bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical study of spiramycin and its determination in pharmaceutical preparation
Authors: Youssef Rasha M. , Maher Hadir M. 
Published: May 2010

AbstractSpiramycin (SPY) is a medium‐spectrum antibiotic with high effectiveness against Gram‐positive bacteria. The voltammetric behaviour of spiramycin was studied using differential pulse polarography (DPP) and square wave polarography (SWP). The drug in Britton‐Robinson buffer (pH 11.5) is reduced at − 1.45 V, giving rise to a well‐defined cathodic peak using hanging mercury drop electrode (HMDE) versus Ag/AgCl electrode. This peak is attributed to the reduction of the aldehyde group. The results proved that the reduction of SPY is an irreversible diffusion‐controlled process. The diffusion current‐concentration relationship was shown to be rectilinear over the range of 20–80 and 0.8–80 µg ml−1 using DPP and SWP modes, respectively, with detection limit of 8.5 µg ml−1 (1.01 × 10−5 M) and 0.46 µg ml−1 (5.46 × 10−7 M) for DPP and SWP modes, respectively. A mechanism is postulated for the reduction of SPY. The proposed techniques were successfully applied to the determination of the studied compound either in pure form or in its formulation. Copyright © 2010 John Wiley & Sons, Ltd.
Coupled ecological–hydrological processes
Authors: Manfreda Salvatore , Smettem Keith , Iacobellis Vito , Montaldo Nicola , Sivapalan Murugesu 
Published: May 2010

AbstractThe papers in this issue represent a selection of the presentations made at the session entitled “Climate‐soil and vegetation interactions in ecological–hydrological processes” of the European Geophysical Union General Assembly. The special issue “Coupled Ecological–Hydrological Processes” focuses on different aspects of Ecohydrology that can be summarized in the following topics: soil moisture dynamics, soil–plant interactions, vegetation modelling and effects of climate change on natural ecosystems. Copyright © 2010 John Wiley & Sons, Ltd.
Syntheses, Structures and Magnetic Properties of Trinuclear CuIIMIICuII (M = Cu, Ni, Co and Fe) and Tetranuclear [2×1+1×2] CuIIMnII–2CuII Complexes Derived from a Compartmental Ligand: The Schiff Base 3‐Methoxysalicylaldehyde Diamine Can also Stabilize a Cocrystal
Authors: Biswas Arpita , Ghosh Meenakshi , Lemoine Pascale , Sarkar Sohini , Hazra Susanta , Mohanta Sasankasekhar 
Published: May 2010

AbstractThe present investigation describes syntheses, characterization and studies of the mononuclear compound [CuIIL⊂(H2O)] (1), the triangular, trinuclear monophenoxido‐bridged compounds [{CuIIL}2MII(H2O)2](ClO4)2·nH2O [2 (M = Cu, n = 0), 3 (M = Ni, n = 3), 4 (M = Co, n = 0), 5 (M = Fe, n = 0)] and the tetrametallic self‐assembled complex [{CuIILMnII(H2O)3}{CuIIL}2](ClO4)2·H2O (6) derived from compartmental Schiff base ligand, H2L, which is the [2+1] condensation product of 3‐methoxysalicylaldehyde and trans‐1,2‐diaminocyclohexane. Single‐crystal X‐ray structures of 2, 5 and 6 were determined. Two pairs of terminal···central metal ions in the trinuclear cores in 2 and 5 are monophenoxido‐bridged. Interestingly, the CuO6 and FeO6 environments have tetragonally compressed octahedral geometries. On the other hand, the structure of 6 reveals that it is a [2×1+1×2] cocrystal of one diphenoxido‐bridged dinuclear [CuIILMnII(H2O)3]2+ dication and two mononuclear [CuIIL] moieties. Cocrystallization in 6 takes place as a result of water encapsulation. The variable‐temperature (2–300 K) magnetic susceptibilities of compounds 2–6 have been measured. The exchange integrals obtained are: the CuII3 compound 2, J = –78.9 cm–1; the CuIINiIICuII compound 3, J = –22.8 cm–1; the CuIICoIICuII compound 4, J = –7.8 cm–1; the CuIIFeIICuII compound 5, J = –3.0 cm–1; the CuII3MnII compound 6, J = –15.1 cm–1. The monophenoxido‐bridging core in 3 and 4 has been proposed after comparison of the structures and magnetic properties of these two compounds with those of 2, 5 and related other compounds. This paper presents rare examples of monophenoxido‐bridged CuIIMIICuII (M = Cu, Ni, Co and Fe) compounds, provides an understanding of the structures from magnetic exchange integrals, and, most importantly, reports on the first example of a cocrystal derived from a 3‐methoxysalicylaldehyde diamine compartmental ligand.
Examination of Water Oxidation by Catalysts Containing Cofacial Metal Sites
Authors: Wasylenko Derek J. , Ganesamoorthy Chelladurai , Koivisto Bryan D. , Berlinguette Curtis P. 
Published: May 2010

