bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Concept for the Efficient Synthesis of Chiral Phosphorus−Nitrogen−Carbon Cage Compounds
Authors: Hoffmann Nils , Wismach Catleen , Ernst Ludger , Schiebel Hans‐Martin , Jones Peter G. , Streubel Rainer 
Published: April 2003

AbstractA new concept for the efficient synthesis of a chiral phosphorus‐nitrogen‐carbon cage‐compound is reported, which is comprised of a high‐yield three‐step procedure starting from a P‐Cp*‐substituted 2H‐azaphosphirene complex. Thermolysis of a solution of the latter complex in the presence of Ph3PNCN and DMAD afforded the P‐Cp*‐substituted 2H‐1,2‐azaphosphole complex 11 in a clean reaction; a further reaction at 75 °C with DMAD produced complex 12 via an intermolecular Diels−Alder reaction of the Cp* group. A subsequent intramolecular Diels−Alder reaction of 12, at 120 °C, yielded the title compound, complex 13, in quantitative yields. Elemental analyses and detailed (solution) NMR spectroscopic and MS investigations confirmed all complexes. Furthermore, solid state structures of complexes 11 and 13 were established by X‐ray single crystal structure analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Solvothermal Synthesis of a Layered Open‐Framework Chlorocadmium Oxalate, Cd2(C2O4)0.5Cl3NaCl·4H2O (Eur. J. Inorg. Chem. 9/2003)
Authors: Vaidhyanathan R. , Natarajan Srinivasan , Rao C. N. R. 
Published: April 2003

AbstractThe cover picture shows a schematic illustration of the unusual inorganic‐organic hybrid structures (upper right) formed by linking of the inorganic building units through organic linkers. The structures of two different compounds (bottom) containing the inorganic cadmium chloride chains (upper left corner) linked by oxalate and piperazine moieties into two and three dimensions are also shown. Color scheme: Cd − yellow; Cl − green; O − red; N − violet; C − blue. Details are discussed in the article by C. N. R. Rao et al. on p. 1675 ff.
Binding Curve from Normalized Limiting Currents of Labile Heterogeneous Metal‐Macromolecular Systems. The Case of Cd/Humic Acid
Authors: Companys Encarnació , Puy Jaume , Torrent Marià , Galceran Josep , Salvador José , Garcés Josep Lluís , Mas Francesc 
Published: April 2003

AbstractA set of titrations of different amounts of humic acid with cadmium are performed at pH 6.0 and fixed ionic strength (0.1 M KNO3). Both reverse pulse polarograms, which minimize the electrodic adsorption effects on the limiting current, and potentiometric measurements with an ion selective electrode are recorded along the titrations. The free metal concentration is determined from the polarographic measurement by means of an iterative numerical method recently developed. The resulting binding curve is found to agree very well with the one obtained through the potentiometric data obtained along the same titration. After application of the Donnan model to correct for polyelectrolytic effects, different complexation isotherms have been used to fit the specific binding. Complexation parameters for the Cd/HA system obtained with a Langmuir‐Freundlich and Gaussian isotherms are briefly discussed.
Development of a Multiresidue Liquid Chromatography Method with Electrochemical Detection (HPLC‐ECD) for the Determination of Macrolide Antibiotics
Authors: González de la Huebra María José , Bordin Guy , Rodríguez Adela Rosa 
Published: April 2003

AbstractA multiresidue high performance liquid chromatography procedure with electrochemical detection (amperometric) (HPLC‐ECD) using a C18 narrow bore column was fully optimized for the separation of a standard mixture of macrolides. Up to five macrolides, josamycin (JOS), kitasamycin (KIT), rosamicin (ROS) roxithromycin (ROX) and oleandomycin (OLE), the latter being selected as internal standard for the quantification, were properly separated using an isocratic elution mode. The influence of classical chromatographic and instrumental parameters was investigated in order to optimize them before the calibration assay. The method was succesfully applied to the determination of ROS and ROX in human urine.
Bioelectrocatalytical Detection of H2O2 with Different Forms of Horseradish Peroxidase Directly Adsorbed at Polycrystalline Silver and Gold
Authors: Ferapontova Elena , Gorton Lo 
Published: April 2003

