bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphonium‐modified layered silicate epoxy resins nanocomposites and their combinations with ATH and organo‐phosphorus fire retardants
Authors: Schartel Bernhard , Knoll Uta , Hartwig Andreas , Pütz Dirk 
Published: March 2006

AbstractPhosphonium‐modified layered silicate epoxy resin nanocomposites were evaluated by testing the thermal/thermo‐mechanical properties [differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), torsional pendulum, Sharpy toughness], flammability (limiting oxygen index LOI) and fire behavior (cone calorimeter with different irradiations). The morphology of the composites was determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The drying conditions of phosphonium‐modified layered silicate were varied in order to improve the nanocomposite formation and properties. The results were compared with using a commercial ammonium‐modified montmorillonite. Enhanced nanocomposite formation was found for the commercial systems due to the amount of excess surfactant, but this effect was overcompensated through the advanced morphology of the phosphonium‐modified systems. Several fire retardancy mechanisms and their specific influence on the different fire properties, such as ignitability, flammability, flame spread, total heat release (fire load), and the production of CO and smoke were discussed comprehensively. The main mechanism of layered silicate is a barrier formation influencing the flame spread in developing fires. Several minor mechanisms are significant, but important fire properties such as flammability or fire load are hardly influenced. Hence combinations with aluminum hydroxide and organo‐phosphorus flame retardants were evaluated. The combination with aluminum hydroxide was a promising approach since it shows superposition in properties such as the fire load and only in some properties very little antagonism. The combination with an organo‐phosphorus flame retardant disillusions, since it was characterized mainly by antagonism. Copyright © 2006 John Wiley & Sons, Ltd.
Survivin: An inhibitor of apoptosis in pediatric cancer
Authors: Fangusaro Jason R. , Caldas Hugo , Jiang Yuying , Altura Rachel A. 
Published: March 2006

AbstractSurvivin is an inhibitor of apoptosis protein (IAP) expressed in a large number of adult malignancies. Its expression levels correlate with more aggressive disease and poor clinical outcome in many of these tumors. As its expression is restricted in normal adult differentiated tissues, it has become of great interest as both a tumor prognostic marker and as a potential biologic target for future anti‐cancer therapies. Survivin expression and Survivin‐based therapies have been examined in many of the more common pediatric malignancies. We present an overview of Survivin function and current research exploring its biologic and therapeutic roles in pediatric tumors. Pediatr Blood Cancer © 2006 Wiley‐Liss, Inc.
Surface‐initiated nitroxide‐mediated polymerization: a tool for hybrid inorganic/organic nanocomposites ‘in situ’ synthesis
Authors: Ghannam Leïla , Parvole Julien , Laruelle Gael , Francois Jeanne , Billon Laurent 
Published: March 2006

AbstractHybrid silica particles comprised of an inorganic core and an organic polymer shell can be synthesized by surface‐initiated nitroxide‐mediated polymerization (SINMP) in the presence of a grafted alkoxyamine as initiator. The layer of initiator molecules attached or adsorbed to the particles surface is based on a nitroxide group. The synthesis and characterization of these alkoxyamine structures are briefly described. The grafted initiator particles are studied in order to determine the nature of the anchorage sites and the grafting density. With a stable radical or nitroxide as chain‐growth moderator tethered to the inorganic core, it was demonstrated that the grafting from or to SINMP exhibits a control character with a very low polydispersity and good agreement between theoretical/experimental molecular weights. A comparative review of different alkoxyamines with a bimolecular system based on a grafted azoic initiator in the presence of an acyclic β‐phosphonylated nitroxide called SG1 is also described. Moreover, original methods for the synthesis of alkoxyamine grafted surface by in situ trapping of carbon radicals and some new developments for colored pigments will be reported. These topics could be one of the directions of the field in the next years. Copyright © 2006 Society of Chemical Industry
Modification of Nafion membrane using poly(4‐vinyl pyridine) for direct methanol fuel cell
Authors: Woong Jeon Chan , Venkataramani Sriram , Kim Sung Chul 
Published: March 2006

