bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metallionen‐Gitterarchitekturen: funktionelle supramolekulare Metallkomplexe
Authors: Ruben Mario , Rojo Javier , Romero‐Salguero Francisco J. , Uppadine Lindsay H. , Lehn Jean‐Marie 
Published: June 2004

AbstractJüngste Entwicklungen auf dem Gebiet der supramolekularen Koordinationschemie haben Übergangsmetallkomplexe mit Gitterstruktur ins Blickfeld der Forschung gerückt. Die Synthesen dieser komplexen molekularen Einheiten beruhen auf Selbstorganisationsprozessen, in denen die Zielverbindungen durch Koordination organischer Liganden an Metallionen in einer Stufe aus einer Vielzahl von Komponenten thermodynamisch gesteuert aufgebaut werden. Die organischen Liganden und die Metallionen bestimmen die photophysikalischen, elektrochemischen und magnetischen Eigenschaften der Gitterkomplexe, zusätzlich können jedoch auch “kollektive” Eigenschaften auftreten. Funktionelle Gitterkomplexe sind interessant für die Nanotechnologie, z. B. hinsichtlich der Entwicklung einer (supra)molekularen Informationsspeicherung und ‐verarbeitung. Das Aufbringen dieser Komplexe auf Oberflächen führt zu ausgedehnten matrixartigen Anordnungen von Metallionen mit bisher unerreichten Dichten adressierbarer Elemente.
Grid‐Type Metal Ion Architectures: Functional Metallosupramolecular Arrays
Authors: Ruben Mario , Rojo Javier , Romero‐Salguero Francisco J. , Uppadine Lindsay H. , Lehn Jean‐Marie 
Published: June 2004

AbstractRecent advances in supramolecular coordination chemistry allow access to transition‐metal complexes of grid‐type architecture comprising two‐dimensional arrays of metal ions connecting a set of organic ligands in a perpendicular arrangement to generate a multiple wiring network. General design principles for these structures involve the thermodynamically driven synthesis of complex discrete objects from numerous molecular components in a single overall operation. Such supramolecular metal ion arrays combine the properties of their constituent metal ions and ligands, showing unique optical, electrochemical, and magnetic behavior. These features present potential relevance for nanotechnology, particularly in the area of supramolecular devices for information storage and processing. Thus, a dense organization of addressable units is represented by an extended “grid‐of‐grids” arrangement, formed by interaction of grid‐type arrays with solid surfaces.
A Synthetic Antithrombin III Binding Pentasaccharide Is Now a Drug! What Comes Next?
Authors: Petitou Maurice , van Boeckel Constant A. A. 
Published: June 2004

AbstractHeparin is a sulfated glycosaminoglycan isolated from animal organs that has been used clinically as an antithrombotic agent since the 1940s. In the early 1980s it was discovered that a unique pentasaccharide domain in some heparin chains activates antithrombin III (AT‐III), a serine protease inhibitor that blocks thrombin and factor Xa in the coagulation cascade. Sanofi‐Synthélabo and Organon developed a synthetic analogue of this pentasaccharide. The resulting antithrombotic drug arixtra, which went on the market in the USA and Europe in 2002, shows superior antithrombotic activity and brings about AT‐III‐mediated activity against factor Xa exclusively. Structure‐based design has subsequently led to analogues with longer‐lasting activity, such as idraparinux, as well as novel conjugates and long oligosaccharides with specific anti‐Xa and antithrombin activities. The new drug candidates are more selective in their mode of action than heparin and less likely to induce thrombocytopenia.
Acute exposure to 930 MHz CW electromagnetic radiation in vitro affects reactive oxygen species level in rat lymphocytes treated by iron ions
Authors: Zmyślony Marek , Politanski Piotr , Rajkowska Elżbieta , Szymczak Wieslaw , Jajte Jolanta 
Published: June 2004

AbstractThe aim of this study was to test the hypothesis that the 930 MHz continuous wave (CW) electromagnetic field, which is the carrier of signals emitted by cellular phones, affects the reactive oxygen species (ROS) level in living cells. Rat lymphocytes were used in the experiments. A portion of the lymphocytes was treated with iron ions to induce oxidative processes. Exposures to electromagnetic radiation (power density 5 W/m2, theoretical calculated SAR = 1.5 W/kg) were performed within a GTEM cell. Intracellular ROS were measured by the fluorescent probe dichlorofluorescin diacetate (DCF‐DA). The results show that acute (5 and 15 min) exposure does not affect the number of produced ROS. If, however, FeCl2 with final concentration 10 μg/ml was added to the lymphocyte suspensions to stimulate ROS production, after both durations of exposure, the magnitude of fluorescence (ROS level during the experiment) was significantly greater in the exposed lymphocytes. The character of the changes in the number of free radicals observed in our experiments was qualitatively compatible with the theoretical prediction from the model of electromagnetic radiation effect on radical pairs. Bioelectromagnetics 25:324–328, 2004. © 2004 Wiley‐Liss, Inc.
The effect of oscillating low intensity magnetic field on the Na+, K+, Ca++, and Mg++ concentrations in the maternal and fetal circulation of the dually perfused human placental cotyledon
Authors: Łopucki Maciej , Czekierdowski Artur , Rogowska Wanda , Kotarski Jan 
Published: June 2004

