bluuebunny/crossref_metadata_2025 huggingface dataset:
Hyperbranched aryl polycarbonates derived from A2B monomers versus AB2 monomers
Authors: Bolton Daniel H. , Wooley Karen L.
Published: October 2004

Hyperbranched aryl polycarbonates were prepared via the polymerizations of A2B and AB2 monomers, which involved the condensation of chloroformate (A) functionalities with tert‐butyldimethylsilyl‐protected phenols (B), facilitated by reactions with silver fluoride. The polymerization of the A2B monomer gave hyperbranched polycarbonates bearing fluoroformate chain ends, which were hydrolyzed to phenolic chain‐end moieties and further elaborated to tert‐butyldimethylsilyl ether groups. The polymerization of the AB2 monomer gave tert‐butyldimethylsilyl ether‐terminated hyperbranched polycarbonates. The polymerizations were conducted at 23–70 °C in 20% acetonitrile/tetrahydrofuran in the presence of a stoichiometric excess of silver fluoride for 20–40 h to afford hyperbranched polycarbonates with weight‐average molecular weights exceeding 100,000 Da and polydispersity indices of typically 2–3. The degrees of branching were determined by a reductive degradation procedure followed by high‐performance liquid chromatography. Alternatively, the degrees of branching were measurable by solution‐state 1H NMR analyses and agreed with the statistical 50% branching expected for the polymerization of A2B and AB2 monomers not experiencing constructive or destructive electronic effects on the reactivity of the multiple functional groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 823–835, 2002; DOI 10.1002/pola.10167
Poly(ethylene terephthalate) reinforced by N,N′‐diphenyl biphenyl‐3,3′,4,4′‐tetracarboxydiimide moieties
Authors: Xiao Jun , Wan Xinhua , Zhang Dong , Zhang Hailiang , Zhou Qi‐Feng , Turner S. Richard
Published: October 2004

Starting with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and methyl aminobenzoate, we synthesized a novel rodlike imide‐containing monomer, N,N′‐bis[p‐(methoxy carbonyl) phenyl]‐biphenyl‐3,3′,4,4′‐tetracarboxydiimide (BMBI). The polycondensation of BMBI with dimethyl terephthalate and ethylene glycol yielded a series of copoly(ester imide)s based on the BMBI‐modified poly(ethylene terephthalate) (PET) backbone. Compared with PET, these BMBI‐modified polyesters had higher glass‐transition temperatures and higher stiffness and strength. In particular, the poly(ethylene terephthalate imide) PETI‐5, which contained 5 mol % of the imide moieties, had a glass‐transition temperature of 89.9 °C (11 °C higher than the glass‐transition temperature of PET), a tensile modulus of 869.4 MPa (20.2 % higher than that of PET), and a tensile strength of 80.8 MPa (38.8 % higher than that of PET). Therefore, a significant reinforcing effect was observed in these imide‐modified polyesters, and a new approach to higher property polyesters was suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 852–863, 2002; DOI 10.1002/pola.10169
Direct current conductivity and ion motions in poly(vinyl chloride)‐poly‐1,4‐cis butadiene blends by electrical relaxation method
Authors: Anada Yuichi
Published: October 2004

Ionic conduction in poly(vinyl chloride) (PVC)‐poly‐1,4‐cis butadiene blends has been studied using the electrical relaxation method. Temperature dependence of direct current (dc) conductivity does not change at the glass transition of PVC but does change at higher temperatures. The shape of the frequency dispersion curve of the electric modulus in a frequency range from 0.01 to 100 Hz depends on temperature. At low temperatures, the shape of the dispersion curve is reproduced by calculation assuming the Debye decay function, whereas this is not reproduced at high temperatures. Two kinds of analysis of the dispersion curve are discussed for this complicated change in the shape of the dispersion. One is that the dispersion curve is regarded as a single process expressed by the Kohlrausch decay function, and the other is that the curve is regarded as two processes expressed by the Debye and the Kohlrausch decay functions. The observed dispersion of the electric modulus is not expressed by the single process but by the two processes. One of the two processes is characterized by the Debye decay function, and the other is characterized by the Kohlrausch decay function. The parameter of the Kohlrausch decay function for one of these processes has a value of 0.82, and this value does not depend on temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 226–235, 2002
Surface modification on thermoplastic olefins by low‐temperature cascade arc discharge‐air plasmas for enhanced adhesion with primer
Authors: Lin Yung‐Sen , Yasuda Hirotsugu K.
Published: October 2004

