bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quality control of Pulsatilla koreana based on the simultaneous determination of triterpenoidal saponins by HPLC‐ELSD and principal component analysis
Authors: Lee Ki Yong , Cho Young Woong , Park Junghyun , Lee Dong Young , Kim Seung Hyun , Kim Young Choong , Sung Sang Hyun 
Published: January 2010

AbstractIntroduction – Pulsatilla koreana Nakai, with triterpenoidal saponins as its main pharmacological effective compounds, is known to have several biological activities, including hypoglycaemic, antitumour, cognition‐enhancing, neuroprotective, cytotoxic and antiangiogenic activities. However, few analytical methods have been reported on the quality assessment of P. koreana roots.Obejective – To establish a high‐performance liquid chromatography coupled with evaporative light scattering detection for the simultaneous determination of five triterpenoidal saponins, including pulsatilloside E (1), pulsatilla saponin H (2), anemoside B4 (3), hederacolchiside E (4) and cussosaponin C (5) in P. koreana.Methodology – The chromatographic separation was performed on a Shiseido CapCell PAK C18 analytical column efficiently using gradient elution with acetonitrile and water.Results – All calibration curves showed excellent linear regressions (R2 > 0.9996) within the range of tested concentrations. The intra‐ and inter‐day variations were below 4.78% in terms of RSD. The recoveries were 94.82–102.97% with RSD of 0.27–3.92% for spiked P. koreana samples.Conclusion – The validated method was successfully used for the analysis of five saponins in P. koreana from different locations. Moreover, the different samples were clustered in accordance with contents of triterpenoidal saponins based on aglycon type by a principal component analysis. Copyright © 2010 John Wiley & Sons, Ltd.
Polypyrrole free‐standing electrodes sense temperature or current during reaction
Authors: Valero Laura , Arias‐Pardilla Joaquin , Smit Mascha , Cauich‐Rodríguez Juan , Otero Toribio F 
Published: January 2010

AbstractThe electrochemical activity of self‐supported thick (70 µm) polypyrrole films electrogenerated in a mixed electrolyte of dodecylbenzenesulfonic acid and LiClO4 was studied in aqueous solutions of LiClO4. This material inhibits hydrogen evolution up to cathodic potentials of −3.0 V versus Ag/AgCl. During oxidation or reduction reactions under galvanostatic conditions, the electrical energy consumed for a constant charge is a function of either the working temperature or the flowing current. As a consequence any electrochemical device, moreover artificial muscles, constructed with reactive conducting polymers is expected to work simultaneously as a sensor of the working temperature. Copyright © 2010 Society of Chemical Industry
Preparation and characterization of monodisperse CdS quantum dot‐polymer microspheres
Authors: Shao Qian , Yang Chengli , Jiang Lingzhi , He Jie , Li Shijie , Jiang Biwang 
Published: January 2010

AbstractA novel and effective method for the preparation of monodisperse CdS quantum dot‐polymer microspheres was proposed. The monodisperse hollow polymer microspheres were firstly swelled in chloroform. Then, the reaction precursor composed of CdO and sulfur, was impregnated into the hollow polymer microspheres. Subsequently, the CdS quantum dots were synthesized directly within the polymer microspheres by thermal decomposition. The morphology, structure, and fluorescence properties of CdS quantum dot‐polymer microspheres were studied by scanning electron microscope, transmission electron microscope, fluorescence microscope, and flow cytometry. The results indicate that the fluorescent CdS quantum dots are successfully synthesized in the monodisperse hollow polymer microspeheres, which provide very strong fluorescence intensity, and offer excellent photostability due to the compact structure of the polymer matrix. These CdS quantum dot‐polymer microspheres have potential applications in biotechnology and biomedicine. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 751–755, 2010
Poly(terthiophene)s from copolymer precursors via solid‐state oxidative conversion
Authors: Kumar Arvind , Invernale Michael A. , Jang Sung‐Yeon , Sotzing Gregory A. 
Published: January 2010

