bluuebunny/crossref_metadata_2025 huggingface dataset:
CONTEXT AWARE PERSONAL INFORMATION AGENTS
Authors: LLUÍS ARCOS JOSEP , PLAZA ENRIC
Published: September 2002

We present a society of personal information agents that work for a community of users and that are aware of the physical and social context of their users. We show how context-awareness is a feature that allows the agents to improve their performance when they work with limited resources in information spaces with a large amount of information. The use of context information allows the agents to focus their information search and, as a result of this, increase the quantity and quality of information delivered to the user. Moreover, we propose an implemented agent architecture with context-aware capabilities. We discuss this architecture in detail, focusing on the capability of exploiting the windows of opportunity provided by the awareness of the users' activity. The agents use these windows of opportunity to furnish the user with information and advice in the situation where it can be most useful. In particular, we show how context-aware information agents can assist a community of attendees to big conferences and fairs. In this application, an information agent gathers relevant information based on a model of specific interests of a user. Given the multiplicity of interesting events, and their distribution in time and space, an information agent has to deliver the gathered information in a few hours and comply to the schedule constraints. Finally, we report some experimentation results to illustrate how context-awareness improve the service a society of information agents provides to a community of users in the conference application.
BioMAS: A MULTI-AGENT SYSTEM FOR GENOMIC ANNOTATION
Authors: DECKER KEITH , KHAN SALIM , SCHMIDT CARL , SITU GANG , MAKKENA RAVI , MICHAUD DENNIS
Published: September 2002

The explosive growth in genomic (and soon, expression and proteomic) data, exemplified by the Human Genome Project, is a fertile domain for the application of multi-agent information gathering technologies. Furthermore, hundreds of smaller-profile, yet still economically important organisms are being studied that require the efficient and inexpensive automated analysis tools that multi-agent approaches can provide. In this paper, we discuss the use of DECAF, a multi-agent system toolkit based on RETSINA and TAEMS, to build reusable information gathering systems for bioinformatics. We will cover why bioinformatics is a classic application for information gathering, how DECAF supports it, and several extensions that support new analysis paths for genomic information.
MOMIS: EXPLOITING AGENTS TO SUPPORT INFORMATION INTEGRATION
Authors: CABRI G. , GUERRA F. , VINCINI M. , BERGAMASCHI S. , LEONARDI L. , ZAMBONELLI F.
Published: September 2002

Information overloading introduced by the large amount of data that is spread over the Internet must be faced in an appropriate way. The dynamism and the uncertainty of the Internet, along with the heterogeneity of the sources of information are the two main challenges for today's technologies related to information management. In the area of information integration, this paper proposes an approach based on mobile software agents integrated in the MOMIS (Mediator envirOnment for Multiple Information Sources) infrastructure, which enables semi-automatic information integration to deal with the integration and query of multiple, heterogeneous information sources (relational, object, XML and semi-structured sources). The exploitation of mobile agents in MOMIS can significantly increase the flexibility of the system. In fact, their characteristics of autonomy and adaptability well suit the distributed and open environments, such as the Internet. The aim of this paper is to show the advantages of the introduction in the MOMIS infrastructure of intelligent and mobile software agents for the autonomous management and coordination of integration and query processing over heterogeneous data sources.
OPTIMAL BIDDING IN MULTIPLE CONCURRENT AUCTIONS
Authors: SHEHORY ONN
Published: September 2002

In the face of multiple electronic sales sites, buyers can benefit from considering multiple opportunities and devising their purchase strategy to reduce risk and increase expected utility. However, human users cannot approach and rapidly monitor multiple sites. In particular, sites where prices change dynamically such as auction sites pose a major difficulty for human concurrent activity. Even without concurrency, the majority of human users do not have the ability or the resources to compute optimal purchase decisions. Such activities can be performed by computational agents. In this paper, we present mechanisms that allow agents to perform purchases on behalf of users. In particular, we devised methods that allow an agent that faces multiple dynamic sales sites to compute bids that optimize the expected utility of the user, or instead manage the winning probability of the purchase.
PROBLEM-SOLVING METHODS AND COOPERATIVE INFORMATION AGENTS
Authors: GOMEZ MARIO , PLAZA ENRIC , ABASOLO CHEMA
Published: September 2002

Cooperative Information Agents and modern information systems in general have to access large amounts of information distributed across multiple heterogeneous sources. A great challenge of such systems is to evolve by adding new information sources or adapting the existing components for different domain knowledge. We propose the [Formula: see text] framework as a methodology to build Information Agents by reusing a library of problem-solving components that are defined in a domain-independent manner. Moreover, the [Formula: see text] language is used as an Agent Capability Description Language (ACDL) suitable to configure an agent-based application.

From this approach, a new application is built by linking the components of the library with a particular domain and a collection of heterogeneous information sources. Adaptability and dynamic configuration of such a system is achieved by reasoning about the [Formula: see text] specification of the agent capabilities. Independence of the domain and semantic interoperability are achieved by using ontologies and bridges (mappings between ontologies), while independence from the information sources is based again in the use of ontologies to overcome semantic heterogeneity and wrappers to achieve syntactic interoperability.
VIRTUAL ENTERPRISES AND WORKFLOW MANAGEMENT AS AGENT COORDINATION ISSUES
Authors: RICCI ALESSANDRO , OMICINI ANDREA , DENTI ENRICO
Published: September 2002

Agents and multiagent systems (MAS) have already proved suitable for dealing with the complexity of today B2B application scenarios. Application environments such as virtual enterprises (VE) and inter-organizational workflow management systems (WfMS) specially call for the integration of heterogeneous resources, services, and processes. In this article, we first recognize VE and workflow management as agent coordination problems, then discuss how objective coordination — that is, coordination from outside agents — can help to model VE and WfMS. Finally, we show the impact of an agent coordination infrastructure like [Formula: see text] on the engineering of highly dynamic VE and WfMS, by discussing a simple case study.
THE SOCIAL NATURE OF INFORMATION AND THE ROLE OF TRUST
Authors: CASTELFRANCHI CRISTIANO
Published: September 2002

