bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Integrated Catalytic and Transient Study of Sulfated Zirconias: Investigation of the Reaction Mechanism and the Role of Acidic Sites in n‐Butane Isomerization
Authors: Breitkopf Cornelia 
Published: September 2009

AbstractThe transient temporal analysis of products (TAP) pulse method has been applied to investigate the isomerization of n‐butane on sulfated zirconias at very low pressure. By combining these results with findings from XRD, XPS, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), temperature‐programmed desorption (TPD), and catalytic studies at atmospheric pressure, a wide range of pressure conditions can be accessed to study the influence of surface sulfate groups on the isomerization activity and the mechanism of this reaction. The catalytic activity of powder catalysts has been correlated to the surface site density of sulfates, with pyrosulfate structures playing a major role in the initiation of the reaction. The complex interplay between sulfate‐free and sulfate‐covered zirconia surfaces for the adsorption of alkanes has been investigated in detail, with TAP pulse experiments showing a monomolecular reaction pathway at low n‐butane partial pressures. Moreover, TAP pulse experiments have allowed detection of the reaction products of this initiation process, including butene and water, and have shown their influence on the deactivation of sulfated zirconias. Heats of adsorption have been calculated from the TAP pulse experiments.
New Nanocrystalline Cu/MnOx Catalysts Prepared from Supercritical Antisolvent Precipitation
Authors: Tang Zi‐Rong , Jones Christopher D. , Aldridge James K. W. , Davies Thomas E. , Bartley Jonathan K. , Carley Albert F. , Taylor Stuart H. , Allix Mathieu , Dickinson Calum , Rosseinsky Matthew J. , Claridge John B. , Xu Zhongling , Crudace Mandy J. , Hutchings Graham J. 
Published: September 2009

AbstractSupercritical CO2 is used as an antisolvent to precipitate out nanostructured homogeneous mixtures of Cu2+ and Mn3+ with crystallites of 10–20 nm in diameter. Following calcination, this material forms a crystalline tetragonal spinel, CuMn2O4, with a branched chainlike structure with a length of 160–200 nm and diameters of approximately 40 nm. This new material is more than twice as active per unit surface area as the conventionally prepared hopcalite catalysts for the oxidation of carbon monoxide. This is the first time that homogeneous mixed oxides have been formed using this method.
Guest‐Driven Luminescence: Lanthanide‐Based Host–Guest Systems with Bimodal Emissive Properties Based on a Guest‐Driven Approach
Authors: Wang Ping , Ma Jian‐Ping , Dong Yu‐Bin 
Published: September 2009

AbstractA series of discrete closed, semi‐closed, and polymeric lanthanide‐based [{Ln(H2O)8}3+⊂LnIII2L4] host–guest systems with tetragonal prism‐like structure have been designed and synthesized through the ligand‐dominated approach. These nanoscopic cages are robust and can be maintained upon guest exchange. Within the restricting space, the luminescence intensity of the encapsulated [Ln(H2O)8]3+ species is dramatically enhanced due to the vibrational movements originating from the OH oscillators in the coordinated water molecules being effectively reduced by the host–guest H‐bonding interactions. Based on the guest‐driven approach, tunable emission and bimodal emission (UV/Vis/NIR) of these [{Ln(H2O)8}3+⊂LnIII2L4] supramolecular systems are successfully realized. Moreover, the strong luminescence originating from [{Ln(H2O)8}3+⊂LnIII2L4] host–guest system can be quenched by encapsulation of d‐block metal quenchers, such as Fe3+ and Cu2+, through solid‐state f–d metal exchange. Additionally, this study demonstrates that the photoinduced solid‐state guest‐independent emission spectrum could be one of the most diagnostic techniques for monitoring the solid‐state guest‐exchange process.
Shape, Size, and Phase‐Controlled Rare‐Earth Fluoride Nanocrystals with Optical Up‐Conversion Properties
Authors: Zhang Fan , Li Jing , Shan Jiong , Xu Lei , Zhao Dongyuan 
Published: September 2009