AbstractA series of bimetallic complexes were developed to examine how the distance between two juxtaposed {Ru(tpy)(bpy)Cl}1+ (2; tpy = 2,2′;6′,2″‐terpyridine; bpy = 2,2′‐bipyridine) units affect catalytic behavior in the context of water oxidation. The directionality imposed by the organic backbone for each of these “Pacman” complexes elicits idealized M···M distances of ca. 5, 10, and 12 Å for 4–6, respectively. Cyclic voltammetry indicates that intramolecular electronic communication occurs between the metal sites of 4, while the metal fragments are essentially electrochemically isolated for 5 and 6. Despite the disparate distances between the metal sites, each of these complexes are shown to mediate the CeIV‐driven oxidation of water in acidic media. Dioxygen evolution was monitored with an optical probe in the headspace of the reaction vessel, and independently verified by the detection of appropriate ratios of 18O‐18O, 18O‐16O, and 16O‐16O in GC–MS experiments using 18O‐labeled water. A fitting of the dioxygen evolution data indicates catalytic behavior that is first‐order with respect to catalyst concentration in all cases. This finding rules out the possibility that dioxygen formation occurs independently at each metal site simultaneously, and leaves open the possibility that O–O bond formation occurs by either both metal sites acting cooperatively, or at one metal site independent of the other. Taking into account the significant electrostatic repulsion between the two metal fragments in higher oxidation levels, we contend that the latter mechanism is the more likely scenario. Notwithstanding, complex 4 generates the largest kobs values among the bimetallic series, which suggests that the close proximity of another metal may benefit catalysis. A comparison of kobs and catalytic turnover numbers (TONs) of the bimetallic systems to the mononuclear complex 2, however, does not indicate an improvement in catalytic behavior. This is an important observation in the collective pursuit of efficient water oxidation catalysts.
Solid‐State Structures and Properties of Europium and Samarium Hydrides
Authors: Kohlmann Holger 
Published: May 2010

AbstractThe structural chemistry of europium and samarium hydrides in the solid state is very rich, ranging from typical ionic hydrides following the hydride‐fluoride analogy to complex transition metal hydrides and interstitial hydrides. While crystal structure, electrical, and magnetic properties suggest that europium is divalent in all hydrides investigated so far, samarium is easily transformed to a trivalent oxidation state in its hydrides and shows similarities to other lanthanide(III) hydrides. The problem of neutron absorption of europium and samarium, hampering crystal structure solution and limiting the available structural information, is discussed in detail, and practical solutions for neutron diffraction experiments are given.
Trapped in a Complex: the 1,2,4,5‐Tetrakis(tetramethylguanidino)benzene Radical Cation (ttmgb+·) with a Bisallylic Structure
Authors: Trumm Christine , Hübner Olaf , Kaifer Elisabeth , Himmel Hans‐Jörg 
Published: May 2010

AbstractIn this work we follow the reaction of the strong electron donor 1,2,4,5‐tetrakis(tetramethylguanidino)benzene (ttmgb) with CuII nitrate. Three binuclear CuII complexes were isolated as products of this reaction. Depending on the reaction conditions, especially the molar ratio of the two reactants, the ttmgb ligand in these complexes is neutral, mono‐ or dicationic. All three complexes were structurally characterized. In addition to the experimental studies, quantum chemical calculations were carried out, which, in combination with experimental magnetic (SQUID) curves, especially shed light on the magnetic superexchange. The binuclear CuII complex of the ttmgb radical cation represents a three‐spin system. The SQUID magnetic data as well as the results of quantum chemical calculations indicate strong ferromagnetic copper‐ligand coupling.
Spectroscopy of High‐Energy States of Lanthanide Ions
Authors: Reid Michael F. , Hu Liusen , Frank Sebastian , Duan Chang‐Kui , Xia Shangda , Yin Min 
Published: May 2010

