bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetric reduction and Meerwein‐Ponndorf‐Verley reaction of prochiral aromatic ketones in the presence of optically pure 1‐aryl‐2,2‐dimethylpropane‐1,3‐diols
Authors: Xianming Hu , Kellogg Richard M.
Published: September 2010

In THF solution, NaBH4 in the presence of (S)‐(‐)‐1‐(2‐chlorophenyl)‐2,2‐dimethylpropane‐1,3‐diol together with 2‐chlorobenzoic acid reduced propiophenone to 1‐ phenylpropan‐1‐ol in up to 40% enantiomeric excess (ee). Only 21% ee was obtained without an added acid. (R)‐(‐)‐butane‐1,3‐diol and (R)‐( + )‐1,1′‐binaphthalene‐2,2′‐diol did not form clear solutions with NaBH4 in THF and only gave a low ee. Of the organic acid additives investigated, (S)‐(–)‐4‐(2‐chlorophenyl)‐5,5‐dimethyl‐2‐hydroxy‐1,3,2‐dioxaphosphorinane 2‐oxide gave the highest ee (46%). However, with AlCl3/NaBH4/(S)‐(–)‐1‐(2‐chlorophenyl)‐2,2‐dimethylpropane‐1,3‐diol in THF the best result was obtained (ee 55%).

Asymmetric Meerwein‐Ponndorf‐Verley (MPV) reductions of acetophenone by isopropanol in the presence of these chiral diols as auxiliary have also been carried out. For the case of aluminium triisopropoxide, (R)‐(–)‐1‐phenyl‐2,2‐dimethylpropane‐1,3‐diol and acetophenone(1/1/1), an ee of up to 20% for 1‐phenylethanol was obtained whereas with (R)‐(+)‐1,1′‐binaphthalene‐2,2′‐diol an ee of 32% was obtained. Lanthanide triisopropoxides, Ln(OiPr)3, have also been used. Of the various lanthanides (Ln = La, Y, Er, Tb, and Eu) the Er triisopropoxide with chiral (R)‐(–)‐1‐phenyl‐2,2‐dimethyl‐propane‐1,3‐diol gave the best result; 46% ee for 1‐phenylethanol. Lanthanide chloride diisopropoxides, LnCl(OiPr)2, were also used as catalysts; although these have high catalytic activities they unfortunately give little chiral recognition.
Polyanion inhibitors of human immunodeficiency virus. Part III. Polymerized anionic surfactants derived from D‐glucose
Authors: Leydet Alain , Jeantet‐Segonds Christine , Barthélémy Philippe , Boyer Bernard , Roque Jean Pierre
Published: September 2010

A series of new polyanions was synthesized via γ‐polymerization in aqueous micellar solution of ω‐unsaturated anionic surfactants derived from D‐glucose. These polyanions were evaluated for their activity against HIV‐1. All tested compounds proved active, although non‐toxic to the host cells (CEM‐4).
A new and convenient method for the preparation of 2,7‐dihydro‐1H‐dibenzo[c,e]tellurepin: Reactions and ligand properties
Authors: Al‐Rubaie Ali Z. , Al‐Marzook Asmahan Y. , Al‐Jadaan Shakeer A. N.
Published: September 2010

Treatment of 2,2′‐bis(bromomethyl)biphenyl with potassium tellurocyanate in dry DMSO gave 1,7‐dihydro‐1H‐dibenzo[c,e]tellurepin (1) in 60% yield as an unexpected product. The following new derivatives of 1 have been prepared: C14H12TeCl2 (2), C14H12TeBr2 (3), C14H12Tel2 (4), C14H12Te(CH3)I (5) and C14H12Te(C2H5)I (6).

Mononuclear and dinuclear palladium complexes [i.e. (C14H12)2PdCl2 (7) and [(C14H12Te)PdCl2]2 (8)] were prepared by the reaction of 1 with PdCl2(PhCN)2 and Na2PdCl4, respectively. Reaction of RhCl3 · 3H2O with an excess of 1 gave the monomeric Rh(I) complex, (C14H12Te)3RhCl (9). Compound 1 readily forms a 1: 1 charge‐transfer complex with TCNE while it reduces the carbonyl groups in DDQ and TCQ to hydroxyl groups. Conductivity, UV‐Vis, IR and 1H‐ and 13C‐NMR data for the new compounds are presented and discussed.
First stereospecific synthesis of (E)‐1,2‐bis(selenocyanato)ethenes by the addition of dicyanodiselenide to acetylenes
Authors: Potapov V.A. , Amosova S.V. , Dudareva G.N. , Shestakova V.Y.U. , Zhnikin A.R. , Petrov B.V. , Aksamentova T.N.
Published: September 2010

The addition of dicyanodiselenide to acetylene, phenylacetylene and diphenylacetylene proceeds in an anti manner to afford, in 70‐80% yield, (E)‐1,2‐bis(selenocyanato)ethenes which are prospective precursors of polymers with potential conductivity.
The study of NO adsorbate layers on platinized platinum in the liquid phase with cyclic voltammetry, DEMS and FTIRS
Authors: Gootzen J.F.E. , van Hardeveld R.M. , Visscher W. , van Santen R.A. , van Veen J.A.R.
Published: September 2010

