bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Molecular Paddlewheel with a Sliding Organometallic Latch: Syntheses, X‐Ray Crystal Structures and Dynamic Behaviour of [Cr(CO)3{η6‐2‐(9‐triptycyl)indene}], and of [M(CO)3{η5‐2‐(9‐triptycyl)indenyl}] (M=Mn, Re)
Authors: Nikitin Kirill , Müller‐Bunz Helge , Ortin Yannick , McGlinchey Michael J. 
Published: January 2009

AbstractMetal clamping in operation! Deprotonation of [η6‐2‐(9‐triptycyl)indene]tricarbonylchromium induces a haptotropic shift of the organometallic fragment from the six‐membered to the five‐membered ring, as in a→b. In the anion, rotation of the molecular paddlewheel is blocked by the bulky tripod. X‐ray crystal structures provide pictures of the system in both its “ON” and “OFF” states.magnified imageIn [η6‐2‐(9‐triptycyl)‐indene]tricarbonylchromium (2 a), the indenyl–chromium moiety is linked directly to the axis of the three‐bladed triptycene paddlewheel. However, the molecular structure of 2 a reveals that there is no steric interaction between these components, and the paddlewheel is free to rotate. Accordingly, its NMR spectrum indicates the full equivalence of the blades of the triptycene. Deprotonation of the indene induces a haptotropic shift of the organometallic fragment from the six‐membered to the five‐membered ring of the indene and, in the sodium [η5‐2‐(9‐triptycyl)‐indenyl]tricarbonylchromium salt (3 a), so formed, rotation of the three‐bladed molecular paddlewheel is now blocked by the bulky tripod. NMR data for 3 a, and also for the isostructural η5‐Mn(CO)3 and η5‐Re(CO)3 complexes, 3 b and 3 c, respectively, reveal a 2:1 splitting of the blades of the triptycyl moiety, thus breaking its original threefold symmetry. The X‐ray crystal structures of the chromium complex, 2 a, and of the manganese and rhenium complexes, 3 b and 3 c, provide pictures of the system in both its “ON” and “OFF” states, whereby the M(CO)3 tripod has moved about 2 Å towards the triptycene, thus blocking its rotation. Comparison of the rotational barriers in 2‐(9‐triptycyl)indene (1) and its complexes 2 and 3, suggests that rotation of the paddlewheel can be slowed by a factor of approximately 108.
1,3‐Dioxolane‐Based Ligands as Rigid Analogues of Naftopidil: Structure–Affinity/Activity Relationships at α1and 5‐HT1AReceptors
Authors: Sorbi Claudia , Franchini Silvia , Tait Annalisa , Prandi Adolfo , Gallesi Rossella , Angeli Piero , Marucci Gabriella , Pirona Lorenza , Poggesi Elena , Brasili Livio 
Published: January 2009

AbstractConformational restrictionof naftopidil led to the discovery of a new class of ligands with a 1,3‐dioxolane (1,3‐oxathiolane, 1,3‐dithiolane) structure that bind to α1adrenoceptor subtypes and 5‐HT1Areceptors. Adequate structural modifications address the selectivity toward one or the other receptor system.magnified imageConformational restriction of naftopidil proved to be compatible with binding at α1adrenoceptor subtypes and 5‐HT receptor 1A (5‐HT1A), and led to the discovery of a new class of ligands with a 1,3‐dioxolane (1,3‐oxathiolane, 1,3‐dithiolane) structure. Compound7shows the highest affinity toward α1aand α1dadrenoceptor subtypes (pKi α1a=9.58, pKi α1d=9.09) and selectivity over 5‐HT1Areceptors (α1a/5‐HT1A=100, α1d/5‐HT1A=26). In functional experiments it behaves as a potent competitive α1aand α1dadrenoceptor antagonist (pKb α1A=8.24, pKb α1D=8.14), whereas at 5‐HT1Areceptors it is a potent partial agonist (pD2=8.30). Compounds8and10display high affinity (pKi=8.29 and 8.26, respectively) and selectivity for 5‐HT1A(5‐HT1A/α1=18 and 10). In functional experiments at the 5‐HT1Areceptor, compound8appears to be neutral antagonist (pKb=7.29), whereas compound10is a partial agonist (pD2=6.27). Therefore, 1,3‐dioxolane‐based ligands are a versatile class of compounds useful for the development of more selective ligands for one (α1) or the other (5‐HT1A) receptor system.
SHOP: A Method For Structure‐Based Fragment and Scaffold Hopping
Authors: Fontaine Fabien , Cross Simon , Plasencia Guillem , Pastor Manuel , Zamora Ismael 
Published: January 2009

