bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solution properties of dextran in water and in formamide
Authors: Antoniou Eleftheria , Tsianou Marina 
Published: January 2012

AbstractWe investigate here solution properties of the common polysaccharide dextran (with various molecular weight fractions: T70, T110, T500, and T2000) in aqueous and in formamide solutions at 20°C and 40°C, as obtained from viscosity measurements. Dextran behaves as a random coil in water and formamide solutions on the basis of the Mark‐Houwink‐Sakurada constant being in the range 0.5< α < 0.8 and the molecular weight dependence of the hydrodynamic coil radius,Rcoil∼MW1/2. Dextran segments interact more favorably with the formamide solvent molecules than with water, as attested by higher intrinsic viscosity,Rcoil, and hydrodynamic expansion factor αηvalues in formamide compared to aqueous solutions. This can be attributed to formamide offering more readily available sites (CO and NH3) to form hydrogen bonds with dextran. Apparently the stronger cohesive forces (reflected in higher surface tension σ and solubility parameter δ values) between water molecules make it harder for dextran to break them, thus the dextran coils swell less in this medium. As the temperature increases from 20°C to 40°C, dextran is driven toward theta conditions in both water and formamide solutions. Upon heating, the polymer segments interact less with the solvent molecules and adopt a less expanded conformation in the solution; the solvent quality decreases, and the coils contract. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Structure and properties enhancement in poly(phenylene sulfide) melt spun fibers. III. Effect of two zone drawing and annealing
Authors: Gulgunje Prabhakar , Bhat Gajanan , Spruiell Joseph 
Published: January 2012

AbstractThis article discusses the enhancement of structure and morphology of PPS fibers by annealing and two zone draw‐annealing. Also investigated is the comparison between fiber morphology and properties achieved by single zone draw‐annealing vis‐à‐vis extended annealing and two zone draw‐annealing. Annealing of undrawn as‐spun fibers yields tenacities around 4.5 gpd (grams/denier). It is shown that when compared with one zone drawing, two zone drawing improves PPS fibers' drawability and enhances the tensile properties significantly. Fibers spun from high molecular weight PPS resins, when drawn and annealed under optimum processing conditions during two zone draw‐annealing, possess tenacities around 6 gpd. A model for the fiber structure is proposed based on the morphological studies. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Improved method for dispersing clay in a monomer or bis(2‐hydroxyl ethyl terephthalate) before in situ polymerization of poly(ethylene terephthalate)/montmorillonite nanocomposites
Authors: Labde Rohan , Lofgren Elizabeth A. , Jabarin Saleh A. 
Published: January 2012

AbstractNatural montmorillonite (MMT) clay nanomaterials were successfully dispersed in poly(ethylene terephthalate) (PET) through two new and enhanced in situ polymerization methods. In the case of PET/MMT nanocomposites prepared through the esterification (ES) reaction clay‐addition method, unmodified MMT clays were dispersed in water and, then, the ethylene glycol monomer of PET before the preparation of bis(2‐hydroxyl ethyl) terephthalate (BHET) nanocomposites, which later underwent in situ polymerization. For nanocomposites prepared through the polycondensation (PC) reactor method, selected amounts of clay were dispersed in ethanol, with stirring inside the reactor. A portion of crushed BHET was then added to the PC reactor, and the combined mixture was stirred to achieve dispersion. The remaining BHET was added and mixed, the ethanol was evaporated by heating, and in situ polymerization was initiated. Morphological analysis by X‐ray diffraction and transmission electron microscopy confirmed the presence of exfoliated and intercalated clay structures in the nanocomposites prepared through both ES and PC clay‐addition methods. Nanocomposites containing lower concentrations of clay showed increases in the oxygen barrier properties in comparison to values obtained for the unmodified PET. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Mechanical properties of polypropylene blended with esterified and alkylated lignin
Authors: Maldhure Atul V. , Ekhe J. D. , Deenadayalan E. 
Published: January 2012

