bluuebunny/crossref_metadata_2025 huggingface dataset:
Direkte Festphasen‐Glycosylierung von Peptiden an einem neuartigen Polyethylenglycol‐Harz
Authors: Schleyer Axel , Meldal Morten , Renil M. , Paulsen Hans , Bock Klaus
Published: July 2007

Glycopeptid‐Bibliotheken, bei denen sowohl der Kohlenhydrat‐ als auch der Peptidteil variiert werden, können durch die stereoselektive Glycosylierung freier Hydroxygruppen von festphasengebundenen Peptiden mit Glycosyltrichloracetimidaten hergestellt werden. Unter Nutzung von temporären tBu‐Schutzfunktionen gelang so die stereoselektive Synthese einer Bibliothek aus vier Glycopeptiden (eines ist rechts dargestellt) mit je zwei unterschiedlichen Glycosylgruppen.

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[NH4]3[Ir(S4)(S6)2]: eine erneute Untersuchung des 1904 von Hofmann und Höchtlen beschriebenen [NH4]3[Ir(S5)3]
Authors: Albrecht‐Schmitt Thomas E. , Ibers James A.
Published: July 2007

Nicht 15, sondern 16 Schwefelatome enthält das 1904 erstmals als „[NH4]3[IrS15]”︁ beschriebene Komplexsalz [NH4]3[Ir(S4)(S6)2]. Dies folgt aus dem Vergleich der Ergebnisse einer Kristallstrukturanalyse (Strukturbild des Anions rechts) und der Beschreibung des Kristallhabitus in der Originalarbeit. Während der Kristallisation von [NH4]3[Ir(S4)(S6)2] tritt spontane Racematspaltung auf. Ein Jahrzehnt vor Werners erstmaliger Trennung optisch aktiver anorganischer Komplexe waren also bereits enantiomerenreine Kristalle verfügbar.

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Boratabenzol‐Zirconium(II)‐Komplexe: eine ungewöhnliche Anellierung mit Ethinen
Authors: Ashe Arthur J. , Al‐Ahmad Saleem , Kampf Jeff W. , Young Victor G.
Published: July 2007

Gefaltet ist der Boratanaphthalinligand in 2, so daß die Abstände aller zehn Ringatome zum Metallzentrum in der Größenordnung von Zr‐C‐bzw. Zr‐B‐Bindungslängen liegen. 2 wurde durch eine neuartige Reaktion von Acetyln mit einem der Boratabenzolliganden von 1 erhalten.

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Gezielt entworfene Epothilone: kombinatorische Synthese, Induktion der Tubulin‐Polymerisation und cytotoxische Wirkung gegen taxolresistente Tumorzellen
Authors: Nicolaou Kyriacos Costa , Vourloumis Dionisios , Li Tianhu , Pastor Joaquin , Winssinger Nicolas , He Yun , Ninkovic Sacha , Sarabia Francisco , Vallberg Hans , Roschanger Frank , King N. Paul , Finlay M. Ray V. , Giannakakou Pareskevi , Verdier‐Pinard Pascal , Hamel Ernest
Published: July 2007

Eine Bibliothek von Epothilon‐A und ‐B‐Analoga, die durch kombinatorische Festphasensynthese mit SMART‐Mikroreaktoren sowie durch konventionelle Chemie in Lösung hergestellt wurde, wurde in zwei unterschiedlichen Tubulin‐Bindungs‐Assays untersucht. Ausgewählte Verbindungen wurden darüber hinaus hinsichtlich ihrer Cytotoxizität gegen mehrere Krebszellinien, einschließlich taxolresistenter, bewertet. Daraus wurden wichtige Struktur‐Wirkungs‐Beziehungen gewonnen, die den Weg für weitere Entdeckungen und Entwicklungen auf dem Gebiet der Krebsforschung ebnen werden.
Tetra‐tert‐butyltetraboran(6) B4H2tBu4 ‐ ein Derivat aus der Reihe BnHn+2
Authors: Neu Andreas , Mennekes Theo , Englert Ulli , Paetzold Peter , Hofmann Matthias , Schleyer Paul Von Ragué
Published: July 2007

Aus RBBr2 und Na/K‐Legierung erhält man ebenso wie zweistufig aus B4R4 und Na/K‐Legierung und nachfolgender Einwirkung von HCl das Tetraboran B4H2R4 (R = tBu). Aus NMR‐Daten und einer ab‐initio‐Rechnung für die Stammverbindung B4H6 sowie für B4H2Me4 läßt sich eine B4‐Tetraederstruktur 1 ableiten, in der zwei gegenüberliegende Kanten durch je ein H‐Atom überbrückt sind (D2d‐Symmetrie). Im Tetraboran B4H2R4 kann man mit Lithium in Tetrahydropyran (L) ein Brücken‐H‐Atom gegen die Gruppierung LiL2 austauschen. (L2Li)B4HR4 wurde durch Einkristall‐Röntgenstrukturanalyse charakterisiert.

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N‐Heterocyclische Carbene
Authors: Herrmann Wolfgang A. , Köcher Christian
Published: July 2007

Lange Zeit war die Chemie der N‐heterocyclischen Carbene auf Koordinationsverbindungen beschränkt, die aus Azoliumsalz‐Vorstufen synthetisiert werden können, wie es Wanzlick und Öfele 1968 zum ersten Mal beschrieben hatten. Seit aber durch die Arbeiten von Arduengo (1991) freie Carbene zur Verfügung stehen, erlebt dieses bisher wenig beachtete Gebiet eine anhaltende Renaissance. Ein Leitmotiv sind dabei die vorteilhaften Eigenschaften der N‐heterocyclischen Carbene als Liganden in der metallorganischen Katalyse, wo sie die breite Anwendungspalette der Phosphane ergänzen und erweitern. Hier wird der gegenwärtige Wissensstand auf dem Gebiet der Synthese‐ und Strukturchemie, der Bindungstheorie, Koordinationschemie und Katalyse zusammengefaßt. Chelatisierende, funktionalisierte, chirale und immobilisierte Liganden können in einfachen Verfahren unter milden Bedingungen hergestellt und an Metallzentren fixiert werden, wodurch sich ein neues, weites Feld der Chemie eröffnet. Auch die Rolle der von Imidazol und Triazol abgeleiteten Carbene als Liganden in der Katalyse wird in dieser Übersicht beleuchtet. Es wäre denkbar, daß N‐heterocyclische Carbene die allgegenwärtigen Phosphane in manchen metallorganisch katalysierten Reaktionen als Liganden ersetzen.
Anaerobe Kupfer‐katalysierte Oxidation von Alkoholen zu Aldehyden und Ketonen
Authors: Markó István E. , Tsukazaki Masao , Giles Paul R. , Brown Stephen M. , Urch Christopher J.
Published: July 2007

