bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, Isolation and Structural Investigation of Schiff‐Base Alkoxytitanium Complexes: Steric Limitations of Ligand Coordination
Authors: Johnson Andrew L. , Davidson Matthew G. , Lunn Matthew D. , Mahon Mary F. 
Published: June 2006

AbstractThis paper reports the reaction of Ti(OiPr)4 with a series of Schiff‐base ligands. The Schiff‐base proligands 1a–l are synthesised by the condensation of salicylaldehyde with a range of primary alkylamine and aniline derivatives. The treatment of 1a–f with Ti(OiPr)4 yields the octahedral bis(aryloxy–imine)Ti(OiPr)2 complexes 2a–f. X‐ray crystal structure analysis of 2c, 2d and 2e reveals complexes with a trans‐aldiminato oxygen atom and cis‐N,cis‐alkoxide ligand arrangement about the central metal atom. The reactions of Ti(OiPr)4 with the ligands 1g and 1h result in a sterically induced ligand rearrangement to form the octahedral complexes 2g and 2h, also characterised by X‐ray diffraction experiments, in which the nitrogen atoms of the O,N‐chelate are now trans‐orientated at the titanium centre. 1H NMR analysis reveals significant deshielding of the isopropoxide methine proton, induced by this coordination mode. In contrast, reactions of 1i and 1j with Ti(OiPr)4 result in the formation and isolation of the complexes 2i and 2j. X‐ray crystal structure analysis shows complex 2j to have a previously unobserved ligand orientation, in which both ligands are trans‐orientated, with respect to the aldiminato oxygen atoms, about the titanium centre, but steric bulk of the ligand inhibits the bidentate coordination of both O,N‐ligands. Further increase in thesteric bulk of the imine substituent results in a reduced reactivity for ligands 1k and 1l, such that Ti(OiPr)4 reacts with 1k to form the dimeric mono(Schiff‐base) complex 2k (characterised by X‐ray analysis). No reaction is observed for 1l. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Growth curve models for stochastic modeling and analyzing of natural disinfection of wastewater
Authors: Bischoff Wolfgang , Huang Mong‐Na Lo , Yang Lei 
Published: June 2006

AbstractThis work is motivated by a study on the natural disinfection of wastewater in marine environment for ocean outfall systems without chlorination. In the study of the disinfection on wastewater in marine environment two natural factors, consisting of light intensity and salinity, one controllable factor, the volumetric mixing ratio of seawater to wastewater, and one random effect factor, the existence of predators, were investigated. Our problem and data are modeled by a growth curve model with an unknown random parameter that can be described by a mixed model with the factors mentioned above as covariates. For our model we determine the optimal variance estimations. Finally, we apply our model with these optimal estimated variance components to the data obtained from the real experiments. Copyright © 2006 John Wiley & Sons, Ltd.
Resampling‐based multiple hypothesis testing procedures for genetic case‐control association studies
Authors: Chen Bingshu E. , Sakoda Lori C. , Hsing Ann W. , Rosenberg Philip S. 
Published: June 2006

AbstractIn case‐control studies of unrelated subjects, gene‐based hypothesis tests consider whether any tested feature in a candidate gene—single nucleotide polymorphisms (SNPs), haplotypes, or both—are associated with disease. Standard statistical tests are available that control the false‐positive rate at the nominal level over all polymorphisms considered. However, more powerful tests can be constructed that use permutation resampling to account for correlations between polymorphisms and test statistics. A key question is whether the gain in power is large enough to justify the computational burden. We compared the computationally simple Simes Global Test to themin Ptest, which considers the permutation distribution of the minimump‐value from marginal tests of each SNP. In simulation studies incorporating empirical haplotype structures in 15 genes, themin Ptest controlled the type I error, and was modestly more powerful than the Simes test, by 2.1 percentage points on average. When disease susceptibility was conferred by a haplotype, themin Ptest sometimes, but not always, under‐performed haplotype analysis. A resampling‐based omnibus test combining themin Pand haplotype frequency test controlled the type I error, and closely tracked the more powerful of the two component tests. This test achieved consistent gains in power (5.7 percentage points on average), compared to a simple Bonferroni test of Simes and haplotype analysis. Using data from the Shanghai Biliary Tract Cancer Study, the advantages of the newly proposed omnibus test were apparent in a population‐based study of bile duct cancer and polymorphisms in the prostaglandin‐endoperoxide synthase 2 (PTGS2)gene.Genet. Epidemiol.2006. Published 2006 Wiley‐Liss, Inc.
Effects of calcium chloride treatments on wheat grain peroxidase activity and outer layer mechanical properties
Authors: Desvignes Claire , Olivé Caroline , Lapierre Catherine , Rouau Xavier , Pollet Brigitte , Lullien‐Pellerin Valerie 
Published: June 2006

