bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computer simulations in solid‐state NMR. II. Implementations for static and rotating samples
Authors: Edén Mattias 
Published: April 2003

AbstractIn the first article in this series (Concepts Magn Reson Part A 17A:117–154, 2003), we outlined a theoretical framework for calculating solid‐state NMR time‐domain signals and frequency‐domain spectra. This article explains how the theory may be implemented on a computer for simulating NMR signals from a single crystal in a static and rotating sample. The general building blocks of a computer program for numerically calculating NMR signals are discussed. Computer algorithms for carrying out the simulations are presented as flowcharts and implemented in C/C++ code. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part A 18A: 1–23, 2003
Idiotype‐specific CD4+CD25+ T suppressor cells prevent, by limiting antibody diversity, the occurrence of anti‐dextran antibodies crossreacting with histone H3
Authors: Specht Christoph , Schlüter Bernhard , Rolfing Meike , Brüning Kristina , Pauels Hans‐Gerd , Kölsch Eckehart 
Published: April 2003

AbstractCD25+ suppressor T cells regulate the immune response against the type‐2 "thymus independent" bacterial polysaccharide antigen α(1→3)dextran (Dex) in BALB/c mice. These T cells, represented by the clone 178‐4 Ts, restrict the Dex‐specific IgG antibody repertoire such that the J558 idiotype dominates. Antibodies with other structures in the heavy‐chain variable region (VH region), predominantly within the CDR3 domain, occur when the T cell control fails. This increase of antibody diversity caused by a lack of CD25+ Ts cells, e.g. in nude mice, does not result in the appearance of antibodies with enhanced affinity to the antigen Dex, but often leads to a crossreactivity with autologous proteins. Twenty‐two out of sixty Dex‐specific hybridomas from nude mice, but no hybridomas from euthymic mice, crossreact with a nuclear protein, as tested by ELISA. This nuclear protein was identified as histone H3. Ten of the sixty hybridomas from nude mice were sequenced and show VH sequences that deviate from the original J558 sequence. Three of these ten hybridomas crossreact with the histone H3. Adoptive transfer of CD25+ Ts cells to nude mice leads to a marked increase of antibodies carrying the original J558 idiotype within the IgG pool after immunization with Dex. Our data demonstrate a CD25+ Ts cell‐mediated restriction of VH usage, which prevents the appearance of crossreactive autoantibodies.
Pax‐5 is a key regulator of the B cell‐restricted expression of the CD23a isoform
Authors: Visan Ioana , Goller Martin , Berberich Ingolf , Kneitz Christian , Tony Hans‐Peter 
Published: April 2003

AbstractHuman CD23 (the low affinity IgE receptor) is a B cell differentiation marker involved in inflammatory responses. Two isoforms (CD23a and CD23b) are known, which differ only in their cytoplasmic domain. Whereas CD23b expression is specifically induced by IL‐4 on B cells and cells of the myeloid lineage, CD23a expression is restricted to B cells. Each isoform is regulated by its own promoter. Pax‐5 is a B‐cell‐restricted transcription factor with an essential role in early and late B cell development. Analyses of the CD23a promoter revealed a Pax‐5‐binding site, which can compete a high affinity Pax‐5‐binding site or directly bind Pax‐5 protein in electrophoretic mobility shift assays. Introducing mutations into this site abrogates the binding. Expression of Pax‐5 in 293 cellsresulted in a seven‐ to tenfold activation of a CD23a core promoter construct. Most importantly, ectopic expression of Pax‐5 in the monocytic cell line U‐937, which regularly expresses only the CD23b isoform, led to CD23a expression after stimulation with IL‐4 and PMA. Our results suggest that Pax‐5 is a key regulator of the B‐cell‐restricted expression of the CD23a isoform.
Redundant functions of TCF‐1 and LEF‐1 during T and NK cell development, but unique role of TCF‐1 for Ly49 NK cell receptor acquisition
Authors: Held Werner , Clevers Hans , Grosschedl Rudolf 
Published: April 2003

