bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses, Characterization and Catalytic Application of Palladacycles Containing Phosphane or Phosphane Oxide Functionalities
Authors: Peng Kuo‐Fu , Chen Ming‐Tsz , Huang Chi‐An , Chen Chi‐Tien 
Published: April 2008

AbstractThe preparation of ligand precursors PhN=C(CMe2)(NPh)C=N(CH2)2PPh2 (1) and PhN=C(CMe2)(NPh)C=N(CH2)2P(O)Ph2 (2) are described. Treatment of 1 or 2 with 1 mol equiv. Pd(OAc)2 affords orthometallated palladium(II) complexes [PhN=C(CMe2)(N‐η1‐Ph)C=N(CH2)2PPh2]Pd(OAc) (3) as a mononuclear complex or {[PhN=C(CMe2)(N‐η1‐Ph)C=N(CH2)2P(O)Ph2]Pd(OAc)}2 (4) as an acetate‐bridged dinuclear complex, respectively. Reaction of 3 with excess LiCl in methanol affords a mononuclear palladium(II) complex [PhN=C(CMe2)(N‐η1‐Ph)C=N(CH2)2PPh2]PdCl (5). The crystal and molecular structures are reported for compounds 3–5. Application of these novel palladacyclic complexes to the Suzuki and Heck reactions with aryl halide substrates was examined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Formation of Micro/Macroporous Hierarchical Spheres of Titanosilicate Umbite
Authors: Sebastián Víctor , Téllez Carlos , Coronas Joaquín , Santamaría Jesús 
Published: April 2008

AbstractPolycrystalline spheres of up to 2 mm diameter of microporous titanosilicate K2TiSi3O9·H2O with umbite structure (Ti‐umbite) were prepared without the use of organic structuring agents. The spheres, while preserving the inherent microporosity of the umbite type‐material, are organized as hierarchical materials with macropores in the 0.1–1.4‐μm size range. Ti‐umbite spheres were only produced by hydrothermal synthesis under rotation conditions, at 230 °C by using a solution with the following molar composition:0.284 K2O/0.287 Na2O/SiO2/0.095 TiO2(anatase)/30.8 H2O, andit was observed that the synthesis time and the rotation speed of the autoclave influenced the particle size distribution. When the procedure was carried out at 30 rpm and for 48 h, the size of the Ti‐umbite spheres adjusted well to a normal distribution, with a statistical mode of 492 ± 13 μm. Also, under these conditions the amount of unreacted TiO2 anatase, which has a key role in the formation of the Ti‐umbite spheres, was only 14.4 wt.‐%. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Mo‐Catalyzed Cross‐Metathesis Reaction of Propynylferrocene
Authors: Bobula Tomáš , Hudlický Jason , Novák Petr , Gyepes Róbert , Císařová Ivana , Štěpnička Petr , Kotora Martin 
Published: April 2008

AbstractCatalysts formed in situ from [Mo(CO)6] and halophenols in dichloromethane efficiently promote cross metathesis reactions of (prop‐1‐yn‐1‐yl)ferrocene with various functionalized alkynes to give the corresponding alkynylferrocenes with good selectivity and yields. Optimization of the reaction conditions by changing the phenol component has been carried out, revealing a critical influence of the phenol structure on the reaction yield. The structures of selected compounds were determined by single‐crystal X‐ray diffraction, and the results (particularly the crystal packing) were correlated with DFT calculations. In addition, the series of alkynes 4‐XC6H4C≡CFc (Fc = ferrocenyl) differing by the substituent X was studied by electrochemical methods, manifesting a good correlation between the redox potential of the ferrocene/ferrocenium couple and the Hammett σp constants of the remote substituents X. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Guanidine‐Catalyzed Asymmetric Synthesis of 2,2‐Disubstituted Chromane Skeletons by Intramolecular Oxa‐Michael Addition
Authors: Saito Noriko , Ryoda Akemi , Nakanishi Waka , Kumamoto Takuya , Ishikawa Tsutomu 
Published: April 2008

