bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Photoactivated DNA Oxidizing Agents: Synthesis and Study of Photophysical Properties and DNA Interactions of Novel Viologen‐Linked Acridines
Authors: Joseph Joshy , Eldho Nadukkudy V. , Ramaiah Danaboyina
Published: December 2003

A new series of photoactivated DNA oxidizing agents in which an acridine moiety is covalently linked to viologen by an alkylidene spacer was synthesized, and their photophysical properties and interactions with DNA, including DNA cleaving properties, were investigated. The fluorescence quantum yields of the viologen‐linked acridines were found to be lower than that of the model compound 9‐methylacridine (MA). The changes in free energy for the electron transfer reactions were found to be favorable, and the fluorescence quenching observed in these systems is explained by an electron transfer mechanism. Intramolecular electron transfer rate constants were calculated from the observed fluorescence quantum yields and singlet lifetime of MA and are in the range from 1.06×1010 s−1 for 1 a (n=1) to 6×108 s−1 for 1 c (n=11), that is, the rate decreases with increasing spacer length. Nanosecond laser flash photolysis of these systems in aqueous solutions showed no transient absorption, but in the presence of guanosine or calf thymus DNA, transient absorption due to the reduced viologen radical cation was observed. Studies on DNA binding demonstrated that the viologen‐linked acridines bind effectively to DNA in both intercalative and electrostatic modes. Results of PM2 DNA cleavage studies indicate that, on photoexcitation, these molecules induce DNA damage that is sensitive to formamidopyrimidine DNA glycosylase. These viologen‐linked acridines are quite stable in aqueous solutions and oxidize DNA efficiently and hence can be useful as photoactivated DNA‐cleaving agents which function purely by the co‐sensitization mechanism.
Novel Podands and Macrocycles with Diacetal (Tetraoxadecalin) Cores: Synthesis, Structure, Stereochemistry and Cation Inclusion
Authors: Abramson Sarah , Ashkenazi Eli , Frische Klaus , Goldberg Israel , Golender Larisa , Greenwald Moshe , Lemcoff N. Gabriel , Madar Ravit , Weinman Sarah , Fuchs Benzion
Published: December 2003

A series of functionalized 2,6‐dialkyl‐cis‐1,3,5,7‐tetraoxadecalin podands (3–10, alkyl = hydroxy‐, mesyloxy‐, halo‐, azido‐ and aminomethyl and ‐ethyl) were prepared, characterized, and used as precursors for a new and interesting class of macrocycles and cryptands (12–21), with the aim to use these as host–guest inclusion systems. Extensive spectroscopic work was performed, structural endorsement was obtained from X‐ray diffraction analyses and further insight into the structures was obtained from theoretical/computational studies. A number of macrocycles in the series exhibited good complexation with alkaline‐earth metal ions.
Quantitative Chirality Analysis of Molecular Subunits of Bis(oxazoline)copper(II) Complexes in Relation to Their Enantioselective Catalytic Activity
Authors: Alvarez Santiago , Schefzick Sabine , Lipkowitz Kenny , Avnir David
Published: December 2003

The analysis of the quantitative chirality of molecular subunits of spirocyclic bisoxazoline copper complexes was carried out in order to identify the molecular portions most responsible for the chirality of the whole molecule, and therefore also for its catalytic enantioselectivity. It is shown that the smallest fragment that carries the information on molecular chirality contains only a portion of the bidentate bisoxazoline ligands and most atoms of the two monodentate ligands. The structural parameters that are best correlated to the chirality measures of the studied systems are the bond angles at the bridgehead spiro‐carbon atom. A prediction is made for an analogous catalyst with potentially high enatioselectivity.
Au Nanoparticle‐Enhanced Surface Plasmon Resonance Sensing of Biocatalytic Transformations
Authors: Zayats Maya , Pogorelova Svetlana P. , Kharitonov Andrei B. , Lioubashevski Oleg , Katz Eugenii , Willner Itamar
Published: December 2003

N‐(3‐Aminopropyl)‐N′‐methyl‐4,4′‐bipyridinium is coupled to tiopronin‐capped Au nanoparticles (diameter ca. 2 nm) to yield methyl(aminopropyl)viologen‐functionalized Au nanoparticles (MPAV2+‐Au nanoparticles). In situ electrochemical surface plasmon resonance (SPR) measurements are used to follow the electrochemical deposition of the bipyridinium radical cation modified Au nanoparticles on an Au‐coated glass surface and the reoxidation and dissolution of the bipyridinium radical cation film. The MPAV2+‐functionalized Au nanoparticles are also employed for the amplified SPR detection of NAD+ and NADH cofactors. By SPR monitoring the partial biocatalyzed dissolution of the bipyridinium radical cation film in the presence of diaphorase (DP) NAD+ is detected in the concentration range of 1×10−4 M to 2×10−3 M. Similarly, the diaphorase‐mediated formation of the bipyridinium radical cation film on the Au‐coated glass surface by the reduction of the MPAV2+‐functionalized Au nanoparticles by NADH is used for the amplified SPR detection of NADH in the concentration range of 1×10−4 M to 1×10−3 M.
Diferratricarbaboranes of the subcloso‐[(η5‐C5H5)2Fe2C3B8H11] Type, the First Representatives of the 13‐Vertex Dimetallatricarbaborane Series
Authors: Grüner Bohumír , Štíbr Bohumil , Kivekäs Raikko , Sillanpää Reijo , Stopka Pavel , Teixidor Francesc , Viñas Clara
Published: December 2003

