bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Bi4Mn1/3W2/3O8Cl Sillén–Aurivillius Intergrowth: Synthesis and Structural Characterisation by Quantitative Transmission Electron Microscopy
Authors: Ávila‐Brande David , Otero‐Díaz L. Carlos , Landa‐Cánovas Ángel R. , Bals Sara , Van Tendeloo Gustaaf 
Published: March 2006

AbstractThe synthesis and structural characterisation of a new phase with nominal composition Bi4Mn1/3W2/3O8Cl is presented. Conventional and analytical transmission electron microscopy are used to determine the composition, unit‐cell symmetry and space group of the compound, whereas a structural model is deducted by exit‐wave reconstruction in the transmission electron microscope. This technique allows the microscope information limit of 1.1 Å to be reached and the (light) oxygen atoms in the presence of heavier atoms (Bi, W, Mn) to be imaged. The average structure is refined from X‐ray powder diffraction data using the Rietveld method yielding an orthorhombic unit cell with lattice parameters a = 5.467(4) Å, b = 5.466(7) Å and c = 14.159(3) Å and space group Cm2m, which could be described as a Sillén–Aurivillius intergrowth. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis of New Water‐Soluble DNA‐Binding Subunits for Analogues of the Cytotoxic Antibiotic CC‐1065 and Their Prodrugs
Authors: Tietze Lutz F. , Major Felix 
Published: March 2006

AbstractNovel water‐soluble indole‐2‐carboxylic acid derivatives (7, 13, 21 and 25) bearing a substituent with a tertiary amino functionality at C‐5 have been prepared. These new DNA‐binding subunits can be used for the synthesis of new analogues of the cytotoxic antibiotic CC‐1065 and their corresponding prodrugs for antibody‐directed enzyme prodrug therapy (ADEPT) within a selective treatment of cancer.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Selective Inclusion of Equatorial Isomers of Cyclohexane‐Polyols in Phosphonium Salt Hosts
Authors: Tanaka Koichi , Nakashima Aki , Shimada Yuji , Scott Janet L. 
Published: March 2006

AbstractPhosphonium salt host compounds 1–3 form inclusion crystals with cyclohexane‐1,3‐diol (4), cyclohexane‐1,4‐diol (5) and cyclohexane‐1,3,5‐triol (6), in which the equatorial conformers are selectively included. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Conjugated Azomethine Ylides
Authors: Pinho e Melo Teresa M. V. D. 
Published: March 2006

AbstractThe 1,3‐dipolar cycloaddition of azomethine ylides is an efficient and versatile tool for the construction of five‐membered nitrogen‐heterocycles. When the azomethine ylide is conjugated with a double bond or a 1,3‐diene moiety, other reactivity pathways are also available, namely 1,5‐electrocyclization or 1,7‐electrocyclization. The present review is focused on the generation and reactivity of this type of dipoles, which offer general strategies for the formation of five‐ and seven‐membered nitrogen‐heterocyclic compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
The Suzuki Coupling of Aryl Chlorides in Aqueous Media Catalyzed by in situ Generated Calix[4]arene‐Based N‐Heterocyclic Carbene Ligands
Authors: Brendgen Thomas , Frank Markus , Schatz Jürgen 
Published: March 2006

AbstractWe report on the use of an in situ system for the catalytic Suzuki cross‐coupling reaction of chlorobenzenes and benzeneboronic acid to yield biphenyls. Calix[4]arene‐based imidazolium salts were used as precursors of N‐heterocyclic carbene ligands and Pd(OAc)2as the palladium source. In dioxane as the organic medium, the steric demands of the substituents on the calixarene skeleton and on the imidazolium moiety parallel the catalytic activity; the best catalytic results were obtained by using dimesityl‐ or 2,6‐diisopropylphenyl‐substituted calixarene‐imidazolium salts. Among the bases tested Cs2CO3and CsF were the most effective. The catalytic protocol established for organic solvents could also be used for the Suzuki cross‐coupling reaction in aqueous solution. In dioxane/water (50:50) the activity is nearly the same as in pure dioxane and in pure water, an environmentally friendly and cheap solvent, a 60 % level of reactivity was maintained; here the calixarene ligand precursor3ashowed the highest activity. Nonmacrocyclic compounds used for comparison showed considerably lower catalytic ability proving that calix[4]arene‐based imidazolium salts are attractive supramolecular skeletons for the N‐heterocyclic carbene ligands used in selective Suzuki cross‐coupling reactions of aryl chlorides in aqueous solution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Validated capillary electrophoresis assay for the simultaneous enantioselective determination of propafenone and its major metabolites in biological samples
Authors: Afshar Minoo , Thormann Wolfgang 
Published: March 2006

