bluuebunny/crossref_metadata_2025_split huggingface dataset:
Im Dienste der Wissenschaft: Der Centro de estudios históricos und die Begründung eines liberalen Nationalbewußtseins in Spanien (1910–1936)
Authors: López Sánchez José María 
Published: June 2006

AbstractIn the Name of Science: the Centro de Estudios Históricos and the shaping of a liberal national conciousness in Spain (1910–1936). – The Centro de Estudios Históricos was founded in 1910 by the Junta para Ampliación de Estudios. The main goal was to create a modern scientific system, but the researchers of the Centro also attempted to reinterpret some aspects of the Spanish Culture. We also try to have a new insight into how Spanish History and Culture was apprehended by those intelectuals in order to create the cultural basis of a new Spanish nationalism. The philological school of Menéndez Pidal or the historical school of Sánchez‐Albornoz played an active role in trying to find out the cultural roots of the Spanish Culture. They strived for providing the Spanish nation a cultural background.
An assay for inorganic mercury(II) based on its post‐catalytic enhancement effect on the potassium permanganate–luminol system
Authors: Hu Shangwei , Liu Weibing , Huang Yuming , Shu Weiqun , Cao Jia 
Published: June 2006

AbstractA strong chemiluminescence (CL) response is observed when potassium permanganate solution is injected into basic luminol solution. When the CL reaction terminates, subsequent injection of Hg2+ solution into the reaction mixture results in a new CL reaction. Based on the post‐catalytic enhancement effect of Hg2+ on the potassium permanganate–luminol system in basic media, a fast and simple CL‐coupled flow injection analysis for the determination of Hg2+ was developed. In optimum conditions, CL intensity is proportional to Hg2+ concentration over the range 1.0 × 10−8–1.0 × 10−5 g/mL, with a detection limit of 2.0 × 10−9 g/mL. The relative standard deviation (RSD) is 3.6% for 1.0 × 10−7 g/mL Hg2+ (n = 11). After pretreatment with sulphydryl cotton fibre, environmental water samples were analysed by the proposed method for total mercury determination with satisfactory results. The results were in good agreement with those given by hydride generation–cold vapour atomic absorption spectrometry (HG–CVAAS). Copyright © 2006 John Wiley & Sons, Ltd.
Synthetic Ligands Able to Interact with the P53 Tetramerization Domain. Towards Understanding a Protein Surface Recognition Event
Authors: Martinell Marc , Salvatella Xavier , Fernández‐Carneado Jimena , Gordo Susana , Feliz Miguel , Menéndez Margarita , Giralt Ernest 
Published: June 2006

AbstractThe applied interaction of synthetic molecules with defined regions of protein surfaces is an emerging strategy for the modulation of protein activity and/or stability. In spite of recent advances, the design of these molecules is not trivial. Among the most challenging aspects in designing these compounds is that they must compete with water molecules for interaction with polar patches of protein surfaces. Herein is reported the preparation of an arginine‐rich peptide that interacts in aqueous solution with a very hydrophilic patch at the surface of the tetramerization domain of the tumor suppressor protein p53. The interaction has been studied by several complementary techniques. By using this peptide as a template, a library of peptides has been prepared and evaluated in order to examine the different factors that contribute to the recognition event. The conclusions extracted from this work could be useful for the design of ligands directed at highly hydrophilic protein surface patches.
Inactivation of gilGT, Encoding a C‐Glycosyltransferase, and gilOIII, Encoding a P450 Enzyme, Allows the Details of the Late Biosynthetic Pathway to Gilvocarcin V to be Delineated
Authors: Liu Tao , Kharel Madan Kumar , Fischer Carsten , McCormick Andrew , Rohr Jürgen 
Published: June 2006

