bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Amphiphilic Copolymers of Poly(ethylene oxide) and Poly(ϵ‐caprolactone) with Different Architectures, and Their Role in the Preparation of Stealthy Nanoparticles
Authors: Rieger J. , Passirani C. , Benoit J.‐P. , Van Butsele K. , Jérôme R. , Jérôme C. 
Published: June 2006

AbstractWell‐defined copolymers of biocompatible poly(ϵ‐caprolactone) (PCL) and poly(ethylene oxide) (PEO) are synthesized by two methods. Graft copolymers with a gradient structure are prepared by ring‐opening copolymerization of ϵ‐caprolactone (ϵCL) with a PEO macromonomer of the ϵCL‐type. The ϵCL polymerization is initiated by a PEO macroinitiator to prepare diblock copolymers. These amphiphilic copolymers are used as stabilizers for biodegradable poly(D,L‐lactide) (PLA) nanoparticles prepared by a nanoprecipitation technique. The effect of the copolymer characteristic features (architecture, composition, and amount) on the nanoparticle formation and structure is investigated. The average size, size distribution, and stability of aqueous suspensions of the nanoparticles is measured by dynamic light scattering. For comparison, an amphiphilic random copolymer, poly(methyl methacrylate‐co‐methacrylic acid) (P(MMA‐co‐MA)), is synthesized. The stealthiness of the nanoparticles is analyzed in relation to the copolymer used as stabilizer. For this purpose, the activation of the complement system by nanoparticles is investigated in vitro using human serum. This activation is much less important whenever the nanoparticles are stabilized by a PEO‐containing copolymer rather than by the P(MMA‐co‐MA) amphiphile. The graft copolymers with a gradient structure and the diblock copolymers with similar macromolecular characteristics (molecular weight and hydrophilicity) are compared on the basis of their capacity to coat PLA nanoparticles and to make them stealthy.
Red Phosphorescent Iridium Complex Containing Carbazole‐Functionalized β‐Diketonate for Highly Efficient Nondoped Organic Light‐Emitting Diodes
Authors: Liu Z. W. , Guan M. , Bian Z. Q. , Nie D. B. , Gong Z. L. , Li Z. B. , Huang C. H. 
Published: June 2006

AbstractA novel red phosphorescent iridium complex containing a carbazole‐functionalized β‐diketonate, Ir(DBQ)2(CBDK) (bis(dibenzo[f,h]quinoxalinato‐N,C2) iridium (1‐(carbazol‐9‐yl)‐5,5‐dimethylhexane‐2,4‐diketonate)) is designed, synthesized, and characterized. The electrophosphorescence properties of a nondoped device using the title complex as an emitter with a device configuration of indium tin oxide (ITO)/N,N′‐diphenyl‐N,N′‐bis(1‐naphthyl)‐1,1′‐diphenyl‐4,4′‐diamine (NPB; 20 nm)/iridium complex (20 nm)/2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline (BCP; 5 nm)/tris(8‐hydroxyquinoline) (AlQ; 30 nm)/Mg0.9Ag0.1 (200 nm)/Ag (80 nm) are examined. The results show that the nondoped device achieves a maximum lumen efficiency as high as 3.49 lm W–1. To understand this excellent result observed, two reference complexes Ir(DBQ)2(acac), where acac is the acetyl acetonate anion, and Ir(DBQ)2(FBDK), [bis(dibenzo[f,h]quinoxalinato‐N,C2) iridium (1‐(9‐methyl‐fluoren‐9‐yl)‐6,6‐dimethylheptane‐3,5‐diketonate)], have also been synthesized, and as emitters they were examined under the same device configuration. The maximum lumen efficiency of the former compound is found to be 0.26 lm W–1 while that for the latter is 0.37 lm W–1, suggesting that the excellent performance of Ir(DBQ)2(CBDK) can be attributed mainly to an improved hole‐transporting property that benefits the exciton transport. In addition, a bulky diketonate group separates the emitter centers from each other, which is also important for organic light‐emitting diodes.
Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by palladium complexes bridged with N,N‐ligands over functionalized silica
Authors: Fan Guo‐zhi , Li Tao , Li Guang‐xing 
Published: June 2006