AbstractLignin does not show miscibility with commercial polyolefins. Therefore, industrial waste lignin was modified in two different ways and subsequently blended with commercial polypropylene (PP) up to 25 wt %. A Brabender electronic plasticorder was used for melt mixing at 190°C. The influence of different modifications on the mechanical properties and processing stability was studied for both polymer blends. The blends of PP and lignin modified (esterified) with maleic anhydride showed less deterioration in the mechanical properties compared to blends of PP and alkylated lignin with dichloroethane. Intermolecular interactions between the PP matrix and modified lignin were concluded on the basis of indicative values derived from various relevant theoretical models to the experimental data. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synergistic effect of phosphorus‐containing nanosponges on intumescent flame‐retardant polypropylene
Authors: Lai Xuejun , Zeng Xingrong , Li Hongqiang , Yin Changyu , Zhang Haili , Liao Feng 
Published: January 2012

AbstractA novel nanosponge (NS) was synthesized via the crosslinking of β‐cyclodextrin with epoxy resin. Subsequently, a phosphorus‐containing nanosponge (P–NS) was prepared by the absorbance of resorcinol bis(diphenyl phosphate) into the NS, and it was used as a synergistic agent of intumescent flame retardance in a polypropylene (PP)/melamine pyrophosphate/pentaerythritol composite. The synergistic effect between P–NS and the intumescent flame retardant (IFR) was investigated by thermogravimetry, limiting oxygen index (LOI) testing, vertical burning (UL‐94) testing, cone calorimeter testing, and scanning electron microscopy (SEM). The results show that P–NS significantly improved the flame retardancy of the PP/IFR composite. When 3.0 wt % P–NS replaced the same amount of IFR in the composite, the LOI value increased from 29.0 to 32.5%, the UL‐94 rating was enhanced from V‐1 to V‐0, and the peak heat release rate decreased substantially from 343 to 235 kW/m2. Simultaneously, the total heat release and mass loss rate decreased dramatically. Furthermore, the SEM results show that the quality of char formation of the PP/IFR/P–NS was superior to that of the PP/IFR composite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Maleic anhydride based copolymer dispersions for surface modification of polar substrates
Authors: Gunbas I. D. , Wouters M. E. L. , Hendrix M. M. R. M. , van Benthem R. A. T. M. , Koning C. E. , Noordover B. A. J. 
Published: January 2012

AbstractIn this article, we report the modification of poly(styrene‐alt‐maleic anhydride) (PSMA) with monofunctional amine‐terminated poly(dimethyl siloxane) (PDMS–NH2) by thermal imidization, followed by the preparation and characterization of a surfactant‐free artificial latex thereof and application of this latex onto cotton fabric. The imidization reaction was monitored by NMR and attenuated total reflection Fourier transform infrared (ATR–FTIR) spectroscopy. 1,2‐Cyclohexyldicarboxylic anhydride was chosen as a model compound for the PSMA copolymer; this allowed a more detailed characterization by NMR and ATR–FTIR spectroscopy. After the PSMA/PDMS–NH2 imidization reached completion, a fraction of the anhydrides were ammonolyzed. In this way, a self‐emulsifying latex with an average particle diameter of approximately 145 nm and a ζ potential of −56 mV was obtained. It was found that the PDMS‐modified PSMA latex in which 30 mol% of the initial amount of anhydride groups were previously imidized by using PDMS‐NH2 and a fraction of the anhydrides were ammonolyzed with 0.3 eq. of NH3 (PSMA30) was stable in the pH range 4–10. The water contact angle values of the latex‐coated cotton textile fabric indicated a hydrophobized surface, with a static contact angle of 135.7°± 1.2°. The washing studies with a standard soap solution of the cotton samples with or without crosslinker showed that the crosslinked PSMA30 offered a good coating durability to the cotton. This waterborne resin based on surfactant‐free latices displayed promising properties for coating applications and seemed to be very suitable for the hydrophobization of polar surfaces. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Catalytic performance and nanoclay effects on post‐solid‐state polyamidation: The case of polyamide 6,6 nanocomposites
Authors: Boussia A. C. , Konstantakopoulou M. O. , Vouyiouka S. N. , Papaspyrides C. D. 
Published: January 2012

