bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fracture toughening of epoxy matrices with blends of resins of different molecular weights and other modifiers
Authors: Zubeldia A. , Larrañaga M. , Remiro P. , Mondragon I. 
Published: September 2004

AbstractThe microstructure and fracture behavior of epoxy mixtures containing two monomers of different molecular weights were studied. The variation of the fracture toughness by the addition of other modifiers was also investigated. Several amounts of high‐molecular‐weight diglycidyl ether of bisphenol A (DGEBA) oligomer were added to a nearly pure DGEBA monomer. The mixtures were cured with an aromatic amine, showing phase separation after curing. The curing behavior of the epoxy mixtures was investigated with thermal measurements. A significant enhancement of the fracture toughness was accompanied by slight increases in both the rigidity and strength of the mixtures that corresponded to the content of the high‐molecular‐weight epoxy resin. Dynamic mechanical and atomic force microscopy measurements indicated that the generated two‐phase morphology was a function of the content of the epoxy resin added. The influence of the addition of an oligomer or a thermoplastic on the morphologies and mechanical properties of both epoxy‐containing mixtures was also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3920–3933, 2004
Interfacial effects in organophilic montmorillonite–poly(ϵ‐caprolactone) nanocomposites
Authors: Pucciariello Rachele , Villani Vincenzo , Langerame Fausto , Gorrasi Giuliana , Vittoria Vittoria 
Published: September 2004

AbstractIn the last few years much progress has been made in the development of hybrid polymer–inorganic filler nanocomposites. Nevertheless, many questions remain. The comprehension of the structure and the interactions at the polymer–nanofiller interface are crucial to foresee and control the properties of nanocomposites. Because of the high surface ratio of the inorganic nanofiller, the interface is expected to have a prevailing role in determining the nanocomposite properties. In this study we use X‐ray photoelectron spectroscopy (XPS) as a tool for the surface characterization of an organophilic montmorillonite/poly(ε‐caprolactone) exfoliated nanocomposite. The XPS core levels of the nanocomposite have been compared with those obtained from its precursors, and analyzed as reference compounds to evaluate eventual differences attributable to the polymer–nanofiller interfacial interactions. The XPS investigation has allowed us to propose a qualitative model of possible interface interactions between poly(ε‐caprolactone) and the organo‐modified montmorillonite. The model is substantiated by Fourier transform infrared spectroscopy (FTIR). © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3907–3919, 2004
Hylleraas method for many‐electron atoms. I. The Hamiltonian
Authors: Ruiz María Belén 
Published: September 2004

AbstractA general expression for the nonrelativistic Hamiltonian for n‐electron atoms with the fixed nucleus approximation is derived in a straightforward manner using the chain rule. The kinetic energy part is transformed into the mutually independent distance coordinates ri, rij, and the polar angles θi, and φi. This form of the Hamiltonian is very appropriate for calculating integrals using Slater orbitals, not only of states of S symmetry, but also of states with higher angular momentum, as P states. As a first step in a study of the Hylleraas method for five‐electron systems, variational calculations on the 2P ground state of boron atom are performed without any interelectronic distance. The orbital exponents are optimized. The single‐term reference wave function leads to an energy of −24.498369 atomic units (a.u.) with a virial factor of η = 2.0000000009, which coincides with the Hartree–Fock energy −24.498369 a.u. A 150‐term wave function expansion leads to an energy of −24.541246 a.u., with a factor of η = 1.9999999912, which represents 28% of the correlation energy. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Hylleraas method for many‐electron atoms. II. Integrals over wave functions with one interelectronic coordinate
Authors: Belén Ruiz María 
Published: September 2004

AbstractA procedure is proposed to evaluate matrix elements containing r linked with angular functions. Using this procedure, the different types of two‐, three‐, and four‐electron radial and angular integrals that appear in a five‐electron atom, in the case of only one rij coordinate per basis function, are written in a compact form, separated in radial coordinates of one electron. The general formulas with which to obtain the integrals for powers ν ≥ 1 are developed, based on the orthogonality of the Legendre polynomials. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Application of algebraic method to the high overtones of C6H6 and C6D6
Authors: Lu Daoming , Lu Liping , Ping Jialun 
Published: September 2004