The irreversible adsorbates formed after exposure of platinum to an NO‐containing solution were studied with Differential Electrochemical Mass Spectrometry (DEMS), Fourier‐Transform Infrared Spectroscopy (FTIRS) and cyclic voltammetry. DEMS and FTIRS show that only a very small amount of N2O is formed in the reduction of the adsorbate, indicating that mainly non‐volatile products are formed. FTIRS shows, in addition, vibrations of NO at wavenumbers characteristic of adsorbed NO on Pt(100) and Pt(110) sites. These two different adsorption sites are characterized by separate reduction peaks in the cyclic voltammogram. Further, it was established with FTIRS that the adsorbate is transformed to N2O and NH+4 in the reduction, and to NO−3 in the oxidation. Analysis of the charges involved in the reduction and oxidation of the irreversible adsorbates demonstrates that coadsorbates are present next to NO. The coadsorbates consist of adsorbed nitrogen atoms, formed by the dissociation of NO. This view is supported by previously reported studies in Ultra High Vacuum (UHV). A new mechanism for the reduction of NO to N2O in the liquid phase is proposed on the basis of NO dissociation.
Phosphoramidites: Novel modifying ligands in rhodium catalysed hydroformylation
Authors: van Rooy Annemiek , Burgers Dennis , Kamer Paul C. J. , van Leeuwen Piet W. N. M.
Published: September 2010

The phosphoramidites 2–9 have been applied as modifying ligands in rhodium‐catalysed hydroformylation of oct‐1‐ene and styrene. Monodentate phosphoramidites 2–5 gave rise to catalysts with average rates of 1000 mol [mol Rh]−1 h−1 and maximum selectivities of 65% to the linear product nonanal for the hydroformylation of oct‐1‐ene (P 20 bar CO/H2, T 80°C, [oct‐1‐ene] ≈︁ 1 M). Styrene was hydroformylated (T 40°C, P 20 bar CO/H2) at rates up to 150 mol [mol Rh]−1 h−1 and a selectivity for the branched 2‐phenylpropanal of 93%. Using diphosphoramidite modified catalysts a maximum rate of 1200 mol.[mol Rh]−1.h−1 for oct‐1‐ene was observed for 9, with 91% regioselectivity for the linear product. At 40°C styrene was hydroformylated at rates up to 25 mol [mol Rh]−1 h−1 and with selectivities for the branched aldehyde of 89%. Characterization of the rhodium complexes showed that formation of rhodium hydride complexes is slow and incomplete under the conditions applied for the monophosphoramidites. The diphosphoramidite ligands all form bidentate hydrido‐rhodium complexes. The diphosphoramidite ligands 6–9 coordinate bis‐equatorially in the trigonal bipyramidal rhodium complexes, which accounts for the high regioselectivities.
Biocatalytic large‐scale production of 13(S)‐hydroperoxy‐9(Z), 11(E) octadecadienoic acid from hydrolysed safflower oil by a crude soybean‐flour extract as lipoxygenase source
Authors: Elshof M.B.W. , Janssen M. , Veldink G.A. , Vliegenthart J.F.G.
Published: September 2010

Lipoxygenase‐1 extracted from crude soybean‐flour was incubated with hydrolysed safflower oil as a substrate in a 7‐1 fermentor. Optimized reaction conditions included pH 10.0, 5°C and air saturation. Under these conditions production on a 40‐g/l scale can easily be carried out yielding up to 80% 13‐hydroperoxy‐9(Z), 11 (E)‐octadecadienoic acid with a stereo‐configuration of essentially (>95%) S.
The reaction of ammonia and ethanol or related compounds towards pyridines over high‐silica zeolites with medium pore size
Authors: le Febre R.A. , Hoefnagel A.J. , van Bekkum H.
Published: September 2010

Pyridine bases were formed by the reaction of ethanol and ammonia over zeolite Nu‐10 in the presence of oxygen, which was shown to play an essential role. The use of different proton‐introduction procedures resulted in different activities and selectivities of the catalyst. H‐Nu‐10 and H‐ZSM‐5 showed substantially higher pyridine selectivity than H‐mordenite. In order to clarify the reaction mechanism of the title reaction, several other small amines and oxygenates were tested in the presence/absence of oxygen with respect to their selectivity towards pyridines. Zeolitic acid sites were shown to catalyse the dehydrogenation of ethanol, together with condensation, cyclization and aromatization, while structural defects probably produced oxidation products such as acetaldehyde and formaldehyde which are thought to play an important role in the reaction. The use of methylamine instead of ammonia greatly enhanced the pyridine selectivity.
The mechanism of n‐butane oxidation. Characterization of titania‐supported V‐P‐O catalysts by pulse‐flow experiments and in‐situ XANES spectroscopy
Authors: Ruitenbeek M. , Overbeek R.A. , van Dillen A.J. , Koningsberger D.C. , Geus J.W.
Published: September 2010

Well‐dispersed supported V‐P‐O (Vanadium Phosphorus Oxyde) catalysts were prepared and tested in the selective oxidation of n‐butane to maleic anhydride. Because of their high activity, it was possible to test titania‐supported catalysts in a two‐step oxidation reduction process at low temperatures. After n‐butane adsorption and activation in the absence of molecular oxygen, desorption took place after subsequent introduction of molecular oxygen into the gas stream, leading to the selective formation of maleic anhydride.

In‐situ XANES spectroscopy was performed under reaction conditions in the two‐step oxidation reduction process with a special titania‐supported V‐P‐O catalyst with a high loading. The results of these experiments showed that, after equilibration, no more changes in the valence state of vanadium were observed after reduction or subsequent re‐oxidation. This indicates that the generally assumed Mars‐Van‐Krevelen mechanism is not operative for the titania‐supported V‐P‐O catalyst.
Preparation, characterization and testing of titania‐supported iron oxide based dehydrogenation catalysts
Authors: Boot Ludo A. , van der Linde Simon C. , van Dillen Adrianus J. , Geus John W. , van Buren Frederik R.
Published: September 2010