Treatment of the [2‐Cp‐9‐tBuNH‐closo‐2,1,7,9‐FeC3B8H10] (1) ferratricarbollide (Cp = η5‐C5H5−) with Na+ C10H8− in 1,2‐dimethoxyethane (DME) at room temperature produced an air‐sensitive transient anion with a tentatively identified nido‐[tBuNH‐CpFeC3B8H10]2− constitution. In‐situ reaction of this low‐stability ion with [CpFe(CO)2I] or [CpFe(CO)2]2 generated three violet diferratricarbaboranes identified as paramagnetic subcloso complexes [4,5‐Cp2‐‐4,5,1,6,7‐Fe2C3B8H11] (2; yield 2 %), [4,5‐Cp2‐‐4,5,1,7,12‐Fe2C3B8H11] (3; yield 2 %), and [7‐tBuNH‐4,5‐Cp2‐‐4,5,1,7,12‐Fe2C3B8H10] (4; yield 14 %). These first representatives of the 13‐vertex dimetallatricarbaborane family were characterized by EPR and IR spectroscopy, and mass spectrometry, and their structures were determined by X‐ray diffraction analysis.
Synthesis and Inhibition Properties of Conformational Probes for the Mutase‐Catalyzed UDP‐Galactopyranose/Furanose Interconversion
Authors: Caravano Audrey , Mengin‐Lecreulx Dominique , Brondello Jean‐Marc , Vincent Stéphane P. , Sinaÿ Pierre
Published: December 2003

UDP‐galactose mutase is a flavoenzyme that catalyzes the isomerization of UDP‐galactopyranose into UDP‐galactofuranose, a key step in the biosynthesis of important bacterial oligosaccharides. Several mechanisms for this unique ring‐contraction have been proposed, one of them involving a putative 1,4‐anhydrogalactopyranose as an intermediate in the reaction. The purpose of this study was to probe the mutase binding site with conformationally restricted analogues of its substrate. Thus, we describe the straightforward synthesis of two C‐glycosidic UDP‐galactose derivatives: analogue 1, presenting a galactose moiety locked in a bicyclic 1,4B boat conformation, and UDP‐C‐Galf 2, where the galactose residue is locked in the conformation of the mutase substrate. The two molecules were found to be inhibitors of UDP‐galactose mutase at levels depending on the redox state of the enzyme. Strong inhibition of the native enzyme, but a low one of the reduced mutase, were observed with UDP‐C‐Galf 2, whereas 1 displayed intermediate inhibition levels under both native and reducing conditions. These data provide evidence of a significant conformational difference of the mutase binding pocket in the reduced enzyme and in the native one, the enzyme switching from a low Galf‐affinity state (reduced enzyme) to a very strong one (native enzyme). It is remarkable that the mutase binds the boat‐locked analogue 1 with similar affinities in both its conformational states. These results support a mechanism involving the formation of 1,4‐anhydrogalactopyranose as a low‐energy intermediate. An alternative explanation would be that the distortion of the galactose moiety during the cycle contraction transiently brings the carbohydrate into a conformation close to a 1,4B boat.
Reduction of Benzophenone and 9(10H)‐Anthracenone with the Magnesium Complex [(2,6‐iPr2C6H3‐bian)Mg(thf)3]
Authors: Fedushkin Igor L. , Skatova Alexandra A. , Cherkasov Vladimir K. , Chudakova Valentina A. , Dechert Sebastian , Hummert Markus , Schumann Herbert
Published: December 2003

The reduction of benzophenone with the magnesium complex [(2,6‐iPr2C6H3‐bian)Mg(thf)3] (1), containing the 1,2‐bis[(2,6‐diisopropylphenyl)imino]acenaphthene dianion, affords the pinacolato complex [(2,6‐iPr2C6H3‐bian)Mg(thf)]2[μ‐O2C2Ph4]⋅(C6H6)4 (2). The reaction of 1 with 9(10H)‐anthracenone yields the 9‐anthracenolato complex [(2,6‐iPr2C6H3‐bian)Mg(OC14H9)(thf)2] (3). Complexes 2 and 3 were characterized by elemental analyses, UV/Vis, IR, and ESR spectroscopy, as well as by single crystal X‐ray diffraction. Complex 2 dissociates in solution with splitting of the bridging pinacolato unit, forming the biradical diimino/ketyl complex [(2,6‐iPr2C6H3‐bian)Mg(thf)(OCPh2)].
Ruthenium‐Catalyzed Chemoselective N‐Allyl Cleavage: Novel Grubbs Carbene Mediated Deprotection of Allylic Amines
Authors: Alcaide Benito , Almendros Pedro , Alonso Jose M.
Published: December 2003

A novel application of the Grubbs carbene complex has been discovered. The first examples of the catalytic deprotection of allylic amines with reagents other than palladium catalysts have been achieved through Grubbs carbene mediated reaction. Significantly, the catalytic system directs the reaction toward the selective deprotection of allylic amines (secondary as well as tertiary) in the presence of allylic ethers. A variety of substrates, including enantiomerically pure multifunctional piperidines, are also usable. The new method is more convenient, chemoselective, and operationally simple than the palladium‐catalyzed method. The current mechanistic hypothesis invokes a nitrogen‐assisted ruthenium‐catalyzed isomerization, followed by hydrolysis of the enamine intermediate. We believe that the reactive species involved in the reaction may be an RuH species rather than the Grubbs carbene itself. Thus, the isomerization may occur according to the hydride mechanism. The synthetic utility of this ruthenium‐catalyzed allyl cleavage is illustrated by the preparation of indolizidine‐type alkaloids.
SSZ‐53 and SSZ‐59: Two Novel Extra‐Large Pore Zeolites
Authors: Burton Allen , Elomari Saleh , Chen Cong‐Yan , Medrud Ronald C. , Chan Ignatius Y. , Bull Lucy M. , Kibby Charles , Harris Thomas V. , Zones Stacey I. , Vittoratos E. Steven
Published: December 2003