AbstractA robust, inexpensive, and fully validated CE method for the simultaneous determination of the enantiomers of propafenone (PPF), 5‐hydroxy‐propafenone (5OH‐PPF) and N‐despropyl‐propafenone (NOR‐PPF) in serum and in in vitro media is described. It is based upon liquid–liquid extraction at alkaline pH followed by analysis of the reconstituted extract by CE in presence of a pH 2.0 running buffer composed of 100 mM sodium phosphate, 19% methanol, and 0.6% highly sulfated β‐CD. For each compound, the S‐enantiomers are shown to migrate ahead of their antipodes, and the overall run time is about 30 min. Enantiomer levels between 25 and 1000 ng/mL provide linear calibration graphs, and the LOD for all enantiomers is between 10 and 12 ng/mL. The assay is shown to be suitable for the determination of the enantiomers of PPF and its metabolites in in vitro incubations comprising human liver microsomes or single CYP450 enzymes (SUPERSOMES). Incubations with CYP2D6 SUPERSOMES revealed, for the first time, the simultaneous formation of the enantiomers of 5OH‐PPF and NOR‐PPF with that enzyme. CE data can be used for the evaluation of the enzymatic N‐dealkylation and hydroxylation rates.
Selenium‐binding protein 2, the major hepatic target for acetaminophen, shows sex differences in protein abundance
Authors: Mattow Jens , Demuth Ilja , Haeselbarth Gisela , Jungblut Peter R. , Klose Joachim 
Published: March 2006

AbstractLiver samples from female and male mice of two subspecies, Mus musculus musculus and Mus musculus domesticus, were investigated by a combination of 2‐DE and MALDI‐MS. The image analysis of the generated 2‐DE patterns revealed several protein spots with significant differences in intensity/abundance between the sexes. Seven protein spots, which were prominent in 2‐DE patterns of male mice, but which showed very low intensities in females, were identified as selenium‐binding protein 2 (SBP2) also known as 56‐kDa acetaminophen‐binding protein. Edman degradation indicated that at least three of these protein spots represent N‐terminally truncated SBP2 variants. Furthermore, it was shown that the observed differences in SBP2 abundance correlate with sex differences in transcription of the gene encoding SBP2, selenbp2, as revealed by RT‐PCR and restriction digest as well as sequence analysis of the products. Since SBP2 has been described as the major target for acetaminophen in mouse liver cytosol, these findings are discussed with respect to their possible relevance for sex differences in acetaminophen‐mediated toxicity, which have been described in a variety of mammals including mice and rats.
Selection of surfactants for cell lysis in chemical cytometry to study protein‐DNA interactions
Authors: Pang Zhulin , Al‐Mahrouki Azza , Berezovski Maxim , Krylov Sergey N. 
Published: March 2006

AbstractProtein‐DNA interactions play a defining role in many cellular processes. Studying such interactions at the single‐cell level is important and challenging. Here we make the first step toward achieving this goal with chemical cytometry. Chemical cytometry utilizes capillary separation for detailed chemical analyses of single cells. The cell is injected into a capillary, lysed, and its components are analyzed by CE or capillary chromatography with highly sensitive detection. In order to apply chemical cytometry to studies of protein‐DNA interactions, cell lysis must not destroy protein‐DNA complexes. Surfactants represent the most practical means of cell lysis inside the capillary. This work aimed at finding surfactants and lysis conditions that do not destroy protein‐DNA complexes. We studied three groups of surfactants – ionic, zwitterionic, and nonionic – with respect to their ability to lyse the cell membrane without significantly influencing the stability of protein‐DNA complexes. Nonequilibrium CE of equilibrium mixtures with surfactants in the equilibrium mixtures and in the run buffer was used to measure the equilibrium constant, Kd, and rate constant, koff, of protein‐DNA complex dissociation. We found that nonionic surfactants worked best: they lyse the plasma membrane without significantly influencing Kd, koff, or the EOF. This work creates the foundation for studies of protein‐DNA interactions in single cells by chemical cytometry.
Contribution of cell culture additives to the two‐dimensional protein patterns of mouse macrophages
Authors: Miller Ingrid , Radwan Marta , Strobl Birgit , Müller Mathias , Gemeiner Manfred 
Published: March 2006