AbstractWe present a method for fragment/scaffold substitution based on protein–ligand interactions. This concept goes beyond bioisosteric replacement, which only uses the structure of the fragment to replace as query. The methodology is validated with more than 10 biological targets relevant for drug discovery.magnified imageA new method for fragment and scaffold replacement is presented that generates new families of compounds with biological activity, using GRID molecular interaction fields (MIFs) and the crystal structure of the targets. In contrast to virtual screening strategies, this methodology aims only to replace a fragment of the original molecule, maintaining the other structural elements that are known or suspected to have a critical role in ligand binding. First, we report a validation of the method, recovering up to 95 % of the original fragments searched among the top‐five proposed solutions, using 164 fragment queries from 11 diverse targets. Second, six key customizable parameters are investigated, concluding that filtering the receptor MIF using the co‐crystallized ligand atom type has the greatest impact on the ranking of the proposed solutions. Finally, 11 examples using more realistic scenarios have been performed; diverse chemotypes are returned, including some that are similar to compounds that are known to bind to similar targets.
Ground plan of the insect mushroom body: Functional and evolutionary implications
Authors: Strausfeld Nicholas J. , Sinakevitch Irina , Brown Sheena M. , Farris Sarah M. 
Published: January 2009

AbstractIn most insects with olfactory glomeruli, each side of the brain possesses a mushroom body equipped with calyces supplied by olfactory projection neurons. Kenyon cells providing dendrites to the calyces supply a pedunculus and lobes divided into subdivisions supplying outputs to other brain areas. It is with reference to these components that most functional studies are interpreted. However, mushroom body structures are diverse, adapted to different ecologies, and likely to serve various functions. In insects whose derived life styles preclude the detection of airborne odorants, there is a loss of the antennal lobes and attenuation or loss of the calyces. Such taxa retain mushroom body lobes that are as elaborate as those of mushroom bodies equipped with calyces. Antennal lobe loss and calycal regression also typify taxa with short nonfeeding adults, in which olfaction is redundant. Examples are cicadas and mayflies, the latter representing the most basal lineage of winged insects. Mushroom bodies of another basal taxon, the Odonata, possess a remnant calyx that may reflect the visual ecology of this group. That mushroom bodies persist in brains of secondarily anosmic insects suggests that they play roles in higher functions other than olfaction. Mushroom bodies are not ubiquitous: the most basal living insects, the wingless Archaeognatha, possess glomerular antennal lobes but lack mushroom bodies, suggesting that the ability to process airborne odorants preceded the acquisition of mushroom bodies. Archaeognathan brains are like those of higher malacostracans, which lack mushroom bodies but have elaborate olfactory centers laterally in the brain. J. Comp. Neurol. 513:265–291, 2009. © 2009 Wiley‐Liss, Inc.
Transcriptional re‐programming of primary macrophages reveals distinct apoptotic and anti‐tumoral functions of IRF‐3 and IRF‐7
Authors: Goubau Delphine , Romieu‐Mourez Raphaëlle , Solis Mayra , Hernandez Eduardo , Mesplède Thibault , Lin Rongtuan , Leaman Douglas , Hiscott John 
Published: January 2009

AbstractThe immunoregulatory transcriptional modulators – IFN‐regulatory factor (IRF)‐3 and IRF‐7 – possess similar structural features but distinct gene‐regulatory potentials. For example, adenovirus‐mediated transduction of the constitutively active form of IRF‐3 triggered cell death in primary human MΦ, whereas expression of active IRF‐7 induced a strong anti‐tumoral activity in vitro. To further characterize target genes involved in these distinct cellular responses, transcriptional profiles of active IRF‐3‐ or IRF‐7‐transduced primary human MΦ were compared and used to direct further mechanistic studies. The pro‐apoptotic BH3‐only protein Noxa was identified as a primary IRF‐3 target gene and an essential regulator of IRF‐3, dsRNA and vesicular stomatitis virus‐induced cell death. The critical role of IRF‐7 and type I IFN production in increasing the immunostimulatory capacity of MΦ was also evaluated; IRF‐7 increased the expression of a broad range of IFN‐stimulated genes including immunomodulatory cytokines and genes involved in antigen processing and presentation. Furthermore, active IRF‐7 augmented the cross‐presentation capacity and tumoricidal activity of MΦ and led to an anti‐tumor response against the B16 melanoma model in vivo. Altogether, these data further highlight the respective functions of IRF‐3 and IRF‐7 to program apoptotic, immune and anti‐tumor responses.
Changes in triacylglycerol molecular species and thermal properties of blended and interesterified mixtures of coconut oil or palm oil with rice bran oil or sesame oil
Authors: Reena Malongil B. , Reddy Sunki R. Y. , Lokesh Belur R. 
Published: January 2009