Auch unter Ausschluß von Sauerstoff funktioniert die Kupfer‐katalysierte Oxidation von Alkoholen wie 1 [Gl. (1)], die zuvor unter aeroben Bedingungen durchgeführt worden ist. Nichtbenzylische und sekundäre Alkohole sind ebenfalls geeignete Substrate. Eine Schlüsselrolle nehmen dabei die Azodicarboxylate ein: Sie dienen nicht nur als Komplexliganden, sondern auch als Hydridacceptoren, wobei sperrige Reste R besonders günstig sind.

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Ladungstransport in DNA: eine Kontroverse
Authors: Diederichsen Ulf
Published: July 2007

Der Elektronentransfer über Entfernungen von über 40 Å entlang eines DNA‐Doppelstranges (siehe schematische Darstellung rechts) bleibt mechanistisch umstritten, scheint aber als experimenteller Befund gesichert zu sein. Biochemische Vorgänge wie die Reparatur eines Photodimerschadens können durch DNA‐Elektronentransfer ausgelöst werden. Die Abhängigkeit der Elektronentransportfähigkeit von der Perfektion eines DNA‐Basenstapels legt nahe, die Leitfähigkeit als Maß der Basenstapelungsqualität oder zur Erkennung einer DNA‐Einzelstrangsequenz zu verwenden.

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Synthese, Struktur und Koordinationschemie von Diisocyanmethan
Authors: Buschmann Jürgen , Bartolmäs Thilo , Lentz Dieter , Luger Peter , Neubert Ingo , Röttger Matthias
Published: July 2007

Selbst in Lösung wenig beständig ist das seit über 30 Jahren bekannte Diisocyanmethan. Nun gelang die Isolierung dieses bis jetzt einzigen geminalen Isocyanids (Struktur im Kristall siehe rechts) durch fraktionierende Kondensation. Die Verbindung kann durch Koordination an Übergangsmetallatome stabilisiert werden.

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Synthese, Struktur und Reaktivität von Zirconium(IV)‐Komplexen mit Tropidinylliganden
Authors: Lavoie Gino G. , Bergman Robert G.
Published: July 2007

Isoelektronisch zum Cyclopentadienyl‐Liganden, aber weniger symmetrisch ist der Tropidinyl(trop)‐Ligand. So sind die beiden Liganden in den stabilen Komplexen [(trop)2‐ZrCl2] 1 und [(trop)2ZrMe2] um 77 bzw. 88° gegeneinander gedreht. Erst Untersuchungen ergaben unter anderem, daß 1 die Polymerisation von Ethylen katalysiert.

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Ligandengestützte Kopplung metallorganischer Reaktionszentren
Authors: Kaim Wolfgang , Reinhardt Ralf , Fiedler Jan
Published: July 2007

Elektronenreservoir‐Verhalten, die Bildung gemischtvalenter RhII/RhI‐Spezies und die Aufspaltung der Redoxprozesse durch “Kommunikation” zwischen den Redoxzentren wurden bei der ersten systematischen Untersuchung zur ligandengestützten Kopplung zweier äquivalenter Redox‐(ECE)‐Reaktionszentren festgestellt (siehe Schema rechts; E = Elektronentransfer; C = chemischer Schritt, hier die Chloridabspaltung; Cp* = C5Me5; L = mehrzähniger Ligand).

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Platinkatalysierte regioselektive Silaborierung von Alkenen
Authors: Suginome Michinori , Nakamura Hiroshi , Ito Yoshihiko
Published: July 2007

2‐Boryl‐1‐silylalkane entstehen regioselektiv bei der hier vorgestellten Addition einer B‐Si‐Bindung an die C‐C‐Doppelbindung einfacher terminaler Alkene [G1. (1)]. Als Katalysatoren eignen sich (Triphenylphosphan)platinkomplexe. An der B‐C‐Bindung ist eine Homologisierung um ein C‐Atom möglich.

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Rastertunnelmikroskopische Beobachtung der Monoschicht eines Diacetylenderivats auf Graphit vor und nach der Polymerisation mit submolekularer Auflösung
Authors: Grim Petrus C. M. , De Feyter Steven , Gesquière André , Vanoppen Peter , Rücker Markus , De Schryver Frans C. , Valiyaveettil Suresh , Moessner Georg , Müllen Klaus
Published: July 2007

Die Photopolymerisation einer an Graphit physisorbierten Monoschicht eines Diacetylenderivats, das eine Isophthalsäure‐Kopfgruppe und einen Decylrest als unpolaren Schwanz enthält, wurde durch Rastertunnelmikroskopie (STM) unter‐sucht. Rechts ist ein submolekular aufgelöstes STM‐Bild einer Domänengrenze zu sehen, die eine unpolymerisierte Monoschicht (untere Domäne) von einer polymerisierten (obere Domäne) trennt.

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Nachweis skalarer 6Li, 15N‐Kopplungen über koordinative Li‐N‐Bindungen
Authors: Hüls Dietmar , Günther Harald , Van Koten Gerard , Wijkens Peter , Jastrzebski Johann T. B. H.
Published: July 2007

Bei natürlichem 15N‐Gehalt der Probe wurden bei der im Festkörper und in Lösung tetrameren Organolithiumverbindung 1 6Li, 15N‐Spin‐Spin‐Kopplungen über koordinative Li‐N‐Bindungen nachgewiesen. Die Kopplungskonstanten von 3.6 und 4.2 Hz korrelieren mit den aus der Kristallstrukturanalyse erhaltenen Li‐N‐Abständen.

