bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase state of polyelectrolyte complexes based on blends of acrylic copolymers
Authors: Kiseleva T. I. , Shandryuk G.A. , Khasbiullin R. R. , Shcherbina A. A. , Chalykh A. E. , Feldstein M. M. 
Published: July 2011

AbstractThe phase state of polyelectrolyte blends based on acrylic copolymers was investigated with differential scanning calorimetry, transmission electron microscopy (TEM), and wedge microinterferometry as a function of the blend composition and ionization of polymer functional groups. A copolymer of N,N‐dimethylaminoethyl methacrylate with methyl methacrylate and butyl methacrylate was used as a polybase, a copolymer of methacrylic acid and ethyl acrylate was employed as a polyacid, and the optional plasticizer was triethyl citrate. A correlation was established between an earlier described mechanism of molecular interaction and the behavior of the glass‐transition temperature (Tg) of the polymer blends. The Tg values of the polyelectrolyte complexes in the gel phase were always higher than Tg in the sol phase. This fact implies that intermolecular cohesion dominated the free volume in the stoichiometric polyelectrolyte complexes formed in the gel phase, whereas nonstoichiometric complexes formed in the sol phase were characterized with the predominant contribution of free volume. TEM and interferograms of polyelectrolyte blends showed the signs of anisotropic ordered supramolecular structure formation. A phase‐state diagram of the polyelectrolyte blends was constructed. The stoichiometric polyelectrolyte complex was immiscible with parent polymers, forming a separate phase that became melted at elevation of temperature because of complex dissociation. Polyelectrolyte miscibility was supposed to result rather from the chemical reaction of the complex formation than from interdiffusion of the polymer components along the gradient of their concentration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A comprehensive single‐particle model for solid‐state polymerization of poly(L‐lactic acid)
Authors: Katiyar Vimal , Shaama Mallikarjun Sharada , Nanavati Hemant 
Published: July 2011

AbstractWe propose here, a comprehensive model for the solid‐state polymerization (SSP) of a low to moderate molecular weight (MW) prepolymer of lactic acid, to produce high MW poly(L‐lactic acid) (PLLA). The reactions are rationally assumed to occur only in the amorphous region, and effective concentrations of end groups, vary with crystalinity, Xc, during SSP. We estimate byproduct diffusivities, D, using free volume theory. The effects of various parameters on the SSP of PLLA prepolymer have been examined with respect to the optimum MW, Xc and D. We introduce self‐consistently, scaling factors of ∼ 0.27, in the experimental procedure, to determine via 19F‐NMR, concentrations of the end groups, after converting them to fluorinated ester groups. The relevant reaction rate constants are obtained by fitting to early time data from representative SSP experiments at 150°C, under high vacuum, on PLLA prepolymer powder (i.e., spherical geometry) of number average MW, Mn0 ∼ 10,200 Da, which attains Mn ∼ 150,000 Da, via SSP. The subsequent successful comparison of the model predictions with experimental data throughout the entire SSP duration indicates that the model is comprehensive and accounts for all the relevant phenomena occurring during the SSP to synthesize high MW PLLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Partition coefficients for a mixture of two lubricant oligomers
Authors: Kanniah Vinod , Forbus T. Reg , Parker Stephanie , Grulke Eric A. 
Published: July 2011