AbstractThe catalytic performance of common additives was explored during the solid‐state postpolymerization (SSP) of polyamide 6,6 prepolymers. In particular, the influence of a phosphorous‐containing antioxidant and its combination with a nanofiller (clay) was examined during the SSP reaction at 200°C for times up to 4 h. The antioxidant, at a concentration of 1 phr, was found to strongly accelerate the SSP process by more than quintupling (435%) the reaction rate. The antioxidant–clay system (1 phr each) also catalyzed the SSP process and resulted in a near tripling (197%) of the reaction rate; this implied, however, a reduced single antioxidant catalytic performance. The latter was attributed to counteractions involving the diffusivity of polycondensation water versus clay hydrophilicity and to physical adsorption phenomena between the antioxidant and the clay. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Enhanced swelling properties of a novel sodium alginate‐based superabsorbent composites: NaAlg‐g‐poly(NaA‐co‐St)/APT
Authors: Shi Xiaoning , Wang Wenbo , Kang Yuru , Wang Aiqin 
Published: January 2012

AbstractA novel alginate‐based superabsorbent composite with enhanced swelling properties was synthesized by simultaneously grafted copolymerization partially neutralized acrylic acid (NaA), styrene (St) onto the sodium alginate (NaAlg) backbones in the presence of attapulgite (APT). The structure and morphology of the synthesized superabsorbent composites were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet‐visible (UV‐vis) spectra and Field emission scanning electron microscope (FESEM). Major factors affecting the swelling ratio according to Flory's theory were discussed. The superabsorbent composite synthesized under optimum reaction conditions exhibits the maximum swelling ratio of 587 g/g in distilled water and 73 g/g in 0.9 wt % NaCl solution. Compared with NaAlg‐g‐PNaA hydrogel, the simultaneous introduction of tiny amount of St and APT not only enhanced the swelling ratio but also increased the initial swelling rate. In addition, the effects of salt and pH medium on the swelling behaviors were investigated, and the results indicated that the composite showed smart swelling behavior in multivalent salt solution and better pH‐responsitivity in the pH 2.2 and 7.4 solutions, which makes it promising for drug delivery application. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis, spectroscopy, and electrochemical investigation of new conjugated polymers containing thiophene and 1,3,4‐thiadiazole in the main chain
Authors: Patil Prashant S. , Haram Nanda S. , Pal Ravindra R. , Periasamy N. , Wadgaonkar Prakash P. , Salunkhe Manikrao M. 
Published: January 2012

AbstractNovel photoluminescent donor–acceptor poly(p‐phenylenevinylene)‐type conjugated polymers containing thiophene and 1,3,4‐thiadiazole units in the main chain were synthesized from 2,5‐bis(5‐bromomethyl‐2‐thienyl)‐1,3,4‐thiadiazole and 1,3/1,4‐benzenedialdehyde by Wittig–Horner reaction. The synthesized polymers were characterized by the use of thermal analysis and spectroscopic (infrared, UV‐visible absorption, and photoluminescence) measurement. The resultant material exhibited bluish green, green, and orange fluorescence in their solution and thin film and solid forms, respectively. The redox property of the polymers has also been studied by cyclic voltammetry. The optical and electrochemical studies reveal that these novel polymers are new promising materials for the development of efficient polymer light‐emitting diodes. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Structure‐related behavior of hybrid organic–inorganic materials prepared in different synthesis conditions from Zr‐based NBBs and 3‐methacryloxypropyl trimethoxysilane
Authors: Di Maggio R. , Callone E. , Girardi F. , Dirè S. 
Published: January 2012

AbstractThe copolymerization of zirconium oxo‐clusters (Zr12) with 3‐methacryloxypropyl (trimethoxy)silane (MPTMS), using a Si/Zr molar ratio of 4, was investigated. The hybrid samples were prepared both with and without organosilane prehydrolysis. Differential scanning calorimetry (DSC), multinuclear liquid, and solid state NMR analyses and Fourier transform infrared (FTIR) spectroscopy were used to characterize the hybrid materials and study the influence of synthesis conditions on condensation and polymerization. The degree of condensation (DOC) of the silsesquioxane network and the polymerization yield are generally high. However, the organosilane prehydrolysis step leads to the reduction of the extent of phase interaction, thus favoring the phase separation between silica‐zirconia‐based domains. Dynamic mechanical spectroscopy (DMS) analyses were performed on the hybrid polymers obtained by means of the two synthetic pathways. The sample prepared without the organosilane prehydrolysis step presents a higher glass transition temperature (Tg) than the one with silane prehydrolysis. By heating above the Tg, the samples retain shape and size, due to the lack of viscous flow. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
New stabilizers for polystyrene based on 2‐thioacetic acid benzothiazol complexes
Authors: Yousif Emad , Salimon Jumat , Salih Nadia 
Published: January 2012