AbstractWheat grain soaking in calcium solutions was used as a tool to enhance endogenous peroxidase activities and follow potential changes in outer layer mechanical properties and cell wall phenolic profile. Treatment with 10 mmol L−1 calcium chloride was found to increase peroxidase activities in grains from two cultivars differing in kernel hardness, but at a different level. Concomitantly, mechanical properties of the outer layers from treated grains, assessed by uniaxial tension tests, showed significant stiffening depending on wheat cultivar. These changes were also observed in tissues after removal of the outer pericarp but not in each of the isolated layers, suggesting that modification of the mechanical properties occurs at the interface between the aleurone layer and the surrounding tissues. Analyses of the outer layer phenolic acid composition after mild or severe alkaline hydrolysis and of released lignin monomers after thioacidolysis appeared in accordance with the observed changes in tissue mechanical properties and suggest modification of cell wall compound interactions. Copyright © 2006 Society of Chemical Industry
Polyester Scaffolds with Bimodal Pore Size Distribution for Tissue Engineering
Authors: Sosnowski Stanislaw , Woźniak Piotr , Lewandowska‐Szumieł Małgorzata 
Published: June 2006

AbstractSummary: This paper presents a method for the preparation of porous poly(L‐lactide)/poly[(L‐lactide)‐co‐glycolide] scaffolds for tissue engineering. Scaffolds were prepared by a mold pressing‐salt leaching technique from structured microparticles. The total porosity was in the range 70–85%. The pore size distribution was bimodal. Large pores, susceptible for osteoblasts growth and proliferation had the dimensions 50–400 µm. Small pores, dedicated to the diffusion of nutrients or/and metabolites of bone forming cells, as well as the products of hydrolysis of polyesters from the walls of the scaffold, had sizes in the range 2 nm–5 µm. The scaffolds had good mechanical strength (compressive modulus equal to 41 MPa and a strength of 1.64 MPa for 74% porosity). Scaffolds were tested in vitro with human osteoblast‐like cells (MG‐63). It was found that the viability of cells seeded within the scaffolds obtained using the mold pressing‐salt leaching technique from structured microparticles was better when compared to cells cultured in scaffolds obtained by traditional methods. After 34 d of culture, cells within the tested scaffolds were organized in a tissue‐like structure.Photos of section of macro‐ and mesoporous PLLA/PLGA scaffold containing 50 wt.‐% of PLGA microspheres after 34 d of culture. Dark spots mark MG‐63 cells, white areas belong to the scaffold. The specimen was stained with haematoxylin/eosin. Bar = 100 µm.magnified imagePhotos of section of macro‐ and mesoporous PLLA/PLGA scaffold containing 50 wt.‐% of PLGA microspheres after 34 d of culture. Dark spots mark MG‐63 cells, white areas belong to the scaffold. The specimen was stained with haematoxylin/eosin. Bar = 100 µm.
Preparation and Characterization of Poly(N‐isopropylacrylamide)‐modified Poly(2‐hydroxyethyl acrylate) Hydrogels by Interpenetrating Polymer Networks for Sustained Drug Release
Authors: Liu Yu‐Yang , Lü Jian , Shao Ying‐Hui 
Published: June 2006

