bluuebunny/crossref_metadata_2025_split huggingface dataset:
O‐Acylated 2‐Phosphanylphenol Derivatives – Useful Ligands in the Nickel‐Catalyzed Polymerization of Ethylene
Authors: Yakhvarov Dmitry G. , Basvani Kaleswara R. , Kindermann Markus K. , Dobrynin Alexey B. , Litvinov Igor A. , Sinyashin Oleg G. , Jones Peter G. , Heinicke Joachim 
Published: February 2009

AbstractThe title ligands were prepared by O‐acylation of 2‐diphenylphosphanyl‐4‐methylphenol (1) or directly by double lithiation of 2‐bromo‐4‐methylphenol and stepwise coupling with ClPPh2 and ClP(O)Ph2 or RC(O)Cl (R = Me, tBu, Ph, 4‐MeOC6H4) to afford diphenylphosphinate 2 and carboxylic esters 3a–d. X‐ray crystal structure analyses of 3b–d show conformations in which the P‐phenyl substituents are rotated away from the ester group and the C(O)O π planes are nearly perpendicular to the phenol ring π plane. O‐Acylated phosphanylphenols 2 and 3a–d form highly active catalysts with Ni(1,5‐cod)2 (as does 1) for polymerization of ethylene, whereas phosphanylphenyl ethers do not give catalysts under the same conditions. The reason is the cleavage of the O‐acyl bond upon heating with nickel(0) precursor compounds in the presence of ethylene. The precursors are P‐coordinated Ni0 complexes, which are formed at room temperature, such as 4d obtained from 3d and Ni(cod)2 (in a 2:1 molar ratio), and characterized by multinuclear NMR spectroscopy. Upon heating in the presence of ethylene, the precatalysts are activated. Catalysts 2Ni and 3a–dNi convert ethylene nearly quantitatively, 2Ni slowly, and 3a–dNi rapidly, into linear polyethylene with vinyl and methyl end groups, and in the latter case, C(O)R end groups are also detectable. This proves insertion of Ni0 into the O–C(O)R bond of 3a–d ligands for formation of the primary catalyst. Termination of the first chain growing cycle by β‐hydride elimination changes the mechanism to the phosphanylphenolate–NiH initiated polymerization providing the main body of the polymer. A small retardation in the ethylene consumption rate with 3a–dNi catalysts relative to that observed for 1Ni and stabilization of the catalyst, which gives rise to reproducibly high ethylene conversion, is observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Methyl 2‐(Benzyloxycarbonylamino)‐2‐cyclopropylideneacetate: A Versatile Building Block for Cyclopropyl‐Containing Amino Acids
Authors: Limbach Michael , Lygin Alexander , Es‐Sayed Mazen , de Meijere Armin 
Published: February 2009

AbstractMethyl 2‐(benzyloxycarbonylamino)‐2‐cyclopropylideneacetate (2) was prepared in nine steps starting from L‐serine in an overall yield of 24 %. It has been demonstrated to be reasonably reactive in Michael additions of various nucleophiles (6 examples, 75–98 % yields) as well as Diels–Alder reactions, both leading to new cyclopropyl‐containing amino acids in protected form. An application of 2 in the synthesis of methyl 4‐tert‐butoxycarbonylmethyl‐5‐oxo‐4,7‐diazaspiro[2.5]octane‐8‐carboxylate (15), a precursor for geometrically constrained bicyclic peptidomimetics of type 16, has also been proved.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Trust and respect as mediators of the other‐ and self‐profitable trait effects on interpersonal attraction
Authors: Singh Ramadhar , Simons Joseph J. P. , Young Dawn Patricia C. Y. , Sim Berwine S. X. , Chai Xiau Ting , Singh Smita , Chiou Siao Ying 
Published: February 2009