Improvement of primer adhesion to thermoplastic olefins (TPOs) by surface modification with a low‐temperature cascade arc discharge‐air plasmas was investigated. Air plasma with a low‐temperature cascade arc plasma torch can be used for improving the primer adhesion to TPOs. Tape‐adhesion tests (ASTM 3359‐92a method) demonstrated this improvement with a rating of “0” for untreated TPOs and “5” for air plasma‐modified TPOs at certain plasma conditions even for aging at 60 °C and 80% relative humidity for 5 days. The adhesion to primer for the soft and flexible kind of TPOs (ETA‐3041c and ETA‐3101) was easily enhanced. The adhesion to primer for the hard and brittle TPOs (ETA‐3183) needs to optimize the plasma conditions to pass the wet‐adhesion test using air plasmas. To relate the surface characteristics of air plasma‐modified TPOs to adhesion performance with primer, the wettability and polarity of TPOs were evaluated by the contact‐angle measurements of primer and deionized water to TPOs. TPO surface morphology was evaluated using scanning electron microscopy. The surface composition was characterized with electron spectroscopy for chemical analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 623–637, 2002; DOI 10.1002/polb.10122
Laryngeal hirudiniasis: An unusual cause of airway obstruction and hemoptysis
Authors: Mohammad Yousser , Rostum M. , Dubaybo Basim A.
Published: October 2004

Cases of childhood hemoptysis are rare and usually result from foreign body aspiration or congenital heart or lung diseases. However, human hirudiniasis due to the leech still exists, and could involve the upper airways after drinking infested water from quiet streams and pools.

We report the case of a 6‐year‐old child who presented suffocating at the emergency room after having been misdiagnosed and treated for asthma over a 1‐month period. His mother reported he had had recurrent hemoptysis, as well. The child inadvertently drank leech‐infested water in a rural area of northern Syria. Surgical removal of the leech resulted in prompt resolution of the symptoms.

Although laryngeal hirudiniasis is rare in the developed world, it remains a possible cause of childhood airway obstruction, hemoptysis, and anemia which needs to be considered in patients with a suggestive history. Pediatr Pulmonol. 2002; 33:224–226. © 2002 Wiley‐Liss, Inc.
Geometric and chemical patterns of interaction in protein–ligand complexes and their application in docking
Authors: Moreno Ernesto , León Kalet
Published: October 2004

We present a new method for representing the binding site of a protein receptor that allows the use of the DOCK approach to screen large ensembles of receptor conformations for ligand binding. The site points are constructed from templates of what we called “attached points” (ATPTS). Each template (one for each type of amino acid) is composed of a set of representative points that are attached to side‐chain and backbone atoms through internal coordinates, carry chemical information about their parent atoms and are intended to cover positions that might be occupied by ligand atoms when complexed to the protein. This method is completely automatic and proved to be extremely fast. With the aim of obtaining an experimental basis for this approach, the Protein Data Bank was searched for proteins in complex with small molecules, to study the geometry of the interactions between the different types of protein residues and the different types of ligand atoms. As a result, well‐defined patterns of interaction were obtained for most amino acids. These patterns were then used for constructing a set of templates of attached points, which constitute the core of the ATPTS approach. The quality of the ATPTS representation was demonstrated by using this method, in combination with the DOCK matching and orientation algorithms, to generate correct ligand orientations for >1000 protein–ligand complexes. Proteins 2002;47:1–13. © 2002 Wiley‐Liss, Inc.
Noncovalent interaction energies in covalent complexes: TEM‐1 β‐lactamase and β‐lactams
Authors: Wang Xiaojun , Minasov George , Shoichet Brian K.
Published: October 2004

The class A β‐lactamase TEM‐1 is a key bacterial resistance enzyme against β‐lactam antibiotics, but little is known about the energetic bases for complementarity between TEM‐1 and its inhibitors. Most inhibitors form a covalent adduct with the catalytic Ser70, making the measurement of equilibrium constants, and hence interaction energies, technically difficult. This study evaluates noncovalent interactions within covalent complexes by examining the differential stability of TEM‐1 and its inhibitor adducts. The thermal denaturation of TEM‐1 follows a two‐state, reversible model with a melting temperature (Tm) of 51.6°C and a van't Hoff enthalpy of unfolding (ΔHVH) of 146.2 kcal/mol at pH 7.0. The stability of the enzyme changes on forming an inhibitor adduct. As expected, some inhibitors stabilize TEM‐1; transition‐state analogues increase the Tm by up to 3.7°C (1.7 kcal/mol). Surprisingly, all β‐lactam covalent acyl–enzyme complexes tested destabilize TEM‐1 significantly relative to the apo‐enzyme. For instance, the clinically used inhibitor clavulanic acid and the β‐lactamase‐resistant β‐lactams moxalactam and imipenem destabilize TEM‐1 by over 2.6°C (1.2 kcal/mol) in their covalent adducts. Based on the structure of the TEM‐1/imipenem complex (Maveyraud et al., J Am Chem Soc 1998;120:9748–52), destabilization by moxalactam and imipenem is thought to be caused by a steric clash between the side‐chain of Asn132 and the 6(7)‐α group of these β‐lactams. To test this hypothesis, the mutant enzyme N132A was made. In contrast with wild‐type, the covalent complexes between N132A and both imipenem and moxalactam stabilize the enzyme, consistent with the hypothesis. To investigate the structural bases of this dramatic change in stability, the structure of N132A/imipenem was determined by X‐ray crystallography. In the complex with N132A, imipenem adopts a very different conformation from that observed in the wild‐type complex, and the putative destabilizing interaction with residue 132 is relieved. Studies of several enzymes suggest that β‐lactams, and covalent inhibitors in general, can have either net favorable or net unfavorable noncovalent interaction energies within the covalent complex. In the case of TEM‐1, such unfavorable interactions convert substrate analogues into very effective inhibitors. Proteins 2002;47:86–96. © 2002 Wiley‐Liss, Inc.
Refining structural and functional predictions for secretasome components by comparative sequence analysis
Authors: Mushegian Arcady
Published: October 2004