AbstractThe photostabilization of polystyrene (PS) films by 2‐thioacetic acid benzothiazol with Sn(II), Cd(II), Ni(II), Zn(II), and Cu(II) complexes was investigated. The PS films containing complexes of concentration 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl and hydroxyl indices with irradiation time. The changes in viscosimetric average molecular weight of PS with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (ϕcs) of these complexes in PS films was evaluated and found to range between 3.60 × 10−6 and 7.78 × 10−6. The results obtained showed that the rate of photostabilization of PS in the presence of the additive is in the following trend: Ni(L)2 > Cu(L)2 > Zn(L)2 > Cd(L)2 > Sn(L)2. According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among UV absorption, peroxide decomposer and radical scavenger for photostabilizer additive mechanisms were suggested. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Electrospinning of cellulose nanofibers from ionic liquids: The effect of different cosolvents
Authors: Härdelin Linda , Thunberg Johannes , Perzon Erik , Westman Gunnar , Walkenström Pernilla , Gatenholm Paul 
Published: January 2012

AbstractCellulose was electrospun with various concentrations of ionic liquid and cosolvent. Three different cosolvents were used in this study; dimethylacetamide (DMAc), dimethyl formamide (DMF), and dimethyl sulfoxide (DMSO). The cosolvents were added to modify the viscosity, electrical conductivity, and surface tension of the solutions. The solubility of cellulose in ionic liquids is highly affected by changes in solvent properties on the molecular level in the binary solvent systems. The difference in molecular structure of the cosolvents and the interactions between cosolvent and ionic liquid can explain the difference in dissolution power of the cosolvents. Scanning electron microscope (SEM) was used to characterize electrospun cellulose fibers. For the systems tested the importance of having a rather high viscosity and high surface tension, and some degree of shear thinning to produce fibers is shown. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of organic ligands with conjugated π‐bonds on the structure of iodine–α‐dextrin complexes
Authors: Yuldasheva Gulnara A. , Zhidomirov Georgii M. , Ilin Aleksandr I. 
Published: January 2012

AbstractUsing X‐ray data for iodine–α‐dextrin complexes and the results of quantum chemical ab initio restricted Hartree–Fock/3‐21G** level calculations, a model of drug active complex (AC) Armenicum with anti‐HIV action was proposed. It was suggested that the drug AC contains molecular iodine allocated inside of α‐dextrin helix and coordinated by lithium halogenides and a protein component of lymphocyte ribosomes. The electronic structure of I2 in this complex differs from its characteristics in complexes with organic ligands or the free I2. In the considered ACs, the molecular iodine displays acceptor (donor) properties toward the α‐dextrins (lithium halogenides). A mechanism of Armenicum anti‐HIV action is suggested. Under the influence of molecular iodine‐containing drug AC, the structure of HIV DNA is modified—it becomes more π‐donor‐active against proteins and peptide nucleotides of viral DNA form a stable complex with molecular iodine and lithium halogenides.
Scientific discovery as a combinatorial optimisation problem: How best to navigate the landscape of possible experiments?
Authors: Kell Douglas B. 
Published: January 2012

AbstractA considerable number of areas of bioscience, including gene and drug discovery, metabolic engineering for the biotechnological improvement of organisms, and the processes of natural and directed evolution, are best viewed in terms of a ‘landscape’ representing a large search space of possible solutions or experiments populated by a considerably smaller number of actual solutions that then emerge. This is what makes these problems ‘hard’, but as such these are to be seen as combinatorial optimisation problems that are best attacked by heuristic methods known from that field. Such landscapes, which may also represent or include multiple objectives, are effectively modelled in silico, with modern active learning algorithms such as those based on Darwinian evolution providing guidance, using existing knowledge, as to what is the ‘best’ experiment to do next. An awareness, and the application, of these methods can thereby enhance the scientific discovery process considerably. This analysis fits comfortably with an emerging epistemology that sees scientific reasoning, the search for solutions, and scientific discovery as Bayesian processes.
Effects of 6 months of endurance training on neutrophil functions to produce reactive oxygen species and mental states in male long‐distance runners
Authors: Kumae Takashi , Suzukawa Kazuhiro , Ishii Takashi 
Published: January 2012

