bluuebunny/crossref_metadata_2025 huggingface dataset:
Umweltverträgliche Verschleißschutzkonzepte für Wälzlager im Mischreibungsgebiet
Authors: Gold P. W. , Loos J. , Kuhn M.
Published: October 2004

Die Effektivität des Verschleißschutzes von im Mischreibungsgebiet betriebenen Wälzlagern wird durch den Einsatz von EP/AW‐Schmierstoffadditiven immens gesteigert. Ziel umfangreicher Versuche und Untersuchungen innerhalb des SFB 442 ist der Betrieb eines umweltverträglichen Tribosystems Wälzlager, in dem die Aufgaben der teilweise hoch umweltschädlichen Additive auf die Wälzpartneroberflächen übertragen werden. Der Einsatz eines entfeinerten, biologisch schnell abbaubaren Schmierstoffes soll so ermöglicht werden. Dazu wird systematisch am Beispiel von verschleißkritischen Axial‐Zylinderrollenlagern gezeigt, dass PVD‐Beschichtungen in der Lage sind, Wälzlager optimal vor Verschleiß zu schützen. Auch ein neu entwickelter, biologisch schnell abbaubarer Esterschmierstoff beweist eine erhebliche Steigerung des Verschleißschutzes im Vergleich zum Mineralöl geschmierten Referenzversuch. Die Kombination beider Komponenten, PVD‐Schicht und umweltverträglicher Schmierstoff, zeigt im Versuch, dass die beschichteten Lageroberflächen keinen nennenswerten Verschleiß aufweisen. Die Beschichtung der Scheiben hat jedoch bei Esterschmierung im Gegensatz zur Mineralölschmierung keinen Verschleiß schützenden Einfluss auf die unbeschichteten Wälzkörper. Insgesamt kann das umweltverträgliche Tribosystem sein sehr hohes Verschleißschutzpotential unter Beweis stellen.
Produktionsintegrierter Umweltschutz bei der Herstellung von Schmierstoffen
Authors: Eisenträger A. , Brinkmann C. , Michel K. , Dott W.
Published: October 2004

Entsprechend den zu erwartenden Änderungen in der europäischen Chemikalienpolitik wird eine Strategie entwickelt, wie ökotoxikologische Untersuchungen frühzeitig in den Entwicklungsprozess neuer Schmierfluide integriert werden können. Es wird gezeigt, dass weder die Testung der Einzelkomponenten noch theoretische Vorhersagen zur Mischungstoxizität alleine ausreichend sind, um das ökotoxische Potential von Schmierfluid‐Formulierungen sicher zu bestimmen. Durch praktische Versuche mit verschiedenen Schmierstoffadditiven, einem Grundöl und Formulierungen aus diesen wird ein möglicher Weg aufgezeigt, mit dem schrittweise das Ziel eines optimierten Schmierfluids auch aus toxikologischer Sicht erreicht werden kann. Die Ergebnisse aus den biologischen Untersuchungen werden durch chemisch‐analytische Daten ergänzt. Dass die Testung der Einzelsubstanzen und die Berechnung von Mischungstoxizitäten zu anderen Schlussfolgerungen führen als das direkte Testen dieser Mischungen, wird anhand von Schmierstoffen auf Basis synthetischer Ester und Additiven nachgewiesen. Insgesamt soll dieser Ansatz als Beispiel dafür dienen, wie „produktionsintegrierter Umweltschutz”︁ hinsichtlich ökotoxikologischer Fragestellungen gerade durch die Verwendung einfacher und schneller Testmethoden umgesetzt werden kann.
Reibungs‐ und Verschleißverhalten von trockenlaufenden Kunststoff/Stahl‐Paarungen
Authors: Müller F. , Deters L.
Published: October 2004

Gegenwärtig erfolgt die Bewertung der Leistungsfähigkeit von polymeren Gleitwerkstoffen mit Hilfe von pU‐Diagrammen oder noch einfacher mittels zulässiger pU‐Kennwerte. Diese Bewertungsparameter geben jedoch nur die Beanspruchungsgrenze der untersuchten Paarung auf der jeweils verwendeten Prüfeinrichtung wieder.

Ziel der Untersuchung war die Bereitstellung von praxisrelevanten Bewertungskriterien für trockenlaufende Kunststoff/Stahl‐Paarungen und zwar auf der Basis von Kennzahlen. Hierzu wurden zunächst, aufbauend auf einer Dimensionsanalyse problemrelavante Kennzahlen herausgearbeitet und anschließend Versuche mit POM und glasfaserverstärktem PA6/6T auf einem Stift‐Scheibe‐Tribometer durchgeführt, aber auch Versuche auf Original‐Gleitlagerprüfständen.

Es werden Temperatur‐, Verschleiß‐ und Reibungszahlverläufe dargestellt, und ein brauchbares Ausfallkriterium präsentiert.