AbstractMediators of the effects of other‐profitable (e.g., sincere vs. irresponsible) or self‐profitable (e.g., intelligent vs. unintelligent) traits on attraction were investigated. In Experiment 1 (N = 256), valence of a single other‐ or self‐profitable trait was varied, and trust in, respect for, and attraction toward the partner were measured. The three constructs were distinct. Moreover, the effects of the other‐profitable traits on attraction were solely mediated by trust, and those of the self‐profitable traits were mediated more strongly by respect than trust. In Experiment 2 (N = 144), an other‐profitable trait was crossed with the self‐profitable one, and diagnosticity ratings of those traits for the partner's warmth and competence and the previous three responses were taken. The five constructs were empirically distinct. Although trust mediated the effect of other‐profitable trait on attraction, there was a direct effect also. Respect was the sole mediator of the self‐profitable trait effect. Theoretical and methodological implications of these findings are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Quantitative Analysis of Prometrine Herbicide by Liquid–Liquid Extraction Procedures Coupled to Electrochemical Measurements
Authors: Juarez A. V. , Yudi L. M. 
Published: February 2009

AbstractA sensitive method is proposed for the preconcentration and quantification of the herbicide Prometrine (PROM) at a liquid‐liquid interface employing square‐wave voltammetry. The preconcentration stage was based on liquid‐liquid extraction methodology and the PROM quantification was carried out from the peak current of square‐wave voltammograms. Under the experimental conditions employed, linear calibration curves in the concentration range 1.0×10−6 M–5.0×10−5 M, with detection limit equal to 1.5×10−6 M were obtained without pretreatment of the samples. This linear range, as well as detection limit could be extended towards lower concentrations when a pretreatment procedure was employed. In this way, linearity of calibration curves between 8.0×10−8 M and 2.4×10−7 M and detection limit of 1.0×10−7 M, were observed. On the other hand, the standard addition method was also used as an alternative and an appropriated quantification technique for this system. A linear concentration range between 1.0×10−6 M and 2.7×10−5 M, with a correlation coefficient of 0.997, was obtained. This procedure has also a promising application in the separation of herbicides from other interferents, present in real samples, previous to their quantification.
Electrophoretic motion of ideally polarizable particles in a microchannel
Authors: Wu Zhemin , Gao Yandong , Li Dongqing 
Published: February 2009

AbstractThe induced‐charge electrophoretic (ICEP) motion of ideally polarizable particles in a microchannel is numerically studied in this paper. A complete 3‐D multi‐physics model is set up to simulate the transient ICEP motion of spherical ideally polarizable particles in a microchannel. The study shows that a non‐uniform distribution of induced surface charge occurs when an ideally polarizable particle is immersed in an externally applied electric field, resulting in a varying slipping (EOF) velocity along the particle's surface and hence producing micro vortexes in the liquid. The numerical results verify that the steady‐state ICEP velocity of an ideally polarizable particle does not differ from the electrophoretic velocity of a non‐conducting particle, although the flow field near the particle does. A strong wall‐repelling effect of ICEP is found when the polarizable particle is placed close to the channel wall. This is due to the lifting effect generated from the interaction between the induced micro vortexes and the channel wall and depends on the electric field and the particle size. The wall effects on ICEP motion can be used for focusing particles and for separation of particle by density.
Simulations of IEF in microchannel with variable cross‐sectional area
Authors: Chou Yin , Yang Ruey‐Jen 
Published: February 2009

AbstractThis study develops a 1‐D mass transport model to describe the electrophoresis transport behavior within a microchannel with a variable cross‐sectional area. Utilizing three different numerical schemes, simulations are performed to investigate the IEF of proteins in ampholyte‐based pH gradients within both a planar microchannel and a contraction–expansion microchannel, respectively. The simulation results obtained using the modified 1‐D mass transport model and the finite‐volume method (FVM) for the IEF separation of a single protein sample in a ten‐ampholyte‐based pH gradient within a planar microchannel are consistent with those presented by Shim et al. [Electrophoresis 2007, 28, 572–586] using a 2‐D FVM scheme. In addition, the Courant–Friedrichs–Lewy number insensitive conservation element and solution element (CNI‐CESE) method is found to be both more robust and more computationally efficient than the conventional CESE scheme when modeling IEF phenomena within a contraction–expansion microchannel. In modeling the IEF separation of four sample ampholytes in a 20‐ampholtye‐based pH gradient within a contraction–expansion microchannel, the results obtained using the CNI‐CESE scheme are in good agreement with those published in literature. Moreover, the simulations can be performed significantly faster with the new 1‐D model and the CNI‐CESE scheme. Finally, the results obtained using the modified 1‐D mass transport model and the CNI‐CESE scheme demonstrate that the concentration of the focused test sample and the resolution of the pH gradient within the microchannel increase as the number of ampholytes used to accomplish the IEF separation process is increased.
Two‐dimensional protein separation in microfluidic devices
Authors: Chen Hong , Fan Z. Hugh 
Published: February 2009