Comparative sequence analysis of presenilins reveals the conserved transmembrane domain shared with leukocyte antigen CD47, possibly involved in signal transduction. Sensitive techniques of multiple sequence alignment extend the earlier observation of the aminopeptidase homology domain in nicastrin to suggest that this protein may be a catalytically active component of secretasome involved in proteolysis or co‐proteolysis of presenilin or β‐amyloid. Proteins 2002;47:69–74. © 2002 Wiley‐Liss, Inc.
Water in protein cavities: A procedure to identify internal water and exchange pathways and application to fatty acid‐binding protein
Authors: Bakowies Dirk , van Gunsteren Wilfred F.
Published: October 2004

A computational approach based on Delaunay triangulation is presented to identify internal water molecules in proteins and to capture pathways of exchange with the bulk. The implemented procedure is computationally efficient and can easily be applied to long molecular dynamics trajectories of protein simulations. In an application to fatty acid‐binding protein in apo‐form and with bound palmitate, several protein orifices known from crystal structures have been confirmed to be major portals of solvent exchange. Differences between the two forms of the protein are observed and discussed. Proteins 2002;47:534–545. © 2002 Wiley‐Liss, Inc.
Conformational polymorphism of wild‐type and mutant prion proteins: Energy landscape analysis
Authors: Levy Yaakov , Becker Oren M.
Published: October 2004

Conformational transitions are thought to be the prime mechanism of prion diseases. In this study, the energy landscapes of a wild‐type prion protein (PrP) and the D178N and E200K mutant proteins were mapped, enabling the characterization of the normal isoforms (PrPC) and partially unfolded isoforms (PrPPU) of the three prion protein analogs. It was found that the three energy landscapes differ in three respects: (i) the relative stability of the PrPC and the PrPPU states, (ii) the transition pathways from PrPC to PrPPU, and (iii) the relative stability of the three helices in the PrPC state. In particular, it was found that although helix 1 (residues 144‐156) is the most stable helix in wild‐type PrP, its stability is dramatically reduced by both mutations. This destabilization is due to changes in the charge distribution that affects the internal salt bridges responsible for the greater stability of this helix in wild‐type PrP. Although both mutations result in similar destabilization of helix 1, they a have different effect on the overall stability of PrPC and of PrPPU isoforms and on structural properties. The destabilization of helix 1 by mutations provides additional evidences to the role of this helix in the pathogenic transition from the PrPC to the pathogenic isoform PrPSC. Proteins 2002;47:458–468. © 2002 Wiley‐Liss, Inc.
Solution structure and backbone dynamics of an antigen‐free heavy chain variable domain (VHH) from Llama
Authors: Renisio Jean‐Guillaume , Pérez Janice , Czisch Michael , Guenneugues Marc , Bornet Olivier , Frenken Leon , Cambillau Christian , Darbon Hervé
Published: October 2004

Camelids, (dromedaries, camels, and llamas) produce heavy‐chains antibodies, with their antigen recognition sites composed of a single VH‐like domain, referred to as VHH. The solution structure of one of these VHHs domains (VHH‐H14), raised against the α subunit of the human chorionic gonadotropin hormone (hCG), has been determined by 15N heteronuclear three‐dimensional NMR spectroscopy. The framework is well resolved within the set of 20 best‐calculated NMR structures and is close to that of classical VH domains from vertebrate antibodies, consisting of two antiparallel β‐sheets organized in a β‐barrel. Loops display a lower precision, especially the Complementarity Determining Regions (CDRs), involved in antigen recognition. Comparison of the three‐dimensional VHH‐H14 solution structure with its previously solved crystal structure (Spinelli et al., Nature Struct. Biol. 1996;3:752–757) reveals a high similarity to the framework, whereas significant conformational differences occur on CDRs, leading to the assumption that the antigen recognition site is a more mobile part. In order to deepen our insights into the dynamics of VHH‐H14 in solution, 15N relaxation was measured with longitudinal R1 and transverse R2 self‐relaxation rates, and 15N steady‐state heteronuclear nuclear Overhauser enhancements (NOE), making it possible to probe picosecond‐to‐millisecond internal motions. Determination of dynamic parameters (S2, τe, and Rex) through the Lipari‐Szabo Model‐free approach enables the identification of several regions with enhanced dynamics. Especially, the mobility measurements from NMR confirm that the antigen recognition site is the most mobile part of the VHH‐H14 domain on picosecond‐to‐nanosecond fast time scales. Several residues belonging to the three CDRs are submitted to chemical exchange processes occurring on slow microsecond‐to‐millisecond time scales, suggesting that the formation of the VHH/antigen complex should be accompanied by structural changes. Proteins 2002;47:546–555. © 2002 Wiley‐Liss, Inc.
Principles of docking: An overview of search algorithms and a guide to scoring functions
Authors: Halperin Inbal , Ma Buyong , Wolfson Haim , Nussinov Ruth
Published: October 2004