AbstractLow levels of fetal calf serum (FCS), used as protein supplement in cell culture medium, were traced in preparations of primary murine macrophages (bone‐marrow‐derived macrophages (BMM) and peritoneal macrophages (PM)). Main components of this common additive were mapped in 2‐DE by means of differential image gel electrophoresis and immunoblotting. Additional washing steps in cell preparation helped to decrease the levels of the four highest abundance foetal serum proteins (serum albumin (SA), α1‐fetoprotein (AFP), α1‐antitrypsin (α1AT) and transferrin (Tf)) to less than 1% of total protein. Macrophage spot pattern was recorded in parallel and showed little variation. Results presented are supposed to be of general interest for cell preparations with similar background.
Rapid quantification of human complement component C4A and C4B genes by capillary gel electrophoresis
Authors: Szilagyi Agnes , Blasko Bernadett , Ronai Zsolt , Fust Gyorgy , Sasvari‐Szekely Maria , Guttman András 
Published: March 2006

AbstractComplement component 4 (C4) is an important plasma protein playing a major role in the human defense mechanism against infectious diseases and inflammatory processes. The C4A and C4B genes, encoding the two isoforms of complement 4, are located in the nuclear serine/threonine protein kinase‐C4A or B gene‐cytochrome 21‐hydroxylase‐tenascin X module (RP‐C4‐CYP21‐TNX) and manifested by variable copy numbers among individuals between zero to six in the human diploid genome. Quantification of the C4A and C4B genes has great clinical importance since unbalanced production of C4A and C4B proteins might be associated with pathological immune processes. Albeit, high‐throughput analysis methods for C4 gene dosage determination are not yet available. Here we present a novel combination of allele‐specific PCR and CGE separation for rapid quantification of the C4A and C4B genes where a single‐step, single‐tube PCR reaction generates two allele‐specific (C4A and C4B) and two control amplicons, followed by CGE analysis of the four fragments. The method presented in this paper enables automated and high‐throughput gene dosage analysis of large sample cohorts.
Enhanced method performances for conventional and chiral CE‐ESI/MS analyses in plasma
Authors: Schappler Julie , Guillarme Davy , Prat Josiane , Veuthey Jean‐Luc , Rudaz Serge 
Published: March 2006

AbstractDue to its high efficiency, selectivity, and sensitivity, CE‐ESI/MS has evolved as an efficient technique for the drugs and metabolites analysis in biological matrices. However, a sample preparation is mandatory prior to CE‐ESI/MS analysis. To achieve fast and simplified sample preparation of plasma samples, protein precipitation (PP) and liquid–liquid extraction (LLE) were used with two injection techniques: hydrodynamic (HD) and electrokinetic (EK) injection. CE‐ESI/MS analyses of pharmaceutical compounds and amphetamine derivatives were developed. Detection limits of 1 ppm were reached with PP and HD injection whereas 1 ppb was detected when samples were prepared with LLE and injected by EK. Same experiments were performed for stereoselective determinations in partial‐filling mode and detection limits achieved were equivalent to conventional analysis (0.5 ppb per enantiomer). When complex matrices are analyzed, MS signal suppression or enhancement effects are generally not reproducible and could compromise results with ESI. Therefore, matrix effect was investigated in CE‐ESI/MS with a commercially available coaxial sheath–liquid ESI interface used as postcapillary infusion system to determine MS signal alterations. Matrix effects were differentially evidenced according to the selected sample preparation. With PP, signal suppression was observed out of the analyses migration window, while for LLE no relevant matrix effect occurred in all experiments.
Model study of the relationship between sediment yield and river basin area
Authors: Birkinshaw S. J. , Bathurst J. C. 
Published: March 2006