AbstractSummary: In order to investigate the influence of hydrophobic moieties formed by poly(N‐isopropylacrylamide) (PNIPAm) in a hydrogel matrix on the release behavior of the hydrogel, a series of poly(N‐isopropylacrylamide) (PNIPAm)‐modified poly(2‐hydroxyethyl acrylate‐co‐2‐hydroxyethyl 2‐hydroxyethyl methacrylate) (P(HEA‐co‐HEMA)) via interpenetrating polymer networks (IPNs) were prepared by a sequential UV solution polymerization. Interestingly, it was found that P(HEA‐co‐HEMA)/PNIPAm IPN indicated a single glass transition temperature (Tg) and the Tgs of the IPNs increased with an increase in the PNIPAm component. This phenomenon may be attributed to hydrogen bonding between the two polymer networks, but the hydrogen bonding exerts less influence on the swelling behavior of the IPNs, due to the fact that IPNs can respond to changes in temperature like PNIPAm. Using 2‐[(diphenylmethyl)sulphiny]acetamide (modafinil, MOD) and p‐hydroxybenzoic acid (HBA) as model drug compounds, the release behavior of the IPNs was studied at body temperature, and it was found that the presence of PNIPAm could retard drug release regardless of the solubility of the drugs.Release profiles of HBA from the IPNs and their component samples as a function of time at 37 °C.magnified imageRelease profiles of HBA from the IPNs and their component samples as a function of time at 37 °C.
Effect of Clay Type on Structure and Properties of Poly(methyl methacrylate)/Clay Nanocomposites
Authors: Si Mayu , Goldman Michael , Rudomen Gregory , Gelfer Mikhail Y. , Sokolov Jonathan C. , Rafailovich Miriam H. 
Published: June 2006

AbstractSummary: PMMA nanocomposites using natural Cloisite 6A and synthetic Lucentite SPN clays were produced via melt blending. The degree of intercalation or exfoliation was measured for both composites using transmission electron microscopy (TEM) and the results were confirmed with small angle X‐ray scattering (SAXS). The smaller dimensions of the synthetic SPN, as well as the complete absence of Fe ion impurities allowed for the production of a composite which was optically clear and completely colorless. TEM and SAXS measurements were performed on samples heated to high temperatures. The data showed that in both cases large ribbons composed of the individual platelets were formed. We postulated that these ribbons formed a barrier against spreading of the flame and hence the smaller clays, which are more mobile, had a higher efficiency.TEM image of a high degree of exfoliation of synthetic clay SPN in the PMMA matrix.magnified imageTEM image of a high degree of exfoliation of synthetic clay SPN in the PMMA matrix.
Mechanical Properties and Antimicrobial Activity of Silicone Rubber Compounds Containing Acrylated Norfloxacin and Its Polymer
Authors: Yang Hea‐Sun , Park Eun‐Soo 
Published: June 2006

AbstractSummary: Antibacterial silicone rubbers (SR) were prepared by platinum curing and peroxide curing of a silicone compound containing the synthetic antimicrobial monomer 1‐ethyl‐6‐fluoro‐7‐{4‐[2‐hydroxy‐3‐(2‐methylacryloyloxy)‐propyl]piperazin‐1‐yl}‐4‐oxo‐1,4‐dihyroquinoline‐3‐carboxylic acid (MQ) and its polymer PMQ. The effects of the two curing systems on the mechanical properties were compared. Tensile strength and elongation at break of the platinum‐cured SR decreased with increasing concentrations of MQ and PMQ. For the peroxide curing system, the elongation at break increased with increasing concentrations of the antimicrobial agents. The antibacterial activity of the prepared SR was examined by the shake flask test against Staphylococcus aureus and Escherichia coli, which are representative of Gram‐positive and Gram‐negative bacteria, respectively. All compounds showed excellent antibacterial activities against these two types of bacteria.Structure of acrylated norfloxacin.magnified imageStructure of acrylated norfloxacin.
Reinforcement of Elastomer by Starch
Authors: Tang Huaiguo , Qi Qing , Wu Youping , Liang Guihua , Zhang Liqun , Ma Jun 
Published: June 2006

AbstractSummary: Significant reinforcement of styrene‐butadiene‐rubber was achieved by the novel modification of starch through the use of a resorcinol‐formaldehyde and a silane surfactant. The mechanical property improvement by the modified starch is comparable with that reinforced by carbon black. SEM micrograph shows fine morphologies caused by the modification. Dynamic mechanical test shows the advantages of the modified SBR/starch composite: the lowered glass transition temperature means improved low temperature properties; the decreased Tan delta value predicts a smaller internal temperature rise produced by dynamic stress; the increased storage modulus indicates this material is of higher hardness; the improved loss modulus demonstrates higher resistance to tearing.Tensile strength and tear strength of SBR/starch with co‐modification by KH‐792 and RF.magnified imageTensile strength and tear strength of SBR/starch with co‐modification by KH‐792 and RF.
Synthesis, Characterization, and Properties of Multifunctional Epoxy Maleimide Resins
Authors: Mustata Fanica , Bicu Ioan 
Published: June 2006

