bluuebunny/crossref_metadata_2025 huggingface dataset:
Eicosanoids in insect immunity: Bacterial infection stimulates hemocytic phospholipase A2 activity in tobacco hornworms
Authors: Tunaz Hasan , Park Youngjin , Büyükgüzel Kemal , Bedick Jon C. , Nor Aliza A.R. , Stanley David W.
Published: December 2002

Intracellular phospholipase A2 (PLA2) is responsible for releasing arachidonic acid from cellular phospholipids, and is thought to be the first step in eicosanoid biosynthesis. Intracellular PLA2s have been characterized in fat body and hemocytes from tobacco hornworms, Manduca sexta. Here we show that bacterial challenge stimulated increased PLA2 activity in isolated hemocyte preparations, relative to control hemocyte preparations that were challenged with water. The increased activity was detected as early as 15 s post‐challenge and lasted for at least 1 h. The increased activity depended on a minimum bacterial challenge dose, and was inhibited in reactions conducted in the presence of oleyoxyethylphosphorylcholine, a site‐specific PLA2 inhibitor. In independent experiments with serum prepared from whole hemolymph, we found no PLA2 activity was secreted into serum during the first 24 h following bacterial infection. We infer that a hemocytic intracellular PLA2 activity is increased immediately an infection is detected. The significance of this enzyme lies in its role in launching the biosynthesis of eicosanoids, which mediate cellular immune reactions to bacterial infection. Arch. Insect Biochem. Physiol. 52:1–6, 2003. © 2003 Wiley‐Liss, Inc.
Positive and negative modulation of Bombyx mori adenylate cyclase by 5‐phenyloxazoles: Identification of octopamine and tyramine receptor agonists
Authors: Khan Md. Anwar Arfien , Nakane Toshiya , Ohta Hiroto , Ozoe Yoshihisa
Published: December 2002

Nineteen 5‐phenyloxazoles (5POs) were examined for their ability to modulate adenylate cyclase by measuring cAMP produced in head membrane homogenates of fifth instar larvae of the silkworm Bombyx mori. Among the compounds tested, 5‐(4‐methoxyphenyl)oxazole (9) and the 2,6‐dichlorophenyl congener showed the highest activation of adenylate cyclase; both compounds produced approximately half the level of cAMP produced by the action of octopamine (OCT). The OCT receptor antagonists chlorpromazine, mianserin, and metoclopramide attenuated 9‐stimulated cAMP production. In contrast, 5‐(4‐hydroxyphenyl)oxazole (8) and the 4‐cyanophenyl congener attenuated both OCT‐stimulated and basal cAMP production. The tyramine (TYR) receptor antagonist yohimbine inhibited the negative effect of 8. These findings indicate that the 5PO class of compounds includes both positive and negative modulators of adenylate cyclase in the heads of B. mori larvae, and that 9 and 8 are OCT and TYR receptor agonists, respectively. These compounds might prove useful for a pharmacological dissection of biogenic amine receptors. Arch. Insect Biochem. Physiol. 52:7–16, 2003. © 2003 Wiley‐Liss, Inc.
Entomogenous fungus Nomuraea rileyi inhibits host insect molting by C22‐oxidizing inactivation of hemolymph ecdysteroids
Authors: Kiuchi Makoto , Yasui Hiroe , Hayasaka Shoji , Kamimura Manabu
Published: December 2002

The entomogenous fungus Nomuraea rileyi reportedly secretes a proteinaceous substance inhibiting larval molt and metamorphosis in the silkworm Bombyx mori. We studied the possibility that N. rileyi controls B. mori development by inactivating hemolymph molting hormone, ecdysteroids. Incubation of ecdysone (E) and 20‐hydroxyecdysone (20E) in fungal‐conditioned medium resulted in their rapid modification into products with longer retention times in reverse‐phase HPLC. Each modified product from E and 20E was purified by HPLC, and identified by NMR as 22‐dehydroecdysone and 22‐dehydro‐20‐hydroxyecdysone. Some other ecdysteroids with a hydroxyl group at position C22 were also modified. Injection of the fungal‐conditioned medium into Bombyx mori larvae in the mid‐4th instar inhibited larval molt but induced precocious pupal metamorphosis, and its injection into 5th instar larvae just after gut purge blocked pupal metamorphosis. In hemolymph of injected larvae, E and 20E disappeared and, in turn, 22‐dehydroecdysone and 22‐dehydro‐20‐hydroxyecdysone accumulated. These results indicate that N. rileyi secretes a specific enzyme that oxidizes the hydroxyl group at position C22 of hemolymph ecdysteroids and prevents molting in B. mori larvae. Arch. Insect Biochem. Physiol. 52:35–44, 2003. © 2003 Wiley‐Liss, Inc.
Monoclonal antibodies to elongation factor‐1α inhibit in vitro translation in lysates of Sf21 cells
Authors: Stuart M.K. , Chamberlain N.R.
Published: December 2002

Elongation factor‐1α (EF‐1α) is an enzyme that is essential for protein synthesis. Although EF‐1α offers an excellent target for the disruption of insect metabolism, agents known to interfere with EF‐1α activity are toxic to humans. In this article, we describe the development of monoclonal antibodies (MAbs) that can disrupt the activity of insect EF‐1α without cross‐reacting with the human enzyme. MAbs were generated to EF‐1α from Sf21 cells derived from the fall armyworm, Spodoptera frugiperda, by immunizing mice with EF‐1α eluted from SDS‐PAGE gels. The MAbs reacted with EF‐1α in eggs and first through fifth instars of the fall armyworm in immunoblots of SDS‐PAGE gels, but did not recognize EF‐1α in human carcinoma cells and normal tissues. MAbs with the ability to recognize EF‐1α in its native conformation, identified through immunoprecipitation experiments, were added to Sf21 cell lysates to determine whether the antibodies could inhibit incorporation of [35S]methionine into newly synthesized in vitro translation products. Of the four EF‐1α‐specific MAbs tested, three significantly inhibited protein synthesis when compared to the negative control antibody (P < 0.001, one‐way ANOVA; followed by Dunnett's test, P < 0.05). Arch. Insect Biochem. Physiol. 52:17–34, 2003. © 2003 Wiley‐Liss, Inc.
Hemolymph ecdysteroids do not affect vitellogenesis in the lubber grasshopper
Authors: Hatle John D. , Juliano Steven A. , Borst David W.
Published: December 2002