AbstractThe guanidine‐catalyzed 6‐exo‐trig‐type intramolecular asymmetric oxa‐Michael addition of α,β‐unsaturated esters with a 2‐hydroxyaryl moiety at the C‐5 carbon has been examined for the construction of chromane skeletons with a quaternary carbon chiral center. The bulkiness of the alkyl group and the E/Z geometry of the α,β‐unsaturated ester function played important roles in the asymmetric induction and (4S,5S)‐2‐[(R)‐1‐hydroxymethyl‐2‐phenylethylimino]‐1,3‐dimethylimidazolidine (or its enantiomer) carrying aryl pendants at the 4‐ and 5‐positions was found to be the most effective catalyst among 18 chiral guanidines examined. In this way, the Z isomer of the less bulky methyl ester was subjected to the cyclization reaction, affording chiral chromane in up to 83 % yield with 76 % ee. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Preparation of Novel Arrays Silver Nanoparticles Modified Polyrutin Coat‐Paraffin‐Impregnated Graphite Electrode for Tyrosine and Tryptophan's Oxidation
Authors: Jin Guan‐Ping , Peng Xia , Chen Qun‐Zhi 
Published: April 2008

AbstractA novel array silver nanoparticles and Rutin complex film modified paraffin‐impregnated graphite electrode was proposed in this work (denoted as Ag/Rutin/WGE). The characteristics were investigated by the field emission scanning electron microscopy (FE‐SEM), infrared spectra (IR), UV‐visible (UV), X‐ray photoelectron spectroscopy (XPS) and electrochemical techniques. Silver ions were gradually chelated by polyrutin film at 4′‐oxo‐5′‐OH and 5‐OH‐4‐oxo sites accompanying adsorption, then. Silver nanoparticles were highly‐dispersed electrodeposited on polyrutin film. The electrochemical behaviors of tyrosine (Tyr) and tryptophan (Trp) were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The Ag/Rutin/WGE electrode shows overlapping catalysis for the oxidation of Tyr and Trp. The linear response of Tyr and Trp were 0.3–10.0 and 0.7–70.0 μM with detection limit of 0.07 and 0.1 μM in a signal‐to‐noise ratio of 3.
Improved repeatability and matrix‐assisted desorption/ionization – time of flight mass spectrometry compatibility in capillary isoelectric focusing
Authors: Silvertand Linda H. H. , Toraño Javier Sastre , de Jong Gerhardus J. , van Bennekom Wouter P. 
Published: April 2008

AbstractLow repeatability of migration time, peak area, and linearity (pI vs. mobilization time) is a problem often encountered in capillary IEF (cIEF) and is mainly caused by protein precipitation and protein–wall interactions. In order to study the influence of these phenomena, the effect of different classes of additives on repeatability of migration time, peak area and linearity of a mixture of seven model proteins has been investigated. Moreover, the influence of these additives on protein signal suppression in MALDI‐TOF MS has been studied. The optimal ampholyte blend (stabilizes pH gradient) to be used depends on the selected UV detection wavelength. All tested ampholyte blends show a significant and comparable signal suppression in MS. The best detergent (to prevent precipitation and wall interaction) should be determined for each sample individually, but generally polyethylene oxide and zwitterionic detergents show good repeatability for migration time (RSD <4.5%) and peak area (majority <10%). The RSD of R2 is <1.3% for the hydrophilic protein mixture. However, these components cause severe signal suppression in MS. Therefore glucoside detergents should preferably be used for MS coupling. Viscosity‐increasing agents (for hydrodynamic wall coating and to minimize diffusion) in particular cellulose derivatives, give good repeatability for migration times (RSD <4.5% at lower concentrations), peak area (except for high concentration methylcellulose and hydroxyethylcellulose all within 7.5%), and correlation (pI vs. migration time), but severe signal suppression is observed in MALDI‐TOF MS. Overall, cIEF repeatability and linearity can significantly be improved by adding the appropriate components. However, when the system is coupled to a MALDI‐TOF MS, compromises have to be made between high repeatability and linearity on one hand and MS signal intensity on the other.
Development of a low‐flow multiplexed interface for capillary electrophoresis/electrospray ion trap mass spectrometry using sequential spray
Authors: Chen Chao‐Jung , Li Fu‐An , Her Guor‐Rong 
Published: April 2008

AbstractA multiplexed CE‐MS interface using four low‐flow sheath liquid ESI sprayers has been developed. Because of the limited space between the low‐flow sprayers and the entrance aperture of the ESI source, multichannel analysis is difficult using conventional rotating plate approaches. Instead, a multiplexed low‐flow system was achieved by applying an ESI potential sequentially to the four low‐flow sprayers, resulting in only one sprayer being sprayed at any given time. The synchronization of the scan event and the voltage relays was accomplished by using the data acquisition signal from the IT mass spectrometer. This synchronization resulted in the ESI voltage being sequentially applied to each of the four sprayers according to the corresponding scan event. With this design, a four‐fold increase in analytical throughput was achieved. Because of the use of low‐flow interfaces, this multiplexed system has superior sensitivity than a rotating plate design using conventional sheath liquid interfaces. The multiplexed design presented has the potential to be applied to other low‐flow multiplexed systems, such as multiplexed capillary LC and multiplexed CEC.
Development of a quantitative, validated Capillary electrophoresis‐time of flight – mass spectrometry method with integrated high‐confidence analyte identification for metabolomics
Authors: Timischl Birgit , Dettmer Katja , Kaspar Hannelore , Thieme Marian , Oefner Peter J. 
Published: April 2008