AbstractDual‐sided perfusions of the human placental cotyledon in vitro were used to study effects of low intensity magnetic fields (MFs) of 2 mT, 50 Hz (E1, 10 perfusions) and 5 mT, 50 Hz (E2, 10 perfusions). In the control group C (10 experiments) no field was used. Perfusions lasted 180 min each. Increased release of calcium ions from the placental cotyledon was found in the fetal circulation during perfusion when the 2 mT, 50 Hz MF was used. No changes in the release of sodium and magnesium ions were observed compared to the control group. The 5 mT, 50 Hz oscillating MF intensified the release of sodium ions from the perfused cotyledon both to the fetal and maternal circulation up to the 150th min of the experiment. Increased release of magnesium ions was observed only to the fetal circulation between 120 and 180 min and of calcium ions to the fetal circulation between 60 and 180 min. No significant differences in K concentrations were found between the control and MF exposed cotyledons under conditions of these experiments. Bioelectromagnetics 25:329–337, 2004. © 2004 Wiley‐Liss, Inc.
Effect of a 50 Hz electric field on plasma ACTH, glucose, lactate, and pyruvate levels in stressed rats
Authors: Harakawa Shinji , Takahashi Ikuo , Doge Fuyuki , Martin David E. 
Published: June 2004

AbstractThe effect of extremely low frequency electric field (EF) on stress induced changes of plasma ACTH, glucose, lactate, and pyruvate levels was examined in ovariectomized rats. The rats were exposed to 50 Hz EF (17500 V/m) for 60 min and were restrained for the latter half (30 min) of the EF exposure period. The restraint stress significantly increased the plasma ACTH and glucose levels (P < .05: Student's t test). Restraint induced increase of plasma ACTH and glucose levels tended to be suppressed by exposure to the EF. Meanwhile, the EF exposure also affected plasma lactate level. Thus, the EF exposure significantly decreases plasma lactate levels in the stressed rats (P < .05: Student's t test). Although the precise mechanisms in the restraint dependent alteration in plasma ACTH, glucose, lactate, and pyruvate levels are not fully understood, our results demonstrate that the 50 Hz EF alter both stress responses and energy metabolism in stressed rats. Bioelectromagnetics 25:346–351, 2004. © 2004 Wiley‐Liss, Inc.
Experimental validation of a statistical model for evaluating the past or future magnetic field exposures of a population living near power lines
Authors: Turgeon Alain , Bourdages Michel , Levallois Patrick , Gauvin Denis , Gingras Suzanne , Deadman Jan Erik , Goulet Daniel L. , Plante Michel 
Published: June 2004

AbstractThis study was designed to provide an experimental validation for a statistical model predicting past or future exposures to magnetic fields (MF) from power lines. The model estimates exposure, combining the distribution of ambient MF in the absence of power lines with the distribution of past or future MF produced by power lines. In the study, validation is carried out by comparing exposures predicted by the model with the actual measurements obtained from a large‐scale epidemiological study. The comparison was made for a group of 220 women living near a 735 kV power line. Knowing that the individual arithmetic means of MF exposures follow a log‐normal distribution, the Pearson correlation between the log‐transformed measured means and the calculated ones was determined and found to be 0.77. Predicted values of MF exposures were slightly lower than measured values. The calculated geometric mean of the group was 0.33 μT, compared to 0.38 μT for the measured geometric mean. The present study shows good agreement between the measured MF exposure of an individual inside a house near a 735 kV line and the MF exposure calculated using a statistical model. Bioelectromagnetics 25:374–379, 2004. © 2004 Wiley‐Liss, Inc.
Influence of 50 Hz Frequency Sinusoidal Magnetic Field on the Blood‐Brain Barrier Permeability of Diabetic Rats
Authors: Öztaş Baria , Kalkan Tunaya , Tuncel Handan 
Published: June 2004