The syntheses, structure solutions, and physicochemical and catalytic characterizations of the novel zeolites SSZ‐53 and SSZ‐59 are described. SSZ‐53 and SSZ‐59 were synthesized under hydrothermal conditions with the [1‐(4‐fluorophenyl)cyclopentylmethyl]trimethyl ammonium cation and 1‐[1‐(4‐chlorophenyl)cyclopentylmethyl]‐1‐methyl azocanium cation, respectively, as structure‐directing agents. The framework topology of SSZ‐53 was solved with the FOCUS method, and the structure of SSZ‐59 was determined by model building. Rietveld refinement of synchrotron X‐ray powder diffraction data confirms each proposed model. SSZ‐53 and SSZ‐59 each possess a one‐dimensional channel system delimited by 14‐membered rings. Results from transmission electron microscopy, electron diffraction, catalytic experiments (spaciousness index and constraint index tests), and argon and hydrocarbon adsorption experiments are consistent with the proposed structures.
Separated and Aligned Molecular Fibres in Solid State Self‐Assemblies of Cyclodextrin [2]Rotaxanes
Authors: Onagi Hideki , Carrozzini Benedetta , Cascarano Giovanni L. , Easton Christopher J. , Edwards Alison J. , Lincoln Stephen F. , Rae A. David
Published: December 2003

The conformations of two [2]rotaxanes, each comprising α‐cyclodextrin as the rotor, a stilbene as the axle and 2,4,6‐trinitrophenyl substituents as the capping groups, have been examined in solution and in the solid state, using 1H NMR spectroscopy and X‐ray crystallography, respectively. In solution, introducing substituents onto the stilbene prevents the cyclodextrin from being localized over one end of the axle. Instead the cyclodextrin moves back and forth along the substituted stilbene. In the solid state, the axles of the rotaxanes form extended molecular fibres that are separated from each other and aligned along a single axis. The molecular fibres are strikingly similar to those formed by the axle component of one of the rotaxanes in the absence of the cyclodextrin, but in the latter case they are neither separated nor all aligned.
Installation of a Ratchet Tooth and Pawl To Restrict Rotation in a Cyclodextrin Rotaxane
Authors: Onagi Hideki , Blake Christopher J. , Easton Christopher J. , Lincoln Stephen F.
Published: December 2003

Eight new [2]rotaxanes have been prepared, incorporating an α‐cyclodextrin as the rotor, a stilbene as the axle, and trinitrophenyl substituents as capping groups. Strategies have been devised to elaborate these by linking the rotor to the axle, to produce two new [1]rotaxanes. Rotational motion in a selection of these rotaxanes has been investigated through the application of two‐dimensional NMR spectroscopy by performing TOCSY, DQF‐COSY, ROESY and HMQC experiments. This has shown that a methoxyl group incorporated on the stilbene and a succinamide joining the stilbene and the cyclodextrin behave analogously to a ratchet tooth and pawl, respectively, to restrict rotation.
Fragmentation of Carbohydrate Anomeric Alkoxy Radicals: A New Synthesis of Chiral 1‐Halo‐1‐iodo Alditols
Authors: González Concepción C. , Kennedy Alan R. , León Elisa I. , Riesco‐Fagundo Concepción , Suárez Ernesto
Published: December 2003

Treatment of 1,2‐fluorohydrins, 1,2‐chlorohydrins, 1,2‐bromohydrins, and 1,2‐iodohydrins of the D‐gluco, D‐galacto, D‐lacto, L‐rhamno, D‐allo, L‐arabino, 3‐deoxy‐D‐gluco, and 3,4‐dideoxy‐D‐gluco families of carbohydrates with the (diacetoxyiodo)benzene/iodine system afforded 1‐fluoro‐1‐iodo, 1‐chloro‐1‐iodo, 1‐bromo‐1‐iodo, and 1,1‐diiodo alditols, respectively, in excellent yields. The reaction was achieved by radical fragmentation of the C1C2 bond, triggered by the initially formed anomeric alkoxy radical, and subsequent trapping of the C2‐radical by iodine atoms. This methodology is compatible with the stability of the protective groups most frequently used in carbohydrate chemistry. The potential utility of these 1‐halo‐1‐iodo alditols as chiral synthons was evaluated by their transformation into alk‐1‐enyl iodides and in the Takai E‐olefination reaction.
Cover Picture: SSZ‐53 and SSZ‐59: Two Novel Extra‐Large Pore Zeolites (Chem. Eur. J. 23/2003)
Authors: Burton Allen , Elomari Saleh , Chen Cong‐Yan , Medrud Ronald C. , Chan Ignatius Y. , Bull Lucy M. , Kibby Charles , Harris Thomas V. , Zones Stacey I. , Vittoratos E. Steven
Published: December 2003

The cover picture shows two three‐dimensional models of the novel extra‐large pore zeolites SSZ‐53 (top) and SSZ‐59 (bottom), prepared and characterized by the researchers at ChevronTexaco. For more details see the article by A. Burton, S. Elomari, et al. on p. 5737 ff.
Materialfeuchtigkeitsbestimmung in Biofiltern mit Hilfe des Leitfähigkeitsmessverfahrens
Authors: Kapfenberger J. , Kabasci S. , Kümmel R. , Fahlenkamp H.
Published: December 2003

No abstracts.
Einsatz von T‐Verzweigungen als Flüssigkeitsabscheider in Zweiphasenströmungen
Authors: Hirsch T.
Published: December 2003

No abstracts.
Haftkraftverteilungen von rauen Haftsystemen am Beispiel Kugel–Platte
Authors: Götzinger M. , Peukert W.
Published: December 2003

No abstracts.
Zerkleinerung nicht‐spröder Stoffe in Rotorscheren
Authors: Woldt D. , Schubert G. , Jäckel H.‐G.
Published: December 2003

No abstracts.
Naturfarbstoffe: Farben mit Geschichte
Authors: Struckmeier Sabine
Published: December 2003

