bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cobalt nanoparticles as a novel magnetic resonance contrast agent—relaxivities at 1.5 and 3 Tesla
Authors: Parkes Laura M. , Hodgson Richard , Lu Le T. , Tung Le D. , Robinson Ian , Fernig David G. , Thanh Nguyen T. K. 
Published: August 2008

AbstractTwo samples of polymer‐coated cobalt nanoparticles were synthesized and dispersed in agarose gel and water. The relaxivities r1 and r2 of the two samples were obtained at different temperatures (25, 37 and 40°C) and magnetic field strengths (1.5 and 3 T). The average cobalt core diameters of the two samples were 3.3 and 3.9 nm (measured by transmission electron microscopy); the corresponding average total diameters (cobalt core + polymer coating) were 13 and 28 nm (measured by dynamic light scattering). The larger particles had the higher r1 relaxivity, whilst r2 was similar for the two samples. There was no significant change in r1 or r2 relaxivities with temperature but r1 at 1.5 T was approximately double the value at 3 T. The highest relaxivities were obtained at 1.5 T with values for r1 and r2 of 7.4 and 88 mM−1 s−1, respectively. These values are similar to those reported for iron oxide with larger core size, suggesting the potential of the cobalt nanoparticles for development and future use as a negative contrast agent. Copyright © 2008 John Wiley & Sons, Ltd.
Avoiding spurious modes of time discretized operators in transport problems
Authors: Arruda Natália C. , Almeida R. C. , Silva R. S. , Malta Sandra M. C. 
Published: September 2008

AbstractThe solution of the Crank–Nicolson (CN) method may present spurious modes, which mostly happens in systems with an initial singularity. In this work, we analyze the onset of spurious oscillations for the CN method for large time steps. This analysis is performed on the general one‐dimensional linear advection–diffusion–reaction transport equation with initial singularity that models a broad range of mass transfer phenomena in natural and engineering sciences. The discrete problem is obtained using a stable finite element method in space and the generalized trapezoidal family of methods in time. Depending on the range of parameters, either the Galerkin or the streamline upwind Petrov–Galerkin methods are used to guarantee stability in space. We derive a stability analysis of the fully discrete method and investigate the techniques proposed in the literature to damp oscillations. We propose a new threshold of time oscillations to overcome the spurious modes, which is also extended to deal with nonlinear problems. Copyright © 2008 John Wiley & Sons, Ltd.
Study of the Photochemical Properties and Conical Intersections of [2,2′‐Bipyridyl]‐3‐amine‐3′‐ol
Authors: Ortiz‐Sánchez Juan Manuel , Gelabert Ricard , Moreno Miquel , Lluch José M. 
Published: August 2008

AbstractThe two isoelectronic bipyridyl derivatives [2,2′‐bipyridyl]‐3,3′‐diamine and [2,2′‐bipyridyl]‐3,3′‐diol are experimentally known to undergo very different excited‐state double‐proton‐transfer processes, which result in fluorescence quantum yields that differ by four orders of magnitude. In a previous study, these differences were explained from a theoretical point of view, because of topographical features in the potential energy surface and the presence of conical intersections (CIs). Here, we analyze the photochemical properties of a new molecule, [2,2′‐bipyridyl]‐3‐amine‐3′‐ol [BP(OH)(NH2)], which is, in fact, a hybrid of the former two. Our density functional theory (DFT), time‐dependent DFT (TDDFT), and complete active space self‐consistent field (CASSCF) calculations indicate that the double‐proton‐transfer process in the ground and first singlet π→π* excited state in BP(OH)(NH2) presents features that are between those of their “parents”. The presence of two CIs and the role they may play in the actual photochemistry of BP(OH)(NH2) and other bipyridyl derivatives are also discussed.
Dynamics of Supramolecular Association Monitored by Fluorescence Correlation Spectroscopy
Authors: Al‐Soufi Wajih , Reija Belén , Felekyan Suren , Seidel Claus A. M. , Novo Mercedes 
Published: August 2008

