bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Angle Electroluminescence of Light‐Emitting Diodes based on Nanostructured ZnO/GaN Heterojunctions
Authors: Fu Hang‐Kuei , Cheng Cheng‐Liang , Wang Chun‐Hsiung , Lin Tai‐Yuan , Chen Yang‐Fang 
Published: September 2009

AbstractSelective angle electroluminescence of violet light with a peak wavelength of 405 nm from light‐emitting diodes based on nanostructured p‐GaN/ZnO heterojunctions is reported. The fabrication of well‐aligned nanobottles with excellent crystalline quality is achieved by chemical vapor deposition at temperatures as low as 450 °C with a specially designed upside‐down arrangement of substrate configuration. Selective angle light sources are essential in our daily life. With the geometry of the nanobottle waveguides, it is very easy to realize such a practical application. Therefore, the discovery reported here should be very useful for the future development of many unique optoelectronic devices.
Multiresponsive PEDOT–Ionic Liquid Materials for the Design of Surfaces with Switchable Wettability
Authors: Döbbelin Markus , Tena‐Zaera Ramon , Marcilla Rebeca , Iturri Jagoba , Moya Sergio , Pomposo Jose A. , Mecerreyes David 
Published: September 2009

AbstractAmong the different types of stimuli‐responsive polymers, conjugated polymers reveal unique multiresponsive behavior. In this work, the synthesis and characterization of new functional poly(3,4‐ethylenedioxythiophenes) (PEDOT) bearing imidazolium ionic‐liquid moieties (PEDOT‐Im) is reported. PEDOT‐Im polymers show multiresponsive properties to a variety of stimuli, such as temperature, pH, oxidative doping, and presence of anions. These stimuli provoke different changes in PEDOT‐Im, such as changes in color, oxidation state, and, wetting behavior. In all cases, a reversible effect is observed, and the polymers reveal responsive properties in solution as well as in the form of thin films. Whereas sensitiveness to pH and oxidative doping are known phenomena for other PEDOT derivatives, responsiveness to temperature and to anions is a unique property of PEDOT‐Im. The anion exchange is further investigated by means of the Quartz Crystal Microbalance with dissipation. Anion exchanges induce fast, adjustable, and reversible contact angle changes between 24° and 107°. As a potential application, surfaces with switchable wettability triggered by anion solutions are prepared by spin‐coating PEDOT‐Im films onto different substrates.
Dye‐Doped Polyhedral Oligomeric Silsesquioxane (POSS)‐Modified Polymeric Matrices for Highly Efficient and Photostable Solid‐State Lasers
Authors: Sastre Roberto , Martín Virginia , Garrido Leoncio , Chiara José Luis , Trastoy Beatriz , García Olga , Costela Angel , García‐Moreno Inmaculada 
Published: September 2009

AbstractHere, the design, synthesis, and characterization of laser nanomaterials based on dye‐doped methyl methacrylate (MMA) crosslinked with octa(propyl‐methacrylate) polyhedral oligomeric silsesquioxane (8MMAPOSS) is reported in relation to their composition and structure. The influence of the silicon content on the laser action of the dye pyrromethene 567 (PM567) is analyzed in a systematic way by increasing the weight proportion of POSS from 1 to 50%. The influence of the inorganic network structure is studied by replacing the 8MMAPOSS comonomer by both the monofunctionalized heptaisobutyl‐methacryl‐POSS (1MMAPOSS), which defines the nanostructured linear network with the POSS cages appearing as pendant groups of the polymeric chains, and also by a new 8‐hydrogenated POSS incorporated as additive to the polymeric matrices. The new materials exhibit enhanced thermal, optical, and mechanical properties with respect to the pure organic polymers. The organization of the molecular units in these nanomaterials is studied through a structural analysis by solid‐state NMR. The domain size of the dispersed phase assures a homogeneous distribution of POSS into the polymer, thus, a continuous phase corresponding to the organic matrix incorporates these nanometer‐sized POSS crosslinkers at a molecular level, in agreement with the transparency of the samples. The silicon–oxygen core framework has to be covalently bonded into the polymer backbone instead of being a simple additive and both the silica content and crosslinked degree exhibit a critical influence on the laser action.
Preparation of Inorganic Materials Using Ionic Liquids
Authors: Ma Zhen , Yu Jihong , Dai Sheng 
Published: September 2009