AbstractThe bioelectrocatalytical reduction of H2O2 based on direct electron transfer (ET) between polycrystalline silver and the heme containing active site of horseradish peroxidase (HRP) is studied and compared with that obtained at gold. Native HRP and recombinant wild type HRP, containing additionally a six‐histidine tag at the N‐terminus, NHisrHRP, have been used for adsorptive modification of the electrodes. The histidine sequences, introduced into the peroxidase structure by genetic engineering of recombinant HRP using an E. coli expression system, were supposed to affect adsorption/orientation of the enzyme at the electrode surface. The variations in direct ET efficiency when changing from gold to silver, as well as from native HRP to NHisrHRP are analyzed and discussed, specifically, the high ET rates obtained with NHisrHRP‐modified preoxidized gold and silver electrodes, though accompanied by extremely rapid loss of the biolectrocatalytical activity of the latter (silver) in direct (but not mediated) ET. The advantages and drawbacks of the studied HRP‐electrode systems for the electroanalytical detection of H2O2 are considered.
Ceramic Carbon Electrode Modified with Butyloferrocene
Authors: Saczek‐Maj Monika , Opallo Marcin 
Published: April 2003

AbstractCeramic carbon electrode modified with butyloferrocene was prepared and studied. The electrode consists of graphite powder, homogeneously dispersed in hydrophobic silica matrix. The latter was obtained from organically modified silicate – methyltrimethoxysilane by sol‐gel process. After gelation and drying it was filled with redox liquid – butyloferrocene by immersion. The properties of the electrode were investigated by cyclic voltammetry and chronoamperometry in aqueous salt solution of different concentration. The cyclic polarization of the electrode in aqueous electrolyte results in peak shaped voltammogram, stable during continuous potential cycling. The modification of the electrode with butyloferrocene diluted by hydrophobic non‐electroactive solvent like hexadecane leads to a decrease of the current. The specific voltammogram features were attributed to the redox process of butyloferrocene. The magnitude of the current is proportional to the aqueous electrolyte concentration. It has been concluded that the electrooxidation of redox liquid within hydrophobic silicate matrix is followed by anion transfer from aqueous phase. The electrode process occurs at the three phase junction formed by graphite particles and liquid organic‐aqueous interface supported by hydrophobic silicate.
Electrophoresis of biological cells: Charge‐regulation and multivalent counterions association model
Authors: Hsu Jyh‐Ping , Hsieh Tien‐Shiang , Young Tai‐Horng , Tseng Shiojenn 
Published: April 2003

AbstractThe electrophoresis of a biological cell is analyzed theoretically. An entity, which is of amphoteric nature, is used to simulate its electrophoretic behavior. To reflect conditions of practical interest, we assume that the liquid phase contains mixed (a:b)+(c:b) electrolytes, where a and c are the valences of cations, and b is the valence of anions. We consider the case where the surface of a cell contains both bivalent acidic and monovalent basic functional groups, the dissociation/association of them yields fixed surface charge, and the multivalent cations in the liquid phase are allowed to combine with dissociated acidic functional groups, which has the effect of lowering the charge density on cell surface. The electrophoretic behaviors of a cell under various conditions are illustrated. The results obtained can be used to identify the types of functional groups that may be present on cell surface. On the other hand, if the surface functional groups involved in cell electrophoresis are known, then their density and the associated dissociation/association constants can be estimated from experimental data.
Direct and specific recognition of glycosaminoglycans by antibodies after their separation by agarose gel electrophoresis and blotting on cetylpyridinium chloride‐treated nitrocellulose membranes
Authors: Maccari Francesca , Volpi Nicola 
Published: April 2003

AbstractA method for the immunodetection of several natural complex polysaccharides (glycosaminoglycans) after their separation by conventional agarose gel electrophoresis, blotting and immobilizing on nitrocellulose membranes derivatized with the cationic detergent cetylpyridinium chloride (CPC), and direct and specific immunodetection by antibodies is described. This new approach is based on the principles that were used to develop the Western blot, and is applied to the separation of the glycosaminoglycans purified from normal human urine. After migration in agarose gel electrophoresis, chondroitin sulfate samples of different origin were blotted and transferred onto nitrocellulose membranes treated with CPC. Immunodetection was performed using the anti‐chondroitin‐6‐sulfate antibody that specifically recognizes intact chondroitin‐6‐sulfate. By calculating the ratio between the antibody staining (epitope) and alcian blue staining (mass), the epitope density expressed as a percentage, i.e., the number of repetitive epitopes per mass, was obtained. These values were in agreement with the quantitation of 6‐sulfated groups of chondroitin sulfate performed by the evaluation of unsatured disaccharide‐6‐sulfate (ΔDi6S) produced after treatment with chondroitinase ABC and separated by high‐performance liquid chromatography (HPLC). Furthermore, immunodetection of heparan sulfate was performed using the anti‐heparan sulfate antibody.
Chiral resolution of some environmental pollutants by capillary electrophoresis
Authors: Ali Imran , Gupta Vinod K. , Aboul‐Enein Hassan Y. 
Published: April 2003