AbstractA CE‐MS method was developed and validated for the quantitative analysis of negatively charged metabolites by making use of the high mass accuracy and the quantitation capabilities of a TOF mass analyzer in combination with automated feature extraction and database search. Metabolites of the central carbon metabolism were quantified with an LOD and lower LOQ (LLOQ) of 0.2–2 and 1–4 µM, respectively. The method was used to elucidate metabolic changes in the Escherichia coli deletion mutant PntAB‐UdhA that lacks nicotinamide nucleotide transhydrogenase function, under both stationary and exponential growth conditions. The reproducibility of metabolite extraction and CE‐TOF‐MS analysis ranged from 3.7 to 22.7 and 7.9 to 22.6%, respectively, while the biological variance was 3.4–31.3%. We observed significant differences in metabolite abundance, particularly in the citrate cycle, between wild‐type and mutant E. coli. Overall, more than 600 features were found by automated feature detection, which resulted in ∼150 high‐confidence metabolite identifications. Concomitant analyses with two different GC‐MS methods allowed not only crossvalidation of the quantitative results obtained by the various methods, but also led to a more comprehensive coverage of the E. coli metabolome.
Simultaneous Application of Glucose Oxidases and Peroxidases in Bleaching Processes
Authors: Opwis K. , Knittel D. , Schollmeyer E. , Hoferichter P. , Cordes A. 
Published: April 2008

AbstractPeroxidases (POD) are used in textile decoloration and bleaching processes, but these enzymes are unfortunately inactivated rapidly at high hydrogen peroxide concentrations. A new concept has therefore been developed, which is based on a simultaneous application of glucose oxidase and peroxidase. Starting with glucose as a substrate for glucose oxidase (GOD), hydrogen peroxide was generated in situ. The freshly formed substrate H2O2 was immediately used by the POD oxidizing colored compounds in dyeing baths. For example, 20 mg of the dyestuff Sirius Supra Blue®FGG 200 % could be decolorized using 125 mg glucose which corresponds to 24 mg hydrogen peroxide. These experiments show that the enzyme cascade works in principle in homogeneous decoloration processes. The enzymes were not degraded by the oxidant, because under these conditions the stationary peroxide concentration is nearly zero over the whole reaction time. Moreover, experiments were carried out to check if this combined system with GOD, glucose and POD could be used even in heterogeneous systems such as the textile bleaching of natural cotton fibers. Starting from 55, a significant higher degree of whiteness (according to Berger) up to 66 could be obtained.
Methodology for the development of analytical fragility curves for retrofitted bridges
Authors: Padgett Jamie E. , DesRoches Reginald 
Published: April 2008

AbstractFragility curves for retrofitted bridges indicate the influence of various retrofit measures on the probability of achieving specified levels of damage. This paper presents an analytical methodology for developing fragility curves for classes of retrofitted bridge systems. The approach captures the impact of retrofit on the vulnerability of multiple components, which to date has not been adequately addressed, and results in a comparison of the system fragility before and after the application of different retrofit measures. Details presented include analytical modeling, uncertainty treatment, impact of retrofit on demand models, capacity estimates, and component and system fragility curves. The findings indicate the importance of evaluating the impact of retrofit not only on the targeted response quantity and component vulnerability but also on the overall bridge fragility. As illustrated by the case study of a retrofitted multi‐span continuous (MSC) concrete girder bridge class, a given retrofit measure may have a positive impact on some components, yet no impact or a negative impact on other critical components. Consideration of the fragility based only on individual retrofitted components, without regard for the system, may lead to over‐estimation or under‐estimation of the impact on the bridge fragility. The proposed methodology provides an opportunity to effectively compare the fragility of the MSC concrete bridge retrofit with a range of different retrofit measures. The most effective retrofit in reducing probable damage for a given intensity is a function of the damage state of interest. Copyright © 2008 John Wiley & Sons, Ltd.
Sinusoidal endothelial cells prevent rat stellate cell activation and promote reversion to quiescence
Authors: DeLeve Laurie D. , Wang Xiangdong , Guo Yumei 
Published: April 2008

