bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anion Template Effect and the Polymerization Degree – Diversity through Flexibility
Authors: Nättinen Kalle I. , de Bairos Paulo E. N. , Seppälä Petri J. , Rissanen Kari T. 
Published: June 2005

AbstractTwo 2D (M1 and M2) and one 1D (M3) metal‐organic frameworks (MOFs) have been prepared from pyridine functionalized tetradentate ligand tetrakis(nicotinoxymethyl)methane TNM with silver tetrafluoroborate, nickel chloride, and copper hexafluorophosphate. M1 manifests a previously unpresented mode of 4,4 threefold parallel interpenetration for 2D MOFs. Large channels (vdW diameter 9.4 Å) through eclipsed 2D layers of M2 were observed. While the open space percentage in the noninterpenetrated M2 was 38.0 %, the triple interpenetration of the sheets of M1 reduced the void to 10.8 %. With the same ligand and a similar, weakly coordinating anion as that in M1, the structure M3 was rendered one‐dimensional. The result is explained partly by the flexibility of the TNM ligand and partly by the lack of a suitable bridging solvent. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Reactions of Zirconocene Bis(trimethylsilyl)acetylene Complexes with Fluorinated Pyridines: C–H vs. C–F Bond Activation
Authors: Jäger‐Fiedler Ulrike , Arndt Perdita , Baumann Wolfgang , Spannenberg Anke , Burlakov Vladimir V. , Rosenthal Uwe 
Published: June 2005

AbstractThe zirconocene complexes Cp2Zr(L)(η2‐Me3SiC2SiMe3) (1a: L = THF; 1b: L = pyridine) and the ethylene bis(tetrahydroindenyl) complex rac‐(ebthi)Zr(η2‐Me3SiC2SiMe3) (2) react with 2,3,5,6‐tetrafluoropyridine with C–H bond activation to produce the 4‐substituted pyridyl complexes with agostic alkenyl groups Cp'2Zr(4‐C5NF4)[–C(SiMe3)=CH(SiMe3)] (Cp'2 = Cp2) (3) and (Cp'2 = ebthi) (4). With 2,3,4,6‐tetrafluoropyridine, after C–H bond activation, complex 2 yields two isomers of the 5‐substituted pyridyl complex rac‐(ebthi)Zr(3‐C5NF4)[–C(SiMe3)=CH(SiMe3)] with agostic alkenyl groups, 5a and 5b. With pentafluoropyridine complex 1b gives, after dissociation of the bis(trimethylsilyl)acetylene (btmsa), C–F bond activation at the 4‐position and formation of Cp2Zr(4‐C5NF4)F (6). Complex 1b reacts with 3‐chloro‐2,4,5,6‐tetrafluoropyridine by means of a preferred C–Cl activation to give Cp2Zr(3‐C5NF4)Cl (7). These results are in contrast to the reactions of the titanium complex Cp2Ti(η2‐Me3SiC2SiMe3) which, with 2,3,5,6‐tetrafluoropyridine, gaveC–F activation in preference to C–H activation. With pentafluoropyridine, C–F bond activation at the 2‐position was found rather than at the 4‐position. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
One‐Step Synthesis of Symmetrically Substituted 2,6‐Bis(pyrazol‐1‐yl)pyridine Systems
Authors: Zoppellaro Giorgio , Baumgarten Martin 
Published: June 2005

AbstractA one‐pot synthetic route that allows functionalization of the 2,6‐bis(pyrazol‐1‐yl)pyridine backbone in the 4‐ and 4″‐pyrazole positions by direct H(4)‐pyrazole halogen exchange is described. The diiodo derivative in particular provides easy access to additional functionalities through both Sonogashira and Grignard exchange reactions. These synthons represent optimal building blocks for the extension of the chelating core and for the assembly of rigid organic and metalloorganic nanostructures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Structures, Spectral and Electrochemical Properties ofN‐(Naphth‐2‐ylmethyl)‐Appended Porphyrinogens
Authors: Hill Jonathan P. , Schmitt Wolfgang , McCarty Amy Lea , Ariga Katsuhiko , D’Souza Francis 
Published: June 2005

