bluuebunny/crossref_metadata_2025 huggingface dataset:
Loss of regularity for the solutions to hyperbolic equations with non‐regular coefficients—an application to Kirchhoff equation
Authors: Hirosawa Fumihiko
Published: May 2003

We consider the Cauchy problem for second‐order strictly hyperbolic equations with time‐depending non‐regular coefficients. There is a possibility that singular coefficients make a regularity loss for the solution. The main purpose of this paper is to derive an optimal singularity for the coefficient that the Cauchy problem is C∞ well‐posed. Moreover, we will apply such a result to the estimate of the existence time of the solution for Kirchhoff equation. Copyright © 2003 John Wiley & Sons, Ltd.
3D FE implementation of an incompressible quadriphasic mixture model
Authors: van Loon R. , Huyghe J. M. , Wijlaars M. W. , Baaijens F. P. T.
Published: May 2003

A quadriphasic mixture model, intended to apply to biological tissues, consists of a deforming solid saturated with a fluid, cations and anions. Governing equations of the model are briefly given. The coupled set of differential equations are solved in a finite element method using a weighted residual approach (updated Lagrange). A Newton–Raphson iteration scheme is applied for linearization of the non‐linear set of equations. Interpolation functions are chosen equal to the weighting functions (Galerkin) in discretization. The FE model is then validated for small deformations using the analytical solutions for 1D confined consolidation and swelling. The 3D effects are shown in a swelling cylindrical hydrogel sample. Copyright © 2003 John Wiley & Sons, Ltd.
Elastoplastic stability analysis of shells using the physically stabilized finite element SHB8PS
Authors: Legay Antoine , Combescure Alain
Published: May 2003

In this paper, we present the formulation of the SHB8PS element, its implementation into the incremental, non‐linear and implicit calculation code Stanlax‐INCA and examples of applications which demonstrate its efficiency. This element is an 8‐node, three‐dimensional cube with a preferential direction called the thickness. Therefore, it can be used to represent thin structures while, at the same time, correctly taking into account phenomena throughout the thickness thanks to the use of a numerical integration with five Gauss points in that direction. This element is subintegrated and thus requires a stabilization mechanism in order to control the hourglass modes. The stabilization technique used is based on the works by Belytschko and Bindeman, which apply an ‘assumed strain method’. The main advantage of this element is the adaptivity of its stabilization term, which is made variable with the elastoplastic evolution throughout the thickness. Copyright © 2003 John Wiley & Sons, Ltd.
Implicit time integration for the material point method: Quantitative and algorithmic comparisons with the finite element method
Authors: Guilkey J. E. , Weiss J. A.
Published: May 2003

An implicit integration strategy was developed and implemented for use with the material point method (MPM). An incremental‐iterative solution strategy was developed around Newton's method to solve the equations of motion with Newmark integration to update the kinematic variables. Test problems directly compared the implicit MPM solutions with those obtained using an explicit MPM code and implicit finite element (FE) code. Results demonstrated very good agreement with FE predictions and also illustrated several advantages in comparison to calculations using the explicit MPM code. In particular, the accuracy of the implicit solution was superior to the explicit MPM when compared to validated FE solutions, and by definition the implicit time integration is unconditionally stable. Similarities between the assembly of the implicit MPM equations and those of the FE method were identified and should allow further algorithmic improvement. Copyright © 2003 John Wiley & Sons, Ltd.
Elimination of light‐induced degradation with gallium‐doped multicrystalline silicon wafers
Authors: Dhamrin M. , Hashigami H. , Saitoh T.
Published: May 2003

Lifetime stability of gallium‐doped multicrystalline silicon wafers has been evaluated under illumination. Quality and stability of the Ga‐doped multicrystalline silicon wafers were intensively studied by means of quasi‐steady‐state photocondcutance lifetime measurement. Results show that as‐grown Ga‐doped multicrystalline silicon wafers have high lifetimes, and no significant degradation was observed under illumination. The Ga‐doped multicrystalline silicon wafers are a promising material for future photovoltaics. Copyright © 2003 John Wiley & Sons, Ltd.
The current–voltage characteristic of the ideal two‐terminal tandem solar cell
Authors: De Vos Alexis
Published: May 2003

An ideal tandem solar cell, with an infinite number of diodes, has the same limit efficiency whether or not the diodes are connected electrically in series. In case of a series connection, the device has a single current–voltage characteristic. The latter can easily be deduced, and its efficiency therefore can easily be calculated. Copyright © 2003 John Wiley & Sons, Ltd.
Self‐efficacy, goal orientation, and fear of failure as predictors of school engagement in high school students
Authors: Caraway Kirsten , Tucker Carolyn M. , Reinke Wendy M. , Hall Charles
Published: May 2003

Lack of school engagement among adolescents in this country remains a problem that can have very serious consequences including increased risk for school dropout, substance use, teenage pregnancy, and criminal activity. Clearly, identification of psychological variables (self‐variables) of individuals that facilitate or hinder adolescents' levels of school engagement would contribute greatly to the understanding of how to increase adolescents' psychological well‐being and their achievement motivation and associated school engagement. The present study examined the degree of association of three specific self‐variables (self‐efficacy, goal orientation, and fear of failure) with school engagement for high school students. The results and implications for intervention and future research are addressed. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 417–427, 2003.
Differences between WISC‐R and WISC‐III performance scale among children with ADHD
Authors: Mahone E. Mark , Miller Teresa L. , Koth Christine W. , Mostofsky Stewart H. , Goldberg Melissa C. , Denckla Martha B.
Published: May 2003