AbstractHeterogeneous palladium catalysts anchored on functionalized silica were prepared by sol–gel methods and their catalytic properties for the oxidative carbonylation of phenol to diphenyl carbonate (DPC) were investigated. The catalysts were characterized by means of IR, XPS, EA and BET. The Pd loading in the heterogeneous catalysts and leaching in solution were detected by atomic absorption. The effects of different reaction parameters such as temperature, solvent and inorganic cocatalyst on the yield of DPC and Pd leaching were also studied. It was found that Cu2O and tetrahydrofuran (THF) were the best partners with these heterogeneous catalysts. In the presence of 3 Å molecular sieves as dehydrating agent, the heterogeneous palladium catalyst prepared from 2‐acylpyridine revealed excellent catalytic performance and stability at 110 °C for 5 h, giving 13.7% yield of DPC based on phenol and 4.0% Pd loss in solution. The heterogeneous catalyst was more active and stable compared with traditional supported PdC catalyst under the same reaction conditions. Copyright © 2005 John Wiley & Sons, Ltd.
Superior real time method to evaluate photo‐curing resin by means of rigid‐body pendulum rheometer
Authors: Chiu Hsien‐Tang , Cheng Ming‐Feng 
Published: June 2006

AbstractThe objective of this article is to establish a new method in evaluating photo‐polymerization resin reaction behavior, and to use the trends resulting from past evaluation methods and those already known to prove the feasibility of this method. Another objective is to compare the data gathered using the differential photo calorimeter (DPC) method and RPT on different photo‐polymerization resin systems to illustrate that the application of RPT on photo‐polymerization resin studies is more suitable. Experiment results show that the trends through the real time method using oxide series acrylate research through rigid‐body Pendulum Rheometer, the photo‐curing behavior under the various parameters of monomer functionality, and photo‐initiator concentration can all be observed. Comparing the DPC and RPT methods on polyester acrylate series, when the oligomer of tetra‐functional polyester acrylate is added with a different ratio of the monomer of propoxylated neopentyl‐glycol di‐acrylate, DPC evaluation methods show that the differences in observation are minimal. However, when RPT was applied, not only were the differences in reaction speed observed, but also the differences in crosslinking and other data in the hardening process when the balanced time was achieved during the oscillations procedure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3402–3407, 2006
Fine characterization of plasma‐polymerized films from a methane/air mixture
Authors: Mori Masaru , Izumi Hirokazu , Nakagawa Kazuharu , Nakamoto Tsuyoshi , Mori Takeshi , Kawashimo Yasushi , Ueda Yasukiyo 
Published: June 2006

AbstractThe plasma polymerization of methane/air mixtures was performed to produce a hydrophilic film on a substrate, and the obtained films were characterized with ellipsometry, elemental analysis, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, and contact‐angle measurements. Fourier transform infrared revealed that the structure of the plasma‐polymerized films changed with increasing film thickness; that is, an increase in the film thickness led to an increase in the absorbance ratio of the carbonyl band at 1664 cm−1 to the methyl band at 1385 cm−1. Although the contents of nitrogen and oxygen measured by elemental analysis changed with the film thickness, the contact angle and X‐ray photoelectron spectroscopy atomic ratio of the films were independent of it. Nitrogen and oxygen were contained in the bulk more than on the surface of the films. Nitrogen and oxygen were copolymerized with methane, and the properties of the obtained films were similar to those of an amide compound. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3408–3414, 2006
Synthesis and characterization of hyperbranched poly(silyl ester)s
Authors: Han Nianfeng , Liu Zonglin , Jin Liqiang 
Published: June 2006

AbstractHyperbranched poly(silyl ester)s were synthesized via the A2 + B4 route by the polycondensation reaction. The solid poly(silyl ester) was obtained by the reaction of di‐tert‐butyl adipate and 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The oligomers with tert‐butyl terminal groups were obtained via the A2 + B2 route by the reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl‐trisi1oxane with excess amount of di‐tert‐butyl adipate. The viscous fluid and soft solid poly(silyl ester)s were obtained by the reaction of the oligomers as big monomers with 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The polymers were characterized by 1H NMR, IR, and UV spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The 1H NMR and IR analysis proved the existence of the branched structures in the polymers. The glass transition temperatures (Tg's) of the viscous fluid and soft solid polymers were below room temperature. The Tg of the solid poly(silyl ester) was not found below room temperature but a temperature for the transition in the liquid crystalline phase was found at 42°C. Thermal decomposition of the soft solid and solid poly(silyl ester)s started at about 130°C and for the others it started at about 200°C. The obtained hyperbranched polymers did not decompose completely at 700°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3430–3436, 2006
A rheology study of high‐energy radiolysis of a semicrystalline ethylene‐propylene copolymer containing DOP mobilizer
Authors: Fuzail Mohammad , Hill David J. T. , Park Yoosup , Halley Peter 
Published: June 2006

