bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancement of Hydrolysis through the Formation of Mixed Hetero‐Metal Species: Dioxouranium(VI) – Cadmium(II) Mixtures
Authors: Crea Francesco , Milea Demetrio , Sammartano Silvio 
Published: October 2005

AbstractIn order to continue the investigation on the formation of hetero‐metal polynuclear hydrolytic species, in this paper we report some results (at I = 0.16 mol L−1 in NaNO3, at t = 25 °C by potentiometry, ISE‐H+, glass electrode) on the hydrolysis of several mixtures (in different ratios) of the dioxouranium(VI) and cadmium(II) cations. The same experimental and calculation procedure of previously investigated systems was followed, and all measurements were performed by two different operators, using completely independent instruments and reagents. Many different speciation models were considered in the calculations, and a simple statistical analysis of obtained results was proposed too. UO22+ and Cd2+ form two heterometal polynuclear hydrolytic species, namely UO2Cd(OH)3+ and (UO2)2Cd(OH)42+, with logβpqr = −3.25 ± 0.25 and ‐13.75 ± 0.10, respectively. The formation of heterometal hydrolytic species is thermodynamically favored with respect to the homo‐metal ones, and causes an enhancement of the percentage of hydrolyzed metal cations; comparisons with previously studied systems reveal that the hydrolytic behavior of UO22+ / Cd2+ mixtures is more similar to that observed for UO22+ / Cu2+ than for UO22+ / (C2H5)2Sn2+, and the tendency to form hetero polynuclear hydrolytic species with dioxouranium(VI) by other cations follows the trend (C2H5)2Sn2+ > Cu2+ ≥ Cd2+.
Water Quality of Two Glacial Alpine Italian Lakes
Authors: Zelano Vincenzo , Zambrotta Maria , Defilippi Albino , Torazzo Annamaria 
Published: October 2005

AbstractThe purpose of this study was to characterize, in a period of one year, two glacial lakes, Alice and Meugliano, located in an alpine reservoir on the basis of physical and chemical features. The two lakes show two periods of mixing: one in the spring and one in the autumn, so can be classified as dimictic lakes 1. They are characterized by pH, alkalinity, low conductivity and and quite dilute ionic concentrations. With regard to nutrients, most nitrogen occurred in the nitric form in the superficial layers. During the period of thermal stratification, in the anoxic layer NO3− decreases and NH4+ increases, confirming the activity of the anaerobic denitrificant bacteria. Total and soluble phosphorus levels show homogeneity during the cold period at different depths, while with stratification concentrations increase in the hypolimnium and metalimnium. In both lakes there is an inverse correlation between transparency and chlorophyll a. To evaluate the trophic state the conventional criteria of Nurnberg 2 and four lake trophic indices (TSIs) are used 3,4. Both evaluations suggest that the two lakes are eutrophic, with worse conditions in Alice. Deviations of the trophic states, based on the relation between TSIs 5,6, indicate that factors other than phosphorous limit the algal biomass, and that nonalgal particles influence light attenuation.
Molecularly Imprinted Polymer for Monocrotophos and its Binding Characteristics for Organophosphorus Pesticides
Authors: Zhu Xiaolan , Yang Jun , Su Qingde , Cai Jibao , Gao Yun 
Published: October 2005

AbstractIn this study, molecular imprinting was used to develop a method based on noncovalent interaction for the synthesis of a monocrotophos‐specific polymer. The selective binding characteristics of the template polymer were evaluated by 1H NMR study. The result was consistent with the existence of multi‐molecular complexes formed by hydrogen‐bonding interactions. Batch rebinding studies in acetonitrile were undertaken to quantitatively evaluate the affinity of the polymer for monocrotophos. The experimental binding isotherms were fitted to the Freundlich isotherm and the total number of binding sites of the polymer can be calculated to be 4.046μmolg−1. The induced affinity and selectivity by imprinting were examined chromatographically. The polymer gave more than 15 times longer retention for monocrotophos than the nonimprinted polymer with the same chemical composition. Other organophosphorus pesticides under study were eluted close to the void volume on the polymer column.
A Simple and Rapid Spectrophotometric Method for Determination of Ultra Trace Amounts of Thallium(III) with 4‐(4′‐N,N‐Dimethylaminophenyl) Urazole as a New Reagent
Authors: Rezaei Behzad , Mallakpour Shadpour , Khalili Honieh , Rafiee Zahra 
Published: October 2005