AbstractHigh‐quality rare‐earth fluorides, α‐NaMF4 (M=Dy, Ho, Er, Tm, Y, Yb, and Lu) nanocrystals and β‐NaMF4 (M=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y, Yb, and Lu) nanoarrays, have been synthesized by using oleic acid as a stabilizing agent through a facile hydrothermal method at 130–230 °C. The phase, shape, and size of the products are varied by careful control of synthetic conditions, including hydrothermal temperature and time, and the amounts of reactants and solvents. Tuning the hydrothermal temperature, time, and the amount of NaOH can cause the transformation from the cubic α‐NaMF4 to hexagonal phase β‐NaMF4. Upon adjustment of the amount of NaOH, NaF, M3+, and ethanol, the morphologies for the β‐NaMF4 nanoarrays can range from tube, rod, wire, and zigzagged rod, to flower‐patterned disk. Simultaneously, the size of the rare‐earth fluoride crystals is variable from 5 nm to several micrometers. A combination of “diffusion‐controlled growth” and the “organic–inorganic interface effect” is proposed to understand the formation of the nanocrystals. An ideal “1D growth” of rare‐earth fluorides is preferred at high temperatures and high ethanol contents, from which the tube‐ and rodlike nanoarrays with high aspect ratio are obtained. In contrast, the disklike β‐NaMF4 nanoarrays with low aspect ratios are produced by decreasing the ethanol content or prolonging the reaction time, an effect probably caused by “1D/2D ripening”. Multicolor up‐conversion fluorescence is also successfully realized in the Yb3+/Er3+ (green, red) and Yb3+/Tm3+ (blue) co‐doped α‐NaYF4 nanocrystals and β‐NaYF4 nanoarrays by excitation in the NIR region (980 nm).
Vicinal Dinitridoruthenium‐Substituted Polyoxometalates γ‐[XW10O38{RuN}2]6− (X=Si or Ge)
Authors: Besson Claire , Musaev Djamaladdin G. , Lahootun Vanina , Cao Rui , Chamoreau Lise‐Marie , Villanneau Richard , Villain Françoise , Thouvenot René , Geletii Yurii V. , Hill Craig L. , Proust Anna 
Published: September 2009

AbstractReaction of the divacant polyoxometalate K8[γ‐XW10O36] (X=Si, Ge) with two equivalents of the metal‐nitrido precursor Cs2[RuVINCl5], at room temperature in water, produces K2(Me2NH2)2H2[γ‐XW10O38{RuN}2], X=Si (DMA‐1 a) or Ge (DMA‐1 b). The X‐ray crystal structures of both complexes show monomeric complexes with highly unusual vicinal terminal metal‐nitrido units. The RuN bond lengths are 1.594(10) and 1.612(11) Å in 1 a and 1 b, respectively. EXAFS studies confirmed the key structural assignments from X‐ray crystallography. The XANES spectrum of DMA‐1 a, diamagnetism, NMR (29Si and 183W) chemical shifts, voltammetric behavior, reductive titrations with [PW12O40]4−, and computational data are all consistent with d2 RuVI centers in these complexes. The FT‐IR and Raman spectra show the expected vibrational modes of the {γ‐XW10} unit and the RuN stretch at 1080 cm−1, respectively. Interestingly, reduction of DMA‐1 a by 4 equivalents of [PW12O40]4− produces NH3 in nearly quantitative yield. Cyclic voltammetry versus pH and calculations provide the energetics for the possible two‐electron reduction and two‐proton addition processes in this reaction.
Facile Synthesis of Nitrogen Tetradentate Ligands and Their Applications in CuI‐Catalyzed N‐Arylation and Azide–Alkyne Cycloaddition
Authors: Li Fuwei , Hor T. S. Andy 
Published: September 2009