Reviews involving the Wechsler Scales for children suggest that Full Scale IQ scores on the Wechsler Intelligence Scale for Children, Third Edition, average 5 to 6 points lower than scores on the second edition of the scale [WISC‐R, Wechsler, D. (1974). Zimmerman & Woo‐Sam, 1997], with the differences distributed disproportionately over subtests, i.e., with larger discrepancies found within the Performance Scale (Wechsler, 1991). Changes on the revised subtests of the WISC‐III Performance Scale may place children with ADHD at a disadvantage compared to their performance on analogous WISC‐R subtests. We examined IQ test performance in 122 unmedicated children with ADHD (61 given the WISC‐R, 61 given the WISC‐III), and 46 children from a healthy, comparison group (23 given the WISC‐R, 23 given the WISC‐III). The ADHD and comparison group samples were matched for sex and for Verbal IQ between WISC‐R and WISC‐III. Children with ADHD had significantly lower Performance IQ on WISC‐III compared to the WISC‐R, with the Picture Arrangement subtest showing the most significant difference. In contrast, there were no significant differences between the WISC‐R and WISC‐III cohorts on Performance IQ or any Performance subtests among the comparison group. These findings highlight the importance of examining the comparability of ability test revisions among clinical and non‐clinical populations, and will be especially salient when the WISC‐III is revised. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 331–340, 2003.
The perceptions, policy, and practice of educating twins: A review
Authors: Beauchamp Heather M. , Brooks Lawrence J.
Published: May 2003

Twin births are increasing at a rapid rate, yet many educational personnel throughout the world are unaware of the needs of twins in school. Stereotypical views of twins as pathologically close or excessively dependent pervade educational policies and practices, despite the fact that twins do not differ from singletons on rates of psychological disturbance. Research shows that many schools implement strict policies for classroom placement of twins, yet the effects of such policies on twins' development and educational attainment are currently unknown. Recommendations for school personnel and future directions for this formative area are discussed. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 429–438, 2003.
Particle Imaging Using a Transmission Wide‐Field Phase Confocal Microscope
Authors: Astrakharchik‐Farrimond Eugene , Shekunov Boris Y. , Sawyer Nicolas B. E. , Morgan Stephen P. , Somekh Michael G. , See Chung W.
Published: May 2003

A phase‐sensitive wide field transmission microscope, combining the advantages of both interferometric and confocal techniques, has been developed and applied to analysis of particulates, both in dry powder form and in suspensions. The microscope has also been used in detecting defects in crystals. Confocal operation is achieved by superimposing speckle illumination of a reference beam in a Mach‐Zehnder interferometer with a matched speckle pattern of the object beam. It is shown that the phase measurement enables particle size to be determined even when the particle is smaller than the focal spot size. The data acquisition time is below 1ms, making the system suitable for dynamic process measurement. The experimental results are in good agreement with modelled results giving rise to the possibility of simultaneous determination of both the size and refractive index of small particles.
Determination of Soot Particle Size in a Premixed Flame: a Static and Dynamic Light Scattering Study
Authors: Kroner Gert , Fuchs Heribert , Tatschl Reinhard , Glatter Otto
Published: May 2003

In this contribution we report upon our static and dynamic light scattering experiments to characterize soot particles in flames. We studied sooting laminar premixed flame with acetylene as fuel mixed with air as oxidizer. The air equivalence ratio of the combustion was larger than one. We used a Kaskan type burner with circular geometry and a stabilizing flow of nitrogen around the flame. We focused on the determination of the size of the soot particles in the center of the flame as a function of height above burner. In addition we investigated the influence of the mixing ratio of the gases on the size of the particles. Our results show that static light scattering is better suited than dynamic light scattering for a fast and reliable characterization of soot particles in flames. The latter needs detailed a priori information about the flame to allow the unique determination of sizes from the diffusion measurements. The soot particles grow monotonously with height above burner and with decreasing air equivalence ratio. The aggregates have a fractal dimension lower than two.
A Predictive Model for the Initial Droplet Size and Velocity Distributions in Sprays and Comparison with Experiments
Authors: Kim Woo Tae , Mitra Sushanta K. , Li Xianguo , Prociw L. A. , Hu T. C. J.
Published: May 2003

The distribution of sizes and velocities of droplets initially formed in sprays is an important piece of information needed in the spray modelling, because it defines the initial condition of the spray droplets in the predictive calculations of the downstream two‐phase flow fields. A predictive model for the initial droplet size and velocity distributions in sprays is formulated in this study. The present model incorporates both the deterministic and the stochastic aspect of spray formation process. The deterministic aspect takes into account of the unstable wave motion before the liquid bulk breakup through the linear and nonlinear instability analysis, which provides information for the liquid bulk breakup length, the mass‐mean diameter and a prior distribution for the droplet sizes corresponding to the unstable wave growth of various wavelengths. The stochastic aspect deals with the final stage of droplet formation after the liquid bulk breakup by statistical means through the maximum entropy principle based on Bayesian entropy. The two sub‐models are coupled together by the various source terms signifying the liquid‐gas interaction, the mass mean diameter and the prior distribution based on the instability analysis. The initial droplet size and velocity distributions are measured experimentally by phase‐Doppler interferometry for sprays generated by a planar research nozzle and a practical gas turbine airblast nozzle. For the two nozzles, the liquid bulk sheet is formed before its breakup in a coflowing air stream. It is found that the model predictions are in satisfactory agreement with the experimental data for all the cases measured. Hence the present model may be applied to a variety of practical sprays to specify the initial conditions for the spray droplets formed in practical spray systems.
Two Heteroleptic Zinc(II) Complexes: [Zn(phen)(C9H15O6)2] and [Zn2(phen)2(H2O)2(C10H16O4)2] · 3H2O
Authors: Zheng Yue‐Qing , Lin Jian‐Li
Published: May 2003

Reactions of a freshly prepared Zn(OH)2‐2x(CO3)x · yH2O precipitate, phenanthroline with azelaic and sebacic acid in CH3OH/H2O afforded [Zn(phen)(C9H15O4)2] (1) and [Zn2(phen)2(H2O)2(C10H16O4)2] · 3H2O (2), respectively. They were structurally characterized by X‐ray diffraction methods. Compound 1 consists of complex molecules [Zn(phen)(C9H15O4)2] in which the Zn atoms are tetrahedrally coordinated by two N atoms of one phen ligand and two O atoms of different monodentate hydrogen azelaato groups. Intermolecular C(alkyl)‐H···π interactions and the intermolecular C(aryl)‐H···O and O‐H···O hydrogen bonds are responsible for the supramolecular assembly of the [Zn(phen)(C9H15O4)2] complexes. Compound 2 is built up from crystal H2O molecules and the centrosymmetric binuclear [Zn2(phen)2(H2O)2(C10H16O4)2] complex, in which two [Zn(phen)(H2O)]2+ moieties are bridged by two sebacato ligands. Through the intermolecular C(alkyl)‐H···O hydrogen bonds and π‐π stacking interactions, the binuclear complex molecules are assembled into layers, between which the lattice H2O molecules are sandwiched. Crystal data: (1) C2/c (no. 15), a = 13.887(2), b = 9.790(2), c = 22.887(3)Å, β = 107.05(1)°, U = 2974.8(8)Å3, Z = 4; (2) P1¯ (no. 2), a = 8.414(1), b = 10.679(1), c = 14.076(2)Å, α = 106.52(1)°, β = 91.56(1)°, γ = 99.09(1)°, U = 1193.9(2)Å3, Z = 1.
Syntheses, Crystal Structures, and Cytotoxicity Evaluation of two Chain‐like and Diamond‐like Silver(I) Complexes
Authors: Zhu Hai‐Liang , Zhang Xian‐Ming , Liu Gao‐Feng , Wang Da‐Qi
Published: May 2003