AbstractConventional synthesis of inorganic materials relies heavily on water and organic solvents. Alternatively, the synthesis of inorganic materials using, or in the presence of, ionic liquids represents a burgeoning direction in materials chemistry. Use of ionic liquids in solvent extraction and organic catalysis has been extensively studied, but their use in inorganic synthesis has just begun. Ionic liquids are a family of non‐conventional molten salts that can act as templates and precursors to inorganic materials, as well as solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility for both organic and inorganic molecules, and much synthetic flexibility. In this Review, the use of ionic liquids in the preparation of several categories of inorganic and hybrid materials (i.e., metal structures, non‐metal elements, silicas, organosilicas, metal oxides, metal chalcogenides, metal salts, open‐framework structures, ionic liquid‐functionalized materials, and supported ionic liquids) is summarized. The status quo of the research field is assessed, and some future perspectives are furnished.
A Diversified Library of Bacterial and Fungal Bifunctional Cytochrome P450 Enzymes for Drug Metabolite Synthesis
Authors: Weis Roland , Winkler Margit , Schittmayer Matthias , Kambourakis Spiros , Vink Mandy , Rozzell J. David , Glieder Anton 
Published: September 2009

AbstractInnovative biohydroxylation catalysts for the preparation of drug metabolites were developed from scratch. A set of bacterial and fungal sequences of putative and already known bifunctional P450 enzymes was identified by protein sequence alignments, expressed in Escherichia coli and characterised. Notably, a fungal self‐sufficient cytochrome P450 (CYP) from Aspergillus fumigatus turned out to be especially stable during catalyst preparation and application and also in presence of organic co‐solvents. To enhance the catalytic activity and broaden the substrate specificity of those variants with high expression levels prominent single mutations were introduced. Selected improved variants were then used as lyophilised bacterial lysates for the synthesis of 4′‐hydroxydiclofenac and 6‐hydroxychlorzoxazone, the two metabolites of active pharmaceutical compounds diclofenac and chlorzoxazone representing the same metabolites as generated by human P450s.
Samarium Powder‐Catalyzed Palladium‐Free and Ligand‐Free Sonogashira Coupling Reactions
Authors: Mao Jincheng , Wu Minyan , Xie Guanlei , Ji Shunjun 
Published: September 2009

AbstractA study of samarium powder‐catalyzed cross‐coupling reactions of aryl halides with terminal alkynes is described. The couplings performed in the polyethylene glycol PEG‐600 provided the corresponding coupling products in good yields. The first example of palladium‐free, copper‐free and amine‐free catalytic system for Sonogashira couplings is presented in the absence of ligand.
Chiral Polyamino Alcohols via Hydroaminomethylation: A New Class of Polyamines for Dendritic Cores and Ligand Precursors
Authors: Subhani Muhammad Afzal , Müller Kai‐Sven , Eilbracht Peter 
Published: September 2009

AbstractIn this contribution, the synthesis of a new class of chiral polyamino alcohols (PAA) via a two‐step hydroaminomethylation/hydrolysis procedure is reported. The chiral polyamines are obtained by hydroaminomethylation of N‐olefinic oxazolidinones with different amines in first step followed by hydrolysis of the resulting polyamines to give the chiral PAA in the second step. The dendritic chiral PAA (Mw=1300–1400 g mol−1) are also synthesized efficiently through a multifold hydroaminomethylation/hydrolysis procedure. Furthermore, chiral PAA are investigated as ligands in ruthenium‐catalyzed asymmetric hydrogen transfer reduction of acetophenone to 1‐phenyl alcohol.
“Click” Polymer‐Supported Palladium Nanoparticles as Highly Efficient Catalysts for Olefin Hydrogenation and Suzuki Coupling Reactions under Ambient Conditions
Authors: Ornelas Cátia , Diallo Abdou K. , Ruiz Jaime , Astruc Didier 
Published: September 2009