In this paper, I claim that "information" is a social construct, is created and tailored on purpose by somebody for somebody else or collectively, accepted, believed, or propagated through social interactions. In particular, I argue about the essential social nature of several crucial aspects of information in IT and specifically in relation to Information Agents. After situating this view of information within the broader perspective of Social Artificial Intelligence — the new AI paradigm — I analyize the intrinsic social aspects of information ontology, search and access, presentation, overload, credibility and sources, value. The issue of real "collaboration" in providing information deserves special attention and I introduce our theory of over-help and of the ability to provide something different from what is requested in order to satisfy the real need beyond the request. In the second part, I focus on the crucial role of trust (an intrinsically social and cognitive notion) for dealing with information and sources especially on the web. My objective is to claim that: if information per se is a social construct, then its technology should be socially designed and integrated, and that machines must be involved in real social relationships because they have to mediate them among humans. It is necessary incorporating some part of this social knowledge and capability in the information technology itself, especially in adaptive and interacting "agents" and MAS.
COOPERATIVE INFORMATION AGENTS: BEST PAPERS OF CIA 2001 GUEST EDITORS' INTRODUCTION
Authors: KLUSCH MATTHIAS , ZAMBONELLI FRANCO
Published: September 2002

This special issues contains a selection of the best papers presented at the Fifth International Workshop on Cooperative Information Agents, held in Modena, Italy, September 6–8, 2001.

Information agent technology has become one of the major key technologies for the Internet and the World Wide Web.2,5 It mainly emerged as a response to the challenges of cyberspace from both the technological and human user perspective. Development of information agents requires expertise from different research disciplines such as Artificial Intelligence (AI), advanced databases and knowledge base systems, distributed information systems, information retrieval, and Human Computer Interaction (HCI).

The Fifth International Workshop on Cooperative Information Agents (CIA) continued the tradition by capturing the intrinsic interdisciplinary nature of the above research area by calling for contributions from different research communities, and by promoting open and informative discussions on all related topics. In keeping with tradition, the workshop featured a sequence of regular and invited talks of excellence given by leading experts in the field. As a novelty, the CIA 2001 workshop issued two awards for best paper and best system innovation to acknowledge particularly significant advances in research and development respectively, in the area of information agents. An extended version of the awarded best paper authored by Onn Shehory is included in this special issue.
HYDRATE MODEL OF THE EQUILIBRIUM DNA–WATER SYSTEMS
Authors: OSTROVSKII VICTOR E. , KADYSHEVICH ELENA A.
Published: September 2002

A hydrate model for the DNA– H2O system is proposed. For the notions developed, available data on a tendency of H2O molecules to form structured hydrates containing atomic groups, molecules, or atoms housed within the structural cavities formed by H-bonded H2O molecules are used. It is shown that the large and small cavities of the hydrate structure II are in close geometric agreement with N-bases and deoxyribose and with other atomic groups of DNA molecules, respectively. On the basis of the model proposed and with the Watson–Crick base-pairing scheme, the number of pairs of N-bases per helix turn (11.25), the density (1.161 g/cm3), and the helix step (0.567 nm) for the quasi-equilibrium DNA (RNA)–water system are computed, the last value nearly coinciding with the well-known alpha-helix step in the protein secondary structure (5.44 nm). Assumptions on the phenomenology of some stages of mitosis are presented.
NANOSCIENCE ADVANCES IN THE UK IN SUPPORT OF NANOTECHNOLOGY
Authors: LEACH RICHARD K. , BLUNT LIAM , CHETWYND DEREK G. , YACOOT ANDREW
Published: September 2002

There is little doubt that nanotechnology will revolutionise peoples' approaches to areas as diverse as the structure of materials, production engineering, biotechnology and medicine. Currently there are a number of companies that are exploiting micro- and nanotechnology, mainly using a top–down approach, i.e., through miniaturisation. As new products are created from the new technologies there must be methods, developing in parallel, for ensuring product reliability and quality assurance. It is asserted that this can only be achieved through the development of a metrology infrastructure. This paper will describe some of the advances that have been made in the UK in developing such an infrastructure.
SYNTHESIS OF AMORPHOUS SiOx NANOSTRUCTURES
Authors: LAO J. Y. , WEN J. G. , WANG D. Z. , REN Z. F.
Published: September 2002

Various amorphous SiO x nanotube structures nucleated by GeOx nanoparticles were synthesized by thermal evaporation method. The presence of Ge does not only nucleate the growth of the SiO x nanomaterials, but also dopes them. The nanostructure morphology is affected by the substrate temperature, source temperature and GeO x vapor density through their effect on the size and lifetime of the nucleation center. In general, low substrate temperature promotes the formation of the nanotube bundle structure with 2–3% atomic ratio of Ge doping, and high temperature produces Ge-free much less bundled nanotubes.
SYNTHESIS OF WC–Co NANOCOMPOSITES BY USING POLYMERS AS IN SITU CARBON SOURCE
Authors: KRISHNA B. VAMSI , GAGANPREET K. V. , BHUNIA H.
Published: September 2002

The WC–Co nanocomposites were synthesized by using a polymer precursor such as polyacrylonitrile, which severs as an in situ carbon source. The WC–Co nanocomposites formed are characterized by X-ray diffraction and electron microscopy. Nearly pure WC–Co nanocomposites with a particle size in the range of 60–80 nm have been obtained. The use of H2 atmosphere enhanced the carbide formation and in turn reduced the reaction time (at high temperature). The phase purity of the products is strongly influenced by the processing conditions such as the firing temperature, time and atmosphere. This suggests that the process parameters have to be optimized before scaling up the process for commercial production.
SHAPE CONTROL OF Bi2S3 NANOPARTICLES
Authors: PAN DENGYU , ZHANG SHUYUAN , LI GONGPU , CHEN YIQING , HOU J. G.
Published: September 2002