AbstractAlkylation of 5,10,15,20‐tetrakis(3,5‐di‐tert‐butyl‐4‐oxo‐2,5‐cyclohexadienylidene)porphyrinogen at its macrocyclic nitrogen atoms results in four multiplyN‐substituted products, which were isolated and characterized. The electrochemical and spectroelectrochemical properties of these compounds were determined. Molecular structures of theN‐alkylated compounds are influenced strongly by intermolecular π‐π stacking interaction between naphthyl groups leading to formation of dimers or stacked arrays of the macrocycle depending on multiplicity of substituents. The redox and spectral properties of the compounds are related to the increasing multiplicity ofN‐substitution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Electrochemical, Chemical and Enzymatic Oxidations of Phenothiazines
Authors: Blankert B. , Hayen H. , van Leeuwen S. M. , Karst U. , Bodoki E. , Lotrean S. , Sandulescu R. , Diez N. Mora , Dominguez O. , Arcos J. , Kauffmann J.‐M. 
Published: June 2005

AbstractThe oxidation of several phenothiazine drugs (phenothiazine, promethazine hydrochloride, promazine hydrochloride, trimeprazine hydrochloride and ethopropazine hydrochloride) has been carried out in aqueous acidic media by electrochemical, chemical and enzymatic methods. The chemical oxidation was performed in acetic acid with hydrogen peroxide or in formate buffers using persulfate. The enzymatic oxidation was performed in acetate or ammonium formate buffer by the enzyme horseradish peroxidase in the presence of H2O2. Molecules with, in the lateral chain, two carbon atoms (2C) separating the ring nitrogen and the terminal nitrogen, showed two parallel oxidation pathways, that is (i) formation of the corresponding sulfoxide and (ii) cleavage of the lateral chain with liberation of phenothiazine (PHZ) oxidized products (PHZ sulfoxide and PHZ quinone imine). Molecules with three carbon atoms (3C) separating the two nitrogens were oxidized to the corresponding sulfoxide. The chemical oxidation of all the studied molecules by hydrogen peroxide resulted in the corresponding sulfoxide with no break of the lateral chain. Oxidation by persulfate yielded, for the 3C derivatives, only the corresponding sulfoxide, but it produced cleavage of the lateral chain for the 2C derivatives. The origin of the distinct oxidation pattern between 2C and 3C molecules might be related to steric effects due to the lateral chain. The data are of interest in drug metabolism studies, especially for the early search. In the case of 2C phenothiazines, the results predict the possibility of an in vivo cleavage of the lateral chain with liberation of phenothiazine oxidized products which are known to produce several adverse side effects.
Enzymatic Biosensor Based on Carbon Paste Electrodes Modified with Gold Nanoparticles and Polyphenol Oxidase
Authors: Miscoria Silvia A. , Barrera Gustavo D. , Rivas Gustavo A. 
Published: June 2005

AbstractThe results presented here demonstrate the important catalytic effect of a carbon paste electrode modified by dispersion of gold nanoparticles towards different electroactive compounds. The oxidation of hydrogen peroxide starts at potentials 400 mV less positive than at bare carbon paste, while the reduction, almost negligible at bare carbon paste, starts at 0.100 V. The influence of the size and amount of gold nanoparticles in the composite matrix on the response of the electrode is discussed. The incorporation of albumin within the carbon paste facilitates the dispersion of gold nanoparticles, improving substantially the catalytic effects. At carbon paste modified with gold nanoparticles and albumin, the peak potential separation for hydroquinone decreases from 0.385 V to 0.209 V while the reduction current increases from 16.6 to 75.2 μA. The immobilization of polyphenol oxidase within the carbon paste electrode modified with nanoparticles has allowed us to obtain a very sensitive biosensor for dopamine even in the presence of large excess of ascorbic acid.
Is Voltammetric Current Proportional to the Number of Transferred Electrons for Multi‐Charged Ions or to 3/2 Power of the Number?
Authors: Aoki Koichi 
Published: June 2005

AbstractParticles with a large number of electrons to transfer, such as nanoparticles and colloidal redox particles, give voltammetrric currents that were demonstrated theoretically to be proportional directly to the number of the electrons, n, rather than to n3/2. The latter quantity is included in the conventional expression for voltammetric peak currents of multi‐charge transfer processes. This apparent contradiction appears depending on whether the charge transfer occurs concurrently (n3/2) or consecutively (n). The expression for the linear sweep voltammetric current was derived from a combination of the diffusion equation for large particles with n electrons and the Nernst equation for the n‐time consecutive one‐electron reactions at the electrode. The power in n for the peak currents, in several voltammetric techniques, was demonstrated to be ascribed to the convolution of the Nernst equation and the diffusion equation.
EQCM Study of Iridium Anodic Oxidation in H2SO4 and KOH Solutions
Authors: Juodkazytė J. , Šebeka B. , Stalnionis G. , Juodkazis K. 
Published: June 2005

