bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation of Genomic DNA from Mammalian Cells
Authors: Gilbert John R. , Vance Jeffrey M.
Published: June 2004

This unit describes simple, cost‐effective preparation of DNA from whole blood or cultured cells that yields high‐molecular‐weight DNA suitable for both Southern blotting and the polymerase chain reaction. Preparation time may be shortened by substituting a high‐salt precipitation procedure for the dialysis step; however, this results in a smaller average fragment size. The isolation of DNA from buccal swabs, collected from the inside of the cheek, is also described. The DNA is suitable for PCR analysis. Preparation of buffered phenol for DNA extraction is described in a support protocol.This unit describes simple, cost‐effective preparation of DNA from whole blood or cultured cells that yields high‐molecular‐we
Denaturing Polyacrylamide Gel Electrophoresis
Authors: Albright Lisa M. , Slatko Barton E.
Published: June 2004

Polyacrylamide gels that contain a high concentration of urea as a denaturant are capable of resolving short (<500 nucleotides) single‐stranded fragments of DNA or RNA that differ in length by as little as one nucleotide. Such gels are commonly used for DNA sequence analysis, as well as in PCR amplification of SSLPs (simple sequence length polymorphisms) for genotyping, genotyping by the ligase chain reaction (LCR), analysis of mutations by RNase A cleavage, chemical cleavage of heteroduplex DNA to identify mutations, and molecular analysis of fragile X syndrome by PCR. This appendix presents a protocol for the pouring, running, and processing of a typical gel which is 40‐cm long with a uniform thickness of 0.4 mm, containing 7 M urea and 4% to 8% acrylamide.
ISCN Standard Idiograms
Authors: Schreck Rhona R. , Distèche Christine M. , Adler David
Published: June 2004

Chromosome banding is used mainly to identify both normal and rearranged chromosomes, to define chromosome breakpoints, and to describe the specific location of DNA sequences on chromosomes. A nomenclature has been developed to standardize the identification of chromosomes and the naming of chromosome bands. The system currently in use is An International System for Human Cytogenetic Nomenclature, referred to as “ISCN 1995.” It is the report of the standing committee on human cytogenetic nomenclature edited by Felix Mitelman. The report includes a chromosome band nomenclature, as well as standard idiograms, which are “diagrammatic representations of a karyotype, which may be based on measurements of the chromosomes” (ISCN 1995). The idiograms presented here, with the permission of S. Karger and Cytogenetics and Cell Genetics, are drawings of G‐banded chromosomes with band numbers indicated. Heterochromatic regions, which contain classes of repetitive DNA and can show individual differences in size, are indicated by patterned areas.
Enzymatic Kinetic Resolution of 1,3‐Dioxolan‐4‐one and 1,3‐Oxathiolan‐5‐one Derivatives: Synthesis of the Key Intermediate in the Industrial Synthesis of the Nucleoside Reverse Transcriptase Inhibitor AMDOXOVIR
Authors: Popp Alfred , Gilch Andrea , Mersier Anne‐Laure , Petersen Hermann , Rockinger‐Mechlem Jodoca , Stohrer Jürgen
Published: June 2004

The resolution of racemic 1,3‐dioxolan‐4‐one and 1,3‐oxathiolan‐5‐one derivatives such as (4‐oxo‐1,3‐dioxolan‐2‐yl)methyl 2‐methylpropanoate (2) by enzymatic solvolysis was investigated. The resolution of 2, a precursor for the synthesis of the nucleoside reverse transcriptase inhibitor Amdoxovir, was optimized in terms of solvent/nucleophile, reaction conditions, and enzyme. The use of lipase from Candida antarctica B (CALB) and methanol as nucleophile and solvent resulted in an effective resolution and the product (R)‐2 could be easily isolated. Products of substrate decomposition can be isolated and reused for the synthesis of racemic 2. The broad range of application for this enzymatic resolution was demonstrated by the resolution of further substrates with different substitution patterns. This process gives a new and unprecedented access to enantiopure 1,3‐dioxolan‐4‐ones and 1,3‐oxathiolan‐5‐ones.
Photooxidation in Water by New Hybrid Molecular Photocatalysts Integrating an Organic Sensitizer with a Polyoxometalate Core
Authors: Bonchio Marcella , Carraro Mauro , Scorrano Gianfranco , Bagno Alessandro
Published: June 2004

