bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid‐phase microextraction for determining twelve orange flavour compounds in a model beverage emulsion
Authors: Mirhosseini Hamed , Tan Chin Ping , Yusof Salmah , Hamid Nazimah Sheikh Abdul 
Published: April 2008

AbstractSolid‐phase microextraction (SPME) coupled to gas chromatography has been applied for the headspace analysis (HS) of 12 target flavour compounds in a model orange beverage emulsion. The main volatile flavour compounds studied were: acetaldehyde, ethyl acetate, α‐pinene, ethyl butyrate, β‐pinene, myrcene, limonene, γ‐terpinene, octanal, decanal, linalool and citral (neral plus geranial). After screening the fibre type, the effect of other HS‐SPME variables such as adsorption temperature (25–55°C), extraction time (10–40 min), sample concentration (1–100% w/w), sample amount (5–10 g) and salt amount (0–30% w/w) were determined using a two‐level fractional factorial design (25−2) that was expanded further to a central composite design. It was found that an extraction process using a carboxen–polydimethylsiloxane fibre coating at 15ºC for 50 min with 5 g of diluted emulsion 1% (w/w) and 30% (w/w) of sodium chloride under stirring mode resulted in the highest HS extraction efficiency. For all volatile flavour compounds, the linearity values were accurate in the concentration ranges studied (r2 > 0.97). Average recoveries that ranged from 90.3 to 124.8% showed a good accuracy for the optimised method. The relative standard deviation for six replicates of all volatile flavour compounds was found to be less than 15%. For all volatile flavour compounds, the limit of detection ranged from 0.20 to 1.69 mg/L. Copyright © 2008 John Wiley & Sons, Ltd.
Evaluation of viability assays for anthocyanins in cultured cells
Authors: Elisia Ingrid , Popovich David G. , Hu Chun , Kitts David D. 
Published: April 2008

AbstractThe MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] assay is a widely accepted cytotoxicity assay which can produce inaccurate results due to possible interference with the antioxidant property of anthocyanins. Alternative methods to the MTT assay, such as BrdU (DNA‐based) and CellTiter‐Glo (ATP‐based) assays were evaluated to assess anthocyanin cytotoxicity, derived from blackberry in LNCaP, MCF‐7 and MDA‐MB‐453 cell lines. The standard cell counting method was the reference assay. Greater correlation of cell viability values following anthocyanin exposure was obtained from multiple cell lines with the alternative assays when compared with cell counting. MTT and cell counting results were not always correlated, albeit this was a function of cell type. In particular, poor correlations between cell counting and MTT procedures used to assess cytotoxicity of anthocyanins were observed in the MDA‐MB‐453 cell lines. Comparison of cytotoxicity derived from alternative assays and the MTT assays with the cell counting method was dependent on the assay procedure and the cell type. The LC50 of blackberry crude extract ranged from 0.4 to 9.4 mg/mL between assays and across all cell lines, whereas a semi‐purified anthocyanin extract was not cytotoxic. Cytotoxicity evaluation of polyphenolic‐rich extracts using BrdU and CellTiter‐Glo assays as alternatives to the MTT method is recommended. Copyright © 2008 John Wiley & Sons, Ltd.
Effect of coinitiator type on initiation efficiency of two‐component photoinitiator systems based on Eosin
Authors: Popielarz Roman , Vogt Otmar 
Published: April 2008

AbstractEffect of coinitiator structure on relative initiation efficiency of two‐component Eosin/coinitiator systems has been evaluated quantitatively in polymerization of poly(ethylene glycol) diacrylate as an example monomer. The initiation efficiency has been measured by the Fluorescence Probe Technique (FPT), using Eosin both as a photoinitiator component and as a fluorescent probe. A LED/fiber optic‐based measurement system has been developed and applied in this study. It has been found that from among 17 compounds tested, the following coinitiators form most efficient photoinitiating systems in combination with Eosin, when exposed to visible light: coinitiator, relative efficiency = triethanolamine, 1.0; 2,6‐diisopropyl‐N,N‐dimethylaniline, 0.70; 2‐benzyl‐2‐(dimethylamino)‐4′‐morpholinobutyrophenone (Irgacure 369), 0.91; carbon tetrabromide, 2.1; [4‐[(2‐hydroxytetradecyl)oxy]phenyl]phenyliodonium hexafluoroantimonate (SarCat 1012), 28. These relative efficiencies refer to the following component concentrations: [Eosin] = 8.6 × 10−4M, (0.05% by weight); [coinitiator] = 4.3 × 10−2M. The factors affecting the initiation efficiency of the systems studied are discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3519–3532, 2008
Hydrophilic graft modification of a commercial crystalline polyolefin
Authors: Shin Jihoon , Chang Andrew Y. , Brownell Lacie V. , Racoma Ira O. , Ozawa Coreen H. , Chung Ho‐Yong , Peng Shufu , Bae Chulsung 
Published: April 2008

