneller Starrkörperbewegungen kann dabei auf die Wirkung einer einzigen symmetrischen Rückstellmatrix zurückgeführt werden. Die Einführung von Zwischenvariablen führt auf eine Operatordarstellung der partiellen Bewegungsdifferentialgleichungen und ihrer Randbedingungen. Für eine Näherungslösung wird ein direktes Ritz‐Verfahren vorgeschlagen. Die entsprechenden Bewegungsgleichungen sind einfach strukturiert, wenngleich natürlich hochgradig nichtlinear. Ihre Struktur lässt aber unmittelbar den Einsatz eines rekursiven Verfahrens zur numerischen Integration zu.

A fundamental simplification of the motion equations of elastic robots is obtained by the use of nonholonomic velocity variables. However, applying Hamilton's Principle still requires extreme effort and contains, additionally, sources of misinterpretations and thus possible mistakes. An adequate evaluation leads to the Projection Equation for elastic multibody systems which is much easier to handle and which delivers unique results. Thereby, the influence of fast rigid body motion dynamics is represented by one symmetric restoring matrix. Intermediate variables lead to an operator description of corresponding partial differential equations along with its boundary conditions. A direct Ritz approach is proposed for solution. The corresponding motion equations are simple in structure but, of course, highly nonlinear. Its structure, however, gives direct access to a recursive numerical integration routine.
Observations on the reproductive cycle of the black scabbardfish (Aphanopus carbo Lowe, 1839) in the NE Atlantic
Authors: Figueiredo I , Bordalo-Machado P , Reis S , Sena-Carvalho D , Blasdale T , Newton A , Gordo L.S
Published: July 2003

Black scabbardfish is a deep-water species, common in the NE Atlantic at depths between 450 and 1300 m, currently exploited by some European countries. Between May 1998 and April 2000, specimens collected at three different locations in the NE Atlantic—NW of Scotland, Sesimbra (mainland Portugal) and Funchal (Madeira)—were analysed. The evolution of maturity of both sexes throughout the year was studied based on the macroscopic and microscopic analysis of the gonads. Specimens with the largest total length were found in Funchal, whereas the smallest size was recorded in the NW of Scotland. Neither spawners nor post-spawners were ever observed in NW of Scotland and Sesimbra. In Sesimbra, only a few individuals attained pre-spawning stage and most of the early developing females exhibited atresia in their ovaries. In Funchal, all the maturity stages were found; spawners occurred from September to December (females) and from August to December (males). Length of first maturity for females was estimated to be around 1000 mm. Two groups of spawners with different sizes were observed during the spawning period off Madeira.
Konstruktion eines Komplexen Konzentrationstests
Authors: Westhoff Karl , Graubner Jörg
Published: July 2003

Zusammenfassung. Diese Studie befasst sich mit der Konstruktion eines Komplexen Konzentrationstests. Die verwendeten Aufgabenarten waren (a) einfache Rechenaufgaben, (b) Zeichen durchstreichen und (c) die Buchstabenfolge von Wörtern umgekehrt hinschreiben. Fünf Subtests von jeder Aufgabenart dauerten jeweils zwei Minuten. - N = 85 SchülerInnen von drei Klassen der achten Jahrgangsstufe eines naturwissenschaftlichen Spezialgymnasiums nahmen zwei Mal, im Abstand von zwei bis fünf Wochen, an der Untersuchung teil. Weitere Tests waren die Standard Progressiven Matrizen von Raven sowie zwei bekannte Konzentrationstests (Test d2: Buchstaben durchstreichen, KLT: einfache Rechenaufgaben). Die Noten der SchülerInnen in verschiedenen Fächern wurden von diesen durch Selbstauskunft erhoben. - Die Anzahl der richtig bearbeiteten Aufgaben (GZ-F) und der prozentuale Fehleranteil (F%) erwiesen sich als reliable und valide Maße für Konzentration. Die konvergente und diskriminante Validität erwies sich als hinreichend. Der Zeichen-Durchstreichtest sollte verbessert werden.
Das “Parent-Child Relationship Inventory“ als deutschsprachiges Eltern-Diagnostikum
Authors: Steinmetz Martina , Hommers Wilfried
Published: July 2003