AbstractThe combined effects of diabetes and a 50 Hz, 5 mT RMS flux density sinusoidal magnetic field for 8 h a day, for 21 consecutive days on the permeation of Evans‐blue dye through the blood‐brain barrier were studied in male Wistar albino rats. Our results suggest that magnetic field has no effect on the blood‐brain barrier permeability in normoglycemic animals, but that diabetic rats are vulnerable to magnetic fields. Bioelectromagnetics 25:400–402, 2004. © 2004 Wiley‐Liss, Inc.
Tragverhalten von textilbewehrtem Beton
Authors: Hegger Josef , Will Norbert , Curbach Manfred , Jesse Frank 
Published: June 2004

AbstractDas Tragverhalten von textilbewehrtem Beton ähnelt dem von Stahlbeton, wird aber deutlicher durch den Verbund der textilen Bewehrung mit dem Feinbeton geprägt. Neben dem Materialverhalten werden deshalb das Rißbildungsverhalten, die Bruchtragfähigkeit, das Verformungsverhalten und die Dauerhaftigkeit gezielt untersucht. Mit den daraus abgeleiteten Nachweiskonzepten und Bemessungsmodellen wurden bereits erste Anwendungen realisiert. Im Beitrag werden die wesentlichen hierzu vorliegenden Ergebnisse zusammenfassend dargestellt.
Mechanisms of Fabric Reinforcement of Cement Matrices
Authors: Peled Alva , Bentur Arnon 
Published: June 2004

AbstractThe present paper discusses the mechanisms involve in fabric‐cement composites focusing on the effects of fabric geometry and the properties of the yarns. It was found that the geometry of a given fabric could enhance the bonding and enable one to obtain strain hardening behavior from low modulus yarn fabrics, due to the special shape of the yarn induced by the fabric. On the other hand, variations of the geometry in a fabric could drastically reduce the efficiency, resulting in a lower strengthening effect of the yarns in the fabric, relative to single yarns not in a fabric form. Therefore, in cement composites the fabrics can not be viewed simply as a means for holding together continuous yarns to be readily placed in the matrix, as is the case in composites with polymer matrix.
Numerische Modellierung von textilbewehrtem Beton
Authors: Chudoba Rostislav , Graf Wolfgang , Meskouris Konstantin , Zastrau Bernd 
Published: June 2004

AbstractDer Artikel gibt einen kurzen Überblick über die aktuellen Ansätze zur Modellierung des textilbewehrten Betons mit dem Schwerpunkt auf den besonderen Anforderungen, die sich aufgrund der hochgradigen Heterogenität der Materialstruktur stellen. Mit Hilfe der präsentierten Modelle können experimentelle Ergebnisse detailliert interpretiert und verallgemeinert werden, so daß eine zielgerichtete Weiterentwicklung des Verbundwerkstoffes Textilbeton ermöglicht wird.
Vorgespannte Bauteile aus textilbewehrtem Beton
Authors: Krüger Markus , Reinhardt Hans‐Wolf 
Published: June 2004

AbstractDer vorliegende Beitrag zeigt, daß die Tragfähigkeit und die Steifigkeit eines textilbewehrten Bauteils durch Vorspannung deutlich erhöht werden kann. Besonderheiten, die bei der Vorspannung textiler Bewehrung beachtet werden müssen, werden herausgestellt. Neben den Anforderungen an die Textilien selbst werden insbesondere Fragen zur Einspannung, zum Verbund von textiler Bewehrung im Beton und auch Aspekte zur möglichen Bemessung angesprochen. Der innere und äußere Verbund des Textils sowie die notwendige Verbesserung des inneren Verbunds durch geeignete Maßnahmen sind in diesem Zusammenhang von großer Bedeutung.
Technische Textilien zur Bewehrung von Betonbauteilen
Authors: Offermann Peter , Engler Thomas , Gries Thomas , Roye Andreas 
Published: June 2004

AbstractDie Eigenschaften von textilbewehrtem Beton werden maßgeblich durch die Menge, die Eigenschaften und die Anordnung der eingesetzten Fasermaterialien bestimmt. An den Faserstoff und seine Aufmachung bestehen daher vielfältige Anforderungen. Nicht zuletzt muß das Fasermaterial preiswert und seine textiltechnologische Verarbeitbarkeit gegeben sein.Die Auswahl der textilen Bewehrung hängt auch davon ab, ob das Bewehrungsmaterial dem alkalischen Milieu des Betons ohne wesentliche Eigenschaftsverluste widerstehen kann. Daneben gehören eine geringe Relaxation bei Dauerbelastung sowie ein günstiges und vor allem gleichbleibendes Verbundverhalten gegenüber der Betonmatrix zu den Anforderungen.Der Beitrag stellt die heute verfügbaren Materialien einschließlich Herstellungsprozeß und Eigenschaften vor.
The Direct Catalytic Asymmetric α‐Aminooxylation Reaction: Development of Stereoselective Routes to 1,2‐Diols and 1,2‐Amino Alcohols and Density Functional Calculations
Authors: Córdova Armando , Sundén Henrik , Bøgevig Anders , Johansson Mikael , Himo Fahmi 
Published: June 2004