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Durch Rasterkraftmikroskopie atomar aufgelöste Struktur an den Bruchflächen eines Ba/Si/O/C‐Glases
Authors: Lansmann Volker , Jansen Martin , Raberg Wolfgang , Wandelt Klaus
Published: July 2007

Keine periodischen Strukturen treten der topographischen Rasterkraftmikroskopie‐Direktabbildung (siehe rechts) zufolge in der Bruchfläche eines Ba/Si/O/C‐Glases auf. Die vorgestellten Ergebnisse verdeutlichen das enorme Potential der noch jungen Methode zur Ermittlung von charakteristischen Strukturelementen in Festkörpern ohne Translationssymmetrie.

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Ba2Nd7Si11N23 — ein Nitridosilicat mit zeolithartiger Si‐N‐Gerüststruktur
Authors: Huppertz Hubert , Schnick Wolfgang
Published: July 2007

Die neue Substanzklasse der Nitridozeolithe wird erschlossen durch den formalen Austausch von Sauerstoff gegen Stickstoff in mikroporösen Oxozeolithen. Ba2Nd7Si11N23 ist das erste Beispiel mit einer von großen Kanälen durchzogenen Gerüststruktur aus eckenverknüpften SiN4‐Tetraedern. Im krassen Gegensatz zu konventionellen oxidischen Zeolithen ist dieser Nitridozeolith bis 1600°C stabil.

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Darstellung und Struktur von [Cd10Se4(SePh)12(PPh3)4] und [Cd16(SePh)32(PPh3)2]
Authors: Behrens Silke , Bettenhausen Marco , Eichhöfer Andreas , Fenske Dieter
Published: July 2007

Cluster mit und ohne Hohlraum entstehen bei der Umsetzung von [CdCl2(PPh3)2] mit PhSeSiMe3. Je nach verwendetem organischem Lösungsmittel kristallisieren die Verbindungen [Cd10Se4(SePh)12(PPh3)4] und [Cd16(SePh)32(PPh3)2] (im Bild rechts gezeigt; der Cluster ist nahezu vollständig von Phenylringen bedeckt), die aus verknüpften adamantanartigen Cd‐Se‐Käfigen aufgebaut sind.

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Zylindrische molekulare Bürsten
Authors: Dziezok Peter , Fischer Karl , Schmidt Manfred , Sheiko Sergei S. , Möller Martin
Published: July 2007

Ein zweidimensionales Labyrinth wird durch Selbstorganisation zylindrischer, bürstenförmiger Polymakromonomere auf Glimmer erhalten. Rasterkraftmikroskopisch konnten einzelne “Bürstenmoleküle” innerhalb einer Monolage aufgelöst werden (siehe rechts). Dies ist der erste Schritt zur Herstellung definierter, strukturierter Oberflächen im Nanometerbereich mit molekularer Auflösung.

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Ein neuartiger Zugang zum zentralen Gerüst von CP‐225,917 und CP‐263,114
Authors: Nicolaou Kyriacos C. , Postema Maarten H. D. , Miller Neil D. , Yang Guang
Published: July 2007

Die Rh‐katalysierte Bildung eines Carbens und dessen intramolekulare Abfangreaktion, gefolgt von einer Divinylcyclopropan‐Umlagerung und einer radikalischen Cyclisierung sind die wesentlichen Reaktionen einer neuen Strategie zum Aufbau des Bicyclo[4.3.1]dec‐1(9),4‐dien‐10‐on‐Gerüstes der im Titel genannten Naturstoffe. Das Gerüst der erhaltenen Modellverbindung 1 unterscheidet sich hiervon lediglich hinsichtlich der Konfiguration am quartären Zentrum.

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Enantioselektive Synthese von Altohyrtin C (Spongistatin 2): Synthese der AB‐ und CD‐Spiroketale
Authors: Evans David A. , Coleman Paul J. , Dias Luiz Carlos
Published: July 2007

Die erste Totalsynthese eines Spongipyran‐Makrolids, des Altohyrtins C (Spongistatin 2; siehe unten), wurde erfolgreich abgeschlossen. Die aus Meeresschwämmen isolierten Spongipyrane gehören zu den stärksten cytotoxischen Verbindungen und wirken gegen mehrere menschliche Krebszellinien. Während die vorgeschlagenen Strukturen für die unabhängig isolierten Altohyrtine und Spongistatine im wesentlichen gleich sind, unterscheiden sie sich in der relativen Konfiguration der Untereinheiten. Durch die Totalsynthese wurde nun die vorgeschlagene Struktur der Altohyrtine bestätigt und nachgewiesen, daß Altohyrtin C und Spongistatin 2 identisch sind.

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Measuring the relative interface thickness of multilayer polyolefin films with atomic force microscopy
Authors: Paradkar Rajesh P. , Li Jing , Bar Georg , Pham Hoang , Bosnyak Clive , Weinhold Jeffrey
Published: July 2007

In any polymer blend system, the nature and thickness of the polymer interface can have a significant influence on the overall performance of the blend. Consequently, it is important to understand the nature of the interactions between the various blend components to effectively design blend combinations with desired end‐use properties. However, because of the inherent level of difficulty, the quantitative measurement of the interface thickness in immiscible polymer blends has not been accomplished or reported in the literature. Atomic force microscopy in the tapping mode has been employed to establish a systematic methodology to measure the relative interface thickness of seven types of coextruded multilayer polyolefin films. Criteria have been developed to define profiles of the interface and estimate the interface thickness from these profiles. The effects of tip indentation on the measured value of the interface thickness are also considered. The atomic force microscopy method presented here allows for a direct quantitative estimate of the interface thickness in multilayer polyolefin films, which in turn provides a significantly better understanding of physical properties such as tear in coextruded blown films and the toughness/stiffness balance in injection‐molded impact copolymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Ring‐Rearrangement Metathesis
Authors: Holub Nicole , Blechert Siegfried
Published: July 2007

Ring‐rearrangement metathesis (RRM) refers to the combination of several metathesis transformations into a domino process, in which an endocyclic double bond of a cycloolefin reacts with an exocyclic alkene. RRM has proven to be a powerful method for the rapid construction of complex structures. The extension of the basic ring‐opening–ring‐closing metathesis process by further metathesis steps as well as an examination of the driving forces, limits, scope, recent advantages, and future perspectives of these domino sequences is presented with various examples, thus reflecting the high efficiency and utility of RRM in organic synthesis.
Systematic review of foam sclerotherapy for varicose veins
Authors: Jia X , Mowatt G , Burr J M , Cassar K , Cook J , Fraser C
Published: July 2007

Background and method

Foam sclerotherapy is a potential treatment for varicose veins. A systematic review was undertaken to assess its safety and efficacy.