AbstractHydroxy‐functionalized isotactic poly(1‐butene) was synthesized using transition metal‐catalyzed regioselective CH borylation at the side chain of the commercial polyolefin and subsequent oxidation of the boronic ester functionality. Functionalization up to ∼ 19 mol % of the termini of the ethyl side chain occurred without significant side reactions that could alter the polymer chain length. Esterification of the hydroxy group in the polymer with 2‐bromoisobutyl bromide generated a side chain‐functionalized polyolefin macroinitiator. Atom transfer radical polymerization of tert‐butyl acrylate from the macroinitiator produced a high molecular‐weight graft copolymer of the polyolefin, isotactic poly(1‐butene)‐graft‐poly(tert‐butyl acrylate) (PB‐g‐PtBA). Finally, the hydrolysis of the tert‐butoxy ester group of PB‐g‐PtBA created an amphiphilic polyolefin, isotactic poly(1‐butene)‐graft‐poly(acrylic acid), which contained a short carboxylic acid‐functionalized polymer block at the side chain. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3533–3545, 2008
Functionalization of surface‐grafted polymethylhydrosiloxane thin films with alkyl side chains
Authors: Thami Thierry , Nasr Gihane , Bestal Hanan , Van Der Lee Arie , Bresson Bruno 
Published: April 2008

AbstractThin films of crosslinked polymethylhydrosiloxane (PMHS) have been grafted on silica using the sol–gel process allowing further functionalization by effective quantitative hydrosilylation of SiH groups by olefins within the network. Postfunctionalization gives the polysiloxane network with n‐alkyl side chains. The PMHS coating was prepared by room temperature polycondensation of a mixture of methyldiethoxysilane HSiMe(OEt)2 monomer and triethoxysilane HSi(OEt)3 (TH) as crosslinker. The surface‐attached films are chemically stable and covalently bonded to the silica surface. Subsequently, films were functionalized without delamination. We showed by FTIR spectroscopy how the crosslinking ratio and the molecular size of the alkenes precursors influence the extent of the hydrosilylation reaction of SiH groups in the PMHS network. We have determined that quasi‐full olefin addition catalyzed by a platinum complex occurred within soft networks of less than 5% TH with 1‐alkenes CH2CH(CH2)n‐2CH3 of various alkyl chain lengths (n = 5, 11, 17). Powders of PMHS gel were also modified with 1‐alkenes by hydrosilylation. The SiH groups within the soft gel (5% crosslinked) were fully functionalized as shown by 29Si and 1H solid‐state NMR. The structure of functionalized polysiloxane with n‐octadecyl and n‐dodecyl side chains was studied by FTIR, wide angle X‐ray diffraction, and DSC showing crystallization of the long n‐alkyl chains in the network. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3546–3562, 2008
Real‐time FTIR monitoring of the mechanism of initiation of isobutylene polymerizations by epoxide/Lewis acid systems
Authors: Hayat Soytaş Serap , Puskas Judit E. , Kulbaba Kevin 
Published: April 2008

AbstractReal‐time Fourier Transformation Infrared (FTIR) spectroscopy with a fiber optic transmission probe (TR) was used to monitor the polymerization of isobutylene (IB) initiated by α‐methylstyrene epoxide (MSE) and 1,2‐epoxi‐2,4,4‐trimethylpentane (TMPO‐1) in conjunction with TiCl4 and BCl3. In the presence of an equimolar amount of BCl3, MSE and TMPO‐1 underwent ring opening via SN1 mechanism. In contrast to TiCl4‐coinitiated reactions, no oligoether formation via SN2 mechanism was observed. TMPO‐1 with excess BCl3 initiated IB polymerization, yielding a telechelic PIB carrying α‐primary OH and ω‐tertiary Cl functionalities with 70% initiator efficiency. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3611–3618, 2008
Impact of the clay organic modifier on the morphology of polymer–clay nanocomposites prepared by in situ free‐radical polymerization in emulsion
Authors: Greesh Nagi , Hartmann Patrice C. , Cloete Valeska , Sanderson Ronald D. 
Published: April 2008