AbstractComplexation of palladium(II) acetate [Pd(OAc)2] or dipotassium tetrachloropalladate [K2PdCl4] to “click” polymers functionalized with phenyl, ferrocenyl and sodium sulfonate groups gave polymeric palladium(II)‐triazolyl complexes that were reduced to “click” polymer‐stabilized palladium nanoparticles (PdNPs). Transmission electron microscopy (TEM) showed that reduction using sodium borohydride (NaBH4) produced PdNPs in the 1–3 nm range of diameters depending on the nature of the functional group, whereas slow reduction using methanol yielded PdNPs in the 22–25 nm range. The most active of these PdNPs (0.01% mol Pd), stabilized by poly(ferrocenyltriazolylmethyl)styrene, catalyzed the hydrogenation of styrene at 25 °C and 1 atm hydrogen, with turnover numbers (TONs) of 200,000. When stabilized by the water‐soluble poly(sodium sulfonate‐triazolylmethyl)styrene, the PdNPs (0.01% mol Pd) catalyze the Suzuki–Miyaura coupling between iodobenzene (PhI) and phenylboronic acid [PhB(OH)2] in water/ethanol (H2O/EtOH) at 25 °C with TONs of 8,200. This high catalytic activity is comparable to that obtained with “click” dendrimer‐stabilized PdNPs under ambient conditions.
A Symmetry‐Based Synthesis of the Heterobicyclic Core of the Zaragozic Acids/Squalestatins
Authors: Wang Yuzhou , Kataeva Olga , Metz Peter 
Published: September 2009

AbstractThe pseudo C2‐symmetrical diketone 22 was efficiently constructed from furan‐3,4‐dimethanol (7) using a two‐directional route featuring a double asymmetric dihydroxylation. Acidic hydrolysis of the cyclopentylidene acetals of 22 triggered a selective cyclization of the resulting hexaol diketone to generate the 2,8‐dioxabicyclo[3.2.1]octane core of the zaragozic acids/squalestatins. Chemoselective oxidative cleavage of a superfluous two‐carbon appendage and further functional group manipulations yielded the enantiomerically pure triester 30, which offers itself as a general heterobicyclic building block for naturally occurring zaragozic acids/squalestatins and unnatural analogues.
Diethylzinc: A Simple and Efficient Catalyst for the Swift Hydroamination at Room Temperature
Authors: Pissarek Jens‐Wolfgang , Schlesiger David , Roesky Peter W. , Blechert Siegfried 
Published: September 2009

AbstractDiethylzinc and dimethylanilinium tetrakis(pentafluorophenyl)borate were found to catalyze hydroaminations at room temperature in high efficiency and very short reaction times. The reactivity of the proposed cationic zinc species, which is assumed to catalyze the reaction, strongly depends on the coordinative abilities of the counterion.
Cross‐Linked Enzyme Aggregates of Chloroperoxidase: Synthesis, Optimization and Characterization
Authors: Perez Daniel I. , van Rantwijk Fred , Sheldon Roger A. 
Published: September 2009

AbstractIn this study we have optimized the conditions to precipitate and cross‐link the enzyme chloroperoxidase (EC 1.11.1.10) from Caldariomyces fumago (CPO) using 1,2‐dimethoxyethane as the precipitating agent. The coprecipitation of the enzyme with albumin and pentaethylenehexamine was needed for optimum results, presumably due to the low number of lysines available in CPO. The enzyme was immobilized with an activity recovery of 68%. The cross‐linked enzyme aggregate showed higher temperature and pH stability, and better hydrogen peroxide tolerance than the free enzyme.
An Efficient Combined Electrochemical and Ultrasound Assisted Synthesis of Imidazole‐2‐Thiones
Authors: Feroci Marta , Orsini Monica , Inesi Achille 
Published: September 2009

AbstractThe electrochemical reduction of 1,3‐dialkylimidazolium ionic liquids gave the corresponding N‐heterocyclic carbenes that, after reaction with elemental sulfur and ultrasound irradiation, yielded 1,3‐dialkylimidazole‐2‐thiones in very high yields. The reaction is very clean, produces no side‐products and avoids the use of any other added reagent.
Ruthenium‐Catalyzed Oxidative Homo‐Coupling of 2‐Arylpyridines
Authors: Guo Xiangyu , Deng Guojun , Li Chao‐Jun 
Published: September 2009

AbstractA ruthenium‐catalyzed oxidative homo‐coupling reaction of 2‐arylpyridines via CH activation was developed. The reaction could tolerate various functional groups on both the aryl and the pyridyl rings to afford a series of dimerized products with iron(III) chloride (FeCl3) as a stoichiometric oxidant. A tentative mechanism was proposed for this oxidative CH/CH homo‐coupling.
Optimization of multicomponent photopolymer formulations using high‐throughput analysis and kinetic modeling
Authors: Johnson Peter M. , Bowman Christopher N. , Stansbury Jeffrey W. 
Published: September 2009