AbstractWe discuss recent progress and future prospects for the analysis of the 4fN–15d excited states of lanthanide ions in host materials. We demonstrate how ab initio calculations for Ce3+ in LiYF4 may be used to estimate crystal‐field and spin‐orbit parameters for the 4f1 and 5d1 configurations. We show how excited‐state absorption may be used to probe the electronic and geometric structure of the 4fN–15d excited states in more detail and we illustrate the possibilities with calculations for Yb2+ ions in SrCl2.
Addition of Azomethine Ylides to Aldehydes: Mechanistic Dichotomy of Differentially Substituted α‐Imino Esters
Authors: Seashore‐Ludlow Brinton , Torssell Staffan , Somfai Peter 
Published: May 2010

AbstractThe formal 1,3‐dipolar cycloaddition of azomethine ylides and aldehydes is explored, as hydrolysis of the resulting oxazolidine product gives facile access to valuable syn‐β‐aryl‐β‐hydroxy‐α‐amino esters. The use of using benzaldehyde‐derived imines as the ylide precursor results in 1,3‐dipolar cycloaddition with high conversions but low diastereoselectivity. In contrast, the employment of benzophenone‐derived imines as the ylide precursor results in an aldol reaction, which gives the intermediate oxazolidine in high diastereoselectivity and requires a weak acid catalyst to achieve higher conversions.
Synthetic Exploration of Oxacalix[2]arene[2]quinazolines
Authors: Van Rossom Wim , Kishore Lingam , Robeyns Koen , Van Meervelt Luc , Dehaen Wim , Maes Wouter 
Published: May 2010

AbstractOxacalix[2]arene[2]quinazoline macrocycles were prepared in good yields, as mixtures of syn and anti isomers, through nucleophilic aromatic substitution cyclocondensation reactions of 2,4‐dichloroquinazolines and m‐dihydroxybenzenes. The macrocyclization conditions were optimized and the isomeric ratio was investigated by means of one‐step and fragment‐coupling approaches. The oxacalixarene substitution pattern could easily be varied by altering the dichloroquinazolinyl biselectrophilic and dihydroxyaryl bisnucleophilic building blocks. The solid‐state (1,3‐alternate) conformational behavior and the oxacalix[4]arene cavity size were explored by X‐ray diffraction studies.
Acidity as a factor in leaching of copper, chromium and arsenic from CCA-treated dimension lumber
Authors: Warner John E. , Solomon Keith R. 
Published: May 2010

Abstract
Samples of new and weathered utility lumber pressure-treated with chromated copper arsenate (CCA) were tested for leaching of copper, chromium and arsenic by submersion in leaching baths of various pH levels. Accumulation of metals was monitored in leachate at pH 3.5, 4.5, 5.5, 7.0 and 8.5 over a period of 40 d by atomic absorption spectroscopy. Copper, chromium and arsenic were found in the leachate of both new and weathered wood with significantly higher levels of all metals occurring at acidic pH levels. Up to 100% of CCA treatment metals were found to have leached at pH 3.5, whereas a maximum of 9% of metals leached at pH 8.5. Metal leaching was found to be higher in citric acid than in dilute sulfuric acid solutions. Leaching of copper, chromium and arsenic was not proportional to the amount of metal present before leaching.
A bioaccumulation bioassay for freshwater sediments
Authors: Mac Michael J. , Noguchi George E. , Hesselberg Robert J. , Edsall Carol C. , Shoesmith John A. , Bowker James D. 
Published: May 2010

Abstract
A laboratory bioassay is described for determining the bioavailability of contaminants from freshwater sediments. The bioassay consists of 10-d exposures to whole sediments under flow-through conditions. After testing five species, the fathead minnow (Pimephales promelas) and the earthworm (Lumbricus terrestris) were recommended for use in the test. When the availability of polychlorinated biphenyls (PCBs), Hg and Zn from Great Lakes sediments was examined in laboratory exposures, only the PCBs were accumulated. A field validation study demonstrated that the magnitude of accumulation in laboratory exposures was similar to that in organisms caged in the field. A protocol is recommended for using the test as a standardized bioaccumulation bioassay.
Opportunistic multiuser scheduling with reduced feedback load
Authors: Al‐Harthi Yahya S. 
Published: May 2010