AbstractSupramolecular binding is a key process in many biological systems and in newly developed supramolecular assemblies. Most of the scientific work on these systems is focused on their structural properties and on the thermodynamics of the association process. However, the underlying dynamics are usually much less known, in spite of the great importance they have during the binding process in these highly dynamic systems. Understanding supramolecular binding in biological systems and controlling the functionality of new synthetic supramolecular systems can only be achieved through knowledge of the structure–dynamics relationship. There is a strong need for suitable techniques which cover the typically wide time interval of the association dynamics and which do not need a perturbation of the system. We briefly review high‐resolution fluorescence correlation spectroscopy (FCS) as a technique to monitor supramolecular dynamics and to give information on how structure determines the dynamics of host–guest association. The comparison of hosts and guests with different structures shows that geometrical and orientational requirements determine the association rate constant, whereas the dissociation is defined by the strength of specific interactions. As model hosts cyclodextrins and micelles are studied.
Reciprocity between the cerebellum and the cerebral cortex: Nonlinear dynamics in microscopic modules for generating voluntary motor commands
Authors: Wang Jun , Dam Gregory , Yildirim Sule , Rand William , Wilensky Uri , Houk James C. 
Published: September 2008

AbstractThe cerebellum and basal ganglia are reciprocally connected with the cerebral cortex, forming many loops that function as distributed processing modules. Here we present a detailed model of one microscopic loop between the motor cortex and the cerebellum, and we show how small arrays of these microscopic loops (CB modules) can be used to generate biologically plausible motor commands for controlling movement. A fundamental feature of CB modules is the presence of positive feedback loops between the cerebellar nucleus and the motor cortex. We use nonlinear dynamics to model one microscopic loop and to investigate its bistable properties. Simulations demonstrate an ability to program a motor command well in advance of command generation and an ability to vary command duration. However, control of command intensity is minimal, which could interfere with the control of movement velocity. To assess these hypotheses, we use a minimal nonlinear model of the neuromuscular (NM) system that translates motor commands into actual movements. Simulations of the combined CB‐NM modular model indicate that movement duration is readily controlled, whereas velocity is poorly controlled. We then explore how an array of eight CB‐NM modules can be used to control the direction and endpoint of a planar movement. In actuality, thousands of such microscopic loops function together as an array of adjustable pattern generators for programming and regulating the composite motor commands that control limb movements. We discuss the biological plausibility and limitations of the model. We also discuss ways in which an agent‐based representation can take advantage of the modularity in order to model this complex system. © 2008 Wiley Periodicals, Inc. Complexity, 2008
An investigation of synchrony in transport networks
Authors: Kincaid Rex K. , Alexandrov Natalia , Holroyd Michael J. 
Published: September 2008

AbstractThe cumulative degree distributions of transport networks, such as air transportation networks and respiratory neuronal networks, follow power laws. The significance of power laws with respect to other network performance measures, such as throughput and synchronization, remains an open question. Evolving methods for the analysis and design of air transportation networks must be able to address network performance in the face of increasing demands and the need to contain and control local network disturbances, such as congestion. Toward this end, we investigate functional relationships that govern the performance of transport networks; for example, the links between the first nontrivial eigenvalue, λ2, of a network's Laplacian matrix—a quantitative measure of network synchronizability—and other global network parameters. In particular, among networks with a fixed degree distribution and fixed network assortativity (a measure of a network's preference to attach nodes based on a similarity or difference), those with small λ2 are shown to be poor synchronizers, to have much longer shortest paths and to have greater clustering in comparison to those with large λ2. A simulation of a respiratory network adds data to our investigation. This study is a beginning step in developing metrics and design variables for the analysis and active design of air transport networks. © 2008 Wiley Periodicals, Inc. Complexity, 2009
A study of the effects of acarbose on glucose metabolism in patients predisposed to developing diabetes: the Dutch acarbose intervention study in persons with impaired glucose tolerance (DAISI)
Authors: Nijpels G. , Boorsma W. , Dekker J. M. , Kostense P. J. , Bouter L. M. , Heine R. J. 
Published: August 2008

AbstractBackgroundWe hypothesized that acarbose would delay conversion from impaired glucose tolerance (IGT) to type 2 diabetes by alleviating postprandial hyperglycaemia. Our study's main objective was to investigate the effect of acarbose in IGT‐persons on their 2‐h plasma glucose level and beta‐cell function.Subjects and MethodsThe study included a random sample of 45–70‐year‐old residents of Hoorn, Netherlands, with mean fasting plasma glucose < 7.8 mmol/L and mean 2‐h plasma glucose of 8.6–11.1 mmol/L (measured by two successive oral glucose tolerance tests). After a qualification period, participants were randomized to acarbose treatment or placebo. Insulin secretion and insulin sensitivity were measured by hyperglycaemic clamp. After a 3‐year treatment, analyses were performed of both the intention‐to‐treat and the per‐protocol groups.ResultsOf the 12 093 residents who received postal invitations, 118 participants were randomized. The mean difference of the post‐load plasma glucose after 3 years, was − 1.16 mmol/L (95% CI: − 2.03; − 0.17). The absolute risk reduction for diabetes was 6% (95% CI: − 9; 21). No effect was seen on insulin secretion and insulin sensitivity.ConclusionsIn patients with IGT, treatment with acarbose was associated with beneficial effects on 2‐h plasma glucose levels but not with improvement of beta‐cell function. Copyright © 2008 John Wiley & Sons, Ltd.
Monocyclopentadienyl Phenoxido–Amino and Phenoxido–Amido Titanium Complexes: Synthesis, Characterisation, and Reactivity of Asymmetric Metal Centre Derivatives
Authors: Alesso Giuseppe , Sanz Martial , Mosquera Marta E. G. , Cuenca Tomás 
Published: August 2008