AbstractWhile high throughput and combinatorial techniques have played an instrumental role in materials development and implementation, numerous problems in materials science and engineering are too complex and necessitate a prohibitive number of experiments, even when considering high throughput and combinatorial approaches, for a comprehensive approach to materials design. Here, we propose a unique combination of high throughput experiments focused on binary formulations that, in combination with advanced modeling, has the potential to facilitate true materials design and optimization in ternary and more complex systems for which experiments are never required. Extensive research on the development of photopolymerizable monomer formulations has produced a vast array of potential monomer/comonomer, initiator and additive combinations. This array dramatically expands the range of material properties that are achievable; however, the vast number of potential formulations has eliminated any possibility of comprehensive materials design or optimization. This limitation is addressed by maximizing the benefits and unique capabilities of high throughput experimentation coupled with predictive models for material behavior and properties. The high throughput experimentation‐model combination is useful to collect a limited amount of data from as few as 11 experiments on binary combinations of 10 analyzed monomers, and then use this limited data set to predict and optimize formulation properties in ternary resins that would have necessitated at least 1000 high throughput experiments and several orders of magnitude greater numbers of traditional experiments. A data analysis approach is demonstrated, and the model development and implementation for one model application in which a range of material properties are prescribed, and an optimal formulation that meets those properties is predicted and evaluated. © 2009 American Institute of Chemical Engineers AIChE J, 2010
Occupational health crossing borders—Part 1: Concept, teaching methods, and user evaluation of the first international summer school in Munich, Germany
Authors: Radon Katja , Ehrenstein Vera , Bigaignon‐Cantineau Janine , Vellore Arun Dev , Fingerhut Marilyn , Nowak Dennis ,   and the Occupational Health Crossing Borders Summer School Team
Published: September 2009

AbstractBackgroundOccupational health and safety (OHS) is relevant for occupational health professionals (OHP) throughout the world. However, training opportunities are often limited and exchange between OHP from industrialized and developing countries is sparse. We aimed to contribute to the international exchange of OHP through a 2‐week summer school program.MethodsTwenty‐three OHP from 11 countries participated. Teaching methods included interactive lectures, participants' presentations, case‐based e‐learning, enterprise visits, and hands‐on sessions. After completion, participants evaluated the course.ResultsOHS systems of 18 different countries were presented using the same set of clinical cases as a starting point. Opportunities and challenges in the different OHS systems were considered. On median, participants rated the course as excellent and totally agreed that it will help them in their daily work.ConclusionsAn international summer school teaching basic aspects of different OHS systems is a useful tool for training and exchange at the global level. Am. J. Ind. Med. 52:774–781, 2009. © 2009 Wiley‐Liss, Inc.
Synthesis and characterization of a lactic acid‐based thermoset resin suitable for structural composites and coatings
Authors: Åkesson Dan , Skrifvars Mikael , Seppälä Jukka , Turunen Minna , Martinelli Anna , Matic Aleksandar 
Published: September 2009

AbstractA new biobased polyester resin was developed for thermoset composite applications. The resin is potentially inexpensive and can be produced industrially by relatively simple means. The resin consists of star‐shaped methacrylated oligomers of lactic acid (LA). LA oligomers were synthesized in a two‐step process: in the first step, oligomers of LA were polymerized by direct condensation of LA. In the second step, the oligomers were end‐functionalized by methacrylic anhydride. The resin was characterized by differential scanning calorimetry, Raman spectroscopy, NMR, rubber process analyzer, and TOF‐SIMS. Tests show that the resin can be crosslinked into a rigid network within a couple of minutes upon thermal initiation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Shielding and dielectric properties of sulfonic acid‐doped π‐conjugated polymer in 8.2–12.4 GHz frequency range
Authors: Ohlan Anil , Singh Kuldeep , Dhawan S. K. 
Published: September 2009

AbstractThis article deals with dielectric and electromagnetic interference shielding properties of the polyaniline doped with dodecyl benzene sulfonic acid (DBSA) synthesized by microemulsion polymerization of aniline in aqueous solution of DBSA. Dielectric constant and shielding effectiveness due to absorption (SEA) were calculated using S‐parameter obtained from the vector network analyzer in 8.2–12.4 GHz frequency range. Maximum SEA of 26 dB (>99%) was achieved for polymer sample. The real part ε′ of complex permittivity shows small variation, whereas the imaginary part ε″ is found to decrease with the increase in frequency. Different formulations have been performed to see the effect of monomer to dopant ratio on intrinsic properties of polyaniline. Further characterization of polymer was carried out by UV–visible and thermal gravimetric analysis, whereas the conductivity measurements were carried out by the four‐probe method.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effects of alkali on properties of nanoscale 2,9 dimethyl quinacridone/poly(styrene‐maleic acid) composite dispersion
Authors: Shao‐Hai Fu , Chang‐Hai Xu 
Published: September 2009