AbstractMembers of the TCF/LEF (T cell factor / lymphoid enhancer factor) family of DNA‐binding factors play important roles during embryogenesis, the establishment and/or maintenance of self‐renewingtissues such as the immune system and for malignant transformation. Specifically, it has been shown that TCF‐1 is required for T cell development. A role for LEF‐1 became apparent when mice harbored two hypomorphic TCF‐1 alleles and consequently expressed low levels of TCF‐1. Here we show that NK cell development is similarly regulated by redundant functions of TCF‐1 and LEF‐1, whereby TCF‐1 contributes significantly more to NK cell development than LEF‐1. Despite this role for NK cell development, LEF‐1 is not required for the establishment of a repertoire of MHC class I‐specific Ly49 receptors on NK cells. The proper formation of this repertoire depends to a large extent on TCF‐1. These findings suggest common and distinct functions of TCF‐1 and LEF‐1 during lymphocyte development.
Inactivation of the EGF‐TM7 receptor EMR4 after the Pan‐Homo divergence
Authors: Hamann Jörg , Kwakkenbos Mark J. , de Jong Esther C. , Heus Henk , Olsen Anne S. , van Lier René A.W. 
Published: April 2003

AbstractWe here report on the identification of a novel human EGF‐TM7 receptor, designated EMR4. Like most EGF‐TM7 receptor genes, EMR4 is localized on the short arm of chromosome 19, in close proximity to EMR1. Remarkably, due to a one‐nucleotide deletion in exon 8, translation of human EMR4 would result in a truncated 232‐amino acid protein lacking the entire seven‐span transmembrane region. This deletion is not present in nonhuman primates, including chimpanzees, suggesting that EMR4 became nonfunctional only after human speciation, about five million years ago. Thus, EMR4 surprisingly accounts for a genetic difference between humans and primates related to immunity.
Heterotrinuclear Complexes of the Platinum Group Metals with 2,2′‐Biimidazole as a Bridging Ligand
Authors: Mayboroda Andrey , Comba Peter , Pritzkow Hans , Rheinwald Gerd , Lang Heinrich , Koten Gerard van 
Published: April 2003

AbstractThe novel trinuclear complexes [(Pt{C6H3(CH2NMe22,6)2})2(μ‐Hbiim)2Os(O=PPh3)2](NO3)(SO3CF3)2 [C6H3(CH2NMe2‐2,6)2 = pincer ligand, H2biim = 2,2′‐biimidazole] and [(PdL)2(μ‐biim)2Os(O=PPh3)2](NO3)3 (L = cod, 1,5‐cyclooctadiene or L = en, ethylene‐1,2‐diamine) were prepared by the reaction of the mononuclear complex [Os(H2biim)2(O=PPh3)2](NO3)3 with [Pt{C6H3(CH2NMe2‐2,6)2}](SO3CF3), or with PdL(NO3)2 (L = cod or L = en), in the presence of a base. The exchange reaction between [Os(Hbiim)2(O=PPh3)2](NO3)3 and [Me2NH2][RhCl4(NHMe2)] led to the formation of [Os(Hbiim)2(O=PPh3)2][RhCl4(NHMe2)]. The solid‐state structures of [Os(Hbiim)2(O=PPh3)2][RhCl4(NHMe2)] and [(Pt{C6H3(CH2NMe2‐2,6)2})2(μ‐Hbiim)2Os(O=PPh3)2](NO3)(SO3CF3)2·4H2O were determined by single‐crystal X‐ray diffraction. The crystals of [Os(Hbiim)2(O=PPh3)2][RhCl4(NHMe2)] are triclinic with a space group P$\bar 1$
, with a = 10.4293(5), b = 10.6365(6), c = 13.0287(7) Å, β = 91.6840(10), γ = 109.8540(10)°, V = 1316.14(12) Å3, Z = 1. The crystals of the complex [(Pt{C6H3(CH2NMe2‐2,6)2})2(μHbiim)2Os(O=PPh3)2](NO3)(SO3CF3)2·4H2O are triclinic with a space group P$\bar 1$
, with a = 12.604(3), b = 13.471(3), c = 14.347(3) Å, β =77.530(5), γ = 66.613(4)°, V = 2005.6(7) Å3, Z = 1. Deprotonation of 2,2′‐biimidazole in the mononuclear osmium complex, followed by coordination to an additional transition metal fragment leads to a modification of the ligand field and a variation of the redox properties of the OsIII center. [{Pd(cod)}2(μ‐biim)2Os(O=PPh3)2](NO3)3 shows significant catalytic activity towards hydrogenation of terminal and cyclic alkenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structural Characterization and a New One‐Pot Synthesis of trans‐Chloro(phenyl)bis(triphenylphosphane)nickel(II)
Authors: Zeller Alexander , Herdtweck Eberhardt , Strassner Thomas 
Published: April 2003

