bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of PU/PMMA hybrid particles from miniemulsion polymerization: Thermodynamic considerations
Authors: Li Chien‐Yu , Chiu Wen‐Yen , Don Trong‐Ming 
Published: June 2007

AbstractThe morphology of PU/PMMA hybrid particles prepared by miniemulsion polymerization was predicted through the consideration of their Gibbs free energy changes. Five morphological states of PU/PMMA hybrid particles were proposed and their Gibbs free energy changes were calculated. Before the formation of hybrid particles, the initial state included a monomer mixture of PU prepolymer, MMA, a chain extender, TMP, and an initiator, which was in droplets suspended in water containing SDS. Two assumptions were made. First, the densities of all states were the same. Secondly, secondary nucleation of particles was negligible. Thus the size of initial droplet and final particle was unchanged through miniemulsion polymerization. The interfacial tensions were measured by a pendant drop method and were used for calculation. The preferred morphology of PU/PMMA hybrid particle had the minimum value of ΔGphase. Different NCO/OH ratios of PU and initiators of MMA were used to study the morphological change of PU/PMMA hybrid particles. When BD was used as the chain extender of PU, the hybrid particles showed the PU‐rich phase as the shell and PMMA‐rich as the core. When incorporating bisphenol A into PU polymer, the homogeneous structure of hybrid particle was preferred. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3359–3369, 2007
Model reaction for thermally latent curing through addition of hemiacetal ester and epoxide by schiff‐base–zinc halide complexes
Authors: Komatsu Hiroyuki , Ochiai Bungo , Hino Tetsuo , Endo Takeshi 
Published: June 2007

AbstractSchiff‐base–zinc halide complexes (ZnX2/1) thermal‐latently catalyze the reaction of glycidyl phenyl ether (2) and 1‐propoxyethyl 2‐ethylhexanoate (3) that proceeds at moderately elevated temperatures. The catalysis by the ZnX2/1 complexes proceeds via the thermal dissociation of 3 to produce the corresponding carboxylic acid that nucleophilically attacks 2 predominantly over the thermally dissociated vinyl ether. ZnX2/1 complexes catalyze both the dissociation of 3 to produce the carboxylic acid intermediate and its addition to 2. Although conventional latent catalysts for this reaction exhibit Lewis acidities under ambient conditions that are responsible to the gradual degradation of hemiacetal esters and the polymerization of epoxides, a mixture of 2, 3, and ZnX2/1 can be stored for 3 months at ambient conditions. The stored mixture is as active as the freshly prepared mixture, keeping the excellent activity and latency of ZnX2/1. As well as the model reaction, the thermally latent polyaddition of bisphenol A diglycidyl ether (9) and di‐1‐propoxyethyl adipate (10) is also promoted with ZnCl2/1 at a moderate elevated temperature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3370–3379, 2007
Synthesis and properties of polyurethanes bearing urethane moieties in the side chain
Authors: Ochiai Bungo , Sato Shin‐Ich , Endo Takeshi 
Published: June 2007

AbstractPolyurethanes bearing urethane groups in the side chains were prepared by the addition of isocyanates to the hydroxyl groups in poly(hydroxyurethane) prepared by the polyaddition of a bifunctional cyclic carbonate with 1,12‐diaminododecane. The urethanization proceeded quantitatively in the presence of a catalytic amount of di‐n‐butyltin dilaurate. The resulting polyurethane had a higher glass transition temperature than the original poly(hydroxyurethane), although its esterified product had a lower glass transition temperature. The urethanization with 3‐(triethoxysilyl)propyl isocyanate also proceeded effectively to afford both soluble and insoluble polymers, depending on the reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3408–3414, 2007
Highly active ethylene polymerization and copolymerization with norbornene using bis(imino‐indolide) titanium dichloride–MAO system
Authors: Zuo Weiwei , Sun Wen‐Hua , Zhang Shu , Hao Peng , Shiga Akinobu 
Published: June 2007