AbstractPerfluorinated membrane such as Nafion (from Du‐Pont) has been used as a polymer electrolyte membrane. Nafion 117 membrane, which was usually used as the electrolyte membrane for the polymer electrolyte membrane fuel cell (PEMFC), was modified by using poly(4‐vinyl pyridine) (P4VP) to reduce the methanol crossover, which cause fuel losses and lower power efficiency, by the formation of an ionic crosslink structure (sulfonic acid‐pyridine complex) on the Nafion 117 surface. Nafion film was immersed in P4VP/N‐methyl pyrrolidone (NMP) solution. P4VP weight percent of modified membrane was controlled by changing the concentration of P4VP/NMP solution and the dipping time. P4VP weight percent increased with increasing concentration of dipping solution and dipping time. The thickness of the P4VP layer increased with increasing concentration of dipping solution and dipping time when the concentration of the dipping solution was low. At high P4VP concentration, the thickness of the P4VP layer was almost constant owing to the formation of acid–base complex which interrupted the penetration of P4VP. FTIR results showed that P4VP could penetrate up to 30 µm of Nafion 117 membrane. Proton conductivity and methanol permeability of modified membrane were lower than those of Nafion 117. Both decreased with increasing concentration of dipping solution and dipping time. Methanol permeability was observed to be more dependent on the penetration depth of P4VP. Water uptake of the modified membrane, the important factor in a fuel cell, was lower than that of Nafion 117. Water uptake also decreased with increasing of P4VP weight. On the basis of this study, the thinner the P4VP layer on the Nafion 117 membrane, the higher was the proton conductivity. Methanol permeability decreased exponentially as a function of P4VP weight percent. Copyright © 2006 Society of Chemical Industry
Highly magnetic latexes from submicrometer oil in water ferrofluid emulsions
Authors: Montagne Franck , Mondain‐Monval Olivier , Pichot Christian , Elaïssari Abdelhamid 
Published: March 2006

AbstractThe synthesis of functionalized submicrometer magnetic latex particles is described as obtained from a preformed magnetic emulsion composed of organic ferrofluid droplets dispersed in water. Composite (polystyrene/γ‐Fe2O3) particles were prepared according to a two‐step procedure including the swelling of ferrofluid droplets with styrene and a crosslinking agent (divinyl benzene) followed by seeded emulsion polymerization with either an oil‐soluble [2,2′‐azobis(2‐isobutyronitrile)] or water‐soluble (potassium persulfate) initiator. Depending on the polymerization conditions, various particle morphologies were obtained, ranging from asymmetric structures, for which the polymer phase was separated from the inorganic magnetic phase, to regular core–shell morphologies showing a homogeneous encapsulation of the magnetic pigment by a crosslinked polymeric shell. The magnetic latexes were extensively characterized to determine their colloidal and magnetic properties. The desired core–shell structure was efficiently achieved with a given styrene/divinyl benzene ratio, potassium persulfate as the initiator, and an amphiphilic functional copolymer as the ferrofluid droplet stabilizer. Under these conditions, ferrofluid droplets were successfully turned into superparamagnetic polystyrene latex particles, about 200 nm in size, containing a large amount of iron oxide (60 wt %) and bearing carboxylic surface charges. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2642–2656, 2006
DFT calculations of the ionization potentials and electron affinities of serinamide
Authors: Lu Jinfeng , Zhu Songling , Zhou Zhengyu , Wu Qunyan , Zhao Gang 
Published: March 2006

AbstractAdiabatic and vertical ionization potentials (IPs) and valence electron affinities (EAs) of serinamide in the gas phase have been determined using density functional theory (DFT) B3LYP, B3P86, and B3PW91 methods with the 6‐311++G** and 6‐311G** basis sets, respectively. IPs and EAs of serinamide in solution have been calculated with the B3LYP method using the 6‐311++G** and 6‐311G** basis sets. Eight possible conformers of serinamide and its charged states in the gas phase have been optimized employing the DFT B3LYP method with 6‐311++G** and 6‐311G** basis sets, respectively. All the adiabatic and vertical ionization potentials (AIPs and VIPs) of eight serinamide conformers in our work are positive values, whether in the gas phase or in solutions; the IPs in solutions are smaller than the results in the gas phase and decrease with increased dielectric constants in solutions. This finding indicates that the cationic states in solutions are more stable than those in the gas phase. All EAs of eight serinamide conformers are negative values in the gas phase, indicating that the anionic states are unstable with respect to electron autodetachment, both adiabatically and vertically. In contrast, all other adiabatic electron affinities (AEAs) are negative values in solutions except for 6S in water; 7S in chloroform, acetone, and water; and 8S in acetone and water, and increase with increasing of dielectric constants in solutions. All vertical electron affinities (VEAs) are negative values in solutions; however, no good rule has been found for these values in solutions. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Theoretical study of the reaction mechanism of proton transfer in glycinamide
Authors: Zhang Liqun , Zhou Zhengyu , Du Dongmei , Yuan Pei 
Published: March 2006

