bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractN‐(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

AbstractTreatment 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

AbstractUDP‐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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractEight 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

AbstractTreatment 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.
Naturfarbstoffe: Farben mit Geschichte
Authors: Struckmeier Sabine 
Published: December 2003

AbstractBis 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

AbstractIn 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

AbstractWenn 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

AbstractDieses 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

AbstractWe 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

AbstractIt 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

AbstractLights 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

AbstractThe 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

AbstractCross 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

AbstractBased 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

AbstractThe 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

AbstractVan 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

AbstractStimulated 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)