The role of hemolymph ecdysteroids in the reproduction of non‐dipteran insects is unclear. We examine the role(s) of hemolymph ecdysteroids during egg production in the lubber grasshopper, Romalea microptera. In all individuals, hemolymph ecdysteroids rose to a sharp peak with similar maxima and then fell to undetectable levels. The time from the adult molt to the maximum ecdysteroid titer (Emax titer) varied in response to food availability, whereas the time from Emax titer to oviposition was unrelated to food availability. Because both the timing of egg production and the timing of Emax responded similarly to environmental changes, ecdysteroids may be involved in egg production. We hypothesized that this role is the stimulation of vitellogenesis. Ovariectomized females had vitellogenin but no ecdysteroids, so ecdysteroids are not necessary for vitellogenin production. In addition, treatment of females with ecdysteroids altered neither Vg titers nor ovarian growth. Ovarian ecdysteriods increased at the same age in development as hemolymph ecdysteroids. In contrast to hemolymph ecdysteroids, ovarian ecdysteroids persisted until oviposition. Despite this, [3H]ecdysone injected into the hemolymph was detected later only at very low levels in the ovary, suggesting that hemolymph ecdysteroids are not sequestered by the ovary. In summary, our studies indicate that hemolymph ecdysteroids in adult females of the lubber grasshopper are associated with the timing of egg production, but they neither regulate vitellogenesis nor act as a source of ecdysteroids for the ovary. Arch. Insect Biochem. Physiol. 52:45–57, 2003. © 2003 Wiley‐Liss, Inc.
Environment for engineering design, analysis, and simulation for education using MATLAB via the World Wide Web. I. Environment description and development
Authors: Shiakolas P. S. , Chandra V. , Kebrle J.
Published: December 2002

In Part I of this paper, we present the development of tools for engineering design, analysis and simulation over the World Wide Web accessible via a web browser. The tools utilize the power and versatility provided by the software package MATLAB and the features of the web toolbox. This work aims at improving the understanding of engineering fundamentals through interactive real‐time simulation. The current environment consists of a number of modules for the interactive real‐time simulation of linear time invariant dynamic systems and for analysis and synthesis of planar mechanisms. The properly designed input interface facilitates the easy understanding of the required inputs from the user. The returned information to the user's web browser consists of ASCII (textual), graphical, and pictorial representations, and provides information of the input and solutions. In addition, where appropriate, the user has the option to view an animation of the system. This work demonstrates advantages of using this technology to aid in classroom instruction, ease of implementation for application in other domains, and provides valuable analysis tools to students and engineering professionals. Examples will be presented in Part II to demonstrate the developed tools. Users with access to the Internet can use the developed mechanism synthesis and analysis modules at http://zodhia.uta.edu/development. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 99–108, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10018
Environment for engineering design, analysis, and simulation for education using MATLAB via the World Wide Web. II. Representative examples—System simulation and planar mechanism synthesis and analysis
Authors: Shiakolas P. S. , Chandra V. , Kebrle J. , Wilhite D.
Published: December 2002

In Part II of this paper, we present representative examples that demonstrate the capabilities and features of the developed education environment that allows one to simulate in real time engineering systems utilizing the power of MATLAB through a web browser interface. The web‐based graphical user interface (GUI) provides the means for the user to input system parameters and the display of the analysis results. The examples presented demonstrate the required clarity of the developed GUI, and the nature and type of the results returned to the web browser of the user in real time. This environment has the capability to return to the user textual, graphical, pictorial, and animation related material. The user has the option to download analysis results in any of the generated forms to the client computer. This work demonstrates the ease of implementation and advantages of using this technology to aid in classroom instruction. Users with Internet can access the developed simulation modules at http://zodhia.uta.edu/development. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 109–120, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10019
Interactive Web‐based package for computer‐aided learning of structural behavior
Authors: Yuan X. F. , Teng J. G.
Published: December 2002

This paper presents an innovative Web‐based package named CALSB for computer‐aided learning of structural behavior. The package was designed to be widely accessible through the Internet, user‐friendly by the automation of many input functions and the extensive use of cursor movements, and dynamically interactive by linking all input and output data to a single graphical display on the screen. The package includes an analysis engine based on the matrix stiffness method, so the response of any two‐dimensional skeletal structure can be predicted and graphically displayed. The package thus provides a virtual laboratory environment in which the user can “build and test” two‐dimensional skeletal structures of unlimited choices to enhance his understanding of structural behavior. In addition, the package includes two other innovative features, structural games and paradoxes. The structural games in the package represent perhaps the first attempt at intentionally combining the learning of structural behavior with joy and excitement, while the structural paradoxes provide a stimulating environment conducive for the development of creative problem solving skills of the user. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 121–136, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10020
Web‐based Thermodynamics Tables Wizard
Authors: Ngo C. C. , Lai F. C.
Published: December 2002

This paper presents the Web‐based Thermodynamics Tables Wizard and how it can be used for online courses or web‐teaching to accommodate the need of students at different levels in looking up thermodynamics properties. It can be used as a stand‐alone study aid or an add‐on component for any online Thermodynamics course. The implementation of this Web‐based module has greatly enhanced the learning experience of students in the study of Thermodynamics. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 137–143, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com); DOI 10.1002/cae.10022
Use of process simulators for the unit operations education of undergraduate chemical engineers
Authors: Fernandes Fabiano A. N.
Published: December 2002