The docking field has come of age. The time is ripe to present the principles of docking, reviewing the current state of the field. Two reasons are largely responsible for the maturity of the computational docking area. First, the early optimism that the very presence of the “correct” native conformation within the list of predicted docked conformations signals a near solution to the docking problem, has been replaced by the stark realization of the extreme difficulty of the next scoring/ranking step. Second, in the last couple of years more realistic approaches to handling molecular flexibility in docking schemes have emerged. As in folding, these derive from concepts abstracted from statistical mechanics, namely, populations. Docking and folding are interrelated. From the purely physical standpoint, binding and folding are analogous processes, with similar underlying principles. Computationally, the tools developed for docking will be tremendously useful for folding. For large, multidomain proteins, domain docking is probably the only rational way, mimicking the hierarchical nature of protein folding. The complexity of the problem is huge. Here we divide the computational docking problem into its two separate components. As in folding, solving the docking problem involves efficient search (and matching) algorithms, which cover the relevant conformational space, and selective scoring functions, which are both efficient and effectively discriminate between native and non‐native solutions. It is universally recognized that docking of drugs is immensely important. However, protein–protein docking is equally so, relating to recognition, cellular pathways, and macromolecular assemblies. Proteins function when they are bound to other molecules. Consequently, we present the review from both the computational and the biological points of view. Although large, it covers only partially the extensive body of literature, relating to small (drug) and to large protein–protein molecule docking, to rigid and to flexible. Unfortunately, when reviewing these, a major difficulty in assessing the results is the non‐uniformity in the formats in which they are presented in the literature. Consequently, we further propose a way to rectify it here. Proteins 2002;47:409–443. © 2002 Wiley‐Liss, Inc.
Calculated geometries of dications of bis odd‐membered π‐ring systems containing a NCN fragment and related π‐systems. An opposite out‐of‐plane rotation of the 4nπ‐ring subsystems
Authors: Buck Henk
Published: October 2004

Quantum chemical calculations have been carried out on dications of bis odd‐membered π‐ring systems containing a NCN fragment and related π‐systems. An opposite out‐of‐plane rotation of both subsystems was found if these systems contain 4nπ‐electrons (antiaromatic). A planar situation was found for 4n+2 π‐electrons (aromatic). The geometric representations could be compared with X‐ray crystallographic three‐dimensional structures of related compounds. Calculations at different levels clearly show that separation of the σ‐ and π‐electron contribution is an effective way to elucidate the origin of the geometrical changes. We also give attention to some fundamental aspects of the subsystems related to the 1,3‐azolium cations because of their biochemical relevance such as fast C2H proton exchange. We postulate that at least two molecules of water are involved in this process. The significance of a trigonal pyramidal (TP) geometry has been emphasized. © 2001 Wiley Periodicals, Inc. Int J Quantum Chem, 2001
Computing the Kekulé structure count for alternant hydrocarbons
Authors: Torrens F.
Published: October 2004

A fast computer algorithm brings computation of the permanents of sparse matrices, specifically, molecular adjacency matrices. Examples and results are presented, along with a discussion of the relationship of the permanent to the Kekulé structure count. A simple method is presented for determining the Kekulé structure count of alternant hydrocarbons. For these hydrocarbons, the square of the Kekulé structure count is equal to the permanent of the adjacency matrix. In addition, for alternant structures the adjacency matrix for N atoms can be written in such a way that only an N/2 × N/2 matrix need be evaluated. The Kekulé structure count correlates with topological indices. The inclusion of the number of cycles improves the fit. When comparing with previous results, the variance decreases 74%. The calculated standard heat of formation correlates with the logarithm of the Kekulé structure count. This heat increments 349 kJ/mol each time the Kekulé structure count increases by one order of magnitude. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Potential energy surfaces of fluorobenzene radical anions
Authors: Beregovaya Irina V. , Shchegoleva Lyudmila N.
Published: October 2004

Ab initio ROHF/6‐31+G* and MP2/6‐31+G*//ROHF/6‐31+G* calculations were used to consider fluorination's effect on potential energy surfaces (PESs) of benzene radical anion's (RAs). The Hartree–Fock PESs of symmetrically fluorinated radical anions were found to be pseudorotation surfaces. Unlike the benzene anion PES, pseudorotation surfaces include nonplanar structures. A Möbius band may represent the pseudorotation scheme of C6H stationary structures. Cutting the band out, we may obtain a pseudorotation scheme peculiar to C6F. This way of PES scheme building is also applicable to partially fluorinated RAs. A complicated structure of fluorinated anions' PES results from the avoided crossing of π states closed in energy together with the presence of a low‐lying vibronically active excited σ state. The number of stationary structures involved in pseudorotation varies in the series of anions, and may be changed at a higher level of calculations. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
A graphical scheme for representing many‐electron spin‐free configurations
Authors: Sarma C. R. , Shankar N. Ravi , Rettrup S.
Published: October 2004