AbstractFive new tetradentate ligands [NNNN] with benzimidazolyl‐imine or amine nitrogen donors have been synthesized in good yields under mild conditions from easily available substrates. trans‐N,N′‐bis(1‐Ethyl‐2‐benzimidazolylmethylene)cyclohexane‐1,2‐diimine is the best accelerating ligand in this series that supports the CuI‐catalyzed Ullmann N‐arylation and the direct three‐component azide–alkyne cycloaddition reaction to give the corresponding substituted imidazole, pyrazole, and triazole in high yields. Single‐crystal X‐ray diffraction analysis of its complex with CuI reveals a novel one‐dimensional coordination polymer of the metal chain bridged alternately by the [NNNN] ligand and diiodides.
From Racemic Compound to Spontaneous Resolution: A Linker‐Imposed Evolution of Chiral [MnMo9O32]6−‐Based Polyoxometalate Compounds
Authors: Tan Huaqiao , Li Yangguang , Chen Weilin , Liu Ding , Su Zhongmin , Lu Ying , Wang Enbo 
Published: September 2009

AbstractFive compounds based on [MnMo9O32]6−: (Himi)6[MnMo9O32] (1) (imi=imidazole), Na2(Himi)4[MnMo9O32]⋅2 H2O (2), Na3(Himi)3[MnMo9O32] (3), D‐NH4Mn2.5[MnMo9O32]⋅11 H2O (4 a), and L‐NH4Mn2.5[MnMo9O32]⋅11 H2O (4 b) were prepared and characterized. X‐ray crystallographic analysis revealed that compounds 1 and 2 with imidazole molecules as linkers are racemic compounds; compound 3 is a racemic solid solution of Na+ cations and the polyoxoanion [MnMo9O32]6−; and compounds 4 a and 4 b are enantiomers. In compound 4, the homochiral polyoxoanions [MnMo9O32]6− are connected by Mn2+ cations to form a unique (45⋅6)(47⋅68) topology net framework. By adjusting the linkers from imidazole molecules to Na+ and finally Mn2+ cations, the chiral polyoxoanions [MnMo9O32]6− were changed from a racemic compound to a conglomerate. This means that spontaneous resolution can be efficiently realized by connecting homochiral polyoxoanions into one‐dimensional (1D), 2D, and 3D structures, with an emphasis on using appropriate linkers with substantial interaction strength, directionality, and enantioselectivity.
Mechanism of Electrocyclic Ring‐Opening of Diphenyloxirane: 40 Years after Woodward and Hoffmann
Authors: Friedrichs Jana , Frank Irmgard 
Published: September 2009

AbstractThe photochemistry of diphenyloxirane has been investigated by using static density functional theory and first‐principles molecular dynamics. We optimised potential‐energy surfaces for both the disrotatory and the conrotatory pathway in the first excited state. Although the disrotatory pathway does not seem to be favoured energetically, we get only the disrotatory product during the molecular dynamics simulations. This can be attributed to the “on‐the‐fly” description of the electronic structure in a first‐principles molecular dynamics simulation. The different photochemical behaviour of aryl oxiranes and unsubstituted oxirane is due to different shapes of the frontier orbitals.
Palladium(II) Complexes of New Bulky Bidentate Phosphanes: Active and Highly Regioselective Catalysts for the Hydroxycarbonylation of Styrene
Authors: Frew Jamie J. R. , Damian Karen , Van Rensburg Hendrik , Slawin Alexandra M. Z. , Tooze Robert. P. , Clarke Matthew L. 
Published: September 2009

AbstractThe synthesis of four new bulky bidentate phosphines that possess both tert‐butyl and trifluoromethylphenyl substituents is described. Symmetric ligands were readily obtained by alkylation of phosphidoboranes of the type Li[P(BH3)(tBu)(Ar)] with dihaloalkanes. Non‐symmetric ligands were prepared from a new stable precursor, tBu2P(BH3)(CH2)3Br, that should prove useful for other ligand syntheses. Palladium(II) complexes of the four new ligands were prepared and were characterised by spectroscopic methods, microanalysis and X‐ray crystallography. The new [PdCl2(L)] complexes were evaluated as catalysts for the hydroxycarbonylation of styrene and found to give unprecedented regioselectivity and yields for a diphosphine‐based catalyst. A study on promoter effects reveals that the presence of acid and chloride is necessary to achieve such selectivities. It has been proposed in the literature that such conditions result in a new pathway in which styrene is converted into 2‐phenethyl chloride, with the latter being the real substrate in the reaction. However, a deuterium labelling study seems to rule out this mechanism, at least under the conditions used herein.
Germa‐closo‐dodecaborate: A New Ligand in Transition‐Metal Chemistry with a Strong trans Influence
Authors: Dimmer Jörg‐Alexander , Schubert Hartmut , Wesemann Lars 
Published: September 2009