Bi 2 S 3 nanocrystals with different shapes were synthesized via a simple solventothermal route. Nanorods and nanotubes can be obtained by changing reaction temperature. In the presence of surfactant, hollow nanospheres can be produced. The nanocrystals were characterized by X-ray powder diffraction and transmission electron microcopy. The growth mechanisms were discussed.
COMBINATORIAL APPROACHES FOR FUNCTIONAL NANOSTRUCTURE FABRICATION
Authors: GU NING , HUANG LAN
Published: September 2002

With the development of microfabrication techniques and nanoscale science and technology, functional nanostructures and nanodevices have been the hot-points concerned by all scientific and technological circles. This paper presents a series of our efforts on making functional nanostructures for fabrication of nanodevices, especially for prototype single electron devices (SEDs). A necessary computer simulation for explaining the electrical properties of this prototype SED is also included.
X-ray powder diffraction analysis of a nonlinear optical material N-(p-methoxy benzoyl)-N′-(p-methyl phenyl) thiourea
Authors: Zhou Weiqun , Xie Chao , Jin Zheng , Jin Zong-ming
Published: September 2002

A nonlinear optical material, N-(p-methoxy benzoyl)-N′-(p-methyl phenyl) thiourea (C16H16N2O2S), has been characterized by X-ray powder diffraction. Experimental values of 2θ corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 94 observed reflections with 2θ up to 66° are reported. The powder diffraction data and the figure-of-merit are reported. The least-squares refined unit cell parameters are a=25.3291(3) Å, b=11.9478(1) Å, c=10.1407(4) Å, β=103.10(2)°, V=2988.97(6) Å3, Z=8, Dx=1.335(0) g/cm3, with space group P21(4).
X-ray powder diffraction analysis of a nonlinear optical material N-(p-methoxy benzoyl)-N′-(o-methyl phenyl) thiourea
Authors: Zhou Weiqun , Zhang Zhenjiang , Jin Zheng , Jin Zong-ming
Published: September 2002

A nonlinear optical material, N-(p-methoxy benzoyl)-N′(o-methyl phenyl) thiourea (C16H16N2O2S), has been characterized by X-ray powder diffraction. Experimental values of 2θ corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 90 observed reflections with 2θ up to 88° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The least-squares refined unit cell parameters are a=26.7079(3) Å, b=6.7995(9) Å, c=19.2845(1) Å, β=121.39(4), V=2989.42(3) Å3, Z=8, Dx=1.334(8) g/cm3, space group P2(3).
Determination of amorphous phase levels in Portland cement clinker
Authors: Suherman Phe Man , van Riessen Arie , O’Connor Brian , Li Deyu , Bolton Dick , Fairhurst Hans
Published: September 2002

The existence of glass or amorphous component in Portland cement clinker has been questioned for a long time. However, besides the crystalline phases, there are reports in the literature of noncrystalline material in cement clinker, which is considered to be the residue of the melt that has failed to crystallize. Absolute phase abundances were determined in this study by Rietveld refinements with laboratory X-ray data, using both internal and external phase composition standards. The results clearly demonstrate the existence of an amorphous component in Portland cement clinker. The presence of an amorphous component was also apparent from diffraction data for clinker from which the silicate phases had been chemically removed, using both laboratory X-ray and synchrotron radiation patterns.
High-precision parallel-beam X-ray system for high-temperature diffraction studies
Authors: Mitsunaga Toru , Saigo Mari , Fujinawa Go
Published: September 2002

A recently developed Rigaku parallel-beam X-ray diffraction system equipped with a parabolic graded-multilayer mirror in the incident beam and a parallel-slits analyzer in the diffracted beam was used for precision high-temperature diffraction studies. The lattice parameters a and c of α-Al2O3 at room temperature and up to 1473 K were determined with precision in the range of 0.6–7.3×10−5. The thermal expansion coefficients for a and c agreed with literature values to better than 3%. The system was used successfully also to determine the Debye characteristic temperature of Si and to study structural phase transition of LaCoO3 from rhombohedral at room temperature to cubic at 1700 K.
Structure determination from powder diffraction data of a new layered ammonium lanthanum sulfate, β-(NH4)La(SO4)2
Authors: Bénard-Rocherullé P. , Tronel H. , Louër D.
Published: September 2002

A new variety of ammonium lanthanum sulfate, β-(NH4)La(SO4)2, was synthesized hydrothermally. The crystal structure was solved ab initio from powder diffraction data collected using a conventional X-ray source. The powder diffraction pattern was indexed by the successive dichotomy method: The symmetry is monoclinic, space group Pn, cell dimensions a=6.9365(4) Å, b=9.0055(5) Å, c=5.4541(4) Å, β=90.672(8)°, V=340.68(3) Å3 and Z=2 [M20=65, F30=124(0.0071,34)]. Direct methods were used for structure solution, and refinement of the atomic coordinates was carried out by the Rietveld method (RF=0.061, Rwp=0.099). The structure contains anionic layers built from lanthanum atoms ninefold coordinated to monodentate and bidentate sulfate oxygen atoms. Ammonium groups, which provide hydrogen bonds, are located between the layers. The crystal structure contrasts with that of the α phase, which is less dense by a factor of 4.4%.
Powder XRD study of Ba4Eu3F17: A new anion rich fluorite related mixed fluoride
Authors: Achary S. N. , Patwe S. J. , Tyagi A. K.
Published: September 2002