Two coordination polymers [Ag(dach)]n(NO3)n (1) and [Ag(teda)(F3CSO3)]n (2) (dach = 1, 2‐diaminocyclohexane, teda = 1, 4‐diazabicyclo[2.2.2]octane) have been synthesized and characterized by X‐ray single crystal analysis and cytotoxicity investigation. Compound 1 has a one‐dimensional chain‐like structure which is extended by ligand unsupported Ag···Ag interactions, hydrophobic interaction and hydrogen bonds into a three‐dimensional supramolecular array while compound 2 shows three‐dimensional diamond‐like framework constructed by coordination bonds. The high cytotoxities of these two compounds imply that they are potential candidates for antitumor agents.
Synthese und Kristallstruktur von Terbium(III)‐meta‐Oxoborat Tb(BO2)3 (≡ TbB3O6)
Authors: Nikelski Tanja , Schleid Thomas
Published: May 2003

Das Terbium‐meta‐Oxoborat Tb(BO2)3 (≡ TbB3O6) entsteht einkristallin bei der Reaktion von Terbium, Tb4O7 und TbCl3 mit einem Überschuß von B2O3 in gasdicht verschlossenen Platinampullen nach drei Wochen bei 950 °C. Die Verbindung ist luft‐ und wasserstabil und fällt in langen, dünnen, farblosen Nadeln an, die aufgrund ihres ausgeprägt faserigen Habitus zur Wachstumsverzwillingung neigen. Die Kristallstruktur von Tb(BO2)3 (orthorhombisch, Pnma; a = 1598, 97(9), b = 741, 39(4), c = 1229, 58(7) pm; Z = 16) enthält parallel (100) verlaufende, stark gewellte Oxoborat‐Schichten {(BO2)‐} aus eckenverknüpften [BO4]5‐‐Tetraedern (d(B‐O) = 143‐154 pm, ∢(O‐B‐O) = 102‐115°). Die vier kristallographisch unterschiedlichen Tb3+‐Kationen weisen allesamt Koordinationszahlen von acht gegenüber den Sauerstoffatomen (d(Tb‐O) = 228‐287 pm) auf. Auch die entsprechenden Metallkationenpolyeder [TbO8]13+ treten zu Schichten (Zusammensetzung: {(Tb2O11)16‐}) zusammen, die sich ebenfalls parallel (100) ausbreiten.
Competitive Coordination of the Uranyl Ion by Perchlorate and Water ‐ The Crystal Structures of UO2(ClO4)2·3H2O and UO2(ClO4)2·5H2O and a Redetermination of UO2(ClO4)2·7H2O
Authors: Fischer Andreas
Published: May 2003

By slow evaporation of solutions containing UO2(ClO4)2 and an excess of HClO4, single crystals of [UO2(ClO4)2(H2O)3] (1) and [UO2(H2O)5](ClO4)2 (2) were obtained and their structures were determined. From similar solutions prepared from stoichiometric amounts of UO3 and perchloric acid, crystals of [UO2(H2O)5](ClO4)2·2H2O (3) were obtained. The trihydrate (monoclinic, P21/c, a = 545.44(1) pm, b = 1811.09(5) pm, c = 1032.46(2) pm, β = 90.016(1)°) consists of uranyl ions, which are coordinated by two monodentate perchlorate ions and three water molecules. The pentahydrate (monoclinic, P21/n, a = 529.35(2) pm, b = 1645.43(6) pm, c = 1480.18(6) pm, β = 99.847(1)°) contains uranyl ions coordinated by five water molecules. The same structural unit can be found in the heptahydrate, whose structure was re‐determined (orthorhombic, Pbcn, a = 920.9(3) pm, b = 1067.9(3) pm, c = 1445.7(3) pm). In this structure, two molecules of water of crystallization are present.
Der UCl3‐Typ mit komplexen Anionen und seine Additions‐Substitutions‐Variante: Synthese und Kristallstruktur von Nd(ClO4)3 und Na0, 75Nd0, 75(ReO4)3
Authors: Grupe Sven , Wickleder Mathias S.
Published: May 2003

Fliederfarbene Einkristalle von Nd(ClO4)3 (hexagonal, P63/m, Z = 2, a = 933, 0(1), c = 560, 08(5) pm, Rall = 0, 0422) bilden sich bei vorsichtiger Entwässerung von Nd(ClO4)3·6H2O im Argonstrom bei 220 °C. Hexagonale Einkristalle von Na0, 75Nd0, 75(ReO4)3 (P63/m, Z = 2, a = 1000, 0(1), c = 636, 08(5) pm, Rall = 0, 0206) sind ebenfalls fliederfarben und bilden sich bei der Umsetzung von Nd(ReO4)3 mit einem Überschuß von NaCl bei 820 °C. Phasenreine Pulverpräparate der Verbindung können durch Festkörperreaktion von NaReO4 mit Nd(ReO4)3 in evakuierten Quarzglasampullen erhalten werden.
Solution Mediated Synthesis and Structure of the First Anionic Bis‐( hexaborato)‐Zincate Prepared in the Presence of an Organic Amine
Authors: Natarajan Srinivasan , Klein Wilhelm , Panthöfer Martin , van Wüllen Leo , Jansen Martin
Published: May 2003