Iron oxide‐based catalysts supported on titania and zirconia have been investigated as alternatives for the currently used bulk iron oxide dehydrogenation catalysts. The present study focuses on titania‐supported catalysts. Catalyst samples were prepared by pore‐volume impregnation of commercially available pre‐shaped support bodies with solutions of various iron precursor compounds. Transmission electron microscopy (TEM) and temperature‐programmed reduction (TPR) revealed that the best microscopic distribution is achieved with ammonium iron citrate. X‐ray diffraction (XRD) showed a difference between the investigated supports: on rutile TiO2, iron was present as hematite (Fe2O3), whereas on anatase, pseudobrookite (Fe2TiO5) was formed. When testing the catalytic activity in but‐1‐ene dehydrogenation, rapid deactivation was observed which could not be prevented by using a catalyst containing potassium. Without potassium, deactivation is attributed to the formation of ilmenite, FeTiO3. With potassium, the iron oxide phase reacts with both potassium and TiO2, which diminishes the activity which initially was present in catalysts without potassium. When a more inert support is used, viz. ZrO2, no solid state reaction is observed, and a stable catalyst is obtained.
Novel organomanganese(II) complexes active as homogeneous catalysts in manganese(II)/copper(I) catalyzed carbon‐carbon bond formation reactions
Authors: Donkervoort Johannes G. , Vicario José L. , Jastrzebski Johann T. B. H. , van Koten Gerard , Cahiez Gérard
Published: September 2010

Novel organomanganese complexes 3 and 4 were prepared via transmetallation of the corresponding organolithium reagent. These new complexes are active catalysts in manganese/copper mediated cross‐coupling reactions.
Hybrid Polymer‐Grafted Multiwalled Carbon Nanotubes for In vitro Gene Delivery
Authors: Nunes Antonio , Amsharov Nadja , Guo Chang , Van den Bossche Jeroen , Santhosh Padmanabhan , Karachalios Theodoros K. , Nitodas Stephanos F. , Burghard Marko , Kostarelos Kostas , Al‐Jamal Khuloud T.
Published: September 2010

Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymer‐grafted multiwalled carbon nanotubes (MWNTs) (polymer‐g‐MWNTs) to efficiently complex and transfer plasmid DNA (pCMV‐βGal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer‐g‐MWNTs as gene delivery systems, we first study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confirm pDNA binding to polymer‐g‐MWNT with different affinities, highest for PEI‐g‐MWNT and PEI/PAA‐g‐CNT constructs. β‐galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modified LDH assay after 24 h incubation period. Additionally, PEI‐g‐MWNT and/or PEI/PAA‐g‐MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymer‐g‐MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer‐g‐MWNTs may be considered in the future as a versatile tool for efficient gene transfer in cancer cells in vitro, provided their toxicological profile is established.
Testing aspect‐oriented programs with finite state machines
Authors: Xu Dianxiang , El‐Ariss Omar , Xu Weifeng , Wang Linzhang
Published: September 2010

Aspect‐oriented programming yields new types of programming faults due to the introduction of new constructs for dealing with crosscutting concerns. To reveal aspect faults, this paper presents a framework for testing whether or not aspect‐oriented programs conform to their state models. It supports two families of strategies (i.e. structure‐oriented and property‐oriented) for automated generation of aspect tests from aspect‐oriented state models. A structure‐oriented testing strategy derives tests and test code from an aspect‐oriented state model to meet a given structural coverage criterion, such as state coverage, transition coverage, or round trip. A property‐oriented testing strategy generates test code from the counterexamples of model checking. Two such strategies are checking an aspect‐oriented state model against trap properties and checking mutants of aspect models against system properties. Mutation analysis of aspect‐oriented programs is used to evaluate the effectiveness of these testing strategies. The experiments demonstrate that testing aspect‐oriented programs against their state models can detect many aspect faults. The comparative evaluations also reveal that the structure‐oriented and property‐oriented testing strategies complement each other—some aspect faults were detected by the structure‐oriented strategies, but not by the property‐oriented strategies and vice versa. Copyright © 2010 John Wiley & Sons, Ltd.
Mental time travel in animals
Authors: Cheke Lucy G. , Clayton Nicola S.
Published: September 2010

Twelve years on from Suddendorf and Corballis's mental time travel (MTT) hypothesis, the debate as to whether episodic cognition is unique to humans remains unresolved. In this article, we review the evidence for mental time travel in nonhuman animals and the empirical methods used in this field. Investigation of episodic‐like memory has been dominated by ‘What–Where–When’ paradigms, with limited success outside of food‐caching corvids, and with only scrub‐jays meeting Clayton and colleagues' more specific description of the underlying mnemonics. The recent emergence of an ‘unexpected question’ paradigm tapping recall of unattended aspects of episodes provides a promising new avenue for future studies. Falsification of the Bischof–Köhler hypothesis, that acting to satisfy a future motivational state is beyond the scope of nonhuman animals, has been the ‘holy grail’ of animal future planning research, spawning a plethora of studies. We argue that although the criterion proposed by this hypothesis provides a test for an explicit representation of a future time, it does nothing to get at whether planning for this future is mediated by semantic or episodic processes. WIREs Cogn Sci 2010 1 915–930

This article is categorized under:

Psychology > Memory
Übergangsmetall‐Komplexe mit π‐Allyl‐ und π‐Enyl‐Liganden
Authors: Fischer Ernst Otto , Werner Helmut
Published: September 2010