AbstractHerein, we report the synthesis of conducting poly (terthiophene)s using a side chain precursor polymer approach. Random copolymers were prepared by ring opening metathesis polymerization of two norbornylene monomers, one containing a pendant terthiophene group and the other containing a pendant acetate group. Solid‐state oxidative conversion of the terthiophene units was used to produce conductive polymers. Oxidative solid‐state conversion was successful for copolymers containing as little as 1 mol % of terthiophene comonomer. The electrical and optical properties of CPs were studied as a function of the amount of electroactive moiety, terthiophene (3T), present in the copolymer. The CPs were found to have conductivity varying between 10−1 and 10−4 S/cm depending on the precursor copolymer compositions. The CPs obtained from all precursors had no significant difference in their energy gaps and showed blue to orange color transitions when switching from the oxidized to the neutral states, respectively. The absorbance intensity at 426 nm for poly(3T) from the precursors fits the Beer–Lambert law corresponding to the range of initial 3T content in the precursor copolymer composition (from 1 to 100 mol %). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 756–763, 2010
Thermoresponsive terpolymers based on methacrylate monomers: Effect of architecture and composition
Authors: Ward Mark A. , Georgiou Theoni K. 
Published: January 2010

AbstractA series of amphiphilic thermoresponsive copolymers was synthesized by group transfer polymerization. Seven copolymers were prepared based on the nonionic hydrophobic n‐butyl methacrylate (BuMA), the ionizable hydrophilic and thermoresponsive 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and the nonionic hydrophilic poly(ethylene glycol)methyl methacrylate (PEGMA). In particular, one diblock copolymer and six tricomponent copolymers of different architectures and compositions, one random and five triblock copolymers, were synthesized. The polymers and their precursors were characterized in terms of their molecular weight and composition using gel permeation chromatography and proton nuclear magnetic resonance spectroscopy, respectively. Aqueous solutions of the polymers were studied by turbidimetry, hydrogen ion titration, and light scattering to determine their cloud points, pKas, and hydrodynamic diameters and investigate the effect of the polymers' composition and architecture. The thermoresponsive behavior of the copolymers was also studied. By increasing the temperature, all polymer solutions became more viscous, but only one polymer, the one with the highest content of the hydrophobic BuMA, formed a stable physical gel. Interestingly, the thermoresponsive behavior of these triblock copolymers was affected not only by the terpolymers' composition but also by the terpolymers' architecture. These findings can facilitate the design and engineering of injectable copolymers for tissue engineering that could enable the in situ formation of physical gels at body temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 775–783, 2010
Synthesis and properties of high‐molecular‐weight stereo di‐block polylactides with nonequivalent D/L ratios
Authors: Hirata Masayuki , Kobayashi Kaori , Kimura Yoshiharu 
Published: January 2010

AbstractDi‐stereoblock polylactides (di‐sb‐PLA: PLLA‐b‐PDLA) having high molecular weight (Mn > 100 kDa) were successfully synthesized by two‐step ring‐opening polymerization (ROP) of L‐ and D‐lactides using tin(2‐ethylhexanoate) as a catalyst. By optimizing the polymerization conditions, the block sequences were well regulated at non‐equivalent feed ratios of PLLA and PDLA. This synthetic method consisted of three stages: (1) polymerization of either L‐ or D‐lactide to obtain a PLLA or PDLA prepolymer with a molecular weight less than 50 kDa, (2) purification of the obtained prepolymer to remove residual lactide, and (3) polymerization of the enantiomeric lactide in the presence of the purified prepolymer. Their 13C and 31P NMR spectra of the resultant di‐sb‐PLAs strongly supported their di‐stereo block structure. These di‐sb‐PLAs, having weight‐average molecular weights higher than 150 kDa, were fabricated into polymer films by solution casting and showed exclusive stereocomplexation. The thermomechanical analysis of the films revealed that their heat deformation temperature was limited probably because of their low crystallinity owing to the non‐equivalent PLLA/PDLA ratio. The blend systems of the di‐sb‐PLAs having complementary stereo‐sequences (the one with a long PLLA block and the other with long PDLA block) were also prepared and characterized to enhance the sc crystallinity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 794–801, 2010
Three‐component polyaddition of diamines, carbon disulfide, and diacrylates in water
Authors: Nagai Daisuke , Imazeki Tsutomu , Morinaga Hisatoyo , Oku Hiroyuki , Kasuya Ken‐Ichi 
Published: January 2010

