bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selectivity Control in Gold‐Mediated Esterification of Methanol
Authors: Xu Bingjun , Liu Xiaoying , Haubrich Jan , Madix Robert J. , Friend Cynthia M. 
Published: February 2009

AbstractThe Midas touch: The low‐temperature transformation of methanol to methyl formate, formaldehyde, and formic acid is promoted by atomic oxygen adsorbed on metallic gold (see picture). The reactions occur with O‐containing Au nanoparticles formed on Au(111) upon oxidation with ozone at 200 K; the facile esterification to methyl formate occurs well below room temperature.magnified image
Engineering Bisquinolinium/Thiazole Orange Conjugates for Fluorescent Sensing of G‐Quadruplex DNA
Authors: Yang Peng , De Cian Anne , Teulade‐Fichou Marie‐Paule , Mergny Jean‐Louis , Monchaud David 
Published: February 2009

AbstractLighting up: A G‐quadruplex‐specific fluorescent probe was designed combining the specificity of the pyridodicarboxamide motif for guanine quadruplexes and the fluorescence properties of thiazole orange. While the assembly of the two partners through a flexible linker leads to a nonselective probe, merging them in a single, rigid scaffold leads to a dye that elicits the properties required for G‐quadruplex sensing.magnified image
Rhodium(I)‐Catalyzed Intramolecular Carbonylative [2+2+1] Cycloaddition of Bis(allene)s: Bicyclo[6.3.0]undecadienones and Bicyclo[5.3.0]decadienones
Authors: Inagaki Fuyuhiko , Narita Syu , Hasegawa Takuma , Kitagaki Shinji , Mukai Chisato 
Published: February 2009

AbstractNo templates needed: The title reaction makes it easy to construct the bicyclo[6.3.0]undecadienone framework in high yields (see scheme). A template effect is not required to achieve this ring‐closing reaction efficiently. The present method can be applied to the construction of bicyclo[5.3.0] and bicyclo[4.3.0] ring systems. Ts=p‐toluenesulfonyl.magnified image
Asymmetric Ring‐Closing Metathesis with a Twist
Authors: Klare Hendrik F. T. , Oestreich Martin 
Published: February 2009

AbstractA double flip! The catalyst shown, with a molybdenum stereocenter and monodentate ligands (Si=SitBuMe2), promotes asymmetric ring‐closing metathesis of a broad range of substrates. Its unprecedented activity originates from its structural fluxionality, which enables double inversion at the metal center in the course of a single catalytic cycle. The catalyst passed the test in a metathesis reaction en route to (+)‐quebrachamine (see scheme).magnified image
Influence of cleaning conditions on the degradation of recycled HDPE
Authors: Santana R. M. C. , Gondim G. 
Published: February 2009

AbstractOne of the materials most commonly found in municipal plastic waste (MPW) is High Density Polyethylene (HDPE), which is used particularly for food packaging and cleaning product containers. Postconsumer HDPE is generally contaminated with other impurities and, therefore, a cleaning process is necessary before it can be reprocessed. The aim of this study was to investigate the influence of the cleaning conditions on the oxidative degradation of postconsumer HDPE. These plastic materials were washed in NaOH solution, liquid detergent (D), and a mixture of NaOH/D (1 : 1). Results for the melt flow rate (MFR) and capillary rheometry showed that NaOH has a great influence on the oxidative degradation of HDPE. The HDPE treated with NaOH solution had a lower decomposition temperature, observed through Thermal Gravimetric (TG) analysis, and a lower the Oxidative Induction Time (OIT), obtained via Differential Scanning Calorimeter (DSC). Finally, the oxidative degradation of HDPE was verified through a higher carbonyl index. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of polysaccharide based graft copolymer by using potassium peroxymonosulphate/ascorbic acid as an efficient redox initiator in inert atmosphere
Authors: Kumar Rajesh , Srivastava Arti , Behari Kunj 
Published: February 2009