The present approach is a graphical technique for representing and generating primitive configurations of space orbitals for electronic systems. The graph is developed as a tree whose paths define the allowed space configurations of electrons admitting at most double occupancy for each orbital. The emphasis in the graph is on the nodes representing occupied orbitals rather than on the arcs compared with previous graphical procedures used in graphical unitary and symmetric group approaches. This leads to a compact representation of the orbital configurations and provides a computationally very efficient indexing scheme. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Ab initio through‐space/bond interaction analysis of the long C–C bonds in Bi(anthracene‐9,10‐dimethylene) photoisomers
Authors: Orimoto Yuuichi , Aoki Yuriko
Published: October 2004

The bi(anthracene‐9,10‐dimethylene) photoisomer has remarkably long C–C single bonds. To examine the lengthening of the C–C bond, we propose a novel procedure for quantitatively analyzing orbital interactions in a molecule at the level of the ab initio molecular orbital method. In this procedure, we can cut off the specific through‐space/bond interactions in a molecule by artificially increasing the absolute magnitude of the exponents in a Gaussian function. Then, the spatial orbital interactions were perfectly cut off, and, each term that makes up the total energy, that is, the nuclear–electron attractions, the electron–electron repulsions, and the nuclear–nuclear repulsions cancel each other. Several model molecules of the photoisomer were analyzed by this procedure. It was found that the orbital interaction between the p orbital on the benzene ring and the σ* orbital on the C–C bond in question, σ→σ* electron transfer through π orbital, weakens the C–C bond efficiently when these orbitals were located in the “periplanar” conformation. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Simultaneous determination of nuclear and electronic wave functions without Born–Oppenheimer approximation: Ab initio NO+MO/HF theory
Authors: Nakai Hiromi
Published: October 2004

We develop a simultaneous determination method of nuclear and electronic wave functions without the Born–Oppenheimer approximation. We examine two expanding methods, namely, molecular orbital (MO)‐type and valence bond (VB)‐type expansions for a nuclear orbital, which is a one‐particle wave function of a nucleus. The VB‐type expansion is shown to be more accurate than the MO‐type one because of the local nature of the nuclei. We also investigate the basis function expansion of the nuclear orbital and propose a scheme to determine the orbital exponent for the nuclear basis function. Numerical calculations confirm the accuracy and feasibility of the present method. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Surface segregation in bimetallic nanoclusters: Geometric and thermodynamic effects
Authors: Mainardi Daniela S. , Balbuena Perla B.
Published: October 2004

Nanocluster morphology (size, crystallographic faces, surface defects), coupled to thermodynamic driving forces, influence surface segregation phenomena. These geometric and thermodynamic effects are studied at several temperatures and overall compositions for Cu–Ni, Ag–Cu, and Ag–Rh. The bond order metal simulation model [Zhu, L.; DePristo, A. E. J Catal 1997, 167, 400] is used in Monte Carlo simulations to describe interatomic interactions. Nanoclusters from 110 to 729 atoms are arranged on stacks of layers corresponding to face‐centered cubic crystals. The exposed surfaces are (111), (110), and (331) faces, and the overall composition of the clusters defined in terms of the segregating atoms ranges from 5 to 95%. The effect of surface steps on surface segregation is also investigated. It is found that as overall concentration increases, the effect of surface defects on segregation phenomena becomes more pronounced. The increase in the number of low coordination sites due to the presence of surface steps modifies the layer‐by‐layer composition profile, causing surface and inner sites in the proximity of the step to become occupied by the segregating atoms. The population on other surfaces becomes depleted, resulting in a lowered total surface segregation. These effects are more noticeable not only at high overall composition but also at high temperatures, especially for the less segregating system, Ag–Cu. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Geometries and electronic structures of W4 and W clusters
Authors: Wang J. P. , Niu C. J. , Wu Z. J.
Published: October 2004

Geometries and electronic structures of W4 and W clusters were studied by use of density functional methods B3LYP, B3P86, B3PW91, BHLYP, BLYP, and MPW1PW91. The calculated results indicate that the three‐dimensional structure of singlet state with either D2d symmetry (B3LYP, B3P86, B3PW91, BLYP, and MPW1PW91) or C2v symmetry (BHLYP) is the ground state for the W4 cluster. For the W cluster, the doublet state is preferred, and the most stable structure is also 3D with either D2d symmetry (B3LYP, B3PW91, BHLYP, BLYP) or C2v symmetry (B3P86 and MPW1PW91). The calculated electron affinity at B3P86 gives the best performance compared with experiment. For the dissociation channel, W + W3 is suggested to be the possible route for the W4 cluster. For the W cluster, W + W is the most likely route for dissociation, in agreement with experiment. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Van der Waals density functional theory with applications
Authors: Langreth D. C. , Dion M. , Rydberg H. , Schröder E. , Hyldgaard P. , Lundqvist B. I.
Published: October 2004