The compound Ba4Eu3F17 was prepared by heating pre-dried BaF2 and EuF3 (4:3) at 800 °C for 8 h in static vacuum. The colorless polycrystalline product obtained was characterized by Rietveld refinement of the observed powder diffraction data with a starting model of Ba4Y3F17. The title compound Ba4Eu3F17 crystallizes in rhombohedral lattice with lattice parameters, a=11.1787(4) and c=20.5789(10) Å, Z=3 (Space group R 3, No. 148). The Ba4Eu3F17 structure can be described as an ordered anion-rich fluorite type structure with the formation of Eu6F37 clusters. There are two crystallographically distinct Ba (CN=10, 11) and one distinct Eu (CN=8). The typical Ba(1)–F, Ba(2)–F, and Eu–F bond lengths range from 2.56 to 2.83 Å, 2.54 to 3.25 Å, and 2.24 to 2.49 Å, respectively. The salient feature of the structure is that the EuF8 polyhedra share their corner to form a cubo-octahedron of fluoride ions. The cubic BaF8 polyhedra of BaF2 are modified to Ba(1)–F10 and Ba(2)–F11 polyhedra in this structure. The cubo-octahedron encloses extra fluorine F(8) inside it.
Tetragonal low-temperature phase of MgCr2O4
Authors: Ehrenberg H. , Knapp M. , Baehtz C. , Klemme S.
Published: September 2002

Magnesiumchromite, MgCr2O4, undergoes a structural transition from a cubic spinel structure [space group Fd3m, a=8.32768(4) Å at 16 K] into a tetragonal distorted structure [space group I41/amd, a=5.89199(5) Å, c=8.31677(8) Å at 10 K], isotypic with Hausmannite, Mn3O4. This phase transition is translationengleich and takes place very close or at the antiferromagnetic ordering temperature.
The effect of the partial substitution of sulfur on the structural and microstructural properties of selenium
Authors: Heiba Z. K. , El-Den M. B. , El-Sayed Karimat
Published: September 2002

Samples of amorphous Se, SSe40, SSe30, and SSe20were synthesized and were then crystallized by annealing at 373 K for 5, 20, and 120 mins. The results showed that the changes in the structural and microstructural parameters for samples SSe40, and SSe30are different from those of sample SSe20. These discrepancies are being discussed in terms of the peak shifts in both the amorphous and crystalline state, the percentage of sulfur compositional variations, and finally in terms of the probable site occupancy of the sulfur atoms in the selenium structure.
Analysis of kaolinite/chrysotile mixtures by ashing and x-ray diffraction
Authors: Verkouteren Jennifer R. , Windsor Eric S. , Conny Joseph M. , Perkins Robert L. , Ennis J. Todd
Published: September 2002

A simple ashing procedure for a mixture containing kaolinite and chrysotile is described that converts kaolinite to amorphous metakaolinite while retaining the diffraction intensity of chrysotile. This ashing procedure removes the X-ray diffraction (XRD) pattern overlap between kaolinite and chrysotile that can interfere with the analysis of even high concentrations of chrysotile. Samples are ashed at 460 °C in a muffle furnace for 40 h to completely convert kaolinite to metakaolinite. The complete conversion of 1 g of kaolinite under these conditions was determined for two standard kaolinite samples from Georgia, KGa-1 and KGa-2. Two of the most common types of commercial chrysotile, long-fiber Canadian and short-fiber Californian chrysotile, are demonstrated to retain diffraction intensity after ashing at 460 °C. Both chrysotile samples have the same integrated intensity for the (002) reflection prior to ashing, although the peak breadths for the two samples are quite different. Ashing at 480 and 500 °C reduces the diffraction intensities of both chrysotile samples by 15%, and broadens the peaks by approximately 3%. Using the prescribed ashing procedure and x-ray diffraction with an internal corundum standard, two kaolinite-bearing building materials containing chrysotile near 0.01 mass fraction were analyzed. The ashing procedure has additional advantages in reducing some samples to powders and removing volatile components, thereby eliminating some sample preparation procedures and concentrating any chrysotile present in the sample. The removal of volatile components improves the sensitivity of XRD analysis to concentrations below 0.01 mass fraction chrysotile.
Modeling of hP3 intermetallics in space group P-3m1: Calculated powder patterns from CRYSTMET®X-ray cell data andab initiocoordinates
Authors: Le Page Y. , Rodgers John R. , White Peter S.
Published: September 2002

There are 39 CRYSTMET®entries in the hexagonal space group P-3m1 (164) reporting both distinct pure phase compounds and atomic coordinates. Having the same Wyckoff positions in the same space group as the C6 structure type, all are isopointal with it. The range of observedc/avalues extends from about 0.65 to 1.83. Three types are distinguished: Layered materials with CdI2type, the CeCd2type which is a slight distortion of the hexagonal AlB2type, and the intermediate EuGe2type made of the materials AuTe2, BaSi2, EuGe2, and SrGe2.Ab initiomodeling of the 26 entries with CdI2and EuGe2type and atomic coordinates reproduces convincingly both theirc/aaxial ratios andzcoordinates. For CoO2and SiTe2, bothc/aandzdeviate to a degree from the reported values, indicating that those materials should be reexamined for superstructures, stoichiometry, etc.Ab initiomodeling of the 11 cell-and-type entries with CdI2type and no coordinates in CRYSTMET reproduced convincingly their reported axial ratios. The X-ray cell data and theab initiozcoordinates were then used in the production of reliable calculated powder patterns for CoTe2, CrSe2, HfS2, HfSe2, HfTe2, NbTe2, SnSe2, VS2, VTe2, ZrS2, and ZrTe2. All 11 patterns have been inserted in the intense diffraction line search system of CRYSTMET operated under the Materials Toolkit. Comparison of calculated patterns for SnSe2and ZrTe2with experimental entries in the PDF exposes the complementarity of calculated and experimental powder patterns and suggests that JCPDS pattern #15-223 should be reinterpreted in terms of the CdI2structure type. The CeCd2⇔AlB2type transformation is modeled and discussed on YCd2using bothab initiomethods and a hard-sphere model. Forz<0.45, theab initiosolution is identical with that from the hard-sphere model while a quantum regime is predicted in the small region 0.45<z<0.467 beyond which YCd2abruptly transforms to the AlB2type. In spite of the new understanding gained, this modeling fell slightly short of allowing calculation ofzvalues and powder patterns for the materials CaHg2, DyHg2, ErCd2, GdHg2, HoCd2, HoHg2, LuCd2, NdCd2, SmHg2, TbCd2, and TbHg2with no coordinates in CRYSTMET.
Improved powder diffraction patterns for synthetic paranatisite and natisite
Authors: Ferdov S. , Kostov-Kytin V. , Petrov O.
Published: September 2002