AbstractThe radiolysis of a poly(ethylene‐co‐propylene), Elpro grade P 750 J, marketed by Thai Polypropylene Co. Ltd. for the manufacture of medical goods, was investigated at ambient temperature and melt rheology measured. The roles of calcium stearate, blended with the Elpro as a processing aid, and dioctyl phthalate (DOP), added in various amounts as a radical scavenger, were assessed. Following radiolysis, G′ and the viscosity of the polymer melts at 453 K both decreased with increasing radiation dose, even when the mobilizer was present. The results indicated that although the DOP did scavenge radicals, it did not protect the polymer from net chain scission in a low‐dose regimen. The value of (GS − 4GX) was approximately 0.6–0.7. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3437–3441, 2006
Hydroxyalkylation of barbituric acid. I. Hydroxymethyl derivatives of barbituric acid—Precursors of polyetherols with a pyrimidine ring
Authors: Ślączka Anna , Lubczak Jacek 
Published: June 2006

AbstractThe reaction of barbituric acid with formaldehyde at variable molar ratios was studied. The structure of the products was elucidated using 1H‐NMR and IR spectroscopy as well as acidic number and formaldehyde percentage analysis. The products were potential substrates for the synthesis of linear and multifunctional polyetherols with a pyrimidine ring by reaction with oxiranes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101:3468–3478, 2006
Synthesis and Antiviral Evaluation of Novel Cyclopropyl Nucleosides, Phosphonate Nucleosides and Phosphonic Acid Nucleosides
Authors: Hyun Oh Chang , Hong Joon Hee 
Published: June 2006

AbstractNovel phenyl‐branched cyclopropyl nucleosides, phosphonates, and phosphonic acid analogues were designed and synthesized as potential antiviral agents. Coupling of the mesylate 10 with natural bases (U, T, C, A) and desilylation/hydrolysis afforded a series of novel cyclopropyl nucleosides 15–18. Phosphonate and phosphonic acid nucleosides 22–29 were also readily synthesized from the mesylate 21. The synthesized compounds were evaluated for their antiviral activity against various viruses such as HIV‐1, HSV‐1, HSV‐2, and HCMV.
Synthesis and Molluscicidal Activity of New Cinnoline and Pyrano [2,3‐c]pyrazole Derivatives
Authors: Abdelrazek Fathy M. , Metz Peter , Metwally Nadia H. , El‐Mahrouky Sherif F. 
Published: June 2006

Abstract2‐(3‐Hydroxy‐5,5‐dimethylcyclohexylidene)malononitrile 5 undergoes an azo coupling reaction with aryldiazonium salts to afford 3‐amino‐2‐aryl‐6,6‐dimethyl‐8‐oxo‐2,6,7,8‐tetrahydrocinnoline‐4‐carbonitriles 7. Upon reflux in acetic acid, these compounds were acetylated to give the cinnoline derivatives 9. The pyrazolones 10a, b react with 3‐furfurylidene‐ and 3‐thienylidene‐malononitrile derivatives 11a, b to afford the pyrano[2,3‐c]pyrazole derivatives 13a–d. These newly synthesized compounds show generally a moderate molluscicidal activity to Biomphalaria alexandrina snails.
The effect of discordance among violence and general recidivism risk estimates on predictive accuracy
Authors: Mills Jeremy F. , Kroner Daryl G. 
Published: June 2006

AbstractIntroduction Previous research has shown that the prediction of short‐term inpatient violence is negatively affected when clinicians' inter‐rater agreement is low and when confidence in the estimate of risk is low. This study examined the effect of discordance between risk assessment instruments used to predict long‐term general and violence risk in offenders.Methods The Psychopathy Checklist – Revised (PCL–R), Level of Service Inventory – Revised (LSI–R), Violence Risk Appraisal Guide (VRAG), and the General Statistical Information on Recidivism (GSIR) were the four risk‐prediction instruments used to predict post‐release general and violent recidivism within a sample of 209 offenders.Results The findings lend empirical support to the assumption that predictive accuracy is threatened where there is discordance between risk estimates. Discordance between instruments had the impact of reducing predictive accuracy for all instruments except the GSIR. Further, the influence of discordance was shown to be greater on certain instruments over others. Discordance had a moderating effect on both the PCL–R and LSI–R but not on the VRAG and GSIR.Conclusions There is a distinct advantage when attempting to predict recidivism to employing measures such as the LSI‐R, which includes dynamic variables and intervention‐related criminogenic domains, over a measure purely of fixed characteristics, such as the GSIR; however, if there is discordance between the risk estimates, caution should be exercised and more reliance on the more static historically based instrument may be indicated. Copyright © 2006 John Wiley & Sons, Ltd.
Active Site Comparison of CoII Blue and Green Nitrite Reductases
Authors: Sato Katsuko , Dennison Christopher 
Published: June 2006