AbstractResequencing of the gilGT gene, which encodes a putative glycosyltransferase (GT) that is 495 amino acids (aa) long, from the Streptomyces griseoflavus Gö3592 gilvocarcin V (GV) gene cluster, revealed that the previously reported gilGT indeed contains two genes. These are the larger gilGT, which encodes the C‐glycosyltransferase GilGT (379 aa), and the smaller gilV gene, which encodes an enzyme of unknown function (116 aa). The gene gilV is located immediately upstream of gilGT in the GV gene cluster. In‐frame deletion of gilGT created a mutant that accumulated defucogilvocarcin E (defuco‐GE). The result proves the function of GilGT as a C‐glycosyltransferase. Deletion of gilOIII, which is located immediately downstream of gilGT, led to a mutant that accumulated gilvocarcin E (GE). This confirms that the corresponding P450 enzyme, GilOIII, is involved in the vinyl‐group formation of GV. Cross‐feeding experiments in which GE, defuco‐GE, and defucogilvocarcin V (defuco‐GV) were fed to an early blocked mutant of the GV biosynthetic pathway, showed that neither GE nor any of the defuco‐ compounds was an intermediate of the pathway.
Expanding the Substrate Scope of Enzymes: Combining Mutations Obtained by CASTing
Authors: Reetz Manfred T. , Carballeira José Daniel , Peyralans Jérôme , Höbenreich Horst , Maichele Andrea , Vogel Andreas 
Published: June 2006

AbstractIn a previous paper, the combinatorial active‐site saturation test (CAST) was introduced as an effective strategy for the directed evolution of enzymes toward broader substrate acceptance. CASTing comprises the systematic design and screening of focused libraries around the complete binding pocket, but it is only the first step of an evolutionary process because only the initial libraries of mutants are considered. In the present study, a simple method is presented for further optimization of initial hits by combining the mutational changes obtained from two different libraries. Combined lipase mutants were screened for hydrolytic activity against six notoriously difficult substrates (bulky carboxylic acid esters) and improved mutants showing significantly higher activity were identified. The enantioselectivity of the mutants in the hydrolytic kinetic resolution of two substrates was also studied, with the best mutant–substrate combination resulting in a selectivity factor of E=49. Finally, the catalytic profile of the evolved mutants in the hydrolysis of simple nonbranched carboxylic acid esters, ranging from acetate to palmitate, was studied for theoretical reasons.
Structural Studies of 1‐Butyl‐3‐methylimidazolium Tetrafluoroborate/TX‐100/ p‐Xylene Ionic Liquid Microemulsions
Authors: Gao Yan'an , Zhang Jin , Xu Hongyan , Zhao Xueyan , Zheng Liqiang , Li Xinwei , Yu Li 
Published: June 2006

AbstractThe ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate (bmimBF4) forms nonaqueous microemulsions with p‐xylene, with the aid of the nonionic surfactant TX‐100. The phase behavior of the ternary system is investigated, and three microregions of the microemulsions—ionic liquid‐in‐oil (IL/O), bicontinuous, and oil‐in‐ionic liquid (O/IL)—are identified by conductivity measurements, according to percolation theory. On the basis of a phase diagram, a series of IL/O microemulsions are chosen and characterized by dynamic light scattering (DLS). The size of aggregates increases on increasing the amount of added polar component (bmimBF4), which is a similar phenomenon to that observed for typical water‐in‐oil (W/O) microemulsions, suggesting the formation of IL/O microemulsions. The microstructural characteristics of the microemulsions are investigated by FTIR and 1H NMR spectroscopy. The results indicate that the interaction between the electronegative oxygen atoms of the oxyethylene (OE) units in TX‐100 and the electropositive imidazolium ring may be the driving force for the solubilization of bmimBF4 into the core of the TX‐100 aggregates. In addition, the micropolarity of the microemulsions is investigated by using methyl orange (MO) as a UV/Vis spectroscopic probe. A relatively constant polarity of the microemulsion droplets is obtained in the IL microemulsion. Finally, a plausible structure for the IL/O microemulsion is presented.
Oriented Ensembles in Ultrafast Electron Diffraction
Authors: Baskin J. Spencer , Zewail Ahmed H. 
Published: June 2006

AbstractElectron scattering expressions are presented which are applicable to very general conditions of implementation of anisotropic ultrafast electron diffraction (UED) experiments on the femto‐ and picosecond time scale. “Magic angle” methods for extracting from the experimental diffraction patterns both the isotropic scalar contribution (population dynamics) and the angular (orientation‐dependent) contribution are described. To achieve this result, the molecular scattering intensity is given as an expansion in terms of the moments of the transition‐dipole distribution created by the linearly polarized excitation laser pulse. The isotropic component (n=0 moment) depends only on population and scalar internuclear separations, and the higher moments reflect bond angles and evolve in time due to rotational motion of the molecules. This clear analytical separation facilitates assessment of the role of experimental variables in determining the influence of anisotropic orientational distributions of the molecular ensembles on the measured diffraction patterns. Practical procedures to separate the isotropic and anisotropic components of experimental data are evaluated and demonstrated with application to reactions. The influence of vectorial properties (bond angles and rotational dynamics) on the anisotropic component adds a new dimension to UED, arising through the imposition of spatial order on otherwise randomly oriented ensembles.
Mauer und Wand: Teil 1
Authors: Bode Udo F. W. 
Published: June 2006