AbstractBoth the spectra and infrared transition strengths of C6H6 and C6D6 for the CH stretching overtones up to as high as v = 10 are described in high precision with few parameters (six for the spectra and four for the transition strengths) by the Iachello–Oss algebraic model. The Hamiltonian model is solved in the symmetry adapted bases, which are constructed by the symmetrized boson representation (SBR) technique. The results show that the combination of the algebraic method and SBR technique is a powerful method for describing vibrations of large molecules and high overtones. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Influence of the electric field on a particle in a space with a disclination
Authors: Azevedo Sérgio 
Published: September 2004

AbstractWe consider a quantum particle in a space with a linear topological defect, i.e., disclination. The effect of the uniform electric field in this space, on the particle, is shown to cause a translation of the wave function. In addition, the electric field is not found to be affected by the defect. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Construction of characteristic polynomial of reciprocal graphs from the number of pendant vertices
Authors: Mandal Bholanath , Banerjee Manas , Mukherjee Asok K. 
Published: September 2004

AbstractA method for construction of the characteristic polynomial (CP) coefficients of the three classes of reciprocal graphs, viz., Ln + n(p), Cn + n(p), and K1,n−1 + n(p), has been developed that requires only the value of n. The working formulas have been expressed in matrix product form, computer programs for which can easily be developed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Structure and stability of B8 clusters
Authors: Li Qianshu , Zhao Yi , Xu Wenguo , Li Nan 
Published: September 2004

AbstractWe investigated various isomers of B8 clusters with ab initio (MP2) and density function theory (DFT) methods (B3LYP and B3PW91). Nineteen B8 isomers were determined to be local minima on their potential energy hypersurfaces by the B3LYP, B3PW91, and MP2 methods. Fifteen of these structures are first reported. The most stable neutral B8 cluster is the regular heptagon, with another boron atom at the center (D7h, triplet), in agreement with results reported previously. The natural bond orbital (NBO) analysis and nucleus‐independent chemical shifts (NICS) further reveal that the most stable species have delocalized π bond and multicentered σ bonds and therefore exhibit multiple‐fold aromaticity. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Computer simulations of voltage‐gated potassium channel KvAP
Authors: Tieleman D. Peter , Robertson Kindal M. , Maccallum Justin L. , Monticelli Luca 
Published: September 2004

AbstractThe recent crystal structures of the voltage‐gated potassium channel KvAP and its isolated voltage‐sensing “paddle” (composed of segments S1 to S4) (Jiang et al., Nature 2003, 423, 33–41) challenged existing models of voltage gating and encouraged a large number of experimental and theoretical studies to answer a number of questions about the structure of the physiologically relevant states of voltage‐gated potassium channels and their gating mechanism. We describe equilibrium simulations of the KvAP crystal structure. The crystal structure of the full channel undergoes a large conformational change, localized to the S1–S4 domains, as the S1–S4 domains move into the membrane. We also present a model of the closed state, in agreement with the position of the paddle in the paddle model of voltage gating. Finally, we estimate the energetic cost of transferring a single arginine sidechain from water into an octane slab with the approximate hydrophobic thickness of a membrane. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Atmospheric pressure chemical ionization mass spectrometry of aldehydes in biological matrices
Authors: Nagy Kornél , Pollreisz Ferenc , Takáts Zoltán , Vékey Károly 
Published: September 2004

AbstractApplication of high‐performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) for detection of aldehydes in biological samples such as blood, yoghurt, and milk, is reported. Sample preparation is easy, and the presented method is both sensitive and selective. It is based on the widely used dinitrophenylhydrazine derivatization, followed by extraction with n‐hexane and a simple reversed‐phase HPLC separation. Detection is performed by atmospheric pressure chemical ionization (APCI) in negative ion mode, with detection limits in the low picogram range. Using MS/MS, acetone and propionaldehyde can clearly be distinguished, facilitating propionaldehyde quantitation even in the presence of high acetone levels. Quantitation by direct MS/MS is also feasible, well suited for high‐throughput applications, although not as accurate as using HPLC/MS/MS. Copyright © 2004 John Wiley & Sons, Ltd.
High‐resolution analysis by nano‐electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry for the identification of molecular species of phospholipids and their oxidized metabolites
Authors: Ishida Mayuko , Yamazaki Toshiyuki , Houjou Toshiaki , Imagawa Masayoshi , Harada Ayako , Inoue Keizou , Taguchi Ryo 
Published: September 2004