AbstractBlended oils were prepared by mixing appropriate amounts of coconut oil (CNO) or palm oil (PO) with rice bran oil (RBO) or sesame oil (SESO) to get approximately equal proportions of saturated/monounsaturated/polyunsaturated fatty acids in the oil. These blended oils were subjected to interesterification reactions using lipase to randomize the fatty acid distribution on the glycerol molecule. The fatty acid compositions of the modified oils were evaluated by gas chromatography while changes in triacylglycerol molecular species were followed by HPLC. The triacylglycerol molecular species of the blended oils reflected those present in the parent oil. Interesterification of the blended oils resulted in the exchange of fatty acids within and between the triacylglycerol molecules, resulting in alterations in the existing triacylglycerol molecules. Emergence of new triacylglycerol molecular species following interesterification was also observed. The thermal profiles of the native, blended and interesterified oils were determined by differential scanning calorimetry. Thermal behaviour, melting and crystallization properties of the modified oils showed significant changes reflecting the changes in the triacylglycerol molecules present in the oil. Therefore, interesterification of oils introduces significant changes in the physical properties of oils, even though the overall fatty acid composition of blended and interesterified oils remains the same.
Cyclic 2:1 and 1:2 Aldehyde‐to‐Acetone Byproduct Adducts in Aldol Reactions Promoted by Supported Proline‐Incorporated Catalysts
Authors: Tuchman‐Shukron Lital , Kehat Tzofit , Portnoy Moshe 
Published: January 2009

AbstractSignificant amounts of cyclic byproducts of aldol addition with stoichiometry deviating from a regular 1:1 addition pattern were formed when the reaction of acetone with aromatic aldehydes was promoted by polymer‐supported proline‐incorporated catalysts. These adducts, unprecedented in the context of the aldol reaction, are most probably formed via a multistep domino mechanism.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Genosensor for SARS Virus Detection Based on Gold Nanostructured Screen‐Printed Carbon Electrodes
Authors: Martínez‐Paredes Graciela , González‐García María Begoña , Costa‐García Agustín 
Published: January 2009

AbstractA hybridization‐based genosensor is designed on a disposable gold nanostructured screen‐printed carbon electrode. Gold nanoparticles which are formed in situ by applying a constant current intensity during a fixed time, acts as an immobilization and transduction surface. The parameters affecting the methodology are studied, with special attention being placed on sensibility. Immobilization takes place through thiol‐gold interaction in a relatively fast way, and the genosensor response is found to be linearly to the biotinylated target concentration between 2.5 and 50 pmol/L; a detection limit of 2.5 pmol/L is calculated, and a sensitivity of 1.76 μA/pmol L−1 is achieved. These results improve significantly those described in literature, thus demonstrating the advantages offered by the use of gold‐nanostructured surfaces.
Cathodic Electrochemical Determination of Herbicides in Acid Media Using a Bismuth Film Electrode
Authors: Moreno Mónica , Bermejo Esperanza , Chicharro Manuel , Zapardiel Antonio , Arribas Alberto Sánchez 
Published: January 2009