AbstractWände wurden historisch der ihnen zugedachten Funktion als Mauern und Wände unterschieden. Die Mauern stellten als Außenwände die Begrenzung von innen und außen dar, und ihnen wurden Tragfunktionen zugeordnet. Im Unterschied dazu dienten die Innenwände vorrangig der Raumunterteilung ohne deutliche Tragfunktion. Die stärkere Differenzierung nach einwirkenden Kräften und der Ermittlung empirischer Stabilitätskriterien führte während des 17. bis führen 19. Jh. zu unserem heutigen Verständnis, nach tragenden und raumbegrenzenden Wänden zu unterscheiden. Nachfolgend wird eine kurze Übersicht dieser Entwicklung aufgezeigt.
Bapx1 homeobox gene gain‐of‐function mice show preaxial polydactyly and activated Shh signaling in the developing limb
Authors: Tribioli Carla , Lufkin Thomas 
Published: June 2006

AbstractTo explore Bapx1 homeobox gene function in embryonic control of development, we employed a gain‐of‐function approach to complement our previous loss‐of‐function mutant analysis. We show that transgenic mice overexpressing Bapx1 are affected by skeletal defects including hindlimb preaxial polydactyly and tibial hypoplasia. Bapx1 overexpression generates limb anteroposterior patterning defects including induction of Shh signaling and ectopic activation of functions downstream of Shh signaling into the anterior region of the autopod. Moreover, Bapx1 overexpression stimulates formation of limb prechondrogenic condensations. We also show that Shh is reciprocally able to activate Bapx1 expression in mouse embryos as the orthologous hedgehog (hh) does with the bagpipe/Bapx1 gene in Drosophila. Our results indicate that Bapx1 can modulate appendicular skeletal formation, that the genetic hierarchy between Shh/hh and Bapx1/bagpipe has been conserved during evolution, and that in mouse embryos these two genes can influence one another in a genetically reciprocal manner. We conclude that it is reasonable to expect overexpression of Bapx1 in certain forms of polydactyly. Developmental Dynamics 235:2483–2492, 2006. © 2006 Wiley‐Liss, Inc.
Synthesis, Structure, and Magnetic Behavior of Two New 1D Polymeric Manganese Azido Complexes
Authors: Abu‐Youssef Morsy A. M. , Escuer Albert , Langer Vratislav 
Published: June 2006

AbstractTwo new MnII one‐dimensional compounds with formulae [Mn(μ‐N3)2(pyzamid)2]n (1) and [Mn2(3‐ampy)4(μ‐N3)2(N3)2(H2O)2]n, (2) (pyzamid = pyrazineamide and 3‐ampy = 3‐aminopyridine) were structurally and magnetically characterized. Compound 1 crystallizes in the monoclinic system, P2/c space group, and polymerizes through double end‐on azido bridges giving 1D chains with the MnII atoms in a MnN6 environment. Compound 2 crystallizes in the triclinic system, P$\bar {1}$ space group, and consists of alternate [Mn(3‐ampy)2(μ‐N3)2(N3)2] and [Mn(3‐ampy)2(μ‐N3)2(H2O)2] octahedrons (MnN6 – MnN4O2 environments), linked by single end‐to‐end azido bridges. Both chains show very uncommon topologies. Attemps to obtain manganese/azido derivatives with the qux = quinoline‐4‐carboxylato anion gave the recently reported compound [Mn(μ‐qux)2(μ‐H2O)]n (3), which consists of a chain with only carboxylato and aqua bridges with the MnII atoms in a MnO6 slightly distorted octahedron. In good agreement with the expected behavior, magnetic susceptibility measurements show weak ferromagnetic interactions for 1, whereas compound 2 exhibits moderate antiferromagnetic coupling.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Chiral Organometallic Catalysts in Confined Nanospaces: Significantly Enhanced Enantioselectivity and Stability
Authors: Song Choong Eui , Kim Dong Hyun , Choi Doo Seoung 
Published: June 2006