Abstracttrans‐[NiCl(Ph)(PPh3)2], the organometallic precursor for a new class of neutral polymerization catalysts, has been synthesized via a new synthetic route. The previously used alkylaluminum compounds are replaced by zinc dust for the reduction of the nickel(II) salt in the presence of triphenylphosphane forming the intermediate Ni(PPh3)4. In a one‐pot reaction, chlorobenzene then adds oxidatively to the intermediate to form the title compound, which was structurally characterized, in high yields. Its geometry is compared to known structures of the higher homologues of group 10. All complexes adopt a distorted square‐planar geometry, but the parent structure shows significantly shorter metal‐ligand bond lengths than its Pd and Pt congeners, as expected. Density functional theory calculations (B3LYP/6−31G*) on the full structure are in very good agreement with the solid‐state structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Solvothermal Synthesis of a Layered Open‐Framework Chlorocadmium Oxalate, Cd2(C2O4)0.5Cl3NaCl·4H2O
Authors: Vaidhyanathan R. , Natarajan Srinivasan , Rao C. N. R. 
Published: April 2003

AbstractThe metathesis reaction between CdCl2·2H2O and sodium oxalate in n‐hexanol under solvothermal conditions yields a hybrid compound of formula Cd2(C2O4)0.5Cl3NaCl·4H2O. It consists of one‐dimensional chains formed by Cd and Cl atoms, containing μ2(Cl) and μ3(Cl) bridges, and cross‐linked by oxalate units to give a layered structure. The Na+ ions and water molecules occupy the interlamellar spaces. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Rapid and Selective Oxidation of Metallosulfophthalocyanines Prior to Their Usefulness as Precatalysts in Oxidation Reactions
Authors: d’Alessandro Nicola , Tonucci Lucia , Bressan Mario , Dragani Luana K. , Morvillo Antonino 
Published: April 2003

AbstractTwo metallosulfophthalocyanines, RuPcS and FePcS, used in many catalytic oxidation reactions, were readily oxidized by hydrogen peroxide or monopersulfate, under acidic or neutral conditions in water, to form novel metal complexes derived from the facile oxidation of the PcS ring. Meso‐nitrogen‐oxide derivatives and metal‐biliverdin‐like derivatives were identified among the products at early reaction times, whereas at longer times fragmentation of the phthalocyanine ring occurred, with formation of sulfophthalimide and metal complexes containing the resulting tridentate ligand. The oxidative degradation of the MPcS complexes has been investigated by ESI‐MS, UV/Vis‐NIR and 1H, 13C and 15N NMR spectroscopy. These rapidly formed, coordinatively unsaturated complexes represent the dominant species in oxidizing media, at least in the case of the Ru derivative, and must be the real catalyst precursors in previously published oxidation reactions using MPcS complexes. The oxidative degradation reactions occurred with selective mono‐denitrogenation of one meso‐nitrogen atom and formation of ammonia, thus recalling the celebrated selective degradation of heme to verdoheme and/or biliverdin and CO. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Dicopper(II) Complex of the Novel Asymmetric Dinucleating Ligand Hpy3asym as a Structural Model of Catechol Oxidase
Authors: Koval Iryna A. , Pursche Daniel , Stassen Arno F. , Gamez Patrick , Krebs Bernt , Reedijk Jan 
Published: April 2003