A room temperature reaction of zinc acetate, tributyl borate and N, N, N′N′‐tetramethylethylenediamine (tmen) in a mixture of water and 1‐butanol has given rise to a new bis‐(hexaborato)‐zincate, [(Me)2NH(CH2)2NH(Me)2][{Zn(B6O7(OH)6}2]·2H2O (I). The structure, determined by single crystal X‐ray diffraction, (P1, a = 8.3014(2), b = 9.2489(2), c = 10.442(2)Å, α = 107.71(3), β = 94.22(3), γ = 100.02(3)°, V = 749.6(3)Å3 = Z = 1, R1 = 0.0387, wR2 = 0.105), consists of anionic molecular Zn hexaborate units forming a herringbone arrangement, through strong hydrogen bond interactions, with the amine molecule situated between the chains. Compound I is the first bis‐(hexaborato)‐zincate, to our knowledge, that has been synthesized in the presence of an organic amine.
Darstellung, Eigenschaften und Molekülstrukturen von Heterobimetallorganika des vierwertigen Germaniums mit dem 2‐(Dimethylaminomethyl)ferrocenyl‐Liganden FcN (η5‐C5H5)Fe[η5‐C5H3(CH2NMe2)‐2]
Authors: Fischer Axel , Jacob Klaus , Edelmann Frank Thomas
Published: May 2003

Das heterobimetallische Lithiumorganyl [2‐(Dimethylaminomethyl)ferrocenyl]‐Lithium, FcNLi, reagiert mit Germanium(IV)‐chlorid, GeCl4, zu den heterobimetallischen Germaniumorganylen (FcN)nGeCl4‐n (n = 2 (1), 3 (2)). Bei Hydrolysereaktionen von 2 entsteht das heterobimetallische Organogermanol (FcN)3GeOH (3). Die eingehende Charakterisierung von 1—3 erfolgte durch Einkristall‐Röntgenstrukturanalysen sowie durch NMR‐ und Massenspektrometrie.
Alkoxo‐Verbindungen des dreiwertigen Eisen: Synthese und Charakterisierung von [Fe2(OtBu)6], [Fe2Cl2(OtBu)4], [Fe2Cl4(OtBu)2] und [N(nBu)4]2[Fe6OCl6(OMe)12]
Authors: Spandl Johann , Kusserow M. , Brüdgam I.
Published: May 2003

Durch Reaktion von Eisen(III)‐chlorid in Diethylether mit Natrium‐tert‐butylat konnte das homoleptische dimere tert‐Butoxid [Fe2(OtBu)6] (1) hergestellt werden. Die Chloro‐Derivate [Fe2Cl2(OtBu)4] (2) und [Fe2Cl4(OtBu)2] (3) wurden durch Liganden‐Austausch zwischen 1 und Eisen(III)‐chlorid synthetisiert. In 1, 2 und 3 liegen jeweils zwei kantenverknüpfte Tetraeder mit zwei tert‐Butoxo‐Gruppen als Brückenliganden vor. Eine entscheidende Rolle für die Synthese von 1, 2 und 3 spielt das verwendete Lösungsmittel Diethylether, wobei sich primär das Dietherat des Eisen(III)‐chlorids FeCl3(OEt2)2 (4) bildet. Durch Reaktion von Eisen(III)‐chlorid mit Tetrabutylammoniummethoxid in Methanol konnte darüberhinaus ein Chloro‐Methoxo‐Oxo‐Hexaeisen‐Cluster [N(nBu)4]2[Fe6OCl6(OMe)12] (5) mit Tetrabutylammonium als Kation synthetisiert und strukturell charakterisiert werden.
Metallkomplexe naphthyl‐substituierter Thioharnstoffderivate
Authors: Schröder Uwe , Richter R. , Beyer L. , Angulo‐Cornejo J. , Lino‐Pacheco M. , Guillen A.
Published: May 2003

Es wurden das Thioharnstoffderivat N, N‐Diethyl‐N′‐2‐naphthoylthioharnstoff (1) und drei N‐(Dialkylaminothiocarbonyl)‐N′‐(1‐naphthyl)‐arylamidine (2‐4) synthetisiert und mit diesen CuII‐, NiII‐ und PdII‐Komplexe dargestellt. Die röntgenstrukturanalytischen Untersuchungen zeigen, daß 1 mit CuII und NiII unter Deprotonierung neutrale Bischelate von nahezu quadratisch‐planarer Koordination mit einer cis‐Anordnung der O‐ und S‐Ligatoratome bildet. 2‐4 binden in deprotonierter Form über ihre N‐ und S‐Atome in 1, 3‐Stellung an CuII und PdII zu neutralen Bischelaten — im Fall von CuII mit verzerrt tetraedrischer Koordination. PdII wird quadratisch‐planar koordiniert und hat, offenbar aufgrund des sterischen Einflusses der 1‐Naphthylgruppen, eine trans‐Anordnung der N‐ und S‐Ligatoratome.
The Crystal Structure of Ba58Ga22F180O
Authors: Pierrard Angélique , Samouël Maurice , Gredin Patrick , Laval Jean‐Paul , de Kozak Ariel
Published: May 2003

The crystal structure of Ba58Ga22F180O is established by means of X‐ray single crystal diffraction. It is tetragonal: a = 22.033(1) Å, c = 17.626(1) Å, Z = 2. The structure is solved in the space group I4/mmm (n° 139), using 3219 independent reflections. It is mainly built from a deficient arrangement of fluorite‐type [FBa4] tetrahedra connected by edges and vertices which constitutes the skeleton of the structure, giving rise to large cavities in which lie isolated fluorine ions in tetrahedral and octahedral barium environment, isolated [F2Ba6] bitetrahedra, isolated barium ions in eight‐coordination of fluorine and a complex arrangement of isolated [GaF6] octahedra and isolated [Ga2F10O] bioctahedra.
Synthese und Kristallstruktur von [(n‐Bu)4N][W6Cl18]
Authors: Dill Simone , Ströbele Markus , Meyer H.‐Jürgen
Published: May 2003

Synthesis and Crystal Structure of [(n‐Bu)4N][W6Cl18]