AbstractThis microreview presents some selected representative examples which demonstrate that significant improvement in the catalytic performance (increase in catalytic activity, stability and chemo‐ and enantioselectivity) of organometallic chiral catalysts as well as their recycling ability can be achieved by heterogenizing them in the confined spaces of porous or layered support materials. The positive effects of immobilization on the catalytic efficiencies are discussed in terms of the confinement effect and site‐isolation effect, etc., with the aim of understanding the extent to which such effects lead to positive changes in the catalytic properties. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Conformationally Biased Selective Alkylation of trans‐Cyclohexane‐1,2‐bis(sulfonamide) Assisted by Solvent‐Tuned Protecting Groups: Applications to the Synthesis of a Large Optically Active Polyazamacrocycle
Authors: Peña Carmen , Alfonso Ignacio , Gotor Vicente 
Published: June 2006

AbstractThe selective alkylation of (R,R)‐cyclohexane‐1,2‐bis(sulfonamide) with trityl bromoalkyl ethers has been studied in detail. The major formation of either mono‐ or dialkylated compounds clearly depends on the right combination of protecting groups and the reaction solvent. An exhaustive study suggests that this effect can be reasonably explained by the conformational preferences of the monoalkylated compounds, which also depend on the reaction medium, solvophobic effects and weak intramolecular interactions. Structural analysis by NOE measurements showed the presence of folded conformations in solution for all the tested examples. Monte Carlo conformational searches supported this proposal, showing a very good correlation between the fraction of folded species and the selectivity towards monoalkylation. Finally, tuning of the reaction conditions, leading to either extended or folded conformations of the monoalkylated synthetic intermediates, was exploited for the efficient synthesis of a large optically active polyazamacrocycle. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Comparison between Nafion® and a Nafion® Zirconium Phosphate Nano‐Composite in Fuel Cell Applications
Authors: Bauer F. , Willert‐Porada M. 
Published: June 2006

AbstractA comparative investigation of the electrical, mechanical, and chemical behaviour of zirconium phosphate‐Nafion® composite membranes and Nafion® by means of ex‐situ measurements, as well as with fuel cell operation, reveals a slight reduction of ionic conductivity, a significant improvement of mechanical stability, and increased water retention for the composite materials. The overall efficiency at 130 °C is increased during direct methanol fuel cell (DMFC) operation because the reduction in the ionic conductivity is overcompensated for by the decrease in methanol crossover. With H2 as the fuel, the slight reduction in overall efficiency corresponds to the decrease in ionic conductivity. The dimensional stability of the membrane and the membrane electrode assembly (MEA) is significantly improved for operating temperatures above 100 °C. A model for the microstructure‐property relation for PFSA‐Zr(HPO4)2 · n H2O composite membranes is presented, based on the experimental results from membranes with varying filler contents and distributions, obtained through different synthesis routes. It is aimed at the improvement of water distribution in the membrane upon fuel cell operation.
MicroRNA: A new player in stem cells
Authors: Zhang Baohong , Pan Xiaoping , Anderson Todd A. 
Published: June 2006

AbstractmicroRNAs (miRNAs) are an abundant class of endogenous non‐protein‐coding small RNAs, which negatively regulate gene expression at the posttranscriptional level in many developmental and metabolic processes. miRNAs regulate a variety of biological processes, including developmental timing, signal transduction, tissue differentiation and maintenance, disease, and carcinogenesis. Emerging evidence demonstrates that miRNAs also play an essential role in stem cell self‐renewal and differentiation. Some miRNAs are specifically expressed in stem cells, control stem cell self‐renewal, and differentiation through negatively regulating the expression of certain key genes in stem cells. J. Cell. Physiol. 209: 266–269, 2006. © 2006 Wiley‐Liss, Inc.
Synergistic extraction of rare earths(III) from chloride medium with mixtures of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate
Authors: Zhao Junmei , Meng Shulan , Li Deqian 
Published: June 2006