AbstractNano‐electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) was applied to identify the molecular species of phosphatidylethanolamine of Caenorhabditis elegans, which has a high concentration of phospholipids with a fatty acyl chain having an odd number of carbon atoms. The molecular species of diacyl phosphatidylethanolamine with one fatty acyl chain having an odd number of carbon atoms and one fatty acyl chain having an even number of carbon atoms was identified separately from alkyl‐acyl phosphatidylethanolamine with an alkyl chain having an even number of carbon atoms and a fatty acyl chain having an even number of carbon atoms. Furthermore, nano‐ESI‐FTICRMS was applied to the direct identification of oxidized phosphatidylcholine from soybean. The mass peaks of individual molecular species of oxidative phosphatidylcholine, such as 34:3 diacyl phosphatidylcholine with peroxide (+2O) (m/z 788.544) or 34:2 diacyl phosphatidylcholine with peroxide (+2O) (m/z 790.560), can be separated from the peaks of the molecular species of the non‐oxidative phospholipids. This suggests that the mass peaks with a difference of less than 0.1 mass units in their molecular weight can be separated and that their individual exact molecular compositions can be obtained by the FTICRMS analysis. The high resolution and high accuracy of FTICRMS are very effective in the analysis of molecular species of phospholipids and their derivatives. Copyright © 2004 John Wiley & Sons, Ltd.
Microbial responses to in situ chemical oxidation, six‐phase heating, and steam injection remediation technologies in groundwater
Authors: Azadpour‐Keeley Ann , Wood Lynn A. , Lee Tony R. , Mravik Susan C. 
Published: September 2004

AbstractThe evaluation of microbial responses to three in situ source removal remedial technologies—permanganate‐based in situ chemical oxidation (ISCO), six‐phase heating (SPH), and steam injection (SI)—was performed at Cape Canaveral Air Station in Florida. The investigation stemmed from concerns that treatment processes could have a variety of effects on the indigenous biological activity, including reduced biodegradation rates and a long‐term disruption of community structure with respect to the stimulation of TCE (trichloroethylene) degraders. The investigation focused on the quantity of phospholipid fatty acids (PLFAs) and its distribution to determine the immediate effect of each remedial technology on microbial abundance and community structure, and to establish how rapidly the microbial communities recovered. Comprehensive spatial and temporal PLFA screening data suggested that the technology applications did not significantly alter the site's microbial community structure. The ISCO was the only technology found to stimulate microbial abundance; however, the biomass returned to predemonstration values shortly after treatment ended. In general, no significant change in the microbial community composition was observed in the SPH or SI treatment areas, and even small changes returned to near initial conditions after the demonstrations. © 2004 Wiley Periodicals, Inc.
Characterization and pilot‐scale studies for chemical oxidation remediation of fractured shale
Authors: Goldstein Kenneth J. , Vitolins Andrew R. , Navon Daria , Parker Beth L. , Chapman Steven , Anderson Grant A. 
Published: September 2004