Zusammenfassung. Geprüft wurde, ob das amerikanische Parent-Child Relationship Inventory (PCRI) mit sieben Inhaltsskalen zur Erfassung der Eltern-Kind-Beziehung aus Elternsicht für die Beurteilung deutscher Eltern im Kontext von Erziehungspsychologie oder familienrechtlicher Begutachtung geeignet ist. In Testanalysen anhand einer deutschen Stichprobe (n = 334 Elternpaare) fielen die Mittelwerte der Inhaltsskalen anders und interne Konsistenzen schlechter aus als in der amerikanischen Eichstichprobe. Faktorenanalysen sprachen für eine vierfaktorielle Struktur des PCRI sowohl für Väter als auch für Mütter. Hinweise auf konvergente/diskriminante Validität der aufgrund dieser Ergebnisse neu gebildeten Skalen ergaben sich aufgrund von Korrelationen mit zwei Erziehungsverhaltens-Skalen. Aber eine Instruktion, den PCRI mit der Vorstellung, man werde wegen eines Antrags auf Alleinige Sorge begutachtet, zu bearbeiten, führte zu einer signifikanten Veränderung der Skalenmittelwerte in Richtung auf die Darstellung einer “idealen“ Eltern-Kind-Beziehung. Unter dieser Bedingung verringerten sich auch konkurrente korrelative Beziehungen zum Erziehungsverhalten. Die Einsatzmöglichkeiten der deutschen Version des PCRI werden auf der Basis dieser Ergebnisse diskutiert.
Der SF-12 - Das Problem der Missing Data
Authors: Morfeld Matthias , Dietsche Stefan , Bürger Wolfgang , Koch Uwe
Published: July 2003

Zusammenfassung. Der SF-12 stellt die Kurzform der Short Form 36 Health Survey dar. Ein wenig beachteter Nachteil im Algorithmus zur Bildung der Skalenindizes liegt darin, dass die Bildung der Skalenwerte nur dann empfohlen wird, wenn alle Items von einer Person beantwortet wurden. Ist dies nicht der Fall, ist die entsprechende Person nicht mit Werten des SF-12 repräsentiert (Missing Case). Im Rahmen einer Studie zum Wirksamkeitsvergleich in der orthopädischen medizinischen Rehabilitation konnten zu Beginn (t1) und Ende (t2) der Rehabilitationsmaßnahme insgesamt 1176 Patienten erreicht werden. Trotz weitestgehend vollständiger Datensätze kam es zu t1 zu 29% fehlender Fälle im SF-12. Die Verteilungsanalyse dieser Missing Data wies v.a. darauf hin, dass es Personen höheren Alters und geringerer Schulbildung sind, die die Items des SF-12 nicht beantworteten. Insbesondere bei den aufwändig formulierten Items gibt es einen hohen Anteil fehlender Werte. Eine Überarbeitung des Instruments mit dem Ziel der Vereinfachung der Fragestellungen scheint damit erforderlich.
Ärgerbezogene Reaktionen und Ziele: Entwicklung eines neuen Fragebogens
Authors: Weber Hannelore , Titzmann Peter
Published: July 2003

Zusammenfassung. Ein neues Verfahren zur Erfassung ärgerbezogenen Verhaltens wurde entwickelt, der Fragebogen zu ärgerbezogenen Reaktionen und Zielen (AERZ). Die Konstruktion verfolgte die Ziele, ein multidimensionales, aber ökonomisches Instrument zu entwickeln, mit dem effektive und ineffektive ärgerbezogene Reaktionen sowie ärgerbezogene Verhaltensziele erfasst werden. Ausgehend von kognitiven Theorien und Befunden zum Ärger wurden insgesamt 6 Reaktions- und 6 Ziel-Skalen mit je vier Items theoretisch abgeleitet und in zwei Studien mit N = 159 und N = 174 Teilnehmer/innen überprüft. Die interne Konsistenz schwankt zwischen .68 und .90 für die Reaktions- und Ziel-Skalen; die Retest-Koeffizienten variieren zwischen .62 und .82 für die Reaktions-Skalen und zwischen .46 und .66 für die Ziel-Skalen. In exploratorischen Faktorenanalysen finden sich die postulierten sechs Faktoren für die Reaktionen und für die Ziele auf der Grundlage des Kaiser-Guttman Kriteriums sehr gut wieder. Die für Reaktionen und Ziele jeweils theoretisch postulierte 6-Faktoren Struktur wird durch konfirmatorische Faktorenanalysen für die Reaktions-Skalen, nicht aber für die Ziel-Skalen bestätigt. Zusammenhänge zwischen den Reaktions-Skalen und dem STAXI, der PANAS und der TMMS geben deutliche Hinweise auf die Validität des neuen Fragebogens.
Polar observations of transverse magnetic pulsations initiated at substorm onset in the high‐latitude plasma sheet
Authors: Toivanen P. K. , Baker D. N. , Peterson W. K. , Singer H. J. , Watermann J. , Wygant J. R. , Russell C. T. , Kletzing C. A.
Published: July 2003