AbstractUniversal base oils that remain pourable over wide temperature ranges would have important advantages for lubrication applications. The model system used in this project was a poly(α‐olefin) synthetic base oil modified with polydimethylsiloxane (PDMS) to lower the pour‐point temperature. Although the blend was miscible at room temperature, phase separation occurred at temperatures lower than 258 K. Partition coefficients of such nonideal oligomer mixtures can (1) help define operating temperature ranges and (2) provide a basis for designing molecular weight distributions of each lubricant that control or prevent phase separation. The poly(α‐olefin) base oil family is branched oligomers with two to five n‐mers at levels greater than 1 wt %, whereas PDMS additives are linear oligomers having between 10 and 50 sequential n‐mers at levels greater than 0.5 wt %. In this study, Fourier transform infrared measurements of the poly(α‐olefin) and PDMS compositions in each phase provided an overall material balance. Poly(α‐olefin) oligomers were detected with size exclusion chromatography with a differential refractive‐index detector, and PDMS oligomers were detected with matrix‐assisted laser desorption/ionization–time‐of‐flight mass spectrometry. The best sets of measurements for the individual oligomers in each phase were selected by minimization of the overall material balance errors. For both oligomers, components with high molecular weights were preferentially excluded from the phase rich in the other polymer and were relatively independent of temperature. The partition coefficients of poly(α‐olefin) components increased with increasing oligomer length, whereas the partition coefficients of the PDMS components decreased with increasing oligomer length. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis of a chiral stationary phase with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] by surface‐initiated atom transfer radical polymerization and its chiral resolution efficiency
Authors: Yang Ji‐Hoon , Choi Seong‐Ho 
Published: July 2011

AbstractA chiral stationary phase (CSP) with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] was synthesized by the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)‐6‐acrylate after the SI‐ATRP of styrene on the surface of silicon dioxide supports in pyridine. The successful preparation of the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] was confirmed via Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X‐ray photoelectron spectroscopy, elemental analysis, and thermal analysis. The applicability for the chiral resolution of the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐diphenylcarbamate)] was evaluated with high‐performance liquid chromatography with 10 racemates under various mobile phases of hexane/alcohol, hexane/tetrahydrofuran (THF), and hexane/chloroform. The results show that the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐diphenylcarbamate)] could be used in THF and chloroform as eluents. The chiral resolutions of the commercial Chiracel OD, the CSP with cellulose 2,3‐bis(3,5‐dimethylphenylcarabmate), and the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] prepared by SI‐ATRP were examined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Diffusion of levofloxacin mesylate in agarose hydrogels monitored by a refractive‐index method
Authors: Dai Hongjun , Wu Junjie , Wang Yongxin , Tan Shuaixia , Liang Songmiao , Jiang Bin , Zhao Ning , Xu Jian 
Published: July 2011

AbstractThe diffusion of levofloxacin mesylate (MSALVFX) within agarose hydrogels was investigated by an improved refractive‐index method. The diffusion coefficient of MSALVFX in infinite dilution (D0) was obtained as 4.01 × 10−6 cm2/s (25°C) through extrapolation according to Kohlrausch's law. The diffusion behavior of MSALVFX under conditions of different solute concentrations, polymer volume fractions, and temperatures was studied in detail. In the considered range of agarose concentrations (0.5–2.5%, w/w), the ratio of Dg to D0 (where Dg is the effective diffusion coefficient of MSALVFX in the agarose hydrogel) decreased from 0.938 to 0.835 because of the retardance effect of agarose fiber. Furthermore, the experimental data were analyzed with the Amsden, Clague and Philips, and Ogston models, and the data fit the Amsden model best. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation and crystallization behavior of poly(vinylidene fluoride‐ter‐chlorotrifluoroethylene‐ ter‐trifluoroethylene)
Authors: Li Hengfeng , Tan Kaiyuan , Hao Zeming , He Guowen 
Published: July 2011

AbstractSeveral poly(vinylidene fluoride‐ter‐chlorotrifluoroethylene‐ter‐trifluoroethylene) terpolymers, including 68 mol % vinylidene fluoride, were prepared by the partial reduction of chlorine in poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) copolymers. The terpolymers were then allowed to crystallize under two sets of conditions: (1) crystallized from solution (in N,N‐dimethylformamide) at 35°C for 108 h and (2) annealed at temperatures 5°C below their respective melting points for 11 h. The effect of the chlorotrifluoroethylene (CTFE) content and crystallization conditions on the crystallization behavior of the terpolymers was investigated by X‐ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The results show that with increasing CTFE content, the terpolymers contained less of the β phase (it even disappeared), which had an all‐trans chain conformation, and more of the γ phase was found, which became prominent with the trans–trans–trans–gauche conformation. The crystallinity, crystal size, fusion enthalpy, and melting temperatures of the terpolymers decreased with increasing CTFE content. Compared with annealed terpolymers, the terpolymers crystallized from the solution at 35°C included more polar components that contained more trans conformations but had lower crystallinities, melting temperatures, and fusion enthalpies and smaller crystal sizes. These results suggest that crystallization from the solution may be helpful in forming polar crystals, whereas an annealing process at a high temperature is beneficial in perfecting the crystal structure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of monodispersed and lipophilic attapulgite and polystyrene nanorods via surface‐initiated atom transfer radical polymerization
Authors: Zhang Hong , Ye Weichun , Zhou Feng 
Published: July 2011