Bis zur Einführung und industriellen Nutzung der synthetischen Farbstoffe wurde mit Naturfarbstoffen wie Waid, Purpur, Krapp gefärbt. Die grundlegenden Gesetzmäßigkeiten dieser Küpen‐, Direkt‐ und Beizenverfahren werden noch heute in der modernen Färberei genutzt. Der Beitrag gibt einen Einblick in die kulturellen und historischen Zusammenhänge bei der Entwicklung der Textilherstellung und der Färberei vom Handwerk zum Vorläufer der modernen Industrie. Am Beispiel der Krappfärbung wird der Einfluss von Beizmitteln auf den Farbausfall dargestellt.
Justus Liebig trifft Georg Büchner: Sturm und Dung — eine fiktive Begegnung
Authors: Leggewie Claus
Published: December 2003

In einer fiktiven Begegnung zwischen dem Chemiker und Agrarreformer Justus Liebig und dem Dichter und Sozialrevolutionär Georg Büchner in Gießen im Jahr 1833 werden Weichenstellungen in der Vormärz‐Zeit dargestellt und aktuelle Bezüge zur heutigen Lebensmittelchemie hergestellt.
Alle Jahre wieder: die Chemie der Weihnachtskerze
Authors: Roth Klaus
Published: December 2003

Wenn wir am Heiligen Abend die Kerzen entzünden, treiben wir ein Stück besonders schöner, aber auch besonders komplexer Chemie. Von der im Inneren der strahlenden Kerzenflamme ablaufenden Chemie haben wir nur ungefähre Vorstellungen, viele Details sind uns noch verborgen. Klar ist jedoch, dass letztlich glühende Rußpartikel unseren Wohnstuben den festlichen Glanz verleihen. Im Weltraum sähe es ganz anders aus: die molekularen Exoten C2* und CH* würden mit ihrem kaum sichtbaren, blassblauen Licht unsere Augen wohl kaum zum Leuchten bringen. Ist es nicht wunderbar, dass die Chemie der Kerze für unsere irdischen Wohnzimmer optimiert ist? In diesem Sinne: Fröhliche Weihnachten!
Preisverdächtiger Kernspin
Authors: Feil Sylvia
Published: December 2003

Dieses Jahr geht der Nobelpreis für Medizin an den Amerikaner Paul Lauterbur und den Briten Peter Mansfield. Beide entwickelten die Kernspinresonanz‐Spektroskopie zu einem bildgebenden Verfahren weiter.
Radial glia produce and align the ligand fibronectin during neuronal migration in the developing chick brain
Authors: Stettler Erin M. , Galileo Deni S.
Published: December 2003

We demonstrated previously that α8β1 integrin regulates the migration and survival of immature neurons during development of the chicken optic tectum; however, the potential extracellular ligand was unknown. We used immunohistochemistry to determine if several potential ligands (fibronectin, tenascin, vitronectin, and osteopontin) were expressed during neuronal migration along radial glia (RG). Fibronectin was localized in a pattern relevant to radial migration and survival of neurons; it was present before and during neuronal migration and appeared oriented along RG fibers by conventional fluorescence microscopy. Confocal microscopy confirmed that fibronectin was localized along RG cells during radial migration. It was more concentrated in some superficial laminae, which might support directional movement. Fibronectin was present after formation of definitive tectal laminae, but was diffuse and not aligned along RG, which persist. Flow cytometry analysis of dissociated optic tectum cells revealed that almost all RG were positive for fibronectin. Short‐term cell culture experiments using an exocytosis inhibitor revealed that fibronectin accumulated in most RG cells. Thus, fibronectin is produced by RG and is aligned along their surfaces before and during migration. Fibronectin, therefore, is a potential ligand for general radial neuronal migration in the chick optic tectum. Its predominant source appears to be RG, in contrast with developing mammalian cortex, where fibronectin was not found in a pattern that could guide widespread radial migration and where neurons are the predominant producers of fibronectin during migration. J. Comp. Neurol. 468:441–451, 2004. © 2003 Wiley‐Liss, Inc.
Spectral spaces and color spaces
Authors: Ramanath Rajeev , Kuehni Rolf G. , Snyder Wesley E. , Hinks David
Published: December 2003

It has long been known that color experiences under controlled conditions may be ordered into a color space based on three primary attributes. It is also known that the color of an object depends on its spectral reflectance function, among other factors. Using dimensionality reduction techniques applied to reflectance measurements (in our case a published set of 1 nm interval reflectance functions of Munsell color chips) it is possible to construct 3D spaces of various kinds. In this article we compare color spaces, perceptual or based on dimensionality reduction using color matching functions and additional operations (uniform color space), to spectral spaces derived with a variety of dimensionality reduction techniques. Most spectral spaces put object spectra into the ordinal order of a psychological color space, but so do many random continuous functions. In terms of interval scales there are large differences between color and spectral spaces. In spectral spaces psychophysical metamers are located in different places. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 29–37, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10211
Color rendering: A calculation that estimates colorimetric shifts
Authors: Worthey James A.
Published: December 2003

Lights vary in their ability to render object spectral reflectances into color contrasts. When a light L1 is replaced by another L2, even if L2 matches L1 in chromaticity, systematic color shifts may occur, including a loss or gain of chromatic color. For instance, many familiar lights, when compared to daylight, dull red and green objects, rendering them closer to gray. An opponent colors method is appropriate to this discussion because it brings to the surface the notion of chromatic color, meaning actual departure from white or gray. In this article, an opponent‐colors analysis leads to a matrix formulation that serves two purposes. The effects of replacing L1 by L2 are estimated with a 3×3 “rendering matrix” P. Given an object's tristimulus vector under L1, the method makes an approximate prediction of the new tristimulus vector under L2. Thanks to the opponent formulation, matrix element P22 quantifies the gain or loss of redness and greenness, while P33 expresses gain or loss of blueness and yellowness. These in fact are major effects, so the method is both quantitative and explanatory. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 43–56, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10213
Effect of sodium chloride, sodium tripolyphosphate and pH on color properties of pork meat
Authors: Fernández‐López J. , Sayas‐Barberá E. , Pérez‐Alvarez J. A. , Aranda‐Catalá V.
Published: December 2003