Computer aided design has become extremely popular and its use in classroom can be very helpful, adding more analysis capabilities to all chemical engineering areas. Process simulators, such as Hysys and Aspen, are complex tools and students tend to have doubts when they start using them. This article presents Hyduc, an exercise/tutorial software, developed to introduce process simulators to undergraduate students and to provide unit operation courses with realistic exercises involving simulation of chemical processes. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 155–160, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10023
Digital simulation of wave motion
Authors: Riera Jaime , Giménez Marcos H. , Vidaurre Ana , Monsoriu Juan A.
Published: December 2002

Information and communication technologies have been shown to be very effective in the transmission of scientific knowledge. Nowadays, the development of software and hardware makes it possible to simulate processes as close to reality as we want. However, when we are trying to explain some complex physical processes, it is better to simplify the problem by means of simplified pictures of the total process. In the present work, we analyze the design of a simulation program of wave motion developed in our laboratory. The aim of the program is to help students to understand the basic concepts of the wave motion. For this reason, we have paid special attention to interactivity and graphic aspects. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 161–166, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10025
TriMeDeC tool for preparing visual teaching materials based on triangular networks
Authors: Krivograd Sebastian , Žalik Borut , Novak Franc
Published: December 2002

Triangular meshes are frequently used to present different natural phenomena and free‐form shapes. They are generated by different mathematical, simulation, and design tools. Usually they contain a huge number of triangles, which represents a serious obstacle for storing, manipulation, and transmission via internet. However, triangular meshes can be simplified (decimated) yet still preserving the main features of the original mesh. In this paper, TriMeDeC tool for decimation, undecimation, and compression of triangular meshes is presented. The tool helps teachers and students to visualize triangular meshes and simplify them in an interactive way. Its salient feature is an effective data compression algorithm, which produces 2 to 3.5 times smaller output files than the popular WinZIP algorithm. TriMeDeC is very simple to use and can be easily employed by teachers and students. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 144–154, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10031
Non‐triviality and identification of a constrained Tucker3 analysis
Authors: ten Berge Jos M. F. , Smilde Age K.
Published: December 2002

Properties of estimated parameters of models of chemical systems are important. This paper focuses on two properties of such estimated parameters: triviality and uniqueness. If a chemical system is analyzed using a Tucker3 model, then the resulting core can often be rotated to a simple structure containing zeros. This means that it is possible that a prespecified pattern of zero and non‐zero elements of the core, as used in e.g. constrained Tucker3 models, is not an active constraint; that is, the zeros can be obtained trivially for free. Once a non‐trivial pattern of zeros in the core is specified, the question arises whether this pattern is sufficient for obtaining unique loadings. Both issues are discussed in this paper and it is shown that the model used by Gurden et al. (J. Chemometrics 2001; 15: 101–121) does essentially involve a non‐trivial core and implies rotationally unique parameter estimates. Copyright © 2002 John Wiley & Sons, Ltd.
Application of equality constraints on variables during alternating least squares procedures
Authors: Van Benthem Mark H. , Keenan Michael R. , Haaland David M.
Published: December 2002

We describe several methods of applying equality constraints while performing procedures that employ alternating least squares. Among these are mathematically rigorous methods of applying equality constraints, as well as approximate methods, commonly used in chemometrics, that are not mathematically rigorous. The rigorous methods are extensions of the methods described in detail in Lawson and Hanson's landmark text on solving least squares problems, which exhibit well‐behaved least squares performance. The approximate methods tend to be easy to use and code, but they exhibit poor least squares behaviors and have properties that are not well understood. This paper explains the application of rigorous equality‐constrained least squares and demonstrates the dangers of employing non‐rigorous methods. We found that in some cases, upon initiating multivariate curve resolution with the exact basis vectors underlying synthetic data overlaid with noise, the approximate method actually results in an increase in the magnitude of residuals. This phenomenon indicates that the solutions for the approximate methods may actually diverge from the least squares solution. Copyright © 2002 John Wiley & Sons, Ltd.
A simple spatio‐temporal procedure for the prediction of air pollution levels
Authors: Mendes Jorge M. , Turkman Kamil F.
Published: December 2002

In this paper we study the spatio‐temporal behaviour of air pollutants measured daily over the city of Lisbon, Portugal. Our specific aim is to predict air pollutant levels in time and space over a fine grid of locations based on observations from a small number of monitoring sites. Our suggested prediction procedure is based on the simple and intuitive idea of first making predictions in time at the monitoring sites and then extending these predictions in space to locations other than the monitoring sites using kriging methods. Copyright © 2002 John Wiley & Sons, Ltd.
Gedanken zur Zukunft der Feststoffverfahrenstechnik
Authors: Feise H.J.
Published: December 2002

Die chemische Industrie erlebt derzeit große Veränderungen. Für die Zukunft erwarten die im „Solids Processing Industrial Network“ beteiligten Experten, dass sich zwei verschiedene Arten von chemischen Anlagen entwickeln: einerseits die vielseitige, modularisierte Mehrzweckanlage und andererseits „World scale“‐Großanlagen. Gleichzeitig wird der bereits hohe Anteil von Feststoffen unter den Produkten der chemischen Industrie weiter steigen und neue Anforderungen stellen: Die Kleinmengenprodukte müssen individuell auf die Bedürfnisse des jeweiligen Kunden zugeschnitten werden, wodurch Product Design zu einer den Wettbewerb bestimmenden Technologie wird. Bei Großanlagen müssen neue Technologien entwickelt werden, welche die notwendigen, hohen Durchsätze bereitstellen und außerdem vom Labor‐ auf World scale‐Maßstab hochskaliert werden können. Einen erheblichen Anteil am künftigen Erfolg wird die Automatisierung haben, deren Einsatz zum Großteil von der Verfügbarkeit geeigneter Inline‐Messsysteme und der Entwicklung von Modellen zur Simulation des Prozesses und der dazugehörigen Partikeleigenschaften abhängen wird.
Einfluss der Reaktionsparameter bei polymeranalogen Umsetzungen in der Schmelze am Beispiel der Umsetzung von Poly(styrol‐co‐acrylnitril) mit Aminoalkoholen
Authors: Becker H.G. , Schmidt‐Naake G.
Published: December 2002