AbstractThe strong nucleophilic character of germa‐closo‐dodecaborate towards late transition metal centres is described. The synthesis and characterisation of the first germa‐closo‐dodecaborate complexes are presented, and the solid state structures of the germaborate transition metal complexes were determined by X‐ray crystal structure analyses. The strong trans influence of the new germaborate ligand was determined by IR spectroscopy and NMR coupling constants.
Isolation and Structural X‐ray Investigation of Perfluoroalkyl Derivatives of Six Cage Isomers of C84
Authors: Tamm Nadezhda B. , Sidorov Lev N. , Kemnitz Erhard , Troyanov Sergey I. 
Published: September 2009

AbstractPerfluoroalkylation of a higher fullerene mixture with CF3I or C2F5I, followed by HPLC separation of CF3 and C2F5 derivatives, resulted in the isolation of several C84(RF)n (n=12, 16) compounds. Single‐crystal X‐ray crystallography with the use of synchrotron radiation allowed structure elucidation of eight C84(RF)n compounds containing six different C84 cages (the number of the C84 isomer is given in parentheses): C84 (23)(C2F5)12 (I), C84 (22)(CF3)16 (II), C84 (22)(C2F5)12 (III), C84 (11)(C2F5)12 (IV), C84 (16)(C2F5)12 (V), C84 (4)(CF3)12 (VI with toluene and VII with hexane as solvate molecules), and C84 (18)(C2F5)12 (VIII). Whereas some connectivity patterns of C84 isomers (22, 23, 11) had previously been unambiguously confirmed by different methods, derivatives of C84 isomers numbers 4, 16, and 18 have been investigated crystallographically for the first time, thus providing direct proof of the connectivity patterns of rare C84 isomers. General aspects of the addition of RF groups to C84 cages are discussed in terms of the preferred positions in the pentagons under the formation of chains, pairs, and isolated RF groups.
Highly Enantioselective Conjugate Additions of Phosphites to α,β‐Unsaturated N‐Acylpyrroles and Imines: A Practical Approach to Enantiomerically Enriched Amino Phosphonates
Authors: Zhao Depeng , Wang Yuan , Mao Lijuan , Wang Rui 
Published: September 2009

AbstractThe first highly enantioselective phosphonylation of α,β‐unsaturated N‐acylpyrroles has been developed. Excellent yields (91–99 %) and enantioselectivities (up to >99 % enantiomeric excess (ee)) were observed for a broad spectrum of both phosphites and N‐acylpyrroles under mild conditions. In particular, when diethyl phosphite was employed to test the scope of the N‐acylpyrroles, almost optically pure products (98 to >99 % ee) were obtained for 20 examples of N‐acylpyrroles. Moreover, optically pure α‐substituted β‐ or γ‐amino phosphonates can be obtained by several simple transformations of the pyrrolyl phosphonates. The versatility of the N‐acylpyrrole moiety makes the phosphorus adducts powerful chiral building blocks that enable the synthesis of various phosphonate‐containing compounds. Finally, the present strategy can also be applied to the asymmetric hydrophosphonylation of N‐acylimines with high enantioselectivities (93 to >99 % ee).
Fraktionierung pflanzlicher Rohstoffe zur simultanen Erzeugung von Lebensmitteln, technischen Rohstoffen und Energieträgern
Authors: Menner M. , Müller K. , Pickardt C. , Eisner P. 
Published: September 2009