Results

Sixty-nine studies were included. The median rates of serious adverse events, including pulmonary embolism and deep vein thrombosis, were less than 1 per cent. The median rate of visual disturbance was 1·4 per cent, headache 4·2 per cent, thrombophlebitis 4·7 per cent, matting/skin staining/pigmentation 17·8 per cent and pain at the site of injection 25·6 per cent. The median rate of complete occlusion of treated veins was 87·0 per cent and for recurrence or development of new veins it was 8·1 per cent. Meta-analysis for complete occlusion suggests that foam sclerotherapy is less effective than surgery (relative risk (RR) 0·86 (95 per cent confidence interval (c.i.) 0·67 to 1·10)) but more effective than liquid sclerotherapy (RR 1·39 (95 per cent c.i. 0·91 to 2·11)), although there was substantial heterogeneity between studies.

Conclusion

Serious adverse events associated with foam sclerotherapy are rare. There is insufficient evidence to allow a meaningful comparison of the effectiveness of this treatment with that of other minimally invasive therapies or surgery.
Randomized clinical trial examining the effect of music therapy in stress response to day surgery
Authors: Leardi S , Pietroletti R , Angeloni G , Necozione S , Ranalletta G , Del Gusto B
Published: July 2007

Background

Music therapy could reduce stress and the stress response. The aim of this study was to investigate the role of music therapy in alleviating stress during day surgery.

Methods

Sixty patients undergoing day surgery were randomized to one of three groups, each containing 20 patients. Before and during surgery, patients in group 1 listened to new age music and those in group 2 listened to a choice of music from one of four styles. Patients in group 3 (control group) heard the normal sounds of the operating theatre. Plasma levels of cortisol and subpopulations of lymphocytes were evaluated before, during and after operation.

Results

Plasma cortisol levels decreased during operation in both groups of patients who listened to music, but increased in the control group. Postoperative cortisol levels were significantly higher in group 1 than in group 2 (mean(s.d.) 14·21(6·96) versus 8·63(2·72) ng/dl respectively; P < 0·050). Levels of natural killer lymphocytes decreased during surgery in groups 1 and 2, but increased in controls. Intraoperative levels of natural killer cells were significantly lower in group 1 than in group 3 (mean(s.d.) 212·2(89·3) versus 329·1(167·8) cells/µl; P < 0·050).

Conclusion

Perioperative music therapy changed the neurohormonal and immune stress response to day surgery, especially when the type of music was selected by the patient.
On a personal note
Authors: Carver John
Published: July 2007

I am indebted to those organizations that submitted mission statements in response to my requests in Issues 2 and 3. Thanks for bravely allowing your work to be examined according to the principles of the Policy Governance model. Space does not allow me to use all the mission statements sent in. For statements I received before December 1, I have commented directly to those who responded
Implementing policy governance the slow way
Authors: Mitchell Brian
Published: July 2007

IN 1989, the Edmonton (Alberta) Catholic School Division—a publicly funded Catholic school division—began a slow and painstaking process of implementing Policy Governance. Though all involved were aware that in principle Policy Governance is best implemented quickly and completely, this board, which had been in existence for 110 years, needed more time. Finally, in 1997, the switch was completed. Where did the board find the discipline to keep moving toward Policy Governance? Brian Mitchell, who has been on the board since 1992, explains it was part necessity, part patience, and part dedication to pursuing the board's mission. The division's ends policies appear in the sidebar on page 2.
Finding unity and strength through board diversity
Authors: Tremaine Leslie
Published: July 2007

When Louisiana's Jefferson Parish Human Services Authority was first created nine years ago, its board was made up of a fairly traditional group of people—the kind, says executive director Leslie Tremaine. who “typically get named by folks to do things like this.” But in the intervening years the makeup of the board changed considerably so that it is now truly diverse. This change didn't happen on its own; it took a conscious effort on the part of the board. Tremaine describes how the group went about achieving board diversity and how this diversity is making a difference.
Profile of a board member
Authors: Engle Steve , Andrews Jerome
Published: July 2007

Steve Engle and Jerome Andrews of the Associated Locksmiths of America (ALOA) present here a profile they devised to instruct their board's nominating committee when seeking new members. In commenting on their purpose in developing this profile, Engle and Andrews observed, “Board members are trustees for the membership and consequently must bear initial responsibility for the integrity of governance. The board is responsible for its own development, its own job design, its own discipline, and its own performance”.

Further, they said, and the board agreed, that “in order to recruit quality members to the ALOA board of directors, the board should be sure to let candidates know before they come on the board that the system used is Policy Governance. We must let our prospective new members know how the board sees the job of governance. They can then make an informed choice about their willingness to serve”.
Policy governance demands that we choose our words carefully
Authors: Davis Gary
Published: July 2007

Gary Davis is a Policy Governance consultant who regularly participates in the Policy Governance Forum on the Web site www.carvergovernance.com. Pursuant to a dialogue he conducted with another participant on the topic of language, we asked him to write this article.
Surviving the transition: Reigniting the passion
Authors: Loucks Randee
Published: July 2007

When new members join a Policy Governance board, it is imperative that they be thoroughly oriented to the theory and practice of the model. Well‐planned orientation not only ensures that new members will be stewards of good governance but also helps veteran members revitalize their own commitment to the model. In this article, Randee Loucks breaks down, orientation into a logical five‐step process.
Policy governance as a value investment: Succession planning
Authors: Moore Jannice
Published: July 2007