The details of a density functional that includes van der Waals (vdW) interactions are presented. In particular we give some key steps of the transition from a form for fully planar systems to a procedure for realistic layered compounds that have planar symmetry only on large‐distance scales, and which have strong covalent bonds within the layers. It is shown that the random‐phase approximation of that original functional can be replaced by an approximation that is exact at large separation between vdW interacting fragments and seamless as the fragments merge. An approximation to the latter which renders the functional easily applicable and which preserves useful accuracy in both limits and in between is given. We report additional data from applications to forms of graphite, boron nitride, and molybdenum sulfide not reported in our previous communication. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Systemic administration of 1R,4S‐4‐amino‐cyclopent‐2‐ene‐carboxylic acid, a reversible inhibitor of GABA transaminase, blocks expression of conditioned place preference to cocaine and nicotine in rats
Authors: Ashby Charles R. , Paul Mousumi , Gardner Eliot L. , Gerasimov Madina R. , Dewey Stephen L. , Lennon Ian C. , Taylor Stephen J.C.
Published: October 2004

We examined the effect of 1R,4S‐4‐amino‐cyclopent‐2‐ene‐carboxylic acid (ACC), a reversible inhibitor of GABA transaminase, on the expression of conditioned place preference response to cocaine and nicotine in rats. Cocaine (20 mg/kg i.p.) and nicotine (0.4 mg/kg s.c.), but not vehicle or 300 mg/kg i.p. of ACC, produced a significant conditioned place preference response. Pretreatment of animals with 300 and 75 mg/kg i.p. of ACC significantly attenuated the expression of the cocaine‐ and nicotine‐induced conditioned place preference responses, respectively. These results are the first to suggest that reversible inhibition of GABA transaminase may be useful in blocking cue‐induced relapse to nicotine and cocaine. Synapse 44:61–63, 2002. © 2002 Wiley‐Liss, Inc.
Geometric morphometrics of corpus callosum and subcortical structures in the fetal‐alcohol‐affected brain
Authors: Bookstein Fred L. , Sampson Paul D. , Streissguth Ann P. , Connor Paul D.
Published: October 2004

Background

Although experienced clinicians have been diagnosing fetal alcohol syndrome (FAS) for nearly 30 years, the rest of the spectrum of fetal alcohol damage is not being classified effectively. This article describes a quantification of neuroanatomical structure that may supply a useful discriminator of prenatal brain damage from alcohol. It is demonstrated in a data set of adults of both sexes.

Methods

Ninety adults (45 males) were examined by magnetic resonance imaging (MRI). These subjects were group‐matched for age and ethnicity across three diagnoses: FAS, fetal alcohol effects (FAE), and normals. All FAS and FAE were heavily alcohol‐exposed in utero; normals were not. From T1‐weighted MR brain images, we extracted 3D morphometric representations of shape for 33‐landmark point configurations and 40‐point outlines of the corpus callosum along its midline (a slightly nonplanar structure).

Results

There are striking differences between exposed and unexposed in the statistical distributions of these two shapes. The differences are better characterized by excess variance in the exposed group than by any change in average landmark or outline shape. For each sex, combining the callosal outline data with the landmark data leads to a powerful quadratic discriminator of exposed from unexposed. The discriminating features include the relationship of brain stem to diencephalon, and localized variabilities of callosal outline shape, but not diagnosis (FAS vs. FAE).

Conclusions

Statistical analysis of brain shape is a powerful new source of information relevant to fetal alcohol spectrum nosology and etiology. Patients with FAS and FAE do not differ in these brain shape features, but both differ from the unexposed. The aspects of brain shape that are especially variable may be entailed in the underlying neuroteratogenetic mechanisms. Teratology 64:4–32, 2001. © 2001 Wiley‐Liss, Inc.
Effect of early fetal irradiation on the postnatal development of mouse
Authors: Uma Devi P. , Hossain M.
Published: October 2004

Background

An earlier study has shown that irradiation at the late fetal stage of Swiss albino mice disturbed postnatal growth and appearance of physiological markers. The present study was done to determine the effect of irradiation at the early fetal stage on the postnatal development of mouse.

Methods

Fourteen‐day pregnant Swiss albino mice were exposed to 0.1–1.5 Gy of cobalt‐60 γ‐rays. F1 pups were observed for ≤6 weeks of age. Postnatal mortality, body weight and length, head length and width, tail length, and the time of appearance of physiological markers (pinna detachment, eye opening, fur development, vaginal opening and testes descent) were noted.

Results

There was no increase in congenital anomalies. Postnatal mortality and percentage of growth‐retarded pups increased significantly at doses of 0.5–1.5 Gy. A significant delay in the appearance of all the physiological markers was also noted at these doses. Body length, head length, and tail length remained significantly lower than in the controls throughout the observation period at doses of 0.3–1.5 Gy, whereas body weight and head width showed such a persistent change only at ≥0.5 Gy.