AbstractA simple and selective spectrophotometric method is proposed for the determination of ultra trace amounts of Tl(III). The reported method is based on the oxidation of 4‐(4′‐N,N‐dimethylaminophenyl)urazole (DAPU) to the corresponding triazolinedione (TAD) by Tl(III) at pH 4.0. The reaction was monitored spectrophotometrically by measuring the increasing color of TAD compound at 514 nm by the fixed‐time method. At a given time of 2.0 min at 30 °C, the working range of calibration was 5.0 × 10−8 ‐ 2.0 × 10−5 M Tl(III) and detection limit of 5.0 × 10−8 M was obtained. The influences of pH, reagent concentration, ionic strength and temperature were studied. The effect of diverse ions on the determination of Tl(III) by the proposed method was also investigated. Thallium in real samples was determined by this method, with satisfactory results.
Preclinical Huntington's disease: Compensatory brain responses during learning
Authors: Feigin Andrew , Ghilardi Maria‐Felice , Huang Chaorui , Ma Yilong , Carbon Maren , Guttman Mark , Paulsen Jane S. , Ghez Claude P. , Eidelberg David 
Published: October 2005

AbstractMotor sequence learning is abnormal in presymptomatic Huntington's disease (p‐HD). The neural substrates underlying this early manifestation of HD are poorly understood. To study the mechanism of this cognitive abnormality in p‐HD, we used positron emission tomography to record brain activity during motor sequence learning in these subjects. Eleven p‐HD subjects (age, 45.8 ± 11.0 years; CAG repeat length, 41.6 ± 1.8) and 11 age‐matched control subjects (age, 45.3 ± 13.4 years) underwent H215O positron emission tomography while performing a set of kinematically controlled motor sequence learning and execution tasks. Differences in regional brain activation responses between groups and conditions were assessed. In addition, we identified discrete regions in which learning‐related activity correlated with performance. We found that sequence learning was impaired in p‐HD subjects despite normal motor performance. In p‐HD, activation responses during learning were abnormally increased in the left mediodorsal thalamus and orbitofrontal cortex (OFC; BA 11/47). Impaired learning performance in these subjects was associated with increased activation responses in the precuneus (BA 18/31). These data suggest that enhanced activation of thalamocortical pathways during motor learning can compensate for caudate degeneration in p‐HD. Nonetheless, this mechanism may not be sufficient to sustain a normal level of task performance, even during the presymptomatic stage of the disease. Ann Neurol 2006
Noradrenergic modulation of space exploration in visual neglect
Authors: Malhotra Paresh A. , Parton Andrew D. , Greenwood Richard , Husain Masud 
Published: October 2005

AbstractVisual neglect after stroke is often associated with a failure to explore contralesional space. Here, we show that guanfacine, a noradrenergic agonist that modulates dorsolateral prefrontal cortex, improves leftward space exploration in selected right‐hemisphere patients with neglect. The positive effects of guanfacine were associated with extended ability to maintain attention on task. The results suggest that neuropharmacological targeting of intact frontal areas might be one way to enhance cognitive function after damage to posterior brain regions in selected individuals. Ann Neurol 2005
Metallische Schmelzen – Reaktionsmedien zur Präparation intermetallischer Verbindungen
Authors: Kanatzidis Mercouri G. , Pöttgen Rainer , Jeitschko Wolfgang 
Published: October 2005

AbstractZiel dieses Aufsatzes ist es, die Vorzüge von flüssigen Metallen als Lösungsmittel bei der Synthese intermetallischer und ähnlich zusammengesetzter Verbindungen aufzuzeigen. Eine Vielzahl neuer Phasen mit zum Teil ungewöhnlichen Zusammensetzungen wurde in den letzten Jahren auf diese Weise erstmals hergestellt. Nach einem kurzen historischen Überblick werden die vorteilhaften Eigenschaften der eingesetzten Metallschmelzen (Flussmittel, Flux) für die Synthese eines breiten Spektrums von Verbindungen besprochen.
Conformational behavior of temporin A and temporin L in aqueous solution: A computational/experimental study
Authors: D'Abramo M. , Rinaldi A. C. , Bozzi A. , Amadei A. , Mignogna G. , Di Nola A. , Aschi M. 
Published: October 2005