AbstractA new kind of initiator, 3‐(2‐bromo‐2‐methylacryloxy)propyltriethysiliane (MPTS‐Br), was prepared with a simply hydrobrominated commercial silane coupling agent (3‐methacryloxy‐proplytriethysilane, MPTS). It has been one‐step self‐assemble onto the surface of attapulgite (ATP) nanorods in the dispersion system, and by using this initiator‐modified nanorod (MPTS‐Br‐modified ATP nanoparticles, ATP‐MPTS‐Br) as macroinitiator for atom transfer radical polymerization (ATRP). Structurally well‐defined homopolymer polystyrene (PS) and block polymer poly(styrene‐b‐methyl methacrylate) (PS‐b‐PMMA) chains were then grown from the needle‐shaped nanorods surface to yield monodispersed nanorods composed of ATP core and thick‐coated polymer shell (ATP and PS). The graft polymerization parameters exhibited the characteristics of a controlled/”living” polymerization. The PS‐grafted ATP nanorods could be dispersed well in organic solvent with nanoscale. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The effect of isopropanol addition on enhancement of transdermal controlled release of ibuprofen from ethylene vinyl acetate copolymer membranes
Authors: Emami Shahriar Hojjati , Pirbasti Zahra Hassannejad , Hasani‐Sadrabadi Mohammad Mahdi , Kordestani Soheila S. 
Published: July 2011

AbstractThis work reports the study of the addition of isopropanol on controlled release of ibuprofen from ethylene vinyl acetate (EVAc) copolymer membranes. An EVAc solution in cyclohexane (4% w/v) containing triethyl citrate (7% w/v) as plasticizer was mixed with ibuprofen at three different concentrations of 4, 6, and 8%. Isopropanol was mixed with each of the previous mixtures to form solutions of 1, 3, and 5% isopropanol concentrations. Samples were solvent cast on glass petri‐dishes to form membranes. Home‐made diffusion cells were used for in vitro study. These cells were composed of two compartments, donor (exposed to ambient conditions), and receptor (including buffer solution maintained at 37°C). Each cell was equipped with a sampling port and water in and out system. An ultraviolet spectrometer at 222 nm was used to measure release rates of obtained membranes. The diffusion mechanism for drug release was examined by zero‐order, first‐order, Higuchi and Korsmeyer‐Peppas theories to confirm the obtained membranes follow the matrix‐type system. By increasing the drug concentration from 4 to 8%, drug release (cumulative amount) was improved from 20 (47.5%) to 30 (36%) μg/cm2 after 24 h. Addition of 5% isopropanol to the above samples (4 and 8% loading) further increased drug release to 24 and 43 μg/cm2. Results were in good agreement with the Korsmeyer‐Peppas theory for samples with 4 (% w/w) of ibuprofen. The highest percentage of drug release after 24 h was 59% for the sample with 4% drug loading compared to 50% for the sample with 8% drug loading, both with 5% isopropanol. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Viscoelastic behavior of polymer tape in a wound roll
Authors: Acton Katherine , Weick Brian 
Published: July 2011