Komplexverbindungen mit π‐Allyl‐ bzw. π‐Enyl‐Liganden sind in den letzten Jahren von einer Reihe von Übergangselementen bekannt geworden. Zu ihrer Darstellung geht man von geeigneten Metallhalogeniden oder ‐carbonylen aus, die zumeist mit Allyl‐Verbindungen oder Olefinen zur Umsetzung gebracht werden. Die erhaltenen Substanzen sind fast ausnahmslos diamagnetisch, kristallin oder in organischen Medien gut löslich; sie zeichnen sich durch teilweise bemerkenswerte Stabilität und oft hohe Flüchtigkeit aus. Physikalisch‐chemische Untersuchungsergebnisse bestätigen eindeutig das Vorliegen eines delokalisierten π‐Elektronensystems in den π‐Allyl‐ bzw. π‐Enyl‐Resten. Ihre Bindung an das Zentralatom kann mit derjenigen in Cyclopentadienyl‐Metall‐Komplexen verglichen werden.
Element‐organische Verbindungen (III) Ein neuer Aspekt der π‐Bindung: π‐Komplexbildung in einem Aromaten‐Metallporphyrinähnlichen System [1]
Authors: Tsutsui Minoru
Published: September 2010

In dieser Arbeit wird über die Synthese von Benzol‐bis‐dipyridyl‐chrom‐jodid und Diphenyl‐bis‐dipyridyl‐chrom‐jodid berichtet, die eine neue Klasse von π‐Komplexen vertreten, in welchen das Metallatom von vier Stickstoffliganden, wahrscheinlich in quadratischplaner Anordnung, und einem π‐gebundenen Aromaten umgeben ist.

Besonders für die Chemie von natürlich vorkommenden Verbindungen, wie Metallporphyrinen, Cytochromen, Vitam B12 u. a., kann die Entdeckung der Bildung einer π‐Bindung zwischen einem aromatischen Ring und einem Metall mit vier Stickstoffliganden von Bedeutung sein.
Das elektrochemische Potential der Amalgame
Authors: Jangg G. , Kirchmayr H.
Published: September 2010

Auf Grund thermodynamischer Überlegungen läßt sich eine allgemein gültige Formel für die Berechnung des elektrochemischen Potentials beliebig zusammengesetzter Amalgame angeben. Es werden auch Sonderfälle dieser Gleichung für an Metall gesättigte Amalgame und für Amalgame von Metallen, die mit Quecksilber keine Verbindungen bilden, diskutiert.

Experimentelle Bestimmungen des Potentials verschiedener Amalgame bestätigten die erarbeiteten Formeln. Lediglich das gemessene Potential von Amalgamen extrem wenig in Quecksilber löslicher Metalle sowie das von Amalgamen mit sehr geringer Metallkonzentration weicht vom theoretisch geforderten Wert ab. Die Abweichung ist, was bewiesen werden konnte, auf die leichte Polarisierbarkeit derartiger Amalgame zurückzuführen.
Carborane
Authors: Issleib Kurt , Lindner Rolf , Tzschach Alfred
Published: September 2010

Das Gebiet der Borwasserstoff‐ und Bororganoverbindungen ist nach den grundlegenden Arbeiten A. Stocks über Borwasserstoffe (1912 bis 1936) erst in jüngster Zeit vor allem aus zwei Gründen wieder in den Blickpunkt des Interesses gerückt. So waren es einmal die Suche nach energiereichen Raketentreibstoffen, wobei Borwasserstoff‐Verbindungen eine zentrale Stellung einnahmen, und zum anderen neuere Anschauungen zur chemischen Bindung in Elektronenmangelverbindungen, hier speziell die Interpretation der Strukturen und Bindungsverhältnisse in Borwasserstoffen [1], durch die wesentliche Fortschritte auf dem Gebiet der Bororganoverbindungen erzielt wurden.
Ionenaustauschgleichgewichte an stark sauren Polymerisations‐Austauscherharzen auf Basis p‐Vinylanisol
Authors: Wolf F. , Koch H.
Published: September 2010

Ionenaustauscherharze auf Basis Polyvinylanisol wurden in der Literatur bisher nur als Popcorn‐Polymerisate mit relativ niedriger Kapazität beschrieben [1]. Beachtet man aber die Tatsache, daß bei niedermolekularen aromatischen Verbindungen Alkoxylgruppen auf Grund von Resonanzeffekten einen positiven Einfluß auf die Reaktivität des aromatischen Ringsystems bei elektrophilen Substitutionsreaktionen ausüben, dann sollte auch die Möglichkeit bestehen, vernetzte Copolymerisate auf Basis p‐Vinylanisol‐Divinylbenzol durch Sulfonierung unter optimalen Bedingungen in hochkapazitive Ionenaustauscher zu überführen, deren aromatische Kerne wenigstens teilweise disulfoniert sind. Unsere Arbeiten verfolgten das Ziel, Kationenaustauscherharze auf Basis p‐Vinylanisol mit hoher Austauschkapazität bei guter physikalischer Stabilität herzustellen, diese Harze physikalisch‐chemisch zu charakterisieren und ihre Selektivität bei Ionenaustauschprozessen zu untersuchen. Sämtliche Untersuchungen wurden zu Vergleichszwecken auch mit einem unter gleichen Bedingungen hergestellten Polystyrolharz (10 Mol‐% DVB) und mit zwei Kondensationsharzen auf Basis Anisol‐Triarylmethansulfosäure durchgeführt.
Elektroanalytische Anwendung von Niederschlagsmembranen
Authors: Geyer R. , Syring W.
Published: September 2010

Potentiometrische Verfahren zur Ermittlung von Ionenaktivitäten lassen sich für die Bestimmung mittlerer und hoher Gehalte nutzbringend einsetzen. Bedeutungsvoll für den Wert derartiger Methoden ist, daß sich die gemessenen Potentialdifferenzen für eine relativ leichte Weiterverarbeitung in Regelkreisen anbieten und daher für die Entwicklung automatischer Analysenverfahren sowie zur Steuerung und Regelung von Produktionsprozessen verwendet werden können. Ein Mangel der Potentiometrie besteht allerdings darin, daß nur für wenige Ionenarten reversible Elektroden verfügbar sind.
Über tribochemische Reaktionen einiger technisch wichtiger Metalle mit CO und CO2
Authors: Heinicke G. , Sigrist K.
Published: September 2010

Unter tribochemischer Beanspruchung werden Metalle, wie Aluminium, Magnesium, Eisen, Nickel und Kupfer, durch CO und CO2 oxydiert. Der Kohlenstoff scheidet sich zum Teil als Graphit ab oder reagiert mit den Metallen zum Carbid. Zu Beginn der Bearbeitung erhält man Reaktionen von nullter Ordnung. Nach längerer Reaktionsdauer fällt die Reaktionsgeschwindigkeit ab, und es stellt sich ein stationärer Zustand, ein sog. tribochemisches Gleichgewicht, ein.