AbstractProteomics is emerging as an important tool in modern drug discoveries and medical diagnostics. One of the techniques used in proteomics studies is 2‐DE. The process of the conventional 2‐DE is time‐consuming and it has substandard reproducibility. Many efforts have been made to address the limitations, with an aim for fast separation and high resolution. In this paper, we reviewed the work on achieving 2‐DE in microfluidic devices, including individual dimension in one channel, two dimensions in two intersected channels, and 2‐D separation in a large number of channels. We also discussed the need for integrating microvalves within 2‐DE devices to prevent different separation media from contaminating with each other. Although more efforts are required to match the performance of conventional 2‐DE in a slab gel, microfluidics‐based 2‐D separation has a potential to become an alternative in the future.
GelBandFitter – A computer program for analysis of closely spaced electrophoretic and immunoblotted bands
Authors: Mitov Mihail I. , Greaser Marion L. , Campbell Kenneth S. 
Published: February 2009

AbstractGelBandFitter is a computer program that uses non‐linear regression techniques to fit mathematical functions to densitometry profiles of protein gels. This allows for improved quantification of gels with partially overlapping and potentially asymmetric protein bands. The program can also be used to analyze immunoblots with closely spaced bands. GelBandFitter was developed in Matlab and the source code and/or a Windows executable file can be downloaded at no cost to academic users from http://www.gelbandfitter.org.
Numerical calculation of the dielectrophoretic force on a slender body
Authors: Lin Yuan , Shiomi Junichiro , Amberg Gustav 
Published: February 2009

AbstractIn this paper, a model is proposed to numerically calculate the dielectrophoretic (DEP) force acting on a straight slender body in a non‐uniform electric field. The induced charges are assumed to be located along the centerline of the slender body. By enforcing the boundary conditions at the interfaces of the two dielectrics, an integral equations system is obtained with the induced charge densities as unknowns. Based on the calculated induced charge densities, expressions to calculate the DEP force and torque are obtained. The calculated induced charge density of a prolate ellipsoid under a uniform electric field is compared with the analytic solution and an excellent agreement is achieved. The smaller the slenderness (the ratio of maximum radius to length of the slender body), the smaller the error is. The DEP force that a prolate ellipsoid experiences in a general electric field is numerically calculated and compared with the results obtained by the commonly accepted effective dipole moment method. The current model is expected to possess higher accuracy than the effective dipole moment method and to demand less calculation work than the Maxwell stress tensor method.
System effects in sample self‐stacking CZE: Single analyte peak splitting of salt‐containing samples
Authors: Malá Zdena , Gebauer Petr , Boček Petr 
Published: February 2009

AbstractIn CZE one often gets more peaks than the number of sample components. In practice the additional peaks are often left unexplained or assigned to unidentified impurities or system peaks although cases exist when one analyte forms two or more regular distinct zones. One source of such effects are samples with high salt content that are generally assumed to bring higher sensitivity due to the sample self‐stacking mechanism. The subject of this contribution is the theoretical and experimental investigation of the electromigration behavior of salt‐containing samples. It is shown that they can exhibit splitting of the analyte zone into mutually independent parts detectable as well‐developed distinct peaks. Theory based on velocity diagrams and computer simulations reveals that these effects originate in the transient phase of separation where electromigration dispersion profiles and sharp boundaries are formed and evolve. During this, the sample may induce parallel existence of several transient sharp boundaries (including system boundaries) that are simultaneously capable of stacking an analyte. Their electromigration is convergent and depending on whether they merge before the analyte destacks from them, permanent or transient double or multiple peaks are formed. Presented examples of anionic and cationic systems show good agreement with theory. The appearance of multiple peaks can be very variable, ranging from double or triple peaks to a major peak with a minor peak quite apart. Knowledge of the peak‐splitting mechanism allows both to identify its presence in a given BGE and sample and to find effective remedy.
Dual frequency dielectrophoresis with interdigitated sidewall electrodes for microfluidic flow‐through separation of beads and cells
Authors: Wang Lisen , Lu Jente , Marchenko Steven A. , Monuki Edwin S. , Flanagan Lisa A. , Lee Abraham P. 
Published: February 2009

