bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of inhomogeneous thin films of ZrO2 by the combined optical method and atomic force microscopy
Authors: Franta D. , Ohlídal I. , Klapetek P. , Pokorný P. , Ohlídal M. 
Published: September 2002

AbstractIn this paper results concerning the complete optical analysis of inhomogeneous ZrO2 films are introduced. The optical analysis of these films is carried out using the combined optical method based on interpreting experimental data corresponding to variable angle of incidence spectroscopic ellipsometry (VASE) and near‐normal incidence spectroscopic reflectometry (NNSR). The model of the ZrO2 films used for interpretation of the experimental data achieved using the combined method exhibits a continuous refractive index profile. It is shown that this model is satisfactory for treating the experimental data. Further, it is shown that all the parameters characterizing the model mentioned can be determined with high accuracy. By means of atomic force microscopy (AFM) it is found that the upper boundaries of the inhomogeneous ZrO2 films are slightly rough. The values of the basic statistical quantities characterizing this boundary roughness are evaluated using the AFM data. The optical inhomogeneity of the ZrO2 films studied is explained by the columnar structure of these films. Copyright © 2001 John Wiley & Sons, Ltd.
Selective catalytic reduction of NOx by methane over Co/ZrO2 catalysts
Authors: Hadjiivanov K. , Avreyska V. , Tzvetkov G. , Stefanov P. , Chupin C. , Mirodatos C. , Marinova Ts. 
Published: September 2002

AbstractThe effect of the preparation on the catalytic performances of Co/ZrO2 catalysts in the selective catalytic reduction of nitrogen oxides with methane was studied. The samples were prepared by grafting and impregnation with different solutions of cobalt salts. X‐ray photoelectron spectroscopy analysis showed that the cobalt oxidation state is 2+ in all samples. It was found that a high cobalt dispersion favours nitrogen selectivity, especially at temperatures below 350 °C. All samples show a maximum NO conversion in the temperature interval 300–350 °C, but the nitrogen selectivity decrease at this temperature range. The Fourier transform infrared spectroscopic studies showed that although the surface nitrates formed on bare zirconia are highly inert, the nitrates on cobalt particles fully interact with methane at 300 °C to produce an organic nitrogen‐containing deposit that is known to react with NOx to form nitrogen. Compared with the reference Co‐ZSM‐5 catalyst, the nitrates on Co/ZrO2 samples react with methane at a higher temperature, which accounts for their catalytic performances. Copyright © 2001 John Wiley & Sons, Ltd.
Morphogenesis of surface patterns and incorporation of redox‐active metals in mesoporous silicate molecular sieves
Authors: Yuan Z. Y. , Zhou W. , Zhang Z. L. , Liu J. Q. , Wang J. Z. , Li H. X. , Peng L. M. 
Published: September 2002

AbstractHierarchically ordered mesoporous metallosilicate MCM‐41 molecular sieves have been synthesized. The redox‐active metals Ti, V, Cr and Mn were incorporated in the framework, as characterized by various spectroscopic techniques. These materials have extraordinary morphologies in terms of their diverse and remarkable shapes and impressive surface patterns, such as centipede‐like, rope, vesicle and gyroidal spheroid, as revealed by transmission electron microscopy (TEM) images. The spatial relationship between the channel axis and the morphologies of the mesoporous silicates was investigated. The morphology formation of metallosilicates could be affected by the properties of the incorporated transition metal species. Copyright © 2001 John Wiley & Sons, Ltd.
Identification of hydrogen bond characterizations of isomeric 4Bpy and 2Bpy by STM
Authors: Xu Bo , Yin Shuxia , Wang Chen , Zeng Qingdao , Qiu Xiaohui , Bai Chunli 
Published: September 2002

