bluuebunny/crossref_metadata_2025 huggingface dataset:
Das erste 1, 3, 4, 6‐Tetraphospha‐1, 5‐hexadien, ein Molekül mit fluktuierenden Bindungen (identische Tetraphospha‐Cope‐Umlagerung) und Konfigurationsisomerie
Authors: Appel Rolf , Barth Volker , Knoll Fritz , Ruppert Ingo
Published: July 2007

PhPCR—PPh—PPh—CRPPh, R = NPh—SiMe3, zeigt entartete Cope‐Umlagerung und Konfigurationsisomerie. Die deutliche Reaktionsanalogie zwischen diesem Methylenphosphan und entsprechenden Alkenen weist darauf hin, daß hier der (PC)‐Bindung kaum der Ylid‐Charakter der Methylen‐phosphorane zukommt.

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Nucleophil katalysierte Reaktionen von Tricarbonyl(trimethylsilylaren)chrom‐Komplexen mit Elektrophilen
Authors: Effenberger Franz , Schöllkopf Klaus
Published: July 2007

Die Einführung vieler Substituenten in Benzol‐Derivate ist ausgehend von (1) möglich. (1) bildet z. B. mit Ketonen in Gegenwart von KOtBu Produkte, die statt mit SiMe3 mit dem (leicht spaltbaren) –CR2–OSiMe3 substituiert sind

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ortho‐palladierte Dibenzylsulfide und ‐sulfoxide aus Palladiumcarboxylaten
Authors: Rüger Reinhold , Rittner Walter , Jones Peter G. , Isenberg Wilhelm , Sheldrick George M.
Published: July 2007

Geeignete Agentien für die ortho‐Palladierung sind Palladium(II)‐acetat und ‐trifluoracetat. So gelang es, aus diesen Verbindungen und Dibenzylsulfoxid oder Dibenzylsulfid die Komplexe (1) herzustellen. Bisher konnten nur Arylthioketone ortho‐palladiert werden (R = CH3, CF3; X = SO, S)

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Reaktion von Dicarbonyl(cyclopentadienyl)(isobuten)eisentetrafluoroborat mit Diphenylcyclopropenon: Komplexierung ohne Ringöffnung
Authors: Woell James B. , Boudjouk Philip
Published: July 2007

Für die lange postulierten Übergangsmetall‐komplexe mit Diphenylcyclopropenon (1), die Zwischenstufen der Carbonylierung von Acetylenen sein sollen, gibt es jetzt ein gut zu untersuchendes Beispiel: den Komplex (2). Er entsteht aus (1) und [Fe(C5H5)(CO)2(i‐C4H10)]⊕BF4⊖. (1) reagiert mit Übergangsmetallverbindungen fast immer unter Ringöffnung

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Synthese von (±)‐13‐Desoxo‐11‐desoxy‐daunorubicinon
Authors: Krohn Karsten
Published: July 2007

Die als Antibioticum interessierende, natürlich vorkommende Titelverbindung (2) wurde erstmals synthetisiert. Schlüsselschritt war die Cyclisierung des 2,3‐dialkylierten Anthrachinons (1), die mit 70% Ausbeute verlief.

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Vollständige 13C‐NMR‐Signalzuordnung und Strukturbestimmung von Corrinoiden durch 2D‐INADEQUATE und 2D‐13C, 1H‐NMR‐Verschiebungskorrelationen über nJ(C,H)
Authors: Benn Reinhard , Mynott Richard
Published: July 2007

Die Strukturaufklärung von Corrinoiden durch zweidimensionale NMR‐Techniken ist schnell und zuverlässig. So ließen sich beim Cobyrinsäureheptamethylester 1 die NMR‐Signale aller 52 inäquivalenten Kohlenstoffatome zuordnen. Diese Resonanzen sind über einen Bereich von mehr als 17 kHz verteilt; die Kopplungskonstanten 1J(C,C) liegen zwischen 30 und 80 Hz.

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I(py)2BF4, ein neues Reagens: allgemeine Methode für die 1,2‐Iodfunktionalisierung von Olefinen
Authors: Barluenga José , González José M. , Campos Pedro J. , Asensio Gregorio
Published: July 2007

Viele geladene und nichtgeladene Nucleophile (Nu) können mit Hilfe der Titelverbindung 1 an Olefine addiert werden. Es entstehen die 1,2‐funktionalisierten Verbindungen 2, die als Synthesebausteine Verwendung finden können.

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Vortäuschung von CC‐Bindungen durch ungewöhnlich große 2JCC‐Werte – ein Problem bei der Anwendung der INADEQUATE‐13C‐NMR‐Spektroskopie
Authors: Bauer H. , Buddrus Joachim , Auf der Heyde Wolfgang , Kimpenhaus Wolfgang
Published: July 2007

Die Bestimmung der Konstitution organischer Verbindungen über 13C13C‐Kopplungen ist eine verhältnismäßig neue, erfolgreiche Methode. Wie sich jedoch bei chlorierten Ketonen zeigt, speziell bei Cyclobutenon‐Derivaten wie 1, ist nicht jede Kopplungskonstante oberhalb ca. 25 Hz ein Indiz für eine CC‐Bindung. 2JC−2, C−4 von 1 beträgt 64.1 Hz!

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Strontium‐ und Bariumalkoxostannate(II) ‐ Moleküle mit S6‐Symmetrie
Authors: Veith Michael , Käfer Dieter , Huch Volker
Published: July 2007

Eine quantitative Trennung von Calcium und Strontium ermöglicht die Umsetzung von M(OtBu)2 (MSr, Ca) mit [Sn(OtBu)2]2 in Benzol (!). Das Strontiumsalz geht quantitativ in Lösung, das Strontiumsalz geht quantitativ in Lösung, das Calciumsalz bleibt zurück. Dabei entsteht der rechts abgebildete Polycyclus, eine Molekülverbindung, die sogar in Hexan löslich ist und deren Struktur an die von SrO erinnert.