AbstractProline‐catalyzed direct asymmetric α‐aminooxylation of ketones and aldehydes is described. The proline‐catalyzed reactions between unmodified ketones or aldehydes and nitrosobenzene proceeded with excellent diastereo‐ and enantioselectivities. In all cases tested, the corresponding products were isolated with >95 %ees. Methyl alkyl ketones were regiospecifically oxidized at the methylene carbon atom to afford enantiomerically pure α‐aminooxylated ketones. In addition, cyclic ketones could be α,α′‐dioxidized with remarkably high selectivity, furnishing the corresponding diaminooxylated ketones with >99 %ees. The reaction mechanism of the proline‐catalyzed direct asymmetric α‐aminooxylation was investigated, and we performed density functional theory (DFT) calculations in order to investigate the nature of the plausible transition states further. We also screened other organocatalysts for the asymmetric α‐oxidation reaction and found that several proline derivatives were also able to catalyze the transformation with excellent enantioselectivities. Moreover, stereoselective routes for the synthesis of monoprotected vicinal diols and hydroxyketones were found. In addition, short routes for the direct preparation of enantiomerically pure epoxides and 1,2‐amino alcohols are presented. The direct catalytic α‐oxidation is also a novel route for the stereoselective preparation of β‐adrenoreceptor antagonists.
Growth and characterization of superconductive Nd2‐xCexCuO4‐y single crystals
Authors: Jia L. S. , Chen X. L. , Yang W. , Yan X. L. 
Published: June 2004

AbstractNd2‐xCexCuO4‐y single crystals with different x values have been successfully grown by Traveling Solvent Floating Zone method (TSFZ). Electronic properties of Nd2‐xCexCuO4‐y single crystals with various x have been studied in detail. The results show that superconductivity can be found in crystals with x > 0.1 (0.13‐0.18) directly grown at oxygen‐reduced atmosphere without post‐annealed, while no superconductivity appears in crystals with x < 0.1 at the same atmosphere. It is also found that, the segregation coefficient of Ce is determined to be 0.946 and transition temperature Tc (onset) reaches maximum value of 23.5 K at nominal composition x = 0.165. With further increase of Ce concentration, transition temperature of single crystals declines due to the precipitation of secondary Phases. In addition, the variation of lattice constants of Nd2‐xCexCuO4‐y single crystals with different x is also given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and morphology of the single crystals of thermoelectric oxide material NaxCoO2
Authors: Thinaharan C. , Aswal D. K. , Singh A. , Bhattacharya S. , Joshi N. , Gupta S. K. , Yakhmi J. V. 
Published: June 2004

AbstractWe have grown single crystals of recently discovered thermoelectric oxide material NaxCoO2 using NaCl flux. Crystals of sizes upto 1.5 x 1.5 x 1.5 mm3 having different morphological habits were reproducibly grown. The atomic force microscopic studies show that along c‐axis crystals grow via 2D layer‐by‐layer mechanism. The X‐ray diffraction analyses show that grown crystals are rich in Na content as compared to the starting charge indicating that NaCl flux also acts as a source of Na. The resistivity of the crystals exhibited a linear temperature dependence in the region between 30 and 300 K. © 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
A study of primary nucleation of calcium oxalate monohydrate: II. Effect of urinary species
Authors: El‐Shall H. , Jeon J.‐H. , Abdel‐Aal E. A. , Khan S. , Gower L. , Rabinovich Y. 
Published: June 2004