Implementing Policy Governance requires a significant investment of time, effort, and money. This is the first of several articles that will examine behaviors of boards that invest wisely in Policy Governance. How can they be sure to make a “value investment” that will stand the test of time, rather than a “day trade” with possible short‐term gain but not necessarily substantive gain in the long run? Based on her experience with a variety of boards that have implemented the model, Jannice Moore shares some of the conditions and behaviors that contribute to value investing. In this article, she considers the importance of succession planning. Future articles will consider the role of good information and planning in making Policy Governance a value investment.
Means, ends, and ideals
Authors: Carver John
Published: July 2007

In this article, John Carver considers the ends policies of a women's center. He finds an unusually well conceived ends statement but also uncovers a common error in the crafting of mega‐ends policies. Like so many other organizations, this one appears to have committed itself to an end so ambitious as to be practically unattainable. The article shows that it is important to distinguish between a vision of a better world that motivates a board and a result that a board can realistically commit its organization to accomplish in the world.
Value investing: A governance action plan
Authors: Moore Jannice
Published: July 2007

Implementing Folicy Governance involves a significant investment of time, effort, and money. This is the second of several articles that will examine behaviors of boards that invest wisely in Policy Governance. How can they be sure to make a “value investment” that will stand the test of time, rather than a “day trade” with possible short‐term gain but not necessarily substantive gain in the long run? Based on her experience with a variety of boards that have implemented the model, Jannice Moore shares some of the conditions and behaviors that contribute to value investing. In Issue 60 of Board Leadership, she discussed succession planning, orientation for prospective and new board members, length of tenure, and the need to be committed to the principles of the model, even when the goinggets rough. In this article, she introduces the idea of a Governance Action Plan (GAP). A GAP is not the establishment of ends policies but rather a tool that boards can use to set realistic objectives for themselves and to monitor their own progress in their implementation of Policy Governance.
Policy governance and other governance models compared
Authors: Oliver Caroline
Published: July 2007

Many observers would say that Policy Governance is the first “governance model,” but boards are presented with a range of other options. In this article, Caroline Oliver gives an overview of those other options. What are they? How do they function? Are they really models, or are they merely descriptions of some common board arrangements? What are their relative advantages and disadvantages? And most important, are they likely to foster good governance?
Design, Synthesis, and Antifungal Activities of Novel 1H‐Triazole Derivatives Based on the Structure of the Active Site of Fungal Lanosterol 14α‐Demethylase (CYP51)
Authors: Zhao Qing‐Jie , Hu Hong‐Gang , Li Yao‐Wu , Song Yan , Cai Ling‐Zhi , Wu Qiu‐Ye , Jiang Yuan‐Ying
Published: July 2007

A series of fluconazole (1) analogues, compounds 3a–k, were prepared as potential antifungal agents. They were designed by computational docking experiments to the active site of the cytochrome P450 14α‐sterol demethylase (CYP51), whose crystal structure is known. Preliminary biological tests showed that most of the target compounds exhibit significant activities against the eight most‐common pathogenic fungi. Thereby, the most potent congener, 1‐[(4‐tert‐butylbenzyl)(cyclopropyl)amino]‐2‐(2,4‐difluorophenyl)‐3‐(1H‐1,2,4‐triazol‐1‐yl)propan‐2‐ol (3j), was found to exhibit a broad antifungal spectrum, being more active against Candida albicans, Candida tropicalis, Cryptococcus neoformans, Microsporum canis, and Trichophyton rubrum (MIC80<0.125 μg/ml) than the standard clinical drug itraconazole (2). The observed affinities of the lead molecules towards CYP51 indicate that a cyclopropyl residue enhances binding to the target enzyme. Our results may provide some guidance for the development of novel triazole‐based antifungal lead structures.
Antibacterial Effects of a Monoporphyrinato Ytterbium(III) Complex and Its Free Components on Staphylococcus aureus as Determined by Stop‐Flow Microcalorimetry
Authors: Hou An‐Xin , Xue Zhi , Liu Yi , Qu Song‐Sheng , Wong Wai‐Kwok
Published: July 2007

The antibacterial effect of Yb3+, the free porphyrin base 5,10,15,20‐tetrakis(4‐methoxyphenyl)porphyrin (H2TMP; 1), and the corresponding Yb3+ porphyrinato complex [YbIII(TMP)(H2O)3]+Cl− (Yb(TMP); 2) towards Staphylococcus aureus was investigated by stop‐flow microcalorimetry. By analyzing the obtained metabolic thermogenic curves, crucial parameters such as rate constant of bacterial growth (k), half inhibitory concentration (IC50), and generation time (tG) were determined. The antibacterial activities of the three compounds tested was 2>1>Yb3+, with an IC50 value of 273 mg/l for complex 2. The Yb3+ porphyrinato complex is proposed to benefit from synergetic effects of Yb3+ and the free porphyrin 1.
Influence of the Protonic State of an Imidazole‐Containing Ligand on the Electrochemical and Photophysical Properties of a Ruthenium(II)–Polypyridine‐Type Complex
Authors: Quaranta Annamaria , Lachaud Fabien , Herrero Christian , Guillot Régis , Charlot Marie‐France , Leibl Winfried , Aukauloo Ally
Published: July 2007

The synthesis and characterisation of [Ru(bpy)2(PhenImHPh)]2+ where PhenImHPh represents the 2‐(3,5‐di‐tert‐butylphenyl)imidazo[4,5‐f][1,10]phenanthroline ligand are described. The compounds issued from the three different protonic states of the imidazole ring [Ru(bpy)2(PhenImPh)]+ (I), [Ru(bpy)2(PhenImHPh)]2+ (II) and [Ru(bpy)2(PhenImH2Ph)]3+ (III) were isolated and spectroscopically characterised. The X‐ray structures of [Ru(bpy)2(PhenImPh)](PF6)⋅H2O⋅6 MeOH, [Ru(bpy)2(PhenImHPh)](NO3)2⋅H2O⋅3 MeOH and [Ru(bpy)2(PhenImH2Ph)](PF6)3⋅ 5 H2O are reported. Electrochemical data obtained on these complexes indicate almost no potential shift for the RuIII/II redox couple. Therefore a Coulombic effect between the imidazole ring and the metal centre can be ruled out. The monooxidised forms of I and II have been characterised by EPR spectroscopy and are reminiscent of the presence of a radical species. The emission properties of the parent compound [Ru(bpy)2(PhenImHPh)]2+ were studied as a function of pH and both the lifetimes and intensities decreased upon deprotonation. Photophysical properties, investigated in the absence and presence of an electron acceptor (methylviologen), were distinctly different for the three compounds. Transient absorption features indicate that unique excited states are involved. Theoretical data obtained from DFT calculations in water on the three protonic forms are presented and discussed in the light of the experimental results.
Researches on a Novel Method for Fluorination of Halopyridazine Derivatives in Ionic Liquid
Authors: Sun Li , Pei Wen
Published: July 2007