AbstractWith submolecular resolution, scanning tunneling microscopy (STM) has been used extensively to study adsorption phenomena of organic molecules on surfaces. In this paper, we report a STM study of the isomeric compound of 4,4′‐bipyridyl (4Bpy) and 2,2′‐bipyridyl (2Bpy) co‐adsorbed with stearic acid on a highly oriented pyrolytic graphite (HOPG) surface. The 4Bpy and 2Bpy are isomeric compounds, and their only difference is the positions of the nitrogen atoms in each molecule. When Bpy molecules are mixed with stearic acid, the nitrogen atoms of Bpy can hydrogen bond with the COOH group of stearic acid, and hence the positions of the nitrogen atoms determine the hydrogen bond structure. It is observed that in the 4Bpy – stearic acid system the angle of the 4Bpy to the stearic acid molecular axis is ∼165°, whereas in the 2Bpy – stearic acid system the angle of the 2Bpy to the stearic acid molecular axis is ∼125°. The distances between two neighbouring ‘bright’ rows in an STM image are different in these two systems. Thus, by using this hydrogen bond method we can distinguish the 4Bpy molecule from its isomeric 2Bpy molecule. Furthermore, as reported previously, we observe the enantiomeric molecular patterns in both 4Bpy and 2Bpy systems. Copyright © 2001 John Wiley & Sons, Ltd.
Frictional properties of molecular thin films
Authors: Shi Bing , Lu Xinchun , Luo Jianbin , Chen Darong , Liang Hong 
Published: September 2002

AbstractIn this paper, we discuss the frictional behaviour of molecular thin films on a mica surface at a nanometre scale. Carbon 60 (C60)‐based macromolecules were synthesized experimentally. Analytical techniques such as Fourier transform infrared spectroscopy, UV–VIS spectroscopy and gel permeation chromatography were used to analyze the synthesized product. The Langmuir–Blodgett technique was used in making the macromolecules in the thin film on the mica surface. Atomic force microscopy and friction force microscopy were used for surface characterization. The properties, novel structures and their effects on frictional properties are discussed based on experiment results. It is found that the molecular thin films can be transferred onto the mica surface. These thin films possess significant tribological properties. Copyright © 2001 John Wiley & Sons, Ltd.
Detection of shear force with a piezoelectric bimorph cantilever for scanning near‐field optical microscopy
Authors: Shang Guangyi , Wang Chen , Lei Hening , Bai Chunli 
Published: September 2002

AbstractWe present a non‐optical shear force method to control the probe–sample distance for scanning near‐field optical microscopy (SNOM). In this system, the detection of shear force is accomplished by attaching a tapered fibre‐optic probe to a piezoelectric bimorph cantilever, which realizes the excitation and the detection simultaneously. The decrease in amplitude of the cantilever is observed when the probe approaches the sample and the shifts in resonance frequency are measured as a function of set‐point. The shear force images can be obtained reliably because the set‐point is >0.8. These results suggest that the system is reasonably sensitive to shear force and can be used easily for SNOM. Copyright © 2001 John Wiley & Sons, Ltd.
Quantitative X‐ray photoelectron spectroscopy study of enargite (Cu3AsS4) surface
Authors: Rossi A. , Atzei D. , Da Pelo S. , Frau F. , Lattanzi P. , England K. E. R. , Vaughan D. J. 
Published: September 2002