Es wird außerdem eine Vorgehensweise vorgestellt, die es ermöglicht, das Reibungsverhalten derartiger Paarungen anhand einer Kennzahlengleichung, die temperaturabhängige Materialkennwerte, Belastungs‐ und Geometriekenngrößen beinhaltet, vorherzubestimmen. Desweiteren wird eine Möglichkeit zur Verschleißberechnung auf energetischer Basis und die Übertragbarkeit der Erkenntnisse auf reale Anwendungsfälle aufgezeigt.
Pathological situations characterized by altered actin isoform expression
Authors: Chaponnier Christine , Gabbiani Giulio
Published: October 2004

Modulation of actin isoform expression is a well‐established feature of developmental phenomena. As one might expect, it is also characteristic of several pathological situations that are the subject of the present review. α‐Smooth muscle actin has proven to be a reliable marker for identifying (a) vascular smooth muscle cells during vascular development and vascular diseases, and (b) myofibroblasts during wound healing, fibrocontractive diseases, and stromal reaction to epithelial tumours. The hallmark of a differentiated myofibroblast relies on the acquisition of an organized contractile apparatus characterized by α‐smooth muscle actin‐expressing stress fibres. More and more data suggest that α‐smooth muscle actin plays a direct role in myofibroblast contractile activity through its N‐terminal domain AcEEED. Newly developed antibodies against α‐skeletal and α‐cardiac actins have allowed the detection of subpopulations of α‐skeletal positive cardiomyocytes in adult, hypertrophic, and failing heart. These antibodies have also permitted us to identify the differentiation degree of malignant cells in tumours such as rhabdomyosarcoma. Whether the differential expression of actin isoforms in human diseases is functionally relevant is not yet fully established, although studies on human actin mutations, actin null mice, and the N‐terminal end of α‐smooth muscle actin support this possibility. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Keratins and skin disorders
Authors: Lane EB , McLean WHI
Published: October 2004

The association of keratin mutations with genetic skin fragility disorders is now one of the best‐established examples of cytoskeleton disorders. It has served as a paradigm for many other diseases and has been highly informative for the study of intermediate filaments and their associated components, in helping to understand the functions of this large family of structural proteins. The keratin diseases have shown unequivocally that, at least in the case of the epidermal keratins, a major function of intermediate filaments is to provide physical resilience for epithelial cells. This review article reflects on the variety of phenotypes arising from mutations in keratins and the reasons for this variation. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Keratin mutations and intestinal pathology
Authors: Owens DW , Lane EB
Published: October 2004

Whilst the importance of mutations in a wide range of keratins in skin fragility disorders is now well established, there is much less evidence for simple epithelial keratin involvement in disease. Some simple epithelial keratin mutations have been reported in liver cirrhosis and pancreatitis patients, and recently mutations in the simple epithelial keratin K8 were identified in a group of patients with inflammatory bowel disease (Crohn disease or ulcerative colitis). In comparison with the mutations seen in epidermal keratins, these simple epithelial mutations would be predicted to have mild consequences, although analysis shows that they do have a distinct effect. This review article discusses the evidence that these mutations are a predisposing factor for inflammatory bowel disease. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Congenital myopathies: diseases of the actin cytoskeleton
Authors: Clarkson Emilie , Costa Celine F , Machesky Laura M
Published: October 2004

Congenital myopathies are clinical and genetic heterogeneous disorders characterized by skeletal muscle weakness ranging in severity. Three major forms have been identified: actin myopathy, intranuclear rod myopathy, and nemaline myopathy. Nemaline myopathy is the most common of these myopathies and is further subdivided into seven groups according to severity, progressiveness, and age of onset. At present, five genes have been linked to congenital myopathies. These include α‐actin (ACTA1), α‐ and β‐tropomyosin (TPM3 and TPM2), troponin T (TNNT1), and nebulin (NEB). Their protein products are all components of the thin filament of the sarcomere. The mutations identified within these genes have varying impacts on protein structure and give rise to different forms of congenital myopathies. Greater understanding of muscle formation and cause of disease can be established through the study of the effect of mutations on the functional proteins. However, a major limitation in the understanding of congenital myopathies is the lack of correlation between the degree of sarcomeric disruption and disease severity. Consequently, great difficulty may be encountered when diagnosing patients and predicting the progression of the disorders. There are no existing cures for congenital myopathies, although improvements can be made to both the standard of living and the life expectancy of the patient through various therapies. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Wiskott–Aldrich syndrome protein and the cytoskeletal dynamics of dendritic cells
Authors: Calle Yolanda , Chou Hsiu‐chuan , Thrasher Adrian J , Jones Gareth E
Published: October 2004

The regulated migration and spatial localization of dendritic cells in response to environmental signals are critical events during the initiation of physiological immune responses and maintenance of tolerance. Cells deficient in the Wiskott–Aldrich syndrome protein (WASP) have been used to demonstrate the importance of the dynamic remodelling of the actin‐based cytoskeleton during the selective adhesion and migration of these cells. Unlike most cell types, macrophages, dendritic cells, and osteoclasts utilize a specialized adhesive array termed the podosome in order to migrate. Podosomes are composed of many of the same structural and regulatory proteins as seen in the more commonly found focal adhesion, but are unique in their requirement for WASP. Without WASP, podosomes cannot form and the affected cells are obliged to use focal adhesions for their migratory activities. Once activated by a series of upstream regulatory proteins, WASP acts as a scaffold for the binding of the potent actin nucleating protein complex known as Arp2/3. This article reviews the available evidence that suggests that failures in the regulation of the actin cytoskeleton may contribute significantly to the immunopathology of the Wiskott–Aldrich syndrome. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
A method to predict triaxial residual stresses in plastic pipes
Authors: Guan Z. W. , Boot J. C.
Published: October 2004

Significant hoop and longitudinal stresses are present in medium‐density polyethylene (MDPE) pipe, arising from differential cooling from the inner and the outer surfaces of a pipe during production. Owing to the difficulty of directly measuring deformations, these stresses have hitherto been almost exclusively estimated indirectly from deflection measurements on large samples cut from the pipe wall. Furthermore, because of procedural problems, only uniaxial hoop or longitudinal stresses are normally attempted, and these are known to be specimen size–dependent. Similar problems are experienced with other polymeric pipes. In this paper, based on direct biaxial strain measurements on small samples cut from the pipe wall, a method to predict triaxial residual stress distributions through the pipe wall is presented. Thermal effects that generate residual stresses in plastic pipe were considered in the theory. The analytical solutions satisfy the self‐equilibrating conditions for both the hoop and the longitudinal stresses. Also, the radial stress is shown to be insignificant through the wall thickness of a mildly thick pipe. Polym. Eng. Sci. 44:1828–1838, 2004. © 2004 Society of Plastics Engineers.
Thermal properties and crystallization behavior of polyolefin ternary blends
Authors: Ha Man Ho , Kim Byung Kyu
Published: October 2004