ABSTRACTTo clarify changes of neutrophil functions, mental conditions and relationships among them, 19 male elite long‐distance runners participated in this study for 6 months. Examinations, with informed consent, were carried out once a month. According to the results of physical characteristics, it was thought that training intensity was reduced after the main race, Hakone‐Ekiden. Neutrophil functions were estimated by indices of reactive oxygen species production, determined by luminol‐ and lucigenin‐dependent chemiluminescence (LmCL and LgCL, respectively) and cytochrome c reduction methods. The peak times (PT) in LmCL and LgCL (LgPT) were most prolonged in January and December, respectively. The peak heights (PH) in LmCL (LmPH) were enhanced in February. Decreased levels of negative categories in the profile of mood state (POMS) questionnaire and the total mood state (TMS) of POMS were observed in February without significance. Correlation analysis using measured values revealed significant negative correlation between LmPH and negative categories in POMS; however, these correlations were possibly a mere appearance, caused by personal differences. After eliminating personal differences, LgPT correlated positively to depression (p < 0.05), anger (p < 0.05), fatigue (p < 0.01) and TMS (p < 0.05). These results suggest that the mean time from the recognition of foreign matter to the maximum production of superoxide from neutrophils is prolonged in the mentally suppressed conditions found under continuous physical training. Copyright © 2012 John Wiley & Sons, Ltd.
Quantitation of unbound sunitinib and its metabolite N‐desethyl sunitinib (SU12662) in human plasma by equilibrium dialysis and liquid chromatography–tandem mass spectrometry: application to a pharmacokinetic study
Authors: Rais Rana , Zhao Ming , He Ping , Xu Linping , Deeken John F. , Rudek Michelle A. 
Published: January 2012

ABSTRACTA rapid, selective, and sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous determination of unbound sunitinib and its active metabolite N‐desethyl sunitinib in plasma. Plasma and post‐dialysis buffer samples were extracted using a liquid–liquid extraction procedure with acetonitrile–n‐butylchloride (1:4, v/v). Chromatographic separation was achieved on a Waters X‐Terra® MS RP18 column with a mobile phase consisting of acetonitrile and water (60:40, v/v) containing formic acid (0.1%, v/v) using an isocratic run, at a flow‐rate of 0.2 mL/min. Analytes were detected by electrospray tandem mass spectrometry in the selective reaction monitoring mode. Linear calibration curves were generated over the ranges 0.1–100 and 0.02–5 ng/mL for sunitinib and 0.2–200 and 0.04–10 ng/mL for N‐desethyl sunitinib in plasma and in phosphate‐buffered solution, respectively. The values for both within‐day and between‐day precision and accuracy were well within the generally accepted criteria for analytical methods. The analytical range was sufficient to determine the unbound and total concentrations of both analytes. The method was applied for measurement unbound concentrations in addition to total concentrations of sunitinib and its metabolite in plasma of a cancer patient receiving 50 mg daily dose. Copyright © 2012 John Wiley & Sons, Ltd.
Pressure and Electrical Resistivity Measurements on Hot Expanded Metals: Comparisons with Quantum Molecular Dynamics Simulations and Average‐Atom Approaches
Authors: Clérouin J. , Starrett C. , Noiret P. , Renaudin P. , Blancard C. , Faussurier G. 
Published: January 2012

AbstractWe present experimental results on pressures and resistivities of expanded nickel and titanium at respective densities of 0.1 g/cm3 and 0.2 g/cm3, and in a range of temperature of 1‐3 eV that corresponds to the warm dense matter (WDM) regime. These data are used to benchmark different theoretical approaches. A comparison is presented between fully 3‐dimensional quantum molecular dynamics (QMD) methods, based on density functional theory, with average‐atom (AA) methods, that are essentially one dimensional. AA methods are used to identify interband transitions and photoionization thresholds. In this regime the evaluation of the thermodynamic properties as well as electrical properties is difficult due to the concurrence of density and thermal effects which directly drive the metal‐non‐metal transition. QMD simulations are also helpful to give a precise estimation of the temperature of experiments which is not directly accessible [1] (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)