AbstractTo investigate the tautomerism of glycinamide that is induced by proton transfer, we present detailed theoretical studies on the reaction mechanism of both the isolated gas phase and H2O‐assisted proton transfer process of glycinamide, using density functional theory calculations by means of the B3LYP hybrid functional. Twenty‐six geometries, including 10 significant transition states, were optimized, and these geometrical parameters are discussed in detail. The relative order of the activation energy for hydrogen atom transfer of all the conformers has been systematically explored in this essay. For the amido hydrogen atom transfer process, the relative order of the activation energy is: IV < II < III < I, while in the carbonic hydrogen atom transfer process, the relative order is IV > II > III > I. Meanwhile, the most favorable structure for both the amido hydrogen atom transfer and the carbonic hydrogen atom transfer has been found. The involvement of the water molecule not only can stabilize the transition states and the ground states, but can also reduce the activation energy greatly. The superior catalytic effect of H2O has been discussed in detail. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Evaluation of DFT methods for computing the interaction energies of homomolecular and heteromolecular dimers of monosubstituted benzene
Authors: Godfrey‐Kittle Andrew , Cafiero Mauricio 
Published: March 2006

AbstractWe present density functional theory (DFT) interaction energies for the sandwich and T‐shaped conformers of substituted benzene dimers. The DFT functionals studied include TPSS, HCTH407, B3LYP, and X3LYP. We also include Hartree–Fock (HF) and second‐order Møller–Plesset perturbation theory calculations (MP2), as well as calculations using a new functional, P3LYP, which includes PBE and HF exchange and LYP correlation. Although DFT methods do not explicitly account for the dispersion interactions important in the benzene–dimer interactions, we find that our new method, P3LYP, as well as HCTH407 and TPSS, match MP2 and CCSD(T) calculations much better than the hybrid methods B3LYP and X3LYP methods do. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Kinetics and structural aspects of the cisplatin interactions with guanine: A quantum mechanical description
Authors: Costa Luiz Antônio S. , Hambley Trevor W. , Rocha Willian R. , De Almeida Wagner B. , Dos Santos Hélio F. 
Published: March 2006

AbstractThe interaction of cisplatin with guanine DNA bases has been investigated using ab initio Hartree–Fock (HF) and density functional levels of theory in gas phase and aqueous solution. The overall process was divided into three steps: the reaction of the monoaqua [Pt(NH3)2Cl(H2O)]+ species with guanine (G) (reaction 1), the hydrolysis process yielding the adduct [Pt(NH3)2(G) (H2O)]2+ (reaction 2) and the reaction with a second guanine leading to the product [Pt(NH3)2(G)2]2+ (reaction 3). The functionals B3LYP, BHandH, and mPW1PW91 were used in the present study, to develop an understanding of the role of the distinct models. The geometries presented for the intermediate structures were obtained by IRC calculations from the transition state structure for each reaction. The structural analysis for the intermediates and transition states showed that hydrogen bonds with the guanine O6 atom play an important role in stabilizing these species. The geometries were not very sensitive to the level of theory applied with the HF level, giving a satisfactory overall performance. However, the energy barriers and the rate constants were found to be strongly dependent on the level of calculation and basis set, with the DFT calculations giving more accurate results. For reaction 1 the rate constant calculated in aqueous solution at PCM‐BHandH/6‐311G* (k1 = 7.55 × 10−1 M−1 s−1) was in good agreement with the experiment (5.4 × 10−1 M−1 s−1). The BHandH/6‐31G* calculated gas phase rate constants for reactions 2 and 3 were: k2 = 0.9 × 10−6 M−1 s−1 and k3 = 2.99 × 10−4 M−1 s−1 in fairly good accordance with the experimental findings for reaction 2 (1.0 × 10−6 M−1 s−1) and reaction 3 (3.0 × 10−4 M−1 s−1). © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Restricted and unrestricted Hartree–Fock approaches applied to spherical quantum dots in a magnetic field
Authors: Destefani C. F. , Vianna J. D. M. , Marques G. E. 
Published: March 2006