AbstractThe distribution of volatile organic compounds (VOCs) in fractured shale overlain by thin (< 10 feet) overburden at the Watervliet Arsenal near Albany, New York, was initially determined by sampling water from the fracture network using packer systems in boreholes and also using conventional monitoring wells. Furthermore, short‐term pumping and injection tests were conducted and the boreholes were logged using a variety of geophysical and hydrophysical tools. Tetrachloroethene is the dominant VOC in the groundwater, with lesser concentrations of trichloroethene and degradation products (cis‐1,2‐dichloroethene, trans‐1,2‐dichloroethene, and vinyl chloride). The vertical VOC distributions in the rock matrix were obtained from continuous‐cored holes from which small rock samples, collected at many depths between 18 and 150 feet below ground surface, were analyzed. The rock core VOC concentrations were determined by methanol extraction of crushed rock followed by direct methanol injection onto a gas chromatograph and subsequent estimation of rock porewater VOC concentrations. The rock core data support the concept that diffusion‐driven mass transfer has caused nearly all the VOC mass initially present in the fractures to now reside in the rock matrix, which has a porosity three or four orders of magnitude larger than the bulk fracture porosity. The results of the site characterization indicate that an effective site investigation strategy in fractured shale must include characterization of both the fracture and matrix contaminant distribution. These results also indicate that the most favorable remediation technologies for this fractured shale are those that will destroy VOCs in the rock matrix, particularly contaminants in the sorbed phase, and also destroy the VOC mass in the fractures including both dissolved and immiscible phases. The site characterization resulted in the selection of potassium permanganate for an in situ chemical oxidation pilot study. © 2004 Wiley Periodicals, Inc.
The maturing of the Triad approach: Avoiding misconceptions
Authors: Crumbling Deana M. , Hayworth Joel S. , Call Bradley A. , Davis William M. , Howe Robert , Miller David S. , Johnson Robert 
Published: September 2004

AbstractMisunderstandings and misconceptions have arisen as the Triad approach has gained wider application. The Triad initiative's ability to catalyze second‐generation cleanup practices will be hampered if inaccurate or incomplete assumptions create persistent confusion about what Triad is or how it works. This article has been prepared by the multi‐agency workgroup responsible for articulating the Triad approach and coordinating national Triad efforts. It serves to address some misunderstandings about key Triad concepts. As an aid to those wishing to learn more, a new Web site (the Triad Resource Center, http://www.triadcentral.org) and a new Triad reference document from the Interstate Technology and Regulatory Council (ITRC) are introduced as sources of explanatory information supporting the Triad approach. © 2004 Wiley Periodicals, Inc.
Integrating critical thinking and systems thinking: from premises to causal loops
Authors: Cavana Robert Y. , Mares Edwin D. 
Published: September 2004

AbstractThis article demonstrates how to construct a policy argument from the perspective of critical thinking and how to convert this into a causal loop diagram utilising the tools of systems thinking and system dynamics. It is based on the authors' recent work on the Demonstrating Values project with the New Zealand Customs Service, which involved integrating critical thinking and systems thinking into the policy development process. Critical thinking is used in this context to reconstruct a rationale for a given policy. This helped us to isolate key concepts and desired outcomes. The concepts were then used to construct a conceptual diagram. Based on this, the key concepts were operationalised to form a causal loop diagram including the main variables of interest in the system. The causal loop diagram can then be used as the basis for further policy interventions and analysis. Copyright © 2004 John Wiley & Sons, Ltd.
Models for collaboration: how system dynamics helped a community organize cost‐effective care for chronic illness
Authors: Homer Jack , Hirsch Gary , Minniti Mary , Pierson Marc 
Published: September 2004

AbstractChronic illness is a large and growing problem throughout the world. Experts agree that the U.S. health care system is poorly organized to care for chronic illnesses and, as a result, is wasteful and unresponsive to the needs of patients. This article describes a program to improve chronic care in a county of Washington State, and how system dynamics models focusing on diabetes and heart failure supported the planning of that program. The models project the program's costs and beneﬁts over 20 years and have given its leadership the ability to do resource planning, set realistic expectations, determine critical success factors, and evaluate the differential impacts on affected parties. Relying upon model projections, the leadership is seeking ways to address concerns about ﬁnancial “winners” and “losers” so that all parties are willing to participate in and support the program. Copyright © 2004 John Wiley & Sons, Ltd.
Tool support for geographically dispersed inspection teams
Authors: Lanubile Filippo , Mallardo Teresa , Calefato Fabio 
Published: September 2004