Crystallization behaviors, spherulite growth and structure, and the crystallization kinetics of polypropylene (PP)/ethylene‐α‐olefln copolymer (mPE)/high‐density polyethylene (HDPE) ternary blends and of mPE/HDPE binary blends have been studied using polarizing optical micrography (POM) and differential scanning calorimetry (DSC). In mPE/HDPE blends, large pendant groups of mPE disturbed spherulite growth of HDPE, leading to a different crystallite morphology and isothermal kinetics. Non‐isothermal properties, morphology, and isothermal crystallization kinetics of PP in ternary blends were significantly influenced by the composition and crystallization behavior of the mPE/HDPE binary blends as well as the crystallization condition. Polym. Eng. Sci. 44:1858–1865, 2004. © 2004 Society of Plastics Engineers.
Cold forging method for polymer microfabrication
Authors: Yao Donggang , Nagarajan Pratapkumar
Published: October 2004

A polymer micro cold forging process was investigated. This method, derived from polymer solid‐phase forming, resembles more the metal‐forging method than the standard thermoplastic molding protocol. A micro‐forging die set was designed and fabricated and a series of cold forging experiments were carried out with varied process conditions, including forging speed, forging pressure, and dwell time. High‐aspect‐ratio microchannels were fabricated on polytetrafluoroethylene (PTFE) substrates. The dimension of replicated channels was found to be consistent from shot to shot. Owing to instantaneous elastic recovery, the channel has a width about 30% smaller than that on the die. The final channel size is contingent upon the forging process conditions, as well as upon the post‐recovery process. Upsetting experiments of PTFE cylindrical samples were carried out to study the fundamental issues on dimensional recovery so as to predict and consequently control the dimensional changes in polymer cold forging. Polym. Eng. Sci. 44:1998–2004, 2004. © 2004 Society of Plastics Engineers.
Kinetics and modeling of the diffusion‐controlled diallyl terephthalate polymerization
Authors: Hace Iztok , Golob Janvit , Krajnc Matjaž
Published: October 2004

Free radical polymerization kinetics of diallyl terephthalate in bulk was investigated in a wide temperature range from 50°C to 150°C with four different peroxide initiators. Conversion points were measured using Fourier Transform Infrared (FTIR) measurements. The initiator efficiencies and the initiator decomposition rate constants were evaluated from special experiments, applying the theory of dead end polymerization. In addition, the ratios between the degradative and the effective kinetic rate constants to propagation rate constants were obtained from molecular weight measurements at various initiator concentrations. The ratio of chemically controlled termination and propagation rate constant k/ktc of the polymerization system was obtained using the initial rates of polymerization and the number average molecular weight data between 0.25 · 10−3 and 15.7 · 10−3 L mol−1 s−1. The glass transition temperature of the polymer, 191°C, was measured by the Alternating Differential Scanning Calorimetry (ADSC) technique. Computed conversions from the developed kinetic model were in good agreement with the conversion and molecular weight measured data. The values of diffusion controlled propagation and termination rate constants ktd0 and kpd0 with clear and physical meaning were the only two parameters obtained from the developed kinetic model fitting. Polym. Eng. Sci. 44:2005–2018, 2004. © 2004 Society of Plastics Engineers.
Facile synthesis and crosslinking reaction of trifunctional five‐membered cyclic carbonate and dithiocarbonate
Authors: Suzuki Akane , Nagai Daisuke , Ochiai Bungo , Endo Takeshi
Published: October 2004

The trifunctional five‐membered cyclic carbonate 2 and dithiocarbonate 3 were successfully synthesized by the reaction of trifunctional epoxide 1 with carbon dioxide and carbon disulfide, respectively. The crosslinking reactions of 2 with p‐xylylenediamine or hexamethylenediamine were carried out in dimethyl sulfoxide at 100 °C for 48 h to produce the corresponding crosslinked poly(hydroxyurethane)s quantitatively. The crosslinking reactions of 3 with both p‐xylylenediamine and hexamethylenediamine, followed by acetylation of thiol moiety, produced the corresponding crosslinked poly(thioester–thiourethane)s quantitatively. The obtained crosslinked poly(hydroxyurethane)s were thermally more stable than the analogous crosslinked poly(thioester–thiourethane)s, probably because of less thermal stability of thiourethane moiety than hydroxyurethane moiety. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5983–5989, 2004
Novel positive‐working and aqueous‐base‐developable photosensitive poly(imide benzoxazole) precursor
Authors: Lien‐Chung Hsu Steve , Chen Hui‐Tzu , Tsai Shih‐Jung
Published: October 2004

A novel positive‐working and aqueous‐base‐developable photosensitive poly(imide benzoxazole) precursor based on a poly(amic acid hydroxyamide) bearing phenolic hydroxyl groups and carboxylic acid groups, a diazonaphthoquinone (DNQ) photosensitive compound, and a solvent was developed. Poly(amic acid hydroxyamide) was prepared through the polymerization of 2,2‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane, trimellitic anhydride chloride, and 4,4′‐oxydibenzoyl chloride. Subsequently, the thermal cyclization of the poly(amic acid hydroxyamide) precursor at 350 °C produced the corresponding poly(imide benzoxazole). The inherent viscosity of the precursor polymer was 0.17 dL/g. The cyclized poly(imide benzoxazole) showed a high glass‐transition temperature of 372 °C and 5% weight loss temperatures of 535 °C in nitrogen and 509 °C in air. The structures of the precursor polymer and the fully cyclized polymer were characterized with Fourier transform infrared and 1H NMR. The photosensitive polyimide precursor containing 25 wt % DNQ photoactive compound showed a sensitivity of 256 mJ/cm2 and a contrast of 1.14 in a 3‐μm film with a 0.6 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 5 μm was obtained from this composition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5990–5998, 2004
Vereinfachter Nachweis für I‐ und U‐Träger – beansprucht durch doppelte Biegung und Torsion
Authors: Lindner Joachim , Glitsch Torsten
Published: October 2004