AbstractThe new asymmetric dinucleating ligand 2‐{[bis(2‐pyridinylmethyl)amino]methyl}‐4‐methyl‐6‐{[(2‐pyridinylmethyl)amino]methyl}phenol (Hpy3asym) has been designed in order to model the type‐3 active site of the copper proteins. This phenol‐based “end‐off” compartmental ligand has one tridentate and one didentate arm attached to the 2‐ and 6‐positions of the phenolic ring, respectively. A dinuclear copper(II) nitrate complex with this ligand [Cu2(py3asym)(H2O)1.5(NO3)2]NO3 has been obtained and structurally characterized. In this complex both copper ions have a distorted octahedral geometry and are endogenously bridged by the phenolic oxygen atom of the deprotonated ligand. The complex shows a donor‐atom asymmetry that consists of an N3O3 donor set for the Cu1 ion and an N2O4 donor set for the Cu2 ion. The electrochemical, magnetic behavior and spectral properties of the complex are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Phosphane‐Substituted Selenido−(carbonyl)iron and −(carbonyl)ruthenium Clusters: Structures, Fluxionality and Reactivity
Authors: Graiff Claudia , Predieri Giovanni , Tiripicchio Antonio 
Published: April 2003

AbstractSelenium‐transfer reactions from tertiary phosphane and diphosphane selenides to the carbonyl clusters [M3(CO)12] (M = Fe or Ru) provide a simple, stepwise synthetic route to phosphane‐substituted, mono‐ and diselenido−(carbonyl)iron and −(carbonyl)ruthenium clusters. Four families of clusters are generally obtained: (i) the M2Se2L6 tetrahedral species (only for iron), (ii) the M3SeL10 capped triangular species, (iii) the M3Se2L9 square‐pyramidal nido species (for iron and ruthenium), and (iv) the M4Se2L11 octahedral closo species (only for ruthenium), with L being a phosphane or carbonyl ligand. When the tertiary phosphane selenide contains heterocyclic fragments, the reaction is not only limited to the transfer of the selenium atom, but proceeds by P−C and, sometimes, C−H bond cleavages, affording new selenido‐phosphido carbonyl clusters bearing coordinated heterocyclic fragments. Many clusters show fluxional behaviour in solution because of either ligand mobility or M−M bond migration. Furthermore, dimetallic substituted carbonyl clusters have been prepared by two different synthetic approaches: (1) MM′ + PSe (reactions between preformed dimetallic clusters and tertiary phosphane selenides) and (2) MSeP + M′ [cluster growth reactions from preformed chalcogenido− (carbonyl)metal clusters and suitable organometallic fragments]. In particular, from the tetrahedral clusters [HMCo3(CO)12] (M = Fe or Ru) monoselenido clusters [MCo2(μ3‐Se)] with a tetrahedral core have been obtained. The second type of approach has been applied to the open‐triangular nido clusters [Ru3(μ3‐Se)2(CO)9−nLn] (L = tertiary phosphane, n = 1 or 2), which can add zero‐s.e.p.’s organometallic fragments, such as M(CO)3 (M = Mo or W), giving the corresponding closo clusters [MRu3(µ4‐Se)2(CO)12−nLn]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Potentiometric Ion Sensors Based on Conducting Polymers
Authors: Bobacka Johan , Ivaska Ari , Lewenstam Andrzej 
Published: April 2003