AbstractThe surface chemical state and composition of natural and synthetic enargite samples were characterized with X‐ray photoelectron spectroscopy (XPS). Freshly cleaved, powdered and ‘as received’ samples were analysed at liquid nitrogen temperature. For the natural ‘as received’ samples as well as for the natural and synthetic powdered samples the binding energies of Cu 2p3/2, As 3d5/2 and S 2p are consistently found at 932.5 ± 0.2, 43.9 ± 0.2 and 162.2 ± 0.2 eV, respectively. A second component of S 2p at 163.9 ± 0.2 eV is present and may be assigned to elemental sulphur. Freshly cleaved enargite samples showed binding energies of 43.2 and 161.3 eV, respectively, for As 3d5/2 and S 2p3/2. At the surface of crystals ‘as received’, an additional signal at ∽169 eV, referable to sulphate sulphur, is also present, as well as additional signals for Cu 2p3/2 (∽934 eV), and As 3d5/2 (∽45.5 eV). The thickness and the composition of this outer oxidized layer together with the composition of the interface beneath the film are calculated on the basis of a model developed for this purpose, taking into account the attenuation of the photoelectrons due to the contamination and the oxidized layer. An oxidized film of ∽0.5 nm is present at the surface of the ‘as received’ crystals whose composition was found to be ∽45% copper, 24% arsenic and 31% sulphur; hence, the oxidized layer appears to be enriched in arsenic compared with the bulk composition. The composition of the material beneath the oxidized layer was found to be enriched in copper and depleted in sulphur with respect to the bulk analysis. Any further study of the interaction of natural enargite samples with the environment has to take into account the existence of this thin outer layer. Copyright © 2001 John Wiley & Sons, Ltd.
Adsorbate‐catalyzed anodic dissolution and oxidation at surfaces in aqueous solutions
Authors: Kelber J. , Seshadri G. 
Published: September 2002

AbstractCertain adsorbates, particularly sulfur and iodine, present at submonolayer coverages catalyze anodic dissolution or oxidation at selected transition metal surfaces. No change in adsorbate surface coverage or oxidation state is observed during the dissolution process, indicating that the process is truly catalyzed by the adsorbed impurity. This allows enhanced dissolution to take place in environments entirely free of solvated forms of the impurity. In the case of iodine, the mechanism depends in part on the relative strength of iodine–metal vs. metal–metal bond strengths, but also depends on other factors that are as yet poorly understood. In the case of adsorbed sulfur, the effect is related to the ability of adsorbed sulfur to hinder the formation of an oxide layer via the complete dissociation of water at the solid surface. The relevance of these adsorbate‐catalyzed processes to intergranular stress corrosion cracking and semiconductor device processing are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
In‐depth characterization of screen‐printed electrodes by laser‐induced breakdown spectrometry and pattern recognition
Authors: Amador‐Hernández J. , Fernández‐Romero J. M. , Luque de Castro M. D. 
Published: September 2002

AbstractThe application of laser‐induced breakdown spectrometry (LIBS) and chemometrics [namely principal component analysis (PCA) and cluster analysis (CA)] is presented for the characterization of screen‐printed electrodes with in‐depth resolution. An Nd : YAG laser operating at the fundamental wavelength of 1064 nm was focused on the sample and the plasma emission was collected by a fibre‐optic bundle coupled to a spectrograph–charge‐coupled device system. The experimental variables were optimized for a satisfactory spatial characterization. The different zones of the screen‐printed electrode were studied (working electrode, reference electrode and electrical contacts) in order to identify both the composition and distribution of the layers deposited on the inert support for the construction of the electronic device. Carbon, gold, silver, platinum, palladium, titanium and aluminium were identified as major components. The use of pattern recognition techniques (PCA and CA) for the statistical treatment of the spectroscopy data obtained by LIBS proved to be a powerful tool for the rapid analysis of miniaturized multilayer electronic devices. Copyright © 2001 John Wiley & Sons, Ltd.
Corporate tournaments and executive compensation: Evidence from the U.K.
Authors: Conyon Martin J. , Peck Simon I. , Sadler Graham V. 
Published: September 2002

AbstractThis study tests the implications of tournament theory using data on 100 U.K. stock market companies, covering over 500 individual executives, in the late 1990s. Our results provide some evidence consistent with the operation of tournament mechanisms within the U.K. business context. Firstly, we find a convex relationship between executive pay and organizational level and secondly, that the gap between CEO pay and other board executives (i.e., tournament prize) is positively related to the number of participants in the tournament. However, we also show that the variation in executive team pay has little role in determining company performance. Copyright © 2001 John Wiley & Sons, Ltd.
Strategic reward systems: a contingency model of pay system design
Authors: Boyd Brian K. , Salamin Alain 
Published: September 2002