Hybrid compounds consisting of an organic sensitizer and a polyoxometalate unit were synthesized following two strategies: a) the covalent functionalization of lacunary decatungstosilicate with organosilylfulleropyrrolidines; b) the charge interaction between cationic sensitizers and the polyoxoanions, yielding electrostatic aggregates. These hybrid complexes effect catalytic photooxygenation in water under heterogeneous conditions, 25 °C and O2 (1 atm), using visible light irradiation (λ>375 nm). As representative target substrates, phenol (4 mM) is oxidized in 150 min with a COD loss up to 30% (TON up to 50), while L‐methionine methyl ester (15 mM) undergoes selective photooxygenation to the corresponding sulfoxide in 90 min (TON up to 200). The photocatalyst stability has been evaluated on the basis of system recycling along three oxidation runs. The inhibition exerted by sodium azide, a typical 1O2 quencher, suggests the occurrence of a Type II photooxidation mechanism.
Trichloroisocyanuric Acid: A Convenient Oxidation Reagent for Phase‐Transfer Catalytic Epoxidation of Enones under Non‐Aqueous Conditions
Authors: Ye Jinxing , Wang Yongcan , Chen Jiping , Liang Xinmiao
Published: June 2004

Trichloroisocyanuric acid (TCCA) is a cheap, safe and readily available alternative to the commonly used hydrogen peroxide and hypochlorite for the phase‐transfer catalytic epoxidation of α,β‐enones under non‐aqueous conditions. A variety of chalcone derivatives give the corresponding epoxides with quantitative conversion and satisfactory yields in just a few hours under mild conditions. An asymmetric variant of the epoxidation can be carried out in the presence of chiral N‐anthracenylmethylcinchonidine bromide catalyst giving 73–93% ees and 76–94% yields.
Hydrogenation of Nitrobenzene with Supported Transition Metal Catalysts in Supercritical Carbon Dioxide
Authors: Zhao Fengyu , Zhang Rong , Chatterjee Maya , Ikushima Yutaka , Arai Masahiko
Published: June 2004

Transition metal catalysts such as Pd, Pt, Ru, and Rh supported on carbon, silica and alumina have been examined for the hydrogenation of nitrobenzene (NB) in supercritical carbon dioxide (scCO2) and in ethanol. The order of hydrogenation activity is Pt>Pd>Ru, Rh in scCO2 and in ethanol. The effectiveness of the support is C>Al2O3, SiO2 for either Pt or Pd in scCO2. For all the catalysts, higher selectivity to aniline has been obtained in scCO2 compared with ethanol. Hydrogenation of nitrobenzene catalyzed with Pd/C and Pt/C catalysts was successfully conducted in scCO2 with a 100% yield to aniline at a lower reaction temperature of 35 °C. The product aniline (organic phase) can be easily separated from the side‐product water (aqueous phase), solvent (scCO2), and catalyst (solid) by a simple phase separation process. The hydrogenation of NB is a structure‐sensitive reaction in ethanol as well as in scCO2 except for a few Pt/C catalysts in which the degree of metal dispersion is small (<0.08).
Application of SDP Ligands for Pd‐Catalyzed Allylic Alkylation
Authors: Xie Jian‐Hua , Duan Hai‐Feng , Fan Bao‐Min , Cheng Xu , Wang Li‐Xin , Zhou Qi‐Lin
Published: June 2004

Chiral spiro diphosphines (SDP) are efficient ligands for the Pd‐catalyzed asymmetric allylic alkylation of 1,3‐diphenyl‐2‐propenyl acetate with dimethyl malonate and related nucleophiles. The newly synthesized ligand DMM‐SDP (1e) with 3,5‐dimethyl‐4‐methoxy groups on the P‐phenyl rings of the phosphine shows the highest enantioselectivity (up to 99.1% ee). Diethylzinc as a base is critical for obtaining high enantioselectivity in the allylic alkylation using β‐dicarbonyl nucleophiles. The structure of catalyst [PdCl2((S)‐SDP)] was determined by single crystal X‐ray diffraction. The SDP ligands create an effective asymmetric environment around the palladium, resulting in high enantioselectivities for the asymmetric allylic alkylation reaction
Oxidative dehydrogenation of butane in an interconnected fluidized‐bed reactor
Authors: Rubio O. , Herguido J. , Menéndez M. , Grasa G. , Abanades J. C.
Published: June 2004