AbstractThe three‐component polyaddition of diamines, carbon disulfide (CS2), and diacrylates in water was successfully achieved without the use of a surfactant or catalyst. Appropriate reaction conditions (i.e., reaction temperature, reaction time, and CS2 feed) enabled the polyaddition of 1,3‐di‐4‐piperidylpropane (1a), CS2, and 1,6‐hexanediol diacrylate (2a) to afford the corresponding poly(dithiourethane‐amine) containing 83% of dithiourethane units in 84% yield. Polyaddition of other monomers also proceeded under the optimum conditions to afford various poly(dithiourethane‐amine)s. Unsuccessful results for polyaddition in organic solvents such as toluene, tetrahydrofuran, and N,N‐dimethylformamide revealed that the polyaddition is accelerated in water. The obtained poly(dithiourethane‐amine)s adsorbed Au (III) efficiently under acidic conditions, due to the strong interaction of the thiocarbonyl sulfur in the dithiourethane unit with Au (III). The poly(dithiourethane‐amine)s also showed selective adsorption for Au (III) from a mixture of metal ions [Au (III), Fe (III), Mn (II), and Zn (II)], which indicates their potential utilization for the collection of gold. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 845–851, 2010
Quinoline‐containing networks from enone and aldehyde triglyceride derivatives
Authors: Montero de Espinosa Lucas , Ronda Juan C. , Galià Marina , Cádiz Virginia 
Published: January 2010

AbstractThe crosslinking reaction of a triglyceride derivative containing α,β‐unsaturated ketones with diaminodiphenylmethane via aza‐Michael addition has been extensively studied. First, a model study with monofunctional compounds showed that the conjugated addition product undergoes a series of transformations leading to formation of a substituted quinoline. The proposed reaction pathway is presented as a variation of the Skraup‐Doebner‐Von Miller quinoline synthesis. The presence of quinolines as crosslinking points in the cured materials has been proved by means of different characterization techniques, and the properties derived from this aromatization process have been described. This new crosslinking approach has been successfully applied to an aldehyde‐containing triglyceride to obtain quinoline‐containing thermosets. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 869–878, 2010
Preparation, characterization, and electrical properties of dual‐emissive Langmuir‐Blodgett films of some europium‐substituted polyoxometalates and a platinum polyyne polymer
Authors: Liu Li , Chen Ming , Yang Jun , Liu Shi‐Zhong , Du Zu‐Liang , Wong Wai‐Yeung 
Published: January 2010

AbstractA new series of organometallic/inorganic composite Langmuir‐Blodgett (LB) films consisting of a rigid‐rod polyplatinyne polymer coordinated with 2,7‐bis(buta‐1,3‐diynyl)‐9,9‐dihexylfluorene (denoted as PtP) as the π‐conjugated organometallic molecule, an europium‐substituted polyoxometalate (POM; POM = Na9EuW10O36, K13[Eu(SiW11O39)2] and K5[Eu(SiW11O39)(H2O)2]) as the inorganic component, and an amphiphilic behenic acid (BA) as the auxiliary film‐forming agent were prepared. Structural and photophysical characterization of these LB films were achieved by π–A isotherms, absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low‐angle X‐ray diffraction. Our experimental results indicate that stable, well‐defined, and well‐organized Langmuir and LB films are formed in pure water and POM subphases, and the presence of Eu‐based POM in the subphase causes an area expansion. It is proposed that a lamellar layered structure exists for the PtP/BA/POM LB film in which the POM and PtP molecules can lay down with the interfacial planes. Luminescence spectra of the prepared hybrid LB films show that near‐white emission spectra can be obtained due to the dual‐emissive nature of the mixed PtP/POM blends. These Pt‐polyyne‐based LB films displayed interesting electric conductivity behavior. Among them, PtP/BA/POM 13‐layer films showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between −1 and 7 V. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 879–888, 2010
Influence of structural features on the self‐assembly of short ionic oligopeptides
Authors: Desii Andrea , Chiellini Federica , Duce Celia , Ghezzi Lisa , Monti Susanna , Tiné Maria R. , Solaro Roberto 
Published: January 2010