The myoglobin state determines the color of meat, and most of the additives used in processing meat products cause color changes. The aim of this study was to quantify the effect of pH (4.0, 5.0 and 6.0), sodium chloride (0, 1.5 and 3.0%) and sodium tripolyphosphate (0, 0.15 and 0.30%) on the color properties and myoglobin states of pork meat (Subscapularis muscle). CIELAB color parameters (Lightness, redness, yellowness, chroma and hue) and reflectance spectrum, between 400–700 nm, were obtained. The different myoglobin forms (deoxymyoglobin, oxymyoglobin and metmyoglobin) were quantified using K/S reflectance values. Both, sodium chloride and tripolyphosphate reduced meat lightness, although the latter additive did not modify redness, yellowness, chroma or hue, but stabilized the percentage of oxymyoglobin. A decrease in pH and the addition of sodium chloride or sodium tripolyphosphate, led to an increase in the Metmyoglobin percentage. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 67–74, 2004; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/col.10215
Collision processes of Hydride species in Hydrogen plasmas: III. The Silane family
Authors: Janev R. K. , Reiter D.
Published: December 2003

Cross sections are provided for most important collision processes of the Silicon‐Hydrides from the “Silanefamily”: SiHy (y = 1 − 4) molecules and their ions SiH+y, with (plasma) electrons and protons. The processes include: electron impact ionization and dissociation of SiHy, dissociative excitation, ionization and recombination of SiH+y ions with electrons, and charge ‐ and atom ‐ exchange in proton collisions with SiHy. All important channels of dissociative processes are considered. Information is also provided on the energetics (reactants/products energy loss / gain) of each individual reaction channel. Total and partial cross sections are presented in compact analytic forms.

The critical assessment of data, derivation of new data and presentation of results follow closely the concepts of the recently published related databases for Carbon‐Hydrides, namely for the Methane family [1, 2], and for the Ethane‐ and the Propane families [3], respectively. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Use of average value of Langmuir probe characteristic for characterization of pulsed discharges
Authors: Blažek J. , Špatenka P. , Taeschner Ch. , Leonhard A.
Published: December 2003

Based on numerical calculations a new method has been developed, which enables plasma analysis from the average value of the Langmuir probe current measured in pulsed discharge. The application of this method for characterization of a planar reactor used for plasma enhanced chemical vapor deposition of TiN and (TiAl)N hard coatings is described as an example. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laser plasma plume kinetic spectroscopy of the nitrogen and carbon species
Authors: Zelinger Z. , Novotný M. , Bulíř J. , Lančok J. , Kubát P. , Jelínek M.
Published: December 2003

The formation and decay of carbon and nitrogen atoms, CN radicals and C2 molecules were monitored using spatial‐ and time‐resolved emission spectroscopy in a plasma plume formed during laser ablation of a graphite target in nitrogen atmosphere. A simple exponential model was used to explain the effect of the individual chemical reactions and plasma dynamics on the measured kinetic characteristics. The succession of emissions C → N → CN was observed in the time‐resolved spectra, supporting the suggestion that the CN radical is formed mainly by the direct reaction C + N → CN or C2 + N2 → 2CN. The formation of CN radical was enhanced by the additional generation of atomic nitrogen through the RF discharge. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Van der Waal's approach in the theory of phase transitions in complex plasmas
Authors: Tsytovich V. N. , Morfill G. E. , Ivlev A.V.
Published: December 2003

Van der Waal's approach is used to describe the equation of state of complex plasmas with dust‐dust interactions including: the screened Coulomb interaction, long range non‐collective repulsion, shadow non‐collective attraction and collective interactions. For both cases, where either the collective or non‐collective dust‐dust attraction is present, the critical values of the coupling parameter Γd,cr are found (Γd = Q2n1/3d /Td, Q is the dust charge, nd is the dust density and Td is the dust temperature). The critical values of Γ depend on effectiveness of the attraction and for non‐collective attraction depend also on the size of the system. In substantially large complex plasma systems where the transitions to the crystal and liquid states were observed the collective attraction is operating and for small sizes systems corresponding to the complex plasma clusters the non‐collective attraction is operating. The theoretical results obtained from Van der Waal's approach are compared with observations. It is shown that the phase transitions are not possible for a pure screened Coulomb (Yukawa) interactions. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stimulated Brillouin backscattering in magnetized plasmas
Authors: Bawa'aneh M. S.
Published: December 2003

Stimulated Brillouin backscattering (SBBS) from a magnetized homogeneous plasma is investigated. Effect of a dc–magnetic field on SBBS growth rate is obtained and compared with that for non–magnetized plasmas. Numerical calculations show an increase in the instability growth rate for small magnetic fields, then a decrease in the growth rate as the magnetic field increases till a cut–off field is reached, beyond which SBBS is brought to stability. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An optical probe for local ion temperature measurements in a plasma
Authors: Kiss'ovski Zh. , Bohmeyer W. , Fussmann G.
Published: December 2003

Local measurements of the ion temperature and the spectral emissivity have been performed in the magnetized plasma of the PSI‐2 device using an optical probe. The proper operation of the probe could be demonstrated. The probe collects the light emission from a small separated plasma volume thus enabling to determine the ion temperature from Doppler‐broadening of suited spectral lines. In addition to the technical features stray light and finite Larmor radii effects ‐ limiting the spatial resolution ‐ are discussed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural Studies on Hydrogen‐Bonding Receptors for Barbiturate Guests That Use Metal Ions as Allosteric Inhibitors
Authors: Al‐Sayah Mohammad H. , McDonald Robert , Branda Neil R.
Published: December 2003