Single‐crystals of [(n‐Bu)4N][W6Cl18] were obtained as thin needles by adding methanol to a solution of W6Cl18 and [(n‐Bu)4N]Cl in tetrahydrofuran. The structure was determined by single‐crystal X‐ray diffraction at 210 K. [(n‐Bu)4N][W6Cl18] crystallizes in the monoclinic space group C 2/c with Z = 8 and the lattice parameters a = 2175.6(1) pm, b = 1738.0(1) pm, c = 2160.36(9) pm, and β = 91.680(5) °. The crystal structure contains isolated [(W6Cl12i)Cl6a]— clusters and [(n‐Bu)4N]+ ions.
Synthesis of Ammonium‐ and 4‐Dimethylaminopyridinium Amidofluorophosphates and Crystal Structure of [DMAPH][PO2F(NH2)]
Authors: Sluka Radek , Vavříková Karla , Žák Zdirad , Černík Miloš
Published: May 2003

NH4[PO2F(NH2)] has been prepared by the reaction of a betaine py·PO2F with excess ammonia in acetonitrile solution, while the ammonolysis of DMAP·PO2F with a stoichiometric amount of NH3 yields [DMAPH][PO2F(NH2)]. The crystal structure of the latter was determined by single‐crystal X‐ray diffraction, which revealed that the anions [PO2F(NH2)]— are linked to infinite chains by double N—H···O bridges. Additional strong N—H···O bridging bonds connect each anion with its [DMAPH]+ counterion. The formation of a new betaine NH3·PO2F in the solution of py·PO2F in liquid ammonia was proved by 31P NMR spectroscopy and by identification of its hydrolysis products.
Voltammetric and Spectroscopic Study of Chromium(III)/Picolinate Complexes
Authors: Parajón‐Costa Beatriz S. , Wagner Claudia C. , Baran Enrique J.
Published: May 2003

The electrochemical properties and the stability of the CrIII complexes [Cr(pic)3]·H2O and [Cr(pic)2(OH)]2·5H2O (Hpic = pyridine‐2‐carboxylic acid = picolinic acid) were investigated in DMF solutions by cyclic voltammetry, and complemented by electronic spectroscopy. The electrochemical results indicate that both compounds undergo a one‐electron reversible reduction process. The mononuclear species has a more accessible reduction potential than the binuclear one. In this last case, the observed one‐electron process can be ascribed to a considerable stabilization of the mixed valence CrIII/CrII species. Both complexes were also characterized by infrared and Raman spectroscopy.
Magnetic Exchange Interactions in Dinuclear Copper(II) and Nickel(II) Complexes with μ‐Oxalato Bridges. The Structure of μ‐Oxalato(O, O′, O″, O‴)‐bis{[1, 8‐di(2‐pyridyl)‐3, 6‐dithiaoctane‐N, N′, S, S′]nickel(II)} Dinitrate Dihydrate
Authors: Castiñeiras Alfonso , Domínguez Ricardo , Gómez‐Rodríguez Lourdes , Borrás Joaquín
Published: May 2003

A copper(II) and two nickel(II) dinuclear oxalato‐bridged compounds of formulae [{Cu(bpdto)}2(μ‐ox)](ClO4)2 (1), [{Ni(bpdto)]2(μ‐ox)](ClO4)2(2), and [{Ni(bpdto)}2(μ‐ox)](NO3)2·2H2O (3), where bpdto = 1, 8‐bis(2‐pyridyl)‐3, 6‐dithiaoctane and ox = oxalate = C2O42— anion, have been synthesized and characterized. The crystal structure of 3 was determined by single‐crystal X‐ray analysis. It is a dinuclear complex with i symmetry in which the oxalate ligand is coordinated in bis(didentate) fashion to the inversion centre‐related nickel atoms. The distorted octahedral environment of each nickel atom is completed by two sulphur atoms in the equatorial plane and by two pyridyl nitrogen atoms in axial positions. Magnetic susceptibility measurements over the range 5 — 299K, show antiferromagnetic interactions that are weak in 1 (J = —12.8 cm—1) and strong in 2 and 3 (J = —37.8 and —40.9 cm—1, respectively), which in the case of 3 is in keeping with the observed structural parameters.
Mercurous Dimethylglyoximato Nitrate, Hg2(Dmg)2(NO3)2
Authors: Nockemann Peter , Meyer Gerd
Published: May 2003

Colourless needles of mercurous dimethylglyoximato nitrate, Hg2(Dmg)2(NO3)2, grow from a diluted nitric acid solution of mercurous nitrate and dimethylglyoxime. The crystal structure (triclinic, P1¯, a = 728.50(13), b = 1066.8(2), c = 1167.9(2) pm, α = 93.78(2)°, β = 94.16(2)°, γ = 98.61(2)°, Rall = 0, 0726) contains the cations [Hg2(Dmg)2]2+ and “non‐coordinating” (NO3)— anions. In the cation, two neutral dimethylglyoxime molecules coordinate bidentately with Hg—N distances in the narrow range of 236 to 239 pm to the mercurous ion, Hg22+, which exhibits a Hg—Hg bond distance of 252.23(8) pm).
Hg2(OH)[BF4], the First Basic Mercurous Tetrafluoroborate
Authors: Göbbels Dirk , Meyer Gerd
Published: May 2003

The first basic mercurous tetrafluoroborate, Hg2(OH)[BF4], was obtained through a synproportionation reaction of red mercuric oxide, HgO, and elemental mercury in a 35% solution of HBF4 in water as colourless single crystals. The crystal structure (orthorhombic, Pbca, Z = 8, a = 985.0(1), b = 991.0(1), c = 1141.0(2) pm) contains [(HO)1/2—Hg—Hg—(OH)1/2]+ zig‐zag chains that are further connected via weak Hg—OH interchain interactions to layers between which the [BF4]— are located in an up and down fashion.
Synthese und Molekülstrukturen von amido‐ und imidoverbrückten Clustern elektronenreicher Übergangsmetalle
Authors: Link Holger , Reiss Peter , Chitsaz Soheila , Pfistner Heike , Fenske Dieter
Published: May 2003