AbstractA catalytic system of new titanium complexes with methylaluminoxane (MAO) was found to effectively polymerize ethylene for high molecular weight polyethylene as well as highly active copolymerization of ethylene and norbornene. The bis (imino‐indolide)titanium dichlorides (L2TiCl2, 1–5), were prepared by the reaction of N‐((3‐chloro‐1H‐indol‐2‐yl)methylene)benzenamines with TiCl4, and characterized by elemental analysis, 1H and 13C NMR spectroscopy. The solid‐state structures of 1 and 4 were determined by X‐ray diffraction analysis to reveal the six‐coordinated distorted octahedral geometry around the titanium atom with a pair of chlorides and ligands in cis‐forms. Upon activation by MAO, the complexes showed high activity for homopolymerization of ethylene and copolymerization of ethylene and norbornene. A positive “comonomer effect” was observed for copolymerization of ethylene and norbornene. Both experimental observations and paired interaction orbital (PIO) calculations indicated that the titanium complexes with electron‐withdrawing groups in ligands performed higher catalytic activities than those possessing electron‐donating groups. Relying on different complexes and reaction conditions, the resultant polyethylenes had the molecular weights Mw in the range of 200–2800 kg/mol. The influences on both catalytic activity and polyethylene molecular weights have been carefully checked with the nature of complexes and reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3415–3430, 2007
A novel and facile preparation method of hollow silica spheres containing small SiO2 cores
Authors: Cheng Xinjian , Chen Min , Wu Limin , You Bo 
Published: June 2007

AbstractThis article presents a novel and facile preparation method of hollow silica spheres with loading small silica inside. In this approach, positively charged SiO2/polystyrene core‐shell composite particles were synthesized first, when the silica shells from the sol‐gel process of tetraethoxysilane were then coated on the surfaces of composite particles via electrostatic interaction, the polystyrene was dissolved subsequently even synchronously in the same medium to form hollow silica spheres with small silica cores. TEM, SEM, and FTIR measurements were used to characterize these composite spheres. Based on this study, some inorganic or organic compounds could be loaded into these hollow silica spheres. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3431–3439, 2007
Synthesis and opto‐electrical properties of dendron‐containing poly(2,3‐diphenyl‐1,4‐phenylenevinylene) derivatives
Authors: Yang Sheng‐Hsiung , Chen Shiang‐Ying , Wu Yu‐Chun , Hsu Chain‐Shu 
Published: June 2007

AbstractA new series of poly(2,3‐diphenyl‐1,4‐phenylenevinylene) derivatives containing dendritic side groups were synthesized. Different generations of dendrons were integrated on the pendant phenyl ring to investigate their effect on optical and electrical properties of final polymers. Homopolymers can not be obtained via the Gilch polymerization because of sterically bulky dendrons. By controlling the feed ratio of different monomers during polymerization, dendron‐containing copolymers with high molecular weights were obtained. The UV–vis absorption and photoluminescent spectra of the thin films are pretty close; however, quantum efficiency is significantly enhanced with increasing the generation of dendrons. The electrochemical analysis reveals that hole‐injection is also improved by increasing dendritic generation. Double‐layer light‐emitting devices with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al were fabricated. High generation dendrons bring benefit of improved device performance. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3440–3450, 2007
Calorimetry in nonstandard conditions: The noncrystalline phases of linear polyethylene
Authors: Jedidi Ilyes , Ferhat‐Hamida Zohra , Delmas Geneviève 
Published: June 2007