AbstractReduction of phenol–imine derivatives R′N=CH(3,5‐R2C6H2‐2‐OH) (R = tBu; R′ = C6H5 1a, p‐MeC6H4 1b, Cy 1c, tBu 1d, 2,6‐Me2C6H3 1e; R = H; R′ = p‐MeC6H4 1f; Cy = cyclohexyl) with MBH4 (M = Li, Na) or AlLiH4 in ethyl ether or thf at room temperature affords the phenol–amine compounds R′NHCH2(3,5‐R2C6H2‐2‐OH) 2a–c and 2e,f. The N‐R‐[2,4‐di‐tert‐butyl]benzo‐1‐oxa‐3‐azine species (R = tBu 2d1, 2,6‐Me2C6H3 2e1) are obtained by Mannich reaction of 2,4‐di‐tert‐butylphenol with RNH2 in refluxing methanol. Intermediate 2d1 is converted in ethanol at room temperature into N‐tert‐butyl[2‐hydroxy‐3,5‐di‐tert‐butyl]benzylamine (2d), whereas 2e is not obtained from 2e1 by using this procedure.N‐alkyl,N‐tert‐butyl[2‐hydroxy‐3,5‐di‐tert‐butyl]benzylaminecompounds tBuN(R)CH2(3,5‐tBu2C6H2‐2‐OH) (R = Me 2g, Et 2h, nPr 2i, CH2Ph 2j) are also prepared by the appropriate synthetic method. Treatment of 2a–c with 1 equiv. of TiCpCl3 in the presence of 2.5 equiv. of NEt3 in hexane at room temperature gives the monocyclopentadienyl phenoxido–amido monochloride complexes TiCp[R′NCH2(3,5‐tBu2C6H2‐2‐O)]Cl (R′ = C6H5 3a, R′ = p‐MeC6H4 3b, R′ = Cy 3c). The analogous complex Ti(η5‐C5H4SiMe2Cl)[C6H5NCH2(3,5‐tBu2C6H2‐2‐O)]Cl (4a) results from the reaction of 2a with Ti(η5‐C5H4SiMe2Cl)Cl3. Nevertheless, 2d reacts with TiCpCl3 in hexane in the presence of NEt3 at room temperature yielding the monocyclopentadienyl phenoxido dichloride compound TiCp[tBuNHCH2(3,5‐tBu2C6H2‐2‐O)]Cl2 (5), whereas in ethyl ether and in the absence of NEt3 adduct 5·HCl is obtained, which is further converted into TiCp[tBuNCH2(3,5‐tBu2C6H2‐2‐O)]Cl (3d) by addition of a NEt3/ethyl ether solution. The reaction of TiCpCl3 with 2a in the presence of 2.5 equiv. of NEt3 in a polar solvent (thf, CH2Cl2 or toluene) at room temperature affords TiCp[Ph(H)NCH2(3,5‐tBu2C6H2‐2‐O)]Cl (6a) as a mixture of two stereoisomers. All the reported compounds were characterised by the usual analytical and spectroscopic methods and the molecular structures of 2a, 2d, 2e and 3d were determined by X‐ray diffraction analysis from suitable single crystals. Preliminary studies of catalytic activity for ethylene polymerisation by using solid methylaluminoxane as cocatalyst were performed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Phosphotungstic Acid Catalyzed Direct Benzylation of β‐Dicarbonyl Compounds
Authors: Wang Guan‐Wu , Shen Ye‐Bing , Wu Xue‐Liang 
Published: September 2008

Abstract12‐Phosphotungstic acid was used as an efficient, ecofriendly, and air‐ and moisture‐stable catalyst to promote the direct substitution of the hydroxy group of benzylic and allylic alcohols with various β‐dicarbonyl compounds. This powerful protocol for carbon–carbon bond‐forming reactions provides monoalkylated dicarbonyl compounds in high yields with great efficiency.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
WO3/70 % TBHP/Aqueous NaOH: An Efficient Catalytic Combination for the Selective Oxidation of Methylarenes and Alkyl Aryl Ketones to Benzoic Acids
Authors: Shaikh Tanveer Mahammad Ali , Sudalai Arumugam 
Published: September 2008