Vereinfachte Nachweise für Bauteile in Form von Interaktionsgleichungen sind nach wie vor beliebt. Die in DIN 18800‐2 und EN 1993‐1‐1 vorgesehenen, die auch die plastischen Reserven von Querschnitten ausnutzen, schließen den Fall der planmäßigen Torsion bisher aus. Die Frage der Erfassung der planmäßigen Torsion wurde in einem Forschungsvorhaben behandelt, das an der RWTH Aachen, der RU Bochum und der TU Berlin durchgeführt wurde. Dabei wurden insgesamt 71 Großversuche und zusätzliche FEM‐Berechnungen durchgeführt, die es als “rechnerische” Versuche erlauben, das untersuchte Parameterfeld stark zu vergrößern. Hier wird über die an der TU Berlin durchgeführten Versuche berichtet, die Vergleichsrechnungen werden beschrieben, und die Ableitung einer Interaktionsgleichung mit den zugehörigen Interaktionsfaktoren wird erläutert. Die Anwendung wird durch Beispiele gezeigt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hangars für Flugzeuge
Authors: Müller‐Donges Rainer , Steinmann Ralf
Published: October 2004

Der folgende Artikel spannt den Bogen vom Nutzungskonzept über die erforderlichen Tragelemente bis zu den vielfältigen Gestaltungsmöglichkeiten eines individuellen Hangars und erläutert dies anhand von Beispielen.

“Die Stärke einer guten Tragstruktur ist das Resultat einfacher Gedankengänge, wobei ‘einfach’ nicht ‘primitiv’ heißt.” [Schulitz – 1989]
Wiederaufbau der Sloboda‐Brücke Novi Sad
Authors: Emge Alfons , Minas Frank
Published: October 2004

Die Sloboda Brücke in Novi Sad war zum Zeitpunkt der Planung eine der weltweit größten Schrägseilbrücken mit einer freien Spannweite von 351 m zwischen den Pylonen und einer Seilebene.

Anfang April 1999 wurde sie bei einem NATO‐Luftangriff von zwei Thomahawks jeweils am Pylonfußpunkt getroffen und dabei teilweise zerstört. Da die zerstörte Brücke eine der größten internationalen Wasserstraßen Europas gesperrt hat, bestand die dringende Notwendigkeit, die Brücke aus der Donau zu räumen und wieder aufzubauen, um den ungehinderten Schiffsverkehr zu ermöglichen.
Vom Stahlbauer zum Generalunternehmer
Authors: Goldbeck Ortwin
Published: October 2004

Diese Überschrift macht bereits den Wandel deutlich, der mit einer ungeheuren Dynamik alle Firmen, alle Branchen, ja die ganze Wirtschaft herausfordert. Und auch unsere Branche, die Baubranche, oder noch enger gesehen, der Stahlbau, muß nicht nur mit konjunkturellen Anpassungen, sondern auch mit grundsätzlichen strukturellen Veränderungen fertig werden.

Es soll weder eine volkswirtschaftliche, wissenschaftliche Analyse zur Bewältigung des Strukturwandels gegeben werden noch ein Maßnahmenkatalog eines Unternehmensberaters formuliert werden, sondern Gedanken und Überlegungen vorgestellt werden, die ein mittelständischer Unternehmer anstellt, um das eigene Unternehmen zukunftsfähig zu machen.
Reaktionen von Nitrilen mit tBuAsLi2
Authors: Iravani Effat , Neumüller Bernhard
Published: October 2004

Mit α‐aciden Nitrilen wie dem Malonsäuredinitril reagiert tBuAsLi2in THF/TMEDA unter Deprotonierung und Bildung des Koordinationspolymeren [{Li(TMEDA}{HC(CN)2}]n (1). Mit dem dazu relativ basenstabilen PhCN erfolgt unter Aromatisierung der Aufbau eines Diazaarsolids, koordiniert im Salz [Li(Diglyme)2][Li(TMEDA){As[NC(Ph)NC(Ph)]}2] (2). 1 und 2 wurden mittels NMR‐ und Schwingungsspektroskopie, Massenspektrometrie sowie Röntgenstrukturanalysen charakterisiert. Danach liegen im Festkörper von 1 unendliche helicale Ketten von Kationen und Anionen vor, die sich entlang [010] erstrecken. 2 besteht aus einem verzerrt oktaedrisch koordinierten Li+‐Ion, dem [Li(Diglyme)2]+, und dem komplexen Anion [Li(TMEDA){As[NC(Ph)NC(Ph)]}2]‐ mit einer verzerrt tetraedrischen Koordinationssphäre des Li+‐Ions.
Four New Thioantimonates(III) with the General Formula [TM(tren)]Sb4S7 (TM = Mn, Fe, Co, Zn) with the Transition Metal as Part of a Thioantimonate(III) Network Synthesized under Solvothermal Conditions and Tuning of the Optical Band Gap by the Transition Metal Cation
Authors: Schaefer Michael , Stähler Ralph , Kiebach Wolff‐Ragnar , Näther Christian , Bensch Wolfgang
Published: October 2004