Für die Oxydation des Kupfers durch CO und CO2, sind die thermodynamisch berechneten Reaktionsarbeiten positiv. Scheinbar im Widerspruch hierzu stehen die beobachteten tribochemischen Umsetzungen am Kupfer. Eine Deutung wird auf der Grundlage des Magma‐Plasma‐Modells von P. A. Thiessen gegeben.

Auf die technische Bedeutung der untersuchten Reaktionen für Reibungs‐, Schmierungs‐ und Verschleißprozesse wird hingewiesen.
Cubane — polyedrische Verbindungen mit Würfelstruktur
Authors: Tzschach Alfred , Balszuweit Arno
Published: September 2010

In jüngster Zeit führten photochemische Reaktionen in der organischen Chemie zu einer Vielzahl von Molekülen mit polyedrischer Struktur [1], von denen jene mit Würfelstruktur auf Grund besonderer Bindungsverhältnisse und Verbreitung auch im anorganischen Bereich zunehmendes Interesse beanspruchen. Im Rahmen der vorliegenden Übersicht sollen anorganische

In dieser Übersicht sollen nur Verbindungen behandelt werden, die auch in Lösung tetramer auftreten. Substanzen wie beispielsweise MO tert.‐C4H9.(M = K, Rb, Cs) [vgl. Weiss, E., Alsdorf, H., u. H. Kühr: Angew. Chem. 79, 816 (1967)], die offensichtlich nur in festem Zustand tetramere Struktureinheiten bilden, bleiben unberücksichtigt.

) und organische Verbindungen mit Cubanstruktur (A) sowie Verbindungen mit cubanähnlichen Strukturen (B) und (C) und deren Umlagerungen behandelt werden.
Significance of Initial Aortic Aneurysm Pressure Sensor Readings Varies with Aortic Endograft Design
Authors: Shrikhande Gautam , Khan Sikandar , Hussain Hafiz , Menezes Alicia , McKinsey James , Bush Harry
Published: September 2010

Background

The differences in implantable pressure sensor aneurysm sac readings were compared following endovascular aneurysm repair (EVAR) among three different stent grafts.

Methods

From January 2006 to March 2009, 51 aortic stent grafts were implanted along with the Endosure sensor. Grafts used were Zenith, Talent, and Excluder. In the present retrospective study, pulse ratios were measured intraoperatively before and after aneurysm sac exclusion and in follow‐up (within 30 days). Analysis of variance was used to determine significance.

Results

The average aneurysm size that was repaired was 5.75 cm (range: 4–8.5 cm); 41 patients (80.4%) being male with an average age of 76.3 years (range: 58–90 years). Thirty‐four grafts were Zenith, 9 were Talent, and 8 were Excluder. The average pre‐aneurysm exclusion pulse ratios for the Zenith, Talent, and Excluder were 1.00, 1.08, and 0.95 (p = 0.18), respectively. The average post‐aneurysm exclusion pulse ratios were 0.34, 0.67, and 0.35, respectively (p = 0.003). Pulse ratios at the time of follow‐up (within 30 days) were 0.17, 0.22, and 0.11, respectively (p = 0.44). Nine of 51 (17.6%) patients had a reduction of pulse ratio of less than 30% after endograft implantation. Five of those 9 patients (55.5%) had the Talent endograft, although there was no angiographic evidence of endoleak.

Conclusions

The Talent graft has significantly higher pulse ratios following endograft implantation despite having no angiographic evidence of endoleak when compared to the Zenith and Excluder grafts. However, the pulse ratios decreased to levels similar to Zenith and Excluder within 30 days of endograft implantation. This suggests that the Talent endograft may have increased porosity initially. If pulse ratios do not appropriately decrease immediately after device implantation, further angiographic imaging may not be necessary if no obvious endoleak is seen.
Genetic Counseling in a Busy Pediatric Metabolic Practice
Authors: Hartley Jessica N. , Greenberg Cheryl R. , Mhanni Aizeddin A.
Published: September 2010

Patients with inborn errors of metabolism and their families require unique clinical care including management of acute illnesses, screening for long term complications, discussion of the etiology of the condition, connections to social supports, and clarification of the recurrence risks and prenatal testing and treatment options. Our multidisciplinary pediatric metabolic clinic combines the skills of metabolic geneticists, pediatric dieticians, social workers, clinical pharmacists, nurses and genetic counselors to provide optimal and well‐rounded care for our patients and their families. Given the inherited nature of most inborn errors of metabolism and the necessary long‐term management for these disorders, the genetic counselor's role in this clinic setting is integral in providing ongoing support and education for patients and their families. This includes coping with the disease burden, helping patients and families adapt to a condition in the family and ensuring adequate understanding of the genetic risks and the available prenatal diagnostic and reproductive choices. Our clinic provides services to a large geographic area with many isolated populations where unique metabolic diseases are highly prevalent secondary to a founder effect. In this paper, we share our experience in providing longitudinal care to children with complex medical needs due to metabolic disorders and highlight the role of the genetic counselor in this clinic setting.
Novel Strategy to Fabricate PLA/Au Nanocomposites as an Efficient Drug Carrier for Human Leukemia Cells in Vitro
Authors: Li Jingyuan , Chen Chen , Wang Xuemei , Gu Zhongze , Chen Baoan
Published: September 2010