AbstractMolecular dynamics (MD) simulations and circular dichroism (CD) experiments were carried out on aqueous temporin A and L, two short peptides belonging to an interesting class of natural substances known to be active mainly against Gram‐positive/negative bacteria and fungi. Experimental results indicate the higher propensity of temporin L, with respect to temporin A, in forming α‐helical structures. These results were revisited by long‐timescale MD simulations, in which their α‐helical propensity was investigated in the absence of trifluoroethanol. Results clearly show the higher stability of α‐helix conformations in temporin L; moreover, an interestingly strong mechanical analogy emerges since both temporins show the same residue interval (from 7 to 10) as the most energetically accessible for α‐helix formation. Such studies provide some intriguing structural and mechanical evidence that may help in better understanding and rationalizing the conformational behaviour of temporins in water solution and, ultimately, the inner principles of their microbial targets selectivity and mechanism of action at the level of cell membranes. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 215–224, 2006This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Numerical Simulation of the Effect of Solvent Viscosity on the Motions of a β‐Peptide Heptamer
Authors: Gee Peter J. , van Gunsteren Wilfred F. 
Published: October 2005

AbstractThis report examines the effect of a decrease in solvent viscosity on the simulated folding behaviour of a β‐peptide heptamer in methanol. Simulations of the molecular dynamics of the heptamer H‐β3‐HVal‐β3‐HAla‐β3‐HLeu‐(S,S)‐β3‐HAla(αMe)‐β3‐HVal‐β3‐HAla‐β3‐HLeu‐OH in methanol, with an explicit representation of the methanol molecules, were performed for 80 ns at various solvent viscosities. The simulations indicate that at a solvent viscosity of one third of that of methanol, only the dynamic aspects of the folding process are altered, and that the rate of folding is increased. At a viscosity of one tenth of that of methanol, insufficient statistics are obtained within the 80 ns period. We suggest that 80 ns is an insufficient time to reach conformational equilibrium at very low viscosity because the dependence of the folding rate of a β‐peptide on solvent viscosity has two regimes; a result that was observed in another computational study for α‐peptides.
Controlled Hydrothermal Synthesis and Structural Characterization of a Nickel Selenide Series
Authors: Zhuang Zhongbin , Peng Qing , Zhuang Jing , Wang Xun , Li Yadong 
Published: October 2005

AbstractA series of nickel selenides (NiSe2 microcrystals, Ni1−xSe and Ni3Se2 microspheres) has been successfully synthesized through a convenient, low‐temperature hydrothermal method. A good nucleation and growth environment has been created by forming a uniform and transparent solution reaction system. The compositions (including the x value of Ni1−xSe), phase structures, as well as the morphologies of nickel selenides, can be controlled by adjusting the Ni/Se ratio of the raw materials, the pH, the reaction temperatures and times, and so forth. The newly produced Se microspheres in the system have been used as both reactant and in situ template to the Ni1−xSe microspheres. It is found that Ni1−xSe microspheres act as the intermediate precursor during the formation of Ni3Se2 microspheres. Under certain conditions, hexagonal NiSe microspheres can be converted into rhombohedral NiSe nanowires in solution. The formation mechanisms of a series of nickel selenides has been investigated in detail by means of X‐ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. This work has provided a general, simple, and effective method to control the composition, phase structure, and morphology of metal selenides in aqueous solution, which will be important for inorganic synthesis methodology and further applications of selenides.
DFT‐HSAB Prediction of Regioselectivity in 1,3‐Dipolar Cycloadditions: Behavior of (4‐Substituted)benzonitrile Oxides towards Methyl Propiolate
Authors: Ponti Alessandro , Molteni Giorgio 
Published: October 2005

AbstractThe regioselectivity of 1,3‐dipolar cycloadditions between (4‐substituted)benzonitrile oxides and methyl propiolate cannot be rationalized on the basis of the electron demand of the reactants or frontier molecular‐orbital theory. To this problem, we have applied a quantitative formulation of the hard–soft acid–base principle developed within the density functional theory. Global and local reactivity indices were computed at B3LYP/6‐311+G(d,p) level. The details of charge transfer upon the reactive encounter have been elucidated, and the computed regioselectivity has been shown to be in good agreement with experimental data.
Spiral galaxies as enantiomers: Chirality, an underlying feature in chemistry and astrophysics
Authors: Capozziello Salvatore , Lattanzi Alessandra 
Published: October 2005