AbstractPolysaccharide based graft copolymer (xanthan gum‐g‐4‐vinyl pyridine) was synthesized using potassium peroxymonosulphate/ascorbic acid redox initiator in inert atmosphere at 40°C. By studying the effect of the concentration of monomer, peroxymonosulphate (PMS), ascorbic acid (AA), xanthan gum (XOH), hydrogen ion along with effect of time and temperature on grafting characteristics: grafting ratio (%G), add on (%A), conversion (%C), efficiency (%E), homopolymer (%H), and rate of grafting (Rg), the reaction conditions for optimum grafting were determined. The optimum concentration of AA, H+ ion, 4‐VP for maximum grafting were found to be 10.0 × 10−3 mol dm−3, 2.5 × 10−2 mol dm−3, 10.0 × 10−3 mol dm−3, respectively. Maximum %G was obtained at minimum concentration of xanthan gum i.e., at 40.0 × 10−2 g dm−3 and at maximum concentration of PMS i.e., at 10.0 × 10−3 mol dm−3. The optimum temperature and time duration of reaction for maximum % of grafting were found to be 45°C and 120 min respectively. The synthesized graft copolymer was characterized by FTIR analysis. Thermogravimetric analysis showed that the xanthan gum‐g‐4‐vinyl pyridine is thermally more stable than pure gum. A probable mechanism was suggested for the graft copolymerization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of nanoclay and coupling agent on the physical and mechanical properties of polypropylene/bagasse nanocomposite
Authors: Nourbakhsh Amir , Ashori Alireza 
Published: February 2009

AbstractIn this work, the effects of nanoclay (1–4 wt %) and coupling agent (2 and 4 wt %) loading on the physical and mechanical properties of nanocomposites are investigated. Composites based on polypropylene (PP), bagasse flour, and nanoclay (montmorillonite type) was made by melt compounding and then compression molding. When 1–3 wt % nanoclay was added, the tensile properties increased significantly, but then decreased slightly as the nanoclay content increased to 4%. The impact strength was 6% lower by the addition of 1 wt % nanoclay, it was decreased further when the nanoclay content increased from 1 to 4%. Finally, the water absorption of PP/bagasse composites was lowered with the increase in nanoclay content. Additionally, the coupling agent, 4 wt % MAPP, improved the mechanical and physical properties of the composites more than the 2 wt % MAPP. From these results, we can conclude that addition of nanoclay enables to achieve better physical and mechanical properties in conventional composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Phenol–formaldehyde‐type resins made from phenol‐liquefied wood for the bonding of particleboard
Authors: Hassan El Barbary , Kim Moon , Wan Hui 
Published: February 2009

AbstractLiquefaction of southern pine wood in phenol in 30–40 : 70–60 weight ratios resulted in homogeneous liquefied materials, which were directly used to synthesize phenol–formaldehyde (PF)‐type resins. The synthesized resins showed good physical and handling properties: low viscosity, stability for storage and transportation, and resin applicable by a common sprayer. Particleboard panels bonded with the synthesized resins showed promising physical properties and significantly lower formaldehyde emission values than those bonded with the urea–formaldehyde resin control. One deficiency observed for the synthesized resins was lower internal bond values, which might be overcome the use of a hot‐stacking procedure. Overall, the process of wood liquefaction with limited amounts of phenol as a solvent was shown to have the potential of providing practical, low‐cost PF‐type resins with very low formaldehyde emission potentials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization of PVAc/TiO2 hybrid nanofibers: From fibrous morphologies to molecular structures
Authors: Wu Ning , Shao Dongfeng , Wei Qufu , Cai Yibing , Gao Weidong 
Published: February 2009

AbstractPolyvinyl acetate (PVAc)/titanium dioxide (TiO2) hybrid nanofibers were fabricated by combining sol–gel process with electrospinning technology, which consisted of PVAc as organic segment and TiO2 as inorganic part. The surface structures of the PVAc/TiO2 hybrid nanofibrous mats were examined using scanning electron microscopy (SEM). The surface morphology and bulk structures of single nanofiber were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was employed to analyze the chemical structures of the PVAc/TiO2 hybrid nanofibers. SEM scanning revealed that the fibrous structure was formed. AFM observations presented a significant difference in the morphology of the nanofibers before and after hybridization. It was observed from TEM images that some black streaks with various lengths distributed in a nanofiber. The FTIR analysis indicated the newly formed associated hydrogen bond because of the hybrid effect between PVAc and TiO2 sol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and thermal behavior of some brominated bismaleimides and polyaspartimides
Authors: Sava M. 
Published: February 2009