AbstractA revised procedure for the preparation of bismuth film electrodes (BiFEs), adapted to improve its performance in acid media, is presented and applied for the analysis of herbicides under these conditions. Common carbon‐based substrates have been studied for the preparation of ex situ BiFE as well as the influence of relevant parameters upon the bismuth film formation (plating solution, deposition potential and deposition time). A plating solution consisting of 0.60 mM Bi(NO3)3 in 0.10 M H2SO4 and a careful selection of the plating potential (equal to the cathodic peak potential in this solution) applied during 360 s yields to a suitable BiFE in terms of stability and electroanalytical performance. The applicability of the BiFE was investigated for the analysis of the herbicides metamitron, metribuzin, maleic hydrazide and atrazine in nondeaerated solutions by square‐wave voltammetry (SWV). In all cases the enhanced electrochemical performance of the BiFE over bare glassy carbon electrode (GCE) is evident. Herbicides signals at BiFE have improved sensitivity and a positive potential shift is observed when compared to bare GCE. The herbicide metribuzin (4‐amino‐6‐tert‐4,5‐dihydro‐3‐methyl‐thio‐1,2,4‐triazin‐5‐one) was determinated in nondeaerated solutions by square‐wave voltammetry (SWV) using BiFE. Under optimal conditions, the dynamic linear range of concentrations is comprised between 10 and 200 μM and the detection limit is 6 μM.
Current‐Free Deposition of Prussian Blue with Organic Polymers: Towards Improved Stability and Mass Production of the Advanced Hydrogen Peroxide Transducer
Authors: Borisova Anastasiya V. , Karyakina Elena E. , Cosnier Serge , Karyakin Arkady A. 
Published: January 2009

AbstractWe report on a novel approach for open‐circuit (current‐free) deposition of Prussian blue. Synthesis of Prussian blue is carried out by reduction of ferric ferricyanide with organic molecules, which are known to form polymers upon oxidation. The proposed interfacial deposition is a result of the synthesis in the presence of electrode support due to preconcentration of precursors at the interface. The resulting modified electrodes displayed the dramatically improved operational stability in hydrogen peroxide continuous monitoring with no loss of either electrochemical or analytical performance characteristics compared to electrodes with electrochemically deposited Prussian blue. The shown possibility to deposit stable films with regular structure in the absence of any external voltage could open new horizons for sensor science.
Resolution of Heavy Metal Mixtures from Highly Overlapped ASV Voltammograms Employing a Wavelet Neural Network
Authors: Gutiérrez Juan Manuel , Moreno‐Barón Laura , Céspedes Francisco , Muñoz Roberto , del Valle Manuel 
Published: January 2009

AbstractThis work describes the chemometric assisted ASV determination of three heavy metals in water (lead, copper and cadmium) in presence of thallium and indium as interfering species. Stripping was carried out in open atmosphere, employing a graphite‐epoxy transducer as working electrode, without any surface regeneration after each analysis. The concentration range studied was from 0.4 to 20 ppm for both analytes and interferents. Due to the overlapping nature of the signals, a wavelet neural network (WNN) was used for deconvolution of the voltammogram. In order to validate the resolution capability, a k‐fold cross validation procedure was performed. Mixtures of metals could be resolved with good prediction of their concentrations; obtained vs. expected comparison graphs exhibited, for a set of samples not employed for training, correlation values of 0.996 for lead, 0.989 for cadmium and 0.995 for copper.
System of Modular Design for Electroanalysis Extended to Thermoelectrochemical Studies
Authors: Gründler Peter 
Published: January 2009

AbstractAn instrument for electroanalysis extended to thermoelectrochemical studies is presented here consisting of easily available components. An analog potentiostat is combined with a microcontroller. The latter is controlled by an Excel sheet extended by macros written in VBA (visual basic for applications). The worksheet acts as a virtual instrument with front panel and command buttons. Thus, specialized, expansive measuring software packages are unnecessary. The design of new techniques is facilitated by a of graphical representation of pulse sequences or the exciting waveforms. The instrument has proved to be useful for design and performance of non conventional electrochemical techniques working with additional parameters like irradiation or heat. Examples are given for thermoelectrochemical measuring sequences like TPV (temperature pulse voltammetry).
Multivariate Analysis for the Electrochemical Discrimination and Quantitation of Nitroaromatic Explosives
Authors: Polsky Ronen , Stork Christopher L. , Wheeler David R. , Steen William A. , Harper Jason C. , Washburn Cody M. , Brozik Susan M. 
Published: January 2009

AbstractA chemometric approach for the discrimination and quantification of nitroaromatic explosives is presented. The multivariate analysis of the square‐wave voltammetric data of trinitrotoluene, 2,6‐dinitrotoluene, 2,4‐dinitrotoluene, and 2‐nitrotoluene reduction was employed to extract subtle differences in the electrochemical response across multiple potentials on a bare glassy carbon, aminophenyl‐modified glassy carbon, and carboxylphenyl‐modified glassy carbon electrode surfaces allowing the electrochemical discrimination of the four different nitroaromatic analytes. A multivariate regression model was developed to differentiate and predict the concentrations of the structural isomers 2,6‐dinitrotoluene, and 2,4‐dinitrotoluene in mixture solutions.
Planform dynamics of braided streams
Authors: Bertoldi Walter , Zanoni Luca , Tubino Marco 
Published: January 2009