AbstractIn this paper, we propose a reduced feedback opportunistic scheduling (RFOS) algorithm that reduces the feedback load while preserving the performance of opportunistic scheduling (OS). The RFOS algorithm is a modified version of our previously proposed algorithm, the DSMUDiv algorithm. The main difference is that RFOS consists of a probing process (search process) and a requesting feedback process based on a threshold. The threshold value is variable, and it depends on the probing process. To reduce the feedback rate, a quantised value indicating the modulation level is fed back, instead of the full value of the signal‐to‐noise ratio (SNR), which we call quantised SNR. The paper includes the closed‐form expressions of the probing load, feedback load and spectral efficiency. In addition, we investigate the effect of the scheduling delay on the system throughput (STH). Under slow Rayleigh fading assumption, we compare RFOS algorithm with the DSMUDiv and optimal (full feedback load) selective diversity scheduling algorithms. Copyright © 2010 John Wiley & Sons, Ltd.
Semiparametric forecast intervals
Authors: Wu Jason J. 
Published: May 2010

ABSTRACTConsider forecasting the economic variable Yt+h with predictors Xt, where h is the forecast horizon. This paper introduces a semiparametric method that generates forecast intervals of Yt+h|Xt from point forecast models. First, the point forecast model is estimated, thereby taking advantage of its predictive power. Then, nonparametric estimation of the conditional distribution function (CDF) of the forecast error conditional on Xt builds the rest of the forecast distribution around the point forecast, from which symmetric and minimum‐length forecast intervals for Yt+h|Xt can be constructed. Under mild regularity conditions, asymptotic analysis shows that (1) regardless of the quality of the point forecast model (i.e., it may be misspecified), forecast quantiles are consistent and asymptotically normal; (2) minimum length forecast intervals are consistent. Proposals for bandwidth selection and dimension reduction are made. Three sets of simulations show that for reasonable point forecast models the method has significant advantages over two existing approaches to interval forecasting: one that requires the point forecast model to be correctly specified, and one that is based on fully nonparametric CDF estimate of Yt+h|Xt. An application to exchange rate forecasting is presented. Copyright © 2010 John Wiley & Sons, Ltd.
Pricing real options under the constant elasticity of variance diffusion
Authors: Carlos Dias José , Pedro Vidal Nunes João 
Published: May 2010

AbstractMuch of the work on real options assumes that the underlying state variable follows a geometric Brownian motion with constant volatility. This paper uses a more general assumption for the state variable process that better captures the empirical regularities found in commodity markets. We use the constant elasticity of variance diffusion, where volatility is a function of underlying asset prices, and we provide analytic solutions for perpetual American options. We show that a firm that uses the standard lognormal assumption is exposed to significant errors of analysis, which may lead to nonoptimal investment and disinvestment decisions. © 2010 Wiley Periodicals, Inc. Jrl Fut Mark 31:230–250, 2011
AP2 transcription factor induces apoptosis in retinoblastoma cells
Authors: Li Xiaodong , Glubrecht Darryl D. , Godbout Roseline 
Published: May 2010

AbstractThe underlying cause of human retinoblastoma is complete inactivation of both copies of the RB1 gene. Other chromosome abnormalities, with the most common being extra copies of chromosome arm 6p, are also observed in retinoblastoma. The RB protein has previously been shown to interact with TFAP2 transcription factors. Here, we show that TFAP2A and TFAP2B, which map to chromosome arm 6p, are expressed in the amacrine and horizontal cells of human retina. TFAP2A RNA can readily be detected in retinoblastoma cell lines and tumors; however, the great majority of retinoblastoma cell lines and tumors are completely devoid of TFAP2A protein and TFAP2B RNA/protein. Transfection of TFAP2A and TFAP2B expression constructs into retinoblastoma cells induces apoptosis and inhibits proliferation. Our results suggest that a consequence of loss of RB1 gene function in retinoblastoma cells is inactivation of TFAP2A and TFAP2B function. We propose that inability to differentiate along the amacrine/horizontal cell lineages may underlie retinoblastoma tumor formation. © 2010 Wiley‐Liss, Inc.
Mineralogy, geochemistry and geodynamic setting of the granitoids from NW Iran
Authors: Saki Adel 
Published: May 2010