This paper presents simultaneous observations of 6‐mHz magnetic pulsations in the nightside high‐latitude plasma sheet, inner plasma sheet at the geosynchronous distance, and auroral region on the ground in association with substorm onset. We study an isolated substorm (AE ∼ 300 nT) onset on 19 October 1999 at ∼0145 UT. The Polar spacecraft was located in the plasma sheet near the plasma sheet boundary and was magnetically conjugate with the Greenland west coast magnetometer chain. Polar measured large‐amplitude transverse magnetic (10 nT; toroidal) and electric (20 mV m−1) field oscillations (∼6 mHz) during the early development of the negative bay (300 nT) in Greenland. On the ground, pulsations (50 nT) with the same frequency were superimposed on the negative bay. The geostationary GOES 8 spacecraft was located 2 hours west of Greenland. It observed compressional magnetic field oscillations (1 nT and ∼6 mHz). At Polar the pulsations were initiated ∼3 min before the first outward propagating substorm signature, an abrupt enhancement of the plasma sheet electron fluxes. Such a rich data set allows us to study in detail the spatial origin of the pulsations, their timing with respect to the negative bay onset, and their role in initiation of the substorm current wedge. It is concluded that the pulsations were initiated between the plasma sheet boundary and the tailward expanding region of the enhanced plasma sheet electron fluxes. The pulsations were then later observed on the ground and at GOES 8. It can also be argued that the pulsations were an integral part of the formation of the substorm current wedge. Finally, we suggest that the pulsations were generated by periodic variations in the rate of the current diversion from the braking region of the earthward flows generated by reconnection at the near‐Earth neutral line.
Anomalous stress diffusion in earthquake triggering: Correlation length, time dependence, and directionality
Authors: Huc Mireille , Main Ian G.
Published: July 2003

It has been recently suggested that moderate and large earthquakes can be triggered by similarly sized events at very long range. Here we study the main characteristics of earthquake triggering by determining its correlation length, time dependence, and directionality. The problem is examined at a global level, by using the Harvard centroid moment tensor catalogue. Our results show that the correlation lengths depend only weakly on the magnitude thresholds involved. No significant systematic triggering is observed for distances greater than the lithospheric thickness (100–150 km), and the correlation length magnitude is similar to the seismogenic thickness (10–20 km). The mean triggering distance and correlation length both increase with time very slowly compared with what would be expected from a normal diffusion process. This is consistent with a clock advance on the failure time based on the constitutive rules for subcritical crack growth following a transient change in the loading stress. The power law scaling disappears after a few months. A functional form for the probability of triggering as a function of time and distance is proposed on the basis of the properties of near critical point systems. The model fits the data well and could be used to calculate conditional probabilities for time‐dependent seismic hazard due to earthquake triggering. An apparent directionality effect that was observed in the data set can be attributed to an artefact of poor depth determination. These results do not preclude individual long‐range triggering with a potential directionality effect, but they do rule out a statistical correlation at distances much greater than the thickness of the lithosphere.
Spectral estimates of bed shear stress using suspended‐sediment concentrations in a wave‐current boundary layer
Authors: Lee Guan‐Hong , Dade W. Brian , Friedrichs Carl T. , Vincent Chris E.
Published: July 2003

High‐resolution time series of suspended‐sediment profiles have been obtained using an acoustic backscatter system at an inner shelf site (North Carolina) where flows are dominated by wind‐driven currents and waves. We analyzed the spatial and temporal structure of near‐bed turbulence in particle‐transporting flows and scalar‐like fluctuations of suspended‐sediment concentrations. An important element of our analysis is a new inertial dissipation method for passive tracers to estimate the shear stress acting on the seabed, using the spectral properties of suspended sediment concentrations observed by acoustic backscatter sensors. In flows that provide adequate separation of the scales of turbulence production and dissipation, a sufficiently thick constant stress wall layer, and significant sediment suspension, frequency (or associated wave number) spectra of near‐bed sediment concentration exhibit a −5/3 slope in the inertial subrange that spans frequencies of order 1 Hz. This observation suggests that the suspended sediment is effectively a passive tracer of turbulent fluid motions. Inversion of the relevant, Kolmogorov scaling equations yields estimates of the shear velocity that agree reasonably well with other, independent and widely used measures. High‐ and low‐frequency limits on application of the inertial dissipation method to sediment concentration are related to the inertial response time of sediment particles and the sediment settling timescale. We propose that, in future applications, the inertial dissipation method for passive tracers can be used to estimate either the shear velocity, effective settling velocity of suspended sediment (or equivalent particle size) or dynamic bed roughness if two of these three quantities are independently known.
Pancake ice formation in the Weddell Sea
Authors: Doble Martin J. , Coon Max D. , Wadhams Peter
Published: July 2003