Wir berichten in diesem Article über Ergebnisse, die im Rahmen des DFG‐Schwerpunktprogramms “Nitridobrücken zwischen Übergangsmetallen und Hauptgruppenelementen” erhalten wurden. Durch Reaktionen von elektronenreichen Übergangsmetallverbindungen mit stannylierten bzw. lithiierten Derivaten des Stickstoffs in Anwesenheit von Phosphanen erhält man in unterschiedlichen organischen Lösungsmitteln eine große Anzahl von stickstoffverbrückten Übergangsmetallclustern. Die Strukturen der Verbindungen 1 — 27 konnten durch Einkristall‐Röntgenstrukturanalyse aufgeklärt werden.
Transition Metal Complexes Containing Functionalized Organoimido and Phosphaneiminato Ligands
Authors: Siemeling U. , Kölling L. , Kuhnert O. , Neumann B. , Stammler A. , Stammler H.‐G. , Fink G. , Kaminski E. , Kiefer A. , Schrock R. R.
Published: May 2003

Two different types of modified imido and phosphaneiminato ligands are investigated, namely chelate ligands and redox‐functionalised ligands. The first examples of di(organoimido)chromium as well as di(phosphaneiminato)titanium and niobium chelates are described. Furthermore, the first complexes containing redox‐functionalised organoimido ligands are presented, together with the first structurally characterised redox‐functionalised phosphaneiminato complex. Compounds of the type [(RN)2M(CH2Ph)2] (M = Cr, Mo) are used as catalysts for the (co‐)polymerisation of the polar olefins methyl methacrylate, acrylonitrile and vinyl acetate. A range of X‐ray crystal structure determinations provide clear evidence for the quantum‐chemical result that, similar to organoimido complexes, the potential energy well for the angle at the nitrogen atom is very shallow for phosphaneiminato complexes.
2‐Iminoimidazoline — starke Stickstoffbasen als Koordinationspartner in der Anorganischen Chemie
Authors: Kuhn Norbert , Göhner Martin , Grathwohl Martin , Wiethoff Jörg , Frenking Gernot , Chen Yu
Published: May 2003

2‐Iminoimidazoline weisen, bedingt durch die Tendenz des Fünfringfragments zur Übernahme einer positiven Formalladung und die hieraus resultierende Ylid‐artige Bindungssituation, eine hohe Stickstoff‐Basizität auf; sie können als Neutral‐liganden, als 2+2‐Elektronendonatoren fungieren. Durch Deprotonierung sind hieraus die zugehörigen Anionen als potentielle 2+4‐Elektronendonatoren zugänglich.

Wir beschreiben zunächst die Synthese und Charakterisierung der Titelverbindung 2‐Imino‐1, 3‐dimethylimidazolin (ImNH, 8) und ihres Anions 9. Nachfolgend werden deren Ligandeigenschaften an ausgewählten Beispielen der Koordinationsverbindungen der Haupt‐ und Nebengruppenelemente demonstriert. In einem dritten Abschnitt stellen wir Versuche zur Funktionalisierung der Iminoimidazoline vor in der Absicht, durch die Konstruktion hemilabil koordinierender Neutralliganden einen Beitrag zur katalyseorientierten Komplexchemie zu leisten.

Die Ergebnisse von MO‐Berechnungen zur Interpretation der Bindungssituation werden experimentellen Befunden gegenübergestellt.
On the Donor Ability of the Phosphaneiminato Substituent and Cube Formation with Transition Metal Fragments
Authors: Schoeller Wolfgang W.
Published: May 2003

The particular role of the phosphaneiminato ligand as a donor is investigated for a) nitrenes (phosphinidenes) and carbenes and b) cubane formation with transition metals. Accordingly, and as shown for the case a) the ligand is a stronger π‐donor than an amino group and can be considered as a special case of imine‐type substituents. The latter are very effective in π‐donation. In the case b), i.e. the cubane formation with transition metals, one has to consider transition metals with a partially or completely filled d‐shell (with electrons). Hence depending on the transition metal, cubanes are build with weak ferromagnetic coupled or closed shell systems. For the cubanes with closed shell character the matter of insertion of halide anions is discussed. In the last chapter of the review the bond stretching in the dithionitrosyl complexes with rhenium is characterized.
Pentamethylcyclopentadienyl Halfsandwich Complexes of Vanadium and Tantalum with Amido‐, Imido‐ Nitrido‐ and Azido Ligands
Authors: Herberhold Max , Dietel Anna‐Maria , Goller Achim , Milius Wolfgang
Published: May 2003

Lithium bis(trimethylsilyl)amide, LiN(SiMe3)2, reacts with Cp*V(O)Cl2 and Cp*TaCl4 to give trimethylsilylimido complexes such as [Cp*V(NSiMe3)(μ‐NSiMe3)]2 (7) and Cp*Ta(Cl)(NSiMe3)[N(SiMe3)2] (19), respectively. Substitution of the chloro ligand in 19 by anionic groups leads to complexes with 3 different N‐containing ligands, Cp*Ta(X)(NSiMe3)[N(SiMe3)2] (X = N3 (20) or NPEt3 (21)).

Complex 7 is air‐ and moisture‐sensitive, and several derivatives containing oxo and trimethylsiloxy ligands have been identified. Trimethylsilyl azide, Me3Si‐N3, is able to replace the oxygen‐containing ligands for azido ligands. The two complete series of bis(azido)‐bridged complexes, [Cp*VCln(N3)2‐n(μ‐N3)]2 (n = 2, 1, 0) and [Cp*TaCln(N3)3‐n(μ‐N3)]2(n = 3, 2, 1, 0), are accessible from the reactions of Cp*VCl3 and Cp*TaCl4, respectively, with trimethylsilyl azide.