The use of an internal circulating fluidized bed (ICFB) is proposed for the oxidative dehydrogenation of butane. The reactor consists of two adjacent zones, separated by a wall. In the oxidizing zone the catalyst is oxidized and in the reducing zone the butane is dehydrogenated by reaction with the oxygen from the catalyst lattice. The circulation between both zones is produced by the different bed porosity, which originates a pressure difference between the two zones at the communication orifice at the bottom of the vessel. The design of this reactor is studied in a cold model. An image analysis technique was applied to measure solid circulation rates between the different regions in the reactor, by using a solid coated with a long afterglow phosphor as a tracer. The solid circulation rates through the orifices were found to correlate reasonably well with a previously developed correlation for the orifice drag coefficient. The model for solid circulation between fluidized regions was then integrated in the overall mathematical model for the ICFB reactor system to incorporate the effect of design and operating conditions on the catalyst circulation rates between compartments. A good correlation between the experimentally obtained values of conversion and selectivity and those predicted by the model is obtained. Improvements in selectivity to olefins are obtained, compared with conventional fluidized‐bed reactors with cofeeding of reactants. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1510–1522, 2004
Plantwide control for TAME production using reactive distillation
Authors: Al‐Arfaj Muhammad A. , Luyben William L.
Published: June 2004

The synthesis and control of a plantwide flowsheet to produce tert‐amyl methyl ether (TAME) is reported. The flowsheet consists of a plug‐flow reactor, one reactive distillation column, and two conventional distillation columns. The two conventional columns are needed for the recovery of excess methanol and the inert C5s. The columns are operated at different pressures to overcome separation limitations resulting from the presence of azeotropes. The reactive distillation is run with an excess of methanol because it is needed for both the reaction and the azeotropic vapor liquid equilibrium (VLE) requirements in the column. The reactive distillation column is the critical unit in this flowsheet that needs to be carefully controlled. An effective control structure is one in which a temperature in the stripping section and a methanol composition in the reactive zone are controlled. This control scheme is similar to that applied to other reactive distillation systems of the same type (that is, ETBE, MTBE). Because there is no reaction in the other two columns, they are effectively controlled by simple temperature controllers. The fresh feed of methanol must be manipulated to maintain the overall balance of methanol in the flowsheet. The proposed control structure is able to handle disturbances in feed rate and composition up to ±20%.© 2004 American Institute of Chemical Engineers AIChE J, 50: 1462–1473, 2004
Feasible products in batch reactive extractive distillation
Authors: Guo Zhe , Lee Jae W.
Published: June 2004

A systematic feasibility evaluation method is presented for batch reactive distillation columns with extractive feed streams. In this batch configuration, one feasibility criterion is obtained for quaternary reactive systems by using residue curve maps and reaction equilibrium manifolds. If all reaction products are saddles and one of the binary azeotropes between the desired products and the other components is an unstable node, then a reactive rectifier with a side‐feed entrainer can produce pure products regardless of the type and number of azeotropes involved in the system. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1484–1492, 2004
Energetic costs of bipedal and quadrupedal walking in Japanese macaques
Authors: Nakatsukasa M. , Ogihara N. , Hamada Y. , Goto Y. , Yamada M. , Hirakawa T. , Hirasaki E.
Published: June 2004

We investigated the energetic costs of quadrupedal and bipedal walking in two Japanese macaques. The subjects were engaged in traditional bipedal performance for years, and are extremely adept bipeds. The experiment was conducted in an airtight chamber with a gas analyzer. The subjects walked quadrupedally and bipedally at fixed velocities (<5 km/hr) on a treadmill in the chamber for 2.5–6 min. We estimated energy consumption from carbon dioxide (CO2) production. While walking bipedally, energetic expenditure increased by 30% relative to quadrupedalism in one subject, and by 20% in another younger subject. Energetic costs increased linearly with velocity in quadrupedalism and bipedalism, with bipedal/quadrupedal ratios remaining almost constant. Our experiments were relatively short in duration, and thus the observed locomotor costs may include presteady‐state high values. However, there was no difference in experimental duration between bipedal and quadrupedal trials. Thus, the issue of steady state cannot cancel the difference in energetic costs. Furthermore, we observed that switching of locomotor mode (quadrupedalism to bipedalism) during a session resulted in a significant increase of CO2 production. Taylor and Rowntree ([ 1973] Science 179:186–187) noted that the energetic costs for bipedal and quadrupedal walking were the same in chimpanzees and capuchin monkeys. Although the reason for this inconsistency is not clear, species‐specific differences should be considered regarding bipedal locomotor energetics among nonhuman primates. Extra costs for bipedalism may not be great in these macaques. Indeed, it is known that suspensory locomotion in Ateles consumes 1.3–1.4 times as much energy relative to quadrupedal progression. This excess ratio surpasses the bipedal/quadrupedal energetic ratios in these macaques. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Genetics and the evolution of primate enamel thickness: A baboon model
Authors: Hlusko Leslea J. , Suwa Gen , Kono Reiko T. , Mahaney Michael C.
Published: June 2004