AbstractA viscoelastic computational model is developed that uses experimentally determined viscoelastic material properties as input and can be used to predict the behavior of a tape material in a wound roll as stresses relax over time. Experimental creep test results are used to find best‐fit creep‐compliance parameters to describe two high density data storage tape media. The two tapes used in the analysis are a developmental tape with a poly(ethylenenaphthalate) (PEN) substrate and metal particle (MP) front coat similar to linear tape open (LTO4) (referred to in this work as “Tape C”), and LTO3, a commercially available tape with a PEN substrate and MP front coat. Sets of best‐fit creep‐compliance parameters are determined for both tapes. The differences between the predicted behavior using three‐, five‐, and seven‐parameter Kelvin–Voigt models are evaluated, both for a benchmark case and in a viscoelastic wound roll model. The choice of material model is found to significantly influence the predictions of the wound roll model. The differences between different material models for the same material are on the order of the differences found between the two different materials. A material model with a higher number of creep‐compliance parameters, although more computationally expensive, produces better results, particularly over long spans of time. The relative differences between the three‐, five‐, and seven‐parameter models are shown to be qualitatively consistent for several variations in the computational model setup, allowing predictions to be made based on simple benchmarks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Conservation status of the world's hagfish species and the loss of phylogenetic diversity and ecosystem function
Authors: Knapp Landon , Mincarone Michael M. , Harwell Heather , Polidoro Beth , Sanciangco Jonnell , Carpenter Kent 
Published: July 2011

ABSTRACT

Hagfishes represent an ancient and unique evolutionary lineage that plays an important role in the cycling of organic matter and other nutrients to maintain the overall health of the ecosystems they inhabit.
Fisheries worldwide directly profit from the harvesting of hagfishes for leather and food, as well as from the positive habitat effects hagfishes provide for other target species. Overexploitation and destructive fishing practices are major threats to several hagfish species, especially those with restricted or small distributions.
In order to evaluate the effect of these threats on populations, the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria were applied to assess the probability of extinction for all of the world's known hagfish species.
Nine of the 76 hagfish species (12%) were determined to be in threatened categories, indicating an elevated risk of extinction. Particular areas and species of concern include southern Australia where 100% of hagfish species present were determined to be at an elevated risk of extinction and the coast of southern Brazil where up to 50% of hagfish species present are at an elevated risk of extinction. Also of concern, are the species found in the East China Sea, Pacific coast of Japan, and coastal Taiwan where as many as 50% of hagfish species are threatened with extinction.
The loss of hagfish species will have detrimental effects on ecosystems as a whole as well as the fisheries that depend on them, especially in the many areas around the world that have low hagfish species diversity.
Better information, data, regulation and management of hagfish fisheries and other threats to hagfish populations are urgently needed to ensure the survival of these important species.Copyright © 2011 John Wiley & Sons, Ltd.
Demystifying the Millennial student: A reassessment in measures of character and engagement in professional education
Authors: DiLullo Camille , McGee Patricia , Kriebel Richard M. 
Published: July 2011

AbstractThe characteristic profile of Millennial Generation students, driving many educational reforms, can be challenged by research in a number of fields including cognition, learning style, neurology, and psychology. This evidence suggests that the current aggregate view of the Millennial student may be less than accurate. Statistics show that Millennial students are considerably diverse in backgrounds, personalities, and learning styles. Data are presented regarding technological predilection, multitasking, reading, critical thinking, professional behaviors, and learning styles, which indicate that students in the Millennial Generation may not be as homogenous in fundamental learning strategies and attitudes as is regularly proposed. Although their common character traits have implications for instruction, no available evidence demonstrates that these traits impact their fundamental process of learning. Many curricular strategies have been implemented to address alleged changes in the manner by which Millennial students learn. None has clearly shown superior outcomes in academic accomplishments or developing expertise for graduating students and concerns persist related to the successful engagement of Millennial students in the process of learning. Four factors for consideration in general curricular design are proposed to address student engagement and optimal knowledge acquisition for 21st century learners. Anat Sci Educ 4: 214‐226. © 2011 American Association of Anatomists.
Tuning the Excited State of Photoactive Building Blocks for Metal‐Templated Self‐Assembly
Authors: Ahmad Haslina , Meijer Anthony J. H. M. , Thomas Jim A. 
Published: July 2011