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Organische Synthese bei hohen Temperaturen: Gasphasen‐Strömungsthermolyse
Authors: Karpf Martin
Published: July 2007

Die bevorzugte Durchführung organischer Synthesen bei möglichst tiefen Temperaturen beruht auf der an vielen Beispielen bestätigten und auch theoretisch begründeten Annahme, daß die Selektivität häufig mit sinkender Temperatur zunimmt. Mangelnde Selektivität ist nicht das einzige Problem von Hochtemperaturreaktionen, hinzu kommt unter anderem die oft begrenzte thermische Stabilität der an der Umwandlung nicht direkt beteiligten funktionellen Gruppen und Strukturelemente. Trotz dieser Einschränkungen lassen sich die Vorteile hoher Temperaturen, vor allem dank der in den letzten Jahren stark erweiterten Kenntnisse der Mechanismen dynamischer Gasphasenprozesse, für die gezielte organische Synthese nützen. In diesem Fortschrittsbericht wird das Synthesepotential der „Gasphasen‐Strömungsthermolyse”︁ aus der Sicht des präparativ arbeitenden Chemikers anhand typischer Anwendungsbeispiele beschrieben.
Ein 1‐Oxa‐2‐nickela‐5‐cyclopentanon aus Ethen und Kohlendioxid; Herstellung, Struktur und Reaktivität
Authors: Hoberg Heinz , Peres Yolande , Krüger Carl , Tsay Yi‐Hung
Published: July 2007

Eine Schlüsselstellung für Nio‐induzierte CC‐Verknüpfungen zwischen Alkenen und CO2 kommt dem Komplex 1 zu, der als Ligand 1,8‐Diazabicyclo[5.4.0]undec‐7‐en (DBU) enthält. Die Ni–C‐Bindung von 1 ist weiteren, regioselektiven Insertionsreaktionen mit Alkenen zugänglich. Der Nickelacyclus wird dadurch zu einem Modellkomplex für das Studium Ni‐katalysierter Reaktionen.

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Supraleitung — eine neue Klassifizierung der chemischen Bindung im Festkörper läßit ihr Auftreten verstehen
Authors: Urland Werner
Published: July 2007

Das Zusammenspiel von Elektronendelokalisation, ‐lokalisation und ‐korrelation mit etwa gleichen Energiebeiträgen ist für das Auftreten von Supraleitung entscheidend. Als Weiterentwicklung der Vorstellungen anderer Wissenschaftler (vor allem von Wooley und Anderson) wird eine Art Phasendiagramm präsentiert, bei dem Feststoffe nach den Energien der drei elektronischen Wechselwirkungen EDel, ELok und EKorr eingeteilt werden. Supraleiter befinden sich dabei in der Nähe eines „Tripelpunkts”︁.
Zweidimensionale NMR‐Spektroskopie, Grundlagen und Übersicht über die Experimente
Authors: Kessler Horst , Gehrke Matthias , Griesinger Christian
Published: July 2007

Eine genaue Kenntnis der Struktur, Dynamik und Reaktionsweise von Molekülen ist der Schlüssel zum Verständnis ihrer Funktionen und Eigenschaften. Die NMR‐Spektroskopie hat sich durch die Einführung zweidimensionaler Verfahren zur bedeutendsten Methode entwickelt, um derartige Informationen über Moleküle in Lösung zu erhalten. Es steht nunmehr ein ganzes Arsenal von Aufnahmetechniken zur Verfügung, deren erfolgreiche Anwendung aber nicht nur die entsprechende apparative Ausstattung, sondern auch die richtige Auswahl der Experimente einschließlich der optimalen Meßparameter und natürlich auch die sorgfältige Auswertung der Spektren voraussetzt. In diesem Beitrag werden die Grundlagen der modernen NMR‐Spektroskopie vorgestellt, und es wird gezeigt, daß es mit dem Produktoperatorformalismus möglich ist, die Pulsfolgen der NMR‐Spektroskopie qualitativ und quantitativ zu verstehen. Nur ganz wenige, leicht verständliche Annahmen muß ein potentieller Anwender dieser Methoden kennenlernen, um mit ihnen vertraut zu werden. Wir wollen den Produktoperatorformalismus ebenso wie die für das Verständnis der Pulsfolgen unabdingbaren Phasencyclen auf einfache Weise einführen und den Umgang mit ihnen bei der Besprechung verschiedener 2D‐NMR‐Techniken üben. Eine Übersicht über die wichtigsten Pulstechniken bildet den zweiten Teil des Beitrags.
Elektronendichte, Deformationsdichte und chemische Bindung
Authors: Schwarz W. H. Eugen , Ruedenberg Klaus , Mensching Lothar , Miller Lance L. , Jacobson R. , Valtazanos Petros , Von Niessen Wolfgang
Published: July 2007

Freie Atome sind nicht notwendigerweise rund, und Atome in einem Molekül sind durch ihre Position und ihre Ausrichtung bestimmt. Erst wenn dies berücksichtigt wird, erhält man gut interpretierbare Differenzdichten. So führt für HF, bei dem konventionelle Differenzdichten die experimentell gesicherte kovalente Bindung nicht erklären können, ein ausgerichtetes F‐Atom zu nebenstehender Differenzdichtekarte.