AbstractConducting polymers (electroactive conjugated polymers, ECPs) have emerged as one of the most promising transducers for chemical sensors. This is related to the unique electrical, electrochemical and optical properties of conjugated polymers that can be used to convert chemical information (concentration, activity, partial pressure) into electrical or optical signals in the solid state. Application of conjugated polymers in potentiometric ion sensors (ion‐selective electrodes, ISEs) is reviewed.
Electrochemical and Microgravimetric Investigations of Lead, Cadmium and Copper Deposition and Stripping on Solid Electrodes
Authors: Wagner K. , Strojek J. W. , Koziel K. 
Published: April 2003

AbstractElectroanalytical methods and quartz crystal microbalance were used to study the mechanisms of deposition and stripping of lead in the presence of cadmium or copper at solid electrodes. Interaction between atoms of different metals deposited on the electrode surface change the heights and potentials of the stripping peaks and cause major errors in metal determination. The formation of a solid solution during simultaneous electroreduction of Pb and Cu was confirmed. ASV determination of lead in the presence of cadmium also gives uncertain results because cadmium atoms are covered (blocked) by lead and can be oxidized together with lead at more positive potential.
Application of Sol‐Gel Technology for Electroanalytical Sensing
Authors: Shustak G. , Marx S. , Turyan I. , Mandler D. 
Published: April 2003

AbstractThe applicability of thin sol‐gel films as selective interfaces in electrochemical sensors has been examined. This requires not only to create a selective interface but also to enable facile diffusion of the analytes across the films. Creation of selectivity has been aimed by molecularly imprinting an electroactive species in the course of sol‐gel formation. We have focused primarily on imprinting an iron(II) complex, i.e., tris(2,2′‐bipyridine)iron(II) (Fe(bpy)$\rm{ {_{3}^{2+}}}$$)$, as a means of selectively determining iron(II) in aqueous solution. Hence, the effect of different parameters, such as the composition of the sol‐gel film and the hydrolysis and drying time, on the diffusion of Fe(bpy)$\rm{ {_{3}^{2+}}}$, has been studied. We find that diffusion can be remarkably enhanced upon adding polyethylene glycol or a surfactant, such as decanoic acid. Nevertheless, so far we have not been able to develop thin films, which exhibit selectivity towards this inorganic species. The difficulties in designing such selective interfaces for heavy metals as opposed to organic species is demonstrated by successfully applying the same approach for designing a selective interface for diethyl‐p‐nitrophenyl phosphate (paraoxon).
Effect of the Volume Phase Transition on Diffusion and Concentration of Molecular Species in Temperature‐Responsive Gels: Electroanalytical Studies
Authors: Zhang Weimin , Gaberman Irina , Ciszkowska Malgorzata 
Published: April 2003

AbstractEffect of the volume phase transition on the diffusion and concentration of molecular probes was studied in temperature‐responsive polymeric hydrogels. Results were compared for two gels, poly(N‐isopropylacrylamide), NIPA, and poly(N‐isopropylacrylamide‐co‐acrylic acid), NIPA‐AA. These gels undergo discontinuous, reversible volume phase transition as a response to temperature changes; this transition results in release of approximately 40% and 90% of the solution/solvent from NIPA‐AA and NIPA gel phases, respectively. 1,1′‐Ferrocenedimethanol, Fc(MeOH)2, served as an electroactive and spectroscopic probe. Diffusion of Fc(MeOH)2 was investigated using voltammetry and chronoamperometry with platinum disk electrodes, while UV‐vis supported electroanalytical techniques to determine the concentration of that probe in the gel. The diffusion coefficient of Fc(MeOH)2 was inversely proportional to the concentration of the polymer in both NIPA and NIPA‐AA swollen gels for temperatures below the volume phase transition, and differed from that in an aqueous solution. The diffusion coefficient was 16 and 46% smaller than that in an aqueous solution for 3% NIPA and NIPA‐AA gels at 25 °C, respectively. As a result of the volume phase transition, after the gel collapses, no significant changes in the diffusion coefficient values were observed for NIPA‐AA gels. However, for NIPA gels, the diffusion coefficient of a probe decreases approximately two orders of magnitude. The volume phase transition also resulted in a change of the concentration of a probe in the collapsed gel phase. The concentration of Fc(MeOH)2 in collapsed NIPA gel was as much as 4.5 times higher than that in the original swollen gel, while for NIPA‐AA gel that increase in concentration was only 20%.
Grafted Silicas in Electroanalysis: Amorphous Versus Ordered Mesoporous Materials
Authors: Walcarius Alain , Etienne Mathieu , Sayen Stéphanie , Lebeau Bénédicte 
Published: April 2003