The ice formation resulting from two low temperature events at the Weddell Sea ice edge during April 2000 is presented. Pancake and frazil ice were sampled at seven stations at varying distances from the ice edge. The ice cover was further characterized from above, using helicopter aerial photography, and from below, using a remotely operated vehicle. Previously undescribed two‐layer pancake types were observed and classified. A novel pancake growth mechanism is introduced to account for these, involving the washing of frazil ice over the pancake top surface and its subsequent freezing. The process was directly observed in ice tank experiments. Layer thicknesses seen in the field were compared to the ice growth that would occur both under calm conditions and from free‐surface frazil ice growth. Classical, bottom accretion, pancake growth was found to proceed at a rate similar to that of thin congelation ice. Top‐layer growth was more rapid, at approximately double the congelation rate. Overall ice volume production was similar to congelation ice for the thin pancakes considered (∼20 cm), though subsequent thickening was expected to be faster as the rapid top‐layer process continued and the equivalent congelation growth slowed. It is suggested that parameterization of this new process is important for models that aim to simulate the rapid advance and thickening of wave‐influenced ice covers.
Application of a new wind gust parameterization: Multiscale case studies performed with the Canadian regional climate model
Authors: Goyette Stéphane , Brasseur Olivier , Beniston Martin
Published: July 2003

The implementation of a physically based parameterization scheme for computation of wind gusts in a numerical regional climate model (RCM) is described in this paper. The method is based on an innovative approach proposed by Brasseur [2001] that assumes that gusts occurring at the surface result from the deflection of air parcels flowing higher in the boundary layer. Our parameterization scheme is developed so as to use quantities available at each model time step: consequently, the gusts are also computed for each of these time steps. To illustrate the performances of this novel method, gusts simulated for two severe midlatitude windstorms with the Canadian RCM at various resolutions are compared with observed gust speeds. The study is carried out concurrently for the complex terrain of Switzerland and for the smoother topography of Belgium. A preliminary analysis indicates that this parameterization performs equally well over flat and over mountainous regions; it also responds properly in the strengthening as well as the weakening phases of wind storms. The storm‐dependent results rely on the model configuration associated with the downscaling procedure, as well as on the accuracy of the simulated flow fields. The model response is dependent on the resolved topography distribution and height and on the types of lower boundary conditions that affect the stability of the boundary layer. The simulated gusts are generally more realistic at higher resolution over the complex topography of Switzerland but are less sensitive to resolution over the flat terrain as in Belgium. On the basis of these two storms, this study also shows that simple scaling coefficients relating gust speeds and resolution are not an appropriate method for addressing such issues.
Concentration and stable carbon isotopic composition of ethane and benzene using a global three‐dimensional isotope inclusive chemical tracer model
Authors: Thompson Alexandra , Rudolph Jochen , Rohrer Franz , Stein Olaf
Published: July 2003

A three‐dimensional global chemical tracer model of the atmosphere has been adapted to include the stable carbon isotopic composition and isotopic fractionation of ethane and benzene. For computational efficiency the chemistry was based on a prescribed OH‐radical concentration field, and therefore the feedback of ethane and benzene chemistry on the atmospheric OH‐radical concentrations was not considered. The Emission Database for Global Atmospheric Research (EDGAR) V2.0 emission database used needed to be scaled by a factor of 2.22 in order to have good agreement between observed and modeled concentrations. Modeled isotopic compositions were consistent with the few published observations. The global distribution of modeled stable carbon isotope ratios and the derived mean photochemical ages of ethane and benzene are presented. The model predicts distinct regimes of photochemical aging and air mass mixing for polar regions.
Glacial South Atlantic surface temperatures interpolated with a semi‐inverse ocean model
Authors: Grieger Björn , Niebler Hans‐Stefan
Published: July 2003

To drive an atmospheric general circulation model, sea surface temperatures (SSTs) are needed as lower boundary condition. These are well known for the modern ocean, but for other time slices the database is very sparse, and often complete global SST fields are not available. To circumvent this problem, the “SIMPLE ocean” model has been developed, which estimates surface currents in a diagnostic manner from surface winds. Horizontal heat transports by advection and diffusion and surface heat fluxes are used to calculated SSTs. The unknown transports from the deep ocean are inversely estimated from sparse SST data. The model can be understood as a method to estimate a global SST field from a sparse data set, where it takes into account the wind driven surface circulation. The SIMPLE model is applied to a set of Last Glacial Maximum SSTs reconstructed from a new South Atlantic core data set. The resultant completed SST field exhibits more structure than the CLIMAP reconstruction with larger glacial cooling in the central equatorial Atlantic and off the shore of Angola/Namibia and less cooling in the central South Atlantic.
Moving target detection in over‐the‐horizon radar using adaptive chirplet transform
Authors: Wang Genyuan , Xia Xiang‐Gen , Root Benjamin T. , Chen Victor C.
Published: July 2003