AbstractSoftware inspection is one of software engineering's best practices for detecting and removing defects early in the development process. However, the prevalence of manual activities and face‐to‐face meetings within software inspections hinder their applicability in the context of global software development, where software engineering activities are spread across multiple sites and even multiple countries.In this article, we describe a web‐based tool, called the Internet‐Based Inspection System (IBIS), that aims to support geographically dispersed inspection teams. On the basis of findings from empirical studies of software inspections, the IBIS tool adopts a reengineered inspection process to minimize synchronous activities and coordination problems. We present the underlying process model, how the tool is used within the inspection stages, and experiences using the IBIS tool as the enabling infrastructure for distributed software inspections. Copyright © 2004 John Wiley & Sons, Ltd.
Architecture as a coordination tool in multi‐site software development
Authors: Ovaska Päivi , Rossi Matti , Marttiin Pentti 
Published: September 2004

AbstractA widely held understanding of coordination in software development is that it focuses on coordinating development activities to achieve a common goal. Our study, a case study in an international ICT company, suggests that in multi‐site environment, it is not enough to coordinate development activities to achieve a common goal. Rather, more emphasis should be put on coordinating interdependencies between activities. Shifting the interest from activities (and subsystems) toward system‐level dependencies requires software architects and developers to have a common understanding of the software architecture. Our findings reflect coordination challenges in multi‐site environment with geographically dispersed teams. On the basis of the findings, we claim that architecture could be used to coordinate distributed development. However, this requires that the chief architect is capable of maintaining the integrity of the architecture and of communicating it. Furthermore, we list some requirements for a development methodology that uses architecture to support the coordination. Copyright © 2004 John Wiley & Sons, Ltd.
Global software development in practice lessons learned
Authors: Prikladnicki Rafael , Nicolas Audy Jorge Luis , Evaristo Roberto 
Published: September 2004

AbstractMore than a decade ago, organizations seeking lower costs and access to skilled resources began to experiment with remotely located software development facilities. This change is having a profound impact not only on marketing and distribution but also on the way products are conceived, designed, constructed, tested, and delivered to customers. The number of organizations distributing their software development processes worldwide keeps increasing. As a result, software development is becoming a multi‐site, multicultural and globally distributed undertaking. More recently, attention has turned toward trying to understand the factors that enable multinationals and virtual corporations to operate successfully across geographic and cultural boundaries. On the basis of these factors, we present the lessons learned from case studies in two software development units from multinational organizations located in Brazil. Copyright © 2004 John Wiley & Sons, Ltd.
Positive solutions to superlinear second-order divergence type elliptic equations in cone-like domains
Authors: Kondratiev Vladimir , Liskevich Vitali , Moroz Vitaly 
Published: September 2004

We study the problem of the existence and nonexistence of positive solutions to the superlinear second-order divergence type elliptic equation with measurable coefficients

−\mathrm{∇} \cdot a \cdot \mathrm{∇}u = u^{p}

(*),\ p > 1

, in an unbounded cone-like domain

G \subset \mathbb{R}^{N}

(N⩾3)

. We prove that the critical exponent

p^{*}(a\text{,}G) = \mathrm{\inf }\{p > 1:\:(*)\:\text{has a positive supersolution at infinity in}\:G\}

for a nontrivial cone-like domain is always in

(1\text{,}\frac{N}{N−2})

and depends both on the geometry of the domain
G
and the coefficients
a
of the equation.

Résumé

Nous étudions le problème d'existence ou non existence de solutions positives d'équations elliptiques de type divergence du second-ordre superlinéaires à coefficients mesurables

−\mathrm{∇} \cdot a \cdot \mathrm{∇}u = u^{p}

(*)

,

p > 1

, sur un domaine conique

G \subset \mathbb{R}^{N}

(N⩾3)

. Nous prouvons que l'exposant critique

p^{*}(a\text{,}G) = \mathrm{\inf }\{p > 1:\:(*)\:\text{a une supersolution positive à l'infini dans}\:G\}

pour un domaine conique non–trivial est toujours dans

(1\text{,}\frac{N}{N−2})

, dépend à la fois de la géometrie du domaine
G
et des coefficients
a
de l'équation.