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Von 2,5‐Dihydropyrazinen zu 2H‐1,4‐Diazepinen und von Benzodihydroarenen zu Benzocyclohepten‐Derivaten, Strukturvarianten des Antidepressivums Protriptylin
Authors: Schöllkopf Ulrich , Mittendorf Joachim
Published: July 2007

Eine Hetero‐Norcaradien‐Cycloheptatrien‐Umlagerung und eine außergewöhnlich schnelle transanulare [1,5]‐sigmatrope Wasserstoffverschiebung sind die Schlüsselschritte bei der baseinduzierten Ringerweiterung der Bislactimether 1 zu den 2H‐1,4‐Diazepinen 2. Die Ringerweiterung ist auch bei analogen all‐Kohlenstoffverbindungen möglich und führt beispielsweise von Dihydroanthracenen zu neuen Strukturvarianten des Antidepressivums Protriptylin wie 3. Beispiele für R1 – R3: H, Me, OMe, Ph, CH2Ph.

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Isolierung einer L‐stereospezifischen N‐Acyl‐L‐prolin‐Acylase und ihre Verwendung als Katalysator in der Organischen Synthese
Authors: Groeger Ulrich , Drauz Karlheinz , Klenk Herbert
Published: July 2007

Mikrobiologisches Screening führte zur Selektion des Mikroorganismus Comamonas testosteroni. Dieses Bakterium produziert beim Wachstum in Gegenwart von N‐Acetyl‐L‐prolin das Enzym N‐Acyl‐L‐prolin‐Acylase. Das bis 70°C thermostabile Enzym (Molekulargewicht 380 ± 40 kDa, acht identische Untereinheiten) hydrolysiert bei pH‐Werten zwischen 5 und 10 stereospezifisch N‐Acetyl‐L‐prolin und ermöglicht so die enzymatische Racematspaltung von D,L‐Prolin.
Synthese und Struktur neuer Cu‐Cluster: [Cu30−xSe15(PiPr3)12] (x = 0,1) und [Cu36Se18(PtBu3)12]
Authors: Fenske Dieter , Kraustscheid Harald , Balter Silke
Published: July 2007

Anders als das System Phosphan/AgCl reagiert das System Phosphan/CuCl mit Se(SiMe3)2 unterhalb 20°C in Ausbeuten von 60% zu metallreichen Clusterkomplexen. Oberhalb 100°C bilden sich dagegen binäre Kupferselenide. Die Verbindungen 1–3 konnten kristallstrukturanalytisch charakterisiert werden. Dabei handelt es sich um die größten bisher bekannten Cu‐Clusterverbindungen. Die Strukturen von 1 und 2 zeigen, daß ein Clustergerüst vorliegt, dessen Polyederflächen von μ4‐Se‐, μ5‐Se‐ und μ6‐Se‐Liganden bedeckt sind.

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Kooperative Wechselwirkungen bei der molekularen Erkennung — die Bindung von Diaminen an eine Tetracarbonsäure
Authors: Ebmeyer Frank , Rebek Julius
Published: July 2007

Ein allosterischer Effekt scheint dafür verantwortlich zu sein, daß das Gastmolekül 1 mit Hydrazin, Ethylendiamin und 1,4‐Diazabicyclo[2.2.2]octan (DABCO) 1:2‐Komplexe bildet, wobei die zweite Assoziationskonstante um den Faktor 50, 200 bzw. 2 größer ist als die erste. Diese positive kooperative Wechselwirkung ist in den ersten beiden Fällen viel stärker als bei ditopen Kronenethern.

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Retrofit of a H2 S selective amine absorber using MellapakPlus structured packing
Authors: Shiveler Glenn , Solis Geronimo Sixtos , Peña Gonzalez Luis Horacio , Bueno Marcelo Lara
Published: July 2007

A major natural gas amine sweetening plant was retrofitted with high‐performance MellapakPlus structured packing in place of valve trays in its 1219 mm (48 inch) diameter amine absorber in order to increase gas capacity and to selectively remove H2S and improve slippage of CO2 using generic methyldiethanolamine (MDEA) amine solvent. The retrofit of the amine absorber was successful, and it achieved the primary objective of improved gas handling capacity and increased H2S selectivity. During the six months of operation, the unit regularly achieved 80% slippage of CO2 while selectively removing H2S to pipeline specification. This paper provides an overview of the gas sweetening plant operation following the retrofit, with performance data obtained for variable inlet feed conditions. This paper includes observations regarding changes in amine quality, reduction of amine consumption, issues with amine degradation, amine salt contamination, experience with minor amounts of fouling and the utilization of an anti‐foaming agent. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Continuous operation of a chemical heat pump
Authors: Ogura Hironao , Yasuda Sotaro , Otsubo Yasufumi , Mujumdar Arun S.
Published: July 2007

In this experimental study, chemical heat pump (CHP) characteristics for heat storage and heat release in repetitive operation were examined. The input/output heat of the CHP in repetitive operation was found to be controlled by the special pressure adjustment procedure such as instant vacuuming or additional vacuuming for pressure‐temperature control of the CHP reactor. In the case of the CaO/H2O/Ca(OH)2 hydration/dehydration system, the CHP is found to produce controlled‐temperature hot/cold heat in a repetitive operation using chemically stored energy during both heat‐storing and heat‐releasing steps. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Dispersion of nanoscale BaTiO3 suspensions by a combination of chemical and mechanical grinding/mixing processes
Authors: Ying Kuo‐Liang , Hsieh Tsung‐Eong
Published: July 2007