Synthetic analogues of the minerals natisite and for the first time of paranatisite were prepared hydrothermally at 200 °C in the system Na2O–TiO2–SiO2–H2O. The obtained powder x-ray diffraction (XRD) patterns were interpreted by the Powder Data Interpretation (PDI) software package. As a result improved indexing and unit cell parameters refinements of these two phases were achieved. Synthetic natisite is tetragonal, space group—P4/nmm, a=0.649 67(8) nm, c=0.508 45(11) nm, V=0.214 50(10) nm3, Z=2, Dcal=3.13 g.cm−1, F30=37.48, M20=52.79. Synthetic paranatisite is orthorhombic, space group—Pmma, a=0.983 86(29) nm, b=0.919 23(19) nm, c=0.481 84(12) nm, V=0.435 78(19) nm3, Z=1, Dcal=3.01 g.cm−1, F30=16.42, M20=29.21.
Crystal structures and reference diffraction patterns of BaSrR4O8
Authors: Wong-Ng W. , Kaduk J. A. , Dillingham J.
Published: September 2002

The structure of BaSrR4O8 (where R=La, Nd, Sm, Gd, Eu, Dy, Ho, Y, Er, Tm, Yb, and Lu) has been investigated, and the X-ray reference patterns of these compounds have been prepared using the Rietveld refinement technique. BaSrR2O4 are isostructural to BaR2O4, which have the CaFe2O4 structure type (orthorhombic, Pnam). The cell parameters of these compounds (R=Lu to La) range from 10.125 04(10) to 10.5501(8) Å for a, 3.362 49(3) to 3.692 04(24) Å for b, 11.846 91(13) to 12.5663(9) Å for c, and 403.33 to 489.47 Å3 for V, respectively. There is a linear relationship between V and the Shannon ionic radius of R. Unlike the BaR2O4 compositions (R=Tm, Lu, and Yb), which produced a mixture of Ba3R4O9 and unreacted lanthanide oxides, single-phase BaSrTm4O8, BaSrLu4O8, and BaSrYb4O8 were successfully prepared.
X-ray quantitative analysis of the phases developed upon air annealing of ZnSe, CdSe, and CdS semiconductors
Authors: Heiba Z. K.
Published: September 2002

The phases developed upon annealing of ZnSe, CdSe, and CdS semiconductors in air are investigated applying X-ray qualitative and quantitative phase analysis. The compositions of the thermally grown oxides over the 373–773 K temperature range are found to be ZnO and ZnSeO3 for ZnSe, CdSeO3 for CdSe and CdSO4 and Cd3O2SO4 for CdS. The percentage phase abundance of each phase is determined at each temperature applying a standardless method. At all temperatures, the oxides are predominantly ZnO with about 10% ZnSeO3 at 773 K in case of ZnSe and CdSO4 with about 9% Cd3O2SO4 at 773 K in case of CdS. The rate of oxidation with temperature is found to be nonlinear for the three chalcogenides. CdS is found to be more resistible for oxidation than CdSe and ZnSe.
X-ray powder diffraction analysis of ±-fenoprofen calcium dihydrate
Authors: Tobien Ailette Aguila , Varlashkin Peter
Published: September 2002

The current JCPDS powder pattern for the racemic compound fenoprofen calcium dihydrate (card No. 44-1790) is unindexed. Previously we reported the single crystal data, determined at −100 °C, for this material (Zhu et al., 2001). Using 2θ values obtained from a powder pattern spiked with internal standards, we indexed the room temperature powder pattern. The resulting unit cell values for the monoclinic P21/n cell are a=19.018 Å, b=7.738 Å, c=19.472 Å, β=91.66°.
Thermal atomic displacement parameters of SrO
Authors: Bashir J. , Khan Rao Tahir A. , Butt N. M. , Heger G.
Published: September 2002

The atomic displacement parameters of individual ions in SrO have been determined from the Rietveld analysis of high-resolution powder neutron diffraction data. As the neutron velocity is smaller than the sound velocity in SrO, the intensity data was not corrected for the effect of thermal diffuse scattering. The room temperature value of overall isotropic thermal displacement parameters wasB=0.57(2) Å2; which corresponds to Debye temperature, Θ of 242(4) K. The results are compared with experimental and theoretical estimates.
Rietveld refinement of a triclinic structure for synthetic Na-birnessite using synchrotron powder diffraction data
Authors: Post Jeffrey E. , Heaney Peter J. , Hanson Jonathan
Published: September 2002