AbstractSpiral galaxies are axisymmetric objects showing 2D chirality when projected onto a plane. Features in common with tetrahedral molecules are pointed out, in particular the existence of a preferred chiral modality for genetic galaxies as in amino acids and sugars. Environmental effects can influence the intrinsic chirality of originally isolated stellar systems so that a progressive loss of chirality is recognized in the Hubble morphological sequence of galaxies. © 2005 Wiley‐Liss, Inc. Chirality
σ–π Energy Separation in Homodesmotic Reactions
Authors: Hohlneicher Georg , Packschies Lars , Weber Johannes 
Published: October 2005

AbstractA well‐established quantity for specifying the aromaticity or antiaromaticity of cyclic conjugated molecules is the so‐called aromatic stabilization energy (ASE), which can be derived—either experimentally or theoretically—from appropriate homodesmotic reactions. To gain further insight into the origin of aromaticity, several schemes have been devised to partition ASE into nuclear and electronic as well as σ and π contributions, some of which have resulted in contradictory statements about the driving force of aromatic stabilization. Currently, these contradictions have not been resolved and have resulted in a confusing distinction between two different types of aromaticity: extrinsic and intrinsic aromaticity. By investigating different homodesmotic reactions we show that, in contrast to ASE itself, the individual contributions that enter the ASE can strongly depend on the type of reaction. Caution is therefore advised if conclusions or physical interpretations are derived from the individual components. The contradictions result from the fact that some reactions suffer from an imbalance in the number of interaction terms at the two sides of the reaction equation. The concept of isointeractional reactions is introduced and results in the elimination of the imbalance. For these reactions, the contradictions disappear and the distinction between intrinsic and extrinsic aromaticity becomes unnecessary. As far as the σ–π partitioning is concerned, several schemes proposed in the literature are compared. Contradictory results are obtained depending on the partitioning scheme and reaction used. In this context, it is demonstrated that for the partitioning of the electron–electron interaction, the scheme introduced by Jug and Köster is the one that is most theoretically grounded.
Zebrafish bashful/laminin‐α1 mutants exhibit multiple axon guidance defects
Authors: Paulus Jeremiah D. , Halloran Mary C. 
Published: October 2005

AbstractLaminin is known to provide a highly permissive substratum and in some cases directional information for axon outgrowth in vitro. However, there is still little known about laminin function in guiding axons in vivo. We investigated the axon guidance role of laminin‐α1 in the developing zebrafish nervous system. Analysis of zebrafish bashful (bal)/laminin‐a1 mutants revealed multiple functions for laminin‐α1 in the outgrowth and guidance of central nervous system (CNS) axons. Most CNS axon pathways are defective in bal embryos. Some axon types, including retinal ganglion cell axons, early forebrain axons, and hindbrain reticulospinal axons, make specific pathfinding errors, suggesting laminin‐α1 is required for directional decisions. Other axon tracts are defasciculated or not fully extended in bal embryos, suggesting a function for laminin‐α1 in regulating adhesion or providing a permissive substratum for growth. In addition, some neurons have excessively branched axons in bal, indicating a potential role for laminin‐α1 in branching. In contrast to CNS axons, most peripheral axons appear normal in bal mutants. Our results, thus, reveal important and diverse functions for laminin‐α1 in guiding developing axons in vivo. Developmental Dynamics 235:213–224, 2006. © 2005 Wiley‐Liss, Inc.
Sema3D, Sema3F, and Sema5A are expressed in overlapping and distinct patterns in chick embryonic heart
Authors: Jin Zhe , Chau Mary D. , Bao Zheng‐Zheng 
Published: October 2005