The colloidal stability of aqueous nanometer‐ and micrometer‐scale barium titanate (BaTiO3) utilizing poly (methacrylic acid) (PMAA‐Na) and polyacrylamide/(α‐N,N‐dimethyl‐N‐acryloyloxyethyl)ammonium ethanate (PDAAE) was investigated. In addition to chemical dispersants, the effects of mechanical milling using either conventional ball milling or nanogrinding/‐mixing on the dispersion of BaTiO3 suspensions were also studied. Characterization of the particle size distribution (d50), viscosity, and morphology of BaTiO3 particles in the suspensions revealed that a sole chemical dispersant or mechanical milling was insufficient to achieve nanometer‐scale dispersion. The best dispersion results were obtained with a combination of PMAA‐Na dispersant and nanogrinding/‐mixing, which could provide sufficient electronic repulsive force and shear force to disperse the 80‐nm BaTiO3 powders uniformly in the aqueous suspension. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Isothermal crystallization kinetics and melting behaviors of nanocomposites of poly(trimethylene terephthalate) filled with nano‐CaCO3
Authors: Run Mingtao , Yao Chenguang , Wang Yingjin , Gao Jungang
Published: July 2007

The isothermal crystallization and subsequent melting behavior of poly(trimethylene terephthalate) (PTT) composites filled with nano‐CaCO3 were investigated at designated temperatures with differential scanning calorimetry. The Avrami equation was used to fit the isothermal crystallization. The Avrami exponents were determined to be 2–3 for the neat PTT and PTT/CaCO3 composites. The particles of nano‐CaCO3, acting as nucleating agents in the composites, accelerated the crystallization rate, with the half‐time of crystallization decreasing or the growth rate constant (involving both nucleation and growth rate parameters) increasing. The crystallization activation energy calculated from the Arrhenius formula was reduced as the nano‐CaCO3 content increased from 0 to 2%, and this suggested that nano‐CaCO3 made the molecular chains of PTT easier to crystallize during the isothermal crystallization process. Subsequent melting scans of the isothermally crystallized composites exhibited triple or double melting endotherms: the greater the content was of nano‐CaCO3, the lower the temperature was of the melting peak. The degree of crystallization deduced from the melt enthalpy of composites with the proper concentration of nano‐CaCO3 was higher than that of pure PTT, but it was lower when the nano‐CaCO3 concentration was more than 2%. The transmission electron microscopy pictures suggested that the dispersion state of nano‐CaCO3 particles in the polymer matrix was even when its concentration was no more than 2%, whereas some agglomeration occurred when its concentration was 4%. Polarized microscopy pictures showed that much smaller or less perfect crystals formed in the composites because of the interaction between the molecular chains and nano‐CaCO3 particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Dye–fiber interactions in PET fibers: Hydrogen bonding studied by IR‐spectroscopy
Authors: Clerck Karen De , Rahier Hubert , Mele Bruno Van , Westbroek Philippe , Kiekens Paul
Published: July 2007

Dye–fiber interactions are studied in poly (ethylene terephthalate) fibers by FT‐IR spectroscopy. It is shown for the first time that DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) serves as an easy applicable and accurate technique for the study of fibrous structures. This article focuses on the possible hydrogen bond interactions in the dye–fiber system, where the PET fibers are dyed with anthraquinone‐based disperse dyes. The dyes and related anthraquinone structures are studied in both the dilute solution state, the solid state, and as present in the PET fibers. It is proven that 1‐amino anthraquinones show strong “chelate‐type” intramolecular hydrogen bonding in all three states. In the fibers an important supplementary intermolecular hydrogen bonding with the CO groups in the PET fiber is observed. The extend of hydrogen bonding seems to be prone to dye concentration variations. Further analysis by modulated differential scanning calorimetry links the hydrogen bonding to an intrinsic plasticizing effect of the dyes affecting the dye diffusion process. This thus offers a tool for the fundamental understanding of the dyeing process and possible observed differences in dyeing behavior in dye–fiber systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Fluorinated polyether additives to improve the performance of urea–formaldehyde adhesives for wood panels
Authors: Mansouri H. R. , Thomas R. R. , Garnier S. , Pizzi A.
Published: July 2007

Small amounts of fluorinated polyethers, and in particular a nonionic fluorinated polyether, can upgrade considerably the cold‐water swelling and internal bond strength of wood particleboard bonded with urea–formaldehyde (UF) resins. The effect is maximized at an additive concentration of about 0.1 wt % with respect to the adhesive resin solid content. The effect of the fluorinated polyether appears to be greater with older UF resins, which have a more pronounced colloidal state. The mechanism appears to be somewhat related to the reduction of the interfacial tension of the resins, with improved substrate wetting leading to better adhesion. The addition of a fluorinated polyether well in advance of resin use further enhances the improvement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Effects of ultrasonic oscillations on rheological behavior and mechanical properties of novel propylene‐based plastomers
Authors: Peng Bo , Wu Hong , Guo Shaoyun , Lai Shih‐Yaw , Jow Jinder
Published: July 2007

The effects of ultrasonic oscillations on the die pressure, productivity of extrusion, melt apparent viscosity, melt surface appearance, and die swell of novel propylene‐based plastomers were studied in a specially designed ultrasonic oscillations extrusion system developed in our laboratory. The effects of ultrasonic oscillations on molecular weights, tensile strength, and dynamic mechanical properties of extrudates were also studied. The experimental results showed that the presence of ultrasonic oscillations during extrusion could significantly increase the productivity of plastomers at the same die pressure, and reduce die swell and melt fracture such as sharkskin at a given screw rotation speed. The die pressure and apparent viscosity of plastomers remarkably decreased with increasing ultrasonic intensity. Introduction of ultrasonic oscillations into plastomer melts can improve their processibility. The possible mechanism for ultrasonic improvement of rheological behavior was also proposed in this article. Under certain conditions, ultrasound‐assisted extrusion could slightly decrease the glass transition temperature (Tg) and storage modulus of plastomers due to the minor reduction in molecular weights, but showed no significant impact on yield strength and strength at break. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Fiber breakage and dispersion in carbon‐fiber‐reinforced nylon 6/clay nanocomposites
Authors: Zhou Hu , Qian Zhongzhong , Meng Xiangfu , Ding Yanfen , Zhang Shimin , Yang Mingshu
Published: July 2007