AbstractThis work reports the enhanced response of electrodes modified with ordered mesoporous silica‐based materials, as compared to corresponding amorphous materials, in case of open‐circuit accumulation and voltammetric detection of a target analyte. Several porous silica samples grafted with either thiol or ammonium groups, displaying high surface areas with various structural characteristics and different pore sizes, have been examined with respect to their ability to concentrate HgII species. Better accessibility to the binding sites and faster diffusion processes in the interior of grafted silicas have been observed for the ordered samples prepared by micelle‐templating because they contain channels of regular size, which are less tortuous than the irregular pore systems in amorphous materials. When applied in electrochemical detection of HgII after preconcentration, the ordered solids gave rise to voltammetric signals higher by more than one order of magnitude in comparison to the amorphous organically‐modified silicas. This rather new class of materials, which can be easily produced as ordered organic‐inorganic hybrids, is expected to improve the performance of silica‐modified electrodes in various fields of electroanalysis.
Flow‐Injection Analysis of Residual Glucose in Wines Using a Semiautomatic Analyzer Equipped with a Prussian Blue‐Based Biosensor
Authors: Ulasova E. A. , Micheli L. , Vasii L. , Moscone D. , Palleschi G. , Vdovichev S. V. , Zorin A. V. , Krutovertsev S. A. , Karyakina E. E. , Karyakin A. A. 
Published: April 2003

AbstractThe Prussian Blue modified glassy‐carbon (GC) electrode assembled with glucose oxidase (GOD) immobilized in Nafion on the top of the electrode surface area has been inserted in a wall‐jet cell connected to a semiautomatic analyzer, which controls all the operations for carrier buffer, flow and sample injection. The Prussian Blue based glucose biosensor inserted in the FIA analyzer has shown linear response to glucose at an applied potential of 0.0 V (Ag/AgCl) in the range of 10−6–10−3 M. Residual glucose has been detected in red and white wines. A dilution of 1 : 1000 has been used for all the wines tested. Neither matrix effect, nor electrochemical interferences were observed. A comparison with a spectrophotometric glucose kit gave excellent correlation for levels of glucose detected. FIA analyzer compared with the standard analytical kit resulted in simplified procedures and a reduced time for the analysis.
Determination of Mobile Thallium in Soil by Flow Injection Differential Pulse Anodic Stripping Voltammetry
Authors: Lukaszewski Zenon , Karbowska Bozena , Zembrzuski Wlodzimierz 
Published: April 2003

AbstractA procedure for the determination of mobile thallium in soil has been developed. Free thallium(I) was extracted with deionized water, while the sorbed and exchangeable metal was extracted with 1 M ammonium nitrate. Thallium in extracts was determined by differential‐pulse anodic stripping voltammetry in a flow‐injection system with medium circulation. 0.05 M EDTA was the base electrolyte. The procedure was applied for the determination of mobile thallium in a sample of ground from a waste dump which was a potential source of thallium pollution. The total concentration of thallium in the sample was 17.9 μg g−1. 3.97±0.25% of total thallium was found to be water soluble and 12.4±1.1% was sorbed and exchangeable. An attempt to determine the thallium bound to the carbonate fraction failed because of the high accumulation of interfering lead in this fraction. A single extraction cycle recommended by the literature was not sufficient to extract the whole thallium content of the fraction. Minor rivers of the area of the waste dump have a thallium concentration higher by two orders of magnitude than in reference rivers.