No abstracts.
Experimentelle Untersuchung und Modellierung der homogen‐katalytischen Veresterung
Authors: Marr R. , Rohde C. , Siebenhofer M.
Published: December 2002

No abstracts.
Messung des lokalen Wärmeübergangs im Einlaufbereich von Rohren nach Querschnittsänderungen
Authors: Woche H. , Specht E. , Schmidt J.
Published: December 2002

No abstracts.
Erfassung der Lamellenparameter an Hohlkegeldüsen mit der Particle Imaging Velocimetry
Authors: Broll P. , Walzel P.
Published: December 2002

No abstracts.
Zur Berechnung von Haftkräften an rauigkeitsbehafteten Oberflächen
Authors: Hoffmann B. , Weyrauch S. , Kubier B.
Published: December 2002

No abstracts.
Modellbasierte Messung der Monomerkonzentrationen für eine Emulsionspolymerisation – Vergleich Reaktionskalorimetrie und Zustandsschätzung
Authors: Gesthuisen R. , Krämer S.
Published: December 2002

No abstracts.
Elektrochemische Wasserenthärtung mit Kationenaustauschern auf der Basis leitfähiger Polymere
Authors: Weidlich C. , Mangold K.‐M. , Jüttner K.
Published: December 2002

No abstracts.
Selbstentzündung von Stäuben und Schüttgütern bei vermindertem Sauerstoffgehalt
Authors: Schmidt M. , Malow M. , Lohrer C. , Krause U.
Published: December 2002

No abstracts.
Effiziente Überwachung biotechnischer Prozesse mittels Titration
Authors: Feitkenhauer H.
Published: December 2002

No abstracts.
Schnelle Charakterisierung mikrobiologischer Stoffwechselleistungen mittels automatisiertem Biosensor
Authors: Winter C. , Leifheit M. , Tilli A. , Krüger K. , Mohr K.‐H.
Published: December 2002

No abstracts.
Erprobung einer Verfahrenskombination aus Hochdruck‐Feststoffextraktion und Hochdruck‐Absorption am Beispiel der Aromengewinnung
Authors: Seidel O. , Steiner R.
Published: December 2002

No abstracts.
Auswirkung einer mechanischen Vorbehandlung auf das anaerobe Abbauverhalten von feuchten organischen Feststoffen
Authors: Mundhenke R. , Baaden A. , Müller J. , Schwedes J.
Published: December 2002

No abstracts.
Ein wenig beachteter Aspekt der Chemiedidaktik: Die Person des Didaktikers
Authors: Martin‐Beyer Wolfgang
Published: December 2002

DIE FALLENDEN STUDENTENZAHLEN in den Studiengängen der Chemie werden vielfach dem gymnasialen Chemieunterricht zur Last gelegt [1]. Dabei nehmen kritische Stimmen zum Mittelstufenunterricht [2] zu, in dem die Weichen für das Wahlverhalten in der Oberstufe und fürs Studium gestellt werden. Auch in CHEMKON häufen sich in der letzten Zeit Artikel, in denen neue Konzepte für den Chemieunterricht gefordert oder vorgeschlagen werden oder in denen gar eine gänzlich neue Herangehensweise gefordert wird. Dies wird flankiert von einer Vielzahl von regionalen Schülerwettbewerben und örtlichen Schülerlaboren.

Vereinzelt beginnen auch Untersuchungen der Gründe des Unbehagens. Ein Aspekt scheint mir dabei entweder zu wenig oder zu selten bedacht oder ausgesprochen zu werden: die personale Komponente der Fachdidaktik, d.h. die Fachdidaktiker1 selbst. Ich möchte meine Ansichten begründen aus der Beobachtung a) von Zeitschriftenartikeln und b) von Fachvorträgen.
Chemie im Kontext auch für die Sekundarstufe I: Cola und Ketchup im Anfangsunterricht
Authors: Schmidt Silvia , Rebentisch Detlef , Parchmann Ilka
Published: December 2002

COLA UND KETCHUP, das klingt nach einem neuerlichen Aufwärmen der Forderung nach einer stärkeren Alltagsorientierung des Chemieunterrichts, vielleicht bei vielen verbunden mit der Sorge, die fachliche Tiefe fiele rein oberflächlichen Betrachtungen alltäglicher Phänomene zum Opfer oder die interne Systematik des Fachs würde verloren gehen. Wir stimmen Hans Rudolf Christen zu, wenn er feststellt, dass der gymnasiale Chemieunterricht nicht zur „Haushaltskunde”︁ werden darf [1]. Mit Cola und Ketchup kann aber auch an grundlegende Forderungen aus der Lehr‐Lern‐Forschung erinnert werden: Das Aufgreifen von Interessen und Fragen der Schülerinnen und Schüler sowie die Integration komplexer und alltagsnaher, authentischer Problemstellungen in den Unterricht stellt ein zentrales Element der Ansätze zum situierten oder problemorientierten Lernen dar [2, 3]. Welche Fragen ergeben sich diesbezüglich rund um Cola oder Ketchup, die auch zur Erarbeitung grundlegender und anschlussfähiger chemischer Kenntnisse führen können? (Wie) Werden damit Ziele im Sinne einer erfolgreichen Kompetenzentwicklung oder dem Aufbau einer „Scientific Literacy”︁ [4] realisiert? (Wie) Können neue Impulse oder andere konzeptionelle Ansätze tatsächlich zu einer (nachhaltigen) Veränderung von Unterricht führen? Diese Fragen sollen im nachfolgenden Beitrag auf der Basis konzeptioneller Überlegungen und unterrichtspraktischer Erfahrungen erörtert werden; ferner wird ein Projekt zur Weiterentwicklung von Unterricht vorgestellt, in dessen Rahmen die hier beschriebenen Arbeiten einzuordnen sind.
Sandwich and Half‐Sandwich (Imido)niobium Complexes
Authors: Antiñolo Antonio , Fajardo Mariano , Otero Antonio , Prashar Sanjiv
Published: December 2002