AbstractA new solvent‐free, reusable catalytic combination consisting of WO3/70 % TBHP/aqueous NaOH has been described for the direct oxidation of methylarenes and acetophenones to the corresponding benzoic acids in high yields. Alkylarenes are oxidized to the corresponding aromatic ketones or benzylic alcohols depending upon whether NaOH is used or not.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Fabrication, Characterization, and Application of ‘Sandwich‐Type’ Electrode Based on Single‐Walled Carbon Nanotubes and Room Temperature Ionic Liquid
Authors: Zhang Xuzhi , Liu Shufeng , Jiao Kui , Hu Yuwei 
Published: September 2008

AbstractThe much‐enhanced electrochemical responses of potassium ferricyanide and methylene blue (MB) were firstly explored at the glassy carbon electrode modified with single‐walled carbon nanotubes (SWNT/GCE), indicating the distinct electrochemical activity of SWNTs towards electroactive molecules. A hydrophobic room temperature ionic liquid (RTIL), 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6), was used as electrode modification material, which presented wide electrochemical windows, proton permeation and selective extraction ability. In consideration with the advantages of SWNTs and RTIL in detecting target molecules (TMs), a novel strategy of ‘sandwich–type’ electrode was established with TMs confined by RTIL between the SWNT/GCE and the RTIL membrane. The strategy was used for electrochemical detection of ascorbic acid (AA) and dopamine (DA), and detection limits of 400 and 80 fmol could be obtained, respectively. The selective detection of DA in the presence of high amount of AA could also be realized. This protocol presented many attractive advantages towards voltammetric detection of TMs, such as low sample demand, low cost, high sensitivity, and good stability.
Voltammetric Investigation of Zinc Release from Metallothioneins Modulated by the Glutathione Redox Couple and Separated with a Porous Membrane
Authors: Liu Lin , Yang Julei , Xia Ning , Wang Jianxiu , Zhou Feimeng 
Published: August 2008

AbstractGlutathione (GSH), in addition to serving as a redox buffer in cellular environment, has been suggested as a modulator in metal regulation and homeostasis by metallothioneins (MTs). The interactions of MTs with both GSH and its oxidized form GSSG have been shown to govern the direction of metal transfer. Common methods for the determination of zinc release from MTs modulated by GSH/GSSG either involve radioactive species or enzymes or are labor‐intensive. In this study, upon separation of Zn2+ from the reaction mixture of MTs and GSH with a centrifugal filter membrane, differential pulse voltammetry (DPV) was used for the Zn2+ quantification. The same approach is extended to the studies of metal transfer between Zn7MT with a GSH/GSSG mixture and that between Zn7MT with GSSG. The concomitant conversion between the free thiol and disulfide bonds was confirmed with UV‐vis spectrophotometry. The results demonstrate that GSSG, GSH, and the GSH/GSSG mixture all modulate zinc release from Zn7MT. The percentage of zinc release increases in the order of GSH, GSSG, and the GSH/GSSG mixture. The new approach is demonstrated to be well suited for investigation of redox regulation of MT and its reaction with zinc‐containing enzymes.
Deutsche Floren: Der Weg vom Latein zum Deutsch, von Linné zum Natürlichen System
Authors: Wagenitz G. 
Published: August 2008

AbstractDie erste deutsche Flora ist die Sylva Hercynia (Thal 1588), sie ist auch die erste echte Flora der Welt. Bei ihr und den folgenden ist der Text in Latein und die Namen sind sogenannte Phrasen in alphabetischer Anordnung. In der zweiten Hälfte des 18. Jahrhunderts erscheinen die ersten deutsch geschriebenen Floren, die erste ist die Flora von Danzig von Reyger (1768). Die alphabetische Reihenfolge der Namen wurde zuerst durch Knauth (1687) aufgegeben, der das System von Ray benutzte. Ab 1761 wurde das Sexualsystem von Linné für die Anordnung in Floren zum Standard, es hielt sich bis in die Mitte des 19. Jahrhunderts. Etwa ab 1825 traten in Floren Natürliche Systeme auf, die auf Jussieu (1789) und später auf Koch (1836–1838) basierten. In derselben Zeit wurden Bestimmungsschlüssel ein typischer Bestandteil der Floren. Sie fehlen allerdings häufig in ausgesprochenen Lokalfloren. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Palaeokarpologische Nachweise von neuen Arten aus Reliktfamilien im europäischen Tertiär
Authors: Mai Dieter H. 
Published: August 2008