AbstractPoly(styrene‐co‐butyl acrylate) copolymers were prepared by free‐radical random copolymerization of styrene and butyl acrylate in emulsion in the presence of 10% of surface‐modified sodium montmorillonite (Na‐MMT). The objective of this work was to evaluate the impact of the clay organic modifier in terms of its chemical structure, its degree of interaction within the clay galleries surface, and its ability to copolymerize with monomers, on the morphology and properties of the final nanocomposite prepared. Na‐MMT was modified using different organic modifiers, namely: sodium 1‐allyloxy‐2‐hydroxypropyl (Cops), 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS), N‐isopropylacrylamide (NIPA), and sodium 11‐methacryloyloxy‐undecan‐1‐yl sulfate (MET), respectively. The morphology and properties of the nanocomposites obtained were found to be dependant on the clay organic modifier. X‐ray diffraction (XRD) and transmission electron microscopy indicated that, nanocomposites at 10% clay loading with Cops‐, NIPA‐, and MET‐modified clays, yielded intercalated to partially exfoliated structures, whereas AMPS‐modified clay gave a nanocomposite with a fully exfoliated structure. All polymer–clay nanocomposites were found to be more thermally stable than neat poly(S‐co‐BA) as were determined by TGA. However, nanocomposites with intercalated structures exhibited greater thermal stability relative to fully exfoliated ones. Furthermore, nanocomposites with exfoliated structures exhibited higher storage moduli (GI) than partially exfoliated once, whereas intercalated structure showed the lowest GI values. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3619–3628, 2008
Thermogelling behaviors of poly(caprolactone‐b‐ethylene glycol‐b‐caprolactone) triblock copolymer in the presence of hyaluronic acid
Authors: Kim In Yong , Yoo Mi Kyong , Kim Bom Chol , Park In Young , Lee Hyun Chul , Cho Chong Su 
Published: April 2008

AbstractIn this article, we studied the effect of hyaluronic acid (HA) on thermogelation of poly(caprolactone‐b‐ethylene glycol‐b‐caprolactone) (PCL‐PEG‐PCL) aqueous solution designed as an injectable system for prevention of postsurgical tissue adhesion. The PCL‐PEG‐PCL triblock copolymers were simply synthesized by ring‐opening polymerization of ε‐caprolactone (CL) in the presence of PEG as a polymeric initiator. The synthesized copolymers were confirmed by proton nuclear magnetic resonance (1H‐NMR) spectroscopy. Possible interactions between HA and PCL‐PEG‐PCL triblock copolymers in the blend were evaluated by Fourier‐transform infrared spectroscopy (FTIR). The effect of HA on the micellization of PCL‐PEG‐PCL aqueous solution was investigated by dye solubilization method and electrophoretic lighting scattering (ELS) spectrophotometer. Also, the thermogelling behaviors of the PCL‐PEG‐PCL triblock copolymers in the presence of HA and their mechanism were investigated by test tube inverting method, 13C‐NMR, 1H‐NMR, Advanced Rheometic Expansion System (ARES), and differential scanning calorimetry (DSC). The PCL‐PEG‐PCL/HA blend aqueous solutions undergo the sol‐gel‐sol transition in response to an increase in temperature (10–60 °C) and the gelation of the PCL‐PEG‐PCL was rather accelerated by HA. Presumably, this accelerated gelation seems to arise from the attractive interactions between them and the effect of chain confinement in the micelle corona region. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3629–3637, 2008
Kinetics of dispersion polymerization: Effect of medium composition
Authors: Jiang Sheng , Sudol E. David , Dimonie Victoria L. , El‐Aasser Mohamed S. 
Published: April 2008

AbstractThe effect of the medium composition (monomer and solvent) on the kinetics of dispersion polymerization of methyl methacrylate (MMA) was studied via reaction calorimetry. It was found that increasing the monomer concentration increased the reaction rate; the exponent of the dependency of the initial reaction rate on the MMA concentration was found to be 0.93. Narrow particle size distributions were achieved at the lower monomer concentrations (0.24–0.81 mol/L) and a minimum size (2.45 μm) was found at an intermediate concentration (0.44 mol/L). The average molecular weight of the PMMA increased and the molecular weight distribution broadened with increasing monomer concentration. During a dispersion polymerization, the MMA concentration was found to decrease linearly with conversion in both phases, whereas the ratio of concentrations in the particles and continuous phase ([M]p/[M]c) remained constant (0.47) with partitioning favoring the continuous phase. The average number of free radicals per particle in MMA dispersion polymerization was estimated to be high from the nucleation stage onward (>5000). The increasing rate during the first ∼ 40% conversion was primarily caused by the increasing volume of the polymer particle phase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3638–3647, 2008
Synthesis of chiral micelles and nanoparticles from amino acid based monomers using RAFT polymerization
Authors: Skey Jared , O'reilly Rachel K. 
Published: April 2008