A novel method for fluorination of halopyridazine derivatives with potassium fluoride was performed using a green chemistry procedure, including ionic liquid as an environmentally benign reaction medium and microwave irradiation with high yield.
Theoretical Investigations on the Electronic and Optical Properties of Luminescent Poly(alkylthiophene‐co‐pyridine)
Authors: Wang Han‐Lu , Wang Xue‐Ye , Wang Ling , He Heng‐Liang , Liu Ai‐Hong
Published: July 2007

Quantum‐chemical techniques were applied to investigate a series of conjugated polymers: poly(3‐octylthien‐2,5‐ylene‐co‐pyrid‐2,6‐ylene) (p1), poly[pyrid‐2,6‐ylenebis(3‐octylthien‐2,5‐ylene)] (p2) and poly[pyrid‐2,5‐ylene‐ bis(3‐octylthien‐2,5‐ylene)] (p3) comprising alternating π‐excessive 3‐alkylthiophene and π‐deficient meta‐ or para‐linked pyridine moieties. Their ground state and excited state structures were optimized with density functional theory B3LYP method, and the optical properties were calculated by the time‐dependent density functional theory (TD‐DFT) and ZINDO/S methods. Their HOMO‐LUMO gaps (ΔH‐L), the lowest excitation energies (Eex), ionization potentials (IP) and electron affinities (EA) were obtained by extrapolating those of the polymers to the inverse chain length equal to zero (1/n=0). The calculated results showed that the decrease of pyridylene content increased the HOMO level and decreased the LUMO level while the para‐linkage further contributed to it. The IP are in the order: p1>p2>p3 but EA are: p1<p2<p3. In addition, the decrease of the pyridylene content and the para‐linked pyridylene in the backbone of the polythiophene resulted in a narrowed energy gap and bathochromic absorption and emission peaks.
L‐Prolinamide Catalyzed Aqueous Direct Aldol Reaction: an Environment‐friendly Method for the Synthesis of β‐Hydroxylketones
Authors: Peng Yi‐Yuan , Liu Han , Cui Ming , Cheng Jin‐Pei
Published: July 2007

An environment‐friendly L‐prolinamide catalyzed aldol reaction has been developed. The reaction exhibited broad substrate generality,and high yields with good diastereoselectivity were obtained for cyclic ketones. The simplicity of product isolation, usage of water as environmentally benign reaction medium, and the usage of cheap, readily available and recyclable catalyst make this process promising to be developed for large‐scale preparation of β‐hydroxyl ketones.
Novel N,N′‐Diacylhydrazine‐Based Colorimetric Receptors for Selective Sensing of Fluoride and Acetate Anions
Authors: Shi Da‐Qing , Wang Hai‐Ying , Li Xiao‐Yue , Yang Fang , Shi Jing‐Wen , Wang Xiang‐Shan
Published: July 2007

Three novel and simple N,N′‐diacylhydrazine‐based colorimetric receptors have been prepared. The binding properties of the receptors to anions such as F−, Cl−, Br−, AcO−, HSO4− and H2PO4− in acetonitrile solution were examined by UV‐Vis spectroscopy methods, which show high sensitivity and selectivity to F− and AcO− over other anions. The results indicated that a 1:1 stoichiometry complex was formed between the receptors and the anions, while 1H NMR titrations confirmed hydrogen binding interaction between the receptors and the anions.
Komplexität erhalten ‐ auch in heterogenen Lerngruppen: Aufgaben mit gestuften Lernhilfen
Authors: Stäudel Lutz , Franke‐Braun Gudrun , Schmidt‐Weigand Florian
Published: July 2007

In Folge von TIMSS und PISA haben sich viele Lehrkräfte gefragt, was sie denn tun können, um das kritisierte fragendentwickelnde Unterrichtsgespräch [1] zumindest teilweise durch ein anderes methodisches Vorgehen zu ergänzen, wenn nicht zu ersetzen. Die Alternativen mussten aber zumindest ebenso funktional und praktikabel sein wie das oft bemühte Wechselgespräch zwischen Lehrkraft und Lernenden. Von neuen Ansätzen wurde zudem erwartet, dass sie bei den Schülern kognitiv aktivierend wirken, indem sie z.B. die Bearbeitung anspruchsvoller Problemstellungen erlaubten.

Im Zuge von SINUS wurde eine Fälle von Methoden wieder entdeckt und reaktiviert oder in neuer Gestalt für den naturwissenschaftlichen Unterricht aufbereitet [2]. Kooperative Lernformen gehören zu diesem neuen Unterrichtsrepertoire ebenso wie das Lernen an Stationen oder der Einsatz von Methodenwerkzeugen [3, 4, 5]. Insbesondere Aufgaben, und zwar in Gestalt von Lernaufgaben, erfahren lebhaftes Interesse, und nicht zu Unrecht:

Zum einen überantwortet die Lehrkraft mit der gestellten Aufgabe einen Teil der Verantwortung für das Lernen den Schülern und Schülerinnen,

die notwendige Durcharbeitung einer Fragestellung oder eines Problems entspricht viel eher einer konstruktivistischen Sicht des Lernens,

und schließlich kann die Komplexität einer Fragestellung deutlich besser erhalten werden als in der kleinschrittigen Bearbeitung während eines Unterrichtsgesprächs.