AbstractBrominated bismaleimides were synthesized by the reaction of brominated bisphenols with 3‐ or 4‐maleimidobenzoyl chloride. The reaction of these maleimides with various aromatic diamines yielded brominated polyaspartimides. The monomers and polymers were characterized by Fourier transformed infrared and proton nuclear magnetic resonance spectroscopy. Thermal behavior of these brominated polyaspartimides was studied and compared with that of related polyaspartimides having other substituents instead of bromine or other bridges in the bisphenolic segment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Electrorheological characteristics of solvent‐cast polypyrrole/clay nanocomposite
Authors: Park D. P. , Lim S. T. , Lim J. Y. , Choi H. J. , Choi S. B. 
Published: February 2009

AbstractA solvent‐casting method was applied to prepare intercalated polypyrrole (PPy)/organoclay nanocomposite for its electrorheological (ER) application under an applied electric field when dispersed in silicone oil. Soluble PPy was synthesized using sodium di(2‐ethylhexyl) sulfosuccinate (NaDEHS) as a doping agent at first, and its chemical structure and thermal property were examined using NMR and TGA, respectively. Insertion of the soluble PPy chain into an interlayer of the organoclay was confirmed by a X‐ray diffraction and its morphology was also examined by both SEM and TEM. Its ER property was examined under an applied electric field, regarding flow curve and universal yield stress. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study of VLE phase behavior and correlating the thermophysical properties of polymer solutions using a local composition‐based model
Authors: Pazuki G. R. , Taghikhani V. , Vossoughi M. 
Published: February 2009

AbstractIn this study, the recently proposed model by Pazuki et al., based on the local composition concept (LCC), has been used in correlating the vapor–liquid phase behavior of polymer solutions. Similar to the LCC models available in the literature, the proposed model has two combinatorial and residual terms to account for both entropic as well as enthalpic effects in solution. The Flory‐Huggins model has been considered as the combinatorial part of the proposed model, while the equation proposed by Pazuki et al. was considered as the residual term. The proposed model has been used in correlating the vapor–liquid phase behavior for a large number of polymer–solvent mixtures at different conditions. The results obtained from the proposed model have been compared with those obtained from the UNIQUAC‐FV model. The results showed that the proposed model can accurately correlate the VLE data for polymer solutions studied in this work. Also, the proposed model has been used to obtain the thermophysical properties such as density, viscosity, and excess enthalpy for these polymer solutions. The results in connection with the thermophysical properties obtained from the proposed model have been compared with those obtained from the Poly‐NRTL and the Poly‐Wilson models. The results showed that the proposed model can accurately correlate the properties of polymer solutions at various conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Development of novel tunable light scattering coating materials for fiber optic diffusers in photodynamic cancer therapy
Authors: Kostanski L. Kris , Pope Michael A. , Hrymak Andrew N. , Gallant Mark , Whittington William L. , Vesselov Leonid 
Published: February 2009

AbstractTo homogenize light emitted from fiber optic diffusers for photodynamic therapy (PDT), novel coating materials with tunable properties were designed. A class VI medical grade UV‐curable acrylic resin for biomedical applications was used for the polymer matrix, and titanium dioxide (TiO2) was added to the resin as a scattering agent. UV‐curability of coatings containing TiO2 was significantly influenced by the grade and surface treatment of the TiO2 studied. Despite using a free‐radical system without inert gas protection, all samples demonstrated considerable thermal postcuring. A novel TiO2 surface treatment methodology was developed based on unsaturated alkoxyorganosilanes combined with unsaturated carboxylic acids for compatibilizing TiO2 for use in the resin material studied. By adjusting the concentration of the surface‐modifying agent, the scattering efficiency and UV curability can be controlled by decreasing the effective particle size and enhancing the dispersibility of the powder filler within the resin. This modification will enable fine‐tuning of the effective size of TiO2 particles to the wavelength of laser light to be scattered to maximize scattering efficiency in photodynamic cancer therapy and possibly also in other forms of cancer treatment (interstitial laser hyperthermia or interstitial laser photocoagulation). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation of chitosan‐based thermosensitive hydrogels for drug delivery
Authors: Zhou Hui Yun , Chen Xi Guang , Kong Ming , Liu Cheng Sheng 
Published: February 2009