Four new thioantimonate(III) compounds with the general formula [TM(tren)]Sb4S7, TM = Mn 1, Fe 2, Co 3 and Zn 4, were synthesized under solvothermal conditions by reacting elemental TM, Sb and S in an aqueous solution of tren (tren = tris(2‐aminoethyl)amine). All compounds crystallize in the monoclinic space group P21/n with four formula units in the unit cell. Single crystal X‐ray analyses of 1 [a = 8.008(2), b = 10.626(2), c = 25.991(5) Å, β = 90.71(3)°, V = 2211.4(8) Å3], 2 [a = 8.0030(2), b = 10.5619(2), c = 25.955(5) Å, β = 90.809(3)°, V = 2193.69(8) Å3], 3 [a = 7.962(2), b = 10.541(2), c = 25.897(5) Å, β = 90.90(3)°, V = 2173.0(8) Å3] and 4 [a = 7.978(2), b = 10.625(2), c = 25.901(5) Å, β = 90.75(3)°, V = 2195.2(8) Å3] reveal that the compounds are isostructural. The [Sb4S7]2‐ anions are composed of three SbS3 trigonal pyramids and one SbS4 unit as primary building units (PBU). The PBUs share common edges and corners to form semicubes (Sb3S4) which may be regarded as secondary building units (SBU). The SBUs and SbS3 pyramids are joined in an alternating fashion yielding the [Sb4S7‐] anionic chain which is directed along [100]. Weaker Sb‐S bonding interactions between neighbored chains lead to the formation of layers within the (001) plane which contain pockets that are occupied by the cations. The TM2+ ions are in a trigonal bipyramidal environment of four N atoms of the tren ligand and one S atom of the thioantimonate(III) anion. The optical band gaps depend on the TM2+ ion and amount to 3.11 eV for 1, 2.04 eV for 2, 2.45 eV for 3, and 2.60 eV for 4.
Gas Phase Catalysis by Metal Nanoparticles in Nanoporous Alumina Membranes
Authors: Kormann Hans‐Peter , Schmid Günter , Pelzer Katrin , Philippot K. , Chaudret Bruno
Published: October 2004

Nanoporous alumina membranes, loaded with palladium and ruthenium nanoparticles of various size, were used for gas phase hydrogenation of 1, 3‐butadiene and for oxidation of carbon monoxide, respectively. Those membranes contain 109 ‐ 1011 pores per cm2, all running perpendicular to the surface. Membrane discs of 20 mm in diameter and only 60 μm thick, incorporated in a reactor in which the reactants can be pumped in a closed circuit through the pores, turned out to very actively catalyze hydrogenation of butadiene (Pd) and oxidation of CO (Ru). The activity of the Pd catalysts depends characteristically on the particles size, the gas flow, and of the educts ratio. As could be expected, larger particles are less active than smaller ones, whereas increasing gas flows in case of hydrogenation accelerates the reactions. Excessive hydrogen reduces selectivity with respect to the various butenes, but favours formation of butane.
[(Mes3Sn)2MoO4], ein monomeres Triorganozinnmolybdat
Authors: Kondracka Małgorzata , Herntrich Tobias , Merzweiler Kurt
Published: October 2004

[(Mes3Sn)2MoO4], a Monomeric Triorganotin Molybdate

Mes3SnBr (Mes = 1, 3, 5‐trimethylphenyl) reacts with (NBu4)2[Mo6O19] in the presence of (NBu4)OH (in CH3CN as solvent) to form [(Mes3Sn)2MoO4]. Alternatively the title compound can be obtained from the reaction of [MoO2(acac)2] (acac = 2, 4‐pentadionate) with Mes3SnOH in isopropanol. [(Mes3Sn)2MoO4] forms monoclinic crystals, space group C2/c, with a = 2271.6(3) pm, b = 825.2(1) pm, c = 2739.9(5) pm, β = 90.96(2)°. The crystal structure consists of isolated molecules in which a tetrahedral MoO4 unit is connected to two terminal Mes3Sn groups. The Mo‐O distances range from 169.6(4) to 181.1(3) pm and the Sn‐O distance is 204.8(3) pm.
Synthesis and Molecular Structures of Platinum and Mercury Complexes Chelated by (Phenylthiomethyl)silane Ligands
Authors: Knorr Michael , Peindy Harmel N. , Guyon Fabrice , Sachdev Hermann , Strohmann Carsten
Published: October 2004

Metathesis reaction of the dithioether complex cis‐[PtCl2{(PhSCH2)2SiPh2}] (2a) with NaBr and NaI yields the square planar complexes cis‐[PtX2{(PhSCH2)2SiPh2}] (2b, X = Br; 2c, X = I). The new compounds, which are fluxional in solution, have been studied by multinuclear NMR techniques; the crystal structures of 2a‐c have been determined by X ray diffraction. This series allows to evaluate the trans‐influence of the halide ligands on the lengths of the Pt‐S bonds, which increase from 227.26(12) (2a), 228.46(13) (2b) to 229.96(15) (2c) pm due to a more pronounced trans‐influence of I compared with Br and Cl. Complexation of (PhSCH2)2SiPh2 (1a) on HgBr2 gives the distorted tetrahedral compound [HgBr2{(PhSCH2)2SiPh2}] (3), having a quite loose coordination of the ligand both in solution and in the solid state [Hg‐S = 291.88(2) pm]. Alternatively, the coordination around Hg may be described as distorted square pyramidal in the solid state, since to due to a weak intermolecular Hg···Br interaction [346.72(13) pm], a dimeric motif is formed. Furthermore, the functionalised cyclic silane (PhSCH2)2SiC4H6 (1b) has been prepared and co‐ordinated as chelating dithioether ligands to [PtCl2(PhCN)2] affording the dithioether complex cis‐[PtCl2{(PhSCH2)2SiC4H6)}] (4). The crystal structure of 4 has also been determined by an X‐ray diffraction study.
Structural Variances in the Homologous Series of Alkaline Earth Metallated Octamethylcyclotetrasilazandiides
Authors: Lameyer Lutz , Salah Omar Abu , Deuerlein Stephan , Stey Thomas , Stalke Dietmar
Published: October 2004