AbstractThe high dynamism and complexity of braided networks poses a series of open questions, significant for river restoration and management. The present work is aimed at the characterization of the morphology of braided streams, in order to assess whether the system reaches a steady state under constant flow conditions and, in that case, to determine how it can be described and on which parameters it depends. A series of 14 experimental runs were performed in a laboratory physical model with uniform sand, varying the discharge and the longitudinal slope. Planimetric and altimetric configurations were monitored in order to assess the occurrence of a steady state. A set of parameters was considered, such as the braid‐plain width and the number and typology of branches and nodes. Results point out that a relationship exists between braiding morphology and two dimensionless parameters, related to total water discharge and stream power. We found that network complexity increases at higher values of water discharge and a larger portion of branches exhibits morphological activity. Results are then compared to the outputs of a simple one‐dimensional model, that allows to easily predict the average network complexity, once the bed topography is known. Model computations permit also the investigation of the effect of water discharge variations and to compare different width definitions. The at‐a‐station variability of planimetric parameters shows a peculiar behaviour, both regarding number of branches and wetted width. In particular, the analysis of the relationship between width and discharge highlighted relevant differences in comparison to single thread channel. Copyright © 2009 John Wiley & Sons, Ltd.
Multi‐process Late Quaternary landscape evolution modelling reveals lags in climate response over small spatial scales
Authors: Temme A. J. A. M. , Veldkamp A. 
Published: January 2009

AbstractLandscapes evolve in complex, non‐linear ways over Quaternary timespans. Integrated geomorphological field studies usually yield plausible hypotheses about timing and impact of process activity. Landscape Evolution Models (LEMs) have the potential to test and falsify these landscape evolution hypotheses. Despite this potential, LEMs have mainly been used with hypothetical data and rarely to simulate the evolution of an actual landscape.In this paper, we use a LEM (LAPSUS: LandscApe ProcesS modelling at mUlti dimensions and scaleS) to explore if it is possible to test and falsify conclusions of an earlier field study on 50 ka landscape evolution in Okhombe Valley, KwaZulu Natal, South Africa. In this LEM, five landscape processes interact without supervision: water driven erosion and deposition, creep, solifluction, biological weathering and frost weathering. Calibration matched model results to three types of qualitative fieldwork observations: individual process activity over time, relative process activity over time and net landscape changes over time. Results demonstrate that landscape evolution of the Okhombe valley can be plausibly simulated.A particularly interesting and persistent feature of model results are erosional and depositional phases that lag climatic drivers both by decades, and by several ka within a few hundred meters. The longer lag has not been reported for this spatial scale before and may be an effect of slow landscape‐soil‐vegetation feedbacks. The combined modelling and fieldwork results allow a more complete understanding of these responses to climate change and can fill in hiatuses in the stratigraphical record. Suggestions are made for methodological adaptations for future LEM studies. Copyright © 2009 John Wiley & Sons, Ltd.
Reduced‐complexity flow routing models for sinuous single‐thread channels: intercomparison with a physically‐based shallow‐water equation model
Authors: Nicholas A. P. 
Published: January 2009

AbstractReduced‐complexity models of fluvial processes use simple rules that neglect much of the underlying governing physics. This approach is justified by the potential to use these models to investigate long‐term and/or fundamental river behaviour. However, little attention has been given to the validity or realism of reduced‐complexity process parameterizations, despite the fact that the assumptions inherent in these approaches may limit the potential for elucidating the behaviour of natural rivers. This study presents two new reduced‐complexity flow routing schemes developed specifically for application in single‐thread rivers. Output from both schemes is compared with that from a more sophisticated model that solves the depth‐averaged shallow water equations. This comparison provides the first demonstration of the potential for deriving realistic predictions of in‐channel flow depth, unit discharge, energy slope and unit stream power using simple flow routing schemes. It also highlights the inadequacy of modelling unit stream power, shear stress or sediment transport capacity as a function of local bed slope, as has been common practice in a number of previous reduced‐complexity models. Copyright © 2009 John Wiley & Sons, Ltd.