AbstractCopper‐containing nitrite reductases (NiRs) possess type 1 (T1) and type 2 (T2) copper sites and can be either green or blue in color owing to differences at their T1 centers. The active sites of a green and a blue NiR were studied by utilizing their T1CuI/T2CoII and T1CoII/T2CoII‐substituted forms. The UV/Vis spectra of these derivatives highlight the similarity of the T2 centers in these enzymes and that T1 site differences are also present in the CoII forms. The paramagnetic NMR spectra of T1CuI/T2CoII enzymes allow hyperfine shifted resonances from the three T2 His ligands to be assigned: these exhibit remarkably similar positions in the spectra of both NiRs, emphasizing the homology of the T2 centers. The addition of nitrite results in subtle alterations in the paramagnetic NMR spectra of the T1CuI/T2CoII forms at pH<7, which indicate a geometry change upon the binding of substrate. Shifted resonances from all of the T1 site ligands have been assigned and the CoIIN(His) interactions are alike, whereas the CβH proton resonances of the Cys ligand exhibit subtle chemical shift differences in the blue and green NiRs. The strength of the axial CoIIS(Met) interaction is similar in the two NiRs studied, but the altered conformation of the side chain of this ligand results in a dramatically different chemical shift pattern for the CγH protons. This indicates an alteration in the bonding of the axial ligand in these derivatives, which could be influential in the CuII proteins.
Synthesis of Extended Triphenylenes by Palladium‐Catalyzed [2+2+2] Cycloaddition of Triphenylynes
Authors: Romero Carmen , Peña Diego , Pérez Dolores , Guitián Enrique 
Published: June 2006

AbstractThe synthesis of ortho‐(trimethylsilyl)triphenylenyl triflates 7 is described. Fluoride‐induced decomposition of these triflates leads to the generation of didehydrotriphenylenes (triphenylynes) 6. These arynes undergo [4+2] cycloadditions with dienes to afford the corresponding Diels–Alder adducts or palladium‐catalyzed formal [2+2+2] cycloadditions to afford extended triphenylenes.
Chiral Poly(ureidophthalimide) Foldamers in Water
Authors: Sinkeldam Renatus W. , van Houtem Michel H. C. J. , Pieterse Koen , Vekemans Jef A. J. M. , Meijer E. W. 
Published: June 2006

AbstractPoly(ureidophthalimide)s decorated with hydrophilic side chains, that ensure solubility in aqueous media, have been synthesized and characterized by UV/Vis and circular dichroism (CD) spectroscopy. Temperature and concentration dependent CD measurements in water have revealed an almost temperature and concentration independent Cotton effect, indicative for a strong intramolecular organization. Similar studies in THF demonstrate the dynamic nature of the secondary architecture, a characteristic of foldamers. In addition, the bisignated Cotton effect in water is opposite in sign to that in THF, suggestive for a solvent‐dependent preference for one helical handedness. Mixing experiments prove the dominance of water in determining the handedness of the helical architecture. The solvent allows for control over the helical architecture and thus governs the supramolecular synthesis.
Ligand Variations in [ReX(diimine)(CO)3] Complexes: Effects on Photocatalytic CO2 Reduction
Authors: Kurz Philipp , Probst Benjamin , Spingler Bernhard , Alberto Roger 
Published: June 2006