AbstractThe chiral resolution of the environmental pollutants by capillary electrophoresis is reviewed. Various aspects of the chiral resolution such as chiral selectors, optimization of capillary electrophoresis conditions including composition of the background electrolyte (BGE), pH of the BGE, ionic strength of the BGE, structures and types of the chiral selectors, applied voltage, temperature, structures of the chiral pollutants, use of organic modifiers and other parameters are presented. Furthermore, detection, sample treatment, validation of the methods, and the chiral recognition mechanisms, have been discussed.
Comprehensive two‐dimensional separations based on capillary high‐performance liquid chromatography and microchip electrophoresis
Authors: Yang Xiuhan , Zhang Xiangmin , Li Aizhen , Zhu Shiyang , Huang Yiping 
Published: April 2003

AbstractA novel comprehensive two‐dimensional (2‐D) separation system coupling capillary high‐performance liquid chromatography (cHPLC) with microchip electrophoresis (chip CE) is demonstrated. Reversed‐phase cHPLC was used as the first dimension, and chip CE acted as the second dimension to perform fast sample transfers and separations. A valve‐free gating interface was devised simply by inserting the outlet‐end of LC column into the cross‐channel on a specially designed chip. A home‐made confocal laser‐induced fluorescence detector was used to perform on‐chip high‐sensitive detection. The cHPLC effluents were continuously delivered to the chip and pinched injections of the effluents every 20 seconds were employed for chip CE separation. Gradient elution of cHPLC was carried out to obtain the high‐efficiency separation. Free‐zone electrophoresis was performed with triethylamine buffer to achieve high‐speed separation and prevent sample adsorption. Such a simple‐made comprehensive system was proved to be effective. The relative standard deviations for migration time and peak height of rhodamine B in 150 sample transfers were 3.2% and 9.8%, respectively. Peptides of the fluorescein isothiocyanate (FITC)‐labeled tryptic digests of bovine serum albumin were fairly resolved and detected with this comprehensive 2‐D system.
Estimation of fundamental periods of shear‐wall dominant building structures
Authors: Balkaya Can , Kalkan Erol 
Published: April 2003

AbstractShear‐wall dominant multistorey reinforced concrete structures, constructed by using a special tunnel form technique are commonly built in countries facing a substantial seismic risk, such as Chile, Japan, Italy and Turkey. In spite of their high resistance to earthquake excitations, current seismic code provisions including the Uniform Building Code (International Conference of Building Officials, Whittier, CA, 1997) and the Turkish Seismic Code (Specification for Structures to be Built in Disaster Areas, Ankara, Turkey, 1998) present limited information for their design criteria. In this study, consistency of equations in those seismic codes related to their dynamic properties are investigated and it is observed that the given empirical equations for prediction of fundamental periods of this specific type of structures yield inaccurate results. For that reason, a total of 80 different building configurations were analysed by using three‐dimensional finite‐element modelling and a set of new empirical equations was proposed. The results of the analyses demonstrate that given formulas including new parameters provide accurate predictions for the broad range of different architectural configurations, roof heights and shear‐wall distributions, and may be used as an efficient tool for the implicit design of these structures. Copyright © 2003 John Wiley & Sons, Ltd.
System identification of instrumented bridge systems
Authors: Arici Yalin , Mosalam Khalid M. 
Published: April 2003

AbstractSeveral recorded motions for seven bridge systems in California during recent earthquakes were analysed using parametric and non‐parametric system identification (SI) methods. The bridges were selected considering the availability of an adequate array of accelerometers and accounting for different structural systems, materials, geometry and soil types. The results of the application of SI methods included identification of modal frequencies and damping ratios. Excellent fits of the recorded motion in the time domain were obtained using parametric methods. The multi‐input/single‐output SI method was a suitable approach considering the instrumentation layout for these bridges. Use of the constructed linear filters for prediction purposes was also demonstrated for three bridge systems. Reasonable prediction results were obtained considering the various limitations of the procedure. Finally, the study was concluded by identifying the change of the modal frequencies and damping of a particular bridge system in time using recursive filters. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamic stiffness of foundation embedded in layered halfspace based on wave propagation in cones
Authors: Wolf John P. , Preisig Matthias 
Published: April 2003