Abstract

Capillarization precedes hepatic fibrosis. We hypothesize that capillarization of sinusoidal endothelial cells (SEC) is permissive for hepatic stellate cell (HSC) activation and therefore permissive for fibrosis. We examined whether freshly isolated SECs prevent activation of HSCs and promote reversion to quiescence, and whether this effect was lost in capillarization. HSCs were cultured alone or co-cultured with differentiated or capillarized SECs. Results: Co-culture with freshly isolated SECs markedly decreased HSC activation after 3 days in culture, but co-culture with capillarized SEC had no effect. Inhibition of nitric oxide (NO) synthesis abolished SEC suppression of HSC activation. Activated HSCs reverted to quiescence when co-cultured with SEC plus vascular endothelial growth factor (VEGF) (that is, with SECs that maintained differentiation), but co-culture with capillarized SECs did not. Reversion of activated HSCs to quiescence in the presence of SECs plus VEGF was abolished by inhibition of NO synthesis. To establish whether there was indeed reversion, activated and quiescent HSCs were counted before and 3 days after adding freshly isolated SECs plus VEGF to activated HSCs, and proliferation was quantified in quiescent HSCs; the stoichiometry demonstrated reversion.

Conclusion:

Differentiated SECs prevent HSC activation and promote reversion of activated HSCs to quiescence through VEGF-stimulated NO production. Capillarized SECs do not promote HSC quiescence, because of loss of VEGF-stimulated NO production. (Hepatology 2008.)
Levels of ATP in different organic wastes under composting conditions
Authors: Montes Juan Antonio , Sánchez Antoni 
Published: April 2008

AbstractBACKGROUND: The concentration of ATP in selected samples from the composting process of several organic wastes (municipal solid wastes, wastewater sludge, animal by‐products and cow manure) has been determined in order to characterize the aerobic biological activity of such wastes.RESULTS: The values obtained ranged from 0 (in old stable compost from cow manure) to 0.07 µmol ATP g−1 dry matter in thermophilic samples of municipal solid wastes composting. In general, it was found that ATP levels were in agreement with the stage of the composting process (initial stage, thermophilic period and maturation). On the other hand, ATP concentration correlated well (P < 0.05) with the overall respiration activity during a complete composting process of municipal solid waste at full scale.CONCLUSION: ATP concentration can be used to determine the biological activity of organic solid wastes in different stages of their biological treatment and to predict compost stability prior to soil application. Copyright © 2008 Society of Chemical Industry
Lovastatin production by Aspergillus terreus in a two‐staged feeding operation
Authors: Porcel Elisa M Rodríguez , López Jose L Casas , Pérez Jose A Sánchez , Chisti Yusuf 
Published: April 2008

AbstractBACKGROUND: Lovastatin is known to inhibit its own synthesis in the fungus Aspergillus terreus. Therefore, the use of a fermentation strategy that continuously removes some of the lovastatin produced from the bioreactor can enhance its productivity. This paper reports on the effects of dilution rate and the composition of the feed medium on lovastatin production by A. terreus.RESULTS: The feeding strategy consisted of an initial batch/fed‐batch phase and a semi‐continuous culture phase in which the pelleted biomass was retained inside a slurry bubble column. A nitrogen‐free medium was fed at various fixed dilution rates in the semi‐continuous phase. In experiments that were designed to assess the effects of the composition of the medium, the dilution rate was held at 0.42 d−1, but different feed media were used in separate runs. The best two‐staged production strategy was shown to consist of a 96 h batch/fed‐batch phase that used a nutritionally complete medium. This was followed by a semi‐continuous operation using a medium that was free of both nitrogen and carbon sources.CONCLUSION: Semi‐continuous operation enhanced productivity of lovastatin by 315% compared with a conventional batch operation. The optimal dilution rate in semi‐continuous operation was about 0.42 d−1. Copyright © 2008 Society of Chemical Industry
Revisiting Wittgenstein on Köhler and Gestalt psychology
Authors: Benjafield John G. 
Published: April 2008

AbstractIn an article in this journal, Nicholas Pastore rejected Ludwig Wittgenstein's critique of Wolfgang Köhler and Gestalt psychology. Pastore appears not to have appreciated Wittgenstein's argument that Köhler mistook conceptual questions for factual ones. A simi‐lar confusion seems to underlie at least some aspects of contemporary neuroscience. Be that as it may, Wittgenstein has had minimal influence on the research practices of psychologists while Köhler remains influential. This outcome would not have surprised Wittgenstein, who predicted that scientists would not see his work as relevant to theirs. © 2008 Wiley Periodicals, Inc.
Toward a transnational history of the social sciences
Authors: Heilbron Johan , Guilhot Nicolas , Jeanpierre Laurent 
Published: April 2008