Receptor 1 was designed to bind barbiturate substrates through a six‐point hydrogen‐bonding motif only in the absence of metal allosteric cofactors. It was predicted that the binding of metal ions by bipyridine ligands in 1 would result in a geometric change in the receptor to inhibit substrate recognition. However, receptor 1 showed minimal affinity for the barbiturate guests even in the absence of the metal. Binding studies on model compounds 2, 3, 5, and 6 revealed that the inactivity of 1 is due to an intramolecular hydrogen bond between the N−H donor groups and the nitrogen atoms on the first heterocycle of the bipyridine ligands. This intramolecular hydrogen‐bonding was eliminated by altering the position of the tether between the bipyridine ligands and the active site to produce receptor 7. Consequently, the high affinity exhibited by 7 for the barbiturate substrate (Ka = 2.8±0.7 × 103 M−1 in 9:1 CD2Cl2/CD3CN) was significantly reduced by the addition of ZnII ions as a negative allosteric co‐factor. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Quaternary Ammonium‐Supported Scavenger Reagents for Acids and Electrophiles
Authors: Ghanem Noha , Martinez Jean , Stien Didier
Published: December 2003

The present article describes how we devised new quaternary ammonium‐supported quench reagents (TAMA‐Cl and BAX‐sulfate) for scavenging acids and excess electrophiles from crude reaction mixtures. TAMA‐Cl is liquid at room temperature, but is very glutinous and has to be used in aqueous solution. It removes unchanged electrophiles very efficiently. An aqueous preparation of TAMA‐Cl may be easily added in automated syntheses, and high‐throughput phase‐separation techniques should allow purification of scavenger‐containing reaction mixtures. However, workup with TAMA‐Cl is more complex than simple filtration. Recognizing this major advantage of solid‐phase syntheses, we designed BAX‐sulfate, a highly crystalline scavenger reagent that allows reaction workup to be simplified to a single filtration and evaporation of solvent. BAX‐sulfate reacts with electrophiles, quenches acids and precipitates quantitatively when diethyl ether is added. It even precipitates from methanol solutions. With BAX‐sulfate the workup stage uses simple filtration to make crude separations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Phthalocyaninatoindium(III) Acetylacetonates for Nonlinear Optics
Authors: Youssef Tamer Ezzat , O’Flaherty Sean , Blau Werner , Hanack Michael
Published: December 2003

The monomeric octaethylhexyl‐ and tetra‐tert‐butyl‐substituted phthalocyanines 3 and 12 with axial acetylacetonate as ligands were synthesized and characterized, in order to compare their optical limiting properties with the state‐of‐the‐art molecule [tetra‐(tert‐butyl)phthalocyaninato]indium chloride (tBu)4PcInCl (1a) and the phthalocyanines 1b−f. In addition, the trimer 17 was also synthesized (as a mixture of isomers). The synthesis of 3, 12 and 17 was carried out by refluxing the corresponding metal‐free phthalocyanines, (tBu)4PcH2 (2), (RO)8PcH2 (6) (R = 2‐ethylhexyl) and the trimer 16 with an excess of In(acac)3 in DMF. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthetic Studies on Pandanus Alkaloids: From Norpandamarilactonines to Pandamarilactonines, a Proof of Their Configurational Instability
Authors: Blanco Pilar , Busqué Felix , de March Pedro , Figueredo Marta , Font Josep , Sanfeliu Elena
Published: December 2003

The ethyl carbamate of norpandamarilactonine‐A was prepared in an enantiomerically pure form starting from (S)‐prolinol. Deprotection of the amine functionality rendered both diastereomeric norpandamarilactonines as racemates, which were used as synthetic precursors of pandamarilactonine‐A and ‐B. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
An Investigation on the Synthesis of New Molecular Architectures from the Cyclotrimerisation of exo‐ and endo‐Benzotricyclo[4.2.1.02,5]nonene
Authors: Dastan Arif , Uzundumlu Eren , Balci Metin , Fabris Fabrizio , Lucchi Ottorino De
Published: December 2003

We have performed an investigation on the cyclotrimerisation of molecules having exo‐ and endo‐benzotricyclo[4.2.1.02,5]nonene skeletons (3 and 4) with the aim of producing their respective cyclotrimers 2 that feature unusual geometries and electronic properties. Activation towards the cyclotrimerisation reaction was performed using the vic‐bromostannyl vinyl derivatives and was accomplished under copper‐mediated or palladium‐catalysed reaction conditions. While the exo isomer 3 proved to be quite reactive and afforded variable amounts of the syn and anti cyclotrimers, the endo isomer 4 turned out to be quite resistant to cyclotrimerisation because of steric hindrance. Only dimers and acyclic trimers were obtained from reactions using this substrate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Structural Homology and Dynamic Variation in a Series of Porphyrin Bipyridinium Receptors and Their [2]Catenanes
Authors: Gunter Maxwell J. , Jeynes Tyrone P. , Turner Peter
Published: December 2003

We describe the successful synthesis of the porphyrin [2]catenanes, which completes a set of six structures where the length of the polyethylene glycol strap over the porphyrin is regularly increased from diethylene to triethylene to tetraethylene, and the central electron‐donor component is either hydroquinol‐ or naphthoquinol‐based. In the synthetic route to the strapped porphyrin precursors, co‐formation of “straight” and “twisted” atropisomers in the longer strapped derivatives, and dimeric and higher oligomeric structures for the shorter straps, has been observed. Catenation results in only a single [2]catenane in each case. X‐ray crystal structures of two representative strapped porphyrins are described. For each of the untwisted singly‐strapped porphyrins, there is significant binding of paraquat within the cavity formed by the strap, and the binding constants range over about two orders of magnitude. For the catenanes, in each case the overall structural motif is similar to that previously observed for related members of the series. The temperature‐dependent dynamic properties of the catenanes have been examined by 1H NMR methods, and the rates of rotation increase from 50 to 25 000 to 340 000 s−1 at room temperature as the length of the strap increases by one ethylene glycol unit on each side. For the similarly sized naphthoquinol derivatives, the rotation rates are reduced by many orders of magnitude, ranging from essentially zero to 10 to 100 times per second at 25 °C through the same increase in chain length as for the hydroquinol analogues. The rates for a second process described as “out, turn around and in again”, range from 2 to 400 to 110 000 s−1 at 25 °C in this naphthoquinol porphyrin series. The electronic spectra of the catenanes themselves do not show any significantly enhanced charge‐transfer bands over the hydroquinol counterparts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Deprotonation‐Triggered Heavy‐Halogen Migrations as a Key to the Structural Elaboration of 2,2‐Difluoro‐1,3‐benzodioxole
Authors: Gorecka Joanna , Leroux Frédéric , Schlosser Manfred
Published: December 2003