Poly (lactic acid) (PLA) polymer has the promising applications in the biomedical field because of its biodegradability and safe elimination. In this study, we have explored the bio-application of new nanocomposites composed with PLA nanofibers and Au nanoparticles as the potential drug carrier for an efficient drug delivery in target cancer cells. The results demonstrated that the anticancer drug daunorubicin could be efficiently self-assembled on the surface of PLA/Au nanocomposites and the synergistic enhancement of PLA/Au nanocomposites conjugated with daunorubicin into drug-sensitive K562 and drug-resistant leukemia K562/AO2 cells could be obviously observed by MTT assay and confocal fluorescence microscopy studies. These observations suggest that the new nanocomposites could readily induce daunorubicin to accumulate and uptake in target leukemia cells and increase the drug's cytotoxicity. Especially, the PLA/Au nanocomposites could significantly facilitate the cellular drug absorbtion of daunorubicin into drug-resistant K562/AO2 cells and efficiently inhibit the cancer cell proliferation. This raised the possibility to utilize the PLA/Au nanocomposites as a new effective additive agent to inhibit the drug resistance and thus as a novel strategy to sensitively track the respective cancer cells.
Cancer: evolutionary, genetic and epigenetic aspects
Authors: Lichtenstein Anatoly V.
Published: September 2010

There exist two paradigms about the nature of cancer. According to the generally accepted one, cancer is a by-product of design limitations of a multi-cellular organism (Greaves, Nat Rev Cancer 7:213–221, 2007). The essence of the second resides in the question “Does cancer kill the individual and save the species?” (Sommer, Hum Mutat 3:166–169, 1994). Recent data on genetic and epigenetic mechanisms of cell transformation summarized in this review support the latter point of view, namely that carcinogenesis is an evolutionary conserved phenomenon—a programmed death of an organism. It is assumed that cancer possesses an important function of altruistic nature: as a mediator of negative selection, it serves to preserve integrity of species gene pool and to mediate its evolutionary adjustment. Cancer fulfills its task due apparently to specific killer function, understanding mechanism of which may suggest new therapeutic strategy.
MULTIVARIATE ECOGARCH PROCESSES
Authors: Haug Stephan , Stelzer Robert
Published: September 2010

A multivariate extension of the exponential continuous time GARCH (p, q) model (ECOGARCH) is introduced and studied. Stationarity and mixing properties of the new stochastic volatility model are investigated, and ways to model a component-wise leverage effect are presented.
Potential Benefits of GPS/GLONASS/GALILEO Integration in an Urban Canyon – Hong Kong
Authors: Ji Shengyue , Chen Wu , Ding Xiaoli , Chen Yongqi , Zhao Chunmei , Hu Congwei
Published: September 2010

With the existing GPS, the replenishment of GLONASS and the launching of Galileo there will be three satellite navigation systems in the future, with a total of more than 80 satellites. So it can be expected that the performance of the global navigation satellite system (GNSS) will be greatly improved, especially in urban environments. This paper studies the potential benefits of GPS/GLONASS/Galileo integration in an urban canyon – Hong Kong. The navigation performances of four choices (GPS alone, GPS+GLONASS, GPS+Galileo and GPS+GLONASS+Galileo) are evaluated in terms of availability, coverage, and continuity based on simulation. The results show that there are significant improvements in availability, coverage and continuity, by using GPS+GLONASS+Galileo compared with the other choices. But the performance is still not good enough for most navigation applications in urban environments.
An Intelligent Spatial Collision Risk Based on the Quaternion Ship Domain
Authors: Wang Ning
Published: September 2010

In this paper, a novel ship domain model termed quaternion ship domain (QSD) is proposed. Unlike other ship domains, the proposed QSD is more dependable and more flexible for navigators to use to make decisions. The main characteristics are that: the domain size is determined by the quaternion including four radii, i.e. fore, aft, starboard and port, which sufficiently take factors affecting the domain (i.e. ship manoeuvring capability, speeds and courses, etc.) into account; and that the domain shape is modelled by another parameter which makes the QSD more flexible since the ship boundary could not only be linear or nonlinear, but also be thin or fat. In order to reasonably relate the proposed QSD to practical applications, i.e. collision risk assessment, collision avoidance and trajectory planning, etc., a fuzzy QSD (FQSD) has been developed by using fuzzy sets. As a result, fuzzy boundaries rather than crisp ones in the FQSD are more practical and more convenient for navigators to understand and judge since uncertainty and fuzzy information have been merged into the FQSD. Furthermore, concepts of longitudinal and lateral risk based on the FQSD have been introduced to estimate the spatial collision risk (SCR) for the ships encountered. Finally, several computer simulations have been conducted on various encounter situations and comparative studies with other ship domains have been comprehensively analyzed. Simulation results demonstrate that the proposed QSD is more effective and more flexible than other ship domains, and that the intelligent SCR based on the FQSD are reasonable and dependable.
Adding the Human Element to Ship Manoeuvring Simulations
Authors: Aarsæther Karl Gunnar , Moan Torgeir
Published: September 2010