The magnesium, calcium, and strontium metal derivatives of 2, 2, 4, 4, 6, 6, 8, 8‐octamethylcyclotetrasilazane (OMCTS) have been synthesized and structurally characterized by X‐ray diffraction studies. These are the first complexes of the homologous series of alkaline earth metalated OMCTS. Similar to the homologous series of the corresponding alkali metal complexes, the structural properties show remarkable tendencies in the series from magnesium to strontium. The magnesium dication causes the most pronounced deformation along the transannular N‐···N‐ vector of the [(c‐N‐SiMe2‐NH‐SiMe2‐)2]2‐ dianionic ring. The lengths of the Si‐N bonds are correlated to the bond types, so that shorter distances result when the bonds become more ionic. The difference between the long Si‐N(H) bonds and the short Si‐N‐ bonds decreases gradually with the increasing mass of the alkaline earth metal dication.
Mitogen‐activated protein kinase phosphatase‐1 (MKP‐1): >100‐fold nocturnal and norepinephrine‐induced changes in the rat pineal gland
Authors: Price Donald M. , Chik Constance L. , Terriff David , Weller Joan , Humphries Ann , Carter David A. , Klein David C. , Ho Anthony K.
Published: October 2004

The norepinephrine‐driven increase in mitogen‐activated protein kinase (MAPK) activity is part of the mechanism that regulates arylalkylamine N‐acetyltransferase (AA‐NAT) activity in the rat pineal gland. We now report a marked nocturnal increase in the expression of a MAPK phosphatase, MAP kinase phosphatase‐1 (MKP‐1), that was blocked by maintaining animals in constant light or treatment with propranolol. MKP‐1 expression was regulated by norepinephrine acting through both α‐ and β‐adrenergic receptors. These results establish a nocturnal increase in pineal MKP‐1 expression that is under the control of a photoneural system. Because substrates of MKP‐1 can influence AA‐NAT activity, our findings suggest the involvement of MKP‐1 in the regulation of the nocturnal AA‐NAT signal.
Regulating cell survival by controlling cellular energy production: novel functions for ancient signaling pathways?
Authors: Kuznetsov Andrey V. , Janakiraman Manickam , Margreiter Raimund , Troppmair Jakob
Published: October 2004

Cell survival is maintained by growth factors and critically depends on sufficient energy supply. New evidence suggests that a rise in cellular energy production is not merely a homeostatic response to increased demand but subject to regulation by extrinsic factors. The mechanisms operating in this control are largely enigmatic. Work on transformed cells identified direct targeting of glycolytic enzymes by signaling proteins as one possibility. But mitochondrial oxidative phosphorylation and biogenesis may also be subject to regulation by growth and survival factors. Both, positive and negative regulators of cell survival impinge on the processes of cellular energy production to regulate growth and survival versus death.
Observations of natural behaviour of yellowtail flounder derived from data storage tags
Authors: Walsh Stephen J. , Morgan M. Joanne
Published: October 2004

Electronic data storage tags (DSTs) were used to monitor natural behaviour of adult yellowtail flounder (Limanda ferruginea) in relation to depth, temperature, time of day, and season. Over a 2-year period, a total of 543 fish tagged with DSTs were released during June of each year. Results from 29 tags revealed that yellowtail flounder exhibit diel and seasonal variations in depth and temperature. The results also show, for the first time in this species, that during various times of the year yellowtail flounder make extensive off-bottom movements at night and can remain off bottom for several hours.
Mathematical model of fish schooling behaviour in a set-net
Authors: Takagi Tsutomu , Moritomi Yutaka , Iwata Jyun , Nakamine Hiroshi , Sannomiya Nobuo
Published: October 2004

We investigated the validity of a mathematical model to describe fish schooling behaviour towards a simple set-net model. We apply a model considered to be “an autonomous decentralized system” and based on Newton's equation of motion. It includes the parameter M, which indicates “the quantity of information exchange” (i.e. the number of neighbours that affect an individual's behaviour) and strongly affects fish school size and schooling behaviour in an enclosed space. To evaluate the model, simulations of fish schooling behaviour in a set-net model consisting of a leading fence and a box-shaped trap similar to a primitive type of set-net were compared with experimentally observed behaviour of bitterling and mackerel, with a focus on M. A small M induces improper behaviour because there is low cooperation among fish in a school. On the other hand, if M is too large, improper simulation results of individuals in deadlock states in the trap are obtained as a result of excessive information exchange among the fish. The results suggest that the mathematical model can describe the behaviour in a set-net model adequately when M is greater than 2 and less than 10.
Clinical correlates and symptom patterns of anxious depression among patients with major depressive disorder in STAR*D
Authors: FAVA MAURIZIO , ALPERT JONATHAN E. , CARMIN CHERYL N. , WISNIEWSKI STEPHEN R. , TRIVEDI MADHUKAR H. , BIGGS MELANIE M. , SHORES-WILSON KATHY , MORGAN DON , SCHWARTZ TERRY , BALASUBRAMANI G. K. , JOHN RUSH A.
Published: October 2004

Background. Anxious depression, defined as Major Depressive Disorder (MDD) with high levels of anxiety symptoms, may represent a relatively common depressive subtype, with distinctive features.