In over‐the‐horizon radar (OTHR) moving target detection, the signal to clutter ratio (SCR) is low for slow targets near the clutter, such as ships. One method to detect a moving target is to first reject the clutter and improve the SCR before the detection, such as the adaptive Fourier transform developed by Root [1998a, 1998b, 1998c] when a target moves uniformly. When a target does not move uniformly, the Fourier‐based techniques for the target detection including superresolution techniques may not work well. In this paper, we propose an adaptive chirplet transform technique in the Doppler processing in OTHR as an alternative of the Fourier transform technique when a target moves nonuniformly.
A new geodynamic interpretation for the South Portuguese Zone (SW Iberia) and the Iberian Pyrite Belt genesis
Authors: Onézime Jérôme , Charvet Jacques , Faure Michel , Bourdier Jean‐Louis , Chauvet Alain
Published: July 2003

The South Portuguese Zone (SPZ) constitutes the southernmost segment of the Variscan Iberian Massif. It is bounded to the north by the Beja‐Acebuches Ophiolitic Complex and related accretionary wedge. To the south lie the Iberian Pyrite Belt (IPB) and flysch deposits forming the southern extent of the zone. Structural analysis within the Spanish side of the SPZ supports continuous south propagating deformation, evolving from early synmetamorphic thrusting in the internal zone to thin‐skinned tectonics in the southern external domain. The accretion of the SPZ to the Ossa Morena Zone is also witnessed by the presence of various mélanges, observed throughout the investigated area. Part of the mélanges observed in the IPB are related to the volcanics and mineralizations setting. A key point to understand the IPB mineralizations genesis is to constrain the volcanogenic model. One underestimated feature is the large amount of submarine calc‐alkaline ignimbritic facies, implying the presence of caldera structures within the province. Such correlation between caldera environment and ore deposits strongly suggests that the IPB developed in a continental arc. Our geodynamic model proposes an early north directed subduction associated with the obduction of the oceanic crust toward the south. Southward, this episode is immediately followed by the development of the accretionary prism, while farther south, a second subduction zone responsible for the arc setting of the IPB initiates. Subsequent Visean continental collision is associated with the deposit of the south propagating flysch and the present geometry of the SPZ.
Multivariate rainfall disaggregation at a fine timescale
Authors: Koutsoyiannis Demetris , Onof Christian , Wheater Howard S.
Published: July 2003

A methodology for spatial‐temporal disaggregation of rainfall is proposed. The methodology involves the combination of several univariate and multivariate rainfall models operating at different timescales, in a disaggregation framework that can appropriately modify outputs of finer timescale models so as to become consistent with given coarser timescale series. Potential hydrologic applications include enhancement of historical data series and generation of simulated data series. Specifically, the methodology can be applied to derive spatially consistent hourly rainfall series in rain gages where only daily data are available. In addition, in a simulation framework the methodology provides a way to take simulations of multivariate daily rainfall (incorporating spatial and temporal nonstationarity) and generate multivariate fields at fine temporal resolution. The methodology is tested via a case study dealing with the disaggregation of daily historical data of five rain gages into hourly series. Comparisons show that the methodology results in good preservation of important properties of the hourly rainfall process such as marginal moments, temporal and spatial correlations, and proportions and lengths of dry intervals as well as a good reproduction of the actual hyetographs.
Statistical analysis of daily seismic event rate as a precursor to volcanic eruptions
Authors: Chastin Sebastien F. M. , Main Ian G.
Published: July 2003

We analyse time series of daily seismic event rate for the Kilauea, Hawaii, volcano between 1959 and 2000. Individual eruptions are not always preceded by an increase in event rate, and many increases in event rate do not lead to eruption. However, a mean field accelerating behaviour does emerge 10–15 days before eruption in data stacked in phase with the eruption time. In phase space the pre‐eruptive dynamics is well defined by Voight's [1988] equation, but so is that of the seismicity in the period between eruptions. We conclude that the underlying dynamics of the 'background' seismicity is similar to that of magma eruption. We use Bayesian methods to compare different time‐to‐failure models that have been suggested for precursors. Only a short‐term forecast can be achieved, using a linear fit to inverse rate.