AbstractIn the present study anodic oxidation of iridium layer formed thermally on a gold‐sputtered quartz crystal electrode has been investigated by electrochemical quartz crystal microgravimetry (EQCM) in the solutions of 0.5 M H2SO4 and 0.1 M KOH. The emphasis here has been put on the microgravimetric behavior of iridium as a metal, because a few previous EQCM studies reported in literature have been devoted to iridium oxide films (IROFs). The objective pursued here has been to elucidate the nature of the main voltammetric peaks, which occur at different ranges of potential in the solutions investigated. It has been found that anodic oxidation of iridium electrode in 0.5 M H2SO4 and 0.1 M KOH solutions is accompanied by irregular fluctuations of the electrode mass at 0.4 V<E<0.8 V followed by regular increase in mass at 0.8 V<E<1.2 V. The cathodic process initially, at 1.2 V>E>0.9 V, proceeds without any or with slight increase in electrode mass, whereas at E<0.8 V a regular decrease in mass is observed. It has been found that mass to charge ratio characterizing the processes of interest is 2 to 3 g F−1in acidic medium, whereas in the case of alkaline one it is 4 to 6 g F−1. The main pair of peaks seen in the voltammograms of Ir electrode in alkaline medium at E<0.8 V is attributable to redox transition Ir(0)→Ir(III), whereas those observed in the case of acidic medium at E>0.8 V should be related to the redox process Ir(0)→Ir(IV) going via intermediate stage of Ir(III) formation. As a consequence of these redox transitions, the gel‐like surface layer consisting of Ir(III) or Ir(IV) hydrous oxides forms on the electrode surface.
Effect of Albumin on Underpotential Lead Deposition and Stripping on Ag‐RDE
Authors: Hepel Maria 
Published: June 2005

AbstractThe effects of adsorption of bovine serum albumin (BSA) on the electrodeposition and stripping of Pb‐adatoms at a Ag‐RDE in acetate buffer solutions have been studied. The adsorbed BSA molecules have been found to inhibit the lead adsorption process. A decrease in the apparent charge transfer coefficient α for Pb‐adatom desorption from 0.39 to 0.34 in the presence of adsorbed BSA molecules has been attributed to the electric field screening by multiply charged BSA in the adsorption film, since no major lateral interactions between Pb and BSA have been observed. The kinetics of BSA adsorption on a Ag‐RDE was followed by Pb‐adatom probe technique in the range of low BSA coverage, 0<θBSA<0.4. The adsorption (k1) and desorption (k−1) rate constants were determined as follows: k1=2.42×10−4 cm/s, k−1=1.12×10−14 mol cm−2 s−1. The equilibrium constant for BSA adsorption on Ag electrode from 3×10−8 M BSA solution, also determined from the Pb‐adatom probe method, was: Kads=2.17×107 L/mol and the corresponding Gibbs free energy of adsorption: ΔG°ads=−9.99 kcal/mol (−41.85 kJ/mol). The formation of BSA films on Ag electrodes has been confirmed by EQCN mass transients and AFM imaging. It follows from these experiments that BSA molecules adsorb in horizontal orientation and form a film on Ag with 4 nm thickness.
Analysis of Simulated Martian Regolith Using an Array of Ion Selective Electrodes
Authors: Lukow Stefan R. , Kounaves Samuel P. 
Published: June 2005

AbstractA prototype miniature array of polymer membrane and solid state ion selective electrodes was developed for the purpose of performing an in‐situ analysis of the soluble ionic species in Martian regolith (soil). The array contains a total of 27 electrodes for K+, Na+, Ca2+, Mg2+, NH$\rm{ {_{4}^{+}}}$, Ba2+, NO$\rm{ {_{3}^{-}}}$, Cl−, and Li+, each in triplicate. Barium electrodes were used to indirectly monitor sulfate through precipitation by the addition of barium chloride while the lithium electrodes served as a reference for the array by having a constant lithium concentration as a background for all solutions. The array was tested with several types of simulants, soils, and sawdust from a Mars meteorite, all with varying salt content, meant to approximate the various hypotheses regarding the ionic composition of the Martian soil. The activities of anions and cations determined with the array were compared to ion chromatography data.
Dose–time–response modeling of longitudinal measurements for neurotoxicity risk assessment
Authors: Zhu Yiliang 
Published: June 2005