The thickness of mammalian tooth enamel plays a prominent role in paleontology because it correlates with diet, and thicker enamel protects against tooth breakage and wear. Hominid evolutionary studies have stressed the importance of this character for over 30 years, from the identification of “Ramapithecus” as an early Miocene hominid, to the recent discovery that the earliest hominids display molar enamel intermediate in thickness between extant chimpanzees and Australopithecus. Enamel thickness remains largely unexplored for nonhominoid primate fossils, though there is significant variation across modern species. Despite the importance of enamel thickness variation to primate evolution, the mechanisms underlying variation in this trait have not yet been elucidated. We report here on the first quantitative genetic analysis of primate enamel thickness, an analysis based on 506 pedigreed baboons from a captive breeding colony. Computed tomography analysis of 44 Papio mandibular molars shows a zone of sufficiently uniform enamel thickness on the lateral surface of the protoconid. With this knowledge, we developed a caliper metric measurement protocol for use on baboon molars worn to within this zone, enabling the collection of a data set large enough for genetic analyses. Quantitative genetic analyses show that a significant portion of the phenotypic variance in enamel thickness is due to the additive effects of genes and is independent of sex and tooth size. Our models predict that enamel thickness could rapidly track dietary adaptive shifts through geological time, thus increasing the potential for homoplasy in this character. These results have implications for analyses of hominoid enamel thickness variation, and provide a foundation from which to explore the evolution of this phenotype in the papionin fossil record. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Horse‐mounted invaders from the Russo‐Kazakh steppe or agricultural colonists from western Central Asia? A craniometric investigation of the Bronze Age settlement of Xinjiang
Authors: Hemphill Brian E. , Mallory J.P.
Published: June 2004

Numerous Bronze Age cemeteries in the oases surrounding the Täklamakan Desert of the Tarim Basin in the Xinjiang Uyghur Autonomous Region, western China, have yielded both mummified and skeletal human remains. A dearth of local antecedents, coupled with woolen textiles and the apparent Western physical appearance of the population, raised questions as to where these people came from. Two hypotheses have been offered by archaeologists to account for the origins of Bronze Age populations of the Tarim Basin. These are the “steppe hypothesis” and the “Bactrian oasis hypothesis.” Eight craniometric variables from 25 Aeneolithic and Bronze Age samples, comprising 1,353 adults from the Tarim Basin, the Russo‐Kazakh steppe, southern China, Central Asia, Iran, and the Indus Valley, are compared to test which, if either, of these hypotheses are supported by the pattern of phenetic affinities possessed by Bronze Age inhabitants of the Tarim Basin. Craniometric differences between samples are compared with Mahalanobis generalized distance (d2), and patterns of phenetic affinity are assessed with two types of cluster analysis (the weighted pair average linkage method and the neighbor‐joining method), multidimensional scaling, and principal coordinates analysis. Results obtained by this analysis provide little support for either the steppe hypothesis or the Bactrian oasis hypothesis. Rather, the pattern of phenetic affinities manifested by Bronze Age inhabitants of the Tarim Basin suggests the presence of a population of unknown origin within the Tarim Basin during the early Bronze Age. After 1200 B.C., this population experienced significant gene flow from highland populations of the Pamirs and Ferghana Valley. These highland populations may include those who later became known as the Saka and who may have served as “middlemen” facilitating contacts between East (Tarim Basin, China) and West (Bactria, Uzbekistan) along what later became known as the Great Silk Road. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Metallionen‐Gitterarchitekturen: funktionelle supramolekulare Metallkomplexe
Authors: Ruben Mario , Rojo Javier , Romero‐Salguero Francisco J. , Uppadine Lindsay H. , Lehn Jean‐Marie
Published: June 2004

Jüngste 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

Recent 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

Heparin 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

The 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

Dual‐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

The 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

This 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

The 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

Das 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

The 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

Der 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

Der 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

Die 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

Proline‐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

Nd2‐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

We 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

Kidney 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

Nano 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

It 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

The 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

The 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

Deuterium 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)
Scanning fluorescent microscopy is an alternative for quantitative fluorescent cell analysis
Authors: Varga Viktor Sebestyén , Bocsi József , Sipos Ferenc , Csendes Gábor , Tulassay Zsolt , Molnár Béla
Published: June 2004

Background

Fluorescent measurements on cells are performed today with FCM and laser scanning cytometry. The scientific community dealing with quantitative cell analysis would benefit from the development of a new digital multichannel and virtual microscopy based scanning fluorescent microscopy technology and from its evaluation on routine standardized fluorescent beads and clinical specimens.