AbstractThis paper presents a novel design and separation strategy for lateral flow‐through separation of cells/particles in microfluidics by dual frequency coupled dielectrophoresis (DEP) forces enabled by vertical interdigitated electrodes embedded in the channel sidewalls. Unlike field‐flow‐fractionation‐DEP separations in microfluidics, which utilize planar electrodes on the microchannel floor to generate a DEP force to balance the gravitational force and separate objects at different height locations, lateral separation is enabled by sidewall interdigitated electrodes that are used to generate non‐uniform electric fields and balanced DEP forces along the width of the microchannel. In the current design, two separate AC electric fields are applied to two sets of independent interdigitated electrode arrays fabricated in the sidewalls of the microchannel to generate differential DEP forces that act on the cells/particles flowing through. Individual particles (cells or beads) will experience DEP forces differently due to the difference in their dielectric properties. The balance of the differential DEP forces from the electrode arrays will position dissimilar particles at distinct equilibrium planes across the width of the channel. When coupled with fluid flow, this results in lateral separation along the width of the microchannel and the separated particles can thus be automatically directed into branched channel outlets leading to different reservoirs for downstream processing. In this paper, we present the design and analysis of lateral separation enabled by dual frequency coupled DEP, and cell/bead and cell/cell separations are demonstrated with this lateral separation strategy. With vertical interdigitated electrodes on the sidewall, the height of the microchannel can be increased without losing the electric field strength in contrast to other multiple frequency DEP devices with planar electrodes. As a result, populations of cells can be separated simultaneously instead of one by one to enable high‐throughput sorting microfluidic devices.
GST polymorphism and excretion of heterocyclic aromatic amine and isothiocyanate metabolites after Brassica consumption
Authors: Steck Susan E. , Hebert James R. 
Published: February 2009

AbstractBrassica vegetable intake has been associated with decreased risk and well‐done meat intake has been associated with increased risk of cancers at multiple organ sites in epidemiologic studies. Experimental studies suggest a role of modulation of phase I and phase II metabolizing enzymes as one mechanism for these associations. Heterocyclic aromatic amines (HAAs) are carcinogens formed in meat that has been cooked to well‐done and at high temperatures. Phase I metabolizing enzymes catalyze the activation of HAAs, and phase II metabolizing enzymes serve to detoxify the active carcinogens. The glutathione S‐transferases (GSTs) are a family of phase II metabolizing enzymes that are induced by, and act to conjugate, isothiocyanates (ITCs), phytochemicals found in Brassica vegetables. This review summarizes the results of feeding studies in humans that examine effects of polymorphisms in GSTs on ITC metabolite excretion, reviews the evidence for modulation of HAA mutagenicity by ITCs, and discusses the need for feeding studies examining potential interactions among polymorphic genes encoding phase I and phase II metabolizing enzymes, meat intake, and Brassica intake to elucidate their role in cancer etiology. Environ. Mol. Mutagen., 2009. © 2009 Wiley‐Liss, Inc.
Archaeological evidence for destructive earthquakes in Sicily between 400 B.C. and A.D. 600
Authors: Bottari Carla , Stiros Stathis C. , Teramo Antonio 
Published: February 2009