AbstractSummary: Novel multifunctional formaldehyde resins bearing diaminodiphenylmethane groups are synthesized by the polymerization of a mixture of diaminodiphenylmethane (DDM), o‐cresol (o‐Cz), and cyclohexanone (CHx) with formaldehyde (FA) (at a molar ratio of monomers/formaldehyde, 1/1), in the presence of acid catalyst (HCl). The obtained resins are epoxidated with a large excess of epichlorohydrin and transformed into multifunctional epoxy resins. The multifunctional epoxy maleimide resins are obtained by reaction of the epoxy resins with carboxy phenyl maleimide in the presence of triethylamine as a catalyst. The resultant resins are characterized by IR and NMR spectroscopy, elemental, and thermal analysis. The curing and thermal behavior of these epoxy maleimide resin/DDM systems are investigated using differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques. The activation energies of the curing reactions are situated in the range of 53–90 kJ · mol−1. The cured products have good thermal properties, and activation energies of degradation reactions have values between 42–74 kJ · mol−1.The curing reaction of multifunctional epoxy maleimide resins with DDM.magnified imageThe curing reaction of multifunctional epoxy maleimide resins with DDM.
Anisotropically weighted Poincaré‐type inequalities; Application to the Oseen problem
Authors: Amrouche Chérif , Razafison Ulrich 
Published: June 2006

AbstractThe aim of this article is to prove Poincaré‐type inequalities concerning functions in Sobolev spaces with anisotropic weights that appear in the investigation of the Oseen equations. The inequalities are a generalization and an extension of inequalities we established in a previous work. As an application, we derive existence result and anisotropically weighted Lp estimates for the pressure of the Oseen problem in ℝ3. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On factorization of Schatten class type mappings
Authors: de Andrade Mendes Cristiane 
Published: June 2006

AbstractWe present some results on factorization of multilinear mappings and polynomials of Schatten class type 𝒮2 through infinite dimensional Banach spaces, ℒ︁1 and ℒ︁∞ spaces. We conclude this work with a factorization result for holomorphic mappings of Schatten class type 𝒮2. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flows on few paths: Algorithms and lower bounds
Authors: Martens Maren , Skutella Martin 
Published: June 2006

AbstractThe classical network flow theory allows decomposition of flow into several chunks of arbitrary sizes traveling through the network on different paths. In the first part of this article we consider the unsplittable flow problem where all flow traveling from a source to a destination must be sent on only one path. We prove a lower bound ofΩ(logm/log logm) on the performance of a general class of algorithms for minimizing congestion wheremis the number of edges in a graph. These algorithms start with a solution for the classical multicommodity flow problem, compute a path decomposition, and select one of its paths for each commodity in order to obtain an unsplittable flow. Our result matches the best known upper bound for randomized rounding—an algorithm of this type introduced by Raghavan and Thompson. The k‐splittable flow problem is a generalization of the unsplittable flow problem where the number of paths is bounded for each commodity. We study a new variant of this problem with additional constraints on the amount of flow being sent along each path. We present approximation results for two versions of this problem with the objective to minimize the congestion of the network. The key idea is to reduce the problem under consideration to an unsplittable flow problem while only losing a constant factor in the performance ratio. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 48(2), 68–76 2006
Numerical evaluation of harmonic Green's functions for triclinic half‐space with embedded sources—Part I: a 2D model
Authors: Chen Zhengxiang , Dravinski Marijan 
Published: June 2006

AbstractThe Green's functions for a triclinic half‐space for embedded harmonic line load are considered. Corresponding displacement and stress fields are expressed in terms of double Fourier integrals. The first integral was evaluated using contour integration while the second one was computed through the Gauss–Legendre quadrature. The resulting Green's functions algorithm avoids repeated calculations of the same quantities and utilizes the vector computational features within MATLAB environment. Extensive testing of the results has been performed for both displacement and stress fields. The tests demonstrate the accuracy of the proposed procedure for evaluating the Green's functions without any restrictions upon material properties, frequency, and location of the source and observation points. Copyright © 2006 John Wiley & Sons, Ltd.
Detection of operons
Authors: Yan Yongpan , Moult John 
Published: June 2006