Methods

We applied a commercial motorized fluorescent microscope system. The scanning was done at 20× (0.5 NA) magnification, on three channels (Rhodamine, FITC, Hoechst). The SFM (scanning fluorescent microscopy) software included the following features: scanning area, exposure time, and channel definition, autofocused scanning, densitometric and morphometric cellular feature determination, gating on scatterplots and frequency histograms, and preparation of galleries of the gated cells. For the calibration and standardization Immuno‐Brite beads were used.

Results

With application of shading compensation, the CV of fluorescence of the beads decreased from 24.3% to 3.9%. Standard JPEG image compression until 1:150 resulted in no significant change. The change of focus influenced the CV significantly only after ±5 μm error.

Conclusions

SFM is a valuable method for the evaluation of fluorescently labeled cells. © 2004 Wiley‐Liss, Inc.
Scalable resource management for high‐performance Web servers
Authors: Hasegawa Go , Terai Tatsuhiko , Okamoto Takuya , Murata Masayuki
Published: June 2004

Although many research efforts have been devoted to network congestion in the face of an increase in the Internet traffic, there is little recent discussion on performance improvements for endhosts. In this paper, we propose a new architecture, called scalable socket buffer tuning (SSBT), to provide high‐performance and fair service for many TCP connections at Internet endhosts. SSBT has two major features. One is to reduce the number of memory accesses at the sender host by using some new system calls, called Simple Memory‐copy Reduction (SMR) scheme. The other is equation‐based automatic TCP buffer tuning (E‐ATBT), where the sender host estimates ‘expected’ throughput of the TCP connections through a simple mathematical equation, and assigns a send socket buffer to them according to the estimated throughput. If the socket buffer is short, max–min fairness policy is used. We confirm the effectiveness of our proposed algorithm through both simulation technique and an experimental system. From the experimental results, we have found that our SSBT can achieve up to a 30% gain for Web server throughput, and a fair and effective usage of the sender socket buffer can be achieved. Copyright © 2004 John Wiley & Sons, Ltd.
The distribution of file transmission duration in the web
Authors: Nossenson R. , Attiya H.
Published: June 2004

It is well known that the distribution of files transmission duration in the Web isheavy‐tailed(A practical guide to Heavy Tails: Statistical Techniques and Application. Birkhauser: Boston, 1998; 3–26). This paper attempts to understand the reasons for this phenomenon by isolating the three major factors influencing the transmission duration: file size, network conditions and server load.

We present evidence that the transmission‐duration distribution (TDD) of thesamefile from the same server to the same client in the Web is Pareto and therefore heavy tailed. Furthermore, text files transmission delay for a specific client/server pair is not significantly affected by the file sizes: all files transmitted from the same server to the same client have very similar transmission duration distributions, regardless of their size.

We use simulations to estimate the impact of network conditions and server load on the TDD. When the server and the client are on the same local network, the TDD of each file is usually Pareto as well (for server files and client requests that are distributed in a realistic way).

By examining a wide‐area network situation, we conclude that the network conditions do not have a major influence on the heavy‐tailed behaviour of TDD. In contrast, the server load is shown to have a significant impact on the high variability of this distribution. Copyright © 2004 John Wiley & Sons, Ltd.
Wireless video streaming with TCP and simultaneous MAC packet transmission (SMPT)
Authors: Fitzek Frank H. P. , Reisslein Martin
Published: June 2004

Video streaming is expected to account for a large portion of the traffic in future networks, including wireless networks. It is widely accepted that the user datagram protocol (UDP) is the preferred transport protocol for video streaming and that the transmission control protocol (TCP) is unsuitable for streaming. The widespread use of UDP, however, has a number of drawbacks, such as unfairness and possible congestion collapse, which are avoided by TCP. In this paper we investigate the use of TCP as the transport layer protocol for streaming video in a multi‐code CDMA cellular wireless system. Our approach is to stabilize the TCP throughput over the wireless links by employing a recently developed simultaneous MAC packet transmission (SMPT) approach at the link layer. We study the capacity, i.e. the number of customers per cell, and the quality of service for streaming video in the uplink direction. Our extensive simulations indicate that streaming over TCP in conjunction with SMPT gives good performance for video encoded in a closed loop, i.e. with rate control. We have also found that TCP is unsuitable (even in conjunction with SMPT) for streaming the more variable open‐loop encoded video. Copyright © 2004 John Wiley & Sons, Ltd.