This review discusses the study we have carried out towards the synthesis, structure and reactivity of (imido)niobium complexes, which contain at least one cyclopentadienyl ligand. The following families of niobium complexes are described: (i) half‐sandwich imido complexes; (ii) metallocene imido compounds; (iii) imido complexes containing ansa‐cyclopentadienyl ligands; (iv) dinuclear imido complexes such as [{Nb(η5‐C5H4SiMe3)2Cl}2(μ‐1,3‐N2C6H4)]. In addition we describe spectroscopic and structural features of the (imido)niobium complexes. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2003)
Selective Insertion of Dioxygen into an (η2‐C60)−Ir Bond: Synthesis and Structure of the First Metallacyclic Complex with a σ‐Coordinated Fullerene Molecule
Authors: Usatov Alexander V. , Martynova Ekaterina V. , Dolgushin Fedor M. , Peregudov Alexander S. , Antipin Mikhail Yu. , Novikov Yurii N.
Published: December 2002

Oxidation of the carboranyliridium fullerene complex [(η2‐C60)Ir(o‐HCB10H9CCH2PPh2‐B,P)(tBuNC)2] (I) in CHCl3 solution by O2 occurs by a selective insertion of the dioxygen molecule into the longest Ir−C bond (in the trans‐position relative to the B‐σ‐carboranyl fragment) to give a new metal complex [σ‐C60OO‐Ir(o‐HCB10H9CCH2PPh2‐B,P)(tBuNC)2] (II). Complex II was isolated and characterized analytically and by UV, IR, 1H and 31P NMR spectroscopy. An X‐ray diffraction study of II showed that this complex contains a cyclic iridaperoxide fragment in which the fullerene cage is σ‐coordinated to the iridium atom. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Self‐Assembly of a One‐Dimensional Silver Complex Containing Two Kinds of Helical Chains
Authors: Sun Daofeng , Cao Rong , Sun Yanqiong , Bi Wenhua , Li Xing , Hong Maochun , Zhao Yingjun
Published: December 2002

Self‐assembly of the potassium sulfonate salt K2pesp [H2pesp = piperazine‐1,4‐bis(2‐ethanesulfonic acid] with piperazine (PIP) and a silver(I) salt in solution allows the preparation of a novel one‐dimensional helical polymer [Ag(PIP)]n·[Ag(pesd)]n·2nH2O (1), which is made up of two independent silver‐containing helical chains, namely [Ag(PIP)]n and [Ag(pesd)]n. There is no direct bonding interaction between the two chains, and the hydrogen bonds between the chains give 1 a two‐dimensional layer supramolecular architecture. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Unprecedented Change of the Jahn−Teller Axis in a Centrosymmetric CuII Complex Induced by Lattice Water Molecules − Crystal and Molecular Structures of Bis[bis(3,5‐dimethylpyrazol‐1‐yl)acetato]copper(II) and Its Dihydrate
Authors: Kozlevčar Bojan , Gamez Patrick , de Gelder René , Driessen Willem L. , Reedijk Jan
Published: December 2002

Two copper coordination compounds with the tridentate (NON) ligand bis(3,5‐dimethylpyrazol‐1‐yl)acetic acid (Hbdmpza) are reported. The central coordination sphere in both compounds is fulfilled by two ligands in [CuL2]. The ligands are centrosymmetrically oriented around the copper ion, thus forming a trans‐CuN4O2 elongated octahedral chromophore. The atoms in both compounds are not positioned at the same places in the Jahn−Teller‐distorted octahedral environment. For compound [CuL2] (1) two nitrogen atoms are located on the longer axis [Cu−N: 2.438(2) Å], while the other two nitrogen atoms [Cu−N: 2.006(2) Å] and the two oxygen atoms [Cu−O: 1.983(2) Å] form the basal plane of the octahedron. The coordination sphere for [CuL2]·2H2O (2) is composed of four nitrogen atoms [Cu−N: 2.013(3), 2.038(2) Å] that form the basal plane, while the two oxygen atoms are at a longer distance [Cu−O: 2.293(2) Å]. The water molecules in 2 are hydrogen bonded to the non‐coordinated carboxylate oxygen atoms, forming bridges between two neighbouring monomeric units and leading to an infinite chain. Significant differences are observed for both compounds by spectroscopic investigations (EPR, IR, ligand field). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Unexpected Formation of a Novel Fluorinated Triene
Authors: Shevchenko Igor , Andrushko Vasyl , Lork Enno , Röschenthaler Gerd‐Volker
Published: December 2002

Bis[bis(dialkylamino)phosphanyl]methane (1) and 4,4,4‐trifluoro‐3‐(trifluoromethyl)‐2‐butenenitrile (2) unexpectedly gave triene 3. According to the X‐ray structure analysis compound 3 exists in the solid state exclusively as one isomer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Unique Magnetic Behavior in a One‐Dimensional Coordination Polymer [Co(tmpyim)2(tp)]
Authors: Li Licun , Liu Zhiliang , Turner Scott S. , Liao Daizheng , Jiang Zonghui , Yan Shiping
Published: December 2002

A one dimensional cobalt(II)−radical complex [Co(tmpyim)2(tp)] [tmpyim = 4,4,5,5‐tetramethyl‐2‐(3′‐pyridyl)imidazoline‐1‐oxyl 3‐oxide and tp = terephthalate dianion] has been synthesized and characterized by X‐ray crystallography. The crystal structure consists of infinite chains of Co(tmpyim)2 units cross‐linked by terephthalate ligands. The magnetic behavior of the complex is unique and is discussed in connection with the crystal structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Structure of Some Amine Solvates of Magnesium Bis(tetrahydroborate) and DFT Calculations on Solvates of Lithium Tetrahydroborate
Authors: Bremer Mathias , Nöth Heinrich , Warchhold Marcus
Published: December 2002