AbstractAn Erratum has been published for this article in Earthquake Engineering & Structural Dynamics 33(6) 2004, 793.The dynamic stiffness of a foundation embedded in a multiple‐layered halfspace is calculated postulating one‐dimensional wave propagation in cone segments. In this strength‐of‐materials approach the sectional property of the cone segment increases in the direction of wave propagation. Reflections and refractions with waves propagating in corresponding cone segments occur at layer interfaces. Compared to rigorous procedures the novel method based on cone segments is easy to apply, provides conceptual clarity and physical insight in the wave propagation mechanisms.This method postulating one‐dimensional wave propagation in cone segments with reflections and refractions at layer interfaces is evaluated, calculating the dynamic stiffness of a foundation embedded in a multiple‐layered halfspace. For sites resting on a flexible halfspace and fixed at the base, engineering accuracy (deviation of ±20%) is achieved for all degrees of freedom with a vast parameter variation. The behaviour below the cut‐off frequency in an undamped site fixed at its base is also reliably predicted. The accuracy is, in general, better than for the method based on cone frustums, which can lead to negative damping. Copyright © 2003 John Wiley & Sons, Ltd.
Application of non‐linear multiple tuned mass dampers to suppress man‐induced vibrations of a pedestrian bridge
Authors: Poovarodom Nakhorn , Kanchanosot Sopak , Warnitchai Pennung 
Published: April 2003

AbstractThis paper presents an application of multiple tuned mass dampers (MTMDs) with non‐linear damping devices to suppress man‐induced vibrations of a 34m long pedestrian bridge. The damping force generated by each of these damping devices is simply a drag force from liquid acting on an immersed section. The quadratic non‐linear property of these devices was directly determined from free vibration tests of a simple laboratory set‐up. Dynamic models of the bridge and pedestrian loads were constructed for numerical investigation based on field measurement data. The control effectiveness of non‐linear MTMDs was examined along with its sensitivity against estimation errors in the bridge's natural frequency and magnitude of pedestrian load. The numerical results indicated that the optimum non‐linear MTMD system was as effective and robust as its linear counterpart. Then, a six‐unit non‐linear MTMD system was designed, constructed, and installed on the bridge. Field measurements after the installation confirmed the effectiveness of non‐linear MTMDs, and the measurement results were in good agreement with numerical predictions. After the installation, the average damping ratio of the bridge was raised from 0.005 to 0.036 and the maximum bridge accelerations measured during walking tests were reduced from about 0.80–1.30 ms−2 to 0.27–0.40 ms−2, which were within an acceptable range. Copyright © 2003 John Wiley & Sons, Ltd.
Oncostatin M enhances the expression of prostaglandin E2 and cyclooxygenase‐2 in astrocytes: Synergy with interleukin‐1β, tumor necrosis factor‐α, and bacterial lipopolysaccharide
Authors: Repovic Pavle , Mi Kaihong , Benveniste Etty N. 
Published: April 2003

AbstractOncostatin M (OSM), a cytokine of the interleukin‐6 family, is expressed in rheumatoid arthritis, multiple sclerosis, multiple myeloma, and other inflammatory and neoplastic conditions. Prostaglandin E2 (PGE2), an eicosanoid also associated with inflammation and cancer, has recently been shown to induce OSM expression. We report here that OSM in turn induces PGE2 production by astrocytes and astroglioma cells. More importantly, in combination with the inflammatory mediators IL‐1β, tumor necrosis factor‐α, and lipopolysaccharide, OSM exhibits a striking synergy, resulting in up to 50‐fold higher PGE2 production by astrocytes, astroglioma, and neuroblastoma cell lines. Enhanced PGE2 production by OSM and IL‐1β treatment is explained by their effect on cyclooxygenase‐2 (COX‐2), an enzyme that catalyzes the committed step in PGE2 synthesis. Of the enzymes involved in PGE2 biosynthesis, only COX‐2 mRNA and protein levels are synergistically amplified by OSM and IL‐1β. Nuclear run‐on assays demonstrate that OSM and IL‐1β synergistically upregulate transcription of the COX‐2 gene, and the mRNA stability assay indicates that COX‐2 mRNA is posttranscriptionally stabilized by OSM and IL‐1β. To effect synergy on the PGE2 level, OSM signals in part through its gp130/OSMRβ receptor, since neutralizing antibodies against gp130 and OSMRβ, but not LIFRβ, decrease PGE2 production in response to OSM plus IL‐1β. SB202190 and U0126, inhibitors of p38 MAPK and ERK1/2 activation, respectively, inhibit IL‐1β and OSM upregulation of COX‐2 and PGE2, indicating that these MAPK cascades are utilized by both stimuli. This mechanism of PGE2 amplification may be active in brain pathologies where both OSM and IL‐1β are present, such as glioblastomas and multiple sclerosis. GLIA 42:433–446, 2003. © 2003 Wiley‐Liss, Inc.
Early onset of degenerative changes at nodes of Ranvier in alpha‐motor axons of Cntf null (−/−) mutant mice
Authors: Gatzinsky Kliment P. , Holtmann Bettina , Daraie Babak , Berthold Claes‐Henric , Sendtner Michael 
Published: April 2003