Komplexere Aufgabenstellungen stoßen in der Praxis aber schnell an ihre Grenzen, wenn sie von Schülern unterschiedlicher Leistungsfähigkeit bearbeitet werden sollen. Wenn das verfügbare Vorwissen in großem Umfang differiert und außerdem die kognitiven Möglichkeiten sich innerhalb einer Lerngruppe stark unterscheiden, bedeuten manche Problemstellungen zumindest für einige eine deutliche Überforderung. Nicht zuletzt aus diesem Grund hat sich in den naturwissenschaftlichen Füchern in der Vergangenheit kaum eine Kultur anspruchsvoller Aufgabenstellungen entwickeln können; schließlich mag man es weder den Schülern zumuten, sich während einer Aufgabenbearbeitung regelmäßig als Hilfe bedürftig zu outen, noch kann sich eine Lehrkraft gleichzeitig mehreren Unterstützung fordernden Kleingruppen zuwenden. Was also tun?
CHEMDLA ‐ ein Programm zur Simulation des dendritischen Kristallwachstums im Chemieunterricht
Authors: Oetken Marco , Höltkemeier Dirk
Published: July 2007

Bei der Abscheidung von Metallen aus ihren Lösungen und bei der Kristallisation von Salzen wachsen unter bestimmten Bedingungen dendritische, d.h. baumartig verzweigte Kristalle. Über dieses erstaunliche und ästhetisch reizvolle Phänomen haben wir schon in früheren Publikationen berichtet und Versuchsansätze vorgestellt, mit denen es unter schulrelevanten Bedingungen zu beobachten ist [1‐4]. In diesem Zusammenhang haben wir bereits auf das Modell des diffusionskontrollierten Wachstums (engl. diffusion‐limited aggregation, DLA) hingewiesen. Das ursprünglich aus wissenschaftlichen Motiven entwickelte Modell ist auch für den Chemieunterricht interessant, da es die Möglichkeit eröffnet, die Ursachen des dendritischen Kristallwachstums mit einem dynamischen Teilchenmodell aufzuklären [5]. Zur Thematisierung des DLA‐Modells standen bisher jedoch nur Modellvarianten aus dem Internet zur Verfügung, die aufgrund einer mangelnden Anschaulichkeit oder unklar definierten Eingriffsmöglichkeiten nur bedingt im Unterricht einsatzfähig sind. In diesem Beitrag stellen wir daher nun ein neues DLA‐Simulationsprogramm vor, das speziell für die Thematisierung des dendritischen Kristallwachstums im Chemieunterricht entwickelt wurde.
Co‐occurrence of anxiety and depressive disorders in a community sample of older people: results from the MRC CFAS (Medical Research Council Cognitive Function and Ageing Study)
Authors: Kvaal Kari , McDougall Fiona A. , Brayne Carol , Matthews Fiona E. , Dewey Michael E.
Published: July 2007

Background

Few population‐based studies have examined the whole range of subthreshold syndromes and disorders of anxiety and depression in older people.

Aims

To investigate the co‐occurrence of anxiety and depressive syndromes in older people. Associations between these conditions and personal and environmental factors are examined.

Method

MRC CFAS included 13, 004, age 65 years and above, who completed the initial screening interview. A stratified random subsample of 2, 640 participated in the assessment interview where the Geriatric Mental State Examination (GMS) was administered. The AGECAT diagnostic system was used to generate subthreshold and disorder‐level of anxiety and depression as well as the combination of these into eight syndromes categories plus a group without any of the syndromes categories. Prevalences, unadjusted and adjusted odds ratios are calculated for the syndrome categories in relation to cross‐sectional personal and environmental factors, and odds ratios of subthreshold and disorders level are estimated.

Results

The overall prevalence of anxiety and depressive disorders are 3.1% and 9.7% respectively. The overall prevalence of either anxiety or depressive disorder (anxiety disorder with subthreshold depression, mixed anxiety and depressive disorder with subthreshold anxiety) where they overlapped is 8.4%. The highest Odds Ratios unadjusted and adjusted for age and gender, of anxiety and depressive disorders and significant for trend are found for increasing disability. Disability has a strong relationship with all the co‐morbid syndrome categories. In all analyses women showed significant higher estimates than men.

Conclusions

Our study demonstrated high estimates where anxiety and depression occurred in parallel both as disorders and as subthreshold syndromes. Copyright © 2007 John Wiley & Sons, Ltd.
Thyroid dysfunction in laryngectomees—10 years after treatment
Authors: Ho Ambrose Chung‐Wai , Ho Wai‐Kuen , Lam Paul Kin‐Yip , Yuen Anthony Po‐Wing , Wei William Ignace
Published: July 2007

Background.

Hypothyroidism is 1 of the complications that follow treatment of various head and neck cancers. In the literature, reviews using different primary sites and differences in treatment modalities make comparison of post‐treatment hypothyroidism not possible. The objective of this study was to evaluate the incidence of hypothyroidism in a homogenous group of patients who were treated with total laryngectomy and irradiation for laryngeal carcinoma and to assess the importance of different variables in the occurrence of hypothyroidism.

Methods.

A retrospective review of 147 total laryngectomy patients between 1993 and 2003 was carried out. Serum thyroxine level and free T4 levels were assessed in all patients. Hypothyroidism was classified as subclinical (increased thyroid‐stimulating hormone and normal free T4 levels) and clinical (increased thyroid‐stimulating hormone and decreased free T4 levels).

Results.

The results showed that the overall incidence of hypothyroidism was 49% (44% subclinical and 5% clinical). Hemithyroidectomy and advanced tumor staging were risk factors for the development of hypothyroidism in these patients (p < .05) with a relative risk of 2.1 (CI 95%, 1.4–3.1) and 1.3 (CI 95%, 1.1–1.6), respectively. During follow‐up, 19.9% of patients developed hypothyroidism at 3 years, 38.6% at 6 years; at 10 year follow‐up, 93.3% of them had hypothyroidism.

Conclusions.