AbstractA limited number of studies have addressed the idea of ‘strategic’ reward systems—the matching of compensation systems to a firm's strategy. Prior research on this topic has been confined to U.S. firms, however, and a number of key questions remain unanswered. Using a sample of 917 employees from two large Swiss financial institutions, we found that pay systems are linked with divisional strategic orientation, but in a different form than prior studies. Additionally, we identify hierarchical position as an important variable in the tailoring of reward systems. Hierarchy has a significant main effect on pay plan design, and an interactive effect with strategic orientation. Copyright © 2001 John Wiley & Sons, Ltd.
From gap gazing to promising cases: Moving toward equity in urban education reform*
Authors: Rodriguez Alberto J. 
Published: September 2002

AbstractA case analysis of the Miami‐Dade Urban Systemic Initiative is presented in this article, citing this initiative as one of the sites with the greatest promise for affecting equity issues. Using a grounded‐theory methodological approach, a general framework for systemic reform was developed as a tool to examine the particulars of systemic reform initiatives and their potential to impact the teaching and learning of science and mathematics in diverse school contexts. It was found that to better understand the effectiveness of systemic reform initiatives requires answering two basic questions: What is the (pedagogical and ideological) systemic conceptual clarity guiding the reform efforts? And, what is the operational approach? Once answers to these questions are found, it becomes easier to explore how key officials are implementing or not implementing other aspects of systemic reform. The article also explains why less attention should be given to student outcomes (based on standardized tests) as the main indicator of success in systemic reform. Instead, it is proposed that insights gained from studying the particulars of promising initiatives can help others stimulate systemic reform in their own contexts, especially in urban contexts, which usually have few resources and a large population of students who are traditionally underserved. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 1115–1129, 2001
Rethinking diversity in learning science: The logic of everyday sense‐making
Authors: Warren Beth , Ballenger Cynthia , Ogonowski Mark , Rosebery Ann S. , Hudicourt‐Barnes Josiane 
Published: September 2002

AbstractThere are many ways to understand the gap in science learning and achievement separating low‐income, ethnic minority and linguistic minority children from more economically privileged students. In this article we offer our perspective. First, we discuss in broad strokes how the relationship between everyday and scientific knowledge and ways of knowing has been conceptualized in the field of science education research. We consider two dominant perspectives on this question, one which views the relationship as fundamentally discontinuous and the other which views it as fundamentally continuous. We locate our own work within the latter tradition and propose a framework for understanding the everyday sense‐making practices of students from diverse communities as an intellectual resource in science learning and teaching. Two case studies follow in which we elaborate this point of view through analysis of Haitian American and Latino students' talk and activity as they work to understand metamorphosis and experimentation, respectively. We conclude with a discussion of the implications of this new conceptualization for research on science learning and teaching. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 529–552, 2001
Isolation and sequence of the MIG1 homologue from the yeast Candida utilis
Authors: Delfin Julieta , Perdomo Walmer , García Bianca , Menendez Javier 
Published: September 2002

AbstractThe Mig1p repressor from the food yeast Candida utilis has been isolated using a homologous PCR hybridization probe. This probe was amplified with two sets of degenerate primers designed on the basis of highly conserved motifs in the DNA‐binding region (zinc‐finger domain) from yeast Mig1p and fungi CreA repressors. The cloned gene was sequenced and found to encode a polypeptide of 345 amino acids which shows significant identity with other yeast and fungus repressors in the DNA‐binding domain and also with the yeast Mig1 proteins in the C‐terminal region (effector domain). The MIG1 repressor gene from C. utilis was able to complement functionally the mig1 mutation of S. cerevisiae. The sequence presented here has been deposited in the EMBL data library under Accession No. AJ277830. Copyright © 2001 John Wiley & Sons, Ltd.
Lifetime semen production in a cheetah (Acinonyx jubatus)
Authors: Durrant Barbara S. , Millard Susan E. , Zimmerman Dawn M. , Lindburg Donald G. 
Published: September 2002