Eight solvates of magnesium bis(tetrahydroborate) have been prepared and characterised by NMR and IR spectroscopy, and five of them also by X‐ray crystallography. Compounds Mg(BH4)2·3NH2tBu and Mg(BH4)2·3pip each have a distorted trigonal‐bipyramidal structure (with the BH4 group viewed as a simple ligand) while the putative Mg(BH4)2·6py proved to be [Mg(BH4)2·4py] with a pseudooctahedral structure, two py molecules being present as solvent of crystallization. Similarly, Mg(BH4)2·8DMSO contains the cation [Mg(DMSO)6]2+ in the crystal, and Mg(BH4)2·6NH2Bzl has an ionic lattice made up of Mg(NH2Bzl)62+ and BH4− ions. The BH4 groups in the molecular compounds are bonded to the Mg centre through double hydrogen bonds. In order to study the bonding in alkali and alkali earth metal tetrahydroborates, DFT calculations were performed for LiBH4 and its ammonia and dimethyl ether solvates. The minimum‐energy structure for a LiBH4 molecule has C3v symmetry; this is not changed when one ammonia molecule is added and is also the result for LiBH4·3NH3. Addition of the first NH3 or Me2O molecule contributes more to the stabilisation than a second or a third molecule. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Coordination Modes of 9‐Methyladenine in cis‐Platinum(II) Complexes with Dimethyl(phenyl)phosphanes as Ancillary Ligands − Synthesis and Characterization of cis‐[PtL2(9‐MeAd)2](NO3)2, cis‐[PtL2{9‐MeAd(−H)}]3(NO3)3, and cis‐[L2Pt{9‐MeAd(−H)}PtL2](NO3)3
Authors: Longato Bruno , Pasquato Lucia , Mucci Adele , Schenetti Luisa
Published: December 2002

Treatment of 9‐methyladenine (9‐MeAd) with cis‐[PtL2(NO3)2] (1) (L = PMe2Ph) in a 2:1 molar ratio generated the bis(adduct) cis‐[PtL2(9‐MeAd)2](NO3)2 (2), which was isolated and fully characterized by multinuclear (1H, 31P, 13C, 195Pt and 15N) NMR analysis, which showed that the two nucleobases are selectively coordinated through the N1 atom. Small amounts of a mono(adduct) cis‐[PtL2(S)(9‐MeAd)]2+ (3) (S = solvent) and of a diplatinated species cis‐[L2Pt(S){9‐MeAd(−H)}PtL2]3+ (4) are formed in DMSO solution when 9‐MeAd is present in smaller quantities than 1. Complex 3 is platinated at N1, with a solvent molecule representing the fourth ligand around the metal center. Complex 4 contains an adenine molecule deprotonated and platinated at N1,N6,N7, with two cis‐L2Pt units bonded to nitrogen atom N1 and to nitrogen atoms N6 and N7, respectively. With increasing relative concentration of the nucleobase, both complexes 3 and 4 progressively convert into the bis(adduct) 2, the only species detectable in solution when the Ad/Pt molar ratio is 2:1. The trinuclear compound cis‐[L2Pt{9‐MeAd(−H)}]3(NO3)3 (5) (L = PMe2Ph), containing an NH2‐deprotonated nucleobase bridging the metal centers through the N1 and N6 atoms, is quantitatively formed when the dinuclear hydroxo complex cis‐[Pt(μ‐OH)L2]2(NO3)2 (6) reacts with 9‐MeAd in CH3CN solution. The isolated complex was fully characterized by multinuclear NMR spectroscopy and mass spectrometry. It appears to be stable in solution in CH3CN and chlorinated solvents, whereas in DMSO it partially converts into a new species, probably the dinuclear analog cis‐[PtL2{9‐MeAd(−H)}]2(NO3)2, in which the adenine maintains its coordination mode. At equilibrium the trinuclear/dinuclear species molar ratio is 20:1. Through the addition of a stoichiometric amount of nitrate 1 to a DMSO solution of 5 we were able to generate the diplatinated compound 4 in high yield. Complex 4 displays a new coordination mode for the adeninate ion, with N1 bonded to one platinum atom whereas N6 and N7 are chelated to a second one. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Chelation versus Cyclometalation in a Cationic Dppn−RhI Complex − A Unique Rearrangement of Norbornadiene via C−H Activation of the Pyridazine Ring
Authors: Dorta Reto , Konstantinovski Leonid , Shimon Linda J. W. , Ben‐David Yehoshoa , Milstein David
Published: December 2002

The tetradentate ligand 3,6‐bis(2‐pyridyl)pyridazine (dppn) was treated with cationic RhI precursors. The mononuclear complexes [Rh(dppn)(NBD)]BF4 (1) and [Rh(dppn)(COD)]BF4 (5) were obtained in quantitative yield when treating dppn with [Rh(NBD)2]BF4 or [Rh(COD)2]BF4 respectively. Treatment of 1 with a second equivalent of the metal precursor [Rh(NBD)(CH3CN)2]BF4 led to the dinuclear complex [Rh2(dppn‐H)(NBD)(η1‐C7H9)(CH3CN)2](BF4)2 (2) [dppn‐H = μ‐C4HN2(C5H4N)2‐3,6], a mixed RhI−RhIII complex. This complex arises from C−H activation of the pyridazine ring, followed by a unique rearrangement of the NBD ligand. Compound 2 was also obtained directly by treating dppn with 2 equiv. of [Rh(NBD)(CH3CN)2]BF4. The complex [Rh2(dppn‐H)(NBD)(η1‐C7H9)(CH3OH)2(CH3CN)](BF4)2 (4) was obtained by dissolving 2 in methanol. Full characterization of compounds 1, 4 and 5 included an investigation by 1H‐15N GHMBC NMR spectroscopy and single‐crystal X‐ray structures of 1 and 4. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2003)
The Ambivalent Bonding of the 3(5)‐Isopropylpyrazolyl Moiety in Homo‐ and Heteroscorpionate Hydrobis(3‐R1‐5‐R2‐pyrazolyl)(y‐isopropylpyrazolyl)boratocobalt(II) Complexes (y = 3 or 5)
Authors: Ruman Tomasz , Ciunik Zbigniew , Wołowiec Stanisław
Published: December 2002