AbstractTwo series of complexes [MX(diimine)(CO)3] (M = Tc, Re) have been prepared, fully characterised and investigated for their ability to act as photocatalysts for the reduction of CO2 to CO. One series consists of complexes with different aromatic diimine ligands while keeping X = Br– constant. The second series describes complexes with diimine = 2,2‐bipyridine and variations in the anionic ligand X–. Although numerous complexes of this type have been prepared and investigated before, a systematic study of their photocatalytic activity has not yet been carried out. Electrochemical and spectroscopic characterisation of these complexes has been performed with the objective of better understanding their respective activity in the photocatalytic CO2 reduction.Despite various modifications, catalytic activity is retainedfor all compounds exhibiting fluorescence, including [99TcCl(bipy)(CO)3], whereas nonfluorescing compounds did not convert CO2 to CO. The correlation of catalytic activity and spectroscopic or electrochemical properties such as absorption or emission wavelengths, redox potentials or Stern–Volmer constants for the reductive quenching of the excited complexes is difficult. Nevertheless, the study emphasises the possibility to obtain [ReX(CO)3(diimine)] complexes with a wide range of physicochemical properties by ligand variations and the great potential of compounds of this class of complexes as inorganic photosensitisers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Platinum Complexes with One Monodentate Ligand (1‐Methylbenzimidazole or Antiviral Ribavirin) Flanked by Two cis‐NMe2 Groups: Informative Models for Assessing Interligand Interactions
Authors: Cerasino Leonardo , Natile Giovanni 
Published: June 2006

AbstractPlatinum complexes with a tridentate amine ligand (A3) and a nucleobase (L) represent very useful models for investigating nucleobase/cis‐amine interactions without the complications arising from nucleobase/nucleobase interferences present in the more frequently used cis‐A2PtL2 model systems (A2 = two monodentate amines or a diamine). In this context, the Me3dienPtL complexes (Me3dien = N1,N4,N7‐trimethyldiethylenetriamine), previously investigated, were particularly informative. The presence of a methyl group on each terminal nitrogen atom renders the rotation of L about the Pt–L bond slow on the NMR timescale and the two half spaces defined by the coordination plane inequivalent. Thus, guanine and deoxyguanine derivatives were found to have comparable rates of rotation by way of a H‐bond interaction between the O6 atom of the rotating guanine and the NH group of the cis‐amine. We have now extended the investigation to Me5dien complexes (Me5dien = N1,N1′,N4,N7,N7′‐pentamethyldiethylenetriamine). The results indicate that the absence of a proton on the terminal nitrogen atoms not only reduces the rate of rotation of L by a factor of 1010, but also dramatically increases the difference in the rates between the L ligands mimicking guanine and deoxyguanine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Controlling the Size of BaF2 Nanocubes from 1000 to 10 nm
Authors: Gao Peng , Xie Yi , Li Zhen 
Published: June 2006

AbstractSize control of BaF2 nanocubes has been achieved by varying reaction time and pH value, thus producing nanocubes with a controllable edge length in the range 10–1000 nm. A linear relationship between cube size and reaction time has been revealed. Furthermore, a process has been developed to separate the growing BaF2 nanocubes from the remaining solid products at different stages of the synthesis. On the basis of the observed crystallite morphologies, we have elucidated an “extension growing” mechanism to describe the size‐controlled growth of BaF2 nanocubes using this method. Photoluminescence results demonstrate that the deoxidant selenite ions prevent the incorporation of oxygen into the BaF2 nanocubes effectually, which will greatly affect their performance as scintillators. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Thin Film Microelectrodes in SOFC Electrode Research
Authors: Fleig J. , Baumann F. S. , Brichzin V. , Kim H.‐R. , Jamnik J. , Cristiani G. , Habermeier H.‐U. , Maier J. 
Published: June 2006

AbstractExperimental studies using conventional (porous) solid oxide fuel cell (SOFC) electrodes are often rather difficult to interpret in terms of a mechanistic understanding of the electrochemical polarization phenomena. Owing to the complex morphology and structure of porous electrodes, a quantitative determination of the properties of the electrochemical materials rather than of the effective electrode properties is far from being straightforward. Micro‐patterned epitaxially grown thin film electrodes offer new possibilities in this field of research. This is particularly true for microelectrodes of several 10 μm diameter, fabricated lithographically from thin films. They allow well‐defined geometry‐dependent experiments, minimize the importance of ohmic drops, and avoid the necessity of a reference electrode. Further, they turn out to be particularly well‐suited for statistical studies, as well as for the investigation of irreversible processes. Hence, thin‐film microelectrodes are an excellent tool for the investigation of SOFC electrode materials. This is exemplified by p(O2)‐, voltage‐, and geometry‐dependent measurements on (La0.8Sr0.2)0.92MnO3 and La0.6Sr0.4Co0.8Fe0.2O3–δ microelectrodes on single‐crystal yttria‐stabilized zirconia electrolytes.