A bis(nitrido)‐bridged azido‐vanadium complex, [Cp*V(N3)(μ‐N)]2 (18), has also been obtained and structurally characterized.
Oligonary Nitrides and Oxonitrides of Si, P, Al, and B in Combination with Rare Earth or Transition Metals as well as Molecular Precursor Compounds with Nitrido Bridges M‐N‐Si (M = Ti, Zr, Hf, W, Sn)
Authors: Schnick Wolfgang , Bettenhausen Regina , Götze Brigitte , Höppe Henning A. , Huppertz Hubert , Irran Elisabeth , Köllisch Klaus , Lauterbach Rainer , Orth Michael , Rannabauer Stefan , Schlieper Thomas , Schwarze Bernd , Wester Frank
Published: May 2003

A novel synthetic approach is presented leading to hitherto unknown nitridosilicates, oxonitridosilicates, oxonitridoaluminosilicates, carbidonitridosilicates, as well as nitridoborates and oxonitridoborates of rare earth elements, alkali, and alkaline earth metals. Typically, the respective metals were reacted with silicon diimide, aluminum nitride, or poly(boron amide imide), respectively, under pure nitrogen atmosphere utilizing a radiofrequency furnace. Usually, the compounds are obtained within short reaction periods as coarsely crystalline products. Zink nitridophosphates of the sodalite structure type were obtained by the reaction of phosphorus nitride imide with zinc or zinc chalcogenides, respectively. Several molecular metal silylamides and imides containing nitridobridges between the metals and silicon were obtained by the reaction of differently chlorinated disilazanes with metal chlorides. During these investigations hitherto unknown bis(trimethylsilyl)ammonium salts have been discovered. Furthermore, we report about the synthesis of N‐silyl metal hydrazides.
Präkeramische Polyazane über die Sol‐Gel‐Route im Ammonosystem und aus molekularen Einkomponentenvorläufern — ein Leistungsvergleich
Authors: Engering Josef , Jansen Martin
Published: May 2003

Der Sol‐Gel‐Prozess im Oxosystem lässt sich in allen Schritten analog auf das Ammonosystem übertragen. Dazu werden Elementalkylamide von Titan, Zirkonium, Tantal und Bor einerseits und Silicium andererseits in aprotischen Lösungsmitteln kontrolliert co‐ammonolysiert. Bei der Pyrolyse der so erhaltenen Polyazane entstehen multinäre, nitridische Keramikpulver. In den Modellsystemen Si(NHMe)4/Ti(NMe2)4, Si(NHMe)4/Zr(NMe2)4, Si(NHMe)4/Ta(NMe2)5 und Si(NHMe)4/B(NMe2)3, wurden polymere Polyboro‐, Polytitano‐, Polyzirkono‐ und Polytantalosilazane dargestellt. Pyrolyse im Ammoniak‐Strom bis 1000°C liefert ternäre amorphe Siliciumnitride; weiteres Tempern im Stickstoffstrom bei 1500°C ergibt partiell kristalline Komposite. Sowohl Struktur und Verlauf der Pyrolyse der polymeren Zwischenstufen als auch die Morphologie und Zusammensetzung der Pyrolyseprodukte wurden mit NMR, MAS‐NMR, FT‐IR, DTA‐TG‐MS, XRD, REM, EDX und Elementanalyse untersucht.

Für eine Referenzierung des neu entwickelten, einfachen Zugangs zu multinären nitridischen Keramiken wurden für die gleichen Systeme Einkomponentenvorläufer dargestellt und über Polymere zu keramischen Pulvern pyrolysiert. Zu diesem Zweck wurde eine Reaktionsfolge ausgearbeitet, die verallgemeinerbar für die Darstellung von Einkomponentenvorläufern ist und für verschiedene ternäre Metallsiliciumnitride eingesetzt werden kann. Dilithiierte Silazane vom Typ Si(NMe2)2(NLiR)2 mit R = t‐Butyl, SiMe3, CH3, erstmals dargestellt und strukturell charakterisiert, sind gute Silicium‐Synthone, die mit vorzugsweise zwei‐ oder vierwertigen Übergangsmetallchloriden unter Ausbildung von Nitridobrücken zu Silicium‐Übergangsmetall‐Addukten reagieren. Konkret wurden die Reaktionen von Si(NMe2)2(NLiR)2 mit TiCl4, ZrCl4, TaCl5, CrCl3, MnCl2, und ZnCl2 untersucht und die gebildeten Addukte mit Ammoniak vernetzt und pyrolysiert. Im Falle der Metallchloride der 4.—6. Nebengruppe entstanden amorphe Keramikpulver bzw. bei höherer thermischer Belastung Komposite aus Übergangsmetallnitrid und amorpher Matrix. In den Systemen Mn/ Si/ N und Zn/ Si/ N wurden MnSiN2 und eine neue hexagonale Phase von ZnSiN2 einphasig erhalten. In einer Nebenreaktion entsteht im letzteren Fall völlig unerwartet ZnCN2 neben ZnSiN2.
Relationship of knee joint proprioception to pain and disability in individuals with knee osteoarthritis
Authors: Bennell Kim L. , Hinman Rana S. , Metcalf Ben R. , Crossley Kay M. , Buchbinder Rachelle , Smith Michael , McColl Geoffrey
Published: May 2003

Proprioception plays an integral role in neuromotor control of the knee joint and deficits in knee joint proprioception are well documented in individuals with knee osteoarthritis (OA). However, the functional relevance of these deficits is not clear. This crosssectional study evaluated the relationship between knee joint proprioception and pain and disability in a large cohort of individuals with knee OA. Two hundred and twenty participants (145 F, 75 M) with symptomatic knee OA were recruited from the community. Five non‐weight bearing active tests with ipsilateral limb matching responses were performed at 20° and 40° flexion to measure knee joint position sense. Pain and disability were assessed by self‐reported questionnaires and objective measures of balance and gait. Results showed little association between knee joint position sense variables and measures of pain and disability (r values <0.24, most p > 0.05). When comparing participants with the worst and best joint position sense, no significant differences in pain and disability could be found (p > 0.05). While our study design does not allow causality to be established, these results suggest that deficits in joint position sense may be due to factors other than pain and that deficits are not large enough to impact upon disability. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Use of volumetric computerized tomography as a primary outcome measure to evaluate drug efficacy in the prevention of peri‐prosthetic osteolysis: A 1‐year clinical pilot of etanercept vs. placebo
Authors: Schwarz Edward M. , Campbell Debbie , Totterman Saara , Boyd Allen , O'Keefe Regis J. , Looney R. John
Published: May 2003