AbstractNeurotoxic effects are an important non‐cancer endpoint in health risk assessment and environmental regulation. Neurotoxicity tests such as neurobehavioral screenings using a functional observational battery generate longitudinal dose–response data to profile neurological effects over time. Analyses of longitudinal neurotoxicological data have mostly relied on analysis of variance; explicit dose–time–response modeling has not been reported in the literature. As dose–response modeling has become an increasingly indispensible component in risk assessment as required by the use of benchmark doses, there are strong interests in and needs for appropriate dose–response models, effective model‐fitting techniques, and computation methods for benchmark dose estimation. In this article we propose a family of dose–time–response models, illustrate statistical inference of these models in conjunction with random‐effects to quantify inter‐subject variation, and describe a procedure to profile benchmark dose across time. We illustrate the methods through a dataset from a US/EPA experiment involving the FOB tests on rats administered to a single dose of triethyl tin (TET). The results indicate that the existing functional observational battery data can be utilized for dose–response and benchmark dose analyses and the methods can be applied in general settings of neurotoxicity risk assessment. Copyright © 2005 John Wiley & Sons, Ltd.
Monte Carlo integration strategies for design‐based regression estimators of the spatial mean
Authors: Barabesi L. , Marcheselli M. 
Published: June 2005

AbstractWhen a continuous population is sampled, the spatial mean is often the target parameter if the design‐based approach is assumed. In this case, auxiliary information may be suitably used to increase the accuracy of the spatial mean estimators. To this end, regression models are usually considered at the estimation stage in order to implement regression estimators. Since the spatial mean may be obviously represented as a bivariate integral, the strategies for placing the sampling locations are actually Monte Carlo integration methods. Hence, the regression‐based estimation is equivalent to the control‐variate integration method. In this setting, we suggest more refined Monte Carlo integration strategies which may drastically increase the regression estimator accuracy. Copyright © 2005 John Wiley & Sons, Ltd.
Evaluation of optimized variable area transect sampling using totally enumerated field data sets
Authors: Engeman Richard M. , Nielson Ryan M. , Sugihara Robert T. 
Published: June 2005

AbstractPlotless density estimators (PDEs) can be efficient alternatives to quadrat sampling for estimating the density of stationary objects. Variable area transect (VAT) sampling had been identified, and optimized relative to effort, in previous Monte Carlo simulated population studies as a low‐labor field method that demonstrated superior estimation properties among many PDEs considered. However, natural populations tend to be much more complex and less predictable in spatial distribution than computer generated populations. Therefore, we carried out a Monte Carlo simulation study that used 17 fully enumerated field populations rather than simulated populations. These natural populations represented a variety of population densities and spatial patterns. We focused on assessing the effect of the number of population members searched for along each transect (r), sample size, and transect width on estimation quality. Using relative root mean‐squared error and relative bias as criteria, the optimal range for r was 5 to 7 population members encountered from each start point. Sample size was best if n > 20, but returns in estimation quality diminished by n = 40. Transect width was previously uninvestigated and found to be the most important design factor affecting estimation quality. Field studies should strive for transects as wide as logistically reasonable. Published in 2005 John Wiley & Sons, Ltd.
Testing for separability of space–time covariances
Authors: Mitchell Matthew W. , Genton Marc G. , Gumpertz Marcia L. 
Published: June 2005

AbstractSeparable space–time covariance models are often used for modeling in environmental sciences because of their computational benefits. Unfortunately, there are few formal statistical tests for separability. We adapt a likelihood ratio test based on multivariate repeated measures to the spatio–temporal context. We apply this test to an environmental monitoring data set. Copyright © 2005 John Wiley & Sons, Ltd.
Information content of the fed funds rates
Authors: Sultan Jahangir 
Published: June 2005