AbstractA linear Union Carbide PE (UC) has been analyzed by nonstandard calorimetry with a common DSC calorimeter and a Setaram C80 calorimeter. Nonstandard calorimetry entails using a low rate of heating (0.5–1 K/min), a small mass (0.5–1.5 mg), and an open cell (O‐cell) instead of the standard C‐cell. Events in O‐cells overlap less and occur with a faster kinetics than in C‐cells. PE crystals are nascent, solution‐grown (S‐grown), press‐grown (P‐grown), and strained by extrusion. In Part A, the traces show that the phase‐changes in the melt, previously observed in a C80 calorimeter (slow T‐ramp) and characterized by ΔHnetwork, can be observed with a common DSC in nonstandard conditions. In Part B, the difference between the C‐ and O‐cells and the changes in the main peak enthalpy (ΔHortho) are of interest. The main result is that, in O‐cells, the value of ΔHortho around Tortho, exceeds unambiguously in certain conditions ΔHortho found for perfect orthorhombic crystals. The main endotherm contains then another contribution, namely ΔHnetwork. Crystal reorganization during the slow T‐ramp is followed in the C‐ and O‐cells on S‐grown crystals. In O‐cells, lamellar thickening observed in the slow‐ramp is more extensive. The ease of phase‐change depends on the sample history. It is as follows: strained‐part extruded > nascent > S‐grown > P‐grown. Co‐operative chain motions are more hindered in the standard C‐cells than in the O‐cells. In Part C, lower values of m succeed in bringing phase‐changes in P‐grown (O‐cells) samples. The origin of the events is discussed: three processes are thought to contribute to the phase‐changes namely, melting of strained short‐range order, activation of vibrations in the CH2 groups, and fast decay of chain orientation which occurs simultaneously with melting. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1932–1949, 2007
Surface‐treated and multilayered poly(ε‐caprolactone) nanofiber webs exhibiting enhanced hydrophilicity
Authors: Kim Geunhyung , Park Jongha , Park Sua 
Published: June 2007

AbstractTo improve the hydrophilic properties of poly(ε‐caprolactone) (PCL) nano/microfiber webs for tissue engineering scaffolds, PCL webs of various structures were fabricated by electrospinning with single or double nozzles connected to an auxiliary electrode. Surface‐modified and layered PCL fiber webs were made by including water‐soluble poly(ethylene oxide) (PEO) in the PCL electrospinning solution (single‐nozzle method) or by electrospinning of alternating PCL and PEO solutions using two nozzles (double‐nozzle method), respectively. When the PEO component within the resulting webs was removed by dissolution with distilled water, the remnant PCL webs exhibited two distinct structures. Those made by the single‐nozzle method consisted of nanofibers with high surface roughness, whereas those made by the double‐nozzle method consisted of stacked layers of PCL nanofibers. Both types of structured PCL web showed improved hydrophilicity characteristics compared with those of nanofiber webs generated from a pure PCL solution using a typical electrospinning process. Cell culturing and scanning electron microscopy showed that the interactions between human dermal fibroblasts and the structured PCL scaffolds were very favorable. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2038–2045, 2007
Uptake and translocation of non‐ionised pesticides in the emergent aquatic plant parrot feather Myriophyllum aquaticum
Authors: de Carvalho Renato F , Bromilow Richard H , Greenwood Richard 
Published: June 2007

AbstractThe uptake of four 14C‐labelled non‐ionised compounds, the methyl carbamoyloxime insecticide/nematicide oxamyl and three model phenylureas, from solution by rooted stems of the aquatic plant parrot feather [Myriophyllum aquaticum (Vell.) Verdc], together with translocation to the emergent shoots, was measured over periods of 24 and 48 h. Uptake into the submerged tissues of roots and stem base could be ascribed to two processes: movement into the aqueous phase of cells and then partitioning onto the plant solids. This latter process was related to lipophilicity (as measured by the l‐octanol/water partition coefficient, Kow) and gave rise to high uptake rates of the most lipophilic compounds. Translocation to shoots was passive and was optimal at log Kow ∼ 1.8, at which the efficiency of translocation of compound was about 40% of that of water. This optimum log Kow was identical to that observed previously in barley, although the translocation efficiency was somewhat less in parrot feather. Solvation parameters were applied to model uptake and translocation of a set of ten compounds by barley with the particular objective of understanding why translocation efficiency is lower at log Kow > 1.8. Copyright © 2007 Society of Chemical Industry
Insecticide resistance status of Myzus persicae (Hemiptera: Aphididae) populations from peach and tobacco in mainland Greece
Authors: Margaritopoulos John T , Skouras Panagiotis J , Nikolaidou Parthena , Manolikaki Joanna , Maritsa Katherine , Tsamandani Kiveli , Kanavaki Olympia M , Bacandritsos Nikolaos , Zarpas Kostas D , Tsitsipis John A 
Published: June 2007