The synthesis of hydrotris(pyrazol‐1‐yl)borate ligands (Tpx) by condensation of sodium borohydride with 3(5)‐isopropylpyrazole and either 5(3)‐methyl‐3(5)‐phenylpyrazole or 3,5‐diphenylpyrazole gave the novel heteroscorpionate ligands hydrobis(5‐methyl‐3‐phenylpyrazolyl)(5‐isopropylpyrazolyl)borate and hydrobis(3,5‐diphenylpyrazolyl)(5‐isopropylpyrazolyl)borate, respectively. These were converted into CoTpx(NCS) complexes as well as CoTpx2 in the case of the former ligand. In an attempted synthesis of heteroscorpionates bearing two y‐isopropylpyrazolyl moieties (y = 3 or 5) formation of the homoscorpionate hydrotris(3‐isopropylpyrazolyl)borate along with the above‐mentioned heteroscorpionates was noticed; no formation of the desired heteroscorpionates could be detected. The bis[hydrobis(5‐methyl‐3‐phenylpyrazolyl)(5‐isopropylpyrazolyl)borato]cobalt(II) and tetrahydrofuranothiocyanatobis[hydrobis(5‐methyl‐3phenylpyrazolyl)(5‐isopropylpyrazolyl)borato]cobalt(II) tetrahydrofuran solvate complexes were studied by X‐ray crystallography. Two Tpx ligands provide six nitrogen donors from pyrazol‐1‐yl residues to form a Tpx2Co complex in which two 5‐isopropylpyrazolyl rings are placed in a plane of symmetry, whereas the same Tpx ligand is bound in an η3 fashion in the pentacoordinate [CoTpx(NCS)(THF)]·THF complex, in which a nitrogen atom from thiocyanate and an oxygen atom from THF complete the coordination sphere of the central metal ion. These compounds as well as the complexes thiocyanatohydrobis(3,5‐diphenylpyrazolyl)(5‐isopropylpyrazolyl)boratocobalt(II) and thiocyanatohydrotris(3‐isopropylpyrazolyl)boratocobalt(II) were characterized by 1H NMR and IR spectroscopy. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2003)
Two New Zeolite‐Like Supramolecular Copper Complexes
Authors: Sun Daofeng , Cao Rong , Sun Yanqiong , Li Xing , Bi Wenhua , Hong Maochun , Zhao Yingjun
Published: December 2002

Assembly of sodium 5‐sulfoisophthalate (NaH2SIPA) with copper(II) nitrate in the presence of an amine results in the formation of two new types of supramolecular copper complexes [{Cu(H2O)2(HSIPA)}·2H2O·(PIP)1/2]n (1) and [{Cu(H2O)3(HSIPA)}·6H2O·(hmt)1/2]n (2). Both complexes have 1D zigzag chain structures formed by the interconnection of four‐ or five‐coordinate copper ions by carboxylate ligands. The 3D supramolecular architectures are dependent on the guest amine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Tripodal Phosphane Ligands with Novel Linker Units and Their Rhodium Complexes as Building Blocks for Dendrimer Catalysts
Authors: Findeis Ralf A. , Gade Lutz H.
Published: December 2002

An efficient strategy for the backbone functionalization of a tripodal phosphane ligand which allows its attachment to solid supports and polymers has been developed. Using pentaerythrol (1) as the starting material, the functionalized phosphane tripod HOCH2CH2OCH2C(CH2PPh2)3 (9) was obtained in good yield in a four‐step synthesis. Reaction of 9 with [Mo(CO)3(MeCN)3] and [Rh(COD)2][A] gave the complexes [{HOCH2CH2OCH2C(CH2PPh2)3}Mo(CO)3] (10) and [{HOCH2CH2OCH2C(CH2PPh2)3}Rh(COD)][A] (A = BF4: 11a, PF6: 11b), respectively, two of which were characterised by X‐ray diffraction. The carbosilane dendrimer Si{(CH2)3SiMe2Cl}4 “G[0]‐[Cl]4” (12) and its first generation analogue Si[(CH2)3SiMe{(CH2)3SiMe2Cl}2]4 “G[1]‐[Cl]8” (15) were reacted with, respectively, four and eight molar equivalents of the lithium alkoxy derivative of 9 giving the two functionalized dendrimers G[0]‐[OCH2CH2Otriphos]4 (13) and G[1]‐[OCH2CH2Otriphos]8 (16). These were metallated with four and eight molar equivalents of [Rh(COD)2][BF4] in CH2Cl2, selectively yielding the metallated dendrimers G[0][OCH2CH2OtriphosRh(COD)BF4]4 (14) and G[1]‐[OCH2CH2OtriphosRh(COD)BF4]8 (17). Comparative catalytic hydrogenation of styrene and 1‐hexene using [Rh(triphos)(COD)][BF4] (11a) and the metallodendrimers 14 and 17 showed that the fixation to the low generation dendrimers did not alter the catalytic hydrogenation properties of the catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Triorganotin Fluoride Structures: A Ligand Close‐Packing Model with Predominantly Ionic Sn−F Bonds
Authors: Beckmann Jens , Horn Dagmar , Jurkschat Klaus , Rosche Fred , Schürmann Markus , Zachwieja Uwe , Dakternieks Dainis , Duthie Andrew , Lim Allan E. K.
Published: December 2002