AbstractKidney stones consist of various organic and inorganic compounds. Calcium oxalate monohydrate (COM) is the main inorganic constituent of kidney stones. However, the mechanisms for the formation of calcium oxalate kidney stones are not well understood. In this regard, there are several hypotheses including nucleation, crystal growth and/or aggregation of formed COM crystals. The effect of some urinary species such as oxalate, calcium, citrate, and protein on nucleation and crystallization characteristics of COM is determined by measuring the weight of formed crystals and their size distributions under different chemical conditions, which simulate the urinary environment. Statistical experimental designs are used to determine the interaction effects among various factors. The data clearly show that oxalate and calcium promote nucleation and crystallization of COM. This is attributed to formation of a thermodynamically stable calcium oxalate monohydrate resulting from supersaturation. Citrate, however, inhibits nucleation and further crystal growth. These results are explained on the basis of the high affinity of citrate to combine with calcium to form soluble calcium citrate complexes. Thus, citrate competes with oxalate ion for binding to calcium cations. These conditions decrease the amount of free calcium ions available to form calcium oxalate crystals. In case of protein (mucin), however, the results suggest that no significant effect could be measured of mucin on nucleation and crystal growth. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal properties of nano crystalline CdS
Authors: Raji P. , Sanjeeviraja C. , Ramachandran K. 
Published: June 2004

AbstractNano CdS samples are synthesized by precipitation method for different growth conditions. Thermal diffusivity and conductivity on these nano CdS are measured by photo acoustic technique. The results are compared with bulk and discussed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Collective Dust‐Dust Attraction in Strong Magnetic Field
Authors: Tsytovich V. N. , Koller J. 
Published: June 2004

AbstractIt is shown that the collective dust‐dust attraction is enhanced by strong magnetic fields larger then the critical magnetic field determined be the condition that the Lorentz force acting on ions is larger than the friction of ions on dust grains related with the dust drag. It is demonstrated that with an increase of the magnetic field the deepness of the attraction potential well is increased in all directions to the magnetic field, that the distance of the minimum of the potential well along the magnetic filed (in both directions) is changed only slightly while the distance of the minimum of the attraction potential well is substantially decreased for directions perpendicular to the magnetic field. This means that the structures formed by attraction forces such as plasma crystals will be compressed perpendicular to the magnetic field (inter‐dust distance becomes smaller) and that the melting transition temperature should increased with an increase of the strength of the magnetic field. Numerical results are presented for dependence of the attraction potential well on the ratio of the strength of the magnetic field to the critical magnetic field strength, on the parameter P = ndZd/ni (nd and ni being the dust and ion densities respectively) and on the temperature ratio τ = Ti/Te (Te and Ti being the electron and ion temperatures respectively). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Effective Liapunov Exponent with Increasing Stochasticity for Tokamap
Authors: Maluckov A. 
Published: June 2004

AbstractThe effective Liapunov exponent statistical description of tokamap with increasing stochasticity is numerically developed. As the 2D Hamiltonian mapping, tokamap is characterized by the two Liapunov exponents lx = −lθ ≥ 0, and 2D Liapunov exponent L = 0. The time development of the effective Liapunov exponent Lxe, the number of trajectories with lx > 0, Np, and the statistics of the non‐negative Liapunov exponents are numerically considered following the test ensemble of N = 10000 trajectories. The sticking to regular structures in the phase space of tokamap, which is associated with the non‐positive Liapunov exponent lx, clearly effects its statistics. Thus, the behavior of the effective Liapunov exponent Lxe may be taken as one of the qualitative measures of the degree of stochasticity for the observed mapping. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus
Authors: Greiner F. , Block D. , Piel A. 
Published: June 2004

AbstractThe spatio‐temporal dynamics of large‐scale structures in curved magnetic field of simple magnetized torus (SMT) are presented. The experiments are performed in the SMT BLAAMANN and employ the techniques of conditional averaging (CA) and cross‐correlation (CCF) of Langmuir probe data. By means of a detailed comparison of radio‐frequency and thermionic discharges, it is shown that general features of the observed large‐scale structures are independent of the discharge mechanism. Further, the observed large scale structures have a pronounced spatio‐temporal periodicity, which suggests a description as mode‐like. The conjectured relationship between the observed coherent structures and the inverse energy cascade is therefore questioned again. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma Modelling for the PSI Linear Plasma Device
Authors: Kastelewicz H. , Fussmann G. 
Published: June 2004

AbstractDeuterium discharges in the PSI device have been modelled using the coupled package of the B2 hydrodynamic plasma code and the Eirene Monte‐Carlo neutral code. Radial and axial plasma profiles have been calculated for different magnetic field configurations, various radial diffusion laws and for different values of the flux limiter in the parallel electron heat conduction law used in the B2 code. The results are compared with experimental findings. The axial variation of the magnetic field strength is found to have an important influence on the plasma state via the axial plasma flow which closely resembles the neutral gas streaming through a series of laval nozzles. For particular magnetic field configurations, an appropriate ansatz for the parallel electron heat conduction turns out to be a crucial point for the applicability of hydrodynamic models to linear devices like the plasma generator PSI. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)