AbstractThe nodes of Ranvier are sites of specific interaction between Schwann cells and axons. Besides their crucial role in transmission of action potentials, the nodes of Ranvier and in particular the paranodal axon‐Schwann cell networks (ASNs) are thought to function as local centers in large motor axons for removal, degradation, and disposal of organelles. In order to test whether ciliary neurotrophic factor (CNTF), which is present at high levels in the Schwann cell cytoplasm, is involved in the maintenance of these structures, we have examined lumbar ventral root nerve fibers of alpha‐motor neurons by electron microscopy in 3‐ and 9‐month‐old Cntf null (−/−) mutant mice. Nerve fibers and nodes of Ranvier in 3‐month‐old Cntf−/− mutants appeared morphologically normal, except that ASNs were more voluminous in the mutants than in wild‐type control animals at this age. In 9‐month‐old Cntf−/− animals, morphological changes, such as reduction in nerve fiber and axon diameter, myelin sheath disruption, and loss of ASNs at nodes of Ranvier, were observed. These findings suggest that endogenous CNTF, in addition to its role in promoting motor neuron survival and regeneration, is needed for long‐term maintenance of alpha‐motor nerve fibers. The premature loss of paranodal ASNs in animals lacking CNTF, which seems to be a defect related to a disturbed interaction in the nodal region between the axon and its myelinating Schwann cells, could impede the maintenance of a normal milieu in the motor axon, preceding more general neuronal damage. GLIA 42:340–349, 2003. © 2003 Wiley‐Liss, Inc.
Effect of endothelin‐1 on astrocytic protein content
Authors: Hasselblatt Martin , Bunte Marion , Dringen Ralf , Tabernero Arantxa , Medina José M. , Giaume Christian , Sirén Anna‐Leena , Ehrenreich Hannelore 
Published: April 2003

AbstractThe astrocytic endothelin (ET) receptors, ETA and ETB, modulate calcium signaling and the astrocytic gap junctional network. The nonselective ET receptor ligand ET‐1 inhibits gap junction permeability, an effect that can be blocked by tolbutamide. This mechanism may play a role in pathophysiological conditions such as ischemic stroke, characterized by elevated tissue ET‐1 levels and hypertrophic‐appearing reactive astrocytes. Therefore, the effect of ET‐1 on cellular protein content was investigated in confluent once‐passaged rat astrocyte cultures under serum‐free conditions, by the Lowry method. Gap junction permeability was determined by the dye transfer technique. ET‐1 prevented the decrease in astrocytic protein content observed in controls. The effect of ET‐1 on cellular protein content was most pronounced in cultures seeded at high density, but it was attenuated in ETB‐deficient (sl/sl) astrocytes. This effect could be blocked by the nonselective ET antagonist LU 302872 (10 μM), as well as by the protein synthesis inhibitor cycloheximide (10 μM). This increase in astrocytic protein content was inhibited by the ATP‐sensitive K+ channel blocker tolbutamide, which also antagonized the ET‐1‐induced reduction of gap junction permeability and reversed the morphological changes observed in astrocytes upon ET‐1 treatment. Cytosine arabinoside (10 μM), a DNA synthesis blocker, inhibited the ET‐1‐induced BrdU uptake without affecting the ET‐1‐induced increase in astrocytic protein content. To conclude, ET‐1 induces an increase in astrocytic protein content as well as changes in astrocyte morphology in vitro. This hypertrophic response involves uncoupling of the astrocytic gap junctional network and is not dependent on DNA synthesis. GLIA 42:390–397, 2003. © 2003 Wiley‐Liss, Inc.