In this paper, short carbon‐fiber‐reinforced nylon 6/clay nanocomposites are prepared via melt compounding, and fiber breakage and dispersion during processing are studied. The influences of clay and processing conditions on fiber breakage and dispersion are taken into consideration. It is found that the presence of organoclay can improve fiber dispersion, which is due to dispersion at the nanoscale of exfoliated clay sheets with large aspect ratio. The bimodal distribution of fiber length is observed in fiber‐reinforced nanocomposites, which is similar to that in conventional fiber‐reinforced composites. The improvement of fiber breakage at moderate organoclay loadings is also observed, which is ascribed to the rheological and lubricating effects induced by organoclay. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Liquid chromatography/electrospray ionization mass spectrometry method for the determination of the active metabolite M‐1 of suplatast tosilate in human plasma
Authors: Ding Li , Ding Likun , Zhou Xia , Yang Lin , Wen Aidong
Published: July 2007

A liquid chromatography/electrospray ionization mass spectrometry (LC/ESIMS) method for the determination of 4‐(3‐ethoxy‐2‐hydroxypropoxy) acrylanilide (M‐1), the active metabolite of suplatast tosilate, in human plasma was established. Plasma samples were extracted with diethyl ether, separated on a C18 column with a mobile phase of acetonitrile–10 mm ammonium acetate solution containing 0.1% formic acid (28:72, v/v) and detected by ESIMS. The method was linear over the concentration range 0.15–60.0 ng/mL. The lowest limit of quantification was 0.15 ng/mL. The intra‐ and inter‐run relative standard deviations obtained from three validation runs were all less than 8.6%, and the intra‐ and inter‐run relative errors were all less than 3.1%. The method was successfully applied for the evaluation of pharmacokinetic profiles of M‐1 in healthy volunteers. Copyright © 2007 John Wiley & Sons, Ltd.
Emulation of Racemase Activity by Employing a Pair of Stereocomplementary Biocatalysts
Authors: Gruber Christian C. , Nestl Bettina M. , Gross Johannes , Hildebrandt Petra , Bornscheuer Uwe T. , Faber Kurt , Kroutil Wolfgang
Published: July 2007

Racemization is the key step to turn a kinetic resolution process into dynamic resolution. A general strategy for racemization under mild reaction conditions by employing stereoselective biocatalysts is presented, in which racemization is achieved by employing a pair of stereocomplementary biocatalysts that reversibly interconvert an sp3 to a sp2 center. The formal interconversion of the enantiomers proceeds via a prochiral sp2 intermediate the formation of which is catalyzed either by two stereocomplementary enzymes or by a single enzyme with low stereoselectivity. By choosing appropriate reaction conditions, the amount of the prochiral intermediate is kept to a minimum. This general strategy, which is applicable to redox enzymes (e.g., by acting on R2CHOH and R2CHNHR groups) and lyase‐catalyzed addition–elimination reactions, was proven for the racemization of secondary alcohols by employing alcohol dehydrogenases. Thus, enantiopure chiral alcohols were used as model substrates and were racemized either with highly stereoselective biocatalysts or by using (rarely found) non‐selective enzymes.
Recent Advances in the Benzannulation of Substituted 3‐Alkoxycarbonyl‐3,5‐hexadienoic Acids and 3‐Alkoxycarbonylhex‐3‐en‐5‐ynoic Acids to Polysubstituted Aromatics
Authors: Serra Stefano , Fuganti Claudio , Brenna Elisabetta
Published: July 2007

The benzannulation reactions of substituted 3‐alkoxycarbonyl‐3,5‐hexadienoic and 3‐alkoxycarbonylhex‐3‐en‐5‐ynoic acids offer a straightforward access to various polysubstituted aromatic compounds. The process is very flexible, and can be applied to the regiospecific preparation of oligoaryls, naphthalenes, ring‐fused heterocycles, chiral tetrahydronaphthalenes, C‐aryl‐glycosides and many natural products of different structure. In this Concept article, we highlight the potential of this annulation reaction by illustration of our recent contribution to this field, as well as the studies previous reported by others.
Competitive advantages of the kaisha
Authors: Leonard Jim
Published: July 2007

Editor's Note: Former Competitive Intelligencer editor, Jim Leonard, attended the Japanese Business Study Program (JBSP) in October, 1989. J B S e sponsored by MITI, guides 50 US, Canadian, and EEC people around Japan for 23 days to learn about Japanese business, culture, markets, and mindsets. This article is a revised excerpt from Jim? report on his impression of Japan and the JBSP program.
Processing ideas: An argument for useful text management software
Authors: Meade Bill
Published: July 2007

Low cost, personal computer (PC) based software adapted for competitive intelligence (CI) use can frustrate users because they appear to offer only slightly mare than the sorting and search functions of word processing software. What we would prefer is the capability of finding and manipulating ideas rather than words. The ability to manipulate ideas gives us the machine assisted ability to glean insight from raw text.

Those new to the CI field may not yet know what analytical power they would like to possess as CI managers. The mystique of computers and their software sometimes creates the belief that they can do anything: we need only to be smart enough to use them. This thinking leads us to focus on what they can do, instead of what they could do. And we need more power from our software.