AbstractEs werden einige Arten der Gattungen Brasenia Schreb. (Fam. Cabombaceae A.Rich.), Datisca L. (Fam. Datiscaceae R.Br.), Halophila Thouars (Fam. Halophilaceae J.Agardh) und Stemona Lour. (Fam. Stemonaceae Engl.) nach karpologischen Funden beschrieben. Neu ist die Art Brasenia ceciliensis Mai, sp. nova. Neu kombiniert werden die Arten Datisca gratioloides (Martinetto) Mai, comb. nova, Halophila tenera (Mai) Mai, comb. nova und Stemona germanica (Mai) Mai, comb. nova. Alle Funde sind von vegetationsgeschichtlicher und paläobiologischer Bedeutung. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fossil fruits of Salsola L. s.l. and Halanthium K.Koch (Chenopodiaceae) from Lower Pleistocene lacustrine sediments in Armenia
Authors: Akopian Janna , Gabrielyan Ivan , Freitag Helmut 
Published: August 2008

AbstractFor the first time imprints of fossil fruits of Salsola L. s.l. and Halanthium K.Koch (Chenopodiaceae, Salsoloideae,) are reported from the territory of Armenia, the latter being the first fossil record of the Southwest Asian genus worldwide. They were collected from fluvio‐lacustrine diatomite layers of the Lower Pleistocene (Sisian series) in the upper‐middle Vorotan river valley recently dated at 1.4–0.935 my (Early Pleistocene). The fossils are described, figured and compared with recent relatives. Due to poor preservation, the identity of the Salsola fruit cannot be specified but the similar genus Kochia can be excluded. The Halanthium fruit seems to differ from those of extant species. Both are also discussed in the context of the very poor fossil Salsoloideae record and of the actual and lower Pleistocene vegetation and environment. The findings of truly semidesert species underline the presence of open landscapes and extremely semiarid to arid conditions. However, stratigraphically more refined analyses are needed to draw conclusions about the former vegetation and the duration of arid periods because most macrofossils reported from the same strata indicate semiarid and even humid environments. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Use of combined molecular biomarkers for prediction of clinical outcomes in locally advanced tonsillar cancers treated with chemoradiotherapy alone
Authors: Chung Yih‐Lin , Lee Ming‐Yuan , Horng Cheng‐Fang , Jian James Jer‐Ming , Cheng Skye Hongiun , Tsai Stella Y. , Hsieh Cheng‐I , Yen Lawrence K. , Lin Ching‐Yuan 
Published: September 2008

AbstractBackground.Environmental exposures to tobacco, alcohol, human papillomavirus (HPV) and/or Epstein‐Barr virus (EBV), all of which can perturb multiple cell cycle proteins or tumor suppressors, have been implicated in the pathogenesis of different subsets of head and neck cancers. The aim of this study was to investigate to which extent the virus infection by itself, and/or the altered cell cycle proteins, contributes to prognosis in locally advanced tonsillar squamous cell carcinomas (TSCCs) treated with concurrent chemoradiotherapy (CCRT) alone.Methods.Serial tumor tissue arrays from archival samples were tested for the presence of HPV genome integration or EBV episome by means of DNA sequencing, real‐time polymerase chain reaction (PCR), and in situ hybridization. Alterations of cell cycle proteins (p53, pRb, and p21) were evaluated by immunohistochemical staining. The association of viral presence with altered cell cycle proteins was correlated to clinical outcomes.Results.Of the 46 patients with the same T2N2bM0 stage IVA among consecutive patients with TSCC, 23 (50%) had integrated HPV DNA and only 1 (2%) had EBV episome. The HPV types detected were almost all HPV‐16. A reduced expression pattern of p53, pRb, and p21 was noted in HPV‐positive tumors, and the incremental number of alterations in the 3 proteins was significantly associated with HPV‐negative tumors. The presence or absence of HPV together with the number of altered expression of the 3 cell cycle markers resulted in further identification of 4 biologically and clinically distinct subgroups with different outcomes after CCRT.Conclusions.Use of combined biomarkers of oncogenic HPV and tumor suppressors of p53, pRb, and p21 in advanced TSCC provides prognostic molecular classification superior to the TNM stage system and identifies low‐risk patients for organ preservation by CCRT alone and high‐risk patients who might benefit from planned tonsillectomy and neck dissection before or after CCRT. © 2008 Wiley Periodicals, Inc. Head Neck, 2009