AbstractHomopolymers of tbutyl acrylate (PtBuA) and a monosubstituted acrylamide (PAM) having an amino acid moiety in the side chain, N‐acryloyl‐(L)‐phenylalanine methyl ester 1, have been synthesized by Reversible Addition‐Fragmentation Chain Transfer (RAFT) polymerization. Diblock copolymers of these homopolymers were also synthesized by chain extending PtBuA with monomer 1 and after modification, using simple acid deprotection chemistries of the acrylate block to afford a poly (acrylic acid) block, an optically active amphiphilic diblock copolymer was isolated. The optically active amphiphilic diblock copolymers, which contain chiral amino acid moieties within the hydrophobic segment, were then self‐assembled to afford spherical micelles which were subsequently crosslinked throughout the shell layer to afford robust chiral nanoparticles. The hydrodynamic diameters (Dh) of the block copolymer micelles and nanoparticles were measured by dynamic light scattering (DLS) and the dimensions of the nanoparticles were determined using tapping‐mode atomic force microscopy (AFM) and transmission electron microscopy (TEM). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3690–3702, 2008
An efficient solid‐state polycondensation method for synthesizing stereocomplexed poly(lactic acid)s with high molecular weight
Authors: Fukushima Kazuki , Kimura Yoshiharu 
Published: April 2008

AbstractSimultaneous solid‐state polycondensation (SSP) of the powdery prepolymers of poly(L‐lactic acid) (PLLA) and poly(D‐lactic acid) (PDLA) can produce entire stereocomplexed poly(lactic acid)s (sc‐PLA) with high molecular weight and can be an alternative synthetic route to sc‐PLA. Ordinary melt polycondensations of L‐ and D‐lactic acids gave the PLLA and PDLA prepolymers having medium molecular weight which were pulverized for blending in 1:1 ratio. The resultant powder blends were then subjected to SSP at 130–160 °C for 30 h under a reduced pressure of 0.5 Torr. Some of the products thus obtained attained a molecular weight (Mw) as high as 200 kDa, consisting of stereoblock copolymer of PLLA and PDLA. A small amount of the stereocomplex should be formed in the boundaries of the partially melted PLLA and PDLA where the hetero‐chain connection is induced to generate the blocky components. The resultant SSP products showed predominant stereocomplexation after their melt‐processing in the presence of the stereoblock components in spite of containing a small amount of racemic sequences in the homo‐chiral PLLA and PDLA chains. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3714–3722, 2008
Syntheses of multicyclic poly(ether sulfone)s from 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane and 4,4′‐bis(4‐chlorophenyl) sulfones
Authors: Kricheldorf Hans R. , Bornhorst Kirstin 
Published: April 2008

Abstract5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane (TTSBI) was polycondensed with 4,4′‐dichlorodiphenyl sulfone (DCDPS) or with 4,4′‐bis(4‐chlorophenyl sulfonyl) biphenyl (BCSBP) in DMSO. Concentration and feed ratio were optimized to avoid gelation and to obtain a maximum yield of multicyclic polyethers free of functional groups. Regardless of these reaction conditions, only low fractions of perfect multicycles were obtained from DCDPS apparently due to steric hindrance of ring closure. Under the same conditions high fractions of perfect multicycles were achieved with the longer and more flexible DCSBP. The reaction products were characterized by MALDI‐TOF mass spectrometry, 1H‐NMR spectroscopy viscosity, and DSC measurements. Relatively low glass transition temperatures (Tgs ≈ 160–175 °C) were found. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3732–3739, 2008
RAFT synthesis of amphiphilic (A‐ran‐B)‐b‐C diblock copolymers with tunable pH‐sensitivity
Authors: Hu Ying Qian , Kim Min Sang , Kim Bong Sup , Lee Doo Sung 
Published: April 2008

AbstractRAFT homopolymerization of 2‐(diisopropylamino)ethyl methacrylate (DPA) and 2‐(diethylamino)ethyl methacrylate (DEA) and their random copolymerization were investigated. The random copolymers of DPA‐ran‐DEA were synthesized and used as macro‐CTA to prepare poly(DPA‐ran‐DEA)‐b‐poly(N‐(2‐hydroxypropyl) methacrylamide) amphiphilic block copolymers. The 1H NMR and GPC measurements confirmed the successful synthesis of these copolymers. The potentiometric titration results showed that the pKb values of these copolymers were in the range of 6.7 ∼ 7.7 and linearly varied with the DPA/DEA composition, regardless of the block length of HPMA. The pH‐induced micellization in PBS solution was verified by fluorescence spectroscopy. The dynamic light scattering evaluation showed that the hydrodynamic diameters of these micelles are between 37 ∼ 43 nm © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3740–3748, 2008
Dispersibility of clay and crystallization kinetics for in situ polymerized PET/pristine and modified montmorillonite nanocomposites
Authors: Hwang Sung Yeon , Lee Wan Duk , Lim Jung Seop , Park Ki Hong , Im Seung Soon 
Published: April 2008