I asked Bill Meade to comment on the problems associated with our use of text management software. Here he shares his views of our analytical limitations and what software vendors should do about it. Glenn S. Omura.
Corporate marketing services
Authors: Galvin Carol
Published: July 2007

Carol Galvin from Digital Equipment Corporation, was the guest speaker at the June 9,1992 meeting of the Boston Chapter. A Marketing Consultant incorporate Marketing Services, she is the focal point for acquisition, management, and dissemination of marketing and competitive information. Corporate Marketing Services (CMS) reports to the Vice President of Corporate Marketing Planning. This column is based on her remarks. Jennifer S. Swanson.
Network security assessment guide
Authors: Brotby W. Krag
Published: July 2007

Electronic data could be your firm's most valuable asset, but information theft and illegal/unethical counterintelligence loom as constant threats. Here is a step‐by‐step guide for performing a security checkup on your computer networks. The process includes physical inspection and interviews with security and information systems personnel. A questionnaire is provided for the inspection and interview process, along with a guide to analyzing and interpreting the results. © 1996 John Wiley & sons. Inc.
Competitive intelligence in china: A case study
Authors: Li Zhengzhong , Dong Yu
Published: July 2007

Competitive intelligence is a new discipline in China, where, despite a booming economy, many aspects of competitive business remain novel. The authors provide a look into how a large, state‐owned enterprise applied CI to adapt to the presence of market competition, providing insight into how Chinese companies appraise the competitive strength of competitors and use this information to create competitive strategies, as well as the emerging role of university academics as business consultants. © 1997 John Wiley & Sons, Inc.
Achat ou téléchargement illégal de la musique chez les consommateurs: Le rôle des réponses à l'artiste et à la musique
Authors: Ouellet Jean‐François
Published: July 2007

Based on qualitative and quantitative surveys, I show that consumer responses toward a particular song and toward its performer(s) play distinct roles in explaining consumer choices to either buy or illegally download that song. The various types of consumer responses to songs and artists are first identified through qualitative research and then validated through exploratory and confirmatory factor analyses (CFA) of survey data. While consumer responses to music explain the need to reexperience and acquire the song, consumer responses to performers explain purchase over illegal downloading. Copyright © 2007 ASAC. Published by John Wiley & Sons, Ltd.
A meta‐analysis and systematic review of the efficacy and safety of anticoagulants as cancer treatment
Authors: Kuderer Nicole M. , Khorana Alok A. , Lyman Gary H. , Francis Charles W.
Published: July 2007

BACKGROUND.

Preclinical evidence suggests that anticoagulants, in particular the low‐molecular‐weight heparins (LMWH), exert an antitumor effect, whereas clinical trials have reported conflicting results. The authors conducted a comprehensive, systematic review and meta‐analysis of the evidence from randomized controlled trials (RCTs), to evaluate the impact of anticoagulants on survival and safety in cancer patients without venous thromboembolism.

METHODS.

A comprehensive systematic literature review of RCTs was performed without language restrictions through May 2006 with subsequent updates to the end of 2006, including an exhaustive search of electronic databases, major conference proceedings, article references, and content experts. Two reviewers extracted data independently. Primary study outcomes were 1‐year overall mortality and all bleeding complications. Major and fatal bleeding complications were secondary outcomes.

RESULTS.

Across all 11 studies that were identified, anticoagulation significantly decreased 1‐year overall mortality with a relative risk (RR) of 0.905 (95% confidence interval [95% CI], 0.847–0.967; P = .003). The RR for mortality was 0.877 (95% CI, 0.789–0.975; P = .015) for LMWH, compared with an RR of 0.942 (95% CI, 0.854–1.040; P = .239) for warfarin, resulting in an absolute risk difference (ARD) of 8% for LMWH and an ARD of 3% for warfarin. Improved survival with anticoagulation may be dependent on tumor type. Major bleeding episodes occurred less frequently in patients who received LMWH (ARD, 1%) compared with patients who received warfarin (ARD, 11.5%; P < .0001). Overall, fatal bleeding occurred rarely (ARD, 0.32%; P = .542).

CONCLUSIONS.

Anticoagulants, particularly LMWH, significantly improved overall survival in cancer patients without venous thrombosis while increasing the risk for bleeding complications. However, given the limitations of available data, the use of anticoagulants as antineoplastic therapy cannot be recommended until additional RCTs confirm these results. Cancer 2007. © 2007 American Cancer Society.
Metastatic patterns at autopsy in patients with ovarian carcinoma
Authors: Güth Uwe , Huang Dorothy Jane , Bauer Gregor , Stieger Marco , Wight Edward , Singer Gad
Published: July 2007

BACKGROUND.

Previously published studies concerning autopsy findings in ovarian cancer failed to consider the broad differences in factors that influence the course of disease. Furthermore, those studies were conducted when the currently accepted standards in diagnostics and therapy had not been fully established. The objective of the current study was to determine the frequency and sites of metastases in patients with ovarian cancer with particular attention to the clinical course and therapy.

METHODS.

Autopsy reports, histologic slides, and clinical files from 197 patients who died of ovarian carcinoma between 1975 and 2005 were studied. The distribution of metastatic sites (19 different organ sites) and metastatic patterns, with particular attention to clinical course (age, length of survival) and therapy (surgical treatment with curative intention, different chemotherapy regimens), were analyzed.

RESULTS.

Overall, 66.3% of patients had metastases to sites outside the abdominopelvic cavity. Patients who were aged >70 years, who had a disease duration ≤6 months, or who had received either no treatment or treatment without curative intention more often had metastases limited to the abdominopelvic cavity. This pattern of spread was observed most frequently in patients who had received current chemotherapy regimens (odds ratio, 3.5; P = .002). Compared with patients who had received chemotherapy according to previous standards, these patients showed a significantly increased incidence of liver metastases (P < .001).

CONCLUSIONS.