Although proton abstraction from the 4‐position of 2,2‐difluoro‐1,3‐benzodioxole occurs with exceptional ease, lithiation of the more‐remote 5‐position can only be brought about if no oxygen‐adjacent site remains unoccupied. Thus, unlike 4‐bromo‐2,2‐difluoro‐1,3‐benzodioxole (1), (7‐bromo‐2,2‐difluoro‐1,3‐benzodioxol‐4‐yl)triethylsilane (5b) does react with lithium diisopropylamide to generate an intermediate that isomerizes instantaneously by heavy‐halogen migration. Upon neutralization and carboxylation, 5‐bromo‐2,2‐difluoro‐1,3‐benzodioxole (8) and 5‐bromo‐2,2‐difluoro‐1,3‐benzodioxole‐4‐carboxylic acid (3) are formed nearly quantitatively. A similar basicity gradient‐driven heavy‐halogen migration can be accomplished starting from 2,2‐difluoro‐4,7‐diiodo‐1,3‐benzodioxole (11). These results procure a deeper insight in the acidifying effects of fluoroalkoxy groups and their distance dependence. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Copolymerized polymeric surfactants: Characterization and application in micellar electrokinetic chromatography
Authors: Akbay Cevdet , Gill Nicole L. , Agbaria Rezik A. , Warner Isiah M.
Published: December 2003

An achiral monomeric surfactant (sodium 10‐undecenyl sulfate, SUS) and a chiral surfactant (sodium 10‐undecenoyl L‐leucinate, SUL) were synthesized and polymerized individually to form poly‐SUS and poly‐SUL. These surfactants were then copolymerized at various molar ratios to produce a variety of copolymerized surfactants (CoPSs), possessing both achiral (sulfate) and chiral (leucinate) head groups. The CoPSs, poly‐SUS, poly‐SUL, and sodium dodecyl sulfate were characterized using several analytical techniques. The aggregation numbers of the polymeric surfactants and the partial specific volumes were determined by the use of fluorescence quenching and density measurements, respectively. These polymeric surfactants were investigated as novel pseudostationary phases in micellar electrokinetic chromatography (MEKC) for the separation of chiral and achiral solutes. Solute hydrophobicity was found to have major influence on the MEKC retention of alkyl phenyl ketones. In contrast, hydrogen‐bonding ability of benzodiazepines is the major factor that governs their retention, but hydrophobicity has an insignificant effect on MEKC retention of benzodiazepines.
Characterization of antithrombin III from human plasma by two‐dimensional gel electrophoresis and capillary electrophoretic methods
Authors: Kremser Leopold , Brückner Andrea , Heger Andrea , Grunert Tom , Buchacher Andrea , Josic Djuro , Allmaier Günter , Rizzi Andreas
Published: December 2003

The isoforms distribution of the glycoprotein antithrombin III (ATIII) derived from human plasma was investigated by means of isoelectric focusing (IEF) in polyacrylamide gels with immobilized pH gradients (IPG) and two‐dimensional gel electrophoresis (2‐DE) as well as capillary electrophoretic methods. It turned out that the presence of high concentrations of chaotropics (urea, thiourea) and zwitterionic detergents (3‐[(3‐cholamidepropyl)dimethylammonio]‐1‐propanesulfonate (CHAPS)) was decisive for attaining good resolution of the protein isoforms. Resolution by IPG‐IEF was obtained with excellent reproducibility and pI differences down to 0.01 pH units could be distinguished. ATIII‐α and ATIII‐β‐fractions preseparated by heparin affinity chromatography showed an analogous but shifted spot pattern consisting each of one major and three minor isoforms. The main isoforms of ATIII‐α and ATIII‐β exhibit pI values of 5.18 and 5.32, respectively, both values determined in the presence of high concentrations of urea. The pI difference of 0.14 pH units correspond to the effect of two sialic acids absent in ATIII‐β. The formation and occurrence of ATIII dimers and trimers turned out to be dependent on the sample preparation. The results obtained by 2‐DE were compared with those of capillary zone electrophoresis (CZE) and capillary IEF (CIEF). Quantitative analysis regarding the CZE separated isoforms of plasma derived ATIII yielded a content of about 70% ATIII‐α main isoform and about 6.6% of ATIII‐β. The pI values of ATIII determined by CIEF with internal calibration were in fair agreement with the pI values of the main isoforms achieved with 2‐DE.
Characterization of surfactant and phospholipid vesicles for use as pseudostationary phases in electrokinetic chromatography
Authors: Pascoe Robert J. , Foley Joe P.
Published: December 2003