AbstractA systematic archaeoseismological study indicates that at least three earthquakes occurred between 400 B.C. and A.D. 600, causing destruction to numerous ancient monuments in Sicily. Evidence for these earthquakes comes from the collapse style of buildings (toppled walls, column drums in a domino‐style arrangement, directional collapses, etc.), and the exclusion of other likely causes for such effects. Dating of inferred earthquakes is based on coins (accurate to within 5–10 years), pottery (accurate to within 50–200 years), and other artifacts. The oldest documented earthquake occurred between 370 and 300 B.C. and caused the collapse of two Greek temples in Selinunte. This otherwise poorly documented event was probably also the cause of extensive destruction in northeastern Sicily in the first century A.D. Destruction of some sites may be assigned to an earthquake that occurred between 360 and 374 and correlates with the A.D. 365 seismic sequence known from historical sources. This study covers a wider region and provides a more precise dating of earthquakes than previous studies. Although it focuses on a certain period (4th–3rd centuries B.C., 4th–7th centuries A.D.), it indicates that the period before A.D. 1000 is not a period of seismic quiescence in Sicily as was previously believed, but to a period characterized by strong and destructive earthquakes. © 2009 Wiley Periodicals, Inc.
Utilization of laser range finder and differential GPS for high‐resolution topographic measurement at Hacituğrul Tepe, Turkey
Authors: Hayakawa Yuichi S. , Tsumura Hiro'omi 
Published: February 2009

AbstractTopographic maps are fundamental for geoarchaeological field studies and archaeological excavations. However, traditional methods of topographic mapping, as well as modern high‐tech methods such as airborne laser scanning and photogrammetry of high‐resolution satellite images, are often cost‐ineffective for field studies in terms of time, money, and labor. We here propose a method to measure topography for archaeological sites and surrounding areas quickly and accurately, using a laser range finder (LRF) and differential global positioning system DGPS. Three‐dimensional coordinates of points on land surfaces are measured through the LRF, targeted from multiple measuring locations whose positions are acquired with the DGPS. The point data are then interpolated to produce a digital elevation model (DEM) using a geographic information system (GIS). High‐resolution DEMs can be obtained with this method, with horizontal and vertical accuracies on the order of 10 cm. We here demonstrate the method for measuring detailed topography of the Hacituğrul Tepe in central Turkey. Digital topography data incorporated in GIS can also be part of an archaeological database, providing opportunities for quantitative analyses of topography and archaeological materials. © 2009 Wiley Periodicals, Inc.
The VE‐cadherin binding domain of fibrinogen induces endothelial barrier permeability and enhances transendothelial migration of malignant breast epithelial cells
Authors: Sahni Abha , Arévalo Maria T. , Sahni Sanjeev K. , Simpson‐Haidaris Patricia J. 
Published: February 2009

AbstractFibrin deposition and exudation of plasma fibrinogen (Fg) have long been recognized as hallmarks of inflammation, cardiovascular disease and neoplasia. The Fg‐β15–42 domain binds to the endothelial cell adhesion molecule, VE‐cadherin, promoting endothelial cell proliferation, angiogenesis and leukocyte diapedesis. Furthermore, spontaneous blood‐borne and lymphatic metastasis of some types of tumor emboli requires plasma fibrin(ogen); however, the molecular mechanisms by which this occurs are poorly understood. We sought to determine whether Fg‐β15–42 and VE‐cadherin binding interactions promote endothelial barrier permeability and breast cancer cell transendothelial migration (TEM) using transwell insert culture systems. Synthetic peptides containing/missing residues β15–17 critical for Fg‐β15–42 binding to VE‐cadherin, and antibodies that bind to Fg‐β15–21 (T2G1) and VE‐cadherin (BV9) were used to induce or inhibit Fg‐mediated permeability and TEM. Fg induced dose‐dependent permeability of human umbilical vein and microvascular endothelial but not epithelial cell barriers. Maximal Fg‐induced endothelial permeability required Fg‐β15–42 and VE‐cadherin‐binding interactions involving Fg‐β15–17. Fg‐induced TEM of malignant MDA‐MB‐231 and MCF‐7 breast cancer cells also required Fg‐β15–42 and VE‐cadherin binding; however, such TEM was independent of E‐cadherin or estrogen receptor expression. In contrast, Fg did not induce TEM of nonmalignant MCF‐10A breast epithelial cells. Fg‐induced endothelial permeability was retained in the presence of MDA‐MB‐231 but inhibited in the presence of MCF‐10A cells. It is intriguing to speculate that loss of Fg‐β15–42 binding by premalignant breast epithelial cells serves as a molecular switch to induce a highly aggressive, metastatic breast cancer phenotype. Hence, Fg‐β15–42 represents a potential molecular target for therapeutic intervention of breast cancer metastasis. © 2009 UICC