AbstractLifetime semen production data provide valuable insight into a species’ natural history and biology as well as information about the potential fertility of males at various life stages. An understanding of the ages of sexual maturity, peak sperm production, and gonadal senescence will contribute to the design of species management plans for captive, free‐ranging, and reintroduced populations of exotic animals. To describe these life stages in the cheetah, semen was collected biweekly for 13 years from a solitary male beginning at 3 years of age. The 338 ejaculates were obtained noninvasively by artificial vagina. Ejaculate volume and sperm motility score, concentration, and normal morphology were recorded. A sperm quality index incorporating all five semen parameters was calculated to facilitate ejaculate comparisons. Polynomial regression analysis revealed a significant effect of age on volume, which increased throughout the animal’s lifetime except for a reduction between ages 10 and 12. Concentration was also significantly affected by age and increased from the age of 3 to the age of 10, then decreased. The sperm quality index revealed a significant effect of age as it increased from age 3 to age 8, then declined as the male grew older. The cheetah did not reach peak semen production until age 8 and continued to produce good quality semen for several more years. These data were somewhat unexpected, given the average cheetah life expectancy of approximately 7 years. Zoo Biol 20:359–366, 2001. © 2001 Wiley‐Liss, Inc.
BIFURCATION, BURSTING AND SPIKE GENERATION IN A NEURAL MODEL
Authors: GOVAERTS W. , DHOOGE A. 
Published: September 2002

Bursting is an important behavior pattern of nerve cells and in mathematical models it is often related to bifurcations. However, the onset of bursting and the birth of new spikes are also possible without any bifurcation. We present a numerical study of a model of Plant which exhibits a periodically bursting behavior in a relevant range of two parameters. In this two-dimensional range the behavior changes continuously, except for a number of tiny regions where spikes are born or die. These islands are extensions of bifurcation islands. It appears that the generation of spikes can be related to local extrema of the periods of the bursting periodic orbits. This allows to detect the birth of spikes also in parameter regions where no bifurcations occur. From a biological point of view the average instantaneous spike frequency is probably the most important output variable of a neuron. We show that in the Plant model (in contrast to some other models) this frequency is essentially determined by the number of spikes in a burst.
Toward an Aposynthesis of Topic Continuity and Intrasentential Anaphora
Authors: Miltsakaki Eleni 
Published: September 2002

The problem of proposing referents for anaphoric expressions has been extensively researched in the literature and significant insights have been gained through the various approaches. However, no single model is capable of handling all the cases. We argue that this is due to a failure of the models to identify two distinct processes. Drawing on current insights and empirical data from various languages we propose an aposynthetic 1 model of discourse in which topic continuity, computed across units, and focusing preferences internal to these units are subject to different mechanisms. The observed focusing preferences across the units (i.e., intersententially) are best modeled structurally, along the lines suggested in centering theory. The focusing mechanism within the unit is subject to preferences projected by the semantics of the verbs and the connectives in the unit as suggested in semantic/pragmatic focusing accounts. We show that this distinction not only overcomes important problems in anaphora resolution but also reconciles seemingly contradictory experimental results reported in the literature. We specify a model of anaphora resolution that interleaves the two mechanisms. We test the central hypotheses of the proposed model with an experimental study in English and a corpus-based study in Greek. 1 “Aposynthesis” is a Greek word that means “decomposition,” that is, pulling apart the components that constitute what appears to be a uniform entity.
Essentialism and Folkbiology: Evidence from Brazil
Authors: Sousa Paulo , Atran Scott , Medin Douglas 
Published: September 2002

Abstract
Experimental results in reference to Brazilian children and adults are presented in the context of current discussions about essentialism and folkbiology. Using an adoption paradigm, we replicate the basic findings of a previous article in this journal concerning the early emergence in children of a birth-parent bias (Atran et al. 2001). This cognitive bias supports the claim that causal essentialism cross-culturally constrains the reasoning about the origin, development and maintenance of the characteristics and identity of living kinds. We also report some intriguing differences with earlier findings that speak to theoretical and methodological issues of cultural relativity.