The physical, electrophoretic and chromatographic properties (mean diameter, electroosmotic flow, electrophoretic mobility, elution range, efficiency, retention, and hydrophobic, shape, and chemical selectivity) of three surfactant vesicles and one phospholipid vesicle were investigated and compared to a conventional micellar pseudostationary phase comprised of sodium dodecyl sulfate (SDS). Chemical selectivity (solute‐pseudostationary phase interactions) was discussed from the perspective of linear solvation energy relationship (LSER) analysis. Two of the surfactant vesicles were formulated from nonstoichiometric aqueous mixtures of oppositely charged, single‐tailed surfactants, either cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) in a 3:7 mole ratio or octyltrimethylammonium bromide (OTAB) and SDS in a 7:3 mole ratio. The remaining surfactant vesicle was comprised solely of bis(2‐ethylhexyl)sodium sulfosuccinate (AOT) in 10% v/v methanol, and the phospholipid vesicle consisted of 1‐palmitoyl‐2‐oleyl‐sn‐glycero‐3‐phosphocholine (POPC) and phosphatidyl serine (PS) in 8:2 mole ratio. The mean diameters of the vesicles were 76.3 nm (AOT), 86.9 nm (CTAB/SOS), 90.1 nm (OTAB/SDS), and 108 nm (POPC/PS). Whereas the coefficient of electroosmotic flow (10−4 cm2 V−1 s−1) varied considerably (1.72 (OTAB/SDS), 3.77 (CTAB/SOS), 4.05 (AOT), 5.26 (POPC/PS), 5.31 (SDS)), the electrophoretic mobility was fairly consistent (−3.33 to −3.87×10−4 cm2 V−1 s−1), except for the OTAB/SDS vesicles (−1.68). This resulted in elution ranges that were slightly to significantly larger than that observed for SDS (3.12): 3.85 (POPC/PS), 8.6 (CTAB/SOS), 10.1 (AOT), 15.2 (OTAB/SDS). Significant differences were also noted in the efficiency (using propiophenone) and hydrophobic selectivity; the plate counts were lower with the OTAB/SDS and POPC/PS vesicles than the other pseudostationary phases (≤ 75 000/m vs. > 105 000/m), and the methylene selectivity was considerably higher with the CTAB/SOS and OTAB/SDS vesicles compared to the others (ca. 3.10 vs. ≤ 2.6). In terms of shape selectivity, only the CTAB/SOS vesicles were able to separate all three positional isomers of nitrotoluene with near‐baseline resolution. Finally, through LSER analysis, it was determined that the cohesiveness and hydrogen bond acidity of these pseudostationary phases have the greatest effect on solute retention and selectivity.
Nonaqueous capillary electrophoretic separation of polyphenolic compounds in wine using coated capillaries at high pH in methanol
Authors: Demianová Zuzana , Sirén Heli , Kuldvee Ruth , Riekkola Marja‐Liisa
Published: December 2003

Nonaqueous capillary electrophoretic separation of a group of flavonoids (quercetin, myricetin, catechin, epicatechin) and resveratrol in wine was investigated in methanol at high pH. Malonate background electrolyte (pH* 13.5, ionic strength I = 14.2 mmol/L) provided highly repeatable separations of the analytes. Tests of untreated and coated (poly(glycidylmethacrylate‐co‐N‐vinylpyrrolidone)) capillaries showed the analysis to be faster (6.5 min vs. 25 min) and the repeatability better in the coated capillaries. The coating procedure was simple and highly repeatable and the coating was stable during 40–45 runs. Determination of the last migrating peaks (epicatechin, resveratrol and catechin) was achieved merely by evaporating the wine samples and reconstituting the residue in methanol. For determination of the first migrating peaks (quercetin and myricetin) the samples were submitted to solid‐phase extraction in C8 cartridges.
Proteomic analysis of pancreatic ductal carcinoma cells treated with 5‐aza‐2'‐deoxycytidine
Authors: Cecconi Daniela , Astner Hubert , Donadelli Massimo , Palmieri Marta , Missiaglia Edoardo , Hamdan Mahmoud , Scarpa Aldo , Righetti Pier Giorgio
Published: December 2003

A pancreatic adenocarcinoma cell line (PaCa44), which contains, among other alterations, a methylated p16 promoter, was treated with a chemoterapeutic agent, 5‐aza‐2'‐deoxycytidine (DAC), in order to evaluate the effect of this drug on cell growth and protein expression. Cell proliferation was strongly inhibited by a 24 h DAC treatment and this inhibition lasted for at least 10 days. Master maps of control and treated PaCa44 cells were generated by analysis with the PDQuest software. The comparison between such maps showed up‐ and downregulation of 45 polypeptide chains, of which 32 were downregulated and 13 upregulated, out of a total of 700 spots detected by a medium‐sensitivity stain, micellar Coomassie Brilliant Blue. Fingerprinting by mass spectrometry analysis enabled the identification of 36 of these spots. Among the major changes in DAC‐treated cells: cofilin and profilin 1 are silenced; coactosin, peptidyl‐propyl cis‐trans isomerase A and cystatin B are decreased by 22, 16‐ and 15‐fold, respectively; stress‐70 protein, superoxide dismutase and protein disulfide isomerase A3 are increased by 13‐, 11‐, and 5‐fold, respectively. The significance of some of these major changes is discussed.
Incorporating appreciative inquiry methods to evaluate a youth development program
Authors: Hanson Smart Dawn , Mann Mariann
Published: December 2003

This chapter presents a case study that used Appreciative Inquiry techniques in conjunction with conventional evaluation methods. It discusses the benefits of using Appreciative Inquiry methods and issues the evaluators encountered.
Editors' notes
Authors: Preskill Hallie , Coghlan Anne T.
Published: December 2003

Editor's notes
Appreciative evaluation within a conflicted educational context
Authors: McNamee Sheila
Published: December 2003

The case in this chapter illustrates how using the language of strengths, values, and ideals can help participants take stock of their program in order to move forward what they most value in the process of curricular reform and collaborative working relations.
Using appreciative inquiry to guide an evaluation of the International Women's Media Foundation Africa program
Authors: Tzavaras Catsambas Tessie , Webb Laverne D.
Published: December 2003

This chapter describes how Appreciative Inquiry methods were used to focus the evaluation of an international nonprofit organization's Africa‐based center, develop interview guides and a questionnaire, engender trust, and maximize utilization of results.