AbstractIn Zeiten von Ressourcenknappheit und einer stetig anwachsenden Belastung der Atmosphäre mit Kohlendioxid ist die Nutzung pflanzlicher Rohstoffe ein wichtiger Lösungsansatz. Die Lebensmittelverfahrenstechnik eröffnet mit maßgeschneiderten Fraktionierungsverfahren für pflanzliches Rohmaterial ein großes Potenzial zur Gewinnung wertvoller Inhaltsstofffraktionen, die zur Energiegewinnung, im Lebens‐ und Futtermittelbereich und als technische Rohstoffe in der chemischen und pharmazeutischen Industrie eingesetzt werden können. Der Beitrag gibt einen Überblick über Produktion und Einsatz pflanzlicher Rohstoffe in Deutschland und zeigt am Beispiel der Ölsamen detailliert Fraktionierungsverfahren und ‐strategien auf. Neben der Beschreibung von Verfahren zur Gewinnung von Öl, Proteinen, Kohlenhydraten und Polyphenolen werden Beispiele für deren Anwendung gegeben.
The Emerging Therapeutic Potential of Histone Methyltransferase and Demethylase Inhibitors
Authors: Spannhoff Astrid , Hauser Alexander‐Thomas , Heinke Ralf , Sippl Wolfgang , Jung Manfred 
Published: September 2009

AbstractEpigenetics is defined as heritable changes to the transcriptome that are independent of changes in the genome. The biochemical modifications that govern epigenetics are DNA methylation and posttranslational histone modifications. Among the histone modifications, acetylation and deacetylation are well characterized, whereas the fields of histone methylation and especially demethylation are still in their infancy. This is particularly true with regard to drug discovery. There is strong evidence that these modifications play an important role in the maintenance of transcription as well as in the development of certain diseases. This article gives an overview of the mechanisms of action of histone methyltransferases and demethylases, their role in the formation of certain diseases, and available inhibitors. Special emphasis is placed on the strategies that led to the first inhibitors which are currently available and the screening approaches that were used in that process.
Homoharringtonine, omacetaxine mepesuccinate, and chronic myeloid leukemia circa 2009
Authors: Quintás‐Cardama Alfonso , Kantarjian Hagop , Cortes Jorge 
Published: September 2009

AbstractHomoharringtonine (HHT) is a natural alkaloid that is obtained from various Cephalotaxus species. The mechanism of action by which HHT exerts its antitumor activity is through inhibition of protein synthesis and promotion of apoptosis. In the 1990s, HHT proved to be significantly active as salvage therapy for patients with chronic myeloid leukemia (CML) after failure on interferon‒α therapy. However, the remarkable success of imatinib mesylate in the treatment of CML relegated HHT to oblivion. The development of omacetaxine mepesuccinate, a subcutaneously bioavailable semisynthetic form of HHT, and its activity in imatinib‐resistant CML has established this agent for the second time as a valuable option in the management of this disease. Preliminary results appear to support the use of this agent for patients who have imatinib‐resistant CML, including those who carry the tyrosine kinase inhibitor‐insensitive mutation that exchanges the amino acids threonine and isoleucine at position 315 (the T315I mutation). In this article, the authors discuss the current data on omacetaxine and the prospects of this agent to be integrated into the state‐of‐the‐art treatment algorithms for CML. Cancer 2009. © 2009 American Cancer Society.
Modified core wash cytology procedure for the immediate diagnosis of core needle biopsies of breast lesions
Authors: Wauters C. A. P. , Sanders‐Eras C. T. , Kooistra B. W. , Strobbe L. J. A. 
Published: September 2009