Rietveld refinement using synchrotron powder X-ray diffraction data revealed that the crystal structure of synthetic Na-birnessite is triclinic (C1), not monoclinic as was previously reported. The Mn–O octahedra have elongated axial bonds, consistent with Jahn–Teller distortion resulting from partial occupancy by Mn3+. Mean Mn–O distances indicate that Mn sites are ∼2/3 Mn4+ and ∼1/3 Mn3+. The interlayer Na cations and H2O molecules occupy a split site that shows evidence of considerable disorder.
Drug-Induced Long-QT Syndrome Associated With a Subclinical
SCN5A
Mutation
Authors: Makita Naomasa , Horie Minoru , Nakamura Takeshi , Ai Tomohiko , Sasaki Koji , Yokoi Hisataka , Sakurai Masayuki , Sakuma Ichiro , Otani Hideo , Sawa Hirofumi , Kitabatake Akira
Published: September 2002

Background—

Subclinical mutations in genes associated with the congenital long-QT syndromes (LQTS) have been suggested as a risk factor for drug-induced LQTS and accompanying life-threatening arrhythmias. Recent studies have identified genetic variants of the cardiac K
+
channel genes predisposing affected individuals to acquired LQTS. We have identified a novel Na
+
channel mutation in an individual who exhibited drug-induced LQTS.

Methods and Results—

An elderly Japanese woman with documented QT prolongation and torsade de pointes during treatment with the prokinetic drug cisapride underwent mutational analysis of LQTS-related genes. A novel missense mutation (L1825P) was identified within the C-terminus region of the cardiac Na
+
channel (
SCN5A
). The L1825P channel heterologously expressed in tsA-201 cells showed Na
+
current with slow decay and a prominent tetrodotoxin-sensitive noninactivating component, similar to the gain-of-function phenotype most commonly observed for
SCN5A
-associated congenital LQTS (LQT3). In addition, L1825P exhibited loss of function Na
+
channel features characteristic of Brugada syndrome. Peak Na
+
current density observed in cells expressing L1825P was significantly diminished, and the voltage dependence of activation and inactivation was shifted toward more positive and negative potentials, respectively.

Conclusions—

This study demonstrates that subclinical mutations in the LQTS-related gene
SCN5A
may predispose certain individuals to drug-induced cardiac arrhythmias.
Evidence for an Independent and Cumulative Effect of Postprandial Hypertriglyceridemia and Hyperglycemia on Endothelial Dysfunction and Oxidative Stress Generation
Authors: Ceriello Antonio , Taboga Claudio , Tonutti Laura , Quagliaro Lisa , Piconi Ludovica , Bais Bruno , Da Ros Roberto , Motz Enrico
Published: September 2002

Background—

Postprandial hypertriglyceridemia and hyperglycemia are considered risk factors for cardiovascular disease. Evidence suggests that postprandial hypertriglyceridemia and hyperglycemia induce endothelial dysfunction through oxidative stress; however, the distinct role of these two factors is a matter of debate.

Methods and Results—

Thirty type 2 diabetic patients and 20 normal subjects ate 3 different meals: a high-fat meal; 75 g glucose alone; and high-fat meal plus glucose. Glycemia, triglyceridemia, nitrotyrosine, and endothelial function were assayed during the tests. Subsequently, diabetics took 40 mg/d simvastatin or placebo for 12 weeks. The 3 tests were performed again at baseline, between 3 to 6 days after the start, and at the end of each study. High-fat load and glucose alone produced a decrease of endothelial function and an increase of nitrotyrosine in normal and diabetic subjects. These effects were more pronounced when high fat and glucose were combined. Short-term simvastatin treatment had no effect on lipid parameters but reduced the effect on endothelial function and nitrotyrosine observed during each different test. Long-term simvastatin treatment was accompanied by a lower increase in postprandial triglycerides, which was followed by smaller variations of endothelial function and nitrotyrosine during the tests.

Conclusions—

This study shows an independent and cumulative effect of postprandial hypertriglyceridemia and hyperglycemia on endothelial function, suggesting oxidative stress as common mediator of such effect. Simvastatin shows a beneficial effect on oxidative stress and endothelial dysfunction, which may be ascribed to a direct effect as well as the lipid-lowering action of the drug.
Calmodulin Kinase II and Arrhythmias in a Mouse Model of Cardiac Hypertrophy
Authors: Wu Yuejin , Temple Joel , Zhang Rong , Dzhura Igor , Zhang Wei , Trimble Robert , Roden Dan M. , Passier Robert , Olson Eric N. , Colbran Roger J. , Anderson Mark E.
Published: September 2002

Background—

Calmodulin kinase (CaMK) II is linked to arrhythmia mechanisms in cellular models where repolarization is prolonged. CaMKII upregulation and prolonged repolarization are general features of cardiomyopathy, but the role of CaMKII in arrhythmias in cardiomyopathy is unknown.

Methods and Results—

We studied a mouse model of cardiac hypertrophy attributable to transgenic (TG) overexpression of a constitutively active form of CaMKIV that also has increased endogenous CaMKII activity. ECG-telemetered TG mice had significantly more arrhythmias than wild-type (WT) littermate controls at baseline, and arrhythmias were additionally increased by isoproterenol. Arrhythmias were significantly suppressed by an inhibitory agent targeting endogenous CaMKII. TG mice had longer QT intervals and action potential durations than WT mice, and TG cardiomyocytes had frequent early afterdepolarizations (EADs), a hypothesized mechanism for triggering arrhythmias. EADs were absent in WT cells before and after isoproterenol, whereas EAD frequency was unaffected by isoproterenol in TG mice. L-type Ca
2+
channels (LTTCs) can activate EADs, and LTCC opening probability (Po) was significantly higher in TG than WT cardiomyocytes before and after isoproterenol. A CaMKII inhibitory peptide equalized TG and WT LTCC Po and eliminated EADs, whereas a peptide antagonist of the Na
+
/Ca
2+
exchanger current, also hypothesized to support EADs, was ineffective.