AbstractThe Roothaan and Pople–Nesbet approaches for real atoms are adapted to quantum dots in the presence of a magnetic field. Single‐particle Gaussian basis sets are constructed, for each dot radius, under the condition of maximum overlap with the exact functions. The chemical potential, charging energy, and total spin expected values are calculated, and we have verified the validity of the quantum dot energy shell structure as well as Hund's rule for electronic occupation at zero magnetic field. At finite field, we have observed the violation of Hund's rule and studied the influence of magnetic field on the closed and open energy shell configurations. We have also compared the present results with those obtained within the LS‐coupling scheme for low electronic occupation numbers. We focus only on ground‐state properties and consider quantum dots populated up to 40 electrons, constructed by GaAs or InSb nanocrystals. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
An improved non‐sequential multi‐input multi‐output quantitative feedback theory design methodology
Authors: L. Kerr Murray , Jayasuriya Suhada 
Published: March 2006

AbstractThis paper presents an improved non‐sequential multi‐input multi‐output (MIMO) Quantitative Feedback Theory (QFT) design methodology for uncertain systems. A non‐sequential MIMO QFT stability theorem is derived that serves as the basis for an improvement of the design methodology, whereby it can be successfully applied to non‐minimum phase systems, albeit with a degree of conservatism partially inherent in independent and decentralized design methodologies. The results reduce the conservatism in a non‐sequential MIMO QFT design and provide insight into the plant cases for which the methodology can be successfully applied. Copyright © 2006 John Wiley & Sons, Ltd.
Physiographic characteristics of bridge‐stream intersections
Authors: Johnson Peggy A. 
Published: March 2006

AbstractBridges that cross streams can be greatly affected by channel instabilities, such as channel widening, lateral migration and channel bed degradation. Attention to channel conditions in the vicinity of bridges is an important aspect of bridge maintenance and safety. Channel stability is also critical to goals of multi‐objective river management. Given that channel stability is important for both river management and the structural stability of bridges, any river management scheme should consider the stability of bridge‐stream intersections. In this paper, the characteristics of bridge‐stream intersections across the United States are described based on existing literature and recent field observations. A set of recommendations for addressing and improving channel stability at bridges is suggested, including: (1) controlling water and sediment discharges at the catchment level; (2) revegetating channel banks with woody vegetation; (3) reshaping the channel cross‐section to a more stable, configuration; (4) removing disturbances from the stream channel, such as cattle and (5) using structures to control flow near channel beds and banks. The physiographic setting is a factor in the solution of at least the first three suggestions in this list. Attention to the physical characteristics of bridge‐stream intersections in the various physiographic regions can lead to sustainable solutions for stabilizing channels at bridge‐stream intersections. Copyright © 2006 John Wiley & Sons, Ltd.
Some aspects of the reproductive biology of two Atlantic species of Polycera (Mollusca: Opisthobranchia)
Authors: Martínez-Pita Ines , Sánchez-España Ana I. , García Francisco J. 
Published: March 2006