AbstractThe Mahneshan granitoids intruded the Neoproterozoic‐Lower Cambrian regional metamorphic rocks in northwestern Iran. These granitoids consisting mainly of K‐feldspar, plagioclase, quartz, muscovite, garnet and biotite display a number of subtypes in terms of structure, texture and mineralogy. Geochemically, they are peraluminous and (or) slightly peraluminous with variable normative corundum contents (0.28–4.50%), and medium to high potassic with calc‐alkaline affinity. Chondrite‐normalized REE patterns indicate that these granitoids can be divided into three distinct groups, supported by petrographic data. The REE patterns of the first group are shallow‐sloping in LREE relative to HREE ([La/Yb]n = 1.37–2.48), exhibiting pronounced negative Eu (Eu/Eu* = 0.23–0.35). The second group granitoids are characterized by strong LREE‐enrichment relative to HREE ([La/Yb]n = 3–6.20), with positive Eu anomalies (Eu/Eu* = 1.15–1.47). The third group of granitoids is depleted in the middle REE relative to other LREE and HREE. These REE patterns suggest the role of plagioclase and hornblende in their source of granitoids for group 1 and groups 2 and 3, respectively. The trends of Eu/Eu* ratio versus silica contents suggest mixing of mafic material with components formed by crustal melting with a plagioclase‐rich residue. Furthermore, thermobarometric estimations indicate that these rocks may have been formed at depths of 15–18 km at relatively low temperatures. The Mahneshan granitoids are S‐type and may have been emplaced in a syn‐ to post‐collisional tectonic setting, consistent with an origin of water‐saturated magmas with heterogeneous composition derived from different crustal rocks. Copyright © 2010 John Wiley & Sons, Ltd.
Control of oligodendrocyte generation and proliferation by Shp2 protein tyrosine phosphatase
Authors: Zhu Ying , Park Jinsil , Hu Xuemei , Zheng Kang , Li Hong , Cao Qilin , Feng Gen‐Sheng , Qiu Mengsheng 
Published: May 2010

AbstractExtracellular signals play essential roles in controlling the proliferation and differentiation of oligodendrocyte progenitor cells in the developing central nervous system. However, the intracellular pathways that transduce these extrinsic signals remain to be elucidated. In this study, we showed that conditional ablation of the nonreceptor tyrosine phosphatase Shp2 in Olig1‐expressing oligodendrocyte lineage resulted in dramatic reduction in the generation and proliferation of oligodendrocyte progenitor cells in the spinal cord. Maturation and myelination of oligodendrocytes were also compromised in the Shp2 mutants. The deficits in oligodendrocyte development in Shp2 mutants nearly phenocopied those observed in PDGF‐A mutants, suggesting that Shp2 is a crucial component in transducing PDGF‐A signals in the control of oligodendrocyte proliferation and maturation. © 2010 Wiley‐Liss, Inc.
Secondary sensory area SII is crucially involved in the preparation of familiar movements compared to movements never made before
Authors: Beudel M. , Zijlstra S. , Mulder Th. , Zijdewind I. , de Jong B.M. 
Published: May 2010

AbstractSecondary sensorimotor regions are involved in sensorimotor integration and movement preparation. These regions take part in parietal‐premotor circuitry that is not only active during motor execution but also during movement observation and imagery. This activation particularly occurs when observed movements belong to one's own motor repertoire, consistent with the finding that motor imagery only improves performance when one can actually make such movement. We aimed to investigate whether imagery or observation of a movement that was never made before causes parietal‐premotor activation or that the ability to perform this movement is indeed a precondition. Nine subjects [group Already Knowing It (AKI)] could abduct their hallux (moving big toe outward). Seven subjects initially failed to make such movement (Absolute Zero A0 group). They had to imagine, observe, or execute this movement, whereas fMRI data were obtained both before and after training. Contrasting abduction observation between the AKI‐group and A0‐group showed increased left SII and supplementary motor area activation. Comparing the observation of hallux flexion with abduction showed increased bilateral SII activation in the A0 and not in the AKI group. Prolonged training resulted in equal performance and similar cerebral activation patterns in the two groups. Thereby, conjunction analysis of the correlations on subject's range of abduction during execution, imagery, and observation of hallux abduction showed exclusive bilateral SII activation. The reduced SII involvement in A0 may imply that effective interplay between sensory predictions and feedback does not take place without actual movement experience. However, this can be acquired by training. Hum Brain Mapp, 2011. © 2010 Wiley‐Liss, Inc.