AbstractOperons are clusters of genes that are transcribed as a single message, and regulated by the same gene expression machinery. They are found primarily in prokaryotic genomes. Because genes in the same operon are likely to have related functions, identification of the operon structure is potentially useful for assigning gene function. We report the development and benchmarking of two different methods for detecting operons, based on an analysis of 42 fully sequenced prokaryotic organisms. The Gene Neighbor method (GNM) utilizes the relatively high conservation of gene order in operons, compared with genes in general. The Gene Gap Method (GGM) makes use of the relatively short gap between genes in operons compared with that otherwise found between adjacent genes. The methods have been benchmarked using KEGG pathway data and RegulonDB Escherichia coli operon data. With optimum parameters, the specificity of the GNM is 93% and the sensitivity is 70%. For the GGM, the specificity is 95% and the sensitivity is 68%. Together, the two methods have a sensitivity of 87.2%, while joint predictions have a sensitivity of 50% and a specificity of 98%. The methods are used to infer possible functions for some hypothetical genes in prokaryotic genomes. The methods have proven a useful addition to structure information in deriving protein function in a structural genomics project. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Phosphorylation‐induced transient intrinsic structure in the kinase‐inducible domain of CREB facilitates its recognition by the KIX domain of CBP
Authors: Solt Iván , Magyar Csaba , Simon István , Tompa Peter , Fuxreiter Monika 
Published: June 2006

AbstractPhosphorylation at Ser‐133 of the kinase inducible domain of CREB (KID) triggers its binding to the KIX domain of CBP via a concomitant coil‐to‐helix transition. The exact role of this key event is still puzzling: it does not switch between disordered and ordered states, nor its direct interactions fully account for selectivity. Hence, we reasoned that phosphorylation may shift the conformational preferences of KID towards a binding‐competent state. To this end we investigated the intrinsic structural properties of the unbound KID in phosphorylated and unphosphorylated forms by simulated annealing and molecular dynamics simulations. Although helical populations show subtle differences, phosphorylation reduces the flexibility of the turn segment connecting the two helices in the complexed structure and induces a transient structural element that corresponds to its bound conformation. It is stabilized by the pSer‐133–Arg‐131 interaction, which is absent from the unphosphorylated KID. Diminishing this coupling decreases the 3.1 kcal/mol contribution of pSer‐133 to the binding free energy (ΔGbind) of the phosphorylated KID to KIX by 1.1 kcal/mol, as computed in reference to Ser‐133. In a binding competent form of the S133E KID mutant, the contribution of Glu‐133 to ΔGbind is by 1.5 kcal/mol smaller than that of pSer, suggesting that altered structural properties due to pSer → Glu replacement impair the binding affinity. Thus, we propose that phoshorylation contributes to selectivity not merely by the direct interactions of the phosphate group with KIX, but also by promoting the formation of a transient structural element in the highly conserved turn segment. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Some remarks on the calculation of the complex refractive index of medium in terahertz reflection spectroscopy
Authors: Gornov Evgeny , Peiponen Kai‐Erik 
Published: June 2006

AbstractThis paper presents a technique, based on dispersion theory, for the analysis of terahertz reflection spectroscopy data measured using ellipsometric methods. Formulas for the complex reflection coefficient provide simpler equations than those used in conventional ellipsometry for resolving the complex refractive index in the THz spectral range. It is proposed that a reflection coefficient ratio yields information on the surface roughness when probing a surface by THz radiation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
octopus:a tool for the application of time‐dependent density functional theory
Authors: Castro Alberto , Appel Heiko , Oliveira Micael , Rozzi Carlo A. , Andrade Xavier , Lorenzen Florian , Marques M. A. L. , Gross E. K. U. , Rubio Angel 
Published: June 2006

AbstractWe report on the background, current status, and current lines of development of theoctopusproject. This program materializes the main equations of density‐functional theory in the ground state, and of time‐dependent density‐functional theory for dynamical effects. The focus is nowadays placed on the optical (i.e. electronic) linear response properties of nanostructures and biomolecules, and on the non‐linear response to high‐intensity fields of finite systems, with particular attention to the coupled ionic‐electronic motion (i.e. photo‐chemical processes). In addition, we are currently extending the code to the treatment of periodic systems (both to one‐dimensional chains, two‐dimensional slabs, or fully periodic solids), magnetic properties (ground state properties and excitations), and to the field of quantum‐mechanical transport or “molecular electronics.” In this communication, we concentrate on the development of the methodology: we review the essential numerical schemes used in the code, and report on the most recent implementations, with special attention to the introduction of adaptive coordinates, to the extension of our real‐space technique to tackle periodic systems, and on large‐scale parallelization. More information on the code, as well as the code itself, can be found athttp://www.tddft.org/programs/octopus/. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)