Time-domain simulation of ship manoeuvring has been utilized in risk analysis to assess the effect of changes to the ship-lane, development in traffic volume and the associated risk. The process of ship manoeuvring in a wider socio-technical context consists of the technical systems, operational procedures, the human operators and support functions. Automated manoeuvring simulations without human operators in the simulation loop have often been preferred in simulation studies due to the low time required for simulations. Automatic control has represented the human element with little effort devoted to explain the relationship between the guidance and control algorithms and the human operator which they replace. This paper describes the development and application of a model for the human element for autonomous time-domain manoeuvring simulations. The method is applicable in the time-domain, modular and found to be capable of reproducing observed manoeuvre patterns, but limited to represent the intended behaviour.
THE INADEQUACY OF A PROPOSED PARACONSISTENT SET THEORY
Authors: BJØRDAL FRODE
Published: September 2010

We show that a paraconsistent set theory proposed in Weber (2010) is strong enough to provide a quite classical nonprimitive notion of identity, so that the relation is an equivalence relation and also obeys full substitutivity: a = b → (F(a) → F(b)). With this as background it is shown that the proposed theory also proves ∀x(x ≠ x). While not by itself showing that the proposed system is trivial in the sense of proving all statements, it is argued that this outcome makes the system inadequate.
A SEQUENT CALCULUS ISOMORPHIC TO GENTZEN’S NATURAL DEDUCTION
Authors: VON PLATO JAN
Published: September 2010

Gentzen’s thesis proved the equivalence of natural deduction, sequent calculus, and axiomatic logic through a cycle of translations. Mysteriously, even normal derivations in natural deduction got translated into sequent derivations with cuts. It is shown that the insertion of special cuts, whenever left conjunction, left implication, or left universal quantification in sequent calculus is used, results in sequent calculus derivations isomorphic to those in Gentzen’s natural deduction. Thereby the appearance of the cuts in translation is explained.
Flare location on the solar disk: Modeling the thermosphere and ionosphere response
Authors: Qian Liying , Burns Alan G. , Chamberlin Phillip C. , Solomon Stanley C.
Published: September 2010

Solar flare enhancements to the soft X‐ray (XUV) and extreme ultraviolet (EUV) spectral irradiance depend on the location of the flare on the solar disk. Most emission lines in the XUV region (∼0.1 to ∼25 nm) are optically thin and are weakly dependent on the location of the flare, but in the EUV region (∼25 to ∼120 nm), many important lines and continua are optically thick, so enhancements are relatively smaller for flares located near the solar limb, due to absorption by the solar atmosphere. The flare irradiance spectral model (FISM) was used to illustrate these location effects, assuming two X17 flares that are identical except that one occurs near disk center and the other near the limb. FISM spectra of these two flares were used as solar input to the National Center for Atmospheric Research (NCAR) thermosphere‐ionosphere‐mesosphere electrodynamics general circulation model (TIME‐GCM) to investigate the ionosphere/thermosphere (I/T) response. Model simulations showed that in the E region ionosphere, where XUV dominates ionization, flare location does not affect I/T response. However, flare‐driven changes in the F region ionosphere, total electron content (TEC), and neutral density in the upper thermosphere, are 2–3 times stronger for a disk‐center flare than for a limb flare, due to the importance of EUV enhancement. Flare location did not affect the timing of the ionospheric response, but the thermospheric response was ∼20 min faster for the disk‐center flare. Model simulations of I/T responses to an X17 flare on 28 October 2003 were consistent with measurements of TEC and neutral density changes.
Time series of bio‐optical properties in a subtropical gyre: Implications for the evaluation of interannual trends of biogeochemical properties
Authors: Lee ZhongPing , Shang Shaoling , Hu Chuanmin , Lewis Marlon , Arnone Robert , Li Yonghong , Lubac Bertrand
Published: September 2010

With a validated Quasi‐Analytical Algorithm, an 11 year (1998–2008) monthly time series of the primary optical properties of waters in the center of the South Pacific gyre was developed from Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS). Also derived are chlorophyll a (Chl a) concentrations with the operational empirical algorithms for SeaWiFS and MODIS. The optical properties include the absorption coefficient (at 443 nm) of phytoplankton (aph) and that of the combination of detritus and gelbstoff (adg). From these time series, we further derived their annual background (summer low) and seasonal intensity (the difference between winter high and summer low). These time series show that (1) the optical properties have different seasonal and interannual variations, indicating different dynamics of these properties in the subtropical gyre; (2) there is a decreasing trend (r2 = 0.24) of the background aph in the 1998–2008 period and an increasing trend of the aph seasonal intensity (r2 = 0.11) for this period, and both trends are not statistically significant; (3) the aph time series agrees with the Chl a time series at the seasonal scale, but differs with respect to interannual variations; and (4) different interannual trends could be inferred with different time frames. These results emphasize that it is difficult to draw unequivocal conclusions about long‐term trends of biogeochemical properties in the oceans with the current relatively short bio‐optical records. To clarify and predict such trends, it is critical to get a full account of the forces that are responsible for the seasonal and interannual variations of these properties.
Examining the large‐time wellbore flux of constant head test
Authors: Yeh Hund‐Der , Wang Chih‐Tse , Llewellyn Smith Stefan G.
Published: September 2010

The function 1/[p ln (p/λ)] comes from the wellbore flux solution in the Laplace domain for a constant head aquifer test when the Laplace variable p is small. The resulting inverse Laplace transform v(λt), representing the large‐time wellbore flux, grows exponentially with time, which does not agree with the physical behavior of the wellbore flux. Based on this result, Chen and Stone (1993) asserted that the well‐known relationship of small p–large t may fail to yield the correct large‐time asymptotic solution. Yeh and Wang (2007) pointed out that the large‐time wellbore flux is not ν(λt) if the inversion of 1/[p ln (p/λ)] is subject to the constraint Re p > λ. Chen (2009) subsequently questioned the necessity of imposing this constraint on the Laplace transform in the inversion of the large‐time wellbore flux. Motived by Chen's comment, we reexamine the inversion of 1/[p ln (p/λ)] and demonstrate that this contradictory issue originates from a spurious pole introduced when applying the small p–large t correspondence to the Laplace domain solution. We explain why this occurs and why the actual wellbore flux at large times is proportional to the function N(λt), known as Ramanujan's integral. The function N(λt) does decay at large time, which agrees with the steady state wellbore flux of the constant head test.
Report Calls for Climate Panel Reforms
Authors: Showstack Randy
Published: September 2010