AbstractWe investigated the self‐aggregation of 12 short ionic oligopeptides constituted by 4–7 amino acid residues to establish useful structure–property relationships that might be exploited in the biomedical field by using the concept of molecular Lego. We show that the critical aggregation concentration (CAC) of tetrapeptides decreases with increasing hydrophobicity of neutral residues. Additionally, the dependence of the CAC of isomeric oligopeptides on the distribution of amino acid residues confirms the high tendency to self‐organization of molecules with alternating ionic and neutral residues. Indeed, atomic force microscopy (AFM) images recorded on oligopeptide solutions above the CAC show the presence of either fibrillar or spherical aggregates depending on oligopeptide structure and concentration, steric hindrance, solution pH, and time. The potential of the investigated oligopeptides in tissue engineering applications is supported by their in vitro cytocompatibility. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 889–897, 2010
Chiral arylnickel complexes as highly active initiators for screw‐sense selective living polymerization of 1,2‐diisocyanobenzenes
Authors: Yamada Tetsuya , Noguchi Hiroyoshi , Nagata Yuuya , Suginome Michinori 
Published: January 2010

AbstractOptically active chiral organonickel complexes served as efficient chiral initiators for living aromatizing polymerization of 1,2‐diisocyanobenzene derivatives, which afford optically active helical poly(quinoxaline‐2,3‐diyl)s up to 84% s.e. (screw‐sense excess). In comparison with asymmetric polymerization with the corresponding organopalladium initiators, the nickel initiators show a much greater polymerization rate, while the selectivity remains high. The organonickel initiators can be generated in situ from nickel(0) precursors with the corresponding enantiopure (S,S)‐2‐(4,5‐diphenylimidazolin‐2‐yl)phenyl chloride, leading to the convenient synthesis of highly stereo‐controlled poly(quinoxaline‐2,3‐diyl)s. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 898–904, 2010
Enhanced mobility and increased gas sorption capacity in thin film and nanoconduit confined polymers
Authors: Killgore Jason P. , Kocherlakota Lakshmi S. , Overney René M. 
Published: January 2010

AbstractPoly(tert butyl acrylate) (PTBA) is found to exhibit enhanced mobility when spun cast into thin films or impregnated into cylindrical anodic aluminum oxide (AAO) nanoscale pores. In a thin film configuration, the glass transition temperature of 20 nm thick PTBA is found to decrease almost 20 °C compared to the bulk. Consistent with this mobility increase, an increased volume fraction of interphase polymer leads to at least a 2.4 times viscosity reduction when PTBA is impregnated in 100 nm pores versus 200 nm pores. Such increases in mobility result in a 15‐fold increase in CO2 permeability for an AAO confined geometry compared to a bulk film. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 434–441, 2010
Effect of molecular weight and substrate on silicone segregation from UV resin at plasma polymerized mold interface
Authors: Zhou Wen Xiu , Yan Ye Hai , Pan Xiaoyong , Xu Rong , Chan‐Park Mary B. 
Published: January 2010

AbstractPristine‐, poly(octafluorotoluene)‐ (POFT), and polyacetylene (PAc)‐coated Si wafers were used as substrates for the study of segregation of silicone diacrylate (SA) from a formulation containing other oligomeric and monomeric acrylates. POFT and PAc were microwave plasma polymerized on the Si wafers. Three SAs with molecular weights ranging from 700 to 6000 Da were synthesized and characterized. Formulations with 2 wt % SA were ultraviolet cured on the silicon wafers. The surface composition of formulation‐substrate side of the cured film was analyzed with X‐ray photoelectron spectroscopy, and the depth profile was analyzed with time of flight‐secondary ion mass spectrometry. The analysis results indicated that SA aggregated on all three types of Si surfaces. However, SA segregation is highest on the low surface energy POFT‐coated Si substrate, and low‐molecular‐weight SA is favorable to the segregation. For high‐molecular‐weight SA, the different Si substrates do not affect the degree of aggregation at the formulation‐substrate interface. The observed SA aggregation trend can be predicted by the Gibbs‐adsorption equation correlated to the resin surface tension and contact angle on substrates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 442–450, 2010
Enhanced dielectric response in P(VDF‐TrFE) based all‐organic nanocomposites
Authors: Wang Jingwen , Wang YE , Li Shuqin , Xiao Jun 
Published: January 2010