AbstractThe synergistic effect of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 (HPMBP, HA) and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate (DEHEHP, B) in the extraction of rare earths (RE) from chloride solutions has been investigated. Under the experimental conditions used, there was no detectable extraction when DEHEHP was used as a single extractant while the amount of RE(III) extracted by HPMBP alone was also low. But mixtures of the two extractants at a certain ratio had very high extractability for all the RE(III). For example, the synergistic enhancement coefficient was calculated to be 9.35 for Y3+, and taking Yb3+and Y3+as examples, RE3+is extracted as RE(OH)A2.B. The stoichiometry, extraction constants and thermodynamic functions such as Gibbs free energy change ΔG(−17.06 kJ mol−1), enthalpy change ΔH(−35.08 kJ mol−1) and entropy change ΔS(−60.47 J K−1mol−1) for Y3+at 298 K were determined. The separation factors (SF) for adjacent pairs of rare earths were calculated. Studies show that the binary extraction system not only enhances the extraction efficiency of RE(III) but also improves the selectivity, especially between La(III) and the other rare earth elements. Copyright © 2006 Society of Chemical Industry
Estimate of vascular permeability and cerebral blood volume using Gd‐DTPA contrast enhancement and dynamic T2*‐weighted MRI
Authors: Cao Yue , Shen Zhen , Chenevert Thomas L. , Ewing James R. 
Published: June 2006

AbstractPurposeTo develop a numerical approach for estimation of vascular permeability from dynamic T2*‐weighted imaging, a technique routinely used to measure cerebral blood volume (CBV) and flow in gliomas.Materials and MethodsThis study describes a process for estimating both the gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA) transvascular transfer constant and CBV from dynamic T2*‐weighted images. The algorithm was applied to data from the brains of 12 patients with grade IV gliomas. The stability of the method was assessed. Estimates of CBV by this technique were compared to those of the conventional method.ResultsThe algorithm was found to be insensitive to noise and to generate stable voxel‐by‐voxel estimates of permeability and CBV.ConclusionUsing a single imaging acquisition, the three most important vascular properties, CBV, cerebral blood flow (CBF), and permeability, can be estimated. This approach may have potential in clinical evaluation of patients with brain tumor or acute ischemic stroke. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Variable MR findings in ovarian functional hemorrhagic cysts
Authors: Kanso Hassan N. , Hachem Kamal , Aoun Noël J. , Haddad‐Zebouni Soha , Klein‐Tomb Laurence , Atallah David , Buy Jean‐Noël , Ghossain Michel A. 
Published: June 2006

AbstractPurposeTo describe the magnetic resonance (MR) findings in ovarian functional hemorrhagic cysts (FHC).Materials and MethodsA total of 21 patients with 22 FHC, proven by follow‐up ultrasound (US) in 11 women and surgery in 10 women, had US and MR examinations within 24 hours. The study was limited to cysts with obvious an echogenic pattern. All patients had T2‐weighted fast spin echo (FSE), T1‐weighted spin echo (SE), and T1‐weighted SE fat‐suppressed sequences.ResultsFour cysts (18%) were hypointense on T1‐weighted‐images without and with fat suppression, and hyperintense on T2‐weighted‐images. Five cysts (23%) were hypointense on T1‐weighted images without and with fat suppression but heterogenous on T2‐weighted images. Five cysts (23%) were hypointense on T1‐weighted images but showed intermediate signal intensity on T1‐weighted fat suppression images and heterogenous signal intensity on T2‐weighted images. Two cysts (9%) were entirely intermediate on T1‐weighted images. Five cysts (23%) displayed high signal intensity occupying less than 30% of the cystic content on T1‐weighted images and one cyst (5%) displayed high signal intensity occupying more than 30% of the cystic content.ConclusionDespite an obvious echogenic pattern on US, 64% of FHC were hypointense on T1‐weighted images and 18% were also hyperintense on T2‐weighted images. Only 36% demonstrated intermediate or high signal intensity on T1‐weighted images. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Sticking to our guns: social identity as a basis for the maintenance of commitment to faltering organizational projects
Authors: Haslam S. Alexander , Ryan Michelle K. , Postmes Tom , Spears Russell , Jetten Jolanda , Webley Paul 
Published: June 2006

AbstractWhat leads some people to maintain commitment to faltering organizational projects while others abandon them? Building on previous work that has examined the link between social identity and the characteristics of decision‐making associated with groupthink, this paper argues that one key determinant of continued commitment to group projects is the extent to which group members define themselves in terms of a shared social identity rather than as individuals. This hypothesis is tested in two experiments that manipulate social identity salience and monitor attitudinal and financial commitment to an organizational project that encounters increasing difficulties over time. As predicted, in both studies, experimentally induced social identification leads to sustained commitment to the project across three temporal phases, while individuation of participants leads to a loss of faith and reduced financial commitment. These results contribute to theoretical understanding of the important role played by social identity in unfolding patterns of organizational and team commitment. Copyright © 2006 John Wiley & Sons, Ltd.