The process by which the Intergovernmental Panel on Climate Change (IPCC) operates and produces its periodic assessments requires some fundamental changes so that it is more effective and transparent, according to a 30 August report of the Inter‐Academy Council (IAC). The report recommends modernizing the IPCC management structure, including imposing a limit of one term for the IPCC chair and other key IPCC leaders, to “ensure a greater infusion of fresh perspectives on the assessments.” The report notes that a two‐term appointment, for a total of 12 years, “is too long for a field as dynamic and contested as climate change.” Current IPCC chair Rajendra Pachauri is in his second term and has held the position since 2002.
Christine McEntee Takes Office as AGU Executive Director
Authors: Tretkoff Ernie
Published: September 2010

In a historic transition event, AGU staff and volunteer leadership welcomed incoming executive director Christine W. McEntee and said farewell to outgoing interim executive director Robert Van Hook. The event, with the theme “A Bridge to the Future: From Strength to Strength,” took place at AGU headquarters in Washington, D.C., on 30 August.

McEntee comes to AGU from the American Institute of Architects, where she served as executive vice president and chief executive officer since 2006. She is the Union's third executive director.
Global modeling of equatorial plasma bubbles
Authors: Huba J. D. , Joyce G.
Published: September 2010

The NRL three‐dimensional ionospheric simulation code SAMI3 is used to model the onset and evolution of equatorial spread F (ESF). SAMI3 is a comprehensive ionosphere model that has been modified to self‐consistently solve for the global neutral wind driven dynamo electric field as well as the gravity driven electric field associated with plasma bubbles. The latter is achieved with a high resolution longitudinal grid in the pre‐ to post‐sunset sector (i.e., 1630 MLT–2230 MLT). Initial results from the new simulation model are presented. It is shown that ESF can be triggered by pre‐sunset ionospheric density perturbations, and that an existing ESF bubble can trigger a new bubble.
Thermospheric composition variations due to nonmigrating tides and their effect on ionosphere
Authors: Zhang Yongliang , England Scott , Paxton Larry J.
Published: September 2010

The TIMED/GUVI thermospheric composition (O/N2 ratio) over 2009 reveals clear wave‐3 (summer season) and wave‐4 (Fall season) longitudinal dependence. The wave peak to valley varies from 7 to 11% of the background O/N2. The low Kp (yearly mean of 0.9) and low solar EUV flux indicates that the wave features were not caused by geomagnetic activity or solar EUV variation. A more likely explanation is nonmigrating diurnal eastward propagating DE2 and DE3 tides. Model calculations indicate that a 10% variation in O/N2 makes 1/3 contribution to the nightside equatorial 135.6 nm intensities compared to the variation due to the E‐region dynamo electric field. This study confirms that nonmigrating tides can penetrate toward the upper thermosphere, both O/N2 and the E‐region dynamo should be considered in analyzing ionospheric density variations due to nonmigrating tides. Comparison with MSIS results indicates that the nonmigrating tides have stronger effect on O/N2 than the migrating tides.
Toward understanding slip inversion uncertainty and artifacts
Authors: Zahradník Jiří , Gallovič František
Published: September 2010

The main concept of seismic source tomography, the projection lines along which the observed signals are back‐projected to the fault, is extended to complete wavefields. The so‐called “dynamic projection strips” (DPSs) are defined, and a method to construct the strips from individual waveforms is described. In this way, each individual station role in the inversion can be better understood. Synthetic models with two asperities (two unilateral and one bilateral rupture scenarios) are used as examples. They are analyzed using two independent slip inversion methods with similar results, bias of the rupture speed for all scenarios and a strong false asperity in the middle of the bilateral fault. Both artifacts can be explained by the DPS analysis as inherent nonuniqueness of the inverse problem due to the joint effect of the two true asperities. Removal of some slip artifacts by imposing various constraints is discussed, but most of the constraints are hardly applicable in practice. As such, it is recommended to look at least for possible indications of the most significant inversion artifacts. This seems to be feasible through combining DPSs derived from real data and synthetic models of various rupture scenarios for a given fault and stations. The ideas are applied to the Movri Mountain earthquake in Greece, Mw6.3, 8 June 2008. It appears that the earthquake was predominantly unilateral, however with a nonunique space‐time slip pattern. Few equivalent nonsmooth models, all fitting the data equally well, are illustrated.
Abnormal behavior of supercooled liquid region in bulk-forming metallic glasses
Authors: Park E. S. , Na J. H. , Kim D. H.
Published: September 2010

A metallic glass is often viewed as an amorphous alloy exhibiting a single endothermic reaction in the supercooled liquid region (SCLR, ΔTx=Tx−Tg). Here we discuss the origin and consequences of abnormal behavior of SCLR in various bulk-forming metallic glasses (BMGs). The two-stage-like endothermic reaction in Ni-based, Cu-based, Zr-based, and Mg-based BMGs can originate from the local immiscibility of liquids, which is closely related to chemical heterogeneity in as-cast BMG. These inflections can be attributed to the overlap of the exothermic reaction for the formation and growth of clusters in SCLR. The abnormal behavior of SCLR can be modulated by controlling cooling rate as well as by tailoring alloy composition, with the consequence that the modulated local heterogeneity in these BMGs can lead to enhanced flexibility of the BMGs. This correlation assists in understanding toughening mechanism and in guiding alloy design to alleviate brittleness of BMGs.