Conclusions

The early fetal day 14 in mouse is sensitive to radiation‐induced postnatal mortality and impairment of growth and temporal development of physiological markers, but not to induction of congenital anomalies. While mortality and physiological markers are not affected at <0.5 Gy, growth retardation appears to have a lower threshold of ∼0.3 Gy. Teratology 64:45–50, 2001. © 2001 Wiley‐Liss, Inc.
Career management issues for flexpatriate international staff
Authors: Mayerhofer Helene , Hartmann Linley C. , Herbert Anne
Published: October 2004

This article reports findings from an in‐depth study of a small number of European men and women that identifies organizational activities and their own initiatives to successfully manage their international careers within the context of their personal and family lives. In contrast to prior studies that have focused on issues for expatriate international work assignments, this study focused on flexpatriates—the frequent flyers of international work. The results indicated that, with minimal human resource management (HRM) assistance, flexpatriates were proactive and self‐managing in dealing with career issues and the family and personal demands linked to their flexpatriate lifestyles. Similar career issues were evident for men and women, but the impact of home life seemed more significant for women, and the implications of this for HRM are explored. © 2004 Wiley Periodicals, Inc.
Expatriate selection: An empirical study identifying significant skill profiles
Authors: Graf Andrea
Published: October 2004

Effective selection procedures constitute an important factor in increasing expatriate success. However, research lacks findings regarding which skills to screen in international selection processes and whether to base expatriate selection on a culture‐specific or culture‐general skill profile. In an attempt to gather such evidence, an empirical study was conducted in the United States and Germany. Managers in both nations judge intercultural communication skills and intercultural sensitivity to be important intercultural competencies. Moreover, culture‐specific skills seem to be required when engaged in both a U.S. and German working context. Recommendations for complementing culture‐general and culture‐specific skill profiles are discussed. © 2004 Wiley Periodicals, Inc.
Attitudes toward foreign assignments among Danish economists
Authors: Andersen Torben , Scheuer Steen
Published: October 2004

This article addresses attitudinal issues toward foreign assignments and reports on data collected from a distinct sample of respondents—Danish economists. One of the much‐debated questions is whether foreign assignments are becoming less attractive, in particular among the younger employees, who tend to follow more narrow self‐interests and stay home. This is supposed to be reinforced by deteriorating corporate policies (i.e., offers being less attractive). The present study provides the basis for rather significant findings. The economists tend to look quite positively on expatriation (across age, gender, seniority, former foreign assignment, and unemployment), and this finding is supported by the fact that about 25% of the respondents already had experiences with foreign assignment. © 2004 Wiley Periodicals, Inc.
An empirical study of executive nationality staffing practices in foreign‐owned MNC subsidiaries in Ireland
Authors: Thompson Karen , Keating Mary
Published: October 2004

This study provides empirical evidence of executive nationality staffing practices in foreign‐owned multinational company (MNC) subsidiaries in Ireland. Aiming to both describe current practice and understand the factors that influence the choice of practice, the study involved the collection of data from 238 foreign‐owned companies in Ireland. The findings negate previous findings (Harzing, 1999a, b) that all foreign‐owned MNC subsidiaries in Ireland are managed by Irish nationals. The employment of parent country nationals was found to differ according to country‐of‐origin, industry, subsidiary, and MNC factors. The study has relevance theoretically in providing empirical evidence in an area dominated by conceptual assertions and for practice in explaining the strategic staffing decisions of MNCs. © 2004 Wiley Periodicals, Inc.
Breastfeeding and the Risk of Childhood Leukemia: A Meta-Analysis
Authors: Kwan Marilyn L. , Buffler Patricia A. , Abrams Barbara , Kiley Vincent A.
Published: October 2004

Objectives.

The authors used a meta-analytic technique to ( 1) quantify the evidence of an association between duration of breastfeeding and risk of childhood acute lymphoblastic leukemia (ALL) or acute myeloblastic leukemia (AML), ( 2) assess the influence of socioeconomic status (SES) on any such associations, and ( 3) discuss the implications of these findings for the evaluation of whether breastfeeding reduces the risk of childhood leukemia.

Methods.

A fixed effects model was employed to systematically combine the results of 14 case-control studies addressing the effect of short-term (⩽6 months) and long-term (>6 months) breastfeeding on the risk of childhood ALL and/or AML. Subgroup analyses of studies that did and did not adjust for SES were also performed.

Results.

A significant, negative association was observed between long-term breastfeeding and both ALL risk (odds ratio [OR] = 0.76; 95% confidence interval [CI] 0.68, 0.84) and AML risk (OR=0.85; 95% CI 0.73, 0.98). Short-term breastfeeding was similarly protective for ALL and AML. Results for studies that adjusted and did not adjust for SES were not significantly different from the results for the 14 studies combined.

Conclusions.