AbstractThe SHETRAN physically based, spatially distributed model is used to investigate the scaling relationship linking specific sediment yield to river basin area, for two contrasting topographies of upland and more homogeneous terrain and as a function of sediment source, land use and rainfall distribution. Modelling enables the effects of the controls to be examined on a systematic basis, while avoiding the difficulties associated with the use of field data (which include limited data, lack of measurements for nested basins and inability to isolate the effects of individual controls). Conventionally sediment yield is held to decrease as basin area increases, as the river network becomes more remote from the headwater sediment sources (an inverse relationship). However, recent studies have reported the opposite variation, depending on the river basin characteristics. The simulation results are consistent with these studies. If the sediment is supplied solely from hillslope erosion (no channel bank erosion) then, with uniform land use, sediment yield either decreases or is constant as area increases. The downstream decrease is accentuated if rainfall (and thence erosion) is higher in the headwaters than at lower elevations. Introducing a non‐uniform land use (e.g. forest at higher elevations, wheat at lower elevations) can reverse the trend, so that sediment yield increases downstream. If the sediment is supplied solely from bank erosion (no hillslope erosion), the sediment yield increases downstream for all conditions. The sediment yield/basin area relationship can thus be inverse or direct, depending on basin characteristics. There still remains, therefore, considerable scope for defining a universal scaling law for sediment yield. Copyright © 2006 John Wiley & Sons, Ltd.
Coeval biochemical and biophysical weathering processes on Quaternary sandstone terraces south of Rabat (Temara), northwest Morocco
Authors: Duane Michael J. 
Published: March 2006

AbstractDespite numerous investigations on substrate‐inhabiting microflora, especially lichens, very little is known about the colonization of coastal escarpments by lithobiontic micro‐organisms, inland of a retreating coastline in Africa. Reported herein are the results of a combined field observation and microscopy study focusing on the connection between microrelief of the substrate, colonies of lithobiontic micro‐organisms (in particular the lichen Xanthoria parietina) and microstructures of putative bacterial origin. The occurrence of weathering pits in which the early stages of the biotic development occurs, and the subsequent disintegration of the rock indicate that lichens, mosses and fungi act synergistically by alternating chemical and mechanical weathering. Penetration of grains by expansion and contraction of the hyphae depletes the rock matrix and contributes to the mechanical breakdown of the rock. Calcite rhombs on the weathered surfaces of the calcite‐cemented sandstones are severely etched with well‐developed rhomb‐shaped etch pits (‘spiky calcite’), holes, or has one or more of the faces removed, and their cores exposed and leached. Nanofilaments (c. 100–700 nm) and ‘nanomicrobial’ fruiting bodies (c. 250 nm) emanating from micropores appear to be common on affected crystalline structures. Weddellite present immediately below the thallus is a strong indicator of biomineralization.Quartz responds differently to chemical weathering by producing peeling structures and microbrecciation features. The dissolution of these crystals appears to be a surface reaction‐controlled process mediated by microbial microfilaments and nanofilaments. A model is proposed, firstly indicating early‐stage biochemical weathering, followed by biophysical weathering. Disintegration of the rock outcrops in due to a complex interplay of several events, probably beginning at the nanoscale with penetration of sites on crystal faces. Copyright © 2006 John Wiley & Sons, Ltd.
A mass movement origin for cirques
Authors: Turnbull Jill M. , Davies Timothy R. H. 
Published: March 2006

AbstractThe glacial process of cirque initiation, whereby small initial hillslope hollows grow by nivation until snow can form glacier ice, and ice motion then enlarges the hollow to a fully developed cirque, appears to have difficulty explaining the creation of large cirques in the time available during Quaternary glaciations, at the rates at which glaciers are reported to erode rock, and in rapidly uplifting mountain ranges. It also has difficulty explaining the striking proliferation of cirques in Fiordland, South Island, New Zealand, an area of harder rock and less glaciation than the nearby cirque‐poor area of South Westland. Here we show that cirques can be initiated as large, deep‐seated, often coseismic rock slope failure source area depressions in which snow may accumulate to form cirque glaciers, which can then remove detritus from, smooth, and enlarge the cirque. We present an example of a classically shaped cirque that has never held a glacier. We show that many similarities between the locations, sizes and shapes of rock slope failure source area depressions and cirques are understandable on this basis, as is the occurrence of cirques in presently aseismic intraplate locations and their relative paucity in actively uplifting ranges. The extent to which cirques may be of mass movement origin has implications for their value as palaeoclimatic indicators. Copyright © 2006 John Wiley & Sons, Ltd.
The multi‐stage centred‐scheme approach applied to a drift‐flux two‐phase flow model
Authors: Munkejord Svend Tollak , Evje Steinar , Flåtten Tore 
Published: March 2006