Conclusions—

These findings support the hypothesis that CaMKII is a proarrhythmic signaling molecule in cardiac hypertrophy in vivo. Cellular studies point to EADs as a triggering mechanism for arrhythmias but suggest that the increase in arrhythmias after β-adrenergic stimulation is independent of enhanced EAD frequency.
Stem Cell-Derived Cardiomyocytes Demonstrate Arrhythmic Potential
Authors: Zhang Ying Ming , Hartzell Criss , Narlow Michael , Dudley Samuel C.
Published: September 2002

Background—

Cardiomyocytes (CMs) derived from pluripotent embryonic stem cells (ESCs) and embryonal carcinoma cells (ECCs) have some but not all characteristics of adult myocytes. ESCs have shown the ability to engraft in areas of myocardial damage, which suggests their use in cell transplantation therapy for cardiomyopathy. We studied the arrhythmogenic properties of CMs differentiated from mouse ESCs and ECCs.

Methods and Results—

CMs derived in vitro were studied in the whole-cell patch-clamp mode. CMs from both sources showed action potential (AP) morphology heterogeneity, with reduced maximum upstroke velocities (dV/dt) and prolonged AP durations. CMs demonstrated prolonged, spontaneous electrical activity in culture. Frequent triggered activity was observed with and without pharmacological enhancement. Phase 2 or 3 early afterdepolarizations could be induced easily by Bay K8644 plus tetraethylammonium chloride (TEA) or [TEA]
o
after Cs
+
replacement for [K
+
]
i
, respectively. A combination of bradycardic stimulation, hypokalemia, and quinidine resulted in early afterdepolarizations. Delayed afterdepolarizations could be induced easily and reversibly by hypercalcemia or isoproterenol.

Conclusions—

ESCs or ECCs differentiated into at least 3 AP phenotypes. CMs showed spontaneous activity, low dV/dt, prolonged AP duration, and easily inducible triggered arrhythmias. These findings raise caution about the use of totipotent ESCs in cell transplantation therapy, because they may act as an unanticipated arrhythmogenic source from any of the 3 classic mechanisms (reentry, automaticity, or triggered activity).
Effect of Hyperhomocysteinemia on Plasma or Tissue Adenosine Levels and Renal Function
Authors: Chen Ya-Fei , Li Pin-Lan , Zou Ai-Ping
Published: September 2002

Background—

Hyperhomocysteinemia (hHcys) is considered an independent risk factor of cardiovascular diseases. Recent studies in our laboratory have shown that hHcys produced glomerular dysfunction and sclerosis independently of hypertension. However, the mechanism mediating these pathogenic effects of homocysteine (Hcys) is poorly understood. Because Hcys and adenosine (Ado) are simultaneously produced via hydrolysis of
S
-adenosylhomocysteine (SAH), we hypothesized that hHcys may produce its pathogenic effects by decrease in plasma or tissue Ado concentrations.

Methods and Results—

l
-Hcys (1.5 μmol/min per kilogram) was infused intravenously for 60 minutes to produce acute hHcys in Sprague-Dawley rats. Plasma Hcys levels increased from 6.7±0.4 to 14.7±0.5 μmol/L, but Ado decreased from 141.7±15.1 to 52.4±6.8 nmol/L in these rats with acute hHcys. This hHcys-induced reduction of Ado was also observed in the kidney dialysate. In rats with chronic hHcys, plasma Ado levels were also significantly decreased. By kinetic analysis of the enzyme activities, decrease in renal Ado levels in hHcys was shown to be associated with inhibition of SAH hydrolase but not 5′-nucleotidase. Functionally, intravenous infusion of Hcys was found to decrease renal blood flow, glomerular filtration rate, and sodium and water excretion, which could be blocked by the Ado receptor antagonist 8-SPT.

Conclusions—

These results strongly suggest that hHcys decreases plasma and tissue Ado concentrations associated with inhibition of SAH hydrolase. Decrease in plasma and tissue Ado may be an important mechanism mediating the pathogenic effects of Hcys.
Effect of Low-Dose Aspirin on Vascular Inflammation, Plaque Stability, and Atherogenesis in Low-Density Lipoprotein Receptor–Deficient Mice
Authors: Cyrus Tillmann , Sung Syuan , Zhao Lei , Funk Colin D. , Tang Syun , Praticò Domenico
Published: September 2002

Background—

Atherosclerosis is a complex vascular inflammatory disease. Low-dose aspirin is a mainstay in the prevention of vascular complications of atherosclerosis. We wished to determine the effect of low-dose aspirin on vascular inflammation, plaque composition, and atherogenesis in LDL receptor–deficient mice fed a high fat diet.

Methods and Results—

In LDL receptor–deficient mice fed a high fat diet compared with control mice, low-dose aspirin induced a significant decrease in circulating levels and vascular formation of soluble intercellular molecule-1, monocyte chemoattractant protein-1, tumor necrosis factor-α, interleukin-12p 40, without affecting lipid levels. This was associated with significant reduction of the nuclear factor κB activity in the aorta. Low-dose aspirin also significantly reduced the extent of atherosclerosis. Finally, aortic vascular lesions of the aspirin-treated animals showed 57% reduction (
P
<0.05) in the amount of macrophage cells, 77% increase in smooth muscle cells (
P
<0.05), and 23% increase in collagen (
P
<0.05).

Conclusions—

Our results suggest that in murine atherosclerosis, low-dose aspirin suppresses vascular inflammation and increases the stability of atherosclerotic plaques, both of which, together with its antiplatelet activity, contribute to its antiatherogenic effect. We conclude that low-dose aspirin might be rationally evaluated in the progression and evolution of human atherosclerotic plaque.
Effect of Treatment for
Chlamydia pneumoniae
and
Helicobacter pylori
on Markers of Inflammation and Cardiac Events in Patients With Acute Coronary Syndromes
Authors: Stone Adam F.M. , Mendall Michael A. , Kaski Juan-Carlos , Edger Tracey M. , Risley Paul , Poloniecki Jan , Camm A. John , Northfield Timothy C.
Published: September 2002

Background—

Infection with
Helicobacter pylori
and
Chlamydia pneumoniae
is associated with coronary heart disease. We conducted an intervention study using antibiotics against these bacteria in patients with acute coronary syndromes to determine whether antibiotics reduce inflammatory markers and adverse cardiac events.