AbstractThis study shows that the Fed Funds spot rate mostly affects the level of key interest rates while the Fed Funds futures rate tends to affect both the level and the volatility. Such effects are more concentrated on the shorter segment of the yield curve. In addition, only an unexpected change in the target rate affects both the level and the volatility of interest rates. Finally, the FOMC's increased disclosure of its policy stance has a calming effect on the volatility of key interest rates. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:753–774, 2005
Risk selection in the German public health insurance system
Authors: Nuscheler Robert , Knaus Thomas 
Published: June 2005

AbstractThe German statutory health insurance market was exposed to competition in 1996. To limit direct risk selection the regulator required open enrollment. As the risk compensation scheme, introduced in 1994, is highly incomplete, substantial incentives for risk selection exist. Due to their low premiums, company‐based sickness funds have been able to attract a lot of new members. We analyze, using data from the German Socio‐Economic Panel, the determinants of switching behavior from 1995 to 2000. There is no evidence for selection by funds. The success of the company‐based sickness funds originates in incomplete risk adjustment together with the negative correlation between health status and switching costs. Copyright © 2005 John Wiley & Sons, Ltd.
Pharmaceutical promotion and GP prescription behaviour
Authors: Windmeijer Frank , de Laat Eric , Douven Rudy , Mot Esther 
Published: June 2005

AbstractThe aim of this paper is to empirically analyse the responses by general practitioners to promotional activities for ethical drugs by pharmaceutical companies. Promotion can be beneficial as a means of providing information, but it can also be harmful in the sense that it lowers price sensitivity of doctors and it merely is a means of maintaining market share, even when cheaper, therapeutically equivalent drugs are available. A model is estimated that includes interactions of promotion expenditures and prices and that explicitly exploits the panel structure of the data, allowing for drug specific effects and dynamic adjustments, or habit persistence. The data used are aggregate monthly GP prescriptions per drug together with monthly outlays on drug promotion for the period 1994–1999 for 11 therapeutic markets, covering more than half of the total prescription drug market in the Netherlands. Identification of price effects is aided by the introduction of the Pharmaceutical Prices Act, which established that Dutch drugs prices became a weighted average of the prices in surrounding countries after June 1996. We conclude that GP drug price sensitivity is small, but adversely affected by promotion. Copyright © 2005 John Wiley & Sons, Ltd.
Economic development and the return to human capital: a smooth coefficient semiparametric approach
Authors: Mamuneas Theofanis P. , Savvides Andreas , Stengos Thanasis 
Published: June 2005

AbstractThis paper investigates the impact of human capital on the process of economic growth by allowing the contribution of traditional inputs (capital and labour) as well as that of human capital to vary both across countries and time. The former is accomplished by constructing an index of TFP growth for traditional inputs, while the latter through semiparametric methods. We derive estimates of the output elasticity and social return to human capital for 51 countries at various stages of economic development. Copyright © 2005 John Wiley & Sons, Ltd.
Lymphocytes and the foreign body response: Lymphocyte enhancement of macrophage adhesion and fusion
Authors: Brodbeck William G. , MacEwan Matthew , Colton Erica , Meyerson Howard , Anderson James M. 
Published: June 2005

AbstractThe host foreign body response ensues immediately following implantation of medical devices and prostheses. We have previously identified the role of macrophages in adhering to biomaterial surfaces and guiding the foreign body response while fusing into foreign body giant cells (FBGCs) and concentrating degradative and phagocytic activities. Despite their early and transient presence around implanted biomaterials, few studies have focused on the role of lymphocytes in the foreign body response and biocompatibility. To address this, an in vitro human lymphocyte/macrophage coculture system has been developed. Using this system, it has been shown that when lymphocytes are present during the initial adhesion of monocytes, the rate of monocyte adhesion and fusion is significantly increased (1,500 cells/mm2 and 60%, respectively) when compared to either no lymphocytes present (500 cells/mm2 adhesion and 0% fusion). Although lymphocytes adhered to the tissue culture polystyrene surface, 90% of the lymphocytes were associated with adherent macrophages. However, these cell–cell direct interactions were not necessary to influence macrophage adhesion or fusion as separating the two cell types by a Transwell insert still resulted in significantly increased levels of macrophage adhesion (p < 0.05 when compared to macrophage only cultures). Conversely, the presence of macrophages in Transwell experiments increased lymphocyte proliferation rates at all time points tested. These studies begin to detail the interactions between lymphocytes and macrophages in the absence of known antigen that appropriately relates to the scenarios experienced upon implantation of biomedical devices and the initiation of the foreign body response. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005