Autopsy data may yield important information concerning the metastatic potential of a malignancy and may assist physicians in making clinical management decisions. The results from the current indicated that declining autopsy rates during the last decades have limited the ability of physicians to evaluate the impact of new therapy regimens on the frequency and distribution of metastases through postmortem examination. Cancer 2007. © 2007 American Cancer Society.
An integral‐collocation‐based fictitious‐domain technique for solving elliptic problems
Authors: Mai‐Duy N. , See H. , Tran‐Cong T.
Published: July 2007

This paper presents a new fictitious‐domain technique for numerically solving elliptic second‐order partial differential equations (PDEs) in complex geometries. The proposed technique is based on the use of integral‐collocation schemes and Chebyshev polynomials. The boundary conditions on the actual boundary are implemented by means of integration constants. The method works for both Dirichlet and Neumann boundary conditions. Several test problems are considered to verify the technique. Numerical results show that the present method yields spectral accuracy for smooth (analytic) problems. Copyright © 2007 John Wiley & Sons, Ltd.
An analysis on short‐term frequency stability of an optically pumped cesium beam frequency standard: Laser noise influence
Authors: Hisadome Kenji , Kihara Masami
Published: July 2007

To overcome various problems in cesium beam resonators using polarized magnetic fields, researches on cesium beam resonators with optical pumping are being carried out. In these optically pumped cesium beam resonators, the frequency fluctuations of the laser diode (LD) used to excite the cesium beam affects the frequency stability of the resonator.

This paper proposes a method in which the frequency fluctuations of the laser light are reduced to the noise induced on the control loop of the resonator. In this method, the absorption line of the cesium beam is used as the light standard frequency and the frequency fluctuations of the stabilized LD is determined. Further, such frequency‐stabilized LD is used in an optically pumped cesium beam resonator and its short‐term frequency stability is analyzed. As a result, it is shown that high‐frequency stability s̀yo(γ) < 10−13/τ is achievable while the cesium beam intensity and absorption linewidth remain the same as those of present small resonators.
Design of drain junction in polysilicon MOSFETs
Authors: Hayashi Hisao
Published: July 2007

It has been reported that when polycrystalline silicon is used for the active layer in an MOS transistor, the breakdown voltage in the drain junction is low and the junction leakage current is high.

In this paper, the behavior of the drain junction was analyzed and the optimum design was carried out. It was found that in the drain junction, the current generated at the Si‐SiO2 interface predominates when the electric field is low and the tunnel current predominates when the field exceeds 2 × 105 V/cm.

To improve the junction characteristic without degradation of the transistor driving efficiency, a high‐resistance drain was used. As a result, it was found that the optimum resistance was 5 to 100 kohm/sq. To control this resistance, it is important to minimize the local state density. To achieve this goal, the polycrystalline silicon should be 10 to 50 nm thick. The solid‐phase growth technique is effective in improving the crystallinity.

This paper will show that it is possible to design a polycrystalline silicon transistor with high breakdown voltage, low leakage current, and high mutual conductance.
The correction procedure for “packaged‐type transistor” s‐parameter measurements (∼1 GHz)
Authors: Aoki Hitoshi
Published: July 2007

In the measurement of transistor S‐parameters, an automatic network analyzer presently is used in which the matching of the measurement system and the directivity including the measurement jigs are calibrated accurately by means of the twelve‐term calibration functions contained in the analyzer. However, when a packaged transistor is measured, the parasitic capacitance, lead inductance and resistance are contained. The author developed a simple procedure for modeling these parasitic elements and removing them by means only of subtraction from the mutual transformation of S→Y→Z parameters. Experiments were carried out with an HP8753 Network Analyzer and TECAP model parameter extraction software [1] and the results were compared with those by the SPICE simulation. Good agreement was obtained in the frequency vs. gain characteristics up to 1 GHz. It is now possible to obtain data very close to those of only the transistor portion.
Analysis on waveguiding property of GaAs‐AlGaAs MQW nonlinear optical waveguide
Authors: Ohke Shigeaki , Umeda Tokuo , Cho Yoshio
Published: July 2007

This paper investigates the characteristics of a nonlinear optical waveguide using the nonlinear index of refraction caused by room‐temperature excitons in a multiple quantum well (MQW) structure. In the case where the MQW structure is used as a core, the MQW structure mentioned is considered as a single‐layer nonlinear medium so that the entire structure is modeled as a three‐layer slab waveguide. Further, the eigenmode expansion approach is applied to infinitesimal sections along the direction of propagation. Numerical analysis is carried out by this infinitesimal section eigenmode expansion technique. The change of the index of refraction accompanying the room‐temperature exciton absorption line can take a positive or negative sign by detuning (of the frequency). When the optical propagation characteristics for both the positive and negative detunings are analyzed, it is found that the power trapping and power dissipation caused by the nonlinear effect occur significantly after a propagation within about one millimeter.
Waveguide band rejection filter using yttrium iron garnet films
Authors: Okubo Kensuke , Tsutsumi Makoto
Published: July 2007

This paper describes the theoretical and experimental characteristics of the band reject filter made of a waveguide loaded with yttrium‐iron‐garnet (YIG) films. First, the problem of reflection and transmission of the plane electromagnetic wave from a semiinfinite YIG film is described. Next, it is noted that the electromagnetic wave of the TE10 mode in a waveguide loaded with an isotropic medium can be expressed as a superposition of these plane waves. Their treatment is applied in an approximate approach to the waveguide loaded with a YIG film. The band rejection characteristics are investigated in which the center frequency varies depending on the dc magnetic field applied. Further, it is shown that a good characteristic is obtained as a band reject filter if YIG films are stacked as a multilayer.