AbstractFor two‐phase flow models, upwind schemes are most often difficult do derive, and expensive to use. Centred schemes, on the other hand, are simple, but more dissipative. The recently proposed multi‐stage (MUSTA) method is aimed at coming close to the accuracy of upwind schemes while retaining the simplicity of centred schemes. So far, the MUSTA approach has been shown to work well for the Euler equations of inviscid, compressible single‐phase flow. In this work, we explore the MUSTA scheme for a more complex system of equations: the drift‐flux model, which describes one‐dimensional two‐phase flow where the motions of the phases are strongly coupled. As the number of stages is increased, the results of the MUSTA scheme approach those of the Roe method. The good results of the MUSTA scheme are dependent on the use of a large‐enough local grid. Hence, the main benefit of the MUSTA scheme is its simplicity, rather than CPU‐time savings. Copyright © 2006 John Wiley & Sons, Ltd.
A compact finite difference method on staggered grid for Navier–Stokes flows
Authors: Zhang K. K. Q. , Shotorban B. , Minkowycz W. J. , Mashayek F. 
Published: March 2006

AbstractCompact finite difference methods feature high‐order accuracy with smaller stencils and easier application of boundary conditions, and have been employed as an alternative to spectral methods in direct numerical simulation and large eddy simulation of turbulence. The underpinning idea of the method is to cancel lower‐order errors by treating spatial Taylor expansions implicitly. Recently, some attention has been paid to conservative compact finite volume methods on staggered grid, but there is a concern about the order of accuracy after replacing cell surface integrals by average values calculated at centres of cell surfaces. Here we introduce a high‐order compact finite difference method on staggered grid, without taking integration by parts. The method is implemented and assessed for an incompressible shear‐driven cavity flow at Re = 103, a temporally periodic flow at Re = 104, and a spatially periodic flow at Re = 104. The results demonstrate the success of the method. Copyright © 2006 John Wiley & Sons, Ltd.
NG2 proteoglycan‐expressing microglia as multipotent neural progenitors in normal and pathologic brains
Authors: Yokoyama Akiko , Sakamoto Aiko , Kameda Kenji , Imai Yoshinori , Tanaka Junya 
Published: March 2006

AbstractRat primary microglia (MG) acquired a multipotent property to give rise to neuroectodermal cells through two‐step culture in 10 and 70% serum‐supplemented media for 5 days. Such multipotent MG, called promicroglioblasts (ProMGBs), formed cell aggregates, which generated cells with neuroectodermal phenotypes shortly after their transfer into serum‐free medium. As revealed by immunohistochemistry, there were a few MG expressing NG2 chondroitin sulfate proteoglycan (NG2) in the neonatal rat brain. Primary culture from the neonatal brain contained NG2+ MG, which appeared to be the source of NG2+ ProMGB aggregates. The aggregates were MG marker+/NG2+/GFAP+/NCAM+/S‐100β− and had alkaline phosphatase activity. The marked accumulation of NG2+ MG was observed close to stab wounds made in the mature rat brain. The accumulated NG2+ MG in the wound gradually decreased in number, but the cells persisted up to 150 days postlesioning. In addition, GFAP immunoreactivity increased markedly around the wound. The NG2+ MG in the wounds separated with trypsin‐EDTA formed NG2+ aggregates in 70% serum‐supplemented medium and then transformed into cells with neuroectodermal phenotypes in serum‐free medium. Although it is difficult to separate viable neurons from mature brains, cells from stab wounds generated process‐bearing β‐tubulin III+ cells in vitro easily. These data suggest that NG2+ MG in normal developing or pathologic brains are involved in the genesis or regeneration of the brain. © 2006 Wiley‐Liss, Inc.