AbstractThe reaction of 2,2′:4,4′′:4′,4′′′‐quaterpyridyl (qtpy), with d6 ruthenium(II) (RuII), and rhenium(I) (ReI) metal centers has been investigated. The pendant pyridyl groups on the products have also been methylated to produce a second series of complexes containing coordinated Meqtpy2+. The absorption spectra of the complexes are dominated by intraligand and charge‐transfer bands. The ruthenium(II) complexes display broad unstructured luminescence consistent with emission from a Ru(d)→diimine(π*) manifold in acetonitrile solutions. In aqueous solutions, their emissions are weaker and the lifetimes are shorter. This effect is particularly acute for complexes incorporating coordinated dipyridylpyrazine, dppz, ligands. Although the emission of the ruthenium(II) complexes containing Meqtpy2+ is generally shorter than their qtpy analogs, it is notable that solvent‐dependent effects are much less intense. The rhenium(I) complexes also display broad unstructured luminescence but, compared with the ruthenium(II) systems, they have a relatively short lifetime in acetonitrile. Electrochemical studies reveal that all of the RuII complexes display chemically reversible metal‐based oxidations. ReI complexes only display irreversible metal‐based oxidations. In most cases, the reduction processes were not fully chemically reversible. The electrochemical and optical studies reveal that the nature of the lowest excited state of these complexes—particularly, the systems incorporating dppz—is highly dependent on the nature of the coordinated ligands. Calculations indicate that, although the excited state of most of the complexes is centered on the qtpy or Meqtpy2+ ligands, the excited state of the complexes containing dppz ligands is switched away from the dppz by qtpy methylation. A crystallographic study on one of the dicationic ruthenium(II) structures reveals that it forms an inclusion complex with benzene.
Advanced Regional Biomass Processing Depots: a key to the logistical challenges of the cellulosic biofuel industry
Authors: Eranki Pragnya L. , Bals Bryan D. , Dale Bruce E. 
Published: July 2011

AbstractInterest in commercially viable cellulosic biofuel production has greatly increased due to concerns regarding the sustainability of petroleum fuels. While research into solving the technical issues surrounding cellulosic biofuels is ongoing, much less attention has been paid to solving supply chain challenges such as low bulk density of cellulosic biomass, compositional variability and seasonality of the feedstock, food vs fuel issues, and local environmental concerns. To address these supply chain problems, we explore the concept of Regional Biomass Processing Depots (RBPDs), strategically distributed facilities that procure, pre‐process /pre‐treat and densify biomass into stable intermediate products that are compatible with existing bulk commodity logistical systems. In this perspective, we discuss the fundamental concept of RBPDs, their functionality, advantages, and potential challenges. We then extend the analysis of depots to include enhanced configurations and discuss some technologies that might be deployed in RBPD networks and the valuable coproducts that might be produced via synergies among these technologies. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd
Probiotics function mechanistically as delivery vehicles for neuroactive compounds: Microbial endocrinology in the design and use of probiotics
Authors: Lyte Mark 
Published: July 2011

AbstractI hypothesize here that the ability of probiotics to synthesize neuroactive compounds provides a unifying microbial endocrinology‐based mechanism to explain the hitherto incompletely understood action of commensal microbiota that affect the host's gastrointestinal and psychological health. Once ingested, probiotics enter an interactive environment encompassing microbiological, immunological, and neurophysiological components. By utilizing a trans‐disciplinary framework known as microbial endocrinology, mechanisms that would otherwise not be considered become apparent since any candidate would need to be shared among all three components. The range of neurochemicals produced by probiotics includes neurochemicals for which receptor‐based targets on immune and neuronal elements (intestinal and extra‐intestinal) have been well characterized. Production of neurochemicals by probiotics therefore allows for their consideration as delivery vehicles for neuroactive compounds. This unifying microbial endocrinology‐based hypothesis, which may facilitate the selection and design of probiotics for clinical use, also highlights the largely unrecognized role of neuroscience in understanding how microbes may influence health.Editor's suggested further reading in BioEssays Harvesting the biological potential of the human gut microbiome Abstract