AbstractThe thermosensitive material that could be transformed into gel at 37°C was prepared from chitosan (dissolved in acetic acid/sodium acetate buffer solution) and a mixture of α‐ and β‐glycerophosphate (αβ‐GP). The thermosensitive characteristics, appearance, and structure of the hydrogel were all affected by the pH, ionic strength, and CS/αβ‐GP ratio. The optimal conditions for the preparation of a transparent CS‐αβ‐GP thermosensitive hydrogel were pH 4.6, ionic strength 0.15 mol/L, and a CS/αβ‐GP ratio of 8.8/1.2 (v/v). The hydrogel was stable for at least 3 months at 4°C. We believe that hydrogen bonding interactions between the NH (and CO) groups of chitosan and the OH groups of αβ‐GP play an important role during the process of sol‐to‐gel transition. The cumulative release of adriamycin from the CS‐αβ‐GP hydrogel, measured in PBS at pH 7.4, reached only 60 to 70% over 24 h, indicating that this material could be potentially used in a sustained drug delivery system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The water vapor sorption behavior of natural fibers
Authors: Hill Callum A. S. , Norton Andrew , Newman Gary 
Published: February 2009

AbstractThe water vapor sorption behavior of a range of natural fibers (jute, flax, coir, cotton, hemp, Sitka spruce) has been studied. The data were analyzed using the Hailwood Horrobin model for isotherm fitting and determination of monolayer moisture content. The Hailwood Horrobin model was found to provide good fits to the experimental data. The extent of hysteresis exhibited between the adsorption and desorption isotherms was dependent on fiber type studied and was larger with high lignin compared with low lignin content fibers. The area bounded by the hysteresis loop decreased as the isotherms were performed at progressively higher temperatures. This behavior is consistent with sorption interactions occurring with a glassy solid below the glass transition temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Insect chymotrypsins: chloromethyl ketone inactivation and substrate specificity relative to possible coevolutional adaptation of insects and plants
Authors: Lopes Adriana R. , Sato Paloma M. , Terra Walter R. 
Published: February 2009

AbstractInsect digestive chymotrypsins are present in a large variety of insect orders but their substrate specificity still remains unclear. Four insect chymotrypsins from 3 different insect orders (Dictyoptera, Coleoptera, and two Lepidoptera) were isolated using affinity chromatography. Enzymes presented molecular masses in the range of 20 to 31 kDa and pH optima in the range of 7.5 to 10.0. Kinetic characterization using different colorimetric and fluorescent substrates indicated that insect chymotrypsins differ from bovine chymotrypsin in their primary specificity toward small substrates (like N‐benzoyl‐L‐Tyr p‐nitroanilide) rather than on their preference for large substrates (exemplified by Succynil‐Ala‐Ala‐Pro‐Phe p‐nitroanilide). Chloromethyl ketones (TPCK, N‐ α‐tosyl‐L‐Phe chloromethyl ketone and Z‐GGF‐CK, N‐ carbobenzoxy‐Gly‐Gly‐Phe‐CK) inactivated all chymotrypsins tested. Inactivation rates follow apparent first‐order kinetics with variable second order rates (TPCK, 42 to 130 M−1 s−1; Z‐GGF‐CK, 150 to 450 M−1 s−1) that may be remarkably low for S. frugiperda chymotrypsin (TPCK, 6 M−1 s−1; Z‐GGF‐CK, 6.1 M−1 s−1). Homology modelling and sequence alignment showed that in lepidopteran chymotrypsins, differences in the amino acid residues in the neighborhood of the catalytic His 57 may affect its pKa value. This is proposed as the cause of the decrease in His 57 reactivity toward chloromethyl ketones. Such amino acid replacement in the active site is proposed to be an adaptation to the presence of dietary ketones. © 2009 Wiley Periodicals, Inc.
Optimal investment problem with stochastic interest rate and stochastic volatility: Maximizing a power utility
Authors: Li Jinzhu , Wu Rong 
Published: February 2009