AbstractNanocomposite materials composed of poly (ethylene terephthalate) (PET) and montmorillonite (MMT) clays were prepared by in situ polymerization. Samples consisted of PET blended with various quantities of either pristine (Na+‐MMT) or organically modified MMT (A10‐MMT). The morphology and thermal and mechanical properties were evaluated for each sample. TEM micrographs, acquired at a 20 nm resolution, provide direct evidence of exfoliation of the clay particles into the PET matrix and show the effect of the alkyl‐modifier on clay dispersibility. The dispersion of PET/A10‐MMT was greater than that observed for the PET/Na+‐MMT nanocomposites. The greatest degree of exfoliation occurred for PET/A10‐MMT 0.5 wt %. However, PET/Na+‐MMT exhibited higher crystallization temperatures and rates suggesting that Na+‐MMT is a more efficient nucleating agent. Both mechanically and thermally, PET/A10‐MMT nanocomposites exhibited superior properties over pure PET. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1022–1035, 2008
Effects of compression cycles and precompression pressure on the repeatability of piezoresistivity for carbon black‐filled silicone rubber composite
Authors: Wang Luheng , Ding Tianhuai , Wang Peng 
Published: April 2008

AbstractWe studied the influences of the compression cycles and the precompression pressure on the piezoresistivity of carbon black‐filled silicone rubber composite. The experimental results show that if the load pressure is less than the maximum pressure in the precompression cycle, the repeatability of the piezoresistivity is improved with the increase of the compression cycles. Once the load pressure surpasses the maximum pressure in the precompression cycle, the piezoresistivity of the composite is changed distinctly. The experimental phenomena are explained and described qualitatively by analyzing the changes in the composite resistance under the zero pressure and the slippage of the molecule chain during the compression. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1050–1061, 2008
Crystal structure and morphologies of polypropylene homopolymer and propylene‐ethylene random copolymer: Effect of the substituted 1,3,5‐benzenetrisamides
Authors: Wang Jingbo , Dou Qiang , Chen Xianyi , Li Di 
Published: April 2008

AbstractFour different substituted 1,3,5‐benzenetrisamides were synthesized and two of them were reported for the first time. Their effects on the crystal structure and morphologies of the iPP homopolymer (PPH) and propylene‐ethylene random copolymers (PPR) were investigated. The results showed that they had versatile nucleating ability among the different crystal forms of PPH. The N,N′,N′′‐tris‐tert‐butyl‐1,3,5‐benzene‐tricarboxamide, N,N′,N′′‐tris‐cyclohexyl‐1,3,5‐benzene‐tricarboxamide, and N,N′,N′′‐tris‐isopropyl‐1,3,5‐benzene‐tricarboxamide suppressed the formation of detectable spherulites with the common α‐form of the PPH, as well as the N,N′,N′′‐n‐butyl‐1,3,5‐benzene‐tricarboxamide induced the spherulites of the β‐form. The combination of the ethylene segment and the nucleating agent facilitated the formation of the γ‐form. These trisamides had limited effects on the packing of the PPH segments but induced more compacted packing of the PPRs. The nucleation mechanism of such compounds was discussed for the first time, it was found that the nucleation ability of these compounds rooted in matching of their dimension of the b‐axis with dimension of the c‐axis of iPP, and their butterfly‐shape further enhanced it. The (001) face of the trisamides was in contact with the (010) face of iPP. This epitaxial crystallization led to preferential growth along the b‐axis, and the ethylene segment indeed enhanced this effect. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1067–1078, 2008
Where does all the helium that we use come from?
Authors: Manning David A. C. 
Published: April 2008

AbstractHelium occurs naturally in association with geological fluids and is regarded by economists as a mineral commodity. Commercially, helium is obtained as a by‐product from natural gas reservoirs that typically have concentrations of up to 1% He by volume (STP). Existing sources of helium within the USA are expected to decline in parallel with declining natural gas production. Huge reserves of helium occur in Algeria, Qatar and Russia, which are likely to dominate production for the next several decades. In this context, political and economic factors that affect hydrocarbon gas production may influence the availability and price of helium. Copyright © 2008 John Wiley & Sons, Ltd.