AbstractBACKGROUND:Core wash or touch imprint cytology is often used to obtain a quick, preliminary diagnosis on a core needle biopsy (CNB) of breast lesions, essential for the management of the 1‐day breast clinic. Contradictory results of both techniques in the literature led to this preclinical study investigating an alternative method of touch imprint and core wash cytology.METHODS:Thirty breast lesions were biopsied by a core needle in a laboratory setting. The CNBs were collected in RPMI fluid (Roswell Park Memorial Institute fluid). The touch imprint cytology was performed taking the biopsy out of the fluid and smearing it on a microscopic slide and May‐Grunwald Giemsa stained. The core wash cytology was made by fixating the remaining cells in Fixcyt and prepared with a liquid‐based preparation method and Papanicolaou stained. The cytologic findings were categorized into benign, atypical favoring benign, atypical, suspicious, and malignant and compared with the histologic CNB results.RESULTS:The CNBs showed 20 of 30 samples to be malignant, 2 to be phylloides tumors, 7 to be benign, and 1 to be unsatisfactory. Both techniques showed a sensitivity of 95% and specificity of 100%. Touch imprint yielded insufficient diagnoses (13.3%), compared with core wash (6.6%). Of the core wash cases, 86% showed a good quality versus 30% in touch imprint cytology.CONCLUSIONS:This preclinical study on modified touch imprint and core wash techniques led to results that were comparable to or better than those in the literature. The core wash cytology is preferred to touch imprint because of the better morphology. Cancer (Cancer Cytopathol) 2009. © 2009 American Cancer Society.
Performance‐based scheduling strategies for HTC applications in complex federated grids
Authors: Leal Katia , Huedo Eduardo , Llorente Ignacio M. 
Published: September 2009

AbstractThe main purpose of the present study is to analyze the suitability of performance‐based scheduling strategies for High Throughput Computing applications applied to Federated Grids consisting of several Grid infrastructures. The infrastructures forming aFederated Grid are classified as internal or external. This is because our scheduling policies map as much jobs as possible first to internal resources. In this way the mapping strategies save time and communication bandwidth by exploiting the location of the internal resources and the membership to their respective resource domains. At the same time, the policies avoid overloading external resources facilitating the cooperation between organizations to share resources. In this paper we consider three new algorithms for scheduling in situations where there are several Grid infrastructures of different types: enterprise, partner, or utility. Copyright © 2009 John Wiley & Sons, Ltd.
An optimized flow cytometry protocol for analysis of angiogenic monocytes and endothelial progenitor cells in peripheral blood
Authors: Hristov Mihail , Schmitz Susanne , Schuhmann Christoph , Leyendecker Thorsten , von Hundelshausen Philipp , Krötz Florian , Sohn Hae‐Young , Nauwelaers Frans A. , Weber Christian 
Published: September 2009

AbstractCirculating adult CD34+VEGFR2+ endothelial progenitor cells (EPCs) have been shown to differentiate into endothelial cells, thus contributing to vascular homeostasis. Furthermore, a subset of circulating CD14+ monocytes coexpresses CD16 together with the angiopoietin receptor Tie2 and has been functionally implicated in tumor angiogenesis. However, clinically applicable protocols for flow cytometric quantification of EPCs and Tie2+ monocytes in peripheral blood and a consensus on reference values remain elusive. The number of Tie2+CD14+CD16mid angiogenic monocytes and CD34+VEGFR2+CD45low/− EPCs was assessed in the peripheral venous blood of patients with stable coronary artery disease by three‐color flow cytometry using specific monoclonal antibodies conjugated to PerCP, PE, PE‐Cy7, APC, and APC‐Cy7. Scatter multigating with exclusion of dead cells was performed to dissect complex mononuclear cell populations. This analysis was further refined by matching bright fluorochromes (PE‐Cy7, PE, APC) with dimly expressed markers (CD34, VEGFR2, Tie2), by automatic compensation for minimizing fluorescence spillover and by using fluorescence‐minus‐one (FMO) controls to determine positive/negative boundaries. Presuming a Gaussian distribution, we obtained average values (mean ± SD) of 1.45 ± 1.29% for Tie2+CD14+CD16mid monocytes (n = 11, range: 0.12–3.64%) and 0.019 ± 0.013% for CD34+VEGFR2+CD45low/− EPCs (n = 17, range: 0.003–0.042%). The intra‐ and inter‐assay variability was 1.6% and 4.5%, respectively. We have optimized a fast and sensitive assay for the flow cytometric quantification of circulating angiogenic monocytes and EPCs in cardiovascular medicine. This protocol may represent a basis for standardized analysis and monitoring of these cell subsets to define their normal range and prognostic/diagnostic value in clinical use. © 2009 International Society for Advancement of Cytometry