Objective. The objective of this study was to determine the prevalence of anxious depression and to define its clinical correlates and symptom patterns.

Method. Baseline clinical and sociodemographic data were collected on 1450 subjects participating in the STAR*D study. A baseline Hamilton Rating Scale for Depression (HAM-D) Anxiety/Somatization factor score of [ges ]7 was considered indicative of anxious depression. The types and degree of concurrent psychiatric symptoms were measured using the Psychiatric Diagnostic Screening Questionnaire (PDSQ), by recording the number of items endorsed by study participants for each diagnostic category. MDD symptoms were assessed by clinical telephone interview with the 30-item Inventory of Depressive Symptomatology (IDS-C30).

Results. The prevalence of anxious depression in this population was 46%. Patients with anxious MDD were significantly more likely to be older, unemployed, less educated, more severely depressed, and to have suicidal ideation before and after adjustment for severity of depression. As far as concurrent psychiatric symptoms are concerned, patients with anxious depression were significantly more likely to endorse symptoms related to generalized anxiety, obsessive compulsive, panic, post-traumatic stress, agoraphobia, hypochondriasis, and somatoform disorders before and after adjustment for severity of depression. Anxious-depression individuals were also significantly less likely to endorse IDS-C30 items concerning atypical features, and were significantly more likely to endorse items concerning melancholic/endogenous depression features.

Conclusion. This study supports specific clinical and sociodemographic correlates of MDD associated with high levels of anxiety (anxious depression).
Familial influence on offspring gambling: a cognitive mechanism for transmission of gambling behavior in families
Authors: OEI TIAN P. S. , RAYLU NAMRATA
Published: October 2004

Background. The problem-gambling literature has identified a range of individual, cognitive, behavioral and emotional factors as playing important roles in the development, maintenance and treatment of problem gambling. However, familial factors have often been neglected. The current study aims to investigate the possible influence of parental factors on offspring gambling behavior.

Method. A total of 189 families (546 individuals) completed several questionnaires including the South Oaks Gambling Screen (SOGS) and the Gambling Related Cognition Scale (GRCS). The relationships were examined using Pearson product-moment correlations and structural equation modeling (SEM) analyses.

Results. Results showed that generally parents' (especially fathers') gambling cognitions and gambling behaviors positively correlated with offspring gambling behaviors and cognitions. However, SEM analyses showed that although parental gambling behavior was directly related to offspring gambling behavior, parental cognitions were not related to offspring gambling behavior directly but indirectly via offspring cognitions.

Conclusion. The findings show that the influence of parental gambling cognition on offspring gambling behavior is indirect and via offspring cognitions. The results suggest a possible cognitive mechanism of transmission of gambling behavior in the family from one generation to the next.
Defining the cognitive impairment in schizophrenia
Authors: JOYCE EILEEN , HUDDY VYV
Published: October 2004

Cognitive psychology became an important discipline in schizophrenia research when information processing deficits were implicated as the basis from which psychotic symptoms emerged (Broen & Storms, 1967; Hemsley, 1977; Frith, 1979). The study of cognition as an independent construct began in earnest when the detection of brain morphological abnormalities on computed tomography (CT) in patients with schizophrenia (Johnstone et al. 1976; Weinberger et al. 1979) prompted the search for behavioural correlates. It became apparent that impairments typical of damage to frontal or medial temporal lobes could be seen in patients with schizophrenia, irrespective of symptom type or severity (Goldberg et al. 1988; McKenna et al. 1990). Since then a number of findings have been replicated sufficiently to make certain conclusions about the nature and extent of cognitive dysfunction in this disorder.
The catechetical function of Reformed hymnody
Authors: Sherman Robert
Published: October 2004

Has Reformed hymnody played a catechetical role in propagating characteristically Reformed theological emphases? While early Reformed ‘hymnody’ focused on the Psalms, the eighteenth century saw a great proliferation of Reformed hymns employing non-scriptural language. For example, the hymnody of English Congregationalist Isaac Watts shows both the traditional use of psalms and the innovative creation of hymns of praise, thanksgiving and theological narration. This paper considers how Reformed hymnody has served that tradition's catechetical purposes, taking as a test case the ways in which its hymnody may have helped inculcate the characteristically Reformed emphasis on the threefold office of Christ.
Oceanic ventilation and biogeochemical cycling: Understanding the physical mechanisms that produce realistic distributions of tracers and productivity
Authors: Gnanadesikan Anand , Dunne John P. , Key Robert M. , Matsumoto Katsumi , Sarmiento Jorge L. , Slater Richard D. , Swathi P. S.
Published: October 2004

Differing models of the ocean circulation support different rates of ventilation, which in turn produce different distributions of radiocarbon, oxygen, and export production. We examine these fields within a suite of general circulation models run to examine the sensitivity of the circulation to the parameterization of subgridscale mixing and surface forcing. We find that different models can explain relatively high fractions of the spatial variance in some fields such as radiocarbon, and that newer estimates of the rate of biological cycling are in better agreement with the models than previously published estimates. We consider how different models achieve such agreement and show that they can accomplish this in different ways. For example, models with high vertical diffusion move young surface waters into the Southern Ocean, while models with high winds move more young North Atlantic water into this region. The dependence on parameter values is not simple. Changes in the vertical diffusion coefficient, for example, can produce major changes in advective fluxes. In the coarse‐resolution models studied here, lateral diffusion plays a major role in the tracer budget of the deep ocean, a somewhat worrisome fact as it is poorly constrained both observationally and theoretically.
African dry air outbreaks
Authors: Zhang Chidong , Pennington Jeremy
Published: October 2004