AbstractA nanocomposite with enhanced dielectric response is developed using poly(vinylidene fluoride‐trifluoroethylene) [P(VDF‐TrFE)] as matrix and Chemically modified high dielectric constant organic semiconductor—copper phthalocyanine oligomer (CuPc)—as filler. Transmission electron microscope (TEM)‐observed morphologies reveal that in the nanocomposite the average size of CuPc particles is about 25 nm [1/24 of that of CuPc in physical blend of P(VDF‐TrFE) and CuPc]. The hot‐press nanocomposite film with 15 wt % CuPc can realize a dielectric constant of 540 at 100 Hz. The enhanced dielectric response in the nanocomposite demonstrates the significance of the interface effect in raising the material responses far beyond that expected by simple mixing rules when there is a large dielectric contrast between the polymer matrix and the dielectric filler in the composite. It is also interesting to note that at high frequencies (such as 100 MHz) the nanocomposite has a dielectric constant of ∼100 and this value is comparable to those of current materials used in microwave applications. At 105 °C that is near the ferroelectric‐to‐paraelectric phase transition temperature of the P(VDF‐TrFE) ferroelectric, a much higher dielectric constant (about 1200 at 100 Hz) is obtained. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 490–495, 2010
One‐Step Plasma Deposition of Platinum Containing Nanocomposite Coatings
Authors: Dilonardo Elena , Milella Antonella , Palumbo Fabio , Capitani Giancarlo , d'Agostino Riccardo , Fracassi Francesco 
Published: January 2010

AbstractIn this paper a single step process for the synthesis of composite thin films made of platinum nanoclusters embedded in a porous hydrocarbon matrix is proposed. The process consists of a simultaneous plasma enhanced‐chemical vapour deposition of ethylene and sputtering of a platinum target. Films were characterized by means of Fourier transform‐infrared spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Optical emission spectroscopy was used to investigate the plasma phase and to find correlations with the metal content of the film. The effect of radio frequency power, deposition time, and ethylene flow rate on the chemical composition and structure of the film is presented. Results show that the platinum content in the film can be controlled by tuning the power delivered to the plasma and the monomer flow rate, and that the metal aggregates in crystalline nanoclusters uniformly distributed in the material. Film morphology is characterized by columnar structures of variable diameter and orientation depending on the deposition conditions.magnified image
Measurement of pesticide residues in peppers by near‐infrared reflectance spectroscopy
Authors: Sánchez María‐Teresa , Flores‐Rojas Katherine , Guerrero José Emilio , Garrido‐Varo Ana , Pérez‐Marín Dolores 
Published: January 2010

AbstractBACKGROUND: Peppers are a frequent object of food safety alerts in various member states of the European Union owing to the presence in some batches of unauthorised pesticide residues. This study assessed the viability of near‐infrared reflectance spectroscopy (NIRS) for the measurement of pesticide residues in peppers. Commercially available spectrophotometers using different sample‐presentation methods were evaluated for this purpose: a diode‐array spectrometer for intact raw peppers and two scanning monochromators fitted with different sample‐presentation accessories (transport and spinning modules) for crushed peppers and for dry extract system for infrared analysis (DESIR), respectively.RESULTS: Models developed using partial least squares–discriminant analysis (PLS2‐DA) correctly classified between 62 and 68% of samples by presence/absence of pesticides, depending on the instrument used. At model validation, the highest percentage of correctly classified samples—75 and 82% for pesticide‐free and pesticide‐containing samples respectively—were obtained for intact peppers using the diode‐array spectrometer.CONCLUSION: The results obtained confirmed that NIRS technology may be used to provide swift, non‐destructive preliminary screening for pesticide residues; suspect samples may then be analysed by other confirmatory analytical methods. Copyright © 2010 Society of Chemical Industry