Finally, an experiment is carried out at the × band so that the forementioned characteristics are confirmed experimentally. When a dc magnetic field of 2.818 kOe is applied, the observed filter characteristics are such that the center frequency is 10.0 GHz, the insertion loss is 1.0 dB, the bandwidth is 144.7 MHz and the maximum attenuation within the stopband exceeds 60 dB.
Improvement of adhesion to sin thin film on the polycarbonate substrate
Authors: Takahashi Shigeru , Sato Toshiya , Fukuda Takuya , Ohue Michio
Published: July 2007

Low‐temperature microwave plasma CVD deposition of an SiN film on a polycarbonate substrate for a photomagnetic disc was attempted. To enhance the adhesion between the SiN film and polycarbonate substrate, an Si intermediate film was deposited by plasma CVD.

As a result, it was found that a peel‐free and crack‐free substrate could be fabricated by depositing an Si intermediate layer by (microwave + RF) superimposed CVD.

To investigate the high adhesion of the Si film to the substrate, the concentration of elements at the interface was analyzed by RBS (Rutherford backscaering spectrometry). As a result, it was confirmed that not only an Si intermediate layer but also a complex film consisting of polycarbonate and Si is present near the surface of the polycarbonate substrate. It was concluded that the improvement of the film adhesion was due to the chemical bond between polycarbonate and Si.
Finite‐element analysis of ferrite disk resonators by introducing field‐assigned points
Authors: Yoneda Naofumi , Yoneyama Tsukasa
Published: July 2007

In this paper, resonant frequencies are calculated by the method of finite elements for resonators with anisotropic ferrite disks. The finite‐element methods with three electric field components are used in general for analyses of ferrite resonators with tensor permeabilities. A new treatment becomes necessary for boundary conditions of the electric fields at the edges of ferrite resonators. By introducing field‐assigned points at resonator edges, it is possible to calculate resonant frequencies.

To examine calculated results, the resonant frequencies of resonators with isotropic circular disks were compared. Then the obtained results are compared with calculated results by other methods. It is noted that the authors' method possesses a high level of calculation precision. As a practical example, the resonant frequencies of anisotropic disk resonators loaded inside a below‐cutoff parallel plate waveguide are calculated. Experimentally measured data and the authors' calculated results have been confirmed to show good agreement.
A method of analysis for a circuit consisting of multistage connection of tapered waveguides
Authors: Ishihara Fujio , Suga Takashi , Iiguchi Shinichi
Published: July 2007

A general‐purpose analysis method is described for a tapered waveguide circuit made of a cascade of several tapered sections. It is assumed that the thermal loss can be neglected and the tapers are smooth so that no consideration of multiple modes is needed. First, in each tapered section, the differential equation describing the electromagnetic field of the mode of interest is derived. By solving this equation, the F matrix is obtained. By multiplying all F matrices, that of the entire structure is obtained. The elements of the F matrix are transformed to the reflection coefficient. As an example, a circuit made of four tapered waveguides and three uniform waveguides is computed numerically. It is confirmed that the results agree well with experimental results. Also presented is a computer program.

The unique feature of the present method is that in spite of its simplicity it enables analysis beyond and before cutoff with similar accuracy. The method also enables analysis without cumbersome procedures even if the taper shape is represented by various curves and the number of stages of tapered waveguides is increased.
Properties of cutoff filters using raised cosine impedance tapered waveguides of varying heights
Authors: Shirasaki Hirokimi
Published: July 2007

When the height of a tapered waveguide with its characteristic impedance changing in an n‐th power cosine profile with a varying cutoff frequency is varied, a resonance occurs near the cutoff frequency. In anticipation of improved rising properties of the insertion loss and the return loss, the reflection and transmission coefficients of the cutoff filter are derived. These coefficients are obtained numerically by solving the Runge‐Kutta method in which the differential equation valid for the rectangular TE10 mode in a tapered waveguide satisfies the boundary conditions at the waveguide junctions.

Next, the characteristics of the filter are analyzed by introducing a shape factor which indicates the rising property of a single taper near the cutoff frequency. Property charts are developed which can be used for deriving a small and high‐performance taper shape satisfying the requirements as a high‐pass filter. It is demonstrated that a small size and high performance can be realized by varying the height.
An analysis of wave propagation in linearly tapered dielectric slab waveguides considering reflected waves
Authors: Kodama Masao
Published: July 2007

The beam propagation method proposed by Feit and Fleck is a powerful method for analyzing optical circuits. However, in this method, only the incident wave in the circuit is assumed and the Helmholtz equation is replaced with an approximate equation. Hence, it is not possible to compute the magnitude of the reflected wave. Even in the absence of the reflected wave, it is not possible to compute the incident wave accurately.

To improve these deficiencies, this paper uses the Helmholtz equation directly instead of modifying it to an approximate form. The problem of instability is resolved by a certain restriction on the solution. Therefore, the reflected wave can also be analyzed with the incident wave.

The method in this paper provides a solution more accurate than the conventional beam propagation method, even if there is no reflected wave present. The present method is applied to a tapered section of a dielectric slab waveguide and the radiation loss and the magnitude of the reflected wave are obtained numerically. It is shown that the magnitude of the reflected wave is negligibly small. The accuracy of the solution by the present method is discussed.
Sensors by micromachining
Authors: Esashi Masayoshi
Published: July 2007

Photofabrication developed for integrated circuits can be used to fabricate sensors with three‐dimensional structures and devices with many other types of structures. The micromachining technology is useful in forming a small‐sized, high‐performance sensor system. Using this technology, it is possible to form a system with a sensor, actuator, and electronic circuit on a silicon wafer.

A thermo‐flow sensor was fabricated with two microheaters to detect small gas flow. It was found that this device was sensitive to detect an extremely low gas flow with high linearity. This flow sensor was used for an integrated mass‐flow controller and as an integrated magnetic oxygen sensor.

An integrated capacitive pressure sensor also was developed with a capacitive detection circuit. The new feed‐through structure used for this sensor was used for other integrated sensors such as a tactile imager.