Although total hip replacement (THR) is amongst the most successful and beneficial medical procedures to date, long‐term outcomes continue to suffer from aseptic loosening secondary to peri‐prosthetic osteolysis. Extensive research over the last two decades has elucidated a central mechanism for osteolysis in which wear debris generated from the implant stimulates inflammatory cells to promote osteoclastogenesis and bone resorption. The cytokine tumor necrosis factor alpha (TNFα) has been demonstrated to be central to this process and is considered to be a leading target for intervention. Unfortunately, even though FDA approved TNF antagonists are available (etanercept), currently there are no reliable outcome measures that can be used to evaluate the efficacy of a drug to prevent peri‐prosthetic osteolysis. To the end of developing an effective outcome measure, we evaluated the progression of lesion size in 20 patients with established peri‐acetabular osteolysis (mean = 29.99 cm3, range = 2.9–92.7 cm3) of an uncemented primary THR over 1‐year, using a novel volumetric computer tomography (3D‐CT) technique. We also evaluated polyethylene wear, urine N‐telopeptides and functional assessments (WOMAC, SF‐36 and Harris Hip Score) for comparison. At the time of entry into the study baseline CT scans were obtained and the patients were randomized to etanercept (25 mg s.q., twice/week) and placebo in a double‐blinded fashion. CT scans, urine and functional assessments were also obtained at 6 and 12 months. No serious adverse drug related events were reported, but one patient had to have revision surgery before completion of the study due to aseptic loosening. No remarkable differences between the groups were observed. However, the study was not powered to see significant drug effects. 3D‐CT data from the 19 patients was used to determine the mean increase in lesion size over 48 weeks, which was 3.19 cm3 (p < 0.0013). Analysis of the urine N‐telopeptides and functional assessment data failed to identify a significant correlation with wear or osteolysis. In conclusion, volumetric CT was able to measure progression of osteolysis over the course of a year, thus providing a technology that could be used in therapeutic trials. Using the data from this pilot we provide a model power calculation for such a trial. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Bone architecture and disc degeneration in the lumbar spine of mice lacking GDF‐8 (myostatin)
Authors: Hamrick Mark W. , Pennington Catherine , Byron Craig D.
Published: May 2003

GDF‐8, also known as myostatin, is a member of the transforming growth factor‐β superfamily of secreted growth and differentiation factors that is expressed in vertebrate skeletal muscle. Myostatin functions as a negative regulator of skeletal muscle growth and myostatin null mice show a doubling of muscle mass compared to normal mice. We describe here morphology of the lumbar spine in myostatin knockout (Mstn‐/‐) mice using histological and densitometric techniques. The Mstn‐/‐ mice examined in this study weigh approximately 10% more than controls (p < 0.001) but the iliopsoas muscle is over 50% larger in the knockout mice than in wild‐type mice (p < 0.001). Peripheral quantitative computed tomography (pQCT) data from the fifth lumbar vertebra show that mice lacking myostatin have approximately 50% greater trabecular bone mineral density (p = 0.001) and significantly greater cortical bone mineral content than normal mice. Toluidine blue staining of the intervertebral disc between L4–L5 reveals loss of proteoglycan staining in the hyaline end plates and inner annulus fibrosus of the knockout mice. Loss of cartilage staining in the caudal end plate of L4 is due to ossification of the end plate in the myostatin‐deficient animals. Results from this study suggest that increased muscle mass in mice lacking myostatin is associated with increased bone mass as well as degenerative changes in the intervertebral disc. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
cDNA‐arrays and real‐time quantitative PCR techniques in the investigation of chronic achilles tendinosis
Authors: Alfredson Håkan , Lorentzon Mattias , Bäckman Stina , Bäckman Assar , Lerner Ulf H
Published: May 2003

The aetiology and pathogenesis of chronic painful Achilles tendinosis are unknown. This investigation aimed to use cDNA arrays and real‐time quantitative polymerase chain reaction (real‐time PCR) technique to study tendinosis and control tissue samples. Five patients (females mean age 57.1 ± 4.3 (years ±SD)) with chronic painful Achilles tendinosis were included. From all patients, one biopsy was taken from the area with tendinosis and one from a clinically normal area (control) of the tendon. The tissue samples were immediately immersed in RNAlater and frozen at –80°C until RNA extraction. Portions of pooled RNA from control and tendinosis sites, respectively, were transcribed to cDNA, radioactively labelled (32P), hybridized to cDNA expression arrays, and exposed to phosphoimager screens over night. Expressions of specific genes, shown to be regulated in the cDNA array analysis, were analyzed in the individual samples using real‐time PCR. cDNA arrays showed that gene expressions for matrix‐metalloproteinase‐2 (MMP‐2), fibronectin subunit B (FNRB), vascular endothelial growth factor (VEGF), and mitogen‐activated protein kinase p38 (MAPKp38) were up‐regulated, while matrix‐metalloproteinase‐3 (MMP‐3) and decorin were down‐regulated, in tendinosis tissue compared with control tissue. Using real‐time PCR, ⅘ and ⅗ patients showed up‐regulation of MMP‐2 and FNRB mRNA, respectively. For decorin, VEGF, and MAPKp38, real‐time PCR revealed a great variability among patients. Interestingly, the mRNAs for several cytokines and cytokine receptors were not regulated, indicating the absence of an inflammatory process in chronic painful Achilles tendinosis. In conclusion, cDNA‐arrays and real‐time PCR can be used to study differences in gene expression levels between tendinosis and control tendon tissue. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Factors That Influence Smoking in Adolescent Girls
Authors: Faucher Mary Ann
Published: May 2003

A secondary analysis of data from the public‐use version of the National Longitudinal Study of Adolescent Health (Add Health) was used for this research study. Variables and constructs that significantly influence smoking in adolescent girls are identified. These variables and constructs include residential mother‐daughter connectedness, self‐concept, residential mother's smoking behavior, and friends' smoking behavior. All variables and constructs identified are significantly associated with smoking in white adolescent girls. Residential mother‐daughter connectedness and friends' smoking behavior are significantly associated with smoking in black adolescent girls. Friends' smoking behavior is the only variable in this study found to be significantly associated with smoking in Hispanic adolescent girls. Results of this secondary analysis suggest that the influential and protective factors related to smoking vary with race/ethnicity.
Adolescents' Experiences of Dating and Intimate Partner Violence: “Once Is Not Enough”
Authors: Scheiman Lisa , Zeoli April M.
Published: May 2003

Pregnant and parenting adolescents represent a significant proportion of the individuals directly affected by intimate partner violence. Although screening tools are useful, it is important to ask very specific questions to open lines of communication with adolescents. This article presents a clinical case that highlights the challenges of screening adolescents for intimate partner violence and offers suggestions for health care providers. Specific examples of screening questions are offered.