Dry air outbreaks from Africa into the tropical Atlantic region are documented using daily layered precipitable water (LPW) data of satellite remote sensing for 1993–1997. A dry air outbreak is defined as an abrupt decrease in middle‐troposphere (700–500 hPa) LPW that is greater than 1 mm d−1 and remains below normal for at least two consecutive days in a reference box off the west coast of Africa. Pathways of individual dry air outbreaks thus identified are tracked both forward and backward in time. Dry air outbreaks intruding into the tropical Atlantic may originate from different source regions: the northern Atlantic Ocean, northern Africa, Sahel, and equatorial Africa. Some of these outbreaks can keep their identities up to 2 weeks, propagate across the Atlantic Ocean, and reach South America and the Caribbean Sea. Boreal summer is the overall peak season, with the majority of the outbreaks occurring north of the Intertropical Convergence Zone (ITCZ). In spring more outbreaks occur south of the ITCZ. Precipitation in the ITCZ tends to decrease during periods of the outbreaks in both spring and summer. Observed large‐scale patterns of African dry air outbreaks are compared to known characteristics of African dust outbreaks. The results from this study suggest that African dry air outbreaks should and can be treated as prominent phenomena independent of African dust outbreaks. This study calls for systematic investigations on the similarities and differences between African dust and dry air outbreaks for a better understanding of their effects on weather and climate in the tropical Atlantic region.
Seismic evidence for a water‐filled canal in deforming till beneath Rutford Ice Stream, West Antarctica
Authors: King Edward C. , Woodward John , Smith Andrew M.
Published: October 2004

Seismic data from Rutford Ice Stream, West Antarctica show high amplitude, reversed‐polarity reflections from parts of the bed. Only interfaces between ice and water, or between water and sediment have the acoustic properties to produce such strong reflections – ice/sediment interfaces produce much weaker echoes. The evidence suggests that an area of the ice stream measuring at least 1 km by 0.2 km is underlain by water with a depth of less than 1 m. The data are consistent with the presence of a sub‐ice drainage system comprising shallow canals cut into the sedimentary substrate, as predicted by theory.
Diurnal variations of surface ocean pCO2 and sea‐air CO2 flux evaluated using remotely sensed data
Authors: Olsen Are , Omar Abdirahman M. , Stuart‐Menteth Alice C. , Triñanes Joaquin A.
Published: October 2004

This paper evaluates the effect of diurnal variations of sea surface temperature (SST) and wind speed on the surface ocean CO2 partial pressure (pCO2sw) and sea‐air CO2 flux. This is carried out using a combination of climatological and remote sensing data. The calculations show that the diurnal heating cycle can drive a diurnal pCO2sw variability which may cause the global ocean uptake of CO2 to be more than twice as large during night than during day. The effect of diurnal wind speed variations on the sea‐air CO2 flux is restricted to the tropics. The concurrent variations of SST and wind speed on diurnal time scales bring around covariance terms that may contribute to the monthly mean flux. These were estimated and found to be negligible. Thus, this study validates the use of diurnally averaged fields for computation of sea‐air CO2 fluxes.
What drives heat transport in the Atlantic: Sensitivity to mechanical energy supply and buoyancy forcing in the Southern Ocean
Authors: Saenko Oleg A. , Weaver Andrew J.
Published: October 2004

Climate model simulations are used to demonstrate that there is not a simple link between the mechanical energy supply and heat transport in the Atlantic. Setting the flux of momentum into the ocean to zero between 35–60°S reduces the net mechanical energy input by more than a factor of two without much effect on the heat transport in the Atlantic. The strong westerly winds in the Southern Ocean are found to be more important for the circulation of bottom water and for localizing the upwelling of deep water around Antarctica. Furthermore, it is illustrated that the hydrological cycle plays a significant role in maintaining the global ocean circulation and the associated heat transport in the Atlantic, given sufficient mechanical energy to support the diapycnal mixing. A reduction of the meridional moisture transport to the Southern Ocean by a factor of two reduces heat transport in the Atlantic by about the same factor.
Ground‐based detection of TLE‐producing intense lightning during the MEIDEX mission on board the space shuttle Columbia
Authors: Price C. , Greenberg E. , Yair Y. , Sátori G. , Bór J. , Fukunishi H. , Sato M. , Israelevich P. , Moalem M. , Devir A. , Levin Z. , Joseph J. H. , Mayo I. , Ziv B. , Sternlieb A.
Published: October 2004

In January 2003 Transient Luminous Events (TLEs) also known as sprites and ELVES were observed by the astronauts on board of the Columbia space shuttle, during the Mediterranean Israeli Dust Experiment (MEIDEX). Throughout the 16‐day mission, electromagnetic data at four ground‐based Extremely Low Frequency (ELF) stations (Israel, Hungary, Japan and Antarctica) were collected to geo‐locate and determine the parameters of the parent lightning that triggered the TLEs. From our analysis 7 ELVES and 7 sprites have been detected so far in our data. ELF transients were detected for 5 of 7 ELVES at all ground stations with accurate geo‐location of these events. However, none of the sprites were associated with ELF transients. This is contrary to the present theories of TLE formation, and may require some new thinking into the mechanisms that produce sprites and ELVES.
Denmark Strait overflow: Comparing model results and hydraulic transport estimates
Authors: Kösters F.
Published: October 2004

The transport of dense water through Denmark Strait is investigated with a high‐resolution numerical model. The results are compared with different transport estimates from rotating hydraulic theory in order to evaluate such theories with respect to the interpretation of hydrographic data. Generally, estimates far upstream result in upper transport limitations that can be appropriately scaled to give time mean transport estimates, whereas estimates from the sill entrance region can provide a good approximation of the variable transport.