AbstractNanoscale 2,9 dimethyl quinacridone (P.R.122) encapsulated by copolymer of styrene and maleic acid (PSMA) was prepared via phase separation technique followed by the preparation of composite dispersions. Experimental results showed that sodium hydroxide provided the dispersion the smallest particle size and the highest stability when compared with other additives, regardless of it being taken as dispersant or the other neutralization reagent. An optimal process was attained by using sodium hydroxide with a dosage of 0.60 times of molar amount of COOH groups in PSMA when P.R.122/PSMA composite dispersion was treated at 45°C for 30 min. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Rheology of poly(vinyl chloride) plastisol: Effect of a particular nonionic cosurfactant
Authors: Tomás A. , Rasteiro M. G. , Gando‐Ferreira L. , Figueiredo S. 
Published: September 2009

AbstractThe rheology of poly(vinyl chloride) plastisols is affected by many aspects of the formulations, such as type and concentration of each component, temperature and, perhaps most important, the polymer properties. Taking into consideration the surfactants normally present during the polymerization reaction, in this work, a different approach was followed. Besides the usual polymerization surfactants, a particular ester‐type emulsifier was also added in a postpolymerization stage. The results show a particle aggregation effect in the initial aqueous dispersion (latex) that promotes a significant decrease in the viscosity level, aging profile, and different viscoelastic properties of the latter plastisols. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Polypropylene/combinational inorganic filler micro‐/nanocomposites: Synergistic effects of micro‐/nanoscale combinational inorganic fillers on their mechanical properties
Authors: Chen Deliang , Yang Huaming 
Published: September 2009

AbstractPolypropylene (PP) has wide applications in various areas, but its low‐temperature brittleness and low moduli have limited its applications in engineering areas. This article reported micro‐/nanoscale combinational inorganic fillers (CIFs) to reinforce PP‐matrix composites as the first example. The CIFs consisted of plate‐like talc (T), needle‐like wollastonite (W), and nano‐Al2O3 (N). The PP/CIFs specimens were fabricated via a process of twin‐screw extrusion and screw‐type injection molding. The mechanical properties and thermal deflection temperature (HDT) of the PP/CIF composites were tested according to the corresponding standards, and the morphologies of the tensile‐fractured sections were observed using FE‐SEM. The PP/WT composites had higher mechanical properties and HDTs than those of either PP/W or PP/T. Small amounts of Al2O3 nanocrystals together with WT simultaneously strengthened and toughened the PP‐matrix composites. The PP/WTN composite with 2.6% of nano‐Al2O3 had well‐balanced properties, enhanced by a large increment when compared with the PP matrix or PP/WT composites. The enhancements should be attributed to the synergistic effects of the CIFs not only in the aspect of various shapes (plate‐like, needle‐like, and spherical) but also in hierarchical size‐levels (microscale and nanoscale). The novel strategy overcame the limitation of conventional rigid modification and solved the problem of uniform dispersion of nanocrystals in polymer matrices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of polydimethylsiloxane‐containing block copolymers via reversible addition fragmentation chain transfer (RAFT) polymerization
Authors: Wadley Maurice L. , Cavicchi Kevin A. 
Published: September 2009

AbstractLow polydispersity polydimethylsiloxane (PDMS) was end functionalized with a reversible addition fragmentation chain transfer (RAFT) agent by the esterification of hydroxyl terminated PDMS with a carboxylic acid functional RAFT agent. These PDMS‐RAFT agents were able to control the free radical polymerization of styrene and substituted styrene monomers to produce PDMS‐containing block copolymers with low polydispersities and targeted molecular weights. A thin film of polydimethylsiloxane‐block‐polystyrene was prepared by spin coating and exhibited a microphase separated morphology from scanning force microscopy measurements. Controlled swelling of these films in solvent vapor produced morphologies with significant long‐range order. This synthetic route will allow the straightforward production of PDMS‐containing block copolymer libraries that will be useful for investigating their thin film morphological behavior, which has applications in the templating of nanostructured materials.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010