Spawn and the embryonic development of two species of the genus Polycera were studied. Both species, Polycera aurantiomarginata and Polycera quadrilineata, were collected in the intertidal zone of El Portil (Huelva) in south-western Spain. In the laboratory spawn were collected daily. Length and width of the spawn, number of eggs per mm2, egg size and capsule size were measured. The egg masses were controlled several times a day to provide a timetable for the main developmental events until hatching. Embryonic growth was measured between some characteristic stages (gastrula, preveliger, primordial velum and veliger prior to hatch).The two species differ in a number of aspects: spawn are longer, eggs and capsules are bigger in P. aurantiomarginata than in P. quadrilineata. The number of eggs per mm2, however, is greater in P. quadrilineata than in its congener. Furthermore, spawn of P. quadrilineata are semicircular whereas those of P. aurantiomarginata are spiral and wavy. Both species show planktotrophic development but embryonic development of P. quadrilineata is faster than that of P. aurantiomarginata. The dynamic of embryonic growth is very similar in the two species, although embryos of P. aurantiomarginata are larger at any measured stage than those of P. quadrilineata.
Regulation of IL‐1‐induced selective IL‐6 release from human mast cells and inhibition by quercetin
Authors: Kandere‐Grzybowska Kristiana , Kempuraj Duraisamy , Cao Jing , Cetrulo Curtis L , Theoharides Theoharis C 
Published: March 2006

Mast cells are involved in allergic reactions, but also in innate immunity and inflammation. Crosslinkage of mast cell Fc immunoglobulin E receptors (FcɛRI) by multivalent antigen triggers secretion of granule‐stored mediators, as well asde novosynthesis of cytokines, including interleukin (IL)‐6.We showed recently that the proinflammatory cytokine IL‐1 stimulates human leukemic mast cells (HMC‐1) and human umbilical cord blood‐derived cultured mast cells (hCBMCs) to release newly synthesized IL‐6 without tryptase in the absence of degranulation.Here, we investigated several signal‐transduction pathways activated by IL‐1 leading to IL‐6 production by HMC‐1 and hCBMCs.We also investigated the effect of the flavonol quercetin that was recently shown to strongly inhibit IL‐6 secretion in response to allergic stimulation from hCBMCs.IL‐1 stimulated p38, but did not activate extracellular signal‐regulated kinase (ERK) or c‐jun N‐terminal kinase (JNK); it also did not activate protein kinase C (PKC) isozymesα,β,μandζ, except for PKC‐θ, which was phosphorylated.The p38 inhibitor SB203580 and the PKC inhibitors Calphostin C and Gö6976 completely inhibited IL‐1‐induced IL‐6 production.Quercetin 1–100 μMinhibited IL‐1‐induced IL‐6 secretion, p38 and PKC‐θphosphorylation in a dose‐dependent manner.These results indicate that IL‐1‐stimulated IL‐6 production from human mast cells is regulated by biochemical pathways distinct from IgE‐induced degranulation and that quercetin can block both IL‐6 secretion and two key signal transduction steps involved.British Journal of Pharmacology(2006)148, 208–215. doi:10.1038/sj.bjp.0706695
An Outbreak of Community-Onset Methicillin-ResistantStaphylococcus aureusSkin Infections in Southwestern Alaska
Authors: Baggett Henry C. , Hennessy Thomas W. , Leman Richard , Hamlin Cindy , Bruden Dana , Reasonover Alisa , Martinez Patricia , Butler Jay C. 
Published: March 2006

AbstractObjective:We investigated a large outbreak of community-onset methicillin-resistantStaphylococcus aureus(MRSA) infections in southwestern Alaska to determine the extent of these infections and whether MRSA isolates were likely community acquired.Design:Retrospective cohort study.Setting:Rural southwestern Alaska.Patients:All patients with a history of culture-confirmed S.aureusinfection from March 1, 1999, through August 10, 2000.Results:More than 80% of culture-confirmed S.aureusinfections were methicillin resistant, and 84% of MRSA infections involved skin or soft tissue; invasive disease was rare. Most (77%) of the patients with MRSA skin infections had communityacquired MRSA (no hospitalization, surgery, dialysis, indwelling line or catheter, or admission to a long-term-care facility in the 12 months before infection). Patients with MRSA skin infections were more likely to have received a prescription for an antimicrobial agent in the 180 days before infection than were patients with methicillin-susceptible S.aureusskin infections.Conclusions:Our findings indicate that the epidemiology of MRSA in rural southwestern Alaska has changed and suggest that the emergence of community-onset MRSA in this region was not related to spread of a hospital organism. Treatment guidelines were developed recommending that beta-lactam antimicrobial agents not be used as a first-line therapy for suspectedS. aureusinfections.