The synthesis and complete characterization by multinuclear NMR, infrared, and Mössbauer spectroscopy, by single crystal X‐ray analysis, as well as by electrospray mass spectrometry of the new soluble triorganotin fluoride Me2PhSnF (1) is reported. The crystal structure of 1 reveals a rod‐like polymeric structure in the solid state. Solutions of 1 in apolar solvents, such as toluene, contain mixtures of interconvertible oligomers. Ab initio MO calculations on model compounds H3SnF, [H3SnFSnH3]+, and [FH3SnFSnH3F]− indicate that the Sn−F bonds are substantially ionic in character, and suggest open‐chain species, rather than cyclic species. In donor solvents, such as pyridine, 1 forms complexes with the solvent, such as Me2PhSnF·pyridine. The solid‐state structure of (Me3SiCH2)3SnF (2) is reformulated as monomeric with a weak intermolecular Sn···F interaction that gives rise to a [4+1] coordination. The relative short Sn−Sn separation enables the fluorine atoms to oscillate (flip‐flop) between two neighboring (Me3SiCH2)3Sn− groups, which is expressed in the X‐ray experiment by a dynamic disorder. Ab initio MO calculations on a model compound, [H3SnFSnH3]+, suggest only a small energy barrier for the flip‐flop motion. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2003)
Cover Picture
Authors: Dorta Reto , Konstantinovski Leonid , Shimon Linda J. W. , Ben‐David Yehoshoa , Milstein David
Published: December 2002

The cover picture shows the structure of an unusual dinuclear RhI−RhIII complex obtained in the reaction of the tetradentate ligand 3,6‐bis(2‐pyridyl)pyridazine with cationic (diene)RhI precursors. Initially, the expected N,N‐bidentate RhI complex is formed, which upon further reaction with the RhI precursor undergoes C−H bond activation of the pyridazine ring, forming a C,N‐bidentate RhIII center. This is followed by a unique rearrangement of the diene, which is dependent on the metal precursor and on the ligand used. Details are discussed in the article by D. Milstein et al. on p. 70 ff. We thank Relli Mahager (Graphics Department, WIS) for producing the colour picture.
Electrochemical Sensors Based on Carbon Nanotubes
Authors: Zhao Qiang , Gan Zhenhai , Zhuang Qiankun
Published: December 2002

Carbon nanotubes are attractive new materials. It has been about a decade since carbon nanotubes were discovered. Carbon nanotubes have many outstanding properties and have many practical or potential applications. In this short review we introduce recent advances in carbon nanotubes as potential material for electrochemical sensors. The advantages of carbon nanotubes as sensors are discussed along with future prospects.
Batch Injection Analysis Utilizing Modified Electrodes with Tetraruthenated Porphyrin Films for Acetaminophen Quantification
Authors: Quintino Maria S. M. , Araki Koiti , Toma Henrique E. , Angnes Lúcio
Published: December 2002

Batch injection analysis (BIA) utilizing amperometric detection with glassy carbon electrodes modified with [Co(TPyP){Ru(bipy)2Cl}4](TFMS)5⋅H2O porphyrin films were explored for acetaminophen analysis in pharmaceutical formulations. BIA is an interesting alternative for application of electrodes modified with tetraruthenated porphyrins. This sensor exhibited sharp current response peaks, rapid washout and excellent reproducibility for BIA‐amperometric quantification of acetaminophen. Also, a wide linear working range (10−4 to 10−6 mol L−1) as well as high sensitivity and sampling frequency rate (detection limit=1.1×10−7 mol L−1, sampling frequency=120 injections/h) and a small volume of analysis (100 μL/injection) was achieved. Furthermore, the proposed method permits the direct quantification of acetaminophen in many pharmaceutical products, avoiding cumbersome processes as previous separations, solvent extraction or sample filtration. The new procedure was applied to the analysis of commercial pharmaceutical products and the results were in excellent agreement with the ones obtained by spectrophotometric method. Accordingly, this amperometric method showed to be very well suited for quality control analysis and other applications with similar requirements.
Electrochemical Studies for the Interaction of DNA with an Irreversible Redox Compound – Hoechst 33258
Authors: Sufen Wang , Tuzhi Peng , Yang Catherine F.
Published: December 2002

An electrochemical equation suitable for examining the interaction of irreversible redox compounds with DNA is established. According to the equation, diffusion coefficients of both free and binding compounds (Df , Db), binding constant (K) and binding site size (s) of compounds with DNA could be obtained simultaneously by nonlinear fit analysis of electrochemical data. Bis‐benzimidazole derivative (Hoechst 33258), as an irreversible redox compound, was investigated for its electrochemical behavior and the interaction with natural fish sperm DNA (fsDNA) using cyclic voltammetry, chronocoulometry, bulk electrolysis and scanning electrochemical microscope technique. A nonlinear fit analysis of the experimental data yielded: Df=8.3×10−5 cm2 s−1, Db=6.0×10−6 cm2 s−1, K=2.1×108 cm3 mol−1, s=3.9. The overall results suggest that Hoechst 33258 binds tightly to the minor groove of fsDNA and covers four base pairs.
Mixed Aza‐Thioether Crowns Containing a 1,10‐Phenanthroline Sub‐Unit as Neutral Ionophores for Silver Ion
Authors: Shamsipur Mojtaba , Javanbakht Mehran , Ganjali Mohammad Reza , Mousavi Mir Fazlollah , Lippolis Vito , Garau Alessandra
Published: December 2002

Three different recently synthesized aza‐thioether crowns containing a 1,10‐phenanthroline sub‐unit (L1–L3) and a corresponding acyclic ligand (L4) were studied to characterize their abilities as silver ion ionophores in PVC‐membrane electrodes. Novel conventional silver‐selective electrodes with internal reference solution (CONISE) and coated graphite‐solid contact electrodes (SCISE) were prepared based on one of the 15‐membered crowns containing two donating S atoms and two phenanthroline‐N atoms (L1). The electrodes reveal a Nernstian behavior over wide Ag+ ion concentration ranges (1.0×10−5−1.0×10−1 M for CONISE and 5.0×10−8−4.0×10−2 M for SCISE) and very low limits of detection (8.0×10−6 M for CONISE and 3.0×10−8 M for SCISE). The potentiometric response is independent from pH of the solution in the pH range 3.0–8.0. The electrodes manifest advantages of low resistance, very fast response and, most importantly, good selectivities relative to a wide variety of other cations. The electrodes can be used for at least 2 months (for CONISE) and 4 months for (SCISE) without any appreciable divergence in potentials. The electrodes were used as an indicator electrode in the potentiometric titration of Ag+ ion and in the determination of silver in photographic emulsions and in radiographic and photographic films.