AbstractThe susceptibility of 88 and 38 field samples of Myzus persicae (Sulzer) to imidacloprid and deltamethrin respectively was examined using the FAO dip test bioassay. The field samples were collected from tobacco and peach from various regions of Greece in the period from 2004 to 2006. In addition, 497, 349 and 370 clones originating from peach and tobacco were screened for the three known resistance mechanisms, elevated esterases, modified acetylcholinesterase (MACE) and knockdown resistance (kdr) respectively, using biochemical and DNA diagnostics. Most of the samples assayed with imidacloprid showed low resistance factors (RFs)–39% below 5 and 21% between 5 and 10. However, 9% of the samples (all from tobacco) showed relatively high RF values (24–73). Differences were found between crops, with higher RF values recorded in samples from tobacco than in those from peach. Bioassays with deltamethrin revealed the development of strong resistance in the populations examined. The RFs were mostly higher than 23, and in 29% of the samples they were extremely high (152–436). Finally, the three known resistance mechanisms were found in high frequencies in the populations examined, although some differences between crops and years were detected. The implications of the study for management schemes against M. persicae are discussed. Copyright © 2007 Society of Chemical Industry
The multipartite system that mediates entry of herpes simplex virus into the cell
Authors: Campadelli‐Fiume Gabriella , Amasio Michele , Avitabile Elisa , Cerretani Arianna , Forghieri Cristina , Gianni Tatiana , Menotti Laura 
Published: June 2007

AbstractThe multipartite entry‐fusion system of herpes simplex virus is made of a quartet of glycoproteins—gD, gB, gH·gL—and three alternative gD receptors, herpesvirus entry mediator (HVEM), nectin1 and modified sites on heparan sulphate. This multipartite system recapitulates the basic steps of virus—cell fusion, i.e. receptor recognition, triggering of fusion and fusion execution. Specifically, in addition to serving as the receptor‐binding glycoprotein, gD triggers fusion through a specialised domain, named pro‐fusion domain (PFD), located C‐terminally in the ectodomain. In the unliganded gD the C‐terminal region folds around the N‐terminal region, such that gD adopts a closed autoinhibited conformation. In HVEM‐ and nectin1‐bound gD the C‐terminal region is displaced (opened conformation). gD is the tool for modification of HSV tropism, through insertion of ligands to heterologous tumour‐specific receptors. It is discussed whether gD responds to the interaction with the natural and the heterologous receptors by adopting similar conformations, and whether the closed‐to‐open switch in conformation is a generalised mechanism of activation. A peculiar recombinant highlighted that the central Ig‐folded core of gD may not encode executable functions for entry and that the 219–314 aa segment may be sufficient to trigger fusion. With respect to fusion execution, gB appears to be a prospective fusogen based on its coiled‐coil trimeric structure, similar to that of another fusion glycoprotein. On the other hand, gH exhibits molecular elements typical of class 1 fusion glycoproteins, in particular heptad repeats and strong tendency to interact with lipids. Whether fusion execution is carried out by gB or gH·gL, or both glycoproteins in complex or sequentially remains to be determined. Copyright © 2007 John Wiley & Sons, Ltd.
Passage of non‐salmonid fish through a Deelder lock on a lowland river
Authors: Baumgartner Lee J. , Harris John H. 
Published: June 2007

AbstractAn ineffective submerged orifice fishway was retrofitted with a Deelder lock and assessed for fish passage over two consecutive years (2002–2003) at Balranald Weir on the Murrumbidgee River, Australia. The assessment, using paired entrance and exit sampling, over three different cycle times, yielded a total of 13 448 fish (11 species) and 859 freshwater prawns (one species) passing through the lock. Australian smelt Retropinna semoni Weber, bony herring Nematolosa erebi Günther and western carp gudgeon Hypseleotris spp contributed 89% of the total catch. The maximum number of fish caught in a single day was 854. Cycle time did not have a significant effect on the abundance or composition of fish using the fishlock and sizes of fish sampled from the exit trap ranged from 12 to 540 mm fork length. Length–frequency analysis also demonstrated that all size classes of the most common species were able to negotiate the lock successfully. Movement of fish varied significantly with time of the day. The greatest movement occurred between 1200 and 1600 and few fish migrated at dawn or at night. The Deelder lock improved passage for a much wider range of species and size classes than within the existing submerged orifice designs in other areas of the Murray‐Darling Basin. The design is therefore recommended for installation at other sites, especially where small‐fish passage is a priority. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of nano‐organized multilayers constituted by successive inorganic (gold) and organic (alkylthiols) layers
Authors: Kazzi Yolla , Awada Houssein , David Marie‐Odile , Nardin Michel 
Published: June 2007