Methods and Results—

Patients (n=325) admitted with acute myocardial infarction or unstable angina (acute coronary syndromes) were randomized to receive a 1-week course of 1 of 3 treatment regimens: (1) placebo; (2) amoxicillin (500 mg twice daily), metronidazole (400 mg twice daily), and omeprazole (20 mg twice daily); or (3) azithromycin (500 mg once daily), metronidazole (400 mg twice daily), and omeprazole (20 mg twice daily). Serum fibrinogen, white cell count, and high-sensitivity C-reactive protein were measured at study entry and at 1, 3, and 12 months during follow-up. Cardiac death and readmission with acute coronary syndrome were considered clinical end points. Patients were followed for 1 year. C-reactive protein levels were reduced (
P
=0.03) in unstable angina patients receiving amoxicillin, and fibrinogen was reduced in both patient groups receiving antibiotics (
P
=0.06). There were 17 cardiac deaths and 71 readmissions with acute coronary syndrome. No difference in frequency or timing of end points was observed between the 2 antibiotic groups. At 12 weeks, there was a 36% reduction in all end points in patients receiving antibiotics compared with placebo (
P
=0.02). This reduction persisted during the 1-year follow-up. Neither
C pneumoniae
nor
H pylori
antibody status was significantly related to response to treatment.

Conclusions—

Antibiotic treatment significantly reduced adverse cardiac events in patients with acute coronary syndromes, but the effect was independent of
H pylori
or
C pneumoniae
seropositivity.
Segmental Ostial Ablation to Isolate the Pulmonary Veins During Atrial Fibrillation
Authors: Oral Hakan , Knight Bradley P. , Özaydın Mehmet , Chugh Aman , Lai Steve W.K. , Scharf Christoph , Hassan Sohail , Greenstein Radmira , Han Jihn D. , Pelosi Frank , Strickberger S. Adam , Morady Fred
Published: September 2002

Background—

The purpose of this study was to determine the feasibility and mechanistic implications of segmental pulmonary vein (PV) ostial ablation during atrial fibrillation (AF).

Methods and Results—

Forty consecutive patients underwent PV isolation for AF. Among 125 PVs targeted for isolation, ablation was performed during AF in 70 veins and during sinus rhythm in 55 veins. A decapolar Lasso catheter was positioned near the ostium. During AF, ostial ablation was performed near the Lasso catheter electrodes that recorded a tachycardia with a cycle length shorter than in the adjacent left atrium. During sinus rhythm, ostial ablation was guided by PV potentials. Complete PV isolation was achieved in 70 PVs (100%) ablated during AF and in 53 PVs (96%) ablated during sinus rhythm (
P
=0.4). The mean durations of radiofrequency energy needed for isolation were 7.4±4.4 and 5.2±3.9 minutes during AF and sinus rhythm, respectively (
P
<0.01). Before ablation, an immediate recurrence of AF (IRAF), occurred after cardioversion in 18 of 40 patients, and IRAF was consistently abolished by PV isolation. The probability of AF termination during isolation of a PV was directly related to the extent of tachycardia in that vein. As more PVs were isolated, induction of persistent AF by rapid pacing became less likely.

Conclusions—

Segmental ostial ablation guided by PV tachycardia during AF is feasible and as efficacious as during sinus rhythm. The responses to cardioversion, ablation, and rapid pacing observed in this study imply that IRAF is triggered by the PVs and that PV tachycardias may play an important role in the perpetuation of AF.
Death Following Creatine Kinase-MB Elevation After Coronary Intervention
Authors: Ellis Stephen G. , Chew Derek , Chan Albert , Whitlow Patrick L. , Schneider Jakob P. , Topol Eric J.
Published: September 2002

Background—

Creatine kinase (CK)-MB elevation after percutaneous coronary intervention (PCI) has been associated with subsequent cardiac death. The patients at risk, the timing of risk, and potential treatment implications are uncertain.

Methods and Results—

Eight thousand, four hundred nine consecutive non– acute myocardial infarction patients with successful PCI and no emergency surgery or Q-wave myocardial infarction were followed for 38±25 months; 1446 (17.2%) had post-PCI CK-MB above normal on routine ascertainment. Patients were prospectively stratified into those with CK-MB 1 to 5× or CK-MB >5× normal. No patient with CK-MB 1 to 5× normal died during the first week after PCI, and excess risk of early death for patients with CK-MB elevation occurred primarily in the first 3 to 4 months. The actuarial 4-month risk of death was 8.9%, 1.9%, and 1.2% for patients with CK-MB >5×, CK-MB 1 to 5×, and CK-MB ≤1× normal (
P
<0.001). Death within 4 months was independently correlated with the degree of CK-MB elevation, creatinine ≥2 mg%, post-PCI C-reactive protein, low ejection fraction, age, and congestive heart failure class (
P
<0.01 for all). In a matched subset analysis, incomplete revascularization (
P
<0.001), congestive heart failure class (
P
=0.005), and no statin treatment at hospital discharge (
P
=0.009) were associated with death.

Conclusions—

Patients with CK-MB elevation after PCI are at excess risk of death for 3 to 4 months, although prolonging hospitalization for CK-MB 1 to 5× is unlikely to modify risk. CK-MB >5× normal, incomplete revascularization, elevated C-reactive protein, heart failure, the elderly, and hospital discharge without on statin therapy increases risk. Several of these factors suggest that inflammation may play a part in the excess risk of death.