In conclusion, hypothyroidism is a frequent complication in patients treated with radiotherapy and total laryngectomy for laryngeal cancer, especially when treatment includes hemithyroidectomy. These patients should have their thyroid function evaluated periodically even 10 years after treatment. © 2007 Wiley Periodicals, Inc. Head Neck 2008
Synthesis of Nicotinamide Adenine Dinucleotide (NAD) Analogues with a Sugar Modified Nicotinamide Moiety
Authors: Goulioukina Natasha , Wehbe Johny , Marchand Damien , Busson Roger , Lescrinier Eveline , Heindl Dieter , Herdewijn Piet
Published: July 2007

The synthesis of nicotinamide adenine dinucleotide (NAD) analogues in which the ribose unit of the nicotinamide moiety is replaced by a hexitol, altritol, and cyclohexenyl sugar mimic is described.
Diterpenoid and Phenolic Compounds from Juncus effusus L.
Authors: Yang Guang Zhong , Li Hong Xia , Song Fa Jun , Chen Yu
Published: July 2007

A novel diterpene, named effusenone A (1a), which is the first reported rosane‐type diterpene from a Juncaceae plant, and three novel phenolic compounds, 5‐(hydroxymethyl)‐1‐methylphenanthrene‐2,7‐diol (4), 1‐methylpyrene‐2,7‐diol (5), and 7‐methoxy‐8‐methylpyren‐2‐ol (6) were isolated from the stem of Juncus effusus L. by normal‐phase and reversed‐phase silica gel column chromatography. Their structures were identified by spectroscopic methods, especially 2D‐NMR techniques.
Practical Enzymatic Desymmetrization of 2‐(Ethoxycarbonyl)propane‐1,3‐diyl Dihexanoate and Model Cyclization for the A–D Ring System of Lysergic Acid
Authors: Miyata Sachiho , Kumamoto Takuya , Ishikawa Tsutomu
Published: July 2007

Porcine pancreas lipase‐catalyzed hydrolysis of symmetrical 2‐(ethoxycarbonyl)propane‐1,3‐diyl dihexanoate, under the modified conditions of the Seebach protocol, afforded a desymmetrized monohexanoate in 40–51% yield with 91–94% ee, even in a gram‐scale reaction. The absolute configuration of a half‐hydrolyzed (−)‐product was determined to be (R) by conversion to a known 2‐methylpropane‐1,3‐diol derivative. Samarium iodide‐induced radical cyclization of 2‐oxo‐3‐phenylethylamine with a C4 unit on the N‐atom, derived from the racemic monohexanoate, afforded a 3‐phenylpiperidine derivative as a model construction of the A–D ring system of lysergic acid.
Culturing adult human bone marrow stem cells on gelatin scaffold with pNIPAAm as transplanted grafts for skin regeneration
Authors: Perng Cherng‐Kang , Kao Chung‐Lan , Yang Yi‐Ping , Lin Han‐Tso , Lin Wen‐Bin , Chu Yue‐Ru , Wang Hsiao‐Jung , Ma Hsu , Ku Hung‐Hai , Chiou Shih‐Hwa
Published: July 2007

Skin tissue engineering is a possible solution for the treatment of extensive skin defect. The ultimate goal of skin tissue engineering is to restore the complete functions of native skin, but until now the structures and functions of skins are only partially restored. By negative immunoselection (CD45 and glycophorin A), we isolated and cultivated adult human bone marrow stem cells (hBMSCs) that are of multilineage differentiation potential. In this study, we first demonstrated that by using gelatin/thermo‐sensitive poly N‐isopropylacrylamide (pNIPAAm) and the immunocompromised mice model, the hBMSCs possess the differentiation potential of epidermis and the capability of healing skin wounds. The in vitro observations and the results of the scanning electron microscope showed that the hBMSCs can attach and proliferate in the gelatin/thermo‐sensitive pNIPAAm. To further monitor the in vivo growth effect of the hBMSCs in the skin‐defected nude mice, the green fluorescence protein (GFP) gene was transduced into the hBMSCs by the murine stem cell viral vector. The results showed that the rates of cell growth and wound recovery in the hBMSC‐treated group were significantly higher than those in the control group, which was only treated with the gelatin/pNIPAAm (p < 0.01). More importantly, the re‐epithelialization markers of human pan‐cytokeratin and E‐cadherin were significantly increased on day 7, day 14, and day 21 after the hBMSC‐scaffold with the pNIPAAM in the mice with skin defects (p < 0.05). Moreover, the stem cell markers of human CD13 and CD105 were gradually decreased during the period of wound healing. In sum, this novel method provides a transferring system for cell therapies and maintains its temperature‐sensitive property of easy‐peeling by lower‐temperature treatment. In addition, the in vitro and in vivo GFP imaging systems provide a new imaging modality for understanding the differentiation process and the effective expression of stem cells in wound healing. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Characterization and in vitro evaluation of biphasic calcium pyrophosphate–tricalciumphosphate radio frequency magnetron sputter coatings
Authors: Takahashi K. , van den Beucken J.J.J.P. , Wolke J.G.C. , Hayakawa T. , Nishiyama N. , Jansen J.A.
Published: July 2007

The objective of this study was to characterize the physicochemical, dissolution, and osteogenic properties of radio frequency magnetron sputtered dicalcium pyrophosphate/tricalciumphosphate (Pyro/TCP) and hydroxylapatite (HA) coatings. Therefore Pyro/TCP and HA coatings were deposited on grit‐blasted titanium discs. The results showed that the deposited coatings were amorphous and changed into a crystalline structure after IR heat‐treatment of 550°C for HA and 650°C for Pyro/TCP. Heat‐treated HA coatings appeared to be stable during immersion in simulated body fluid (SBF), that is no changes in the XRD pattern were observed. Also, no dissolution of the coating was observed by scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) revealed that the Ca/P ratio of the HA coatings remained constant during SBF immersion. On the other hand, the heat‐treated Pyro/TCP coatings showed a surface reaction of calcium pyrophosphate into a β‐tricalcium phosphate phase during SBF immersion. This was confirmed by EDS analysis. Rat bone marrow‐derived osteoblast‐like cells cultured on the heat‐treated substrates showed that cell proliferation and differentiation occurred on both types of bioceramic coatings. No significant differences for proliferation and early differentiation were observed between cells cultured on heat‐treated Pyro/TCP and HA at individual time points. However, osteocalcin expression, a late marker for osteoblast‐like cell differentiation, was significantly increased after 12 days of culture on HA‐coatings. These results were confirmed by SEM observations and suggest increased osteogenic properties for HA‐coatings over Pyro/TCP‐coatings. Additional research is necessary to obtain conclusive evidence on the in vivo osteogenic capacity of Pyro/TCP coatings. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008