AbstractNanostructured multilayers constituted by alternate metallic (gold) and organic (alkyldithiol) layers, and grafted onto glass or silicon substrates are prepared and analysed. Such complex layers could be of interest as a new type of surfaces but also as localized dissipative zones particularly in the field of adhesion science. The formation and the structure of these model systems are examined using a number of techniques such as atomic force microscopy (AFM), wetting analysis (contact angles), X‐ray photoelectron spectroscopy (XPS) and conductivity measurements. It is shown that, in terms of electrical conductivity, gold layers exhibit a percolation transition from an insulating granular structure to a conductive worm‐like structure at a threshold thickness of about 5 nm. XPS (and wettability) analyses clearly indicate that the fractional coverage of the gold surface is about 30% with alkyldithiol and that these molecules are either grafted in a stand‐up position or in the form of a loop. Moreover, a partial electrical connection between two successive gold layers is observed, confirming that the confined organic layer of alkyldithiol between them is too loosely organized to play the role of an insulating barrier. Copyright © 2007 John Wiley & Sons, Ltd.
Frequentist evaluation of group sequential clinical trial designs
Authors: Emerson Scott S. , Kittelson John M. , Gillen Daniel L. 
Published: June 2007

AbstractGroup sequential stopping rules are often used as guidelines in the monitoring of clinical trials in order to address the ethical and efficiency issues inherent in human testing of a new treatment or preventive agent for disease. Such stopping rules have been proposed based on a variety of different criteria, both scientific (e.g. estimates of treatment effect) and statistical (e.g. frequentist type I error, Bayesian posterior probabilities, stochastic curtailment). It is easily shown, however, that a stopping rule based on one of these criteria induces a stopping rule on all other criteria. Thus, the basis used to initially define a stopping rule is relatively unimportant so long as the operating characteristics of the stopping rule are fully investigated. In this paper we describe how the frequentist operating
characteristics of a particular stopping rule might be evaluated to ensure that the selected clinical trial design satisfies the constraints imposed by the many different disciplines represented by the clinical trial collaborators. Copyright © 2007 John Wiley & Sons, Ltd.
Bayesians in clinical trials: Asleep at the switch
Authors: Moyé Lemuel A. 
Published: June 2007

AbstractThe refreshing Bayes perspective has much to offer biostatistics. Yet, from its 225‐year‐old roots sprung difficulties that blocked its growth at the beginning of the 20th century. Computational obstacles in concert with an inability to identify the best indifferent prior revealed a weakness on which frequentists capitalized. It took Bayesians 40 years to recover, allowing the infant field of biostatistics to fall firmly in the hands of the frequentists. Recent disillusionment with the frequentist perspective, and its hegemony ofp‐values, has produced a second opportunity for the Bayesian philosophy to make solid contributions to clinical trials.However, difficulty with the applicability of the likelihood principle, problems with prevalent prior ‘disinformation’ in clinical medicine, in concert with the complexity of truly representative loss functions threaten again to thwart the Bayesian march into biostatistics. Seven suggestions are offered to the Bayesians to help them adapt to the rigors of clinical research. Copyright © 2007 John Wiley & Sons, Ltd.
Randomized phase II trials with a prospective control
Authors: Jung Sin‐Ho 
Published: June 2007

AbstractWe consider phase II trials randomizing patients between a prospective control and an experimental therapy. Proposed are two‐stage designs allowing for early termination of the study when the experimental arm does not show promising efficacy at the interim analysis. By using exact binomial distributions, the design characteristics, such as type I error and power, are exactly calculated. Given response probabilities for two arms, we define minimax and optimal designs that satisfy a prespecified restriction on type I and II error probabilities. These designs are randomized phase II trial analogs of Simon's designs that were proposed for single‐arm phase II trials. The methods for two‐arm trials are easily extended to multi‐arm trials with one control and K (⩾2) experimental arms. Some phase II trials are taken as real examples. Copyright © 2007 John Wiley & Sons, Ltd.