AbstractAn increasing number of axon guidance cues have been shown recently to play important roles in the development of non‐neural tissues. Semaphorins comprise one of the largest conserved families of axon guidance factors. We analyzed the expression patterns of Sema3D, Sema3F, and Sema5A genes in the chick embryonic heart by in situ hybridization. All three genes are expressed in the cardiac cushion regions, both in the mesenchymal cells, and epithelial cells in the endocardial layer, during the period of cardiac remodeling. In addition to the overlapping expression patterns in the cardiac cushion regions, these genes also exhibit distinct expression patterns in the developing heart: Sema3D is additionally expressed in the tips of the ventricular trabeculae; Sema3F is expressed in a subset of cells scattered throughout the ventricles; and Sema5A is expressed in the newly formed atrioventricular valves. The overlapping and distinct expression patterns of these genes suggest that they may play important roles in heart development. Developmental Dynamics 235:163–169, 2006. © 2005 Wiley‐Liss, Inc.
Hypoxia suppresses the production of matrix metalloproteinases and the migration of humanmonocyte‐derived dendritic cells
Authors: Zhao Wenli , Darmanin Stephanie , Fu Qiang , Chen Jian , Cui Hongyan , Wang Jingxin , Okada Futoshi , Hamada Jun‐ichi , Hattori Yuu‐ichi , Kondo Takeshi , Hamuro Junji , Asaka Masahiro , Kobayashi Masanobu 
Published: October 2005

AbstractAs most solid tumors are hypoxic, dendritic cells (DC) in solid tumors are also exposed to hypoxia. While many adaptation responses of tumor cells to hypoxia are known, it is yet to be determined how hypoxia affects the functions of DC. To explore the effects of hypoxia on the functions of DC, we compared the expression of surface markers, cytokines, chemokine receptors and matrix metalloproteinases (MMP) of human monocyte‐derived DC (hmDC) differentiated under hypoxia to those differentiated under normoxia. Both groups of hmDC expressed similar levels of surface markers and cytokines. However, expression of MMP‐9 and membrane type‐1‐MMP, as well as migrating activity, was significantly suppressed in hmDC differentiated under hypoxia compared with their normoxia counterparts. We also demonstrated that trichostatin A restored the production of MMP‐9 in hmDC, under hypoxia. Collectively, our findings show that a hypoxic microenvironment suppresses the production of MMP in hmDC, most probably through the deacetylation of promoter regions of MMP, thus suppressing the migrating activity of hmDC. Our results suggest that the hypoxic microenvironment in solid tumor tissues may suppress the function of DC.
The CD3 γϵ/δϵ signaling module provides normal T cell functions in the absence of the TCR ζ immunoreceptor tyrosine‐based activation motifs
Authors: Pitcher Lisa A. , Mathis Meredith A. , Young Jennifer A. , DeFord Laura M. , Purtic Bozidar , Wulfing Christoph , van Oers Nicolai S. C. 
Published: October 2005

AbstractT cell receptor (TCR) signal transduction is mediated by the immunoreceptor tyrosine‐based activation motifs (ITAM). The ten ITAM in the TCR complex are distributed in two distinct signaling modules termed TCR ζζ and CD3 γϵ/δϵ. To delineate the specific role of the ζ ITAM in T cell development and TCR signal transmission, we compared the properties of T cells from different TCR ζ‐transgenic lines wherein tyrosine‐to‐phenylalanine substitutions had been introduced in the ζ subunit. These lines lack selected phosphorylated forms of TCR ζ including just p23, both p21 and p23, or all phospho‐ζ derivatives. We report herein that the efficiency of positive selection in HY TCR‐transgenic female mice was directly related to the number of ζ ITAM in the TCR. In contrast, TCR‐mediated signal transmission and T cell proliferative responses following agonist peptide stimulation were similar and independent of the ζ ITAM. Only the duration of MAPK activation was affected by multiple ζ ITAM substitutions. These results strongly suggest that the ITAM in the CD3 γϵ/δϵ module can provide normal TCR signal transmission, with ζ ITAM providing a secondary function facilitating MAPK activation and positive selection.
ABCB1 transporter discriminates human resting naive B cells from cycling transitional and memory B cells
Authors: Wirths Stefan , Lanzavecchia Antonio 
Published: October 2005

AbstractThe exact identification of B cell subsets is instrumental to understand their dynamics under physiological and pathological conditions. Human memory B cells are currently identified according to the expression of CD27, which is absent on naive B cells. We report here that the ATP‐binding cassette (ABC)B1 transporter is exclusively present on mature CD27– naive B cells, while it is absent in CD27+ memory B cells and in a heterogeneous subset of CD27– cells that comprise both switch memory and transitional B cells. Thus, ABCB1 activity precisely discriminates naive from transitional and all memory B cells. Using this improved method to discriminate human B cell subsets, and Ki67 staining to identify recently divided cells, we show that in both cord blood and adult peripheral blood, mature naive B cells are quiescent while transitional B cells and memory B cells have a high in vivo turnover.