AbstractHistorical accounts of the social sciences have too often accepted local or national institu‐tions as a self‐evident framework of analysis, instead of considering them as being embed‐ded in transnational relations of various kinds. Evolving patterns of transnational mobility and exchange cut through the neat distinction between the local, the national, and the inter‐national, and thus represent an essential component in the dynamics of the social sciences, as well as a fruitful perspective for rethinking their historical development. In this pro‐grammatic outline, it is argued that a transnational history of the social sciences may be fruitfully understood on the basis of three general mechanisms, which have structured the transnational flows of people and ideas in decisive ways: (a) the functioning of international scholarly institutions, (b) the transnational mobility of scholars, and (c) the politics of trans‐national exchange of nonacademic institutions. The article subsequently examines and illustrates each of these mechanisms. © 2008 Wiley Periodicals, Inc.
MRI‐compatible manipulator with remote‐center‐of‐motion control
Authors: Hata Nobuhiko , Tokuda Junichi , Hurwitz Shelley , Morikawa Shigehiro 
Published: April 2008

AbstractPurposeTo develop and assess a needle‐guiding manipulator for MRI‐guided therapy that allows a physician to freely select the needle insertion path while maintaining remote center of motion (RCM) at the tumor site.Materials and MethodsThe manipulator consists of a three‐degrees‐of‐freedom (DOF) base stage and passive needle holder with unconstrained two‐DOF rotation. The synergistic control keeps the Virtual RCM at the preplanned target using encoder outputs from the needle holder as input to motorize the base stage.ResultsThe manipulator assists in searching for an optimal needle insertion path which is a complex and time‐consuming task in MRI‐guided ablation therapy for liver tumors. The assessment study showed that accuracy of keeping the virtual RCM to predefined position is 3.0 mm. In a phantom test, the physicians found the needle insertion path faster with than without the manipulator (number of physicians = 3, P = 0.001). However, the alignment time with the virtual RCM was not shorter when imaging time for planning were considered.ConclusionThe study indicated that the robot holds promise as a tool for accurately and interactively selecting the optimal needle insertion path in liver ablation therapy guided by open‐configuration MRI. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
Real‐time fast strain‐encoded magnetic resonance imaging to evaluate regional myocardial function at 3.0 Tesla: Comparison to conventional tagging
Authors: Korosoglou Grigorios , Youssef Amr A. , Bilchick Kenneth C. , Ibrahim El‐Sayed , Lardo Albert C. , Lai Shenghan , Osman Nael F. 
Published: April 2008

AbstractPurposeTo compare the utility of the real‐time technique fast strain‐encoded magnetic resonance imaging (fast‐SENC) for the quantification of regional myocardial function to conventional tagged magnetic resonance imaging (MRI).Materials and MethodsHealthy volunteers (N = 12) and patients with heart failure (N = 7) were examined using tagged MRI and fast‐SENC at 3.0T. Circumferential strain was measured using fast‐SENC in six endo‐ and six subepicardial regions in the basal‐, mid‐, and apical‐septum and the basal‐, mid‐, and apical‐lateral wall from the four‐chamber view. These measurements were plotted to tagging, in corresponding myocardial segments.ResultsPeak systolic strain (Ecc) and early diastolic strain rate (Ecc/second) acquired by fast‐SENC correlated closely to tagged MRI (r = 0.90 for Ecc and r = 0.91 for Ecc/second, P < 0.001 for both). Both fast‐SENC and tagging identified differences in regional systolic and diastolic function between normal myocardium and dysfunctional segments in patients with heart failure (for fast‐SENC: Ecc = −21.7 ± 2.7 in healthy volunteers vs. −12.8 ± 4.2 in hypokinetic vs. 0.6 ± 3.8 in akinetic/dyskinetic segments, P < 0.001 between all; Ecc/second = 104 ± 20/second in healthy volunteers vs. 37 ± 9/second in hypokinetic vs. −16 ± 15/second in akinetic/dyskinetic segments, P < 0.001 between all). Quantitative analysis was more time‐consuming for conventional tagging than for fast‐SENC (time‐spent of 3.8 ± 0.7 minutes vs. 9.5 ± 0.7 minutes per patient, P < 0.001).ConclusionFast‐SENC allows the rapid and accurate quantification of regional myocardial function. The information derived from fast‐SENC during a single heartbeat seems to be superior or equal to that acquired by conventional tagging during several heart cycles and prolonged breathholds. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.