This meta-analysis showed that both short-term and long-term breastfeeding reduced the risk of childhood ALL and AML, suggesting that the protective effect of breastfeeding might not be limited to ALL as earlier hypothesized. Potential bias introduced by different participation rates for case and control samples that differed in SES can be minimized by implementing larger case-control studies with SES-matched, population-based controls.
What's Going on? The Question of Time Trends in Autism
Authors: Blaxill Mark F.
Published: October 2004

Increases in the reported prevalence of autism and autistic spectrum disorders in recent years have fueled concern over possible environmental causes. The author reviews the available survey literature and finds evidence of large increases in prevalence in both the United States and the United Kingdom that cannot be explained by changes in diagnostic criteria or improvements in case ascertainment. Incomplete ascertainment of autism cases in young child populations is the largest source of predictable bias in prevalence surveys; however, this bias has, if anything, worked against the detection of an upward trend in recent surveys. Comparison of autism rates by year of birth for specific geographies provides the strongest basis for trend assessment. Such comparisons show large recent increases in rates of autism and autistic spectrum disorders in both the U.S. and the U.K. Reported rates of autism in the United States increased from <3 per 10,000 children in the 1970s to >30 per 10,000 children in the 1990s, a 10-fold increase. In the United Kingdom, autism rates rose from <10 per 10,000 in the 1980s to roughly 30 per 10,000 in the 1990s. Reported rates for the full spectrum of autistic disorders rose from the 5 to 10 per 10,000 range to the 50 to 80 per 10,000 range in the two countries. A precautionary approach suggests that the rising incidence of autism should be a matter of urgent public concern.
Hospital Recruitment for the Smallpox Pre-Event Vaccination Program: Experiences from Florida, Nebraska, New Jersey, and Tennessee, December 2002–June 2003
Authors: Ching Pamela , Tynan William P. , Raymond Dick , Bresnitz Eddy , Craig Allen S.
Published: October 2004

The Smallpox Pre-Event Vaccination Program (SPVP) for public health and hospital-based health care workers began on January 24, 2003. This report summarizes efforts made by health officials in Florida, Nebraska, New Jersey, and Tennessee to facilitate the voluntary participation of acute care hospitals in the SPVP. Seven common characteristics contributed to the success of programs in these four states: ( 1) early planning, building on existing competencies, and state government support, ( 2) carrying the program forward on a planned timeline with experienced vaccination staff, ( 3) use of multifaceted training activities, ( 4) use of mock scenarios and field exercises to avoid early problems, ( 5) establishment and fostering of good relationships and lines of communication with stakeholders and the mass media, ( 6) addressing liability and workers' compensation concerns prior to initiation of the SPVP, and ( 7) attention to vaccination clinic logistics.
Physical Partner Violence and Medicaid Utilization and Expenditures
Authors: Coker Ann L. , Reeder C. Eugene , Fadden Mary Kay , Smith Paige H.
Published: October 2004

Objectives.

Little research has addressed differences in health care expenditures among women who are currently experiencing intimate partner violence (IPV) compared with those who are not. The purpose of this work is to provide estimates of direct medical expenditure for physician, drug, and hospital utilization among Medicaid-eligible women who screened as currently experiencing IPV compared with those who are not currently experiencing IPV.

Methods.

In this family practice-based cross-sectional study, women were screened for current IPV using a 15-item Index of Spouse Abuse–Physical (ISA-P) between 1997 and 1998. Consents were obtained from study subjects to review Medicaid expenditure and utilization data for the same time period.

Results.

Mean physician, hospital, and total expenditures were higher for those women with higher IPV scores compared with those who scored as not currently experiencing IPV, after adjusting for confounders. Higher IPV scores were associated with a three-fold increased risk of having a total expenditure over $5,000 (95% confidence interval [CI] 1.3, 8.4). The mean total expenditure difference between the high IPV and no IPV groups was $1,064 (95% CI $623, $1506). The adjusted risk ratio for high IPV score and the log of total Medicaid expenditures was 2.3 (95% CI 1.2, 4.4).

Conclusions.

Women screened as experiencing higher IPV scores had higher Medicaid expenditures compared with women not currently experiencing IPV. Early IPV assessment partnered with effective clinic or community-based interventions may help to identify IPV earlier and reduce the health impact and cost of IPV.
Household Food Security among Migrant and Seasonal Latino Farmworkers in North Carolina
Authors: Quandt Sara A. , Arcury Thomas A. , Early Julie , Tapia Janeth , Davis Jessie D.
Published: October 2004

Objective.

Food insecurity is defined as lack of access at all times, due to economic barriers, to enough food for an active and healthy lifestyle. The objective of this study was threefold: to characterize levels of food security, food insecurity, and hunger among migrant and seasonal Latino farmworkers; to assess predictors of food insecurity for this group; and to describe the strategies farmworkers use to cope with food insecurity.

Methods.

Adults from 102 farmworker households in North Carolina responded to a survey that used a Spanish-language adaptation of the U.S. Household Food Security Survey Module and questions about sociodemographic characteristics and food behaviors. Twenty-five farmworkers participated in in-depth interviews in which they described their households' food security situation and coping strategies.

Results.

Forty-eight of the 102 sample households (47.1%) were classified as food insecure, including 10 (9.8%) with moderate hunger and five (4.9%) with severe hunger. Households with children had a significantly higher prevalence of food insecurity than those without children (56.4% vs. 36.2%). Households with children accessed food programs such as the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) that were unavailable to those without children, while those without children were more likely to access food pantries and to consume wild game or fish. Coping strategies included borrowing money, reducing food variety, and adults consuming less food to protect children from hunger. Food insecurity was more than four times as prevalent among farmworker households as among the general U.S. population.

Conclusion.

Policy changes to increase economic resources and access to federal programs are needed to decrease this food insecurity.