AbstractIn this paper, we assume that an investor can invest his/her wealth in a bond and a stock. In our wealth model, the stochastic interest rate is described by a Cox–Ingersoll–Ross (CIR) model, and the volatility of the stock is proportional to another CIR process. We obtain a closed‐form expression of the optimal policy that maximizes a power utility. Moreover, a verification theorem without the usual Lipschitz assumptions is proved, and the relationships between the optimal policy and various parameters are given. Copyright © 2009 John Wiley & Sons, Ltd.
Inference Based on Kernel Estimates of the Relative Risk Function in Geographical Epidemiology
Authors: Hazelton Martin L. , Davies Tilman M. 
Published: February 2009

AbstractKernel smoothing is a popular approach to estimating relative risk surfaces from data on the locations of cases and controls in geographical epidemiology. The interpretation of such surfaces is facilitated by plotting of tolerance contours which highlight areas where the risk is sufficiently high to reject the null hypothesis of unit relative risk. Previously it has been recommended that these tolerance intervals be calculated using Monte Carlo randomization tests. We examine a computationally cheap alternative whereby the tolerance intervals are derived from asymptotic theory. We also examine the performance of global tests of hetereogeneous risk employing statistics based on kernel risk surfaces, paying particular attention to the choice of smoothing parameters on test power (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Re‐Formulating Non‐inferiority Trials as Superiority Trials: The Case of Binary Outcomes
Authors: Durkalski Valerie L. , Berger Vance W. 
Published: February 2009

AbstractNon‐inferiority trials are conducted for a variety of reasons including to show that a new treatment has a negligible reduction in efficacy or safety when compared to the current standard treatment, or a more complex setting of showing that a new treatment has a negligible reduction in efficacy when compared to the current standard yet is superior in terms of other treatment characteristics. The latter reason for conducting a non‐inferiority trial presents the challenge of deciding on a balance between a suitable reduction in efficacy, known as the non‐inferiority margin, in return for a gain in other important treatment characteristics/findings. It would be ideal to alleviate the dilemma on the choice of margin in this setting by reverting to a traditional superiority trial design where a single p ‐value for superiority of both the most important endpoint (efficacy) and the most important finding (treatment characteristic) is provided. We discuss how this can be done using the information‐preserving composite endpoint (IPCE) approach and consider binary outcome cases in which the combination of efficacy and treatment characteristics, but not one itself, paints a clear picture that the novel treatment is superior to the active control (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of Penalized Splines in Analyzing Neuronal Data
Authors: Maringwa John T. , Faes Christel , Geys Helena , Molenberghs Geert , Cadarso‐Suárez Carmen , Pardo‐Vázquez José L. , Leborán Víctor , Acunña Carlos 
Published: February 2009

AbstractNeuron experiments produce high‐dimensional data structures. Therefore, application of smoothing techniques in the analysis of neuronal data from electrophysiological experiments has received considerable attention of late. We investigate the use of penalized splines in the analysis of neuronal data. This is first illustrated when interested in the temporal trend of a single neuron. An approach to investigate the maximal firing rate, based on the penalizedspline model is proposed. Determination of the time of maximal firing rate is based on non‐linear optimization of the objective function with the corresponding confidence intervals constructed based on the first‐order derivative function. To distinguish between the curves from different experimental conditions in a moment‐by‐moment sense, bias adjusted simulation‐based simultaneous confidence bands leading to global inference in the time domain are constructed. The bands are an extension of the approach proposed by Ruppert et al. (2003). These methods are in a second step extended towards the analysis of a population of neurons via a marginal or population‐averaged model (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)